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Under high-temperature conditions, supercritical carbon dioxide (S-CO2) power conversion systems have significant advantages, which show great potential in improving energy utilization efficiency, reducing environmental pollution, and realizing sustainable energy development. S-CO2, as a high-efficiency working fluid, can achieve high efficiency in higher temperature thermodynamic cycles, which helps to reduce fuel consumption and greenhouse gas emissions. Since the S-CO2 power cycle is significant to energy conversion and utilization, many researchers have conducted experimental studies on the convective heat transfer characteristics of S-CO2. However, existing studies mainly focus on low-temperature condition (10-200 ℃), and experimental data under hightemperature condition (200-500 ℃) are scarce. Most of the research conditions on the heat transfer characteristics of S-CO2 have not reached the optimal temperature range of the S-CO2 power conversion system, in order to master the critical data of the relevant design, it is necessary to carry out experimental research on the heat transfer characteristics of S-CO2 under high heat flux conditions, which holds a crucial significance in the development of associated power conversion systems. This paper first introduced the construction process of the S-CO2 forced circulation test bench, and evaluated the uncertainty of the relevant experimental data. The main temperature range of the experiment is 450-800 K, the pressure range is 7.40-10.22 MPa, and the heat flux range is 20-1 000 kW/m2. The heat transfer characteristics of S-CO2 in a vertical tube under high-temperature conditions were studied experimentally, and the effects of thermal acceleration and buoyancy on heat transfer were analyzed. The results show that the heat transfer trend of S-CO2 is similar to that of gaseous CO2 under high-temperature conditions, but the values are quite different, and the influence of thermal acceleration and buoyancy effect on the heat transfer of high-temperature S-CO2 is negligible. Finally, in order to develop a reliable prediction method of S-CO2 convection heat transfer under high-temperature conditions, this paper collected the empirical correlations of S-CO2 heat transfer in vertical heating circular tubes commonly found in the literature, and analyzed them under high heat flux, evaluated and analyzed their experimental prediction high-temperature conditions. It is found that there are some differences with the existing experimental data. Therefore, this paper proposes an empirical correlation suitable for high-temperature S-CO2 heat transfer. The newly proposed heat transfer correlation has the highest calculation accuracy, which calculates 96.65% of experimental data within ±10% error. It can achieve higher accuracy, which meets the actual engineering needs.

Boron neutron capture therapy (BNCT) is an advanced type of radiotherapy at cellular level, and it has attracted great attention as the next-generation cancer therapy and is booming worldwide in recent years. BNCT uses the short-range (4-10 μm) and high linear energy transfer particles produced from the 10B(n,α)7Li thermal neutron capture reaction on 10B to selectively kill tumor cells while suppressing exposure dose to normal tissues. Since the physical property and biological effect of neutron significantly change with neutron energy, the energy spectrum determination of BNCT neutron beam is of vital importance, and it is directly related to the safety and effectiveness of BNCT. In this paper, the multi-foil activation method was used to determine the energy spectrum of BNCT neutron beam. This method has the advantages of insensitive to γ-rays and little disturbance to the measurement field owing to the small size of activation foils. Considering the activation reaction cross section, resonance absorption energy, half-life, irradiation and radioactivity measurement time, disturbance to the measurement field, cost and other factors, seven materials, that is, InAl, AuAl, LaAl, MnNi, CuAl, W and Sc, were selected as the activation foils in this paper. The 640-group activation reaction cross section of each activation foil was prepared. By comparing the ratios of the simulated activation rate per atom, Rorder, to the ideal activation rate per atom, Rideal, for different arrangements of each activation foil, the optimal arrangement of the activation foils was determined, that is, W, InAl, AuAl, LaAl, MnNi, CuAl and Sc along the incident direction of the BNCT neutron beam. Finally, based on the simulation study of the neutron energy spectrum determination with multi-foil activation method, an effective unfolding method was established in this paper. The energy spectra of four BNCT neutron beams based on accelerators and reactors were determined by using the proposed unfolding method. The selected neutron beams of two accelerator-based BNCT (AB-BNCT) facilities are using p-7Li and D-T reactions, respectively, and the selected reactor-based BNCT neutron beams are produced from two still operating reactors, that is, Tsing Hua Open-pool Reactor (THOR) in Taiwan, China and Kyoto University Reactor (KUR) in Japan, which have been used clinically so far. The results show that the unfolded spectra are in good agreement with the initial spectra of the BNCT neutron beams, which causes the average relative deviations are not larger than 7%, and it meets the requirements of practical applications. The proposed neutron energy spectrum determination method is effective, practical and universal, and it provides a feasible method for determining the energy spectrum of BNCT neutron beam.

Metallic magnetic calorimetry holds significant promise in critical defense applications such as nuclear proliferation prevention, radionuclide classification, nuclear safety and anti-terrorism. Metallic magnetic calorimetry realizes energy resolution in the order of a few electron Volts by utilizing the significant contribution of heat capacity of a magnetic origin at milli-Kelvin temperatures in rare-earth doped Au films. For detecting gamma-ray photons with an energy of around 100 keV, the energy resolution is better than 0.1%, 10 times better than the high-purity germanium (HPGe) gamma spectrometer with the highest energy resolution. The metallic magnetic calorimeter can detect other radiation types than gamma rays such as alpha and beta emissions. Metallic magnetic calorimetry can also be used for precise measurement of astrophysical phenomena, cosmic rays and other high-energy physics phenomena. As an critical part of the metallic magnetic calorimeter, the pick-up coil plays a dual role in the sensor unit. It is not only responsible for converting magnetic flux changes into electrical signals, which is subsequently picked up by the SQUID chip, but also responsible for generating persistent excitation magnetic field and magnetizing the rare-earth doped sensor thin-film. The design configuration and electromagnetic parameters of pick-up coil can directly influence the energy resolution of the sensor. In the paper the influences of various parameters (e.g., number of turns of soil, duty ratio) on the electromagnetic characteristics using the finite element method was calculated. The actual pick-up coil size is in the order of micrometers. As direct measurement of such tiny devices is extremely difficult with conventional means and such measurements suffer high errors, in this paper scaled-up samples were measured, and the validity of the simulation model and parameters through comparison with measurement results was verified to provide a reliable foundation for design work of pick-up coils. The calculation results show that the influence of turn number of pick-up meander coil on inductance is more significant than other parameters such as duty ratio and loop pitch. With the increase of the duty ratio, the inductance shows a monotonic decrease trend. When the duty ratio increases from 30% to 70%, the inductance decreases by about 76.4%. On the other hand, with the increase of the turn number, the inductance shows an obvious increasing trend. When the turn number increases from 15 to 75, the inductance increases by about 253%. The simulation result also reveals the magnetic field distribution inside the metal magnetic calorimeter sensor pick-up coil, which provides critical information for the design of the sensor thin film.

In the 250 Wt RTPV (radioisotope thermophoto-voltaic) system, the heat source operates at a temperature above 1 000 ℃, which requires a long term stable thermal insulation devices. In this paper, three types of non-sealed high temperature MLI (multilayer insulator) were prepared by using spike, stainless steel wire mesh and aerogel as separator respectively. Each type was installed and tested in the RTPV prototype separately. The three MLIs are in the same size of 187 mm long, 183 mm wide and 50 mm thick. In MLI with spike separator, 50 metal foil reflectors were pierced several small holes, the spikes from the holes were used as the separator to make the adjacent reflectors in point contact. In MLI with stainless steel wire mesh separator, 50 stainless steel wire meshes were spot weld on each of the metal foil reflectors as the separator to make the adjacent reflectors in line contact. In MLI with aerogel separator, 18 polished metal plates were used as the reflectors, and slender strip aerogels in size of 50 mm×10 mm×2 mm were installed on four corners between adjacent reflectors as the separator. The main configuration of RTPV prototype tested in this paper was as follow. 1) An electric heating source with the size of 99 mm×95 mm×55 mm was used to simulate the radioisotope heat source. The heat source was supported in RTPV center by seven ceramic nails and coated with tungsten alloy radiation emitter. 2) Four optical filters were placed 34 mm away from the heat source and supported by four inner brackets. 3) Photovoltaic cells were installed on the side walls inside the housing with a distance of 14 mm from the optical filter. 4) Two high temperature MLIs were installed on the upper and lower end covers inside the housing. 5) Cold plates were used on the side walls outside the housing. Vacuum thermal performances of RTPV with different MLIs were carried out on a test platform. Based on the test results, some conclusions come out as follows. 1) The aerogel separator has the best performance in controllability of the assembly separating effect, which leads to the best thermal insulation performance consistency between different batches. 2) When the assembly separating effect is well controlled, the high temperature MLI with spike separator has a better insulation performance than stainless steel wire mesh separator. 3) The optical cavity inside the RTPV prototype is consisted of high-temperature MLI and the optical filters. A better closure of the optical cavity significantly contributes to the improvement of the heat utilization, and accesses to a higher heat source temperature. The optical cavity has the best closure performance when using the high temperature MLI with aerogel separator. While the RTPV prototype with aerogel separator input power is 250 Wt, the heat source temperature reaches 1 038 ℃.

[Introduction] As an important thrust of China's "new infrastructure", internet data centers have ushered in opportunities for vigorous development and become new areas of energy use, putting forward higher requirements for the power supply level and capacity of the local distribution network. The innovative application of flexible transmission and distribution technology and key equipment makes the power supply and distribution system more intelligent, more flexible and more reliable, and more able to cope with the challenges brought by the large proportion of DC loads and concentrated high-load energy loads such as Internet data centers, and realize the construction and operation of Internet data centers more low-carbon, more efficient, more reliable and more economical. [Method] Firstly, the basic load requirements of Internet data center were discussed, the overall classification and performance requirements of internet data centers were analyzed. The application of flexible technology in distribution network was studied, with a focus on analyzing and comparing three types of technical routes: "rectification distribution, DC distribution, and AC-DC hybrid power supply and distribution". [Result] The paper provides provides tailored solutions for issues related to system reliability, stability, power quality, power efficiency and acceptance of new energy. [Conclusion] By summarizing the existing research results, flexible transmission and distribution technology is regarded as the core technology of building internet data center. Targeted data center control scheme should be studied from different aspects such as device and algorithms. After summarizing the research results of different aspects, the paper also looks forward to the practice and popularization of head-to-head transmission and distribution technology in internet data center.

Organic wastewater treatment and energy recovery using microbial fuel cell（MFC） are of great significance for pollution reduction and energy saving. The bibliometric analysis of this field from 2008 to 2021 was conducted in this paper. From the two aspects of basic data analysis and hot topic words, this paper discusses the research trends in this field. The results showed that a total of 486 articles were published from 2008 to 2021. China was the country with the highest number of articles published, but had relatively low number of citation per article. According to the evolution of the subject words, the research in this field can be divided into feasibility, performance improvement, and application transformation stages, respectively. The problems to be solved include low power output, high input cost, low system stability and so on at present. Our results may provide a scientific reference for researchers in this field to understand the international progress and breakthrough point of future research, so as to boost the removal efficiency and energy utilization of organic wastewater in future.

With the rapid development of the economy and society and the increasing improvement of people’s living standards, people have gained a scientific understanding of the sub-health state of the body. Many foods with functional claims such as supplementing dietary nutrients, maintaining or improving the body’s health status and reducing the risk of disease have emerged on the market. At the same time, as the country has introduced new policies, laws and regulations such as the “Healthy China 2030” plan to support the development of the health industry, the objective need for food functional claims has become increasingly apparent. But our current laws and regulations do not clearly definite the concept of functional foods and its requirements, so the directions of research, production and sale, market recognition and market regulation of functional foods are unclear. In particular, functional foods cannot be discriminated from health foods, which have a legal definition. In the long term, this will not only fail to promote scientific and technological innovations in ordinary foods, but also hinder the healthy development of the health food industry. In this paper, information concerning the definition and requirements of functional foods is collected and sorted out from government official documents, websites, academic journals, and other authoritative media, and the current focuses of research on functional foods in China and abroad are compared by visual analysis of high-frequency keywords. Moreover, this paper differentiates between the requirements for functional foods and those for health foods, and it suggests that top-level design be made for refined classification of functional foods on the market and puts forward suggestions on how to better connect each category with the current system.

Egg yolk is rich in nutrition and complex in structure. Its major components are egg yolk granules (EYGs) and egg yolk plasma (EYP). The physicochemical properties and microstructures of egg yolk and its components are greatly affected by different treatments during processing, and in turn affect their functional properties. Therefore, this paper reviews the effects of different treatments including salting, alkali treatment, heat treatment and enzymatic treatment on the physicochemical properties (surface hydrophobicity, oil exudation, and protein solubility) and microstructure of egg yolk as well as EYGs and EYP. In addition, this paper discusses the functional changes of egg yolk and its components after different treatments. We expect this review to provide theoretical support for future research on the physicochemical properties and microstructure of egg yolk components and on their effects on the functional properties of egg yolk components.

Temporal domination of sensations (TDS) is a temporal multidimensional dynamic sensory analysis method. This method provides the evaluators with a list of the attributes of products, and the evaluators obtain dynamic multi-attribute sensory evaluation results by selecting the perceptions they think to be dominant at each moment of tasting. In this paper, the concept and process of TDS and its application in food sensory evaluation are reviewed, and future directions in the improvement of TDS are discussed. We anticipate that this paper will provide new ideas for the development of new food products based on an understanding of the dynamic changes of sensory perception during food consumption.

Heat pipe reactor has the advantages of miniaturization, high inherent safety, and simple structure, which has extensive application prospects and research significance in the fields of universe exploration and distributed power generation. A megawatt heat pipe reactor is typically required to arrange thousands of heat pipes in a limited space to export the heat from the core, which increases system complexity and impedes engineering technology realization. To solve this problem, a novel design was proposed in this paper in which the flat heat pipe arrays and plate type fuel elements were tightly fitted to form an integrated core, which has the characteristics of compact structure, small and invariable thermal contact resistance, and stable operation under various operating conditions. Non-uniform heating is common in the actual heat transfer process of the core. The flat heat pipe should be able to achieve stable operation under the non-uniform heating condition to cool the core. Thus relevant research is necessary to clarify the influence of non-uniform heating on the flow and heat transfer characteristics inside the flat heat pipe and verify the feasibility of the flat heat pipe for core cooling. Based on this background, the three-dimensional thermal-flow-solid coupling analysis model of the minimum feature unit of the flat heat pipe array was established using COMSOL multiphysics software, and the research on the thermal-hydraulic and mechanical characteristics of the flat heat pipe under non-uniform heating conditions was conducted in this paper. The reliability of the numerical model was validated by comparing it with the literature. The relative deviation between the numerical simulation result and the experimental reference value is less than 5%. The rationality of a composite wick structure with special type arteries was analyzed using the above numerical models. The results show that the wick structure effectively reduces the flow resistance by changing the liquid return path, making the flat heat pipe work stably. The heat transfer and flow characteristics inside the flat heat pipe under various degrees of heating unevenness were studied, where the symbol Uf was used to define the degree of unevenness in this work. It was found through qualitative research and quantitative analysis that the temperature distribution on the wall surface of the evaporator of the flat heat pipe is affected by the non-uniform heating conditions, and the heat transfer and flow characteristics of the flat heat pipe are not, which suggests that the flat heat pipe could maintain good heat transfer performance and temperature uniformity. The thermal stress distribution of the flat heat pipe under different degrees of heating unevenness was studied furtherly. The results show that non-uniform heating increases the thermal stress of the shell of the flat heat pipe, the peak stress is on the vertex of the front end of the flat heat pipe; this does not cause material failure, and the working stress of the flat heat pipe is within the creep limit of the structural material at high operating temperature. Results of this study show the ability to realize the performance assessment of the flat heat pipe under non-uniform heating conditions, verify that the flat heat pipe designed in this paper could meet the demand of core cooling, and provide a reference method for the performance analysis of related untraditional heat pipes under special conditions.

After neutron irradiation, RAFM steel will produce two types of interstitial dislocation loops (1/2〈111〉 loop and 〈100〉 loop), resulting in radiation hardening and embrittlement after long service. And different types of dislocation loops may lead to different hardening phenomena. However, the formation and transformation processes of different types of dislocation loops are still obscure. Therefore, it is of great significance to clarify the formation and transformation processes of different types of dislocation loops for the evolution of materials’ microstructures and prediction of their properties. In this paper, we presented an improved parallel replica method (PRD), which improved the application of the original PRD method in dislocation loop evolution simulation. Through analyzing the mechanism characteristics of dislocation loop transition and extracting Burgers vector, the improved PRD method accurately identified the state of dislocation loops, and then calculated the simulation of accelerated transition process from 〈100〉 loop to 1/2〈111〉 loop. By combing the dislocation extraction algorithm in OVITO, the synchronous analysis of Burgers vector in the simulation process was realized. During the dislocation loop transforms, its habit plane will change and eventually affect the change of Burgers vector. So Burgers vector was used to redefine the adjudication for transition events in the original PRD method. We adjudicated whether the system undergoes a transition event, based on the existence of 1/2 〈111〉 Burgers vector in the simulated system and whether the proportion of 1/2〈111〉 Burgers vector increases. With such improvements, it would help us avoid lengthy cyclic iterations at some metastable state in our simulation and realize the simulation of accelerated transition phenomenon of 〈100〉 loop to 1/2〈111〉 loop. Finally, numerical experiments were performed to evaluate the effect of our work. The results show that the improved PRD algorithm successfully simulate the changing process of small size 〈100〉 loop to 1/2〈111〉 loop at 1 000 K, and the transition time is faster than the traditional molecular dynamics method. We also observe the coexistence phenomenon of 〈100〉 dislocation segments and 1/2〈111〉 dislocation segments in large size 〈100〉 loop simulation. So far as to the case of 〈100〉 loop with Ni solute elements, it is found that the complete transition to 1/2〈111〉 dislocation loop is happened. In addition, the accuracy of program simulation was verified, and the parallel performance were also analyzed and evaluated in this paper. We achieve about 90% parallel efficiency in the parallel calculating test, which is found much higher than the original PRD method. Moreover, our program has well-fined scalability, so it can be well expanded for the large-scale parallel calculation.

ObjectiveIn order to set or improve the lightning protection measures of ships, it is necessary to evaluate the strike risk of critical equipment and the protection effect of the lightning rod.MethodsIn this paper, a lightning leader fractal model is constructed and applied to a simulation study on the lightning attachment process of a ship. The configuration method of the simulation boundary of the model and the quantitative evaluation method of lightning strike risk are improved, and a quantitative study on the influence of different factors on the lightning strike risk of the ship is performed.ResultsThe simulation results show that the protection probability of the lightning rod in the middle of the ship is more than 75% under the basic configuration. The bow, stern and antenna far away from the lightning rod have a relatively large risk of circling strike. The lightning strike probability of the shipboard antenna is lower if the lightning initiation position is closer to the lightning rod, the lightning current is greater or the lightning rod is higher.Conclusions The lightning leader fractal model constructed in this paper can be used to investigate the weak links of direct lightning protection on the surface of ships, which can provide useful references for the direct lightning protection design of ships.

ObjectivesIn order to improve ship propulsion performance and efficiency, and overcome such obstacles as numerous propeller parameters, complicated modeling, slow convergence of hydrodynamic numerical calculations and turbulent wake field effects, this paper proposes an efficient propeller optimization method.MethodsA parameterized propeller constructed with non-uniform rational B-spline based free form deformation (NFFD) technology is used as the output. The CFD numerical simulation is applied to predict its performance characteristics and the Gaussian approximate prediction model of the propeller performance is established based on the simulation data. The optimization model aims to improve efficiency and reduce the torque coefficient by using the second-generation non-dominated sorting genetic algorithm (NSGA-II) method to obtain the optimal solution.ResultsThe results show that under the uniform flow field and wake field behind the ship, the optimization results of the propeller have similar laws; that is, the blade width and thickness of the propeller show a decreasing trend, while the inclination angle shows an increasing trend. The flow velocity decreases in the wake field behind the ship, so the reduction in width and thickness and increase in inclination angle of the propeller blade are smaller than those in the uniform flow field. ConclusionThe method proposed in this paper can be used to achieve the more efficient optimization design of propellers under uniform flow fields and wake fields behind ships.

ObjectiveThis paper analyses the fatigue life of weld cracks in a large opening coaming with a conical shell under uniform pressure load. MethodsFirst, a finite element model of an underwater pressure-hull structure is built. Next, the peril point and its fatigue life are calculated using the structural strain method. Finally, the accuracy of the structural strain method used in the fatigue life evaluation of the underwater pressure-hull structure is verified through a comparison with the calculated results of the experimental data model.ResultsThe results show that the maximum structural stress is located at the weld of the coaming near the large end, which is the same as the appearance location of fatigue cracks in the experiment. The fatigue life calculated using the structural strain method shows good agreement with the experimental results, and the data of the model fatigue experiment is located in a narrow band of the master e-N curve. The normal structural stress is far greater than the shear structural stress at the peril point of the coaming weld. ConclusionsThe structural strain method can effectively solve problems with the fatigue life of weld cracks in a large opening coaming with a conical shell. Under the load conditions of this paper, the initial crack at the peril point should be type one.

Ozone has become one of the major global environmental pollutants, and has attracted more and more attention in the field of air quality and public health. Ground-level ozone concentrations have been increasing in recent years, causing serious burden to the human respiratory system and social economy. Asthma and chronic obstructive pulmonary disease (COPD) are two common airway diseases. Ozone exposure can induce the occurrence, development and exacerbation of chronic airway diseases, short-term ozone exposure can induce non eosinophilic asthma, long-term ozone exposure can induce COPD, and ozone exposure can also induce acute attack of asthma and acute exacerbation of COPD. The effects are mainly that ozone exposure can mediate inflammatory response, oxidative stress, airway hyperresponsiveness, and DNA damage, and lead to decreased lung function, changes in microbial communities, and disruption of the air-blood barrier. This paper reviewed a series of epidemiological studies and animal experiments on asthma and COPD related to ozone exposure in recent years, and mainly generalized the effects of ozone exposure on airway diseases. Finally, this paper summarized the shortcomings of existing studies, providing a beneficial direction and ideas for further research on the hazards of ozone exposure on asthma and COPD and for exploring new intervention targets.

As a biometric technology, gait recognition is usually considered a retrieval task in real life. However, because of the small scale of the existing radar gait recognition dataset, the current studies mainly focus on classification tasks and only consider the situation of a single walking view and the same wearing condition, limiting the practical application of radar-based gait recognition. This paper provides a radar gait recognition dataset under multi-view and multi-wearing conditions; the dataset uses millimeter-wave radar as a sensor to collect the time-frequency spectrogram data of 121 subjects walking along views under multiple wearing conditions. Eight views were collected for each subject, and ten sets were collected for each view. Six of the ten sets are dressed normally, two are dressed in coats, and the last two are carrying bags. Meanwhile, this paper proposes a method for radar gait recognition based on retrieval tasks. Experiments are conducted on this dataset, and the experimental results can be used as a benchmark to facilitate further research by related scholars on this dataset.

The performance of machine learning-based radar target recognition models is determined by the respective model and data to be analyzed. Currently, radar target recognition performance evaluation is based on accuracy metrics, but this method does not include the evaluation metrics regarding the impact of data quality on recognition performance. Data separability describes the degree of mixture of samples from different categories. Furthermore, the data separability metric is independent of the model recognition process. By incorporating it into the recognition evaluation process, recognition difficulty can be quantified, and a benchmark for recognition results can be provided in advance. Therefore, in this paper, we propose a data separability metric based on the rate-distortion theory. Extensive experiments on multiple simulated datasets demonstrated that the proposed metric can compare the separability of multivariate Gaussian datasets. Furthermore, by combining it with the Gaussian mixture model, the designed metric method could overcome the limitation of the rate-distortion function, capture the data’s local separable characteristics, and improve the evaluation accuracy of the overall data separability. Subsequently, we applied the proposed metric to evaluate the recognition difficulty in real datasets, the results of which validated its strong correlation with average recognition accuracy. In the experiments on evaluating the effectiveness of convolutional neural network modules, we first quantified and analyzed the separability trend of the feature extracted by each module during the testing phase. Further, we incorporated the proposed metric as a feature separability loss during the training phase to participate in the network optimization process, guiding the network to extract a more separable feature. This paper provides a new perspective for evaluating and improving the neural network recognition performance in terms of feature separability.

Purposes Coal mine underground terrain is complex and changeable and the air contains a variety of inflammable and explosive gases, which has high risk. In order to reduce the risk and improve the efficiency of inspection, a separable wheelleg quadruped robot with multiple motion modes is proposed in this paper. Methods Five main motion modes of the robot, including leg mode, wheel mode, wheel leg mixed mode, body separation combined mode, and arms clamping mode were analyzed. The single leg structure parameters were described and the leg working space of the robot was drawn on the basis of Monte Carlo method. The acceleration reversal method was used to eliminate the abrupt change of foot longitudinal acceleration, and the foot trajectory under the leg mode was optimized. According to the trajectory characteristics of quintic polynomial, the wheel leg switching trajectory of multiple motion modes was planned. On the basis of the joint simulation environment of Webots and MATLAB, the stability of Trot gait and the flexibility of wheel-leg mode switching track under the robot leg mode were verified. Conclusion The research content of this paper provides a theoretical basis for the separable wheelleg quadruped robot that can carry out inspection in mine environment.

Purposes PID controllers are widely used in the control of integral systems. In the practical application of the integral system, the control effect is usually affected by the delay time. At the same time, the controller will be affected when the controlled integral parameter changes greatly. Methods In this context, an adaptive dynamic PID controller parameter tuning method suitable for time delay integral systems is proposed in this paper, considering the influence of parameters such as the voltage of the integral system, the variation range of the controlled object, and delay time. The relationship between the PID controller parameters and the integral system control object is clarified. At the same time, the tuning of the differential filter parameters in practical applications is considered. Conclusion In Simulink, a non-linear system with a 10-fold change of the controlled integral parameter is simulated, and the dynamic control of the non-linear system is achieved with the method proposed in this paper, which shows good control results. Besides, the application feasibility of the method is verified in a practical PWM control system.

The LBE-cooled reactor is one of the important choices for sustainable and safe development of nuclear energy systems in the future. The safety issues involved with the steam generator tube rupture (SGTR) accident must be considered in the design and operation of such reactors. The essence of the evolutions during this SGTR accident for LBE-cooled reactors is focused on the interaction behaviors between high temperature liquid metal LBE and pressurized water. For such considerations, relevant researches on the mechanistic experiments and numerical simulations have been carried out at home and abroad. However, with respect to the numerical simulations of SGTR accident in LBE-cooled reactor, the traditional system analysis codes based on the typical two-fluid six-equations model, such as RELAP5, ATHLET, etc., are not appropriate here. And the targeted simulation codes used for SGTR in LBE-cooled reactors are still rare, researches in foreign countries are focused on the multi-phase, multi-components, multi-velocities based computational fluid dynamics (CFD) and neutronics coupled code SIMMER-Ⅲ which is developed to analyze the serious accidents of liquid metal cooled fast reactors, such as LBE-cooled reactors or sodium cooled reactors. While domestically, researches are focused on the multi-phase flow codes including NTC-2D and MC3D. It is absolutely of great significance to conduct further and in-depth studies on the fundamental models and numerical algorithms for thus SGTR accident. So, aiming at the interaction behaviors between LBE and water, which is one of the significant scientific issues involved with the accident evolution characteristics and behaviors of SGTR in LBE-cooled reactors, investigations on the basic theories, constitutive models and numerical algorithm were performed in this paper. A new three-fluid code including LBE, liquid water and vapor mixtures was developed, and its verification work was performed by using the published experimental data abroad including the water injecting into LBE liquid metal pool experiment in a small experimental apparatus by Japan JAEA and water injecting into LBE pool experiment in large experimental LIFUS5 series facilities by Italy ENEA. The results show that the new code developed in this paper agrees reasonably on the whole with the experimental results, but certain deviations still exist at some local details compared with the experimental results. On the whole, the relevant research achievements, including the critical related models, algorithms and code modules are able to simulate the interaction behaviors between LBE and water reasonably. The code developed in this paper is expected to provide certain theoretical and technical support for the accident analyses and safety evaluations of SGTR accident in LBE-cooled reactors. Meanwhile, more in-depth researches on the optimizations of the critical models and algorithms should be carried out in the future work.

Monte Carlo simulation has become an effective method for solving different physical problems, which is especially advantageous in the particle transport problems with complex geometric models. Charged particle transport simulation programs based on Monte Carlo method are widely used in medical therapy, radiation protection, accelerator design and other fields. Although the domestic neutron and photon transport simulation programs are well developed, there are few programs being able to do charged particle transport simulation. In addition, the energy range for programs based on the intranuclear cascade model and evaporative fission model is usually high, above several tens of MeV. For medium and low energy proton transport, the accuracy of nuclear reaction simulations based on nuclear databases is better than that of models. The biggest problem with Monte Carlo methods for simulating charged particle transport calculations is that the number of collisions of charged particles is too frequent. Therefore, this paper was based on the condensed history method to simulate the proton transport. In this study, with the application of key physical model of charged particle transport, such as the continuous slowing down approximation theory, multiple scattering theory and energy straggling model, a framework of heavy charged particles transport simulation program was established. Based on nuclear database of ENDF/B-Ⅶ.0 proton-nucleus interactions, the proton transport simulation function was implemented on the NPTS (neutron-photon transport simulation program). The extended NPTS program supported the simulation of proton transport problems in the energy range from 1 keV to 150 MeV and multi-coupling transport calculations of protons, neutrons, photons and electrons. A comparison of the stopping power of protons, deuterons and alpha particles in common materials with SRIM was carried out by the NPTS program, which proved the correctness of NPTS in calculating the stopping power of charged particles. The numerical results of neutron yield, average energy and angle for the thick target model agree well with GEANT4, MCNP6 and experimental results. In order to fully verify the program, a proton treatment chamber model with larger spatial dimensions and more complex geometry was used for the study. The neutron flux distribution inside the treatment chamber obtained by NPTS was basically consistent with GEANT4. The accuracy of the NPTS simulations of proton transport and multiparticle coupled transport was verified by several test models. Moreover, the proton energy and continuous slowing down approximation range curves obtained from the NPTS calculations can be used to quickly estimate the target thickness at maximum neutron yield, providing a favourable reference for BNCT (boron neutron capture therapy) target design. This paper effectively extends the application of the NPTS program in accelerator target design, shielding analysis, and radiation protection. The research effectively improves the application value of NPTS program, as well as enriching the research method of medium and low energy proton transport programs in domestic.

Recently, cement matrixes become a mainstream solution to address the stabilization of radioactive spent resins. Generally, the cumulative dose of spent resin cemented waste form will reach approximately 106 Gy over a disposal lifetime of 300 years. Due to the organic properties of spent resin, namely producing gas if being irradiated, it inevitably affects the mineral phase of cement waste forms. Therefore, the content and composition of the mineral phase could be key factors determining the performance of cement waste forms. With that in mind, in this paper, the influence of the above factors on ordinary Portland cement (OPC) was explored especially. Specifically, based on the Gibbs free energy minimization principle, the influence of three gases generated by irradiation of waste resin, namely H2, CH4 and CO2, on the mineral phase composition and total volume of ordinary Portland cement was discussed. Thereafter, the evolution of the mineral phase composition of ordinary Portland cement over time was investigated based on the rate of irradiated gas production. In this work, all the experiments were produced by GEMS software based on the thermodynamic Gibbs free energy minimization method. Meanwhile, the formulation for cement solidification of spent resin meets the standard of GB 14569.1-2011. From the experimental results, several important findings were obtained. Firstly, only a small amount of H2 and CH4 reacts with the cement hydration products, which causes the dissolution of the mineral phase with high Ca/Si, while the total volume of the mineral phase is almost invariant. Secondly, in the prior phase, CO2 first reacts with the portlandite in the cement hydration products. After the portlandite dissolute completely, the silicate minerals start to dissolve, forming a system composed of abundant carbonate and a few clay minerals, which decreases the total volume of the mineral phase. Thirdly, during the predicted 160 years, the effects of spent resin irradiation gases on the cemented waste form are consistently dominated by CH4 and H2, while the performance of the cemented waste form is stable. However, the risk of rupture and explosion caused by the accumulation of H2 and CH4 in the waste packaging containers and the risk of radioactive release due to carbonation of the cemented waste form by CO2 should not be overlooked. In summary, the above results reveal the evolution law of degradation of cement solidified body caused by waste resin irradiation gas. The results of this paper provide effective data support for the safety evaluation of waste resin treatment by cement solidified form.

Acetic acid is the major volatile acid in fruit wine and an excessive content of acetic acid will seriously affect the sensory quality of fruit wine. During alcoholic fermentation, acetic acid is mainly formed by the metabolism of Saccharomyces cerevisiae. Therefore, fully understanding the regulation mechanism of acetic acid metabolism by S. cerevisiae, and breeding low acetic acid-producing strains are of great significance to solve the problem of excessive acetic acid in fruit wine. In this paper, recent progress in research on the metabolic pathways and key regulatory genes of acetic acid in S. cerevisiae is reviewed. Furthermore, this paper proposes the idea that omics technologies and quantitative trait locus mapping could be applied to explore the molecular mechanism of the regulation of acetic acid production by S. cerevisiae. Finally, the application of three functional strain-breeding methods in the breeding of low acetic acid-producing strains is summarized. This review is expected to provide a reference for obtaining excellent strains with low yield of acetic acid for precise regulation of acetic acid in fruit wine.

[Introduction] With the increasing demand for clean energy, the offshore wind power sector has seen a spurt of progress in recent years, and the bucket foundation has become the preferred choice for offshore wind turbines considering its good economy, convenient construction, and recyclability. Due to the widespread distribution of seismic zones in China, the seismic performance of bucket foundation is a crucial consideration for structural design. The bucket foundation is featured by high structure stiffness, so that the probability of structure damage caused by earthquake is low, and the failure under earthquake is mainly caused by the liquefaction of the foundation soil. For this purpose, the paper focuses on the seismic performance of bucket foundation in sandy soil. [Method] The liquefaction resistance of sandy soil for bucket foundation was analyzed by shaking table tests in this paper. The study objects included four types of bucket foundation in sandy soil, namely mono-bucket foundation (MBF), composite bucket foundation (CBF), three-bucket jacket foundation (TBJF) and four-bucket jacket foundation (FBJF). [Result] By carrying out shaking table tests, the excess pore pressure ratios of sandy soil for different types of bucket foundation under earthquake are obtained, and the impact mechanism of bucket foundation on the anti-liquefaction performance of sand soil is clarified. [Conclusion] The bucket foundation can improve the liquefaction resistance of sand, since the additional load effect of the superstructure and the hoop effect of bucket skirt weakens its shear shrinkage. The test results of MBF are compared with those of CBF, and the test results of TBJF are compared with those of FBJF. It is found that the seismic performance of CBF and FBJF is respectively superior to that of MBF and TBJF.

[Introduction] In the context of the new power system, low-carbon maintenance of wind turbines and coordinated maintenance with conventional wind turbine generator systems (WTGS) need to be solved urgently. In this paper, taking into account the impact of multi-attribute meteorological factors and low carbon and economic needs, an optimization model for wind power, hydropower and thermal power combined low-carbon maintenance based on continuous hidden Markov model is established. [Method] Firstly, dynamic tracking of wind farm maintenance capacity was realized by taking rainfall, wind speed and lightning hazard degree as the observation sequence, taking maintenance capacity as hidden state sequence, and using continuous hidden Markov model (CHMM) process. Then, an optimization model for wind power, hydropower and thermal power combined low-carbon maintenance was constructed by taking the optimal maintenance capacity as the decision-making basis, taking the minimum total cost as the optimization objective, and taking the maintenance constraints and system control constraints into consideration. Finally, took the IEEE30-node system as an example. [Result] The results show that the proposed model has more significant economic benefits and low carbon characteristics. [Conclusion] The research in this paper has high theoretical value for the operation and maintenance of WTGS, and has strong engineering applicability.

[Introduction] With the development of wind power generation technology, the unit capacity of permanent magnet wind generator is increasing, and the heating power is also increasing. The heat dissipation of generator is facing unprecedented challenges. How to effectively solve the problem of generator temperature rise and heat dissipation difficulty has been the focus of our study. [Method] Based on the STAR-CCM+ software platform, an integrated numerical simulation method for generator heat dissipation and cooling was proposed in this paper. The reliability of the numerical calculation method was verified by comparing the calculated values with the experimental values. On this basis, a study was conducted on the internal temperature distribution law and the factors influencing the cooling system heat dissipation performance of the high power permanent magnet wind generator. [Result] Under the rated power, the highest temperature of the winding and stator core appear in the middle area. If the process conditions allow, the cooling water pipe should be as close to the winding as possible to take away more heat. The stator core temperature and winding temperature can be reduced significantly by increasing the total intake air volume of the generator. The intake air temperature has a linear relationship with the maximum temperature of the winding and stator core. For every 5℃ decrease in the intake air temperature, the maximum temperature will be reduced by about 1.4℃. Reducing the intake air temperature can improve the heat dissipation performance of the generator to a certain extent. The intake water temperature has a linear relationship with the maximum temperature of the winding and stator core. For every 5℃ decrease in the intake water temperature, the maximum temperature will be reduced by about 3.3℃. Reducing the intake water temperature can greatly improve the heat dissipation performance of the generator. In addition, the gap between the cooling water pipe and the stator core greatly hinders the heat transfer of the cooling water pipe. Filling the gap with materials with good thermal conductivity can effectively improve the heat dissipation performance of the generator. [Conclusion] The conclusions drawn in this paper can effectively guide the heat dissipation design of permanent magnet wind generator and ensure the safe operation of wind turbines in normal work.

[Introduction] With the steady progress of the carbon peaking and carbon neutrality goals, more and more distributed renewable energy is connected to the power grid. Among them, in economically developed coastal areas with heavy power load, vigorously developing offshore wind power has become a hot point of wide concern for scholars at home and abroad. However, the inherent intermittency of wind power generation, especially when the offshore wind farm is actively disconnected from the main grid during typhoons, can adversely affect the receiving-end grid. [Method] In order to realize the friendly access of offshore wind power during typhoon, considering the advantages of hydrogen energy storage such as high storage efficiency, low emission and wide application, this paper proposed a collaborative control method between offshore wind farm and hydrogen management system (HMS). On the one hand, during the period of typhoon approaching, this method could maximize the use of wind energy for power generation under normal operation. On the other hand, when the typhoon passed through and the offshore wind farm was gradually disconnected from the grid, the hydrogen energy system released electric energy to alleviate the active power drop of the wind farm and solve the problems such as the ramp rate in the operation of the traditional wind turbine generator systems, so as to reduce its adverse impact on the receiving-end grid and effectively smooth the volatility of the offshore wind power output. This paper firstly introduced the physical modeling method and control model of offshore wind farm and hydrogen energy system in detail, and explained the collaborative control strategy between them according to the typhoon period. [Result] Finally, simulation results show that the proposed method enables the offshore wind farms to be more flexible and friendly to meet the grid-connected operation during typhoons. In addition, the hydrogen energy storage system can maximize the use of wind energy for power generation under normal operation. [Conclusion] Control the hydrogen energy system to release electric energy during typhoons can solve the problems such as the ramp rate of the traditional wind turbine generator systems, so as to reduce its adverse impact on the receiving-end grid.

[Introduction] The growth of wind power industry is accelerating faster than ever worldwide, at the same time, the waste generation from end-of-life wind turbine blades is expected to peak in recent years. Efficient recycling of end-of-life wind turbine blades has become a key issue affecting the sustainable development of the wind power industry and its low-carbon-footprint target. [Method] Traditionally, majority of the end-of-life blades were either buried or incinerated after being dismantled, causing resources wasting and severe environmental problems. In this context, this paper reviewed the mainstream domestic and international recycling processes of end-of-life wind turbine blades such as mechanical recycling, pyrolysis, chemical recycling and comprehensive recycling, and analyzed their corresponding advantages and disadvantages. [Result] By summarizing the industrial recycling application scenarios, this paper provides suggestions and prospects for the prospective recycling market of the end-of-life wind turbine blades. [Conclusion] Wind power industry plays an important role in realizing the "carbon-peaking and carbon-neutrality" goals through assisting in implementation of the energy-conservation and emission-reduction strategy. However, the wind turbine blade recycling market is currently in the exploratory stage with medium and small-size, there is an urgent need for policies, standards and technology development to help with its large scale industrialization. This paper illustrates current status and development trend of domestic and international recycling technology and application scenarios of end-of-life wind turbine blades, and aims to provide the scientific references for the sustainable and low-carbon development of the wind power industry.

[Introduction] In order to guarantee urban power supply and offshore wind power utilization without building new power lines, the paper aims to establish a electricity transmission strategy based on wind-coal-battery- hydrogen -CCUS multi energy coupling and bundling system, which is analyzed theoretically and verified by simulation.[Method] To verify the effectiveness of the strategy, four experimental schemes (separate transmission of wind and coal power, bundled transmission of wind and coal power without operation coupling, bundled transmission of wind and coal power with operation coupling, and wind-coal-battery-hydrogen-CCUS coupled transmission) were set up, and based on the HOMER software environment and particle swarm optimization algorithm, the system operation simulation and index calculation of the test scheme are carried out.[Result] According to the simulation results, compared with normal separate transmission strategy, power transmission line capacity of system applying wind-coal bundled transmission strategy can be decreased by 2.2 GW, with an average utilization rate of 59%, i.e. 21%~23% higher. In the case that the wind power and coal power share the same transmission line without coordinated operation, the wind power curtailment is 164 GWh in total. System applying wind-coal-battery–hydrogen-CCUS bundled transmission strategy could avoid wind power curtailment and reduce carbon emission from unit power supply by about 30~33g/MWh. [Conclusion] In conclusion, the electricity transmission strategy established by this paper is supposed to be feasible and effective and contributing to planning and construction of offshore wind power project.

SignificanceAgricultural machinery serves as the fundamental support for implementing advanced agricultural production concepts. The key challenge for the future development of smart agriculture lies in how to enhance the design, manufacturing, operation, and maintenance of these machines to fully leverage their capabilities. To address this, the concept of the digital twin has emerged as an innovative approach that integrates various information technologies and facilitates the integration of virtual and real-world interactions. By providing a deeper understanding of agricultural machinery and its operational processes, the digital twin offers solutions to the complexity encountered throughout the entire lifecycle, from design to recycling. Consequently, it contributes to an all-encompassing enhancement of the quality of agricultural machinery operations, enabling them to better meet the demands of agricultural production. Nevertheless, despite its significant potential, the adoption of the digital twin for agricultural machinery is still at an early stage, lacking the necessary theoretical guidance and methodological frameworks to inform its practical implementation.ProgressDrawing upon the successful experiences of the author's team in the digital twin for agricultural machinery, this paper presents an overview of the research progress made in digital twin. It covers three main areas: The digital twin in a general sense, the digital twin in agriculture, and the digital twin for agricultural machinery. The digital twin is conceptualized as an abstract notion that combines model-based system engineering and cyber-physical systems, facilitating the integration of virtual and real-world environments. This paper elucidates the relevant concepts and implications of digital twin in the context of agricultural machinery. It points out that the digital twin for agricultural machinery aims to leverage advanced information technology to create virtual models that accurately describe agricultural machinery and its operational processes. These virtual models act as a carrier, driven by data, to facilitate interaction and integration between physical agricultural machinery and their digital counterparts, consequently yielding enhanced value. Additionally, it proposes a comprehensive framework comprising five key components: Physical entities, virtual models, data and connectivity, system services, and business applications. Each component's functions operational mechanism, and organizational structure are elucidated. The development of the digital twin for agricultural machinery is still in its conceptual phase, and it will require substantial time and effort to gradually enhance its capabilities. In order to advance further research and application of the digital twin in this domain, this paper integrates relevant theories and practical experiences to propose an implementation plan for the digital twin for agricultural machinery. The macroscopic development process encompasses three stages: Theoretical exploration, practical application, and summarization. The specific implementation process entails four key steps: Intelligent upgrading of agricultural machinery, establishment of information exchange channels, construction of virtual models, and development of digital twin business applications. The implementation of digital twin for agricultural machinery comprises four stages: Pre-research, planning, implementation, and evaluation. The digital twin serves as a crucial link and bridge between agricultural machinery and the smart agriculture. It not only facilitates the design and manufacturing of agricultural machinery, aligning them with the realities of agricultural production and supporting the advancement of advanced manufacturing capabilities, but also enhances the operation, maintenance, and management of agricultural production to better meet practical requirements. This, in turn, expedites the practical implementation of smart agriculture. To fully showcase the value of the digital twin for agricultural machinery, this paper addresses the existing challenges in the design, manufacturing, operation, and management of agricultural machinery. It expounds the methods by which the digital twin can address these challenges and provides a technical roadmap for empowering the design, manufacturing, operation, and management of agricultural machinery through the use of the digital twin. In tackling the critical issue of leveraging the digital twin to enhance the operational quality of agricultural machinery, this paper presents two research cases focusing on high-powered tractors and large combine harvesters. These cases validate the feasibility of the digital twin in improving the quality of plowing operations for high-powered tractors and the quality of grain harvesting for large combine harvesters.Conclusions and ProspectsThis paper serves as a reference for the development of research on digital twin for agricultural machinery, laying a theoretical foundation for empowering smart agriculture and intelligent equipment with the digital twin. The digital twin provides a new approach for the transformation and upgrade of agricultural machinery, offering a new path for enhancing the level of agricultural mechanization and presenting new ideas for realizing smart agriculture. However, existing digital twin for agricultural machinery is still in its early stages, and there are a series of issues that need to be explored. It is necessary to involve more professionals from relevant fields to advance the research in this area.

Deep-frying is a traditional cooking method in China, endowing the product with unique crispy characteristic but also greasiness. High-calorie fried foods can create health risks. Many attempts have been made by researchers to reduce the absorption of oil during the frying process while ensuring the good quality of deep-fried products. This paper reviews the oil-absorbing behavior of deep-fried starch-based products during the frying process and describes several methods to regulate the oil content of deep-fried products. Adding functional ingredients (proteins or starches and a combination of hydrocolloids with the main ingredients of the product) is in line with the current trend of nutritious and low-fat foods. Coating technology, which utilizes natural macromolecules as an oil barrier, has promising applications in the production of low-fat fried foods. In addition, new frying technologies such as vacuum frying, air frying and spray frying are becoming increasingly mature, and can gradually replace traditional frying for the production of low-fat fried products according to the needs of industrial production. All regulatory measures described in this paper can reducing the oil content of different fried products to different degrees, which will provide a scientific and theoretical basis for selecting a suitable measure for oil reduction in different fried starch-based products based on their oil absorption mechanisms, and provide a theoretical reference for the development of low-fat fried products.

In recent years, the number of patients with diabetes or obesity has increased rapidly, and the glycemic index (GI) of grains has attracted attention. Using GI value to guide the choice of grains is of great significance to the prevention and control of chronic diseases such as diabetes. However, the GI value of grains is influenced significantly by processing methods and is often directly related to measurement methods. Therefore, this paper summarizes the current methods used to determine the GI value of foods as well as their advantages and disadvantages. Thereafter, this review also analyzes the effects of different processing methods on the GI values of grains and their products, and explains the possible mechanism for changes in the GI value of grains from the perspective of the interaction between various components in grains caused by processing methods. This paper is expected to provide an effective basis for the prediction of changes in the GI value of grains and the selection of processing methods, and also provide a reference for the research and development of grain products with low GI value.

The purpose of this paper is to investigate a class of variational inclusions with ϕ accretive type mappings in the Banach space X. We prove the existence and uniqueness of solutions to the variational inclusions and the convergence of the three-step iterations with errors. The results in this paper improve and extend the earlier results obtained by professor ZENG and et al..

ObjectiveThis paper aims to analyze the explosion loading characteristics in a confined ship cabin with a pressure relief hole, and the impact of the pressure relief hole in propagating shock loads from the explosion affected cabin to the adjacent cabin.MethodFirst, a numerical simulation of the explosion venting effect on a double cabin is conducted, and the pressure drop of the explosion affected cabin is analyzed with the Baker empirical formula. On the basis of the pressure distribution characteristics in the adjacent cabin, the empirical formula for the initial peak pressure in the adjacent cabin is deduced using the least squares principle.ResultsThe results indicate that the increase in the size of the pressure relief hole will change the initial state of the pressure field in the explosion affected cabin and adjacent cabin during the explosion venting process, weakening the pressure convergence and superposition in the explosion affected cabin, and strengthening the pressure propagation in the adjacent cabins. Without considering the influence of structural deformation, the shock wave presents a peach-shaped and jellyfish-shaped pressure distribution after passing through the pressure relief hole, and the phenomenon of pressure stratification and attenuation with angle occurs.ConclusionThe results of this paper can provide references for the study of explosion load characteristics in cabins.

This paper starts with the importance and basic physical phenomena of underwater explosion, explaining the background and significance of ship damage and protection research under underwater explosion loads, research progress and status, as well as key challenges. To address these challenges, the paper elaborates on popular underwater explosion theories, models and methods. In terms of theoretical and computational research, a unified theory of bubble dynamics is presented, as well as a transient strong non-linear gas-liquid-solid fully coupled model and numerical method for underwater explosion, which have been used to develop a fundamental industrial software FSLAB capable of solving practical problems in fluid-structure interaction. In terms of experimental research, underwater explosion surrogate experimental methods and model testing methods are elaborated. Based on this, theoretical analysis, computational and experimental results in the field of ship damage and protection under underwater explosion loads are presented and discussed, aiming to provide references for underwater explosion-related research.

The yields of 85Krm, 87Kr and 88Kr of neutron-induced fission of 239Pu are important nuclear parameters. They have a moderate half-life, are β- decay and emission γ-rays with a certain probability, so it is appropriate to use γ-ray spectrum method to determine their yield. At present, there are few experimental data with large deviation abroad and no experimental results have been reported in China. The yield measurements of 85Krm, 87Kr and 88Kr of thermal-neutron-induced fission of 239Pu were carried out based on the irradiation of plutonium target by Xi’an Pulsed Reactor rabbit system. The purified plutonium solution was then titrated and dried to prepare the silica-encapsulated plutonium target. Three kinds of measurement experiments were designed: γ-ray nondestructive method for the relative yield of 88Kr and 99Mo, gas-solid separation method for 85Krm, 87Kr and 88Kr and γ-ray nondestructive method for the relative yield of 85Krm, 87Kr and 88Kr. After the target irradiation and cooling, the fission products were measured by the above-mentioned methods. The efficiency of the three kinds of experimental samples was calibrated by the equivalent efficiency curve method. The plan source of organic glass package was used to equate the efficiency calibration of quartz tube source, and the plan source of stainless steel package with the same thickness and material as the measuring source was used to equate the efficiency calibration of 50 mL gas source. By Monte Carlo simulation, the suitable equivalent position was selected, and the efficiency value was fine corrected (less than 0.8%). The uranium target was prepared in the same way of plutonium target. The relative yields of 85Krm, 87Kr and 88Kr of 235U fission induced by thermal neutron measured by gas-solid separation after irradiation are consistent with the recommended values of the evaluation database, which indicates that the release rates of 85Krm, 87Kr and 88Kr in the plutonium target are the same. After modified by the influence of non-primary neutron field and non-primary isotope, the fission yields of 85Krm, 87Kr and 88Kr were obtained based on the measured relative yield with reference product 99Mo and the yield of 99Mo given by ENDF/BⅧ.0 evaluation database. The measured yields are (0.559±0.020)%, (0.992±0.034)% and (1.264±0.037)%, respectively, which are consistent with the evaluation value of the database and the uncertainty is significantly reduced compared with other literature value. In this paper, the retrieval and deduction methods of γ-ray energy peak interference ratio in measurement are universal, but the uncertainty of theoretical yield may be added. The experimental method in this paper can also provide reference for the measurement of fission product yield at different neutron energy points.

To meet the requirements of mitigating the climate change, a large scale deployment of nuclear energy is expected, which impulses higher efficiency in the utilization of uranium resources. As one of the promising solutions, the integral fast reactor featuring in a high internal breeding can reach a high burn-up, low reprocessing mass, and a long refueling period. In this paper, the relationship between the breeding characteristics and two main design parameters of the core, the rod diameter and the pitch-to-diameter ratio (P/D), was studied. The negative impact on internal breeding caused by the measures for reduction of sodium void reactivity was also analyzed. All calculations were carried out with the Monte Carlo code RMC and ENDF/B-Ⅶ.1 continous-energy ACE data libraries. In each case the breeding characteristics were shown by both breeding ratio of the fissile nuclides and the regeneration ratio of the TRU nuclides. The variation of keff, fissile nuclides, TRU nuclides along with burnup were also illustrated. The calculation results indicate that the internal breeding can be significantly enhanced by increasing the rod diameter and by decreasing the P/D. With the current U-Pu-10Zr fuel parameters, a satisfactory burnup reactivity curve can be realized with the rod diameter at 7.0 mm and the P/D at 1.14, taking into account a balance between neutronics and thermal-hydraulics. The positive sodium void reactivity effect makes one of the largest risks of sodium cooled fast reactor (SFR) under unprotected severe accidents. The sodium void reactivity effect can be reduced by setting an upper sodium plenum and reducing the core height-to-diameter ratio (H/D). However, both methods bring significant cost to the internal breeding, due to a higher leakage of neutrons under normal operation. In this paper it is found that to bring the whole-core sodium void reactivity down to zero, the H/D must be as low as 0.15 approximately under the existence of an upper sodium plenum at the height of 40 cm. Such a design results in a fast drop of the burnup reactivity, as well as a low breeding ratio, a low regeneration ratio, and the decreasing of the fissile mass. It can be concluded that in the integral fast reactor design a dilemma exists between the high internal breeding and the low sodium void reactivity effect. This paper suggests that the integral fast reactor should focus on the breeding characteristics and thus a high efficiency of the utilization of uranium resources, leaving the sodium void reactivity to be incorporated into the overall design of the reactor safety features.

Physical calculations of reactor cores are fundamental for reactor core design and nuclear safety analysis. The second generation of core calculation theory and methods based on advanced component homogenization theory and modern coarse grid block methods are commonly used in reactor core physics calculations. However, due to the fact that the two-step method of component homogenization does not accurately provide the grid rod power, the modified two-step method of cell homogenization based on the pin-by-pin homogenization theory of core calculations has gradually become a research hot spot in core calculations. Compared with the two-step method of component homogenization, the pin-by-pin calculation scheme only carries out the homogenization calculation for each cell in the component, which preserves the non-uniformity of different cells in the component, reduces the approximation and assumption in the core calculation, and can calculate the core number more accurately, which is conducive to the safety analysis of the core. However, the SP3/GSP3 methods currently in common use for pin-by-pin calculations still suffer from limitations in balancing computational accuracy and efficiency. In this regard, this paper aims to establish a core calculation method named quasi-diffusion theory which considers both computational efficiency and computational accuracy. First, the 3D quasi-diffusion equation was derived and established from neutron transport theory. Unlike the traditional diffusion equation, the formulation of the quasi-diffusion equation did not introduce a first-order approximation for the neutron angular flux, and the concept of the Eddington factor was introduced to deal with the leakage term of the neutron transport equation. The 3D quasi-diffusion equation was then formulated. In addition, a numerical solution model for the quasi-diffusion equation was developed by referring to traditional numerical solutions of the diffusion equation such as the transverse integral equation and using the nonlinear iterative cross section method. Second, since the Eddington factor was the key parameter in solving the quasi-diffusion equation, the solution of the quasi-diffusion equation depends on whether the Eddington factor was exact or not. In this paper, the Eddington factor was regarded as the homogenization parameter similar to other small group sections. The solution was obtained using Serpent, a modified version of the Monte Carlo program. Finally, several cases including the whole core model and the color-set assembly model were employed to validate the method, and the results were compared with the traditional diffusion and Monte Carlo reference solutions. By comparing the numerical output results under each model, the results show that for reactor cores with complex structures and strong heterogeneity, the accuracy of quasi-diffusion calculations is significantly better than that of traditional diffusion calculations, and the computationally efficient of the two methods is similar. In summary, the quasi-diffusion equation approximation, as a nonlinear method to approximate the neutron transport equation, is a computationally efficient and accurate method. It has great promise for new core calculations with strong neutron anisotropy and complex neutron energy spectrum.

Multi-Radar Collaborative Surveillance (MRCS) technology enables a geographically distributed detection configuration through the linkage of multiple radars, which can fully obtain detection gains in terms of spatial and frequency diversity, thereby enhancing the detection performance and viability of radar systems in the context of complex electromagnetic environments. MRCS is one of the key development directions in radar technology and has received extensive attention in recent years. Considerable research on MRCS has been conducted, and numerous achievements in system architecture design, signal processing, and resource scheduling for MRCS have been accumulated. This paper first summarizes the concept of MRCS technology, elaborates on the signal processing-based closed-loop mechanism of cognitive collaboration, and analyzes the challenges faced in the process of MRCS’s implementation. Then, the paper focuses on cognitive tracking and resource scheduling algorithms and implements the technical summary regarding the connotation characteristics, system configuration, tracking model, information fusion, performance evaluation, resource scheduling algorithm, optimization criteria, and cognitive process of cognitive tracking. The relevance between multi-radar cognitive tracking and its system resource scheduling is further analyzed. Subsequently, the recent research trends of cognitive tracking and resource scheduling algorithms are identified and summarized in terms of five aspects: radar resource elements, information fusion architectures, tracking performance indicators, resource scheduling models, and complex task scenarios. Finally, the full text is summarized and future technology in this field is explored to provide a reference for subsequent research on related technologies.

Coal seam mining causes deformation, fracture and migration of overlying rock, further leading to the surface subsidence and ecological damage, which are the main manifestations of mining damage.Quantitatively characterize mining damage is the key to analyzing the stability of surrounding rock, designing mining parameters, and the premising of roadway support parameters.According to the finite element and discrete element simulation methods commonly used at this stage, this paper proposes a quantitative index(damage degree)to characterize mining damage: the proportion of zone plastic volume and the proportion of contact fracture length(number).On this basis, this study carried out the optimization of high-intensity mining parameters of the western mining area, the stability analysis of the coal pillar under the condition of mining and water immersion, and the progressive damage characteristics analysis of the roadway surrounding rock in the water-filled fault structure area by using the damage degree index.The quantitative relationship between the damage degree of the overlying rock and the mining parameters is obtained, which can realize the reasonable optimization of the mining parameters.This paper revealed the progressive damage characteristics of mining water immersion in coal pillars.We deemed that there is a danger of water seepage in the mined-out area as a water storage area under the existing coal pillar conditions.This study quantified the damage distribution characteristics of the surrounding rock in the roadway in the water-filled fault structure area, and proposed the corresponding? solution of dredging the fault through the roof aquifer, grouting reinforcement of the original fault fracture and strengthening the support.By comparing with common indicators such as the height of the water-conducting fracture zone and the width of the plastic development of the coal pillar, this research found that the damage degree indicators are more sensitive to the characterization of mining damage, and could realize continuous mining damage characterization.

The study of the transient electromagnetic detection device with small sized coil and easy installation underground will offer new insights into the real-time dynamic exploration and forecast water-bearing structure in excavation roadway.By drawing on the full-space transient electromagnetic theory, this paper adopted the three-dimensional time-domain finite element method for numerical simulation to explore the characteristics of the secondary field response obtained by small coil excitation and the transient electromagnetic response received by the magnetic core coil.This study constructed a geological-geophysical model of the water-bearing fault in front of the roadway excavation working face, studied the transient electromagnetic response characteristics of the small coil device for the water-bearing fault, and compared the effects of small coil and conventional coil in advance detection.The study shows that : ①the decay law of the induced electric potential generated by the small coil source excitation is the same as that of the induced electric potential generated by the conventional transmitting coil with time, ②the magnetic core coil can effectively improve the induced signal strength, ③the application of both the small coil device and the conventional coil device can effectively explain the distribution range of the low resistance area, ④the detection results match the verification results of the roadway excavation.Combined with the underground field test, this paper verified the applicability and effectiveness of the small coil device applied to mine transient electromagnetic method advance detection.

This paper proposed a new method for the determination of chlorine in coal by Eschka's mixture decomposition-ion chromatography so as to satisfy the needs of determining chlorine content in coal samples in large batches in coal exploration, coal production and processing industries.Specifically, this paper improved the sample pretreatment steps and determined the experimental parameters.The detection limit of the method was 0.001 7 %, the relative standard deviations of ten parallel determinations of three actual coal samples were in the range of 1.08 % ~3.92 %, the recoveries of six spiked determinations were in the range of 98 % ~104 %, and the results of the three standard coal samples were all within the guaranteed values.Results showed that the detection limit of the method was lower than that of the national standard method, and the precision and accuracy met or exceeded the national standard method.The determination of chlorine in coal by Eschka's mixture decomposition-ion chromatography has the advantages of simple operation, low cost and high determination efficiency and could be widely applied in the batch determination of a large number of samples.

Baked foods with a huge market scale play an important part in people's daily diet, and the market scale maintains a trend of rapid growth. The quality of baked foods is affected by many factors, such as raw material composition and processing conditions, so understanding the factors affecting the quality of baked foods is of great significance to process and produce high-quality baked foods. This paper reviewed the effects of fermentation conditions, processing conditions, and raw material composition on the quality of baked foods, and it also involved research on functional baked foods with the addition of special nutritional ingredients or low / no sugar content. These new types of baked foods are more in line with the current people's pursuit of the concept of nutritious and healthy diet. This paper could provide the reference for the design and production of high-quality baked foods, and promote the development and upgrading of the baked food industry.

In this paper, the overall development of electromagnetic heating food technology and even electromagnetic cooking technology was analyzed from multiple perspectives by means of literature date summary, and questionnaire survey analysis. This paper focused on the main components and functions, technical elements, core technical indicators and research hotspots of electromagnetic heating food equipment, and the current overall research situation of electromagnetic cooking food technology was also summarized and analyzed. For the commercial electromagnetic cooker products, this paper summarized and analyzed the market application situation and main use problems of electromagnetic cooker based on the questionnaire survey analysis method. Finally, based on the current situation of increasingly prominent problems of electromagnetic cooking products, the future development suggestion of standardizing market order and improving technology foresight was pointed out.

Geological reference material is a primary standard to ensure the accuracy of geological sample analysis results. After more than 40 years of development, China has developed and certified thousands of geological reference materials covering different media such as rock, ore, soil, sediment, organism, and water. China’s metrological management department divides the certified reference material into two classes according to the classification class, the first-class reference material (GBW) and the second-class reference material [GBW(E)]. According to their attributes and application fields, they are divided into 13 categories[6-7], and the geological reference materials belong to the seventh category [GBW07 and GBW(E)07]. It can be seen from the National Sharing Platform for Reference Materials (https://www.ncrm.org.cn) that by the end of the 13th Five-Year Plan, the total number of geological reference materials approved by the State Administration for Market Regulation is 1013, including 718 first-class certified reference materials, and the amount of first-class certified reference materials ranks first in the 13 categories (Fig.1). Geological materials are the most important and basic raw materials in the development of human society, with various types, complex components, and large differences in component content. It is because of the complexity of geological materials and the demand for reliable quantitative analysis that thousands of geological reference materials have been developed. Some reference materials developed by some industrial geological agencies are classified into other categories in classification management, such as isotope reference materials belonging to the fourth category, biological composition reference materials belonging to the tenth category, coal reference materials belonging to the eleventh category, these reference materials are widely used in related geological work, and in this paper they will be classified as geological reference materials. To systematically grasp the development status of geological reference materials in China, the first-class geological certified reference materials are comprehensively sorted, and are divided into six categories according to the type of matrix, property value and application scope: basic, ore, marine, environment, energy and special purpose (Table 1), and the development situation of each type, matrix characteristics and fixed value index respectively are summarized. On the basis of summarizing the results, on one hand, the main problems existing in the application of geological reference materials and the causes of these problems are analyzed. On the other hand, the detailed technical problems that may affect the uncertainty in the process of homogeneity, stability and characterization are discussed, and the views and suggestions are expounded. In this paper, the first-class geological certified reference materials are divided into the following six categories to summarize the development of each type: (1) 260 basic geological reference materials have been developed, the type of matrix including rock, soil and river sediments. The characteristic components of the certified value are generally 70 elements and compounds, which are mainly used as monitoring standards for sample analysis in basic geological surveys and research. (2) 272 ore geological reference materials have been developed, including precious metal ore, metal ore, single mineral, and non-metallic ore. The specific mineral types are shown in Table 1. There are generally 20 property values, which are the main technical indicators in mineral exploration. They are mainly used as a monitoring standard for geological exploration, mineral processing and smelting, comprehensive utilization, commodity inspection and trade amongst other fields. (3) 16 marine geological reference materials have been developed, including marine sediments and marine minerals. The specific samples include 10 marine sediment reference materials namely, 1 near sea, 1 Yellow Sea, 2 South China Sea, 1 East China Sea, 3 deep Pacific Ocean, 1 Antarctic Ocean and 1 Arctic Ocean. Six marine mineral reference materials are three polymetallic nodules and three ocean cobalt-enriched crusts. The characteristic composition of the certification value is the same as that of the basic geological reference material, but slightly less, generally 51-71 kinds. This is a necessary chemical composition measurement standard for marine sediment measurement and marine mineral resource survey and research. (4) 101 standard materials for environmental geology have been developed, including the available state of soil elements, the form of soil and sediment elements, the valence state of groundwater elements, the extractable state of soil elements, biological inorganic elements, organic pollutants in soil and sediment and other reference materials. The characteristic components of the matrix and certified values are the total amount of inorganic elements in biological samples, the available states, and forms of elements in soil and sediment, the valence states of elements in water and organochlorine pesticides, polychlorinated biphenyls, and polycyclic aromatic hydrocarbons in soil and sediment. This kind of reference material provides analytical quality monitoring standards for land quality geochemical surveys and evaluation, regional ecological geochemical evaluations, multi-objective geochemical surveys and detailed surveys of soil pollution. (5) 23 energy geological reference materials have been developed. The property values of oil-generating rock reference materials are organic carbon, pyrolysis hydrocarbon S2, pyrolysis peak temperature Tmax, and chloroform asphalt “A”. The property values of coal reference material are calorific value, ash, volatile matter, total sulfur, carbon, hydrogen, nitrogen, true relative density and phosphorus, chlorine, fluorine, and arsenic. The property values of the reference materials of highly evolved hydrocarbon source rock are pyrolysis hydrocarbon S2, pyrolysis peak temperature Tmax, and total organic carbon TOC. This is the monitoring standard for the exploration, evaluation and rational utilization of energy and mineral resources. (6) 129 reference materials for special purposes have been developed, including 20 synthetic reference materials for emission spectroscopy and 4 synthetic reference materials for X-ray fluorescence spectroscopy analysis. The property values are 28-29 inorganic chemical elements. There are 38 isotope reference materials, and the property values of those include isotope abundance and abundance ratio. There are 35 electron probe reference materials, and the property values are generally two principal components of their minerals. There are 15 reference materials for phase analysis, and the property values are the corresponding main phase. There are 5 soil limit water content reference materials, and the property values are 10mm liquid limit, plastic limit, and plastic index. There are 12 soil pH reference materials, and the property values are pH. It can be seen from the classification and summary that the geological reference material matrix in China is rich in types and quantities, which establishes an influential quality monitoring system for geological sample analysis, ensures the reliability and consistency of geological sample test data, and significantly improves the comparability and scientific value of relevant data. At present, there are still some problems in the application and development technology of a large number of geological reference materials. The problems are discussed and analyzed, hoping to draw attention to improving the value determination class of geological reference materials. In the aspect of application, the specific problems existing in different types of geological reference materials and their causes at the present stage are analyzed and development suggestions are proposed, according to the work needs of current mineral resources, international cooperation, marine strategy, ecological civilization and other fields. In the aspect of development technology, some detail technologies which may affect the value determination class in the process of homogeneity, stability and characterization are analyzed. In the aspect of development technology, some detail technologies which may affect the setting in the process of homogeneity, stability and value setting are analyzed. The test method of homogeneity and the evaluation method of stability uncertainty are discussed. Suggestions are made for the uncertainty evaluation method of unexamined elements for homogeneity test and control limit of relative extended uncertainty. 1. Three problems existing in the current application of geological reference materials are analyzed: (1) The quantity of some types of reference materials developed is small, the gradient distribution of characteristic values is insufficient, and the matrix type is simple. For example, the amount of marine geology, micro-area analysis, energy and mineral resource reference material development is small. The ore-forming elements of key metal ore reference materials are mainly low content, lacking rich ore grade or higher content grade. The matrix types of the samples of organic pollutant reference materials are only soil and sediment, and the property values are only organochlorine pesticides, polychlorinated biphenyls, polycyclic aromatic hydrocarbons and other compounds, and the matrix types and target compounds are few. The main reasons for these problems are difficulty in obtaining samples, little working demand, difficulty in ensuring the uniformity and stability of the sample preparation technology, large error of analysis technology unable to determine the value. (2) There are many components in the geological reference materials with mature development technology that have no certified values. The reasons of low element content and test interference are mainly analyzed. (3) At the current class of analytical technology, there is only one measurement method for several elements, and for some elements, with the widespread application of modern instrumental analysis technology, the optional measurement method is gradually becoming singular. 2. The detail technology of four aspects in the development of reference material is discussed: (1) Uniformity testing method. XRF is a widely used measurement method for the uniformity test of geological standard materials due to its high testing precision. However, due to its large sample size, XRF cannot meet the requirements of minimum sample size. Since the release and implementation of China National Technical Specification for Measurement “General and Statistical Principles for Characterization of Reference Materials” (JJF1343) in 2012, the uniformity of reference materials was tested by ICP-MS and ICP-OES under 0.1g weighing sample[24-30]. The measurement precision of these two methods is not as good overall as that of XRF, and the accuracy of individual elements is poor, which may cause the numerical value to be too large when calculating the uncertainty introduced by uniformity, thus affecting the reasonable evaluation of the uncertainty of property value. For this reason, some scholars[34-35] improved the XRF sample preparation device, studied the accuracy and precision of the method under 0.1g weighing sample, and verified the application effect for uniformity testing. However, only 10 major components in the reference materials of soil and stream sediments were tested under 0.1g weighing sample, while the reference materials of other matrix types and other trace elements, especially heavy elements, have not been studied and tested. Therefore, the feasibility of the XRF method with a sample size of 0.1g still needs to be verified. (2) Uncertainty calculation method for elements without uniformity test. The composition of geological materials is complex, and its reference substances generally have multiple attribute values, and the content of each component is greatly different, so it is usually difficult to test the uniformity of all attribute values. According to the provisions of JJF1646—2017, the characteristic of representative and less homogeneous should be selected for uniformity evaluation. The uncertainty of the untested elements can be evaluated according to the concentration and geochemical properties with reference to the uncertainty introduced by the tested elements. However, the exact calculation method was not specified. An evaluation method that considers both element properties, content and test methods (Table 2) is presented here. The specific calculation method is to multiply the relative uncertainty (Ur) of the uniformity of the detected element by the standard value μ of the undetected element and take it as the uncertainty component ubb of the undetected element. (3) Evaluation method of stability uncertainty. At present, trend analysis method is generally used to evaluate the stability uncertainty (us) of geological reference materials, and the calculation formula is us=s(b1)·t. It can be seen from the formula that the longer the stability monitoring time, the greater the stability uncertainty introduced. The stability uncertainty data of several reference materials were compared and determined to be the main contribution to the total uncertainty, which is inconsistent with the long-term observation of the stability of the geological reference materials. Therefore, this calculation method is not suitable to evaluate the uncertainty introduced into the stability of geological reference material. Meng et al.[42] suggested using the analysis of variance to calculate, and the comparative analysis showed that us was still the main contribution to the total uncertainty. Wang et al.[43] used range method to calculate us, but the application of this method in geological reference materials has yet to be verified. In conclusion, the reasonable evaluation of stability uncertainty of matrix reference materials with more test error sources needs to be studied further. (4) Control limits for relative extended uncertainty. The determination of the property value of geological reference materials usually has certain control requirements for relative extended uncertainty (Urel), but these control limits are rarely introduced in the public information of the reference material. It was not until the specification JJF1646 published in 2017 that Urel was required in principle. Urel is the embodiment of the quality of property value data. Urel control limits in Table 3 are proposed on the basis of the principle requirements of JJF1646—2017 by referring to the control limits in the development of existing reference materials and the analysis of different types of geological reference materials. In the process of development, the developer also needs to comprehensively consider the matrix condition, setting index, element content of the sample and formulate reasonable Urel control limits of uncertainty in combination with the current analysis technology class, to obtain accurate and reasonable property value and uncertainty.

The overweight or obese population in sub-health status and the aging population in China are increasing year by year. The intracellular level of nicotinamide adenine dinucleotide (NAD+) decreases dramatically with age and obesity. NAD+ is the key target of cellular energy metabolism and cell function regulation, which affects senescence. Therefore, improving physiological functions and delay aging by supplementing NAD+ precursors has become a hot topic of current research. β-Nicotinamide mononucleotide (NMN) is an intermediate metabolite of NAD+ in animals, and it is also the most direct and efficient NAD+ supplement precursor at present. However, NMN has complex effects on the physiological functions of various organs, the results of animal tests are not consistent with those of human clinical tests, and the optimal dosage has not been determined. This paper summarizes the results of recent animal and human clinical tests of NMN aiming to explore the effects, mechanisms, doses and adverse reactions of NMN supplementation on animal and human physiological functions. Through this paper, we hope to provide ideas for future research and application of NMN.

Protein gels are three-dimensional protein networks with high moisture content, which have been widely applied in several fields such as food, medicinal, and industrial sectors. Gel texture can be improved by adding dietary fiber due to its good physical, chemical and physiological properties, which has become the focus of attention of researchers. In order to better understand recent progress in research on dietary fiber-protein composite gels, this paper focuses on the classification, structure and functional characteristics of dietary fiber, and summarizes the current state of knowledge on the effect and mechanism of dietary fiber on the characteristics of protein gels. Moreover, it gives an overview of the application of fiber-protein gels in the fields of food and medicine and predicts future development directions. This paper will provide a basis for the preparation and application of fiber-protein gels.

Melatonin, a trace efficient natural plant signaling molecule, has been widely reported in plant growth and development, abiotic stress, and postharvest preservation and other aspects. In recent years, melatonin has been found to play a positive role in inducing disease resistance in fruits. This paper describes the effect of melatonin on pathogens in vitro and in infected fruits, with a focus on the mechanism by which melatonin induces fruit resistance to invasive diseases. Furthermore, this paper reveals that melatonin and plant signal transduction pathways constitute a regulation network to mediate disease resistance responses in fruits. We conclude this paper with an outlook on future research directions in order to provide a theoretical reference for further research on the mechanism by which melatonin induces disease resistance.

The mass analyzer based on quadrupole field theory, including quadrupole and ion trap, control and screen ions by a non-magnetic, alternating electric field, which was the first proposed by Professor Paul in 1953. Since the birth of quadrupole, ion trap and other related mass spectrometry technologies have been developed relatively maturely, which have made a significant impact and contribution to mass spectrometry. This paper deduced and interpretd the complete physical and mathematical formulae of the design and generation process of the quadrupole field. The process of obtaining the potential distribution of the quadrupole field, the obtaining process of boundary conditions such as electrode shape and voltage on the electrode, and the process of deducing the quadrupole structure and ion trap structure according to the potential distribution of the quadrupole field were discussed. In the above processes, for the purpose of binding ions, a general potential (Prof. Paul called it “allgemeinste potential” in German) distribution equation was obtained by introducing a simple harmonic motion model. And then, according to the basic laws of electromagnetic field and Maxwell’s equation, the condition of zero electric field divergence was introduced. Based on this, through the discussion of the two simplest solutions and boundary conditions, the structure and field distribution equations of the quadrupole and the ion trap were obtained, respectively. This content was an important supplement to the elaboration on the theory of quadrupole field mass spectrometry, which was helpful for a deeper understanding of basic principles of quadrupole field. At the same time, this paper provided a potential mass analyzer design method. Firstly, the design began with the conception of the state of ion motion, and then a force that could control the movement of ions according to the idea was found. Secondly, combined with the basic laws of electromagnetic fields, the general equation and its limiting conditions for the potential distribution that could form this force were obtained. Thirdly, according to the easy-to-operate settings in practice, the boundary conditions of the field (such as electrode shape, electrode voltage, etc.) were obtained, and the intermediate variables in the general equation were replaced with these operable physical parameters. At last, according to the potential distribution equation, the ion motion equation was calculated, and the mathematical relationship between the mass-to-charge ratio and the controllable physical parameters was found. And finally, a mass analysis method for controlling and separating ions was obtained. This kind of design method has important reference significance for theoretical research and original innovation research related to mass spectrometry.

[Introduction] Hydrogen energy is characterized by the advantages of wide sources, high calorific value, storability, no pollution, and zero carbon emissions. It has become a zero-carbon clean energy with great development potential. At present, mature hydrogen production technologies are mostly based on large-scale hydrogen production, which can hardly meet the demand for compact portable hydrogen production equipment in some important occasions. [Method] In order to meet this demand, this paper first analyzed and summarized the characteristics, advantages and disadvantages, and development trends of the existing large-scale hydrogen production technologies. Besides, considering that ammonia has the advantages of easy liquefaction and storage and high hydrogen content and is an excellent carrier for hydrogen, this paper further proposed the technical idea of using porous medium burner with adiabatic flame temperature to produce hydrogen by ammonia reformation and carried out a systematic analysis from the aspects of technical feasibility, research methods and research contents. [Result] Based on the existing research results of porous medium burners, the feasibility of using porous medium burner for ammonia reforming to produce hydrogen is analyzed. On this basis, the research methods, research contents and technical routes of ammonia reforming for hydrogen production by using porous medium burner are summarized and prospected. [Conclusion] Obtaining the optimal design for the overall structure, microchannel, and reaction carrier structure of the porous medium burner and developing non-precious metal catalyst materials with good performance and low cost will be the main research directions of the porous medium burner for hydrogen production by ammonia reforming. The research in this paper can provide some theoretical and technical support for the development of the technology of hydrogen production by ammonia reforming with porous medium burner.