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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.

[Introduction] In order to improve the problem of traditional proportion integration differentiation (PID) controllers overly relying on the mathematical model of the controlled object in the temperature control in hydrogen production by water electrolysis, this paper studies the application of fuzzy internal model control in the temperature control in hydrogen production by water electrolysis, and provides the design process of the fuzzy internal model controller. [Method] Firstly, the importance of temperature in the process of hydrogen production by water electrolysis was analyzed, and some temperature control strategies commonly used in hydrogen production by water electrolysis and their advantages and disadvantages were listed. Then, internal model control theory and fuzzy theory were introduced, and a design method for a fuzzy internal model temperature controller, which was used to achieve precise temperature control in hydrogen production by water electrolysis, was proposed based on these two theories. Finally, simulation verification experiments were conducted. [Result] The results show that the fuzzy internal model control method used in this paper has better control quality in response speed, anti-interference, and robustness compared to the PID control method, solving the problem of traditional PID controller algorithms overly relying on the mathematical model of the controlled object. [Conclusion] The control algorithms used in this paper are correct and effective, and can be applied to the temperature control in hydrogen production by water electrolysis.

[Introduction] As wind-solar hydrogen production projects expand in scale and number, there is a growing demand for the design, equipment selection, and economic comparison of green hydrogen production systems. This paper, based on the design experience of multiple similar projects, extracts the typical design of wind-solar coupled hydrogen production system and provides the design selection. [Method] This paper introduced design scheme of wind-solar coupled hydrogen production from the aspects of wind-solar hydrogen storage capacity configuration scheme, electrolysis hydrogen production equipment performance and rectifier comparison, hydrogen and oxygen separation and purification system design, and green hydrogen market and economy analysis. [Result] Capacity configuration can be optimized according to the developed design software through constraint conditions. alkaline electrolysis equipment is the preferred choice for hydrogen production，while proton exchange membrane (PEM) electrolysis equipment can be used for small-scale engineering demonstration. Both thyristor and insulated gate bipolar transistor (IGBT) power rectifiers have their own advantages, and IGBT rectification is gradually being applied in engineering practice. For saving investment, separation and purification can be optimized according to the scale of the project. The market for green hydrogen is huge. As fossil fuel prices continue to rise and the costs of wind-solar coupled hydrogen production systems decrease, coupled with its eco-friendly characteristics, green hydrogen has already become economically competitive. [Conclusion] The wind-solar coupled hydrogen production project is still in the initial demonstration stage, which requires equipment technology progress, design scheme optimization and government policy support to promote the development of green hydrogen industry.

[Introduction] The increasingly high proportion of renewable power sources raises higher requirements for the safe and stable operation of the power system and the reliable supply of electricity. Hydrogen and electricity are complementary in many scenarios of energy consumption. Green hydrogen produced by renewable power will become an important component of the new energy system, which can also facilitate the construction of the new power system. Recently, green hydrogen demonstration projects in China and abroad are burgeoning. However, the typical modes and future development trends are not clear. This paper aims at clarifying the typical modes for green hydrogen projects and providing solutions to issues faced by the large-scale application and the full play of power-hydrogen coupling. [Method] In this paper, the existing green hydrogen demonstration projects in China and abroad were systematically analyzed. The characteristics of the three groups were studied, based on which, the development trends of green hydrogen demonstration projects were proposed. Then, the key problems and challenges were analyzed, and key measures were proposed. [Result] Through the study, the green hydrogen projects are grouped into three categories, which are power-hydrogen coupling projects on the distribution/micro-grid side, large-scale hydrogen production near renewable basis and utilization projects and hydrogen-based flexible adjustment projects. Key issues lying ahead include the lack of coordinated planning between the power and hydrogen system, the less economic competitiveness of green hydrogen and some of the key technologies, equipment and materials are dependent on imports. [Conclusion] To solve these issues and promote the development of green hydrogen projects, the coordinated planning of power and hydrogen system should be strengthened, formulated a set of supporting policies, improved the relevant market mechanisms, accelerated the standards and deployed some essential projects.

[Introduction] Hydrogen energy plays an important role in the construction of a new energy system due to its extensive sources, convenient storage and transportation, and efficient utilization. This paper systematically analyzes the development strategies of the hydrogen energy industry in the United States and European Union, and combines with the actual development of Chinese industry, and gives specific policy suggestions for the development of the hydrogen energy industry. [Method] The successful experience of hydrogen industry development in the United States and Europe was summarized by combing and analyzing the relevant policies, strategic planning and typical practices of hydrogen energy development in the two major economies. [Result] Based on the current development status of the hydrogen energy industry in our country, this paper puts forward a number of targeted policy recommendations, including strengthening the top-level design to further improve the hydrogen energy industry development policy system; strengthening the guidance of scientific and technological innovation, and attaching importance to the innovation and breakthrough of core technologies in key links of hydrogen energy; expanding the diversified application of hydrogen energy and building a collaborative ecology; attaching importance to international cooperation and taking an active part in the formulation of international rules and standards. [Conclusion] The policy recommendations mentioned in the article can provide reference for relevant departments and industries, so as to further improve the development quality and speed of the hydrogen energy industry.

Kudingcha (Ligustrum robustum (Roxb.) Blume) is widely used as a traditional medicinal and culinary plant of great economic value. It has a long history of use as an ethnic medicine and an alternative to tea in Guizhou, Yunnan and Sichuan provinces of China, and has attracted much attention in recent years. The chemical composition of kudingcha (Ligustrum robustum (Roxb.) Blume) is complex, from which phenylpropanoids, phenylethanoids, monoterpenes, iridoids, flavonoids and volatile oils have been isolated. It has a wide range of pharmacological effects, including lipid-lowering, antioxidant, antiviral, antibacterial, anti-inflammatory, immune regulatory and anticancer activities. However, in recent years, there are few systematic reviews on Ligustrum robustum (Roxb.) Blume, even though it is only mentioned in the reviews on Ligustrum plants or kudingcha, which is not conducive to the standardized research, development and utilization of kudingcha (Ligustrum robustum (Roxb.) Blume). This paper comprehensively summarizes recent research on the composition, pharmacological activity and quality control of kudingcha (Ligustrum robustum (Roxb.) Blume) with focuses on the structural features and pharmacological mechanism of its characteristic components. This paper will provide a theoretical reference for the preparation, separation, structure identification and pharmacological research of the characteristic components of kudingcha (Ligustrum robustum (Roxb.) Blume).

ObjectivesThis papers aims to analyze the impact resistance of honeycomb structure with different Poisson's ratio. MethodsBased on the explicit dynamic finite element method, this paper analyzes the dynamic mechanical properties of honeycomb structures with different Poisson's ratios under in-plane impact load, and explores the influence laws of Poisson's ratios on their impact resistance. Three typical honeycomb structures with negative/zero/positive Poisson's ratios (reentrant hexagon, hexagon and semi-reentrant hexagon) are selected, their geometric parameters are changed to give them the same relative density and different Poisson's ratios (−2.76 – +3.63), and their dynamic mechanical properties under low/medium/high-speed dynamic displacement loads are analyzed. ResultsThe results show that the zero Poisson's ratio semi-reentrant honeycomb structure has the best structural stability without transverse deformation under compression deformation; without structural instability, the platform stress has little correlation with the Poisson's ratio; and the compact strain and total energy absorbtion increases with the absolute value of the Poisson's ratio. Negative Poisson's ratio honeycomb structures with large t/l and small θ are suitable for applications with high platform stress (strong deformation resistance), and negative Poisson's ratio honeycomb structures with small t/l and small θ are suitable for high total energy absorbtion applications, while zero Poisson's ratio semi-reentrant honeycomb structures are suitable for applications with high platform stress (strong deformation resistance). ConclusionsThis study can provide references for the type selection and geometric parameter design of side impact honeycomb structures.

Objective This paper carries out an experimental study of a multi-function dirllship model with moonpool structure in towing tank, aiming at analyzing the effects of the moonpool structure on the ship resistance in open and closure condition.MethodsTaking a dirllship as the research object, the ship motion response in regular and irregular waves is investigated. The resistance of the ship in hydrostatic water and waves is measured with tension sensors, and the acceleration characteristics of the bow, midship and stern are analyzed by acceleration sensors.ResultsThe results indicate that hull resistance under light load conditions is greater when open moonpool, while hydrostatic water resistance with closed moonpool is greater under design load conditions. The closed moonpool in regular waves reduces stern acceleration by 58.2%, bow resistance by 46.7% and heave response by 41.8%. The peak of resistance at the bow in irregular waves is about ten times higher than that at the stern, and the peak of resistance occurs more often when the moonpool is open at the same time.ConclusionsThe experimental study shows that the difference in load conditions changes the waterplane area and affects the hull resistance in hyrostatic water. In contrast, the closure of the moonpool not only reduces acceleration and resistance, but also improves surge and heave. As such, this paper can provide references for the structural design of drillships with moonpools.

Laser loading compression is one of the main research topics in the field of inertial confinement fusion. In order to simulate and explain the experimental phenomena of materials under high strain rates and pressures generated by laser shock, the submicron requirements for the adhesive layer thickness between the target multilayer materials in the state equation experiment were proposed in the physical experiments. Compared with the existing recombination methods, a novel adhesive recombination was reported in this paper. The poly glycidyl methacrylate (pGMA) film was prepared by initiating chemical vapor deposition method, and the liquid phase activation method was used to activate and cure the solid adhesive film. The submicron lossless bonding recombination of the state equation test target could be realized. In the activation process of pGMA film, the liquid phase activation method proposed in this paper will greatly improve the connection strength of multilayer materials without changing the thickness of the adhesive layer, which has not been reported. The thickness and morphology of the pGMA film were characterized, and the influence of process parameters on the film thickness was discussed. The deposition rate of pGMA film is about 10 nm/min in this paper. The white light confocal technology was used to indirectly measure the adhesive layer thickness of some nanoglue bonding samples. For the materials such as hydrocarbon and high-density carbon, the adhesive layer section of the nanoglue bonding samples was prepared by means of metallographic sample preparation combined with ion beam etching, and the adhesive layer thickness was directly characterized by scanning electron microscopy. The above results show that the adhesive layer thickness of the nanoglue bonding samples is submicron. And the thinnest adhesive layer of the nanoglue bonding samples is only 300 nm. The morphology of adhesive layer about the nanoglue bonding samples was characterized by optical microscope. The nanoadhesive layer connected the multilayer materials together evenly and seamlessly, and there were no gaps and air bubbles between the samples. The nanoglue bonding method reported in this paper has many advantages, such as precise control of the adhesive layer thickness, greatly improving the connection strength between the multilayer samples of the target in the equation of state experiment, realizing the precise assembly of the target with small size and complex configuration. This method will provide technical support for the improvement of the precision of laser loading compression physical experiment and the accurate interpretation of experimental results.

Building layover detection is a crucial step in the 3D Synthetic Aperture Radar (SAR) imaging process in urban areas. It affects imaging efficiency and directly influences the final image quality. Currently, algorithms used for layover detection struggle to extract long-range global spatial characteristics and fail to fully exploit the rich features of layover in multi-channel SAR data. To address the issue of insufficient accuracy in existing layover detection algorithms to meet the requirements of urban 3D SAR imaging, this paper proposes a deep learning-powered SAR urban layover detection method that combines the advantages of the Vision Transformer (ViT) model and Convolutional Neural Network (CNN). The ViT model can efficiently extract global and long-range features through a self-attention mechanism, whereas the CNN has strong local feature extraction capabilities. Furthermore, the proposed method in this paper incorporates a module for investigating inter-channel layover features and interferometric phase layover features based on expert knowledge, which improves the accuracy and robustness of the algorithm while effectively decreasing the training pressure on the model in small-sample datasets. Finally, the proposed algorithm is tested on a self-built airborne array SAR dataset, and experimental findings revealed that the proposed algorithm achieves a detection accuracy of >94%, which is significantly higher than other layover detection algorithms, completely revealing the effectiveness of this method.

Cyclic prefixes in joint radar and communication systems based on Orthogonal Frequency Division Multiplexing (OFDM) and low probability of interception lead to weak radar echo masking on the battlefield. To address this problem, a low probability of interception waveform design scheme based on Filter Bank Multi-Carrier (FBMC) with Offset Quadrature Amplitude Modulation (FBMC-OQAM) is proposed in this paper. Mathematical models for the FBMC joint radar and communication waveform, target detection probability, and communication channel capacity are established. Under the radar and communication performance constraints required by the system, a joint optimization problem of minimizing the total transmitted power of the system is designed, and the subcarrier and power allocation scheme are optimized. Furthermore, the proposed algorithm can realize adaptive transmission where the parameters of the transmitting waveform can be optimally designed for the next pulse by utilizing the measured values of the current signal and the channel state information. Moreover, the feasibility and advantages of FBMC as the radar signal are analyzed based on the average ambiguity function. Theoretical analysis and simulation experiments show that the power allocation scheme proposed in this paper can effectively reduce the total transmitted power of the system, to achieve low interception performance compared with the equal power allocation. The FBMC waveform can effectively reduce the sidelobes caused by cyclic prefixes, which improves the radar resolution and information rate.

During the confrontation of electronic systems, it is challenging to deal with the enemy’s comprehensive electronic weapons by simply combining electronic equipment, such as radar, communication, surveillance, and jammers. Hence, to meet the requirements of a modern war environment, the comprehensive integration of various electronic equipment is an inevitable trend. Radar and communication equipment, which are viewed as forward eyes and ears, are very similar in hardware structure and signal processing methods. In this regard, the organic union of these two is plausible. As a result, the Dual-Function Radar and Communication (DFRC) system has received a lot of attention, where integrated waveform design is one of the key scientific issues. The DFRC waveform primarily refers to the transmit waveform that realizes radar detection and information communication functions simultaneously in multiple dimensions, such as space, time, and frequency domains, through electromagnetic spectrum sharing. This paper provides a fundamental review of the radar-centric DFRC waveform design. Initially, this paper presents a brief overview of the radar-centric DFRC system’s application scenarios. Then, the progress of radar-centric integrated waveform design research is discussed. Finally, some closing remarks and potential future research directions are provided.

In order to reduce the occurrence of safety production accidents in coal mine industry, this paper combined the definition of safety behavior and unsafe behavior, behavior safety theory and MMEM system theory to put forward the standard definition of safety state of coal mine workers' behavior.According to the behavior influencing factors, this study established the coal mine workers behavior safety state evaluation index system, including 4 first-level indicators 21 secondary indexes.The Improved-AHP method, Entropy Weight method and variance coefficient method were adopted to determine the subjective and objective weights and weight combination.Taking one mine as example for analysis, this paper chose extension comprehensive evaluation method to construct the evaluation model. Results show that: For the coal mine industry, the defined-evaluation-improvement(D-E-I)model is universal.The empirical evaluation level is Ⅳ or "relatively safe".The evaluation results are in line with reality, and the model is scientific and practical.

The purification effect of coal mine groundwater reservoir on mine water mainly lies in the water-rock coupling between the rock mass and mine water.This paper systematically reviews the research methods of water-rock coupling in coal mine underground reservoirs, and presents the characterization methods of water quality and physicochemical properties of rock samples.It employs static simulation, dynamic leaching, cycle purification simulation and other tests to explore the purification regulation of mine water in coal mine underground reservoir, uses numerical simulation to obtain the selective adsorption trend of ions in the reaction process, and combines Piper three-line diagram, Gibbs model and correlation analysis to reveal the mechanism of water-rock coupling.The purification effect and research progress of suspended solids, specific ions and organic matter in coal mine underground reservoirs are discussed.The paper shows that underground reservoir of coal mine has a certain purification effect on mine water, and the purification effect of specific ions is mainly related to filtration and adsorption.Three research directions of coal mine underground reservoir purification technology in the future are proposed: ①developing large-scale and low-cost treatment technologies for underground mine water based on water-rock coupling purification, ②developing a "three-in-one" water quality control technology for coal mine underground reservoirs coupled with multiple water treatment technologies, and ③exploring the underground storage and resource utilization technology of concentrated salt wastewater for the future studies of water-rock coupling.

The problem of overlapping mineral rights of coal and gas is common in the Ordos Basin of China.The interaction will occur when coal and gas are mined simultaneously, so it is necessary to solve the synergistic mining problem to eliminate the accident potential.Considering that there are many constraints in the simultaneous exploitation of gas and coal, this paper proposed an energy control failure model by energy abnormal release and STAMP.This model explains the applicability of information transfer cycle and the energy control failure model.Then, through the analysis of gas-coal mining process, this paper established the interaction between the energy unit, barrier unit, and disaster-bearing body, and analyzed the characteristics of energy transfer and safety barrier interaction.Finally, by analyzing 9 kinds of accidental release scenarios, this study proposed the identification behavior methods and control measures to prevent gas-coal cross-mining accidents.

Faults are an important factor inducing mine safety accidents, and it poses difficulties on the identification of faults within 5 m of drop.Taking the Liupanshui coalfield of Guizhou province as the study area, this paper investigated the coalfield strata and carried out an on-site survey.It proposed a seismic physical model and used the unique velocity ratio of 1∶1.74 to realize the construction and analysis of small faults with a burial depth of 800 m, 1 000 m and 1 200 m and a drop of 5 m, 3 m and 1 m.This paper extracted a variety of seismic properties by seismic dynamics method to analyze small faults, and obtained the sensitivity of seven seismic properties to the characteristic response of small faults, including amplitude envelope, amplitude first derivative, and amplitude second derivative, and the correlation between seismic properties and drop was established accordingly.The results show that when the small fault drop of the coal seam is less than or equal to 5 m, there is a linear relationship with the traditional amplitude attributes, and a linear relationship with the seismic properties related to phase and frequency.There is high correlation between the amplitude envelope and the amplitude imaginary part, and low correlation between the instantaneous frequency, the amplitude first derivative, the cosine instantaneous phase, the amplitude second derivative and the amplitude envelope.

In recent years, China's cold chain logistics industry has entered a stage of rapid development. At the same time, with the increase of greenhouse gas emissions, green and low-carbon transformation has become a new feature and direction of high-quality and healthy development of the cold chain industry to meet the future development needs of China's low-carbon economy. In view of this, in order to ensure the scientificity of China's low-carbon cold chain logistics evaluation system, in this paper, 30 indicators from the four levels of energy transformation, technological innovation, economic efficiency, and national policy based on different relevant levels were first preliminarily determined, and finally 14 indicators for building China's low-carbon cold chain logistics development evaluation system through consulting experts and the possibility of data acquisition were determined. Data from 2017 to 2021 were selected to conduct a quantitative evaluation of the development level of low-carbon cold chain logistics in China. Firstly, the entropy weight method was used to analyze the weight and obstacle degree of different indicators to explore the impact of different indicators on the development of low-carbon cold chain logistics; Secondly, a weighted decision-making matrix was constructed based on the weights of different indicators, and the technology for order preference by similarity to ideal solution (TOPSIS) evaluation model was used to evaluate the development of low-carbon cold chain logistics in China from 2017 to 2021, in order to determine the development and changes of low-carbon cold chain logistics in China. The research results showed that among the 14 different indicators of the established evaluation system for the development of low-carbon cold chain logistics in China, the growth rate of the use of green packaging materials, the number of low-carbon technical papers published, the proportion of scientific research personnel, the growth rate of cold chain logistics demand for fresh agricultural products, and the reduction rate of hydrochlorofluorocarbon refrigerants account for a relatively large proportion, ranking in the top five, respectively reaching 0.1243, 0.1074, 0.1066, 0.0982, and 0.0716, accounting for more than half of the overall proportion. It has a significant impact on the development of low-carbon cold chain logistics in China. From 2017 to 2021, the development level of China's low-carbon cold chain logistics was scored from 0.1498 to 0.2359, with a year-on-year increase of about 57.5%, indicating that China's low-carbon cold chain logistics development level was relatively fast in the past five years. Although China's low-carbon cold chain logistics development has shown an overall upward trend, it is still in the development stage.

Compared with the advanced and sophisticated industrial production, agriculture and food production appear backward and sloppy, and agricultural production management methods are lacking. The fourth industrial revolution, represented by information technologies such as intelligent perception, Internet of Things, block chain, big data and artificial intelligence, has empowered traditional industries, and agriculture has stepped into a new digital, intelligence and even wisdom, which could provide a new opportunity to improve agricultural production management. Existing agricultural production management research is mostly limited to the study of concept definition, applicable theory and other issues. The development of information technology has built up a low-level Internet of Things with certain coverage, which brings some convenience, but cannot effectively support agricultural management and decision-making due to data silos, data waste, data abuse, data falsification and other thorny issues. From the perspective of top-level design and system management, this paper addressed the problems in the development of smart agriculture, conceptualized the characteristics of the event and natural event chains in the agricultural industry chain. This paper also proposed for the first time an event-correlation management approach and its wisdom strategy. The implementation of the event-correlation method included five aspects, including goal alignment, index systematization, asset linkage, process linkage and effect traceability. The application of the event-correlation management approach and its wisdom in the 5T management standard designation for Jilin rice brand building and the “six-step fresh rice precision control technology” innovation system of Wilmar rice industry have shown that it can improve the culture of rice cultivation, and systematically reduce losses to improve quality and increase economic benefits.

Resistant starch has the benefits in the regulation of intestinal flora, improvement of intestinal function, control of cholesterol levels and glycemic index. In recent years, the most concerned is the prebiotic effect of resistant starch. Fermented milk has been considered as the best carrier of probiotics and prebiotics. Adding type III resistant starch to fermented milk could not only improve the quality of fermented milk, but also enhance the functionality of fermented milk. This paper briefly introduced the relationships between resistant starch and prebiotics, and summarized the application of type III resistant starch in fermented milk. This paper also expounded the effect of type III resistant starch on the quality of fermented milk and its probiotic evaluation, which could provide reference for the application and development of type III resistant starch in functional fermented milk.

Food safety incidents caused by pesticide residues are threatening the life and health of people. At present, pesticide residues in food samples are miscellaneous, low and unknown to testing personnel and thus difficult to detect. Therefore, it is of great significance to develop high-throughput and non-targeted for the detection of pesticide residues in food samples. Chromatography-mass spectrometry has been widely used in the field of pesticide residue detection because of its advantages of high separation and identification efficiency as well as high-throughput and non-targeted nature. This paper summarizes the literature on high-throughput and non-targeted detection of pesticide residues in food samples by chromatography-mass spectrometry in the past 10 years. The current status of multi-pesticide residue detection in food samples is briefly described. Besides, this paper focuses on the application of chromatography-mass spectrometry in the detection of pesticide residues in food samples from the perspectives of the development of multidimensional chromatography and high-resolution mass spectrometry, the improvement of sorbent materials and sample pretreatment techniques, and the optimization of chemometric algorithms. Some suggestions for the problems existing in this field of research are put forward aiming to provide a new reference for the application of chromatography-mass spectrometry in the detection of multi-pesticide residues in food samples.

Condiments are necessary to improve the flavor of foods and are a major source of salt intake for people. Excess salt intake can be a health risk, but reducing salt can reduce the umami and taste of foods, thus reducing product quality. This paper reviews the technical strategies for salt reduction while ensuring saltiness and umami as well as their harmony. The salt reduction strategies include reducing the amount of salt, using salt substitutes and enhancing saltiness perception. The umami enhancement strategies include adding yeast extracts, umami peptides, umami amino acids and peptide derivatives. Besides, salt reduction and umami enhancement can be achieved by using lactic acid bacteria, Maillard reaction intermediates, flavor enhancers and taste-active peptides. The application of the salt reduction and umami enhancement strategies will promote the development of the condiment industry, but these strategies have the problems of insufficient basic research, few practical applications, narrow application scope and high production cost. At present, it is difficult to solve these problems. In this paper, the basic principles and characteristics of the strategies for salt reduction and umami enhancement in condiments and the current problems existing in this field of research are reviewed in detail. Future development directions are put forward in order to provide a reference for research on salt reduction and umami enhancement of condiments.

[Introduction] The paper proposes an energy consumption calculation method for prefabricated cabin type lithium iron phosphate battery energy storage power station based on the energy loss sources and the detailed classification of equipment attributes in the station. [Method] From the perspective of an energy storage power station, this paper discussed the main factors to be considered in the energy consumption calculation of prefabricated cabin type lithium iron phosphate battery energy storage power station, and then divided the energy consumption of the energy storage power station into two parts, namely, the energy consumption of the energy storage system and the energy consumption of the auxiliary equipment operation. Besides, it also provided the calculation method for the energy consumption of each part and the selection method of efficiency value respectively. [Result] Through a practical calculation example, the whole-day energy consumption of a 2 MW/2 MWh energy storage battery prefabrication cabin in a certain operation mode is analyzed and compared with the field test results. The difference between the field test results and the theoretical analysis results is analyzed from the perspective of the heat produced by the energy storage battery and the heat transmitted by the air conditioner, and suggestions are put forward for the energy consumption statistics of the energy storage power station. [Conclusion] The energy consumption calculation method proposed in the study comprehensively discusses the main factors affecting the energy consumption index of the prefabricated cabin type lithium iron phosphate battery energy storage power station and gives the energy consumption calculation method for the main equipment according to the detailed classification of equipment attributes, which has a good engineering reference value.

[Introduction] The research and development of offshore floating photovoltaic complies with the needs of national energy strategic development, caters to the background of industry development led by science and technology, and helps the development of emerging economic industrial chain. This paper aims to deeply explore the main components and core technologies of offshore floating photovoltaic system, and provide a theoretical basis for the development of offshore floating photovoltaic in China. [Method] Based on the existing research on offshore floating photovoltaic at home and abroad, this paper refined the relevant construction technology of flexible photovoltaic, verified the commercial feasibility of offshore floating photovoltaic development, introduced the configuration and composition of large-scale offshore floating photovoltaic (LOFPV) system, expounded the hydrodynamic design theory and method basis of flexible membrane structure and mooring system, and showed the typical engineering practice of offshore floating photovoltaic. [Result] Offshore flexible membrane-based floating photovoltaic has many advantages, such as lightweight, miniaturization, high power exchange efficiency and flexible configuration. In addition, the membrane structure is foldable, convenient for transportation, and convenient for installation, and the overall structure has no complex connector, so the system has high reliability and is convenient for operation and maintenance. Relevant achievements of this paper will provide great reference value for the development of China's offshore floating photovoltaic technology. [Conclusion] The functionality and reliability of flexible membrane-based floating photovoltaic construction technology are explained, and this flexible membrane structure will definitely be an important application type of offshore floating photovoltaic in the future.

[Introduction] The strategic goal of "carbon peaking and carbon neutrality" has increased the demand for new energy power grid integration, so it is necessary to improve the flexible operation capacity of coal-fired generating units. [Method] This paper introduced the flexible transformation technology and common evaluation indicators of existing coal-fired units in detail. Flexibility transformation mainly included condensate throttling technology, coupled biomass co-combustion transformation technology of coal-fired units, flexibility technology of pulverizing system of coal-fired units, etc.; Common evaluation indicators for the flexibility of coal-fired generating units included: the power consumption rate of the generator set plant, the thermal efficiency of the boiler, the standard coal consumption rate of the generator set, etc. On this basis, this paper summarized and analyzed the flexibility transformation technology and evaluation indexes. [Result] Finally, the paper puts forward seven kinds of the technology development direction and relevant suggestions of coal-fired generating units. [Conclusion] The structural improvement of original generating units, the introduction of multi-form new energies and the coordinated regulation design of multi-heat storage will be the main direction of subsequent development. It is expected that paper can provide reference for subsequent coal-fired generating units to adapt to "dual carbon" energy planning.

The fourth generation synchrotron radiation light source puts forward higher requirement for the alignment accuracy of the equipment, including the positioning accuracy of the equipment in a large space and the alignment monitoring accuracy of the equipment position after the machine is running. According to the alignment requirement of Hefei Advanced Light Source, the horizontal positioning accuracy within 30 m straight-line section is required to be better than 50 μm. In order to ensure the normal operation of the accelerator, new technical means must be used to monitor the lateral displacement of key components in the accelerator with high precision. The on-line alignment monitoring measurement is an important means to monitor the stability of particle accelerator system. Laser alignment with the characteristics of fast response and high accuracy, is an important data reference source for on-line alignment or adjustment. In this paper, a high-precision long-distance micro displacement monitoring system based on the similarity measure of laser spot was proposed. The lateral position offset of the measured system was monitored by measuring the displacement of laser imaging spot. Firstly, the structure and working principle of the laser light path control and detector assembly of the system were introduced, and the key errors of the system were analyzed, and then the similarity measurement algorithm of the light spot was used to monitor the lateral displacement. The similarity measurement algorithm used in this paper is an image processing algorithm that analyzes the similarity between the template and the search image. The similarity measurement algorithm takes advantage of the stability characteristics of the laser spot and uses interpolation function to calculate the minimum difference between the template and the search image, so as to obtain the position change value of the spot in the search image. Under the influence of random noise, the accuracy of the algorithm is better than ±0.17 pixels (pix). Finally, a 40 m long prototype system was built. Using the similarity measurement algorithm, the relative position deviation of the measured targets at different monitoring positions was obtained at different times. After testing, the horizontal monitoring accuracy of the system is better than 8 μm and the monitoring accuracy of the prototype is not related to the distance of the measured target. The successful development of the prototype system can provide basic data for the development of further micro displacement detection system, and can be applied to the on-line displacement monitoring of accelerator equipment such as fourth generation synchrotron radiation light sources, free electron lasers, linear colliders, etc.

An accurate two-phase flow model is an important basis for nuclear reactor safety analysis. The classical two-fluid six-equation model used in many current thermal-hydraulic programs has an ill-posed problem, if a small disturbance is introduced, the system parameters will oscillate greatly, resulting in unstable calculation results. In the existing researches at home and abroad, the most commonly used solutions to this problem are adding the virtual mass force or additional interphase interface pressure. However, the model can only be improved to a certain extent, and the ill-posedness of the model cannot be completely eliminated. The effective solution is to restore the two-phase pressure nonequilibrium and increase the volume transport differential equation to form a twopressure seven-equation model. In addition, a relaxation term is introduced to describe the multi-dimensional motion phenomenon of the interphase interface, and the concept of a relaxationtype twopressure model is proposed. This paper expounded the establishment method of the relaxation two-pressure model in LWR systems, discussed the processing methods and significance of the interphase interface pressurevelocity relaxation process, summarized the calculation method of the twophase mobile interphase interface, and introduced the numerical solution method of the model. Through eigenvalue analysis, the relaxed twopressure twofluid model studied in the paper is absolutely well-posed, which can solve the ill-posed problem of the original sixequation model. The relaxation term in the model can accurately describe the multi-dimensional motion on the interphase interface. There are two ways to obtain the relaxation coefficient, one is based on the relaxation time scale and the other is based on the acoustic impedance. The expression based on the acoustic impedance is only valid under high-speed flow conditions. For lowspeed flow, the first expression related to the traditional viscous resistance is more appropriate. The Riemann problem solution can be used to approximate the pressure and velocity on the interphase interface to solve the two-phase discontinuity at the interface. In the numerical solution of the model, a large number of existing researches use the step-by-step method to solve the problem, and the solution generates more intermediate variables and occupies a large space. There are also studies which solve the model as a whole, which preprocess the mass conservation equation and momentum conservation equation into the form of sumdifference differential equations to overcome the numerical instability problem caused by the disappearance of vapor/liquid phase. This paper summarized the existing research results and analyzed the future development direction of the relaxation twopressure twophase flow model, in order to provide theoretical reference for subsequent research.

Venturi-type bubble generator as well as its performance has been received wide attentions by engineers and researchers in recent decades. In this paper, experimental research was carried out to study flow regime and pressure drop of the gas-liquid (air-water) twophase through a Venturi bubble generator. The bubble generator was designed with a rectangular cross section, and the gas was injected into the high speed water flow from the throat section of the Venturi. Interface distribution and dynamic processes of bubbles were observed with a high speed camera, and the static pressures of inlet, throat and outlet of the bubble generator were measured by pressure sensors. Such three basic regimes as bubbly, slug and column are preliminarily identified in the bubble generator by visual experimental observations. A significant increase of the pressure drop of the bubble generator is found in the experiment when the flow regime transformed from slug into column. In order to identify the flow regime of the bubble generator, time frequency of pressure signal was analyzed, and it is found that the outlet section of the bubble generator is confirmed as the most favorable position for pressure signal on-line monitoring. A relative kurtosis of probability density function and a coefficient of variation of power spectrum density strongly associated with flow regime transition were extracted from the pressure signals, and they were applied to identify slug-column and bubbly-slug transition, respectively. Since the traditional pressure drop models can’t precisely predict the whole pressure drop of the Venturi bubble generator, a new pressure drop prediction method is proposed. The effects of partial liquid single-phase flow and flow regime transition on the pressure drop prediction are considered in the new correlation by introduced two modified parameters, ′ and θ′, respectively. Both of the two modified parameters were fitted from the current experimental results. Prediction results of the new correlation agree well with those of the experiments with a relative root mean square deviation of 10.74%. The new correlation is applied to the two-phase flow under conditions of normal temperature and 1-1 times of atmospheric pressure, while the liquid flow Reynolds number ranges from 1.7×104 to 7.0×104 and the low mass quality ranges from 0 to 5.1×10-5. The new method proposed in this paper for predicting pressure drop of the device regarding gas-liquid two-phase flow can provide theoretical bases and references for the online monitoring of the similar device.

The structural materials in the reactor and the corrosion products in the loop will be activated into radionuclides after being irradiated by strong neutrons. These nuclides and their decay products are the main sources of radiation hazards for workers. Therefore, the efficient and accurate calculation of the inventory of these radionuclides is of great significance for the design of reactor shielding protection, radioactive source items and waste management. In this paper, the neutron activation calculation method based on the mini-max polynomial approximation (MMPA) method was studied. Compared with the traditional neutron activation calculation methods such as the transmutation trajectory analysis method and exponential Euler method, MMPA method has the advantages of good numerical stability, high efficiency and no need to deal with short-lived nuclides alone. Furthermore, two solution strategies based on the MMPA method were studied for activation calculation, including the direct inversion solution strategy and the iterative solution strategy. The first solution strategy was proposed by Yosuke Kawamoto. This solution strategy completed the solution of the nuclide density by directly inverting the coefficient matrix and then calculating the multiplication and addition of multiple matrices. This solution strategy was computationally inefficient because it involved matrix inversion operations and a large number of matrix and vector multiplication operations. Therefore, a second solution strategy was proposed to improve the computational efficiency of the MMPA method. This solution strategy firstly transformed the solution expression of the MMPA method into an iterative expression after appropriate transformation, then obtained the substitution matrix for each iteration based on LU decomposition, and finally completed the solution of the nucleon density by adding multiple matrices. Compared with the first solution strategy, the solution strategy avoids the direct inversion of the matrix, and effectively reduces the number of multiplications of the matrix, so it has higher solution efficiency. Based on the self-developed nuclide inventory calculation code AMAC, the two solution strategies of MMPA method were completed. The correctness of MMPA method applied to neutron activation calculation under multiple conditions was preliminarily verified by typical material activation examples and self-constructed large-scale coefficient matrix examples under irradiation conditions, decay conditions and pulse conditions. The test results show that the calculation results of MMPA method are in good agreement with the calculation results of each reference solution, and the calculation accuracy is equivalent to that of 16 order Chebyshev rational approximation method (CRAM). In terms of computational efficiency, the solution efficiency of the iterative calculation strategy based on MMPA proposed in this paper is significantly higher than that based on direct inversion. The computational efficiency of this calculation strategy is equivalent to that of 16 order CRAM. The MMPA method is feasible in neutron activation calculation, and has good calculation accuracy and high calculation efficiency.

Rod-pinch diode is widely used in flash X-ray machines of various voltage levels. Its structure is very simple and the radiation dose is high with a small focal spot. The most important thing in the physics of rodpinch diode is to study the emission state of electrons and ions under different voltage-loading waveforms. At present, the theory of electron explosion emission has been mature, but there is a lack of specific research on the property of plasma emission except that anode plasma is indispensable. Therefore, the study of anode plasma emission of the rod-pinch diode is helpful to deeply understand the influencing factor of plasma on radiation dose. Improving the radiation imaging performance of rod-pinch diode by adjusting plasma emission, like pre-filled rod-pinch diode, PIC and Monte Carlo simulations were used in this paper. PIC simulation was used to obtain the peak current of the rod-pinch diode and the phase space file storing the electron bombarding the anode. The phase space file was used as the input source file of Monte Carlo to obtain the simulated radiation dose of the rod-pinch diode. Three X-ray devices of 450 kV, 1 MV and 4 MV were used to obtain the diode current and radiation dose at 1 m of the rod-pinch diode at the voltage level of 0.45-4 MV. By comparing the simulation result with the experimental result, the correct plasma emission function of the anode rod was obtained. According to the above methods, it is confirmed that the plasma emission function is closely related to the energy and power of electron bombarding the anode rod, and the ion emission function of anode rod with different diameters at the voltage level of 0.45-4 MV is obtained. At the same time, it is found that the position of the electron bombardment anode rod corresponds to the position of plasma emission. It shows that the heat transfer of electron deposition energy on the anode rod cannot be considered in the time range of X-ray emission. After the anode ion emission function obtained in this paper was added to the numerical calculation model, the relative error between the simulated peak current and radiation dose and the real experimental value is within 20%, which can accurately predict the diode current and radiation dose in the flash X-ray experiment. Using this model, the relationship between plasma density and electron bombarding anode rod was studied. Electrons bombarding the side of the anode rod with near grazing incidence and the end face of the anode rod can obtain a higher X-ray radiation dose. Combined with 3D modeling technology, the simulation method can fully evaluate the penetration ability of X-ray in a specific object, to scientifically select the input voltage level in the formal experiment. At the same time, combined with material science and related technology, the model can also be used for the design of a new X-ray diode.

Due to the small thermal neutron absorption cross section of 11B isotope, high abundance 11BF3 is regarded as an important ion implanted gas and P-type doping source, and is mainly used in semiconductor material manufacturing process to significantly improve the anti-radiation interference ability of semiconductor devices. In order to achieve the optimal design of the high-abundance 11BF3 isotope separation process, the mechanism of chemical exchange separation of 11BF3 isotopes was analyzed firstly, and the results show that the difference of intermolecular forces is responsible for the isotope separation. Then, the relative molecular weight and saturated vapor pressure data of isotope molecules were supplemented by self-defined components, and the parameters of the extended Antoine equation were regression extended in the Aspen Plus commercial chemical process simulation software. The process model of 11BF3 isotope separation based on Aspen Plus was established. RStoic reactor module was used for complexation and cracking reaction calculation, and Radfrac strict rectification module was used for exchange process calculation. Since the separation coefficient calculated by using NRTL-RK thermodynamic method was the closest to the experimental value, NRTL-RK thermodynamic method was selected for calculation in the exchange tower. In the complex tower and the cracking tower, the gas-liquid exchange process was not considered, so NRTL thermodynamic method was used. Next, based on the two sets of experimental data, the Murfree plate efficiency was used to correct the model in Aspen Plus, and the relative errors between the two sets of simulated and experimental values are -2.69% and 0.91%, respectively. It shows that the modified model can describe the process of 11BF3 isotope separation well. Finally, according to the established mathematical model, the effects of theoretical plate number, reflux ratio and column top pressure on the 11BF3 isotopic abundance at the top of the exchange column were analyzed. The results show that the decrease of the column top pressure, the increase of the reflux ratio and the increase of the theoretical plate number are all beneficial to the 11BF3 isotopic abundance. The maximum abundance of the exchange tower reaches 99.95% when the column top pressure is atmospheric pressure, the theoretical plate number is 720 and the reflux ratio is 300. The results of this paper can provide a theoretical basis for the subsequent optimization design. Subsequently, the 11BF3 isotope separation process model established in this paper can be further used to conduct multi-objective comprehensive analysis of investment cost, operating cost and abundance.

The accurate calculation of pressurized water reactor burned fuel neutron source intensity plays a significant role in the subcritical reactivity measurement. The calculation methods of both spontaneous fission source and (α, n) neutron source were researched in this paper. There were multiple sources of alpha particle in reactor core, including 238Pu, 239Pu, 240Pu, 241Am, 242Cm, 244Cm, etc. Among these sources, the dominant source was coming from 242Cm decay. 242Cm approximation method as well as ratio fitting method were proposed for obtaining (α, n) neutron source intensity. In 242Cm approximation method, all alpha particle sources were neglected with the exception of 242Cm. The ORIGEN code was used to analyze the ratio of (α, n) to the spontaneous fission neutron of 242Cm for different enrichment assemblies at different shutdown time. It is found that the ratio of (α, n) to the spontaneous fission neutron of 242Cm is fixed around 0.191. Therefore, the neutron number density of spontaneous fission neutron is multiplied by the factor of 0-191 to obtain (α, n) neutron source intensity due to 242Cm decay. On account of neglecting all (α, n) neutron source intensity with the exception of 242Cm, it is foreseeable that 242Cm approximation method would underestimate (α, n) neutron source intensity. In ratio fitting method, the ratio of (α, n) to the total neutron source intensity was analyzed. It is found that the ratio of (α, n) to the total neutron source intensity is linearly related to the burunp when the burnup is greater than 20 000 MW·d/tU. Therefore, two fitting methods were proposed to obtain the ratio of (α, n) to the total neutron source intensity. The polynomial fitting method was used with burnup less than 20 000 MW·d/tU, on the other hand, the liner fitting method was adopted with burnup greater than 20 000 MW·d/tU. Based on the in-house core design code package, the burned fuel neutron source calculation module was developed. In order to account for reactor core space effect and burnup history effect, the micro-depletion correction method in core design code package was used to obtain accurate number densities of actinide nuclides. The developed module was verified by calculating fuel assembly examples. Comparing with the reference code, the maximum errors of total source intensity is about 5% provided by both 242Cm approximation method and ratio fitting method. With the developed burned fuel neutron source intensity calculation module, both radial and axial distributions of burned fuel neutron source intensity in the reactor core are obtained. These distributions are of significant importance to ex-core detector signal measurements. The work in this paper is an important technology support for subcritical rod worth measurement development.

The nuclear power plant is a complex technical facility with potential radioactive hazards. Therefore, timely identification and treatment of accidents are necessary to avoid serious consequences. In order to quickly obtain information on nuclear power plant accidents and provide a new auxiliary means for the analysis of operator safety, it is necessary to study the accident diagnosis method and establish an accurate and reliable accident diagnosis model suitable for nuclear power plants. However, it is tough to establish a complete and accurate model of the nuclear power plant based on the model-based diagnosis method. The method based on expert knowledge needs a lot of expert experience knowledge which is difficult to obtain. Based on continuous data accumulated, the data-driven method can adaptively map the nonlinear relationship between symptoms and accidents, which is more suitable for fault diagnosis of the nuclear power plants. The data obtained by online monitoring for nuclear power plants are time series data with high data dimensions. However, there are few accident data, which makes it challenging to meet the training requirements of standard deep neural networks such as convolution neural network and time convolution network. Therefore, according to the data characteristics and high accuracy requirements of the nuclear power plant, a nuclear power plant accident diagnosis method based on time convolution capsule network was proposed in this paper. Firstly, the high-dimensional data obtained from the real-time monitoring of the nuclear power plant were input into the time convolution kernel to extract the depth of time-series features information of the data and reduce the difficulty of calculating. Then, the depth vector features of the data were mined through the capsule network to maximize the use of the data features of the operational information, which could also get a good convergence effect in the case of fewer accident data. Finally, the accident simulation data of the nuclear power plant were obtained by Fuqing simulator to train and test the model. The simulation data of regular operations and nine other accidents were collected to test the accident diagnosis model built in this paper. When the training set only accounts for 20% of the data set, it can still quickly and stably converge and accurately diagnose the accident information, and the diagnosis accuracy is more than 99%. Finally, the method in this paper was compared with other conventional depth learning methods through experiments. The results show that the time convolution capsule network model has better convergence and diagnostic accuracy than traditional machine learning and in-depth learning methods when the accident data of the nuclear power simulation system are not enough. The research content of this paper can provide some theoretical basis and technical reference for the application of the fault diagnosis method in nuclear power plants.

ASME 2021 code provides constitutive equation for high temperature creep of 316H stainless steel. The paper aims to help engineers and researchers correctly evaluate the strain and creep damage of high-temperature equipment by using the equation. Firstly, the physical mechanism of the items was explained. Secondly, the relationship between crucial parameters with temperature and stress was analyzed. Thirdly, the applicable stress and time range of the 316H creep constitutive equation was briefly introduced. And fourthly, the prediction values of the constitutive equation was compared with the data value from the isochronous stress-strain curve in ASME code. Results show that the constitutive equation is described by three items, in which the first creep stage is described by the rapid initial transient and transient items, and the second creep stage is described by the steady-state creep item. The equation’s applicability of evaluating the strain and creep damage of high-temperature equipment is limited by the starting time of the third creep stage. Moreover the key parameters of the equations, such as εs, εr, decay too rapidly to be accurately predicted at high stress. This research finds that due to item n increases with increasing temperature, the minimum creep rate m and transient creep rate constant r decrease in 1 000-1 075 ℉. Meanwhile, based on contrasting the rapid transient creep rate constants s of the original paper and ASME code, item D of parameter s is incorrect in the latter. Based on comparing predicted strain obtained by equation and data from ASME code isochronous stress-strain curves, the paper finds that predicted values at 950, 1 050 and 1 150 ℉ will agree with isochronous stress-strain curves, but larger than the datum from curve at 1 000 ℉, resulting in a relatively conservative strain prediction. Based on above four research and results, the paper concludes that the high temperature creep constitutive equation of 316H stainless steel in the ASME code can be used to evaluate high-temperature equipment structural integrity at 950, 1 050 and 1 150 ℉, but the result of 1 000 ℉ is conservatism.

Heat-pipe-cooled reactors offer many advantages, such as modularity and no flow loops. In recent years, it has attracted the attention of many scholars. Solid cores involve complex thermal-mechanical coupling behavior over their operating lifetime. The deformation of solid core structure has significant influence on its heat transfer performance. This paper introduced the gap heat transfer model by Ross and Stoute, which is an important part of the heat transfer process in the core. The creep and swelling behavior of materials used in solid core under high temperature and irradiation environment was briefly described. In this paper, a simplified finite element model of solid core was developed based on the secondary development of ABAQUS by programming subroutines, which considered the effect of gap heat transfer, creep and swelling behavior in the core. Based on the Ross-Stoute gap heat transfer model, the subroutine GAPCON was developed to simulate the gap heat transfer behavior in the core. The subroutine CREEP was developed to simulate the complex mechanical behavior of core components under different temperatures and radiation environments. Typical characteristics of temperature and stress distribution in each component during the normal operation period of 5 years were obtained. The thermal-mechanic coupling behaviors of solid core and the interaction between components were analyzed. The high temperature area appears in the center of the fuel pellets, and the temperature drops along the radial direction of the fuel pellets. This distribution of temperature field results in the inner extrusion and the outer tension of fuel pellets. The annular tensile stress region appears obviously outside the fuel pellets. These temperature and stress distribution characteristics can partly explain the radial cracking behavior of cylindrical fuel pellets. Furthermore, the designed size of the solid core was optimized based on finite element and machine learning to obtain lower temperature and stress peaks. The parametric modeling technique of ABAQUS was used to generate 5 800 sets of data, and the sample database was established for the training and testing of deep neural network machine learning. A surrogate model of core design parameters, maximum temperature and Mises stress in the reactor was established. The surrogate model had good predictive accuracy. Based on the surrogate model, pareto front was obtained by NSGA-Ⅱ algorithm and the optimized design parameters were obtained. The results of core temperature and stress optimized by surrogate model were verified by finite element method. Compared with the initial design, the maximum temperature decreases by 8.44% and the maximum stress decreases by 34.43%. The performance of the core is improved.

ObjectivesThis paper aims to study the problems that the external electrical characteristics of a hydrogen fuel cell are soft, its dynamic characteristics are poor and its system stability is susceptible to the influence of propulsion load in marine hydrogen storage DC electric propulsion systems. MethodsFirst, an analysis is performed of the output external electrical characteristics of the hydrogen fuel cell and the propeller load conditions of the marine electric propulsion system, then a ship-engine-propeller model and a frequency-domain model of drive control system for a permanent magnet synchronous motor (PMSM) are set up. Next, a speed-loop bandwidth design method is proposed, considering the external electrical characteristics of hydrogen fuel cell and propeller load conditions. Finally, on basis of the parameters of a mother ship, an electric propulsion system for a hydrogen-battery DC electric propulsion ship in a hardware-in-loop experimental platform is established to verify the proposed method.ResultsThe experimental results show that the speed response of the motor has no overshoot under this method, and the speed-loop fluctuation is reduced by 5 r/min when the load torque disturbance occurs. ConclusionsThe speed-loop bandwidth design method proposed in this paper improves the comprehensive characteristics of the ship hydrogen storage DC electric propulsion system, and is easy to implement in engineering.

ObjectiveThis paper aims to evaluate the impact of flow-induced vibration on the receiver performance of low-frequency magnetic antenna in an underwater environment, investigating the electromagnetic-induced noise of antenna under different vibration conditions. MethodsFirst, a fluid excitation antenna vibration model is established using COMSOL software, then an antenna vibration-induced noise model is constructed to simulate electromagnetic-induced noise. Finally, outdoor experiments to measure the antenna vibration-induced noise are carried out. Results The results show that the stronger the antenna vibration is, the greater the electromagnetic-induced noise is. When the antenna vibration acceleration reaches 0.029 4 m/s², the electromagnetic-induced noise above the pT level will be caused, and the normal communication signal will be submerged. ConclusionThe results show that the proposed model in this paper can be used to evaluate the vibration-induced noise of low frequency magnetic antenna.

Bacterial quorum sensing (QS) is a process in which bacteria conduct chemical communication through the production, release, accumulation and induction of signaling molecules called autoinducers (AI). Aeromonas is a common spoilage bacterium in aquatic products, and also a conditional pathogenic bacterium in animals and humans. In recent years, studies have reported that the pathogenicity and spoilage behavior of Aeromonas may be related to QS, suggesting that it can be prevented and controlled by inhibiting the QS. Aeromonas has three QS systems including AI-1 system with N-acyl homoserine lactones (AHLs) as signaling molecules, AI-2 system with 4,5-dihydroxy 2,3-pentanedione (DPD) derivatives as signaling molecules and AI-3 system regulated by QseBC. This paper introduces these three QS systems and their regulation mechanisms in detail. Furthermore, this paper focuses on recent progress in research on plant-derived, microbe- and animal-derived and chemically synthesized QS inhibitors (QSI) of Aeromonas. The potential application of QSI to the prevention of aquatic product spoilage and aquatic diseases caused by Aeromonas is discussed in order to provide a reference for the application of Aeromonas QSI in aquatic product safety.

The hardware imperfection can generate a unique fingerprint of the trasmitter, and it is attached to the radio signal. The unique attribute of transmitter can be used for Radio Frequency Fingerprinting (RFF). Due to the unknown channel conditional and the lack of prior information such as modulation scheme, the traditional method of RFF faces huge challenges to non-cooperative conditions. On the contrary, RFF methods based on Deep Learning (DL), especially those that can directly process raw I/Q, show great potential. However, the research results of this direction are scattered, which seriously hinders researchers from grasping the key issues. This paper first classifies and compares the RFF methods based on DL according to the utilization of prior knowledge, and focuses on the RFF methods based on raw I/Q and DL. Then, this paper focuses on the classification and discussion of the deep neural network model of RFF using raw I/Q, and summarizes the open source data sets, data representation methods and data augmentation methods related to RFF. Finally, this paper discusses the difficulties and research directions of the RFF based on DL, hoping to help the research and application of the RFF.

Based on a large number of field investigations and the analysis of the "analogous hyperbolic" overall movement model proposed by the author, this paper further extends it to three-dimensional space, and proposes a full-space "analogous hyperboloid"three-dimensional movement model of the mining strata.There are two types of hyperboloids, "quasi-single-leaf"and "quasi-double-leaf", which can approximately describe the three-dimensional movement and surface subsidence characteristics of full-space mining strata under different lithological conditions.The "analogous single leaf hyperboloid" model is a horizontal moving boundary model of the spatial rock layer, which is implicit in the thick loose layer overlying rock; the "analogous double leaf hyperboloid" model is the vertical movement of the spatial surface subsidence and the overlying fissure arch and caving arch.The boundary models are approximately symmetrical with the "origin" in the main key layer, and are embodied in external forms such as surface subsidence under mining disturbance and arch caving of the surrounding rock in the stope. Through theoretical analysis, similar model test and 3DEC numerical simulation, this paper deduces and proves in detail the "analogous hyperboloid" model of spatially mined rock strata movement and surface subsidence under the condition of near-horizontal coal seam mining in thick loose layers.At the same time, this study analyzed the composition conditions, influencing factors and overall migration law of the co-asymptotic conical surface "analogous hyperboloid" model.Results show that under the condition of near-horizontal coal seam mining with thin bedrock and thick loose layer, the "quasi-hyperboloid" theoretical model is in good alignment with the 3DEC simulation results, indicating that the overlying rock migration and surface subsidence in space mining are "analogous hyperboloid" feature.

If the shearer is cutting coal using the "memory cutting" technique, a manual demonstration is required.The memory cutting technology has higher requirements on the reserving conditions of coal seams.When the coal seam fluctuates greatly, frequent manual demonstrations are required.The "memory cutting" technology only optimizes the cutting path of the coal seam roof for the next cutting.Along the advancing direction of the shearer, it is impossible to accurately plan and control the pitching angle of the shearer according to the reserving conditions of the coal seam.Based on the concept of shearer self-adaptive intelligent cutting, this paper designs the operation mode of the shearer intelligent cutting system in the fully mechanized working face.In this model, the high-precision three-dimensional geological model of the working face is first constructed by using the highly accurate geophysical data of the coal seam, and then the future cutting path of the shearer is planned by using the model.At the same time, the high-precision three-dimensional geological model is dynamically corrected by using the latest geological data of the working face during the mining process.In this paper, the high-precision three-dimensional dynamic geological model is coupled with the shearer mining planning algorithm.According to the model, a shearer mining control baseline planning algorithm that can adapt to the changes of the coal seam is proposed, which realizes the pitching control of the shearer in the advancing direction and the cutting control in the pulling direction, as well as the efficient cooperation between the update of the geological model, the planning of the mining baseline and the adjustment of the shearer drum.The calculation service interface of the drum adjustment parameters in the intelligent cutting system and the communication protocol between the intelligent cutting system is designed.Addtionally, the shearer control system is considered.This realizes the precise control of the shearer drum based on the planning cutting path.The intelligent cutting system of fully mechanized working face is applied to guide the production of shearers.The practice shows that the shearer intelligent cutting system is suitable for coal seams with various degrees of floor inclination.The cutting line of the shearer can better fit the roof and floor lines of the coal seam, which can save resources and improve production efficiency.

In order to find out the key causes of changes in spontaneous combustion characteristics of igneous intrusive coal seams, this paper took the Daxing Coal Mine in Tiefa Coalfield as example for analysis, which was widely invaded by igneous and had serious coal spontaneous combustion disasters.Metamorphic coal and unaffected primary coal were collected from the study area.Specifically, this paper studied the patterns of heat production and temperature rise, gas production rules, and microscopic structure parameters of coal samples by synchronous thermal analyzer and coal spontaneous combustion characteristic measuring device.The experimental results show that the igneous intrusion caused the mutation in the spontaneous combustion characteristics of the coal.Compared with the primary coal, there was significantly higher oxidation heat release of the metamorphic coal at the low temperature stage.Also, the crossing point temperature of metamorphic coal was reduced by 13.2 ℃, and it entered the stage of oxidation and weight gain earlier than the primary coal.When the environment temperature exceeded 90 ℃, the oxidation heat generation and reaction rate of metamorphic coal increased rapidly, which showed higher oxygen consumption rate and faster generation rate of oxidative gas products such as CO and CO2.This demonstrated higher oxidation activity of metamorphic coal than that of primary coal.The analytic results of physicochemical microstructure showed that the high temperature and pressure of igneous intrusion changed the pore structure of coal, which reduced the pore volume and specific surface area of micropores/mesopores in metamorphic coal, and the pore volume of macropores was three times higher than that of primary coal.The average pore size and porosity increased significantly, which was conducive to the transport, migration and adsorption reaction of oxygen molecules in the coal structure.At the same time, igneous intrusion reduced the oxygen-containing functional groups of metamorphic coal, and the content of aliphatic hydrocarbons with higher activity increased from 27.98 % to 29.07 %, which enhanced the oxidative activity of metamorphic coal.Moreover, igneous intrusion caused problems such as increased air leakage, long oxidation time of left coal, and wide oxidation zone during the mining, eventually leading to severe coal spontaneous combustion disasters.

With the increase of coal mining depth, the stress environment of the surrounding rock of the roadway deteriorates, therefore it becomes a prominent problem for the large deformation of the surrounding rock and the breaking of the bolt and cable, which seriously affects the safety of deep mine production.To solve such problems, this paper focuses on the advantages and disadvantages of bolt and cable support.Based on the interaction mechanism between Anchor Cable with C-shaped tube(ACC)and surrounding rock, this paper proposed a new ACC support technology.ACC optimizes the stress state by improving the structure of the free section of the anchor cable.It can not only enhance the anchor cable's axial bearing capacity but also prevent the free section of the anchor cable from breaking due to lateral action.It can avoid the problem of instability of surrounding rock.Through the shear test, it is found that the maximum shear load of the ACC is more than 1.27 times that of the ordinary anchor cable, and the average maximum shear displacement is 1.16 times that of the ordinary anchor cable, which indicates that the ACC has good shear resistance and shear direction extension properties.Based on the engineering case of the roadway of Jiulong Mine, this study analyzes the deformation and failure characteristics of the roadway under the original support scheme through on-site monitoring and borehole detection, and has successfully applied the ACC in the deep large-deformation roadway.The field monitoring results show that the new technology of ACC can effectively control the large deformation of surrounding rock.The results of this study can provide reference for similar deep mine support.

With the progress of urbanization and the refining of research content, it is more urgent to study the integration of urban and rural public services. In this paper, with the papers on the main journals containing urban and rural public service integration research results as research object, bibliometric method and the visualization method of CiteSpace and CNKI were adopted to carry out fundamental reviewing from the number of papers, authors and institutions, and knowledge background, and then to conduct comprehensive analysis on hot research topics, theme connotation, and the law of development, and finally to get the objective results from the view of result evaluation and research extension, so as to provide the necessary basis and enlightenment for further study of urban and rural public service integration in China in the future.

Aiming at the shortcomings of isotope radon detection method, which has large workload, long period, and is easily restricted by climate and environmental factors this paper proposes the use of radon generated during the process of migration to the surface to accurately reflects the solid-state length of the cumulative value of parent radon over a period of time. Long-lived radon daughter 210Po fire detection method based on radiochemical analysis method to measure 210Po activity concentration to detect hidden mine fire areas. In order to explore the effect and accuracy of the radon progeny 210Po fire detection method in on-site detection, this paper carried out on-site experimental research in Liuwan Coal Mine where the fire source location is known. The radon gas concentration at the measuring point and the activity concentration of its solid long-lived daughter 210Po are measured. By comparing the correlation between radon gas concentration and 210Po activity concentration detection results and its influencing factors, the technology of using radon daughter 210Po to detect the location of coal spontaneous combustion in goaf is demonstrated. The results show that the radon concentration in the near-surface soil layer in the fire area has a strong correlation with the 210Po activity concentration in the overall distribution, but the 210Po activity concentration is less disturbed by external factors, and its distribution can more accurately reflect the underground coal spontaneous combustion fire area. Compared with the isotope radon detection method, the radon progeny 210Po fire detection method has higher detection accuracy, wider application range and higher application value.

The integrated development of culture and tourism is one of the important ways for China to promote rural revitalization in the new era. Guangdong-Hong Kong-Macao Greater Bay Area uses the unique lychee cultural resources of the Lingnan region for tourism development, and has formed many local experiences and typical models on the road of integrated development of culture and tourism. This paper summarized the development connotation of litchi cultural resources in Guangdong-Hong Kong-Macao Greater Bay Area. Based on the existing studies on the integration of lychee cultural tourism, from the perspective of industrial economy, the experience of the integrated development of lychee cultural tourism in the Greater Bay Area is divided into four typical models: the integrated development mode of popular science research, the integrated development mode of cultural festival, the integrated development mode of picking experience, and the integrated development mode of industry and tourism joint operation. Through in-depth analysis of the main characteristics of different modes and typical case practice, the specific path and industry dynamics of the integrated development of lychee cultural tourism in the Greater Bay Area were clarified. Finally, from the perspective of problems, it is proposed that the Greater Bay Area can carry out mechanism innovation in the following aspects, such as government role, platform construction and public participation, so as to promote the integration of lychee culture and tourism to achieve a unified development direction of social benefits, cultural benefits and economic benefits. For the first time, this paper makes a comprehensive interpretation of lychee cultural tour, which relies on local fruit cultural resources to design rural revitalization road. The research results can provide some enlightenment for other areas to implement rural revitalization integrated development of cultural tourism.