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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.

PURPOSE This study was conducted for the purpose of exploring the direction and quality of Pilates research in the future by comparing and analyzing research trends in the field of Pilates natural science at home and abroad. METHODS In order to analyze domestic and foreign Pilates research trends, we analyzed academic papers of the last 10 years (2013-2022) in the natural science field, and domestic papers were used as the keyword ‘Pilates’ using DP Pia, Kiss, and Riss, which are academic information services. A total of 105 papers were used by searching. For overseas studies, Pub med and Scholar were used, and only SCI and SCIE papers were collected and 129 papers were searched. RESULTS First, according to the comparative analysis of research trends by domestic and foreign fields, physiology (61%), kinematics (24.8%), and rehabilitation (14.2%) were found in the order of domestic, whereas in foreign countries, kinematics (34.9%) and physiology (33.3%) and rehabilitation (31.8%), a study with a relatively even distribution was conducted. Second, in the comparative analysis by study subject, domestic literature was the highest with 68.7% of studies targeting women, and was conducted separately by various age groups. Foreign fields, 40.9% of studies conducted by gender were found, and there were many studies that considered the characteristics of musculoskeletal disorders and metabolic diseases rather than gender. Third, looking at the comparison by research variable, studies have been conducted on various topics in physiology and kinetic dynamics. However, while domestic studies have focused on changes in body composition, foreign studies are actively conducting research on muscle function, musculoskeletal disorders, and rehabilitation. CONCLUSIONS In summary, it is judged that active research in the field of kinematics and rehabilitation should be conducted for more diverse subjects in the field of Pilates.

With the improvement of living conditions, people’s eating habits gradually trend to “healthy” development. However, it is difficult to strike a balance between “healthy” and “delicious”. Seasoning is a crucial step during cooking. Saltiness is one of the five basic tastes, and it is produced mainly by adding salt in daily life. Salt plays an important role in human life, but excessive sodium intake can lead to many cardiovascular diseases. Today many health authorities around the world advocate a low-sodium diet. In this context, reducing the amount of salt in foods without affecting their flavor or quality has become a popular research topic. This paper reviews the mechanism of salty taste perception and the current status of salt reduction in foods, with special focuse on salty peptides. The sources, preparation and identification methods, synergistic effect and application prospects of salty peptides are outlined in this paper, so as to provide a basis for the development and application of salty peptides, which will help in advancing the salt reduction campaign.

In order to summarize the current status and evolution of surimi research in China and globally, 944 and 1 082 research paper published in the period of 2009 to 2021 were retrieved using the keywords: yumi (in Chinee) and surimi from the China national knowledge infrastructure (CNKI) and Web of Science (WOS) databases and were test mined for the number of research papers, authors, countries, institutions and journals using CiteSpace and the online bibliometric analysis platform. Moreover, data visual analysis was carried out by plotting keyword clustering, time line and burstness maps. It was found that there has been increasing interest in surimi research. The number of surimi research papers indexed in CNKI and WOS has shown an increasing trend in the period from 2009 to 2021, and most papers were published in the top journals in the food field. China has published 441 research papers in English, ranking first in the world, accounting for 37.99% of the world’s total, followed by Thailand, the United States and Japan. The close cooperation between authors and research institutions in different regions and countries has formed an international academic community. The research content has shifted from the macroscopic field to the microscopic field, and the research hotspots have changed from processing technology and surimi quality to preservation and antifreezers. At present, “protein” “myosin” and “secondary structure” have become new keywords and the research content has reached the molecular level. The time zone analysis showed that the keywords “sensory evaluation” and “quality” span the entire research period and have become the cornerstones of surimi research. In conclusion, surimi research is still in an active stage and will have a bright future.

Lipid is an important component except starch and protein in rice, which not only has unique nutritional value but also has a great impact on the functional properties of starch. In this paper, the species, structure, distribution, and content of lipids in rice were summarized, and the mechanism, structure characteristics and influencing factors of starch-lipid interaction were discussed. The interaction effects on the properties of starch, including swelling, gelatinization, rheology, retrogradation and digestive ability were reviewed. This paper provided useful information on understanding the interaction between starch and endogenous lipids in rice as well as its influence on the starch properties, which could promote the improvement of rice quality and the development of functional rice.

The construction of small modular reactor design is mostly for commercial power generation, and there are certain limitations in maneuverability and flexibility. In order to meet the demand of energy supply for special tasks, the vehicle-mounted very small modular reactor with more maneuverability arises at the right moment. In practical operation, vehicle-mounted reactor system will have multi-degree-of-freedom space movement, and the influence of vehicle movement on the reactor system is not clear at present. In this paper, the complex motion forms of the vehicle-mounted nuclear energy system running on the road were simplified into three types of operation forms. Based on the fluid force analysis in the non-inertial system, the additional force of vehicle-mounted motion conditions was derived from the momentum conservation equation, and a mathematical and physical model of vehicle-mounted motion conditions was established. The influence of additional force under motion condition on liquid lead-bismuth eutectic was analyzed reasonably, and corresponding additional force model was added into LETHAC program of transient thermal-hydraulic analysis program of lead-bismuth fast reactor to analyze thermal-hydraulic safety characteristics of LESMOR system under motion condition. The results show that the natural circulation flow of LESMOR system decreases significantly and the core cladding temperature and fuel temperature increase significantly under ramp driving, vertical vibration, pitching vibration and vertical coupled pitching vibration. Slope has little influence on the natural circulation of the system, and the change amplitude of system flow rate and temperature is small. The vertical vibration and pitching vibration will decrease the time domain average flow rate of the system and increase the time domain average temperature of the core outlet coolant. Due to the arrangement of the system, the pitching vibration has more influence on the heat exchanger than on the core. When the pitching vibration and vertical vibration are coupled, the average flow rate of the system in time domain decreases, and the vertical vibration plays a dominant role in the core flow rate. Under the limit condition, the transient drop of natural circulation flow of the system is not more than 30%, and the transient temperature of cladding and fuel is up to 411.3 ℃ and 442.4 ℃, and the rise is not more than 4 ℃, which is far below the safety limit of transient operation. The LESMOR system maintains stable and safe operation in both normal and possible driving limits. This paper provides a method to analyze thermal safety characteristics of reactor system under vehicle-mounted motion, which has certain reference significance.

[Introduction] With the development of Marine economy, more and more projects of offshore wind power transmission, offshore oil and gas platform power supply and island network power supply involve laying submarine cables. At present, the main laying protection method is direct burial laying, but the buried depth design without considering the economy is obviously unreasonable. In order to effectively protect the submarine cable and reasonably control the investment, it is necessary to determine the reasonable burial depth of the submarine cable in the project development stage. Therefore, in the absence of sufficient design input data, this paper proposes a simplified calculation method for the depth of anchor penetration, which provides a basis for determining the laying protection scheme in the early stage of the project. [Method] In this paper, the anchor penetration process was divided into three stages to establish mathematical models, and a series of boundary conditions were assumed for the anchor penetration process. On this basis, based on the energy method, we analyzed and deduced the mechanical model of the anchor movement process at each stage, and proposed a simplified calculation method of the anchor penetration depth considering the shear damage of the seabed substrate. By conducting a comparative analysis of the calculated values of the method and measured values under different situations, we explored the applicability and scope of the calculation method. [Result] The comparison between the calculated value of this simplified method and the measured result shows that this calculation method is suitable for calculating the depth of anchor penetration in the case of clay with shear strength greater than 20 kPa, and the calculation error of this method is within the acceptable range. [Conclusion] From the comparative analysis of the calculation results in this paper, it can be seen that the simplified calculation method has guiding significance for the application in engineering practice, but the method still needs to accumulate different measured data in practice for verification and fitting correction, and combine the empirical method and probabilistic method for further analyses, to provide design basis for submarine cable laying protection.

Fast-spectrum micro-reactor has many technical advantages, such as high energy density, good mobility, fast deployment speed, long life and so on. Because of the characteristic of compact structure and high role of leakages in the neutron balance in fast-spectrum micro-reactor core, geometric deformation caused by temperature change and mechanical effect under external force is the main source of reactivity feedback. So it is very important to carry out transient analysis based on neutronics-thermo-mechanics coupling to accurately simulate the dynamic characteristics of fast-spectrum micro-reactor core. Based on the open source multi-physics coupling framework MOOSE, a three-dimensional coupled neutronics thermo-mechanics model for the dynamics analysis of fast-spectrum micro-reactors was developed in this paper. The thermo-mechanics coupling was solved by using the JFNK (Jacobian-Free Newton Krylov) method. Then the neutronics model was coupled with thermal-mechanics model by Picard iteration method through the MultiApp and Transfer system based on MOOSE framework. The neutronics solver can directly simulate the neutronics behavior of deformed nuclear reactor configurations including automatic adapting of the cross sections for account for density change. In this paper, this method was applied to the simulation of the supercritical transient of Goidva-Ⅰ with three-dimensional coupled neutronics thermo-mechanics model. Time evolution of fission rate, average temperature rise, surface displacement and surface velocity in the transient with an initial period of 16.2 μs were evaluated. The numerical result of fission rate during the transient was compared with the experimental data, and an overall good agreement was observed. From the numerical results, it can be seen that the fission rate increases, then reaches a maximum value with the positive reactivity introduced. Goidva-Ⅰ is a typical compact, fast-spectrum reactors, reactivity feedback is dominated by core deformation. The quickly accumulated thermal power causes the core temperature increasing, the reactor materials expand, resulting in a larger geometry and reduced material densities. Fission rate then drops due to loss of criticality caused by the thermal expansion. Due to the rapid increase and decrease of fission power, the core is in a state of compression and expansion one after another, and the thermal inertia effect leads to the oscillation of core surface displacement and velocity. At the same time, due to the change of core reactivity caused by deformation, the core power also produces periodic oscillations after 500 μs. The results show that this method can accurately consider the reactivity feedback effect caused by the thermal expansion, which lays a foundation for further multi-physics coupling safety analysis of fastspectrum micro reactors.

The White House Office of Science and Technology Policy (OSTP) issued the public access policy guideline “Increasing Access to the Results of Federally Funded Scientific Research “to require federal agencies with R&D budgets over $100 million for making research papers publicly available. In 2019, the outbreak of the infectious pandemic COVID-19, which caused the global health crisis highlighted the importance of open access. The research outputs which can be accessed immediately, freely, and publicly made great contributions to epidemic tracking and forecasting and accelerated the developments in drugs and vaccines. In 2022, OSTP issued a memorandum on” Ensuring Free, Immediate, and Equitable Access to Federally Funded Research”, expanding the scope of the 2013 Memorandum. The updated OSTP policy guidance expects the research outputs funded by all federal agencies can be accessed more equitably and quickly and support the government in making evidence-based decisions. In this paper, by reviewing the literature on the developments of the U.S. public access policy guidance, to recognize the difference between the two memorandums and it is hoped that libraries can have a better understanding of the global impact on scholarly publishing in the developments of the U.S. policy. Based on the literature findings and observations, this paper provides libraries with suggestions on how to respond to the global changes which are hard to ignore.

This paper collected forum discussions related to archives in mainland China and analyzed the topics and sentiment trends presented in archives posts in 2019-2020. This paper used the NLPIR platform to perform text preprocessing such as word segmentation, part-of-speech tagging, and word frequency statistics. Chinese sentiment vocabulary ontology is then introduced to precede the sentiment analysis. The results showed that the topics that people are most concerned about are generally divided into two types. One is the specific figures and events, the other is the social issues represented by “archival work practice” and “archives access”. In terms of sentiment analysis, the archival affairs forum showed obvious negative emotions when discussing specific people and events; and when it came to the practice of archival work, it showed positive expectations for the archival access.

In this paper, I argue in favor of the view that a generative lexicon, as advanced in lexicalist theories, might not be needed to derive verbal’s argument structure. I instead support the hypothesis that a verb’s meaning emerges as a result of the syntactic structure in which it is merged and that the role of lexical items/roots reduces to their idiosyncratic encyclopedic content. These two assumptions are executed via adopting the proposal that splits the traditional VP structure into two main functional heads, namely VoiceP and vP, and via endorsing the architectural assumptions advanced in the framework of Distributed Morphology. The main empirical support for this claim comes from verbs that appear in syntactic structures that are not in consonance with their semantic-conceptual content, Arabic varieties that lost their vocalic melodies that would otherwise encode thematic roles, and spray-load alternation. This paper concludes by exploring language-particular processes whose non-applicability goes beyond morphology, the analysis of which supports the role of the Encyclopedia.

This paper addresses multiple classifier constructions (MCCs) in terms of internal structure and derivation. Based on a summary of the major features of MCCs, the paper proposes that MCCs are composed of DP and NumP. The combination of the two numeral-classifiers denotes a complete structure, which presents the pattern of double numeral-classifiers. DP serves as the head while NumP serves as the complement. There is no coordination but topic-comment relation between the embedded DP and NumP. The embedded DP c-commands NumP. NumP moves across the board to the specifier position of the external DP to give rise to various types of MCCs. Movement of the classifier of MCCs is triggered by numeral gapping. Based on this, it is argued that all MCCs must be of this nature in terms of the underlying structure. This contention can provide a reasonable solution to many long-standing puzzles related to MCCs.

Low-dose computed tomography (CT) is a relatively safe method for disease screening. But low-dose CT images often contain severe noise and artifacts, which seriously affect the subsequent diagnosis. To solve this problem, this paper proposes a subspace projection and edge enhancement network (SPEENet). SPEENet hold an architecture of autoencoder, including two main modules: dual stream encoder and decoder. The dual stream encoder can be divided into two parts: noise image coding stream and edge information coding stream. The noise image coding stream removes the noise and artifacts in low-dose CT images by using the image features extracted from the low-dose CT images. The edge information coding stream mainly focuses on the edge information of low-dose CT images and fully utilize the edge information to preserve the structures. In order to make full use of the encoder features, this paper introduces the noise basis projection module to establish a basis based on the features of encoder and decoder, and uses this basis to project the features extracted by the encoder into the corresponding subspace to obtain better feature representation. In this paper, experiments are conducted on the public database to verify the effectiveness. The experimental results show that SPEENet can achieve better denoising performance than other low-dose CT denoising networks.

Blood flow is an important physiological parameter of the human body. Real-time measurement of blood flow in the brain, skeletal muscle, and breast tissue is of great significance for disease diagnosis, treatment, surgery, and intensive care. Near-Infrared Diffuse Correlation Spectroscopy (DCS) is a new-type tissue blood flow measurement technology. When using DCS technology for blood flow measurement, the light source-detector (S-D) at each distance contains different degrees of mixed signals of superficial and deep tissues, among which the superficial signals show greater impact on the extraction of blood flow in deep tissues. This paper combines the Nth order linear algorithm (NL algorithm) with the independent component analysis algorithm (Independent Component Analysis, ICA) to separate and process the short-range and long-range optical signals obtained by DCS technology. The computer simulation shows that the algorithm proposed in this paper can better separate the blood flow signals of the superficial and deep tissues, and demonstrates important potential for the application of DCS technology in clinical blood flow measurement in the future.

Dynamic monitoring and quantitative estimation of forage crop growth are of great importance to the large-scale production of forage crop. UAV remote sensing has the advantages of high resolution, strong flexibility and low cost. In recent years, it has developed rapidly in the field of forage crop growth monitoring. In order to clarify the development status of forage crop growth monitoring and find the development direction, first, methods of UAV crop remote sensing monitoring were briefly described from two aspects of data acquisition and processing. Second, three key technologies of forage crop including canopy information extraction, spectral feature optimization and forage biomass estimation were described. Then the development trend of related research in recent years was analyzed, and it was pointed out that the number of papers published on UAV remote sensing forage crop monitoring showed an overall trend of rapidly increasing. With the rapid development of computer information technology and remote sensing technology, the application potential of UAV in the field of forage crop monitoring has been fully explored. Then, the research progress of UAV remote sensing in forage crop growth monitoring was described in five parts according to sensor types, i.e., visible, multispectral, hyperspectral, thermal infrared and LiDAR, and the research of each type of sensor were summarized and reviewed, pointing out that the current researches of hyperspectral, thermal infrared and LiDAR sensors in forage crop monitoring were less than that of visible and multispectral sensors. Finally, the future development directions were clarified according to the key technical problems that have not been solved in the research and application of UAV remote sensing forage crop growth monitoring: (1) Build a multi-temporal growth monitoring model based on the characteristics of different growth stages and different growth years of forage crops, carry out UAV remote sensing monitoring of forage crops around representative research areas to further improve the scope of application of the model. (2) Establish a multi-source database of UAV remote sensing, and carry out integrated collaborative monitoring combined with satellite remote sensing data, historical yield, soil conductivity and other data. (3) Develop an intelligent and user-friendly UAV remote sensing data analysis system, and shorten the data processing time through 5G communication network and edge computing devices. This paper could provide relevant technical references and directional guidelines for researchers in the field of forage crops and further promote the application and development of precision agriculture technology.

As one of the important way for constructing smart agriculture, unmanned farms are the most attractive in nowadays, and have been explored in many countries. Generally, data, knowledge and intelligent equipment are the core elements of unmanned farms. It deeply integrates modern information technologies such as the Internet of Things, big data, cloud computing, edge computing, and artificial intelligence with agriculture to realize agricultural production information perception, quantitative decision-making, intelligent control, precise input and personalized services. In the paper, the overall technical architecture of unmanned farms is introduced, and five kinds of key technologies of unmanned farms are proposed, which include information perception and intelligent decision-making technology, precision control technology and key equipment for agriculture, automatic driving technology in agriculture, unmanned operation agricultural equipment, management and remote controlling system for unmanned farms. Furthermore, the latest research progress of the above technologies both worldwide are analyzed. Based on which, critical scientific and technological issues to be solved for developing unmanned farms in China are proposed, include unstructured environment perception of farmland, automatic drive for agriculture machinery in complex and changeable farmland environment, autonomous task assignment and path planning of unmanned agricultural machinery, autonomous cooperative operation control of unmanned agricultural machinery group. Those technologies are challenging and absolutely, and would be the most competitive commanding height in the future. The maize unmanned farm constructed in the city of Gongzhuling, Jilin province, China, was also introduced in detail. The unmanned farms is mainly composed of information perception system, unmanned agricultural equipment, management and controlling system. The perception system obtains and provides the farmland information, maize growth, pest and disease information of the farm. The unmanned agricultural machineries could complete the whole process of the maize mechanization under unattended conditions. The management and controlling system includes the basic GIS, remote controlling subsystem, precision operation management subsystem and working display system for unmanned agricultural machineries. The application of the maize unmanned farm has improved maize production efficiency (the harvesting efficiency has been increased by 3－4 times) and reduced labors. Finally, the paper summarizes the important role of the unmanned farm technology were summarized in solving the problems such as reduction of labors, analyzes the opportunities and challenges of developing unmanned farms in China, and put forward the strategic goals and ideas of developing unmanned farm in China.

This paper described the concept and basic satisfaction of scientific and technological revolution, defines the endogenous and exogenous agricultural disruptive technology. The revolution of agricultural science and technology refers to the process in which the key disruptive core technology innovation applied to agricultural production drives a series of technological innovations adopted in production. Endogenous disruptive technology in agriculture refers to technology indicators that can fundamentally change the original technology, such as productivity improvement, overturn the economic or social necessity of the adoption of the original technology, and completely replace the original technology. Particularly the paper puts forwards the concept of the transboundary technology and demonstrates its endogenous application and impacts on the development of agricultural industry. The transboundary technology for exogenous application refers to the technology whose original invention and innovation are applied in non-agricultural fields and has nothing to do with agricultural industry. Focusing on smart agriculture and the typical transboundary technology, the paper analyzed the characteristics of the smart agriculture, discussed its impacts on the traditional agricultural production and rural transformation. Smart agriculture technology will be the disruptive core technology to promote a new round of technological and industrial revolution and rural transformation. It will fundamentally change the production mode of traditional agriculture, realize factory production and promote the revolutionary transformation of rural areas. The production and application of smart agricultural technology in China has shown good economic and social benefits and great potential for production and application. However, the application of intelligent agricultural technology based on artificial intelligence technology is still in the exploratory stage. As an agricultural application of transboundary technology, the smart agricultural technology with intelligent sensing technology as the core is not dominated by agricultural scientists like agricultural machinery technology revolution, chemical technology revolution and green revolution technology. At present, the application smart agriculture technology in China is only in its infancy. Hence, policy recommendations of strengthening key disruptive technology development, reforming agricultural higher education system, promoting the agricultural industry development of the transboundary technology, and pushing the application of smart agriculture technology to be implemented in high standard farmland and large-scale farms of agricultural production, etc., were proposed to promote the development of smart agriculture.

ObjectiveCargo loading and unloading plan generation time and safety evaluation have a great influence on the handling efficiency. To this end, this paper introduce weight coefficient searching genetic algorithm into the plan generation. MethodsLoading safety status mainly involves draft limitation, intact stability checking, hyrostatic strength checking and compatibility between the generated loading and unloading plan and preset process. In this study, a non-deterministic polynomial and corresponding optimization objective functions are established to solve the loading and unloading scheme generation problem of liquid cargo carriers. The weight of each influence factor in the objective function is changed and recorded in sequence to form an optimal objective function cluster. The optimal solution of each member in the cluster is then carried out through an elitist preservation genetic algorithm in order to provide an optimal solution set. On this basis, a comparison is made with the loading and unloading plan of a very large crude oil carrier (VLCC) generated by the linear fitting methodResultsThe ship draft status is more consistent with the target, and the stability state is obviously better than that of the user preset plan in each loading/unloading step generated by this algorithm. ConclusionThe weight coefficient searching genetic algorithm based on elitist preservation proposed in this paper can improve the accuracy and reliability of the liquid cargo carrier loading sequence.

ObjectiveThe purpose of this paper is to explores the water-entry slamming load distribution of a trimaran connecting bridge.MethodsBased on OpenFOAM open source software and starting with the continuity equation and N-S equation, this paper establishes a free entry slamming numerical model of a trimaran connecting bridge. The dynamic changes of velocity, slamming pressure and free surface during the free entry slamming process of the trimaran connecting bridge are simulated. The convergence analysis of the grid is carried out, and the numerical solution is compared with the experimental solution to verify the accuracy of the numerical calculation method. ResultsThe results show that this method can effectively predict the falling body slamming load of a trimaran connecting bridge structure. It is found that the slamming pressure coefficient of the connecting bridge is largest near the outer corner. The peak value of the slamming pressure on the lower surface of the connecting bridge and the relationship between the slamming pressure coefficient and velocity are then obtained.ConclusionsThis study presents the characteristics and range of slamming pressure on a trimaran connecting bridge, providing a numerical basis for the structural strength evaluation and design of trimarans.

ObjectivesIn order to solve problems such as bad weather conditions, remote routes, long rescue time and no suitable port of call for rescue supplies, which are unique to polar routes and not conducive to personnel safety, this paper presents a design concept in which the polar cruise ship itself is the best lifeboat in the event of fire or flooding, and discusses an electrical system design method for realizing this concept.MethodsThis paper analyzes the characteristics of the polar route environment, summarizes risks and countermeasures, combines the Safe Return to Port (SRtP) concept and proposes the functional goals of important electrical systems in order to guarantee the power and personnel safety of polar cruise ships. It then provides the topology for the design of redundant electrical systems and analyzes the design scheme of typical systems combined with the realized design objectives and philosophy. Results In the design and construction of small polar cruise ships, the design principle of double redundancy or isolation should be adopted as far as possible in order to achieve the design goal of maintaining the operation of important electrical systems after accidents, thereby greatly improving the life safety guarantee of cruise ship personnel. ConclusionThis paper can provide ideas and references for the electrical system design of small polar cruise ships.

ObjectiveThe prediction of supporting resources has always been a focus and difficulty of naval ship comprehensive support. In this paper, a prediction model and method are proposed for the support needs of naval ship maintenance docks. MethodThe Markov process is introduced and applied to the prediction of ship dock demand. By analyzing the system characteristics of ship dock use, a Markov forecasting model and evaluation index of dock demand are established, and the validity of the prediction method is verified by case analysis. ResultsThe calculation example shows that the prediction model can better reflect the influence of ship maintenance intensity and the number of docks on the system state, and the optimal dock requirements reflected by the evaluation index are in good agreement with the actual engineering. ConclusionThe prediction model of ship repair dock demand proposed in this paper can better reflect the physical process and engineering practice, and provide theoretical support for decision analysis, giving it good practical significance.

ObjectiveThe exhaust ejection device is an important part of a ship's gas turbine intake and exhaust system. It is very important to ensure the exhaust and ejection performance of the exhaust ejection device for the normal operation of the ship. MethodsAccording to the characteristics of this type of gas turbine exhaust ejection device, this paper selects eight relevant structural parameters and two objective functions in order to analyze the parameter correlation, and determines the two design variables that have the greatest correlation with the objective function. On this basis, the design parameters are optimized based on the multi-objective optimization genetic algorithm NSGA-II, and the selected optimization scheme is applied to a gas turbine intake and exhaust system assembly model for verification. Results The results show that, compared with the original scheme, the optimized exhaust ejection device has a significantly improved ejection flow rate of the gas turbine casing, meeting the design requirements of the exhaust ejection amount, but this also leads to an increase in exhaust back pressure. ConclusionThe research approaches and results obtained in this paper have certain reference value for the design and optimization of gas turbine exhaust ejection devices.

Flow boiling is widely encountered in many industrial fields such as the steam generator in nuclear reactors. Nowadays, a lot of studies are focused on the bubble dynamics parameters due to the close relationship between the heat transfer and bubble behaviors. Bubble departure frequency is one of the important bubble dynamic parameters which reflects the bubble cycle in time and thus directly influences the bubble evaporation heat. In order to improve the predicting accuracy of bubble departure frequency and thus improve the accuracy of heat transfer calculation under flow boiling, the affecting factors of bubble departure frequency firstly through 13 groups of flow boiling independent experiments of water (506 experimental data points) were analyzed in this paper. It is found that bubble departure frequency decreases with the increasing of liquid subcooling, while it increases with the increasing of channel size, mass flux, wall superheating and pressure in which the effect of channel size is often ignored by many researchers. Then the accuracy of five existing prediction models was evaluated. The results show that none of them have high prediction accuracy in all experimental data points. Cole model and Zuber model both perform badly and have the absolute errors of 163.2% and 218.2% respectively and the relative errors of 134.2% and 205.1% respectively, because they only consider the effect of physical properties and thus they are more suitable for pool boiling. Brooks model and Basu model both overestimate the results with the absolute errors of 280.2% and 102.1% respectively and the relative errors of 2352% and 37.1% respectively. The reason lies in that these two models are developed through their own experiment data and thus have limited application ranges. Chen model performs relatively better with the absolute error of 64.8%, but it largely underestimates the results with the relative error of -52.3% for the reason that this model is developed based on the pool boiling experiments of methane and ignored the effects of mass flux and liquid subcooling. Besides, the results show that most predicting models perform badly when the channel size is small which confirm the significant influence of channel size. Therefore, in this paper, a new prediction model was developed with higher predicting accuracy through dimensionless analysis which consideres the effects of channel size, physical properties, wall superheating and mass flux. This new model has the mean absolute error of 39.2% and mean relative error of -14.3% with the application ranges of bubble Reynold number 28-2 303, Bond number 1-9.272 and Jakob number 0.004-0.049.

In the two-phase flow system, the flow pattern affects the frictional resistance and heat transfer characteristics of the system. Accurate identification of different flow patterns is of great significance to the calculation of twophase flow. For the gasliquid flow in narrow channels, especially the flow pattern and flow pattern transition criterion in rectangular narrow channels, some researchers have done some experimental studies. For the study of flow pattern in narrow rectangular channels, the classification of flow patterns is basically consistent with that in conventional rectangular channels, including bubbly flow, slug flow, churn flow and annular flow. However, the performance of existing flow pattern transition criteria for twophase flow in narrow rectangular channels still needs further and comprehensive assessments. In this paper, a parameter representing the success rate of boundary separation of bubblyslug flow transition was introduced to quantitatively evaluate the performances of five typical bubbly-slug flow transition criteria and experimental data reported by 10 previous researchers, covering channel sizes ranging from 0.6 mm to 30 mm. Results show that the success rate of boundary separation of the Jones & Zuber criterion, Taitel criterion, MishimaIshii criterion and Xu criterion in predicting the experimental data varies from 61.86% to 98.10%. The variation mainly attributes to the assumption of constant critical void fraction in these criterions, since analyzing shows that the critical void fraction of flow pattern transition is related to the channel geometry. Although the HibikiMishima criterion considers the effect of channel size on the critical void fraction, the bubbly diameter (Db) is also needed in this model, which is difficult to obtain. The influence of channel size on the flow transition was quantitatively analyzed based on a dimensionless parameter of confinement number (Co). Finally, the flow pattern transition function (f(k)) was correlated with Co, and a new flow pattern transition criterion of bubbly-slug flows in narrow channel considering the physical properties of working fluid and the size of flow channel with higher accuracy and wider application range was established, which predicts the experimental data with success rates of boundary separation of 83.78% to 98.10% within the range of 0.486 57≤Co≤1.471 04, 0.016 m/s≤jg≤6.758 m/s, and 0.058 m/s≤jf≤5.059 m/s. The conclusions of this paper can provide references for the design and optimization of reactor heat exchanger components and compact heat exchangers.

Advanced nuclear reactors are currently moving toward longer fuel cycles and higher burnup levels. Besides, high burnup levels can improve fuel economy and reduce the total amount of spent fuel in reactors. The formation of high burnup fuel particle is closely related to the failure behavior of ceramic dispersion fuel, and it is of great significance to focus on the strength analysis and cracking behavior of high burnup fuel particle. The representative volume element of dispersion fuel was innovatively established in this paper, and the heterogeneity of pore size and position in high burnup fuel particle was considered, corresponding parametric modeling and mechanical simulation procedure of high burnup fuel particle was realized automatically. The impacts of mechanical property of matrix, distance between fuel particles, ambient hydrostatic pressure and damaged layer on the strength of the fuel particles were analyzed systematically. The results show that the distance between fuel particles increases, the less possibility of crack initiates from the fuel particle. The existence of damaged layer will increase the risk of cracking of the fuel particles slightly. Due to the stress interference of the heterogeneous pores, crack initiates from multiple sites within the fuel particle, and the danger zones are more possibility located at the outer space, which is consistent with the experimental observations. Besides, danger zones within the high burnup fuel particle were characterized by larger pores and pore strings. It can be inferred that the formation of larger pores is probably due to the continuous coalescence of small pores and their surrounding pores. The constraint pressure of matrix on the fuel particle is not a constant, specially, it fluctuates significantly, and its average value increases linearly with the ambient hydrostatic pressure. Increasing the elasticity modulus of the matrix will inhibit the cracking behavior of the fuel particle, which reveals that the matrix should be designed more stronger and tougher. The higher the ambient hydrostatic pressure, the less likely the fuel particle will crack. While shortening the distance between fuel particles, and the impact degree of ambient hydrostatic pressure reduces. This work realizes the accurate calculation of the internal stress field of high burnup fuel particle and establishes a high burnup fuel cracking strength evaluation model based on fine microstructure modeling. Besides, this paper provides an analytical method and numerical reference for the failure study and optimal design of dispersion fuel under high burnup conditions.

Nuclear thermalpropulsion reactor has attracted more and more attention because of its long service life, strong mobility and high concealment. However, in order to achieve higher mobility, nuclear thermalpropulsion reactor reduces its weight and does not have perfect radiation shielding measures, which will cause a lot of radiation to the external environment after operation. The radiation has an important impact on the application and development of nuclear thermal propulsion reactor. Therefore, it is necessary to study its radiation characteristics. This paper studies the radiation caused by the radioactive fission products produced after the operation of “Pluto” TORY ⅡC reactor published by the United States in the last century, ignoring the direct radiation of chain fission reaction, the radioactivity of component activation and the leakage of radioactive gas. Firstly in this paper, the burnup products of the reaction after 10 hours of full power operation were calculated by Monte Carlo method and the energy spectra of 106 radionuclides with high radioactivity were calculated, including Xray, gamma ray, bremsstrahlung and spontaneous fission gamma ray. Then the radiation field outside the reactor was calculated by pointkernel integral method. Because the pointkernel integral method has higher accuracy in calculating the simple structure, the reactor geometry was simplified in calculating the radiation field in this paper. The calculation results show that the reactor consumes 056% 235U after operation. The radioactivity increases gradually with time and finally reaches 1298×1021 Bq. Gamma radiation accounts for the main part. The maximum dose rate on the outer surface of TORY ⅡC shielding layer can reach 67185 Sv/h. Because the rear reflection layer is the thinnest and the side reflection layer is the thickest, the dose rate at the tail is the highest and the side dose rate is the lowest. At the same time, the calculated radiation field maintains a high dose rate in a large range. Therefore, this paper concludes that TORY ⅡC will produce a large amount of radiation after operation. Radiation shielding facilities must be installed to reduce the area of high radiation area, protect the environment and ensure personnel safety. At the same time, this paper calculates that the burnup products are regarded as uniform distribution and compares them with the previous accurate calculation results. It is found that there is little difference between the two calculation results in a far position. It can be inferred that when the distance is far enough, the two calculation results will be infinitely close. When the accuracy is not pursued, the burnup products can be regarded as uniform distribution to simplify the calculation and speed up the calculation time.

The complex cosmic thermal environment is a great challenge to the orbit injection of space reactors. Improper design will lead to liquid metal condensation and hinder the safe start-up of reactors. Therefore, for the safe start-up of liquid metal cooled space reactor, the liquid metal in the system must be insulated to prevent condensation on orbit. In this paper, the onorbit insulation strategy of space thermionic reactor was proposed and a model was established for calculation and verification. In order to simulate the influence of space thermal environment and verify the insulation strategy, this paper established a improved TOPAZ Ⅱ space thermionic reactor model based on the transient analysis code of space thermionic reactor system, TASTIN. The calculation model was divided into several control volumes. For each control volume, the governing equations were discretized based on the finite volume method (FVM), and the transient equations were solved by Gear algorithm. Moreover, the radiator heat transfer model (TASTIN-RAD) and the radiant heat transfer model of the heat shield (TASTIN-SHIELD) were developed for calculation of thermal environment (mainly solar heat flux) and different heat shields respectively. Then the spin and non-spin states of the space reactor on orbit were calculated with considering the solar heat flux. The results show that the spin state is better than the non-spin state in the first flight cycle, while in the subsequent flight cycle, the nonspin state is better than the spin state. After 24 hours’ flight of nonspin in orbit, the temperature of fluid is close to the freezing point and additional thermal insulation measures shall be taken. Thus, different insulation strategies including open and closed heat shields are calculated and analyzed in nonspin state for 24 hours flight. By adding an open heat shield, the solar heat flux has a significant heating effect on the fluid. The minimum temperature of the fluid after 24 hours of flight is 295 K, which can ensure that the fluid does not solidify. Under the closed heat shield scheme, the top of the heat shield has a special absorption emission ratio, which can heat the system circuit. After 24 hours orbit flight, the minimum temperature of the circuit fluid reaches 303 K. According to the calculation results, only depending on the flight attitude and the heating effect of solar heat flux is not enough to prevent the condensation of liquid metal working medium, so additional insulation measures must be added. Both insulation schemes proposed by this paper effectively ensure the long-term heat dissipation of the system and have high safety margin. The difference is that the closed shield strategy can make the fluid temperature rise slowly, while it decreasing in the open shield strategy, which means the close shield strategy has absolute security. The calculation results of this paper provide a basis for the insulation scheme design of space thermionic reactor.

ObjectiveA ship's system is a complex mechanism composed of multiple pieces of equipment. Due to the dynamic and non-linear characteristics of the parameters of each component, fault diagnosis is complicated. This paper proposes a dynamic feature fusion method for performing efficient fault diagnosis on the system.MethodsFractal theory, dynamic theory and the kernel principal component analysis (KPCA) method are used to reconstruct, map and filter the system state data, and obtain the principal component characteristic data matrix, square prediction error (SPE) and corresponding control limits. An offline monitoring model based on the health data of a marine diesel engine intake and exhaust system is then constructed and used to diagnose and analyze ship system faults. In order to verify the validity of the model, the fault data of the intake and exhaust system of a marine diesel engine is selected for verification and analysis. ResultsThe results show that this method can effectively realize the accurate analysis of a system's dynamic nonlinear state data and efficient analysis and diagnosis of faults, with better fault diagnosis performance than the KPCA and support vector machine (SVM) method.ConclusionsThe method proposed in this paper can realize the detection and diagnosis of marine diesel engine intake and exhaust system failures, and improve the reliability and safety of system operation.

The traditional named entity disambiguation technology usually relies on rich context and knowledge of external entities. However, many emerging entities lack knowledge bases and the text containing entities is short. These limitations make traditional algorithms unable to make full use of contextual semantic information. At the same time,due to the limitation of the number of effective samples, the final application scenarios of the algorithm are very limited. Based on the above defects, this paper proposes a deep learning-based entity disambiguation method combining bidirectional encoder representation from transformers(BERT) model and long short-term memory neural network.The main work are the following parts: 1) A word vector based on the BERT model is designed to obtain more information through fewer data samples. 2) In order to allow the long short-term memory neural networks to retain useful information and verify that the short text applies to the method of this article, this method segments the sentence samples. 3) This article uses the neural network intelligence(NNI) technology proposed by Microsoft, which makes it possible to quickly and efficiently obtain the optimal neural network hyperparameter. This study compares other different types of word vectors and neural network technology, confirming that the F-Measure value of the entity disambiguation technology based on deep learning used in this paper is higher.

In order to fully understand the current research situation in field of deep coal mining, took the relevant literature of web of science database from 2003 to 2021 as a sample, this paper made an in-depth analysis on the number of papers issued, research institutions, countries, authors, literature citations, keywords and disciplines.The results showed that China's research level is at the forefront of the world in terms of the number of papers issued, research institutions and national levels; Chinese scholars pay high attention to this field in terms of the author; highly cited documents are mostly engineering and technical studies in terms of literature citation; from the perspective of keyword development and evolution, the keywords in this field mainly focus on model, rock, numerical simulation, mechanism and stress, model and numerical simulation will be the important research methods in this field in the future.From the perspective of discipline development and evolution, disciplines in this field mainly focus on engineering, geology, multidisciplinary geoscience, energy and fuel, environmental science and ecology, sustainable development will become the hot research directions in the future.

Firstly, this paper expounds the research status at home and abroad of three key technologies in the production process of fresh and wet rice flour: efficient powder dispersion, accurate weighing and automatic packaging, and focuses on the key technical problems existing in the research and development of technology and mechanical equipment; Secondly, on the basis of summarizing the development level of existing technology and equipment, this paper further analyzes the main reasons for these problems. Finally, the development direction of three key technologies in the automatic production of fresh and wet rice flour is prospected from the aspects of production technology, mechanical design and system algorithm optimization.

The rise of open access mega journals has significantly changed the modern academic publishing industry. Mega journals adopt low-selective peer review standards, whereby peer reviewers only evaluate the soundness and ethics of research and no longer pay much attention to novelty, importance, and applicability. The academic community is concerned that this will make the quality of published works vary excessively and even make mega journals become a “dumping ground” for low-quality research. Given the lack of Chinese-language literature on mega journals, this study applies a literature review method to analyze the impact of mega journals on academia. This article first reviews the origins of mega journals and the main differences between them and traditional peer-reviewed journals; the paper also explicates the diverse viewpoints and discussions on mega journals in the international scientific communities. Finally, from the perspective of research integrity, this paper proposes practical guidance that research stakeholders might follow to respond to the prevalence of mega journals. It is hoped that the results of this research can serve as a reference for the higher education community in Taiwan.

Based on the mathematical model of internal air flow, heat and humidity coupled transfer in paddy grain piles, while combined with the dynamic model of paddy yellowing, the paper adopted the method of numerical simulation to compare and study the variation of temperature, moisture content and paddy yellowing in the stored grain inside the shallow round warehouse under the conditions of annual natural storage and staged natural storage. On the basis of temperature and humidity, this paper further considered the yellowing effect on the quality of long-term storage of paddy. The results showed that, at the end of storage for 365 days, the average temperature of staged natural storage with ventilation was about 18 ℃ lower than that of natural storage throughout the year, the average moisture was about 0.5% lower, and the average yellowing value was about 0.8 lower. Low temperature air flowling into the high temperature granary could not only reduce the temperature, but also reduce the grain moisture and alleviate the process of paddy yellowing, so the phased natural storage was more conducive to the long-term quality storage of paddy. The rice near the warehouse wall was easily affected by the external ambient temperature, and the coating could be applied on the outside of the warehouse wall to reduce the influence of solar radiation.

In the process of long-term operation of steam generators, although the secondary side of the water quality is strictly controlled, in the complex thermal hydraulic conditions, impurities will also accumulate in the steam generator. It mainly includes the deposition of the heat transfer tube and the blocking of the tube support plate. Among them, the deposition of impurities on the supporting plate will cause the blocking of the tube support plate. The blockage of the support plate may lead to local highspeed flow and cross flow in steam generators, which will cause flowinduced vibration and tube cracks in some situations. Therefore, it is necessary to study the deposition of the tube support plate. In order to predict the deposit distribution on the tube support plate of the steam generator, the impurity migration model and the tube support plate flow blockage model were added to the threedimensional thermohydraulic code of the steam generator STAF developed by NuTHeL of Xi’an Jiaotong University. The accuracy of the code, which was based on a porous medium method and the drift flux model, has been fairly well verified. The deposition on the tube support plate with and without ageing for 150 days were predicted in the paper. Then the influence of ageing was studied. First of all, the results show that there are more deposits in the upper part of the hot side of the tube support plate, which suggests that boiling is the main factor leading to deposition. Compared with the situation without ageing, the mass of deposits after ageing is reduced, and the difference of the deposition mass between the hot and cold sides is also significantly reduced. In addition, ageing also has a certain effect on the distribution of deposits. After ageing, the distribution of deposits is closer to the two sides of the tube support plate, which is similar to the distribution of flow velocity. The reason for this phenomenon is that flash evaporation is more likely to occur where the flow rate is high, making the soluble precipitate and thus exacerbating the ageing. The research of this paper can provide reference for the design and cleaning of steam generator in nuclear power plant. In practical applications, we can take some measures through the program prediction to reduce the harm caused by the tube support plate clogging. In the future work, we will continue to study the influence of tube support plate blockage.

58Co and 60Co are the primary radionuclides and contributors to collective dose of PWRs, which may exist in ionic, particle and colloidal state in the primary loop. The pore diameter of the most advanced filter used in chemical and volume control system (CVCS) in domestic PWRs is 0.1 μm, the removal efficiency of Co colloids with the diameter of less than 0.1 μm is very low. Activated corrosion products such as Co colloids may deposit on the surface of the primary loop and auxillary systems during shutdown, contributing to collective dose. The chemical conditions of primary loop during the oxidation operation process greatly affect the removal efficiency of radionuclides such as Co colloids. To achieve the best dissolution and removal effect of Co colloids, the dissolution behavior of Co colloids need to be studied. In this paper, simulated Co colloids were first synthesized in the laboratory. The average particle size of simulated Co colloids was characterized by TEM to be 40-50 nm. The composition of simulated Co colloids was characterized by TEM, SEM and EDS as CoO and Co. Then the effects of temperature (60-80 ℃), Li concentration (pH, 0.1-3 mg/kg), H2O2 concentration (0.20 mg/kg) and reaction time (0-6 h) on the dissolution behavior of Co colloids were investigated on simulated chemical condition of the oxidation operation process. The results show that the dissolution of Co colloids is quite fast, reaching reaction equilibrium in 0.5-1 h. The dissolution behavior of Co colloids is affected by temperature, Li concentration and H2O2 concentration. The dissolution of Co colloids is promoted by addition of H2O2 due to the weak acidity and strong oxidizing power of H2O2. However, too much H2O2 is unfavourable for the dissolution of Co colloids, which may be due to the possible formation of passive film on Co colloids. Low Li concentration or low pH is favourable for the dissolution of Co colloids. The oxidizing power of H2O2 is stronger at higher temperature promoting the dissolution of Co colloids. Yet high temperature is not favorable for the dissolution of Co colloids, as the dissolution of Co colloids is an exothermal process. Therefore a moderate temperature is the best choice for the dissolution of Co colloids. To summarize, the best chemical condition for the dissolution and removal of Co colloids during the oxidation operation process is at 70 ℃ with as low Li concentration as possible and about 10 mg/kg H2O2. The results in this paper provide important references for the improvement of the oxidation operation process of PWRs.

With the constant development of power, information and other technologies, the advantages of unmanned ships are emerging in anti-mine, anti-submarine, electronic warfare, maritime security, maritime interception, and other military fields. This paper describes the development of unmanned ships and power technology and clarifies that the integrated power system has become a major trend of medium and large-sized unmanned ships. It also introduces the application of integrated power system in manned and unmanned platforms, and proposes that issues like size, weight, and control of vibration and noise are of essential for the integrated power system for unmanned platforms. In the end, this paper summarizes the trend of integrated power technology for unmanned platforms and identifies the key scientific problems of integrated power technology on unmanned platform, namely the intelligent operation of integrated power system, high-performance motor materials, information perception of complex motor system, power electronic device and system, high-performance power conversion and efficient energy storage.

ObjectivesThis paper aims to address the numerical simulation problems of the dynamic response of ships subject to near-, medium- and far-field underwater explosions by establishing several numerical methods and calculation models. MethodsFirst, load and fluid-structure interaction models are established on the basis of the Eulerian finite element method and acoustic finite element method using the field-split technique, and FSLAB fluid-structure interaction software is developed. Next, near-, medium- and far-field underwater explosions are numerically simulated respectively. The shock wave propagation law, bubble shape and load evolution characteristics of near free-surface and near-wall underwater explosions are obtained, and the shock response characteristics of a spherical shell and ship subject to far-field underwater explosions are analyzed. Finally, the FSLAB software results are compared with the analytical solutions, reference solutions and experimental data. ResultsThe results show that the FSLAB fluid-structure interaction software developed in this paper is effective and accurate in simulating the impact damage of underwater explosions on warships. ConclusionThis study can provide a basis and support for the power assessment of underwater anti-explosion and shock design of warships.

The plate-type fuel assembly with the advantages of high specific power of active zone and compact structure has been widely adopted in many research reactors and material irradiation test reactors. The narrow rectangular channel in platetype fuel assembly has the geometric characteristics of large aspect ratio, resulting in large gradient and steep distribution of velocity in the height direction. When the subcooled boiling occurs, the bubble behavior near heated wall will be affected, and the bubble sliding phenomenon has a great influence on the boiling heat transfer. In this paper, a wall heat flux distribution model considering the sliding heat flux was built and quenching heat flux was redefined as the sensible heat released by the solid wall under the dry spot. The bubble stress analysis model and sliding model based on theoretical and semi-empirical expressions were established to calculate essential auxiliary parameters including bubble departure diameter, lift-off diameter and sliding distance. A wall boiling model suitable for upward flow boiling in the narrow rectangular channel was developed. After that, the numerical simulations under different operating conditions were performed against the Nuthel flow boiling experiments in narrow rectangular channels for model verification. The results show that the model developed in this paper can better predict the wall superheat degree of upward flow boiling in the narrow rectangular channel under medium and low pressure conditions in the range of 1-4 MPa. Compared with the RPI model, the wall temperature calculated by the developed model in this paper is much higher, and the maximum error of wall superheat in the boiling region decreases from 80% to 17% in the simulated conditions, indicating that the wall boiling model considering the sliding heat flux can describe the flow and heat transfer characteristics of upward flow boiling in the narrow rectangular channel more accurately. As for the heat flux distribution, the sliding heat flux and single-phase convective heat flux calculated by developed model take up significant fraction, and evaporation heat flux is less significant. The quenching heat flux, defined by the reconstructed expression, is almost negligible, which demonstrates that the sensible heat released by the solid wall under the dry spot has little influence on the overall heat transfer process. In RPI model, however, evaporation heat flux accounts for the majority of the total heat flux in the boiling region. Lower fraction of heat flux allocated to evaporation heat flux leads to less evaporation rate and predicted void fraction.

The power system of heat pipe cooled nuclear reactor can be divided into dynamic conversion system and static conversion system. Thermoelectric generator (TEG) is a typical static conversion device, which can directly convert heat energy into electric energy. The combination of heat pipe cooled nuclear reactor and TEGs can bring many advantages, such as compact structure, high inherent safety, no auxiliary mechanical equipment and low noise. However, the maximum core temperature could exceed 1 000 K, and ordinary thermoelectric generators can not operate in such high temperature. To solve this problem, the use of segmented thermoelectric generator (STEG) in the power system of heat pipe cooled nuclear reactor is a method worthy of research. STEG can play an important role in the heat pipe cooled nuclear reactor. But there is not enough literature to study the application of STEG in heat pipe cooled nuclear reactor. STEG usually splices two or three thermoelectric materials with the highest power generation efficiency in different temperature ranges. In this way, STEG can obtain a high thermoelectric conversion efficiency in a wide temperature range (usually above 600 K). Therefore, a kind of STEG for heat pipe cooled nuclear reactor was designed. In this paper, a conceptual design of a heat pipe cooled nuclear reactor with STEGs was proposed. The single STEG and single channel model were explored by COMSOL software. A three-dimensional finite element model of STEG’s performance in heat pipe cooled nuclear reactor was established. STEG was designed to compose of bismuth telluride and skutterudite, and its geometric structure and performances were optimized. Numerical simulation was carried out under steady-state conditions to determine the optimal STEG’s geometry. Then, the optimized STEG was connected with the heat pipe to form a single channel model for simulation to explore its performances. When the temperature difference reaches 550 K, the maximum STEGs’ output power reaches 0.374 W, and the maximum conversion efficiency is 15.75%. In single channel model, when the heating power is 300 W, the maximum STEGs’ output power reaches 47.29 W, and the maximum conversion efficiency is 15.63%. The simulation also show that the maximum stress of single STEG and single channel model are 270 MPa and 547.5 MPa, respectively. And the maximum stress appears on the copper conductor near the hot side. This paper could provide a preliminary basis for the numerical simulation of the combination of STEG and heat pipe cooled nuclear reactor. This paper can also be used as a reference for the thermoelectric conversion of heat pipe cooled nuclear reactors.

X-ray detectors made by optical fiber coupled with full-frame CCD are widely used in highprecision X-ray CT scanning of laboratory. Because of the strong penetration of Xrays, the conventional shutter can’t realize ray shielding, so the fullframe CCD detector usually works in the shutterfree mode which can’t avoid generating image smears. Due to image smears, the image observation is seriously affected and the dynamic range of effective data of the CCD detector is reduced. The smears of projection images of fullframe CCD detector must be corrected. In order to correct smears of projection images in CT scanning application, the characteristics of image smear of fullframe CDD in standard readout mode and charge flush readout mode were studied in this paper. And the applicability of the widely used smear correction method using line pixels data of the optical black region to the smear correction of Xray radiation imaging was studied too. It is found that the application of dark pixels correction method to correct the radiation projection image may bring thin strip artifacts. The results come from two main reasons. Firstly, the fluctuation of pixels data can’t be effectively suppressed by calculating the mean value, because the number of lines of pixels data of the optical black region is too small. Secondly, the fluctuation of line pixels data of the optical black region will increase due to the radiation interference during integration. An improved smear correction method using nonexposed line pixels data was proposed in this paper to avoid the two shortcomings above. Using this method, the image smear is corrected by using the nonexposed line pixels data which aren’t exist during integration, so the radiation interference during integration is well solved. In addition, the stability of correction data is improved by calculating the mean value of more nonexposed line pixels data because the number of nonexposed line pixels data can be customized on demand. Further study of dynamic exposure CT scanning imaging shows that the correlation between the smear charges and the exposure charges of the readout image has changed due to the change of the position of the measured sample during exposure and image readout. Therefore, the image smears of dynamic exposure can’t be suppressed by conventional image correction. In order to solve the problem of correcting the smear in dynamic exposure imaging, a ROI fast readout mode based on radiation shielding was proposed, which can effectively suppress the generation of image smear by shortening the transfer time of the integral charge. The experimental results show that the smears of DR image are effectively suppressed, and the quality of the projection image is improved, when applying smear correction method proposed in this paper to static exposure CT scanning. And when applying the ROI fast readout mode proposed in this paper to dynamic exposure CT scanning, the smears of DR image are suppressed, the dynamic range of effective data of the detector is improved, and the problem of image smear correction for dynamic exposure imaging is effectively solved.

As a novel radar system, the Multiple-Input Multiple-Output (MIMO) radar with waveform diversity has demonstrated excellent performance in several aspects, including target detection, parameter estimation, radio frequency stealth, and anti-jamming characteristics. After nearly 20 years of in-depth research by scholars, the MIMO radar theory based on orthogonal waveforms has significantly improved. It has been widely applied in fields such as automobile-assisted driving and safety defense. In recent years, with the introduction of the concepts of electromagnetic environment perception and knowledge aid, and the application requirements of radar-active anti-jamming, radio frequency stealth, and detection-communication integration, multiple new theories and methods have been generated for the MIMO radar in system architecture, transmit waveform design, and signal processing. This paper aims to review and summarize the research works on MIMO radar published in the past 20 years, including: the principle of the orthogonal-waveform MIMO radar, its target detection performance analysis and typical applications; waveform design and characteristics of the orthogonal-waveform MIMO radar; knowledge-aided cognitive MIMO waveform design and algorithm; MIMO detection-communication integrated waveform design and algorithm; MIMO radar parameter estimation; MIMO radar target detection; and MIMO radar resource management and scheduling. Finally, the paper discusses the clutter suppression and Space-Time Adaptive Processing (STAP) of MIMO radar in airborne applications, the signal processing of MIMO radar in imaging, and the signal processing of chirp millimeter-wave (mmWave) MIMO radar based on time division multi-waveform diversity.

In view of the problems posed by low pozzolanic activity and large water requirement of normal consistency in the direct light calcinating of electronic fluorine-containing sludge as cement admixture, this paper uses coal gangue as a supplementary silicon and aluminum source of electronic fluorine-containing sludge to mix electronic fluorine-containing sludge and coal gangue and then to prepare cement admixture by light calcinating. This paper studied the effect of cement admixture prepared by light calcinating electronic fluorine-containing mixed with sludge coal gangue on cement properties through strength activity index, mechanical properties of cement, water requirement of normal consistency, setting time, particle size, X-ray diffraction and scanning electron microscopy. The results show that compared with direct light calcinating of electronic fluorine-containing sludge to prepare cement admixture, light calcinating of electronic fluorine-containing sludge mixed with coal gangue can improve the particle gradation of cement and reduce the water requirement of normal consistency of cement. It can significantly improve the activity of cement admixture and the strength of ordinary portland cement. Significantly extending the initial setting time and shorten the final setting time of cement.

The areas affected by the L1 transfer to L2, such as phonotactics and stress, appear to have different degrees of erasability through training and practice. This paper attempts a theoretical analysis to account for empirical observations of L1 transfer in diphthong-coda coalescence and in sentence stress for Chinese learners of English in an American accent training course. Using the framework and tableau method of Optimality Theory (Prince and Smolensky 1993), the phonological paradigm that views languages’ differences as symptomatic of differences in rankings of a set of universal violable constraints, this paper posits the underlying ranking at work in (a) the segmental case where [aŋ] is the observed output for /aʊn/; (b) the suprasegmental case where no stress contrast is observed for a pair of phonologically similar sentences with contrastive stress. It is argued that, in the segmental case, the coalescence of the second vowel of a diphthong with an alveolar nasal coda results from the high ranking of markedness constraints, including Complex Syllable; and in the suprasegmental case, sentence stress is greatly affected by changes in the ranking of the constraint culminativity. Aside from shedding light on the understudied issue of diphthong-coda coalescence, this research also contributes to the discussion of the comparative erasability of L1 transfer for the two areas and demonstrates how a deduction-based theoretical method may actually have practical implications for guiding the design of L2 teaching methodology of English pronunciation as well as for promoting native English speakers’ clearer understanding of Chinese learners of English on the global stage.