Understanding the mechanical properties of the lithologies is crucial to accurately determine the horizontal stress magnitude.To investigate the correlation between the rock mass properties and maximum horizontal stre...Understanding the mechanical properties of the lithologies is crucial to accurately determine the horizontal stress magnitude.To investigate the correlation between the rock mass properties and maximum horizontal stress,the three-dimensional(3D)stress tensors at 89 measuring points determined using an improved overcoring technique in nine mines in China were adopted,a newly defined characteristic parameter C_(ERP)was proposed as an indicator for evaluating the structural properties of rock masses,and a fuzzy relation matrix was established using the information distribution method.The results indicate that both the vertical stress and horizontal stress exhibit a good linear growth relationship with depth.There is no remarkable correlation between the elastic modulus,Poisson's ratio and depth,and the distribution of data points is scattered and messy.Moreover,there is no obvious relationship between the rock quality designation(RQD)and depth.The maximum horizontal stress σ_(H) is a function of rock properties,showing a certain linear relationship with the C_(ERP)at the same depth.In addition,the overall change trend of σ_(H) determined by the established fuzzy identification method is to increase with the increase of C_(ERP).The fuzzy identification method also demonstrates a relatively detailed local relationship betweenσ_H and C_(ERP),and the predicted curve rises in a fluctuating way,which is in accord well with the measured stress data.展开更多
Farmers' professional cooperatives develop in various forms,and with the continuous improvement of development level,social effects have gradually appear.Based on the specific situation of farmers' professiona...Farmers' professional cooperatives develop in various forms,and with the continuous improvement of development level,social effects have gradually appear.Based on the specific situation of farmers' professional cooperatives in Shangqiu City,this paper expounded the development status of farmers' professional cooperatives in Shangqiu City,analyzed and discussed various problems encountered in the development process of farmers' professional cooperatives,and put forward some countermeasures and suggestions,such as establishing and perfecting cooperative rules and regulations,financing from multiple channels,introducing technical talents in various ways,breaking the information asymmetry restriction by various means,and giving full play to government functions,aiming to further promote standardized,large-scale,healthy and sustainable development of farmers' professional cooperatives.展开更多
In this article,the relevant instruments and techniques for measuring solid precipitation and blowing snow are reviewed,with a focus on the in situ instrument measurements.Moreover,a literature review and specific obs...In this article,the relevant instruments and techniques for measuring solid precipitation and blowing snow are reviewed,with a focus on the in situ instrument measurements.Moreover,a literature review and specific observation activities for solid precipitation are provided,the working principles of several instruments are introduced,and the advantages and disadvantages,measurement performance,and specific application scenarios of the instruments are evaluated.Currently,there are numerous solid precipitation measurement instruments available,and the standardization and sustainability of these measurements also need to be considered.The purpose of the review is not to be exhaustive but to provide readers with information on the current status of the development of relevant technologies and the prospects for their application in the polar regions.展开更多
According to the"National Modern Facility Agriculture Construction Plan(2023-2030)released by the Ministry of Agriculture and Rural Affairs,the"Special Implementation Plan for Modern Facility Fisheries Const...According to the"National Modern Facility Agriculture Construction Plan(2023-2030)released by the Ministry of Agriculture and Rural Affairs,the"Special Implementation Plan for Modern Facility Fisheries Construction"emphasizes the development of circular aquaculture,active expansion of green aquaculture space in facility fisheries,multi-channel development of food sources,comprehensive improvement of the quality,efficiency,and competitiveness of facility fisheries,ensuring stable and safe supply of aquatic products,and better meeting people's needs for high-quality aquatic products and beautiful aquatic ecological environment.Since the implementation of the 14th Five Year Plan for fisheries,facility fisheries have made significant progress.In order to thoroughly implement General Secretary Xi Jinping's important discourse on new quality productivity,conduct in-depth research on the current situation and existing problems of the fishery industry,and put forward suggestions to meet the requirements of high-quality development of the fishery industry in the new era.Therefore,it is crucial to continue practicing the"revitalization of aquatic seed industry"and"big food concept",take multiple measures to"demand food from rivers,lakes,and seas",and expand aquaculture space.Through research,it has been found that research in the field of facility based fisheries is still in its developmental stage.Further exploration is needed on the current status,breeding models,and experimental demonstrations of land-based facility based fisheries,in order to provide a basis for fisheries regulatory authorities to formulate the"15th Five Year Plan"for facility based fisheries.展开更多
The research analyzed status quo of Chinese tea export, including export scale, exporting countries and regions, product structure, explored factors affecting tea export, and detailed international trade development o...The research analyzed status quo of Chinese tea export, including export scale, exporting countries and regions, product structure, explored factors affecting tea export, and detailed international trade development of Chinese teas. On basis of global politics and economic situations, the research proposed new thoughts and of global trades of Chinese teas with application of the Belt and Road Initiative strategy.展开更多
[Objective] The aim was to analyze nutrients distribution and proportion in soils of farmlands of Gonggar County in Tibet. [Method] According to survey of soils in Tibet, nutrients of farmlands in Gonggar County were ...[Objective] The aim was to analyze nutrients distribution and proportion in soils of farmlands of Gonggar County in Tibet. [Method] According to survey of soils in Tibet, nutrients of farmlands in Gonggar County were analyzed and the countermeasures were proposed to achieve sustainable development of nutrients in soils. [Result] In Gonggar County in Tibet, farmlands with insufficient and less organic matter occupy 58.38%; farmlands with moderate contents of total N occupy 47.71%; farmlands with insufficient and less alkali-hydrolyzable nitrogen represent 82.36%; the farmlands with moderate and rich total P take up 49.40% and 21.59% ; farmlands with insufficient and less rapidly available P represent 67.33%; farmlands with richer and rich total K occupy 76.14% ; farmlands with moderate and insufficient rapidly available K represent 72.21%. [Conclusion] Based on nutrients in soils of farmlands, the countermeasures for sustainable utilization of nutrients in farmlands are proposed, including increase of organic fertilizer, soil testing and formulated fertilization and adjustment of acid-base balance.展开更多
Biogas fertilizer is widely used in agricultural production,and it can be used in a variety of ways,including liquid spraying,root fertilization,presoaking and biological pesticides,etc.It can improve soil structure,i...Biogas fertilizer is widely used in agricultural production,and it can be used in a variety of ways,including liquid spraying,root fertilization,presoaking and biological pesticides,etc.It can improve soil structure,increase the content of soil organic matter and available nutrients,and increase crop yield.In addition,there are some problems in the utilization of biogas fertilizer.Some details that need to be paid attention to and can not be ignored should be further studied and discussed to achieve a final principle of harmonious,safe and efficient use,so as to ensure the benefit maximization of biogas fertilizer as an economic fertilizer source.Therefore,this paper summarizes the main ways and methods,existing problems and corresponding development measures concerning the application of biogas fertilizer in agriculture,in order to provide some reference for the utilization of biogas fertilizer in the field of agriculture and make it universal,safe and stable.展开更多
[Objective] The aim was to analyze the current status and control measures of ecological restoration in Karst rocky desertification area of Guizhou.[Method] The current status and existing problems of ecological resto...[Objective] The aim was to analyze the current status and control measures of ecological restoration in Karst rocky desertification area of Guizhou.[Method] The current status and existing problems of ecological restoration in Karst rocky desertification area of Guizhou were studied firstly,and main control measures were put forward according to existing problems.[Result] At present,Karst rocky desertification area in Guizhou has suitable ecological environment,obvious control results and rich control experience,and there exist many problems like ambiguous concept of ecological restoration,biased control emphasis,single control measure and serious water shortage due to lagging engineering construction.Control measures mainly include combining natural restoration with artificial tending to speed up ecological restoration,reinforcing the restoration and rebuilding of development and construction project to prevent the deterioration of regional ecological environment,speeding up the construction of environmental friendly energy infrastructures to decrease the damage of vegetation by human activities,increasing industrial structure adjustment and greatly developing green industry and improving the investment in technological innovation to promote the rapid development of ecological restoration.[Conclusion] The study could provide scientific references for the ecological restoration in other Karst rocky desertification area in Southwest China.展开更多
Metal-ion batteries(MIBs),including alkali metal-ion(Li^(+),Na^(+),and K^(3)),multi-valent metal-ion(Zn^(2+),Mg^(2+),and Al^(3+)),metal-air,and metal-sulfur batteries,play an indispensable role in electrochemical ener...Metal-ion batteries(MIBs),including alkali metal-ion(Li^(+),Na^(+),and K^(3)),multi-valent metal-ion(Zn^(2+),Mg^(2+),and Al^(3+)),metal-air,and metal-sulfur batteries,play an indispensable role in electrochemical energy storage.However,the performance of MIBs is significantly influenced by numerous variables,resulting in multi-dimensional and long-term challenges in the field of battery research and performance enhancement.Machine learning(ML),with its capability to solve intricate tasks and perform robust data processing,is now catalyzing a revolutionary transformation in the development of MIB materials and devices.In this review,we summarize the utilization of ML algorithms that have expedited research on MIBs over the past five years.We present an extensive overview of existing algorithms,elucidating their details,advantages,and limitations in various applications,which encompass electrode screening,material property prediction,electrolyte formulation design,electrode material characterization,manufacturing parameter optimization,and real-time battery status monitoring.Finally,we propose potential solutions and future directions for the application of ML in advancing MIB development.展开更多
This paper presents a new technique for measuring the bunch length of a high-energy electron beam at a bunch-by-bunch rate in storage rings.This technique uses the time–frequency-domain joint analysis of the bunch si...This paper presents a new technique for measuring the bunch length of a high-energy electron beam at a bunch-by-bunch rate in storage rings.This technique uses the time–frequency-domain joint analysis of the bunch signal to obtain bunch-by-bunch and turn-by-turn longitudinal parameters,such as bunch length and synchronous phase.The bunch signal is obtained using a button electrode with a bandwidth of several gigahertz.The data acquisition device was a high-speed digital oscilloscope with a sampling rate of more than 10 GS/s,and the single-shot sampling data buffer covered thousands of turns.The bunch-length and synchronous phase information were extracted via offline calculations using Python scripts.The calibration coefficient of the system was determined using a commercial streak camera.Moreover,this technique was tested on two different storage rings and successfully captured various longitudinal transient processes during the harmonic cavity debugging process at the Shanghai Synchrotron Radiation Facility(SSRF),and longitudinal instabilities were observed during the single-bunch accumulation process at Hefei Light Source(HLS).For Gaussian-distribution bunches,the uncertainty of the bunch phase obtained using this technique was better than 0.2 ps,and the bunch-length uncertainty was better than 1 ps.The dynamic range exceeded 10 ms.This technology is a powerful and versatile beam diagnostic tool that can be conveniently deployed in high-energy electron storage rings.展开更多
Objective This study aims to explore the complex relationship between social engagement and depressive symptoms among older adults in China,focusing particularly on the moderating role of marital status.Methods This s...Objective This study aims to explore the complex relationship between social engagement and depressive symptoms among older adults in China,focusing particularly on the moderating role of marital status.Methods This study used data from the latest Chinese Longitudinal Healthy Longevity Survey(CLHLS).The analysis used the latent class analysis to delineate personality clusters and hierarchical linear regression,supplemented by the PROCESS macro,to investigate the effects of social engagement and marital status on depressive symptoms.Results The analysis encompassed 7,789 respondents(mean age:82.53[s=11.20]years),with 54%female.The personality analysis categorized participants into four clusters,with the majority(77.60%)classified as Confident Idealists,who exhibited the lowest levels of depressive symptoms.Hierarchical linear regression analysis yielded several significant findings:Higher levels of social engagement were significantly associated with fewer depressive symptoms(t=-7.932,P<0.001,B=-0.463).Marital status was a significant factor;married individuals reported fewer depressive symptoms compared to their unmarried counterparts(t=-6.368,P<0.001,B=-0.750).There was a significant moderating effect of marital status on the relationship between social engagement and depressive symptoms(t=-2.092,P=0.037,B=-0.217).Conclusion This study demonstrates that,among Chinese older adults,both social engagement and marital status significantly influence depressive symptoms.Higher social engagement,particularly in other activities like doing household chores,gardening,reading newspapers or books,and playing cards or Mahjong,is associated with fewer depressive symptoms,especially among married individuals.展开更多
Objective Pertussis cases have increased markedly since 2018 in Guangxi.The aim of this study was to evaluate antibody levels and the infection status of pertussis in the resident population.Method A total of 10,215 s...Objective Pertussis cases have increased markedly since 2018 in Guangxi.The aim of this study was to evaluate antibody levels and the infection status of pertussis in the resident population.Method A total of 10,215 serum samples from residents were collected from August-November 2018 and tested for anti-pertussis IgG and toxin IgG using the enzyme-linked immunosorbent assay(ELISA).Results Of the collected samples,1,833(17.94%)tested positive for anti-pertussis IgG,with the median concentration of 16.06 IU/mL.Antibody level<10 IU/mL accounted for more than 60%in children under 4 years of age,but declined with age,whereas the percentages of the other three levels(10-40,40-50,and≥50 IU/mL)increased almost with age(P<0.001).Moreover,7,924 samples were selected for anti-pertussis toxin IgG,of which 653(8.24%)tested positive(≥40 IU/mL)with the median concentration of 5.89 IU/mL,and 204 participants(2.56%)had recent pertussis infection(≥100 IU/mL).Among the different age groups,the highest rates of positivity and recent infection were observed at 11-20 years of age,the lowest positivity rate at 5 years of age,and the lowest recent infection rate at 4 years of age(P<0.001,P=0.005,respectively).Conclusion The survey results showed that all age groups in Guangxi lacked immunity against pertussis,which was one of the main factors contributing to the resurgence of pertussis in 2018.In addition,the prevalence of pertussis is relatively high in Guangxi,and its incidence is seriously underestimated,especially in adolescents and adults.展开更多
This paper establishes a model that would allow China's oil and gas enterprises to scientifically evaluate and measure their low-carbon level and status. It considers various characteristics of China's oil and gas e...This paper establishes a model that would allow China's oil and gas enterprises to scientifically evaluate and measure their low-carbon level and status. It considers various characteristics of China's oil and gas enterprises and the implications of low-carbon development, and is based on an overall analysis of factors that influence the reduction of carbon emissions. In view of low-carbon economic theories and the general principles of an evaluation index system, a comprehensive system for measuring the low-carbon status of China's oil and gas enterprises has been developed. This measurement system is comprised of four main criteria (energy structure, energy utilization, carbon emissions and utilization, and low carbon management) as well as thirty indexes. By the Delphi method and the analytical hierarchy process (AHP), the weight of the rules hierarchy and indexes hierarchy were determined. The standardized indexes were then integrated using a linear weighted sum formula, and a comprehensive formula for index measurement was established. Taking into account the status of low- carbon development in the petroleum and petrochemical industry at home and abroad, an evaluation criterion is proposed comprising four levels: ideal low-carbon, economical low-carbon, medium-carbon and high-carbon, whose values were organized within the settings of [0, 1].展开更多
Clarifying China’s position in the global system is an important logical basis for developing national diplomacy.Although much research has been done on China’s development status,most studies have been based on cou...Clarifying China’s position in the global system is an important logical basis for developing national diplomacy.Although much research has been done on China’s development status,most studies have been based on country comparisons or institutional en-vironment.In today’s networked era in which the global economy,trade,personnel,and information are closely connected,studies on China’s global position and its status changes and influencing factors in multiple contact networks are still insufficient.In this study,from the perspective of diverse global contact networks,we constructed economic,cultural,and political influence indices to explore the changes and influencing factors on China’s status in the global system from 2005 to 2018.The results show that during the study period,China’s global influence in the fields of economic ties,cultural exchanges,and political contacts increased significantly,but its influ-ence in the fields of cultural exchanges and political contacts lagged far economic ties.The pattern of China’s economic influence on various economies around the world has shown a transformation from an‘upright pyramid’to an‘inverted pyramid’structure.The proportion of these economies in low-influence zones has decreased from more than 60%in 2005 to less than 20%in 2018.China’s cultural and political influence on various economies around the world has increased significantly;however,for the former,the percentage of high-influence areas is still less than 20%,whereas for the latter the percentage of these economies in medium-and high-influence areas is still less than 50%.Analyses such as a scatter plot matrix show that geographical proximity,economic globalization,close cooperation with developing countries,and a proactive and peaceful foreign policy are important factors in improving China’s status in the diverse global network system.展开更多
The vibration interference of the reference corner cube runs through the free flight process of the free-falling corner cube,which is superimposed on the whole laser interference fringes.Thus,it is necessary to solve ...The vibration interference of the reference corner cube runs through the free flight process of the free-falling corner cube,which is superimposed on the whole laser interference fringes.Thus,it is necessary to solve the interference fringes with the entire fringe to analyze the quantitative influence of vibration on gravity measurements.展开更多
This study aims to improve the accuracy and safety of steel plate thickness calibration.A differential noncontact thickness measurement calibration system based on laser displacement sensors was designed to address th...This study aims to improve the accuracy and safety of steel plate thickness calibration.A differential noncontact thickness measurement calibration system based on laser displacement sensors was designed to address the problems of low precision of traditional contact thickness gauges and radiation risks of radiation-based thickness gauges.First,the measurement method and measurement structure of the thickness calibration system were introduced.Then,the hardware circuit of the thickness system was established based on the STM32 core chip.Finally,the system software was designed to implement system control to filter algorithms and human-computer interaction.Experiments have proven the excellent performance of the differential noncontact thickness measurement calibration system based on laser displacement sensors,which not only considerably improves measurement accuracy but also effectively reduces safety risks during the measurement process.The system offers guiding significance and application value in the field of steel plate production and processing.展开更多
In recent years,with the support and promotion of relevant policies such as the Opinions on Promoting Study Tour for Primary and Secondary School Students jointly issued by the Ministry of Education and 11 other depar...In recent years,with the support and promotion of relevant policies such as the Opinions on Promoting Study Tour for Primary and Secondary School Students jointly issued by the Ministry of Education and 11 other departments,a wave of study tour has been sparked nationwide from individual pilot projects to gradual promotion.In this paper,students and teachers from grades 4 to 6 of L Primary School in Nanchang City,Jiangxi Province were selected as the survey objects.Combining the survey questionnaire,the current situation of conducting study tour in the primary school was sorted out and analyzed in depth from several aspects such as study tour cognition,study tour participation,study tour implementation,etc.Based on the survey results and relevant research,the current problems in conducting study tours in primary schools were summarized,and targeted improvement measures were proposed,in order to promote the healthy development of study tours in primary schools.展开更多
To study the microscopic structure,thermal and mechanical properties of sandstones under the influence of temperature,coal measure sandstones from Southwest China are adopted as the research object to carry out high-t...To study the microscopic structure,thermal and mechanical properties of sandstones under the influence of temperature,coal measure sandstones from Southwest China are adopted as the research object to carry out high-temperature tests at 25℃-1000℃.The microscopic images of sandstone after thermal treatment are obtained by means of polarizing microscopy and scanning electron microscopy(SEM).Based on thermogravimetric(TG)analysis and differential scanning calorimetric(DSC)analysis,the model function of coal measure sandstone is explored through thermal analysis kinetics(TAK)theory,and the kinetic parameters of thermal decomposition and the thermal decomposition reaction rate of rock are studied.Through the uniaxial compression experiments,the stress‒strain curves and strength characteristics of sandstone under the influence of temperature are obtained.The results show that the temperature has a significant effect on the microstructure,mineral composition and mechanical properties of sandstone.In particular,when the temperature exceeds 400℃,the thermal fracture phenomenon of rock is obvious,the activity of activated molecules is significantly enhanced,and the kinetic phenomenon of the thermal decomposition reaction of rock appears rapidly.The mechanical properties of rock are weakened under the influence of rock thermal fracture and mineral thermal decomposition.These research results can provide a reference for the analysis of surrounding rock stability and the control of disasters caused by thermal damage in areas such as underground coal gasification(UCG)channels and rock masses subjected to mine fires.展开更多
Knowledge about the seismic elastic modulus dispersion,and associated attenuation,in fluid-saturated rocks is essential for better interpretation of seismic observations taken as part of hydrocarbon identification and...Knowledge about the seismic elastic modulus dispersion,and associated attenuation,in fluid-saturated rocks is essential for better interpretation of seismic observations taken as part of hydrocarbon identification and time-lapse seismic surveillance of both conventional and unconventional reservoir and overburden performances.A Seismic Elastic Moduli Module has been developed,based on the forced-oscillations method,to experimentally investigate the frequency dependence of Young's modulus and Poisson's ratio,as well as the inferred attenuation,of cylindrical samples under different confining pressure conditions.Calibration with three standard samples showed that the measured elastic moduli were consistent with the published data,indicating that the new apparatus can operate reliably over a wide frequency range of f∈[1-2000,10^(6)]Hz.The Young's modulus and Poisson's ratio of the shale and the tight sandstone samples were measured under axial stress oscillations to assess the frequency-and pressure-dependent effects.Under dry condition,both samples appear to be nearly frequency independent,with weak pressure dependence for the shale and significant pressure dependence for the sandstone.In particular,it was found that the tight sandstone with complex pore microstructure exhibited apparent dispersion and attenuation under brine or glycerin saturation conditions,the levels of which were strongly influenced by the increased effective pressure.In addition,the measured Young's moduli results were compared with the theoretical predictions from a scaled poroelastic model with a reasonably good agreement,revealing that the combined fluid flow mechanisms at both mesoscopic and microscopic scales possibly responsible for the measured dispersion.展开更多
The retarding effect of protein retarder on phosphorus building gypsum(PBG)and desulfurization building gypsum(DBG)was investigated,and the results show that protein retarder for DBG can effectively prolong the settin...The retarding effect of protein retarder on phosphorus building gypsum(PBG)and desulfurization building gypsum(DBG)was investigated,and the results show that protein retarder for DBG can effectively prolong the setting time and displays a better retarding effect,but for PBG shows a poor retarding effect.Furthermore,the deterioration reason of the retarding effect of protein retarder on PBG was investigated by measuring the pH value and the retarder concentration of the liquid phase from vacuum filtration of PBG slurry at different hydration time,and the measure to improve the retarding effect of protein retarding on PBG was suggested.The pH value of PBG slurry(<5.0)is lower than that of DBG slurry(7.8-8.5).After hydration for 5 min,the concentration of retarder in liquid phase of DBG slurry gradually decreases,but in liquid phase of PBG slurry continually increases,which results in the worse retarding effect of protein retarder on PBG.The liquid phase pH value of PBG slurry can be adjusted higher by sodium silicate,which is beneficial to improvement in the retarding effect of the retarder.By adding 1.0%of sodium silicate,the initial setting time of PBG was efficiently prolonged from 17 to 210 min,but little effect on the absolute dry flexural strength was observed.展开更多
基金financially supported by the National Natural Science Foundation of China(No.52204084)the Open Research Fund of the State Key Laboratory of Coal Resources and safe Mining,CUMT,China(No.SKLCRSM 23KF004)+3 种基金the Interdisciplinary Research Project for Young Teachers of USTB(Fundamental Research Funds for the Central Universities),China(No.FRF-IDRY-GD22-002)the Fundamental Research Funds for the Central Universities and the Youth Teacher International Exchange and Growth Program,China(No.QNXM20220009)the National Key R&D Program of China(Nos.2022YFC2905600 and 2022 YFC3004601)the Science,Technology&Innovation Project of Xiongan New Area,China(No.2023XAGG0061)。
文摘Understanding the mechanical properties of the lithologies is crucial to accurately determine the horizontal stress magnitude.To investigate the correlation between the rock mass properties and maximum horizontal stress,the three-dimensional(3D)stress tensors at 89 measuring points determined using an improved overcoring technique in nine mines in China were adopted,a newly defined characteristic parameter C_(ERP)was proposed as an indicator for evaluating the structural properties of rock masses,and a fuzzy relation matrix was established using the information distribution method.The results indicate that both the vertical stress and horizontal stress exhibit a good linear growth relationship with depth.There is no remarkable correlation between the elastic modulus,Poisson's ratio and depth,and the distribution of data points is scattered and messy.Moreover,there is no obvious relationship between the rock quality designation(RQD)and depth.The maximum horizontal stress σ_(H) is a function of rock properties,showing a certain linear relationship with the C_(ERP)at the same depth.In addition,the overall change trend of σ_(H) determined by the established fuzzy identification method is to increase with the increase of C_(ERP).The fuzzy identification method also demonstrates a relatively detailed local relationship betweenσ_H and C_(ERP),and the predicted curve rises in a fluctuating way,which is in accord well with the measured stress data.
文摘Farmers' professional cooperatives develop in various forms,and with the continuous improvement of development level,social effects have gradually appear.Based on the specific situation of farmers' professional cooperatives in Shangqiu City,this paper expounded the development status of farmers' professional cooperatives in Shangqiu City,analyzed and discussed various problems encountered in the development process of farmers' professional cooperatives,and put forward some countermeasures and suggestions,such as establishing and perfecting cooperative rules and regulations,financing from multiple channels,introducing technical talents in various ways,breaking the information asymmetry restriction by various means,and giving full play to government functions,aiming to further promote standardized,large-scale,healthy and sustainable development of farmers' professional cooperatives.
基金supported by the National Key Research and Development Program of China(Grant no.2021YFC2802501).
文摘In this article,the relevant instruments and techniques for measuring solid precipitation and blowing snow are reviewed,with a focus on the in situ instrument measurements.Moreover,a literature review and specific observation activities for solid precipitation are provided,the working principles of several instruments are introduced,and the advantages and disadvantages,measurement performance,and specific application scenarios of the instruments are evaluated.Currently,there are numerous solid precipitation measurement instruments available,and the standardization and sustainability of these measurements also need to be considered.The purpose of the review is not to be exhaustive but to provide readers with information on the current status of the development of relevant technologies and the prospects for their application in the polar regions.
基金supported by the National Bulk Freshwater Fish Industry Technology System(CARS-45-33)Tianjin Freshwater Aquaculture Industry Technology System Innovation Team(ITTFRS20211000-005/002)+2 种基金Tianjin Science and Technology Plan Project(23YDTPJC00420)Central Guiding Local Science and Technology Development Fund(24ZYCGSN00250)Open Fund of Key Laboratory of Environmental Standards and Environmental Pollution of the Ministry of Education(202007,202105).
文摘According to the"National Modern Facility Agriculture Construction Plan(2023-2030)released by the Ministry of Agriculture and Rural Affairs,the"Special Implementation Plan for Modern Facility Fisheries Construction"emphasizes the development of circular aquaculture,active expansion of green aquaculture space in facility fisheries,multi-channel development of food sources,comprehensive improvement of the quality,efficiency,and competitiveness of facility fisheries,ensuring stable and safe supply of aquatic products,and better meeting people's needs for high-quality aquatic products and beautiful aquatic ecological environment.Since the implementation of the 14th Five Year Plan for fisheries,facility fisheries have made significant progress.In order to thoroughly implement General Secretary Xi Jinping's important discourse on new quality productivity,conduct in-depth research on the current situation and existing problems of the fishery industry,and put forward suggestions to meet the requirements of high-quality development of the fishery industry in the new era.Therefore,it is crucial to continue practicing the"revitalization of aquatic seed industry"and"big food concept",take multiple measures to"demand food from rivers,lakes,and seas",and expand aquaculture space.Through research,it has been found that research in the field of facility based fisheries is still in its developmental stage.Further exploration is needed on the current status,breeding models,and experimental demonstrations of land-based facility based fisheries,in order to provide a basis for fisheries regulatory authorities to formulate the"15th Five Year Plan"for facility based fisheries.
文摘The research analyzed status quo of Chinese tea export, including export scale, exporting countries and regions, product structure, explored factors affecting tea export, and detailed international trade development of Chinese teas. On basis of global politics and economic situations, the research proposed new thoughts and of global trades of Chinese teas with application of the Belt and Road Initiative strategy.
基金Supported by Fund from Science and Technology Department of Tibet Autonomous Region ([2009]162)~~
文摘[Objective] The aim was to analyze nutrients distribution and proportion in soils of farmlands of Gonggar County in Tibet. [Method] According to survey of soils in Tibet, nutrients of farmlands in Gonggar County were analyzed and the countermeasures were proposed to achieve sustainable development of nutrients in soils. [Result] In Gonggar County in Tibet, farmlands with insufficient and less organic matter occupy 58.38%; farmlands with moderate contents of total N occupy 47.71%; farmlands with insufficient and less alkali-hydrolyzable nitrogen represent 82.36%; the farmlands with moderate and rich total P take up 49.40% and 21.59% ; farmlands with insufficient and less rapidly available P represent 67.33%; farmlands with richer and rich total K occupy 76.14% ; farmlands with moderate and insufficient rapidly available K represent 72.21%. [Conclusion] Based on nutrients in soils of farmlands, the countermeasures for sustainable utilization of nutrients in farmlands are proposed, including increase of organic fertilizer, soil testing and formulated fertilization and adjustment of acid-base balance.
文摘Biogas fertilizer is widely used in agricultural production,and it can be used in a variety of ways,including liquid spraying,root fertilization,presoaking and biological pesticides,etc.It can improve soil structure,increase the content of soil organic matter and available nutrients,and increase crop yield.In addition,there are some problems in the utilization of biogas fertilizer.Some details that need to be paid attention to and can not be ignored should be further studied and discussed to achieve a final principle of harmonious,safe and efficient use,so as to ensure the benefit maximization of biogas fertilizer as an economic fertilizer source.Therefore,this paper summarizes the main ways and methods,existing problems and corresponding development measures concerning the application of biogas fertilizer in agriculture,in order to provide some reference for the utilization of biogas fertilizer in the field of agriculture and make it universal,safe and stable.
文摘[Objective] The aim was to analyze the current status and control measures of ecological restoration in Karst rocky desertification area of Guizhou.[Method] The current status and existing problems of ecological restoration in Karst rocky desertification area of Guizhou were studied firstly,and main control measures were put forward according to existing problems.[Result] At present,Karst rocky desertification area in Guizhou has suitable ecological environment,obvious control results and rich control experience,and there exist many problems like ambiguous concept of ecological restoration,biased control emphasis,single control measure and serious water shortage due to lagging engineering construction.Control measures mainly include combining natural restoration with artificial tending to speed up ecological restoration,reinforcing the restoration and rebuilding of development and construction project to prevent the deterioration of regional ecological environment,speeding up the construction of environmental friendly energy infrastructures to decrease the damage of vegetation by human activities,increasing industrial structure adjustment and greatly developing green industry and improving the investment in technological innovation to promote the rapid development of ecological restoration.[Conclusion] The study could provide scientific references for the ecological restoration in other Karst rocky desertification area in Southwest China.
基金supported by the National Natural Science Foundation of China(52203364,52188101,52020105010)the National Key R&D Program of China(2021YFB3800300,2022YFB3803400)+2 种基金the Strategic Priority Research Program of Chinese Academy of Science(XDA22010602)the China Postdoctoral Science Foundation(2022M713214)the China National Postdoctoral Program for Innovative Talents(BX2021321)。
文摘Metal-ion batteries(MIBs),including alkali metal-ion(Li^(+),Na^(+),and K^(3)),multi-valent metal-ion(Zn^(2+),Mg^(2+),and Al^(3+)),metal-air,and metal-sulfur batteries,play an indispensable role in electrochemical energy storage.However,the performance of MIBs is significantly influenced by numerous variables,resulting in multi-dimensional and long-term challenges in the field of battery research and performance enhancement.Machine learning(ML),with its capability to solve intricate tasks and perform robust data processing,is now catalyzing a revolutionary transformation in the development of MIB materials and devices.In this review,we summarize the utilization of ML algorithms that have expedited research on MIBs over the past five years.We present an extensive overview of existing algorithms,elucidating their details,advantages,and limitations in various applications,which encompass electrode screening,material property prediction,electrolyte formulation design,electrode material characterization,manufacturing parameter optimization,and real-time battery status monitoring.Finally,we propose potential solutions and future directions for the application of ML in advancing MIB development.
基金supported by the National Key R&D Program(No.2022YFA1602201)。
文摘This paper presents a new technique for measuring the bunch length of a high-energy electron beam at a bunch-by-bunch rate in storage rings.This technique uses the time–frequency-domain joint analysis of the bunch signal to obtain bunch-by-bunch and turn-by-turn longitudinal parameters,such as bunch length and synchronous phase.The bunch signal is obtained using a button electrode with a bandwidth of several gigahertz.The data acquisition device was a high-speed digital oscilloscope with a sampling rate of more than 10 GS/s,and the single-shot sampling data buffer covered thousands of turns.The bunch-length and synchronous phase information were extracted via offline calculations using Python scripts.The calibration coefficient of the system was determined using a commercial streak camera.Moreover,this technique was tested on two different storage rings and successfully captured various longitudinal transient processes during the harmonic cavity debugging process at the Shanghai Synchrotron Radiation Facility(SSRF),and longitudinal instabilities were observed during the single-bunch accumulation process at Hefei Light Source(HLS).For Gaussian-distribution bunches,the uncertainty of the bunch phase obtained using this technique was better than 0.2 ps,and the bunch-length uncertainty was better than 1 ps.The dynamic range exceeded 10 ms.This technology is a powerful and versatile beam diagnostic tool that can be conveniently deployed in high-energy electron storage rings.
基金supported by National Natural Science Foundation of China[72174183].
文摘Objective This study aims to explore the complex relationship between social engagement and depressive symptoms among older adults in China,focusing particularly on the moderating role of marital status.Methods This study used data from the latest Chinese Longitudinal Healthy Longevity Survey(CLHLS).The analysis used the latent class analysis to delineate personality clusters and hierarchical linear regression,supplemented by the PROCESS macro,to investigate the effects of social engagement and marital status on depressive symptoms.Results The analysis encompassed 7,789 respondents(mean age:82.53[s=11.20]years),with 54%female.The personality analysis categorized participants into four clusters,with the majority(77.60%)classified as Confident Idealists,who exhibited the lowest levels of depressive symptoms.Hierarchical linear regression analysis yielded several significant findings:Higher levels of social engagement were significantly associated with fewer depressive symptoms(t=-7.932,P<0.001,B=-0.463).Marital status was a significant factor;married individuals reported fewer depressive symptoms compared to their unmarried counterparts(t=-6.368,P<0.001,B=-0.750).There was a significant moderating effect of marital status on the relationship between social engagement and depressive symptoms(t=-2.092,P=0.037,B=-0.217).Conclusion This study demonstrates that,among Chinese older adults,both social engagement and marital status significantly influence depressive symptoms.Higher social engagement,particularly in other activities like doing household chores,gardening,reading newspapers or books,and playing cards or Mahjong,is associated with fewer depressive symptoms,especially among married individuals.
基金approved by the Ethics Committee of the Guangxi Zhuang Autonomous Region Center for Disease Control and Prevention(GXIRB 2018-0005),and the participants signed informed consent forms.
文摘Objective Pertussis cases have increased markedly since 2018 in Guangxi.The aim of this study was to evaluate antibody levels and the infection status of pertussis in the resident population.Method A total of 10,215 serum samples from residents were collected from August-November 2018 and tested for anti-pertussis IgG and toxin IgG using the enzyme-linked immunosorbent assay(ELISA).Results Of the collected samples,1,833(17.94%)tested positive for anti-pertussis IgG,with the median concentration of 16.06 IU/mL.Antibody level<10 IU/mL accounted for more than 60%in children under 4 years of age,but declined with age,whereas the percentages of the other three levels(10-40,40-50,and≥50 IU/mL)increased almost with age(P<0.001).Moreover,7,924 samples were selected for anti-pertussis toxin IgG,of which 653(8.24%)tested positive(≥40 IU/mL)with the median concentration of 5.89 IU/mL,and 204 participants(2.56%)had recent pertussis infection(≥100 IU/mL).Among the different age groups,the highest rates of positivity and recent infection were observed at 11-20 years of age,the lowest positivity rate at 5 years of age,and the lowest recent infection rate at 4 years of age(P<0.001,P=0.005,respectively).Conclusion The survey results showed that all age groups in Guangxi lacked immunity against pertussis,which was one of the main factors contributing to the resurgence of pertussis in 2018.In addition,the prevalence of pertussis is relatively high in Guangxi,and its incidence is seriously underestimated,especially in adolescents and adults.
基金financially supported by CNPC major Scientific and Technological Special Project (2011E-24)
文摘This paper establishes a model that would allow China's oil and gas enterprises to scientifically evaluate and measure their low-carbon level and status. It considers various characteristics of China's oil and gas enterprises and the implications of low-carbon development, and is based on an overall analysis of factors that influence the reduction of carbon emissions. In view of low-carbon economic theories and the general principles of an evaluation index system, a comprehensive system for measuring the low-carbon status of China's oil and gas enterprises has been developed. This measurement system is comprised of four main criteria (energy structure, energy utilization, carbon emissions and utilization, and low carbon management) as well as thirty indexes. By the Delphi method and the analytical hierarchy process (AHP), the weight of the rules hierarchy and indexes hierarchy were determined. The standardized indexes were then integrated using a linear weighted sum formula, and a comprehensive formula for index measurement was established. Taking into account the status of low- carbon development in the petroleum and petrochemical industry at home and abroad, an evaluation criterion is proposed comprising four levels: ideal low-carbon, economical low-carbon, medium-carbon and high-carbon, whose values were organized within the settings of [0, 1].
基金Under the auspices of National Natural Science Foundation of China(No.42201181,42171181)Fundamental Research Funds for the Central Universities(No.2412022QD002)The Medium and Long-term Major Training Foundation of Philosophy and Social Sciences of Northeast Normal University(No.22FR006)。
文摘Clarifying China’s position in the global system is an important logical basis for developing national diplomacy.Although much research has been done on China’s development status,most studies have been based on country comparisons or institutional en-vironment.In today’s networked era in which the global economy,trade,personnel,and information are closely connected,studies on China’s global position and its status changes and influencing factors in multiple contact networks are still insufficient.In this study,from the perspective of diverse global contact networks,we constructed economic,cultural,and political influence indices to explore the changes and influencing factors on China’s status in the global system from 2005 to 2018.The results show that during the study period,China’s global influence in the fields of economic ties,cultural exchanges,and political contacts increased significantly,but its influ-ence in the fields of cultural exchanges and political contacts lagged far economic ties.The pattern of China’s economic influence on various economies around the world has shown a transformation from an‘upright pyramid’to an‘inverted pyramid’structure.The proportion of these economies in low-influence zones has decreased from more than 60%in 2005 to less than 20%in 2018.China’s cultural and political influence on various economies around the world has increased significantly;however,for the former,the percentage of high-influence areas is still less than 20%,whereas for the latter the percentage of these economies in medium-and high-influence areas is still less than 50%.Analyses such as a scatter plot matrix show that geographical proximity,economic globalization,close cooperation with developing countries,and a proactive and peaceful foreign policy are important factors in improving China’s status in the diverse global network system.
基金funded by Hebei Key Laboratory of Seismic Disaster Instrument and Monitoring Technology(Grant No.FZ224201)National Key Research and Development Project(Grant No.2022YFC2204301)the Special Fund of the Institute of Earthquake Forecasting,China Earthquake Administration(Grant No.CEAIEF2022030105).
文摘The vibration interference of the reference corner cube runs through the free flight process of the free-falling corner cube,which is superimposed on the whole laser interference fringes.Thus,it is necessary to solve the interference fringes with the entire fringe to analyze the quantitative influence of vibration on gravity measurements.
文摘This study aims to improve the accuracy and safety of steel plate thickness calibration.A differential noncontact thickness measurement calibration system based on laser displacement sensors was designed to address the problems of low precision of traditional contact thickness gauges and radiation risks of radiation-based thickness gauges.First,the measurement method and measurement structure of the thickness calibration system were introduced.Then,the hardware circuit of the thickness system was established based on the STM32 core chip.Finally,the system software was designed to implement system control to filter algorithms and human-computer interaction.Experiments have proven the excellent performance of the differential noncontact thickness measurement calibration system based on laser displacement sensors,which not only considerably improves measurement accuracy but also effectively reduces safety risks during the measurement process.The system offers guiding significance and application value in the field of steel plate production and processing.
基金Supported by Research Project on Basic Education in Jiangxi Province(SZUNDZH2021-1136,SZUNDZH2020-1138).
文摘In recent years,with the support and promotion of relevant policies such as the Opinions on Promoting Study Tour for Primary and Secondary School Students jointly issued by the Ministry of Education and 11 other departments,a wave of study tour has been sparked nationwide from individual pilot projects to gradual promotion.In this paper,students and teachers from grades 4 to 6 of L Primary School in Nanchang City,Jiangxi Province were selected as the survey objects.Combining the survey questionnaire,the current situation of conducting study tour in the primary school was sorted out and analyzed in depth from several aspects such as study tour cognition,study tour participation,study tour implementation,etc.Based on the survey results and relevant research,the current problems in conducting study tours in primary schools were summarized,and targeted improvement measures were proposed,in order to promote the healthy development of study tours in primary schools.
基金supported by the Scientific Research Foundation of State Key Laboratory of Coal Mine Disaster Dynamics and Control(Grant No.2011DA105287-zd201804)Jiangxi Provincial Natural Science Foundation of China(Grant No.20232BAB214036).
文摘To study the microscopic structure,thermal and mechanical properties of sandstones under the influence of temperature,coal measure sandstones from Southwest China are adopted as the research object to carry out high-temperature tests at 25℃-1000℃.The microscopic images of sandstone after thermal treatment are obtained by means of polarizing microscopy and scanning electron microscopy(SEM).Based on thermogravimetric(TG)analysis and differential scanning calorimetric(DSC)analysis,the model function of coal measure sandstone is explored through thermal analysis kinetics(TAK)theory,and the kinetic parameters of thermal decomposition and the thermal decomposition reaction rate of rock are studied.Through the uniaxial compression experiments,the stress‒strain curves and strength characteristics of sandstone under the influence of temperature are obtained.The results show that the temperature has a significant effect on the microstructure,mineral composition and mechanical properties of sandstone.In particular,when the temperature exceeds 400℃,the thermal fracture phenomenon of rock is obvious,the activity of activated molecules is significantly enhanced,and the kinetic phenomenon of the thermal decomposition reaction of rock appears rapidly.The mechanical properties of rock are weakened under the influence of rock thermal fracture and mineral thermal decomposition.These research results can provide a reference for the analysis of surrounding rock stability and the control of disasters caused by thermal damage in areas such as underground coal gasification(UCG)channels and rock masses subjected to mine fires.
基金The authors would like to acknowledge financial support from NSFC Basic Research Program on Deep Petroleum Resource Accumulation and Key Engineering Technologies(U19B6003-04-03)National Natural Science Foundation of China(41930425)+2 种基金Beijing Natural Science Foundation(8222073),R&D Department of China National Petroleum Corporation(Investigations on fundamental experiments and advanced theoretical methods in geophysical prospecting applications,2022DQ0604-01)Scientific Research and Technology Development Project of PetroChina(2021DJ1206)National Key Research and Development Program of China(2018YFA0702504).
文摘Knowledge about the seismic elastic modulus dispersion,and associated attenuation,in fluid-saturated rocks is essential for better interpretation of seismic observations taken as part of hydrocarbon identification and time-lapse seismic surveillance of both conventional and unconventional reservoir and overburden performances.A Seismic Elastic Moduli Module has been developed,based on the forced-oscillations method,to experimentally investigate the frequency dependence of Young's modulus and Poisson's ratio,as well as the inferred attenuation,of cylindrical samples under different confining pressure conditions.Calibration with three standard samples showed that the measured elastic moduli were consistent with the published data,indicating that the new apparatus can operate reliably over a wide frequency range of f∈[1-2000,10^(6)]Hz.The Young's modulus and Poisson's ratio of the shale and the tight sandstone samples were measured under axial stress oscillations to assess the frequency-and pressure-dependent effects.Under dry condition,both samples appear to be nearly frequency independent,with weak pressure dependence for the shale and significant pressure dependence for the sandstone.In particular,it was found that the tight sandstone with complex pore microstructure exhibited apparent dispersion and attenuation under brine or glycerin saturation conditions,the levels of which were strongly influenced by the increased effective pressure.In addition,the measured Young's moduli results were compared with the theoretical predictions from a scaled poroelastic model with a reasonably good agreement,revealing that the combined fluid flow mechanisms at both mesoscopic and microscopic scales possibly responsible for the measured dispersion.
文摘The retarding effect of protein retarder on phosphorus building gypsum(PBG)and desulfurization building gypsum(DBG)was investigated,and the results show that protein retarder for DBG can effectively prolong the setting time and displays a better retarding effect,but for PBG shows a poor retarding effect.Furthermore,the deterioration reason of the retarding effect of protein retarder on PBG was investigated by measuring the pH value and the retarder concentration of the liquid phase from vacuum filtration of PBG slurry at different hydration time,and the measure to improve the retarding effect of protein retarding on PBG was suggested.The pH value of PBG slurry(<5.0)is lower than that of DBG slurry(7.8-8.5).After hydration for 5 min,the concentration of retarder in liquid phase of DBG slurry gradually decreases,but in liquid phase of PBG slurry continually increases,which results in the worse retarding effect of protein retarder on PBG.The liquid phase pH value of PBG slurry can be adjusted higher by sodium silicate,which is beneficial to improvement in the retarding effect of the retarder.By adding 1.0%of sodium silicate,the initial setting time of PBG was efficiently prolonged from 17 to 210 min,but little effect on the absolute dry flexural strength was observed.