Small-scale farming accounts for 78% of total agricultural production in Kenya and contributes to 23.5% of the country’s GDP. Their crop production activities are mostly rainfed subsistence with any surplus being sol...Small-scale farming accounts for 78% of total agricultural production in Kenya and contributes to 23.5% of the country’s GDP. Their crop production activities are mostly rainfed subsistence with any surplus being sold to bring in some income. Timely decisions on farm practices such as farm preparation and planting are critical determinants of the seasonal outcomes. In Kenya, most small-scale farmers have no reliable source of information that would help them make timely and accurate decisions. County governments have extension officers who are mandated with giving farmers advisory services to farmers but they are not able to reach most farmers due to facilitation constraints. The mode and format of sharing information is also critical since it’s important to ensure that it’s timely, well-understood and usable. This study sought to assess access to geospatial derived and other crop production information by farmers in four selected counties of Kenya. Specific objectives were to determine the profile of small-scale farmers in terms of age, education and farm size;to determine the type of information that is made available to them by County and Sub-County extension officers including the format and mode of provision;and to determine if the information provided was useful in terms of accuracy, timeliness and adequacy. The results indicated that over 80% of the farmers were over 35 years of age and over 56% were male. Majority had attained primary education (34%) or secondary education (29%) and most farmers in all the counties grew maize (71%). Notably, fellow farmers were a source of information (71%) with the frequency of sharing information being mostly seasonal (37%) and when information was available (43%). Over 66% of interviewed farmers indicating that they faced challenges while using provided information. The results from the study are insightful and helpful in determining effective ways of providing farmers with useful information to ensure maximum benefits.展开更多
Human pluripotent stem cells(hPSCs), including human embryonic stem cells and human induced pluripotent stem cells, are promising sources for hematopoietic cells due to their unlimited growth capacity and the pluripot...Human pluripotent stem cells(hPSCs), including human embryonic stem cells and human induced pluripotent stem cells, are promising sources for hematopoietic cells due to their unlimited growth capacity and the pluripotency. Dendritic cells(DCs), the unique immune cells in the hematopoietic system, can be loaded with tumor specific antigen and used as vaccine for cancer immunotherapy. While autologous DCs from peripheral blood are limited in cell number, hPSC-derived DCs provide a novel alternative cell source which has the potential for large scale production. This review summarizes recent advances in differentiating hPSCs to DCs through the intermediate stage of hematopoietic stem cells. Step-wise growth factor induction has been used to derive DCs from hPSCs either in suspension cultureof embryoid bodies(EBs) or in co-culture with stromal cells. To fulfill the clinical potential of the DCs derived from hPSCs, the bioprocess needs to be scaled up to produce a large number of cells economically under tight quality control. This requires the development of novel bioreactor systems combining guided EB-based differentiation with engineered culture environment. Hence, recent progress in using bioreactors for hPSC lineage-specific differentiation is reviewed. In particular, the potential scale up strategies for the multistage DC differentiation and the effect of shear stress on hPSC differentiation in bioreactors are discussed in detail.展开更多
In order to ensure overall optimization of the underground metal mine production scale, multidisciplinary design optimization model of production scale which covers the subsystem objective function of income of produc...In order to ensure overall optimization of the underground metal mine production scale, multidisciplinary design optimization model of production scale which covers the subsystem objective function of income of production, safety and environmental impact in the underground metal mine was established by using multidisciplinary design optimization method. The coupling effects from various disciplines were fully considered, and adaptive mutative scale chaos immunization optimization algorithm was adopted to solve multidisciplinary design optimization model of underground metal mine production scale. Practical results show that multidisciplinary design optimization on production scale of an underground lead and zinc mine reflect the actual operating conditions more realistically, the production scale is about 1.25 Mt/a (Lead and zinc metal content of 160 000 t/a), the economic life is approximately 14 a, corresponding coefficient of production profits can be increased to 15.13%, safety factor can be increased to 5.4% and environmental impact coefficient can be reduced by 9.52%.展开更多
The enlarged production scale of underground non-ferrous metal mines is affected by many uncertain factors difficult to describe mathematically with any level of accuracy.The problem can be solved by a synthesis of ar...The enlarged production scale of underground non-ferrous metal mines is affected by many uncertain factors difficult to describe mathematically with any level of accuracy.The problem can be solved by a synthesis of artificial intelligence.Based on the analysis of the major factors affecting the scale of enlarged production,we first interpreted in detail the design principles and structure of the intelligent system.Secondly,we introduced an ANN subsystem.In order to ensure technological and scale efficien- cies of the training samples for ANN,we filtrated the samples with a DEA method.Finally,we trained the intelligent system,which was proved to be very efficient.展开更多
The moderate scale family farm is the future agricultural business entity in China,and the scale of family farm is a key factor affecting its development.With Guigang City in Guangxi as a point for the study,from the ...The moderate scale family farm is the future agricultural business entity in China,and the scale of family farm is a key factor affecting its development.With Guigang City in Guangxi as a point for the study,from the perspective of maximizing income of rural households,this paper uses production function model to calculate the moderate scale of food-production-based family farm at 5.7 ha,and makes policy recommendations.展开更多
The tobacco growers with the growing area of greater than or equal to 100 mu,have become an important subject of tobacco production in Weng'an County of Guizhou Province. Regulating and developing the production a...The tobacco growers with the growing area of greater than or equal to 100 mu,have become an important subject of tobacco production in Weng'an County of Guizhou Province. Regulating and developing the production and business activities of large-scale tobacco growers, plays an important role in stabilizing tobacco production,reducing costs and increasing efficiency in Weng'an County. Through the field survey of large-scale growers' production activities,this article analyzes the input and output levels,and explores the key factors influencing benefit, in order to provide a basis for further regulating the tobacco growing practices and improving the flue-cured tobacco production benefit.展开更多
Small-scale farmer is defined by the domestic and foreign experts and scholars.They point out that since the fragmentation of production and the diseconomy of scale in small-scale farmer is inconsistent with the chara...Small-scale farmer is defined by the domestic and foreign experts and scholars.They point out that since the fragmentation of production and the diseconomy of scale in small-scale farmer is inconsistent with the characteristics of scale and technology of modern agricultural production,it is necessary to eliminate the adverse effects of existing mode in order to provide theoretical references for the relevant researches.Citrus industry in Shimen County,Hunan Province,China is introduced from the aspects of natural geographical condition and socio-economic benefit.Impact of small-scale production mode on citrus production in Shimen County is discussed.Firstly,blindness of small-scale production is the main reason leading to overproduction of citrus.Secondly,small-scale production mode has limitation on the acceptance of new technologies,restricts the operation of geographical trademark,and constraints the enthusiasm of enterprises in entering the agricultural field.Finally,suggestions are put forward,such as encouraging the circulation of rural land,improving the organization degree of farmers,changing the work function of grass-roots government and perfecting the agricultural financial credit system.展开更多
Ecuador potato crop is family based production system. Potato production has two roles in their economy, the first is providing food for their families and the second is a source of income for the household. However s...Ecuador potato crop is family based production system. Potato production has two roles in their economy, the first is providing food for their families and the second is a source of income for the household. However small scale farmers have limited access to local markets and most of the sales are through intermediates’ who purchase directly in the field at the lowest price possible. Potato production challenges for the small-scale farmers are among others availability of quality potato seed, direct sales, purchase of agrochemical inputs to maintain their crops and lack of education. In 2021, only 4% of potato farmers used certified seed. Potato yield is still low around 16.1 t·ha<sup>-1</sup>, in the last 10 years the total potato cultivated area was reduced by at least 50%. The farmers produce “Bokashi” and other organic fertilizer and these are effective to improve soil fertility and plant health. Homemade bio-pesticides reduce agrochemical pesticides. The Decision Support System (DSS) is a handheld device to control late blight, minimizes fungicide applications and improve fungicide rotation. In 2018 Candidatus Liberibacter solanacearum (Lso), the causal agent of zebra chip, and its vector, the potato psyllid Bactericera cockerelli, together created havoc for farmers and researchers. Promotion of early potato varieties INIAP—Libertad is an alternative to lower the impact of this newest pest.展开更多
To investigate the correlation between structure characteristics and wear resistance of CO2 corrosion product scales at high temperature and high pressure, an autoclave was used to prepare CO2 corrosion product scales...To investigate the correlation between structure characteristics and wear resistance of CO2 corrosion product scales at high temperature and high pressure, an autoclave was used to prepare CO2 corrosion product scales on N80 steel in carbon dioxide corrosion environment. The correlation between wear resistance of the scales and many other factors, such as temperature, pressure, morphology, structure, velocity of fluid medium, sand grain size, and so on, was comparatively analyzed by a self assembled wear device, and the scale morphologies before or after being worn were observed by scanning electron microscope (SEM). And then the surface grain size and thickness of scale were measured. The results showed that the cross-section of the corrosion scale was of a double-layer structure, the outer layer of which was composed of regular crystals, whereas the inner layer was a thin scale of fine grains. The outer grain size and thickness of scale varied with temperature, and the initial wear loss was consistent with the surface grain size; at the same time, the total wear loss corresponded to the thickness of scale. Compared to wear resist- ance in different depths of the scale, it was found that the structure of scale was a double-layer structure in cross-section, and the wear resistance of inner layer was better than that of the outer layer; the closer the scale to the matrix, the greater was the wear resistance of scale; and the larger the size or the higher the rotary speed of solid grain in multiphase flowing medium, the more was the wear loss of scale.展开更多
China's hog production is undergoing a great transformation due to the soaring demand and changing raising system. Regarding the essential role of pork in Chinese diet, a systematic analysis on the productivity and e...China's hog production is undergoing a great transformation due to the soaring demand and changing raising system. Regarding the essential role of pork in Chinese diet, a systematic analysis on the productivity and efficiency of hog production can provide significant implications for policy makers. This paper investigates the productivity and efficiency of hog production and the determinants of technical efficiency in China using a household level panel data(2004–2010). A stochastic frontier translog production function with scaling property in inefficiency term is adopted for hog production analysis, and the determinants of technical efficiency are incorporated in a one-step estimation using maximum likelihood estimation. Our results show that the average technical efficiency of hog production in China is 0.5914. More importantly, we find that specialized farmers have higher technical efficiency than others, and technical efficiency in the eastern region is higher than that in Central and West China.展开更多
Agriculture is the foundation of the national economy.The periodicity of agricultural product output and prices,the asymmetry of information between buyers and sellers,and the inherent characteristics of small scale,h...Agriculture is the foundation of the national economy.The periodicity of agricultural product output and prices,the asymmetry of information between buyers and sellers,and the inherent characteristics of small scale,high cost,and low profit have caused slow sales,which greatly hurt the enthusiasm of farmers to develop production and endanger social stability.Constructing an informationized and commercialized trading platform and an information sharing platform through e-commerce and establishing related systems and supervision mechanisms will help to promote the rapid growth of agricultural product sales.Research has shown that in the field of agricultural circulation,e-commerce has a significant effect on increasing the scale of agricultural trade.展开更多
Using the DEA analysis method,on the basis of the national panel data from 2002 to 2014,this paper made a comparative analysis on the rice production performance before and after the implementation of direct grain sub...Using the DEA analysis method,on the basis of the national panel data from 2002 to 2014,this paper made a comparative analysis on the rice production performance before and after the implementation of direct grain subsidy policy,and made an empirical analysis on the relationship between the direct grain subsidy policy and the changes in the rice production performance. The results showed that the effect of the direct grain subsidy policy on promoting the rice production performance is declining year by year,largely because drop of scale efficiency. Besides,there are problems of serious redundancy in agricultural subsidy,unreasonable resource allocation,leading to low performance and resource waste of rice production.展开更多
Literatures about agricultural production efficiency are reviewed.Concept of DEA Method,as well as the definition methods of effective DEA and scale efficiency increase are introduced.According to the relevant statist...Literatures about agricultural production efficiency are reviewed.Concept of DEA Method,as well as the definition methods of effective DEA and scale efficiency increase are introduced.According to the relevant statistical data in the years 1997-2007 in Chongqing Municipality,efficiency of agricultural economy is calculated from the year 1997 to 2007 by DEA method and the scale efficiency is also analyzed by taking the total output of agriculture,forestry,animal husbandry and fishery industry as the output index.And the input index includes total workforce in agriculture,forestry,animal husbandry and fishery,the total sown area of crops,the total power of agricultural machinery,chemical fertilizer application,the draft animal,and the effective irrigation area.Result shows that Chongqing City became a municipality directly under the central government;its agricultural production efficiency is still low.And the sustainable development capacity of agricultural is weak in Chongqing,and the agricultural resources are not fully used.Based on this,related suggestions are put forward to improve the agricultural production efficiency of Chongqing,such as implementing an appropriate management scale of land,improving the organization degree of peasant households and the rate of industrialization management,enhancing the quality of the rural labor force,strengthening the agricultural science and technology input and extension,perfecting the construction of rural infrastructure,and improving the rate of resource utilization.展开更多
Kuwaiti oil production faces a growing challenge in the increasing quantities of produced water generated in the production of oil. The high water cut of the produced fluid from the wells and the high salinity of the ...Kuwaiti oil production faces a growing challenge in the increasing quantities of produced water generated in the production of oil. The high water cut of the produced fluid from the wells and the high salinity of the produced water lead to significant degradation of subsurface equipment, specifically the production tubing. Debris generated through the degradation of the inner part of the tubing becomes a constituent of the scaling that deposits in the tubing and blocks the flow of the production fluid, inducing higher maintenance costs. This paper looks at the characteristics of the scaling in regard to the produced water and outlines the economic impact of the produced water induced degradation of the tubing structure.展开更多
Studies on “strange” particle production have always occupied a very important space in the domain of Particle Physics. This was and is so, just because of some conjectures about specially abundant or excess product...Studies on “strange” particle production have always occupied a very important space in the domain of Particle Physics. This was and is so, just because of some conjectures about specially abundant or excess production of “strange” particles, at certain stages and under certain conditions arising out of what goes by the name of “Standard” model in Particle Physics. With the help of Hagedornian power laws we have attempted to understand and interpret here the nature of the pT-spectra for the strange particle production in a few high energy nuclear collisions, some interesting ratio-behaviors and the characteristics of the nuclear modification factors that are measured in laboratory experiments. After obtaining and analysing the final results we do not confront any peculiarities or oddities or extraneous excesses in the properties of the relevant observables with no left-over problems or puzzles. The model(s) used by us work(s) quite well for explaining the measured data.展开更多
Rice is one of the three major food crops in China.The change of its production cost is related to food security and farmers'income in China.This paper analyzes the changing trend of rice production cost in China ...Rice is one of the three major food crops in China.The change of its production cost is related to food security and farmers'income in China.This paper analyzes the changing trend of rice production cost in China from 2009 to 2019,analyzes the factors leading to the change from the aspects of land scale,labor force structure,agricultural science and technology level,etc.On this basis,this paper puts forward measures and suggestions to reduce rice production cost and improve farmers'income.展开更多
The interest of consumers in farming activities is evident and agricultural producers have responded to this increasing interest in a number of ways, including inviting visitors to farm operations through tourism or f...The interest of consumers in farming activities is evident and agricultural producers have responded to this increasing interest in a number of ways, including inviting visitors to farm operations through tourism or farm visits. Livestock industries, in particular, are interacting with the public in numerous ways, including via marketing channels for their products, interacting with community leaders and community members in regard to location siting and regulations, and inviting people onto their operations via agritourism. An improved understanding of who visits agricultural locations (particularly livestock operations) and consumers’ perceptions about livestock agriculture is needed in order to begin to understand the possible relationships between on-farm experiences and consumers’ perceptions. Thus, it is important to gain a deeper understanding in consumers’ interests, including their levels of concern for production process attributes, such as animal welfare, relative to product attributes like price and taste. This analysis investigates the demographics of consumers who have (and have not) visited various agritourism operations, studies differences in preferences for (or perceptions of) animal welfare relative to other pork attributes between consumers who have or have not visited a livestock operation, as well as amongst consumers with varying levels of involvement in household food production. Indeed the relationships explored are between having visited a livestock operation and the perceptions. This study found that 69% of participants had visited a livestock operation (pig farm, dairy farm, and/or horse farm) at some point. The majority of respondents agreed that agriculture was an important industry, yet, those who had visited livestock operations were more likely to note concerns about the impact of livestock operations on water quality in their county.展开更多
History of hybrid pepper seed production, the status of annually balanced production, and innovative techniques for the large-scale seed production in China are reviewed. Helped by the technological breakthroughs in t...History of hybrid pepper seed production, the status of annually balanced production, and innovative techniques for the large-scale seed production in China are reviewed. Helped by the technological breakthroughs in these fields, China has been the largest base for hybrid pepper seed production in the world.展开更多
This paper presents the results of analysis of the D? 1.0 fb-1 data on top-quark differential cross section measurements at the Fermilab Tevatron collider at √s= 1960 GeV in the framework of z-scaling approach. The f...This paper presents the results of analysis of the D? 1.0 fb-1 data on top-quark differential cross section measurements at the Fermilab Tevatron collider at √s= 1960 GeV in the framework of z-scaling approach. The flavor independence of scaling function Ψ(z)observed in pp and pp interactions over a wide collision energy range √s= 19-1960 GeV has been verified. This property of Ψ(z) was found for different hadrons – from π-mesons up to Υ particles. The flavor independence of Ψ(z) is used as indication on self-similarity of the top-quark production. A tendency to saturation of Ψ(z) at low z for top-quark production has been confirmed. Momentum fraction x1 of the incoming (anti)protons as a function of the scaled transverse momentum pT/m and masses of heavy mesons is studied. We anticipate that the data on low- and high-pT inclusive spectra of the top-quark production at the Tevatron and LHC energies could be of interest to verify self-similarity over a wide range of masses and different flavor content of produced particles.展开更多
文摘Small-scale farming accounts for 78% of total agricultural production in Kenya and contributes to 23.5% of the country’s GDP. Their crop production activities are mostly rainfed subsistence with any surplus being sold to bring in some income. Timely decisions on farm practices such as farm preparation and planting are critical determinants of the seasonal outcomes. In Kenya, most small-scale farmers have no reliable source of information that would help them make timely and accurate decisions. County governments have extension officers who are mandated with giving farmers advisory services to farmers but they are not able to reach most farmers due to facilitation constraints. The mode and format of sharing information is also critical since it’s important to ensure that it’s timely, well-understood and usable. This study sought to assess access to geospatial derived and other crop production information by farmers in four selected counties of Kenya. Specific objectives were to determine the profile of small-scale farmers in terms of age, education and farm size;to determine the type of information that is made available to them by County and Sub-County extension officers including the format and mode of provision;and to determine if the information provided was useful in terms of accuracy, timeliness and adequacy. The results indicated that over 80% of the farmers were over 35 years of age and over 56% were male. Majority had attained primary education (34%) or secondary education (29%) and most farmers in all the counties grew maize (71%). Notably, fellow farmers were a source of information (71%) with the frequency of sharing information being mostly seasonal (37%) and when information was available (43%). Over 66% of interviewed farmers indicating that they faced challenges while using provided information. The results from the study are insightful and helpful in determining effective ways of providing farmers with useful information to ensure maximum benefits.
基金Supported by In part by Florida State University start up fundFlorida State University Research Foundation GAP awardthe partial support from National Science Foundation,No.1342192
文摘Human pluripotent stem cells(hPSCs), including human embryonic stem cells and human induced pluripotent stem cells, are promising sources for hematopoietic cells due to their unlimited growth capacity and the pluripotency. Dendritic cells(DCs), the unique immune cells in the hematopoietic system, can be loaded with tumor specific antigen and used as vaccine for cancer immunotherapy. While autologous DCs from peripheral blood are limited in cell number, hPSC-derived DCs provide a novel alternative cell source which has the potential for large scale production. This review summarizes recent advances in differentiating hPSCs to DCs through the intermediate stage of hematopoietic stem cells. Step-wise growth factor induction has been used to derive DCs from hPSCs either in suspension cultureof embryoid bodies(EBs) or in co-culture with stromal cells. To fulfill the clinical potential of the DCs derived from hPSCs, the bioprocess needs to be scaled up to produce a large number of cells economically under tight quality control. This requires the development of novel bioreactor systems combining guided EB-based differentiation with engineered culture environment. Hence, recent progress in using bioreactors for hPSC lineage-specific differentiation is reviewed. In particular, the potential scale up strategies for the multistage DC differentiation and the effect of shear stress on hPSC differentiation in bioreactors are discussed in detail.
基金Project(2012BAK09B02-05) supported by the National "Twelfth Five-year" Science & Technology Support Plan of China
文摘In order to ensure overall optimization of the underground metal mine production scale, multidisciplinary design optimization model of production scale which covers the subsystem objective function of income of production, safety and environmental impact in the underground metal mine was established by using multidisciplinary design optimization method. The coupling effects from various disciplines were fully considered, and adaptive mutative scale chaos immunization optimization algorithm was adopted to solve multidisciplinary design optimization model of underground metal mine production scale. Practical results show that multidisciplinary design optimization on production scale of an underground lead and zinc mine reflect the actual operating conditions more realistically, the production scale is about 1.25 Mt/a (Lead and zinc metal content of 160 000 t/a), the economic life is approximately 14 a, corresponding coefficient of production profits can be increased to 15.13%, safety factor can be increased to 5.4% and environmental impact coefficient can be reduced by 9.52%.
基金Project 50374005 supported by the National Natural Science Foundation of China
文摘The enlarged production scale of underground non-ferrous metal mines is affected by many uncertain factors difficult to describe mathematically with any level of accuracy.The problem can be solved by a synthesis of artificial intelligence.Based on the analysis of the major factors affecting the scale of enlarged production,we first interpreted in detail the design principles and structure of the intelligent system.Secondly,we introduced an ANN subsystem.In order to ensure technological and scale efficien- cies of the training samples for ANN,we filtrated the samples with a DEA method.Finally,we trained the intelligent system,which was proved to be very efficient.
基金Supported by Scientific Research Project of Guangxi Universities in 2015
文摘The moderate scale family farm is the future agricultural business entity in China,and the scale of family farm is a key factor affecting its development.With Guigang City in Guangxi as a point for the study,from the perspective of maximizing income of rural households,this paper uses production function model to calculate the moderate scale of food-production-based family farm at 5.7 ha,and makes policy recommendations.
文摘The tobacco growers with the growing area of greater than or equal to 100 mu,have become an important subject of tobacco production in Weng'an County of Guizhou Province. Regulating and developing the production and business activities of large-scale tobacco growers, plays an important role in stabilizing tobacco production,reducing costs and increasing efficiency in Weng'an County. Through the field survey of large-scale growers' production activities,this article analyzes the input and output levels,and explores the key factors influencing benefit, in order to provide a basis for further regulating the tobacco growing practices and improving the flue-cured tobacco production benefit.
文摘Small-scale farmer is defined by the domestic and foreign experts and scholars.They point out that since the fragmentation of production and the diseconomy of scale in small-scale farmer is inconsistent with the characteristics of scale and technology of modern agricultural production,it is necessary to eliminate the adverse effects of existing mode in order to provide theoretical references for the relevant researches.Citrus industry in Shimen County,Hunan Province,China is introduced from the aspects of natural geographical condition and socio-economic benefit.Impact of small-scale production mode on citrus production in Shimen County is discussed.Firstly,blindness of small-scale production is the main reason leading to overproduction of citrus.Secondly,small-scale production mode has limitation on the acceptance of new technologies,restricts the operation of geographical trademark,and constraints the enthusiasm of enterprises in entering the agricultural field.Finally,suggestions are put forward,such as encouraging the circulation of rural land,improving the organization degree of farmers,changing the work function of grass-roots government and perfecting the agricultural financial credit system.
文摘Ecuador potato crop is family based production system. Potato production has two roles in their economy, the first is providing food for their families and the second is a source of income for the household. However small scale farmers have limited access to local markets and most of the sales are through intermediates’ who purchase directly in the field at the lowest price possible. Potato production challenges for the small-scale farmers are among others availability of quality potato seed, direct sales, purchase of agrochemical inputs to maintain their crops and lack of education. In 2021, only 4% of potato farmers used certified seed. Potato yield is still low around 16.1 t·ha<sup>-1</sup>, in the last 10 years the total potato cultivated area was reduced by at least 50%. The farmers produce “Bokashi” and other organic fertilizer and these are effective to improve soil fertility and plant health. Homemade bio-pesticides reduce agrochemical pesticides. The Decision Support System (DSS) is a handheld device to control late blight, minimizes fungicide applications and improve fungicide rotation. In 2018 Candidatus Liberibacter solanacearum (Lso), the causal agent of zebra chip, and its vector, the potato psyllid Bactericera cockerelli, together created havoc for farmers and researchers. Promotion of early potato varieties INIAP—Libertad is an alternative to lower the impact of this newest pest.
基金Item Sponsored by National Natural Science Foundation of China (50231020) , National Basic Research Programof China(G1999065004) ,2001'Key Laboratory Opening Fund of Corrosion and Protection of Tabular Goods Research Center of ChinaNational Petroleum Corporation (ZYT-01070)
文摘To investigate the correlation between structure characteristics and wear resistance of CO2 corrosion product scales at high temperature and high pressure, an autoclave was used to prepare CO2 corrosion product scales on N80 steel in carbon dioxide corrosion environment. The correlation between wear resistance of the scales and many other factors, such as temperature, pressure, morphology, structure, velocity of fluid medium, sand grain size, and so on, was comparatively analyzed by a self assembled wear device, and the scale morphologies before or after being worn were observed by scanning electron microscope (SEM). And then the surface grain size and thickness of scale were measured. The results showed that the cross-section of the corrosion scale was of a double-layer structure, the outer layer of which was composed of regular crystals, whereas the inner layer was a thin scale of fine grains. The outer grain size and thickness of scale varied with temperature, and the initial wear loss was consistent with the surface grain size; at the same time, the total wear loss corresponded to the thickness of scale. Compared to wear resist- ance in different depths of the scale, it was found that the structure of scale was a double-layer structure in cross-section, and the wear resistance of inner layer was better than that of the outer layer; the closer the scale to the matrix, the greater was the wear resistance of scale; and the larger the size or the higher the rotary speed of solid grain in multiphase flowing medium, the more was the wear loss of scale.
基金sponsored by the National Natural Science Foundation of China(71473123,71333008)A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD),ChinaChina Center for Food Security Studies,Nanjing Agricultural University,China
文摘China's hog production is undergoing a great transformation due to the soaring demand and changing raising system. Regarding the essential role of pork in Chinese diet, a systematic analysis on the productivity and efficiency of hog production can provide significant implications for policy makers. This paper investigates the productivity and efficiency of hog production and the determinants of technical efficiency in China using a household level panel data(2004–2010). A stochastic frontier translog production function with scaling property in inefficiency term is adopted for hog production analysis, and the determinants of technical efficiency are incorporated in a one-step estimation using maximum likelihood estimation. Our results show that the average technical efficiency of hog production in China is 0.5914. More importantly, we find that specialized farmers have higher technical efficiency than others, and technical efficiency in the eastern region is higher than that in Central and West China.
基金Supported by Guangxi Young and Middle-aged University Teachers’Scientific Research Ability Enhancement Project(2017KY0644).
文摘Agriculture is the foundation of the national economy.The periodicity of agricultural product output and prices,the asymmetry of information between buyers and sellers,and the inherent characteristics of small scale,high cost,and low profit have caused slow sales,which greatly hurt the enthusiasm of farmers to develop production and endanger social stability.Constructing an informationized and commercialized trading platform and an information sharing platform through e-commerce and establishing related systems and supervision mechanisms will help to promote the rapid growth of agricultural product sales.Research has shown that in the field of agricultural circulation,e-commerce has a significant effect on increasing the scale of agricultural trade.
文摘Using the DEA analysis method,on the basis of the national panel data from 2002 to 2014,this paper made a comparative analysis on the rice production performance before and after the implementation of direct grain subsidy policy,and made an empirical analysis on the relationship between the direct grain subsidy policy and the changes in the rice production performance. The results showed that the effect of the direct grain subsidy policy on promoting the rice production performance is declining year by year,largely because drop of scale efficiency. Besides,there are problems of serious redundancy in agricultural subsidy,unreasonable resource allocation,leading to low performance and resource waste of rice production.
文摘Literatures about agricultural production efficiency are reviewed.Concept of DEA Method,as well as the definition methods of effective DEA and scale efficiency increase are introduced.According to the relevant statistical data in the years 1997-2007 in Chongqing Municipality,efficiency of agricultural economy is calculated from the year 1997 to 2007 by DEA method and the scale efficiency is also analyzed by taking the total output of agriculture,forestry,animal husbandry and fishery industry as the output index.And the input index includes total workforce in agriculture,forestry,animal husbandry and fishery,the total sown area of crops,the total power of agricultural machinery,chemical fertilizer application,the draft animal,and the effective irrigation area.Result shows that Chongqing City became a municipality directly under the central government;its agricultural production efficiency is still low.And the sustainable development capacity of agricultural is weak in Chongqing,and the agricultural resources are not fully used.Based on this,related suggestions are put forward to improve the agricultural production efficiency of Chongqing,such as implementing an appropriate management scale of land,improving the organization degree of peasant households and the rate of industrialization management,enhancing the quality of the rural labor force,strengthening the agricultural science and technology input and extension,perfecting the construction of rural infrastructure,and improving the rate of resource utilization.
文摘Kuwaiti oil production faces a growing challenge in the increasing quantities of produced water generated in the production of oil. The high water cut of the produced fluid from the wells and the high salinity of the produced water lead to significant degradation of subsurface equipment, specifically the production tubing. Debris generated through the degradation of the inner part of the tubing becomes a constituent of the scaling that deposits in the tubing and blocks the flow of the production fluid, inducing higher maintenance costs. This paper looks at the characteristics of the scaling in regard to the produced water and outlines the economic impact of the produced water induced degradation of the tubing structure.
文摘Studies on “strange” particle production have always occupied a very important space in the domain of Particle Physics. This was and is so, just because of some conjectures about specially abundant or excess production of “strange” particles, at certain stages and under certain conditions arising out of what goes by the name of “Standard” model in Particle Physics. With the help of Hagedornian power laws we have attempted to understand and interpret here the nature of the pT-spectra for the strange particle production in a few high energy nuclear collisions, some interesting ratio-behaviors and the characteristics of the nuclear modification factors that are measured in laboratory experiments. After obtaining and analysing the final results we do not confront any peculiarities or oddities or extraneous excesses in the properties of the relevant observables with no left-over problems or puzzles. The model(s) used by us work(s) quite well for explaining the measured data.
文摘Rice is one of the three major food crops in China.The change of its production cost is related to food security and farmers'income in China.This paper analyzes the changing trend of rice production cost in China from 2009 to 2019,analyzes the factors leading to the change from the aspects of land scale,labor force structure,agricultural science and technology level,etc.On this basis,this paper puts forward measures and suggestions to reduce rice production cost and improve farmers'income.
文摘The interest of consumers in farming activities is evident and agricultural producers have responded to this increasing interest in a number of ways, including inviting visitors to farm operations through tourism or farm visits. Livestock industries, in particular, are interacting with the public in numerous ways, including via marketing channels for their products, interacting with community leaders and community members in regard to location siting and regulations, and inviting people onto their operations via agritourism. An improved understanding of who visits agricultural locations (particularly livestock operations) and consumers’ perceptions about livestock agriculture is needed in order to begin to understand the possible relationships between on-farm experiences and consumers’ perceptions. Thus, it is important to gain a deeper understanding in consumers’ interests, including their levels of concern for production process attributes, such as animal welfare, relative to product attributes like price and taste. This analysis investigates the demographics of consumers who have (and have not) visited various agritourism operations, studies differences in preferences for (or perceptions of) animal welfare relative to other pork attributes between consumers who have or have not visited a livestock operation, as well as amongst consumers with varying levels of involvement in household food production. Indeed the relationships explored are between having visited a livestock operation and the perceptions. This study found that 69% of participants had visited a livestock operation (pig farm, dairy farm, and/or horse farm) at some point. The majority of respondents agreed that agriculture was an important industry, yet, those who had visited livestock operations were more likely to note concerns about the impact of livestock operations on water quality in their county.
文摘History of hybrid pepper seed production, the status of annually balanced production, and innovative techniques for the large-scale seed production in China are reviewed. Helped by the technological breakthroughs in these fields, China has been the largest base for hybrid pepper seed production in the world.
基金supported by the IRP AVOZ10480505by the Ministry of Education of the Czech Republic grants LA08002,LA08015.
文摘This paper presents the results of analysis of the D? 1.0 fb-1 data on top-quark differential cross section measurements at the Fermilab Tevatron collider at √s= 1960 GeV in the framework of z-scaling approach. The flavor independence of scaling function Ψ(z)observed in pp and pp interactions over a wide collision energy range √s= 19-1960 GeV has been verified. This property of Ψ(z) was found for different hadrons – from π-mesons up to Υ particles. The flavor independence of Ψ(z) is used as indication on self-similarity of the top-quark production. A tendency to saturation of Ψ(z) at low z for top-quark production has been confirmed. Momentum fraction x1 of the incoming (anti)protons as a function of the scaled transverse momentum pT/m and masses of heavy mesons is studied. We anticipate that the data on low- and high-pT inclusive spectra of the top-quark production at the Tevatron and LHC energies could be of interest to verify self-similarity over a wide range of masses and different flavor content of produced particles.