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Master-slave wave farm systems based on energy filter with smoothed power output 被引量:1
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作者 Zuanhong Yan Xiao-Ping Zhang 《Global Energy Interconnection》 2018年第5期559-567,共9页
Wave energy is an important renewable energy source. Previous studies of wave energy conversion(WEC) have focused on the maximum power take-off(PTO) techniques of a single machine. However, there is a lack of research... Wave energy is an important renewable energy source. Previous studies of wave energy conversion(WEC) have focused on the maximum power take-off(PTO) techniques of a single machine. However, there is a lack of research on the energy and power quality of wave farm systems. Owing to the pulsating nature of ocean waves and popular PTO devices, the generated electrical power suffers from severe fluctuations. Existing solutions require extra energy storage and overrated power converters for wave power integration. In this study, we developed a master-slave wave farm system with rotor inertia energy storage; this system delivers self-smoothed power output to the grid and reduces the number of converters. Two control methods based on the moving average filter(MAF) and energy filter(EF) are proposed to smooth the output power of wave farms. RTDS simulations show that the proposed systems and control methods facilitate simple and smooth grid integration of wave energy. 展开更多
关键词 WAVE farm ENERGY storage POWER smoothing POWER QUALITY ENERGY QUALITY
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Characteristics of sub-synchronous oscillation in grid-connected wind farm system
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作者 Yan Gong Qi Huang +1 位作者 Dong-Sheng Cai Bamisile Olusola Olorunfemi 《Journal of Electronic Science and Technology》 EI CSCD 2023年第4期91-101,共11页
With the rapid development of wind power, wind turbines are accompanied by a large quantity of power electronic converters connected to the grid, causing changes in the characteristics of the power system and leading ... With the rapid development of wind power, wind turbines are accompanied by a large quantity of power electronic converters connected to the grid, causing changes in the characteristics of the power system and leading to increasingly serious sub-synchronous oscillation (SSO) problems, which urgently require the generalized classification and characterization of the emerging oscillation problems. This paper classifies and characterizes the emerging types of SSO caused by grid-connected wind turbines to address these issues. Finally, the impact of the typical system parameters changes on the oscillation pattern is analyzed in depth to provide effective support for the subsequent suppression and prevention of SSO. 展开更多
关键词 CHARACTERISTICS CLASSIFICATION Sub-synchronous oscillation(SSO) Typical system parameters Wind farm
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Technical efficiency of cocoa farms at varying elevation levels in Davao City, Philippines: implications to sustainable upland farming systems
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作者 Francis Levi A.DURANO Jon Marx SARMIENTO +1 位作者 Larry N.DIGAL Pedro A.ALVIOLA IV 《Journal of Mountain Science》 SCIE CSCD 2024年第1期33-48,共16页
Elevation is one of many components that influence agriculture, and this in turn affects the level of both inputs and outputs of farmers. This article focuses on the productivity and technical efficiency of 100 cocoa ... Elevation is one of many components that influence agriculture, and this in turn affects the level of both inputs and outputs of farmers. This article focuses on the productivity and technical efficiency of 100 cocoa farms using cross-sectional data from areas ranging from 190 to 1021 m above sea level which were classified as low, medium, and high elevation in Davao City, considered as the chocolate capital of the Philippines. Using stochastic frontier analysis, the results showed that the cost of inputs per ha and the number of cocoa trees per ha significantly increase yield. Farms at high elevations were less technically efficient, as this entails lower temperatures and increased rainfall, and cocoa farming in those areas and conditions can be more challenging, especially with changes in farming practices, terrain, and distance to markets. Other significant variables were age of cocoa farms, married farmers, and age of the farmers. Older farms may be more developed, farmers who are married benefit from their spouses being able to readily contribute as farm labor, and lastly, older farmers' inefficiency may likely stem from nonadaptation of newer farming practices. With an average technical efficiency of 0.61, 0.63, and 0.26 in low, medium, and high elevation areas, respectively, farmers therefore have an incentive to improve farm practices and consider topographical variations found in high elevation areas. Recommendations for the improvement of technical efficiency of cocoa farms are better connectivity to markets, enhancing farm practices, and continuation and improvement of government programs on cocoa with an added emphasis on research. For farmers in high elevation areas, mitigating solutions such as sustainable agriculture practices and ecolabelling are key to improving efficiency and minimizing the potential negative impact on upland farming systems. Moreover, such adaptation measures may also contribute to sustainability of cocoa farming in high elevation areas. 展开更多
关键词 Cocoa farms Cobb-Douglas production function ELEVATION Philippines Stochastic frontier analysis Technical efficiency
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Transient Stability Preventive Control of Wind Farm Connected Power System Considering the Uncertainty
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作者 Yuping Bian Xiu Wan Xiaoyu Zhou 《Energy Engineering》 EI 2024年第6期1637-1656,共20页
To address uncertainty as well as transient stability constraints simultaneously in the preventive control of windfarm systems, a novel three-stage optimization strategy is established in this paper. In the first stag... To address uncertainty as well as transient stability constraints simultaneously in the preventive control of windfarm systems, a novel three-stage optimization strategy is established in this paper. In the first stage, the probabilisticmulti-objective particle swarm optimization based on the point estimate method is employed to cope with thestochastic factors. The transient security region of the system is accurately ensured by the interior point methodin the second stage. Finally, the verification of the final optimal objectives and satisfied constraints are enforcedin the last stage. Furthermore, the proposed strategy is a general framework that can combine other optimizationalgorithms. The proposed methodology is tested on the modified WSCC 9-bus system and the New England 39-bussystem. The results verify the feasibility of the method. 展开更多
关键词 Transient preventive control chance-constrained programming multi-objective PSO TSCOPF wind farm
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Waste Management Systems among Smallholder Farmers in Masaka and Lyantonde Districts, Central Uganda 被引量:1
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作者 Kamoga Gerald Ssekyewa Charles 《Journal of Agricultural Chemistry and Environment》 2021年第3期314-326,共13页
With diversity in farming systems, crop residues, animal wastes and management practices are often not well managed, and most of it is left on the soil surface. This practice is common, especially among smallholder fa... With diversity in farming systems, crop residues, animal wastes and management practices are often not well managed, and most of it is left on the soil surface. This practice is common, especially among smallholder farmers (SHFs). There is no updated record of commonly used waste management practices. Our study focused on smallholder farmers in two farming systems in Masaka and Lyantonde Districts respectively, and with the objective to determine smallholder waste management practices in relation to farm waste components. Using a sample survey, quantitative data were collected from 120 SHFs representing 10.1% of the total SHF population in the Masaka while 120 SHFs provided data and represented 17.4% of the total SHF population in Lyantonde. Our result revealed that for animal waste, Goat slurry 20.4%, dominated the rest in Lyantonde, while in Masaka Pig slurry 23.6%, was dominant. For crop waste in Lyantonde, Bean trashes 12.9%, dominated, while in Masaka Banana leaves and peelings 11.1%, were dominant. In Lyantonde, common waste management practices were: Surface deposition 41.2%, Burning 18.4% Composting 17.3%, Burying 9.4%, Removal 10.9% and Recycling 2.8%. In Masaka, common practices were: Surface deposition 40.9%, Burning 18.6% Composting 13.2%, Burrying 12.3%, Removal 6.2% and Recycling 8.8%. Factors affecting choice of waste management practices by SHFs were: Age, purpose of waste product, season, quantity of the wastes, waste management policy awareness, farmer’s commitment and economic status of the farmer. Greenhouse gas emission for identified waste management practices across the two Districts shall be determined in our next study. 展开更多
关键词 farm system farm Waste Smallholder farmer Practice Waste Management
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Impact of introducing a herb pasture area into a New Zealand sheep and beef hill country farm system: a modeling analysis
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作者 Cécile DURANTON Cory MATTHEW 《Frontiers of Agricultural Science and Engineering》 2018年第1期87-97,共11页
New Zealand is well known for export of meat and dairy products from low cost pastoral systems. These farm systems are continually evolving for increased efficiency, in part through the use of metabolic energy modelin... New Zealand is well known for export of meat and dairy products from low cost pastoral systems. These farm systems are continually evolving for increased efficiency, in part through the use of metabolic energy modeling tools by farmers and farm consultants to explore alternative farm system configurations and identify new efficiencies. One recent innovation is the introduction of a herb pasture area, such as plantain. We used metabolic energy modeling to quantify seasonal feed flows in two successive years in a New Zealand hill country farm system, and to analyze the impact of the introduction of an area of plantain. Models employed were a self-built Microsoft Excel spreadsheet and a commercial New Zealand farm systems modeling package, FARMAX.Herbage production, animal performance and financial results for a base farm scenario created from the average of survey data for hill farms in the southern North Island, and the same farm with 10% and 20% of the area in plantain for the years 2010–2011 and 2011–2012 were modeled. The self-built model performed similarly to the commercial model. The system configuration of the base farm stockpiles surplus autumn feed for release to animals in winter and also incorporates flexibility that confers resilience to interannual weather variation through varying dates animals are purchased or sold. The introduction of an area of plantain was predicted to increase herbage production, animal performance and financial returns.The predicted benefit was higher for the year 2010–2011 where a drought occurred in summer than for the following year with higher summer rainfall. This demonstrates the profitability of introducing a plantain area to New Zealand hill farm systems, and suggests plantain will assist to mitigate adverse effects of warmer and drier summer conditions associated with current climate change trends. 展开更多
关键词 farm system configuration herb pasture metabolic energy budgeting PLANTAIN sheep and beef farming
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Analysis on Development Potential of Agricultural Resources of Farming System in Shandong Province 被引量:1
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作者 黄娟 徐德力 +1 位作者 白清俊 周勋波 《Agricultural Science & Technology》 CAS 2012年第2期401-404,共4页
Based on the characteristics of agricultural resources and social resources in Shandong Province, the approaches of developing farming system potential were discussed, which provide important references for sustainabl... Based on the characteristics of agricultural resources and social resources in Shandong Province, the approaches of developing farming system potential were discussed, which provide important references for sustainable development of modern farming system. 展开更多
关键词 Shandong Province farming system Agricultural resources Development potential
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Long Term Effects of Farming System on Soil Water Content and Dry Soil Layer in Deep Loess Profile of Loess Tableland in China 被引量:11
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作者 CHENG Li-ping LIU Wen-zhao 《Journal of Integrative Agriculture》 SCIE CAS CSCD 2014年第6期1382-1392,共11页
Soil water is strongly affected by land use/cover in the Loess Plateau in China. Water stored in thick loessal soils is one of the most important resources regulating vegetation growth. However, soil water in the deep... Soil water is strongly affected by land use/cover in the Loess Plateau in China. Water stored in thick loessal soils is one of the most important resources regulating vegetation growth. However, soil water in the deep loess proifle, which is critical for maintaining the function of the“soil water pool”is rarely studied because deep proifle soil samples are dififcult to collect. In this study, four experimental plots were established in 2005 to represent different farming systems on the Changwu Tableland:fallow land, fertilized cropland, unfertilized cropland, and continuous alfalfa. The soil water content in the 15-m-deep loess proifles was monitored continuously from 2007 to 2012 with the neutron probe technique. The results showed that temporal variations in soil water proifles differed among the four farming systems. Under fallow land, the soil water content increased gradually over time, ifrst in the surface layers and later in the deep soil layers. In contrast, the soil water content decreased gradually under continuous alfalfa. The distributions of soil water in deep soil layers under both fertilized and unfertilized cropland were relatively stable over time. Thus farming system signiifcantly affected soil water content. Seven years after the start of the experiment, the soil water contents in the 15-m-deep proifles averaged 23.4%under fallow land, 20.3%under fertilized cropland, 21.6%under unfertilized cropland, and 16.0%under continuous alfalfa. Compared to measurements at the start of the experiment, both fallow land and unfertilized cropland increased soil water storage in the 15-m loess proifles. In contrast, continuous alfalfa reduced soil water storage. Fertilized cropland has no signiifcant effect on soil water storage. These results suggest that deep soil water can be replenished under the fallow and unfertilized farming systems. Dry soil layers (i.e., those which have soil water content less than the stable ifeld water capacity) in the subsoil of the Changwu Tableland region can be classiifed as either temporary dry soil layers or persistent dry soil layers. Temporary dry soil layers, which typically form under annual crops, often disappear during wet years. Persistent dry soil layers generally develop under perennial vegetation. Even after removing the vegetation, persistent dry soil layers remain for several decades. This study provides information useful for the conservation and utilization of soil water resources in the Loess Tableland. 展开更多
关键词 farming system temporal variability soil water dried soil layer Loess Plateau
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Performance of a water hyacinth(Eichhornia crassipes)system in the treatment of wastewater from a duck farm and the effects of using water hyacinth as duck feed 被引量:27
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作者 LU Jianbo FU Zhihui YIN Zhaozheng 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2008年第5期513-519,共7页
Nowadays, intensive breeding of poultry and livestock of large scale has made the treatment of its waste and wastewater an urgent environmental issue, which motivated this study. A wetland of 688 mz was constructed on... Nowadays, intensive breeding of poultry and livestock of large scale has made the treatment of its waste and wastewater an urgent environmental issue, which motivated this study. A wetland of 688 mz was constructed on an egg duck farm, and water hyacinth (Eichhornia crassipes) was chosen as an aquatic plant for the wetland and used as food for duck production. The objectives of this study were to test the role of water hyacinth in purifying nutrient-rich wastewater and its effects on the ducks' feed intake, egg laying performance and egg quality. This paper shows that the constructed wetland removed as much as 64.44% of chemical oxygen demand (COD), 21.78% of total nitrogen (TN) and 23.02% of total phosphorus (TP). Both dissolved oxygen (DO) and the transparency of the wastewater were remarkably improved, with its transparency 2.5 times higher than that of the untreated wastewater. After the ducks were fed with water hyacinth, the average daily feed intake and the egg-laying ratio in the test group were 5.86% and 9.79% higher, respectively, than in the control group; the differences were both significant at the 0.01 probability level. The egg weight in the test group was 2.36% higher than in the control group (P 〈 0.05), but the feed conversion ratios were almost the same. The eggshell thickness and strength were among the egg qualities significantly increased in ducks fed with water hyacinth. We concluded that a water hyacinth system was effective for purifying wastewater from an intensive duck farm during the water hyacinth growing season, as harvested water hyacinth had an excellent performance as duck feed. We also discussed the limitations of the experiment. 展开更多
关键词 water hyacinth (Eichhornia crassipes) duck farm constructed wetland chemical oxygen demand (COD) treatment effect egg-laying ratio egg quality
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The Evolution of Organic Carbon in Chinese Mollisol Under Different Farming Systems: Validation and Prediction by Using Century Model 被引量:6
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作者 GAO Chong-sheng WANG Jian-guo ZHANG Xing-yi SUI Yue-yu 《Agricultural Sciences in China》 CAS CSCD 2008年第12期1490-1496,共7页
Soil organic carbon (SOC) is an important indicator of soil degradation process. In this study, the long-term SOC evolution in Chinese mollisol farmland was simulated and predicted by validating, analyzing, processi... Soil organic carbon (SOC) is an important indicator of soil degradation process. In this study, the long-term SOC evolution in Chinese mollisol farmland was simulated and predicted by validating, analyzing, processing and assorting concerning data, based on clarifying parameters of Century model need, combined with best use of recorded data of field management, observed data of long-term experiments, climate, soil, and biology, and achieved results from Hailun Agro-Ecological Experimental Station, Chinese Academy of Sciences. The results were showed as follows: Before reclamation, SOC content was around 58.00 g kg^-1, SOC content dropped quickly in early years, and then decreased slowly after reclamation. SOC content was around 34.00 g kg^-1 with a yearly average rate of 8.91‰ decrease before long-term experiments was established. After a long-term experiment, SOC would change under different farming systems. Shift farming system changed as follows: By 20-year model simulation, SOC content decreased from 34.03 to 30.19 g kg^-1, with a yearly average rate of 5.97‰; by 100-year model simulation, SOC content decreased to 24.31 g kg^-1, with a yearly average rate of 3.36‰. Organic farming system changed as follows: By 20-year model simulation, SOC content decreased slowly from 34.03 to 33.39 g kg^-1, with a yearly average rate of 0.95‰, 5‰ less than that of shift farming system; by 100-year model simulation, SOC content decreased to 32.21 g kg^-1, with a yearly average rate of 0.55‰. "Petroleum" farming system changed as follows: By 20-year model simulation, SOC content decreased from 34.03 to 32.88 g kg^-1, with a yearly average rate of 1.72‰, much more than that of organic farming system; by 100-year model simulation, SOC content decreased to 30.89 g kg^-1, with a yearly average rate of 0.96‰. Combined "petroleum"-organic farming system changed as follows: By 20-year model simulation, SOC content was increased slightly; by 100-year model simulation, SOC content increased from 34.03 to 34.41g kg^-1, with a yearly average rate of 0.11‰. The above results provided an optimal way for maintaining SOC in Chinese mollisol farmland: To increase, as much as possible within agro-ecosystem, soil organic matter returns such as crop stubble, crop litter, crop straw or stalk, and manure, besides applying chemical nitrogen and phosphorous, which increased system productivity and maintained SOC content as well. Also, the results provided a valuable methodology both for a study of CO2 sequestration capacity and for a target fertility determination in Chinese mollisol. 展开更多
关键词 Century model Chinese mollisol farmland soil organic carbon various farming systems PREDICTION
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The Effect of Land Degradation on Farm Size Dynamics and Crop-Livestock Farming System in Ethiopia: A Review 被引量:3
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作者 Assemu Tesfa Shigdaf Mekuriaw 《Open Journal of Soil Science》 2014年第1期1-5,共5页
Ethiopia is among the poorest countries in which poverty, land and resource degradation appear to feed off each other. The irony is that Ethiopia is a country with high biodiversity and distinctive ecosystems and the ... Ethiopia is among the poorest countries in which poverty, land and resource degradation appear to feed off each other. The irony is that Ethiopia is a country with high biodiversity and distinctive ecosystems and the natural resource base is critical to the economy and the livelihood of a high percentage of the population. Being the owner of varying agro ecology, the country’s agricultural production system had practiced for decades with a maximum potential. However, because of the presence of interrelated problems, the productivity had not sustained as its potential. From the interrelated problems, land degradation takes the first and challengeable problem in many countries. Land degradation refers to a temporary or permanent decline in the productive capacity of the land, or its potential for environmental management as a result;the long-term biological and environmental potential of the land has been compromised. Land degradation in the Ethiopian highlands (i.e. areas above 1500 m.a.s.l.) has been a concern for many years and is a great threat for the future that requires great effort and resources to ameliorate. It had adverse effect on lowering of livestock production by shrinking grazing land, the fertile soil types were washed and the grazing land was dominantly covered by unpalatable pastures and grasses which had low nutritive value and fertility for crop-livestock production system. In other cases, degradation induces farmers to convert land to lower-value uses;for instance, cropland converted to grazing land, or grazing lands converted to shrubs or forests. Equitable and secure access to land is a critical factor for the rural poor, especially livestock owners, who depend on agriculture and animal-related activities for their livelihood. Having secure access to land for agriculture and pastoral activities reduces their vulnerability and enhances their opportunities to invest in land for agriculture and livestock activities. Historical patterns of feudal ownership of land followed by government ownership and despite policy change uncertain status of land ownership. These land distribution and ownership patterns coupled with continuous fragmentations and degradation disrupt the balance between crop, livestock, and forest production. These things nowadays enforce Ethiopian farmers to put more land into crop production than working on livestock sector. Livelihoods are complex, dependent on animal and crop production based on land and water resources, with emerging market opportunities. And from year to year, the size of farms is getting minimized because of land degradation and segmentations, and these make a change in farm size dynamics and farming shift. Currently, there is a great scenario towards the land policy pattern and agricultural production system, which is the backbone of the country’s economy. Therefore, the aim of this paper is to review the effect of land degradation on farm size dynamics and crop-livestock production since the impact of these things is not well measured. 展开更多
关键词 Crop-Livestock farmING system farmERS farm Size DYNAMICS Land Degradation
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Study of Digital Management System of Milking Process on Large-Sized Dairy Farm 被引量:3
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作者 XIONG Ben-hai LUO Qing-yao Lǔ Jian-qiang YANG Liang 《Agricultural Sciences in China》 CAS CSCD 2008年第8期1022-1028,共7页
This study was to supply the systemic and full milking process data to support the implementation of both dairy herd improvement (DHI) and digital feeding of dairy cattle. This study designed the relational structur... This study was to supply the systemic and full milking process data to support the implementation of both dairy herd improvement (DHI) and digital feeding of dairy cattle. This study designed the relational structured database and developed a set of digital management information system on milking process of intensive dairy farm using Visual Basic 6.0, Access databases, and Crystal report combining the milking characteristics of a grown cow, such as quality and sanitation testing indexes of raw milk. The system supplies a series of convenient, intelligent input interfaces of crude datum, and can count, analyze, and graphically show milking datum based on different types and different parities of cows or herds in a specific duration, and can dynamically produce some important derived data, such as days of grown cow, daily average of milk production of grown cow, days of cow milk production, and daily average of milking cow production; and can carry out all-pervasive data mining. With the help of system analysis and software design techniques, it is possible to realize precision farming for a dairy cattle herd based on whole digital management of milking process and realtime prediction on nutrient requirements and ration of dairy cattle, as well as dairy herd improvement. 展开更多
关键词 dairy farm dairy herd improvement (DHI) grown cow MILKING digital management
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Sustainability Evaluation of Different Systems for Sea Cucumber(Apostichopus japonicus) Farming Based on Emergy Theory 被引量:2
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作者 WANG Guodong DONG Shuanglin +2 位作者 TIAN Xiangli GAO Qinfeng WANG Fang 《Journal of Ocean University of China》 SCIE CAS 2015年第3期503-510,共8页
Emergy analysis is effective for analyzing ecological economic systems. However, the accuracy of the approach is af- fected by the diversity of economic level, meteorological and hydrological parameters in different r... Emergy analysis is effective for analyzing ecological economic systems. However, the accuracy of the approach is af- fected by the diversity of economic level, meteorological and hydrological parameters in different regions. The present study evalu- ated the economic benefits, environmental impact, and sustainability of indoor, semi-intensive and extensive farming systems of sea cucumber (Apostichopus japonicus) in the same region. The results showed that A. japonicus indoor farming system was high in input and output (yield) whereas pond extensive farming system was low in input and output. The output/input ratio of indoor fann- ing system was lower than that of pond extensive farming system, and the output/input ratio of semi-intensive farming system fell in between them. The environmental loading ratio of A.japonicus extensive fanning system was lower than that of indoor farming sys- tem. In addition, the emergy yield and emergy exchange ratios, and emergy sustainability and emergy indexes for sustainable devel- opment were higher in extensive farming system than those in indoor farming system. These results indicated that the current exten- sive farming system exerted fewer negative influences on the environment, made more efficient use of available resources, and met more sustainable development requirements than the indoor farming system. A. japonicus farming systems showed more emergy benefits than fish fanning systems. The pond fanning systems ofA. japonicus exploited more free local environmental resources for production, caused less potential pressure on the local environment, and achieved higher sustainability than indoor farming system. 展开更多
关键词 Apostichopusjaponicas farming systems emergy theory SUSTAINABILITY
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Climate Change Impacts and Adaptation in Rainfed Farming Systems: A Modeling Framework for Scaling-Out Climate Smart Agriculture in Sub-Saharan Africa 被引量:3
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作者 Berhanu F. Alemaw Timothy Simalenga 《American Journal of Climate Change》 2015年第4期313-329,共17页
Improving agricultural water productivity, under rainfed or irrigated conditions, holds significant scope for addressing climate change vulnerability. It also offers adaptation capacity needs as well as water and food... Improving agricultural water productivity, under rainfed or irrigated conditions, holds significant scope for addressing climate change vulnerability. It also offers adaptation capacity needs as well as water and food security in the southern African region. In this study, evidence for climate change impacts and adaptation strategies in rainfed agricultural systems is explored through modeling predictions of crop yield, soil moisture and excess water for potential harvesting. The study specifically presents the results of climate change impacts under rainfed conditions for maize, sorghum and sunflower using soil-water-crop model simulations, integrated based on daily inputs of rainfall and evapotranspiration disaggregated from GCM scenarios. The research targets a vast farming region dominated by heavy clay soils where rainfed agriculture is a dominant practice. The potential for improving soil water productivity and improved water harvesting have been explored as ways of climate change mitigation and adaptation measures. This can be utilized to explore and design appropriate conservation agriculture and adaptation practices in similar agro-ecological environments, and create opportunities for outscaling for much wider areas. The results of this study can suggest the need for possible policy refinements towards reducing vulnerability and adaptation to climate change in rainfed farming systems. 展开更多
关键词 CLIMATE Change ADAPTATION RAINFED farming systems A Modeling CLIMATE SMART AGRICULTURE Southern Africa
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Transitioning from paternalism to empowerment of farmers in lowincome countries: Farming components to systems 被引量:1
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作者 David Norman 《Journal of Integrative Agriculture》 SCIE CAS CSCD 2015年第8期1490-1499,共10页
Reasons for the initiation of farming systems/participatory approaches in non-Green Revolution(i.e., in more heterogeneous and less favourable production environments) areas in low-income countries is followed by a ... Reasons for the initiation of farming systems/participatory approaches in non-Green Revolution(i.e., in more heterogeneous and less favourable production environments) areas in low-income countries is followed by a discussion of their evolution.Four phases are described along, with a brief description of some of the significant methods in which farmer participation has been sought, accessed and evaluated.They enabled/facilitated the evolutionary process.Although, over the last 40 years there has been a progress in making small-scale farmers much more visible in driving the agricultural research/development agenda through using the four basic stages embodied in the farming systems approach(i.e., descriptive, diagnosis, testing/evaluation and finally dissemination), much still needs to be done.This leads on to a discussion as to some of the barriers still inhibiting true farmer empowerment and why further, such empowerment is imperative, if the agricultural challenges of this century are to be addressed successfully, namely substantially increasing agricultural productivity in an ecologically sustainable manner.Given the heterogeneity of the production environments and that many identified improvements are likely to be incremental rather than revolutionary in nature, this will require farmers' intimate involvement in their identification, evaluation and dissemination.Discussion in the paper recognizes that there is increasing globalization/commercialization of agriculture and is predicated on the need to consider the whole farmer-research-development continuum involving multiple stakeholders(i.e., farmers, scientists, extension workers, input/output service providers and policymakers).Such a continuum has been explicitly recognized in the operational plans for the recently reformed international agricultural research(i.e., CGIAR) system.The paper concludes with a short discussion on the potential role of formal modelling. 展开更多
关键词 farming systems research farmer empowerment farmer participatory approaches/techniques globalisation commercialisation conservat
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Efficiency and productivity analysis of vegetable farming within root and tuber-based systems in the humid tropics of Cameroon 被引量:1
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作者 Ajapnwa Akamin Jean-Claude Bidogeza +1 位作者 Jules Rene Minkoua N Victor Afari-Sefa 《Journal of Integrative Agriculture》 SCIE CAS CSCD 2017年第8期1865-1873,共9页
The study analyzes the technical efficiency of vegetable farmers in root and tuber-based farming systems within selected sites of the humid tropics of Cameroon. Multistage sampling was used to collect primary data fro... The study analyzes the technical efficiency of vegetable farmers in root and tuber-based farming systems within selected sites of the humid tropics of Cameroon. Multistage sampling was used to collect primary data from a cross-section of vegetable farmers drawn from eight selected sites in Santa sub division, Northwest region of Cameroon. Stochastic frontier analysis was used to estimate the technical efficiency of vegetable farmer and to examine its determinants. The results showed that farmyard manure was the most productive factor input, followed by farm equipment and labor. The mean technical efficiency level was 67%, revealing production shortfalls and indicating possibilities of significantly increasing production with the current input Jevels. Female, as well as more educated farmers were found to be significantly more efficient than their counterparts. The results also showed that farmers become less technical efficient as farm sizes become larger. Our study findings suggest that smallholder farmers' access to manure, farm implements, and increased women participation in vegetable farming, will produce huge payoffs in vegetable production efficiency in Cameroon. 展开更多
关键词 technical efficiency vegetable productivity farming systems intensification crop diversification stochasticfrontier analysis
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Variations of Farming Systems and Their Impacts on Surface Water Environment in Past 60 Years in Intensive Agricultural Area of Taihu Region, China 被引量:1
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作者 Xinyan Li Hengpeng Li +3 位作者 Guishan Yang Nkotagu Hudson Huan Zhang Xiaofei Nie 《Journal of Water Resource and Protection》 2015年第8期647-658,共12页
Based on agricultural nitrogen (N) balance model and field experiments, the impacts of farming system changes of Taihu Region of China on surface water environment were studied. During past 60 years, farming systems c... Based on agricultural nitrogen (N) balance model and field experiments, the impacts of farming system changes of Taihu Region of China on surface water environment were studied. During past 60 years, farming systems changed greatly in Taihu Region. The traditional method of manure collection and application was replaced by chemical fertilizer utilization gradually. Chemical N fertilization intensity decreased greatly due to the abolition of “3 crops per year” and reduction of cropland area in 1990-2010. Crops depleting soil fertility increased, while those improving soil fertility decreased, leading to an excessive dependence on chemical fertilizer application, which increased the risks of soil N loss to surface water environment in Taihu region. However, field experiments showed that the agricultural N loss with runoff only accounted for 2% of fertilizer N application rate. The majority of N was exported by crop harvesting. Our findings showed that the agricultural N loss might not be the main source of N pollution in Lake Tai after 2000. To control N pollution of Lake Tai, more attention should be paid to industrial and domestic wastewater from urban and rural areas, wastes from livestock and poultry breeding, bait input for aquaculture, etc in the Taihu Region, China. 展开更多
关键词 farmING systems Agricultural Nitrogen BALANCE FERTILIZATION Environmental Pollution Taihu
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Systems of Agriculture Farming in the Uttranchal Himalaya, India 被引量:1
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作者 Vishwambhar Prasad Sati 《Journal of Mountain Science》 SCIE CSCD 2005年第1期76-85,共10页
Agricultural practices are the main stay of the people of Uttranchal. Out of the total population, more than 75% people are engaged either with the main occupation of agriculture or its allied practices, dominated by ... Agricultural practices are the main stay of the people of Uttranchal. Out of the total population, more than 75% people are engaged either with the main occupation of agriculture or its allied practices, dominated by traditional subsistence cereal farming. Among them, the main crops are rice, wheat, millet, barley, all types of pulses, all types of oilseeds and almost all types of fruits. The crops, vegetables and fruits of all varieties are grown in the different climatic zones such as tropical, temperate, and cold because, the region is characterized by the different altitudinal zones elevated from 200 m to more than 8000m. As a result, different climates are found from hot tropical to sub temperate and chilly cold. Pulses varieties are grown extensively. Among vegetables, potato, onion, carrot, all types of green leaf vegetables, brinzal, pumpkin, ladyfinger, pea, gram, radish, ginger, garlic, etc, are grown widely. All fruit varieties are grown in the different altitudinal zones. The main fruits are orange, malta (a big size of orange), elephant citrus, lemon and all other types of citrus, apple, stone fruits including peach and pears, many kinds of nuts, and the fruits which are grown in the low lying areas. In spite of feasible climatic conditions, agricultural dominant society, and availability of all types of crops, the production and productivity of these crops are very low, even they are unable to meet the grain-need of the people in Uttaranchal. Agricultural crops are grown almost in all the altitudinal zones — from the low-lying areas, which are called ‘Gangarh’, to the highly elevated region, where the legendary term is given as ‘Danda’. The growing seasons vary according to the heights. The present paper aims to discuss the agricultural practices including cropping season, cropping pattern, land use, production of crops and ecological aspect of agricultural system in this Himalayan state and suggest some measures for developing farming system, which could lead the sustainability, in terms of meeting the food grain needs of the people on the one hand and restoring the ecological balance on the other. 展开更多
关键词 Mountain farming subsistence cereal farming watershed Alpine meadow valley region highly elevated region sustainability ecological region
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Impact of Wind Farms of DFIG Type on Power System Transient Stability 被引量:2
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作者 Libao Shi Shiqiang Dai +2 位作者 Liangzhong Yao Yixin Ni Masoud Bazargan 《Journal of Electromagnetic Analysis and Applications》 2010年第8期475-481,共7页
The impact of large-scale grid-connected wind farms of Doubly-fed Induction Generator (DFIG) type on power system transient stability is elaborately discussed in this paper. In accordance with an equivalent generator/... The impact of large-scale grid-connected wind farms of Doubly-fed Induction Generator (DFIG) type on power system transient stability is elaborately discussed in this paper. In accordance with an equivalent generator/converter model, the comprehensive numerical simulations with multiple wind farms of DFIG type involved are carried out to reveal the impact of wind farm on dynamic behavior of existing interconnected power system. Different load models involving nonlinear load model and induction motor model are considered during simulations. Finally, some preliminary conclusions are summarized and discussed. 展开更多
关键词 TRANSIENT Stability DFIG Multiple WIND farms WIND farm Integration LOAD Model
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Farming systems and crop-livestock land use consensus. Tanzanian perspectives 被引量:1
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作者 Dunstan Gabriel Msuya 《Open Journal of Ecology》 2013年第7期473-481,共9页
Agriculture is an important source of economic survival of rural populations, and with great power for poverty reduction in the economy. For this reason farming systems that are most efficient have to be sought. This ... Agriculture is an important source of economic survival of rural populations, and with great power for poverty reduction in the economy. For this reason farming systems that are most efficient have to be sought. This paper explores crop-based and pastoralism farming systems under conflicting land use relations. Incidences of violent conflicts are highlighted, which usually assume a depoliticised expression as inter-group conflicts. Competition for resources (land and water) is an important reason for such conflict, but the role of the state in protection of property rights is also advocated to nurture rivalry. Very wide difference in conception, that to the pastoralists property is cattle, land is common property open to herds, while to crop farmers land is property, which is divided between households, complicates the conflict resolution. State bias exists in the protection of property rights. Mechanisms for the state bias arebriefly cited. This paper suggests a farming systems educational approach as a way to reduce environmentally stressful practice, and strengthen the study of administrative regulation that harmonizes equity in conflicting land use. 展开更多
关键词 farmING systems Pastoralism Land Use CHOICES farmer-Herder Conflicts
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