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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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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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Cyber-physical Modeling Technique based Dynamic Aggregation of Wind Farm Considering LVRT Characteristic
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作者 Guiqing Ma Yunlu Li +1 位作者 Junyou Yang Bing Wu 《CES Transactions on Electrical Machines and Systems》 CSCD 2023年第2期229-236,共8页
With the increasing penetration of wind power,large-scale integrated wind turbine brings stability and security risks to the power grid.For the aggregated modeling of large wind farms,it is crucial to consider low vol... With the increasing penetration of wind power,large-scale integrated wind turbine brings stability and security risks to the power grid.For the aggregated modeling of large wind farms,it is crucial to consider low voltage ride-through(LVRT)characteristics.However,in aggregation methods,the approximate neglect behavior is essential,which leads to inevitable errors in the aggregation process.Moreover,the lack of parameters in practice brings new challenges to the modeling of a wind farm.To address these issues,a novel cyber-physical modeling method is proposed.This method not only overcomes the aggregation problem under the black-box wind farm but also accurately realizes the aggregation error fitting according to the operation data.The simulation results reveal that the proposed method can accurately simulate the dynamic behaviors of the wind farm in various scenarios,whether in LVRT mode or normal mode. 展开更多
关键词 Wind farm Aggregated model Low voltage ride through Operation data
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Empirical Study on the Benefit Increase of New Contract Farming 1+3+X Model 被引量:1
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作者 Jiaohu YANG Zhong CHENG +1 位作者 Hao ZHOU Peter ZHANG 《Asian Agricultural Research》 2020年第4期7-13,33,共8页
For a long time,the development model of traditional rice planting industry has been single,linear,and focusing on production first and then market.However,with the low price of rice,such problems as slow technologica... For a long time,the development model of traditional rice planting industry has been single,linear,and focusing on production first and then market.However,with the low price of rice,such problems as slow technological upgrading,meager profits,and unstable rice quality in the primary industry planting units and farmers have become increasingly prominent.The integration and development of the rural primary,secondary,and tertiary industries and industrial integration have the same root.They are integrated industrial development based on technological or model innovation,vertical and horizontal integration.Three agricultural leading companies(Nanjing Tianwei Agricultural Technology Co.,Ltd.,Nanjing CHYKINGYOUNG Biological Technology Co.,Ltd.,and Jiangsu Jingshan Eco-organic Agriculture Co.,Ltd.)established an industrialization complex,and used their respective technical,operational,and market advantages to integrate and form a rice contract farming 1+3+X model.This model effectively integrates scattered rice planting,rice processing,and rice sales in Nanjing City of Jiangsu Province,and Chuzhou City of Anhui Province,and unifies planting regulations and supply of production materials,safeguards the supply of green and high-quality rice and realizes high quality and high price.In addition,it integrates farmers into the entire industrial chain of contract farming,summons up the production enthusiasm of farmers and greatly increases their income from planting production. 展开更多
关键词 Integration of primary secondary and TERTIARY industries Contract farming Green and high quality Benefit INCREASE from multiple dimensions 1+3+X model Rice PLANTING Menghu Intelligent
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A nonlinear wake model of a wind turbine considering the yaw wake steering
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作者 Yunzhou LI Zhiteng GAO +2 位作者 Shoutu LI Suiping QI Xiaoyu TANG 《Journal of Oceanology and Limnology》 SCIE CAS CSCD 2024年第3期715-727,共13页
Duo to fluctuations in atmospheric turbulence and yaw control strategies,wind turbines are often in a yaw state.To predict the far wake velocity field of wind turbines quickly and accurately,a wake velocity model was ... Duo to fluctuations in atmospheric turbulence and yaw control strategies,wind turbines are often in a yaw state.To predict the far wake velocity field of wind turbines quickly and accurately,a wake velocity model was derived based on the method of momentum conservation considering the wake steering of the wind turbine under yaw conditions.To consider the shear effect of the vertical incoming wind direction,a two-dimensional Gaussian distribution function was introduced to model the velocity loss at different axial positions in the far wake region based on the assumption of nonlinear wake expansion.This work also developed a“prediction-correction”method to solve the wake velocity field,and the accuracy of the model results was verified in wake experiments on the Garrad Hassan wind turbine.Moreover,a 33-kW two-blade horizontal axis wind turbine was simulated using this method,and the results were compared with the classical wake model under the same parameters and the computational fluid dynamics(CFD)simulation results.The results show that the nonlinear wake model well reflected the influence of incoming flow shear and yaw wake steering in the wake velocity field.Finally,computation of the wake flow for the Horns Rev offshore wind farm with 80 wind turbines showed an error within 8%compared to the experimental values.The established wake model is less computationally intensive than other methods,has a faster calculation speed,and can be used for engineering calculations of the wake velocity in the far wakefield of wind turbines. 展开更多
关键词 far wake wake model wake steering wind shear wind farm
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Farm buildings and agri-food transitions in Southern France:Mapping dynamics using a stakeholder-based diagnosis
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作者 Orlane Rouquier Coline Perrin +1 位作者 Michaël Pouzenc Valérie Olivier-Salvagnac 《Geography and Sustainability》 CSCD 2024年第1期108-120,共13页
This study's goal is to present a dynamic portrait of the farm-buildings environment in Occitania,in Southern France,in order to better identify the transitions underway in agri-food chains.To this end,we undertoo... This study's goal is to present a dynamic portrait of the farm-buildings environment in Occitania,in Southern France,in order to better identify the transitions underway in agri-food chains.To this end,we undertook a ter-ritorial diagnosis based on actor statements,using 28 semi-structured interviews across Occitania.This diagnosis was enriched by graphic modelling,which enabled the spatialization of the dynamics described.We show that the process of standardisation of farm buildings prevails in the majority of the territories studied.This phenomenon has intensified in recent years with the development of vast photovoltaic-roofed sheds,accentuating the farm-land conversion and soil sealing.At the same time,in areas with strong environmental,landscape and heritage contexts,a'new adventure in farm buildings'(2022 survey)is taking shape.It is primarily driven by local short food chains,which rely on self-construction,repurposing and refurbishment,the sharing of tools and equipment,and which favour the use and reuse of local resources.This study shows that farm-buildings dynamics crystallise many challenges confronting the reterritorialisation of agriculture and food production. 展开更多
关键词 farm buildings TRANSITION Local food systems Occitania Cartographic modelling
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Modeling Farm Management Modernization: Case Study of Japanese Rice Farming Corporations
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作者 Yukio Kinoshita Nobuo Kimura 《Journal of Agricultural Science and Technology(B)》 2016年第5期307-320,共14页
While conventional family-owned and family-operated farms remain the most common structure, the number of Japanese agricultural corporations has increased in recent years as a result of changing policies. Some of them... While conventional family-owned and family-operated farms remain the most common structure, the number of Japanese agricultural corporations has increased in recent years as a result of changing policies. Some of them are possibly starting to adopt modem corporate management practices to remain viable in a more competitive environment. However, changes in the business structure have not always been accompanied by changes in farm management practices. This study represents a theoretical and empirical investigation into farm modernization practices to provide perspective and recommendations to enhance farm business. Various aspects of farm modernization were considered, including temporal, economic and functional modernization. Critical elements of farm modernization were examined using a structural equation model of surveys, wherein questionnaires were delivered to 2,260 agricultural corporations across Japan in 2014 and 2016, generating 669 usable responses from rice farming corporations. Overall, these corporations demonstrated moderate degrees of modernization, indicating that they have not yet completely transitioned from conventional management styles to modem corporate management and that the farm-household complex system still exists for many of them. It was also found that farm modernization is significantly affected by both production and business management systems, although it was unclear whether a farmer's managerial capabilities were critical for farm modernization. The findings of this study indicate that current farming corporations may benefit from incorporating additional modernization practices. The analytical framework and results will help farmers to better understand their management practices and can be used to provide ideas for policy development to promote competitive farm businesses. 展开更多
关键词 farm business farming corporations modernization of management structural equation model.
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基于PSModel的海上风电场全电磁暂态建模与仿真
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作者 崔森 郁舒雁 《电网技术》 EI CSCD 北大核心 2024年第1期262-271,共10页
开发有效的风机电磁暂态模型是进行海上风电并网研究的基础。根据不同生产厂家所提供的直驱风机模型,提出了一种基于厂家黑盒模型的直驱风机电磁暂态建模方法。利用厂家所提供的模型测试数据解析风机的故障响应特性,推导了不同厂家在电... 开发有效的风机电磁暂态模型是进行海上风电并网研究的基础。根据不同生产厂家所提供的直驱风机模型,提出了一种基于厂家黑盒模型的直驱风机电磁暂态建模方法。利用厂家所提供的模型测试数据解析风机的故障响应特性,推导了不同厂家在电压故障下有功和无功功率响应表达式,包括故障期间的穿越控制过程及不同过程间的暂态切换策略。提出了加权平均压降的风电场等值方法,采用自主研发的全电磁暂态仿真软件(power system model,PSModel)对我国广东某海上风电场进行全电磁暂态建模。根据稳态潮流及暂态特性结果验证了模型可通过系统测试,且有效实现了海上风电场的全电磁暂态建模,从而为该风场接入大电网后的安全稳定分析提供了研究基础。 展开更多
关键词 直驱风电机组 黑盒模型 海上风电场 PSmodel 故障穿越
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AIC-Based Selection of Growth Models: The Case of Piglets from Organic Farming
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作者 Katharina Renner-Martin Manfred Kühleitner +1 位作者 Norbert Brunner Werner Hagmüller 《Open Journal of Modelling and Simulation》 2016年第2期17-23,共7页
The selection and comparison of different growth models for describing weight gain of piglets raised in organic farming is investigated by using the Akaike’s Information Criterion (AIC). In total, 49,699 data points ... The selection and comparison of different growth models for describing weight gain of piglets raised in organic farming is investigated by using the Akaike’s Information Criterion (AIC). In total, 49,699 data points of 5188 piglets recorded between 2007 and 2013 were considered. From the day of birth, up to 40 days (i.e. until weaning) the model of von Bertalanffy was favored by the AIC. This model is with 60.32% more likely to truly reflect reality than any other of the analyzed models. Up to 105 days, the two-linear model was favored by the AIC (probability 99.75%). The intersection point of the two-linear model was calculated by 53.8 days, which fitted well to the actual change in the food situations. 展开更多
关键词 AIC Growth Curve Growth model Weight Gain PIGLET Organic farming
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Construction of Risk Assessment Application Model of Epidemic Disease in Large-scale Pig Farms 被引量:1
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作者 谭业平 刘强 +3 位作者 胡肄农 郁达威 何孔旺 陆昌华 《Agricultural Science & Technology》 CAS 2016年第9期2124-2126,共3页
The application model of epidemic disease assessment technology for Web-based large-scale pig farm was expounded from the identification of epidemic disease risk factors, construction of risk assessment model and deve... The application model of epidemic disease assessment technology for Web-based large-scale pig farm was expounded from the identification of epidemic disease risk factors, construction of risk assessment model and development of risk assessment system. The assessed pig farm uploaded the epidemic disease risk data information through on-line answering evaluating questionnaire to get the immediate evaluation report. The model could enhance the risk communication between pig farm veterinarian, manager and veterinary experts to help farm system understand and find disease risk factors, assess and report the potential high risk items of the pig farm in the three systems of engineering epidemic disease prevention technology, biological safety and immune monitoring, and promote the improvement and perfection of epidemic disease prevention and control measures. 展开更多
关键词 Large-scale pig farm Risk assessment of epidemic disease model construction
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基于遗传Data Farming的公共政策优化仿真模型 被引量:1
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作者 彭敏晶 林健 《系统仿真学报》 EI CAS CSCD 北大核心 2008年第21期5963-5966,5988,共5页
为了解决公共政策优化仿真时考察点不全面及耗费时间大的问题,提出了基于遗传Data Farming的公共政策优化仿真模型。所提出的模型中,Data Farming被用于全面地考察输入参数空间中各输入参数水平对应的输出响应,通过把仿真过程的输出过... 为了解决公共政策优化仿真时考察点不全面及耗费时间大的问题,提出了基于遗传Data Farming的公共政策优化仿真模型。所提出的模型中,Data Farming被用于全面地考察输入参数空间中各输入参数水平对应的输出响应,通过把仿真过程的输出过程看作适应度的计算,遗传算法被用于优化仿真过程,提高优化效率。分析了公共政策作用效果的影响因素,并介绍了传统的Data Farming技术,然后从仿真目标、模型框架、算法等三方面介绍了所提出的优化仿真模型。最后进行了实验,证明了所提出模型的有效性。 展开更多
关键词 DATA farming 遗传算法 公共政策 仿真模型 适应度
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Model Farm Services Center Approach: An Implication to Boost Farmer’s Yield
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作者 Rehmat Ullah Muhammad Zafarullah Khan +1 位作者 Kalim Ullah Tahir Munir Butt 《Agricultural Sciences》 2015年第9期953-960,共8页
The instant study was conducted to estimate the Model Farm Services Center’s (MFSC) contribution in yield improvement of major crops/vegetables in district Dera Ismail Khan, Khyber Pakhtunkhwa, Pakistan, during the y... The instant study was conducted to estimate the Model Farm Services Center’s (MFSC) contribution in yield improvement of major crops/vegetables in district Dera Ismail Khan, Khyber Pakhtunkhwa, Pakistan, during the year 2014-15. Based on Sekaran sampling technique 306 respondents were selected and were personally interviewed through well prepared and pre-tested interview schedule. To find out the actual performance of yield improvement by Model Farm Services Center along with other repressors, step by step analysis was performed. The results of Wilcoxon Sign Rank Test showed significant improvement in yield of sugarcane, wheat, maize, rice and tomato by Model Farm Services Center. Pearson’s correlation coefficient showed highly significant positive relation of sugarcane and wheat yield difference before and after Model Farm Services Center registration with MFSC. Ordinary Least Square Multiple-Regression Model indicates that MFSC registration duration and landholding significantly define the variation in dependent variables at 1% and 5% level of significance respectively for sugarcane yield. Whereas solely Model Farm Services Center registration duration profoundly highly significantly (P ≤ 0.01) explains the variation in dependent variables in wheat yield. 展开更多
关键词 model farm SERVICES CENTER SUGARCANE Wheat Pakistan
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Research on Influence Factors of Pig Farmers' Ecological Farming Behavior: Based on the TPB and SEM
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作者 Chengying HAN Zhenhong QI +1 位作者 Dongmin ZHANG Xinrui LI 《Asian Agricultural Research》 2016年第2期19-27,共9页
China's extensive development model of pig industry gives rise to serious resource and environment bottleneck restriction,it is urgent to transform the existing development model into ecological farming model. In ... China's extensive development model of pig industry gives rise to serious resource and environment bottleneck restriction,it is urgent to transform the existing development model into ecological farming model. In this process,farmers' behavior will play a key role. On the basis of summarizing development connotation and characteristics of ecological agriculture,using survey data of 323 pig farmers in 6 provinces,based on the Theory of Planned Behavior( TPB) it introduced individual characteristics and external environment constraint variables,and made an empirical analysis on factors influencing intention and behavior of pig farmers' ecological farming using the Structural Equation Model( SEM). Results indicate:( i) ecological farming intention of pig farmers has the largest direct effect on their ecological farming behavior;( ii)ecological farming cognition of pig farmers has significant positive effect on their ecological farming behavior;( iii) external environment has the largest indirect effect on their ecological farming behavior,followed by the overall effect,and external environment has significant positive effect on ecological farming attitude and cognition of pig farmers;( iv) individual characteristics( educational level and income level) of pig farmers influence ecological farming behavior of pig farmers through their ecological farming attitude and intention,but the degree of influence is limited. 展开更多
关键词 Ecological farming BEHAVIOR Influence factors PIG farmERS Theory of PLANNED Behavior(TPB) Structural Equation model(SEM)
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A Study on the Operating Model of Internet + QQ Farm
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作者 Yuyu ZHANG Chengjian YONG +4 位作者 Zhixing WU Jinzhu HUA Jiani LIU Jingxiang HU Liyuan YAO 《Asian Agricultural Research》 2017年第6期11-12,18,共3页
The'Internet+QQ farm'creative agriculture presented in this paper is the innovation based on the currently booming reality QQ farm,aimed at reducing cost,improving efficiency and optimizing human and material ... The'Internet+QQ farm'creative agriculture presented in this paper is the innovation based on the currently booming reality QQ farm,aimed at reducing cost,improving efficiency and optimizing human and material resource elements.It can make Internet provide technical support for intelligence-based life,leisure,entertainment,with good prospects for development. 展开更多
关键词 Internet + QQ farm Leisure agriculture Creative agriculture Operating model
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Spatial Analysis and Modelling of Wind Farm Site Suitability in Nasarawa State, North-Central Nigeria
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作者 Chukwunonso Emmanuel Ozim Anita Odionyenfe Nweke +3 位作者 Salamatu Abraham Ekpo Olufemi Stephen Oladeinde Haruna Kuje Ayuba Udochukwu Michael Mbanaso 《Journal of Geographic Information System》 2021年第5期603-630,共28页
There has been an increasing global and local interest in developing renewable, clean, and cheap energy towards achieving Goal number 7 of the Sustainable Development Goals (SDG). However, decisions involving suitable... There has been an increasing global and local interest in developing renewable, clean, and cheap energy towards achieving Goal number 7 of the Sustainable Development Goals (SDG). However, decisions involving suitable and sustainable locations for renewable energy projects remain an important task. This study employed Geographic Information System (GIS) and Multi-Criteria Decision Analysis (MCDA) to spatially analyze and model wind farm site suitability in Nasarawa State. The aim is to integrate the environmental, social, and economic aspects of decision-making for identifying sustainable wind farm sites. The study distinguished between two sets of decision criteria: decision constraints and decision factors. The former defined the exclusion zones while the latter were standardized based on fuzzy logic to depict varying degrees of suitability across the State. The MCDA applied the weighted linear combination method, with relative weights generated through pairwise comparisons of the analytic hierarchy process to analyze three policy scenarios: equal weights, environmental/social priority, and economic priority scenario. A combination of resulting composite maps from the constraints and the factors gave the final suitability maps. The resulting suitability index (SI) for the respective policy scenario describes the degrees of suitability: Ideal locations were denoted by one (1) and the not suitable locations by zero (0), with values in-between depicting varying degrees of wind farm site suitability. Based on the SI, priority locations indicating areas with good prospects, in addition to the most suitable parcels of land, were identified and delineated. The composite decision constraint revealed that wind farm projects would not be viable in more than half (57.58%) of the State. Wind speed was the major constraint and accounted for the exclusion of 46.25%, with a mean fuzzy membership value of 0.2008 indicating low suitability across the State. Also, the average acceptable wind farm location for the three-policy scenario was 33.33% of the entire study area. Lafia, Obi, Keana, Awe, Nasarawa-Eggon, Wamba and Kokona LGAs were the identified priority Local Government Areas (LGAs). However, only Lafia, Obi, and Nasarawa-Eggon were consistent with changes in the policy objectives. All the priority LGAs have one or more of the most suitable parcels within their administrative boundaries except for Wamba. Despite the severe limitations of wind speed, substantial parts of Nasarawa State still provide great development potentials for wind energy. The “most suitable” locations in Lafia, Nasarawa-Eggon, and Obi LGAs should have first consideration for the development of wind energy in the State. 展开更多
关键词 GIS Multi-Criteria Spatial Analysis and modelling Wind Energy farm Site Suitability Nasarawa State Nigeria
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Agriculture Technology as a Tool to Influence Youth Farming in Ghana
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作者 Benjamin Danso Kwakye Robert Brenya +2 位作者 Derrick Acquanah Cudjoe Agyemang Kwasi Sampene Fredrick Oteng Agyeman 《Open Journal of Applied Sciences》 2021年第8期885-898,共14页
The extent of engagement of the youth going into farming is steadily seen as the modern-day panacea for sustainability and extenuation of food insecurity. Yet, this plodding-shift of the youth has opened new doors for... The extent of engagement of the youth going into farming is steadily seen as the modern-day panacea for sustainability and extenuation of food insecurity. Yet, this plodding-shift of the youth has opened new doors for a different problem that needs efficient agricultural resolution. The study examines the correlation between youth farming and the various factors that influence the youth to go into agriculture using data obtained from the Ghanaian youth. We applied Explanatory Factor Analysis (EFA) of the paradigms, with principal component factoring. The results justified using Confirmatory Factor Analysis (CFA) in AMOS and R. The results showed that technology outperforms factors such as motivation, economics, and government policies to significantly influence the youth towards farming. Attitude and knowledge were also found to have an indirect influence on youth farming. The paper contributes to the theoretical influence of technology on the youth and on the practicality of agricultural farming. 展开更多
关键词 AGRICULTURE Explanatory Factor Analysis Structural Equation modeling Technology Youth farming
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Research on Equivalent Modeling Method of AC-DC Power Networks Integrating with Renewable Energy Generation
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作者 Weigang Jin Lei Chen +3 位作者 Yifei Li Shencong Zheng Yuqi Jiang Hongkun Chen 《Energy Engineering》 EI 2023年第11期2469-2487,共19页
Along with the increasing integration of renewable energy generation in AC-DC power networks,investigating the dynamic behaviors of this complex system with a proper equivalent model is significant.This paper presents... Along with the increasing integration of renewable energy generation in AC-DC power networks,investigating the dynamic behaviors of this complex system with a proper equivalent model is significant.This paper presents an equivalent modeling method for the AC-DC power networks with doubly-fed induction generator(DFIG)based wind farms to decrease the simulation scale and computational burden.For the AC-DC power networks,the equivalent modeling strategy in accordance with the physical structure simplification is stated.Regarding the DFIG-based wind farms,the equivalent modeling based on the sequential identification of multi-machine parameters using the improved chaotic cuckoo search algorithm(ICCSA)is conducted.In light of the MATLAB simulation platform,a two-zone four-DC interconnected power grid with wind farms is built to check the efficacy of the proposed equivalentmodelingmethod.Fromthe simulation analyses and comparative validation in different algorithms and cases,the proposed method can precisely reflect the steady and dynamic performance of the demonstrated system under N-1 and N-2 fault scenarios,and it can efficiently achieve the parameter identification of the wind farms and fulfill the equivalent modeling.Consequently,the proposed approach’s effectiveness and suitability are confirmed. 展开更多
关键词 Equivalent modeling AC-DC power networks renewable energy generation wind farm improved chaotic cuckoo search algorithm
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海上风电场经交流海缆并网谐波谐振放大分析 被引量:1
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作者 顾文 郑超航 +3 位作者 杨宏宇 吴熙 汪泓 许皓珲 《现代电力》 北大核心 2024年第2期380-391,共12页
采用交流海缆接入电网的海上风电场在电缆线路分布电容的作用下,可能出现陆上风电场不常见的谐波谐振与谐波放大现象,严重威胁到海上风电场安全可靠运行。为研究海上风电场谐波谐振机理与谐波放大影响因素,首先,建立了海上风电场输电系... 采用交流海缆接入电网的海上风电场在电缆线路分布电容的作用下,可能出现陆上风电场不常见的谐波谐振与谐波放大现象,严重威胁到海上风电场安全可靠运行。为研究海上风电场谐波谐振机理与谐波放大影响因素,首先,建立了海上风电场输电系统与集电系统两部分的状态空间模型,并给出谐波放大倍数、谐波含量等指标的计算方法;其次,通过特征值和参与因子揭示了谐波谐振机理及关键影响因素;然后,通过根轨迹法研究了电网短路容量、高压电缆参数和风电机组并网台数对谐振模态的影响;最后,在Matlab/Simulink仿真平台搭建江苏某海上风电场.验证理论分析的有效性。 展开更多
关键词 海上风电场 状态空间模型 谐波谐振机理 谐波放大
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计及低电压穿越及故障全过程动态的双馈风电场等值方法 被引量:1
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作者 周海强 崔晓丹 +3 位作者 许剑冰 曹博源 高超 陈志昊 《电力系统自动化》 EI CSCD 北大核心 2024年第6期216-225,共10页
在分析双馈感应发电机(DFIG)故障各阶段动态的基础上,提出了一种计及低电压穿越控制的双馈风电场等值方法。首先,讨论了低电压穿越控制策略,给出了含双馈风电场的电力系统故障稳态潮流计算方法。在考虑电压暂态过程的条件下,分析了外部... 在分析双馈感应发电机(DFIG)故障各阶段动态的基础上,提出了一种计及低电压穿越控制的双馈风电场等值方法。首先,讨论了低电压穿越控制策略,给出了含双馈风电场的电力系统故障稳态潮流计算方法。在考虑电压暂态过程的条件下,分析了外部系统短路故障后DFIG转子电流的变化机理,指出电压跌落深度及风电功率是影响短路电流的主要因素,可根据动作分界线判断撬棒是否动作。然后,根据初始风速及撬棒状态将风电场中的DFIG分为3群,并对等值DFIG及集电网络进行聚合。为提高等值模型在恢复阶段的精度,根据故障稳态电压对双馈风电场功率恢复曲线进行预估,并在此基础上对等值DFIG恢复速率进行分段修正。最后,对含双馈风电场的算例系统进行了等值计算。仿真结果表明,等值模型较好地保持了原系统在故障各阶段的动态,在保持较高精度的前提下有效简化了系统,提高了计算速度。 展开更多
关键词 双馈感应发电机 风电场 低电压穿越 电力潮流 撬棒 动态等值 等值模型 功率恢复
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新农科背景下“BOPPPS+在线资源”模式在耕作学中的改革与实践 被引量:1
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作者 马鹏 兰艳 +3 位作者 黄晶 车明轩 白银萍 张荣萍 《智慧农业导刊》 2024年第2期121-124,共4页
随着国家实施乡村振兴战略,加快推进农业转型升级和农业现代化的建设,对高等农业院校农业人才培养和教育教学提出更高的要求。为有效提高农学专业课程的教学效果,培养适合社会需求的素质高、技能精、实践强、有担当且敢于迎接挑战并坚... 随着国家实施乡村振兴战略,加快推进农业转型升级和农业现代化的建设,对高等农业院校农业人才培养和教育教学提出更高的要求。为有效提高农学专业课程的教学效果,培养适合社会需求的素质高、技能精、实践强、有担当且敢于迎接挑战并坚持创新的新农科人才。该文以农学专业核心课程耕作学教学为对象,设计并实践“BOPPPS+在线资源”的混合式教学模式,该模式将学科文化和学科发展与思政教育结合、理论知识与生产实践结合、线下与线上教育资源结合。该模式能够优化创新学习策略,构建新农科背景下课上“活跃”课下“忙碌”的混合式教学新模式,有效提高耕作学的教学质量,为培养高素质应用型新农科人才提供重要的参考依据。 展开更多
关键词 新农科 耕作学 混合式教学模式 效果分析 人才培养
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