A parachute-payload model with randomize wind gust is developed to study the landing accuracy of the parachute decelerator system,which can be exactly described by the landing site distribution.The research focuses on...A parachute-payload model with randomize wind gust is developed to study the landing accuracy of the parachute decelerator system,which can be exactly described by the landing site distribution.The research focuses on the steady descent phase of the parachute descent process,so the parachute and the payload suspension formulation during the phase are mainly discussed.In addition,since the wind effects have a significant impact on the land site distribution of the passive decelerator system and it is difficult to obtain the exact wind profile in practice,major features of parachute-payload system are studied via the randomized wind gust formulation.As the randomized wind gust formulation is adopted,the wind effect can be considered without the exact wind gust profile and the parachute aerodynamic simulation can be fulfilled with uncertainties.Finally,the model is validated and discussed,and the parachute land site distributions with different wind randomize profiles are presented for comparison.The results show that when parachute is less stable,the land site tends to have a larger variance.展开更多
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
The aim of this study was to identify potential sites for wind turbine in the North West of Jordan. The Analytic Hierarchy Process (AHP) was used in a novel approach to identify the potential sites for the wind turbin...The aim of this study was to identify potential sites for wind turbine in the North West of Jordan. The Analytic Hierarchy Process (AHP) was used in a novel approach to identify the potential sites for the wind turbine in the study area based on five physical criteria (Wind Speed, Rainfall, Slope, Altitude and Land use) that affect the wind turbine sites. The importance of each criterion was based on experts’ opinions. The ratings for each criterion were based on the available literature review. The consistency ratio between the experts’ opinions was evaluated using the pairwise comparison method and a final weight was computed for each criterion. A wind turbine suitability map was generated using the weighted linear combination (WLC) method within GIS environment. It was found that 45% of the study area has high and very high suitability for wind turbine. In conclusion, this research will contribute to the enhancement of the available renewable energy resources in Jordan if the selected sites will be utilized for wind turbine.展开更多
随着射电望远镜口径增大、观测频率提高,对其指向精度的要求也越来越高.然而,望远镜服役于野外台站,台址风扰对天线指向精度的影响在高频段观测时已不能忽略.由于风扰的时变性,现有的抗风方法无法保障大口径高指向精度望远镜在高频段的...随着射电望远镜口径增大、观测频率提高,对其指向精度的要求也越来越高.然而,望远镜服役于野外台站,台址风扰对天线指向精度的影响在高频段观测时已不能忽略.由于风扰的时变性,现有的抗风方法无法保障大口径高指向精度望远镜在高频段的有效观测时长.因此,提出了一种基于风障精确布置改善台址风环境的方法.通过数值模拟构建了风障仿真模型,并将仿真结果与风洞实测数据比较,两种孔隙率风障的平均误差分别为3.7%和6.1%,保证了风障模型的可靠性.以新疆奇台射电望远镜(QiTai radio Telescope,QTT)台址为例,基于QTT台址斜坡地形构建了计算域模型,开展单风障不同高度、不同孔隙率的系列风场仿真试验,得到了风障参量与下游挡风效果的关系.基于单风障合理高度和最优孔隙率设置南北风障,仿真结果表明在确定高度下最优孔隙率可以组合,孔隙率0.1-0.1组合的风障挡风效果最优,南方向来风在天线区域可以有效降低75%以上的风速.展开更多
This paper introduced the status quo of wind power and wind power generation technology. Focusing on the introduction of wind power generating system ibrational self-consistent field（VSCF）, program implementation in...This paper introduced the status quo of wind power and wind power generation technology. Focusing on the introduction of wind power generating system ibrational self-consistent field（VSCF）, program implementation included Alternating Current （AC）-Direct Current （DC）-AC conversion system, magnetic field modulation generator system, doubly-fed generator system etc. Among these, doubly-fed generator system is the trend. Where to build the wind farm is very important, so a perfect site is needed. Wind power generation will have a bright future. As long as the wind power can be linked to the grid in large scale.展开更多
基金supported by the National Natural Science Foundation of China(No.11472137)the Educational Commission of Guangdong Province(No.2017KQNCX203)Science and Technology Project of Guangdong Province (No. 2016A010102023,2017A010102017)
文摘A parachute-payload model with randomize wind gust is developed to study the landing accuracy of the parachute decelerator system,which can be exactly described by the landing site distribution.The research focuses on the steady descent phase of the parachute descent process,so the parachute and the payload suspension formulation during the phase are mainly discussed.In addition,since the wind effects have a significant impact on the land site distribution of the passive decelerator system and it is difficult to obtain the exact wind profile in practice,major features of parachute-payload system are studied via the randomized wind gust formulation.As the randomized wind gust formulation is adopted,the wind effect can be considered without the exact wind gust profile and the parachute aerodynamic simulation can be fulfilled with uncertainties.Finally,the model is validated and discussed,and the parachute land site distributions with different wind randomize profiles are presented for comparison.The results show that when parachute is less stable,the land site tends to have a larger variance.
文摘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.
文摘The aim of this study was to identify potential sites for wind turbine in the North West of Jordan. The Analytic Hierarchy Process (AHP) was used in a novel approach to identify the potential sites for the wind turbine in the study area based on five physical criteria (Wind Speed, Rainfall, Slope, Altitude and Land use) that affect the wind turbine sites. The importance of each criterion was based on experts’ opinions. The ratings for each criterion were based on the available literature review. The consistency ratio between the experts’ opinions was evaluated using the pairwise comparison method and a final weight was computed for each criterion. A wind turbine suitability map was generated using the weighted linear combination (WLC) method within GIS environment. It was found that 45% of the study area has high and very high suitability for wind turbine. In conclusion, this research will contribute to the enhancement of the available renewable energy resources in Jordan if the selected sites will be utilized for wind turbine.
文摘随着射电望远镜口径增大、观测频率提高,对其指向精度的要求也越来越高.然而,望远镜服役于野外台站,台址风扰对天线指向精度的影响在高频段观测时已不能忽略.由于风扰的时变性,现有的抗风方法无法保障大口径高指向精度望远镜在高频段的有效观测时长.因此,提出了一种基于风障精确布置改善台址风环境的方法.通过数值模拟构建了风障仿真模型,并将仿真结果与风洞实测数据比较,两种孔隙率风障的平均误差分别为3.7%和6.1%,保证了风障模型的可靠性.以新疆奇台射电望远镜(QiTai radio Telescope,QTT)台址为例,基于QTT台址斜坡地形构建了计算域模型,开展单风障不同高度、不同孔隙率的系列风场仿真试验,得到了风障参量与下游挡风效果的关系.基于单风障合理高度和最优孔隙率设置南北风障,仿真结果表明在确定高度下最优孔隙率可以组合,孔隙率0.1-0.1组合的风障挡风效果最优,南方向来风在天线区域可以有效降低75%以上的风速.
文摘This paper introduced the status quo of wind power and wind power generation technology. Focusing on the introduction of wind power generating system ibrational self-consistent field（VSCF）, program implementation included Alternating Current （AC）-Direct Current （DC）-AC conversion system, magnetic field modulation generator system, doubly-fed generator system etc. Among these, doubly-fed generator system is the trend. Where to build the wind farm is very important, so a perfect site is needed. Wind power generation will have a bright future. As long as the wind power can be linked to the grid in large scale.
