Accurate forecasting of wind velocity can improve the economic dispatch and safe operation of the power system. Support vector machine (SVM) has been proved to be an efficient approach for forecasting. According to th...Accurate forecasting of wind velocity can improve the economic dispatch and safe operation of the power system. Support vector machine (SVM) has been proved to be an efficient approach for forecasting. According to the analysis with support vector machine method, the drawback of determining the parameters only by experts' experience should be improved. After a detailed description of the methodology of SVM and simulated annealing, an improved algorithm was proposed for the automatic optimization of parameters using SVM method. An example has proved that the proposed method can efficiently select the parameters of the SVM method. And by optimizing the parameters, the forecasting accuracy of the max wind velocity increases by 34.45%, which indicates that the new SASVM model improves the forecasting accuracy.展开更多
为研究不同容量风力机尾流的相互作用情况,该文通过致动线模型(actuator line model,ALM)耦合大涡模拟(large eddy simulation,LES)的方法对串列布置两台容量不一的水平轴风力机在不同流向间距下的尾流场进行数值模拟,分析尾流场速度分...为研究不同容量风力机尾流的相互作用情况,该文通过致动线模型(actuator line model,ALM)耦合大涡模拟(large eddy simulation,LES)的方法对串列布置两台容量不一的水平轴风力机在不同流向间距下的尾流场进行数值模拟,分析尾流场速度分布、涡量分布、频谱特性以及尾涡演变情况。结果表明,随着下游风力机的容量和几何尺寸的增加,尾流区速度波动越大,上下游风力机尾流掺混强度增强,掺混后的涡结构向上偏转程度加剧,使垂向尾流发展更加均匀,湍动能也较大;随着流向间距的增加,下游风力机的尾流受上游风力机轮毂中心涡的卷吸作用减弱,受下叶尖涡和塔筒脱落涡的裹挟输运作用增加。总体来讲,大小容量不同的风力机的尾流掺混能在一定程度上加速尾流的恢复,但是需要一定的发展空间来使其克服下游风力机产生的进一步速度亏损的影响,该文中的发展空间为6~8D。展开更多
考虑到山谷气流的复杂性,我们在山地云雾物理研究和人工影响天气作业中,需要更加关注低层风廓线及垂直气流的观测研究。本文针对我国庐山云雾试验站的山谷地形及其与庐山气象站的85 m高度落差特点,利用2019年11、12月云雾试验站测风激...考虑到山谷气流的复杂性,我们在山地云雾物理研究和人工影响天气作业中,需要更加关注低层风廓线及垂直气流的观测研究。本文针对我国庐山云雾试验站的山谷地形及其与庐山气象站的85 m高度落差特点,利用2019年11、12月云雾试验站测风激光雷达的40~260 m高度风廓线和气象站10 m风的联合观测,分析了山谷低层风廓线特征、垂直运动与水平气流的关系及其影响因素。结果表明:(1)云雾试验站80 m高度与气象站10 m高度的风速和风向相关性较好,该高度的垂直速度和水平风速分别以±0.5 m s^(-1)、2~4 m s^(-1)为主。(2)云雾试验站所处山谷的平均风速随高度递增,白天风速在各高度上均低于夜间;昼夜风速差随高度增大,80 m(40 m)高度的昼夜风速差分别为-1 m s^(-1)(-0.2 m s^(-1))。(3)山谷低层垂直运动的方向主要与山谷开口方向及气流来向有关,与气流强度的关系不大;垂直速率大小与水平风速成正比。如云雾试验站80 m高度偏南风(风向112.5°~247.5°)上升气流占主导,其余风向下沉气流占主导,该关系可延展到260 m高度。(4)山谷低层气流弱风向切变可导致垂直运动分层,反映了山谷地形气流比平原更复杂。展开更多
In order to improve structure performance of the dish solar concentrator,a three-dimensional model of dish solar concentrator was established based on the high-precision numerical algorithms.And a virtual wind tunnel ...In order to improve structure performance of the dish solar concentrator,a three-dimensional model of dish solar concentrator was established based on the high-precision numerical algorithms.And a virtual wind tunnel experiment with constant wind is adopted to investigate the pressure distribution of the reflective surface,velocity distribution of the fluid domain for the dish solar concentrator in different poses and wind speeds distribution.Some results about wind pressure distribution before and after dish solar concentrator surface and wind load velocity distribution in the entire fluid domain had been obtained.In particular,it is necessary to point out that the stiffness at the center of the dish solar concentrator should be relatively raised.The results can provide a theoretical basis for the improvement of solar concentrator dish structure as well as the failure analysis of dish solar concentrator in engineering practice.展开更多
基金Project(71071052) supported by the National Natural Science Foundation of ChinaProject(JB2011097) supported by the Fundamental Research Funds for the Central Universities of China
文摘Accurate forecasting of wind velocity can improve the economic dispatch and safe operation of the power system. Support vector machine (SVM) has been proved to be an efficient approach for forecasting. According to the analysis with support vector machine method, the drawback of determining the parameters only by experts' experience should be improved. After a detailed description of the methodology of SVM and simulated annealing, an improved algorithm was proposed for the automatic optimization of parameters using SVM method. An example has proved that the proposed method can efficiently select the parameters of the SVM method. And by optimizing the parameters, the forecasting accuracy of the max wind velocity increases by 34.45%, which indicates that the new SASVM model improves the forecasting accuracy.
文摘为研究不同容量风力机尾流的相互作用情况,该文通过致动线模型(actuator line model,ALM)耦合大涡模拟(large eddy simulation,LES)的方法对串列布置两台容量不一的水平轴风力机在不同流向间距下的尾流场进行数值模拟,分析尾流场速度分布、涡量分布、频谱特性以及尾涡演变情况。结果表明,随着下游风力机的容量和几何尺寸的增加,尾流区速度波动越大,上下游风力机尾流掺混强度增强,掺混后的涡结构向上偏转程度加剧,使垂向尾流发展更加均匀,湍动能也较大;随着流向间距的增加,下游风力机的尾流受上游风力机轮毂中心涡的卷吸作用减弱,受下叶尖涡和塔筒脱落涡的裹挟输运作用增加。总体来讲,大小容量不同的风力机的尾流掺混能在一定程度上加速尾流的恢复,但是需要一定的发展空间来使其克服下游风力机产生的进一步速度亏损的影响,该文中的发展空间为6~8D。
文摘考虑到山谷气流的复杂性,我们在山地云雾物理研究和人工影响天气作业中,需要更加关注低层风廓线及垂直气流的观测研究。本文针对我国庐山云雾试验站的山谷地形及其与庐山气象站的85 m高度落差特点,利用2019年11、12月云雾试验站测风激光雷达的40~260 m高度风廓线和气象站10 m风的联合观测,分析了山谷低层风廓线特征、垂直运动与水平气流的关系及其影响因素。结果表明:(1)云雾试验站80 m高度与气象站10 m高度的风速和风向相关性较好,该高度的垂直速度和水平风速分别以±0.5 m s^(-1)、2~4 m s^(-1)为主。(2)云雾试验站所处山谷的平均风速随高度递增,白天风速在各高度上均低于夜间;昼夜风速差随高度增大,80 m(40 m)高度的昼夜风速差分别为-1 m s^(-1)(-0.2 m s^(-1))。(3)山谷低层垂直运动的方向主要与山谷开口方向及气流来向有关,与气流强度的关系不大;垂直速率大小与水平风速成正比。如云雾试验站80 m高度偏南风(风向112.5°~247.5°)上升气流占主导,其余风向下沉气流占主导,该关系可延展到260 m高度。(4)山谷低层气流弱风向切变可导致垂直运动分层,反映了山谷地形气流比平原更复杂。
基金Projects(201208430262,201306130031)supported by the China Scholarship Council
文摘In order to improve structure performance of the dish solar concentrator,a three-dimensional model of dish solar concentrator was established based on the high-precision numerical algorithms.And a virtual wind tunnel experiment with constant wind is adopted to investigate the pressure distribution of the reflective surface,velocity distribution of the fluid domain for the dish solar concentrator in different poses and wind speeds distribution.Some results about wind pressure distribution before and after dish solar concentrator surface and wind load velocity distribution in the entire fluid domain had been obtained.In particular,it is necessary to point out that the stiffness at the center of the dish solar concentrator should be relatively raised.The results can provide a theoretical basis for the improvement of solar concentrator dish structure as well as the failure analysis of dish solar concentrator in engineering practice.
