针对风火打捆(wind-thermal-bundled,WTB)系统在受到干扰时可能由于阻尼不足而出现的低频振荡现象以及较高的网损会导致运行成本的增加和阻碍“双碳”目标实现的问题,提出了一种电力系统稳定器(power system stabilizer,PSS)与统一潮流...针对风火打捆(wind-thermal-bundled,WTB)系统在受到干扰时可能由于阻尼不足而出现的低频振荡现象以及较高的网损会导致运行成本的增加和阻碍“双碳”目标实现的问题,提出了一种电力系统稳定器(power system stabilizer,PSS)与统一潮流控制器(unified power flow controller,UPFC)附加功率振荡阻尼控制器(power oscillation damping,POD)参数和UPFC安装位置协调优化策略方法。首先,基于Matlab构建了风火打捆外送系统和控制器模型。然后,利用多目标樽海鞘优化算法(multi-objective salp swarm algorithm,MSSA),将协调优化问题转化为多目标优化问题。目标函数设计中考虑了UPFC装置的调节特性。最后,采用IEEE 4机2区系统和16机5区系统进行多种工况下的仿真。仿真结果显示,协调优化后的控制器可以提高系统阻尼,维持发电机转速的稳定,抑制低频振荡引起的系统有功、电压等的波动,同时降低了系统的有功网损,提高了系统稳定性和运行经济性。MSSA在工程问题上的应用得到了补充。展开更多
针对当前油浸式电力变压器绕组瞬态温升仿真中,采用固定时间步长效率低的问题,提出一种混合变步长方法。首先,采用初始解优化算法,有效减少计算过程中方程的迭代次数;其次,结合本征正交分解算法(properorthogonal decomposition,POD),...针对当前油浸式电力变压器绕组瞬态温升仿真中,采用固定时间步长效率低的问题,提出一种混合变步长方法。首先,采用初始解优化算法,有效减少计算过程中方程的迭代次数;其次,结合本征正交分解算法(properorthogonal decomposition,POD),改善大规模有限元方程组存在的阶数过高、条件数过大的问题,提高了方程的求解效率和数值稳定性;第三,提出自适应(adaptivetimestepping,ATS)-启发式(heuristic time stepping,HTS)混合变步长算法,通过对时间步长的自适应与启发式调整,有效解决瞬态计算中计算效率与计算精度的对立问题;最后,建立油浸式电力变压器绕组二维单分区分匝的流热耦合仿真模型,以验证所提算法的正确性与高效性。数值计算结果表明:在流场中,与固定步长的计算结果相比,混合变步长算法的误差小于0.46%,计算效率提升了18.45倍;在温度场中,与固定步长的计算结果相比,所提算法的误差小于0.04%,计算效率提升了6倍。同时,通过与传统变步长算法的计算结果对比,说明所提混合变步长算法在计算精度、计算效率及变步长效果方面均具有一定优势。此外,还探讨混合变步长计算中,不同的参数设置对瞬态计算结果及状态变化过程的影响,为其工程应用奠定了一定基础。展开更多
Peanut (Arachis hypogaea L.) is a highly nutritious food that is an excellent source of protein and is associated with increased coronary health, lower risk of type-2 diabetes, lower risk of breast cancer and a health...Peanut (Arachis hypogaea L.) is a highly nutritious food that is an excellent source of protein and is associated with increased coronary health, lower risk of type-2 diabetes, lower risk of breast cancer and a healthy profile of inflammatory biomarkers. The domestic demand for organic peanuts has significantly increased, requiring new breeding efforts to develop peanut varieties adapted to the organic farming system. The use of unmanned aerial system (UAS) has gained scientific attention because of the ability to generate high-throughput phenotypic data. However, it has not been fully investigated for phenotyping agronomic traits of organic peanuts. Peanuts are beneficial for cardio system protection and are widely used. Within the U.S., peanuts are grown in 11 states on roughly 600,000 hectares and averaging 4500 kg/ha. This study’s objective was to test the accuracy of UAS data in the phenotyping pod and seed yield of organic peanuts. UAS data was collected from a field plot with 20 Spanish peanut breeding lines on July 07, 2021 and September 27, 2021. The study was a randomized complete block design (RCBD) with 3 blocks. Twenty-five vegetation indices (VIs) were calculated. The analysis of variance showed significant genotypic effects on all 25 vegetation indices for both flights (p < 0.05). The vegetation index Red edge (RE) from the first flight was the most significantly correlated with both pod (r = 0.44) and seed yield (r = 0.64). These results can be used to further advance organic peanut breeding efforts with high-throughput data collection.展开更多
飞机结构损伤导波在线监测技术作为一种新颖的无损检测手段,为了真正实现该技术在结构运营维护过程中的视情维护,必须明确其结构损伤检出概率(probability of detection,POD),以指导结构检查维修方案的制定。提出了一种基于信号响应分...飞机结构损伤导波在线监测技术作为一种新颖的无损检测手段,为了真正实现该技术在结构运营维护过程中的视情维护,必须明确其结构损伤检出概率(probability of detection,POD),以指导结构检查维修方案的制定。提出了一种基于信号响应分析模型的结构损伤导波POD计算方法,该方法通过构建在线导波监测信号的损伤指数与裂纹长度间的对应关系,得到结构损伤POD的统计计算模型,并分析了拟合参数的不确定性对计算模型的影响,构建了不同置信度下的导波POD计算模型。通过开展金属开孔和搭接结构疲劳裂纹导波监测试验,验证了该方法的有效性。试验结果表明,损伤指数类型、对应关系拟合函数和传感器监测方案均对结构损伤导波POD具有影响,且在95%置信度90%POD下金属开孔和搭接结构的可检裂纹长度分别约为2.6 mm和9.5 mm。展开更多
文摘针对当前油浸式电力变压器绕组瞬态温升仿真中,采用固定时间步长效率低的问题,提出一种混合变步长方法。首先,采用初始解优化算法,有效减少计算过程中方程的迭代次数;其次,结合本征正交分解算法(properorthogonal decomposition,POD),改善大规模有限元方程组存在的阶数过高、条件数过大的问题,提高了方程的求解效率和数值稳定性;第三,提出自适应(adaptivetimestepping,ATS)-启发式(heuristic time stepping,HTS)混合变步长算法,通过对时间步长的自适应与启发式调整,有效解决瞬态计算中计算效率与计算精度的对立问题;最后,建立油浸式电力变压器绕组二维单分区分匝的流热耦合仿真模型,以验证所提算法的正确性与高效性。数值计算结果表明:在流场中,与固定步长的计算结果相比,混合变步长算法的误差小于0.46%,计算效率提升了18.45倍;在温度场中,与固定步长的计算结果相比,所提算法的误差小于0.04%,计算效率提升了6倍。同时,通过与传统变步长算法的计算结果对比,说明所提混合变步长算法在计算精度、计算效率及变步长效果方面均具有一定优势。此外,还探讨混合变步长计算中,不同的参数设置对瞬态计算结果及状态变化过程的影响,为其工程应用奠定了一定基础。
基金supported in part by the National Natural Science Foundation of China(Nos.12172372,12132019)the National Major Science and Technology Projects(No.J2019-III-0010-0054).
文摘掌握结冰云雾参数的分布对于飞机结冰分析具有重要意义。为了获得这些参数,传统的高保真数值模拟技术计算效率低,难以应用于需要实时评估结冰的工程场景。为了克服这一困难,通过本征正交分解(Proper orthogonal decomposion,POD)方法与Kriging技术相结合,提出了一种非侵入式结冰云雾参数计算代理模型。该模型以4个飞行参数和2个云参数作为输入变量,模型输出为液体水含量(Liquid water content,LWC)和液滴收集系数。采用准三维NACA0012翼型验证了模型的准确性和计算效率。4个测试案例的数值结果表明:POD_Kriging模型准确、有效。相比于经典的FENSAP‐ICE软件,所开发的代理模型能够更有效的得到结冰云雾场。
文摘Peanut (Arachis hypogaea L.) is a highly nutritious food that is an excellent source of protein and is associated with increased coronary health, lower risk of type-2 diabetes, lower risk of breast cancer and a healthy profile of inflammatory biomarkers. The domestic demand for organic peanuts has significantly increased, requiring new breeding efforts to develop peanut varieties adapted to the organic farming system. The use of unmanned aerial system (UAS) has gained scientific attention because of the ability to generate high-throughput phenotypic data. However, it has not been fully investigated for phenotyping agronomic traits of organic peanuts. Peanuts are beneficial for cardio system protection and are widely used. Within the U.S., peanuts are grown in 11 states on roughly 600,000 hectares and averaging 4500 kg/ha. This study’s objective was to test the accuracy of UAS data in the phenotyping pod and seed yield of organic peanuts. UAS data was collected from a field plot with 20 Spanish peanut breeding lines on July 07, 2021 and September 27, 2021. The study was a randomized complete block design (RCBD) with 3 blocks. Twenty-five vegetation indices (VIs) were calculated. The analysis of variance showed significant genotypic effects on all 25 vegetation indices for both flights (p < 0.05). The vegetation index Red edge (RE) from the first flight was the most significantly correlated with both pod (r = 0.44) and seed yield (r = 0.64). These results can be used to further advance organic peanut breeding efforts with high-throughput data collection.
文摘飞机结构损伤导波在线监测技术作为一种新颖的无损检测手段,为了真正实现该技术在结构运营维护过程中的视情维护,必须明确其结构损伤检出概率(probability of detection,POD),以指导结构检查维修方案的制定。提出了一种基于信号响应分析模型的结构损伤导波POD计算方法,该方法通过构建在线导波监测信号的损伤指数与裂纹长度间的对应关系,得到结构损伤POD的统计计算模型,并分析了拟合参数的不确定性对计算模型的影响,构建了不同置信度下的导波POD计算模型。通过开展金属开孔和搭接结构疲劳裂纹导波监测试验,验证了该方法的有效性。试验结果表明,损伤指数类型、对应关系拟合函数和传感器监测方案均对结构损伤导波POD具有影响,且在95%置信度90%POD下金属开孔和搭接结构的可检裂纹长度分别约为2.6 mm和9.5 mm。
