Results 31 to 40 of about 34,473 (149)
四川大学学报. 自然科学版, 1993 为各种开关结构的直流功率变换器提出一种新的、统一的建模方法。该法的基本途径是:将变换器中的全部时变开关集中在一个子网络里,用时间平均技术及脉冲响应法,导出开关子网络的低频等效模型,与变换器的其它部分连结起来,构成了可用SPICE作辅助分析的全等效电路。该方法能够在计算机辅助下,对开关变换器作瞬态分析、输人-输出传递函数的频响分析(纹波抑制特性)、控制信号占空比与输出的交流分析。给出了分析实例。
倪治中, 余伟萍
doaj
The Making of the Right to Food: Tracing Food Policy Conflict and Negotiated Outcomes in Colombia
World Food Policy, Volume 12, Issue 2, November 2026.ABSTRACT The 2016 Peace Agreement between the Colombian Government and the FARC guerrilla group marked a historic step toward ending more than five decades of armed conflict. It also reshaped national food policy with lasting implications. During the negotiations, deep ideological divisions emerged between food sovereignty and food security, and these ...
Felipe Roa‐Clavijo
wiley +1 more source
Jianzhu Gangjiegou Jinzhan为揭示偏心竖向荷载作用下薄壁箱梁的畸变，基于能量变分原理和箱梁各板件的静力平衡分析，给出优化后箱梁畸变研究的3种方法。推导出各方法研究梯形截面箱梁畸变解析计算式的普遍形式，得到相应的四阶畸变控制微分方程。对各畸变研究方法采用典型数值算例进行验证，研究结果表明：优化后的各畸变研究方法计算的畸变翘曲正应力值与文献数值相差很小，各方法之间误差最大不超过5.39%，方法2和方法3计算结果误差很小可忽略；各方法计算的矩形截面箱梁的畸变扇性坐标值均相等，梯形截面箱梁的畸变扇性坐标值则不同 ...
王兆南, 张元海
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Gaoya dianqi, 2019 电力变压器是实现电压变换和电能分配的重要电力设备。针对变压器机械故障,振动分析法具备很强的科学性和可行性。文中搭建了基于振动传感阵列的变压器振动测试系统,研究了单相变压器油箱表面振动分布,分别测量绕组在正常状态和故障状态下的油箱振动云图,提取振动云图的方向梯度直方图（HOG）特征,选择支持向量机（SVM）为学习训练方法,形成二类分类器,分辨变压器绕组的正常状态与故障状态。最终提出基于振动云图HOG和SVM的变压器绕组松动故障诊断方法,实验验证该方法有很高的识别率。
朱梓倩 +4 more
doaj
Policy &Internet, Volume 18, Issue 3, September 2026.ABSTRACT Democratic innovations increasingly take place online, yet little is known about how online citizen participation affects perceived legitimacy compared to in‐person formats. This study presents findings from a preregistered vignette experiment conducted in Spain and Switzerland.
Valeria Vuk
wiley +1 more source
World Medical &Health Policy, Volume 18, Issue 3, September 2026.ABSTRACT Confrontational violence still puts catastrophic burdens on children, with 2024 being the highest recorded levels of displacement, malnutrition, injury, and deprivation in contemporary humanitarian history. Children's surgical care is still grossly underrepresented in health responses worldwide in the prevention of avoidable deaths and long ...
Gaurav Chanderprakash Mittal +4 more
wiley +1 more source
Gaoya dianqi, 2005 利用基于边单元的有限元法,对一台200km/h高速电力机车主变压器的油箱损耗进行了三维有限元分析和计算。由于电力机车主变压器是高漏抗,多绕组变压器,经试验（采用放大法）得到该台变压器油箱损耗为31.245kW,使用FEM二维有限元分析法计算结果为45.791kW,而采用三维有限元分析法计算结果为30.478kW。从而表明,采用三维有限元分析能够更加准确地计算主变压器油箱的涡流分布和杂散损耗,为其采取有效的屏蔽措施提供了更加可靠的科学依据。
李季, 罗隆福, 许加柱
doaj
Cutting Through the State: Examining Voter Alignment With Milei's Agenda and His Chainsaw Plan
Latin American Policy, Volume 17, Issue 3, September 2026.ABSTRACT Argentina's political landscape experienced a major shift with the unexpected election of Javier Milei as President. Known for his radical right‐wing stance, Milei has pledged to drastically minimize the state's role, proposing a public spending cut of 14% of the gross domestic product.
Giada Pasquettaz, Franco Bastias
wiley +1 more source
四川大学学报. 自然科学版, 2015 为进一步提高无线传感器网络节点跟踪定位精度降低能耗,提出一种多目标拥挤度差分优化的贝叶斯量化变分滤波预估WSN跟踪定位算法.首先,针对定位问题,采用贝叶斯量化变分滤波方法对目标下一位置区域进行预测,利用量化变分滤波方式选取合适的定位参与节点,并设计了量化变分滤波的多目标参数优化模型.其次,针对传统多目标优化算法寻优精度不高的问题,设计了基于种群个体拥挤度状况的多目标差分进化算法,对量化变分滤波算法参数进行优化,实现了滤波参数的多目标优化.最后,通过实验仿真表明,该算法能够有效实现目标节点的跟踪定位 ...
张睿敏, 陈钟, 李晓斌
doaj
Rare Metals, Volume 45, Issue 8, August 2026.ABSTRACT The electrocatalytic co‐reduction of CO2 and nitrate (NO3− ${\text{NO}}_{3}^{-}$) to synthesize urea presents a sustainable alternative to traditional industrial processes, yet its efficiency is fundamentally limited by the kinetically mismatched activation and coupling of CO2 and NO3− ${\text{NO}}_{3}^{-}$.
Jiayu Liu +9 more
wiley +1 more source