Results 61 to 70 of about 16,458 (194)
Gaoya dianqi, 2019 随着电网系统的快速发展,大容量、高电压电力变压器不断增多,其振动与噪声对设备自身及周边居民的健康造成的影响日益凸显,因此变压器振动与噪声及其控制受到了国内外学者的广泛关注。文中从变压器振动噪声机理、特性、影响因素以及控制措施等方面对国内外研究进展进行综述。分析了硅钢片的磁致伸缩特性及Maxwell应力特性,得出铁心振动噪声的主要来源及数学模型;根据绕组磁场分布及受力分布,分析了绕组轴向及幅向振动特性及数学模型;总结了冷却设备等部件的振动特性。从振动产生、传递到噪声辐射等过程分析了变压器传播特性。从激励 ...
汲胜昌, 师愉航, 张凡, 陆伟锋
doaj
Dynamic Analysis of Dry-jointed Structure—Case Study on Yingxian Wood Pagoda of China [PDF]
, 2017 常见的干架结构包括传统的干砌或弱浆砌砖石结构、中国古建筑木结构等空间多体干连接组合结构体系。该类结构由多个块体构件按照一定规则简支叠置，构件间不采用粘结材料形成拉结，借助自重及摩擦力抵抗侧向力。目前对干架结构的研究较少，且已有的对干架结构的数值模拟研究多基于连续杆系结构思想，与实际差异较大。本文从干架结构的特点出发，采用多体动力学及离散单元法对简单的块体干架结构进行分析，进而对中国古代建造的干架结构的典型——应县木塔进行探索。 运用理论力学方法及UDEC离散元软件建模分析，得出了在平面干连接接触 ...
刘星帆
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A Multifunctional Reducing Molecular Dopant for 16% Efficient Tin Perovskite Solar Cells
Rare Metals, EarlyView.ABSTRACT Although lead‐based photovoltaics have seen remarkable progress, tin‐based perovskite solar cells (Sn‐PSCs) continue to face challenges due to their limited power conversion efficiency and insufficient operational stability. The primary cause of this performance gap is the susceptibility of Sn2+ to oxidation, which promotes rapid defect ...
Xianyong Zhou +12 more
wiley +1 more source
Gaoya dianqi, 2015 碟簧作为储能元件是高压断路器用液压操动机构的重要核心部件,其优点是能在很小变形的条件下,承受范围变化很大的载荷。储能碟簧的可靠性直接影响着液压操动机构及高压断路器的整体可靠性。笔者通过碟簧力学特性分析、碟簧应力计算、碟簧力学特性曲线试验、碟簧力学时效性试验及单片碟簧断裂后对整组碟簧性能的影响试验,验证了某高压断路器用液压操动机构储能碟簧的可靠性。
周仙娥 +3 more
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, 2001 升力体气动布局，由于其良好的高超声速气动特性、有效的内部空间和有益的防热特性，越来越受到气动工作者的重视，该文应用张涵信院士的NND格式思想，用数值模拟的方法对类似于美国X-33的升力体外形进行了气动力、气动热研究。特别是在粘性项的离散和表面热流率的计算中应用了散度和梯度的积分定义，避免了数值计算的奇异性，保证了通量守恒，提高了计算效率。结果表明气动热计算结果与美国同类飞行器结果接近 ...
刘宏 +4 more
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Multi-degree-of-freedom hydrodynamic performance study of finned floats [PDF]
ObjectiveTo optimize the energy capture efficiency of a rocker-type wave energy converter, the effects of the platform pillar wave diversion scheme and shape of finned floats on energy capture are studied.MethodsFirst, a hydrodynamic model of float ...
Biao ZHANG +5 more
core +1 more source
Wildlife Letters, EarlyView.This review summarizes the status of musk deer in China, highlighting severe population declines due to illegal hunting and habitat loss, and proposes integrated conservation strategies including habitat protection, captive breeding, and law enforcement to support the recovery and sustainable management of this ecologically and economically important ...
Feng Jiang +8 more
wiley +1 more source
Gaoya dianqi, 2005 真空断路器的动触头运动特性对其开断能力和寿命影响很大。介绍了一种控制分闸运动特性的方法,通过控制永磁机构的分、合闸线圈的接入时间,控制分闸的的运动特性。在实验室进行了试验,验证了该方法的可行性。
黄瑜珑 +3 more
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Shuitu Baochi Xuebao, 2023 粗糙度是影响坡面流水动力特性的关键因子,为探究渐变粗糙度影响下坡面流水力特性,采用粒子图像测速技术(particle image velocimetry, PIV)观测并分析3组流量下渐变粗糙床面下坡面流的流速轮廓线、紊动强度、雷诺应力和壁面切应力的变化规律。结果表明:(1)流速随粗糙度增加而减小;拟合无量纲流速得到流速分布对数公式,粗糙度增大与拟合常数A成反比,与积分系数B成正比。(2)渐变地表粗糙度流向紊动强度与光滑床面坡面流变化趋势相似。流向紊动强度随相对水深的增大而减小。随着粗糙度增大 ...
谷方正 +4 more
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Dynamic characteristics and damage model of freezing thawing red sandstone under impact load [PDF]
To study the dynamic mechanical properties and damage evolution characteristics of freeze-thaw rocks under impact loads, 0, 15, 30, 45, and 60 freeze-thaw cycle tests and dynamic impact tests were conducted on red sandstone in cold regions.
Huiming ZENG +5 more
core +1 more source