Results 21 to 30 of about 13,317 (119)
Two decades of changes in the global network of illegal wildlife trade
Abstract Understanding how illegal wildlife trade (IWT) has changed over time is fundamental for biodiversity conservation; however, knowledge of the network remains limited. We used TRAFFIC's IWT dataset, legal trade data from the CITES legal wildlife trade database as a benchmark, and network analysis to identify changes in IWT from 2000 to 2022. The
J. H. Tow +5 more
wiley +1 more source
ABSTRACT The realization of bifunctional perovskite devices integrating photovoltaic (PV) and light‐emitting diode (LED) capabilities requires precisely controlled grain architectures to facilitate dual carrier transport pathways. In this work, sulfaguanidine (SG) molecules were introduced into the perovskite solution to reconstruct the crystallization
Jiong Li +7 more
wiley +1 more source
短路电流直流分量含量对断路器开断能力有很大影响,然而对直流分量的计算至今缺乏简单实用的方法。分析短路电流直流分量产生原理及其衰减特性,结合电力网络数学模型的特点,提出了基于转移阻抗理论的短路电流直流分量实用计算方法:将电力系统复杂网络近似简化为以短路点为中心的辐射形网络,求出各发电机所提供短路电流直流分量及其衰减情况,最终对所有分支短路电流直流分量求和近似计算出故障点短路电流直流分量。通过实用计算方案与EMTP仿真计算以及故障录波的对比分析,验证了该方法的准确性。
张旭航 +5 more
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ABSTRACT Chemically self‐charging aqueous zinc‐ion batteries (AZIBs) have emerged as promising candidates for energy storage technologies owing to their environmental autonomy and structural simplicity. Nonetheless, the self‐charging performance is significantly compromised by the limited potential difference between cathodes and oxygen, as well as the
Yan Wang +5 more
wiley +1 more source
容量试验中短路电流直流分量的大小直接影响电流过零点的di/dt与TRV,对直流分量的精确控制直接关系到试验质量与效率。容量实验室通常控制3台独立的合闸开关分别进行选相合闸以产生满足要求的直流分量。文中运用理论分析方法找出了产生完全对称短路电流和最大非对称短路电流的选相方法,并对一种含有Y/△变压器的回路进行了分析,总结了根据电流波形判断合闸开关关合顺序的方法。
张晋波 +4 more
doaj
ABSTRACT Objective To investigate whether combining abnormal morphological features observed on ultrasound in live pregnancies that ended in a first‐trimester miscarriage can predict an abnormal karyotype. Methods This retrospective observational cohort study was conducted at the early‐pregnancy assessment unit at University College London Hospital ...
T. Setty +5 more
wiley +1 more source
直流分压器是特高压直流输电系统中不可缺少的主设备,其采集数据的准确性对电网的安全稳定运行至关重要。基于直流分压器的工作原理,分析致使直流分压器分压比变化的主要因素,通过数学公式直观的诠释分压比的不确定性,然后在研究分压比不确定性的基础上构建直流分压器校准分析计算模型,并试验证明了该模型对站用±800 kV直流分压器的校准水平高达10-510-6量级,大幅度提升了直流分压器量值测量的准确度。
王奇 +4 more
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基于经验傅里叶分解的混合式高压直流断路器耗能支路故障检测方法研究 [PDF]
为实现更强的能量耗散能力,混合式高压直流断路器的耗能支路需串并联大量金属氧化物压敏电阻(metal oxide varistor,MOV),耗能支路的可靠性将直接影响混合式高压直流断路器的可靠性。但是,现有的耗能支路故障检测方法并不能适应整个能量耗散阶段。为此,提出一种基于经验傅里叶分解的混合式高压直流断路器耗能支路故障检测方法,具体为:首先是信号预处理,对耗能支路每个子模块的分支电流进行归一化和一阶差分计算来获取分析电流;然后是故障特征提取,利用经验傅里叶分解(empirical Fourier ...
彭兆伟 +5 more
doaj +1 more source
ABSTRACT Photocatalytic molecular oxygen (O2) activation provides a sustainable approach to produce singlet oxygen (1O2) for organic contaminants detoxification. However, the charge carriers‐involved pathway usually suffers from unsatisfactory 1O2 production efficiency owing to energy loss caused by photogenerated hole‐mediated superoxide species (•O2−
Yan‐Biao Shi +8 more
wiley +1 more source
采用抛物线拟合方法计算大容量试验短路电流波形的峰值和对应的时间坐标。理论证明短路电流波形上相邻两峰值的时间坐标中点的电流值近似等于此时的直流分量值,并据此给出波形的直流时间常数、交流(基波)分量有效值和直流分量百分数的算法。使用STL提供的标准短路电流波形,对文中算法和现有算法进行了对比测试。测试结果验证了该算法的准确性,同时表明,仅使用3个峰值点并未显著降低文中算法在计算交流分量恒定的短路电流波形参数时的准确度。通过计算直流时间常数不同 ...
周小猛 +4 more
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