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Dizhen xuebao, 2022 地震动合成方法的应用前景与其所能表达的有效频带范围紧密相关。本文研究基于频率波数域格林函数的地震动合成方法（FK法），分析频带范围的关键影响要素及处理措施。在介绍计算原理的基础上，概括FK法合成地震动的主要影响要素，分析地壳速度模型对子源地震矩、破裂时间和传播时间的影响。随后，分析格林函数传播宽频带地震波的能力，提出格林函数计算中的频带影响参数的建议值。为分析FK法的震源模型辐射宽频带地震波的能力，重点考察控制子源错动过程的震源时间函数和上升时间。研究认为，FK法具有合成宽频带地震动的能力 ...
Zelin Cao +3 more
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基于小波变换的2013年芦山MS7.0地震前姑咱台钻孔应变异常时频分析
Dizhen xuebao, 2019 2013年4月20日芦山MS7.0地震前，四川省姑咱台四分量YRY-4型钻孔应变仪记录到显著的高频应变畸变信号。为了避免该畸变信号的高频部分在时频演化过程中发生频率混叠现象，同时便于讨论同一研究频段内震前更早记录到的弱应变异常时段与显著应变异常时段的相关性，本文对2012年1月1日至2013年4月20日期间姑咱台的钻孔应变数据进行了时频分析，并使用时域分段的小波变换方法，在局部时频谱中提取了应变异常，分析了各应变异常的频率相关性。结果表明，研究频段内存在两个峰值频率 ...
Weichen Zhang +4 more
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Conservation Biology, EarlyView.Abstract Knowledge of species distributions is essential for informing policies on nature conservation and restoration. However, updating them on a regular basis and doing so in a harmonized manner at the international level is difficult. The European Bird Census Council integrated national monitoring data covering 5 years to update farmland bird ...
Sergi Herrando +54 more
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Estimating the total mortality of seabirds following a marine heat wave
Conservation Biology, EarlyView.Abstract Marine heat waves detrimentally affect a range of marine species, including seabirds, and are increasing in frequency and severity. When thousands of dead seabirds wash up on beaches, the public becomes concerned. However, the number of dead birds recorded on beaches is only a fraction of the total mortality; most birds perish at sea.
Jennifer L. Lavers +3 more
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Uncovering correlates of decline and critical refuges for a threatened terrestrial mammal
Conservation Biology, EarlyView.Abstract Globally, the geographic ranges of numerous species are contracting. Identifying spatiotemporal patterns of threat impact can illuminate why species decline in some parts of their range but persist in others. We developed a correlative approach to identify species’ response thresholds and locate ecological refuge areas associated with ...
Natalya M. Maitz +5 more
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Institutional lessons from the Nordic management model
Conservation Biology, EarlyView.Abstract To improve wildlife management outcomes, in terms of reaching management goals and increasing legitimacy, Nordic countries have developed institutional systems involving stakeholders that aim for a more inclusive and participatory model.
Jens Nilsson +2 more
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International Journal of Applied Linguistics, EarlyView.ABSTRACT This study investigates how the learner‐related factors of language dominance, encompassing language history, proficiency, use, and attitude, modulate congruency effects in multi‐word unit (MWU) processing among early bilinguals. Seventy Cantonese–Putonghua bilinguals completed lexical decision tasks measuring reaction time and accuracy for ...
Mingjia Cai, Yuan Liang
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, 2003 介绍了典型的时频分析方法及所研发的虚拟式多功能时频分析系统。该仪器系统功能十分强大,主要包括:零相位数字滤波、短时付氏变换、多分辨时频分析、魏格纳分布、乔伊威廉斯分布、小波和小波包阈值滤波、二进小波及小波包正交分解、连续小波变换等。文中逐一介绍各主要功能的基本原理。给出了仪器的开发、设计、仿真及其应用实例。值得一提的是,在分析极大极小尺度共存信号时,作者所提出的多分辨时频分析方法比其它经典时频分析方法有明显的优势。国家863子项目(2002AA842180-1);; 集美大学科研启动基金 ...
纪跃波, 郭隐彪
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, 1981 <正> 一、引言时域法分析线性网络、放大器、晶体管、光纤和光电器件的频带宽度是一种习用的方法。然而相关文献很少介绍时域法中所引用公式的来龙去脉,因而容易含混不清甚至违背了限制条件,常被误用。本文将推导出时域法中的主要公式,阐明它们的物理概念以及提供它们的应用条件,以期达到正确运用的目的。这里主要以光电器件为例,其它场合也可沿用。时域法分析带宽的实质是:观察和记录电路或器件对快速前后沿脉冲的时间响应 ...
罗红, 刘其源
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基于振动信号EMD-HT时频分析的变压器有载分接开关故障诊断
Gaoya dianqi, 2012 把一列时间序列数据通过经验模态分解（empirical mode decomposition,EMD）为本征模态函数组（intrinsic mode function,IMF）,然后进行希尔伯特变换（hilbert transformation,HT）得到频谱的信号时频分析方法引用到变压器有载分接开关切换机构的振动信号分析领域。笔者介绍了该方法的理论和算法。首先采用仿真信号对该方法进行仿真验证,然后把一实测的有载分接开关故障振动信号进行基于EMD-HT方法的时频分析。通过仿真和实例信号分析结果说明 ...
张惠峰 +4 more
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