Influence of Underwater Acoustic Channel on Nonlinear Dynamic Behavior of Chaotic Signal

在水声通信领域，由于水声信道是一个十分复杂的时变、空变、频变信道，信号在信道中的传输存在严重的传播损失和多径干扰，给水声通信和信号处理带来极大的困难。因此，滤波技术在水声信号处理中有着十分重要的应用。 由于海洋水声信道的复杂性，造成水声信号的高度复杂性以及高度非平稳性，水声信号呈现出强烈的非线性特征。因此，在水声信号处理研究中，常见的线性处理方法局限性较大，需要引入相应的非线性理论和方法。 混沌应用于水声领域，主要集中在信号的特征提取、检测和识别等方面。对于混沌信号在水声信道传输中，其自身动力学特性的变化的研究较少。本文运用非线性分析方法，研究了混沌信号经过滤波以及水声信道传输后，其非线性...In the field of underwater acoustic communication, as acoustic channel is a complicated space-time-frequency varying channel, signal transmission inevitably exists serious loss and multipath effects, which brings great difficulty to underwater acoustic communication and signal processing. The complexity of underwater acoustic channel causes highly complex and non-stationary acoustic signals whic...学位：理学硕士院系专业：海洋与环境学院海洋学系_海洋物理学号：3112008115145

Influence of Chaotic IIR Filter on Nonlinear Dynamic Characteristic of Underwater Acoustic Signal

本文探讨了混沌滤波器在水声信号处理中的一种新的应用.混沌蔡氏电路产生的信号进行频带调制和高通IIr滤波后,由水声换能器发射并经过水池传播和接收.实验结果表明混沌滤波器实现了频带搬移,且接收到的水声信号具有与原始的混沌发射信号相似的宽频带特性.进一步,运用非线性动力学方法对原始混沌电路信号和接收水声信号进行时间序列分析比较.发现接收的水声信号具有比发射的原始混沌信号更为不规则的重建相空间和更高的分形维数.混沌滤波器运用于水声信道提高了接收信号的非线性复杂特性.A new application of chaotic filter in underwater acoustic signal processing is described.After frequency modulation and high-pass IIR filtering,the chaotic signal generated by the Chua's circuit was transmitted through a underwater sound channel.The received acoustic signal shows similar frequency band characteristic with chaotic circuit.Furthermore,nonlinear dynamic analysis is applied to compare the underwater acoustic signal and the original circuit signals.The results show that the acoustic signal has more irregular phase space and higher fractal dimension than chaotic circuit signals.Chaotic filter increases the complexity of the underwater signal

Validity and Reliability of the Chinese Version of the Early Signs Scale of Schizophrenia

目的：检验精神分裂症复发先兆量表（early signs scale, ESS）中文版（ESS-C）的效度和信度。方法：应用ESS-C对200例社区慢性精神分裂症患者（社区稳定组）和60例复发住院患者（复发入院组）进行评估,2周后抽取30例社区患者重测。结果：验证性因素分析表明原量表的四因子结构拟合指数为CFI=0.83,TLI=0.82,SRMR=0.056,RMSEA=0.084。各维度的因子负荷范围为焦虑0.545-0.753;抑郁/退缩0.563-0.760;失控/兴奋0.462-0.757;初始的精神病性表现0.566-0.790。ESS-C的内容效度（CVI）为0.92,所有条目的CVI值均在0.80-1.00范围内。组间比较Kolmogorov-Smirnov检验结果显示复发入院组的量表总分显著高于社区稳定组。总量表内部一致性Cronbachα系数为0.966,各因子Cronbachα系数为0.813-0.922;总量表、各因子的重测信度在0.724-0.921之间。结论：最终形成的ESS-C量表内容效度、效标效度及信度良好,结构效度可接受但不够理想

中国脑血管病临床管理指南（第2版）（节选）——第4章 缺血性脑血管病临床管理推荐意见 Chinese Stroke Association Guidelines for Clinical Management of Cerebrovascular Diseases (Second Edition) (Excerpt)——Chapter Four Clinical Management of Ischaemic Cerebrovascular Diseases

我国的卒中发病率仍在持续上升，每年新发病例占全球的四分之一。在我国40岁及以上的人群中，缺血性卒中约占所有卒中类型的86.8%。自2019年中国脑血管病临床管理指南发布以来，缺血性卒中急性期再灌注治疗及二级预防抗血小板治疗等领域取得了多项进展。本指南就缺血性卒中急性期评估及诊断、再灌注治疗、抗血小板治疗、其他治疗、常规支持治疗及并发症管理、病因及发病机制的早期评估和诊断、针对病因和发病机制的干预、危险因素管理及长期干预更新推荐意见。 Abstract: The incidence of stroke in the Chinese population is still on the rise, accounting for nearly one-fourth of the global annual stroke cases. Among adults aged 40 or above in China, ischaemic stroke (IS) accounted for approximately 86.8% of all strokes. Since the publication of the 2019 Chinese Stroke Association guidelines, notable advancements have emerged in acute-phase reperfusion therapy and antiplatelet treatments for secondary prevention in IS. The guidelines have provided updated recommendations on evaluation and diagnosis of acute phase of ischaemic stroke, reperfusion therapy, antiplatelet therapy, other treatments in the acute phase, general supportive treatment and complications management, early evaluation and diagnosis of aetiology and pathogenesis, interventions targeting aetiology and pathogenesis, risk factors management, and long-term intervention