浅水风波波高,波周期分布

通过浅水风波试验，探讨了浅水波高、波周期的分布形式，重点分析了水深因素对波高、波周期分布的影响，给出了浅水波高、波周期分布的表达式，并确定了浅水特征波高间的关系。     

几种疑难心电波形的自动识别方法探讨

本文提出几种疑难心电波形的识别方法,该方法的特点在于将医生读图的经验引入识别过程,设定可能性识别判据,从而显著提高了自动诊断系统对于预激综合症、完全性左、右束支传导阻滞和心肌梗塞等病种的诊断准确性。     

福建东山湾海浪现场观测的统计特征

为分析福建省南部港湾──东山湾的波浪特征,采用S4型压力式方向波浪仪观测获取现场一个月的风浪过程资料,对其进行了统计分析和频谱分析,给出了波高和周期分布,特征波要素与频谱关系,结果表明:实测波高分布与瑞利分布基本相符;波浪谱的显著部分在狭窄的频率内,对应3、5、6、7级风谱峰密度值(m2s)分别为0.084 3、0.372 8、0.941 8、1.837 7,随着风速的增加,谱能也显著地增加,谱曲线下面的总面积增大,谱的显著部分波及的频率范围也扩大,且谱的显著部分沿低频率的方向推移,对应风浪的波高及周期范围增大.     

Nonlinear interactions between gravity waves and background winds

Using the nonlinear propagating gravity waves (GW) model in the two-dimensional compressible atmosphere and the linear GW theory, the process of GW propagation in different background winds, e.g. the direction of the background wind is opposite to (dead wind) or the same as (tail wind) the direction of the horizontal phase velocity of GW, is studied. The results show that the dead wind prolongs the vertical wavelength and accelerates GW propagation. Therefore, GW propagates up to a higher height becomes instable in a short time and eventually induces an inverse jet flow. Then, the vertical wavelength is becoming short due to the nonlinear interactions between GW and the inverse jet flow. The vertical wavelength and group velocity decrease after GW propagates into the tail wind. The initial instable time is delayed. Although most of GW is trapped in the instable region, some of GW propagates above the instable region. Compared with GW propagation in the tail wind, the nonlinear interactions between GW and the dead wind are also strong. In contrast, the linear GW theory predicts that GW can propagate freely in the dead wind. The vertical wavelength simulated by the nonlinear numerical model is different from that predicted by the linear theory greatly after GW propagates into the dead wind.     

高斯束谐振系统对遗迹高频引力波方向的选择效应

高斯束谐振系统为早期宇宙遗留的随机高频引力波的探测开启了一个非常重要的窗口．本文指出,当入射引力波的传播方向与高斯束不同时,高斯束谐振系统产生的一阶扰动光子流将降低几个数量级,即高斯束谐振系统只对沿某一特定方向传播的高频引力波产生响应．因此,高斯束谐振系统对高频引力波的传播方向具有良好的选择效应．     

动力弹塑性分析在桥梁工程中的应用

依据我国《建筑抗震设计规范》(GB50011-2001)和《公路桥梁抗震设计细则》(JTG/T B02-01-2008),以及弹性阶段承载力设计和弹塑性阶段变形验算的两阶段设计理论,使用MIDAS Civil 2006通用有限元程序进行某大桥动力弹塑性抗震分析,并对罕遇地震作用下的结构响应进行了综合评定并概括介绍了塑性铰区域纤维模型的建立方法和桩基础的模拟过程.     

随机波波生流的数值模拟

为了更合适地反映实际海浪的随机性,作者采用随机波折射－绕射模型和波生流模型对近岸海域中的波生流进行数值模拟,探讨不同条件下随机波波生流的流场结构。通过计算发现除地形对随机波波生流有明显影响外,波生流的大小同入射波高及波浪破碎关系密切,其流向特别是离岸流的位置与入射波向有关。     

一种离子温度分布下的测地声模连续谱的参量激发

在离子温度为非均匀的等离子体中漂移波激发测地声模连续谱的过程中,对测地声模固有频率的径向分布函数的不均匀部分取双曲正切函数的情况,研究了漂移波边带模和测地声模连续谱的径向结构以及测地声模增长率.数值结果表明漂移波边带模的径向结构分布图都与简谐振荡都很接近,测地声模连续谱的能量都主要集中在参量激发的共振点附近,而测地声模增长率和泵波振幅的平方成正比.     

冲击回波信号的小波分析研究

利用冲击回波信号的连续小波变换波形特点,精确提取冲击回波信号的纵波和横波波前,大大提高了冲击回波材料弹性模量的测量精度。     

WIND observations of plasma waves inside the magnetic cloud boundary layers

Based on the WIND observational data for the plasma waves from thermal noise receptor （TNR） working on the frequency 4-256 kHz and the solar wind and the magnetic fields, we analyze the plasma wave activities in the 60 magnetic cloud＇s boundary layers （BLs） and find that there are often various plasma wave activities in the BLs, which are different from those in the adjacent solar wind （SW） and the magnetic clouds （MC）. The basic characteristics are that： （1） the enhancement of the Langmuir wave near the electronic plasma frequency （fpe） is a dominant wave activity, which occupies 75% investigated samples; （2） the events enhanced both in the langmuir and ion acustic （f〈fpe） waves are about 60% of investigated samples; （3） broadband, continuous enhancement events in the plasma wave activities were observed in the whole frequency band of TNR, and about 30% of the 60 samples, however, were not observed in the SW and the MC investigated events; （4） although the ratio of the temperatures between the electon and proton, Te/Tp ≤1, the ion caustic wave enhancement activities are still often observed in the BLs, which makes it difficult to explain them by the traditional plasma theory. New results reported in this paper further show that the magnetic cloud＇s BL is an important dynamic structure, which could provide useful diagnosis for understanding the cloud＇s BL physics and could expand a space developing space plasma wave theory.