毫秒激光致铝熔融液体准稳态喷溅的模型

通过对毫秒激光致铝(Al)熔融液体喷溅过程中 热通量的研究,建立了熔液在轴对称坐标下形成准稳态 喷溅的运动模型;进而通过解析和数值计算相结合的方法,得到了熔液准稳态喷溅过程中靶 材的中心点温 度、熔液表面的流动速率、熔池中心点的下降速度以及熔液喷溅后熔池的形貌。计算得到的 熔池中心点下 降速度随脉冲激光作用时间的增加而减小,熔液表面流动速率在准稳态喷溅时随熔池半径的 增加而增大。 计算得到的熔池形貌与实验结果相吻合,继而分析了毫秒激光致Al熔液准稳态喷溅时熔池中 心点温度和气 化区域半径随作用激光功率密度的变化关系。随作用激光功率密度的增加,更多的激光能量 转化为靶材的 内能,从而增加了熔液准稳态喷溅时熔池中心点的温度和气化区域半径。     

基于气动新模型的大跨度桥梁频域抖振分析

提出采用准定常气动刚度与基于试验的非定常气动阻尼进行气动修正的大跨度桥梁抖振计算新模型。桥梁节段模型风洞试验表明,气动新模型能相对更准确地描述桥梁结构的气动刚度与气动阻尼特性。以东海大桥的风致抖振响应为例,对气动新模型与传统Scanlan颤抖振模型的分析结果进行了对比研究。计算结果与风洞试验表明,气动新模型具有良好的计算精度与明确的物理意义。     

内旁通式磁流变阻尼器及其准静态流动分析

基于磁流变阻尼器的3种工作模式,本文提出内旁通式磁流变阻尼器工作模式,并对其进行了准静态流动分析.内旁通式磁流变阻尼器由内、外两通道组成,其中内通道受外加磁场的控制,而外通道则处于常通状态.内旁通式阻尼器有助于克服活塞换向时产生的运动空程现象,并简化磁流变阻尼器的设计.     

Transient Thermal Characteristics of the Convecting Solar Pond with the Semi-Transparent Multilayer Surface Insulating System

A concept of the convecting solar pond with the multilayer surface insulating system which is transparent to solar radiation but opaque to infrared radiation is proposed, and its transient thermal characteristics are discussed by solving time-dependent energy equations using meteorological data from several locations in Japan. It is shown that the convecting solar pond reaches a quasi-steady periodic state after three or four years of operation and that its thermal performance is comparable with that of the salt-gradient solar pond.     

气圈纱线的几个动力学问题

从气圈纱线的非稳定运动出发，研究了气圈纱线的准稳定运动，稳定震动，气圈纱线的固有振动，强迫振动，重点研究了气圈纱线的共振问题。对环锭纺纱中气圈的形态和张力，气圈纱线的固有频率，临界参数与工作参数的计算进行了探讨，并在俄罗斯ＴＩＭ－７６－５Ｍ环锭细纱机上作了实验验证。     

基于准稳态模型的特高压半波长交流输电系统稳态特性与暂态稳定研究

特高压半波长交流输电是一项很有吸引力和前瞻性的远距离大容量输电技术,其稳态特性和暂态稳定研究是其可行性应用研究的基础。首先根据传输线和二端口理论推导出可用于潮流和稳定工程计算的特高压半波长交流线路的准稳态模型;然后在潮流计算的基础上,得出半波长线路的稳态运行特性,并从入、反射波与无功需求2个方面对其电压分布特性进行深入分析。在大量暂态稳定工程计算的基础上,提出特高压半波长交流输电系统的暂态稳定极限和输电能力,并研究最严重故障点和频率变化对系统暂态稳定极限的影响。研究成果对特高压半波长交流输电系统的可行性研究和未来试验工程的实施提供了有力的技术支撑。     

基于准稳态功率转移分布因子的电力系统复杂网络特性分析

基于复杂网络理论及电力系统有功分布的实际特点,并考虑发电节点和负荷节点的有功注入,采用准稳态功率转移分布因子建立改进支路权重模型,该模型可以从支路承担有功传送的功率大小角度反映系统节点之间的连接强度.基于此,建立基于改进支路权重定义下的电力网络测度模型,该模型能够从电网传送有功以及电网拓扑结构角度综合体现系统元件复杂网络特性的多样性和差异性.算例分析结果验证了所提模型的有效性和可行性.     

A SIMPLIFIED THEORY FOR UNSTEADY AERODYNAMIC FORCES ACTING ON AN AIRFOIL FLYING ABOVE SEA-WAVES

A simplified theoretical method based on the quasi-steady wing theory was proposed to study the unsteady aerodynamic forces acting on an airfoil flying in non-uniform flow. Comparison between the theoretical results and the numerical results based on nonlinear theory was made. It shows that the simplified theory is a good approximation for the investigation of the aerodynamic characteristics of an airfoil flying above sea-waves. From on the simplified theory it is also found that an airfoil can get thrust from a wave-disturbed airflow and thus the total drag is reduced. And the relationship among the thrust, the flying altitude, the flying speed and the wave parameters was worked out and discussed.     

A New Model of Fractured Horizontal Well Coupling With the Tight Gas Reservoir at Unsteady State

Abstract

Based on the geologic characteristics of tight gas reservoir, an anisotropic gas reservoir/fractured horizontal wellbore coupling model is derived by the Green functions and Newman product principle at unsteady state. The model considers the gas pseudopressure drop and the simultaneous production of the fractures and horizontal wellbore. It can be used in both unsteady state and quasisteady state. The factors that influence the productivity and the comparison between different producing modes are presented as well.     

液膜法提取废水中柠檬酸动力学传质模型的研究

本研究在探讨液膜法提取废水中柠檬酸机理的基础上,进行合理假设,建立了恒界面状况下的简化非稳态平板动力学传质模型,并利用恒界面条件下的实验数据对拟稳态平板动力学传质模型进行了拟合,取得较为满意的拟合效果。