飞机壁板结构的高温声疲劳试验方法

本文对飞机发动机部位常用典型壁板结构的高温声疲劳试验进行了论述．其内容涉及环境模拟、声场测量、声疲劳载荷谱的确定、高温环境下裂纹监测、高温下一阶频率确定等问题．并给出了ＧＨ１４０材料典型壁板结构件的试验结果     

高温热管声速极限的实验研究与理论分析

高温热管是公认的被动式高温传热器件,以及明显高于相同几何尺寸金属材料的当量导热率,使其成为研究热点,并具有广泛的应用前景。在高温热管的蒸汽流动中,当喉部流速达到声速后,会出现声速传热极限,主要表现为冷凝段温度持续降低,传热量停滞不增,以及蒸汽的阻塞状态。本文设计、制备了高温热管传热器件,以高频感应方式为热源,盘管式水冷套为冷源,搭建了可以定量测试高温热管声速极限的实验台,并应用理论模型进行了验证。实验测试了高温热管在高热流加热条件下的冷态启动过程,以及稳态传热状态下的温度、热流等基本物理量,并对此进行了理论分析。实验结果表明:长径比、加热热流、工作温度是影响高温热管声速极限的主要因素。     

Controlling the level of the sonic boom generated by a flying vehicle by means of cryogenic forcing. 1. Cooling of the vehicle surface

The possibility of controlling the sonic boom level by means of cooling the surface of a flying vehicle is discussed. The effect of surface cooling on the formation of the perturbed flow structure at large distances from the vehicle is demonstrated by an example of a modified power-law body of revolution. The intensity of the intermediate shock wave and the perturbed pressure pulse near the body are seen to decrease, which expands the altitude range of the region where the sonic boom is reduced (down to 50%). At larger distances from the body, cryogenic forcing ensures a 12% decrease in the bow shock wave intensity. The possibility of controlling the process of formation of wave structures near the surface, such as barrel shock waves, is demonstrated. An explanation of the cryogenic forcing mechanism is offered. __________ Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 49, No. 6, pp. 88–98, November–December, 2008.     

声子晶体中第二能带的回波负折射

文章从理论和实验上研究了二维三角晶格声子晶体第二能带具有回波（backward-wave）效应的负折射现象。Bragg散射将第二能带等频线（equifrequency surface）分成两类，它们分别凹向简约布里渊区（BZ）的K点和Г点，并由此导致了两种不同的回波负折射现象。理论和实验证明，这两类负折射的角度与声波的频率以及入射角的变化关系截然不同，同时在第二能带中，不仅存在回波负折射，还存在回波正折射，这两种折射所具有的回波效应都可以用于通过位相补偿效应来突破衍射极限。上述现象和左手材料中以及声子晶体第一能带中的折射现象是不相同的，揭示了声子晶体，第二能带具有更丰富的物理现象．     

物理实验中的不确定度及其在声速测量过程的应用

本文对物理实验中的不确定度进行了比较系统的介绍,并将其应用到声速测量这个典型的物理实验当中,显示出不确定度在物理实验的数据处理中的重要性。     

高对称型声子晶体自准直弯曲及分束

基于二维六方晶格声子晶体的高对称性, 通过裁剪声子晶体模型, 实现声波自准直束60°和120°全反射弯曲, 证实点源声波的准直弯曲和亚波长成像. 在六方晶格声子晶体中引入线缺陷, 实现自准直束的60°和120°弯曲及分裂, 详细分析了缺陷尺寸对入射准直束的60°(或120°)弯曲声束与透射声束能量分配的影响. 本文的工作可以使基于自准直效应的应用更加灵活.     

基于军事价值的武器装备体系结构优化模型

首先研究了武器装备评价指标体系的层次结构,在每个评价指标下,给出了标准指标值的计算模型和指标效用值的计算模型,在此基础上构建了武器装备体系的结构价值模型,利用该模型计算武器装备体系的结构价值,依据此价值对武器装备体系结构方案进行排序.     

基于云推理模型的武器装备研制风险评估研究

武器装备研制过程充满了不确定性和风险,因此对武器装备研制风险进行研究对于实现武器装备研制目标具有重要的意义.界定了武器装备研制风险相关概念,介绍了云推理理论,构建了武器装备研制风险的云推理评估模型,实现了定性变量与定量变量相互映射,最后,通过实例对模型进行了验证.     

Steady/unsteady aerodynamic analysis of wings at subsonic,sonic and supersonic Mach numbers using a 3D panel method

This paper treats the kernel function of an integral equation that relates a known or prescribed upwash distribution to an unknown lift distribution for a finite wing. The pressure kernel functions of the singular integral equation are summarized for all speed range in the Laplace transform domain. The sonic kernel function has been reduced to a form, which can be conveniently evaluated as a finite limit from both the subsonic and supersonic sides when the Mach number tends to one. Several examples are solved including rectangular wings, swept wings, a supersonic transport wing and a harmonically oscillating wing. Present results are given with other numerical data, showing continuous results through the unit Mach number. Computed results are in good agreement with other numerical results. Copyright © 2003 John Wiley & Sons, Ltd.     

American Physicists, Nuclear Weapons in World War II, and Social Responsibility

Social responsibility in science has a centuries-long history, but it was such a minor thread that most scientists were unaware of the concept. Even toward the conclusion of the Manhattan Project, which produced the first nuclear weapons, only a handful of its participants had some reservations about use of a weapon of mass destruction. But the explosions over Hiroshima and Nagasaki not only made society more aware of the importance of science, they made scientists more aware of their responsibility to society. I describe the development of the concept of social responsibility and its appearance among American scientists both before and after the end of World War II.Expanded version of a talk in Hiroshima, Japan,August 10, 2003.Lawrence Badash is Professor Emeritus of History of Science at the University of California, Santa Barbara.