螺线空间阵性能研究

为使水下测试声阵拥有较强的抗干扰能力,常要求阵列具有较低的旁瓣。该文提出了一种螺线空间阵设计方法,可利用螺线结构的空间稀疏分布特性,大幅降低体积阵的旁瓣高度,提高对水下目标的方位估计能力。文中给出了螺线空间阵的构造方法和阵元坐标参数,并与圆柱阵、双锥阵等常规体积阵进行了指向性、方位估计能力、阵增益的对比,仿真结果表明螺线空间阵在水平方向上的指向性旁瓣最低、最平坦,对目标进行方位估计时的伪峰高度最低,目标的方位估计能力相比双锥阵、圆柱阵提升显著。

水下三弹性柱壳耦合声散射特性研究

为研究3个并排无限长弹性圆柱壳受垂直于柱轴方向的平面声波作用的声散射特性,采用Fourier级数展开法建立了圆柱壳声散射数学物理模型,考虑了三圆柱壳弹性振动声辐射和刚性声散射,建立了3个壳体辐射声场和刚性散射声场的耦合作用关系,比对了等效散射强度的刚性散射分量与弹性散射分量,并分析了三壳体等效散射强度特性。计算结果表明:当ka2>40,在频率f=3000 Hz以上频段,弹性分量对等效散射强度变化趋势的贡献可以忽略。当ka2>30,在频率f=2400 Hz以上频段,弹性散射分量对等效散射强度影响不超过3 dB;三壳与单壳的等效散射强度在0°入射角方位相当,其它方位三壳体等效散射强度明显大于单壳体。本文的理论公式可推广到任意数量阻抗柱的声透射和声反射问题。

翟双庆从气郁痰扰论治强迫症经验

总结翟双庆教授从气郁痰扰论治强迫症的临床经验。认为气郁痰扰是强迫症的核心病机,气郁、痰浊相互影响,共同致病。气郁痰扰的形成与心、脾、肝、胆等脏腑功能失调密切相关。临证治疗应以理气祛痰、重镇安神为核心治法,以自拟解郁化痰汤为基础方,并根据患者病情进行分期治疗,用药注重配伍健脾益胃、养心安神、疏肝利胆、滋阴温阳之品;同时强调临证灵活选用龙骨、龙齿、牡蛎、珍珠母等重镇药以重镇安神。

水下壳体结构低频辐射声功率预报方法研究

针对水下壳体结构低频辐射声功率预报问题,提出了在水下柱形结构中采用波数域单柱面声场分离技术与超声声强法相结合的方法。首先在非消声水池中获得柱形结构近场单全息面上的复声压和径向振速,通过单柱面声场分离技术获得向外传播的声波;然后采用超声声强法对向外传播声波中的倏逝波进行过滤,获得能够被传递到远场的传播波成分,进而对壳体远场辐射声功率进行预报,并与自由场辐射声功率进行对比,验证该方法对水下柱形结构辐射声功率预报的有效性;最后,分析影响预报结果精确度的因素,探究该预报方法的适用条件。结果表明,该方法对于声学水池中柱形结构低频声辐射预报有一定的工程应用价值,对减振降噪具有指导作用。

Underwater sound scattering characteristics of three paralleling flexible cylindrical shells

To investigate the sound scattering characteristics of three paralleling flexible cylindrical shells with the plane incident wave,a mathematical model is established with Fourier series expansion method which involves the flexible vibration,the sound radiation and the rigid scattering of each shell and their coupling through the sound field.With the model,the difference between the flexible radiation term and the rigid scattering term of the sound field of three combined cylindrical shells is calculated and analyzed,as well as the scattering strength of the shells.The results demonstrate that the flexible radiation term can be ignored for ka2>40(f>3000 Hz),and for the instance of ka2>30(f>2400 Hz),the scattering strength error without the flexible radiation term is less than 3 dB.The scattering strength of three shells is approximately equal to the scattering strength of single shell while the incident angle is 0°or vicinity angle,whereas the scattering strength of multi-shells is higher than that of single shell for the distinct incident angle.The mathematical model in this paper could be easily extended to solve the problems of transmission and reflection of random number of resistant cylindrical shells.