位相连续变化型毫米波衍射天线的性能分析

报道了一种新型毫米波天线—衍射天线的测量结果．经分析讨论说明，这种天线具有良好的电性能．     

正则化长波方程的三次样条差分模拟

本文对正则化长波方程(RLW方程)的时间、空间项分别采用三次样条公式进行离散,所得到的差分方程为三点、三层隐格式,对时间的精度为四阶,对空间的精度为二阶,每个时间步只需求解一个三对角方程组,而三次样条配置法在每个时间步中需要求解三个三对角方程组。本文对单个孤立波的演化进行了计算,参数与文[8]相同,其结果与解析解的最大绝对误差均保持在10~(-3)的量级以内,与文[8]给出的数值方法精度相当。对两、三个孤立波的相互碰撞,本文结果显示出在忽略10~(-3)量级的误差后,碰撞前后的孤立波形状保持不变,无论是一个孤立波的演化,还是两、三个孤立波相互碰撞,当将波形放大100倍后均可以发现有振荡的尾波,这说明这类振荡尾波的产生并非真实的物理现象,而是由数值误差产生的。本文认为仅从工程应用的意义上说,RLW方程具有孤立子性质的结论是可以接受的。     

HYDRODYNAMIC FORCE ON SMOOTH HORIZONTAL CYLINDER IN UNIFORM OSCILLATORY FLOW

ＨＹＤＲＯＤＹＮＡＭＩＣ　ＦＯＲＣＥ　ＯＮ　ＳＭＯＯＴＨ　ＨＯＲＩＺＯＮＴＡＬ　ＣＹＬＩＮＤＥＲ　ＩＮ　ＵＮＩＦＯＲＭ　ＯＳＣＩＬＬＡＴＯＲＹ　ＦＬＯＷＨＹＤＲＯＤＹＮＡＭＩＣＦＯＲＣＥＯＮＳＭＯＯＴＨＨＯＲＩＺＯＮＴＡＬＣＹＬＩＮＤＥＲＩＮＵＮＩＦ...     

地震数据采集系统中频谱均衡滤波器的理论设计

地层的高频吸收衰减效应是导致地震勘探分辨率不高的主要原因，在高分辨率野外地震数据系统中，频谱均衡滤波器所设置的重要部件。文章以频谱均衡滤波器的原理和地层吸收衰减特性为基础，用计算机模拟的方法研究地层吸收衰减使分辨率降低的程度和频谱均衡滤波器对分辨率的补偿效果，给出了较好的频谱均衡滤波器的设计方案。     

A damage identification technique for CF/EP composite laminates using distributed piezoelectric transducers

In this study, a damage identification approach was developed for carbon fibre/epoxy composite laminates with localized internal delamination. Propagation of the Lamb wave in laminates and its interaction with the delamination were examined. The fundamental symmetric Lamb wave mode, S₀, and the lowest order shear wave mode, S₀^′, were chosen to predict damage location. A real-time active diagnosis system was therefore established. This technique uses distributed piezoelectric transducers to generate and monitor the ultrasonic Lamb wave with narrowband frequency. The two-way switches were employed to minimize the number of transducers. A signal-processing scheme based on the time–frequency spectrographic analysis was utilised to extract useful diagnostic information. Also, an optimal identification method was applied on damage searching procedure to reduce errors and obtain the diagnostic results promptly. Experiments were conducted on [0/−45/45/90]_s CF/EP laminates to verify this diagnosis system. The results obtained show that satisfactory detection accuracy could be achieved.     

The Effect of the Charge Fluctuation of Dust Parti-cles on Ion-acoustic Wave Excited Through Ionization Instability

The effect of the charge fluctuation of dust particles on ion acoustic wave (IAW) excited through ionization instability was investigated. The hydrodynamic equations and linear time-dependent perturbation theory served as the starting point of theory, by which the dispersion relation and growth rate of the IAW were given. By comparing the results with the case of constant dust charges, it was found that the charge fluctuation of dust particles reduces the instability of the wave mode.     

厚断面球铁的声速

论述了影响厚断面球铁声速和声波衰减的各种因素。指出，必须在应力状态下同时考核声速和声波衰减，以作为判别厚断面球铁材质的一种手段。     

A Low-Power Wide-Dynamic-Range Analog VLSI Cochlea

Low-power wide-dynamic-range systems are extremely hard to build. The biological cochlea is one of the most awesome examples of such a system: It can sense sounds over 12 orders of magnitude in intensity, with an estimated power dissipation of only a few tens of microwatts. In this paper, we describe an analog electronic cochlea that processes sounds over 6 orders of magnitude in intensity, and that dissipates 0.5 mW. This 117-stage, 100 Hz to 10 KHz cochlea has the widest dynamic range of any artificial cochlea built to date. The wide dynamic range is attained through the use of a wide-linear-range transconductance amplifier, of a low-noise filter topology, of dynamic gain control (AGC) at each cochlear stage, and of an architecture that we refer to as overlapping cochlear cascades. The operation of the cochlea is made robust through the use of automatic offset-compensation circuitry. A BiCMOS circuit approach helps us to attain nearly scale-invariant behavior and good matching at all frequencies. The synthesis and analysis of our artificial cochlea yields insight into why the human cochlea uses an active traveling-wave mechanism to sense sounds, instead of using bandpass filters. The low power, wide dynamic range, and biological realism make our cochlea well suited as a front end for cochlear implants.     

声波时差测井在鄂尔多斯天然气勘探中的地质应用

本文应用声波时差测井资料判别划分地层压实异常段,并结合其它测井资料对盖层进行质量评估,寻找油气有利聚集带(段),为勘探提供有利区域和评价依据。     

光泵腔式NH3分子亚毫米波激光的调谐特性研究

通过求解量子系统的密度矩阵方程，计算了不同管长和不同输入输出功率反射系数的光泵腔式激光器对281um和90.4um的亚毫米波信号的调谐特性，给出了其调谐特性随信号波长λ，激光管长l和功率反射系数R的变化关系。