The measurement of structure-borne sound transmission using impulsive sources

A simple method to measure structure-borne sound transmission is described. Measurement is made of the level difference in the acceleration between two structural elements using a plastic headed hammer as a noise source. The method is at least as accurate as conventional measurements made under steady-state conditions using continuous noise sources and can be carried out with less instrumentation on site and in about a tenth of the time.The portability of the source greatly simplifies the measurements as a hammer can be used to hit structures in a wide variety of positions whereas shakers can only be used in limited situations. In addition, attaching a shaker to a wall can damage the wall surface whereas, with care, a hammer hit will not.     

Existence of integral manifolds for impulsive differential equations in a Banach space

A theorem of existence fort± of integral manifolds of impulsive equations is proved under the assumption that the spectrum of the linear part of these equations may contain points lying in a neighborhood of the imaginary axis.     

Stochastic impulsive control for the stabilization of Lorenz system

This paper derives some sufficient conditions for the stabilization of Lorenz system with stochastic impulsive control.The estimate of the upper bound of impulse interval for asymptotically stable control is obtained.Some differences between the system with stochastic impulsive control and with deterministic impulsive control are presented.Computer simulation is given to show the effectiveness of the proposed method.     

Characteristic exponents of impulsive differential equations in a banach space

The notion of general exponent of impulsive homogeneous differential equations is defined. A formula for the solution of impulsive nonhomogeneous differential equations is obtained and is used to establish a dependence between the existence of bounded solutions of such equations and the general exponent of the respective homogeneous equation.     

脉冲驱动离散混沌系统同步的实验与理论研究

设计了一个具有混沌和超混沌特性的二维离散混沌系统，对其动力学特征进行了分析，从电 路实验上实现了脉冲驱动离散混沌系统的同步, 用数学方法进行分析, 从理论上给出系统实 现脉冲同步的条件, 实验结果与理论分析和数值计算结果一致-另外，还考虑到弱噪声影响 ，实验结果表明：脉冲同步方法仍能保持电路系统的混沌同步，说明系统具有一定的鲁棒性 - 关键词： 脉冲同步 离散系统 电路实验     

A new chaotic system without linear term and its impulsive synchronization

In this paper, a new chaotic system without linear term is presented by ordinary differential equations, and some basic dynamical properties are studied. Moreover, the impulsive synchronization problem of the new chaotic systems is investigated by using uncertain impulsive control matrix. Using the impulsive theory, sufficient conditions are derived for the synchronization of new chaotic systems. Numerical simulation example is provided to verify the effectiveness of the proposed approach.     

基于多项式模型的混沌系统平方和算法脉冲控制

针对一大类混沌系统,提出一种新颖的基于多项式模型的脉冲控制方法.首先,建立系统的多项式模型.其状态方程由系统状态的多项式矩阵与其单项式组成列向量构成.与其他建模方法相比,该方法不必使用任何预制的假设.其次,提出基于平方和优化算法的脉冲控制方法,使得混沌系统的状态能够实现渐近稳定.基于该算法的脉冲控制与基于线性矩阵不等式凸优化算法的结果相比,能得到更大的脉冲间距,从而可以使用较少的控制能量实现同样的控制效果.最后,仿真实验结果验证了本方法的有效性.     

A prototype silicon detector system for space cosmic-ray charge measurement

A readout electronics system used for space cosmic-ray charge measurement for multi-channel silicon detectors is introduced in this paper, including performance measurements. A 64-channel charge sensitive ASIC (VA140) from the IDEAS company is used. With its features of low power consumption, low noise, large dynamic range, and high integration, it can be used in future particle detecting experiments based on silicon detectors.     

A system for industrial surface monitoring utilizing laser-induced fluorescence

A system utilizing laser-induced fluorescence for surface monitoring is described. Results of laboratory and industrial measurements of surface films are reported and further applications of the technique are described.     

A prototype silicon detector system for space cosmic-ray charge measurement

A readout electronics system used for space cosmic-ray charge measurement for multi-channel silicon detectors is introduced in this paper, including performance measurements. A 64-channel charge sensitive ASIC （VA140） from the IDEAS company is used. With its features of low power consumption, low noise, large dynamic range, and high integration, it can be used in future particle detecting experiments based on silicon detectors.     

Exponential dichotomy of linear impulsive differential equations in a Banach space

The dichotomy of linear impulsive equations in a Banach space is investigated.     

Lidar system for visibility monitoring

In the present paper a Lidar (light detection and ranging) system is described. It allows high-speed data acquisition of Lidar signals and meteorological parameters by means of standard instrumentation. The Lidar, controlled by a computer, utilized two laser sources (Nd: Yag and ruby), a modified Ricthey-Chretien telescope and signal detection, storage and real-time monitoring equipment. The whole system was installed in a container for field experiments.     

Quasistationary electric field of atmospheric space charge produced by powerful sound pulse

The electric field created by atmospheric ions in vertical acoustic sounding from the earth's surface is examined. It is shown that ions of different types are completely entrained by an acoustic pulse and create a quasistationary electric field in the surrounding space, particularly on the earth's surface. The shape of the electric-field pulse is calculated is calculated and its amplitude is estimated numerically.Scientific-Research Radio-Physics Institute. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 35, No. 8, pp. 641–651, August, 1992.     

Effect of space charge on subnanosecond current cutoff in powerful semiconductor diodes

High-density current cutoff in an SOS diode is studied with a physicomathematical model including the space-charge effect. If the depth of the p-n junction exceeds 180 µm, the forward pumping time is less than 60 ns, and the backward pumping time is shorter than 20 ns, the subnanosecond cutoff of current with a density of several kiloamperes per square centimeter takes place. The cutoff mechanism is associated with the origination of three high-field zones at the stage of current cutoff: two zones on the p-side, which expand with a velocity close to the saturation value, and one on the n-side, which expands slowly. Taking the space charge into account reduces the role of avalanche multiplication and, as a consequence, improves the switching properties of the diode. It is found that a set of conditions for the electric circuit parameters that specify the pumping current duration and density and for the dopant profile in the semiconductor must be met for subnanosecond current cutoff to occur. The results are compared with experimental data and a model using a quasi-neutral approximation.     

A waveguide high-pass filter system for measuring the spectrum of pulsed terahertz sources

We propose a system for measuring spectra of terahertz (THz) pulses, including single pulses, which is based on high-pass filters (HPFs). The system consists of channels for measuring amplitudes of pulses (initial pulses and those transmitted via HPFs with different cutoff frequencies) and an algorithm for processing of the obtained data. The pulse spectrum is restored by using the iteration method or the amplitude–frequency method. The iteration method of spectrum restoration is applicable in the range of THz pulse durations from 10⁻⁹ s to 10⁻⁷ s. The amplitude–frequency method is applicable to THz pulses with durations exceeding 10⁻⁸ s. The system for measuring of THz pulse spectra was simulated by using the characteristics of specially developed waveguide HPFs. The relative simulation error of determining the central frequency by the amplitude–frequency method is equal to 2 · 10⁻⁶ for THz pulse durations of 10⁻⁵ s and longer.     

激光雷达白天探测大气边界层气溶胶

介绍了自行研制可用于白天探测大气气溶胶的AML-1激光雷达系统,分析了白天工作条件下激光雷达的各种噪声干扰,并给出了抑制噪声干扰的有效措施.其中,天空背景辐射噪声是激光雷达白天工作的主要干扰,通过接收视场角与激光束发散角的严格匹配以及采用高光谱透过率超窄带滤光片可大大抑制天空背景光的干扰.最后,给出了AML-1激光雷达白天测量大气边界层气溶胶的典型结果. 关键词： 大气光学 激光雷达 气溶胶 边界层     

基于X射线的空间语音通信系统

提出了栅控X射线源作为发射器和基于微通道板的X射线单光子探测器作为接收器的X射线通信方案. 搭建了基于X射线的空间语音通信系统, 详细介绍了信号调制发射器、基于微通道板的X射线单光子探测器及信号接收解调器的设计及工作原理. 报道了基于X射线的空间语音通信系统的初步实验结果, 实现了优于20 kbit/s的基于语音信号调制的X射线通信. 实验分析了在不同X射线强度、信号整形时间和阈值设置下通信性能影响, 得出了X射线发射功率限制X射线通信速率的结论, 提出了下一步提高X射线通信性能的改进方案. 关键词： X射线通信 X射线源 探测器