基于矢量中值滤波的ISS高密度地震数据去噪方法

ISS高密度地震采集是以干扰炮相对有效炮为随机信号的基本理念对地震数据进行采集的方法,其大部分有效信号会淹没于噪声之中。基于此,本文提出-种在十字排列域或检波点域进行矢量中值滤波方法,并针对理论模型简要分析了不同空间滤波参数对保持有效信号和压制干扰信号的影响及处理中应注意的问题;实际单炮地震数据的处理和叠加成像结果表明,该方法在有效压制相干炮噪声的同时,能够较好地保持有效信号,提高资料信噪比,显著优于常规去噪方法的处理效果。     

槽波反射法在工作面小构造探测中的应用

槽波勘探技术具有能量强、信噪比高、探测距离长、勘探精度高等特点,在隐蔽致灾因素探测方面发挥了重要作用。在单一巷道中解决工作面内部的构造问题只能依靠槽波反射法勘探,因为槽波反射勘探可以将激发点和接收点布置在同一条巷道,受空间限制程度较小,在实际应用中有一定的优势和实用价值。结合实例介绍了槽波反射勘探的基本原理,详细说明了此次槽波反射勘探的施工工艺、数据处理流程等。经过验证对比,地质效果良好。只要观测系统合理,槽波反射勘探在解决工作面内部小构造问题方面有一定优势。     

欧洲自动转移飞行器

分析了欧洲自动转移飞行器。首先介绍其研制概况、货运能力,然后分析其总体结构和飞行任务,探讨其发展潜力、总结其设计特色,最后展望其未来应用。     

ISS土壤稳固剂改良菏泽市粘性土路段

文中介绍ISS的发展、理化性质、作用机理，通过试验和工程实践说明了其应用前景。     

An XPS and ISS investigation of passive layers on binary Fe-Al alloys

Passive layers have been formed electrochemically under inert conditions on sputter-cleaned Fe-Al alloys. The aluminum content was 8, 15 and 22 at%, which meets the homogeneity region of α-Fe in the Fe-Al phase diagram. The addition of aluminum reduces the active dissolution current density remarkably compared with that of pure iron. X-ray photoelectron spectroscopy (XPS) studies show an accumulation of aluminum oxide within the center of the passive layer, which is confirmed by elastic-ion scattering spectroscopy (ISS) and XPS depth profiles. Angular-resolved XPS measurements suggest a continuous structural change of the chemical film during its growth. A discussion of the investigations is presented on the basis of a model of oxide growth.     

Input‐to‐state exponents and related ISS for delayed discrete‐time systems with application to impulsive effects

This paper aims to investigate the input‐to‐state exponents (IS‐e) and the related input‐to‐state stability (ISS) for delayed discrete‐time systems (DDSs). By using the method of variation of parameters and introducing notions of uniform and weak uniform M‐matrix, the estimates for 3 kinds of IS‐e are derived for time‐varying DDSs. The exponential ISS conditions with parts suitable for infinite delays are thus established, by which the difference from the time‐invariant case is shown. The exponential stability of a time‐varying DDS with zero external input cannot guarantee its ISS. Moreover, based on the IS‐e estimates for DDSs, the exponential ISS under events criteria for DDSs with impulsive effects are obtained. The results are then applied in 1 example to test synchronization in the sense of ISS for a delayed discrete‐time network, where the impulsive control is designed to stabilize such an asynchronous network to the synchronization.     

Input-to-state stability for networked control systems via an improved impulsive system approach

This paper presents a novel impulsive system approach to input-to-state stability (ISS) analysis of networked control systems (NCSs) with time-varying sampling intervals and delays. This approach is based upon the new idea that an NCS can be viewed as an interconnected hybrid system composed of an impulsive subsystem and an input delay subsystem. A new type of time-varying discontinuous Lyapunov-Krasovskii functional, which makes full use of the information on the piecewise-constant input and the bounds of the network delays, is introduced to analyze the ISS property of NCSs. Linear matrix inequality based sufficient conditions are derived for ISS of NCSs with respect to external disturbances. When applied to the approximate tracking problem for NCSs, the derived ISS result provides bounds on the steady-state tracking error. Numerical examples are provided to show the efficiency of the proposed approach.     

Input-to-state stability of impulsive and switching hybrid systems with time-delay

This paper investigates input-to-state stability (ISS) and integral input-to-state stability (iISS) of impulsive and switching hybrid systems with time-delay, using the method of multiple Lyapunov–Krasovskii functionals. It is shown that, even if all the subsystems governing the continuous dynamics, in the absence of impulses, are not ISS/iISS, impulses can successfully stabilize the system in the ISS/iISS sense, provided that there are no overly long intervals between impulses, i.e., the impulsive and switching signal satisfies a dwell-time upper bound condition. Moreover, these impulsive ISS/iISS stabilization results can be applied to systems with arbitrarily large time-delays. Conversely, in the case when all the subsystems governing the continuous dynamics are ISS/iISS in the absence of impulses, the ISS/iISS properties can be retained if the impulses and switching do not occur too frequently, i.e., the impulsive and switching signal satisfies a dwell-time lower bound condition. Several illustrative examples are presented, with their numerical simulations, to demonstrate the main results.     

Robustness of linear time‐varying systems with relaxed excitation

It is a well‐known fact that linear time‐varying systems with a persistently excited state matrix are exponentially converging and input‐to‐state stable with respect to additive perturbations. Recently, several relaxed conditions of persistent excitation have been presented, which ensure an asymptotic convergence rate in the system. In the present work, it is shown that these conditions are similar and that, under such a relaxed excitation, only nonuniform in time input‐to‐state stability and integral input‐to‐state stability properties can be obtained. The results are illustrated by simulations for a problem of estimation in the linear regression model.     

A converse Lyapunov theorem for, non-uniform in time, global exponential robust stability

Lyapunov-like characterizations are established for the concepts of, non-uniform in time, global exponential robust stability and input-to-state stability for time-varying control systems.