上游参数空间的激波分布

本文从Rankine-Hugoniot关系出发,采用阿尔文数A₁、激波角θ₁和气压-磁压比β₁作为上游参数,导出了参数空间中激波区边界的解析表达式;讨论了各类激波在参数空间的分布范围和相互关系;指出只有当上游背景阿尔文波速超过声速时,才有可能通过中间激波实现快、慢激波之间的空间连接和时间演化.     

天津地区小震应力状况

本文测定了天津地区1985—1990.9年间M_L=3.0以下小震的震源参数,共125次。结果表明:地震应力降△σ一般都不高,多数低于1.3Mpa;区域剪切应力和地震应力降均有明显的增高趋势。1989年末开始下降。由P波测定的介质Q值蓟县平均为350,宝坻、宁河、静海为250,天津西稍高。小震平均震源机制主压应力轴由北西9°,向西偏转26°。这些变化,不仅反应本地区应力调整过程,而且是华北区域应力变化过程的局部显示。     

广西中强地震迁移的探讨

据广西有史记载的地震资料表明:广西的中强地震存在明显的迁移规律。即逐步地由桂东北向桂西南迁移的规律。     

Geotechnical properties of a chemically stabilized soil from Malaysia with rice husk ash as an additive

Summary The stabilization of Malaysian soil by mixing with rice husk ash, a locally available waste material, to improve its engineering properties is described. Stabilizing agents, i.e. cement and lime, were added to produce the reaction products which are responsible for the enhancement of the engineering properties. Based on the strength development, it seems that lime is the more effective stabilizing agent. However, the cheap waste material can be used as partial replacement for the more expensive cement in the cement-treatment of the soil. A durability study was carried out to evaluate the effectiveness of this stabilization method.     

Observations of high co rotational lines in post-AGBs and PN

We present a preliminary interpretation of high CO rotational line data obtained from KAO. The possibility of either a PDR or a shock model is considered in order to explain the observations.     

强地震动数据采集实时系统研究

本文介绍了GDQJ-2型强地震动数据采集实时系统的结构原理和技术性能,着重介绍了一个台网形式的数据采集实时系统数据的处理流程、系统软件的多线程处理、对串口和Modem的操纵方式、数据帧的构成和压缩方式等。该系统可用于强地震观测和工程振动测量。     

A possible shock wave in the intergalactic medium of the cluster of galaxies A754

The cluster of galaxies A754 is undergoing a merger of several large structural units. X-ray observations show the nonequilibrium state of the central part of the cluster, in which a cloud of cold plasma ～500 kpc in size was identified amid the hotter cluster gas. The X-ray image of A754 exhibits a brightness discontinuity, which can be interpreted as a shock wave in front of a moving cloud of dense gas. The shock parameters are determined from the jump in intergalactic gas density using the ROSAT image. The estimated Mach number is M₁ = 1.71 _?0.24 ^+0.45 at a 68% confidence level.     

Efficient seismic response data storage and transmission using ARX model‐based sensor data compression algorithm

This paper presents a linear predictor (LP)‐based lossless sensor data compression algorithm for efficient transmission, storage and retrieval of seismic data. Auto‐Regressive with eXogenous input (ARX) model is selected as the model structure of LP. Since earthquake ground motion is typically measured at the base of monitored structures, the ARX model parameters are calculated in a system identification framework using sensor network data and measured input signals. In this way, sensor data compression takes advantage of structural system information to maximize the sensor data compression performance. Numerical simulation results show that several factors including LP order, measurement noise, input and limited sensor number affect the performance of the proposed lossless sensor data compression algorithm concerned. Generally, the lossless data compression algorithm is capable of reducing the size of raw sensor data while causing no information loss in the sensor data. Copyright © 2005 John Wiley & Sons, Ltd.