JWP—2全集成电路可调稳频板设计：华北地区遥测地震台网联网…

ＪＷＰ－２稳频电路全部采用集成电路，应用锁相环频率合成技术，频率可调，性能稳定，组装调试方便，可做为原ＷＰ－１稳频电路板的更新换代产品，适当改进功放电路部分，可用在台网的７６８记录器及其它中小型交流同步电机稳频稳速电路中。     

简单、可靠、实用的晶振稳频电路

目前,我国地震台站广泛使用的DD-1、DK-1地震记录仪,均是用同步马达来推动滚筒的。这就需要采用频率稳定性较好的稳频电路。但现用的RC稳频电路在实际工作中一般都不稳定,功耗大、故障较多,因此,有必要对现有的稳频电路进行改进。我国各地台站普遍使用的RC振荡器的振荡频率除受元件参数变化的影响外,还随直流     

DD—1型地震仪稳频电路的改造

晶振稳频电路应用于地震记录仪具有稳定性能好,成本低,功耗小,故障较少,维修方便等优点,因此为愈来愈多的台站所采用。应用石英晶体作振荡源代替原DD-1中RC振荡源的电路,有关杂志曾作介绍,这里向     

基于STM32和LabVIEW的双频激电信号采集系统设计

本文将LabVIEW与基于32位ARM单片机的数据采集电路结合,研究实现了一种高精度、多功能的双频激电信号采集系统.激电信号被采集系统接收后,经信号调理进入模数转换电路转换为数字信号,由USB接口送入基于LabVIEW软件平台的上位机中.上位机对该信号进行滤波选频、幅值测量、频谱分析、幅频率计算等处理,得到目标参数,同时还具有绘图、保存、查看等功能.本文就双频激电信号采集进行了阻容网络模拟实验,先用公式计算出理论视幅频率值,然后搭建电路进行实测.实验结果表明,该采集系统对双频激电信号采集的视幅频率测量误差小、精度高,具有良好的测量效果.     

瞬变电磁低噪声前置放大器研制

为了增大瞬变电磁勘探深度,充分利用晚期道数据,针对瞬变信号频带宽等特点和低噪声运放放大电路的设计原则,通过对放大电路的噪声来源和降低噪声措施的研究,设计了基于超低噪声运算放大芯片LT1028的低噪声差分前置放大电路.建立模型对噪声进行计算和仿真,得出的单运放噪声和总噪声分别为3.2uVrms和4.53uVrms.对实际电路进行噪声测试,得到的噪声频谱图表明在0～100kHz的频率范围内,电路噪声在10～20uVrms之间,设计的差分前置放大电路具有很低的噪声水平,能够满足瞬变信号前置放大的需要.     

多频电磁波传播测井信号测量系统

大量岩石物理实验研究证实地层的复电阻率频谱信息在储层评价方面具有广阔的应用前景,开展多频电阻率测井相关技术研究有利于相应岩石物理研究成果的落地推广.本文基于电磁波传播测井原理对多频电阻率测井的信号测量技术进行了研究.信号测量系统的核心单元为数字信号处理芯片DSP,配合高频VGA(可变增益放大器)芯片和数模转换器实现了高宽频带信号的可编程增益放大.为简化系统结构并降低硬件成本,利用直接频率合成器DDS、乘法器和低通滤波单元对测量信号在不损失信号幅度和相位信息的条件下进行了降频处理,降频后的信号频率固定为50 kHz,与测量信号无关.利用高精度模数转换芯片和FIFO缓存芯片,配合的DFT算法实现了两路高频信号相位和幅度的高速采集计算.由于检波信号频率固定且与测量信号频率无关,DFT算法得以简化以提升幅相分析效率.设计了幅度比和相位差已知的刻度电路对信号测量系统在250 kHz～8 MHz频带内的测量性能进行了测试,在测试频带内的相位差测量绝对误差低于0.3°,幅度比测量绝对误差小于0.6 dB.设计的多频电磁波传播测井信号测量系统具有稳定的测量精度,研究成果对于多频电磁波传播测井的工业化研...     

岩石声频散的实验研究及声波速度的外推

对岩石声频散进行了实验研究，用不同频率的声学探头使用超声波脉冲穿透法对砂岩和泥岩样品进行了测量，并分析了两者的频散现象.结果表明：在51kHz-1MHz频率范围内，在干燥状态下岩芯有频散现象；在饱水状态下，砂岩的频散现象更明显，岩芯中流体的存在是影响纵波频散的一个重要原因.利用频散方程计算不同频率时的速度值，并与实验结果进行了比较，说明频散方程可以较好的描述砂岩与泥岩的频散关系.     

用于电磁法观测系统开机自检的信号发生器实现方法

针对电磁法观测系统在使用过程中的开机自检要求,分析常用测量系统及地球物理仪器的检测信号特征,通过对已有机制进行研究和对比,结合现有信号产生电路的优势,提出一种功耗低、精度高、设计简单的自检信号发生器实现方案.基于该方案设计了一套实现电路,其以CPLD为核心,由精密参考电压源、模拟开关及运算放大器等器件构成,并对该电路进行仿真与测试.通过系统稳定性分析,采用波特图与奈奎斯特图表明信号发生电路的稳定性符合设计要求.经仿真与测试,能够通过换挡开关产生幅值为20μV～2 V、频率范围在1 Hz～100 kHz的自检脉冲信号,频率稳定在1%,重复测试相位稳定度小于1.5%,幅值误差可以优化到1%以内,且能通过其稳定的谐波分量来获取该系统带宽更宽的通道测试响应.测试结果表明,该自检信号发生器电路实际功耗小于0.3 W,20μV～2 V幅值范围和1 Hz～100 kHz频率范围内性能指标的测量结果和仿真结果相符,并成功应用于某监控系统.利用该信号发生器电路实现自检具有操作方便、成本低、易于设计等优点,能够有效的弥补其它自检模式的缺陷.     

MFT-PT型组合多路遥测仪

MFT-PT型遥测仪的研制,是为了在较大范围内（100-200公里）同时传输观测短周期、长周期地震信号和其他地球物理量. 该仪器系统是由脉冲幅度调制和频率调制两种遥测系统复合组成的.其设计特点有如等待式多相多谐振荡器,单管单稳电路等.遥测仪与电子计算机,磁带机配用可以达到快速综合处理地震信号的目的. 该仪器如果采用话音频率,则可以利用电话线路把地震信号送到几千公里之外.遥测仪如果与射频收发讯机配合,则可以构成无线流动台网.     

自相关法单频干扰识别与消除方法

常规单频干扰压制方法需要估算频率、振幅和相位,由于频率和相位与单频干扰呈非线性函数关系,因此任何参数估算方法都会非常费时,且计算效率低下.本文提出的自相关法单频干扰识别与消除方法,利用地震数据自相关函数计算单频干扰自相关函数,采用余弦函数自适应减算法快速估算单频干扰.本方法不需要估算单频干扰的频率、相位和振幅参数,因此...     

Shaking Table Test Study on Dynamic Characteristics of Bridge Foundation Reinforcement on Slopes

With the fast development of bridge construction in mountainous and seismic areas, it is necessary to conduct related research. Based on the design of a shaking table model test, here are the following test results:the filtering effect exists in soil and is affected by the dynamic constraint conditions, the amplitude is strengthened around the natural frequency and weakened in other frequency bands in the Fourier spectrum. Since the acceleration scaling effect occurred on a sloped surface, the acceleration response decreases from the outside to the inside in soil. The dynamic response is relatively strong near the slip surface in bedrock due to the reflection of seismic waves. The failure mode of landslide is decided by the slope angle and slipping mass distribution, and the test shows the front row stabilizing piles should keep a proper distance from bridge foundation so that seismic resistance can be guaranteed for the bridge foundation.     

A regularized magnetotelluric inversion with a minimum support gradient constraint*

Magnetotelluric (MT) inversion is an ill-posed problem and the standard way to address it is through regularization, by adding a stabilizing functional to the data objective functional in order to obtain a stable solution. The traditional stabilizing functionals, in which a low-order differential operator is used, yield a smooth solution that may not be appropriate when anomalies occur in block patterns. In some cases the focused imaging of a sharp electrical boundary is necessary. Even though various experiments have used stabilizing functionals that are suitable to obtain a clear and sharp boundary, such as the minimum support (MS) and the minimum gradient support (MGS) functionals, there are still some limitations in practice. In this paper, the minimum support gradient (MSG) is proposed as the stabilizing functional. Under the uniform regularization framework, a regularized inversion with a variety of stabilizing functionals is performed and the inversion results are compared. This study shows that MSG inversion can not only obtain a clearly focused inversion but also a quite stable and robust one.     

Effects of open trench siding on vibration-screening effectiveness using the two-dimensional boundary element method

The two-dimensional boundary element method in frequency domain is used to investigate the screening effectiveness of the open trench–wall barrier system on reducing vibration generated by a footing. Sheet piles or diaphragm walls are on both sides of the open trench as a vibration barrier in this study. The results showed that screening effectiveness of the open trench without siding is greater than that of the open trench–wall barrier system, which is essential for stabilizing the excavation surface in practice. The trench depth of the barrier system appears to govern the screening efficiency of the barrier, and increase in depth results in better vibration-screening effectiveness. The influence of the open trench width, the embedded length of the trench wall and the distance between the vibration source and the barrier are proven to be insignificant. The screening effectiveness of an open trench barrier with walls increases with the frequency of the vibration.     

On the stability of stratified plane couette flow

Abstract

Unbounded stratified plane Couette flow is shown to be stable against small amplitude disturbances. The Brunt-Väisälä frequency is assumed to be constant. Both viscosity and thermal diffusion are included, and shown to be stabilizing.     

The COMPASS-2 satellite and the ground-based LOIS vector sensing radar facility as novel tools for ionospheric plasma diagnostics

To give a more detailed and complete understanding of physical plasma processes that govern the solar–terrestrial space, and to develop qualitative and quantitative models of the magnetosphere–ionosphere–thermosphere coupling, it is necessary to design and build the next generation of instruments for space diagnostics and monitoring. Novel ground-based wide-area sensor networks, such as the LOFAR Outrigger In Scandinavia (LOIS, LOFAR: Low Frequency Array) radar facility, comprising wide band, and vector-sensing radio receivers with full three-dimensional polarization coverage, and multi-spacecraft plasma diagnostics should help solve outstanding problems of space physics and describe long-term environmental changes. The new digital radio frequency analyzer (RFA) on board the low-orbiting COMPASS-2 satellite was designed to monitor and investigate the ionospheric plasma properties. This two-point ground-based and topside ionosphere-located space plasma diagnostic can be a useful new tool for monitoring and diagnosing turbulent plasma properties. The RFA on board the COMPASS-2 satellite is the first in a series of experiments which is planned to be launched into the near-Earth environment.The main purpose of this presentation is to describe new advanced diagnostic techniques of the near-Earth space plasma and point out the scientific challenges of the COMPASS-2 and LOIS experiments.     

MOSES, a promising concept for marine research

The objective of the EUROMAR project Mobile Station for Environmental Services (MOSES) is the optimization, promotion and harmonization of the design and use of containerized laboratories. The project is designed to study and implement innovative mobile laboratories having the same dimensions as standard shipping containers. They are used in specific environmental activities and designed to be installed on board a ship, an offshore platform or used on land as a multi-activity operative base.     

Handling of waste in ports

A present major problem for ports is arranging adequate reception facilities for ship-generated waste, as the lack of such facilities is a problem to many shipowners. To preserve the environment in and around the ports it is necessary also to deal efficiently with the port-generated waste.

Although international conventions on the retention of waste on board ships for subsequent discharge to shore reception facilities have been ratified by most seafaring nations, a considerable part of the ship-generated waste still goes into the sea. Much of the waste generated in ports will also be dumped in quantities that at least affect the local marine environment. The regulations governing the handling of port-generated waste are often national and/or local legislation, whereas the handling of ship-generated waste is governed by the MARPOL Convention in most parts of the world.

The handling of waste consists of two main phases—collection and treatment. Waste has to be collected in every port and on board every ship, whereas generally only some wastes are treated and to a certain degree in ports and on board ships.

This paper considers the different kinds of waste generated in both ports and on board ships, where and how it is generated, how it could be collected and treated. The two sources are treated together to show how some ship-generated waste may be treated in port installations primarily constructed for the treatment of the port-generated waste, making integrated use of the available treatment facilities.

The different types of wastes can be divided into different categories. A world-wide accepted categorization of ship-generated waste has been established in the MARPOL 73/78 Convention. This will also be used for grouping the port-generated waste.     

从空间飞行器注入电离层的调制电子束产生的电磁波辐射

调制电子束入射进电离层等离子体中会激发电磁波辐射,根据不同试验条件和等离子体状态,激发电磁波的机制也不一样.本文主要讨论半无界稀薄调制电子束沿地球磁场力线从空间飞行器入射到电离层等离子体产生的电磁波辐射,其相应的辐射机理是由于束的纵向约束而产生的电磁波辐射.理论分析和数值计算结果显示,在满足切伦柯夫（Cerenkov）共振条件时,哨声波前向辐射方向图有一个尖锐的峰值,且随着电子束弛豫长度的增加,辐射功率值也相应增大,表明可以通过对电子束的适当调制增强电子束激发的电磁波辐射强度.     

冲击载荷下锚杆-围岩结构冲击失效机制的数值分析

针对冲击地压造成大量锚杆支护结构破坏问题,采用动力数值计算方法,研究冲击载荷作用下锚杆-围岩的动力耦合作用与破坏机制。结果表明:(1)冲击载荷作用下锚杆与围岩振动存在明显的"时差效应",导致锚杆与围岩非同步振动,致使锚固剂承受动态剪切作用。随着锚固长度的增加锚杆与围岩的振动呈同步趋势,削弱了振动"时差效应"引起的锚固剂剪切作用,有效避免锚杆的脱粘滑移失效;(2)随着冲击速度的增大,"时差效应"导致锚杆锚固剂承受动态剪切作用被覆盖,锚杆的破坏失效模式由脱粘或杆体屈服断裂转变为锚杆与围岩统一破坏模式;(3)当冲击载荷频率接近锚固围岩体固有频率时,冲击载荷引起锚杆与围岩共振,锚杆与围岩同步振动速度幅值显著增大,可在相对较低的冲击速度下造成锚杆与围岩整体失效。远离锚固围岩体的固有频率对锚杆-围岩动力相互作用影响较小。     

基于小波变换的结构地震响应与能量计算分析

多分辨分析可将地震信号分解到不同的频段。本文推导了运用多分辨分析计算多自由度体系地震响应的基本公式,讨论了各频段地震信号及结构响应的能量分配。最后,通过多自由度体系的算例验证了弹性体系在原始地震作用下的动力响应可以由该地震作用在时域的各小波分量的动力响应叠加而得,同时将高频抑制后的重构信号应用于近似模型的计算,并利用能量分析明确了地震信号与结构响应在各频段的能量分配。