A real time processing system of seismic waves using personal computers — Function and characteristics

Conclusions The real-time processing system of CTSN performs following: A/D conversion; automatic event detection; event data saving; automatic measure of P and S arrivals; event location and print out the calculated results. It is corrected at ny moment by using the off-line system. Since December 1993, this system has been operating normally in the CTSN. More than 4 000 earthquakes have been recorded in the system. It has high accuracy in automatic picking P and S arrivals. The location of the earthquakes determined by on-line system are close to those given in published catalogues which are determined by manual procedure. This system can finish locate event in three minutes. It also gives satisfactory epicenter locations for distant events by inputting manually S arrivals in the off-line system. The operation of this system had brought the technical superiority of the CTSN. It not only reduces the labor intensity and simplifies the working procedure, but also makes our research facility into the superior ranks in this field of our country. In conclusion, the real-time processing system of seismic wave provides technical support for the daily requirements of monitoring seismic activity as well as a lot of digital waveform data used seismic research in Sichuan area. This subject is sponsored by the Scientific and Technical Committee of Sichuan Province.     

Seismotectonic and liquefaction studies of an industrial site in Northern India

Foundation soil of the proposed fertiliser complex in Northern India is examined for its susceptibility to liquefaction during an earthquake. Information on geotectonic set up and earthquake occurrences in the region around the site is used for defining the earthquake parameters of the ground motion. The effective peak ground acceleration for the site is estimated to be of the order of 0.15 g. Laboratory tests were carried out on soil samples obtained from the site on a horizontal vibration table. The test results were used in determining the possibility of liquefaction employing the methodology developed at the Department of Earthquake Engineering, University of Roorkee. About 10 m of a thick soil layer below the top 1.5 m stiff clay is likely to liquefy. Remedial measures used at the site to counter the possibility of liquefaction are mentioned.     

Fractional flow dimensions and hydraulic properties of a fracture-zone aquifer, Leppävirta, Finland

 In order to characterize the hydraulic properties of an aquifer in Finland comprising two subvertical fracture zones, observation-well responses were matched with generalized radial flow (GRF) type curves. The responses in six wells out of seven are consistent with the GRF model. The fractional flow dimensions (1–1.2 and 1.5) were determined by regression analysis of straight-line slopes and type-curve matching. In each test, the flow dimensions in the neighboring fracture zone range from 2–2.25. Comparisons of the late-time responses with the asymptotic GRF solution and the flow dimensions obtained by reversing the pumping and observation points suggest homogeneous hydraulic properties. Deviations in responses can be explained by flow-path tortuosity. After assessments of the extent of the flow and radial distances along the fracture system, hydraulic conductivities and storativities were determined from the results of the type-curve matching procedure. The obtained hydraulic conductivities are 1.3×10^–5 to 7.9×10^–5 m/s and 5.0×10^–6 to 2.5×10^–5 m/s for the western and the eastern fracture zones, respectively. The results were verified by applying them to analytical solutions for pumping wells. The calculated pumping-well responses are consistent with the observations. The analysis of flow dimension also enhances qualitative interpretations on the hydrogeology of fracture zones. Received, April 1997 · Revised, September 1997 · Accepted, May 1998     

Multi-scale analysis of disturbance regimes in the northern Chihuahuan Desert

Remote sensing facilitates cross-scale validation, enables analysis of processes and patterns in time and space, and is thus viable for the conduct of earth system science. Multi-scale analyses of natural vegetation patterns and processes in the northern Chihuahuan Desert show that natural vegetation is capable of recovering from short-term, high intensity disturbances such as an atomic bomb blast. In contrast, mesquite dunelands persist on other sites grazed before the blast, showing the Chihuahuan is less resilient to long-term low intensity disturbances. A geographic information system (GIS) was used to register historical Landsat Multi-Spectral Scanner (MSS) data acquired over Trinity National Historic Site (TNHS), New Mexico, and the vicinity. Aerial and ground photography provide supporting detail, at finer scales, regarding the distribution and pattern of natural vegetation at TNHS Ground Zero and adjacent weapons impact targets. Aside from initial mechanical or thermal damage to vegetation from the first atomic test over a half century ago, analyses of vegetation at satellite and airphoto scales show no apparent persistent blast effects around TNHS.     

桩材料阻尼对动测曲线的影响研究

基于严格的数学模型,从桩材料的阻尼对法桩动测曲线的影响进行研究发现,桩材料阻尼对测试曲线有着不同于拉侧土阻尼的影响,尤其是对瞬态反射波法测试曲线的桩尖反射形状及到达时间影响比较明显。     

线性-动态规划改进模型及其应用

Becker和Yeh于1974年提出的线性(LP-DP)模型是一种功能很强的优化模型。然而该模型是针对梯级发电库群实时调度提出的,对并联系统并不适用。且该模型在理论上还不够严密,需进一步完善。本文所提出的LP-DP改进模型不但在理论上比较完整,而且扩展了应用范围,提高了优化效益。该模型现已成功地应用于江西省水火电力系统实时优化调度之中。     

Real-Time Tsunami Forecasting: Challenges and Solutions

A new method for real-time tsunami forecasting will provide NOAAs Tsunami Warning Centers with forecast guidance tools during an actual tsunami event. PMEL has developed the methodology of combining real-time data from tsunameters with numerical model estimates to provide site- and event-specific forecasts for tsunamis in real time. An overview of the technique and testing of this methodology is presented.     

Test and numerical simulation of a new type of hybrid control technique

In this paper, a new hybrid control technique, based on a combination of base-isolation and semi-active variable stiffness/damping in a superstructure, is presented. To illustrate the efficiency of the proposed control system, model tests on a mini-electromagnetic shaking table and a numerical simulation were performed. The test and numerical calculation results indicate that this new hybrid control mode with additional damping and smaller additional stiffness can achieve a better control efficiency.     

Effect of a Mobile Fine Fraction on Slug Test Results

In recent slug testing at our field site there seemed to be a dependence on flow direction and initial slug height in some of the results for hydraulic conductivity that could not be explained by any known models. At first, we thought the dependence on flow direction and initial height was the result of slug length and friction in the annular space between the slug and casing. Later slug testing with a packer eliminated the effect of the slug in the wellbore, but the initial head and directional dependence observed earlier remained for the packer data. This indicated possible well development problems, so a program of well development was instituted and slug tests were performed at various points in this program. We were not able to eliminate the head and directional dependence of the results for the hydraulic conductivity by well development. However, we have arrived at some conclusions that may be helpful to others interpreting slug test data in aquifers with a mobile fine fraction. It seems that well development and slug testing can cause fine material to be redistributed in an aquifer. Apparently in our slug testing and development program, we have created an artificial distribution of fine material that differs with radius, causing the apparent hydraulic conductivity to differ with volume injected or withdrawn. Directional dependence may be caused by the water moving away from the well carrying fines, resulting in a build up of fine material at some radius and a lower apparent hydraulic conductivity.     

DECLINING STUDENT PERFORMANCE IN COLLEGE GEOGRAPHY AND THE DOWN-WRITING OF TEXTS

Student preparation for college showed significant declines through the 1970s, according to Scholastic Aptitude Tests and other indices. During the same period, scores declined on my standardized, mid-term exam used for introductory physical geography at UCLA. I suggest that the latter is primarily caused by the former. As a result of declining preparation and abilities, many physical geography texts have been down-written to a high-school level. These texts have grave implications for the quality of learning, recruiting of quality students, and academic respect for geography as a discipline.