基于VRML的虚拟实验室交互控制方法研究

介绍一种采用VRML开发的实现数字逻辑电路虚拟实验室交互控制的方法。首先从系统的整体体系结构出发，详细地论述了虚拟实验室交互控制的事件驱动原理，然后以芯片插入面包板为例，给出实现这一交互控制过程的具体方法。     

Assessment of Soil Stiffness Properties by Dynamic Tests on Bridges

This paper presents a method to determine soil stiffness properties using measured structural modes of bridges. Normally, the identified mode shapes have to be smoothed. The mode shapes are approximated using functions describing the transverse vibration of distributed–parameter systems. Artificial coefficients are introduced into this solution in order to sum up the error contributions of displacements and its derivatives up to second order. Then, a pier-soil model based on normalized mechanical impedance functions is used. Applying this method along with more than one vertical mode shape leads to acceptable and more accurate results. The amplitudes of pier bottom vibrations are chosen as the suitable weights for the averaging procedure. For the Warth Bridge situated near Vienna, shear wave velocities and shear moduli at the pier foundations have been estimated. The results correspond quite well to the geological investigation.     

Diffusive Behavior of Bedform-Induced Hyporheic Exchange in Rivers

Solute transport in natural streams is a complex phenomenon that involves both in-stream dispersion and mass exchange with the porous zones surrounding the water body. Due to the complex nature of the riverine systems several models may be used to simulate and analyze the transport of solutes with different degrees of complexity. The bedform-induced hyporheic transport is a stream-subsurface exchange mechanism that can be reproduced in controlled systems, such as laboratory flumes. Application of a simple Fickian diffusion model to laboratory data obtained with passive solutes and stationary bedforms proves successful within a range of durations of the contamination process. A dimensionless form of the diffusion coefficient, scaled with dynamic, physical, and geometric properties of the system is derived by comparison with another physically based model. A prediction of the dimensionless diffusion coefficient is obtained as a function of the timescale of the exchange process and is validated with a few sets of results from laboratory tests.     

Interface Characteristics and Laboratory Constructability Tests of Novel Fiber-Reinforced Polymer/Concrete Piles

Conventional pile materials such as steel, concrete, and timber are prone to deterioration for many reasons. Fiber-reinforced polymer (FRP) concrete composites represent an alternative construction material for deep foundations that can eliminate many of the performance disadvantages of traditional piling materials. However, FRP composites present several difficulties related to constructability, and the lack of design tools for their implementation as a foundation element. This paper describes the results of an experimental study on frictional FRP/dense sand interface characteristics and the constructability of FRP–concrete composite piles. An innovative toe driving technique is developed to install the empty FRP shells in the soil and self-consolidating concrete is subsequently cast in them. The experimental program involves interface shear tests on small FRP samples and uplift load tests on large-scale model piles. Two different FRP pile materials with different roughness and a reference steel pile are examined. Static uplift load tests are conducted on different piles installed in soil samples subjected to different confining pressures in the pressure chamber. The results showed that the interface friction for FRP materials compared favorably with conventional steel material. It was shown that toe driving is suitable for installation of FRP piles in dense soils.     

Long‐term Reliability Prediction of 935 nm LEDs Using Failure Laws and Low Acceleration Factor Ageing Tests

Numerous papers have already reported various results on electrical and optical performances of GaAs‐based materials for optoelectronic applications. Other papers have proposed some methodologies for a classical estimation of reliability of GaAs compounds using life testing methods on a few thousand samples over 10 000 hours of testing. In contrast, fewer papers have studied the complete relation between degradation laws in relation to failure mechanisms and the estimation of lifetime distribution using accelerated ageing tests considering a short test duration, low acceleration factor and analytical extrapolation. In this paper, we report the results for commercial InGaAs/GaAs 935 nm packaged light emitting diodes (LEDs) using electrical and optical measurements versus ageing time. Cumulative failure distributions are calculated using degradation laws and process distribution data of optical power. A complete methodology is described proposing an accurate reliability model from experimental determination of the failure mechanisms (defect diffusion) for this technology. Electrical and optical characterizations are used with temperature dependence, short‐duration accelerated tests (less than 1500 h) with an increase in bias current (up to 50%), a small number of samples (less than 20) and weak acceleration factors (up to 240). Copyright © 2005 John Wiley & Sons, Ltd.     

卫生检验实验室信息管理系统(H-LIMS)的开发设计

卫生检验实验室信息管理系统(H-LIMS)是一个用于卫生检验业务管理的软件系统,是针对产品检验和防病检验业务从样品受理、检验到报告编制、签发、发出的金过程进行计算机管理,对人员、设备、物料、环境、质量文件等影响检验质量的各个要素进行规范化管理.     

LabVIEW在实验室远程控制中的应用

该文介绍了LabVIEW的功能特点、程序设计结构、运算形式和实用工具软件包,并以远程电子线路实验室系统为例介绍了LabVIEW在实验室远程控制中的应用。     

On the use of laboratory ocean circulation models to simulate mesoscale (10–100 km) spreading

The development of hydrodynamic numerical models for environmental studies depends on good benchmarks to calibrate and validate the physics and numerical codes. Laboratory models of non-linear and coupled physics in topography for which no analytical solutions are available can provide such valuable benchmarks. Although field data are necessary for a final validation, they are often of less value for developing numerical models, since a truly synoptic coverage of a scenario is seldom found, knowledge of the forcing conditions is imperfect and average conditions of a non-linear system are seldom obtained by applying average boundary conditions.The role of laboratory models and experiments for providing information on turbulence in complicated topography is indisputable. The high topographical resolution of these models reveals how narrow and filamentous many of the flow features can be, as often seen in satellite images. Such filaments enhance diffusion through a process known as shear dispersion. The filaments are also of concern for the interpretation of sparse field measurements and for computing the mesoscale (10–100 km) spreading characteristics. Time histories of dye clouds and clusters of particles in laboratory simulations of ocean currents, without wind, show much larger spreading than particle spreading due to strong winds. The results demonstrate that numerical models need high resolution and/or good parametrization of the spreading characteristics, which vary both in space and time, to achieve their goals. It is proposed that the differences between numerical and laboratory simulations of dispersion, with identical forcing, be parametrized as a size-dependent, or time-dependent random walk diffusion in the numerical code.The laboratory results amply show that spreading is greatly enhanced by shear dispersion, and that assessments of the consequences of accidental oil spills or releases of radionuclides, for example, must take this into account. Island communities in tidally active regions are particularly prone to the consequences of a rapid dispersion of contaminants.     

Comparison between cellular automata and linear feedback shift registers based pseudo-random number generators

A detailed comparison between pseudo-random number generators (PRNGs) based on cellular automata (CA) and linear feedback shift registers (LFSRs) is presented in this paper. Various statistical tests have been applied in order to reveal the advantages and disadvantages of both approaches. Both LFSRs and hybrid additive cellular automata (HACA) produce satisfactory PRNGs. HACA operate at higher speeds than LFSRs with the same characteristic polynomials. Regarding the silicon area, direct comparisons between the two approaches cannot be made since it depends on the PRNG length. However, the inherent modularity of HACA reduces the silicon area occupied by them and, when long feedback paths are used, the silicon area occupied by LFSRs increases.     

热风式大气湍流模拟装置的哈特曼测量

大气湍流是由于大气温度、压强的随机变化引起大气折射率随机改变而产生的。遵循这一原理,热风式湍流模拟装置对传输光束周围的空气加热,用风扇抽吸热空气产生湍流,通过改变加热温度和风扇的转速,模拟不同强弱的湍流。用哈特曼传感器对该装置进行测量并采集数据,通过波前斜率处理复原波前,在此基础上从时间域和空间域等方面分析所产生湍流的特点,并与理论进行比较。结果表明,该装置能产生基本符合大气湍流统计理论的湍流。