高速列车模型实验系统及其测试结果分析

高速列车在进出隧道时 ,会产生一系列气动效应。模型实验是研究这一问题的有效方法。西南交通大学土木学院借鉴国内外的经验 ,研制建立了高速列车模型实验系统。本文对该实验系统进行了介绍 ,并对测试结果进行了分析 ,得出了高速列车在进入隧道过程中 ,压缩波产生、变化的一些规律。

“光谱”模型实验系统结构研究

由计算机科学和决策科学相结合而形成的计算机决策支持系统,把计算机在数据处理中的应用推向一个支持决策的新阶段。为研究、学习国外决策系统,运用探析方法分析了《光谱》中等模型实验系统(MMK《СПЕКТР》)的特点和功能,得出了系统总体、数据管理部分和模型管理部分的设计方法。为进一步研究该系统打下了基础。

基于UML的实验教学系统建模技术应用研究

随着现代化网络教育技术的发展,在网络环境下对于全面有效的专业实验教学管理系统的研究和建立已经成为近几年的热点问题之一。文章基于UML建立了一种实验教学系统模型,有效解决了预约和排课中经常出现的冲突问题,为高校提供了一种通用性能良好的实验教学原型系统。

景观生态学的实验研究方法综述

实验是生态学研究的基本途径之一 ,对其理论的检验和发展至关重要。 2 0世纪 80年代后期 ,实验研究途径开始应用于景观生态学 ,至今方兴未艾。近年来 ,“景观”的生态学内涵更加强调“不同尺度上的空间异质性”。而研究对象的尺度和空间异质性往往正是景观生态学实验设计和操作所面临的困难。自然界景观格局与过程中客观存在的自相似结构为景观生态实验设计提供了可行性。现有的景观生态学实验方法可分为 3类 :野外比较观测性实验仍是目前应用较多的方法 ;操作性实验设计更严密 ,结果更可靠 ,但受现实条件的限制更大 ;计算机模拟实验是克服实验条件的困难的一个替代途径 ,并对理论的检验与发展特别有用。这 3类实验方法各自存在不同的优势和局限 ,彼此难以替代。景观生态实验方法主要从种群、群落和生态系统实验中借鉴并发展而来 ,但其实验设计在科学问题和操作尺度上具有显著的特点。从空间范畴来讲 ,景观生态实验包含斑块、边界、景观、斑块景观 4种 ,其所对应的生物群体组织水平、实验设计所涉及的问题和解决的方法都有所不同。多尺度的对比实验有助于了解生态现象与机制的尺度推移规律 ,是目前实验研究的难点和焦点之一。实验模型系统 (EMS)途径来源于生态系统实验。

工程制图中教学难点的“体验教学”设计

"体验教学"是一种适应新经济时代人才培养模式需要的新的教学理念。在此理念指导下,作者以营造"体验"环境,建构由低级向高级过渡渐次递进的"体验"历程为手段,应用最新的JAVA 3D技术设计了工程制图模型的参数化虚拟实验系统,并针对工程制图中的教学难点,即截交线和相贯线进行了相关的"体验教学"设计。

Hepatitis C Virus Experimental Model Systems and Antiviral drug Research

An estimated 130 million people worldwide are chronically infected with hepatitis C virus (HCV) making it a leading cause of liver disease worldwide. Because the currently available therapy of pegylated interferon-alpha and ribavirin is only effective in a subset of patients, the development of new HCV antivirals is a healthcare imperative. This review discusses the experimental models available for HCV antiviral drug research, recent advances in HCV antiviral drug development, as well as active research being pursued to facilitate development of new HCV-specific therapeutics.

A Modified Peng-Robinson Equation State for Prediction of Gas Adsorption Isotherm

This research proposes a modified two-dimensional Peng-Robinson equation model to predict adsorption isotherm in adsorbate-adsorbent systems. The parameters of the proposed model are calculated by using the optimization of experimental data for the different single gas adsorption systems at various temperatures. The experimental adsorption equilibrium data of adsorbate-adsorbent systems was compared with the calculated results in our proposed model and the two-dimensional Hill-deBoer equation model. The proposed model as indicated in the results shows a better prediction of the experimental results compared with two others.

Improved hidden Markov model for speech recognition and POS tagging

In order to overcome defects of the classical hidden Markov model (HMM), Markov family model (MFM), a new statistical model was proposed. Markov family model was applied to speech recognition and natural language processing. The speaker independently continuous speech recognition experiments and the part-of-speech tagging experiments show that Markov family model has higher performance than hidden Markov model. The precision is enhanced from 94.642% to 96.214% in the part-of-speech tagging experiments, and the work rate is reduced by 11.9% in the speech recognition experiments with respect to HMM baseline system.

Novel approach for determining the optimal axial preload of a simulating rotary table spindle system

This paper presents a new theoretical model to determine the optimal axial preload of a spindle system, for challenging the traditional method which relies heavily on experience of engineers. The axial preloading stiffness was treated as the sum of the spindle modal stiffness and the framework elastic stiffness, based on a novel concept that magnitude of preloads can be controlled by measuring the resonant frequency of a spindle system. By employing an example of a certain type of aircraft simulating rotary table, the modal stiffness was measured on the Agilent 35670A Dynamic Signal Analyzer by experimental modal analysis. The equivalent elastic stiffness was simulated by both finite element analysis in ANSYS? and a curve fitting in MATLAB?. Results showed that the static preloading stiffness of the spindle was 7.2125×107 N/m, and that the optimal preloading force was 120.0848 N. Practical application proved the feasibility of our method.

Remote Control and Telemetry System for Large-scale Model Test at Sea

Physical testing of large-scale ship models at sea is a new experimental method.It is a cheap and reliable way to research the environment adaptability of a ship in complex and extreme wave conditions.It is necessary to have a stable experimental system for the test.Since the experimental area is large, a remote control system and a telemetry system are essential, and were designed by the authors.An experiment was conducted on the Songhuajiang River to test the systems.The relationship between the model's speed and its electromotor's revolutions was also measured during the model test.The results showed that the two systems make it possible to carry out large-scale model tests at sea.

Experimental measurement and thermodynamic modeling of binary and ternary solid–liquid phase equilibrium for the systems formed by L-arabinose,D-xylose and water

Solid–liquid phase equilibrium data for binary(L-arabinose–water) and(D-xylose–water) systems at temperatures from(269.85–298.05) K and ternary(L-arabinose–D-xylose–water) system at temperatures of 273.85 K,278.85 K and 284.45 K were measured at atmospheric pressure.The ternary phase diagrams of the systems were constructed on the base of the measured solubility.Two pure solid phases were formed at given temperatures,including pure L-arabinose and pure D-xylose,which were con firmed and determined by the method of Schreinemakers' wet residue.At the same temperature,the crystallization region of L-arabinose was larger than D-xylose's.The acquired solubility data were then correlated using the NRTL model,Wilson model and Xu model.The calculated solubility with the three models agreed well with the experimental values.

Comparison of Models for GPS Kinematic Data Processing

The characteristics of three GPS kinematic data processing models, Least Squares （LS）, Kalman filtering and filtering are discussed and their advantages and disadvantages are compared. With observational data and pertinent data processing software, the applicable condition, context and effect of the three models are experimented. Results show that when the mobile platform is in uniform motion, the accuracy of the three models are almost equal; when the mobile platform is in stochastic acceleration, the accuracy of H∞ filtering model is superior to that of LS, while that of Kalman filtering is the worst.

Vibration Control of Jacket Platforms with Magnetorheological Damper and Experimental Validation~

Magnetorheological （MR） dampers have been proposed to control the vibration of offshore platforms in this paper. The semi-active control strategy based on fuzzy control algorithm was adopted to determine the optimal output control force based on the responses of jacket platforms. A typical jacket platform in Mexico Gulf was selected as the numerical example to investigate the effectiveness of the proposed control method. Furthermore, a model experiment was performed to validate the results of the numerical simulation. The experimental model of the jacket platform was designed based on dynamical similarity criterion by the scale of 1：50. Both of the numerical and experimental results show that the semi-active control system with the MR damper can reduce vibrations of jacket platforms effectively and at the same time the control effect is stable.

The Effects of Flexible Vegetation on Forces with a Keulegan- Carpenter Number in Relation to Structures Due to Long Waves

Extreme coastal events require careful prediction of wave forces. Recent tsunamis have resulted in extensive damage of coastal structures. Such scenarios are the result of the action of long waves on structures. In this paper, the efficiency of vegetation as a buffer system in attenuating the incident ocean waves was studied through a well controlled experimental program. The study focused on the measurement of forces resulting from cnoidal waves on a model building mounted over a slope in the presence and absence of vegetation. The vegetative parameters, along with the width of the green belt, its position from the reference line, the diameter of the individual stems as well as the spacing between them, and their rigidity are varied so as to obtain a holistic view of the wave-vegetation interaction problem. The effect of vegetation on variations of dimensional forces with a Keulegan-Carpenter number （KC） was discussed in this paper. It has been shown that when vegetal patches are present in front of structure, the forces could be limited to within F＊≤I, by a percentile of 92%, 90%, 55%, and 96%, respectively for gap ratios of 0.0, 0.5, 1.0, and 1.5. The force is at its maximum for the gap ratio of 1.0 and beyond which the forces start to diminish.

Measurement and calculation of solubility of quinine in supercritical carbon dioxide

Solubility of quinine in supercritical carbon dioxide(SCCO_2) was experimentally measured in the pressure range of 8 to 24 MPa, at three constant temperatures: 308.15 K, 318.15 K and 328.15 K. Measurement was carried out in a semi-dynamic system. Experimental data were correlated by iso-fugacity model(based on cubic equations of state, CEOS), Modified Mendez–Santiago–Teja(MST) and Modified Bartle semi-empirical models. Two cubic equations of state: Peng–Robinson(PR) and Dashtizadeh–Pazuki–Ghotbi–Taghikhani(DPTG) were adopted for calculation of equilibrium parameters in CEOS modeling. Interaction coefficients(k_(ij)& l_(ij)) of van der Waals(vdW) mixing rules were considered as the correlation parameters in CEOS-based modeling and their contribution to the accuracy of model was investigated. Average Absolute Relative Deviation(AARD) between correlated and experimental data was calculated and compared as the index of validity and accuracy for different modeling systems. In this basis it was realized that the semi-empirical equations especially Modified MST can accurately support the theoretical studies on phase equilibrium behavior of quinine–SCCO_2 media. Among the cubic equations of state DPGT within two-parametric vd W mixing rules provided the best data fitting and PR within one-parametric vd W mixing rules demonstrated the highest deviation respecting to the experimental data. Overall, in each individual modeling system the best fitting was observed on the data points attained at 318 K, which could be perhaps due to the moderate thermodynamic state of supercritical phase.

Lower fuel consumption model and air-flow segregation feeding system for sintering

In order to utilize the spontaneous accumulation of heat (SAH) reasonably and obtain the high quality sinter with low energy consumption, a lower fuel consumption modeling based on raw materials of a certain steel works was built. An air-flow segregation feeding (ASF) experimental equipment was designed to simulate strand feeding process and calculate the lower fuel consumption quantity. Compared with baseline test, the ASF experimental equipment was adopted. The results of sinter pot tests show that the solid fuel consumption is lower than that in baseline test, which is decreased by 5.8%. Meanwhile, other sinter indexes, such as pan yeild, tumbler strength and strand productivity are improved. The mineralogical examination indicates that the mineral compositions and micostructures are improved in sinter.

Bubble Pump Models Verification Based on the Experimental Results

DAR （diffusion absorption refrigeration） cycle is driven by heat and has no moving parts. It is based on refrigerant and absorbent as the working fluid together with hydrogen as an auxiliary inert gas. To circulate the working fluid without a mechanical pump, the diffusion absorption cycle relies on a bubble pump. Experimental system was designed and operated. Its aim was to investigate the performance of a bubble pump operating with three lifting tubes. The experimental results of the system were compared to existing models. The comparison showed that there was a bad agreement between the experimental and the theoretical results.

PPP项目再谈判触发事件验证研究

合同的不完备性及PPP项目的长期性致使PPP再谈判必然存在.为探究各因素影响PPP项目再谈判的程度,以及如何从主要制约因素入手优化PPP项目的再谈判起因与再谈判过程,基于不完备合同理论,通过文献研究确定合同核心要素,构建层次结构模型;采用DEMATEL模型确定核心要素中各指标的逻辑关系并构造出其直接影响矩阵.通过改进的AHP-DEMATEL方法,综合考虑层次结构模型的纵向及横向影响,计算综合权重,为合同条款注入再谈判的设计提供依据和重点.

Effects of crop species richness on pest-natural enemy systems based on an experimental model system using a microlandscape

The relationship between crop richness and predator-prey interactions as they relate to pest-natural enemy systems is a very important topic in ecology and greatly affects biological control services.The effects of crop arrangement on predator-prey interactions have received much attention as the basis for pest population management.To explore the internal mechanisms and factors driving the relationship between crop richness and pest population management,we designed an experimental model system of a microlandscape that included 50 plots and five treatments.Each treatment had 10 repetitions in each year from 2007 to 2010.The results showed that the biomass of pests and their natural enemies increased with increasing crop biomass and decreased with decreasing crop biomass;however,the effects of plant biomass on the pest and natural enemy biomass were not significant.The relationship between adjacent trophic levels was significant(such as pests and their natural enemies or crops and pests),whereas non-adjacent trophic levels(crops and natural enemies) did not significantly interact with each other.The ratio of natural enemy/pest biomass was the highest in the areas of four crop species that had the best biological control service.Having either low or high crop species richness did not enhance the pest population management service and lead to loss of biological control.Although the resource concentration hypothesis was not well supported by our results,high crop species richness could suppress the pest population,indicating that crop species richness could enhance biological control services.These results could be applied in habitat management aimed at biological control,provide the theoretical basis for agricultural landscape design,and also suggest new methods for integrated pest management.

Study on the critical submergence of surface vortices and the design of anti-vortex intakes

Surface vortex behavior in front of the tunnel intake was investigated in this paper.The critical submergence of vortex was discussed based on the concept of 'critical spherical sink surface'(CSSS).The vortex formation and evolution at the tunnel intake were analyzed based on the theory of CSSS considering the effect of circulation.A theory was proposed to explain the surface vortex.The theoretical development was verified by the physical model experiments of Xiluodu hydropower station.The radial velocity and vortex circulation were considered as the main factors that influence the formation and evolution of surface vortex.Finally,an anti-vortex intake configuration was proposed to weaken the air-core vortex in front of the tunnel intakes of the hydraulic structures.