基于GA-GRNN的高速列车头型三维优化设计

针对CRH380A型高速列车头部外形的气动减阻问题, 设计了一种新型的基于自由曲面变形的局部型函数参数化方法, 提出了一套基于实数编码遗传算法的变光滑因子广义回归神经网络响应面模型(GA-GRNN)的气动外形优化方法. 优化结果表明: 局部型函数参数化方法操作简单、实现方便, 使用少量的设计参数可以控制较大变形区域, 且能保证变形的光顺性和不同变形区域间的光滑过渡; 使用同样的样本点进行训练, GA-GRNN 比GRNN的预测精度高, 更容易得到全局最优解; 优化后, CRH380A 三辆编组简化外形气动阻力减小8.7%, 本文提出的优化设计方法简单、高效, 为高速列车气动外形的工程优化设计提供了新思路

国内高速列车气动噪声研究进展概述

随着运行速度的提升,气动噪声逐渐成为高速列车最主要的噪声源,并极有可能成为新设计高速列车的一个技术瓶颈。开展高速列车气动噪声研究,明晰高速列车气动噪声机理与规律,发展低噪声高速列车外形设计对更高速度级的高速列车研发具有重要意义。本文主要对自2010年以来国内进行的高速列车气动噪声研究进行梳理总结。首先详细介绍了高速列车气动噪声研究采用的一系列方法,主要从实车试验、风洞实验以及数值模拟方法三个方面展开。在掌握高速列车气动噪声研究方法的基础上,进而探讨了当前高速列车气动噪声研究的现状,重点就高速列车气动噪声源识别、主要噪声源机理与特性、噪声源优化等方向进行了阐述,并明确了当前研究获得的一些主要结论。最后简要探讨了高速列车气动噪声未来可能的研究方向

Characterization and application of nucleocapsid protein of porcine reproductive and respiratory syndrome virus expressed in E.coli

从已构建的PRRSV ORF7重组质粒pUCm-T-ORF7中用PCR扩增ORF7基因亚克隆至表达载体pGEX-4T-3,构建重组表达质粒pGEX-4T-3-ORF7并转化大肠杆菌。经SDS-PAGE及Western blotting鉴定,成功表达了谷胱苷肽转移酶(GST)融合的核衣壳蛋白(N),重组N蛋白表达量约为菌体总蛋白的35%,主要以可溶的形式存在,且能形成同源二聚体。重组N蛋白经谷胱苷肽凝胶(glutathione sepharose 4B)亲和层析后得到高度纯化,并将该蛋白作为抗原建立了间接ELISA检测方法。利用该方法对某猪场76份猪血清进行检测并将结果与IDEXX公司ELISA试剂盒检测结果作比较,2种方法的总符合率达93.4%,检测结果之间差异不显著(P>0.05)。结果表明大肠杆菌表达的重组GST融合N蛋白具有良好的抗原性,因而有望利用该重组蛋白开发为试剂盒应用于临床PRRSV抗体的检测。Porcine reproductive and respiratory syndrome virus(PRRSV) FJ-1 was a newly identified virus isolate in Fujian province.The ORF7 gene of FJ-1 was amplified by RT-PCR and cloned into vector pUCm-T,then subcloned into expression vector of pGEX-4T-3.The recombinant GST-tagged nucleocapsid protein(rN) was expressed in E.coli and the molecular weight was approximately 38 000 as identified by SDS-PAGE and Western blotting.Expression level of the rN protein was approximately 35% of the total bacterial protein and mostly soluble.The rN protein was purified to homogeneity using GST affinity chromatography.Analysis of the rN protein under nonreducing conditions revealed that similar to native protein,the rN protein also possesses homo-dimerization property.An indirect enzyme-linked immunosorbent assay(ELISA) for detecting PRRSV antibody was developed using the purified rN protein as antigen.76 serum samples were detected by the method and the result was compared with that using IDEXX PRRS HerdChek ELISA kit.An identity of 93.4% was revealed between the two ELISA kits and no significant difference(P>0.05) was detected.The data indicate the rN protein has the potential usefulness for detection of the PRRSV antibodies.福建省科技攻关计划重点资助项目(2003N083);; 厦门市科技攻关计划重点资助项目(3502Z20031054

典型路基结构对高速列车横风气动特性影响分析

由于地域及环境的限制, 高速铁路采用多种路基结构如平直地面、不同高度路堤、高架桥等,当列车运行在路堤及高架桥上时,车体周围的绕流流场比平直地面更加复杂。在强横风的作用下,不同的路基结构上的高速列车横风气动特性存在明显差异,不合理的路基结构将影响列车的横风安全性。同时列车结构复杂,转向架、受电弓等都对列车的流场特性有重要作用,过于简化的短编组列车外形不能够精细反映列车的真实气动特性。为研究典型路基结构对高速列车横风气动特性的影响,以9编组动力集中型高速列车实车为研究对象,考虑风挡、转向架、受电弓等细节特征,对列车运行速度为200 km/h,横风速度分别为20 m/s、30 m/s、35 m/s、40 m/s,路基结构分别为平直地面、3 m路堤、6 m路堤、高架桥等四种场景下的高速列车空气动力学性能进行了仿真计算和对比,分析了不同路基地面条件下列车的横风气动特性的差异及规律,为横风条件下复杂路基结构的列车运行安全控制提供了参考

Comparison of Luminous Efficiency of InGaN-based High-voltage LED with Traditional High Power LED

主要从三个不同角度探究并分析了基于In gA n材料的高压lEd的发光效率优于传统大功率lEd的原因。为了保证实验结论的可靠性,文中所采用的实验样品具有相同的芯片尺寸和材料以及相同的封装结构。经过大量的实验证明,更均匀的电流分布和小芯片间隙的出光,使得高压lEd的发光效率优于传统大功率lEd。结果显示,在相同的1 W输入功率下,高压lEd的发光效率比传统大功率lEd高大约4.5%。The reasons of the luminous efficiency of In Ga N-based high-voltage light-emitting diode(HV-LED)better than that of traditional high power(THP) LED are researched and analyzed from three different aspects.Theexperimental sample with same chip size, material and package structure is adopted to ensure the reliability of ex-periment conclusions.Experiments show that the luminous efficiency of HV-LED is better than that of THP LED foruniformer current distribution and the light from the microchip gap.The results show that the luminous efficiency ofHV-LED is approximately 4.5% higher than that of THP-LED under 1 W input power.国家863项目(2013AA03A107); 福建省产学研重大科技项目(2013H6024); 福建省重点科技项目(2012H0039)资

Design of a Temperature-Controlled Test System for Luminous Intensity Spatial Distribution Characteristics of High Power LED

发光二极管(lEd)的光强空间分布特性决定了它能否满足特定场合的应用。大功率lEd由于发热量大,其绝对光强空间分布(lISd)的测试也必须在特定热沉温度下进行才能得到准确可靠的结果。设计了一个可对大功率lEd进行热沉温度控制且快速实现lISd自动测试的系统。该自动测试系统基于lEdgOn-100测角光度计及其高精度的二维旋转台,配合测试适配器、温度控制器、光度探头、kEITHlEy 2400源表和测试软件组成。测试软件基于dElPHI程序语言开发。在控温条件下,该lISd自动测试系统稳定可靠,测试时间大大缩短,测试结果实时直观。利用该自动测试系统对具有朗伯型和蝙蝠翼型两大lISd类型的lEd进行测试,获得它们的二维lISd和三维lISd。实验结果表明:随着热沉温度的增加,光强绝对值下降,而相对lISd却不变。Characteristics of the luminous intensity spatial distribution(LISD) of light emitting diodes(LEDs) are capable of determining whether these devices can be applied on specific occasions.The absolute LISD of high power LED can be accurately measured only when LED is fixed at a specific heat- sink temperature because of the LED′s large heat-generating capacity.In this study, an automatic test system based on LEDGON-100 goniophotometer and the meter′s high-precision two-dimensional(2D) revolving platform, is designed.In addition, it comprises of a test adapter, a temperature controller, a photometer head, a Keithley 2400 source meter, and an in-house-developed software package.This assembly can both control heat-sink temperatures and measure the LISD characteristics rapidly for high- power LEDs.The software is developed using Delphi programming language.The test system is stable and reliable.The test time is greatly reduced and measurements are instantly displayed.Two general types of LEDs, Lambertian type and batwing type, are measured by the system to obtain their 2D and three-dimensional(3D) LISDs.Experimental results show that the absolute luminous intensity decreases as the heat-sink temperature increases.However, the relative LISDs are the same under different heat-sink temperatures.国家自然科学基金(11104230); 福建省重大科技项目(2011H6025;2012H0039

Influences of affiliated components and train length on the train wind

The induced airflow from passing trains, which is recognized as train wind, usually has adverse impacts on people in the surroundings, i.e., the aerodynamic forces generated by a high-speed train&#39;s wind may act on the human body and endanger the safety of pedestrians or roadside workers. In this paper, an improved delayed detached eddy simulation (IDDES) method is used to study train wind. The effects of the affiliated components and train length on train wind are analyzed. The results indicate that the affiliated components and train length have no effect on train wind in the area in front of the leading nose. In the downstream and wake regions, the longitudinal train wind becomes stronger as the length of the train increases, while the transverse train wind is not affected. The presence of affiliated components strengthens the train wind in the near field of the train because of strong flow solid interactions but has limited effects on train wind in the far field.</span

Investigation of the origin and evolution of groundwater in Yang-Dai River Plain by chlorine,oxygen 18 and deuterium

通过分析地表水和地下水中氯离子浓度和δd、δ18O值的空间分布特征,揭示了秦皇岛洋戴河平原地下水的形成演化规律.结果发现,洋戴河平原地表河水来源于中上游水库水和大气降水的混合,且河水沿程受到δd、δ18O值、氯离子浓度更低的支流或灌渠水补给,从而使δd、δ18O值、氯离子浓度呈现沿程逐渐降低的现象.山前丘陵区地下水主要接受大气降水的直接补给,洪积扇及山麓地带地下水受到了一定的蒸发作用影响,除了接受丘陵区地下水的侧向补给外,洋河附近地下水还受到洋河水库水的混合.研究区西部咸水带的地下水由上游地下水和大泥河地热咸水混合而成,地热咸水的混合比率约为13%,而东部咸水带的地下水由上游地下水、本地污水和地热咸水混合而成,地热咸水的混合比率不超过9%.在海水入侵区,地下水主要由本区地下淡水和海水(海水混合比率不超过10%)混合而成,并且受到了不同程度的地表水或农田灌溉水的补给,其中,浦河一带是地表水或灌溉水补给较为明显的地段.The aim of this paper is to reveal the origin and evolution of surface water and groundwater by analyzing the spatial distribution of chloride ion concentration and δD and δ18O values in surface water and groundwater in Yang-Dai River Plain.The Yang-Dai River originates from the mixing of water of reservoir and meteoric water,and river water is also from the recharge in the tributary and irrigation ditch which have much lower chloride ion concentration and δD and δ18O values.Therefore,chloride ion concentration and δD and δ18O values in river water decreases gradually from upstream to downstream.The groundwater in hilly area is primarily recharged by meteoric water,and the groundwater in pluvial fan and piedmont experiences evaporation partly.The groundwater in pluvial fan and piedmont is recharged not only laterally by upstream groundwater from mountainous and hilly area,but also by Yang River reservoir water.In the study area,the groundwater in the west part of salty water region is mixed between upstream groundwater and salty geothermal water originated from Danihe area,with a mixing radio of 13% salty geothermal water.In comparison,the groundwater in the east part of salty water region is mixed by upstream groundwater,sewage water and salty geothermal water,with a mixing radio of up to 9% salty geothermal water.In the seawater intrusion region,the groundwater was mainly constituted of local fresh groundwater and intrusive seawater with a mixing ratio of up to 10% seawater,and is also partly recharged by surface water and agricultural irrigation water which have higher contribution to the groundwater recharge in Pu River area.国家重点基础研究发展计划(973)项目(No.2010CB428805); 环保公益性行业科研专项经费项目(No.201309006)~

Drag reduction using riblets downstream of a high Reynolds number inclined forward step flow

Micro-riblet is an efficient passive method for controlling turbulent boundary layers, with the potential to reduce frictional drag. In various applications within the transportation industry, flow separation is a prevalent flow phenomenon. However, the precise drag reduction performance of riblets in the presence of flow separation remains unclear. To address this, an inclined forward step model is proposed to investigate the interaction between riblet and upstream flow separation. The large eddy simulation (LES) method is applied to simulate the flow over geometries with different step angles and riblet positions. The results show riblets still reduce wall frictional resistance when subjected to the upstream flow separation. Remarkably, as the angle of the step increases from 0 degrees to 30 degrees, the drag reduction experiences an increment from 9.5% to 12.6%. From a turbulence statistics standpoint, riblets act to suppress the Reynold stress in the near-wall region and dampen ejection motions, thus weakening momentum exchange. Quadrant analysis reveals that with the augmentation of flow separation, the Q2 motion within the flow field intensifies, subsequently enhancing the riblet-induced drag reduction. Moreover, the position of the rib lets has a significant impact on the pressure drag. Riblets close to the point of separation enhance flow separation, altering the surface pressure distribution and thus increasing the resistance. The results reveal that when the riblets are positioned approximately 160 riblet heights away from the step, their effect on the upstream flow separation becomes negligible. The precise performance of riblets under complex flow conditions is important for their practical engineering application

Parametric design and optimization of high speed train nose

Aiming at shortening the design period and improve the design efficiency of the nose shape of high speed trains, a parametric shape optimization method is developed for the design of the nose shape has been proposed in the present paper based on the VMF parametric approach, NURBS curves and discrete control point method. 33 design variables have been utilized to control the nose shape, and totally different shapes could be obtained by varying the values of design variables. Based on the above parametric method, multi-objective particle swarm algorithm, CFD numerical simulation and supported vector machine regression model, multi-objective aerodynamic shape optimization has been performed. Results reveal that the parametric shape design method proposed here could precisely describe the three-dimensional nose shape of high speed trains and could be applied to the concept design and optimization of the nose shape. Besides, the SVM regression model based the multi-points criterion could accurately describe the non-linear relationship between the design variables and objectives, and could be generally utilized in other fields. No matter the simplified model or the real model, the aerodynamic performance of the model after optimization has been greatly improved. Based on the SVR model, the nonlinear relation between the aerodynamic drag and the design variables is obtained, which could provide guidance for the engineering design and optimization