列流线偏移描绘自动化

基于图论理论分析了列流图的组成特性,以解决列流线折点自动搜索问题.提出列流线折点搜索算法和列流线偏移描绘算法.采用基于节点信息表绘制列流图.开发了列流图自动生成数据库系统.用实例表明了算法及软件有效性和可行性.

列流图中列流线生成与排序优化算法

针对列流线铺画中枢纽车站数量多、车站衔接方向多以及列车种类多等现实难题,提出列流线生成与排序优化算法,实现列流图的快速铺画。根据列流图“横平竖直”的表现形式,按线路经纬向分割同一方向衔接多条线路的车站,作为后续算法的基础;基于双向扫描算法思想,构建列流线路径的优化生成算法,在任意车站对之间生成列流线备选集合,通过人机交互方式快速确定列流线径路;以列流线交叉点最少兼顾中心对称为优化目标,提出列流线排序优化算法,快速确定列流线在沿途各区间及车站内的空间相对位置。基于列流线生成与排序优化算法开发列流图优化编制辅助设计系统,并以金华铁路枢纽为例进行验证。结果表明:生成列流图无列流径路以及数据标识错误,且列流线备选集合生成以及列流线排序的时间消耗均小于1 s,列流线生成与排序优化算法具有合理性与有效性。

大型复杂枢纽列流图的列流线排列优化算法

根据铁路枢纽内车站、铁路线之间的拓扑关系,以及车站衔接方向节点间的横纵坐标关系,提出通道到发节点对集合概念和求解算法。针对车站衔接的铁路线多的新特点,根据列流线在车站对应的到达节点和出发节点之间的相互关系,提出列流线直行最内侧、始发最外侧、终到最外侧、到达节点“逆时针”和出发节点“顺时针”6条排列原则。基于列流线沿铁路线和通道内排列关系不变的2个假定条件,提出“通道法”排列优化思路,构建列流线排列优先权重求解算法和排列优化算法。以包含23座车站、衔接13个方向的上海铁路枢纽为例,对68条列流线进行排列优化,验证了算法的合理性和有效性。

Numerical investigation on the aerodynamic drag reduction based on bottom deflectors and streamlined bogies of a high-speed train

The complex structure of the bottom of a high-speed train is an important source of train aerodynamic drag.Thus,improving the bottom structure is of great significance to reduce the aerodynamic drag of the train.In this study,computational fluid dynamics(CFD)based on three-dimensional steady incompressible Reynolds-average Naiver-Stokes(RANS)equations and Realizable k-ε turbulence model were utilized for numerical simulations.Inspired by the concept of streamlined design and the idea of bottom flow field control,this study iteratively designed the bogies in a streamlined shape and combined them with the bottom deflectors to investigate the joint drag reduction mechanism.Three models,i.e.,single-bogie model,simplified train model,and eight-car high-speed train model,were created and their aerodynamic characteristics were analyzed.The results show that the single-bogie model with streamlined design shows a noticeable drag reduction,whose power bogie and trailer bogie experience 13.92%and 7.63%drag reduction,respectively.The range of positive pressure area on the bogie is reduced.The aerodynamic drag can be further reduced to 15.01%by installing both the streamlined bogie and the deflector on the simplified train model.When the streamlined bogies and deflectors are used on the eight-car model together,the total drag reduction rate reaches 2.90%.Therefore,the proposed aerodynamic kit for the high-speed train bottom is capable to improve the flow structure around the bogie regions,reduce the bottom flow velocity,and narrow the scope of the train’s influence on the surrounding environment,achieving the appreciable reduction of aerodynamic drag.This paper can provide a new idea for the drag reduction of high-speed trains.

Multi-objective optimization of the streamlined head of high-speed trains based on the Kriging model

As the running speed of high-speed trains increases, aerodynamic drag becomes the key factor which limits the further increase of the running speed and energy consumption. Aerodynamic lift of the trailing car also becomes the key force which affects the amenity and safety of the train. In the present paper, a simplified CRH380A high-speed train with three carriages is chosen as the model in order to optimize aerodynamic drag of the total train and aerodynamic lift of the trailing car. A constrained mul- ti-objective optimization design of the aerodynamic head shape of high-speed trains based on adaptive non-dominated sorting genetic algorithm is also developed combining local function three-dimensional parametric approach and central Latin hypercube sampling method with maximin criteria based on the iterative local search algorithm. The results show that local function parametric approach can be well applied to optimal design of complex three-dimensional aerodynamic shape, and the adaptive non-dominated sorting genetic algorithm can be more accurate and efficient to find the Pareto front. After optimization the aerodynamic drag of the simplified train with three carriages is reduced by 3.2%, and the lift coefficient of the trailing car by 8.24%, the volume of the streamlined head by 2.16%; the aerodynamic drag of the real prototype CRH380A is reduced by 2.26%, lift coefficient of the trailing car by 19.67%. The variation of aerodynamic performance between the simplified train and the true train is mainly concentrated in the deformation region of the nose cone and tail cone. The optimization approach proposed in the present paper is simple yet efficient, and sheds lights on the constrained multi-objective engineering optimization design of aerodynamic shape of high-speed trains.

Facility Layout Based on Sequence Analysis:Design of Flowshops

A computer-aided method to design a hybrid layout--tree-shape planar flowlines is presented. In newtype fiowshop layout, the common machines shared by several flowlines could be located together in functional sections. The approach combines traditional cell formation techniques with sequence alignment algorithms. Firstly, a sequence analysis based cell formation procedure is adopted; then the operation sequences for parts are aligned to maximize machines adjacency in hyperedge representations; finally a tree-shape planar flowline will be obtained for each part family. With the help of a sample of operation sequences obtained from industry, this algorithm is illustrated.

Convective Assembly of Linear Gold Nanoparticle Arrays at the Micron Scale for Surface Enhanced Raman Scattering

A convective assembly technique at the micron scale analogous to the writing action of a ＂pipette pen＂ has been developed for the linear assembly of gold nanoparticle strips with micron scale width and millimeter scale length for surface enhanced Raman scattering （SERS）. The arrays with interparticle gaps smaller than 3 nm are hexagonally stacked in the vicinity of the pipette tip. Variable numbers of stacked layers and clean surfaces of the assembled nanoparticles are obtained by optimizing the velocity of the pipette tip. The SERS properties of tile assembled nanoparticle arrays rely on their stacking number and surface cleanliness.

Growth and magnetic properties of single crystalline Ni nanowire arrays prepared by pulse DC electrodeposition

Highly textured Ni nanowire arrays were fabricated into anodic aluminum oxide （AAO） templates by pulse DC electrodeposi- tion. The applied voltage and pH value of electrolytes were found strongly affecting the microstrucmre and magnetic proper ties of Ni nanowire arrays. Low applied potential and pH value both prefer to form polycrystalline fcc Ni nanowires. Increas- ing the applied potential or pH value favors the Ni [220] texture and even eventually forms the [220] oriented single crystal Ni wires, while exorbitant potential and pH value will conversely weaken the texture of nanowires. The magnetic properties of Ni wires are closely related to the microstructure of Ni nanowire arrays and large coercivities more than 1000 Oe were achieved at single crystalline Ni nanowire arrays. The mechanisms for the effect of applied potential and pH value on the grain size, tex- ture and magnetic properties of Ni nanowire arrays have been discussed.

Integration of microfluidic injection analysis with carbon nanomaterials/gold nanowire arrays-based biosensors for glucose detection

Carbon nanotubes(CNTs) and reduced graphene oxide(r GO) nanosheets were utilized to construct glucose biosensors in combination with gold nanowire arrays(Au NWAs), and microfluidic injection analysis driven by gravity force was used to investigate the performances of as-prepared glucose biosensors. The results demonstrated glucose biosensors based on carbon nanomaterials/Au NWAs presented excellent performance at low working potential of-0.2 V versus Ag/Ag Cl(3 mol/L KCl), such as high sensitivity, good anti-interference ability and high throughput(45 h^(-1)). The glucose biosensor based on glucose oxidase(GOx)–CNT–Au NWAs showed a wide linear range from 100 to 3,000 lmol/L with a sensitivity of 4.12 l A/cm^2 mmol/L. Furthermore, the linear range and sensitivity of GOx–r GO–Au NWAs-based glucose biosensor were 50–4,000 lmol/L and 8.59 l A/(cm^2 mmol/L), respectively, which were better than those of glucose biosensor based on GOx–CNT–Au NWAs,suggesting r GO nanosheets in combination with Au NWAs being a good platform for the construction of glucose biosensors.