Quickbird影像在城市三维中应用

由于Quickbird影像的多光谱影像的波段齐全,与高分辨率影像融合之后得到的影像色彩比较接近地物的真实颜色,使得信息丰富、同时影像的现时性强,是我们在城市三维建设中的重要数据源。本文利用Quickbird影像通过融合后用于建立地表模型和提取地物特征信息数据,实现城市三维重建。     

基于形状特征的线状地物提取方法研究

遥感影像上线状地物的提取是影像处理的主要研究内容之一。通过对线状地物形状特征的分析,将其抽象为长矩形,设定长宽比阈值,进行线状地物提取,取得不错实验结果。     

一种高分辨率城区遥感影像分割方法

高分辨率遥感影像具有丰富的地物细节信息。本文将均值漂移算法应用到高分辨率城市区域遥感影像的分割中,并对其实验结果进行了分析,为下一步的研究提供理论支持。     

基于模糊聚类分析下达斡尔族传统工艺色彩的提取

本文以分类收集整理即将遗失相关达斡尔族的文化和传统工艺色彩,通过相关文献、影像资料进行研究,抽象选取达斡尔传统工艺色彩—单体器物色彩的RGB色彩模型和人眼识别图像作为研究样本、以特征提取数据实现色彩的量化、构造色彩信息数据库、并以各类色彩提取样本信息归类。运用模糊聚类对其色彩复杂度进行分析,验证其方法具有较高的聚类精度。     

新型航空遥感三维成像

航空遥感技术已经有几十年的发展历程,其中应用最为广泛的是航空摄影。航空摄影是采用高分辨率的感光胶片记录地面上各种地物目标影像。人们获取这些地物目标影像的目的并不是为了欣赏地球的美貌,而是通过航空影像全面地获取有关区域内的地面地物目标信息,特别是通过航空影像来测绘精确地形图,以满足国防及经济建设的需要。从航空照片影像获取地物目标空间数据信息及测绘地形图,必须建立航空照片影像与所对应的地面地物目标之间的严密的数学关系,这叫做航空照片的对地定位。只有经过定位的航空照片影像,丰富的信息影像才能够成为有实…     

基于角度纹理特征模型的道路提取方法

随着遥感影像分辨率不断提高,影像上地物目标特征也相对复杂,目前道路提取算法通用性和稳定性都减弱,复杂的模型提取效率较低。本文提出一种基于角度纹理特征模型提取道路中心线．并同时获取道路的宽度信息,实验数据采用高空间分辨率全色卫星影像,实验表明：该算法是一种有效地道路提取方法．提取结果能够满足遥感测绘作业要求,为道路提取和更新提供一种智能化手段。     

辅以波谱分析的高分辨率影像面向对象分类研究

随着遥感影像空间分辨率的提高,地物的空间信息更加丰富,地物尺寸、形状以及相邻地物的关系得到更好的反映,因此目前高分辨率影像分类方法更侧重于利用地物的空间信息,分类过程中参与较多的人为主观因素,在地物类型未知的地区很难进行解译工作。另外,分割过于细碎导致操作数据量太大也是高分辨率影像分类的难题之一。论文提出了辅以波普分析的高分辨率影像面向对象分类方法,即在传统面向对象分类方法的基础上结合影像波谱分析,先对影像光谱角制图粗分类、掩膜操作,再面向对象精分类,较好解决了以往面向对象分类方法地物类型的不确定性和分割细碎等问题。试验以空间分辨率为0.5米的八波段WorldView2影像为研究数据提取西部那曲地区道路和河流,精度达到96.36%。     

浅谈地质找矿中的遥感技术

随着遥感技术的推广,遥感地质技术人员不断在实践中总结和提高,遥感技术的应用程度日臻成熟,地质的许多方向都有了不同程度的发展。遥感影像可以全面、客观地记录地表综合景观的几何特征,遥感图像不仅可以获得地表景观的形态、分布特征组合,而且还可以获得物质的成分和结构等,进而实现地物识别的目的。遥感技术在地质找矿中的应用包括直接应用和间接应用:直接应用是指遥感蚀变信息的提取,间接应用则包括地质构造信息、植被的光谱特征及矿床改造信息等方面。     

基于移动终端的色彩信息交互式即时提取技术

目的基于移动终端以交互式获取的图像,即时提取其色彩构成信息并用于配色设计。方法通过聚类技术对单幅图像的像素值和多幅图像的提取色进行二次聚类,得到综合提取色。用户可选择灰度优先和色相优先这两种色彩提取方式,并指定提取色的数量,为用户提供综合提取色的各色彩分量值以及每种色彩所占比例。然后对苗绣图案进行技术应用验证。结论为设计师产品配色设计的图像灵感来源提供了快速处理技术,并开发了随机配色和基于色彩比例的概率配色这两种后期图案自动配色技术,显著提高了设计师的工作效率。     

基于非监督分类的遥感信息提取方法尝试

随着遥感技术的发展,遥感数据已应用到很多领域。从遥感影像中分析出地物空间特征和属性特征是遥感影像解译的关键。遥感图像分类是将图像中每个像元根据其在不同波段的光谱亮度、空间结构特征或其他相关信息,按照一定的规则或算法划分为不同的类别。利用非监督分类法尝试对ETM+遥感影像进行分析解译,提取水体专题信息,从结果来看专题信息提取效果较好。     

实测端元光谱和多光谱图像之间的模拟与细分

地物光谱特性是遥感应用的基础。本文以渭干河-库车河三角洲绿洲为研究区,首先选取裸土、植被两类地物作为研究对象,通过TM传感器的光谱响应函数,实现了将野外实测端元光谱拟合为多光谱离散光谱。其次在对TM图像的光谱波段进行细分的基础上,利用光谱知识库的数据支持来模拟获取具有更高光谱分辨率的细分光谱光学遥感图像,深入开展两种尺度相互转换的研究。结果表明:一、拟和的多光谱与TM像元光谱具有很好的相关性,在此基础上,采用线性算法建立端元光谱与遥感图像像元光谱的转换模型,实现了从实测端元光谱尺度向遥感多光谱像元尺度的定量光谱转换,为遥感定量分析奠定了一定基础。二、细分光谱模拟图像的方法能够较为可靠的模拟出真实高光谱分辨率图像的信息,模拟方法可信,达到了推广和验证的效果。     

Recent development and prospect of electromagnetic processing of materials

Application of electromagnetic force to materials processing, so called Electromagnetic Processing of Materials (EPM) has been recognized as a cutting edge technology, especially in the fields of advanced materials processing. The backgroundto promote EPMis described. The present state of EPMis given through a brief introduction of several examples of the applications of a high frequency magnetic field, a DC magnetic field, DC magnetic and electric fields, and a traveling magneticfield. Furthermore, a high static magnetic field has been applied to generate compression waves in molten metals. As otherexamples of the application of a high static field, the crystal orientations in thin films in vapordeposition and electrodeposition processes and those in carbon fibers in a graphitization process are described. Finally the future view of EPM is revealed.     

Effect of surface slip on Stokes flow past a spherical particle in infinite fluid and near a plane wall

The motion of a spherical particle in infinite linear flow and near a plane wall, subject to the slip boundary condition on both the particle surface and the wall, is studied in the limit of zero Reynolds number. In the case of infinite flow, an exact solution is derived using the singularity representation, and analytical expressions for the force, torque, and stresslet are derived in terms of slip coefficients generalizing the Stokes–Basset–Einstein law. The slip velocity reduces the drag force, torque, and the effective viscosity of a dilute suspension. In the case of wall-bounded flow, advantage is taken of the axial symmetry of the boundaries of the flow with respect to the axis that is normal to the wall and passes through the particle center to formulate the problem in terms of a system of one-dimensional integral equations for the first sine and cosine Fourier coefficients of the unknown traction and velocity along the boundary contour in a meridional plane. Numerical solutions furnish accurate predictions for (a) the force and torque exerted on a particle translating parallel to the wall in a quiescent fluid, (b) the force and torque exerted on a particle rotating about an axis that is parallel to the wall in a quiescent fluid, and (c) the translational and angular velocities of a freely suspended particle in simple shear flow parallel to the wall. For certain combinations of the wall and particle slip coefficients, a particle moving under the influence of a tangential force translates parallel to the wall without rotation, and a particle moving under the influence of a tangential torque rotates about an axis that is parallel to the wall without translation. For a particle convected in simple shear flow, minimum translational velocity is observed for no-slip surfaces. However, allowing for slip may either increase or decrease the particle angular velocity, and the dependence on the wall and particle slip coefficients is not necessarily monotonic.     

微通道换热器两相流分布研究现状与展望

两相流进入微通道换热器容易出现分布不均匀的现象,显著降低微通道换热器的性能.本文对微通道换热器两相流分布的研究动态进行了归纳与分析,主要介绍了微通道换热器中两相流分布特性的影响因素、提升微通道换热器中两相流分布均匀性的技术方案、微通道换热器两相流分布特性的仿真研究及相分离技术在微通道换热器中的应用;论述了两相流在微通道...     

Safety stock or safety lead time: coping with unreliability in demand and supply

Safety stock and safety lead time are common measures used to cope with uncertainties in demand and supply. Typically, these uncertainties are studied in isolated instances, ignoring settings with uncertainties both in demand and in supply. The current literature largely neglects case study based contexts and, often, single product situations are investigated in which machine set-ups are not considered. Based on the problems and findings in a case study, we investigate the effects of safety stock and safety lead time on delivery performance in a multi-product setting. The outcomes of the extensive simulation study indicate that utilising a safety lead time results in a higher delivery performance where there is a variable supply, whereas having a safety stock results in a higher delivery performance where there is unreliable demand information. In contrast to earlier findings in the single product situation, this study shows that managers facing the combination of unreliability in demand information and supply variability in a multiple product situation should opt for a safety lead time as the most effective way of improving their delivery performance.     

汽车悬架设计概念的研究

近年来在世界汽车工业中，都在努力改进汽车的驾驶稳定性和平顺性。对于这个领域，大家根据经验都知道悬架的影响力最大。然而目前在悬架设计中需要大量的有经验和感觉的设计者。在研究中，推荐了一种新的设计方法，来代替那种靠设计者的经验和感觉的设计方法，这种概念可以用一个简单的方法来定量地评价悬架系统的设计情况。     

An approach to simulate the motion of spherical and non-spherical fuel particles in combustion chambers

The objective of this paper is to identify a numerical method to simulate motion of a packed or fluidized bed of fuel particles in combustion chambers, such as a grate furnace and a rotary kiln. Therefore, the various numerical methods applied in the areas of granular matter and molecular dynamics were reviewed extensively. As a result, a time driven approach was found to be suited for the numerical simulation of particle motion in combustion chambers. Furthermore, this method can also be employed to moving boundaries which are required for the present application e.g. travelling grate. The method works in a Lagrangian frame of reference, which uses the position and orientation of particles as independent variables. These are obtained by time integration of the three-dimensional dynamics equations derived from the classical Newtonian approach for each particle. This includes the keeping track of all forces and momentums acting on each particle at every time step. Viscoelastic contact forces include normal and tangential components with viscoelastic models for energy dissipation and friction. The particle shapes are approximated by spheres and ellipsoids with a varying size and ratio of the semi-axis accounting for the variety of particle geometries in a combustion chamber. For these shapes the overlap of particles during contact is expressed by a polynomial of 4th order in the two-dimensional case and a polynomial of 6th order in the three-dimensional case. A new algorithm to detect two-dimensional elliptical particle contact with sufficient accuracy was developed. It is based on a sequence of coordinate transformations and has demonstrated its reliability in numerous applications. Finally, the method was applied to simulate the motion of spherical and elliptical particles in a rectangular enclosure, on a travelling grate, and in a rotary kiln. Received: 16 November 2001     

Recent trends in design education

This paper gives a brief review of recent trends in design education in schools in the UK. There has been a steady growth over the last decade of a grass-roots development of design education in schools. This has been accompanied by a parallel growth in the study of the implications of design for child learning and pedagogic practice. Significantly, in the last four or five years there has also been a growing interest in these developments amongst academics, industrialists, politicians, and a much wider general audience than teachers and educationalists.     

Statistical Analysis of Macromolecular Chains in the Space Filled by Nanoparticles

The paper presents a combination of worm-like chain numerical models and one with a finite set of nano-particles. The primary objective of the models was to analyze the distribution of space in a system filled by particles. Information on the distribution of space was compared to properties of chains inside the set of particles. The set of nanoparticles was constructed with a tool generating a finite set of particles that is randomly distributed in a given space. The particles have a prescribed volume fraction and uniform size. First, the proportions of chains and particles were compared. The length of chain was expressed in terms of end-to-end length. It was then compared to the size of gaps between two particles. The volume of chain was compared to the volume of space delimited by the particles. Next, a set of 10,000 random chains was generated and these were introduced into the particle set. The contact of a chain with the surface of a particle resulted in the special structural elements of the chain: a chain connecting two different particles, a loop which begins and ends at the same particle, a part of a chain which is completely adhered to the particle surface, a chain attached to a particle with one free end, as well as completely free chains. The chains were classified under three classes: chains which were not in contact with particles, chains which were in contact with one particle, and chains which were in contact with two or more particles. A statistical representation of each class is presented. The contact between chain and particle can influence macroscopic properties such as those that are elastic.     

The value of reputation

Reputation plays a central role in human societies. Empirical and theoretical work indicates that a good reputation is valuable in that it increases one''s expected payoff in the future. Here, we explore a game that couples a repeated Prisoner''s Dilemma (PD), in which participants can earn and can benefit from a good reputation, with a market in which reputation can be bought and sold. This game allows us to investigate how the trading of reputation affects cooperation in the PD, and how participants assess the value of having a good reputation. We find that depending on how the game is set up, trading can have a positive or a negative effect on the overall frequency of cooperation. Moreover, we show that the more valuable a good reputation is in the PD, the higher the price at which it is traded in the market. Our findings have important implications for the use of reputation systems in practice.