数码城市GIS日照分析模型

本文着重介绍了基于数码城市GIS的几种常用日照分析实现方法及其特点，包括实现动态的三维阴影，对不同地区，不同季节的各种复杂建筑物单点进行日照时间计算。基于数码城市GIS进行日照环境分析，在三维场景中再现一天内日照阴影的变化比二维中目照阴影分析更全面、生动、直观。     

傅里叶单元在航空发动机机匣强度振动分析中的应用

基于ANSYS内置的二维傅里叶轴对称单元,研究该单元在具有轴对称特征的航空发动机机匣静强度和振动分析中的应用,通过在傅里叶单元周向展开截面上设置轴向加强筋等措施,使二维傅里叶轴对称单元可以用于处理具有轴对称特征、但局部存在非轴对称属性(如存在轴向安装边)的航空发动机机匣应力、变形沿周向不均匀度和振动问题。研究结果表明:相对于三维实体机匣分析模型,二维傅里叶轴对称单元可以有效降低航空发动机机匣计算规模,并可以获得基于二维传统轴对称机匣分析模型无法得到的机匣变形沿周向的不均匀度和振动分析结果。     

三维影像显示技术窥探

人们为如何能获取与显示移动影像的立体特征进行了长期不懈地努力。在数字技术与网络信息技术以及虚拟现实技术的支撑下 ,人们在传统的二维平面影像显示技术基础之上开始了影像的三维显示的研究与探索。目前 ,影像三维立体的显示不但已经能够实现跨时空的传递 ,而且影像直观、立体与真实 ,更加接近了人们长久梦想的超越时空障碍、建立“准”面对面的“在场”式交流模式。因此 ,三维影像显示技术是二十一世纪的技术 ,也是人类未来交流的主流模式。     

基于SkyLine的农村土地调查服务系统

利用已实施的全国第二次土地大调查为契机,研究3DGIS技术在农村土地调查数据库信息系统上的应用,利用三维包容几乎所有丰富的空间信息资源及逼真显示现实场景的优势,突破二维GIS的局限性,实现土地资源信息从传统的二维管理模式转变为更有效直观的三维表现形式。     

摄影如何对空间进行表现对空间进行表现

表现空间是摄影的造型任务之一。摄影造型的任务就是要在照片二维的平面上,运用摄影的手段足够令人信服地表达出三维的现实世界,以及现实世界的空间、体积和表面结构(如图1)。一幅摄影作品的生命力和真实性如何体现呢?在很大程度上取决于摄影者对所熟悉的现实世界的空间、体积和表面结构等特征在摄影作品中如何采用三维的、富有表现力的方式表达出来,使观众充分相信照片中现实世界的这些特征的存在,同时,摄影作品还应当引起观众视觉上的联想,从而引导观众走向真正的生活。用摄影的手段富有表现力地表达出现实世界的空间、体积和表面结构…     

三维影像显示技术窥探

人们为如何能获取与显示移动影像的立体特征进行了长期不懈地努力。在数字技术与网络信息技术以及虚拟现实技术的支撑下，人们在传统的二维平面影像显示技术基础之上开始了影像的三维显示的研究与探索。目前，影像三维立体的显示不但已经能够实现跨时空的传递，而且影像直观、立体与真实，更加接近了人们长久梦想的超越时空障碍、建立“准”面对面的“在场”式交流模式。因此，三维影像显示技术是二十一世纪的技术，也是人类未来交流的主流模式。     

增强现实系统中的三维用户界面设计

随着科技的发展,增强现实技术应运而生,三维用户界面中的交互模式也成为新一代以人为中心的用户界面的重要模式之一。它与传统二维用户界面交互区别在于交互方式、界面隐喻以及可用性等方面的改变。本文主要探讨了如何利用手势交互技术来设计虚实交互环境中的用户界面,以提高增强现实中三维世界的用户视觉真实感和三维交互感。     

摄影如何对空间进行表现

表现空间是摄影的造型任务之一.摄影造型的任务就是要在照片二维的平面上,运用摄影的手段足够令人信服地表达出三维的现实世界,以及现实世界的空间、体积和表面结构(如图1).一幅摄影作品的生命力和真实性如何体现呢?在很大程度上取决于摄影者对所熟悉的现实世界的空间、体积和表面结构等特征在摄影作品中如何采用三维的、富有表现力的方式表达出来,使观众充分相信照片中现实世界的这些特征的存在,同时,摄影作品还应当引起观众视觉上的联想,从而引导观众走向真正的生活.用摄影的手段富有表现力地表达出现实世界的空间、体积和表面结构等三维特性,是摄影者要长期学习和研究的课题.那么怎样用摄影的手段表现空间的造型呢?     

基于小波分析的近岸海面风场反演研究

提出了利用小波变换多尺度分析合成孔径雷达(SAR)影像获取海面风向信息并结合岛礁、船舶等物体背风面形成的风阴影进行风向模糊剔除的近岸海面风场反演算法.与二维傅里叶变换谱分析方法得到的风向反演结果相比,小波分析法可充分发掘不同尺度影像中包含的风向信息,降低了对影像周期性线性纹理特征的依赖,提高了风场反演的分辨率和精度.由...     

基于三维轻模型的装配MES系统关键技术

针对现阶段产品设计已经实现三维数字化,但在航空等典型离散行业的制造现场仍以二维工程图为产品制造依据的现实,提出了基于三维轻模型的装配MES系统,将产品设计数据向制造过程延伸,并结合MBD( ModelBased Definition,基于模型的定义)技术实现基于三维轻模型的装配工艺定义,以三维轻模型为车间现场装配生产的...     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Synthesis of Alumina-Zirconia Nanocomposites by Solgel Process

Al₂O₃-ZrO₂ nanocomposites were developed starting with the solgel process. Composite alumina-zirconia nanopowders were synthesized from metallorganic precursors (Aluminium secondary butoxide and zirconium Iso propoxide) using the solgel process. The parameters affecting the synthesis—solvent, concentration of precursor, R/H ratio (i.e., dilution of water in solvent)—were varied as also the temperature and pH. BET and TEM were used to measure nanosize. Diffuse reflectance spectroscopy and also qualitative optical absorption led to identical particle size estimate. The variation of process parameters was used to study the effect and interdependence of process parameters. Artificial Neural Networks was used to rigorously analyze the process. Although this led to confirmation of interdependence of parameters, the presence of a single overwhelming solvent variable was also established. Then the optimal process was used to synthesize more nanopowder. To produce bulk nanocomposite the nanopowders were sintered by varying the temperature and time period. The sintered lithoids were probed with a vickers hardness tester to measure elastic modulus, hardness, and fracture toughness. The results showed high elastic modulus, modest hardness, and very high fracture toughness.     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.