理想材料零件实体模型自动添加支撑技术研究

在一些RP工艺中，给各种形状的零件添加支撑对于完成零件的制造和保证零件的精度非常重要，但目前尚无很好的自动添加支撑算法能够应用于一般的情况．为此提出两种自动添加支撑算法：曲线追踪法和标志位追踪法．前者主要是在切片前基于追踪得到的采样点利用蒙面法重构支撑面片；而后者则是在切片后通过多边形的布尔运算逐层计算各切层端面的实际轮廓和综合轮廓．这两种算法形成了一种新的自动添加支撑方案．实例证明了这种方案的有效性和便利性．     

基于Pro／ENGINEER、RP和RT技术的模具设计制造

以农用滴灌滴头的模具设计为例,介绍了使用Pro/ENGINEER、RP和RT技术设计制造模具的工艺过程。Pro/ENGINEER的应用能实现屏幕的三维显示,减少产品研制过程的迭代,加快产品的开发;RP技术的应用可以制造出实物,避免造型与实际要求的不一致性,加速模具设计进程并迅速确定模具制造工艺;RT技术能进一步提高RP技术的效益,快速制造出模具。在应用各种高新技术进行模具设计制造的同时,针对设计制造过程中的难点和问题提出了有效的解决方法。     

电偏转抛射式快速成型工艺的仿真

基于电偏转抛射式快速成型(RP)工艺方法是通过电场控制带电颗粒的运动轨迹实现分层截面的成型，作者开发了电偏转的抛射式RP工艺的仿真系统．该仿真系统读入CLI格式的层面数据后，根据分层截面轮廓数据生成工艺规化和扫描路径，控制带电的颗粒进行扫描，并在计算机屏幕上实时模拟显示扫描轨迹及原型件的三维实体成型过程．为电偏转抛射式快速成型工艺的试验研究提供一定的理论依据．     

基于VB6.0的实时波浪功率谱分析软件

介绍一种基于VB6.0设计实现快速付里叶变换(FFT)模块的方法,并在此基础上设计编写了实时海浪功率谱分析软件。经过实验室和海上现场实测数据验证,该软件的运算和处理结果准确可靠,实际应用取得较好的效果。设计的FFT运算模块具有一定的通用性,可用于其它随机信号频谱分析。     

AIS盲分离接收机的FPGA实现及系统验证

针对卫星平台接收多个AIS小区内船舶发射的同频信号时存在互相冲突无法解调的问题,基于FPGA设计了一个多天线盲分离接收机,在FPGA上设计了实时的盲分离系统和AIS信号处理模块来对多小区混合信号进行分离和解调.模块包括AIS信号处理模块和高精度的数据白化模块,以及基于Fast ICA算法的实时权值矩阵迭代求解模块.采用CORDIC IP核与浮点运算IP核提高白化精度,保证算法分离效果.实际系统测试表明:设计的接收机可以成功分离并正确解调由两路AIS发射机同时发射的AIS信号,通过对比分离信号和发射信号的鉴频波形,验证了分离的正确性.所设计的系统也可应用于雷达、声纳等可能存在同频干扰的实时信号处理系统.     

RP技术在硅胶模快速成型中的应用

本文介绍了RP技术原理，重点阐述了利用RP技术制造导流罩硅胶模的过程，强调了制造过程应注意的一些问题。实现了导流罩等壳类零件快速制模和复制，可经济快捷地小批量制作塑料产品，满足使用要求。     

数控机床热误差实时补偿应用

将由机床热变形引起的、决定工件加工误差的工件与刀具间相对热位移通过机床数控系统的外部机床坐标系偏置来实现实时补偿，并研制开发了高精度、低成本、满足实际加工要求的热误差实时补偿控制器，经数家企业实际生产使用，数控机床的加工精度大幅度提高，从而验证了本方法的正确性和本实时补偿控制器的有效性。     

STL切片数据的NURBS曲线拟合算法

在快速成形加工过程中，由于对STL文件切片所得数据是由极不均匀的细微离散线段序列组成，为提高制件加工速度和精度，必须对切片数据进行重新拟合处理，为简化后续插补处理，不适宜采用抛物线、双曲线、B样条等标准圆锥曲线及不规则参数等多种类型组合曲线拟合，基于此，提出了一种合适于STL文件切片数据的二次NURBS曲线拟合算法，以便对于标准曲线和自由曲线提供统一的表达式。     

STEP-NC仿真系统研究

为满足STEP-NC数控系统研究的需要,提出基于STEP-NC仿真系统的方案.该系统采用模块化设计,译码器由解析模块、建模模块和路径规划模块构成,根据STEPNC程序特点完成程序解析、加工类库模型建立和刀具路径规划功能,其他模块完成实时加工仿真功能.作为独立模块的译码器,其数据接口用于仿真系统与实际数控系统进行数据交换,其路径信息接口设计为直线和圆弧两种单元类型,作为仿真和加工的计算依据.仿真和加工实验证明该仿真系统运行正确,说明基于STEP-NC仿真系统及译码器可以作为独立的功能模块嵌入数控系统.     

一种基于VHDL的线性卷积快速算法

传统的线性卷积方法在处理实际工程中经常遇到输入序列具有较长持续时间的情况时，无法达到信号“实时”处理的要求，一般采用分段卷积的思想完成设计。文章设计了一种基于VHDL的快速线性卷积的模块，该模块以XILINX公司的FPGA芯片VIRTEX2V3000作为控制和处理核心，经检验该方法正确且能很好地满足对信号进行实时处理的要求。     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with     

Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to     

《Chinese Science Bulletin》SUBJECT INDEX TO VOLUME 59(2014)

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An on-line scaling method for improving scalability of a database cluster

The explosive growth of the Internet and database applications has driven database to be more scalable and available, and able to support on-line scaling without interrupting service. To support more client's queries without downtime and degrading the response time, more nodes have to be scaled up while the database is running. This paper presents the overview of scalable and available database that satisfies the above characteristics. And we propose a novel on-line scaling method. Our method improves the existing on-line scaling method for fast response time and higher throughputs. Our proposed method reduces unnecessary network use, i.e. , we decrease the number of data copy by reusing the backup data. Also, our on-line scaling operation can be processed parallel by selecting adequate nodes as new node. Our performance study shows that our method results in significant reduction in data copy time.     

An improved R-tree based on childnode''s probability

R-Tree is a good structure for spatial searching. But in this indexing structure,either the sequence of nodes in the same level or sequence of traveling these nodes when queries are made is random. Since the possibility that the object appears in different MBR which have the same parents node is different, if we make the subnode who has the most possibility be traveled first, the time cost will be decreased in most of the cases. In some case, the possibility of a point belong to a rectangle will shows direct proportion with the size of the rectangle. But this conclusion is based on an assumption that the objects are symmetrically distributing in the area and this assumption is not always coming into existence. Now we found a more direct parameter to scale the possibility and made a little change on the structure of R-tree, to increase the possibility of founding the satisfying answer in the front sub trees. We names this structure probability based arranged R-tree (PBAR-tree).     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Integrating GIS Web services based on mediating architecture

The geographic information service is enabled by the advancements in general Web service technology and the focused efforts of the OGC in defining XML-based Web GIS service. Based on these models, this paper addresses the issue of services chaining,the process of combining or pipelining results from several interoperable GIS Web Services to create a customized solution. This paper presents a mediated chaining architecture in which a specific service takes responsibility for performing the process that describes a service chain. We designed the Spatial Information Process Language (SIPL) for dynamic modeling and describing the service chain, also a prototype of the Spatial Information Process Execution Engine (SIPEE) is implemented for executing processes written in SIPL. Discussion of measures to improve the functionality and performance of such system will be included.