通用数据访问技术的发展及其应用

本文介绍了通用数据访问技术的发展概况,着重剖析了一致数据访问技术ADO/OLE DB以及最新数据访问技术ADO.Net,并给出了通用数据访问技术的应用策略.     

基于热点数据块的动态副本调整策略

副本管理策略对于分布式存储系统的可用性、可靠性和系统整体性能有至关重要的作用。本文针对基于文件的动态副本调整策略的不足,提出了一种基于热点数据块的动态副本调整策略。根据时间局部性原理和数据访问规律,通过对历史访问周期和当前周期赋予不同的权重,数据块下一周期的预测进行访问频率计算,接下来基于计算出的预测访问频率对数据块进行热点判定。结合HDFS中数据访问规律近似二八定律的特点和热点数据块的判定结果,来确定数据块的调整阈值。最后,分3个步骤对基于热点数据块的动态副本调整策略进行性详细设计。实验结果表明,本文提出的基于热点数据块的动态副本调整策略在数据访问效率和集群存储资源利用率两方面有了明显提升。     

多源空间数据的共享与集成模式研究

在研究现有多格式空间数据共享与集成模式的基础上,借鉴通用数据访问(UniversalDataAccess,UDA)技术为传统多源数据提供通用数据访问的思路,作者提出了基于通用空间数据引擎(UniversalSpatialDataEngine,USDE)的空间数据共享与集成模式。通用空间数据引擎由数据引擎管理器及相应的一系列数据引擎构成,其中数据引擎管理器负责数据引擎的智能调用,并为客户GIS软件提供统一的数据访问接口;各数据引擎负责对具体数据访问接口的实现。利用COM技术,作者设计出了基于目前几种流行的GIS数据格式的USDE,并成功地实现了对几种不同格式空间数据的集成应用。     

面向多兴趣区域图像处理应用的高效无冲突并行访问存储模型

针对不规则数据访问模式图像处理应用提出了一种通用的高效无冲突并行访问存储模型.在主存储器与处理器之间构建了一种多体存储结构,并将大部分的不规则数据访问模式归类为对图像中多个局部矩形兴趣区域内的任意位置固定大小矩形数据块的无冲突并行访问.为了提高访问效率,只将兴趣区域内的数据缓存在多体存储器中,且不同兴趣区域的重叠数据可以重用.多体存储器的寻址机制是基于提出的地址映射表结构进行动态寻址,而不是采用传统的固定寻址函数,既保证了对任意数据读写操作的编址一致性,又提高了数据重用性.每处理一个新兴趣区域就对地址映射表内容进行一次更新,提出的双表结构与数据块动态调度机制保证了更新过程与计算过程的并行执行.基于提出的存储模型构建了硬件体系结构,并在FPGA上实现,测试结果表明,与直接访问主存储器相比在访存速度上提高了几倍到上百倍.     

可定制的通用数据访问模型的设计与实现

通过对元数据库结构定义和通用数据访问的设计,给出了一个可定制的通用数据访问模型的设计及实现方法,使能通过定制完成数据访问和展示,降低数据库应用系统的开发难度。最后给出了模型在远程教学系统和器材管理的应用。     

基于异构集成的元数据及其多表动态查询算法

基于企业内多个分布异构关系数据库的集成需求，设计了一个向上支持集成访问界面，向下表述数据库网络位置、数据模式、数据内容的元数据字典模式。给出了面向集成环境和各异构数据库的通用查询请求表示。基于元数据字典，提出了一种因访问需求变化而引起相关数据库关系表动态变化的动态查询语句构造算法，并对算法进行了论证。     

一种基于纠错码的叛逆者追踪模型

当一些共谋者试图构造一个盗版的解码器以获取对数据内容非法访问的时候，叛逆者追踪模型可以用来发现至少其中的一个叛逆者。Chor和Fiat提出了一种将数据划分为若干块并且每一块用一些不同密钥加密的叛逆者追踪模型。文中研究相同的问题，给出了一种基于纠错码并可防止最多k个用户共谋的追踪模型。基于纠错码的叛逆者追踪模型是通过纠错码来构造的。它是一种公开的、确定的并且有很好性能的模型，此模型只需将数据内容划分为8klogN块，每个数据块需要2k个密钥。     

一种基于纠错码的叛逆者追踪模型

当一些共谋者试图构造一个盗版的解码器以获取对数据内容非法访问的时候,叛逆者追踪模型可以用来发现至少其中的一个叛逆者。Chor和Fiat提出了一种将数据划分为若干块并且每一块用一些不同密钥加密的叛逆者追踪模型。文中研究相同的问题,给出了一种基于纠错码并可防止最多k个用户共谋的追踪模型。基于纠错码的叛逆者追踪模型是通过纠错码来构造的。它是一种公开的、确定的并且有很好性能的模型,此模型只需将数据内容划分为8klogN块,每个数据块需要2k个密钥。     

文件Cache自适应策略研究

Linux系统在被不同大小的数据块访问时,系统读写性能有差异。在少数特定访问数据块大小的应用中,Linux系统读写性能较差。文件Cache算法的性能是导致该问题的原因之一。在分析访问数据块大小对文件Cache算法性能的影响的基础上,提出了一种文件Cache自适应策略。该策略考虑了预取算法对于页面置换算法的影响,增强了页面置换算法对访问数据块大小变化的适应性,达到了提高Linux系统读写性能的目标。Linux系统读写性能测试实验表明,该策略可以使Linux系统在被不同大小的数据块访问时保持稳定且更优的读写性能。     

如何自动更新框上的版本信息

Windows SDK中提供访问包含在文件资源中的版本信息的接口。使用GetFileVersionlnfo函数可获取包含版本信息的整个数据块。由于数据块长度是未知的，之前需要调用GetFileVersionInfoSize函数确定数据块的长度。得到数据块后，使用VerQueryValue函数定位版本信息。版本信息有若干项，VerQueryValue定位数据需要指定一个路径，这有点类似文件系统或注册表的访问。     

The route to a defect tolerant LUT through artificial evolution

Evolutionary techniques may be applied to search for specific structures or functions, as specified in the fitness function. This paper addresses the challenge of finding an appropriate fitness function when searching for generic rather than specific structures which, when combined wiacteristic of defect tolerance on the circuit. Production defects for integrated circuits are expected to increase considerably. To avoid a corresponding drop in yield, improved defect tolerance solutions are needed. In the case of Field Programmable Gate Arrays (FPGAs), the pre-designed gate array provides a bridge between production and the application designers. Thus, introduction of defect tolerant techniques to the FPGA itself could provide a defect free gate array to the application designer, despite production defects. The search for defect tolerance presented herein is directed at finding defect tolerant structures for an important building block of FPGAs: Look-Up Tables (LUTs). Two key approaches are presented: (1) applying evolved generic building blocks to a traditional LUT design and (2) evolving the LUT design directly. The results highlight the fact that evolved generic defect tolerant structures can contribute to highly reliable circuit designs at the expense of area usage. Further, they show that applying such a technique, rather than direct evolution, has benefits with respect to evolvability of larger circuits, again at the expense of area usage.     

综合商务大厦智能信息网络系统设计

随着科技信息技术的飞速发展,人们对办公和商务所处的环境提出了更高的要求。传统的商务活动在与互联网结合后,网络信息技术为商务活动在空间与时间上提供了极大的便利。信息网络系统的综合布线是楼宇智能化系统集成的主要业务,是智能商务大厦的一个重要的组成部分。根据榆林市学X大厦设施要求,提出了学X大厦的办公自动化目标：摆脱时空限制。介绍了主要的工程概况、综合布线系统设计以及系统配置等。     

A hybrid topological–stochastic partitioning method for scaling QoS routing algorithms

This paper presents a new partitioning strategy with the objective of increasing scalability by reducing computational effort of routing in networks. The original network is partitioned into blocks (subnetworks) so that there is a bi-directional link between any two blocks. When there is a connection request between a pair of nodes, if the nodes are in the same block, we only use the small single block to derive routings. Otherwise we combine the two blocks where the two nodes locate and in this way the whole network will never be used. The strategy is generic in that it can be used in any underlying routing algorithms in the network layer and can be applied to any networks with fixed topology such as fixed wired sub-networks of the Internet. The performance of this strategy has been investigated by building a simulator in Java and a comparison with existing stochastic partitioning techniques is shown to give superior performance in terms of trade-off in blocking probability (the probability of failure to find a path between source and destination satisfying QoS constraints) and reduction of computational effort.     

Identity-based universal designated multi-verifiers signature schemes

An identity-based (ID-based) universal designated verifier signature (ID-UDVS) scheme allows a signature holder to designate a specific verifier of the signature by using a simplified public identity such as e-mail address. In the paper, we present an efficient identity-based universal designated multi-verifiers signature (ID-UDMVS) scheme by extending a single verifier to a set of multi-verifiers for verification of a signature. To achieve our goal, we construct an ID-based signature scheme providing batch verification and then, using this scheme as a building block, we firstly propose an ID-UDMVS scheme with constant signature size. Interestingly our construction method can be used as a generic method transforming an ID-UDVS scheme, which is defined in a bilinear version of the so-called ∑ protocol, to an ID-UDMVS scheme.     

A modular neural network for super-resolution of human faces

This paper presents the original and versatile architecture of a modular neural network and its application to super-resolution. Each module is a small multilayer perceptron, trained with the Levenberg-Marquardt method, and is used as a generic building block. By connecting the modules together to establish a composition of their individual mappings, we elaborate a lattice of modules that implements full connectivity between the pixels of the low-resolution input image and those of the higher-resolution output image. After the network is trained with patterns made up of low and high-resolution images of objects or scenes of the same kind, it will be able to enhance dramatically the resolution of a similar object’s representation. The modular nature of the architecture allows the training phase to be readily parallelized on a network of PCs. Finally, it is shown that the network performs global-scale reconstruction of human faces from very low resolution input images.     

A programmable spike-timing based circuit block for reconfigurable neuromorphic computing

A generic programmable spike-timing based circuit which forms the building block of a reconfigurable neuromorphic array is implemented in analog VLSI. An array of programmable spike time event coded circuit blocks is configured to implement functional circuit blocks of a spike time based neuromorphic model. A reconfigurable neuromorphic array chip with 10 event blocks is fabricated using Austria Microsystems m CMOS technology to demonstrate the functionality of the circuits in silicon.     

A golden-block-based self-refining scheme for repetitive patterned wafer inspections

Abstract. This paper presents a novel technique for detecting possible defects in two-dimensional wafer images with repetitive patterns using prior knowledge. The technique has a learning ability that can create a golden-block database from the wafer image itself, then modify and refine its content when used in further inspections. The extracted building block is stored as a golden block for the detected pattern. When new wafer images with the same periodical pattern arrive, we do not have to recalculate their periods and building blocks. A new building block can be derived directly from the existing golden block after eliminating alignment differences. If the newly derived building block has better quality than the stored golden block, then the golden block is replaced with the new building block. With the proposed algorithm, our implementation shows that a significant amount of processing time is saved. Also, the storage overhead of golden templates is reduced significantly by storing golden blocks only. Received: 21 February 2001 / Accepted: 21 April 2002 Correspondence to: S.-U. Guan     

The DFX shell: A generic framework for developing design for X tools

The Design for X (DFX) shell is a generic framework which can be easily extended or tailored to develop a variety of DFX tools quickly with consistent quality. A number of formal but pragmatic constructs are provided. Bills of materials are used to describe and analyse the overall product structure and product characteristics. Flow process charts are used to describe and analyse the overall process structure and process characteristics in relation to individual product elements. Standard operation process charts are modified to describe and analyse the overall process structure in relation to the product structure. Appropriate performance measures are used to evaluate the interactions between the elements of products, processes and resources. This paper discusses a systematic DFX development procedure. The DFX development procedure consists of seven steps, and each step focuses on a major building block of the DFX shell.     

EarlyData knowledge base for material decisions in building design

To make use of the great opportunities for emission reduction in early building design, future emissions need to be calculated when only geometric, but no detailed material information about a building is available. Currently, early design phase life cycle assessments (LCAs) are heavily reliant on assumptions of specific material choices, leading to single point emission values which suggest a precision not representative for an early design stage. By adding knowledge about possible locations and functions of materials within a building to life cycle inventory (LCI) data, the EarlyData knowledge base makes LCA data sets accessible and more transparent. Additionally, “generic building parts” are defined, which describe building parts independently of precise material choices as a combination of layers with specific functions. During evaluation, enriched LCI data and generic building parts enable assessment of a vast number of possible material combinations at once. Thus, instead of single value results for a particular material combination, ranges of results are displayed revealing the building parts with the greatest emission reduction potential. The application of the EarlyData tool is illustrated on a use case comparing a wood building and a concrete building. The database is developed with extensibility in mind, to include other criteria, such as (life cycle) costs.     

Structuring urban data

Geometric city modeling is an open problem without standard solutions. Within this problem, there appear several sub-problems that must be faced, like the accurate modeling of streets, buildings and other architectonic structures. One important source of geographical information is (measured) cadastral urban data. However, this information is not always well structured, and sometimes it is even simply corrupted GIS data. In this paper we present a robust and generic solution for the generation of block and building layouts based on a repairing process applied when this data is not correct. Our input data is a top projection map of a city which usually has been created by a mixture of photogrammetric restitution and, in a second stage, hand-drawn using any GIS application. Moreover, these maps are under continuous modifications, like in the case of public administrations. This process sometimes results in the introduction of mistakes and anomalies, which are hard to correct without the appropriate tools. Our solution is based on a novel semi-automatic 2D restructuring algorithm, which uniformly corrects errors and ambiguities that are commonly present in corrupted cadastral data. This problem is complex because it is necessary to identify not just simple elements from the input file, but also their connectivity and structure in the real world. The output of our algorithm is the urban data restructured into a hierarchy of blocks and buildings, from which we can get a realistic 3D model by extruding each building using the floor number for each building within the cadastral data.