大型数据仓库实现技术的研究

大型数据仓库是实现海量数据存储的有效途径,但在大型数据仓库的实现中存在很多问题。在分析问题的基础上,对大型数据仓库的实现问题提出了一定的解决策略,对其中的几个关键技术即数据立方体的有效计算、增量式更新维护、索引优化、故障恢复、模式设计和查询优化的代价模型及元数据的定义和管理等作了研究。     

数据仓库和数据挖掘技术在DSS中的应用研究

数据仓库和数据挖掘技术是目前信息技术研究的热点问题之一。介绍了数据仓库的特点、体系结构、联机分析处理及数据挖掘技术,讨论了如何在Microsoft SQL Server2000中将数据仓库和数据挖掘技术结合起来开发决策支持系统。     

基于数据仓库技术的银行决策支持系统设计和实现

该文提出了一种基于数据仓库、在线分析处理及数据挖掘的银行决策支持系统(BANK-DSS)解决方案,较好地解决了传统四库结构的决策支持系统中的协作问题。在此思想的基础上,通过分析研究,讨论了数据仓库的基本技术,归纳并提出了银行数据仓库的基本体系结构,以客户关系管理、风险管理、盈利管理和负债管理为应用主题,确立了相应的数据表及技术指标。设计了一种集成化的决策支持系统基本框架,以数据仓库为基础,支持联机分析处理,并将数据挖掘应用于数据库中的知识发现。     

Design and implementation of a file system with on‐the‐fly data compression for GNU/Linux

Data compression techniques have long been assisting in making effective use of disk, network and other resources. Most compression utilities require explicit user action for compressing and decompressing of file data. However, there are some systems in which compression and decompression of file data is done transparently by the operating system. A compressed file requires fewer sectors for storage on the disk. Hence, incorporating data compression techniques into a file system gives the advantage of a larger effective disk space. At the same time, the additional time needed for compression and decompression of file data gets compensated for to a large extent by the time gained because of fewer disk accesses. In this paper we describe the design and implementation of a file system for the Linux kernel, with the feature of on‐the‐fly data compression and decompression in a fashion that is transparent to the user. We also present some experimental results which show that the performance of our file system is comparable to that of Ext2fs, the native file system for Linux. Copyright © 1999 John Wiley & Sons, Ltd.     

Dual‐rate sampled‐data stabilization for active suspension system of electric vehicle

In this paper, we consider the dual‐rate sampled‐data state‐feedback control problem for an active suspension system of an electric vehicle. In the active suspension system, there exist 2 accelerometers to measure the heave acceleration of the sprung mass and the vertical acceleration of the unsprung mass, respectively. When the 2 accelerations are measured by sampled data under different sampling periods, the difficulty arising from the dual‐rate sampled data makes the active suspension stabilization problem challenging but interesting. In this paper, a linear hybrid stabilizer is proposed, which is implemented using dual‐rate sampled‐data state feedback. In order to deal with the more difficult stabilization problem under different triggering time instants, a coordinate transformation is proposed. A useful technical theorem is proposed in the stability analysis to show that the proposed hybrid controller can guarantee the states of the active suspension system being asymptotically stabilized or at least bounded to arbitrarily small domains. The experiment result is similar to the simulation result and indicates that the proposed active suspension controlling system is effective.     

超大型压缩数据仓库上的CUBE算法

数据压缩是提高多维数据仓库性能的重要途径,联机分析处理是数据仓库上的主要应用,Cube操作是联机分析处理中最常用的操作之一.压缩多维数据仓库上的Cube算法的研究是数据库界面临的具有挑战性的重要任务.近年来,人们在Cube算法方面开展了大量工作,但却很少涉及多维数据仓库和压缩多维数据仓库.到目前为止,只有一篇论文提出了一种压缩多维数据仓库上的Cube算法.在深入研究压缩数据仓库上的Cube算法的基础上,提出了产生优化Cube计算计划的启发式算法和3个压缩多维数据仓库上的Cube算法.所提出的Cube算法直     

基于数据仓库技术的教育评价决策系统的实现

针对高校教务管理系统中存在的不足，将数据仓库技术引入高校教育评价决策支持系统。设计了基于数据仓库和0LAP技术的教育评价决策支持系统的体系结构，描述了各逻辑服务模型的具体功能。文章重点介绍了运用Microsoft SQL Server2000提供的数据透视表服务，由ADO MD对象模型访问数据仓库服务器，最终实现了客户端的数据多维分析与查询．基于数据仓库的教育评价决策系统克服了传统决策支持系统的弊端，增强了高校教务管理功能，对于提高教育质量、促进教育发展具有现实意义。     

基于数据仓库的房地产数据分析系统

针对房地产信息系统积累的大量房产数据,研究并实现基于数据仓库及OLAP技术的房地产智能数据分析系统.首先建立了分离的数据仓库,并对数据仓库进行多维建模和多维分析;然后对多维数据模型进行了切片、切块,旋转、上钻和下钻等多维分析,从多角度进行房产数据分析,并计算房产指数;最后利用前端开发工具开发了可视化的多维分析和数据展示平台.实践表明,基于数据仓库的房产数据分析系统可以为房地产管理层和决策层提供高效的决策支持.     

实时主动数据仓库中多维数据实视图的选择

通过基于主动决策引擎日志的数据挖掘来找到分析规则的CUBE使用模式,从而为多维数据实视图选择算法提供重要依据;在此基础上设计了3A概率模型,并给出考虑CUBE受访概率分布的视图选择贪婪算法PGreedy(probability greedy),以及结合视图挽留原则的视图动态调整算法.实验结果表明,在实时主动数据仓库环境下,PGreedy算法比BPUS(benefit per unit space)算法具有更好的性能.     

数据仓库中维的建模和查询

维是数据仓库的重要组成部分，也是OLAP的主要查询对象，但标准的星形／雪花模型对实际应用中维的建模存在明显缺陷，而且SQL语言对维实体、维层次结构不能提供直接、有效的支持，使得OLAP查询的表达较为繁琐、冗长。为此，提出了一个基于关系数据库的SQL（D）数据模型，它给出了层次链、层次树、维的正式定义，支持不平衡、异构的维层次结构；并对SQL作了相应的扩充，支持维的定义、维层次比较、维的引用和维聚集层次的指定，使得原先冗长、复杂的OLAP查询表达式变得简洁、易于理解。最后对扩充的语义给出实现算法。     

A relational–XML data warehouse for data aggregation with SQL and XQuery

Integrating information from multiple data sources is becoming increasingly important for enterprises that partner with other companies for e‐commerce. However, companies have their internal business applications deployed on diverse platforms and no standard solution for integrating information from these sources exists. To support business intelligence query activities, it is useful to build a data warehouse on top of middleware that aggregates the data obtained from various heterogeneous database systems. Online analytical processing (OLAP) can then be used to provide fast access to materialized views from the data warehouse. Since extensible markup language (XML) documents are a common data representation standard on the Internet and relational tables are commonly used for production data, OLAP must handle both relational and XML data. SQL and XQuery can be used to process the materialized relational and XML data cubes created from the aggregated data. This paper shows how to handle the two kinds of data cubes from a relational–XML data warehouse using extract, transformation and loading. Copyright © 2008 John Wiley & Sons, Ltd.     

Fully‐integrated active matrix programmable UV and blue micro‐LED display system‐on‐panel (SoP)

High pixel per inch and high‐resolution micro‐LED displays are attracting more and more attentions. The increasing pixel number requires a large amount of bonding pads and brings huge difficulties to micro‐LED system design and lowers power efficiency as well. It is urgent to integrate row and column driving circuits onto the micro‐LED panel. Here, we report a fully integrated active matrix programmable micro‐LED system on panel (SoP) with ultraviolet and blue emission wavelengths. The micro‐LED SoP has a resolution of 60 × 60 and pixel pitch of 70 μm. The micro‐LED SoP was achieved by integrating micro‐LED arrays with silicon‐based p‐channel metal‐oxide semiconductor driving panel using fine‐toned flip‐chip bonding technology. With fully integrated scan and data circuits, the number of bonding pads was greatly reduced from 136 to 28, and large amount of metal interconnection lines were saved. The micro‐LED SoP panel was mounted on a periphery driving board, and representative characters were displayed successfully.     

On‐demand data co‐allocation with user‐level cache for grids

Conventional remote data access middlewares usually provide client applications with either a pre‐staging scheme or an on‐demand access scheme to fetch data. The pre‐staging scheme uses parallel downloads to fetch a completed input file from multiple data sources, even when only a tiny file fragment is required. Such a transfer scheme consumes unnecessary data transmission time and storage space. In contrast, the on‐demand scheme downloads only the required data blocks from a single data source and does not fully utilize the downstream bandwidth of the computing nodes. This paper presents a middleware called ‘Spigot’ that facilitates legacy (grid‐unaware) applications to transparently access remote data by using native I/O function calls. Spigot uses the on‐demand concept to avoid unnecessary data transfer and adopts a co‐allocation download algorithm to improve the data transfer performance. Moreover, it uses the pre‐fetching strategy to reduce the data waiting time by overlapping data acquisition and data processing. It also provides the client application with its own user‐level cache, which is advantageous since a larger cache space is available in comparison with the kernel‐level cache. Further, it is easy to maintain data consistency between Spigot nodes. The experimental results indicate that Spigot achieves superior performance in reducing the data waiting time than the pre‐staging and the on‐demand access schemes. Copyright © 2010 John Wiley & Sons, Ltd.     

A small‐area and low‐power data driver IC using two‐stage DAC with a capacitor array for active matrix flat‐panel displays

A small‐area and low‐power data driver integrated circuit (IC) using a two‐stage digital‐to‐analog converter (DAC) with a capacitor array is proposed for active matrix flat‐panel displays. The proposed data driver IC employs a capacitor array in the two‐stage DAC so as to reduce the DAC area and eliminate the need for a resistor string, which has high‐power consumption. To verify the proposed two‐stage DAC, a 20‐channel data driver IC with the proposed 10‐bit two‐stage DAC was fabricated using a 0.18‐μm complementary metal–oxide–semiconductor process with 1.8 and 6 V complementary metal–oxide–semiconductor devices. The proposed 10‐bit two‐stage DAC occupies only 43.8% of the area of a conventional 10‐bit two‐stage DAC. The measurement results show that the differential nonlinearity and integral nonlinearity are +0.58/?0.52 least significant bit and +0.62/?0.59 least significant bit, respectively. The measured interchannel deviation of the voltage outputs is 8.8 mV, and the measured power consumption of the 20‐channel data driver IC is reduced to 7.1 mW, which is less than half of the power consumed by the conventional one.     

基于人工免疫检测的商业智能系统*

设计商业智能系统,分别构建ETL模块、数据仓库和OLAP系统。对于Cube中经常出现的异常数据问题,提出使用人工免疫系统进行检测,将Cube查询的KPI历史数据进行二进制编码作为自我集合,并用阴性选择算法产生检测器。设计基于人工免疫检测的新商业智能系统,测试表明,改进的系统可以有效地检测异常数据的存在,从而保障了最终用户端使用数据的准确性和整个商业智能系统的可靠性。     

Low‐temperature poly‐Si TFT data drivers for an SVGA a‐Si TFT‐LCD panel

Low‐temperature poly‐Si TFT data drivers for an SVGA a‐Si TFT‐LCD panel have been developed. The data drivers include shift registers, sample‐and‐hold circuits, and operational amplifiers, and drive LCD panels using a line‐at‐a‐time addressing method. To reduce the power consumption of the shift register, a dot‐clock control circuit has been developed. Using this circuit, the power consumption of the shift register has been reduced to 36% of that of conventional circuits. To cancel the offset voltage generated by the operational amplifier, an offset cancellation circuit for low‐temperature poly‐Si TFTs has been developed. This circuit is also able to avoid any unstable operation of the operational amplifier. Using this circuit, the offset voltage has been reduced to one‐third of the value without using the offset cancellation circuit. These data drivers have been connected to an LCD panel and have realized an SVGA display on a 12.1‐in. a‐Si TFT‐LCD panel.     

A novel low‐power‐consumption all‐digital system‐on‐glass display with serial interface

Abstract— A new conceptual ultra‐compact LCD panel, which features a simple interface and lower‐power consumption by using low‐temperature polysilicon thin‐film transistor (LTPS‐TFT) technology has been developed. This panel is capable of switching operation modes based on an input command, and all the data are directly communicated with the circuit inside the panel through a Serial Peripheral Interface (SPI) protocol. The integration of the serial‐data‐receiver function on glass substrate has enabled the achievement of a significant reduction in the number of interface pins. Moreover, a low power consumption of 15 μW for a 2.26‐in. reflective LCD panel in combination with the technique of integrating a memory circuit in each pixel has been achieved.     

MOSFET‐C‐based grounded active inductors with electronically tunable properties

In this study, two new grounded metal oxide semiconductor field effect transistor (MOSFET)‐C active inductors (AIs) are proposed. The proposed AIs contain only eight MOS transistors and a single grounded capacitor that is attractive for integrated circuit fabrication. Inductance values of them can be electronically tuned by a single control voltage. They do not include any current sources. Therefore, the designs of the proposed AIs are simple and useful. They do not suffer from body effects. Hence, they can be designed with low power supply voltages. Simulation results by using the Cadence analog environment program with 180 nm Taiwan Semiconductor Manufacturing Company (TSMC) nm technology parameters are carried out to indicate the performance of them. Layouts of both proposed AIs occupy the same area of about 78 μm × 78 μm. Postlayout simulation results are given to confirm the validity of the theoretical analysis.     

A database approach for information communication in a peer‐to‐peer collaborative CAD environment

Timely and efficient information communication is a key factor in ensuring successful collaboration in engineering collaborative design. This work proposes a database approach to support information communication between distributed and autonomous CAD systems. It provides the designer with an easy and flexible way, a project‐based propagation meta‐table, to specify what parts of a CAD information model should be communicated to other collaborating designers. A CAD peer manager, containing a peer database that stores information to be exchanged with the other collaborators, wraps each participating CAD system. The peer manager identifies changes made to the CAD model by using stored procedures and active rules in the peer database that are automatically generated based on the propagation meta‐table. The identified updates are propagated in a timely manner to other peers via inter‐database message passing, thereby minimizing the volume of necessary information to be exchanged. Furthermore, remote peer designers can flexibly incorporate, filter, or delete received updates by using a propagation control interface, which is also used to issue user's commands to download the data from the CAD system to the peer database and lookup the received messages in the peer database. The approach is applicable on any CAD system having a CORBA interface and can also be applied to other kinds of object‐oriented interfaces. Copyright © 2007 John Wiley & Sons, Ltd.     

On‐the‐Fly and Incremental Technique for Fault Diagnosis of Discrete Event Systems Modeled by Labeled Petri Nets

In this paper, we develop an on‐the‐fly and incremental technique for fault diagnosis of discrete event systems modeled by labeled Petri nets, in order to tackle the combinatorial explosion problem. K‐diagnosability, diagnosability, K_min (the minimum K ensuring diagnosability) and on‐line diagnosis are solved on the basis of the on‐the‐fly and incremental building of two structures, called respectively fault marking graph and fault marking set graph, in parallel. We build on existing results, namely those establishing necessary and sufficient conditions for diagnosability, but we bring mechanisms to make the checking of such conditions potentially more efficient. We show that, in general, analyzing or even building the whole reachability graph is unnecessary to analyze diagnosability and build an on‐line diagnoser. Our technique was implemented in a prototype tool called OF‐PENDA, and a railway level crossing benchmark is used to make a comparative discussion pertaining to efficiency in terms of time and memory relative to some existing approaches.