面向对象数据库的关键技术研究

面向对象数据库作为第三代数据库,具有前两代数据库无法比拟的优点,满足复杂数据结构和海量存储需要,是新型数据库如多媒体数据库﹑空间数据库﹑演绎数据库﹑工程数据库的实现基础。本文作为综述第1部分,通过对比传统数据库不足来说明面向对象数据库优点,介绍面向对象数据库3种关键技术:数据库转换﹑模式演进﹑视图实现,阐述其原理并评论其优缺点。     

基于依赖关系的大规模主题数据库的分解模式

本文对主题数据库之间的依赖关系进行了定义和说明,并细分其为实体依赖和操作依赖.在此基础上,对主题数据库之间的依赖关系进行了度量,提出了主题数据库之间的相对依赖度和相对被依赖度,并以此确定主题数据库的规模大小.最后给出了分解主题数据库算法的描述.通过这个算法可以把大规模的主题数据库科学地分解成若干个子主题数据库,降低子主题数据库之间的依赖度,同时又保证了主题数据库内部的联系是紧密的,大大提高了检索数据库的效率,并且有利于对主题数据库的管理和维护.     

对基于旁路技术的数据库审计的思考

关键业务系统在数据库平台运行后,数据库中储存着重要和敏感的信息,而且关键业务系统必须不间断的运行,对数据库审计设计,应采用旁路模式进行,数据库审计要全方位审计数据库的情况,来实现数据库的保密性、完整性和有效性的工作。     

基于ArcGIS的林业GIS空间数据库建设的研究

为了实现数字林业GIS空间数据库的建设,通过设计林业Geodatabase数据模型,收集和整理数据,利用ArcSDE和关系数据库管理系统建立了图形数据库和属性数据库,用关键字将两者连接成统一的林业GIS空间数据库.实现林业地理信息系统空间数据库中图形数据库和属性数据库的统一存储.     

数据库销毁系统的设计与实现

设计并实现了一种数据库销毁系统,该系统设计了一种数据库覆写方法,并基于该方法实现了数据库本地自毁功能和远程销毁功能.当数据库服务器处于"失控"状态时,为了防止数据库为他人所用,用户可以使用该系统销毁数据库.利用数据库自毁功能,用户可以随时对数据库进行销毁,利用数据库远程销毁功能,用户可以随地对数据库进行销毁.该系统销毁后的数据信息具有不可恢复性,是一种安全可靠的数据库销毁系统.     

基于面向对象的数据库设计研究

随着科学技术的飞速发展,数据库技术如今已经步入第三代,即面向对象数据库,与前两代数据库相比,面向对象数据库有着非常明显的优势,虽然其并没有非常高深的技术方法,但面向对象数据库的设计方法却很有价值。本文便以数据库设计以及面向对象数据库的概述为研究基点,分析面向对象数据库的主要特点,并研究在数据库中应用面向对象技术的主要方式,最后讨论面向对象数据库的未来发展。     

Delphi的数据库访问

针对Delphi在数据库开发中的实际情况 ,介绍了Delphi对数据库支持的中间件———数据库引擎BDE ,同时介绍了数据库访问组件和数据库存取组件     

基于Servlet的Web数据库实现

介绍了Web与数据库的三种连接方式,为实现有效的Web数据库架构,主要讨论了应用J2EE的Web服务器端的开发组件Servlet和JDBC数据库连结技术实现Web与Oracle数据库的动态连接,以及JDBC与Oracle数据库的具体连接方法,实现Web数据库的结构模型.为提高Web数据库的存取效率,同时采用数据库连接池技术,实现基于Java的Web数据库,有效地解决和实现Web和数据库的集成,实现Web动态站点.通过实际运行表明,基于Servlet的Web数据库运行稳定、灵活,具有良好的可移植性.     

数据库垄断的成因及对策分析

学术数据库市场被少数几个出版商掌握，新的数据库商难以加入到竞争中来，因此导致了学术数据库市场的垄断问题。本文通过叙述学术数据库垄断的四个问题，即数据库定价的不合理、数据库许可权的滥用、经营者集中和数据库用户受限，提出通过开放获取、图书馆联合与立法保护来应对数据库市场的垄断问题。     

关于Oracle数据库性能优化的分析

持续扩大的数据库规模,用户数量的增多,大大降低了数据库应用系统的响应速度,暴露了很多数据库性能问题。对数据库进行性能优化能促进整个系统的正常运行,提高数据库的稳定性和使用性能,确保数据库的高效运行,提高应用价值。本文针对Oracle数据库性能的一些影响因素,提出一系列优化措施,推动Oracle数据库更好的为人们服务。     

Detecting and removing specularities in facial images

Specularities often confound algorithms designed to solve computer vision tasks such as image segmentation, object detection, and tracking. These tasks usually require color image segmentation to partition an image into regions, where each region corresponds to a particular material. Due to discontinuities resulting from shadows and specularities, a single material is often segmented into several sub-regions. In this paper, a specularity detection and removal technique is proposed that requires no camera calibration or other a priori information regarding the scene. The approach specifically addresses detecting and removing specularities in facial images. The image is first processed by the Luminance Multi-Scale Retinex [B.V. Funt, K. Barnard, M. Brockington, V. Cardei, Luminance-Based Multi-Scale Retinex, AIC’97, Kyoto, Japan, May 1997]. Second, potential specularities are detected and a wavefront is generated outwards from the peak of the specularity to its boundary or until a material boundary has been reached. Upon attaining the specularity boundary, the wavefront contracts inwards while coloring in the specularity until the latter no longer exists. The third step is discussed in a companion paper [M.D. Levine, J. Bhattacharyya, Removing shadows, Pattern Recognition Letters, 26 (2005) 251–265] where a method for detecting and removing shadows has also been introduced. The approach involves training Support Vector Machines to identify shadow boundaries based on their boundary properties. The latter are used to identify shadowed regions in the image and then assign to them the color of non-shadow neighbors of the same material as the shadow. Based on these three steps, we show that more meaningful color image segmentations can be achieved by compensating for illumination using the Illumination Compensation Method proposed in this paper. It is also demonstrated that the accuracy of facial skin detection improves significantly when this illumination compensation approach is used. Finally, we show how illumination compensation can increase the accuracy of face recognition.     

Biomechanical analysis of materials handling manipulators in short distance transfers of moderate mass objects: joint strength,spine forces and muscular antagonism

Although often suggested as a control measure to alleviate musculoskeletal stresses, the use of mechanical assistance devices (i.e. manipulators) in load transfers has not been extensively studied. Without data describing the biomechanical effects of such devices, justification for decisions regarding implementation of such tools is difficult. An experimental study of two types of mechanical manipulators (articulated arm and overhead hoist) was conducted to determine whether biomechanical stresses, and hence injury risk, would be alleviated. Short distance transfers of loads with moderate mass were performed both manually and with manipulator assistance under a variety of task conditions. Using analysis and output from new dynamic torso models, strength demands at the shoulders and low back, lumbar spine forces, and lumbar muscle antagonism were determined. Strength requirements decreased significantly at both the shoulders and low back when using either manipulator in comparison with similar transfers performed manually. Peak spine compression and anteriorposterior (a-p) shear forces were reduced by about 40% on average, and these reductions were shown to be primarily caused by decreases in hand forces and resultant spinal moments. Two metrics of muscular antagonism were defined, and analysis showed that torso muscle antagonism was largest overall when using the hoist. The results overall suggest that hoist-assisted transfers, although better in reducing spine compression forces, may impose relatively higher demands on coordination and/or stability at extreme heights or with torso twisting motions. The relatively higher strength requirements and spine compression associated with the articulated arm may be a result of the high inertia of the system. Potential benefits of practice and training are discussed, and conclusions regarding implementation of mechanical manipulators are given.     

A numerical model for the winter circulation in Lake Trichonis, Greece

Progress in the understanding and eventual management of lakes depends upon iterative interactions between model-guided measurements and measurement-tested model development. A research example of this progress can be demonstrated by the measurement campaigns that were mounted in Lake Trichonis, in central Greece. Numerical simulations and analytical theories have been tested against currents, surface seiche and temperatures. Simultaneous water gauges, current meters, anemometric stations, thermometers, sediment and water samplers were used for the verification of the model. The agreement between the theoretically predicted and experimentally determined data was satisfactory for most of the verifications. The most significant error was due to atmospheric pressure. The computed surface seiche showed excellent agreement with the observations, even in spectral analysis. The computed currents showed circulation patterns very similar to those measured in the field. The computed temperature distributions throughout the lake were not in good agreement because of incoming water from the bottom.     

基于属性优先关系的多用户Skyline查询处理算法#br#

Skyline查询为多目标决策等问题提供了解决方案。每个用户对数据属性的优先关系的需求不同,传统算法无法有效解决多用户场景下的偏好Skyline查询。针对该问题,提出一种基于属性优先关系的多用户偏好Skyline查询算法--MUPS算法。该算法基于属性权重对原始Skyline结果集通过新的σ-支配方式进行剪枝;同时,通过交互动态修正属性的权重大小,使最终结果更符合用户群的真实偏好需求。最后,在模拟和真实数据上验证MUPS算法的有效性和良好的交互性能。     

Query rewritings using views for XPath queries,framework, and methodologies

Query rewriting using views is a technique that allows a query to be answered efficiently by using pre-computed materialized views. It has many applications, such as data caching, query optimization, schema integration, etc. This issue has been studied extensively for relational databases and, as a result, the technology is maturing. For XML data, however, the work is inadequate. Recently, several frameworks have been proposed for query rewriting using views for XPath queries, with the requirement that a rewriting must be complete. In this paper, we study the problem of query rewriting using views for XPath queries without requiring that the rewriting be complete. This will increase its applicability since in many cases, complete rewritings using views do not exist. We give formal definitions for various concepts to formulate the problem, and then propose solutions. Our solutions are built under the framework for query containment. We look into the problem from both theoretic perspectives, and algorithmic approaches. Two methods to generate rewritings using views are proposed, with different characteristics in terms of generalities and efficiencies. The maximality properties of the rewritings generated by these methods are discussed.     

Parallel Fiber Coding in the Cerebellum for Life-Long Learning

Continuous and real-time learning is a difficult problem in robotics. To learn efficiently, it is important to recognize the current situation and learn appropriately for that context. To be effective, this requires the integration of a large number of sensorimotor and cognitive signals. So far, few principles on how to perform this integration have been proposed. Another limitation is the difficulty to include the complete contextual information to avoid destructive interference while learning different tasks.We suggest that a vertebrate brain structure important for sensorimotor coordination, the cerebellum, may provide answers to these difficult problems. We investigate how learning in the input layer of the cerebellum may successfully encode contextual knowledge in a representation useful for coordination and life-long learning. We propose that a sparsely-distributed and statistically-independent representation provides a valid criterion for the self-organizing classification and integration of context signals. A biologically motivated unsupervised learning algorithm that approximate such a representation is derived from maximum likelihood. This representation is beneficial for learning in the cerebellum by simplifying the credit assignment problem between what must be learned and the relevant signals in the current context for learning it. Due to its statistical independence, this representation is also beneficial for life-long learning by reducing the destructive interference across tasks, while retaining the ability to generalize. The benefits of the learning algorithm are investigated in a spiking model that learns to generate predictive smooth pursuit eye movements to follow target trajectories.     

Constrained and SNR-Based Solutions for TV-Hilbert Space Image Denoising

We examine the general regularization model which is based on total-variation for the structural part and a Hilbert-space norm for the oscillatory part. This framework generalizes the Rudin-Osher-Fatemi and the Osher-Sole-Vese models and opens way for new denoising or decomposition methods with tunable norms, which are adapted to the nature of the noise or textures of the image. We give sufficient conditions and prove the convergence of an iterative numerical implementation, following Chambolle’s projection algorithm. In this paper we focus on the denoising problem. In order to provide an automatic solution, a systematic method for choosing the weight between the energies is imperative. The classical method for selecting the weight parameter according to the noise variance is reformulated in a Hilbert space sense. Moreover, we generalize a recent study of Gilboa-Sochen-Zeevi where the weight parameter is selected such that the denoised result is close to optimal, in the SNR sense. A broader definition of SNR, which is frequency weighted, is formulated in the context of inner products. A necessary condition for maximal SNR is provided. Lower and upper bounds on the SNR performance of the classical and optimal strategies are established, under quite general assumptions.     

第四代GIS软件研究

地理信息系统是国家空间数据基础设施建设的重要组成部分,对国民经济建设和国家安全有着重要的意义,文中总结了GIS软件的发展历史与技术特点,结合IT技术的发展,指出了现有软件存在的不足,并分析了技术原因,根括了第四代GIS软件的研究目标和技术体系,提出了发展我国第四代GIS软件步骤的建议。     

Process Control in metallurgical plants—From an Xstrata perspective

Some history and modern practice of Process Control in metallurgical operations is reviewed. Clearly the early deliverables from the pioneer days in the 1950s through to the 1970s and early 1980s were under-appreciated. The discipline has since grown into a more visible, sophisticated and accepted practice as a result of the assembly of appropriately recruited and trained individuals and teams, who have successfully negotiated deliverable projects that impact all metallurgical performances beyond early milling processes. The skill set in these individuals and teams essentially includes organisational behaviour in addition to their specialist technical attributes. A strong network to internal and external specialists and experts is essential. Furthermore, instrumentation and control technology has improved immensely. The challenge in the current modern practice is to win support of senior management in operations for the project cost, schedule and deliverables of Process Control. Once gained, this acceptance then amounts to the logistics of project scope and delivery—a track record well-demonstrated by the Xstrata Process Control Group.