XML在关系数据库应用中的性能问题探究

探讨了XML在关系型数据库应用中的优缺点,并着重在数据库性能方面进行实例探究。通过使用．net framework设计具体测试程序,实际考察了XML和常见关系数据库（本文主要以最新的SQL Server 2005为例）在增删改等操作时,性能上的差异（本文的实验仅仅用于单用户操作）。     

Improving Generalization with Active Learning

Active learning differs from learning from examples in that the learning algorithm assumes at least some control over what part of the input domain it receives information about. In some situations, active learning is provably more powerful than learning from examples alone, giving better generalization for a fixed number of training examples.In this article, we consider the problem of learning a binary concept in the absence of noise. We describe a formalism for active concept learning calledselective sampling and show how it may be approximately implemented by a neural network. In selective sampling, a learner receives distribution information from the environment and queries an oracle on parts of the domain it considers useful. We test our implementation, called anSG-network, on three domains and observe significant improvement in generalization.A preliminary version of this article appears as Cohn et al. (1990).     

Electrochemical process for the lamination of magnetic cores in thin-film magnetic components

The lamination of the core in thin film magnetic components is necessary to reduce the eddy current losses of the structure at high frequencies. The usual way to achieve lamination of the core is by physical vapor deposition (PVD) techniques. These methods are however costly and the deposition of layers is non selective. In this article, an almost entirely aqueous-based electrochemical process for the lamination of magnetic cores is presented. The process uses an electrodepositable photoresist Eagle 2100 ED codeposited with a catalyst (palladium). The Eagle layer is left as an insulator and the catalyst allows the activation of the layer for subsequent metallization. The process can be reproduced as many times as required for producing the multilayers. It is also selective: it does not require multiple photolithography steps. As a demonstration of the multilayer process, a core constituted of two layers of Ni/sub 80/Fe/sub 20/ (6 /spl mu/m each layer), separated by an Eagle insulating layer, electroplated over three-dimensional structures, was produced.     

一种脉冲编码器结合GPS的精确动态定位装置

介绍了一种脉冲编码器结合GPS的定位装置。该装置可用于对运动体进行精确动态定位。与现有技术相比，该装置利用GPS和脉冲编码器的配合进行高精度动态定位，达到厘米级的定位精度，并且在GPS数据失效的情况下，仍然能够满足精度要求，该装置广泛适用于对运动体进行高精度定位。     

What can the history of AI learn from the history of science?

There have been few attempts, so far, to document the history of artificial intelligence. It is argued that the historical sociology of scientific knowledge can provide a broad historiographical approach for the history of AI, particularly as it has proved fruitful within the history of science in recent years. The article shows how the sociology of knowledge can inform and enrich four types of project within the history of AI; organizational history; AI viewed as technology; AI viewed as cognitive science and historical biography. In the latter area the historical treatments of Darwin and Turing are compared to warn against the pitfalls of rational reconstructions of the past.     

A Reinforcement Learning Scheme for a Partially-Observable Multi-Agent Game

We formulate an automatic strategy acquisition problem for the multi-agent card game Hearts as a reinforcement learning problem. The problem can approximately be dealt with in the framework of a partially observable Markov decision process (POMDP) for a single-agent system. Hearts is an example of imperfect information games, which are more difficult to deal with than perfect information games. A POMDP is a decision problem that includes a process for estimating unobservable state variables. By regarding missing information as unobservable state variables, an imperfect information game can be formulated as a POMDP. However, the game of Hearts is a realistic problem that has a huge number of possible states, even when it is approximated as a single-agent system. Therefore, further approximation is necessary to make the strategy acquisition problem tractable. This article presents an approximation method based on estimating unobservable state variables and predicting the actions of the other agents. Simulation results show that our reinforcement learning method is applicable to such a difficult multi-agent problem.Editor Risto Miikkulainen     

Tutoring bishop-pawn endgames: An experiment in using knowledge-based chess as a domain for intelligent tutoring

Most research in computer chess has focused on creating an excellent chess player, with relatively little concern given to modeling how humans play chess. The research reported in this article is aimed at investigating knowledge-based chess in the context of building a prototype chess tutor, UMRAO, which helps students learn how to play bishop-pawn endgames. In tutoring it is essential to take a knowledge-based approach, since students must learn how to manipulate strategic concepts, not how to carry out large-scale lookahead searches.UMRAO uses an extension of Michie's advice language to represent expert and novice chess plans. For any given endgame, the system is able to compile the plans into a strategy graph, which elaborates strategies (both well formed and ill formed) that students might use as they solve the endgame problem. A strategy graph can be compiled off-line, where real-time performance is not important. Later, during tutoring, the strategy graph can be accessed quickly in order to understand a student's moves in terms of his or her strategies. With such understanding, UMRAO is able to provide appropriate knowledge-based feedback to the student. Anderson et al. have called this tutoring paradigm model tracing, but in the chess domain model tracing can be used without the need for immediate feedback that Anderson has required in his more complex abstract problem-solving domains. The chess domain thus allows experimentation with a variety of tutoring styles that range from immediate feedback to optional feedback, from strict tutor control of the feedback to student initiative in the choice of feedback. This points out UMRAO's most promising contribution: re-establishing chess as a vehicle for research in other areas of artificial intelligence, in this case intelligent tutoring systems. UMRAO also makes technical contributions to knowledge-based chess and to intelligent tutoring as well.     

Finding keywords in blogs: Efficient keyword extraction in blog mining via user behaviors

Readers are becoming accustomed to obtaining useful and reliable information from bloggers. To make access to the vastly increasing resource of blogs more effective, clustering is useful. Results of the literature review suggest that using linking information, keywords, or tags/categories to calculate similarity is critical for clustering. Keywords are commonly retrieved from the full text, which can be a time-consuming task if multiple articles must be processed. For tags/categories, there is also a problem of ambiguity; that is, different bloggers may define tags/categories of identical content differently. Keywords are important not only to reflect the theme of an article through blog readers’ perspectives but also to accurately match users’ intentions. In this paper, a tracing code is embedded in Blog Connect, a newly developed platform, to collect the keywords queried by readers and then select candidate keywords as co-keywords. The experiments show positive data to confirm that co-keywords can act as a quick path to an article. In addition, co-keyword generation can reduce the complexity and redundancy of full-text keyword retrieval procedures and satisfy blog readers’ intentions.     

Secure Hamming distance computation for biometrics using ideal-lattice and ring-LWE homomorphic encryption

With widespread development of biometrics, concerns about security and privacy are rapidly increasing. Homomorphic encryption enables us to operate on encrypted data without decryption, and it can be applied to construct a privacy-preserving biometric system. In this article, we apply two homomorphic encryption schemes based on ideal-lattice and ring-LWE (Learning with Errors), which both have homomorphic correctness over the ring of integers of a cyclotomic field. We compare the two schemes in applying them to privacy-preserving biometrics. In biometrics, the Hamming distance is used as a metric to compare two biometric feature vectors for authentication. We propose an efficient method for secure Hamming distance. Our method can pack a biometric feature vector into a single ciphertext, and it enables efficient computation of secure Hamming distance over our packed ciphertexts.     

Writing Centers and Students with Disabilities: The User-centered Approach,Participatory Design,and Empirical Research as Collaborative Methodologies

This article discusses issues of accessibility and how user-centered and participatory approaches can inform empirical research to guide the Universal Design of virtual spaces and influence writing center efforts for students with disabilities. Because this article describes how to integrate usability/accessibility testing for online and in-person services, it can work as a model for writing centers struggling with the challenges of serving students with disabilities. Toward this end, the article discusses two generations of usability testing on a large, well-established online writing lab (the Purdue OWL), as well as the collaborative projects that emerged between the usability team and campus disabilities services as a result of this testing. The article concludes with heuristics and generative questions that may assist readers in developing similar projects tailored to their own contexts.     

Real-Time Supervisory Control of a Processor for Non-Preemptive Execution of Periodic Tasks

In this article, a method for scheduling a processor for non-preemptive execution of periodic tasks is presented. This method is based on the formal framework of supervisory control of timed discrete-event systems. It is shown that, with this method, the problem of determining schedulability and the problem of finding a scheduling algorithm are dual since a solution to the former necessarily implies a solution to the latter and vice versa. Furthermore, the solution to the latter thus obtained is complete in the sense that it contains all safe sequences of task execution with the guarantee that no deadline is missed. Examples are described to illustrate this method. Implication of the results and computational complexity associated with this method are discussed.     

Controlled Thermophoresis as an Actuation Mechanism for Noncantilevered MEMS Devices

A microelectromechanical system actuator based on thermophoretic, or Knudson, forces is proposed using analytical calculations. It can potentially execute scanning or spinning motions of a body that is not mechanically attached to the reference substrate. For a silicon device of 100-$muhbox{m}$ diameter, it is calculated that it can be levitated at a distance of about 0.5 $muhbox{m}$ from a substrate and that it can execute scanning motion and use quasi-springs by laterally acting thermal forces. In this way, an engine with spinning motion of a floating body having a diameter of 200 $muhbox{m}$ with up to 5 kHz can be achieved.$hfill$[2008-0013]      

An expert system development tool for non AI experts

From their first applications until now, expert systems have provided solutions to multiple problems in companies of all types. With the advent of the Internet and its evolution, web-based expert systems have become very important. Moreover, the arrival of new mobile devices that can connect to the Internet has made it easy to access information from any place at any time, creating new requirements for web systems. The creation of an expert system normally requires certain technical knowledge and concepts of artificial intelligence (AI). If the need to make it accessible through the Internet is added, the degree of technical knowledge necessary for its development is greater, entailing an unaffordable cost for small and medium-sized companies. In this article, we present a tool for the development of web-based expert systems which permits the expert to define the knowledge without having to know anything about AI. The proposed inference engine is integrated in a web server through which it can be accessed from any device with an Internet connection. Finally, the article presents examples of developments achieved via the proposed framework.     

Force-guided motions of a 6-d.o.f. industrial robot with a joint space approach

This article deals with the interaction between humans and industrial robots, more specifically with the new design and implementation of an algorithm for force-guided motions of a 6-d.o.f. robot. It may be used to comfortably teach positions without using any teaching pendant or for some assistance tasks. For this purpose, from readings of the force/torque sensor mounted in the robot wrist, the gravity forces and torques first have to be eliminated. To control the robot in joint space, it is then convenient to transform the external force and torque values from Cartesian space into joint space using the manipulator transposed Jacobian. This is why with the present approach the Jacobian matrix of the robot used was calculated. Now, from the computed joint torques, suitable position commands of the robot arm can be generated to obtain the desired behavior. A suggestion for this desired behavior is also included in this article. It is based on the impedance control approach in joint space. The proposed algorithm was implemented with the standard Stäubli RX90B industrial robot.     

以代理为中心的OSGi构件资源监控方法

基于构件的软件开发和复用是提高软件开发效率和质量的有效途径,OSGi(open services gateway initiative)构件平台模型为软件构件提供了良好的生命周期管理和动态依赖管理。在构件粒度上对系统的资源进行监控能够有效增强系统的可靠性,然而目前针对OSGi平台的构件资源监控技术侧重于统计整个系统的资源消耗,未能把统计的粒度细化到构件上,且不能根据各个构件的资源消耗情况对系统进行调整。提出一种基于代理的OSGi构件资源监控方法。该方法具有以下特点:在构件粒度上统计系统的资源消耗,能够统计到每一个构件所消耗的内存和CPU时间;能够发现资源消耗异常的构件,并对其进行重启或替换,从而提高系统可靠性;具有非侵入性,即不会对构件进行任何修改,不会影响到第三方应用的逻辑结构。实验表明,该方法可以准确地统计到构件的资源消耗量,并据此对构件进行有效的调整,提高系统的可靠性。     

针对经典排序问题的一种新算法的近似比分析

给定m台平行机(同型机),n个工件,寻找一种分配方案,使得把这n个工件分配到m台机器后,整体完工时间尽可能短,这个NP-难问题被称为经典排序问题。如果每个工件的加工时间满足一定的条件,则有望能在多项式时间内有效地得到最优的分配方案。Yue等对加工时间满足整除性质的经典排序问题考虑了一种新的算法,该算法总是能得到这种特殊情况的最优分配。该算法在多项式时间内能够得到最优分配,是对于一般的经典排序问题的近似算法。文章在此基础上,考虑该新算法在一般问题上的近似比。文中考虑了这个新算法的两种版本,分别得到了3/2和2-1/2 ^q(q∈Z⁺)的近似比。紧例子表明,文中对算法的两个版本的分析都是最优的。     

一种用于声纳系统的高速数据实时存储系统

在声纳工程领域,试验数据都是不可多得的宝贵资料,因此经常需要对大量数据进行实时存储。Windows操作系统能在一定程度上满足大量数据的存储,但实时性不够好。本文提出了一种基于嵌入式实时操作系统VxWorks的海量数据存储方法,并解决了大硬盘的I/O访问、数据在Windows操作系统下转存的问题,这些方法都已经得到了实际的应用。     

Existence and Computation of Low Kronecker-Rank Approximations for Large Linear Systems of Tensor Product Structure

In this paper we construct an approximation to the solution x of a linear system of equations Ax=b of tensor product structure as it typically arises for finite element and finite difference discretisations of partial differential operators on tensor grids. For a right-hand side b of tensor product structure we can prove that the solution x can be approximated by a sum of (log()²) tensor product vectors where is the relative approximation error. Numerical examples for systems of size 1024²⁵⁶ indicate that this method is suitable for high-dimensional problems.     

一种敏感低加速度的碰撞开关

介绍了一种可以敏感低加速度值的碰撞开关 ,讨论了其理论建模方法及相关内容 ,并从理论、设计和试验方面对冲击响应情况进行了初步分析。该开关的作用门限为 10 0m/s2 ,响应时间为 10ms,可以作为主触发引信应用于某常规武器中 ,其结构和设计方法也可供炮弹、导弹引信用惯性冲击传感器设计人员参考。     

Spatiotemporal mapping of a large mountain glacier from CryoSat-2 altimeter data: surface elevation and elevation change of Bering Glacier during surge (2011–2014)

CryoSat-2 radar altimeter data have been applied to map surface elevations of the Greenland and Antarctic ice sheets, and of Arctic icecaps. In this article we investigate the feasibility of using CryoSat-2 data for spatiotemporal analysis of surface elevation of a large mountain glacier. Bering Glacier, Alaska (which is 8–20 km wide and approximately 80 km long) is selected as a study area because it surges and hence shows short-term elevation changes. The approach includes a correction method, geostatistical analysis, and several methods for error assessment. A time series of digital elevation models (DEMs) is derived for six-month increments from Summer 2011 to Winter 2013/2014. DEMs have, on average, numerical Kriging errors of 1.65 + 3.19 m and Kriging estimation standard deviations of 11.32 + 1.01 m. A crossover analysis with airborne laser altimeter data from the fall months of 2011, 2012, and 2013 produced differences of 5.03 + 13.67 m compared to respective CryoSat-2 data sets. Difference maps are derived from the DEMs and are used to infer dynamical changes associated with the recent surge. In conclusion, CryoSat-2 data can be employed for spatiotemporal mapping of the evolution of surface elevation in Bering Glacier and other mountain glaciers of similar width, while providing key insight into large-scale elevation change over relatively short time periods.