Overflow control for cellular mobility database

In a cellular phone system, the service area is partitioned into several location areas (LAs). Every LA is associated with a mobility database called visitor location register (VLR). When a mobile user enters an LA, the user must register to the VLR before receiving any cellular service. If the VLR is full, the registration procedure fails and the system cannot deliver services to the user under the existing cellular technology. To resolve this problem, we propose a VLR overflow control scheme to accommodate the incoming mobile users during VLR overflow. Our scheme only requires minor modifications to the existing cellular mobility management protocols. Particularly, no modification is made to the mobile phones. An analytic model is proposed to investigate the performance of the overflow control scheme. When exercising the scheme, the call setup procedure for an “overflow” user is more expensive than that for a “normal” user. Under the range of input parameters considered in our study, we show that even if the VLR overflow situation is serious, the overhead for exercising the overflow control scheme is very low     

Hierarchical replication and multiversion concurrency control model for mobile database systems (MDS)

In mobile ad hoc network, the existing replication technique and multiversion scheme increase the cost of overhead. In addition, there is possibility of mobility- and energy-related issues. In order to overcome these issues, in this paper, we propose a hierarchical replication and multiversion concurrency control model for mobile database systems. In this technique, cluster heads (CHs) are selected based on the distance from the past node movements. When the client raises a query, the database server distributes the replicated data to the nearer cluster heads. When any CH observes that one of its members is about to move, then it suggests the nearest cluster having the same data object to the moving client, so that it can quickly access the data during its movement. For concurrency control, each CH maintains a concurrency table for each of its replicated data object. By simulation results, we show that the proposed technique reduces the overhead and energy consumption.     

Per-user checkpointing for mobility database failure restoration

This paper studies the failure restoration of mobility database for Universal Mobile Telecommunications System (UMTS). We consider a per-user checkpointing approach for the home location register (HLR) database. In this approach, individual HLR records are saved into a backup database from time to time. When a failure occurs, the backup record is restored back to the mobility database. We first describe a commonly used basic checkpoint algorithm. Then, we propose a new checkpoint algorithm. An analytic model is developed to compare these two algorithms in terms of the checkpoint cost and the probability that an HLR backup record is obsolete. This analytic model is validated against simulation experiments. Numerical examples indicate that our new algorithm may significantly outperform the basic algorithm in terms of both performance measures.     

视频数据库多级访问控制

针对视频数据库中涉及敏感信息的视频数据分级保护问题,提出视频数据库多级访问控制模型。在该模型中,设计用户身份辨别及身份强度算法,其结果作为用户安全等级隶属函数的输入,该函数值为用户安全等级隶属度,并与视频数据安全等级隶属度一起作为授权规则中安全等级隶属度比较函数的输入,其函数值结合时间元素能够灵活地实现多级访问控制。与已有的访问控制模型相比,该模型最突出的特点是实现动态授权和视频数据分级保护。     

Hierarchical fuzzy force control for industrial robots

In this paper, we present a hierarchical force control framework consisting of a high-level control system based on fuzzy logic and the existing motion control system of a manipulator in the low level. In order to adapt various contact conditions, an adaptable fuzzy force control scheme has been proposed to improve the performance. The ability of the adaptable force control system is achieved by tuning the scaling factor of the fuzzy logic controller (FLC). A Mitsubishi MELFA RV-M1 industrial robot equipped with a BL Force/Torque sensor is utilized for implementing the hierarchical fuzzy force control system. Successful experiments for various contact motions are carried out. Additionally, discussion of a peg-in-hole insertion is presented, and the experimental results are given     

Hierarchical mobility management for fast handoff and load distribution in IPv6 networks

Hierarchical Mobile IPv6 (HMIPv6) has been proposed by the Internet engineering task force (IETF) to compensate for such problems as handover latency and signalling overhead when employing Mobile IPv6 (MIPv6). HMIPv6 supports micro‐mobility within a domain and introduces a new entity, namely mobility anchor point (MAP) as a local home agent (HA). However, HMIPv6 has caused load concentration at a particular MAP and longer handover latency when an inter‐domain handover occurs. In order to solve such problems, this paper establishes a virtual domain (VD) of a higher layer MAP and proposes a MAP changing scheme. The MAP changing scheme enables complete handover by using binding‐update of the on‐link care of address (LCoA) only when inter‐domain handover occurs. In addition, the concentrated load of a particular MAP is distributed as well. Copyright © 2008 John Wiley & Sons, Ltd.     

Hierarchical optimal contour control of motion systems

Many motion control applications utilize multiple axes to traverse complex trajectories. The hierarchical contour control methodology proposed in this paper treats each axis as an individual subsystem and combines the Internal Model Principle with robust tracking and optimal hierarchical control techniques to track a desired trajectory. In this method the objectives are divided into two levels. Measurable goals of each subsystem are included in the bottom level and unmeasurable goals, which are estimated using the bottom level states, are considered in the top level where the subsystems are synchronized. The proposed methodology reduces system complexity while greatly improving tracking performance. The tracking error for each axis is considered in the bottom level where the Internal Model Principle is used to compensate for unmodeled nonlinear friction and slowly varying uncertainties. The top level goal (i.e., zero contour error) is propagated to the lower level by an aggregation relationship between contour error and physical linear axis variables. A controller is designed at the bottom level which simultaneously satisfies the bottom level goals (i.e., individual axis tracking) and the top level goal. Experimental results implemented on a table top CNC machine for diamond and freeform contours illustrate the performance of the proposed methodology. While this methodology was implemented for a two-axis motion system, it can be extended to any motion system containing more than two axes.     

An analysis of location record checkpointing interval for mobility database in PCS networks

Mobility database that stores the users’ location records is very important to connect calls to mobile users on personal communication networks. If the mobility database fails, calls to mobile users may not be set up in time. This paper studies failure restoration of mobility database. We study per-user location record checkpointing schemes that checkpoint a user’s record into a non-volatile storage from time to time on a per-user basis. When the mobility database fails, the user location records can be restored from the backup storage. Numeric analysis has been used to choose the optimum checkpointing interval so that the overall cost is minimized. The cost function that we consider includes the cost of checkpointing a user’s location record and the cost of paging a user due to an invalid location record. Our results indicate that when user registration intervals are exponentially distributed, the user record should never be checkpointed if checkpointing costs more than paging. Otherwise, if paging costs more, the user record should be always checkpointed when a user registers.     

书目数据库质量控制及维护

结合黑龙江大学图书馆书目数据库建设和发展,论述书目数据质量控制在图书馆自动化以及文献资源共享中的重要性,指出书目数据库的标准化、规范化、高质量是图书馆之间进一行书目信息交换与资源共享的前提条件.书目数据库标准化是构建文献资源保障系统的基本条件之一,也是网上数据库的核心.并强调加强数据库维护工作的重要性.     

分层递阶控制理论与电力系统自动化研究

随着科学技术及电力设计的发展,电力系统的自动化水平日益提高,智能控制技术在电力系统中的应用越越来越深入。本文分析了分层递阶控制理论与电力系统智能化之间的联系,以及相似的理论与实践间的相互促进关系。并在电力控制系统中引入了仿人智能控制理论,分析了职能技术在电力自动化系统中的应用。     

A distributed mobility control scheme in LISP networks

The locator identifier separation protocol (LISP) has been made as an identifier-locator separation scheme for scalable Internet routing. However, the LISP was originally designed for fixed network environment, rather than for mobile network environment. In particular, the existing LISP mobility control schemes use a centralized map server to process all the control traffics, and thus they are intrinsically subject to some limitations in mobile environment, such as large overhead of mapping control traffics at central map server and degradation of handover performance. To overcome these problems, we propose a distributed mobility control scheme in LISP networks. In the proposed scheme, we assume that a mobile host has a hierarchical endpoint identifier which contains the information of its home network domain. Each domain has a distributed map server (DMS) for distributed mapping management of Endpoint Identifiers (EIDs) and Locators (LOCs). For roaming support, each DMS maintains a home EID register and a visiting EID register which are used to keep the EID-LOC mappings for mobile hosts in the distributed manner. For performance analysis, we compare the control traffic overhead (CTO) at map servers, the signaling delay required for EID-LOC mapping management, and the handover delay for the existing and proposed schemes. From numerical results, it is shown that the proposed distributed scheme can give better performance than the existing centralized schemes in terms of CTO, total signaling delay for EID-LOC mapping management, and handover delay.     

Research on HLR mobility database failure recovery and performance analysis for CDMA2000 systems

In this paper, a novel Home Location Register(HLR) mobility database recovery scheme is proposed. With database backing-up and signal sending as its key processes, the presented scheme is designed for the purpose of both decreasing system costs and reducing number of lost calls. In our scheme, an algorithm is developed for an HLR to identify such VLRs that there are new MSs roaming into them since the latest HLR database backing up. The identification of those VLRs is used by the HLR to send Unreliable Roaming Data Directive messages to each of them to get the correct location information of those new MSs.Additionally, two kinds of relationships, one between the number of lost calls and the database backing-up period and the other between the backing-up cost and the period, are well analyzed. Both analytical and numerical results indicate that there will be an optimal HLR database backing-up period if certain system parameters are given and the total cost can be consequently minimized.     

面向数据库清洗的数据质量控制设计

信息处理技术的不断变革,使每个行业都拥有了许多计算机信息系统,同时也产生了大量的数据。因此能够使数据有效地进行组织的日常运作和判断,要求数据可靠准确是研究的热点,文中提出了一种ETL与数据清洗结合的分布式数据集成工具,将数据清理的技术引入到ETL中,制定数据清洗规则,并基于统计的方法,聚类方法,关联规则的方法等提出数据清洗的算法,并进行比较,提出清洗数据信息的框架,从而提高数据的质量,进行数据清洗评估,认为方法可行有效,具有实际应用意义。     

基于JADE的数据库自适应负载控制分析

传统DBA数据库控制方法对系统参数进行设置和配置时,存在控制效率低以及能耗高的问题。提出基于JADE的数据库自适应负载控制方法,设计以JADE平台为基础的数据库自适应负载控制系统。系统由搜索和查询两部分构成,通过Agent之间相互协作来完成总体系统的负载控制。通过数据库爬虫Agent在数据库中搜集信息,形成原始数据库;应用KNN算法对原始数据库进行分类,实现数据库负载控制。查询部分通过JSP页面中的用户接口Agent实现与用户的交互;采用JDBC桥技术实现查询Agent对数据库的访问。实验结果表明,采用所提方法控制数据库负载,可提高数据库的实现价值、吞吐率以及资源利用率。     

Application of soft computing techniques to adaptive user buffer overflow control on the Internet

Two novel expert dynamic buffer tuners/controllers, namely, the neural network controller (NNC) and the fuzzy logic controller (FLC) are proposed in this paper. They use soft computing techniques to eliminate buffer overflow at the user/server level. As a result they help shorten the end-to-end service roundtrip time (RTT) of the logical Internet transmission control protocol (TCP) channels. The tuners achieve their goal by maintaining the given safety margin /spl Delta/ around the reference point of the {0,/spl Delta/}/sup 2/ objective function. Overflow prevention at the Internet system level, which includes the logical channels and their underlying activities, cannot shorten the service RTT alone. In reality, unpredictable incoming request rates and/or traffic patterns could still cause user-level overflow. The client/server interaction over a logical channel is usually an asymmetric rendezvous, with one server serving many clients. A sudden influx of simultaneous requests from these clients easily inundates the server's buffer, causing overflow. If this occurs only after the system has employed expensive throttling and overflow management resources, the delayed overflow rectification could lead to serious consequences. Therefore, it makes sense to deploy an independent user-level overflow control mechanism to complement the preventative effort by the system. Together they form a unified solution to effectively stifle channel buffer overflow.     

数据库技术在计算机控制中的应用与研究

信息时代下,借助大数据技术能够实现对海量数据信息的优化应用,推动社会现代化进程发展.而大数据分析已经成为计算机技术的应用发展关键技术之一,通过在计算机控制系统中搭建数据库是实现大数据技术广泛应用的重要途径.文章对数据库技术在计算机控制中的应用现状进行阐述,旨在能够在总结经验的基础上更好地提高数据库技术应用的最优效益.     

工业控制系统的实时数据库设计

分析了工业控制系统的实时数据库的特点和需求 ,通过与普通数据库的比较 ,从数据模型、存储结构和介质、存取方式和途径以及完整性和一致性的维护等角度分析了实时数据库的设计方法。     

嵌入式数据库SQLite在测控系统设计中的应用

基于嵌入式数据库SQLite3.0技术设计了一个新的测控系统。该系统以嵌入式服务器为核心,把现场采集到的数据,加工处理后发布到网络中,供远程用户及时浏览和查看。文中分析了嵌入式数据库的特点和关键技术,并且在此基础上,着重研究了SQLite3.0数据库的内部结构、应用方式和移植方法。该技术以SQLite3.0为后台,进行...