VideoCD播放系统设计

目前国内外正在出现开发ＶｉｄｅｏＣＤ系列产品的热潮，就象几年前从磁带录音机转向激光唱机那样，呈现一种从录象机转向数字视盘播放机的趋势，本文的前半部分介绍设计ＶｉｄｅｏＣＤ播放系统要涉及到的重要标准，着重解释了ＷｈｉｔｅＢｏｏｋ和ＭＰＥＧ压缩算法；后半部分阐述播放系统的设计方案和策略，详细说明国内潜在市场很大的ＶｉｅｄｏＣＤ播放机设计方案。     

四进制只读光频存储器的设计

主要介绍了如何用颜色进行四进制数据存储，以及用光信号作为信息媒介的好处。重新定义了一些四进制的运算法则，同时介绍了如何利用这种存储格式进行四进制或者二进制通信与控制的方法。最后介绍了四进制在工程技术中的一些重要应用，总结了数据存储的本质，从而为将来用其他方式实现数据存储打下了比较坚实的基础。     

面向存储介质的数据安全删除

随着信息通信技术的快速发展,存储介质中的信息量显著增加,这些信息的长期存储容易导致隐私泄露,仅仅删除存储介质文件索引表无法达到彻底删除的目的,具有一定的安全隐患,如何保护存储介质中的信息隐私安全备受关注.针对上述问题,首先介绍安全删除相关的基础知识,包括存储介质的基本结构、存储原理和删除原理;然后分析主流的数据安全删除标准,并研究这些标准的特性;最后,设计与实现一种能够达到数据不可恢复的安全删除原型系统,并对现有数据删除软件进行测试与分析.结果表明所开发原型系统能够实现存储介质中的数据安全删除,有效保护数据安全与隐私.     

Storing pictures for different purposes

There are many arguments put forward as to how packages should store their graphical data for subsequent use and/or transfer to another system or package. These discussions are not unique, but are particularly important, to CAE applications. This paper looks at the different requirements for the storage of pictures. It suggests that the arguments put forward are not as emotive as are often suggested. There are different solutions for different requirements. There is a need for various methods of storage in a CAE package. The important thing from a designer's point of view is to ensure that the correct storage method is adopted for a particular need. The discussions presented here build on the papers in the special issue of Computer-Aided Design that considered graphics standards. The papers of particular interest are those by Arnold, Owen and Bloor and Mumford.     

Knowledge discovery standards

As knowledge discovery (KD) matures and enters the mainstream, there is an onus on the technology developers to provide the technology in a deployable, embeddable form. This transition from a stand-alone technology, in the control of the knowledgeable few, to a widely accessible and usable technology will require the development of standards. These standards need to be designed to address various aspects of KD ranging from the actual process of applying the technology in a business environment, so as to make the process more transparent and repeatable, through to the representation of knowledge generated and the support for application developers. The large variety of data and model formats that researchers and practitioners have to deal with and the lack of procedural support in KD have prompted a number of standardization efforts in recent years, led by industry and supported by the KD community at large. This paper provides an overview of the most prominent of these standards and highlights how they relate to each other using some example applications of these standards.     

The value of handhelds in smart environments

The severe resource restrictions of computer-augmented everyday artifacts imply substantial problems for the design of applications in smart environments. Some of these problems can be overcome by exploiting the resources, I/O interfaces, and computing capabilities of nearby mobile devices in an ad-hoc fashion. We identify the means by which smart objects can make use of handheld devices such as PDAs and mobile phones, and derive the following major roles of handhelds in smart environments: (1) mobile infrastructure access point; (2) user interface; (3) remote sensor; (4) mobile storage medium; (5) remote resource provider; and (6) weak user identifier. We present concrete applications that illustrate these roles, and describe how handhelds can serve as mobile mediators between computer-augmented everyday artifacts, their users, and background infrastructure services. The presented applications include a remote interaction scenario, a smart medicine cabinet, and an inventory monitoring application.     

非易失性内存安全技术综述

大数据应用对内存容量的需求越来越大,而在大数据应用中,以动态随机存储器为内存介质的传统存储器所凸显出来的问题也越来越严重。计算机设计者们开始考虑用非易失性内存去替代传统的动态随机存储器内存。非易失性内存作为非易失的存储介质,不需要动态刷新,因此不会引起大量的能量消耗;此外,非易失性内存的读性能与动态随机存储器相近,且非易失性内存单个存储单元的容量具有较强的可扩展性。但将非易失性内存作为内存集成到现有的计算机系统中,需要解决其安全性问题。传统的动态随机存储器作为内存介质掉电后数据会自动丢失,即数据不会在存储介质中驻留较长时间,而当非易失性内存作为非易失性存储介质时,数据可以保留相对较久的时间。若攻击者获得了非易失性内存存储器的访问权,扫描存储内容,便可以获取内存中的数据,这一安全性问题被定义为数据的“恢复漏洞”。因此,在基于非易失性内存模组的数据中心环境中,如何充分有效地利用非易失性内存,并保证其安全性,成为迫切需要解决的问题。该文从非易失性内存的安全层面出发,对近年来的研究热点及进展进行介绍。首先,该文总结了非易失性内存所面临的主要安全问题,如数据窃取、完整性破坏、数据一致性与崩溃恢复...     

An Overview of Standards and Related Technology in Web Services

The Internet is revolutionizing business by providing an affordable and efficient way to link companies with their partners as well as customers. Nevertheless, there are problems that degrade the profitability of the Internet: closed markets that cannot use each other's services; incompatible applications and frameworks that cannot interoperate or built upon each other; difficulties in exchanging business data. Web Services is a new paradigm for e-business that is expected to change the way business applications are developed and interoperate. A Web Service is a self-describing, self-contained, modular application accessible over the web. It exposes an XML interface, it is registered and can be located through a Web Service registry. Finally, it communicates with other services using XML messages over standard Web protocols. This paper presents the Web Service model and gives an overview of existing standards. It then sketches the Web Service life-cycle, discusses related technical challenges and how they are addressed by current standards, commercial products and research efforts. Finally it gives some concluding remarks regarding the state of the art of Web Services.     

The timed-token protocol for real-time communications

The timed-token protocol is a token-passing protocol in which each node receives a guaranteed share of the network bandwidth. Partly because of this property, the timed-token protocol has been incorporated into a number of network standards, including the IEEE 802.4 token bus, the Fiber Distributed Data Interface (FDDI), and the Survivable Adaptable Fiber Optic Embedded Network (Safenet). Networks based on these standards are becoming increasingly popular in new generation real-time systems. In particular, the IEEE 802.4 standard is included in the Manufacturing Automation Protocol (MAP), which has been widely used in computer-integrated manufacturing and industrial applications. Meeting message deadlines requires proper control of medium access. In the timed-token protocol, access to the communication medium is controlled by a token that is passed among the nodes in a circular fashion. Messages are segregated into two separate classes: synchronous and asynchronous. Synchronous messages, used for real-time communication, can have deadline constraints and thus are given a guaranteed share of the network bandwidth. The authors focus on meeting the deadlines of synchronous messages     

Toward practical guideline for design of image compression algorithms for biomedical applications

Improvements in medicine and healthcare are accelerating. Information generation, sharing, and expert analysis, play a great role in improving medical sciences. Big data produced by medical procedures in hospitals, laboratories, and research centers needs storage and transmission. Data compression is a critical tool that reduces the burden of storage and transmission. Medical images, in particular, require special consideration in terms of storage and transmissions. Unlike many other types of big data, medical images require lossless storage. Special purpose compression algorithms and codecs could compress variety of such images with superior performance compared to the general purpose lossless algorithms. For the medical images, many lossless algorithms have been proposed so far. A compression algorithm comprises of different stages. Before designing a special purpose compression method we need to know how much each stage contributes to the overall compression performance so we could accordingly invest time and effort in designing different stages. In order to compare and evaluate these multi-stage compression techniques and to design more efficient compression methods for big data applications, in this paper the effectiveness of each of these compression stages on the total performance of the algorithm is analyzed.     

A Schematic Entry Drawing Capability in a Linearised Hypermedia System

This paper describes a linearised hypermedia system, called the Book Emulator, that generally supports the capture of diagrammatic specifications such as SSADM and electronic circuit diagrams, and the capture of mathematical notations such as Z. Since the Book Emulator can be closely coupled to applications, it can be used as the user-interface to that application. Doing so automatically provides a conferencing mechanism on behalf of applications and a mechanism for recording the engineering analyses performed by the application. It is argued that this is the next and higher step in the trend to separate the user-interface from the application. The schematic entry mechanism has been designed to minimise the user's physical and mental effort so that the user may concentrate on drawing strategy. This is achieved by minimising the number of selections (steps) required to reach an atomic goal, and by refraining from hiding functionality in menus. The paper concludes with an indication of how the generalised schematic capture mechanism might be exploited in systems that allow end- users to organise and specify their information requirements.     

Innovation and evolution in integrated web application testing with TTCN-3

Over the last 10 years there has been continuous innovation and evolution in the technology of web applications. While originally designed as a telecom testing platform, TTCN-3 has proven to be a flexible and powerful platform for web application testing throughout this period. Major challenges to testing have been integration with unit test frameworks, service-oriented architecture, rich client interfaces, and security vulnerabilities. Through careful analysis and practical experience in industrial projects we have developed mechanisms to address each of these aspects of web application testing in TCN-3. These mechanisms are summarized here with examples drawn from our industrial experience to show how TTCN-3 provides significant advantages for testing web applications in comparison to other tools typically used in industry. We also present a significant extension to the model architecture for TTCN-3 which greatly facilitates web application testing that has been implemented by a major vendor and is now under consideration by the ETSI standards committee.     

一种采用带外虚拟化技术的网络存储系统

介绍一种基于带外虚拟化技术的网络存储系统,简称BW-VSDS,它具有以下特点:(1)采用两级带外虚拟化数据管理模型以充分发挥单个存储节点的I/O能力并释放存储网络的承载能力;(2)采用分布式数据存储管理协议以协同多个存储节点有效实现高级数据存储语义;(3)支持多种数据传输协议以适用于不同的应用环境.目前该系统已应用于视频监控、信息处理和企业办公等多个领域.     

面向高性能计算机的海量数据处理平台实现与评测

高性能计算机主要应用于传统的科学计算领域,而在云计算时代,数据密集型应用成为一大类新型应用,已经变得越来越重要.主要探索如何在高性能计算机上高效地进行海量数据处理,使高性能计算机在进行科学计算的同时,能够非常好地支持数据密集型应用,拓展高性能计算机的应用领域.分析了高性能计算机上MapReduce模型实现和部署的可行性之后,在高性能计算环境中进行了实验.实验结果表明,存储系统的并行I/O能力不能充分发挥,是造成系统无法高效运行的主要瓶颈.而导致这个性能瓶颈的原因,是高并发带来的对集群文件系统资源的竞争和冲突.最后,提出了几种解决集群文件系统资源冲突的方案,这是今后的研究方向.     

Emerging standards for component software

Component software benefits include reusability and interoperability, among others. What are the similarities and differences between the competing standards for this new technology, and how will they interoperate? Object-oriented technology is steadily gaining acceptance for commercial and custom application development through programming languages such as C++ and Smalltalk, object oriented CASE tools, databases, and operating systems such as Next Computer's NextStep. Two emerging technologies, called compound documents and component software, will likely accelerate the spread of objectoriented concepts across system-level services, development tools, and application-level behaviours. Tied closely to the popular client/server architecture for distributed computing, compound documents and component software define object-based models that facilitate interactions between independent programs. These new approaches promise to simplify the design and implementation of complex software applications and, equally important, simplify human-computer interactive work models for application end users. Following unfortunate tradition, major software vendors have developed competing standards to support and drive compound document and component software technologies. These incompatible standards specify distinct object models, data storage models, and application interaction protocols. The incompatibilities have generated confusion in the market, as independent software vendors, system integrators, in-house developers, and end users struggle to sort out the standards' relative merits, weaknesses, and chances for commercial success. Let's take a look now at the general technical concepts underlying compound documents and component software. Then we examine the OpenDoc, OLE 2, COM, and CORBA standards being proposed for these two technologies. Finally, we'll review the work being done to extend the standards and to achieve interoperability across them     

无线传感器网络中一种能量有效的数据存储方法

如何有效地对传感器在过去历史时间段内采集的大量感知数据进行存储,以备将来的信息查询和数据分析已经成为无线传感器网络应用面临的一个难题.介绍了一种基于树型路由的分布式数据存储方法,通过采用动态规划方法选择存储节点,使存储节点能量均衡和所有节点能耗之和最小,从而达到整个无线传感器网络能量有效.仿真实验结果表明,这种数据存储方法能够获得较好的能量均衡和总能耗较小,从而有效地延长整个无线传感器网络的生命周期.     

A grid-based approach for enterprise-scale data mining

We describe a grid-based approach for enterprise-scale data mining, which is based on leveraging parallel database technology for data storage, and on-demand compute servers for parallelism in the statistical computations. This approach is targeted towards the use of data mining in highly-automated vertical business applications, where the data is stored on one or more relational database systems, and an independent set of high-performance compute servers or a network of low-cost, commodity processors is used to improve the application performance and overall workload management. The goal of this paper is to describe an algorithmic decomposition of data mining kernels between the data storage and compute grids, which makes it possible to exploit the parallelism on the respective grids in a simple way, while minimizing the data transfer between these grids. This approach is compatible with existing standards for data mining task specification and results reporting, so that larger applications using these data mining algorithms do not have to be modified to benefit from this grid-based approach.     

Hardware–compiler co-design for adjustable data power savings

To efficiently accommodate standards changes and algorithmic improvements, functional reconfigurability is increasingly desired for media processing. Such adaptability, however, generally comes at significant power cost. This work suggests that another dimension of adaptation can be beneficial – power adaptation. Through a unique compiler–hardware approach, we (1) demonstrate an extension to the state-of-the-art in data analyzability, yielding better control over scratchpad data management, and (2) combine this knowledge with an SRAM having variable latency and access properties, yielding adjustable power savings. Building upon the compiler techniques presented by [1], we evaluate the severity of the current on-chip storage power problem and detail how SRAM structures can be built to enable data power savings for media applications. We show how the implemented compiler techniques can be applied to other problems in the embedded/media processing domain, and present net data power savings results for a suite of media and telecommunication applications, including MPEG-2, MPEG-4, H.263, and JPEG-2000.     

Toward a synergy between P2P and grids

Peer-to-peer (P2P) networks and grids are distributed computing models that enable decentralized collaboration by integrating computers into networks in which each can consume and offer services. P2P is a class of self-organizing systems or applications that takes advantage of distributed resources storage, processing, information, and human presence available at the Internet's edges. A grid is a geographically distributed computation platform comprising a set of heterogeneous machines that users can access through a single interface. Both are hot research topics because they offer promising paradigms for developing efficient distributed systems and applications. Unlike the classic client-server model, in which roles are well separated, P2P and grid networks can assign each node a client or server role according to the operations they are to perform on the network - even if some nodes act more as server than as client in current implementations. In spite of current practices and thoughts, the grid and P2P models share several features and have more in common than we perhaps generally recognize. It is time to consider how to integrate these two models. A synergy between the two research communities, and the two computing models, could start with identifying the similarities and differences between them.     

Controlling NUMA effects in embedded manycore applications with lightweight nested parallelism support

Embedded manycore architectures are often organized as fabrics of tightly-coupled shared memory clusters. A hierarchical interconnection system is used with a crossbar-like medium inside each cluster and a network-on-chip (NoC) at the global level which make memory operations nonuniform (NUMA). Due to NUMA, regular applications typically employed in the embedded domain (e.g., image processing, computer vision, etc.) ultimately behave as irregular workloads if a flat memory system is assumed at the program level. Nested parallelism represents a powerful programming abstraction for these architectures, provided that (i) streamlined middleware support is available, whose overhead does not dominate the run-time of fine-grained applications; (ii) a mechanism to control thread binding at the cluster-level is supported. We present a lightweight runtime layer for nested parallelism on cluster-based embedded manycores, integrating our primitives in the OpenMP runtime system, and implementing a new directive to control NUMA-aware nested parallelism mapping. We explore on a set of real application use cases how NUMA makes regular parallel workloads behave as irregular, and how our approach allows to control such effects and achieve up to 28 × speedup versus flat parallelism.