Mobile computing and ubiquitous networking: concepts, technologies and challenges

With the rapidly increasing penetration of laptop computers, which are primarily used by mobile users to access Internet services, support of Internet services in a mobile environment become an increasing need. The opportunities emerging from these technologies give rise to new paradigms such as mobile computing and ubiquitous networking. However, there are numerous challenges such as reliability and quality of service, infrastructure costs, energy efficiency of mobile devices, among others. This paper analyzes concepts, technologies and challenges related to these paradigms. The major challenges include mobility, disconnection and scale, new information medium and new resource limitations. As a fundamental characteristics of mobile environments, the user can see the same computing environment regardless of his or her current location. The most exciting promises of mobile computing and ubiquitous networking stay an entire new class of applications and potential new massive markets combining personal computing and consumer electronics.     

Wireless optical CDMA LAN: digital design concepts

In this paper we study and present an in-depth analysis on the operability and the viability of a typical wireless optical CDMA (OCDMA) local area network. Three receiver structures for OCDMA systems, using optical orthogonal codes (OOC) with minimum auto and cross-correlations as signature sequence, namely, correlation, correlation with hard-limiter, and chip-level detection are studied and proposed for such a network. For the synchronization circuit design the performance of two algorithms for OOC based OCDMA networks, namely, simple serial-search and multiple-shift in the context of wireless OCDMA LAN are studied. Furthermore, we study a synchronization method based on matched filtering and show that it presents a much better performance in our wireless OCDMA system. The effect of sampling rate and its performance on tracking circuit is analyzed. Bit-error-rate (BER) analysis is performed by photon counting methodology. Multi-user interference (MUI), ambient light, and photodetector dark current are considered in our analysis. Our analysis strongly indicates the viability and practicality of such systems in certain important wireless optical communications systems.     

From application service provision to service-oriented computing: A study of the IT outsourcing evolution

IT outsourcing is not a new concept. Originating from the early 60’s in the form of time sharing, IT outsourcing has evolved to the application service provision (ASP) model, in the late 90’s to pure services in the beginning of the century. Services, and their major representative web services, are actually the next phase of the movement toward Internet-based componentized software, known in the not so distant past as ASP. As the continuous expansion of the Internet and its relating technologies creates new marketing opportunities, traditional monolithic architectures are giving way to service-oriented computing (SOC), the architecture that enables service provision. SOC permits the utilization of large systems which are comprised of self-containing building blocks: services. Services may be made public, searched, reused and combined to form complex business processes while in the same time retaining a significant level of flexibility. Services and SOC have emerged as a response to a fundamental shift in enterprise business culture that started at the late 90’s. Although they are promising as an IT outsourcing enabler, many issues need to be dealt with before they can be considered suitable for wide adoption. These issues are of technological, business, economic and cultural nature and they were also faced by ASPs in the past. It is worth revisiting the successes and failures of the ASP model in order to get a better understanding of the evolving IT outsourcing industry. In this work, we describe the evolution of service provision from its initial form as software application, through the application service provision era and towards the new trend of web services.     

Multilevel codes: theoretical concepts and practical design rules

This paper deals with 2^l-ary transmission using multilevel coding (MLC) and multistage decoding (MSD). The known result that MLC and MSD suffice to approach capacity if the rates at each level are appropriately chosen is reviewed. Using multiuser information theory, it is shown that there is a large space of rate combinations such that MLC and full maximum-likelihood decoding (MLD) can approach capacity. It is noted that multilevel codes designed according to the traditional balanced distance rule tend to fall in the latter category and, therefore, require the huge complexity of MLD. The capacity rule, the balanced distances rules, and two other rules based on the random coding exponent and cutoff rate are compared and contrasted for practical design. Simulation results using multilevel binary turbo codes show that capacity can in fact be closely approached at high bandwidth efficiencies. Moreover, topics relevant in practical applications such as signal set labeling, dimensionality of the constituent constellation, and hard-decision decoding are emphasized. Bit interleaved coded modulation, proposed by Caire et al. (see ibid., vol.44, p.927-46, 1998), is reviewed in the context of MLC. Finally, the combination of signal shaping and coding is discussed. Significant shaping gains are achievable in practice only if these design rules are taken into account     

Advanced concepts in electric vehicle design

In 1994, the Eco-Vehicle Project was begun to develop an electric vehicle (EV) using a ground-up design approach that incorporates unique designs specific to an EV. The Eco-Vehicle will be a high-performance, but ultrasmall, battery-powered vehicle. New designs for the Eco-Vehicle include an in-wheel motor drive system, a hollow load floor which will house the batteries, and a new battery management system. The Eco-Vehicle may also utilize other advanced concepts suitable especially for EVs, including solar panels for battery charging and intelligent crash avoidance and guidance systems     

从亚波长光栅到超构光栅:原理、设计及应用

随着纳米光子学的发展,光学结构如光学微腔、波导结构、光子晶体、亚波长光栅、超构表面等能够在微纳尺度实现对光的传输与调控,推动了光学集成化的发展。亚波长光栅由于其结构简单、成本低廉等特点得到了科学家们广泛的研究,应用在各种光学器件,逐渐形成了光栅分析模型的成熟理论体系。结合周期性结构耦合行为及超构表面中超构原子的散射调制特性,从亚波长光栅衍生出的超构光栅能够利用周期性布拉格散射提高调控光束的效率,从而避免了超构表面相位离散化带来的效率降低和能量损失。科学家们研究并设计了超构光栅,更多的物理现象及应用被探究和挖掘。文中对亚波长光栅以及超构光栅的基本理论、设计和应用进行了概述。从基本原理出发,论述了亚波长光栅和超构光栅的特性,综述了二者的理论设计及单元设计方法,并介绍了在生物传感、滤光片光谱调控和吸收薄膜等方面的应用。最后,展望了未来的发展方向。     

The Eos data and information system: concepts for design

A functional architecture for the Earth observing system (Eos) is presented and a variety of management issues are surveyed, including longevity, coordination with agencies, scientific programs, and other nations, incorporation of existing data, and the importance of effective and responsible scientific governance by the users. The author concludes that to meet its objectives, the system must facilitate the development of abstract higher-level data structures and data manipulation languages. If that occurs, the Eos data and information system will, he believes, stimulate novel and more powerful modes of thought about the information that portrays the evolution of the Earth system     

The design of DNA self-assembled computing circuitry

We present a design methodology for a nanoscale self-assembling fabrication process that uses the specificity of DNA hybridization to guide the formation of electrical circuitry. Custom design software allows us to specify the function of a structure in a way similar to that used by VLSI circuit designers. In an analogous manner to generating masks for a photolithographic process, our software generates an assembly procedure including DNA sequence allocation. We have found that the number of unique DNA sequences needed to assemble a structure scales with its surface area. Using a simple face-serial assembly order we can specify an unambiguous assembly sequence for a structure of any size with only 15 unique DNA sequences.     

互联网的设计理念与网络5.0技术

互联网发展了50年,其设计理念从未改变,业务网完全采用OTT方式,IP网至今还是“尽力而为”,制约了互联网的发展。要不断满足社会发展的需要,互联网设计理念需要变革,可行的方向是由“以应用为中心”变为“以网络为中心”。网络5.0是第5代数据网,与第4代数据网（IP网）相比,保留IP网的全部优点,填补了IP网在网络性能和能力上的不足,性能和能力上有质的进步。具体讨论了网络5.0在可扩展性、内生可信安全、确定性等多方面的关键技术。     

一种用于可信计算的RISC-V处理器设计

针对我国自主可控处理器的设计需求,文中采用开源RISC-V指令集架构设计了一种适用于可信计算的处理器。处理器内核中指令运算阶段使用5级流水线技术,并采用定向前推技术解决了数据相关问题。仿真阶段使用Modelsim仿真软件对整数指令集进行测试,经验证指令功能正确。借助FPGA开发板,以国产操作系统深度为平台,在50 MHz的时钟频率下处理器能正确运行SM3密码杂凑算法,输出256 bit的杂凑值,并与预存杂凑值进行比对,根据比对结果输出IO控制信号,完成对外部设备的主动控制及度量,达到预期目标。     

From IPTV to synchronous shared experiences challenges in design: Distributed media synchronization

Recent developments on Social TV point to an evolution from traditional IPTV services towards more social experiences. Newer applications and services have appeared wherein groups of people in different locations can watch multimedia content while synchronously communicating with each other. We name such applications as synchronous shared experiences. Realization of these shared experiences requires that users feel that they are coherently communicating with each other. This paper identifies and analyzes challenges that need to be tackled to achieve coherence: quality of service, mobility and distributed media synchronization. Furthermore, universal session handling is required to setup these sessions. We then present our solution to one of these challenges: distributed media synchronization. Our design uses the local lag mechanism over a distributed control or master-slave signaling architecture. We validate our implementation via experiments performed with one client located in Amsterdam and the other in Seoul. The experiments demonstrate a bound in play-out skew of 500 ms across these locations. Our results from user tests, presented elsewhere, show that this value is well within tolerance limits.     

DSBS: A Novel Dependable Secure Broadcast Stream over Lossy Channels

Confidential authenticated broadcast/multi cast over lossy channels is an important and challenging problem. Applications include the continuous confidential authentication of radio and TV internet broadcast/multicast data distribution by satellite and critical data broadcast in critical tasks (e.g. sensor network for military tasks). Main challenges are authenticity, confidentiality, loss-tolerance, efficiency. Asymmetric cryptography approaches have high security but are expensive in computation and communication. In this paper we propose and prototype a novel loss-tolerance mechanism for lossy channels ensuring authenticity, confidentiality, DoS resistance, efficiency and simplicity. Most applications in practice do not need ideal and perfect real-time task and a minor delay around some seconds is completely acceptable, except a few applications such as safety beacons in VANET. In many applications, such as updating code memory of MANET, delay around some minutes is acceptable, too. Hence, our aim is to provide a robust and dependable loss-tolerant secure broadcast stream at cost of delayed-verification. As an experimental implementation we prototype our proposal in a wireless sensor networks to show its efficiency.     

From the editors: collaborative computing community - leveraging single-user applications for multiuser distributed collaboration

Single-user interactive computer applications are pervasive in our work and daily lives. Commonly used single-user interactive applications include text editors such as Notepad and Emacs, word processors such as Office Word and OpenOffice Writer, spreadsheet tools such as Office Excel and OpenOffice Calculator, slide authoring and presentation tools such as Office PowerPoint and OpenOffice Impress, Web authoring tools such as FrontPage and Dreamweaver, CAD systems such as AutoCAD and Catia, and media creation tools such as Maya and 3D Studio Max. The choices for real-time collaborative applications, however, are limited. Most advanced real-time collaborative applications are research prototypes with limited functionalities and usability. The vast majority of existing commercial applications were designed for single users, and future applications' design is expected to continue to be single-user-centric.     

基于云计算混合式学习的教学设计

本文以《面向对象程序设计(c#)之switch语句》为教学案例,详细描述了一个基于课堂讲授、实训室、云平台混合式学习教学设计的实施过程,任务驱动激发学生学习兴趣,教师引导、学生自主探索实践相结合,知识传授、素质培养、能力提高融为一体,不断提高教学质量和学习效果.     

基于云计算的教学资源共享平台设计

在虚拟云计算环境下开发了一个资源共享平台RSBCC,详细介绍了它的架构、核心模块、主要功能、设计操作环境和应用。它具有良好的可扩展性,可以提高资源的共享和利用,适用于计算机科学的教学和研究过程。     

The research and design of reconfigurable computing for Block cipher

This paper describes a new specialized Reconfigurable Cryptographic for Block ciphers Architecture（RCBA）.Application-specific computation pipelines can be configured according to the characteristics of the block cipher processing in RCBA,which delivers high performance for cryptographic applications.RCBA adopts a coarse-grained reconfigurable architecture that mixes the appropriate amount of static configurations with dynamic configurations.RCBA has been implemented based on Altera’s FPGA,and representative algorithms of block cipher such as DES,Rijndael and RC6 have been mapped on RCBA architecture successfully.System performance has been analyzed,and from the analysis it is demonstrated that the RCBA architecture can achieve more flexibility and efficiency when compared with other implementations.