Efficient data compression for seismic-while-drilling applications

Seismic-while-drilling services efficiently support drilling decisions. They use the vibrations produced by the drill-bit during perforation as a downhole seismic source. The seismic signal is recorded by sensors on the surface, and it is processed in order to obtain/update an image of the subsurface around the borehole. To improve the characterization of the source, some sensors have been experimentally installed also downhole, on the drill pipes in close proximity to the bit: data logged downhole have been able to give better quality information. Currently, the main drawback of downhole equipment is the absence of a high-bit-rate telemetry system to enable real-time activities. This problem may be solved by employing either an offline solution, with limited memory capacity up to few hundreds of megabytes, or an online solution with telemetry at a very low bit-rate (few bits per second). However, following the offline approach with standard acquisition parameters, the internal storage memory would be filled up in just a few hours at high acquisition rates. On the contrary, with the online solution, only a small portion of the acquired signals (or only alarm information about potentially dangerous events) can be transmitted in real time to the surface by using conventional mud-pulse telemetry. We present a lossy data compression algorithm based on a new representation of downhole data in angle domain, which is suitable for downhole implementation and may be successfully applied to both online and offline solutions. Numerical tests based on real field data achieve compression ratios up to 112:1 without major loss of information. This allows a significant increase in downhole time acquisition and in real-time information that can be transmitted through mud-pulse telemetry.     

在线混沌聊天保密通信研究

利用离散混沌映射进行信息的加解密,设计并实现了一个网络在线文字聊天保密通信系统,它不仅提供了一个实时通信平台,而且也保证了通信的保密性。系统采用倾斜帐篷映射,通过密钥同步方案,信息被实时加密后经TCP协议传输;而且由于混沌映射具有类随机特性及初值敏感性,传输的信息很难被破译,保密性较强。     

Efficient Set Intersection with Simulation-Based Security

We consider the problem of computing the intersection of private datasets of two parties, where the datasets contain lists of elements taken from a large domain. This problem has many applications for online collaboration. In this work, we present protocols based on the use of homomorphic encryption and different hashing schemes for both the semi-honest and malicious environments. The protocol for the semi-honest environment is secure in the standard model, while the protocol for the malicious environment is secure in the random oracle model. Our protocols obtain linear communication and computation overhead. We further implement different variants of our semi-honest protocol. Our experiments show that the asymptotic overhead of the protocol is affected by different constants. (In particular, the degree of the polynomials evaluated by the protocol matters less than the number of polynomials that are evaluated.) As a result, the protocol variant with the best asymptotic overhead is not necessarily preferable for inputs of reasonable size.     

基于XML网上书店系统的设计

XML是新一代网络数据表示、传递和交换的标准,是Internet环境中跨平台的、依赖于内容的技术。XML的新特性改变了人们在网络的交换方式,加速了电子商务的发展。网上书店系统体系结构采用B/S结构,MSVS2005作为B/S结构应用程序的开发工具。在开发中采用基于XML技术及MSSQLServer2005数据库技术,实现了用户登录注册、图书信息浏览、图书搜索、购物车、书籍管理、结账、生成订单等主要功能,使系统具有方便快捷、界面友好、可移植等特点。     

An RNS Architecture for Quasi-Chaotic Oscillators

Wideband chaotic carrier is a promising solution for wideband communication, since it overcomes the disadvantages of both narrowband and spread-spectrum communication. It is particularly suited to realize information encryption for secure communication. Chaotic signals can be generated by using discrete-time non-linear dynamical circuits, since they can exhibit a quasi-chaotic (QC) behavior. A particular implementation of QC digital filters can be based on finite precision arithmetic and, in particular, on residue number system (RNS) circuits, which possess very attractive features with regard to their VLSI implementation. In the present paper, we propose an RNS architecture that can be used in connection with secure communication. Each RNS channel consists of a QC oscillator, having its coefficients belonging to a Galois field defined by a prime modulus. In particular, the QC behavior is ensured by well-known properties of primitive polynomials in this field, which generate the characteristic feedback of the oscillator. We demonstrate in the paper that the proposed RNS architecture yields a cost-effective VLSI implementation, which favorably compares with respect to other secure communication approaches proposed in the technical literature. We obtain encouraging results both in terms of confidentiality of the encrypted information and of throughput rate for real-time applications. Moreover, we propose an extended architecture suited to the protection of the secure communication system against transmission errors, by using the self-correcting ability of Redundant RNS (RRNS).     

LiAS: a reflexive navigation architecture for an intelligent mobilerobot system

In this paper, a complete hierarchical navigation architecture fur applications in real industrial factory environments is presented. An offline global geometrical planner uses a rough CAD-model of the working environment to plan consecutive via-points which the robot must follow. The navigation between the via-points is performed by a two-level online navigation algorithm. It consists of an online planning module combined with a low-level fuzzy logic avoidance behavior which enables the robot to move to the next goal by only specifying its coordinates in even completely a priori unknown and unstructured factory environments. The system includes a docking motion, based on a dynamic guidance technique. A perception fusion module combines information of three different sensors for accurate modeling of the world. The presented navigation method was tested with the mobile robot Leuven Intelligent Autonomous System (LiAS) and it proved to be useful in real world applications     

Optimal Dynamic Voltage Scaling in Energy-Limited Nonpreemptive Systems with Real-Time Constraints

Dynamic voltage scaling is used in energy-limited systems as a means of conserving energy and prolonging their life. We consider a setting in which the tasks performed by such a system are nonpreemptive and aperiodic. Our objective is to control the processing rate over different tasks so as to minimize energy subject to hard real-time processing constraints. Under any given task scheduling policy, we prove that the optimal solution to the offline version of the problem can be efficiently obtained by exploiting the structure of optimal sample paths, leading to a new dynamic voltage scaling algorithm termed the critical task decomposition algorithm (CTDA). The efficiency of the algorithm rests on the existence of a set of critical tasks that decompose the optimal sample path into decoupled segments within which optimal processing times are easily determined. The algorithm is readily extended to an online version of the problem as well. Its worst-case complexity of both offline and online problems is O(N²)     

基于主成分分析的实时全网络异常检测方法

网络性能异常检测对于促进网络健康发展具有重要意义。针对目前全网性能异常检测大多通过离线检测,无法提供良好的实时在线检测性能的问题。文中采用主成分分析方法建立异常检测模型,结合历史性能数据和近期网络性能波动状况去适应性调整网络异常判断阈值,实现了异常检测的实时在线化,并在NFV网络上进行数据采集。实验结果表明,与被广泛采用的离线检测方法比较,该方法在检测的误报率上减少了5%8%,对于网络运行商而言具有较大的使用价值。     

WAVE协议栈下基于高斯混合模型的无线定位研究

无线定位是车联网中各应用的基础,对实时性和精度要求更高。基于此,本文提出了一个在WAVE系统下基于混合高斯模型的位置指纹定位算法。该算法由离线训练和在线定位两部分组成,采用GMM对离线训练阶段的指纹数据库进行聚类建模处理,并在定位阶段对结果采用多点均值方法,不仅降到了系统定位误差,也减少了定位阶段的运算量,提高了定位的实时性。实验结果表明,该算法有较好的定位精度和实时性,为WAVE环境下的快速定位进一步研究提供有效参考价值。     

量子保密通信发展趋势与对策探讨

目前,国内外在量子保密通信系统实验和应用研究方面取得了很大进展,虽然人们对量子系统的实用性存在较大的争论,但相关研究已经进入了工程实现的关键时期。量子保密通信在窃听检测、身份识别和在线密钥共享等方面具有得天独厚的优势,必将对保密通信领域产生革命性的影响。论文对量子保密通信的技术现状、技术原理和特色进行了介绍,对量子保密通信发展趋势、应用前景和应对策略等进行了分析和探讨。     

基于Docker容器技术的Linux在线实验环境设计

基于Docker容器的虚拟技术在云计算、大数据环境中被大规模的使用,针对Linux操作系统实验环境使用受限的问题,设计了基于Docker容器技术的在线实验环境,描述了实验环境构建的大致过程,对服务器端Docker容器的创建方法进行了分类分析和服务器压力测试,结果表明,所设计的Linux在线实验环境能够满足线上及线下教学...     

Fog-Sec: Secure end-to-end communication in fog-enabled IoT network using permissioned blockchain system

The technological integration of the Internet of Things (IoT)-Cloud paradigm has enabled intelligent linkages of things, data, processes, and people for efficient decision making without human intervention. However, it poses various challenges for IoT networks that cannot handle large amounts of operation technology (OT) data due to physical storage shortages, excessive latency, higher transfer costs, a lack of context awareness, impractical resiliency, and so on. As a result, the fog network emerged as a new computing model for providing computing capacity closer to IoT edge devices. The IoT-Fog-Cloud network, on the other hand, is more vulnerable to multiple security flaws, such as missing key management problems, inappropriate access control, inadequate software update mechanism, insecure configuration files and default passwords, missing communication security, and secure key exchange algorithms over unsecured channels. Therefore, these networks cannot make good security decisions, which are significantly easier to hack than to defend the fog-enabled IoT environment. This paper proposes the cooperative flow for securing edge devices in fog-enabled IoT networks using a permissioned blockchain system (pBCS). The proposed fog-enabled IoT network provides efficient security solutions for key management issues, communication security, and secure key exchange mechanism using a blockchain system. To secure the fog-based IoT network, we proposed a mechanism for identification and authentication among fog, gateway, and edge nodes that should register with the blockchain network. The fog nodes maintain the blockchain system and hold a shared smart contract for validating edge devices. The participating fog nodes serve as validators and maintain a distributed ledger/blockchain to authenticate and validate the request of the edge nodes. The network services can only be accessed by nodes that have been authenticated against the blockchain system. We implemented the proposed pBCS network using the private Ethereum 2.0 that enables secure device-to-device communication and demonstrated performance metrics such as throughput, transaction delay, block creation response time, communication, and computation overhead using state-of-the-art techniques. Finally, we conducted a security analysis of the communication network to protect the IoT edge devices from unauthorized malicious nodes without data loss.     

Designing the Next Generation of Real-Time Control, Communication, and Computations for Large Power Systems

The power grid is not only a network interconnecting generators and loads through a transmission and distribution system, but is overlaid with a communication and control system that enables economic and secure operation. This multilayered infrastructure has evolved over many decades utilizing new technologies as they have appeared. This evolution has been slow and incremental, as the operation of the power system consisting of vertically integrated utilities has, until recently, changed very little. The monitoring of the grid is still done by a hierarchical design with polling for data at scanning rates in seconds that reflects the conceptual design of the 1960s. This design was adequate for vertically integrated utilities with limited feedback and wide-area controls; however, the thesis of this paper is that the changing environment, in both policy and technology, requires a new look at the operation of the power grid and a complete redesign of the control, communication and computation infrastructure. We provide several example novel control and communication regimes for such a new infrastructure.     

A blockchain-enabled wiki framework based on participatory design

The 5G mobile Internet facilitates contents generation for online communities and platforms through human-to-human collaboration. Wikipedia, a well-known online community, uses wiki technology to build an encyclopedia through collective intelligence and collaboration. Mainstream wiki systems adopt a centralized implementation, and while existing studies have optimized the efficiency of the wiki systems' centralized implementation, these systems still suffer from a lot of problems, for example, opacity and distrust. Over the years, blockchain has brought a flurry of fervour and decentralization to the system architecture, meanwhile giving users a sense of trust and participation. Thus, an innovative blockchain-enabled wiki framework called DecWiki is proposed to build one transparent, truthful, collaborative and autonomous encyclopedia. After several participatory design iterations, we present DecWiki's detailed architecture and its implementation in the form of a smart contract and use the interplanetary file system to complement the big data storage. Meanwhile, we use the trusted execution environment to secure sensitive information in the wireless scenario. Finally, the system overhead and the acceptance of the prototype are evaluated. Extensive experiments present its significant performance.     

基于同态加密的智能电表数据聚合方案

针对多个智能电表实时采集数据聚合上传过程中所存在的用户隐私泄露和计算效率不高的问题,提出了一个基于同态加密的智能电表数据聚合方案。该聚合方案使得多个智能电表数据能够聚合传输至电力系统,而电力系统却无法得到单个智能电表的用电数据。仿真结果表明,该方案在智能电表侧和聚合器侧均可有效降低计算成本和通信成本。     

基于AR技术的实时互动体验电商系统

电商已经不仅仅满足于线上的商品交易,越来越多地开始关注于线下用户体验的改善.本文以虚拟试鞋为切入口,借助于Kinect硬件设备和3d Max、unity3d软件平台,提出并搭建了基于AR增强现实技术的实时互动体验电商系统.本文对该系统的关键技术进行阐述,包括三维模型的跟踪定位、手势交互和RGB-D抠像.该系统综合应用三维场景虚拟化、三维互动识别以及增强现实融合等技术,硬件成本和算法复杂度低,操作简单,适用于新型电商利用AR技术对品牌进行线上展示和线下用户体验.     

High-level software synthesis for the design of communicationsystems

A synthesis environment that targets software programmable architectures such as digital signal processors (DSPs) is presented. These processors are well suited for implementation of real-time signal processing systems with medium throughput requirements. Techniques that tightly couple the synthesis environment to an existing communication system simulator are also presented. This enables a seamless transition between the simulation and implementation design level of communication systems. Special focus is on optimization techniques for mapping data flow oriented block diagrams onto DSPs. The combination of different mapping and optimization strategies allows comfortable synthesis of real-time code that is highly adapted to application-specific needs imposed by constraints on memory space, sampling rate, or latency. Thus, tradeoff analysis is supported by efficient interactive or automatic exploration of the design space. All presented concepts are illustrated by the design of a phase synchronizer with automatic gain control on a floating-point DSP     

数据新鲜度驱动的协作式无人机联邦学习智能决策优化研究

联邦学习是6G关键技术之一,其可以在保护数据隐私的前提下,利用跨设备的数据训练一个可用且安全的共享模型。然而,大部分终端设备由于处理能力有限,无法支持复杂的机器学习模型训练过程。在异构网络融合环境下移动边缘计算(MEC)框架中,多个无人机(UAVs)作为空中边缘服务器以协作的方式灵活地在目标区域内移动,并且及时收集新鲜数据进行联邦学习本地训练以确保数据学习的实时性。该文综合考虑数据新鲜程度、通信代价和模型质量等多个因素,对无人机飞行轨迹、与终端设备的通信决策以及无人机之间的协同工作方式进行综合优化。进一步,该文使用基于优先级的可分解多智能体深度强化学习算法解决多无人机联邦学习的连续在线决策问题,以实现高效的协作和控制。通过采用多个真实数据集进行仿真实验,仿真结果验证了所提出的算法在不同的数据分布以及快速变化的动态环境下都能取得优越的性能。     

Politics As Usual,or Politics Unusual? Position Taking and Dialogue on Campaign Websites in the 2002 U.S. Elections

Many consider the World Wide Web to be nothing more than an additional medium alongside others in which established patterns of political behavior and information flows are played out anew; others contend that the special characteristics of the Web hold the potential to produce fundamentally different patterns of political behavior than those found offline. This article analyzes the occurrence of position taking and issue dialogue on campaign websites associated with a random sample of 200 races from the U.S. 2002 election cycle. Though this study found some similarities between online and offline campaigning, it also identified ways in which the individual messages and overall political information environment created by candidates and available to voters through the Web in 2002 did not conform to the usual patterns found in the offline world of print and broadcast communication.