面向物联网的基于智能合约的认证和授权方案

由于存在单点失效、规模受限等问题,传统中心化的解决方案很难满足物联网的安全需求。针对这种情况,提出一个面向IoT的基于智能合约的访问控制方案。通过引用IoT智能网关作为IoT设备的中心管理节点和公有区块链的全能节点,采用中心化与去中心化相结合、私有区块链和公有区块相结合、本地局部存储和外部公共存储相结合的方法加以实现。该方案实现IoT设备和IoT智能网关的相互认证,并实现用户对IoT设备中资源及存储在数据库中的数据的授权访问,具有去中心化、分布式优点,满足了规模性和安全性要求。     

物联网应用中访问控制智能合约的形式化验证

蓝牙、WiFi等网络技术的进步推动物联网（IoT）的发展,然而IoT在方便了人们生活的同时也存在严重的安全隐患。若无安全的访问控制,非法接入IoT的访问可能给用户带来各方面的损失。传统的访问控制方法需要一个可信任的中心节点,不适合节点分散的IoT环境。区块链及智能合约的出现为IoT应用的访问控制提供了更有效的解决方案,但用一般测试方法难以保证实现IoT应用的访问控制智能合约的正确性。针对这个问题,提出一种利用模型检测工具Verds对访问控制智能合约进行形式化验证从而保障合约正确性的方法。该方法利用状态迁移系统定义Solidity智能合约的语义,应用计算树逻辑（CTL）公式描述所要验证的性质,并对智能合约交互及用户行为进行建模,从而形成Verds的输入模型及所要验证性质,然后利用Verds验证待测性质的正确性。方法核心是Solidity合约子集到Verds输入模型的转换。对两个IoT资源访问控制智能合约的实验结果表明,该方法可以对访问控制合约的典型场景及期望性质进行验证,提升了智能合约的可靠性。     

基于区块链的多维度物联网健康数据服务框架

为解决物联网上医疗健康数据的隐私性和安全性等问题，提出一种基于区块链的多维度物联网健康数据服务框架。在物联网中引入(Elliptic Curve Qu-Vanstone, ECQV)隐式证书，通过分布式账本来验证隐式证书的有效性；使用该证书来实现IoT、多接入边缘计算(Multi-Access Edge Computing, MEC)数据隐私和安全性；使用区块链的智能合约来处理与证书相关的操作，开发基于智能合约的威胁评分机制来自动撤销证书；使用MEC进一步将存储卸载功能附加到区块链上，以确保将大量已连接的设备连接到云的可扩展性。该文的框架特征优于现有其他物联网框架。     

物联网和区块链在智能工厂中的应用

"工业4.0"聚焦于智能工厂和智能生产,各国都在积极探索实践智能工厂。目前,基于物联网的智能工厂存在传感器端数据污染、传感器节点之间协同困难、传感器数据的传输层和应用层安全漏洞、物联网设备信息和位置信息泄露、物联网业务系统的多元异构等问题。文章提出了一个基于物联网和区块链智能工厂运行平台,利用区块链的分布式、可追溯、数据共享的特性及共识机制和智能合约,且通过在汽车行业应用进行分析,展现出区块链技术在智能工厂的产品全生命周期中实时传输、数据驱动、信息交互应用的潜力,以及降低管理风险和成本的优势。     

智能合约安全综述

区块链为构建社会价值传递和信任机制提供了一种新的技术。区块链的快速发展促进了智能合约与人工智能、大数据、物联网等技术的深入融合,其安全性受到重点关注。近几年,区块链与智能合约安全研究取得了较大进展,基于区块链智能合约,对智能合约的运行机制、链上安全和链外安全的最新相关研究成果进行归类、分析、比较、总结和讨论,并展望了智能合约安全性的研究方向和趋势。     

基于区块链的智能合约技术与应用综述

随着以比特币为代表的区块链技术的蓬勃发展,区块链技术已经开始逐步超越可编程货币时代而进入智能合约时代.智能合约(smart contract)是一种由事件驱动的、具有状态的代码合约和算法合同,随着区块链技术的深入发展而受到广泛关注和研究.智能合约利用协议和用户接口完成合约过程的所有步骤,允许用户在区块链上实现个性化的代码逻辑.基于区块链的智能合约技术具有去中心化、自治化、可观察、可验证、可信息共享等特点,可以有效构建可编程金融和可编程社会,广泛应用于数字支付、金融资产处置、多重签名合约、云计算、物联网、共享经济等多个领域.首先阐述了智能合约技术的基本概念、全生命周期、基本分类、基本架构、关键技术、发展现状以及智能合约的主要技术平台;然后探讨了智能合约技术的应用场景以及发展中所存在的问题;最后,基于智能合约的理论知识,搭建了以太坊实验环境并开发了一个众筹智能合约系统,旨在为基于区块链的智能合约技术的研究与发展提供参考与借鉴.     

基于智能合约构建可信物联网安全模型

物联网系统错综复杂,数据会在整个传输过程中经过不同的载体,其存在的隐私安全和漏洞问题也随着暴露出来。为解决传统防护技术的不足,保证物联网信息安全,本文旨在研究基于区块链技术的物联网信息安全技术,利用区块链技术在物联网网关之间建立安全的通信通道,通过在物联网网关中设置检查点来管理智能合约,与传输的所有数据链及其支链构建Merkle树,根据Merkle树根哈希值验证数据是否被篡改,提高物联网数据传输的安全性。     

基于区块链的智能门禁可信监控系统

为解决传统智能门禁中用户生物特征易被盗取、监控数据易被伪造等问题,提出一种基于以太坊区块链的智能门禁监控系统。利用智能合约将用户身份信息与监控数据写入区块链,配合硬件设计的身份识别与入侵检测,实现链上链下的协同工作,有效避免集中管理造成的数据篡改以及暴力窃取链下用户信息等潜在问题。根据区块链不可篡改的特性,利用代理合约实现智能合约的升级,达到提升系统扩展性的目的。实验结果表明,在保证身份识别以及监控数据可信的基础上,系统性能可以达到实际应用所需效果。     

面向数据保护的区块链物联网边缘卸载策略

物联网（IoT）设备的广泛应用带来了数据安全性和完整性的挑战。针对这一问题,研究提出了一种区块链物联网边缘卸载策略,专注于数据保护。该策略通过将IoT设备数据上传至区块链,利用其不可窜改性和可追溯性来保障数据安全。鉴于区块链的工作量证明（PoW）共识算法在数据验证和区块添加方面的高计算资源需求,该策略采用边缘计算技术,将PoW共识过程卸载至边缘服务器执行。进一步地,设计并实现了一个多目标边缘卸载算法（multi-object edge offloading algorithm,MEOA）,以寻找最优卸载策略,动态调整PoW共识难度,实现系统安全性与运行效率的平衡。仿真实验结果显示,该策略相比其他卸载策略,在提高IoT设备数据上链效率、降低时间和能耗成本方面表现优异,同时确保了数据安全性和完整性。     

基于区块链的物联网认证机制综述

随着物联网(Internet of Things, IoT)技术的高速发展,各类智能设备数量激增,身份认证成为保障IoT安全的首要需求.区块链作为一种分布式账本技术,提供了去信任的协作环境和安全的数据管理平台,使用区块链技术驱动IoT认证成为学术界和工业界关注的热点.基于云计算和云边协同两种架构分析IoT身份认证机制设计的主要需求,总结区块链技术应用于IoT场景面临的挑战;梳理现有IoT身份认证机制的工作,并将其归结为基于密钥的认证、基于证书的认证和基于身份的认证;分析应用区块链技术的IoT认证工作,并根据认证对象和附加属性对相关文献进行归纳和总结.从形式化和非形式化两个方向总结基于区块链的IoT认证机制的安全性分析方法.最后展望了未来研究方向.     

Only connect: teaching, technology and telesis

Abstract This paper describes an approach to the design of interactive multimedia materials being developed in a European Community project. The developmental process is seen as a dialogue between technologists and teachers. This dialogue is often problematic because of the differences in training, experience and culture between them. Conditions needed for fruitful dialogue are described and the generic model for learning design used in the project is explained.     

European Community policy and the market

Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven.     

一种自适应子融合集成多分类器方法

融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。     

Avoiding semantic and temporal gaps in developing software intensive systems

Development of software intensive systems (systems) in practice involves a series of self-contained phases for the lifecycle of a system. Semantic and temporal gaps, which occur among phases and among developer disciplines within and across phases, hinder the ongoing development of a system because of the interdependencies among phases and among disciplines. Such gaps are magnified among systems that are developed at different times by different development teams, which may limit reuse of artifacts of systems development and interoperability among the systems. This article discusses such gaps and a systems development process for avoiding them.     

Designing economic np control charts: A programmed simulation approach

This paper presents control charts models and the necessary simulation software for the location of economic values of the control parameters. The simulation program is written in FORTRAN, requires only 10K of main storage, and can run on most mini and micro computers. Two models are presented - one describes the process when it is operating at full capacity and the other when the process is operating under capacity. The models allow the product quality to deteriorate to a further level before an existing out-of-control state is detected, and they can also be used in situations where no prior knowledge exists of the out-of-control causes and the resulting proportion defectives.     

The development of robot art

Going through a few examples of robot artists who are recognized worldwide, we try to analyze the deepest meaning of what is called “robot art” and the related art field definition. We also try to highlight its well-marked borders, such as kinetic sculptures, kinetic art, cyber art, and cyberpunk. A brief excursion into the importance of the context, the message, and its semiotics is also provided, case by case, together with a few hints on the history of this discipline in the light of an artistic perspective. Therefore, the aim of this article is to try to summarize the main characteristics that might classify robot art as a unique and innovative discipline, and to track down some of the principles by which a robotic artifact can or cannot be considered an art piece in terms of social, cultural, and strictly artistic interest. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

Explanation and prediction: an architecture for default and abductive reasoning

Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given.     

Three Process Perspectives: Organizations, Teams, and People

This paper provides the author's personal views and perspectives on software process improvement. Starting with his first work on technology assessment in IBM over 20 years ago, Watts Humphrey describes the process improvement work he has been directly involved in. This includes the development of the early process assessment methods, the original design of the CMM, and the introduction of the Personal Software Process (PSP)^SM and Team Software Process (TSP){^SM}. In addition to describing the original motivation for this work, the author also reviews many of the problems he and his associates encountered and why they solved them the way they did. He also comments on the outstanding issues and likely directions for future work. Finally, this work has built on the experiences and contributions of many people. Mr. Humphrey only describes work that he was personally involved in and he names many of the key contributors. However, so many people have been involved in this work that a full list of the important participants would be impractical.     

基于复小波噪声方差显著修正的SAR图像去噪

提出了一种基于复小波域统计建模与噪声方差估计显著性修正相结合的合成孔径雷达(Synthetic Aperture Radar,SAR)图像斑点噪声滤波方法。该方法首先通过对数变换将乘性噪声模型转化为加性噪声模型,然后对变换后的图像进行双树复小波变换(Dualtree Complex Wavelet Transform,DCWT),并对复数小波系数的统计分布进行建模。在此先验分布的基础上,通过运用贝叶斯估计方法从含噪系数中恢复原始系数,达到滤除噪声的目的。实验结果表明该方法在去除噪声的同时保留了图像的细节信息,取得了很好的降噪效果。     

How do children do mathematics with LOGO?

Abstract  This paper considers some results of a study designed to investigate the kinds of mathematical activity undertaken by children (aged between 8 and 11) as they learned to program in LOGO. A model of learning modes is proposed, which attempts to describe the ways in which children used and acquired understanding of the programming/mathematical concepts involved. The remainder of the paper is concerned with discussing the validity and limitations of the model, and its implications for further research and curriculum development.