Privacy‐preserving authentication scheme for on‐road on‐demand refilling of pseudonym in VANET

Privacy in Vehicular Ad Hoc Networks (VANET) is fundamental because the user's safety may be threatened by the identity and the real‐time spatiotemporal data exchanged on the network. This issue is commonly addressed by the use of certified temporal pseudonyms and their updating strategies to ensure the user's unlinkability and anonymity. IEEE 1609.2 Standard specified the process of certifying pseudonym along with certificates structure. However, the communication procedure between the certifying authority and the requesting vehicle was not defined. In this paper, a new privacy‐preserving solution for pseudonym on‐road on‐demand refilling is proposed where the vehicle anonymously authenticates itself to the regional authority subsidiary of the central trusted authority to request a new pseudonyms pool. The authentication method has two phases, the first one uses anonymous tickets, and the second one is a challenge‐based authentication. The anonymous tickets are certificates that do not include the identity of the user. Instead, it contains a reference number and the certifying authority signature. The challenge authentication is identity‐less to preserve the privacy, yet it is used to prevent the misuse of tickets and the impersonation of its owner. Our proposed scheme is analyzed by the use of Burrows, Abadi and Needham (BAN) logic to demonstrate its correctness. It is also specified and checked by using the Security Protocol ANimator (SPAN) and the Automated Validation of Internet Security Protocols and Applications (AVISPA) tools. The logical demonstration proved that this privacy‐preserving authentication is assured. The SPAN and AVISPA tools illustrated that it is resilient to security attacks.     

湿法烟气脱硫控制系统方案研究

为了实现对湿法烟气脱硫控制的需求,本文提出了石灰石-石膏湿法烟气脱硫系统设计方案。主要从控制方式设计、控制系统硬件配置、I/O清单设计、自动调节系统设计、增压风机联锁保护条件的设计、重要顺控设计、重要仪表的选型和设计等方面进行阐述,以实现湿法烟气脱硫的自动化控制。     

两级优先级控制轮询系统研究

 本文基于区分业务优先级服务的应用需求,提出了两级优先级控制的轮询系统,采用门限服务和完全服务的不同服务策略方式实现了基于优先级的控制.然后,应用马尔可夫链和概率母函数的方法建立了系统模型,并精确解析了系统的平均排队队长和信息分组的平均等待时间关键特性,理论计算和仿真实验的对比分析说明了理论分析与实验的一致性,新的轮询系统实现了优先级的控制并提高了系统性能.     

A lightweight authentication scheme based on self‐updating strategy for space information network

The security of space information network (SIN) is getting more and more important now. Because of the special features of SIN (e.g., the dynamic and unstable topology, the highly exposed links, the restricted computation power, the flexible networking methods, and so on), the security protocol for SIN should have a balance between security properties and computation/storage overhead. Although a lot of security protocols have been proposed recently, few can provide overall attacks resistance power with low computation and storage cost. To solve this problem, in this paper we propose a lightweight authentication scheme for space information network. It is mainly based on the self‐updating strategy for user's temporary identity. The scheme consists of two phases, namely, the registration phase and the authentication phase. All the computing operations involved are just hash function (h), the bit‐wise exclusive‐or operation (⊕), and the string concatenation operation (||), which are of low computation cost. The security properties discussion and the attacks–resistance power analysis show that the proposed authentication scheme can defend against various typical attacks, especially denial of service attacks. It is sufficiently secure with the lowest computation and storage costs. Furthermore, the formal security proof in SVO logic also demonstrates that the scheme can satisfy the security goals very well. Copyright © 2016 John Wiley & Sons, Ltd.     

低轨星座卫星通信系统中多业务条件下的非充分保证切换策略

该文提出了一种适用于低轨星座卫星通信系统多业务条件下的非充分保证切换策略。该策略在小于一个小区最大驻留时间的时间间隔内为到达小区的呼叫安排和预定信道,在呼叫结束环节作为补充策略对存在切换失败风险的信道进行调整。提出了策略在多业务条件下具体的实施方法,根据实时的切换呼叫性能调整策略的非充分程度。通过仿真,分析比较了不同程度非充分保证切换策略的QoS性能,验证了动态自适应调整非充分程度值的IGH策略的有效性。仿真结果表明,相对于保证切换策略,新策略以存在微小切换失败概率为代价,换取了新呼叫阻塞概率的显著降低,是一种适用于多业务低轨卫星通信系统的信道分配策略。     

图像处理中扩散方程的快速数值解法

该文给出图像处理中常用的二阶非线性扩散方程的快速求解算法。首先提出一种线性差分离散格式,既包含了显格式,也包含了隐格式;其次给出了数值稳定性条件,最后讨论了3种快速解法：多重网格法(MG),交替方向隐格式(ADI),和加性算子分离格式(AOS)。对3种方法进行了比较和评价,结果表明：用3种方法得到的去噪效果基本相同;ADI和AOS实现较简单;多重网格法得到的恢复图像在光滑区域视觉上优于两种直接法。     

A Guard Code Scheme for Handover Traffic Management in WCDMA Systems

A key performance indicator of mobile wireless networks is failure probability of handover calls. In this paper, we propose a Call Admission Control policy which prioritizes handover calls over new calls in WCDMA systems. The OVSF code occupancy of the system is modeled by a Markov chain and the differentiation between handover and new calls is performed at the code level by introducing a “guard code” scheme. The scheme belongs to the well-known family of guard channel schemes and reserves some code capacity to favor the continuation of handover calls over the new calls. As the management of the general case is intractable, we solve certain numerical instances of the problem and manage to calculate several performance metrics like new call blocking and handover failure probabilities and code utilization. We complete our study with simulation results in the case of higher OVSF code tree capacity.

吐哈油田开关站优化设计方案

随着吐哈油田的进一步勘探开发，油田开关站周边负荷快速增长。为了解决新增负荷的供电问题，优化原电网结构．通过技术和经济分析论证．提出了开关站区域供电网优化设计方案，并付诸实施应用。本文针对该方案的合理性和实用性进行了综合分析和探讨．对其实施效果和未来效益方面做了一定程度的阐述。     

小波提升算法及其在图像处理中的应用

小波提升算法是一种新的双正交小波构造方法，通过预测算子，确定高频信息，并初步确定低频信息，然后通过更新算子，对初步确定的低频信息进行修正，从而确定低频信息。它在空域对信号进行变换，完成了对信号频域的分析。在图像处理中，基于离散小波变换的提升算法比传统的卷积算法运算简单，实时性好，易于实现，因而被新一代图像压缩标准JPEG2000所采用。文中简要介绍了小波提升算法的原理，分析了其特点，并介绍了JPEG2000标准中采用的W5／3、D9／7两种小波的提升格式和实现算法。     

基于提升框架的整数小波变换

提升框架可以从一个新的角度来构造小波滤波器,它的核心是确定预测算子和更新算子。该文 引进了多项式局部拟合方法来求取预测算子和更新算子,对每步提升下取整,就实现了整数小波变换。仿真结果表明,该方法应用于二维数字图像,在一定失真的前提下,具有较高的压缩比,而且小波系数与尺度系数都是整数,不需要量化步骤。因此,它对于整数数据压缩具有重要的意义。