车载自组网中一种支持群签名认证的分布式密钥管理方案

群签名具备良好的匿名认证特性,满足车载自组网信息安全和隐私保护需求。但是,其作废开销较大,不适于在大规模网络环境中应用。为此,本文提出了一种支持群签名认证的分布式密钥管理方案DKM,将车载自组网的覆盖区域划分为若干子区域,车辆周期性地从所在子区域的群管理机构更新群密钥。这样,作废某个成员只需要在其拥有合法密钥的子区域内通告,而不是整个网络,有利于降低作废开销。同时,DKM中的密钥更新机制能够保证车辆的群密钥的私密性,从而避免了车辆与区域群管理机构的授权争议,保持了数字签名的不可否认性。性能分析表明DKM能够显著缩短作废列表长度,同时没有增加认证开销。     

20 kg铝锭铸造机铸模改进方案探讨

为了适应火车全面调速后货运高度的要求，提出了有效的铸模改进方案。对铸模改造前后的使用寿命进行了分析。通过改造达到了降低铝锭垛高的目的，同时延长了铸模的使用寿命。     

Curvilinear grids for WENO methods in astrophysical simulations

We investigate the applicability of curvilinear grids in the context of astrophysical simulations and WENO schemes. With the non-smooth mapping functions from Calhoun et al. (2008), we can tackle many astrophysical problems which were out of scope with the standard grids in numerical astrophysics. We describe the difficulties occurring when implementing curvilinear coordinates into our WENO code, and how we overcome them. We illustrate the theoretical results with numerical data. The WENO finite difference scheme works only for high Mach number flows and smooth mapping functions, whereas the finite volume scheme gives accurate results even for low Mach number flows and on non-smooth grids.     

基于FPGA的高速数据存储系统优化设计

针对遥测系统数据记录装置中数据传输速率与存储速率不匹配的问题,提出Flash的并行存储方案,采用交替双平面的编程方式可以使得存储器的存储速率达到单片Flash最高存储速率的2倍,即60 MB/s;对控制单元FPGA内部双端口RAM的逻辑设计进行改进,解决了数据存储异常的现象。在数据回收方面,提出了多备份的设计思想和备用读数接口的设计方案,已在工程应用中得到成功实践,验证了该数据记录装置的可靠性。     

Single-machine parallel-batching scheduling with family jobs to minimize weighted number of tardy jobs

We consider the problem of scheduling n jobs in batches on a single parallel-batching machine, where the jobs are partitioned into jobs families and the jobs in each family have the same due date. The objective is to minimize the weighted number of tardy jobs. We first devise an efficient pseudo-polynomial time and a fully polynomial time approximation scheme for the weighted problem. Then we present $O(n^2)$-time and $O(n\log n)$-time algorithms for the case where the jobs have the same weight and for the case where the jobs have the same processing time, respectively.     

裂解炉横跨管的设计

裂解炉横跨管的设计对辐射段炉管的变形有较大的影响，通过对己建成投产的裂解炉横跨管的设计及使用情况进行总结，以及对横跨管设计的几个方案进行比较，对横跨管设计提出了比较合理的方案，此方案已在中原，天津等裂解炉的设计中采用，并取得良好效果。     

全自动污泥脱水离心机的电气控制系统

介绍了采用恒差速恒力矩控制方案克服卧螺离心机处理城市污泥时容易产生的堵料问题,介绍了絮凝剂自动制备和添加装置。     

基于EIGamal签名的隐私保护网上交易方案

针对网上交易时的用户个人隐私安全问题,依据不经意传输理论,基于ElGamal签名的不经意签名电子信封(OSBE)模型,提出了一个可保护用户隐私的网上交易数字商品方案.首先用户匿名付费给银行,然后银行将用户订购商品的数字签名发送给用户,接着用户使用数字签名与商家进行不经意信息交互,最后用户得到且只能得到自己订购的数字商品,商家并不知道用户订购何种数字商品.正确性证明和安全性分析结果表明,可以有效地保护用户在网上交易过程中的个人隐私,同时防止商家恶意欺诈行为.该方案签名相对较短,计算量较小,密钥动态变化,安全性更强.     

The mechanism and kinetics of the electrochemical cleavage of azo bond of 2-hydroxy-5-sulfophenyl-azo-benzoic acids

The electrochemical reduction of 2-hydroxy-5-[(4-sulfophenyl)azo]benzoic acid, 2-hydroxy-5-[(3-sulfophenyl)azo]benzoic acid, 2-hydroxy-5-[(2-sulfophenyl)azo]benzoic acid and 2-hydroxy-5-azo-benzoic acid has been carried out in aqueous solutions at glassy carbon electrode using cyclic voltammetry and chronoamperometry. The position of sulfo substituent relative to azo bridge as well as pH of the solution have significant impact on the electrochemical behavior of these compounds. It has been proposed that these compounds are reduced predominantly as hydrazone tautomers resulting in corresponding hydrazo compounds. The overall electrochemical reduction follows DISP2 mechanism, ultimately leading to the 5-amino salicylic acid and sulfanilic acid. The rate determining step is the homogenous redox reaction between intermediate hydrazo compound and 5-amino salicylic acid quinoneimine. The mechanism is proposed in which activated complex of 5-amino salicylic acid quinoneimine and intermediate hydrazo compound is formed with the simultaneous loss of one proton.     

Numerical solution of viscous flow past a solid sphere with the control volume formulation

The control volume formulation with the QUICK finite difference scheme is used to solveincompressible liquid flow past a solid sphere in terms of stream function and vorticity.Several tech-nical points are addressed on improving the accuracy and efficiency of numerical simulation of similarproblems of fluid flow.In particular,the importance of suitable specification of the distortion func-tion to enforcing the far field boundarv conditions is emphasized.