手机钱包业务中的OTA下载安全机制研究

手机钱包业务中提供了空中充值功能,用户从客户端发起充值请求,OTA服务器验证身份后处理请求。国内移动支付领域,多数OTA加解密使用的是DES的变体3DES算法,其密钥相对较短,且有弱密钥。同类算法中,AES性能最好,较大的数据可以利用AES进行分段加密。文章提出基于AES的Mac校验方式,研究双向身份认证机制的原理和流程,并根据OTA下载的功能需求,提出可应用于手机钱包业务中的多级动态密钥方案。     

Y波段固态谐波混频器研究

为了进一步降低太赫兹接收机的噪声,介绍了基于平面肖特基二极管实现低噪声太赫兹谐波混频器的方法。在建立肖特基二极管较为精确的三维模型和电气模型的前提下,引入紧凑型hammer-head 滤波器结构,同时结合低损耗石英固态电路混合集成的方法,研制了220GHz 和250GHz 太赫兹谐波混频器。测试表明:220GHz混频器在205～235GHz工作范围内最低双边带变频损耗小于6.5dB,最低噪声温度小于650K,250GHz 混频器在230～270GHz 工作范围内最低双边带变频损耗小于6.5 dB,最低噪声温度小于900K。     

A Sequential Algorithm for Joint Parameter Estimation and Multiuser Detection in DS/CDMA Systems with Multipath Propagation

A direct sequence (DS) spread spectrum code division multiple access (CDMA) communication system is considered where several users transmit data symbols over different multipath channels. The main objective of this work is the proposal of a sequential algorithm for joint parameter estimation and multiuser data detection. The computationally prohibitive maximization of the log-likelihood function is replaced by a sequential scheme using the multistage detector for recovering the data symbols and the expectation-maximization algorithm for estimating the channel parameters. The performance of the resulting multiuser receiver is evaluated via Monte Carlo simulations using both synthetic as well as measured channel impulse responses. A comparison of the performance with analytical expressions for the single-user single-path case shows that the proposed system is capable of eliminating the near-far effect existing in conventional DS/CDMA systems.     

海水淡化原理及方法综述

介绍了海水淡化的原理和多级闪蒸、反渗透2种常用的海水淡化方法,并且简要回顾了我国海水淡化的研究和技术应用情况。     

关闭-启动型多级适应性休假Mx/G/1排队系统的随机分解

本文采用一种较简单的分析方法,讨论了队长分布的瞬态和稳态性质,得到了队长瞬态分布的拉普拉斯变换的递推表达式和稳态分布的递推表达式,以及稳态队长的随机分解,并给出了服务台闲期、服务台忙循环期的分布函数。     

Parallel Interior Point Schemes for Solving Multistage Convex Programming

The predictor–corrector interior-point path-following algorithm is promising in solving multistage convex programming problems. Among many other general good features of this algorithm, especially attractive is that the algorithm allows possibility to parallelise the major computations. The dynamic structure of the multistage problems specifies a block-tridiagonal system at each Newton step of the algorithm. A wrap-around permutation is then used to implement the parallel computation for this step.     

A Redox-Active Microporous Organosiloxane Containing a Stable Neutral Radical,Trioxotriangulene

A new silyl-substituted trioxotriangulene ( TOT ) neutral radical and corresponding porous organosiloxanes (POSs) were synthesized. The neutral radical exhibited a peculiarly high stability and formed a diamagnetic π-dimer characteristic to TOT neutral radicals stabilized by the strong multiple SOMO-SOMO interaction in both solution and solid states. POSs including TOT units within the organosiloxane-wall were prepared by polycondensation of the silyl groups and formed microporous structures with ∼1 nm-size diameters. Redox ability of TOT units in the POS was demonstrated by the treatment of oxidant/reductant in heterogeneous suspension condition, where the TOT units were reversibly converted between reduced and neutral radical species. Furthermore, the solid-state electrochemical measurements of the POS revealed the reversible multi-stage redox ability of TOT units involving polyanionic species within the organosiloxane-wall.