平飞模式双站SAR运动补偿研究

机载双站SAR收、发分置,收、发平台产生的运动误差是独立的,增加了双站SAR运动补偿技术的复杂性.文中建立了平飞模式的双站SAR运动误差模型,在双站模型等效到单站的基础上,对双站SAR运动补偿方法进行了研究,基于模型等效的思路提出了基于回波数据运动补偿的方案.并讨论了PGA自聚焦算法的可行性,给出了相应的计算机仿真.     

基于物元分析的立交方案综合评价方法

针对立交方案的综合评价问题,利用物元分析理论进行研究,提出基于物元分析的立交方案综合评价方法.选取占地面积、通行能力、工程造价、施工难易程度等4大类13个指标作为评价因子,将方案分为优、良、中、一般4个等级,通过确定待评物元、建立节域物元矩阵、经典域物元矩阵,计算各评价因子权重和综合关联隶属度,得到不同方案及各评价因子对4个级别的隶属程度,通过比较选出了整体最优方案.结果表明,将物元分析理论用于立交方案的比选是可行的,不但能够比选出整体最优方案,而且能够分析出各评价因子之间的细微差别,具有较高的精确度.     

Some remarks on the TKIP key mixing function of IEEE 802.11i

Temporal key integrity protocol (TKIP) is a sub-protocol of IEEE 802.11i. TKIP remedies some security flaws in wired equivalent privacy (WEP) protocol. TKIP adds four new algorithms to WEP: a message integrity code (MIC) called Michael, an initialization vector (IV) sequencing discipline, a key mixing function and a re-keying mechanism. The key mixing function, also called temporal key hash, de-correlates the IVs from weak keys. Some cryptographic properties of the substitution box (S-box) used in the key mixing function are investigated in this paper, such as regularity, avalanche effect, differ uniform and linear structure. Moen et al pointed out that there existed a temporal key recovery attack in TKIP key mixing function. In this paper a method is proposed to defend against the attack, and the resulting effect on performance is discussed.     

Filling the gap between voters and cryptography in e-voting

Cryptography is an important tool in the design and implementation of e-voting schemes since it can provide verifiability, which is not provided in the traditional voting. But in the real life, most voters can neither understand the profound theory of cryptography nor perform the complicated cryptographic computation. An e-voting system is presented in this paper to leverage the use of cryptography. It combines the advantages of voting scheme of Moran-Naor and voting scheme based on homomorphic encryption. It makes use of the cryptographic technique, but it hides the details of cryptographic computation from voters. Compared with voting scheme of Moran-Naor, the new system has three advantages: the ballots can be recovered when the voting machine breaks down, the costly cut-and-choose zero-knowledge proofs for shuffling votes made by the voting machine are avoided and the partial tally result in each voting machine can be kept secret. Foundation item: the National Natural Science Foundation of China (No. 60673076) and the National High Technology Research and Development Program (863) of China (No. 2008AA01Z403)     

A novel approach to design robust fault detection filter for networked control systems

In this paper, an approach for designing robust fault detection filter (RFDF) of networked control systems (NCSs) with unknown inputs is studied. The design aims at implementing the optimal trade-off between robustness of unknown inputs (including the item produced by networked-induced delay) and sensitivity of fault. The key design issue is to introduce an optimal fault detection filter based on NCSs with the control law compensation as the reference residual model of NCSs and to formulate the RFDF design as a model-matching problem. By applying H _∞ optimization technique, linear matrix inequality (LMI) approach is given to solve the model-matching problem. The validity of the proposed approach is shown by a numerical example.      

基于转角的电动助力转向系统回正性能控制

针对电动助力转向系统回正效果不理想,通过设计新型转角传感器以及扭矩传感器,采用了基于微处理器控制的回正控制单元和硬件,能够很好的实现转向系统回正.在实验台上进行的在线仿真和实验也表明,在设置不同的阻力环境和车速,转向系统都能够较好的识别,并实施回正和阻尼控制.     

提高水泥混凝土路面施工质量的措施

为了能更好地控制好水泥混凝土路面的质量,笔者以大连至庄河高速公路十号路互通立交收费站水泥混凝土路面工程为例,总结了确保水泥混凝土路面施工质量的关键技术。     

论大学核心价值体系的理论模型及实证研究

本文通过对影响大学核心价值体系因子的梳理,利用层次分析法(AHP)对影响五大价值传播渠道的主要因子进行了详细界定,通过专家调查法确定了各因子相对于上层因子的权重,建立起大学核心价值体系(建设)完善度的数学评估模型.利用该评估模型对上海交通大学进行的实证研究,提供了大学核心价值体系建设方面的具有可操作性的建议.     

预防公交车自燃的措施

预防公交车自燃的关键是把握着自燃的原因机理,提前做好预防措施。1.公交车自燃原因(1)车辆漏油。车辆漏油可以说是引发汽车自燃的重要原因之一,一旦漏油(特别是燃油泄露),混合气达到一定的浓度,加之有明火出现,自燃事故就难以避免。