Identity-based aggregate signcryption in the standard model from multilinear maps

Signcryption is a public key cryptographic method that achieves unforgeability and confidentiality simultaneously with significantly smaller overhead than that required by “digital signature followed by public key encryption”. It does this by signing and encrypting a message in a single step. An aggregate signcryption scheme allows individual signcryption ciphertexts intended for the same recipient to be aggregated into a single (shorter) combined ciphertext without losing any of the security guarantees.We present an aggregate signcryption scheme in the identity-based setting using multilinear maps, and provide a proof of security in the standard model. To the best of our knowledge, our new scheme is the first aggregate signcryption scheme that is secure in the standard model.     

基于模糊决策图与灰色关联分析的枪械设计方案评价

为了解决产品设计方案评价指标相互影响的问题,提出了一种基于模糊决策图（FDM）与灰色关联分析（GRA）的方案评价方法（FDM-GRA）。该方法将GRA作为评价主体过程,利用模糊认知图表达指标间的影响关系,利用FDM实现指标赋权,通过计算灰色关联度来确定最优方案。该方法弥补了GRA无法表示评价指标之间相互影响的缺点。以枪械设计方案评价为例,验证了该方法的可行性。     

Experimental study and simulation of a three-phase flow stirred bioreactor

In order to obtain the reasonable operating conditions and minimize the power consumption in the stirred bioreactor, the hydrodynamic experiments in the stirred bioreactor have been taken to obtain the basic data. Subsequently, an Eulerian model for the gas–liquid–solid three phase flow in the stirred bioreactor has been proposed and the CFD simulation has been conducted. By comparing the results of experiment and simulation, it can be concluded that the simulation results were consistent with the experimental data. The inner relationship between operating variables and indicators could be obtained by comparing the results of just suspension speed, gas holdup, power consumption and operational maps, further the reasonable operating conditions could be also determined under the minimum power consumption. The operational maps could provide the theoretical foundation for industrial application of the gas–liquid–solid stirred bioreactors under the low solid concentration(no more than 20 wt%).     

Fretting corrosion of tin-plated contacts

The susceptibility of tin-plated contacts to fretting corrosion is a major limitation for its use in electrical connectors. The present paper evaluates the influence of a variety of factors, such as, fretting amplitude (track length), frequency, temperature, humidity, normal load and current load on the fretting corrosion behaviour of tin-plated contacts. This paper also addresses the development of fretting corrosion maps and lubrication as a preventive strategy to increase the life-time of tin-plated contacts. The fretting corrosion tests were carried out using a fretting apparatus in which a hemispherical rider and flat contacts (tin-plated copper alloy) were mated in sphere plane geometry and subjected to fretting under gross-slip conditions. The variation in contact resistance as a function of fretting cycles and the time to reach a threshold value (100 mΩ) of contact resistance enables a better understanding of the influence of various factors on the fretting corrosion behaviour of tin-plated contacts. Based on the change in surface profile and nature of changes in the contact zone assessed by laser scanning microscope (LSM) and surface analytical techniques, the mechanism of fretting corrosion of tin-plated contacts and fretting corrosion maps are proposed. Lubrication increases the life-time of tin-plated contacts by several folds and proved to be a useful preventive strategy.     

Particle Swarm Optimization with Chaos-based Initialization for Numerical Optimization

Particle swarm optimization (PSO) is a population based swarm intelligence algorithm that has been deeply studied and widely applied to a variety of problems. However, it is easily trapped into the local optima and premature convergence appears when solving complex multimodal problems. To address these issues, we present a new particle swarm optimization by introducing chaotic maps (Tent and Logistic) and Gaussian mutation mechanism as well as a local re-initialization strategy into the standard PSO algorithm. On one hand, the chaotic map is utilized to generate uniformly distributed particles to improve the quality of the initial population. On the other hand, Gaussian mutation as well as the local re-initialization strategy based on the maximal focus distance is exploited to help the algorithm escape from the local optima and make the particles proceed with searching in other regions of the solution space. In addition, an auxiliary velocity-position update strategy is exclusively used for the global best particle, which can effectively guarantee the convergence of the proposed particle swarm optimization. Extensive experiments on eight well-known benchmark functions with different dimensions demonstrate that the proposed PSO is superior or highly competitive to several state-of-the-art PSO variants in dealing with complex multimodal problems.     

Technological Aspect of Processing Maps for the AA2099 Alloy

Results of an experimental and modelling study of forming processes in the AA2099 Al–Cu–Li alloy, for a wide range of temperatures, strains and strain rates, are presented. The analyses are based on tensile testing at 20 °C at a strain rate of 0.02 s-1and uniaxial compression testing in the temperature range 400–550 °C at strain rates ranging from0.001 to 100 s-1, for constant values of true strain of 0.5 and 0.9. The stability of plastic deformation and its relationship with a sensitivity of stress to strain rate are considered. The power dissipation efficiency coefficient, g(%), and the flow instability parameter, n B 0, were determined. The complex processing maps for hot working were determined and quantified, including process frames for basic forging processes: conventional forging and for near-superplastic and isothermal conditions. A significant aspect is the convergence of power dissipation when passing through the 500 °C peak.Deformation, temperature and strain-rate-dependent microstructures at 500 °C for strain rates of 0.1, 1, 10 and 100 s-1are described and analysed for the conventional die forging process frame, corresponding to 465–523 °C and strain rates of50–100 s-1.     

MapGIS制图中随意参数底图的矢量校正

基于MapGIS软件系统分析和东准噶尔地区空间多元地学信息找矿预测工作,针对无矢量化随意参数地质图件资料的矢量校正,提出了关键点配准法的底图矢量校正方法;对于无配准矢量化图件的矢量校正,提出了关键点坐标法和关键点距离法2种解决方案。研究表明,采用关键点配准法可有效解决传统单幅底图法存在的累计误差大及工作效率低等问题。对于无配准普通数字化图件的矢量校正,可采用关键点坐标法和关键点距离法实现,前者是解决无配准矢量化图校正的最佳方法,适用于原始底图中有4个或以上的关键点,校正后的图件图元信息准确,后期不需要进行点、线图元参数的调整,具有误差小、效率高的特点;当无配准矢量化图中关键点数量少,不适用关键点坐标法时,可采用关键点距离法进行校正。这3种方法对提高成果资料的利用水平,促进空间多元地学信息找矿预测的有效性和准确率有重要意义。     

Fault Diagnosis in Chemical Process Based on Self-organizing Map Integrated with Fisher Discriminant Analysis

Fault diagnosis and monitoring are very important for complex chemical process. There are numerous methods that have been studied in this field, in which the effective visualization method is still challenging. In order to get a better visualization effect, a novel fault diagnosis method which combines self-organizing map （SOM） with Fisher discriminant analysis （FDA） is proposed. FDA can reduce the dimension of the data in terms of maximizing the separability of the classes. After feature extraction by FDA, SOM can distinguish the different states on the output map clearly and it can also be employed to monitor abnormal states. Tennessee Eastman （TE） process is em- ployed to illustrate the fault diagnosis and monitoring performance of the proposed method. The result shows that the SOM integrated with FDA method is efficient and capable for real-time monitoring and fault diagnosis in complex chemical process.     

一种改进的基于潜在语义索引的文本聚类算法

提出一种改进的基于潜在语义索引的文本聚类算法。算法引入潜在语义索引理论,改进传统的SOM算法。用潜在语义索引理论表示文本特征向量,挖掘文本中词与词之间隐藏的语义结构关系,从而消除词语之间的相关性,实现特征向量的降维。改进传统的SOM算法的局限性,准确给出聚类类别数目的值。实验结果表明,本算法的聚类效果更好,聚类时间更少。     

Characterization of deformation stability of in-situ TiB2/6351 composites during hot compression based on Murty criterion

In situ TiB2 reinforced 6351 Al alloy composites were subjected to compression testing at strain rates and temperatures ranging from 0.001 to 10 s -1 and from 300 to 550℃,respectively,using Gleeble-1500D system.And the associated microstructural transformations and instability phenomena were studied by observations of the optical and transmission electron microscope.The power dissipation efficiency and instability parameter were calculated following the dynamic material model and plotted with the temperatur...