基于统一身份认证的数据加密技术在网络安全中的应用简

随着计算机技术的不断发展,网络应用到生活中的各个方面,网络在广泛应用的同时,网络安全问题也越来越多,使得用户在网络应用中要不断的进行身份认证来保证自身数据的安全。然而重复进行身份认证过程繁琐,同时也存在数据信息泄露的安全隐患,因此,提出了统一身份的认证系统。本文主要对统一身份认证系统和数据加密技术进行介绍,并对kerboeros网络认证协议的认证过程进行探讨,旨在提高网络的安全性。     

循环经济的生态化学工程技术支撑

阐述了循环经济的工程科学内涵及循环经济的技术支撑体系,着重论述了生态化学工程对实施循环经济的技术支撑作用.     

锌/碳纳米管复合电沉积薄膜性能研究

通过复合电沉积技术制备了纳米叠层锌/碳纳米管和光亮锌/碳纳米管2种复合薄膜,薄膜的拉曼光谱验证了锌与碳纳米管的共沉积。薄膜表面的场发射扫描电子显微镜观测显示碳纳米管表面的金属包覆层连续且均匀,预示着良好的界面结合。在2种薄膜的断口和裂纹处分别发现了被拔出基体和桥联的碳纳米管,证实了碳管对基体具有有效的增强作用。     

Quantized output feedback stabilization of uncertain systems with input nonlinearities via sliding mode control

This paper is concerned with the quantized output feedback stabilization problem for a class of uncertain systems with nonsmooth nonlinearities in the actuator device via sliding mode control schemes. It is assumed that system signals are quantized before being transmitted through communication channels. First, a dynamical compensator is developed to estimate unmeasurable system state. Then a sliding surface, in the augmented space using the system output and the estimated state, is proposed, and an adaptive sliding mode control scheme with a static adjustment law of the quantization parameter is established. It is shown that the proposed quantized feedback control strategy is able to tackle parameter uncertainty, external disturbances, and nonsymmetric input nonlinearity simultaneously and guarantees the reachability of the sliding modes of the uncertain system. Finally, an example is given to verify the validity of the theoretical results. Copyright © 2012 John Wiley & Sons, Ltd.     

Asynchronous fault detection filter design approach for discrete‐time switched linear systems

This paper is concerned with the problem of the fault detection filter design for discrete‐time switched linear systems with average dwell‐time. The designed fault detection filters are also switched systems, which are assumed to be asynchronously switched with the original switched systems. Improved results on the weighted l₂ performance and the H _? performance are first given, and the multiple Lyaounov‐like functions during matched period and unmatched period for the running time of one subsystem are used. By the aid of multiple Lyapunov‐like functions combined with Projection Lemma, the FD filters are designed such that the augmented systems under asynchronous switching are exponentially stable, and the residual signal generated by the filters achieves the weighted l₂‐gain for disturbances and guarantees the H _? performance for faults. Sufficient conditions are formulated by linear matrix inequalities, and the filter gains are characterized in terms of the solution of a convex optimization problem. Finally, examples are provided to demonstrate the effectiveness of the proposed design method. Copyright © 2012 John Wiley & Sons, Ltd.     

Crystallization Behaviors of amino-terminated polyurethane (ATPU)-grafted polypropylene

Summary A melt-grafting approach was employed to prepare a novel functional polypropylene(FPP)—amino-terminated polyurethane grafted polypropylene (PP-g-ATPU). The crystallization behaviors of PP and PP/FPP blends were characterized using differential scanning calorimetry (DSC), wide angle X-ray scattering (WAXS) and polarized optical microscopy (POM). The effects of FPP composition on crystallization behavior, crystal transformation, and morphology of PP/FPP crystalline were investigated. The results showed that at a low dosage (<2.0 wt%) ATPU acted as a heterogeneous nucleation agent during the crystallization of PP/FPP blends. However, when the content of ATPU reached 2.0 wt% or higher, ATPU deteriorated the crystallization of PP or PP/FPP blends. The crystallite size decreased and the number of crystallites increased as the ATPU content increased. The Avrami analysis was adopted to describe the isothermal crystallization process. The difference in the exponent n between PP and PP/FPP suggested that the isothermal crystallization kinetics of PP/FPP blends followed a three-dimensional growth via heterogeneous nucleation. In terms of the half-time of the crystallization, t_1/2, the crystallization rate of functional PP blends was faster than that of PP homopolymer at a given crystallization temperature.     

Polyurethane‐infiltrated carbon foams: A coupling of thermal and mechanical properties

The thermal and mechanical properties of polyurethane‐infiltrated carbon foam of various densities were investigated. By combining the high thermal conductivity of the carbon foam with the mechanical toughness of the pure polyurethane, a mechanically tough composite (relative to the unfilled foam) that could be used at higher temperatures than the polyurethane's degradation was formed. Both the tensile strength and the modulus increased by an order of magnitude for the composites compared to unfilled foam, while the compressive and shear strengths and moduli of the composites approached values exhibited by pure polyurethane. At both 300 and 400°C, the rectangular blocks of pure polyurethane lost their mechanical integrity due to decomposition in air. Thermogravimetric analysis confirms substantial initial weight loss above 290°C. Filled carbon foam blocks, however, maintain their mechanical integrity at both 300 and 400°C indefinitely, although the bulk of the rectangular block mass is polyurethane. Three different carbon foam densities are examined. As expected, the higher density foams show greater heat transfer. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2348–2355, 2003     

基于Android平台的盲人手机系统设计与开发

人们生活中的绝大部分信息都是通过视觉获得的,所以盲人能够从外界获取的信息量很少,但这并不能阻止他们努力提高生活质量的渴望。智能手机的快速发展给盲人提供了前所未有的机遇。开发盲人手机具有极大的应用价值。该文主要介绍了在Android平台上设计和实现的一款盲人手机系统,该系统使用了语音识别、语音合成及Web Service等相关技术,实现了语音拨打电话、语音接听电话、语音发送短信、语音播报来电短信、语音报时、语音播报日期和语音播报天气等功能,并能在Android手机中稳定运行,方便盲人使用手机,具有较高的实用价值。     

基于小波分析的储粮害虫图像去噪研究

以储粮害虫为研究对象,阐述了小波去噪的基本原理和高频系数置零、硬阈值法、软阈值等几种方法,并提出了一种改进的小波阈值去噪方法,比较了这几种方法在粮虫图像去噪上的优缺点。实验结果表明,改进的新阈值方法能更好的去除噪声,收到更好的效果。     

数据挖掘中聚类算法的研究简

随着信息技术的不断发展,数据挖掘在我们的工作和生活中的应用也越来越广泛,目前聚类算法在数据挖掘中则是一个热点研究领域。本文深入研究了现阶段比较成熟的几种聚类算法,总结了这些算法的优缺点以及适用范围,提出用来评价聚类算法性能优劣的指标,也是今后聚类算法研究的出发点。