基于身份的电子邮件系统

1984年,为了简化密钥管理并取消公钥证书的使用,Shamir提出了基于身份的密码学概念.在这种密码学模式下,用户的身份信息如用户的名字、Email地址或者IP地址可以直接用作用户的公钥.文章基于三个开放源码库:GNU Multiple Precision(GMP)、OpenSSL和IBE库,设计并实现了一个基于身份的电子邮件系统.该系统具有邮件加密、解密、签名、验证功能.     

Real-time Parallel Processing System Design and Implementation for Underwater Acoustic Communication Based on Multiple Processors

ADSP-TS101 is a high performance DSP with good properties of parallel processing and high speed. According to the real-time processing requirements of underwater acoustic communication algorithms, a real-time parallel processing system with multi-channel synchronous sample, which is composed of multiple ADSP-TS101s, is designed and carried out. For the hardware design, field programmable gate array （FPGA） logical control is adopted for the design of multi-channel synchronous sample module and cluster/data flow associated pin connection mode is adopted for multiprocessing parallel processing configuration respectively： And the software is optimized by two kinds of communication ways： broadcast writing way through shared bus and point-to-point way through link ports. Through the whole system installation, connective debugging, and experiments in a lake, the results show that the real-time parallel processing system has good stability and real-time processing capability and meets the technical design requirements of real-time processing.     

Infrared Image Small Target Detection Based on Bi-orthogonal Wavelet and Morphology

An image multi-scale edge detection method based on anti-symmetrical bi-orthogonal wavelet is given in theory. Convolution operation property and function as a differential operator are analyzed,which anti-symmetrical bi-orthogonal wavelet transform have. An algorithm for wavelet reconstruction in which multi-scale edge can be detected is put forward. Based on it, a detection method for small target in infrared image with sea or sky background based on the anti-symmetrical bi-orthogonal wavelet and morphology is proposed. The small target detection is considered as a process in which structural background is removed, correlative background is suppressed, and noise is restrained. In this approach, the multi-scale edge is extracted by means of the anti-symmetrical bi-orthogonal wavelet decomposition. Then, module maximum chains formed by complicated background of clouds, sea wave and sea-sky-line are removed, and the image background becomes smoother. Finally, the morphology based edge detection method is used to get small target and restrain undulate background and noise. Experiment results show that the approach can suppress clutter background and detect the small target effectively.     

Automatic Detection of Steel Bali＇s Surface Flaws Based on Image Processing

A new method to detect steel bali＇s surface flaws is presented based on computer techniques of image processing and pattern recognition. The steel bali＇s surface flaws is the primary factor causing bearing failure. The high efficient and precision detections for the surface flaws of steel ball can be conducted by the presented method, including spot, abrasion, burn, scratch and crack, etc. The design of main components of the detecting system is described in detail including auto-matic feeding mechanism, automatic spreading mechanism of steel ball＇ s surface, optical system of microscope, image acquisition system, image processing system. The whole automatic system is controlled by an industrial control computer, which can carry out the recognition of flaws of steel bali＇s surface effectively.     

Kalman Filter for Generalized 2-D Roesser Models

The design problem of the state filter for the generalized stochastic 2-D Rocsser models, which appears when both the state and measurement are simultaneously subjected to the interference from white noise, is discussed. The wellknown Kalman filter design is extended to the generalized 2-D Roesser models. Based on the method of ＂scanning line by line＂, the filtering problem of generalized 2-D Roesser models with mode-energy reconstruction is solved. The formula of the optimal filtering, which minimizes the variance of the estimation error of the state vectors, is derived. The validity of the designed filter is verified by the calculation steps and the examples are introduced.     

延时容忍网络中基于内容的信息传播机制研究

延时容忍网络(Delay-tolerant Network)是一种实用的受限网络模型,它具有延迟长、网络分割、节点能力受限等特点.在这种网络环境下,由于网络拓扑不断变化,节点间端到端的通信路径并不存在,传统的路由协议无法有效的运作.针对延时容忍网络的特点,提出了一种基于内容的信息传播机制.在该机制中,每个节点根据相遇历史信息决定是否对所获得的信息进行转发.实验结果表明,该信息传播机制在通信延迟和信息开销方面,较传统OCBD协议和Epidemic协议有所提升.     

基于XPE的嵌入式DVR系统的设计与实现

介绍了一种基于XPE的嵌入式DVR系统的设计与实现方法.该系统采用英特尔凌动处理器作为硬件平台,采用Windows XP Embedded with SP2作为软件平台,能有效克服目前嵌入式DVR处理性能有限而PC式DVR配机繁琐与兼容性问题及不稳定因素.详细介绍了XPE操作系统的开发过程以及FBWF写保护功能的原理和实现方法.基于该方案设计的嵌入式DVR系统经过实际测试,达到了预期的设计效果.     

Development of a reference strain approach for assessment of fracture response of reeled pipelines

As a result of recent increase in exploitation of hydrocarbon resources in harsher environments and also installation techniques which utilize the materials plastic deformation capacity, accurate assessment of fracture response of pipelines subject to large plastic strains (e.g., typical of reeled pipes) has attracted particular interest nowadays. In this paper, an approach, based on the evaluation of the J-integral, is developed for assessing the integrity of such pipelines, manifested in a model of a pipeline with a circumferential part-through crack subjected to plastic bending. The proposed approach is an extension of the reference strain method developed earlier by other researchers, and takes advantage of the displacement controlled loading nature in such pipes (thus being suitable for Strain Based Design methodologies), and the resulting high strain levels, which often cause fracture response of the material in the plastic regime. The developed formulation relates the fracture response of the pipe (in terms of the non-dimensionalized J-integral) as a linear function of the axial strain in the pipe at its uncracked state. A series of 300 3D nonlinear finite element models using the ABAQUS software were analyzed in preparation of the equation that could assess the fracture response of such pipes with great accuracy. The resulting equation, calibrated by the finite element results, can predict the fracture response of pipes with a maximum error of 2% for a practical uncracked material strain range of 1.5% ? ε_unc ? 4%.     

PROFINET CBA组件的应用实现

PROFINET是基于工业以太网的开放标准,PROFINET基于组件的自动化（CBA）技术通过采用标准自动化组件实现了分布式自动化系统简单高效的互联。本文研究了PROFINET CBA的通信原理、模型,基于PI组织的PROFINET CBA Runtime Source代码开发了PROFINET CBA自动化组件,实现了PROFINET CBA组件之间的实时通信,对于构建基于PROFINET CBA的分布式通信系统具有一定的工程意义。     

跨校教学在建筑系研究生班设计课程中的应用

本文提倡以人的终身教育为目标的教育思想;结合香港社会和经济特点,介绍了以课题为核心和以网站为基础的高等 教育改革的思想。最后介绍了香港大学建筑系研究生一年级与清华大学和柏林艺术大学的一项合作设计。