宽带网满负荷试验对于UniLINK协议的验证

ＵｎｉＬＩＮＫ是一种基于现存有线电视网的介质访问控制层（ＭＡＣ）协议。该协议的设计适用于树型拓扑结构的宽带网络，且支持的距离从主控端到客户端可达１６０公里。ＵｎｉＬＩＮＫ协议基于一种改进的时分多路控制（ＴＤＭ）协议，支持固定、和保留三三种带宽分配策略，且会依据不同的网络负担动态地在三种策略中进行选择。目前，基于该协议的ＬＡＮＣｉｔｙ系列产品在上海有线电视台和上海交大的互联试验中被使用。基于该测试的     

含铝耐热铸铁熔制新工艺的可行性探讨

本文初步探讨了含铝耐热铸铁熔制新工艺的可行性。试验结果表明,应用本文介绍的工艺方法可以使铝的烧损率稳定在8%～9%之间,铸铁无铝的偏析缺陷。此外,可以获得合格的化学成分以及较为满意的显微组织和机械性能。     

NJTxtr—A Computer Program Based on LASER to Monitor Asphalt Segregation

Abstract: This paper describes the research funded by the New Jersey Department of Transportation to develop an automated technology to monitor segregation during construction of hot-mix asphalt concrete pavements. A Laser-based system was used to measure surface texture and to detect segregation. Two segregated test sections and a control test section were tested to evaluate the applicability of Laser texture method to detect and quantify segregation. Laser texture data were gathered from all three sections. Ratios of texture in segregated areas to that in nonsegregated areas were set as the basis for detection of different levels of segregation. By combining the level of segregation and extent of segregation, an AREA index was developed to determine the acceptability of a pavement section. Based on AREA index, pay adjustment factors were proposed to reduce the payment to account for loss of pavement life due to segregation. Further remedial actions were proposed to correct segregated pavement sections with acceptable AREA index. Based on the above concepts, Windows-based computer program NJTxtr was developed to detect and quantify segregation. This computer program uses the Laser-equipment-collected pavement texture data and determines whether the pavement section is acceptable or unacceptable based on the level of segregation within a pavement section, and provides bonus or penalties to the contractor. The paper describes a novel technology using laser and associated software for construction quality control of asphalt concrete pavements. The proposed methodology was applied to detect segregation in an interstate highway section in New Jersey, and this section was repaved based on visual observation and recommendation from this study.     

The question of organizational forensic policy

The objectives of an organization in combination with the formal policy together underpin the strategic direction that any organization will take. We all know that security begins with policy – in other words the rules of play. If policy is sound then the appropriate security measures can be implemented to protect the activities required to achieve the stated objectives as well as maintain the information assurance requirements – availability, integrity, authentication, confidentiality and non-repudiation.     

地理信息系统中管网水力建模

管网计算为节点流量和区块流量的计算提供了网络解决途径,能为自来水公司确定用户的用水来源、及时解决用户投诉提高客户服务质量。文章论述了地理信息系统中城市自来水公司管网计算的基本原理,建立了一个基于节点方程法的管网水力模型,并用经改进的牛顿迭代法实现了对模型求解。     

新能源和可再生能源

本文主要综述新能源和可再生能源中的太阳能、风能、燃料电池、海洋温差发电和可燃冰的原理及应用,以及各国的研究现状和发展动态.     

A new image encryption algorithm based on the high-dimensional chaotic map

Abstract

Because precision degradation of low-dimensional chaos has seriously affected the security of encryption, a high-dimensional chaos is designed for image encryption according to Devaney and topological conjugate definition. The characteristics of the high-dimensional chaotic map are proved by Devaney definition and the security features are analysed. Owing to the periodic defects of Cat map, a new separated Cat map is designed for the confusion process. The bilateral-diffusion scheme is used in the novel image encryption. The experiment analysis shows that the algorithm passes the random and pseudo-random sequence of test standard SP800-22 released by the National Institute of Standards and Technology Commission and the DIEHARD pseudo-random sequence test. And the experiment results demonstrate that the encryption scheme has a high security.     

乌龙茶新品种乌棪的营养成分及感官分析

对乌龙茶新品种乌棪及其嫁接母本大叶乌、黄金桂进行营养成分分析,并对其感官指示及品质指标进行比较,得出初步结论,乌棪的常规营养组成成分与大叶乌、黄金桂无明显差异,滋味及香气较大叶乌为佳,与黄金桂较为接近,同时又有其独特之处,具有较高的推广价值。     

基于最大F距离码的McEliece公钥密码体制

基于F度量,构造了最大F距离码,提出了基于最大F距离码的新McEliece公钥密码系统。合法接收者通过引入一个随机矩阵X作为附加私钥,并把X加入到原始公钥中,从而产生了一个新的公钥,使该密码系统能够有效抗击敌手通过已知的公钥获得私钥的攻击。同时F度量的引入,提高了攻击密钥体积较小的公钥密码系统的复杂度和难度。通过对现有可行攻击方法的分析,说明了基于最大F距离码的新McEliece公钥密码系统是安全可行的。     

What do students do in a F2F CSCL classroom? The optimization of multiple communications modes

This exploratory study analyzes how students use different communication modes to share information, negotiate meaning and construct knowledge in the process of doing a group learning activity in a Primary Grade 5 blended learning environment in Singapore. Small groups of students interacted face-to-face over a computer-mediated communication (CMC) technology called Group Scribbles (GS) to jointly complete a learning task. The lesson designers attempted to optimize the use of CMC technology and face-to-face (F2F) discussion in students’ collaborative learning, with the aim of harnessing the specific features of each medium. Building on notions from communication studies and from interaction analysis, we observed the construction and evolution of the interactions through analyzing the artifacts that were produced by a group of students – in verbal talk, gestures, and sketches drawn and text inscribed in GS. F2F and GS interactions intertwined to support collaborative learning. The findings from this study could inform design aspects concerning integrating and reinforcing the strengths of both communication modes when introducing computer-assisted collaborative learning (CSCL) in a F2F classroom.