uClinux2.6内核在s3c44b0x平台上的移植研究与实践

作为一种常用的嵌入式操作系统,uClinux继承了Linux的很多优点。将uClinux移植到不同的硬件平台已成为嵌入式系统研究的一个基础。该文基于uClinux的2.6内核版本,分析了移植uClinux操作系统的关键技术。该文选择三星公司生产的ARM7架构的S3C44B0处理器芯片为核心的硬件平台,给出了在该平台上的具体移植方法。     

CNGI青海湖系统建设中的若干技术问题

CNGI 青海湖系统支撑青海湖区域的生态保护和多学科交叉融合的科研协作。针对青海湖基础设施种类众多的特点,我们发展了 IPv6 相关关键技术,应用于基础网络环境建设、数据传输、设备管理与状态监控等多个层面,并充分考虑了由此带来的安全隐患,制定了相应安全策略。这些技术可以支持多种传感器构成的 IPv6 网络,并支持 IPv6 的相关应用软件研发,促进大规模、跨领域复杂科学问题研究工作。     

计算机网络安全存在问题及其防范措施研究

随着计算机网络技术的快速发展,计算机网络的应用范围在逐步的扩大,如今已经深入到了人们生产、生活的方方面面。因为计算机网络系统所具有的开放性、信息资源的共享性、通信信道的公用性以及连接形式的多样性等等,使得网络上存在有很多较为严重的脆弱点。网络安全问题以及越来越严峻,需要我们认真对待。     

Impact of Knowledge Representations on Problem-Oriented Learning in Online Environments

The objective of this study was to investigate the impact of knowledge representations on problem-oriented learning in online learning environments. The study compared the impact of knowledge map representation with traditional hierarchical representation with regard to learning memory and problem-solving performance. Twenty-nine students participated in an experiment in which they studied online materials with the goal of solving two programming problems (simple and complex). It was found that participants who used the hierarchical representation read in the depth-first sequence, whereas participants who used the knowledge map representation read in a sequence reflecting the system running mechanism implied by the graphical representation. In addition, participants who used the knowledge map representation had better memory of the learning content, especially about relations between knowledge nodes. When solving the complex problem, participants who used the knowledge map representation made a deeper analysis of the problem and had better problem-solving performance. These results were not significant in the simple problem-solving task.     

A novel reversible robust watermarking algorithm based on chaotic system

Reversible watermarking can be applied to the protection for important digital media, such as medical and military image, it allows the watermark to be extracted and the original image to be restored completely, but reversible watermarking with stronger robustness is seldom discussed in existing literature. In this paper, a novel reversible watermarking algorithm based on chaotic system is proposed; chaotic system is not only used to search space of reversibility of the scheme, but also used to randomly select the position of watermarking embedding. Consequently, the proposed scheme achieves larger threshold space of reversibility and better performance of security. For some specific thresholds, the proposed algorithm is not only reversible, but also has stronger robustness against image compression. The experimental results show that the ergodicity and sensitivity to initial values of chaotic system play an important role in reversible watermarking algorithm, and the proposed scheme can achieve balance between reversibility and robustness with the help of chaotic system.     

A distributed collaborative product design environment based on semantic norm model and role-based access control

With the boom of Internet Technology, it becomes possible to combine designers from different disciplines into one team to support product design globally. In this paper, a distributed collaborative product design environment is presented to support top-down process oriented product design. In conceptual design stage, the artifact is managed by semantic norm model (SNM). In SNM, the designers can define virtual components at early design stage and instantiate those components at later detailed design stage. By role-based access control (RBAC), different roles with corresponding permissions could be assigned to distributed designers, and the designers could concurrently modify different components of the product relevant to his or her roles. Based on the SNM and RBAC system, a distributed collaborative product design environment is developed and the top-down oriented product design process is demonstrated.     

Video archaeology: understanding video manipulation history

Facing the explosive growth of near-duplicate videos, video archaeology is quite desired to investigate the history of the manipulations on these videos. With the determination of derived videos according to the manipulations, a video migration map can be constructed with the pair-wise relationships in a set of near-duplicate videos. In this paper, we propose an improved video archaeology (I-VA) system by extending our previous work (Shen et al. 2010). The extensions include more comprehensive video manipulation detectors and improved techniques for these detectors. Specially, the detectors are used for two categories of manipulations, i.e., semantic-based manipulations and non-semantic-based manipulations. Moreover, the improved detecting algorithms are more stable. The key of I-VA is the construction of a video migration map, which represents the history of how near-duplicate videos have been manipulated. There are various applications based on the proposed I-VA system, such as better understanding of the meaning and context conveyed by the manipulated videos, improving current video search engines by better presentation based on the migration map, and better indexing scheme based on the annotation propagation. The system is tested on a collection of 12,790 videos and 3,481 duplicates. The experimental results show that I-VA can discover the manipulation relation among the near-duplicate videos effectively.     

A novel two-box search paradigm for query disambiguation

Precision-oriented search results such as those typically returned by the major search engines are vulnerable to issues of polysemy. When the same term refers to different things, the dominant sense is preferred in the rankings of search results. In this paper, we propose a novel two-box technique in the context of Web search that utilizes contextual terms provided by users for query disambiguation, making it possible to prefer other senses without altering the original query. A prototype system, Bobo, has been implemented. In Bobo, contextual terms are used to capture domain knowledge from users, help estimate relevance of search results, and route them towards a user-intended domain. A vast advantage of Bobo is that a wide range of domain knowledge can be effectively utilized, where helpful contextual terms do not even need to co-occur with query terms on any page. We have extensively evaluated the performance of Bobo on benchmark datasets that demonstrates the utility and effectiveness of our approach.     

A survey on enhanced subspace clustering

Subspace clustering finds sets of objects that are homogeneous in subspaces of high-dimensional datasets, and has been successfully applied in many domains. In recent years, a new breed of subspace clustering algorithms, which we denote as enhanced subspace clustering algorithms, have been proposed to (1) handle the increasing abundance and complexity of data and to (2) improve the clustering results. In this survey, we present these enhanced approaches to subspace clustering by discussing the problems they are solving, their cluster definitions and algorithms. Besides enhanced subspace clustering, we also present the basic subspace clustering and the related works in high-dimensional clustering.     

Uncertain term structure model of interest rate

Term structure models describe the evolution of the yield curve through time, without considering the influence of risk, tax, etc. Recently, uncertain processes were initialized and applied to option pricing and currency model. Under the assumption of short interest rate following uncertain processes, this study investigates the term-structure equation. This equation is first derived for valuing zero-coupon bond. Finally, analytic solutions of the uncertain interest rate equation are given when the process of interest rate is assumed to be the uncertain counterparts of the Ho-Lee model and Vasicek model, respectively.