The pulse distributed file system

A network of powerful personal computers, linked by a high-speed local area network, is being seen increasingly as an alternative to a traditional centralized time-sharing operating system. The PULSE project is investigating how such a system may be constructed to give the benefits of a self-sufficient personal computer to each user without losing the facilities for communication and sharing of data inherent in centralized systems. In particular, a distributed file system has been built which provides a single global UNIX

1 UNIX is a trademark of Bell Laboratories.

-like hierarchy, with a consistent appearance when accessed from any machine. Replicated copies of files are maintained to improve reliability, increase performance, and enable each machine to run stand-alone, albeit with reduced facilities.     

三维网格模型水印自适应调节算法

为提高三维网格模型嵌入水印的透明性,提出一种基于模型局部几何特征的自适应水印强度调节算法。将网格模型分割为若干局部区域,根据各区域内几何数据的波动情况对水印嵌入强度进行调节。几何误差和视觉失真误差评价结果表明,与非自适应嵌入方法相比,该方法嵌入的水印透明性较高。     

大时延遥操作系统的波变量双边自适应控制

针对通信时延对遥操作系统稳定性和透明性的影响,研究了一种基于双边自适应控制和波变量理论的控制方法。通过设计波控制器保证通信传输模块的无源性,在保证系统稳定的基础上,调节波阻抗系数来提高系统的透明性,并在时延10 s的情况下进行主从端速度、位置和力的跟踪仿真实验,结果表明该方法和已有的双边自适应方法相比既能保证系统稳定且透明性好,达到较好的控制效果。     

透明耐候硬聚氯乙烯抗冲击性研究

研究了聚氯乙烯树脂中润滑剂用量与冲击改性剂种类的不同对熔体状态的影响,探讨并介绍了透明性好、耐候性优良,冲击韧性颇佳的聚氯乙烯制品。     

A Scottish freedom of information regime for a denationalised environment: rhetorical or authentically practical?

This paper provides an evaluation of the Scottish freedom of information regime in the modern denationalised environment. The authors conducted a pragmatic investigation by means of a real-world compliance inquiry which involved, among other things, the electronic submission of standardised requests for information to those local authority arm's-length external organisations which find themselves now subject to the provisions of the Freedom of Information (Scotland) Act 2002. A compliance matrix, with several response measures, recorded the progression and outcome of the requests sent to each named ‘public authority’. The article is also furnished with a contextual overview of the interaction between the home nation FOI regimes and private enterprise with a nod to contemporaneous events. In turn, the paper reveals several quagmires for the operational practicality of FOI in the privatised arena: a pronounced reminder of the difficulties associated with maintaining a functioning and practical FOI regime in light of a myriad of public service delivery models in the denationalised epoch.     

Water services industry reforms in Malaysia

Concerted efforts to reform and transform the water industry in Malaysia began in 2006. It was a visionary effort by the federal government to ensure an adequate supply of clean water to the public and industry. A policy and institutional framework was created to re-invent and transform the water services industry into an efficient and sustainable sector that will play a pivotal role as one of the major components of economic growth. Though minor adjustments may be needed during its implementation, the overall policy direction is pragmatic and viable and has started to produce tangible outcomes.     

SCM: Secure and accountable TLS certificate management

In classical public‐key infrastructure (PKI), the certificate authorities (CAs) are fully trusted, and the security of the PKI relies on the trustworthiness of the CAs. However, recent failures and compromises of CAs showed that if a CA is corrupted, fake certificates may be issued, and the security of clients will be at risk. As emerging solutions, blockchain‐ and log‐based PKI proposals potentially solved the shortcomings of the PKI, in particular, eliminating the weakest link security and providing a rapid remedy to CAs' problems. Nevertheless, log‐based PKIs are still exposed to split‐world attacks if the attacker is capable of presenting two distinct signed versions of the log to the targeted victim(s), while the blockchain‐based PKIs have scaling and high‐cost issues to be overcome. To address these problems, this paper presents a secure and accountable transport layer security (TLS) certificate management (SCM), which is a next‐generation PKI framework. It combines the two emerging architectures, introducing novel mechanisms, and makes CAs and log servers accountable to domain owners. In SCM, CA‐signed domain certificates are stored in log servers, while the management of CAs and log servers is handed over to a group of domain owners, which is conducted on the blockchain platform. Different from existing blockchain‐based PKI proposals, SCM decreases the storage cost of blockchain from several hundreds of GB to only hundreds of megabytes. Finally, we analyze the security and performance of SCM and compare SCM with previous blockchain‐ and log‐based PKI schemes.     

MIM波导结构中的等离激元诱导透明和慢光效应

基于金属/介质/金属(MIM)波导,提出了一种两侧含有双环、四环谐振腔的等离激元波导滤波结构,采用电磁仿真计算了其电磁传输特性,通过场分布分析了透射谱中通带和谷值产生的物理机理。仿真结果表明该结构可实现等离激元诱导透明(PIT),通过改变谐振腔的有效半径,可调节PIT窗口的位置、带宽和慢光效应。计算结果显示在双环和四环谐振结构的PIT窗口,可以实现0.148和0.358ps的信号延迟。这一特性在可调滤波器件、光存储器件和集成光子器件设计上具有潜在应用价值。     

区块链在公益慈善行业的应用研究

信息不公开、不透明是当下公益慈善事业发展面临的痛点与难点。区块链技术天然具有公开透明、可追溯、防篡改的特点,能有效解决公益组织当前面临的问题,是对其进行监督的有效手段,也是推进公益组织治理能力现代化的重要保障。     

Kosha: A Peer-to-Peer Enhancement for the Network File System

The storage needs of modern scientific applications are growing exponentially, and designing economical storage solutions for such applications – especially in Grid environments – is an important research topic. This work presents Kosha, a system that aims to harvest redundant storage space on cluster nodes and user desktops to provide a reliable, shared file system that acts as a large distributed storage. Kosha utilizes peer-to-peer (p2p) mechanisms to enhance the widely-used Network File System (NFS). P2P storage systems provide location transparency, mobility transparency, load balancing, and file replication – features that are not available in NFS. On the other hand, NFS provides hierarchical file organization, directory listings, and file permissions, which are missing from p2p storage systems. By blending the strengths of NFS and p2p storage systems, Kosha provides a low overhead storage solution. Our experiments show that compared to unmodified NFS, Kosha introduces a 3.3% fixed overhead and 4.5% additional overhead as nodes are increased from two to sixteen. For larger number of nodes, the additional overhead increases slowly. Kosha achieves load balancing in distributed directories, and guarantees or better file availability.*This work was supported in part by an NSF CAREER award (ACI-0238379).Troy A. Johnson was supported by a U.S. Department of Education GAANN doctoral fellowship.