碳纤维在水泥基混凝土中的分散性研究

为充分发挥碳纤维在改善基材电导上的作用,及其在水泥基体上必须均匀分布,用硬化试件电阻测试法及新拌料浆法研究了投料顺序、搅拌时间及碳纤维掺量、纤维长度和掺量、水灰比、振动捣实、分散剂等因素对碳纤维分散性的影响,找到了碳纤维在混凝土中单丝态均匀分散的方法.     

远程I/O控制在工程设计中的应用

通过分析远程I/O控制的特点,将远程I/O+DCS控制和全DCS控制2种控制方式进行比较,认为远程I/O+DCS控制方案可实现物理分散控制,且调试、维修费用少,性价比高.以天津陈塘庄热电厂2台300 MW机组设计为例,介绍了该方案的应用情况和使用中应注意的问题,指出远程I/O控制的发展前景.     

The capacity of local government and continuing the decentralized urban regeneration policies in the Netherlands

In the Netherlands many national urban regeneration funds are concentrated in the Investment Budget for Urban Regeneration (a.k.a. IUR), a block grant made to 30 major cities and the 12 provinces for use in the smaller municipalities. IUR 1 covers the period 2000–2004. IUR 2 is based on the experience of IUR 1 and will be effective in the period 2005–2009. The decentralization of urban regeneration policies from central to local government involves more than just decentralizing the budget, as local government also needs sufficient capacity to pursue these policies. This paper will analyse this capacity and establish how far the experience gained from IUR 1 in this domain is incorporated in IUR 2.     

变异系数来度量区块链网络去中心化程度

区块链网络的最主要优点是去中心化,但大多数关于这个问题的研究缺乏量化,而且都没有针对区块链在实践中的去中心化程度进行度量.提出了一种基于统计学中变异系数来量化区块链网络去中心化程度的方法.利用变异系数,计算了出块数量和地址余额的数据离散程度,从而来量化区块链网络(以比特币和以太坊为例)的去中心化程度.计算结果表明,基于...     

一种基于区块链的存储资源可信分配方法

为了摆脱目前大多传统云存储几乎唯一依赖于第三方信任机构的现状,可以采用一种去中心化的模式实现对网络上闲散存储资源的有效整合与优化.区块链具有去中心化、不可篡改、基于多方共识的信任等技术特征,为实现在去中心化模式下的存储资源可信共享方案提供了设计思路.针对目前传统云存储行业的中心化信任模式可能存在的问题,提出一种基于区块...     

Re-thinking industrial work: Computer effects on technical white-collar workers

The dynamics of computerization is actually reorienting itself towards industrial work. Particularly affected will be white-collar work in industry. Large scale unemployment, degradation of work for the masses of workers, as well as better working conditions for small groups of specialists, and increasing control fn work and of the worker by information systems, will be the main consequences.Computerization has at the same time to be understood as a strategy of firms to fight against worsening conditions in their enviroments. Especially the stagnative tendencies in all major western economies force them to produce inside their productive and bureaucratic apparatus, the profits which they cannot find on their markets. The positive possibilities inherent to computerization, for instance for a reduction of socially necessary work or for a thorough self-management of workers, cannot be used or are perverted by the impact of the ruling economic forces.     

区块链系统攻击与防御技术研究进展

区块链作为一种多技术融合的新兴服务架构,因其去中心化、不可篡改等特点,受到了学术界和工业界的广泛关注.然而,由于区块链技术架构的复杂性,针对区块链的攻击方式层出不穷,逐年增加的安全事件导致了巨大的经济损失,严重影响了区块链技术的发展与应用.从层级分类、攻击关联分析两个维度对区块链已有安全问题的系统架构、攻击原理、防御策...     

基于区块链和密码累加器的自我主权身份认证方案

针对现有基于区块链的身份认证方案中存在的认证流程复杂、需要多次区块链操作、链上数据不够精简、身份暴露后无法再次隐藏的问题,提出了一种基于区块链和密码累加器的自我主权认证方案。利用密码累加器成员验证高效性的特点,精简区块链数据存储,降低链上数据交互频率,提高系统性能和可扩展性;同时,提出了一种身份数据二次隐藏的方法,能够再次隐藏已披露的用户数据,进一步提高系统的安全性。经与现有身份认证方案进行对比分析和实验验证,表明该方案具有较低的存储、通信与计算成本和较高的可扩展性和安全性。