重要信息系统的灾难恢复刍议

现代社会和生活越来越依赖于IT系统,信息系统遭到灾难和毁灭性打击将是社会公众的灾难和噩梦。美国“9.11”事件中纽约交易所成功实施了信息服务灾难恢复计划,使得全球对于“业务连续和灾难恢复”有了重新的认识。在我国,信息安全也日益成为政府部门管理层、企业和公众关注的重要话题。企业的弹性、系统的健壮性,信息系统的抗毁性与灾难恢复日益深入人心,风险管理越来越为业界所重视。地震部门在政府应急联动系统中具有重要作用,其本身的信息系统安全已逐步引起重视。     

反倾层状边坡弯曲折断的应力及挠度判据

以地质分析为基础 ,将反倾层状边坡的任意岩层概化为受复合作用力的板梁模型 ,通过简单的力学解析 ,开展了反倾层状岩石边坡弯曲折断判据的研究。依据岩层折断时和相临岩层的瞬时关系 ,将岩层下部视为瞬时临空状态 ,考虑岩层自重荷载和上部岩层附加荷载 (上部岩层重力荷载、层间摩擦力 )的共同作用 ,基于最大拉应力准则 ,提出了岩层弯曲折断的应力判据 ;依据应力判据 ,得到了岩层弯曲折断的挠度判据 ;利用应力判据及挠度判据 ,可实现反倾层状边坡弯曲折断的现场判定及其控制设计     

德国能源转型进程及对中国的启示

总结发达国家能源转型过程中的经验和教训,对中国推动能源转型和实现“双碳”目标具有重要意义。文中回顾了中国和德国电力结构的演变进程,阐述了中国和德国能源转型的机制,并以2022年3月19日为例,分析了德国电力系统灵活性调节的经验。研究表明,健全的法律体系为德国能源转型提供了重要保障,“煤炭委员会”和相关财政支持有效解决了煤电转型过程中的问题,电力市场化是发展可再生主体新型电力系统的重要前提,风力和光伏发电精准预测与管理是可再生能源消纳的关键,煤电和互联互通的欧洲电网是当前德国电力供给的重要保障,过于激进的退煤去核战略是造成2022年德国能源危机的重要原因。最后,从法律保障、市场改革和可再生能源预测与管理等方面提出了中国能源转型的政策建议。     

Flexibility, technology, and the daily life practices of distance students living beyond the digital mainstream

In this paper it is argued that even though communication technologies release distance students considerably from their dependency on a campus, students are still very much connected to places in their daily lives. These connections are constituted through the “placing” of technology, the students’ relations to people in their daily lives and the students’ relations to the education institution. Communication technology not only releases students from the spatial dimensions; it also attaches them to specific places. It is argued that the use of technology in distance education can reduce the students’ flexibility even if they do not have to attend campus regularly. The empirical analysis presented in this paper is based on a case study of a Master’s degree programme in Public Management offered by Open University Indonesia (Universitas Terbuka).     

Accounting for flexibility against uncertain baselines: lessons from case studies in the eastern European energy sector

Abstract

The Kyoto Protocol defines two project-based flexibility mechanisms: joint implementation (JI) and the cleandevelopment mechanism (CDM). The main methodological problem associated with both these mechanisms isthe choice of an appropriate baseline: since the baseline is, by definition, counterfactual, it imposes considerable uncertainty on the accounting framework. Little work to date has been carried out on trying to estimate how largethis uncertainty might be for particular project types. This paper aims to fill this gap by proposing an approach to baseline construction which explicitly acknowledges this uncertainty. This approach is illustrated through theexamination of pilot JI projects in the energy sector in eastern Europe, and then discussed in terms of its implicationsfor climate policy. The results presented are estimates of the range of counterfactual uncertainty in greenhouse gas emission reductions based on the construction of a number of possible baselines for each project. This range is found to be about ±35% for demand side projects, ±45% for heat supply projects, ±55% for cogeneration projects, and ±60% for electricity supply projects. Estimates of uncertainty in the costs of the pilot projects are also found to be high. The paper discusses the problems arising from such large uncertainty and starts to indicate how this uncertainty may be managed.     

A study on the Local Joint Flexibility (LJF) of two-planar tubular DK-joints in jacket structures under in-plane bending loads

In the present paper, results of a parametric study conducted on the Local Joint Flexibility (LJF) of two-planar tubular DK-joints under In-Plane Bending (IPB) loads are presented. DK-joints are among the most common joint types in jacket substructure of Offshore Wind Turbines (OWTs). A total of 324 finite element (FE) analyses were carried out on 81 FE models under four types of IPB loading in order to investigate the effect of the DK-joint’s geometrical parameters on the LJF factor (f_LJF). Based on the results of parametric study, the factors leading to the LJF reduction were introduced. Generated FE models were verified using the existing experimental data, FE results, and parametric equations. The effect of the weld profile was also considered. The f_LJF in two-planar DK- and uniplanar K-joints were compared. Results indicated that the effect of multi-planarity on the LJF is quite significant and consequently the use of the equations already available for uniplanar K-joints to calculate the f_LJF in two-planar DK-joints may lead to highly under-/over-predicting results. To handle this issue, the FE results were used to derive a set of parametric equations for the prediction of the f_LJF in IPB-loaded two-planar DK-joints. The proposed equations were checked against the acceptance criteria recommended by the UK DoE and can be reliably used for the analysis and design of tubular joints in OWTs.     

Making Manchester `flexible': competition and change in the temporary staffing industry

According to local economic and political commentators, Manchester's economy is booming. Employment is growing, investment is on the up, people are moving back into the city centre, and in 2002 the city hosted the largest multi-sporting event to be held in England since the 1948 Olympics. Local economic and political actors point to the wave of economic optimism that has accompanied the `entrepreneurial turn' performed in the late 1980s by the city's political institutions. As part of this, emphasis switched away from Manchester's industrial past and to its possible post-industrial futures. The city council stopped talking defensively--about `defending jobs'--and begun to talk about `making things happen'. New-style political strategies focused on raising the profile of the city, through sustained marketing strategies aimed at selling Manchester as a flexible, twenty-first century consumer-orientated city, despite the loss of 90,000 jobs between 1991 and 1997 and the profound restructuring of the city's economic base. As part of this contradictory process of politically talking up the economy while it has struggled to perform, this paper argues that the conditions have been created in which Manchester's temporary staffing industry has been able to thrive. The first English city to regulate the earliest incarnation of temporary staffing agencies, employment bureaux, and hence with a long established `industry' as such, this paper exams the newly re-energised Manchester temporary staffing industry, and sets out some of the ways in which it is restructuring.     

考虑加筋与遮帘效应的层状地基群桩沉降计算

桩群在土中的加筋与遮帘效应是客观存在的,但目前的理论与实践均未能或有效地考虑该效应.基于剪切变形法原理,在计算某一根桩沉降时,考虑了其他各相邻基桩的存在对该桩沉降的折减,即加筋与遮帘效应,得到了桩侧桩-土接触等效剪切弹簧刚度,建立了桩身位移微分方程,分别求得桩顶沉降-桩端沉降、桩顶荷载-桩端压力的递推关系,从而得到了各桩在自身荷载作用下引起自身沉降的柔度系数; 同理,也求得了各邻桩在其桩顶荷载下引起它桩沉降的柔度系数,最终建立了群桩沉降计算的柔度矩阵方程.推导过程中,考虑了地基土的成层性及桩端沉降的相互影响,并提出了基于一定深度内的Mindlin位移解且考虑桩径影响的桩端压力-桩端位移关系新模式.算例结果表明,本文方法与实测值较为接近,且按本文方法求得的群桩中基桩相互作用系数明显小于弹性理论计算结果,且与实测值吻合较好.