Unbonded post tensioned concrete in fire: A review of data from furnace tests and real fires

The fire-safe design of concrete structures, which incorporate post-tensioned prestressing tendons, has recently been the subject of debate within the structural engineering community, particularly when unbonded post-tensioned (UPT) prestressing tendons are used. Despite several studies aimed at furthering our understanding of the response of UPT concrete structures in fire, many aspects of their response in real fires remain poorly understood. An exhaustive summary of available test data, which have been used over the past five decades to generate fire design guidance for UPT concrete structures is given. Case studies showing the response of real UPT structures in severe building fires are also discussed. In both cases, the intent is to highlight inadequacies in the current state of knowledge for UPT buildings in fire and to prioritize areas for future research.     

Decoupled Roles for the Atypical,Bifurcated Binding Pocket of the ybfF Hydrolase

Serine hydrolases have diverse intracellular substrates, biological functions, and structural plasticity, and are thus important for biocatalyst design. Amongst serine hydrolases, the recently described ybfF enzyme family are promising novel biocatalysts with an unusual bifurcated substrate‐binding cleft and the ability to recognize commercially relevant substrates. We characterized in detail the substrate selectivity of a novel ybfF enzyme from Vibrio cholerae (Vc‐ybfF) by using a 21‐member library of fluorogenic ester substrates. We assigned the roles of the two substrate‐binding clefts in controlling the substrate selectivity and folded stability of Vc‐ybfF by comprehensive substitution analysis. The overall substrate preference of Vc‐ybfF was for short polar chains, but it retained significant activity with a range of cyclic and extended esters. This broad substrate specificity combined with the substitutional analysis demonstrates that the larger binding cleft controls the substrate specificity of Vc‐ybfF. Key selectivity residues (Tyr116, Arg120, Tyr209) are also located at the larger binding pocket and control the substrate specificity profile. In the structure of ybfF the narrower binding cleft contains water molecules prepositioned for hydrolysis, but based on substitution this cleft showed only minimal contribution to catalysis. Instead, the residues surrounding the narrow binding cleft and at the entrance to the binding pocket contributed significantly to the folded stability of Vc‐ybfF. The relative contributions of each cleft of the binding pocket to the catalytic activity and folded stability of Vc‐ybfF provide a valuable map for designing future biocatalysts based on the ybfF scaffold.     

Long-term fairness with bounded worst-case losses

How does one repeatedly choose actions so as to be fairest to the multiple beneficiaries of those actions? We examine approaches to discovering sequences of actions for which the worst-off beneficiaries are treated maximally well, then secondarily the second-worst-off, and so on. We formulate the problem for the situation where the sequence of action choices continues forever; this problem may be reduced to a set of linear programs. We then extend the problem to situations where the game ends at some unknown finite time in the future. We demonstrate that an optimal solution is intractable, and present two good approximation algorithms.     

高占空比时的Charlie多路复用

最近出现了几篇文章．介绍了一些新奇的方法．旨在增加微处理器借助数量有限的引脚所能驱动的LED的数量（参考文献1）。标准的多路复用方法是由于多位七段显示器而流行起来．而在引脚稀少的设计方案中．它已让位于“Charlie多路复用（Charleplexing）”。     

Marginal abatement costs of greenhouse gas emissions: A meta-analysis

In this paper, we carry out a meta-analysis of recent studies into the costs of greenhouse gas mitigation policies that aim at the long-term stabilisation of these gases in the atmosphere. We find the cost estimates of the studies to be sensitive to the stringency of the stabilisation target, the assumed emissions baseline, the way in which the time profile of emissions is determined in the model, the choice of control variable (CO₂ only versus multigas), the number of regions and energy sources in the model and, to a lesser degree, the scientific “forum” in which the study was developed. We find that marginal abatement costs of the stringent long-term targets that are currently considered by the European Commission are still very uncertain but might exceed the costs that have been suggested by recent policy assessments.     

TRAVOS: Trust and Reputation in the Context of Inaccurate Information Sources

In many dynamic open systems, agents have to interact with one another to achieve their goals. Here, agents may be self-interested, and when trusted to perform an action for another, may betray that trust by not performing the action as required. In addition, due to the size of such systems, agents will often interact with other agents with which they have little or no past experience. There is therefore a need to develop a model of trust and reputation that will ensure good interactions among software agents in large scale open systems. Against this background, we have developed TRAVOS (Trust and Reputation model for Agent-based Virtual OrganisationS) which models an agent’s trust in an interaction partner. Specifically, trust is calculated using probability theory taking account of past interactions between agents, and when there is a lack of personal experience between agents, the model draws upon reputation information gathered from third parties. In this latter case, we pay particular attention to handling the possibility that reputation information may be inaccurate.     

An investigation of train driver visual strategies

Train driving is primarily a visual task; train drivers are required to monitor the dynamic scene visually both outside and inside the train cab. Poor performance on this visual task may lead to errors, such as signals passed at danger. It is therefore important to understand the visual strategies that train drivers employ when monitoring and searching the visual scene for key items, such as signals. Prior to this investigation, a pilot study had already been carried out using an eye tracking technique to investigate train drivers’ visual behaviour and to collect data on driver monitoring of the visual environment, Groeger et al. (2003) Pilot study of train drivers’ eye movements, University of Surrey. However, a larger set of data was needed in order to understand more fully train driver visual behaviour and strategies. In light of this need, the Transport Research Laboratory produced a methodology for the assessment of UK train driver visual strategies, on behalf of the Rail Safety and Standards Board and applied this methodology to conduct a large-scale trial. The study collected a wealth of data on train drivers’ visual behaviour with the aim of providing a greater understanding of the strategies adopted. The corneal dark-eye tracking system chosen for these trials tracks human visual search and scanning patterns, and was fitted to 86 drivers whilst driving in-service trains. Data collected include the duration and frequency of glances made towards different elements of the visual scene. In addition, the train drivers were interviewed after driving the routes, to try and understand the thought processes behind the behaviour observed. Statistical analysis of over 600 signal approaches was conducted. This analysis revealed that signal aspect, preceding signal aspect, signal type and signal complexity are important factors, which affect the visual behaviour of train drivers. Train driver interview data revealed that driver expectation also plays a significant role in train driving. The findings of this study have implications for the rail industry in terms of infrastructure design, design of the driving task and driver training. However, train driving is extremely complex and the data from this study only begin to describe and explain train driver visual strategies in the specific context of signal approaches. This study has provided a wealth of data and further analysis of it is needed to investigate the role of other factors and the complex relationships between factors during signal approaches and other driving situations systematically. Finally, there are important aspects of visual behaviour that cannot be examined using these data or this method. Investigation of other aspects of visual behaviour, such as peripheral vision, will require other methods such as simulation.     

煤层气产量预测和矿区优化的储层模拟

SIMEDⅡ煤层气储层模拟器是一个高精度的，可以对非稳态的储层状态、多组份气体以及三维立体的储层结构进行模拟的软件。本文具体阐述了SIMEDⅡ模拟器的工作流程。以及如何将它应用于预测气体产量以及模拟储层中煤层气的抽采过程。     

Professionals in mutual help groups: Impact on social climate and members' behavior.

This study assessed the impact of professional involvement in mutual help groups for the mentally ill. Social climate data and behavioral data on members in groups led either by a mental health professional (n?=?36) or an indigenous group member (n?=?70) were compared. The results of the study indicated a more formal, psychologically directed approach in the professionally led groups. Although professional involvement in mutual help groups does not necessarily produce different member outcomes, it does seem to affect both the perceptions and the behavior of members. Professionals should be cautious when they get involved in mutual help groups to avoid professionalizing them. (PsycINFO Database Record (c) 2010 APA, all rights reserved)