A genetic algorithm for the two-dimensional knapsack problem with rectangular pieces

Given a set of rectangular pieces and a rectangular container, the two-dimensional knapsack problem (2D-KP) consists of orthogonally packing a subset of the pieces within the container such that the sum of the values of the packed pieces is maximized. If the value of a piece is given by its area, the objective is to maximize the covered area of the container. A genetic algorithm (GA) is proposed addressing the guillotine case of the 2D-KP as well as the non-guillotine case. Moreover, an orientation constraint may optionally be taken into account and the given piece set may be constrained or unconstrained. The GA is subjected to an extensive test using well-known benchmark instances. Compared with recently published methods, the GA yields competitive results.     

Evaluating Intrusion‐Tolerant Certification Authority Systems

Various intrusion‐tolerant certification authority (CA) systems have been proposed to provide attack resilient certificate signing (or update) services. However, it is difficult to compare them against each other directly, due to the diversity in system organizations, threshold signature schemes, protocols and usage scenarios. We present a framework for intrusion‐tolerant CA system evaluation, which consists of three components, namely, an intrusion‐tolerant CA model, a threat model and a metric for comparative evaluation. The evaluation framework covers system organizations, protocols, usage scenarios, the period of certificate validity, the revocation rate and the mean time to recovery. Based on the framework, four representative systems are evaluated and compared in three typical usage scenarios, producing reasonable and insightful results. The interdependence between usage scenarios and system characteristics is investigated, providing a guideline to design better systems for different usage scenarios. The proposed framework provides an effective and practicable method to evaluate intrusion‐tolerant CA systems quantitatively, and helps customers to choose and configure an intrusion‐tolerant CA system. Moreover, the comparison results offer valuable insights to further improve the attack resilience of intrusion‐tolerant CA systems. Copyright © 2011 John Wiley & Sons, Ltd.     

Characterisation of the S-Carboxymethyl Extract of Wool Using Small Format Alkaline Urea-PAGE/SDS-PAGE Followed by Silver Staining

Abstract

Alkaline urea-PAGE/SDS-PAGE, when used in a novel format which was significantly smaller than that employed by earlier workers, and when followed by silver staining, resulted in the detection of excellently resolved protein components from S-carboxymethyl reductive extracts of very small wool samples, even samples as small as an individual wool fibre. The silver stained two-dimensional gel patterns exhibited significant improvements compared to the fluorograph gel patterns of earlier workers based on the presence of radiolabel incorporated within the S-carboxymethyl moiety. The silver staining resulted in the visualisation of numerous protein components, and in the region of the gel pattern expected to contain the high-sulfur protein fraction, there appeared more major components than the number of high-sulfur protein components usually displayed in fluorograph patterns. The relative amount of the high-sulfur protein fraction in the final silver stained gel pattern could be boosted, if desired, if the gel was loaded not with the whole wool extract but with the filtrate resulting from the passage of the whole extract through a centrifugal ultrafilter.     

盐酸普罗帕酮的核磁共振谱分析

该文利用核磁共振实验技术详细研究了抗心律失常药物盐酸普罗帕酮的化学结构特征，并借助二维核磁共振实验技术对盐酸普罗帕酮的氢谱和碳谱进行了完全归属，为该类化合物的结构解析提供了有益的分析依据。     

Modeling pedestrian mobility in disaster areas

Realistic mobility modeling is necessary for testing disaster management strategies as well as performance of disaster–resilient networks. Evacuation of the people from a disaster area depends on the environment and type of the hazard which cause certain changes in the pedestrian flows. Although most models focus on the building evacuations or city-scale evacuation planning, there is a need for a mobility model that captures the pedestrians’ movement behavior during evacuation from large and crowded disaster areas such as theme parks.In this paper, we propose a mobility model of the pedestrians in disaster areas. In our application scenario of theme parks, the main mission of the operators is the evacuation of the visitors and providing access to transportation vehicles such as ambulances. We use real maps to generate theme park models with obstacles, roads, and disaster events. We incorporate macro and micro mobility decisions of the visitors, considering their local knowledge and the social interactions among the visitors. We analyze the outcomes of the simulation of our theme park disaster (TP-D) mobility model with simulations of currently used models and real-world GPS traces. Moreover, using the proposed model as a baseline, we analyze the performance of an opportunistic network application.     

二维近红外光谱定量分析内燃机油粘度指数性能的研究

针对常规近红外光谱技术测试内燃机油性能指标的不足,提出了以电压为外扰方式,获取内燃机油二维近红外光谱的技术。对内燃机油样品进行二维相关光谱分析可以定性分析内燃机油粘度等级。使用来自不同厂家、不同质量等级的35个内燃机油样品建立多维偏最小二乘（N-PLS）模型对内燃机油粘度指数进行了预测研究。结果表明，内燃机油的二维近红外光谱中含有与粘度指数相关的信息，使用N-PLS模型能够实现对内燃机油粘度指数的定量分析。该方法的提出为研究复杂对象性能指标的快速检测提供了一种新的技术手段。     

Assessing supply chain robustness to links failure

Supply chain networks need to respond efficiently to operation disruptions, as one of their aims is to guarantee the on time delivery of products. Hence, robustness has become one of the important issues to consider when designing supply networks. There are alternative ways to measure what robustness means in this context. In this paper, we propose a new metric based on the effect on service level of the collapse of active transportation links. Numerical experiments are carried out to understand how different design factors affect robustness. Robustness under a targeted attack is compared with robustness to random failures. Results show that flow complexity (i.e. the number of potential transportation links between supply network nodes) is the most influential factor affecting supply network and its robustness, as well as the service level that can be maintained after disruptions. Thus, diversification both in supply sources and transportation routes seems to be key to robustness.     

Economic effects of regulating the seismic strengthening of older buildings

The marked increase in the awareness of earthquake risk following the Canterbury earthquakes in New Zealand offered a unique opportunity to investigate the economic effect of disaster-mitigation regulations on the commercial building stock. A difference-in-differences (DD) framework was used to determine whether earthquake risk has been capitalized into the property prices of buildings constructed prior to 1976, as a response to the national policy requiring assessment and strengthening (or demolition) of the existing earthquake-prone building stock. A negative externality is found in the policy announcement on affected (pre-1970s) office and retail buildings which caused office buildings to suffer a 12.5% stigma discount. However, retail properties were less impacted suffering a 2.3% stigma loss. The value of the commercial building stock has been affected by the policy. These findings provide policy-makers with timely evidence as to the economic effects of New Zealand’s earthquake-prone buildings policy. Facing losses in property value and financial responsibility for retrofitting their assets, building owners will be looking for a workable set of regulatory and non-regulatory incentives to encourage disaster risk management and protect the built environment.     

两指标AR过程LS估计的渐近正态性

在两指标AR过程的参数估计问题中,LS估计是最基本的参数估计方法之一。本文给出了两指标AR过程LS估计的渐近正态性.     

二维透明片无狭缝假彩色彩虹全息术

本文提出一种新的二维透明片无狭维彩虹全息技术.这种方法是利用一维光栅和玻璃棒代替实狭缝和通过对参考光编码来实现假彩色彩虹全息,从而可以有效地提高光能利用率,本文对这种新方法进行了理论分析和实验验证.