On a stochastic sensor selection algorithm with applications in sensor scheduling and sensor coverage

In this note we consider the following problem. Suppose a set of sensors is jointly trying to estimate a process. One sensor takes a measurement at every time step and the measurements are then exchanged among all the sensors. What is the sensor schedule that results in the minimum error covariance? We describe a stochastic sensor selection strategy that is easy to implement and is computationally tractable. The problem described above comes up in many domains out of which we discuss two. In the sensor selection problem, there are multiple sensors that cannot operate simultaneously (e.g., sonars in the same frequency band). Thus measurements need to be scheduled. In the sensor coverage problem, a geographical area needs to be covered by mobile sensors each with limited range. Thus from every position, the sensors obtain a different view-point of the area and the sensors need to optimize their trajectories. The algorithm is applied to these problems and illustrated through simple examples.     

Bounded Model Checking Using Satisfiability Solving

The phrase model checking refers to algorithms for exploring the state space of a transition system to determine if it obeys a specification of its intended behavior. These algorithms can perform exhaustive verification in a highly automatic manner, and, thus, have attracted much interest in industry. Model checking programs are now being commercially marketed. However, model checking has been held back by the state explosion problem, which is the problem that the number of states in a system grows exponentially in the number of system components. Much research has been devoted to ameliorating this problem.In this tutorial, we first give a brief overview of the history of model checking to date, and then focus on recent techniques that combine model checking with satisfiability solving. These techniques, known as bounded model checking, do a very fast exploration of the state space, and for some types of problems seem to offer large performance improvements over previous approaches. We review experiments with bounded model checking on both public domain and industrial designs, and propose a methodology for applying the technique in industry for invariance checking. We then summarize the pros and cons of this new technology and discuss future research efforts to extend its capabilities.     

谁将成为下一个网络赢家

目前正在进行一场竞赛,以期找出下一个网站新秀,能够利用这种铺天盖地的所谓用户自创内容吸引庞大的受众群体;同时,人们也在竞相甄别下一个大趋势,这个趋势将会决定无数网民未来使用网络媒介的方式.5年前,谁会想到博客和社交网络会成为主流?     

Realism, idealization, and potential negative impact of 3D virtual relationships

One hundred and ninety-nine participants, each of whom was currently involved in an intimate relationship within the 3D virtual world of Second Life, completed measures assessing whether they (1) viewed their 3D virtual relationship as an exercise in fantasy or one that had a quality of realism, and (2) perceived the personality characteristics of their 3D partner in more positive or idealized terms than a current or recent real life partner. Additionally, 71 of the 199 participants (36%) who were concurrently involved in a real life romantic relationship as well as their Second Life relationship provided data regarding the potential negative impact of Second Life relationships on co-occurring real life relationships. Results indicated that (1) the majority of participants viewed their Second Life relationships as real rather than as a form of game-playing, (2) participants generally reported more positive or idealized personality traits for their Second Life partners compared to their real life partners, and (3) a portion of participants in co-occurring Second Life and real life relationships indicated that their virtual relationship served as an emotional competitor or potential threat to their real life relationship, with the potential for detrimental effects rising as the couple progressively adds non-immersive digital and physical channels of communication to the original 3D relationship.     

On the role of the Facilitator in information security risk assessment

In organisations where information security has historically been a part of management and for which the risk assessment methodologies have been designed there are established methods for communicating risk. This is the case for example in the banking and military sectors. However in organisations where information security is not embedded into management thinking and where the relationship between information security and the business is less clear-cut, communicating the risks to the business is less straightforward. In such circumstances it has been observed during field research that information security risk assessments frequently output findings to which the business cannot relate and the process is consequently often viewed as a “tick box” exercise, as opposed to one that provides real value to the business. In such a situation the information security risk assessment is divorced from the business process and not embedded into the organisation’s processes or thinking. The research for this paper was undertaken in order to identify what needs to be done in order to ensure that businesses of this type find the risk assessment process valuable in practice. Lizzie Coles-Kemp is a postgraduate research student in Computer Science and Richard E. Overill is a Senior Lecturer in Computer Science.     

Nonparametric supervised learning by linear interpolation with maximum entropy

Nonparametric neighborhood methods for learning entail estimation of class conditional probabilities based on relative frequencies of samples that are "near-neighbors" of a test point. We propose and explore the behavior of a learning algorithm that uses linear interpolation and the principle of maximum entropy (LIME). We consider some theoretical properties of the LIME algorithm: LIME weights have exponential form; the estimates are consistent; and the estimates are robust to additive noise. In relation to bias reduction, we show that near-neighbors contain a test point in their convex hull asymptotically. The common linear interpolation solution used for regression on grids or look-up-tables is shown to solve a related maximum entropy problem. LIME simulation results support use of the method, and performance on a pipeline integrity classification problem demonstrates that the proposed algorithm has practical value.     

Reoptimization of the Shortest Common Superstring Problem

A reoptimization problem describes the following scenario: given an instance of an optimization problem together with an optimal solution for it, we want to find a good solution for a locally modified instance.     

Characterizing persistent excitation for the sign-sign equation error identifier

The sign-sign (SS) algorithm is a computationally efficient adaptive identifier, often used in signal processing tasks. It is obtained by introducing signum functions on both the regressor and the prediction error multiplicands in the update kernel of the well-known LMS algorithm. This paper gives a deterministic persistent excitation condition on the regressor sequence which guarantees SS convergence. It also gives conditions under which SS may diverge, and discusses how these persistent excitation conditions may be verified through a finite amount of computations.     

A change management framework for macroergonomic field research

With the proliferation of macroergonomic field research, it is time to carefully examine how such research should be managed and implemented. We argue that the importance of attending to high-quality implementation of field research is equal to that of methodological rigor. One way to systematically manage the implementation process is to adopt a change management framework, wherein the research project is conceptualized as an instance of organization-level change. Consequently, principles for successful organization-level change from the literature on change management can be used to guide successful field research implementation. This paper briefly reviews that literature, deriving 30 principles of successful change management, covering topics such as political awareness, assembling the change team, generating buy-in, and management support. For each principle, corresponding suggestions for macroergonomic field research practice are presented. We urge other researchers to further develop and adopt frameworks that guide the implementation of field research.     

Managing cooperation in e-business systems

E-Business management involves monitoring and controlling all forms of business transactions conducted over the Internet, extranets, and related communications technologies and services. As such, it includes the management of networks, systems, and software applications. E-Business management is beginning to depend increasingly on knowledge of the cooperative aspects of partners in a business chain and the cooperative aspects of stake-holders in e-business operations. The study of cooperation offers many opportunities to apply social network analyses to derive software solutions for the management of e-business. This article provides a methodology and case study that recognises the dimension of cooperation among a multiplicity of organisations, coined “Awareness-based Cooperative Management.” It is aimed towards the design or re-engineering of effective e-business management systems, where the key concept involves the degree of awareness held by e-business stake-holders. Awareness is defined in terms of stake-holder interactions and artefacts used in those interactions such as buyer specifications, requests for proposals, offers, service level agreements, and the like. Since awareness is an indispensable, albeit an inherently vague concept, we cast it and reason about it with the apparatus of fuzzy logic.