Worst-case control-relevant identification

This paper introduces the reader to several recent developments in worst-case identification motivated by various issues of modelling of systems from data for the purpose of robust control design. Many aspects of identification in H_∞ and ?₁ are covered including algorithms, convergence and divergence results, worst-case estimation of uncertainty models, model validation and control relevancy issues.     

Producing mind

Those who support a computationalist view of the mind tend to hold that it must apply to all aspects of mentality. This view is called computational universalism. An apparently opposed perception-phenomenal universalism-is that consciousness is at the root of all mental processes. Computationalists tend to cognitivize, or otherwise play down, phenomenal consciousness. The recent book by David Chalmers proposes one way to take both computation and phenomenal consciousness seriously. A different way is explored here, which avoids the commitment to a non-materialist ontology of consciousness in Chalmers' position. This alternative approach rejects universalism of both the computational and the phenomenal kinds. Instead a pluralistic view of mind is proposed. Cognitive and phenomenal aspects of mind are to be taken as equally fundamental and as complementary. Cognitive or productive aspects of mind have their own kind of reality which is independent of consciousness. Semantic content may well result from the combination of cognitive productivity and consciousness. The view proposed offers solutions to old problems affecting computational accounts.     

Introduction: New approaches to linear programming

This issue ofAlgorithmica present papers on various aspects of nonlinear methods for solving linear programming problems, inspired by the work of Karmarkar. This introduction describes some of these aspects and briefly mentions other recent developments in the field. A bibliography of recent articles is included.     

Collision Detection for Deformable Objects

Interactive environments for dynamically deforming objects play an important role in surgery simulation and entertainment technology. These environments require fast deformable models and very efficient collision handling techniques. While collision detection for rigid bodies is well investigated, collision detection for deformable objects introduces additional challenging problems. This paper focuses on these aspects and summarizes recent research in the area of deformable collision detection. Various approaches based on bounding volume hierarchies, distance fields and spatial partitioning are discussed. In addition, image‐space techniques and stochastic methods are considered. Applications in cloth modeling and surgical simulation are presented.     

Decision support and control for large-scale complex systems

The technical and social systems of the present day are ever more large, complex and complicated objects. Their models are characterized by numerous state and control variables, time delays, and different time constants. Also they show constraints in their information infrastructure and risk sensitivity aspects. Such systems are called large-scale complex systems (LSS). Hierarchical approach which has been for several decades one of the most utilized methodologies for controlling large-scale systems has evolved in recent years toward more collaborative schemes. When human intervention is necessary, decision support systems (DSS) can represent a solution. A DSS is an adaptive and evolving information system meant to implement several of the functions of a human support team that would otherwise be needed to help the decision-maker to overcome his/her limits and constraints he/she may face when approaching decision problems that count in the organization. This paper aims at reviewing several aspects concerning the utilization and technology of DSS in the context of LSS control. Particular emphasis is put on real-time DSS and multi-participant (group) DSS which support collaborative work. Several advanced solutions such as mixed knowledge systems, that combine numerical methods with AI-based tools, and the prospects of using Ambient intelligence (AmI) concepts in DSS construction are described.     

Pruning backpropagation neural networks using modern stochastic optimisation techniques

Approaches combining genetic algorithms and neural networks have received a great deal of attention in recent years. As a result, much work has been reported in two major areas of neural network design: training and topology optimisation. This paper focuses on the key issues associated with the problem of pruning a multilayer perceptron using genetic algorithms and simulated annealing. The study presented considers a number of aspects associated with network training that may alter the behaviour of a stochastic topology optimiser. Enhancements are discussed that can improve topology searches. Simulation results for the two mentioned stochastic optimisation methods applied to non-linear system identification are presented and compared with a simple random search.     

Illusion—creating a mock reality

Photorealistic computer animation sequences have become more important in recent years in visualization and presentation techniques as well as in fine arts. Some aspects of creating a photorealistic computer animation are demonstrated by the following example of the film Illusion that was created by the computer graphics team at the University of Karlsruhe. An overview of modelling methods, some special effects and details on how to administrate a large computer animation project are presented.     

A Survey of Procedural Noise Functions

Procedural noise functions are widely used in computer graphics, from off‐line rendering in movie production to interactive video games. The ability to add complex and intricate details at low memory and authoring cost is one of its main attractions. This survey is motivated by the inherent importance of noise in graphics, the widespread use of noise in industry and the fact that many recent research developments justify the need for an up‐to‐date survey. Our goal is to provide both a valuable entry point into the field of procedural noise functions, as well as a comprehensive view of the field to the informed reader. In this report, we cover procedural noise functions in all their aspects. We outline recent advances in research on this topic, discussing and comparing recent and well‐established methods. We first formally define procedural noise functions based on stochastic processes and then classify and review existing procedural noise functions. We discuss how procedural noise functions are used for modelling and how they are applied to surfaces. We then introduce analysis tools and apply them to evaluate and compare the major approaches to noise generation. We finally identify several directions for future work.     

The <Emphasis Type="Italic">systems edge</Emphasis> of the Parameterized Linear Array with a Reconfigurable Pipelined Bus System (LARPBS(p)) optical bus parallel computing model

This paper is about exploring the various systems related aspects pertinent in the recent Parameterized Linear Array with a Reconfigurable Pipelined Bus System (LARPBS(p)) model. The two principal features of the LARPBS(p) model is, firstly, its bridging model definition similar to that of the BSP model leading to a more detailed algorithm cost analysis than other models, and secondly, the incorporation of several new communication primitives not defined in earlier models. This paper reviews the systems related aspects of earlier optical bus models and summarizes the LARPBS(p) model. The main part of this paper considers some practical systems related aspects of the LARPBS(p) model, specifically: fiber and free space based implementations, feasibility study, communication traffic analysis, bus collision avoidance, and the cost analysis of a MIMD algorithm. An overview perspective of the work is presented, thereby: the edge of systems related research is identified.

Auto/Autograph

We describe the Auto and Autograph tools for verification and analysis of concurrent systems in their more recent developments. Auto is dedicated to a philosophy of verification by reduction, based on automata morphisms and quotients. Autograph provides a graphical layout on which to display both terms and informations on terms, back and forth to Auto. We stress the openness aspects of both systems and their interface formats to the outside world. We see this as a contribution to the ever growing collaborative trends between similar tools, mostly under the pressure of national or European Esprit projects.     

Observer design for systems with time-delayed states

Recently, the conditions of observers that can estimate directly Kx(t) for an arbitrarily given K, and that are free of the effect of time delayed states of the system, are formulated. This paper points out that, because of the equivalence in formulation, the existing conditions for unknown input observers can be used to establish directly a new set of sufficient conditions for that recent observer. This new set of sufficient conditions is much simpler, and therefore much more useful and significant, than the sufficient conditions derived in that recent paper. This new set of sufficient conditions also reveals some basic mistakes of that recent paper. In addition, this paper reveals the severe restrictiveness of this new set of conditions and proposes a fundamentally new observer design formulation that can relax that set of conditions significantly.     

Quantification of autonomy on multidatabase systems

Amultidatabase system is an interconnected collection of autonomous databases each managed by an autonomous database management system (DBMS). When integrating multiple DBMSs, the key is the autonomy of the underlying participants. Much research has been undertaken in the past five years aimed at describing and building an integrated multidatabase system, but to date the termautonomy has only been defined intuitively. This article provides a rigorous definition for autonomy tailored to the multidatabase environment specifically but applicable to any system environment that involves the collaboration of autonomous participants. The major contribution of this article is a technique that measures autonomy along multiple dimensions so a single numeric value describing the amount of autonomy violated by a particular system design is quantified. This has a two-fold implication. First, the technique described forces researchers to consider autonomy from several different aspects that may not be the central focus of their research, but must be considered because assumptions made regarding one aspect of a system may have implications in other areas. Second, the value can be used as a measure for direct comparison among different systems or proposals. Finally, the article demonstrates the quantification technique's applicability by applying it to several recent multidatabase research efforts.     

Subprofile-aware diversification of recommendations

A user of a recommender system is more likely to be satisfied by one or more of the recommendations if each individual recommendation is relevant to her but additionally if the set of recommendations is diverse. The most common approach to recommendation diversification uses re-ranking: the recommender system scores a set of candidate items for relevance to the user; it then re-ranks the candidates so that the subset that it will recommend achieves a balance between relevance and diversity. Ordinarily, we expect a trade-off between relevance and diversity: the diversity of the set of recommendations increases by including items that have lower relevance scores but which are different from the items already in the set. In early work, the diversity of a set of recommendations was given by the average of their distances from one another, according to some semantic distance metric defined on item features such as movie genres. More recent intent-aware diversification methods formulate diversity in terms of coverage and relevance of aspects. The aspects are most commonly defined in terms of item features. By trying to ensure that the aspects of a set of recommended items cover the aspects of the items in the user’s profile, the level of diversity is more personalized. In offline experiments on pre-collected datasets, intent-aware diversification using item features as aspects sometimes defies the relevance/diversity trade-off: there are configurations in which the recommendations exhibits increases in both relevance and diversity. In this paper, we present a new form of intent-aware diversification, which we call SPAD (Subprofile-Aware Diversification), and a variant called RSPAD (Relevance-based SPAD). In SPAD, the aspects are not item features; they are subprofiles of the user’s profile. We present and compare a number of different ways to extract subprofiles from a user’s profile. None of them is defined in terms of item features. Therefore, SPAD is useful even in domains where item features are not available or are of low quality. On three pre-collected datasets from three different domains (movies, music artists and books), we compare SPAD and RSPAD to intent-aware methods in which aspects are item features. We find on these datasets that SPAD and RSPAD suffer even less from the relevance/diversity trade-off: across all three datasets, they increase both relevance and diversity for even more configurations than other approaches to diversification. Moreover, we find that SPAD and RSPAD are the most accurate systems across all three datasets.

     

Adaptability mechanisms for autonomic system implementation with AAOP

This paper presents a new approach to implementing an adaptability loop in Autonomic Computing (AC) systems, which is based on adaptable aspects. The approach utilizes the concept of adaptable aspect‐oriented programming (AAOP) in which a set of AOP aspects is used to run an application in the manner specified by its adaptability strategy. We present a model execution environment based on this concept, enabling the execution of applications with applied adaptability strategies. In the AAOP‐based AC system, the application is instrumented with aspects selected by the system from a set of all available aspects (sensors, effectors, and goal aspects) in such a way that the system can monitor and manage the application. This model can be used to implement systems that are able to monitor an application and its execution environment, and perform actions such as changing the current set of non‐functional constraints in response to changes in the application or its environment. The model can be used for various types of non‐functional goals, in various programming languages, both in centralized and distributed environments. This paper describes its Java‐based implementation and non‐functional goals referring to resource management. As a consequence, the application uses resources in a way specified in its adaptability strategy. Resource consumption management logic is transparent for the application, meaning that no modifications in the application source code are needed. Copyright © 2010 John Wiley & Sons, Ltd.     

Brains,Bodies, and Beyond: Competitive Co-Evolution of Robot Controllers,Morphologies and Environments

This paper presents a series of simulation experiments that incrementally extend previous work on neural robot controllers in a predator-prey scenario, in particular the work of Floreano and Nolfi, and integrates it with ideas from work on the ‘co-evolution’ of robot morphologies and control systems. The aim of these experiments has been to further systematically investigate the tradeoffs and interdependencies between morphological parameters and behavioral strategies through a series of predator-prey experiments in which increasingly many aspects are subject to self-organization through competitive co-evolution. Motivated by the fact that, despite the emphasis of the interdependence of brain, body and environment in much recent research, the environment has actually received relatively little attention, the last set of experiments lets robots/species actively adapt their environments to their own needs, rather than just adapting themselves to a given environment. This paper is an extended version of: Buason and Ziemke. “Co-evolving task-dependent visual morphologies in predator-prey experiments,” in Genetic and Evolutionary Computation Conference, Cantu-Paz et al. (Eds.), Springer Verlag: Berlin, 2003, pp. 458–469.     

A systems ergonomics analysis of the Maidstone and Tunbridge Wells infection outbreaks

This paper describes a systems ergonomics analysis of the recent outbreaks of Clostridium difficile, which occurred over the period 2005–07 within the UK Maidstone and Tunbridge Wells NHS Trust. The analysis used documents related to the outbreak, alongside the construction of a system model in order to probe deeper into the nature of contributory factors within the Trust. The findings from the analysis demonstrate the value of looking further at cross-level and whole-system aspects of infection outbreaks. In particular, there is a need for further study of the causal relationships that exist between hospital management and clinical management levels within the system. Finally, the paper discusses ways forward and strategies that could be adopted in order to limit the outbreak of hospital-related infections and shape future research. The approach used for the system analysis described in the paper could be used by healthcare practitioners and ergonomists to probe deeper into the causes of infection outbreaks and to extend the scope of interventions aimed at preventing their occurrence.     

基于样本效率优化的深度强化学习方法综述

深度强化学习将深度学习的表示能力和强化学习的决策能力结合,因在复杂控制任务中效果显著而掀起研究热潮.以是否用Bellman方程为基准,将无模型深度强化学习方法分为Q值函数方法和策略梯度方法,并从模型构建方式、优化历程和方法评估等方面对两类方法分别进行了介绍.针对深度强化学习方法中样本效率低的问题进行讨论,根据两类方法的模型特性,说明了Q值函数方法过高估计问题和策略梯度方法采样无偏性约束分别是两类方法样本效率受限的主要原因.从增强探索效率和提高样本利用率两个角度,根据近年来的研究热点和趋势归纳出各类可行的优化方法,分析相关方法的优势和仍存在的问题,并对比其适用范围和优化效果.最后提出增强样本效率优化方法的通用性、探究两类方法间优化机制的迁移和提高理论完备性作为未来的研究方向.     

A Logic for Application Level QoS

Service Oriented Computing (SOC) has been proposed as a paradigm to describe computations of applications on wide area distributed systems. Awareness of Quality of Service (QoS) is emerging as a new exigency in both design and implementation of SOC applications.We do not refer to QoS aspects related to low-level performance and focus on those high-level non-functional features perceived by end-users as application dependent requirements, e.g., the price of a given service, or the payment mode, or else the availability of a resource (e.g., a file in a given format).In this paper we present a logic which includes mechanisms to consider the three main dimensions of systems, namely their structure, behaviour and QoS aspects. The evaluation of a formula is a value of a constraint-semiring and not just a boolean value expressing whether or not the formula holds. This permits to express not only topological and temporal properties but also QoS properties of systems.The logic is interpreted on SHReQ, a formal framework for specifying systems that handles abstract high-level QoS aspects combining Synchronised Hyperedge Replacement with constraint-semirings.     

Extension of domains of states

We deal with categorical aspects of the extensions of generalized probability measures. In particular, we study various domains of fuzzy sets, describe the relationships between σ-fields of crisp sets and generated Łukasiewicz tribes of measurable functions, and mention some probabilistic aspects. D-posets and sequential continuity play an important role. This work was supported by the Slovak Research and Development Agency under the contract No. APVV-0071-06, Protocol for Scientific and Technological Collaboration between the Republic of Italy and Slovak Republic, Project No. 15: Algebraic and Logical Systems of Soft Computing, and VEGA 2/6088/26.