Visual Analysis of Large Graphs: State‐of‐the‐Art and Future Research Challenges

The analysis of large graphs plays a prominent role in various fields of research and is relevant in many important application areas. Effective visual analysis of graphs requires appropriate visual presentations in combination with respective user interaction facilities and algorithmic graph analysis methods. How to design appropriate graph analysis systems depends on many factors, including the type of graph describing the data, the analytical task at hand and the applicability of graph analysis methods. The most recent surveys of graph visualization and navigation techniques cover techniques that had been introduced until 2000 or concentrate only on graph layouts published until 2002. Recently, new techniques have been developed covering a broader range of graph types, such as time‐varying graphs. Also, in accordance with ever growing amounts of graph‐structured data becoming available, the inclusion of algorithmic graph analysis and interaction techniques becomes increasingly important. In this State‐of‐the‐Art Report, we survey available techniques for the visual analysis of large graphs. Our review first considers graph visualization techniques according to the type of graphs supported. The visualization techniques form the basis for the presentation of interaction approaches suitable for visual graph exploration. As an important component of visual graph analysis, we discuss various graph algorithmic aspects useful for the different stages of the visual graph analysis process. We also present main open research challenges in this field.     

A General Robust MPC Design for the State‐Space Model: Application to Paper Machine Process

Applying model predictive control (MPC) in some cases such as complicated process dynamics and/or rapid sampling leads us to poorly numerically conditioned solutions and heavy computational load. Furthermore, there is always mismatch in a model that describes a real process. Therefore, in this paper in order to prevail over the mentioned difficulties, we design a robust MPC using the Laguerre orthonormal basis in order to speed up the convergence at the same time with lower computation adding an extra parameter “a” in MPC. In addition, the Kalman state estimator is included in the prediction model and accordingly the MPC design is related to the Kalman estimator parameters as well as the error of estimations which helps the controller react faster against unmeasured disturbances. Tuning the parameters of the Kalman estimator as well as MPC is another achievement of this paper which guarantees the robustness of the system against the model mismatch and measurement noise. The sensitivity function at low frequency is minimized to tune the MPC parameters since the lower the magnitude of the sensitivity function at low frequency the better command tracking and disturbance rejection results. The integral absolute error (IAE) and peak of the sensitivity are used as constraints in optimization procedure to ensure the stability and robustness of the controlled process. The performance of the controller is examined via the controlling level of a Tank and paper machine processes.     

Ontology‐Based Representation and Modelling of Synthetic 3D Content: A State‐of‐the‐Art Review

An indispensable element of any practical 3D/VR/AR application is synthetic three‐dimensional (3D) content. Such content is characterized by a variety of features—geometry, structure, space, appearance, animation and behaviour—which makes the modelling of 3D content a much more complex, difficult and time‐consuming task than in the case of other types of content. One of the promising research directions aiming at simplification of modelling 3D content is the use of the semantic web approach. The formalism provided by semantic web techniques enables declarative knowledge‐based modelling of content based on ontologies. Such modelling can be conducted at different levels of abstraction, possibly domain‐specific, with inherent separation of concerns. The use of semantic web ontologies enables content representation independent of particular presentation platforms and facilitates indexing, searching and analysing content, thus contributing to increased content re‐usability. A range of approaches have been proposed to permit semantic representation and modelling of synthetic 3D content. These approaches differ in the methodologies and technologies used as well as their scope and application domains. This paper provides a review of the current state of the art in representation and modelling of 3D content based on semantic web ontologies, together with a classification, characterization and discussion of the particular approaches.     

Transmission line maintenance robots capable of crossing obstacles: State‐of‐the‐art review and challenges ahead

Power line inspection and maintenance already benefit from developments in mobile robotics. This paper presents a comprehensive review of the state of the art. It focuses on mobile robots designed to cross obstacles found on a typical transmission line while using the conductor as support for traveling. Promising areas of research and development as well as challenges that remain to be solved are discussed with a view to developing fully autonomous technologies. Maintenance tasks, including inspection and repairs, are identified as high‐value applications in transmission live‐line work. Conclusions are drawn from experience, and the future of mobile robotics applied to transmission line maintenance is discussed. © 2009 Wiley Periodicals, Inc.     

Existence and Controllability Results for a New Class of Impulsive Stochastic Partial Integro‐Differential Inclusions with State‐Dependent Delay

In this paper, we study a new class of impulsive stochastic partial integro‐differential inclusions with state‐dependent delay in separable Hilbert spaces. Firstly, by using stochastic analysis theory, analytic resolvent operators, fractional powers of closed operators and suitable fixed point theorems, we prove the existence of mild and extremal mild solutions for these systems in the α‐norm. Secondly, we establish the controllability of the controlled stochastic partial integro‐differential inclusions with not instantaneous impulses. The results are obtained under the mixed Lipschitz and Carathéodory conditions. Finally, an example is provided to show the application of our results.     

State‐saturated H∞ filtering with randomly occurring nonlinearities and packet dropouts: the finite‐horizon case

This paper deals with the H_∞ filtering problem for a class of discrete time‐varying systems with state saturations, randomly occurring nonlinearities as well as successive packet dropouts. Two mutually independent sequences of random variables that obey the Bernoulli distribution are employed to describe the random occurrence of the nonlinearities and packet dropouts. The purpose of the addressed problem is to design a time‐varying filter such that the H_∞ disturbance attenuation level is guaranteed, over a given finite‐horizon, for the filtering error dynamics in the presence of saturated states, randomly occurring nonlinearities, and successive packet dropouts. By introducing a free matrix with its infinity norm less than or equal to 1, the error state is bounded by a convex hull so that some sufficient conditions obtained via solving a certain set of recursive nonlinear matrix inequalities. Furthermore, the obtained results are extended to the case when state saturations are partial. Two numerical simulation examples are provided to demonstrate the effectiveness and applicability of the proposed filter design approach. Copyright © 2012 John Wiley & Sons, Ltd.     

State‐Feedback Control for a Class of Timed Petri Nets Subject to Marking Constraints

The paper contributes with an original method of designing a control for discrete event systems modeled by a class of timed Petri nets. Precisely, this work deals with the closed loop control of Timed Event Graphs (TEGs) under specifications expressed with linear marking constraints. The objective of the controller is to limit the number of tokens in some places of these TEGs. The behavior of TEGs is represented by a system of difference equations that are linear in Min‐Plus algebra and the constraints are described by a set of inequalities, which are also linear in Min‐Plus algebra. A formal approach to design control laws that guarantee compliance with these marking constraints is proposed. For this, two sufficient conditions for the existence of control laws are proposed. The computed controls are causal feedbacks, which can be represented by a set of marked and timed places. The proposed method is illustrated in two applications: a manufacturing production line and an assembly system.     

Comparing Emergency Response Infrastructure to Other Critical Infrastructures in the California Bay‐Delta of the United States: A Research Note on Inter‐Infrastructural Differences in Reliability Management

This research note summarizes observed similarities, differences, and mixed similarities and differences between emergency responders in California's emergency response infrastructure and control room operators in some other critical infrastructures there. The dissimilarities are all the more striking given the many similarities. The chief difference, we speculate, lies in the conditions on and skills of control room operators to ensure the continuous and safe provision of the critical service in question, even during (especially during) turbulent times – what we have called ‘high reliability management’. This management differs considerably from the active crisis management of many emergency responders, although both groups seek to manage ‘reliably’.     

节能办公柯尼卡美能达引领环保新潮流

随着世界经济的发展,越来越多的国家和地区意识到环保的重要性.而随着世界环境日的来临,节能环保更是受到了社会各界的广泛关注.早在2009年4月环境保护部就发布了今年世界环境日的中国主题"减少污染-行动起来",旨在引导公众关注污染防治,积极参与到节能减排工作中来.     

节能办公柯尼卡美能达引领环保新潮流

随着世界经济的发展,越来越多的国家和地区意识到环保的重要性。而随着世界环境日的来临,节能环保更是受到了社会各界的广泛关注。早在2009年4月环境保护部就发布了今年世界环境日的中国主题"减少污染-行动起来",旨在引导公众关注污染防治,积极参与到节能减排工作中     

A semantic interoperability approach to health‐care data: Resolving data‐level conflicts

The integration of data from various electronic health record (EHR) systems presents a critical conflict in the sharing and exchanging of patient information across a diverse group of health‐oriented organizations. Patient health records in each system are annotated with ontologies utilizing different health‐care standards, creating ontology conflicts both at the schema and data levels. In this study, we introduce the concept of semantic ontology mapping for the facilitation and interoperability of heterogeneous EHR systems. This approach proposes a means of detecting and resolving the data‐level conflicts that generally exist in the ontology mapping process. We have extended the semantic bridge ontology in support of ontology mapping at the data level and generated the required mapping rules to reconcile data from different ontological sources into a canonical format. As a result, linked‐patient data are generated and made available in a semantic query engine to facilitate user queries of patient data across heterogeneous EHR systems.     

The Qualitative Properties of Symmetric Open‐Loop Nash Equilibria in the State‐Control Dynamic System in Differential Games

The local stability, steady state comparative statics, and local comparative dynamics of symmetric open‐loop Nash equilibria in the state‐control dynamic system for a seemingly ubiquitous class of discounted infinite horizon differential games are investigated. It is shown that most of the useful qualitative results occur because the same small number of assumptions is being made about the mathematical structure of the integrand and/or state equations. Applications of the results to exhaustible resource extraction and capital accumulation differential games are provided.     

Prescribed performance adaptive neural output control for a class of switched nonstrict‐feedback nonlinear time‐delay systems: State‐dependent switching law approach

This paper investigates the tracking problem for a class of uncertain switched nonlinear delayed systems with nonstrict‐feedback form. To address this problem, by introducing a new common Lyapunov function (CLF), an adaptive neural network dynamic surface control is proposed. The state‐dependent switching rule is designed to orchestrate which subsystem is active at each time instance. In order to compensate unknown delay terms, an appropriate Lyapunov‐Krasovskii functional is considered in the constructing of the CLF. In addition, a novel switched neural network–based observer is constructed to estimate system states through the output signal. To maintain the tracking error performance within a predefined bound, a prescribed performance bound approach is employed. It is proved that by the proposed output‐feedback control, all the signals of the closed‐loop system are bounded under the switching law. Moreover, the transient and steady‐state tracking performance is guaranteed by the prescribed performance bound. Finally, the effectiveness of the proposed method is illustrated by two numerical and practical examples.     

State–space solution to the ℋ︁−/ℋ︁∞ fault‐detection problem

In this paper we give an optimal state–space solution to the ??_?/??_∞ fault‐detection (FD) problem for linear time invariant dynamic systems. An optimal ??_?/??_∞ FD filter minimizes the sensitivity of the residual signal to disturbances while maintaining a minimum level of sensitivity to faults. We provide a state–space realization of the optimal filter in an observer form using the solution of a linear matrix inequalities optimization problem. We also show that, through the use of weighting filters, the detection performance can be enhanced and some assumptions can be removed. Two numerical examples are given to illustrate the algorithm. Copyright © 2011 John Wiley & Sons, Ltd.     

Multi‐level simultaneous multithreading scheduling to reduce the temperature of register files

Simultaneous multithreading (SMT) processors can exploit thread‐level parallelism and at the same time exploit instruction‐level parallelism for multiple‐issue, dynamically scheduled processors. As they have been widely used in embedded systems, reducing their highest temperature has become very important. According to our observation, the register file is always one of the hottest parts of an embedded system. Thus, we present a smart scheduling that can cool an SMT processor effectively by controlling the temperatures of its register files without causing significant performance loss. The proposed approach is fourfold, thus allowing an operating system to dynamically adjust the running workloads based on the temperature threshold and the real‐time constraint. Our experiment was performed on the M‐Sim and HotSpot simulators to evaluate the power of functional units and the temperature impact for SMT processors. In contrast with the round‐robin scheduling, the proposed approach can reduce thermal emergency time by 16.1 and 9.38% of the integer register file and the floating point register file, respectively. Moreover, the proposed approach only degrades performance by 8.8%, which is better than the 22.1% of the throttling approach. Copyright © 2011 John Wiley & Sons, Ltd.     

New behavioral‐level simulation technique for RF/microwave applications. Part III: Advanced concepts

The quadrature modeling structure is widely accepted as an efficient tool for the nonlinear simulation of RF/microwave bandpass stages (power amplifiers, etc.) for wireless applications. The common belief is that this structure can be applied to model only bandpass memoryless nonlinearities (which, however, may exhibit amplitude‐to‐phase conversion). In two recent articles 1 , 2 ; the authors have extended the application of the quadrature modeling structure to modeling broadband nonlinearities, which makes possible to predict harmonics and even‐order nonlinearities, to take into account the frequency response, etc. This article completes the overview of the instantaneous quadrature technique. The authors discuss its application to modeling AM, FM and PM detectors, which are strongly nonlinear elements with large memory (both the strong nonlinearity and large memory effects are essential for the detector proper operation), thus removing the limitation of nonlinearity to be memoryless or quasimemoryless. The identification of nonlinear interference/distortion sources is of great relevance for a practical EMC/EMI design. In the second part of this article, we discuss the dichotomous identification method, which is much more computationally efficient than a simple single‐signal method, especially for a large number of input signals. Individual spectral components of a complex‐spectrum signal can also be considered as input signals and, hence, it is possible to identify the spectral components responsible for a particular nonlinear interference/distortion (say, for a particular intermodulation product). © 2002 Wiley Periodicals, Inc. Int J RF and Microwave CAE 12: 206–216, 2002.     

Response to ‘Comments on: A cohesion measure for object‐oriented classes’

Indicating that CBMC does not satisfy the monotonic property in terms of the number of interactions, Xu and Zhou proposed an augmented definition of CBMC by adopting cut set instead of glue methods. The augmented CBMC clearly satisfies the monotonic property. However, CBMC is designed to overcome the problem with respect to the number of interactions and, therefore, focuses on the interaction pattern, especially, member connectivity. Consequently, it does not make sense to mention the monotonic property of CBMC with respect to interaction number. Moreover, the notion of glue methods allows several interpretations on the design quality of a class. However, that meaningful interpretation is not possible for the augmented definition due to the removal of the notion of glue methods. Copyright © 2001 John Wiley & Sons, Ltd.     

New approach for the analysis and design of negative‐resistance oscillators: Application to a quasi‐MMIC VCO

This article proposes a new approach for the analysis and design of negative‐resistance oscillators using computer‐aided engineering tools. The method presented does not require any special probe and makes the oscillator design similar to the methodology applied to amplifiers. It speeds up convergence and avoids uncertainties in the solution. The negative‐resistance oscillator is split into two parts: an active‐amplifying part and a resonator part. A chain is constructed by linking both parts and repeating them several times, which is known as the repeated circuit simulation procedure. This method allows the separation of the signal flowing between them. Small‐signal AC‐sweep and harmonic‐balance techniques, both available in several commercial software packages, are applied. This method is theoretically justified and shows convergence with less iteration. Furthermore, it is more robust than standard harmonic‐balance probes in the case of multiple frequencies of oscillation. It has been demonstrated in the design of a quasi‐MMIC VCO. This VCO has an external resonator circuit (coaxial resonator and varactor) and a MMIC negative‐resistance circuit, which was manufactured using ED02AH p‐HEMT technology (OMMIC). © 2006 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2006.     

Generation of test sequences from formal specifications: GSM 11‐11 standard case study

This paper presents the results of a case study on generating test cases for a fragment of the smart card GSM 11‐11 standard. The generation method is based on an original approach using the B notation and techniques of constraint logic programming with sets. The GSM 11‐11 technical specifications were formalized with the B notation. From this B specification, a system of constraints was derived, equivalent to this formal model. Using a set constraint solver, boundary states were computed and test cases were obtained by traversing the constrained reachability graph of the specifications. The purpose of this project was to evaluate the contribution of this testing environment, called B ‐TESTING ‐TOOLS , in an industrial process on a real life‐size application, by comparing the generated test sequences with the already used and high‐quality manually‐designed tests. This comparison enabled us to validate our approach and showed its effectiveness in the validation process of critical applications: the case study gives a wide coverage (about 85%) of the generated tests compared to the pre‐existing tests and a saving of 30% in test design time. Copyright © 2004 John Wiley & Sons, Ltd.     

New behavioral‐level simulation technique for RF/microwave applications. Part I: Basic concepts

The quadrature modeling technique is nowadays widely used for the nonlinear simulation of RF/microwave communication circuits and systems at the behavioral (system) level. It allows one to simulate the circuit/system performance under real‐world conditions and signals (using several thousand sample frequencies) and to predict such parameters as adjacent channel power ratio, spectral regrowth, and error vector magnitude in a computationally efficient way. But it is a narrowband technique and, consequently, cannot predict harmonics of the carrier frequency and even‐order nonlinear products, to account for the circuit/system frequency response and the bias decoupling network effect. Here, we propose a new behavioral‐level simulation technique (instantaneous quadrature technique) that overcomes these drawbacks, and demonstrate its validity through measurements and harmonic balance simulation. The transformation of envelope transfer characteristics into instantaneous ones is also discussed in detail. © 2000 John Wiley & Sons, Inc. Int J RF and Microwave CAE 10: 221–237, 2000.