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1.
Self-optimizing control is a strategy for selecting controlled variables. It is distinguished by the fact that an economic objective function is adopted as a selection criterion. The aim is to systematically select the controlled variables such that by controlling them at constant setpoints, the impact of uncertain and varying disturbances on the economic optimality is minimized. If a selection leads to an acceptable economic loss compared to perfectly optimal operation then the chosen control structure is referred to as “self-optimizing”. In this comprehensive survey on methods for finding self-optimizing controlled variables we summarize the progress made during the last fifteen years. In particular, we present brute-force methods, local methods based on linearization, data and regression based methods, and methods for finding nonlinear controlled variables for polynomial systems. We also discuss important related topics such as handling changing active constraints. Finally, we point out open problems and directions for future research.  相似文献   

2.
Texture analysis is a very important area in the field of computer vision and related fields. There are a good number of databases developed by different research groups for various texture analysis, in the field of medical analysis, robotics, recognition, analysis, image processing, etc. However, till-to-date, there is no comprehensive works covering the important databases and analyze these in various perspectives. In this paper, we consider this important task so that it becomes helpful for a researcher to choose and evaluate having crucial evaluating aspects in mind. We categorize and critically survey based on many references of the state-of-the-art related to the databases and other texture works. We strongly believe that this elegant survey will be a great contribution for the vision community, especially in the arena of texture analysis.  相似文献   

3.
Next generation heterogeneous wireless networks are expected to interwork with Internet Protocol (IP)-based infrastructures. Conventional network services operate like silos in that a specific set of services are offered over a specific type of access network. It is desirable for users to be able to roam between fixed and mobile networks that employ different access technologies. Therefore, mobility management with quality of service (QoS) support is of particular importance and one of the driving forces of convergence. Since service providers often provide more than one service to their subscribers, it is important to facilitate convergence of network charging architecture through a common charging framework. One of the main issues of IP-based convergence is security and privacy. This requires coordination of different security policies in diverse networks that have different security levels and capabilities. The business case for migration to an IP-based platform motivates operators to deliver more powerful services for customers as well as a better user experience. This paper provides an overview of converged mobile Internet architectures and their implications on QoS, charging/billing and security, as well as emerging business models for telecommunication services.  相似文献   

4.
Decision making is the crucial step in many real applications such as organization management, financial planning, products evaluation and recommendation. Rational decision making is to select an alternative from a set of different ones which has the best utility (i.e., maximally satisfies given criteria, objectives, or preferences). In many cases, decision making is to order alternatives and select one or a few among the top of the ranking. Orderings provide a natural and effective way for representing indeterminate situations which are pervasive in commonsense reasoning. Ordering based decision making is then to find the suitable method for evaluating candidates or ranking alternatives based on provided ordinal information and criteria, and this in many cases is to rank alternatives based on qualitative ordering information. In this paper, we discuss the importance and research aspects of ordering based decision making, and review the existing ordering based decision making theories and methods providing future research directions.  相似文献   

5.
In fuzzy logic in wider sense, i.e. in the field of fuzzy sets applications, t-norms got a prominent rôle in recent times. In many-valued logic, the ?UKASIEWICZ systems, the GÖDEL sytems, and also the product logic all are t-norm based systems. The present paper discusses the more general problem of the adequate axiomatizability for such t-norm based logical systems in general, surveying results of the last years. The main emphasis in the present paper is on propositional logic.  相似文献   

6.
Complex networks have, in recent years, brought many innovative impacts to large-scale systems. However, great challenges also come forth due to distinct complex situations and imperative requirements in human life nowadays. This paper attempts to present an overview of recent progress of synchronization of complex dynamical networks and its applications. We focus on robustness of synchronization, controllability and observability of complex networks and synchronization of multiplex networks. Then, we review several applications of synchronization in complex networks, especially in neuroscience and power grids. The present limitations are summarized and future trends are explored and tentatively highlighted.  相似文献   

7.
We examined the relationships between physical activity and Internet use habits, using the Theory of Planned Behavior (TPB) and the Health Action Process Approach (HAPA) model as a framework. The purpose was to examine how Internet access, digital use, and time spent online correlate with the odds of engaging in three types of PA: strenuous, moderate, and muscle-strengthening Data relied on the Annual Social Survey conducted by Israel's Central Bureau of Statistics in 2010, with 6035 participants aged 20–65. Logistic regressions revealed that the odds of engaging versus not engaging in three types of physical activity were higher among Internet users compared to non-users. The odds of engaging versus not engaging in strenuous physical activity were higher among those who used the Internet for studying, social media, and downloading; in strengthening muscles were higher among those who used the Internet for seeking information and social media; and in moderate physical activity were higher among those who used the Internet for studying, compared to non-users. We suggest that the measured digital uses represent intention and action plans similar in their determinants to being physically active. Health care decision makers should increase availability of information on the Internet regarding a healthy lifestyle, concentrating on leisure-time physical activity habits.  相似文献   

8.
This paper surveys recent results in coverage path planning, a new path planning approach that determines a path for a robot to pass over all points in its free space. Unlike conventional point-to-point path planning, coverage path planning enables applications such as robotic de-mining, snow removal, lawn mowing, car-body painting, machine milling, etc. This paper will focus on coverage path planning algorithms for mobile robots constrained to operate in the plane. These algorithms can be classified as either heuristic or complete. It is our conjecture that most complete algorithms use an exact cellular decomposition, either explicitly or implicitly, to achieve coverage. Therefore, this paper organizes the coverage algorithms into four categories: heuristic, approximate, partial-approximate and exact cellular decompositions. The final section describes some provably complete multi-robot coverage algorithms.  相似文献   

9.
Topology control is a fundamental issue in wireless ad hoc and sensor networks. Due to intrinsic characteristic of flatness, hierarchical topology can achieve the scalability and efficiency of a wireless network. To solve this problem, one can construct a virtual backbone network by using a connected dominating (CDS) set of a wireless network. In past few years, efficiently and fast construct a CDS in a wireless network as a virtual backbone has been the main research problem in hierarchical topology control. In this paper, we give a comprehensive survey for CDSs and related problems with various network models and specific applications. To conclude, some open problems and interesting issues in this field are proposed.  相似文献   

10.
Wireless sensor networks (WSN) are particularly useful for obtaining data concerning events limited to a well-defined geographic region, such as a disaster site or a malfunctioning subsection of a factory plant. Such applications typically use spatial queries, which are SQL-like queries where location constraints are imposed on the collected data. Further, spatial queries allow changing the set of nodes (the region of interest) at runtime. This work surveys spatial queries in WSN. Due to the particular energy and resource constraints of WSN, spatial queries are performed by mechanisms having several stages, each of them implemented using localized distributed algorithms. This article categorizes the existing strategies for each stage, in order to ease the understanding of the state of the art. Finally, we analyze the most recent works on spatial query processing, identifying which classes of algorithms are used on each stage.  相似文献   

11.
Spreadsheet programs can be found everywhere in organizations and they are used for a variety of purposes, including financial calculations, planning, data aggregation and decision making tasks. A number of research surveys have however shown that such programs are particularly prone to errors. Some reasons for the error-proneness of spreadsheets are that spreadsheets are developed by end users and that standard software quality assurance processes are mostly not applied. Correspondingly, during the last two decades, researchers have proposed a number of techniques and automated tools aimed at supporting the end user in the development of error-free spreadsheets. In this paper, we provide a review of the research literature and develop a classification of automated spreadsheet quality assurance (QA) approaches, which range from spreadsheet visualization, static analysis and quality reports, over testing and support to model-based spreadsheet development. Based on this review, we outline possible opportunities for future work in the area of automated spreadsheet QA.  相似文献   

12.
We are currently on a verge of a revolution in digital photography. Developments in computational imaging and adoption of artificial intelligence have spawned new editing techniques that give impressive results in astonishingly short time-frames. The advent of multi-sensor and multi-lens cameras will further challenge many existing integrity verification techniques. As a result, it will be necessary to re-evaluate our notion of image authenticity and look for new techniques that could work efficiently in this new reality. The goal of this paper is to thoroughly review existing techniques for protection and verification of digital image integrity. In contrast to other recent surveys, the discussion covers the most important developments both in active protection and in passive forensic analysis techniques. Existing approaches are analyzed with respect to their capabilities, fundamental limitations, and prospective attack vectors. Whenever possible, the discussion is supplemented with real operation examples and a list of available implementations. Finally, the paper reviews resources available in the research community, including public data-sets and commercial or open-source software. The paper concludes by discussing relevant developments in computational imaging and highlighting future challenges and open research problems.  相似文献   

13.
We present an overview of the most important methods that decompose an arbitrary binary object into a union of rectangles. We describe a run-length encoding and its generalization, decompositions based on quadtrees, on mathematical morphology, on the distance transform, and a theoretically optimal decomposition based on a maximal matching in bipartite graphs. We compare their performance in image compression, in moment computation and in linear filtering. We show that the choice is always a compromise between the complexity and time/memory consumption. We give advice how to select an appropriate method in particular cases.  相似文献   

14.
Live video streaming applications have gained great popularity among users but exert great pressure on video servers and the Internet. Peer-to-Peer (P2P) networks provide an attractive solution due to their low cost and high scalability. A large number of P2P live video streaming schemes have been proposed and many deployments have appeared on the Internet. These schemes pursue vastly diverse directions, from mimicking IP multicast to BitTorrent-like swarming to distributed hash tables. In this paper, we provide a comprehensive and in-depth survey of P2P live video streaming schemes from an algorithmic perspective. Our purpose is to acquaint future designers with the critical design choices and their impacts on system performance. The primary objective of a P2P live video streaming system is to distribute packets from the video source to peers, and the collective paths through which a packet traverses form a tree. We focus on three aspects of how these trees are formed: determining the supplier–receiver relationships for each packet, handling the departure of the supplier or receiver before their relationship expires, and handling lost packets. We identify critical design choices in each aspect and propose a taxonomy according to these choices. Because the surveyed papers use different performance metrics and the reported results are heavily influenced by their experimental settings, we consider two measures to identify the impact of each design choice: we use a set of “internal” metrics in addition to the commonly used “external” metrics, and we examine performance metrics of schemes that have made the same design choice. For better understanding of how the design choices interact with one another and exposing future designers to the design choices specific to each individual scheme, we also provide systematic summaries for a large number of schemes.  相似文献   

15.
The compressed sensing (CS) theory makes sample rate relate to signal structure and content. CS samples and compresses the signal with far below Nyquist sampling frequency simultaneously. However, CS only considers the intra-signal correlations, without taking the correlations of the multi-signals into account. Distributed compressed sensing (DCS) is an extension of CS that takes advantage of both the inter- and intra-signal correlations, which is wildly used as a powerful method for the multi-signals sensing and compression in many fields. In this paper, the characteristics and related works of DCS are reviewed. The framework of DCS is introduced. As DCS's main portions, sparse representation, measurement matrix selection, and joint reconstruction are classified and summarized. The applications of DCS are also categorized and discussed. Finally, the conclusion remarks and the further research works are provided.  相似文献   

16.
《Automatica》1985,21(2):117-128
A survey of the field of optimal sensors and/or controllers location for dynamical distributed parameter systems modelled by partial differential equations is presented. The recent contributions in this field are grouped according to the main goal for which the location problem is developed, namely: system identification, state estimation, and optimal control. In order to pose the sensors and controllers location problem, the semigroup approach for modelling distributed linear systems is briefly reviewed together with its equivalent (infinite dimensional) and approximate (finite dimensional) Fourier expansion representations. After presenting a concise general review of the several methods considered in the current literature, a classification of methods is also proposed. The main classifying factor concerns the use of N-modal approximation schemes, and the different stages of the optimization procedure in which they are required.  相似文献   

17.
18.
Hybrid Energy Sources based on Storage Systems (HES) are increasingly used to improve the grid integration of renewable energy generators, or to improve the energy efficiency and the reliability of transport systems. This paper proposes a survey on the methodologies to design fuzzy logic based supervision strategies of this new kind of energy generating systems. Different ways to manage energy storage system are particularly discussed.A graphical modeling tool is used to facilitate the analysis and the determination of fuzzy control algorithms adapted to complex hybrid systems. The methodology is divided in different steps covering the design of a supervisor from the system work specifications to an optimized implementation of the control.An Experimental Design Methodology (EDM) combined with optimization algorithms is used to tune a set of parameters suitable for a fuzzy supervisor in order to optimize power, energy, efficiency, voltage quality, economic or environmental indicators.The application of this methodology to the supervision of different topologies of HES, based on renewable energy in a grid or in building applications or dedicated to transport systems, illustrates the performance and the systematic dimension of the approach.  相似文献   

19.
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ABSTRACT

Threshold cryptography is a secret sharing technique that finds applications in many fields including cloud computing, authentication, the Internet of Things, ad-hoc and sensor networks, digital signatures, and electronic voting. The technique can effectively reduce the total number of cryptographic keys used for encryption in a group. The article surveys the multifaceted applications of threshold cryptography, portraying the techniques and the secret sharing schemes used. The article also emphasizes the immediate need for reviving the expired Internet Engineering Task Force (IETF) draft of 2010 to establish a threshold cryptography standard.  相似文献   

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