Various authors propose the use of flow dominance in complexity ratings to evaluate the complexity of facilities layout problems, to determine the choice between computer algorithms and visual based methods for plant ...
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Various authors propose the use of flow dominance in complexity ratings to evaluate the complexity of facilities layout problems, to determine the choice between computer algorithms and visual based methods for plant layout, and to decide on the particular layout configuration (line or process layout) to be installed. This paper examines critically past contributions and casts some serious doubts on the validity of the flow dominance concept and the related measures of layout complexity. It is shown that flow dominance does not serve its intended purpose and that the complexity rating factors suggested in the literature not only show serious problems with regard to their interpretability, but are largely unusable. Finally, the future work needed in this problem area is elaborated.
Markov chains (MCs) are widely used to model systems which evolve by visiting the states in their state spaces following the available transitions. When such systems are composed of interacting subsystems, they can be...
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Markov chains (MCs) are widely used to model systems which evolve by visiting the states in their state spaces following the available transitions. When such systems are composed of interacting subsystems, they can be mapped to a multi-dimensional MC in which each subsystem normally corresponds to a different dimension. Usually the reachable state space of the multi-dimensional MC is a proper subset of its product state space, that is, Cartesian product of its subsystem state spaces. Compact storage of the matrix underlying such a MC and efficient implementation of analysis methods using Kronecker operations require the set of reachable states to be represented as a union of Cartesian products of subsets of subsystem state spaces. The problem of partitioning the reachable state space of a three or higher dimensional system with a minimum number of partitions into Cartesian products of subsets of subsystem state spaces is shown to be NP-complete. Two algorithms, one merge based the other refinement based, that yield possibly non-optimal partitionings are presented. Results of experiments on a set of problems from the literature and those that are randomly generated indicate that, although it may be more time and memory consuming, the refinement based algorithm almost always computes partitionings with a smaller number of partitions than the merge-based algorithm. The refinement based algorithm is insensitive to the order in which the states in the reachable state space are processed, and in many cases it computes partitionings that are optimal.
Because of the complexity of the failure diagnosis for large-scale discrete event systems (DESs), DESs with decentralized information have received a lot of attention. DESs with communication events are defined as dis...
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Because of the complexity of the failure diagnosis for large-scale discrete event systems (DESs), DESs with decentralized information have received a lot of attention. DESs with communication events are defined as distributed DESs. Stochastic discrete event systems (SDESs) are DESs with a probabilistic structure. A-diagnosability is an important property in failure diagnosis of SDES. In this paper, we investigate A-diagnosability in distributed SDESs. We define a local model and global model. Moreover, we construct a synchronized stochastic diagnoser to check A-diagnosability in distributed SDESs. We also propose a necessary and sufficient condition for a distributed SDES to be A-diagnosable. Some examples are described to illustrate our algorithms.
A much beloved and widely Used example showing the elegance and simplicity of lazy functional programming represents itself as "The Sieve of Eratosthenes." This paper shows that this example is not the sieve...
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A much beloved and widely Used example showing the elegance and simplicity of lazy functional programming represents itself as "The Sieve of Eratosthenes." This paper shows that this example is not the sieve and presents an implementation that actually is.
作者：
Ling, Ai-fanJiangxi Univ Finance & Econ
Sch Finance Res Ctr Secur & Future Nanchang 330013 Peoples R China Chinese Acad Sci
Key Lab Management Decis & Informat Syst Acad Math & Syst Sci Beijing 100190 Peoples R China
A heuristic algorithm based on VNS is proposed to solve the Max 3-cut and Max 3-section problems. By establishing a neighborhood structure of the Max 3-cut problem, we propose a local search algorithm and a variable n...
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A heuristic algorithm based on VNS is proposed to solve the Max 3-cut and Max 3-section problems. By establishing a neighborhood structure of the Max 3-cut problem, we propose a local search algorithm and a variable neighborhood global search algorithm with two stochastic search steps to obtain the global solution. We give some numerical results and comparisons with the well-known 0.836-approximate algorithm. Numerical results show that the proposed heuristic algorithm can obtain efficiently the high-quality solutions and has the better numerical performance than the 0.836-approximate algorithm for the NP-Hard Max 3-cut and Max 3-section problems.
Many algorithms for computing minimal coverability sets for Petri nets prune futures. That is, if a new marking strictly covers an old one, then not just the old marking but also some subset of its successor markings ...
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Many algorithms for computing minimal coverability sets for Petri nets prune futures. That is, if a new marking strictly covers an old one, then not just the old marking but also some subset of its successor markings is discarded from search. In this publication, a simpler algorithm that lacks future pruning is presented and proven correct. Its performance is compared with future pruning. It is demonstrated, using examples, that neither approach is systematically better than the other. However, the simple algorithm has some attractive features. It never needs to re-construct pruned parts of the minimal coverability set. It automatically gives most of the advantage of future pruning, if the minimal coverability set is constructed in depth-first or most tokens first order, and if so-called history merging is applied. Some implementation aspects of minimal coverability set construction are also discussed. Some measurements are given to demonstrate the effect of construction order and other implementation aspects.
This paper proposes a vehicle reidentification (VRI) based automatic incident algorithm (AID) for freeway system under free flow condition. An enhanced vehicle featurematching technique is adopted in the VRI component...
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This paper proposes a vehicle reidentification (VRI) based automatic incident algorithm (AID) for freeway system under free flow condition. An enhanced vehicle featurematching technique is adopted in the VRI component of the proposed system. In this study, arrival time interval, which is estimated based on the historical database, is introduced into the VRI component to improve the matching accuracy and reduce the incident detection time. Also, a screening method, which is based on the ratios of the matching probabilities, is introduced to the VRI component to further reduce false alarm rate. The proposed AID algorithm is tested on a 3.6 km segment of a closed freeway system in Bangkok, Thailand. The results show that in terms of incident detection time, the proposed AID algorithm outperforms the traditional vehicle count approach.
The study of community detection algorithms in complex networks has been very active in the past several years. In this paper, a Hybrid Self-adaptive Community Detection Algorithm (HSCDA) based on modularity is put fo...
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The study of community detection algorithms in complex networks has been very active in the past several years. In this paper, a Hybrid Self-adaptive Community Detection Algorithm (HSCDA) based on modularity is put forward first. In HSCDA, three different crossover and two different mutation operators for community detection are designed and then combined to form a strategy pool, in which the strategies will be selected probabilistically based on statistical self-adaptive learning framework. Then, by adopting the best evolving strategy in HSCDA, a Multiobjective Community Detection Algorithm (MCDA) based on kernel k-means (KKM) and ratio cut (RC) objective functions is proposed which efficiently make use of recommendation of strategy by statistical self-adaptive learning framework, thus assisting the process of community detection. Experimental results on artificial and real networks show that the proposed algorithms achieve a better performance compared with similar state-of-the-art approaches.
A transformerless three-phase on-line uninterruptible power supply (UPS) is proposed. The proposed UPS is composed of a rectifier, an inverter and a battery charger/discharger. The rectifier regulates a DC-link voltag...
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A transformerless three-phase on-line uninterruptible power supply (UPS) is proposed. The proposed UPS is composed of a rectifier, an inverter and a battery charger/discharger. The rectifier regulates a DC-link voltage and performs power factor correction. On the other hand, the inverter provides a regulated sinusoidal output voltage and has the current-limiting capability for an impulsive load The battery charger/discharger reduces the number of battery and supplies the power demanded by the load in the event of the input power failure or abrupt decrease of the input voltage. Since both neutral lines of the input and output voltages are connected at the centre of the DC-link, the need for an isolation transformer is eliminated and the size, weight and cost of the system are significantly reduced. Additionally, new control algorithms of the rectifier, the charger/discharger and the inverter are proposed.
The world-in-miniature metaphor (WIM) allows users to select, manipulate, and navigate efficiently in virtual environments. In addition to the first-person perspective offered by typical virtual reality (VR) applicati...
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The world-in-miniature metaphor (WIM) allows users to select, manipulate, and navigate efficiently in virtual environments. In addition to the first-person perspective offered by typical virtual reality (VR) applications, the WIM offers a second dynamic viewpoint through a hand-held miniature copy of the environment. In this paper we explore different strategies to allow the user to interact with the miniature replica at multiple levels of scale, Unlike competing approaches, we support complex indoor environments by explicitly handling occlusion. We discuss algorithms for selecting the part of the scene to be included in the replica, and for providing a clear view of the region of interest. Key elements of our approach include an algorithm to recompute the active region from a subdivision of the scene into cells, and a view-dependent algorithm to cull occluding geometry. Our cutaway algorithm is based on a small set of slicing planes roughly oriented along the main occluding surfaces, along with depth-based revealing for nonplanar geometry. We present the results of a user study showing that our technique clearly outperforms competing approaches on spatial tasks performed in densely occluded scenes.
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