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991.
This article aims at bridging the gap between traditional designs to discrete-event control problems and supervisory control theory of Ramadge and Wonham. We propose to implement supervisory control by extending the plant's finite state machine with Boolean variables, guard formulas and updating functions. Boolean variables are used to encode the supervisor's states, event observation is captured by a set of Boolean functions that update the value of variables, and control is introduced by guarding events with Boolean formulas. The framework developed in this work is fundamental in our ongoing research on communication between supervisors in a distributed discrete-event system. 相似文献
992.
993.
Optimization algorithms are studied for a class of semi-Markov control processes (SMCPs) with compact action set. Both the long-run average and discounted cost problems are considered. Formulas of performance potentials and optimality equations for SMCPs are derived. A policy iteration algorithm and a value iteration algorithm are proposed, which can lead to an optimal or suboptimal stationary policy in a finite number of iterations. The convergence of these algorithms is established, without the assumption of the corresponding iteration operator being a span-contraction. In addition, an online policy iteration optimization algorithm based on a single sample path is provided to escape ‘curse of dimensionality’. In the end, a numerical example is provided to illustrate the application of the algorithms. 相似文献
994.
Abstract Various “living” polymers were grafted onto C60 The number of arms of the so obtained “star” molecules can be controlled by stoechiometry and/or by varying the reactivity of the carbanion on the “living” chain against a double bond on the C60. Even the oxanion of “living” polyethylenoxide is able to add onto the reactive double bonds on C60. In some conditions, the carbanions present on these alkaline salts of grafted fullerenes becomes able to initiate anionic polymerization of vinyl monomers. Using “living” poly(phenylvinylsulfoxide) as a precursor polymer for PA, polyacetylene chains could be attached to the fullerene. 相似文献
995.
This paper proposes an integrated method for preventive maintenance and inventory control of a production line, composed of n machines (n?≥?1) without intermediate buffers. The machines are subject to failures and an age-dependent preventive maintenance policy is used. Approximate analytical results are proposed for the one machine case. Simulation software is used to model and simulate the behaviour of the production line of n machines under various maintenance and inventory control strategies. A methodology combining the simulation and genetic algorithms is proposed jointly to optimize maintenance and inventory control policies. Results are compared with the analytical solutions. 相似文献
996.
Fracturing maps over a granitic dome (Scaër granite, Brittany, France) have been extracted from the most widely available remotely-sensed data and from aerial photographs. Comparison of the different maps obtained allowed the classification of the mapping potential of the different raw and merged images as well as ranking their ability to point out geological features at different scales. Three different types of geological features were pinpointed: a coarse regional fracturing, kilometric plutonic domes and finer geological structures such as circular features within the granitic dome. The best means of revealing each of these three types of geological features, proved to be radar images, multi-spectral data and aerial photographs, respectively. The data providing the largest range of observation and the greatest amount of information on geological structures and soil types were the merged Landsat-TM and SPOT panchromatic images. 相似文献
997.
Scheduling problems concern the allocation of limited resources over time among both parallel and sequential activities. Load balancing has been adopted as an optimization criterion for several scheduling problems. However, in many practical situations, a load-balanced solution may not be feasible or attainable. To deal with this limitation, this paper presents a generic mathematical model of load distribution for resource allocation, called desired load distribution (DLD). The objective is to develop a DLD model for scheduling of unrelated parallel machines that can be used both in centralized resource management settings and in agent-based distributed scheduling systems. The paper describes the proposed DLD model in details, presents a dynamic programming based optimization algorithm for the proposed model, and then discusses its application to agent-based distributed scheduling. 相似文献
998.
Kiho Bae Kyung Sik Son Jun Woo Kim Suk Won Park Jihwan An Fritz B. Prinz Joon Hyung Shim 《International Journal of Hydrogen Energy》2014
This work elucidated the proton-incorporation mechanism in ALD YSZ1. Isotope 2H2O was used as an oxidant to trace proton incorporation. The ratio of ZrO2 to Y2O3 ALD cycles was varied from 1:1 to 5:1. TEM confirmed that the ALD YSZ films grew as fully crystallized columnar grains in the cubic ZrO2 phase. SIMS indicated that the Y3+ and 2H+ concentrations were linearly correlated, indicating yttria-deposition-induced proton incorporation. XPS confirmed an appreciable amount of Y(OH)3 proportional to the 2H+ content in the ALD YSZ, as was also detected by SIMS. Oxide ion vacancies created by the replacement of ZrO2 with relatively small amounts of Y2O3 provided additional vacancies for proton incorporation, resulting in steeper [2H+]/[Y3+] slopes. 相似文献
999.
Humivorous termites are dominant members of tropical rainforest soil communities. In the soil‐feeding subfamily Apicotermitinae (Termitidae), the enteric valve connecting the first section of the hindgut to the paunch often displays a complex sclerotized armature everted towards the lumen of the paunch. This structure is central in termite taxonomy but its function remains hypothetical. Here, we evaluate the potential of confocal laser scanning microscopy to provide detailed imaging of the valve of Anoplotermes parvus, by comparison with bright‐field microscopy and scanning electron microscopy. We detected a strong far‐red emission of the enteric valve armature that sharply contrasted with the surrounding tissues, providing a convenient method to highlight minute structural elements of the valve and its three‐dimensional structure. The method is easy to use and is applicable to standard archival material as demonstrated by images of enteric valves of four other Apicotermitinae species. It may represent a valuable asset for the study of termite enteric valves, for the purpose of taxonomy or functional morphology. 相似文献
1000.
Communication technologies have been hailed as having a potential to promote democracy and freedom, and this paper aims to examine these claims in a comparative, international context. Our analysis focuses on the mediating role of horizontal communication networks (i.e., telephone, mobile telephone and the Internet) in the relationship between culture and political development. Using cultural value indicators of the World Values Survey and the measures of communication technology development, this study tests the mediating path from culture to communication technologies and to political development. The results suggest that cultural values have a role in shaping the structural characteristics of horizontal networks such as accessibility and decentralization, and that these features of horizontal networks are positively related to institutional and effective democracy as well as to economic competitiveness of nations. 相似文献