Modeling,analysis and performance evaluation for fault diagnosis and Fault Tolerant Control in bottle-filling plant modeled using Hybrid Petri nets

In this paper, an approach to achieve fault diagnosis and Fault Tolerant Control in a typical bottle-filling plant using event based techniques is discussed. For this purpose, the plant is modeled using Hybrid Petri nets which enable study and analysis with regard to the working of the plant. Once effective modeling is done based on two different case studies considered, new algorithms are proposed to achieve fault diagnosis and Fault Tolerant Control on the models developed. Finally, performance measures with regard to the models proposed are evaluated to check the correctness of the models developed. Both analytical and numerical results are obtained which are highly useful to understand plant behavior.     

On the core of cost-revenue games: Minimum cost spanning tree games with revenues

In this paper, we analyze cost sharing problems arising from a general service by explicitly taking into account the generated revenues. To this cost-revenue sharing problem, we associate a cooperative game with transferable utility, called cost-revenue game. By considering cooperation among the agents using the general service, the value of a coalition is defined as the maximum net revenues that the coalition may obtain by means of cooperation. As a result, a coalition may profit from not allowing all its members to get the service that generates the revenues. We focus on the study of the core of cost-revenue games. Under the assumption that cooperation among the members of the grand coalition grants the use of the service under consideration to all its members, it is shown that a cost-revenue game has a nonempty core for any vector of revenues if, and only if, the dual game of the cost game has a large core. Using this result, we investigate minimum cost spanning tree games with revenues. We show that if every connection cost can take only two values (low or high cost), then, the corresponding minimum cost spanning tree game with revenues has a nonempty core. Furthermore, we provide an example of a minimum cost spanning tree game with revenues with an empty core where every connection cost can take only one of three values (low, medium, or high cost).     

Tracking and controlling unstable steady states of dynamical systems

An adaptive controller for stabilization of unknown unstable steady states (spirals, nodes and saddles) of nonlinear dynamical systems is considered and its robustness under the changes of the location of the fixed point in the phase space is demonstrated. An analog electronic controller, based on a low-pass filter technique, is described. It can be easily switched between a stable and an unstable mode of operation for stabilizing either spirals/nodes or saddles, respectively. Numerical and experimental results for two autonomous systems, the damped Duffing–Holmes oscillator and the chaotic Lorenz system, are presented.     

Dichotomy and trichotomy of difference equations

Dedicated to Professor Gerry Ladas on his sixtieth birthday in acknowledgement of his leading role of difference equations. We extend the notions of dichotomy and trichotomy to nonlinear ordinary difference equations. This is accomplished by using two completely different approaches. In the first approach we use a notion, independent of the nature of our difference equation, called tracking. In the second approach we introduce a discrete analogue of dichotomy and trichotomy in variation.     

A bivariate mixed policy for a simple repairable system based on preventive repair and failure repair

In this paper, a simple repairable system (i.e. a one-component repairable system with one repairman) with preventive repair and failure repair is studied. Assume that the preventive repair is adopted before the system fails, when the system reliability drops to an undetermined constant R  , the work will be interrupted and the preventive repair is executed at once. And assume that the preventive repair of the system is “as good as new” while the failure repair of the system is not, and the deterioration of the system is stochastic. Under these assumptions, by using geometric process, we present a bivariate mixed policy (R,N)$(R\text{,}N)$, respectively based on a scale of the system reliability and the failure-number of the system. Our aim is to determine an optimal mixed policy (R,N)^∗$(R\text{,}N{)}^{\ast }$ such that the long-run average cost per unit time (i.e. the average cost rate) is minimized. The explicit expression of the average cost rate is derived, and the corresponding optimal mixed policy can be determined analytically or numerically. Finally, a numerical example is given where the working time of the system yields a Weibull distribution. Some comparisons with a certain existing policy are also discussed by numerical methods.     

Optimal corrective maintenance contract planning for aging multi‐state system

This paper considers an aging multi‐state system, where the system failure rate varies with time. After any failure, maintenance is performed by an external repair team. Repair rate and cost of each repair are determined by a corresponding corrective maintenance contract with a repair team. The service market can provide different kinds of maintenance contracts to the system owner, which also can be changed after each specified time period. The owner of the system would like to determine a series of repair contracts during the system life cycle in order to minimize the total expected cost while satisfying the system availability. Operating cost, repair cost and penalty cost for system failures should be taken into account. The paper proposes a method for determining such optimal series of maintenance contracts. The method is based on the piecewise constant approximation for an increasing failure rate function in order to assess lower and upper bounds of the total expected cost and system availability by using Markov models. The genetic algorithm is used as the optimization technique. Numerical example is presented to illustrate the approach. Copyright © 2009 John Wiley & Sons, Ltd.     

数量折扣契约下基于成本分担的供应链突发事件协调应对

突发事件会增加供应链成本,如何进行成本分担是决定供应链能否协调应对突发事件的重要因素.用参数分别描述市场需求剧增时增加的生产成本和市场需求剧减时发生的多余产品处理成本,在数量折扣契约基础上,研究突发事件发生后制造商的最优批发价格和零售商的最优订货量,分析其影响因素比较突发事件发生前后包括市场剧增与市场剧减两种情况下的差异,并给出了数值算例.结果表明,成本分担系数和市场需求分布及其变化都会影响最优批发价格和最优订货量,只要根据市场需求变化相应调整契约参数并合理分担由突发事件增加的成本,通过数量折扣契约供应链就能够协调应对突发事件.     

Analysis of the mean squared derivative cost function

In this paper, we investigate the mean squared derivative cost functions that arise in various applications such as in motor control, biometrics and optimal transport theory. We provide qualitative properties, explicit analytical formulas and computational algorithms for the cost functions. We also perform numerical simulations to illustrate the analytical results. In addition, as a by‐product of our analysis, we obtain an explicit formula for the inverse of a Wronskian matrix that is of independent interest in linear algebra and differential equations theory. Copyright © 2017 John Wiley & Sons, Ltd.     

Thermosensitive and control release behavior of poly(N-isopropylacrylamide-co-acrylic acid)/nano-Fe3O4 magnetic composite latex particle that is synthesized by a novel method

In this study, a novel method was used to synthesize the poly(N-isopropylacrylamide-co-acrylic acid)/Fe₃O₄ (poly(NIPAAm-AA)/Fe₃O₄) magnetic composite latex. The crosslinked poly(NIPAAm-AA) polymer latex particles were first synthesized by the method of soapless emulsion polymerization, then Fe²⁺ and Fe³⁺ ions were introduced to bond with the -COOH groups of AA segments in poly(NIPAAm-AA) polymer latex particles. Further by a reaction with NH₄OH, Fe₃O₄ nanoparticles were generated in situ. The concentrations of acrylic acid (AA), crosslinking agent (N,N′-methylene bisacrylamide (MBA)), and Fe₃O₄ nanoparticles were important factors to influence the morphology and lower critical solution temperature (LCST) of poly(NIPAAm-AA)/Fe₃O₄ magnetic composite latex particles. The poly(NIPAAm-AA)/Fe₃O₄ latex particles were used as a thermosensitive drug carrier to load caffeine. The control release of caffeine was studies. Morphology-based schematic models were proposed to explain the control release behavior of the composite particles with different compositions. Moreover, the protein (albumin, acetylated from bovine serum (BSA)) was bound on the surface of poly(NIPAAm-AA)/Fe₃O₄ composite latex particles. The effects of AA, crosslinking agent and Fe₃O₄ contents on the amount of BSA binding were investigated at different temperatures and pH values. The composition-morphology-BSA conjugation relationship was established.     

天然高分子药物微球载体材料的研究进展

综述了国内外在天然高分子药物微球载体材料研究及应用中的进展状况,主要从天然高分子药物微球载体材料的分类、微球的制备方法及特点、载药微球的给药途径和应用等进行概括,并对目前所存在的问题进行了描述。