CHARACTERIZATION OF THE OPTIMAL SOLUTION OF THE HYDROTHERMAL DETERMINISTIC COORDINATION PROBLEM

Author(s):  
ROBERTO CANALES-RUIZ ◽  
MANUEL RUIZ-CASILLAS
2014 ◽  
Vol 20 (4) ◽  
pp. 471-489
Author(s):  
Miguel Aguilera ◽  
Manuel G. Bedia ◽  
Francisco Seron ◽  
Xabier E. Barandiaran

Intermittency is ubiquitous in animal behavior. We depict a coordination problem that is part of the more general structure of intermittent adaptation: the adjustment-deployment dilemma. It captures the intricate compromise between the time spent in adjusting a response and the time used to deploy it: The adjustment process improves fitness with time, but during deployment fitness of the solution decays as environmental conditions change. We provide a formal characterization of the dilemma, and solve it using computational methods. We find that the optimal solution always results in a high intermittency between adjustment and deployment around a non-maximal fitness value. Furthermore we show that this non-maximal fitness value is directly determined by the ratio between the exponential coefficient of the fitness increase during adjustment and that of its decay coefficient during deployment. We compare the model results with experimental data obtained from observation and measurement of intermittent behavior in animals. Among other phenomena, the model is able to predict the uneven distribution of average duration of search and motion phases found among various species such as fishes, birds, and lizards. Despite the complexity of the problem, it can be shown to be solved by relatively simple mechanisms. We find that a model of a single continuous-time recurrent neuron, with the same parametric configuration, is capable of solving the dilemma for a wide set of conditions. We finally hypothesize that many of the different patterns of intermittent behavior found in nature might respond to optimal solutions of complexified versions of the adjustment-deployment dilemma under different constraints.


Author(s):  
Omar Besbes ◽  
Francisco Castro ◽  
Ilan Lobel

We consider the pricing problem faced by a revenue-maximizing platform matching price-sensitive customers to flexible supply units within a geographic area. This can be interpreted as the problem faced in the short term by a ride-hailing platform. We propose a two-dimensional framework in which a platform selects prices for different locations and drivers respond by choosing where to relocate, in equilibrium, based on prices, travel costs, and driver congestion levels. The platform’s problem is an infinite-dimensional optimization problem with equilibrium constraints. We elucidate structural properties of supply equilibria and the corresponding utilities that emerge and establish a form of spatial decomposition, which allows us to localize the analysis to regions of movement. In turn, uncovering an appropriate knapsack structure to the platform’s problem, we establish a crisp local characterization of the optimal prices and the corresponding supply response. In the optimal solution, the platform applies different treatments to different locations. In some locations, prices are set so that supply and demand are perfectly matched; overcongestion is induced in other locations, and some less profitable locations are indirectly priced out. To obtain insights on the global structure of an optimal solution, we derive in quasi-closed form the optimal solution for a family of models characterized by a demand shock. The optimal solution, although better balancing supply and demand around the shock, quite interestingly also ends up inducing movement away from it. This paper was accepted by David Simchi-Levi, optimization.


2013 ◽  
Vol 760-762 ◽  
pp. 1892-1895
Author(s):  
Xi Hu Zhi ◽  
Ai Di Zhi

For streaming media proxy server systems which are geographically far apart, distributed streaming media proxy server clusters can be a good solution to reduce upward bandwidth consumption, shorten access distance, and improve service capacity; the key is to solve the coordination problem among the proxy servers. The decision problem of the user request dispatch actually belongs to NP-complete. This article proposes an online coordination algorithm for the distributed storage streaming media proxy servers, and discusses the relative deviation of the approximate solution from the optimal solution, to serve as a reference to the specific applications of clustered streaming media proxy servers.


In modern power system, protective relays are playing a vital role for protection of the whole system. The efficiency and reliability of whole protection system depends upon the combined and coordinated operation of protective devices such as relays, circuit breakers etc. Moreover, both types of relays viz., primary and backup relays have been used for smooth and reliable operation of the power system from years. A primary directional over current relay (DOCR) is setup for the fast response of any faulty condition. If it fails, then backup relay perform the same task after some time gap. Three different setting such as plug-setting multiplier (PSM), pickup current settings and time multiplier setting (TMS) are required of performing the operation. In this paper, three very popular swarm based meta-heuristic such as particle swarm optimization (PSO), artificial bee colony (ABC) and a recent hybridization of both, i.e., hybrid ABC-PSO have been implemented for the calculation of optimal coordination problem. This coordination problem is treated for continuous settings optimization for TMS and pickup current. An IEEE 8 bus system without grid has been opted for validation of the results. It is evident from the study that the hybrid ABC-PSO based proves to generate optimal solution providing better convergence rate as compared to individual PSO and ABC algorithm.


Author(s):  
Atour Taghipour

Companies are dependent on the resources and information of other members of the supply chains. To manage their resources, companies use coordination mechanisms. Despite the inter-dependency between logistics actors, they are independent units with conflicting objectives. These two characteristics can increase the complexity of planning in logistics networks. According to the literature of supply chain management, some mechanisms largely use the information shared by members to achieve an optimal solution and some others are based on minimum level of information sharing. This chapter addresses the coordination problem in a logistics networks with more than two partners, while the information is in a private element that is not exchanged with other partners.


2012 ◽  
Vol 2012 ◽  
pp. 1-21 ◽  
Author(s):  
Yuli Zhang ◽  
Shiji Song ◽  
Cheng Wu ◽  
Wenjun Yin

The stochastic uncapacitated lot-sizing problems with incremental quantity discount have been studied in this paper. First, a multistage stochastic mixed integer model is established by the scenario analysis approach and an equivalent reformulation is obtained through proper relaxation under the decreasing unit order price assumption. The proposed reformulation allows us to extend the production-path property to this framework, and furthermore we provide a more accurate characterization of the optimal solution. Then, a backward dynamic programming algorithm is developed to obtain the optimal solution and considering its exponential computation complexity in term of time stages, we design a new rolling horizon heuristic based on the proposed property. Comparisons with the commercial solver CPLEX and other heuristics indicate better performance of our proposed algorithms in both quality of solution and run time.


2015 ◽  
Vol 569 ◽  
pp. 24-42 ◽  
Author(s):  
Prosenjit Bose ◽  
Jean-Lou De Carufel ◽  
Stephane Durocher

Filomat ◽  
2017 ◽  
Vol 31 (3) ◽  
pp. 529-541 ◽  
Author(s):  
Tarek Emama

In this paper, we interest with deriving the sufficient and necessary conditions for optimal solution of special classes of Programming. These classes involve generalized E-[0,1] convex functions. Characterization of efficient solutions for E-[0,1] convex multi-objective Programming are obtained. Finally, sufficient and necessary conditions for a feasible solution to be an efficient or properly efficient solution are derived.


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