Description:
Research, teaching & application of operations research.
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Considering correlation in stochastic programming
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In dealing with a production problem under demand uncertainty, I build a model in the traditional form of stochastic programming where the demand uncertainty is discretized into several scenarios, and are then all scenarios for all products are permuted to generate all possible combination scenarios between products. However, I think by doing so,... more »
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Boolean variables in Cplex.
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Hello , I have a array of variables Z[10] for example and i want them to be 0 or 1.( boolean) , I have declared it as follows : IloNumVarArray Z(env,M,0,1,ILOINT); However when i use env.out() to see what are the values of Z .... one or two or them read 1.11022e -016 .... which is zero but why is is... more »
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Filmproduction / Filmproduktion 2008/07
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Filmproduction Contracting ? / Har ni något gig åt oss…? Vi söker konsultuppdrag / konsultering inom filmproduktion. Vänligen Mr Roger K. Olsson Int: +46 (0) 705474830 keywords:, film, filmprodution, director, regisör, filminspelning, produktionsbolag, hollywood, international film, filmfoundation,... more »
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Regarding robust optimisation
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Dear all, I have a LP model here as follow: Min = .42*x1 + .56*x2 + .70*x3; S.t. x1 + x2 + x3 = 900; x1 <= 400 * y1; x2 <= 700 * y2; x3 <= 600 * y3; 30*x1 <= 12500; 40*x2 <= 20000; 50*x3 <=15000; .15*x1 + .2*x2 +.15*x3 >= 100; .2*x1 + .05*x2 + .2*x3 >= 100; .25*x1 + .15*x2+ .05*x3 >= 150; y1+y2+y3 = 2;... more »
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Query on PROC NLIN constraints
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Proc NLIN is used for non-linear regression... but say one parameter is constrained in terms of other. eg. if we put bounds as x <= y <=z , where both x and y are the parameters to be estimated.. in this case, many times the solution comes out to be x = y = z. But it should not happen that way and solving the same thing in matalb... more »
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Modeling time dependent arrival rates using gamma distribution
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Hello Everyone, I am modeling the patient arrival rates during a mass casualty event and as we all know, they are time dependent and not constant. I am trying to use gamma distribution to model the arrival process. I am aware that gamma distribution is characterized by two parameters namely the shape and the scale parameter. Now during a disaster... more »
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Excel grouping problem
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Hi I'm looking for a way to group a set of numbers in excel using a solver so that I can minimize the total number of groups while minimizing the difference between each number and the "group number". For example, lets say I have: a = 2.3 b= 3.5 c= 3.1 d=2.6 e=4.1 f=3.2 Now I want to create Group1 and Group2 so that each number a-f is in... more »
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MODI Method and complementary slackness
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Hello, my question is generally the same one, which was asked on this group some time ago: ------------------ I have a little problem understanding the MODI method for solving the transportation problem and I hope somebody can help me with it. The MODI method regards the dual problem to the transportation problem with variables... more »
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Inventory Model with Arena -> How to?
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Hi, I want to modell a simple inventory model: normally distributed Customer demand occurs over n periods -> order is fulfilled by onhand stock or safety stock with lead time zero and to given service degree - ...How can I model this? I need some sort of customer demand with satisfaction and an information flow to start production in order to... more »
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Indicator Constraints
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I need to impose the following constraints : over(i) = 1 --------> y(i) >= 1 over(i) = 0 --------> y(i) <= 0 under(i) = 1 ------> y(i) <= -1 under(i) = 0 -------> y(i) >= 0 over(i) , under(i) are binary variables. y(i) is a integer variable. Thanks Arush.
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