Dear GAMS-Users,
I have a model that calculates the cost-minimal output of different machines. The temporal resolution is 8760 hours (= 1 year). One of the machines can only produce 4 hours a day. I don´t know how to implement this restriction into the model. Can anybody help me?
My idea was to use the binary variable ON (t) which describes whether the machine is online (=1) or offline (=0). The sum of this variable over one day has to be lower than 4 (hours):
(Set t /1*8760/)
The problem is, that I do not know how to sum over 24 hours. I used the subset t_sub (t,tt) = YES$((ord(tt) gt ord(t)-24) and (ord(tt) lt ord(t))). But it didn´t work.
Furthermore I don´t know how to express the fact that the sum should only be built if t = {1-24; 25- 48; 49 – 72; …}.
Please, can anybody help me?
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Dear Anne,
Attached please find a possible solution to your question. I hope it helps you.
Cheers,
Pedro
On Tue, Jun 17, 2014 at 2:52 PM, Anne wrote:
Dear GAMS-Users,
I have a model that calculates the cost-minimal output of different machines. The temporal resolution is 8760 hours (= 1 year). One of the machines can only produce 4 hours a day. I don´t know how to implement this restriction into the model. Can anybody help me?
My idea was to use the binary variable ON (t) which describes whether the machine is online (=1) or offline (=0). The sum of this variable over one day has to be lower than 4 (hours):
(Set t /1*8760/)
The problem is, that I do not know how to sum over 24 hours. I used the subset t_sub (t,tt) = YES$((ord(tt) gt ord(t)-24) and (ord(tt) lt ord(t))). But it didn´t work.
Furthermore I don´t know how to express the fact that the sum should only be built if t = {1-24; 25- 48; 49 – 72; …}.
Please, can anybody help me?
–
Example.gms (232 Bytes)
Hi,
Can you be more clear. you are saying that “One of the machines can only produce 4 hours a day” and then you are defining a binary variable and forcing the summation of the variable be less than 4. In my idea it is not justifiable.Working 4 hours means you are talking about time length that is continuous, binary variable is saying that, this machine was online 4 times during a day, but for how long???
That is what I understood from your problem, you van be more clear, so people here can help you to implement it in GAMS.
(although I think that this type of questions can be solved by better modeling, they are not directly related to GAMS tricks)
Best,
On Tue, Jun 17, 2014 at 9:52 AM, Anne wrote:
Dear GAMS-Users,
I have a model that calculates the cost-minimal output of different machines. The temporal resolution is 8760 hours (= 1 year). One of the machines can only produce 4 hours a day. I don´t know how to implement this restriction into the model. Can anybody help me?
My idea was to use the binary variable ON (t) which describes whether the machine is online (=1) or offline (=0). The sum of this variable over one day has to be lower than 4 (hours):
(Set t /1*8760/)
The problem is, that I do not know how to sum over 24 hours. I used the subset t_sub (t,tt) = YES$((ord(tt) gt ord(t)-24) and (ord(tt) lt ord(t))). But it didn´t work.
Furthermore I don´t know how to express the fact that the sum should only be built if t = {1-24; 25- 48; 49 – 72; …}.
Please, can anybody help me?
Babak Saleck Pay
Ph.D Student of Systems Modeling and Analysis
Department of Statistical Sciences and Operations Research
Virginia Commonwealth University
4156 Grace Harris Hall
1015 Floyd Ave.
Richmond, VA
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Dear Pedro,
thank you very much! 
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