Cooper School – A specialist science school

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Some of the benefits that specialist science status has brought to the Cooper School and our stakeholders? Cooper School – A specialist science school
  • wider skills course
  • wider school community
  • special projects for pupils
  • recent survey amongst primary colleagues
  • specialist science school
  • bicester community
  • primary pupils
  • science
  • students
Published : Tuesday, March 27, 2012
Reading/s : 11
Origin : gams.com
Number of pages: 21
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GAMS
Transportation Model
Michael Bussieck mbussieck@gams.com
Lutz Westermann lwestermann@gams.com
GAMS Development Corporation
www.gams.com
GAMS Software GmbH
www.gams.de
INFORMS 2009 San DiegoWhat is a Model?
• Mathematical Programming (MP) Model
– List of Equations
• Collection of several intertwined MP Models
– Data Preparation
– Data Calibration
– “Solution” Module (e.g. sequential, parallel, loop)
– Report Module
2A Transportation Model
22.5
New York
325
600
San Diego
11.4
1.8
Topeka
275
2222.5
350
1..88
Seattle
11.7
Chicago
300
Minimize Transportation cost
subject to Demand satisfaction at markets
Supply constraints
3Mathematical Algebra
4GAMS Algebra
5A few Word about GAMS Syntax
• Symbols:
– Sets
– Parameters
– Variables
– EEquatioonns
– MModels
– ASCII Output Files
• Statements
– Declarations
– Data Assignments
– Equation Definition
– Programming Flow Control
– Option statement
6Demo! Transportation Model
7Modifications to the transport model
Put
Utilities
MIIP
GGDX
Utilities
LP MINLP
Convert
NLP
Spread-
sheet
8Types of Variables
• Continuous Variables
– Free/Positive/Negative
– Lower and/or upper bound
• Binnary Varriiables
– Either 0 or 1
• Integer Variables
– Any integer number
• Semicont/Semiint Variables
– 0 or above a given minimum
• Special Ordered Set Variables (SOS1, SOS2)
9Binary Variables
• Powerful Tool to model yes/no decisions
• Models with discrete variables (MIP)
– Solved using Branch-and-Cut algorithms (lots of LPs)
– TTheorettiically diiffficult prroblem clclass
– Practical:
• mixed bag
• Art of Modeling
• Example: Minimum Shipment
– Ship at least 100 tons or don’t ship
10

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