CONTENTS

Client Area Updates (User name and password required)

1. Xpress-MP release 2003E

Major enhancements have been made to the Xpress MIP performance. This has resulted in much shorter times to prove optimality on many MIP problems. [More]

2. ISMP sponsorship

Dash is one of the sponsors at the ISMP conference in Copenhagen next month. We would like to extend an invitation to those attending, that if you would like to see us for a chat, please feel free to visit our stand. [More]

3. Full User Meeting provisional program

The full provisional program of speakers at our October User Meeting in San Francisco, has now been published. If you book your place for the meeting before 15 August, you qualify to receive a free copy of Dash's book Applications of optimization with Xpress-MP. [More]

4. Shell Services International (Japan) Ltd and Dash Optimization enter into Technology Agreement

Shell Services International (Japan) Ltd (SSI Japan) and Dash Optimization (Dash) are pleased to announce that they have entered into an agreement whereby SSI Japan will use Xpress-MP optimization software as the basis for new value-added services, products and solutions to customers in Japan. [More]

5. AMPL translator

ampl2mos is a utility which enables you to translate AMPL format model and data files into the equivalent Mosel formats. The translator supports most AMPL statements and has been tested against a wide variety of AMPL models. Due to differences between the way Mosel and AMPL work, certain features, such as commands and scripts cannot be automatically translated. [More]

6. Stochastic beta

A number of Dash customers have expressed an interest in solving planning problems where there is uncertain information, for example in supply chain and electricity generation. Traditionally, Stochastic Programming has been a difficult to approach area due to the complexity of modeling uncertainty, particularly for multi-stage problems. The approach we have taken is to simplify the process of modeling stochastic problems by integrating SP modeling facilities and development tools within Xpress-Mosel and Xpress-IVE. [More]

7. New training dates

New training dates have been released for London, New York and San Francisco. Dates go up up November 2004. Booking form and synopsis details are available online. [More]

8. Applications of optimization with Xpress-MP: Production planning

This regular feature in our newsletter looks at a particular decision making application that can the treated by optimization, and show how it can be modeled in Xpress-Mosel. We hope that it will illustrate the range of problems that can be solved with Xpress-MP, and perhaps give you ideas that help with your particular applications.

In this part we look at a production planning application. A company produces bicycles, and wishes to plan production of one model for the next year per month. The production plan is to be based on the predicted monthly demand:

Jan 30000
Feb 15000
Mar 15000
Apr 25000
May 33000
Jun 40000
Jul 45000
Aug 45000
Sep 26000
Oct 14000
Nov 25000
Dec 30000

Up to 30,000 bicycles may be produced each month under normal conditions at a cost of EUR 130/bicycle. However, it is possible to increase capacity by up to 50% using overtime working - the cost of this is EUR 160 per bicycle.

Bicycles may be produced in one month and sold later on in which case a monthly storage cost of EUR 5 per bicycle is incurred. The initial stock is 2000.

This model can be formulated as an MIP model in Mosel, and the complete Mosel model can be seen here.

If you want to solve this problem, you can download the model and the associated data file and solve it in Xpress-IVE. An evaluation copy of Xpress-IVE can be obtained form our web site if you need it.

Extensions: The model can easily be extended to multi-period multi-site production planning. One weakness of the model as it currently stands is that stock is reduced to zero by the end of the planning period - there is no incentive to produce more bicycles than required. This may be prevented by imposing "horizon conditions" at the end of the planning period. Finally, the model makes no allowance for any uncertainty in demand. The model could be re-run each month once the demand has been realised for that month. A minimum (safety) stock level could be imposed to allow an unexpected increase. Or a stochastic programming approach could be used to incorporate the uncertainty directly in the model. A beta version of Xpress-SP will be released later in the year which will allow this last option to be implemented.
 

This example is drawn from the book, 'Applications of optimization with Xpress-MP', published by Dash Optimization in 2002. The book contains a complete description of the problem, the model formulation, the implementation with Xpress-Mosel, and solution with the Xpress-Optimizer, along with a further discussion of the wider context and related applications.

For more information on the book, or to purchase a copy on-line, please click here.

Client Area Updates (User name and password required)

The Dash Optimization's Client Area gives access to materials available to:

† Customers who have purchased software which is still under warranty;
† Customers under a current support contract;
† Customers who are currently evaluating our software.
† Temporary accounts are available to those who are considering purchasing our software.

Please e-mail privilege@dashoptimization.com if you believe you qualify for a username and password.

9. Updated Xpress-MP manuals

Up to date versions of the Xpress-MP manuals are now available to view and download from the Client Area of our website [More]