Products/FAQ : OptQuest Fact Sheet
What is CSIM 19/OptQuest?
CSIM 19/OptQuest is a version of the OptQuest Callable Library (OCL), a product of OptTek Systems, which has been adapted to work with the CSIM 19 Simulation Engine. OptQuest is a simulation run supervisor. It makes repeated calls to a simulation model, searching for the "best" configuration of the system being modeled.
What Are the Benefits of Using CSIM19/OptQuest?
Systems designers and systems managers need to find the best possible configuration for their systems. The best configuration is typically the selection of components, schedules, software, and operating strategies which accomplish one of the following goals:
Deliver the best possible performance while staying within the specified cost constraints
Achieve the lowest configuration cost, while meeting the specified performance criteria.
One way of conducting the search for the best configuration is to create a simulation model of the system and then to use this model to evaluate different configurations. CSIM 19/OptQuest offers an efficient way of accomplishing this search for the best configuration.
In some cases, performance can be improved significantly, while incurring no or little additional costs, by implementing some simple changes, such as modifying manpower schedules or changing other operating procedures. In many cases, there are alternative components which deliver performance that is "good enough" to achieve a performance goal, but have much lower costs. Often, it is imperative that the system deliver the best possible performance, in order to avoid performance related penalties or other costs associated with less than optimal performance. OptQuest efficiently automates the search for the best configuration. CSIM 19 lets you build comprehensive and efficient simulation models. The combination lets you realize the benefits of finding the best configuration.
How Does CSIM19/OptQuest Work?
The analyst creates a CSIM 19 simulation model of a complex system. This model is written so that important components of the model (in particular those components which control important features of the system's operation) are supplied as inputs to the model. The analyst also "sets up" the optimization problem for OptQuest; in particular the analyst specifies an objective of the problem as well as limits on the configuration variables and additional requirements, which must be satisfied in order to have a feasible configuration.
During a run of the application, OptQuest supplies a "configuration" (a set of values of the input configuration variables). The model executes using this configuration and returns the value of the objective as well as the values of the additional requirements. OptQuest then evaluates these returned values, and, based on these values, presents another configuration to the model. This process continues automatically until the application either "gives up" and quits or until OptQuest has generated every feasible configuration. At any time, the application can query OptQuest to retrieve the "best configuration so far."
What are the Search Techniques used by OptQuest Callable Library?
The general technique is called Tabu Search. OptQuestCallable (OCL) uses Tabu Search, along with the metaheuristic, mathematical optimization, and neural network components of OptQuest to guide the search for best solutions to decision and planning problems of all types. The user-written application passes to OptQuest OCL an indication of the quality of each solution generated during the search, by calling an evaluator (such as an objective function) which can take any form. In some situations, the evaluator may simulate a complex system to determine its behavior based on a proposed configuration.
Where did OptQuest and OCL Come From?
OptQuest and OCL are from Optimization Technologies, Inc. (OptTek) in Boulder, CO. The primary developers of OptQuest are Professors Fred Glover, Jim Kelly and Manuel Laguna. OptTek and Mesquite Software have entered into an agreement which covers marketing, supporting and developing OptQuest for use with CSIM 19 simulation models.
Can I Use OptQuest with an Existing CSIM 19 Model?
Most certainly! The CSIM 19 model must be structured (or restructured) so that:
The model can be executed repetitively,
The important features of the configuration (the ones that will be adjusted as part of the study) are inputs to the model; in particular these need to be inputs and not compiled-in constants, and
The model returns the values of the objective and any requirements that must be met.
If a CSIM 19 model has to be modified to operate in this way, the changes required are usually minimal.
How Would I Use CSIM 19/OptQuest?
Many simulation models are used to develop the best possible configuration of a system. Before OptQuest, doing this with a CSIM 19 model usually entailed successive runs of the model, trying to find a configuration that is "good enough", to meet the cost-performance criteria for the system.
With OptQuest, this search for improving configurations is done automatically. The search techniques in OptQuest usually drive system configurations toward the optimal configuration in a very efficient manner. This approach, based on automatic searching, is usually more thorough and more efficient than the manual approach mentioned above.
You would use OptQuest to help find the best possible configuration for the system you are designing and/or evaluating.
Does CSIM 19/OptQuest Really Work?
There are some sample models available for examination on the www.mesquite.com web site. There are several articles and application studies on the www.optQuest.com web site which describe a variety of successful applications of OptQuest in many different problem domains.
What are the Advantages of Combining CSIM 19 and OptQuest?
OptQuest is an automatic search supervisor. It uses simulation models to find the best possible configuration of the system being analyzed. It turns out that with a faster simulation model, more evaluations can be conducted and leading to better configurations. In addition, the simulation model must accurately reflect the structure and operation of the real system.
CSIM 19 models are very efficient, executing with short elapsed times. In addition, CSIM 19 models are computer programs; as such, they can be constructed to accurately model the important features of almost any system, regardless of the nature and structure of that system.
By incorporating all of these features (efficient automatic searching, fast execution speeds for the model and accurate representation of the system), analysts can use CSIM 19/OptQuest to build "industrial strength" applications to find the best possible configuration of the system being analyzed. Finding the best possible configuration of a system can result in both significant reductions in system costs and significant improvements in system performance.
How Can I Obtain CSIM 19/OptQuest?
You can order CSIM 19/OptQuest from Mesquite Software, Inc. There are two kinds of licenses:
One for customers who already have a license for CSIM 19 and
One for customers who need to purchase the integrated CSIM 19/OptQuest package.
For pricing and availability, contact Mesquite Software:
Phone: (512) 338-9153
In the US: (800) 538-9153
Fax: (512) 338-4966