General information
Quaestor product leaflet

Quaestor is a knowledge based engineering framework to develop and use applications providing workflow, data and calculation management to streamline analysis, design and engineering processes.

  • It is a development framework to integrate model fragments and knowledge components (such as formula’s, programs, spreadsheets, database, etc.) with limited effort or knowledge about programming into a consistent knowledge based system;
  • It is a smart user environment for knowledge bases, providing workflow, data and calculation management assistance.
What makes Quaestor special:

  • every knowledge component can be used the moment it is saved in the knowledge base (“programming” and “use” can be very close);
  • easy configurable workflow through Taxonomy-Entity concept (full control over the amount and order of user information requests);
  • ability to use value ranges as input (for instance, enabling investigation of design space by means of parameter variation);
  • powerful document generation and software scripting (for instance, Word, Excel, Visio, Rhinoceros, MatLab, etc. can all be scripted and executed);
  • full traceability of all intermediate and end-results (for instance, the input and output of every external program is stored in the project file);
  • goal and input driven assembly of calculation methods and instant availability of “reasoning” functionality (Quaestor "knows" about dependencies through your implemented relations between knowledge. These dependencies are uses to search ways for solving your requested goal parameters);
  • computational model inversion within the knowledge base and with connected external programs (for instance, Quaestor can determine a necessary input based on a desired output);
The framework does not contain domain knowledge, use is not restricted to a specific domain. As a results Quaestor applications can be develop for any field of expertise. Over the years, MARIN has developed several knowledge based systems in the hydrodynamic domain. Therefore, Quaestor can be delivered in combination with knowledge bases containing hydrodynamic engineering tools.

Furthermore, Quaestor is highly scalable and can be used for very small applications up to very large development systems.

Please visit Workflow Solutions for more information on types of applications and our work on streamlining design and engineering processes. For more details on software sales click [here].

More insight...
Some more insight into a Quaestor knowledge based system follows below.

DeSIS ship design workflow DeSIS ship design workflow
What makes a knowledge based system
A Quaestor knowledge based system can be seperated into three parts:

  1. Quaestor:
    The software program installed on a PC containing all functionality to ease development and use of a knowledge based system (such as intrinsic functions, data & calucation management, etc.).
    Obviously modiffication to Quaestor can only be made by the Quaestor developers at MARIN;
  2. The knowledge base:
    A file containing all domain specific knowledge (such as relations between parameters, programs, data, etc.);
    Quaestor users are able to modify the knowledge base when they have a knowledge engineering license. Optinally a knowledge base can be password protected or even encrypted by a knowledge engineer;
  3. The project:
    A file that is related to a specific knowledge base containing all solutions created with the knowledge based system.
    Quaestor users are able to modify projects when they have a knowledge engineering or domain expert (DE) license. Again, optionally a project file can be password protected by another user;
The idea behind this approach is to seperate knowlegde from data, development from use, generic functionality from domain specific functionality. In this way you ensure flexibility, maintainability and scalibility for both simple and complex systems in both small and large user groups.

For more details on user rights, click here.
For more details on knowledge base protection, click here.

Developement: knowledge engineering
For developement, a knowledge engineer (a knowledge base developer) works in a knowledge base opened by Quaestor. This knowledge base is a fully "white box" system for the knowledge engineer.

Based on the correct rights (the correct user license and optionally a knowledge base password or encryption key), every relation can be added, used or modified. Moreover, every link between relations, constraints, parameters and (intermediate and end) results can be traced throught the Quaestor GUI. Quaestor also contains many intrinsic functions (for a list click here), attributes, constants and GUI guidance to assist with knowledge base development.

Please note that you do not necessarily have to be a software developer to develop knowledge bases. Knowledge base development requires good insight in your domain/topic and only basic affinity with programming which normally is part of any engineering education.

The main idea is that knowledge engineers can store computational model fragments in the knowledge base. These fragments consist of relationships, formulas or tools with their validity, static data, descriptions, optional illustrations, properties and parameters. Since the output of one model fragment can be input for another, all components together form an undirected network of 'rules'. This network controls the data and calculation management capabilities of the system.

A Quaestor knowledge network A Quaestor knowledge network
In addition, a Knowledge Engineer (KE) can create a Taxonomy of a process or product. This is the blue print (or DNA) of the process or product. In this way, the KE is able to use the workflow capabilities of the system. It enables the KE to have full control over the process or workflow during the analysis, design or engineering process without losing the power of the Quaestor model assembly capabilities.
All parameters, relations, connections to other programs etc. can be fully described in text, illustrations and hyperlinks to further background information. In this way by developing knowledge bases, you are managing all your knowledge on methods and processes used in your environment.

Quaestor applies a unique and advanced bi-directional chaining strategy of reasoning, computer algebra as well as network and relational database concepts. It offers a knowledge management environment and is able to invoke external executable programs, spreadsheets and databases.

Users always work in the project file that is started in combination with Quaestor and the knowledge base file. Therefore, you are never able to add or modified knowledge (relations etc.) but can only use the content of the knowledge base.

Inside a project you work with solutions. Solutions are created by requesting the knowledge based system to determine a goal. This goal can either be "configuring a ship" or "creating a report" or "calculating a value".

Depending on the type of knowledge base, the goal is determined by means of following the presented workflow and providing input and choices to requests made by the Quaestor reasoning system based on the alternatives found in the knowledge base. During the process of creating a solution the designer/engineer or user remains central. This person remains the "man in the loop" deciding about input to be given and choices to made.

Quaestor architecture Quaestor architecture
Whether you are able to make a new solution or to restart an existing solution in a project will depend on your user license. The Domain Expert has full user rights. An "End-user" license can only carry out very simple (and limited) actions.

Furthermore, depending on your personal settings and user rights, you can follow every link between (intermediate and end) results in solutions based on their relations and constraints in the knoweldge base. In other words, the knowledge based system can be a "white box" system for the user to.

For more details on user rights, click here.

Product website
Please go to Quaestor.org for the lastest information on Quaestor use and development.

The Quaestor 3 GUI nowadays starts with a Quaestor start page. This is a convenient way to have all the Quaestor and MARIN information at your fingertips.

Relevant papers and publications
(A complete overview of papers can be found under Publications)

Design of a new generation submarines
Bruijn, SWZ, 2009

Emergency Towing Vessel, Concepts for a New Centrury of Emergency Towing
Stroo, SWZ, 2009

[Q]COOL: A Knowledge based Cooling Water System Configurator
Blom, Hees, COMPIT, 2006

Combining a Knowledge System with Computer-Aided Design
Oers, Hees, COMPIT, 2006

Floating Windfarms for Shallow Offshore Sites
R.H.M. Huijsmans, R.H.M. van Hees, M., Henderson, A.R., Zaaijer, M.B., Bulder, B., Pierik, J., Snijders, E., Wijnants, G.H. and , ISOPE Conference, Toulon, 2004

Knowledge-based Computational Model Assembling
Hees, Summer Computer Simulation Conference, Montreal, 2003

Quaestor: Expert Governed Parametric Model Assembling
Martin Th. van Hees, PhD-thesis, Delft University of Technology, 1997

Quaestor is a Maritime Simulation & Software Group (MSG) framework.

For general information:
Maritime Simulation & Software Group
2, Haagsteeg
P.O. Box 28
6700 AA Wageningen
The Netherlands

Phone +31 317 49 32 37
Fax. +31 317 49 32 45
E-mail msg@marin.nl

Expert contacts:
Arno Bons MSc
Project Manager

Martin Th. van Hees PhD
Senior Software Architect Quaestor

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