Propellant-powered actuator for gas generators

Hydrazine operated monopropellant generators are used for spacecraft rocket engines and propellant pressurization systems. Measured work output of monopropellant actuators compares favorably with output of squib-type actuators

Ferromagnetic-fluid logic devices

Logic element switches flows of low pressure process control fluid in fluidics assemblies. Device operates both electrically and fluidically and is controlled by passing permanent magnet or electromagnet over elements, thus providing proximity switching functions

Guidelines for Software Development for Decision Support Systems

One of the activities of the System and Decision Sciences Program is the collaboration with scientists and institutes from different countries and with other programs and projects at IIASA in the field of Methodology of Decision Analysis. The main results of these activities are the development of theory, methodology and software for Decision Support Systems. A considerable amount of experience and software has been accumulated for over ten years of this type of cooperation. However, the analysis of the results of software development activities indicates the need for setting and observing some specified Guidelines for Software Development. This Working Paper contains a first version of such Guidelines which is the result of discussions with software developers. The draft of this Working Paper has been distributed for comments to about hundred scientists involved in development of software for Decision Support Systems. Since no reservations for the proposed Guidelines have been communicated to the author, one can assume that there is a general agreement for setting these Guidelines as a working scheme for the development of software for Decision Support Systems within the cooperation with the System and Decision Sciences Program. Although the Guidelines are oriented for a specific type of software, most of them can and should be observed in the development of any kind of software

LP-DIT Data Interchange Tool for Linear Programming Problems (version 1.20)

The MPS format (and its various extensions) is the de facto standard for handling data of an LP problem. The MPS format is widely used despite of its well known disadvantages, simply because there is no other widely agreed way of handling LP problem data and solution. However, for any real-life application when a sequence of modified LP problems is solved, preparing data (and their modifications) using the MPS format is both inefficient and cumbersome. Therefore the need for an efficient alternative is widely recognized. It is hardly possible to propose an alternative that could be commonly accepted unless the alternative is efficient and easy to incorporate into existing software. Therefore instead of considering another format of data, one should rather agree on a set of data structures and functions that can be used in a way similar to usage of standard libraries. Restricting a specification to the data structures and functions makes it possible to hide internal data structures and implementations of functions. LP-DIT is an attempt to contribute to the creation of such an alternative. LP-DIT serves two purposes: First, to propose a data structure and declarations of functions that can easily provide efficient data processing commonly needed for interchange of LP problem data between different software modules. Second, to provide a public domain tool (fairly easy to implement and efficient to use) which allows for LP problem data interchange. In other words, LP-DIT provides an alternative for using the MPS format to access and modification of LP problem data. Additionally, LP-DIT provides efficient and flexible functions for a full definition (which includes information contained both in the NIPS format and in a specification files) of an LP problem, its modifications and solutions. The current version of LP-DIT is the result of several applications made for different problems (i.e. using different problem generators and LP solvers). However, it is still a prototype and therefore, criticism and suggestions will be appreciated

Selected Issues of Design and Implementation od Decision Support Systems

The paper presents selected issues related to design and implementation of model based Decision Support Systems (DSS). For over ten years the SDS Program has been involved in cooperation with various projects at IIASA and in collaborating research institutes. This cooperation has resulted in the development of many DSS, which in turn stimulated research on the theory and methodology of decision analysis. An overview of selected DDS developed within the cooperation with IIASA is presented. Different concepts of DSS are briefly discussed and one specific type of DSS, namely model based, aspiration-led DSS is characterized. Finally, selected problems of designing and implementation of a DSS are discussed in more detail. A short description of software packages developed within the cooperation with the MDA Project is provided. The paper also gives a short summary of recent activities of the Methodology of Decision Analysis Project and of the DSS software available from the MDA Project