Decision support systems

1. Decision support systems Вонр. проф. д-р Александар Маркоски Технички факултет – Битола 2008 год. Enviromatics 2008 - Decision support systems

2. Introduction • The investigations of environmental systems using mathematical simulationmodels allow statements for single important state variables while the controland management of environmental systems implies situations of decision makingwhich are characterised by multiple states, concurrent environmental goalfunctions and also by different evaluation scales and appreciations. Analysingenvironmental systems two control problems arises: • 1. Theoretical analysis, mathematical description and simulation of the changingenvironmental system behaviour. • 2. Elaboration of optimal control methods to realise active, goal oriented operationsreferred to the state and the behaviour of environmental systems. Enviromatics 2008 - Decision support systems

3. The first statement covers both the biocoenotic-structural and functional analysisof an environmental system and the modelling procedures used to predictchanges of environmental states. • The second statement is directed to the useof environmental systems by man and to environmental management and protection.Operating scales and environmental goals are defined by the bioticcomponents of environmental systems and by anthropogenic activities relatedto environmental management. Enviromatics 2008 - Decision support systems

4. Role of decision making process • Decision making is one of the main concepts to manage environmental systems. • The decision making process itself is characterised by choiceof one objective allowable kind of action related to a subjective valuated compromiseon partly satisfaction of the concurrent and conflicting environmentalgoals. • Optimisation models of environmental management mainly deal withsome form of cost minimisation designed to meet environmental quality and/orecological standards. Decisions are based on scenarios resulting from simulation models. • The individual weighting of the goal functions often depends fromtheir actually reachable system states. In search of all possible alternatives forcontrolling a dynamic system by restricting standards and socio-economic goalsthe use of a computer will be very helpful. Enviromatics 2008 - Decision support systems

5. The application of optimality principles to environmental systems is burdenedwith difficulties of fundamental nature. In the most cases, environmental systemanalysis is essentially a conflict analysis characterised by socio-economical andenvironmental value judgements. • The regulations of environmental systemevaluation are open to the methods of environmental law. This implies that amulti-related environmental process or system will always be understood as asearch for acceptable compromise solutions which requires an adequateevaluation methodology. • Multiple-criteria decision making techniques aim atproviding such a set of tools. Pareto-optimisation technique seems to be anadequate method to evaluate multi-goal functions of ecosystems. Enviromatics 2008 - Decision support systems

6. Multiple contradictory goals require decisions which are influenced by the dynamiccharacteristics of system compartments and their interrelationships, bythe kind of anthropogenic actions onto the aquatic ecosystem to be managed. • For this reason, water quality simulation models proved to be an indispensableassessment tool. • The management procedure involves sampling of data, selection of appropriate and validated simulation models and, finally, decision analysisas well as visualisation of results by GIS. Enviromatics 2008 - Decision support systems

7. Environmental management strategies • Environmental management is a very difficult and complex task. It requiresmathematical models not only for different time horizons but also for differentmanagement strategies. Simulation models allow a process control related tospecial goals of ecosystem management. • Most often the goal is a suitable controlscheme which presents a compromise between the available budget forprevention measures and an acceptable environmental quality. Therefore, environmentalmanagement strategies deal mainly with some form of operationalcost minimisation to meet environmental quality and ecological standards.Then, management decisions can be made by ranking of different scenariosresulting from simulation models. Enviromatics 2008 - Decision support systems

8. Computer-aided decision making process • The computer-aided decision making process can be divided into three steps.Two of them are subjective parts and one is an objective part of the decisionmaking process: • 1. Formulation of the decision problemIn this subjective part the decision variables and the contradictory goal functionalare defined. • 2. Computation of proposals for decision making.In this objective part of decision making a set of efficient alternatives will begenerated by multi-objective optimisation. The dominant alternatives are selectedand stored in the result domain. • 3. Actual decision making process.This subjective part of the decision making process covers the computeraidedselection of a compromise by individual weighting of the goal functionsby the decision maker. Enviromatics 2008 - Decision support systems

9. Three main requirements • Solving a decision problem three requirements have to be fulfilled: 1. Each solution of the decision problem is an efficient alternative (problem ofvalidity). 2. Each efficient alternative may be a solution of the optimisation procedure(problem of non-discrimination). 3. A solution of the decision problem is an efficient alternative, if it is existent(problem of identification). Enviromatics 2008 - Decision support systems

10. MADM and MODM • Another distinction of decision making problems can be made by multiple attributedecision making (MADM) or multiple objective decision making (MODM). • Inthe first case the alternatives can be explicitly evaluated by discrete values ofthe goal functions. • In the latter case the evaluation of alternatives is implicitlygiven by a functional and can change continuously in the domain of admissiblesolutions. • In such cases an important feedback between optimisation and modellingprocedures arises. Enviromatics 2008 - Decision support systems

11. 4 phases in multi-criteria decision process • A multi-criteria decision making process is given by four different phases. Duringthe first phase (search phase) a system will be analysed for changes in thestructure and the function. If the results of analysis are positive then one ormore decision making problems arise as a result from this first phase. • The second phase (modelling phase) is characterised by formulations of thegoal functions, by the directions of alternatives, by the modelling process andby the imbedding procedure of the simulation model into the optimisation procedure. Enviromatics 2008 - Decision support systems

12. The third phase (selection phase) is represented by choosing one alternativeof action of the set of all alternatives. This special alternative has to be implementedinto the system under consideration. • The fourth phase is characterised by the decision making process. The decisionmaking problem is represented by a set of alternatives which contributeto reach the different goals. For a given decision problem the set of allowablealternatives is defined by external (real) conditions. Enviromatics 2008 - Decision support systems

13. Decision support for environmental management means that a final state canbe reached by different ways of action starting from an initial state. The finalstate is described by any number of conflicting criteria. A decision of an individualmeans then a selection of one (subjective preferred) vectorial evaluated alternativeof action of a set of all objective allowable alternatives to reach thefinal state. Enviromatics 2008 - Decision support systems

14. Decision supportsystems classification • The decision making process is mostly based on interactive decision supportsystems (DSS) with hierarchical structures. The hierarchy is given by differentworking levels: Preparation level, simulation level, testing level and optimisationlevel. • DSS can be classified by simple software tools (e.g. data bases), by expertsystems and knowledge based systems (recognition of special environmentalsituations) and by model based DSS. • From the last classification typethe decision maker gets support by using of vector optimisation procedures orby multicriterial selection procedures to generate and/or to select alternativeways of action. Enviromatics 2008 - Decision support systems

15. Four main components of DSS • DSS consist of four main components: 1. Component of communication (communication between the DSS and an user(e.g. decision maker)). 2. Component of model and/or knowledge base (formulation of the actual decisionproblem). 3. Component of problem solving (solving procedures of vector optimisationproblems). 4. Component of visualisation (use of GIS). Enviromatics 2008 - Decision support systems

16. The search process Enviromatics 2008 - Decision support systems

17. Enviromatics 2008 - Decision support systems

18. Environmental Decision Support System Enviromatics 2008 - Decision support systems