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5.3. CORMIX MIXING ZONE MODELDoneker et al. CORMIX is a rule-based expert system for analysis and modeling of discharge and water mixing conditions (Doneker 96). As a system, it illustrates well how expertise about a very complex problem can be captured and incorporated in a knowledge base on a computer using simple techniques. The lesson is fairly straightforward: the sophistication of the system is primarily a function of the expertise incorporated rather than the way it is captured and delivered. The system is based on knowledge on turbulent buoyant jet mixing applied to discharge problems and water condition evaluation. According to Doneker (Doneker 96), the Cornell Mixing Zone Expert System (CORMIX) consists of a series of software subsystems for the analysis, prediction, and design of aqueous discharges into watercourses, with emphasis on the geometry and dilution characteristics of the initial mixing zone, including the evaluation of regulatory requirements. On an overall level, CORMIX can be described as an analysis and prediction system. It can estimate the mixing behavior from a diverse menu of discharge types. Such discharge types encompass power plant cooling waters, brines from desalinization facilities, drilling rig-produced waters, municipal effluents, or thermal atmospheric plumes. CORMIX can also be applied across a broad range of discharge conditions ranging from estuaries, deep oceans, and swift shallow rivers, to stratified reservoirs. CORMIX will aid its users in determining the effects of both planned and nonintentional releases into a river or water area. Contamination, thermodynamic-related issues, and depositional problems can be addressed by means of the system. Doneker highlights the system features as follows:
CORMIX has three subsystems:
CORMIX runs on a DOS-based IBM-PC. It carries 2000 mixing rules. The rule-based part of the system is linked to a hydrodynamic simulation model. The CD-CORMIX is a recent extension to the CORMIX expert system. Like the former version, CD-CORMIX is a rule-based program containing rules for turbulent buoyant jet mixing behavior. The extension addresses in particular problems related to continuous dredge disposal and its associated water quality impacts. Both particle settling and plume behavior can be subjected to analysis by the system. CD-CORMIX takes into considerations five particle size fractions of discharge material and is able to predict the water quality, including the concentration and dimensions of the resultant disposal plume. Added up, the new extension will handle the following:
The CD-CORMIX is still under development at the time of writing. 5.4. STEWARDLehning et al. STEWARD (Support Technology for Environmental, Water and Agricultural Resource Decisions) is basically a hypertext system carrying a large body of textual knowledge related to multiple aspects of water resource management. It is available on the Internet (PennState 96). It is supported by a few active knowledge bases (Foster 94). The development of STEWARD was driven by the center's wish to develop software applications that solve water contamination problems and efficient water quality tests. Another aspect was the need to centralize written information, databases, and computer-based applications in water quality control processes in an electronic format and make them available to the public in an efficient manner. STEWARD incorporates several knowledge elements. These address issues such as general monitoring of water quality, water transport, contamination testing, treatment of contamination, environmental fate, health effects, and site management. This extensive expertise is controlled by the use of HTML-based hyper links on the WWW. Using an ordinary Web browser, STEWARD is accessed by means of "point-and-click" operations. The interaction with the knowledge units is not as simple as with the Whale Watcher Expert System described earlier. In contrast, the expertise that it contains seems overwhelming. Much of the information that the system can deliver is supported by multimedia such as images, sound, and animation. The active knowledge body follows the traditional rule-based IF-THEN schemata. They encompass both quantitative and qualitative problem-solving abilities. The rule base is linked to a set of databases. An example using the Control Systems Module highlights the scope of the system. Once selected, the module prompts you with the type of contaminant to be controlled. The user may select from a list of 20 alternatives, including ammonia, dissolved oxygen, dissolved nitrogen, organic matter, pesticide, sediment, etc. It will let the user put forward queries like "What is the leaching potential of the soil?", "What is the soil hydrologic group?", and "What is the nutrient application rate?" Each query is accompanied by a set of standard answers, which provide a state description of the site selected for control.
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