Person:

Georgakakos, Aristidis P.

Permanent Link

https://hdl.handle.net/1853/71284

Associated Organization(s)

Organizational Unit

School of Civil and Environmental Engineering

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Publication Search Results

Now showing 1 - 10 of 10

Nile River basin impacts to climate and anthropogenic

(Georgia Institute of Technology, 1999) Georgakakos, Aristidis P.
Information systems for water resources monitoring and planning in the Lake Victoria Region

(Georgia Institute of Technology, 1999) Georgakakos, Konstantine P. ; Yao, Huaming ; Brumbelow, James Kelly ; Bourne, Stephen ; De Marchi, Carlo ; Mullusky, Mary ; Artan, Guleid A. ; Sperfslage, Jason A. ; Georgakakos, Aristidis P.
A Review of Fish Ecology Models and an Approach for Integrated Reservoir and Ecological Management

(Georgia Institute of Technology, 1997-03) Brumbelow, Kelly ; Georgakakos, Aristidis P.

Many species of fish have suffered detrimental impacts due to the construction and operation of reservoirs. Life-scientists have utilized three basic methods to attempt to include the needs of riverine ecology in the formulation of reservoir operation policies. (1) Beginning in the 1970's, discharge-based methods used heuristics to determine minimum allowable streamfiows to protect riverine life. (2) Habitat-based models were developed after the shortcomings of minimum allowable streamflow recommendations were realized and as greater knowledge of fish biology and ecology was gained. These models used hydraulic modeling and species- and lifestage-specific habitat preferences to determine quantity and quality of habitat as a function of streamflow. (3) Individual-based models have emerged in the 1990's as further understanding of fish life-processes has accumulated these models track the daily actions and movements of individual organisms. The State of Georgia currently uses a variety of discharge-based methods to determine minimum allowable strearnflows. The opportunity now exists to utilize many new technologies to integrate ecological and other "traditional" objectives in a real-time, operational decision support system. The principal technologies to be exploited include the ELQG algorithm individual-based models, computational fluid dynamics, and geographic information systems.
Water Resources Management: Challenges and Opportunities

(Georgia Institute of Technology, 1997-03) Georgakakos, Aristidis P.
A Control Model for Hydropower Systems Analysis and Operation

(Georgia Institute of Technology, 1995-04) Georgakakos, Aristidis P. ; Yao, Huaming ; Yu, Yongqing

In North America, hydropower provides a significant portion of the electrical capacity, ranging from about 60 percent in Canada, to more than 30 percent in Mexico, to about 13 percent in the U.S. (North America Hydroelectric Research and Development Forum, 1992). Among the attractive features of hydropower is that it is renewable, clean, efficient, economical., and domestically produced. In the U.S., the amount of hydroelectric production is equivalent to nearly 500 million barrels of oil annually, which, at today's oil prices, have a value of $9 billion. In addition to meeting electricity demands, hydropower facilities play a critical role in water management, helping to provide flood control and water for irrigation, municipal and industrial uses, navigation, recreation, and fish and wildlife preservation. Improving the way projects are operated is a top research need. It is worth noting that a 1 percent increase in the efficiency of existing hydro plants in the U.S. would provide an additional 3 billion kilowatt-hours of electricity annually, saving the equivalent of 1.4 million tons of coal or 4.9 million barrels of oil (North American Hydroelectric Research and Development Forum, 1992). The primary motivations for this research work are (1) to demonstrate that modem optimization methods can effectively optimize the utilization of hydropower facilities and (2) compare the relative performance of optimization and the more traditional simulation models. In this article, we take up the first task and describe the problems addressed, the models developed, and the results obtained. The second task will be the subject of a panel discussion.
Optimization model development and comparison

(Georgia Institute of Technology, 1993) Georgakakos, Aristidis P.
Geostatistical Mapping for Hazardous Waste Sites

(Georgia Institute of Technology, 1991) Satkin, Richard L. ; Georgakakos, Aristidis P.

Three commonly used techniques (inverse distance squared, linear interpolation, and kriging) for interpolating spatial data points were compared on the basis of robustness and accuracy. The results demonstrate that 1) kriging is a more robust contouring method; 2) kriging provides explicit measures of estimation accuracy; and 3) kriging balances the risks of misclassification (false positive and false negative error rates).
A Control Model for the Savannah River System

(Georgia Institute of Technology, 1991) Georgakakos, Aristidis P.

Reservoir operation certainly provides ample opportunity to use computer-aided management tools. Except for simple systems, namely, small, single objective reservoirs, where optimal decisions are obvious, the decision making process must take into account a plethora of complicating factors. Uncertain inflows, reservoir and river dynamics, hydroelectric plant characteristics, flood and drought concerns, water supply, energy generation commitments and economics, water quality standards, recreational activities, local and regional water use conflicts and legislation, and public opinion are but a few of the parameters influencing reservoir management decisions. Recent reservoir control research advances combined with fascinating developments in the computer industry provide new opportunities for model use in real time reservoir management. Modern reservoir control methods can now handle dimensionally large systems with both multiple objectives and operational constraints. And, of equal importance, control models can now be implemented on readily accessible microcomputers which encourages potential widespread use and numerous practical applications. Combined with interactive input-output graphics interfaces, management models can be designed to maximize user involvement and provide intuitive understanding of the computations in progress. This paper reports on a state-of-the-art reservoir control model for the regulation of the Savannah River System. Except for model features, emphasis is also placed on how model usage can be maximized within the current organizational decision framework.
Optimal Real-time Activated Sludge Regulation

(Georgia Institute of Technology, 1991) Kabouris, John C. ; Georgakakos, Aristidis P.

An application of optimal control techniques in regulating a conventional activated sludge process (Figure 1) is presented. In this process, organics in the influent wastewater (substrate) serve as energy source for the aerobic growth of microorganisms (biomass or activated sludge) in the biological reactor. The resulting mixed liquor is purified (clarification) by settling of the microbial floes in a following tank (settler). The thickened sludge is recycled to the biological reactor to sustain the biomass amount. To maintain a constant amount of biomass in the system, excess biomass is regularly removed (wastage). The process can be regulated by varying certain inputs such as the wastewater feed point, sludge recycle and wastage rates, aeration rate, and on-line sludge storage and resupply rates. The scope of this paper is to present an application of an optimal control method to a detailed activated sludge model, consisting of a multicomponent biological reactor and a dynamic multilayer settler. A real-world implementation for the Yellow River/ Sweetwater Creek wastewater treatment plant in Gwinnett county is presently being conducted.
Impacts of global warming on reservoir systems management

(Georgia Institute of Technology, 1990) Georgakakos, Aristidis P.