Irrigated Acreage in Georgia's Altamaha River Basin During the Drought Year 2000

Using a "mixed media" approach, which tracts changes in pixel (color) values over the summer indicating changes from dry land to wet land, we have developed estimates for irrigated acreage in the Altamaha River Basin that draws water from ground water or perennial surface water sources. The latter condition is assured given that our estimates come from identified irrigation during the summer of 2000, which was one of Georgia's worst drought years of record. It is improbable that irrigators reliant on non-perennial sources could have successfully irrigated a crop during this drought year. Data provided here should be useful to the state in a number of ways. The state is moving forward with its plans to develop Basin Water Plans, and basic to such plans is information as to the agricultural sectors use of water under worst-case conditions -- conditions of drought. Further, such data can play important roles in efforts by the state to work out solutions to issues related to the use of interstate waters -- ground or surface waters. Working Paper Number 2005-001

Analysis of finite element based numerical methods for acoustic waves, elastic waves, and fluid-solid interactions in the frequency domain

The following thesis studies the acoustic wave equation, the elastic wave equa-tions, a fluid-solid interaction problem, and their finite element approximations in the frequency domain. The focus is on how the solutions depend on the frequency uj, how the error bounds for the finite element approximations depend on the frequency u, and how the mesh size h is constrained by the frequency ω in the finite element approximations. Particular emphasis is on results for high frequency waves. A Rellich identity technique is used to derive an elliptic regularity estimate for the acoustic Helmholtz equation with a first order absorbing boundary condition. The estimate is optimal with respect to the frequency ω. The finite element method for the problem is formulated and analyzed. The finite element analysis leads to two main results. The first is a constraint on the mesh size h in terms of the frequency ω which is necessary to guarantee existence of finite element approximations. The second is an error bound on the finite element approximations which shows explicit ω dependence. Analogous techniques achieve similar results for the elastic Helmholtz equations. An additional difficulty appears in the elastic case because the Lamé operator is only semi-positive definite. The difficulty is overcome first with a regularity argument, and the result is then improved with a Korn-type inequality on the boundary. A fluid-solid interaction problem, which is described by a coupled system of acous-tic and elastic Helmholtz equations, is considered next. Finite element approxima-tions are proposed and analyzed, and optimal order error estimates are established. Parallelizable iterative algorithms are proposed for solving the corresponding finite element equations. The algorithms are based on domain decomposition methods. Strong convergence in the energy norm of the algorithms is proved. Finally, the acoustic Helmholtz equation with a second order absorbing boundary condition is studied. Again, the finite element method is formulated and analyzed, and optimal error estimates are derived with explicit dependence on the frequency, ω. A procedure for recovering the solution in the time domain by numerically approx-imating the inverse Fourier transform is formulated. The procedure is implemented for both the acoustic Helmholtz problem with the first order absorbing boundary condition, and for the acoustic Helmholtz problem with a second order absorbing boundary condition. A computational comparison of the resulting approximate solu-tions is given

From Germany to Australia: Opportunity For a Second Tier Patent System in the United States

Article published in the Michigan State International Law Review

Dam Policy: The Need For Global Governance

Dams have long fascinated engineers, policymakers, and citizens-at-large. No doubt the engineering and architectural details of physical construction of dams are worth study and scrutiny, but it is the human dimension that complicates dam policies. Dams can result in tremendous negative impacts on human populations. Yet, dams provide a source of renewable energy, hydroelectric power. Analyzing these issues in a global perspective offers strategies for policy makers to consider. This paper will analyze the negative impact dams have on humans, illustrate the hydroelectric push for dams and how they impact food production. Finally, global policy strategies will be offered with consideration of environmental accounting and an indication of the future of water and food

An Experimental Study on Air Carryunder Due to Plunging Liquid Jet

The writers would like to congratulate BONETTO & LAHEY (1993) for their excellent paper. The article provides interesting information on the size of the entrained bubbles and on the interactions between air bubbles and turbulence. The writers wish to comment on the definition of 'smooth jet' used by the authors. These comments are based upon the writers' observations on a two-dimensional plunging jet experiment. Further some predictions on the characteristics of air bubbles entrained by 'smooth jets' are presented

Effects of Plunging Breakers on the Gas Contents in the Oceans

The aeration of the ocean contributes to the transfer of oxygen, nitrogen and carbon dioxide between the ocean and the atmosphere. Breaking waves are known to enhance the aeration process by increasing the turbulent mixing and entraining air bubbles. One type of breaking waves, the plunging breaker, can entrain large quantities of air bubbles to depths as large as 10 to 20 metres. The resulting increase of the air-water interface area and the increase of the gas saturation concentration with the depth induce a massive augmentation of air-water gas transfer. The aeration characteristics of plunging breakers in the deep sea are presented using a similarity with plunging jets. A method is developed to predict the sizes of the entrained bubbles, the resulting interface area, the maximum penetration depth and the air-water gas transfer. The results are consistent with experimental observations and emphasise the role of plunging breakers in the aeration process. The authors develop also a prediction model of the gas transfer rate due to plunging breaking waves in deep sea during a storm even

Modelling Air Bubble Entrainment by Plunging Breakers

The aeration characteristics of plunging breakers in the deep sea are described using a similarity with plunging jets. A large two-dimensional jet facility provides new experimental data on the number and sizes of the entrained bubbles and the resulting air-water interface area. The results enable new calculations of the air-water gas transfer contribution of the plunging breakers. The results are consistent with experimental field observations and emphasise the role of plunging breakers in the aeration process of the oceans