Decision Analysis on Water Resources Planning and Management for an Arid Metropolitan Center in West Texas

The demand by consumers for public-owned low-priced natural resources is essentially insatiable. When natural resources become scarce the public is agonized by the problem of making an optimum choice or choices from feasible alternatives, preferably from a large number of feasible alternatives. In order to determine the best solutions in terms of satisfying constrained requirements, systematic procedures must be adopted for resources planning and management processes. The Need for a Comprehensive Systems Approach to Urban Water Resources Planning In the past, management and planning programs for water resources have been based primarily on one attribute--money. Sharp criticism has been directed to this type of single-minded planning approach as exemplified in the following speech by Senator Stephen Youngs[38], For a large segment of our water resources program, both the Executive Branch and Congress now scrutinize each project as though it were a narrow commercial undertaking. We concentrate attention on those direct prospective benefits which are strictly measurable in dollars and cents such as the dollar value of property saved from floods, or the amount by which river navigation saves freight charges. We then compare these narrowly construed monetary benefits to cost. In almost every instance, the benefits, human and social values, and vital objectives of national policy which cannot be measured in direct monetary terms often receive only supplementary attention, or none at all. It has become the policy, as stated by Clayton[11], of the National Water Commission, that water resource projects should not be evaluated merely on a pure benefit-cost ratio, but that intangible benefits should also be considered. This prevailing attitude has catalyzed the application of decision analysis embedded with multiattribute characteristics for water resources development decision-making procedures. Decision analysis is a systematic solution procedure which can be used to crystalize a complicated decision problem into manageable subproblems by ranking the decision alternatives in accordance with cardinal values attached to their consequences based on the principles outlines in utility theory. Recent advances in multiattribute utility theory allow the decision maker to assess utilities over intangible benefits such as social acceptance or recreation potential. The relative importance of both intangible and tangible benefits such as cost or quality will all be weighted accordingly in the total utility evaluation. In this manner, the intangible benefits will receive due consideration in the final decision making process

New high-efficiency source of photon pairs for engineering quantum entanglement

We have constructed an efficient source of photon pairs using a waveguide-type nonlinear device and performed a two-photon interference experiment with an unbalanced Michelson interferometer. Parametric down-converted photons from the nonlinear device are detected by two detectors located at the output ports of the interferometer. Because the interferometer is constructed with two optical paths of different length, photons from the shorter path arrive at the detector earlier than those from the longer path. We find that the difference of arrival time and the time window of the coincidence counter are important parameters which determine the boundary between the classical and quantum regime. When the time window of the coincidence counter is smaller than the arrival time difference, fringes of high visibility (80$\pm$ 10%) were observed. This result is only explained by quantum theory and is clear evidence for quantum entanglement of the interferometer's optical paths.Comment: 4 pages, 4 figures, IQEC200

Coherent versus Incoherent Light Scattering from a Quantum Dot

We analyze the light scattered by a single InAs quantum dot interacting with a resonant continuous-wave laser. High resolution spectra reveal clear distinctions between coherent and incoherent scattering, with the laser intensity spanning over four orders of magnitude. We find that the fraction of coherently scattered photons can approach unity under sufficiently weak or detuned excitation, ruling out pure dephasing as a relevant decoherence mechanism. We show how spectral diffusion shapes spectra, correlation functions, and phase-coherence, concealing the ideal radiatively-broadened two-level system described by Mollow.Comment: to appear in PRB 85, 23531

Geometric and Statistical Properties of the Mean-Field HP Model, the LS Model and Real Protein Sequences

Lattice models, for their coarse-grained nature, are best suited for the study of the ``designability problem'', the phenomenon in which most of the about 16,000 proteins of known structure have their native conformations concentrated in a relatively small number of about 500 topological classes of conformations. Here it is shown that on a lattice the most highly designable simulated protein structures are those that have the largest number of surface-core switchbacks. A combination of physical, mathematical and biological reasons that causes the phenomenon is given. By comparing the most foldable model peptides with protein sequences in the Protein Data Bank, it is shown that whereas different models may yield similar designabilities, predicted foldable peptides will simulate natural proteins only when the model incorporates the correct physics and biology, in this case if the main folding force arises from the differing hydrophobicity of the residues, but does not originate, say, from the steric hindrance effect caused by the differing sizes of the residues.Comment: 12 pages, 10 figure

A New Switch and Crossing Design: Introducing the Back to Back Bistable Switch

A new track swtich and crossing (S&C), the back to back bistable (B2B) switch, is proposed that has shown potential to significantly reduce the wheel/rail contact forces through the switch due to its more continuous wheel/rail contact interface and more uniform track stiffness arising from the elimination of the crossing nose. This offers a major reduction on maintenance cost of future S&Cs. The paper explains the concept and identifies the design guidelines for a current layout and uses vehicle/turnout dynamic modelling to predict wheel rail forces through a switch to identify performance improvements relative to a conventional S&C. Both multi-body simulation (MBS) and Finite Element (FE) model have been developed to account for dynamic and thermal analysis. The new design has shown improvements in lateral and vertical wheel-rail contact forces and less relative rail displacements due to thermal effect compared to the conventional S&C

Full Quantum Analysis of Two-Photon Absorption Using Two-Photon Wavefunction: Comparison with One-Photon Absorption

For dissipation-free photon-photon interaction at the single photon level, we analyze one-photon transition and two-photon transition induced by photon pairs in three-level atoms using two-photon wavefunctions. We show that the two-photon absorption can be substantially enhanced by adjusting the time correlation of photon pairs. We study two typical cases: Gaussian wavefunction and rectangular wavefunction. In the latter, we find that under special conditions one-photon transition is completely suppressed while the high probability of two-photon transition is maintained.Comment: 6 pages, 4 figure