Comparison of several demand systems

Using Monte-Carlo simulation, , we compare the most popular demand systems including the LES, AIDS, BTL, QES, QUAIDS and AIDADS, and find that different models actually have different advantages in estimating different elasticities. Specifically, QES, AIDS and AIDADS models are the best in income, own-price and cross-price elasticities, respectively. Overall, AIDADS model has the best performance. The results indicate that the rank three models are not necessary always better than the rank two models.Comparison, Demand Systems, Monte Carlo, AIDS, Consumer/Household Economics, Demand and Price Analysis, Research Methods/ Statistical Methods,

High temperature constitutive and crack initiation modeling of coated single crystal superalloys

The purpose of this program is to develop life prediction models for anisotropic materials used in gas turbine airfoils. In the base portion of the program, two coated single crystal alloys are being tested. They are PWA 286 overlay coated and PWA 273 aluminide coated PWA 1480 and PWA 286 overlay coated Alloy 185. Viscoplastic constitutive models for these materials are also being developed to predict the cyclic stress-strain histories required for life prediction of the lab specimens and actual airfoil designs

Polarization observables in the longitudinal basis for pseudo-scalar meson photoproduction using a density matrix approach

The complete expression for the intensity in pseudo-scalar meson photoproduction with a polarized beam, target, and recoil baryon is derived using a density matrix approach that offers great economy of notation. A Cartesian basis with spins for all particles quantized along a single direction, the longitudinal beam direction, is used for consistency and clarity in interpretation. A single spin-quantization axis for all particles enables the amplitudes to be written in a manifestly covariant fashion with simple relations to those of the well-known CGLN formalism. Possible sign discrepancies between theoretical amplitude-level expressions and experimentally measurable intensity profiles are dealt with carefully. Our motivation is to provide a coherent framework for coupled-channel partial-wave analysis of several meson photoproduction reactions, incorporating recently published and forthcoming polarization data from Jefferson Lab.Comment: 11 pages, 2 figure

Quantum lattice gases and their invariants

The one particle sector of the simplest one dimensional quantum lattice gas automaton has been observed to simulate both the (relativistic) Dirac and (nonrelativistic) Schroedinger equations, in different continuum limits. By analyzing the discrete analogues of plane waves in this sector we find conserved quantities corresponding to energy and momentum. We show that the Klein paradox obtains so that in some regimes the model must be considered to be relativistic and the negative energy modes interpreted as positive energy modes of antiparticles. With a formally similar approach--the Bethe ansatz--we find the evolution eigenfunctions in the two particle sector of the quantum lattice gas automaton and conclude by discussing consequences of these calculations and their extension to more particles, additional velocities, and higher dimensions.Comment: 19 pages, plain TeX, 11 PostScript figures included with epsf.tex (ignore the under/overfull \vbox error messages

Preliminary Report on High-Performance Computational Structures for Robot Control

In this report we present some initial results of our work completed thus far on Computational Structures for Robot Control . A SIMD architecture with the crossbar interprocessor network which achieves the parallel processing execution time lower bound of o( [a1n ]), where a1 is a constant and n is the number of manipulator joints, for the computation of the inverse dynamics problem, is discussed. A novel SIMD task scheduling algorithm that optimizes the parallel processing performance on the indicated architecture is also delineated. Simulations performed on this architecture show speedup factor of 3.4 over previous related work completed for the evaluation of the specified problem, is achieved. Parallel processing of PUMA forward and inverse kinematics solutions is next investigated using a particular scheduling algorithm. In addition, a custom bit-serial array architecture is designed for the computation of the inverse dynamics problem within the bit-serial execution time lower bound of o(c1k + c2kn), where c1 and c2 are specified constants, k is the word length, and n is the number of manipulator joints. Finally, mapping of the Newton-Euler equations onto a fixed systolic array is investigated. A balanced architecture for the inverse dynamics problem which achieves the systolic execution time lower bound for the specified problem is depicted. Please note again that these results are only preliminary and improvements to our algorithms and architectures are currently still being made