Development of a Straw Tube Chamber with Pickup-Pad Readout

We have developed a straw tube chamber with pickup-pad readout. The mechanism for signal pickup, the size of the pickup signal, and the distribution of signals among neighboring pads are discussed. We have tested a prototype chamber in a beamtest at Brookhaven National laboratory and have measured chamber efficiencies in excess of 99%.Comment: 7 pages, 8 figures, 2 tables. Talk presented at DPF '99 Meeting, UCL

Coupled thermo-mechanical damage modelling for structural steel in fire conditions

This paper aims at developing a coupled thermo-mechanical damage model for structural 6 steel at elevated temperatures. The need for adequate modelling of steel deterioration behaviour 7 remains a challenging task in structural fire engineering because of the complexity inherent in 8 the damage states of steel under combined actions of mechanical and fire loading. A fully three9 dimensional damage-coupled constitutive model is developed in this work based on the hypothesis 10 of effective stress space and isotropic damage theory. The new coupling model, adapted from 11 an enhanced Lemaitre’s ductile damage equation and taking into account temperature-dependent 12 thermal degradation, is a phenomenological approach where the underlying mechanisms that govern 13 the damage processes have been retained. The proposed damage model comprises a limited number 14 of parameters that could be identified using unloading slopes of stress-strain relationships through 15 tensile coupon tests. The proposed damage model is successfully implemented in the finite element 16 software ABAQUS and validated against a comprehensive range of experimental results. The 17 damage-affected structural response is accurately reproduced under various loading conditions and 18 a wide temperature range, demonstrating that the proposed damage model is a useful tool in giving a 19 realistic representation of steel deterioration behaviour for structural fire engineering applications

Manual of phosphoric acid fuel cell power plant optimization model and computer program

An optimized cost and performance model for a phosphoric acid fuel cell power plant system was derived and developed into a modular FORTRAN computer code. Cost, energy, mass, and electrochemical analyses were combined to develop a mathematical model for optimizing the steam to methane ratio in the reformer, hydrogen utilization in the PAFC plates per stack. The nonlinear programming code, COMPUTE, was used to solve this model, in which the method of mixed penalty function combined with Hooke and Jeeves pattern search was chosen to evaluate this specific optimization problem

Phosphoric acid fuel cell power plant system performance model and computer program

A FORTRAN computer program was developed for analyzing the performance of phosphoric acid fuel cell power plant systems. Energy mass and electrochemical analysis in the reformer, the shaft converters, the heat exchangers, and the fuel cell stack were combined to develop a mathematical model for the power plant for both atmospheric and pressurized conditions, and for several commercial fuels

Manual of phosphoric acid fuel cell power plant cost model and computer program

Cost analysis of phosphoric acid fuel cell power plant includes two parts: a method for estimation of system capital costs, and an economic analysis which determines the levelized annual cost of operating the system used in the capital cost estimation. A FORTRAN computer has been developed for this cost analysis

Manual of phosphoric acid fuel cell stack three-dimensional model and computer program

A detailed distributed mathematical model of phosphoric acid fuel cell stack have been developed, with the FORTRAN computer program, for analyzing the temperature distribution in the stack and the associated current density distribution on the cell plates. Energy, mass, and electrochemical analyses in the stack were combined to develop the model. Several reasonable assumptions were made to solve this mathematical model by means of the finite differences numerical method

Black Holes in Higher-Derivative Gravity

Extensions of Einstein gravity with higher-order derivative terms arise in string theory and other effective theories, as well as being of interest in their own right. In this paper we study static black-hole solutions in the example of Einstein gravity with additional quadratic curvature terms. A Lichnerowicz-type theorem simplifies the analysis by establishing that they must have vanishing Ricci scalar curvature. By numerical methods we then demonstrate the existence of further black-hole solutions over and above the Schwarzschild solution. We discuss some of their thermodynamic properties, and show that they obey the first law of thermodynamics.Comment: Typos corrected, discussion added, figure changed. 4 pages, 6 figure

Toolbox for entanglement detection and fidelity estimation

The determination of the state fidelity and the detection of entanglement are fundamental problems in quantum information experiments. We investigate how these goals can be achieved with a minimal effort. We show that the fidelity of GHZ and W states can be determined with an effort increasing only linearly with the number of qubits. We also present simple and robust methods for other states, such as cluster states and states in decoherence-free subspaces.Comment: 5 pages, no figures, v3: final version, to appear as a Rapid Communication in PR

Gaussian Effective Potential and the Coleman's normal-ordering Prescription : the Functional Integral Formalism

For a class of system, the potential of whose Bosonic Hamiltonian has a Fourier representation in the sense of tempered distributions, we calculate the Gaussian effective potential within the framework of functional integral formalism. We show that the Coleman's normal-ordering prescription can be formally generalized to the functional integral formalism.Comment: 6 pages, revtex; With derivation details and an example added. To appear in J. Phys.