Multisymplectic formulation of vielbein gravity. De Donder-Weyl formulation, Hamiltonian (n-1)-forms

We consider the De Donder-Weyl (DW) Hamiltonian formulation of the Palatini action of vielbein gravity formulated in terms of the solder form and spin connection, which are treated as independent variables. The basic geometrical constructions necessary for the DW Hamiltonian theory of vielbein gravity are presented. We reproduce the DW Hamilton equations in the multisymplectic and pre-multisymplectic formulations. We also give basic examples of Hamiltonian (n-1)-forms and related Poisson brackets.Comment: 47 pages, 0 figure v4 Minor corrections. (notations more light

Optimal control theory : a method for the design of wind instruments

It has been asserted previously by the author that optimal control theory can be a valuable framework for theoretical studies about the shape that a wind instrument should have in order to satisfy some optimization criterion, inside a fairly general class. The purpose of the present work is to develop this new approach with a look at a specific criterion to be optimized. In this setting, the Webster horn equation is regarded as a controlled dynamical equation in the space variable. Pressure is the state, the control being made of two parts: one variable part, the inside diameter of the duct and one constant part, the weights of the elementary time-harmonic components of the velocity potential. Then one looks for a control that optimizes a criterion related to the definition of an {oscillation regime} as the cooperation of several natural modes of vibration with the excitation, the {playing frequency} being the one that maximizes the total generation of energy, as exposed by A.H. Benade, following H. Bouasse. At the same time the relevance of this criterion is questioned with the simulation results.Comment: To appear in Acta Acustica united with Acustica, 201

Restoring Prosperity: The State Role in Revitalizing America's Older Industrial Cities

Presents a five-part agenda and organizing plan to reinvigorate the nation's older industrial cities, and aims to mobilize governors, legislative leaders, and local constituencies toward advancing urban reform

Off-lattice Kinetic Monte Carlo simulations of strained heteroepitaxial growth

An off-lattice, continuous space Kinetic Monte Carlo (KMC) algorithm is discussed and applied in the investigation of strained heteroepitaxial crystal growth. As a starting point, we study a simplifying (1+1)-dimensional situation with inter-atomic interactions given by simple pair-potentials. The model exhibits the appearance of strain-induced misfit dislocations at a characteristic film thickness. In our simulations we observe a power law dependence of this critical thickness on the lattice misfit, which is in agreement with experimental results for semiconductor compounds. We furthermore investigate the emergence of strain induced multilayer islands or "Dots" upon an adsorbate wetting layer in the so-called Stranski-Krastanov (SK) growth mode. At a characteristic kinetic film thickness, a transition from monolayer to multilayer islands occurs. We discuss the microscopic causes of the SK-transition and its dependence on the model parameters, i.e. lattice misfit, growth rate, and substrate temperature.Comment: 17 pages, 6 figures Invited talk presented at the MFO Workshop "Multiscale modeling in epitaxial growth" (Oberwolfach, Jan. 2004). Proceedings to be published in "International Series in Numerical Mathematics" (Birkhaeuser

Studies of lunar soil mechanics, final report, jun. 15, 1963 - dec. 15, 1964

Properties of simulated lunar soils in lunar environmen

Studies of lunar and Martian soil mechanics Third quarterly progress report, Jun. - Sep. 15, 1965

Lunar and Martian soil mechanics - soil shear strength and penetration resistance under high vacuum, and composition of desorbed gases from heated soil sample

The effects of unionization in an R&D growth model with (In)determinate equilibrium

This paper extends an R&D-based growth model of the Rivera-Batiz and Romer-type [Quarterly Journal of Economics 106 (1991) 531] endogenous growth model by embodying a union with elastic labor to investigate the effects of unionization on employment and growth by highlighting the essence of internal conflict within the union. It is shown that an increase in the union’s bargaining power or a union which is more employment-oriented boosts employment and economic growth when the balanced growth equilibrium is determinate. On the other hand, if the union is more wage-oriented, employment and economic growth are enhanced when the balanced growth equilibrium is indeterminate.Union, Collective bargaining, R&D, Indeterminacy, Economic growth

Crisis protests in Germany, Occupy Wall Street, and Mietshäuser Syndikat: Antinomies of current Marxist- and anarchist-inspired movements and their convergence

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.The theoretical and practical narrowings and possibilities of the cross-fertilisation of current Marxist- and anarchist-inspired movements are the subject of this paper. The main arguments are illustrated by an analysis of the crisis protests in Germany in 2009-2010 and the Occupy Wall Street movement in the USA. The German apartment-house syndicate (‘Mietshäuser Syndikat’) functions as an example showing how the different strategies of the two political strands can be combined in practice

A force balance system for the measurement of skin friction drag force in the presence of large vibrations and temperatures

Design of counterbalance system for skin friction drag measurements on hypersonic vehicle