An engine trade study for a supersonic STOVL fighter-attack aircraft, volume 1

The best main engine for an advanced STOVL aircraft flight demonstrator was studied. The STOVL aircraft uses ejectors powered by engine bypass flow together with vectored core exhaust to achieve vertical thrust capability. Bypass flow and core flow are exhausted through separate nozzles during wingborne flight. Six near term turbofan engines were examined for suitability for this aircraft concept. Fan pressure ratio, thrust split between bypass and core flow, and total thrust level were used to compare engines. One of the six candidate engines was selected for the flight demonstrator configuration. Propulsion related to this aircraft concept was studied. A preliminary candidate for the aircraft reaction control system for hover attitude control was selected. A mathematical model of transfer of bypass thrust from ejectors to aft directed nozzle during the transition to wingborne flight was developed. An equation to predict ejector secondary air flow rate and ram drag is derived. Additional topics discussed include: nozzle area control, ejector to engine inlet reingestion, bypass/core thrust split variation, and gyroscopic behavior during hover

Interplanetary magnetic fields as a cause of comet tails

Interplanetary magnetic fields as cause of comet tail

Work Sampling as a Method of Evaluating a School Food Service Training Program

Feasible use of work sampling as a method of evaluating school food service employees\u27 performance before and after training sessions on work simplification was studied. Random observations of employees\u27 activities throughout two nine day periods resulted in 1,163 observations the first period and 1,110 the second period. Comparisons of the two periods on the basis of percent of time spent in three work functions and in each of 18 activities showed greatest changes in processing activities, with 2.2 percent more time during the second period; transportation activities, with 2.0 percent less time; cleaning activities, with 1.3 percent more time; and personal delays, with 1.4 percent more time. The general decrease in time spent in transportation and redistribution of the processing activities might be an indication of positive results of the training on work simplification. Comparison of activities by individual workers indicated that those with fewer years experience in school food service who attended training sessions spent less time in transportation activities after training. Employees with many years experience, regardless of their attendance of the training sessions, did not show these changes. Work sampling might be used to indicate the effects of training by comparison of employees\u27 use of time before and after training. Although this work sampling was not specific enough to indicate the actual time of the individual\u27s activity, it could be used to indicate problem areas for further study

A House of Conceits: A Study of the Drama of Jean-Paul Sartre, Albert Camus, Eugene Ionesco, and Samuel Beckett

This study is an effort to define and demonstrate the convention of the conceit as it is employed in the drama of Jean-Paul Sartre, Albert Camus, Eugene Ionesco, and Samuel Beckett. Critics such as Martin Esslin and Jacques Guicharnaud have complained, somewhat bitterly at times, that one or the other of the schools to which these playwrights are assigned belongs to a relatively new convention, which has not been widely understood or even adequately defined. Each of these experts, of course, has attempted to lessen this lack, Esslin with The Theatre of the Absurd, and Guicharnaud, Modern French Theatre: from Giraudoux to Genet. I intend A House of Conceits to be another framework of reference showing the works of Sartre, Camus, Ionesco, and Beckett within their own convention

From Spin Ladders to the 2-d O(3) Model at Non-Zero Density

The numerical simulation of various field theories at non-zero chemical potential suffers from severe complex action problems. In particular, QCD at non-zero quark density can presently not be simulated for that reason. A similar complex action problem arises in the 2-d O(3) model -- a toy model for QCD. Here we construct the 2-d O(3) model at non-zero density via dimensional reduction of an antiferromagnetic quantum spin ladder in a magnetic field. The complex action problem of the 2-d O(3) model manifests itself as a sign problem of the ladder system. This sign problem is solved completely with a meron-cluster algorithm.Comment: Based on a talk by U.-J. Wiese, 6 pages, 12 figures, to be published in computer physics communication

Meron-Cluster Solution of Fermion and Other Sign Problems

Numerical simulations of numerous quantum systems suffer from the notorious sign problem. Important examples include QCD and other field theories at non-zero chemical potential, at non-zero vacuum angle, or with an odd number of flavors, as well as the Hubbard model for high-temperature superconductivity and quantum antiferromagnets in an external magnetic field. In all these cases standard simulation algorithms require an exponentially large statistics in large space-time volumes and are thus impossible to use in practice. Meron-cluster algorithms realize a general strategy to solve severe sign problems but must be constructed for each individual case. They lead to a complete solution of the sign problem in several of the above cases.Comment: 15 pages,LATTICE9

Quantum Monte Carlo Study on Magnetization Processes

A quantum Monte Carlo method combining update of the loop algorithm with the global flip of the world line is proposed as an efficient method to study the magnetization process in an external field, which has been difficult because of inefficiency of the update of the total magnetization. The method is demonstrated in the one dimensional antiferromagnetic Heisenberg model and the trimer model. We attempted various other Monte Carlo algorithms to study systems in the external field and compared their efficiency.Comment: 5 pages, 9 figures; added references for section 1, corrected typo