Design and manufacture of direct current torquer amplifiers Final summary report

Design and manufacture of direct current torquer amplifier with pulse width modulation circui

Simple models for the shuttle remote manipulator system

The investigation is aimed at establishing a series of simple models which can be used to study the forces and moments which occur due to the reaction control system (RCS) jet plume firings during a deployment or retrieval of an IUS type payload. The models considered in this investigation are primarily planar in nature. In this study primary attention is given to the roles the payload play in determining the overall moments on the remote manipulator system arm

Beyond Dependency: Strategies for Saving Foundations

We have generally tried to depend on the force of argument to win the day against the structural forces that have driven this decline. Yet foundations generally operates from a position of relative weakness in schools of education: we provide service to programs but generally do not have our own strong programs. We “take” enrollment from other departments, but do not “give” enrollment to them or bring independent enrollment to the school. This leaves foundations in a position of dependency. The core argument of this paper is that we need to move beyond dependency toward a vision of foundations as, at least in part, a provider of robust (if collaborative) programs of its own, and we discuss a range of strategies designed to foster the development of such programs. Amidst the current environment, we believe that foundations will find it increasingly difficult to make our arguments stick without the associated power to make ourselves heard

The response of interferometric gravitational wave detectors

The derivation of the response function of an interferometric gravitational wave detector is a paradigmatic calculation in the field of gravitational wave detection. Surprisingly, the standard derivation of the response wave detectors makes several unjustifiable assumptions, both conceptual and quantitative, regarding the coordinate trajectory and coordinate velocity of the null geodesic the light travels along. These errors, which appear to have remained unrecognized for at least 35 years, render the "standard" derivation inadequate and misleading as an archetype calculation. Here we identify the flaws in the existing derivation and provide, in full detail, a correct derivation of the response of a single-bounce Michelson interferometer to gravitational waves, following a procedure that will always yield correct results; compare it to the "standard", but incorrect, derivation; show where the earlier mistakes were made; and identify the general conditions under which the "standard" derivation will yield correct results. By a fortuitous set of circumstances, not generally so, the final result is the same in the case of Minkowski background spacetime, synchronous coordinates, transverse-traceless gauge metric perturbations, and arm mirrors at coordinate rest.Comment: 10 pages, one figure, as accepted to PR

A stochastic template placement algorithm for gravitational wave data analysis

This paper presents an algorithm for constructing matched-filter template banks in an arbitrary parameter space. The method places templates at random, then removes those which are "too close" together. The properties and optimality of stochastic template banks generated in this manner are investigated for some simple models. The effectiveness of these template banks for gravitational wave searches for binary inspiral waveforms is also examined. The properties of a stochastic template bank are then compared to the deterministically placed template banks that are currently used in gravitational wave data analysis.Comment: 14 pages, 11 figure

A new numerical method to construct binary neutron star initial data

We present a new numerical method for the generation of binary neutron star initial data using a method along the lines of the the Wilson-Mathews or the closely related conformal thin sandwich approach. Our method uses six different computational domains, which include spatial infinity. Each domain has its own coordinates which are chosen such that the star surfaces always coincide with domain boundaries. These properties facilitate the imposition of boundary conditions. Since all our fields are smooth inside each domain, we are able to use an efficient pseudospectral method to solve the elliptic equations associated with the conformal thin sandwich approach. Currently we have implemented corotating configurations with arbitrary mass ratios, but an extension to arbitrary spins is possible. The main purpose of this paper is to introduce our new method and to test our code for several different configurations.Comment: 18 pages, 8 figures, 1 tabl

The equivalence principle, uniformly accelerated reference frames, and the uniform gravitational field

The relationship between uniformly accelerated reference frames in flat spacetime and the uniform gravitational field is examined in a relativistic context. It is shown that, contrary to previous statements in the pages of this journal, equivalence does not break down in this context. No restrictions to Newtonian approximations or small enclosures are necessary

Removing non-stationary, non-harmonic external interference from gravitational wave interferometer data

We describe a procedure to identify and remove a class of non-stationary and non-harmonic interference lines from gravitational wave interferometer data. These lines appear to be associated with the external electricity main supply, but their amplitudes are non-stationary and they do not appear at harmonics of the fundamental supply frequency. We find an empirical model able to represent coherently all the non-harmonic lines we have found in the power spectrum, in terms of an assumed reference signal of the primary supply input signal. If this signal is not available then it can be reconstructed from the same data by making use of the coherent line removal algorithm that we have described elsewhere. All these lines are broadened by frequency changes of the supply signal, and they corrupt significant frequency ranges of the power spectrum. The physical process that generates this interference is so far unknown, but it is highly non-linear and non-stationary. Using our model, we cancel the interference in the time domain by an adaptive procedure that should work regardless of the source of the primary interference. We have applied the method to laser interferometer data from the Glasgow prototype detector, where all the features we describe in this paper were observed. The algorithm has been tuned in such a way that the entire series of wide lines corresponding to the electrical interference are removed, leaving the spectrum clean enough to detect signals previously masked by them. Single-line signals buried in the interference can be recovered with at least 75 % of their original signal amplitude.Comment: 14 pages, 5 figures, Revtex, psfi

Economics of Federal Irrigation Projects in the Missouri Basin

A greatly expanded Federal program for irrigation development is planned for the Missouri Basin. Under the Flood Control Act of 1944, nearly 5 million acres were proposed for irrigation; and in addition, about half a million acres under irrigation were to receive supplemental water. Nearly one-half of the new irrigation planned was to be located in North and South Dakota. The Missouri-Souris Unit in North Dakota of more than a million acres and the Oahe Unit in South Dakota of three-quarter million acres are the two largest under consideration. Both units are receiving further study to determine the suitability of the soils for irrigation. The irrigation facilities in the Missouri The irrigation facilities in the Missouri Basin would be built and financed largely by the Federal Government. Consequently, certain questions concerning evaluation, accounting of costs, allocations of costs to various purposes, repayments by beneficiaries and similar questions are of public interest. No less important are factors such as the suitability of soils for irrigation, adequacy of water supplies, repayment capacity and related farm problems. However, much less information has been available to the public on some of the over-all economic aspects of the proposed development, and these are the concern of this report. While it is recognized that there are important benefits from irrigation, these are not taken up here because they have been discussed in other reports. (See more in text