New technique for determination of cross-power spectral density with damped oscillators

New cross-power spectral density computation technique has been developed, as well as a technique for discrimination between periodic and random signals. This development is applicable to analysis of any stationary random process, and can be used in the aerospace and transportation fields

Protective telescoping shield for solar concentrator

An apparatus is described for use with a solar concentrator such as a parabolic dish which concentrates sunlight onto a small opening of a solar receiver, for protecting the receiver in the event of a system failure that could cause concentrated sunlight to damage the receiver. The protective apparatus includes a structure which can be moved to a stowed position where it does not block sunlight, to a deployed position. In this position, the structure forms a tube which substantially completely surrounds an axis connecting the receiver opening to the center of the concentrator at locations between the receiver and the concentrator

Lightweight reflector assembly

An inexpensive, lightweight reflective assembly member having good optical quality and particularly adaptable to accommodating temperature variations without providing destructive thermal stresses and reflective slope errors is described. The reflective assembly consists of a thin sheet of glass with appropriate reflective coating and a cellular glass block substrate bonded together. The method of fabrication includes abrading the cellular substrate with an abrasive master die to form an appropriate concave surface. An adhesive is applied to the abraded surface and a lamina reflective surface is placed under a uniform pressure to conform the reflective surface onto the desired abraded surface of the substrate

Tele-autonomous control involving contacts: The applications of a high precision laser line range sensor

The object localization algorithm based on line-segment matching is presented. The method is very simple and computationally fast. In most cases, closed-form formulas are used to derive the solution. The method is also quite flexible, because only few surfaces (one or two) need to be accessed (sensed) to gather necessary range data. For example, if the line-segments are extracted from boundaries of a planar surface, only parameters of one surface and two of its boundaries need to be extracted, as compared with traditional point-surface matching or line-surface matching algorithms which need to access at least three surfaces in order to locate a planar object. Therefore, this method is especially suitable for applications when an object is surrounded by many other work pieces and most of the object is very difficult, is not impossible, to be measured; or when not all parts of the object can be reached. The theoretical ground on how to use line range sensor to located an object was laid. Much work has to be done in order to be really useful

Hydrocarbons identified in extracts from estuarine water accommodated no. 2 fuel oil by gas chromatography-mass spectrometry

Results are presented on a computerized gas chromatograph-mass spectrometer analysis of methylene chloride and n-heptane extracts of a No. 2 fuel oil accommodated estuarine water sample. The analytical method is briefly described, and the limitations on the identifications are categorized. Some attempt was made to determine major and trace constituents in the water accommodate. Altogether 66 hydrocarbon compounds were identified specifically, and 75 compounds were partially identified. Seven compounds could be recognized as major constituents of the water accommodated oil and ten were present only as traces. The aromatic compounds found were alkyl benzenes, naphthalene, tetralin, indane, biphenyl, fluorene, anthracene, and some of their alkyl substituted isomers in the range of carbon numbers C7 to C15. Four n-alkanes, C10 to C13, were found along with four other assorted hydrocarbons

Characterizations of Pseudo-Codewords of LDPC Codes

An important property of high-performance, low complexity codes is the existence of highly efficient algorithms for their decoding. Many of the most efficient, recent graph-based algorithms, e.g. message passing algorithms and decoding based on linear programming, crucially depend on the efficient representation of a code in a graphical model. In order to understand the performance of these algorithms, we argue for the characterization of codes in terms of a so called fundamental cone in Euclidean space which is a function of a given parity check matrix of a code, rather than of the code itself. We give a number of properties of this fundamental cone derived from its connection to unramified covers of the graphical models on which the decoding algorithms operate. For the class of cycle codes, these developments naturally lead to a characterization of the fundamental polytope as the Newton polytope of the Hashimoto edge zeta function of the underlying graph.Comment: Submitted, August 200

Dynamic magnetic response of infinite arrays of ferromagnetic particles

Recently developed techniques to find the eigenmodes of a ferromagnetic particle of arbitrary shape, as well as the absorption in the presence of an inhomogeneous radio-frequency field, are extended to treat infinite lattices of such particles. The method is applied to analyze the results of recent FMR experiments, and yields substantially good agreement between theory and experiment

Narrative coherence in multiple forensic interviews with child witnesses alleging physical and sexual abuse

This study investigated the narrative coherence of children's accounts elicited in multiple forensic interviews. Transcriptions of 56 police interviews with 28 children aged 3–14 years alleging physical and sexual abuse were coded for markers of completeness, consistency and connectedness. We found that multiple interviews increased the completeness of children's testimony, containing on average almost twice as much new information as single interviews, including crucial location, time and abuse‐related details. When both contradictions within the same interview and across interviews were considered, contradictions were not more frequent in multiple interviews. The frequency of linguistic markers of connectedness remained stable across interviews. Multiple interviews increase the narrative coherence of children's testimony through increasing their completeness without necessarily introducing contradictions or decreasing causal‐temporal connections between details. However, as ‘ground truth’ is not known in field studies, further investigation of the relationship between the narrative coherence and accuracy of testimonies is required

Integer Maxima in Power Envelopes of Golay Codewords

This paper examines the distribution of integer peaks amoung Golay cosets in Ζ4. It will prove that the envelope power of at least one element of every Golay coset of Ζ4 of length 2m (for m-even) will have a maximum at exactly 2m+1. Similarly it will be proven that one element of every Golay coset of Ζ4 of length 2m (for m-odd) will have a maximum at exactly 2m+1. Observations and partial arguments will be made about why Golay cosets of Ζ4 of length 2m (for m-even) contain no elements with such a peak

Report from solar physics

A discussion of the nature of solar physics is followed by a brief review of recent advances in the field. These advances include: the first direct experimental confirmation of the central role played by thermonuclear processes in stars; the discovery that the 5-minute oscillations of the Sun are a global seismic phenomenon that can be used as a probe of the structure and dynamical behavior of the solar interior; the discovery that the solar magnetic field is subdivided into individual flux tubes with field strength exceeding 1000 gauss. Also covered was a science strategy for pure solar physics. Brief discussions are given of solar-terrestrial physics, solar/stellar relationships, and suggested space missions