Topics: DTIC Archive, Smith, Andrew N, NAVY ELECTRONICS LAB SAN DIEGO CA, *GRAVITY, *UNDERWATER OBJECTS,...
A circular to rectangular waveguide transition is describe. The transition maintains a constant cutoff wavelength equal to that of the fundamental wave (TE11) in circular waveguide. The parameters of the variable cross-section throughout the transition are computed and normalized to the radius of the circular waveguide.
Topics: DTIC Archive, Pyle, J R, AUSTRALIAN DEFENCE SCIENTIFIC SERVICE MELBOURNE, *WAVEGUIDES, CROSS...
Topics: DTIC Archive, Wenzinger, Carl J., NATIONAL AERONAUTICS AND SPACE ADMINISTRATION WASHINGTON DC,...
In order to study control problems for hybrid systems, we generalize hybrid automata to hybrid games -- say, controller vs. plant. If we specify the continuous dynamics by constant lower and upper bounds, we obtain rectangular games. We show that for rectangular games with objectives expressed in LTL (linear temporal logic), the winning states for each player can be computed, and winning strategies can be synthesized. Our result is sharp, as already reachability is undecidable for...
Topics: DTIC Archive, CALIFORNIA UNIV BERKELEY DEPT OF ELECTRICAL ENGINEERING AND COMPUTER SCIENCES, *GAME...
A study of the use of perforated screens as potential radome structures was conducted. The self-complementary nature of these screens suggests their application for broadbanding or harmonic filters, while aiding the structural integrity of the radome. The adjustment of radome parameters is important to the control of wide angle radiation from radome-covered conformal arrays. The analysis of plane wave scattering by infinitesimally thin periodic screens of rectangular apertures is developed and...
Topics: DTIC Archive, Balzano, Quirino, RAYTHEON CO BEDFORD MA MISSILE SYSTEMS DIV, *RADOMES, APERTURES,...
Let R(1),...,R(m) be rectangles on the plane with sides parallel to the coordinate axes. An algorithm is described to find the contour of F = R(1) U ... U R(m) in o(mlogm + plog(2 sq m/p)) time, where p is the number of edges in the contour. This is o(sq. m) (optimal) in the general case, and o(mlogm) (optimal) when F is without holes (then p or = 8m-4). (Author)
Topics: DTIC Archive, Lipski,Witold , Jr, ILLINOIS UNIV AT URBANA-CHAMPAIGN APPLIED COMPUTATION THEORY...
This paper is concerned with the responses of inelastic rectangular plates to impulsive loadings. The effects of strain hardening and strain rate sensitivity of the material are taken into consideration in this analysis. A variational principle in dynamics of inelastic bodies subject to finite deformation is used to determine the deformation process of the plate. A sandwich plate idealization is employed. The accuracy of the numerical solution is evaluated by comparing it with the existing...
Topics: DTIC Archive, Sureshwara, B, NOTRE DAME UNIV IN COLL OF ENGINEERING, *LOADS(FORCES), *PANELS,...
Mode matching approach is applied to a rectangular waveguide containing a pseudochiral OMEGA slab. From waveguide measurements carried over a few placements of the slab in the guide, the constitutive parameters are extracted. The extraction is performed numerically by a algorithm minimizing the differences between theoretical and measured values of scattering parameters.
Topics: DTIC Archive, Dorko, K., Mazur, J., GDANSK TECHNICAL UNIV (POLAND), *WAVEGUIDES, *ELECTROMAGNETIC...
Topics: DTIC Archive, Lewis, Arthur L, TODD SHIPYARDS CORP SEATTLE WA SEATTLE DIV, *DUCTS, *SHIPBUILDING,...
This report documents a set of functions, written in C++, that can be used to create, position, and rotate rectangles, as well as test for intersection between rectangles. The functions build on functions from the y2DOps namespace (Yager, R. J. Two- Dimensional Translations, Rotations, and Intersections Using C++: U.S. Army Research Laboratory: Aberdeen Proving Ground, MD, to be submitted for publication). The functions have been grouped into the yRectangle2D namespace, which is summarized at...
Topics: DTIC Archive, ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD, *C PROGRAMMING LANGUAGE, *ROTATION,...
Directly comparable drag measurements of an airfoil with a conventional rectangular plan form and an airfoil with a sweptback plan form mounted on a freely falling body have been made.
Topics: DTIC Archive, Mathews, Charles W, NATIONAL AERONAUTICS AND SPACE ADMINISTRATION WASHINGTON DC,...
Contents: Fundamental Equations of Classical Plate Theory; Circular Plates; Elliptical Plates; Rectangular Plates; Parallelogram Plates; Other Quadrilateral Plates; Triangular Plates; Plates of Other Shapes; Anisotropic Plates; Plates With Inplane Forces; Plates With Variable Thickness; and Other Considerations.
Topics: DTIC Archive, Leissa, Arthur W., OHIO STATE UNIV COLUMBUS, *VIBRATION, *PLATES, THICKNESS,...
There is considerable interest in antennas that are high power capable, platform conformal, and steerable. These attributes are often at odds with one another, but we will discuss approaches to mechanically steer the direction of the peak beam of a large-slot array antenna. Traditionally, the slot spacing determines the direction of the radiated main beam of the antenna, and beam steering is accomplished by varying the frequency. But HPM sources are typically incapable of changing the operating...
Topics: DTIC Archive, Courtney, Clifton C, VOSS SCIENTIFIC LLC ALBUQUERQUE NM, *BEAM STEERING, MATHEMATICAL...
Topics: DTIC Archive, Smiley, Robert F, NATIONAL AERONAUTICS AND SPACE ADMINISTRATION WASHINGTON DC,...
In this project we developed imaging systems based on the principles of compressive sensing. We developed advanced signal processing algorithms as well as a hardware testbed. The key idea in CS reconstruction is the realization that most signals encountered in practice are sparse in some domain and the theory of CS exploits such sparsity to dictate that far fewer sampling resources than traditional approaches are needed. Spectral image cubes are particularly well suited for sparse...
Topics: DTIC Archive, DELAWARE UNIV NEWARK, *DEOXYRIBONUCLEIC ACIDS, *ESCHERICHIA COLI, ALCOHOLS,...
The chord length distribution of penetrating radiation in rectangular parallelepipeds is of concern in regard to spacecraft electronic, as single event upsets can be produced by the ionization along the path of a high-energy particle. Both differential and integral chord length distributions are presented here. Two approximations to the integral distribution are discussed. (Author)
Topics: DTIC Archive, Bendel,W L, NAVAL RESEARCH LAB WASHINGTON DC, *SPACECRAFT COMPONENTS, *IONIZING...
Recently several ships with a launching weight of 400 tons have been launched into water by means of a special arrangement whose principal part is constituted by a free floating rectangular pontoon with a carrying capacity of 600 tons.
Topics: DTIC Archive, Leyzerman, V. Y., JOINT PUBLICATIONS RESEARCH SERVICE ARLINGTON VA, *PONTOONS, *SHIP...
Topics: DTIC Archive, Wei-kan, Lin, JOINT PUBLICATIONS RESEARCH SERVICE ARLINGTON VA, *WAVEGUIDES,...
It is shown how to construct a pair of orthogonal v/2 by 2v rectangles for all even v. Also, it is shown how to construct a set of t pairwise orthogonal v/2 by 2v F-rectangles for all even v for which a set of t pairwise orthogonal Latin squares of order v exists. Some situations where these designs are useful in practice are indicated. (Author)
Topics: DTIC Archive, Hedayat,A S, ILLINOIS UNIV AT CHICAGO CIRCLE DEPT OF MATHEMATICS, *RECTANGULAR...
In applications of electrically short antennas such as multiturn loops, variation in ohmic losses due to proximity effects can significantly affect uncorrected estimates of efficiency. The paper investigates experimentally the proximity effects on the current distributions and associated ohmic losses for two identical parallel rectangular cross-section conductors as a function of separation distance and cross-section. The system is operated in a non-transmission-line mode. In the light of...
Topics: DTIC Archive, Burton, Robert W, HARVARD UNIV CAMBRIDGE MA DIV OF ENGINEERING AND APPLIED PHYSICS,...
There are 257 combinatorially distinct eight-vertex polyhedra, of which 14 are deltahedra. Of the 14 deltahedra only the bisdisphenoid, commonly known as the D2d or triangular dodecahedron, both lacks tetrahedral chambers and can be formed by the hybridization of only s,p, and d orbitals. Degenerate single and symmetrical parallel multiple diamond-square-diamond processes involving the 14 eight-vertex deltahedra are tabulated. Among the eleven such processes (six single, two symmetrical double,...
Topics: DTIC Archive, King,R B, GEORGIA UNIV ATHENS DEPT OF CHEMISTRY, *CHEMICALS, *TOPOLOGY,...
The radiation from a rectangular waveguide with a perfectly conducting infinite flange is determined using the modal decomposition matrix (MDM) method. This method uses the tangential boundary condition at the aperture to directly compute the far-field radiation patterns. The fields in the waveguide are expanded in terms of waveguide modes consistent with the approach of Felsen and Marcuvitz. The radiated field is expanded as an inverse Fourier transform and represented at the aperture in terms...
Topics: DTIC Archive, ARMY RESEARCH LAB ADELPHI MD, *DECOMPOSITION, *FAR FIELD, *FLANGES, *RECTANGULAR...
Flow in the entrance region of a parallel plate channel was theoretically investigated by others with little or no experimental verification. Presented is a new method for the analysis which involves a linearization of the inertia terms and the introduction of a stretched axial coordinate. Solutions are obtained for the velocity distribution in an incompressible fluid which is valid from the duct inlet to the fully developed region. An experimental parallel plate channel was operated using...
Topics: DTIC Archive, Snyder, W T, ARNOLD ENGINEERING DEVELOPMENT CENTER ARNOLD AFB TN, *LAMINAR FLOW,...
Topics: DTIC Archive, Tucker, Warren A, NATIONAL AERONAUTICS AND SPACE ADMINISTRATION WASHINGTON DC,...
This report summarizes research during the past year on: the damage mechanism for short (80 ns) pulses of CO2 laser radiation interacting with the cornea epithelium; epithelial damage from multiple-pulse exposures to more penetrating mid-infrared radiation from a Tm:YAG laser at 2.02 micro; and predictions of retinal damage thresholds for exposures to sources with rectangular irradiance distributions. Damage threshold measurements on corneas maintained at 21 C using single 80 ns pulses continue...
Topics: DTIC Archive, McCally, Russell L., JOHNS HOPKINS UNIV LAUREL MD, *RETINA, *INFRARED RADIATION,...
The serious effect of air gaps on the measurement of high dielectric- constant values is discussed. Two measurement techniques are described in which air gaps are made to be insignificant sources of error. The parameters affecting coupling between dielectric resonators are explained. Two pairs of dielectric resonators and three different sizes of waveguides were used to obtain six sets of coupling-coefficient data. The measured values are compared to curves computed from the...
Topics: DTIC Archive, Cohn, S B, RANTEC CORP CALABASAS CA, *RESONATORS, *MICROWAVE FILTERS, MEASUREMENT,...
Heat transfer in turbulent flow was measured in a rectangular channel with a width of 0.254 m and a flow depth of 0.0254 m. Correlations between the Nusselt and Reynolds numbers are given for a range of 3020 Re 22360. A Prandtl number range of 9.90 or = Pr or = 12.28 for water was used in the tests. The results are compared with those of other investigations and show that some well-known correlations underpredict the heat transfer by about 35%.
Topics: DTIC Archive, Haynes,F D, COLD REGIONS RESEARCH AND ENGINEERING LAB HANOVER NH, *HEAT TRANSFER,...
An experimental investigation was conducted to examine the convective heat transfer in straight and curved ducts of rectangular cross-section. The experimental configuration was modeled as infinite parallel plates with one wall at a constant temperature and the opposite wall adiabatic. The experiments were conducted at steady state for turbulent flow. Average Nusselt numbers were used to compare the heat transfer characteristics of the straight and curved sections. The development of...
Topics: DTIC Archive, Daughety,S F, NAVAL POSTGRADUATE SCHOOL MONTEREY CA, *Heat transfer, *Turbulent flow,...
This paper contains and analysis of the complex set of periodic solutions which may occur in a fluid filled vessel of rectangular cross section. A previous analysis by Verma and Keller found only simple eigenvalues for the linearized problem. It is shown herein that at critical values of the vessel aspect ratio double eigenvalues occur. Eight non-linear solution branches are emitted from these double eigenvalues. The solutions along the various branches are derived, and the results displayed...
Topics: DTIC Archive, Bridges,Thomas J, WISCONSIN UNIV-MADISON MATHEMATICS RESEARCH CENTER,...
Topics: DTIC Archive, Eudey, M W, CALIFORNIA UNIV BERKELEY STATISTICAL LAB, *AREA BOMBING, LEADERSHIP,...
The tunnel-induced upwash field for a point element of lift in a rectangular tunnel is shown to consist of three superimposed(i fields that, except for relative position, are independent of the lateral or longitudinal location of the lift element in the tunnel. One of these fields is also independent of the type of tunnel (open or closed) and of the width-height ratio of the tunnel, and the other two, which depend on this ratio, are identical (except, perhaps, for sign).
Topics: DTIC Archive, Katzoff, S, NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH...
An optical fiber cutting machine for use with rectangular or ground cross section fibers has been developed. It combines a sliding-weight tension apparatus with a diamond knife crack initiation mechanism.
Topics: DTIC Archive, Mitchell, Gordon L., WASHINGTON UNIV SEATTLE DEPT OF ELECTRICAL ENGINEERING, *GLASS...
Several low order rational transfer functions have been found which approximate a matched filter for a rectangular pulse. These transfer functions are optimum in the sense that the ratio of peak-signal to rms-noise at the output is maximized to the extent allowed by the available parameters. Normalized transfer functions are given and their frequency and time response are shown graphically. For the most useful cases, realizations normalized in impedance and pulse duration are given which allow...
Topics: DTIC Archive, Craig, John W, MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB, *MATCHED FILTERS,...
The stress intensity factors for single edge cracks in rectangular tensile sheet are studied by using a complex variable form of analysis. The results for deep cracks show a considerable increase in the intensity factors as compared to the case of symmetric edge cracks. Accurate numerical values of the stress intensity factors for the appropriate range of parameters are included.
Topics: DTIC Archive, ARMY MATERIALS RESEARCH AGENCY WATERTOWN MA, *FRACTURE(MECHANICS), COMPLEX VARIABLES,...
The bound-vortex drag was computed for different lift distributions of a single, straight bound-vortex line which, in conformance with Prandtl's airplane wing theory, replaced the hydrofoil. The bound-vortex line was parallel to the undisturbed interface and approximately at the centers of lift of the wing sections of the hydrofoil. The analysis neglected viscous forces and assumed irrotational fluid motion everywhere outside the bound vortex and trailing vortex sheet. Equations give the drag...
Topics: DTIC Archive, Meyer, R. X., HYDROFOIL CORP ANNAPOLIS MD, *HYDROFOILS, *NAVAL ARCHITECTURE,...
Timoshenko's shear coefficient for flexural vibrations of beams was computed for circular, elliptical, parabolic, and oval cross sections. A formula for the shear coefficient was obtained by calculating the frequency (from the free-vibration equations of Timoshenko) at which an infinite beam vibrates without transverse deflections and by equating this with the frequency calculated from the 3-dimensional equations of small vibrations of an elastic body. Approximate frequencies obtained by Hidaka...
Topics: DTIC Archive, MINDLIN, R D, DERESIEWICZ, H, COLUMBIA UNIV NEW YORK, *COEFFICIENTS, CROSS SECTIONS,...
Contents: Introduction; The Admittance Matrices for the Rectangular Waveguides; The Admittance Matrix for the Circular Waveguide; The Excitation Vector; The Electric Field in the Rectangular Waveguides; The Electric Field in the Circular Waveguide; The Tangential Electric Field in the Apertures; Numerical Results; Ordering the Expansion Functions; Roots of Bessel Functions and Their Derivatives.
Topics: DTIC Archive, Mautz, Joseph R, SYRACUSE UNIV NY DEPT OF ELECTRICAL AND COMPUTER ENGINEERING,...
This note derives the distribution of electrical spreading currents along the length of solid conducting objects for which the length substantially exceeds the width. Sources and sinks of DC (or very low frequency AC) current are placed at one end of the object, and the fall-off of spreading current is studied as a function of length. The fall-off can be great; for instance in the case of a solid rectangular object, the fall-off of spreading current along the length is 27dB per unit width....
Topics: DTIC Archive, Eardley, D, MITRE CORP MCLEAN VA JASON PROGRAM OFFICE, *ALTERNATING CURRENT, *DIRECT...
The FORTRAN program SMOOFF (SMOOthing by a Filtered Fourier transform) smooths a noisy function of two variables on a rectangular domain, by minimizing an appropriate functional subject to a least squares constraint. Keywords: Image processing; Data smoothing; Least squares method; Fourier transformation; SMOOFF computer program; Spate 8000 stress analyzer.
Topics: DTIC Archive, Grundy, I H, AERONAUTICAL RESEARCH LABS MELBOURNE (AUSTRALIA), *NOISE, *FOURIER...
Nonnegative matrices are rectangular arrays of nonnegative real numbers. Nonnegative matrices are prevalent in many areas of study. Statistics, Economics, and Chemistry are examples of disciplines that use nonnegative matrices. In this dissertation we examined and produced new results on nonnegative matrices with prescribed spectra. This problem is called the nonnegative inverse eigenvalue problem (NIEP). The NIEP asks which lists of n complex numbers occur as the spectrum of an n x n,...
Topics: DTIC Archive, Egleston, Patricia D, AIR FORCE INST OF TECH WRIGHT-PATTERSONAFB OH, *ARRAYS,...
The stress distribution in rectangular prisms subjected to certain normal end forces on its two opposite faces is a fundamental problem in Applied Mechanics. Reference supplies a method for calculating a symmetric end loading, assuming that the bulk stress on a lateral surface of the rectangular prism is known. Such a measurement could be obtained using advanced thermal emission techniques. The aim of this paper is to extend this concept to the case where an antisymmetric end loading is...
Topics: DTIC Archive, Bennett, J, AERONAUTICAL RESEARCH LABS MELBOURNE (AUSTRALIA), *STRESSES,...
Contents: Equivalent circuit representations and measurement procedures; Variational calculations of the equivalent circuit parameters for thin slots; Comparison of theoretical and experimental results; The study of a half space in terms of spherical transmission lines.
Topics: DTIC Archive, Oliner, Arthur A, POLYTECHNIC INST OF BROOKLYN NY MICROWAVE RESEARCH INST, *WAVEGUIDE...
Newly developed optical diagnostic techniques are used to examine the temporal evolution of wavefront aberrations imposed upon an optical beam as it passes through a rectangular compressible turbulent jet. A recently developed MHz rate system based on a pulse burst laser and ultra highspeed CCD camera is used for flow visualization. A newly developed two-dimensional MHz rate Shack-Hartman wavefront sensor is used to measure the wavefront distortion. The wavefront sensor consists of a HeNe...
Topics: DTIC Archive, OHIO STATE UNIV COLUMBUS DEPT OF MECHANICAL AND AEROSPACE ENGINEERING, *DETECTION,...
An investigation was made: (1) To design and test on integrally stiffened rectangular shear panel, (2) To develop analytical procedures for shear panels subjected to thermomechanical loading, and (3) To compare the analytical and experimental results to evaluate the accuracy of the analysis methods. The body of the report presents a summary description of the methods of analysis which were investigated, the design of the test panel, the experimental program and the analytical and experimental...
Topics: DTIC Archive, WICHITA STATE UNIV KS DEPT OF AERONAUTICAL ENGINEERING, *AIRCRAFT PANELS, *PANELS,...
This report discusses test conducted on wooden pallets made from oak and pine in configurations specified in MIL-P-15011. The hybrid consisted of an oak base and stringers with a pine deck. Three pallet sizes were tested (40- by 48-inches, 42- by 53-inches, and 35- by 45 1/2 inches) to the test requirements of MIL-STD-1660, Design Criteria for Ammunition Unit Loads. As a result of this testing, the pallets satisfied the requirements of MIL-STD-1660 with a rectangular-shaped unit load. Two...
Topics: DTIC Archive, McIntosh, A C, ARMY DEFENSE AMMUNITION CENTER AND SCHOOL SAVANNA IL, *TEST AND...
This paper explains some details related with the choice of the surface or mortar basis functions for the Trefftz finite elements. It is shown that appropriate normalization of the surface basis functions lead to unambiguous definition of the generalized admittance matrix descriptor of the element and to a possibility to define scattering matrix descriptor of the element. A brick element is investigated to illustrate the approach.
Topics: DTIC Archive, Shlepnev, Yuriy, MENTOR GRAPHICS CORP REDMOND WA, *FINITE ELEMENT ANALYSIS,...
The acoustic radiation into a fluid filled infinite half-space from a randomly excited, thin rectangular plate inserted in an infinite baffle is discussed. The analysis is based on the in vacuo modes of the plate. The modal coupling coefficients are evaluated approximately at both low and high (but below acoustic critical) frequencies. An approximate solution of the resulting infinite set of linear simultaneous equations for the plate modal velocity amplitudes is obtained in terms of modal...
Topics: DTIC Archive, Davies, Huw G, MASSACHUSETTS INST OF TECH CAMBRIDGE ACOUSTICS AND VIBRATION LAB,...
An experimental investigation was conducted in a 14- by 22-Foot Subsonic Tunnel to measure the inflow into a scale model helicopter rotor in forward flight mu= 0.40). The measurements were made with a two-component Laser Velocimeter (LV) one chord above the plane formed by the path of the rotor tips (tip-path-plane). A conditional sampling technique was used to determine the position of the rotor at the time that each velocity measurement was made so that the azimuthal fluctuations in velocity...
Topics: DTIC Archive, Hoad, Danny R, *VELOCITY, SCALE MODELS, HELICOPTER ROTORS, BLADES, VARIATIONS,...
We have made advances in the following areas: Data cubes: these recent data-warehouse products need a way to optimize the use of space by selecting some views to maintain permanently. We have identified the 'monotonicy' property choosing one view cannot increase the value of materializing another view as guaranteeing the existence of a polynomial-time competitive (guaranteed to come within a constant fraction of optimum) solution. In one important nonmonotone case, data cubes with indexes on...
Topics: DTIC Archive, Ullman, Jeffrey D., STANFORD UNIV CA DEPT OF COMPUTER SCIENCE, *DATA BASES, *SYSTEMS...
The data contained in this set consists of pressure tire histories measured on the ceiling of an empty rectangular cavity, and were measured as p&t of a joint BAe./DERA programme at the ARA wind tunnel at Bedford during November 1991 The overall programme consisted of several configurations, with bodies positioned at various proximities to the cavity, but the data presented here only considers the empty cavity, configured for both shallow and deep cases. Data were measured using Kulite...
Topics: DTIC Archive, Henshaw, M. J., BRITISH AEROSPACE OPERATIONS LTD BROUGH(UNITED KINGDOM) MILITARY...
