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Showing papers by "Naval Surface Warfare Center published in 1992"


Journal ArticleDOI
TL;DR: The idea is introduced of a "super-wavelet," a linear combination of wavelets that itself is treated as a wavelet that allows the shape of the wavelet to adapt to a particular problem, which goes beyond adapting parameters of a fixed-shape wavelet.
Abstract: Methods are presented for adaptively generating wavelet templates for signal representation and classification using neural networks. Different network structures and energy functions are necessary and are given for representation and classification. The idea is introduced of a "super-wavelet," a linear combination of wavelets that itself is treated as a wavelet. The super-wavelet allows the shape of the wavelet to adapt to a particular problem, which goes beyond adapting parameters of a fixed-shape wavelet. Simulations are given for 1-D signals, with the concepts extendable to imagery. Ideas are discussed for applying the concepts in the paper to phoneme and speaker recognition.

389 citations


Journal ArticleDOI
TL;DR: In this article, a rigorous construction and generalization of the multifractal decomposition for Moran fractals with infinite product measure is presented, which is specified by a system of nonnegative weights in the partition sum.

290 citations


Journal ArticleDOI
TL;DR: In this article, it was shown that the strong upturn reported for the flow stress of copper is not caused by dislocation drag, and the likely explanation is an enhanced rate of dislocation generation.
Abstract: The introduction of viscous drag into a simple thermally activated dislocation model for the low temperature plastic deformation of f.c.c. metals leads to some surprising predictions about their stress-strain behavior. One effect of dislocation drag is to produce a region of tensile instability at small strains for any strain rate. At sufficiently high strain rates there is no region of tensile stability. However, computation of a decreased strain for tensile instability at strain rates greater than 103 s−1, in opposition to experimental measurements, provides evidence that the strong upturn reported for the flow stress of copper is not caused by dislocation drag. The likely explanation is an enhanced rate of dislocation generation.

172 citations


Journal ArticleDOI
TL;DR: The wavelet transform is described, which is particularly useful in those cases in which the shape of the mother wavelet is approximately known a priori and the bank of the VanderLugt matched filters is considered.
Abstract: The wavelet transform is a powerful tool for the analysis of short transient signals. We detail the advantages of the wavelet transform over the Fourier transform and the windowed Fourier transform and consider the wavelet as a bank of the VanderLugt matched filters. This methodology is particularly useful in those cases in which the shape of the mother wavelet is approximately known a priori. A two-dimensional optical correlator with a bank of the wavelet filters is implemented to yield the time-frequency joint representation of the wavelet transform of one-dimensional signals.

145 citations


Journal ArticleDOI
TL;DR: In this paper, the wavelet transform is implemented using an optical multichannel correlator with a bank of wavelet filter filters, which provide a shift-invariant wavelet transformation with continuous translation and discrete dilation.
Abstract: The wavelet transform is implemented using an optical multichannel correlator with a bank of wavelet transform filters. This approach provides a shift-invariant wavelet transform with continuous translation and discrete dilation parameters. The wavelet transform filters can be in many cases simply optical transmittance masks. Experimental results show detection of the frequency transition of the input signal by the optical wavelet transform.

143 citations


Journal ArticleDOI
01 Dec 1992-Energy
TL;DR: In this paper, it was shown that the internal irreversibilities of an endoreversible Carnot engine can be characterized by a single parameter representing the ratio of two entropy differences.

133 citations


Journal ArticleDOI
TL;DR: A method for noise reduction in chaotic systems that is based on projection of the set of points comprising an embedded noisy orbit in R d toward a finite patchwork of best-fit local approximations to an m-dimensional surface.
Abstract: We describe a method for noise reduction in chaotic systems that is based on projection of the set of points comprising an embedded noisy orbit in R d toward a finite patchwork of best-fit local approximations to an m-dimensional surface M'⊂R d , m≤d

132 citations


Journal ArticleDOI
TL;DR: This paper presents the first experimental verification that the sensitivity of a chaotic system to small perturbations (the butterfly effect) can be used to rapidly direct orbits from an arbitrary initial state to an arbitrary accessible desired state.
Abstract: In this paper we present the first experimental verification that the sensitivity of a chaotic system to small perturbations (the ``butterfly effect'') can be used to rapidly direct orbits from an arbitrary initial state to an arbitrary accessible desired state.

131 citations


Proceedings ArticleDOI
TL;DR: In this paper, an interacting multiple model (IMM) algorithm that includes a constant velocity model, a constant speed model with the kinematic constraint for constant speed targets, and the exponentially increasing acceleration (EIA) model for maneuver response is proposed.
Abstract: The interacting multiple model (IMM) algorithm uses multiple models that interact through state mixing to track a target maneuvering through an arbitrary trajectory. However, when a target maneuvers through a coordinated turn, the acceleration vector of the target changes magnitude and direction, and the maneuvering target models commonly used in the IMM (e.g., constant acceleration) can exhibit considerable model error. To address this problem an IMM algorithm that includes a constant velocity model, a constant speed model with the kinematic constraint for constant speed targets, and the exponentially increasing acceleration (EIA) model for maneuver response is proposed. The constant speed model utilizes a turning rate in the state transition matrix to achieve constant speed prediction. The turning rate is calculated from the velocity and acceleration estimates of the constant speed model. The kinematic constraint for constant speed targets is utilized as a pseudomeasurement in the filtering process with the constant speed model. Simulation results that demonstrate the benefits of the EIA model and the kinematic constraint to the IMM algorithm are given. The tracking performance of the proposed IMM algorithm is compared with that of an IMM algorithm utilizing constant velocity and constant turn rate models.

101 citations


Journal ArticleDOI
TL;DR: A joint transform correlation system based on wavelet transforms is introduced that enables this optical correlator to identify the specific features and distinguish similar characters in images.
Abstract: A joint transform correlation system based on wavelet transforms is introduced. The selection of wavelets and the optical wavelet transform of images enables this optical correlator to identify the specific features and distinguish similar characters. Preliminary experimental results are given.

55 citations


Journal ArticleDOI
TL;DR: In this paper, the behavior of prestressed composite girders subjected to negative bending moment was examined experimentally and the experimental results were reported in the literature, but limited experimental results are available.
Abstract: Limited experimental results were reported in the literature on the behavior of prestressed composite girders subjected to negative bending moment. This paper examines experimentally the behavior o...

Journal ArticleDOI
TL;DR: In this article, a method for the structural analysis of prestressed composite steel-concrete girders was studied, where the deflections, forces in the prestressing tendons, and strains in the steel beam and concrete slab were computed throughout the entire loading range up to failure.
Abstract: A method for the structural analysis of prestressed composite steel-concrete girders was studied in this paper. The deflections, forces in the prestressing tendons, and strains in the steel beam and concrete slab of composite girders were computed throughout the entire loading range up to failure. Equations are provided for the calculation of the yield and ultimate load capacities of the girders. The developed analytical models were based on the incremental deformation method. The results of the analytical study were compared with test results of several girders. Reasonably good correlations between analytical and experimental results were obtained. Also, the results showed that a substantial increase in the yield and an increase in the ultimate load capacities can be achieved by adding prestressing tendons to the composite girders and prestressing them. It was determined that the most effective construction sequence for prestressed composite girders in negative moment regions is to posttension the composite girders with tendons in the concrete slabs.

Journal ArticleDOI
TL;DR: Numerical results are presented to show that the fronts are resolved to within a mesh interval and smooth portions of the solution are computed to within the accuracy of the underlying numerical scheme.

Proceedings ArticleDOI
24 Jun 1992
TL;DR: In this article, the optimal solution of a two-stage estimation problem of state estimation in the presence of a dynamical stochastic bias driven by a white or colored process noise is provided.
Abstract: This paper provides the optimal solution of a two-stage estimation problem of state estimation in the presence of a dynamical stochastic bias driven by a white or colored process noise. It is shown that under an algebraic constraint on the statistics of the bias process, the optimal estimate of the system state can be obtained as a linear combination of the outputs of the "bias-free" and bias filters. Because the algebraic constraint can be too restrictive in practice, the results of this paper indirectly prove that all practical two-stage filters are suboptimal.

Journal ArticleDOI
TL;DR: Experiments have been performed where 1018 (UNS G10180), A710(UNS K20747), A537 and HY80 steel specimens, of surface finish corresponding to no. 120, 320, 600, a...
Abstract: Experiments have been performed where 1018 (UNS G10180), A710(UNS K20747), A537 (UNS K02400), and HY80 (UNS K31820) steel specimens, of surface finish corresponding to no. 120, 320, 600, a...

Journal ArticleDOI
TL;DR: A novel scheme for optical realization of wavelet transform for a one-dimensional signal is described and some preliminary experimental results are demonstrated.
Abstract: A novel scheme for optical realization of wavelet transform for a one-dimensional signal is described. Using commercially available components, the proposed system can perform wavelet transform in real time. Some preliminary experimental results are demonstrated.

Journal ArticleDOI
TL;DR: The observation of stochastic resonance in a parametrically driven bistable magnetoelastic buckling-ribbon experiment is reported and a characteristic spectrum for the probability of residence times for this weakly bistables system is observed.
Abstract: We report the observation of stochastic resonance in a parametrically driven bistable magnetoelastic buckling-ribbon experiment. We have found that the parametric addition of white noise increases the signal-to-noise ratio of the response of the ribbon by 10 to 12 dB relative to that of the ribbon with no externally added noise. We have also observed a characteristic spectrum for the probability of residence times for this weakly bistable system

Journal ArticleDOI
TL;DR: A transportable Fortran subroutine based on this algorithm is currently in use and is accurate to 14 significant digits when precision is not restricted by inherent error.
Abstract: An algorithm is given for evaluating the incomplete beta function ratio Ix(a,b) and its complement 1 - Ix(a,b). A new continued fraction and a new asymptotic series are used with classical results. A transportable Fortran subroutine based on this algorithm is currently in use. It is accurate to 14 significant digits when precision is not restricted by inherent error.

Journal ArticleDOI
TL;DR: In this article, the authors investigated source/fiber/detector interactions, and developed a simple model for multimode fiber system information capacity, where simplified expressions for the baseband impulse and frequency responses of each component were given along with relationships between the theoretical impulse response root mean square (RMS) width and the component rise time or bandwidth.
Abstract: The use of multimode fiber in digital fiber-optic data links requires simple and accurate procedures for the calculation of data line component bandwidth and rise time responses. The author investigates source/fiber/detector interactions, to develop a simple model for multimode fiber system information capacity. Simplified expressions for the baseband impulse and frequency responses of each component are given along with relationships between the theoretical impulse response root mean square (RMS) width and the component rise time or bandwidth. The application of the central limit theorem to the system yields expressions for the composite system rise time and bandwidth which contain correction factors to those that would be obtained using the normal Gaussian assumptions. >

Journal ArticleDOI
TL;DR: It is shown that a causal (i.e., zero valued before signal arrives) and analytical mother wavelet still guarantees completeness, which permits the selection of mother wavelets that better match causal analytical input signals.
Abstract: The causal analytical wavelet transform employs exponentially decaying nonsinusoidal wideband transient bases of compact support. The basis set h ab ( t ) = h [( t - b )/ a ]√ a is called daughter wavelets, which are constructed from a causal analytical mother wavelet h ( t ) by means of the dilation parameter a and the translation parameter b . We show that a causal (i.e., zero valued before signal arrives) and analytical mother wavelet still guarantees completeness. This permits the selection of mother wavelets that better match causal analytical input signals. An optical architecture is described for real-time implementation.

Journal ArticleDOI
TL;DR: In this article, an extended X-ray-absorption near-edge structure (XANES) and extended-x-ray absorption fine-structure (EXAFS) measurements have been performed on the calcium K edge and manganese K edge of a sample doped with manganous at molecular concentrations of 0.1--2.5 %.
Abstract: X-ray-absorption near-edge structure (XANES) and extended-x-ray-absorption fine-structure (EXAFS) measurements have been performed on the calcium K edge and manganese K edge of ${\mathrm{CaF}}_{2}$ doped with manganese at molecular concentrations of 0.1--2.5 %. The results are compared to other measurements of the calcium K edge in ${\mathrm{CaF}}_{2}$ and the Mn K edge in various manganese compounds. Major features in the XANES spectra are tentatively identified with transitions to high-symmetry points of the ${\mathrm{CaF}}_{2}$ energy bands in a one-electron picture. Expected deviations from the structure predicted by the one-electron formalism are discussed. The EXAFS analysis shows a reduction in the manganese-fluorine distance of (3.9\ifmmode\pm\else\textpm\fi{}0.4)% as compared to the calcium-fluorine separation in the doped or undoped samples. This compares well with previous results obtained by EPR. A significant increase in disorder of the first shell around the Mn dopant ion is observed as compared to the Ca ion. The significance of this shell contraction and disorder is discussed in terms of possible defect structures in the material.

Journal ArticleDOI
TL;DR: It is shown that the optical implementations of both discrete and continuous wavelet transforms can be considered theoretically and shown that they can be stored and utilized in parallel large banks of wavelets to allow "instantaneous" DWT of functions of a single variable and (relatively) fast DWTs of two-dimensional functions.
Abstract: We consider theoretically the optical implementations of both discrete and continuous wavelet transforms. Discrete wavelet transforms (DWTs) require sums (or integrals) of the product of the input function with multiple stored functions (wavelets with various shifts and scales). The inverse DWT requires the same, exceptthe given function is replaced by the wavelet coefficients determined by the DWT. We show that we can store and utilize in parallel large banks of wavelets. This should allow "instantaneous" DWT of functions of a single variable and (relatively) fast DWTs of two-dimensional functions. Of course, the same applies to the inverse DWTs. A true continuous wavelet transform (CWT) must be continuous in both shift and scale. By means of a continuous anamorphic transformation of a one-dimensional signal and a suitable choice of kernel or filter, we can allow a normal two-dimensional optical Fourier transform image processor to perform a CWT.

Journal ArticleDOI
TL;DR: An optical implementation of the wavelet and inverse wavelet transforms and a multichannel optical processing system with two gratings is set up to obtain image representation and image reconstruction.

Proceedings ArticleDOI
16 Dec 1992
TL;DR: Simulation results for comparing the performances of the IMM and IMAM algorithms are given, together with a computational count for the two algorithms indicate that the IMAM algorithm requires approximately 43% of the computations of theIMM algorithm when a constant velocity and two constant accelerations models are used.
Abstract: The interacting multiple bias model (IMBM) algorithm is presented as an approach to state estimation for systems with Markovian switching coefficients that can be isolated to a system bias. The IMBM algorithm utilizes the interacting multiple model (IMM) algorithm and recent developments in two-stage state estimation. The IMBM algorithm is well suited for tracking maneuvering targets, where the target acceleration is modeled as a system bias. This algorithm is called the interacting multiple acceleration model (IMAM) algorithm. Simulation results for comparing the performances of the IMM and IMAM algorithms are given, together with a computational count for the two algorithms which indicate that the IMAM algorithm requires approximately 43% of the computations of the IMM algorithm when a constant velocity and two constant accelerations models are used. >

Journal ArticleDOI
TL;DR: In this article, a mechanism for the coupling of two ferromagnetic films separated by a metallic paramagnetic film is derived, where the coupling oscillates in sign as a function of the thickness of the paramagnetic layer, with the long range period of the oscillation determined by the Fermi wavevector for the paramagnet.

PatentDOI
14 Sep 1992
TL;DR: In this paper, a capacitive probe having a grounded rd electrode positioned therebetween shield a probe circuit, provides mutual capacitance measurements which way as a function of changes in impedance of dielectric material being monitored as it undergoes a curing process.
Abstract: Conductive measuring electrodes, of a capacitive probe having a grounded rd electrode positioned therebetween shield a probe circuit, provides mutual capacitance measurements which way as a function of changes in impedance of dielectric material being monitored as it undergoes a curing process. The probe is positioned in non-embedded relation to the dielectric material to form a sensitivity region therein through which an electric field extends between the conductive measuring electrodes of the probe to establish said variable mutual capacitance measurements without extraneous influences.

Journal ArticleDOI
01 May 1992
TL;DR: The presence of man-made objects in gray-scale images has been successfully detected using a new class of density estimation neural networks to analyze power law signatures.
Abstract: The detection of man-made objects in natural terrain is important in both the targeting and terminal homing phase of modern warfare. The presence of man-made objects in gray-scale images has been successfully detected using a new class of density estimation neural networks to analyze power law signatures. The complex nature of the discriminant surface relating these features has been elucidated using these adaptive mixture networks.

Journal ArticleDOI
TL;DR: In this article, the influence of transverse rolling passes on the recrystallization texture was investigated in an effort to strengthen the {111} 〈uvw〉 type components and reduce the intensity of the {100} ǫ 0vw  components, improve the uniformity of the microstructure, and refine the grain size in high-purity tantalum plate.
Abstract: The influence of transverse rolling passes on the recrystallization texture was investigated in an effort to strengthen the {111} 〈uvw〉 type components and reduce the intensity of the {100} 〈0vw〉 components, improve the uniformity of the microstructure, and refine the grain size in high-purity tantalum plate. Tantalum, from three different ingot breakdown processes, received an additional 80 pct reduction in the transverse direction (perpendicular to the ingot centerline) in the processing schedule prior to final annealing. This work investigated the influence of the additional transverse rolling passes on the development of texture in the as-rolled tantalum and also in rolled plus annealed tantalum. After annealing, the tantalum plates had significantly strengthened {111} 〈uvw〉 crystallographic orientations, not only for the side forged process, but also for the upset and side forged tantalum. For tantalum processed by extrusion, the transverse rolling did not improve the final recrystallized texture.

Journal ArticleDOI
TL;DR: In this article, the authors describe results of application to coarsely sampled Lorenz time series of an algorithm for noise reduction, which does not depend on having detailed prior information about system dynamics.

Journal ArticleDOI
13 Apr 1992
TL;DR: In this article, the magnetic and magnetostrictive properties of Tb/sub x/Dy/sub 1-x alloys were measured in the region of large magnetostriction to anisotropy ratios (x=0.5, 0.6, and 0.67).
Abstract: The magnetic and magnetostrictive properties of the Tb/sub x/Dy/sub 1-x/ highly magnetostrictive alloys were measured in the region of large magnetostriction to anisotropy ratios (x=0.5, 0.6, and 0.67). Magnetizations and magnetostrictions under compressive stresses up to 25 MPa and fields up to 2 kOe were compared to theoretical curves. Field dependences clearly display magnetization discontinuities and magnetic rotation regions. From these data and from corresponding elastic modulus measurements, permeabilities, piezomagnetic d-constants (d/sub 33/), and elastic compliances were calculated. For some values of stress and magnetic field, Delta E effects >10 and coupling factors (k/sub 33/) approach unity. >