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Showing papers by "Naval Surface Warfare Center published in 1996"


Journal ArticleDOI
TL;DR: This is the first demonstration of stochastic resonance in neuronal networks from the brain by using a time varying electric field to deliver both signal and noise directly to a network of neurons from mammalian brain.
Abstract: Stochastic resonance, a nonlinear phenomenon in which random noise optimizes a system’s response to a signal, has been postulated to provide a role for noise in information processing in the brain. In these experiments, a time varying electric field was used to deliver both signal and noise directly to a network of neurons from mammalian brain. As the magnitude of the stochastic component of the field was increased, resonance was observed in the response of the neuronal network to a weak periodic signal. This is the first demonstration of stochastic resonance in neuronal networks from the brain. [S0031-9007(96)01583-9]

330 citations


Journal ArticleDOI
TL;DR: Modulation of neuronal activity in these experiments was readily observed at field strengths < or = 5-10 mV/mm and in vivo application of these results may be feasible.
Abstract: 1. The effects of relatively small external DC electric fields on synchronous activity in CA1 and CA3 from transverse and longitudinal type hippocampal slices were studied. 2. To record neuronal activity during significant field changes, differential DC amplification was employed with a reference electrode aligned along an isopotential with the recording electrode. 3. Suppression of epileptiform activity was observed in 31 of 33 slices independent of region studied and type of slice but was highly dependent on field orientation with respect to the apical dendritic-somatic axis. 4. Modulation of neuronal activity in these experiments was readily observed at field strengths < or = 5–10 mV/mm. Suppression was seen with the field oriented (positive to negative potential) from the soma to the apical dentrites. 5. In vivo application of these results may be feasible.

200 citations


Journal ArticleDOI
TL;DR: In this article, a new average-value model of a synchronous machine fed load-commutated converter is presented in which the stator dynamics are combined with the DC link dynamics.
Abstract: A new average-value model of a synchronous machine fed load-commutated converter is set forth in which the stator dynamics are combined with the DC link dynamics. This model is shown to he extremely accurate in predicting system transients and in predicting frequency-domain characteristics such as the impedance looking into the synchronous machine fed load-commutated converter. The model is verified against a detailed computer simulation and against a hardware test system, thus providing a three-way comparison. The proposed model is shown to be much more accurate than models in which the stator dynamics are neglected.

130 citations


Book
01 Jan 1996
TL;DR: This second edition provides illustrative example sets to simplify the process of learning and mastering the powerful, flexible, and easy-to-use graphics environment in MATLAB.
Abstract: From the Publisher: Graphics and GUIs with MATLAB completely examines the MATLAB graphics system, describing the enhancements and added features of MATLAB 5. This second edition provides illustrative example sets to simplify the process of learning and mastering the powerful, flexible, and easy-to-use graphics environment. This book serves technical professionals using MATLAB's plotting capabilities, MATLAB programmers learning about the graphics environment, anyone creating pictures using mathematical expressions.

113 citations


Journal ArticleDOI
TL;DR: This work develops an ANN method to construct an optimum mother wavelet that can organize sensor input data in the multiresolution format that seems to become essential for brainstyle computing.

97 citations


Journal ArticleDOI
TL;DR: In this paper, an approach to the investigation of molecular structures in disordered solids, using two-dimensional (2D) nuclear magnetic resonance (NMR) exchange spectroscopy with magic angle spinning (MAS), is described.
Abstract: An approach to the investigation of molecular structures in disordered solids, using two‐dimensional (2D) nuclear magnetic resonance (NMR) exchange spectroscopy with magic angle spinning (MAS), is described. This approach permits the determination of the relative orientation of two isotopically labeled chemical groups within a molecule in an unoriented sample, thus placing strong constraints on the molecular conformation. Structural information is contained in the amplitudes of crosspeaks in rotor‐synchronized 2D MAS exchange spectra that connect spinning sideband lines of the two labeled sites. The theory for calculating the amplitudes of spinning sideband crosspeaks in 2D MAS exchange spectra, in the limit of complete magnetization exchange between the labeled sites, is presented in detail. A new technique that enhances the sensitivity of 2D MAS exchange spectra to molecular structure, called orientationally weighted 2D MAS exchange spectroscopy, is introduced. Symmetry principles that underlie the cons...

94 citations


Journal ArticleDOI
TL;DR: In this article, the problem of tracking maneuvering targets with multiple sensors is illustrated through an example involving target motion in a single coordinate in which it is shown that with two sensors one can have worse track performance than a single sensor.
Abstract: In many multisensor systems the number and type of sensors supporting a particular target track can vary with time due to the mobility, type, and resource limitations of the individual sensors. This variability in the configuration of the sensor system poses a significant problem when tracking maneuvering targets because of the uncertainty in the target motion model. A Kalman filter is often employed to filter the position measurements for estimating the position, velocity, and acceleration of a target. When designing the Kalman filter, the process noise (acceleration) variance Q/sub k/ is selected such that the 65 to 95% probability region contains the maximum acceleration level of the target. However, when targets maneuver, the acceleration changes in a deterministic manner. Thus, the white noise assumption associated with the process noise is violated and the filter develops a bias in the state estimates during maneuvers. The problem of tracking maneuvering targets with multiple sensors is illustrated through an example involving target motion in a single coordinate in which it is shown that with two sensors one can have (under certain conditions that include perfect alignment of the sensors) worse track performance than a single sensor. The Interacting Multiple Model (IMM) algorithm is applied to the illustrative example to demonstrate a potential solution to this problem of track filter performance.

92 citations


Journal ArticleDOI
01 Sep 1996
TL;DR: In this article, a detailed analysis of the Wigner and pseudo-Wigner distributions (PWDs) is presented, along with three-dimensional (3D) plots of 3D plots of Wigners.
Abstract: Time series data have been traditionally analyzed in either the time or the frequency domains. For signals with a time-varying frequency content, the combined time-frequency (TF) representations, based on the Cohen class of (generalized) Wigner distributions (WD's) offer a powerful analysis tool. Using them, it is possible to: (1) trace the time-evolution of the resonance features usually present in a standard sonar cross section (SCS), or in a radar cross section (RCS) and (2) extract target information that may be difficult to even notice in an ordinary SCS or RCS. After a brief review of the fundamental properties of the WD, we discuss ways to reduce or suppress the cross term interference that appears in the WD of multicomponent systems. These points are illustrated with a variety of three-dimensional (3-D) plots of Wigner and pseudo-Wigner distributions (PWD). The plots are all obtained from an extensive analysis we have made over the years of the resonance acoustic echoes backscattered by a variety of elastic shells submerged in water, when they are excited by various types of incident pressure waves, including the short pulses generated by explosive charges. We also review studies we have made of the echoes returned by conducting or dielectric targets in the atmosphere, when they are illuminated by broadband radar pings. These short incident pulses are used to analytically model the performance of ultrawide band (UWB) radars, often called impulse radars. A TF domain analysis of these impulse radar returns demonstrates their superior information content.

91 citations


Journal ArticleDOI
TL;DR: In this paper, the ability of a moving-mass roll control system to control the roll attitude and trajectory of a simple fixed-trim re-entry vehicle using a linear roll autopilot is investigated.
Abstract: The ability of a moving-mass roll control system to control the roll attitude and trajectory of a simple fixed-trim re-entry vehicle using a linear roll autopilot is investigated. The governing equations of motion of the coupled vehicle-moving-mass two-body system, which form the basis of the study, are presented and discussed. An analysis of these equations reveals that dynamic and aerodynamic cross-coupling is produced by the operation of this control system; however, some vehicle design techniques are employed to mitigate these effects. The mass effectiveness parameter, obtained through linearization of the moment equation, is shown to be the key system design parameter. The design of an optimal linear roll autopilot using modern state-space methods is presented in detail, along with an optimal-gain-vector scheduling function. A nonlinear seven-degree-of-freedom simulation of a typical mission profile trajectory demonstrates the ability of the linear autopilot to effectively control the vehicle's roll attitude and trajectory. Dynamic, aerodynamic, and inertial cross-coupling do not appear to significantly degrade the control system's response.

86 citations


Journal ArticleDOI
TL;DR: The utility of charge pumping to measure Si-SiO/sub 2/ interface trap density in irradiated four-terminal VDMOSFETs is demonstrated in this paper, where recombination of charge through interface traps in the neck region is measured in the drain.
Abstract: The utility of charge pumping to measure Si-SiO/sub 2/ interface trap density in irradiated four-terminal VDMOSFETs is demonstrated. A modification of the conventional charge pumping approach is employed, where recombination of charge through interface traps in the neck region is measured in the drain. Three components of drain current resulting from the charge pumping measurement are identified. When the device is properly biased, charge pumping current can be separated from the other components of drain current and modeled over a wide range of interface trap densities using standard charge pumping theory. When sources of error are accounted for, radiation-induced interface trap densities measured with charge pumping are in good quantitative agreement with those estimated with the midgap charge separation and subthreshold hump techniques.

67 citations


Journal ArticleDOI
TL;DR: In this paper, the root-mean-square (rms) miss distance of a proportional navigation (PN) homing missile against a target performing a sinusoidal weave maneuver is evaluated.
Abstract: The performance of a proportional navigation homing missile against a target performing a sinusoidal weave maneuver is evaluated. The missile's effectiveness is measured in terms of the root-mean-square miss distance over a set of engagements in which the initial phase of the target weave is uniformly distributed. Closed form solutions for the root-mean-square miss are derived for the case where the missile guidance system is modeled by a first-order lag and the lateral acceleration is unlimited. The analysis is then extended to include the effects of acceleration saturation and higher order missile dynamics. Comparisons are made between a first-order and a fifth-order guidance system, and the root-mean-square miss is determined numerically as a function of the interceptor's effective navigation gain, time constant and acceleration limit, and the target's weave amplitude and frequency. UTURE homing interceptor missiles will face new and unique challenges as the sophistication of the threat spectrum in- creases. Engagements against air targets can occur at both very low and very high altitudes, with the threats accidentally or intentionally performing weaving or spiraling maneuvers during their midcourse and terminal phases.1"4 The lateral displacement, acceleration ca- pability, and weave frequency of the target maneuver can greatly enhance the threat's ability to survive a counterattack. To counter this, the defensive missile must have sufficient lateral acceleration, guidance system time constant, and terminal homing time to achieve a high probability of intercept. Whereas the per- formance of the interceptor will be influenced by many scenario- dependent factors,5"8 a major consideration will be the fundamental response of the proportional navigation (PN) guidance system to the postulated target weave motion.9'10 In the general case, the target dynamics may involve arbitrary periodic motion in three dimensions. A useful starting point for analysis, however, is the response of the PN homing system to a single plane sinusoidal maneuver of constant amplitude and fre- quency. The phase angle of target weave, which is associated with initial conditions at the start of the missile's terminal guidance, can be treated as a random variable, uniformly distributed between 0 and 2n over a set of engagements. The missile's dynamics are approxi- mated by a simple first-order transfer function, and unlimited lateral acceleration capability is assumed. The miss distance can then be parameterized in terms of the effective PN navigation gain N, the missile time constant T, and the amplitude AT and frequency co of the target weave. This paper focuses on root-mean-square (rms) miss distance as a recommended measure of effectiveness in analyzing missile perfor- mance against weaving targets. This measure allows uncertainties in target phase characteristics to be accounted for in the terminal per- formance results. The weaving target problem was first addressed by Chadwick, 9 who determined analytical expressions for the rms miss distance of the single lag PN missile for values of N =2 and 3. Zarchan 10 employed adjoint theory and transfer function tech- niques to determine formulas for the peak miss distance against a weaving target for values of N between 3 and 6. The present paper derives general closed-form expressions for the rms miss distance against a sinusoidal target. New results are obtained for arbitrary

Journal ArticleDOI
TL;DR: In this article, the interaction between a growing and collapsing bubble and two types of compliant structures is explored numerically, where the fluid motion is modelled as a potential flow and computed using a boundary element method.

Journal ArticleDOI
TL;DR: The main contribution of this work is the development of a high-dimensional chaos control method that is effective, robust against noise, and easy to implement in experiment.
Abstract: The main contribution of this work is the development of a high-dimensional chaos control method that is effective, robust against noise, and easy to implement in experiment. Assuming no knowledge of the model equations, the method achieves control by stabilizing a desired unstable periodic orbit with any number of unstable directions, using small time-dependent perturbations of a single system parameter. Specifically, our major results are as follows. First, we derive explicit control laws for time series produced by discrete maps. Second, we show how to apply this control law to continuous-time problems by introducing straightforward ways to extract from a continuous-time series a discrete time series that measures the dynamics of some Poincar\'e map of the original system. Third, we illustrate our approach with two examples of high-dimensional ordinary differential equations, one autonomous and the other periodically driven. Fourth, we present the result on our successful control of chaos in a high-dimensional experimental system, demonstrating the viability of the method in practical applications.

Journal ArticleDOI
TL;DR: In this article, it was shown that the mixture of rare earth salts and phosphoric acid in aqueous or ethanolic media can form stable gels with high resistance to attack by water, absence of coloration upon exposure to gamma rays and a high index of refraction.
Abstract: Studies of the reactions between rare earth salts and phosphoric acid in aqueous or ethanolic media have shown that in both cases stable gels can be formed. Upon drying, gels prepared in aqueous environments yield macrocrystalline REPO4 products similar to those produced by conventional precipitation and drying. Gels prepared in ethanol, on the other hand, undergo dehydration to form dense microcrystalline products. This observation is based on optical and scanning electron microscopy, as well as on x-ray diffraction studies and infrared spectroscopy. These techniques, as well as differential thermal analysis, indicate that crystal growth of these products takes place around 600−700 °C. The composition of the dehydrated gels produced in both the aqueous and ethanolic systems corresponds to an orthophosphate structure. Other characteristics of the microcrystalline REPO4 products include high resistance to attack by water, absence of coloration upon exposure to gamma rays, and a high index of refraction.

Journal ArticleDOI
TL;DR: Two algorithms are developed for obtaining one-step fixed-lag smoothed estimates for Markovian switching systems by using an approximation that considers the models over the two most recent sampling periods, while the second one considers only the model over the most recently sampling period.
Abstract: Suboptimal approaches to the one-step fixed-lag smoothing problem for Markovian switching systems are examined in this paper. Two algorithms are developed for obtaining one-step fixed-lag smoothed estimates. The first algorithm is an approximation that considers the models over the two most recent sampling periods, while the second one considers only the models over the most recent sampling period. Simulation results are presented to compare the performances of these smoothing algorithms.

Journal ArticleDOI
TL;DR: In this article, thin-layer Navier-Stokes solutions are obtained for an incompressible laminar flow over a hemisphere-cylinder at 10°, 30° and 50° incidence to exhibit some three-dimensional separated flow characteristics.
Abstract: Thin-layer Navier–Stokes solutions are obtained for an incompressible laminar flow over a hemisphere–cylinder at 10°, 30° and 50° incidence to exhibit some three-dimensional separated flow characteristics. Some of the results are compared with a previous water-tunnel investigation for the same body geometry. Good agreement is found, even for some detailed features. Although the geometry is relatively simple, the separated flow surprisingly embraces a number of intricate structural characteristics unique to three-dimensional flows. Particularly noteworthy are the separation sequence at increasing incidence, tornado-like vortices, outward-spiralling vortices, limit cycles, coaxial counter-spiralling patterns and horseshoe vortex systems. Physical insights to these new features are offered.

Journal ArticleDOI
TL;DR: In this paper, the phase diagram for ammonium dinitramide (ADN) was determined using a high-temperature−high-pressure diamond anvil cell with optical polarizing light microscopy, Fourier transform infrared spectroscopy, laser-Raman spectrography, and energy dispersive X-ray diffraction.
Abstract: The pressure, temperature reaction phase diagram for ammonium dinitramide (ADN) was determined using a high-temperature−high-pressure diamond anvil cell with optical polarizing light microscopy, Fourier transform infrared spectroscopy, laser-Raman spectroscopy, and energy dispersive X-ray diffraction. The phase diagram was determined between ambient pressure and 10.0 GPa over the temperature range from −75 °C to decomposition temperatures, or 120 °C. The diagram delineates the melting curve for α-ADN, a reversible phase transition in α-ADN forming a new high-pressure monoclinic polymorph, β-ADN, and also identifies the pressure and temperature conditions at which a solid phase rearrangement occurs to form ammonium nitrate (AN) and N2O. Energy dispersive X-ray diffraction and Raman spectra were obtained for both α- and β-ADN as a function of pressure at room temperature.

Journal ArticleDOI
TL;DR: In this article, experimental observations and numerical simulations show that the impact energy of the test ion influences the single-event gate rupture (SEGR) failure thresholds of vertical power MOSFETs.
Abstract: For the first time, experimental observations and numerical simulations show that the impact energy of the test ion influences the single-event gate rupture (SEGR) failure thresholds of vertical power MOSFETs Current testing methodology may produce false hardness assurance

Proceedings ArticleDOI
13 May 1996
TL;DR: The alpha-stable distribution as mentioned in this paper is derived from the generalized central limit theorem and contains the Gaussian (or Rayleigh) distribution as a subset, and is shown to fit examples of ship RCS as well as sea clutter examples.
Abstract: The radar backscatter from complex sources, such as ships and ocean waves, can vary rapidly with target aspect or time. The radar cross section (RCS) of such targets is usually described in statistical terms using one of the many statistical models that are available. These models, however, tend to fit less well when the amplitude fluctuations begin to vary over wider extremes and become impulsive in nature. To better handle this condition, the alpha-stable distribution is shown to model RCS over a wide range of amplitudes. The alpha-stable distribution is derived from the generalized central limit theorem and contains the Gaussian (or Rayleigh) distribution as a subset. The alpha-stable distribution is shown to fit examples of ship RCS as well as sea clutter examples. The performance of various envelope detectors including the maximum likelihood detector for the alpha-stable distribution is shown for a low signal-to-noise (SNR) case.

Journal ArticleDOI
TL;DR: In this article, a Williams type of eigenfunction expansion approach is used to compute the local stress singularity representing a measure of the degree of inherent flaw sensitivity of unidirectional fiber reinforced composites subjected to compression.
Abstract: A Williams type of eigenfunction expansion approach is used to compute the local stress singularity representing a measure of the degree of inherent flaw sensitivity of unidirectional fiber reinforced composites subjected to compression. Previous experimental studies have qualitatively linked the formation of kink bands to the presence of fabrication defects, such as fiber misalignment. These local singular stress regions serve as the primary trigger mechanism for kink band propagation in 0°-plies. The present analysis also explains the previous test results relating to propagation of failure from a notch in a unidirectional composite under compression. Furthermore, the present investigation is the first to quantify, in the context of LEFM (linear elastic fracture mechanics), the sensitivity of these composites to inherent local flaws, such as fiber misalignments, and also shows the inadequacy of the conventional elastic micro-buckling type of analysis to fully explain the experimental results. Although b...

Journal ArticleDOI
TL;DR: In this paper, the authors considered the scattering of plane acoustic waves by spherical objects near a plane hard surface and used the method of images to predict the distorted sonar cross section of a hard spherical object near a hard flat bottom.
Abstract: We consider the scattering of plane acoustic waves by spherical objects near a plane hard surface. The angles of incidence are arbitrary and so are the distances of the objects from the hard boundary. We use the method of images. The final result for the sound field consists of four parts: the incident field and its reflection from the boundary, which are shown combined; the scattered field from the sphere, and that scattered by its image. These last two appear coupled since both sphere and image are repeatedly interacting with each other. The entire solution is referred to the center of the real sphere. This can be accomplished in an exact fashion by means of the addition theorems for spherical wave-functions. These theorems are taken from the atomic physics literature, where they are more frequently used. The required coupling coefficients, b/sub mn/, are obtained from the solution of an infinite linear complex system of transcendental equations with coefficients given by series. The system is suitably truncated to obtain numerical predictions for the form-functions by means of the Gauss-Seidel iteration method. Many calculations are displayed exhibiting the distortion that the proximity of the hard boundary causes on the free-space solution. The form-functions are graphed versus ka, for various values of the normalized separation D/spl equiv/d/a of the sphere from its image. They are also plotted versus the angle of observation, for fixed values of /spl Omega/=La and D. These plots are the exact benchmark curves against which the accuracy of approximate solutions, found by other methods, could be assessed. They could also serve to determine the distances above the bottom, beyond which the bottom effect could be neglected. This is an idealized model to predict the distorted sonar cross section of a hard spherical object near a hard flat bottom.

Journal ArticleDOI
TL;DR: In this article, the fracture and deformation behaviors of several product forms produced from mechanically alloyed (MA) aluminum alloys 9052 and 905XL were studied, and the main operative strengthening mechanism is strengthening due to the submicron grain size.
Abstract: The fracture and deformation behaviors of several product forms produced from mechanically alloyed (MA) aluminum alloys 9052 and 905XL were studied. The main operative strengthening mechanism is strengthening due to the submicron grain size. Ductility and toughness were found to be controlled by the morphology of the prior particle boundaries. We propose that the work-hardening behavior of these MA alloys is similar to the behavior exhibited by a deformed fcc alloy that (a) contains rigid barriers to dislocation motion, (b) deforms by wavy slip, and (c) forms a cell substructure upon deformation.

Journal ArticleDOI
TL;DR: In this article, nanosecond and picosecond laser irradiations have been used to study the decomposition of ammonium perchlorate (NH4ClO4) crystals, a main component of propellants.
Abstract: Nanosecond and picosecond laser irradiations have been used to study the decomposition of ammonium perchlorate (NH4ClO4) crystals, a main component of propellants. Chlorate (NH4ClO3) decomposition product was detected via X-ray photoelectron spectroscopy. The decomposition is initiated amid associated mechanical deformations and microcracking processes occurring on a time scale commensurate with actual frequencies of energetic crystal decompositions pertinent to propellant combustion. Optical, scanning electron and atomic force microscopy methods have been applied to characterization of the laser-damage zones. Individual initiation or residual “hot spot” sites have been detected in the electron and atomic force microscope images, and are related to the cracking behaviour of the perchlorate allotropic phases. Evidence of the 240°C orthorhombic to rock-salt type cubic transformation was obtained in nanosecond laser irradiations through a remnant microstructure of ultrafine cracks whose intersection points marked an array of decomposition sites. A dislocation model description is given for the connected cracking and decomposition site observations.

Journal ArticleDOI
01 May 1996
TL;DR: In this paper, a linear discriminant classifier is implemented to detect localized defects on a roller and the outer race of a bearing, and the proposed scheme is effective in bearing defect detection and sensitive to incipient defects.
Abstract: For automatic detection and diagnosis of localized defects in rolling element bearings, bicoherence spectra are used to derive features that signify the condition of a bearing. These features quantitatively describe the degree of phase correlation among any three harmonics of bearing characteristic defect frequencies. Employing these features, a linear discriminant classifier is implemented to detect localized defects on a roller and the outer race of a bearing. Experimental results show that the proposed scheme is effective in bearing defect detection and sensitive to incipient defects.

Journal ArticleDOI
TL;DR: In this article, the heavy-ion fluence required to induce SEGR in power MOSFETs is measured as a function of the drain bias, V/sub DS/, and as a result, the SEGR-voltage threshold is abrupt.
Abstract: The heavy-ion fluence required to induce Single-Event Gate Rupture (SEGR) in power MOSFETs is measured as a function of the drain bias, V/sub DS/, and as a function of the gate bias, V/sub GS/. These experiments reveal the abrupt nature of the SEGR-voltage threshold. In addition, the concepts of cross-section, threshold, and saturation in the SEGR phenomenon are introduced. This experimental technique provides a convenient method to quantify heavy-ion effects in power MOSFETs.

Journal ArticleDOI
TL;DR: In this article, a photocatalytic method for selective oxidation of the airborne nitroglycerine (NG), in the presence of ethanol and acetone vapors at high concentrations (exceeding 1% by volume), was described.

Journal ArticleDOI
TL;DR: In this paper, the single event-gate-rupture cross-section is measured as a function of drain-source and gate-source bias for some n-channel power MOSFETs.
Abstract: The single-event-gate-rupture cross-section is measured as a function of drain-source and gate-source bias for some n-channel power MOSFETs. The experimental techniques are explained, and the results are interpreted with the help of two-dimensional computer modeling.

Journal ArticleDOI
TL;DR: In this article, SEGR cross-sectional area curves are inferred for eighteen different device types of radiation-hardened power MOSFETs and compared to demonstrate the technology's insensitivity to die size, rated blocking voltage, channel conductivity, and temperature.
Abstract: SEGR response curves are presented for eighteen different device types of radiation-hardened power MOSFETs. Comparisons are made to demonstrate the technology's insensitivity to die size, rated blocking voltage, channel conductivity, and temperature. From this data, SEGR cross-sectional area curves are inferred.

Proceedings ArticleDOI
31 May 1996
TL;DR: Preliminary results show that the COBRA system, coupled with these algorithms, meets the required minefield detection performance goals and is ideal for detecting a wide variety of mines with unknown or changing spectral signatures.
Abstract: The Coastal Systems Station (CSS) at Panama City, FL is developing an airborne multispectral sensor system which flies on an unmanned aerial vehicle for detecting mines in a coastal environment. This system is called the Coastal Battlefield Reconnaissance and Analysis (COBRA) system and has successfully completed preliminary developmental testing (DT-0). For this program, the Environmental Research Institute of Michigan (ERIM) developed a fieldable ground station including integrated aircraft tracking, real-time sensor data analysis, and a post processor testbed for developing and evaluating mine and minefield detection algorithms. A fully adaptive multispectral Constant False Alarm Rate mine detection algorithm was implemented in the post-processor by ERIM, along with patterned and scatterable minefield detection algorithms developed by CSS. The algorithms do not require prior knowledge of mine spectral signatures and thus are ideal for detecting a wide variety of mines with unknown or changing spectral signatures. COBRA DT-0 testing has been performed on actual minefields deployed at coastal and inland test sites. Preliminary results show that the COBRA system, coupled with these algorithms, meets the required minefield detection performance goals. This paper reviews the algorithm theory and implementation, overviews the ground station design, and presents minefield detection results from actual minefield imagery collected over realistic scenes during DT-0 testing.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Proceedings ArticleDOI
19 Aug 1996
TL;DR: In this paper, an impedance versus frequency characterization of a 60 Hz power distribution system has been performed from 30 Hz to 1 MHz, using both empirical and theoretical aspects utilizing transmission line theory.
Abstract: An impedance versus frequency characterization of a 60 Hz power distribution system has been performed from 30 Hz to 1 MHz. The impedance characterization involves both empirical and theoretical aspects utilizing transmission line theory. The characterization yielded transmission line attributes that determine the power distribution system's performance for auxiliary functions such as data propagation. Potential applications of the characterization include analyzing the applicability of a residential power distribution system for data communications.