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Articles 116281 - 116310 of 194089

Full-Text Articles in Engineering

Suicide Bomber Detection Using Millimeter-Wave Radar, Richard Sullivan, Morgan Galaznik, Jose Ángel Martinez-Lorenzo, Carey M. Rappaport Apr 2012

Suicide Bomber Detection Using Millimeter-Wave Radar, Richard Sullivan, Morgan Galaznik, Jose Ángel Martinez-Lorenzo, Carey M. Rappaport

Carey Rappaport

Amidst the manifold threats currently afflicting public welfare, that of body-worn explosives is significant if not altogether paramount. Commonly referred to as ""suicide bombers,"" the bearers of body-worn, improvised explosive devices (IEDs) enter crowded public areas in order to detonate the IDE, inflicting lethal damage to themselves and surrounding individuals. Constructed of non-standard parts and veiled under layers of clothing, these body-worn IEDs go frequently undetected. The aim of this research is to examine the feasibility of using millimeter-wave (MMW) radar to detect body-worn IEDs at distances up to 50 meters. In order to achieve a beamwidth capable of illuminating …

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Reflector Antenna Discrete Distortion Determination : An Iterative-Field-Matrix Solution, José Ángel Martinez-Lorenzo, Carey M. Rappaport Apr 2012

Reflector Antenna Discrete Distortion Determination : An Iterative-Field-Matrix Solution, José Ángel Martinez-Lorenzo, Carey M. Rappaport

Carey Rappaport

The idealized shapes of satellite reflector antennas are often distorted once they are placed in orbit. The performance of such antennas can be improved by identifying the locations and amount of their surface distortions and then by correcting them using active surface distortion or array feeding. This work presents a method to determine the required discrete surface distortions to correct errors. The algorithm starts by discretizing the entire reflector surface into triangular patches, then by finding a linear relationship between the local distortion and the difference of the distorted and undistorted farfields patterns. A linear system of equations with the …

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Bimodal Detection Of Underground Contamination In Two Dimensional Systems, Maria Fernanda Serrano G., Ingrid Padilla, Rafael Rodriguez Solis, Carey Rappaport Apr 2012

Bimodal Detection Of Underground Contamination In Two Dimensional Systems, Maria Fernanda Serrano G., Ingrid Padilla, Rafael Rodriguez Solis, Carey Rappaport

Carey Rappaport

An environmental issue that has reached interest in the academic and industry is groundwater contamination. Moreover, government agencies are concerned, for example, about the widespread of dense non-aqueous phase liquids (DNAPLs) in the underground due to incorrect disposal of this substance. Over the last five years we have done a great effort to enhance Cross Well Radar as a technology for detection of compounds which can be used to predict the mobility and persistence of chemicals in the unsaturated near surface. Image acquisition and processing has also been applied for contaminant detection and monitoring. In this poster, we describe a …

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Experimental Validation Of A Numerical Forward Model For Tunnel Detection Using Cross-Borehole Radar, Arvin Farid, Jose A. Martinez-Lorenzo, Akram N. Alshawabkeh, Carey M. Rappaport Apr 2012

Experimental Validation Of A Numerical Forward Model For Tunnel Detection Using Cross-Borehole Radar, Arvin Farid, Jose A. Martinez-Lorenzo, Akram N. Alshawabkeh, Carey M. Rappaport

Carey Rappaport

The goal of this research is to develop an experimentally validated twodimensional (2D) finite difference frequency domain (FDFD) numerical forward model to study the potential of radar-based tunnel detection. Tunnel detection has become a subject of interest to the nation due to the use of tunnels by illegal immigrants, smugglers, prisoners, assailants, and terrorists. These concerns call for research to nondestructively detect, localize, and monitor tunnels. Nondestructive detection requires robust image reconstruction and inverse models, which in turn need robust forward models. Cross-Well Radar (CWR) modality is used for experimentation to avoid soil-air interface roughness. CWR is not a versatile …

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The Semi-Analytic Mode Matching (Samm) Algorithm For Efficient Computation Of Near Field Scattering From Borehole Antennas In Lossy Ground, Ann W. Morgenthaler, He Zhan, Carey M. Rappaport Apr 2012

The Semi-Analytic Mode Matching (Samm) Algorithm For Efficient Computation Of Near Field Scattering From Borehole Antennas In Lossy Ground, Ann W. Morgenthaler, He Zhan, Carey M. Rappaport

Carey Rappaport

The 3D semi-analytic mode matching (SAMM) algorithm is used to determine nearfield scattering from realistic targets buried in lossy, possibly rough soil where the source is a dipole placed within a borehole in the ground. SAMM has been successfully implemented as a forward model for inverse scattering algorithms, and can be used as a GPR design tool which is both cheaper and more efficient than experimentation. SAMM can be (and has been) used for geophysical, medical, and biological applications, including mine detection, pollution detection, microwave tumor detection. Other possible applications that could utilize SAMM are cell structure characterization, wall penetrating …

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Fdtd Simulation Of A Confocal Microscope Using A Theta Line Scan, Blair Simon, Charles Dimarzio, Milind Rajadhyaksha, Carey Rappaport Apr 2012

Fdtd Simulation Of A Confocal Microscope Using A Theta Line Scan, Blair Simon, Charles Dimarzio, Milind Rajadhyaksha, Carey Rappaport

Carey Rappaport

We describe a 2-D computational model of the optical propagation in human skin from a confocal reflectance theta microscope. As an effect of decreasing the size of the microscope so that it is more clinically useful, the usual point source and detector with a raster scan is changed to a line source with a 1-D array detector. Because there is only one dimension of scanning, the microscope is confocal in one direction, but not in the other, however, this results in additional localized decreases in signal. We hypothesize that these result from the interaction of the bi-static imaging configuration with …

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Computational Modeling And Analysis Of Radar Scattering By Metallic Body-Worn Explosive Devices Covered With Wrinkled Clothing, Amanda Angell, Carey Rappaport Apr 2012

Computational Modeling And Analysis Of Radar Scattering By Metallic Body-Worn Explosive Devices Covered With Wrinkled Clothing, Amanda Angell, Carey Rappaport

Carey Rappaport

In this study, we address the problem of detecting bodyworn improvised explosive devices (IEDs) from a safe distance using radar. We have used a finite difference frequency domain (FDFD) model to simulate the radar signature of a typical scenario for body-worn IEDs, and have analyzed wrinkled clothing as a possible source of clutter. Our analysis shows distinct characteristics of the IED backscattered farfield signal, with no significant clutter added when the metallic IED is covered by wrinkled clothing.

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Introducing The Nufdtd Software Package, Seth Baum, Carey Rappaport Apr 2012

Introducing The Nufdtd Software Package, Seth Baum, Carey Rappaport

Carey Rappaport

FDTD is a successful technique for numerically simulating electromagnetic wave propagation. Our group at Northeastern does research to improve the performance of various aspects of the technique and has built these improvements into its own FDTD software package, "NUFDTD," making the code in some ways more powerful than those available commercially. These improvements include a frequency dispersion model and handling of stratified layers. Recent work (Mr. Baum's Masters thesis) has built this code into a user-friendly software package. This package is currently available via free download and is ready for use by both the academic community and the commercial sector.

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Simulating Gpr For Diagnosis Of Civil Infrastructure, Laura Carey, Kimberly Belli, Carey M. Rappaport, Sara J. Wadia-Fascetti Apr 2012

Simulating Gpr For Diagnosis Of Civil Infrastructure, Laura Carey, Kimberly Belli, Carey M. Rappaport, Sara J. Wadia-Fascetti

Carey Rappaport

At the present, a large proportion of our nation's bridges and roadways are falling into disrepair. About 27.5% of U.S. bridges are structurally deficient or functionally obsolete (ASCE, 2001, 2003). Nondestructive testing methods, such as GPR, are becoming more and more important in diagnosing the condition of such concrete structures. GPR is a high-resolution electromagnetic technique used to investigate the immediate subsurface of the earth, building materials, roads, and bridges. This poster shows my work in GPR modeling during a summer undergraduate experience through CenSSIS. A specialized MATLAB toolbox designed by Kim Belli created all data presented here. The use …

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Comparison And Application In 3d Matlab-Based Finite-Difference Frequency-Domain Method, Qiuzhao Dong, He Zhan, Ann Morgenthaler, Carey Rappaport Apr 2012

Comparison And Application In 3d Matlab-Based Finite-Difference Frequency-Domain Method, Qiuzhao Dong, He Zhan, Ann Morgenthaler, Carey Rappaport

Carey Rappaport

The FDFD electromagnetic model computes wave scattering by directly discretizing Maxwell's equations along with specifying the material characteristics in the scattering volume. No boundary conditions are need except for the outer grid termination absorbing boundary. We use a sparse matrix Matlab code with generalized minimum residue (GMRES) Krylov subspace iterative method to solve the large sparse matrix equation, along with the Perfectly Matched Layer (PML) absorbing boundary condition. The PML conductivity profile employs the empirical optimal value from[4-6]. The sparse Matlab-based model is about 100 times faster than a previous Fortran-based code implemented on the same Alpha-class supercomputer. The 3D …

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Validating Four-Zeros 2d Fdtd Model, Maryam Jalalinia, Carey M. Rappaport Apr 2012

Validating Four-Zeros 2d Fdtd Model, Maryam Jalalinia, Carey M. Rappaport

Carey Rappaport

In this work we model wave propagation in two-dimensional dispersive medium using FDTD (Finite Difference Time Domain) method. For a lossy, dispersive medium, it is significant to model the wave velocity and attenuation over a wide RF bandwidth with a simple and efficient model. Using a four-zeros single-pole rational function of the Z-transform variable (Z = exp(j??t)) to model conductivity with constant real dielectric constant, we generate a discretized time domain equation which matches measured values over more than two decades of frequency. The simulations show that there is a good agreement between measureed and modeled propagation constant and attenuation …

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Tunnel Detection Using Cross Borehole Radar, Clay Kurison, Arvin M. Farid, Akram N. Alshawabkeh, Carey M. Rappaport Apr 2012

Tunnel Detection Using Cross Borehole Radar, Clay Kurison, Arvin M. Farid, Akram N. Alshawabkeh, Carey M. Rappaport

Carey Rappaport

Shallow tunnels present both military and homeland security threats. Smugglers with intentions of avoiding border security have turned tunnels into transit routes for trafficking weapons, people, drugs and other illegal materials. Shallow tunnels are also used by prisoners to escape prisons. While drug and human trafficking have long been border concerns, the threat of international terrorism has transformed the effort to detect tunnels into a national security priority. Imminent threats include assailants entering military fortifications by burrowing under buildings, detonation of high grade explosives from foundations of high security facilities, and high level prisoners escaping detention centers through tunnels. Real-time …

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Hardware Implementation Of Image Space Reconstruction Algorithm Using Fpgas, Javier Morales, Nayda Santiago, Miriam Leeser, Alejandro Fernandez Apr 2012

Hardware Implementation Of Image Space Reconstruction Algorithm Using Fpgas, Javier Morales, Nayda Santiago, Miriam Leeser, Alejandro Fernandez

Miriam Leeser

The Image Space Reconstruction Algorithm (ISRA) has been used in hyperspectral imaging applications to monitor changes in the environment and specifically, changes in coral reef, mangrove, and sand in coastal areas. This algorithm is one of a set of iterative methods used in the hyperspectral imaging area to estimate abundance. However, ISRA is highly computational, making it difficult to obtain results in a timely manner. We present the use of specialized hardware in the implementation of this algorithm, specifically the use of VHDL and FPGAs. The implementation of ISRA algorithm has been divided into hardware and software units. The hardware …

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Floating-Point Divide And Square Root For Efficient Fpga Implementation Of Image And Signal Processing Algorithms, Xiaojun Wang, Miriam Leeser Apr 2012

Floating-Point Divide And Square Root For Efficient Fpga Implementation Of Image And Signal Processing Algorithms, Xiaojun Wang, Miriam Leeser

Miriam Leeser

Division and square root are important operations in any high performance signal processing applications. We have implemented floating point division and square root based on Taylor series for the variable precision floating point library developed at the Reconfigurable Computing Laboratory at Northeastern. Our result shows that they are very well suited to FPGA implementations, and lead to a good tradeoff of area and latency. We implemented a floating-point K-means clustering algorithm and applied it to multispectral satellite images. The mean update is moved from host to FPGA hardware with the new fp_div module to reduce the communication between host and …

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Wave-Based Modeling, Highlighting Underground Sensing And Imaging, Carey Rappaport, Sara Wadia-Fascetti, Miriam Leeser Apr 2012

Wave-Based Modeling, Highlighting Underground Sensing And Imaging, Carey Rappaport, Sara Wadia-Fascetti, Miriam Leeser

Miriam Leeser

No abstract provided.

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Field Programmable Gate Arrays To Accelerate Sub-Surface Imaging Problems, Miriam Leeser Apr 2012

Field Programmable Gate Arrays To Accelerate Sub-Surface Imaging Problems, Miriam Leeser

Miriam Leeser

No abstract provided.

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Phase Unwrapping Using Reconfigurable Hardware, Sherman Braganza, Miriam Leeser, W. C. Warger Ii, C. M. Warner, C. A. Dimarzio Apr 2012

Phase Unwrapping Using Reconfigurable Hardware, Sherman Braganza, Miriam Leeser, W. C. Warger Ii, C. M. Warner, C. A. Dimarzio

Miriam Leeser

The most computationally intensive part of the minimum LP Norm phase unwrapping algorithm[1] (its kernel) is the 2D Discrete Cosine Transform(DCT) that computes the variable p in the equation Qp=c using the Preconditioned Conjugate Gradient (PCG) method. The separability of the DCT means that the 2D transform can be decomposed into a series of 1D DCTS that compute the transforms of the rows followed by the transforms of the columns. Furthermore, the DCT can be expressed in terms of a Fast Fourier Transform (FFT), which allows the hardware implementation to use a pre-designed FFT core. This poster presents a design …

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Floating Point Division And Square Root And The Applications, Xiaojun Wang, Miriam Leeser Apr 2012

Floating Point Division And Square Root And The Applications, Xiaojun Wang, Miriam Leeser

Miriam Leeser

Division and square root are important operations in many high performance signal processing applications. We have implemented floating point division and square root based on Taylor series for the variable precision floating point library developed at the Reconfigurable Computing Laboratory at Northeastern. Our result shows that they are very well suited to FPGA implementations, and lead to a good tradeoff of area and latency. We implemented a floating-point K-means clustering algorithm and applied it to multispectral satellite images. The mean update is moved from host to FPGA hardware with the new fp_div module to reduce the communication between host and …

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Fdtd Simulation Of A Confocal Microscope Using A Theta Line Scan, Blair Simon, Charles Dimarzio, Milind Rajadhyaksha, Carey Rappaport Apr 2012

Fdtd Simulation Of A Confocal Microscope Using A Theta Line Scan, Blair Simon, Charles Dimarzio, Milind Rajadhyaksha, Carey Rappaport

Charles A. DiMarzio

We describe a 2-D computational model of the optical propagation in human skin from a confocal reflectance theta microscope. As an effect of decreasing the size of the microscope so that it is more clinically useful, the usual point source and detector with a raster scan is changed to a line source with a 1-D array detector. Because there is only one dimension of scanning, the microscope is confocal in one direction, but not in the other, however, this results in additional localized decreases in signal. We hypothesize that these result from the interaction of the bi-static imaging configuration with …

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Phase Unwrapping Using Reconfigurable Hardware, Sherman Braganza, Miriam Leeser, W. C. Warger Ii, C. M. Warner, C. A. Dimarzio Apr 2012

Phase Unwrapping Using Reconfigurable Hardware, Sherman Braganza, Miriam Leeser, W. C. Warger Ii, C. M. Warner, C. A. Dimarzio

Charles A. DiMarzio

The most computationally intensive part of the minimum LP Norm phase unwrapping algorithm[1] (its kernel) is the 2D Discrete Cosine Transform(DCT) that computes the variable p in the equation Qp=c using the Preconditioned Conjugate Gradient (PCG) method. The separability of the DCT means that the 2D transform can be decomposed into a series of 1D DCTS that compute the transforms of the rows followed by the transforms of the columns. Furthermore, the DCT can be expressed in terms of a Fast Fourier Transform (FFT), which allows the hardware implementation to use a pre-designed FFT core. This poster presents a design …

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Using Diffuse Optical Tomography With Acoustic Photonic Imaging, Blair Simon, Charles A. Dimarzio Apr 2012

Using Diffuse Optical Tomography With Acoustic Photonic Imaging, Blair Simon, Charles A. Dimarzio

Charles A. DiMarzio

The goal of this work is to provide useful information about arthritic joints using a combination of light and ultrasound. Both light and sound have the advantages of being noninvasive, nontoxic, and non-ionizing. Light has the advantage of generating a spectroscopic view of a specific volume of soft tissue. The disadvantage of imaging with light in tissue is the poor resolution in scattering media while the disadvantage of imaging with ultrasound is that there is poor contrast imaging contrast in soft tissue. To mitigate these disadvantages the use of an Acoustic Photonic Imaging (API) system is employed. Modeling the microscopic …

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Improving The Data Acquisition Of The Dual-Wedge Confocal Microscope, Stephen A. Guerrera, William C. Wargar Ii, Charles A. Dimarzio Apr 2012

Improving The Data Acquisition Of The Dual-Wedge Confocal Microscope, Stephen A. Guerrera, William C. Wargar Ii, Charles A. Dimarzio

Charles A. DiMarzio

A new method of generating images from the dual-wedge confocal microscope was developed. The previous method of data acquisition resulted in data rates of 100Hz. In addition, many data points were visited multiple times, while others were never visited. This caused the acquisition of a single frame to take more than half an hour. For collecting images of excised skin tissue to characterize the microscope, this is a major issue, as the shape of the sample changes over time. To remedy this problem, a National Instruments Data Acquisition card was purchased, and signal conditioning circuitry was created to increase the …

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Component Extraction From Crm Skin Images, Sol M. Cruz Rivera, Vidya Manian, Charles A. Dimarzio Apr 2012

Component Extraction From Crm Skin Images, Sol M. Cruz Rivera, Vidya Manian, Charles A. Dimarzio

Charles A. DiMarzio

Confocal Reflectance Microscope images the skin in 4 dimensions. The third and fourth dimensions being the wavelength and the depth, respectively. We compare traditional methods with new techniques for component separation. The components from the skin images are cell/nuclei, mitochondria, melanin, organelles and other minor components. The spectral unmixing method N-finder is used to extract end members. The results of this method will be compared with ICA methods that will be developed for the 4-dimensional data. The components and their concentrations (abundances) will be output from these methods.

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Photo-Thermal Coherent Confocal Microscope, Sean Sullivan, Charles Dimarzio Apr 2012

Photo-Thermal Coherent Confocal Microscope, Sean Sullivan, Charles Dimarzio

Charles A. DiMarzio

Confocal microscopy has been shown to be useful in imaging skin slightly below the junction of the dermis and epidermis. However, the depth of imaging is a significant limitation. We present a novel concept designed both to improve the depth of penetration and to increase the information content of images obtained with a reflectance confocal microscope. Using an approach similar to optoacoustics, we plan to explore the use of laser heating to generate tissue expansion, which will be measured by the microscope. The microscope will incorporate a pulsed heating laser along the same optical path as the imaging laser in …

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Compact Dual Wedge Point Scanning Confocal Reflectance Microscope, William C. Warger Ii, Stephen A. Guerrera, Charles A. Dimarzio Apr 2012

Compact Dual Wedge Point Scanning Confocal Reflectance Microscope, William C. Warger Ii, Stephen A. Guerrera, Charles A. Dimarzio

Charles A. DiMarzio

Confocal reflectance microscopy has been shown to provide optical sectioning and resolution sufficient to provide useful information about skin to a depth below the epidermis. However, existing instruments are large and expensive, because of the need for fast twodimensional scanning in the pupil, and the associated relay optics. A more compact scanning system could lead to an affordable hand-held instrument for in vivo imaging. Several approaches are being considered with different advantages and disadvantages. Here we report one approach that incorporates a dual-wedge scanner within a point-scanning configuration. The dual-wedge scanner is implemented by replacing the two scanning mirrors and …

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Multi-Spectral Reflectance Confocal Microscopy On Skin, Tianchen Shi, Charles Dimarzio Apr 2012

Multi-Spectral Reflectance Confocal Microscopy On Skin, Tianchen Shi, Charles Dimarzio

Charles A. DiMarzio

Reflectance confocal microscopy is a powerful in-vivo modality for imaging superficial layers of biological tissue, especially for human skin. Three dimensional imaging capability enables confocal microscopy to resolve structures of upper skin layer cells. However, sub-celluar structure and corresponding functional organelles play more important parts in skin diseases diagnosis and monitoring. We present a new multi-spectral reflectance confocal microscopy to achieve sub-celluar functional imaging in skin by utilizing our unique Keck multi-modality microscope. Spectral information and a modified Mie scattering model are incorporated to identify distribution of melanin and mitochondria in cells. Ex-vivo and phantom experimental results are presented. Further …

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A New Approximate Model For Microscopy Imaging, Heidy Sierra, Dana Brooks, Charles Dimarzio Apr 2012

A New Approximate Model For Microscopy Imaging, Heidy Sierra, Dana Brooks, Charles Dimarzio

Charles A. DiMarzio

There has been increasing interest in recent years in techniques for microscopic examination of optically thick transparent objects. A number of phase imaging modalities have been developed to address this need. If a stack of images is acquired through focusing, the image at a given focal plane is contaminated by out-of-focus information coming from other planes [1]. There is a need to develop 3D imaging models for phase microscopes that will allow deconvolution, or more generally inverse reconstruction, techniques to be developed. Thus there is a need for an image formation model for phase microscopy that is able to maintain …

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Building Brains For Bodies, Lynn Stein, Rodney Brooks Apr 2012

Building Brains For Bodies, Lynn Stein, Rodney Brooks

Lynn Andrea Stein

We describe a project to capitalize on newly available levels of computational resources in order to understand human cognition. We are building an integrated physical system including vision, sound input and output, and dextrous manipulation, all controlled by a continuously operating large scale parallel MIMD computer. The resulting system will learn to "think" by building on its bodily experiences to accomplish progressively more abstract tasks. Past experience suggests that in attempting to build such an integrated system we will have to fundamentally change the way artificial intelligence, cognitive science, linguistics, and philosophy think about the organization ofintelligence. We expect to …

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Skeptical Inheritance: Computing The Intersection Of Credulous Extensions, Lynn Stein Apr 2012

Skeptical Inheritance: Computing The Intersection Of Credulous Extensions, Lynn Stein

Lynn Andrea Stein

Ideally skeptical inheritance supports exactly those inferences true in every credulous extension of an inheritance hierarchy. We provide a formal definition of ideally skeptical inheritance. We show that two path-based approaches fail to capture ideally skeptical inheritance, and that there are inheritance hierarchies for which there are more always-true inferences than always-supported paths. We describe an ATMS-like scheme that computes ideally skeptical inheritance and represents hierarchical dependencies using a limited form of Boolean satisfiability. Finally, we demonstrate a preemption (specificity) strategy for which ideally skeptical inheritance is polynomial time computable.

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Challenging The Computational Metaphor: Implications For How We Think, Lynn Stein Apr 2012

Challenging The Computational Metaphor: Implications For How We Think, Lynn Stein

Lynn Andrea Stein

This paper explores the role of the traditional computational metaphor in our thinking as computer scientists, its influence on epistemological styles, and its implications for our understanding of cognition. It proposes to replace the conventional metaphor a sequence of steps with the notion of a community of interacting entities, and examines the ramifications of such a shift on these various ways in which we think.

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