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1072 full-text articles. Page 7 of 33.

Machine Learning Through Mimicry And Association, Nickolas S. Holcomb 2016 Georgia Southern University

Machine Learning Through Mimicry And Association, Nickolas S. Holcomb

University Honors Program Theses

Adaptability is a key missing features that has impeded the growth of assistive robotics. In the traditional model, all actions must be explicitly coded by a skilled programmer familiar with the hardware. This project explores a method of teaching a webcam equipped arm type robot new primitive movement using visual demonstrations.


Mean-Field-Analysis Of Coding Versus Replication In Cloud Storage Systems, Bin Li, Aditya Ramamoorthy, R. Srikant 2016 University of Illinois at Urbana-Champaign

Mean-Field-Analysis Of Coding Versus Replication In Cloud Storage Systems, Bin Li, Aditya Ramamoorthy, R. Srikant

Electrical and Computer Engineering Conference Papers, Posters and Presentations

We study cloud-storage systems with a very large number of files stored in a very large number of servers. In such systems, files are either replicated or coded to ensure reliability, i.e., file recovery from server failures. This redundancy in storage can further be exploited to improve system performance (mean file access delay) through appropriate load-balancing (routing) schemes. However, it is unclear whether coding or replication is better from a system performance perspective since the corresponding queueing analysis of such systems is, in general, quite difficult except for the trivial case when the system load asymptotically tends to zero ...


Coded Caching With Low Subpacketization Levels, Li Tang, Aditya Ramamoorthy 2016 Iowa State University

Coded Caching With Low Subpacketization Levels, Li Tang, Aditya Ramamoorthy

Electrical and Computer Engineering Conference Papers, Posters and Presentations

Caching is popular technique in content delivery networks that allows for reductions in transmission rates from the content-hosting server to the end users. Coded caching is a generalization of conventional caching that considers the possibility of coding in the caches and transmitting coded signals from the server. Prior results in this area demonstrate that huge reductions in transmission rates are possible and this makes coded caching an attractive option for the next generation of content-delivery networks. However, these results require that each file hosted in the server be partitioned into a large number (i.e., the subpacketization level) of non- ...


Degrees Of Freedom Region Of Wireless X Networks Based On Real Interference Alignment, Mahdi Zamanighomi, Zhengdao Wang 2016 Stanford University

Degrees Of Freedom Region Of Wireless X Networks Based On Real Interference Alignment, Mahdi Zamanighomi, Zhengdao Wang

Electrical and Computer Engineering Publications

We first consider a single hop wireless X network with K transmitters and J receivers, all with a single antenna. Each transmitter conveys an independent message for each receiver. The channel is assumed to have constant coefficients. We develop an interference alignment scheme for this setup and derive an achievable degrees of freedom (DoF) region. We show that in some cases, the derived region meets a previous outer bound, and hence, is the (exact) DoF region. For our achievability schemes, we divide each message into streams and use real interference alignment on the streams. Several previous results on the DoF ...


Many Access For Small Packets Based On Precoding And Sparsity-Aware Recovery, Ronggui Xie, Huarui Yin, Xiaohui Chen, Zhengdao Wang 2016 Chinese Academy of Sciences

Many Access For Small Packets Based On Precoding And Sparsity-Aware Recovery, Ronggui Xie, Huarui Yin, Xiaohui Chen, Zhengdao Wang

Electrical and Computer Engineering Publications

Modern mobile terminals produce massive small data packets. For these short-length packets, it is inefficient to follow the current multiple access schemes to allocate transmission resources due to heavy signaling overhead. We propose a non-orthogonal many-access scheme that is well suited for the future communication systems equipped with many receive antennas. The system is modeled as having a block-sparsity pattern with unknown sparsity level (i.e., unknown number of transmitted messages). Block precoding is employed at each single-antenna transmitter to enable the simultaneous transmissions of many users. The number of simultaneously served active users is allowed to be even more ...


The Effects Of Frequency-Dependent Amplitude On The Time-Reversed Lamb Wave Based Baseline-Free Damage Detection, Liang Zeng, Jing Lin, Zhi Luo, Fei Gao 2016 Xi'an Jiaotong University

The Effects Of Frequency-Dependent Amplitude On The Time-Reversed Lamb Wave Based Baseline-Free Damage Detection, Liang Zeng, Jing Lin, Zhi Luo, Fei Gao

Review of Progress in Quantitative Nondestructive Evaluation

Time reversal is the process that a response signal recorded at a receiver location is reversed in time and emitted back to the original source transducer. In the absence of any damage, theoretically the main wave packet of the reconstructed signal could exactly resemble the original input wave form. However, since the amplitude response of Lamb wave mode is generally frequency dependent, the reconstruction is not perfect. In this study, the influences of the frequency-dependent amplitude to the spectrum of the reconstructed signal is investigated. The results show that the peak frequency shifts and the bandwidth varies due to the ...


Feasibility And Reliability Of Grain Noise Suppression In Monitoring Highly Scattering Materials Using Baseline Subtraction, Yuan Liu, Chang Liu, Peter Cawley 2016 Imperial College London

Feasibility And Reliability Of Grain Noise Suppression In Monitoring Highly Scattering Materials Using Baseline Subtraction, Yuan Liu, Chang Liu, Peter Cawley

Review of Progress in Quantitative Nondestructive Evaluation

This paper studies the feasibility and reliability of using the baseline subtraction method to suppress grain noise in monitoring highly scattering materials. Monitoring is usually done with permanently installed sensors but this is not always possible and here we investigate the feasibility of subtracting A-scans extracted from repeat C-scans. It is important that the transducer standoff and angle relative to the test piece are set consistently in the repeat scans and the influence of errors in these settings has been investigated. The successive C-scans can be registered by cross correlation and the effect of errors in the registration is illustrated ...


A Novel Method For Ultrasonic Imaging Of Flaws In Coarse Grain Austenitic Stainless Steels, Govind Kumar Sharma, Purnachandra Rao Bhagi 2016 Indira Gandhi Centre for Atomic Research

A Novel Method For Ultrasonic Imaging Of Flaws In Coarse Grain Austenitic Stainless Steels, Govind Kumar Sharma, Purnachandra Rao Bhagi

Review of Progress in Quantitative Nondestructive Evaluation

Ultrasonic detection and imaging of flaws in thick coarse grained austenitic stainless steel components is challenging due to very high scattering. Spectral and wavelet transform based methods have been traditionally applied to reduce the noise to detect flaws. We propose a novel ensemble empirical mode decomposition based signal processing method for adaptive detection of flaws in coarse grained austenitic stainless steel.

We have analyzed ultrasonic signals obtained from stainless steel specimens of different grain size (30-200 µm) with and without flaws. The ultrasonic signals lie in two different scattering regimes with wavelength to grain size ratio of 1.8 (near ...


A Novel Approach For Rapid Eddy Current Imaging Of Flaws, Ana Kumar Soni, Purnachandra Rao Bhagi 2016 Indira Gandhi Centre for Atomic Research

A Novel Approach For Rapid Eddy Current Imaging Of Flaws, Ana Kumar Soni, Purnachandra Rao Bhagi

Review of Progress in Quantitative Nondestructive Evaluation

Traditionally raster scan plan is employed in eddy current testing for imaging flaws in components. Several parallel scans using a single probe are made and the acquired data is represented in the form an image to obtain, e.g. a comprehensive picture of a flaw in the imaged region. For imaging on large surfaces time for imaging is a constraint. We present a novel probe scan plan for rapid eddy current imaging of flaws. We demonstrate the performance of this scan plan in austenitic stainless steel plates for detection of flaws using a pancake type eddy current probe. We then ...


Disrupting Long-Range Polar Order With An Electric Field, Hanzheng Guo, Xiaoming Liu, Fei Xue, Long-Qing Chen, Wei Hong, Xiaoli Tan 2016 Iowa State University

Disrupting Long-Range Polar Order With An Electric Field, Hanzheng Guo, Xiaoming Liu, Fei Xue, Long-Qing Chen, Wei Hong, Xiaoli Tan

Materials Science and Engineering Publications

lectric fields are known to favor long-range polar order through the aligning of electric dipoles in relation to Coulomb's force. Therefore, it would be surprising to observe a disordered polar state induced from an ordered state by electric fields. Here we show such an unusual phenomenon in a polycrystalline oxide where electric fields induce a ferroelectric-to-relaxor phase transition. The nonergodic relaxor phase with disordered dipoles appears as an intermediate state under electric fields during polarization reversal of the ferroelectric phase. Using the phenomenological theory, the underlying mechanism for this unexpected behavior can be attributed to the slow kinetics of ...


On The Distance Spectra Of Graphs, Ghodratollah Aalipour, Aida Abiad, Zhanar Berikkyzy, Jay Cummings, Jessica De Silva, Wei Gao, Kristin Heysse, Leslie Hogben, Franklin H.J. Kenter, Jephian C.H. Lin, Michael Tait 2016 Kharazmi University

On The Distance Spectra Of Graphs, Ghodratollah Aalipour, Aida Abiad, Zhanar Berikkyzy, Jay Cummings, Jessica De Silva, Wei Gao, Kristin Heysse, Leslie Hogben, Franklin H.J. Kenter, Jephian C.H. Lin, Michael Tait

Mathematics Publications

The distance matrix of a graph G is the matrix containing the pairwise distances between vertices. The distance eigenvalues of G are the eigenvalues of its distance matrix and they form the distance spectrum of G. We determine the distance spectra of double odd graphs and Doob graphs, completing the determination of distance spectra of distance regular graphs having exactly one positive distance eigenvalue. We characterize strongly regular graphs having more positive than negative distance eigenvalues. We give examples of graphs with few distinct distance eigenvalues but lacking regularity properties. We also determine the determinant and inertia of the distance ...


Full-Field Structural Dynamics By Video Motion Manipulations, Yongchao Yang, Charles Farrara, David Mascarenasa 2016 Los Alamos National Laboratory

Full-Field Structural Dynamics By Video Motion Manipulations, Yongchao Yang, Charles Farrara, David Mascarenasa

Review of Progress in Quantitative Nondestructive Evaluation

Structures with complex geometries, material properties, and boundary conditions, exhibit spatially local, temporally transient, dynamic behaviors. High spatial and temporal resolution vibration measurements and modeling are thus required for high-fidelity characterization, analysis, and prediction of the structure’s dynamic phenomena. For example, high spatial resolution mode shapes are needed for accurate vibration-based damage localization. Also, higher order vibration modes typically contain local structural features that are essential for high-fidelity dynamic modeling of the structure. In addition, while it is possible to build a highly- refined mathematical model (e.g., a finite element model) of the structure, it needs to be ...


Raw Data Based Image Processing Algorithm For Fast Detection Of Surface Breaking Cracks Using In-Line Laser Thermography, Sruthi Krishna, Nithin Puthiyaveettil, P. Biju, Krishnan Balasubramaniam 2016 Indian Institute of Technology Madras

Raw Data Based Image Processing Algorithm For Fast Detection Of Surface Breaking Cracks Using In-Line Laser Thermography, Sruthi Krishna, Nithin Puthiyaveettil, P. Biju, Krishnan Balasubramaniam

Review of Progress in Quantitative Nondestructive Evaluation

The aim of this work is to illustrate the contribution of signal processing techniques in the field of Non-Destructive Evaluation. A component’s life evaluation is inevitably related to the presence of flaws in it. The detection and characterization of cracks prior to damage is a technologically and economically significant task and is of very importance when it comes to safety-relevant measures. The Laser Thermography is the most effective and advanced thermography method for Non-Destructive Evaluation. High capability for the detection of surface cracks and for the characterization of the geometry of artificial surface flaws in metallic samples of laser ...


Full Matrix Capture And The Total Focusing Imaging Algorithm Using Laser Induced Ultrasonic Phased Arrays, Theodosia Stratoudaki, Matt Clark, Paul D. Wilcox 2016 University of Bristol

Full Matrix Capture And The Total Focusing Imaging Algorithm Using Laser Induced Ultrasonic Phased Arrays, Theodosia Stratoudaki, Matt Clark, Paul D. Wilcox

Review of Progress in Quantitative Nondestructive Evaluation

Laser ultrasonics is a technique where lasers are used for the generation and detection of ultrasound instead of conventional piezoelectric transducers. The technique is broadband, non-contact, and couplant free, suitable for large stand-off distances, inspection of components of complex geometries and hazardous environments. In this paper, array imaging is presented by obtaining the full matrix of all possible laser generation, laser detection combinations in the array (Full Matrix Capture), at the nondestructive, thermoelastic regime. An advanced imaging technique developed for conventional ultrasonic transducers, the Total Focusing Method (TFM) [2], is adapted for laser ultrasonics and then applied to the captured ...


Compression Of Multi-Frequency Eddy Current Data Using Principal Components Analysis For Pressure Tube To Calandria Tube Gap Measurement, Shaddy Shokralla, Jordan Morelli, Thomas W. Krause 2016 Queen’s University

Compression Of Multi-Frequency Eddy Current Data Using Principal Components Analysis For Pressure Tube To Calandria Tube Gap Measurement, Shaddy Shokralla, Jordan Morelli, Thomas W. Krause

Review of Progress in Quantitative Nondestructive Evaluation

Inspection of components with multi-variable influential parameters may result in a loss of accuracy for the measurement of the target variable. A particular example occurs in the case of a pressure tube (PT) that is contained within a calandria tube (CT) in the fuel channels of CANDU® nuclear reactors. Eddy current (EC) based measurement of gap between PT and CT, as required by nuclear regulators, is affected by variation of PT wall thickness and resistivity, which may confound the accurate gap measurement. In this work principal components analysis (PCA) is examined as a means of simplifying changes in multi-frequency EC ...


Model Benchmarking And Reference Signals For Angled-Beam Shear Wave Ultrasonic Nde Inspections, John C. Aldrin, Deborah Hopkins, Mark Warchol, Lyudmila V. Warchol, David S. Forsyth, Charlie Buynak, Eric A. Lindgren 2016 Computational Tools, Gurnee

Model Benchmarking And Reference Signals For Angled-Beam Shear Wave Ultrasonic Nde Inspections, John C. Aldrin, Deborah Hopkins, Mark Warchol, Lyudmila V. Warchol, David S. Forsyth, Charlie Buynak, Eric A. Lindgren

Review of Progress in Quantitative Nondestructive Evaluation

NDE modeling and simulation are important tools to support the development and validation of enhanced localization and characterization techniques. Previously, important achievements were made by the USAF to address crack detection in aircraft structures using angled-beam shear wave inspection techniques. However, new work on model benchmarking is needed to move beyond detection and achieve reliable crack characterization. To achieve this goal, simulated studies are needed to verify that models can accurately represent all of the key variables with the inspection of multilayer structures with fastener sites and varying crack conditions. Often with model benchmark studies, the accuracy of the model ...


Existing Weld Seam Recognition And Tracking Based On Sub Region Image Processing, Guoan Liang, Shanshan Wang, Chunlei Tu, Xingsong Wang 2016 Special Equipment Safety Supervision Inspection Institute of Jiangsu Province

Existing Weld Seam Recognition And Tracking Based On Sub Region Image Processing, Guoan Liang, Shanshan Wang, Chunlei Tu, Xingsong Wang

Review of Progress in Quantitative Nondestructive Evaluation

This paper proposes a new algorithm of weld seam recognition for existing weld seam tracking based on sub region neural network. The original images need to be reduced by half and transformed to gray image. Then each picture is divided into 96 small pictures. Sub region neural network of three layers is applied to each small picture. The identification of 96 sub pictures is synthetized to complete the weld seam recognition result of each image. Before training, 5000 samples are obtained in total and they are classified into two categories. 4000 sets of them are considered as training data and ...


Application Of Radon Transform To Wavefield Filtering, Reconstruction, And Imaging Of Dispersive Energies In Quantitative Bone Ultrasound, Lawrence H. Le, Mauricio D. Sacchi 2016 University of Alberta

Application Of Radon Transform To Wavefield Filtering, Reconstruction, And Imaging Of Dispersive Energies In Quantitative Bone Ultrasound, Lawrence H. Le, Mauricio D. Sacchi

Review of Progress in Quantitative Nondestructive Evaluation

Multichannel ultrasonic axial-transmission data are multimodal by nature. Multichannel analysis of dispersive ultrasonic energies requires a reliable mapping of the data from the time– distance (t-x) domain to the frequency–wavenumber (f-k) or frequency–phase velocity (f-c) domain. The mapping is usually performed with the classical 2-D Fourier transform (FT) from t- x plane to f-k plane or to f-c plane with a subsequent substitution and interpolation via c=ω/k. The extracted dispersion trajectories of the guided modes lack the resolution in the transformed domain to discriminate wave modes. The resolving power associated with the FT is closely linked ...


Further Development Of Image Processing Algorithms To Improve Detectability Of Defects In Sonic Ir Nde, Omar Obeidat, Qiuye Yu, Xiaoyan Han 2016 Wayne State University

Further Development Of Image Processing Algorithms To Improve Detectability Of Defects In Sonic Ir Nde, Omar Obeidat, Qiuye Yu, Xiaoyan Han

Review of Progress in Quantitative Nondestructive Evaluation

Sonic Infrared Imaging (SIR) technology is a relatively new NDE technique that has received significant acceptance in the NDE community. SIR NDE is a super-fast, wide range NDE method. The technology uses short pulses of ultrasonic excitation together with infrared imaging to detect defects in the structures under inspection. Defects become visible to the IR camera when the temperature in the crack vicinity increases due to various heating mechanisms in the specimen. Defect detection is highly affected by noise levels as well as mode patterns in the image. Mode patterns result from the superposition of sonic waves interfering within the ...


Nonlinear Mixing Algorithm For Rivet Signal Suppression In Ec-Gmr Inspection Of Multilayer Structures, Seyed Safdernejad, Oleksii Karpenko, Chaofeng Ye, Lalita Udpa, Satish Udpa 2016 Michigan State University

Nonlinear Mixing Algorithm For Rivet Signal Suppression In Ec-Gmr Inspection Of Multilayer Structures, Seyed Safdernejad, Oleksii Karpenko, Chaofeng Ye, Lalita Udpa, Satish Udpa

Review of Progress in Quantitative Nondestructive Evaluation

Giant Magneto-Resistive (GMR) sensors have recently emerged as a promising tool for Eddy Current (EC) inspection of multi-layer riveted structures. However, the detection of defects under fasteners remains a challenging problem, since the distortion of the induced magnetic field introduced by subsurface flaws is masked by the strong responses from steel fasteners and structural edges. Multi-frequency EC-GMR measurements can be used to suppress the rivet signal, while retaining defect indications and hence increase the detectability of defects. In this paper, we propose a novel generic filter for processing EC-GMR measurements acquired at a single or multiple excitation frequencies to suppress ...


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