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ULTRASONIC VOID ESTIMATION SYSTEM FOR DETERMINATION OF LIQUIDS IN MICROGRAVITY TANKS

IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT 1988年第4期37卷 642-647页

作者： ROBERTI, D LOOFT, FJ LUDWIG, R Department of Electrical Engineering Worcester Polytechnic Institute Worcester MA USA

An ultrasonic measurement technique has been developed for determining the quantity of liquid storage tanks in the microgravity environment. When the void fraction in a vessel is sufficiently small and the liquid wets the vessel, a spherical void interior to the liquid forms. The proposed procedure, the void estimate center technique (VECT), uses an iterative algorithm to compute the center location and thus the radius of a spherically shaped void. The VECT algorithm has been developed as a two-dimensional model that can also be easily extended to three-dimensional problems. After evaluating different transducer locations, a prototype was constructed and its performance was evaluated. Both system design and hardware are discussed in detail.< >

关键词： Liquids Volume measurement Ultrasonic variables measurement Ultrasonic imaging Measurement techniques Extraterrestrial measurements Iterative algorithms Gravity Transducers Prototypes

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A HIGH-PERFORMANCE PIPELINED ARCHITECTURE FOR MEASUREMENT AND MONITORING OF MULTIPLE SENSOR SIGNALS

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IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT 1992年第6期41卷 808-814页

作者： ROTITHOR, HG Department of Electrical Engineering Worcester Polytechnic Institute Worcester MA USA

In this paper, a high-performance pipelined architecture with hardware sharing for measurement and monitoring of signals generated by sensors that measure physical quantities is presented. Pipelining provides the necessary computational power and has potential for minimizing the input sampling to output monitoring delay, while hardware sharing results in a lower cost. The three segments in the pipeline are: sample acquisition, sample processing, and output monitoring. Each segment is implemented using one or more microprocessors. Various considerations involved in the design of a pipelined architecture are discussed, and a simple model to predict the computing power required and the maximum delay incurred for an application is presented.

关键词： Pipeline processing ARCHITECTURE Building construction pipeline sample processing Sensors signals computer hardware computational power HIGH-PERFORMANCE

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A NONDESTRUCTIVE ULTRASONIC-IMAGING SYSTEM FOR DETECTION OF FLAWS IN METAL BLOCKS

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IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT 1989年第1期38卷 113-118页

作者： LUDWIG, R ROBERTI, D Department of Electrical Engineering Worcester Polytechnic Institute Worcester MA USA

An ultrasonic imaging system is presented for the nondestructive evaluation of internal defects in metal blocks. The surfaces of the blocks are coarsely scanned by a single ultrasonic transducer to record multiple A-scans. The recorded A-scans are processed by a synthetic-aperture focusing technique (SAFT) algorithm to search for defects in a metal specimen. The processed information is then sent to a graphics package to be displayed on a CRT screen of a personal computer. The current linear imaging technique is presented and is compared to the SAFT algorithm. The theory and limitations of the SAFT algorithm as well as the hardware implementation are discussed. Images of defects in aluminum blocks are illustrated with varying operating parameters showing the performance of the imaging system.< >

关键词： Ultrasonic imaging Acoustic transducers Acoustic reflection Impedance Hardware Aluminum Nondestructive testing Safety X-rays Ultrasonic transducers

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NONLINEAR QUANTIZATION AND THE DESIGN OF CODED AND UNCODED SIGNAL CONSTELLATIONS

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IEEE TRANSACTIONS ON COMMUNICATIONS 1991年第8期39卷 1207-1215页

作者： PAHLAVAN, K Department of Electrical Engineering Worcester Polytechnic Institute Worcester MA USA

This paper analyzes the effects of nonlinear quantizers, used in T1 carrier systems, on the performance of QAM and trellis code modulated (TCM) voice-band data communication modems, and introduces a method to counteract the effects of these nonlinearities. The effects of nonlinear quantizers used in the T1 carrier systems is modeled as a source of multiplicative noise whose variance is proportional to the amplitude of the quantized signal. The relation between variance of the multiplicative noise, characteristics of the nonlinear quantizer, and impulse response of the pulse shaping filters used in the modems are derived. Effects of multiplicative noise on the performance of QAM and TCM modems are analyzed. A method for the design of QAM and TCM signal constellations is introduced which counteracts the harmful effects of nonlinear quantizers. It is shown that the new constellations provide 2-3 dB performance improvements in multiplicative noise channels at the expense of losing less than 0.5 dB in additive noise channels.

关键词： .additive noise nonlinearities data communication modems Signal Constellations counteract carrier systems nonlinear quantizers QAM and TCM multiplicative noise channels

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A HYBRID FINITE-ELEMENT METHOD OF MOMENT FORMULATION FOR SINGLE FREQUENCY EDDY-CURRENT INVERSION

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IEEE TRANSACTIONS ON MAGNETICS 1992年第3期28卷 1843-1849页

作者： WISMER, MG LUDWIG, R Department of Electrical Engineering Worcester Polytechnic Institute Worcester MA USA

Eddy-current inverse techniques using single frequency currents have been applied with limited success to the reconstruction of crack width and thickness profiles primarily for one-dimensional and axisymmetric geometries. Because of the diffusive nature of the induced low frequency eddy currents the reconstruction process differs from high frequency wave propagation methods. On the physical basis that both diffusive and wave phenomena can be described by the same Green's function with either a complex or real wave number, an integral formulation for the low frequency magnetic vector potential is presented. By employing an iterative Born approximation algorithm and the method of moments, a reconstruction method for the conductivity profile in a metallic specimen is developed. To make this formulation amenable to complex geometries, finite element analysis techniques are utilized to compute the integral kernel. The inversion process is tested with synthetic data generated by the numerical solution of a generic embedded flaw in a full-space and a surface-breaking defect.

关键词： Finite element methods Moment methods Geometry Eddy currents Green's function methods Iterative methods Scattering Approximation methods Approximation algorithms Iterative algorithms

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NOVEL 4TH-ORDER SIGMA-DELTA CONVERTER

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ELECTRONICS LETTERS 1992年第15期28卷 1437-1438页

作者： BAHER, H AFIFI, E Electrical Engineering Department Worcester Polytechnic Institute Worcester USA

A new fourth-order sigma-delta A/D convertor is proposed as a cascade of two second-order sections. Its advantages over the alternative cascade of four first-order sections are presented. It is also shown that the proposed design gives certain improvements in performance over a third order cascade of a second and first-order section, thus justifying the use of a higher order.

关键词： ANALOG DIGITAL CONVERSION CIRCUIT DESIGN

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DESIGN AND ANALYSIS OF 2-CHANNEL HIGH DEFINITION TELEVISION SYSTEMS

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IEEE TRANSACTIONS ON BROADCASTING 1990年第2期36卷 175-183页

作者： NASRABADI, NM CHOO, CY Department of Electrical Engineering Worcester Polytechnic Institute Worcester MA USA

A technique for the analysis of two-channel high-definition television (HDTV) transmission systems is presented. Design methods based on limitations due to the combined spatial and temporal characteristics of the human visual system (HVS) are developed. The concepts of resolution imbalance, recognizability, and spatial-temporal multiplexing are explained. The design and analysis of two-channel NTSC-compatible HDTV systems having an aspect ratio of 16:9 with double the vertical and horizontal resolution of the present NTSC system is described. It is shown that such a system requires more than two channels for transmission. Signal processing techniques are suggested to improve the quality of the images without using any extra channels. Time multiplexing of different frequency bands are used to exploit the psychovisual redundancies of the HVS to reduce the number of pels to be transmitted. Finally, comparing the spatial resolutions of the reconstructed images by a two-channel HDTV system with that of the HVS, it is found that the spatial resolution are not yet as good as that of the HVS.

关键词： Spatial resolution HDTV system time characteristic Human Characteristics Frequency bands National Television Systems Committee Image quality horizontal resolution ASPECT RATIO 2-channel

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NUMERICAL AND ANALYTICAL MODELING OF PULSED EDDY CURRENTS IN A CONDUCTING HALF-SPACE

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IEEE TRANSACTIONS ON MAGNETICS 1990年第1期26卷 299-307页

作者： LUDWIG, R DAI, XW Department of Electrical Engineering Worcester Polytechnic Institute Worcester MA USA

A weighted-residual-based finite-element model for the computation of transient two-dimensional and axisymmetric magnetic vector potential and eddy-current distributions is formulated. The numerical field predictions are quantitatively tested against two analytical models in the time domain employing inverse Laplace transforms. The basis for the comparison is the determination of the eddy-current distribution in a conducting, nonmagnetic half-space due to either a suspended infinite wire or a suspended current loop. Although the excitation source for both methods is unit step current, the extension to arbitrary transient excitation currents and their corresponding eddy-current responses can be carried out by means of convolution. The resulting numerical temporal and spatial eddy-current distributions at various depths in the half-space are in excellent agreement with analytical distributions, thus quantitatively validating the numerical approach as a viable technique applicable to realistic nondestructive testing situations where field interactions with often arbitrary flaw geometries are of concern.< >

关键词： Analytical models Numerical models Eddy currents Magnetic analysis Finite element methods Computational modeling Distributed computing Magnetic domains Testing Time domain analysis

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A Hybrid Deep Learning Framework for IoT Security Enhancement and Anomaly Detection

A Hybrid Deep Learning Framework for IoT Security Enhancemen...

引用

Integrated Circuits and Communication Systems (ICICACS), IEEE International Conference on

作者： D Baswaraj Abdur Rahman Deependra Pandey T Bhargavi Muslimbek Ismoilov Natha Deepthi Department of Computer Science and Engineering Vasavi College of Engineering Hyderabad India School of Business & Technology Emporia State University Emporia Kansas USA Department of Electronics and Communication Engineering Amity School of Engineering & Technology (ASET) Amity University Lucknow India Department of Information Technology St. Martins Engineering College Hyderabad India Department of Electrical Engineering Fergana Polytechnic Institute Fergana Uzbekistan Department of Computer Science and Engineering Koneru Lakshmaiah Education Foundation Guntur India

ISBN: (数字)9798331508456

ISBN: (纸本)9798331508463

Cyber threats targeting Internet-of-Things(IoT) devices have grown in frequency and severity alongside the IoT's fast uptake and usage in the past few years. Because of this, creating a model that can detect hostile attacks and lessen security risks in IoT-devices is becoming a very important subject. Botnets pose a significant risk because they disrupt the networks that Internet of Things (IoT) devices rely on to function. An method called GA-HDLAD, which stands for genetic-algorithm with hybrid deep learning(DL), was created in this study to advance security in the IoT environment by detecting botnets. Botnet detection makes use of hybrid deep learning, which combines attention concepts, feature-extraction-techniques(FETs), and recurrent-neural-networks(RNNs). The hybrid-DL approach can identify botnet attacks, which frequently use complicated patterns. In addition, the model's RNNs capture temporal dependencies, while FETs guarantee efficient feature extraction from geographical data. To choose the hyperparameters required by the HDL method, simulated annealing (SA) is employed. This paper compares the GA-HDLAD system to other detection approaches and finds that it outperforms them experimentally using a benchmark botnet dataset.

关键词： Deep learning Integrated circuits Botnet Field effect transistors Simulated annealing Feature extraction Internet of Things Security Hardware design languages Anomaly detection

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INTERDOME INTERACTIONS IN CUTANEOUS TYPE-I RECEPTORS

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IEEE TRANSACTIONS ON BIOMEDICAL engineering 1988年第11期35卷 973-980页

作者： LOOFT, FJ Department of Electrical Engineering Worcester Polytechnic Institute Worcester MA USA

The encoder characteristics of cat, hairy skin, slowly adapting Type I receptors were studied by activating them with 'swept period' grating stimuli. A typical stimulus featured a minimum scan period of 0.3 mm, a maximum scan period of 2.0 mm, and a total of 40 grates. Using these stimuli, single domes could easily encode the temporal frequency (1/period*scan velocity) of a grate, regardless of the scan velocity or direction. Receptors with multiple domes could not encode the temporal frequency of a swept-period stimulus unless the instantaneous grate period matched a receptor's intrinsic ability to encode the stimulus. When this criterion was met, the temporal frequency of the stimulus was encoded in the bursting rate of the receptor's action potential event stream.< >

关键词： Frequency Skin Gratings

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