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Articles 32041 - 32070 of 36822

Full-Text Articles in Engineering

An Algebraic Algorithm For Nonuniformity Correction In Focal-Plane Arrays, Bradley M. Ratliff, Majeed M. Hayat, Russell C. Hardie Jan 2002

An Algebraic Algorithm For Nonuniformity Correction In Focal-Plane Arrays, Bradley M. Ratliff, Majeed M. Hayat, Russell C. Hardie

Electrical and Computer Engineering Faculty Research and Publications

A scene-based algorithm is developed to compensate for bias nonuniformity in focal-plane arrays. Nonuniformity can be extremely problematic, especially for mid- to far-infrared imaging systems. The technique is based on use of estimates of interframe subpixel shifts in an image sequence, in conjunction with a linear-interpolation model for the motion, to extract information on the bias nonuniformity algebraically. The performance of the proposed algorithm is analyzed by using real infrared and simulated data. One advantage of this technique is its simplicity; it requires relatively few frames to generate an effective correction matrix, thereby permitting the execution of frequent on-the-fly nonuniformity …

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Model Predictive Control Of Cstr Based On Local Model Networks, Ruiyao Gao, Aidan O'Dwyer, Eugene Dermot Coyle Professor Jan 2002

Model Predictive Control Of Cstr Based On Local Model Networks, Ruiyao Gao, Aidan O'Dwyer, Eugene Dermot Coyle Professor

Conference papers

A non-linear predictive controller is presented. It judiciously combines predictive controllers with a local model network utilizing a neural-network-like gating system. It avoids the time consuming quadratic optimization calculation, which is normally necessary in non-linear predictive control. A controller simulation on a Continuous Stirred Tank Reactor (CSTR) case study was shown to be satisfactory both in terms of set point tracking and regulation performance over the entire operating range. Moreover, the inherent integration action in the local predictive controller provides zero static offsets.

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Closed Loop Identification Of A First Order Plus Dead-Time Process Model Under Pi Control, Tony Kealy, Aidan O'Dwyer Jan 2002

Closed Loop Identification Of A First Order Plus Dead-Time Process Model Under Pi Control, Tony Kealy, Aidan O'Dwyer

Conference papers

This paper discusses the estimation of the parameters of a first order plus dead-time process model using the closed-loop step response data of the process under proportional plus integral (PI) control. The proportional gain and the integral time, in the PI controller, are chosen such that the closed-loop step response exhibits an under-damped response. From this response data, five characteristic points are used to determine a second order plus dead-time model and subsequently, the frequency response of the closed-loop system. Knowing the dynamics of the closed-loop system and the dynamics of the controller, the open-loop dynamics of the process can …

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Comparison Of Open And Closed Loop Process Identification Techniques In The Time Domain, Tony Kealy, Aidan O'Dwyer Jan 2002

Comparison Of Open And Closed Loop Process Identification Techniques In The Time Domain, Tony Kealy, Aidan O'Dwyer

Conference papers

This paper describes seven methods to identify a mathematical model for a real process with a time delay. The process is the Process Trainer, PT326 from Feedback Instruments Limited. Six of the methods use the step response data and one of the methods uses the impulse response data for identification.

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The Changing Roles Of Analog And Digital Signal Processing In Cmos Image Sensors, John G. Harris Jan 2002

The Changing Roles Of Analog And Digital Signal Processing In Cmos Image Sensors, John G. Harris

Electrical and Computer Engineering Faculty Research & Creative Works

Throughout the years digital signal processing has been encroaching more and more into what had previously been exclusive analog circuit domains. Here we briefly summarize various lines of research in CMOS imaging sensoring technology paying special attention to the gradual transition from analog to digital processing. The transition from continuous-time continuous-value pixels to digital (discrete-time binary-value) pixels could be viewed as the natural final step in the evolution of these imaging circuits in order to achieve wide dynamic range with acceptable signal to noise ratio. After data is read off a digital pixel imager chip, digital signal processing is required …

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Increased Mfcc Filter Bandwidth For Noise-Robust Phoneme Recognition, Mark D. Skowronski, John G. Harris Jan 2002

Increased Mfcc Filter Bandwidth For Noise-Robust Phoneme Recognition, Mark D. Skowronski, John G. Harris

Electrical and Computer Engineering Faculty Research & Creative Works

Many speech recognition systems use mel-frequency cepstral coefficient (MFCC) feature extraction as a front end. In the algorithm, a speech spectrum passes through a filter bank of mel-spaced triangular filters, and the filter output energies are log-compressed and transformed to the cepstral domain by the DCT. The spacing of filter bank center frequencies mimics the known warped-frequency characteristics of the human auditory system, yet the bandwidths of these filters are not chosen through biological inspiration. Instead, they are set by aligning endpoints of the triangle, which is itself an arbitrary shape. It is surprising that for such a popular speech …

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End To End Congestion Control In High-Speed Networks, Sarangapani Jagannathan Jan 2002

End To End Congestion Control In High-Speed Networks, Sarangapani Jagannathan

Electrical and Computer Engineering Faculty Research & Creative Works

This paper proposes an adaptive methodology to prevent congestion in packet switched networks such as the Internet, where the internal network nodes convey very little information to the ingress nodes. Two architectures of preventing the congestion are presented: the first one when the traffic arrival rates, and bottleneck queue levels are known and the other when these are unknown. In the latter, the network traffic is estimated online using an adaptive system by measuring the buffer occupancy. In both architectures, the congestion is controlled by adjusting the transmission rates of non real-time and certain real-time sources in response to the …

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Distributed Power Control In Wireless Communication Systems, Sarangapani Jagannathan, A. T. Chronopoulos, S. Ponipireddy Jan 2002

Distributed Power Control In Wireless Communication Systems, Sarangapani Jagannathan, A. T. Chronopoulos, S. Ponipireddy

Electrical and Computer Engineering Faculty Research & Creative Works

Energy efficiency is a measure of performance in wireless networks. Therefore, controlling the transmitter power at a given node increases not only battery operating life, but also overall system capacity by successfully admitting new links. It is essential to find effective means of power control in point-to-point, broadcasting and multicasting scenarios. Wireless networking presents formidable challenges, and we consider the problem of unicast or point-to-point (peer-to-peer) communication in wireless networks in the presence of other nodes. We study the feasibility of admitting new links in an wireless network operating area while maintaining quality of service (QoS), in terms of signal-to-interference …

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A Hybrid System Theoretic Approach For Admission Controller Design In Multimedia Networks, Sarangapani Jagannathan Jan 2002

A Hybrid System Theoretic Approach For Admission Controller Design In Multimedia Networks, Sarangapani Jagannathan

Electrical and Computer Engineering Faculty Research & Creative Works

A novel real-time discrete-event admission control (AC) scheme for high-speed networks is proposed with the aim of attaining a desired quality of service (QoS) and high network utilization. The AC uses the available capacity from a novel adaptive bandwidth estimation scheme, a congestion indicator derived from a congestion controller, peak bit/cell rate (PBR/PCR) estimate from new sources, along with the desired QoS metrics, and makes decisions whether to 'admit' or 'reject' new sources. The novel aspect of the proposed approach is the application of hybrid system theory to prove the performance of the admission controller, stability and the development of …

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Study Of Relative Effectiveness Of Features In Content-Based Image Retrieval, S. R. Subramanya, Jui Che Teng, Yongjian Fu Jan 2002

Study Of Relative Effectiveness Of Features In Content-Based Image Retrieval, S. R. Subramanya, Jui Che Teng, Yongjian Fu

Electrical and Computer Engineering Faculty Research & Creative Works

Content-based retrieval in image databases requires appropriate features of images to be derived and used in the indexing and searching process. Fast and accurate retrieval is crucial from a user point of view. The kinds of features used, their organization in suitable data structures, and the similarity search scheme, directly affect the speed and quality of content-based retrieval. In this paper, we evaluate the relative significance of three different image features - geometry, moments, and Fourier descriptors in the context of content-based retrieval, and present experimental results. The evaluation metrics are retrieval quality and search time. These could be used …

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Incorporation Of Cerium And Neodymium In A Uranyl Hydroxide Solid, Chang-Soo Kim, David J. Wronkiewicz, R. J. Finch, E. C. Buck Jan 2002

Incorporation Of Cerium And Neodymium In A Uranyl Hydroxide Solid, Chang-Soo Kim, David J. Wronkiewicz, R. J. Finch, E. C. Buck

Electrical and Computer Engineering Faculty Research & Creative Works

The migration behavior of radionuclides in a nuclear-waste repository will be influenced, in part, by their equilibrium solubilities in the presence of radionuclide-bearing solids and/or adsorption affinities as trace components onto the surfaces of solid host phases. Uranium phases that precipitate on the surface of altered spent nuclear fuel may thus influence the mobility of radionuclides released in the near-field environment, since by proximity, these will be the first phases that the radionuclides encounter following their release from the spent fuel matrix. We have evaluated the potential for incorporating radionuclides into crystalline compounds by precipitating uranyl phases from aqueous solutions …

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Development Of A Testbed For Design And Evaluation Of Power Electronic Based Systems, S. Pekarek, J. Tichenor, N. Benavides, A. Koenig, H. Wang, Scott D. Sudhoff, B. Kuhn, S. Glover, D. Aliprantis, J. Byoun, J. Sauer Jan 2002

Development Of A Testbed For Design And Evaluation Of Power Electronic Based Systems, S. Pekarek, J. Tichenor, N. Benavides, A. Koenig, H. Wang, Scott D. Sudhoff, B. Kuhn, S. Glover, D. Aliprantis, J. Byoun, J. Sauer

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, a detailed technical description of a new hardware-based integrated power system testbed is presented. The testbed consists of an AC generation and propulsion system that is coupled to a DC zonal distribution system. A primary objective of the testbed is to provide a resource to the academic and industrial community by providing a non-proprietary system on which to demonstrate controls, survivability algorithms, and validate computer-aided design (CAD) tools. Copyright © 2002 Society of Automotive Engineers, Inc.

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Comparison Of Mlp And Rbf Neural Networks Using Deviation Signals For On-Line Identification Of A Synchronous Generator, Jung-Wook Park, Ganesh K. Venayagamoorthy, Ronald G. Harley Jan 2002

Comparison Of Mlp And Rbf Neural Networks Using Deviation Signals For On-Line Identification Of A Synchronous Generator, Jung-Wook Park, Ganesh K. Venayagamoorthy, Ronald G. Harley

Electrical and Computer Engineering Faculty Research & Creative Works

This paper compares the performances of a multilayer perceptron network (MLPN) and a radial basis function network (RBFN) for the online identification of the nonlinear dynamics of a synchronous generator. Deviations of signals from their steady state values are used. The computational complexity required to process the data for online training, generalization and online global minimum testing are investigated by time-domain simulations. The simulation results show that, compared to the MLPN, the RBFN is simpler to implement, needs less computational memory, converges faster and global minimum convergence is achieved even when operating conditions change.

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Second-Order Statistical Properties Of The Wss Jakes' Fading Channel Simulator, Chengshan Xiao, Y. Rosa Zheng, N. C. Beaulieu Jan 2002

Second-Order Statistical Properties Of The Wss Jakes' Fading Channel Simulator, Chengshan Xiao, Y. Rosa Zheng, N. C. Beaulieu

Electrical and Computer Engineering Faculty Research & Creative Works

An improved Jakes' (1994) fading channel simulator was proposed by Pop and Beaulieu (see ibid., vol.49, p.699-708, Apr. 2001) to eliminate the stationarity problem occurring in Jakes' original design. In this paper, second-order statistical properties of the improved Jakes' simulator are analyzed. Consistent with Pop and Beaulieu's caution about high-order statistics of the simulator, it is proved that some second-order statistics of both the quadrature components and the envelope do not match the desired ones even if the number of sinusoids approaches infinity. Therefore, care must be taken when the simulator is employed to evaluate algorithms and systems.

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Software Engineering As A Business, Ann K. Miller, C. Ebert Jan 2002

Software Engineering As A Business, Ann K. Miller, C. Ebert

Electrical and Computer Engineering Faculty Research & Creative Works

No abstract provided.

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Tissue Classification Through Analysis Of Gene Expression Data Using A New Family Of Art Architectures, Rui Xu, Georgios C. Anagnostopoulos, Donald C. Wunsch Jan 2002

Tissue Classification Through Analysis Of Gene Expression Data Using A New Family Of Art Architectures, Rui Xu, Georgios C. Anagnostopoulos, Donald C. Wunsch

Electrical and Computer Engineering Faculty Research & Creative Works

Correct classification is crucial to cancer diagnosis and treatment. We demonstrate that a new family of neural network architectures-Ellipsoid ART and ARTMAP (EA/EAM)-can cluster and classify tissues successfully through analysis of gene expression data generated by DNA microarray experiments

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A Cascaded Converter-Based Statcom With Energy Storage, Chang Qian, Mariesa Crow Jan 2002

A Cascaded Converter-Based Statcom With Energy Storage, Chang Qian, Mariesa Crow

Electrical and Computer Engineering Faculty Research & Creative Works

Due to their advantages in high power applications, multi-level converters have been introduced to flexible AC Transmission Systems (FACTS) to enhance power transmission system operation. Although several multi-level StatCom topologies have been proposed to verify the high performance of multi-level converters used in reactive power compensation, they are not capable of controlling active power flow. To make multi-level converters more flexible and effective for active power flow control, energy storage systems, such as flywheels and batteries are incorporated into StatComs. In this paper, battery energy storage systems (BESS) are incorporated into a cascaded converter-based StatCom to implement both active and …

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A Diode-Clamped Multi-Level Inverter For The Statcom/Bess, Cheng Ying, Mariesa Crow Jan 2002

A Diode-Clamped Multi-Level Inverter For The Statcom/Bess, Cheng Ying, Mariesa Crow

Electrical and Computer Engineering Faculty Research & Creative Works

Flexible AC transmission systems (FACTS) are potentially becoming more flexible and more economical local controllers in the power system. The integration of traditional FACTS devices with energy storage system (ESS) will increase FACTS device functionality. The voltage-sourced inverter is an important part of many FACTS devices, such as the StatCom and SSSC. Considerable research has been done on 2-level inverter usage in FACTS. Multilevel inverters, however, can improve the voltage quality and reduce the voltage stress on the power electronic devices. This paper uses a diode-clamped multilevel inverter in the StatCom/BESS. The multilevel inverter switching strategy and output voltage model …

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Node Splitting Algorithms In Tree-Structured High-Dimensional Indexes For Similarity Search, Yongjian Fu, Jui Che Teng, S. R. Subramanya Jan 2002

Node Splitting Algorithms In Tree-Structured High-Dimensional Indexes For Similarity Search, Yongjian Fu, Jui Che Teng, S. R. Subramanya

Computer Science Faculty Research & Creative Works

Content-based searches and retrievals in multimedia and image databases use high-dimensional indexing structures for organizing the features of the objects. Most of those index structures are tree-structured whose nodes have a limit on the number of entries describing the subtrees rooted at those nodes. When index trees are built by repeated insertion of entries, nodes need to be split and the tree balanced accordingly. Node-splitting algorithms eventually determine the final structure of the tree which will have a profound effect on the search performance. This paper presents a comparative study of several node splitting algorithms for a typical high-dimensional indexing …

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Sub-Band Independent Subspace Analysis For Drum Transcription, Derry Fitzgerald, Robert Lawlor, Eugene Coyle Jan 2002

Sub-Band Independent Subspace Analysis For Drum Transcription, Derry Fitzgerald, Robert Lawlor, Eugene Coyle

Conference papers

While Independent Subspace Analysis provides a means of separating sound sources from a single channel signal, making it an effective tool for drum transcription, it does have a number of problems. Not least of these is that the amount of information required to allow separation of sound sources varies from signal to signal. To overcome this indeterminacy and improve the robustness of transcription an extension of Independent Subspace Analysis to include sub-band processing is proposed. The use of this approach is demonstrated by its application in a simple drum transcription algorithm.

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Interdisciplinary Graduate Experience: Lessons Learned, Steve Eugene Watkins, V. M. Eller, Josh Corra, M. J. Molander, Bethany Konz, Richard H. Hall, K. Chandrashekhara, Abdeldjelil Belarbi Jan 2002

Interdisciplinary Graduate Experience: Lessons Learned, Steve Eugene Watkins, V. M. Eller, Josh Corra, M. J. Molander, Bethany Konz, Richard H. Hall, K. Chandrashekhara, Abdeldjelil Belarbi

Electrical and Computer Engineering Faculty Research & Creative Works

Engineers interact in the workplace with technical peers in other disciplines at all stages of design, development, and application. Awareness of the constraints and needs of the other disciplines can be key in many situations. Such interdisciplinary activity and the associated communication are facilitated if the all participants have a solid knowledge of discipline-specific terminology and an understanding of connecting concepts. Consequently, experience relating to interdisciplinary teamwork is a necessary component of engineering education. The Smart Engineering Group at the University of Missouri-Rolla was established to conduct interdisciplinary research and to create interdisciplinary educational resources. The topical interest area is …

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A Distributed Discrete-Time Neural Network Architecture For Pattern Allocation And Control, A.T. Chronopoulos, Jagannathan Sarangapani Jan 2002

A Distributed Discrete-Time Neural Network Architecture For Pattern Allocation And Control, A.T. Chronopoulos, Jagannathan Sarangapani

Computer Science Faculty Research & Creative Works

No abstract provided.

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Experimental Verification Of Derivatives Adaptive Critic Based Neurocontroller Performance On Single Turbogenerators On The Electric Power Grid, Ganesh K. Venayagamoorthy, Donald C. Wunsch, Ronald G. Harley Jan 2002

Experimental Verification Of Derivatives Adaptive Critic Based Neurocontroller Performance On Single Turbogenerators On The Electric Power Grid, Ganesh K. Venayagamoorthy, Donald C. Wunsch, Ronald G. Harley

Electrical and Computer Engineering Faculty Research & Creative Works

The design and real-time implementation of derivatives adaptive critic based neurocontrollers that replace the conventional automatic voltage regulators (AVRs) and turbine governors are presented in this paper. The feedback variables to the neurocontroller are completely based on local measurements from the turbogenerator. Experimental verification results are presented to show the superior performance of the derivatives adaptive critic based neurocontroller, compared to the conventional AVR and turbine governor controllers equipped with a power system stabilizer.

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Finite-Element Modeling Of Coaxial Cable Feeds And Vias In Power-Bus Structures, Hao Wang, Yun Ji, Todd H. Hubing Jan 2002

Finite-Element Modeling Of Coaxial Cable Feeds And Vias In Power-Bus Structures, Hao Wang, Yun Ji, Todd H. Hubing

Electrical and Computer Engineering Faculty Research & Creative Works

This paper presents three different models that can be used to represent coaxial cable feeds or vias in printed circuit board power-bus structures. The probe model represents a coaxial feed or via as a current filament with unknown radius. The coaxial-cable model enforces an analytical field distribution at the cable opening or via clearance hole. The strip model employs the equivalent radius concept to represent cylindrical feeds and vias as rectangular strips. Although the strip model is functionally equivalent to two closely positioned probe models, it accurately represents the conductor radius and is more accurate in situations where the via …

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Full Binary Combination Schema For Floating Voltage Source Multi-Level Inverters, X. Kou, Keith Corzine, Yakov L. Familiant Jan 2002

Full Binary Combination Schema For Floating Voltage Source Multi-Level Inverters, X. Kou, Keith Corzine, Yakov L. Familiant

Electrical and Computer Engineering Faculty Research & Creative Works

This paper presents schema of operation for floating voltage source multi-level inverters. The primary advantage of the proposed schema is that the number of voltage levels (and thus power quality) can be increased for a given number of semiconductor devices when compared to the conventional "flying capacitor" topology. However, the new schema requires fixed floating sources instead of capacitors and therefore is more suitable for battery power applications such as electric vehicles, flexible AC transmission systems and submarine propulsion. Alternatively transformer/rectifier circuits may be used to supply the floating sources in a similar way to cascaded H-bridge inverters. Computer simulation …

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Gunn Oscillators Based On Shielded Dielectric Resonators With Mechanical Frequency Tuning, Sergey Kharkovsky, V. I. Lutsenko, I. V. Lutsenko, V. K. Korneenkov, A. E. Kogut Jan 2002

Gunn Oscillators Based On Shielded Dielectric Resonators With Mechanical Frequency Tuning, Sergey Kharkovsky, V. I. Lutsenko, I. V. Lutsenko, V. K. Korneenkov, A. E. Kogut

Electrical and Computer Engineering Faculty Research & Creative Works

The features of Gunn oscillators based on shielded dielectric resonators with whispering gallery modes and ray oscillations are investigated. Their comparative analysis for oscillators with different dielectric resonant structures is carried out.

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High Q Shielded Dielectric Resonator -- The Basis Of Stable Mm-Waves Generator, V. V. Kutuzov, Sergey Kharkovsky, V. A. Solodovnik, K. A. Kutuzov Jan 2002

High Q Shielded Dielectric Resonator -- The Basis Of Stable Mm-Waves Generator, V. V. Kutuzov, Sergey Kharkovsky, V. A. Solodovnik, K. A. Kutuzov

Electrical and Computer Engineering Faculty Research & Creative Works

High Q-factor whispering gallery modes which are excited in a shielded hemispherical dielectric resonator by an external signal or Gunn diode are investigated. Their application as modes of an oscillator with high frequency stability is proposed. The power of the output signal and frequency tuning of an oscillator based on the investigated resonator are measured.

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Improvement Of Power Quality In Vsi Drives, Badrul H. Chowdhury, Ravi Bantu Jan 2002

Improvement Of Power Quality In Vsi Drives, Badrul H. Chowdhury, Ravi Bantu

Electrical and Computer Engineering Faculty Research & Creative Works

The popular VSI (voltage source inverter) drives in use today are mostly PWM (pulse width modulated) drives. Harmonics produced by these drives cause heat losses, reduce the efficiency of the machine and also cause vibrations in the rotor. Active and passive filters are some of the methods to reduce the harmonics generated by these drives. A novel method is discussed which not only eliminates the 5/sup th/ harmonic but also any other negative sequence harmonics. This method, based on a reactor circuit, shows a reduction in harmonics and an improvement in the efficiency of the machine. The method can also …

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Measurement And Monitoring Of Microwave Reflection And Transmission Properties Of Cement-Based Specimens, Sergey Kharkovsky, M. F. Akay, U. C. Hasar, C. D. Atis Jan 2002

Measurement And Monitoring Of Microwave Reflection And Transmission Properties Of Cement-Based Specimens, Sergey Kharkovsky, M. F. Akay, U. C. Hasar, C. D. Atis

Electrical and Computer Engineering Faculty Research & Creative Works

The results of measurement and monitoring of reflection and transmission properties of cement-based specimens (blocks of mortar, concrete) obtained by using a simple and an inexpensive measurement system at microwave frequencies (X-band) are presented. Dependencies of the reflection and transmission coefficients on water-to-cement (w/c) ratio, preparing and curing conditions of the specimens are demonstrated. It is shown that the amplitudes of reflection and transmission coefficients, together with thickness of the specimens, determine the complex dielectric permittivity of the hardened cement-based specimens. The expected applications of the results for the determination of physical properties of cement-based materials are discussed. The causes …

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Multilevel Voltage-Source Duty-Cycle Modulation: Analysis And Implementation, Keith Corzine, J. R. Baker Jan 2002

Multilevel Voltage-Source Duty-Cycle Modulation: Analysis And Implementation, Keith Corzine, J. R. Baker

Electrical and Computer Engineering Faculty Research & Creative Works

Multilevel converters have become increasingly popular due to high power quality, high-voltage capability, low switching losses, and low electromagnetic compatibility concerns. Considering these advantages, the multilevel converter is a suitable candidate for implementation of future naval ship propulsion systems. This paper focuses on modulation techniques for the multilevel converter. In particular, a novel voltage-source method of multilevel modulation is introduced and compared to existing methods. The proposed method is discrete in nature and can therefore be readily implemented on a digital signal processor. The method is also readily extendable to any number of voltage levels. Results of experimental implementation are …

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