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2009

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Articles 2851 - 2880 of 4158

Full-Text Articles in Engineering

Modeling And Characterization Of Rf Mems Resonators, Najla S. Khan Jan 2009

Modeling And Characterization Of Rf Mems Resonators, Najla S. Khan

Electrical Engineering Theses - Archive

Over the past decade, a multitude of micro-electro-mechanical (MEMS) devices have been developed and commercialized due to their low power consumption, reduced cost and compact size. In recent years, significant advancements in technology have extended MEMS development towards radio frequency, microwave and millimeter wave applications. The need for micro-machining and MEMS based systems for RF and microwave applications arises from the inherent limitations of existing RF devices. Motivation for incorporating MEMS based fabrication technologies into microwave and millimeter wave systems can be classified into three main categories: precision, system integration and performance. As frequency increases, the size of RF components …

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Preparation Of Pyramidal Zinc Oxide Particle As An Antireflective Coating For Application In Solar Cell., Amit Banik Jan 2009

Preparation Of Pyramidal Zinc Oxide Particle As An Antireflective Coating For Application In Solar Cell., Amit Banik

Electrical Engineering Theses - Archive

There is a lot of research going on in the field of solar cell to increase the energy conversion efficiency. Many new methods have been implemented and new processes and materials have been suggested in the recent past. This research deals with the preparation of pyramidal structure zinc oxide particles as an antireflective coating for polycrystalline and non-silicon solar cell. The process involved a cost effective method that is electrochemical deposition of zinc oxide on silicon mold. The mold, inverted pyramid, is prepared by photolithographic process PECVD silicon nitride as the hard mask and wet etching and then electrochemical deposition …

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Design Of Microwave Non-Redundant Band-Pass Filter Using Microstrip And Edge Coupled Sections, Vinoj Vijayan Pillai Jan 2009

Design Of Microwave Non-Redundant Band-Pass Filter Using Microstrip And Edge Coupled Sections, Vinoj Vijayan Pillai

Electrical Engineering Theses - Archive

Microwave filler design using the non-redundant method relies on using the quarter wave Unit Elements (U.E's) to create a complex pole and hence augment the filter skirt response as against the redundant method wherein the U.E's do not contribute towards the filtering action. Filters realized using this method may have series high impedance capacitors, which are not realizable in planar microstrip technology. This thesis proposes a method to integrate microstrip transmission line and coupled line elements to circumvent the problem of realizing series capacitance. The total number of transmission line elements required to realize the filter is the minimum number …

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Performance Analysis Of Space - Time Block Coded Multiple Antenna Systems, Varsha Rao Bolar Jan 2009

Performance Analysis Of Space - Time Block Coded Multiple Antenna Systems, Varsha Rao Bolar

Electrical Engineering Theses - Archive

Multiple input and multiple output(MIMO) communications are seen as key technology to achieve high data rates for next generation of air interfaces like Wifi, WiMAX, and 3GPP-LTE, because of the spatial dimension complementing time (TDM), frequency (FDM), and code (CDM) multiple access technologies. MIMO technology has many captivating characteristics such as, it offers significant increases in data throughput and link range without additional bandwidth or transmit power. It achieves this by higher spectral efficiency (more bits per second per hertz of bandwidth) and diversity (reduced fading). Because of these properties, MIMO is a current theme of international wireless research. Diversity …

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A Portable Biotelemeter For Batteryless Gerd Sensors, Sandeep Battula Jan 2009

A Portable Biotelemeter For Batteryless Gerd Sensors, Sandeep Battula

Electrical Engineering Theses - Archive

In many medical problems, a continuous monitoring of the disease in vivo is essential to prevent further deterioration of health. The monitoring usually exceeds 24 hours. With the help of current advanced technologies, micro-medical devices are built to sense the internal physiological conditions in patients. Telemetry is used to transmit information to an external monitoring device. For the convenience and comfort of the patient, these monitoring systems should have low power consumption and be portable. This work discusses the design of a low power portable biotelemeter for batteryless Gastro esophageal reflux disease (GERD) sensors which can detect acid and non-acid …

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Analysis And Modeling Of Self Heating In Silicon Germanium Heterojunction Bipolar Transistors, Kevin Bastin Jan 2009

Analysis And Modeling Of Self Heating In Silicon Germanium Heterojunction Bipolar Transistors, Kevin Bastin

Electrical Engineering Theses - Archive

Silicon Germanium (SiGe) hetero junction bipolar transistors (HBTs) have established itself as strong technology contender for a host of circuit applications including analog, mixed signal and Radio Frequency (RF). Due to the effect of technology scaling, self heating plays a significant role in the performance of SiGe HBTs. This thesis paper does an extensive analysis on the effect of self heating and uses different methods to extract the self heating parameters. An expression for thermal resistance considering thermal conductivity as a function of temperature is derived. Also a method to convert a multi pole thermal model to a single pole …

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Preliminary Investigation Of Six Degree Of Freedom Human Steadiness Measurement Using A Performance Theory Framework, Jonathan Daniel Armstrong Jan 2009

Preliminary Investigation Of Six Degree Of Freedom Human Steadiness Measurement Using A Performance Theory Framework, Jonathan Daniel Armstrong

Electrical Engineering Theses - Archive

Tremor is an undesired oscillatory movement of a body segment which limits a person's ability to accomplish tasks. A conceptually sound, single number measure reflecting steadiness (defined as the inverse of tremor) of body segment is desired. Technology has advanced to make six degree of freedom (DOF) characterization of motion feasible, but the challenge remains regarding how to process time series data from multiple DOFs to achieve the single number composite measure. Previous conceptual work has applied General Systems Performance Theory (GSPT) to this problem. This thesis reports the investigation of steadiness composite measure formation. Three composite formation candidates were …

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Analysis Of The Spatial Correlation Measurements For The Multiple Input Multiple Output (Mimo) Channel Using Anechoic Chamber Measurement Methodologies To Evaluate Over-The-Air (Ota) Testing Techniques, Digvijay Arjunrao Jadhav Jan 2009

Analysis Of The Spatial Correlation Measurements For The Multiple Input Multiple Output (Mimo) Channel Using Anechoic Chamber Measurement Methodologies To Evaluate Over-The-Air (Ota) Testing Techniques, Digvijay Arjunrao Jadhav

Electrical Engineering Theses - Archive

There are numerous constraints in defining an Over-The-Air (OTA) test due to the practical hardware restrictions present in an anechoic chamber. It is necessary to evaluate the test signals used in OTA testing to verify that the real world multipath propagation can be recreated for OTA testing inside an anechoic chamber. The objective of this measurement is to check whether the parameter, `Spatial Correlation' can be used to compare OTA test signals used in the MIMO OTA testing. Spatial Correlation has prime importance from the point of view of MIMO channel modeling. It's a key factor in determining the MIMO …

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Error Concealment Techniques In H.264/Avc For Video Transmission Over Wireless Networks, Vineeth Shetty Kolkeri Jan 2009

Error Concealment Techniques In H.264/Avc For Video Transmission Over Wireless Networks, Vineeth Shetty Kolkeri

Electrical Engineering Theses - Archive

Several error concealment methods are applied to H.264/AVC (Advanced Video Coding) baseline profile such that the decoded video is error free. The error concealment techniques are implemented both in the spatial and temporal domains. The original and error concealment video sequences are compared in terms of MSE (Mean Square Error), PSNR (Peak-to-peak Signal to Noise Ratio) and SSIM (Structural Similarity Index Metric). This comparision has demonstrated that the error concealment methods are very effective in improving the visual quality. Implementation complexity also has been considered as the video transmission in baseline profile is meant for wireless networks.

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An Efficient Piecewise Linear Network, Rohit Rawat Jan 2009

An Efficient Piecewise Linear Network, Rohit Rawat

Electrical Engineering Theses - Archive

A Piecewise Linear Network (PLN) is a local network that offers the accuracy of higher order networks and the Multi Layer Perceptron (MLP), with the computational simplicity of linear networks. A method to design a PLN is demonstrated and several clustering algorithms, used in the design procedure, are compared. The performance of the Self Organizing Map (SOM) clustering algorithm has been found to be slightly better than the other clustering methods. Methods to determine the appropriate threshold in the Sequential Leader algorithm have been studied. A binary search based approach was found to be the most efficient in terms of …

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A Frequency Domain Approach For Time-Reversal Of Microwave Impulses, Shaoshu Sha Jan 2009

A Frequency Domain Approach For Time-Reversal Of Microwave Impulses, Shaoshu Sha

Electrical Engineering Theses - Archive

In this thesis, a compact and low-cost electronic circuit system is designed for time-reversal of microwave impulses with nanosecond and sub-nanosecond temporal durations. A frequency domain approach is adopted in order to avoid high sampling rate in time. The proposed system obtains the discrete spectra of input impulses first, then realizes time-reversal in frequency domain, and finally synthesizes the time-reversed impulses using discrete continuous wave elements. It is composed of commercially available circuits including oscillators, mixers/multipliers, band-pass-filters, amplifiers, and switches, hence embodies low-cost system-on-chip implementation. The proposed time-reversal circuit's performance is verified by Advanced Design System (ADS) simulations, with most …

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Utilizing Physical Layer Information To Improve Rfid Tag Identification, Rushikesh Shree Khasgiwale Jan 2009

Utilizing Physical Layer Information To Improve Rfid Tag Identification, Rushikesh Shree Khasgiwale

Electrical Engineering Theses - Archive

Radio-frequency identification (RFID) systems are designed for fast and accurate identification of multiple RFID tags. Their performance depends on the effective detection andresolution of communication collisions caused by the presence of multiple tags in the reader's field. Present RFID protocols do not rely upon the received physical waveform obtainedduring a collision for either collision resolution or improved identification rate. This signal contains important information that is often ignored or otherwise discarded.In this thesis I analyze the physical layer information extracted from a collision waveform from the ISO-18000-6C protocol and identifypotentially performance enhancing information contained therein. Utilization of this information to …

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Athena - Rfid Tag Metrics, Amit Jain Jan 2009

Athena - Rfid Tag Metrics, Amit Jain

Electrical Engineering Theses - Archive

In this thesis we have developed a Metric which is a numerical value representing the readability and performance characteristic of an RFID tagged object. The metric value ranges from 0 -100 and is given a unit of Athena, where a higher number specifies a better performing tag. The major parameters on which the metric value depends are frequency at which RFID system is working, transmitted power by the reader, and the received signal strength from the tag. All the parameters used for the Metric evaluation are well within the FCC regulations for passive UHF RFID system. Choosing the best performing …

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Localization System For Uav/Ugv In Urban Environments, Vishal Savio Coelho Jan 2009

Localization System For Uav/Ugv In Urban Environments, Vishal Savio Coelho

Electrical Engineering Theses - Archive

An implementation of relative localization of wireless sensor nodes using a potential field method is presented in this work. The system is designed to assist in UAV/UGV navigation in urban environments like rooms and passageways of buildings. An unmanned vehicle will need to rely on ground-based sensors to help it navigate indoors, as GPS signals are severely attenuated and reception is intermittent.A sufficient number of sensors are first deployed throughout the terrain in a random fashion. They must then localize themselves to the environment, i.e. they must develop an internal frame of reference or co-ordinate system. A potential field method …

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Real-Time Reconfiguration Of Programmable Logic Controller Communication Paths, Curtis Alan Parrott Jan 2009

Real-Time Reconfiguration Of Programmable Logic Controller Communication Paths, Curtis Alan Parrott

Masters Theses

"This thesis explores the topics related to reconfiguration of Programmable Logic Controller's (PLC's) communications paths as it relates to network security and reliability. These paths are normally fixed, which creates a single fault point which can easily be disrupted by network failure or network based attack. With the ability for autonomous communications path reconfiguration these disruptions in communications can be avoided or bypassed. This work builds on these principles and a series of PLC programs are developed to facilitate several things: Scanning of the three different network types most common in PLC to PLC communications; a comprehensive network scan routine …

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Numerical Modeling Of The Constraint Effects On Cleavage Fracture Toughness, Sunil Prakash, Xiaosheng Gao, T. S. Srivatsan Jan 2009

Numerical Modeling Of The Constraint Effects On Cleavage Fracture Toughness, Sunil Prakash, Xiaosheng Gao, T. S. Srivatsan

Mechanical Engineering Faculty Research

Cleavage fracture has been an important subject for engineers primarily because of its catastrophic nature and consequences. Experimental studies of cleavage fracture did reveal a considerable amount of scatter and provided evidence of noticeable constraint effects. This did provide the motivation for the development of statistical-based and micromechanics-based methods in order to both study and analyze the problem. The Weibull stress model, which is based on the weakest link statistics, uses two parameters (m and σ u) to effectively describe the inherent distribution of the micro-scale cracks once plastic deformation has occurred and to concurrently define the relationship between the …

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The Impact Of Communication Medium On Team Performance Patterns, Pilar Pazos, Mario G. Beruvides Jan 2009

The Impact Of Communication Medium On Team Performance Patterns, Pilar Pazos, Mario G. Beruvides

Engineering Management & Systems Engineering Faculty Publications

The increased impact of globalization and rapidly changing technologies are some of the biggest challenges facing 21st century organizations. Remote teams supported through computer-based systems have been identified as a key lever to help organizations adapt to this turbulent environment. This study sheds some light on how teams perform and adapt by evaluating performance and synergy over time for teams in two different settings: computer supported and face-to-face. Participants in the study were randomly assigned either to a computer-supported or a face-to face group. Each group met over three sessions to perform a series of tasks that were evaluated using …

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Fundamental Frequency Switching Strategies Of A Seven-Level Hybrid Cascaded H-Bridge Multilevel Inverter, Zhong Du, Leon M. Tolbert, Burak Ozpineci, John N. Chiasson Jan 2009

Fundamental Frequency Switching Strategies Of A Seven-Level Hybrid Cascaded H-Bridge Multilevel Inverter, Zhong Du, Leon M. Tolbert, Burak Ozpineci, John N. Chiasson

Electrical and Computer Engineering Faculty Publications and Presentations

This paper presents a cascaded H-bridge multilevel inverter that can be implemented using only a single dc power source and capacitors. Standard cascaded multilevel inverters require n dc sources for 2n + 1 levels. Without requiring transformers, the scheme proposed here allows the use of a single dc power source (e.g., a battery or a fuel cell stack) with the remaining n − 1 dc sources being capacitors, which is referred to as hybrid cascaded H-bridge multilevel inverter (HCMLI) in this paper. It is shown that the inverter can simultaneously maintain the dc voltage level of the capacitors and …

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An Affordable Software Defined Radio, Thad B. Welch, Travis Kent, Cameron H. G. Wright, Michael G. Morrow Jan 2009

An Affordable Software Defined Radio, Thad B. Welch, Travis Kent, Cameron H. G. Wright, Michael G. Morrow

Electrical and Computer Engineering Faculty Publications and Presentations

This paper discusses the utilization of a relatively inexpensive wideband radio receiver in combination with a digital downconverter (DDC) based data recorder to capture and record real world radio signals. The resulting in-phase (I) and quadrature (Q) data files are then imported intoMATLAB for processing. This batch processing of real world radio signals allows for a tremendous amount of classroom flexibility in the discussion of software defined radio topics.

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Pre-Processing Of Degraded Printed Documents By Non-Local Means And Total Variation, Laurence Likforman-Sulem, Jérôme Darbon, Elisa Barney Smith Jan 2009

Pre-Processing Of Degraded Printed Documents By Non-Local Means And Total Variation, Laurence Likforman-Sulem, Jérôme Darbon, Elisa Barney Smith

Electrical and Computer Engineering Faculty Publications and Presentations

We compare in this study two image restoration approaches for the pre-processing of printed documents: namely the Non-local Means filter and a total variation minimization approach. We apply these two ap- proaches to printed document sets from various periods, and we evaluate their effectiveness through character recognition performance using an open source OCR. Our results show that for each document set, one or both pre-processing methods improve character recog- nition accuracy over recognition without preprocessing. Higher accuracies are obtained with Non-local Means when characters have a low level of degradation since they can be restored by similar neighboring parts of …

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Online Identification Of The Rotor Time Constant Of An Induction Machine, Ahmed Oteafy, John Chiasson, Marc Bodson Jan 2009

Online Identification Of The Rotor Time Constant Of An Induction Machine, Ahmed Oteafy, John Chiasson, Marc Bodson

Electrical and Computer Engineering Faculty Publications and Presentations

Indirect field oriented control of an induction machine requires knowledge of the rotor time constant to estimate the rotor flux linkages. An online method is described for estimating the rotor time constant and the stator resistance both of which vary during operation of the machine due to ohmic heating. The method formulates the problem using a nonlinear least-squares criterion and is guaranteed to find the minimizing solution (parameter values) in a finite number of steps. In this work the algorithm has been implemented online in simulation with the results demonstrating its application and efficacy.

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High Dynamic Performance Programmed Pwm Control Of A Multilevel Inverter With Capacitor Dc Sources, John Chiasson, Zhong Du, Burak Özpineci, Leon M. Tolbert Jan 2009

High Dynamic Performance Programmed Pwm Control Of A Multilevel Inverter With Capacitor Dc Sources, John Chiasson, Zhong Du, Burak Özpineci, Leon M. Tolbert

Electrical and Computer Engineering Faculty Publications and Presentations

A cascade multilevel inverter consisting of a standard 3-leg inverter supplied by a DC source and three full H-bridges each supplied by a capacitor is considered for use as a motor drive. The capacitor H-bridges can only supply reactive voltage to the motor while the standard three leg inverter can supply both reactive and active voltage. A switching control algorithm is presented that shows this inverter topology can be used as an AC drive achieving considerable performance advantages (e.g., higher motor speed) compared to using a standard 3-leg inverter while at the same time regulating the capacitor voltages. The converter …

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Lyapunov Stability Of An Open-Loop Induction Machine, Ahmed Oteafy, John Chiasson Jan 2009

Lyapunov Stability Of An Open-Loop Induction Machine, Ahmed Oteafy, John Chiasson

Electrical and Computer Engineering Faculty Publications and Presentations

The induction machine is widely utilized in the industry and exists in a plethora of applications. Although it is characterized by its inherent stability over a wide range of operating conditions, this characterization is based on steadystate arguments. This work develops a rigorous approach to the open-loop stability of the induction machine. In particular, a condition for the global asymptotic stability of the induction machine in the sense of Lyapunov is presented. These conditions are met if the machine is lightly loaded. Hence, meeting these conditions guarantees that the motor will reach (or return to) the desired equilibrium point regardless …

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Study Of Ingaas Ldmos For Power Conversion Applications, Yidong Liu Jan 2009

Study Of Ingaas Ldmos For Power Conversion Applications, Yidong Liu

Electronic Theses and Dissertations

In this work an n-channel In0.65Ga0.35As LDMOS with Al2O3 as gate dielectric is investigated. Instead of using traditional Si process for LDMOS, we suggest In0.65Ga0.35As as substitute material due to its higher electron mobility and its promising for power applications. The proposed 0.5-µm channel-length LDMOS cell is studied through device TCAD simulation tools. Due to different gate dielectric, comprehensive comparisons between In0.65Ga0.35As LDMOS and Si LDMOS are made in two ways, structure with the same cross-sectional dimension, and structure with different thickness of gate dielectric to achieve the same gate capacitance. The on-resistance of the new device shows a big …

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Solar And Fuel Cell Circuit Modeling, Analysis And Integrations With Power Conversion Circuits For Distributed Generation, Smitha Krishnamurthy Jan 2009

Solar And Fuel Cell Circuit Modeling, Analysis And Integrations With Power Conversion Circuits For Distributed Generation, Smitha Krishnamurthy

Electronic Theses and Dissertations

Renewable energy is considered to be one of the most promising alternatives for the growing energy demand in response to depletion of fossil fuels and undesired global warming issue. With such perspective, Solar Cells and Fuel Cells are most viable, environmentally sound, and sustainable energy sources for power generation. Solar and Fuel cells have created great interests in modern applications including distributed energy generation to provide clean energy. The purpose of this thesis was to perform a detailed analysis and modeling of Solar and Fuel cells using Cadence SPICE, and to investigate dynamic interactions between the modules and power conversion …

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Embedded Magnetics For Power System On Chip (Psoc), Jian Lu Jan 2009

Embedded Magnetics For Power System On Chip (Psoc), Jian Lu

Electronic Theses and Dissertations

A novel concept of on-chip bondwire inductors and transformers with ferrite epoxy glob coating is proposed, offering a cost effective approach to realize power systems on chip (PSoC) or System-in-Package (PSiP). The concept has been investigated both experimentally and with finite element modeling. Improvement in total inductance is demonstrated for multi-turn bondwire inductors over single bondwire inductors. The inductance and Q factor can be further boosted with coupled multi-turn inductor concept. Transformer parameters including self- and mutual inductance, and coupling factors are extracted from both modeled and measured S-parameters. More importantly, the bondwire magnetic components can be easily integrated into …

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Level-Of-Service And Traffic Safety Relationship: An Exploratory Analysis Of Signalized Intersections And Multiland High-Speed Arterial Corridors, Ana Almonte-Valdivia Jan 2009

Level-Of-Service And Traffic Safety Relationship: An Exploratory Analysis Of Signalized Intersections And Multiland High-Speed Arterial Corridors, Ana Almonte-Valdivia

Electronic Theses and Dissertations

Since its inception in 1965, the Level-of-Service (LOS) has proved to be an important and practical "quality of service" indicator for transportation facilities around the world, widely used in the transportation and planning fields. The LOS rates these facilities' traffic operating conditions through the following delay-based indicators (ordered from best to worst conditions): A, B, C, D, E and F. This LOS rating has its foundation on quantifiable measures of effectiveness (MOEs) and on road users' perceptions; altogether, these measures define a LOS based on acceptable traffic operating conditions for the road user, implying that traffic safety is inherent to …

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Robust Estimation And Adaptive Guidance For Multiple Uavs' Cooperation, Randal Allen Jan 2009

Robust Estimation And Adaptive Guidance For Multiple Uavs' Cooperation, Randal Allen

Electronic Theses and Dissertations

In this paper, an innovative cooperative navigation method is proposed for multiple Unmanned Air Vehicles (UAVs) based on online target position measurements. These noisy position measurement signals are used to estimate the target's velocity for non-maneuvering targets or the target's velocity and acceleration for maneuvering targets. The estimator's tracking capability is physically constrained due to the target's kinematic limitations and therefore is potentially improvable by designing a higher performance estimator. An H-infinity filter is implemented to increase the robustness of the estimation accuracy. The performance of the robust estimator is compared to a Kalman filter and the results illustrate more …

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An Analogy Based Costing System For Injection Molds Based Upon Geometry Similarity With Wavelets, Cyrus Clinton Hillsman Jan 2009

An Analogy Based Costing System For Injection Molds Based Upon Geometry Similarity With Wavelets, Cyrus Clinton Hillsman

Electronic Theses and Dissertations

The injection molding industry is large and diversified. However there is no universally accepted way to bid molds, despite the fact that the mold and related design comprise 50% of the total cost of an injection-molded part over its lifetime. This is due to both the structure of the industry and technical difficulties in developing an automated and practical cost estimation system. The technical challenges include lack of a common data format for both parts and molds; the comprehensive consideration of the data about a wide variety of mold types, designs, complexities, number of cavities and other factors that directly …

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System And Method For Quantitative Imaging Of Chemical Composition To Decompose More Than Two Materials, Xin Liu, L. Yu, C. H. Mccollough Jan 2009

System And Method For Quantitative Imaging Of Chemical Composition To Decompose More Than Two Materials, Xin Liu, L. Yu, C. H. Mccollough

Nuclear Engineering and Radiation Science Faculty Research & Creative Works

A system and method for decomposing more than two materials in an imaging object includes performing a CT imaging acquisition of a portion of an imaging object using at least two energy levels to acquire imaging data associated with each of the at least two energy levels. A total mass attenuation of the imaging data is expressed as a weighted sum of constituent element mass attenuation coefficients and an effective atomic number and density of the constituent elements in the portion of the imaging object is determined by one of a number of methods. Accordingly, concentration of the constituent elements …

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