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Missouri University of Science and Technology

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Articles 10861 - 10890 of 21795

Full-Text Articles in Engineering

Optimal Neuro-Controller Synthesis For Variable-Time Impulse Driven Systems, Xiaohua Wang, S. N. Balakrishnan Jun 2008

Optimal Neuro-Controller Synthesis For Variable-Time Impulse Driven Systems, Xiaohua Wang, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper develops a systematic scheme to solve for the optimal controls of variable time impulsive systems. First, the optimality conditions for variable time impulse driven systems are derived using the calculus of variation. After wards, a neural network based adaptive critic method is proposed to numerically solve the two-point boundary value problems formulated based on the optimality conditions derived. Finally, two examples - one linear and one nonlinear - are presented to illustrate the conditions derived and to show the power of the neural network based adaptive critic method proposed.

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Towards Spike-Based Speech Processing: A Biologically Plausible Approach To Simple Acoustic Classification, Ismail Uysal, Harsha Sathyendra, John G. Harris Jun 2008

Towards Spike-Based Speech Processing: A Biologically Plausible Approach To Simple Acoustic Classification, Ismail Uysal, Harsha Sathyendra, John G. Harris

Electrical and Computer Engineering Faculty Research & Creative Works

Shortcomings of automatic speech recognition (ASR) applications are becoming more evident as they are more widely used in real life. The inherent non-stationarity associated with the timing of speech signals as well as the dynamical changes in the environment make the ensuing analysis and recognition extremely difficult. Researchers often turn to biology seeking clues to make better engineered systems, and ASR is no exception with the usage of feature sets such as Mel frequency cepstral coefficients, which employ filter banks similar to cochlear filter banks in frequency distribution and bandwidth. In this paper, we delve deeper into the mechanics of …

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Improving Steel Cleanliness Through Slag Refining, Sarina Bao, Xinhua Wang, Lifeng Zhang, Shufeng Yang, Kent D. Peaslee May 2008

Improving Steel Cleanliness Through Slag Refining, Sarina Bao, Xinhua Wang, Lifeng Zhang, Shufeng Yang, Kent D. Peaslee

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.

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Bubble Dynamics Investigation In A Slurry Bubble Column, Chengtian Wu, Kelsey Suddard, Muthanna H. Al-Dahhan May 2008

Bubble Dynamics Investigation In A Slurry Bubble Column, Chengtian Wu, Kelsey Suddard, Muthanna H. Al-Dahhan

Chemical and Biochemical Engineering Faculty Research & Creative Works

The Application of Four-Point Optical Probe Has Been for the First Time Extended to a Slurry System in a 10.2-Cm ID Column. Bubble Dynamics (Local Gas Holdup, Bubble Chord Length, Bubble Velocity, Bubble Frequency, and Specific Interfacial Area) Were Investigated using an Air-Water-Catalyst System under Atmospheric Pressure. with an Increase in Solids Loading, the Local Gas Holdup, Specific Interfacial Area, and Bubble Frequency Decreased, While the Bubble Velocity Changed Slightly. Bubble Chord Length Increased Noticeably, and the Bubble Chord Length Distribution Spread More Widely at High Solids Loading. It Has Also Been Found that the Probe Orientation is Important for …

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Incorporation Of Evidences Into An Intelligent Computational Argumentation Network For A Web-Based Collaborative Engineering Design System, Xiaoqing Frank Liu, Ekta Khudkhudia, Ming-Chuan Leu May 2008

Incorporation Of Evidences Into An Intelligent Computational Argumentation Network For A Web-Based Collaborative Engineering Design System, Xiaoqing Frank Liu, Ekta Khudkhudia, Ming-Chuan Leu

Computer Science Faculty Research & Creative Works

Conflicts among the stakeholders are unavoidable in the process of collaborative engineering design. Resolution of these conflicts is a challenging task. In our previous research, a web based intelligent collaborative system was developed which provides decision-making support, using computational argumentation techniques. Enhancements were done to this system to incorporate the priorities of the stakeholders and to detect arguments that self conflict. As an effort to make this system more effective and more objective in the process of decision making, we develop a method to assess the effect of evidences in the argumentation network, using Dempster-Shafer theory of evidence and fuzzy …

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Susceptibility Scanning As Failure Analysis Tool For System-Level Electrostatic Discharge (Esd) Problems, Giorgi Muchaidze, Jayong Koo, Qing Cai, Tun Li, Lijun Han, Andrew Martwick, Kai Wang, Jin Min, James L. Drewniak, David Pommerenke May 2008

Susceptibility Scanning As Failure Analysis Tool For System-Level Electrostatic Discharge (Esd) Problems, Giorgi Muchaidze, Jayong Koo, Qing Cai, Tun Li, Lijun Han, Andrew Martwick, Kai Wang, Jin Min, James L. Drewniak, David Pommerenke

Electrical and Computer Engineering Faculty Research & Creative Works

Susceptibility scanning is an increasingly adopted method for root cause analysis of system-level immunity sensitivities. It allows localizing affected nets and integrated circuits (ICs). Further, it can be used to compare the immunity of functionally identical or similar ICs or circuit boards. This paper explains the methodology as applied to electrostatic discharge and provides examples of scan maps and signals probed during immunity scanning. Limitations of present immunity analysis methods are discussed.

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Clustering Of High-Dimensional Gene Expression Data With Feature Filtering Methods And Diffusion Maps, Rui Xu, Steven Damelin, Boaz Nadler, Donald C. Wunsch May 2008

Clustering Of High-Dimensional Gene Expression Data With Feature Filtering Methods And Diffusion Maps, Rui Xu, Steven Damelin, Boaz Nadler, Donald C. Wunsch

Electrical and Computer Engineering Faculty Research & Creative Works

The importance of gene expression data in cancer diagnosis and treatment by now has been widely recognized by cancer researchers in recent years. However, one of the major challenges in the computational analysis of such data is the curse of dimensionality, due to the overwhelming number of measures of gene expression levels versus the small number of samples. Here, we use a two-step method to reduce the dimension of gene expression data. At first, we extract a subset of genes based on the statistical characteristics of their corresponding gene expression measurements. For further dimensionality reduction, we then apply diffusion maps, …

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Electron And Spin Transport In The Presence Of A Complex Absorbing Potential, Fatih Dogan, Wonkee Kim, C. Blois, Frank Marsiglio May 2008

Electron And Spin Transport In The Presence Of A Complex Absorbing Potential, Fatih Dogan, Wonkee Kim, C. Blois, Frank Marsiglio

Materials Science and Engineering Faculty Research & Creative Works

We examine the impact of a complex absorbing potential on electron transport both in the continuum and on a lattice. This requires the use of non-Hermitian Hamiltonians; the required formalism is briefly outlined. The lattice formulation allows us to study the interesting problem of an electron interacting with a stationary spin and the subsequent time evolution of the electron and spin properties as the electron is absorbed after the initial interaction. Remarkably, the properties of the localized spin are affected “at a distance” by the interaction of the (now entangled) electron with a complex potential.

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Effect Of Shear On Performance And Microbial Ecology Of Continuously Stirred Anaerobic Digesters Treating Animal Manure, Rebecca A. Hoffmann, Marcelo L. Garcia, Mehul Veskivar, Khursheed Karim, Muthanna H. Al-Dahhan, Largus T. Angenent May 2008

Effect Of Shear On Performance And Microbial Ecology Of Continuously Stirred Anaerobic Digesters Treating Animal Manure, Rebecca A. Hoffmann, Marcelo L. Garcia, Mehul Veskivar, Khursheed Karim, Muthanna H. Al-Dahhan, Largus T. Angenent

Chemical and Biochemical Engineering Faculty Research & Creative Works

We Determined the Effect of Different Mixing Intensities on the Performance, Methanogenic Population Dynamics, and Juxtaposition of Syntrophic Microbes in Anaerobic Digesters Treating Cow Manure from a Dairy Farm. Computer Automated Radioactive Particle Tracking in Conjunction with Computational Fluid Dynamics Was Performed to Quantify the Shear Levels Locally. Four Continuously Stirred Anaerobic Digesters Were Operated at Different Mixing Intensities of 1,500, 500, 250, and 50 Revolutions Per Min (RPM) over a 260-Day Period at a Temperature of 34 ± 1°C. Animal Manure at a Volatile Solids (VS) Concentration of 50 G/L Was Fed into the Digesters Daily at Five Different …

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Channel Estimation For Ofdm Systems In The Presence Of Carrier Frequency Offset And Phase Noise, Jun Tao, Jingxian Wu, Chengshan Xiao May 2008

Channel Estimation For Ofdm Systems In The Presence Of Carrier Frequency Offset And Phase Noise, Jun Tao, Jingxian Wu, Chengshan Xiao

Electrical and Computer Engineering Faculty Research & Creative Works

Channel estimation for orthogonal frequency division multiplexing (OFDM) system at the presence of carrier frequency offset (CFO) and phase noise is discussed in this paper. A CFO estimation algorithm is developed by exploiting the time-frequency structure of training symbols, and it provides a very accurate estimation of CFO at the presence of both unknown frequency selective fading and phase noise. Based on the estimated CFO, the phase noise and frequency selective fading are jointly estimated by employing the maximum a posteriori (MAP) criterion. Specifically, the fading channel is estimated in the form of frequency domain channel transfer function (CTF). The …

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Zeolite Thin Film-Coated Long Period Fiber Grating Sensor For Measuring Trace Chemical, Jian Zhang, Xiling Tang, Junhang Dong, Tao Wei, Hai Xiao May 2008

Zeolite Thin Film-Coated Long Period Fiber Grating Sensor For Measuring Trace Chemical, Jian Zhang, Xiling Tang, Junhang Dong, Tao Wei, Hai Xiao

Electrical and Computer Engineering Faculty Research & Creative Works

This paper reports the development of a new zeolite thin film-coated long period fiber grating (LPFG) sensor for direct measurement of trace organic vapors. The sensor was fabricated by growing pure silica MFI-type zeolite thin film on the optical fiber grating by in situ hydrothermal crystallization. The sensor measures chemical vapor concentration by monitoring the molecular adsorption-induced shift of LPFG resonant wavelength in near infrared (IR) region. Upon loading analyte molecules, the zeolite's refractive index changes in the close vicinity of the fiber index where the LPFG has a large response to achieve high sensitivity.

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A Novel 24 Ghz One-Shot, Rapid And Portable Microwave Imaging System, Mohammad Tayeb Ahmad Ghasr, Mohamed A. Abou-Khousa, Sergey Kharkovsky, R. Zoughi, David Pommerenke May 2008

A Novel 24 Ghz One-Shot, Rapid And Portable Microwave Imaging System, Mohammad Tayeb Ahmad Ghasr, Mohamed A. Abou-Khousa, Sergey Kharkovsky, R. Zoughi, David Pommerenke

Electrical and Computer Engineering Faculty Research & Creative Works

Development of microwave and millimeter wave imaging systems has received significant attention in the past decade. Signals at these frequencies penetrate inside of dielectric materials and have relatively small wavelengths. Thus, imaging systems at these frequencies can produce images of the dielectric and geometrical distributions of objects. Although there are many different approaches for imaging at these frequencies, they each have their respective advantageous and limiting features (hardware, reconstruction algorithms). One method involves electronically scanning a given spatial domain while recording the coherent scattered field distribution from an object. Consequently, different reconstruction or imaging techniques may be used to produce …

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An Experimental Investigation Of Higher Order Mode Suppression In Tem Cells, Shaowei Deng, David Pommerenke, Todd H. Hubing, Dongshik Shin May 2008

An Experimental Investigation Of Higher Order Mode Suppression In Tem Cells, Shaowei Deng, David Pommerenke, Todd H. Hubing, Dongshik Shin

Electrical and Computer Engineering Faculty Research & Creative Works

Transverse electromagnetic (TEM) cells can be used to evaluate the electric and magnetic fields coupling from integrated circuits (ICs). The propagation and reflection of higher order modes in the cells limits the bandwidth of TEM cells. This paper investigates several methods for suppressing higher order modes in TEM cells in order to extend the applicable frequency range without changing the test topology. Numerical models and measurements of a modified TEM cell demonstrate how higher order mode suppression techniques can extend the useful frequency range of a TEM cell for IC measurements from 1 to 2.5 GHz.

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Improved Frequency-Domain Channel Estimation For Fast Time-Varying Mimo-Scfde Channels, Y. Rosa Zheng, Jian Zhang May 2008

Improved Frequency-Domain Channel Estimation For Fast Time-Varying Mimo-Scfde Channels, Y. Rosa Zheng, Jian Zhang

Electrical and Computer Engineering Faculty Research & Creative Works

A frequency-domain channel estimation method is proposed for time-varying multiple-input multiple output (MIMO) single-carrier frequency-domain equalization (SC-FDE). The proposed method uses frequency-domain interpolation to obtain channel frequency responses of data blocks from estimated responses of two adjacent pilot blocks. It takes the channel temporal-spatial correlation into account to achieve minimum mean squared error (MMSE) estimation, thus improving the accuracy and effectiveness in high Doppler scenarios. The simulation results of the bit error rate (BER) performances show that the proposed method works well for fast time-varying channels with Doppler spread as high as 300 Hz while maintaining over 70% data efficiency.

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Channel Equalization And Symbol Detection For Single Carrier Broadband Mimo Systems With Multiple Carrier Frequency Offsets, Chengshan Xiao, Y. Rosa Zheng May 2008

Channel Equalization And Symbol Detection For Single Carrier Broadband Mimo Systems With Multiple Carrier Frequency Offsets, Chengshan Xiao, Y. Rosa Zheng

Electrical and Computer Engineering Faculty Research & Creative Works

We consider the frequency-domain channel equalization and symbol detection of multiple input multiple output (MIMO) single-carrier broadband wireless system in the presence of severe frequency-selective channel fading and multiple unknown carrier frequency offsets (CFOs). We show that the constellation of the equalized data is rotating due to multiple CFOs, therefore, the equalized data can not be reliably detected without removing the rotating phases caused by the multiple unknown CFOs. Instead of estimating the CFOs, we propose a method to estimate the rotating phases caused by multiple CFOs, remove the rotating phases from the equalized data, and perform symbol detection. Numerical …

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A Stabilizing, High-Performance Controller For Input Series-Output Parallel Converters, Jonathan W. Kimball, Joseph T. Mossoba, Philip T. Krein May 2008

A Stabilizing, High-Performance Controller For Input Series-Output Parallel Converters, Jonathan W. Kimball, Joseph T. Mossoba, Philip T. Krein

Electrical and Computer Engineering Faculty Research & Creative Works

A form of sensorless current mode (SCM) control stabilizes sharing in multiphase input-series-output-parallel (ISOP) dc-dc converter topologies. Previously, ISOP converters have been proposed to reduce the voltage and current ratings of switching devices. Since the inputs are all connected in series, each phase need only be rated for a fraction of the total input voltage. Voltage and current sharing are key - if there is any phase-to-phase imbalance, the system benefits are substantially reduced. In the present work, a simple SCM controller is shown to guarantee stable sharing. Each phase acts independently on the same output reference and desired input …

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A Variable Partitioning Strategy For The Multirate Method In Power Systems, Jingjia Chen, Mariesa Crow May 2008

A Variable Partitioning Strategy For The Multirate Method In Power Systems, Jingjia Chen, Mariesa Crow

Electrical and Computer Engineering Faculty Research & Creative Works

An application of the multirate method to differential and algebraic equations (DAEs) is discussed in this paper. Based on the specific formulation of the power systems algebraic equations, an effective algebraic variable partitioning strategy is developed and implemented. The application of the partitioning strategy to an example power system provides validation of the proposed partitioning strategy in terms of speed-up and accuracy.

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Using Tem Cell Measurements To Estimate The Maximum Radiation From Pcbs With Cables Due To Magnetic Field Coupling, Shaowei Deng, Todd H. Hubing, Daryl G. Beetner May 2008

Using Tem Cell Measurements To Estimate The Maximum Radiation From Pcbs With Cables Due To Magnetic Field Coupling, Shaowei Deng, Todd H. Hubing, Daryl G. Beetner

Electrical and Computer Engineering Faculty Research & Creative Works

Common-mode currents can be induced on cables attached to printed circuit boards (PCBs) due to electric and magnetic field coupling. This paper describes a technique for using transverse electromagnetic (TEM) cell measurements to obtain an effective common-mode voltage (or magnetic moment) that quantifies the ability of traces and integrated circuits on PCBs to drive common-mode currents onto cables due to magnetic field coupling. This equivalent common-mode voltage can be used to reduce the complexity of full-wave models that calculate the radiated emissions from a system containing the board. It can also be used without full-wave modeling to provide a …

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Novel Near-Field Microwave And Millimeter Wave Differential Probe Using A Dual-Modulated Single Aperture, Mohamed A. Abou-Khousa, R. Zoughi May 2008

Novel Near-Field Microwave And Millimeter Wave Differential Probe Using A Dual-Modulated Single Aperture, Mohamed A. Abou-Khousa, R. Zoughi

Electrical and Computer Engineering Faculty Research & Creative Works

A novel differential probe design is introduced in this paper for near-field microwave and millimeter wave non-destructive testing (NDT) and imaging applications. In such applications, the variations in the distance between the probing antenna and the structure under inspection, i.e., standoff distance, can potentially mask the signal of interest, and hence, adversely impact the detection capability of the probe. Differential near-field probes and compensation methods were developed in the past to null out the standoff distance variation effect from the measured signal. The available methods, however, suffer from some limitations such as using two balanced apertures or offering limited range …

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Multimodal Solution For A Rectangular Waveguide Radiating Into A Multilayered Dielectric Structure And Its Application For Dielectric Property And Thickness Evaluation, Mohammad Tayeb Ahmad Ghasr, R. Zoughi May 2008

Multimodal Solution For A Rectangular Waveguide Radiating Into A Multilayered Dielectric Structure And Its Application For Dielectric Property And Thickness Evaluation, Mohammad Tayeb Ahmad Ghasr, R. Zoughi

Electrical and Computer Engineering Faculty Research & Creative Works

Open-ended rectangular waveguides are widely used for microwave and millimeter wave nondestructive testing applications. Applications have included detecting disbonds and delaminations in multilayered composite structures, thickness evaluation of dielectric sheets and coatings on metal substrates, etc. When inspecting a complex multilayered composite structure, made of generally lossy dielectric layers with arbitrary thicknesses and backing, the dielectric properties of a particular layer within the structure is of particular interest, such being health monitoring of structures such as radomes. The same is also true where one may be interested in the thickness or more importantly thickness variation of a particular layer within …

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Potential Application Of The Modulated Scatterer Technique To Multilayered Material Evaluation And Health Monitoring, Kristen M. Munoz, Amy K. Perrey, R. Zoughi May 2008

Potential Application Of The Modulated Scatterer Technique To Multilayered Material Evaluation And Health Monitoring, Kristen M. Munoz, Amy K. Perrey, R. Zoughi

Electrical and Computer Engineering Faculty Research & Creative Works

Modulated scatterer technique (MST) is based on illuminating a small antenna, usually a dipole, loaded with a PIN diode, with an electromagnetic wave. The scattered (or reflected) wave from the probe may then be used to determine dielectric properties of the material in which the probe is located or embedded. The PIN diode is turned "on" and "off" which not only changes the impedance of the probe, but also modulates (with the same rate) the reflection from the probe. A major challenge associated with MST is detecting and distinguishing the desired probe response in the ever-present reflections from surrounding structures …

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Universal Electric And Magnetic Field Analyzer System, Yong Cheh Ho, David Pommerenke, Tun Li May 2008

Universal Electric And Magnetic Field Analyzer System, Yong Cheh Ho, David Pommerenke, Tun Li

Electrical and Computer Engineering Faculty Research & Creative Works

Near-field probing is often used to determine the sources and coupling paths of an electromagnetic interference problem above a printed circuit board or integrated circuits chip. A wideband universal field analyzer was developed in order to measure circularly and linearly polarized magnetic fields and total electric field in a rapid sequence using a single probe design.

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A Semi-Analytical Approach For System-Level Electrical Modeling Of Electronic Packages With Large Number Of Vias, Zaw Zaw Oo, En Xiao Liu, Er Ping Li, Xingchang Wei, Yaojiang Zhang, Mark Tan, Le Wei Joshua Li, Rüdiger Vahldieck May 2008

A Semi-Analytical Approach For System-Level Electrical Modeling Of Electronic Packages With Large Number Of Vias, Zaw Zaw Oo, En Xiao Liu, Er Ping Li, Xingchang Wei, Yaojiang Zhang, Mark Tan, Le Wei Joshua Li, Rüdiger Vahldieck

Electrical and Computer Engineering Faculty Research & Creative Works

This paper presents a semi-analytical approach for electrical performance modeling of complex electronic packages with multiple power/ ground planes and large number of vias. the method is based on the modal expansion technique and the method of moments. for the inner package domain with multiple power/ground planes and many vias, the modal expansion method is employed to compute the electromagnetic fields from which the multiport network parameters, e.g., the admittance matrix can be easily obtained. for the top/bottom domain of signal layers, the moment method is used to extract the equivalent resistance, inductance, capacitance, and conductance (RLCG) parameters. the equivalent …

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Integral Channels In Metal Components And Fabrication Thereof, Rajiv S. Mishra Apr 2008

Integral Channels In Metal Components And Fabrication Thereof, Rajiv S. Mishra

Materials Science and Engineering Faculty Research & Creative Works

An internal channel in a metal body for use in applications where internal fluid flow within a metal body is desired, as in a heat exchanger. The internal channel is formed in the metal body by frictionally stirring with a pin plunged into the metal body, and traversing the metal body with the pin.

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Design And Implementation Of Fpga Configuration Logic Block Using Asynchronous Semi-Static Ncl Circuits, Indira P. Dugganapally, Waleed K. Al-Assadi, Vijay Pillai, Scott C. Smith Apr 2008

Design And Implementation Of Fpga Configuration Logic Block Using Asynchronous Semi-Static Ncl Circuits, Indira P. Dugganapally, Waleed K. Al-Assadi, Vijay Pillai, Scott C. Smith

Electrical and Computer Engineering Faculty Research & Creative Works

This paper proposes the design of a FPGA configurable logic block (CLB) using asynchronous semi-static NULL convention logic (NCL) Library. The proposed design uses three semi-static LLT's for implementing NCL logic functions. Each LLT can be configured to function as any one of the 27 fundamental NCL Semi-Static gates. The proposed CLB supports 10 inputs and three different outputs, each with resettable and inverting variations. The CLB has two modes: Configuration mode and Operation mode. The Static NCL FPGA CLB is simulated at the transistor level using the 1.8 V, 180 nm TSMC CMOS process.

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Comparison Of An Experimental Bone Cement With Surgical Simplex® P, Spineplex® And Cortoss®, D. Boyd, Mark R. Towler, A. Wren, O. M. Clarkin Apr 2008

Comparison Of An Experimental Bone Cement With Surgical Simplex® P, Spineplex® And Cortoss®, D. Boyd, Mark R. Towler, A. Wren, O. M. Clarkin

Chemical and Biochemical Engineering Faculty Research & Creative Works

Conventional polymethylmethacrylate (PMMA) cements and more recently Bisphenol-a-glycidyl dimethacrylate (BIS-GMA) composite cements are employed in procedures such as vertebroplasty. Unfortunately, such materials have inherent drawbacks including, a high curing exotherm, the incorporation of toxic components in their formulations, and critically, exhibit a modulus mismatch between cement and bone. The literature suggests that aluminum free, zinc-based glass polyalkenoate cements (Zn-GPC) may be suitable alternative materials for consideration in such applications as vertebroplasty. This paper examines one formulation of Zn-GPC and compares its strengths, modulus, and biocompatibility with three commercially available bone cements, Spineplex®, Simplex® P and Cortoss®. The setting times indicate …

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Determination Of Creep Compliance And Tensile Strength Of Hot-Mix Asphalt For Wearing Courses In Missouri, David Newton Richardson, S. M. Lusher Apr 2008

Determination Of Creep Compliance And Tensile Strength Of Hot-Mix Asphalt For Wearing Courses In Missouri, David Newton Richardson, S. M. Lusher

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Creep compliance and indirect tensile (IDT) strength of hot-mix asphalt (HMA) are the two primary inputs to the low-temperature or thermal cracking module in the new Mechanistic-Empirical Pavement Design Guide (M-E PDG) software. Creep compliance is defined as time-dependent strain per unit stress, while IDT strength is best defined as HMA strength when subjected to tension. AASHTO T 322 test protocol was used as reference for this work. However in preparation for the laboratory work performed at the Missouri University of Science and Technology many experts were consulted as to how IDT creep/strength testing and calculations are actually being performed. …

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Natrolitite, An Unusual Rock -- Occurrence And Petrographic And Geochemical Characteristics (Eastern Turkey), Emin Ciftci, John Patrick Hogan, Hasan Kolayli, Emin Cadirli Apr 2008

Natrolitite, An Unusual Rock -- Occurrence And Petrographic And Geochemical Characteristics (Eastern Turkey), Emin Ciftci, John Patrick Hogan, Hasan Kolayli, Emin Cadirli

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Very unusual rocks consisting of natrolite (>95 vol.%) ± pargasite (<5 vol.%) and rare albite (<1 vol. %) have been discovered in the Kop mountain range, eastern Turkey. We propose to call these rocks 'natrolitite' and 'pargasite natrolitite'. They were produced by Na Si metasomatism of dikes and stocks of diorite through replacement of the intermediate primary igneous plagioclase to produce natrolite. The metasomatic alteration produced concentric elliptical zones characterized by distinct mineral assemblages centered on intrusions of diorite. The Central Zone 1 consists of variably albitized diorite with preserved magmatic textures (albite ± andesine ± pargasite ± quartz). Transition Zone 2 comprises natrolite-bearing diorite (natrolite ± albite ± andesine ± pargasite ± calcite ± quartz). Marginal Zone 3 is a rock made up almost entirely of natrolite (natrolite ± pargasite ± albite ± calcite ± chlorite). Outer Zone 4 occurs along the boundary between the natrolitite and the surrounding serpentinite and consists of listvenite, a rock which comprises magnesite, quartz, calcite, mica, talc, and hematite, indicating a role for CO2 in the metasomatic reactions, consistent with the presence of calcite in the alteration zones. Zone 5 consists essentially of brecciated serpentinite with numerous hydrothermal quartz veins and calcite veins. Whole-rock compositions document an increase in Na2O, Al2O3, and H2O from the core (central zone) to the margin while CaO, MgO, and SiO2 decrease. Plagioclase abundance and composition also varies outwards from the central core rocks where it occurs as a primary magmatic phase (~95 vol.% An41-38) …

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Off And Running, James D. Sterling Apr 2008

Off And Running, James D. Sterling

Business and Information Technology Faculty Research & Creative Works

No abstract provided.

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The Processing, Mechanical Properties And Bioactivity Of Strontium Based Glass Polyalkenoate Cements, Anthony Wren, Daniel Boyd, Mark R. Towler Apr 2008

The Processing, Mechanical Properties And Bioactivity Of Strontium Based Glass Polyalkenoate Cements, Anthony Wren, Daniel Boyd, Mark R. Towler

Chemical and Biochemical Engineering Faculty Research & Creative Works

The suitability of zinc-based glass polyalkenoate cements (GPCs) for use in orthopaedics can be improved by the substitution of strontium into the glass phase which should impart improved radiopacity and bone forming properties to the cements without retarding strength. The purpose of this research was to produce novel GPCs based on calcium-strontium-zinc-silicate glasses and to evaluate their mechanical properties and biocompatibility with the ultimate objective of developing a new range of cements for skeletal applications. Three glass compositions, based on incremental substitutions of strontium for calcium, were synthesized; BT100 (0.16CaO, 0.36ZnO, 0.48SiO2), BT101 (0.04SrO, 0.12CaO, 0.36ZnO, 0.48SiO2 …

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