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Articles 11731 - 11760 of 21751

Full-Text Articles in Engineering

Liquid Phase Mixing In Trayed Bubble Column Reactors, Javier Alvaré, Muthanna H. Al-Dahhan Mar 2006

Liquid Phase Mixing In Trayed Bubble Column Reactors, Javier Alvaré, Muthanna H. Al-Dahhan

Chemical and Biochemical Engineering Faculty Research & Creative Works

The Compartmentalization of Conventional Bubble Columns by Perforated Trays Constitutes a Very Effective Method to Reduce the Liquid Back mixing. the Effect of Tray Design and Operating Conditions on the overall Liquid Mixing Was Studied in a Bench-Scale Trayed Bubble Column. the Extent of Liquid Back mixing in the Column Was Investigated in Light of Liquid-Phase Tracer Response Experiments. in Average, a Three-Fold Reduction in the Liquid Back mixing Was Achieved in the Trayed Column as Compared to the Column Without the Trays. Moreover, the Tray Open Area and the Superficial Liquid Velocity Were Found to Have the Strongest Effects …

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Effect Of Water Ice Content On Excavatability Of Lunar Regolith, Leslie S. Gertsch, Robert Gustafson, Richard E. Gertsch Feb 2006

Effect Of Water Ice Content On Excavatability Of Lunar Regolith, Leslie S. Gertsch, Robert Gustafson, Richard E. Gertsch

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

The amount of water ice contained within prepared samples of JSC-1 lunar regolith simulant strongly affects the excavatability of the material. As part of a NASA Phase I SBIR project, load-penetration testing of JSC-1 lunar regolith simulant was performed at water ice concentrations ranging from zero to 11% by mass (approximately saturated), after compaction and cooling to simulate probable lunar conditions. After mixing dry JSC-1 simulant with the appropriate amount of water, the samples were individually compressed into containment rings under 48 MPa of pressure. Thermocouples embedded in the samples monitored internal temperature while they were cooled in a bath …

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Wagging The Contact Line: Transverse And Longitudinal Waves, S. Saritha, Partho Neogi Feb 2006

Wagging The Contact Line: Transverse And Longitudinal Waves, S. Saritha, Partho Neogi

Chemical and Biochemical Engineering Faculty Research & Creative Works

Kinetics of wetting has been explored where the contact line not only sees a steady spreading but also has longitudinal or transverse oscillations imposed on it. The latter case is realized when spreading takes place over a rough surface. The effects of the imposed motion are small, which seem to be due to low spreading rates and small dynamic contact angles used in this study. However, a singularity is seen in viscous dissipation during the movement on the model rough surface, which is interpreted here as an instability that is similar to Haines' jumps and stick-slip phenomena, with possible entrainment …

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Ccfss Technical Bulletin Spring 2006, Wei-Wen Yu Center For Cold-Formed Steel Structures Feb 2006

Ccfss Technical Bulletin Spring 2006, Wei-Wen Yu Center For Cold-Formed Steel Structures

CCFSS Technical Bulletins (1993 - 2020)

No abstract provided.

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Phase Distribution In An Upflow Monolith Reactor Using Computed Tomography, M. (Muthanna) H. Al-Dahhan, A. Kemoun, A. R. Cartolano Feb 2006

Phase Distribution In An Upflow Monolith Reactor Using Computed Tomography, M. (Muthanna) H. Al-Dahhan, A. Kemoun, A. R. Cartolano

Chemical and Biochemical Engineering Faculty Research & Creative Works

Computed Tomography (CT) is Known to Be a Viable Technique for Determining Flow Maldistribution in Two-Phase Flow through Packed Beds. in This Study, Gamma Ray Computed Tomography Has Been Used to Quantify the Flow Distribution in a Monolith Catalytic Bed, with Water as the Liquid Phase and Air as the Gas Phase, Flowing Co-Currently Upward. the Flow Conditions Were Selected to Bracket Some Commercially Viable Operating Conditions for Such Reactors. in the Monolith Core Region, Fairly Uniform Flow Distribution Has Been Obtained for All the Flow Conditions Used. This Distribution is Quantified using the Standard Deviation of the Holdup Distribution. …

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Supercritical-Carbon Dioxide-Assisted Cyclic Deposition Of Metal Oxide And Metal Thin Films, Dipak Barua, Theodosia Gougousi, Erin D. Young, Gregory N. Parsons Feb 2006

Supercritical-Carbon Dioxide-Assisted Cyclic Deposition Of Metal Oxide And Metal Thin Films, Dipak Barua, Theodosia Gougousi, Erin D. Young, Gregory N. Parsons

Chemical and Biochemical Engineering Faculty Research & Creative Works

Thin films of aluminum oxide and palladium were deposited on silicon at low temperatures (70-120 °C) by a cyclic adsorption/reaction processes using supercritical CO2 solvent. Precursors included Al(hfac)3, Al(acac)3, and Pd(hfac)2, and aqueous H2O2, tert-butyl peracetate, and H2 were used as the oxidants or reductants. For the precursors studied, growth proceeds through a multilayer precursor adsorption in each deposition cycle, and film thickness increased linearly with the number of growth cycles.

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Velocity Distribution Of Helium And Neon Atoms Released From Graphite And Tungsten Limiters In Textor, P. Lindner, M. Brix, Ph Mertens, A. Pospieszczyk, U. Samm, B. Schweer, B. Unterberg Feb 2006

Velocity Distribution Of Helium And Neon Atoms Released From Graphite And Tungsten Limiters In Textor, P. Lindner, M. Brix, Ph Mertens, A. Pospieszczyk, U. Samm, B. Schweer, B. Unterberg

Engineering Management and Systems Engineering Faculty Research & Creative Works

The release mechanisms of noble gases from plasma-facing components were observed spectroscopically in the TEXTOR plasma boundary by determining the velocity distribution from Doppler broadening. For the first time, three different mechanisms for helium and neon release from graphite and tungsten limiters could be distinguished quantitatively in a tokamak: thermal desorption, ion-induced desorption and particle reflection. Under the assumption that the thermal desorption follows a Maxwellian velocity distribution, the ion-induced desorption can be expressed by a Thompson velocity distribution. Calculating the particle reflection by the Monte-Carlo code TRIM, these processes could be separated in the measured velocity distribution. © 2005 …

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Ccfss News Spring 2006, Wei-Wen Yu Center For Cold-Formed Steel Structures Feb 2006

Ccfss News Spring 2006, Wei-Wen Yu Center For Cold-Formed Steel Structures

CCFSS Newsletters (1999 - 2008)

No abstract provided.

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Patterns In Team Communication During A Simulation Game, David M. Baca, Ray Luechtefeld, Steve Eugene Watkins Jan 2006

Patterns In Team Communication During A Simulation Game, David M. Baca, Ray Luechtefeld, Steve Eugene Watkins

Engineering Management and Systems Engineering Faculty Research & Creative Works

The development of communication skills is a necessary preparation for effective engineering teamwork. Argyris' "Theory of Action" provides a framework for understanding patterns in team dialogue. Students can benefit from an awareness of these patterns. The theory highlights the detection and correction of errors by sharing information during group collaboration and interactions. Quality decision-making can be enhanced when members of a team develop high degrees of openness and interdependence. Quality decision-making can be diminished when members of a team regulate the information shared within the team. This work analyzes team interactions from simulation games used in an interdisciplinary engineering course …

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Multiple Lebesgue Integration On Time Scales, Gusein Sh. Guseinov, Martin Bohner Jan 2006

Multiple Lebesgue Integration On Time Scales, Gusein Sh. Guseinov, Martin Bohner

Mathematics and Statistics Faculty Research & Creative Works

We study the process of multiple Lebesgue integration on time scales. The relationship of the Riemann and the Lebesgue multiple integrals is investigated.

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Creating Cross-Over Vehicles: Defining And Combining Vehicle Classes Using Shape Grammars, Seth D. Orsborn, R. Pawlicki, R. Smith, Jonathan Cagan Jan 2006

Creating Cross-Over Vehicles: Defining And Combining Vehicle Classes Using Shape Grammars, Seth D. Orsborn, R. Pawlicki, R. Smith, Jonathan Cagan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In the push for new vehicle designs, the distinctions between vehicle classes are quickly becoming blurred. We use shape grammars to quantify the differences between vehicle classes through the application of class-specific rules and the constraint of rule applications to within parametric ranges determined for each class. This allows for the development of new vehicle forms that clearly fall within a class or purposefully cross over the boundaries of classes and mix rules and ranges to create unique and interesting cross-over vehicles.

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Neuroadaptive Model Following Controller Design For A Nonaffine Uav Model, Nishant Unnikrishnan, S. N. Balakrishnan Jan 2006

Neuroadaptive Model Following Controller Design For A Nonaffine Uav Model, Nishant Unnikrishnan, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper proposes a new model-following adaptive control design technique for nonlinear systems that are nonaffine in control. The adaptive controller uses online neural networks that guarantee tracking in the presence of unmodeled dynamics and/or parameter uncertainties present in the system model through an online control adaptation procedure. The controller design is carried out in two steps: (i) synthesis of a set of neural networks which capture the unmodeled (neglected) dynamics or model uncertainties due to parametric variations and (ii) synthesis of a controller that drives the state of the actual plant to that of a reference model. This method …

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Mapping Ground Conditions Before The Development Of An Underground Hard Rock Mine - Mcarthur River Uranium Mine Case Study, Derek Apel, P. Szmigiel Jan 2006

Mapping Ground Conditions Before The Development Of An Underground Hard Rock Mine - Mcarthur River Uranium Mine Case Study, Derek Apel, P. Szmigiel

Mining Engineering Faculty Research & Creative Works

No abstract provided.

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Nanoparticles For Enhanced Delivery Of Chemotherapeutics, Emily J. Bahram-Ahi Jan 2006

Nanoparticles For Enhanced Delivery Of Chemotherapeutics, Emily J. Bahram-Ahi

Opportunities for Undergraduate Research Experience Program (OURE)

Delivery of the anticancer drug paclitaxel (commercially known as Taxol®) is difficult due to its limited solubility in aqueous media. This study proposes a novel bubble bursting technique to generate nanoparticles of the chemotherapeutic in an effort to decrease potential side effects and improve the bioavailability of hydrophobic drugs. The bubble bursting apparatus will be used to produce nanoparticles of a biodegradable polymer, poly(lactide-co-glycolide) (PLGA), as carriers for paclitaxel. The dissolved paclitaxel in this biodegradable polymer matrix will be released at a controlled rate for a more efficient delivery of the drug throughout the body.

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Galvanized Steel Framing For Residential Buildings, Nahb Research Center, Inc. Jan 2006

Galvanized Steel Framing For Residential Buildings, Nahb Research Center, Inc.

American Iron and Steel Institute (AISI) Specifications, Standards, Manuals and Research Reports (1946 - present)

No abstract provided.

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Regulation Of Powder Mass Flow Rate In Gravity-Fed Powder Feeder Systems, Vishnu Thayalan, Robert G. Landers Jan 2006

Regulation Of Powder Mass Flow Rate In Gravity-Fed Powder Feeder Systems, Vishnu Thayalan, Robert G. Landers

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Precise regulation of powder mass flow in laser-based manufacturing processes is critical to achieving excellent part dimensional and microstructure quality. Control of powder mass flow is challenging because low flow rates, where nonlinear effects are significant, are typically required. Also, gravity-fed powder feeder systems have significant material transport delays, making the control of powder mass flow even more challenging. This paper presents a control strategy for regulating the powder mass flow rate in a gravity-fed powder feeder system. A dynamic model of the powder feeder system, including material transport delay, is constructed, and a modified proportional plus integral (PI) controller …

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An Optimal Dynamic Inversion Approach For Controlling A Class Of One-Dimensional Nonlinear Distributed Parameter Systems, Radhakant Padhi, S. N. Balakrishnan Jan 2006

An Optimal Dynamic Inversion Approach For Controlling A Class Of One-Dimensional Nonlinear Distributed Parameter Systems, Radhakant Padhi, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Combining the principles of dynamic inversion and optimization theory, a new approach is presented for stable control of a class of one-dimensional nonlinear distributed parameter systems, assuming the availability a continuous actuator in the spatial domain. Unlike the existing approximate-then-design and design-then-approximate techniques, here there is no need of any approximation either of the system dynamics or of the resulting controller. Rather, the control synthesis approach is fairly straight-forward and simple. The controller formulation has more elegance because we can prove the convergence of the controller to its steady state value. To demonstrate the potential of the proposed technique, a …

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Electrostatic Active Radiation Shielding -- Revisited, John W. Wilson, R. K. Tripathi, R. C. Youngquist Jan 2006

Electrostatic Active Radiation Shielding -- Revisited, John W. Wilson, R. K. Tripathi, R. C. Youngquist

Mining Engineering Faculty Research & Creative Works

For the success of NASA's new vision for space exploration to Moon, Mars and beyond, exposures from the hazards of severe space radiation in deep space long duration missions is ''a must solve'' problem The payload penalty demands a very stringent requirement on the design of the spacecrafts for human deep space missions. Langley has developed state-of-the-art radiation protection and shielding technology for space missions. The exploration beyond low Earth orbit (LEO) to enable routine access to space require protection from the hazards of the accumulated exposures of space radiation, galactic cosmic rays (GCR) and solar particle events (SPE), and …

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Longitudinal Shock Wave Depolarization Of Pb(Zr₅₂Ti₄₈)O₃ Polycrystalline Ferroelectrics And Their Utilization In Explosive Pulsed Power, Sergey I. Shkuratov, Evgueni F. Talantsev, Jason Baird, Henryk Temkin, Larry L. Altgilbers, Allen H. Stults Jan 2006

Longitudinal Shock Wave Depolarization Of Pb(Zr₅₂Ti₄₈)O₃ Polycrystalline Ferroelectrics And Their Utilization In Explosive Pulsed Power, Sergey I. Shkuratov, Evgueni F. Talantsev, Jason Baird, Henryk Temkin, Larry L. Altgilbers, Allen H. Stults

Mining Engineering Faculty Research & Creative Works

A poled lead zirconate titanate Pb(Zr52Ti48)O3 (PZT) polycrystalline piezoelectric ceramic energy-carrying element of a compact explosive-driven power generator was subjected to a longitudinal explosive shock wave (the wave front traveled along the polarization vector P0). The shock compression of the element at pressures of 1.5-3.8 GPa caused almost complete depolarization of the sample. Shock wave velocity in the PZT was determined to be 3.94 ± 0.27 km/s. The electric charge stored in a ferroelectric, due to its remnant polarization, is released during a short time interval and can be transformed into pulsed power. Compact explosive-driven power sources utilizing longitudinal shock …

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Analysis Of Damage In Laminated Automotive Glazing Subjected To Simulated Head Impact, Shuangmei Zhao, Li Chai, S. D. Barbat, Lokeswarappa R. Dharani Jan 2006

Analysis Of Damage In Laminated Automotive Glazing Subjected To Simulated Head Impact, Shuangmei Zhao, Li Chai, S. D. Barbat, Lokeswarappa R. Dharani

Mechanical and Aerospace Engineering Faculty Research & Creative Works

During vehicle accidents, occupant's head impacting on windshield or side window is commonly observed. Any attempt to design glazing that minimizes injury to and death of occupants during a vehicle accident requires a thorough understanding of the mechanical behavior of automotive glazing subjected to head impact loads. A continuum damage mechanics (CDM) based constitutive model is developed and implemented into an axisymmetric finite element model to study the failure and impact resistance of laminated automotive glazing subjected to simulated head impact. An anisotropic elastic damage tensor with a linear damage evolution law is chosen to model the failure of the …

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Nonlinear Control Concepts For A Ua, Vijayakumar Janardhan, Derek Schmitz, S. N. Balakrishnan Jan 2006

Nonlinear Control Concepts For A Ua, Vijayakumar Janardhan, Derek Schmitz, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A reconfigurable flight control method is developed to be implemented on an Unmanned Aircraft (UA), a thirty percent scale model of the Cessna 150. This paper presents the details of the UA platform, system identification, reconfigurable controller design, development, and implementation on the UA to analyze the performance metrics. A Crossbow Inertial Measurement Unit provides the roll, pitch, and yaw accelerations and rates along with the roll and pitch. The 100-400 mini-air data boom from SpaceAge Control provides the airspeed, altitude, angle of attack, and the side slip angles. System identification is accomplished by commanding preprogrammed inputs to the control …

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Optimal Impulse Control Of Systems With Control Constraints And Application To Hiv Treatment, Vivek Yadav, S. N. Balakrishnan Jan 2006

Optimal Impulse Control Of Systems With Control Constraints And Application To Hiv Treatment, Vivek Yadav, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In this paper, conditions for optimal impulse control of an impulsive system with constraints on control are derived. These hold for a system whose states can be changed instantaneously at discrete times with impulses while a continuous control is being applied between those times. The conditions derived are applied to the problem of optimal HIV treatment. Simulation results are presented to show the treatment procedure. The results obtained show that the intervention method developed leads to good results.

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Mobile Speed Classification For Cellular Systems Over Frequency Selective Rician Fading Channels, Y. Rosa Zheng, Chengshan Xiao Jan 2006

Mobile Speed Classification For Cellular Systems Over Frequency Selective Rician Fading Channels, Y. Rosa Zheng, Chengshan Xiao

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, a new algorithm is proposed for estimating mobile speed of cellular systems over frequency selective Rician fading channels. Theoretical analysis is first derived and practical algorithm is proposed based on the analytical results. The algorithm employs a modified auto-covariance of received signal power to estimate the speed of mobiles. The algorithm is based on the received signals which contain unknown transmitted data, unknown frequency selective multipaths including line-of-sight(LOS) component, and random receiver noise. The algorithm works very well for frequency selective Rician fading channels with large ranges of Rice factor and angle of arrival of the LOS …

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Circuit Models For Power Bus Structures On Printed Circuit Boards Using A Hybrid Fem-Spice Method, Todd H. Hubing, Chunlei Guo Jan 2006

Circuit Models For Power Bus Structures On Printed Circuit Boards Using A Hybrid Fem-Spice Method, Todd H. Hubing, Chunlei Guo

Electrical and Computer Engineering Faculty Research & Creative Works

Power bus structures consisting of two parallel conducting planes are widely used on high-speed printed circuit boards. In this paper, a full-wave finite-element method (FEM) method is used to analyze power bus structures, and the resulting matrix equations are converted to equivalent circuits that can be analyzed using SPICE programs. Using this method of combining FEM and SPICE, power bus structures of arbitrary shape can be modeled efficiently both in the time-domain and frequency-domain, along with the circuit components connected to the bus. Dielectric loss and losses due to the finite resistance of the power planes can also be modeled. …

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Hdp Based Optimal Control Of A Grid Independent Pv System, Richard L. Welch, Ganesh K. Venayagamoorthy Jan 2006

Hdp Based Optimal Control Of A Grid Independent Pv System, Richard L. Welch, Ganesh K. Venayagamoorthy

Electrical and Computer Engineering Faculty Research & Creative Works

This paper presents an adaptive optimal control scheme for a grid independent photovoltaic (PV) system consisting of a PV collector array, a storage battery, and loads (critical and non-critical loads). The optimal control algorithm is based on the model-free heuristic dynamic programming (HDP), an adaptive critic design (ACD) technique which optimizes the control performance based on a utility function. The HDP critic network is used in a PV system simulation study to train a neurocontroller to provide optimal control for varying PV system output energy and load demands. The emphasis of the optimal controller is primarily to supply the critical …

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Optimal Design Of Power System Stabilizers Using A Small Population Based Pso, Ganesh K. Venayagamoorthy, Tridib Kumar Das Jan 2006

Optimal Design Of Power System Stabilizers Using A Small Population Based Pso, Ganesh K. Venayagamoorthy, Tridib Kumar Das

Electrical and Computer Engineering Faculty Research & Creative Works

Power system stabilizers (PSSs) are used to generate supplementary control signals to excitation systems in order to damp out local and inter-area oscillations. In this paper, a modified particle swarm optimization (PSO) algorithm with a small population is presented for the design of optimal PSSs. The small population based PSO (SPPSO) is used to determine the optimal parameters of several PSSs simultaneously in a multi-machine power system. In order to maintain a dynamic search process, the idea of particle regeneration in the population is also proposed. Optimal PSS parameters are determined for the power system subjected to small and large …

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Experimental Simulation Of Lightning Optical Emissions In Clouds, Anil Ogale, Kunal Mitra, Arindam Banerjee Jan 2006

Experimental Simulation Of Lightning Optical Emissions In Clouds, Anil Ogale, Kunal Mitra, Arindam Banerjee

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The objective of the study is to experimentally determine the information content of lightning optical emissions through clouds. Clouds affect the amplitude of lightning signals and the apparent dimensions of the optical source. Multiple scattering from the cloud media also alters the shape of the temporal profile of the lightning signal. The goal is to provide accurate estimates of the arrival time delay and temporal pulse width broadening of output signals emitted from clouds for different cloud and lightning parameters. Experiments conducted in the laboratory yield a temporally broadened pulse with an overall decrease in the peak and a delay …

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Magnetically Filtered Faraday Probe For Measuring The Ion Current Density Profile Of A Hall Thruster., Joshua L. Rovey, Mitchell L. R. Walker, Alec D. Gallimore, Peter Y. Peterson Jan 2006

Magnetically Filtered Faraday Probe For Measuring The Ion Current Density Profile Of A Hall Thruster., Joshua L. Rovey, Mitchell L. R. Walker, Alec D. Gallimore, Peter Y. Peterson

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The ability of a magnetically filtered Faraday probe (MFFP) to obtain the ion current density profile of a Hall thruster is investigated. The MFFP is designed to eliminate the collection of low-energy, charge-exchange (CEX) ions by using a variable magnetic field as an ion filter. In this study, a MFFP, Faraday probe with a reduced acceptance angle (BFP), and nude Faraday probe are used to measure the ion current density profile of a 5 kW Hall thruster operating over the range of 300-500 V and 5-10 mg/s. The probes are evaluated on a xenon propellant Hall thruster in the University …

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System For Heating Bulk Materials, Nassib Aouad, J. Kennedy Jan 2006

System For Heating Bulk Materials, Nassib Aouad, J. Kennedy

Mining Engineering Faculty Research & Creative Works

A system for heating bulk material to remove moisture. The system includes a heat exchanger system in the floor of a bin for receiving moist bulk material. The heat exchanger system is capable of withstanding the weight of the bulk material as well as being stable for the dynamic process of loading and discharging the bulk material. The heat exchanger includes a plurality of spaced beams mounted between a top plate and bottom plate. The spaced beams form conduits for receiving water or other fluids that have been heated by a stove capable of burning wood, coal, biomass material or …

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A Closed-Form Expression For Estimating Radiated Emissions From The Power Planes In A Populated Printed Circuit Board, Todd H. Hubing, Hwan-Woo Shim Jan 2006

A Closed-Form Expression For Estimating Radiated Emissions From The Power Planes In A Populated Printed Circuit Board, Todd H. Hubing, Hwan-Woo Shim

Electrical and Computer Engineering Faculty Research & Creative Works

An expression for the maximum intensity of radiated emissions from a rectangular power bus structure has been derived based on an analytical cavity-resonator model. The effect of components mounted on the board is modeled by modifying the propagation constant of the waves within the power bus structure. The radiated field intensity is calculated using the equivalent magnetic current around the edges of the power bus structure together with the modified propagation constant. Measurements of a populated test board show that the derived closed-form expression estimates the level of the maximum radiation intensity with reasonable accuracy.

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