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Missouri University of Science and Technology

2006

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Articles 391 - 411 of 411

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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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Neural Network Control Of Spark Ignition Engines With High Egr Levels, A. Singh, Brian C. Kaul, J. A. Drallmeier, Jagannathan Sarangapani, Jonathan B. Vance Jan 2006

Neural Network Control Of Spark Ignition Engines With High Egr Levels, A. Singh, Brian C. Kaul, J. A. Drallmeier, Jagannathan Sarangapani, Jonathan B. Vance

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Research has shown substantial reductions in the oxides of nitrogen (NOx) concentrations by using 10% to 25% exhaust gas recirculation (EGR) in spark ignition (SI) engines [1]. However under high EGR levels the engine exhibits strong cyclic dispersion in heat release which may lead to instability and unsatisfactory performance. A suite of neural network (NN)-based output feedback controllers with and without reinforcement learning is developed to control the SI engine at high levels of EGR even when the engine dynamics are unknown by using fuel as the control input. A separate control loop was designed for controlling EGR levels. The …

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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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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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Robust/Optimal Temperature Profile Control Using Neural Networks, Vivek Yadav, Radhakant Padhi, S. N. Balakrishnan Jan 2006

Robust/Optimal Temperature Profile Control Using Neural Networks, Vivek Yadav, Radhakant Padhi, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

An approximate dynamic programming (ADP) based neurocontroller is developed for a heat transfer application. Heat transfer problem for a fin in a car''s electronic module is modeled as a nonlinear distributed parameter (infinite-dimensional) system by taking into account heat loss and generation due to conduction, convection and radiation. A low-order, finite-dimensional lumped parameter model for this problem is obtained by using Galerkin projection and basis functions designed through the `Proper Orthogonal Decomposition'' technique (POD) and the `snap-shot'' solutions. A suboptimal neurocontroller is obtained with a single-network-adaptivecritic (SNAC). Further contribution of this paper is to develop an online robust controller to …

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Optimal Management Of Beaver Population Using A Reduced-Order Distributed Parameter Model And Single Network Adaptive Critics, Radhakant Padhi, S. N. Balakrishnan Jan 2006

Optimal Management Of Beaver Population Using A Reduced-Order Distributed Parameter Model And Single Network Adaptive Critics, Radhakant Padhi, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Beavers are often found to be in conflict with human interests by creating nuisances like building dams on flowing water (leading to flooding), blocking irrigation canals, cutting down timbers, etc. At the same time they contribute to raising water tables, increased vegetation, etc. Consequently, maintaining an optimal beaver population is beneficial. Because of their diffusion externality (due to migratory nature), strategies based on lumped parameter models are often ineffective. Using a distributed parameter model for beaver population that accounts for their spatial and temporal behavior, an optimal control (trapping) strategy is presented in this paper that leads to a desired …

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Permutation Coding Technique For Image Recognition Systems, Ernst M. Kussul, Tatiana N. Baidyk, Donald C. Wunsch, Oleksandr Makeyev, Anabel Martin Jan 2006

Permutation Coding Technique For Image Recognition Systems, Ernst M. Kussul, Tatiana N. Baidyk, Donald C. Wunsch, Oleksandr Makeyev, Anabel Martin

Electrical and Computer Engineering Faculty Research & Creative Works

A feature extractor and neural classifier for image recognition systems are proposed. The proposed feature extractor is based on the concept of random local descriptors (RLDs). It is followed by the encoder that is based on the permutation coding technique that allows to take into account not only detected features but also the position of each feature on the image and to make the recognition process invariant to small displacements. The combination of RLDs and permutation coding permits us to obtain a sufficiently general description of the image to be recognized. The code generated by the encoder is used as …

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Crystal And Electronic Structures Of Linh₂, Jinbo Yang, X.-D. Zhou, Qingsheng Cai, William Joseph James, William B. Yelon Jan 2006

Crystal And Electronic Structures Of Linh₂, Jinbo Yang, X.-D. Zhou, Qingsheng Cai, William Joseph James, William B. Yelon

Materials Science and Engineering Faculty Research & Creative Works

The crystal structure of LiNH2 was reinvestigated using powder neutron diffraction with high sensitivity. The compound crystallizes in the tetragonal space group I4 with lattice parameters α = b= 5.034 42 (24) Å, c = 10.255 58 (52) Å. It is found that H atoms occupy 8g1(0.2429, 0.1285, 0.1910) and 8g2 (0.3840, 0.3512, 0.1278) sites. The bond lengths between the nearest nitrogen and hydrogen atoms are 0.986 and 0.942 Å, respectively. The bond angle between H-N-H is about 99.97°. These results are significantly different from those of previous experiments. The electronic structure was calculated according to the revised structural …

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Novel Sum-Of-Sinusoids Simulation Models For Rayleigh And Rician Fading Channels, Chengshan Xiao, Y. Rosa Zheng, N. C. Beaulieu Jan 2006

Novel Sum-Of-Sinusoids Simulation Models For Rayleigh And Rician Fading Channels, Chengshan Xiao, Y. Rosa Zheng, N. C. Beaulieu

Electrical and Computer Engineering Faculty Research & Creative Works

The statistical properties of Clarke's fading model with a finite number of sinusoids are analyzed, and an improved reference model is proposed for the simulation of Rayleigh fading channels. A novel statistical simulation model for Rician fading channels is examined. The new Rician fading simulation model employs a zero-mean stochastic sinusoid as the specular (line-of-sight) component, in contrast to existing Rician fading simulators that utilize a non-zero deterministic specular component. The statistical properties of the proposed Rician fading simulation model are analyzed in detail. It is shown that the probability density function of the Rician fading phase is not only …

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On Discrete-Time Modeling Of Time-Varying Wssus Fading Channels, Christian Sgraja, Chengshan Xiao Jan 2006

On Discrete-Time Modeling Of Time-Varying Wssus Fading Channels, Christian Sgraja, Chengshan Xiao

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, we consider the serial concatenation of linear time-varying (LTV) systems and its impact on the discrete-time modeling of wide-sense stationary uncorrelated scattering (WSSUS) fading channels. By deriving an expression for the composite impulse response of the overall concatenated system, we find that unlike the time-invariant case, the concatenation of LTV systems is not commutative, i. e., the order of arrangement affects the overall impulse response. This has significant impact when a digital transmission over a time-varying fading channel, which is an LTV channel, is represented by an equivalent discrete-time model that incorporates both transmitter and receiver filters. …

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Operational Characteristics Of Wind Plants And Windfarms, Badrul H. Chowdhury Jan 2006

Operational Characteristics Of Wind Plants And Windfarms, Badrul H. Chowdhury

Electrical and Computer Engineering Faculty Research & Creative Works

A wide range of power generation technologies exist today, whose characteristics can vary significantly. Additionally, a diverse range of wind turbines are available in the market. With experienced wind developers taking the charge in installing multi-megawatt-size windfarms at a rapid pace, the role of wind power in electricity generation is bound to grow in significance in the coming years. This panel takes a critical look at the operating characteristics of existing and planned wind power generation systems and their relationship to interconnection requirements and performance standards.

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Power System Control With An Embedded Neural Network In Hybrid System Modeling, Seung-Mook Baek, Jung-Wook Park, Ganesh K. Venayagamoorthy Jan 2006

Power System Control With An Embedded Neural Network In Hybrid System Modeling, Seung-Mook Baek, Jung-Wook Park, Ganesh K. Venayagamoorthy

Electrical and Computer Engineering Faculty Research & Creative Works

The output limits of the power system stabilizer (PSS) can improve the system damping performance immediately following a large disturbance. Due to non-smooth nonlinearities from the saturation limits, these values cannot be determined by the conventional tuning methods based on linear analysis. Only ad hoc tuning procedures can been used. A feedforward neural network (FFNN) (with a structure of multilayer perceptron neural network) is applied to identify the dynamics of an objective function formed by the states, and thereafter to compute the gradients required in the nonlinear parameter optimization. Moreover, its derivative information is used to replace that obtained from …

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Completely Explosive Autonomous High-Voltage Pulsed-Power System Based On Shockwave Ferromagnetic Primary Power Source And Spiral Vector Inversion Generator, Sergey I. Shkuratov, Evgueni F. Talantsev, Jason Baird, Millard F. Rose, Zachary Shotts, Z. Roberts, Allen H. Stults, Larry L. Altgilbers Jan 2006

Completely Explosive Autonomous High-Voltage Pulsed-Power System Based On Shockwave Ferromagnetic Primary Power Source And Spiral Vector Inversion Generator, Sergey I. Shkuratov, Evgueni F. Talantsev, Jason Baird, Millard F. Rose, Zachary Shotts, Z. Roberts, Allen H. Stults, Larry L. Altgilbers

Mining Engineering Faculty Research & Creative Works

Novel explosive and conventional pulsed-power technologies were combined, and a series of explosive-driven high-voltage power supplies was designed, built, and tested. The power supply contained an explosive-driven high-voltage primary power source based on the fundamental physical effect of shockwave demagnetization of Nd2 Fe14B high-energy ferromagnet and a power-conditioning stage. The volume of the energy-carrying ferromagnetic elements in the shockwave ferromagnetic generators (FMGs) was 8.75 cm3. The power-conditioning stage was based on the spiral vector inversion generator (VIG). The combined FMG-VIG system demonstrated successful operation and good performance. The output-voltage pulse amplitude of the combined FMG-VIG …

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Pulse Charging Of Capacitor Bank By Explosive-Driven Shock Wave Ferroelectric Generator, Sergey I. Shkuratov, Evgueni F. Talantsev, Jason Baird, Allen H. Stults, Larry L. Altgilbers Jan 2006

Pulse Charging Of Capacitor Bank By Explosive-Driven Shock Wave Ferroelectric Generator, Sergey I. Shkuratov, Evgueni F. Talantsev, Jason Baird, Allen H. Stults, Larry L. Altgilbers

Mining Engineering Faculty Research & Creative Works

Ultracompact explosive-driven shock wave ferroelectric generators (FEGs) were used as autonomous primary power sources for charging capacitor banks of different capacitance. The FEGs utilized longitudinal (when the shock wave propagates along the polarization vector P) shock wave depolarization of Pb(Zr52Ti48)O3 (PZT) polycrystalline ferroelectric ceramic. PZT disks having diameters ranging from 25 to 27 mm and three different thicknesses: 0.65, 2.1, and 5.1 mm. It was experimentally shown that during the charging process the FEGs were capable of producing pulsed power with peak amplitudes up to 0.3 MW. Results for charging voltage, electric charge transfer and …

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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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Completely Explosive Ultracompact High-Voltage Nanosecond Pulse-Generating System, Sergey I. Shkuratov, Evgueni F. Talantsev, Jason Baird, Millard F. Rose, Zachary Shotts, Larry L. Altgilbers, Allen H. Stults Jan 2006

Completely Explosive Ultracompact High-Voltage Nanosecond Pulse-Generating System, Sergey I. Shkuratov, Evgueni F. Talantsev, Jason Baird, Millard F. Rose, Zachary Shotts, Larry L. Altgilbers, Allen H. Stults

Mining Engineering Faculty Research & Creative Works

A conventional pulsed power technology has been combined with an explosive pulsed power technology to produce an autonomous high-voltage power supply. The power supply contained an explosive-driven high-voltage primary power source and a power-conditioning stage. The ultracompact explosive-driven primary power source was based on the physical effect of shock-wave depolarization of high-energy Pb(Zr52Ti48)O3 ferroelectric material. The volume of the energy-carrying ferroelectric elements in the shock-wave ferroelectric generators (SWFEGs) varied from 1.2 to 2.6 cm3. The power-conditioning stage was based on the spiral vector inversion generator (VIG). The SWFEG-VIG system demonstrated successful operation and good performance. The amplitude of the output …

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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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Neural Network-Based Output Feedback Controller For Lean Operation Of Spark Ignition Engines, Brian C. Kaul, Jagannathan Sarangapani, J. A. Drallmeier, Jonathan B. Vance, Pingan He Jan 2006

Neural Network-Based Output Feedback Controller For Lean Operation Of Spark Ignition Engines, Brian C. Kaul, Jagannathan Sarangapani, J. A. Drallmeier, Jonathan B. Vance, Pingan He

Electrical and Computer Engineering Faculty Research & Creative Works

Spark ignition (SI) engines running at very lean conditions demonstrate significant nonlinear behavior by exhibiting cycle-to-cycle dispersion of heat release even though such operation can significantly reduce NOx emissions and improve fuel efficiency by as much as 5-10%. A suite of neural network (NN) controller without and with reinforcement learning employing output feedback has shown ability to reduce the nonlinear cyclic dispersion observed under lean operating conditions. The neural network controllers consists of three NN: a) A NN observer to estimate the states of the engine such as total fuel and air; b) a second NN for generating virtual input; …

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Neuro Control Of Nonlinear Discrete Time Systems With Deadzone And Input Constraints, Pingan He, Wenzhi Gao, Jagannathan Sarangapani Jan 2006

Neuro Control Of Nonlinear Discrete Time Systems With Deadzone And Input Constraints, Pingan He, Wenzhi Gao, Jagannathan Sarangapani

Electrical and Computer Engineering Faculty Research & Creative Works

A neural network (NN) controller in discrete time is designed to deliver a desired tracking performance for a class of uncertain nonlinear systems with unknown deadzones and magnitude constraints on the input. The NN controller consists of two NNs: the first NN for compensating the unknown deadzones; and the second NN for compensating the uncertain nonlinear system dynamics. The magnitude constraints on the input are modeled as saturation nonlinearities and they are dealt with in the Lyapunov-based controller design. The uniformly ultimate boundedness (UUB) of the closed-loop tracking errors and the neural network weights estimation errors is demonstrated via Lyapunov …

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The Antecedents Of M-Commerce Adoption, Morris Kalliny, Michael S. Minor Jan 2006

The Antecedents Of M-Commerce Adoption, Morris Kalliny, Michael S. Minor

Business and Information Technology Faculty Research & Creative Works

The growth of Internet shopping has been attributed to rapid advances in technology and other influences such as convenience. We empirically investigate the relationship between demographics, ease of use, convenience, usefulness and enjoyment and intention to use m-commerce and attitude toward m-commerce. Two studies were conducted where a student and a non student sample was used. Data analysis revealed age, gender and educational level of customers do not play a role in influencing intention to use m-commerce. However, convenience, ease of use, usefulness and enjoyment all play a role in the customer's intention to use m-commerce.

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Use Of A Classroom Response System To Enhance Classroom Interactivity, Keng Siau, Hong Sheng, Fiona Fui-Hoon Nah Jan 2006

Use Of A Classroom Response System To Enhance Classroom Interactivity, Keng Siau, Hong Sheng, Fiona Fui-Hoon Nah

Business and Information Technology Faculty Research & Creative Works

Classroom interactivity is a critical component of teaching and learning. This paper reports on the use of a classroom response system to enhance classroom interactivity in a systems analysis and design course. The success of the project was assessed using both quantitative and qualitative data. A pretest/posttest design was used to examine the effects of a classroom response system on interactivity. The results show that a classroom response system can significantly improve classroom interactivity. Qualitative data was also collected to identify the strengths and weaknesses of using a classroom response system to enhance classroom interaction. Based on the quantitative and …

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