bluuebunny/crossref_metadata_2025 huggingface dataset:
Integration of Heat Conduction Measurement Systems Into Engineering Technology Education
Authors: Eberth John F. , Porter Jay , Marotta Egidio E. , Fletcher Leroy S.
Published: April 2008

Modern engineering technology education necessitates realistic, cross disciplinary research projects. Maintaining these research opportunities within the university is an effective way for undergraduate students to practice their profession while assisting with graduate level research. In the heat conduction laboratory, the Mechanical Engineering Department at Texas A&M has joined with the Department of Engineering Technology and Industrial Distribution to create a novel learning environment beneficial to both students and professors. The goal of this project is to design and implement an improved thermal test chamber using mechatronic concepts. Similarly, the educational goal is to have engineering technology students apply their classroom based learning to a real-world application and to coordinate their efforts with a diverse background of advisors and engineers.
A Magnetorheological Vibration Isolator for Hydraulic Hybrid Vehicles
Authors: Nguyen The M. , Elahinia Mohammad H.
Published: April 2008

This paper presents the results of vibration isolation analysis for the pump/motor component of hydraulic hybrid vehicles (HHV). The hybrid subsystem can potentially improve the fuel efficiency of the vehicle by recovering some of the energy that is otherwise wasted in friction brakes. High pressure hydraulic fluid “assists” the engine in the initial acceleration period. Noise and vibration are an issue with these systems due to the variable hydraulic loads that are applied to the regenerative hybrid element. This study looks into the possibility of reducing the transmitted noise and vibration to the vehicle’s chassis by using smart magnetorheological (MR) dampers. MR dampers utilize MR fluid which is made of pure iron particles suspended in a carrier fluid. MR fluids deliver variable yield stress under the effect of a controllable electromagnetic field. To this end, an MR damper is modeled and simulated. In the simulation both shock and vibration loads are considered. The simulation results are compared with the performance of regular elastomer isolators. It is shown that the MR damper can effectively reduce the vibration for different working cycles of the regenerative system.
Quantification and Use of System Coupling in Decomposed Design Optimization Problems
Authors: Alyaqout Sulaiman F. , Papalambros Panos Y. , Ulsoy A. Galip
Published: April 2008

Decomposition-based optimization strategies are used to solve complex engineering design problems that might be otherwise unsolvable. Yet, the associated computational cost can be prohibitively high due to the often large number of separate optimizations needed for coordination of problem solutions. To reduce this cost one may exploit the fact that some systems may be weakly coupled and their interactions can be suspended with little loss in solution accuracy. Suspending such interactions is usually based on the analyst’s experience or experimental observation. This article introduces an explicit measure of coupling strength among interconnected subproblems in a decomposed optimization problem, along with a systematic way for calculating it. The strength measure is then used to suspend weak couplings and thus improve system solution strategies, such as the model coordination method. Examples show that the resulting strategy can decrease the number of required system optimizations significantly.
Experimental Investigation for Chemo-Mechanical Actuation Using Biological Transport Mechanisms
Authors: Sundaresan Vishnu Baba , Leo Donald J.
Published: April 2008

Plants have the ability to develop large mechanical force from chemical energy available with bio-fuels. The energy released by the cleavage of a terminal phosphate ion during the hydrolysis of bio-fuel assists the transport of ions and fluids in cellular homeostasis. Materials that develop pressure and hence strain similar to the response of plants to an external stimuli are classified as nastic materials. Calculations for controlled actuation of an active material inspired by biological transport mechanism demonstrated the feasibility of developing such a material with actuation energy densities on the order of 100kJ/m3 by Sundaresan et. al [2004]. The mathematical model for a simplified proof of concept actuator referred to as micro hydraulic actuator uses ion transporters extracted from plants reconstituted on a synthetic bilayer lipid membrane (BLM). Thermodynamic model of the concept actuator discussed in Sundaresan et. al [2005] predicted the ability to develop 5% normalized deformation in thickness of the micro-hydraulic actuator. Our experimental demonstration of controlled fluid transport through AtSUT4 reconstituted on a 1-Palmitoyl-2-Oleoyl-sn-Glycero-3-[Phospho-L-Serine] (Sodium Salt) (POPS), 1-Palmitoyl-2-Oleoyl-sn-Glycero-3-Phosphoethanolamine (POPE) BLM on lead silicate glass plate having an array of 50 μm holes driven by proton gradient is discussed here.
Energy Transfer and Dissipation in a Three-Degree-of-Freedom System With Stribeck Friction
Authors: Do Nguyen , Ferri Aldo A.
Published: April 2008

Friction at connecting joints is a key mechanism by which passive damping occurs in built-up structures. This paper explores the ability of friction to transfer energy between subsystems of an interconnected system. Two single-degree-of-freedom (SDOF) systems are used to represent separate subsystems and a third mass is used to represent the connecting joint. A Stribeck friction model is used to represent the resistive force acting on this coupling mass. Through numerical simulation studies, the influence of the subsystem dynamics on the overall energy dissipation levels is investigated. In particular, it is seen that favorable tuning conditions exist that result in a “pumping” of energy from the low-frequency motion of one subsystem to the higher-frequency motion of the other subsystem. It is also seen that one-way energy transfer can occur in such a system due to the eventual joint lock-up that can occur when the connecting mass sticks.
Software Enabled Variable Displacement Pumps
Authors: Li Perry Y. , Li Cassie Y. , Chase Thomas R.
Published: April 2008

Direct pump control of hydraulic systems is more energy efficient than throttle valve based methods to control hydraulic systems. This requires variable displacement pumps that are responsive and capable of electronic control. Such Electronic Displacement Controlled (EDC) pumps tend to be significantly larger, heavier and more expensive than fixed displacement counterparts. In addition, achievable control bandwidths are typically lower than throttle valve based control approaches. We have recently begun a project to achieve the functionality of a variable displacement pump by combining a fixed displacement pump, a pulse width modulated (PWM) on/off valve under closed loop feedback control, and an accumulator. The proposed topology is the hydro-mechanical analog of the DC-DC boost converter in power electronics. Since on/off valves have little loss in either the on or the off state, this approach is potentially more efficient than throttle valve based control approaches. It has the small size/weight and low cost advantages of a fixed displacement pump. Faster response can be expected by eliminating the intervening inertias of the swash plate control system. The pump’s functionalities can also be easily programmed by controlling the PWM on/off valve in different manners. This paper presents some preliminary results from this ongoing research program. While the PWM valve based approach provides desirable features, it also introduces undesirable ripples to the system pressure and flow rate. It is shown that increasing the accumulator pre-charge pressure and the accumulator volume can decrease ripple size at the expense of response time. This apparent trade-off can be alleviated by feedback control to achieve fast response time while keeping ripple small. Feedback control using PWM control must be implemented with care since the conventional “state-space” model may not be valid when the PWM frequency is low. On the other hand, increasing PWM frequency reduces ripple size and enables the system to achieve high control bandwidths.
Reduction of Vortex-Driven Oscillations in a Choked Duct Through Active Control
Authors: Ward Jami W. , Leonessa Alexander , Petersen Eric L.
Published: April 2008

The effectiveness of active control schemes for the reduction of vortex-driven instabilities is demonstrated using an experimental setup consisting of a non-reacting primary flow of air, where both the duct exit and inlet are choked. Two plates produce the vortex-shedding phenomenon at the duct’s first longitudinal mode. The potentially damaging low-frequency instabilities that arise when vortex-shedding frequencies couple with the natural acoustic modes of a choked duct are controlled using a secondary injection method, consisting of pulsing compressed air. A dynamic pressure transducer placed near the chamber exit allows to feed back the information needed to implement a closed-loop control scheme which effectively modifies the phasing of the secondary flow. The proposed approach was proven to be an effective means of reducing the problematic instabilities providing a 66% reduction in the FFT RMS amplitude when utilizing a Proportional-Derivative controller.
Manufacture of Microcantilever Sensors
Authors: McFarland Andrew W. , Colton Jonathan S. , Cox Daniel , Liang Steven Y.
Published: April 2008

Mechanical micro machining is an emerging technology with many potential benefits and equally great challenges. The push to develop processes and tools capable of micro scale fabrication is a result of the widespread drive to reduce part and feature size. One important factor that contributes to the ability to machine at the microscale level is the overall size of the machine tool due to the effects of thermal, static, and dynamic stabilities. This paper explores the technical feasibility of miniaturized machine tools capable of fabricating features and parts on the micro scale in terms of depth of cut and part form accuracy. It develops a machine tool and examines its capabilities through benchmarking tests and the making of precision dies for the injection molding of microcantilever parts. The design and configuration of a miniaturized vertical machining center of overall dimension less than 300 mm on a side is presented and the component specifications discussed. The six axis machine has linear positioning resolution of 4 nm by 10 nm by 10 nm, with accuracy on the order of 0.3 μm, in the height, feed, and cross feed directions. The work volume as defined by the ranges of axes travel are 4 mm by 25 mm by 25 mm in the height, feed, and cross feed and 20 degrees in the rotational space. To quantify the performance capability of the miniaturized machine tool as a system, a series of evaluation tests were implemented based on linear and arch trajectories over a range of feed speed and depth of cut conditions. Test results suggest that micro level form accuracy and sub-micron level finish are generally achievable for parts with moderate curvature and gradient in the geometry under selected machining parameters and conditions. An injection mold was made of steel with this machine and plastic microcantilevers fabricated. Plastic microcantilevers are appropriate for sensing applications such as surface probe microscopy. The microcantilevers, made from polystyrene, were 464 to 755 μm long, 130 μm wide and only 6–9 μm thick. They showed very good uniformity, reproducibility, and appropriate mechanical response for use as sensors in surface force microscopy.
A Comparison of H-Infinity With Kalman Filtering in Parameter Identification
Authors: Kiriakidis Kiriakos , O’Brien Richard T.
Published: April 2008

The authors perform a thorough investigation of the extended H-infinity and Kalman filters based on results from stiffness estimation experiments. The paper uses the time-varying tolerance method to tune the H-infinity filter. Exploring similarities in the associated Riccati equations, the authors also propose a new approach for tuning the Kalman filter. The experimental results show that the H-infinity outperforms the Kalman filter along a wide range of tuning parameter values.
Numerical Modeling of Dissociation-Injection Process for the Electrohydrodynamic Pumping
Authors: Shooshtari A. , Chowdhury S. , Ohadi M.
Published: April 2008

In recent decades, the phenomenon of electrohydrodynamics (EHD) has gained prominence due to its potential applications in microsystems. One such application is pumping and transport of dielectric fluids in micropumps meant for cooling or other such purposes. Electrohydrodynamics can be defined as a direct coupling between the electric and hydrodynamic fields, where the electric field produces fluid motion. The motion of the fluid can occur due to an electrical body force being exerted on the fluid. In single-phase liquid flows, the electrophoretic (Coulombic) component of the electrical body force is the main driving force that acts on the free charge carriers. There are different physico-chemical processes that result in production of free charge carriers inside fluids; among these processes, the ion-injection and conduction/dissociation of ionic pairs are typical and hence worth mentioning. So far, several different numerical methods have been developed to model the EHD pumping effect due to the ion-injection process and the process of dissociation of ionic pairs. This paper presents a numerical model of the electrophoretic force in dielectric liquids that combines both the aspects of dissociation of ionic pairs and ion-injection processes. In this modeling, it is assumed that the ion injection process is unipolar. However, the dissociation process generates both positive and negative ions. Therefore, modeling of this process involves determining the concentration of both types of ions. The present modeling procedure is used to simulate a mesoscale electrohydrodynamic pump where the numerical and experimental results are compared and found to be in agreement within acceptable limits. This modeling technique serves as an effective tool for prediction and optimization of the electrohydrodynamic pumps.
Dynamic Testing of Mechanical Properties of a Substrate Using Phase-Locked-Loop
Authors: Clark Matthew , Feng Z. C.
Published: April 2008

This paper explores dynamically deriving the mechanical properties of a substrate. A method is presented in which a phase locked loop (PLL) is used to find the resonance frequency of a mechanical model consisting of an oscillating probe and a material substrate. This is done by first presenting an accurate PLL which is stable for nonlinear systems. The relationship between the system frequency and the stiffness of the material substrate is derived theoretically. The stiffness of the substrate is obtained by combining the theoretical result and the converging resonance frequency from PLL.
Servo Control and Energetic Characterization of a Proportionally Injected Liquid-Fueled Actuator for Power-Autonomous Mobile Robots
Authors: Fite Kevin B. , Goldfarb Michael
Published: April 2008

This paper describes and characterizes a chemo-mechanical actuator that incorporates proportionally controlled injection valves for the direct injection of a hot-gas actuator. Proportional control of the liquid propellant provides for high-resolution control without sacrificing the maximum output power of the valves. The design of the proportional injection valves will be briefly discussed, along with the design of the actuator force controller. Experimental results of the force and position tracking of the actuator are presented. Finally, an energetic characterization of the actuator shows improvement relative to prior configurations, and shows marked improvement relative to state-of-the-art batteries and motors.
Improved Haptic Two-Port Networks Through Force Feedback and Admittance/Impedance Network Duality
Authors: Tognetti Lawrence J. , Book Wayne J.
Published: April 2008

This paper uses the two–port network with virtual coupling paradigm to analyze various haptic system architectures. Haptic Two–Port Network (H2PN) numerical tuning algorithms and analysis techniques based on Llewelyn Stability Criterion are presented and lay the groundwork for testing haptic networks on HuRBiRT (Human Robotic Bilateral Research Tool), a large scale nonlinear hybrid active / passive haptic device. This paper presents the addition of local force feedback to the Impedance / Admittance (I/A) H2PN to form the true dual of the Admittance / Impedance (A/I) H2PN and explores alternative impedance and admittance virtual coupling forms. First, I/A and A/I H2PN’s are numerically tuned using a linearized dynamic model of HuRBiRT and resulting admittance and impedance limits of the respective networks are compared to add insight on the duality of the two different implementations of haptic causality, with specific consideration given to the advantage of adding force feedback to the impedance network and selection of virtual coupling form. Second, I/A and A/I H2PN’s are experimentally validated on HuRBiRT and resulting experimental networks are directly compared to those numerically formulated through use of HuRBiRT’s linearized dynamic models.
Improved Structural Joint Concepts
Authors: May Carl , Wilson Henry , Hethcock J. Donn , Davis Tim
Published: April 2008

The joining of composite materials used in airframe structures has always presented a challenge to the structural engineer. As part of a Survivable Affordable Repairable Airframe Program (SARAP) agreement, research on three advanced joining concepts was conducted to identify and validate designs that would provide improved structural efficiency when compared to conventional joining methods. The first involves using finger joints in thin laminates to produce a joint with high specific strength compared to typical joining methods. The second utilizes a derivative of needling for stabilized dry fabric pre-forms to improve through-the-thickness laminate and joint properties. The third concept focuses on compression preload to improve the performance of a typical lap joint. Within each concept, coupon or element tests were used to validate the performance of these alternative configurations. This paper presents both analytical predictions and test results documenting the effects of these improved joining methods.
Comparison of the Strain Localization Approaches: Viscoplasticity Theory and Gradient Dependent Theory
Authors: Voyiadjis George Z. , Abu Al-Rub Rashid K.
Published: April 2008

This work is focused on the comparison between the two strain localization techniques namely, the viscoplasticity and the gradient dependent theory. In the first approach a length-scale parameter is introduced implicitly through viscosity in order to address strain localization and material instability in the (initial) boundary value problems. The second approach is the enhanced nonlocal gradient-dependent theory which formulates a constitutive framework on the continuum level that is used to bridge the gap between the micromechanical theories and the classical (local) continuum. It is successful in explaining the size effects encountered at the micron scale and in preserving the well-posedeness of the (initial) boundary value problems governing the solution of material instability triggering strain localization. This is due to the explicit incorporation of an intrinsic material length scale parameter in the constitutive description. These numerical examples prove the excellent performance of the present frameworks in describing the strain localization problem.
Design of a Parametrically Excited Tuning Fork Microgyroscope
Authors: Lee Yongsik , Feng Z. C.
Published: April 2008

Parametrically excited tuning fork micro gyroscopes have several attractive features. Most of all, the excitation may be externalized, which could simplify the design and fabrication of micro gyroscopes. However, there are no readily applicable tools to guide the design of these gyroscopes since the gyro structures are more complex than those structures whose responses to parametric excitations are known and since finite element analysis tools are not capable of studying parametric excitations. In this work, we adopt a novel approach to obtain a simplified model of the parametrically excited structure. Parameters in the simplified model are obtained using dynamic analysis capability of typical finite element programs and static nonlinear analysis capabilities.
Solution of Abel’s Integral Equation Using Tikhonov Regularization
Authors: Daun K. J. , Thomson K. A. , Liu F. , Smallwood G. J.
Published: April 2008

This paper presents a method based on Tikhonov regularization for solving one-dimensional inverse tomography problems that arise in combustion applications. In this technique, Tikhonov regularization transforms the ill-conditioned set of equations generated by onion-peeling deconvolution into a well-conditioned set that is more stable to measurement errors that arise in experimental settings. The performance of this method is compared to that of onion-peeling and Abel three-point deconvolution by solving for a known field variable distribution from projected data contaminated with artificially-generated error. The results show that Tikhonov deconvolution provides a more accurate field distribution than onion-peeling and Abel three-point deconvolution, and is more stable than the other two methods as the distance between projected data points decreases.
A New Computational Method to Track a Liquid/Vapor Interface With Mass Transfer, Demonstrated on the Concentration Driven Evaporation From a Capillary Tube, and the Marangoni Effect
Authors: Rice Jeremy , Faghri Amir
Published: April 2008

A new computational liquid/vapor interface tracking technique is developed to model an interface between a liquid and a vapor including mass transfer. This technique does not require the use of an additional transport equation, as does the VOF method, while still being implemented without a complicated solution procedure. This new interface tracking technique is used to capture the liquid/vapor interface in a capillary tube of 100 μm scale. The diffusion driven evaporation process is studied, along with the Marangoni convection that is caused by the temperature gradient along the interface. The results are qualitatively and quantitatively compared to existing experimental data.
Analysis of Porous Wick Heat Pipes, Including Capillary Dry-Out Limitations
Authors: Rice Jeremy , Faghri Amir
Published: April 2008

A complete numerical analysis of heat pipes is performed with no empirical correlations while including the flow in a wick. The numerical model is validated from experimental and numerical work. Single and multiple heat sources were used as well as constant, convective and radiative heat sinks. The numerical model does not fix the internal pressure references by a point, but allows is to rise and fall based on the physics of the problem. Also, the capillary pressure needed in the wick to drive the flow is obtained for various heating configurations and powers. These capillary pressures, in conjunction with an analysis that predicts the maximum capillary pressure for a given heating load is used to determine the dry-out limitations of a heat pipe.
Turbulent Impinging Jet Into a Confined Porous Layer
Authors: de Lemos Marcelo J. S. , Graminho Daniel R.
Published: April 2008

Turbulent impinging jets on heated surfaces are widely used in industry to modify local heat transfer coefficients. The addition of a porous substrate covering the surface contributes to a better flow distribution, which favors many engineering applications. Motivated by this, the present work shows numerical results for a turbulent impinging jet against a cylindrical enclosure with and without a porous layer at the bottom. The macroscopic time-averaged equations for mass, momentum and energy are obtained based on a concept called double decomposition, which considers spatial deviations and temporal fluctuations of flow properties. The numerical technique employed for discretizing the governing equations is the control volume method in conjunction with a boundary-fitted non-orthogonal coordinate system. The SIMPLE algorithm is used to handle the pressure-velocity coupling. The influence of characteristics of the porous layer on the mean and statistical flow fields within the cylinder is presented.
Multidisciplinary Placement Optimization of Heat Generating Electronic Components on Printed Circuit Board in Channel Flow Forced Convection Using Artificial Neural Networks
Authors: Suwa Tohru , Hadim Hamid
Published: April 2008

A multidisciplinary placement optimization methodology for heat generating electronic components on printed circuit boards (PCBs) in channel flow forced convection is presented. In this methodology, thermal, electrical, and placement criteria involving junction temperature, wiring density, line length for high frequency signals, and critical component location are optimized simultaneously using the genetic algorithm. A board-level thermal performance prediction methodology based on channel flow forced convection boundary conditions is developed. The methodology consists of a combination of artificial neural networks (ANNs) and a superposition method that is able to predict PCB surface and component junction temperatures in a much shorter calculation time than the existing numerical methods. Three ANNs are used for predicting temperature rise at the PCB surface caused by a single heat flux at an arbitrary location on the board, while temperature rise due to multiple heat flux is calculated using a superposition method. Compact thermal models are used for the electronic components thermal modeling. Using this optimization methodology, large calculation time reduction is achieved without losing accuracy. For thermal model validation, the present thermal methodology predicts junction temperatures with maximum error of 1.8°C comparing to the conjugate solid/ fluid heat transfer analysis result. The present thermal modeling takes 12 seconds, while the conjugate analysis takes 30 hours for the validation on the same computer. To demonstrate the capabilities of the present methodology, a test case of component placement on a PCB is presented.
Analysis of Coupled Electromechanical Oscillators by a Band-Pass, Reduced Complexity, Volterra Method
Authors: Xiros Nikolaos I. , Georgiou Ioannis T.
Published: April 2008

Nonlinear analysis of a typical electromechanical coupled oscillator is approached by using Volterra polynomial series representation for nonlinear systems. The problem is formulated in a band-pass framework, allowing the study of transmission of power and information over the same line from the excitation voltage source to the final electromagnetic transducer stage. An input-output, black-box, monochromatic identification technique is applied, in order to obtain a simple, yet nonlinear, small-signal model for the low-pass modulating envelope of the excitation. The small-signal model consists of a low-order static polynomial nonlinearity intermitted between two linear MA filters. The procedure is carried completely in the frequency domain. The most important of the advantages, offered by the proposed methodology, is that identification is performed by employing only the fundamental harmonic component of the response to single sinusoidal inputs of various frequencies and amplitudes that sweep the band and range of interest.
Microforming: Study of Friction Conditions and the Impact of Low Friction/High-Strength Die Coatings on the Extrusion of Micropins
Authors: Krishnan Neil , Cao Jian , Dohda Kuniaki
Published: April 2008

Microforming is a relatively new realm of manufacturing technology that addresses the issues involved in the fabrication of metallic microparts, i.e., metallic parts that have at least two characteristic dimensions in the sub-millimeter range. The recent trend towards miniaturization of products and technology has produced a strong demand for such metallic microparts with extremely small geometric features and high tolerances. Conventional forming technologies, such as extrusion, have encountered new challenges at the micro-scale due to the influence of ‘size effects’ that tend to be predominant at this length scale. One of the factors that shows a strong influence is friction. This paper focuses on the frictional behavior observed at various sample sizes during micro-extrusion. A novel experimental setup consisting of forming assembly and a loading stage has been developed to obtain the force-displacement response for the extrusion of pins made of brass (Cu/Zn: 70/30). This experimental setup is used to extrude pins with a circular cross-section that have a final extruded diameter ranging from 1.33 mm down to 570 microns. The experimental results are then compared to finite-element simulations and analytical models to quantify the frictional behavior. It was found that the friction condition was non-uniform and showed a dependence on the dimensions (or size) of the micropin. The paper also investigates the validity of using high-strength/ low friction die coatings to improve the tribological characteristics observed in micro-extrusion. Three different extrusion dies coated with diamond-like carbon with silicon (DLC-Si), chromium nitride (CrN) and titanium nitride (TiN) were used in the micro-extrusion experiments. All the coatings worked satisfactorily in reducing the friction and correspondingly, the extrusion force with the DLC-Si coating producing the best results.
Experimental Determination of the Effect of Varying the Base Fluid on Static Thermal Conductivity of Nanofluids
Authors: Nara S. , Bhattacharya P. , Vijayan P. , Lai W. , Rosenthal W. , Phelan P. E. , Prasher R. S. , Song D. W. , Wang J.
Published: April 2008

The heat transfer abilities of fluids can be improved by adding small particles of sizes of the order of nanometers. Recently a lot of research has been done in evaluating the thermal conductivity of nanofluids using various nanoparticles. In our present work we address this issue by conducting a series of experiments to determine the effective thermal conductivity of alumina-nanofluids by varying the base fluid with water and antifreeze liquids like ethylene glycol and propylene glycol. Temperature oscillation method is used to find the thermal conductivity of the nanofluid. The results show the thermal conductivity enhancement of nanofluids depends on viscosity of the base fluid. Finally the results are validated with a recently proposed theoretical model.
A Scalable Silicon Micro-Reactor for Preferential CO Oxidation With an Integrated Platinum Heater
Authors: Dhingra Amit , Im Hong G. , Srinivas Sujit , Gulari Erdogan
Published: April 2008

Recent advances in PEM fuel cell systems have demonstrated their role in the production of clean and efficient power. However, due to complexities and safety concerns in the storage and transport of hydrogen, development of on-board fuel processing of hydrocarbon into hydrogen is being considered a critical issue in the success of the fuel cell technology in transportation application. In this paper, a novel concept of scalable silicon micro-reactor with an integrated platinum heater is developed for preferential CO oxidation. The performance of the micro-reactor is assessed and compared to a packed-bed reactor model. Complementary experimental and modeling efforts are made to identify the optimal thermal design parameters. It is demonstrated that the silicon micro-reactors successfully achieves the objectives of scalability without suffering from loss of efficiency due to the mass transfer limitations.
Predictive Models for Flank Wear in Near Dry Machining
Authors: Li Kuan-Ming , Liang Steven Y.
Published: April 2008

The objective of this paper is to present a methodology to analytically model the tool flank wear rate in near-dry turning. The resulting models can serve as a basis to minimize time-consuming machining tests in predicting tool life. Analytical models, including cutting force model, cutting temperature model, and tool wear model, are presented. The cutting force model was established based on Oxley’s model with modifications for lubricating and cooling effect due to the air-oil mixture in near-dry machining. The cutting temperature was obtained by considering a moving or stationary heat source in the tool. The tool wear model contained abrasive mechanism, adhesion mechanism, and diffusion mechanism. The important factors related to this model were contact stresses and temperatures that were obtained from the cutting force model and the cutting temperature model. To develop these models, a set of cutting experiments using carbide tools on AISI 1045 steels were performed to calibrate the coefficients in the models and to verify the proposed flank wear mechanisms. The comparisons between the model-predictive flank wear and experimental results showed that the flank wear in near dry machining can be estimated well by the proposed models. It was also found that the cutting velocity was a dominant factor among the cutting conditions.
Modeling and Design of Heavy Duty Hybrid Electric Vehicles
Authors: Pisu Pierluigi , Hubert C. , Dembski N. , Rizzoni G. , Josephson John , Russell James , Carroll Mark
Published: April 2008

A large scale design space exploration provides invaluable insight into vehicle design tradeoffs. Performing such a search requires designers to: • define appropriate performance criteria by which to judge the vehicles in the design space; • develop vehicle models to calculate the needed criteria; and • determine suitable velocity profiles as well as grade and terrain conditions to feed into the models. This paper presents a methodology for creating and conducting a design space exploration with particular application to heavy duty series hybrid electric-trucks.
Design of an All-Terrain Reconfigurable Modular Robot
Authors: Merino Carlos Santos , Blanch Jorge , Dede Mehmet Ismet Can , Tosunoglu Sabri
Published: April 2008

The purpose of this study is to develop a robotic platform which can be used in many dangerous or inconvenient tasks such as search and rescue operations, space exploration, hazardous material cleanup or as a simple service robot capable of navigating through houses and cities. In order to reduce the cost and development time of an all-terrain autonomous robot, a modular approach is used. The robot is designed as simple as possible by using one-degree-of-freedom modules that will allow the platform to reconfigure itself to use two different locomotion methods inspired by biological systems: Quadruped and caterpillar locomotion. This paper describes the development of modules that form the reconfigurable robot, and then focuses on the gait definitions of the crawling and quadruped modes of locomotion. A prototype of this robot has been built and the described gaits are tested at FIU’s Robotics & Automation Laboratory. Test results are also presented in this work.
Effect of Temperature on Impact Properties of Hybrid Fiberglass/Kevlar Laminate Composites
Authors: Salehi-Khojin Amin , Bashirzadeh Reza , Mahinfalah Mohammad , Jazar Reza Nakhaie
Published: April 2008

This paper demonstrates results of an experimental study on Kevlar/fiberglass composite laminates subjected to impact loading at variable temperatures. The effect of temperature on maximum energy, maximum impact force, and compression after impact was studied at several low velocity impact energy levels (8J, 15J, 25J). The temperatures considered were in the range of −50C to 120C. Results indicated that impact performance of these composites was affected over the range of temperature considered. Testing at ambient temperature is not fully sufficient and therefore additional testing must be performed for full understanding of composite laminate properties.
Robust Optimization for Smart Machining Systems: An Enabler for Agile Manufacturing
Authors: Deshayes L. , Welsch L. , Donmez A. , Ivester R.
Published: April 2008

This paper reports our efforts towards developing a mathematical and information framework for optimization of machining processes within a Smart Machining System (SMS). An SMS uses diverse integrated technologies that enable an enterprise to: (1) produce the first and every product correct; (2) improve the response of the production system to changes in demand (just in time); (3) realize rapid and agile manufacturing; and (4) provide data to the rest of the enterprise as needed. Optimization of machining processes is an important component of an SMS and contributes to realizing these capabilities. Based on a prototype, we demonstrate the concepts for robust optimization within an SMS and develop requirements and challenges for robust optimization in an SMS.
Control of a Tuned Vibration Absorber Based on SMA Wires
Authors: Williams Eric , Elahinia Mohammad H. , Koo Jeong-Hoi
Published: April 2008

This paper presents the control simulation results of a tuned vibration absorber (TVA) that utilizes the properties of shape memory alloy (SMA) wires. A conventional passive TVA is effective when it is precisely tuned to the frequency of a vibration mode; otherwise, resonance may occur that could damage the system. Additionally, in many applications the frequency of the primary system often changes over time. For example, the mass of the primary system can change causing a change in its natural frequency. This frequency change of the primary system can significantly degrade the performance of the TVA. To cope with this problem, many alternative TVA’s (such as semiactive, adaptive, and active TVA’s) have been studied. As another alternative, this paper investigates the use of Shape Memory Alloys (SMA’s) in passive TVA’s in order to improve the robustness of the TVA’s subject to mass change in the primary system. This allows for effective tuning of the stiffness of the TVA to adapt to the changes in the primary system’s natural frequency. To this end, a close-loop control system adjusts the applied current to the SMA wires in order to maintain the desired stiffness. The model, presented in this paper, contains the dynamics of the TVA along with the SMA wire model that includes phase transformation, heat transfer, and the constitutive relations. The closed-loop robustness analysis is performed for the SMA-TVA and is compared with the equivalent passive TVA. For the robustness analysis, the mass of the primary system is varied by ± 30% of its nominal mass. The simulation results show that the SMA-TVA is more robust than the equivalent passive TVA in reducing peak vibrations in the primary system subject to change of its mass.
Sub-Frame Design for a Hydraulic Hybrid Vehicle System
Authors: Wang Hui , Liu Yuanyuan , Ma Zheng-Dong
Published: April 2008

Hybrid vehicles are gaining increasing popularity in recent years, and there are three major types of hybrid systems, hybrid hydraulic, hybrid electric, and hybrid fuel cell. The hydraulic system offers great advantages for vehicles operating in stop-and-go conditions because the reversible hydraulic pump/motor can capture large amounts of energy when the brakes are applied, and this energy is released through the hydraulic pump/motor to propel the vehicle. The key component in this new system is a HLA (Hydraulic Launch Assist) unit, which employs an advanced hydraulic hybrid power train system. Technical challenges with hydraulic hybrids include packaging and noise issues. HLA is an over 600 lbs system, and to fit it into a traditional designed vehicle, as well as to fit possibly multiple candidate platforms, the design of a sub-frame that can mount the HLA to the vehicles is a critical task. Because HLA system development is an on-going work, different structural problems emerge during this process. Therefore, an efficient design system is necessary to address the problems in the up-front design stage. Function-Oriented Material Design (FOMD) with special topology optimization techniques, such as multi-domain multi-step topology optimization, is a tool suitable for this task. The theoretical background is described and sub-frame design process is summarized in this paper. The effectiveness of the design system is demonstrated through design examples. The design method and procedure proposed in this paper is applicable to other vehicle structural design problems, which will reduce the design cycle and achieve the required functionalities in an efficient way.
Formation Control of Under-Actuated Robotic Boats
Authors: Fahimi Farbod , Rineesh S. V. Sudhil , Nataraj C.
Published: April 2008

Feedback control laws for controlling multiple robotic boats in arbitrary formations are proposed. The presented formation control method uses only local sensor-based information. The method of input-output linearization has been used to exponentially stabilize the relative distance and orientation of neighboring boats with a three-degree-of-freedom dynamic model. It is shown that the internal dynamics of the system is also stable. The use of these control laws is demonstrated by computer simulations. These controllers can be utilized to control an arbitrarily large number of robotic boats moving in very general formations.
NIOSH AutoROPS Research to Practice: Zero Turn Commercial Mowers
Authors: McKenzie E. A. , Etherton J. R. , Harris J. R. , Cantis D. M. , Lutz T. J.
Published: April 2008

Marketing new safety devices is a critical function on the research-to-practice path. This path to adoption of new safety technology is not always straightforward. The National Institute for Occupational Safety and Health (NIOSH) Automatically deployable Rollover Protective Structure (AutoROPS) is a passive safety device developed to protect tractor operators in an overturn event. Tractor overturns kill more than 100 farmers each year in the United States (Myers, 2003). This technology was first designed to target the agricultural low-clearance environments involving “low-profile” tractors where traditional ROPS may not be feasible. These tractors are exempted from ROPS use as stated in OSHA 1928.51(b) (5) (i & ii). The upper portion of the AutoROPS remains retracted under low clearance areas but deploys to full height when an overturn is detected. The AutoROPS has been tested under both field and laboratory conditions prescribed in the ROPS performance standard, SAE J2194. To translate successful research into occupational practice, NIOSH formed a partnership with FEMCO, a ROPS manufacturer, in 2003. FEMCO’s efforts found Scag Power Equipment, a zero-turn commercial mower manufacturer. NIOSH has partnered with them as well. The Scag AutoROPS has been successfully laboratory tested to industry standards. Preliminary field evaluations of the deployment system have been conducted in preparation for field upset tests. Product development, test procedures, test results, and current marketing efforts are presented on this innovative safety device.
Investigation of Elliptical Cooling Channels for a Naval Electromagnetic Railgun
Authors: Kealey Elizabeth R. , Joyce Peter J. , Cerza Martin , Smith Andrew N.
Published: April 2008

Elliptical cross sections were examined for the design of cooling channels subject to biaxial and uniaxial compressive loading conditions based on an Electromagnetic (EM) Railgun. Elliptical shapes were considered due to the high surface area available for convection, relatively low impact on the stress distribution, and low stress concentration effect. The heat transfer capability of elliptical channels is maximized based on the applied heat flux and given flow conditions, by treating the channel as a variable area fin and varying the major and minor axis of the elliptical cross-section channel as well as the distance between channels. The optimal channel shape is further constrained by the applied compressive stresses. In order to test the thermal aspect of the design, a representative set of channels were machined into 1/3 scale copper rails using wire EDM. Tests were performed using a steady state heat flux to determine the overall heat transfer coefficient in order to verify the thermal calculations. In order to verify the structural aspect of the design, a numerical study of the stress concentration factors was performed. The results of both the thermal testing and numerical study were found to be in reasonable agreement with the prediction results.
Proper Powertrain Modeling for Engine-in-the-Loop Simulation
Authors: Fathy Hosam K. , Ahlawat Rahul , Stein Jeffrey L.
Published: April 2008

This paper presents a proper model of a HMMWV’s four-speed automatic transmission powertrain. The model is simultaneously accurate enough to capture important powertrain transients and fast enough to run in real time. The model’s parameters are scaled to match a powerful new diesel engine proposed for HMMWV propulsion. This enables real time hardware-in-the-loop engine testing and emissions measurement under realistic drive cycles. The algorithm used for proper powertrain modeling is easy to automate, which decreases the time needed to create simulation models for hardware-in-the-loop environments. Furthermore, the paper highlights the importance of scalability and validity in the context of proper modeling.
A Generalized Minmax Influence Coefficient Method for Flexible Rotor Balancing
Authors: Untaroiu Costin , Allaire Paul
Published: April 2008

Rotor balancing is a requirement for the smooth operation of high-speed rotating machinery. In field balancing, minimization of the residual vibrations at important locations/speeds under practical constraints is usually a challenging task. In this paper, the generalized minmax coefficient influence method is formulated as an optimization problem with flexible objective functions and constraints. The optimization problem is cast in a Linear Matrix Inequality (LMI) form and a balancing code is developed to solve it. Two balancing examples are run to verify the efficiency and flexibility of the proposed method. Over the existing methods, current method is more flexible for the various requirements encountered in field balancing and can be solved accurate with current mathematical software.
Simulations of Fault-Adaptive Control
Authors: Byreddy Chakradhar , Frampton Kenneth D.
Published: April 2008

The objective of this work is to detect failures in a vibration control system and adapt the control system in order to maintain optimal performance. Fault detection and isolation (FDI) filters, which are a subset of state observers specifically designed to detect and identify known types of system failures, are used to detect sensor and actuator malfunctions. The output of such filters is used to reconfigure feedback compensators in order to maintain closed loop objectives. Such reconfiguration allows the system to continue operating optimally under certain system failures. Simulations have been performed for vibration control of a simply supported beam. The simulation is allowed to “fail” in certain pre-defined ways. FDI filters designed to detect these failures operate in parallel with the compensator. When a failure occurs the FDI filter output is used to switch to a new compensator that is appropriate for the new system condition. There are several challenges inherent in this effort but the most important is the management of compensator switching. Since switching involves system discontinuity, therefore stability of the system is very difficult to guarantee. Even if the plant and compensator are dissipative, stability cannot necessarily be proven. Simulation results will demonstrate some of these challenges and the effectiveness of this approach for maintaining suitable closed loop performance in the presence of system failures.