bluuebunny/crossref_metadata_2025 huggingface dataset:
Inverse Wheel Dynamics
Authors: Vantsevich V. V.
Published: April 2008

Wheel dynamics is a significant component of vehicle dynamics and performance analysis. This paper presents an innovative method of studying wheel dynamics and wheel performance control based on the inverse dynamics formulation of the problem. Such an approach opens up a new way to the optimization and control of both vehicle dynamics and vehicle performance by optimizing and controlling power distribution to the drive wheels. An equation of motion of a wheel is derived first from the wheel power balance equation that makes the equation more general. This equation of motion is considered the basis for studying both direct and inverse wheel dynamics. The development of a control strategy on the basis of the inverse wheel dynamics approach includes wheel torque control that provides a wheel with both the referred angular velocity and rolling radius and also with the required functionals of quality. An algorithm for controlling the angular velocity is presented as the first part in the implementation of the developed strategy of the inverse wheel dynamics/performance control.
The Stick Motion of a Harmonically Excited, Friction-Induced Oscillator on a Sinusoidally Traveling Surface
Authors: Luo Albert C. J. , Gegg Brandon C. , Suh Steve S.
Published: April 2008

In this paper, the methodology is presented through investigation of a periodically, forced linear oscillator with dry friction, resting on a traveling surface varying with time. The switching conditions for stick motions in non-smooth dynamical systems are obtained. From defined generic mappings, the corresponding criteria for the stick motions are presented through the force product conditions. The analytical prediction of the onset and vanishing of the stick motions is illustrated. Finally, numerical simulations of stick motions are carried out to verify the analytical prediction. The achieved force criteria can be applied to the other dynamical systems with nonlinear friction forces possessing a CO - discontinuity.
An Investigation of Particle Injection and Resulting In-Flight Particle Behavior During Air Plasma Spraying
Authors: Zhang W. , Srinivasan V. , Zheng L. L. , Sampath S.
Published: April 2008

In this article we present our studies on the role of particle injection on the in-flight particle characteristics in an external orthogonally injected air plasma spray system. The influence of carrier gas on the in-flight particle state has been investigated, experimentally and using simulation, for Yttria Stabilized Zirconia (YSZ) thermal spray powder processed in an Ar-H2 plasma. Diagnostic tools such as IPP and SPT have been used to measure the plume characteristics and ensemble temperature while DPV-2000 has been used to measure the distributions of individual particle characteristics such as temperature, velocity and size, at the point of the maximum particle flux and at various points (square grid) in the plume cross-section. Three-dimensional simulations have been performed for the cases presented in the experiments. Specifically, the effects of carrier gas flow rate on the in-flight particle characteristics were studied at multiple stand-off distances. Simulation results agree well with the experimental observation that the particle velocity and temperature will increase with the plume angle and then decrease after reaching a maxima for a given process parameter combination and stand-off distance. This maxima has been observed at the same plume angle for different process parameter combinations. The results of this study are currently being used to 'optimize' the particle injection and trajectory, which enables better understanding of the influence of plasma forming and stabilizing parameters (gas flows and arc current) on the in-flight particle behavior.
Combustion Hot Spot Analysis for Single-Side-Fired Tubes in a Floor-Fired Box Furnace
Authors: Prasanna D. , Aung K.
Published: April 2008

The combustion zone in a process heater can be treated as an agglomeration or series of confined jet-flame systems that emanate from burner tiles and expand to an allocated fire box crosssectional area. Possible failure of the tubes containing the process fluid due to local over heating requires the ability to predict detailed radiative heat flux and temperature distribution from the knowledge of the inlet and boundary condition and the system geometry. An analytical model has been developed which is capable of determining the heat transferred by radiation. The variation of the dimensionless heat flux number with varying firebox to burner area ration, length to clearance ratio and a dimensionless distance along the combustion zone is studied. A C-program is developed which displays these results for various single-side-gas-fired tubes in floor-fired box furnace geometry. Results were also displayed for the variation of heat flux along the length of the vertical tube carrying the process fluid for single side fired tubes in a two-burner floor-fired box. The results of the analytical model developed are in good agreement with the published data.
Influences of Cross-Sectional Geometry and Surface Roughness on the Compression Stability in Upsetting High Aspect-Ratio Shaped Billets by FE Analysis
Authors: Hsu Yuan-Chuan , Lin Heng-Sheng , Yang Tung-Sheng
Published: April 2008

Metal forming for micro or mini-parts is a new developing trend in the metal forming application. The analysis of billet compression stability in upsetting is essential in selecting forming parameters and determining the size effect. The current study aims to explore the influence of billet geometry and surface roughness on the compression stability in upsetting high aspect-ratio shaped billets. 3D finite element simulation was employed to analyze the influence of surface roughness on the end faces of the billet and shapes profiles of the billet cross-section, on buckling in upsetting mini-size billets. Simulation results indicated that the rougher the contact surface, the lower was compression stability in upsetting the billets. In addition, the cross-sectional shape of the billet affected the compression stability in upsetting. Mini billets with larger shape factors would lead to higher compression stability.
A Modeling Approach for Hydrogen-Doped Lean Premixed Turbulent Combustion
Authors: Muppala Siva P. R. , Papalexandris Miltiadis V.
Published: April 2008

In this study, we investigate some preliminary reaction model predictions analytically in comparison with experimental premixed turbulent combustion data from four different flame configurations, which include i) high-jet enveloped, ii) expanding spherical, iii) Bunsen-like, and iv) wide-angled diffuser flames. The special intent of the present work is to evaluate the workability range of the model to hydrogen and hydrogen-doped hydrocarbon mixtures, emphasizing on the significance of preferential diffusion, PD, and Le effects in premixed turbulent flames. This is carried out in two phases: first, involving pure hydrocarbon and pure hydrogen mixtures from two independent measured data, and second, with the blended mixtures from two other data sets. For this purpose, a novel reaction closure embedded with explicit high-pressure and exponential Lewis number terms developed in the context of hydrocarbon mixtures is used. These comparative studies based on the global quantity, turbulent flame speed, indicate that the model predictions are encouraging yielding proper quantification along with reasonable characterization of all the four different flames, over a broad range of turbulence, fuel-types and for varied equivalence ratios. However, with each flame involved the model demands tuning of the (empirical) constant to allow for either or both of these effects, or for the influence of the burner geometry. This provisional stand remains largely insufficient. Therefore, a submodel for chemical time scale from the leading point analysis based on the critically curved laminar flames employed in earlier studies for expanding spherical flames is introduced here. By combining the submodel and the reaction closure, the dependence of turbulent flame speed on physicochemical properties of the burning mixtures including the strong dependence of preferential diffusion and/or Le effects can be determined.
A Rectified Statistical Energy Analysis Method Using Finite Element Analysis
Authors: Wu Xian-Jun , Cao Jian-Hua , Zhu Shi-Jian
Published: April 2008

Two parameters, namely modal number (Nm) and modal overlap factor (Mo), are used as the indicators of the reliability of SEA prediction. It is suggested that Mo>1 and Nm>5 can be used to judge if the SEA prediction is reliable in prediction of plate vibration. In the mid-frequency, those conditions are hard to satisfy. Although it takes long time and great expense and even it is impossible to apply finite element analysis to the whole structure, it is economically to calculate a local single part and coupled parts. If the value of input power and coupling loss factor can be replaced by the value calculated by FEM, the precision of SEA can be greatly improved. Calculation example was given and the validity was proved.
A Successful Format for Semester-Long, Design, Build, and Test Early Design Projects
Authors: Bannerot Richard
Published: April 2008

This paper will present the philosophy and describe the lessons learned from the author's fifteen years of experience in developing semester-long, team, design, build, and test projects appropriate for an introductory engineering design course. The topics covered will be: project expectations, the content and organization of the course, the issues associated with the project, examples of project statements and student solutions, a list of the "DO's" and "DO NOT's" for project conception, development, expectations, management and evaluation. Specific issues that will be addressed are: team formation, team size, team mentoring, varying skill levels between teams, spreading the "pain", discouraging last minute construction, grading methodology, reporting requirements, design for assembly, monitoring, and project selection/development. Issues related to project selection/development are safety, compete against the clock not each other, limited operator participations, expectations, design testing and evaluation, and esthetics. Student feedback is presented on whether project outcomes were satisfied and their feelings about working in teams and competing.
Modeling and Simulation of Ship System-of-Systems With Wireless Network Inserted for On-Ship Communications
Authors: Mahulkar Vishal , Adams Douglas , Chaturvedi Alok , Lin Longbi , Shroff Ness
Published: April 2008

The objective of the research is to develop an agent based methodology for modeling a naval ship environment as a system-of-systems. A ship environment consists of complex interconnected systems such as the infrastructure, crew, and the work flow, which poses a challenge to capability and systems planning. By studying the real-time interactions between these systems, one can help make decisions about new technology to be inserted on a ship. A simulation model based on an agent-based modeling methodology is constructed in MATLAB along with a graphical user interface to simulate workflow scenarios for maintenance, troubleshooting, and watch duties described in predefined XML files in a zone of the ship. The environment consists of crew agents modeled with limited intelligence and behavioural traits, machinery with sensors, equipment consuming power, mobile and stationary network nodes and models for data transfer over the network, crew mobility, power distribution and trimming. Results demonstrate the robustness of powering network nodes over Ethernet. One key result of the simulation model demonstrates the relative effectiveness of network access point locations; a counter intuitive decrease in workflow efficiency occurs due to a new technology inserted to enable wireless access.
Modeling of Ion Transport in High Strain Ionomers by Monte Carlo Simulation Compared to Continuum Model
Authors: He Xingxi , Leo Donald J. , Wallmersperger Thomas
Published: April 2008

The transport of charge due to electric stimulus is the primary mechanism of actuation for a class of polymeric active materials known as ionomeric polymer transducers (IPTs). A two-dimensional ion hopping model has been built to describe ion transport in the IPT. In a Monte Carlo simulation, a square lattice of 50nm × 50nm is investigated containing 200 cations and 200 anions. Step voltages are applied between the electrodes of the IPT, causing the thermally-activated hopping between multiwell energy structures. The energy barrier height includes three parts: intrinsic energy, energy height due to the electric field and energy height due to ion-ion interactions. Periodic boundary conditions have been applied in the direction perpendicular to the electric field. The influence of the electrodes on both faces of IPT is formulated by the method of image charges. The charge density profile over the material has been calculated by the ion distribution in steady state. The Monte Carlo simulation is repeated multiple times to obtain an average result of the charge density. The averaged profile shows regions of cation depletion close to the anode, charge neutrality in the central part and ion accumulation close to the cathode, which qualitatively agrees with the results from conventional continuum models. To quantatively examine the Monte Carlo simulation of the ion hopping model, comparisons with a computational model of transport and electromechanical transduction are performed. This computational model is based upon a coupled chemo-electrical multi-field formulation and computes the spatio-temporal charge density profile to an applied potential at the boundaries. It can be seen that both methods, the statistical theory and the continuum theory, match quite well and are both able to represent the actual behavior inside the IPT. Moreover, experiments are performed to validate the current density calculated by the Monte Carlo simulation. The active material is Nafion 117 (Dupont) in the form of a cantilevered transducer with conductive electrodes on both surfaces and with mobile Na+ counter-ions. Voltage inputs are provided by a dSPACE DS 1102 DSP and amplified using an HP power amplifier. The current is measured by placing a small resistor in series with the sample, between the sample and ground. The voltage across the resistor is amplified and measured by dSPACE. The electrical current is calculated by dividing the voltage drop across the resistor by its resistance. Current density in both simulation results and experimental results exhibits an exponential decay over time.
Nanoparticle Removal Using Laser Induced Plasma Shockwaves
Authors: Varghese Ivin , Peri M. D. Murthy , Zhou Dong , Kadaksham A. T. John , Dunbar Thomas J. , Cetinkaya Cetin
Published: April 2008

Nano-scale substrate cleanliness is an essential requirement in variety of nanotechnology applications. Currently, the detachment and removal of sub-100nm particles is of a particular interest and challenge in semiconductor manufacture, lithography, and nanotechnology. The proposed particle removal technique based on pressure shock waves generated by a laser induced plasma (LIP) core is of interest in various nano/micro fabrication applications in which the minimum feature size has been reducing rapidly. Any removal technique adopted in a fabrication process must be on the same shrinking feature reduction curve since, for device reliability, the minimum tolerable foreign particle size on a substrate depends on the minimum feature size on a nano/micro-system or device. In recent years, we have demonstrated that nanoparticles can be detached and removed from substrates using LIP shock wavefronts. While we have experimentally established the effectiveness of the LIP technique for removing nanoparticles in the sub-100nm range, the removal mechanisms were not well-understood. In the current work, we introduce a set of novel removal mechanisms based on moment resistance of the particle-substrate bond and discuss their effectiveness and applicability in laser-induced plasma shock nanoparticle removal. To gain better understanding for the detachment mechanisms, the resultant force and rolling moment induced on the nanoparticle by the LIP shockwave front need to be determined. Since, for sub-100nm nanoparticles, the Knudsen number Kn exceeds 0.1, the applicability of the Navier-Stokes equations for the gas motion becomes questionable as the continuum assumption for the medium breaks down due to the invalidity of the transport terms in these equations. Detachment and detachment mechanisms of nanoparticles from flat surfaces subjected to shockwaves are investigated by employing molecular gas dynamic simulations using the direct simulation Monte Carlo method and experimental transient pressure data. Two new mechanisms for nanoparticle detachment based on rolling moment resistance of the adhesion bond and the elastic restitution effect are introduced. As a result of present simulations, it is computationally demonstrated that the pulsed laser-induced shockwaves can generate sufficient rolling moments to detach sub-100nm particles and initiate removal. The transient moment exerted on a 60nm polystyrene latex (PSL) particle on a silicon substrate are presented and discussed.
A Dual Sensing Approach to Simultaneous Temperature and Pressure Measurement From Injection Mold Cavity
Authors: Fan Zhaoyan , Gao Robert X.
Published: April 2008

This paper presents the design and performance analysis of a self-energized wireless sensor capable of simultaneous pressure-temperature dual sensing from within a mold cavity. The sensor extracts energy from the polymer melt pressure differential during the injection molding process and uses ultrasonic pulses as the wireless information transmission carrier. Simultaneous acquisition of melt temperature and pressure and differentiation of the two parameters at the signal receiver's end are made possible by variations of two parameters related to the ultrasonic pulses: the number of ultrasound pulses and the carrier frequency. While the pressure is discretized and translated proportionally into a corresponding number of pulses by a threshold modulator, a temperature-sensitive oscillator module converts the melt temperature variations into a shift of the ultrasound carrier frequency. To quantitatively evaluate the effectiveness of transmission and retrieval of the dual sensing data, an analytical model is established that relates the sensor design to the molding process parameters. The developed technique is validated by the experimental data from a real physical model.
Embedding Multiple Assessments in Classroom Activities
Authors: Fuehne Joseph P.
Published: April 2008

The Mechanical Engineering Technology program of Purdue University at Columbus/Southeast Indiana is a small program with only two full-time faculty and typically has 4-8 graduates per year. In preparing for its first ever ABET accreditation evaluation in the fall of 2005, the faculty conducted a survey of graduates from the last three years and received nine responses. Such a small response contributed to the concern that this method of assessment might not provide much useful data regarding assessment of program outcomes and objectives. As a result of this and limited resources, the faculty of the MET program in Columbus focused their efforts on direct assessment of program outcomes by using classroom assignments, lab reports and exam questions. An example of an embedded assessment utilized by the MET faculty is a laboratory report. The Mechanical Engineering Technology program consists of many classes that have laboratory activities. The rubric used for lab reports is a fifteen part rubric that varies from 1 to 4. Lab reports are assessed for spelling/grammar, participation, calculations, appearance, analysis, summary, conclusions and drawings/diagrams among other categories. Assessments can be made of technical content (program outcome (PO 1), verbal communications including both written content and graphical communications (PO 3), experimental understanding and teamwork. While these assessments are useful for gauging learning and are used in the MET program continuous quality improvement process, they also make grading considerably easier. A two-page form was also developed which summarized the assessment points for each program outcome. The first page of the form includes the mission statements of Purdue University, the MET program objectives, the MET program outcomes, the core learning objectives of the particular course in which the assessment is performed and the details of the assessment point. These details include the specific core learning objective, the applicable program outcome and the rubric for the assessment. The second page of the form includes the results of the assessment, those teaching techniques that the faculty member wants to retain and those that he wants to change.
Control of the Clad Height in Laser Powder Deposition Process Using a PID Controller
Authors: Fathi Alireza , Durali Mohammad , Toyserkani Ehsan , Khajepour Amir
Published: April 2008

Laser Powder Deposition (LPD) process is an advanced material processing technique which has many applications. Despite this fact, reliable and accurate control schemes have not yet fully developed for the process. In this paper, the problem of controlling the clad height in the LPD process is studied. Due to a faster response of the process to change in scanning velocity over the laser power, the scanning velocity is selected as the input control variable. Since the governing equations of the LPD process are complex for designing a controller, an identified nonlinear dynamic model is used. The model is a Hammerstein model with a linear dynamic and a nonlinear memoryless block. The model parameters are identified offline using experimental data. The controller has a proportional-integral-derivation (PID) architecture. The controller was implemented on the real plant to asses its performance in the fabrication of several metallic parts composed of stainless steel.
Temporal Modulation of Electroosmotic Micropumps
Authors: Laser Daniel J.
Published: April 2008

This paper reports on analytical and experimental studies of transient effects in electroosmotic (EO) micropumps, focusing on an EO micropump operational paradigm of practical importance: the use of variable-duty-cycle square wave driving voltages. Models of transient effects in EO micropumps are evaluated and developed, and load inertia as well as thermal and diffusion effects are considered. Detailed models, based on solutions for electroosmotic flow between infinite parallel plates, are presented for slit capillary array EO micropumps with slit half-width on the order of one micron. Driving typical microfluidic system loads, analysis by analogy to Stokes' second problem predicts pseudosteady electroosmotic flow in these micropumps for input frequencies up to 100 Hz, with attenuation of high-frequency components of square-wave inputs due to load inertial effects. In experiments with slit capillary array electroosmotic micropumps driven by 10 Hz square waves, micropump output is observed to be generally nonlinear with duty cycle, with significant flow rate enhancement relative to constant-voltage operation at duty cycles above 40%. Lateral diffusion during temporary zero-field conditions may lead to a slight increase in time-averaged zeta potential for square-wave-driven EO micropumps.
The Effect of Loading on Yaw Dynamics of Buses
Authors: Yu Nan , Muthiah Saravanan
Published: April 2008

Vehicle dynamics is closely related to traffic safety, especially in emergency situations. The behavior of a vehicle needs to be stable, predictable, and responsive in all situations to guarantee the safety of the vehicle and that of the overall transportation system. During daily services, the static axle loads of a transit bus can change by almost 100% on the front axle and 40% on the rear axle. As a result, the location of center of gravity, suspension compliance, tire cornering stiffness, the yaw moment of inertia, and many other vehicle parameters vary significantly, which will directly influence the dynamical properties of the vehicle. In this paper, the effects of changes in weight and weight distribution on the yaw characteristics of a 12-meter transit bus are investigated both analytically and numerically. Results obtained using both methods show a good match.
Coupling Analysis of Fracture Mechanics and Damage Mechanics for Fiber-Reinforced Asphalt Concrete Pavement
Authors: Sun Yazhen , Liu Jiemin , Yu Tianqing
Published: April 2008

The initial damage and fracture zone are determined by the approach of coupling analysis of fracture mechanics and damage mechanics. An optimum fiber content of 0.2% in the asphalt concrete is proposed in comparison of the results obtained from composite theory with that obtained from the splitting tests. Crack growth with number of load cycles and fiber mass fraction of asphalt concrete pavement in which an initial surface crack of 4 cm length is included under cyclic temperature loading (-15°C) is simulated using damage mechanics theorem. By computing fatigue life, a new type of fiber-reinforced asphalt concrete pavement is developed.
Microbial Dynamics Subject to Metabolic Mass Transfer
Authors: Vadasz Johnathan
Published: April 2008

Accounting for metabolic mass transfer and abiotic resource dynamics is not common in modeling microbial population growth. In this paper it is demonstrated that the latter is an essential feature that needs to be considered if reliable results are sought. The results of a model that takes the metabolic mass transfer and abiotic resource dynamics into account are shown to capture a variety of features that appear in experiments such as a Lag phase, a Logarithmic Inflection Point, growth followed by decline and oscillations. The results have a wide variety of implications and applications, from food microbiology and wine fermentation, up to human cell growth, where the latter includes tumor growth.
Low Velocity Impact Analysis of Functionally Graded Circular Plates
Authors: Larson Reid A. , Palazotto Anthony
Published: April 2008

Functionally graded materials (FGMs) are advanced composites with mechanical properties that vary continuously through a given dimension. FGMs have generated a great deal of interest in recent years due to their flexibility for use in a wide variety of environments, including those structural applications where extreme thermal and corrosion resistance are required. In this paper, analyses will be performed given an impact event that occurs between a spherical projectile and a functionally graded circular plate with both simply supported and clamped boundary conditions. The circular plates are constructed using zirconia and aluminum as constituents blended through the thickness in various configurations using a power-law distribution. The analyses will assume that the classical rule-of-mixtures (ROM) approach will sufficiently describe the macro-mechanical properties for the graded plates. First, impact response equations developed for composite materials are applied to estimate the impact force and maximum deflection of a functionally graded plate. Next, the elastic wave response of the functionally graded plate is predicted using the classic wave equation applied to the graded plate and the impact event. Finally, finite element simulations are developed to compare the analytical solutions to numerical results from a commercial software program. The degree of correlation between the analytical predictions and the finite element simulations will provide insight into the validity of the ROM assumption and provide a baseline for estimating impact behavior of functionally graded plates.
Platinum Microelectrodes in Polymeric Microfluidic Chips: A New Fabrication Approach
Authors: Huda Nazmul , Dutta Prashanta
Published: April 2008

Platinum microelectrodes become essential components in microfluidic devices for separation, pumping, sensing, and other bio-analyses. Due to their chemical inertness, several research groups have developed microfluidic devices with integrated platinum electrodes on silicon, quartz, or glass substrates. However, no techniques have been reported so far for depositing platinum electrodes in polymeric microchannels. In this study, a novel fabrication scheme for forming integrated microelectrodes in a poly-dimethyl-siloxane (PDMS) microchip is described. The electrode fabrication technique consists of photolithography, thermal processing, sequential sputtering of titanium and platinum and stripping off photoresist, while soft-lithography is used to form the microfluidic channels on PDMS. This approach facilitates precise positioning of the electrodes with a micron-sized gap between them, and it can be used for both low and high aspect ratio channels. The platinum electrodes, formed on the PDMS channel surface, demonstrated very good interfacial adhesion with the substrate due to the use of a very thin titanium layer between the platinum and PDMS. The surface roughness of the electrodes was found around ±50 nm.
The Vibration of Two Axially Translating Strings Interconnected by Winkler Elastic Foundation
Authors: Gaith Mohamed , Muftu Sinan
Published: April 2008

The transverse vibrations of two translating strings interconnected by a Winkler elastic foundation, and subjected to axial loading are investigated. The system of governing partial differential equations of this gyroscopic system is cast in the first order canonical form. It is shown that the natural frequencies are composed of two infinite sets, representing in-phase and out-of-phase vibrations of the two strings. The effects of the axial tension ratios of the two continuous media, as well as the effects of the elastic foundation stiffness are investigated. In general, it is found that the natural frequencies increase with increasing elastic stiffness of the foundation. It is found that the elastic foundation does not alter the critical speed, but different mass and tension ratios do.
Analytical and Experimental Natural Frequencies of Transverse Vibration of Sandwich Beams Interconnected by Winkler Elastic Foundation
Authors: Gaith Mohamed , Masters James , Muftu Sinan
Published: April 2008

The free transverse vibration of an elastically connected axially loaded double beam system for different materials and geometry were measured experimentally and analyzed theoretically. The theory predicts that natural frequencies of the system are composed of two infinite sets, describing in-phase and out-of-phase vibrations. It is observed, for the case of identical beams, that the in-phase frequencies are independent of the elastic foundation stiffness and its frequencies are identical to a single beam with the same boundary conditions. To compare and verify the accuracy and reliability of theoretical models, experimental measurements of natural frequencies of free vibration of axially tensioned, double beams interconnected by a silicone rubber foundation with fixed-fixed supported conditions are conducted. The first four synchronous natural frequencies were measured, and they were found to increase with increasing tension. The experiments showed that the synchronous natural frequencies of axially tensioned double beam system with fixed-fixed end conditions are in excellent agreement with those for a tensioned single beam with the same end conditions. The asynchronous mode frequencies are not observed, and believed to be due to the existence of damping properties in the elastic foundation, which suppressed the out-of-phase (asynchronous) mode frequencies.
Fabricating a Plastic Microfluidic Device for Protein Synthesis
Authors: Mei Qian , Fredrickson Carl K. , Simon Andrew , Fan Z. Hugh
Published: April 2008

We developed an array device consisting of miniaturized wells and a mechanism of fluid manipulation for cell-free protein synthesis. The array offers high-throughput protein production, matching the format of gene discovery. Each unit in the array is for synthesis of one individual protein and it consists of a tray chamber and a well chamber. The tray chamber is for in vitro protein synthesis reaction, while the well functions as a nutrient reservoir. The tray and well are separated by a dialysis membrane, which is glued to the bottom of the tray. The connection between the tray and the well provides a means to supply nutrients and remove the reaction byproducts. The device was demonstrated by synthesis of green fluorescent protein (GFP). The effectiveness of the device design on the protein production yield has been studied. The resultant advantages due to miniaturization include rapid analysis, less consumption of samples and reagents, and the decrease in the cost of protein synthesis.
Autotuning of A PID Controller for an Active Vibration Suppression Device for the Treatment of Essential Tremor
Authors: Stone Nicholas , Kaiser Kenneth , White Robert D.
Published: April 2008

Essential Tremor (ET) is a motion disorder which affects as many as one in 20-25 adults over the age of 40 [1]. Leblanc [2] proposed a device which consists of four linear actuators attached to a patient's wrist in an effort to actively suppress the tremor. This paper demonstrates experimentally a simplified version of that device. The system was tested on a stand designed to simulate an adult lower arm with a tremor in the horizontal plane. A single linear inertial actuator was attached to the "wrist" of the test stand. An accelerometer attached on the opposite side of the arm provided feedback to the controller. This paper demonstrates this system operating to produce 20%-60% vibration reduction in the 6-13 Hz bandwidth.
Fluid Flow in Nanometer Scale Channels: Effects of Polymer Coating
Authors: Qiao R. , He P.
Published: April 2008

Electroosmotic flow is one of the most important fluid transport mechanism in nanofluidic systems due to its ease-of-control and excellent scaling behavior. In this paper, we report on the atomistic simulation of electroosmotic flow regulation by coating the channel surface with a thin layer of polymers. While such coating is applied routinely in practice, the fundamental mechanism of the flow control is not well-understood. We show that the flow depends both on the polymer type and coating density. A detailed analysis of these results indicates that the flow regulation has both a hydrodynamic origin and a physio-chemical origin. The results highlight the need to integrate physical chemistry into the fluid mechanics for a fundamental understanding of the fluid transport at nanoscale.
Design and Control of the Angular Acceleration of a Hydraulic Rotary Actuator to Simulate a Flexible Joint Robot
Authors: Dezfulian Shahram , Burton Richard , Fotouhi Reza , Bitner Doug
Published: April 2008

The objective of this work was to design and implement an experimental hydraulic system that simulates joint flexibility with the ability of changing the joint flexibility's parameters. Such a system could facilitate future control studies by reducing investigation time and implementation cost of research. It could also be used to test the performance of different strategies to control the movement of flexible joint manipulators. A hydraulic rotary servo actuator was used to simulate the action of a flexible joint robot manipulator. A challenging task since the control of angular acceleration was required. A single-rigid-link, elastic-joint robot manipulator was modeled using Matlab®. Joint flexibility parameters such as stiffness and damping, could be easily changed. This simulation could be referred to as "function generator" to drive the hydraulic flexible joint robot. In this study the angular acceleration was used as the input to the hydraulic rotary actuator and the objective was to make the hydraulic system follow the desired acceleration in the frequency range specified. The hydraulic system consisted of a servo valve and rotary actuator. A hydraulic actuator robot was built and tested. The results indicate that if the input signal had a frequency in the range of 5 to 15 Hz and damping ratio of 0.1, the experimental setup was able to reproduce the input signal with acceptable accuracy. Because of the inherent noise associated with the measurement of acceleration and some severe nonlinearities in the rotary actuator, control of the experimental test system using classical methods was not as successful as had been anticipated. This was a first stage in a series of studies and the results provide insight for the future application of more sophisticated control schemes.
A Practical Method for Multi-Fault Diagnosis of Rolling Element Bearings Using Discrete Wavelet Transform and Support Vector Machine
Authors: Abbasion Saeed , Farshidianfar Anoushiravan , Irani Nilgoon , Bashari Mohamad
Published: April 2008

Due to importance of rolling bearings as one of the most widely used industrial machinery elements, development of proper monitoring and fault diagnosis procedure to prevent malfunctioning and failure of these elements during operation is necessary. For rolling bearing fault detection, it is expected that a desired time-frequency analysis method have good computational efficiency, and have good resolution in both, time and frequency domain. The point of interest in this investigation is the present of an effective method for multi fault diagnosis in such systems with optimizing signal decomposition levels by using wavelet analysis and support vector machine (SVM). The system that is under study is an electric motor which has two rolling bearings, one of them is next to the output shaft and the other one is next to the fan and for each of them there is one normal form and three false forms, which make 8 forms for study. The outcome that we have achieved from wavelet analysis and SVM are fully in agreement with empirical result.
Experimental Investigation of a Novel Blast Wave Mitigation Device
Authors: Su Zhenbi , Zhang Zhaoyan , Gogos George , Skaggs Reed , Cheeseman Bryan , Yen Chian Fong , Bitting Robert , Talsma Jay
Published: April 2008

A novel blast wave mitigation device was investigated experimentally in this paper. The device consists of a piston-cylinder assembly. A shock wave is induced within the cylinder when a blast wave impacts on the piston. The shock wave propagates inside the device and is reflected repeatedly. The shock wave propagation process inside the device lengthens the duration of the force on the base of the device to several orders of magnitude of the duration of the blast wave, while it decreases the maximum pressure by several orders of magnitude. Two types of experiments were carried out to study the blast wave mitigation device. The first type of experiments was done with honeycomb structures protected by the blast wave mitigation device. Experimental results show that the device can adequately protect the honeycomb structure. A second type of experiments was done using a Hopkinson bar to measure the pressure transmitted through the blast wave mitigation device. The experimental results agree well with results from a theoretical model.
Planning of Dynamic Compensation Manipulator Motions for Stability Enhancement of Mobile Manipulators by Soft Computing
Authors: Ghaffari Ali , Meghdari Ali , Naderi Davood , Eslami Sohrab
Published: April 2008

Mobile manipulators are developed in order to execute separately in various regions where there is not possibility for human to appear there. Recently, the size of mobile manipulators has been decreased according to their given tasks. For such systems, the stability issue is very important. The robot system should be able to keep itself in an optimal situation. For reaching to this goal, one can use a redundant degree of freedom for the mobile manipulator such that this redundancy makes it possible to recover the system's stability by dynamic compensatory motion of manipulator when the system is unstable. In this paper, we present an algorithm which is fast enough to stabilize the mobile manipulator with the best stability criterion based on a neural network and genetic algorithm which cooperate together. For applying the optimal values as the algorithm outputs to the appropriate joints, a PD controller is used. The significance of this algorithm is provided for a spatial mobile manipulator with a predefined trajectory of the end-effector and the vehicle.
Study on Whisker Outbreak on Thin Plating by Contact Force
Authors: Yamashita Takuma , Shibutani Tadahiro , Yu Qiang , Shiratori Masaki
Published: April 2008

Tin whisker outbreaks can pose problems on FFC/FPC (flat flex cable/flexible printed circuit) connectors in electronics components. Several mechanical loading tests for investigating whisker formation have been performed, however, the mechanical implications of the results remain unclear. The purpose of this study was to clarify whether the whisker formation mechanism on connectors is due to contact force. Using the creep properties collected from nanoindentaion tests, the stress evolution in plating is extracted. The behavior of the stress evolution was investigated by finite element analysis. During the test, the axial compressive stresses increase, although stress relaxation also occurs. The effect of substrate shape is also investigated and whiskering behavior due to stress was confirmed.
A Stress Analysis and Strength Evaluation of Scarf Adhesive Joints Subjected to Static Tensile Loading
Authors: Sawa Toshiyuki , Sasaki Masahiro , Hirayama Yuya
Published: April 2008

Scarf adhesive joints used in practice. However, the stress distributions and the joints strengths have not yet been fully elucidate. Important issues are how to determine the scarf angle in adherend and how to determine the adhesive properties. In this study, the stress distributions in scarf adhesive joints under static tensile loadings are analyzed using three-dimensional finite-element calculations. In the FEM calculations, the effects of Young's modulus of the adhesive, adhesive thickness, scarf angle of the adherend on the stress distributions at the adhesive interfaces are examined. The maximum principal stresses were calculated at every element at the interfaces. As the results, it is found that the maximum value of the maximum principal stress occurs at the edge of the adhesive interfaces (z=0, 1/s=1). It is also observed that the maximum value of the stress is the smallest, when the scarf angle is 60 degree. In addition, the joint strength is estimated using the interface stress. For the verification of the FEM calculations, the experiments were carried out to measure the strengths and the strains in the joints under static tensile loadings using strain gauges. Fairly good agreements are observed between the numerical and the measured results concerning the joint strength and the strains.
Extended Lindstedt-Poincare Method With Multiple Time Scales for Nonstationary Oscillations
Authors: Pusenjak Rudi R. , Avsec Jurij , Oblak Maks M.
Published: April 2008

The paper presents the extended Lindstedt-Poincare (ELP) method, which applies multiple time scales to treat nonstationary oscillations arising in dynamical systems with cubic non-linearities. The passage through the resonance is conducted to study deviations from the stationary response. The method is applied to the dynamical systems such as Duffing oscillator and van der Pol oscillator, whereat effects of varying the excitation frequency and varying the excitation amplitudes, respectively are studied. It is shown that application of multiple scales benefits to find more accurate expressions of stationary responses in comparison to the conventional Lindstedt-Poincare method and consequently contributes to the versatile and effective calculation of the nonstationary frequency response curves.
Heat Transfer Characteristics of a Loop Heat Pipe With Flat Evaporator Having a Bypass Line
Authors: Boo J. H. , Jung E. G.
Published: April 2008

It is common for loop heat pipes to experience start-up problems under low thermal loads. The start-up characteristic of a loop heat pipe with flat evaporator was investigated experimentally in this study. A bypass line was attached to the evaporator to alleviate the difficulties associated with startup. Axial grooves were provided in the flat evaporator to serve as a vapor passage. The evaporator and condenser had dimensions of 40 mm (W) by 50 mm (L). Coolant paths were machined inside the condenser. The inner diameters of liquid and vapor transport lines were 2.0 mm and 4.0 mm, respectively and the length of the two lines was 0.5 m each. The thermal load range was up to 80 W using methanol as a working fluid with the condenser temperature of 10°C at horizontal position. The results showed that a minimum thermal load for the startup was lowered by 37% when the bypass line was employed. However, a periodical performance variation was observed once the startup was achieved under very low thermal loads.
Investigation of a Centrifugal Pump Stage With Radial Impeller and a Pump Stage With Small Stage Diameter
Authors: Weiten Andreas , Hellmann Dieter-H.
Published: April 2008

For radial multistage centrifugal pumps a combination of a radial exiting impeller, a vaned diffuser and a row of return guide vanes is used for each stage of the pump. Hence the inner diameter of the stage casing is much larger than the diameter of the impeller. In case when the space for installing the pump is limited, for example in case of submersible pumps, a high number of pump stages is necessary to produce a sufficient hydraulic head. Pump stages with an impeller diameter equal to the inner diameter of the casing can reduce the number of the stages, but up to now the efficiency of such pumps is lower than the one of a conventional pump. Improving the design of these pumps in order to increase efficiency, stationary diffusers were developed at the Institute for Turbomachinery and Fluid mechanics at TU Kaiserslautern. While the pump liquid cannot exit the impeller in radial direction, the hub diameter is reduced by the width of the impeller at the outer diameter. Hence the pump liquid now exits the impeller in axial direction. This design affects both the hydraulic and the rotor dynamic performance of the pump. Furthermore the axial thrust has dropped, because the flow and the allocation of static pressure in the impeller side spaces has changes compared to radial pump stages. In this paper results of measurements of vibration and axial thrust at radial centrifugal pump with four stages are compared with these of a four stage pump with small stage diameter. Furthermore the hydraulic datas of both designs a presented.
Numerical Simulation of Subcooled Flow Boiling Heat Transfer in Helical Tubes
Authors: Jo Jong Chull , Kim Woong Sik , Choi Chang-Yong , Lee Yong Kab
Published: April 2008

This paper addresses the numerical simulation of two phase flow heat transfer in the helically coiled tubes of an integral type pressurized water reactor steam generator under normal operation using a CFD code. The single phase flow which flow downward direction in the shell side is also calculated together. For the calculation of tube side two-phase flow the inhomogeneous two-fluid model is used. Both the RPI (Rensselaer Polytechnic Institute) wall boiling model and the bulk boiling model are implemented for the numerical simulation and the computed results are compared with the available measured data. The conjugate heat transfer analysis method is employed to calculate the conduction in the tube wall with finite thickness and the convections in the internal and external fluids simultaneously so as to match the fluid-wall-fluid interface conditions properly. Both the internal and external turbulent flows are simulated using the standard k-ε model From the results of present numerical simulation, it is shown that the bulk boiling model can be applied to the simulation of two-phase flow in the helically coiled steam generator tubes. The results also show that the present simulation method is considered to be physically plausible when the computed results are compared with available previous experimental and numerical studies.