bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of Micromachined Piezoelectric Transducers Operating in a Flexural Mode
Authors: Fazzio R. Shane , Dauksher Walter , Goel Atul , Lamers Tina
Published: May 2009

Micromachined acoustic transducers have recently emerged in multiple application domains. Bulk acoustic resonators, for example, are extensively used as filters in the cellular handset industry. As another example, silicon capacitive microphones are rapidly replacing electret-condenser devices in consumer electronics platforms. Piezoelectric materials are commonly used in acoustic sensing applications. Combining micromaching with piezoelectric thin-films opens up possibilities of multiple new applications, in addition to the miniaturization of existing sensors. Applications may be as diverse as nondestructive test, acoustic imaging, vibration sensing, acceleration/force sensing, or electroacoustics. This paper presents analysis and measured behavior of micromachined devices constructed as a molybdenum, aluminum nitride, molybdenum trilayer and operating in a flexural mode. A theoretical analysis is derived using thin-plate bending theory. Finite-element simulation results of plate dynamics are examined, and sensitivities and linearity of manufactured devices are shown.
Analysis of Rigidity of a Shaft With a Crack Diagonal
Authors: Rabiela Homero J. , Cruz Isai´as H. , Miranda Gilberto A. , Villeda Mario G. , Sua´rez Victor C. , Santiago Raymundo A. , Gonza´lez Benjami´n V.
Published: May 2009

In this work the rigidity of a shaft with diagonal crack in its half part in its elastic range under static conditions simply supported in its ends and with concentrated load to the center is determined. The functional relationship for the variation of the second moment of area of their different cross-sections is deduced. For double numeric integration the slope and the deformation of the shaft is calculated. The frequency in which the cracked system would enter in resonance is calculated. The rigidity of the shaft with crack is smaller that the rigidity of the shaft without crack. Based on the results of the study is concluded that the rigidity of the shaft with crack can be evaluated with the procedure described to determine a range of frequencies in which the system would enter in resonance. Therefore the system would be unstable and detectable.
Molecular Dynamics Simulation of Electroosmotic Flow in Nanotubes
Authors: Chen Yunfei , Ni Zhonghua , Wang Guiming , Xu Dongyan , Li Deyu
Published: May 2009

The ion distribution and electroosmotic flow of sodium chloride solutions confined in cylindrical nanochannels with different surface charge densities are studied with molecular dynamics (MD). In order to obtain simulation results corresponding to more realistic situations, the MD simulation consists of two steps. The first step is used to equilibrate the system and obtain a more realistic ion distribution in the solution under different surface charge densities; and the second step is to apply an electrical field to drive the liquid and extract the electroosmotic flow information. Simulation results indicate that a higher surface-charge density corresponds to a higher peak of the counter ion concentration. Predictions based on the continuum theory were also calculated and compared with the molecular dynamics results. Even though the continuum theory cannot reflect the molecular nature of ions and water molecules, it is found that for low surface charge densities, the continuum theory can still give reasonable results if modified boundary conditions are applied. Charge inversion under high surface charge density has been predicted and observed recently, however, the simulation results do not indicate charge inversion even for a surface density as high as −0.34 C/m2. This might be due to the fact that we perform the MD simulations with monovalent ions, which have a tendency to suppress charge inversion, as demonstrated in the recent literature.
Low Temperature Growth of ZnO Nanowires for Hybrid Chemical Sensors
Authors: Walker Ebonee A. , Aga Roberto , Mu Richard
Published: May 2009

Hybrid nanocomposites, such as ZnO nanowires embedded in conducting polymers, are very attractive for chemical sensing applications. Previous studies have shown that tuning ZnO nanowire concentration with respect to the polymer can be employed to tailor chemical sensitivity and selectivity. In this work, we investigate the effect of ZnO nanowire growth time on the electrical transport properties of sensors with and without the polymer matrix. Varying growth times may affect wire lengths, wire concentration, as well as wire interconnectivity. Using pure Zn as the source, ZnO nanowires are grown on a glass substrate by a low temperature thermal evaporation method. Poly(3-hexylthiophene) is employed as the polymeric matrix to form a hybrid structure. The response to ethanol vapor of sensors with different nanowire growth times is evaluated.
An Efficient Numerical Scheme to Determine the Pull-In Parameters of an Electrostatic Micro-Actuator With Contact Type Nonlinearity
Authors: Joglekar Manish M. , Pawaskar Dnyanesh N.
Published: May 2009

In this article, we present an efficient numerical scheme based on the Rayleigh-Ritz method to determine the pull-in parameters of electrostatically actuated microbeams exploiting contact type nonlinearity. A case of an electrostatically actuated cantilevered microbeam is first analyzed using the Rayleigh-Ritz energy technique. The deflection of the microbeam is approximated by a polynomial trial function. The principle of the stationary potential energy leads to a highly nonlinear algebraic equation, which is solved to determine the deflected shape of the microbeam. A novel voltage iteration algorithm is implemented to determine the critical voltage at which the pull-in occurs. The analysis is then extended to the case of cantilever beam making use of the contact type nonlinearity to exhibit an extended travel range. The present case consists of a compression spring getting engaged at the cantilever tip at the critical point where the pull-in occurs. An increase in both travel range and pull-in voltage is observed with the introduction of the compression spring. A performance index is suggested, which combines the gain in the travel range together with the concomitant increase in the pull-in voltage. This index is used to determine the critical bound for the choice of the stiffness of the newly introduced compression member.
Effect of Carbon Nanotube on Electrical, Thermal and Mechanical Properties of Epoxy
Authors: Zhou Yuanxin , Wu Peixuan , Cheng Zhongyang , Dey Biddut Kanti , Jeelani Shaik
Published: May 2009

In this study, electrical, thermal and mechanical properties of multi-walled carbon nanotubes (CNTs) reinforced Epon 862 epoxy have been evaluated. Firstly, 0.1 wt%, 0.2 wt%, 0.3 wt%, and 0.4 wt% CNT were infused into epoxy through a high intensity ultrasonic liquid processor and then mixed with EpiCure curing agent W using a high speed mechanical agitator. The trapped air and reaction volatiles were removed from the mixture using a high vacuum. Neat epoxy sample also was made as reference. Electrical conductivity, dynamic mechanical analysis (DMA, three point bending tests and fracture tests were performed on unfilled, CNT-filled epoxy to identify the loading effect on the properties of composites. Experimental results show significant improvement in electric conductivity. The resistivity of epoxy decreased to 15Ωm with 0.4% CNT. DMA studies revealed that filling the carbon nanotube into epoxy can produce a 90% enhancement in storage modulus and a 17° C increase in Tg, but CNT has little effect on decomposing temperature. Mechanical test results showed that modulus increased with higher CNT loading percentages, but the 0.3 wt% CNT-infusion system showed the maximum strength and fracture toughness enhancement. The decrease in strength and fracture toughness in 0.4% CNT/epoxy was attributed to poor dispersions of nanotubes in the composite.
A Tunable Vibration Isolator Using a Magnetorheological Elastomer With a Field Induced Modulus Bias
Authors: Opie Saul , Yim Woosoon
Published: May 2009

Magnetorheological Elastomers (MRE) are composed of a ferromagnetic filler, micron sized iron particles, in an elastomer matrix. When a magnetic field is applied to an MRE, the iron particles develop a dipole interaction energy, which results in the material displaying a field dependent modulus. MRE materials have received attention in the last decade due in part to their potential application in semi-active vibration isolators. However, compared to MR fluid dampers, few applications of MRE materials have been developed, and no commercial devices are available. This paper describes the development of an MRE based isolator. Unique to this design is the introduction of a field induced modulus bias via a permanent magnet, which can be offset with a current input to the electromagnetic control coil. If the field bias is not significant enough to saturate the iron particles then an appropriately directed input current can also further increase the field induced modulus. Such a Biased Magnetorheological Elastomer (B-MRE) could be useful for applications where the designer wishes to decrease the system stiffness, something that has not been addressed by other MRE based devices.
Haptic Guided Rigid Body Dynamics Study for Virtual Assembly in Mainstream CAD Systems
Authors: Zhu Weihang
Published: May 2009

This paper presents our exploration in Haptic-guided Dynamics Simulation in a mainstream Computer-aided Design (CAD) System. Haptic interface, by providing force feedback in human-computer interaction, can improve the working efficiency of CAD/CAM (Computer-aided Design and Manufacturing) systems in a unique way. The full potential of the haptic technology is best realized when it is integrated effectively into the product development environment and process. For large manufacturing companies this means integration into a commercial CAD system [Stewart 1997]. Built on our past foundation work on an infrastructure of haptically enhanced CAD system [Zhu 2006], this research continues to explore the algorithms for dynamics simulation guided with haptic interface. This is fundamental to other tasks such as Virtual Assembly and Digital Mock-up. The research follows a modular haptic rendering algorithm for stable and transparent 6-DOF manipulation as presented in [Otaduy 2006], with improvements by leveraging the built-in CAD system functions and third party Dynamics Engines. The native CAD models are converted to triangulated meshes which are used in object-object collision detection and dynamics response computation. The major contribution of this paper is that we have developed a feasible methodology for haptic-guided dynamic interactions among CAD models inside mainstream CAD systems. It lays the foundation for future tasks such as direct CAD model modification and virtual assembly with the aid of haptic interface.
Automation Course With Direct Measures for ABET Outcomes Assessment
Authors: Gurocak Hakan
Published: May 2009

This paper presents an assessment system developed for ABET accreditation. The system links program outcomes to course outcomes through a set of performance criteria. In each course, direct measures are used to assess how well the course outcomes are met. Assessment data from each course is then mapped to the program level to measure achievement of the program outcomes. First, details of the assessment process are explained with applications of the process to an automation course. Then, a brief overview of the course and laboratory content are provided.
Dynamic Behavior of a Plate Under Air Blast Load Using Differential Quadrature Method
Authors: Tuna Murat , Turkmen Halit S.
Published: May 2009

The effect of blast load on the plate and shell structures has an important role on design decision. Blast load experiments are usually difficult and expensive. Therefore, numerical studies have been done on the response of blast loaded structures. However, because of time dependency of the nature of the problem, numerical solutions take long time and need heavy computational effort. The differential quadrature method (DQM) is a numerical solution technique for the rapid solution of linear and non-linear partial differential equations. It has been successfully applied to many engineering problems. The method has especially found application widely in structural analysis such as static and free vibration analysis of beams and plates. The capability of the method to produce highly accurate solutions with minimal computational efforts makes it of current interest. In this paper, the dynamic behavior of isotropic and laminated composite plates under air blast load has been investigated using the differential quadrature method. The results are compared to the numerical and experimental results found in the literature.
Modeling of Human Lower Extremity Musculo-Skeletal Structure Using Bond Graph Approach
Authors: Selk Ghafari Ali , Meghdari Ali , Vossoughi Gholam Reza
Published: May 2009

A vector bond graph approach for dynamic modeling of human musculo-skeletal system is addressed in this article. In the proposed model, human body is modeled as a ten-segment, nine degree of freedom, mechanical linkage, actuated by ten muscles in sagittal plane. The head, arm and torso (HAT) are modeled as a single rigid body. Interaction of the feet with the ground is modeled using a spring-damper unit placed under the sole of each foot. The path of each muscle is represented by a straight line. Each actuator is modeled as a three-element, Hill-type muscle in series with tendon. The governing equations of motion generated by the proposed method are equivalent to those developed with more traditional techniques. However the models can be more easily used in conjunction with control models of neuro-muscular function for the simulation of overall dynamic motor performance. In the proposed structure, segments can be easily added or removed. Such a model may have applications in clinical diagnosis and modeling of paraplegic patients during robotic-assisted walking.
An Innovative Method of Teaching: A Researched Survey-Based Term Assignment
Authors: Gharebaghi Maryam
Published: May 2009

The teaching process should be organized in such a way that learners can take responsibility for their own learning processes. Educational analysts often argue that one problem with classes, is that they are still dominated by the simple lecture format. Teaching innovations are defined as small changes in education that enable students to convert time to knowledge more quickly. In this paper, as an alternative, conduction of an innovative teaching method is introduced and demonstrated. The main findings of a research administrative questionnaire based survey conducted by students are presented. For the Building Service Systems course, junior architectural students are assigned to conduct a residential building survey and the analyzed results are considered as their term project grade. As the innovation in this method, students are asked to provide pictures to verify their answers. Each survey is double checked and accepted only when specific requirements are met. Some related diagrams and sketches are required as a proof that students understood the course material practically.
Macro and Nano Serially-Compounded Cantilevers for Resonance-Shift Mass Detection
Authors: Lobontiu Nicolae , Lupea Iulian , Ilic Rob
Published: May 2009

Detecting extraneous matter that deposits on a compliant receiver platform can be performed by means of the resonance shift method, whereby the original and altered natural frequencies of the host structure are compared to evaluate the amount and/or position of the attached matter. By scaling structural dimensions down to the nanometer range, it becomes possible to discern quantities in the molecular realm. One simple and convenient structural detector is the cantilever, whose out-of-the-plane resonant vibrations can be excited/monitored with relative ease. The proposed paper studies a few aspects of the mass attachment detection through monitoring of the natural frequency change of cantilevers, by focusing on the two ends of the dimensional spectrum: the macro- and nano-scale domains. The paper develops an analytical model that enables predicting the mass of attached matter in case its location is point-like and pre-specified. At nano-scale, locating mass attachment is realized through adequate surface functionalizing, while at macro-scale a displacement sensor can be placed conveniently on the compliant structure. The model accommodates cantilever configurations formed of several single-profile segments that are serially connected. Of all possible combinations, the two-segment, circularly-notched design is explicitly studied. Finite element simulation is utilized to check the analytical model validity. The bending natural frequencies of several macro-scale and nano-scale circularly-notched cantilever specimens have been investigated experimentally. Based on the agreement between analytical, numerical and experimental data, the analytical model was further utilized to study the relationships between geometric parameters, deposited mass, mass attachment position and the change in the bending resonant frequency.
Improvement of Impact Identification Capability of Time Reversal Processing Using Experimentally Measured Surface Bonded PZT Sensor Signals
Authors: Adachi Kazuhiko , Horiuchi Syota
Published: May 2009

In this study, the effect of time duration of the measured sensor signal to the impact identification capability of time reversal processing method is experimentally demonstrated. Time reversal processing for the measured sensor signal can be applied to detect not only structural damage but also impact loading of the structure. After measuring the electrical sensor signals corresponding to scattered wave filed of the plate experimentally, time reversal processing is applied to the measured signals in the numerical wave back propagation simulation for localizing the impact loading point on the plate. A time-reversed wave travels back through the plate and is focused on the region around a point where hits by the impact hammer. The illustrative experimental and numerical processes demonstrated the impact identification capability of time reversal processing method. Even if the measured signals were missing the wave front induced by the impact, the signal to noise ratio of the backward process was successfully improved by using the long time duration of the measured sensor signals.
Computer Simulation of Deep Drawing Process for a Laminated Composite Cup
Authors: Naik Tushar , Hu Zhong
Published: May 2009

The anisotropic nature of laminated composites creates a unique opportunity and also a great challenge for tailoring their behavior during the forming processes according to the design requirements. In this work, design and simulation of a deep drawing process for fiber-reinforced laminated composites were conducted by using finite element analysis. The effects of the fiber orientation and stacking order on the deep drawing process were investigated based on the basic understanding of forming process of the isotropic aluminum alloy (Al-1100) and laminated composite material (Grilon RVZ-15H nylon/glass). A three dimensional finite element model incorporating layered structural laminates with various fiber orientations was developed. The load-stroke relationship, changes in thickness, and stress-strain distribution were investigated and compared for both aluminum alloy and laminated composites of [0]12, [0/90]6 and [0/90/45/135]3, which can be employed for detailed design and process optimization.
Development of a Test Stand for the Characterization of Thermoelectric Modules for Power Generation
Authors: Smith Kevin , Sandoz-Rosado Emil , Jno-Charles Crisson , Henry Clement , Herrmann Erik , Stevens Robert J.
Published: May 2009

The characterization of thermoelectric modules for power generation applications has only received minimal attention by researchers. This paper describes the development of a test stand for the characterization of the thermoelectric power modules. The test stand has the ability to provide constant temperatures on the hot and cold side of thermoelectric modules and measure the amount of electrical power generated. Great care was taken to provide a uniform temperature on both the hot side and cold side of the module, with the hot side having the capability to provide temperatures of up to 600°C and the cold side able to be maintained at room temperature. The system is able to deliver a controlled heat flux of 140 kW/m2 to a thermoelectric module. A data acquisition system was developed to record the electrical performance of tested modules under a wide range of operating temperatures regulated by the control system. Using the collected data it will be possible to compare many modules and evaluate their performance with one another as well as provide module power generation parameters which can be useful for thermoelectric system design. This project was commissioned through the RIT Multidisciplinary Senior Design program as a capstone to the undergraduate degree curricula.
Effect of Dynamic Contact Angle on Single/Successive Droplet Impingement
Authors: Sangplung S. , Liburdy J. A.
Published: May 2009

Successive droplet impingement onto a solid surface is numerically investigated using a CFD multiphase flow model (VOF method). The main focus of this study is to better understand the hydrodynamics of the non-splash impingement process, particularly the effect of a dynamic contact angle and fluid properties along with the interaction between successive droplets while they are impinging onto a solid surface. The pre-impact droplet conditions are prescribed based on a spherical droplet diameter, velocity, and inter-droplet spacing. The molecular kinetic theory is used to model the dynamic contact angle as a function of a contact line velocity. The numerical scheme is validated against experiment results. In the impact spreading and receding processes, results are analyzed to determine the nondimensional deformation characteristics of both single and successive droplet impingements with the variation of fluid properties such as surface tension and dynamic viscosity. These characteristics include spreading ratio, spreading velocity, and a dynamic contact angle. The inclusion of a dynamic contact angle is shown to have a major effect on droplet spreading. In successive droplet impingement, the second drop causes a surge of spreading velocity and contact angle with an associate complex recirculating flow near the contact line after it initially impacts the preceding droplet when it is in an advancing condition. This interaction is less dramatic when the first drop is receding or stationary. The surface tension has the most effect on the maximum spreading radius in both single and successive droplet impingements. In contrast to this, the viscosity directly affects the damping of the spreading-receding process.
Numerical Analysis of a Planar Wave Propagation Based Micropropulsion System
Authors: Tabak A. F. , Yes¸ilyurt S.
Published: May 2009

Micropropulsion mechanisms differ from macro scale counterparts owing to the domination of viscous forces in microflows. In essence, propulsion mechanisms such as cilia and flagella of single celled organisms can be deemed as nature’s solution to a challenging problem, and taken as a basis for the design of an artificial micropropulsion system. In this paper we present numerical analysis of the flow due to oscillatory planar waves propagating on microstrips. The time-dependent three-dimensional flow due to moving boundaries of the strip is governed by incompressible Navier-Stokes equations in a moving coordinate system, which is modeled by means of an arbitrary Lagrangian-Eulerian formulation. The fluid medium surrounding the actuator boundaries is bounded by a channel, and neutral boundary conditions are used in the upstream and downstream. Effects of actuation parameters such as amplitude, excitation frequency, wavelength of the planar waves are demonstrated with numerical simulations that are carried out by third party software, COMSOL. Functional-dependencies with respect to the actuation parameters are obtained for the average velocity of the strip and the efficiency of the mechanism.
The Effects of Driving Waveform and Frequency on the Droplet Formation Process
Authors: Yang G. , Liburdy J. A.
Published: May 2009

For a piezoelectric stack (PZT) driven droplet generator, the driving waveform and driving frequency effects on liquid filament shape and droplet characteristics have been studied. A lumped element model (LEM) is developed to study the acoustic-mechanical behavior and the volumetric rejection of the droplet generator. Based on the LEM, the PZT displacement magnitude dominates the internal pressure variation within the chamber. However due to the natural response of droplet generator, the acoustic pressure in the droplet generator decays exponentially. Experimental data show that the droplet formation process can be waveform and frequency dependent. When the droplet formation process is driven in the “low frequency” regime, the droplet formation process is weakly affected by frequency. Meniscus interaction effects, which are the interaction of a liquid filament from different droplet generation cycles, on the droplet formation process will be present when the droplet formation process is driven in the “high frequency” regime. Due to meniscus interactions, the droplet formation process at “high frequency” is waveform and frequency dependent. Results show that the droplet volume reduces with driving frequency, and droplet velocity increases with driving frequency. However the droplet break-off time is only weakly affected by the driving frequency.
Study on Heat Transfer and Flow Analysis of 5×5 and 5×1 Mini-Tube Bank of Micro Heat Exchanger
Authors: Arai M. , Koizumi Y. , Ohtake H.
Published: May 2009

Heat transfer and flow behavior in the mini rod bank were examined. The tube bank was simulated with 5 wires of 1 mm diameter. The wires were arranged on the center line of the flow channel of 30 mm wide, 15 mm high and 300 mm long. The pitch between wires were varied from 1.5 mm to 9 mm. Experiments were performed in the range of the rod Re = 1 ∼ 400, i.e. the flow velocity in the channel was in the range of 0.0036 m/s ∼ 0.34 m/s. The measured heat transfer coefficients of the first row were a little bit higher than, rather close to, the predicted values by the correlations. The heat transfer coefficients after the second row were lower than those of the first row. The difference between those increased as the Reynolds number was increased. Around Reynolds number = 100, the difference turned to decrease. After the occurrence of the heat transfer coefficient recovery in the rows after the second row, the deeper the row was, the larger the heat transfer coefficient was. The flow visualization results and the analytical results by the STAR-CD code indicated that when the Reynolds number was low, the wake region of the preceding rod was stagnant. This flow stagnation caused the heat transfer coefficient deterioration around the stagnation point of the rear rod. As the Reynolds number was increased, the flow state in the wake region changed from the stagnant condition to the more disturbed condition by periodical shedding of the Karman vortex from the preceding rod. This agitation of the wake region by the vortices caused the recovery of the deteriorated heat transfer coefficients. The deeper the row was, the more disturbed the wake flow state was. The measured average heat transfer coefficients of the tube bank agreed well with the analytical results by the STAR-CD code. The measured and the analyzed results were close to the predicted values by correlations.
An Artificial Neural Network Approach to Payload Estimation in Four Wheel Drive Loaders
Authors: Hindman Jahmy , Burton Richard , Schoenau Greg
Published: May 2009

Estimation of the manipulated payload mass in off-highway machines is made non-trivial by the nonlinearities associated with the hydraulic systems used to actuate the linkage of the machine in addition to the nonlinearity of the kinematics of the linkage itself. Hydraulic cylinder friction, hydraulic conduit compressibility, linkage machining variation and linkage joint friction all make this a complex task under even ideal (machine static) conditions. This problem is made even more difficult when the linkage is mobile as is often the case with off-highway equipment such as four-wheel-drive loaders, cranes, and excavators. The rigid body motion of this type of equipment affects the gravitational loads seen in the linkage and impacts the payload estimate. The commercially available state-of-the-art load estimation solutions rely on the mobile machine becoming pseudo-static in order to maintain accuracy. This requirement increases the time required to move the material and decreases the productivity of the machine. An artificial neural network solution to this problem that enables the machine to remain dynamic and still accurately estimate the payload is discussed in this paper. Development and implementation on an actual four-wheel-drive loader is shown.
Simulation of Blast-Head Interactions to Study Traumatic Brain Injury
Authors: Sotudeh Chafi M. , Karami G. , Ziejewski M.
Published: May 2009

This paper presents a methodology for predicting the mechanical damage inflicted on the brain by a high explosive (HE) detonation and leading to traumatic brain injury (TBI). A brain model, with its complexity, is used in the computational procedure. The processes of HE detonation and shock propagation in the air, as well as their interaction with the head, are modeled by an Arbitrary Lagrangian Eulerian (ALE) multi-material formulation, together with a penalty-based fluid/structure interaction algorithm. This methodology provides intracranial pressure and maximum shear stress within the microscale time frame for this highly dynamic phenomenon. Two scenarios are simulated. In one scenario, the brain is in close proximity to a 1lb trinitrotoluene (TNT) explosion, and the other to a 0.5lb explosion. The resulting countercoup intracranial pressure-time histories, from the 1 lb TNT explosive scenario, demonstrates that pressure falls below −100 kPa. This can cause cavitation bubbles and damage to the brain tissue. The simulations also predict that the areas of high pressure and shear stress concentration are consistent with those of clinical observations. These resulted intracranial pressure and shear stress responses are the parameters to examine against injury criterions thresholds.
Posture Synthesis and Control of a Symmetric Hexapod Robot on Corrugated Surfaces for Underwater Observation
Authors: Wu Xin , Li Yaoyu , Consi Thomas R.
Published: May 2009

This paper presents the first stage of a project to develop a six-legged walker (hexapod) as a highly stable mobile sensor platform for in situ benthic observation. The hexapod is radially symmetric with a downward looking, CCD camera-coupled, microscope mounted co-linear with the central axis of the body. A Lynxmotion (Peoria, IL) Model EH-3R radially symmetric 18 degrees-of-freedom hexapod robot has been used for initial land-based experiments and simplified to a 12 degree-of-freedom structure by locking the panning joint of each leg. Forward and inverse kinematics are then used to derive the relationship between the body posture and the proximal and distal joint angles on legs, which is the basis of the microscope’s coarse focusing for the observation. The kinematics analysis has been verified with both Matlab-based simulations and experiments on the hexapod prototype. Finally, passivity-based posture control is developed and simulated based on the inverse dynamics of the robotic leg.
Submicron-Scale Flexible Ribbon Cable Seek-Settling Induced Vibration Reduction in High Capacity Disk Drives
Authors: Chang J. Y.
Published: May 2009

This paper presents a modeling and design methodology to reduce and even to eliminate flexible ribbon cable seek-settling induced vibrations in modern high capacity computer disk drives. Optimization is first conducted in obtaining proper cable profiles when the rotary actuator swings across the disk using classical elastica theory with consideration of compliant boundary at its J-block conjunction point with rotary actuator and fixed boundary conditions at bracket. In addition to modal kinetic coupling factor, the cable’s vibration modes are projected onto actuator voice coil’s excitations to form as a weighted response factor to serve as the cost function in optimization process. It was found through the proposed process that the seek-settling flexible cable vibration can be minimized and even reduced to zero. Additional servo adaptive control format will be also discussed in this paper to totally eliminate the flexible ribbon vibrations in disk drive’s seek-settling operations.
Finite Element Study of a Micro-Opto-XRay Imaging Lens for Biomedical Applications
Authors: Ostadi H. , Arroyo Marino , Prewett P. D. , Huq S. E.
Published: May 2009

Micro-Electro-Opto-Mechanical-Systems or MOEMS have potential applications inter alia in biomedical research. For instance, studies of the Bystander Effect require controlled irradiation of biological cells with focused X-rays to reveal the mechanisms occurring. X-ray focusing may be achieved using an adaptive optic micro-lens in which focusing is entirely reflective and therefore compatible with broad band illumination, an improvement over diffractive systems such as zone plates. Such a micro-lens can be microfabricated in the form of a bent-cantilever beam made from two dissimilar materials (polyimide and gold) in a thermal bimorph configuration, actuated with a micro heater. The parallel horizontal slots on the beam provide the transmission and focusing functions, while the heater provides control of the focal length through variation of the beam’s curvature. This novel system has been named 1D-MOXI (Micro-Opto-X-ray Imaging) and a basic system has already been made and tested thermo-mechanically. The present paper focuses on details of the geometry of the deformed slotted micro-beam lens element under thermally derived strain, using finite element analysis, and suggests an optimized MOEMS design, giving prescribed curvature of the lens through changing the number and the dimensions of the slots. The study reveals the localized stress and the small deviations of the micro-lens behavior from that of perfect spherical geometry. The focal length variation with temperature is compared with the experimental values and those predicted by an analytical model.
In-Process Detection of Fastener Grip Length Using Embedded Mobile Wireless Sensor Networks
Authors: Anguswamy Reghu , Saygin Can , Sarangapani Jagannathan
Published: May 2009

In this paper, a diagnostics and root-cause analysis scheme for real-time monitoring of process quality of pull-type fastening operations is presented. The proposed approach encompasses (1) integrating a strain gage, an LVDT (Linear Variable Differential Transducer), a pressure sensor, and a mote on a pull-type pneumatic tool; (2) monitoring process parameters coming from embedded sensors communicated wirelessly via the mote and generating process signatures in real-time; and (3) detecting anomalies in real-time in the process signatures for quality problems related to the grip length deviation in pull-type fastening operations. A feature extraction-based diagnostic methodology is employed to make decisions in terms of grip length deviations in the form of normal grip, over grip, and under grip. The process signature of strain-over-displacement versus displacement has shown unique features that are extracted to determine the quality of the fastening process. In addition, air pressure is also continuously monitored in real-time during the process since it also affects the quality of the fastening operation. The overall architecture has been implemented on a Huck45 pull-type tool, which is a hand-held pneumatic fastening tool used extensively in the aerospace industry, with lock-bolt fasteners. The prototype has been tested under a variety of experimental settings in order to verify its effectiveness and validate its performance over a wide range of different sheet metal thicknesses used for fastening. The experiments have shown that the proposed approach is successful, with an accuracy of over 96%, in determining the quality of fastening operations and in communicating the quality information in real-time using a wireless network to a server. Overall, the proposed architecture has merits to (1) detect quality problems in real-time during the fastening process and (2) reduce post-process inspection, thereby improving quality while reducing cost. In addition, the proposed approach facilitates 100% data collection on each fastener as opposed to traditional statistical process control (SPC) techniques, which rely on sampling.
Investigation of a High Precision Hydrostatic Actuation System: How Nonlinearities Affect Its Performance
Authors: Li Wei , Burton Richard , Habibi Saeid
Published: May 2009

A prototype Electro-Hydraulic Actuator (EHA) system has demonstrated a positional accuracy in the order of 100 nanometer. Linearized models of the EHA have been formulated and have shown reasonable correlation to the performance of the physical EHA. However, these models predict zero steady state error (an impossible situation given the physical limitations of seals, friction etc.). Further, the prototype EHA indicates that the cut-off frequency decreases as the amplitude of the input signal decreases. This is not predicted by the linear models. In this paper the Bond-graph large scale modeling technique was used as the basis to formulate the describing equations of the EHA. The model was made increasingly more complex by introducing observable nonlinearities into the model. It was found that the introduction of nonlinear friction did show results whose trends were consistent with those observed experimentally. Assumed nonlinearities in the bulk modulus could not be substantiated. In addition, some of the observed experimental trends could not be predicted (such as order change) and pose additional challenges to be solved before a complete understanding of the true physics of the EHA can be realized.
Applying the Generalized Stefan-Maxwell Equations to Ion and Water Transport in the Polymer Electrolyte of a PEM Fuel Cell
Authors: Baschuk J. , Li Xianguo
Published: May 2009

Ion and water transport phenomena in the polymer electrolyte plays a significant role in the energy conversion process of a polymer electrolyte membrane (PEM) fuel cell. A mathematical model for ion and water transport in the polymer electrolyte is presented, based on non-equilibrium thermodynamics and the Generalized Stefan-Maxwell equations. The physical constants of the model, such as the binary diffusion coefficients of the Generalized Stefan-Maxwell equations, are obtained from published, experimental data for membrane water diffusion and conductivity. The electrolyte transport model is incorporated into a model of an entire PEM fuel cell; water transport in the electrolyte and gas phase are coupled and solved in a single domain.
Mathematical Modeling of Pulsation Dampeners in Fluid Power Systems
Authors: Duan Shanzhong , Gamal Mutasim E.
Published: May 2009

This paper presents a new method for computer-aided modeling and analyzing of pulsation dampeners used in fluid power systems for vibration reduction. The pulsation dampeners are widely used in various fluid power systems to reduce vibration induced by power pumps. The vibration induced by power pumps in fluid systems may be severe enough to cause the damage of components in pipelines if a pulsation dampener is not installed. However, the current methods used in industries for the design and analysis of the dampeners are manually experience-orientated procedures. They are not adaptable to new technologies. The new modeling method will efficiently automate and improve the current modeling and analysis procedure of various pulsation dampeners with a minimum user effort. The proposed method is a result of utilizing the analogy between electrical circuits and hydraulic circuits. In the new method, a spherical pulsation dampener can be equivalent to a lumped hydraulic circuit installed in a distributed fluid pipeline system. The new method has been developed from the authors’ previous work of an impedance-based model in which only the effect of capacitance and inductance was considered without fluid resistance. In reality, the influence of fluid resistance is significant. This paper will take fluid resistance into considerations and form a resistance-impedance-based model.
Unsteady Pressures on the Surface of a Ship Hull
Authors: Goody Michael , Farabee Theodore , Lee Yu-Tai
Published: May 2009

The unsteady surface pressures caused by turbulent boundary layer flow are a source of sound and vibration. Unsteady surface pressure measurements at locations distributed on the surface of a ship model hull were carried out in order to characterize this source. The pressure measurement locations were distributed over the hull surface from 15% to 70% of the model length. There were several additional pressure measurement locations on the hull surface adjacent to the bow wave. The measurements were performed in the David Taylor Model Basin. The surface pressure spectra collapse to a single curve when scaled by canonical boundary layer variables at measurement locations aft of the bow wave. Additionally, measurements at several of these locations indicate that the pressure sources are convected at 50% to 80% of the free-stream velocity. Both of these observations are similar to equilibrium turbulent boundary layers. The measured surface pressure spectra compare well to predictions done using an empirical model that is based on historical, equilibrium, surface pressure spectra. At low frequencies, the measured surface pressure spectra also compare well to prediction done at lower Reynolds number using a Reynolds-Averged Navier-Stokes Statistical Model.
Transient Numerical Modeling of Catalytic Channels
Authors: Struk P. M. , Dietrich D. L. , Miller F. J. , T’ien J. S.
Published: May 2009

This paper presents a transient model of catalytic combustion suitable for isolated channels and monolith reactors. The model is a “lumped” two-phase (gas and solid) model where the gas phase is quasi-steady relative to the transient solid. Axial diffusion is neglected in the gas phase; lateral diffusion, however, is accounted for using transfer coefficients. The solid phase includes axial heat conduction and external heat loss due to convection and radiation. The combustion process utilizes detailed gas and surface reaction models. The gas-phase model becomes a system of stiff ordinary differential equations while the solid phase reduces, after discretization, into a system of stiff ordinary differential-algebraic equations. The time evolution of the system came from alternating integrations of the quasi-steady gas and transient solid. This work outlines the numerical model and presents some sensitivity studies on important parameters including internal transfer coefficients, catalytic surface site density, and external heat-loss (if applicable). The model is compared to two experiments using CO fuel: (1) steady-state conversion through an isothermal platinum (Pt) tube and (2) transient propagation of a catalytic reaction inside a small Pt tube. The model requires internal mass-transfer resistance to match the experiments at lower residence times. Under mass-transport limited conditions, the model reasonably predicted exit conversion using global mass-transfer coefficients. Near light-off, the model results did not match the experiment precisely even after adjustment of mass-transfer coefficients. Agreement improved for the first case after adjusting the surface kinetics such that the net rate of CO adsorption increased compared to O2. The CO / O2 surface mechanism came from a sub-set of reactions in a popular CH4 / O2 mechanism. For the second case, predictions improved for lean conditions with increased external heat loss or adjustment of the kinetics as in the first case. Finally, the results show that different initial surface-species distribution leads to different steady-states under certain conditions. These results demonstrate the utility of a lumped two-phase model of a transient catalytic combustor with detailed chemistry.
Analysis of the Grasp Planning Method for Manipulation of BH-4 Dextrous Hand
Authors: Guo Weidong , Tomovic Mileta M. , Li Jiting
Published: May 2009

The paper presents method for planning robotic dexterous hand grasping task using example of the Beihang University’s BH-4 dexterous hand. The grasping planning method is devised through modeling and simulation and experimentally verified using physical prototype. The paper presents the method for forward and inverse kinematic solutions of the BH-4 robot 4-DOF finger, including transformation matrix between the palm coordinate system and the finger base coordinate system. In addition, the method of the idiographic manipulation is presented using example of ball grasping. The simulation results and physical experiment verify that the inverse kinematic solution is correct, and kinematic grasping and operating planning is valid and feasible. Finally, the experiment with the complex system integrated robot arm with dexterous hand is carried out. Experimental result shows that the more complicated grasping task can be done by a dexterous hand integrated in the robot arm system.
Evaluation Method of Design Products Based on Eco-Efficiency
Authors: Oizumi Kazuya , Tokuoka Naochika
Published: May 2009

Evaluation methods of Environmental burdens have been improved. Some of those methods indicate intensity of environmental burdens in money unit to make them comparable to production cost. Moreover, from sustainability point of view, improvement of functions is as important as reduction of environmental burdens. Namely, environmental burdens and functions have to be balanced. Therefore, we aimed to develop the evaluation method of design products that is able to optimize balance between them. We had developed the evaluation method of environmental burdens, which indicates potential of economical loss caused by environmental impacts and defined it as Societal Cost. This is used for evaluation of environmental burden. In this paper, we improve this method by adding the Function Value. To compare the value of functions with environmental burdens, every evaluation criterion has to be integrated in single score, and it is desired to be money unit. We derived value of functions by using the information theory and defined it as Function Value. Eco-Efficiency Index evaluates products. This is based on the concept of Eco-Efficiency and calculated by dividing Function Value by Societal Cost. Societal Cost: Pollutants cause many environmental impacts and many kinds of losses through their lifetimes, and most of them can not be converted into money except the loss of productivity. Societal Cost indicates the social loss of productivity by the decrease of human health caused by the increase of disease or disaster originates on emission of pollutants. Function Value: To evaluate products’ value in single score, value of each functions existing in product has to be quantified and integrated. The information theory is applied for this method. Amount of information of each function is derived from probability of satisfying consumer. However, functions have different importance. Therefore, amounts of information of functions are added up after weighted by Relative Importance of each function, which is determined by using QFDE. We defined it as Integrated Amount of Information. It is also important to think the span of utilization. To express the relation between product’s value and time in use, three types of depreciation methods are applied. They should be chosen in accordance with aging characteristics of product. Eco-Efficiency Index: Eco-Efficiency Index is defined as Function Value divided by Societal Cost. This definition is based on the concept of Eco-Efficiency advocated world wide, which mean obtained value per unit amount of environmental burden.