bluuebunny/crossref_metadata_2025 huggingface dataset:
A New Kinematic Kalman Filter (KKF) for End-Effector Sensing of Robotic Manipulators
Authors: Jeon Soo , Tomizuka Masayoshi , Katou Tetsuaki
Published: May 2009

The kinematic Kalman filter (KKF) is a sensor-based state estimator which is immune to the external disturbances and the parameter uncertainties of mechanical plants. This paper extends the original idea of the KKF to a more general form as a means to enhance a real time vision sensor for the end-effector control of a robot manipulator, the performance of which is often limited by its slow sampling rate. The original one-dimensional KKF is reformulated in a higher dimensional form by incorporating the measurements from the vision sensor, accelerometers and gyroscopes. A nonlinear state space model of the kinematics of the end-effector is derived including the time delay associated with vision sensing. Then, the new KKF is formulated as a state estimator combining the inter-sample predictions with an extended Kalman filter (EKF). The paper discusses practical issues such as the real time computation to implement the EKF and the vision sensor to measure the absolute position. Experimental results are presented to confirm the benefits of the new KKF using a two-link direct drive manipulator equipped with a dual axis MEMS accelerometer, a single axis MEMS gyroscope and an end-effector mounted vision camera. The accurate estimation of the position and velocity of the end-effector from the new KKF will be useful for the real time visual-servo and the task space control of robot manipulators.
Air Conditioning Waste Heat to Domestic Hot Water: A Student Design Project
Authors: Yilmaz Emin
Published: May 2009

The goal of the “Domestic Hot Water Heater Using Air Conditioner (A/C) Waste Heat” design project was to introduce students to designing mechanical systems in the “ETME475-Mechanical Systems Design” course. The design project was assigned to two Mechanical Engineering Technology students as their second design project in the course. Students were asked to do their own literature search and create their own designs. Both of them decided to use a concentric-tube heat exchanger to extract heat from hot refrigerant gas to heat water residing in domestic hot water heater tank. Their literature search led them to some manufacturers. Since delivery time for concentric-tube heat exchanger was too long, we purchased a side-by-side-tube heat exchanger and got it installed on our Heat Pump. Some test runs were conducted to measure the efficiency of the unit and its effect on the Coefficient of Performance (COP) of the Heat Pump when heat pump is operated in A/C mode. Contrary to our expectations, results indicate that, COP values have been reduced by about 22%. Measured efficiency of the unit was about 18%. Students have designed a concentric-tube heat exchanger, turned in their final reports and orally presented their designs to the class.
Modeling of the Axial and Tilt Stiffness Between a Magnet Track and a Ferromagnetic Backing
Authors: Krishnasamy Jay , Moura Jairo
Published: May 2009

This paper consists of modeling and analysis of the axial and radial forces as well as axial and tilt stiffness between a magnetic track and a ferromagnetic backing. The proposed model utilizes the concept of Maxwell stress tensor and simplified reluctance models in order to predict the magnetic interactions between the rotor and the stator. In other to verify the model developed, finite element models and experiments are performed for the case of a linear magnetic track. The results can be applied to the case of rotary tracks without loss of generality. Applications of this work can be used in the design of magnetic bearings or servo motors with ferromagnetic stators.
Observer Design for a Steam Reformer Based Solid Oxide Fuel Cell System With Anode Recirculation
Authors: Das Tuhin , Mukherjee Ranjan
Published: May 2009

In this paper we design an observer for online estimation of species concentrations in a steam reformer based Solid Oxide Fuel Cell (SOFC) system with anode recirculation and with methane as fuel. Since in SOFCs steam reforming occurs both in the reformer and in the fuel cell, a large number of concentration sensors are necessary for accurate control of critical performance variables such as utilization and steam-to-carbon-ratio. The purpose of the observer is to reduce the number of sensors required for control. In contrast to existing observers which are either designed for chemical reactors or for fuel cells exclusively, our design considers the coupled dynamics of the reformer and the fuel cell. We design an adaptive observer where the rates of reforming reactions are treated as slowly varying unknown parameters. Using a few concentration sensors we show that all other species concentrations, molar flow rates, and reaction rates in the fuel path can be dynamically estimated. Simulation results are provided in support of the proposed design.
Design of Controllers for a Multi-Degree-of-Freedom Spherical Wheel Motor
Authors: Son Hungsun , Lee Kok-Meng
Published: May 2009

This paper presents the control system design for a particular form of variable-reluctance spherical motors, referred to here as a spherical wheel motor (SWM). Unlike most of the existing spherical motors where focuses have been on the control of the three-DOF angular displacement, the SWM offers a means to control the orientation of a continuously rotating shaft. Specifically, we demonstrate an effective method to decouple the open-loop (OL) control of the spin rate from that of the inclination, leading to a practical OL system combining a switching (spin-rate) controller and a model-based inclination controller. The OL system presented here provides the fundamental control structure for the SWM. To account for unmodeled external torques, we extend the design to allow feedback with a PD controller and a high-gain observer. The effectiveness of the controllers has been investigated by comparing their performance numerically under the influence of an unknown external torque.
Effects of a Lumbar Belt on Neuromotor Transmission of Whole Body Vibration
Authors: Abraham P. M. , Wilson S. E.
Published: May 2009

Whole body vibration (WBV) has been identified as a risk factor for low back musculoskeletal disorders and injuries. One potential mechanism by which WBV may lead to low back injury is through stimulation of muscle spindle organs and repetitive activation of the stretch-reflex neuromotor response. Such repetitive activation could lead to muscular fatigue and/or neuromotor adaptation. Understanding mechanical transmission of vibration to the neuromotor system and the resulting neuromotor activation is critical to understanding these mechanisms. In this study, it was theorized that activation of the extensor musculature of the low back is a response to the lengthening and shortening of the extensor musculature. This lengthening and shortening of the extensor musculature may be the result of flexion-extension rotation in the lumbar spine. By measuring lumbar flexion and extension, the amplitude and phase of this lengthening and shortening were assessed. Using electromyographic data from the erector spinae muscle groups at the L2/L3 lumbar level, the cyclic activation of the extensor musculature was also measured. Neuromotor transmission was observed over a frequency range of 3–20 Hz and vibration magnitudes of 1 and 2 m/s^2 RMS. Resonance peaks in lumbar flexion-extension and the integrated electromyographic data were observed at 4 Hz and 10–12 Hz. A lumbar belt was used to reduce transmission of axial seat-pan vibration to lumbar flexion-extension and to observe the changes in cyclic electromyographic activity. The lumbar belt was found to decrease both lumbar flexion-extension and paraspinal muscle activity demonstrating a link between axial seatpan vibration, lumbar flexion-extension and the cyclic activation of the neuromotor system. These results provide information on the neuromotor effects of WBV and may be used to design better low back injury prevention methods.
Label-Free and Immobilization-Free Immunoassay
Authors: Pinnick Island , Oh Kieseok , Chang Chen-Ling , Lee Kyong-Hoon , Chung Jae-Hyun
Published: May 2009

This paper presents an immunoassay capable of detecting an antigen without labeling or immobilization. By measuring a change in fluid resistance, the immunoassay successfully differentiates a positive control from a negative control. The same device can also act as a particle counter due to its high sensitivity. It is capable of detecting differences in concentrations as low as 104 particles per milliliter. An analytical model is developed to analyze the measured signal.
Initial Experiments on the Control of a Mobile Tower Crane
Authors: Vaughan Joshua , Singhose William , Debenest Paulo , Fukushima Edwardo , Hirose Shigeo
Published: May 2009

Cranes are used extensively throughout the world in a wide variety of construction and material handling applications. The speed at which these cranes are operated is limited by payload oscillation. Input shaping is one method that reduces this oscillation, allowing higher speeds and improving operational efficiency. Another method to improve the operational capabilities of cranes is to allow base motion. This paper presents initial experimental results from a portable, mobile tower crane. A theoretical model of the crane is presented and experimentally verified. The oscillatory dynamics of the crane are highlighted and controllers to combat these unwanted dynamics are presented.
A Methodology for Kinematics and Dynamics Analysis of Robotic Systems Internal Actuation
Authors: Deshpande Ashish D. , Luntz Jonathan E.
Published: May 2009

Robots with internal actuation and un-actuated environmental contacts form an important class of robotic systems that includes walking and climbing robots. Since actuation for motion in these robots is achieved indirectly the design and analysis present interesting challenges. In this paper we extend our previously described method called the P-robot Method and apply it to analyze internally actuated robotic systems. We illustrate our techniques by using a simple example of a ladder resting against a wall. Our techniques determine the conditions under which the ladder holds its position against the wall quasi-statically while satisfying the friction constraints and also determine the effects of ladder dynamics on the constraints. These techniques can be extended to analyze more complex systems such as walking and climbing robots and also to human motion modeling.
Homogenization and Equivalent In-Plane Properties of Hexagonal and Re-Entrant Honeycombs
Authors: Gonella Stefano , Ruzzene Massimo
Published: May 2009

The investigation of equivalent in-plane properties for hexagonal and re-entrant (auxetic) lattices can be carried out through the analysis of the partial differential equations associated with their homogenized continuum models. A homogenization technique is adopted based on the approximation of the discrete lattice equations according to the finite differences formalism. The technique can be used in conjunction with a finite element (FE) description of the lattice unit cell and therefore allows handling structures with different levels of complexity and various internal geometries within a general and compact framework that can be easily implemented in a numerical code. The in-plane wave propagation characteristics of honeycombs can be investigated with the proposed approach: approximate phase velocities can be calculated from the equations of motion for the low-frequency modes and compared with the exact values obtained through a Fourier analysis of the unit cell.
3-D Computational Fluid Dynamic Analysis of Bustle Gas Combustion in a Direct Reduced Iron Plant
Authors: Walker William , Farhadi Ali , Tsvik George , Roesel Tom , Selvarasu Naresh K. , Siow Yeow , Zhou Chenn Q.
Published: May 2009

Gases from a natural gas reformer are used to reduce iron oxides to iron in the direct reduced iron (DRI) plant. The reducing gases consist of mainly hydrogen and carbon monoxide and traces of methane, water vapor, carbon dioxide and nitrogen. Part of this gas mixture is burned to heat the gases to 1000°C (1832°F) by the injection of pure oxygen through an Inconel nozzle. The oxygen nozzle fails frequently, mainly due to the high temperature reactions. This paper aims to study the reactions that contribute to the high temperature for different oxygen flow rates and thus optimize the flow rates to prevent failure of the nozzle using a three dimensional (3D) computational fluid dynamics (CFD) model.
Numerical Simulation of Optical Trap Systems
Authors: Muddu Radha , Wereley Steve
Published: May 2009

The current work deals with numerical simulation of optical trap systems at time scales varying from very small to very large. This analysis is important to understand the effects of different forces acting on the optically trapped particle. The significance of inertia forces are also evaluated at these time scales. A novel method of computing diffusion coefficient from the simulated values is proposed. It has been shown that the computed values of the diffusion coefficient are an exact match to the theoretical results.
Sensitivity of Relative Worth in QFD Matrices to Rating Scales and Worth Calculation Schemes: An Empirical Study
Authors: Kalapurackal Robins M. , Takai Shun
Published: May 2009

In the past several decades, Quality Function Deployment (QFD) has gained its popularity among engineers as a tool to relate (map) customer requirements (inputs) to system requirements or system components (outputs), and to calculate relative worth of these requirements and components. The benefits of QFD in system development include cost reduction, fewer design changes after the start of production, and improved communication among engineers. Despite the observed benefits, the needs for QFD research have been addressed by researchers. These research needs include decision-making process in QFD, rating scales used in QFD matrices, and calculation schemes for calculating the worth of outputs (e.g., system requirements) from the importance of inputs (e.g., customer requirements). The purpose of this paper is to empirically study sensitivity of the relative worth and rank of outputs in QFD matrices to rating scales and worth calculation schemes. We collected QFD matrices from journal articles and textbooks; then calculated the changes of relative worth and the rank of outputs when one type of rating scale and/or worth calculation scheme was changed to the other. The results suggest that the relative worth and rank of outputs are relatively insensitive to rating scales and worth calculation schemes in the QFD matrices studied in this paper.
Capture of Very Rare Circulating Tumor Cells for Human Breast Cancer Diagnosis
Authors: Park Taehyun , Jensen Timothy , Park Daniel , Guy Jason , Datta Proyag , Soper Steven A. , Murphy Michael C.
Published: May 2009

A method of collecting and delivering single or precise numbers of cells to assess the feasibility of capturing very rare circulating tumor cells for human breast cancer diagnosis and monitoring was developed. A PMMA device was assembled with minimal assembly variation using passive alignment. Thermoplastic fusion bonding was optimized to yield minimal deformation of the microfluidic channel. UV modification and an anti-epithelial cell adhesion molecule (anti-EpCAM) functionalization process were used to generate capture surfaces and maximized by control experiment. Single or precise numbers of target cells were collected using a cell collecting capillary tube and a hemacytometer and delivered into the microchannel without any loss. Cells from one of the human breast cancer cell lines, the MCF-7 cell line (ATCC, Manassas, VA) which strongly overexpresses EpCAM, were successfully captured on the anti-EpCAM coated microchannel surfaces. Successful capture of early stage breast cancer cells in whole blood may be feasible with further optimization of the microchannel geometry and flow velocity through the microfluidic device.
Swarm Manipulation of a Disabled Vessel: Elimination of Velocity Measurements
Authors: Feemster Matthew
Published: May 2009

In this paper, an observer/controller strategy is developed for a swarm of autonomous tugboats with the collaborative mission of manipulating a disabled surface marine vessel into a desired position and orientation. Specifically, this design focuses on the elimination of direct velocity measurements/calculations during implementation by the formulation of a model based nonlinear observer. The tracking control algorithm is based on the measured tracking error signal as opposed to an estimated tracking error signal in an effort to provide improved performance.
CFD Analysis of Batch-Type Reheating Furnace
Authors: Wu Bin , Arnold Andrew M. , Arnold Eugene , Downey George , Zhou Chenn Q.
Published: May 2009

In the steelmaking industry, reheating furnaces are used to heat the billets or blooms to the rolling temperature; the uniformity of the temperature in the furnace determines billet quality. In order to obtain a better understanding of the furnace operation, which influences the temperature distribution; Computational Fluid Dynamics (CFD) analysis is conducted to examine the transient and three dimensional temperature fields in a reheating furnace using the commercial software Fluent®. A number of actual operating conditions, based on the ArcelorMittal Steelton No.3 reheating furnace, are computed. The numerical results are used to optimize the operating parameters and thus help to improve the steel quality.
A Sharp Surface Tension Modeling Method for Capillarity-Dominant Two-Phase Incompressible Flows
Authors: Wang Zhaoyuan , Tong Albert Y.
Published: May 2009

A surface tension implementation algorithm for two-phase incompressible interfacial flows is presented in this study. The surface tension effect is treated as a jump condition at the interface and incorporated into the Navier-Stokes equation via a capillary pressure gradient. The interface is tracked by a coupled level set and volume-of-fluid (CLSVOF) method based on the finite-volume formulation on a fixed Eulerian grid. It has been shown in a stationary benchmark test the spurious currents are greatly reduced and the sharp pressure jump across the interface is well preserved. Numerical instabilities caused by the sharp treatment on a fixed grid are avoided. Several dynamic tests are performed to further validate the accuracy and versatility of the present method, the results of which are in good agreement with data reported in the literature.
CFD Modeling of Bayonet Type High Temperature Heat Exchanger and Chemical Decomposer With Different Packed Bed Designs
Authors: Nagarajan Vijaisri , Ponyavin Valery , Chen Yitung , Vernon Milton E. , Pickard Paul , Hechanova Anthony
Published: May 2009

The present work is concerned with use of bayonet type high temperature heat exchanger as silicon carbide integrated decomposer (SID) which produces sulfuric acid decomposition product - sulfur dioxide. The product can be used within the sulfur iodine thermo-chemical cycle portion of the hydrogen production process. The chemical decomposition occurs in packed bed area of the decomposer. The engineering design of the packed bed is very much influenced by the structure of the packing matrix, which is governed by the shape, dimensions and the loading of the constituent particles. Optimum design of catalyst pellet in terms of shape configuration, packing method and available surface area can promote catalytic activity and the prevailing transport properties of the system. Knowledge of the underlying factors should enable designers to engineer the optimum design for a given system with prescribed conditions. The investigations of fluid flow and the arrangement of cylindrical and spherical pellets in packed bed are presented in the paper.
Parallel Force Measurement in Cell Arrays
Authors: Sasoglu F. Mert , Kilinc Devrim , Allen Kathleen , Layton Bradley
Published: May 2009

The primary goal of this work is to establish a robust, repeatable method for growing forebrain nerve cells in a parallel manner by stretching them using a microfabricated PDMS beam array and printing arrays of neurons. The highly compliant, transparent, biocompatible PDMS micro beam array may offer a method for more rapid throughput in cell and protein mechanics force measurement experiments with sensitivities necessary for highly compliant structures such as axons. This work has two endpoints. One is to use a neural array as an experimental testbed for investigating neuronal cell growth hypotheses. The other endpoint is to build a neuronal-based, biosensor device capable of acting as a cell-based sensor. We present preliminary results for microbeams attaching to nerve cells. The attachment ratio the life-length and the axon lengths of the chick forebrain cells on microprinted spots will also be compared with an equivalent protein coated area of cells.
Magnetic Flux Leakage Sensing: Current Practices and Mathematical Analysis
Authors: Dutta Sushant M. , Ghorbel Fathi H.
Published: May 2009

In this paper, we analyze magnetic flux leakage (MFL) sensing for the nondestructive evaluation (NDE) of ferromagnetic specimens. Understanding the processes involved in the creation of magnetic flux leakage fields and their measurement is critical to robotic inspection applications. In particular, robotic inspection of energy pipelines uses mobile robots to magnetize sections of the pipe and to measure the MFL signal to detect defects. We study current practices and motivate the need for improvements. To facilitate the analysis, we develop an analytical model to represent the 3-dimensional magnetic flux leakage field due to a surface-breaking defect in the specimen. The model is derived from first principles using the concept of dipole magnetic charge, and uses surface integrals to represent the MFL field as measured by a Hall-effect sensor. Simulations are performed which generate novel results, apart from reproducing experimental results from the literature. The mathematical tractability of the model is exploited to analyze its properties, such as scale–invariance, influence of lift-off, and the tangential MFL component. These properties give new insight into MFL sensing, interpretation, and defect characterization.
Preliminary Mechanical Analysis for Novel Woven/Wound Composite Axial-Compressor
Authors: Lahiri A. , Lindberg B. , Mu¨ller N.
Published: May 2009

This paper introduces an impeller design for a turbo compressor based on a novel composite material winding technology. The main objective is to develop a high performance impeller, which can be economically produced for refrigeration plants using water as a refrigerant (R718) even below 300 kW (100 ton) capacity. Water as a refrigerant can provide a very high coefficient of performance, while it is environmentally inert and hence preferred. The impeller is required to be able to handle large volume flows and also withstand high stresses due to high speed rotation for high compression ratios. Here, an impeller suitable for a counter rotating axial or mixed flow impeller is presented. Carbon Fiber Reinforced Polymer (CFRP) is chosen as the material as it has light weight and also high strength. Finite element modeling is performed in order to check the impeller designs for failure. It is found that the impeller is able to sustain high rotational stresses using CFRP material. The manufacturing process of the impeller consists of winding endless fibers of CRFP on a commercially available winder suitable for CAD/CAM integration. With this design, also the motor and the bearings can be integrated with the impeller. Further, the interweaving of electrical components enables shaftless designs. This in turn allows for implementing conveniently multiple counter rotating impellers in axial and mixed flow configurations. Consequently this promises to considerably reduce overall costs of production of such high-performance impellers that even have an outer shroud as inherent element of the design.
A New Modeling Framework for Piezoresponse Force Microscopy
Authors: Salehi-Khojin Amin , Jalili Nader
Published: May 2009

Piezoresponse force microscopy (PFM) has evolved into useful tool for measurement of local functionality of ferroelectric materials which shows great potential for applications such as data storage, ferroelectric lithography and nonvolatile memories. Better understanding of current techniques which are applied in the scale of single grain requires a straightforward analytical theory to map the PFM response for a wide range of typical experimental parameters. To this end, a new modeling framework is presented for a PFM which is modeled as a suspended cantilever beam with a tip mass. More specifically, the beam is considered to vibrate in all three directions, while subjected to a bias input voltage. The Hamilton’s principle is used to derive the governing equations. The local electrostatic forces on the tip and distributed forces acting on the cantilever are also taken into account in the current modeling framework. Since the sample and tip are in the contact mode and any changes in the topography of surface will affect the indentation depth of indenter, the boundary control input force is used at the base unit. Moreover, the free end of beam with the equivalent mass of tip is connected to springs in the vertical, longitudinal and lateral directions to represent the resistance of piezoelectric material to tip movement. It is shown that the vertical bending is coupled to longitudinal displacement and lateral bending is coupled to torsion through the friction between tip and sample.
A Closed-Form Distributed-Parameters Modeling Framework for Piezoresistive-Based Microcantilever Sensors With Application to Nanoscale Force Measurement
Authors: Saeidpourazar Reza , Jalili Nader
Published: May 2009

This paper presents a closed-form distributed-parameters based modeling framework for a piezoresistive microcantilever. Due to the variety of applications in biological and material science technologies, microcantilevers have recently received widespread attention. Due to their extreme sensitivity and simplicity, piezoresistive microcantilevers are widely used in variety of sensing applications; however, most of the current studies focus on a simple lumped-parameters modeling rather than modeling of the piezoresistive microcantilevers itself. Due to the applications of the piezoresistive microcantilevers in nanoscale force sensing or non-contact Atomic Force Microscopy (AFM), which are involved with the forces in the range of nano-Newton to pico-Newton, precise modeling of the piezoresistive microcantilevers is essential. Instead of the previously used lumped-parameters modeling, a distributed-parameters modeling is proposed and developed here to achieve the most precise model of the piezoresistive microcantilever with tip-mass, tip-force and base movement. In order to utilize online control and real-time sensor feedback, there is a need to have a closed-form relationship between microcantilever’s piezoresistive output voltage as a function of tip force and the base motion. To achieve this, utilizing a novel approach a closed-form modeling framework for the piezoresistive microcantilever is presented. Following the mathematical modeling, simulation results are presented to show the accuracy of the proposed distributed-parameters modeling when compared with the previously reported lumped-parameters modeling approach.
Experimental Study on Utilizing Delayed-Feedback for Ultra-Sensitive Sensing
Authors: Bradley Calvin , Daqaq Mohammed F. , Jalili Nader
Published: May 2009

Cantilever-based mass sensors have recently emerged as an effective device for label-free detection of ultra small masses. To improve their sensitivity, a new concept based on delayed-position feedback is proposed and implemented. The proposed approach utilizes feedback delays and inherent system nonlinearities to produce stable limit-cycle oscillations. These limit cycles are generated as a result of the trivial solutions loosing stability via a supercritical Hopf bifurcation. The amplitude of the limit cycles is shown to be ultra sensitive to variations in the sensor natural frequency. This creates an ultra-sensitive cantilever-based mass sensing platform which does not require any changes or additions to the current sensor geometry and can be implemented in real time.
Design and Development of H∞ and μ-Synthesis Controllers for Nanorobotic Manipulation and Grasping Applications
Authors: Saeidpourazar Reza , Ayalew Beshah , Jalili Nader
Published: May 2009

This paper presents the development of H∞ and μ-synthesis robust controllers for nanorobotic manipulation and grasping applications. Here a 3 DOF (Degrees Of Freedom) nanomanipulator with RRP (Revolute Revolute Prismatic) actuator arrangement is considered for nanomanipulation purposes. Due to the sophisticated complexity, and expected high level of accuracy and precision (of the order of 10−7 rad in revolute actuators and 0.25 nm in the prismatic actuator) of the nanomanipulator, there is a need to design a suitable controller to guarantee an accurate manipulation process. However, structure of the nanomanipulator employed here, namely MM3A, is such that the dynamic equations of motion of the nanomanipulator are highly nonlinear and complicated. Linearizing these dynamic equations of the nanomanipulator simplifies the controller design process significantly. However, linearization could suppress some critical information about the system dynamics. In order to achieve the precise motion of the nanomanipulator utilizing the simple linearized model, H∞ and μ-synthesis robust controller design approaches are proposed. Following the development of the controllers, numerical simulations of the proposed controllers on the nanomanipulator are used to verify the positioning performance.
Numerical Modeling of Turbulent Flow and Heat Transfer Within a Bayonet Tube
Authors: Sun Feng , Wang G.-X.
Published: May 2009

This paper presents a numerical study of turbulent flow and heat transfer in a bayonet tube under steady state. First, various turbulent models and wall treatment methods have been tested and validated against the experimental result from a turbulent air jet. The proper combination of turbulent model and wall treatment is then recommended for the turbulent flow within a bayonet tube. The study focuses on the heat transfer performance at the interface of working fluid and the outer tube wall under different Reynolds numbers. Various geometry parameters are considered in this work and the impact of geometry on the heat transfer performance is investigated. Results indicate that the heat transfer at the bottom of the bayonet tube is enhanced compared with that at the straight part. At low Re (< 8000), the maximum Nu occurs at the stagnation point, while the position of the maximum Nu moves away from the stagnant point as Re exceeds 8000. The results are believed to be helpful for the optimized design of a bayonet tube with fully turbulent flows.
ABET Alignment of Learning Resources in the Engineering Pathway Digital Library
Authors: Wu Jia-Long , Agogino Alice
Published: May 2009

The Engineering Pathway (EP) digital library (www.engineeringpathway.com) strives to provide quality educational resources for learners of all age levels. ABET Engineering Criteria has been the driving force behind modern engineering education reform since its introduction at the turn of the century. In order to help engineering educators and administrators meet the challenges of developing and teaching a learning outcomes-focused curriculum, EP is linking existing resources to appropriate ABET criteria. This paper summarizes the research behind using our ABET alignment process where computational linguistics and information retrieval tools are used to augment the ABET alignment process. Experts then review these recommendations and make corrections where needed. By taking this approach, we not only shorten the time to align existing learning resources; but also improve the scalability by aligning new resources as they are being submitted. The technologies can also be applied to the development of thesauri and recommender systems that can be tailored to individual faculty needs.
Effects of Slugger Drill Bits in Drilling of Composites
Authors: Sahraie Jahromi Ashkan , Bahr Behnam , Bassi Rupindersingh , Kolhar Arvind S.
Published: May 2009

One of the problems in machining of composites is related with the fibers as reinforcement, due to their abrasiveness, causing fast tool wear and deterioration of machined surface. Among all the damages that can occur in the drilling of a composite plate, delamination is the most serious, as it can cause loss of mechanical strength of laminate plates. The main mechanism responsible for delamination is the axial thrust force exerted by the stationary center of the drill – chisel-edge – whose action is more similar to an extrusion that to a drilling. It can be shown that 40% to 50% of the thrust force is because of the chisel edge. Therefore, in this paper a new set of hollow drill bits is introduced and tested on the composite materials with different properties and drilled hole quality mainly, surface roughness, roundness, hole oversize and delamination investigated. With these hollow drill bits we were able to achieve lower thrust forces. Also drill bit geometry changed to be optimized for the best hole quality.
Time-Frequency Analysis and Built-In Reliability Test for Health Monitoring of Electronics Under Shock Loads
Authors: Lall Pradeep , Choudhary Prakriti , Gupte Sameep , Gupta Prashant , Suhling Jeff , Hofmeister James
Published: May 2009

The built-in stress test (BIST) is extensively used for diagnostics or identification of failure. The current version of BIST approach is focused on reactive failure detection and provides limited insight into reliability and residual life. A new approach has been developed to monitor product-level damage during shock and vibration. The approach focuses on the pre-failure space and methodologies for quantification of failure in electronic equipment subjected to shock and vibration loads using the dynamic response of the electronic equipment. Presented methodologies are applicable at the system-level for identification of impending failures to trigger repair or replacement significantly prior to failure. Leading indicators of shock-damage have been developed to correlate with the damage initiation and progression in shock and drop of electronic assemblies. Three methodologies have been investigated for feature extraction and health monitoring including development of a new solder-interconnect built-in reliability test, FFT based statistical-pattern recognition, and time-frequency moments based statistical pattern recognition. The solder-joint built-in-reliability-test has been developed for detecting high-resistance and intermittent faults in operational, fully programmed field programmable gate arrays. Frequency band energy is computed using FFT and utilized as the classification feature to check for damage and failure in the assembly. In addition, the Time Frequency Analysis has been used to study of the energy densities of the signal in both time and frequency domain, and provide information about the time-evolution of frequency content of transient-strain signal. Closed-form models have been developed for the eigen-frequencies and mode-shapes of electronic assemblies with various boundary conditions and component placement configurations. Model predictions have been validated with experimental data from modal analysis. Pristine configurations have been perturbed to quantify the degradation in confidence values with progression of damage. Sensitivity of leading indicators of shock-damage to subtle changes in boundary conditions, effective flexural rigidity, and transient strain response have been quantified. Explicit finite element models have been developed and various kinds of failure modes have been simulated such as solder ball cracking, package falloff and solder ball failure. This allows the physical quantification of solder ball crack damage in the form of confidence values and provides a damage index that can be utilized for the health monitoring of solder interconnects in an electronic assembly.
Vapor-Venting, Micromachined Heat Exchanger for Electronics Cooling
Authors: David Milnes P. , Khurana Tarun , Hidrovo Carlos , Pruitt Beth L. , Goodson Kenneth E.
Published: May 2009

The increasing complexity of modern integrated circuits and need for high-heat flux removal with low junction temperatures motivates research in a wide variety of cooling and refrigeration technologies. Two-phase liquid cooling is especially attractive due to high efficiency and low thermal resistances. While two-phase microfluidic cooling offers important benefits in required flow rate and pump size, there are substantial challenges related to flow stability and effective superheating. This work investigates the use of hydrophobic membrane to locally vent the vapor phase in microfluidic heat exchangers. Previous work has demonstrated selective venting of gas in microstructures and we extend this concept to two-phase heat exchangers. This paper details the design, fabrication and preliminary testing of the novel heat exchanger. Proof-of-concept of the device, carried out using an isothermal air-water mixture, found the air-mass venting efficiency exceeding 95%. Two-phase, thermal operation of the heat exchanger found the pressure-drop to be smaller compared to a two-phase, non-venting model. The paper also includes a discussion of design challenges such as membrane leakage and optical inaccessibility. The favorable results demonstrated in this first-generation, vapor-venting, micromachined, heat exchanger motivates further study of this and other novel microstructures aimed at mitigating the negative effects of phase-change. With continued research and optimization, we believe two-phase cooling is a viable solution for high heat flux generating electronics.
A Novel Highly Tunable Butterfly-Type MEMS Capacitor
Authors: Shavezipur Mohammad , Khajepour Amir , Hashemi Seyed Mohammad
Published: May 2009

MEMS parallel-plate tunable capacitors are widely used in different devices such as tunable filters and resonators because of their simple structures, high Q-factors and small sizes. However, these capacitors have low tuning range with nonlinear and highly sensitive capacitance-voltage (C-V) responses. In this paper the development of novel tunable capacitor designs exhibiting highly linear C-V responses, is presented. The designs use segmentation technique to produce lumped flexibility in capacitor’s structure. A numerical model is developed to simulate the behavior of the capacitor. When a actuation voltage is applied, the structural rigidity of the plate produces resistive force which balances the electrostatic force, causes nodal displacements and changes the capacitance. It is shown that by optimizing the shape of segments (from rectangular to trapezoidal) and adding flexible steps located under the segments, a low sensitive linear C-V response could be achieved, while maintaining high tunability. The results of numerical simulation for the capacitors designed for PolyMUMPs process demonstrate that by optimization of the segments shape and structural stiffness a combination of high tunability over 100% and highly linear C-V response is achievable.
High Speed Rotary Pulse Width Modulated On/Off Valve
Authors: Tu Haink C. , Rannow Michael B. , Van de Ven James D. , Wang Meng , Li Perry Y. , Chase Thomas R.
Published: May 2009

A key enabling technology to effective on/off valve based control of hydraulic systems is the high speed on/off valve. High speed valves improve system efficiency for a given PWM frequency, offer faster control bandwidth, and produce smaller output pressure ripples. Current valves rely on the linear translation of a spool or poppet to meter flow. The valve spool must reverse direction twice per PWM cycle. This constant acceleration and deceleration of the spool requires a power input proportional to the PWM frequency cubed. As a result, current linear valves are severely limited in their switching frequencies. In this paper, we present a novel fluid driven PWM on/off valve design that is based on a unidirectional rotary spool. The spool is rotated by capturing momentum from the fluid flow through the valve. The on/off functionality of our design is achieved via helical barriers that protrude from the surface of a cylindrical spool. As the spool rotates, the helical barriers selectively channel the flow to the application (on) or to tank (off). The duty ratio is controlled by altering the axial position of the spool. Since the spool no longer accelerates or decelerates during operation, the power input to drive the valve must only compensate for viscous friction, which is proportional to the PWM frequency squared. We predict that our current design, sized for a nominal flow rate of 40l/m, can achieve a PWM frequency of 84Hz. This paper presents our valve concept, design equations, and an analysis of predicted performance. A simulation of our design is also presented.
Active Shielding for a Novel Sensor
Authors: Zhu Haihong , Book Wayne J.
Published: May 2009

Active shield reduces the effects of both external noise/interference and parasitic capacitances of a coaxial cable. Therefore it is commonly used during the measurement of remote grounded capacitive sensors. Capacitively Coupled Resistive Sensing (CCRS) is a novel displacement measurement technology. The transduction principle of CCRS is the resistance change related to the position of the mobile member. The CCRS sensor utilizes the small capacitance between the signal pickup head and the resistive member to sense the voltage of a certain point on the resistive member. The signal is sent to the signal conditioner through a coaxial cable. Due to the parasite capacitance of the coaxial cable, the signal will be attenuated significantly. This paper introduces a method to reduce the attenuation using active shield scheme.
Pool Boiling Studies on Nano-Structured Surfaces
Authors: Sriraman S. R. , Banerjee D.
Published: May 2009

The effect of nano-structures on pool boiling heat transfer is explored in this study. The silicon nano-structures are fabricated on 4″ double-side polished silicon wafers using Step and Flash Imprint Lithography (SFIL) process. An array of “nano-fins” consisting of 200 nm diameter pillars of 100 nm height, lateral pitch of 1 μm and transverse pitch of 0.9 μm are created in a rectangular pattern on the wafer surface. The test surface is used for pool boiling experiments using PF-5060 as the test fluid (Manufacturer - 3M Co., boiling point - 56 °C). Experiments are performed under saturation and liquid sub-cooling conditions. The heat flux measurements on the nanostructures are compared with that of bare surfaces. The test rig is of constant heat flux type. Results are reported at the maximum heat flux point. The nano-structured test surface showed a 41% increase in heat flux compared to the bare test surface under the saturation test condition. The 10-degree sub-cooling and 20-degree sub-cooling test conditions showed a 19% and 27% enhancement at the maximum heat flux point respectively.
On/Off Valve Based Position Control of a Hydraulic Cylinder
Authors: Rannow Michael B. , Li Perry Y.
Published: May 2009

A method of precisely controlling the position of a hydraulic actuator using an on/off valve is developed. Since valves exhibit little power loss when they are fully open or fully closed, the proposed system is more efficient than throttling valve control and can achieve flow variation without the expense or bulk of a variable displacement pump. Mating a pulse-width-modulated (PWMed) on/off valve with a fixed displacement pump and a smoothing accumulator creates a software enabled variable displacement pump. A drawback of using digital valve control for hydraulic systems is that the relatively low speed of the currently available switching valves results in a significant ripple in the pressure and flow rate. We propose a solution to this problem by using a throttling valve to shield the actuator from the ripple in the output. This creates an effective load sensing system with the throttling valve used only to provide a small known pressure drop between the supply and the load. This approach is significantly more efficient than the conventional technique of using throttling to vary the full flow. This paper presents an averaged model of the system, a nonlinear controller to achieve position control of an actuator and a simulation based study of the effectiveness of the controller.
Modeling of the Screw-Nut Interface Dynamics of Ballscrew Drives
Authors: Okwudire Chinedum E. , Altintas Yusuf
Published: May 2009

One aspect of ballscrew drives that requires a great deal of attention when modeling is the interface between the ballscrew and nut. This is because it plays an important role in the transmission of motion, vibrations and forces from the ballscrew to the table. Current models of the screw-nut interface consider only the axial and/or torsional deflections of the ballscrew while assuming that the lateral deformations of the ballscrew are decoupled from its torsional and axial deformations so cannot be transmitted through the screw-nut interface to the table. This paper however develops a model for the screw-nut interface that considers the lateral deformations of the ballscrew in addition to its axial and torsional deformations. The result of the modeling shows that, contrary to the aforementioned assumptions, the torsional, axial and lateral deformations of the ballscrew are coupled through the screw-nut interface. Therefore a torque applied to the ballscrew via the motor actually gives rise to lateral deformations on the ballscrew which could both affect its fatigue life and potentially the positioning accuracy of the ballscrew drive. These findings are verified by experiments on a single-axis ballscrew drive.
On the Use of a Woven Mat to Control the Crack Path in Composite Sandwich Specimens With Foam Core
Authors: Lundsgaard-Larsen Christian , Berggreen Christian , Carlsson Leif A.
Published: May 2009

In the last couple of decades the use of sandwich structures has increased tremendously in applications where low weight is of importance e.g. ship structures, where sandwich panels are often built from fiber reinforced faces and foam cores. An important damage type in sandwich structures is separation of face and core (debonding). Debonds can arise as a result of defects from production when an area between face and core has not been primed sufficiently resulting in a lack of adhesion. In use, impact loading, e.g. due to collision with objects, can result in formation of a debond crack, followed by growth due to continued loading. With debonds present the structure might fail under loads significantly lower than those for an intact sandwich structure [1, 2]. A debond crack in a foam cored sandwich can propagate self similarly or kink away from the interface into either the face or core. Whether or not kinking occurs is governed by the stress state at the crack tip, e.g. described by the mode-mixity of the complex stress intensity factor and the properties of the face, core and adhesive [3]. The criticality of an existing crack can be highly dependent on the crack propagation path, since the fracture toughness of the face, core and interface are often very different. As the crack propagates in the interface or laminate the fibers in the face laminate can form a bridging zone behind the crack tip. This can increase the fracture toughness significantly since the bridging fibers provide closing tractions between the separated crack surfaces [4, 5]. The outline of a crack propagating under large scale bridging in a sandwich structure can be seen in Figure 1.