bluuebunny/crossref_metadata_2025 huggingface dataset:
On the Development of a Machining Support System to Improve Surface Finish
Authors: Osada Tsuginobu , Yano Ken’ichi , Kato Norihiko , Fofana Mustapha S.
Published: August 2012

Finishing processes such as deburring are performed on a wide variety of products in various quantities by workers on a piece-by-piece basis. Accordingly, the accuracy of the product depends on the worker’s skill. The aim of this research is to develop a finish machining support system. The machining is supported by using a haptic device and controlled by a bilateral control system. Here, we propose a original bilateral controller which have the gain components on the line used to transfer the force signal between master and slave robot. These gains change the binding force between master and slave robot to change the construct of the system. The effectiveness of this system is shown in simulations using haptic device and virtual model of slave robot.
Wave Propagation in Two Dimensional Periodic Composites
Authors: Sadeghi Hossein , Srivastava Ankit , Griswold Ryan , Nemat-Nasser Sia
Published: August 2012

In this paper we present theoretical calculations and experimental results concerning acoustic wave propagation in a 2-D periodic composite. It is known that the microstructure below the length scale of the wavelength affects the macroscale wave and makes the composite dispersive [1,2]. This dispersion manifests as frequency dependent phase and group velocities. We present a mixed variational formulation originally proposed by Nemat-Nasser for the evaluation of the dispersive characteristics of periodic composites. We employ the formulation to calculate the dispersion relation for a two-dimensional composite consisting of brass rods embedded in epoxy. The method allows for the calculation of the band structure of the composite and the identification of the relevant modes through mode shape information. We finally present experimental results on a fabricated sample for the 2-D composite. The experiments include longitudinal and shear wave propagation through the sample. The transmitted energy of the longitudinal and shear waves are used to evaluate the location of the pass-bands and stop-bands and to compare the results with the numerical predictions.
Assembly Guidelines for High Performance Meso-Flexure Linkage Mechanisms
Authors: Gandhi Prasanna , Soni Vaibhav , Sonawale Kaustubh , Patanwala Naved
Published: August 2012

Flexure mechanism systems with ultra-high precision motion are increasingly being used for several applications including micro-measurement, micro/nano manipulation, microfabrication, data reading, writing on CD, and so on. Flexure linkages offer inherent advantages of being frictionless, highly repeatable, and having great design flexibility. Monolithic fabrication of these mechanisms limits use of multiple materials in the system and becomes expensive especially for three dimensional mechanisms. Alternative method of assembling various components of flexure mechanism is considered in this paper. Assembly guidelines for building flexure mechanisms from separately machined components are arrived at. It is found that if each of the fixed ends of the flexure mechanism is located perfectly using two pins, internal stresses are generated in the linkages and their warping does not allow the desired operation. The proposed guidelines which are based on criterion similar to Grubler’s include a very simple formulation to determine number of location pins to be used in assembly. Further guidelines are laid down to determine locations of these pins. Two flexure mechanisms, one planar and other 3D based on double parallelogram flexure linkage mechanisms are fabricated and assembled using these guidelines and found to be working with repeated assembly and disassembly.
Flow Downstream of Partially Blocked Stented Cardiac Arteries
Authors: Gogineni Aneesha , Ravigururajan T. S.
Published: August 2012

Intravascular stents play a major role in restoring the patency in atherosclerotic coronary arteries. However restenosis occurs in an artery after certain period of time. In order to obtain the consequences of various problems associated with the implantation of stent in a multiple blocked artery, an analysis is done at the blockage of artery downstream the stented region. The present paper analyzes blood flow downstream of partially blocked stented artery at different levels of blockages. The blockage rate is taken as thirty, fifty and sixty percentage of the stented artery. Velocity, flow rate and pressure drop at the blocked artery are simulated using the CFD software. The analysis illustrates an increment in velocity and pressure drop at the blockage with increase in velocity, pressure and mass flow rate at the inlet. The maximum velocity of blood in stented arteries at high percentage of blockage is more when compared to the lower ones. Due to the increase in pressure at inlet, the mass flow rate increased at the blockage downstream stented artery. The values for pressure obtained at blockage are decreasing which are in contrast to the velocity and pressure drop values at the blockage. The pressure drop at the blockage analyzes the blood pressure level in the artery which can be used for future optimizations and modifications during and after the stent implantation.
Detection of Coherence in Collocated Experimental Acceleration Signals in a Flexible Aluminum Multi-Beam Structure
Authors: Georgiou Ioannis T.
Published: August 2012

The present work concerns the study of the experimental Proper Orthogonal Decomposition (POD) modes of three simultaneously acquired ensembles of collocated impulse-induced acceleration signals in a complex multi-beam aluminum structure. The impact-induced locally transverse acceleration of a three-beam structure is measured simultaneously at three fixed points with state-of-the-art piezoelectric sensors. Each ensemble of collocated databases is processed by the POD Transform to find out that it is underlined by strong coherence in space and time manifested by a small number of POD modes. It is found that the unit space modulations of the first-the dominant-POD modes of the three databases of experimental acceleration signals form an orthonormal set. The same is true for their companion unit time modulations. This original result leads to the identification of three normal modes of vibration for the complex beam structure.
Computational Analysis of Strain Effects on Electrical Transport Properties of Crystalline Nanocomposite Thin Films
Authors: Li Hua , Li Gang
Published: August 2012

In this work, we model the strain effects on the electrical transport properties of Si/Ge nanocomposite thin films. We utilize a two-band k·p theory to calculate the variation of the electronic band structure as a function of externally applied strains. By using the modified electronic band structure, electrical conductivity of the Si/Ge nanocomposites is calculated through a self-consistent electron transport analysis, where a nonequilibrium Green’s function (NEGF) is coupled with the Poisson equation. The results show that both the tensile uniaxial and biaxial strains increase the electrical conductivity of Si/Ge nanocomposite. The effects are more evident in the biaxial strain cases.
Flywheel Energy Storage Systems for Wind Turbine Grid Frequency Stability: A Review
Authors: Durukan Ilker , Ekwaro-Osire Stephen , Bayne Stephen B.
Published: August 2012

Most recent grid codes require wind turbines to contribute to the recovery of frequency drops in the grid. More of the recently build wind turbines use variable speed generators. Unlike fixed speed generators, these generators do not naturally contribute to the recovery of the frequency drop since the rotor rpm is decoupled from the grid frequency. This decoupling is achieved by controller and power conditioning units. The studies reviewed in this paper focused on the design of such a controller so that the wind turbine could react to frequency drops. Another approach to responding to frequency drops is to connect an energy storage system to the DC bus of variable speed generator. Flywheels have been used as energy storage systems to fill energy gaps in several applications and can be used for frequency recovery application for wind turbines as well. The objective of this study was to demonstrate the improvement of frequency stability of wind turbines connected to electrical grids in the presence of flywheel energy storage systems (FESS). Studies reviewed show that FESS can enhance the power quality and frequency stability of wind turbines connected to an electrical grid.
A Study of the Impact of Team Functions in a First Year Design Course on Student Performance in Later Design Courses
Authors: Hamade Ramsey F. , Ghaddar Nesreen
Published: August 2012

In this paper, the authors report on a longitudinal study of the impact of the function that a student assumes in this introductory course on his/her performance in design courses taken later in their engineering studies. The study tracks the performance of 204 students through the curriculum up to and including the final year’s capstone design project. Tracking is accomplished using repeated measures ANOVA (RMANOVA). Potential correlations are statistically examined between the introductory course grades and subgrades of the major deliverables (report and contest) and those from the later design courses after being segregated according to team function. The findings reveal strong impact of team functions on performance in design courses taken by the students up to three years later in the curriculum. Furthermore, it was also found that 64% of all teams formed for the capstone project contained two or more of the team original members formed in ME Tools.
Integrating Coherent Porous Silicon as a Wicking Structure in the MEMS Based Fabrication of a Vertically Wicking Micro-Columnated Loop Heat Pipe
Authors: Dhillon Navdeep S. , Hogue Chris , Chan Matthew W. , Cheng Jim C. , Pisano Albert P.
Published: August 2012

System design, component-wise fabrication and experimental thin-film evaporation results are presented for a vertically wicking micro-columnated loop heat pipe. Designed for fabrication using a three-layer wafer stack, this MEMS phase change device has components etched on both sides of the middle silicon wafer that are sealed by thinner top and bottom capping wafers. A coherent porous silicon (CPS) based dual-scale micro-columnated wick design uses a primary wick for capillary pumping and a secondary surface-micro-textured wick for thin-film liquid evaporation. For etching CPS, a Teflon based wafer-level electrochemical etching setup is implemented and results from a preliminary die-level etching study are reported. The main device components, which include the fluid transport channels, the condenser section and the columnated vapor chamber in a non-CPS base, are fabricated on silicon wafers using standard MEMS fabrication techniques. Thermal experiments are performed to study the phenomena of thin-film evaporation in a columnated open-loop micro evaporator.
Nonlinear Vibration Analysis of a Micro Beam Exposed to an External Flow
Authors: Mazaheri Hashem , Hosseinzadeh Ali , Ahmadian Mohammad T. , Barari Ahmad
Published: August 2012

In this paper, nonlinear vibration of a micro cantilever exposed to a constant velocity flow is studied. In order to obtain vibration frequency and time response of the micro beam the variational iteration method is used as a novel tool for solving nonlinear differential equations. Results of the analytical solution are compared with those obtained by Runge-Kutta method which shows very good agreement between them. Results confirm that frequency of vibration depends on the flow velocity. Also, the high sensitivity of the vibration frequency to the flow velocity means that it can be an effective indicator of velocity.
Methods for Evaluating Occupant Kinematics and Seatbelt Use During a Collision
Authors: Hinger John E.
Published: August 2012

Vehicular accident investigators are frequently called upon to determine seatbelt system usage and injury mechanisms for vehicle occupants. An evaluation method using an exemplar vehicle and a surrogate occupant can be used in helping to make this determination. An understanding of the collision characteristics, injuries sustained and forensic evidence located within the vehicle can be used with a surrogate occupant in an exemplar vehicle to determine seatbelt system usage, injury mechanisms and occupant kinematics.
Employing Surface Roughness for Bridge-Vehicle Interaction Based Damage Detection
Authors: Jaksic Vesna , Pakrashi Vikram , O’Connor Alan
Published: August 2012

Damage detection and Structural Health Monitoring (SHM) for bridges employing bridge-vehicle interaction has created considerable interest in recent times. In this regard, a significant amount of work is present on the bridge-vehicle interaction models and on damage models. Surface roughness on bridges is typically used for detailing models and analyses are present relating surface roughness to the dynamic amplification of response of the bridge, the vehicle or to the ride quality. This paper presents the potential of using surface roughness for damage detection of bridge structures through bridge-vehicle interaction. The concept is introduced by considering a single point observation of the interaction of an Euler-Bernoulli beam with a breathing crack traversed by a point load. The breathing crack is treated as a nonlinear system with bilinear stiffness characteristics related to the opening and closing of crack. A uniform degradation of flexural rigidity of an Euler-Bernoulli beam traversed by a point load is also considered in this regard. The surface roughness of the beam is essentially a spatial representation of some spectral definition and is treated as a broadband white noise in this paper. The mean removed residuals of beam response are analyzed to estimate damage extent. Uniform velocity and acceleration conditions of the traversing load are investigated for the appropriateness of use. The detection and calibration of damage is investigated through cumulant based statistical parameters computed on stochastic, normalized responses of the damaged beam due to passages of the load. Possibilities of damage detection and calibration under benchmarked and non-benchmarked cases are discussed. Practicalities behind implementing this concept are also considered.
Development of Energy Absorbing Laminated Fiberglass Composites Using Electrospun Glass Nanofibers
Authors: Kimbro Evan , Kelkar Ajit D.
Published: August 2012

Failure due to delamination of composite laminates via low velocity impact damages is critical because of the subsurface nature of delamination. Traditional methods such as stitching and Z-pinning, while improving interlaminar properties in woven composites, lead to a reduction of the in-plane properties. Electrospun non-woven sheets of nanofibrous mat applied at interfacial regions offer an option to traditional treatments. The objective of the present study is to observe the energy absorption during the event of an impact upon a composite laminate. The use of Tetra Ethyl Orthosilicate (TEOS) chemically engineered glass nanofibers manufactured using electrospinning technique in woven glass fiber resin pre-impregnated composite laminates were investigated for their potential to improve the interlaminar properties. Electrospun glass nanofibers pre-impregnated woven mats were manufactured using a vacuum bag and cured in a computer controlled convection oven. The interlaminar properties of the nano engineered hybrid composites were obtained using low velocity impact tests and are compared with those without the presence of electrospun nanofiber layers, to study their influence. Impacted specimens were examined using C-scan analysis to detect impact damage dimensions. It was observed when electrospinning nanofibers were added to lamina interfaces, the electrospun fiber embedded coupons had larger impact damage area compared to the coupons without electrospun fiber layers.
Optimum Angles for Multi-Angle Elastic Light Scattering Experiments
Authors: Burr D. W. , Daun K. J. , Thomson K. A. , Smallwood G. J.
Published: August 2012

In multiangle elastic light scattering (MAELS) experiments, the morphology of aerosolized particles is inferred by shining collimated radiation through the aerosol and then measuring the scattered light intensity over a set of angles. In the case of soot-laden aerosols MAELS can be used to recover, among other things, the size distribution of soot aggregates. This involves solving an ill-posed set of equations, however. While previous work focused on regularizing the inverse problem using Bayesian priors, this paper presents a design-of-experiment methodology for identifying the set of measurement angles that minimizes its ill-posedness. The inverse problem produced by the optimal angle set requires less regularization and is less sensitive to noise, compared with two other measurement angle sets commonly used to carry out MAELS experiments.
Thermal Conductivity of Ordered Mesoporous Silicon Thin Films Made From Magnesium Reduction of Polymer Templated Silica
Authors: Fang Jin , Pilon Laurent , Kang Chris B. , Tolbert Sarah H.
Published: August 2012

This paper reports the cross-plane thermal conductivity of ordered polycrystalline mesoporous silicon thin films between 30 and 320 K. The films were produced by a combination of evaporation induced self-assembly (EISA) of mesoporous silica followed by magnesium reduction. The periodic ordering of pores in mesoporous silicon was characterized by a combination of 1D X-ray diffraction, 2D small angle X-ray scattering, and direct SEM imaging. The average crystallite size, porosity, and film thickness were about 13–18 nm, 25–35%, and 140–260 nm, respectively. The pores were arranged in a face-centered cubic lattice. Finally, the cross-plane thermal conductivity of the meso-porous silicon thin films was measured using the 3ω method. The measured thermal conductivity was about 3 to 5 orders of magnitude smaller than that of the bulk dense crystalline silicon for the temperature range considered. The effects of temperature and film thickness on the thermal conductivity were investigated.
Radiofrequency Catheter Ablation of Cardiac Arrhythmias
Authors: Ulucakli M. Erol
Published: August 2012

Radiofrequency ablation could be described as a thermal strategy to destroy a tissue by increasing its temperature and causing anirreversible cellular injury. Radiofrequency ablation is a relatively new modality which has found use in a wide range of medical applications and gained acceptance. RF ablation has been used in destroying tumors in liver, prostate, breast, lung, kidney, bones, and the eye. One of the early applications in clinical setting was its use in treating supraventricular arrhythmias by selectively destroying cardiac tissue. Radiofrequency ablation has become established as the primary modality of transcatheter therapy for the treatment of symptomatic arrhythmias. Radiofrequency catheter ablation of cardiac arrhythmias were investigated using a finite-element based solution of bioheat transfer equation. Spatial and temporal temperature profiles in the cardiac tissue were visualized.
Evolving Systems: Adaptive Key Component Control With Persistent Disturbance Rejection
Authors: Balas Mark J. , Frost Susan A.
Published: August 2012

This paper presents an introduction to Evolving Systems, which are autonomously controlled subsystems which self-assemble into a new Evolved System with a higher purpose. Evolving Systems of aerospace structures often require additional control when assembling to maintain stability during the entire evolution process. This is the concept of Adaptive Key Component Control which operates through one specific component to maintain stability during the evolution. In addition this control must overcome persistent disturbances that occur while the evolution is in progress. We present theoretical results for the successful operation of Adaptive Key Component control in the presence of such disturbances and an illustrative example.
Trans-Scleral Tonometry: Mechanical Palpation of the Eye
Authors: Polyva´s Pe´ter P. , Enikov Eniko T. , Peyman Gholam , Polyzoev Vasco
Published: August 2012

The development of new tonometers requires laboratory tests on enucleated eyes where the intraocular pressure (IOP) is usually controlled by the use of a fluid column (manometry). This article describes a novel eye pressure regulation system for IOP tests along with a new concept of mechanical palpation tonometry. Manometry is commonly regarded as an invasive technique that can measure precisely the pressure inside the eye. It is a common laboratory technique for evaluating changes in IOP over time, and for providing reference pressure by which all other tonometers can be evaluated. In general, the system consists of a fluid column (1% saline solution) connected via PVC tubing to a three way valve. The valve is able to connect the column branch to a syringe with a 21G needle inserted into the vitreous humor and to a pressure transducer. The syringe needle is inserted in the eye through the side, with the tip located approximately in the middle of the vitreous chamber [1]. However, this method is prone to errors due to the gelatinous and highly fibrous nature of the vitreous matter that could easily clog the syringe needle and prevent the accurate pressure control and measurement. To resolve this difficulty, we report an alternative control of the IOP through the anterior chamber of the eye. In addition to the clogging, severed blood vessels in enucleated eyes result in large rate of leakage of intraocular fluid. With these modifications in place, it was demonstrated that the pressure sensing is fast and accurate, allowing investigation of mechanical trans-scleral palpation and the development of a new concept of mechanical palpation tonometry device. The device is based on multiple probes for measuring contact forces. Experimental data from the performance of the device are presented.
Progressive Clearance Labyrinth Seal for Turbo-Machinery Applications
Authors: Roy Binayak , Deo Hrishikesh V. , Zheng Xiaoqing
Published: August 2012

Turbomachinery sealing is a challenging problem due to the varying clearances caused by thermal transients, vibrations, bearing lift-off etc. Leakage reduction has significant benefits in improving engine efficiency and reducing emissions. Conventional labyrinth seals have to be assembled with large clearances to avoid rubbing during large rotor transients. This results in large leakage and lower efficiency. In this paper, we propose a novel Progressive Clearance Labyrinth Seal that is capable of providing passive fluidic feedback forces that balance at a small tip-clearance. A modified packing ring is supported on flexures and employs progressively tighter teeth from the upstream to the downstream direction. When the tip-clearance reduces below the equilibrium clearance, fluidic feedback forces cause the packing ring to open. Conversely, when the tip-clearance increases above the equilibrium clearance, the fluidic feedback forces cause the packing ring to close. Due to this self-correcting behavior, the seal provides high differential pressure capability, low leakage and non-contact operation even in the presence of large rotor transients. Theoretical models for the feedback phenomenon have been developed and validated by experimental results.
Molecular Dynamic Computer Simulation Models for Teaching Thermodynamic Principles
Authors: Dartnall W. John , Reizes John A.
Published: August 2012

Modern mechanical engineers need to learn more than the traditional classical approaches to thermodynamics and heat transfer. Matter is comprised of molecules and in many situations the behavior of these molecules may be modeled using hard spheres whose motion is governed by Newtonian mechanics. This is particularly true in those situations involving relatively low density gases, that are valuable in introducing the concepts of thermodynamics. This paper presents some models that have been developed using simple-to-use software that students can handle in a time-efficient way during class-room situations, using only Newtonian Mechanics. Experience indicates that students have many conceptual difficulties when studying engineering thermodynamics. Simple molecular dynamic approaches promise to give students a more intuitive understanding of these thermal areas.
Device Packaging Techniques for Implementing a Novel Thermal Flux Method for Fluid Degassing and Charging of a Planar Microscale Loop Heat Pipe
Authors: Dhillon Navdeep S. , Cheng Jim C. , Pisano Albert P.
Published: August 2012

A novel two-port thermal flux method is implemented for degassing a microscale loop heat pipe (mLHP) and charging it with a working fluid. The mLHP is fabricated on a silicon wafer using standard MEMS micro-fabrication techniques, and capped by a Pyrex wafer, using anodic bonding. For these devices, small volumes and large capillary forces render conventional vacuum pump-based methods quite impractical. Instead, we employ thermally generated pressure gradients to purge non-condensible gases from the device, by vapor convection. Three different, high-temperature-compatible, MEMS device packaging techniques have been studied and implemented, in order to evaluate their effectiveness and reliability. The first approach uses O-rings in a mechanically sealed plastic package. The second approach uses an aluminum double compression fitting assembly for alignment, and soldering for establishing the chip-to-tube interconnects. The third approach uses a high temperature epoxy to hermetically embed the device in a machined plastic base package. Using water as the working fluid, degassing and filling experiments are conducted to verify the effectiveness of the thermal flux method.
Short-Pulse Laser-Based System for Detection of Tumors: Administration of Gold Nanoparticles Enhances Contrast
Authors: Sajjadi A. Y. , Suratkar A. , Mitra K. , Grace M. S.
Published: August 2012

The objective of this paper is to demonstrate the use of gold nanoparticles, which accumulate in tumors due to the leakiness of tumor vasculature, as contrast agents for enhanced imaging in a time-resolved optical tomography system using short-pulse lasers for skin cancer detection. Mouse tissue was analyzed in vivo by optical coherence tomography during exposure to the beam of either a 514nm, 200ps pulsed laser or a 776nm, 1.3ps pulsed laser. It was found that addition of spherical gold nanoparticles, either by injection under the skin or by intravenous administration, decreased total reflection intensity and broadened the temporal profile of reflected photons. Together, these results show that gold nanoparticles tuned to the wavelength of the laser can enhance contrast between labeled and unlabeled tissues, and suggest that gold nanoparticles may enhance the sensitivity and resolution of laser-based cancer detection and therapeutic treatment.
Bending and Impact Properties of Biaxial Weft Knitted Composites
Authors: Demircan O¨. , Torun A. R. , Kosui T. , Nakai A. , Hamada H.
Published: August 2012

In order to improve the mechanical properties of weft knitted fabric, straight yarns both in weft and warp directions can be integrated. These types of reinforcements are called biaxial weft knitted structures. Biaxial weft knitted fabrics include weft and warp yarn layers, which are held together by a stitching yarn system. Reinforcing yarns, e.g. glass or aramid fibers, can be used within all yarn systems. They provide necessary strength and stiffness of the fabric [1]. The present work concentrates on the mechanical properties of biaxial weft knitted composites. Mainly the effect of stitch yarn type such as aramid, glass and nylon and biaxial, warp and weft, yarn type such as aramid and glass were investigated. Six plies composite panels were fabricated by hand lay-up lamination method. Volume fraction (Vf) of all composites were kept constant. After production of composites, bending and impact tests had been conducted. GF-GF-NY composites exhibited superior flexural property than other tested composites. It was found that GF-GF-AR composites have higher impact properties (total energy and maximum load) than other tested composites. Better mechanical properties can be achieved by using aramid stitch yarn with combination glass warp and glass weft yarns. A better interfacial bonding of aramid stitch yarn seemed to be cause of this result. After impact test, fracture aspects of reverse side of weft knitted composites were analyzed. The crack propagation was explained by visual inspection. Moreover, impact damage for tested materials was evaluated by cross-sectional observations. For the better understanding of the fracture behavior, schematic drawings of all kind of specimens were drawn. To analyze the damage behavior of tested specimens, the damage lengths were measured. By this observation, the tendency between impact energy and crack length was showed.
Integration of Climate Change in the Analysis and Design of Engineered Systems: Barriers and Opportunities for Engineering Education
Authors: Lucena Juan , Delborne Jason , Johnson Katie , Leydens Jon , Munakata-Marr Junko , Schneider Jen
Published: August 2012

The goal of this paper is to begin mapping perspectives of engineering faculty on barriers and opportunities related to the integration of climate change in the analysis and design of engineered systems (CC&ES). Although both sustainability and renewable energy have been receiving increasing attention in engineering education for quite some time, climate change, especially as it relates to engineered systems, has yet to become a widely accepted topic of teaching and research. From recent literature on engineering education and from interviews with engineering faculty, a picture emerges of whether and how climate change is an important dimension in the analysis and design of engineered systems. From those sources, we begin to see what it might take to incorporate the relationship between climate change and engineered systems in engineering education, what the barriers and opportunities to this incorporation might be, and what strategies might be available to institutionalize this incorporation in engineering education. Support for this paper comes from a larger research project on “Climate Change, Engineered Systems, and Society” which has the goal to develop conceptual and educational frameworks and networks of change agents to promote effective formal and informal education for engineering students, policymakers and the public at large. The project partners include the National Academy of Engineering (NAE), Arizona State University, Boston Museum of Science, Colorado School of Mines (CSM), and the University of Virginia. Within this larger team, the CSM team is planning to develop a testbed for the incorporation of CC&ES in engineering education. Hence, our first step is to find related curricular innovations in the engineering education literature and perspectives from engineering faculty on barriers and opportunities to the integration of CC&ES in engineering education.
Analysis of a Reheat Carbon Dioxide Transcritical Power Cycle Using a Low Temperature Heat Source
Authors: Tuo Hanfei
Published: August 2012

The CO2 transcritical Rankine power cycle has been widely investigated recently, because of its better temperature glide matching between sensible heat source and working fluid in vapor generator, and its desirable qualities, such as moderate critical point, little environment impact and low cost. A reheat CO2 transcritical power cycle with two stage expansion is presented to improve baseline cycle performance in this paper. Energy and exergy analysis are carried out to investigate parametric effects on cycle performance. The main results show that reheat cycle performance is sensitive to the medium pressures and the optimum pressures exist for maximizing net work output and thermal efficiency, respectively. Reheat cycle is compared to baseline cycle under the same conditions. More significant improvements by reheat are obtained at lower turbine inlet temperatures and/or larger high cycle pressure. Work output improvement is much higher than thermal efficiency improvement, because extra waste heat is required to reheat CO2. Based on second law analysis, exergy efficiency of reheat cycle is also higher than that of baseline cycle, because more useful work is converted from waste heat. Reheat with two stage expansion has great potential to improve thermal efficiency and especially net work output of a CO2 transcritical power cycle using a low-grade heat source.
Effect of Axial Prestress on Thermoelastic Damping in Micromechanical Beam Resonators
Authors: Gu Wenting , Cheng Peng , Hao Julie
Published: August 2012

Axial prestress is built into those micromechanical beam resonators made of deposited thin films. This prestressaffects elastic strain distribution in a beam resonator and thus has the potential of changing its thermoelastic damping (TED). In this paper, a theoretical model of TED in a micromechanical beam resonator with axial prestressis developed to study the effect of axial prestress on TED in such resonators. This theoretical model is built upon a thermal-energy method and therefore TED is calculated as the generated thermal energy during one cycle of vibration. An explicit expression for the QTED, the Quality factor due to TED, is obtained from this developed model. As a result, this work suggests that, for a beam resonator with axial prestress, its QTEDincreases with tensile prestressand decreases with compressive prestress.
Multi-Attribute Balancing Process for Automotive Components
Authors: El-Sayed Mohamed E. M. , Stawiarski Ted , El-Sayed Jacqueline A. J.
Published: August 2012

Meeting customer demands in the form of product multiattributes during the Automotive Product Development Process is the key for achieving superior product quality. Using the Voice of the customer expressed in these multi-attributes to develop Vehicle, Subsystems, and Components Technical Specifications is a necessary step during the early phases of the process. Achieving these multi and sometimes conflicting attributes, however, is the main challenge and the real measure of the process success. In this paper, a general approach to multi-attribute balancing in Automotive Product Development Process is presented. The development of vehicle technical specification based on the voice of the customer is addressed. The processes to flow vehicle level attributes to subsystems and components design targets and constraints are outlined. A resolution process for resolving conflicts between these targets during the early design phases is presented. To demonstrate the application of the resolution process and the steps for multi-attribute balancing of automotive components three different automotive examples are discussed.
Experimental Investigation of Thermal Transport Mechanisms Through a Nanoscale Point Contact
Authors: Pettes Michael Thompson , Shi Li
Published: August 2012

Using a silicon nitride cantilever with an integral Si tip and a micro-fabricated Pt-C resistance thermometer placed close to the tip, we have measured the thermal contact resistance of a nanoscale Si point contact in an ultrahigh vacuum atomic force microscope at near room temperature. The temperature of the cantilever tip was observed to remain constant during approach to, while in contact with, and during retraction from the Si substrate, while a large temperature drop was observed at the points of contact and separation, suggesting negligible near-field radiation transport in the experiment reported here. Detailed contact mechanics calculations of the contact diameter and modeling of the nanocontact show that solid-solid conduction with phonon transmission coefficient of at least 0.12 is the dominant mode of heat transfer through the nanoscale contact.
Design of Experiment to Evaluate Thermal Resistance of a PTAC Unit
Authors: Leylegian J. C. , Naraghi M. H. , Montoni S. , Kaszczak M. , Garafolo V.
Published: August 2012

As a part of the “Design of Experiment” component of Thermal/Fluids Laboratory (MECH405) at Manhattan College, a setup for measuring the R-value of an Evergreen Products Model KHS-09 PTAC unit was designed by a student group. The setup consisted of the PTAC unit installed in a well insulated wall. A thermally controlled hot chamber (which simulated a hot outdoor environment) was built around the exterior side of the wall and PTAC assembly. The interior side was exposed to the lab air temperature (typically at 70°F). Thermocouples were installed on various surfaces of the setup and temperature history data were collected in order to calculate the R-value of the PTAC under different imposed temperature gradients and convection heat transfer environments. ANOVA analysis of the data showed that the R-value of the PTAC was influenced by the convective environment (free versus forced convection), and while outdoor temperature did not directly influence the R-value, an interaction existed between temperature and convection.
Nano-Watt Heat Flux Sensor Considering Contact Resistance at Thermopile Junctions
Authors: Nam Sung-Ki , Jeong Su-Heon , Lee Sun-Kyu
Published: August 2012

This paper presents design and fabrication procedures for nano-Watt resolution of heat flux sensor. To enhance the resolution, a contact resistance of thermopile is especially focused. CMOS (Complementary Metal-Oxide Semiconductor-compatible) process was used for deposition of gold and chromium which are composed of thermopile. The most important part of thermopile is the contact region of the junctions which generate electrical noises as well as thermoelectric power. The effect of contact conditions at junction point was investigated. The fabricated sensor has 100 thermocouples connected in series and its active junction is on the membrane which directly affects the sensitivity. Developed sensor system provides 0.0629V/nW of sensitivity and 1nW of high resolution.
Fabrication of Micropatterns on Channel Sidewalls Using Strain-Recovery Property a Shape Memory Polymer
Authors: Chakraborty Anirban , Liu Xinchuan , Luo Cheng
Published: August 2012

Current microsystems primarily have a planar form. On the other hand, substrate sidewalls of these microsystems have not been well used in constructing devices. When patterns are generated on those sidewalls, they could be potentially used as electronic components of 3-D circuits or vertical interconnects. Existing photo-lithographic approaches are not capable of patterning the sidewalls of structures. Therefore, in this work, we have developed a novel method to generate line and dot patterns on the sidewalls of microchannels using strain-recovery property of polystyrene (PS), which is a thermal shape-memory polymer. The fabrication procedure consists of three basic steps. Firstly, microchannels were generated on a PS film using oxygen reactive ion etch. Secondly, 50 nm-thick Ag lines (100-, 150-μm-wide) and dots (50 × 50 μm2) were sputtered on the etched PS film with the aid of another SU-8 stencil. Thirdly and finally, the PS film was heated to 160 °C for 30 min. This caused the decrease in width and increase in depth of the channels induced by the strain recovery of the PS. The sidewall inclination of the microchannels increased greatly after heating causing the Ag lines and dots to transfer to the channel sidewalls. These experimental results demonstrate the possibility of fabricating Ag lines and dots on the sidewalls of an array of microchannels using the developed approach.
Micro-Rotational Generator
Authors: Rivera-Nieves Amarilys , Cordero-Vazquez Rolando , Carbajal Gerardo , Romero Edwar , Neuman Michael R. , Warrington Robert O.
Published: August 2012

Energy harvesting is a relatively new research area that extracts energy from the surroundings to power autonomous systems. This project presents a generator that harnesses the motion of high speed rotational motors for machine health monitoring. Wireless accelerometer-based sensors for detecting crack initiation on rotating shafts are typically limited by the battery finite lifetime. Miniature generators attached to rotating shafts can scavenge small amounts of energy for powering such monitoring systems. Electromagnetic induction approaches (using coils and magnets) have been widely described in literature for larger machines but few at the micro-scale. This paper investigates a multiple-pole permanent magnet design with multiple-stacks of planar coils for energy generation without using Silicon-based processing at the micro-scale. Planar coils are manufactured from 18μm thick Copper-clad on 25μm thick polyimide. The 25mm diameter coils were stacked and bonded with cyanoacrylate for a stacked thickness of 360μm. The rotor was made of a 25mm in diameter (2mm thick) CNC machined PMMA disk with 20 slots (1mm×2mm×6mm) for placing commercial NdFeB permanent magnets. The entire generator had a volume smaller than 1.5cm3. Experimental results show that the generator is capable of producing an average voltage output of 15.5V and 727mW of power (with a matching load) at a constant rotational speed of 29,500rpm.
The Effect of Blade Lean, Twist and Bow on the Performance of Axial Turbine at Design Point
Authors: Karrabi Hadi , Rezasoltani Mohsen
Published: August 2012

An investigation to understand the impact of twisted, leaned and bowed blades on the performance of axial turbine was undertaken. A CFD code, which solves the Reynolds-averaged Navier–Stokes equations, was used to compute the complex flow field of axial turbine. The code was validated against existing Hannover turbine experimental data. Numerical data showed good agreement with measured data. Finally, the effect of geometry changes, focusing on blade lean, twist and bow, on the Avon turbine blade performance, was analyzed. Results show that twisted blade affects performance significantly. Leaned and bowed blade has minor effect on performance.
Transport and Deposition of Elongated Particles in the Upper Airways
Authors: Tian L. , Ahmadi G.
Published: August 2012

Transport and deposition of elongated particle and fibers have been of interest due to their pathological responses. In this work, the transport and deposition of elongated particles and ellipsoidal fibers were numerically simulated in a physiological realistic multi-level lung model. Detailed motion of the inhaled fibers and their interaction with the surrounding environment were reproduced by solving the system of coupled equations governing the elongated particles translational and rotational motions. Correlations between the deposition pattern, fiber characteristics, breathing rates, and airway morphology in human upper tracheobronchial airways were analyzed. The results were compared with experimental measurements, and good agreement was found.
The Ideal Control Curves of Low Stress Precision Cropping Experimental Study on Metal Bar
Authors: Zhao S. D. , Zhao R. F. , Zhong B. , Tang Y. , Xu F.
Published: August 2012

In this paper, the new low stress precision cropping with a rotary swaging machine is reported (investigated). The basic working principle of the new radial-forging cropping method is discussed in detail. In order to analyze how to improve the quality of the cropped billets and decrease the cropping time, the new low stress precision cropping process technique designs six kinds of control curves including stroke-time and frequency-time to analyze and verify cropping. The experiment of cropping toward the bars that its material is 20Cr is described. Through comparing the different influence on the quality of the cross-section and cropping time that various control curves have, the ideal control curves are obtained. And different kinds of bars are used for the controllable radial impacting experiment. Finally, by comparing analysis, the paper verifies that the ideal control mode is the combination of the “linear-increment” in stroke-time curve and “linear-decrement” in frequency-time curve.
Flow and Heat Transfer Characteristics of Heterogeneous Nanofluids in Pipes
Authors: Alammar Khalid N. , Mohammed Abdullah
Published: August 2012

Heterogeneous nanofluid flow in pipes is simulated. Assuming incompressible, axisymmetric, and laminar flow, effect of nanoparticle distribution and Prandtl number on flow and heat transfer characteristics is investigated. With nanoparticle overall volume concentration of 0.05, up to 20% heat transfer enhancement was predicted for fully developed heterogeneous flow compared to homogeneous nanofluid. At the entrance region, the enhancement is shown to increase with increasing Prandtl number.
Noninvasive Acceleration Measurements of Physiological Vibrations: Assessment of Finger Arthritis
Authors: Reddy Narender P. , Dharaiya Ekta Shah , Rothschild Bruce M.
Published: August 2012

Noninvasive measurements are fast gaining importance in every clinical discipline. Noninvasive acceleration measurements of physiological vibrations may aid in clinical diagnosis and quantitative assessment of various diseases. In the discipline of rehabilitation medicine, Reddy et al [1–4] have developed and clinically evaluated the techniques of non-invasive quantitative assessment of the swallowing mechanism in dysphagic patients, using noninvasive measurements of acceleration at the throat. In the discipline of rheumatology, Reddy et al.[5] have used acceleration signals to distinguish osteoarthritis, rheumatoid arthritis, and chondromalacia of the knee joint. Rangayyan et al [6] have used acceleration signals from the knee joint to classify articular cartilage pathology. Reddy et al [7] have reported measurement of acceleration for differential diagnosis of spondylo-arthropathy from rheumatoid arthritis of the knee joint.
Water Loss by Evaporation From Partially Covered Water Bodies
Authors: Nguyen C. N. , Huynh B. P.
Published: August 2012

Fresh water is a very precious commodity in most parts of the world; and much of it is held in lakes and reservoirs. Yet significant amount of this water is continuously lost due to evaporation, especially during hot seasons. One way to reduce this loss is to cover the water surface. However, due to its often large size, it is not practical to cover it totally. Furthermore, environmental considerations (like access to the water for water birds, not turning the water bodies into “hot soup”, etc.) would render such attempt at total cover very undesirable. Instead, it is proposed here to partially cover these water bodies with floating covers which are of manageable size and easy to manufacture. They are supported by floats and leave an air gap (for environmental reasons) above the water surface. In this work, the covers are of hexagonal shape; and when used they together cover about 60% of the water surface area. Measurements have been conducted in situ of day-time evaporation levels from covered and uncovered water tanks, along with weather data (wind speed and direction, air temperature, solar radiation, and humidity) during a summer season (excluding rainy days) at a Sydney suburb. Results have shown that depending on the weather, reduction of evaporation in the range of 5–30% has been achieved with the covers. Results from this work also helps with understanding the evaporation process from lakes and reservoir, and the design of better covers.