bluuebunny/crossref_metadata_2025 huggingface dataset:
Finite Element Model for Investigation of Disc Degeneration Under Dynamic Loads
Authors: Jang Taek Hyun , Ekwaro-Osire Stephen , Gill J. Brian , Hashemi Javad
Published: August 2009

Complex biological structures involve uncertain parameters that may produce unexpected responses in the structures. The cervical spine is one of the most complex structures in human body. It is essential to consider the uncertainties contained in the cervical spine for accurate injury analysis. For this research, a finite element (FE) model of cervical spine column is created based on medical images. The FE model involves the skull, the vertebral body (C1-T1), the disc between adjacent vertebral bodies, and the ligaments. The disc consists of the annulus, nucleus, and fiber. The material property and disc height are adjusted for the disc degeneration levels in FE analysis. The FE model is validated with the experimental data. Probabilistic FE analysis is used to account for uncertainties of cervical spine components. Material properties of the disc are considered as random variables, which are defined by means, standard deviations, and distributions. In this study, the probability of injury of the disc, under dynamic loading, is investigated at various disc degeneration levels under dynamic loads. The result shows that the probability of injury was drastically increased with the disc degeneration levels. Even if the disc fracture was not reported and the magnitude of stress was small in whiplash loading, the possibility of disc injuries is increased when a degenerated disc was exposed to whiplash loading. The results presented in this research make a contribution to the understanding of age-related whiplash injuries. The results also provide evidence that the reliability of biomechanical injury analysis is also increased by accounting for uncertain factors contained in biological structures.
Conceptual Design of NDT Field Inspection System
Authors: Mielke Ross , Klose Dustin , Hansen Jarod , Wire Matt , Goblish Adam , Feldhacker John , Delfanian Fereidoon
Published: August 2009

Efforts to effectively determine the life of a cannon barrel have now been extended to developing a conceptual design for a nondestructive testing system to evaluate the condition of gun barrels in the field. This paper describes the development of an autonomous vehicle capable of traveling the length of a large caliber cannon barrel to scan the interior surface for cracks and flaws that would indicate that the barrel needs to be decommissioned. This robotic vehicle carries a bore scope to provide visual inspection and an ultrasonic transducer (UT) with which to examine the barrel. The UT data collected is stored on a computer for both real-time analysis and statistical computational usages. The data and images collected from the bore scope are then used to monitor and predict fatigue related stress cracks in the barrel material. The system is designed to be portable and to be capable of being used in remote locations where these weapons are deployed. The non-destructive testing capabilities of this equipment will help to make the large caliber cannon barrels both safer and more reliable. The increased number of inspections possible with this portable field system will improve the crack detection process and thereby increase the safety of the weapons for the soldier/operators, as well as efficiently and effectively monitor the usable life associated with large caliber cannons.
Simulator Validation Results and Proposed Reporting Format From Flight Testing a Software Model of a Complex, High-Performance Airplane
Authors: McGovern Seamus M.
Published: August 2009

Computer simulations are often used in aviation studies. These simulation tools may require complex, high-fidelity aircraft models. Since many of the flight models used are third-party developed products, independent validation is desired prior to implementation. Due to the variety of processes used by the different industries and organizations that make use of flight models, the proprietary nature of some desired data, the relative availability of data-rich pilot manuals, and their standardized, rigorous nature, formal processes based in experimental and certification flight test are proposed for objectively and consistently validating these models and their associated aircraft types. The results of application of these detailed flight test techniques is then reported using a blade element theory-based flight model with a complex, high-performance aircraft model. Finally, a concise data analysis and reporting format is proposed and demonstrated using this same aircraft model.
Bubble Nucleation on Nanoscopically Smooth Hydrophobic Islands
Authors: Nam Youngsuk , Ju Y. Sungtaek
Published: August 2009

We report our study of an interfacial gas phase formed between a smooth hydrophobic surface and water using pool boiling experiments. Nanoscopically smooth hydrophobic islands of 10 ∼ 100 μm in width are fabricated on a hydrophilic silicon substrate using photolithography. We observe sustained bubble nucleation at superheat as low as 9 °C. The amount of dissolved gas in water does not have a significant effect on bubble nucleation. By comparing the measured minimum superheat for the onset of bubble nucleation with theoretical prediction, we provide indirect evidence for the presence of an interfacial gas phase with widths on the order of 1 μm and contact angle >160°. This high contact angle, which has been postulated to be the reason for the long lifetime of nanobubbles, drastically decreases the nucleation barrier, even on nanoscopically smooth hydrophobic surfaces.
Friction Stir Welding of Sc-Modified Al-Zn-Mg-Cu Alloy Extrusions
Authors: Hamilton Carter , Sommers Andrew , Senkov Oleg
Published: August 2009

Small additions of scandium to Al-Zn-Mg-Cu 7000 series alloys can significantly improve mechanical properties and augment the strength retention at low and elevated temperatures. This research program evaluates the residual properties of Sc-modified Al-Zn-Mg-Cu alloy extrusions joined through friction stir welding (FSW). Mechanical and corrosion testing were performed on the baseline material and on panels friction stir welded at 175, 225, 250, 300, 350 and 400 RPM (all other weld parameters held constant). A thermal model of friction stir welding is developed that utilizes an energy-based scaling factor to account for tool slip. The proposed slip factor is derived from an observed, empirical relationship between the ratio of the maximum welding temperature to the solidus temperature and energy per unit length of weld. The thermal model successfully predicts the maximum welding temperatures over a range of energy levels, and the mechanical and corrosion behavior is correlated to the temperature distribution predicted by the model.
Modeling and Simulations of Collapse Instabilities of Microbeams Due to Capillary Forces
Authors: Ouakad Hassen M. , Younis Mohammad I.
Published: August 2009

We present modeling and analysis for the static behavior and collapse instabilities of doubly-clamped and cantilever microbeams subjected to capillary forces. These forces can be as a result of a volume of liquid trapped underneath the microbeam during the rinsing and drying process in fabrication. The model considers the microbeam as a continuous medium, the capillary force as a nonlinear function of displacement, and accounts for the mid-plane stretching nonlinearity. The capillary force is assumed to be distributed over a specific length underneath the microbeam. The Galerkin procedure is used to derive a reduced-order model consisting of a set of nonlinear algebraic and differential equations that describe the microbeams static and dynamic behaviors. We study the collapse instability, which brings the microbeam from its unstuck configuration to touch the substrate and gets stuck in the so-called pinned configuration. We calculate the pull-in length that distinguishes the free from the pinned configurations as a function of the beam thickness and gap width for both microbeams. Comparisons are made with analytical results reported in the literature based on the Ritz method for linear and nonlinear beam models. The instability problem, which brings the microbeam from a pinned to adhered configuration is also investigated. For this case, we use a shooting technique to solve the boundary-value problem governing the deflection of the microbeams. The critical microbeam length for this second instability is also calculated.
Impact of Micro/Nanoscale Heat Transfer in Silicon Substrates on Thermal Interface Resistance Characterization
Authors: Ju Y. Sungtaek , Cha Gilhwan
Published: August 2009

We consider different sources of potential systematic errors in the thermal interface resistance measurements. Sub-continuum heat conduction and spatial non-equilibrium between electrons and phonons in a metal may lead to overestimation of the thermal interface resistance. The use of an erroneous substrate thermal conductivity can also cause significant systematic errors in steady- and quasi-steady state measurements of the thermal interface resistance. Our results highlight an urgent need for new systematic experimental studies to confirm the magnitude of intrinsic thermal interface resistance.
Development of a Carbon Nanotube-Based Nanoactuator for a Nano-Conveyer System
Authors: Sul Onejae , Yang Eui-Hyeok
Published: August 2009

Multi-wall carbon nanotube (MWNT)-based bimorph nanoactuators were synthesized and characterized. A thin metal film was deposited on the sidewall of MWNTs using a pulsed laser deposition method to form a bimorph nanostructure. The preliminary actuation was demonstrated using a fabricated bimorph MWNT. Thermal bending performance of the nanoactuator on a thermal stage will be further investigated by using a scanning electron microscope.
A Semi-Analytical Method for Developing the Equivalent Continuum Model of a Single Layer Graphene Sheet
Authors: Hemmasizadeh Ali , Mahzoon Mojtaba , Yavari Vahid , Khandan Rasoul
Published: August 2009

A semi-analytical method is presented to develop the equivalent continuum model for a single-layered graphene sheet. This method integrates molecular dynamics method as an exact numerical solution with theory of shell as an analytical method. The force-depth results obtained from molecular dynamics (MD) simulation of nano-indentation of a single graphene sheet are compared with the formulation for large deflection of circular plates loaded at the centre. As a result, the effective Young’s modulus and mechanical thickness of the sheet wall are independently obtained. The validity of this new approach is verified by comparing finite element modeling of nano-indentation of a single graphene sheet with molecular dynamics results available in the literature. Presented results demonstrate that the proposed method could provide a valuable tool for studying the mechanical behavior of single-layered graphene sheets, as well as efficiency of continuum theory in nano-structured material.
Correlative Flank Wear Analysis of Single Point Turning Inserts Using Acoustic Emission and Artificial Intelligence Techniques
Authors: Srinidhi R. , Sharma Vishal , Sukumar M. , Venkatesha C. S.
Published: August 2009

Wear mechanism of a cutting tool is highly complex in that the processes of tool wear results from interacting effect of machining configurations. Various output generated by the study and analysis of each tool is extremely useful in analyzing the tool characteristics in general and to make efforts to obtain the estimated tool life in particular. The gradual process of tool wear has adverse influence on the quality of the surface generated and on the design specifications in the work piece dimensions and geometry, and causes, at the worst case, machine breakdown. Advanced manufacturing demands proper use of the right tool and emphasizes the need to check the wear rate. A scientific method of obtaining conditions for an optimal machining process with proper tools and control of machining parameters is essential in the present day manufacturing processes. Many problems that affect optimization are related to the diminished machine performance caused by worn out tools. One of the indirect methods of tool wear analysis and monitoring is based on the acoustic emission (AE) signals. The generation of the AE signals directly in the cutting zone makes them very sensitive to changes in the cutting process and provides a means of evaluating the wear of cutting tools. Wear parameters obtained in the process are analyzed with the output generated by using Multi Layer Perceptron (MLP) based back propagation technique and Adaptive Neuro Fuzzy Interference System (ANFIS). The results obtained from these methods are correlated for the actual and predicted wear. Experiments have been conducted on EN8 and, EN24 using Uncoated Carbide, Coated carbide and Ceramic inserts (Kennametal, India make) on a high speed lathe for the most appropriate cutting conditions. The AE signal analysis (considering signal parameters such as, ring down count (RDC), rise time (RTT), event duration (ED) and energy (EG). Flank wear in tools and corresponding cutting forces for each of the trials are measured and are correlated for various combinations of tools and materials of work piece.
A Mathematical Model of Parathyroid Hormone Response to Acute Changes in Plasma Ionized Calcium Concentration in Humans
Authors: Shrestha Rajiv P. , Chait Yossi , Hollot Christopher V. , Chipkin Stuart , Schmitt Claus P.
Published: August 2009

A complex bio-mechanism, referred to as calcium homeostasis, regulates plasma ionized calcium (Ca++) concentration in the human body to within a narrow physiologic range which is crucial for maintaining normal physiology and metabolism. In this paper we present a qualitative model of the calcium homeostatic system and then focus on a particular sub-system, termed Ca-PTH axis. We consider the dynamics of the axis involving the response of the parathyroid glands to acute changes in plasma Ca++ concentration. We use a two-pool, linear time-varying model to describe the Ca-PTH axis. We show that this model, parameterized using a guided iterative parametrization scheme and induced hypocalcemic clamp test data, successfully predicts dynamics observed in clinical tests of induced hypercalcemia in normal humans.
Integration of 3D Modeling, FEA, Rapid Prototyping in Engineering Technology 2-Year Programs
Authors: Gailani Gaffar , Berri Sidi , Brahimi Malek
Published: August 2009

Graduates from the Associate in Applied Science (AAS) in Mechanical Engineering Technology (MECH) and Industrial Design (IND) Technology at New York City College of Technology are learning new skills in 3D modeling, Finite Elements Analysis (FEA) and Rapid Prototyping. Two year programs in engineering technology are often short of helping students to grasp all aspects of the technology. This is mainly due to the limited number of credits allowed in 2-year programs (about 60 credits). Most graduates from both MECH and IND find employment in the local industry. Growing demand from local employers compelled the department to incorporate new components in the upper level courses in both AAS programs. Students from both programs are required to take a 60 hour (4 hours/week) Advanced Solid Modeling course (IND2304). In order to address the local industry need the department decided to modify and update IND2304. In the new course, students learn to improve their design by using some of the solid mechanics techniques, stress analysis, the role of Finite Element Analysis (FEA), rapid prototyping, and applying tolerance. Students learn 3D modeling using AutoDesk Inventor. They are required to design a team based project at the end of the semester. Students learn team work and sharing information with each other. They enhance their communication skills by presenting their work at the end of the semester. Results of this new course are very encouraging. Students get very motivated by the diversity and creativity of the new design work. Some students who graduated from both programs were able to use their new design skills and team work in their current positions in the field.
Experimental and Theoretical Investigation of the Nonlinear Dynamics of an Electrostatically-Actuated Device
Authors: Alsaleem Fadi M. , Younis Mohammad I. , Ouakad Hassen M.
Published: August 2009

We present modeling, analysis, and experimental investigation for dynamic instabilities and bifurcations in electrostatically actuated resonators. These instabilities are induced by exciting a microstructure with a nonlinear forcing composed of a DC parallel-plate electrostatic load superimposed to an AC harmonic load. Because of the dominant effect of the electrostatic nonlinearity, several resonances and nonlinear phenomena are induced. Examples of these are the excitation of secondary-resonances, superharmonic and subharmonic, at half and twice the natural frequency of the microstructure. Also, local bifurcations, such as saddle-node and pitchfork, and global bifurcations, such as the escape phenomenon and the homoclinic tangling may occur. These lead to undesirable jumps, hysteresis, and dynamic pull-in instabilities in MEMS devices and structures. The present work represents an attempt to explore these topics in more depth. The first part of this paper is focused on analyzing and studying the nonlinear dynamics of a capacitive device both theoretically and experimentally with a focus on the case of primary-resonance excitation (near the fundamental natural frequency of the structure). The device is made up of two cantilever beams with a proof mass attached to their tips. A nonlinear spring-mass-damper model is utilized, which accounts for squeeze-film damping. Long-time integration for the equation of motion is used to compare with the obtained experimental data. Then, global dynamic analysis is conducted using a finite difference method (primary resonance) and shooting method (subharmonic resonance) combined with the Floquet theory to capture periodic orbits and analyze their stability. The domains of attraction (basins of attraction) for selected data are calculated numerically. Experimental data revealing primary and sub-harmonic resonances, dynamic pull-in, and the escape-from-a-potential-well phenomenon are shown and compared with the theoretical results.
Fatigue Performance of Multiwall Carbon Nanotube Composite PMMA and ABS
Authors: Bortz Daniel R. , Weisenberger Matthew , Marrs Brock , Andrews Rodney
Published: August 2009

Poly (methyl methacrylate) (PMMA) and acrylonitrile-butadiene-styrene (ABS) – multiwall carbon nanotube (MWNT) and chopped carbon fiber (CCF) composites were prepared by a melt mixing protocol at various concentrations. Specimens were fabricated and tested using constant amplitude-of-deflection fatigue testing. The numbers of cycles to failure were recorded and analyzed using the linear version of the 2-parameter Weibull model. In the PMMA matrix, the 1.0vol% MWNT reinforced composites outperformed the neat PMMA matrix by +396% while the 1.0vol% CCF composites increased fatigue life by +198% over the control. The increase in fatigue life may be attributed to the nanoscale dimensions of the MWNTs. This enables them to directly interact with the matrix at the sub-micron scale where damage such as crazing begins, which ultimately initiates a critical crack that leads to failure of the specimen. The ABS composite specimens did not show any increase in fatigue life. The underlying reasons for the lack of fatigue improvement remain unclear.
Future and Past Stretching and Flow Mixing Enhancement in Wavy Channels by the Lattice-Boltzmann Method
Authors: Sanhueza Luis E. , Guzman Amador M.
Published: August 2009

The stretching and flow mixing enhancement characteristics in mini and micro wavy channels have been investigated by solving the Boltzmann Transport Equation (BTE) with the Lattice-Boltzmann method (LBM). The Eulerian and Lagrangian flow characteristics are obtained for a 2D symmetric wavy channel with the geometrical aspect ratios r = 0.375 and 0.1875, by performing numerical simulations of a Newtonian incompressible flow and a Newtonian compressible flow. Extended and reduced domain are used for determining the existence of spatial periodicity the Eulerian and Lagrangian characteristics for increasing Reynolds numbers. The Eulerian flow characteristics for micro channels configuration are determined for different Knudsen numbers, pressure ratio and accommodation coefficients with the objective of obtaining reliable velocity and flow patterns. The Lagrangian characteristics are obtained by integrating the Eulerian velocity field. Thousands of massless fluid particles are used to determine fluid particle Lagrangian trajectories, future and past stretching fields, and Lagrangian Lyapunov exponents, which are used for determining the channel regions with high stretching and flow mixing enhancement. The numerical results demonstrate that mini and micro wavy channels flows develop different Lagrangian characteristics. In mini wavy channels, flow mixing enhancement develops for time dependent 2D flows; whereas, in micro wavy channels, future and past stretching fields describe existence of flow mixing enhancement for very low, stable and time independent Reynolds number flow regime.
Embedded Carbon Fiber Sensor for Monitoring the Residual Strain Development During an Exothermal Polymer Matrix Composite Manufacturing Process
Authors: Mori Kazuhiro , Hsiao Kuang-Ting
Published: August 2009

The strain development during the cure stage of a polymer matrix composite manufacturing process is mainly caused by the thermal expansion and the resin crosslinking shrinkage. In this non-isothermal cure stage, the electrical resistance of a carbon fiber depends on the temperature and the strain the carbon fiber experienced. In this paper, a methodology to decouple the temperature and strain effects is developed. An experimental study for characterizing the strain development history during the cure stage of a single fiber polymer matrix composite is presented. The strain development history recorded by the single carbon fiber sensor (CFS) is analyzed and discussed.
The Audible Human Project: Modeling Subject-Specific Sound Transmission in the Lungs and Torso
Authors: Royston Thomas J. , Dai Zoujun , Mazzucco Marco
Published: August 2009

A computational model for simulating sound propagation in the lungs and torso is being developed and evaluated. A theoretical model for sound propagation in the airways is coupled with an acoustic boundary element (BE) model for sound propagation in the lung parenchyma and a finite element (FE) model for sound propagation in the surrounding chest wall. Models are being validated theoretically and numerically and compared with experimental studies, including: lung-chest phantom models that simulate the lung pathology of pneumothorax; and normal human subject studies. This work is relevant to the development of advanced auscultatory techniques for lung, vascular and cardiac sounds within the torso and may be useful in the development of a more effective educational tool for teaching stethoscopic skills in the future.
Surrogate Arm Modal and Transient Response Computational Analysis
Authors: Leung Alan , Simmonds Kirth , Bagchi Amit , Matic Peter
Published: August 2009

Naval Research Laboratory has been developing measurement devices to study the dynamic response of the human body, commonly known as GelMan technologies in publications. This technology is currently being extended to upper extremity designs (GelMan-Upper Extremity, Figure 1a), consisting of upper arm and forearm with surrogate bones connected by a spherical joint and surrounded by generalized surrogate tissue. Computational low speed localized impact tests on the arm surrogate have been performed and compared to corresponding experiments. The outcome of this analysis can simulate the structural response of the arm, thus providing insight into preventing or mitigating injuries sustained from car accidents, sports and/ or battlefield injuries. A modal analysis and low speed impact transient analysis have also been performed on the arm surrogate constrained at the shoulder using the finite element program ABAQUS (Figure 1b). Linear elastic material properties from open literature are used for each arm component for the analysis using three dimensional, 8-noded hexahedral elements. Modes of vibration below 500 Hertz and strain-based frequency response have been obtained. A transient analysis of the arm is also being performed; von Mises stress contours, displacements and pressures inside the arm and total arm kinematics are extracted. These computational models have been validated with low speed, localized impact experiments using surrogate arm. Impacts of 10 N peak load are applied to upper arm and forearm of the surrogate model for 1 to 3 millisecond duration. Mode shapes of the arm are observed using a high speed camera and strain based frequency response curves are obtained. Experimental data (pressure and displacements) from transient test of the arm is compared to computational analysis. Agreement between the computational and experimental arm models provides a means for more advanced arm designs and loading situations.
Newtonian and Non-Newtonian Fluids: Velocity Profiles, Viscosity Data, and Laminar Flow Friction Factor Equations for Flow in a Circular Duct
Authors: Simpson Melissa M. , Janna William S.
Published: August 2009

Newtonian fluid flow in a duct has been studied extensively, and velocity profiles for both laminar and turbulent flows can be found in countless references. Non-Newtonian fluids have also been studied extensively, however, but are not given the same attention in the Mechanical Engineering curriculum. Because of a perceived need for the study of such fluids, data were collected and analyzed for various common non-Newtonian fluids in order to make the topic more compelling for study. The viscosity and apparent viscosity of non-Newtonian fluids are both defined in this paper. A comparison is made between these fluids and Newtonian fluids. Velocity profiles for Newtonian and non-Newtonian fluid flow in a circular duct are described and sketched. Included are profiles for dilatant, pseudoplastic and Bingham fluids. Only laminar flow is considered, because the differences for turbulent flow are less distinct. Also included is a procedure for determining the laminar flow friction factor which allows for calculating pressure drop. The laminar flow friction factor in classical non-Newtonian fluid studies is the Fanning friction factor. The equations developed in this study involve the Darcy-Weisbach friction factor which is preferred for Newtonian fluids. Also presented in this paper are viscosity data of Heinz Ketchup, Kroger Honey, Jif Creamy Peanut Butter, and Kraft Mayonnaise. These data were obtained with a TA viscometer. The results of this study will thus provide the student with the following for non-Newtonian fluids: • Viscosity data and how it is measured for several common non-Newtonian fluids; • A knowledge of velocity profiles for laminar flow in a circular duct for both Newtonian and non-Newtonian fluids; • A procedure for determining friction factor and calculating pressure drop for non-Newtonian flow in a duct.
An Industrial Application of Constructal Theory: A Constructal CPU Liquid Cooling Unit
Authors: Robbe Mauro , Sciubba Enrico
Published: August 2009

This paper explores the possibility of substituting a heat pipe CPU cooler with a Liquid Cooling Unit (LCU) that embeds a net of channels for the flow of the coolant, engineered according with Constructal Theory statements and having a substantially lower installation cost. A secondary aim of this study is to verify that the heat transfer characteristics are not too inferior than those of the heat pipe. Once the general LCU configuration has been decided upon (here, a compact assembly of stacked metallic discs has been chosen), an optimization of its performance is carried out using a genetic algorithm: the objective functions of the optimization are the average solid temperature of the device and the pressure drop inside tubes, both to be minimized, and the temperature of the fluid at tubes’ outlet, which should be maximized: the last objective function enforces the maximum heat rejection from the solid. Practical questions regarding the heat rejection in PC cooling systems, like the thermal resistance of the grease included between the cooling matrix and the CPU surface are not considered. Each level of tubes can be split only in two smaller branches.
Simulation of Flow and Heat Transfer in a Moving Bed Reactor With Cross Flow
Authors: de Lemos Marcelo J. S.
Published: August 2009

Heat transfer in a porous reactor under cross flow is investigated. The reactor is modeled as a porous bed in which the solid phase is moving horizontally and the flow is forced into the bed in a vertical direction. Equations are time-and-volume averaged and the solid phase is considered to have a constant imposed velocity. Additional drag terms appearing the momentum equation are a function of the relative velocity between the fluid and solid phases. Turbulence equations are also affected by the speed of the solid matrix. Results show temperature distributions for several ratios of the solid to fluid speed.
Design for Supply Chain: Evaluation of Supply Chain Metrics
Authors: Manohar Karthik , Ishii Kosuke
Published: August 2009

This paper describes the first phase of the authors’ Design for Supply Chain research that seeks to address supply chain excellence the product design process. In a global economy, companies must address supply chain issues beyond the traditional viewpoint of logistics, trucking, warehousing and include other considerations that affects design and manufacturing decisions. To include supply chain perspectives in the design of products and manufacturing processes, supply chain performance data play a critical role. This paper examines the source of data pertinent to design for supply chain using methods such as Customer Value Chain Analysis and Quality Function Deployment. A multi-industry benchmarking study also highlights the different approaches to Design for Supply Chain and emerging challenges of Social and Environmentally Responsible Supply Chains. The study revealed that lead time, quality and social/environmental metrics are the most important metrics for design for supply chain. Future research will address the refinement of metrics, the definition of the relevant data for product design, and effective approaches to incorporate the information into the product definition process.
A Lattice Boltzmann Method Based Numerical Scheme for Microchannel Flows
Authors: Fu S. C. , Leung W. W. F. , So R. M. C.
Published: August 2009

Lattice Boltzmann method (LBM) has been recently developed into an alternative and promising numerical scheme for modeling fluid physics and fluid flows. The equation is hyperbolic and can be solved locally, explicitly, and efficiently on parallel computers. LBM has been applied to different types of complex flows with varying degree of success, but rarely to micro-scale flow. Due to its small scale, micro-channel flow exhibits many interesting phenomena that are not observed in its macro-scale counterpart. It is known that the Navier-Stokes equations can still be used to treat micro-channel flows if a slip wall boundary condition is assumed. The setting of boundary conditions in LBM has been a difficult task, and reliable boundary setting methods are limited. This paper reports on the development of an algorithm to solve the Boltzmann equation with a splitting method that allows the application of a slip wall boundary condition. Moreover, the fluid viscosity is accounted for as an additional term in the equilibrium particle distribution function, which offers the ability to simulate both Newtonian and non-Newtonian fluids. An LBM based numerical scheme, which is suitable for micro-channel flows, is proposed. A two-dimensional nine-velocity lattice model is developed for the numerical simulation. Validation of the numerical scheme is carried out against micro-channel, micro-tube and driven cavity flows, and excellent agreement is obtained between numerical calculations and analytical solutions of these flows.
Binary Interaction of Liquid Capsules in a Shear Flow
Authors: Kalluri R. Murthy , Doddi Sai K. , Bagchi Prosenjit
Published: August 2009

Three-dimensional numerical simulations using front-tracking method are presented on the hydrodynamic interaction between two deformable particles suspended in simple shear flow. Particles are modeled as liquid capsules, that is, liquid drops surrounded by elastic membranes. Small and finite inertia are considered. Two sets of simulations are presented. In the first set, interaction between two identical capsules are considered. In the limit of zero inertia, it has been known from past research that the hydrodynamic interaction between two deformable particles results in an irreversible shift in the trajectories of the particles as one particle rolls over the other. We show that the presence of inertia can significantly alter the capsule trajectories, and the capsules engage in a symmetric spiraling motions. In the second set of simulations, we consider the interaction between two non-identical capsules which differ from each other in terms of capillary number. The interaction between them results in greater lateral separation as compared to that of an identical pair. This result suggests that the shear-induced diffusion mechanism may play an even greater role in mixing in suspension of bidisperse particles. The long-time trajectory of the non-identical capsules at finite Re shows that they move in spirals with different radii while translating along the streamwise direction. The more deformable capsule moves with smaller radius, and vice versa.
SPH Simulations of Airflow Through a Narrow Constriction
Authors: Klapp Jaime , Di G. Sigalotti Leonardo , de la Cruz Sanchez Eduardo
Published: August 2009

We simulate the flow of air through a channel with a narrow bridge passage (or throat) at high Reynolds numbers, using the method of Smoothed Particle Hydrodynamics (SPH). The depth of the channel is assumed to be infinite so that the flow is planar. A fully-developed laminar flow with a time increasing velocity is used at the inlet of the channel. The calculation is followed past the point where the airflow velocity becomes sonic (or choked) at the outlet of the throat. We have presented a theoretical model that predicts the well known experimental result that when the flow becomes critical, the pressure drop across the channel reaches a limiting value of ∼ 0.52–0.53. Our numerical calculation reproduced this result with very high accuracy.
An Intelligent Socially Assistive Robot for Health Care
Authors: Terao Junichi , Trejos Lina , Zhang Zhe , Nejat Goldie
Published: August 2009

The development of socially assistive robots for health care applications can provide measurable improvements in patient safety, quality of care, and operational efficiencies by playing an increasingly important role in patient care in the fast pace of crowded clinics, hospitals and nursing/veterans homes. However, there are a number of research issues that need to be addressed in order to design such robots. In this paper, we address two main limitations to the development of intelligent socially assistive robots: (i) identification of human body language via a non-contact sensory system and categorization of these gestures for determining the accessibility level of a person during human-robot interaction, and (ii) decision making control architecture design for determining the learning-based task-driven behavior of the robot during assistive interaction. Preliminary experiments presented show the potential of the integration of the aforementioned techniques into the overall design of such robots intended for assistive scenarios.
Tensile Deformation Study on Biological Cells
Authors: Samuel B. A. , Haque M. A.
Published: August 2009

We demonstrate experimental mechanical testing of single live biological cells in-situ under an optical microscope. Tensile loading was the mode of load application and the response of live biological cells were observed in-situ. The experimental set-up is small enough to fit within the stage of a fluorescence microscope. Bovine Aortic Endothelial cells were tested in this study and were found to be able to undergo very large applied strains without loss of cell’s mechanical integrity.
Continuous Microfluidic Biosensing With Conjugated Paramagnetic Beads
Authors: Sasso Lawrence A. , Zahn Jeffrey D.
Published: August 2009

A microfluidic biosensing assay has been designed and tested with streptavidin coated paramagnetic microbeads and fluorescently conjugated biotin (Biotin-FITC). The device is a three-inlet, three-outlet channel made by soft lithography of polydimethylsiloxane (PDMS). A novel magnetic actuation scheme is used to manipulate the beads within the channel. The device has proven capable of measuring the antigen concentration of a continuous sample stream. It is proposed that this technology could be applied as a real-time immunosensing assay.
Engineering Around the World: Driving Local Economics in Africa With Human Power
Authors: Cyders Timothy , Kremer Gregory G.
Published: August 2009

Engineering projects are a major proponent of development in impoverished areas throughout the world. Designers face difficulties when working on projects for unfamiliar cultures and infrastructure, from problem and constraint definition to final technology transfer. Through a design project and implementation trip, this study will examine the design process as it spans borders, cultures and languages, identifying key steps and methods in the process necessary for the success of such projects. One major problem many rural communities in developing nations experience is a lack of transportation infrastructure. Forms of transport common throughout the rest of the world are, in many cases, neither economically feasible nor locally sustainable. To establish basic infrastructure, a sustainable, affordable method of transporting goods and services is essential. This research project fulfilled this need by designing an appropriate local transportation solution, a human-powered utility vehicle (HPUV). To properly understand the problem, the researcher traveled to two different rural locations in Sub-Saharan Africa (Maase-Offinso, Ghana and Me`ri, Cameroon) on four different trips to gather information and customer input for the design of the HPUV. A final implementation involved traveling to Me`ri, Cameroon for three months during which one design prototype was built, tested and reviewed by local farmers and other end-users. The vehicle was tested quantitatively against metrics and specifications derived from initial assessment trips, as well as qualitatively through customer feedback. This direct feedback provides insight into the effectiveness of the machine and the design process followed, as well as identification of possible revisions to enhance the design’s value to those who need it. The design drawings and manufacturing plan are public-domain, and local mechanics in the village were taught the basic skills needed to produce the vehicle. The drawings and manufacturing plan were also presented to a local NGO capable of producing the vehicle using local labor.
Supply Chain Dynamics With Decision Making and Production Delays: Stability Analysis and Optimum Controller Selection
Authors: Delice Ismail Ilker , Sipahi Rifat
Published: August 2009

Delays in supply chains due to decision making (of managers) and lead time (in production) cause undesirable effects to inventory levels. Via system’s thinking, key mechanisms leading to such effects are investigated by analyzing the stability of an inventory, departing from a commonly studied model. On this model, two distinct delays and a PI controller to remove offset in inventory, are incorporated. On the plane of delays, stable and unstable operational behavior of inventory level are identified on so-called stability maps. Next, effects of PI controller to stability are revealed and this controller is optimized for avoiding oscillatory nature of inventory level. Case studies are provided to demonstrate counter-intuitive effects of delay presence to supply chain management and how stability maps may serve as decision-making tools for managers in achieving better control on inventory behavior.
Fabrication of Glass-Metal Composite Micro/Nanonozzles
Authors: Naik Nisarga N. , Allen Mark G.
Published: August 2009

This paper reports a fabrication technique for high strength glass-metal composite micro/nanonozzles with orifice diameters ranging from 430 nm to >100 μm. Unlike the conventional methods used to build micro/nanonozzles, the fabrication technique discussed in this paper is a non-lithographic approach. It uses conventional pulled borosilicate micropipettes as a foundation and nickel as a strengthening layer to build high pressure withstanding micro/nanonozzles. Pipettes built using the pulling process offer a smooth transition to the fluid from the reservoir to the tapered part of the nozzle, providing an ideal geometry from fluid flow and stress point of view. The nozzles are tested for high pressure withstanding capacity by integrating them with a high pressure fluidic setup to drive microjets. As an example, a 1.5 μm diameter nozzle, tested with propane as the working fluid to drive a microjet is observed to withstand pressures upto 10.5 MPa. Apart from simplicity of the fabrication process, this approach also offers the ability to incorporate a wireless temperature control system for the nozzles.
Diesel Engine Energy Balance Study Operating on Diesel and Biodiesel Fuels
Authors: Wallace Scott J. , Kremer Gregory G.
Published: August 2009

The use of alternative fuels is important to address the issues of reducing dependence on unstable petroleum supplies, and reducing harmful emissions that can lead to global warming. This paper focuses on a comparative energy balance on a four cylinder turbocharged diesel engine operating on diesel and biodiesel fuels. The diesel fuel tested was a standard No. 2 diesel fuel and the biodiesel used was 100 percent soy methyl ester (B100) supplied by Peter Cremer North America. Steady-state tests were run to experimentally determine how input energy in the form of fuel was appropriated throughout the engine. The transfer of energy was measured for losses to the engine coolant and exhaust, usable power output, as well as minor and unaccounted losses. Temperature measurements were taken using type-K thermocouples, the power and torque outputs were measured with an AE 250 eddy current dynamometer, and the fuel consumption rate was measured using a scale and digital stop watch. The coolant and air flow rates were also monitored with respective flow meters. The laboratory environment was monitored to insure operator safety as well as consistent operating and atmospheric conditions. An energy balance algorithm was constructed to analyze logged data from the experiments and insure that the proper amount of readings was taken to insure accurate results. The results showed that biodiesel and diesel fuel have almost the same energetic performance. The nominal values of the energy distribution showed that input energy from biodiesel was distributed 37.4%, 31.1%, and 29.6% to the major areas of coolant, exhaust, and power output, respectively. Similarly the input energy from diesel was distributed 37.5%, 31.4%, and 29.2% to the major areas of coolant, exhaust, and power output, respectively. The respective differences in those nominal values between the biodiesel and diesel fuel are −0.1%, −0.3%, and 0.4%. The uncertainty analysis showed that there was not a statistically significant difference in the energy distribution. The results also showed a strong correlation between the ambient air entering the engine and many of the other measured temperatures. Conclusions about the laboratory environment and testing procedures have been made from analysis of the collected data. The energy balance study outlined in this paper helped validate the overall engine diagnostic testing system. It also helped establish guidelines and procedures for future testing because this testing platform will be used for future work in performance and emissions testing of algal-based biodiesel which is the program’s overall goal.
Characterization of Piezoelectric Materials for Thermoacoustic Power Transduction
Authors: Wekin A. , Richards C. , Matveev K. , Anderson M.
Published: August 2009

In this work an experimental study of the performance of piezoelectric transducers for power production from a small-scale thermoacoustic engine is presented. Four piezoelectric samples are identified and characterized. These samples are tested on a variable acoustic driver and electrical power produced is measured. Finally, the samples are tested on four experimental thermoacoustic engines to verify the results from the acoustic setup. The maximum power produced is 177 μW from a closed thermoacoustic engine coupled to a 15mm PZT disk.
A Design Tool for Distributed Concept Development
Authors: Nordland Kate , Hensel Edward
Published: August 2009

This paper provides an overview of a database tool to support collaborative concept development in an asynchronous, distributed design environment. This paper will illustrate how an ideation method, such as as brainstorming, can be applied to a desired set of functions for a new design. The result of the brain-storming session for each articulated function can then be used in conjunction with a collaborative weighted voting tool to develop a rank-ordered morphological chart of the design space. A case study will be presented to illustrate how the information and knowledge generated in a prior working session by a design group can be introduced into a subsequent design session. The case study will illustrate how knowledge can be effectively transferred from one design project to the next, and preserve design intent over time.
Microfluidic Control of Insect Locomotor Activity
Authors: Chung Aram J. , Erickson David
Published: August 2009

This work describes the intimate fusion of microsystems and physiology though the partial implantation of a microfluidic device into living insects, Manduca Sexta moth. This effort is a critical component in our development of “Insect-Micro Air Vehicles (I-MAVs)” which aim to fuse nanodevice technology with living organism. The specific goal of this system is to provide “on-command” chemically induced immobilization and subsequent reanimation of the otherwise autonomous insect by implanting a low power electrokinetic drug delivery device. In this paper, we demonstrate the locomotor activity control by releasing neurotransmitters into wing muscles. We also provide results of our fully functioning adult survivability data for pupal stage implanted microdevices along with results from a comprehensive study of a low power electroactive drug delivery system.
The Effect of Electrical Conductivity on Pore Resistance and Electroporation
Authors: Li Jianbo , Lin Hao
Published: August 2009

Electroporation refers to the permeabilization of the cell membrane with one or multiple electric pulses. The reversible form of electroporation is widely applied for drug delivery, gene and cancer therapy, and stem cell research, among others; the irreversible form of electroporation is being explored for cancer treatment in a drug-free manner. In this work, an electroporation model is developed with particular focus on the prediction of pore resistance. The resulting formulation computes pore resistance as a function of pore size, and intracellular and extracellular conductivities, and avoids empirical or ad hoc specification of the conductivity of the pore-filling solution as practiced in previous works. Such a model is coupled at the whole cell level to investigate the effect of conductivity ratio on membrane permeabilization. The results reveal that the membrane achieves the maximum degree of permeabilization when the extracellular-to-intracellular conductivity ratio is around 0.5.