bluuebunny/crossref_metadata_2025 huggingface dataset:
Lead From Behind: Enabling Partnerships to Bring Clean Water to Caliche, Honduras
Authors: Doudican Brad , Elbin Wyatt , Huelskamp Bethany
Published: October 2013

The common model for engineers’ engagement in philanthropic development work is to find a community with a technical need, design the solution, raise funds for the solution, construct the solution, and hand the solution over to the community. While this approach has yielded many completed projects around the world, there are limits to the efficacy, sustainability, and long-term enabling potential to this approach. The Dayton Service Engineering Collaborative, or DSEC, takes an alternative approach to philanthropic community development which is demonstrated via a case study in bringing clean water for drinking and agricultural purposes to Caliche, Honduras.

Caliche, an impoverished village of approximately 350 people located in central Honduras, had access to a mountain spring as a source of water until a 2009 earthquake sent the spring’s flow underground. As of late 2011, the village did not have a clean source of drinking water, utilizing collected rainwater and surface water ponds for all of their water needs. Waterborne illness and malady was prevalent, with severe consequences to the young and the elderly. After a survey of the geography, the resources of the local people, and partner institutions, a community-scale biosand filtration system with requisite delivery structures was proposed, accepted, and brought to design fruition.

Design and implementation of a solution to the technical problem of water delivery and treatment, while rigorous and complex, is not out of the realm of practice for technical groups working in communities such as Caliche. The innovation in this project, however, was the “lead from behind” approach in the context of a best practice called asset-based community development. A multi-partner initiative led first and foremost by the community leadership, and through local institutions and power structures, was managed from distance. In addition to DSEC, partners in this project included a multi-national non-governmental organization (NGO), a financial investor, the Honduran government, several missionaries, the Caliche Water Council, a local landowner, the Caliche leadership known as the Patronado, and the local church. DSEC provided technical leadership and project oversight, ensuring that not only were the technical obstacles overcome, but that the community and local authorities were empowered to tackle future development projects with independent vision. It is through this enabling approach that impact beyond the immediate project is attained, and where DSEC believes the leadership potential of the engineer is fully realized.
Design and Analysis of a Wire-Driven Robot Tadpole
Authors: Li Zheng , Gao Wenqi , Du Ruxu , Liao Baofeng
Published: October 2013

Besides fish there are a lot of animals can swim effectively in the water, such as tadpole. Different from fishes using multiple fins to swim, tadpole has only one tail. It is well known that most fish employ the caudal fin to generate thrust, and use the pectoral fin, pelvic fin, etc. to balance the body and control its moving direction. However, the tadpole fulfilled all these tasks by the tail only. Hence, it is interesting to build a robot tadpole and study its motion. In this paper, a robot tadpole is designed. It has a blunt head and a tail. The control system, power supply and actuator are inside the head. The tail is a novel wire driven flapping propeller. The tail has a serpentine backbone with 7 joints, which are controlled by just one actuator. A prototype is built. The overall length of the robot tadpole is 328cm. Experiment results show that the robot tadpole can swim freely in the water. Its speed is affected by the flapping amplitude and frequency. In the experiments, the tadpole’s speed can reach 0.413 body length per second (BL/s), which matches the prediction from the propulsion model.
Introduction of Mass Points Into the Finite Element Method for the Dynamic Behavior Modeling of Rotating Machine
Authors: Dougdag Mourad , Ouali Mohammed
Published: October 2013

The dynamic modeling of the rotating machines system is required to understand their dynamic behavior and the associated vibration problems. Fortunately, this modeling has seen a great development, since the use of Timoshenko or Euler-Bernoulli beam, followed by the Jeffcott and Laval rotor until using fine and complex techniques these days.

Unfortunately, this development remains still insufficient to describe in a realistic way the dynamic behavior, in particular the rotor.

Nowadays, the using of the finite element method, which is considered as the powerful numerical tool, gave a great help. This method can model as real as possible the phenomena that influence the rotor behavior, but this tool remains inapplicable to describe its behavior when it undergoes at the same time motion, deformations and the faults effects.

To resolve these problems, a number of mathematical artifices are used, but, these methods are some times very difficult or are too complex and the result obtained is not always as good as it hopes. In fact, the deformed rotor resolution method is reduced to a modal solution, which does not show the real deformations during time in many cases.

In order to simplify the resolution and to show rotor movement with deformation under faults effects, a method is proposed to allow a better approach of this problem. This method is based on subdividing the structure to mass-point sections that make possible to consider the rotational motion with deformations of the rotors.

In this work, the above method is implemented on engineering simulation software dedicated for rotordynamics, and the calculation results are validated against experimental data of fault simulations in rotors as presented in the following sections of this paper.
A Numerical Study of the Convective Heat Transfer in Low-Reynolds Number Turbulent Flows in Corrugated Pipes
Authors: Rahmani Ramin K. , Arnold J. Eric , Kraus George W.
Published: October 2013

Enhancement of convective heat transfer in internal turbulent flows with low-to-moderate Re number has been the subject of numerous studies, due to its vast applications. Corrugated surfaces can be used as enhancement devices in the heat convection systems. An ideal corrugation, for heat transfer in internal flow applications, provides a higher heat transfer rate with minimized pressure drop. The ratio of heat flux to the pressure drop can be used to determine the efficiency of a design. Using Large-Eddy Simulation, the heat transfer in low-Re turbulent flow in a pipe is studied to investigate the impact of different corrugated profiles with similar hydraulic diameter.
Development of a Methodology for the Conversion of Truck Diesel Engines to Biogas Operation for Electricity Generation in Farm Zones of Colombia
Authors: Bermejo Fabio A. , Orozco Wilman A.
Published: October 2013

The introduction of mass transit systems in major cities of Colombia has led to several socio-economic impacts, arising from the market for diesel vehicles belonging to the public transport fleet in each city. The majority of diesel engines are sold a very low cost or are stored in the junkyards of the city’s industrial sector. This article proposes the development of a methodology for the remanufacture and transformation of these engines to an exclusive operation with biogas for use as a stationary source of electricity generation in rural areas. They are not connected to the country’s electricity network. This theoretical and experimental work is based on the implementation of specialized texts in the conversion of internal combustion engines to biogas, as applied to a Caterpillar 3126E diesel engine. Following completion of the study a conversion system was made to be installed in other types of Diesel engines. The instructions for this shows how to make the construction and operational changes to the engine, such as; decreasing the compression ratio, removing the Diesel injection system, adding ignition and feeding systems for Biogas. Also the engine was tested obtaining a maximum mechanical power of 63.4 kW (85 hp) and 211 N m (155.6 lb ft) of torque at 2800 rpm. The use of these engines in this application will reduce emissions of methane in the atmosphere, will help generate employment for the industrial sector and therefore contribute to the productive development of the country’s rural areas.
Application of Magnesium Oxide Functional Coating for Controlling the Corrosion of Magnesium for Implant Applications
Authors: Kotoka Rubenv , Worthy Ashlyn , Clinard Erica , Pai Devdas , Sankar Jag , Yarmolenko Sergey
Published: October 2013

Magnesium and its alloys are great candidates for uses in orthopedic implant applications due to their biocompatibility, mechanical properties and degradability. However, they are susceptible to accelerated degradation rates due to micro galvanic corrosion, which leads to unpredictable corrosion behavior. The poor corrosion resistance limitation restricts the practical use of Mg for implant application, where exposure to aggressive environment of body fluids is unavoidable. This paper describes the growth, characterization and corrosion analyses of MgO coatings which can slow down the degradation of Mg. Bilayer Mg-MgO system was prepared by pulse DC magnetron sputtering method and used as a model for evaluation of sustainability of MgO on Mg surface. Immersion tests were performed on Mg-MgO system with varying thicknesses using the optical density method. The tests were performed at room temperature and 37°C with deionized water, phosphate buffered saline, albumin, media, media with fetal bovine serum and saline solutions. The result showed that degradation rate of MgO on Mg substrate significantly depends on media.
Heat Transfer at Aluminum-Water Interfaces: Effect of Surface Roughness
Authors: Huang H. Sam , Wohlwend Jennifer L. , Varshney Vikas , Roy Ajit K.
Published: October 2013

In this paper, we studied the effect of microscopic surface roughness on heat transfer between aluminum and water by molecular dynamic (MD) simulations and macroscopic surface roughness on heat transfer between aluminum and water by finite element (FE) method. It was observed that as the microscopic scale surface roughness increased, the thermal boundary conductance increased. The thermal conductance increases 20% when the ratio of the amplitude of the surface roughness to the width of the system was changed from 0 to 1. At the macroscopic scale, different degrees of surface roughness were studied by finite element method. The heat transfer was observed to enhance as the surface roughness increases. The surface roughness was found to enhance the heat transfer both at the microscopic scale and at the macroscopic scale. Based upon the calculations at the microscopic scale by MD simulations and at the macroscopic scale by Finite Element method, a procedure was proposed to obtain the thermal conductance of surface roughness at the length scale of macroscopic and able to include the macroscopic scale surface roughness.
Hydrogen Airships: A Necessary Return Because of High Costs of Helium
Authors: Dumas Antonio , Trancossi Michele , Madonia Mauro
Published: October 2013

Many airship projects have been presented during last years. Most of them are slowed in their realization because of very high costs of Helium.

This paper presents an economic and energetic comparison between Helium filled airships and Hydrogen filled ones under the hypothesis of buying 20 MPa compressed Helium and local production of photovoltaic hydrogen by electrolysis.

The economic evaluation comprises the costs of PV plant for hydrogen production and docking and distribution systems for both gasses.

Analysis of uncertainty has been performed to evaluate economic parameters and payback time of the investments.
Acoustic Radiation Force Creep and Shear Wave Propagation Method for Elasticity Imaging
Authors: Amador Carolina , Urban Matthew W. , Chen Shigao , Greenleaf James F.
Published: October 2013

Elasticity imaging methods have been used to study tissue mechanical properties and have demonstrated that tissue elasticity changes with disease state. Quantitative mechanical properties can be measured in a model independent manner if both shear wave speed and attenuation are known. However, measuring shear wave speed attenuation is challenging in the field of elasticity imaging. Typically, only shear wave speed is measured and rheological models, such as Kelvin-Voigt, Maxwell and Standard Linear Solid, are used to solve for shear viscoelastic complex modulus. Acoustic radiation force has been used to study quasi-static viscoelastic properties of tissue during creep and relaxation conditions, however, as with shear wave propagation methods, a rheological model needs to be fit to the creep or relaxation experimental data to solve for viscoelastic parameters. This paper presents a method to quantify viscoelastic properties in a model-independent way by estimating complex shear elastic modulus over a wide frequency range using time-dependent creep response induced by acoustic radiation force. The acoustic radiation force induced creep (RFIC) method uses a conversion formula that is the analytic solution of the constitutive equation relating time dependent stress and time dependent strain. The RFIC method in combination with shear wave propagation is used to measure the complex shear modulus so that knowledge of the applied radiation force magnitude is not necessary. Numerical simulation of creep strain and compliance using the Kelvin-Voigt model shown that the conversion formula is sensitive to sampling frequency, the first reliable measure in time and the long term viscosity approximation. Experimental data are obtained in homogeneous tissue mimicking phantoms and excised swine kidneys.
Modeling of the Rotational Dynamics of a Flexible Manipulator Using FMBS to Derive a Linear Parameter Varying System
Authors: Knierim Karl Lukas , Gruhler Matthias , Sawodny Oliver
Published: October 2013

This paper deals with the derivation of the rotational dynamic matrix of a flexible large scale manipulator in the horizontal plane using the flexible multi body systems (FMBS) frame-work. It is shown, that the dynamic matrix only depends on the pose of the manipulator itself. The nonlinear dynamics of the FMBS system can be simplified and rewritten in the form of a linear parameter varying system, which can be used in the controller synthesis. The approach is exemplified at a large scale flexible link manipulator, with a range of approximately 13m, which is currently under development as a tool for ordnance and IED clearing.
Comparison of Numerical and Experimental Results of Small Scale Compressed Gas Blast Experiments Involving a Surrogate Head Form
Authors: Grimm Matthew V. , Muci-Küchler Karim H. , Hinz Brandon J. , Walsh Shawn M.
Published: October 2013

Exposure to a shock wave from an explosive blast can result in injury to the human body even if external signs of trauma are not present. Gaining a better understanding of the mechanisms contributing to those injuries can result in the design of better personal protective equipment (PPE). Compressed gas blast experiments can be conveniently used to explore the mechanical response of PPE systems and instrumented surrogate head forms to blast loading scenarios in a laboratory environment. Likewise, numerical simulations can be used to study relevant field variables related to the compressed gas blast and its effects on the target. In this regard, experimental data is needed to validate simulation results.

This paper presents an experiment that uses a small scale compressed gas blast generator to explore the pressure distribution around a surrogate head form due to blast loading. The compressed gas blast generator is an open-end shock tube which creates a shock wave when the diaphragm that separates the high pressure and low pressure (ambient air) regions ruptures. The overpressures on selected locations of the surrogate head form were measured with piezoelectric pressure sensors and the data was processed to obtain positive phase durations and positive phase impulses. The surrogate head form was positioned off-axis from the exit of the compressed gas blast generator to preclude the discharge flow from affecting the overpressure measurements. A three-dimensional Coupled Eulerian-Lagrangian (CEL) model of the experiment described above was prepared in Abaqus/Explicit. Selected numerical and experimental results were compared and there was good agreement between them.
Zero Emission Temporary Habitation: Analysis of a Passive Container Housing System Acclimatized by Geothermal Water
Authors: Dumas Antonio , Trancossi Michele , Madonia Mauro , Garziera Rinaldo , Piancastelli Luca , Pirondi Alessandro , Frizziero Leonardo
Published: October 2013

This paper presents a novel concept of container mobile housing system denominated ZETHa (Zero Energy Temporary Habitation). It is based on the LESP (Low Exergy Structured Panel) concept, in which the acclimatization is realized by water recirculation inside the external walls of the building and the ZEBRA concept (Zero Energy Consumption Building totally Renewable Addicted). A general plant and building design has been produced with the aim to minimize the presence of thermal bridges. The calculations of energy dispersion have been performed both in the wall and in the whole building. The energetic contribution of renewable energy plants has been evaluated to obtain a totally passive building. This evaluation will also consider energy needs by appliances.
Simulating the Thermal Response of Thin Films During Photonic Curing
Authors: Guillot Martin J. , McCool Steve C. , Schroder Kurt A.
Published: October 2013

A new technology utilizing short high-intensity pulsed xenon flashlamps has been termed “photonic curing”, and has become an efficient method for thermally processing thin film metal inks on inexpensive, low temperature substrates. For each film/substrate combination there is an optimum set of pulse conditions that will cure a given material stack most efficiently without damaging the substrate. The temperature distribution in the film stack is controlled by varying one or more of several pulse parameters such as peak intensity, pulse length, and frequency of pulse repetition. Given the large combination of possible pulse parameters and candidate materials, it is critical to be able to determine the set of pulse conditions that most efficiently cure the various possible combinations of candidate material stacks without damaging them. In this effort, a modeling tool is developed to simulate photonic curing. The model couples a transient 1-D heat conduction model to an intuitive graphical user interface, and contains a comprehensive materials database of temperature-dependent thermal and material properties for a large number of candidate film materials. The governing heat conduction equation is discretized using the finite volume method, including an algorithm to optimize mesh spacing and time stepping based on spatial and temporal temperature gradients. The simulation tool is validated using known analytical and semi-analytical solutions based on Green’s function solutions. It is then applied to a typical film stack used in photonic curing.
Correlation of Tensile Properties of Pressure Vessel Steels by Shear Punch and Small Punch Test Methods
Authors: Prakash Raghu V. , Ramesh T. , Raju N. , Suresh S.
Published: October 2013

A shear punch test is a very useful small specimen test method for evaluating the mechanical properties of in-service components, in view of the requirements of small size sample material. Typically disks of nominal size 10 mm diameter, having a thickness of 0.5 mm or less is used to extract the tensile properties through measurement of load-displacement responses. This paper presents the results of shear punch tests on pressure vessel steels and its correlation with yield stress and ultimate tensile stress obtained using ASTM standard specimens. Small punch test is similar to shear punch test, except that the indenter is spherical in shape, and as a consequence the material under the punch will be subjected to biaxial state of stress. The tensile response of materials derived by small punch test is correlated with standard tensile tests.
Laser Induced Nano-Droplet Ejection for the Construction of Nano-Inkjets
Authors: Yang Yu , Sundaram Vijay M. , Soni Alok , Wen Sy-Bor
Published: October 2013

To achieve precise nano-droplet ejection, the existing microscale inkjet module could be scaled down to nanoscale, including both the fluidic channel and the pressure driver. While 2D/3D nanoscale fluidic channels are currently available, a nanoscale pressure driver providing high enough power intensity to overcome surface tension for nano-droplet ejection is still lacking. In this study, laser induced nanoscale confined heating with nano-nozzles are constructed and demonstrated as a simple and robust approach to achieve the required pressure driver. For the heating with continuous laser, micro spray composed with nano-droplets can be induced from the nano-nozzles. For the heating with nanosecond laser of adequate pulse energy, drop-on-demand ejection of droplets with similar diameter as the apertures of the nano-nozzle can be achieved.
Case Studies and Online Training Used to Enhance Engineering Ethics at the Undergraduate and Graduate Level
Authors: Vlcek Brian L. , Haynes Eleanor
Published: October 2013

In a progressively materialistic and relativistic society, professional engineering ethics has become an increasingly important safeguard, but remains neglected in most formal engineering education. In response, at our university ethics content has been implemented and measured in both an undergraduate and graduate engineering course as a trial for further implementation across the university. In a senior-level seminar course, instructional emphasis was placed upon ethics in general, and engineering case studies readings reinforced with written responses were used to more effectively impart discipline specific knowledge. Other written activities such as current event articles and term papers with ethical content were implemented to promote higher level cognitive reasoning skills Students were surveyed at the end of the course and submitted work analyzed using a rubric to assess learning. On senior exit surveys, program graduates identified a 17.1 increase from 2009 to 2011 in their ability to understand professional, ethical and social responsibilities-this timeline was concurrent with the sited changes in the seminar course. For the graduates, emphasis was placed upon ethics with regards to research. An online series of training modules that meets the NSF minimum content as expressed by the COMPETES Act was used in the graduate course to supplement instructor lectures. In the case of the graduate learning experience, a pre and post training survey was conducted to determine changes in knowledge and understanding as a result of ethical training. On a pre-survey, forty-eight percent of the graduate students demonstrated a lack of understanding with regards to ethical issues relating to authorship. Fifty-two percent of graduate students pretested also incorrectly responded that a conflict of interest was always an issue of academic misconduct. These misconceptions were minimized by the end of the online training. Additionally, embedding profession ethics content into a senior-level seminar course has contributed significantly to satisfying our ABET learning outcomes and program objectives, while the graduate-level training has begun a fundamental change in the ethical culture of our graduate student researchers.
Investigation of Alternative Materials to Si for Solid State Micro Joints
Authors: Traisigkhachol Ornwasa , Pape Florian , Gatzen Hans H.
Published: October 2013

A joint’s function is to allow a relative motion between two components. While macroscopic joints typically use bearings or hinges to accomplish articulation, Micro Electro-mechanical Systems (MEMS) commonly take advantage of solid state joints, typically comprising bending or torsion beams. Micro joints made of NiW and the epoxy SU-8™ were fabricated by thin-film techniques and simulated in their usability as spring material. For determining the spring constant of the cantilever beams intended as solid state micro joints, a Hysitron TriboIndenter™ was used. It could be demonstrated that NiW represents a material well suited for sensitive solid state joints. Also SU-8™ as solid state joint was suitable to be applied as a cantilever. SU-8™ cantilevers can be used for higher displacements at greater loads.
A Numerical Study of Assisting and Opposing Mixed Convective Heat Transfer From a Horizontal Isothermal High Aspect Ratio Rectangular Cylinder
Authors: Oosthuizen Patrick H.
Published: October 2013

Mixed convective heat transfer from an isothermal cylinder with a rectangular cross-section and a relatively large height-to-width ratio has been numerically studied. The axis of the cylinder is horizontal with the longer sides of the rectangular cylinder being vertical. There is a vertical forced flow over the cylinder. The flow conditions considered are such that in general mixed forced and natural convective flow exists. Both the case where the buoyancy forces act in the same direction as the forced flow (assisting flow) and the case where they act in the opposite direction to the forced flow (opposing flow) have been considered. The flow has been assumed to be two-dimensional and the Boussinesq approximation has been adopted. Attention has been restricted to the flow of air and results have therefore been obtained for a Prandtl number of 0.74. The flow conditions considered are such that laminar or turbulent flow can exist. The main attention is this work has been directed at determining the effect of the flow parameters on the mean heat transfer rate from the cylinder and on determining the conditions under which the flow can be assumed to be forced convective and under which it can be assumed to be natural convective.
Numerical Simulation of Steady and Unsteady Compressible Multiphase Flows
Authors: Li Huiying , Vasquez Sergio A.
Published: October 2013

The present work concerns the development of an advanced numerical approach to simulate steady and unsteady compressible multiphase flows in the CFD solver FLUENT. Compressible multiphase flows can be simulated under the framework of either the multiphase Mixture/VOF or the Eulerian multifluid model. The governing equations solved are the mixture (Mixture or VOF model) or phase (Eulerian multifluid model) momentum, energy, species transport equations and phase volume fraction equations. Turbulence effects are accounted for using a range of multiphase turbulence models. For the compressible multiphase model, it assumes that only one phase is a compressible gas/gaseous mixture with multiple species. In gas-liquid flows, all the liquid phases can be compressible /incompressible liquid, while in gas-solid flows the solid phase can be treated as a granular flow. To ensure numerical stability and obtain physical solutions, the absolute pressure is limited in a way to satisfy the constraints for both incompressible and compressible flows that may exist in different regions. The compressible effects are taken into account by adding extra terms related to sound speed and phase volume fractions in both the phase volume fraction and the pressure-correction equations. For flow conditions at inlets and exits, only pressure and mass-flow-rate boundaries are applicable. The mixture Mach numbers are defined and used to determine the subsonic or supersonic flows and thermal boundary conditions.

The compressible multiphase model have been successfully used to simulate steady and unsteady, sub- and super-sonic compressible multiphase flows in a wide range of 2D and 3D multiphase systems. The examples presented in the paper include: (1). Gas-liquid separation in a vertical cylindrical container; (2). Transient pressure variations in compressible liquid and gas-liquid flows of water hammers; (3). Sub- and super-sonic gas-liquid two-phase flows in a nozzle; (4). Cavitating and ventilated super-cavitating flows; and (5). 3D gas-liquid flows in a three-stream injector. The solver robustness and convergence performance will be discussed. The solutions will be compared with available experimental data or numerical solutions. Emphasis will be focused on the solver performances on simulations of compressible multiphase flows. Overall, the results obtained from the present compressible multiphase model are in line with analytical/CFD solutions or available experimental data. The numerical approach is reasonably fast and robust, and suitable for practical compressible multiphase applications.
Thermoelectric Generators Embedded in Microelectronic Chip
Authors: Sullivan Owen , Mukhopadhyay Saibal , Kumar Satish
Published: October 2013

Thermoelectric generators (TEGs) can significantly improve the net power consumption and battery life of the mobile devices or high performance devices by generating power from the waste heat of these devices. Recent advancements show that the ultrathin thermoelectric devices can be fabricated and integrated within a microelectronic package. This paper first investigates the power generation by a single ultrathin TEG embedded within a micro-electronic package considering several key factors such as load resistance, chip heat flux, and proximity of the TEG to chip. We observe that the power generation from TEGs increases with increasing background heat flux on chip or when TEGs are moved closer to the chip. After the investigation of a single TEG, an array of embedded TEGs is considered in order to analyze the influence of multiple TEGs on total power generation and conversion efficiency. Increasing the number of TEGs from one to nine increase the useful power generation from 72.9 mW to 378.4 mW but decreases the average conversion efficiency from 0.47% to 0.32%. This suggests that average power generated per TEG gradually decrease from 72.9 mW to 42.0 mW when number of TEGs is increased from one to nine. However, the total useful power generated using nine TEGs is significant and emphasize the benefits of using embedded TEGs to reduce net power consumption in electronics packages.
A Biomechanical and Biochemical Synergy Study of Heart Valve Tissue
Authors: Huang Hsiao-Ying Shadow , Balhouse Brittany N. , Huang Siyao
Published: October 2013

The function of heart valves is to allow blood to flow through the heart smoothly and to prevent retrograde flow of blood. Previous studies have shown that the mechanical properties of heart valve tissues, microstructures of extracellular matrix, and collagen concentrations are the keys to the healthy heart valves and, therefore, are crucial to the development of viable tissue-engineered heart valve replacements. Therefore, this study investigates the relationship between these factors in native porcine aortic and pulmonary valves and provides insights to the healthy heart valves. Heart valve leaflets are prepared for biaxial stretching to obtain mechanical properties. The average collagen concentrations of heart valve leaflets are determined via an assay kit. The results indicate that aortic valves are stiffer than pulmonary valves macroscopically and stiffness varies more in the circumferential direction for the aortic valve than it does for the pulmonary valve. Microscopically, it is due to collagen fibers in aortic valves are more in alignment than ones in pulmonary valves, which are more randomly in direction. Collagen assay results show that collagen concentrations are higher in the edges of pulmonary valves than in aortic valves. The results also suggest the duration of extraction may have significant affects on the concentration results. This work provides quantified stress and strain environment within heart valve tissues to help further studies on how to treat heart valve disease and create more viable heart valve replacements.
Fracture Characterization of Adhesive Joints in Carbon/Epoxy Wind Turbine Blades
Authors: Hua Yi , Gu Linxia
Published: October 2013

The objective of this work is to predict the fracture behavior of adhesive joints in the 4-ply carbon/epoxy wind turbine blades through finite element method. The influence of through-thickness flaw in the adhesive layer was examined. The contour integral method was used for evaluating the stress intensity factors (SIF) at the flaw tips, while the strength of the joint was assessed through the crack initiation and propagation simulation. The effect of adhesive shear modulus has also been investigated. Results suggested that the maximum stress occurred at the adhesive-shell interface and increased stress levels were observed in the case of adhesive layer with flaw. It also highlighted distinct edge effects along the thickness of the adhesive joint. Compared to the perfect adhesive, the static strength of the adhesive joint with flaw remained unchanged. Large shear modulus of the adhesive diminished the strength of the adhesive joint with the increased SIF.
Operational Temperature Ranges in Pulsating Heat Pipes
Authors: Hansen Nick , Michna Gregory J.
Published: October 2013

The pulsating heat pipe (PHP), due to its ability to dissipate large amounts of heat and reduce temperature nonuniformity, is a promising technology for electronics cooling applications. In this work, the effect of the direction of change of heat dissipation rate in a PHP was explored. A quasi-steady state was approached by either increasing or reducing the evaporator heat input rate to a given level. It was found that instead of reaching a single steady-state evaporator temperature for a given heat input and condenser temperature, there is a range within which the evaporator temperature will fluctuate. Since most electronics cooling applications will have a non-steady heat removal requirement, understanding this phenomenon is of great importance for the design of PHP heat sinks.
Mixed Modes Fracture and Fatigue Evaluation for Lithium-Ion Batteries
Authors: Stamps Michael A. , Huang Hsiao-Ying Shadow
Published: October 2013

Lithium ion batteries have become a widely known commodity for satisfying the world’s mobile energy storage needs. But these needs are becoming increasingly important, especially in the transportation industry, as concern for rising oil prices and environmental impact from fossil fuels are pushing for deployment of more electric vehicles (EV) or plug in hybrid-electric vehicles (PHEV) and renewable energy sources. The objective of this research is to obtain a fundamental understanding of degradation mechanisms and rate-capacity loss in lithium-ion batteries through fracture mechanics and fatigue analysis approaches. In this study we follow empirical observations that mechanical stresses accumulate on electrode materials during the cycling process. Crack induced fracturing will then follow in the material which electrical contact surface area is degraded and over capacitance of the battery reduces. A fatigue analysis simulation is applied using ANSYS finite element software coupled with analytical models to alleviate these parameters that play the most pivotal roles in affecting the rate-capacity and cycle life of the lithium-ion battery. Our results have potential to provide new models and simulation tools for clarifying the interplay of structure mechanics and electrochemistry while offering an increased understanding of fatigue degradation mechanisms in rechargeable battery materials. These models can aid manufacturers in the optimization of battery materials to ensure longer electrochemical cycling life with high-rate capacity for improved consumer electronics, electric vehicles, and many other military or space applications.
Materials and Techniques for Reduction of Vibration Transmission in String Trimmers
Authors: Leifer Jack , Weisenburger Stephen J.
Published: October 2013

It has been well documented that over long periods of time, people who regularly operate hand tools powered by small internal-combustion engines can become affected by a debilitating set of clinically irreversible effects, collectively referred to as hand-arm vibration syndrome (HAVS). Although HAVS cannot be cured, the onset of the disorder can be delayed or, in fact, prevented, by restricting the duration of the exposure and/or the magnitude of the vibration transmitted from the tool to an operator’s hands and arms (per OSHA and similar standards). Measurements have confirmed that vibration components along all three tool coordinate directions (axial, radial and circumferential) are significant, but vary in amplitude and frequency content as a function of location. The challenge is to find passive approaches capable of filtering out the most harmful low frequency components simultaneously along all three directions that do not impede the use of the string trimmer. Preliminary results show that adding lightweight, low density (lodengraf) particles to the string trimmer along its shaft reduces the amplitude of the measured radial and axial acceleration components at the grip and the loop handle. However, when the perlite particles are added only to the loop handle, there is an increase in measured circumferential acceleration component at the grip, likely due to the additional weight asymmetry introduced.
Assessment of Free Surface/Submerged Vortical Flow Structures and Gas Entrainment at Pump Intakes Using RANS CFD
Authors: Pal S. , Rizhakov Andri , Kinzel M. , Knight Kelly J.
Published: October 2013

The assessment of liquid flow patterns forming due to a submerged pump intake, and its associated gas entrainment phenomena, need to be reliable and accurate for a number of design applications. The use of conservative correlations can lead to gross over-design or, inaccurate predictions in certain complex suction arrangements. Scale model testing often has scale effects which leads engineers to rely on other analysis methods. Simplified analyses can fail to correctly predict the vortical features near the suction intakes and associated gas entrainment, which may lead many applications to use Computational Fluid Dynamics (CFD) as a method for intake flow predictions. However, reliable assessment of gas entraining into a suction intake with high Reynolds number internal flow, involves several physical modeling and numerical challenges. An accurate assessment requires, (1) a transient model, (2) proper resolution in the wall boundary layers near the intakes, (3) resolution of the swirl in the vortical structures, and (4) modeling of the laminar-to-turbulent transitional effects in the vicinity of the intake. This paper addresses and evaluates the performance of several turbulence model options and modifications within a CFD code for the assessment of intake flow. The results presented in this paper, are compared against published experimental data on vortical flow patterns at intakes, to identify physical and numerical modeling needs for such assessments. The results show that while, adequately resolved meshes, and low Reynolds number RANS (Reynolds Averaged Navier Stokes) turbulence models can capture the location and relative strength of vortices, the results for flow details inside the vortical structures identified need to be interpreted carefully, considering the relevant flow physics and modeling limitations. The turbulence model modifications proposed involve curvature correction and scale adaptiveness.
Optimum Driving Control Based on Throttling Mechanism Design
Authors: Jawad Badih A. , Arslan Selin
Published: October 2013

The performance of a racing engine is most dependent on the control of airflow entering the air intake manifold. In order to improve drivability and throttle response, the throttle angle within the throttle body must be precisely tuned with engine airflow. The actuation motion must be set as a direct function of the accelerator pedal position if this direct relationship is to be achieved.

Many of the current throttling mechanisms are designed with a variable pedal-to-throttle response, meaning simply that a certain distance of pedal displacement does not necessarily result in a defined amount of throttle rotation. This setup, in most cases, is created by design in order to fit the type of vehicle being discussed. Known as brand DNA, this practice would, for instance, prescribe a smaller pedal-to-throttle ratio for a sports car than it would for a luxury car. This setup is acceptable for the common driver; however, in a racing situation a more precise relationship is needed.

The airflow through a standard automotive throttle body is not exactly proportional to the displacement of the accelerator pedal. Therefore, another method is needed to open the butterfly valve in order to ensure that airflow through the throttle body is metered equal to pedal displacement. This paper finds that the implementation of a cam-type pulley is necessary to achieve this prescribed goal.
Thermal Properties of Carbon and Graphite Foams
Authors: Patrick Melanie , Vital Amber , Bridges Darian , Saad Messiha
Published: October 2013

Thermal properties such as specific heat, thermal diffusivity, and thermal conductivity of carbon and graphite foams are very important in the engineering design process and analysis of aerospace vehicles as well as space systems. These properties are also important in power generation, transportation, and energy storage devices including fuel cells. Thermal conductivity is the property that determines the working temperature levels of the material; it plays a critical role in the performance of materials in high temperature applications and it is an important parameter in problems involving heat transfer and thermal structures.

The objective of this paper is to develop a thermal properties data base for carbon and graphite foams. Carbon foams are commercially produced from urethane, petroleum pitch-based and coal-based processes, and they typically have large pores (> 350 μm) and low density (< 1.0 g/cm3). Petroleum pitch-base and coal-base carbon/graphite foams can be tailored to be thermally conductive or thermally insulating.

The thermophysical properties of carbon and graphite foams have been investigated using experimental methods. The flash method was used to measure the thermal diffusivity of the foams; this method is based on America Society for Testing and Materials standard (ASTM E1461). In addition, the Differential Scanning Calorimeter was used in accordance with the ASTM E1269 standard to measure the specific heat. The measured thermal diffusivity, specific heat, and density data were used to compute the thermal conductivity of the foams.
Laser Absorption Spectroscopy Tomography Beam Arrangement Optimization Using Resolution Matrices
Authors: Twynstra M. G. , Daun K. J.
Published: October 2013

Laser-absorption tomography experiments infer the concentration distribution of a gas species from the attenuation of lasers transecting the flow field. Although reconstruction accuracy strongly depends on the layout of optical components, to date experimentalists have had no way to predict the performance of a given beam arrangement. This paper shows how the mathematical properties of the coefficient matrix are related to the information content of the attenuation data, which, in turn, forms a basis for a beam arrangement design algorithm that minimizes the reliance on additional assumed information about the concentration distribution and thus increases reconstruction accuracy. The performance of this algorithm is assessed by comparing the reconstruction error obtained from an optimized beam arrangement to that obtained from beam arrangements presented in the literature.
The Effects of Machining Induced Damage on Flexural Strength of Low Density Carbon Foam
Authors: O’Connor A. , Ramulu M.
Published: October 2013

An experimental investigation was conducted in order to evaluate the edge finishing and damage effects on the transverse rupture strength (TRS) of non-graphitic carbon foam. Machining tests were conducted on Carbon Foam using an end milling process employing diamond abrasive (DA) and polycrystalline diamond (PCD) cutting tools. The surface roughness and damage induced during machining was measured using surface profilometry and scanning electron microscopy respectively. Four-point bending tests were conducted in order to determine the TRS. It was found that the damage induced during the machining of the samples had no significant effect on the transverse rupture strength of the material within the experimental conditions. The measured flexural strength was found to be 2.38 MPa and 2.25 MPa for PCD and DA machined conditions respectively. Machining induce micro-damage including micro-cracking was estimated to be 25–75μm in length. The measured average cell diameter was found to be 1120μm. The induced micro-chipping and cracking is negligibly small when compared to the cell diameter and therefore does not contribute to any stress concentration or reduction in residual strength. This research demonstrates the material’s natural geometric features which are believed to dominate the damage tolerance behavior.
Anti-Limb Entrapment Insert
Authors: Barnett Ralph L.
Published: October 2013

Access to the suction pipe in a main drain can occur whenever the sump cover is unfastened, broken, or missing. An arm or leg can be placed, sucked, or propelled into the pipe where the limb can be trapped by various mechanisms including suction, wedging, and tissue swelling. Although their success rate is unimpressive, there are a number of mitigation strategies for limb entrapment that are based on reduced pressure differential. These strategies are thoroughly examined in this paper. None of these compare however to the classic notion of preventing entrapment in the first instance. Restricting the pipe opening to small apertures through the use of permanent cross-members eliminates the limb entrapment hazard. Unfortunately, the cross-member solution used, for example, in tubs and slop sinks introduces new hazards that were not present in the open pipe; hair entrapment, finger entrapment, and mechanical entrapment (e.g. swimwear). This paper introduces a pipe insert at the entrance to the pipe that uses permanent fins to provide anti-limb entrapment. The fins are designed with an iso-friction profile to shed hair that may be entrained into the pipe. The equation for the profile is obtained in polar coordinates. The geometry of the fins minimizes finger and mechanical entrapment. Scallops are included around the edge of the pipe that inhibits body entrapment which can restrain a child with a suction force of 50 to 100 lbf (222 to 445 N). The use of an anti-limb entrapment insert together with a retrofittable anti-evisceration ring will achieve the same entrapment protection with or without a sump cover.
Thermal Performance of High-Flow Single-Phase Liquid-Cooled Heat Sinks
Authors: Akhmadullin Ildar F. , Manteufel Randall D. , Greene Christopher
Published: October 2013

Experimental measurements are reported for high-flow liquid-cooled heat sinks designed for cooling electronics components such as a CPU. The flow rate is up to 2 GPM with internal flow passage length scales on the order of 0.1 to 1.0 mm in the primary heat transfer region. Of the designs tested, three achieved maximum flow rates with pressure drops of less than 1.5 psi. Two have lower maximum flow rates because of higher internal flow resistance. In the experiments, particular attention is given to sources of experimental uncertainty and the propagation of uncertainty through the calculations to reported thermal resistance, R (°C/W). Analysis includes bias and precision errors for direct measurement of temperature, flow rate, and pressure drop. Additionally, a separate thermocouple calibration test is reported to establish measurement uncertainties for the system. Main emphasis is made to the error propagation in thermal resistance calculations of each heat sink and measurement of heat removal rate from the CPU. Data is used to determine the standard error for R which ranges up to about 0.05 °C/W with the maximum for one heat sink up to 0.07 °C/W. Averaging of repeated measurements at the same flow rate without accounting for the range of the original data will result in lower uncertainties in the reported results.