bluuebunny/crossref_metadata_2025 huggingface dataset:
Inertial Sensor Dynamics, Selection and Applications for Epileptic Seizure Detection
Authors: Kamalizonouzi Babak , Asokanthan Samuel F.
Published: October 2013

In this work, an optimal placement strategy for wearable inertial sensor placement on a human arm is presented with an ultimate goal of using a sensor cluster for epileptic seizure detection. The present study shows that the placement of sensors plays a significant role in achieving high sensing resolution. Employing the commercial package Motion Genesis™, a procedure is first developed to simulate the dynamic response when human body is under typical epileptic seizure episodes. The method uses Kane’s method to obtain equations of motion and the resulting equations of motion are numerically solved using Matlab™ when the system is subjected to a prescribed seizure input. Simulation results give insights into influences of the neurological disorder on sensing in quantitative terms. Based on certain assumptions on the predicted quantitative measures of the response, optimal detection performance based on sensor location and number of sensors is proposed with particular emphasis on sensor resolution and noise. The optimization is carried out employing the genetic algorithm module of Matlab global optimization toolbox to find the optimal placement of sensors to achieve least sensing noise in calculating the angular acceleration. The results are also verified with those predicted via simulated annealing. The predictions have also been validated via suitable sensitivity analysis to evaluate the efficacy of the method to uncertainties in the biomechanical, geometry as well as sensor noise parameters. The proposed optimal placement predictions are envisaged to be instrumental for the implementation of a wearable inertial sensor cluster.
Shear Wave Propagation of the Ferret Brain at Multiple Frequencies In Vivo
Authors: Feng Yuan , Chang Yulin , Clayton Erik H. , Okamoto Ruth J. , Bayly Philip V.
Published: October 2013

Mathematical modeling and computer simulations are widely used for understanding traumatic brain injury (TBI). However, accurate tissue parameters are needed, especially for the brain in vivo. In this study, we used the ferret as the animal model because it is the smallest mammal with a folded brain and significant white matter tracts. Magnetic resonance elastography (MRE) has proven useful for in vivo measurement of biological tissue properties. Mechanical properties of the ferret brain over a range of frequencies from 400–800 Hz were studied using MRE. Experiment results show both that storage and loss modulus increases with frequency and that dissipative effects in the white matter (characterized by the loss modulus G″) were significant larger than in gray matter.
Experimental Analysis of Thermal Energy Deburring Process by Design of Experiment
Authors: Fritz Ashley , Sekol Lisa , Koroskenyi Jim , Walch Bill , Minear Jeff , Fernandez Vernon , Liu Liping
Published: October 2013

The present work aims to conduct an experimental study through Design of Experiment (DOE) to develop a better understanding of the important variables and their impact during the Thermal Energy Method deburring process. The designed experiment was based on an L9 orthogonal array using Taguchi method and tests were conducted with an S-250 Kennametal-Extrude Hone machine. The variables tested were the chamber pressure, fuel to oxygen ratio, burr thickness and material type of the specimen. Based on variance analysis, the chamber pressure was found to have the largest variance value and was therefore concluded to have the largest impact on the deburring process. A linear regression model was developed from the experiment which can help predict the deburring outcome based on various input parameters.
Design and Rapid Fabrication of Customised Ear Prosthesis: A Case Study in Biomedical Engineering
Authors: Medellín Castillo Hugo I. , Méndez Ruiz Verónica
Published: October 2013

There are different methods to fabricate a facial prosthesis; the most common is the craftsmanship technique, which depends on the time, experience and skill of the surgeon. Although effective, it is an expensive method in terms of time and cost, and the precision of the prosthesis is limited to the manual sculpting skill of the surgeon. However, modern design and manufacturing technologies in engineering are increasingly being used in biomedical engineering applications such as prosthesis and implant design, surgical planning and tissue engineering. These modern engineering technologies have led to the enhancement of traditional medical methods in terms of accuracy, time, cost, resources and safety.

In order to enhance the conventional craftsmanship technique used in the fabrication of facial prosthesis, this paper presents a new approach to design and manufacture customized ear prosthesis based on Reverse Engineering (RE) and Rapid Prototyping (RP) technologies. A case study is introduced and developed along paper. The ear prosthesis is designed using RE and Computer Aided Design (CAD). Fabrication of the prosthesis is carried out by RP and lost-wax casting. The results are presented and compared with the traditional craftsmanship technique. Advantages and disadvantages of using modern design and manufacture engineering techniques are identified and discussed.
Material Characterization of Rubberized Aramid for Shock Mitigation
Authors: Thota Jagadeep , Saadeh Mohammed , Trabia Mohamed B. , O’Toole Brendan , Lee Chang-Hyun , Woo Kwan-Je , Park Hong-Lae , Lee Kang-Wun , Koo Man-Hoi , Lee Kyoung-Hoon
Published: October 2013

Modern military vehicles can reduce transmitted shocks to critical components within it through the use of composite armor and rubberized material at the space frame joints. Therefore, proper material models of these shock absorbing materials are imperative to accurately understand shock transmission. While quasi-static mechanical characteristics of candidate materials may be well understood, their behavior under dynamic conditions has not been studied as much. This research presents the mechanical characterization of rubberized aramid, which is used as a part of a composite armor. Since the rubberized aramid material may be subjected to large deformations due to the high impact loading, a strain-sensitive material model is proposed to describe this material computationally. Tensile tests on rubberized aramid are conducted under various strain rates. Additionally, dynamic mechanical analysis (DMA) vibration tests are conducted to determine the damping property of the rubberized aramid material. These measured characteristics can be incorporated in the material models that will be used in the computational analysis of the armored vehicle under shock loading.
Power Grid System Design Optimization Considering Renewable Energy Strategies and Environmental Impact
Authors: Piacenza Joseph , Tumer Irem Y. , Hoyle Christopher , Fields John
Published: October 2013

The North American power grid is a highly heterogeneous and dispersed complex system that has been constructed ad-hoc over the past century. Large-scale propagating system failures remain constant over the past 30 years as the rising population and affiliated energy centric culture continues to drive increases in energy demand. In addition, there are continued negative effects from various types of energy generation strategies, including renewables, on the environment. This paper presents a methodology for a high-level system optimization of a power grid capturing annual cost, energy use, and environmental impact for use during the early design trade studies. A model has been created to explore the system state of a power grid based on various types of energy generation, including both fossil fuel and renewable strategies. In addition, energy conservation practices for commercial and residential applications are explored as an alternative solution to meet predicted demand. A component for incorporating design trades within the model has been developed to analyze the feasibility of trading surplus energy between interconnections as a means to address issues with excess generation and mitigate the need for additional generation. The result is a set of Pareto Optimal solutions considering both cost and environmental impact that meet predicted energy demand constraints.
Comparison of Closed Chain Mechanisms for Positional Deviations
Authors: Jawale H. P. , Thorat H. T.
Published: October 2013

Closed Chain Mechanisms are popular in Automation Technology for transmitting motion under specific objective task. Single-Degree of Freedom (DoF) Four-bar chain is basic mechanisms synthesized for such applications. Joint clearances and drive backlash are inevitable in such mechanisms and introduce error in coupler positions while accomplishing the task.

The present paper considers effect of joint clearances and drive backlash as error source for coupler positions in single-DoF mechanism. The deviations of desired positions and actual positions are estimated for specific objective task. Further, effect of these error sources is modelled with a higher-DoF mechanism which is kinematically better than single-DoF mechanisms. Two-DoF mechanism is modelled for identical objective task. Maximum positional deviations are estimated for two-DoF mechanism. The comparative analysis of deviation is obtained. Relative maximum positional deviation in both mechanisms is expressed in terms of dimensionless number as measure of performance.
Experimental Investigations of the Film Cooling Performance of a Micro-Tangential-Jet Scheme on a Gas Turbine Vane: Part 1 — Effectiveness
Authors: Hassan O. , Hassan I.
Published: October 2013

This paper presents experimental investigations of the film cooling effectiveness performance of a Micro-Tangential-Jet (MTJ) Film cooling scheme on a gas turbine vane using transient Thermochromic Liquid Crystal (TLC) technique. The MTJ scheme is a micro-shaped scheme designed so that the secondary jet is supplied tangentially to the vane surface. The scheme combines the benefits of micro jets and tangential injection. The film cooling performance of one row of holes on both pressure and suction sides were investigated at a blowing ratio ranging from 0.5 to 1.5 on the pressure side and 0.25 to 0.625 on the suction side. The average density ratio during the investigations was 0.93, and the Reynolds Number was 1.4E+5, based on the free stream velocity and the main duct hydraulic diameter. The pitch to diameter ratio of the cooling holes is 5 on the pressure side and 6.5 on the suction side. The turbulence intensity during all investigations was 8.5%. Minor changes in the Mach number distribution around the airfoil surface were observed due to the presence of the MTJ scheme, compared with the case with no MTJ scheme. The investigations showed great film cooling performance for the MTJ scheme, high effectiveness values, and excellent lateral jet spreading. A 2-D coolant film was observed in the results, which is a characteristic of the continuous slot schemes only. The presence of this 2-D film layer helps minimize the rate of mixing between the main and coolant streams and provides uniform thermal loads on the surface. Furthermore, it was noticed that the rate of effectiveness decay on the suction side was less than that on the pressure side, while the lateral jet spreading on the pressure side was better than that of the suction side. The main disadvantage of the MTJ scheme is the increased pressure drop.
Experimental Analysis and FEA of Friction Stir Welding on Aluminium Plates
Authors: Ledesma Elias , Aguilera Eduardo , Villalobos Gilberto
Published: October 2013

An experimental study and a numerical simulation of friction stir welding (FSW) process on aluminum 6064 plates is presented. The numerical analysis is performed using finite element technique with LsDyna software and the Aleatory Lagrangian Eulerian (ALE) formulation. Input parameters on the FEM are the mechanical properties of the aluminum 6064 as workpiece and H13 steel properties as the tool. The finite element analysis results shown Von Mises stresses and plastic strain developed during the process. An experimental analysis was conducted with the variation of process parameters and the specimens obtained were evaluated by x-ray inspection, tensile tests, and hardness measurements.
Spatial Four-Bar Motion Generation With Static Control Condition
Authors: Al-Smadi Yahia M. , Awad Omar
Published: October 2013

In conventional motion generation, the objective is to calculate the mechanism parameters required to achieve or approximate a set of prescribed rigid-body poses. This mechanism design objective is particularly useful when the rigid-body must achieve a specific displacement sequence for effective operation. A spatial four-bar motion generation model that also includes static structural conditions is formulated and demonstrated in this work. Using RRSS mechanism, spatial four-bar motion generators are synthesized with respect to static torque.
Nonlinear FEA Simulation of Thorax Considering Transient CPR Forces and Sternotomy
Authors: Awad Omar , Harfoush Mohamed , Al-Smadi Yahia M.
Published: October 2013

The median sternotomy has become the desired incision in the modern era of cardiac surgery. The objective of this study is to investigate the sternum loading due to daily forces after sternotomy and during healing. Two models of thorax were built. The first is to simulate the healthy thorax and the second is to simulate the thorax after sternotomy and got closure using stainless steel stitches. In this paper, ANSYS was used to build the throax model. The results that have been collected after solving the model were analyzed. The analysis was promising and proved that the model was working properly and its ability to simulation what happens in the real life.
An Integrated Approach for the Predictions of the Workpiece Vibrations During Machining of Aerospace Structure: Numerical and Experimental Validation
Authors: Meshreki Mouhab , Kövecses József , Attia Helmi
Published: October 2013

Accurate predictions of the workpiece vibrations during high speed machining of aerospace structural components is a critical issue since it affects the accuracy of the final part. For fixture design purposes, and for force predictions, the computational efficiency of the dynamic models predicting the workpiece vibrations is a crucial factor since it affects the cycle time for the design and optimization of the fixtures. Most of the available dynamic models are based on computationally prohibitive techniques, such as finite element analysis. In this work, an integrated approach, based on recently developed semi-analytical models, is presented for the analysis of the effect of the fixture layout on the dynamics of thin-walled structures while taking into account the continuous change of thickness of the workpiece, and the effect of rigid and deformable fixture supports. The developed approach is based on plate models with holonomic constraints and finite stiffness springs. This approach, together with all the developed models and formulations are validated numerically for different workpiece geometries and various types of loading. An experimental study has been performed to validate this approach through the machining of thin-walled components. It was found that this approach led to prediction errors within 10% and more than 20 times reduction in the computation time. The challenge of filtering the effect of the dynamics of the force measurement system from the measured signals was overcome by developing a new hybrid semi-analytical methodology for accurate measurement of the machining forces.
Impact Behavior of Liquid Crystalline Polymers
Authors: Saigal Anil , Ward Dan , Zimmerman Michael A.
Published: October 2013

Liquid crystalline polymers have the advantage of achieving desirable mechanical properties at a competitive cost. They are composed of molecular chains that are highly oriented and tightly packed at temperatures above and below its melting point. This high degree of orientation has the following advantages: ease of processing, high mechanical strength at extreme temperatures, and resistance to mostly all chemicals, weathering, radiation, and burning.

On the other hand, this high degree of orientation causes liquid crystalline polymers to have low impact strength as well as an uneven amount of shrinkage prior to molding. The objective of this study is to determine the effects of injection-molding parameters on the impact behavior of liquid crystalline polymers, in an attempt to improve and understand the processing of the material. The conditions to be tested are as follows: fill speed, initial mold temperature, and packing pressure.

The impact tester used for this research was an Instron Dynatup tester. Based on the data, it is apparent that fill speed is the greatest determining factor for optimizing the impact energy of the injection-molded liquid crystalline polymers followed by high packing pressure. In addition, even though the nature of the impact energy curves for LCPs and materials such as Delrin are similar, the impact load curves as a function of time are significantly different. This can be attributed to the layered structure of LCP samples.
Design Enhancement of the CANDU Spent Fuel Storage Basket
Authors: Choi Woo-Seok , Jeon Jae-Eon , Seo Ki-Seog , Lee Ju-Chan
Published: October 2013

The necessity of a demonstration test to evaluate the structural integrity of a basket for accident conditions arose during the license approval procedure for the WSPP’s dry storage facility, called MACSTOR/KN-400. A drop test facility for a demonstration was constructed at the KAERI (Korea Atomic Energy Research Institute) site, and demonstration tests for a basket drop were conducted. As the upper welding region of the loaded basket collided with the dropping basket during the drop test, the welding in this region was fractured and a leakage occurred after the drop test. An enhancement of the basket design is needed since the existing basket design was not able to satisfy the performance requirement. The directions for the design modification were determined and six enhanced designs were derived based on these directions. Structural analyses and specimen tests for each enhanced design were conducted. By evaluating the structural analysis and test results, one among six enhanced designs was decided as a final design for revision. The final design was the one that reduced the height of the central post of the basket and decreased the impact velocity with the dropping basket. Test basket models were fabricated in accordance with the final enhanced design. An additional demonstration test was performed for this test model and all the performance requirements were satisfied.
Optimum NURBS Curve Fitting for Geometry Parameterization of Gas Turbine Blades’ Sections: Part I — Evolutionary Optimization Techniques
Authors: Safari A. , Lemu H. G.
Published: October 2013

This paper presents two evolutionary optimization methods: Genetic Algorithm and Differential Evolution, aimed at optimizing the location of a set of NURBS control points that are used to calculate the NURBS points for leading edge, trailing edge, suction side and pressure side of an airfoil shape. The approach is illustrated on point cloud of several 2D sections of a typical gas turbine compressor blade, so that the results can be used for both reverse engineering purposes and geometry parameterization in airfoil aerodynamic shape optimization process. The optimization algorithms in this research are based on minimization of an analytical error function related to the distance between the fitted curve and original data points. Finally, the obtained results from these two techniques are compared with each other to distinguish the advantages and disadvantages of each method for such curve fitting problems.
Optimum NURBS Curve Fitting for Geometry Parameterization of Gas Turbine Blades’ Sections: Part II — Swarm Intelligence Techniques
Authors: Safari A. , Lemu H. G.
Published: October 2013

In part I of this study an optimum NURBS curve fitting by two evolutionary optimization techniques was successfully designed. These methods were implemented to optimize the location of a set of NURBS control points for the measured point cloud of four segments of a gas turbine compressor airfoil shape. The purpose of the optimization was to demonstrate the good ability of evolutionary techniques, in particular Genetic Algorithms, in optimizing such curve fitting problems. The objective of part II is to examine two alternative solutions for NURBS curve fitting of the same airfoil point cloud with swarm intelligence optimization technique. Indeed, the same work has been done by applying two basically different optimization approaches that is Particle Swarm Optimization and Invasive Weed Optimization. Results allow seeing a number of advantages as well as some disadvantages in this optimum curve fitting approach in comparison to the previous techniques applied by authors.
Physical Property and Carbon Black Distribution Impact on Propulsion Efficiency of Paraffin-Based Fuel
Authors: Santos Genivaldo P. , Pedreira Shirley M. , Lacava Pedro T.
Published: October 2013

In the last decade the hybrid propulsion has been considering as a viable alternative of chemical energy conversion stored in propellants into kinetic energy. This energy is applied in propulsive systems of manned platforms, maneuvering procedures and even in the repositioning process of micro satellites. It is a system of minimum environmental impact and lower cost than traditional systems based on liquid or solid propellants. Paraffin based grains are the hybrid solid fuels appointed as polymeric fuel substitute. The liquid layer formed on the burning surface ensures high regression rate when driven into the flame front. Paraffin grains allow row material recovery and reduce the risk of explosion in the presence of erosive burning. The structure of the grain and the control of the liquefying burning surface layer depend on the additives concentration, such as carbon black, which are added to the fuel matrix during the production process. In the solid propellant paraffin based grain a cylindrical center port developed during the centrifugation tends to concentrate carbon black in the outer region of the grain. During solidification 15% of shrinkage occurs and appears hardness gradient in the longitudinal and transverse directions. The influence of carbon black distribution and hardness gradient in paraffin based grain were evaluated in this work. The study suggests that multiple thin layers grain may generate burning surfaces with hardness and carbon black concentration almost constant. The ballistic properties and propulsion efficiency of a hybrid lab rocket scale with 150 N of thrust were evaluated in the pressure of 2.8 MPa with 140 Kg/(sm2) gaseous oxygen (GOX) mass flux, the results show up the nozzle operation and motor-propellant relationships.
A Numerical Model of Mechanics of Osteoarthritis in Human Knee Joint
Authors: Dabiri Yaghoub , Li LePing
Published: October 2013

Articular cartilage is composed of water entrapped in a solid matrix formed by proteoglycans and collagen fibers. Therefore, the mechanical behavior of this tissue is determined by all of these three components. In addition, the properties of articular cartilage vary along the depth and by location. In the human knee joint, the three dimensional geometry as well as the contact between the cartilaginous tissues plays essential roles in the joint mechanics. On the other hand, initiation and progression of osteoarthritis (OA) could be partly caused by contact loads. Consequently, the fibrillar and non-fibrillar matrices, the three dimensional geometry and the contact between the tissues should be considered as essential parameters in the study of the mechanics of osteoarthritis. However, previous studies on OA mechanics were mostly limited to explants geometries [1]. Also, the contact mechanics associated with the fluid pressure have not been considered in the previous OA models. In a recent knee model, fluid was considered in femoral cartilage but not in the menisci [2]. Additionally, the depth-dependent mechanical properties were not included in that model.
CFD Analysis of an Isolated Main Helicopter Rotor for a Hovering Flight at Varying RPM
Authors: Pandey K. M. , Kumar U. , Kumar Gaurav , Deka Dhrubajyoti , Das Dipankar , Surana Anand
Published: October 2013

The main objective of this simulation is to analyze the flow around an isolated main helicopter rotor at various main rotor speed of 800 RPM, 600 RPM and 400 RPM at an angle of attack of 8 degrees using blades of the Eurocopter AS350B3, which uses the blade profile of standard ONERA OA209 airfoil during hovering flight conditions. The comparison of the stability in terms of wake formations and vorticity has been included to visualize an optimum RPM for hovering of the helicopter mentioned. For the computational fluid dynamic (CFD) analysis, the moving reference frame (MRF) method with the standard viscous k-ε turbulent flow model was used for modeling the rotating rotor operating in a hovering flight condition.
Optimum Design of High-Speed 4-Bar Mechanisms Using a Bi-Level Game Theoretic Approach
Authors: Ghotbi Ehsan , Dhingra Anoop K.
Published: October 2013

This paper considers the design of a high speed mechanism as a multi objective optimization problem wherein the kinematic and dynamic criteria are optimized simultaneously. The kinematic criteria include minimization of the structural error and a minimization of deviation of the transmission angle from its ideal value. The dynamic criteria include minimization of input driving torque and shaking forces transmitted to the ground link. A Stackelberg (leader-follower) game theoretic approach is proposed to solve the multiobjective problem. Two variants, wherein both the kinematic and the dynamic criteria are treated as the leader, are considered. The design variables include mechanism dimensions and counterweight parameters. A partitioning of the design variables amongst the leader and follower objective functions is discussed. A computational procedure using sensitivity information is used for approximating rational reaction sets needed for capturing exchange of information between the leader and the follower problems. A numerical example dealing with the design of a path generating 4-bar mechanism is presented.
The Role of Protein as a Deformation Controller in Cellulose Tissue
Authors: Kato Yoko
Published: October 2013

The tunic of Halocynthia roretzi is composed of cellulose Iβ, mostly in crystalline form. It was recently revealed that the tunic can actively deform in response to mechanical stimuli and acetylcholine and that the tunic has F-actin, elastic fibers, acetylcholinesterase, and neurofilaments, which are involved in this process. Most of the hemocytes in the tunic secrete an enzyme whose substrate is the same as that of α-chymotrypsin; however, the enzyme’s role has not yet been determined. In this study, it was hypothesized that the enzyme hydrolyzes the protein in the tunic to induce tunic deformation. The results show that administration of α-chymotrypsin results in deformation of the tunic in an inward direction. Tunic deformation can be induced by the secretion of hemocytes due to greater hydrolysis of protein in the inner rather than outer regions. The deformation pattern is the same as that induced by both mechanical stimuli and acetylcholine. Moreover, stimulation with an electrical field (3.4 × 102 V/m), which is too weak to deform cellulose, still causes tunic deformation, indicating involvement of the nervous system. These characteristics will be helpful for the design of an active composite material containing cellulose.
Modification of the Interface in Carbon Nanotube-Grafted T-Glass Fiber
Authors: Kawada H. , Sato S. , Kameya M.
Published: October 2013

In recent years, carbon nanotubes (CNTs) have attracted a lot of interest as an additional component in fiber reinforced plastics (FRP) to improve the properties of the fiber/matrix interface. An improvement of the apparent interfacial shear strength (ISS) was achieved by grafting CNTs onto reinforcement fibers instead of dispersing CNTs in the matrix. In one study, composites containing CNT-grafted fibers and epoxy resin demonstrated 26% ISS improvement over the baseline composites. However, few studies are focused on glass fibers, due to their low heat resistance.

In this study, the effects of grafting CNTs onto T-glass fibers were evaluated by investigating the mechanical and interfacial properties of the CNT-grafted fiber/epoxy resin model composites. Elastic shear-lag analysis was also used to investigate the effect of CNTs on ISS.

We used the chemical vapor deposition (CVD) method to graft CNTs onto T-glass fibers. As a result, CNTs were grafted relatively uniformly and cylindrically onto the fibers, which indicates that the CNT-grafting process was appropriate.

The CNT-grafted fiber/epoxy resin model composites showed a significant (46∼67%) increase of interfacial shear strength. The formation of an interfacial region containing CNTs was observed around each fiber. Elastic shear-lag analysis showed a 20% increase of ISS. Those results imply that the elastic modulus of the interfacial region around the fibers was higher than that of epoxy resin.
Simplified Interior Ballistics Analysis of a Hybrid Projectile Prototype
Authors: Jackson Edward , Wilhelm Jay , Browning Patrick H. , Mucino Victor , Gautam Mridul
Published: October 2013

Structural analysis is a critical aspect in the successful design of tube launched projectiles, such as mortar rounds. Ongoing research conducted at West Virginia University has focused on a Hybrid Projectile (HP), folding-wing UAV design inspired by mortars. This has driven the necessity of a structural analysis of the prototype design to provide vital feedback to designers to ensure that the HP is likely to survive the act of launching. Due to the extreme accelerations during the launching phase, a typical mortar round experiences dramatic impulse loads for an extremely brief duration of time. Such loads are the result of the propellant combustion process. Thermodynamic-based interior ballistic computations have been formulated and were used to solve the dynamic equations of motion that govern the system. Modern ballistic programs solve these equations by modeling the combustion of the propellant. However, mathematical procedures for such analyses require complex models to attain accurate results. Consequently, the objective of this research was to create a ballistic program that could evaluate interior ballistics by using archived pressure-time data without having to simulate the propellant combustion. A program routine created for this purpose reduces the complexity of calculations to be performed and minimizes computational effort, while maintaining a reasonable degree of accuracy for the motion dynamics results (temporal position, velocity, acceleration of the projectile). Additionally, the program routine was used to produce a mathematical model describing the pressure as a function of time, which could be used as loading conditions for more advanced explicit-dynamic finite element simulations to evaluate the transient response and stress wave propagation of the prototype and individual payload components. Such simulations remove uncertainties related to the transient loads needed to assess the structural integrity of the projectile and its components.
A Hybrid Metal-to-Composite Joint Fabricated Through Additive Manufacturing Processes
Authors: Whitney Thomas J. , Gibson Thao , Lafdi Khalid , Welk Brian
Published: October 2013

Devices and machines which perform additive manufacturing (adding material in a layer-wise or bead-wise manner to produce complex structure rather than removing material through machining) are maturing and entering the commercial market. While small prototype parts are routinely made using these devices, a number of industries, including biomedical and aerospace, are considering using these techniques for production parts. New materials which take advantage of the unique capability of additive manufacturing are beginning to evolve. Hybridization of materials at smaller scales now becomes possible with the precision of additive manufacturing devices. However, the fundamentals of structural performance of materials that can be produced by these methods are still to be explored and understood..

The current effort focuses on characterizing and describing the fundamental processing of hybrid materials produced using a combination of laser sintering of metals combined with polymer infusion of advanced carbon fabric. Ultimately, the work seeks to develop a fundamental understanding of the structural mechanics of these novel graphite-metal materials produced through hybrid processes. By understanding development and location of weak structural planes, effects of voids and discontinuities, load transfer from nano to macro scale, reinforcement distribution, gradients in properties, and effects of residual stress, a complete materials design process beginning with structural requirements and ending with material and process selection can be developed.

This paper will summarize the first experimental steps taken to process and fabricate a metal-to-composite hybrid joint using a combination of additive manufacturing and conventional composite processes. Experimental conditions are described and morphology of the resulting hybrids is discussed. Future plans for testing are described.
Shopfoil: Design of Unoptimized Airfoils
Authors: Napolillo Zachary G. , Hamburg Shanti D. , Browning Patrick H. , Huebsch Wade W. , Wilhelm Jay , Gautam Mridul
Published: October 2013

The desire and demand to fly farther and faster has progressively integrated the concept of optimization with airfoil design resulting in increasingly complex numerical tools pursuing efficiency often at diminishing returns, while the costs and difficulty associated with fabrication increases with design complexity. This paper establishes a method utilizing numerical tools for unoptimized design, focused on reducing the complexity of airfoils for applications where aerodynamic performance is less important than the efficiency of manufacturing. We applied this method to the development of a low Re, disposable Hybrid Projectile requiring a 4.5:1 glide ratio, resulting in a series of airfoils which are geometric approximations to highly contoured cross-sections called ShopFoils. This series of airfoils both numerically and experimentally perform within a 10% marigin of the SD6060 at low Re while reducing manufacturing costs and meeting the requirements of the HP platform.
Custom 1-D CFD Numeric Model of Single-Cell Scale Sample Holder for Scanning Thermal Analysis
Authors: Compton Logan M. , Armes James L. , Solbrekken Gary L.
Published: October 2013

Successful cryopreservation protocols have been developed for a limited number of cell types through an extensive amount of experimentation. To optimize current protocols and to develop effective protocols for a larger range of cells and tissues it is imperative that accurate transport models be developed for the cooling process. Such models are dependent on the thermodynamic properties of intracellular and extracellular solutions, including heat capacity, latent heat, and the physical phase change temperatures. Scanning techniques, such as differential-scanning calorimetry (DSC) and differential thermal analysis are effective tools for measuring those thermodynamic properties.

It is essential to understand the behavior of the in house fabricated differential-scanning calorimeter given different cooling and warming rates to reassure and validate the obtained experimental results. A 1-D transient CFD code was created in Matlab using Patankar’s theory to not only validate obtained experimental results but aid in optimizing the control system to produce linear cooling and warming rates. A freezing model was also implemented as a subroutine to numerically observe the effect of heat release and absorption of the sample during a run. The numeric model is composed of a multilayer scheme that incorporates a thermoelectric module which provides the primary temperature control along with the micron sized bridge with sample holder and thermocouple. An electric current profile is imported in from either an experimental run to validate results or from an optimization program to determine the optimum electrical current profile for a desired temperature profile. Numeric detection of heat capacity, latent heat, and thermal resistance has also been demonstrated.
Assessment of Gingival Inflammation Using Ultrasound Imaging
Authors: Sayed Ahmed , Mahmoud Ahmed , Chaves Eros , Crout Richard , Sivaneri Kevin , Mukdadi Osama
Published: October 2013

Gingivitis is the most common gingival inflammation in the oral cavity, and the most prevalent periodontal disease affecting 90% of the population in all age groups. Recently, a few research groups have investigated the possibility of using ultrasound in dentistry, particularly in diagnosing bony destruction in the more severe form of periodontal disease called periodontitis. This work investigates the feasibility of using ultrasound imaging to quantitatively assess gingival tissue inflammation. Signal and image processing of ultrasound data have been performed to quantitatively assess gingival tissue. A number of gingival scans were conducted in vitro to render ultrasound images of high-spatial and contrast resolutions. For each sample the B-mode images were matched with almost the same slices in histology. Results show that ultrasound scans for tissues with gingivitis exhibited low intensity of reflections (hypo echoic) at the inflamed tissues, while healthy dense epithelium layers exhibited higher reflections (hyper echoic). Histological diagnosis revealed good agreement with the ultrasound results indicating the usefulness of such ultrasound imaging in diagnosing gingivitis. In addition, a new design for an intraoral linear array ultrasound probe is demonstrated and utilized in our clinic in vivo. Analysis of the echogenicity patterns of the resultant images demonstrates the potential of using such a new probe in gingival health assessment, which would be feasible and clinical relevant for patient evaluations clinically.
Product Designing, Engineering, Manufacturing of Innovative Products at the Request of Large Retailers
Authors: Seber Brett P.
Published: October 2013

Large Retailers in the USA have evolved in recent years from buying products designed and built by the manufactures, to more of an “import direct” strategy on commodity products. As a result the emphasis for engineering, quality control, and factory support falls back on the Retailer to manage. The downside with such a strategy is the vacuum left for true innovative products.

The Large Retailers find themselves hungry for companies to provide problem solving solutions resulting in patentable innovative products that are outside the norm as provided by most of their vendors.

We developed a successful, proven, R&D and specific Engineering, by designing in manufacturing processes and equipment capabilities as set forth by qualified factories, both domestically and internationally, while working with the Large Retailers to provide patentable innovative products.
Experimental Study of Enhancement and Quenching of Plasmon-Controlled Fluorescence Using Quantum Dot–Plasmonic Nanoparticle Mixtures in Aqueous Medium
Authors: Palombo Nola , Walsh Timothy , Lee Jungchul , Park Keunhan
Published: October 2013

This article reports the enhancement and quenching of quantum dot (QD) emission for different concentrations of plasmonic nanoparticles (PNPs) by utilizing the Brownian motion-induced dynamic near-field interactions in aqueous solution. We measured the fluorescence spectrum of two types of QD-PNP mixtures. The first mixture was QDs (525 nm for emission wavelength) and gold nanoparticles dispersed in distilled water, where the emission wavelength of the QDs matches the localized surface plasmon (LSP) excitation wavelength of the gold nanoparticles. The second mixture was QDs (655 nm for emission wavelength) and silver nanoparticles dispersed in distilled water, where LSPs excited at the wavelength of 392 nm affect the excitation of the QDs. For both experiments, the QD emission spectra were monitored while changing the concentration of the PNPs from 108 to 1011 /mL for a fixed concentration of QDs at 1 × 1013 /mL. For low PNP concentrations, the QD emission was enhanced for 30 nm gold nanoparticles and 80 nm silver nanoparticles; however, for high PNP concentrations, the QD emission was always quenched. This research reveals the dependence of the QD fluorescence on the concentration of PNPs. The obtained results will be beneficial in further understanding plasmonic interactions between QDs and nanoparticles and the manipulation of QD emission, switching from enhancement to quenching or vice versa, with the alteration of nanoparticle concentration.
Precision Micromachining Channels in Highly Elastic Polymers for Applications in Tissue Engineering
Authors: James Thomas P. , Sagar Amrit , Eckman Nathaniel B. , Saigal Anil
Published: October 2013

The aim of this research is to investigate the effect of elastic recovery on the ability to precisely control depth of cut when micromachining channels in poly(methyl methacrylate) (PMMA). Both a standard and impact resistant PMMA were machined using an orthogonal micro-slitting arrangement. While holding speed and cutting edge radius constant, the intended depth of cut was varied from 10 μm to 85 μm in order to determine the actual depth of cut due to chip formation and the fraction of material that was ploughed and then elastically recovered. Elastic recovery was determined by using a profilometer to measure step height after machining a partial groove. Results show that intended depth of cut and actual depth of cut are a function of material properties, with greater ploughing occurring in the PMMA material with lower tensile strength and higher strain to yield. When cutting resulted in a permanent trench being formed, actual depth of cut was related in a linear manner to the intended depth of cut. At lower intended depths of cut, the majority of material was ploughed beneath the cutting edge with little evidence of chip formation. In addition, at lower depths of cut a size effect was observed, where thrust force exceeded cutting force. Greater cutting and thrust forces were evident from the PMMA material with higher tensile strength. Resultant forces for both samples were related in a linear manner to the final trench depth. In general, the results indicate that orthogonal micro-slitting experiments may be used to generate process maps to accurately predict the depth of cut achieved when micromachining channels in highly elastic polymers.
Time Optimal Walking of Human With Below Knee Prosthesis
Authors: Farizeh Tara , Sadigh Mohammad Jafar
Published: October 2013

This paper presents first steps of the solution of time optimal motion of amputees wearing leg prosthesis. To start with, a simplified model is considered. It is assumed that the motion takes place in sagittal plane and the torque limits are independent of joint angles. Moreover the motion is assumed to satisfy zero-moment point stability criterion, nonslip condition and some kinematic constraints of natural walking, in addition to the constraint of internal link wrench limits at the leg prosthesis connection. The problem is formulated as a time-optimal path planning problem with the consideration of equation of motion, stability and non-slip inequality relations, joint torque limits and internal-link wrench limits. The results of this study can shed some light on the problem of walking with prosthesis in order to improve speed and quality of walking of amputees.
A Numerical Simulation of Interfacial Slip and its Role in Friction
Authors: Streator Jeffrey L.
Published: October 2013

The transition from static friction to kinetic friction results from the attainment of a point of instability, whereby interfacial slip becomes more energetically favorable than sticking. Such an instability is explored in this work via a plane-strain elastostatic analysis. A rigid pin of prescribed geometry is placed in contact with an elastic slab and translated horizontally under conditions of constant load. An intrinsic static coefficient of friction is prescribed, which limits the ratio of shear stress to contact pressure at each location within the interface. Additionally, the surface of the elastic slab is given a desired undulation to simulate the effects of surface roughness. As the pin is translated horizontally, a lateral reaction force (i.e., friction force) is developed and is observed to grow nearly linearly with increasing lateral displacement. At a critical point, a substantial portion of the interface experiences slip, leading to a large decrease in the friction force and thereby revealing a stick-slip behavior. It is found that the overall (macroscopic) static friction coefficient can be significantly less than the intrinsic friction coefficient and that the presence of even a small amount of roughness can have a large effect on the friction force.
Designing Multifunctional Polymer Composite for Disaster Monitoring
Authors: Vipulanandan Cumaraswamy , Pakeetharan Srisothinathan
Published: October 2013

In this study, a piezoresistive structural sensor (multifunctional material) was developed and a cantilever beam element with varying cross sections was designed and tested to measure low pressures for use during disaster events such as hurricanes. The piezoresistive structural polymer composite material developed in this study had a compressive strength of over 65 MPa (9425 psi), considered to be stronger than the standard construction materials. Also the piezoresistive material was over 30 times more sensitive than the resistance strain gages in detecting strain. The compressive stress-strain relationship of the polymer composite was modeled using a non-linear relationship. The constitutive behavior of the piezoresistive material was modeled using incremental nonlinear stress-resistivity relationship. The structural response of the cantilever beam with varying cross sections was analyzed using the finite element method. With the newly developed cantilever beam element it was possible to magnify the piezoresistive response and detect applied pressure as small as 1.4 kPa (∼0.2 psi) with a change in electrical resistivity of 0.5%.
Pseudo 3D RVE Based Finite Element Simulation on White Matter
Authors: Pan Yi , Patel Vivak , Pelegri Assimina A. , Shreiber David I.
Published: October 2013

Axonal injury represents a critical target for traumatic brain and spinal cord injuries prevention and treatment. Finite element head models are often used to predict brain injury caused by mechanical loading exerted on the head. Many studies have been attempted to understand injury mechanisms and to define mechanical parameters of axonal injury. Mechanical strain has been identified as the proximal cause of axonal injury. Since the microstructure of the brain white matter is locally oriented, the stress and strain fields are highly axon orientation dependent. The accuracy of the finite element simulations depends not only on correct determination of the material properties but also on precise depiction of the tissues’ microstructure (microscopic level). We applied a finite element method and a mircomechanics approach to simulate the kinematics of axon, which was developed according to experimental data, and found that the degree of coupling between the axons and surrounding cells within the tissue will affect the behavior of the tissue. In this study, the finite element model and the kinematic axonal model are applied to the Representative Volume Element (RVE) of central nervous system (CNS) white matter to investigate the tissue level mechanical behavior. The uniaxial tensile test on the white matter tissue will be presented as an example using the RVE.