bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Functionally Graded Cellular Core on Energy Absorption Response of Thin Walled Composite Axial Members
Authors: Ali Muhammad , Alam Khairul , Ohioma Eboreime
Published: February 2017

Thin walled axial members are typically used in vehicles’ side and front chassis to improve crashworthiness. Extensive work has been done in exploring energy absorbing characteristics of thin walled structural members under axial compressive loading. The present study is a continuation of the work presented earlier on evaluating the effects of presence of functionally graded cellular structures in thin walled members. A functionally graded aluminum cellular core in compact form was placed inside a steel square tube. The crushing behavior was modeled using ABAQUS/Explicit module. The variables affecting the energy absorbing characteristics, for example, deformation or collapsing modes, crushing/ reactive force, plateau stress level, and energy curves, were studied. An approximate 35% increase in the energy absorption capacity of steel tube was observed by adding aluminum graded cellular structure to the square tube. The aluminum graded structure crushed systematically in a layered manner and its presence as core supported the steel square tube side walls in transverse direction and postponed the local (tube) wall collapse. This resulted in composite tube undergoing larger localized folds as compared to highly compact localized folds, which appeared in the steel tube without any graded core. The variation in deformation mode resulted in increased stiffness of the composite structure, and therefore, high energy absorption by the structure. Further, a relatively constant crushing force was observed in the composite tube promoting lower impulse. This aspect has a potential to be exploited to improve the crashworthiness of automobile structures.
STRETCHABLE Lab-on-Chip Device With Impedance Spectroscopy Capability for Mammalian Cell Studies
Authors: Zhang Xudong , Nordin Anis Nurashikin , Li Fang , Voiculescu Ioana
Published: February 2017

This paper presents the fabrication and testing of electric cell-substrate impedance spectroscopy (ECIS) electrodes on a stretchable membrane. This is the first time when ECIS electrodes were fabricated on a stretchable substrate and ECIS measurements on mammalian cells exposed to cyclic strain of 10% were successfully demonstrated. A chemical was used to form strong chemical bond between gold electrodes of ECIS sensor and polymer membrane, which enable the electrodes keep good conductive ability during cyclic stretch. The stretchable membrane integrated with the ECIS sensor can simulate and replicate the dynamic environment of organism and enable the analysis of the cells activity involved in cells attachment and proliferation in vitro. Bovine aortic endothelial cells (BAEC) were used to evaluate the endothelial function influenced by mechanical stimuli in this research because they undergo in vivo cyclic physiologic elongation produced by the blood circulation in the arteries.
Fully Coupled Numerical Simulation for Wave Propagation in Composite Materials
Authors: Li Guoyi , Neerukatti Rajesh Kumar , Chattopadhyay Aditi
Published: February 2017

Composite materials are used in many advanced engineering applications because of their high specific strength and specific stiffness. However, the complex damage mechanisms and failure modes are still not well-understood and limit their wide-spread applications. It is critical to monitor the structural heath for improved understanding of damage evolution and accurate life estimation. Ultrasonic wave based structure health monitoring (SHM) technique is a promising approach and has been investigated by many researchers. However, for the techniques to be reliable, it is necessary to understand the wave propagation behavior in composites. A fully coupled numerical simulation model has been developed to understand wave propagation and dissipation in composites under different excitation frequencies. The model is based on the local interaction simulation approaches/sharp interface model (LISA/SIM), and is computationally efficient compared to traditional finite element methods. This model is used to emulate wave behavior in composites in the current work. The output sensor signals are processed using matching pursuit decomposition algorithm to study the zero-order anti-symmetric and symmetric Lamb wave modes, including attenuation effects and dispersion. The results show good agreement with published experiments. Sensitivity studies show that wave velocities and amplitudes vary significantly with changes in the material properties and stiffness.
Thermo Mechanical Analysis of a Direct Injection Heavy Duty Diesel Engine Piston Using FEA
Authors: Ismail Islam , Emara Ahmed , Abdel Razek El Sayed
Published: February 2017

This paper involves simulation of a 4-stroke direct injection heavy duty diesel engine piston made of aluminum silicon alloy to determine its temperature field, stress distribution and deformation at the conditions of upgrading the engine power from 300 HP to 350 HP. Turbocharger is the way used to enhance the engine power from 300 HP to 350 HP beside improving the fuel injection system. When the engine power is upgraded, high temperature and pressure will be developed because the engine will run at high loads. The piston is subjected to the coupled action of the thermal effect due to the transfer of heat from the head to the body and the mechanical effect represented by the combustion pressure and the inertial load due to the important change of direction of the piston in the cylinder bore. This results in producing stresses in the piston and if these stresses exceed the designed values, the failure of the piston is the result. Finite element analysis (FEA) is considered as one of the best numerical tools to model and analyze the physical systems. The three dimensional piston model was developed in Solid-Works and imported into ANSYS software. Finite element analysis is considered Code for preprocessing, loading and post processing. The simulation parameters used in this paper were combustion pressure, inertial effects and temperature. Diesel RK software is used to simulate the thermal analysis of engine cycle at each case of engine power 300 HP and 350 HP. Also, this model included the effect of the heat flow on the piston to overcome the whole area of the piston is used to illustrate the temperature distribution on the total area of the piston. This area divided into piston surface area and sidle area of piston which included the groves of rings (pressure and oil). The heat transfer coefficient is determined in each area of the piston according to the mechanism of heat transfer. Finally, the results of two different piston conditions are compared with each other. The highest temperature appeared at the combustion chamber side which occurred at the edges of the piston top face in direct contact with the hot gases in the radial. The piston deformation value is within a safe margin and below the gap between the piston and the cylinder bore in case of engine power of 350 HP. The highest calculated value of stresses was below the yield stress of the piston material at elevated temperatures and engine brake power of 350 HP. Hence the piston would withstand the induced stresses during work cycles.
Effects of Various Cooling Techniques on Grain Refinement of Aluminum 7075-T651 During Friction Stir Processing
Authors: Patel Vivek V. , Badheka Vishvesh J. , Zala Samarth R. , Patel Sagar R. , Patel Utsav D. , Patel Swarg N.
Published: February 2017

Aluminum 7075 alloy (AA 7075) is one of the prime materials used in the aviation and automotive industry because of its high strength to weight ratio, good amount of fatigue strength and high machinability. Friction stir processing (FSP) is one of the emerging solid state process that refines the microstructure and hence improved mechanical properties are obtained. The process temperature during FSP affects the resulting microstructure so the attempt for reducing the process temperature can result into reduction in the grain size. The fine grain size microstructure delivers high percentage of elongation which reduces the number of joints and welds in the critical structural applications. So, by implementing coolants such as water and carbon dioxide (CO2) during this process had hindered the grain growth and very fine grained microstructure was obtained. The fine grain microstructure offers higher elongation and hardness as deformation starts from the grain boundaries. In this experimental investigation we intended to keep the temperature generation during the process as low as possible by keeping the process parameters of 765 rpm, 31.5 mm/min fees rate and 20 tilt of the tool (optimized for tapered threaded cylindrical pin tool) constant. All the samples were examined by metallographic characterization using optical microscope. The grain size measurements for all three FSP samples were carried out. Water and CO2 cooled FSP samples reported much more fine grain as compared to naturally cooled sample because of the less heat input during the process.
A Pneumatic Multi-Dome Active Energy Harvesting System
Authors: Goodey Daniel , Fidlar Austin , Denawakage Don Varuna , Hudnell Donnie , Pemberton Ronell , Azzouz Mohamed Salim , Brink Jan
Published: February 2017

When traveling through heavy traffic, vehicles lose a large amount of their kinetic energy. These losses can be attributed to various sources such as the roll friction of the tires against the road pavement. According to the Federal Highway Administration, there are an average of 304,000 cars a day travelling on the US-75 near the Dallas Fort Worth Arlington area in Texas. With so much available energy being wasted, it is essential to find a different way to harness losses so that they can be recycled. The purpose of this research project is to design a system that will harvest some of this lost energy using a set of pneumatic cylinders built into the road. The cylinders will have a dome shape that extends slightly above the surface of the road. As cars pass over this dome the cylinder will retract and compressed air will be sent through a pneumatic system, to an air tank where it is stored. The energy generated by the air stored in the cylinder can be used to drive a pneumatic motor that can turn a generator. The generator could then be used for multiple purposes such as: charge a battery, power a toll booth or other near highway structures. The compressed air stored in the tank may be used for other applications. This is useful due to the fact that almost every industry from the medical industry to the food industry use compressed air to power their pneumatic tools. The pneumatic cylinder will be used in areas of high traffic such as when a car approaches a toll booth, or entrances and exits of multi-level parking garages. The pneumatic cylinder and the associated air flow system using a CAD and a pneumatic software. The behavior of the system could then be tested and be better understood. After the initial simulation testing, a physical prototype has been built in order to gather practical data that can be compared to the simulations. Based on the gathered data on the prototype an assembly of numerous road rumbles can be built and tested on real streets. It is expected that a high pressure will be built in the tank using the prototype. Once pressure is built in the system data will be generated using various instruments, which will show pressure versus time, and pressure versus number of strokes so that the system can be better understood during the testing period. This data will then be used to determine the efficiency, and viability of the proposed system in generating compressed air as a form energy.
Utilizing Reaction Wheels to Increase Maneuverability and Localization Accuracy of a Hovering Robot
Authors: Tatoglu Akin , Greenhalge Sean , Windheuser Kevin
Published: February 2017

Hovercraft like vehicles have various advantages including traveling over almost any non-porous surface. Hovering bodies could use its thrusters to generate an active braking system. However, time required to stop and change direction of the propellers is not sufficient enough for sudden brake needs specifically in obstacle rich co-robot environment. Moreover, high speed sharp turn ability increases path planning algorithms efficiency by reducing overall mission time for any given simple task such as docking to power stations or more sophisticated tasks of sweeping unexplored areas. This paper discusses and examines the application of a reaction wheel mounted to a hovering body to allow for rapid maneuver. Reaction wheel is designed to have enough mass to adjust motion of the hovering robot due to unexpected drift or requested maneuver. Wheel would accelerate to high velocity and experience an instantaneous brake which allows energy stored in moment of inertia to be transferred from wheel to body. Detailed design approach, assembly steps, equations of motion and simulation results incorporated with generated path are discussed. Finally, set of real world experiments were executed and comparison plots are listed. Results showed that solution improves maneuverability of such structure substantially.
On the Influence of External Fields on the Acoustic Characteristics of Phononic Crystals
Authors: Rudykh Stephan , Galich Pavel
Published: February 2017

In this work, we consider elastic wave prorogation in deformable microstructured materials. In particular, we focus on the influence of externally applied deformation on the acoustic characteristic of periodic layered phononic crystals. Based on an analytical solution for the finitely deformed layered media, an analysis of the superimposed on the finitely deformed state small amplitude motions is performed. The analysis provides the information about the important acoustic characteristics such as phase and group velocities, illustrated by the slowness and energy curves. The influence of deformation on these characteristics of phononic crystals is investigated, showing the strong tunability of the phononic crystals by applied deformations.
Minimizing the Acoustic Signature of a Cooling Fan Using the Mesh Morpher Optimizer
Authors: Kheirallah Mike A. , Jawad Badih , Liu Liping
Published: February 2017

Noise reduction is considered as a challenging task in the engineering field. The main objective of this study is focused on providing an optimal new design of a cooling fan with better performance by minimizing the acoustic signature using the surface dipole acoustic power as function. The process of designing a new cooling fan with optimal performance and reduced acoustic signature can be fairly lengthy and expensive. With the use of CFD and specific tools like mesh morphing, in conjunction with state-of-the-art optimization techniques such as Simple model, a given baseline design can be optimized for performance and acoustics. The present study focuses on minimizing the acoustic signature of a given cooling fan using the surface dipole acoustic power as the objective function. The Mesh Morpher Optimizer (MMO) in ANSYS Fluent is used in conjunction with a Simplex model of the broadband acoustic modeling. The broadband model estimated the acoustic power of the surface dipole sources on the surface of the blade without the need for expensive unsteady simulations. It has been shown in the previous work that such a model can provide reliable design guidance. The new promising approach has shown a reduced dipole surface intensity of around 46% of the original value. Other acoustics sources (quadropole noise) are ignored due to the relatively low fan speed considered in this study. Considering this as first attempt study, it is believed that advanced additional studies may improve the model in changing the mesh and objective function.
Heat Transfer in Annular Shear-Thinning Non-Newtonian Flows Over a Sudden Pipe Expansion
Authors: Hammad Khaled J.
Published: February 2017

Non-isothermal suddenly expanding annular pipe flows of a shear-thinning non-Newtonian fluid are numerically studied within the steady laminar flow regime. The power-law constitutive equation is used to model the shear-thinning rheology of interest. A parametric study is performed to reveal the influence of annular-nozzle-diameter-ratio, k, power-law index, n, and Prandtl numbers over the following range of parameters: k = {0, 0.5}; n = {1, 0.6}; and Pr = {1, 10, 100}. Heat transfer enhancement, i.e., wall heat transfer rates higher than the fully developed ones downstream of the expansion plane, is observed only for Pr = 10 and 100. In the case of Pr = 1, wall heat transfer rates monotonically increase to the fully developed value. Higher Pr, k, and n values, in general, result in more significant heat transfer enhancement downstream of the expansion plane. Further, shear-thinning non-Newtonian flows display two local peak wall heat transfer rates, in comparison with only one peak value in the case of Newtonian flows.
Galloping Vibration of Nonlinear Cables Through a Two Degree-of-Freedom Oscillator
Authors: Luo Albert C. J. , Yu Bo
Published: February 2017

In this paper, galloping vibrations of a lightly iced transmission line are investigated through a two-degree-of-freedom (2-DOF) nonlinear oscillator. The 2-DOF nonlinear oscillator is used to describe the transverse and torsional motions of the galloping cables. The analytical solutions of periodic motions of galloping cables are presented through generalized harmonic balanced method. The analytical solutions of periodic motions for the galloping cable are compared with the numerical solutions, and the corresponding stability and bifurcation of periodic motions are analyzed by the eigenvalues analysis. To demonstrate the accuracy of the analytical solutions of periodic motions, the harmonic amplitudes are presented. This investigation will help one better understand galloping mechanism of iced transmission lines.
Design, Fabrication, and Characterization of a Soft Multi-Fingered Hand
Authors: Johnson Lena , Bruck Hugh A. , Gupta Satyandra K.
Published: February 2017

This paper describes the design, fabrication, testing and modeling of the SUR Hand. The SUR Hand is a soft, under actuated robotic hand. Through an iterative design and manufacturing process, SUR Hand’s soft, actuating components have been adapted from the original PneuFlex, pneumatically actuated finger to be highly flexible and capable of actuating a precision force. This paper shows how altering the design parameters of the fingers altered their overall performance. Furthermore, it details the experimental setup for testing the components, as well as the modeling methods used. Finally, it shows the process for creating and validating a geometric model that characterizes proper grasping strategies, assuming a passive palm component.
Lift and Drag Forces of a High Efficiency Airfoil With an Embedded Rotating Cylinder
Authors: Gada Komal , Rahai Hamid
Published: February 2017

Numerical investigations of an optimized thin airfoil with an active flow control device (rotating cylinder) embedded into the airfoil have been performed. The objective of the study was to investigate the possibility of using a rotating cylinder to maintain performance of micro aerial vehicles, MAVs, when significant and sudden variation in wind speed (example: gust) is present. The airfoil has a chord length of 19.66 cm and a span of 25 cm. The free stream mean velocity was 20 m/s which corresponds to a chord length Reynolds number of 2.54×105. Simulations were performed at 17 degrees angle of attack which include the initial angle that the cambered leading edge makes with the incoming axial flow. Simulation results for the airfoil without the embedded cylinder have shown flow separation at approximately 85% chord length. Then, a rotating cylinder with a 0.51 cm diameter was embedded into the airfoil, spanning the width of the airfoil at slightly downstream of the location of flow separation, i.e. at x/c = 0.848. There was 1 mm spacing between the cylinder and the airfoil, to allow cylinder’s rotation. Investigations were performed at different rotation speeds, corresponding to corresponding tangential velocities being higher than, equal to and less than the local axial freestream mean velocity. Results showed approximately 10% improvement in lift to drag ratio (L/D), when the tangential velocity was the same or higher than the local axial mean velocity.
Mechanical Behavior and Microstructure of Electron Beam Melted Ti-6Al-4V Using Digital Image Correlation
Authors: Haque Mohammad Shafinul , Arrieta Edel , Mireles Jorge , Carrasco Cesar , Stewart Calvin M. , Wicker Ryan B.
Published: February 2017

The reputation of additive manufacturing technology has increased dramatically in recent years due to its freedom of design, customization, and waste minimization. The growing demand for complex profile components to achieve more economic and strength-to-weight efficient aero-engine components can be met by additive manufacturing technology. In this study, electron beam melting (EBM), a powder bed additive layer manufacturing process, is used to manufacture Ti-6Al-4V tensile specimens. The Ti-6AL-4V alloy has excellent corrosion and high temperature resistance with a high strength-to-weight ratio. It is widely used in the power generation, aerospace, and medical industries. An Arcam Ti-6Al-4V prealloyed powder with particle sizes ranging from 45μ–100μ is used in an Arcam A2 machine to manufacture three specimens at zero degree manufacturing orientation. The zero degree manufacturing orientation is expected to exhibit a higher strength over other orientations. The EBM manufacturing parameters were set at 15mA current and 4530 mm/sec beam speed. Tensile tests were performed at room temperature (25.5°C) under a strain rate of 0.003 mm/mm/min according to the ASTM E8 standard for strain-rate sensitive materials. Stress-strain curves are plotted and discussed. Tensile test results indicate a tensile strength of 1.2 GPa and an elongation of 8% approximately. Three Dimensional Digital Image Correlation (3D-DIC) is used to measure the full strain field and deformation evolution on the surface of the specimens. The 3D-DIC system compares digital photographs (taken at two different angles simultaneously) of the surface of a specimen and calculates the deformation and strain fields. Using the strain fields the mechanical properties are determined by the relationships in the strain tensor. The tensile test results show that for a zero degree manufacturing orientation, the yield strength (YS) and ultimate tensile strength (UTS) are higher than that typically reported for wrought products. Fractography using optical microscopy (OM) and Scanning Electron Microscopy (SEM) were conducted. Micrographs of transverse section of the specimen were obtained to identify and analyze the failure mechanism that took place during testing. The built direction, presence of voids, manufacturing defects, and unmelted particles are observed from the SEM views. Surface roughness and microstructure were observed in the OM. A comparison of the obtained results with the literature for additively manufactured Ti-6Al-4V and possible causes are discussed.
Numerical Investigation on Viscous Dissipation Effect in Forced Convection in Rectangular Microchannels With Nanofluids
Authors: Buonomo Bernardo , Cirillo Luca , Ercole Davide , Manca Oronzio , Nardini Sergio
Published: February 2017

In this paper a numerical investigation on laminar forced convection flow of a water-Al2O3 nanofluid in a rectangular microchannel, taking into account the viscous dissipation, is accomplished. A constant and uniform heat flux on the external surfaces has been applied and a single-phase model approach has been employed. The analysis has been performed in steady state regime for particle size in nanofluids equal to 38 nm. The CFD commercial code Ansys-Fluent has been employed in order to solve the 3-D numerical model. The geometrical configuration under consideration consists in a duct with a rectangular shaped crossing area. A steady laminar incompressible flow with viscous dissipation and different nanoparticle volume fractions has been considered. The base fluid is water and nanoparticles are made up of alumina (Al2O3). Thermo-physical properties of the nanofluid are considered constant with temperature. The length the edge and height of the duct are 0.030 m, 1.7 × 10−7 and 1.1 × 10−7 m, respectively. A constant and uniform heat flux q on the top wall is applied, the others are adiabatic and at the inlet section uniform temperature and velocity profiles are assumed. The results showed the increase of the convective heat transfer coefficients, in particular, for high concentration of nanoparticles and for increasing values of Reynolds number. However, the disadvantages are represented by the growth of the wall shear stress and the required pumping power, observed in particular, at high particle concentrations.
On Dynamic Modelling of Compressed Air Engine With Connecting-Rod-Crank to Control Angular Position of Oscillating Rotation
Authors: Alves Alexandre C. , Balthazar Jose M. , Tusset Angelo M. , Rocha Rodrigo T. , Bueno Atila M.
Published: February 2017

In this work is examined the dynamic behavior and the controllability of a compressed air engine with a connecting-rod-crank. The pneumatic motor is composed by a monocylinder, a connecting-rod and a control crank to the oscillating rotation. For the obtainment the nonlinear mathematical model was considered the Lagrange’s method and the components of the physical system in the model are considered as rigid bodies with unilateral restriction. Numerical analysis of the application of the passive control position by a nonconservative pneumatic force with pilot valves in the cylinder showed that it was not possible an exact control to the angular position desired for the output crank. To solve this problem, it is proposed an active control by the Linear Quadratic Regulator method (LQR), to the control of the connecting-rod-crank mechanism. In addition, the robustness of the proposed control technique is tested considering noise measurement in pneumatic external excitation. The numerical simulation results showed the efficiency of the proposed control to the nonlinear dynamic model of the connecting-rod-crank and the sensibility analysis for parametric errors to the control of the oscillating angular positions, demonstrating so that the proposed active control is adequate for this system.
Design and Prototype of a Two-Axis Acoustic Levitator
Authors: Clough Justin , Sracic Michael W. , Piombino Daniel , Braaten Jonathan , Connors Scott , Pedigo Nathaniel , Prantil Vincent , Suthar Kamlesh
Published: February 2017

The purpose of this paper is to document the process required to design and prototype a two-axis acoustic levitator and to show that the two-axis levitator improves the stability of a particle in an acoustic levitation field. The levitator design consists of the following subsystems: the transducer assemblies, which are responsible for generating the acoustic pressure field needed for levitation; the electrical system, which is responsible for providing the transducer assemblies with adequate power to maintain levitation; and the frame structure, which is responsible for locating and rigidly supporting the transducer assemblies.

The two-axis levitator is designed to have four transducers that operate at 27.2 kHz, and simulated results show that the system satisfies nearly all the design criteria and objectives. A transducer test stand and prototype were constructed to verify the design. The test stand was used to characterize all four transducers, and once the assembly was constructed the prototype operating frequency was determined to be 27.5 kHz. The prototype was used to successfully levitate Styrofoam pellets, a plastic pellet, and water droplets of various sizes. The displacement of a water droplet of approximately 1 mm in diameter was measured when levitated with both one-axis (vertical) and two-axis (vertical and horizontal) levitation. Using one-axis levitation, the water droplet displaced a maximum of 1.1 mm in the horizontal direction and 0.17 mm in the vertical direction. Using two-axis levitation, the horizontal displacement was 0.07 mm and the vertical displacement was 0.05 mm. Therefore, the two-axis acoustic levitator provides significant improvements in levitated particle stability.
On Time-Delay Effects on Period-1 Motions in a Periodically Forced, Time-Delayed, Duffing Oscillator
Authors: Luo Albert C. J. , Xing Siyuan
Published: February 2017

In recent decades, nonlinear time-delay systems were often applied in controlling nonlinear systems, and the stability of such time-delay systems was very actively discussed. Recently, one was very interested in periodic motions in nonlinear time-delay systems. Especially, the semi-analytical solutions of periodic motions in time-delay systems are of great interest. From the semi-analytical solutions, the nonlinearity and complexity of periodic motions in the time-delay systems can be discussed. In this paper, time-delay effects on periodic motions of a periodically forced, damped, hardening, Duffing oscillator are analytically discussed through a semi-analytical method. The semi-analytical method is based on discretization of the differential equation of such a Duffing oscillator to obtain the corresponding implicit discrete mappings. Through such implicit mappings and mapping structures of periodic motions, period-1 motions varying with time-delay are discussed, and the corresponding stability and bifurcation analysis of periodic motions are carried out through eigenvalue analysis. Numerical results of periodic motions are illustrated to verify analytical predictions. The corresponding harmonic amplitude spectrums and harmonic phases are presented for a better understanding of periodic motions in such a nonlinear oscillator.
Analysis of Two-Dimensional Heat Diffusion Using FEA and the Fundamental Collocation Method
Authors: Khalilollahi Amir , Mahajerin Enayat , Burgess Gary
Published: February 2017

Finite Element Analysis (FEA) and the Laplace Transform-Based Fundamental Collocation Method (FCM) are used to solve the heat diffusion equation in two-dimensional regions having arbitrary shapes and subjected to arbitrary initial and mixed type boundary conditions. In the FEA method, the time derivative is replaced with a finite difference approximation. The resulting time dependent global equations are solved incrementally starting with the initial conditions. The FCM approach is applied in the Laplace transform domain to obtain temperatures in the s-domain, T(x,y,s). An inversion technique is used to retrieve the time domain solution, T(x,y,t). To compare applicability and accuracy of these methods, both techniques are applied to transient heat flow problems for which exact solutions are known.
Multiple Sclerosis Symptom Analyzer
Authors: Guerrera Brittany , Farrow Samantha , Zeng Gloria , Shady Sally F.
Published: February 2017

Multiple Sclerosis (MS) is a chronic neurodegenerative disease of the central nervous system. MS is typically diagnosed between the ages of 20 and 40. There is no known cause of the disease and each individual experiences varying signs and symptoms depending on the severity of their disease. The most common symptoms include tremor, debilitated gait, visual impairment, or cognitive and emotional disturbances.

Current methods used to treat MS include oral medication and surgical treatment. The issues with oral medication are the unwanted side effects to otherwise healthy tissue and the lack of patient adherence. Surgical treatment can be invasive and require longer recovery times. An alternate strategy to treat MS is by increasing the knowledge base of the practitioner to potentially treat specific symptoms. Currently, physicians use observations and MRI scans of the brain and spinal cord to help diagnose and track the progression of MS. There are several studies that analyze existing assistive technology to aid in the treatment of MS tremors. Most of these studies did not involve large test groups, therefore it is difficult to prove their validity. Additionally, none of the current devices are able to track symptoms while simultaneously creating medical history records.

The goal of the design is to create a new device that will obtain the frequency and amplitude of tremors, while analyzing the effects of temperature and heart rate on the intensity of the tremor. With this data, the device will advance further MS research and lead to better diagnosis and treatment.
On Periodic Motions in the First-Order Nonlinear Systems
Authors: Luo Albert C. J. , Xu Yeyin , Chen Zhaobo
Published: February 2017

In this paper, analytical solutions of periodic motions in the first-order nonlinear dynamical system are discussed from the finite Fourier series expression. The first-order nonlinear dynamical system is transformed to the dynamical system of coefficients in the Fourier series. From investigation of such dynamical system of coefficients, the analytical solutions of periodic motions are obtained, and the corresponding stability and bifurcation of periodic motions will be determined. In fact, this method provides a frequency-response analysis of periodic motions in nonlinear dynamical systems, which is alike the Laplace transformation of periodic motions for nonlinear dynamical systems. The harmonic frequency-amplitude curves are obtained for different-order harmonic terms in the Fourier series. Through such frequency-amplitude curves, the nonlinear characteristics of periodic motions in the first-order nonlinear system can be determined. From analytical solutions, the initial conditions are obtained for numerical simulations. From such initial conditions, numerical simulations are completed in comparison of the analytical solutions of periodic motions.
Voltage Response of Primary Resonance of Coaxial Vibrations of Electrostatically Actuated DWCNT
Authors: Caruntu Dumitru I. , Juarez Ezequiel
Published: February 2017

This work investigates the voltage response of electrostatically actuated of Double-Wall-Carbon-Nano-Tube (DWCNT) parallel to a ground plate (electrode). The voltage between the DWCNT and the ground plate is an Alternating Current (AC) voltage whose frequency is near half of the fundamental natural frequency of the DWCNT. Since the application of this research is mass sensing, and the low power consumption is desired, the Direct Current (DC) voltage is not included in this work. DWCNT coaxial vibrations are investigated. Numerical solutions of this problem are reported.
Self-Assembly of Protruding Islands on Spherical Substrates by Surface Instability
Authors: Liao Xiangbiao , Chen Xi
Published: February 2017

Through strain-induced morphological instability, protruding patterns of roughly commensurate nanostructures are self-assembled on the surface of spherical core/shell systems. A three-dimensional (3D) phase field model is established for closed substrate. We investigate both numerically and analytically the kinetics of the morphological evolution, from grooves to separated islands, which is sensitive to substrate curvature, misfit strain and modulus ratio between core and shell. The faster growth rate of surface undulation is associated with the core/shell system of harder substrate, larger radius or misfit strain. Based on a Ag core/SiO2 shell system, the self-assemblies of protruding SiO2 nano-islands are explored experimentally. The numerical and experimental studies herein could guide the fabrication of ordered quantum structures via surface instability on closed and curved substrates.
Optimal Thermal Design of Fin-and-Tube Heat Exchangers by Integration of a SUMT and a SCGM
Authors: Li Xinyi , Ma Ting , Wang Qiuwang
Published: February 2017

It is a recognized hard task for the traditional thermal design of compact heat exchangers to obtain the optimal geometric parameters efficiently and effectively, owing to its complex trial-and-error process. In response to this issue, a simplified conjugate-gradient method (SCGM) combined with a sequential unconstrained minimization technique (SUMT) as a favorable optimization technique is incorporated with the traditional thermal design in this study, and then the key geometric parameters of fin-and-tube heat exchangers (FTHEs) are investigated and optimized successfully. In this method, the minimum total weight of FTHEs as the final objective is discussed, involving two geometric parameters, diameter of tube and height of shape as search variables. Aiming to minimize the objective function, SCGM is introduced to the SUMT to update the search variables continually with the fixed search steps and the search directions. Meanwhile, with the known geometric parameters from the SUMT, the log-mean temperature difference method (LMTD) is applied to determine the heat transfer area under the combined structure sizes for a given heat duty. Additionally, optimization results for three different heat duty is discussed in this work. The results show that it is effective to obtain the optimal sets of geometric parameters of FTHEs by the present method, and there are some guidance values for the thermal designs of compact heat exchangers.
The Contact Dynamic Modeling and Analysis Based on Spline Assembly Feature Information
Authors: Wang Yu , Yao Shouwen , Yan Qingdong , Liu Jilin , Zhang Qinghua
Published: February 2017

Generally, there is clearance between internal and external spline for the convenience of assembly. Because of the error caused by the process of production and assembly, the clearance is not consistent. This causes nonuniformity of load distribution among spline teeth, which reduce the service life of spline and influence the quality of transmission. In order to analyze these phenomenon, a contact dynamic model based on spline assembly feature is presented. Here, an information model called spline assembly feature, which contains the information of dimension, tolerance and material, is established. Based on Dimensional and Geometrical Product Specification and Verification (GPS), the deviation of minor diameter face and tooth flank is calculated, and the specification surface model is generated based on Small Displacement Theory (SDT). The contact situation of spline engagement is analyzed. With the use of collision algorithm, actual contact state is simulated and the penetration depth of contact zone is obtained. Material mechanics analysis is performed to acquire the rigidity of teeth meshing. With the work above, a multi-rigid dynamic model of spline is established based on continuous contact force theory and Hertz contact theory. Two indexes are introduced to evaluate the nonuniformity of load on spline teeth under stable condition and impact condition. Results show that the model is more accurately to predict dynamic performance.
A Leader-Following Formation Control of a Group of Mixed-Type Mobile Robots
Authors: Lee Ho-Hoon , Koutsougeras Cris
Published: February 2017

This paper proposes a leader-following formation control for a group of mixed-type mobile robots such as unicycle-type, carlike, and forklift-type robots. These robots are quite different in kinematics and dynamics. The leader follows its desired trajectory while the rest of robots are following the leader in a specified formation. The proposed formation control computes the desired driving force and steering torque of each robot. The proposed control consists of a formation control scheme and a kinematic trajectory generation scheme for the leader of a group. The nonholonomic constraints of each of the mixed-type mobile robots are taken into account in the design of the formation control and trajectory generation schemes, in which the Lyapunov stability theorem and the loop shaping method are used as design tools. Under certain conditions, the proposed formation control guarantees asymptotic stability while keeping all internal signals bounded. The effectiveness of the proposed control has been shown with realistic computer simulations.
Position Control of a Manipulator Robotic Arm Considering Flexible Joints Driven by a DC Motor and a Controlled Torque by a MR-Brake
Authors: Lima Jeferson J. , Rocha Rodrigo T. , Janzen Frederic C. , Tusset Angelo M. , Bassinello Dailhane G. , Balthazar Jose M.
Published: February 2017

This paper presents a two-degree-of-freedom robotic arm design with flexible joints driven by a DC Motor and controlled by a Magnetorheological (MR) Brake, considering a feedback control. The MR Brake is used to provide adjustable constraints in motion of the manipulator and compensate overshoot by interactions between the robot’s links and flexible joints of the motor drive mechanism. The torque of the MR Brake is obtained by the Radial Basis Function Neural Networks (RBFNN), which is a widely used class of neural networks for prediction or approximation of function. The RBFNN provides the nonlinear curve of hysteresis of MR brake to use torque. Two controllers were proposed to control the manipulator. The first one is obtained by feedback linearization control with the objective to remove the non-dependent terms of the state space equation. The second one is the feedback control obtained using the State-Dependent Riccati Equation (SDRE) with the objective of controlling the position of the manipulator and the torque applied on the MR brake. The numerical simulation results showed that the proposed control using both signal feedback linearization control and a feedback control signal by a DC Motor and MR Brake is effective to control the flexible joint manipulators.
Effect of Groove Dimension on Thermal Performance of Turbulent Fluid Flow in Internally Grooved Tube
Authors: Pirbastami Sogol , Moujaes Samir
Published: February 2017

A Computational Fluid Dynamics (CFD) study of heat enhancement in helically grooved tubes was carried out by using a 3-dimensional simulation with the STARCCM+ simulation package software. The k-ε model selected for turbulent flow simulation and the governing equations were solved by using the finite volume method. Geometric models of the current study include 3 rectangular grooved tubes with different groove width (w) and depth (e) which varies from 0.2 mm to 0.6 mm for the same tube length of 2.0m and diameter of 7.1 mm. The simulations were performed in the Reynolds number (Re) range of 4000–10000 with a uniform wall heat flux of 3150 w/m2 applied as a boundary condition on the surface of each tube. The purpose of this research is to investigate the effect of different groove dimensions on the thermal performance and pressure drop of water inside the grooved tubes and clarify the structural nature of the flow in regards to flow swirl and turbulent kinetic energy distributions. It was found that the highest performance belongs to the groove with these dimensions (w = 0.2 mm and e = 0.2 mm) which was considered for further study. Then, for these same groove dimensions four pitch size to tube diameter (p/D) ratios ranging from 1 to 18 were simulated for the same 2.0 m length tube. The results for Nusselt number (Nu) and friction factor (f) showed that by increasing the (p/D) ratio both the Nu numbers and the friction factors (f) values decrease. With a smaller pitch length (p) the turbulence intensity generated by the internal groove was also found to increase. The physical behavior of the turbulent flow and heat transfer characteristics were observed by contour plots which showed an increasing swirl flow and turbulent kinetic energy as p/D decreases. With an increase of the Nu number for smaller p/D ratio, a penalty of a higher pressure drop was obtained. The results were validated with a previous experimental work and the average error between the experimental and CFD Nu numbers and f were 13% and 8% respectively. A higher level of turbulent kinetic energy is observed near the grooves, as compared to the smooth areas of the pipe surface away from the grooves, which are expected to lead to higher levels of heat transfer. The effect of pitch length (p) on the flow pattern were plotted by streamlines along the tubes, by decreasing the pitch size (p/D ratio) an increase in the swirl is noticed as evidenced by the plots of the path lines. Finally, empirical correlations for Nusselt number and friction factor were provided as a function of p/D and Re number. This study indicates that the incorporation of the internal groove, of particular dimensions, can lead to an improvement of performance in heat exchanger devices. A limited variation of the groove dimensions was conducted and it was found that the values of Nu and f do not improve with an increase of (w) nor with that of (e) from 0.2–0.6 mm.
Design and Development of a Folding Electrically Assisted Bicycle
Authors: El-Sayed Mohamed , Lingerfelt David , McGuire Austin , Wicker Allan
Published: February 2017

With the rapid development of hybrid and electrically driven transportation systems, several concepts of electrically driven bicycles have been developed and introduced to the market. Also, for storage advantage and portability several versions of folding bikes are available in the market.

In this paper, the design, development and validation process for creating a version of a folding electrically assisted bicycle is presented. The designed, developed, and road tested bicycle concept is targeted for use by college students, exercise enthusiast, or for commuting to work. It is also intended as a means of transportation for those living in large cities with a considerable riding distance and a limited space to store a bicycle. In addition to being foldable, the electrically assisted bicycle is designed with a small footprint and a ride performance comparable to any normal city bicycle.

To achieve the design objectives, the process starts with identifying the key attributes such as portability, durability, drivability, maintainability, and safety. The steps for translating the targeted attributes to design criteria and product specifications are discussed. Consequently, the analysis and integration technical tasks needed to achieve the established bicycle specifications for both architectural and performance integration efforts are identified.

During the early stages of the design phase, different alternatives and off-the-shelf components are considered. Architectural and performance integration activities including detailed virtual modeling, simulations, and analyses are implemented to develop the bicycle and achieve targeted attributes within the design constraints.

For concept proofing, the designed concept was developed and road tested. Preliminary results of physical testing demonstrate the achievement levels of different targeted attributes. While some targets were achieved, the initial physical tests indicate that further design improvements are needed through additional development and validation iterations. These improvements could be achieved through adjustment of targets, weight reduction, and alternative materials.