bluuebunny/crossref_metadata_2025 huggingface dataset:
Integration of Geometry and Analysis for the Study of Liquid Sloshing in Vehicle System Dynamics
Authors: Nicolsen Brynne , Shi Huailong , Wang Liang , Shabana Ahmed A.
Published: January 2018

Commonly-used sloshing models are either unable to capture changes in the continuous distribution of the fluid free surface, or are not suited for the integration with high fidelity computational multibody system (MBS) algorithms. The objective of this investigation is to address this deficiency by developing a new continuum-based liquid sloshing approach that accounts for the effect of complex fluid and tank geometry and can be systematically integrated with MBS algorithms in order to allow for studying complex motion scenarios. A unified geometry/analysis mesh is used from the outset to examine the effect of liquid sloshing on railroad and highway vehicle dynamics during various maneuvers including braking and curve negotiation [1,2]. Using a non-modal approach, the geometry of the tank and fluid is accurately defined, a continuum-based fluid constitutive model is developed, and a fluid-tank contact algorithm using the penalty approach is employed. In order to examine the effect of liquid sloshing on vehicle dynamics during curve negotiation, a general and precise definition of the outward inertia force is defined, which for flexible bodies does not take the simple form used in rigid body dynamics. During maneuvers, the liquid may experience large displacements and significant changes in shape that can be captured effectively using absolute nodal coordinate formulation (ANCF) finite elements. For rail systems, the liquid sloshing model is integrated with a three-dimensional MBS vehicle algorithm, in which the three-dimensional wheel/rail contact force formulation is used to account for the longitudinal, lateral, and spin creep forces that influence vehicle stability. The effects of fluid sloshing on vehicle dynamics in the case of a tank partially filled with liquid are studied and compared with the equivalent rigid body model in braking and curve negotiation. The results obtained in the study of the rail vehicle model show that liquid sloshing can exacerbate the unbalance effects when the rail vehicle negotiates a curve at a velocity higher than the balance speed, and can significantly increase coupler forces during braking. Analysis of the highway vehicle model shows that the liquid sloshing changes the contact forces between the tires and the ground — increasing the forces on certain wheels and decreasing the forces on other wheels — which in cases of extreme sloshing, can negatively impact the vehicle stability by increasing the possibility of wheel lift and vehicle rollover.
Modeling the Influence of Build Orientation on the Monotonic and Cyclic Response of Additively Manufactured Stainless Steel GP1/17-4PH
Authors: Siddiqui Sanna F. , O’Nora Nathan , Fasoro Abiodun A. , Gordon Ali P.
Published: January 2018

Rapid prototyping has led to strides in improved mechanical part design flexibility and manufacturing time. Along with these advances, however, is the extremely high costs associated with additively manufacturing components that can limit a comprehensive understanding of the mechanical performance of these materials. This can be circumvented through the use of constitutive models which can both support experimental findings in addition to providing approximations of expected material behavior. The present study has demonstrated the influence of build orientation on as-built direct metal laser sintered (DMLS) stainless steel (SS) GP1/17-4PH, manufactured along varying orientations in the xy build plane, through strain-controlled tension and completely reversed low cycle fatigue experiments. Experimental findings from monotonic tension testing are used to model failure surfaces, which can be used to approximate failure regions for DMLS SS GP1 manufactured along varying build orientations within the horizontal xy build plane. Further, a Chaboche model is used to simulate the cyclic response of this material based upon experimental findings through low cycle fatigue testing. Conclusive findings from these models are used to assess the vital role that build orientation plays in affecting the mechanical performance of additively manufactured materials.
Sound Source Separation Using Spectrogram Analysis by Neural Networks
Authors: Doura Tomoki , Shiraishi Toshihiko
Published: January 2018

The performance of neural networks has been dramatically improved since the method called “deep leaning” was developed around 2006[1][2]. Mainly, neural networks have been used for classification problems such as visual pattern recognition and speech recognition. However, there are not so many studies of sound source separation using neural networks. To apply neural networks to separation problems, separation problems require to be transformed into classification problems. To realize it, we referred to spectrogram analysis by specialists. Specialists can separate each source signal from the spectrogram of mixed signals by focusing on each local area of the spectrogram. In this study, we developed a novel method for sound source separation using spectrogram analysis by neural networks. As a result of the simulation, we successfully separated male and female voices from their mixed sound. The proposed method is superior to conventional methods in separation problems with sound reflection on walls and convolutional mixture which includes the difference of traveling time from a sound source to microphones because the method does not require to identify the mixture process in space.
Thermal Analysis of Electron Beam Additive Manufacturing Using Ti-6Al-4V Powder-Bed
Authors: Rahman M. Shafiqur , Schilling Paul J. , Herrington Paul D. , Chakravarty Uttam K.
Published: January 2018

Electron Beam Additive Manufacturing (EBAM) is one of the emerging additive manufacturing (AM) technologies that is uniquely capable of making full density metallic components using layer-by-layer fabrication method. To build each layer, the process includes powder spreading, pre-heating, melting, and solidification. The thermal and material properties involved in the EBAM process play a vital role to determine the part quality, reliability, and energy efficiency. Therefore, characterizing the properties and understanding the correlations among the process parameters are incumbent to evaluate the performance of the EBAM process. In this study, a three dimensional computational fluid dynamics (CFD) model with Ti-6Al-4V powder has been developed incorporating the temperature-dependent thermal properties and a moving conical volumetric heat source with Gaussian distribution to conduct the simulations of the EBAM process. The melt-pool dynamics and its thermal behavior have been investigated numerically using a CFD solver and results for temperature profile, cooling rate, variation in density, thermal conductivity, specific heat capacity, and enthalpy have been obtained for a particular set of electron beam specifications.
Evaluation of 7050 Aluminum Plates Joined by Friction Stir Welding Using Acoustoelastic
Authors: García Ruano Shirley Alexandra , Bertelli Felipe , Antunes dos Santos Auteliano
Published: January 2018

The 7050-T7451 aluminum alloy has been widely used in the aerospace industry. Due to its chemical composition, this alloy has high levels of mechanical properties that allow the production of low-weight aircraft structural components. However, these alloys are thermally treatable and are not able to bear manufacturing processes involving heat. Because of the importance of their applications, studies based on the development of solid state welding process would be desirable aiming to find an alternative to generate welded joints for this kind of components. In this work, an investigation concerning the behavior of the 7050-T7451 aluminum alloy during Friction Stir Welding (FSW) was carried out. The profile of longitudinal residual stresses of plates welded by the FSW process was obtained using the ultrasonic method through critically refracted longitudinal waves (LCR). Two different frequencies were employed, 3.5 MHz and 5 MHz. The measurements were performed in the longitudinal direction of the welded joint at different distances from the center line of the weld. The magnitude and distribution of residual stresses found with this method are consistent with literature review, reaching 150MPa on the center of the weld.
Numerical Simulation of Mixed Compression Intake Buzz
Authors: Soltani M. R. , Abedi M. , Askari R.
Published: January 2018

Numerical analysis has been conducted to simulate and capture Buzz phenomenon in a supersonic mixed compression air intake. Buzz is an unsteady self-sustained phenomenon occurred in supersonic intakes, especially when operating its subcritical condition, during which the system of compression and shock waves oscillate and move upstream and downstream along the intake. An axisymmetric and unsteady numerical simulation was used to solve Navier-Stokes equations in combination with URANS SST k-ω turbulence model The simulations were performed at M = 2.0 and at a specific subcritical point of the intake operation where buzz was detected experimentally. Results are compared with experimental pressure data. Buzz is captured numerically, and the results show that the buzz oscillation in this intake is periodic, during which the intake duct is loaded and unloaded. The results show that the large separation region on the compression ramp blocks the duct entry and causes the conical and lambda shocks located on the compression ramp to move upstream cause the self-sustained oscillation. The calculated buzz frequency is in agreement with the experimental one, and the difference is less than 0.2%. Further, the peak and trough of both total and static pressure fluctuations, and as a result, the amplitude of buzz are all accurately predicted.
3D Effects in the Wake Vortex Formation of an Elliptic Flat Plate in Hover
Authors: Nair Vivek , Chintamani Siddarth , Dennis B. H.
Published: January 2018

A Numerical Analysis is conducted to investigate the Leading Edge Vortex (LEV) dynamics of an elliptic flat plate undergoing 2 dimensional symmetric flapping motion in hover. The plate is modeled with an aspect ratio of 3 and a flapping trajectory resulting in Reynolds number 225 is studied. The leading edge vortex stability is analyzed as a function of the non dimensional formation number and a vorticity transport analysis is carried to understand the flux budgets present. The LEV formation number is found to be 2.6. The results of vorticity analysis show the highly three dimensional nature of the LEV growth for an elliptic geometry.
Structural Acoustic Physics Based Modeling of Curved Composite Shells
Authors: Hesse Rachel E. , Hulton Andrew W.
Published: January 2018

Understanding sound wave propagation through a curved shell geometry is essential for a wide variety of underwater applications. The objective of this study was to use physics-based modeling (PBM) to investigate wave propagations through curved shells that are subjected to acoustic excitation. An improved understanding of the absorption and reflection properties of materials, such as fiber-reinforced polymer (FRP) composites, will enhance the design methods for a variety of Navy products such as acoustic sensors, acoustic windows, and unmanned underwater vehicles.

The research documented in this report investigates the reflection and transmission coefficients of both flat plates and curved shells for steel and composite materials. Results show that the finite element computational models accurately match analytical calculations, and that the composite material studied in this report has more desirable reflection and absorption properties than steel for typical Navy applications. This research also explores the use of coupled Eulerian-Lagrangian (CEL) and smoothed particle hydrodynamics (SPH) modeling approaches in place of the current, traditional Lagrangian approach. Unfortunately, these approaches were found to be unsuitable for the type of acoustic analyses performed throughout this research. However, results from the traditional Lagrangian approach confirmed the validity of current modeling techniques and allowed for the study of the acoustic properties of various geometries and materials. This can help drive future research on composite material applications and enhance design methods for future Navy products.
Development of an Automatic Thermal, Electrical, and Mechanical Test Platform for Polymer-Derived Ceramics
Authors: Li Ni , Shen He , Lin Jason , Tang Catherine , Ghobrial Antony , Kwong Melanie , Mendoza Joceyln
Published: January 2018

Polymer-derived ceramics (PDC), prepared through thermal decomposition of polymeric precursors, are piezo-resistive, high-temperature resistant, and corrosion resistant material. Due to their excellent thermomechanical and electromechanical (piezo-resistive) behavior with very large gauge factors, they have great potential in being used as sensing materials in harsh environment, and thus has received extensive attentions in recent years. A better understanding of their holistic thermomechanical and electromechanical properties is crucial to the improvement of both the material and corresponding sensor designs. However, there has been a lack of customized, low-cost, and automatic machine that allows researchers to study the complex properties of PDCs. In this paper, an automated platform is designed to study the electromechanical and thermomechanical properties of newly developed PDCs. Featured with automatic temperature control and pressure control capabilities, the platform is able to apply load smoothly from 0 N to 220 N, and add heat from 0 to 250°C.
A Study of Weight-Based Compensation for Asymmetric Upper Limb Growth Secondary to Pre-Pubertal Operative Humeral Epiphyseal Plate Damage
Authors: Fernandez Ryan , Fernandez Tricia , Fernandez Dane , Jawad Badih , Liu Liping
Published: January 2018

Injuries to the growth plate of the humerus can occur in children during motor vehicle accidents. These injuries can then lead to growth abnormalities and musculoskeletal issues as the child develops. This research was conducted to analyze and develop a solution to musculoskeletal strain caused by uneven weight distribution inherent in a case of upper limb length discrepancy. The issue is an imbalance due to the growth of a shorter humerus in the individual’s right upper limb (RUL) as the result of a prior surgery on the individual’s right humeral growth plate. This shortened RUL weighs less than the left upper limb (LUL). This effectively lowers the mass moment of inertia of the RUL, thus lowering the balancing moment on the torso. When the individual sprints during physical exercise, there is an imbalance in rotational momentum that is created between the two arms. This imbalance in momentum requires that the opposing lower limb of the shorter RUL, the individual’s left lower limb, drives harder, leading to eventual failure in the hip flexor. In order to solve this biomechanical problem, kinematic equations were developed to model the motion of a sprinter. These equations model the motions of the hands, torso, and legs. In particular, the model defines the influence of the imbalance of the upper limbs’ motion on the lower limbs’ motion, which results in a forward rotation of the torso while sprinting. To balance the rotational momentum of the upper limbs, a counter-acting weight was attached to the wrist of the RUL, minimizing the effects on the lower limb musculature. Hence, the left lower limb would not have to overcompensate for the shorter RUL’s lack of momentum. The equations were then reconfigured to account for the counterweight, and the effect was observed and analyzed. A simulation predicted an angle of tilt of up to 5.7° in the sagittal plane from the vertical. The force required to rotate the body to the normal position was 18N. This force was determined to cause a twist of 10.0° in the transverse plane from the frontal plane. While this study was conducted on an individual with a shortened right upper limb secondary to a surgical procedure, study results can readily be generalized to individuals with shortening of either upper limb secondary to other traumatic events, such as motor vehicle accidents.
Nano-Scale Binder Phase Identification in Asphalt Concrete
Authors: Faisal Hasan M. , Khan Zafrul Hakim , Tarefder Rafiqul
Published: January 2018

Asphalt concrete (AC) consists of asphalt binder and aggregate. Aggregate consists of: coarse aggregate and fines. Asphalt binder creates a coating or film around the aggregate, which is defined as the binder phase of AC. Fines are believed to be trapped inside an asphalt film or mixed with asphalt binder, creating a composite material called mastic. Thus, AC has three phases: mastic, asphalt film binder, and coarse aggregate. All these phases play major roles in performance of AC. Researchers have performed various tests on asphalt binder at micro scale to understand the macro scale behavior of AC. However, test methods developed and performed on binders, to this day, are mostly rheological shear and bending beam tests. No studies have been conducted on the compression stiffness or modulus and hardness of and binder, rather than shear and binders stiffness. In addition, the existing tests used in the asphalt area cannot be performed on binder and mastic while they are an integral part of AC. Nanoindentation tests can be performed on aggregate and asphalt binder while they are integral parts of AC. Because, in nanoindentation test, a nanometer size tip, which is smaller than binder film thickness as well as other phases. In the study, Performance Grade (PG) 64–28 was used for the study, same binder had been used afterwards to characterize asphalt and AC. A loading rate of 0.005 mN/sec, a dwell time of 200 sec and a maximum load 0.055 mN were employed in the study. In the current study 20 indentations were done on the asphalt binder sample and 100 indentations were done on AC sample, due to heterogeneity of the sample. However, to identify a specific phase in AC sample, the current study adopts the depth range technique for as same loading protocol. The depth rage of binder phase was acquired by independent indentation on same asphalt binder sample. As, asphalt is known to be a viscoelastic material that exhibits creep behavior, the creep compliance of asphalt binder was used for validation of the depth range assumption. The validation of phase identification was done by comparing the asphalt binder phase creep response while they are integral part of AC with creep response of independent asphalt binder sample under nanoindenter. The comparison shows depth resolution technique can successfully identify the binder phase of AC.
Design and Analysis of a Distributed-Deflection Sensor With a Built-In Probe for Mechanical Measurement of Soft Tissues With Curved Surface
Authors: Shen Jiayue , Palmer Xavier-Lewis , Hao Zhili
Published: January 2018

This paper presents a theoretical analysis of using a distributed-deflection sensor with a built-in probe for mechanical measurement of soft tissues with curved surface. The core of the sensor is a rectangular polydimethylsiloxane (PDMS) microstructure with a built-in probe on its top and an electrolyte-enabled resistive transducer array at its bottom. Upon being pressed against a tissue region, the built-in probe assists in avoiding extrusions and generating deformations necessary to conform to the curved surface of the tissue region. Consequently, the true mechanical properties of the tissue translate to the spatially distributed deflection in the microstructure, which registers as resistance changes by the transducer array. A simplified 1D theoretical model is created and utilized for correlating the design parameters of the sensor and the probe to the tissue parameters, in order to meet three performance criteria for the tissue-probe-sensor interaction in measurement. Costal cartilage tissues are chosen as the tissue example for analysis. The analyzed results provide the design guideline for the numerical analysis in the future for accurate determination of the design parameters for soft tissues of interest.
Fracture Toughness Measurement of Asphalt Concrete by Nanoindentation
Authors: Khan Zafrul , Faisal Hasan M. , Tarefder Rafiqul
Published: January 2018

Fracture toughness and fracture energy release rate are two important parameters to understand the crack propagation within any material. Fracture toughness of asphalt concrete (AC) is vital to explain the fatigue cracking and low temperature cracking of asphalt pavement. These two types of distresses are still unsolved issues for asphalt researchers. Measuring fracture toughness of AC is not a new phenomenon. Recently, researchers have used several techniques to measure the fracture toughness of AC. Tests like semi-circular bending (SCB) and disk-shaped compact specimen (DCT) testing have been used to measure the fracture toughness of the AC. From the SCB or DCT tests, past researchers have shown that crack in AC propagates through mainly binder and mastic phase. All these conventional tests are carried out in macro scale. It is important to understand that before propagation of these macro scale cracks, the cracks initiates at the nano/micro scale level. With the increment of the loads these nanoscale cracks become macro scale cracks and propagates through the sample. Therefore, it is important to understand the cracks at nanoscale. In this study, nanoindentation test was introduced to measure the fracture toughness of the asphalt concrete. In a nanoindentation test, the sample surface is indented with a loaded indenter. For this test, Berkovich indenter with load control method was used. A field cored asphalt concrete sample was used for this study. The sample was collected by coring at interstate 40 (I-40) near Albuquerque, New Mexico. The sample was field aged for four years. The maximum load applied in this study was 5-mn and the unloading was done at a faster rate than the loading rate. From the load-displacement curves of the nanoindentation tests, fracture toughness of the samples was measured. The unloading curve of the nanoindentation test was further used to obtain reduced modulus of the asphalt concrete using Oliver-Pharr method. In this study, fracture energy is thought of as a portion of irreversible energy. This irreversible energy is comprised of plastic energy and energy required for propagation of crack. By analyzing the load displacement curve along with the maximum indentation depth, energy release rate and mode I fracture toughness of asphalt concrete was measured.
Mechanics of Wavy Network With Diamond-Shaped Inclusions
Authors: Monsef Khoshhesab Mona , Li Yaning
Published: January 2018

In this investigation, mechanical behavior of periodic cellular solids with diamond-shaped inclusions connected via wavy network were explored. Two families of cellular solids within this category were designed based on two different geometric constraints. Auxetic effects and snap-through instability were observed for each family, respectively. The mechanical properties, including the stress-strain behavior, stiffness and Poisson’s ratio, were systematically quantified via finite element (FE) simulations. The parametric space for auxetic effects and snap-through instability was numerically identified. This study demonstrates the connection and transition between mechanical auxeticity and snap-through instability. The materials designed have potential engineering applications, such as lightweight supporting and protective foams, biomedical devices, smart composites or fabrics with switchable properties responsive to external environments.
Ball Drive Configurations and Kinematics for Holonomic Ground Mobility
Authors: Gebre Biruk A. , Pochiraju Kishore
Published: January 2018

Holonomic motion is desired for mobile ground robots and vehicles as it provides omnidirectional maneuvering capabilities, which can simplify the task of navigating around obstacles in confined spaces and unstructured environments. Mobility platforms that utilize spherical wheels are gaining popularity and interest due to the agile maneuvering and ground traversal capabilities they enable for mobility platforms. Ball-driven mobility platforms have a rich design space as various design parameters are available that can modify the physical and performance characteristics of the platforms. Various configurations for ball-driven mobility platforms are presented along with a generalized kinematic model that can be used for calculating motor velocities for a desired vehicle velocity. A naming convention is also presented in the paper for differentiating between configurations used for ball-driven mobility platforms. Metrics such as platform footprint, platform stability, and actuation force and efficiency are used to compare the configurations and to highlight some of the trade-offs associated with the selection of a configuration. Promising configurations are highlighted based on the metrics selected for the comparisons.
Parameter Identification and Closed Loop Control of a Flywheel Mounted Hovering Robot
Authors: Tatoglu Akin
Published: January 2018

A prototype of a hovering multi-terrain mobile robot platform that makes use of a flywheel for stabilization and heading control for rapid maneuverability was developed and presented in a prior paper. It was shown that flywheel stored energy could be transferred to the overall body to generate rapid angular motion once wheel is instantaneously stopped. Solution improved localization accuracy and reduced the overall sensitivity with respect to external disturbances such as non-flat terrain. In this paper, we present a feedback control system to measure dynamic parameters before and after the wheel is stopped. System is designed to follow a predefined path plan and instantaneous torque change causes oscillation after a waypoint is reached. To address this issue, we updated system with an inertial measurement unit (IMU) as a feedback sensor. Then, we investigate the feedback control of individual forward thrust vectors as well as wheel braking timing to minimize amplitude of transient response oscillation and to reduce the steady-state error to an acceptable level that differential drive fans could compensate this error and correct the heading after the rotation around a waypoint occurs. In addition to that, previous mechanical system could transfer all energy stored at once and was not adjustable. In this research, we also investigate varying amount of angular inertia generated by fans and wheel individually and together. To do so, system is modified with stronger forward thrusters. Prior to running the system with a full dynamic model with real mechanism, we implemented a simulation to empirically extract system parameters and adjust controller gains to follow a predefined path with open and closed loop control schemas with objective of minimizing localization error. Finally system is tested with real mechanism. Governing equations, simulation and empirical results comparison are presented and generated trajectories of various simulation and real world settings are listed. Test results verify that, with a closed loop control system, overshoot and total error about a waypoint can be minimized to an acceptable level at and after transient response phase.
Mechanical Performance of Paper Pulp and Wood Glue Composite
Authors: Madyira Daniel M. , Mabirimisa Takalani , Jen Tien-Chien
Published: January 2018

Due to depleting natural resources, it is necessary to develop eco-composite materials that are fabricated from sustainable and inexpensive materials such as recycled paper or cellulose-based materials. Such materials are required to meet the mechanical performance at par with traditional materials. The main aim of this study was to investigate the mechanical performance of a composite material fabricated from paper pulp and polyvinyl acetate (wood glue). It is expected that a high strength composite material may be achieved by varying the amount of paper-pulp fiber fraction from 7.5%, 10%, 20%, 30%, 40%, 50% to 60% weight. A tensile test was conducted and it was found that an increase in fiber content on the fabricated composite resulted in an increase in ultimate tensile strength and a decrease in corresponding strain. Furthermore, the material becomes more brittle at higher fiber content and conversely, more ductile at lower fiber content. The ultimate tensile strength was found to be 7.69 MPa at 60% w.t fiber and the minimum tensile strength was 0.12 MPa at 0% w.t fiber. There were no signs of fiber content limit observed in the obtained results. It was concluded that a composite of moderate strength was produced and future work is required in order to fully understand how the composite behaves at different loading conditions. However, an optimum fiber content limit will have to be determined.
Towards Computational Prediction of Wind Turbine Flow and Noise
Authors: Zhang Cheng , Basso Murilo
Published: January 2018

Wind energy is a clean, renewable, and fast-growing energy source for power generation. However, the noise issue, especially the aerodynamic noise, has become a critical obstacle in wind energy development. To determine the impact of the wind turbine noise and to guide the design and siting of wind turbines to minimize the disturbances on the local community, better understanding of the noise generation mechanisms as well as more accurate noise prediction techniques are necessary. Computational fluid dynamics (CFD) modeling of the National Renewable Energy Laboratory (NREL) Phase VI wind turbine at different wind speeds and tip pitch angles have been performed using ANSYS Fluent. The computational domain extends about 3 times of the wind turbine blade radius in the upstream direction, and 6 times the blade radius in the downstream and transverse directions. The shear-stress transport (SST) k-omega turbulence model is used. Second-order upwind schemes are used for the momentum and turbulence equations. The predicted pressure coefficients and power are in good agreement with the experimental data. The effects of wind speed and tip pitch angle on noise generation have also been investigated using the broadband noise source model. The Ffowcs-Williams Hawkings equation is also currently being used to obtain the far-field noise.
A Wearable Device for Assisting Persons With Vision Impairment
Authors: Trivedi Urvish , McDonnough Jonielle , Shamsi Muhaimen , Ochoa Andrez Izurieta , Braynen Alec , Krukauskas Cody , Alqasemi Redwan , Dubey Rajiv
Published: January 2018

Detecting humans and objects during walking has been a very difficult problem for people with visual impairment. To safely avoid collision with any object or human and to navigate from one location to another, it is significant to know how far and what kind of obstacle the user is facing. In recent years, many researches have shown that providing different vibration stimulation can be very useful to convey important information to the user. In this paper, we present our stereovision system with high definition camera to detect and identify humans and obstacles in real time and compare it with a modified version of existing wearable haptic belt that uses high-performance Ultrasonic sensors. The aim of this paper is to present the practicability of stereovision system over cane and assistive technology such as vibrotactile belt.

The study is based on two assistive technologies. The first one consists of the vibrotactile belt connected to ultrasonic sensors and an accelerometer which returns user movement & speed information to the microcontroller. The microcontroller initiates expressive vibrotactile stimulation based on sensor data. Data gathered from this technology will be used as the baseline data for comparison with our stereovision system. Second, we present a novel approach to detect the type of obstacle using object recognition algorithm and the best approach to avoid it using the stereovision feedback. Data gathered from this technology with be comparted against the baseline data from the vibrotactile belt. In addition, we present the results of the comparative study which shows that stereovision system has plethora of advantages over vibrotactile belt.
Geometrical Scaling Effects on Supersonic Inlet Performance
Authors: Askari Rasoul , Soltani Mohammad Reza , Khajeh Fard Afshin
Published: January 2018

The effects of geometrical scaling on a supersonic external compression axisymmetric inlet are investigated. Various lower and higher geometrical scales of supersonic inlet are considered as the case studies. The inlet flow is simulated numerically using RANS solver along with the SST k-w turbulence model. The numerical results are in an acceptable agreement with the NACA experimental data at free stream Mach number of 1.79 and at zero angle of attack. The results show that the static pressure distribution of the inlet flow experiences some differences for various scales especially at the regions of the flow entrance and throat area. The mean flow Mach number and the mass flow rate at the Aerodynamic Interface Plane (AIP) increases with increasing the inlet scaling. The increasing of inlet geometrical scale results in an increase in the pressure recovery. However there is no sensitive variation on the flow distortion.
Model-Based Dynamic Control of Active Thermal Management System
Authors: Van Velson Nathan , Rokkam Srujan , Truong Quang , Rasmussen Bryan
Published: January 2018

Two-phase cooling technologies, pumped two-phase and vapor compression systems in particular are highly desirable advanced thermal management systems due to the large amounts of heat transfer capabilities available via boiling flow, as well as the inherent isothermality of two-phase processes. However, two-phase heat exchangers face distinctive challenges such as flow boiling instabilities and critical heat flux. In this work, we make developments toward a simulation framework to provide a real-time capability for thermal modeling, simulation and control using embedded software capabilities of Matlab/Simulink. The framework utilizes a highly accurate finite control volume approach to model two-phase heat exchangers, semi-empirical map model for variable speed pump, and one dimensional fluid flow model for pipe. The framework is validated experimentally under transient heat loads against a pumped two-phase loop with two parallel evaporators at Advanced Cooling Technologies, Inc.
Load Tracking and Anti-Sway Control for Telescopic Rotary Crane
Authors: AbdelHamid Ahmed Y. , Abdelkader Hosam A. , Mabrouk Mohamed H.
Published: January 2018

Rotary cranes are widely used in construction operations to load and unload materials in field. However, the efficiency of the loading operation could be limited due to the crane’s slewing rotational motion that generates undesirable load sway. Various attempts of anti-sway control have been proposed for cranes however few attempts focused on the telescopic rotary crane. This paper presents load tracking and anti-sway control method that can be used to suppress the undesirable load sway during telescopic rotary crane operation. The proposed method is based on a dynamic model that has been developed to predict the sway angles, load trajectory s-curves, load cubic path trajectory, load quantic path trajectory and load zero jerk trajectory for telescopic rotary crane [1]. The operating parameters for the proposed method are obtained experimentally using scaled telescopic rotary crane prototype that is built up in lab. The results show the effectiveness of the proposed control method to achieve load tracking and anti-sway control for real time operation.
Evaluation of Interfacial Stresses in a Bilayer Shell Subjected to Intrinsic Stress
Authors: Chakraborty Anurag , Ash Jason T.
Published: January 2018

A method to computationally determine the interfacial contact pressure and shear stress in bilayers has been evaluated. The method uses “Tied-Contact Pair” conditions between two shell surfaces of a coating and a substrate in Abaqus, which constitutes a bilayer circular disk. This method was evaluated for three cases: free expansion (simply supported at the center), fixed edge, and pinned outer edge. The results were validated with previous work. The displacements obtained were typically in the range of 2–3% of the theoretical values for the linear simulations. Comparisons were made between the theoretical stress values and the radial, tangential stresses obtained at the interfacing surfaces of the bilayer from the tied model. This provided a method to perform a preliminary investigation of the interfacial stresses at the interfacing shell surface, namely the normal contact pressure and shear stress as well as the radial & tangential stresses of the constituent layers for these two shell surfaces. The non-linear SAX2 shell element type was used in this simulation. A second model which uses “Mesh-Tie Constraints” in Abaqus was also investigated. The values obtained for both these models was found to match each other. However, the difficulty with the “Mesh-Tie Constraints” method was that it did not allow the interfacial stresses to be computed explicitly; a problem not encountered with the “Tied-Contact Pair” approach. A convergence study was performed to establish convergence of the model. This method holds promise to study the complex interfacial stress developed in multi-layered coatings typically encountered for Physical Vapor Deposition (PVD) processes.
Stochastic Simulation of Diffusive Behavior of Macromolecules Encapsulated in Electrospun Fibers: A Parametric Study
Authors: Stabile Christopher , Yan Karen Chang
Published: January 2018

Electrospinning is a versatile technique to produce nano/micro fibers with controlled morphology in terms of fiber diameter, alignment etc. With multiple configurations including single axial, co-axial, tri-axial, and co-spinning, this method enables researchers to produce electrospun (ES) fibers with bioactive molecules encapsulated in order to mimic the extracellular matrix for tissue engineering applications. It is of great interest to understand and control the release rate of the bioactive molecules to examine the effects of bioactive molecules such as growth factors on cells. We developed a stochastic simulation method based on the Fick’s diffusion equation to model the diffusive behaviors of macromolecules encapsulated in electrospun fibers. This paper presents a detailed parametric study including 1) the effects of inherent random variation within the samples such as distribution of diameters, initial concentration, diffusion constants, and 2) the effects of volume of release medium. MATHEMATICA is used to carry out the simulations. The computed results are compared with experimental data in the literature.
Design of Intelligent Control for an Air Conditioning System Solar Using an Absorption Refrigeration Cycle
Authors: Cardona-Gil Jorge A. , Osorio Marisol
Published: January 2018

Among different strategies available technologically to reduce energy consumption and environmental impact in buildings, there is the use of new thermal-operated air conditioning systems. An available alternative is absorption refrigeration systems, which can operate with renewable energy sources such as solar energy, and use environmentally friendly refrigerant substances.

In Colombia, this type of systems has not been investigated thoroughly nor have carried out developments, because the field of solar energy is emphasized in the use of thermal energy, to be used on a refrigeration cycle that allows to condition an environment of a determined compound, and besides that, this air conditioning going to achieve through intelligent control, it has not been subject of considerable advances, neither in the part of applied research, nor its implementation. According to this, the idea is to use developments of these systems that have been simulated and implemented in other countries, including Spain, for the start in the UPB with research, development and implementation of those after making a literature review about the systems.

To develop the aforementioned system, a comprehensive literature review of the technologies has been made to be implemented in terms of automation and control. A simulation in the TRNSYS software of the system to be implemented in a building on the campus of the UPB, which requires air conditioning for the comfort of the people who inhabit, is eveloped. The system will be regulated by a controle system that receives information from various parts of the plant with temperature and flow sensors. To carry out the control of this system, classical control techniques are going to be used for some water systems that constitute the demonstrative installation, but for the part of chilled water and air conditioning, intelligent control techniques will be handled, which allows to meet the needs of the air conditioning system that is intended to be implement, as this part is quite complex for the management of different variables. This system will operate automatically acting on valves, pumps, fans, fan-coil and/or mats of water (they act as radiant walls) for correct operation by previously established set points [1].
Modeling of the Electrical Resistance of TCP Muscle
Authors: Wu Lianjun , Tadesse Yonas
Published: January 2018

A recently emerged artificial muscle that is created by transforming a sewing thread or fishing line through a process of twisting, coiling and annealing has a great potential application in sensing, actuation or energy harvesting. Extensive experimental investigations along with modeling have been carried out to further understand the twisted and coiled polymer (TCP) muscle. The TCP muscle has a large actuation stroke and long life cycle, and is easy to produce with low cost. Incorporation of TCP muscles into sensor application will advance the combined muscle-sensor integrated system development. We explored the strain sensing principle of TCP muscle based on its change in electrical resistance during actuation. In this paper, we present a geometrical model to describe the principle based on the relationship between the electrical resistivity, temperature and length. Moreover, a series of experiments were carried out to correlate the time domain input and output relationships as well as to verify the model.
Additive Manufacturing of Magnetically Loaded Polymer Composites: An Experimental Study for Process Development
Authors: Nagarajan Balakrishnan , Eufracio Aguilera Alejandro F. , Qureshi Ahmed , Mertiny Pierre
Published: January 2018

Material jetting is an additive manufacturing technique that allows to produce three-dimensional solid parts without tooling and with minimum material wastage. In this context, magnetically loaded polymer composites with oriented magnetic particles are promising for many electrical and electronic applications. In this study, permanent magnet based alignment configurations were evaluated and compared in terms of different magnetic flux density using the finite element method. The particle alignment in cured droplet specimens and the stability of magnetically loaded polymer droplets deposited on a substrate were characterized for a material jetting based additive manufacturing process. Particle alignment and droplet deformation under the influence of the magnetic field was captured using real-time optical microscopy. The influence of rheological additives in controlling droplet stability in the magnetic field and mitigating particle settling were studied through experiments. The primary goal of this research was to identify parameters that facilitate high particle alignment, and material combinations that enhance droplet stability and mitigate particle settling. This fundamental research serves to enhance the understanding of processes and material behaviour for material jetting based additive manufacturing.
Measuring Displacement Within a Transfemoral Socket Using Marker-Based Optical Tracking System: Static Tests
Authors: Salazar-Salgado Sara , Rendón-Vélez Elizabeth
Published: January 2018

In lower limb amputees, the comfort and fit of the prosthesis determine whether the user wears or not the prosthesis, fact on which a successful rehabilitation depends. The prosthetic fit is highly related with the relative motion between the socket and the residual limb (i.e., displacement). Displacement has been measured in static and dynamic position and between several surfaces such as skin-socket, liner-socket, bone-socket using various instruments. Marker-based optical tracking system is one of the most recent instruments used for measuring displacement between the socket and the residual limb that solves many of the constraints faced by other measurement instruments. Two options have been reported on the literature for using this instrument: transparent test socket with 2D marker and definite socket with cavities and 3D marker, both facing different limitations. The objective of this study is to evaluate these two options using Marker-based optical tracking system in order to give recommendations and contribute to the use of this method on future research.

Two sockets were used for the study: a transparent socket and a definite socket with and without cavities. Six trials were performed using both sockets with three types of markers located inside the socket: 2D circular, 3D hemisphere and 3D sphere. VICON motion capture system was used to detect the visibility of the markers at knee flexion angles (0° to 30°).

The results showed that all markers were visible from 15° to 30° knee flexion in all trials. The 2D marker presented difficulty of detection on knee angles from 0° to 10°, especially on the final socket without cavities. 3D hemisphere marker was seen almost all along the knee angles. 3D-sphere marker was visible in all positions, but the relatively large size of these markers may not be adequate to measure displacement.

Using the definite socket with the 2D circular and 3D hemisphere markers could be a good option to measure displacement between the residual limb and socket. Using this socket will be closer to reality than doing it on the transparent one. Additionally, the size of the 3D-hemisphere is relatively small, it may not drastically change the behavior between surfaces and as it is a 3D marker it can be better seen by the cameras.

Further tests should be done with patients walking all along the path in order to assess if the markers visibility is the same on static and dynamic trials.
A Comparative Finite Element Analysis of Hart-Smith Hyperelastic Model Under Uniaxial, Planar and Equi-Biaxial Tension
Authors: Thakkar Rohan , Czekanski Aleksander
Published: January 2018

The classical phenomenological compressible Hart-Smith model expressed in exponential-logarithmic terms of stretch invariants is compared with substantial hyperelastic models available in Abaqus. It is implemented in Abaqus Explicit using a customized user subroutine. Compressible Hart-Smith model together with selected acclaimed models available in Abaqus are evaluated under uniaxial tension, equi-biaxial extension and planar tension modes of deformations. The required material constants are determined from a simple uniaxial tension test. In order to investigate mode-independent characteristics of considered models, predictive planar tension and biaxial extension simulations are performed using the material constants derived from a uniaxial tensile test. Obtained numerical results are validated with respect to classical experimental data for natural rubber reported by Treloar.
Optimal Path Planning of Robot Type Wheelchair Transfer Device
Authors: Yun JungHwan , Kang OhHyun , Park TaeMun , Kong JaeHo , Seok MinGeun , Yi Hak , Lee SangRyong
Published: January 2018

It is difficult for a disabled person or an elderly person to transfer a wheelchair to a vehicle before and after driving because a general car can’t store the wheelchair. Therefore, in order to solve such difficulties, a vehicle having a wheelchair transfer device capable of automatically transferring the wheelchair between the trunk and the driver’s seat is required. This paper proposes a robot type wheelchair transfer manipulator having these functions and evaluates the proposed transfer system through optimal path analysis.