bluuebunny/crossref_metadata_2025 huggingface dataset:
High Resolution Overset Structured Grid RANS Simulations of Flow Past a Surface Mounted Cube Using Eddy Viscosity Closure Models
Authors: Goldbach Marc C. , Uddin Mesbah
Published: January 2019

While Reynolds-averaged simulatons (RAS) have found success in the evaluation of many canonical shear flows, and moderately separated flows, their application to highly separated flows have shown notable deficiencies. This study aims to investigate these deficiencies in the eddy-viscosity formulation of four commonly used turbulence models under separated flow in an attempt to aid in the improved formulation of such models. Analyses are performed on the flow field around a wall mounted cube at a Reynolds number of 40,000 based on the cube height, h, and free stream velocity, U0. While a common occurrence in industrial applications, this type of flow constitutes a complex structure exhibiting a large separated wake region, high anisotropy, and multiple vortex structures. As well, interactions between vortices developed off of different faces of the cube significantly alter the overall flow characteristics, posing a significant challenge for the commonly used industrial turbulence models. Comparison of mean flow characteristics show remarkable agreement between experimental values and turbulence models which are capable of predicting transitional flow. Evaluation of turbulence parameters show the general underestimation of Reynolds stress for transitional models, while fully turbulent models show this value to be overestimated, resulting in completely disparate representations of mean flow structures between the two classes of models (transitional and fully turbulent).
Numerical Investigation of Heat Transfer in Tissues During Therapeutic Hyperthermia
Authors: Tiari Saeed , Mahdavi Mahboobe , Chauhan Kinjalkumar , Piovesan Davide
Published: January 2019

A numerical analysis is conducted to study the thermal behavior of human healthy and cancerous tissues during magnetic nanoparticle hyperthermia treatment. A transient multi-layer two-dimensional model is developed using commercial CFD package, ANSYS-FLUENT 18.1. The impact of therapeutic heat generation rate and various tissue cooling conditions on the thermal response of the tumor and normal tissues are investigated. It was found that the tumor temperature is not affected by different cooling conditions while the temperature of healthy tissues around tumor is significantly impacted. The results also demonstrated that the effective tumor temperature can be achieved in approximately ten minutes by using therapeutic heat generation rate of 150 kW/m3 in all three cooling conditions.
Design and Development of an Unmanned Underwater Vehicle (UUV) in the Form of a Cuttlefish
Authors: Cherangara Subramanian Susheelkumar , Le Thao , Olson Jason , Bhat Sandesh , Redkar Sangram
Published: January 2019

Current methods of unmanned underwater locomotion do not meet stealth, robustness and efficiency. This work discuses about designing a Bioinspired UUV or Unmanned Underwater Vehicle that uses an undulating fin approximating to that of a cuttlefish fin locomotion. This propulsion method has higher maneuverability and ability to navigate while leaving its surroundings relatively undisturbed as compared to other propeller based systems. Mathematical models and control algorithms describing the complicated locomotion have been developed, and a simulation model is used to verify the theoretical results. This design of UUV can be utilized for underwater data collection and military applications without hampering the underwater wildlife.
Comparing Contact Stress Estimates of Some Straight Bevel Gears With ISO 10300 Standards
Authors: Osakue Edward E. , Anetor Lucky
Published: January 2019

The pitting resistance of straight bevel gears, like other gears, is commonly assessed on the basis of the contact stress in a gear mesh. A new contact stress model for straight bevel gears is used to estimate the contact stress in some gearset designs and compared with predictions from ISO 10300 bevel gear standards. In the cases considered, the new model contact stresses defer from the ISO values in the range of 13% to 33%, with the ISO predictions generally on the higher side. These deviations appear to be somewhat high but not unreasonable because of obvious differences in the two models. The ISO standard uses the mid facewidth cone radius in its contact stress model while the new model uses the cone backend radius which is larger than the mid facewidth cone radius. Another contributing factor is that the load service factor values evaluated from ISO methods are generally higher than those of the new model values, based largely on American Gear Manufacturers Association (AGMA) methods. It should be noted that the power ratings for all the design cases studied are below 10 kW.
Finite Element Modelling of TBC Failure Mechanisms by Using XFEM
Authors: Bostancı Safa Mesut , Gürses Ercan , Çöker Demirkan
Published: January 2019

Thermal Barrier Coatings have been widely used in modern turbine engines to protect the nickel based metal substrate from the high temperature service conditions, 1600–1800 K. In this study, some of the failure mechanisms of typical Air Plasma Sprayed Thermal Barrier Coatings (TBC) used in after-burner structures composed of three major layers: Inconel 718 substrate, NiCrAlY based metallic bond coat (BC) and Yttria Stabilized Zirconia (YSZ) based ceramic top coat (TC) are investigated. Investigation of the cracking mechanism of TBC in terms of design and performance is very important because the behavior of TBCs on ductile metallic substrates is brittle. To this end, four-point bending experiments conducted in Kütükoğlu (2015) is analyzed by using the Extended Finite Element Method (XFEM). All the analyses are conducted with the commercial finite element software ABAQUS. Three different models with varying TC and BC thicknesses are studied under four-point bending. It is observed that multiple vertical cracks are initiated in the TC. Cracks initiate at the top of YSZ and propagate through the whole TC. It is observed that the average crack spacing increases with the increasing thickness of the TC. Numerical results are found to be consistent with the experimental results. In other words, the average crack spacing for three different models are similar with the experimental results.
Solar Photovoltaic Power Plant Development for a Desert Climate
Authors: Alanezi Abdullah , Naraghi Mohammad H.
Published: January 2019

The present work develops design guidelines for a photovoltaic power plant to shave peak electricity demand in an arid climate, which cover approximately 1/3rd of earth land mass and a good portion of this climate is in the Middle East and North Africa. In a typical desert climate, such as the Arabian Peninsula a large portion of the electricity consumed is due to the use of air conditioning units during hot sunny days. In the present work the energy consumption pattern of a typical building in an arid area is studied. Additionally, overall regional grid power demand in Tabuk located in Northwest of Saudi Arabia is studied. Guidelines for development of solar plants (i.e., panel ordinations) are presented to shave off the peak demand. It is determined that for most desert climates the peak electricity demand is between 2:00–5:00PM during summers.
General Correlation for Heat Transfer During Two-Component Gas-Liquid Flow in Horizontal Pipes
Authors: Shah Mirza M.
Published: January 2019

Heat transfer to two-component gas-liquid mixtures is needed in many industries but there is lack of a well-verified predictive method. A correlation is presented for heat transfer during flow of gas-liquid non-boiling mixtures in horizontal tubes. It has been verified with a wide range of data that includes: tube diameters 4.3 to 57 mm, pressures from 1 to 4.1 bar, temperatures from 12 to 62 °C, gravity < 0.1 % to 100 % earth gravity, liquid Reynolds number from 9 to 1.2E5, and ratio of gas and liquid velocities from 0.24 to 9298. The 946 data points from 18 sources are predicted with mean absolute deviation of 19.2 %. The same data were compared to several other correlations; they had much larger deviations.
Flow Characteristics of Nitrogen (N2) in Micro-Channels of Printed Circuit Heat Exchanger (PCHE)
Authors: Shin Jeong-Heon , Yoon Seok Ho , Choi Jun Seok
Published: January 2019

Experiment and simulation studies were performed to investigate the flow characteristics of pressure-driven Nitrogen flow in the micro-channels of Printed Circuit Heat Exchanger (PCHE). The core of the PCHE was made using diffusion bonding method with ten stainless steel 316L plates, where hemispherical 1 mm in diameter channels were chemically etched. On one of the plates, four-teen more channels, 1 mm in diameter, were milled to make pressure taps to measure local pressure drops. Then, one inlet tube and four-teen tubes for pressure tabs were attached by welding on the top and sides of PCHE core, respectively. The PCHE was connected to Nitrogen tank with pressure regulator, Coriolis flowmeter and differential pressure gauge, and data was acquired with DAQ system.

By varying the velocity of Nitrogen gas from 1 to 35 m/s, differential pressure drops were measured between two different locations. The local pressure drops were analyzed theoretically and pressure loss coefficients could be calculated in straight and serpentine channels, respectively. In addition, simulation work using ANSYS Fluent was also performed to understand flow characteristics especially at corners of channels.
Development of Three-Dimensional DC Electric Field Stimulation Bio-Reactor for Axonal Outgrowth Enhancement
Authors: Tanaka Shohei , Sakiyama Ryota , Yamamoto Koji , Morita Yusuke , Nakamachi Eiji
Published: January 2019

Numerous studies of electrical stimulation effects on the nerve regeneration have been carried out. However, there were very few investigations which adopt the 3D culture that mimics the in vivo environment. In this study, we designed and fabricated a new 3D direct current electric field (DCEF) stimulation bio-reactor and investigated the effectiveness on the axonal outgrowth enhancement. We searched an optimum structure using the finite element (FE) analyses to obtain a uniform DCEF in the culture region. A measurement result of DCEF strength showed an agreement with FE results. The rat phenocromocytoma cells (PC12) were disseminated in the collagen gel and 3D culture was performed. We observed the morphologies of cell bodies and neurites using the multiphoton excitation fluorescence microscope (MPM). Both increases in 11.3% of mean axonal length and in 4.2% of axogenesis rate, under the condition of 5.0 mV/mm on 6 hours a day for 4 days, were obtained. Further, there was a tendency of longer connecting distance between cell bodies in the DCEF group than one in the Control group. As a result, we validated the efficacies of our stimulation, both for the axonal extension and the neural network generation, using our newly developed bio-reactor.
Cellular Automaton and Finite Element Hybrid Simulation to Predict Axonal Extension Enhancement of Nerve Cell Under Mechanical Stimulation
Authors: Takeda Shota , Tomita Yoshihiro , Nakamachi Eiji
Published: January 2019

In the clinical application, the mechanical stimulation against the damaged brain tissue is adopted as the kinesitherapy for the nerve regeneration. Nevertheless, the fundamental mechanism to repair the damaged nerve cell has not been revealed yet. Recently, the cyclic stretch stimulation has been reported as the efficacious treatment method to enhance the axonal extension for regenerative therapy of injured nerve cell. Therefore, we try to develop a new cellular automaton (CA) finite element (FE) hybrid method to predict the axonal extension and nerve network generation, which can evaluate the effect of stretch stimulation on the cell body, axon and dendrites.

In the FE results, the stress concentration occurred at the junction of the axon and cell body. The maximum stress value in the axon was 8.2 kPa which is about twice as large as that of the cell body. CA adopted to predict the morphological evolution of nerve cells under the mechanical stimulation. It was confirmed that the stress affects to accelerate the axonal extension as experimentally suggested. As a result, our CAFE can be employed to simulate the axonal extension and generation of nerve network system under the condition of extra cellular mechanical stimulation.
Development of Telepresence Teaching Robots With Social Capabilities
Authors: Zhang Mingshao , Duan Pengji , Zhang Zhou , Esche Sven
Published: January 2019

A telepresence robot is a device that allows people to participate in video conferences on a moveable platform from a remote location. The users can remotely control the robot’s motion and interact with each other through a video screen. Such systems, which were originally designed to promote social interaction between people, have become popular in various application areas such as office environments, health care, independent living for the elderly, and distance learning. Although there is ample published empirical work surrounding the use of telepresence and computer-mediated communication in education, few studies have examined telepresence robots in the classroom. Although some studies have indicated positive learning experiences and outcomes in education facilitated by telepresence robots, further research is needed to better identify the possible effects such approaches have on student learning and perceptions of instructor credibility.

In order to maximize the students’ learning outcomes, it is very important to improve the usability of the telepresence robot platform for both the instructors and the students. In addition, the instructor credibility is also crucial to the overall learning experience. In the research presented here, an innovative remote teaching platform, which includes features of telepresence robots and social robots (which are autonomous robots that interact and communicate with humans by following social behaviors and rules associated with their roles), is developed. It is believed that telepresence robots equipped with the capabilities provided by social robots can improve the credibility of the instructor and the usability of the education platform, both of which contribute to the students’ overall learning outcomes.
Defects Evaluation of Selective Laser Melting Stainless Steel 316 Parts Using Positron Annihilation Lifetime Measurement
Authors: Yao Hong , Katona Ryan , Zhou Jianren , Islam Md I , Raush Jonathan , Lu Fengyuan , Guo Shengmin
Published: January 2019

Alloy parts fabricated by the selected laser melting (SLM) additive manufacturing process generally contain many defects. Non-destructive Positron Annihilation Lifetime Spectroscopy (PALS) measurements were applied to evaluate these defects. The two-component positron lifetime method was used to analyze the evolution of two types of defects, mono-vacancy and vacancy cluster.

Stainless steel 316 SLM samples were prepared using two sets of SLM processing parameters. For SLM samples, the temperature effect of heat treatment was examined by PALS. The effect of plastic deformation is also examined using PALS.
A Performance Comparison for Electric and Hydraulic Motors
Authors: Al-Mudhafar Mohammed , Manring Noah D.
Published: January 2019

Many off highway machinery companies have begun to transfer their products from hydraulic drives to electric drives, but there is not a clear study found in the literature that shows a comparison between these two drives in order to demonstrate the benefits for this transformation. In this paper, a nondimensional comparison between electric and hydraulic motors is made in terms of losses, efficiency, and energy consumption. The loss analyses for both types of motors is conducted and an efficiency map for these motors is produced. The energy consumption is compared for both motors for the same load during a common duty cycle.
Improvement of Joint Integrity in MIG Welded Steel: A Review
Authors: Odiaka Timothy , Madushele Nkosinathi , Akinlabi Stephen
Published: January 2019

Metal Inert Gas Welding is one of the most widely used welding methods in manufacturing industries. A significant challenge in any welding process is the achievement of high quality welds. This has led to a host of welding techniques designed with the goal of maintaining weld integrity by improving its mechanical and structural properties.

This study looks at the application of various methods to improve the integrity of welded steel joints with attention to MIG welding. The systematic approach to the review considered in detail, the works done by numerous researchers in improving the integrity of welded steel joints through parametric optimization. This included several research works which adopted Taguchi’s Design of Experiment method. A few other notable methods of improving weld quality apart from parametric optimization were also reviewed and were not exclusive to MIG welding.

The study showed that the bulk of research embarked on, in the improvement of weld integrity involved parametric optimization. This also proved to be the simplest method. However, some other suggestions such as Post Weld Heat Treatment, Pulsed Current, Hybrid welding and Vibratory Welding were discovered to be alternative means of improving weld integrity. The use of reinforcing powders was also discovered, and it was suggested that the quality of MIG welded steel joints could be improved by using titanium alloy powder as weld joint reinforcement.
Modeling the Wind Turbine Profiles Assuring the Maximum Lift Force With Low-Noise Operation for Variable Wind Velocities
Authors: Radulescu Victorita
Published: January 2019

The paper presents a new solution for the wind turbine profile shape modeling based on the concept of the maximum lift force, capable to be produced at different values of the wind velocities. The profile is designed and realized in accordance with the new concept emerged in the last decade, on the operation of the wind turbines with maximum lifting force. The purpose is to provide a low-noise during operation because a negative effect on the medium and long-term operation of the wind turbines (wind farms) is the noise that affects the flight of birds, terrestrial animal life, and especially human communities. Various sources generate independent acoustic emissions on wind profiles, such as the turbulent flow, the interaction of the turbulent boundary layer area of the trailing edge, the flow separation, and the boundary layer separation of vortices formed in the zone of the trailing edge. There is also considered the influence of the apparent wind on the incidence variation of the profile. In order to maintain an optimum angle of attack relative to the wind velocity, a fixed blade inclination must increase its speed to be proportional to the wind. Thus, to maximize the aerodynamic performance, the rotor must spin faster when the wind intensity increases. Measurement of the acoustic signal requires electronic devices that operate on electric signals obtained from the conversion of the pressure variations in voltage or variations in electrical current. The noise caused by the turbulent flow is generated primarily by the sharply pointed leading edge and cannot be diminished. There are presented some numerical results correlated with the measurements made in the field.
Influence of Non-Newtonian Rheology on Mass Transfer From a Biofluid in Separated and Reattached Flows
Authors: Hammad Khaled J.
Published: January 2019

Influence of the rheological model selection on the flow and mass transfer behavior of human blood in a separated and reattached flow region is investigated. Newtonian and non-Newtonian hemorheological models that account for the yield stress and shear-thinning characteristics of blood are used. The conservation of mass, momentum, and species equations as well as the Herschel-Bulkley constitutive equation are solved numerically using a finite-difference scheme. A parametric study is performed to reveal the impact of flow restriction and rheological modelling on blood-borne oxygen exchange with the confining walls. The wall mass transfer rates within the separated and reattached regions display a strong dependency on the used hemorheological model. Newtonian and non-Newtonian models result in a peak wall mass transfer rate within the recirculation region. However, non-Newtonian models that account for the yield stress and shear-thinning effects predict a substantial, highly localized, drop in the wall mass transfer rates of oxygen, at the reattachment point.
Ionic Liquids As Additives to Cutting Fluids to Reduce Machine Tool Friction and Wear
Authors: Ferri Chris , Lizarazo Sydney , Troise Michael , Iglesias Patricia
Published: January 2019

In manufacturing processes, the cost of tooling contributes to a significant portion of operating costs. Several papers have been dedicated to various improvements on tool life, including monitoring the effect of temperature conditions and flood cooling. Flood cooling is not economical, so research has also been done to investigate minimum quantity lubrication and the effects of different additives, such as nanofluids. Another additive, ionic liquids, have become popular in tribological studies because they have unique properties that allow them to form ordered molecular structures, which is ideal in lubrication. Research has proven ionic liquids to be effective in reducing wear and friction coefficients. Currently, utilizing ionic liquids specifically to reduce tool wear has been almost exclusively limited to titanium and steel applications. The goal of this study is to improve tribological performance of the subtractive manufacturing process using ionic liquid add-ins to widely available machine shop coolants and oils. A series of reciprocating ball-on-flat experiments will be conducted using a 1.5mm diameter 250 Chrome Steel G25 ball and 6061-T6 aluminum disk to simulate cutting conditions often seen in manufacturing processes. 6061 Aluminum is an alloy commonly seen in machine shops and large-scale manufacturing scenarios because of its versatile material properties and wide availability. The tests were run at constant sliding distance, velocity and load. The lubricating mixtures were prepared by adding 5 wt % of a phosphonium based ionic liquid, Trihexyltetradecylphosphonium bis(trifluoromethylsulfonyl)amide ([THTDP][NTf2]), to the base fluids Trim Sol™ emulsion fluid and Mobilmet™ 766 high performance neat cutting oil. The addition of the ionic liquid to both base lubricants (oil and coolant) increased the friction coefficient (18.60% and 4.89%, respectively) while the wear volume was reduced (28.75% and 7.84%, respectively). The results for the oil provided evidence that the ionic liquid did have an effect to reduce wear, however, the same conclusion could not be drawn for the coolant.
An Experimental Study of Periodic Motions in a Duffing Oscillator
Authors: Guo Yu , Reyes Zeltzin , Reyes Abigail , Luo Albert C. J.
Published: January 2019

In this paper, the experimental dynamics of a Duffing oscillatory system are studied for periodic motions. A Duffing oscillatory circuit is developed for the experimental study of periodic motions on the bifurcation trees. The coexisting asymmetric periodic motions are obtained experimentally. The analytical periodic motions in the Duffing oscillator are presented for comparison with experimental results. Because of hardware and data leakage of experimental instruments, the experimental result accuracy is much lower than the analytical results of periodic motions. To improve the experimental results accuracy, the high quality hardware and instruments should be adopted and the high resolution data acquisition systems should be adopted.
Vibratory System Identification of 3D Printed Cantilever
Authors: Crifasi Daniel , Ergle Matthew , Özdeş Hüseyin , Perkins Edmon
Published: January 2019

Although 3D printing has become a widespread method of fabrication, the vibratory properties of thermoplastic composites are poorly understood. This is, in part, due to the anisotropies introduced by the 3D printing process, the composite materials used, and the geometry. In this study, an attempt has been made to characterize the vibratory response of a 3D printed thermoplastic cantilever, in order to determine the damping ratio and natural frequency. The cantilevered beams were 3D printed, with a range of varied parameters. These parameters include the inclusion and exclusion of continuous carbon fiber reinforcement, as well as the three orthogonal build directions. Impact tests and frequency sweeps were used to gain information about the vibratory response of these cantilevers. This information was used to model the effects of the carbon fiber and anisotropy introduced by the different build parameters. During the experiments, a high-speed camera was used to record the response of the cantilevers. These videos were then post-processed with image analysis tools to quantify the response. Then, a point near the tip of the cantilever was used as the time-dependent variable for a reduced order model. By proceeding in this described method, the damping ratio and natural frequency of the system may be written as a function of the build parameters.
Utilizing Advanced Manufacturing Technologies to Develop a Reconfigurable Lumbar Puncture Training Model
Authors: Kalajdzic Besim , Urbanic Ruth Jill , Khayat Andre , Farias Anna
Published: January 2019

The lumbar puncture (LP) procedure is a diagnostic procedure that is performed to identify the root cause behind symptoms which can often be caused by various diseases or infections. Currently, medical students will either perform LPs directly on live patients with only theoretical knowledge of the procedure, or they will first be trained using unrealistic models that give a poor representation of the procedure. Traumatic taps (poorly performed LPs) were found to occur in approximately 15% of adult patients, and 35% in children. To reduce these complications, it is necessary that medical students receive the best training possible, which can be made possible through utilizing advanced design and manufacturing technologies. The training mannequin should be flexible, have realistic tissue force resistance, and be reconfigurable for different body types, and age groups. A parametric CAD model is developed that can be modified to represent key structural dimensions from infant to adults, force testing is conducted on a cadaver to determine the puncture forces, and more realistic ‘tissue’ materials are derived via experimentation as the existing training models have noticeably different resistance characteristics. The individual elements for a new training mannequin solution have been determined. Additive manufacturing processes can readily fabricate the vertebrae and pelvis elements, as well as the specialty molds. A final model assembly, and field testing, needs to be performed.
Vulnerability Analysis of Link-Weighted Shanghai Metrorail Transit Network
Authors: Zhang Yanjie , Saadat Yalda , Zhang Dongming , Ayyub Bilal M. , Huang Hongwei
Published: January 2019

With the degradation of metrorail facilities and the increase in network size, it is urgently needed to perform vulnerability assessment to ensure the safe operation of the metro system. In this paper, a link-weighted network model is proposed by considering the physical interval length between neighboring metro stations as link weight factor. Firstly, the metro network was essentially mapped into a bipartite topological diagram that consists of nodes denoting metro stations and links representing metro routes including any tunnels or bridges. After analyzing the network for its complexity level, it was revealed that the metro network topology can be appropriately constructed by using the Space L method. On this basis, multiple characteristic indexes of the network were calculated to characterize network topology structural features. We then tested the state of Shanghai metro network under different failure scenarios by removing a fraction of nodes from the network. Quantitative vulnerability analyses were conducted according to the change in the topological structure of Shanghai metro network and the change in the corresponding global network efficiency due to disruptions. Finally, both the network efficiency of link-weighted and unweighted Shanghai metro network topology were calculated and compared. This study has identified the vulnerable metro stations, which could provide support for the reasonable resource allocation of maintenance work and the decision-making in emergency treatment after failure. In order to increase the adaptability to emergencies and improve the operational efficiency, it was proposed that during the planning, construction, and operation of the metro system, the management and protection of the vulnerable stations should be given increased attention.
Preliminary Heat Transfer Simulation Model of a Novel Dynamic Thermal Ablation Probe
Authors: Nakao Joseph , Han Yen-Lin
Published: January 2019

Recent advancements in medical technology have included engineering thermal ablation probes, a minimally invasive cancer treatment aimed to heat up cancerous cells. Currently, probes meant to treat hepato-cellular carcinoma (HCC), commonly known as liver cancer, are limited to tumors up to 5 cm across. Consequently, the effectiveness of ablation treatment decreases considerably for tumors beyond this range. Unlike most probes that are stationary, a novel design by Han et al. intends to extend beyond this range via a dynamic probe. We present a mathematical heat transfer model in which the spatial- and time-dependent heat source probe is represented by an ad hoc combination of traveling wave solutions. Specifically, 1D and 2D simulated results for the heat transfer of the dynamic probe are presented in this paper for selected input parameters. This preliminary mathematical model paves the way for optimizing the dynamic thermal ablation probe in future work.
Mechanical Design of Magnetic Gearboxes Optimized for Assembly
Authors: Modaresahmadi Sina , Nichols Casey , Williams Wesley
Published: January 2019

Magnetic gearing is a developing technology that utilizes magnetic forces to transmit torque through a system. Unlike traditional gears that rely on teeth engagement to transmit motion and torque, interacting magnetic fields in a magnetic gear transfer the torque with no contact area required. Early magnetic gearbox designs stemmed from an electromagnetic design, however, at larger scales the assembly process as well as electromagnetic design drives the overall mechanical design, due to high magnetic forces and stresses during the assembly. The development of magnetic gearboxes involves the optimization of the assembly process, the electromagnetic design and the mechanical performance to achieve a design that is robust, efficient, manufacturable, and economical. Each of these attributes is necessary to advance the technical readiness for applications as varied as wind turbines or robotics. These qualities were sought in the design of two new magnetic gearboxes which have been manufactured and tested. The mechanical design of the multistage gearbox established a repeatable assembly process that could be upscaled without compromising the structural integrity of the components. Design variants were simulated and tested to limit bending and shear stresses in the gearbox, whilst maintaining the electromagnetic performance of the system. The mechanical design of the modular magnetic gearbox established a new rotor design where manufacturability and configurability were improved to make the gearbox ideal for applications that require varying gear ratios.
Arterial Wall Motion and its Dynamic Modeling for Arterial Stiffness and Damping
Authors: Wang Dan , Vahala Linda , Alberts Thomas , Hao Zhili
Published: January 2019

The pulsatile pressure in an artery is accompanied by the radial motion of the arterial wall. In this paper, the governing equation of the radial wall motion is first derived, indicating that longitudinal stretching of the arterial wall plays a critical role in the radial wall motion. Based on the derived equation and time-harmonic nature of its radial motion, the arterial wall is modeled as a second-order dynamic system. A microfluidic-based tactile sensor is used to acquire the arterial pulsatile pressure waveform, which is used to represent the radial displacement of the arterial wall. Consequently, the 1st-order and 2nd-order derivatives of the radial displacement are the wall velocity and wall acceleration. In the context of time-harmonic vibration, the key features in the radial displacement and its two derivatives are interpreted to obtain the elasticity and viscosity of the arterial wall: spring stiffness and damping coefficient in the circumferential direction. Pulse signals at radial artery (RA) and superficial temporal artery (STA) on seven healthy human subjects are measured and processed to estimate the two physical properties of the arterial wall. The measured difference in the physical properties between the two arteries and among the seven subjects validates the feasibility of the proposed dynamic modeling of the radial wall motion to capture the physical properties of the arterial wall, and at the same time demonstrates the necessity of subject-specific and artery-site-specific measurements.
Simulation of Film Cooling Heat Transfer and Simulation Improvement With a Modified DES Turbulence Model
Authors: Yu Feiyan , Yavuzkurt Savas
Published: January 2019

Modeling the heat transfer characteristics of the highly turbulent flow in gas turbine film cooling is important for better engineering solutions to the film cooling system design. URANS, LES, DES and modified DES models capability in simulating film cooling with a density ratio of 2.0 and blowing ratio of 1.0 are studied in this work. Detailed comparisons of simulation results with experimental data regarding the near-field and far-fields are made. For near field predictions, DES gives decent prediction with a 21.4 % deviation of centerline effectiveness, while LES and URANS have deviation of 33.6% and 51.2% compared to the experimental data. Despite good predictions for near field, DES under predicts the spanwise spreading of counter rotating vortex pair and temperature field, therefore it over predicts the centerline effectiveness in the far field. To compensate for this shortcoming of DES, the eddy viscosity in the spanwise direction is increased to enhance spanwise-diffusion of the cooling jets. The modified DES prediction of overall centerline effectiveness deviates 12.4% from experimental data, while LES, unmodified DES and URANS predictions deviate 10.8%, 31.9% and 46.9%. The modified DES model has adequate predictions of vortices evolutions which URANS modeling lacks and consumes significant less computational time than LES. It can be said that the modified DES model results in satisfactory film cooling modeling with a moderate computational cost and time.
Effect of Process Parameters on the Electrically-Assisted Sintered Iron-Copper Powder Metals
Authors: Ragai Ihab , Schwabenbauer Matt , Eser Seray , Müller Michael
Published: January 2019

Electric-current-assisted sintering (ECAS) is a novel process that can potentially replace the conventional sintering method. It is hypothesized that the process can reduce the sintering time and can be used in situ; thus, can be more cost effective. The purpose of this research is to investigate the effect of direct current on the sintered properties of iron-copper powder metal. Experiments were conducted at various conditions to determine the optimal process parameters for this particular powder metal. The parameters investigated were electric current levels and energizing time. Experiments also included sintering the powder using a conventional furnace. Samples from both types of experiments were compared to determine the metallurgical differences due to the sintering process. Mechanical and microstructure examination were conducted to aid in determining the feasibility of ECAS.
A Numerical Study on Rotational Tube Flaring Process
Authors: Nikhare Chetan P.
Published: January 2019

A substantial increase in demand on the sheet metal part usage in aerospace and automotive industries is due to the increase in the sale of these products to ease the transportation. However, due to increase in the fuel prices and further environmental regulation had left no choice but to manufacture more fuel efficient and inexpensive vehicles. These heavy demands force researchers to think outside the box. There are many advanced manufacturing processes to produce optimized part are single and double point incremental forming, Reuleaux forming, hydroforming, explosive forming, electrically assisted manufacturing. In this project, a numerical study on rotational tube flaring process will be studied. Tube flaring is one of the most commonly used processes under tube forming. In this process, a conical tool contacts and forces the end of the tube while another end of the tube is fixed. This is called conventional flaring process. In contrast to this process, a tool rotational technique was utilized for this work. The rotation and the feed of the tool will be analyzed to have the best formability of the tool. The strain path and failure will be analyzed. The strain and thinning pattern will be discussed.
A Hybrid Energy Harvesting System Based on Solar Radiation and Mechanical Vibration
Authors: Rahman M. Shafiqur , Chakravarty Uttam K.
Published: January 2019

Hybrid energy harvesting is a concept that can be applied to improve the performance of the conventional standalone energy harvesters. In this study, a hybrid energy harvesting device is presented that harvests energy from solar radiation and mechanical vibration by simultaneously combining the photovoltaic, piezoelectric, electrostatic, and electromagnetic mechanisms. The device consists of a bimorph piezoelectric cantilever beam having Lead Zirconate Titanate crystal layers on top and bottom surfaces of an Aluminum substrate. Two sets of comb electrodes (capacitors) are attached on two sides of the substrate. A permanent magnet is attached at the tip which oscillates within a stationary coil inside a casing. The exterior surface of the casing is covered by organic photovoltaic panel that captures energy from illumination. All the segments are interconnected by an electric circuit to generate combined output when subjected to solar radiation and mechanical vibration. Results for power output are obtained at the first resonance frequency of the beam with a common optimum load resistance. As the power outputs of all the mechanisms are combined, a high power efficiency can be achieved by the proposed hybrid energy harvester.
Real Time Loading Test Rig for Flight Control Actuators Under PHM Experimentation
Authors: Chiavaroli P. , De Martin A. , Evangelista G. , Jacazio G. , Sorli M.
Published: January 2019

The article deals with the architecture, performance, and experimental tests of a test bench for servo-actuators used in flight controls. After the state of the art on the subject, the innovative architecture of the built bench is described, in which flight control actuator under test and load actuator are not in line but mounted perpendicularly.

The model of the bench actuating systems is then presented, consisting of the servo-controlled hydraulic actuator, load cell, speed transducer, angular position transducer of the coupling and pressure transducers. For each of these components the nonlinear multi-physics mechatronic model is described, according to the adopted solutions. The adopted force control algorithm is discussed, showing the integrative compensation on the action line and proportional-derivative on the feedback, with speed feedforward.

The experimental tests carried out on the bench under stalled conditions are also presented, whose results concerning time and frequency responses are compared with those obtained through the linearized and non-linear numerical model.

Finally, the non-linear models of the flight control actuator under test, controlled in position, and of the loading servo-actuator of the bench are joined together, and the results of various simulations are described.
Experimental Investigation on Flow Field in a Rotating Channel With a New TR-PIV System
Authors: Zhou Shengjun , Li Haiwang , Tao Zhi , You Ruquan , Duan Haoyu
Published: January 2019

In the current study, the influence of different rotation conditions on the flow behavior is experimentally investigated by a new system which is designed for time-resolved PIV measurements of the smooth channels at rotation conditions. The Reynolds number equals 15000 and the rotation number ranges from 0 to 0.392 with an interval of 0.098.

This new time-resolved Particle Image Velocimetry system consists of a 10 Watts continuous laser diode and a high-speed camera. The laser diode can provide a less than 1mm thickness sheet light. 6400 frames can be captured in one second by the high-speed camera. These two parts of the system are fixed on a rotating disk. In this case, the relative velocity of flows in the rotating smooth square channel can be measured directly to reduce the measurement error. This system makes high-speed camera close to the rotating channel, which allows a high resolution for the measurements of main stream. In addition, high accuracy and temporal resolution realize a detailed analysis of boundary layer characteristics in rotation conditions. Based on this system, experimental investigation has been undertaken. Results are presented of the evolution of velocity and boundary layer thickness at various rotation numbers and different circumferential positions.
System Identification of Hydrokinetic Energy Harvester Using Flow Induced Oscillations
Authors: Saxton Ralph , Patra Soumyadip , Xiros Nikolaos I. , Bernitsas Michael M. , Sun Hai
Published: January 2019

Using data series obtained by experiments at the Marine Renewable Energy Laboratory of the University of Michigan, a Data-Driven Model is constructed for further investigation of the Process Dynamics and Control System Design and Configuration. This will enable advances in hydrokinetic energy harvesting using Vortex Induced Vibrations (VIV) and galloping, or more generally, Flow Induced Oscillations (FIO). Typically in such energy converters, one or more multiple bluff bodies, such as cylinders are suspended on springs in a water flow (currents, tides, rivers). In commonly encountered flows, oscillations are induced to the bluff rigid bodies due to vortex shedding in their wake, or due to lift instabilities in galloping, or both. These phenomena are dependent on stiffness, damping, mass ratio and the resulting vortex shedding frequency. The experiments in the cases investigated generated position signal recordings for one or two cylinders used as bluff bodies in FIO in a cross-flow. The position signals are used to set up a dynamic model. The model equation helps in gaining insight into the dynamics and underlying physics of the modeled FIO and can be used for Control System Tuning and Verification.
Design, Installation, and Validation of a Data Acquisition System
Authors: Liu Yucheng , LeClair Andrew , Doude Matthew , Burch Reuben F.
Published: January 2019

A data acquisition system along with a sensor package was designed and installed on an existing mechanically-controlled cargo tractor to gather more data on their usage patterns. The data collected through the developed system include GPS route, vehicle speed and acceleration, engine state, transmission state, seat occupancy, fuel level, and video recording. The sensor package was designed and integrated in a way that does not interfere with the driver’s operation of the cargo tractor. Cellular network connectivity was employed to retrieve sensor data so as to minimize human effort and maintain typical usage patterns of the outfitted cargo tractors. Testing and validation results showed that the developed system can correctly and effectively record data necessary for further analysis and optimization. A fuel usage analysis was then completed using a chassis dynamometer based on the collected data. The collected data will significantly promote cargo tractor activity simulations in order to facilitate optimizing work flow at large industrial facilities and improving energy efficiency.
VR-Mediated Teleoperation With Glove-Like Interfaces
Authors: Chen Kun , Dahal Prawesh , Avagyan Mariam , Huang Kevin
Published: January 2019

This paper presents a method for teleoperation using virtual reality (VR) headsets and glove-like interfaces, and evaluates the proposed system with a preliminary user study. For effective teleoperation, it is imperative that the operator possess adequate feedback regarding the remote device state. This work utilizes commodity VR technology to replicate critical remote task features in a purely software/virtual environment from sensor data. The 3D visual feedback is immersive yet simplified to reduce sensory burden — only relevant features are reflected. The system is designed and executed on a real robotic platform, and preliminary operation is encouraging. Moreover, high dexterity VR gloves provide an intuitive and natural interaction for the operator, as the user may present fluid and motion commands without the use of an unnatural game-controller. A user study was conducted to compare performance along several relevant metrics between use of glove-like and game controller interfaces for VR teleoperation. These metrics include time to completion, path length, and jerk as a measure of path smoothness. The results of said study suggest strongly that teleoperator performance improves with the adoption of glove-like interfaces.
Canal Design for SLA Printing of Closed Geometries
Authors: Petrosky Erin , Schmitz Anne
Published: January 2019

Infection after joint arthroplasty is the most devastating complication that can occur. As a result, antibiotic eluting biomaterials have been created using three-dimensional printing to prevent these infections. The goal of this study was to investigate the ability of an SLA printer to create accurate internal geometries capable of carrying antibiotics. The maximum amount of unwanted polymer was 0.9 g, which did not vary with resin viscosity or internal void size. This suggests SLA printing may have potential to create accurate, drug eluting biomaterials in a wide variety of polymers and geometries.
Development of a Low-Cost Mechanical Model of a Human Head
Authors: Foltz Grace , Tillotson Elizabeth , Todd Beth A.
Published: January 2019

In recent years, interest has developed in Chronic Traumatic Encephalopathy (CTE) and the related concussions that occur in sports at both professional and amateur levels. Subsequently there is interest in developing new types of athletic helmets to both absorb energy to detect and reduce concussions. To test these helmets, an appropriate head form must be used that will fit the helmet and also exhibit the dynamic properties of the human head. While much effort has gone into creating biofidelic heads containing instrumentation for automotive crash testing, these heads can cost upwards of $10,000. The goal of this project is to create a head form for a few hundred dollars with the appropriate dynamic properties for testing linear and angular accelerations of a helmet.

The specific goals of this project are to create a head form with the following characteristics: 1) External size and shape that will properly fit a hockey helmet; 2) Weight representative of an adult head; 3) Robust enough to withstand a thousand impact tests. The manufacture of the head form and the verification that the design goals are described.