bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation Method of Surface-Rigidity Distribution in Elastic Body by Surface-Probing
Authors: Fujita Shohei , Sakuma Atsushi
Published: January 2020

Elasticity distributions in structure is one of the typical physical quantities that it is desired to measure nondestructively. Indentation testing is a useful method for the nondestructive measurement methods; however, devices are necessary to evaluate the distribution of elasticity. In this report, a technique to evaluate the elastic distribution in solid is introduced by the information obtained from a simple indentation device. The evaluation is based on Hertzian contact theory that is applied to calculate elasticity from force measured by this indentation device. However, the non-uniform nature of elasticity distribution makes it difficult to apply Hertzian theory. As a solution to this difficulty, a correcting method of elasticity is discussed by analyzing the variation of force information obtained from the device. This correction depends on the method for determining the correction factor decided by the area of elastic range distributed in the solid; this decision is numerically defined by finite element method (FEM). The usefulness of this correction method is confirmed by evaluating the hardness distribution of wood grain. Trees are a representative material with hardness distribution, whose mechanical characteristics depend deeply on wood grain. Therefore, evaluating the ability of elasticity distribution in wood grain has been checked by the correction method discussed in this report. Then, for the problem related to evaluation based on basic Hertzian theory, the expected result can be obtained using wood grain size coefficient and the specification of the probe. However, it is also necessary to examine to the choice of device specifications such as probe dimensions because the elasticity of wood is relatively high and any measured information will have high sensitivity in elastic analyses. Those recommendtion are discussed by showing the devices developed for this evaluation in this report.
Particle Swarm Optimization Method for Hyperelastic Characterization of Soft Tissues
Authors: Ramzanpour Mohammadreza , Hosseini-Farid Mohammad , Ziejewski Mariusz , Karami Ghodrat
Published: January 2020

Hyperelastic constitutive models such as Ogden and Mooney-Rivlin are commonly used for nonlinear characterization of soft materials and especially biomaterials such as brain tissue. The parameters of these models are usually found by curve-fitting to the experimental or in some cases, the numerical data. Most of the times, common non-linear least square curve fitting method known as Levenberg-Marquardt (LM) is employed for this purpose. In this paper, we show that the result of this method is highly dependent to the initial guesses. In some cases, the approximated curve-fitting solution can be very close to the experimental data, however, the hyperelastic parameters can be very different to the actual ones despite the fact that a very good curve-fitting solution (high coefficient of correlation) may be achieved. To overcome this problem, we demonstrate the application of a derivative free (black box) optimization method called particle swarm optimization (PSO) for hyperelastic characterization of nonlinear materials using least square method. Using multiple search agents in PSO makes this method highly inclined to end up with global optimum points in the search space. In this study, the hyperelastic parameters for Ogden and Mooney-Rivlin hyperelastic models are found for bovine brain tissue by using the experimental uniaxial compression test data. The PSO method yields high coefficient of correlation for curve fitting and its results is comparable to the LM method in terms of accuracy of parameters. It is concluded that PSO can be successfully used for nonlinear hyperelastic characterization of soft materials such as brain tissue.
Probabilistic Design and Uncertainty Quantification of the Structure of a Monopile Offshore Wind Turbine
Authors: Nispel Abraham , Ekwaro-Osire Stephen , Dias João Paulo , Cunha Americo
Published: January 2020

Despite the increasing demand for offshore energy, structural components of offshore wind turbines (OWT), such as the tower and foundation, are considered the most critical parts of the turbine. In fact, uncertainties regarding load conditions, soil and structural properties highly undermine the OWT structural reliability. In this scenario, in order to obtain more accurate results, rigorous probabilistic analyses are necessary. In this study, a probabilistic analysis of the dynamic response of a monopile OWT is conducted by using a systematic uncertainty quantification (UQ) framework to deal with the uncertainty assessment of the model input parameters. The proposed dynamic model computes the dynamic response of the turbine due to wind and waves loads on the monopile structure utilizing a simple cantilever beam analytical model. The distributions of the model input parameters are determined using (1) nonparametric statistics for a large dataset, and (2) the maximum entropy principle for a small dataset. Monte Carlo simulations are performed to propagate the uncertainties of the model inputs and to determine the system reliability expressed in terms of their probability of failure for the serviceability limit state design criterion. Finally, to demonstrate the shortcomings of traditional approaches that assume standard distributions to model uncertainties, a UQ approach modeling the uncertainties of the parameters using normal distributions is contrasted with our framework. From the results, significant differences between the distribution shape and values of the probability of failure can be observed; thus, it demonstrates the importance of developing probabilistic frameworks with systematic UQ to have more realistic approximations of the reliability of the OWT structure.
A Numerical Study of Natural Convective Heat Transfer From Two-Sided Inclined Square Plates Having a Finite Thickness
Authors: Manna Rafiq , Oosthuizen Patrick H.
Published: January 2020

Simultaneous natural convective heat transfer from the top, bottom and side surfaces of two-sided inclined square plates having various thicknesses has been numerically investigated. The aim of this work is to determine whether the plate thickness has a significant influence on the heat transfer rates from the plate surfaces when the plate is inclined to the horizontal and to determine how the heat transfer rate varies with this angle of inclination. The upper, lower and side surfaces of the plate have been assumed to be isothermal and at the same temperature which is higher than that of the surrounding fluid. The range of conditions considered is such that laminar, transitional, and turbulent flow occur over the plate. The numerical solution has been obtained using the commercial CFD solver ANSYS FLUENT©. In this study, results have only been obtained for the case where the plate is exposed to air. Inclination angles of between 0 and 40 degrees from the horizontal and plate dimensionless thicknesses (thickness-to-side length ratios) of between 0 and 0.3 have been considered. Variations of the mean Nusselt number with Rayleigh number for the top surface, bottom surface, side surface and that averaged over all heated surfaces of the plate for various inclination angles and for various plate dimensionless thicknesses have been obtained.
Hydrolytic Aging in Rubber-Like Materials: A Micro-Mechanical Approach to Modeling
Authors: Bahrololoumi Amir , Dargazany Roozbeh
Published: January 2020

The effect of hydrolytic aging on mechanical responses of Rubber likes materials, in particular, Mullins effect and the permanent set has been modeled. Hydrolytic aging is considered as the result of the competition between two phenomena (1) chain scission and (2) cross-link scission/reformation. Both phenomena were modeled and thus, the strain energy of the polymer matrix is written with respect to three independent mechanisms; i) the shrinking original matrix which has not been attacked by water, ii) conversion of the first network to a new network due to the reduction of the crosslinks, and iii) energy loss from network degradation due to water attacks to ester groups. The model is validated with respect to a set of experimental data. Besides accuracy, the simplicity and few numbers of fitting parameters make the model a good choice for further implementations.
ROS Based Adjustable Resolution Compact 3D Scanner
Authors: Dion Scott , Tatoglu Akin
Published: January 2020

This research study aims to design and develop a compact multi-sensor 3D scanning system for a mobile robot which can detect object types. Sensor suite is equipped with a 3D Lidar with 360-degree field of view and a stationary camera mounted on top of a 2DOF turret. The sensor data is fused to generate a 3D point cloud. Mechanism is required to sweep the 3D space in pitch and roll axes. While servo controller can adjust generated point cloud resolution — and scan duration —, camera images can also be registered to generate a panoramic image of the environment followed by radial distortion corrections. System can generate variable density scans for specific application such mapping or self-driving. This study is the perception portion of our full-scale self-driving golf cart research project of Autonomous Mobile Robotics Research Group.
Virtual Reality Laboratory: Green Robotic Ultrasonic Welding
Authors: Chiou Richard Y. , Mauk Michael G. , C. Husanu Irina , Tseng Tzu-Liang (Bill) , Sowmithran Sowrirajan
Published: January 2020

This paper describes recent developments in an ongoing project to develop a series of virtual reality (VR) based robotic ultrasonic welding laboratory simulations, designed to impress upon users the importance of proper laboratory safety procedures and the potential consequences of not doing so. Robotic ultrasonic welding virtual reality laboratory is developed as an educational project and laboratory component for undergraduate engineering curricula. Ultrasonic welding is a relatively fast, clean process that does not require adhesives, binding agents, solders, fluxes, or solvents. However, it can only be done either by an experienced welder or a welding robot since it is difficult to weld due to high-frequency mechanical vibration and complex welding path. This paper explores the use of virtual reality simulation of industrial robots and its application in the field of industrial design and automation with lab-on-a-chip devices. With a virtual reality based welding simulator, learning ultrasonic welding can be made easier and faster. Accordingly, educational approaches that combine and integrate multiple disciplines afford more efficient and effective use of time and resources. A concluding section discusses the student learning outcomes during this project.
Modelling Damage Accumulation During Cyclic Loading in Elastomeric Gels With Interpenetrating Networks
Authors: Morovati Vahid , Dargazany Roozbeh
Published: January 2020

Double network (DN) elastomers are a class of reinforced gels that benefit from a significantly high stretch-ability and toughness. However, DN gels lose their toughness due to the accumulation of damage under cyclic loading during their lifetime. While recent advances in the process and characterization of the DN gels have led to significant improvements in their properties, our understandings of the accumulated damage mechanisms within the material remain sparse and inconclusive. Here, a physically motivated constitutive model is presented for DN gels subjected to a high number of cyclic deformations, which will eventually approach a steady-state after thousands of cycles. The model can be particularly used to elucidate the inelastic features, such as permanent damage during deformation of each cycle. The observed damage may be induced from the chain scission, chain slippage, or polymer relaxation. Therefore, irreversible chain detachment and decomposition of the first network due to its highly cross-linked structure are explored as the underlying reasons for the nonlinear stress softening phenomenon. The model is validated against the experimental tests. The model contains a few numbers of material constants and shows good agreement with cyclic uni-axial tensile test data.
Quantifying Mechanical Properties of PCL-Based Nanofiber Mats Using Atomic Force Microscopy
Authors: White Allison , DeVos Amanda , Elhussein Amr Elamin , Blank Jack , Nair Kalyani
Published: January 2020

Polymeric scaffolds aid in creating an environment for cell proliferation and differentiation in tissue engineering applications by acting as temporary artificial extracellular matrices (ECMs) for cells to form functional tissue. Many studies have reported that cell behavior can be significantly affected by the physical and chemical properties of a given scaffold. Therefore, the mechanical and structural properties of these scaffolds must be characterized. Polymeric solutions, such as polycaprolactone (PCL), have been electrospun into nanofiber mats to be used as cell scaffolds. Polycaprolactone (PCL) is a biocompatible polymer and is commonly used in tissue engineering applications; however, PCL is hydrophobic, which makes it difficult for cells to adhere to the mat. Coating the PCL-based mats with collagen, a naturally occurring protein with hydrophilic properties, may improve cell adhesion to the scaffold. The collagen coating may also alter the mechanical properties of the nanofiber mats. In this study, the effect of collagen coating on cell adhesion and proliferation are investigated using alamarBlue tests. Additionally, the mechanical and surface properties of PCL-based nanofiber mats are investigated using a Nanosurf C3000 atomic force microscope (AFM). One batch of PCL mats were coated with collagen, while the uncoated mats were used as controls. The cell behavior and material property values obtained from the uncoated PCL and collagen-coated PCL mats were analyzed and compared. The results of this study suggest that collagen does significantly influence the cell proliferation and material properties of PCL-based mats and that further studies should be conducted to better understand the effects of the nanoscale properties of the PCL-based mats on cell adhesion.
Study on Model Evolution Method Based on the Hybrid Modeling Technology With Support Vector Machine for a SOFC-GT System
Authors: Chen Jinwei , Sun Shengnan , Chen Yao , Zhang Huisheng , Lu Zhenhua
Published: January 2020

The mechanism models of solid oxide fuel cell–gas turbine (SOFC-GT) systems are very useful to analyze the detail thermodynamic performance, including the internal complex mass, heat and electrochemical processes. However, several characteristic parameters in the mechanism model are difficult to be estimated accurately due to the unknown offset. As a result, it is difficult for the mechanism model to maintain high accuracy during the full operating cycle. In this paper, a model evolution method based on hybrid modeling technology is proposed to simulate the thermodynamic performance more accurately during the full operation cycle. A hybrid model framework of SOFC-GT system is designed to evolve the mechanism model. The electrochemical characteristic of SOFC is identified and evolved by a data-driven model based on least squares-support vector machine algorithm (LS-SVM) rather than a mechanism electrochemical model. Firstly, the prediction performance of the electrochemical LS-SVM model is compared with the test data. The maximum error of prediction is only about 1.776 A/m2, and the prediction accuracy reaches 99.998%. Then the hybrid model, coupled with the LS-SVM electrochemical model from the mechanism model, is developed to simulate the thermodynamic performance of SOFC-GT system. The off-design performance of the SOFC-GT system is analyzed by the hybrid model and mechanism model. In addition, the comparison results show that the hybrid model can accurately predict the SOFC-GT system performance. The maximum error is less than 2.2% at off-design condition. In consideration of its significant advantages combining data-driven model and mechanism model, hybrid model is a powerful candidate for accurate performance simulation during full operation cycle.
Mechanical Design of Distributed Solar Sail Deployment Systems
Authors: Li Ni , Kim Salla , Lin Jason , De La Torre Benjamin , Wong Manhong , Shen He , Patel Vimal
Published: January 2020

Solar sailing has been increasingly considered for future space missions as an alternative method of propulsion, since it uses radiation pressure exerted by sunlight on a large mirrored surface for thrust and it does not require propellants such as chemicals or compressed gasses. For decades, single solar sail designs and deployment mechanisms have been studied and implemented in several CubeSats with the purpose of propulsion or deorbiting. Recently, a distributed four sail design has been proposed. The distributed four sails would have the potential to not only provide the spacecraft with propulsion force for space travel, but also control the attitude of the spacecraft by the coordinated motion of the four sails. Considering the large dimensions of the sails, it is necessary for the solar sails to be effectively stowed before launch and then deployed in a controlled manner in space. In this paper, the mechanical design of a deployment system that can stow and deploy four independent triangular solar sails with the ability to rotate after deployment will be presented. To demonstrate the effectiveness and the feasibility of the design, a prototype has been developed and validated through theoretical analysis and experimental tests.
An Evaluation of the Effects of Team Projects and Augmented Reality on Student Learning in Sustainable Building Science
Authors: Lin Cheng-Xian , Pradhananga Nipesh , Vassigh Shahin
Published: January 2020

Sustainable building design and construction involves complex systems that require multidisciplinary teams from engineering, construction, and architecture, to design and analyze the systems at every stage of the process during the building’s life cycle. However, students who are the future work force are often trained in different disciplines across different colleges. When these students are grouped together to work on the building design and analysis, learning in a multidisciplinary environment could be both beneficial and challenging due to the difference in their background. In this paper, we report our experience and analysis of data examining the learning effectiveness of the undergraduate students from three cross-college departments in architecture, construction, and engineering. Using pre- and post-semester tests on selected building science problems, we have investigated how the student’s understanding of building science had changed through team projects. Particularly, for mechanical engineering students in the design of thermal/fluid systems classes, we analyzed whether a cross-college multidisciplinary team could do better as compared to a disciplinary-specific team within the same class. We also examined the potential effects of emerging technology, augmented reality, on student learning in the same team environment. It was interesting to find that students’ learning in discipline-specific teams can be improved as in the multidisciplinary teams, due to the challenges in the complexity of the projects.
A 5-cm2 PEM Fuel Cell Gas Diffusion Layer Experimental Study and Scanning Electron Microscopy Visualization
Authors: Montoya Segnini Jose , Carbajal Gerardo
Published: January 2020

The present experimental study aims to determine the effect of two different gas diffusion layers in the performance of a 5-cm2 proton exchange membrane (PEM) fuel cell. The gas diffusion layers consisted of a carbon cloth gas diffusion (GDL-CT) and a non-woven carbon paper (Sigracet 25 BC, Sigracet 29, and BC Sigracet 35 BC). The effect of the GDL parameters on the fuel cell performance was evaluated by the polarization curve. Based on the polarization curve results, it was confirmed that the carbon cloth gas diffusion layer had a better performance than the non-woven carbon. Different temperatures, hydrogen flow rates and inlet pressures were tested. Images from the scanning electron microscopy were obtained to visualize the internal structure of a carbon paper GDL and a carbon cloth GDL; it was observed different surface structures between them.
A Study of Concussions in Women’s Lacrosse
Authors: Honarmandi Peyman , Toscano Lisa , Calicchia Michael , Diaz Miguel , Kaishian Emma , Stallings William
Published: January 2020

Concussions in athletes can be brought on by a hit to the head or sudden change in direction of the neck or head. This causes the brain to oscillate in the cranium hitting against the skull. Two common scenarios that result in a concussion in women’s lacrosse were studied: lacrosse ball to head contact and stick to head contact. Current Manhattan College student athletes on the Women’s Lacrosse team were used to obtain data regarding the average velocity of the ball, stick, and players. A pitching machine was utilized to accurately control the velocity of the ball when striking the dummy’s head to obtain the time of impact. The first step of this research is computational, as the collision scenarios were modeled and analyzed from a mechanical point of view. A linear acceleration value was obtained for a wide range of potential impact scenarios between the ball and player. When a linear acceleration greater than 50g is sustained, a concussion is likely to occur. The maximum linear acceleration calculated in this research was roughly 75.46g for ball to head contact and 62.3g for stick to head contact. Therefore, it was concluded that there is a high risk that a player will suffer a concussion in these scenarios. The results highlight the dangers in a gameplay setting, which indicates a potential need for alteration to game play style or regulations.
Design, Modeling and Analysis of a Novel Reconfigurable Wheeled Robot With Elastic Actuated Mechanism
Authors: Attia Tamer , Furukawa Tomonari
Published: January 2020

This paper presents the novel design of a Reconfigurable Wheeled Robot (RWR) with an Elastic Actuated Mechanism (EAM) capable of improving the robots dynamic stability on irregular terrain by controlling the RWR’s ground clearance, body roll and pitch angles with optimally distributing the vertical force on each tire. The EAM mainly consists of a linear actuator connected in series with a shock absorber. Four sets of the EAM are used to create different robot configurations to adapt to the terrain. The RWR dynamic model is derived for analyzing the dynamic behavior using the linear actuators positions and speeds as inputs to determine the resulting ground clearance, body roll, and pitch angles. Sensors are integrated onboard the RWR to calculate the robot’s states in real-time for use in feedback control. Results obtained in real environments reveal the effectiveness of the proposed novel design in stabilizing the RWR on irregular terrain.
Positive Intelligence Education for Unleashing Student Potential
Authors: Tyagi Pawan
Published: January 2020

Student attitude towards learning is strongly dependent on the hidden traits and habits they develop during the growing up period. Based on circumstances many students live in an individualistic mindset and perceive rather permanent misconceptions about the surrounding and opportunities. This paper focuses on providing positive intelligence training to college student to equip them with the necessary knowledge to not only unleash their talent but also to enable other students to give the highest performance. This paper focuses on an experiment under which 22 students in the senior level design of energy system course were exposed to the fundamental aspects of positive intelligence. Every student was tasked to demonstrate the depth of understanding about the positive intelligence and then apply it to group members to understand the strength and weakness. Most of the students expressed satisfaction that they were able to understand their attitude and behavior that they found as an impediment in their progress. After positive intelligence training, several students exhibited an increased maturity level and many students expressed higher degree of empathy towards their team members.
An Initial Framework for Implementation of Industry 4.0 in the High Technological Manufacturing Sector in Southern California
Authors: James Sagil , Shetty Anupam
Published: January 2020

The fourth industrial revolution, also known as Industry 4.0 is a new paradigm that is significantly influencing several manufacturing industries across the globe. Industry 4.0 synchronizes concepts such as Smart Manufacturing, Smart Factory, and the Internet of Things with existing factory automation technologies in order to improve value in manufacturing by monitoring key performance indicators and creates value in all manufacturing related aspects. Currently, several industries have started early initiatives of implementing these technologies. As the industries are evaluating their readiness for implementing the Industry 4.0 concepts, there are several challenges which need to be addressed including high initial investment, lack of standardization, data security and lack of skilled labor. A strategic roadmap towards implementing the Industry 4.0 paradigms is still unclear in the industry as well as in academia. This research develops an initial framework for the effective implementation of Industry 4.0 in the high technology manufacturing sectors in the Southern California region. The results of this study are expected to provide a platform to expand the opportunities of Industry 4.0 further and facilitate worldwide adoption.
Effect of Graphene Nanoplatelet Addition on the Conductive Behavior of Solution Mixing Processed Polylactide Biopolymer Nanocomposites
Authors: Zhang Qi , Mertiny Pierre
Published: January 2020

The fabrication of highly thermally and electrically conductive polymer materials is of interest for multiple applications, for example, in electronics packaging and biosensors. Polylactic acid (PLA), a commercially available and biodegradable polyesters, is widely used and studied since it is considered a environmentally friendly alternative to petrochemical-based synthetic polymers. In the present study, graphene nanoplatelets (GNP) reinforced PLA composites were prepared via solution blending followed by a compression molding process. Various physical and thermo-mechanical analyses were performed with the prepared composites. For instance, the electrical conductivity of PLA/GNP composites at various filler loadings was determined using four-point probe resistivity measurements. An electrical conductivity of 0.1 S/cm was achieved at a GNP loading of 12 wt%. Using the hot-disk transient plane source method, anisotropic thermal conductivity properties were evaluated. An in-plane and through-plane thermal conductivity of 0.87 W/mK and 0.58 W/mK was achieved with the addition of 6 wt% GNP, which is a nearly twofold and over fourfold increase compared to neat PLA, respectively.
Evaluation and Characterization of ASS316L at Sub-Zero Temperature
Authors: Kosaraju Satyanarayana , Kalluri Anil , Singh Swadesh Kumar , ul Haq Ahsan
Published: January 2020

Austenitic Stainless-Steel grade 316L is one among the significant ASS grades which is most commonly used in various industry sectors. It has excellent corrosion resistance in ordinary atmospheric and also in more arduous environments such as salt water and environments where resistance to chloride corrosion is required. Whilst performing well when exposed to relatively high temperatures, this grade of Austenitic Stainless steel also maintains its strength and toughness at sub-zero temperatures, making this an excellent choice for various applications in industries sectors such as Marine, general construction, and water treatment. Therefore, present study focused on evaluating the mechanical properties such as ultimate tensile strength (UTS), yield strength (YS) and strain hardening exponent (n) are evaluated based on the experimental data obtained from the uniaxial isothermal tensile tests performed at an interval of −25 °C from 0 °C to −50 °C and at three orientations (0, 45, 90) degrees to the rolling direction and cross head velocity (3, 5, 7) mm/min were chosen. A total of 27 experiments have been planned based on design of experiments to conduct experiments. A mathematical model for the prediction of ultimate tensile strength (UTS), yield strength (YS) and strain hardening exponent (n) was developed using process parameters such as temperature, orientation and cross head velocities. Results have shown that mechanical properties can be predicted with a reasonable accuracy within the range of process parameters considered in this study.
A Conductive Cooling Scheme for Bone Augmentation of the Proximal Femur With PMMA: An Experimental and Finite Element Study
Authors: Bakhtiarinejad Mahsan , Farvardin Amirhossein , Chamani Alireza , Armand Mehran
Published: January 2020

The rate of one-year mortality after osteoporotic hip fracture in elderly is reported to be more than 20%. Hip augmentation using polymethylmethacrylate (PMMA) is an alternative preventive approach for patients at the highest risk of osteoporotic fracture. Excessive injection volumes of PMMA however may introduce the risk of thermal osteonecrosis. We have previously proposed a Finite element (FE) simulation to estimate the bone temperature elevations after cement injection in three key locations and demonstrated an agreement between the simulation results and the temperature measurements during the experiment. Previous study showed that the maximum temperature-rise measured at the hip surface is 10°C. The aim of this study is to introduce a cooling approach to reduce the PMMA’s curing temperature after cement injection during hip augmentation. For this purpose, we perform a conductive cooling experiment with a metallic K-wire attached to an ice-water bath. We also create a finite element simulation model for the proposed cooling system to estimate the peak temperature reduction and compare the simulation results with experimental data. Simulation results demonstrate the decrease of 80% of peak curing temperature during PMMA polymerization; similarly, sawbone experiments also show that on average the peak temperature has been reduced 64% when cooling system is integrated to the hip augmentation procedure.
Experimental Study of the Effect of Nanoparticle Concentration on Thermo-Physical Properties of Molten Salt Nanofluids
Authors: Tiznobaik Hani , Shin Donghyun
Published: January 2020

Increased in thermo-physical properties of molten salt nanofluids have been reported. These findings makes molten salts nanofluids one of the most promising thermal energy storage media. One of the main application of these types of materials are in concentrated solar power plants. In this study, an investigation is performed on nanofluids specific heat capacity mechanisms in order to provide a reasonable description of the specific heat capacity enhancement of nanofluids. Then, a comprehensive experiments are performed on the effects of nanoparticles concentration on the specific heat capacity and materials characterization of molten salt nanofluids. This study is performed to analyze the optimum amount of nanoparticle and find the way to maximize the effects of nanoparticle on thermophysical properties of molten slat. Different molten salts nanofluids with varying nanoparticles concentration were synthesized. The specific heat capacities of mixtures were measured by a modulated scanning calorimeter. Moreover, the material characterization analyses were performed using scanning electron microscopy to investigate the micro-structural characterization of different nanofluids.
Performance Improvements of Krylov Subspace Methods in Numerical Heat Transfer and Fluid Flow Simulations
Authors: Blomquist Matthew , Mukherjee Abhijit
Published: January 2020

In recent years, advancements in computational hardware have enabled massive parallelism that can significantly reduce the duration of many numerical simulations. However, many high-fidelity simulations use serial algorithms to solve large systems of linear equations and are not well suited to exploit the parallelism of modern hardware. The Tri-Diagonal Matrix Algorithm (TDMA) is one such example of a serial algorithm that is ubiquitous in numerical simulations of heat transfer and fluid flow. Krylov subspace methods for solving linear systems, such as the Bi-Conjugate Gradients (BiCG) algorithm, can offer an ideal solution to improve the performance of numerical simulations as these methods can exploit the massive parallelism of modern hardware.

In the present work, Krylov-based linear solvers of Bi-Conjugate Gradients (BCG), Generalized Minimum Residual (GMRES), and Bi-Conjugate Gradients Stabilized (BCGSTAB) have been incorporated into the SIMPLER algorithm to solve a three-dimensional Rayleigh-Bénard Convection model. The incompressible Navier-Stoke’s equations, along with the continuity and energy equations, are solved using the SIMPLER method. The computational duration and numerical accuracy for the Krylov-solvers are compared with that of the TDMA. The results show that Krylov methods can improve the speed of convergence for the SIMPLER method by factors up to 7.7 while maintaining equivalent numerical accuracy to the TDMA.
Miniaturized Ultrasound Transducer Composed of a Composite of Multiple Piezoelectric Stacks
Authors: Kim Howuk , Wu Huaiyu , Goel Leela , Jiang Xiaoning
Published: January 2020

This paper aims to develop a miniaturized ultrasound transducer for intravascular thrombolysis, which requires a transducer with high mechanical index (> 0.3) and a long focal distance (> 2.0 mm). To meet this need, a composite of a multi-pillar piezo stack (MPPS) transducer was designed and fabricated by using PZT-4, conductive epoxy, soft elastomer, and a metallic concave lens. The simulation results showed the predominant extensional mode at around 0.92 MHz. The −6 dB focal distance was elongated by 150% from that of the common single-pillar piezo stack (SPPS) transducer with the same aperture. The acoustic pressure was improved by 8.2 dB at the focal zone. Next, the experimental results showed the peak-to-negative pressure of 1.92 MPa under 120 Vpp input, which was sufficient to cause the inertial cavitation of microbubble contrast agents. The −6 dB focal distance reached up to 3.4 mm which was a significant improvement compared to the conventional SPPS transducer. The developed intravascular transducer will be employed for the microbubble-mediated ultrasound thrombolysis to reduce the treatment time.
Design of Bolted Preload Electromechanical Impedance Monitoring Device for CubeSat
Authors: Zhang Zihan , Li Jiacheng , Du Fei , Xu Chao
Published: January 2020

With the rapid development of long-term orbiting spacecraft, deep space exploration and reusable carriers, spacecraft structures increasingly require safety and reliability. During the long-term service of the spacecraft structure, the bolts are prone to loosening. Electromechanical impedance (EMI) method is sensitive to bolt loosening. This paper developed a small integrated, low-power EMI monitoring device for CubeSat to detect bolt loosening, since CubeSat is low cost and has a long-time service in the orbit. The monitoring device is a two-layer structure of 0.6U. The upper layer is the experimental specimen layer. The other layer is the impedance measurement layer which can measure and transfer the impedance and temperature information. This layer consists of impedance measurement module, channel selection module, microprocessor module, communication module and power management module. The impedance results obtained by the monitoring device matched well with these by impedance analyzer. Besides, the influence of temperature on impedance measurement was studied, and two methods of compensating impedance curves were compared. Finally, the bolt loosening experiment was performed on one bolted beam of the specimen at different temperatures. The results show that, combined with the temperature compensation of the real part curve of the impedance, the bolt loosening can be clearly distinguished from the healthy condition. This monitoring device and temperature compensation method are expected to be applied on the CubeSat.
Direct Pressure Measurement and Flow Visualization of Cavitation in a Converging-Diverging Nozzle
Authors: Gallman Benjamin , Beck B. Terry , Hosni Mohammad H.
Published: January 2020

While normally certain unwanted phenomena are to be avoided, cavitation has useful engineering applications. Specifically, it can be used as to create cooling potential in a novel non-vapor compression refrigeration process. Cavitation occurs when the pressure of the working fluid (compressed liquid) drops below the saturation pressure. Since the cavitation (flash) results in an abrupt reduction in temperature, the working fluid can take in energy as heat from the surroundings during cavitation, which results in a cooling potential (refrigeration). In a converging-diverging nozzle, as the fluid passes through the throat the pressure decreases. If the pressure drops below the saturation pressure, cavitation can occur. The current research focuses on measuring the pressure nearby the cavitation front, and the associated pressure distribution within the two-phase region, in a converging diverging nozzle. A blow-down flow system was used to conduct measurements with water as the working fluid. The flow rate was measured with a rotameter and a Coriolis flow meter. The nozzle is a transparent 3D printed nozzle with an inlet diameter of 9.3 mm, throat diameter of 1.71 mm, and an outlet diameter of 9.3 mm. The upstream reservoir was kept at atmospheric pressure and was elevated above the level of the nozzle inlet. The downstream reservoir was evacuated to create a pressure difference that would drive fluid through the nozzle. The pressure distribution within the nozzle was measured using eight pressure transducers connected to the nozzle with 0.006” diameter taps, and a high-speed camera was used to capture flow visualization. The pressure distribution was measured for steady cavitating flow at several back pressures, and during an increasing flow rate to capture pressure changes during cavitation initiation. These results give direct pressure measurements during cavitating flow, along with the accompanying flow visualization. They should prove useful for furthering the understanding of the metastable fluid mechanics behavior of cavitating flows, and thereby contribute to the ability to ultimately maximize the cooling potential of the cavitation phenomena.
A Detachable Thermoelectric Generator As a Power Source for a 3G Camera Network Using a Steam Pipe As a Heat Source
Authors: Dell Robert , Petralia Michael Thomas , Pokharel Ashish , Gislason Gudmundur , Unnthorsson Runar
Published: January 2020

The author’s patented thermoelectric generator system uses a steam pipe as a heat source and ambient cooling in an exterior location at the Agricultural University of Iceland. This produces up to 7.2 watts (W) steady state using 6 thermoelectric modules.

The system has been powering a 3G webcam system since 2017 while it’s surplus power trickle charges 12 volt (V) batteries. New low power monitoring options originally developed for photovoltaic systems can be easily retrofitted for improved efficiency, additional and control options. The test results confirm the viability of a thermoelectric generator as power sources for security systems.
Modelling Stress Softening and Necking Phenomena in Double Network Hydrogels
Authors: Morovati Vahid , Saadat Mohammad Ali , Dargazany Roozbeh
Published: January 2020

Double network (DN) gels are three-dimensional polymer matrices formed by interpenetrating networks. In contrast to the conventional single-network gels, DN gels have significant toughness, which makes them a promising material for different biomedical and biological applications. However, DN gels show complicated inelastic behavior including the Mullins effect and necking instability. Despite extensive efforts on modelling different aspects of the damage process in gels, the micro-mechanical modelling of the mechanisms that lead to necking in DN gels remains to be a challenging task. Here, a constitutive model is proposed to understand and describe the mechanical behavior of DN gels based on statistical micro-mechanics of interpenetrating polymer networks. DN gels behavior is divided into three parts including pre-necking, necking, and hardening. The first network is dominant in the response of the gel in the pre-necking stage. The breakage of the first network to smaller network fractions (clusters) induces the stress softening observed in this stage. The interaction of both networks and the second network are also considered as main contributors to the response of gel in necking and hardening stages, respectively. The contribution of clusters decreases during the necking as the second network starts hardening. The numerical results of the proposed model are validated and compared by uni-axial cyclic tensile experimental data of DN gels.
Vibration Analysis of a Horizontal Partially Fluid-Filled Cylindrical Shell Considering Sloshing Effect of Free Surface
Authors: Pan Luyan , Zhu Xiang , Li Tianyun , Han Yueyang , Liang Xiaotian
Published: January 2020

The free and forced vibrations of a horizontal partially fluid-filled cylindrical shell with sloshing effect are studied based on the finite element method. The structure and inner fluid taking into account the sloshing effect of the free surface are simulated by the shell and acoustic elements respectively. The natural frequencies of sloshing fluid and shell structure are calculated simultaneously by the FEM. To verify the accuracy of the results, the shell’s natural frequencies are compared with published results. The effects of the structural parameters and fluid depth on the vibration of the coupled system are discussed. The natural frequencies of a sloshing fluid can be divided into low-frequency and high-frequency part, and the low-frequency part refers to the pressure fluctuation caused by the sloshing of the free surface, while the high-frequency part corresponds to the pressure fluctuation of the particles below the free surface. The thinner the shell thickness is, the lower the sloshing frequency of free surface and coupled modal frequency of the shell are. With the increase of the liquid depth, the natural sloshing frequency of the free surface increases slightly while the coupled modal frequency of the shell decreases. The impact of the free surface effect on the coupled vibration cannot be omitted when the shell’s natural frequencies are close to the sloshing frequencies.
Model-Based Resilience Assessment Framework for Autonomous Systems
Authors: Diaconeasa Mihai A. , Mosleh Ali , Morozov Andrey , Tai Ann T.
Published: January 2020

While automation technologies advance faster than ever, gaps of resilience capabilities between autonomous and human-operated systems have not yet been identified and addressed appropriately. To date, there exists no generic framework for resilience assessment that is applicable to a broad spectrum of domains or able to take into account the impacts on mission-scenario-level resilience from system-specific attributes. In the proposed framework, resilience is meant to describe the ability of a system, in an open range of adverse scenarios, to maintain normal operating conditions or to recover from degraded or failed states in order to provide anticipated functions or services to achieve mission success. The term resilience is introduced in relation with classical terms such as fault, error, failure, fault-tolerance, reliability, and risk. The proposed model-based resilience assessment framework is based on a resilience ontology that enables the use of system models into reliability and risk models for transparent, persistent, and up-to-date modeling and quantification. A SysML profile and associated OWL ontology are defined to enable the use of a range of resilience mechanisms into the design and operation of a system.
How to Establish Digital Thread Using 3D Factory
Authors: Ajay Holey , Shashank Alandikar
Published: January 2020

In a manufacturing assembly line scenario, factory layout is one of the most crucial information used by manufacturing, facility and factory automation engineers for planning purposes. It is important for manufacturing, facility and operations team to work with most up-to-date layout when product, process and operational information on the shop-floor is constantly changing. There are four elements which governs availability of a real-time layout, these are nothing but Product Design, Manufacturing Process Planning, Layout Planning and Shop-floor. The layout must accommodate these changes coming from product design, process updates and shop-floor modifications on real-time basis so that there is no confusion amongst the stakeholders while referring layout data for their planning purpose. If we talk about the impact on the layout because of product design and process design, it is hardly managed real-time due to the isolated systems to manage these data. The integration of product, process and plant (PPP) is becoming crucial to facilitate collaboration and shrink new product introduction lead time where as real-time update from the shop-floor changes is expected in the era of digital transformation. One of the reasons why the integration of product, process and plant (PPP) does not happen is multiple isolated systems used to maintain this data, there are also challenges to feed data back from the shop-floor because of the non-availability of the thread between these objects.

The paper is about how factory layout can be developed integrating product, process and plant (PPP) in a single dynamic environment and establish a digital thread between the product design, manufacturing process planning and factory layout to trigger real-time changes and facilitate digital twin of the factory. The methodology adopted here is to develop bill of material for manufacturing resources and align it with the product data management. This approach not only provides ability to maintain change control over resource objects but also helps in configuration management of the resource bill of material. The resources are grouped together as layout structure for the plant with each object required to manufacture the product. The detailed layout developed for the plant while integrating with product and process is used to establish connection with objects on the shop-floor through sensors and IOT (Internet of Things) devices to form digital twin. Such details added in layout which is So far there are no efforts to digitalize every information on the factory floor and able to generate Digital Twin of the factory by connecting physical objects with the digital objects. Paper will elaborate the approach to establish digital thread between PPP and how this can become foundation to drive digital twin of the factory.