bluuebunny/crossref_metadata_2025 huggingface dataset:
Acoustic Emission Low-Temperature Performance Grade Evaluation of Asphalt Roadways Materials
Authors: Sun Lihui , Buttlar William G. , Behnia Behzad , Reis Henrique
Published: January 2019

Low-temperature cracking is a major form of distress in asphalt concrete pavements located in cold regions. A review of the background and fundamental aspects of the Acoustic Emission (AE) based approach with a brief overview of its application to estimate low-temperature performance of unaged, short-term, and long-term aged binders as well as asphalt concrete materials are presented. A comparison of the cracking temperatures estimated using the traditional rheological-based method and the embrittlement temperatures obtained using the proposed AE-based method is presented and discussed. In addition, embrittlement temperatures of asphalt concrete samples extracted from field cores are also presented and discussed. Results indicate that the AE-based method is faster and more accurate than the traditionally used methods. Moreover, results suggest that AE could be considered as a viable rapid, inexpensive, yet precise characterization approach for pavement materials, which could be effectively used towards enhancing pavement sustainability and resiliency.
Effect of Preform During Low Pressure Tube Hydroforming
Authors: Trott Ashley , Nikhare Chetan P.
Published: January 2019

Tube hydroforming is one of the manufacturing processes to produce lightweight components for automotive and aerospace industries. In this process a fluid medium is used to form a component either with high or low internal pressure. This process has gained popularity due to its many advantages such as part consolidation, quality of the formed part, and the possibility of unique shapes with indents or angles. In low-pressure tube hydroforming, the tube is marginally pressurized to a fixed volume during the closing of the die. Tube hydroforming can produce many geometric options which reduces the need for welding operations. The success of the tube hydroforming process is contingent on the ideal combination of material properties, process limitations, process sequence, and die geometry. The focus of this paper is to investigate the effect of preform on the low-pressure tube hydroforming in terms of pressure requirement, buckling and die filling. For this, a plain strain 2D model was created and hydroforming process was simulated. The tube was preformed to various widths and then hydroformed using low pressure. Two pressure conditions were simulated. The thickening of tube was observed which resulted in buckling of the tube. With higher pressure the buckling reduced but thickening of tube increased.
Study of Spurious Wave Reflection at the Interface of Peridynamics and Finite Element Regions
Authors: Kulkarni Shank S. , Tabarraei Alireza , Wang Xiaonan
Published: January 2019

Peridynamics ability to model crack as a material response removes deficiencies associated with using classical continuum-based methods in modeling discontinuities. Due to its nonlocal formulation, however, peridynamics is computationally more expensive than the classical continuum-based numerical methods such as finite element method. To reduce the computational cost, peridynamics can be coupled with finite element method. In this method, peridynamics is used only in critical areas such as the vicinity of crack tip and finite element method is used everywhere else. The main issue associated with such coupling methods is the spurious wave reflections occurring at the interface of peridynamics and finite elements. High frequency waves traveling from peridynamics to finite element spuriously reflect back at the interface and the amplitude of transmitted waves also alter. In this paper, we take an analytical approach to study this phenomenon of spurious reflections. We study the impact of factors such as horizon size of peridynamic formulation, discretization, and change in mesh size on the amplitude of spuriously reflected waves. Finally, we present a method to reduce these spurious reflections by using Arlequin method.
Photo-Acoustic Based Non-Contact and Non-Destructive Evaluation for Detection of Damage Precursors in Composites
Authors: Wang Siqi , Xiang Liangzhong , Liu Yingtao , Liu Hong
Published: January 2019

Damage precursor in composites can lead to large structural damages, such as delamination, in carbon fiber reinforced plastic (CFRP) composites due to complex load conditions and environmental effects. In addition, multiple types of damage precursors including micro-scale matrix cracks, fiber pull-out from matrix, and fiber breakages, are extremely difficult to detect due to the limitation of resolution of current non-destructive evaluation (NDE) technologies.

This paper presents a photo-acoustic based non-contact NDE system for the detection of damage precursors with extremely high resolution up to one hundred micrometers. This system consists of three major components: picoseconds pulsed laser based ultrasonic actuator, ultrasound receiver, and data processing and computing subsystem. Picoseconds pulsed laser is used to generate ultrasonic propagations in composites during the NDE process, and the ultrasound signals are recorded by the ultrasound receiver. Three-dimensional microstructure of the individual composites grid within the composite is able to be reconstructed for further analysis. The size and position of the damage precursors are evaluated with high accuracy up to 100 μm. The experimental results demonstrate that this imaging system is able to provide a novel non-contact approach with extremely high resolution for damage detection of CFRP composites. In addition, the developed NDE system has a wide industrial application in aerospace, automobile, civil, mechanical, and other key industries.
Efficient Feedrate Optimization Method for Spline Toolpath With Curvature-Base Planning and Accurate Interpolating
Authors: Zhang Yong , Zhao Mingyong , Ye Peiqing , Jiang Jiali , Zhang Hui
Published: January 2019

The well-designed feedrate optimization algorithm can obtain higher machining efficiency with various machining related constraints, thus, it is widely considered in the high-speed and high-precision machining. However, the low computational efficiency still limits the application of the optimization method. For the non-linear optimization problem of spline toolpath with feedrate-, actuator velocity-, acceleration- and jerk-limited, a linear approximation is adopted by a pseudo-jerk method and the efficient linear programming method can be applied to solve the optimization problem. To improve computational efficiency further, curvature-base window technique is presented and the whole spline toolpath is split at the curvature extreme points, which are also named critical points in traditional planning method. Thereafter, a novel feedback interpolation is presented based on Steffensen iterative accelerator method to eliminate the feedrate fluctuation caused by nonanalytic relationship of spline parameter and arc-length. Finally, simulations and experiments validations show that the proposed method is able to reduce computational burden and traversal time notably with multi-constraints.
Experimental Study of Convective Heat Transfer in Standard and Cross-Drilled Brake Discs With Radial Vane and X-Lattice Cores
Authors: Yan Hongbin , Feng Shangsheng , Wu Wei-Tao , Lu Tian Jian , Xie Gongnan
Published: January 2019

To improve the cooling performance of disc brake systems, cross-drilled holes penetrating across the rubbing discs are separately introduced into a commercial radial vane brake disc (as reference) and a novel X-lattice cored brake disc. Prototype samples of both the reference and cross-drilled brake discs are fabricated. A rotating test rig is designed and constructed to characterize and compare the cooling performance of the brake discs with infrared thermography. Within the typical operating range of a vehicle, e.g., 200–1000 rpm, the experimental results show that the introduction of cross-drilled holes can substantially enhance brake disc cooling. For the radial vane brake disc, the overall Nusselt number is enhanced by 31%–44%; for the X-lattice cored brake disc, the cross-drilled holes only lead to 9%–18% enhancement. As the radial vane brake disc and the X-lattice cored brake disc with cross-drilled holes exhibit similar cooling performance, flow through the cross-drilled holes has a more prominent effect on the former than the latter. Corresponding fluid flow and heat transfer mechanisms underlying the enhanced heat transfer by cross-drilled holes and the different effects of cross-drilled holes on the two distinct brake discs are explored. The experimental comparison and the thermo-fluidic physics presented in this paper are beneficial for engineers to further improve disc brake cooling.
Thermoeconomic Analysis of a Solar MVC Desalination System
Authors: Gao Lei , Hwang Yunho , Kim Gyeong Sung
Published: January 2019

Globally, about 10% of the world population does not have access to enough fresh water. In many hot-and-dry coastal regions and islands, the desalination of seawater might be the only practical option to have a fresh water supply. Therefore, low-cost desalination system is critical for freshwater demands. To address this issue, a desalination system consisting of solar photovoltaic (PV) and mechanical vapor compression subsystem is proposed in this study. The entire desalination system was modeled and designed to produce 10,000 m3 of fresh water per day at the coast of San Francisco, California. Key components such as water vapor compressor, solar PV panel, and three-stream heat recovery unit were designed, and their performances were analyzed. The effects of design variables and operating conditions on the system performance were investigated through a parametric study. Finally, an economic analysis was conducted and compared with current desalination technologies. The analysis results show that the specific power consumption of desalination system can reach 14.4 kWh/m3 when the evaporation temperature is 70°C. It is found that the evaporating temperature has a great influence on the heat pump system efficiency and evaporator design. The levelized cost of the proposed system is $0.76 per m3 of fresh water which is lower than current grid-powered vapor compression desalination system and other thermal desalination systems. The proposed solar PV driven desalination improves thermoeconomics of desalination system by applying low-lift operating condition to the vapor compression cycle so that it can contribute to solving the fresh water supply challenges.
A Mathematical Functional Decomposition Approach Through Granularity Partition Process in Quotient Space
Authors: Li Y. T. , Wang Y. X.
Published: January 2019

Over the past decades, several methodologies have coalesced around the functional decomposition and partial solution manipulation techniques. These methodologies take designers through steps that help decompose a design problem and build conceptual solutions based on the intended, product functionality. However, this kind of subjective decomposition restricts solutions of conceptual design within designers’ intended the local, rather the whole, solution space. In such cases, the ability for AI-based functional reasoning systems to obtain creative conceptual design solutions is weakened. In this paper, a functional decomposition model based on the domain decomposition theory in quotient space is proposed for carrying out functional decomposition without needing functional reasoning knowledge to support. In this model, the functional decomposition is treated as a granularity partition process in quotient space composed of three variables: the domain granularities, the attribute properties, and the topological structures. The closeness degrees and the attribute properties in fuzzy mathematics are utilized to describe the fuzzy equivalence relations between the granularities in the up-layer and in the lower-layer of the functional hierarchies. According to the order characteristics in the partially sequential quotient space, based on the homomorphism principle, the attribute properties and the topological structures corresponding to the lower-layer of the functional hierarchies are constructed then. Here, the attribute properties are expressed with membership functions pointed to the lower-layer from the up-layer of the functional hierarchies, and the topological structures are expressed with matrixes and the directed function network represent the topological connections among the subfunctions in the lower-layer of the functional hierarchies. Through refining the functional decomposition process step by step, and traversing all tree branches and leaf nodes in the functional decomposition tree, the functional hierarchies are obtained. Since the functional decomposition process not need the user to indicate or manage desired functionality, the model presented in this paper can reduce designers’ prejudices or preconceptions on the functional hierarchies, as well as extend the solution space of conceptual design.
Characterizing Microfluidic Operations Underlying an Electrowetting Heat Pipe on the International Space Station
Authors: Wikramanayake Enakshi , Hale Renee , Elam John , Shahriari Arjang , Bahadur Vaibhav , Alvarez-Hernandez Angel R. , Howard Nathan
Published: January 2019

Electrowetting heat pipes (EHPs) are a newly conceptualized class of heat pipes, wherein the adiabatic wick section is replaced by electrowetting-based pumping of the condensate (as droplets) to the evaporator. Specific advantages include the ability to transport high heat loads over long distances, low thermal resistance and power consumption, and the absence of moving mechanical parts. In this work, we describe characterization of key microfluidic operations (droplet motion and splitting) underlying the EHP on the International Space Station (ISS). A rapid manufacturing method was used to fabricate the electrowetting device on a printed circuit board. Key device-related considerations were to ensure reliability and package the experimental hardware within a confined space. Onboard the ISS, experiments were conducted to study electrowetting-based droplet motion and droplet splitting, by imaging droplet manipulation operations via pre-programmed electrical actuation sequences. An applied electric field of 36 Volts/um resulted in droplet speeds approaching 10 mm/s. Droplet splitting dynamics was observed and the time required to split droplets was quantified. Droplet motion data was analyzed to estimate the contact line friction coefficient. Overall, this demonstration is the first-ever electrowetting experiment in space. The obtained results are useful for future design of the EHP and other electrowetting-based systems for microgravity applications. The testing was performed under the Advanced Passive Thermal eXperiment (APTx) project, a project to test a suite of passive thermal control devices funded by the ISS Technology Demonstration Office at NASA JSC.
Investigation of Process Parameters on Dry Sliding Wear of Self-Lubricating Metal Matrix Composites
Authors: Velukkudi Santhanam Senthil Kumar , Manickam Dhanashekar , Sivagnanam Karthikeyan
Published: January 2019

In recent years, conventional materials are rapidly replaced by advanced aluminium composites due to its lighter in weight and high-performance characteristics. These materials find vast applications in automotive components because of its excellent combination of properties such as high specific strength, high specific stiffness, better dimensional stability and enhanced wear characteristics. The present work is focused on hybrid composites manufactured by stir casting route where the A356 alloy is the matrix and SiC + Moringa Oleifera Ash (MOA) particles as reinforcements. The influence of Moringa Oleifera Ash (MOA) particles (self-lubricant) on the wear behaviour of the composites is studied. Fabricated composites are tested on a pin-on-disc test rig at dry sliding wear conditions to study the influencing input parameters such as load, sliding distance and composites. A356 Aluminium alloy is reinforced with 5% SiC as primary reinforcement, varying MOA particles with 1% and 3% as secondary reinforcement. The design of experiments (DOE) approach using Taguchi method was adopted to perform the experiments according to L9 orthogonal array and analyse the results. From Taguchi analysis, combination of best suited values is identified and reported. Inquest of influential wear test parameters and its effect on wear and friction is determined using the signal-to-noise ratio and analysis of variance (ANOVA).
Fruit Ripeness Estimation for Avocado Using Thermal Imaging
Authors: Gurupatham Sathish K. , Ilksoy Erhan , Jacob Nick , Van Der Horn Kevin , Fahad Fahad
Published: January 2019

Novel technologies have always been an indispensable part of the scientific enterprise and a catalyst for new discoveries. The invisible radiation patterns of objects are converted into visible images called thermograms or thermal images. Thermal images can be utilized to estimate the ripeness of some fruits which do not change their color from yellow to green when they are ripe. Thermal imaging techniques are very helpful since color and fluorescent analytical approaches cannot be applied to these fruits. In this work, it is shown that different ripeness levels of avocado (Hall type) using a non-destructive method called thermal imaging, in two dimensional spaces. The work is based on the fact that fruits have different specific heat capacities at different temperatures, thus making their thermal images clear indicators of ripeness.
A Life Cycle Assessment of Biofuel Produced From Waste Cooking Oil
Authors: Spencer Sierra , Scott Malia , Macken Nelson
Published: January 2019

Biofuels have received considerable attention as a more sustainable solution for heating applications. Used vegetable oil, normally considered a waste product, has been suggested as a possible candidate. Herein we perform a life cycle assessment to determine the environmental impact of using waste vegetable oil as a fuel. We present a cradle to fuel model that includes the following unit processes: soybean farming, soy oil refining, the cooking process, cleaning/drying waste oil, preheating the oil in a centralized heating facility and transportation when required. For soybean farming, national historical data for yields, energy required for machinery, fertilizers (nitrogen, phosphorous and potassium), herbicides, pesticides and nitrous oxide production are considered. In soy oil refining, steam production using natural gas and electricity for machinery are considered inputs. Preprocessing, extraction using hexane and post processing are considered. In order to determine a mass balance for the cooking operation, oil carryout and waste oil removal are estimated. During waste oil processing, oil is filtered and water removed. Data from GREET is used to compute global warming potential (GWP) and energy consumption in terms of cumulative energy demand (CED). Mass allocation is applied to the soy meal produced in refining and oil utilized for cooking. Results are discussed with emphasis on improving sustainability. A comparison is made to traditional fuels, e.g., commercial fuel oil and natural gas. The production of WVO as fuel has significantly less global warming potential but higher cumulative energy consumption than traditional fuels. The study should provide useful information on the sustainability of using waste cooking oil as a fuel for heating.
The Effect of Delta Winglet Inclination Angle on the Vortical Flow Downstream
Authors: Wang Junguo , Ting David S.-K. , Ray Steve
Published: January 2019

The effect of the inclination angle of a delta winglet vortex generator with a length-to-height (c/h) ratio of 2, at 30 degrees with respect to an Reh = 9000 wind, on the resulting flow along a flat plate is quantified in a wind tunnel. The vortical flow characteristics at 13h downstream of the leading edge of the delta winglet are detailed with the help of a triple-hot-wire probe. Specifically, the local velocity, vortex shape, size and strength, turbulence intensity, integral length and Taylor microscale are deduced. The results show that the into-the-plate velocity in the inflow region increases, while the out-of-the-plate velocity in the outflow area decreases, with inclination angle. The 90-degree inclination angle appears to furnish higher values of turbulent intensity, integral length and Taylor microscale.
Pressure Fluctuation Mitigation in a Francis Turbine With Water Injection: Computational Study
Authors: Altimemy Muhannad , Daskiran Cosan , Attiya Bashar , Liu I-Han , Oztekin Alparslan
Published: January 2019

Computational fluid dynamics simulations were performed on Francis turbine using Reynolds-averaged Navier-Stokes (RANS) with k-ω SST turbulence model. Simulations were conducted at the turbine’s best efficiency point with a Reynolds number of 2.01 × 107. Water injection was admitted from the runner cone in the stream-wise direction. The aim of this process was to investigate the influence of water injection on the turbine performance and the pressure pulsation. The water injection did not affect the nominal value of the turbine’s power generation. Straight vortex rope was observed at the centerline of the draft tube. Moreover, helix-shaped vortex ropes were obtained near the draft tube surface. The water injection expands the central vortex rope, but it did not suppress or disrupt the helix-shaped peripheral vortex rope near the draft tube surface. The pressure fluctuation became less regular after the water injection, but the fluctuation level remained similar.
Sawing Status Prediction of Diamond Sawblade Sawing Concrete Based on the Characteristics of Material Composition
Authors: Hu Shanshan , Yang Fan , Yang Zili , Xiong Feixiang , Shi Weiwei , Tang Hongqun
Published: January 2019

Diamond sawblade is an efficient tool to building renovation or demolition. Concrete used in construction is a typical composite material with random distribution, which is difficult to accurately identify and predict even under the same processing conditions, and tool life of diamond sawblade is difficult to control.

In this paper, by cutting out single component of the hard and soft aggregate separately from concrete, the single component and concrete experiments were carried out to understand the sawing characteristics of different components. The wavelet decomposition was used to analyze the characteristic of each frequency band of the different components sawing force and vibration signals, and the sensitive frequency bands after correlation coefficient and energy ratio variation of each wavelet layer were extracted to judge the bluntness status of sawblade. By taking the Root-Mean-Square (RMS) value, the energy ratio of d2 and d5 wavelet layers and the standard deviation of sawing force and vibration signal as the characteristic values of the sawblade, a neural network optimized by bat algorithm was established to analyze the concrete processing signals and predict the working state of the sawblade. Evidence theory was adopted to combine the prediction results of sawing force and vibration samples to increase the overall prediction accuracy and reliability. The test sample showed that this method can correct inconsistent individual sensor predictions while being as close to the actual status value as possible. It provides an effective tool life prediction way of the diamond sawblade and a theoretical method for the monitoring of non-metallic materials with inhomogeneous components.
A New Approach for Locating the Instantaneous Centers of Zero Velocity for 1-DOF Planar Linkages
Authors: Diab Nadim
Published: January 2019

This paper presents a new graphical technique to locate the secondary instantaneous centers of zero velocity (ICs) for one-degree-of-freedom (1-DOF) kinematically indeterminate planar mechanisms. The proposed approach is based on transforming the 1-DOF mechanism into a 2-DOF counterpart by converting any ground-pivoted ternary link into two ground-pivoted binary links. Fixing each of these two new binary links, one at a time, results in two different 1-DOF mechanisms where the intersection of the loci of their instantaneous centers will determine the location of the desired instantaneous center for the original 1-DOF mechanism. This single and consistent approach proved to be successful in locating the ICs of various mechanisms reported in the literature that required different techniques to reach the same results obtained herein.
Dealing With Student Profile Diversity in an Industrial Engineering and Management Program: PBL vs “Non-PBL”
Authors: Alves Anabela C. , Moreira Francisco , Leão Celina P.
Published: January 2019

The Integrated Master in Industrial Engineering and Management (IEM) program has been implementing Project-Based Learning (PBL) for more than 15 years in the first year, first semester. The IEM program is currently attracting students from different programs, using transfer mechanisms, who normally already have passed some of the courses on their original program. Additionally, this program also attracts a number of students already working in some companies. These students are a bit older and their profile is also distinct from that of their fellow colleagues, which enter the university using a regular national ingress process. Thus, distinct situations are identified that demand a different learning approach. The teachers have come-up with one such distinct approach and called it “non-PBL”, since the PBL model is structured in a way that students must have a specific profile, namely, to be first-year IEM student and enrolled a similar set of curricular units. With this in mind, this paper presents these situations, and describes the solution found to address this diversity. The solution must promote similar competences on both PBL and “non-PBL” students. A heavier workload is imposed on the teachers, given that the number of “non-PBL” teams formed can be as much as the number of PBL teams. Nevertheless, the results demonstrate that the “non-PBL” students successfully conclude the first year and that they value the solution proposed, in spite of the difficulties raised with this process.
Design and Analysis of Electrostatically Actuated Mechanical Sensor for Graphene
Authors: Tekes Ayse , Park Jungkyu
Published: January 2019

Very little is known about the fracture behaviors of novel nanomaterials such as carbon nanotubes and graphene due to the difficulty of sample manipulation and in situ detection of their failure mechanism. In the present study, the design and analysis of a Microelectromechanical System (MEMs) device is presented for the tensile testing of single layer graphene. The electrostatically actuated dual parallel plate actuators in the proposed MEMS device enable in situ measurement in a scanning electron microscope by stretching the two ends of a nanostructured sample simultaneously. The elongation in the specimen is obtained by nonlinear finite element analysis using COMSOL, and MATLAB. For the validation of the proposed MEMS device, a lumped model of the system is utilized to analyze the stress-strain behavior of the nanostructured sample under the force generated by the electrodes.
Development of a Multidisciplinary Engineering Research Program for Middle/High School Teachers
Authors: Li Wen , Kim Joshua , Kim Drew , Alster Adam , Livezey Marianne , Duddles Tuyen
Published: January 2019

Science, technology, engineering, and mathematics (STEM) education in K-12 schools is critical to inspire young students and prepare them for future college coursework and careers in science and engineering. An effective mechanism for creating and sustaining successful STEM education is to train well-qualified K-12 teachers with a positive attitude and deep knowledge skills in STEM fields. Supported by the National Science Foundation’s Research Experience for Teachers program (NSF RET), the RET Site at Michigan State University (MSU) aims to build a multidisciplinary engineering research program for middle and high school teachers and their students, within a coherent theme of “Smart Sensors and Sensing Systems”. This paper presents an introduction to the MSU’s Site program and highlights the learning outcomes and achievements of the RET participants. The MSU Site has four main components including authentic research experience for teachers during an intensive summer program; curriculum development by integrating engineering design units into teachers’ courses; professional skill development through seminars, facility tours, and field trips; and finally classroom implementation of the developed curricula. Throughout the 6-week summer program, teacher participants were given the opportunity to work closely with graduate students and engineering professors on current research projects in university laboratories. The teachers’ research activities culminated with a final poster report and oral presentation during a symposium at the end of the summer program. Follow-up classroom visits helped to build a strong connection between local middle/high schools and MSU to smooth students’ transitions to college. Since 2016, the Site has graduated 21 middle and high school teachers from the greater Lansing-Detroit area that serve large populations of minority and female students. These RET teachers have produced over 24 sets of curriculum plans and classroom activities, 3 sets of which have been published by an online digital library, TeachEngineering.org (TE), and 8 sets of which have been accepted by TE. Finally, from the findings of the RET Site, the paper discusses best practices and recommendations for incorporating teachers into a university laboratory setting.
Preliminary Design of a Lab-Scale Organic Rankine Cycle for Waste Heat Recovery Applications
Authors: Cabezas Carlos , Mendoza José , Ponce Iván , Cantorin Rafael , Gonzales Daniel , Estrella Jessica , Peralta Sergio , Celis Cesar
Published: January 2019

This work describes the preliminary design of a lab-scale organic Rankine cycle (ORC) for waste heat recovery based applications. As heat source for the ORC, exhaust gases from an actual internal combustion engine are utilized. The design is primarily carried out accounting for the working fluid path. More specifically, a brief introduction to be subject is initially provided. The details of the ORC preliminary design are discussed next. This includes the selection of the main working fluid, the definition of the ORC plant layout and the design of the main ORC plant components. The specifics of an overall control loop resembling an actual control system that could be used in the designed ORC based plant is also provided. In terms of power output, the results show that up to 1.68 kW can be produced from the waste heat of internal combustion engines like the one accounted for in this work. Compared to the shaft power (25.1 kW) associated with the internal combustion engine providing the heat source, this power output represents about 7%. The preliminary design described here constitutes the first step of a large effort aiming to build, install and test a lab-scale ORC for educational purposes. It is expected that such ORC based plant allows carrying out in future several studies, including the development of different control strategies for maximizing the operational performance of these plants.
Minimizing Pain in Below Knee Amputees’ Patients Wearing Prosthetic Socket by Increasing Flexibility in Specific Relief Areas
Authors: Nehme Gabi , Khalife Yousef , Chagoury Antoun , Dib Nehme Micheline
Published: January 2019

Background: Pressure distribution for transtibial amputees (TTA) patients varies at the limb socket interface according to several factors. Although socket technology is getting more advanced, the majority of researchers are still facing problems with relief areas.

Objectives: This study focused on the theoretical and experimental aspects of the design to figure out patients’ sensitivity to pain when wearing sockets. Relief areas were analyzed using data collected from patients’ centers and optimized under different static and dynamic conditions.

Methods: Finite element trials and DOE optimization using Design Expert 8 software and analysis of variance (ANOVA) revealed that holes with relief areas are appropriates for lower extremities patients where scanning electron images (SEM) of the worn areas show direct relations between relieved sockets with holes at fibula head (FH) and patient lifestyle and activity.

Clinical Relevance: A patient that moves rather slowly, as a result of old age or sedentary level of activity would greatly benefit from the FH socket hole implementation, and thus reduces the wear of socket materials after longer period of time and increases the level of comfort of patient skins. the interviews conducted were evident that patients endured pain at the PT and FH. Moreover, further studies were performed on the FH, and results revealed that lateral forces play a major role and is influenced by the lifestyle of the patient.
Prediction of Residual Stress and Damage in Thermal Spray Coatings Using Hybrid Computational Approach
Authors: Abubakar Abba A. , Arif Abul Fazal M. , Al-Athel Khaled S. , Akhtar S. Sohail
Published: January 2019

Due to the multilayered pattern of coating deposition, numerical prediction of residual stress and damage in thermal spray coatings (TSCs) has been challenging. Several numerical approaches previously used failed to capture essential aspects such as deposition stress build-up, presence of heterogeneities, and influence of process parameters. In the present study, a hybrid computational approach which combines “point cloud” (PC) and finite elements (FE) has been used to model the spray process as well as the evolution of residual stress and damage. Smooth particle hydrodynamics (SPH) is used to model multiple droplets deposition and associated deformation on PC. Then, several recent algorithms (for point cloud processing) are used to convert the deformed droplets (in form of PC) into FE domains (i.e. splats). The FE mesh of deposited splats is used for thermo-mechanical finite element analysis where the evolution of temperature, residual stress and damage is predicted on simulated coating microstructure. By comparing our numerical results with that of previous works, the hybrid approach has been found to be a viable tool for quantitative assessment of residual stresses and failure in TSCs.
Detection of Misfire in a Six-Cylinder Diesel Engine Using Acoustic Emission Signals
Authors: Jafari Mohammad , Borghesani Pietro , Verma Puneet , Eslaminejad Ashkan , Ristovski Zoran , Brown Richard
Published: January 2019

This study will focus on the detection of misfire using Acoustic emission sensor in a multi-cylinder diesel engine. Detection of misfire is important since this malfunction can cause the engine to stall in a short time. In order to investigate the misfire, an experimental engine was run with and without injection of the fuel in the first cylinder. The acoustic emission signal was acquired synchronously with the crank angle signal, in order to have a reference for the transformation from time to angular domain. The AE signal was then processed using the squared envelope spectrum to highlight angle-periodic modulations in the signal’s power (cyclic bursts). This study will present the effectiveness of this combination of sensor technology and signal processing to detect misfire in a six-cylinder diesel engine connected to a hydraulic dynamometer.
Computational Homogenization in Peristatics of Periodic Structure Composites
Authors: Buryachenko Valeriy A.
Published: January 2019

A composite material (CM) of periodic structure with the peristatic properties of constituents (see Silling, J. Mech. Phys. Solids 2000; 48:175–209) is analyzed by a generalization of the classical locally elastic computational homogenization to its peristatic counterpart. One introduces new volumetric periodic boundary conditions (PBC) at the interaction boundary of a representative unit cell (UC). A generalization of the Hill’s equality to peristatic composites is proved. The general results establishing the links between the effective moduli and the corresponding mechanical influence functions are obtained. The discretization of the equilibrium equation acts as a macro-to-micro transition of the deformation-driven type, where the overall deformation is controlled. Determination of the microstructural displacements allows one to estimate the peristatic traction at the geometrical UC’s boundary which is exploited for estimation of the macroscopic stresses and the effective moduli. One demonstrates computationally, through one-dimensional examples, the approach proposed.
An Empirically Determined Design Guideline for Rectangular Cross Section Nitinol Flexure Hinges With the Focus on Flexibility-Strength Trade-Off
Authors: Coemert S. , Olmeda M. , Fuckner J. , Rehekampff C. , Brecht S. V. , Lueth T. C.
Published: January 2019

In our group, we are developing flexure hinge based manipulators made of nitinol for minimally invasive surgery. On the one hand, sufficient flexibility is required from flexure hinges to be able to cover the surgical workspace. On the other hand, the bending amount of the flexure hinges has to be limited below the yielding point to ensure a safe operation. As a result of these considerations, it has to be questioned how much bending angle a nitinol flexure hinge with given geometric dimensions can provide without being subject to plastic deformation. Due to the nonlinearities resulting from large deflections and the material itself, the applicability of the suggested approaches in the literature regarding compliance modeling of flexure hinges is doubtful. Therefore, a series of experiments was conducted in order to characterize the rectangular cross section nitinol flexure hinges regarding the flexibility-strength trade-off. The nitinol flexure hinge samples were fabricated by wire electrical discharge machining in varying thicknesses while keeping the length constant and in varying lengths while keeping the thickness constant. The samples were loaded and unloaded incrementally until deflections beyond visible plastic deformation occured. Each pose in loaded and unloaded states was recorded by means of a digital microscope. The deflection angles yielding to permanent set values corresponding to 0.1% strain were measured and considered as elastic limit. A quasilinear correlation between maximum elastic deflection angle and length-to-thickness ratio was identified. Based on this correlation, a minimal model was determined to be a limit for a secure design. The proposed guideline was verified by additional measurements with additional samples of random dimensions and finite element analysis.
The Wisdom of Crowds Approach to Influenza-Rate Forecasting
Authors: Morgan Jeffrey J. , Wilson Otto C. , Menon Prahlad G.
Published: January 2019

Influenza is an important public health concern. Influenza leads to the death or hospitalization of thousands of people around the globe every year. However, the flu-season varies every year viz. when it starts, when it peaks, and the severity of the outbreak. Knowing the trajectory of the epidemic outbreak is important for taking appropriate mitigation strategies. Starting with the 2013–2014 flu season, the Influenza Division of the Centers for Disease Control and Prevention (CDC) has held a “Predict the Influenza Season Challenge” to encourage the scientific community to make advances in the field of influenza forecasting. A key observation from these challenges is that a simple average of the submitted forecasts outperformed nearly all of the individual models. Further, ongoing efforts seek ways to assign weights to individual models to create high-performing ensemble models. Given the sheer number of models, as well as variation in methodology followed among teams contributing influenza-risk forecasts, multiple forecasting models can be combined, by capturing human judgment, to outperform a simple average of these same models. This project exploits such a “wisdom of crowds” approach, using public votes acquired with the help of an R/Shiny based web-application platform in order to assign weights to individual forecasting models on a week-over-week basis, in an effort to improve overall ILI risk prediction accuracy. We describe a strategy for improving the accuracy of influenza risk forecast modeling based on a crowd-sourced set of team-specific forecast votes and the results of the 2017–2018 season. Our approach to assigning weights based on crowd-sourced votes on individual models outperformed an average forecasts of the individual models. The crowd was statistically significantly more accurate than the average model and all but one of the individual models.
An Influence of the Numerical Modeling of the Transition Between the Stator and Rotor on the Thermodynamic Condensation Loss in the Low-Pressure Part of a Steam Turbine
Authors: Jun Guk-chol , Mrózek Lukáš
Published: January 2019

Accuracy of numerical simulation of non-equilibrium steam condensation is strongly influenced by a condensation model, i.e. a nucleation rate model and a droplet growth model. Numerical studies of steam condensation in Laval nozzles show that the choice of the condensation model has a significant influence on nucleation rate, position of nucleation zone and consequently steam wetness and the droplet size in the nozzle outlet.

It is necessary to model the transition area between rotating-rotor and stationary part-stator in numerical simulations of steam flow in steam turbines. For this purpose, “Stage” and “Frozen rotor” rotor-stator interface models are widely used.

The aim of the present work has been to analyze how the numerical modeling of the rotor-stator transition area together with the condensation model influences the result of numerical simulation of flow with non-equilibrium steam condensation in the low pressure part of steam turbine of large power output.
Finite Element Educational Program Improves Mechanical Engineering Technology Student Performance in the Finite Element Class
Authors: Ozlek Serdar
Published: January 2019

The purpose of this paper is to develop Graphical User Interfaces (GUI) in MATLAB’s1 Finite Element educational program and describe how MATLAB GUI programs have been used as educational tools to train Engineering Technology students and improve the success of the students in the Finite Element course.

The complexity of FE analysis forces most of the course to focus on the theoretical aspects of generating FEA models, rather than the application of this analysis tool to solve real world problems. New tools are needed to improve the teaching of Finite Element due to the complexity of FE analysis. FEA can be performed by many commercial difficult FEA software with very specific data entry requirements available in the market. Engineering Technology students improve their learning when the coursework is less theoretical, and more application. Hence, a graphical user interface (GUI) application can provide an additional tool to help teach Engineering technology students. The Finite Element Educational Program has been developed to make the course more challenging to increase the interest in the finite element course of the students and overcome the difficulties of complex software.

I have developed a Finite Element Educational Program using a MATLAB GUI for spring, bar, truss and beam elements to improve student learning of difficult engineering concepts, along with gaining essential knowledge of finite element analysis and design content knowledge. For example, the total stiffness matrix and reduced matrix for the given problem are calculated in the designed program, and these calculated values are not available in any commercial FEA software because these programs are not aimed at education. For over five years, The Finite Element Educational Program results show improvement in student knowledge of difficult engineering concepts and has made finite element lessons easier for students to learn and understand.
A Correlation for Maximum Heat Transfer to Cylinders and Spheres in Gas-Fluidized Beds
Authors: Shah Mirza M.
Published: January 2019

A general correlation is presented for predicting maximum heat transfer coefficient for surfaces submerged in gas-fluidized beds. It has been verified with data for horizontal and vertical cylinders and spheres in beds of a wide variety of particles and gases. The gases include air, cryogens, methane, CO2, ammonia, and R-12. The range of parameters includes: heat transfer surface diameter 0.05 to 220 mm, particle diameter 31 to 15000 μm, pressure 0.026 to 0.95 MPa, and temperature 13 to 1028 °C. The 363 data points from 53 sources are predicted with a mean absolute deviation of 16.2 %. Several other correlations were also compared to the same data but had much larger deviations.
Variable Braking Force Using Intelligent Twin Calipers
Authors: Ganesh V. , Subramanian Chidambaram
Published: January 2019

Automobile Braking System is one of the most important sub systems of the vehicle. It is the primary safety system since the stopping of the vehicle is majorly dependent on this system. This system utilises the frictional force between the tire and the road to stop the vehicle. The braking force required by the vehicle is governed by two factors. One of them is the coefficient of friction between the tire and the road surface, the other one is the load on the vehicle. Thus, required braking force to halt the vehicle with the minimum possible stopping distance varies with the load in the vehicle. If the applied braking force is greater than the required brake force, wheel gets locked which results in increased stopping distance. In order to prevent the wheel lock at low load conditions, a variable braking force system is developed. In Motorcycles, the pillion load majorly contributes to the overall weight. Thus, the amount of braking force required to stop with minimum stopping distance also varies drastically with respect to pillion load condition. Hence, the amount of braking force developed between the road surface and the tire is varied in the variable braking force system. In this project, variable brake force system is achieved by varying the effective disc radius. The maximum braking force developed between the ground and the tire is controlled based on the pillion load on the motor cycle, if friction is present between the tire and the ground. Two calipers are mounted on the brake disc of which one is fixed at a constant distance (constant effective disc radius – 67mm) and the other is movable depending on the load on the motorcycle. The movable caliper slides upwards and downwards such that the effective disc radius is varied based on the pillion load. Using a load cell, the load of the vehicle is determined. A microcontroller is programmed to move the caliper with the help of a stepper motor based on the load on the motorcycle. This way, the effective disc radius is varied for various loads on the motorcycle.