bluuebunny/crossref_metadata_2025_split huggingface dataset:
Contact Stress Analysis During Fretting of a Surface Modified Flat-on-Flat With Round Edge
Authors: Dhaka Pankaj , Prakash Raghu V. 
Published: January 2020

Abstract
In the present work, a two-dimensional finite element analysis is carried out to understand the influence of contact geometry and surface treatment on the fretting behavior of a flat with round edge-on-flat plate contact. The fretting pad and plate are modeled using isotropic elastic material properties of Ti-6Al-4V. The mating pair was subjected to a constant normal load followed by a tangential displacement. The effect of contact geometry was studied by independently varying length of the central flat region and radii of corners. Parameters important from the context of fretting viz. contact pressure and normal stress (in tangential direction) were extracted.
The effect of surface treatment was studied by modeling two layers of different elastic modulus and yield strength on the mating surfaces. It is found that addition of intermediate layers of lower elastic modulus and yield strength than the parent material leads to a reduction in both contact pressure and peak tensile stress; the influence was more on the peak tensile stress than contact pressure. Further, the addition of softer and less stiff layers on the pad is noted to be less advantageous than adding it on both pad and substrate or substrate only case. The study suggests that contact geometry should be taken into account while carrying out surface modifications of contact pairs.
Effect of Obesity on Human Squat Exercise
Authors: Caruntu Dumitru I. , Galarza Jose , Vasquez Simon , Ramos Jennifer , Sander Michael 
Published: January 2020

Abstract
This paper deals with the effect of obesity on human squat exercise. The aforementioned clinical condition affects gait (and other daily common activities) in a sense that alterations are made to gait patterns and speed in order to accommodate the patient when participating in physical activities such as walking, making a turn, etc. This work consists of experimental data collected from a subject during moderate squat exercise. Two cases were considered, first, subject with no additional mass, and second, subject with additional mass. The experimental data is collected in the Biomechanics Laboratory at the University of Texas Rio Grande Valley. The squat depth for each trial was kept at a constant height 1 foot from the ground, which corresponds to moderate squat exercise. Phase planes, tools used in nonlinear dynamics, were used to investigate the significant differences between the two cases, no additional weight vs. additional weight. Also, Lyapunov exponents are calculated to assess the stability of the knee joint. There are significant differences in the lateral direction of the centers of mass of both femur and tibia. Moreover the stability of the knee flexion angle decreases with additional mass.
Design and Experimental Study of Radial Piston Pump With Valve Plate Distribution
Authors: Dong Peng , Zhao Shengdun , Wang Yongfei , Zhang Peng , Han Xiaolan , Liu Chen , Meng Dean , Dong Yuanzhe 
Published: January 2020

Abstract
In the field of forging machinery and construction machinery, the hydraulic transmission has become the preferred transmission mode for its high efficiency. The hydraulic pump is the core component of the transmission system as the power component. It is also the main research focus in the field of hydraulic transmission in recent years. According to the axis direction of the piston and the drive shaft, the piston pump can be grouped into radial piston pump and axial piston pump. There are two shafts in the conventional radial piston pumps, which are distribution shaft and drive shaft to complete distribution the pump and transmission work, and the friction between the shoes and the stator is high for its high load and relative sliding speed. In order to reduce the impact of these drawbacks on pump performance, a valve plate is designed to distribute the oil to avoid the stress of the conventional distribution shaft in this paper. The working principle of the radial piston pump is discussed. An electro-hydraulic proportional servo control system was adopted to control the displacement of the pump. The design and manufacturing of the radial piston pump were completed. A test platform is carried out to test the performance and the variable displacement control system of the radial piston pump with a good test result. The radial piston pump has a certain novelty in structure and has practical value.
Soot Mass Estimation From Electrical Capacitance Tomography Imaging for a Diesel Particulate Filter
Authors: Hassan Salah , Anwar Sohel 
Published: January 2020

Abstract
The Electrical capacitance tomography (ECT) method has recently been adapted to obtain tomographic images of the cross section of a diesel particulate filter (DPF). However, a soot mass estimation algorithm is still needed to translate the ECT image pixel data to obtain soot load in the DPF. In this paper, we propose an estimation method to quantify the soot load in a DPF through an inverse algorithm that uses the ECT images commonly generated by a back-projection algorithm. The grayscale pixel data generated from ECT is used in a matrix equation to estimate the permittivity distribution of the cross section of the DPF. Since these permittivity data has direct correlation with the soot mass present inside the DPF, a permittivity to soot mass distribution relationship is established first. A numerical estimation algorithm is then developed to compute the soot mass accounting for the mass distribution across the cross-section of the DPF as well as the dimension of the DPF along the exhaust flow direction. Experimental data has been used to validate the proposed soot estimation algorithm which compared the estimated values with the actual measured soot mass. The estimated soot mass for various soot load amounts were found to correlate reasonably well with the measured soot masses in those cases.
Modeling and Analysis of Noise Barrier Shape Effects on Highway Automobiles Emission Dispersion
Authors: Wang Shaoguang , Wang Xiuling 
Published: January 2020

Abstract
Noise barriers are common configurations along highways. They are originally designed to impede and absorb the noise from vehicles on highways. Recent research has suggested that noise barriers have significant impacts on near-road automobile emissions. Highway noise barriers can make a great difference on the dispersion of air pollutants on and downstream of highway than those with non-barriers features. Certain shaped noise barriers have better performance on reduction noise than others, but the noise barrier shape effects on emission dispersion are still not clear.
In this paper a 3-dimensional computational fluid dynamics (CFD) model has been developed to simulate the shape effects on highway downstream and nearby region emission dispersion. The realizable k-ε turbulence model was adopted to simulate the turbulent flow caused by fast moving vehicles on highway. A non-reaction species transport model was applied to simulate emission dispersion. The model was first used to simulate rectangular shaped noise barriers effect on highway emission dispersion. Results were compared with the data from literature, and good agreements were observed. Further, simulations were conducted to reveal the noise barrier shape as well as various height effects on emission dispersion on highway and nearby regions.
Improving Students’ Learning and Performance Using Mock Tests in Engineering Classes
Authors: Hossan Mohammad Robiul , Islam Nazmul 
Published: January 2020

Abstract
Class performance and classroom environment have a direct impact on students’ learning and long-term retention of key engineering concepts. In addition, class performance is critical for preserving students’ interest and continuous engagement. However, engineering classes are widely rated as boring and monotonous by students due to one-way lectures and lack of application of active learning techniques. In this study, we employed mock tests as an active learning technique to empower students on their own learning through identification of conceptual weakness, reinforcement of understanding and hence, to improve their overall learning and class performance in two different engineering classes at two different universities. Mock tests were conducted on the exam materials before the occurrence of the actual exams. The mock test key with grading rubric was provided to the students. Students were required to grade their mock test based on the rubric. The impact of this technique is evaluated using questionnaires where students were asked to provide their feedback on the enhancement of their understanding of the material, understanding of grading criteria, improvement on their study habits, and identifying conceptual weakness about a topic. The assessment and student feedback shows that the use of the mock test improves the understanding of basic concepts and topics through perspective transformation. It also shows that it improves the average grade of the class, motivates students to study hard, promotes peer discussion, reduces exam related stresses, and strengthens fellowship among students. Thus, mock tests can be used in other disciplines and classes with similar positive effect.
On the Development of a Thermal Comfort Control for Classrooms Conditioned by Split-Type Systems
Authors: Silva Junior Anastacio , Mendes Nathan , Vilain Rogério , Pereira Marcelo , Mendonça Katia Cordeiro 
Published: January 2020

Abstract
Thermal comfort conditions may vary substantially within an air-conditioned room equipped by split-type systems. In this work, the comfort conditions in a classroom were evaluated experimentally based on the PMV index, according to ISO 7730 Standard that defines the thermal satisfaction in occupied environments. The experiment was carried out at three different supply airflows (high, medium and low) and three set-point temperatures (23, 24 and 25°C). The results showed that there is a considerable variation in the air velocity field in the room as well as in the PMV values for three different supply airflows, consequently significant changes of thermal comfort indices can be noticed. Several curves were adjusted aiming to express the values of PMV, deriving a simplified comfort index for rooms conditioned by split-type systems based on dry-bulb air temperature and air speed. The purpose of this adjustment is to obtain an equation that provides the value of the comfort index for cooling purposes. Thus, for a certain condition of use, one can predict what will be the value of PMV in an occupied environment, enabling the implementation of a control system of the comfort according to this new index (ICS). The variables considered in obtaining the curve were the air temperature (Tar) and the air velocity (Var), since these two variables can be controlled directly by the split-type system. The general purpose of this work is to provide experimental data for the development of a low-cost device to automatically control ICS-based thermal comfort in a space conditioned by a split-type system through a single and representative point within the classroom.
Multi-Objective Optimization of Parameters for Milling Using Evolutionary Algorithms and Artificial Neural Networks
Authors: Banerjee Amit , Abu-Mahfouz Issam , Rahman AHM Esfakur 
Published: January 2020

Abstract
Model-based design of manufacturing processes have been gaining popularity since the advent of machine learning algorithms such as evolutionary algorithms and artificial neural networks (ANN). The problem of selecting the best machining parameters can be cast an optimization problem given a cost function and by utilizing an input-output connectionist framework using as ANNs. In this paper, we present a comparison of various evolutionary algorithms for parameter optimization of an end-milling operation based on a well-known cost function from literature. We propose a modification to the cost function for milling and include an additional objective of minimizing surface roughness and by using NSGA-II, a multi-objective optimization algorithm. We also present comparison of several population-based evolutionary search algorithms such as variants of particle swarm optimization, differential evolution and NSGA-II.
Microfluidic Temperature Behavior in a Multi-Material 3D Printed Chip
Authors: Sanchez Derek , Nordin Greg , Munro Troy 
Published: January 2020

Abstract
As analysis systems shrink in size to microfluidic scales and devices, there is a need to improve temperature control in the microscale for temperature-sensitive processes. Technology that combines accurate temperature measurement and 3D spatial control of the temperature distribution is limited by common 2D layer-based microfluidic fabrication techniques but can be realized with 3D printed microfluidic chips. This work presents an iterative process to create a microfluidic chip using multi-material 3D printing to improve temperature sensing and create an even temperature around a target volume. Through an iterative process, verification is presented of fluorophore viability (specifically CdTe quantum dots) after being secured in place by cured PR48 3D printing resin, thus confirming the possibility of fluorescent thermometry as an accurate non-contact temperature sensing method. Numerical analyses of various geometries of chip design iterations are also presented verifying spatially even heating due to the placement of heating sources in the microfluidic chip. Combining the fluorescent thermometry and improved heating will lead to improved temperature control in microfluidic devices.
Measuring the Effect of Local Commercial Roofing Samples on the Thermal Behavior of a Social Interest Dwelling Located in Different Climates in Ecuador
Authors: Litardo Jaqueline , Macías José , Hidalgo-León Rubén , Cando Maria Gabriela , Soriano Guillermo 
Published: January 2020

Abstract
This paper presents an assessment of the effect of the solar reflectance of roofing assemblies on the thermal behavior of a social interest dwelling model located in six representative cities in Ecuador. The model house complies the Ecuadorian building standard. The solar reflectances of 23 local commercial roofing samples were measured following the E1918A Procedure. The thermal behavior of the dwelling was simulated in EnergyPlus. The models use input data, such as: loads and schedules, provided by previous studies on social dwellings. The hours of thermal discomfort based on ASHRAE Standard 55-2013 adaptive model were obtained for each case by varying the experimental solar reflectance of the roofing sample and meteorological data for each hourly time step calculation. Results indicated that the 1808001-50 sample provided between 3240 to 5524 discomfort hours in all cases, being the most suitable roofing assembly for all studied cities due to its higher solar reflectance.
Analysis of a Double Inlet Gerotor Pump: A Dynamic Multi-Phase CFD Approach Accounting for the Fluid Compressibility and Temperature Dependent Properties
Authors: Milani Massimo , Montorsi Luca , Terzi Stefano , Storchi Gabriele , Lucchi Andrea 
Published: January 2020

Abstract
The paper analyzes the fluid dynamic performance of a double inlet Gerotor pump by means of a multi-phase and multicomponent CFD approach. The numerical simulation includes the full 3D geometry of the pump as well as the real physics of the compressible hydraulic fluid and the rotating dynamic motion. The aeration and cavitation phenomena are included in the analysis adopting the Rayleight-Plesset equation and inertia controlled growth model for bubble formation. Cavitation and aeration phenomena are detected, especially when intake pressure is lower than atmospheric pressure. The influence of the fluid temperature variation on the component performance is also numerically predicted. The accuracy of a detailed modelling of the fluid properties variation with respect to the temperature and pressure is addressed and the effects on the numerical results is investigated.
The rotational speeds of the internal and the external gears of the pump and the engagement between the teeth are addressed by means of an overset mesh approach. Constant leak height is considered between the gears and the case, while the overset mesh approach is adopted in order to accurately predict the leakage due to the teeth engagement.
This numerical approach enables to investigate the dynamic performance of Gerotor gear pumps in terms of flow rate and pressure ripples and volumetric efficiency under standard and critical (actual) operating conditions. Good agreement between numerical and experimental results was found for specific operating conditions.
Effects of Drive Side Pressure Angle on Gear Fatigue Crack Propagation Life for Spur Gears With Symmetric and Asymmetric Teeth
Authors: Karpat Fatih , Dogan Oguz , Yilmaz Tufan , Yuce Celalettin , Kalay Onur Can , Karpat Esin , Kopmaz Osman 
Published: January 2020

Abstract
Today gears are one of the most crucial machine elements in the industry. They are used in every area of the industry. Due to the high performances of the gears, they are also used in aerospace and wind applications. In these areas due to the high torques, unstable conditions, high impact forces, etc. cracks can be seen on the gear surface. During the service life, these cracks can be propagated and gear damages can be seen due to the initial cracks. The aim of this study is to increase the fatigue crack propagation life of the spur gears by using asymmetric tooth profile.
Nowadays asymmetric gears have a very important and huge usage area in the industry. In this study, the effects of drive side pressure angle on the fatigue crack propagation life are studied by using the finite element method. The initial starting points of the cracks are defined by static stress analysis. The starting angles of the cracks are defined constant at 45°. The crack propagation analyses are performed in ANSYS SMART Crack-Growth module by using Paris Law. Four different drive side pressure angles (20°-20°, 20°-25°, 20°-30° and 20°-35°) are investigated in this study. As a result of the study the fatigue crack propagation life of the gears is increased dramatically when the drive side pressure angle increase. This results show that the asymmetric tooth profile not only decrease the bending stress but also increase the fatigue crack propagation life strongly.
Development of Thermally Conductive Polymer/CNF Nanocomposite Materials via PolyJet Additive Manufacturing by Improvement of Digital Material Design
Authors: Ulu Furkan Ismail , Mohan Ram , Tomar Ravi Pratap Singh 
Published: January 2020

Abstract
PolyJet printing technology allows building polymeric materials with complex multi-material structures in the resolution of tens of microns layer thickness providing high control over the entire 3-D part. On the other hand, thermally conductive polymer/CNF nanocomposite materials offer new opportunities for replacing metals in industry and applications that require heat dissipation to avoid degradation of materials prematurely. CNFs are one of the best promising filler types to enhance thermal conductance of polymers. However, experimental thermal conductivities of polymer/CNF nanocomposites are significantly low compared to the intrinsic thermal conductivity of CNFs. Present work focused on selectively addition CNF fillers to form a thermally conductive path which helps to control dispersion and alignment. PolyJet printing forms the material and the structure simultaneously which allows the control over the material distribution and morphology on entire 3-D parts while providing possibilities to manipulate the design and create a conductive path. In the present research, improvement of thermal conductivity of Polymer/CNF nanocomposites via PolyJet printing using voxel digital printing method was investigated. Samples were designed as VeroClear material, VeroClear with CNFs, VeroCyan material, VeroCyan with CNFs. DSC and TPS were used to perform the thermal characterization of the samples.
Optimizing Bolting Configurations in a Pressure Vessel
Authors: Mancovsky Justin , Ferriera Jarod 
Published: January 2020

Abstract
Control valve standards and guidelines (specifically ASME B16.34), which have been in place for over 50 years, have undergone incremental changes. These standards are important as they prevent field failure by maintaining system performance and ensuring the safety of workers and other components in proximity to valves.
New control valve technologies represent a significant alteration in valve geometry and operating characteristics. During the development, the valve body geometry and design requirements were closely examined. The authors have identified opportunities for adjustments to ASME B16.34 design requirements through the review of related standards and the process of design optimization.
Specifically, this paper reviews the design requirements for valve body joints and their bolting configurations. It examines bolt properties, including yield stress, proof strength, and allowable stress, through the ASME Boiler and Pressure Vessel Code [1], ASME B16.34 [2], ASME B16.5 [3], and ASME B31.3 [4].
It is proposed that the design requirements found in ASME B16.34 Section 6.4, Valve Joints, be adjusted such that the allowable stress limit for high strength bolts can be fully utilized.
Finite Element Analysis is performed to examine those dynamic loading scenarios that are accounted for in the determination of allowable stress - temperature gradients (which cause pipe expansion and contraction), cyclic fatigue, vibration, impact (flashing or hydraulic shock), seismic events, and live loads (ice/snow).
Data from the analysis is presented to show that the modified bolting configuration can withstand the maximum pressure and temperature requirements. Alternative bolting configurations can be shown to conform to the allowable stress requirements, allowing for design optimizations that reduce the overall size and weight of a valve.
Modifications to ASME B16.34 and ASME B16.5 are therefore recommended. When the proposed bolting configuration was applied to a DN25 valve, we were able to achieve weight savings of 4 lbs., along with a 0.6” reduction in outer diameter. These optimizations allow for manufacturing cost savings including cost of hardware, raw materials, and machining. This optimization can be extrapolated for greater savings with larger valve designs.
Characterizations of the Paper-Based Microfluidic Devices Used for Detecting Fentanyl and Related Synthetic Opioids
Authors: Rahman M. Shafiqur , Chakravarty Uttam K. 
Published: January 2020

Abstract
The design and analysis of a paper-based microfluidic analytical device (μPAD) are presented in this paper for the detection of fentanyl and related synthetic opioids. Fentanyl, a synthetic opioid, is an extremely fast-acting synthetic narcotic analgesic having a high potency of approximately 100 to 200 times that of morphine. Detection of fentanyl can be done by colorimetric assays, i.e., spot tests with paper strips and μPADs which offer speed, simplicity of operation, portability, and affordability. The microfluidic behavior of liquid specimen and paper in the μPADs and test strips play a significant role in drug detection methods. Therefore, the study contains the fabrication of the test device using 3D printing and analysis of microfluidic behavior of the paper-based fentanyl test device. A multiphase computational fluid dynamics (CFD) model of a 3D microchannel is developed to evaluate the microfluidic properties. The CFD model incorporates the properties of cellulose and fentanyl solution to determine the flow parameters using the volume of fluid method. Wicking in the cellulose paper is studied analytically considering the Lucas-Washburn equation and Darcy’s law. Experiments with the fabricated μPAD and commercial test-kit samples are also conducted to compare the experimental results with the results for the flow parameters found from the numerical simulation.