bluuebunny/crossref_metadata_2025_split huggingface dataset:
Adequate Lubrication As the First (and Often Only) Line of Defense Against Dust Explosions in Grain Elevators
Authors: Ramirez Juan C. , Aljazireh Kamal , Lane James F. 
Published: February 2021

Abstract
Finely divided solid materials (e.g., dusts and fines), when dispersed in the air, can fuel particularly violent and destructive explosions. In this paper we will discuss a case study involving a dust explosion in a grain elevator and how a careful bearing greasing policy could have avoided it.
We present the most common conditions that lead to bearing overheating which can serve as the ignition source for a dust explosion. Additionally, we stress the need to raise awareness among operators about the wide variety of greases available, and given this wide variety, it is critical for facilities to ensure they use a grease with characteristics as close as possible as these recommended by the equipment manufacturer.
Development of Critical Heat Flux Correlation in Circular Pipe Sections With Vertically Downward Two-Phase Flows by Numerical Analysis and Comparison With Experimental Correlation
Authors: Sripada Rajeshwar , Veeredhi Vasudeva Rao , Mendu Siva Subrahmanyam 
Published: February 2021

Abstract
Critical heat flux (CHF) and premature tube burnout are the common failure modes observed in steam water two-phase flows. Unlike the vertically upward two-phase flows, the vertically downward two-phase flows pose significant challenges including two-phase flow instabilities and premature tube burnout arising due to competing behavior between the buoyancy effects on vapor bubble and momentum and gravitational force acting on the liquid. Experimental investigations were conducted previously to understand the CHF at atmospheric pressures. There were very limited number of numerical analysis conducted in vertically downward flows using commercially available software and at such low-pressure conditions. In the current investigations, numerical simulations were carried with commercially available computational fluid dynamics software Fluent for vertically downward two-phase flows up to pressures of 5 bar. The magnitude of CHF from numerical investigations was compared with the experimental results conducted in house up to 5 bar and including the sub-cooling effects. The numerical results tend to agree with the experimental data at lower flow rates and at all pressures considered, but tend to deviate significantly at higher flow rates and at all pressures. Finally, A CHF correlation is proposed as a function of mass flux, inlet temperature and pressure. The proposed CHF correlations fits in with an average deviation of 16% and a standard deviation of 21%.
3D Printed Cellular Structure Materials Under Impact and Compressive Loading
Authors: Ardebili Mahmoud K. , Ikikardaslar Kerim Tuna , Ehrnfeld Colt , Delale Feridun 
Published: February 2021

Abstract
Advances in field of lattice structure design has become possible mainly due to the emerging capabilities of additive manufacturing (AM) or 3D printing. Lattices have the potential to reduce solid volumes, giving advantages such as weight reduction, decreased part production cost and ability to absorb energy under compressive and impact loading. These materials are anisotropic due to structural geometry and the additive nature of 3D-printed layers, which stack mainly in Normal or Lateral direction to the applied load. In this study 3D printed materials were fabricated that are nearly isotropic and are also lighter than base material. The lattice structure was formed using strut-based cell topologies that are adjoined as tetrahedrons. Two different tetrahedron density specimens were produced with Acrylonitrile Butadiene Styrene (ABS) using a Fusion Deposition Modelling (FDM) printer. The fabricated specimens were then tested for impact and compression capabilities. For comparison purposes, solid specimens with the same overall dimensions and highest infill ratio were also produced and tested. After compression and impact testing, results indicated that solid specimens’ impact energy absorption is higher with lateral stacking order relative to load, and compression resistance is higher for normal stacking order. The tetrahedron-filled specimens exhibited minimal stacking directional dependency and the higher count tetrahedron specimens provided more impact energy absorption and more resistance to compression than the lower count one. The normalization of specimens with respect to their weight indicated high density tetrahedron specimens’ impact energy absorption is nearly equal to that of solid specimens’. These results are initial steps in creating lattice structured materials that are isotropic, lighter and stronger than the base material.
Particle Transport Coefficient (PTC) and Phase-Efficiency Diagram: A New Perspective to Evaluate Three-Phase Particle-Laden Flow
Authors: Zhang Zhifeng , Pruvot Antoine Jean-Claude Jacques , Cisternas Pablo , McAndrew James 
Published: February 2021

Abstract
Many technologies have been developed to improve the ability of fluids to transport particles. However, the evaluation of particle transport efficiency remains challenging, especially in complex flow such as three-phase flow. In the present research, theoretical and experimental work is conducted to develop a new perspective of evaluating particle transport technologies, particle transport coefficient (PTC) as the particle transport distance per unit volume of water consumption considering the transport efficiency and environmental cost. The mathematical form of the PTC for the steady-state transport case is derived, followed by three special transport cases: (a) PTC = 0 when particle settled or stuck, (b) PTC = infinity in the vertical direction, considering gravity or buoyant with carrier fluid stationary, while PTC = 0 in a horizontal pipe due to particle settlement; and (c) PTC = 2 for an infinitely small particle at the center of a fully-developed laminar flow in a pipe. Furthermore, the fluid property and surface property influence on PTC are experimentally demonstrated. We believe the proposed approach can promote the development of particle transport technologies.
Automated Drilling of High Aspect Ratio, Small Diameter Holes in Remote, Confined Spaces
Authors: Rittikaidachar Michal , Hobart Clint , Slightam Jonathon E. , Su Jiann-Cherng , Buerger Stephen P. 
Published: February 2021

Abstract
We describe the development and benchtop prototype performance characterization of a mechatronic system for automatically drilling small diameter holes of arbitrary depth, to enable monitoring the integrity of oil and gas wells in situ. The precise drilling of very small diameter, high aspect ratio holes, particularly in dimensionally constrained spaces, presents several challenges including bit buckling, limited torsional stiffness, chip clearing, and limited space for the bit and mechanism. We describe a compact mechanism that overcomes these issues by minimizing the unsupported drill bit length throughout the process, enabling the bit to be progressively fed from a chuck as depth increases. When used with flexible drill bits, holes of arbitrary depth and aspect ratio may be drilled orthogonal to the wellbore. The mechanism and a conventional drilling system are tested in deep hole drilling operation. The experimental results show that the system operates as intended and achieves holes with substantially greater aspect ratios than conventional methods with very long drill bits. The mechanism enabled successful drilling of a 1/16″ diameter hole to a depth of 9″, a ratio of 144:1. Dysfunctions prevented drilling of the same hole using conventional methods.
PEM Fuel Cell Electrodes Surface Defects Impact on the System Performance
Authors: Fontalvo Victor M. , Illera Danny , Sanjuan Marco E. , Gomez Humberto A. 
Published: February 2021

Abstract
Fuel cell system manufacturing process is not a defect-free process, therefore, the impact of typical defects in the electrodes (i.e. Gas Diffusion Layer (GDL)) surface has to be taken into consideration when the fuel cell system is being designed. To assess the impact of the defect on the performance, two approaches were taken into consideration. Initially, the fuel cell system was simulated using a unidimensional (1D) dynamic model which took into consideration mass transfer, heat transfer, and electrochemical phenomena. The second approach was experimental, using a 5 sq.cm PEM fuel cell, the impact of the GDL porosity on the fuel cell system was studied. Also, the system response under different load changes was investigated. After that, experimental results are presented to give a better insight into the phenomena analyzed, mainly on the dynamic system response.
Cracks and catalyst clusters were the main defects analyzed, both of them were observed in new membranes assemblies. To control the defects, new membranes assemblies were tested, and after that, defects were induced using Nafion solution and catalyst powder to emulate the presence of catalyst clusters. For the cracks, some fibers in the GDL cloth were cut to emulate the defect. Membranes now with defects were tested again to compare its performance and detect any performance loss due to the physical changes in the electrodes.
Results indicate a strong correlation between the porosity and the supply air pressure and the system time constants. Also, the impact of the defects was evidenced in the dynamic system response, after step changes in the operating conditions.
Acoustic Metamaterial With Air-Backed Diaphragm for Broadband Absorption: A Preliminary Study
Authors: Dong Qian , Song Xiaolei , Ray Subhrodeep , Liu Haijun 
Published: February 2021

Abstract
Membrane-based acoustic metamaterials have been reported to achieve 100% absorption, the acoustic analogue of photonic black-hole. However, the bandwidth is usually very narrow around some local resonance frequency, which limits its practical use. To address this limitation and achieve a broadband absorption, this paper first establishes a theoretical framework for unit cells of air-backed diaphragms, modeled as an equivalent mass-spring-dashpot system. Based on the impedance match principle, three different approaches are numerically investigated by tuning the cavity length, the static pressure in the cavity, and the effective damping of perforated plates. A prototype with polyimide diaphragm and 3D printed substrate is then fabricated and characterized using an acoustic impedance tube. Preliminary experiments show the feasibility to achieve an absorption bandwidth of ∼200 Hz at center frequency of 1.45 kHz. This work pays the way for developing a sub-wavelength light weight broadband acoustic absorber for a variety of applications in noise control.
Design of Omnidirectional Robot Using Hybrid Brain Computer Interface
Authors: Ghoslin Bryan , Nandikolla Vidya K. 
Published: February 2021

Abstract
The paper presents a Brain-Computer Interface (BCI) controller for a semiautonomous three-wheeled omnidirectional robot capable of processing real-time commands. The kinematical model of the omni-directional robot and the software architecture of the overall hybrid system with motion control algorithm are presented. The system design, acquisition of the electroencephalography (EEG) signal, recognition processing technology and implementation are the main focus. Signals are recorded and processed by a program called OpenVibe. Preprocessed signals are cleaned by EEGLAB and used to train OpenVibe classifiers to accurately identify the expected signals produced by the users. Once identified, the controller converts the signal into input commands {forward, left, right, rotate, stop}, which are written in the Python syntax and delivered to the robot system. The robot has three degrees of freedom (DoF) allowing it to traverse its environment in any direction and orientation. The sensor system provides feedback allowing for the semi-autonomous control to avoid obstacles. Overall, this paper demonstrates the architecture of the hybrid control system for omni-directional robot using BCI. The developed system integrates the EEG signal to control the motion of the robot and the experimental results show the system performance and effectiveness of possessing the user’s EEG signals.
Hydrokinetic Vortex Induced Vibration (VIV) Energy Harvester
Authors: Zhou Xiaoyu , Roussinova Vesselina , Stoilov Vesselin 
Published: February 2021

Abstract
This paper investigates the performance of vortex-induced vibration (VIV) energy harvester in low-speed water flow. The proposed VIV harvester is extracting hydrokinetic energy from the flowing current and transferring it into mechanical vibrations. The vibrations are further converted into electrical energy using the piezoelectric transducer to supply the modern demand for energy-consumption. To meet the demand, the single harvester is analyzed to determine the suitable geometry for the bluff body that is sensitive to the low-speed flow. Furthermore, the converter must be able to harvest vibrations of varying amplitudes and frequencies. To maximize the power output, different array configurations of multiple bluff bodies are examined. A single positively buoyant elastically mounted cylinder is tested experimentally and at a low flow speed of 0.3 m/s, it can harvest vibrations with an average frequency of 1.8 Hz and peak to peak amplitude of 1.5d, where d is the diameter of the bluff body. It was found that for an array consisting of ten bluff bodies, the average frequency and peak to peak amplitude increases to 2.09Hz and 1.54d, respectively.
Rate Dependent Material Model for Helmet Pads
Authors: Zhang Timothy G. , Fulton A. H. , Ravi-Chandar K. , Satapathy Sikhanda S. 
Published: February 2021

Abstract
Foam pads are commonly used in sports and military helmet for energy absorption, form-fitting and comfort. Both for low velocity and high velocity applications, their rate-dependent mechanical properties need to be characterized to understand their ability to effectively modulate the transmitted stress pulse. Impact experiments were conducted on bilayer helmet pads at a range of velocities covering low to medium rates up to ∼7000/s. Images from high-speed camera were used to construct x-T diagrams to measure the shock speeds from the impact experiments. Numerical simulations were carried out to validate a foam pad model and to understand experimental uncertainties. The scatter in the measured shock speeds was found to be related to the scatter in the material properties.
An Investigation on the Design of Formate and Generate Face Milled Hypoid Gears
Authors: Yılmaz Tufan Gürkan , Kalay Onur Can , Karpat Fatih , Doğanlı Mert , Altıntaş Elif 
Published: February 2021

Abstract
Hypoid gears are transmission elements that transfer power and moment between shafts whose axes do not intersect. They are similar in structure to spiral bevel gears. However, there are many advantages compared to spiral bevel gears in terms of load carrying capacity and rigidity. Hypoid gear pairs are mostly used as powertrain on the rear axles of cars and trucks. Hypoid gears are manufactured by two essential methods called face-milling and face-hobbing, and there are mainly two relative kinematic movements (Formate® and Generate). In this study, the gears produced with the Face-milling method are discussed. Face milled hypoid gears can be manufactured with both Formate® and Generate, while pinions can only be manufactured with the Generate method. The most crucial factor that determines the performance of hypoid gears is the geometry of hypoid gears. The gear and pinion geometry is directly dependent on the tool geometry, machine parameters, and relative motion between the cradle and the workpiece. The gear geometry determines the contact shape and pressure during power transmission.
In this study, the mathematical equation of the cutting tool is set. After that, using differential geometry, coordinate transformation, and the gearing theory, the mathematical equation of hypoid gear is obtained.
Stochastic Optimization of a Horizontal-Axis Composite Wind Turbine Blade
Authors: Thapa Mishal , Missoum Samy 
Published: February 2021

Abstract
In this paper, the stochastic optimization of a horizontal-axis composite wind turbine blade is performed. Wind energy has become widely popular in recent decades as an alternative source of energy and many studies have been devoted to finding an optimal wind turbine blade using deterministic optimization. However, the actual responses of the wind turbine blade such as power generation are affected by the stochastic nature of wind, uncertainties in material properties and modeling parameters, and so on. This can have an undesirable impact on the performance and reliability of blades, which demands the consideration of uncertainties during optimization. To this end, a surrogate-based stochastic optimization of a wind turbine blade considering the influence of randomness in wind speed on power generation was studied. A slight gain in average power over the baseline blade was obtained and it demonstrated the promise of the presented framework for the design of wind turbine blades.
Assessment of Three-Dimensional Engagement Levels in a Global Peer Learning Environment
Authors: Wang Chu-Yi , Bessell Mary , Lu Stephen 
Published: February 2021

Abstract
The global learning classroom is an emerging educational trend. The iPodia alliance promotes its peer-learning pedagogy by offering engineering classes with universities around the world. Students’ engagement as one of the important metrics to assess the effectiveness of education design methodology has been under considerable interest for several years. Tri-engagement, comprised of behavioral, cognitive, and emotional engagement provides a comprehensive assessment of learning success. This paper illustrates how a tri-engagement assessment was implemented in a global learning environment and examines the effectiveness of the peer-learning pedagogy in such highly diverse environment. This paper proposes a quantitative method using a modified Likert scale to assess students’ tri-engagement levels comprised of student and teaching assistant surveys, video observations, and analysis of facial emotion recognition, through preparation, data collection, and analysis stages. Comparisons of tri-engagements between the instructor-student activities and the peer-peer discussions, different continent regions, and on-site/remote learning are offered. Results show that the overall iPodia peer-learning activities experienced all positive tri-engagement levels and were not significantly affected by the region diversity (&lt; 6% difference) or the remote learning (&lt; 3% difference) of the iPodia learning classroom. That preliminarily proved that the iPodia peer-learning pedagogy maintains positive tri-engagements in a global engineering class. Additional findings were that the self-raters and observers experienced students’ cognitive engagement differently, and cultural difference would mainly affect students’ behavioral engagement, but unfamiliarity of the content may increase their emotional engagement.
Experimental and Numerical Study of a Latent Heat Thermal Energy Storage Unit Enhanced by Fins
Authors: Hockins Addison , Moretti Samantha , Mahdavi Mahboobe , Tiari Saeed 
Published: February 2021

Abstract
Latent heat thermal energy storage (LHTES) systems are used to store thermal energy and release it for later use by melting or solidifying a phase change material (PCM). One problem associated with latent heat thermal energy storage systems is the low thermal conductivity of most commercially aviable phase change materials. This can have a significant negative effect on the thermal performance of the system by leading to a longer charging or discharging process. Several passive heat transfer enhancement techniques are used to resolve this issue. Common passive heat transfer enhancement techniques include inserting fins and extended surfaces into the PCM, embedding heat pipes or other two-phase heat transfer devices within the PCM, dispersion of highly conductive nanoparticles in the PCM, and impregnation of highly conductive porous media with the PCM. The current study analyzes the effect of a fin-based enhancement technique on the thermal performance of a latent heat thermal energy storage unit. Copper fins are attached annually around the central pipe inside the PCM. A transient two-dimensional numerical model technique is developed using ANSYS FLUENT 19.0 to simulate the operation of the system. Baseline tests have been conducted experimentally for a system without fins to validate the numerical model. The results obtained from the numerical modeling are in good agreement with those of the experimental testing. Based on the experimental testing, the total charging time of the system using hot water at 70°C and flow rate of 7.57 L/min is around 47.9 hours which is very close to the prediction by the numerical model which is 48 hours. Numerical modeling of the system with 10 fins and 20 fins found that the charging time was decreased by 68.9% and 73.7%, respectively. The discharging time was also decreased by 73.2% and 79.1%, respectively.
Effect of Loading Direction and Bone Density Distribution in Assessing Hip Fracture via Finite Element Analysis
Authors: Awal Rabina , Faisal Tanvir R. 
Published: February 2021

Abstract
An accurate assessment of hip fracture risk requires a proper consideration of parameters affecting the fracture. In general, hip fracture is affected by bone morphology, bone mineral Density (BMD), and load amount. Hip fracture is an outcome of the interaction of all those parameters including loading directions. Assessing the effect of the parameters individually may not correctly reflect the root cause of the hip fracture. Hence, this research aims at analyzing the significance of parameters and their interaction. A multivariate regression model was used considering bone density (ρash), different loading directions during sideways fall, represented by load angle (α) on the coronal plane and angle (β) on the transverse plane as independent parameters and Fracture Risk Index (FRI) as a dependent parameter. The statistical results showing the significant value of 0.7321 for α, and 0.0001 for β and ρash indicates that the effect of loading direction about femoral shaft on the coronal plane (α) does not have impact on fracture risk while loading direction about femoral neck axis on the transverse plane (β) and ρash have the significant impact. Furthermore, the analysis of the interaction of parameters shows that the impact of β on fracture risk may depends more on bone density as the significance of interaction of β and ρash is 0.0001.