bluuebunny/crossref_metadata_2025 huggingface dataset:
Construction and Testing of Small-Scale Transformable-Hull Concept Boat
Authors: Whitworth Phillip , James Cole , Matveev Konstantin I.
Published: January 2022

Practically all marine vessels have fixed-geometry hulls. This limits their capabilities and high-performance regimes to a limited set of operational conditions. Having a transformable or adaptive hull structure can help maximize ship’s operational performance for various scenarios. In this work, a transformable concept boat is conceived that can change its configuration from monohull to twin-hulled configuration. A catamaran is desirable for carrying volumetric cargo or creating a large deck space that can serve, for example, as a launch pad for aircraft, while more compact monohulls can be more easily stored or operated in restricted environments. A monohull and a catamaran also have different stability, hydrodynamic, maneuvering and seakeeping characteristics. In the present effort, a small-scale model boat has been constructed with two hulls that can be brought together or separated using an expansion mechanism driven by a servo motor. This model setup has been equipped with propulsors, batteries, and control and communication modules for radio-controlled operations. In addition, a remote data acquisition system was assembled for measuring boat’s kinematic and powering characteristics. Results of initial tests with the small-scale transformable boat in an open water reservoir are reported and discussed in this paper.
Optimization of the Installation Sequence for the Temporary Fasteners in the Aircraft Industry
Authors: Pogarskaia Tatiana , Lupuleac Sergey , Shinder Julia , Westphal Philipp
Published: January 2022

Riveting and bolting are common assembly methods in aircraft production. The fasteners are installed immediately after hole drilling and fix the relative tangential displacements of the parts, that took place. A proper fastener sequence installation is very important because a wrong one can lead to a “bubble-effect”, when gap between parts after fastening becomes larger in some areas rather than being reduced. This circumstance affects the quality of the final assembly. For that reason, the efficient methods for determination of fastening sequence taking into account the specifics of the assembly process are needed. The problem is complicated by several aspects. First of all, it is a combinatorial problem with uncertain input data. Secondly, the assembly quality evaluation demands the time-consuming computations of the stress-strain state of the fastened parts caused by sequential installation of fasteners. Most commonly used strategies (heuristic methods, approximation algorithms) require a large number of computational iterations what dramatically complicates the problem. The paper presents the efficient methods of fastener sequence optimization based on greedy strategy and the specifics of the assembly process. Verification of the results by comparison to commonly used installation strategies shows its quality excellence.
A Virtual Reality Laboratory Implementing Lean Manufacturing: Case Applied at Mechatronic Technical School
Authors: Leticia Neira-Tovar , Isaías Almaguer Rosales , Lucero Cavazos , Radoslav Palacka
Published: January 2022

Nowadays information technologies have been essential for the advancement of teaching and professional development. The world has experienced a pandemic crisis based on a virus called Sars-cov 2, this changed the way of living and the way of learning, now we face the challenge of learning to distance, the virtual laboratory allows us to acquire knowledge and develop skills based on a series of practices that the student carries out, this integrates Lean Manufacturing tools in order to give added value to the client, and by effect reducing waste to the company, which is one of the characteristics most important in lean philosophy.

The purpose of this work is to facilitate the scope of the topics giving students the use of a quality process into the virtual reality simulator that ensure the quality of knowledge transmission based on practices designed to learn mechatronics and lean manufacturing topics.

A virtual reality application is used to simulate a physical laboratory, which consists of: Research, Development and Testing steps, using Unity and 3DMax software. The virtual laboratory for a distance modality in the mechatronics career was carried out at technical high school, and developed by students of the mechanical and electrical engineering faculty, and currently designed for 2 practices, one of them is based on a DMAIC cycle [1].
Water Management for an Electrochemical Gas Separation and Inerting System
Authors: Aryal Utsav Raj , Prasad Ajay K.
Published: January 2022

Fuel tank inerting is necessary to promote aircraft safety. Typically, this is accomplished by supplying an inert gas like nitrogen into the ullage (air volume above the fuel) of the fuel tank. We have developed a novel on-board electrochemical gas separation and inerting system (EGSIS) to generate nitrogen enriched air (NEA) for fuel tank inerting. EGSIS is an externally powered device that functionally combines a polymer electrolyte membrane (PEM) fuel cell cathode with a PEM electrolyzer anode. Water management is important in such a PEM-based system because proton transfer requires proper hydration of the membrane. Extremes of both dryout and flooding conditions should be avoided for optimal EGSIS performance. Previous single cell EGSIS experiments revealed that supplying liquid water at the anode will maintain adequate membrane hydration even if the cathode is operated under very dry conditions. However, it was difficult to avoid flooding at low cathode air stoichiometries when parallel flow field channels were employed. Here, we employ serpentine and interdigitated flow field channels, as well as a double-layer gas diffusion layer with graded hydrophobicity to mitigate flooding and improve water management.
Effects of Cutting Fluid Applications on Surface Integrity in Grinding of Weld Flash in Resistance Welded Alloy Steel
Authors: Rangasamy Nithin , Rakurty C. S.
Published: January 2022

The effect of the grinding process for weld flash removal on the surface integrity of the welded joint has not been researched. The surface integrity of the welded joint is essential for the bandsaw blade life and to prevent any premature failure at the weld joint due to fatigue loading (a band saw blade undergoes mainly cyclic bending fatigue during its service). In this study, the effects of using different cutting fluid combinations on the grinding of weld flash in medium carbon alloy steel were carried out. The use of compressed air as a sustainable solution for grinding weld flash was explored. Experimental investigation of four different cutting fluid applications (dry/no cutting fluid, compressed air, minimum quantity lubricant using vegetable oil, and minimum quantity coolant used water-soluble oil) was carried out. Aluminum oxide grinding wheel at constant cutting speed was used for the study. The surface roughness, sub-surface residual stresses, and microhardness of the ground region were measured for all experimental conditions. This is a first-of-the-kind study on the effect of the flash removal process on the surface integrity of the welded joint. The results show that the surface integrity of the welded joint is significantly influenced by the cutting fluid application used during the grinding process of the flash. This research indicates that it is essential to use cutting fluid during the grinding process of the weld flash. Dry grinding, the current industry standard for grinding weld flash in band saw blades, produced tensile residual stresses, had the highest subsurface thermal damage, and produced the highest surface roughness. In contrast, the sustainable solutions suggested in this research can increase the fatigue life of the ground joint and increase the tool life of the grinding wheels. This study provides the road map for selecting the cutting fluid application for grinding weld flash produced by the resistance welding process in the band sawing industry.
Effect of Moisture Absorption on the Tensile and Flexural Properties of Glass Fiber Reinforced Composite Materials
Authors: Prakash Raghu V. , Viswanath Vishnu
Published: January 2022

The use of Glass fiber reinforced plastics (GFRP) in underwater applications has been increasing in recent times, due to its superior durability and chemical stability in corrosive environments compared to metals. However, penetration of moisture in to the polymer matrix can adversely affect the mechanical properties of composite materials. In this study, the effect of exposure to plain water and simulated sea water (3.5% by weight NaCl salt) water on the mechanical properties of GFRP specimens has been analyzed. Tensile and three point bend tests were conducted on composite specimens with different moisture contents to characterize the mechanical degradation due to moisture absorption. Gravimetric tests were conducted on specimens to calculate the moisture absorption parameters. The results indicate that plain water is absorbed at a faster rate compared to salt water. Using these parameters, a transient moisture diffusion model was developed using commercial finite element software ABAQUS®. The results of tensile and three point bend testing indicate that both tensile and flexural properties of glass fiber reinforced epoxy composites degrade with exposure to plain water and salt water. Further, a coupled hygro-mechanical model was developed in ABAQUS® and the simulation results were compared with actual test results. Scanning electron Microscopy was used to examine the fracture surface of failed specimens. The cause for mechanical degradation seems to be the deterioration of fiber-matrix interface due to the penetration of water molecules.
A Study on the Performance of Solar Driven Absorption Chiller in Terms of Coefficient Of Performance and Exergy Efficiency
Authors: Nitsas M. T. , Koronaki I. P.
Published: January 2022

Thermally driven chillers also known as sorption heat pumps have drawn considerable attention in recent years. They can be divided into two main categories: absorption (liquid-vapor) and adsorption (solid-vapor) systems. Even though sorption cycles have relatively lower coefficient of performance compared to conventional refrigeration cycles, however they prevail in terms of heat source, electric consumption for moving parts, mechanical wear etc. In order to enhance their environmentally friendly operation, sorption chillers can be driven by solar power.

In this study a solar driven absorption chiller which utilizes evacuated tubes collectors and intermediate heat exchanger is simulated. The model’s governing equations derived from the energy balance on each component of the system are solved numerically. The COP, the solar COP, the overall exergy efficiency, the required collectors’ surface and the collectors and tank normalized cost are calculated for various heat source temperatures. Moreover, all calculations are repeated for various values of heat exchanger effectiveness in order to determine the maxima and minima of the system’s operation. It is proved that the maxima are reached at lower inlet temperatures for higher values of the intermediate heat exchanger.
A Comparative Study of Various Deep Learning Techniques for Spatio-Temporal Super-Resolution Reconstruction of Forced Isotropic Turbulent Flows
Authors: Venkatesh T. S. Sachin , Srivastava Rajat , Bhatt Pratyush , Tyagi Prince , Singh Raj Kumar
Published: January 2022

Super-resolution is an innovative technique that upscales the resolution of an image or a video and thus enables us to reconstruct high-fidelity images from low-resolution data. This study performs super-resolution analysis on turbulent flow fields spatially and temporally using various state-of-the-art machine learning techniques like ESPCN, ESRGAN and TecoGAN to reconstruct high-resolution flow fields from low-resolution flow field data, especially keeping in mind the need for low resource consumption and rapid results production/verification. The dataset used for this study is extracted from the ‘isotropic 1024 coarse’ dataset which is a part of Johns Hopkins Turbulence Databases (JHTDB). We have utilized pre-trained models and fine tuned them to our needs, so as to minimize the computational resources and the time required for the implementation of the super-resolution models. The advantages presented by this method far exceed the expectations and the outcomes of regular single structure models. The results obtained through these models are then compared using MSE, PSNR, SAM, VIF and SCC metrics in order to evaluate the upscaled results, find the balance between computational power and output quality, and then identify the most accurate and efficient model for spatial and temporal super-resolution of turbulent flow fields.
Elliptical Machines Using Adjustable Linkages
Authors: Naif Ali Safdar , Zhou Hong
Published: January 2022

Elliptical machines are exercising or training machines that are used to imitate walking, jogging, running or climbing exercises. Different from treadmill machines, elliptical machine users never leave their feet away from the pedals, which reduces the pressures to the ankle, knee, and hip joints, and significantly lowers the impact injuries of users’ joints. The configurations of the elliptical motion commonly mimic the natural paths of the ankle, knee, and hip joints for walking, jogging or running, which further decreases the strains and stresses on users’ joints. In addition to low joint impact, another feature of elliptical machines is their integrated leg and arm movements that provide the dual lower and upper body exercises. Users of elliptical machines not only exercise their legs, but also push and pull the handlebars to strengthen their arms. Unlike treadmills, ellipticals are self-powered by user-generated motion and have no need for motor and belt conveyance. The closed trajectories of elliptical machines are generated through their linkages. The shapes and sizes of the closed trajectories depend on the linkage dimensions. The trajectory of an elliptical machine needs to meet the requirements for different exercises, and various short and tall people with a wide range of arm or leg sizes. If an elliptical machine has fixed linkage dimensions, its elliptical trajectory has only one shape and size, which does not provide flexibility. In order for an elliptical machine to have flexibility, its linkage has to be adjustable. Adjustable linkages are more difficult to design than linkages without adjustability. This research is motived by surmounting the challenges facing elliptical machines. Different types of elliptical machines (rear, front, and central drives) without and with adjustability are analyzed. Their elliptical output motions are simulated. The research results will provide useful guidelines for developing and promoting elliptical machines.
Acceleration Mechanism of Intergranular Cracking of SUS316L Under Creep-Fatigue Loading at Elevated Temperatures
Authors: Takahashi Yukako , Suzuki Ken , Miura Hideo
Published: January 2022

Austenitic stainless steels are used as heat-resistant steels because of their high corrosion resistance and strength at elevated temperatures. However, the fracture life of alloys under creep conditions at elevated temperatures was found to significantly decrease due to the acceleration of intergranular cracking. The drastic reduction in fracture life was caused by a change in the crack propagation path from transgranular to intergranular. It was also found that intergranular cracking occurred only by the interaction between temperature and mechanical stress even when the specimen was not in a corrosive environment. However, the mechanism of the acceleration of intergranular cracking is still unclear. Therefore, in this study, an intermittent creep and creep-fatigue tests were applied to SUS316L to visualize the degradation process of their micro textures. The degradation process of the crystallinity around grain boundaries in the alloy was investigated by EBSD (Electron Back-Scatter Diffraction) analysis. KAM (Kernel Average Misorientation) and IQ (Image Quality) value were used for the evaluation of the crystallinity and local plastic deformation, in other words, the total density of dislocations. It was found that the accumulation of fine voids started to appear around grain boundaries in the early stage of the lifetime and all the initial cracks were found to appear around grain boundaries perpendicular to the loading direction of the applied stress. It was confirmed that the intergranular cracks started to occur when dislocations accumulated around a grain boundary and the difference in the dislocation density between nearby grains reached a critical value. As a result of the analysis of the Schmid factor, it was confirmed that cracks occurred around grain boundaries composed of a grain with large absolute value of Schmid factor and the large difference in the Schmid factor with the nearby grain.
Influence Of Laser Induced Plasma on Material Removal in Micro-Drilling Underwater
Authors: Zheng Changlong , Shen Hong
Published: January 2022

Water-assisted ultrafast laser processing was proposed to solve the problem of surface quality in metal during laser micro-hole drilling. The percussion drilling process with different single pulse energies was tested under 10 mm water layer and in air. The morphologies of the laser induced plasma (LIP) were observed and recorded. The drilling depth and micro-hole radius were characterized by microscope and 3D surface profilometer. Experimental results show that the debris, spatter recast or others caused by the laser energy deposition are quickly transferred away, but the material removal performance caused by LIP under water is different from that in air. It is noteworthy that the drilling depth has been significantly reduced at all pulse energies owing to the shielding effect of water and LIP. But the micro-hole radius has increased several times after a sufficient pulse number, which is attributed to the defocusing effect of LIP. In order to explain the mechanism of underwater ablation characteristics, a model combining the LIP formation and evolution was developed to analyze the energy attenuation effect and the beam refraction effect by LIP underwater. Moreover, the annular morphology at the hole bottom under high pulse energy can also be explained by these two effects of LIP.
Establishment of the Off-Center Embedded Crack Stress Intensity Factor Database for Probabilistic Risk Assessment Based on Universal Weight Function
Authors: Xu Tongge , Ding Shuiting , Li Guo
Published: January 2022

Probabilistic failure risk analysis is important in recent development of airworthiness. In the fracture mechanics module of probabilistic failure risk analysis, efficient and accurate stress intensity factor (SIF) solutions are vital. Universal weight function (UWF) is a method that has a remarkable computational efficiency and high accuracy in SIF calculation. However, the concrete coefficients in the UWF remain unknown, and the rules of the geometric parameters and these coefficients have not been clarified. This limitation hinders the subsequent application of the method. This article discusses general off-center embedded cracks. The response surface method (RSM), as a means of database establishment, is used to construct the relations between the coefficients in the UWF and geometric parameters. The mean absolute percentage errors of the SIFs between UWF and finite element method are less than 4% within a certain range. Gaussian process regression is adopted to better fit the data, especially when the crack is near the plate boundary and the R-square is over 0.96. In addition, the effect of the offset distance on SIFs is discussed for a certain embedded crack in a given plate. Results show that changes in the SIFs are dependent on the plate boundary in the uniform stress field. However, stress predominates the changes in the SIFs when the crack is not very close to the plate boundary in the nonuniform distributed stress fields. The databases and discussion that followed can provide some reference and inspiration for further research.
EBSD Investigation of Ti6Al4V Alloy Processed by Constrained Groove Pressing and Heat Treatment
Authors: Bhardwaj A. , Gohil N. , Sharma A. , Lakshman Rao K. , Gupta A. K. , Kumar S. S. Satheesh
Published: January 2022

Ti6Al4V sheet metal has found significant applications in the aerospace, defence and biomedical sectors due to its high strength-to-weight ratio and excellent corrosion resistance. The texture plays an important role in tailoring the mechanical properties which can be modified via thermo-mechanical processing. Constrained groove pressing (CGP) is a well-known sheet metal severe plastic deformation (SPD) technique for grain refinement and enhancement of mechanical properties. In this work, high temperature CGP has been performed successfully on Ti6Al4V alloy at 550°C followed by heat treatment at 500°C. CGP and heat treatment led to grain refinement and formation of submicron size grains. The inverse pole figure (IPF) reveals the decrease in texture intensity of basal planes from 5.9 to 4.5 in CGPed Ti6Al4V. Heat treatment further reduced the IPF texture intensity to 3.5. Enhancement in mechanical properties such as YS, UTS and microhardness is also observed. Although slight enhancement is observed in yield strength, ultimate tensile strength has been improved by 21% after CGP and heat treatment. Up to 20% improvements in microhardness have also been observed in processed samples. CGP and heat treatment together can serve as an efficient technique for tailoring microtexture and mechanical properties of Ti6Al4V and other HCP alloys.
Conventional and Advanced Exergetic Analysis for the Combined Cycle of Power Plant With Gas Turbine of a Refinery
Authors: Fajardo Juan , Guette Dawing , Barreto Deibys , Cardona Camilo , Baldiris Ildefonso
Published: January 2022

This article shows the results of the performance study of a combined cycle plant made up of a Siemens STG-800 gas turbine and a MACCHI heat recovery boiler (HRSG) designed to produce 47.5 MW of electricity and 81908 kg / h of steam operating under ISO conditions (15 ° C and 60% relative humidity and 1 atm), the system is part of the steam and electric power generation section of a crude oil refinery in the city of Cartagena de Indias.

The objective of this research is to quantify the real inefficiencies in each of the equipment applying conventional and advanced exergetic analysis, to achieve this the investigation has been ordered as follows: first, the basic thermodynamics at the equipment boundaries is defined, define performance parameters that compare the adjustment of the thermodynamic model with the values provided by the manufacturer, the rate of exergy destruction and exergy efficiency are obtained from conventional analysis, advanced exergetic analysis allows obtaining avoidable, unavoidable, endogenous, exogenous exergies and the combined, finally, the mexogenous exergetic analysis allows to know the amount of energy that is lost due to the interactions between the equipment.

The thermodynamic model is adjusted with an average error of 2% using design KPIs such as net power, heat rate and thermal efficiency, it was obtained that the exergy destruction reaches 83.5MW, 15% is avoidable and the 8% is avoidable endogenous, the mexogenous analysis shows that inefficiencies in the compressor refer to all equipment, by focusing efforts on improving its conditions, up to 25% of the total exergy destruction can be recovered.
Do Long Aorta Branches Impact on the Rheological Properties?
Authors: Al-Rawi Mohammad , Al-Jumaily Ahmed , Belkacemi Djelloul
Published: January 2022

Current studies dispute the effect of the aorta geometry and branches on how the hemodynamics parameters develop along the branches in 3D models. In constructing and modelling the aorta geometry, it is necessary to incorporate the different lengths of the bifurcation and branches. Previous studies modelled the aorta with simplified assumptions (idealized model) which gave rise to some differences between the model and clinical outcomes. However, these differences are minimal, and the results can still be validated against clinical trials. The Computational Fluid Dynamics (CFD) methods can also accurately simulate the stresses affecting the artery wall and the dynamic behavior of the blood flow in its pulsatile form. Therefore, the outputs from CFD analysis can be used to reduce the risk of disease complications and enable a better understanding of the effects of hemodynamic stresses. A comparison of the behavior of the Time-Average Wall Shear Stress (TAWSS), Oscillatory Shear Index (OSI), and Relative Residence Time (RRT) against two lengths of bifurcations and in the presence of Non-Newtonian Power Law blood flow properties is presented in this work. This study investigates the cardiac cycle transient analysis using the Laminar inviscid flow in FLUENT, ANSYS 2020R2. The results are promising and give ample support for further development of new diagnostic tools based on the relationship between the Wall Shear Stress (WSS) derivatives: TAWSS and the OSI and the branches lengths.
Transitional Flow and Heat Transfer on the Pressure Surface of a C-D Compressor Blade
Authors: Katiyar S. , Sarkar S.
Published: January 2022

A large-eddy simulation (LES) is used here to investigate the laminar-turbulent transition on the pressure surface of a controlled-diffusion (C-D) compressor stator blade at a Reynolds number (Re) of 2.1 × 105. The objective of the present study is focused upon the transition mechanism on the pressure surface and associated heat transfer. Flow features appear laminar at the beginning, followed by the undulation of velocity fluctuations, attributing to the development of elongated streamwise streaks at 27% of the chord. These streaks undergo breakdown at the mid-chord region via a secondary instability. Resolved flow structures also elucidate the formation of abundant small-scale eddies via the appearance of hairpin structures an increase of the turbulent heat flux. The decay of these structures occurs as flow further evolves downstream, attributing to local flow acceleration.
Numerical Simulation of the Effect of Bonded Patch Repair on the Internal Stress Distribution
Authors: Sreenath A. M. , Prakash Raghu V.
Published: January 2022

Composite materials are used extensively in high-performance applications due to their superior mechanical properties and lower density. The composite materials are susceptible to impact damage, and repair of the damaged components is inevitable. Bonded patch repairs are used extensively in the aerospace industry to repair the low-velocity impact damage. Low-velocity impact on quasi-isotropic, carbon fiber reinforced polymer (CFRP) composites was numerically simulated using finite element analysis ev (FEA). Damage evolution and the failure of the repaired composite laminates under a monotonous uniaxial loading were evaluated using FEA for various patch repair configurations. Load displacement characteristics of pristine, impacted, and repaired specimens were simulated. The analysis indicates that impacted specimen has a lower load-bearing capacity than the pristine one. The specimen with the double-patch displayed superior load-bearing capacity and stiffness compared to the other repair configurations among the repaired specimens. Variation of stress and strain along the longitudinal and transverse directions were evaluated. The stress distribution in the pristine specimen was more uniform than the impacted one. The peak strain values of impacted and repaired specimens were significantly higher than that of pristine ones at the impacted location. A reduction of stress at the impacted location was noticed for the impacted and repaired specimen compared to the pristine one. The current study indicated comparable strength and rigidity for the repaired component and the pristine component. However, the localized stress distributions observed for the pristine, impacted, and repaired specimens were significantly different even though the overall load-bearing characteristics were comparable.
Load Path Analysis and Design for Stiffness of Bolted Electro-Magnetic Mass Drivers
Authors: Goyal Gaurav , Mehta Nagendra Kumar , Khatait Jitendra Prasad , Mukherjee Sudipto
Published: January 2022

Electro-magnetic mass drivers (EMD) are linear payload accelerators at the forefront of multi-physics technology that find use in various applications. In a homopolar variant of EMD, two electrically conductive rails are clamped at a set separation apart in an electrically insulating chamber formed of housing and elastic support. Preloaded bolts and clamping plates are used to minimize the rail deformation during operation. In literature, EMD is treated similarly to a T-shaped, bi-material bolted joint subjected to tensile loading. The difference is that, unlike in a bolted T-joint, two load paths are available during the bolting phase, and bolt preload gets distributed between housing and elastic support. However, during operation, the housing is not subjected to tensile loading. Therefore, the purpose of bolt preload taken up by the housing must be analyzed. This issue has not been addressed in any literature concerned with the design of bolted EMD. The load path in the initial clamping state and that in operation as a function of housing height H and clamp separation distance S is determined. It is observed that stiffness increases from 70.6 MN/m to 231 MN/m as H/S decreases. However, there is a slight decrease in EMD stiffness when the housing carries no preload. Reasons in support of eliminating the housing are provided, and consequences are discussed. The clamp plates suffer adverse bending effects when housing is removed. The EMD section is altered, and the material is aligned in the load path direction to reduce the bending effect of loading. Shape-optimized clamping plates provide improved stiffness while minimizing the peak stress levels by 36%, and EMD section mass is reduced by 10%. The analysis and design method proposed in this paper provides a theoretical basis for designing ultra-stiff and lightweight EMD.
Evaluation of Hydraulic and Thermal Characteristics of Interconnected Parallel Flow Mini Heat Sink
Authors: Uddin Md Wasi , Ayon Hassan Shahriar , Mehrab Tahmid Mohammad , Sifat Najmus Saquib
Published: January 2022

This study represents a numerical investigation of the compatibleness of mini-channel heat sink with high heat dissipation rate and the fluid flow patterns inside mini-channels for integrating secondary channel (or interconnector). A novel shape, rectangular fin with rounded ends, mini-channel heat sink was proposed to compare with the thermal performance of rectangular finned and oblique finned mini-channel heat sink. In this study, hydrodynamic characteristics of water as coolant was considered in the single-phase regime, and the flow was considered under laminar flow conditions at Reynolds numbers range of 150 to 1050 with a constant heat flux of 200 KW/m2 at the bottom surface of the mini-channel heat sink. Thereafter, a Performance Evaluating Criteria (PEC) was implemented for all cases to compare with the conventional mini-channel heat sink. The results showed that the overall Nu number for newly proposed rectangular fin with rounded ends shape mini-channel heat sink increases slightly with Re number when compared with the conventional mini-channel heat sink. The slight increment of Nu number was recorded at Re = 1050 for the newly proposed mini-channel heat sink up to ∼8% as compared to the conventional parallel flow mini-channel heat sink.
Analysis of Liner Deformation Behaviour in Transtibial Prosthesis
Authors: Regalla Srinivasa Prakash , Prashant Kirange Piyush , Dhake Harshal Vinayak , Shrivastava Prakash Narayan
Published: January 2022

The problems associated with the prostheses for transtibial amputees are related mainly to fit and comfort. There has been a steady effort to improve the below-knee prosthesis’s wearability, stability, and durability. The liner in the below-knee prosthesis plays a crucial role in ensuring these quality characteristics. Isotropic liner material either acts hard and results in discomfort or deforms too much and results in eventual loosening of the prosthetic socket. The material hyper-elastic behavior and thickness are both critical in the design of the liner with optimum comfort. A generalized deformation model considers the interaction of the socket, liner, muscle, and tissue becomes cumbersome. In the literature, numerous hyper-elastic models have been applied. However, studies on the suitability and application of hyper-elastic materials for liner material have not been sufficiently carried out. In this paper, the usefulness of liner materials in terms of their ability to allow sufficient elastic deformation in the normal direction for the cushioning effect while undergoing limited shear deformation has been investigated. The hyper-elastic liner and rigid socket pair have been idealized as adhesively bonded flat layers of suitable thicknesses subjected to various normal and shear load combinations. The deformations for a normal load and varied range of shear loads have been compared to conclude on the best-suited material model. The low shear deformation observed for all three liner materials implies that the shear loading will not affect the adhesive bond between the liner and socket and hence will not cause loosening with prolonged usage of the prosthetics. The deformation observed was maximum with Ogden 3-parameter hyper-elastic model, whereas it was least in the case when Mooney Rivlin 3-parameter hyper-elastic model. The results obtained for the Mooney-Rivlin 3-parameter model and Neo-Hookean model are very close to each other.
Using a Modified Frequency Domain Method Coupled to a Physics Based Model With Non-Uniform Heat Generation to Evaluate the Entropy of Reaction in a Li[NixCoyMnz]O2/Graphite Lithium Ion Battery
Authors: Hammond Jonathan , McCreary Chase , Abbasalinejad Armin , Kim Sun Ung
Published: January 2022

The entropy of reaction is necessary to estimate how much heat could be generated by a battery. Calculating heat generation is critical both for safety reasons and to improve the longevity and performance of the cell. Traditional methods of measuring the entropy of reaction are painstakingly slow and require environmental control machinery. Previously we modified a frequency domain method using a physics-based model and demonstrated that the entropy could be measured at a significantly faster pace. In this paper, we measured the entropy of reaction of a customized pouch cell with two different methods: the modified frequency domain method and the traditional method. Results from the new method were compared against measurements taken on coin cells of the same chemistry using a traditional method. The model validation shows a high degree of accuracy, roughly 50 μV/K, using the new method.
Predicting Steam-Gasification Output Using Artificial Neural Networks
Authors: Shi Yunye , Yepes Maya Diego , Ratner Albert
Published: January 2022

Steam gasification has been identified to be one of the most important technologies to produce syngas for biofuel synthesis, due to the high H2 concentration it can reach, which is significantly higher compared with conventional air gasification processes. Double-stage downdraft gasification has proven to be efficient with a secondary steam injection. Various kinds of models, including computational fluid dynamics (CFD), thermo-equilibrium, kinetic rate, and artificial neural network (ANN) have been developed for studying these processes.

Equilibrium models assume of chemical reaction equilibrium, in which the transfer phenomenon and the reaction kinetics of primary reactions are considered. In CFD models, the mass, momentum, and energy equations are solved simultaneously along the consideration of the gasifier design to predict parameters such as temperature or species concentrations. To overcome the limitations posed by these models, artificial intelligence tools such as ANNs are reliable for the prediction of nonlinear system data. The application of ANN in gasification processes have been reported by several researchers. ANN based models have been developed for predicting syngas yields and gas composition in air gasification systems. However, to the author’s knowledge, no study has focused in the prediction, using ANN, of a double-stage steam gasification system.

In the current study, the effect of different temperatures along the gasification process (T0-T7), equivalence ratio, and steam-to-air ratio were studied in an artificial neural network model to predict the gas composition (CO, CH4, and H2) and the lower heating value (LHV) of the syngas. Miscanthus grass is selected as the fuel. The ultimate analysis of the fuel is excluded in the input because the insignificant impact on syngas composition especially H2 production. Feed forward back propagation (FFBP) neural networks were employed for the training of the networks. Then the model with optimal parameters were selected to test against experimental data for validation purposes. Further, the unused data are tested for model accuracy. It was observed that the developed models are able to predict the CO, CH4, H2, and LHV with good accuracy when comparing with experimental data. The FFBP showed excellent performance. A higher coefficient of determination (R2) and lower mean square error (MSE) is achieved by FFBP. The results obtained indicate that ANNs are powerful tools to facilitate system design, operation and control of double-stage downdraft gasifiers with various operating conditions. Utilizing ANN models, one can predict reasonable output parameters without unnecessary failure.
Power Estimation of an Experimental Ocean Current Turbine Based on the Conformal Mapping and Blade Element Momentum Theory
Authors: Sadeqi S. , Xiros N. , Aktosun E. , VanZwieten J. , Sultan C. , Ioup J. , Rouhi S.
Published: January 2022

Conformal mapping techniques have been used in many applications in the two-dimensional environments of engineering and physics, especially in the two-dimensional incompressible flow field that was introduced by Prandtl and Tietjens. These methods show reasonable results in the case of comprehensive analysis of the local coefficients of complex airfoils. The mathematical form of conformal mapping always locally preserves angles of the complex functions but it may change the length of the complex model. This research is based on the design of turbine blades as hydrofoils divided into different individual hydrofoils with decreasing thickness from root to tip. The geometric shapes of these hydrofoils come from the original FX77W121 airfoil shape and from interpolating between the FX77W121, FX77W153, and FX77W258 airfoil shapes. The last three digits of this airfoil family approximate the thickness ratio times 1000 (FX77153 => 15.3 % thickness ratio). Of the different airfoil shapes specified for the optimal rotor, there are 23 unique shapes.[15, 16, 17, 18, 19, 20, 21, 22, 24, 25, 28] This study describes the advantage of using at least one complex variable technique of transformation conformal mapping in two dimensions.

Conformal mapping techniques are used to form a database for sectional lift and drag coefficients based on turbine blade design to be used in Blade Element Momentum (BEM) theory to predict the performance of a three bladed single rotor horizontal axis ocean current turbine (1.6-meter diameter) by considering the characteristics of the sea-water. In addition, by considering the fact that in the real ocean, the underwater ocean current turbines encounter different velocities, the maximum brake power will be investigated for different incoming current velocities. The conformal mapping technique is used to calculate the local lift coefficients of different hydrofoils with respect to different angles of attack: −180 ≤ AOA ≤ +180. These results will be compared to those from other methods obtained recently by our research group. This method considers the potential flow analysis module that follows a higher-order panel method based on the geometric properties of each hydrofoil cross section. The velocity and pressure fields are obtained directly by the applications of Bernoulli’s principle, then the lift coefficients are calculated from the results of the integration of the pressure field along the hydrofoil surface for any angle of attack. Ultimately, the results of this research will be used for further investigation of the design and construction of a small-scale experimental ocean current turbine to be tested in the towing tank at the University of New Orleans.
Transient Two-Phase Flow Pressure Drop During Droplet Emergence and Growth in Gas Flow Channels
Authors: Mortazavi Mehdi , Watkins Cade , Murchie Colin
Published: January 2022

The water produced during the operation of proton exchange membrane fuel cells can pass the electrode and emerge from the surface of the gas diffusion layer (GDL), forming liquid-gas two-phase flow in the channel. It is of great importance to be able to precisely quantify the water content in the channel. One method to do so is to measure the pressure drop in the channel and correlate the two-phase flow pressure drop to the accumulated water in the channel. The topic of two-phase flow pressure drop in PEM fuel cell flow channels is investigated in the literature. However, the main focus has been put on the pressure drop in the steady operating condition of the cell. The current study evaluates variation of the pressure drop in the channel while a droplet is emerged from the surface of the GDL. This corresponds to the early operation of the cell. The pressure drop data during droplet growth was acquired in a transparent ex-situ test section while images of droplets were taken in real time with a highspeed camera. The combination of pressure drop data and the size of the droplet obtained from images were used to obtain the drag force applied on the growing droplet. Experimental results showed that the droplet detachment height decreased from 1.54 mm to 1.14 when the superficial gas velocity increased from 4.17 m/s to 10.76 m/s. This decrease in the droplet detachment size reduced the drag force needed to detach the droplet by overcoming the pinning forces. For the same increase in the superficial gas velocity, the drag force decreased for around 50%. Moreover, evaluation of droplet profiles at 10.76 m/s superficial gas velocity indicated that contact line expanded in the downstream of the droplet and the advancing contact angle increased for around 40° from droplet emergence to its detachment.
Mechanical Design and Development of a Suborbital Payload for Real-Time Data Acquisition and Structural Health Monitoring
Authors: Cvetic-Thomas Dillon , Tattershall Amy , Jackson Eli , Robergs Dane , Nwokocha Funmilola , Zagrai Andrei
Published: January 2022

Real-time data acquisition and structural health monitoring (SHM) are in any aerospace black box. To facilitate the development of such technologies, test payload architectures must be designed to safely deliver experimental components to the environments they are expected to perform in. The purpose of this project was to design, analyze, assemble, and launch a payload enclosure system as part of a collaborative experiment involving SHM by New Mexico Tech and distributed data acquisition by Immortal Data Inc. Particular attention was given to the integration of the hardware pertaining to the SHM experiment. This experiment monitors the condition of a cantilever beam throughout the flight using an electro-mechanical impedance method. The enclosure mount was designed to tolerate the vibrational, thermal, and g-loads experience in suborbital flight. With these criteria in mind, ULTEM 1010, an industrial strength 3D printing material, was chosen due to its significant yield strength and low density when compared to other 3D printing material and aluminum candidates. To determine whether or not the tolerances and requirements are sufficiently met, finite element analysis of the payload structure was performed in COMSOL Multiphysics and Solidworks. Stresses due to acceleration loads, de-spinning events, and ground impact were evaluated and safety factors were determined. To enable the electro-mechanical impedance diagnostics, a thin piezoelectric wafer sensor was bonded to the beam and connected to a miniaturized impedance analyzer. This system allowed for local storage of the electro-mechanical impedance data. Validation of this experimental setup was performed in laboratory conditions in which the impedance of the beam was measured in several frequency bands. Based on dynamic characteristics of the beam, low frequency bandwidth was selected for impedance analysis. Numerical studies confirm the enclosure design’s validity and the possibility of electro-mechanical impedance diagnostics of the payload.
Design of a Robotic Vehicle for ASME Student Design Competition 2021
Authors: Kochanczyk Wojciech , Chauhan Vedang
Published: January 2022

Robotics is a very active and diverse field with new applications found daily for emerging designs. This year ASME SDC emphasizes one such application with small RC robotic vehicles. These vehicles are primarily cargo carriers with the ability to harness wind and solar renewable energy sources to recharge their limited battery. Analog to modern electric battery-powered cars the robot utilizes a single AAA battery which was the biggest challenge of the competition. To satisfy all the requirements posed by the competition, a brand new vehicle platform was developed including both wind and solar charging capabilities. As part of the development process a new drive train, control system, wind turbine, and robot frame was developed. For performance maximization, all outsourced, as well as custom-designed components, were extensively researched and tested. Using test data and CAD software the final design was created including all the components selected during testing. This produced a successful prototype satisfying all competition requirements and being accepted to take part in SDC 2021. The maximum score achieved by the robot reached 0.4488 points using the given scoring matrix, however, it did not qualify for the final rounds of the competition. This project indicated several ideas that may improve the performance of small robots, such as the effective use of solar panels, the creation of systems with low power requirements, as well as the use of RC toys to develop more complex robotic vehicles.