bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultrasonic Phased Array Technique for Defect Detection and Sizing in Heavy-Walled Cast Components
Authors: Hossain Md Shahjahan , Krenek Russell , Taheri Hossein , Dababneh Fadwa 
Published: February 2021

Abstract
Cast metal parts are extensively found in many engineering products such as pump casing and engines. Thermal effects exhibited during metal casting processes, such as solidification can generate defects in the cast components. Effective nondestructive testing (NDT) for detection and sizing of defects in cast parts prevents extra cost and time associated with repair and maintenance. Surface-breaking cracks and porosity are among the common types of defects in large cast components. There are several limitations in using conventional NDT methods for as built cast parts due to surface conditions, coarse-grain structure, and characteristics of potential defects. Ultrasonic adaptive imaging based on the Phased Array Ultrasonic Testing (PAUT) technology is proposed for coarse-grain heavy-walled cast material inspection. The capability of aperture focusing in PAUT provides the opportunity for better imaging results. A comprehensive understanding about the ultrasonic beam focusing and the selection of an appropriate transducer and wedges is necessary for successful defect characterization. Cast aluminum and iron samples having on-purpose made defects were successfully inspected using the PAUT. Unlike conventional techniques, the results indicated that the PAUT is a promising method for inspecting as-built cast parts with rough surface finish conditions. The proposed method helps to decrease the inspection time, machining requirements, and preparation costs. Moreover, the enhanced defect sizing approach provides useful information for repair and maintenance decision making such as amount of material grinding and post-welding procedure.
Bioinspired Monolithically Designed Compliant Swimming Robots
Authors: Hooper Joshua , Houghton Andy , Tekes Ayse 
Published: February 2021

Abstract
As technology advances and enables us to design and realize complex systems using new materials and manufacturing methods, biologically inspired robots in every aspect of engineering have attracted much attention in the last few decades. This paper presents the design and motion analysis of monolithically designed two compliant swimming robots that are actuated and controlled by single motor. Each design incorporates large deflecting compliant members and rigid levers to transfer the input torque to the different parts on the mechanism. While the first design integrates flexible tail to perform swimming motion, the second design adopts snapping type motion for the same action. Both mechanisms are 3D printed and tested for forward motion. The first robot has a constant speed of 0.68 BL/s while the second has an average speed of 0.6 BL/s. Kinematic model using pseudo rigid body modeling (PRBM) is derived to calculate the load-deflection curves of the flexible tail for Design I, finite element analysis for deflection analysis are performed for Design II.
A Model for Sustainable Orthopedic Care in Low and Middle Income Countries
Authors: Gillard Joel , Smith Terry 
Published: February 2021

Abstract
This paper describes a scalable and sustainable patient care model for low and middle-income countries (LMICs) that can improve the standard of care for hospitals with scarce resources and an ever growing backlog of patients. SIGN Fracture Care International (SIGN), a non-profit, humanitarian medical device organization, has developed technical solutions over the last 20 years, to address the yearly increasing number of patients affected by upper and lower extremity trauma, using a three-pronged approach. The model includes effective training of in-country local surgeons on current orthopaedic techniques; providing an on-going supply of appropriately designed surgical implants and instruments manufactured to ISO 13485 and FDA standards; and evaluating patient outcomes until healing occurs to validate the model is truly benefiting patients and the hospital throughput. By providing equal access to technology, knowledge, and timely feedback, LMIC surgeons can provide vital orthopedic care to their local communities and sustainably respond to the daily trauma cases they encounter and enable patients to return to work, school, keep families on the path out of poverty, and improve the lives of future generations. The model is describe in detail in the hopes that other entities can utilize the principles for additional healthcare specialties around the world.
Computational Analysis of the Dynamics Flow in the Duct System of an Continuous Positive Airways Pressure Device
Authors: Vuong Tung Xuan , Al-Jumaily Ahmed , Paxton Robert 
Published: February 2021

Abstract
In this paper, 3-D duct models of Continuous Positive Airway Pressure (CPAP) device are developed to investigate the internal airflow behaviours and to identify potential noise source locations. The Computational Aeroacoustics (CAA) with a hybrid approach is conducted in the ANSYS software environment. CFD simulations were used to investigate the internal flow behaviours of the duct systems. The predicted results have shown the internal flow characteristics as circulation and separation behaviours. Those behaviours were found at several locations such as 90-degree corners, restricted cross-sectional areas, etc. High levels of turbulent energy are also found in those locations indicated they are likely to have a high level of noise. Further investigation to predict the noise generated from the duct system to validate the findings in CFD simulations. The results showed that there is a high level of noise generated at the identified locations in the CFD simulations. The noise experiments were also conducted to compare with the predicted noise results. It was found the predicted models can be used to evaluate the flow behaviours inside the duct system.
In summary, the CAA with a hybrid approach is used to investigate the internal flow behaviours and the potential noise source locations of the duct systems in the studied CPAP device. The predicted results have explained and identified some potential noise source locations. These findings will be used as guidelines to optimize the internal flow and therefore improve the noise generated from ducts. The broadband noise source models are potential tools that can be used to determine the loudness at the source locations in the early product development process for reducing noise level and better sound quality as well as a cost-effective tool for noise prediction.
Energy Absorption Characteristics of Axially Compressed Double Wall Foam Filled and Empty Square Tubes
Authors: Prakash Raghu V. , Toshniwal Sanjay 
Published: February 2021

Abstract
Occupant safety has become increasingly important in the recent times. At the instance of an accident or collision, structures with high energy absorption can provide better occupant safety. Thin-walled tubes are widely used as energy absorbers in automobiles and other structures. In the present work, crashworthiness characteristics of double wall empty and double wall foam filled tubes are investigated. Thin wall extruded aluminum square tubes are used in this study. Polymer foam of three different densities, viz., 40 kg/m3, 80 kg/m3, 140 kg/m3 was used as filler material between the two tubes to fabricate a double wall foam filled tube. Both parallel and diamond configurations were considered for double walled empty and foam filled configurations. All the specimens were compressed at a displacement rate of 100 mm/min. Crushing of different configurations was numerically analyzed using nonlinear finite element tool LS-Dyna®. In double wall empty configuration, diamond arrangement absorbed more energy compared to parallel due to the interaction between inner and outer tubes. Results indicate that energy absorption increases with the filling of foam. Compared to double wall tubes, the maximum increase in energy absorption of ∼ 50% is observed in foam filled tubes. Using Computed Tomography (CT) scan of specimens, it is observed that foam filling alters the crushing behavior of the inner and outer tubes.
XFEM Fracture Analysis of 2-D Plastically Graded Domain With Thermo-Mechanical J-Integral
Authors: Gajjar Margi , Pathak Himanshu 
Published: February 2021

Abstract
Many engineering components fail in the presence of service loads like thermal residual stresses and thermomechanical loading. An accurate evaluation of the fracture parameter (J-integral) at the crack tip is essential for the safe design of structures.
In this work, a novel computational method called the Extended Finite Element Method (XFEM) has been implemented to analyze the plastically graded material (PGM) subjected to thermal and thermo-mechanical loading. For crack discontinuity modeling, a partition of unity enrichment concept can be employed with additional mathematical functions like Heaviside and branch enrichment for crack discontinuity and stress field gradient, respectively. The modeling of the stressstrain relationship of material has been done using the Ramberg-Osgood material model. The isotropic hardening and Von-Mises yield criteria have been considered to check the plasticity condition. The variation in plasticity properties for PGM has been modeled by exponential law. Further, the nonlinear discrete equation has been numerically solved using a Newton-Rhapson iterative scheme.
Less Conservative Stability Constraint for Data-Based Feedback Tuning
Authors: Huang Weicai , Yang Kaiming , Zhu Yu , Lu Sen , Li Min 
Published: February 2021

Abstract
It is necessary to keep the closed-loop system stable in data-driven feedback tuning. A widely-used strategy is using stability criterions as the constraint while parameter updating. In this strategy, the conservatism of the stability constraint has great influence on the achievable convergence performance. In this paper, a less conservative stability constraint is proposed to improve the convergence rate of data-driven feedback tuning methods. Specifically, the proposed stability constraint is developed based on small gain theorem (SGT). The conservatism is reduced through extension of SGT and further reduced using the properties of H∞ norm. Besides, an unbiased data-driven estimation method of H∞ norm is employed to estimate the proposed stability constraint accurately. Simulations are conducted to test the performance of the proposed stability constraint. The results demonstrate that the proposed stability constraint is less conservative and contributes to higher convergence rate.
Nanomechanical Characterization of Additive Manufactured GRCop-42 Alloy Developed by Directed Energy Deposition Methods
Authors: Suresh Trupti , Landes Scott , Letcher Todd , Prasad Anamika , Gradl Paul , Ellis David 
Published: February 2021

Abstract
Propulsion applications such as combustion chambers and nozzles for liquid rocket engines require the use of unique materials with superior mechanical and thermal properties. GRCop-42 (Cu-4 wt.% Cr-2 wt.% Nb) is one such candidate material developed by NASA and is now being manufactured using additive manufacturing (AM) techniques. AM offers a unique processing environment different from traditional metal fabrication processes. This study characterized the mechanical and structural properties of as-deposited and heat-treated GRCop-42 manufactured with Blown Powder Directed Energy Deposition (BPD) based on preliminary testing. The materials were characterized using several techniques including surface profiling by laser microscopy, mechanical stiffness by instrumented indentation, crystal structure, residual stress measurements using XRD and residual XRD, and chemical composition and microstructural evaluation using SEM with EBSD. The results of the study are compared using the BPD techniques for samples in the as-deposited and heat-treated conditions.
Wind Harvesting on Mars: Study and Approach
Authors: Qomsiya Mohanad , Fletcher Robert W. 
Published: February 2021

Abstract
Sustainable energy utilization on Mars is fundamental for the success of habitation on Mars. The two sustainable energy sources for In-Situ Resource Utilization (ISRU) with the highest potential for implementation on Mars are solar and wind. Unfortunately, the former cannot provide a reliable continuous source of energy for multiple reasons. Accordingly, wind energy is presented as a viable solution, or as a strong potential complement to solar energy.
The authors investigate different sites on Mars by evaluating the available wind resources to select the most feasible location in terms of energy yield and other critical habitability criteria. This work is conducted by applying the General Circulation Model (GCM) simulation, this particular analysis of wind harvesting feasibility on Mars will be studied by employing the Mars Climate Database (MCD) model.
In addition, this novel research provides a systematic approach for future energy harvesting projects on Mars. Moreover, it evaluates different potential wind turbine design concepts applicable for the Martian ISRU. The results of this research lay the foundation for future energy utilization necessary for habitation to thrive, as well as it will be a key for future exploration missions. Ultimately, this will enrich our understanding of wind turbine systems.
Bayesian Information Fusion of Multmodality Nondestructive Measurements for Probabilistic Mechanical Property Estimation
Authors: Chen Jie , Liu Yongming 
Published: February 2021

Abstract
Missing data occur when no data value is available for the variable in an observation. In this research, Bayesian data augmentation method is adopted and implemented for prediction with missing data. The data augmentation process is conducted through Bayesian inference with missing data assuming the multivariate normal distribution. Gibbs sampling is used to draw posterior simulations of the joint distribution of unknown parameters and unobserved quantities. The missing elements of the data are sampled conditional on the observed elements. The distribution of model parameters and variables with missing data can be obtained for reliability analysis. Two examples are given to illustrate the engineering application of Bayesian inference with missing data. The first example is to predict the yield strength of aging pipeline by fusing the incomplete surface information with missing data. The predictive performance is compared among direct surface indentation technique, linear regression with complete data and Bayesian inference with missing data. The second example is to predict the fatigue life of corroded steel reinforcing bar from the incomplete input dataset. The predicted fatigue lives are compared with experimental data. Both examples demonstrate that the Bayesian method can deal with missing data problem properly and show good predictive performance.
Effect of Freeze Pipe Eccentricity in Artificial Ground Freezing Applications
Authors: Zueter Ahmad F. , Xu Minghan , Alzoubi Mahmoud A. , Sasmito Agus P. 
Published: February 2021

Abstract
Building concentric tubes is one of biggest practical challenges in the construction of freeze-pipes of artificial ground freezing (AGF) applications for deep underground mines. In this study, the influence of tubes eccentricity on phase-front expansion (i.e., expansion of the frozen body) and energy consumption of AGF systems is analyzed. A 1+1D semi-conjugate model that solves two-phase transient energy conservation equation is derived. The model is firstly validated against experimental data and then verified with a fully-conjugate model from the literature. After that, the model is extended to a field scale of typical deep underground mines to study freeze-pipe eccentricity. The results show that an eccentric freeze pipe can reduce the phase-front expansion by around 25%, as compared with a concentric one. Also, the geometrical profile of the phase-front is significantly influenced by the freeze-pipe eccentricity. Furthermore, in the passive zone, where AGF coolants are isolated from the ground to reduce energy consumption, freeze pipe eccentricity can increase the coolant heat gain by 10%. This percentage can increase up to 200% if radiation heat transfer is minimized.
Numerical Interlaminar Shear Damage Analysis of Fiber Reinforced Composites Improved by ZnO Nanowires
Authors: Marashizadeh Parisa , Abshirini Mohammad , Saha Mrinal , Liu Yingtao 
Published: February 2021

Abstract
In this study, the damage analysis of hybrid carbon fiber reinforced polymer (CFRP) composited with vertically aligned zinc oxide (ZnO) nanowires is investigated numerically. The effect of growing nanowires on improving the interlaminar shear strength (ILSS) of the hybrid structures is explored. The multi-scale model developed to make a bridge between the materials with different length scales available in the hybrid structures, including micro-scale, meso-scale, and macros-scale. The vertically aligned ZnO nanowires on the lamina and embedded in the epoxy matrix creates an enhancement layer. The effective material properties of this layer are evaluated at micro-scale by homogenization analysis. The cohesive zone method is employed in the meso-scale to explore the interfacial behavior and delamination (interlaminar damage) between the homogenized stacking layer and the CFRP lamina. Besides, the strain-based failure criterion is implemented at the macro-scale to investigate the progressive damage of fiber and matrix in CFRP plies. This analysis is programmed in user-defined subroutine linked to ABAQUS finite element software. The three-dimensional hybrid composite short beam in the three-point bending load is simulated in ABAQUS Explicit packager, and the ILSS is obtained. The damage behavior of hybrid composite is compared to the bare CFRP beam. The results indicate that aligning nanowires on the plies improves the performance of CFRP composites.
Evaluation of the Mechanical Properties of Repaired Composite Panels Using Resin Re-Infusion Process
Authors: Abd El-Latief Mahmoud E. , Shazly Mostafa , Bahei-El-Din Yehia 
Published: February 2021

Abstract
Glass Fiber Reinforced Plastics (GFRP) have been used in many fields such as aerospace, automotive and wind energy sectors. During their manufacturing processes, some defects such as dry spots and air pockets may develop in impregnated fabric, especially, when metallic inserts are used. To evaluate the interface between parent and repaired parts, an experimental study is performed to investigate its effect on the mechanical properties and structural integrity. To compare the response of the re-infused and intact samples, several tensile and bending tests were performed for uniaxial glass reinforcing fabric with tailored orientation for the interface between the intact and repaired regions. The results showed that for the tensile tests, repaired specimens with interfaces having 90° and 45° orientations w.r.t. loading direction were able to recover 80% and 73%, respectively, from the tensile strength of samples produced by vacuum infusion technique. However, for bending tests, the flexural strength was recovered by almost 90% and 72% for both interfaces, respectively. Based on visual inspection, each type of tested specimen has a typical dominant failure mode. For re-infused samples, the properties of the parent and repaired laminates determine the failure location.
Transient Performance of Heat Pipes Using Nanofluids
Authors: Mahdavi Mahboobe , Faghri Amir 
Published: February 2021

Abstract
In the present works, a comprehensive transient numerical model was developed to evaluate the effect of nanofluid on the transient performance of heat pipes. The numerical model solves for compressible vapor flow, the liquid flow in the wick region, and the energy equations in the vapor, wick and wall. The distinctive feature of the model is that it can uniquely determine the heat pipe operating pressure based on the physical and operating conditions of the system. Three nanoparticle types were considered: Al2O3, CuO, and TiO2. The effects of the concentration of nanoparticles (5%, 10%, 20% and 40%) were investigated on the heat pipe response time, thermal resistance, and pressure drop under various operating conditions. The results showed that the use of nanofluid decreased the response time of the heat pipe by the maximum of 27%. It was also discovered that the thermal resistance decreased significantly with an increase in the volume concentration. A maximum reduction of 84%, 82% and 78% in thermal resistance was obtained for Al2O3, CuO, and TiO2, respectively. In addition, the effect of nanoparticles on the liquid pressure drop highly depends on the nanoparticle type and volume concentration.
Optimization of Nodule and Height Sizes for Mixed Hydrophilic and Hydrophobic Surfaces
Authors: Frymyer Brian , Oztekin Alparslan 
Published: February 2021

Abstract
Patterned surfaces of hydrophobic and hydrophilic materials are considered to sustain dropwise condensation, providing the benefits of both materials and creating a surface with a low energy barrier for nucleation and capable of sustaining dropwise condensation. Surface heights, nodule sizes, and flow rates are evaluated on square-patterned surfaces to maximize mass collection. A thermal model is used to assess surface performance and includes an equivalent thermal resistance for diffusion. Flow rates of 15, 25, 50, and 100 m/s with nodule sizes between 0.1 mm to 3.6 mm are evaluated. Surface heights of 0.25, 0.5, 1, and 2 m are also assessed. For flow rates greater than 50 m/s, turbulent flow optimum nodule size is between 0.2 mm and 0.6 mm. Surfaces greater than 1 m in height at flow rates less than 50 m/s maximize mass with nodule sizes of 1.4 mm and 2 mm.
The Mechanism of Movement and Calculation of Blood Balance in the Flow Channel From the Left Atrium to the End of the Aorta
Authors: Talygin E. , Kiknadze G. , Gorodkov A. 
Published: February 2021

Abstract
Today, there are a lot of works studying the mechanisms of formation and evolution of self-organizing tornado-like jets of viscous fluid. In these works, the exact solution of the Navier-Stokes equation for such a class of flows are obtained, the geometry of the generating surface for that flows is established and the necessary and sufficient conditions for the formation and evolution of such swirling jets are formulated. However, important aspects of the mechanics of such flows remain unclear — the structure of the boundary layer, the shape of streamlines in general form, the structure of such flows under a pulsating flow regime, and others.
After obtaining the exact solution, attempts were made to obtain relations for streamlines in the corresponding projections. However, due to computational complexity, streamlines were constructed only for regions far from the axis of the swirling flow evolution. In this work, an alternative method of calculating streamlines was used, which made it possible to obtain general relations for these lines at each point in space. Expressions for streamlines contain easily computed functions, which simplifies their practical use Based on the expressions for streamlines, expressions were formulated declaring the conservation of the mass of the swirling blood flow from the left atrium to the aorta and the balance of the medium was calculated.
The results of this work are of great theoretical and practical importance. On the one hand, the established expressions for streamlines allow a better study of the mechanisms of formation and evolution of swirling flows in the axial region. On the other hand, obtaining quantitative ratios for the balance of blood in the heart and aorta allows a more accurate study of the mechanics of blood circulation.