bluuebunny/crossref_metadata_2025_split huggingface dataset:
Flow-Induced Vibration and Wake Flow Dynamics Behind a Harbor Seal Whisker Model in Tandem Arrangement With an Upstream Cylinder
Authors: Dulac Sarah , Mousavisani Seyedmohammad , Breault Tabitha Ann , Seyed-Aghazadeh Banafsheh 
Published: January 2022

Abstract
Flow-induced vibrations (FIV) of a flexibly-mounted harbor seal whisker module, allowed to oscillate in the cross-flow direction, placed in tandem arrangement with an upstream circular cylinder is studied, experimentally. The FIV response of the whisker module in terms of amplitudes and frequencies of oscillation are studied for a reduced velocity range of U* = 3.2–24.2, corresponding to a Reynolds number range of Re = 279–2,077. Flow-induced vibration response is studied and characterized for a wide range of separation distances between the upstream cylinder and the whisker module, as well as the angle at which the whisker faces the oncoming flow (angle of attack).
Instantaneous volumetric flow field behind the whisker model was measured using Volumetric Particle Tracking Velocimetry (PTV) data processed by the “Shake The Box” (STB) algorithm that allowed for the time resolved, three dimensional (3D) 3 components (3C) measurement of flow field in the wake of the whisker module. The wake dynamics of the tandem pair of the whisker module and the upstream cylinder were studied at different angles of attack of the whisker module.
Our results show while the whisker module was placed at 0° angle of attack, it did not experience any flow-induced vibration. However, when an upstream cylinder was placed in tandem with the whisker module, the whisker experienced large amplitude oscillations over a wide range of flow velocities. The whisker module picked up the “footprints” left behind the upstream cylinder for center-to center distance up to 25 times the whisker’s diameter. No oscillation was observed when the upstream cylinder was placed at relatively large distance of 50 times the whisker diameter. When the whisker was placed at 90° angle of attack, both for the standalone configuration of the whisker, as well as the tandem arrangement with the upstream cylinder, large amplitude oscillation were observed over a wide, but limited range of reduced velocities. This type of large-amplitude oscillation over a limited range of the flow velocity, while the frequency of oscillation stayed around the natural frequency of the system resembled those classic vortex-induced vibration response observed in the case of an elastically-mounted circular cylinder. Volumetric flow field measurements revealed highly three-dimensional vortex shedding patterns in the wake of the whisker module, which were attributed to the undulatory spanwise structure of the whisker. When the gap size between the upstream cylinder and the downstream whisker module was small, the wake in the gap region was characterized by the presence of two shear layers that were reattached to downstream whisker module. As the gap size increased, well-developed, highly three-dimensional vortical structures were observed in the gap region.
Implementation of 2-DOF Grabber Arm and Computer Vision on Remotely Operated Underwater Vehicle
Authors: Spino Pascal , Matveev Konstantin I. 
Published: January 2022

Abstract
The development and applications of remotely operated and autonomous underwater vehicles have significantly increased in recent years. As these vehicles operate in the harsh underwater environment, demanding requirements for their design usually reflect in a high cost of underwater systems. However, with more readily available inexpensive electronics and powering systems, lower cost developments have been initiated. In the present work, several modifications of a low-cost remotely operated underwater platform are described. One is a construction of a two-degree-of-freedom arm for manipulating underwater objects. The second is an improvement of the propulsion control on the vehicle to allow for gradual variation of thrust forces instead of the original on/off mode. The third enhancement is a computer vision system for identifying underwater objects of interest that is applied for automated steering of the vehicle. Initial tests with these elements in a laboratory tank are presented and discussed. They include (1) autonomous detection of a target and maneuvering towards it, (2) grabbing and moving an object with manual remote control, and (3) the combined test with autonomous identification, grabbing, and moving of a target. The reported developments and test results can help other researchers pursuing low-cost developments of underwater vehicles.
Theoretical Investigation on the Printed Circuit Heat Exchanger (PCHE) Based S-CO2 Brayton Cycle
Authors: Zhu Huaitao , Yuan Han , Xie Gongnan 
Published: January 2022

Abstract
The supercritical CO2 (S-CO2) Brayton cycle is considered to be one of the most promising cycles for the fourth-generation nuclear power system. In this study, the printed circuit heat exchanger (PCHE) is introduced into the S-CO2 Brayton cycle as the recuperator, the thermodynamic performance of S-CO2 Brayton cycle configuring with both Re-heating and Inter-cooling processes are analyzed. To accurately describe the drastic variations of properties in the recuperator, the segmental calculation method combining conventional heat transfer correlation equations is employed in the simulation of the compact printed circuit heat exchanger, and the thermal hydraulic performance prediction model is utilized to estimate the size of the heat exchanger. In addition, one-dimensional radial-flow turbine model is employed to conduct the turbine calculation. With the reactor outlet temperature of 550°C and compressor outlet pressure of 25MPa, the thermal efficiency of the S-CO2 Brayton cycle is 36.12%, and the length of the PCHE is 1.734m. For the basic S-CO2 Brayton cycle configuring with Re-heating and Inter-cooling processes, both cycle layouts can improve the system efficiency, the Re-heating cycle performs better, with the thermal efficiency increases from 36.12% to 38.26% while the length of the PCHE increases from 1.734m to 1.852m. For the Inter-cooled cycle, the secondary compression ratio plays an important role in cycle performance. With a medium compression pressure ratio, the thermal efficiency of the S-CO2 Brayton cycle is reduced to 35.8%, compared with the high compression pressure ratio at 36.14% and low compression pressure ratio at 36.18%. Nevertheless, system complexity and heat exchanger cost of the low/high compression pressure ratio S-CO2 Brayton cycle is not competitive.
Strategies for the Improvement of Research Competences in the Professional Training of Engineers
Authors: Vidal Carlos R. , Gordon Yimy , Barreto Deibys , Fajardo Juan , Fragoso Pedro 
Published: January 2022

Abstract
The objective of this study is proposing strategies to strengthen research competencies needed by engineers in training. An analytical, situation research was conducted in four Engineering programs from a public university located in the municipality of Valledupar, Cesar Department, in Colombia. A Likert-scale questionnaire of 50 items was designed; while a document, review was performed applying a matrix that systematized the information about the study plan. Ten experts and five experts respectively validated the content of the questionnaire and of the matrix. The interpretation of the data evidenced that the greatest deficiencies of students were methodological competencies such as “result analyses”. They lack foundations on the use and interpretation of data, which hinders data processing for disseminating results, conclusions and recommendations in research reports. It is therefore necessary to transform the curriculum, including better teaching, pedagogical and didactic methods.
Probabilistic Estimation of Posture Metrics Using Novel Loadsols
Authors: Huynh Dan , Steckenrider J. Josiah , Freisinger Gregory 
Published: January 2022

Abstract
This paper presents an original technique for estimating human posture metrics using Novel Loadsols®. Under the proposed technique, center of pressure (COP) metrics are derived by combining physics- and data-driven estimates to achieve reasonably high accuracy at relatively low cost. To develop a training set upon which the probabilistic data model was constructed, 79 trials were conducted in which participants stood comfortably still for 30 seconds at a time simultaneously on a force plate and a pair of Loadsols, where the force plate is considered to be the gold-standard of COP measurement. These data were then used to generate Gaussian mixture models (GMMs) of pairwise combinations of force plate and Loadsol metrics. The GMMs can then be conditioned on Loadsol measurements and fused using Bayesian inference. When the training set was re-processed by converting 12 Loadsol metrics into estimated force plate metrics, it was found that the converted metrics matched ground-truth more accurately on average than raw Loadsol metrics. Furthermore, there was improvement in the r2 values of the regression lines after conversion for 75% of the metrics. Given some experiment and algorithm refinement, the proposed probabilistic approach has potential to offer the accuracy of force plate COP estimation at a fraction of the cost.
Mechanical Upgrade and Gait Development of Re-Sizable Quadruped, HARQ
Authors: Hussain Salman , Tatoglu Akin , Sohn Kiwon 
Published: January 2022

Abstract
This paper presents the continued development of HARQ (Human Assistive and Robust Quadruped) which has been designed and built by ART (Assistive Robot Team) in University of Hartford since 2019. To enable the robot to deal with various obstacles with different sizes, HARQ’s mechanical design and building process was focused on the achievement of kinematic adjustability as its main technical design requirement. In this study, the mechanical design changes, which are implemented to increase the robot’s balancing capability and to prevent the slippery between end-effectors and ground, are described first. Based on the changes, the kinematic analysis is also upgraded and various walking trajectories are designed to enable HARQ to locomote with different gaits. To simplify the previous inverse kinematics process which was built based on the numerical method, the analytical equations are newly derived for HARQ. Lastly, the upgraded robot is tested and evaluated in human-centered environments which include both indoor and outdoor task spaces.
Experimental and Computational Studies on Saltation of Metal Powders Used in Laser Powder Bed Fusion Systems for Metal Additive Manufacturing
Authors: Tran-Le Thao , Wang Jiaxuan , Byron Margaret , Lynch Stephen , Kunz Robert 
Published: January 2022

Abstract
The ability of Powder Bed Fusion (PBF) to create complex geometries across a wide range of materials makes PBF a widely used powder-based metal additive manufacturing (AM) process in various industries for advanced applications. However, compared to conventional manufacturing processes, the metal parts printed by PBF exhibit lower surface quality due to soot and spatter particles arising from laser-powder interaction. To minimize spatter and soot generation during the build, PBF systems are equipped with cross-flow nozzles that are designed to flow inert gas across the build platform. It is desired that these gas flow systems have the ability to remove most of the spattered powder from the build chamber, but do not erode the freshly spread layer of powder on the to-be-printed surface to ensure high-quality manufactured parts. The onset of particle bed erosion can be characterized by the critical Shields number. Once the critical Shields number is known for the metal powders and system of interest, the flow of inert gas in the build chamber can be optimized to ensure the build process is efficient and clean.
This work proposes a Shields number-based method for obtaining engineering design guidance for PBF gas flow systems to optimize the spatter removal process. A combined experimental and Computational Fluid Dynamics (CFD) study was performed to provide design guidance for these cross-flow systems. All experiments were conducted using a small, closed-loop wind tunnel, with built-in flexibility, capable of testing a number of cross-flow configurations. A high-speed camera captured the threshold of particle movement at a variety of operating conditions for various metal powders used in metal AM including aluminum alloy AlSi10Mg, nickel-based superalloy Inconel 718, titanium alloy Ti-6Al-4V, steel alloy 4340, and 316L stainless steel. Time-averaged flowfield measurements of the gas flow inside the test section were made using particle tracking velocimetry (PTV) and a hot-wire air flow meter at the same conditions. Using these experimental measurements and attendant CFD simulations, CFD predictions of wall shear stress can be used to calculate the Shields number at the condition of incipient movement as identified experimentally.
Numerical Modeling of a Hybrid Asymmetric Rolling and Bending Process
Authors: Dubey Abhay Kumar , Shahare Harshal Y. , Pesin Alexander , Pustovoytov Denis , Yu Hailiang , Tandon Puneet 
Published: January 2022

Abstract
Aerospace and automobile industries demand bend sheets with different radii of curvature and in some cases, even the sheets of continuously varying radius of curvature are also required by them. Forming of such parts require a flexible manufacturing process to closely control the radius of the curvature being formed. This work proposes a hybrid forming process that combines asymmetric rolling with incremental bending to form bend sheets with improved mechanical properties. In the proposed hybrid process, thin metal sheets are asymmetrically cold rolled and then bend by a punch placed after the rolling mill, in the direction of sheet flow. The work presents the numerical simulation of the hybrid process and explores the relation between the hammering amplitude and its frequency on the radius of curvature. Besides, the significance of different parameters on the bend sheet being formed is also investigated using analysis of variance (ANOVA). The results show that the velocity ratio and hammering amplitude are the paramount factors in the proposed hybrid process, and these parameters greatly influence the radius of the bend. Simulation results also indicate that the radius of bend can be augmented by decreasing velocity ratio, hammering frequency, and effective amplitude.
Identification of the Material Hardening and Failure of an Aluminum Alloy Sheet via a Simple Shear Test
Authors: Luo Qiusha , Yuan Lin , Chen Kelin 
Published: January 2022

Abstract
Numerical simulation of the ductile failure of sheet metals usually requires a hardening response to large strains and a reliable failure criterion. This work investigates the material hardening and shear failure of AA6061-T6 sheet using a newly designed shear specimen. A series of numerical simulations are conducted to investigate the stress and strain states in some critical regions of the specimen, and an optimized geometry is obtained that delays the localized deformation on the edges of the specimen. The newly designed shear specimen is tested using a universal testing machine and the Digital Image Correlation (DIC) technique is adopted to monitor the strain field. The von Mises equivalent strain in the test section reaches 0.79 before the specimen fractures. For comparison, two simple shear tests of AA6061-T6 sheet based on two representative shear specimen designs from the literature are conducted using the same experimental setup. The two shear specimens fail at the strain level between 0.5 and 0.6, lower than the failure strain of 0.79 obtained in ours. This comparison shows the better performance of our newly designed shear specimen in the identification of the shear failure strain of this sheet. The shear stress-strain response of our specimen is also used to establish the material hardening response up to a maximum equivalent strain of 0.56, much higher than the limit strain of 0.09 from the uniaxial tension test, which demonstrates the advantage of using appropriately designed shear specimen in the material hardening identification of sheet metals.
Nonlinear Vibration Correlation and Buckling Analysis of Flat Plates and Shells
Authors: Azzara Rodolfo , Carrera Erasmo , Pagani Alfonso 
Published: January 2022

Abstract
The employment of nondestructive techniques in aerospace industries is rising thanks to advances in technologies and analysis. This part of the aerospace testing industry is essential to design and validate the new structures’ methodology and safety. Therefore, robust and reliable nondestructive methods have been extensively studied for decades in order to reduce safety problems and maintenance cost.
One of the most important and employed nondestructive methods to compute large-scale aerospace structures’ critical buckling load is the Vibration Correlation Technique (VCT). This methodology allows to obtain the buckling load and equivalent boundary conditions by interpolating the natural frequencies of the structures for progressively increasing loadings without considering instabilities. VCT has been successfully investigated and employed for many structures, but it is still under development for composite shell structures.
The present work provides a numerical model for carrying out virtual VCT to predict the buckling load, to characterize the natural frequencies variation with progressive higher loadings, and to provide an efficient means for verifying the experimental VCT results.
The proposed nonlinear methodology is based on the well-established Carrera Unified Formulation (CUF). CUF represents a hierarchical formulation in which the structural model’s order is considered the analysis’s input. According to CUF, any theory is degenerated into generalized kinematics and is compactly handled. By adopting this formulation, the nonlinear governing equations and the relative FE arrays of the two-dimensional (2D) theories are written in terms of Fundamental Nuclei (FNs). FNs represent the basic building blocks of the proposed formulation. In order to investigate far nonlinear regimes, the full Green-Lagrange strain tensor is considered. Furthermore, the geometrical nonlinear equations are written in a total Lagrangian framework and solved with an opportune Newton-Raphson method.
For an assessment of the robustness of the virtual VCT, several flat plate and shell structures are studied and compared with the solutions found in the available VCT literature. The results prove that the proposed approach provides results with an excellent correlation with the experimental ones, allowing to investigate the buckling load and the natural frequencies variation in the nonlinear regime with high reliability.
Humanoid Animatronic Learning Simulator for Medical Interactive Training (H.A.L. S.M.I.T.)
Authors: Lauer Ethan A. , Maxwell James , Cohen Gillian , Rene Christopher , Kiritsis Olivia , Radhakrishnan Pradeep 
Published: January 2022

Abstract
Medical training using manikins is becoming more prominent as it provides a highly realistic and beneficial training experience. But, the technology is expensive for low-budget medical programs, and manikins have limited capacity for complex tasks. This project has attempted to address such gaps by beginning the development of a 3D printed head and neck animatronic prototype, capable of performing complex simulations. The target simulations for the manikin included airway management, level of consciousness testing, and circulatory assessment. Major facial features were designed so that the mechanical systems could exhibit anthropomorphic characteristics. Sensors were integrated into the design, allowing the animatronic to detect and react to changes in the surrounding environment. The subsystems were constructed and tested, however, challenges were faced during full assembly. Despite these challenges, the design demonstrates the potential for a similar application in the medical field.
The Development of a Machine for Macroscale Friction Stir Processing: A Work in Progress
Authors: Emblom William J. , Olayinka Ayotunde , Marcel Jared , Ferrara Joshua , DePaula Scott M. , Espinosa-Perez Maria Fernanda , Wagner Scott W. 
Published: January 2022

Abstract
Friction stir processing has become a popular method for welding, surface treatment, and more recently for producing extrusions such as tubing and cylinders. Currently, the extrusions produced usually have diameters from 6 to 19 millimeters because they are being produced in tooling that must be placed in conventional CNC mills located within university research settings and thus have limited available power as well as limited ability for plunge forces.
The machine described here is purpose built for producing large diameter friction stirred cylinders and tubes that are up to 125mm long and 50mm in diameter. Unlike conventional CNC machines, this machine is designed to accommodate the temperatures generated by the probe rotating against the work piece as well as the higher plunge forces generated by the extrusion processes which can damage the bearings, motor shaft and motor in conventional CNC mills. The need to produce larger friction stir processed parts is important because friction stir processing results in material properties that may be advantageous in parts, may be part of an additive manufacturing process, or may be useful as a preprocessing stage for metal recycling operations which can reduce energy costs and product contamination.
The current paper describes Phase 1 of the project. A-1100 aluminum will be the initial material tested and smaller diameters of harder alloys will be used at some future time. The current phase of the project is nearing completion and consists of the development of the machine frame, open-loop AC motor spindle speed controller, tooling and a method for plunging the probe into the work piece. Phase 2 will consist of implementing feedback control along with process monitoring.
In this paper the design process will be summarized, including forces and temperatures expected during friction stir extrusion and back extrusion. The evolution of the design will be summarized with emphasis on the final design. The current status of the project is the machine has been designed and the major components have been purchased and have been assembled. The speed controller for the 10 HP AC (7.5 kW) motor, the rotating probe plunge system, tooling mounting system, and machine frame have also been incorporated into the machine. The basic functionality of the machine has been demonstrated but the variable frequency drive that controls the probe rotation failed in early tests and is being replaced.
Investigating the Use of Magnetic Actuation for a Self-Contained Functional Tongue Prosthetic
Authors: Vasquez Sarah , Lipkin Thomas , Landry Dana , Currie Jenna , Radhakrishnan Pradeep , Albrecht Dirk , Pahlavan Kaveh 
Published: January 2022

Abstract
Oral cancer can result in the loss of the tongue through surgical removal known as glossectomy. Patients who have undergone this procedure face challenges during speech, mastication, and deglutition. Currently, tongue prosthetics lack functionality and are mainly cosmetic. Many of these prosthetics are made of wax and connected to a retainer, which attaches to the back molars of the patient. The goal of this project was to develop a self-contained mechatronic tongue prosthesis that can fit within the oral cavity and aid in deglutition. Investigations into various techniques and sensors supporting miniaturization were carried out and magnetic actuation was found to be the most promising technique. The development process involved redesigning the silicone cast to house sensors, selecting sensors and components for magnetic actuation, magnetic field quantification and miniaturizing various other electrical components. The tongue prosthesis was tested, and the displacement was comparable to a normal human tongue. Details from literature review, design iterations, simulations, validation processes, manufacturing challenges and conclusions will be discussed in depth in this paper.