bluuebunny/crossref_metadata_2025 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

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

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

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

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

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

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

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

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

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

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

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

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

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.
Tool Path Generation for Free Form Surface Slicing In Additive Manufacturing/Fused Filament Fabrication
Authors: Chaudhry Muhammad Salman , Czekanski Aleksander
Published: January 2022

This study is dedicated to develop 3D printing slicing for more specialised applications. Creation of a physical model is a product of the slicing procedure which results in a stack of 2D planar images. Effects of planar slicing results in stair casing effect and is known to effect the mechanical integrity of the fabricated part. To mitigate such effects we present a preliminary study on free form surface slicing procedure. Surface slicing can compliment current 3D printing to develop more customized solutions in fabrication. Results presented show that the end product yielded is superior than its planar slicing counterpart in two aspects. Firstly, stair casing effect can be avoided and secondly visibly greater degree of visible aesthetics can be achieved. Surface slicing is performed on rectangular patch type geometry. Finally, outcomes of this study has been discussed for further development of surface slicing for more customised applications.
Characterization of Wire-Arc Additively Manufactured (WAAM) of Titanium Alloy (Ti-6Al-4V) for Nanomechanical Properties
Authors: Hossain Md Shahjahan , Pliego Ashley , Lee Jinsun , Taheri Hossein
Published: January 2022

The use of metal additive manufacturing (AM) becomes increasingly popular in many industries. AM can create functional parts with lower cost and lead time than the subtractive manufacturing processes. In AM technology, flaws or defects can be present due to variations in the manufacturing process or quality of raw materials, so AM technologies must still be developed to ensure acceptable and reliable quality of the product. Ensuring the high quality of the AM is crucial for safety in critical applications such as the aerospace industry. Various destructive and nondestructive techniques have been used for testing the AM components and their properties evaluation. The use of various nondestructive testing (NDT) techniques is becoming popular for defect identification and characterization of the parts, and still, more techniques need to be developed for better performance and higher optimization. In this study, wire-arc AM (WAAM) parts as-build and heat-treated components have been characterized for nanomechanical properties and finding possible defects created during the fabrication process. Nanoindentation, surface profilometry, and SEM (Scanning Electron Microscope) were used to characterize various wire-arc additive manufactured Titanium alloy (Ti-6Al-4V) samples. The samples were also being tested for material characteristics at different deposition locations and as-deposited versus heat-treated conditions.
Cell Activity Change After Division Under Wall Shear Stress Field
Authors: Hashimoto Shigehiro , Yonezawa Hiroki , Ono Ryuya
Published: January 2022

Does cell orientation depend on the cell type in the shear stress field? Does that tendency change after the division? In this study, the behavior of each cell after division was tracked by time-lapse microscopic images through 24 hours of culture under a shear stress field. A constant shear stress field was applied to the cells in the Couette flow between the parallel walls: the lower static culture disc and the upper rotating disc. For comparison, four types of cells were used: C2C12 (mouse myoblast), HUVEC (human umbilical vein endothelial cells), 3T3-L1 (mouse adipose progenitor cells), and L929 (mouse fibroblast). The result is as follows. In the wall shear stress field of 1 Pa, HUVEC is oriented parallel to the flow, regardless of the division. In other cell types (C2C12, 3T3-L1, and L929) after division, the deformed cell tends to tilt to the direction parallel to the flow. The experimental results are expected to be applied to engineered tissue technologies.
A Bayesian Machine Learning Framework for Selection of the Strain Gradient Plasticity Multiscale Model
Authors: Tan Jingye , Maupin Kathryn , Shao Shuai , Faghihi Danial
Published: January 2022

A class of sequential multiscale models investigated in this study consists of discrete dislocation dynamics (DDD) simulations and continuum strain gradient plasticity (SGP) models to simulate the size effect in plastic deformation of metallic micropillars. The high-fidelity DDD explicitly simulates the microstructural (dislocation) interactions. These simulations account for the effect of dislocation densities and their spatial distributions on plastic deformation. The continuum SGP captures the size-dependent plasticity in micropillars using two length parameters. The main challenge in predictive DDD-SGP multi-scale modeling is selecting the proper constitutive relations for the SGP model, which is necessitated by the uncertainty in computational prediction due to DDD’s microstructural randomness. This contribution addresses these challenges using a Bayesian learning and model selection framework. A family of SGP models with different fidelities and complexities is constructed using various constitutive relation assumptions. The parameters of the SGP models are then learned from a set of training data furnished by the DDD simulations of micropillars. Bayesian learning allows the assessment of the credibility of plastic deformation prediction by characterizing the microstructural variability and the uncertainty in training data. Additionally, the family of the possible SGP models is subjected to a Bayesian model selection to pick the model that adequately explains the DDD training data. The framework proposed in this study enables learning the physics-based multiscale model from uncertain observational data and determining the optimal computational model for predicting complex physical phenomena, i.e., size effect in plastic deformation of micropillars.
Thermoplastics 3D Printing Using Fused Deposition Modeling on Fabrics
Authors: Blais Maxwell , Tomlinson Scott , Khoda Bashir
Published: January 2022

The creation of large objects by additive manufacturing is something that is desired, but often is unachievable due to the size of the object and capacity of the 3D printer used. To address this issue various techniques on part segmentation have been implemented, including origami, geometric segmentation, and segmentation with manufacturability. However, joining or connecting those segmented or discretized additive manufactured parts can be an issue. In this paper we propose to use fabric as a flexible joint and segment carrier when creating larger objects by additive manufacturing. Specifically, flat simply segmented parts of the desired large object will be additive manufactured on top of a fabric as to adhere the two. Three different fabrics, cotton duck cloth, acrylic-dyed and ripstop, were considered to investigate the interfacial strength with 3D printed PLA. Both treated and untreated fabrics are prepared simultaneously so that parts can be printed on top of them at a predefined spatial location. After the fabrication of segments, adhesion force between the segment and the fabrics are tested with mechanical adhesion tests. We found that untreated cotton duck cloth had an average 78% higher adhesion than other samples. When glue was used to treat fabric before printing a weaker bond between the tri-layer, fabric-glue-PLA sandwich was observed comparative to untreated fabrics. The interfacial strength of 3D printed part printed on fabric can be enhanced by changing print parameters, fiber morphology and fabric properties, and surface modification of fabrics. In this work the fiber morphology and fabric properties show significant impact on the interfacial strength. Adhesion forces desired between fabric and 3D printed part can be tailored per specific large object as needed, per segmentation, using this information. The proposed method can help with the fabrication of multifaceted single objects with localized optimum process parameters which can address the directional anisotropic nature of AM parts and corresponding non-homogeneous performance.
Design of a Fractional-Order Controller for the Large Deep Space Observatory Antenna in Wind Disturbance
Authors: Jiang Jianyu , Wu Bin , Zhou Ting
Published: January 2022

To meet the current and future needs of deep space communication services, some large Deep Space Station antennas had to be built on the existing Deep Space Network sites. The influence of wind disturbance has become a serious problem with the increased size of the antenna. Based on the typical antenna model, a fractional-order controller is designed to improve the pointing accuracy of the antenna in wind disturbance. First, the global stability region of fractional-order proportion integral differential (FOPID) controller for the antenna plant was obtained using the Domain-decomposition (D-decomposition) method, Second, the parameters in the stability region were chosen using a genetic algorithm. Then, the disturbance observer is used to estimate and compensate for the influence of the wind disturbance. Finally, a series of simulations and analyses about this fractional-order control system was conducted, the results show that the fractional-order controller works significantly outperform the traditional proportion integral differential (PID) controller, it achieved a remarkable amelioration in the reduction of overshoot and the capacity of wind disturbance rejection.
Design of Litter Collection Robot for Urban Environment
Authors: Su Jian , Cao Yu , Tang Anqi , Wang Siyuan , Dong Janet
Published: January 2022

Keeping sidewalks clean and tidy is a continuously tough task in modern urban environment, traditional solution of cleaning sidewalk is sanitation workers’ manual sweeping. However, manual work is inefficient, laboring intensive and dirty. Main pollutants on the urban sidewalks are simple litter, they consist of recyclable waste such as paper, cardboard and metal cans, and non-recyclable waste like foam and food residue. Thus, the litter on sidewalks can be cleaned, collected and sorted by robots. This paper will discuss the entire design process of a novel litter collection mobile robot for urban sidewalks, including robot structure, drive system, litter collection mechanisms, and stress analysis and motion simulation. This robot can patrol on the sidewalks in urban environment while collecting and sorting litter along the way.

Currently, for cleaning the road on urban street, motor sweeper vehicles are used. There are no motorized vehicles used to clean the sidewalks. Therefore, this robotic approach will fill the gap, avoiding inefficient and overwhelmed manual work. The robot is designed to adapt various terrains of sidewalks such as brick pavements, cement sidewalks, and asphalt sidewalks. The size of the robot is designed to fit most of sidewalks according to research of sidewalk standards.

The litter collection robot consists of a robust chassis, a driving system, a litter collection system, a sensor system for obstacles avoiding, a navigation system for autonomous control and a vision system for litter sorting. For chassis, based on research on sidewalk size standard, its width is designed less than 80 cm to fit inside the sidewalk and at the same time leave enough space for pedestrians passing robot and conducting normal activities. Its height is designed more than 80cm (including robot arm) to make sure it can be noticed by pedestrians, which will avoid potential safety hazard to pedestrians. The weight of the robot is designed to be light weighted to make the robot easy to carry. Moreover, handles are designed in its structure for the convenience of worker’s carrying. For driving system, a two-wheel driving system is designed to adapt various sidewalks. For litter collection system, a robotic arm with four-finger grippers is designed to pick up litter on the sidewalk, and two standard bins are used to contain recyclable and non-recyclable litter separately. Vision system is designed to detect presence and type of litter, so litter will be placed to different bins accordingly. Navigation system is included to enable the robot patrol along the pre-designed path. By applying abovementioned design, this litter collection robot provides a new autonomous approach for urban sanitation work in collecting and sorting litter on sidewalk.
A Novel Formulation to Predict the Accuracy of Implicit Time Integration Schemes
Authors: Tomar Sanjay Singh , Upadhyay C. S.
Published: January 2022

The article presents a novel approach to re-pose the temporal approximation problem as a recursive scheme in terms of displacement and velocity. The recursion matrix is used to obtain the numerical approximation induced amplitude magnification and frequency dilation. From the amplitude magnification term, expressed as a function of the time-step size, one can easily deduce the stability of the method. Similarly, the frequency dilation term can be used to check the accuracy of the numerical scheme. For each time-approximation scheme, a critical parameter (θ = ωΔt) can be identified to guarantee stability and accuracy of the numerical scheme. The performance of classical time-marching schemes, e.g., Newmark scheme, and other single-step schemes is analyzed. Further, a family of Hermite polynomials-based time-approximation methodology is proposed, that can guarantee any desired higher rate of temporal approximation. A residual norm based a-posteriori error estimator has been proposed to investigate the error in the solution. Sample problems have been solved to demonstrate the effectiveness of the current approach.
Attribute-Wise Value of Information in Engineering Systems: A Simulation-Based Study
Authors: Pandey Vijitashwa , Herrmann Jeffrey W.
Published: January 2022

Many engineering decisions involve uncertainty and require tradeoffs between multiple attributes. Often it is possible to reduce or eliminate uncertainty through data collection, or analysis, or both. Although it generally leads to better outcomes, reducing uncertainty may increase cost. This metadecision of whether to reduce the uncertainty at a given cost is undertaken in the form of Value of Information (VOI) studies. Previous work has considered value of information in singleattribute cases, however, studies of the more challenging multiattribute case are less common. Multiattribute problems can have numerous uncertain variables across alternatives, not all of them easily measurable in money amounts, which makes the VOI analysis more complicated. This paper presents a simulation-based approach for calculating and interpreting the VOI in generic multiattribute decision problems and describes a simulation study that we conducted to explore how the decision problem parameters affect the VOI. The relationship between the VOI and the gain in expected utility (utility-gain) that will result from new information is also discussed. This relationship is not simple and yields some expected as well as counterintuitive results. For example, our results suggest that non-linearity of the utility functions may lead to different VoI calculation for the same utility-gain, depending on the relative position of the alternatives. Finally, this paper discusses the sensitivity of the utility from the decision as a function of decision problem parameters and shows that the magnitude of change in VoI can be predicted from these sensitivities. A vehicle alignment problem in an automotive assembly line is presented to demonstrate the approach. The results show that VoI calculation is a challenging problem that is very much contingent on the parameters of the problem. Our results provide insights into the benefits of different ways to evaluate the value of information in multiattribute problems.
Numerical Simulation of Electrified Liquid Jets Using a Geometrical VoF Method
Authors: Cândido Sílvio , Páscoa José C.
Published: January 2022

The stretch of interfacial flows due to the external application of an electric field has considerable importance in several applications. These range from engineering nanofibres to propulsion, the electrified jets bring us an outstanding technique to perform the emission of microdroplets. The present investigation concerns the resolution of interfacial electrohydrodynamic flows from a numerical standpoint using computational fluid dynamics. The reduced form of the Maxwell equations, for an electrostatic field, and a transport equation for the electric charges are coupled to the standard interFoam solvers on OpenFOAM, which resolves an immiscible two-phase flow. A laminar condition is assumed for the flow thus the laminar incompressible Navier-Stokes’s equations are used to compute the hydrodynamic behavior of the flow and, associated with them, electrically induced body forces are incorporated into the hydrodynamic momentum equation. The Maxwell Stress Tensor (MST) describes electrical surface forces acting on the liquid, making it possible to incorporate that effect on the momentum equation. A new efficient geometric Volume-of-Fluid (VoF) method for general meshes, called isoAdvector, was implemented in OpenFOAM, as a substitute for the Multidimensional Universal Limiter for Explicit Solution (MULES). The open literature on the subject presents quantitative benchmarks that demonstrated a significant improvement in the quality with which we can compute sharper interfaces on immiscible two-phase flows (Gamet, L. et al. 2020). Following this approach, we present here an application of that method to the simulation of the breakup of electrified liquids jets. To validate the implementation of the electric field equations, the order of the accuracy of the spatial and time discretization is herein computed. The validation of the discretization of the electric field equations is accomplished with a planar test case that is considered a benchmark test for this class of flows. The test case showed good accuracy on the resolution of the electric potential and electric field having lesser than 0.1% of difference against the theoretical solution. The code is then applied to a Taylor cone jet. This type of jets is at the base of the Electro-hydrodynamic sprays (EHDS) physics. These latter operate by a potential difference between a conductive liquid, usually on the tip of a needle, and an extractor electrode. The numerical model shows a remarkable accuracy on the prediction of the charged droplet size.
Multi-Objective Model-Based Optimization of Pilot Decision Making for Urban Air Mobility
Authors: Holowsko Nicholas , McComb Christopher
Published: January 2022

The emergence of an Urban Air Mobility (UAM) market utilizing fleets of vertical takeoff and land (VTOL) aircraft has the potential to shorten commutes, alleviate traffic congestion, and transform the way people interact with cities. Both industry and academic effort has been aimed towards predicting and simulating fleet activity for the purpose of informing vehicle design decisions and infrastructure planning activities. However, little effort has been targeted at analyzing aircraft fleet performance and sensitivity to pilot decision making, infrastructure availability, and changing vehicle characteristics. In this work, we utilize an existing proprietary, industry developed, discrete-event simulation tool that calculates air vehicle fleet performance with user specified vehicle and demand parameters. Building on this simulation, we then apply an optimization and sensitivity analysis, identifying the relative importance of different vehicle parameters, network attributes, decision making policies, and demand characteristics as they ultimately relate to objective functions that aim to maximize vehicle utilization and minimize the number of deadhead trips. The result of this analysis will inform critical requirements of the UAM market and highlight the importance of effective vehicle scheduling in a UAM scenario.
Insider Attack Scenario Assessment Framework
Authors: Song Jinwoo , He Xinyu , Moon Young
Published: January 2022

Cyber Manufacturing Systems (CMS) brings improvements to the manufacturing system and offers an information-transparent environment. Although CMS’s enhanced system brings many advantages to its manufacturing process, it is at a higher risk of security breach ironically due to its accessibility and connectivity. Therefore, implementing CMS without adequate security measures will make the system vulnerable to intruders including insiders. To identify insider threats, a risk assessment-based framework has been explored by many researchers in the information security community. however, less work has been done to analyze CMS’s vulnerabilities. Therefore, an Insider Attack Scenario Assessment Framework (IASAF) is proposed in this paper. IASAF is developed to detect the system’s security vulnerabilities and evaluate the insider attack scenarios by using five domains including: actor, preparation, implementation, consequence, and recovery. To validate and demonstrate the effectiveness of the framework, a testbed was used to study a case.
Improvement in Photosensitivity of Dumbbell-Shaped Graphene Nanoribbon Structures by Using Asymmetric Metallization Technique
Authors: Goundar Jowesh Avisheik , Xiangyu Qiao , Suzuki Ken , Miura Hideo
Published: January 2022

The existence of Schottky barrier between the semiconductive graphene nanoribbon (GNR) and the metallic electrodes at its both ends causes a major hurdle in the development of GNR based devices. Here, a dumbbell-shape GNR structure was proposed to solve the problem. This structure consisted of a semiconductive GNR and wide metallic GNR at both ends. The ohmic contact between the wide metallic GNR and metallic electrode was easily achieved. Furthermore, an effective mechanism to enhance electronic band properties of the dumbbell-shape GNR structure by using asymmetric metallization technique is employed. To achieve this, two different metallic electrodes were introduced, Platinum (Pt) and Titanium (Ti), at each end of the GNR channel to break the symmetry in the Schottky barrier at both ends. The asymmetric difference in the Schottky barrier at the electrode/GNR interface at each ends allows for an efficient directional flow of electrons, effectively separating the photo-generated carriers. The individual contributions at each electrode/GNR interface were summed up resulting in a larger absolute photo-induced current. The electron transfer characteristics of the DS-GNR-FET was studied under an irradiation of a light source with a wavelength of 632.8-nm at room temperature. The developed 70-nm DSGNR-FET showed a significantly larger and enhanced photosensitivity of about 1.6 × 107 A/W.m2 as compared to the device fabricated with identical metallic electrodes as the source and drain electrodes.
Design Optimization of Monoblade Autorotating Pods to Exhibit an Unconventional Descent Technique Using Glauert’s Modeling
Authors: Patnaik Shashwat , Kanishk
Published: January 2022

Many unconventional descent mechanisms are evolved in nature to maximize the dispersion of seeds to increase the population of floral species. The induced autorotation produces lift through asymmetrical weight distribution, increasing the fall duration and giving the seed extra time to get drifted away by the wind. The proposed bio-inspired concept was used to produce novel modern pods for various aerospace applications that require free-falling or controlled velocity descent in planetary or interplanetary missions without relying on traditional techniques such as propulsion-based descent and the use of parachutes. We provide an explanation for the design procedure and the functioning of a mono blade auto-rotating wing. An element-based computational method based on Glauert’s blade element momentum theory (BEMT) model was employed to estimate the geometry by maximizing the coefficient of power through MATLAB’s optimization toolbox using the Sequential quadratic programming (SQP) solver. The dynamic model was developed for the single-wing design through the MATLAB Simulink 6-DOF toolbox to carry out a free-flight simulation of the wing to verify its global stability.