bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterizing the Training and Evaluation of Graduate Teaching Assistants (GTAs) at Research-Intensive Universities: Highlighting Best Practices and Opportunities for Reform
Authors: Saxena Ankit , Hood Larkin , Manogharan Guha , Berdanier Catherine
Published: February 2023

Graduate Teaching Assistants (GTAs) play a crucial role in undergraduate and graduate education in Mechanical Engineering (ME). Depending on the course and course instructor, GTAs hold a variety of responsibilities such as grading homework and exams, interacting with students in labs and during office hours, proctoring exams, and administrative and technical assistance to faculty. In less frequent cases, GTAs create course content or take the lead in the classroom. In many engineering departments, especially at research-intensive universities, GTA appointments are reserved for first-year students who have not yet found research funding, or to cover a lapse in research funding. This structure reflects a prioritization of research over teaching, compounded by a documented lack of formal pedagogical training for GTAs. GTAs may receive training in the form of short workshops with information pertaining only to their duties as GTAs and are rarely provided with formal evaluations from students and faculty. As each university, department, and even individual supervising faculty have differing expectations, training, and evaluations of GTAs, the levels at which graduate students as future faculty are trained for pedagogical roles are, at best, inconsistent. To propose opportunities for best practices in the training and evaluation of GTAs in Mechanical Engineering, however, it is necessary to characterize different existing paradigms of GTA support across mechanical engineering departments. This paper seeks to answer the following questions:

1. What are the existing patterns in how ME departments manage and support their graduate teaching assistants

2. How do multiple stakeholders associated with GTAs characterize the expectations, training, and evaluation of teaching assistants?

To answer these research questions, we employ a content analysis of publicly available resources for Graduate TAs in Mechanical Engineering programs departments within the 14 universities in the Big 10+ academic alliance. Assuming the amount and the digital location/affiliation of digital resources corresponds with the integration of GTAs into departmental teaching priorities, our findings indicate a wide variety of different models through which GTAs are supported and evaluated. However, most Mechanical Engineering programs in the United States rely heavily on resources located outside of their respective Colleges of Engineering, leaning on the Graduate schools and universities more centrally, indicating only peripheral prioritization of the training and evaluation of GTAs. The patterns within these data lead to implications in terms of gaps in resources and summative assessment to better educate and evaluate GTAs to help them develop into the Mechanical Engineering faculty of the future.
Effects of Infill on the Additive Manufacturing of Piezoresistive Pressure Sensors
Authors: Banks James D. , Khaleghian Meysam , Emami Anahita
Published: February 2023

The surge of growth in additive manufacturing (AM) has brought about increased interest in smart devices and advanced manufacturing. Fused Filament Fabrication (FFF) often presents itself as the starting equipment for industrial applications and hobby enthusiasts. The introduction of conductive polymer composites into FFF has brought about widespread capabilities, particularly in the areas of flexible sensors, printed electronics, and other multi-functional materials. Piezoresistive sensors have especially been of interest due to their use in wearable electronics and structural health monitoring coupled with the increasing commercial availability of conductive thermoplastic filaments. However, while much research has been devoted to the geometrical parameters in piezoresistive sensors in conventional manufacturing, little has been investigated with respect to additive manufacturing. Here, we present a unique method for tailoring the sensitivity of FFF produced flexible pressure sensors by altering the infill printing settings, therefore affecting the electromechanical response. Sensors were printed using common infill patterns (Concentric, Grid, Gyroid, Honeycomb, Lines, and Cubic) and low infill percentages (5–15%) capable of sensitivities of 2,010 kPa−1 under an applied pressure of up to 60 kPa and 530 kPa−1 under an applied pressure of up to 950 kPa. This work demonstrates the ease-of-fabrication and performance of flexible pressure sensors using an inexpensive and simple fabrication method.
Utilizing Stent Wall Shear Stress to Assess Stent and Flow Diverter Performance for Treating Intracranial Aneurysms
Authors: Suess Taylor N. , Gent Stephen P.
Published: February 2023

Analysis of flow diverting intracranial aneurysm repair devices has traditionally focused on reducing intrasaccular blood flow velocity and aneurysm wall shear stress (WSS) as the primary metrics for improved perceived device performance. However, the interpretation of this data has been debated, particularly with regards to the specific biological benefits of high or low aneurysm WSS. Therefore, this research proposes an additional parameter of WSS at the stent struts that could provide valuable insight regarding the device’s potential to promote occlusion at the aneurysm neck by indicating potential locations of increased platelet activation and microparticle shedding. Fluid flow effects were evaluated for two flow diverters (Pipeline™ and FRED™) and three stents (Enterprise, Atlas™, and LVIS™) using computational fluid dynamics (CFD) models developed from two patient-derived CTA datasets with aneurysms in the middle cerebral artery (MCA) and basilar artery (BA), respectively. The device WSS data provides an additional metric for evaluating the ability of the device to constrain the blood flow within the main vessel, as well as determining the point at which the blood flow is released into the aneurysm, indicating the potential locations of the initiation of aneurysm occlusion. It is hypothesized that high device WSS close to the aneurysm neck creates a higher likelihood of aneurysm occlusion due to platelet activation and microparticle shedding, while high device WSS proximal on the device would indicate higher likelihood of undesirable daughter vessel occlusion. Conversely, low-to-moderate device WSS throughout the device length could be interpreted as less flow diversion and more consistent blood flow allowed into the aneurysm, resulting in lesser device performance.
Crystalline Phase Changes due to High-Speed Projectiles Impact on 304L Steel
Authors: Slewa Muna
Published: February 2023

The physical characteristics and molecular structure of 304L steel are well known; however, little is known about the high-velocity impact on this metal. The effects of high-speed velocity impact on the crystalline structure and material phase changes are studied experimentally. The effects of an impact on the crystalline structure are assessed by impacting 304L steel plates with Lexan projectiles. A two-stage light gas gun accelerates projectiles to a velocity of 6.58 km/s at the point of the impact. The impacted plates’ surfaces are inspected using the Electron Back Scatter Diffraction (EBSD). Nine regions are examined and analyzed. These regions are selected from the area immediately under the impact crater to locations not physically affected by the impact.

Observations of collected EBSD images show that the predominant phases are Body-Centered Cubic (BCC) and Face-Centered Cubic (FCC). A Hexagonal-Close-Packed (HCP) phase is also indexed. Since these crystalline structures are the most expected lattice formations, the samples are post-impact examined for molecular structure allocation changes. In this study, traces of HCP were found at some locations in all post-impact stages. This study also indicates that the FCC crystalline structure remained the dominant phase after impact. 304L steel iron alloys show resistance to phase changes behavior under high pressure shocks even close to the crater and impact holes.
A Physics-Based Computational Model for the Cold Spray Deposition of Composite Coatings
Authors: Abubakar Abba A. , Arif Abul Fazal M. , Akhtar Syed S. , Al-Athel Khaled S.
Published: February 2023

Composite coatings with tailored properties can be effectively deposited with the cold spray process via careful control of deposition parameters. To avoid repetitive experiments, numerical models are commonly used to optimize the cold spray deposition process parameters. The present study proposes using a physics-based hybrid computational approach to model the cold spray deposition of Ni-Ti/Al2O3 composite coating used for wear applications. The method involves using point cloud (for the impacting particles) and finite elements (for the deformed splats structures and substrate) to simulate dissimilar particles impact and interactions, plastic deformation, and temperature rise. The approach is computationally efficient and adequately captures the thermo-mechanical deformation resulting from the interactions among dissimilar particles. The simulations are carried out for various combinations of material types, particles sizes and shapes, and impacting velocities. The results from the simulations are analyzed and validated by comparing them with that of previous works. The plastic deformation and temperature rise within the mating bodies increase with increasing particles’ kinetic energies. The Ni-Ti-Al2O3 powder particles lead to higher plastic deformation, temperature rise, and inter-particle bonding due to the presence of the hard Al2O3 particles. The temperature does not rise above melting; however, recrystallization of coating microstructure becomes possible even at a low deposition rate.
Data Augmentation Using Spectral Failure Deltas to Diagnose Bearing Failure
Authors: Wescoat Ethan , Krugh Matthew , Mears Laine
Published: February 2023

Labeled training data are challenging to obtain in a manufacturing environment during production due to the time and cost constraints of the labelling process. Of the labeled training data that is collected, failure data comprises a small proportion or is non-existent in production datasets for condition monitoring. The small proportion can be related to failures occuring uxpectedly and parts are replaced quickly, meaning the failure state is rare and makes up a small portion of the run life and number of samples collected. The lack of labeled data and failure data leads to challenges in creating effective predictive systems, such as Digital Twins, to accurately determine equipment health state and remaining useful life. This work investigates training predictive algorithms using an augmented failure data set derived from laboratory systems with knowledge of real-world failures. Data are collected under different failure progressions and operating conditions to create variability for the variety of different production applications to apply these data augmentation methodologies. These same data are transformed by adding the variability measured through purposefully damaging the mechanical system to create the degraded and failed state data. This variability is extracted using a spectral augmentation technique on the surrogate system’s failure data under an artificial fatigue case. The fatigue case is created by incrementally damaging the bearing raceway and measuring the damaged surface area with respect to the total bearing raceway. The measured difference between these pre- and post-lab damage states is used as the damage state data set transformation function. The augmented and “true” data are then compared using class probability analysis and diagnosing particular failure instances. For future research, relatability analysis will be investigated to see how the effects change between bearings of different sizes.
Comparison of Residual Stresses in Cold Spray Coatings: Lagrangian vs. Eulerian Finite Element Methods
Authors: O’Donnell Jacob , Smith Michael , Cavallaro Paul
Published: February 2023

Cold spray is a novel thermal spray process in which a gas at high temperature and pressure deposits solid particles onto a substrate material. Current research utilizes a variety of methods of modeling techniques in order to capture the physics and dynamics of a cold spray particle impact, incorporating elements of the Lagrangian and Eulerian modeling methods. This research modeled the cold spray event of single and multi-particle impacts using Lagrangian and Eulerian methods. The material of both the particle and substrate are a standard Aluminum 6061-T6 alloy. The objectives of the models are to: (1) obtain particle and substrate deformations and residual stresses as functions of particle velocity, particle temperature, and substrate temperature; (2) establish the minimum number of successive particle layers such that the substrate residual stresses reach steady state; and (3) identify numerical limitations in the Lagrangian and Eulerian modeling methods using ABAQUS/Explicit.

The Lagrangian method predicted a maximum von Mises stress 23.72% lower than that of the Eulerian. The Lagrangian models allowed for discrete node tracking, however, thus allowing for improved surface definitions and transient material point tracking. The Eulerian models also better handled the plastic deformation and resultant temperature generation within the model, and thus were able to handle multiple particle impacts while the Lagrangian could not. The multi-particle models using the Eulerian method reported that seven particles were required for the substrate steady-state stress to remain independent of subsequent particle impacts. Concentric initial position multi-particle models saw a maximum 42.00% reduction in von Mises stress compared to the single-particle models and a maximum 53.18% reduction compared to multi-particle modes with randomized initial particle positions. Multi-particle impacts demonstrated a reduction in stress when compared to the single particle impact due to the increased thermal softening present.
Prototype Design and Manufacture of a Deployable Tensegrity Microrobot
Authors: Kazoleas Christian , Mehta Kaushik , Yuan Sichen
Published: February 2023

Micro-, and milli-scale robots have been of great R&D interest, due to their ability to accomplish difficult tasks such as minimally invasive diagnosis and treatment for human bodies, and underground or deep-sea tests for environment monitoring. A good solution to this design need is a multi-unit deployable tensegrity microrobot. The microrobot can be folded to only 15% of its deployed length, so as to easily enter a desired working area with a small entrance. When deployed, the tensegrity body of the robot displays lightweight and high stiffness to sustain loads and prevent damage when burrowing through tightly packed tissues or high-pressure environments. In this work, topology, initial configuration and locomotion of a deployable tensegrity microrobot are determined optimally. Based on the design, a centimeter-scale prototype is manufactured by using a fused deposition modelling advanced additive manufacturing or 3-D printing system for proof of concept. As shown in experimental results, the deployable tensegrity microrobot prototype designed and manufactured can achieve an extremely high folding ratio, while be lightweight and rigid. The locomotion design, that mimics a crawling motion of an earthworm, is proved to be efficient by the prototype equipped with stepper motors, actuation cables, control boards and a braking system.
Comparative Analysis of Coefficient of Performance (COP) Correlations of Single-Effect Vapor Absorption Refrigeration (VAR) Cycle
Authors: Khan Muhammad Saad , Kadam Sambhaji T. , Kyriakides Alexios-Spyridon , Hassan Ibrahim , Papadopoulos Athanasios I. , Rahman Mohammad Azizur , Seferlis Panos
Published: February 2023

Most of the absorbent-refrigerant pairings are evaluated considering single-effect vapour absorption refrigeration (VAR) cycle. The coefficient of performance (COP) based modelling of VAR enables its quick performance evaluation. The development of efficient and environmentally benign fluid pairing is required to replace conventional refrigerants. Operating parameters-based COP models are scarce for single-effect VAR systems, and fewer correlations are available for the COP estimation. The paper compares five performance-based models reported in the literature for operating absorption cooling systems with various refrigerant and absorbent pairing. The comprehensive mean absolute percentage error (MAPE) analysis was performed for five reported correlations for more than 1601 data points of different fluid pairings. Results revealed that RMSD and MAPE values seem significantly higher for the reported correlations apart from the recently developed COP correlation accounted for fluid parameters in prediction. This indicates that the earlier reported correlations only accounted for the specific fluid pairing and could not incorporate different fluid pairing, which has been considered a recently reported correlation that resulted in the significantly improved prediction ability for COP. The finding from this study highlighted that the newly registered COP prediction correlation could be beneficial for developing new single-effect VAR cycles as it accounted for both the operating parameters and fluid parameters.
Effect of Process Parameters on Wall Thickness Uniformity of Integrated Forming of Hollow Axle
Authors: Ye Caoqi , Shu Xuedao , Li Yiman , Xu Haijie , Wang Jitai , Xia Yingxiang
Published: February 2023

This paper innovatively puts forward the integrated forming of shape and hole of hollow axle. For verifying the feasibility of this method, the integrated forming of hollow axle is simulated by finite element method, and the hollow axle with good forming quality is obtained. On this basis, the effects of feed angle of the disc roll on the wall thickness uniformity of the middle long shaft section are explored. In order to characterize the wall thickness uniformity of each shaft, eight longitudinal sections are taken on each long shaft section, the wall thickness variance of the longitudinal section is calculated, and then the average value of the wall thickness variance of the eight longitudinal sections is used to represent the uniformity of the long shaft section wall thickness. The simulation results show that with the increase of the feed angle of the disc roll, the wall thickness of the long shaft section becomes more uneven, but the increase of the feed angle of the disc roll will improve the rolling efficiency; This paper expounds the influence law of feed angle on the wall thickness uniformity of hollow axle with integrated forming, which provides a theoretical basis for realizing the short and accurate forming of hollow axle.
Understanding the Influence of Process Parameters for Minimizing Defects in 3D Printed Parts Through Remote Monitoring
Authors: Bhandarkar Vivek V. , Patil Ishant G. , Shahare Harshal Y. , Tandon Puneet
Published: February 2023

Although fused deposition modeling (FDM) can fabricate complex functional components with desired structures, various defects emerge due to the diverse process parameters used in the process, which have a substantial impact on the quality and mechanical properties of the manufactured FDM parts. Therefore, the selection of suitable process parameters is an important design consideration for improving component quality. In the proposed work, the Taguchi optimization approach was used to optimize FDM process parameters to eliminate warpage defects in 3D printed parts. Infill pattern, infill density, raster angle, printing speed, layer height, build plate temperature, and extruder temperature were selected as the process parameters. Polylactic acid (PLA) was used to make the specimens using the Creality Ender-3 3D printer. The entire fabrication process was remotely monitored by interfacing the Raspberry Pi controller and camera with the OctoPrint platform. The influence of selected factors on warpage defect was evaluated and optimized using Analysis of Variance (ANOVA), the signal-to-noise ratio (S/N ratio), and a linear regression model. The results were later experimentally validated. The applicability of the optimized 3D printed part was verified by subjecting them to tensile tests.
Type X Robot: Theory and Practice for a Revolution in Motor Learning
Authors: Zhang Danqing , Weaver Jonathan M.
Published: February 2023

This research proposes and tests the concept of using a robot to train a subject to perform a desired repetitive motion, wherein the level of the assist of the robot fades away as the subject learns the motion. The proposed robot is designated as Type X where the “X” in represents the variable level of autonomy. A Type X robot has been built and tested, with the experiment results suggesting that transient learning using the Type X provides clear and statistically better training of a repetitive motor task than was achieved through purely active learning (no robot assist) or purely passive learning (the robot is in full control of the motion during training).
Analysis of 3D Printing Performance Using Machine Learning Techniques
Authors: Kabengele Kantu Thomas , Tartibu Lagouge Kwanda , Olayode Isaac Oyeyemi
Published: February 2023

Additive manufacturing (AM) or 3D printing is gaining momentum in the market compared to conventional subtractive technologies due to its ability to speedily produce complex and customized geometries with less waste of material. Some 3D printing parameters are influential or crucial as they affect the final part’s mechanical properties based on the technology used. These are the printing height, the printing rate, the nozzle diameter, the nozzle movement rate, the layer thickness, the temperature, the ventilator speed, the print precision, the layer thickness, the type of infill, and the extrusion. This paper proposes the development of a neural networks model (ANN) and a hybrid neural network trained by particle swarm optimization (ANN-PSO) to get an insight into the selection of 3D printing parameters and adjust them. To ensure the quality of the 3D printing, a parametric analysis has been performed to identify the best configuration of the models. Readily available data has been used to demonstrate the potential of the proposed approach. These data have been used to train and test the algorithms and build robust models able to predict performance. The ANN and the ANN-PSO models have exhibited good overall performance that demonstrates the potential for modelling and prediction of 3D printing performance using machine learning techniques.
Probabilistic Reliability Analysis Method Based on Surrogate Model for Wind Turbine Drivetrain Structure Subjected to Random Dynamic Load
Authors: Jimbo Tomohiko , Kano Akira , Hisakuni Yousuke , Ito Yasutaka , Hirohata Kenji , Ichimura Tsuyoshi
Published: February 2023

In order to improve the mechanical reliability for wind turbine drivetrain structure subjected to random dynamic load, commercial load and fatigue calculation method is developed based on stochastic and stochastic methods (extreme statistics) of the mechanical composition part to the random dynamic load due to the effects such as wind and the earthquake. Evolutionary spectrum is introduced from the analogy with a concept of a dynamic design wave. An attempt is made for random dynamic load calculation and fatigue prediction of 2MW wind power generation plant by the strong wind and earthquake using large-scale structural analysis based on Finite Element Method and Surrogate Modeling Method based on machine learning with physical model.
Darrieus Wind Turbines With Twisted Blades
Authors: Sutariya Yashkumar Rameshbhai , Zhou Hong
Published: February 2023

Darrieus wind turbines are lift-type vertical axis wind turbines. They have merits of simple structure and construction, easy installation and maintenance. Darrieus wind turbines can capture wind from any direction and convert it into electric power. They do not need any yaw mechanism to adjust their orientations in order to make their rotors face wind direction. Because of their lift-type, the power conversion efficiency is relatively high compared with drag-type vertical axis wind turbines like Savonius wind turbines. Although the merits of Darrieus wind turbines are remarkable, they also have their demerits. Compared with other types of vertical axis wind turbines, Darrieus wind turbines have relatively low static torque that weakens their self-starting capability. This research is motivated by surmounting the disadvantages facing Darrieus wind turbines. The research objective is focused on improving Darrieus wind turbines’ static and dynamic performance. In this research, Darrieus wind turbines with different blade shapes and numbers are simulated. The effects of the design parameters on the performance of Darrieus wind turbines are analyzed. Darrieus wind turbines are designed based on their geometric parameters to improve their performance. The results from this research will help the development and promotion of Darrieus wind turbines.
Solar Tracking Using Four-Bar Mechanisms
Authors: Munoz Saul , Zhou Hong
Published: February 2023

Solar tracking adjusts the orientation of solar panels and makes them face Sun to increase power generation. The Earth has two movements with respect to Sun: the daily axial rotation and the yearly orbital revolution. There are two degrees of freedom in the relative motion between Earth and Sun. For solar tracking, Earth is commonly considered to be stationary while Sun takes relative motion with respect to Earth. Sun travels from east to west during daytime and also moves north and south due to Earth’s tilt. However, Sun’s daily north-south move is much smaller than its east-west move. Although the existing solar trackers with two degrees of freedom increase solar power generation from solar panels significantly, they also consume considerable power by driving solar trackers. Single-axis (or one degree of freedom) solar trackers can catch Sun’s daily east-west movement effectively. Sun’s small north-south movement can be covered for them by monthly or seasonal manual adjustment of their orientations. This research is focused on single-axis solar trackers that have one degree of freedom. Four-bar mechanisms (or linkages) consist of four links that are connected by revolute or prismatic kinematic joints in a closed loop. They are the simplest mechanisms with one degree of freedom. Four-bar mechanisms have been widely used in various mechanical devices for different applications. Properly designed four-bar mechanisms can generate the output motion to meet the solar tracking requirements. However, single-axis solar trackers that are based on four-bar mechanisms also face challenges such as limited solar tracking motion range, high actuation power consumption, lacking self-locking function. This research is aimed at circumventing the challenges on solar trackers that are constructed of four-bar mechanisms. In this research, 4R and 3R1P four-bar mechanisms are designed for generating solar tracking output motion. Their kinematic and dynamic performances are analyzed and simulated. The results from this research will provide guidelines for developing and promoting single-axis solar trackers using four-bar mechanisms.
Vapour Cough Visualization for COVID-19 – Computational Modelling Approach
Authors: AL-Rawi Mohammad , Al-Jumaily Ahmed M.
Published: February 2023

New Zealand and many countries gained heightened awareness of indoor air quality (IAQ) issues, and increased investment, according to the World Health Organization (WHO) guidelines, to improve their IAQ and reduce air pollution in commercial and residential buildings. Additionally, some countries have introduced new standards for indoor environments, such as the New Zealand “healthy homes” standard. At the same time, COVID-19 pandemic forced many people to spend much more time in indoor spaces, due to stay-at-home, or lockdown orders by governments. This increased attention on other aspects of indoor environmental quality, such as occupants’ satisfaction with thermal comfort parameters, presents an additional parameter for research and in the development of standards. From a medical perspectives, infectious respiratory diseases, such as influenza or COVID-19, are transmitted by airborne droplets. In this work, we assess a Polyester Filter and UV light (PFUV) dehumidifier device performance in an office with two occupants (one uninfected and the other one infected with a disease with airborne transmission using computational fluid dynamics (CFD) approach. Two positions for locating the PFUV dehumidifier in an office with a scenario in which one person is exhaling infected air and the other occupant must inhale and exhale from the shared air. The CFD model illustrated the best position of the device to distribute the air velocity contours. Further, based on the CFD model which was validated via the IAQ and comfort kit (Testo 400) thermal comfort analysis showed that the room is slightly cold.
Microstructure Evolution and R-Phase Transformation in NiTi Shape Memory Alloy Processed by Constrained Groove Pressing and Ageing Treatment
Authors: Bhardwaj Akhil , Mathur Devanshi , Oswal Kunthal , Gupta Amit Kumar
Published: February 2023

R-phase transformation has been known to originate from thermomechanical processing, ageing and microalloying various elements in NiTi. R-phase transformation has been known for high cyclic fatigue resistance, higher stability but in short range of 1%–2% strain thus, possess high potential for sensors, actuators, dampers and elastocaloric cooling applications. Constrained groove pressing (CGP) is well known sheet metal severe plastic deformation technique for grain refinement. In this study, the microstructure evolution and R-phase transformation has been analyzed first time in NiTi sheet processed by CGP and ageing treatment. The CGP leads to severe plastic deformation and grain refinement while post ageing resulted into Ni4Ti3 precipitation. This gives rise to improvement and stabilization of R-phase transformation, larger R-phase transformation and higher martensite stress during cyclic loading as compared to the water quenched NiTi alloy. These improvements will help to extend nitinol sheet-based applications domain which utilize R-phase transformation.
Enhanced Fault Detection of Vehicle Lateral Dynamics Using a Dynamically Adjustable Bayesian Network Structure and Extented Kalman Filter
Authors: Bodrumlu Tolga , Gözüm Mehmet Murat , Kavak Batıkan
Published: February 2023

In order to improve reliability and safety in many technical systems; the importance of the fault diagnosis and detection is increasing day by day. This is particularly important in safety-related industries such as airplanes, trains, automobiles, power plants, and chemical plants. In this study, a model-based fault detection method that can detect faults affecting the lateral dynamic system of a vehicle is proposed. The developed fault detection algorithm includes both Bayesian Network and Extended Kalman Filter (EKF). EKF plays an effective role especially in detecting the faulty speed measurements. In the fault detection algorithm, six residual values are calculated. The threshold values of all the calculated residuals are determined using real test dataset. Depending on whether the residuals exceed the threshold value or not, the fault generation coefficients in the Bayesian Network are also dynamically updated to provide precise information regarding which sensor has a fault. The implementation of the fault detection algorithm is carried out using real test data and the numerical simulations are performed in MATLAB/Simulink environment. The results show that the proposed fault detection algorithm gives over 92% fault probability by using Bayesian and EKF structure together.
Learning by Doing in the Dynamics and Mechanical Vibrations Courses Using 3D Printed Equipment
Authors: Tran Thuong , Tran Tinh , Tran Kevin , Oun Karena , Tekes Ayse
Published: February 2023

Limited resources available to the engineering faculty and students impede student learning and deep understanding of the material that is presented in the dynamics and mechanical vibrations courses. Active learning practices such as learning by doing is an effective way to not only build a solid foundation in knowledge but also help students develop engineering skills. However, these courses are mainly taught in a traditional manner and many students struggle in connecting the theory to its real-world application and lose interest. Although mechanical engineering students get more hands-on opportunities in the laboratories, they take vibrations and control laboratories in the following semesters since vibrations is a pre-requisite for these labs. To address this issue, we designed 3 low-cost, compact, and portable laboratory equipment and fabricated them using 3D printing technology. The first equipment is a 3-pendulum system with different lengths and tip loads that can be utilized in the engineering dynamics course. While the second equipment is a 2 DOF compliant vibration isolator consisting of flexible beams, masses, and a linear actuator, the third equipment is a non-linear cantilever beam to be utilized in the vibrations courses and their associated laboratories.
Biventricular Statistical Shape Atlas of Unloaded Reference Geometries: A Novel Method to Control for Hemodynamic Variations in End-Diastolic Pressure
Authors: Crabb Brendan T. , Govil Sachin , Hegde Sanjeet , Perry James C. , Young Alistair A. , Omens Jeffrey H. , Kim Hyong , Valdez-Jasso Daniela , Contijoch Francisco
Published: February 2023

Biventricular statistical atlases are useful dimensionality reduction tools that have demonstrated utility for discovering improved diagnostic and prognostic markers. Patient-specific geometries used to generate these atlases are obtained from in-vivo tomographic images of end diastole (ED) and/or end-systole (ES). However, because these are pressure loaded states, variations in hemodynamic loading may impact downstream shape analysis. In this project, we used a computationally expensive, iterative method to estimate the ventricular geometry in the absence of hemodynamic loading and quantified the shape difference between pressure loaded and unloaded states using a statistical atlas. Next, we assessed whether these atlas-based shape differences could be used as an accurate initial guess for the iterative method, thereby improving the convergence time. In a cohort of 23 patients with chronic thromboembolic pulmonary hypertension (CTEPH), hemodynamic unloading produced atlas-based z-score changes that were highly conserved between patients, with absolute differences between the loaded and unloaded states of 1.0 ± 0.14, 1.2 ± 0.27, −0.1 ± 0.08, and 0.5 ± 0.08 for the first 4 shape modes, respectively. When we used these atlas-based z-score changes as an initial guess, we observed a 72% decrease in required CPU time to solve for patient-specific unloaded geometries.
Lateral and Transverse Movable Mass Impacts on Bandwidth of Kinetic Energy Harvesters
Authors: Jackson Nathan
Published: February 2023

Vibrational energy harvesters have significant potential to replace batteries to create self-sustaining systems able to harvest energy from the ambient environment. However, currently high Q-factor or low bandwidth is a major challenge that needs to be resolved, as typical linear MEMS energy harvesters have a frequency bandwidth of about 1–3 Hz. Various methods to increase the bandwidth have been investigated but, they often result in a significant reduction of power. This study investigates a new method of increasing bandwidth without significantly reducing power. The study experimentally investigates the use of lateral and vertical moving masses to solve this problem. Vertical movable masses create non-linear dynamics to increase the bandwidth but also results in lowering the power, whereas lateral moving masses have a slight increase in bandwidth but almost no reduction in power. By combining these methods, it was demonstrated that a device can be created that increases bandwidth by > 1000% with only a 54% reduction in peak power. This paper demonstrates a proof of concept at the macro-scale and provides researchers with valuable information to allow them to tune the power and bandwidths to meet their application specifications.
Promoting Globalization of Engineering by Developing Students’ Potential for Productive Communication and Interaction Using Transactional Analysis in a Historically Black College and University
Authors: Addo Sampson , Tyagi Pawan , Gaye Samba , Baker Kaiya
Published: February 2023

Previous research has indicated the importance of effective communication in globalization as individuals from different countries, languages, cultural inclinations, and other background variations need to understand one another and express themselves to work effectively together. Our ability to interact with others productively during our adulthood has been linked to what happened in our early childhood. Of particular importance to effective interaction is the study by Dr. Eric Berne, a psychologist, who developed the term Transactional Analysis (TA) in the 1950 and the 60s. Transactional analysis is defined by the International Transactional Analysis Association as a theory of personality and a systematic psychotherapy for personal growth and personal change. Dr. Berne postulated that adulthood reactions to situations are largely determined by the treatment received from main caregivers during early childhood (that is birth to 5 years). As part of his theory of personality, he identified three ego-states known as Parent (P), Adult (A), and Child (C). Over the years, Dr. Berne’s theory has been applied in varied fields such as counseling, psychotherapy, organizational development, and education, and various studies have assessed its effectiveness in a wide variety of contexts. However, little research has been done to develop engineering students’ potential for effective communication to promote the globalization of engineering, after being taught TA using Student Presentation Based Effective Teaching (SPET). This study seeks to promote the globalization of engineering by developing students’ potential for productive communication using Transactional Analysis. To achieve this, we developed a Transactional Analysis Tool to evaluate the communication traits of engineering students taught TA through SPET in the MECH 500 Research Experience and Technical Communication (RETC) course and that of a control group, who were not taught TA. The results indicate engineering students introduced to TA, have a high level of self-awareness to effectively communicate globally when compared with that of the control group. We believe that to promote the globalization of engineering, it is important that engineering students’ productive communication competencies are developed through concepts such as TA and Positive Intelligence, by including these in universities’ engineering curricula.
Effect of Spinning Process Parameters on Roundness of Aluminum Alloy Wheel Hub Surface and Analysis of Springback Characteristics
Authors: Chen Siyuan , Shu Xuedao , Lu Yujie , Zheng Jiabin
Published: February 2023

This paper mainly studies the effect of process parameters on the roundness of the outer surface of the wheel hub during the spinning process of the forged and Spinned aluminum alloy wheel hub and summarizes the laws of the spring back phenomenon. Firstly, based on the finite element analysis platform of Simufact. Forming, the finite element simulation model of the spinning and forming of 6061 aluminum alloy wheel hub was established in this paper. Then, the spinning process of the 6061 aluminum alloy wheel hub was numerically simulated by using simulation software. Four main process parameters (temperature, feed rate, thinning rate, spindle speed) were selected for the single factor simulation analysis of four factors and five levels. The results show that the optimum process parameters are that the spindle speed is 400 r/min, the temperature is 400 °C, the feed rate is 0.75 mm/r and the thinning rate is 40%. The influence of process parameters on roundness error is as follows: feed rate > thinning rate > spindle speed > temperature. The influence of process parameters on spring-back of 6061 aluminum alloy wheel hub is as follows: thinning rate > feed rate > temperature > spindle speed. The factor that has a greater influence on the fluctuation of spring back is as follows: roller feed rate > thinning rate.
Reversible Geometric Constraint Programming on Kinematic Analysis and Synthesis of Planar Linkages
Authors: Ting Kwun-Lon , Chan Cody Leeheng
Published: February 2023

This paper proposes a novel reversible approach to do the kinematic analysis and synthesis for higher-order motion. The method plots the traditional velocity and acceleration polygon in the sketch mode of commercial computer aid design (CAD) software. Based on the geometric constraint and the aid of similar triangles, the approach can synthesize the linkages with prescribed velocity and acceleration at the specified positions. The approach shows the analysis results at the same time when the synthesis process is finished, it is conceptually intuitive and does not require Euler-Savary equation and advanced computational techniques. The approach can be used as an ideal tool to teach undergraduate students about the graphical method of kinematic analysis. With a similar setting, the synthesis process can be introduced by reversible programming. This paper demonstrates the procedure by synthesizing a four-bar linkage with the prescribed velocity and acceleration of its coupler point, and extends the method to synthesize a Stephenson six-bar linkage. It is a simpler and more intuitive approach of order synthesis for planar linkages, and it may have the potential to make the analysis and synthesis of spatial linkages easier.
Effect of Strain Rate on the Creep-Fatigue Damage of Polycrystalline Ni-Base Superalloy at Elevated Temperature
Authors: Nakayama Koki , Miura Hideo
Published: February 2023

Ni-based superalloys used for thermal power plants have been subjected to random creep-fatigue load in high-temperature environment to counter global warming and compensate the fluctuation of the output of renewable energies. However, under the creep-fatigue condition, intergranular cracking was found to be accelerated, and the fracture life of the alloy was significantly decreased. Therefore, it is essential to elucidate the mechanism of this acceleration of crack propagation rate and to develop a quantitative evaluation method of the creep-fatigue damage. In this study, intermittent creep-fatigue tests were applied to Alloy 617, one of the Ni-based superalloys, and the degradation process of its crystallinity was monitored by EBSD (Electron Back-Scatter Diffraction) method. In particular, the effect of strain rate during loading and unloading processes were evaluated in detail. IQ (Image Quality) value which indicates the quality of crystallinity, in other words, the concentration of various defects and Schmid factor were applied to the crystallinity analysis, and the degradation process of the microstructure was continuously monitored. The results showed that under creep-fatigue loading, the faster the strain rate during unloading, the earlier the IQ value decreased and the shorter the time for the initiation of intergranular cracking. It was also found that intergranular cracking appeared when the IQ value reached a critical value regardless of the strain rate. The creep-fatigue damage was mainly accumulated grain boundaries with large difference in Schmid factor between nearby grains, indicating large local strain due to the large lattice mismatch. The unloading rate was one of the dominant factors of the degradation of the crystallinity around grain boundaries.
Methodology for Integrating Biomimetic Beams in Abstracted Topology Optimization Results
Authors: Röver Tim , Lau Robert Johannes , Lange Fritz , Struve Arnd , Fuchs Cedrik , Bartsch Katharina , Seibel Arthur , Emmelmann Claus
Published: February 2023

This paper presents a five-step design methodology to generate designs of biomimetic structural components from topology optimization results. In step one, all material allocated by topology optimization is classified as either beam like structures or nodes to generate an auxiliary model consisting of preserved regions, cylindrical beams, and ball nodes, which is an abstraction of the original topology optimization result. In step two, the auxiliary model is exposed to the original boundary conditions in a finite element analysis. Then, internal forces, torsion, and bending moments in all beams of the auxiliary model are identified with respect to both of their ends. In step three, a database is used to find a suitable biomimetic beam for each previously analyzed beam in the auxiliary model. In step four, adapted nodes are designed to connect the biomimetic beams and preserved regions to generate an intermediate biomimetic component design. And in step five, a design iteration and a validation of the final design are performed. The design methodology allows for reproducible bio-mimetic component designs, a trackable and easily documentable component development process, and the possibility of automating the design process to ultimately save development costs when designing structural components.