bluuebunny/crossref_metadata_2025_split huggingface dataset:
Improving CFD Simulations by Local Machine-Learned Corrections
Authors: Mitra Peetak , Haghshenas Majid , Dal Santo Niccolo , Daly Conor , Schmidt David P. 
Published: February 2024

Abstract
High-fidelity computational fluid dynamics (CFD) simulations for design space explorations can be exceedingly expensive due to the cost associated with resolving the finest scales. This computational cost/accuracy trade-off is a major challenge for modern CFD simulations. In the present study, we propose a method that uses a trained machine learning model that has learned to predict the discretization error as a function of large-scale flow features to inversely estimate the degree of lost information due to mesh coarsening. This information is then added back to the low-resolution solution during run time, thereby enhancing the quality of the under-resolved coarse mesh simulation, aposteriori. The use of a coarser mesh produces a non-linear benefit in speed while the cost of inferring and correcting for the lost information has a linear cost. We demonstrate the numerical stability of a problem of engineering interest, a 3D turbulent channel flow. In addition to this demonstration, we further show the potential for speedup without sacrificing solution accuracy using this method, thereby making the cost/accuracy trade-off of CFD more favorable.
Effects of Knee Hyperextension on Transtibial Amputate Gait
Authors: Moreno-Agudelo Daniel , Ortega-Bedoya Yessika , Valencia-Legarda Fanny , Rendon-Velez Elizabeth 
Published: February 2024

Abstract
This article presents an exploratory study investigating the kinematic variations made by transtibial amputees during gait with knee hyperextension. Other authors have studied other abnormal amputee gait patterns like circumduction or vaulting. The within-subject study involved 20 participants and used the MVN Awinda Motion Capture System to record kinematic variables during gait cycles. Knee hyperextension was induced by using a 3D-printed outsole placed on the prosthetic foot in order to restrict the ankle dorsi-flexion angle. The condition was verified by inspecting the kinematic curve of this joint in the sagittal plane. After this inspection, two groups were identified based on flexion-extension angles during mid-stance: one group had a constant flexion-extension angle during this sub-phase and the other one had a fluctuating angle. Differences between control and hyperextension trials were found in ankle, knee, and hip joints. Group 1 showed higher values for ankle flexion on the healthy limb during all gait events in the control trial and higher hip abduction and shoulder flexion during all gait events during hyperextension trials. Group 2 presented higher values for the healthy knee abduction during heel strike and load response and hip abduction on the amputated side during load response and terminal extension during knee hyperextension trials. Future studies should consider using physiological information such as electromyography to deepen understanding of this abnormal gait pattern. These findings have important implications for early diagnosis and prevention of future difficulties resulting from knee hyperextension in transtibial amputees. The presented findings can be implemented in the creation of automated gait pattern detection algorithms as well.
A Framework for In-Situ Vision Based Detection of Part Features and its Single Layer Verification for Additive Manufacturing
Authors: Saini Tushar , Shiakolas Panos S. 
Published: February 2024

Abstract
Additive manufacturing (AM) is a layer-by-layer manufacturing process that has become a popular technique to produce complex components with high precision and accuracy. The presence of internal defects and geometrical issues in a layer can significantly affect the quality of a 3D-printed part. In this research, we propose an in-situ framework that offers a systematic approach for detecting features on a layer-by-layer basis during the manufacturing process and compare them with the as-designed ones. A single high-resolution camera controlled by a Raspberry Pi is used. The acquired images are processed by a computer vision algorithm implemented in the Python programming language. The framework uses techniques such as image segmentation and edge detection to analyze and extract internal features at each printed layer. Subsequently, the identified features are compared with the as-designed ones based on the generated GCODE. The proposed framework is evaluated on a single-layer; a 20mm square shaped test sample with different distinct shaped internal features. These features are automatically compared to the as-designed model to assess and highlight any differences between them. Initial results show that the proposed framework is highly effective in detecting sub-millimeter errors between the as-designed and printed in-layer features and alerting the operator in real-time of any differences outside an acceptable error level. These differences could be employed to decide whether to continue printing, attempt repairs or abort the fabrication thus improving quality control and reduce waste. The developed system is a cost-effective solution that can be easily integrated into existing additive manufacturing systems.
A Deep Learning-Based Method for Early Crack Diagnosis in Non-Standard Spur Gear Pairs
Authors: Kalay Onur Can , Karpat Fatih , Karpat Esin , Dirik Ahmet Emir , Ekwaro-Osire Stephen 
Published: February 2024

Abstract
Gears are the key components of modern industry and have been widely employed in the automotive, wind turbine, and aviation fields. From the engineering point of view, an intelligent method that can automatically extract fault features from the vibration signals would be precious since failing in early diagnosis of root cracks may result in a tooth broken rapidly. In this regard, deep learning (DL) is increasingly popular in achieving early fault diagnostics tasks in geared systems with the wide availability of sensors and ever-increasing computation power. With this in mind, the asymmetric tooth concept offers higher load-carrying capacity, long fatigue propagation life, and the ability to lessen vibration and noise than the standard (symmetric) involute profile spur gears. From this standpoint, this study aims to determine the tooth root crack and its degree for both symmetric (20°/20°) and asymmetric (20°/30°) involute spur gears with a DL-based approach using vibration data. To this end, the single tooth stiffness values of the designed gears were obtained with ANSYS software for healthy and cracked gears (50%–100%), and then the time-varying mesh stiffness was calculated. Besides, a six-degree-of-freedom dynamic model was developed by deriving the equations of motion of a one-stage spur gear transmission. The vibration responses were collected for the healthy state, 50%, and 100% crack degrees for symmetric and asymmetric tooth profiles. Three different signal-to-noise ratios were considered to complicate the early crack diagnosis task and evaluate its influence on the DL algorithm’s classification performance. The obtained findings were then evaluated and interpreted in time and frequency domains. To this end, the Fourier transform was applied to the simulated time-sequence acceleration data in the time domain. As a supplementary finding, the present research also benefited from three statistical indicators, namely, (1) root mean square, (2) kurtosis, and (3) crest factor, to investigate whether the configuration of tooth profiles would provide an advantage in detecting tooth-root cracks. The present study also evaluated the influence of residual signals on the proposed DL-based method’s classification accuracy and further expanded the scope of research work. The findings indicated that the overall classification accuracy could be improved by 5.1% using asymmetric (20°/30°) gearing.
A Slicing Method for Spherical Additive Manufacturing
Authors: Kim Christopher D. , DeVries Levi D. , Kutzer Michael D. M. 
Published: February 2024

Abstract
Fabrication using additive manufacturing (AM) or 3D printing technology is ubiquitous across a growing number of disciplines. Despite a wide variety of AM methods ranging from extrusion of polymers to laser sintering of metals, the use of flat layers or “slices “ is common practice for deposition planning and execution. While effective, observations of other well-understood fabrication methods and testing conducted on AM prints reveal the importance of print fiber arrangement; otherwise known as grain orientation. By expanding AM capabilities to allow for fabrication using alternate grain orientations, AM workpieces see an improvement in anisotropy, surface finish, and physical properties. This paper presents a new approach to AM based on conformal layering that produces spherically wrapped grain.
Complex Dynamic Phenomena in Circular Cylindrical Shells
Authors: Pellicano Francesco , Iarriccio Giovanni , Zippo Antonio 
Published: February 2024

Abstract
In this paper the achievements of an intense experimental champaign, regarding shell nonlinear dynamics with and without fluid interaction, with thermal effects, subjected to harmonic or random excitations, is presented. Extreme thermal conditions, and high thermal gradients across the thickness of the shell cause important effects on the shell dynamics: a test setup has been developed to perform tests in climate chamber, in order to investigate the dynamics under different conditions, both for empty and a fluid-filled shells as well as for Newtonian and non-Newtonian (dilatant) fluids.
The response is strongly non-linear due to the couplings between fluid-structure-shaker which lead to a complex dynamic scenario. In the case of harmonic excitation, experiments show the onset of complex dynamics: subharmonic and quasiperiodic responses, Chaos. In the case of high-energy random excitation a synchronicity phenomenon was detected for particular thermal and loading conditions: a severe transfer of energy from a broadband excitation to almost harmonic response is experimentally observed; energy transfer to low frequencies was observed as well.
Enhancing Thermal Comfort and Air Quality in a Classroom Using Air Filtration Boxes
Authors: Kokash Hussein , Khanafer Khalil , Burzo Mihai G. 
Published: February 2024

Abstract
This study presents a numerical simulation of a classroom’s indoor environment using Fluent Ansys to investigate the effectiveness of air filtration boxes in maintaining good indoor air quality (IAQ) and thermal comfort while reducing the spread of airborne particles. The simulation examines the distribution of aerosol particles released by occupants, the airflow patterns, and the concentration of pollutants in a typical classroom with a ventilation system consisting of supply and return air diffusers and air filtration boxes. The results demonstrate that the placement and location of the air filtration boxes significantly impact IAQ and thermal comfort, and the proposed template can guide researchers in optimizing ventilation strategies. More specifically, our results show that more filtration boxes are not always better or desirable. As few as two filtration boxes placed strategically in the classroom can be as effective as using more boxes. The study highlights the importance of maintaining good IAQ and thermal comfort in classrooms, especially during the COVID-19 pandemic. The use of air filtration boxes is a cost-effective and easy-to-install solution that can help filter out pollutants and reduce the spread of airborne virus particles. The findings of this study can contribute to creating safer and healthier indoor environments in classrooms and have implications for the health and productivity of occupants.
Developing a Modular Control Moment Gyroscope for Planetary Rover Mobility
Authors: Han Fang , Wiles Jeremy , Brawley Aidan , Sanderson Oliver , Burke Stephen , Radhakrishnan Pradeep 
Published: February 2024

Abstract
A control moment gyroscope (CMG) is a torque actuator typically used for spacecraft attitude control, but other applications of CMGs are seldom seen in practice. The goals of this project were to design, manufacture, and analyze a modular CMG for use in any application. The developed prototype consisted of a turned brass flywheel suspended in a servo-powered, aluminum gimbal structure and was able to produce a nominal output torque of up to 6 Nm. A microcontroller was used to simulate CMG dynamics, control the motors, and calculate performance metrics. Quantitative analyses were conducted for the behaviors of the motors, dynamic disturbances in the system, and stresses in the structure. To further validate the design, its output torque performance was evaluated against a theoretical CMG model developed in Simulink. Subsequently, to exemplify the prototype’s modularity, its use on planetary rovers for rollover prevention, rollover recovery, and entrapment recovery was substantiated through computer simulations. Rollover recovery was also physically demonstrated. These applications aimed to address NASA’s Space Technology Grand Challenge of “All Access Mobility,” which identifies the need for next-generation rovers to safely traverse any terrain type.
Improved Non-Contact Ultrasonic High-Speed Structural Condition Monitoring of Rails Using a Controlled Acoustic Source and Random Wheel Generated Excitations
Authors: Datta Diptojit , Hosseinzadeh Ali Zare , Batista Izabela , Lanza di Scalea Francesco 
Published: February 2024

Abstract
Internal defects in rails are a major contributing factor in train derailment related accidents. A non-contact ultrasonic passive rail defect detection system is currently being developed at the Experimental Mechanics, NDE, and SHM Laboratory at the University of California San Diego. This technique has the potential to operate at high speeds and can be mounted on a regular train, thereby facilitating continuous condition monitoring of rails. This paper presents an improved version of the ultrasonic non-contact passive rail defect detection system with the introduction of a non-contact active acoustic source. The previous version of the system utilized air-coupled capacitive ultrasonic transducers in receiving-only mode to passively extract an impulse response function of a rail segment using rail-wheel interaction as the random source of excitation. The use of an active and controlled non-contact acoustic source is proposed for the improved system that aims to enhance the signal-to-noise ratio at the transducer array independent of variabilities of the wheel-induced excitation. Tests were conducted with various types of non-contact sources and source operating parameters to optimize the improved system. Results from field tests conducted by mounting the system on a train with testing speeds of 25 mph, 33 mph and 40 mph are presented.
Importance of Data Scaling for Various Machine Learning Models: A Case Study Based on Ionic Liquids for Processing Extra-Terrestrial Regolith
Authors: Rexhepi Fatlum , Banerjee Soumik 
Published: February 2024

Abstract
Lunar regolith is primarily composed of silicates and metal oxides, which are excellent in situ resources for metals as well as oxygen. Developing a technology for extracting metals from regolith would enable additive manufacturing of components for sustainable space exploration. Solvent-based digestion of regolith using Ionic Liquids (ILs) is a promising technique. Since experimental work on ILs is very expensive, this work is focused on leveraging Machine Learning (ML) algorithms to build statistical models to predict solubility. While prior effort employed optimal ML algorithm to predict solubility parameter for ILs, which is a descriptor of the solubility process, the selection of specific algorithms and pre-processing of data was not reported. To carefully study model selection, three different algorithms were tested. Emphasis was placed on preprocessing, where the importance of data scaling was analyzed. Finally, hyperparameter tuning was investigated within the range of the given search space. This analysis showed that when data preprocessing is done correctly models are not sensitive to different combinations of hyperparameters.
Parametric Study on the Nanoparticle Focusing in Thermophoresis Microfluidic Devices
Authors: Xue Guanyang , Caspar Justin , Cheng Xuanhong , Oztekin Alparslan 
Published: February 2024

Abstract
Three-dimensional computational fluid dynamics simulations were run to simulate the nanoparticle concentrating in thermophoresis microfluidic devices. Thermophoresis is a phenomenon where particles are driven by a temperature gradient. The microfluidic device utilizes thermophoretic force by applying 10 K temperature difference across the channel. The artificial transverse flow induced by slanted grooves is combined with the thermophoresis to concentrate nanoparticles. Following the experimental research, this study revisited the theory by applying the concept of circulation to evaluate the intensity of the transverse flow. Apart from the original experimental setup with 175 μm groove spacing, 25 μm and 75 μm setups were also simulated as comparison. The comparison shows that the peak circulation has no correlation between different groove spacing. The mass concentration accumulation was analyzed, and smaller spacing resulted in less fluctuation and more effective particle focusing. The averaged mass concentration from the outlet was processed, and in the best scenario, the 25 μm spacing design achieved 68% more concentration than the original 175 μm spacing design from the experiment.
Comparison of Biodiesel/Glycerin Separation by Gravitational Settling and Electrostatic Coagulation
Authors: Igbax Saanyol Ityokumbul , Swartling Daniel , Ahmed ElSawy , Idem Stephen 
Published: February 2024

Abstract
This paper compares the use of electrostatic coagulation and gravitational settling for efficient separation of biodiesel and its by-product glycerin, which were produced using raw materials such as waste vegetable oil and virgin canola oil. Titrations were performed to determine the free fatty acid (FFA) percentage and the optimal amount of catalyst to be used. The tests utilized an oil to methanol volume ratio of 6:1. Separation by gravity allowed each fluid to settle into different layers based on their respective densities. To reduce the separation time and improve the quality of biodiesel, the use of high voltage separation was investigated. A circuit rated at 1.5 kV and 1.5A was designed and constructed to impose a DC voltage potential across the biodiesel/glycerin mixture. The separation process was deemed to be complete when the electrical resistance across the load approached an asymptotic limiting value. In every instance the required time to achieve complete separation was recorded. For select cases considered in this paper, it was determined that use of electrostatic coagulation yielded significant reductions in the time required to fully separate the biodiesel and glycerin, as compared to gravitational settling.
Influence of Bondline Thickness on the Performance of Adhesive Joints Under Ballistic Peel Impact
Authors: Demir Gizem Derya , Yildiz Salih , Gursel Ali , Ikikardaslar Kerim Tuna , Delale Feridun 
Published: February 2024

Abstract
As structural adhesive technology advances, adhesive joints provide attractive advantages over conventional fastening methods. Since welding, riveting, and bolting may cause nonuniform stress distribution across the joint, and in many cases cannot be used to bond dissimilar materials such as composites to metals, adhesive joining may be considered as an alternative joining method. It is well known that the geometry of adhesive joints as well as their material properties and the adhesive thickness may affect their performance. In this study, an adhesive joint consisting of an aluminum back plate and a patch bonded by an epoxy is employed to investigate the influence of the bond thickness on the performance of adhesive joints under predominantly Mode I ballistic impact. A pressure gas gun is used for the dynamic test. High speed camera (Phantom V710) was used to record specimen behavior under ballistic peel impact tests. Frame rate of the high-speed camera to capture impacts was kept at 120,000 per second. The effect of bondline thicknesses (i.e., 0.005” (0.127 mm), 0.01” (0.254 mm), 0.015” (0.381 mm) on the adhesive joint performance were investigated. The results indicate that the adhesive joint with 0.01” mm bondline thickness performs better than those with 0.005” and 0.015” adhesive thickness. In addition to the experimental work, Finite Element Analysis is carried out to determine the mechanical properties of the joints by an inverse problem-solving technique.
Impact of Channel Shape and Process Parameters on Fluid Flow in Internal Channels of Material Extrusion Parts
Authors: Van Domelen Ryan , Wentz John , Shepard Thomas 
Published: February 2024

Abstract
The use of additive manufacturing (AM) techniques allows for the construction of internal flow conduits whose cross-sectional geometries can vary from the traditional circular, square, or rectangular passages made using more traditional manufacturing processes. These internal channels have seen use in conformal cooling of molds and other fluid transport processes that take advantage of the ability to generate internal features previously unable to be fabricated. In the creation of these channels some AM processes also run into issue through the requirement of support structures that must then be removed in post processing. While many experimental studies have shown the feasibility of fabricating and using these channels, there has been less study into the fluid dynamics at play within the channels that are a function of the AM process parameters. The impact of layer thickness, build orientation, and even channel shape is of interest to the design of parts that take advantage of the new capabilities. By modifying the cross-sectional shape, the velocity gradients and thus frictional pressure losses will also be modified, in addition to affecting support structure requirements in fabrication. This creates an opportunity for interesting research relating to cross-sectional shapes that may reduce energy losses within a pipe system as compared to a circular cross section. In material extrusion AM, print parameters such as layer height and print orientation relative to flow orientation can also impact the wall friction. In this study a variety of material extrusion pipes were printed in order to experimentally study the effect of cross-sectional shape (circle, diamond, teardrop), print layer thickness and hydraulic diameter on the pressure drop through the pipe with horizontal full-developed turbulent flows. The hydraulic diameters studied for each shape are 3.5 mm and 5 mm while the print layer thickness of 0.127 mm and 0.33 mm were used. Reynolds numbers ranged from 9200–61,300 with a test fluid of water. The results demonstrate a significant effect of channel shape with the diamond and circle profiles resulting in the lowest and highest pressure drops respectively for a given flow rate. As the desired internal channel shapes are a function of ability to fabricate overhanging shapes with and without support material, these results provide valuable insight to designers who desire to both reduce internal pressure drops and fabricate parts with internal channels in AM. This is specifically valuable as most processes are able to fabricate a diamond shape without support structure necessary, eliminating the need for support removal steps.