bluuebunny/crossref_metadata_2025 huggingface dataset:
A New Tribo-Characteristic Improvement Technique by Ultra-Short Pulsed Laser Irradiation in PAO Oil
Authors: Liu Xiaoxu , Tanaka Yoshiki , Maegawa Satoru , Ono Shingo , Itoigawa Fumihiro
Published: February 2023

With the pursuit of high-precision and high-efficiency machining, laser-assisted machining technology has attracted more and more attention. Especially, ultra-short pulse laser irradiation can facilitate a quite high cooling rate and produce a local active space, which can make the surface modification realized without any removal. In this study, a novel tribo-characteristic improvement technology using ultra-short pulse laser irradiation in oil, with the hydrocarbon composition in oil as a carbon source, was proposed, to realize the surface modification of the workpiece in the same process with machining. Herein, a Ti-6Al-4V disk was irradiated using a pico-second laser in PAO oil under 4 different conditions with changed effective irradiated laser pulses and scanning modes. Besides the uniform laser irradiation, patterning irradiation was also conducted. From the results of the reciprocating friction tests, compared to those uniformed irradiated specimens, patterning irradiation processed surfaces show obviously more stable friction than the as-received metal surface. More importantly, much longer lifetime has been obtained, indicating the enhanced wear resistance. According to the investigation of hardness distribution, laser-induced thermal strain in the patterning irradiation method is considered to be an important factor of wear resistance improvement.
Multiscale Modeling of the Uptake of Hydrogen Chloride on Anodized Aluminum in Relevance to Spacecraft Fire Safety
Authors: Niehaus Justin , Mazumder Sandip
Published: February 2023

Fire safety is a critical component of space missions. An electrical fire within the spacecraft often produces gaseous hydrogen chloride (HCl) from the smoldering of wire insulation. These gases tend to stick to the interior materials of the spacecraft, which is often comprised of treated aluminum. Determining the rate of uptake for HCl by aluminum helps the safe design of the spacecraft to reduce catastrophic mission risk. Our previous studies showed that a one-step global reaction model for adsorption of HCl on aluminum is incapable of predicting the experimentally measured HCl uptake of anodized aluminum, compared to other treatments with thinner oxide layers. X-ray photoelectron spectroscopy revealed that aluminum chloride is found deep in the oxide layer of the anodized aluminum, implying that the transport of HCl within the oxide layer covering the aluminum surface must be considered. This work uses a multiscale modeling approach to predict the uptake of HCl. A pore model is developed wherein the HCl reacts with the aluminum oxide pore walls to create an aluminum chloride layer. The HCl then diffuses through that layer for further reaction, until the diffusion resistance grows too large, and the surface is said to be saturated. The pore model is then coupled with the reactor-scale model to predict overall HCl uptake. Results show that this new multiscale approach predicts the uptake of HCl far more accurately than previously used single-scale models.
Electrical Power Generation From Biogas Upgrading
Authors: Smith Morgan , Musgrove Zachary , Song Yuxin , Hu Hao , Duan Shawn
Published: February 2023

Great interest has been expressed in the harnessing of methane biogas from the decomposition of biowaste to combust in an electric generator to produce electricity. Biogas produced in this way is a mixture of methane gas, carbon dioxide, and hydrogen sulfide. To use this gas as a fuel for an electric generator, the gas mixture needs to be purified and dried to create a purer methane fuel in a process called upgrading. The application of such a technology has been posed as most effective in a situation where biowaste in the form of excrement, whether human or animal, is plentiful, and where conventional reliance on electric infrastructure is difficult. The Washington State Department of Transportation (WSDOT) has proposed one such application lies in the 47 safety rest areas possessed by the state. The goal of this project is to design and prototype a system which will take biowaste, in this case cow manure, and create a self-contained system which will collect and filter biogas to create methane fuel and supply this fuel to a generator modified to run on methane to produce electricity. This project successfully produced 8.5 pounds-per-square-inch of mixed biogas in an anaerobic digester and has created a filtration system to upgrade the gas for fuel in the electric generator. The mixed biogas is at a methane concentration of 100% of the lower-explosive-limit.
Nanosecond Laser Modification of Nickel-Titanium Based Shape Memory Alloys
Authors: Ma Jianfeng , Karim Mahmud Anjir , Jahan Muhammud P. , Shim Sally Jee Hyun , Lei Shuting
Published: February 2023

Nickel-Titanium based Shape Memory Alloys (Ni-Ti SMAs), a group of special advanced engineering materials, are gaining popularity in industrial engineering and biomedical engineering for their superior properties. for example, amazing shape memory effects (SME), high strength, excellent corrosion and wear resistance, pseudoelasticity, outstanding biocompatibility and biodegradability. Industrial applications of Nickel-Titanium based SMAs include phone antennas, sensors and actuators in aerospace industry, automotive industries, and robotics. Biomedical engineering applications of this group of SMAs include cardiovascular field, neurosurgical field, orthodontic and orthopedic field. The fact that this group of SMAs are very sensitive to stress and mechanical tension makes it very difficult to be machined using conventional manufacturing processes. As a result, many research studies have focused on improving the machinability of this SMA using non-traditional manufacturing processes. In this study, the Continuum Surelite Class III nanosecond laser system with 1064 nm wavelength and 5 nanosecond pulse width is used to modify the surface of a Nickel-Titanium based SMA. The effects of laser pulse energy level and lens-to-samples distance on the crater and slot forming are evaluated. Single shot mode of the laser system is used to generate craters, and totally six laser pulse energy levels are used. In addition, three lens-to-sample distance values are selected. These six energy levels are 0.053 J, 0.122 J, 0.296 J, 0.415 J, 0.526 J, and 0.662 J, respectively. The three different lens-to-sample distance values are 150 mm, 170 mm, and 190 mm, respectively. The focal length of the lens is 150 mm. Continuous shot mode of the laser system is used to machine slots on the Ni-Ti based SMA. For slot forming, two energy levels (0.296 J and 0.662 J) and two lens-to-sample distance values (150 mm and 190 mm) along with two different overlapping ratios (0.75 and 0.95) are used. A 3D surface profilometer is used to study the variation of crater depth with laser parameters. The scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS) analyses are used to investigate surface topography, surface modification, and laser-induced elemental composition on the Ni-Ti based SMA surfaces. The crater diameter and depth were found to vary with the laser energy levels and lens-to-sample distances. The surface finish and topography were also found to be influenced by the laser parameters. Finally, a suitable range of parameters for improved surface finish and targeted surface modification have been identified for nanosecond laser processing of Nickel-Titanium based SMA.
In-Process Intelligent Inspection of the Specimen Using Machine Vision
Authors: Mahor Adarsh , Yadav Ram Singar
Published: February 2023

Quality control is a crucial component of every manufacturing process. Quality production can be done by removing the defective pieces before reaching the packaging line. Several innovative systems have proven the use of visual input and advanced computer processing to fulfill various production goals during the last several years. Product inspection technologies based on machine vision are extensively researched to increase the quality of the product and save expenses. Computer vision and Deep learning have recently evolved, resulting in powerful data analysis tools with excellent scanning quality and resilience. Authors have attempted in this direction using such a method to detect flaws present in the dimensions of the bottles, which are traveling continually on the conveyor belt. Using pictures collected from the camera, the Yolov5 object detection method is used to localize the bottle in the image. Then, the image is passed for pre-processing, such as image cropping, image gray scaling, and smoothening of the image. The next step of this algorithm uses canny edge detection to detect edges present in the image. The image with detected edges is in the form of a binary image. All the pixels are extracted from this binary image in the form of an array. After performing some mathematical calculations on the output array, the dimensions of the bottle can be determined. The bottles were inspected for any faults in the dimensions in the manufacturing. Any bottles with flaws in the dimensions are discarded and separated from the manufactured bottles. The first step of the algorithm is object detection; here, the model has achieved the mean average precision of nearly 99.5 percent for the confidence threshold set to 50 percent to 95 percent. The following entire algorithm runs in less than 847 milliseconds. Such a high-speed algorithm allows manufacturers to increase and decrease the manufacturing speed according to their needs. This algorithm can check any shape of bottle, and this algorithm is not limited to bottles, but it can also work for any shape of object. As this model is only trained on the images of the bottles, the model cannot instantly work on the other objects, but one can use transfer learning to use this model on different object. This algorithm can also detect defects in multiple objects in the production line containing the manufacturing of multiple objects in the same line. The model can classify the objects from the production line and can also be used to classify them wherever required.
Impact of Rotor-Stator Rub-Impact on Post-Resonance Backward Whirl Excitation
Authors: Abdul Nasar Rafath , A. AL-Shudeifat Mohammad
Published: February 2023

It has been indicated in the literature to many factors that contribute to faults in rotor dynamical systems such as rubbing impact at stator-rotor contact. Accordingly, the appearance of rubbing impact is investigated here as one of the major factors that could excite the post-resonance backward whirl (Po-BW) phenomena in rotors. Therefore, the effect of rotor-stator rub impact on Po-BW excitation is numerically studied here with a Jeffcott rotor model. Accordingly, vertical and horizontal rotor configurations are considered here with rub-impact. The rubbing between the stator and the rotor is modeled by using both Heaviside function and the exact time calculation during the numerical simulation for comparison and to guarantee whirl results convergence. It is found that at a time step of order 10−6 in the numerical integration both Heaviside function and exact contact time calculations produce similar convergent results. In addition, the obtained numerical simulation results show that the stator-rotor rub-impact is found to excite the Po-BW and affects their recurrence and intensity. Accordingly, the current study provides a more insight to the impact of rotor-stator rubbing on Po-BW excitation. Therefore, the rotor-stator rub-impact is found to be one of the main factors that lead to excite the Po-BW during the rotor transient operation.
Numerical Simulation of Aggregation and Deformation of Red Blood Cells in Microchannels With Different Stenosis Severities
Authors: Elhanafy Ahmed , Abuouf Yasser , Elsagheer Samir , Ookawara Shinichi , Ahmed Mahmoud
Published: February 2023

Numerical simulation of cellular blood flow modeling has attracted many studies in the few recent years due to its importance in determining many macroscopic properties of blood. Additionally, the accurate modeling of blood flow, and hence the diagnosing of many cardiovascular diseases requires a detailed description of the dynamical behavior of individual cells. The aim of this study is to simulate the blood flow in the cellular level to have a better understanding and accurate modeling of blood flow in some cases that are not intensively examined in literature such as the dense suspension of flowing RBCs in microvessel with different degrees of stenosis. The present study is based on an open-source code, Hemocell for modeling blood flow in the cellular level. The lattice Boltzmann method coupled with the immersed boundary method are used to capture the cell deformation and the interaction between plasma forces and cell membrane. The distributions of the RBCs in both radial and axial directions are obtained. The deformation of the cells due to passing through the vessel especially the throat is studied for two cases of stenosis. It is found that the deformation of the cells at the center of the stenosis is higher than the deformation in other regions. Additionally, the increase of the stenosis degree increases the average deformation of the cells. It is observed that a longer time is required for the simulation in the case of 80 % reduction in the diameter.
Detection and Classification of Robotic Manipulator Anomalies Using MLSTM-FCN Models
Authors: Ma Yuliang , Grimmeisen Philipp , Morozov Andrey
Published: February 2023

Errors and failures occur inevitably in modern Cyber-Physical Systems (CPS) due to their structural variability and internal heterogeneity. This can cause economic losses or even hazardous accidents. Currently, deep learning-based anomaly detection methods, e.g., Transformer or LSTM-based detectors, have shown tremendous results in terms of anomaly detection and prevention. However, focusing solely on improving detection performance without classification and interpretation of the detected anomalies is not enough for many industrial scenarios. Instead of only reporting an anomaly, the detection results should be understandable and transparent for the users. The interpretability can provide some guidance and help to identify suitable countermeasures for different types of anomalies.

In this paper, we introduce a Multivariate Long Short Term Memory Fully Convolutional Network (MLSTM-FCN) for anomaly classification based on multivariate time-series data generated from industrial robotic manipulators. Specifically, we investigate several scenarios: no collision, collision with another manipulator, and manually injected sensor faults. We collect time-series data from the simulations of robotics arms using CoppeliaSim software. We feed these data into the MLSTM-FCN model and train it to be a multivariate time-series classifier. The paper presents the simulative case study results that show that the MLSTM-FCN model can efficiently classify different types of anomalies.
Combustion Characteristics of Single Isolated Fuel Droplets of Different Diesel-Biodiesel Blends Derived From Waste Vegetables Oil and Animal Fat
Authors: Parveg A. S. M. Sazzad , Ratner Albert
Published: February 2023

Increasing energy demands due to rapid industrialization and urbanization, stringent emission limits, and depleting sources of conventional fossil fuels urges the scientific community in search of renewable, reliable, cost-effective, and environmentally friendly alternative and sustainable options. Biodiesel has become a center of research initiatives to address these issues as a replacement or a supplement to conventional petroleum-based fossil fuels. Biodiesel derived from waste vegetables oil and animal fat is an interesting solution to face the concerns regarding fossil fuels as well as an effective and environmentally friendly way for the disposal of waste vegetable oil in addition to reusing it for energy production. In the transportation sector, typically biodiesel is used in blends with petroleum-based diesel, and the most common blends are B5 (up to 5% biodiesel) and B20 (up to 20% biodiesel). In this regard, current manuscripts report an experimental study on the combustion characteristics of single isolated fuel droplets of different diesel-biodiesel blends. Five different diesel-biodiesel blends named B5, B10, B15, B20, and B25 were used for the droplet combustion study. Neat diesel (B0) and biodiesel (B100) followed the d2-law of combustion while the blended fuel droplets deviate from the d2-law due to puffing and micro-explosion. Increased combustion rates were observed in blended fuel droplets and the highest increase of around 7% was observed for B15 droplets compared to B0 droplets. There were no significant differences in ignition delay between B0 and blended fuel droplets while B100 fuel droplets showed an increase in ignition delay up to 38% compared to B0 droplets. B10 and B15 fuel droplets showed significant decrease in droplet burning time. Highest decrease in droplet burning time was observed for B15 which was around 8% compared to B0 droplets.
Quantitative Detection of Delaminations in CFRP Composite Plate by Spatial-Frequency-Wavenumber Analysis Based on Laser Ultrasonic Guided Waves
Authors: Liu Zenghua , Liu Xiaoyu , Tian Jiuzhou
Published: February 2023

To comprehensively quantitative assessment of delamination location in CFRP composite plates, a Lamb wave spatial frequency wavenumber imaging method based on laser ultrasonic full-wavefield scanning inspection is proposed in this paper. For a CFRP composite plate specimen containing a delamination, a piezoelectric sensor is arranged to excite a sinusoidal modulation tone-burst signal. A laser transducer is used for pointwise reception to obtain Lamb waves full-wavefield data. Frequency domain filtering were performed on the wavefield signal to obtain single-mode wavefield. Short-space Fourier transform and instantaneous wavenumber analysis were applied to single-mode wavefield signal to obtain a distribution image of Lamb wave spatial wavenumber respectively. At the same time, the Lamb wave dispersion relation in CFRP composite plate is analyzed, and the delamination location is calculated based on this relationship. Finally, it can be seen from the imaging results that instantaneous wavenumber analysis can accurately locate the distance between the delamination and the laser scanning detection surface, but the short-space Fourier transform technology cannot identify the location of defects under the experimental parameters set in this paper.
Exploration in Using the Weibull Distribution for Characterizing Trends in Bearing Failure Operational Changes
Authors: Wescoat Ethan , Bradford Joshua D. , Krugh Matthew , Mears Laine
Published: February 2023

Remaining Useful Life (RUL) is critical to optimizing part life and reducing maintenance costs in a predictive maintenance strategy. Current methods of remaining useful life predictions are significantly dependent on operating conditions and time as input features. However, these features do not fully encompass the variability of real-world operating conditions and notably as the bearing nears failure. This work provides an improved failure representation by exploring the underlying data distribution parameters of a bearing failure dataset generated using the Purposeful Failure Methodology under varying operating conditions and then provides a comparison to the widely used NASA/IMS bearing run-to-failure dataset. Laboratory experiments utilized a bearing test stand to capture failure states for fatigue and contamination failure mode. The fatigue and contamination failure procession is compared to the failed bearings from the NASA Bearing dataset to examine similarities in the underlying data distribution between either dataset. A Weibull distribution is then fitted to both datasets. The resulting distributions exhibit similar trends, dependent on the damage stage. Based on the fitted parameters, a decreasing trend for the Weibull parameters was influenced by the changing speed in the engraving test case with similar trends to the NASA bearing dataset. The resulting understanding of the data distribution parameters will be used to improve the end of RUL calculation by describing the distribution fit that best determines the bearing life modification numbers.
Auxetic Metamaterial Development With Commercial Finite Element Tools
Authors: Corrado Casey , Skelton William , Angilella Alexander , Rosfjord Kristine
Published: February 2023

Metamaterials exhibit unique properties that are often not found in nature, making them advantageous in challenging engineering applications. These materials, however, are extremely difficult and time consuming to design, typically requiring custom algorithm development for a specific application. For metamaterials to be more readily created and implemented, an easily accessible design method that uses commercially available tools is needed. With the integration of optimization packages, commercially available finite element analysis software now presents an opportunity for the constrained design of metamaterials. This work investigates using topology optimization (TO) capabilities within commercial finite element analysis (FEA) software to create a methodology for targeted metamaterial design. This study focuses on auxetic materials, those exhibiting negative Poisson’s ratio, as an example case. An overview of the design process and topology optimization objectives, constraints, and boundary conditions will be provided, as well as a description of the challenges associated with utilizing a commercial FEA method.
Novel Thermal Coating for High-Speed Airplanes
Authors: Satapathy Abinash , Battu Lakshay , Watson Liam , Rajabi Nazanin , Park Jungkyu
Published: February 2023

In comparison to various other materials, carbon fiber, specifically carbon fiber reinforced polymers (CFRP) remains pre-eminent amongst other materials for use on aeronautical systems. Due to its high specific strength (strength-to-weight ratio), CFRP has been able to carry heavy loads while maintaining a lightweight build. This strength and weight efficiency has allowed for commercial airplanes such as the Airbus A350 and the Boeing-787 Dreamliner to greatly outperform common aluminum frame airplanes. Despite its extraordinary strength and light weight efficiency, when influenced by heat resulting from air resistance, CFRP is known to undergo serious degradation that would significantly decrease the effectiveness of the polymers. To prevent this degradation and maintain the strength of the CFRP, thermal protective layers (TPLs) are designed to shield the CFRP from heat exposure. This research is focused on the examination of the effectiveness of TPLs, that are hybrid compositions of epoxy resins and buckypaper (carbon nanotubes) for 3K 2 × 2 twill carbon-fiber, through experimental methods. Experimental thermal analysis of the CFRP is performed at 225 °C for hot plate testing and 650 °C for heat gun testing. The results show that the addition of buckypaper in the thermal protective layer seemed to detect nearly 48°C less heat on average of the four measured intervals in hot plate tests. From heat gun tests, moreover, it was clearly seen that the carbon fiber TPL that contains the epoxy and buckypaper is dominant in terms of heat dispersion. The anisotropic thermal transport property of nanostructured carbon is expected to spread heat accumulated in hot spots efficiently, preventing the heat from being propagated into the CFRP body material. In the near future, the authors will use analytical method and FEA simulations to explain this heat dissipation phenomena.
Preparing Generation Z: Beyond Technologies
Authors: Leão Celina , Alves Anabela C. , Soares Filomena , Silva Vinicius
Published: February 2023

Personal skills such as communication, leadership, teamwork, can be the key factor for differentiation in a technological career. Attending to this, the authors of this paper were motivated to propose a different course (or Curricular Unit, CU) to students of Higher Education level. In this way, this paper describes the aim, objectives, methodology in the creation of an elective CU, called “Preparing Generation Z: beyond technologies (Z-Tec)”. Z-Tec, lectured for the first time in the academic year of 2021–2022, allows student to acquire skills that promote a conscious and reflective transition to the job market, namely: to recognize the importance of career preparation and the skills needed for this preparation, to integrate enhancing strategies as a starting point for career management, to recognize such strategies as facilitators for personal, professional and social success, and to identify and critically apply tools that allow to objectively analyze and decide the professional future. Z-Tec puts on active learning methodologies based on practical exercises, debates, seminars and reflective activities. The results discussed are based on the students’ perceptions gathered at the beginning of each semester, on the several activities that students developed and on the students’ feedback gathered at the end of each semester. A total of 62 students from different areas of knowledge (Engineering, Economy, to Sociology and Public Administration) were positively engaged.
Performance Enhancement of New Concentrator Photovoltaic System Using Phase Change Material/Water Cooling Technique
Authors: Elsabahy Mohamed M. , Ahmed Mahmoud , Emam Mohamed
Published: February 2023

In the current study, a new hybrid heat sink combining phase change material and water cooling for low concentrator photovoltaic thermal management is introduced and analyzed. Unlike the previously introduced systems, the proposed one meets the requirements for practical applications, such as higher cooling efficiency over a longer period of time, reliability, low operating and maintenance costs, and the ability to store and reuse the system’s extracted thermal energy, thereby increasing total system efficiency. Furthermore, the new system combines the benefits of both active and passive thermal regulation systems, achieving a significant reduction in solar cell temperature when compared to passive systems and saving energy when compared to active systems. The study compares the performance of the developed new system with phase change material and water cooling to that of the conventional system with only phase change material cooling under various operating conditions. To that purpose, a comprehensive two-dimensional model of photovoltaic layers integrated with the hybrid phase change material-water based heat sink is developed. The uncooled PV model and the combined PV-PCM model are verified with experimental results in the literature. The model incorporates thermo-fluid models that account for phase transition phenomena and liquid flow in the heat sink domain, as well as a thermal model for the entire solar cell layers. The findings of this study show that the incorporation of phase change material and water cooling attains a remarkable reduction in the solar cell temperature with reasonable temperature uniformity and efficient thermal energy management. The reduction of average temperature and efficient thermal energy management leads to an increase in generated electrical energy and more thermal energy storage in the heat sink, both of which are reflected by higher cumulative electrical, thermal, and total efficiencies. The present findings can open doors for further research into merging the advantages of passive and active thermal regulation for low concentrator photovoltaic systems.
Accelerated Structural Design of Cellular Materials for Compressive Deformation Using a Machine-Learning
Authors: Song Jinlan , Takagi Aoi , Mitsuhashi Genki , Saito Kohei , Ogata Kazuma , Miyagawa Takeru , Yonezu Akio
Published: February 2023

It is well known that cellular materials (including porous materials) are widely observed in engineered and nature systems, because their mechanical performance is excellent, such as compressive deformation and energy absorption against impact loading. The mechanical response is significantly dependent on their inherent cellular structure, i.e., geometric arrangement pattern. A nonuniform arrangement could provide a significant variation of mechanical performance, and then material selection and geometrical designs are challenge. This study established machine-learning (ML) based framework to design geometrical arrangement (architecture) in cellular material to achieve better mechanical performance against uniaxial compression. Especially, we investigated peak force at plateau region and work of energy absorption until structural densification. Cellular material having various pattern of internal geometry was modeled using finite element method (FEM), and we simulated uniaxial deformation behavior, which was used as training data (teaching data) for machine learning method. This study employed neural network (NN) for machine learning method, which connects cellular geometric pattern with mechanical performance (force - displacement curve and peak force - work of energy absorption relationship). Our results showed that the proposed framework is capable of predicting the mechanical response of any given geometric pattern within the domain of our setting. Thus, it is useful to discover cellular structure in order to achieve desired mechanical response.
A Numerical Analysis on Taper Tube Hydroforging
Authors: Memon Shabbir , Nikhare Chetan P.
Published: February 2023

Typically, in tube forming, the end cross section is either expanded or reduced, or the tube is bent around a solid mandrel to achieve the desired shape. To reduce the friction generated between the tube and the physical tool like mandrel the tube hydroforming process was developed. The fluid was highly pressurized to expand the tube to a desired shape. The uniform thickness and thus better formability are achieved by replacing mandrel punch with hydraulic pressure in tube hydroforming. If the axial force to deform the tube is dominant in deforming the tube, then the process is termed as hydroforging. In this paper a two-step hydroforging process is discussed. With this two-step process, firstly the tube is bulged using the low fluid pressure and then axial force was applied to deform the tube axially and circumferentially while a constant internal fluid pressure was applied to prevent the buckling. During the first step a ramp pressure is used to provide a maximum bulging without necking, then in the next step a constant same peak ramp pressure or lower is applied while compressing the tube axially. In the previous study, a straight tube was used to study the pressure requirement, bulging, buckling and deformation mechanics to create a disc shape object. In this paper, a taper tube hydroforging was studied. The same two-step process was applied to bulge the tube first and then axially deform the tube. Two tube thicknesses and three angles were studied. The pressure requirement to bulge the tube and deform the tube was investigated. The deformation mechanics was analyzed. In addition, the stress, strain, and thickness distribution were studied and reported.
Development of an Improved Mathematical Representation Which Captures the Nonlinear Dynamic Behavior of a Drill-String Assembly
Authors: Marquez Eleazar
Published: February 2023

In this study, an improved mathematical representation of a drill-string assembly is developed to provide an alternative assessment on vibration irregularities proliferating downhole due to bit-rock interference. Lateral vibrations receive particular attention due to their high frequency content which alter the dynamic response of the drill-string, instigate casing damage, and impede optimal penetration rates. The response of the drill-string is captured by synthesizing compatible stationary bit excitations, via an auto-regressive digital filter, and implementing Monte Carlo simulation, while the power spectral density function is approximated to elucidate the dynamic characteristics during drilling. Formulating adequate physical parameters for the equation of motion implies incorporating a finite element technique, where the flexibility of the drill-string and elastic characteristics of the well-bore are accounted for. In conjunction with the stochastic nature of the excitation, the mathematical representation accounts for rig structural parameters, drilling fluid circulating within annulus/casing extremities, and a nonlinearity exhibited through a contact force generated between the well-bore and drill-string segment. To address the nature of the nonlinearity, the method of statistical linearization is incorporated to establish an equivalent linear system.
Manual Tasks Real-Time Ergonomic Evaluation for Collaborative Robotics
Authors: Lanzoni Daniel , Vitali Andrea , Regazzoni Daniele , Rizzi Caterina
Published: February 2023

In manufacturing, ergonomic and productivity benefits may result from combining the sensing and dexterity of the human workers with the strength of collaborative robots (cobots). Anyway, manual tasks requiring repetitive motion or working with robots can cause musculoskeletal disorders especially of the hands. In such a context, this paper proposes a novel solution that includes both a full body inertial system and a dedicated solution for hand tracking. This allows implementing the standard methods for assessing ergonomic indexes and to introduce new advanced task analyses based on gesture evaluation. The benefits reached by the integrated system for body and hand tracking can be exploited in the virtual prototyping of collaborative workstation in the manufacturing domain. Different software packages have been considered to model and simulate the collaboration between the operator and the cobot. In particular, Unity and ROS are used to develop the virtual scene and control the cobot behavior and the HTC Vive Head Mounted Display (HMD) to interact with the virtual environment. Physical ergonomics is evaluated by using both a full body suit (XSENS) and sensorized gloves (MANUS). The solution has been applied to the simulation of a virtual production line where the operator collaborates with a six-axis cobot (NIRYO ONE). Test tasks require the operator to move and manage different objects and tools by simulating different types of grasping. Real-time feedback about ergonomics, in terms of posture evaluation and alerts in case of critical condition, is shown to the operator as well as the automatic generation of reports for the post-process evaluation of the entire process. The results show how the use of these tools can be effective in the ergonomic evaluation of a collaborative robotic workstation which requires manual tasks.
A Neural Network-Augmented Bayesian Approach to Uncertain Parameter Estimation in Nonlinear Dynamic Systems
Authors: Zakeri Roja , Shankar Praveen
Published: February 2023

Many engineered and physical systems contain uncertain parameters and knowing their accurate value is essential to system analysis and design. In this paper, we propose a new approach that combines an artificial neural network with a Bayesian algorithm to achieve better computational efficiency in estimating an unknown parameter of a dynamic system. We utilize neural networks (NN) to start the Particle Markov Chain Monte Carlo (PMCMC) algorithm from a better initial guess of the unknown parameters which is closer to the target value of the parameter. The neural network that is trained on kinematic data are used to provide a rough initial estimate of the unknown parameter. This rough estimate is then used as the initial guess for the Particle Markov Chain Monte Carlo (PMCMC) method. The effectiveness of the new algorithm is first evaluated on a nonlinear benchmark problem — the Van der Pol oscillator. In estimating the damping factor using the NN estimate as the initial guess, the number of iterations required by the PMCMC is shown to reduce by 40% as compared to initializing the algorithm with a random guess. The new methodology was then applied to determine the unknown joint torques of a 7-DOF research robot based on the known joint position and velocities. Multiple neural networks based on different combinations of join position and velocities were trained and used to estimate the initial guess for the PMCMC algorithm. In each of the cases, there was a reduction in the number of iterations required for the PMCMC algorithm to converge as compared to a random initial guess with an average reduction around 30%.
Estimation of the Response, Power Spectra, and Whirling Patterns Generated From Mud Circulating Along the Annulus During Drilling Procedures: An Alternative Mathematical Representation via Finite Element Modelling
Authors: Marquez Eleazar
Published: February 2023

In this study, an alternative mathematical representation of a drill-string is proposed to provide an alternative assessment on BHA dynamic alterations. Lateral vibrations remain the focal point of drill-string breakdowns given their high frequency characterization and ability to deviate perforation trajectories from the subsurface target. In this paper, the proposed model consists of an anisotropic rotor subjected to distinct RPMs, an axial force, and a bidirectional harmonic excitation with specified amplitude and assorted duration to simulate annulus motion generated from the mud fluid. In this regard, Euler-Bernoulli beam theory was adopted to establish a complete MDOF mathematical expression and thus model an exclusive section of the BHA. Parameter identification implied incorporating a finite elements methodology, where the flexibility of the drill-string and elastic characteristics of the well-bore were accounted for. Particularly, a two-node element containing two displacements and two rotations per node was adopted to describe the rotor as a uniform, elastic beam. Thus, it is concluded from the proposed mathematical model that the harmonic excitation imposed along the annulus is introducing subharmonic frequencies and a potential (unmodeled) nonlinearity into the system.
Barbed Microneedle Design to Enhance Penetration and Retraction Forces Using Finite Element Modelling
Authors: Janardhana Ranjith D. , Cabanlong Mateus , Muttil Pavan , Jackson Nathan
Published: February 2023

Nature has optimized the structure of needles to reduce penetration force and increase retraction force as demonstrated by honeybee stingers, mosquitos and porcupines. Current microneedles typically consist of smooth sharp tips to reduce penetration forces, but these have poor retraction forces. This paper investigates the design of a bio-inspired barbed microneedle and its effects on insertion and retraction forces on the outer and inner layers of the skin. Various microneedle designs were investigated using COMSOL Multiphysics software to determine the impact of needle tip sharpness and barbed design on the forces. The interlocking of the microneedle with skin tissue was higher in the case of barbed-shaped microneedle compared to barbless needle resulting in a higher retraction force. Also, the size and geometry of the microneedle design affected the insertion and retraction forces. The development of a finite element model will allow us to further enhance the design of bio-inspired microneedles. This work also demonstrates the feasibility of using microfabrication techniques to manufacture various barbed microneedle designs using Su-8.
Vibrotactile Sleeve to Improve Music Enjoyment of Cochlear Implant Users
Authors: Yeganeh Nashmin , Makarov Ivan , Steinn Stefánsson Thors Snorri , Ásgeirsson Hafliði , Kristjánsson Árni , Unnþórsson Rúnar
Published: February 2023

This study presents a new design of a wearable vibrotactile device — a tactile sleeve consisting of three voice coil actuators (Model: Lofelt L5). The device was made within an R&D project aimed at developing a wearable for enhancing the music perception of cochlear implant recipients. The aim is to provide tactile stimulation in addition to the cochlear implant stimulation — generating an audio-tactile music experience. We also present the results of an experiment performed to investigate whether the sleeve can be used to identify songs from tactile stimulation and investigate the effects of different encodings. Five short music segments were used, and the tactile stimulation provided by each voice coil actuator conveyed song information (Bass or drum). Participants had intact hearing. At the beginning of the experiment, the participants listened to one song via headphones. Afterward, they were presented with various tactile encodings of the songs in random order. Their task was to identify the encoding of the song that was played. In this experiment, an investigation of the best combination of information from the bass versus drums was conducted. The results confirm that the sleeve can provide tactile stimulation that can be used to identify songs without audio. The results also provide insights into which encodings are most useful for conveying music.
A Comparative Study of Feasible Trajectories for an Under-Actuated Two-Link Bipedal Walking Robot With Hybrid Zero Dynamics Based Motion Planning
Authors: S. V. Shri Ishwaryaa , Kumar Akshay , Sangwan Vivek
Published: February 2023

Control of under-actuated bipedal walking robots has been an active area of research for many decades. Hybrid zero dynamics based motion planning is a technique very commonly used to plan trajectories for these robots. Exploring the solution space of optimal trajectories obtained through this method can potentially increase our understanding of bipedal walking by observing possible speeds, energy consumption etc. Very few studies are available with detailed solution space explorations of walking trajectories obtained through this method. This paper attempts to fill this gap by performing a hybrid zero dynamics based solution space exploration for an under-actuated two-link biped with a point mass at the hip as a proxy for the torso. The parameters of the biped chosen are similar to that of an average human. In addition, a comparison of the solutions obtained for different objective functions is carried out. Lastly, a non-dimensional analysis is done to identify if there are any dominant terms in the dynamics of the walking trajectories.
Development of a Small Project on Spray Combustion for an Undergraduate Fluid Dynamics Class
Authors: Palmore John
Published: February 2023

This work describes the development and evaluation of short project on spray combustion for a junior-level fluid dynamics course. A perennial question heard by educators in the United States is “When am I ever going to use this?” The standard format of most engineering courses involves lecturing students on various topics in mathematics and sciences related to their engineering discipline. Often students are not asked to apply the knowledge of said sciences in an engineering focused context until a capstone senior design course. In the mean time, students in freshman, sophomore, and junior courses become demotivated by the often dry nature of the theoretical focus. Evidence suggests that use of short projects and cases studies in the engineering classroom promotes motivation for the subject material. Some evidence also suggests that such motivation improves student learning outcomes. Accordingly, the development of such projects is important. This project focuses on topics that are often left out of the undergraduate engineering curriculum: combustion and two phase flows. These topics are major areas of interest for research in the automotive and aerospace industries, and are especially important for the design of engines for said vehicles. However, their discussion is often restricted to graduate courses if discussed at all. This project will introduce students to said topics in a novel context associated to applications in their field.

The project focuses on spray combustion because it is an important phenomenon in aviation gas turbine engines. The standard description of combustion in that context is as follows. First, the liquid fuel is injected into the engine where it is broken down into small droplets. The droplets vaporize, and the resulting fuel vapor mixes with the air around it. Combustion occurs for the fuel-air mixture, and energy is released as heat. For this project, students will engage with these processes at a cursory level using the tools of the fluid dynamics class. The project focuses on developing the students’ skills in control volume analysis, potential flows, and similitude. These topics roughly correspond to one of three major modules in the fluid dynamics course, and accordingly the project also serves as a mini-capstone for the module. The project divides students into small teams. Each team of students is tasked to design a combustor according to certain mission constraints which are varied between teams.

Project evaluation is performed by a survey of the students after the project is completed. The goal of the survey is to assess student opinions of the project including its effects on student motivation in the class and learning of the class material. This initial study focuses on gaining insight to improve the project design for future semesters.
Phonon Boltzmann Transport Equation Based Simulation of Frequency Domain Thermoreflectance Experiments
Authors: Saurav Siddharth , Mazumder Sandip
Published: February 2023

The Boltzmann Transport equation (BTE) was solved numerically in cylindrical coordinates and in time domain to simulate a Frequency Domain Thermo-Reflectance (FDTR) experiment. First, a parallel phonon BTE solver that accounts for all phonon modes, frequencies, and polarizations was developed and tested. The solver employs the finite-volume method (FVM) for discretization of physical space, and the finite-angle method (FAM) for discretization of angular space. The solution was advanced in time using explicit time marching. The simulations were carried out in time domain and band-based parallelization of the BTE solver was implemented. The phase lag between the temperature averaged over the probed region of the transducer and the modulated laser pump signal was extracted for a pump laser modulation frequency ranging from 20–200 MHz. It was found that with the relaxation time scales used in the present study, the computed phase lag is underpredicted when compared to experimental data, especially at smaller modulation frequencies. The challenges in solving the BTE for such applications are highlighted.
Evaluation of Head Injury Patterns and Risk Mitigation Strategies Associated With Falls From Playground Equipment
Authors: Guttag Mark , Kennedy Eugenia , George Juff , Pasquesi Stephanie
Published: February 2023

Playgrounds have a number of key design elements intended to protect children from serious injuries. The U.S. Consumer Product Safety Commission (CPSC) estimated that most playground equipment-related injuries occurred when a child fell from the equipment onto the ground [1].

It was estimated that in 1999 approximately 206,000 playground equipment-related injuries required a hospital emergency room visit [2]. Specifically, for children under five years of age there were 29.1 injuries per 10,000 children and for children ages 5 to 14 years old there were 34.8 injuries per 10,000 children. At the time, about half of the injuries on public equipment occurred on playground climbing equipment [2].

With the recent heightened public focus on children’s head injuries, this paper will review the National Electronic Injury Surveillance System (NEISS) data to better understand the injury trends over time, quantify risks associated with playground equipment usage and discuss the design features intended to mitigate these hazards. The analysis is restricted to children ages 2 to 12 years of age who were injured during the timeframe 2000 to 2020. The focus of the analysis will be head injuries resulting from falls associated with playground climbing equipment. The severity of injuries will also be discussed. Further, the identified head injury characteristics will be evaluated relative to the performance requirements outlined in the industry standards and CPSC guidelines.