bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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.