bluuebunny/crossref_metadata_2025_split huggingface dataset:
Variation Analysis of Carbon Fibre Reinforced Polymers Light Weight Aero Engine Parts
Authors: Fernström Vilma , Lööf Johan , Frampton Andrew , Brunnacker Lena , Wärmefjord Kristina , Söderberg Rikard 
Published: February 2023

Abstract
In this paper the focus is on variation analysis for composite CFRP (carbon fibre reinforced polymers) parts. A detailed study of possible sources of variation in manufacturing of CFRP parts is presented. Based on the variables identified a simulation chain on how to manage and simulate this variation is described. This paper also presents a logical approach to how a digital twin for a fully automated production line of compression molded CFRP parts can be built, and to investigate and quantify how much each individual variable contributes to the final variation in the component.
Improved Accuracy of Non-Contact Respiratory Function Measurement for Patients With Severe Motor and Intellectual Disabilities
Authors: Nakahama Takumi , Kosumi Remi , Sakamoto Ryota , Kato Norihiko , Yano Ken’ichi , Iwamoto Shotaro , Tsujioka Tomohiro , Takahashi Yuya , Yamakawa Noriko 
Published: February 2023

Abstract
Respiratory gas analyzers to measure functions such as ventilation volume respiratory rate are expensive, and patients with severe motor and intellectual disabilities (SMID) often remove the devices, increasing contact risk and making them difficult to use in institutions. We propose here an inexpensive, non-contact method of measuring respiratory function using the depth camera introduced in our previous study. The method includes an algorithm that differentiates between body tremors, and between movements peculiar to patients with SMID and those caused by respiration, while further detecting appropriate respiration. However, the previous region of interest (ROI) was limited to a simple rectangular area from the navel to the xiphoid process, and we did not compare measurements using the geometry of the thorax and the abdomen as the ROI. In this study, we performed non-contact respiratory measurement using the geometric shape of the upper body of patients as the ROI, and investigated the improvement of measurement accuracy when the ROI was set according to the individual patient’s body. The results indicated that the values from the new method approached those of the respiratory gas analyzer more closely than the conventional method, and its measurement performance was sufficient for respiratory rehabilitation evaluation. We also found that the measured respiratory signal correlated with the ventilation rate in respiration with large ventilation rate fluctuations, and that the respiratory rhythm abnormalities associated with ventilation rate changes could be measured by the respiratory rate per min and apnea time per min evaluation indices.
Constitutive Modeling of the Cross-Linked Polymers During the Trio-Aging Mechanism: Effects of Water, Oxygen, UV
Authors: Bahrololoumi Amir , Shaafaey Mamoon , Dargazany Roozbeh 
Published: February 2023

Abstract
The synergized effects of diverse environmental conditions such as humidity, temperature, UV, and oxygen, are considered through a generic model by combining the concepts of network alteration, hygrothermal, and Photo-thermo oxidation Models [1–4]. Hygrothermal and Photo-oxidation are considered dual aging mechanisms which are due to the synergized effects of moisture-oxygen, and UV-oxygen, respectively at elevated temperatures. Here Trio-aging is considered as the synergized effects of Hygrothermal, and Photo-oxidation which the main environmental elements involved in polymer degradation are oxygen, water, and UV radiation where each of which has a different micro-structural impact on the polymer matrix. While oxygen imposes chain scission and cross-link formation, water, and UV radiation mainly cause chain scission. Similar to our recent models, the dual network hypothesis of Topolosky is utilized and as a result, the strain energy of the polymer matrix is written in terms of two states namely unaged and infinity. The infinity state network, itself, is decomposed into three networks, namely brittle, flexible, and dead networks. While the brittle network models the cross-link formation as sub-structural phenomena, the flexible and dead networks are utilized to represent the cross-link reduction and chain scission. The contribution of these networks in the infinity state is based on the amount of relevant environmental elements. The model is developed for a domain with plenty of oxygen and holds true for a gradual aging process that happens in super-thin samples.
Investigation of Emission Reduction and Power Generation on Electrochemical Catalytic Membranes With the Addition of Perovskite Nanocrystals
Authors: Willsey Aliza M. , Fields Kassidy , Welles Thomas S. , Lin Hanjie , Zheng Weiwei , Ahn Jeongmin 
Published: February 2023

Abstract
With the depletion of fossil fuel resources, as well as increasing global temperatures, the interest in sustainable energy is on the rise. Currently, cars are a significant source of harmful emissions due to the use of internal combustion engines. Incomplete combustion byproducts are extremely harmful to the environment and the population, with links to acid rain, smog, and respiratory issues. While green energy solutions, such as electric vehicles, are being developed, the treatment of exhaust can also be an effective way to reduce the release of emissions into the atmosphere. It has been shown that a solid oxide fuel cell (SOFC) is able to break down emissions, even exceeding the capability of typical exhaust treatment methods. An investigation into the usage of an SOFC as an exhaust treatment material has found that the amplification of a signal generated across the cell has an even greater effect on emission reduction.
Here, the addition of cesium lead bromide (CsPbBr3) nanocrystals to the fuel cell is being investigated. The SOFC is tested as an exhaust treatment solution and as a power generation device in comparison to a typical SOFC without added CsPbBr3 nanocrystals. CsPbBr3 is a perovskite semiconductor, so it is expected to have an effect on the reactivity of the fuel cell. Investigating the effects of adding nanocrystals into a SOFC will lead to advancements in exhaust treatment systems as well as power generation systems. The work here will show a direct relationship between the quantity of nanocrystals contained in the SOFC to the emission reduction and power generation abilities of the SOFC.
Investigating the Effects of Solvents and Nanocomposites on Tailoring the Elastic Modulus of Piezoelectric Thin Film PVDF-TrFE
Authors: Kunwar Deepak , Hassan Md Mehadi , Jackson Nathan 
Published: February 2023

Abstract
Polyvinylidene Fluoride (PVDF) and its co-polymer derivatives have been extensively investigated as a thin film piezoelectric material due to its flexibility, which is desired for flexible sensors, wearable devices, tactile sensors, and low-frequency energy harvesters. Researchers are interested to enhance the piezoelectric response as well as the mechanical properties of PVDF and its co-polymer to enhance device performance. This work primarily investigates the solvents used to synthesize the polymer and their effect on the mechanical properties (hardness and elastic modulus) of thin-film co-polymer polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE). Various solvents with varying physicochemical properties were screened for the dissolution of PVDF-TrFE polymer to investigate the effect of solvents to tailor the key properties of the solvents that influences hardness, Young’s Modulus, flexibility, and the piezoelectric response. The hardness of the thin films was also affected by the addition of various nanocomposites. Hence, the hardness and the Young’s Modulus of the thin films with different solvents and ZnO nanocomposite particles was determined via nanoindentation. The thin films were characterized via X-ray diffraction (XRD), and quasi-static piezometer measurements and the thickness of the thin film was determined by a profilometer. The crystallinity of the thin films was enhanced via annealing at 125°C leading to a higher piezoelectric constant. This paper reports that the hardness and the Young’s Modulus of the thin films are highly dependent on the solvent’s physicochemical properties, dipole moment, and the nanocomposite concentration. Our observation revealed that the solvent with the highest dipole moment (HMPA) inherits the highest piezoelectric coefficient. This study demonstrates how manufacturing methods can affect the film’s mechanical and piezoelectric properties which are useful for researchers using PVDF in MEMS devices in the future.
Effect of Ageing and Environmental Conditions on Mechanical Properties of 3D Printed Parts
Authors: Lapuz Oginne Rashid , Vasilyan Hayk , Atatreh Saleh Ghalib , Alyammahi Mozah , Al Mheiri Ahmad Abdulla , Susantyoko Rahmat Agung 
Published: February 2023

Abstract
3D printing technology is often the go-to solution for rapid-prototyping thermoplastics. Parts can be created in record time with regards to the initial investment compared to the resources required in traditional fabrication methods such as injection molding. This has started a wave of manufacturers that are looking to scale their production with the use of 3D printing technology, as the parts have similar properties to their injection-molded counterparts.
As the advancement of 3D printing continues, to our knowledge, no studies have been conducted regarding the performance change of the part versus the use in inert-gas and vacuum antechamber environments. This study aims to demonstrate the effects of room, antechamber, dryer, and inert-gas environments with respect to the mechanical properties of 3D printed fused filament fabrication thermoplastics over time.
From the variation of the results that have been noticed on samples that were printed, the parts should not be utilized immediately, but rather they must be stored in a stable environment until the material properties are fully optimized. This would enable the designer to consider a risk factor to be applied that would account for expected changes in mechanical properties according to the environmental conditions for the intended application.
A Molecular Dynamics Study on the Piezoelectric Properties of Bulk ZnS and Nanobelts
Authors: Hijazi Iyad , Xie Rui , Houachissi Regis 
Published: February 2023

Abstract
A number of researchers have developed interatomic potentials for ZnS. The choice and reliability of a particular empirical ZnS potential is highly dependent on the application that the molecular mechanic simulation aims for, and therefore each of these potentials is designed to reproduce some specific ZnS properties. Therefore, in this work we proved the feasibility of using classical atomic simulations, namely molecular dynamics and molecular statics, to study the piezoelectric properties of bulk and nanobelts ZnS structures, by utilizing the core-shell atomic potential model. After conducting MD simulations of bulk and nanobelts ZnO piezoelectric constants, utilizing reliable ZnO core-shell potentials, we report the bulk ZnS piezoelectric constants calculated using three different classical interatomic core-shell ZnS potentials; the Wright and Jackson (1995) potential, the Wright and Gale (2004) potential, and the Namsani et al. (2015) potential. The simulation results showed that the Wright and Gale (2004) ZnS potential, which includes a four-body bonded term, is the most reliable potential to be used for large-scale atomic simulation of piezoelectric response of the bulk ZnS structures. Utilizing the Wright and Gale (2004) potential, we further studied the effect of size scale effect on the piezoelectric response of ZnS nanobelts by conduction molecular dynamics simulations for six ZnS nanobelts with length of 91.75 Å and transverse size of 22.94–42.06 Å. The results showed that, as with the ZnO nanobelts, the change of piezoelectric constant decreased with the increase of the size of the ZnS nanobelts structures.
Is the Blood Flow Laminar or Turbulent at Stenosed Coronary Artery?
Authors: Albadawi Muhamed , Abuouf Yasser , Elsagheer Samir , Sekiguchi Hidetoshi , Ookawara Shinichi , Ahmed Mahmoud 
Published: February 2023

Abstract
Coronary artery disease (CAD) is the abnormal contraction of heart supply blood vessel. This contraction in the blood vessels limits the flow of oxygenated blood to the heart. Thus, diagnosing its severity helps physicians to select the appropriate treatment plan. Most of the commonly diagnostic methods are qualitative. They depend on the physicians’ experience and judgement to specify the severity of the stenoses. Fractional flow reserve is one of the quantitative diagnostic tools used while coronary catheterization is being performed. Fractional flow reserve measures the pressure gradient from the proximal to the distal sides of a coronary artery stenosis; this helps in deciding whether the stenosis limits the oxygenated blood flow. Resent models of vascular hemodynamics consider physiologic blood flow to be laminar. Transition to turbulence is considered as a driving factor for numerous diseases such as stenosis and aneurysm. As the value of Reynolds number does not exceed 2000, the flow is laminar. Several researchers stated that the flow might be turbulent at critical Reynolds number value less than 2000.
Hence, the aim of this study is to investigate the most accurate turbulence flow model compared to the available experimental data. It is important to replicate the experimental model. Accordingly, the same non-Newtonian blood flow model and pulsatile flow boundary conditions were used. The stenosed simple geometry with a centered fractional flow reserve guidewire is constructed based on the same dimensions of the experimental setup. The numerical models were simulated with laminar flow and K-ε, and large eddy simulation (LES) turbulence modelling. The predicted results are compared with the actual available experimental measurements to investigate the most accurate numerical model of the blood flow in the stenosed coronary artery.
Based on the predicted results, pressure drop coefficient (CDP), Pressure recovery coefficient (CPR), and the pressure recovery factor η are investigated in the coronary stenosis with and without fractional flow reserve guidewire. For the severe 89% stenosis, it was found that the error in CDP before and during the guidewire insertion is small. The error in CDP before inserting the guidewire reached −7%, −7%, and −12% for laminar, turbulent K-ε, and LES models, respectively and −11%, −11%, and −4% for laminar, turbulent K-ε, and LES models, respectively during inserting the guidewire. Accordingly, it can be concluded that the laminar and LES modelling represent better performance in simulating the blood flow rather than the turbulence model.
Engagement State Definition and Detection in Education: A Review
Authors: Bocanumenth Aurora , Rendón-Vélez Elizabeth 
Published: February 2023

Abstract
Students’ level of positive learning-centered affective states, like engagement or flow state, has been proved to be strongly related to dropouts’ prevention, higher learning rate, and better student performance in their courses. Measuring users’ engagement state in a more effective and user-independent way may help create a better design of interactive applications and develop intelligent, more sophisticated, and adaptative study environments. The engagement reviews found in the literature go through psychological definitions but do not go deeper into the physiological and behavioral indicators of the state.
This review aims to analyze the current state of the art on engagement detection, to identify which are some of the most relevant physiological and behavioral indicators for engagement in students for its prediction during presential or online courses. A computer-aided systematic literature search was performed following the PRISMA methodology. A total of 24 articles were selected after removing duplicates and applying the selection criteria. These studies were analyzed to extract data relative to the physiological behavioral indicators, the classifier used, its’ accuracy, and the number of participants.
Indicators, such as leaning forward or backward and parasympathetic activation (such as HR, HRV, and GSR) have proven to be strongly related to students’ engagement states. The multimodal channel systems have been proven to have better performance, but the question of the best channel combination is still on the table. Different classification methods (SVM, RF, NB) have achieved high accuracy performance in experimental setups, but there are still challenges for real-life setups detection systems.
A Probabilistic Analysis in Vibration-Assisted Drilling to Measure Dynamic Behavior During Drilling and Understand Risk Factors
Authors: Marquez Eleazar , Garcia Samuel 
Published: February 2023

Abstract
In this paper, a mathematical representation is proposed to further understand the dynamic behavior and risk factors associated with vibration-assisted drilling (VAD) technology. The proposed Timoshenko beam model, which characterizes VAD technology, consists of two passive, counter-rotating coaxial rotors operating simultaneously, subjected to a stochastic excitation. In this regard, a finite element technique was incorporated to determine the physical parameters of the governing equation of motion, where the shear and rotary effects, as well as the gyroscopic couples generated perpendicular to the axis of rotation, were accounted for. Further, the relative velocity between the coaxial rotors was accounted in the equation of motion, which induced a modification on the stiffness and damping parameters. A fourth-order Runge-Kutta method was utilized to estimate the response and power spectra for soft and compact formations. Results indicated that resonance conditions due to gyroscopic effects manifest at soft and compact formations during drilling, however, at soft formations, the natural frequencies separated at lower RPMs, while at compact formations, higher RPMs were required to induce instabilities.
Optimizing the Curriculum in a Heating Ventilation and Air Conditioning Class With Realistic Labs, Projects and Interesting Realistic Problems to Enhance Learning
Authors: Larsen Kyle , Gharavi Hessam , Gerlick Robert , Michaelis Matthew 
Published: February 2023

Abstract
The primary purpose of a Heating Ventilation and Air Conditioning (HVAC) course is to provide the details and principles necessary to design a HVAC system. This encompasses the study of the many aspects of the various heating and air conditioning systems such as the moist air properties and conditioning processes, the comfort and health concerns, the cooling and heating loads and the system design including duct sizing, equipment and controls selection. This also includes the learning and using of software such as Trane Trace or Carrier HARP to calculate the heating and cooling loads for a commercial building and applying the applicable American Society of Heating Refrigeration and Air Conditioning Engineers (ASHRAE) standards. It is important to develop a method of dissecting a project to its essentials and solving it in a logical, organized manner. In our institution, we offer a one-quarter long HVAC class for the Mechanical Engineering and Mechanical Engineering Technology students. This is a comprehensive course which teaches our students the various aspects and topics of HVAC along with completing several realistic projects to help the students to learn real world applications of the design. This includes using the blueprints of a commercial building to design a HVAC system. Also included are labs, field trips, and guest speakers to help our students learn even more about HVAC. It is hoped that, after taking this course, students, if they choose, will be well prepared for a HVAC career. This paper will discuss and explore the many ways in which a HVAC class should be taught in order to make it a successful class. This includes teaching the basic principles and applying it to several real-world projects. One of the projects we have our students do at our university is to calculate the heating and cooling loads of a car dealer’s building which consists of an upstairs a front lobby, offices, kitchen, restrooms, and several car bays and to then recommend the equipment and controls necessary for the design. We also have the students complete a separate duct sizing project using both the equal friction and equal velocity methods. Further, we have several labs, including a refrigeration lab, calculating the coefficient of performances (COP) for various operating conditions. In addition, we explore alternate methods of energy savings such as ground source heat pumps, evaporative cooling combined with vapor compression refrigeration etc. Included in this course we have at least one guest speaker from ASHRAE as well as other professionals in the field. We also have our students visit our own universities’ steam and chilled water plant used for our heating and air conditioning as well as other relevant field trips.
A Novel Discrete, Mesoscale Modeling Framework for the Simulation of the Damaging and Fracturing Behavior of Composites
Authors: Salviato Marco , Phenisee Sean , Deleo Antonio , Pelessone Daniele , Flores Mark 
Published: February 2023

Abstract
A novel, discrete approach for the modeling of fiber reinforced composite materials which explicitly models the complex mesostructure is introduced. Fibers and fiber tows are represented as Timoshenko beam elements, and the mechanical behavior of the matrix is defined by vectorial constitutive laws expressed on facets obtained from the tessellation process in a tetrahedral mesh. For the mesoscale model generation, a computationally efficient, robust, and highly parallelized scheme is presented which is capable of generating laminates with fiber volume fractions higher than 60%.
Thanks to the explicit description, the constitutive laws of each constituent materials do not require complex mathematical equations and are physics-based with clearly defined material parameters.
To demonstrate the predictive capability of the model, uniaxial experiments are simulated for IM7/977-3 utilizing the novel framework. The investigated loading conditions include longitudinal tension/compression and transverse tension/compression. It is shown that the model is capable of capturing the strength of IM7/977-3 in both longitudinal and transverse directions. The damage mechanisms such as shear band formation and fiber micro-buckling are captured with the model using physics-based and clearly defined material parameters, thanks to the explicit description of fibers and matrix.