bluuebunny/crossref_metadata_2025_split huggingface dataset:
Innovative Thermal Management and Control to Surmount Challenges of Exploring Ocean Worlds on Europa and Enceladus
Authors: Hendricks Terry J. , Mueller Juergen , Furst Ben I. , Brandt Margarita N. , Hockman Benjamin J. , Berisford Daniel , Tarau Calin , Lee Kuan-Lin 
Published: February 2021

Abstract
Probes to penetrate the thick ice shells of our solar system’s Ocean Worlds have been studied for nearly 20 years, since scientific evidence strongly suggested a subsurface ocean on the Jupiter moon called Europa. There is keen scientific interest in exploring four significant themes on such proposed missions: 1) Geodynamics, 2) Geochemistry, 3) Habitability, and 4) Life Detection. The ice shells of Ocean Worlds are predicted to be up to 40 km thick; they exhibit extreme thermal environments, with ice temperatures from 100 K to 270 K, and extreme pressure environments from vacuum to 53 MPa. Jet Propulsion Laboratory has conducted a broad-look investigation of proposed mission concepts to Europa to identify the significant technology and operational challenges of Europa icepenetration. The thermal-mechanical system (TMS) of an ice penetration probe (IPP) mission concept designed to access the ocean of an icy moon using radioisotope thermoelectric generators for heat and power faces technological hurdles exacerbated by severe thermal and volume constraints. This study identified thermal management and control (TMC) challenges that are strongly linked to: ice penetration start-up, mobility and navigation in the ice, communications while in the ice sheet, and detecting and avoiding in-ice hazards. The major objectives of the TMC system are: 1) Absorb internal thermal energy from the IPP radioisotope power source, 2) Maintain liquid water conditions around the IPP at all times, 3) Manage and control thermal flows from probe nose to tail, and 4) Provide pressure containment for all internal probe components. This work discusses the baseline TMC system architecture and design developed to accomplish these objectives, and survive and transit the extreme ice thicknesses in pursuit of Icy/Ocean Worlds science goals. The proposed TMC system consisting of an internal pumped two-phase fluid loop “thermal bus” for thermal energy capture, variable conductance heat pipe system for passively adaptive thermal energy transport around the probe, and water jetting system for ice cutting is described and discussed. Critical testing performed to date is described.
Microstructural Enhancement and Performance of Additive Manufactured Titanium Alloy Grade 5 Composite Coatings
Authors: Fatoba O. S. , Akinlabi S. A. , Akinlabi E. T. , Naidoo L. C. , Adediran A. A. , Odebiyi O. S. 
Published: February 2021

Abstract
The surface integrity of Titanium alloy may be improved by surface modification, to expand its availability for more diverse industrial applications. Additive manufacturing is a commercially competitive manufacturing technique with the possibility of altering the entire perception of design and fabrication. The study experimentally investigates the effects that Ytterbium Laser System process parameters, such as laser power, powder feed rate and traverse speed, has on the resultant microstructure of Ti-6Al-4V grade 5 alloy. The deposition process was conducted employing a 3kW (CW) Ytterbium Laser System (YLS-2000-TR) machine, coaxial to the reinforcement powder. The laser scanning speed and power were varied between the intervals of 1–1.2 m/min and 900–1000 W. All other parameters kept constant were the rate of gas flow, the spot diameter, and the rate of powder flow. The microstructure was characterized by grain size and morphology by using Optical Microscopy (OM) and Scanning Electron Microscopy (SEM). During the DLMD process, the thermal histories induced in the process led to the promotion of the transformed α+β microstructure from the initial primary a microstructure; the growth and evolution of the distinct grain morphologies and stability of the alpha and beta structures upon increased and reduced structures. It was ascertained that by increasing the traverse speeds, the cooling rates increased, which resulted in the decrease in the width of the columnar grains.
Stiffness Degradation of Digital Polypropylene Under Fatigue Loading: Investigations via 3-Dimensional Polyjet Printed Coupons
Authors: Tomar Ravi Pratap Singh , Ulu Furkan I. , Kelkar Ajit , Mohan Ram V. 
Published: February 2021

Abstract
The utilization of additively manufactured parts is gaining popularity in functional applications. Polymer-based additive manufacturing (AM) parts are utilized in a variety of engineering applications for automotive, aerospace, and energy. AM printed parts are however newer class of materials, and structural performance of these materials is not fully understood completely, and very limited exists currently on precisely performance of Polyjet printed parts and associated digital materials under fatigue loading.
This paper investigates the stiffness degradation under tension-tension fatigue loading of digital polypropylene using homogenous 3-Dimensional test coupons formed using PolyJet printing. Homogeneous 3-Dimensional test configuration employed in the present study eliminates the process-induced limitations of traditional ASTM D638 2D fatigue test coupons for AM processed materials.
Fatigue data is analyzed to present an empirical model of effective elastic modulus and an analytical model of the accumulated damage state, as defined on the basis of stiffness degradation during cyclic loading. Further, the actual damage accumulation due to cyclic loading with the predicted model is compared. Modeling of the S-N diagram provides a better estimation of fatigue life and fatigue life modeling of AM printed test coupons and is obtained via linear regression analysis of experimental data with high correlation coefficient R2 (0.9971). The analytical model of the accumulated damage state is based on the stiffness degradation and is derived from the regression analysis of experimental data of stiffness degradation at different loading percentages assuming a polynomial of degree 4. Present study provides insight into the fatigue damage state and cyclic performance of digital polypropylene from Polyjet printing.
Experimental Optimization of Polymer Jetting Additive Manufacturing Process Using Taguchi Design
Authors: Weese Nathan A. , Rankin Chantz M. , Zhao Daguan , Hart Christoph , Quinlan Patrick , Day James B. , Salary Roozbeh (Ross) 
Published: February 2021

Abstract
Polymer jet printing (PJP) is a direct-write additive manufacturing process, emerging as a rapid high-resolution method particularly in the medical field for the fabrication of a wide spectrum of products, e.g., anatomical models, tissue scaffolds, implants, and prosthetics. PJP allows for non-contact multi-material deposition of functional polymer inks. The PJP process centers on simultaneous deposition of build and support photopolymer materials on a free surface, which are immediately cured in situ using a UV light source, allowing for solid-freeform fabrication. The PJP process is inherently complex, governed by a multitude of parameters as well as material-machine-process interactions, which collectively affect the functional properties of a fabricated structure. Consequently, physics-based characterization and optimization of the PJP process would be inevitable.
In this study, a new test standard was forwarded for the characterization of the mechanical properties of PJP-fabricated bone structures; the standard was designed on the basis of an X-ray p-CT scan of a femur bone in addition to the ASTM D638-14 standard. Furthermore, the Taguchi L8 orthogonal array design was utilized to investigate the effects of influential PJP process parameters on the mechanical properties of the bone structures, including Young’s modulus of elasticity, tensile strength, breaking strength, and ductility. The selected process parameters (each at two levels) were: (i) print direction, (ii) resolution factor, (iii) UV light intensity, and (iv) deposition head temperature. The mechanical properties of the femur bone structures were measured using a tensile testing machine.
The UV light intensity appeared as the most significant factor, influencing all the aforementioned mechanical properties, while the resolution factor was identified as an inconsequential factor. In addition, it was observed that the print direction and the head temperature significantly affected the breaking strength and the ductility, respectively. Overall, the results of this study pave the way for further investigation of the effects of the PJP parameters toward optimal fabrication of complex bone tissue scaffolds and implants with long-lasting functional characteristics.
Measurement of Thermal Conductivities of Bi2Te3 and Sb2Te3 Nano-Powders at Extreme Temperature and Strain
Authors: Xu Chenxin , Wang Brandon , Sneddon Emily , Marcovecchio Gianna , Ota Greg , Hunstein Karina , Zhang Xian 
Published: February 2021

Abstract
The Raman optothermal technique has been the most successful method for measurement of thermal conductivity of two dimensional (2D) materials, and was used to measure the thin films for the first time in this work. In this technique, a laser is focused at the center of a thin film and used to measure the peak position of a Raman-active mode. As the laser power is increased, the sample is heated which enables red-shift Raman mode due to thermal softening. Another comparison experiment is conducted by placing the samples on a heating platform and monitor the change of Raman-active mode peak position shift. Combining these two sections of experiments provide us the thermal modeling can then be used to extract the thermal conductivity from the measured shift rate. We have used a refined version of the optothermal Raman technique to study thermal conductivity of thin films of Bi2Te3 and Sb2Te3, at extreme temperatures and mechanical strains. It is the first thermal measurement on these two materials by Raman optothermal technique. This work also addresses several important issues in the measurement of thermal conductivity of thin films using Raman spectroscopy.
Microwave Induced Thermoacoustic Imaging With Multi-Pulse in Geological Application
Authors: Mao Xu , Liu Chang , Wang Chang , Heredia-Juesas Juan , Martinez-Lorenzo Jose Angel 
Published: February 2021

Abstract
The accurate and real-time monitoring of fluid flow in porous media can boost the prediction of mass transport and chemical reactions, which profoundly impacts the subsurface exploration and hydrocarbon extractions. Our preliminary effort has shown the efficacy of employing a thermoacoustic (TA) technology for imaging an immobile rock sample. The results support the applicability of making this methodology to move forward for imaging a dynamical process. But the real-time monitoring of fluid flow requires the target under test to excite TA signals with a higher signal-to-noise ratio (SNR), which will promise a sufficient image resolution with fewer necessary measurements or less averaged times, and then lead to a faster scan. It is proved that the excitation pulse is directly proportional to the microwave absorption rate, and thus determines the observability of the corresponding TA signals. Unfortunately, due to the thermal and stress confinements, a microsecond-width pulse envelope is greatly limited and is not sufficient for achieving a high SNR. Although a recently proposed Frequency Modulation Continuous Wave (FMCW) showed an improvement on SNR, it signifies a deficiency of the long-time irradiation and additional electronic disturbance especially at a high peak power. To address this issue, we propose a new excitation envelope with multi-pulses, to favor the coherent frequency-domain signaling method for optimizing the image reconstruction while shortening the total envelope duration than that of the FMCW. In the present paper, the TA sensing of a dry sandstone sample is presented, which efficiently enhances the SNR of TA signals and the image resolution, thus validating the appropriateness of the proposed multi-pulse envelope. The current study also promises a future possibility towards its application for dynamically exploring the underground flow transport.
Time−Motion Characteristics and Physiological Responses of Para-Footballers With Cerebral Palsy in Two Small-Sided Games and a Simulated Game
Authors: Henríquez Matías , Iturricastillo Aitor , González-Olguín Arturo , Herrera Felipe , Riquelme Sonny , Reina Raul 
Published: February 2021

This study compared physical performance in a group of international cerebral palsy football players during two formats of small-sided games (SSGs) and performance in a simulated game (SG) according to players’ sport classes (FT1, FT2, and FT3). Internal load (heart rate and rating of perceived exertion) and external load (total distance, distance covered at different velocities, maximum speed reached, acceleration, and deceleration) were obtained with global positioning system devices during two formats of SSGs (2-a-side/SSG2 and 4-a-side/SSG4) and an SG (7-a-side). SSG2 demands faster actions compared with SSG4/SG, and significant differences and large effect sizes were found in the distance covered in Speed Zones 5 (16.0−17.9 km/hr) and 6 (>18.0 km/hr; p < .05; , large). Lower moderate accelerations and decelerations per minute in SSG4/SG compared with SSG2 were also found (p < .01; , large). In the SSG2 task, the FT3 players reached maximum speeds, covered more distance at the highest intensities, and performed more moderate/high accelerations/decelerations and more sprints compared with FT1 and FT2 players (p < .05; −0.85 < dg < −4.64, large). The SSG2 task could be the best option for discriminating physical demands in important variables for cerebral palsy football performance between classes FT3 versus FT1/FT2.
Short-Term Psychological and Hormonal Effects of Virtual Reality Training on Chronic Low Back Pain in Soccer Players
Authors: Nambi Gopal , Abdelbasset Walid Kamal , Alsubaie Saud F. , Saleh Ayman K. , Verma Anju , Abdelaziz Mohamed A. , Alkathiry Abdulaziz A. 
Published: February 2021

Objective: To find the short-term psychological and hormonal effects of virtual reality training on chronic low back pain in American soccer players. Design, Setting, Participants: The 3-block random sampling method was used on 54 university American soccer players with chronic low back pain, and they were allocated into 3 groups: virtual reality training (VRT; n = 18), combined physical rehabilitation (n = 18), and control (n = 18) groups at University Hospital. They underwent different balance training exercises for 4 weeks. The participants and the therapist who is assessing the outcomes were blinded. Psychological (pain intensity and kinesiophobia) and hormonal (glucose, insulin, Homeostatic Model Assessment of Insulin Resistance, growth hormone, prolactin, adrenocorticotropic hormone, and cortisol) values were measured at baseline, after 4 weeks, and after 6 months. Results: The baseline demographic, psychological, and hormonal data between the VRT, combined physical rehabilitation, and control groups show no statistical difference (P ≥ .05). Four weeks following training, the VRT group shows more significant changes in pain intensity and kinesiophobia than the combined physical rehabilitation and control groups (P < .001), and the improvement was noted in the 6-month follow-up. All the hormonal variables (glucose, insulin, growth hormone, prolactin, adrenocorticotropic hormone, and cortisol) show significant changes at 4-week training (P < .001), except for the Homeostatic Model Assessment of Insulin Resistance (P = .075) between the 3 groups. At 6-month follow-up glucose, prolactin, adrenocorticotropic hormone, and cortisol show more significant difference in the VRT group than the other 2 groups (P < .001). At the same time, insulin (P = .694), Homeostatic Model Assessment of Insulin Resistance (P = .272), and growth hormone (P = .145) failed to show significant changes between the groups. Conclusion: Training through virtual reality is an effective treatment program when compared with conventional exercise training programs from a psychological and hormonal analysis perspective in American soccer players with chronic low back pain.
Biomechanics Differ for Individuals With Similar Self-Reported Characteristics of Patellofemoral Pain During a High-Demand Multiplanar Movement Task
Authors: Seeley Matthew K. , Son Seong Jun , Kim Hyunsoo , Ty Hopkins J. 
Published: February 2021

Context: Patellofemoral pain (PFP) is often categorized by researchers and clinicians using subjective self-reported PFP characteristics; however, this practice might mask important differences in movement biomechanics between PFP patients. Objective: To determine whether biomechanical differences exist during a high-demand multiplanar movement task for PFP patients with similar self-reported PFP characteristics but different quadriceps activation levels. Design: Cross-sectional design. Setting: Biomechanics laboratory. Participants: A total of 15 quadriceps deficient and 15 quadriceps functional (QF) PFP patients with similar self-reported PFP characteristics. Intervention: In total, 5 trials of a high-demand multiplanar land, cut, and jump movement task were performed. Main Outcome Measures: Biomechanics were compared at each percentile of the ground contact phase of the movement task (α = .05) between the quadriceps deficient and QF groups. Biomechanical variables included (1) whole-body center of mass, trunk, hip, knee, and ankle kinematics; (2) hip, knee, and ankle kinetics; and (3) ground reaction forces. Results: The QF patients exhibited increased ground reaction force, joint torque, and movement, relative to the quadriceps deficient patients. The QF patients exhibited: (1) up to 90, 60, and 35 N more vertical, posterior, and medial ground reaction force at various times of the ground contact phase; (2) up to 4° more knee flexion during ground contact and up to 4° more plantarflexion and hip extension during the latter parts of ground contact; and (3) up to 26, 21, and 48 N·m more plantarflexion, knee extension, and hip extension torque, respectively, at various times of ground contact. Conclusions: PFP patients with similar self-reported PFP characteristics exhibit different movement biomechanics, and these differences depend upon quadriceps activation levels. These differences are important because movement biomechanics affect injury risk and athletic performance. In addition, these biomechanical differences indicate that different therapeutic interventions may be needed for PFP patients with similar self-reported PFP characteristics.
Perspectives of Nigerian Athletes About Physiotherapy Services in Sports Injury Management: Implications for Rehabilitation
Authors: Odole Adesola C. , Agbomeji Olawale T. , Onyeso Ogochukwu K.K. , Ojo Joshua O. , Odunaiya Nse A. 
Published: February 2021

Background: Athletes’ perceptions toward physiotherapy services have an impact on their general attitude toward these services and their willingness to work together with physiotherapists for rehabilitation. The study investigated athletes’ perspectives of physiotherapy services in sports injury management. Methods: A mixed-study design of a cross-sectional survey that involved 178 conveniently sampled athletes and an explanatory qualitative study (8 purposively-selected athletes) was used. The authors assessed the participants’ knowledge and perception of physiotherapy services using the modified versions of the Athletes’ Level of Knowledge Questionnaire, Matsuno Athletes Perception Scale, and focus group discussion. The data were analyzed using chi-square, Spearman correlation at P ≤ .05, and deductive reasoning thematic analysis. Results: The age of the participants for the cross-sectional survey (131 men and 47 women) was 22.50 (7.51) years. Our results showed that the majority (91.6%) of them had adequate knowledge and (78.7%) positive perception about the role physiotherapists play in sports injury management. The participants’ knowledge of physiotherapy services had a significantly positive correlation with age (ρ = .12; P = .01), sporting years (ρ = .17; P = .02), and duration in sports council (ρ = .19; P = .01), while their perception showed a negative correlation with age (ρ = −.15; P = .05), sporting years (ρ = −.16; P = .03), and duration in sports council (ρ = −.08; P = .02). However, no significant correlation existed between the participants’ knowledge; perception and level of education; level of competition; type of sport; and type, nature, and severity of sport injury. Seven themes were generated from the focus group discussion. Conclusion: The participants reported adequate knowledge and a positive perception of physiotherapy services. The correlates of participants’ knowledge and perception of physiotherapy services are age, sporting years, and duration in the sports council. From the qualitative component of the study, the authors identified the need to provide more physiotherapy services to athletes and more facilities for physiotherapy services.
U.S. Physical Education Teacher Education Faculty Members’ Workplace Perceptions Across Gender and Institution Type
Authors: Richards K. Andrew R. , Graber Kim C. , Woods Amelia Mays , Ison Shelby E. , Killian Chad M. 
Published: February 2021

Purpose: To examine the workplace experience of physical education teacher educators while accounting for gender and institution type. Method: Participants included 286 U.S. faculty members (151 females and 135 males). Data were collected using an online survey that included measures of negative (i.e., marginalization, isolation, role stress, emotional exhaustion) and positive (i.e., perceived mattering, perceived organizational support) workplace experiences. Primary analyses began with a multivariate analysis of covariance followed up by univariate analyses of covariance to examine the differences in study variables based on gender and institution type. Results: Doctoral institution faculty members reported higher marginalization and lower perceived mattering and organizational support. Female faculty members reported higher role overload and emotional exhaustion. Discussion: Results highlight differences in the faculty experience across institution types as well as gender disparities. Recommendations are provided for improving the faculty experience as well as for future research in the area.