bluuebunny/crossref_metadata_2025 huggingface dataset:
External Validation of a Predictive Score for Fracture-Related Infections in Orthopedic Trauma Surgery
Authors: Campbell Tanner , Kirwan Mateo , Behzadpour Vafa , Langvardt Tanner , Dallman Johnathan , Huang Yanjie , Castillo Renan C. , O'Hara Nathan N. , O'Toole Robert V. , Wise Brent
Published: August 2024

Background:

The purpose of this study was to externally validate a predictive score for fracture-related infections, establishing generalizability for absolute and relative risk of infection in the setting of orthopedic fracture surgery.

Materials and Methods:

This was a retrospective, case-control study performed at a level I academic trauma center that included 147 patients with fracture-related infection in the study group and 300 control patients. We analyzed the same 8 independent predictors of fracture-related infection cited by a previous study. We then used the area under the receiver operating characteristics curve (AUC) to compare the derivation and validation cohorts. The validation and derivation cohorts were then compared by grouping patients into 4 strata of Wise score groups. This allowed for comparison of AUC and risk of fracture-related infection in our institution with those in the previously studied institution.

Results:

The resulting data yielded an AUC (0.74) nearly identical to that of the previously studied institution. It was also found that the relative risk of infection correlated with the Wise score in the same way the initial model did with the absolute risks being similar.

Conclusion:

The previous predictive model was externally validated and shown to be generalizable to a different patient population. The relative risk of a fracture-related infection can be determined using this scoring model preoperatively with the goal of aiding in patient counseling and surgical decision-making, giving a quantitative value to patient risk factors. [
Orthopedics
. 2024;47(5):e268–e272.]
The multi-parameter estimation of discrete distribution without closed-form solutions by the US algorithm
Authors: Ouyang Yuanhang , Yan Ruyun , Shi Jianhua
Published: August 2024

Strong and steady convergence characterizes the upper-crossing/solution (US) algorithm, which is an effective method for identifying roots of a complicated nonlinear equation $ h(\theta) = 0 $. Only the case where one parameter of a distribution function can be directly specified by another parameter is taken into account by the research that is currently available. However, whether this approach can be applied in multi-parameter scenarios where one parameter cannot be clearly represented by the other is an issue deserving of more investigation. In order to extend the applicability of the US algorithm, this article used the Type Ⅰ discrete Weibull distribution with two parameters as an example. It then combined the US algorithm with the first-derivative lower bound (FLB) function method to estimate the complex situation where two parameters cannot be expressed as each other. Simulation studies and empirical analysis demonstrated that the US algorithm performs more accurately and steadily than the traditional Newton method.
An accelerated adaptive two-step Levenberg–Marquardt method with the modified Metropolis criterion
Authors: Zhu Dingyu , Yang Yueting , Cao Mingyuan
Published: August 2024

In this paper, aiming at the nonlinear equations, a new two-step Levenberg–Marquardt method was proposed. We presented a new Levenberg–Marquardt parameter to obtain the trial step. A new modified Metropolis criterion was used to adjust the upper bound of the approximate step. The convergence of the method was analyzed under the H$ \ddot{\rm o} $lderian local error bound condition and the H$ \ddot\rm o $lderian continuity of the Jacobian. Numerical experiments showed that the new algorithm is effective and competitive in the numbers of functions, Jacobian evaluations and iterations.
Solving the time fractional q-deformed tanh-Gordon equation: A theoretical analysis using controlled Picard's transform method
Authors: Ali Khalid K. , Mohamed Mohamed S. , Alharbi Weam G. , Maneea M.
Published: August 2024

This paper presented the formulation and solution of the time fractional q-deformed tanh-Gordon equation, a new extension to the traditional tanh-Gordon equation using fractional calculus, and a q-deformation parameter. This extension aimed to better model physical systems with violated symmetries. The approach taken involved the controlled Picard method combined with the Laplace transform technique and the Caputo fractional derivative to find solutions to this equation. Our results indicated that the method was effective and highlighted our approach in addressing this equation. We explored both the existence and the uniqueness of the solution, and included various 2D and 3D graphs to illustrate how different parameters affect the solution's behavior. This work aimed to contribute to the theoretical framework of mathematical physics and has potential applications across multiple interdisciplinary fields.
Industry-specific effects of economic policy uncertainty on stock market volatility: A GARCH-MIDAS approach
Authors: Msomi Simiso , Kunjal Damien
Published: August 2024

In recent years, monetary authorities have used unconventional monetary policy practices to stabilize economies. As a result, economic policy uncertainties have increased; subsequently, this has created fragilities in financial markets and exposed investors to greater levels of investment risk. However, recent literature suggests that volatility dynamics differ across industries, with some industries having hedging capabilities. On this basis, this study's objective is to explore the impact of economic policy uncertainty (EPU) on the volatility of different industries in South Africa. The GARCH-MIDAS approach was employed to achieve this objective, and nine industry-specific indices were evaluated from 3 January 2000 to 29 December 2023. The industry-specific analysis revealed that EPU has a negative relationship with the volatility in the following four industries: consumer discretionary, financials, health care, and technology. However, a positive relationship was found for the basic materials industry, while no significant effect was reported for consumer staples, energy, industrials, and telecommunications. Overall, these findings indicate that the EPU effects are asymmetric across industries and, therefore, it follows that the impact of EPU should be accounted for when making asset allocation choices.
Movement and Growth of Translocated Coastrange Sculpin and Prickly Sculpin in Two Urban Lake Washington Tributaries, Washington
Authors: Tabor Roger A. , Johnson Jeffery R. , Peters Roger J. , Olden Julian D.
Published: August 2024

Urbanization and other forms of land conversion have led to dramatic changes in freshwater ecosystems. We assessed the movement and growth of Coastrange Sculpin Cottus aleuticus and Prickly Sculpin C. asper, two species that are considered migratory based on their potamodromous and amphidromous life history strategies. We determined critical aspects of their ecology in two urban streams where they are rare or absent. Both species were collected near the stream mouth or in Lake Washington, implanted with passive integrated transponder (PIT) tags, and translocated to an upper stream reach where their downstream movements and growth were monitored. Detections at stationary antennas indicated most downstream movements occurred from January to April, as has been observed in other Pacific Northwest systems. About 80% of the translocated sculpins remained in the study reach for at least 2 months before moving downstream and 10% remained more than a year. Smaller Prickly Sculpin generally remained in the study reach longer than larger Prickly Sculpin; however, no size effect was observed for Coastrange Sculpin. Most downstream movements occurred during low and moderate streamflow levels during each season for both streams; however, downstream movements occurred at relatively higher flows compared to the cumulative distribution of observed flows during most seasons. Both species appeared to grow well in the study streams; although, Prickly Sculpin growth rates were approximately double that of Coastrange Sculpin. Coastrange Sculpin often inhabit riffles where increased fine sediments and embeddedness from urbanization may impact them more than Prickly Sculpin, which typically inhabit pools. The overall survival and growth of both species in the two highly urbanized streams was better than expected. This study suggests that the lack of sculpins in some urban streams may be a result of stream barriers to movement rather than poor habitat conditions.
The Library Amid an Epistemic Storm
Authors: Chisita Collence Takaingenhamo
Published: August 2024

Modern academic libraries in Africa have their roots in colonialism. As such, they have not evolved to adjust to calls for providing services that resonate with balanced epistemic experiences in multicultural communities. The lack of library services that incorporate modern and indigenous knowledge services raises concerns about whether such institutions have no interest in leveraging indigenous knowledge as an alternative epistemology that provides solutions to contemporary problems. The chapter explores the extent to which libraries have incorporated indigenous knowledge. The study will use a qualitative methodology to understudy the position of libraries toward indigenous knowledge. It will explore how epistemic aberration can be resolved for the benefit of Indigenous people.
The relationship between emotional regulation and sports performance: A systematic review
Authors: Villas Boas Junior Marcelo , Ucha Francisco García , Souza Vania Hernandes de , Manzini Mateus , Corrêa Mariana de Freitas , Angelo Daniela Lopes , Corcuera-Bustamante Santiago , Reyes-Bossio Mario , Viveiros Luís , Brandão Regina
Published: August 2024

The aim of the study was to investigate, through a systematic review of the literature, the relationship between athletes’ emotional regulation in performance or competition. The strategy (SPIDER) was used, and the keywords were used according to the respective vocabulary restricted to each database (PubMed, SciElo, Portal BVS, SPORTDiscus, PsycNET). The Boolean operators AND and OR were used, and 2 inclusion and 4 exclusion criteria were adopted. This systematic review is registered on the PROSPERO platform under the ID CRD42020216250. For analysis and qualitative synthesis, 10 studies were included, and 16 modalities were identified with a sample of 434 athletes, 84.1% male and 15.9% female. Regarding the results, we can observe that the relationship between regulation and sports performance lies in the interaction of environmental, social, and psychological factors, which can trigger positive and negative emotions that impact sports performance. Moreover, it is worth noting that the studies have verified the phenomenon of regulation of emotions through various instruments and strategies, thus demonstrating the heterogeneity of the studies included in this review. No longitudinal studies were observed; however, emotions and regulation of emotions can undergo alterations due to the sporting moment and the degree of importance of the competition.
Festival quality, value, and sports environment affecting students’ satisfaction and loyalty: basis for continuous extra-curricular activity offering
Authors: Lobo Joseph , Varona Diana
Published: August 2024

Extracurricular events like the sports festival, where students can demonstrate their skills in organized sports and recreation, are essential in higher education. Students can also develop leadership, camaraderie, and sportsmanship while competing in each game. Sports festivals encourage students to be active and healthy through games. This study examined students' perceptions of quality, value, and sports environment, which affects their satisfaction and loyalty to extracurricular activities. Most importantly, the study will help the department and administration decide if sports festivals can be held regularly to enhance campus physical culture. The respondents for this study are students from a local college who participated in the recent Sports Festival conducted by the students and department. The Festival Satisfaction Survey (FSS) was modified to meet the current study by eliminating the souvenir aspect. Additionally, the Youth Sport Environment Questionnaire (YSEQ) was employed to include the two components in the former measure as extra constructs. A one-way ANOVA/Kruskal-Wallis H was performed to investigate FS and FL differences based on demographics. Spearman Rho’s analysis described variable relationships. Finally, multiple regression was used to assess if QVSE influence satisfaction and loyalty. Based on the findings, festival satisfaction and loyalty did not differ between groups (excluding year level group). Also, QVSE has a significant relationship with FS and FL. Lastly, QVSE has a direct influence on FS and FL. To give students a meaningful experience and develop and preserve campus physical culture, the department and administration may regularly offer activities like the sports festival.
The prevalence of exercise-induced bronchoconstriction in non-asthmatic swimmers: A systematic review and meta-analysis
Authors: Dutra Lima Manuella Jessyca , Dos Santos Vianna Angelica , Costa Julia Vianna de França , Paiva Natalia Santana
Published: August 2024

Objective: To evaluate the prevalence of exercise-induced bronchoconstriction (EIB) in non-asthmatic swimmers. Methods: We searched BVS/LILACS, MEDLINE/PubMed, Web of Science, Scopus, SPORTDiscus databases, and two repositories (BDTD and OATD) up to July 2023. A combination of MeSH descriptors and text words were used. We selected original studies reporting cases of EIB diagnosed by objective test in non-asthmatic swimmers. We assessed the quality of the included studies for bias with Joanna Briggs checklist for prevalence, and conducted random-effects meta-analyses with planned subgroup analysis. Results: This review retrieved 33 studies (700 non-asthmatics swimmers, 250 cases of EIB). The EIB prevalence was 34% (95% CI: 25-45%) with a significant heterogeneity (I2 = 68%), which was partially explained by the subgroup analysis for diagnostic method used. The methacholine test showed a higher prevalence (51%, 95% CI: 43-59%) with a low heterogeneity (I2 = 28%). Only three studies (90.1%) were considered as low risk of bias, while the remaining 30 (90.9%), as moderate. The results indicate that non-asthmatic swimmers have an expressive prevalence of EIB, especially when performing methacholine test. Conclusion: The better understanding of the prevalence of EIB among non-asthmatic swimmers, estimated in 34% in this review, should be considered a warning to professionals involved in training and health policymakers. Public health interventions for prevention are required. Also, the substantial heterogeneity between studies highlights the need for better designed studies.
Análise do equilíbrio em idosas obesas e não obesas praticantes de um programa de atividades físicas regulares
Authors: Passinato Ivo Leandro de Melo , Oliveria Gustavo Henrique de , Beck Higor Barbosa , Costa Carla Eloise , Porto Fernanda Errero , Deprá Pedro Paulo , Lopes Wendell Arthur
Published: August 2024

O objetivo foi analisar o equilíbrio em idosas obesas e não obesas praticantes de um programa de atividades físicas regulares. Trata-se de um estudo descritivo, com delineamento transversal. A amostra foi composta por 32 idosas, com idades entre 60 e 75 anos, alocadas em dois grupos, de acordo com o estado nutricional. Para a análise do equilíbrio foi utilizada a plataforma de força, na qual foi obtido o comportamento do centro de pressão (COP), na posição bipodal, nas condições olhos abertos e olhos fechados, e monopedal, com a perna direita e perna esquerda. O valor de significância adotado foi de 5%. Os grupos foram homogêneos quanto a idade e estatura. Não houve diferença significativa nos deslocamentos anteroposterior (AP) e médio-lateral (ML) do COP tanto na condição olhos aberto como olhos fechados entre idosas obesas e não obesas. Quanto à velocidade do COP, verificou-se que as idosas não obesas apresentaram maior velocidade tanto na condição de olhos abertos (p<0,001) como olhos fechados (p<0,05) quando comparadas as idosas obesas. Não houve diferença significativa na posição monopedal em nenhuma das variáveis analisadas entre idosas obesas e não obesas. Conclui-se que a obesidade afetou positivamente o equilíbrio de idosas praticantes de atividades físicas regulares na condição bipodal e não comprometeu o equilíbrio na posição monopedal.
Relação da ansiedade e da autoestima com o transtorno do desenvolvimento da coordenação
Authors: Borsatto Roberta Crepaldi , Alves Catarina Messias , Catabriga Lorena Mota , Souza Vânia de Fátima Matias de , Lopes Vieira José Luiz , Ferreira Luciana
Published: August 2024

Baixos níveis de competência em habilidades motoras apresentam como consequência o surgimento do Transtorno do Desenvolvimento da Coordenação (TDC) e, as dificuldades motoras tendem a interferir negativamente em aspectos socioemocionais podendo resultar em ansiedade e baixa autoestima. O presente estudo analisou a relação entre competência motora, ansiedade e autoestima. Participaram do estudo 138 estudantes, com faixa etária de 10 a 15 anos, que   responderam a três questionários, o Adolescent Motor Competence Questionnaire (AMCQ), a Escala de Autoestima de Rosenberg e a versão em português do Inventário de Ansiedade Traço-Estado (IDATE). Além dos estudantes, participaram do estudo 127 pais que responderam ao questionário de Transtorno do Desenvolvimento da Coordenação - Brasil (DCDQ). Para análise foi utilizada a estatística descritiva, na comparação entre grupos utilizou-se o Teste t de Student e para a correlação, utilizou-se o teste Correlação de Pearson e o Qui-quadrado, respectivamente. Os resultados indicaram que quanto maior a competência motora percebida, menor os níveis de ansiedade e maiores os níveis de autoestima. Dessa forma, conclui-se que escolares com suspeita de TDC por apresentarem baixa competência motora percebida, os níveis de ansiedade são maiores e o níveis de autoestima menores, comparados com os escolares sem suspeita de TDC.
Adventure pedagogical model as a growing concept in physical activity
Authors: Caballero-Blanco Pablo , Herrera-Pombero Carlos , Bento Pedro
Published: August 2024

A relevância dos modelos pedagógicos na atividade física tem vindo a aumentar nas últimas décadas. Estes são entendidos como as estruturas nas quais os professores podem organizar os diferentes elementos envolvidos no processo de ensino-aprendizagem, a fim de alcançar os resultados de aprendizagem esperados. Entre os vários modelos pedagógicos existentes, distinguem-se os que têm uma trajetória mais consolidada e os chamados modelos em ascenso que procuram novos paradigmas de ensino-aprendizagem centrados sobretudo no ensino ativo. Entre os modelos em ascenso, encontramos a Pedagogia da Aventura (PA), que se baseia nos modelos da educação através da aventura (uma abordagem centrada no desafio e na aventura como componente essencial das atividades) e do Outdoor Education, que tem por base as atividades no ambiente natural. Desta forma, a Pedagogia da Aventura, procura através do desafio e das possibilidades oferecidas pelo meio natural, contribuir para o processo de humanização dos participantes através do desenvolvimento pessoal e social, enquanto promove o desenvolvimento de competências técnicas específicas para atividades físicas no meio natural. Este artigo descreve a relevância atual do modelo da Pedagogia da Aventura, as suas componentes-chave e as suas possibilidades como modelo emergente na procura do desenvolvimento integral dos participantes em atividades físico-desportivas.
Physical activity of children transitioning from kindegarten to primary school: A pilot study
Authors: Culková Dita , Dušková Veronika
Published: August 2024

This research focuses on the decrease in PA as children transition from kindergarten to primary school, underscoring the importance of supportive school environments and parental influence in maintaining PA. The study observed 43 children initially in preschool and later in school settings, measuring their physical activity (PA) during school days using digital pedometers and two self-constructed questionnaires. The pilot study used variance inflation factor analysis, principal component analysis, multiple linear regression, Spearman’s correlation coefficient and Wilcoxon signed-rank test to identify differences and key predictors. The study indicates a 22.7% decrease in children’s PA upon transitioning from kindergarten to primary school, highlighting the significant impact of school environments. Family lifestyle’s impact on school-day step count was not proven. Based on the study school environments and structured activities crucially impact children’s PA, leading to a significant decrease during the transition from kindergarten to primary school. There is an urgent need to take all possible actions, initiatives and policies to promote pupils’ school-day PA.
Treinamento moderado reduz gordura epicárdica e hipertrigliceridemia afeta plexo cardíaco em camundongos APOCIII-TGN
Authors: Teixeira Junior Nilton Rodrigues , Komagome Bruno Jun , Jimenes Diogo Rodrigues , Schultz Cristiany , Barbosa Carmem Patricia , Berti Jairo Augusto
Published: August 2024

A hipertrigliceridemia está diretamente relacionada ao aumento global de doenças cardiovasculares e metabólicas. Tal condição clínica pode ser investigada por meio de modelos animais com alteração gênica e proteica da apolipoproteína CIII (apoCIII). O plexo cardíaco e o tecido adiposo epicárdico (TAE) são importantes estruturas cardíacas com papéis vitais no processamento nervoso do coração e na disponibilização de suporte e energia para a sua contração. Este estudo analisou o plexo cardíaco e o TAE de camundongos transgênicos (CIII) e não-transgênicos (NTG), submetidos a um treinamento físico em esteira, (3 dias na semana por 40 minutos a 60% da velocidade pico) durante 8 semanas. Os animais CIII apresentaram hipertrigliceridemia e hipercolesterolemia. No entanto, a superexpressão da apoCIII não modificou a glicemia, a massa corporal e cardíaca, e a área dos adipócitos do TAE. Todavia, a área neuronal dos animais CIII foi significativamente menor (NTG Sed 193±38 µm2 vs. CIII Sed 161±11 µm2) do que a dos animais não transgênicos. Com o treinamento, a área dos adipócitos do TAE foi menor, de modo independente da expressão da apoCIII (NTG Sed 380±60 µm2; CIII Sed 358±58 µm2; NTG Ex 305±52 µm2; CIII Ex 307±57 µm2), mas não houve alteração na área neuronal. Conclui-se que os grupos treinados presentaram menor área nos neurônios do plexo cardíaco, enquanto os CIII tiveram redução deste parâmetro.
Fabrication of Wafer-Level Vacuum-Packaged 3C-SiC Resonant Microstructures Grown on <111> and <100> Silicon
Authors: Sapienza Sergio , Belsito Luca , Ferri Matteo , Elmi Ivan , Zielinski Marcin , La Via Francesco , Roncaglia Alberto
Published: August 2024

In this work, the fabrication of wafer-level vacuum packaged 3C-SiC resonators obtained from layers grown on <100> and <111> silicon is reported. The resonant microstructures are double-clamped beams encapsulated by glass-silicon anodic bonding using titanium-based vacuum gettering. Open-loop resonance frequency measurements are performed on the vacuum-packaged devices showing Q-factor values up to 292,000 for <100> and 331,000 for <111> substrates, with a maximum vacuum level around 10-2 mbar inside the encapsulations with Ti getter.
Low Resistivity Aluminum Doped Layers Formed Using High Dose High Temperature Implants and Laser Annealing
Authors: Mazzamuto Fulvio , Chehadi Zeinab , Roze Fabien , Opprecht Mathieu , Gupta Atul , Kerdilès Sébastien , Tabata Toshiyuki , Ameen Mike , Roh Dwight Dongwan , Sohl Christina , Lazar Mihai , Rubin Leonard M. , Thuries Louis
Published: August 2024

This paper demonstrates for the first time a new annealing scheme to form p-type junctions in SiC by high temperature ion implantation followed by laser annealing without the use of a protective carbon capping layer. This novel approach leverages higher substrate temperatures during implant to minimize implant-induced defects during ion implantation, which enables the use of reduced thermal budget laser annealing for dopant activation. Laser annealing enables higher surface temperatures in the implanted layer than conventional annealing using a high temperature furnace. The shorter thermal budget results in higher dopant activation while minimizing, the formation of extended defects observed during high thermal budget furnace annealing, which can lead to undesirable degradation in device performance. By using laser annealing with no carbon capping layer, the sheet resistance of the implanted layers is reduced up to 6 times with respect to the conventional process (using a furnace anneal and carbon capping layers).
High-K Gate Dielectric for High-Performance SiC Power MOSFET Technology with Low Interface Trap Density, Good Oxide Lifetime (ttddb≥ 104s), and High Thermal Stability (≥ 800 °C)
Authors: Chand Umesh , Bera Lakshmi Kanta , Singh Navab , Zhixian Chen , Kumar Shiv , Voo Qin Gui Roth , Yeo Abdul Hannan , Varghese Binni , Reddy Vudumula Pavan , Cakmak Huseyin , Ranjan Akhil , Lin Huamao , Chung Surasit
Published: August 2024

In this work, we demonstrate SiC/high-κ MOS capacitors with low leakage density of 10-8 Acm-2, good device uniformity, good thermal stability (> 800 °C), and longer oxide lifetime > 104 s simultaneously. This is enabled by using atomic layer deposition (ALD) processed- HfAlO as the gate dielectric with a thickness of 35 nm, smooth surface (RMS roughness =0.70 nm), and high-quality SiC/ HfAlO interface with interface density (Dit) of 8×1010 eV-1cm-2.
High-Volume SiC Epitaxial Layer Manufacturing-Maintaining High Materials Quality of Lab Results in Production
Authors: Thomas Bernd , Baierhofer Daniel , Staiger F. , Bierhoff Christian
Published: August 2024

Typically, research and development (R&D) results of epitaxial layer growth show superior properties of the grown layers compared to high volume results. Layer uniformities are excellent and achieved defect densities are low compared to typical results. In particular, the conversion of basal plane dislocations (BPD) from the silicon carbide (SiC) substrate is in focus to reduce bipolar degradation of p-n-junctions. It is a great challenge to maintain those excellent results in high-volume manufacturing considering all the factors that impact the properties of the epilayer. Thus, quality of the layers, high throughput and low cost have to be assessed to find a compromise between these key factors. In this paper we present results on the growth of epitaxial layers on 150 mm and 200 mm 4° off-oriented 4H-SiC substrates using warm-wall multi-wafer chemical vapor deposition (CVD) systems. Single wafer data of the key epitaxial layer parameters, thickness, doping and defect densities, are compared to batch and lot results, as well as to statistical data of several hundreds of wafers produced. Improvements in wafer-to-wafer (w-t-w) doping uniformity could be achieved for instance by implementation of an on-wafer temperature measurement. Substrate impact on defect levels is shown comparing X-ray topography (XRT) results of bare substrate wafers and defect analysis of epilayers on sister wafers from the same crystal. Statistical defect data and resulting predicted yield loss also show a dependence on substrate suppliers. For the first time we show w-t-w and run-to-run (r-t-r) results of doping and thickness measurements on 200 mm substrates. Also, defect results of epilayers on 200 mm wafers are compared to results on 150 mm.
Investigating Dislocation Arrays Induced by Seed Scratches during PVT 4H-SiC Crystal Growth Using Synchrotron X-Ray Topography
Authors: Cheng Qian Yu , Liu Yafei , Chen Ze Yu , Hu Shanshan , Raghothamachar Balaji , Dudley Michael , Pushkarev Vladimir , Moeggenborg Kevin , Chung Gil , Sanchez Edward , Soukhojak Andrey
Published: August 2024

The influence of seed preparation on crystal defect generation is studied by investigating the effect of damage from surface scratches not completely removed during polishing on the seed crystal on the nucleation and evolution of dislocation arrays. Synchrotron X-ray topography is conducted on several wafers sliced from a PVT-grown 4H-SiC boule. Topographic results in conjunction with ray tracing simulation reveal the generation of TSD/TMD and TED arrays associated with the scratches in the newly grown wafer adjacent to the seed. Configuration transformation of those arrays is observed as these opposite-signed dislocation pairs composing the arrays were affected by the overgrowth of macro-steps when propagating into the newly grown crystal.
Analysis of Forward Bias Degradation Reduction in 4H-SiC PiN Diodes on Bonded Substrates
Authors: Uchida Hidetsugu , Kobayashi Motoki , Hatta Naoki , Ishikawa Seiji , Ozono Kunihide , Masumoto Keiko , Kurihara Shunsuke , Harada Shinsuke , Kojima Kazutoshi
Published: August 2024

Analysis of forward bias degradation reduction of 4H-Silicon Carbide (4H-SiC) PiN diodes on bonded substrates was performed. In the analysis, cathodoluminescence (CL), photoluminescence imaging (PL imaging), and transmission electron microscope (TEM) were used. Under high forward bias stress, the Shockley-type stacking fault (SSF) does not expand into the transferred layer of the bonded substrate, while in the monocrystalline substrate, the SSF expands below the epilayer/substrate interface. The basal plane dislocation (BPD) within the transferred layer does not expand to the SSF. The transferred layer has the effect of suppressing the expansion of SSFs. This effect can be caused by hydrogen implantation for wafer splitting to produce bonded SiC substrates.
Experimental Observation of Raman Assisted and Kerr Optical Frequency Comb in a 4H-Silicon-Carbide on Insulator Microresonator
Authors: Afridi Adnan Ali , Lu Yao Qin , Shi Xia Dong , Wang Rui Xuan , Li Jing Wei , Li Qing , Ou Hai Yan
Published: August 2024

Kerr nonlinear microcavities have garnered significant interest owing to their rich dynamics of nonlinear optical phenomena and compatibility with on-chip photonic integration. Recently, silicon carbide has emerged as a compelling platform due to its unique optical properties. In this study, we demonstrate Raman-assisted and Kerr optical frequency generation in a 4H-silicon carbide-on-insulator microresonator. By pumping the transverse electric (TE00) mode within the device, we observe a stimulated Raman scattering (SRS) Stokes with the Raman shift at approximately 775 cm-1, achieved with an on-chip power of 350 mW. Furthermore, by red-tuning the TE00 pump wavelength, we have achieved the coexistence of Raman and Kerr frequency combs. Using another device on the same chip with light variation of the taper we can observe the Raman and Kerr frequency combs within a spectral bandwidth ranging from ∼ 1440 to 1960 nm. The inclusion of the Raman-assisted comb extends the comb’s coverage into longer wavelength regimes, making it highly desirable for spectroscopy applications.
Monitoring of Graphene Properties in the Process of Viral Biosensor Manufacturing
Authors: Lebedev Alexander A. , Shmidt Natalia M. , Shabunina Evgeniya I. , Nashchekin Alexey V. , Gushchina Ekaterina V. , Petrov Vasiliy N. , Eliseev Ilya A. , Lebedev Sergey P. , Priobrazhenskii Sergei Iu. , Roenkov Alexander D. , Tanklevskaya Elena M. , Puzyk Mikhail V. , Usikov Alexander S. , Klotchenko Sergey A. , Vasin Andrey V. , Plehanov Anton Yu. , Golyashow Vladimir A. , Tereshchenko Oleg Evgenievich
Published: August 2024

The properties of graphene chips with low reproducibility (LR) after photolithography (PLG) and graphene functionalization have been studied. It is shown that the introduction of additional cleaning after PLG can significantly increase the reproducibility of the parameters of processed graphene in biosensors. The use of dilute PBS solutions for virus detection makes it possible to increase the relative concentration sensitivity of biosensors by several times.
Effect of Substrate Heating on Low Contact-Resistance Formation by Excimer Laser Doping for 4H-SiC
Authors: Kakimoto Yoshiaki , Yasunami Takuma , Katayama Keita , Nakamura Daisuke , Goto Tetsuya , Ikenoue Hiroshi
Published: August 2024

N atoms were doped into SiNx/4H-SiC substrates by KrF laser irradiation while the substrates were heated. The diffusion depth of nitrogen increased above the solubility limit when the sample heated to 600°C was irradiated by the laser compared to the sample at room temperature. In addition, a clear 4H-SiC pattern was observed in the cross-sectional TEM diffraction image, thereby suggesting that sufficient crystal recovery was achieved even under melt-solidification conditions owing to the effect of substrate heating.
Evaluation of Novel Concepts for Takeover Control using Electronically Coupled Sidesticks
Authors:   German Aerospace Centre - DLR, Sampaio Rodolfo , Jones Michael , Walko Christian
Published: August 2024

Helicopter accident investigation reports indicate that takeover control maneuvers in low level flight may lead to loss-of-control. In this paper, novel methods for control transfer are implemented to address this safety issue. Through the use of active inceptor systems, the traditional mechanical linkage between pilot and copilot inceptors can be emulated using priority functions, which act to actively decouple inceptors in one control station. Takeover control maneuvers are tested in a dual pilot helicopter simulation environment to evaluate two inceptor decoupling methods, namely a priority pushbutton (manual) and a priority force threshold (automatic). Results indicate that the takeover maneuvers were successfully performed in low level flight without over control when using both priority functions. The priority functions led to a workload reduction when compared to a benchmark configuration without inceptor decoupling. Positive ratings in usefulness and satisfaction scales indicate pilot acceptance of the priority functions tested.
Evaluating Disruptive Tuned Mass Vibration Attenuators in Rotary Wing Applications
Authors:   The University of Alabama in Huntsville, Duling Christopher ,   Linc Research Inc., Lindner Jeffrey
Published: August 2024

This paper examines the performance of passive structural vibration attenuating devices in rotary wing applications and introduces a new attenuating device to rotary wing applications, the NASA-developed Disruptive Tuned Mass (DTM) device. The testbed uses an OH-58D tailboom rigidly mounted to the floor as a cantilever beam with a first lateral mode resonant frequency of approximately 6.25 Hz as a representative rotary wing structure. The study characterizes the modal response of the tailboom without an attenuating device installed, with additional mass installed, a mass-spring attenuating device, a fixed orifice Tuned Mass Damper (TMD), and a device based on NASA DTM technology. TMD and DTM devices were tested with 6 lbs (2.72 kg) and 19 lbs (8.61 kg) mitigation masses. The DTM devices achieved greater modal attenuation than the TMD devices, 88% and 96% respectively, for devices with 6 lbs (2.72 kg) and 19 lbs (8.61 kg) active masses.
Rotary Inspection Tracking System
Authors:   GS Engineering Inc., Cooke M. ,   ThermoAnalytics Inc., Packard Corey , Kramer Mandy , Webb Traci , Edel Zachary
Published: August 2024

A technology is in development to provide automated non-contact identification of the presence or absence of cracking, composite delamination, and fatigue damage on H-60 Black Hawk main rotor assembly components. The subject technology design employs passive thermography to capture images of the main rotor blades, rotor hub, and swashplate assembly while the helicopter is in flight, and executes a custom software program to enhance infrared images and detect flaws post-flight. The technology aims to provide selective periodic maintenance and inspection without removal of components from the aircraft or artificial thermal stimulation. In addition to identifying damaged components, the RITS (Rotary Inspection Tracking System) evaluates when maintenance interval or end of life components can be approved for extended use due to absence of damage. Analytical thermal simulations of the blades were developed and a series of flight tests were performed to validate the models and identify thermal heating profiles during flight. A test fixture was utilized to evaluate the detection algorithm functionality by imaging realistic fabricated flaws. Compiled results from the test fixture and on-aircraft testing demonstrate the feasibility of detecting flaws using passive thermography during helicopter flight.
Transfer-of-Training: From Fixed- and Motion-base Simulators to a Light-Weight Helicopter
Authors:   Max Planck Institute for Biological Cybernetics, Fabbroni Davide , Bufalo Francesco , D'Intino Giulia , Geluardi Stefano , Gerboni Carlo , Olivari Mario , Bülthoff Heinrich
Published: August 2024

This paper aims at understanding whether helicopter flight simulators need motion bases for pilot training. While increased realism improves the Transfer-of-Training effectiveness of the simulator, it also increases costs. In this study a two-steps experiment was performed to provide evidence of motion simulators cost-effectiveness on initial pilot training. First, inexperienced student pilots participants were trained to perform a hover maneuver in a highly realistic motion simulator. The participants were divided into two groups: the first group was trained in a fixed-based condition and one in a motion-base condition. Second, a sample of participants was selected and transferred to an actual helicopter to evaluate the Transfer-of-Training and the motion feedback contribution on the participants of the motion-base condition. A Robinson R44 helicopter was sensorized to use objective measurements in support of the instructor pilots subjective evaluations. Overall, the results demonstrated the effectiveness of the training performed in the simulator, as most participants were able to stabilize and hover the helicopter both in the simulated environment and in the actual scenario. However, no difference between the two training groups was detected, suggesting that the fixed-base condition was more cost-effective.
Evaluation of Pilot Workload for Helicopter Optimal Autorotation Landing Procedure in One Engine Failure
Authors:   Nanjing University of Aeronautics and Astronautics, Yan Xufei , Chen Renliang
Published: August 2024

This paper intends to evaluate the pilot workload of helicopter optimal autorotation landing procedure in the event of one engine failure to provide a reference for the pilot conducting the actual autorotation landing maneuver. The UH-60A helicopter is taken as the sample for demonstration. The autorotation landing procedure is formulated into a nonlinear optimal control problem (NOCP) based on an augmented six-degree-of-freedom rigid-body flight dynamics model, solved by collocation and numerical optimization method. The optimal landing trajectory and controls are compared with those from the flight test data. Metrics called aggressiveness and pilot cutoff frequency are applied to quantify and evaluate the pilot workloads respectively in time domain and frequency domain, based on the pilot control inputs of the optimal solution and the flight test data. The results show that optimal landing procedure is close to the flight test data, and the analysis of the metrics indicates that the pilot workload evaluated can be considered consistent with that from the flight test.
Design of Dynamic Inversion and Explicit Model Following Control Laws for Quadrotor Inner and Outer Loops
Authors:   The Pennsylvania State University, Saetti Umberto ,   U.S. Army AMRDEC, Berger Tom , Horn Joseph , Lakhmani Sagar , Lagoa Constantino
Published: August 2024

A quadrotor was assembled with commercial off the-shelf (COTS) components readily available on the market as a platform for future research at Penn State. As a first step in this research, a model of the quadrotor is identified from flight data. Given the largely decoupled dynamics at low speed, frequency sweeps in different channels are performed separately on the roll, pitch, yaw and heave axes. A frequency-domain approach is used to perform system identification. First, frequency responses of the aircraft output are extracted from frequency-sweep flight data. Next, state-space models are fit to the frequency response data. Overall the identified model matched flight data well in both the frequency and time domain. Dynamic Inversion (DI) and Explicit Model Following (EMF) with LQR disturbance rejection control laws are developed for both an inner attitude loop and outer velocity loop. The control laws were developed to meet similar requirements, and have similar performance and robustness.
Design Space Exploration of Pericyclic Transmission with Counterbalance and Bearing Load Analysis
Authors:   NASA Glenn Research Center, Cameron Zachary ,   Pennsylvania State University, Smith Edward ,   University of Tennessee, DeSmidt Hans , Bill Robert
Published: August 2024

The pericyclic transmission provides the opportunity to vastly impact transmission design in rotorcraft due to its ability to provide exceedingly high reduction ratios in a single stage that would normally require multiple gear stages. This could lead to lighter transmissions with fewer components, increased reliability, efficiency, speed and decreased cost to maintain. While many previous studies have focused upon the gearing within the pericyclic transmission, this work focused on what influences pericyclic geometry, and how changes in geometry impact bearing loads. Specifically, the loading of bearings that must deliver power from the input shaft to the nutating and rotating gears of the system were of primary concern. A comprehensive look at dynamic loads generated by nutating bodies was performed. Methods to address these dynamic loads via application of counterbalances, and deviation from conventional pericyclic transmission designs were utilized to negate the dynamic moment of concern. Counterbalances negating the dynamic moment were shown to weigh between 30-50% of the pericyclic motion converter gears in a 40:1 reduction ratio pericyclic design at 12,000 rpm input speed and reduced applied moments by three orders of magnitude. Finally, a static solver was used to determine the bearing loads with updated component geometries and mass moment of inertias that included the required counterbalances.
Evaluation of a Variable Thickness Hybrid Composite Bull Gear
Authors:   US Army Research Laboratory, LaBerge Kelsen ,   Universities Space Research Association, Johnston Joel ,   NASA Glenn Research Center, Handschuh Robert , Roberts Gary
Published: August 2024

For several years, NASA Glenn Research Center and the U.S. Army Research Laboratory have been investigating hybrid (composite/steel) gear technology for use in vertical lift drive systems. The hybrid gear concept replaces the structural portion of a gear between the shaft and the gear rim with a lightweight carbon fiber composite, in an effort to reduce the overall weight of a gear and increase the drive system power density. Past research includes both small-scale and large-scale hybrid gear concepts, all of which have a constant composite thickness throughout. The design described in this paper is of a variable thickness, such that the composite is thickest at the inner diameter and this thickness is gradually reduced toward the outer diameter. The resulting "stair stepped" design stems from dropping plies of the braided carbon fiber prepreg composite fabric gradually with increased radius. Additionally, the interlock pattern at the inner metallic adapter was adjusted slightly from previous designs to obtain a better stress distribution on the inner metallic adapter. The manufactured variable thickness web was tested both in static torsion tests and operationally in a relevant gearbox environment. The results of these experiments will be presented and compared to a baseline steel configuration.
Temperature Rise and Tooth Surface Evolution of Gearbox under Loss of Lubrication: Experimental and Numerical Investigation
Authors:   United Technologies Research Center, Zhang Huan ,   US Army - Aviation Development Directorate/Aviation Applied Technology Directorate, Maglieri John , Sun Fanping , Wu Hailing , Chaudhry Zaffir
Published: August 2024

Loss of the primary lubrication in a helicopter gearbox can result in a very rapid or immediate failure of the transmission system due to drastic reduction in heat removal and the degrading tribological performance of the highly loaded gear contacts. Current methods for predicting the gearbox life and performance under loss-of-lubrication condition are largely experimental and experience-based and thus provide limited insights into the underlying physics of the evolving tribology of gears and bearings. One of the major technical barriers that currently constrain the physics-based predictive capability is the limited understanding and quantitative modeling of the thermomechanical response of tooth surface after the loss of lubrication. The experimental portion of the effort described in this paper is a systematic study of the temperature rise and tooth surface evolution for a generic gearbox under loss-of-lubrication conditions. The overall thermal conditions of the gearbox are monitored through an infrared thermal imaging camera and the transient temperatures at multiple locations of gear and pinions are continuously measured with thermocouples. Tooth samples from different stages towards the final thermal runaway were examined to reveal the underlying physics of the surface evolution and failure after the loss of lubrication. In the modeling effort, FE modeling was combined with the transient thermal mixed-EHL model of gear meshing to simulate the gear thermal response and a sensitivity study was conducted with the validated thermal model to evaluate the potential underlying physics of the thermal runaway. The combined heat generation from frictional sliding and plastic deformation was also determined through the FE simulation of mesoscale sliding contact of tooth surface. The experimental and numerical results suggest that the potential mechanism of the final catastrophic failure is the adiabatic shear instability associated with severe plastic deformation and phase transformation.