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The Impact of Sleep Patterns on Academic Performance and Social Integration among Medical Students
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作者 Livia-Ștefana Găgilă Tudor Cojocaru +5 位作者 Giulia-Mihaela Pînzariu Daria Georgiana Sauciuc Diana Elena Lupașcu Livia Amira Sauciuc Ioana Ilinca Ursachianu Elena Cojocaru 《Journal of Biosciences and Medicines》 2024年第8期189-198,共10页
Introduction: The impact of sleep on student life is crucial, particularly for those in demanding fields such as medicine. This study examines the relationships between sleep patterns, academic performance, and social... Introduction: The impact of sleep on student life is crucial, particularly for those in demanding fields such as medicine. This study examines the relationships between sleep patterns, academic performance, and social integration among medical students, who often face irregular sleep cycles and sleep deprivation due to rigorous academic demands. Aim: This study aims to assess how sleep issues affect academic achievement and social relationships among medical students. Method: Data were collected from 215 medical students through surveys and academic records. Quantitative data provided insights into sleep quality and academic performance, while qualitative interviews explored the effects of sleep on social interactions. Results: The findings revealed a significant correlation between sleep quality and academic performance, with students reporting better sleep hygiene achieving higher grades. Qualitative data indicated that poor sleep negatively impacts social interactions, leading to feelings of isolation and reduced social participation. Conclusions: The study highlights the importance of promoting good sleep practices in medical schools to enhance academic success and social well-being. Interventions aimed at improving sleep quality may help reduce burnout and improve overall well-being among medical students. Future research should focus on longitudinal studies to better understand the long-term effects of sleep on academic and social outcomes in this population. 展开更多
关键词 student MEDICINE Sleep Quality Academic performance
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Video Games and School Performances of Dakar High School Students
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作者 Souleymane Diallo Papa Mamadou Gaye 《Open Journal of Applied Sciences》 2024年第7期1851-1862,共12页
The triptych (Smartphones, Video games, adolescents) has imposed itself on the collective consciousness in the form of questioning to the point of becoming a social phenomenon. It thus raises concerns about the uses t... The triptych (Smartphones, Video games, adolescents) has imposed itself on the collective consciousness in the form of questioning to the point of becoming a social phenomenon. It thus raises concerns about the uses that adolescents make of it and the effects on their academic performance, which we proposed to study among middle school students from the Dakar academy inspection. Where appropriate, we used mixed methods with the collection techniques of questionnaire survey, semi-structured interviews respectively with middle school students, adults (parents, supervisors, teachers, etc.), participant observation and literature review. Concretely, before accessibility to video games, the middle school students were more idle and well-behaved, watched a lot of TV, played with their brothers and sisters or did household chores. The majority of young people had good, very good or excellent conduct and their averages were fair, fairly good or good. With access to a diverse digital environment, middle school students have passionately turned to video games. As a result, their learning time, concentration and submission to parental injunctions have declined significantly. This situation negatively affected their academic performance and encouraged bad behavior. 展开更多
关键词 Digital Revolution Video Games Middle School student EDUCATION Academic performance
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A Stacking Machine Learning Model for Student Performance Prediction Based on Class Activities in E-Learning
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作者 Mohammad Javad Shayegan Rosa Akhtari 《Computer Systems Science & Engineering》 2024年第5期1251-1272,共22页
After the spread of COVID-19,e-learning systems have become crucial tools in educational systems worldwide,spanning all levels of education.This widespread use of e-learning platforms has resulted in the accumulation ... After the spread of COVID-19,e-learning systems have become crucial tools in educational systems worldwide,spanning all levels of education.This widespread use of e-learning platforms has resulted in the accumulation of vast amounts of valuable data,making it an attractive resource for predicting student performance.In this study,we aimed to predict student performance based on the analysis of data collected from the OULAD and Deeds datasets.The stacking method was employed for modeling in this research.The proposed model utilized weak learners,including nearest neighbor,decision tree,random forest,enhanced gradient,simple Bayes,and logistic regression algorithms.After a trial-and-error process,the logistic regression algorithm was selected as the final learner for the proposed model.The results of experiments with the above algorithms are reported separately for the pass and fail classes.The findings indicate that the accuracy of the proposed model on the OULAD dataset reached 98%.Overall,the proposed method improved accuracy by 4%on the OULAD dataset. 展开更多
关键词 STACKING E-LEARNING student performance prediction machine learning CLASSIFICATION
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A Feature Learning-Based Model for Analyzing Students’ Performance in Supportive Learning
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作者 P.Prabhu P.Valarmathie K.Dinakaran 《Intelligent Automation & Soft Computing》 SCIE 2023年第6期2989-3005,共17页
Supportive learning plays a substantial role in providing a quality edu-cation system.The evaluation of students’performance impacts their deeper insight into the subject knowledge.Specifically,it is essential to mai... Supportive learning plays a substantial role in providing a quality edu-cation system.The evaluation of students’performance impacts their deeper insight into the subject knowledge.Specifically,it is essential to maintain the baseline foundation for building a broader understanding of their careers.This research concentrates on establishing the students’knowledge relationship even in reduced samples.Here,Synthetic Minority Oversampling TEchnique(SMOTE)technique is used for pre-processing the missing value in the provided input dataset to enhance the prediction accuracy.When the initial processing is not done substantially,it leads to misleading prediction accuracy.This research concentrates on modelling an efficient classifier model to predict students’perfor-mance.Generally,the online available student dataset comprises a lesser amount of sample,and k-fold cross-validation is performed to balance the dataset.Then,the relationship among the students’performance(features)is measured using the auto-encoder.The stacked Long Short Term Memory(s-LSTM)is used to learn the previous feedback connection.The stacked model handles the provided data and the data sequence for understanding the long-term dependencies.The simula-tion is done in the MATLAB 2020a environment,and the proposed model shows a better trade-off than the existing approaches.Some evaluation metrics like pre-diction accuracy,sensitivity,specificity,AUROC,F1-score and recall are evalu-ated using the proposed model.The performance of the s?LSTM model is compared with existing approaches.The proposed model gives 89% accuracy,83% precision,86%recall,and 87%F-score.The proposed model outperforms the existing systems in terms of the earlier metrics. 展开更多
关键词 student performance quality education supportive learning feature relationship auto-encoder stacked LSTM
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Evolutionary Algorithm Based Feature Subset Selection for Students Academic Performance Analysis
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作者 Ierin Babu R.MathuSoothana S.Kumar 《Intelligent Automation & Soft Computing》 SCIE 2023年第6期3621-3636,共16页
Educational Data Mining(EDM)is an emergent discipline that concen-trates on the design of self-learning and adaptive approaches.Higher education institutions have started to utilize analytical tools to improve student... Educational Data Mining(EDM)is an emergent discipline that concen-trates on the design of self-learning and adaptive approaches.Higher education institutions have started to utilize analytical tools to improve students’grades and retention.Prediction of students’performance is a difficult process owing to the massive quantity of educational data.Therefore,Artificial Intelligence(AI)techniques can be used for educational data mining in a big data environ-ment.At the same time,in EDM,the feature selection process becomes necessary in creation of feature subsets.Since the feature selection performance affects the predictive performance of any model,it is important to elaborately investigate the outcome of students’performance model related to the feature selection techni-ques.With this motivation,this paper presents a new Metaheuristic Optimiza-tion-based Feature Subset Selection with an Optimal Deep Learning model(MOFSS-ODL)for predicting students’performance.In addition,the proposed model uses an isolation forest-based outlier detection approach to eliminate the existence of outliers.Besides,the Chaotic Monarch Butterfly Optimization Algo-rithm(CBOA)is used for the selection of highly related features with low com-plexity and high performance.Then,a sailfish optimizer with stacked sparse autoencoder(SFO-SSAE)approach is utilized for the classification of educational data.The MOFSS-ODL model is tested against a benchmark student’s perfor-mance data set from the UCI repository.A wide-ranging simulation analysis por-trayed the improved predictive performance of the MOFSS-ODL technique over recent approaches in terms of different measures.Compared to other methods,experimental results prove that the proposed(MOFSS-ODL)classification model does a great job of predicting students’academic progress,with an accuracy of 96.49%. 展开更多
关键词 studentsperformance analysis educational data mining feature selection deep learning metaheuristics outlier detection
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Effects of Fatigue Characteristics on Static and Dynamic Performance of Eucommia Rubber Isolators
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作者 Yongsheng Peng Junfeng Yang +2 位作者 Guopei Pan Jianan Zhang Zhuo Wang 《Journal of Applied Mathematics and Physics》 2023年第7期2165-2177,共13页
This study aimed to investigate the effect of fatigue characteristics on the static and dynamic performance of Eucommia ulmoides gum isolators, and to explore the performance changes of Eucommia ulmoides gum isolators... This study aimed to investigate the effect of fatigue characteristics on the static and dynamic performance of Eucommia ulmoides gum isolators, and to explore the performance changes of Eucommia ulmoides gum isolators with different formulations. For this purpose, we used five formulations of Eucommia ulmoides gum isolators and set different fatigue test methods to study the static and dynamic performance changes of Eucommia ulmoides gum isolators with different formulations by changing the amplitude. The experimental results showed that the addition of Eucommia ulmoides gum had an impact on the performance of the isolator, and the number of fatigue cycles would lead to the hardening of the Eucommia ulmoides gum isolator and changes in its static and dynamic performance. In the range of two million vibrations, the performance change of the isolator was significant in the early stage and then tended to be flat, indicating that the impact of fatigue on the performance of the isolator would not continue to persist. It is worth noting that the study found that the addition of 30% Eucommia ulmoides gum had the least impact on the performance of the isolator under fatigue. Therefore, for long-term use of Eucommia ulmoides gum isolators, attention should be paid to their fatigue characteristics to ensure their stability and reliability. Additionally, this study provides a reference for the design and application of Eucommia ulmoides gum isolators. In summary, this study provides important reference value for a deeper understanding of the fatigue characteristics of Eucommia ulmoides gum isolators and for ensuring their stable and reliable performance. . 展开更多
关键词 Fatigue characteristics Eucommia Rubber Vibration Isolators Static performance Dynamic performance
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The Effect of “Think-Talk-Write” Strategy on EFL Tenth-Grade Students’ Writing Performance
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作者 Mohammad Mahmoud Azzam Abdallah Baniabdelrahman 《Journal of International Education and Practice》 2023年第1期1-9,共9页
This study investigated the effect of“Think-Talk-Write strategy”on English as a Foreign Language(EFL)tenth-grade students'writing performance.A quasi-experimental design with two groups was employed.The research... This study investigated the effect of“Think-Talk-Write strategy”on English as a Foreign Language(EFL)tenth-grade students'writing performance.A quasi-experimental design with two groups was employed.The researcher randomly assigned two whole sections of grade 10 from Al-Kharaj Secondary School for Boys.The first section was chosen as the experimental group with(20)students,and the second as the control group with(20).To achieve the purpose of the study,a pre/post writing performance test was designed.In addition,Think-Talk-Write(TTW)strategy was used to teach the experimental group,whereas a control group was taught by the conventional teaching strategies,as suggested in the teacher's book.Results revealed that TTW strategy enhanced students’writing performance.In light of the research results,the researcher recommends to use TTW strategy on other genres of writing. 展开更多
关键词 EFL Jordanian students Reading performance TTW Strategy
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Changes in visual performance after implantation of different intraocular lenses
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作者 Bo-Wen Li Hao Huang +10 位作者 Man-Sha Huang Shuang-Lin Guo Lu Gao Yu-Ying Zeng Lu Cheng Si-Yang Yao Jian-Qiang Lin Lin Liu Ye Yang Xiao-Ming Lu Hao Cheng 《International Journal of Ophthalmology(English edition)》 SCIE CAS 2024年第7期1273-1282,共10页
AIM:To evaluate the trending visual performance of different intraocular lenses(IOLs)over time after implantation.METHODS:Ninety-one patients received cataract surgery with implantations of monofocal(Mon)IOLs,segmenta... AIM:To evaluate the trending visual performance of different intraocular lenses(IOLs)over time after implantation.METHODS:Ninety-one patients received cataract surgery with implantations of monofocal(Mon)IOLs,segmental refractive(SegRef)IOLs,diffractive(Dif)IOLs,and extendeddepth-of-focus(EDoF)IOLs were included.The aberrations and optical quality collected with iTrace and OQAS within postoperative 6mo were followed and compared.RESULTS:Most of the visual parameters improved over the postoperative 6mo.The postoperative visual acuity(POVA)of the Mon IOL,SegRef IOL,and EDoF IOL groups achieved relative stability in earlier states compared with the Dif IOL group.Nevertheless,the overall visual performance of the 3 IOLs continued to upturn in small extents within the postoperative 6mo.The optical quality initially improved in the EDoF IOL group,then in the Mon IOL,SegRef IOL,and Dif IOL groups.POVA and objective visual performance of the Mon IOL and EDoF IOL groups,as well as POVA and visual quality of the Dif IOL group,improved in the postoperative 1mo and stabilized.Within the postoperative 6mo,gradual improvements were observed in the visual acuity and objective visual performance of the SegRef IOL group,as well as in the postoperative optical quality of the Dif IOL group.CONCLUSION:The visual performance is different among eyes implanted with different IOLs.The findings of the current study provide a potential reference for ophthalmologists to choose suitable IOLs for cataract patients in a personalized solution. 展开更多
关键词 intraocular lenses visual performance changing characteristics high-order wavefront aberration
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Research on Leading Edge Erosion and Aerodynamic Characteristics of Wind Turbine Blade Airfoil
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作者 Xin Guan Yuqi Xie +2 位作者 Shuaijie Wang Mingyang Li Shiwei Wu 《Fluid Dynamics & Materials Processing》 EI 2024年第9期2045-2058,共14页
The effects of the erosion present on the leading edge of a wind turbine airfoil(DU 96-W-180)on its aerodynamic performances have been investigated numerically in the framework of a SST k–ωturbulence model based on ... The effects of the erosion present on the leading edge of a wind turbine airfoil(DU 96-W-180)on its aerodynamic performances have been investigated numerically in the framework of a SST k–ωturbulence model based on the Reynolds Averaged Navier-Stokes equations(RANS).The results indicate that when sand-induced holes and small pits are involved as leading edge wear features,they have a minimal influence on the lift and drag coefficients of the airfoil.However,if delamination occurs in the same airfoil region,it significantly impacts the lift and resistance characteristics of the airfoil.Specifically,as the angle of attack grows,there is a significant decrease in the lift coefficient accompanied by a sharp increase in the drag coefficient.As wear intensifies,these effects gradually increase.Moreover,the leading edge wear can exacerbate flow separation near the trailing edge suction surface of the airfoil and cause forward displacement of the separation point. 展开更多
关键词 Wind energy wind turbine EROSION AIRFOIL leading edge erosion characteristics aerodynamic performance numerical simulation
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Evaluation of Chinese Learning Efficiency of International Students in China:Comparing by Dimension
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作者 LI Jin-feng ZHOU Yu-liang 《Journal of Literature and Art Studies》 2024年第8期722-725,共4页
This paper introduces the Value Engineering method to calculate the value coefficient of Chinese learning efficiency for 377 international students by dimension.Results suggest that attention should be paid to male,Eu... This paper introduces the Value Engineering method to calculate the value coefficient of Chinese learning efficiency for 377 international students by dimension.Results suggest that attention should be paid to male,European and American,rural,introverted,and“work or education needs”international students;Give full play to the driving role of the reference-type,explore the space for improving the learning efficiency of the improvement-type and attention-type,and pay attention to the problems of problem-type international students. 展开更多
关键词 international students in China evaluation of Chinese learning efficiency value engineering learning engagement learning performance
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Evaluation of Chinese Learning Efficiency of International Students in China
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作者 LI Jin-feng ZHOU Yu-liang 《Journal of Literature and Art Studies》 2024年第7期616-623,共8页
This paper investigates the related factors of Chinese learning engagement and performance of 377 students from three universities in Guangzhou of China,employs the value engineering method,and calculates the value co... This paper investigates the related factors of Chinese learning engagement and performance of 377 students from three universities in Guangzhou of China,employs the value engineering method,and calculates the value coefficient of learning efficiency.From the value coefficient of Chinese language learning,it proves that over 60%of international students studying in China have a higher efficiency in learning Chinese. 展开更多
关键词 international students in China evaluation of Chinese learning efficiency value engineering learning engagement learning performance
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Study on Characteristics of a High-Precision Cold Gas Micro Thruster
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作者 Zhaoli Wang Changbin Guan +2 位作者 Xudong Wang Weijie Zheng Longfei Su 《Engineering(科研)》 2024年第1期38-45,共8页
In order to improve the reliability of the spacecraft micro cold gas propulsion system and realize the precise control of the spacecraft attitude and orbit, a micro-thrust, high-precision cold gas thruster is carried ... In order to improve the reliability of the spacecraft micro cold gas propulsion system and realize the precise control of the spacecraft attitude and orbit, a micro-thrust, high-precision cold gas thruster is carried out, at the same time due to the design requirements of the spacecraft, this micro-thrust should be continuous working more than 60 minutes, the traditional solenoid valve used for the thrusts can’t complete the mission, so a long-life micro latching valve is developed as the control valve for this micro thruster, because the micro latching valve can keep its position when it cuts off the outage. Firstly, the authors introduced the design scheme and idea of the thruster. Secondly, the performance of the latching valve and the flow characteristics of the nozzle were simulated. Finally, from the experimental results and compared with the numerical study, it shows that the long-life micro cold gas thruster developed in this paper meets the mission requirements. 展开更多
关键词 High-Precision Micro Thruster performance Flow characteristic EXPERIMENT
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Preparedness training programs improved the emergency response and crucial outcomes among nursing students:a scoping review
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作者 Budi Mulyana Rian Adi Pamungkas +3 位作者 Widia Sari Anita Sukarno Ernalinda Rosya Wiwik Wariani 《Frontiers of Nursing》 2024年第2期159-167,共9页
Objective:The study aims to review and discuss the outcomes of emergency preparedness training programs among nursing students.Methods:A scoping review was conducted based on the guidelines of Arskey and O’Malley.Dat... Objective:The study aims to review and discuss the outcomes of emergency preparedness training programs among nursing students.Methods:A scoping review was conducted based on the guidelines of Arskey and O’Malley.Databases through PubMed,Science Direct,and Google Scholar were used to obtain the relevant articles within the scoping review.Results:The researchers found 1175 articles.After manual review,28 articles were identified and assessed.The review reported that the emergency preparedness training program significantly affects preparedness,knowledge,performance,self-efficacy,learning motivation,self-confidence,satisfaction,critical decision-making,and problem-solving.Conclusions:Emergency training effectively increases knowledge,skills,confidence,satisfaction,and team performance. 展开更多
关键词 emergency preparedness first aid nursing students training program emergency response disaster management team performance
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On Students' Self-Evaluation and Class Performance——An Empirical Study in College English Class
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作者 朱周贤 《海外英语》 2014年第9X期291-292,共2页
This paper aims to demonstrate whether students'self-evaluations influence their class performance.A questionnaire is designed and data is collected from 30 sophomore students in English class.The data analysis sh... This paper aims to demonstrate whether students'self-evaluations influence their class performance.A questionnaire is designed and data is collected from 30 sophomore students in English class.The data analysis shows that students who have positive self-evaluation perform better and get higher class performance scores than students who have negative self-evaluation. 展开更多
关键词 students SELF-EVALUATION CLASS performance CLASS
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Impact of Remote Learning on Student Performance and Grade: A Virtual World of Education in the COVID-19 Era
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作者 Rafia Islam Olatunde Abiona 《International Journal of Communications, Network and System Sciences》 2023年第6期115-129,共15页
The COVID-19 pandemic has had a profound influence on education around the world, with schools and institutions shifting to remote learning to safeguard the safety of students and faculty. Concerns have been expressed... The COVID-19 pandemic has had a profound influence on education around the world, with schools and institutions shifting to remote learning to safeguard the safety of students and faculty. Concerns have been expressed about the impact of virtual learning on student performance and grades. The purpose of this study is to investigate the impact of remote learning on student performance and grades, as well as to investigate the obstacles and benefits of this new educational paradigm. The study will examine current literature on the subject, analyze data from surveys and interviews with students and educators, and investigate potential solutions to improve student performance and participation in virtual classrooms. The study’s findings will provide insights into the effectiveness of remote learning and inform ideas to improve student learning and achievement in an educational virtual world. The purpose of this article is to investigate the influence of remote learning on both students and educational institutions. The project will examine existing literature on the subject and collect data from students, instructors, and administrators through questionnaires and interviews. The paper will look at the challenges and opportunities that remote learning presents, such as the effect on student involvement, motivation, and academic achievement, as well as changes in teaching styles and technology. The outcomes of this study will provide insights into the effectiveness of remote learning and will affect future decisions about the usage of virtual learning environments in education. The research will also investigate potential solutions to improve the quality of remote education and handle any issues that occur. 展开更多
关键词 Remote Learning student performance Virtual World Covid-19 GRADE student Learning
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Effects of melatonin implantation on cashmere yield,fibre characteristics,duration of cashmere growth as well as growth and reproductive performance of Inner Mongolian cashmere goats 被引量:18
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作者 Chunhui Duan Jianhai Xu +2 位作者 Changmian Sun Zhihai Jia Wei Zhang 《Journal of Animal Science and Biotechnology》 SCIE CAS CSCD 2015年第4期463-468,共6页
Background: Exogenous melatonin could induce cashmere growth. However, induced growth of cashmere fleece by melatonin implants cannot be combined with the typical growth, resulting in earlier shedding followed by ano... Background: Exogenous melatonin could induce cashmere growth. However, induced growth of cashmere fleece by melatonin implants cannot be combined with the typical growth, resulting in earlier shedding followed by another cycle of cashmere growth. To address this issue, we examine the effects on the cashmere yield, fibre characteristics, and the growth and reproductive performance of cashmere goats of planned administration of melatonin. Methods: Eighteen half-sib, female goats were assigned to two treatments (n = 9) including a control and a treatment where melatonin (2 mg/kg BW) was implanted at the end of April and end of June. Cashmere growth and shedding were observed for approximately ] year following implantation. Fibre samples were collected monthly to determine cumulative cashmere length. Initiation and cessation dates for cashmere growth as well as the rate of cashmere growth were calculated. Cashmere yield, weight gain of dam, kidding date, litter size, and birth weight were also recorded. Results: Melatonin implantation increased cashmere yield by 34.5 % (control 553.7 g vs. melatonin 745.0 g; P〈 0.01), cashmere length by 21.3 % (control 95.2 mm vs. melatonin 115.4 mm; P 〈 0.01), and decreased fibre diameter by 4.4 % (control 14.6 pm vs. melatonin 14.0 IJm; P 〈 0.03). In melatonin-treated goats, the average initiation date was earlier than in control goats (May 18, 2013 vs. July 2, 20]3; P〈 0.01) but there was a similar cessation date (March 22, 2014 vs. March 27, 2014). Consequently, the duration of cashmere growth was longer in melatonin-treated goats than in control goats (307 vs.270 days; P 〈 0.01). The final BW, average daily gain, kidding date, litter size, and birth weight were not influenced by melatonin implantation. Conclusions: These data indicate that melatonin implantation (2 mg/kg BW) on two occasions (late April and June) increased cashmere yield by combining the induced growth of cashmere fleece with the typical growth and decreased the fibre diameter without changing dam growth rate or reproductive performance. 展开更多
关键词 Cashmere goat Cashmere yield Fibre characteristics Growth performance Melatonin Reproductive performance
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An Overview of Performance Characteristics, Experiencesand Trends of Aerospace Engine Bearings Technologies 被引量:27
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作者 Ebert Franz-Josef 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2007年第4期378-384,共7页
In this paper, the operating conditions, technical requirements, performance characteristics, design ideas, application experiences and development trends of aerospace engine bearings, including material technology, i... In this paper, the operating conditions, technical requirements, performance characteristics, design ideas, application experiences and development trends of aerospace engine bearings, including material technology, integration design and reliability, are reviewed. The development history of aerospace engine bearing is recalled briefly at first. Then today's material technologies and the high bearing performances of the bearings obtained through the new materials are introduced, which play important roils in the aeroengine bearing developments. The integration design ideas and practices are explained to indicate its significant advantages and importance to the aerospace engine bearings. And the reliability of the shaft-bearing system is pointed out and treated as the key requirement with goals for both engine and bearing. Finally, as it is believed that the correct design comes from practice, the pre-qualification rig testing conducted by FAG Aerospace GmbH & Co. KG is briefly illustrated as an example. All these lead to the development trends of aerospace engine bearings from different aspects. 展开更多
关键词 aerospace engine bearing performance characteristic material technology integrated bearing design reliability system cost
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Characteristics and Performance of Novel Water-Absorbent Slow Release Nitrogen Fertilizers 被引量:25
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作者 HE Xu-sheng LIAO Zong-wen +4 位作者 HUANG Pei-zhao DUAN Ji-xian GE Ren-shan LI Hong-bo GENG Zeng-chao 《Agricultural Sciences in China》 CAS CSCD 2007年第3期338-346,共9页
In this article, a research on the characteristics and performance of water-absorbent slow release nitrogen fertilizer (WASRNF) using infrared spectroscopy (IR), scanning electronic microscopy (SEM), differentia... In this article, a research on the characteristics and performance of water-absorbent slow release nitrogen fertilizer (WASRNF) using infrared spectroscopy (IR), scanning electronic microscopy (SEM), differential scanning calorimetry (DSC), and thermogravimetry analysis (TGA), was present. The results indicate that the water absorbency and nitrogen analysis of WASRNF is 103 g g^-1 and 30%, respectively, and WASRNF exhibits approximately neutral pH and very low salt index. WASRNF is a copolymer of nitrogen fertilizer and super absorbent polymer (SAP) monomers which is formed through hydrogen bond interaction, and the molecule contains hydrophilic groups, which is responsible for the absorption and water retention capacity of the molecule. WASRNF is a gel that exhibits the ability to swell, but does not dissolve in water. WASRNF shows non-homogenous nature as a whole, but in local zone it is homogenous, the copolymer molecule shows chain network that is the physical structure responsible for absorption and retention of water in WASRNF. The water retained in WASRNF exists as free and nonfreezing bound and freezing bound water states, with the free and the nonfreezing water accounting for more than 95% of water retained in WASRNF, and the nonfreezing bound water for less than 5%. WASRNF functions in delaying the release of nitrogen from it, thereby serving a novel slow release nitrogenous fertilizer. 展开更多
关键词 water-absorbent slow release nitrogen fertilizer characteristics performance
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Experimental study on atomization characteristics and dust-reduction performance of four common types of pressure nozzles in underground coal mines 被引量:5
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作者 Han Han Pengfei Wang +1 位作者 Ronghua Liu Chang Tian 《International Journal of Coal Science & Technology》 EI 2020年第3期581-596,共16页
Pressure nozzle is commonly used in the dust-reduction techniques by spraying of underground coal mines.Based on the internal structure,the pressure nozzle can be divided into the following types:spiral channel nozzle... Pressure nozzle is commonly used in the dust-reduction techniques by spraying of underground coal mines.Based on the internal structure,the pressure nozzle can be divided into the following types:spiral channel nozzle,tangential flow-guided nozzle and X-swirl nozzle.In order to provide better guidance on the selection of nozzles for the coal mine dust-reduction systems by spraying,we designed comparing experiments to study the atomization characteristics and dust-reduction performance of four commonly used nozzles in the coal mine underground with different internal structures.From the experimental results on the atomization characteristics,both the tangential flow-guided nozzle and the X-swirl nozzle have high flow coefficients.The atomization angle is the largest in the spiral non-porous nozzle,and smallest in both the X-swirl nozzle and the spiral porous nozzle.The spraying range and the droplet velocity are inversely proportional to the atomization angle.When the water pressure is low,the atomization performance of the spiral non-porous nozzle is the best among the four types of nozzles.The atomization performance of the X-swirl nozzle is superior to other types when the water pressure is high.Under the high water pressure,the particle size of the atomized droplets is smallest in the X-swirl nozzle.Through the experiments on the dust-reduction performance of the four types of nozzles and the comprehensive analysis,the X-swirl nozzle is recommended for the coal mine application site with low water pressure in the dust-reduction system,while at the sites with high water pressure,the spiral non-porous nozzle is recommended,which has the lowest water consumption and obvious economic advantages. 展开更多
关键词 Pressure nozzle Atomization characteristics Dust-reduction performance Droplets DUST
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Analysis of the design and performance characteristics of pumpable roof supports 被引量:4
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作者 Batchler Timothy 《International Journal of Mining Science and Technology》 SCIE EI CSCD 2017年第1期91-99,共9页
Pumpable roof supports are currently being used to provide a safe working environment for longwall mining. Because different pumpable supports are visually similar and installed fundamentally in the same manner as oth... Pumpable roof supports are currently being used to provide a safe working environment for longwall mining. Because different pumpable supports are visually similar and installed fundamentally in the same manner as other supports, there is a tendency to believe they all perform the same way. However, there are several design parameters that can affect their performance, including the cementitious material properties and the bag construction practices that influence the degree of confinement provided. A full understanding of the impact of these design parameters is necessary to optimize the support application and to provide a foundation for making further improvements in the support performance. This paper evaluates the impact of various support design parameters by examining full-scale performance tests conducted using the National Institute for Occupational Safety and Health(NIOSH) Mine Roof Simulator(MRS) as part of manufacturers' developmental and quality control testing. These tests were analyzed to identify correlations between the support design parameters and the resulting performance. Based on more than 160 tests over 7 years, quantifiable patterns were examined to assess the correlation between the support dimensions, cementitious material type, wire pitch, and single-wall vs. dualwalled bag designs to the support capacity, stiffness, load shedding events, and yield characteristics. 展开更多
关键词 Pumpable Roofsuppo performance characteristics Secondary support
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