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Effects of Biomimetic Surface Designs on Furrow Opener Performance

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Journal of Bionic Engineering 2009年第3期6卷 280-289页

作者： Ballel.Z.Moayad Department of Agricultural Engineering University of Kordofan

The effects of biomimetic designs of tine furrow opener surface on equivalent pressure and pressure in the direction of motion on opener surface against soil were studied by finite element method (FEM) simulation and the effects of these designs on tool force and power requirements were examined *** structures of the cuticle surfaces of dung beetle (Copris ochus Motschulsky) were examined by *** structures of the cuticle surfaces and Ultra High Mo- lecular Weight Polyethylene (UHMWPE) material were modeled on surface of tine furrow opener as biomimetic *** furrow openers were analyzed in ANSYS program (a FEM simulation software).The biomimetic furrow opener surfaces with UHMWPE structures were found to have lower equivalent pressure and pressure in the direction of motion as compared to the conventional surface and to the biomimetic surfaces with textured steel-35 *** was found that the tool force and power were increased with the cutting depth and operating speed and the biomimetic furrow opener with UHMWPE tubular section ridges showed the lowest resistance and power requirement against soil..

关键词： furruw opener UHMWPE biomimetic surface design tillage resistance finite element analysis

Epidemic threshold influenced by non-pharmaceutical interventions in residential university environments

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Chinese Physics B 2024年第2期33卷 551-556页

作者：卢泽超赵生妹束华中巩龙延 Institute of Signal Processing and Transmission Nanjing University of Posts and TelecommunicationsNanjing 210003China College of Science Nanjing University of Posts and TelecommunicationsNanjing 210003China

The control of highly contagious disease spreading in campuses is a critical *** residential universities,students attend classes according to a curriculum schedule,and mainly pack into classrooms,dining halls and *** move from one place to *** simulate such environments,we propose an agent-based susceptible–infected–recovered model with time-varying heterogeneous contact *** close environments,maintaining physical distancing is the most widely recommended and encouraged non-pharmaceutical *** can be easily realized by using larger classrooms,adopting staggered dining hours,decreasing the number of students per dorm and so *** real-world influence remains *** numerical simulations,we obtain epidemic *** effect of such countermeasures on reducing the number of disease cases is also quantitatively evaluated.

关键词： epidemic threshold susceptible-infected-recovered model non-pharmaceutical interventions time-varying heterogeneous contact networks

Technology-Supported university Teaching Models in China During the Pandemic:National Survey and Future Prospects

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ECNU Review of Education 2024年第1期7卷 174-181页

作者：汪潇潇郭双双 Tsinghua university

●The Ministry of Education Research Center for Online Education conducted a national survey of university administrators of learning and teaching.●The survey results showed that(a)the universities in eastern China had developed and introduced more massive open online courses(MOOCs)than those in the central and western regions;(b)of the various measures for blended learning,the universities tended to focus on supporting hardware development before providing training and incentive measures to teachers;and(c)the universities had widely used hybrid learning *** relation to hybrid learning,Tsinghua university explored infrastructure upgrades,teacher training,and the optimal use of the rain classroom and its clone class,and launched the global hybrid classroom and global open courses.●In the future,it will be necessary to further promote education equity in line with national policies and provide and perfect incentives to improve the quality of blended learning and expand hybrid learning while improving interaction through technology.

关键词： Blended learning hybrid learning MOOCs

A Novel Disturbance Observer Based Fixed-Time Sliding Mode Control for Robotic Manipulators With Global Fast Convergence

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IEEE/CAA Journal of Automatica Sinica 2024年第3期11卷 661-672页

作者： Dan Zhang Jiabin Hu Jun Cheng Zheng-Guang Wu Huaicheng Yan IEEE Zhejiang university of Technology Guangxi Normal university Zhejiang university the East China university of Science and Technology

This paper proposes a new global fixed-time sliding mode control strategy for the trajectory tracking control of uncertain robotic ***,a fixed-time disturbance observer(FTDO) is designed to deal with the adverse effects of model uncertainties and external disturbances in the manipulator *** an adaptive scheme is used and the adaptive FTDO(AFTDO) is developed,so that the priori knowledge of the lumped disturbance is not ***,a new non-singular fast terminal sliding mode(NFTSM) surface is designed by using an arctan function,which helps to overcome the singularity problem and enhance the robustness of the *** on the estimation of the lumped disturbance by the AFTDO,a fixed-time non-singular fast terminal sliding mode controller(FTNFTSMC)is developed to guarantee the trajectory tracking errors converge to zero within a fixed *** settling time is independent of the initial state of the *** addition,the stability of the AFTDO and FTNFTSMC is strictly proved by using Lyapunov ***,the fixed-time NFESM(FTNFTSM) algorithm is validated on a 2-link manipulator and comparisons with other existing sliding mode controllers(SMCs) are *** comparative results confirm that the FTNFTSMC has superior control performance.

关键词： Disturbance observer(DO) fixed-time non-singular sliding mode control robotic manipulator trajectory tracking

Petrogenesis and Significance of the Jebel Dumbier Alkaline-Carbonatite Complex from North Margin of Nuba Mountains, Sudan

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Acta Geologica Sinica(English Edition) 2017年第S1期91卷 94-95页

作者： WANG Lianxun MA Changqian MUSA A.S. Mushaal ABDALLSAMED I.M. Mohammmed China university of Geosciences (Wuhan) university of kordofan

1 Introduction Scientific study of the geology and mineral resources in Sudan is rather *** Dumbier is the first identified carbonatite-bearing alkaline complex in Sudanby El Sharkawi&El Raba’a in *** is located in N... 详细信息

关键词： more Sudan Petrogenesis and Significance of the Jebel Dumbier Alkaline-Carbonatite Complex from North Margin of Nuba Mountains

Investigation on occupant presence and appliance operation schedules for university campus in south China sub-tropical area

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Building Simulation 2024年第2期17卷 301-318页

作者： Siwei Lou Zhongyuan Lin Yukai Zou Dawei Xia Yu Huang Zhuohong Li Zhaowen Gu School of Civil Engineering Guangzhou UniversityGuangzhou Higher Edu.Mega CenterGuangzhouChina School of Architecture and Urban Planning Guangzhou UniversityGuangzhou Higher Edu.Mega CenterGuangzhouChina

Building occupant presence during varying periods is crucial to the performance studies of buildings and city ***,the understanding of the building occupancies on the university campus remains *** address this gap,our study employs field measurements,payment records,course arrangements,and building access systems to depict the occupancy patterns of the canteen,dormitory,library,and teaching and lab buildings during weekdays and *** found that the occupancy rates across different buildings are somehow interrelated,given that the total number of occupants on campus is generally ***,dormitory occupancy rates tend to be low during the morning and afternoon course hours,which inversely correlates with the high occupancy rates in the teaching and lab buildings during these ***,canteens experience surges in occupancy during meal times,which coincide with a decrease in library ***,we established appliance operation schedules for dormitories through surveys and on-site *** dispensers and electronic devices were identified as the primary energy consumers for both male and female occupants,with desk-top fans and hairdryers being significant energy users for male and female occupants,*** findings are essential for energy studies within a campus setting,underlining the importance of considering occupant behaviors on a regional scale.

关键词： building occupant behavior university campus occupancy schedule appliance operation schedule

Relationship between physical activity and specific working memory indicators of depressive symptoms in university students

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World Journal of Psychiatry 2024年第1期14卷 148-158页

作者： Qun Zhao Xing Wang Shu-Fan Li Peng Wang Xiang Wang Xin Xin Suo-Wang Yin Zhao-Song Yin Li-Juan Mao School of Physical Education Shanghai University of SportShanghai 200438China Department of Physical Education Donghua UniversityShanghai 201620China

BACKGROUND The detection rate of depression among university students has been increasing in recent years,becoming one of the main psychological diseases that endangers their physical and mental *** to statistics,self-harm and suicide,for which there is no effective intervention,are the second leading causes of *** To explore the relationship between different elements and levels of physical activity and college students’depression-symptom-specific working memory *** Of 143 college students were analyzed using the Beck Depression Self-Rating Scale,the Physical Activity Rating Scale,and the Working Memory *** There was a significant difference between college students with depressive symptoms and healthy college students in completing verbal and spatial working memory(SWM)tasks correctly(all P0.05).CONCLUSION An increase in physical exercise among college students,particularly medium-and high-intensity exercise and exercise of 30 min or more,can improve the correct rate of completing working memory tasks.

关键词： Physical activity Depression symptoms university students Working memory

Synthetic brochosomes:Design,synthesis,and applications

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Nano Research 2024年第2期17卷 734-742页

作者： Lin Wang Jinsol Choi Tak-Sing Wong Department of Mechanical Engineering The Pennsylvania State UniversityUniversity ParkPA 16802USA Materials Research Institute The Pennsylvania State UniversityUniversity ParkPA 16802USA Department of Biomedical Engineering The Pennsylvania State UniversityUniversity ParkPA 16802USA

Brochosomes,which are nanoscopic buckyball-shaped granules produced by leafhoppers,are one of the most intricate structures discovered in *** functions of brochosomes have been proposed but only a few have been experimentally validated due to the challenge of fabricating their synthetic *** in micro-and nanofabrication have recently led to the emergence of synthetic brochosomes,opening up new possibilities for innovative *** review explores the early discovery of natural brochosomes and their geometrical features,followed by the recent progress in fabricating synthetic brochosomes and their *** on future applications and challenges in the scalable manufacturing of synthetic brochosomes are discussed.

关键词： synthetic brochosomes leafhopper antireflection superhydrophobicity surface-enhanced Raman scattering photocatalyst energy harvesting

Analysis of synthetic parameters for coating aluminum powders with phenyltriethoxysilane coupling agent and their effects on powder flow behavior

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Particuology 2024年第7期90卷 412-417页

作者： Lillian M.Mawby Bellamarie Ludwig Benjamin J.Lear Department of Chemistry The Pennsylvania State UniversityUniversity ParkPA16802USA Applied Research Laboratory The Pennsylvania State UniversityUniversity ParkPA16802USA

Though silanization of aluminum powder is currently used to improve its flow properties,for use as an alternative fuel source,there are a wide range of experimental parameters for the process and not all of them have been thoroughly *** this is complete,it is unknown if the process is optimized in terms of time,efficiency,and ***,we report on a study into the effects of changes in humidity,degree of agitation,reaction temperature,and curing time upon the deposition of phenyl triethoxysilane into 20μm(d50)aluminum *** confirm the deposition of the coating via diffuse reflectance infrared spectroscopy and x-ray photoelectron *** then characterize the coated particles using apparent density measurements and Carney flow *** analysis of variance,we find that,of the parameters explored,only changes in cure time and reaction temperature provide meaningful changes to the apparent density,while none of our parameters produced statistically significant changes in Carney flow ***,we conclude that,when optimizing silanization of aluminum particles,environmental control of humidity is unneeded and that the reaction can be run with minimal *** ability to largely ignore these parameters is a benefit to large-scale processing.

关键词： Aluminum powder Silane Fluidization Apparent density Carney flow