检索结果-南通市图书馆

Friction 2023年第4期11卷 580-601页

作者： Shuai gao Qinkai HAN Paolo PENNACCHI steven CHATTERTON Fulei CHU Department of Mechanical Engineering Politecnico di MilanoVia G.La Masa 1Milan 20156Italy State Key Laboratory of Tribology Department of Mechanical EngineeringTsinghua UniversityBeijing 100084China

The term“over-skidding”indicates that the cage rotational speed ratio exceeds the theoretical value as ball purely rolls on the *** from the skidding phenomenon that occurs in low-load and high-speed bearing,over-skidding usually occurs in large-size angular contact bearings,and it is still difficult to suppress under high load *** main forms of damage to the raceway by over-skidding are spinning and gyro *** further explore the vibration characteristics and thermal effects of this phenomenon,a set of over-skidding tests of an angular contact bearing with a bore diameter of 220 mm were conducted on an industrial-size test *** the experiment,the influence of axial load,rotational speed,and lubrication conditions on the occurrence of over-skidding were *** on a previous dynamics model,the heat generation and thermal network models were integrated in the present study to predict the over-skidding and its thermal *** model was validated in terms of the measured degree of over-skidding and temperature *** results showed that the degree of over-skidding reaches up to 12%of the theoretical value,and the friction power loss of the ball-pocket accounts for 30%of the total power *** analysis of the vibration signal showed a strong correlation between the bearing vibration characteristics and over-skidding behavior,thereby providing a way to indirectly measure the degree of over-skidding.

关键词： over-skidding vibration characteristics dynamic model power loss temperature rise

Volterra filter modeling of a nonlinear discrete-time system based on a ranked differential evolution algorithm

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science C(Computers and Electronics) 2014年第8期15卷 687-696页

作者： De-xuan ZOU Li-qun gao steven LI School of Electrical Engineering and Automation Jiangsu Normal University School of Information Science and Engineering Northeastern University Graduate School of Business and Law RMIT UniversityGPO Box 2476 Melbourne 3001 Australia

This paper presents a ranked differential evolution(RDE) algorithm for solving the identification problem of nonlinear discrete-time systems based on a Volterra filter model. In the improved method, a scale factor, generated by combining a sine function and randomness, effectively keeps a balance between the global search and the local search. Also, the mutation operation is modified after ranking all candidate solutions of the population to help avoid the occurrence of premature convergence. Finally, two examples including a highly nonlinear discrete-time rational system and a real heat exchanger are used to evaluate the performance of the RDE algorithm and five other approaches. Numerical experiments and comparisons demonstrate that the RDE algorithm performs better than the other approaches in most cases.

关键词： Ranked differential evolution Identification problem Nonlinear discrete-time systems Volterra filter model Premature convergence

A review of chatter vibration research in milling

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2019年第2期32卷 215-242页

作者： Caixu YUE Haining gao Xianli LIU steven Y.LIANG Lihui WANG Harbin University of Science and Technology Georgia Institute of Technology KTH Royal Institute of Technology

Chatter is a self-excited vibration of parts in machining systems. It is widely present across a range of cutting processes, and has an impact upon both efficiency and quality in production processing. A great deal of research has been dedicated to the development of technologies that are able to predict and detect chatter. The purpose of these technologies is to facilitate the avoidance of chatter during cutting processes, which leads to better surface precision, higher productivity,and longer tool life. This paper summarizes the current state of the art in research regarding the problems of how to arrive at stable chatter prediction, chatter identification, and chatter control/-suppression, with a focus on milling processes. Particular focus is placed on the theoretical relationship between cutting chatter and process damping, tool runout, and gyroscopic effect, as well as the importance of this for chatter prediction. The paper concludes with some reflections regarding possible directions for future research in this field.

关键词： Chatter Gyroscopic effects Milling Process damping Tool runout

Lateral detrital C transfer across a Spartina alternifora invaded estuarine wetland

在线全文

学校读者我要写书评

暂无评论

Ecological Processes 2021年第1期10卷 980-998页

作者： Yu gao Jiquan Chen Tingting Zhang Bin Zhao steven McNulty Haiqiang Guo Feng Zhao Ping Zhuang Key Laboratory of East China Sea&Oceanic Fishery Resources Exploitation and Utilization Scientifc Observing and Experimental Station of Fisheries Resources and Environment of East China Sea and Yangtze EstuaryEast China Sea Fisheries Research InstituteChinese Academy of Fishery SciencesShanghai 200090China. Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering Coastal Ecosystems Research Station of the Yangtze River Estuaryand Institute of Eco-Chongming(IEC)Fudan UniversityShanghai 200438China. Department of Geological Sciences University of Texas at AustinAustinTX 78712USA. Department of Geography and Center for Global Change and Earth Observations(CGCEO) Michigan State UniversityEast LansingMI 48824USA. Eastern Forest Environmental Threat Assessment Center Southern Research StationUSDA Forest ServiceResearch Triangle ParkNC 27709USA.

Background:The lateral movements of mass and energy across the terrestrial-aquatic interface are being increasingly recognized for their importance in the carbon(C)balance of coastal/estuarine *** quantifed the lateral fux of detrital C in the Yangtze estuary where invasive Spartina alternifora has substantially and extensively altered the ecosystem structure and *** overall objective was to close the C budget of estuarine wetlands through feld sampling,tower-based measurements,and ***:A lateral detrital C exchange evaluation platform was established in a case study of the Yangtze River Estuary to investigate the efect of ecosystem structural changes on lateral detrital C transfer *** study estimated the lateral detrital C exchange based on the gross primary production(GPP)by performing coupled modeling and feld ***-based measurements and MODIS time series and CH4 outgassing and biomass simultaneously measured the lateral detrital C fux to characterize the relative contributions of lateral(i.e.,detritus)C fuxes to the annual marsh C ***:The C pools in the plants and soil of Spartina marshes were signifcantly higher than those of the native community dominated by Phragmites *** GPP based on MODIS(GPPMODIS)was 472.6 g C m^(−2) year^(−1) and accounted for 73.0%of the GPP estimated from eddy covariance towers(GPPEC)(646.9±70.7 g C m^(−2) year^(−1)).We also detected a higher GPPMODIS during the pre-growing season,which exhibited a similar lateral detrital C fux *** average,25.8%of the net primary production(NPP),which ranged from 0.21 to 0.30 kg C m^(−2) year^(−1),was exported during lateral *** annual C loss as CH4 was estimated to be 17.9±3.7 g C m^(−2) year^(−1),accounting for 2.8%of the *** net positive detrital C fux(i.e.,more detritus leaving the wetlands),which could exceed 0.16 kg C m^(−2) day^(-1),was related to daily ***,the observed lateral detrital C fu

关键词： Estuarine wetland Carbon outwelling Lateral carbon fux Methane emission Spartina alternifora Phragmites australis

A refutation of reported Levallois technology from Guanyindong Cave in south China

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

National Science Review 2019年第6期6卷 1094-1096页

作者： Feng Li Yinghua Li Xing gao steven L.Kuhn Eric Boёda John W.Olsen Key Laboratory of Vertebrate Evolution and Human Origins of the Chinese Academy of Sciences Institute of Vertebrate Paleontology and Paleoanthropology Chinese Academy of Sciences CAS Center for Excellence in Life and Paleoenvironment School of History Wuhan University University of Chinese Academy of Sciences School of Anthropology University of Arizona C.N.R.S.-UMR7041 Anthropologie des techniques des espaces et des territoires au Plio-Pléistocène Maison Archéologie et Ethnologie

As one of the most complex forms of lithic technology known for the Paleolithic, research on the Levallois stoneknapping method is critically relevant to our understanding of the cognitive abilities and depth of planning capabilities of archaic hominins, as well as the diffusion of knowledge and social learning in Pleistocene societies. For decades,

关键词： A refutation of reported Levallois technology from Guanyindong Cave in south China

Photothermal superhydrophobic copper nanowire assemblies: fabrication and deicing/defrosting applications

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

International Journal of Extreme Manufacturing 2023年第4期5卷 472-484页

作者： Siyan Yang Qixun Li Bingang Du Yushan Ying Yijun Zeng Yuankai Jin Xuezhi Qin Shouwei gao steven Wang Zuankai Wang Rongfu Wen Xuehu Ma State Key Laboratory of Fine Chemicals&Frontier Science Center for Smart Materials School of Chemical EngineeringDalian University of TechnologyDalian 116024People’s Republic of China Department of Mechanical Engineering City University of Hong KongHong Kong 999077People’s Republic of China Department of Mechanical Engineering The Hong Kong Polytechnic UniversityHong Kong 999077People’s Republic of China

Ice and frost buildup continuously pose significant challenges to multiple *** a promising de-icing/defrosting alternative,designing photothermal coatings that leverage on the abundant sunlight source on the earth to facilitate ice/frost melting has attracted tremendous attention ***,previous designs suffered from either localized surface heating owing to the limited thermal conductivity or unsatisfied meltwater removal rate due to strong water/substrate ***,we developed a facile approach to fabricate surfaces that combine photothermal,heat-conducting,and superhydrophobic properties into one to achieve efficient de-icing and *** copper nanowire assemblies,such surfaces were fabricated via the simple template-assisted electrodeposition method,allowing us to tune the nanowire assembly geometry by adjusting the template dimensions and electrodeposition *** highly ordered copper nanowire assemblies facilitated efficient sunlight absorption and lateral heat spreading,resulting in a fast overall temperature rise to enable the thawing of ice and *** promoted by the excellent water repellency of the surface,the thawed ice and frost could be spontaneously and promptly *** this way,the all-in-one design enabled highly enhanced de-icing and defrosting performance compared to other nanostructured surfaces merely with superhydrophobicity,photothermal effect,or the combination of *** particular,the defrosting efficiency could approach∼100%,which was the highest compared to previous ***,our approach demonstrates a promising path toward designing highly effective artificial deicing/defrosting surfaces.

关键词： nanowire photothermal superhydrophobic de-icing defrosting

Fleet size estimation for spreading operation considering road geometry,weather and traffic

在线全文

学校读者我要写书评

暂无评论

Journal of Traffic and Transportation Engineering(English Edition) 2014年第1期1卷 1-12页

作者： steven I-Jy Chien Shengyan gao Jay N.Meegoda Taha F.Marhaba Department of Civil & Environmental Engineering New Jersey Institute of Technology School of Automobile Chang'an University

Extreme weather conditions（i, e. snow storm） in winter time have caused significant travel disruptions and increased delay and traffic accidents. Snow plowing and salt spreading are the most common counter-measures for making our roads safer for motorists. To assist highway maintenance authorities with better planning and allocation of winter maintenance re- sources, this study introduces an analytical model to estimate the required number of trucks for spreading operation subjective to pre-specified service time constraints considering road geome- try, weather and traffic. The complexity of the research problem lies in dealing with heteroge- neous road geometry of road sections, truck capacities, spreading patterns, and traffic speeds under different weather conditions and time periods of an event. The proposed model is applied to two maintenance yards with seven road sections in New Jersey （USA）, which demonstrates itself fairly practical to be implemented, considering diverse operational conditions.

关键词： fleet size road geometry road network spreading operation traffic speed winter road maintenance

n-Channel Organic Transistors Processed from Halogen-Free Solvents： Solvent Effect on Thin-Film Morphology and Charge Transport

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemistry 2016年第7期34卷 689-695页

作者： Simin gao Yonghui Hu Zhiming Duan Xike gao Department of Chemistry College of Science Shanghai University Shanghai 200444 China Key Laboratory of Synthetic and Self-Assembly Chemistry for Organic Functional Molecules Shanghai Institute of Organic Chemistry Chinese Academy of Sciences Shanghai 200032 China

Non-chlorinated solvents are highly preferable for organic electronic processing due to their environmentally friendly characteristics. Four different halogen-free solvents, tetrafuran, toluene, meta-xylene and 1,2,4-trimethyl- benzene, were selected to fabricate n-channel organic thin film transistors （OTFTs） based on 3-hexylundecyl sub- stituted naphthalene diimides fused with （1,3-dithiol-2-ylidene）malononitrile groups （NDI3HU-DTYM2）. The OTFTs based on NDI3HU-DTYM2 showed electron mobility of up to 1.37 cm2-V-1·s -1 under ambient condition. This is among the highest device performance for n-channel OTFTs processed from halogen-free solvents. The dif- ferent thin-film morphologies, from featureless low crystalline morphology to well-aligned nanofibres, have a great effect on the device performance. These results might shed some light on solvent selection and the resulting solution process for organic electronic devices.

关键词： organic thin film transistor non-chlorinated solvents electron transport

Chinese Tuina Downregulates the Elevated Levels of Tissue Plasminogen Activator in Sciatic Nerve Injured Sprague-Dawley Rats

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Integrative Medicine 2017年第8期23卷 617-624页

作者： PAN Fan YU Tian-yuan steven Wong XIAN Si-tong LU Meng-qian WU Jian-cong gao Yu-feng LI Xiao-qin GENG Nan YAO Bin-bin Collage of Acupuncture-Moxibustion and Tuina Beijing University of Chinese Medicine The 2nd Massage Department Beijing Massage Hospital Department of Encephalopathy of Mogol Medicine Affiliated Hospital of Inner Mongolia University for the Nationalities Department of Acupuncture and Moxibustion Affiliated Hospital of Jiangxi University of Traditional Chinese Medicine Department of Massage Physiotherapy Beijing University of Chinese Medicine Dongfang Hospital

Objective：To elucidate the mechanism of Chinese tuina in treating sciatic nerve crush injury,and to detect the levels of tissue plasminogen activator（t PA）and plasminogen activator inhibitor-1（PAI-1）,which is thought to play an important role in nerve ***：Thirty-two adult male Sprague-Dawley rats were subjected to sciatic nerve crush injury and 16 rats（sham-operated group）went through a sham *** group was given no treatment while tuina group received tuina therapy since day 7 *** treatment was performed once a day and lasted for 20 *** sciatic functional index was examined every 5days during the treatment *** rats＇gastrocnemius muscles were evaluated for changes in mass and immunohistochemistry techniques were performed to detect the levels of tP A and ***：Tuina therapy improved the motor function of sciatic nerve injured rats（P〈0.05）,however,it did not increase muscle volume（P〈0.05）.Tuina downregulated the levels of t PA and PAI-1（P〈0.05）.Conclusions：The present study implies that tuina treatment could accelerate rehabilitation of peripheral nerve injury.

关键词： Chinese medicine physical therapy peripheral neuropathy massage