检索结果-南通市图书馆

Anti-saturation fault-tolerant adaptive torsional vibration control with fixed-time prescribed performance for rolling mill main drive system

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 Iron and Steel Research International 2024年第3期31卷 660-669页

作者： Shuang liu Chen Du Cong Zhang Zhen-hua Bai Key Lab of Industrial Computer Control Engineering of Hebei Province Yanshan UniversityQinhuangdao 066004HebeiChina National Engineering Research Center for Equipment and Technology of Cold Strip Rolling Yanshan UniversityQinhuangdao 066004HebeiChina

An anti-saturation fault-tolerant adaptive torsional vibration control method with fixed-time prescribed performance for the rolling mill main drive system(RMMDS)was investigated,which is affected by control input saturation,actuator faults,sensor measurement errors,and parameter ***,we gave a continuously differentiable saturation function to approximate the control input saturation characteristic of the RMMDS,translating the saturation characteristic into the matched uncertainty and unknown time-varying gain in the ***,an RMMDS mathematical model with unmatched uncertainty and unknown time-varying gain was developed,taking into account the presence of control input saturation,actuator faults,sensor measurement errors,and parameter *** on the established mathematical model,an error transformation model of the roll speed tracking was constructed by the equivalent error transformation *** to the error transformation model,a barrier Lyapunov function and a novel adaptive controller were studied to ensure that the roll speed tracking error always evolves inside a fixed-time asymmetric ***,numerical simulations were performed in Matlab/Simulink to verify the effectiveness and superiority of the proposed control method in suppressing the RMMDS torsional vibration.

关键词： Fixed-time prescribed performance Control input saturation Actuator fault Unknown time-varying gain Adaptive control Asymmetric constraint

Asymmetric reversible structural switching of a diene coordination polymer promoted by UV-visible light

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China Chemistry 2024年第2期67卷 536-541页

作者： yong Wang Qiaoqiao Zhang yong-yong Cao Qi liu Brendan F.Abrahams Jian-Ping Lang College of Chemistry Chemical Engineering and MaterialsSoochow UniversitySuzhou215123China State Key Laboratory of Organometallic Chemistry Shanghai Institute of Organic ChemistryChinese Academy of SciencesShanghai200032China College of Biological Chemical Science and EngineeringJiaxing UniversityJiaxing314001China School of Chemistry University of MelbourneVictoria3010Australia

In natural and artificial systems,reversible reactions are commonly asymmetric with respect to the time scale and nature of the stimuli which drive the forward and backward *** applications for which switching behavior is required,it is desirable that the reversible reaction goes as close to symmetric as possible;however,such systems are ***,we report an example of ultraviolet(UV)-visible light-regulated asymmetric reversible structural switching involving a diene-based coordination polymer,CP1 and its monocyclobutane product,*** is possible to cycle at least ten times through a forward [2+2] photocycloaddition reaction and the reverse,photocleavage reaction.A single cycle can be completed within a few *** transformation is accompanied by fast and distinct fluorescence changes,arising from optimisation of the reaction *** functional theory calculations allow rationalisation of the asymmetric reversible transformation between CP1 and CP1a rather than between CP1 and its dicyclobutane product *** work provides a clear illustration of reversible structural switching which approaches symmetric behaviour with respect to reaction rate and *** insights gained from this work also assist in the design of fast,reversible switching materials.

关键词： asymmetrical reversible structural switching coordination polymer photocycloaddition UV-visible light-controlled fluorescence switching

在线全文

学校读者我要写书评

暂无评论

动叶可调地铁风机研究

流体机械 2018年第5期46卷 25-30页

作者：刘华永中铁第一勘察设计院集团有限公司广东广州510330

用CFX软件对原地铁风机DTF18#(排热风机)的气动性能进行了数值模拟,并通过与试验结果对比验证了数值模拟方法的可靠性。在此基础上,基于风机运行要求,对该风机的叶片造型、导流罩型线进行优化与分析,并对动叶安放角、动叶数和导叶数进... 详细信息

用CFX软件对原地铁风机DTF18#(排热风机)的气动性能进行了数值模拟,并通过与试验结果对比验证了数值模拟方法的可靠性。在此基础上,基于风机运行要求,对该风机的叶片造型、导流罩型线进行优化与分析,并对动叶安放角、动叶数和导叶数进行调整,扩大风机工作区范围,以满足设计要求。结果表明,计算值和实测值基本吻合。最终优化的风机流量、压力均达到设计要求,风机最高效率为85.2%,较原DTF18#风机效率提高了15.3%,达到一级能效。

关键词：地铁风机数值模拟优化设计高效模型开发

Evaluation of suitability,adaptability,and reserve potential of construction land on the Qinghai-Tibet Plateau

在线全文

学校读者我要写书评

暂无评论

Journal of Geographical Sciences 2024年第1期34卷 41-61页

作者： YANG hua XU yong ZHOU Kan WANG Lijia XU Lin Key Laboratory of Regional Sustainable Development Modeling Institute of Geographic Sciences and Natural Resources ResearchCASBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China

Construction land is the leading carrier of human activities such as production and *** the construction land suitability(CLS)on the Qinghai-Tibet Plateau(QTP)holds significant implications for harmonizing the relationship between ecological protection and human activity and promoting population and industry layout ***,no relevant studies provide a complete CLS assessment of the *** this study,we developed a model-based CLS evaluation framework coupling of pattern and process to calculate the global CLS on the QTP based on a previously developed CLS evaluation ***,using the land-use data of 1990,2000,2010,and 2020,we examined the adaptability of existing construction land(ECL)to the CLS assessment result through the adaptability index and vertical gradient index and further analyzed the limitations of maladaptive construction ***,we calculated the potential area of reserve suitable construction *** article includes four conclusions:(1)The highly suitable,suitable,moderately suitable,marginally suitable,and unsuitable CLS classes cover areas of 0.33×10^(4)km^(2),10.42×10^(4)km^(2),18.06×10^(4)km^(2),24.12×10^(4)km^(2),and 205.29×10^(4)km^(2),*** approximately 11%of the study area on the QTP is suitable for large-scale permanent construction land,and approximately 79.50%of the area is unsuitable under current economic and technological conditions.(2)The ECL adaptability index is 85.16%,85.93%,85.18%,and 78.01%during 1990–2020,respectively,with an average adaptability index exceeding 80%on the *** ECL distribution generally conforms to construction land suitable space characteristics but with a significant spatial difference.(3)From 1990 to 2020,the maladaptive ECL was dominated by rural settlement land,transport land,and special land,with a rapidly increasing proportion of urban and other construction *** maladaptive ECL is constrained by both elevation and slope in the southern Qinghai Pla

关键词： land resource construction land suitability existing construction land adaptability human activity Qinghai-Tibet Plateau

Three-stage niobium mineralization at Bayan Obo, China

在线全文

学校读者我要写书评

暂无评论

National Science Review 2024年第4期11卷 102-110页

作者： Yan Yu Yang Li Yu liu Xiao-Xiao Ling Li-Guang Wu Li Yang Lan Yang Bo Yang yong-Gang Zhao Xian-hua Li State Key Laboratory of Lithospheric Evolution Institute of Geology and Geophysics Chinese Academy of Sciences College of Earth and Planetary Science University of Chinese Academy of Sciences Ministry of Education Key Laboratory of Orogenic Belts and Crustal Evolution School of Earth and Space SciencesPeking University Mining Research Institute Baotou Iron and Steel(Group) Co.LTD State Key Laboratory of Baiyunobo Rare Earth Resource Research and Comprehensive Utilization

The Chinese Bayan Obo deposit is a world-class rare earth element(REE) deposit with considerable niobium(Nb) and iron(Fe) resources. A complete genetic understanding on all metals is fundamental for establishing genetic models at Bayan Obo. With extensive research being focused on REE enrichment, the timing and controls of Nb enrichment remain unresolved at Bayan Obo, which is mainly due to the challenges in dating, i.e. multistage thermal events, fine-grained minerals with complex textures and the rare occurrence of uranium-enriched minerals with mature dating methods. Based on robust geological and petrographic frameworks, here we conducted ion probe uranium-lead(U-Pb) dating of ferrocolumbite to unravel the timing, hence the genesis of Nb mineralization. Three types of hydrothermal ferrocolumbites—key Nb-bearing minerals—are identified based on their textures and mineral assemblages. They yield U-Pb ages of 1312 ± 47 Ma(n = 99), 438 ± 7 Ma(n = 93), and 268 ± 5 Ma(n = 19), respectively. In line with deposit geology, we tentatively link the first, second and third stage Nb mineralization to Mesoproterozoic carbonatite magmatism, ubiquitous early Paleozoic hydrothermal activity, and Permian granitic magmatism, respectively. While quantifying the contribution of metal endowment from each stage requires further investigation, our new dates highlight that multi-stage mineralization is critical for Nb enrichment at Bayan Obo, which may also have implications for the enrichment mechanism of Nb in REE deposits in general.

关键词： niobium mineralization U-Pb dating ferrocolumbite Bayan Obo

Tetraphenylethene-based hole transporting material for highly efficient and stable perovskite solar cells

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China Chemistry 2024年第6期67卷 2009-2015页

作者： Peng Wang Pei Yuan Chenghao Ge Rongjun Zhao Lin Xie yong hua School of Materials and Energy Yunnan UniversityKunming650091China

2,2,7,7-Tetrakis-(N,N-di-p-methoxyphenylamine)-9,9-spirobifluorene(Spiro-OMeTAD)has been identified as the most widely used and effective hole transporting material(HTM)in perovskite solar cells(PSCs).However,the complicated multistep synthesis and low intrinsic hole mobility of Spiro-OMe TAD limit its commercialized ***,developing highly efficient HTMs with less synthetic steps becomes increasingly ***,understanding hot carriers transfer dynamics at the interface of perovskite layer and hole transport layer is crucial for further enhancing PSCs performance towards Shockley-Queisser limit,which still lacks full investigation to ***,a new HTM based on tetraphenylethene(WP1)was successfully synthesized by a simple one-step reaction *** was found that WP1-based HTM exhibits more matched energy level,higher hole mobility and conductivity than those of the control Spiro-OMe *** femtosecond transient absorption results reveal that the transfer rate of hot holes in perovskite/WP1 sample is four times higher than that of perovskite/Spiro-OMeTAD,thereby helping enhance the device ***,the efficiency of PSCs is enhanced to 24.04%(WP1)from 22.85%(Spiro-OMeTAD).Moreover,the un-encapsulated device prepared with WP1 exhibits better long-term stability,retaining 87%of its initial PCE value after storing for 72 days under air environment,while the reference device shows76%of its initial *** work indicates that simple tetraphenylethene-based organic small molecule could be a very promising HTM candidate for highly efficient PSCs,and gives some significant insights for understanding intrinsic hot carriers transfer dynamics in device.

关键词： tetraphenylethene hole transporting material perovskite solar cells mobility hot carrier

Impact and mechanism of bisphosphonate depressant 1-hydroxypropane-1,1-diphosphonic acid on flotation decalcification of dolomite-rich magnesite ore

在线全文

学校读者我要写书评

暂无评论

International Journal of Mining Science and Technology 2024年第7期34卷 1017-1032页

作者： Wengang liu Xudong Chen Wenbao liu Naixu Zhang yong Mao Ying Guo School of Resources&Civil Engineering Northeastern UniversityShenyang 110819China

Given the depletion of high-quality magnesite deposits and the rising demand for high-end magnesium materials,the separation and utilization of high-calcium magnesite ores have become ***,the similar surface properties and solubility of semi-soluble salt-type minerals,pose significant challenges for the utilization of dolomite-rich magnesite *** this study,1-hydroxypropane-1,1-di phosphonic acid(HPDP)was identified for the first time as a high-performance depressant for *** tests,including contact angle measurements,ζ potential analysis,X-ray photoelectron spectroscopy,and atomic force microscopy,were conducted to elucidate the interfacial interaction mechanisms of HPDP on the surfaces of the two minerals at different ***,molecular modeling calculations were used to detail the spatial matching relationship between HPDP and the crystal faces of the two *** was emphasized that HPDP specifically adsorbed onto the dolomite surface by forming calcium phosphonate,ensuring that the dolomite surface remained hydrophilic and ***,it was found that the adsorption strength of HPDP on the mineral surfaces depended on the activity of the metal sites and their spatial *** findings provide a theoretical foundation for the molecular design of flotation reagents for high-calcium magnesite ores.

关键词： Depressant Interfacial mechanism Magnesite Dolomite DFT Decalcification

Using Copula functions to predict climatic change impacts on floods in river source regions

在线全文

学校读者我要写书评

暂无评论

Advances in Climate Change Research 2024年第3期15卷 406-418页

作者： Ting-Xing CHEN Hai-Shen LYU Robert HORTON yong-hua ZHU Ren-Sheng CHEN Ming-Yue SUN Ming-Wen liu Yu LIN The National Key Laboratory of Water Disaster Prevention College of Hydrology and Water ResourcesHohai UniversityNanjing 2098China College of Hydrology and Water Resources Hohai UniversityNanjing 210098China Departmentof Agronomy lowa State UniversityAmes IA5oollUSA Qilian Alpine Eology and Hydrology Research Station Northwest Instiuteof Eco-Environmentand ReourcesChinese Academy of SciencesLanzhou0000 China

Flood frequency in river source regions is significantly affected by rainfall and snowmelt as part of climatic changes.A traditional univariate flood frequency analysis cannot reflect the complexity of floods,and when used in isolation,it can only underestimate flood *** effective flood prevention and mitigation,it is essential to consider the combined effects of precipitation and *** functions can effectively quantify the joint distribution relationship between floods and their associated variables without restrictions on their distribution *** study uses copula functions to consider a multivariate probability distribution model of flood peak flow(Q)with cumulative snowmelt(CSm)and cumulative precipitation(CPr)for the Hutubi River basin located in northern Xinjiang,*** joint frequencies of rainfall and snowmelt floods are predicted using copula models based on the Coupled Model Intercomparison Project Phase 6 *** results show that Q has a significant positive correlation with 24-d CSm(r=0.559,p=0.002)and 23-d CPr(r=0.965,p<0.05).Flood frequency will increase in the future,and mid-(2050e2074)and long-term(2075e2099)floods will be more severe than those in the near-term(2025e2049).The probability of flood occurrence is higher under the SSP2-4.5 and SSP1-2.6 scenarios than under *** during the historical period(1990e2014)led to extreme floods,and increasing future precipitation trends are found to be *** increases with rising temperatures and occurs earlier than estimated,leading to an earlier flood period in the basin and more frequent snowmelt *** Q under the joint return period is larger than that during the same univariate return *** difference indicates that neglecting the interaction between precipitation and snowmelt for floods leads to an underestimation of the flood risk(with underestimations ranging from 0.3%to 22%).The underestimations decrease with an increase

关键词： Climate change Flood frequency Copula CMIP6 River source regions

A novel multi-state bogie system reliability evaluation approach by extended d-MC model for high-speed trains

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Transportation Safety and Environment 2024年第3期6卷 35-46页

作者： yong Fu Ruoqu liu Jisheng Dai Wenlong Zhu Xin liu yong Qin Zhuzhou CRRC Times Electric Co. Ltd.Times RoadShifeng DistrictZhuzhouHunan 412001China Department of Statistics University of WarwickCoventry CV47ALUnited Kingdom State Key Lab of Rail Traffic Control&Safety Beijing Jiaotong UniversityHaidian DistrictBeijing 100044China

Bogie is a pivotal system and plays a critical part in the safety and reliability management of high-speed ***,the available bogie system reliability analysis methods lack the consideration of multi-state characteristics,and the common multi-state reliability analysis methods,being an NP-hard problem,lead to low *** order to overcome these drawbacks,this paper proposes a novel multi-state rail train bogie system reliability analysis approach based on the extended d-MC *** different function interactions within the bogie system are considered to build the multi-state bogie system flow network ***,an extended d-MC model is established to remove unnecessary d-MC candidates and duplicates,which greatly enhances the computing *** bogie system reliability is calculated,and examples are *** experiments are carried out for the different operational conditions of the bogie system and are used to test the practicability of the method proposed in this article;it is found that this method outperforms a newly developed method in solving multi-state reliability problems.

关键词： multi-state system reliability bogie flow network extended d-MC model