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Science China Mathematics 2022年第2期65卷 291-308页

作者： qian yang Mingkang Ni School of Mathematical Sciences East China Normal UniversityShanghai 200241China Shanghai Key Laboratory of Pure Mathematics and Mathematical Practice Shanghai 200241China

A piecewise-smooth second-order singularly perturbed differential equation whose right-hand side is a nonlinear function with a discontinuity on some curve is investigated. This is a new class of problems in the case where the degenerate equation has a multiple root on the left-hand side of the curve which separates the domain and an isolated root on the right-hand side of that curve. The asymptotics of a solution with an internal layer near a point on the discontinuous curve and the transition point is constructed. The method to construct the internal layer function is proposed. The behavior of the solution in the internal layer consisting of four zones essentially differs from the case of isolated roots. For sufficiently small parameter values, the existence of a smooth solution with an internal layer from the multiple root of the degenerate equation to the isolated root in the neighborhood of a point on the discontinuous curve is proved. The method can be shown to be effective in the given example.

关键词： reaction-diffusion equation multizonal internal layer asymptotic method piecewise-smooth dynamical system

Research on the applications of infrared technique in the diagnosis and prediction of diesel engine exhaust fault

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Journal of Thermal Science 2011年第2期20卷 189-194页

作者： Lv Shi-gui yang Li yang qian Department of Power Engineering Naval University of Engineering Wuhan 430033 China

This paper mainly introduces the basic principles,the methods and the applications of infrared technique in the diagnosis and prediction of diesel engine exhaust faults. The test-bed for monitoring diesel engine exhaust faults by thermal infrared imager has been designed. In different running conditions, the exterior surface radiation temperatures of the exhaust pipe of the 6135G-1 diesel engine have been measured by infrared imaging system. According to the principle of infrared temperature measurement, the real temperatures of the exterior surface of the exhaust pipe have been calculated. Based on the principle of heat transfer, the method of calculating the exhaust temperatures according to the exterior surface radiation temperatures of exhaust pipe measured by thermal infrared imager is built. The relationship between diesel engine exhaust temperatures and faults has been analyzed. It is shown that the application of infrared inspection and diagnosis to the identifying of diesel engine exhaust faults is feasible and effective.

关键词： infrared exhaust temperature infrared diagnosis diesel engine fault

PEO-b-P4VP/Yttrium Hydroxide Hybrid Nanotubes as Supporter for Catalyst Gold Nanoparticles

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Chinese Journal of Chemical Physics 2012年第3期25卷 352-358,374页

作者： qian yang Dao-yong Chen The State Key Laboratory of Molecular Engineering of Polymers Department of Macromolecular Sci-ence Fudan University Shanghai 200433 China

The adsorption of poly （ethylene oxide）-b-poly（4-vinylpyridine）（PEO-b-P4VP） micelles onto the surface of yttrium hydroxide nanotubes （YNTs） resulted in the hybrid nanotubes with a dense P4VP inner layer and a stretched PEO outer layer surrounding YNTs. The dense P4VP layer was further stabilized by the crosslinking using 1,4-dibromobutane as the crosslinker. Then, the crosslinked hybrid nanotubes （CHNTs） were used as a novel nano supporter for loading the catalyst gold nanoparticles （GNPs） within the crosslinked P4VP layer. The resultant GNPs/CHNTs （GNTs loaded on CHNTs） were applied to catalyze the reduction reaction of p-nitrophenol. The results indicate that this novel nano supporter has advantages such as good dispersity in the suspension, high capacity in loading GNPs （0.87 mmol/g）, high catalytic activity of the loaded GNPs （12.9 μmol-lmin-i）, and good reusability of GNTs/CHNTs.

关键词： Gold nanoparticle catalyst Block copolymer Hybrid nanotube Reusable p-Nitrophenol

Joint DOA and time delay estimation method for space-time coherent distributed signals based on search

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Journal of Systems Engineering and Electronics 2007年第2期18卷 341-346页

作者： qian Bin yang Wanlin Wan Qun Coll. of Electronic Engineering Univ. of Electronic Science and Technology of China Chengdu 610054 P.R. China

Under dense urban fading environment, performance of joint multi-path parameter estimation method based on traditional point signal model degrades seriously. In this paper, a new space and time signal model based on multipath distribution function is given after new space and time manifold is reconstructed. Then joint spacetime signal subspace is obtained by converting acquired channel from time domain to frequency domain .Then space and time spectrum is formulated by the space sub-matrix and time sub-matrix taken out of joint space-time signal subspace, and parameters are estimated by searching the minimum eigenvalues of the space matrix and the time matrix. Lastly, A space and time parameters matching process is performed by using the orthogonal property between joint noise subspace and the space-time manifold. In contrast with tradition MUSIC, the algorithm we present here only need two 1- dimension searching and was not sensitive to different distribution function.

关键词： Space-time coherent distribution DOA Relative time delay Minimum eigenvalue.

Asymptotics of the Solution to a Stationary Piecewise-Smooth Reaction-Diffusion-Advection Equation

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Chinese Annals of Mathematics,Series B 2023年第1期44卷 81-98页

作者： qian yang Mingkang NI College of Science University of Shanghai for Science and TechnologyShanghai 200093China School of Mathematical Sciences East China Normal UniversityShanghai 200062China Shanghai Key Laboratory of Pure Mathematics and Mathematical Practice Shanghai 200241China

A singularly perturbed boundary value problem for a piecewise-smooth nonlinear stationary equation of reaction-diffusion-advection type is studied.A new class of problems in the case when the discontinuous curve which separates the domain is monotone with respect to the time variable is *** existence of a smooth solution with an internal layer appearing in the neighborhood of some point on the discontinuous curve is *** efficient algorithm for constructing the point itself and an asymptotic representation of arbitrary-order accuracy to the solution is *** sufficiently small parameter values,the existence theorem is proved by the technique of matching asymptotic *** example is given to show the effectiveness of their method.

关键词： Reaction-Diffusion-Advection equation Internal layer Asymptotic method Piecewise-Smooth dynamical system

Correlation between synaptic plasticity, associated proteins, and rehabilitation training in a rat model of cerebral infarction

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Neural Regeneration Research 2008年第6期3卷 670-673页

作者： Dan yang qian Yu Department of Rehabilitation Medicine Affiliated Hospital of Luzhou Medical College Luzhou 646000 Sichuan Province China

All motions provide sensory, motoric, and reflexive input to the central nervous system, as well as playing an important role in cerebral functional plasticity and compensation. Cerebral plasticity has become the theoretical basis of neurorehabilitation. Studies of cerebrovascular disease, in particular, demonstrate that regeneration is accompanied by multiple forms of plasticity, such as functional and structural, in different phases of stroke rehabilitation. This study was designed to measure synaptic plasticity and expression of associated proteins to analyze the effect of rehabilitation training on learning and memory in a rat model of cerebral infarction. Results suggest that rehabilitation training increases expression of nerve growth factor associated protein 43, brain-derived neurotrophic factor, and neural cell adhesion molecules, and also promotes cerebral functional plasticity.

关键词： cerebral infarction rehabilitation training synaptic plasticity associated protein rats

Sections vs. Cross Sections--A Contrast of the Short Stories of Hardy and Chekhov

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学术界 2013年第3期 261-268页

作者： yang qian Zhejiang Wanli University Ningbo Zhejiang 315100

Anton Chekhov,the Russian writer,wrote many outstanding stories. Thomas Hardy,a contemporary English w riter w ith C hekhov,also created many high-quality and ar-tistically valuable short stories. At present,there is broad consensus among researchers and scholars almost around the w orld on the w orth of C hekhov's w orks,but pitifully,the value of Hardy's is somew hat neglected. Therefore,this paper is to draw from the angle of short story creation the outline of the differences betw een these tw o great masters'w orks and highlight the value of Hardy's by making a contrast of the tw o w riters in material selection,theme ex- ploration,characterization,narrative art and contribution to the development of short story.

关键词：英语学习阅读知识阅读材料英语翻译

Impact of the Shrinkage of Arctic Sea Ice on Eurasian Snow Cover Changes in 1979-2021

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Advances in Atmospheric Sciences 2023年第12期40卷 2183-2194,I0007,I0008页

作者： qian yang Shichang KANG Haipeng YU Yaoxian yang State Key Laboratory of Cryospheric Science Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China University of Chinese Academy of Sciences Beijing 100049China Key Laboratory of Land Surface Process and Climate Change in Cold and Arid Regions Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China

Recent research has shown that snow cover induces extreme wintertime cooling and has detrimental *** the dramatic loss of Arctic sea ice certainly has contributed to a more extreme climate,the mechanism connecting sea-ice loss to extensive snow cover is still up for *** this study,a significant relationship between sea ice concentration(SIC)in the Barents-Kara(B-K)seas in November and snow cover extent over Eurasia in winter(November-January)has been found based in observational datasets and through numerical *** reduction in B-K sea ice gives rise to a negative phase of Arctic Oscillation(AO),a deepened East Asia trough,and a shallow trough over *** circulation anomalies lead to colder-than-normal Eurasian mid-latitude temperatures,providing favorable conditions for *** addition,two prominent cyclonic anomalies near Europe and Lake Baikal affect moisture transport and its divergence,which results in increased precipitation due to moisture advection and wind ***,anomalous E-P flux shows that amplified upward propagating waves associated with the low SIC could contribute to the weakening of the polar vortex and southward breakouts of cold *** work may be helpful for further understanding and predicting the snowfall conditions in the middle latitudes.

关键词： Arctic Barents-Kara seas sea ice snow cover Eurasia

PHOTO-INDUCED GRAFT POLYMERIZATION OF ACRYLAMIDE ON POLYPROPYLENE MEMBRANE SURFACE IN THE PRESENCE OF DIBENZYL TRITHIOCARBONATE

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Chinese Journal of Polymer Science 2007年第2期25卷 221-226页

作者： qian yang Jing Tian Zhi-kang Xu Institute of Polymer Science and Key Laboratory of Macromolecule Synthesis and Functionalization （Ministry of Education） Zhejiang University Hangzhou 310027 China

Ultraviolet （UV）-induced graft polymerization of acrylamide （AAm） on polypropylene substrates was successfully conducted using dibenzyl trithiocarbonate （DBTTC） as photoinitiator. It was confirmed by chemical analysis and surface morphology observation with attenuated total reflectance Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy. A possible mechanism for this graft process was presented, which suggested that, under UV irradiation, the C： S bond in DBTTC could split and abstract a hydrogen from the polypropylene surface and a surface free radical was then formed, and initiated the graft polymerization of AAm.

关键词： Graft polymerization Surface modification Acrylamide Trithiocarbonate UV.

A Fast Calculation Method for Long-term Security-constrained Unit Commitment of Large-scale Power Systems with Renewable Energy

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Journal of Modern Power Systems and Clean Energy 2022年第5期10卷 1127-1137页

作者： qian yang Jianxue Wang Hongrui Yin Qingtao Li School of Electrical Engineering Xi'an Jiaotong UniversityXi'anChina

With the increase in the penetration rate of renewable energy, the planning and operation of power systems will face huge challenges. To ensure the sufficient utilization of renewable energy, the reasonable arrangement for the long-term power generation plan has become more crucial. Security-constrained unit commitment(SCUC) is a critical technical means to optimize the long-term power generation plan. However, the plentiful power sources and the complex grid structure in largescale power systems will bring great difficulties to long-term SCUC. In this paper, we propose a fast calculation method for long-term SCUC of large-scale power systems with renewable energy. First, a method for unit status reduction based on temporal decomposition is proposed, which will reduce plenty of binary variables and intertemporal constraints in SCUC. Then,an efficient redundant constraint identification(RCI) method is developed to reduce the number of network constraints. Furthermore, a joint accelerated calculation framework for status reduction and RCI is formed, which can reduce the complexity of long-term SCUC while ensuring a high-precision feasible solution. In case studies, numerical results based on two test systems ROTS2017 and NREL-118 are analyzed, which verify the effectiveness and scalability of the proposed calculation method.

关键词： Accelerated calculation framework long-term security-constrained unit commitment(SCUC) redundant constraints identification renewable energy unit status reduction