检索结果-南通市图书馆

Double-temperature ratchet model and current reversal of coupled Brownian motors

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers of physics 2017年第6期12卷 43-52页

作者： Chen-pu Li Hong-Bin Chen Zhi-Gang zheng Department of Physics Beijing Normal University Beijing 100875 China College of Science Hebei University of ArchitectureZhangjiakou 075000 China Institute of Systems Science (ISS) Huaqiao University Xiamen 361021 China College of Information Science and Engineering Huaqiao University Xiamen 361021 China

On the basis of the transport features and experimental phenomena observed in studies of molecular motors, we propose a double-temperature ratchet model of coupled motors to reveal tile dynamical mechanism of cooperative transport of motors with two heads, where the interactions and asynchrony between two motor heads are taken into account. We investigate the collective unidirectional trans- port of coupled system and find that the direction of motion can be reversed under certain conditions. Reverse motion can be achieved by modulating the coupling strength, coupling free length, and asym- metric coefficient of the periodic potential, which is understood in terms of the effective potential theory. The dependence of the directed current on various parameters is studied systematically. Di- rected transport of coupled Brownian motors can be manipulated and optimized by adjusting the pulsation period or the phase shift of the pulsation temperature.

关键词： coupled Brownian motors ratchet model effective potential noise

Investigation of feasibility of alkali-cosolvent flooding in heavy oil reservoirs

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Petroleum Science 2023年第3期20卷 1608-1619页

作者： Yi-Bo Li He-Fei Jia Wan-fen pu Bing Wei Shuo-Shi Wang Na Yuan State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Southwest Petroleum UniversityChengdu610500SichuanChina Mewbourne School of Petroleum and Geological Engineering University of OklahomaNormanOK73019USA

Cold production is a challenge in the case of heavy oil because of its high viscosity and poor fluidity in reservoir ***-cosolvent-polymer flooding is a type of microemulsion flooding with low costs and possible potential for heavy oil ***,the addition of polymer may cause problems with injection in the case of highly viscous ***,in this study the feasibility of alkali-cosolvent(AC)flooding in heavy oil reservoirs was investigated via several groups of *** interfacial tension between various AC formulations and heavy crude oil was measured to select appropriate *** behavior tests were performed to determine the most appropriate formulation and conditions for the generation of a *** flooding experiments were carried out to investigate the displacement efficiency of the selected Ac *** results showed that the interfacial tension between an AC formulation and heavy oil could be reduced to below 1o-3 mN/m but differed greatly between different types of cosolvent.A butanol random polyether series displayed good performance in reducing the water-oil interfacial tension,which made it possible to form a Type Il microemulsion in reservoir *** to the results of the phase behavior tests,the optimal salinity for different formulations with four cosolvent concentrations(0.5 wt%,1 wt%,2 wt%,and 3 wt%)was 4000,8000,14000,and 20000 ppm,*** results of rheological measurements showed that Type Ill microemulsion had a viscosity that was ten times that of *** results of sandpack flooding experiments showed that,in comparison with waterflooding,the injection of a certain Ac formulation slug could reduce the injection *** pressure gradient during waterflooding and AC flooding was around 870 and 30-57 kPa/m,*** the addition of an AC slug,the displacement efficiency was 30%-50%higher than in the case of waterflooding.

关键词： Heavy oil Microemulsion Cold production Chemical flooding Displacement efficiency

Ratchet motion and current motors in pulsating reversal of coupled Brownian symmetric potentials

在线全文

学校读者我要写书评

暂无评论

Frontiers of physics 2017年第4期12卷 197-206页

作者： Chen-pu Li Hong-Bin Chen Zhi-Gang zheng Department of Physics Beijing Normal University Beijing 100875 China College of Science Hebei University of Architecture Zhangjiakou 075000 China Institute of Systems Science (ISS) Huaqiao University Xiamen 361021 China College of Information Science and Engineering Huaqiao University Xiamen 361021 China

In this study, we investigate the collective directed transport of coupled Brownian particles in spatially symmetric periodic potentials under time-periodic pulsating modulations. We find that the coupling between two particles can induce symmetry breaking and consequently collective directed motion. Moreover, the direction of motion can be reversed under certain conditions. The dependence of directed current on various parameters is systematically studied, reverse motion can be achieved by modulating the coupling free length and the phase shift of tile pulsating potential. The dynamical mechanism of these transport properties is understood in terms of the effective-potential theory and the space-time transformation invariance. The directed transport of coupled Brownian motors can be maniplflated and optimized by adjusting the coupling strength, pulsating frequency, or noise intensity.

关键词： coupled Brownian motors ratchet effective potential symmetric periodic potential noise

Density Functional Studies on Isonicotinato Lead(II) Complex [Pb(C_5H_4NCOO)_2]

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 Structural Chemistry 2006年第6期25卷 657-662页

作者： ZHAO pu-Su JIAN Fang-Fang LI Chun-Lei zheng Jian Department of Chemistry Huaiyin Teachers＇College Huaian Jiangsu 223001 China New Materials ＆ Function Coordination Chemistry Laboratory Qingdao University of Science and Technology Qingdao Shandong 266042 China

The title compound of isonicotinato lead（Ⅱ） [Pb（C5H4NCOO）2] has been optimized at B3LYP/LANL2DZ level of theory and calculated results show that the lead（Ⅱ） ion adopts 4-coordinate geometry. Atomic charge distributions indicate that during forming the title compound, each isonicotinic acid ion transfers -0.452 e to lead（Ⅱ） ion. The electronic spectra calculations show that there exist two absorption bands and the electronic transitions are mainly derived from the contribution of intraligand π→π^＊ transition and ligand-to-metal charge transfer （LMCT） transition. The thermodynamic properties of the title compound at different temperatures have been calculated and corresponding relations between property and temperature have also been obtained. The calculation of the second order optical nonlinearity was carried out, and the molecular hyperpolarizability was 3.62365^＊10^-30 esu.

关键词： isonicotinato lead(Ⅱ) complex density functional theory electronic spectra thermal property analysis the second order optical nonlinearity

Control of vertical phase separation in high performance non-fullerene organic solar cell by introducing oscillating stratification preprocessing

在线全文

学校读者我要写书评

暂无评论

Nano Research 2021年第5期14卷 1319-1325页

作者： Dayong Zhang pu Fan Jinyu Shi Yifan zheng Jian Zhong Junsheng Yu State Key Laboratory of Electronic Thin Films and Integrated Devices School of Optoelectronic Science and EngineeringUniversity of Electronic Science and Technology of ChinaChengdu610054China Shanghai Institute of Optics and Fine Mechanics Chinese Academy of SciencesShanghai201800China

Non-fullerene organic solar cell(NFOSC)has attracted tremendous attention due to their great potential for commercial *** improve its power conversion efficiency(PCE),generally,sequential solution deposition(SSD)methods have been employed to construct the graded vertical phase separation(VPS)of the bulk-heterojunction(BHJ)active layer for efficient exciton separation and charge ***,a variety of orthogonal solvents used in the SSD may lead to the unpredicted change in the BHJ morphology and introduce additional defects inside the BHJ bulk thus complicate the fabrication ***,a simple oscillating stratification preprocessing(OSP)is developed to facilitate the formation of graded VPS among the BHJ *** a result,a significant improvement is obtained in PCE from 10.96%to 12.03%,which is the highest value reported among PBDB-T:ITIC based NFOSC.

关键词： oscillating stratification preprocessing graded vertical phase separation non-fullerene organic solar cells high performance sequential solution deposition

Numerical Solution of Steady-State Free Boundary Problems using the Singular Boundary Method

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Advances in Applied Mathematics and Mechanics 2021年第1期13卷 163-175页

作者： fen Chen Bin zheng Ji Lin Wen Chen College of Civil Engineering Hefei University of TechnologyHefeiAnhui 230009China College of Civil Engineering Taizhou UniversityTaizhouZhejiang 318000China College of Mechanics and Materials Hohai UniversityNanjingJiangsu 211100China

In this paper,the recently-developed singular boundary method is applied to address free boundary *** mesh-less numerical method is based on the use of the origin intensity factors with fundamental *** numerical examples and their results are compared with the results obtained using traditional *** comparisons indicate that the proposed scheme yields good results in determining the position of the free boundary.

关键词： Seepage flow singular boundary method mesh-less origin intensity factors

Capsizing Probability of Dead Ship Stability in Beam Wind and Wave for Damaged Ship

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

China Ocean Engineering 2019年第2期33卷 245-251页

作者： HU Li-fen ZHANG Ke-zheng LI Xiao-ying CHANG Run-xin School of Transporation Ludong University

The International Maritime Organization has developed the second-generation intact stability criteria. Thus, damage stability criteria can be established in the future. In order to identity the capsizing probability of damaged ship under dead ship condition, this paper investigates two methods that can be used to research the capsizing probability in time domain, which mainly focus on the nonlinear righting lever GZ curve solution. One method subjects the influence of damaged tanks on the hull shape down to the wind and wave, and the other method is consistent with the real-time calculation of the GZ curve. On the basis of one degree of freedom rolling equation, the solution is Monte Carlo method, and a damaged fishery bureau vessel is taken as a sample ship. In addition, the results of the time-domain capsizing probability under different loading conditions are compared and analyzed. The relation of GM and heeling angle with the capsizing probability is investigated, and its possible reason is analyzed. On the basis of combining the time-domain flooding process with the capsizing probability calculation, this research aims to lay the foundation for the study of capsizing probability in time domain under dead ship condition, as well as provide technical support for capsizing mechanism of dead ship stability and damage stability criteria establishment in waves.

关键词： damage stability criteria dead ship stability capsizing probability flooding process time domain

Downward current electron beams observed at the dipolarization front

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2013年第8期58卷 913-919页

作者： zheng Hao FU SuiYan ZONG QuiGang pu ZuYin School of Earth and Space Sciences Peking University

The strong field-aligned pitch angle distribution of electrons is observed right at the dipolarization front (DF) before the arriving of a high speed flow when the four Cluster satellites are traveling in the magnetotail around 15 R E on July 22, 2001. The increased electron fluxes only last for a short time period at the DF, corresponding to just a few bouncing periods for 1 keV electrons. The field-aligned current contributed by these electrons agrees well with that calculated by the magnetic field observations by four satellites at the front. These electron streams are found in the energy range of 0.2-2 keV, peak around 1 keV. It is suggested that these downward current electrons may be originated near the aurora region by some kinds of potential structure. The occurrence of these electrons implies that the formation of the dipolarization front and the associated field-aligned current play an important role in the magnetosphere-ionosphere coupling.

关键词：场向电流电子束极化 Cluster 电离层耦合磁场观测能量范围高速流

Bridge Crack Segmentation Method Based on Parallel Attention Mechanism and Multi-Scale Features Fusion

在线全文

学校读者我要写书评

暂无评论

Computers, Materials & Continua 2023年第3期74卷 6485-6503页

作者： Jianwei Yuan Xinli Song Huaijian pu Zhixiong zheng Ziyang Niu College of Civil Engineering Changsha University of Science and TechnologyChangsha410114China College of Computer&Communication Engineering Changsha University of Science and TechnologyChangsha410114China China Construction Fifth Engineering Bureau Co. Ltd.Changsha410004China

Regular inspection of bridge cracks is crucial to bridge maintenance and *** traditional manual crack detection methods are timeconsuming,dangerous and *** the same time,for the existing mainstream vision-based automatic crack detection algorithms,it is challenging to detect fine cracks and balance the detection accuracy and ***,this paper proposes a new bridge crack segmentationmethod based on parallel attention mechanism and multi-scale features fusion on top of the DeeplabV3+network ***,the improved lightweight MobileNetv2 network and dilated separable convolution are integrated into the original DeeplabV3+network to improve the original backbone network Xception and atrous spatial pyramid pooling(ASPP)module,respectively,dramatically reducing the number of parameters in the network and accelerates the training and prediction speed of the ***,we introduce the parallel attention mechanism into the encoding and decoding *** attention to the crack regions can be enhanced from the aspects of both channel and spatial parts and significantly suppress the interference of various ***,we further improve the detection performance of the model for fine cracks by introducing a multi-scale features fusion *** research results are validated on the self-made *** experiments show that our method is more accurate than other *** intersection of union(IoU)and F1-score(F1)are increased to 77.96%and 87.57%,*** addition,the number of parameters is only 4.10M,which is much smaller than the original network;also,the frames per second(FPS)is increased to 15 frames/*** results prove that the proposed method fits well the requirements of rapid and accurate detection of bridge cracks and is superior to other methods.

关键词： Crack detection DeeplabV3+ parallel attention mechanism feature fusion