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Relaxation Property and Stability Analysis of the Quasispecies Models

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Communications in Theoretical Physics 2009年第10期52卷 726-734页

作者： FEGN xiao-Li LI Yu-xiao gu Jian-Zhong ZHUO Yi-Zhong School of Physical Engineering Zhengzhou University Zhengzhou 450052 China Center for Computational and System Biology Institute of Biophysics Chinese Academy of Science Beijing 100101 China China Institute of Atomic Energy P.O. Box 275（18） Beijing 102413 China Center of Theoretical Nuclear Physics National Laboratory of Heavy Ion Accelerator of Lanzhou Lanzhou 730000 China

The relaxation property of both Eigen model and Crow-Kimura model with a single peak fitness landscape is studied from phase transition point of view. We first analyze the eigenvalue spectra of the replication mutation matrices. For sufficiently long sequences, the almost crossing point between the largest and seeond-largest eigenvalues locates the error threshold at which critical slowing down behavior appears. We calculate the critical exponent in the limit of infinite sequence lengths and compare it with the result from numerical curve fittings at sufficiently long sequences. We find that for both models the relaxation time diverges with exponent 1 at the error （mutation） threshold point. Results obtained from both methods agree quite well. From the unlimited correlation length feature, the first order phase transition is further confirmed. Finally with linear stability theory, we show that the two model systems are stable for all ranges of mutation rate. The Igigen model is asymptotically stable in terms of mutant classes, and the Crow-Kimura model is completely stable.

关键词： relaxation time critical exponent error threshold

Location monitoring approach of underground pipelines using time-sequential images

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Underground Space 2024年第2期15卷 59-75页

作者： Haoruo Xu Lei he Yuyang Chu Junchen he Huaiguang xiao Chengmeng Shao School of Civil Engineering Southeast UniversityNanjing 210096JiangsuChina The 3rd branch China Railway 16th Bureau Group Co.LTDHuzhou 313000ZhejiangChina

The location monitoring of underground pipelines is of utmost significance as it helps the effective management and maintenance of the pipelines,and facilitates the planning of nearby projects,preventing damage to the ***,currently there is a serious lack of data on the locations of underground *** paper proposes an image-based approach for monitoring the locations of underground pipelines by combing deep learning and visual-based *** proposed approach can build the monitoring model for underground pipelines and characterize their locations through their centroid *** advantages are:(1)simplicity:it only requires time-sequential images of the inner walls of underground pipelines;(2)clarity:the location model and the location curve of underground pipelines can be provided quickly;(3)robustness:it can cope with some existing problems in underground pipelines,such as light variations and small viewing angles.A lightweight approach for monitoring the locations of underground pipelines is *** proposed approach’s effectiveness has been validated through laboratory simulation experiments,demonstrating accuracy at the millimeter level.

关键词： Underground pipelines Location monitoring Time-sequential images Visual-based reconstruction Deep learning

S-curvature of Doubly Warped Product of Finsler Manifolds

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维普期刊数据库

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Acta Mathematica Sinica,English Series 2020年第11期36卷 1292-1298页

作者： Zhao YANG Yong he xiao Ling ZHANG College of Mathematics and Systems Science Xinmjiang UniversityUrumqi 830046P.R.China Department of Mathematics Xinjiang Normal UnitersityUrumqi 830017P.R.China College of Mathematics and Systems Science Xinjiang UniversityUrumqi 830046P.R.China

Doubly warped product of Finsler manifolds is useful in theoretical physics,particularly in general *** this paper,we study doubly warped product of Finsler manifolds with isotropic mean Berwald curvature or weak isot... 详细信息

关键词： Doubly warped product of Finsler manifold weak isotropic S-curvature isotropic mean Berwald curvature weakly Berwald manifolds

Assessing the effects of vegetation and precipitation on soil erosion in the Three-River headwaters Region of the Qinghai-Tibet Plateau,China

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Journal of Arid Land 2020年第5期12卷 865-886页

作者： he Qian DAI xiao'ai CheN Shiqi College of Earth Science Chengdu University of TechnologyChengdu 610059China College of Foreign Languages and Cultures Chengdu University of TechnologyChengdu 610059China

Soil erosion in the Three-River headwaters Region(TRHR)of the Qinghai-Tibet Plateau in China has a significant impact on local economic development and ecological *** and precipitation are considered to be the main factors for the variation in soil ***,it is a big challenge to analyze the impacts of precipitation and vegetation respectively as well as their combined effects on soil erosion from the pixel *** assess the influences of vegetation and precipitation on the variation of soil erosion from 2005 to 2015,we employed the Revised Universal Soil Loss Equation(RUSLE)model to evaluate soil erosion in the TRHR,and then developed a method using the Logarithmic Mean Divisia Index model(LMDI)which can exponentially decompose the influencing factors,to calculate the contribution values of the vegetation cover factor(C factor)and the rainfall erosivity factor(R factor)to the variation of soil erosion from the pixel *** general,soil erosion in the TRHR was alleviated from 2005 to 2015,of which about 54.95%of the area where soil erosion decreased was caused by the combined effects of the C factor and the R factor,and 41.31%was caused by the change in the R *** were relatively few areas with increased soil erosion modulus,of which 64.10%of the area where soil erosion increased was caused by the change in the C factor,and 23.88%was caused by the combined effects of the C factor and the R ***,the combined effects of the C factor and the R factor were regarded as the main driving force for the decrease of soil erosion,while the C factor was the dominant factor for the increase of soil *** area with decreased soil erosion caused by the C factor(12.10×10^3 km^2)was larger than the area with increased soil erosion caused by the C factor(8.30×10^3 km^2),which indicated that vegetation had a positive effect on soil *** study generally put forward a new method for quantitative assessment of the impacts

关键词： soil erosion vegetation cover rainfall erosivity Logarithmic Mean Divisia Index quantitative assessment Three-River headwaters Region

Underlying principle of efficient propulsion in flexible plunging foils

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Acta Mechanica Sinica 2014年第6期30卷 839-845页

作者： xiao-Jue Zhu guo-Wei he Xing Zhang LNM Institute of MechanicsChinese Academy of Sciences

Passive flexibility was found to enhance propulsive efficiency in swimming *** this study,we numerically investigate the roles of structural resonance and hydrodynamic wake resonance in optimizing efficiency of a flexible plunging *** results indicates that（1）optimal efficiency is not necessarily achieved when the driving frequency matches the structural eigenfrequency;（2）optimal efficiency always occurs when the driving frequency matches the wake resonant frequency of the time averaged velocity ***,the underlying principle of efficient propulsion in flexible plunging foil is the hydrodynamic wake resonance,rather than the structural *** addition,we also found that whether the efficiency can be optimized at the structural resonant point depends on the strength of the leading edge vortex relative to that of the trailing edge *** result of this work provides new insights into the role of passive flexibility in flapping-based propulsion.

关键词： Flexibility Propulsive efficiency Structural resonance Hydrodynamic wake resonance

Effect of CO_2 partial pressure on SCC behavior of welded X80 pipeline in simulated soil solution

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Acta Metallurgica Sinica(English Letters) 2011年第1期24卷 65-74页

作者： Ming WU Xu CheN Chuan he Jun xiao College of Petroleum Engineering Liaoning Shihua University Eushun 113001 China

The stress corrosion cracking （SCC） behavior of welded X80 pipeline steel in simulated Ku＇erle soil solution was studied by means of electrochemical impedance spectroscopy （EIS） and slow strain rate tests （SSRT）. The microstructure of the welded steel was observed by optical microscopy （OM）. It is demonstrated that the microstructure of the weld metal consists of acicular ferrite and grain boundary ferrite, while that of heat affected zone （HAZ） is a mixture of acicular ferrite and bainitic ferrite micro- constituents. The microstructure of the base steel is composed of ferrite and pearlite. The anodic dissolution of X80 pipeline steel in simulated Ku＇erle soil solution could be enhanced and the SCC sensitivity increased with the increase of CO2 partial pressure. The SCC mechanism of X80 pipeline is a mixing mechanism of hydrogen embrittlement combined with anodic dissolution, and the hydrogen embrittlement plays a leading role. The higher SCC sensitivity of the weld metal was attributed to the metallurgical transformation, local hardening and residual stress.

关键词： X80 steel Weld metal CO2 partial pressure SCC

Development and application of a water pollution emergency response system for the Three Gorges Reservoir in the Yangtze River, China

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Journal of Environmental Sciences 2011年第4期23卷 595-600页

作者： Qiang he Shujuan Peng Jun Zhai Haiwen xiao Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment Ministry of Education Chongqing University Chongqing 400045 China.

There are many watercraft and production accidents in the Three Gorges Reservoir Area （TGRA） of the Yangtze River in China every year. Accidents threaten the water quality of the 1085 km 2 surface area of the TGRA and millions of local people if oil and chemical leakage were to occur. A water pollution management system for emergency response （WPMS ER） was therefore designed for the management of pollution in this area. An integrated geographic information system （GIS）-based water pollution management information system for the TGRA, called WPMS ER TGRA, was developed in this study. ArcGIS engine was used as the system development platform, and Visual Basic as the programming language. The models for hydraulic and water quality simulation and the generation of body-fitted coordinates were developed and programmed as a dynamically linked library file using Visual Basic, and they can be launched by other computer programs. Subsequently, the GIS-based information system was applied to the emergency water pollution management of a shipwreck releasing 10 tons of phenol into the Yangtze River during two hours. The results showed that WPMS ER TGRA can assist with emergency water pollution management and simulate the transfer and diffusion of accidental pollutants in the river. Furthermore, it can quickly identify the affected area and how it will change over time within a few minutes of an accident occurring.

关键词： water pollution emergency emergency response management information system the Three Gorges Reservoir

Interaction between a screw dislocation and a circular nano-inhomogeneity with a bimaterial interface

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Acta Mechanica Solida Sinica 2017年第1期30卷 39-50页

作者： Tengwu he Wanshen xiao Xiangdong Li Yan Zhang College of Mechanical and Vehicle Engineering Hunan University

The problem of a screw dislocation interacting with a circular nano-inhomogeneity near a bimaterial interface is investigated. The stress boundary condition at the interface between the inhomogeneity and the matrix is modified by incorporating surface/interface stress. The analytical solutions to the problem in explicit series are obtained by an efficient complex variable method associated with the conformal mapping function. The image force exerted on the screw dislocation is also derived using the generalized Peach–Koehler formula. The results indicate that the elastic interference of the screw dislocation and the nano-inhomogeneity is strongly affected by a combination of material elastic dissimilarity, the radius of the inclusion, the distance from the center of inclusion to the bimaterial interface, and the surface/interface stress between the inclusion and the matrix. Additionally, it is found that when the inclusion and Material 3 are both harder than the matrix（ μ1 〉 μ2 and μ3 〉 μ2）, a new stable equilibrium position for the screw dislocation in the matrix appears near the bimaterial interface; when the inclusion and Material 3 are both softer than the matrix（ μ1 〈 μ2 and μ3 〈 μ2）, a new unstable equilibrium position exists close to the bimaterial interface.

关键词： Screw dislocation Image force Conformal mapping Bimaterial interface Nano-inhomogeneity

Research on performance optimization of virtual data space across WAN

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Frontiers of Computer Science 2024年第6期18卷 186505页

作者： HUO Jiantong HUO Zhisheng xiao Limin he Zhenxue State Key Laboratory of Software Development Environment Beihang University School of Computer Science and Engineering Beihang University High Performance Computing Center Beihang University hebei Key Laboratory of Agricultural Big Data hebei Agricultural University

For the high-performance computing in a WAN environment, the geographical locations of national supercomputing centers are scattered and the network topology is complex, so it is difficult to form a unified view of resources. To aggregate the widely dispersed storage resources of national supercomputing centers in China, we have previously proposed a global virtual data space named GVDS in the project of “High Performance Computing Virtual Data Space”, a part of the National Key Research and Development Program of China. The GVDS enables large-scale applications of the high-performance computing to run efficiently across WAN. However, the applications running on the GVDS are often data-intensive, requiring large amounts of data from multiple supercomputing centers across WANs. In this regard, the GVDS suffers from performance bottlenecks in data migration and access across WANs. To solve the above-mentioned problem, this paper proposes a performance optimization framework of GVDS including the multitask-oriented data migration method and the request access-aware IO proxy resource allocation strategy. In a WAN environment, the framework proposed in this paper can make an efficient migration decision based on the amount of migrated data and the number of multiple data sources, guaranteeing lower average migration latency when multiple data migration tasks are running in parallel. In addition, it can ensure that the thread resource of the IO proxy node is fairly allocated among different types of requests (the IO proxy is a module of GVDS), so as to improve the application’s performance across WANs. The experimental results show that the framework can effectively reduce the average data access delay of GVDS while improving the performance of the application greatly.

关键词： storage aggregation across WANs large-scale applications GVDS data migration allocation of IO proxy resource