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RATIONAL SPECTRAL COLLOCATION METHOD FOR A COUPLED SYSTEM OF SINGULARLY PERTURBED BOUNDARY VALUE PROBLEMS

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Journal of Computational Mathematics 2011年第4期29卷 458-473页

作者： Suqin Chen Yingwei Wang Xionghua wu Department of Mathematics Tongji University Shanghai 200092 China

A, novel collocation method for a coupled system of singularly perturbed linear equations is presented. This method is based on rational spectral collocation method in barycentric form with sinh transform. By sinh transform, the original Chebyshev points are mapped into the transformed ones clustered near the singular points of the solution. The results from asymptotic analysis about the singularity solution are employed to determine the parameters in this sinh transform. Numerical experiments are carried out to demonstrate the high accuracy and efficiency of our method.

关键词： Singular perturbation Coupled system Rational spectral collocation method,Boundary layer Reaction-diffusion Convection-diffusion.

Complicated target recognition by archaeal box C/D guide RNAs

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Science China(Life Sciences) 2024年第4期67卷 631-644页

作者： Jiayin Wang Songlin wu Keqiong Ye Key Laboratory of RNA Science and Engineering CAS Center for Excellence in BiomacromoleculesInstitute of BiophysicsChinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China

Box C/D RNAs guide the site-specific formation of 2′-O-methylated nucleotides(Nm)of RNAs in eukaryotes and *** C/D RNAs have been profiled in several archaea,their targets have not been experimentally ***,we mapped Nm in r RNAs,t RNAs,and abundant small RNAs(s RNAs)and profiled C/D RNAs in the crenarchaeon Sulfolobus *** targets of C/D RNAs were assigned by analysis of base-pairing interactions,in vitro modification assays,and gene deletion experiments,revealing a complicated landscape of C/D RNA-target interactions.C/D RNAs widely use dual antisense elements to target adjacent sites in r RNAs,enhancing modification at weakly bound *** consecutive sites can be guided with the same antisense element upstream of box D or D′,a phenomenon known as doublespecificity that is exclusive to internal box D′in eukaryotic C/D *** C/D RNAs guide modification at a single non-canonical *** study reveals the global landscape of RNA-guided 2′-O-methylation in an archaeon and unexpected targeting rules employed by C/D RNA.

关键词： C/D RNA 2′-O-methylation archaea guide RNA RNA modification

Improvement of tree-like network constructal method for heat conduction optimization

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Science China(Technological Sciences) 2006年第3期49卷 332-341页

作者： wu Wenjun CHEN Lingen SUN Fengrui Postgraduate School Naval University of Engineering Wuhan 430033 China Postgraduate School Naval University of Engineering Wuhan 430033 China Postgraduate School Naval University of Engineering Wuhan 430033 China

The analysis of the “tree-like network” construct method has been repeated. The high effective conduction channel distribution has been optimized again, without the premise that the new order assembly construct must be assembled by the optimized last order construct. It is proved that the “tree-like network” construct method is faultiness. A more optimal construct is obtained,; when the thermal conductivity; the proportion of the two heat conduction materials are constant, the limit of the minimum heat resistance is derived. All these conclusions can be used to guide the engineering application.

关键词： constructal theory, 'tree-like network' construct method, high effective conduction channel distribution, generalized thermodynamic optimization.

DEM study on effect of particle roundness on biaxial shearing of sand

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Underground Space 2021年第6期6卷 678-694页

作者： Mengmeng wu Linghong Xiong Jianfeng Wang Department of Architecture and Civil Engineering City University of Hong KongHong KongChina Shenzhen Research Institute of City University of Hong Kong ShenzhenChina

In this study,discrete element method(DEM)simulations of a biaxial test were used to examine the effect of particle roundness on the mechanical behavior of sands at both the macro and micro ***,a stack of microcomputed tomography images were binarized,segmented,and labeled using advanced image processing and analysis ***,a spherical harmonic(SH)analysis,which involves a complete set of orthogonal functions,was implemented to rebuild the natural particle ***,five templates of virtual particles were built in a DEM simulation,four of which were obtained from SH degrees of 3,8,12,and 15,and one template was an elementary sphere.A flexible membrane was numerically generated to allow the material to deform freely under a prescribed confining ***,the effect of particle roundness on the mechanical properties of granular materials was investigated and *** shear bands were found to intersect,forming an X shape in both the rotation and displacement ***,a lower particle roundness results in higher deviatoric stress and stronger dilation in the volumetric change.A decrease in particle roundness leads to less rotation of particles despite a higher displacement *** addition,a larger SH degree leads to smaller normalized contact forces of the *** implies that decreasing the roundness results in higher anisotropy of the contact forces.

关键词： Grain shape Roundness Flexible membrane Spherical harmonic analysis Discrete element method

Observer design for matrix second order linear systems with uncertain disturbance input-a parametric approach

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Journal of Systems Engineering and Electronics 2006年第4期17卷 811-816,823页

作者： wu Yunli Li Zhibin Duan Cruangren National Laboratory of Space Intelligent Control Technology Beijing Inst. of Control Engineering Beijing 100080P.R.China Centre of Control Theory and Guidance Technology Harbin Inst. of Technology Harbin 150001P.R.China

A simple parametric approach to design a full-order observer for matrix second-order linear systems with uncertain disturbance input in the matrixsecond-order framework is proposed. The basic idea is to minimize the H2 norm of the transfer function from disturbance to estimation error using the design degrees of freedom provided by a parametric approach in the observer design. Besides the design parameters, the eigenvalues of the closed-loop system are also optimized within desired regions on the left-half of the complex plane. Using the proposed approach, additional specifications can be easily achieved. A spring-mass system is using to show the effect of the proposed approaches.

关键词： linear systems uncertain disturbance input observers parametric approach optimization.

An improved ARTSIST sea ice algorithm based on 19 GHz modified 91 GHz

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Acta Oceanologica Sinica 2019年第10期38卷 93-99页

作者： Zhankai wu Xingdong Wang Xuemei Wang College of Information Science and Engineering Henan University of TechnologyZhengzhou 450001China Institute of Remote Sensing and Digital Earth Chinese Academy of SciencesBeijing 100094China

An enhanced ARTSIST Sea Ice(ASI)algorithm is presented based on a data fusion method of calculating total sea ice concentration from high-frequency microwave *** that use low-frequency data to calculate total sea ice concentration are less affected by atmosphere,but their spatial resolutions tend to be *** contrast,algorithms using high-frequency data have higher spatial resolution but are significantly influenced by *** errors can be eliminated using weather filters,the concentration of mixed pixels cannot be ***,an enhanced ASI algorithm uses the 19 GHz polarization difference to modify the 91 GHz polarization difference,which is substituted into the ASI algorithm to calculate total sea ice *** total sea ice concentration results are obtained based on Special Sensor Microwave Imager Sounder(SSMIS)data on January 3,from 2008 to *** sea ice area and average concentration using the enhanced ASI algorithm are compared to traditional ASI and NASA Team *** the Marginal Ice Zone,there is a considerable difference between the enhanced and traditional ASI algorithm results,with the former much closer to the NASA Team *** proposed algorithm effectively modifies the concentration of the mixed pixels in the marginal zone.

关键词： ASI algorithm sea ice concentration SSMIS NASA Team algorithm

High-Resolution Modeling Study of the Kuroshio Path Variations South of Japan

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Advances in Atmospheric Sciences 2014年第5期31卷 1233-1244页

作者： LI Rui ZHANG Zuowei wu Lixin Physical Oceanography Laboratory/Qingdao Collaborative Innovation Center of Marine Science and Technology Ocean University of China

A high-resolution ocean general circulation model （OGCM） is used to investigate the Kuroshio path variations south of Japan. The model reproduces many important features of the Kuroshio system including its interannual bimodal variability south of Japan. A decreasing trend of the spatial averaged relative vorticity is detected when the Kuroshio takes the non-large meander （NLM） path, and during the transition period from the NLM to the large meander （LM）, a sudden release of velocity shear corresponds well to the weakening of the Shikoku recirculation gyre （SRG）, which plays a key role in modulating the Kuroshio path variations. Analysis of eddy energetics indicates that baroclinic instability is mainly responsible for the formation of the LM. In addition, further analysis shows that the strength of the SRG could be largely influenced by the baroclinic Rossby wave adjustment process, forced by the wind stress curl anomalies in the North Pacific basin, based on the model investigation. It is suggested that the cyclonic disturbances might account for the weakening of the SRG, and act as a remote trigger for the baroclinic instability of the Kuroshio south of Japan.

关键词： OGCM Kuroshio path variations large meander Rossby wave

A naive optimization method for multi-line systems with alternative machines

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Frontiers of Mechanical Engineering 2019年第4期14卷 377-392页

作者： Weichang KONG Fei QIAO Qidi wu School of Electronics and Information Engineering Tongji UniversityShanghai 201804China

The scheduling of parallel machines and the optimization of multi-line systems are two hotspots in the field of complex manufacturing *** the two problems are considered simultaneously,the resulting problem is much more complex than either of *** sufficient training data for conventional data-based optimization approaches is difficult because of the high diversity of system ***,optimization of multi-line systems with alternative machines requires a simple mechanism and must be minimally dependent on historical *** define a general multi-line system with alternative machines,this study introduces the capability vector and matrix and the distribution vector and matrix.A naive optimization method is proposed in accordance with classic feedback control theory,and its key approaches are *** a reasonable target value is provided,the proposed method can realize closed-loop optimization to the selected objective *** studies are performed on a real 5/6-inch semiconductor wafer manufacturing facility and a simulated multi-line system constructed on the basis of the MiniFAB *** show that the proposed method can effectively and efficiently optimize various objective *** method demonstrates a potential for utilization in multi-objective optimization.

关键词： multi-line systems alternative machines feedback control closed-loop optimization

Land-use changes in the small watershed of the Loess Plateau,hilly-gully region, China

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Journal of Forestry Research 2015年第1期26卷 91-99页

作者： Yini Han Jianzhi Niu Feizhou wu Key Laboratory of Soil and Water Conservation & Desertification Combating Beijing Forestry University

As more and more farmland is converted to forestry, the need for effective decision support regarding the use of land in the fragile ecological environment of the Loess Plateau hilly-gully area. The Luoyugou watershed was chosen as the study area to calculate the single dynamic degree, integrated dynamic degree, and change indexes of land use, as well as the land-use type transition matrix. This was done by interpreting the TM and SPOT images of the Luoyugou watershed in 1986, 1995, and2004 and making statistical analysis. The results of ou statistical analysis show that the conversion of slope farm land to terrace and forest land plays a dominant role in land-use changes in the Luoyugou watershed from 1986 to2004. The land-use changes are mainly driven by popula tion growth, socio-economic development, consume spending, and investment in forest ecology.

关键词： Loess Plateau hilly-gully region Luoyugou watershed Land use and cover changes Driving force