检索结果-南通市图书馆

A new global raster water mask at 250 m resolution

International journal of Digital Earth 2009年第4期2卷 291-308页

作者： m.L.Carroll j.R.Townshend C.m.Dimiceli P.Noojipady R.A.Sohlberg Department of Geography University of MarylandCollege Park MDUSA

Accurate depiction of the land and water is critical for the production of land surface parameters from remote sensing data *** parameters,including the land surface temperature,active fires and surface reflectance,can be processed differently when the underlying surface is water as compared with *** errors in the underlying water mask can then pervade into these products and any products created from *** many global databases have been created to depict global surface *** databases still fall short of the current needs of the terrestrial remote sensing community working at 250 m spatial *** most recent attempt to address the problem uses the Shuttle Radar Topography mission(SRTm)data set to create the SRTm Water Body Data set(SWBD 2005).The SWBD represents a good first step but still requires additional work to expand the spatial coverage to include the whole globe and to address some erroneous discontinuities in major river *** address this issue a new water mask product has been created using the SWBD in combination with mODIS 250 m data to create a complete global map of surface water at 250 m spatial *** effort is automated and intended to produce a dataset for use in processing of raster data(mODIS and future instruments)and for masking out water in final terrestrial raster data *** new global dataset is produced from remotely sensed data and provided to the public in digital format,free of *** data set can be found on the Global Land Cover Facility(GLCF)website at http://*** dataset is expected to be a base set of information to describe the surface of Earth as either land or water which is a fundamental distinction upon which other descriptions can be made.

关键词： digital earth land cover remote sensing mODIS water

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

COmPOSITION AND RHEOLOGY OF POLYAmIDE-6 OBTAINED BY USING BI-AND TRI-FUNCTIONAL COUPLING AGENTS

引用

Chinese journal of Polymer Science 2013年第1期31卷 58-70页

作者： j.j.m. Slot E. van Ruymbeke P.A.m. Steeman materials Science Centre DSM Research Department of mathematics and Computer Science Eindhoven University of Technology

A statistical approach is developed, based on a monte Carlo method, in order to determine the statistical composition of a polyamide-6 sample composed of caprolactam （an AB-type monomer） and of a di-acid （A2 type） or a tri- acid （A3 type） as coupling agents. For this composition, the linear theological behavior of these systems is predicted using a tube-based theory. This allows us to show that while coupling agents of type A2 can be seen as flow improver, the effect of branching agents of type A3, depending on the synthesis recipe and the conversion level, can lead either to an increase or to a decrease of the viscosity. By adding specific amount of these agents, we also show that it is possible to obtain materials with the same zero-shear viscosity but with different shear thinning behavior. Furthermore, the polydispersity of linear samples of the same average number molecular weight, mn, is discussed in function of the amount of A2 monomers they contain. Ranging from 2 to 1.5, this difference in polydispersity is expected to have a significant influence on the processing behavior of such materials.

关键词： Polyamide-6 Random branching Statistical composition Rheology monte Carlo Tube theory.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

DIFFERENTIAL OPERATORS OF INFINITE ORDER IN THE SPACE OF RAPIDLY DECREASING SEQUENCES

引用

Acta mathematica Scientia 2016年第2期36卷 325-333页

作者： m.mALDONADO j.PRADA m.j.SENOSIAIN Department of mathematics Salamanca University

We consider the space of rapidly decreasing sequences s and the derivative operator D defined on it. The object of this article is to study the equivalence of a differential operator of infinite order; that is φ（D） =^∞∑k=0φkD^k.φk constant numbers an a power of ***, meaning, is there a isomorphism X （from s onto s） such that Xφ（D） = D^nX？. We prove that if φ（D） is equivalent to Dn, then φ（D） is of finite order, in fact a polynomial of degree n. The question of the equivalence of two differential operators of finite order in the space s is addressed too and solved completely when n = 1.

关键词： Ordinary differential operators sequence spaces operators on function spaces

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Cross-focusing of two chirped Gaussian laser beams and THz wave generation in plasmas of multi-ion species under a weakly relativistic and ponderomotive regime

引用

Plasma Science and Technology 2022年第10期24卷 1-11页

作者： m R jAFARI mILANI S REZAEI m j jAFARI Photonics and Quantum Technologies Research School Nuclear Science and Technology Research InstituteTehran 14665-678Iran Plasma and Fusion Research School Nuclear Science and Technology Research InstituteTehran 14399-51113Iran

The generation of terahertz(THz)waves via the beating of two high-intensity chirped Gaussian lasers in a multi-ion-species plasma is numerically studied by taking into account the weak relativistic and ponderomotive regime of *** coupled differential equations for beamwidth parameters are extracted by introducing the dielectric function of such plasma and using WKB and paraxial ray *** amplitude of THz radiation at beat frequency resulting from the nonlinear current density induced by the beat ponderomotive force of the cross-focusing of beams was *** impacts of the chirp frequency parameter,initial laser intensity and initial ionic species density(specifically,the presence of singly and doubly charged ions)in the plasma on THz generation were *** numerical results reveal that THz radiation generation strongly depends on the chirp frequency parameter.A specific range of chirp frequencies exists for self-focusing as well as THz generation with a'turning point',where the THz emission reaches its maximum *** results show that the strength of self-focusing and consequently the generated THz radiation are reduced by increasing the density of doubly charged ionic species in the plasma due to the suppression of the nonlinear effects.

关键词： laser–plasma interaction THz generation chirped Gaussian laser beams

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

microstructure and room temperature tensile properties of 1μm-SiCp/AZ31B magnesium matrix composite

引用

journal of magnesium and Alloys 2015年第2期3卷 155-161页

作者： m.j.Shen X.j.Wang m.F.Zhang B.H.Zhang m.Y.Zheng K.Wu College of Engineering Shenyang Agricultural UniversityShenyang 110866PR China School of materials Science and Engineering Harbin Institute of TechnologyHarbin 150001PR China Liaoning Provincial Gem Quality Supervision and Inspection Center Shenyang 110000PR China

In the present study,AZ31B magnesium matrix composites reinforced with two volume fractions(3 and 5 vol.%)of micron-SiC particles(1μm)were fabricated by semisolid stirring assisted ultrasonic vibration *** as-cast ingots were extruded at 350℃ with the extrusion ratio of 15:1 at a constant ram speed of 15 mm/*** microstructure of the composites was investigated by optical microscopy,scanning electron microscope and transmission electron *** characterization of the composites showed relative uniform reinforcement distribution and significant grain *** presence of 1μm-SiC particles assisted in improving the elastic modulus and tensile *** ultimate tensile strength and yield strength of the 5 vol.%SiCp/AZ31B composites were simultaneously improved.

关键词： magnesium matrix composite microstructure mechanical properties

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

STABLE AND UNSTABLE STATIONARY TRAjECTORIES

引用

Applied mathematics and mechanics(English Edition) 2005年第1期26卷 52-57页

作者： j.m.Soriano Departamento de Anlisis matemtico Facultad de MatemticasUniversidad de Sevilla Aptdo.1160 Sevilla 41808 Spain

The stability of stationary trajectories of a particular autonomous system is *** proof of the result is based upon continuation methods.

关键词： autonomous system continuation method trajectory critical point zero point stationary trajectory stable solution asymptotically stable

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Reconstructing the Time-Dependent Thermal Coefcient in 2D Free Boundary Problems

引用

Computers, materials & Continua 2021年第6期67卷 3681-3699页

作者： m.j.Huntul Department of mathematics College of ScienceJazan UniversityJazanSaudi Arabia

The inverse problem of reconstructing the time-dependent thermal conductivity and free boundary coefcients along with the temperature in a two-dimensional parabolic equation with initial and boundary conditions and additional measurements is,for the rst time,numerically *** inverse problem appears extensively in the modelling of various phenomena in engineering and *** instance,steel annealing,vacuum-arc welding,fusion welding,continuous casting,metallurgy,aircraft,oil and gas production during drilling and operation of *** literature we already know that this inverse problem has a unique ***,the problem is still ill-posed by being unstable to noise in the input *** the numerical realization,we apply the alternating direction explicit method along with the Tikhonov regularization to nd a stable and accurate numerical solution of nite *** root mean square error(rmse)values for various noise levels p for both smooth and non-smooth continuous time-dependent coef-cients Examples are *** resulting nonlinear minimization problem is solved numerically using the mATLAB subroutine *** exact and numerically simulated noisy input data are *** results presented for two examples show the efciency of the computational method and the accuracy and stability of the numerical solution even in the presence of noise in the input data.

关键词： Inverse identication problem two-dimensional parabolic equation free boundary Tikhonov regularization nonlinear optimization

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Finding the Time-dependent Term in 2D Heat Equation from Nonlocal Integral Conditions

引用

Computer Systems Science & Engineering 2021年第12期39卷 415-429页

作者： m.j.Huntul Department of mathematics College of ScienceJazan UniversityJazanSaudi Arabia

The aim of this paper is to find the time-dependent term numerically in a two-dimensional heat equation using initial and Neumann boundary conditions and nonlocal integrals as over-determination *** is a very interesting and challenging nonlinear inverse coefficient problem with important applications in various fields ranging from radioactive decay,melting or cooling processes,electronic chips,acoustics and geophysics to *** solvability theo-rems of these inverse problems are ***,since the problems are still ill-posed(a small modification in the input data can lead to bigger impact on the ultimate result in the output solution)the solution needs to be ***,in order to obtain a stable solution,a regularized objective function is minimized in order to retrieve the unknown *** two-dimensional inverse problem is discretized using the forward time central space(FTCS)finite-difference method(FDm),which is conditionally stable and recast as a non-linear least-squares minimization of the Tikhonov regularization ***,this is effectively solved using the mATLAB subroutine *** exact and noisy data are *** results for a few benchmark test examples are presented,discussed and assessed with respect to the FTCS-FDm mesh size discretisation,the level of noise with which the input data is contaminated,and the choice of the regularization parameter is discussed based on the trial and error technique.

关键词： Two-dimensional heat equation Neumann boundary conditions inverse identification problems Tikhonov regularization nonlinear optimization

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

A User-friendly model for Ransomware Analysis Using Sandboxing

引用

Computers, materials & Continua 2021年第6期67卷 3833-3846页

作者： akhtar Kamal morched Derbali Sadeeq jan javed Iqbal Bangash Fazal Qudus Khan Houssem jerbi Rabeh Abbassi Gulzar Ahmad Department of Computer Science&Information Technology National Center for Cyber SecurityUniversity of Engineering&TechnologyPeshawar25120Pakistan Department of Information Technology Faculty of Computing and Information TechnologyKing Abdulaziz UniversityJeddah21589Saudi Arabia Institute of Computer Sciences and Information Technology(ICS/IT) University of AgriculturePeshawar25130Pakistan Department of Industrial/Electrical Engineering College of EngineeringUniversity of Ha’ilHail1234Saudi Arabia Department of Electrical Engineering University of Engineering&TechnologyPeshawar25120Pakistan

Ransomware is a type of malicious software that blocks access to a computer by encrypting user’s files until a ransom is paid to the *** have been several reported high-profile ransomware attacks including WannaCry,Petya,and Bad Rabbit resulting in losses of over a billion dollars to various individuals and businesses in the *** analysis of ransomware is often carried out via sandbox environments;however,the initial setup and configuration of such environments is a challenging ***,it is difficult for an ordinary computer user to correctly interpret the complex results presented in the reports generated by such environments and analysis *** this research work,we aim to develop a user-friendly model to understand the taxonomy and analysis of ransomware ***,we aim to present the results of analysis in the form of summarized reports that can easily be understood by an ordinary computer *** model is built on top of the well-known Cuckoo sandbox environment for identification of the ransomware as well as generation of the summarized *** addition,for evaluating the usability and accessibility of our proposed model,we conduct a comprehensive user survey consisting of participants from various fields,e.g.,professional developers from software houses,people from academia(professors,students).Our evaluation results demonstrate a positive feedback of approximately 92%on the usability of our proposed model.

关键词： Ransomware sandbox user-friendly model survey

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

The analysis of composite laminated beams using a 2D interpolating meshless technique

引用

Acta mechanica Sinica 2018年第1期34卷 99-116页

作者： S.H.m.Sadek j.Belinha m.P.L.Parente R.m.Natal jorge j.m.A.César de Sá A.j.m.Ferreira Department of mechanical Engineering Faculty of EngineeringUniversity of Porto Institute of mechanical Engineering and Industrial management University of Porto

Laminated composite materials are widely implemented in several engineering constructions. For its relative light weight, these materials are suitable for aerospace, military, marine, and automotive structural applications. To obtain safe and economical structures, the modelling analysis accuracy is highly relevant. Since meshless methods in the recent years achieved a remarkable progress in computational mechanics, the present work uses one of the most flexible and stable interpolation meshless technique available in the literature—the Radial Point Interpolation method(RPIm).Here, a 2 D approach is considered to numerically analyse composite laminated beams. Both the meshless formulation and the equilibrium equations ruling the studied physical phenomenon are presented with detail. Several benchmark beam examples are studied and the results are compared with exact solutions available in the literature and the results obtained from a commercial finite element software. The results show the efficiency and accuracy of the proposed numeric technique.

关键词： Radial point interpolators RPIm Laminated beam meshless method

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：