THE SPACE-TIME FINITE ELEMENT METHOD FOR PARABOLIC PROBLEMS

Adaptive space-time finite element method, continuous in space but discontinuous in time for semi-linear parabolic problems is discussed. The approach is based on a combination of finite element and finite difference techniques. The existence and uniqueness of the weak solution are proved without any assumptions on choice of the spacetime meshes. Basic error estimates in L-infinity (L-2) norm, that is maximum-norm in time, L-2-norm in space are obtained. The numerical results are given in the last part and the analysis between theoretic and experimental results are obtained.

Exceptional family of elements and the solvability of complementarity problems in uniformly smooth and uniformly convex Banach spaces

The notion of “exceptional family of elements (EFE)” plays a very important role in solving complementarity prob- lems. It has been applied in finite dimensional spaces and Hilbert spaces by many authors. In this paper, by using the generalized projection defined by Alber, we extend this notion from Hilbert spaces to uniformly smooth and uniformly convex Banach spaces, and apply this extension to the study of nonlinear complementarity problems in Banach spaces.

Mixed time discontinuous space-time finite element method for convection diffusion equations

A mixed time discontinuous space-time finite element scheme for secondorder convection diffusion problems is constructed and analyzed. Order of the equation is lowered by the mixed finite element method. The low order equation is discretized with a space-time finite element method, continuous in space but discontinuous in time. Stability, existence, uniqueness and convergence of the approximate solutions are proved. Numerical results are presented to illustrate efficiency of the proposed method.

A wideband fast multipole boundary element method for half-space/plane-symmetric acoustic wave problems

This paper presents a novel wideband fast multipole boundary element approach to 3D half-space/planesymmetric acoustic wave problems.The half-space fundamental solution is employed in the boundary integral equations so that the tree structure required in the fast multipole algorithm is constructed for the boundary elements in the real domain only.Moreover,a set of symmetric relations between the multipole expansion coefficients of the real and image domains are derived,and the half-space fundamental solution is modified for the purpose of applying such relations to avoid calculating,translating and saving the multipole/local expansion coefficients of the image domain.The wideband adaptive multilevel fast multipole algorithm associated with the iterative solver GMRES is employed so that the present method is accurate and efficient for both lowand high-frequency acoustic wave problems.As for exterior acoustic problems,the Burton-Miller method is adopted to tackle the fictitious eigenfrequency problem involved in the conventional boundary integral equation method.Details on the implementation of the present method are described,and numerical examples are given to demonstrate its accuracy and efficiency.

Design Elements of Urban Children' s Recreational Landscape Space Based on Genius Loci

Urban children's recreational landscape space is an organic component of urban children's recreational space,genius loci is both a result and a motive in its design.This paper interpreted the connotations of genius loci of urban children's recreational space,the correlation between both,and design elements of urban children's recreational landscape space,in order to provide theoretical support for the design of urban children's recreational landscape space.

SPACE-TIME FINITE ELEMENT METHOD FOR SCHRDINGER EQUATION AND ITS CONSERVATION

Energy conservation of nonlinear Schrodinger ordinary differential equation was proved through using continuous finite element methods of ordinary differential equation; Energy integration conservation was proved through using space-time continuous fully discrete finite element methods and the electron nearly conservation with higher order error was obtained through using time discontinuous only space continuous finite element methods of nonlinear Schrodinger partial equation. The numerical results are in accordance with the theory.

Finite Element Method for a Kind of Two-Dimensional Space-Fractional Diffusion Equation with Its Implementation

In this article, we consider a two-dimensional symmetric space-fractional diffusion equation in which the space fractional derivatives are defined in Riesz potential sense. The well-posed feature is guaranteed by energy inequality. To solve the diffusion equation, a fully discrete form is established by employing Crank-Nicolson technique in time and Galerkin finite element method in space. The stability and convergence are proved and the stiffness matrix is given analytically. Three numerical examples are given to confirm our theoretical analysis in which we find that even with the same initial condition, the classical and fractional diffusion equations perform differently but tend to be uniform diffusion at last.

MAXIMAL ELEMENTS OF CONDENSING PREFERENCE MAPS IN LOCALLY CONVEX HAUSDORFF SPACES

Two existence theorems of maximal elements of condensing preference maps in locally convex Hausdorff spaces are proved which generalize the recent results of Mehta. One of them positively answers the open problem mentioned by Mehta.

ON THE SELECTION OF SHAPE FUNCTION SPACES OF TRIANGULAR PLATE ELEMENTS

Using the method of undetermined coefficients, we construct a set of shape function spaces of nine-node triangular plate elements converging for any meshes, which generalize Spect's element and Veubeke's element.

Finite Element Orthogonal Collocation Approach for Time Fractional Telegraph Equation with Mamadu-Njoseh Polynomials

Finite element method (FEM) is an efficient numerical tool for the solution of partial differential equations (PDEs). It is one of the most general methods when compared to other numerical techniques. PDEs posed in a variational form over a given space, say a Hilbert space, are better numerically handled with the FEM. The FEM algorithm is used in various applications which includes fluid flow, heat transfer, acoustics, structural mechanics and dynamics, electric and magnetic field, etc. Thus, in this paper, the Finite Element Orthogonal Collocation Approach (FEOCA) is established for the approximate solution of Time Fractional Telegraph Equation (TFTE) with Mamadu-Njoseh polynomials as grid points corresponding to new basis functions constructed in the finite element space. The FEOCA is an elegant mixture of the Finite Element Method (FEM) and the Orthogonal Collocation Method (OCM). Two numerical examples are experimented on to verify the accuracy and rate of convergence of the method as compared with the theoretical results, and other methods in literature.

当代上海城市街道空间管控实践中的观念与方法

聚焦当代上海城市街道空间管控实践,梳理其发展演进历程,并基于空间治理的视角,以管控观念与方法的变迁为线索,从目标、对象、机制和路径4个层面,对其展开深入解析。由此提出,自1990年代以来,在上海街道空间管控的发展过程中,管控对象经历从要素到空间的迭代,管控机制发生从碎片化到整体化的转变;同时,有序与活力这一对管控目标在不同阶段交替出现,运动式治理与常规型治理这两种管控路径在实践探索中互为补充,共同推动街道空间品质螺旋上升,治理效能不断提高。

从空间规划体系到国土空间体系——兼析国土空间体系构建下的国土空间治理趋向

研究目的:分析国家治理体系和治理能力现代化背景下,国土空间体系表述的形成脉络及内在逻辑,并从国土空间体系构建视角探讨国土空间治理的未来趋向。研究方法:综合分析法与对比分析法。研究结果:国土空间具有“区域”和“要素”双重特性,建立空间规划体系旨在解决传统国土空间治理的“区域”“要素”缺乏统筹问题。从空间规划体系、国土空间规划体系到国土空间体系的演变,实质上是不断推进迈向高质量发展、强化“区域—要素”统筹的国土空间治理。在构建国土空间体系的指引下,国土空间治理既要聚焦国土空间的高质量发展,绘就国土空间协调发展蓝图,又要完善主体功能区战略和制度,做好国土空间治理的“区域—要素”统筹。研究结论:面向国土空间体系构建,国土空间治理未来应做好国土空间高质量发展导向下的“区域—要素”统筹治理。

吴文化元素在苏州地铁公共空间中的表达与应用

[目的]以城市地域文化传承为背景,探讨吴文化元素在苏州地铁公共空间中的融合与运用,总结吴文化元素在地铁公共空间的应用价值及策略。[方法]由吴文化兼收并蓄、崇文重教、柔中蓄劲、人巧天工等内涵出发,从典型性提炼、抽象化法则、文化符号重构三方面提出了吴文化元素的提取方法;利用案例分析法从设计说明、材料工艺、工艺施工及技术要求层面对苏州地铁出入口、站内公共艺术、车厢厢体吴文化元素的运用展开分析,详细介绍了吴文化建筑元素、园林元素、文化性格、餐饮文化、宗教信仰、语言文化、戏曲文化等方面对构建独特苏州地铁文化景观的具体做法。[结果及结论]通过吴文化元素提取的法则,建立吴文化符号设计系统、赋予吴文化符号功能及文化语义、运用现代设计手段实现传统文化在地铁公共空间转译传达,对传承城市文脉、塑造新时代城市精神,提升城市文化软实力具有推动意义。

场景理论视角下科技创新推动数字文化空间塑造研究

从场景理论的真实性、戏剧性和合法性三个维度出发,将数字文化空间的各空间要素与文化价值呈现相融合,探析科技创新应如何进一步推动数字文化空间塑造。从真实性维度提出要强化文化品牌IP意识、促进用户的文化认同;从戏剧性维度提出要满足异质性文化需要、激发用户自主创新动力;从合法性维度提出要保障网络信息安全,维护文化表达的平等权利。

基于激光雷达与遥感数据的地理空间要素识别方法

通过地理空间要素识别实现地理测绘和环境有效监测,提出基于激光雷达与遥感数据的地理空间要素识别方法。采用激光雷达的遥感监测方法实现对地理空间特征的对象集变化检测,根据地理空间测绘对象的纹理、形状、空间关系,采用遥感数据融合和空间信息表达方法实现对地理空间要素特征的专家知识融合,构建地理空间要素识别的遥感专家数据库。仿真结果表明,采用该方法进行地理空间要素识别的决策融合性较好。该方法也实现了对土地利用自然特征变化的检测,使得识别准确率的最大值可达到0.925,且识别耗时始终处于2.5 s以下。

地月空间全球治理规则框架构成要素研究

地月空间全球治理规则框架是构建地月空间治理规则体系的顶层指导,是争夺地月空间治理规则制定主导权的“先手棋”和关键所在,其构成要素研究具有重要意义。对政府间国际组织、重大国际合作项目、机构间和非政府3类不同平台的地月空间治理规则制定现状进行了综述,对《月球协定》《阿尔忒弥斯协定》等6个相关规则框架构成要素进行了研究,提出了涵盖4项基本原则和9类具体规则的地月空间全球治理规则框架构成要素,并给出了后续工作建议。

狭窄空间内矩形导体电流测量装置设计与优化

针对狭窄空间内矩形导体电流测量,提出了一种基于霍尔元件椭圆阵列的电流测量装置,通过理论计算和有限元仿真分析确定了相对最优的阵列分布,搭建实验平台并通过实验验证了该方法的可行性,以及导体偏心状态下电流测量的有效性,同时分析了导体偏心状态下的电流测量偏心误差。仿真和实验结果表明,椭圆阵列电流测量装置在行业允许的±1%误差限内,允许导线X轴偏心-4.1~4.1 mm,Y轴无限制;且与传统电流测量装置相比,重量减轻82.9%,安装占用面积减小72.4%,对狭窄空间的适用性更强,为新能源产品轻量化、小型化、持续降本提供了技术支持。

Maximal elements and generalized games involving condensing mappings in locally FC-uniform spaces and applications(Ⅰ)

First, the notions of the measure of noncompactness and condensing setvalued mappings are introduced in locally FC-uniform spaces without convexity structure. A new existence theorem of maximal elements of a family of set-valued mappings involving condensing mappings is proved in locally FC-uniform spaces. As applications, some new equilibrium existence theorems of generalized game involving condensing mappings are established in locally FC-uniform spaces. These results improve and generalize some known results in literature to locally FC-uniform spaces. Some further applications of our results to the systems of generalized vector quasi-equilibrium problems will be given in a follow-up paper.

冷却速率对ZG40CrNi2Mo大型铸件凝固组织及元素偏析的影响

为了研究铸件凝固过程中不同冷却速率对其凝固组织与元素偏析的影响,利用铸件凝固过程数值模拟方法和自研的高通量凝固过程热模拟实验装置,开展了ZG40CrNi2Mo优质调质钢在不同冷却速率下的凝固模拟实验。结果表明:ZG40CrNi2Mo调质钢的二次枝晶臂间距λ_(2)与局部凝固时间t的关系符合λ_(2)=36.03 t0.26;随着冷却速率的降低,Cr元素偏析呈现上升趋势,Ni元素偏析先上升后降低;Mo元素偏析最为严重,但是对于冷却速率的变化不敏感。

可信数据空间助力数据要素高效流通

数据要素目前已经上升到国家战略高度,而如何通过数字技术创新,在保障原始数据“可用不可见”前提下,安全可信的开展数据流通,是当下推动数据要素流通普及、普惠的重要议题。可信数据空间的建立能够有效地助力数据要素在安全、高效的环境下发挥最大价值,重点针对可信数据空间中的关键技术及重点应用方向进行探讨分析,为进一步深入开展可信数据空间研究提供参考。