Non-Local Analysis of Forming Limits of Ductile Material Considering Void Growth

The current study performed a finite element analysis of the strain localization behavior of a voided ductile material using a non-local plasticity formulation in which the yield strength depends on both an equivalent plastic strain measurement (hardening parameter) and Laplacian equivalent. The introduction of gradient terms to the yield function was found to play an important role in simulating the strain localization behavior of the voided ductile material. The effect of the mesh size and characteristic length on the strain localization were also investigated. An FEM simulation based on the proposed non-local plasticity revealed that the load-strain curves of the voided ductile material subjected to plane strain tension converged to one curve, regardless of the mesh size. In addition, the results using non-local plasticity also exhibited that the dependence of the deformation behavior of the material on the mesh size was much less sensitive than that with classical local plasticity and could be succe

Variation analysis ofprecision mechanical assembly consideringform errors and local deformation

A method to analyze the effect of form errors and local deformation on the assembly accu- racy and its stability in a non-rigid assembly system is proposed. The contact finite element method was used to obtain local deformation of mating surfaces, which was superposed onto form errors to obtain real mating surface data of assemblies. Then mating variation was obtained by establishing vir- tual contact planes. Finally, an experiment of the assembly of two cylindrical components was car- ried out to verify the validity of the proposed method. By comparing the calculation accuracies of 3D assembly with and without taking into account local deformation, the results showed that the effects of local deformation of mating surfaces on calculation accuracy of mating variation was not neglect- able compared with form errors.

侧向约束下含拱玄武岩试样单轴压缩破坏行为研究

玄武岩作为岩浆岩的一种,广泛存在于人类活动的工程地质环境中。为研究含拱玄武岩的力学特征,本次试验运用水刀切割技术制作具有不同高跨比的含拱玄武岩试样,随后在刚性伺服机上对其进行侧限条件下的单轴压缩试验。分析了不同高跨比试样的峰值强度、破坏形态、裂隙类型和局部应变变化情况,以及拱的高跨比对含拱玄武岩试样裂纹扩展的影响。试验结果表明:随着拱高跨比的增加,试样峰值强度整体呈下降趋势,由于侧向约束的存在,试样峰值强度整体下降幅度较小,当拱的高度超过试样高度的1/2时,峰值强度降幅最大;拱的高跨比影响着裂纹的扩展方向,随着拱高跨比的增加,拱两侧破坏裂隙逐渐向中部靠拢,形成类倒漏斗形状,且试样中部的变形以微拉变形为主转变为以微压变形为主;试样的破坏过程总是由两侧的拱脚开始,逐渐出现岩屑剥落和裂纹起裂现象,随着加载的继续,拱脚处微裂纹逐渐向顶部扩展并贯通,导致试样最终完全破坏。

基于离子液射流定域电沉积的微镍柱成形研究

为提高定域电沉积三维金属微结构的加工效率和质量,采用离子液射流定域电沉积方式制备直径50~100μm、高度450~500μm的微镍柱,探究了工艺参数对沉积速率、微镍柱直径和微观形貌的影响。结果表明,在选定的参数范围内,微镍柱直径和沉积速率随着电压的增大同时增大,占空比对微镍柱沉积速率的影响高于对平均直径的影响,而脉冲频率对于微镍柱沉积速率影响不大。通过体式显微镜观察微镍柱微观形貌呈尖端效应,表明在阳极尖端半径对应区域和离子液射流范围内的共有区域具有电沉积定域性和优先性。合理控制阳极运动轨迹,调节参数为极间电压4.4 V、占空比50%、脉冲频率10 kHz时,可获得轮廓平直、表面致密的直径为61μm微镍柱。

L波段全国产化2.5 kW级脉冲模块设计

随着国防和民用技术的迅速发展,高性能的L波段脉冲模块成为雷达和通信领域的关键组件。文章介绍了一个全国产化的2.5 kW级L波段脉冲模块的设计流程。该模块采用先进的射频放大技术和脉冲形成网络设计,结合本土材料和工艺技术的优势,实现模块的高性能和低成本生产。仿真和实验验证表明,设计的模块满足了所有预期的技术参数,包括功率水平、脉冲宽度和效率,通过了严格的质量控制和可靠性评估。

旋转测量状态下光斑中心定位方法

目前,对管道内腔为自由曲面的截面轮廓进行高精度测量是行业难题。拟将多个不同测量范围的激光位移传感器放置于管道内腔中,采用旋转的方式对内腔进行测量,将得到的测量数据进行归一化处理后获得被测管道内腔截面轮廓形状。分析测量过程中激光光斑的变化情况,针对光斑图像的多峰、散斑、平顶与形状变化等现象,提出了一种基于传统灰度重心法进行粗定位的距离倒数加权多项式插值亚像素光斑中心定位方法。采用中值滤波对光斑图像进行预处理,通过自适应阈值分割法从环境背景光强中分离出光斑中心定位区域。通过MATLAB仿真与灰度重心法、加权灰度重心法与高斯拟合法传统光斑中心定位方法相比,结果表明,光斑中心定位精度达到0.01 pixel,在激光光斑中心定位精度和稳定性方面有一定的改善,明显优于传统的光斑中心定位算法。

教育综合体的在地性表达研究——以广东石油化工学院为例

文章从实际案例着手,探索以“在地性”理念为指导的高校建筑设计方法。以场地分析研究为基础,以具体的数据和翔实的资料为佐证,分析了广东石油化工学院教学管理的功能特点,由此开展现代教育建筑空间设计手法的研究。在设计过程中,文章分析了当地的气候特点、造价控制、技术水平等地域性要素的影响,并在其中融入了“自然观”的设计思想,基于限价设计的标准,完成了一座符合地域性特点的现代教育综合体。文章最终得出结论,“在地性”理念指导下的校园建筑设计能够更好地展现高校建筑特色,塑造场所精神特征,从而形成校园的永久记忆。

机场转型中的地方性研究

以场所理论为基础,对地方性在早期机场、机场城、空港都市区的表征与影响进行研究。应依据不同城市的地域文化特点,赋予机场历史性内涵,提升旅客在机场空间中的社交参与感,并建立情感纽带。分析高度标准化、统一化的规划模式在机场场所营造中的局限性,提出有机的发展过程对于实现地方性必不可少,并注重以人为本、孕育场所精神,由此使机场作为新城市形态,成为真正的“地方”。

党校建筑形式的探究与创新——浙江台州市委党校整体规划与设计实践

党校建筑具有特殊的学校属性,对于建筑形式有其标识性及地方的文化性,建筑形式的创新对党校的发展具有重要意义。文章以浙江台州市委党校项目设计实践为例,从建筑布局形式、建筑空间形式、建筑造型形式、建筑细节形式及建筑形式下建材的探究与创新等多个方面对党校的建筑形式进行探究与创新。台州市委党校创作了具有标识性及党校属性的建筑形式,给新时代建筑师参与党校建筑的设计实践提供了参考及宝贵启示。

本土化语境下汉字书法艺术的形意结合设计探析

中国汉字的发展历经数千年漫长岁月,是承载我国民族文化底蕴的重要载体。以汉字为依托的书法艺术,作为展现汉字之美的视觉艺术形态,给予了汉字在现代设计中新的方向,即回归本土化的同时又展现中国特有的气韵雅致之美。本文将通过分析形式美、意境美的艺术语言在汉字书法艺术中的设计应用,展现形意结合下的汉字书法在设计中的蓬勃生命力,以艺术的力量赋予其在当代新的生命。

基于SQL*Forms的图书馆管理系统建设

论述了构建图书馆局域网和利用SQL Forms开发图书馆管理系统的关键技术 。

THE LARGE TIME GENERIC FORM OF THE SOLUTION TO HAMILTON-JACOBI EQUATIONS

We use Hopf-Lax formula to study local regularity of solution to Hamilton- Jacobi （HJ） equations of multi-dimensional space variables with convex Hamiltonian. Then we give the large time generic form of the solution to HJ equation, i.e. for most initial data there exists a constant T 〉 0, which depends only on the Hamiltonian and initial datum, for t 〉 T the solution of the IVP （1.1） is smooth except for ~ smooth n-dimensional hypersurface, across which Du（x, t） is discontinuous. And we show that the hypersurface 1 tends asymptotically to a given hypersurface with rate t-1/4.

铝合金板料成形间距对逐点连续电磁成形过程的影响规律

电磁成形具有高速成形和提高材料塑性成形性能的特点,非常适用于准静态下难加工轻质铝合金材料的成形。在电磁系统中加入集磁器可以实现对工件的局部加工,但当电磁集中在小区域内多次成形时,由于两个成形点的距离较小,存在局部变形相互影响的区域,从而影响板料成形的均匀性。为研究逐点连续电磁成形过程中局部变形之间的相互作用机理,采用数值模拟结合实验验证的方法,探究了金属板料小区域逐点连续电磁成形过程中的变形行为,揭示了成形间距对板料成形涉及的电磁力、应变和最终成形效果的影响规律。研究结果表明,在单次电磁成形时,板料受到的电磁力呈环状分布,成形点中心受到径向与切向压应变和轴向拉应变,成形点四周受到径向拉应变和轴向与切向的压应变。在多次成形时,随着两成形点间距减小,板料在第二次成形时受到变形区的影响,影响间距为14 mm,板料中心所受的径向压应变和轴向拉应变增大,板料电磁力逐渐增大。第二成形点中心的成形高度随着两成形点间距的增加逐渐增加,两个成形点衔接处的凹槽深度也越深,而两个成形点衔接处的径向拉应变随着成形间距的增加表现为先增大后减小的趋势。本研究为在铝合金板料多点电磁成形过程中两点变形间距对电磁力和成形效果的影响提供了理论依据。

Necessary and Sufficient Conditions for a Class Positive Local Martingale

Let X be a Markov process, which is assumed to be associated with a (non-symmetric) Dirichlet form (E,D(E)) on L2 (E;m).?For , the extended Dirichlet space, we give necessary and sufficient conditions for a multiplicative functional to be a positive local martingale.

A local-world evolving hypernetwork model

Complex hypernetworks are ubiquitous in the real system. It is very important to investigate the evolution mecha- nisms. In this paper, we present a local-world evolving hypernetwork model by taking into account the hyperedge growth and local-world hyperedge preferential attachment mechanisms. At each time step, a newly added hyperedge encircles a new coming node and a number of nodes from a randomly selected local world. The number of the selected nodes from the local world obeys the uniform distribution and its mean value is m. The analytical and simulation results show that the hyperdegree approximately obeys the power-law form and the exponent of hyperdegree distribution is 7 = 2 ＋ 1/m. Furthermore, we numerically investigate the node degree, hyperedge degree, clustering coefficient, as well as the average distance, and find that the hypemetwork model shares the scale-flee and small-world properties, which shed some light for deeply understanding the evolution mechanism of the real systems.

Conservation form of Helbing's fluid dynamic traffic flow model

A standard conservation form is derived in this paper.The hyperbolicity of Helbing＇s fluid dynamic traffic flow model is proved,which is essential to the general analytical and numerical study of this model.On the basis of this conservation form,a local discontinuous Galerkin scheme is designed to solve the resulting system efficiently.The evolution of an unstable equilibrium traffic state leading to a stable stop-and-go traveling wave is simulated.This simulation also verifies that the model is truly improved by the introduction of the modified diffusion coefficients,and thus helps to protect vehicles from collisions and avoide the appearance of the extremely large density.

INSIDE BEADING OF A HEXAGONAL TUBE BY ELECTROMAGNETIC FORMING

In this paper local compressive deforming of a hexagonal tube of aluminum (JISA1050) is investigated by an electromagnetic forming. The hexagonal tubes are annealed for 1h. at 400℃， which have 55mm width with 1mm thickness, and 10mm corner edius. The deformed ation of the hexagonal tube, i.e., bead width, is 10, 15, 20mm, respectively. The magnetic flux density in the gap between the field shaper and the external surface of hexagonal tube is measured, and the result is that the magnetic flux density for a given voltage is almost identical along the gap) and decreases with increasing the gap. The profiles and the strain distribution of the hexagonal tube de- formed are affected by the change Of the charging voltage and the dimensions of a bead width. The greater compressive strum in the cireuwtrential direction is develOPed on plane part near corner,while tensile strain on the corner occurs. A metallic block is inserted inside the hexagonal tube so that uniform profile can be obtained. The simulation of the forming is performed by a finite-element method and compared with the experimental results.

Study on Continuity of Temple of Local Land God in Rural Construction Based on the Perspective of Place Spirit

Temple of local land god is a kind of traditional sacrificial architecture in China's village,and is cultural landscape generated under special farming system of China,which reflects the spiritual world of the working people and bears the history of the village. Its protection and continuity must take inheriting the cultural spirit as the most important prerequisite,and "place spirit" established by Norberg Schultz provides important theoretic basis for it. In this paper,based on "place spirit","place spirit" of temple of local land god is interpreted,and important role of "place spirit" in its protection and continuity and the ways to create "place spirit" of temple of local land god are explored.