摄影中的面式构图

摄影构图中的"面"指的是由点与线构成的被摄体所呈现的形状,这种形状会给人以最为直观的视觉感受和最鲜明的主题意识。文章重点分析了三角形、L形、C形、O形、V形、框式和开放式的面式构图法。

镜面饰家巧思点点

镜子是家中司空见惯的日常生活必需品,如设在梳妆台上的梳妆镜、挂在门厅处的穿衣镜等等。镜子不但具有实用功能,而且以光亮的镜面、不同材质的外框和优美生动的式样装点着家家户户的居室。

Mastercam三维造型的有关探讨

Mastercam软件具有较低的硬件要求、运行效果稳定、易学易用、加工方式齐全的特点,在国内中小企业,特别是在模具行业用得较多的一个CAD/CAM集成软件,目前版本已升至Mastercam10。该文结合多年教学的体会,从坐标系、构图面入手,以Masterc-ma9为例,就造型的一些关键问题进行探讨。

Efficient rendering of breaking waves using MPS method

This paper proposes an approach for rendering breaking waves out of large-scale of particle-based simulation. Moving particle semi-implicit (MPS) is used to solve the governing equation, and 2D simulation is expanded to 3D representation by giving motion variation using fractional Brownian motion (fBm). The waterbody surface is reconstructed from the outlines of 2D simulation. The splashing effect is computed according to the properties of the particles. Realistic features of the wave are ren-dered on GPU, including the reflective and refractive effect and the effect of splash. Experiments showed that the proposed method can simulate large scale breaking waves efficiently.

First-principles Study of Single Tin-phthalocyanine Molecule on Ag（111） Surface

Adsorption behavior and electronic structure of tin-phthalocyanine (SnPc) on Ag(111) surface with Sn-up and Sn-down conformations are investigated using first-principles calculations. Two predicted adsorption configurations agree well with the experimentally determined structures. SnPc molecule energetically prefers to adsorb on Ag(111) surface with Sn-down conformation. The energy required to move the central Sn atom through the frame of a phthalocyanine molecule, switching from the Sn-up to Sn-down conformation, is about 1.68 eV. The simulated scanning tunneling microscopy images reproduce the main features of experimental observations. Moreover, the experimentally proposed hole attachment mechanism is verified based on the calculated density of states of SnPc on Ag(111) with three different adsorption configurations.

Structures of Facial Cycles and C-bridges of Embedded Graphs with Locally LEW-embedding Properties

In this paper, we show that for a locally LEW-embedded 3-connected graph G in orientable surface, the following results hold： 1） Each of such embeddings is minimum genus embedding; 2） The facial cycles are precisely the induced nonseparating cycles which implies the uniqueness of such embeddings; 3） Every overlap graph O（G, C） is a bipartite graph and G has only one C-bridge H such that C U H is nonplanar provided C is a contractible cycle shorter than every noncontractible cycle containing an edge of C. This extends the results of C Thomassen＇s work on LEW-embedded graphs.

Self-similarity Based Editing of 3D Surface Textures Using Height and Albedo Maps

This paper presents an inexpensive method for self-similarity based editing of real-world 3D surface textures by using height and albedo maps. Unlike self-similarity based 2D texture editing approaches which only make changes to pixel color or inten- sity values, this technique also allows surface geometry and reflectance of the captured 3D surface textures to be edited and relit us- ing illumination conditions and viewing angles that differ from those of the original. A single editing operation at a given location affects all similar areas and produces changes on all images of the sample rendered under different conditions. Since surface height and albedo maps can be used to describe seabed topography and geologic features, which play important roles in many oceanic proc- esses, the proposed method can be effectively employed in applications regarding visualization and simulation of oceanic phenom- ena.

Smooth cutting pattern generation technique for membrane structures using geodesic line on subplane and spline interpolation

Practical techniques for smooth geodesic patterning of membrane structures were investigated.For the geodesic search,adjustment of the subplane of the extracted elements series was proposed,and various spline approximation methods were used to flatten the strip for the generation of a smooth pattern.This search approach is very simple,and the geodesic line could be easily attained by the proposed method without the need for a difficult computation method.Smooth cutting patterning can also be generated by spline approximation without the noise in discrete nodal information.Additionally,the geodesic cutting pattern saved about 21%of the required area for the catenary model due to the reduction of the curvature of the planar pattern seam line.

Research on Building the Resource Library of Course Teaching based on the Cloud Computing

This paper puts forward sharing teaching resources based on cloud computing solutions, through the use of architecture means virtualization technology based on KVM on the server side, the infrastructure layer manage the underlying physical hardware equipment. In the realization of the infrastructure layer using Libvirt virtualization management suite that provides a common API development Web, through the RDP protocol, and finally access to the remote virtual desktop browser by the graphical user interface （GUI） and traditional Web B/S architecture, to simulate and access to low-level resources and sharing of teaching resources, teaching resources can be achieved education informatization in the process of teaching.

A fake projective plane constructed from an elliptic surface with multiplicities (2,4)

Given any (2,4)-elliptic surface with nine smooth rational curves,eight (2)-curves and one (3)-curve,forming a Dynkin diagram of type [2,2][2,2][2,2][2,2,3],we show that a fake projective plane can be constructed from it by taking a degree 3 cover and then a degree 7 cover.We also determine the types of singular fibres of such a (2,4)-elliptic surface.

Building a dense surface map incrementally from semi-dense point cloud and RGB images

Building and using maps is a fundamental issue for bionic robots in field applications. A dense surface map, which offers rich visual and geometric information, is an ideal representation of the environment for indoor/outdoor localization, navigation, and recognition tasks of these robots. Since most bionic robots can use only small light-weight laser scanners and cameras to acquire semi-dense point cloud and RGB images, we propose a method to generate a consistent and dense surface map from this kind of semi-dense point cloud and RGB images. The method contains two main steps： （1） generate a dense surface for every single scan of point cloud and its corresponding image（s） and （2） incrementally fuse the dense surface of a new scan into the whole map. In step （1） edge-aware resampling is realized by segmenting the scan of a point cloud in advance and resampling each sub-cloud separately. Noine within the scan is reduced and a dense surface is generated. In step （2） the average surface is estimated probabilistically and the non-coincidence of different scans is eliminated. Experiments demonstrate that our method works well in both indoor and outdoor semi-structured environments where there are regularly shaped objects.

Study of dynamic hydrophobicity of micro-structured hydrophobic surfaces and lotus leaves

The dynamic wetting characteristics of water droplets on silicon wafers with microscale regular pillars structures and fresh lotus leaves are investigated experimentally.We measured the static contact angle,contact angle hysteresis,and roll-off angle of water droplets on both of these superhydrophobic surfaces with a high speed contact angle meter.The dynamic contact angles and internal velocity distribution of water droplets on superhydrophobic surfaces were studied with a high-speed camera system and a particle image velocimetry (PIV) system,respectively.We found that the acceleration of water droplets when they slide off lotus leaves is greater than that of water droplets sliding off the silicon wafers with microscale pillar structures although the static contact angles of water droplets on lotus leaves are slightly smaller than those on the silicon wafers.The reason is that water droplets sliding off lotus leaves have smaller contact angle hysteresis and larger slip velocities.These results indicate that the dynamic contact angle hysteresis and sliding acceleration of liquid droplets are more suitable for reflecting the hydrophobicity of material surfaces compared with static contact angles.Our experiments also show that lotus leaves with multiscale micro/nanostructures have stronger hydrophobicity and self-cleaning properties compared with the micro-structured superhydrophobic surfaces.

Design and implementation of a software architecture for 3D-DDA

The three-dimensional discontinuous deformation analysis(3D-DDA) is a promising numerical method for both static and dynamic analyses of rock systems. Lacking mature software, its popularity is far behind its ability. To address this problem, this paper presents a new software architecture from a software engineering viewpoint. Based on 3D-DDA characteristics, the implementation of the proposed architecture has the following merits. Firstly, the software architecture separates data, computing, visualization, and signal control into individual modules. Secondly, data storage and parallel access are fully considered for different conditions. Thirdly, an open computing framework is provided which supports most numerical computing methods; common tools for equation solving and parallel computing are provided for further development. Fourthly, efficient visualization functions are provided by integrating a variety of visualization algorithms. A user-friendly graphical user interface is designed to improve the user experience. Finally, through a set of examples, the software is verified against both analytical solutions and the original code by Dr. Shi Gen Hua.

A New Fast Edge Detection Algorithm Based on NAM-structured Plane Decomposition

The nonsymmetry and antipacking pattern representation model （NAM）, inspired by the concept of the packing problem, uses a set of subpatterns to represent an original pattern. The NAM is a promising method for image representation because of its ability to focus on the interesting subsets of an image. In this paper, we develop a new method for gray-scale image representation based on NAM, called NAM-structured plane decomposition （NAMPD）, in which each subpattern is associated with a rectangular region in the image. The luminance function of pixels in this region is approximated by an oblique plane model. Then, we propose a new and fast edge detection algorithm based on NAMPD. The theoretical analyses and experimental results presented in this paper show that the edge detection algorithm using NAMPD performs faster than the classical ones because it permits the execution of operations on subpatterns instead of pixels.

Meristem control of leaf patterning

Plant organs are derived from stem cells.Once a leaf primordium initiates growth from the shoot apical meristem（SAM）,it establishes adaxial-abaxial（dorsal-ventral）polarity.This polarity essentially allows the leaf to become a flat structure with the lamina expanding along the juxtaposition,i.e.,the middle domain,between the adaxial and abaxial domains.