田间小麦叶片无损监测方法的实现及旗叶几何表型定量

[目的]对田间小麦叶片进行无损监测,从数字图像处理的途径探讨田间小麦旗叶几何表型的测试方法,以期建立小麦旗叶几何表型与氮肥管理的关系。[方法]以宁麦13为试验材料,对其进行不同的氮肥处理,并采用数码相机及辅以数字图像处理的技术手段,探讨小麦旗叶的叶面积、长度和平均宽度与施氮量的关系。[结果]肥料处理是影响小麦旗叶几何表型的重要环境因子,不同的氮处理可令旗叶面积变化达4倍,小麦旗叶长度也可从15.87 cm增长到25.33 cm,因此小麦旗叶几何表型是鉴定前期肥料供应量的显著特征。旗叶表型与氮处理之间的高精度拟合关系表明该无损检测技术是研究小麦田间表型、氮肥及环境因子响应规律的可靠技术手段。[结论]该研究表明使用带标尺刻度的动态背景板数字图像处理技术是获取田间无柄及小叶作物几何表型的有效手段,其为田间条件下作物叶片器官生长动态的无损监测提供了一个可行的技术方案。

A Non-destructive Monitoring Technique for Wheat Leaf in Field and Quantification of Geometric Phenotype for Flag Leaf

[Objective] The aim was to conduct non-destructive monitoring on wheat leaf in field and discuss the method to measure geometric phenotype of flag leaf through digital image processing in order to establish relationship between geometric pheno- type of flag leaf and N fertilizer regulation. [Method] Ningmai 13 was applied with N fertilizers in different amounts to discuss relationship among area, length, average width of flag leaf and applied N fertilizers using digital camera and digital image pro- cessing technique. [Result] Fertilizer is a main environmental factor influencing geo- metric phenotype of flag leaf, for example, area of flag leaf would enlarge four times and the length would increase from 15.87 to 25.33 cm by different N fertilizer amount. Thus, geometric phenotype of flag leaf would reflect N fertilizer amount at early stage. The highly accurate relationship between phenotype and N fertilizer is a reliable tech- nique to study on rules of wheat phenotype, N fertilizer and environmental factors. [Conclusion] The research indicated that digital image processing technique with scale label and dynamic background plates is an effective method to obtain geometric phenotype of sessile crops and crops with little leaf, providing a feasible scheme for non- destructive monitoring on growth dynamic of leaf＇s organs.

A geometric Model for the Spatial Correlation of an Acoustic Vector Field in Surface-generated Noise

Spatial correlation of sound pressure and particle velocity of the surface noise in horizontally stratified media was demonstrated, with directional noise sources uniformly distributed on the ocean surface. In the evaluation of particle velocity, plane wave approximation was applied to each incident ray. Due to the equivalence of the sound source correlation property and its directivity, solutions for the spatial correlation of the field were transformed into the integration of the coherent function generated by a single directional source. As a typical horizontally stratified media, surface noise in a perfect waveguide was investigated. Correlation coefficients given by normal mode and geometric models show satisfactory agreement. Also, the normalized covariance between sound pressure and the vertical component of particle velocity is proportional to acoustic absorption coefficient, while that of the surface noise in semi-infinitely homogeneous space is zero.

3D surface topography formation in ultra-precision turning

The generation process of 3D surface topography in ultra-precision turning is analyzed, as the result of superimposing between actual roughness surface,waviness surface and geometrical form texture surface. From the viewpoints of machine technical system and manufacturing process,factors influencing on roughness surface, waviness surface and geometrical form texture surface in ultra-precision turning are discussed further.The 3D topography of ideal roughness surface and actual surface affected by cutting vibration are simulated respectively.

Surface reconstruction by offset surface filtering

The problem of computing a piecewise linear approximation to a surface from its sample has been a focus of research in geometry modeling and graphics due to its widespread applications in computer aided design. In this paper, we give a new algorithm, to be called offset surface filtering (OSF) algorithm, which computes a piecewise-linear approximation of a smooth surface from a finite set of cloud points. The algorithm has two main stages. First, the surface normal on every point is estimated by the least squares best fitting plane method. Second, we construct a restricted Delaunay triangulation, which is a tubular neighborhood of the surface defined by two offset surfaces. The algorithm is simple and robust. We describe an implementation of it and show example outputs.

FACE RECOGNITION FROM FRONT-VIEW FACE

This letter presents a face normalization algorithm based on 2-D face model to recognize faces with variant postures from front-view face. A 2-D face mesh model can be extracted from faces with rotation to left or right and the corresponding front-view mesh model can be estimated according to the facial symmetry. Then based on the inner relationship between the two mesh models, the normalized front-view face is formed by gray level mapping. Finally, the face recognition will be finished based on Principal Component Analysis (PCA). Experiments show that better face recognition performance is achieved in this way.

Human Body Modeling and Posture Simulating Based on 3D Surface Scan Data

This paper presents a new approach for modeling the human body by considering the motion state and the shape of whole body. The body model consists of a skeleton kinematic model and a surface model. The former is used to determine the posture of the body,and the latter is used to generate the body shape according to the given posture. The body surface is reconstructed with multi-segment B-spline surfaces based on the 3D scan data from a real human body.Using only a few joints parameters and the original surface scan data, the various body postures and the shape can be generated easily. The model has a strong potential of being used for ergonomic design,garment design, virtual reality environment, as well as creating human animation, etc.

Theorems of Erds-Ko-Rado type in geometrical settings

The original Erdos-Ko-Rado problem has inspired much research. It started as a study on sets of pairwise intersecting k-subsets in an n-set, then it gave rise to research on sets of pairwise non-trivially intersecting k-dimensional vector spaces in the vector space V（n, q） of dimension n over the finite field of order q, and then research on sets of pairwise non-trivially intersecting generators and planes in finite classical polar spaces. We summarize the main results on the Erdos-Ko-Rado problem in these three settings, mention the ErdSs-Ko-Rado problem in other related settings, and mention open problems for future research.

Analytical modeling of geometric errors induced by cutter runout and tool path optimization for five-axis flank machining

The cutter runout effect has significant influence on the shape of cutter swept surface and the machining surface quality. Hence,it is necessary to integrate the cutter runout effect in cutter swept surface modeling,geometric error prediction and tool path optimization for five-axis flank machining. In this paper,an envelope surface model considering cutter runout effect is first established,and geometric errors induced by runout effect are derived based on the relative motion analysis between the cutter and part in machining. In the model,the cutter runout is defined by four parameters,including inclination angle,location angle,offset value and the length of cutter axis. Then the runout parameters are integrated into the rotation surface of each cutting edge that is used to form the final cutter envelope surface for the five-axis machining process. Thus,the final resulting geometric errors of the machined surface induced by cutter runout can be obtained through computing the deviations from the nominal cutter swept surface. To reduce these errors,an iterative least square method is used to optimize the tool paths for five-axis flank machining. Finally,a validation example is given for a specific ruled surface. Results show the effectiveness and feasibility of the analytical model of geometric errors induced by cutter runout,and also show that the geometric errors can be reduced significantly using the proposed tool path planning method.