彩电曲面形变

无论显示技术，还是外观形状和尺寸，彩电行业从未停止不断自我革新的步伐。从CRT到液晶、再到OLED的显示技术变革，推动着彩电外观形状由厚重的方块，逐渐变得纤薄，甚至弯曲起来。《电器》记者2015年5月走访北京家电卖场时发现，曲面电视已经不再是稀罕物，彩电的再度形变已经逐渐为消费者所了解。

S^n中保持高斯映射的曲面形变充分条件研究

给定一个2维定向黎曼流形M到单位球面Sn的一个等距浸入f:M→Sn Rn+1,证明了存在另一个浸入 f:M→Sn,使得f与 f具有相同的高斯映射的充分条件.

开卷有益 妙用Real-DRAW PRO曲面形变

在图片编辑软件中，具有直线透视形变功能的为数不多，而具有随意曲面形变功能的更是少见。所谓曲面形变，就是为图像的轮廓赋予曲线句柄，使之很容易弯曲变形，甚至卷曲起来。下面我们就用Real-DRAW PRO这款图像编辑软件为平台（如图1)．来制作一个画册翻页的图像效果。这种效果可用在贺卡、幻灯或同页中。

凸超曲面形变为预定调和平均曲率的曲面

使用热流方法将环形域中的凸超曲面形变为其调和平均曲率是一个预定函数的超曲面 .

Minkowski空间中的常负曲率类空曲面的形变

利用可积系统的思想 ,借助三维Minkowski空间L3的矩阵模型 ,我们研究了L3中常负曲率的类空曲面的形变及其可积性。

基于三维形变曲面模型的脊椎分割方法

针对医学图像中脊椎分割的难题,提出一种基于三维形变曲面模型的分割方法.首先,为防止过度分割,在原有"气球"模型的基础上,重新设计一种模型约束力(对流力).其次,利用图像边界与区域信息,得到整体能量函数方程.在图像力和模型约束力的共同约束下,新模型沿着能量函数极小化的方向进行水平集演化,形变模型逐步演化成人体脊椎的精确模型.实验表明,该方法能有效进行脊椎分割,解决了仅使用单一图像信息而造成分割精确度不够的问题.

等厚干涉的条纹宽度变化与球面的径向应变率关系的研究

等厚干涉的条纹宽度与薄膜厚度及入射光的波长宽度有关,因此可以通过测量等厚干涉的条纹宽度来测量入射光的波长宽度,以及通过测量条纹宽度变化率来测量曲面的变形率.

TOOTH CROWN DEFORMABLE DESIGN BASED ON DIRECT MANIPULATION OF FFD

A flexible and adaptable design method for the tooth crown is presented based on the direct manipulation of free-form deformation （FFD）. The correct shape of the tooth crown can be obtained by adding, modifying, and deleting constraint points or load points based on stretching and compressing operation. Finally, an example is given to illustrate the method to be efficient.

T2加权人脑MR体数据的脑提取

为了实现人脑T2加权MR图像的脑组织和非脑组织的分割,提出了一种基于三维形变曲面模型和数学形态学算法的MR T2图像脑提取方法。该方法分为两级提取:第一级提取依据脑解剖学知识,影像学知识及T2加权MR脑图像的组织在灰度直方图中的分布规律,应用三维形变曲面模型和区域生长实现脑的初级提取;第二级提取则根据图像的局部信息,应用六邻域结构元素对脑初级提取结果进行数学形态学处理,使脑提取结果更精确。实验结果表明,使用该方法对人脑T2加权MR数据进行脑提取的准确率能达到94%以上。算法性能评估证明本算法能够比较好地实现T2加权MR图像的脑提取。

一种基于脑MR图像的三层头模型自动分割方法

在求解脑电图EEG及脑磁图MEG正问题的过程中,常需要对人体组织中介电常数差距大的地方进行分层建模,以便更加准确的计算其传导矩阵。在人体脑部的各个组织中,颅骨和周围脑组织的介电常数差别尤其大。如何从脑MR图像中自动、准确地分割出颅骨部分,成为精确计算MEG/EEG正向传导矩阵的关键问题。而在磁共振图像(MRI)中,虽然软组织能被很清晰的成像,但颅骨却因为缺少氢而在图像中成像模糊,用传统的分割算法很难自动分割出准确的结果。为解决上述问题,本文提出一种结合脑组织平滑的先验信息和基于形变的曲面演化自动分割算法,来分割脑MR图像中的颅骨部分。再利用基于水平集的活动轮廓方法提取出头皮组织,进而构建出EEG及MEG正问题计算所需的三层真实头模型。我们将自动分割结果与手动分割结果进行了比较,证明了本文方法的有效性。

Effect of prestressed ultrasonic peen forming parameters on bending curvature and spherical deformation of plate

The elastic prestressed ultrasonic peen forming(UPF)was adopted in order to solve problems of insufficient bending deformation and large spherical deformation of plate during free UPF.The theoretical analysis of prestressed UPF and the influence of elastic prebending moment on deformation were analyzed.Spherical deformation coefficient was defined to quantificationally describe the spherical deformation.Experiments were conducted to compare the differences between free UPF and prestressed UPF processes and the effects of processing parameters on bending curvature and spherical deformation coefficient were studied.The results show that peening trajectory in chordwise direction is beneficial to enlarging spanwise bending deformation and decreasing spherical deformation coefficient.Large prebending curvature is helpful to increase spanwise bending deformation and decrease chordwise deformation,thereby obviously decreasing spherical deformation coefficient.Large spanwise deformation can be obtained under large firing pin velocity,small plate thickness and small offset distance.Large firing pin velocity plays a positive role in decreasing spherical deformation,while plate thickness and offset distance have little effect on it.Above all,prebending curvature and peening trajectory are the most important factors during prestressed UPF process.This study provides guidance for parameters optimization of prestressed UPF for wing plate with large thickness.

Cross-sectional distortion behaviors of thin-walled rectangular tube in rotary-draw bending process

The cross-sectional distortion usually appears during rotary-draw bending process of thin-walled rectangular tube with small bending radius.To study the cross-sectional distortion of the tube,a three-dimensional finite-element model of the process was developed based on ABAQUS/Explicit code and its reliability was validated by experiment.Then,the cross-sectional distortion behaviors of the tube were investigated.The results show that a zone of larger circumferential stress appears on the tube when bending angle reaches 30°.And in the larger circumferential stress zone,the sagging phenomenon is produced obviously.The maximum cross-sectional distortion is located in the larger circumferential stress zone and the angle between the plane of maximum cross-sectional distortion and the bending reference plane is about 50°.The position of the maximum cross-sectional distortion keeps almost unchanged with the variation of the clearances between dies and tube.

A model of deformation of thin-wall surface parts during milling machining process

A three-dimensional finite element model was established for the milling of thin-walled parts. The physical model of the milling of the part was established using the AdvantEdge FEM software as the platform. The aluminum alloy impeller was designated as the object to be processed and the boundary conditions which met the actual machining were set. Through the solution, the physical quantities such as the three-way cutting force, the tool temperature, and the tool stress were obtained, and the calculation of the elastic deformation of the thin-walled blade of the free-form surface at the contact points between the tool and the workpiece was realized. The elastic deformation law of the thin-walled blade was then predicted. The results show that the maximum deviation between the predicted value and the actual measured machining value of the elastic deformation was 26.055 μm; the minimum deviation was 2.011 μm, with the average deviation being 10.154 μm. This shows that the prediction is in close agreement with the actual result.

3D deformation effect and optimal excavated design of surface mine

The three-dimensional （3D） deformation effect of the slope engineering under the step-by-step excavation for the Antaibao surface mine was analyzed using the FLAC^3D technique. An optimal excavated scheme with a relatively steeper slope angle of 47° instead of 30° was successfully implemented at the west wall in the geological section 73200 of the mine area, where the 3D effect of the nonlinear large deformation of the slope was taken into account. Based on the above research conclusion, put forward the countermeasures of shortening mining length, excavating by different regions, timely foot backfilling to protect the excavated slope, and monitoring and feedback adjustment by studying the nonlinear effect. The results show that these countermeasures are effective in controlling maximum deformation and increasing the stability of the slope.

Effect of surface nanocrystallization and PPEC time on complex nanocrystalline hard layer fabricated by plasma electrolysis

Size distribution of nano-carbides produced by duplex treatments of surface nanocrystallization(by surface severe plastic deformation) and plasma electrolytic carburizing on CP-Ti was investigated.Skewness and kurtosis of Gussian shape distribution curves were studied and the effect of time was determined.The usage of longer time is more suitable for achieving less size of complex nano-carbides.Surface roughness of treated samples was measured.It is observed that there is an optimum level for time on surface roughness increasing(difference between two measured data).

Deformation behaviors of 21-6-9 stainless steel tube numerical control bending under different friction conditions

For contact dominated numerical control(NC) bending process of tube, the effect of friction on bending deformation behaviors should be focused on to achieve precision bending forming. A three dimensional(3D) elastic-plastic finite element(FE) model of NC bending process was established under ABAQUS/Explicit platform, and its reliability was validated by the experiment. Then, numerical study on bending deformation behaviors under different frictions between tube and various dies was explored from multiple aspects such as wrinkling, wall thickness change and cross section deformation. The results show that the large friction of wiper die-tube reduces the wrinkling wave ratio η and cross section deformation degree ΔD and increases the wall thinning degree Δt. The large friction of mandrel-tube causes large η, Δt and ΔD, and the onset of wrinkling near clamp die. The large friction of pressure die-tube reduces Δt and ΔD, and the friction on this interface has little effect on η. The large friction of bending die-tube reduces η and ΔD, and the friction on this interface has little effect on Δt. The reasonable friction coefficients on wiper die-tube, mandrel-tube, pressure die-tube and bending die-tube of 21-6-9(0Cr21Ni6Mn9N) stainless steel tube in NC bending are 0.05-0.15, 0.05-0.15, 0.25-0.35 and 0.25-0.35, respectively. The results can provide a guideline for applying the friction conditions to establish the robust bending environment for stable and precise bending deformation of tube bending.

An inequality of the holomorphic invariant forms

Let ωα （α=1,…,n） be the holomorphic invariant forms introduced by the author previously ona bounded domain D in Cn for n ≥ 2. Set ωα=（i/2）α ωα.Then for any complex surface S in D we have ω2/1｜S≥ω2｜s.

Classification of hypersurfaces with constant Laguerre eigenvalues in R^n

Let x:M → Rn be an umbilical free hypersurface with non-zero principal curvatures.Then x is associated with a Laguerre metric g,a Laguerre tensor L,a Laguerre form C,and a Laguerre second fundamental form B,which are invariants of x under Laguerre transformation group.An eigenvalue of Laguerre tensor L of x is called a Laguerre eigenvalue of x.In this paper,we classify all oriented hypersurfaces with constant Laguerre eigenvalues and vanishing Laguerre form.

Stabilization of 4-manifolds

The complex surface X obtained by 8 points blown up on CP2 and Barlow’s surface Y are homeomorphic,but not diffeomorphic.Using the Gromov-Witten invariant Ruan showed that the stabilized manifolds X×S2and Y×S2are not deformation equivalent.In this note,we show that the stabilized manifolds X×S1and Y×S1are diffeomorphic and non-deformation equivalent in cosymplectic sense.

A morphing machining strategy for artificial bonet

In this work, a novel morphing machining strategy （MMS） is proposed. In the method, the workpiece is progressively carved out from the stock. Pitfalls in conventional iso-height strategy, such as sharp edges and unevenly distributed left-over materials, are overcome. Moreover, to calculate different levels in the MMS, an energy-based morphing algorithm is proposed. Finally, the proposed strategy is employed in the machining of artificial bone represented by a T-spline surface. The excellent properties of T-spline, such as expressing complex shapes with a single surface, have been well adopted to artificial bone fabri- cation. Computer simulation and the actual machining of the middle finger bone show the feasibility of the proposed strategy.