Three-lobed shape bifurcation of rotating liquid drops

The evolution of axisymmetric equilibrium shapes of a rigidly rotating liquid drop can be extended beyond the 2-lobed shape bifurcation point if the rotating drop is driven in the n = 2 axisymmetric shape oscillation (perturbation), where n is the mode of oscillation. A reason for the extended stability of the perturbed rotating drop is that the inertia of the driven axisymmetric shape oscillation suppresses growth of a natural nonaxisymmetric shape fluctuation which leads to the 2-lobed shape bifurcation. The axisymmetric shape of the drop eventually bifurcates into either a 2- or a 3-lobed shape at a higher bifurcation point which is asserted to be the 3-lobed shape bifurcation point.     

声场中空化气泡的耦合振动及形状不稳定性的研究

计算了两个具有非球形扰动的气泡所组成系统的能量,并基于Lagrange方程得到了有声相互作用的非球形气泡的动力学方程和形状稳定性方程,研究了声场中非球形气泡间相互作用力对非球形气泡的形状不稳定性和气泡形状模态振幅的影响.研究结果表明声场中具有非球形扰动的气泡之间的耦合方式有两种:形状耦合模式和径向耦合模式,气泡之间的耦合方式取决于气泡形状扰动模态.由形状耦合及径向耦合产生的气泡之间的相互作用力能够改变单个气泡的形状不稳定及形状模态振幅,具体影响因素取决于声场驱动条件、气泡形状模态、相邻气泡的初始半径.     

Osmotically driven shape transformations in axons

We report a cylindrical-peristaltic shape transformation in axons exposed to a controlled osmotic perturbation. The peristaltic shape relaxes and the axon recovers its original geometry within minutes. We show that the shape instability depends critically on the swelling rate and that volume and membrane area regulation are responsible for the shape relaxation. We propose that volume regulation occurs via leakage of ions driven by elastic pressure, and analyze the peristaltic shape dynamics taking into account the internal structure of the axon. The results obtained provide a framework for understanding peristaltic shape dynamics in nerve fibers occurring in vivo.     

Different shape models for erythrocyte: Light scattering analysis based on the discrete sources method

In practical applications a precise and fast detection of the shape of a single erythrocyte from its scattering characteristics is needed. For this reason detailed investigations of light scattering properties of erythrocyte and their relation to shape is of great interest in recent years. In this paper we analyze light scattering behavior of different shape models of erythrocyte using the discrete sources method. For this we compare scattering results for oblate spheroid, disk-sphere, Cassini-based shape and a shape for a real strainless erythrocyte introduced by Skalak. Numerical results for the scattering indicatrix and the differential cross section by different shape models and its orientations are presented.     

基于球扩展光源模型的物体三维形状的恢复

计算机视觉中传统的物体三维形状恢复方法大都基于光源是无穷远点光源的假设，如由单幅图像恢复三维形状（ｓｈａｐｅｆｒｏｍｓｈａｄｉｎｇ）光度立体视觉（ｐｈｏｔｏｍｅｔｒｉｃｓｔｅｒｅｏ）方法等。实际环境中的光源往往不能满足这个假设，因此大大限制了这些方法的应用，本文提出了一种更加实用的球扩光源模型，并推导出此光源下反射物体表面的反射图，此模型在三维坐标系中描述了球光源位置，亮度，漫反射物体表面反射度与     

A Note on Unification of Translational Shape Invariant Potential and Scaling Shape Invariant Potential

This article puts forward a general shape invariant potential, which includes the translational shape invariant potential and scaling shape invariant potential as two particular cases, and derives the set of linear differential equations for obtaining general solutions of the generalized shape invariance condition.     

A Note on Unification of Translational Shape Invariant Potential and Scaling Shape Invariant Potential

This article puts forward a general shape invariant potential, which includes the translational shape invariant potential and scaling shape invariant potential as two particular cases, and derives the set of linear differential equations for obtaining general solutions of the generalized shape invariance condition.     

双布里渊放大池放大控制脉冲波形的研究

提出一种主放大池与修整放大池相结合的双布里渊放大池放大控制脉冲波形的新方法.在主放大池中，通过调节抽运光与种子光的延迟时间，完成对脉冲波形的整体控制；而在修整放大池中，通过调节双池间距，完成对脉冲波形、尤其是对脉冲前沿的微调.实验研究了双池间距对脉冲波形的影响，得到脉冲波形随双池间距的变化规律.结果表明：相遇时间及双池间距是控制脉冲波形最重要的参数.此双布里渊放大池系统可以方便地控制脉冲波形，尤其可以微调脉冲前沿. 关键词： 受激布里渊散射 布里渊放大 脉冲波形控制     

A molecular dynamics investigation of the deformation mechanism and shape memory effect of epoxy shape memory polymers

Following deformation, thermally induced shape memory polymers(SMPs) have the ability to recover their original shape with a change in temperature. In this work, the thermomechanical properties and shape memory behaviors of three types of epoxy SMPs with varying curing agent contents were investigated using a molecular dynamics(MD) method. The mechanical properties under uniaxial tension at different temperatures were obtained, and the simulation results compared reasonably with experimental data. In addition, in a thermomechanical cycle, ideal shape memory effects for the three types of SMPs were revealed through the shape frozen and shape recovery responses at low and high temperatures, respectively, indicating that the recovery time is strongly influenced by the ratio of E-51 to 4,4'-Methylenedianiline.     

基于谱线线型函数的气体浓度检测技术

快速、精确地测量微量气体浓度的技术在大气质量分析、环境污染检测等领域具有广泛的用途。在红外光谱检测技术中,气体吸收光谱的谱线线型函数是定量测量气体浓度的一个重要参量,而如何准确和快速地得到气体谱线线型函数值是气体浓度测量中的一个关键问题。首先从理论上分析了谱线线型函数,得出计算谱线线型函数的一般方法及探讨了气体浓度与谱线线型函数峰值之间的关系。然后,利用可调激光器及光谱仪检测系统测量了乙炔在1 515～1 545 nm波长范围内的吸收光谱,再通过Lambert-Beer定律计算得到在不同频率下的谱线线型函数峰值,最后利用程序拟合出该波段内气体的谱线线型函数峰值分布曲线,并与Voigt线型函数理论计算值进行了比较,发现理论计算的谱线线型函数峰值仍存在一定的偏差。相比理论计算结果,所提出的检测方法得到的乙炔浓度与真实的乙炔浓度值更加吻合,表明了通过实验确定的谱线线型函数的经验公式可以更好地用于气体浓度的检测。由于利用实验测量值获得了谱线线型函数峰值分布的拟合曲线,因此可以快速准确地计算出所对应的谱线线型函数峰值,从而大大地简化了线型函数的计算过程。实验所获得的数据可应用于光学遥测乙炔气体浓度,且提供的方法也可以应用到其他气体的谱线线型函数峰值的测量中。     

Shape invariant potentials in higher dimensions

In this paper we investigate the shape invariance property of a potential in one dimension. We show that a simple ansatz allows us to reconstruct all the known shape invariant potentials in one dimension. This ansatz can be easily extended to arrive at a large class of new shape invariant potentials in arbitrary dimensions. A reformulation of the shape invariance property and possible generalizations are proposed. These may lead to an important extension of the shape invariance property to Hamiltonians that are related to standard potential problems via space time transformations, which are found useful in path integral formulation of quantum mechanics.     

Shape change and fast M1 transitions in Kr

A shape transition from a probably asymmetric shape at low excitation to a more axial-symmetric shape above 21/2⁺ has been found in ⁸¹Kr. This shape change and the drastic increase of the M1 transition probabilities above spin 21/2 are attributed to the alignment of two g_9/2 protons.     

Shape memory effect and superelasticity in a strain glass alloy

The shape memory effect and superelasticity are usually found in alloys exhibiting spontaneous martensitic transformation. Thus it is hard to imagine that such interesting effects can appear in a system without a martensitic transformation. In this Letter we show shape memory and the superelasticity effect in a nonmartensitic Ti48.5Ni51.5 alloy, which has no martensitic transformation but undergoes a "strain glass" transition. In situ x-ray diffraction experiment showed that the shape memory and superelasticity in strain glass stem from a stress-induced strain glass to martensite transformation and its reverse transformation. The new shape memory and superelasticity in strain glass extends the regime of the shape memory effect and superelasticity and may lead to novel applications.     

平流层飞艇气动外形优化设计:螺旋桨的影响

建立综合螺旋桨影响的平流层飞艇气动外形优化设计平台.采用Hicks-Henne型函数法参数化艇身轮廓,发展IDW-TFI混合动网格技术实现变形网格高效生成;基于作用盘理论模拟螺旋桨,建立飞艇流场高效数值求解方法.以LOTTE飞艇作为初始外形,阻力系数最小为目标,飞艇体积作为约束条件,通过NLPQL算法寻优获得最佳艇身设计方案.优化后飞艇的尾部形状较平坦,艇身最大横截面位置前移,气动性能得到明显改善,其阻力系数相对于初始外形降低了26.88%.     

α能谱峰形函数及其拟合参数初始值获取

(1. 西南科技大学 核废物与环境安全国防重点学科实验室, 四川 绵阳 621010;2. 四川理工学院 化学与环境工程学院, 四川 自贡 643000;3. 成都理工大学 地质灾害防治与地质环境保护国家重点实验室, 成都 610059;4. 中国工程物理研究院 核物理与化学研究所, 四川 绵阳 621900) 根据能谱的形成机理,建立了一种能谱峰形函数,提出基于矩估计法确定该峰形函数的拟合参数初始值的方法。以数理统计为基础,分别通过峰形函数和离散谱峰数据计算均值、方差和三阶中心矩建立方程组求解获取拟合参数的初始值。通过连续气溶胶检测仪探测的氡子体能谱和低本底能谱仪探测的238Pu面源能谱对该峰形函数模型和初始值获取方法进行了测试。结果表明:从低重合度到高重合度,该峰形函数模型都能得到较好的应用;基于矩估计法确定该峰形函数的参数初始值能够使该峰形函数较好地拟合能谱数据。该方法在采用计算机自动能谱拟合分析中具有较强的实用性。     

一种基于光谱库的雪粒径及形状参数反演新方法

雪粒径的形状因素对积雪的反射光谱曲线影响较大,如何有效地刻画雪粒径的形状参数成为研究的热点。渐进辐射传输模型被广泛地应用于雪粒径反演,其对雪粒径形状的描述只采用了2个值(3.62对应于片状雪粒径,4.53为球形雪粒径),较难描述积雪的形状参数,同时为了反演积雪的雪粒径,这两个形状参数必须被提前固定,这大大降低了雪粒径的反演精度,为此提出了一种基于光谱库的雪粒径及形状参数反演算法(LUTMA)。首先利用渐进辐射传输模型建立不同粒径,不同形状参数的光谱库,然后采用光谱角指标进行匹配,最终获取积雪的粒径与形状参数。实验表明,基于光谱库的雪粒径及形状参数反演新方法与实测数据较为吻合。     

1.3GHz单cell高梯度低损耗超导腔设计研究

计划中的国际直线对撞机(简称 ILC), 已确定采用低温超导技术. 研究表明, ILC的整体造价与超导腔的加速梯度密切相关, 因此新型高梯度超导腔的研制, 已成为目前ILC的热门课题. 目前超导腔加速梯度的提高受限于超导体射频临界磁场(H_c^rf), 希望通过腔形的优化设计, 来减小超导腔表面峰值磁场与加速梯度的比值(H_p/E_acc), 进而提高超导腔的加速梯度, 以满足ILC的要求. 目前, 具有代表性的高梯度超导腔新腔形有两种, 即低损耗超导腔(LLSCC)和重入式超导腔(RESCC). LLSCC相对于RESCC而言, 具有较低的H_p/E_acc, 因此在理论上LLSCC更易于达到较高的梯度. 作者对1.3GHz单cell高梯度低损耗超导腔的腔形进行了详细的研究, 给出了相应低损耗超导腔腔形, 并对这一设计结果进行了分析比较.     

Hand shape recognition

Automated hand shape recognition has been studied over the past decade and some commercial systems have been developed. Despite these advances, there is not much open public literature discussing the hand shape verification research. This study proposes a method by using quadtree techniques, which are able to recognize the hand shape image within an extremely short time. The geometrical shape of a hand is a biometric characteristic of human beings, although it is different even for a twin sibling. This study uses a parallel grating to project onto the backside of a hand. The parallel grating will be distorted by the curvature shape of the hand and processed by image processing techniques for recognition. This study also presents our recognition results of 100 students captured over a period of time.