基于离散余弦变换和支持向量机的多光谱纹理图像的茶叶分类研究

提出一种利用多光谱图像纹理特征进行茶叶分类的新方法。图像由MS3100-3CCD光谱成像仪获得,光谱成像仪提供近红外(NIR)、红色(R)和绿色(G)的3个波段的图像。首先对原图像的NIR波段图像提取均方值,然后应用离散余弦变换算法,构造出8个带通和高通滤波器对NIR通道的图像进行滤波并提取均方差值,最后应用支持向量机技术,分别对原图像的NIR提取的均方差值和用8个滤波器滤过的图像提取的均方差值进行建模。茶叶样本总共为240个,训练和预测各为120个,每种训练样本和预测样本各为20个。结果表明经过8个滤波器处理图像的识别率为100%,而没有经过滤波处理的纹理图像识别率只有73.33%,说明离散余弦变换算法设计的滤波器是一种非常有效的纹理识别技术,此实验同时也为茶叶的分类提供一种快速和无损的新方法。     

The study of the mechanical impedance of foods and biomaterials to characterize their linear viscoelastic behavior at high frequencies

A new instrumental setup, which is based on the oscillatory squeezing flow model, was developed to characterize the viscoelastic properties of foods and biopolymers. Analysis of the data was performed by two different approaches. The first approach employed principles of vibration to determine viscous damping and elasticity of the sample harmonically compressed between two plates. The second approach involved the use of additional calculations based on the squeezing flow model which were linked to concepts of vibration analysis, such as mechanical impedance, to determine fundamental rheological parameters like complex viscosity and related (elastic and viscous) moduli. The experimental setup for the method is simple to use and could be attached to existing commercial instruments such as texture analyzers and universal testing machines. The use of the proposed method with this type of instruments would provide them with the additional capability of performing dynamic rheological testing. The dynamic mass of the instrument was significantly low when compared to that of other instruments that use similar principles. This low dynamic mass enabled the use of relatively higher frequencies for the testing of the samples. Comparison of the viscous and elastic moduli obtained with the proposed method and from conventional rheometers for a variety of foods and biopolymers showed good agreements.     

Existence of contralateral abnormalities revealed by texture analysis in unilateral intractable hippocampal epilepsy

We selected 23 patients with unilateral temporal lobe epilepsy characterized by ipsilateral hippocampal sclerosis and an apparently normal contralateral hippocampus on MR imaging. Images were acquired on a 0.28 T MR scanner using a conventional Carr-Purcell Meiboom Gill sequence in all patients and in 9 healthy subjects. Texture analysis was applied to axial MR images of the first and tenth echoes. Texture analysis detects macroscopic lesions and microscopic abnormalities that can not be observed visually. The presence of texture differences in the between normal (controls) and sclerotic hippocampi was ascertained by statistical discriminant analysis. The apparently normal contralateral hippocampi can be classified into three categories in terms of texture: 4 apparently healthy, 8 similar to sclerosis, and 11 different from either healthy or sclerosis. These findings are related to a certain degree of hippocampal alteration, which further investigation might help better characterize.     

A hierarchical model for rate-dependent polycrystals

A hierarchical model of a polycrystalline aggregate of rigid viscoplastic grains is formulated, and a robust and efficient computational algorithm for its solution is proposed. The polycrystalline aggregate is modeled as a binary tree. The leaves of the binary tree represent grains, and higher tree nodes represent increasingly larger sub-aggregates of grains. The root of the tree represents the entire polycrystalline aggregate. Velocity and traction continuity are enforced across the interface between the children of each non-leaf node in the binary tree. The hierarchical model explicitly models intergranular interactions but is nevertheless comparable in computational effort to the mean field models of polycrystal plasticity. Simulations of tensile, compressive, torsional, and plane strain deformation of copper lead to predictions in good agreement with experiments, and highlight the interconnection between grain deformations and intergranular constraints. It is inferred from the results that a hybrid mean field/hierarchical model represents a computationally efficient methodology to simulate polycrystal deformation while accounting for intergranular interactions.     

掺杂聚苯胺溶致液晶相的产生和表征

聚苯胺（PAN）具有共轭结构,从理论上满足形成液晶相的基本条件［1,2］．但由于聚苯胺难溶、难熔,长期以来对于聚苯胺溶液（尤其是浓溶液）或熔体的研究甚少．近年来,人们采用具有“增塑作用”的大分子功能质子酸对聚苯胺进行掺杂,获得可溶于多种有机溶剂中的掺杂态聚苯胺［3～5］．然而,聚苯胺溶液的结构与性能的特点及能否产生溶致液晶相等问题目前尚未见报道．为此,我们研究了十二烷基苯磺酸（DBSA）掺杂聚苯胺在有机溶剂中形成液晶相的条件,探讨了不同掺杂方法对PAN－DBSA的溶解性及形成液晶棺的影响;采用差式扫描量热分…     

On multiresolution schemes using a stencil selection procedure: applications to ENO schemes

This paper is devoted to multiresolution schemes that use a stencil selection procedure in order to obtain adaptation to the presence of edges in the images. Since non adapted schemes, based on a centered stencil, are less affected by the presence of texture, we propose the introduction of some weight that leads to a more frequent use of the centered stencil in regions without edges. In these regions the different stencils have similar weights and therefore the selection becomes an ill-posed problem with high risk of instabilities. In particular, numerical artifacts appear in the decompressed images. Our attention is centered in ENO schemes, but similar ideas can be developed for other multiresolution schemes. A nonlinear multiresolution scheme corresponding to a nonlinear interpolatory technique is analyzed. It is based on a modification of classical ENO schemes. As the original ENO stencil selection, our algorithm chooses the stencil within a region of smoothness of the interpolated function if the jump discontinuity is sufficiently big. The scheme is tested, allowing to compare its performances with other linear and nonlinear schemes. The algorithm gives results that are at least competitive in all the analyzed cases. The problems of the original ENO interpolation with the texture of real images seem solved in our numerical experiments. Our modified ENO multiresolution will lead to a reconstructed image free of numerical artifacts or blurred regions, obtaining similar results than WENO schemes. Similar ideas can be used in multiresolution schemes based in other stencil selection algorithms.      

Vegetable proteins and milk puddings

In recent years, interest in animal free foods has increased tremendously due to factors like BSE crisis, rise of nutritionally dependent illnesses, like diabetes type II, cardiovascular and digestive diseases, along with ethic orientations of denying animal intakes of any kind. The use of proteins from leguminous seeds as an alternative to the animal proteins in dairy desserts was studied. Lupin, pea and soya protein isolates were used in combination with κ-carrageenan, gellan and xanthan gum, in order to obtain a synergistic effect. Milk puddings were also produced for comparison. Texture studies suggested that mixed protein–polysaccharide systems, with vegetable proteins and κ-carrageenan or gellan gum, would be good systems to develop vegetable gelled desserts. Rheological oscillatory measurements were carried out to clarify the kinetics of gelation and characterise the microstructure of the best performing products. Results from time sweep tests showed that formulations with gellan gum present an industrial advantage over formulations with κ-carrageenan, since the maturation time for gellan gels is of the order of 5–10 h compared with 4–6 days in the case of κ-carrageenan. All the mixed gels presented the typical weak gel structure; therefore, it was possible to perform steady-state measurements, which allowed the observation of a shear-thinning behaviour for all gels.     

聚苯撑苯并二噻唑取向态凝固膜的织构研究

聚苯撑苯并二噻唑取向态凝固膜的织构研究丁建东，胡宇红，杨玉良（复旦大学高分子科学系，国家教委聚合物分子工程开放实验室，上海，２００４３３）关键词聚合物，液晶，织构主链型高分子液晶可制成高强度纤维，同时也提供了一种各向异性物体自组织结构的有效研究体系［...     

PW1700X射线衍射仪织构分析应用软件的功能开发

由Ｐｈｉｌｉｐｓ引进的ＰＷ１７００Ｘ射线衍射仪织构测量系统只能用反射法，按螺旋线扫测极目数据，测绘极角。α≤８５°的不完整极图。经功能开发后，建立了织构分析测算系统，织构分析应用软件包，包括不完整极图测量与ＯＤＦ（取向分布函数）计算，回算全极图与反极图，可彩色屏显考贝，并能进行织构的定量分析。适用于立方和六方品系多晶织构材料分析。近两年应用表明，软件功能优异。     

添加剂的吸附行为及其对Ni沉积层性能的影响

采用电化学及X射线衍射等方法研究有机添加剂苯磺酸钠、苯亚磺酸钠和糖精的吸附作用及其对Ni电沉积层的电化学活性、晶粒尺寸、织构及显微硬度的影响．结果表明，苯亚磺酸钠和糖精使Ni沉积层的电化学活性提高，（111）晶面的织构系数明显增大，而使（200）晶面的织构系数减小，还导致沉积层的晶粒尺寸显著减小和显微硬度提高；然而，苯磺酸钠对沉积层的活性及织构影响很小．讨论了上述添加剂的作用．