基于CFD-DEM的柔性生物质颗粒取向特性研究

为解决柔性生物质颗粒在食品加工和生物能源制备等出现的取向无序性问题,设计了一种三角形沟槽通道.基于计算流体动力学-离散元方法(CFD-DEM),建立三角形沟槽通道内柔性颗粒运动的气固耦合模型.其中,采用双链黏结球模型表征柔性生物质颗粒.设计正交实验,研究气体速度、颗粒长度、通道倾斜角和沟槽角度对柔性颗粒取向的影响规律.结果表明:柔性颗粒取向角为0~10°的比例高达0.9;通道倾斜角β对颗粒取向有序性的影响最大,随着颗粒长度颗粒的增大,通道倾斜角和沟槽角度的减小,取向有序性增强.优化模型中,颗粒取向角为0~10°的比例为0.96,取向有序参数S为-1.911,颗粒取向与沟槽方向基本一致;颗粒运动平均速度为2.467 m·s^(-1).该成果为颗粒取向的研究提供了一定的理论依据.

简论职业教育的特性和取向

特性是指事物的特征和属性,取向则是由事物特性所规定并选取的事物发展的应然倾向、趋向和向度。职业教育的特性和取向可以概括为生成性与过程取向、能育性与实践取向、价值性与超越取向以及整合性与创新取向,它们彼此依存、联系紧密,试根据实践研究对上述四方面特性和取向作出阐述。

偶氮苯侧链液晶聚合物膜快速不饱和光致取向研究

用薄膜透射率变化研究了偶氮液晶聚合物膜不同功率光照条件下的取向速度及取向稳定性,并用锥光干涉图确定了相应介晶基元的取向方向。实验结果表明介晶基元的取向速度和取向度随光照时间和光照功率增加而增加,超过一定功率阈值时,取向变得不稳定,光照时间增加而薄膜的取向度(透射率)反而降低。介晶基元的取向方向结果表明在阈值功率以上强度光照时,介晶基元发生了面内和面外两种取向。面外取向的介晶基元不稳定,在停止光照后容易发生解取向,聚合物膜的透射率降低。而面内取向的介晶基元则能稳定维持其取向状态,不会发生解取向。采用不饱和取向的方法可缩短取向时间95%,薄膜取向度提高1.3倍。4 ms的一次曝光足以使聚合物膜产生可读出、稳定的面内取向,取向的结果能保持2年不发生变化。

Mass Transfer and Axial Mixing Characteristics in a Coalescence-Dispersion Pulsed-Sieve-Plate Extraction Column

A new configuration of coalescence-dispersed pulsed-sieve-plate extraction column (CDPSEC) was developed, and the mass transfer and axial mixing characteristics were evaluated with the two-point dynamic method.The influence of operation conditions was discussed with experimental results, showing that the mass transfer performance of CDPSEC mainly depends on the energy input and the holdup of dispersed phase. Higher energy input results in higher holdup of the dispersed phase, the axial mixing of the continuous phase is suppressed, and the true height of mass transfer unit decreases markedly. On the other hand, higher energy input leads to more serious forward mixing of the dispersed phase, so the energy input should be limited. Accordingly the operation conditions were divided into two regions, and empirical correlations for predicting the mass transfer and axial mixing characteristics in different regions with a satisfactory accuracy were suggested.

Effect of asymmetric rolling on mechanical characteristics,texture and misorientations in ferritic steel

The mechanical and microstructural properties as well as crystallographic textures of asymmetrically rolled low carbon steel were studied.The modelling of plastic deformation was carried out in two scales:in the macro-scale,using the finite elements method,and in the crystallographic scale,using the polycrystalline deformation model.The internal stress distribution in the rolling gap was calculated using the finite elements method and these stresses were then applied to the polycrystalline elasto-plastic deformation model.Selected mechanical properties,namely residual stress distribution,deformation work,applied force and torques,and bend amplitude,were calculated.The diffraction measurements,X-ray and electron backscatter diffraction,enabled the examination of texture heterogeneity and selected microstructure characteristics.The predicted textures agree well with those determined experimentally.The plastic anisotropy of cold rolled ferritic steel samples,connected with texture,was expressed by Lankford coefficient.

Action Recognition from a Different View

In this paper,we propose a novel approach to recognise human activities from a different view.Although appearance-based recognition methods have been shown to be unsuitable for action recognition for varying views,there must be some regularity among the same action sequences of different views.Selfsimilarity matrices appear to be relative stable across views.However,the ability to effectively realise this stability is a problem.In this paper,we extract the shape-flow descriptor as the low-level feature and then choose the same number of key frames from the action sequences.Self-similarity matrices are obtained by computing the similarity between any pair of the key frames.The diagonal features of the similarity matrices are extracted as the highlevel feature representation of the action sequence and Support Vector Machines(SVM) is employed for classification.We test our approach on the IXMAS multi-view data set.The proposed approach is simple but effective when compared with other algorithms.

Microstructure characteristics and effect of grain orientation on magnetic properties of Fe_(63)Co_(32)Gd_5 alloy ribbons

By using the melt spinning techniques, the Fe63Co32Gd5 alloy ribbons with 15-50 m in thickness and 3-7 mm in width were prepared at the wheel speeds of 15, 20, 25 and 35 m/s. The rapid solidification microstructures were characterized by three layers, the middle layer of which reaches 80% thickness and forms the column grain of(Fe,Co) solid with Gd solution. Grain refinement takes place with the increase of the wheel speed. And after 0.5 h heat treatment at 823 K, the ribbon thickness becomes larger and the middle layer of column grain is very orderly perpendicular to the ribbon plane. The coercivity of quenched and annealed Fe63Co32Gd5 ribbons both have the inflection point at the wheel speed of 20 m/s, and the tendency is declining. The heat treatment processing makes the coercivity become lower by improving the order of(Fe,Co)17Gd2 compound. The saturation magnetization of quenched ribbons increases with the enhancement of wheel speed, whereas that of annealed ones decreases firstly and then increases. The minimum coercivity is 5.30×103 A/m and the maximum saturation magnetization is 163.62 A·m2/kg, which is obtained in the conditions of the wheel speed of 35 m/s and 0.5 h heat treatment at the temperature of 823 K.

A novel fusion method of improved adaptive LTP and two-directional two-dimensional PCA for face feature extraction

In this paper, under different illuminations and random noises, focusing on the local texture feature's defects of a face image that cannot be completely described because the threshold of local ternary pattern(LTP) cannot be calculated adaptively, a local three-value model of improved adaptive local ternary pattern(IALTP) is proposed. Firstly, the difference function between the center pixel and the neighborhood pixel weight is established to obtain the statistical characteristics of the central pixel and the neighborhood pixel. Secondly, the adaptively gradient descent iterative function is established to calculate the difference coefficient which is defined to be the threshold of the IALTP operator. Finally, the mean and standard deviation of the pixel weight of the local region are used as the coding mode of IALTP. In order to reflect the overall properties of the face and reduce the dimension of features, the two-directional two-dimensional PCA((2D)~2 PCA) is adopted. The IALTP is used to extract local texture features of eyes and mouth area. After combining the global features and local features, the fusion features(IALTP+) are obtained. The experimental results on the Extended Yale B and AR standard face databases indicate that under different illuminations and random noises, the algorithm proposed in this paper is more robust than others, and the feature's dimension is smaller. The shortest running time reaches 0.329 6 s, and the highest recognition rate reaches 97.39%.