甲烷浓度对金刚石薄膜(100)织构生长的影响

以H2和CH4的混合气体为气源,用微波等离子体辅助化学气相沉积法(MPECVD)在1 cm×1 cm S i(100)基体上沉积了金刚石薄膜。研究了不同的甲烷浓度对金刚石薄膜(100)织构生长趋势的影响。分别采用扫描电子显微镜(SEM),Ram an光谱对金刚石膜的表面形貌、质量进行了分析。结果表明,当基体温度为750℃,气压为4.8×103Pa,甲烷浓度为1.4%时,薄膜表面为(100)织构。     

鄂尔多斯盆地镇北地区三叠系延长组长8油组储层特征

鄂尔多斯盆地镇北地区延长组长8油层段是盆地重要的储集层之一。通过储层岩石学、储层物性、孔隙结构等方面对储层特征进行深入研究,研究结果表明,储层岩石类型主要为中细粒长石砂岩和岩屑长石砂岩,成分成熟度低,结构成熟度中—高;发育粒间孔隙、溶蚀孔隙、晶间孔等孔隙类型,喉道以中细喉—细喉为主。岩石物性总体较差,属低孔、低渗砂岩储层。研究结果对油田开发具有重要的指导意义。     

Autonomous tactile perception: A combined improved sensing and Bayesian nonparametric approach

In recent years, autonomous robots have increasingly been deployed in unknown environments and required to manipulate or categorize unknown objects. In order to cope with these unfamiliar situations, improvements must be made both in sensing technologies and in the capability to autonomously train perception models. In this paper, we explore this problem in the context of tactile surface identification and categorization. Using a highly-discriminant tactile probe based upon large bandwidth, triple axis accelerometer that is sensitive to surface texture and material properties, we demonstrate that unsupervised learning for surface identification with this tactile probe is feasible. To this end, we derived a Bayesian nonparametric approach based on Pitman–Yor processes to model power-law distributions, an extension of our previous work using Dirichlet processes Dallaire et al. (2011). When tested against a large collection of surfaces and without providing the actual number of surfaces, the tactile probe combined with our proposed approach demonstrated near-perfect recognition in many cases and achieved perfect recognition given the right conditions. We consider that our combined improvements demonstrate the feasibility of effective autonomous tactile perception systems.     

结合方向纹理熵的Haar-like特征在线boosting跟踪算法

针对传统基于Haar-like特征的on-line boosting跟踪算法（HBT）需要产生大规模随机特征、占用大量计算资源和存储空间的缺点,提出结合方向纹理熵的Haar-like特征在线boosting跟踪算法（HBTT）。HBTT算法利用灰度共生矩阵的熵获得目标纹理的方向信息,在此基础上有针对性地产生具有方向纹理信息的Haar-like特征,从而可有效避免无效随机特征的产生,减小特征池容量;更进一步,可根据目标纹理的复杂程度自动调整特征数量,使得算法更灵活。在跟踪过程中,在线学习模块可以使错误率较高的特征被结合了目标纹理方向信息的Haar-like特征所替换。与HBT算法比较,HBTT算法的跟踪误差降低了10%以上;在相同特征池容量下,置信度提高了2%以上。实验结果表明,该算法不仅具有较高的鲁棒性,而且在跟踪效率和性能上都有所提高。     

Margarines: A rheological study

Time-dependent flow properties of both commercial and pilot plant-made margarines were characterized under steady shear. Flow curves were fitted to the kinetic expression τ = τ _i +a e ^−k1t +b e ^−k2t . A first-order kinetic model did not describe the observed destruction process of the margarine structure in an adequate manner. In the proposed model, two structures with different destruction rates are postulated. Each structure contributes to a part of the shear stress necessary to deform the margarine sample. The parameters τ _i a andb are temperature-dependent. Decreasing temperatures produce an exponential increase of τ _i , a linear increase ofb and an increase ofa up to a point beyond which it remains constant. A physical interpretation of the model is proposed. The role of the aqueous phase was also studied. Greater hardness was detected at higher water content. Parameter τ _i increased, at any selected temperature, with increasing aqueous phase content of the sample. Parametera increased with decreasing temperatures and higher water content. On the other hand, parameterb was not affected by the amount of aqueous phase. This kinetic model could be employed to perform studies on the influence of different parameters of margarine formulation on its rheologic behavior.     

Molecular design and characterization of catalysts for NO x selective reduction by hydrocarbons in the oxygen excess based upon ultramicroporous zirconia pillared clays

Approaches to design of zirconia pillared clays via control of the properties of pillaring species in solutions were elaborated. Structural features of pillars and Pt + Cu active components fixed at these nanoparticles were shown to determine catalytic properties of pillared clays in NO_x selective reduction by hydrocarbons in the oxygen excess.     

Hero Wavelength Spectral Sampling

We present a spectral rendering technique that offers a compelling set of advantages over existing approaches. The key idea is to propagate energy along paths for a small, constant number of changing wavelengths. The first of these, the hero wavelength, is randomly sampled for each path, and all directional sampling is solely based on it. The additional wavelengths are placed at equal distances from the hero wavelength, so that all path wavelengths together always evenly cover the visible range. A related technique, spectral multiple importance sampling, was already introduced a few years ago. We propose a simplified and optimised version of this approach which is easier to implement, has good performance characteristics, and is actually more powerful than the original method. Our proposed method is also superior to techniques which use a static spectral representation, as it does not suffer from any inherent representation bias. We demonstrate the performance of our method in several application areas that are of critical importance for production work, such as fidelity of colour reproduction, sub‐surface scattering, dispersion and volumetric effects. We also discuss how to couple our proposed approach with several technologies that are important in current production systems, such as photon maps, bidirectional path tracing, environment maps, and participating media.     

Fluorinated γ-alumina aerogels and xerogels: characterisation and catalytic behaviour

The porosity of -alumina-based materials is an important parameter affecting the extent of fluorination (aerogels > commercial -Al₂O₃ > xerogels) and, consequently, also the textural, acidic and catalytic properties of the final fluorinated materials. Only the highly fiuorinated aluminas having strong Lewis acidic sites catalyse the isomerisation of CHF₂CHF₂ to CF₃CH₂F.     

热分解法制备纳米WO_3的结构特征及其分散行为研究

以钨酸铵为原料,在350～600℃不同温度下,用热分解法制备了纳米WO3。用透射电子显微镜、X射线衍射与电子衍射并结合热分析法,研究了热分解温度对纳米WO3的粒径大小、形状、晶型的影响,发现钨酸铵在225～375℃吸热分解,在400℃时完全分解为简单六方结构WO3和简单单斜结构WO3两相混合物,简单六方结构WO3在404℃左右向简单单斜结构WO3转变,500℃与600℃热分解产物都是简单单斜结构WO3。WO3粒径随温度升高而增大,分解温度从400℃升至600℃时,WO3粒径从20nm增大到100nm左右。用表面活性剂对纳米WO3进行表面修饰,发现两性型十二烷基二甲基甜菜碱可提高纳米WO3在水溶液与甲苯中的分散稳定性,沉降速度降低50%。     

GLCM based extraction of flame image texture features and KPCA-GLVQ recognition method for rotary kiln combustion working conditions

According to the pulverized coal combustion flame image texture features of the rotary-kiln oxide pellets sintering process,a combustion working condition recognition method based on the generalized learning vector(GLVQ) neural network is proposed.Firstly,the numerical flame image is analyzed to extract texture features,such as energy,entropy and inertia,based on grey-level co-occurrence matrix(GLCM) to provide qualitative information on the changes in the visual appearance of the flame.Then the kernel principal component analysis(KPCA) method is adopted to deduct the input vector with high dimensionality so as to reduce the GLVQ target dimension and network scale greatly.Finally,the GLVQ neural network is trained by using the normalized texture feature data.The test results show that the proposed KPCA-GLVQ classifer has an excellent performance on training speed and correct recognition rate,and it meets the requirement for real-time combustion working condition recognition for the rotary kiln process.