不同制备方法所得PEN纤维的结构性能比较

利用高速纺丝法与纺丝拉伸一步法两种不同的方法制备聚萘二甲酸乙二酯 ( PEN)纤维 ,以DSC、X射线衍射、声速、力学测试等手段分析其结构、热学及力学性能并进行比较。结果表明 :以上两种纺丝法所制备 PEN纤维的晶型、晶粒尺寸不同 ;在所采用的高速纺丝速度范围内 ,分别以 6,7,8km/m in的速度纺制的试样结构性能基本相同 ;而纺丝拉伸一步法中不同的拉伸倍数对纤维的取向度影响较大 ,进而使杨氏模量、断裂强度和断裂伸长率变化较大     

石油产品中硫醇硫含量测定的不确定度评估

根据国家标准GB/T1792-88《馏分燃料中硫醇硫含量测定法(电位滴定法)》的试验方法．考察评估了该项分析的测量不确定度。     

甘油三酸脂对硅溶胶的分散作用

通过对硅溶胶泥浆的流变性实验确定了硅溶胶泥浆的流变模型，验证并分析了加入少量经过低温氧化过的甘油三酸脂（ＧＴＯ）不改变硅溶胶泥浆的流变模型，但能有效地改善其流变性能。因此，ＧＴＯ可作为硅溶胶结合浇注料的高效减水剂。     

A randomized algorithm for natural object colorization

Natural objects often contain vivid color distribution with wide variety of colors. Conventional colorization techniques, on the other hand, produce colors that are relatively flat with little color variation. In this paper, we introduce a randomized algorithm which considers not only the value of target color but also the distribution of target color. In essence, our algorithm paints a color distribution to a region which synthesizes color distribution of a natural object. Our approach models the correlation between intensity and color in HSV color space in terms of H – S, H – V and S – V joint histogram. During the colorization process, we randomly swap and reassign color of a pixel to minimize a cost function that measures color consistency to its neighborhood and intensity‐to‐color correlation captured in the joint histogram. We tested our algorithm extensively on many natural objects and our user study confirms that our results are more vivid and natural compared to results from previous techniques.     

Laplacian colormaps: a framework for structure‐preserving color transformations

Mappings between color spaces are ubiquitous in image processing problems such as gamut mapping, decolorization, and image optimization for color‐blind people. Simple color transformations often result in information loss and ambiguities, and one wishes to find an image‐specific transformation that would preserve as much as possible the structure of the original image in the target color space. In this paper, we propose Laplacian colormaps, a generic framework for structure‐preserving color transformations between images. We use the image Laplacian to capture the structural information, and show that if the color transformation between two images preserves the structure, the respective Laplacians have similar eigenvectors, or in other words, are approximately jointly diagonalizable. Employing the relation between joint diagonalizability and commutativity of matrices, we use Laplacians commutativity as a criterion of color mapping quality and minimize it w.r.t. the parameters of a color transformation to achieve optimal structure preservation. We show numerous applications of our approach, including color‐to‐gray conversion, gamut mapping, multispectral image fusion, and image optimization for color deficient viewers.     

4D video textures for interactive character appearance

4D Video Textures (4DVT) introduce a novel representation for rendering video‐realistic interactive character animation from a database of 4D actor performance captured in a multiple camera studio. 4D performance capture reconstructs dynamic shape and appearance over time but is limited to free‐viewpoint video replay of the same motion. Interactive animation from 4D performance capture has so far been limited to surface shape only. 4DVT is the final piece in the puzzle enabling video‐realistic interactive animation through two contributions: a layered view‐dependent texture map representation which supports efficient storage, transmission and rendering from multiple view video capture; and a rendering approach that combines multiple 4DVT sequences in a parametric motion space, maintaining video quality rendering of dynamic surface appearance whilst allowing high‐level interactive control of character motion and viewpoint. 4DVT is demonstrated for multiple characters and evaluated both quantitatively and through a user‐study which confirms that the visual quality of captured video is maintained. The 4DVT representation achieves >90% reduction in size and halves the rendering cost.     

Optimizing BRDF orientations for the manipulation of anisotropic highlights

This paper introduces a system for the direct editing of highlights produced by anisotropic BRDFs, which we call anisotropic highlights. We first provide a comprehensive analysis of the link between the direction of anisotropy and the shape of highlight curves for arbitrary object surfaces. The gained insights provide the required ingredients to infer BRDF orientations from a prescribed highlight tangent field. This amounts to a non‐linear optimization problem, which is solved at interactive framerates during manipulation. Taking inspiration from sculpting software, we provide tools that give the impression of manipulating highlight curves while actually modifying their tangents. Our solver produces desired highlight shapes for a host of lighting environments and anisotropic BRDFs.     

Efficient Monte Carlo rendering with realistic lenses

In this paper we present a novel approach to simulate image formation for a wide range of real world lenses in the Monte Carlo ray tracing framework. Our approach sidesteps the overhead of tracing rays through a system of lenses and requires no tabulation. To this end we first improve the precision of polynomial optics to closely match ground‐truth ray tracing. Second, we show how the Jacobian of the optical system enables efficient importance sampling, which is crucial for difficult paths such as sampling the aperture which is hidden behind lenses on both sides. Our results show that this yields converged images significantly faster than previous methods and accurately renders complex lens systems with negligible overhead compared to simple models, e.g. the thin lens model. We demonstrate the practicality of our method by incorporating it into a bidirectional path tracing framework and show how it can provide information needed for sophisticated light transport algorithms.     

Living cationic polymerization of isobutyl vinyl ether (II): Photoinduced living cationic polymerization in a mixed solvent of toluene and diethyl ether

A new method of preparation of living cationic polymer of isobutyl vinyl ether via photoinduced polymerization in the presence of diphenyliodonium iodide (DPII, initiator) and zinc iodide in a mixed solvent of toluene/diethyl ether, which was irradiated at ?78°C for short period, was completed within 15 min. The reaction was allowed for further reaction in the dark until monomer was fully consumed. It was found that increase in the conversion of monomer to polymer during the irradiation is very limited. Confirmation of the linear dependence of number‐average molar mass of resulting polymer on % conversion together with the fact that polymerization proceeds until monomer consumption, and controllability of number‐average molar mass of resulting polymer, depending on the molar ratio of monomer and initiator, strongly suggests the living nature of this polymerization, unless reaction temperature becomes higher than 0°C, i.e., the absence of chain breaking process. The narrow molar mass distribution, whose polydispersity index values are less than 1.2, reveals that the rate of initiation where irradiation is usually completed within 15 min is much faster than that of propagation in cationic nature in this system. Effect of some major factors, such as solvent polarity and temperature, on the living nature of the polymerization was also investigated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3581–3586, 2006     

Effects of buffer layer materials and process conditions on growth mechanisms of forming networks of SWNTs by microwave plasma chemical vapor deposition

This study investigates the growth mechanism of IC compatible processes and to the feasibility of synthesizing networks of single-walled carbon nanotubes (SWNTs) at lower temperatures (610 °C) on Si wafer using microwave plasma chemical vapor deposition (MPCVD) with CH₄ and H₂ as source gases. The effects of the buffer layer materials (ZnS–SiO₂, Al₂O₃, AlON, and AlN ) and process conditions on growth of carbon nanostructures with Co as catalyst were also examined, where the buffer layers and Co catalyst were deposited in sequence by physical vapor deposition (PVD), followed by H-plasma pretreatment before deposition of carbon nanostructures. Additionally, the morphologies and bonding structures of carbon nanostructures were characterized by field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), and Raman Spectroscopy. Analytical results demonstrate that networks of SWNTs are more favorable to be synthesized by selecting proper buffer layer material (e.g., AlON), and under higher temperatures, thinner catalyst thickness (e.g., 5 nm) and lower CH₄ / H₂ ratio (e.g., 5 / 100 sccm/sccm). The networks of SWNTs can be fabricated at temperatures as low as 610 °C by manipulating these parameters. In conclusion, the growth mechanism determines the conditions for the formation of nano-sized extrusions on catalyst particles surface.