金属闪光外墙乳胶漆的研制及性能研究

以丙烯酸酯及有机硅单体为原料合成了核-壳型硅丙乳液,用自制分散剂将闪光铝粉分散成水性闪光铝粉浆,并成功分散于硅丙乳液中,加入进口助剂,配制成水性金属闪光外墙乳胶漆.讨论了基料的玻璃化温度、单体的加入方式、引发剂、乳化剂、反应温度、聚合工艺和pH等对乳胶漆性能的影响.     

Crystallinity and thermal properties of ethylene-1-decene copolymers

Summary Three copolymers of ethylene and 1-decene, covering a wide range of compositions, have been synthesized with a MgCl₂-supported Ziegler-Natta catalyst. The analysis by DSC and X-ray shows a great degree of heterogeneity in these copolymers and appreciable levels of crystallinity, corresponding to the orthorhombic lattice of polyethylene, are present even for very high 1-decene contents.     

Strong dependence on pressure of the performance of a Co/SiO2 catalyst in Fischer–Tropsch slurry reactor synthesis

A 10 wt% Co/SiO₂ catalyst was prepared by the incipient wet-impregnation method and tested in Fischer–Tropsch synthesis in a slurry reactor under conditions approaching industrial practice. The catalyst precursor was investigated by X-ray diffraction (XRD), temperature-programmed reduction (TPR), transmission electron microscopy (TEM) and photoelectron spectroscopy (XPS). The XPS and XRD techniques revealed the presence of a crystalline Co₃O₄ spinel-type phase, while-in addition-TEM and XPS analyses pointed to the formation of another amorphous Co₃O₄ spinel phase, both species interacting weakly with the silica substrate. The influence of total pressure on the conversion, selectivity and stability of the catalyst was studied. Upon increasing the overall pressure from 20 to 40 bar, not only activity increased but also the catalyst are not deactivating. These results are explained in terms of an increase of gases solubility in the solvent, this increment of CO concentration in the liquid phase favours carbonyl species formation and the cobalt particles segregation that implies an increase in the metal surface area.     

Styrene-butadiene branched star-shaped asphalt modifiers: Synthesis and mechanical characterization

Abstract

The synthesis and the corresponding characterization of styrene-butadiene (SB), branched, star-shaped copolymers was investigated as part of a research project on asphalt modification using polymers with precise molecular structures. The method of anionic polymerization was followed to prepare samples of block copolymers of SB, a synthesis method that controls chain-architecture, molecular weight distribution, monomer distribution, and the average molecular weight. The research studies are the synthesis of block copolymers including linear, three- and four-arms constructs, depending on the coupling agent used. The techniques of nuclear magnetic resonance (1NMR), differential scanning calorimetry (DSC), gel permeation chromatography (GPC), and rheology were carried out to characterize the copolymers. From the results of the 1NMR, DSC, and GPC analyses, all star-shaped copolymers investigated showed a similar block copolymer composition. Furthermore, the rheological behavior of one of the synthesized star-shaped copolymers was nearly the same as a four-branched commercial copolymer. Rheologically, the four-arm block copolymer sample had the largest storage modulus (G′) among the branched copolymers synthetized, indicating that such architecture produces a highly structured material. In regard to polymer-modified asphalt formulations, the three-branched copolymer architecture yielded better elastic behavior than the four-branch version. In summary, the findings of this investigation provide new insight about a polymer system that may offer advantages in industrial asphalt paving applications.     

A 2D algorithm with asymmetric workload for the UPC conjugate gradient method

This paper examines four different strategies, each one with its own data distribution, for implementing the parallel conjugate gradient (CG) method and how they impact communication and overall performance. Firstly, typical 1D and 2D distributions of the matrix involved in CG computations are considered. Then, a new 2D version of the CG method with asymmetric workload, based on leaving some threads idle during part of the computation to reduce communication, is proposed. The four strategies are independent of sparse storage schemes and are implemented using Unified Parallel C (UPC), a Partitioned Global Address Space (PGAS) language. The strategies are evaluated on two different platforms through a set of matrices that exhibit distinct sparse patterns, demonstrating that our asymmetric proposal outperforms the others except for one matrix on one platform.     

Leave-one-out cross-validation-based model selection for multi-input multi-output support vector machine

As an effective approach for multi-input multi-output regression estimation problems, a multi-dimensional support vector regression (SVR), named M-SVR, is generally capable of obtaining better predictions than applying a conventional support vector machine (SVM) independently for each output dimension. However, although there are many generalization error bounds for conventional SVMs, all of them cannot be directly applied to M-SVR. In this paper, a new leave-one-out (LOO) error estimate for M-SVR is derived firstly through a virtual LOO cross-validation procedure. This LOO error estimate can be straightway calculated once a training process ended with less computational complexity than traditional LOO method. Based on this LOO estimate, a new model selection methods for M-SVR based on multi-objective optimization strategy is further proposed in this paper. Experiments on toy noisy function regression and practical engineering data set, that is, dynamic load identification on cylinder vibration system, are both conducted, demonstrating comparable results of the proposed method in terms of generalization performance and computational cost.     

Dissecting the protocol and network traffic of the OnLive cloud gaming platform

Cloud gaming is a new paradigm that is envisaged to play a pivotal role in the video game industry in forthcoming years. Cloud gaming, or gaming on demand, is a type of online gaming that allows on-demand streaming of game content onto non-specialised devices (e.g. PC, smart TV, etc.). This approach requires no downloads or game installation because the actual game is executed on the game company’s server and is streamed directly to the client. Nonetheless, this revolutionary approach significantly affects the network load generated by online games. As cloud gaming presents new challenges for both network engineers and the research community, both groups need to be fully conversant with these new cloud gaming platforms. The purpose of this paper is to investigate OnLive, one of the most popular cloud gaming platforms. Our key contributions are: (a) a review of the state-of-the-art of cloud gaming; (b) reverse engineering of the OnLive protocol; and (c) a synthetic traffic model for OnLive.     

Poly(trimethylene terephthalate) nanocomposite fibers comprising different organoclays: Thermomechanical properties and morphology

Poly(trimethylene terephthalate) (PTT) nano composites were synthesized by in situ polymerization at high temperature with two thermally stable organoclays: 1,2‐dimethylhexadecylimidazolium‐montmorillonite (IMD‐MMT) and dodecyltriphenyl phosphonium‐MMT (C₁₂PPh‐MMT). PTT hybrid fibers with various organoclay contents were melt‐spun at various draw ratios (DRs) to produce monofilaments. The thermomechanical properties and morphologies of the PTT hybrid fibers were characterized using differential scanning calorimetry, thermogravimetric analysis, wide‐angle X‐ray diffraction, electron microscopy, and mechanical tensile properties analysis. The nanostructure of the hybrid fibers was observed by both scanning and transmission electron microscopy, which showed that the clay layers were well dispersed into the matrix polymer, although some clusters or agglomerated particles were also detected. Unlike the hybrids containing IMD‐MMT, the clay layers of the C₁₂PPh‐MMT hybrid fiber were more dispersed into the matrix polymer. The thermal stability and tensile properties of the hybrid fibers increased with increasing clay content for DR = 1. However, as DR increased from 1 to 9 the ultimate strength and initial modulus of the hybrid fibers with IMD‐MMT increased slightly whereas those of C₁₂PPh‐MMT hybrid fibers decreased slightly. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4535–4545, 2006     

烟气脱硫的发展、技术与产业化探讨

回顾了我国烟气脱硫的发展历程 ,总结了我国烟气脱硫产业化方面取得的成绩和存在的问题 ,介绍了国际上烟气脱硫发展的基本情况