Assessment of Bitumen Re c overy from the Athabasca Oil Sands Using a Laboratory Denver Flotation Cell

A methodology was developed in this study to evaluate the effect of operating parameters on the processability of oil sands using small‐scale laboratory experimental devices. By subtracting bitumen recovered to the froth by entrainment with water, the concept of “true flotation recovery” is proposed to describe bitumen recovery resulting from bitumenbubble attachment. The experimental results indicated that “true flotation recovery” is a more sensitive and meaningful marker than overall bitumen recovery to evaluate the processability of oil sands using small‐scale laboratory test units.     

基于匹配策略融合的低误差快速图像拼接算法

针对目前多数拼接算法正确匹配率低、耗时及误差大的问题,提出了基于匹配策略融合的改进图像拼接算法。该算法首先仅在图像的重合区域提取SIFT特征点,并计算SURF特征描述符;其次,融合改进的最近邻比次近邻、双向交叉检查及匹配差值的阈值化3种匹配策略,结合坐标约束及RANSAC算法完成特征匹配;最后,提出利用配准参数计算任意图像到参考图像坐标空间的投影变换模型的方法,并利用多线程技术将所有图像投影至参考坐标系,经过亮度校正、加权融合后合成全景图。实验结果表明,提出的拼接算法正确匹配率提高了10~20%,拼接总耗时约为传统逐帧扩大式拼接算法的1/3,且累计误差大大降低,拼接图像畸变小。     

Reaction pathway of benzonitrile formation during toluene ammoxidation on vanadium phosphate catalysts

The reaction pathway of the ammoxidation of toluene on (VO)₂P₂O₇ used as catalyst and the interaction of potential intermediates with the pyrophosphate were studied by spectroscopic techniques (FTIR, EPR), temperature-programmed chemisorptions/ reactions (TPD, TPRS) and transient studies such as the temporal analysis of products (TAP) technique. NH₃ is chemisorbed on the catalyst surface, forming three different species, i.e., NH ₄ ⁺ ions located on BrØnsted sites, coordinatively bound NH₃ on Lewis sites and NH ₂ ^– groups, presumably P-NH₂. Toluene that is probably adsorbed on Lewis sites reacts in a first step to a benzyl radical. A subsequent partial oxidation by interaction of V^IV=O groups generates a V...O=CH-C₆H₅ surface structure. This benzaldehyde-like surface species reacts with adsorbed NH₃ according to a Langmuir-Hinshelwood mechanism. TAP experiments on ammonium-containing vanadium phosphates revealed that NH ₄ ⁺ ions could act as potential N-insertion species. No formation of benzylamine as well as the generation of V=NH surface groups as possible intermediates or N-insertion sites were observed.     

氟树脂性能与加工应用(续10)

介绍了聚四氟乙烯悬浮树脂成型加工有关的物理性能,树脂的成型加工及选用方法.分别叙述了模压成型、自动模压成型和液压成型的原理、过程及设备.     

2.5万t／aBR后处理机电设备成套技术

针对原１．５万ｔ／ａ ＢＲ后处理存在的问题，选定了主物料的工艺流程，按照生产需要开发试制了后处理专用机械设备，并介绍了在新建的生产线上的投用的１５种机电设备的主要特性。三年多的生产实践证明，该生产线运行良好，收到了显著的经济效益和社会效益。由此形成的后处理机电设备成套技术在国内居领先地位，有很好的推广应用价值。     

Shear rates investigation in a scraped surface heat exchanger

The electrodiffusion technique was performed in order to investigate the shear rate on a scraped surface heat exchanger. Microelectrodes were placed inside: the walls of the outer cylinder; the inlet and outlet bowls; the rotor and the blades. Highly viscous Newtonian fluid (Emkarox HV45 solutions) and non-Newtonian model fluid (aqueous solutions of CMC) were used. The electrodiffusion method allowed us to measure wall shear rates. Maximum shear rate was observed at the scraping surface and caused by blades scraping, high shear rate was also measured on the leading edge of the blades. In the other parts of the exchanger, shear rate remained low but the development of Taylor vortices completely modified the scraped surface heat exchangers behaviour inside the surface of the bowls. A dimensionless representation of the friction factor was established for the inner and outer wall surface of the exchanger.     

Electrochemistry at capped platinum nanoparticle Langmuir Blodgett films: A study of the influence of platinum amount and of number of LB layers

Platinum nanoparticles (n-Pt), over-grafted with 2-thiophenecarbonyl chloride are assembled on gold electrodes, by the Langmuir Blodgett (LB) technique using behenic acid (BHA) as promoting agent. These layers are electrochemically active without any preliminary activation. The [Fe(CN)₆]^3−/4− redox couple was used as electrochemical probe. This paper reports on the influence of the number of deposited LB layers, and the n-Pt density on the electrochemical response. n-Pt density was modified by the change of the “BHA/n-Pt” ratio. Cyclic voltammograms of “[Fe(CN)₆]^3−/4−” were observed whatever the coating conditions. As soon as the first layer was deposited the electrochemical response was associated to the n-Pt coverage, its response slightly increased up to a steady state for five or seven layers. As expected, the increase of the Pt density favored the increase of the current density. XPS analysis performed before and after electrochemical cycling showed that 4-mercaptoaniline capped platinum nanoparticles, and their over grafting were chemically and electrochemically stable. Analysis of influence of the number or the n-Pt density of the layers showed that the electrochemically active part of LB electrodes was provided by the last layer plus a part of the underlying one.     

纳米复相陶瓷材料的烧结技术

纳米复相陶瓷的烧结与普通陶瓷的烧结不同，在纳米复相陶瓷的烧结过程中需要采取相应的措施尽可能地控制晶粒的长大。目前，国内外研究者主要是通过改进传统烧结技术或采用新型烧结技术烧结制备纳米复相陶瓷。文章综述了目前国内外用的比较多的几种制备纳米复相陶瓷的烧结技术，并对其特点和应用情况进行了总结。     

浅析超细碳酸钙的几项主要指标

根据对超细碳酸钙制备研究和应用推广试验的体会和经验，阐述了对超细碳酸钙粒径、晶形、比表面积、吸油值、主含量等几项指标的认识，指出超细碳酸钙的重点发展方向是专用化、系列化、多品种化、功能化。应根据用途的不同，对粒径大小、晶体形状、比表面积、吸油值、主含量等提出具有针对性、各具特色的要求。     

取代基及分子量对非离子型纤维素醚表面特性的影响

根据Washburn的浸渍理论(Penetration Theory)和van Oss-Good- Chaudhury的组合理论(Combining Theory)及应用柱状灯芯技术(Column Wicking Technique),对几种非离子型纤维素醚,如甲基纤维素、羟丙基纤维素和羟丙基甲基纤维素的表面特性进行了测试。由于这些纤维素醚的取代基、取代度和分子量不同,所以它们的表面能及其组成部分有着明显的差异。数据说明,非离子型纤维素醚Lewis碱大于Lewis酸,表面自由能的主要成分是Lifshitz-van der Waals力。羟丙基的表面能及其成分都大于羟甲基。而在相同取代基和取代度的前提下,羟丙基纤维素的表面自由能正比于分子量;而羟丙基甲基纤维素的表面自由能则正比于取代度,反比于分子量。实验还发现非离子型纤维素醚中的取代基羟丙基和羟丙基甲基的表面能似乎都大于纤维素的表面能,而实验证明所测试得出的纤维素的表面能及其成分的数据是与文献所吻合的。