Continuously Conducted Selective Hydrogenation of Benzene to Cyclohexene in a Four‐Phase System

Currently, the production of nylon 6 and nylon 6.6 is based on the complete hydrogenation of benzene to cyclohexane over nickel or platinum catalysts and its subsequent oxidation at very low conversions to a mixture of cyclohexanol/cyclohexanone. This mixture is further reacted to ?‐caprolactam or adipic acid. Alternatively, the reaction can be carried out by selective hydrogenation of benzene to cyclohexene and subsequent hydration with acidic catalysts to cyclohexanol. A laboratory method for the selective hydrogenation of benzene in a continuous stirred‐tank reactor (CSTR) using a gas/liquid/liquid/solid system is presented.     

Catalytic performance of a copper–promoted CeO2 catalyst in the CO oxidation: Influence of the operating variables and kinetic study

A study of the CO oxidation reaction was conducted on a CuO–CeO₂ catalyst, with a copper content of 20 at%. The stability, activity and selectivity of this sample were evaluated in the absence of H₂ and also under PROX conditions (i.e. in great H₂ excess). The influence of the reaction temperature and the feed composition was also analyzed. It was found that water and CO₂ have a negative effect on the catalytic activity. Except for the undesired oxidation of hydrogen, the occurrence of other lateral reactions that could be present in the PROX reactor can be discarded. A kinetic study was carried out in order to fit a classical power-law expression for CO oxidation rate. Although this mathematical expression gave a good fit in limited concentration ranges, it was found that the partial reaction orders depend on the reactant molar fractions.     

我看中国物流行业

中国需要成为全球物流供应链的一部分,这方面正面临越来越大的压力.在很多情况下,供应链起始于制造业地区,随着现代化通信技术和信息技术解决方案的出现,供应链变得全球化,响应速度越来越快.快速响应的供应链要求短时间的市场周转期.面对国外的快速供应链,中国各个行业还有多长时间维持低制造成本与长周转期之间的平衡呢?竞争并不只是公司之间,还存在于供应链之间.企业内部物流管理和整体供应链管理之间最大的不同,是前者只是指公司内部,而后者包括很多不同的公司.中国市场需要的是面向起始于复杂而绵长的供应链的一体化物流服务.     

Sicherheitstechnik im Wandel?

Ohne Zusammenfassung     

Direct Calibration by Fitting of Cuboids to a Single Image Using Differential Evolution

In this article we propose a new method to calibrate directly the camera by which it was taken an image of a cuboid, and to find at the same time the orientation and side lengths of the cuboid. This is a highly non-linear optimization problem that is solved directly using a heuristic called differential evolution. We show in this paper that this problem is very difficult if one tries to solve it with a conventional scalar optimization procedure. Although differential evolution is a heuristic, we find valid results in 100% of the executions. We test our method with synthetic and real images.     

Modeling of texture evolution in the deformation zone of second-phase particles

Cast aluminum alloys usually contain coarse constituents which are likely to serve as potential nucleation sites during recrystallization. In the course of deformation a special zone develops around such non-deformable particles, which is characterized by a high local strain and high misorientation gradient. This makes them preferred nucleation sites for recrystallization during a subsequent heat treatment. The orientations of such nucleation sites are of importance for the recrystallization textures. The aim of this study was to investigate the evolution of the microtexture within the deformation zone. For plane strain compression the strain distribution around particles was modeled by means of the finite element method (FEM). For spherical and cuboidal particles the local displacement gradients were used to compute the deformation texture by a Taylor type model. The predicted textures were compared to published experimental data.     

Cover Picture: Microstructural Comparison of Conventional and Microwave Sintered BaTiO3 (Adv. Eng. Mater. 5/2007)

The cover sheet shows thermally etched fractured cross‐sections of conventional and microwave sintered BaTiO₃. Microwave sintering has a profound effect on the microstructure. Sintering starts earlier and the Curie temperature is influenced. More details can be found in the article by A. Dorner‐Reisel on page 400.     

Neue Entwicklungen bei Überströmstrecken von Dämmen

The experiments conducted to date at the TU Vienna’s Hydraulic Laboratory, some of which involved classic construction methods for revetments and alternative constructions, should be used as a foundation, contributing to their optimization and continuing technical/commercial evolution. The construction solutions already explored will need to be developed further so as to accommodate steeper bank angles and specific hydraulic strains; this will allow them to be serve as a broad basis for planning engineers and help to ensure the safety of overflow sections.