膜残余物会影响废水处理设备和排出水质量

本文介绍了使用膜处理水和废水的优点。焦点集中在系统产品水（透过液）一侧的优势。无论使用任何新技术或新应用，都会有优缺点。膜分离是一种非破坏性水处理技术。膜仅仅是使测流中的污染物浓缩。有几种类型的膜系统用于水和废水的处理。来自每种类型膜的测流含有不同浓度的污染物。这些未知的污染物对WWTP和收集系统有什么影响。     

Maximum a posteriori estimation of activation energies that control silicon self-diffusion

Self-diffusion in crystalline silicon is controlled by a network of elementary steps whose activation energies are important to know in a variety of applications in microelectronic fabrication. The present work employs maximum a posteriori (MAP) estimation to improve existing values for these activation energies, based on self-diffusion data collected at different values of the loss rates for interstitial atoms to the surface. Parameter sensitivity analysis shows that for high surface loss fluxes, the energy for exchange between an interstitial and the lattice plays the leading role in determining the shape of diffusion profiles. At low surface loss fluxes, the dissociation energy of large-atom clusters plays a more important role. Subsequent MAP analysis provides significantly improved values for these parameters.     

An Evaluation of Dissociated Ammonia and Hydrogen Atmospheres for Sintering Stainless Steel

The effect of sintering types 302, 302B, and 430 stainless steel powder compacts in hydrogen and dissociated ammonia was investigated. It was found that sintering in dissociated ammonia resulted in as much as 0.5 wt pet increase in the nitrogen content of stainless steel even though the dissociation of the gas was complete. Sintering in hydrogen, on the other hand, reduced the nitrogen content of the stainless steel to less than 0.01 wt pet. In the case of the 302-type stainless steel, the low nitrogen content resulted in a material that was largely ferritic, whereas the high nitrogen content rendered the material fully austenitic. Sintering in dissociated ammonia resulted in lower density, generally lower tensile strength, less ductility, and higher hardness than sintering under equivalent conditions in hydrogen. The reduction of oxides on both stainless steel and iron particles was found to be effected by hydrogen partial pressure in the sintering atmosphere. Compacting pressure was found also to effect oxide reduction during sintering.     

Editorial: Journal of Scheduling (2022)

Journal of Scheduling -     

An energy approach for predicting springback of metal sheets after double-curvature forming, Part I: axisymmetric stamping

In our previous study (Xue P, Yu TX, Shu E. International Journal of Materials Processing Technology 1999; 89-90:65-71.), based on the membrane theory of shells of revolution and an energy method a mechanics model and corresponding analytical procedure have been proposed to predict springback of circular and square metal sheets after a double-curvature forming operation. The strain hardening of the material is incorporated into the mechanics model. In the present paper, the method is extended to the cases, in which bending effect, as well as bending-and-unbending effect are taken into account. It is shown that the procedure developed is capable of quantitatively predicting the strain distribution and springback of metal sheets after axisymmetric stamping with a relatively minor effort of calculation and a good accuracy. The effect of stretching force applied at the edge of the plate on springback is also considered. Excellent agreement is found between the theoretical prediction of springback and experiment results.     

Polymer–leather composites. III. Morphology and water absorptivities of selected acrylic polymer–leather composite materials

The morphology of composite materials made by polymerizing methyl methacrylate into chrome-tanned cattlehide was examined by both light and scanning electron microscopy. The composites were selected from a series previously prepared and characterized, and their kinetics were reported. Micrographs of the polymer phase of the composites, prepared by preferential removal of collageneous material with 6N hydrochloric acid, yielded negative replicas of the fiber conformations. These provided evidence in support of proposed mechanisms of polymer deposition for two different methods of composite preparation. One method involved emulsion polymerization of monomer into hydrated leather and the other, preferentially filling leather free space. Both light and scanning electron microscopy of all composites and replicas revealed poly(methyl methacrylate) deposited largely in coarse aggregates around individual fibers. In emulsion systems, fiber bundles expanded with continuous deposition. No difference was observed in the morphology of bound and deposited polymers. However, high magnification of bound-polymer replicas exposed polymer surrounding some fibril traces. Deposition of polymer in the fine structure of bulk or solution prepared composites was not found; instead, all free space was occupied. A theory specifying polymer location in previous publications of this series, and extended here to define replica parameters, was abundantly supported by measured physical properties. A dominant grafting mechanism was precluded because the large domains limited points of possible attachment. Water absorptivities of emulsion prepared composites and controls were identical when the data were corrected to neat leather, although the rates were slightly perturbed. In contrast, both rate and equilibrium absorption data of the bulk and solution composites were retarded by polymer presence.     

Meß- und Regeltechnik in Chemieanlagen unter sicherheitstechnischen Aspekten

Safety aspects of control engineering. The influence of control engineering on the safety of chemical plant is described. Particular attention is paid to demands placed on control engineering equipment from a safety viewpoint and to their adjustment, arrangement, and link-up. It is shown that, under certain circumstances, control engineering equipment can be used instead of conventional safety equipment, while preserving the same degree of safety. Considerations are also presented as to effective testing procedures and reasonable testing intervals. These ideas are preceded by some fundamental safety concepts relating to the planning of chemical plant.