Optimization of strand and final electromagnetic stirrers of round bloom casters with multiple sections

Strand electromagnetic stirring (S-EMS) and final electromagnetic stirring (F-EMS) are the main methods used to improve the center porosity and segregation for round blooms. To optimize the stirring conditions, nail shooting tests were conducted for three sections of large round blooms with diameters of ?380 mm, ?450 mm, and ?600 mm. Acid leaching and sulfur print tests were used to investigate the shell thickness. Based on the results of nail shooting tests, a mathematical model of solidification was established, and the variation of shell thickness and the central solid fraction were exactly calculated by the model. By taking all sections into account, the locations of S-EMS and F-EMS were optimized for each section. In the results, the macro-segregation of various sections is improved after the locations of S-EMS and F-EMS systems are changed.     

Superior machinability of steel enhanced with BN and MnS particles

The strategy that replacing part of MnS with BN was proposed in order to decrease the sulfur content in sulfur based free-cutting steel. The effects of BN and MnS inclusions on the microstructure and machinability of the steel were systematically investigated. The results show that most of the BN and MnS inclusions exist individually in the steel and only a small amount of them are in a composite state forming either isolated particles or clusters of particles. In the case of multi-phased steel, the theoretical calculation predicts that the volume of large BN particles should be 0.7 times of the volume of large MnS particles. The machinability of this type of BN and MnS alloy steel over a wide range of cutting speeds ranging from a low speed appropriate for drilling to a high speed appropriate for turning is confirmed as being equal to or superior to that of an MnS reference steel, even though the sulfur content in the composite steel is only half that of the MnS steel. The aptitude for cutting effect of 240 ppm nitrogen and 115 ppm boron in the composite steel is demonstrated to be equivalent or even better than 1000 ppm sulfur in MnS free-cutting steel.     

考虑轴颈偏斜时滑动轴承的动力特性

本文建立了同时考虑轴颈径向位移和歪斜时的滑动轴承动力学模型.对于这种模型,油膜力将扩展为四个广义力分量.文章将相应的动力系数矩阵分解为对称和反对称两部分并讨论其物理性质.然后,本文推导得出该模型的正交变换矩阵,在此基础上导得各向同性的动力系数矩阵表达式,并讨论了诸元素的物理意义.文章最后引入动力系数椭圆的概念以分析非对称动力系数矩阵的变换性质.     

The orbital scale evolution of regional climate recorded in a long sediment core from Heqing, China

Based on the analysis of carbonate content and loss on ignition for a long sediment core (737 m in length) drilled in Heqing, the orbital scale evolution of the Southwest Monsoon is revealed, by using overlapped spectral analysis and filter methods. It is shown that the obliquity cycle and precession cycle are the key factors for the Southwest Monsoon evolution and that the change of the global ice volume and the uplift of the Qinghai-Tibetan Plateau also impose great influences on it.     

Metagenomic and functional analysis of hindgut microbiota of a wood-feeding higher termite

From the standpoints of both basic research and biotechnology, there is considerable interest in reaching a clearer understanding of the diversity of biological mechanisms employed during lignocellulose degradation. Globally, termites are an extremely successful group of wood-degrading organisms and are therefore important both for their roles in carbon turnover in the environment and as potential sources of biochemical catalysts for efforts aimed at converting wood into biofuels. Only recently have data supported any direct role for the symbiotic bacteria in the gut of the termite in cellulose and xylan hydrolysis. Here we use a metagenomic analysis of the bacterial community resident in the hindgut paunch of a wood-feeding 'higher' Nasutitermes species (which do not contain cellulose-fermenting protozoa) to show the presence of a large, diverse set of bacterial genes for cellulose and xylan hydrolysis. Many of these genes were expressed in vivo or had cellulase activity in vitro, and further analyses implicate spirochete and fibrobacter species in gut lignocellulose degradation. New insights into other important symbiotic functions including H2 metabolism, CO2-reductive acetogenesis and N2 fixation are also provided by this first system-wide gene analysis of a microbial community specialized towards plant lignocellulose degradation. Our results underscore how complex even a 1-microl environment can be.     

Comparison of reduction disintegration characteristics of TiO<Subscript>2</Subscript>-rich burdens prepared with sintering process and composite agglomeration process

To reveal the impact of the composite agglomeration process (CAP) on the reduction disintegration properties of TiO₂-rich ironmaking burden for a blast furnace, the reduction disintegration indices (RDIs), mineral constituents, and microstructure of the products prepared by the CAP and the traditional sintering process (TSP) were investigated. The results showed that, compared to the sinter with a basicity of 2.0 prepared by the TSP, the RDI_+6.3 and the RDI_+3.15 of the CAP product with the same basicity increased by 28.2wt% and 13.7wt%, respectively, whereas the RDI_-0.5 decreased by 2.7wt%. The analysis of the mineral constituents and microstructure of the products indicated that the decreasing titanohematite content decreased the volume expansion during reduction. Meanwhile, the decreasing perovskite content decreased its detrimental effect on the reduction disintegration properties. In addition, the higher silicoferrite of calcium and aluminum (SFCA) content improved the strength of the CAP product. Together, these factors result in an improvement of the RDI of the CAP products. In addition, compared to the sinter, the reduced CAP products clearly contained fewer cracks, which also led to mitigation of reduction disintegration.     

A novel process for comprehensive utilization of vanadium slag

Traditional processes for treating vanadium slag generate a huge volume of solid residue and a large amount of harmful gas, which cause serious environmental problems. In this study, a new process for the comprehensive utilization of vanadium slag was proposed, wherein zeolite A and a V₂O₅/TiO₂ system were synthesized. The structural properties of the as-synthesized zeolite A and the V₂O₅/TiO₂ system were characterized using various experimental techniques, including X-ray diffraction, X-ray fluorescence, scanning electron microscopy, and infrared spectroscopy. The results reveal that zeolite A and the V₂O₅/TiO₂ system are successfully obtained with high purity. The results of gas adsorption measurements indicate that the prepared zeolite A exhibits high selectivity for CO₂ over N₂ and is a candidate material for CO₂ capture from flue-gas streams.     

Medical entity and attributes extraction system based on relation annotation

The abundant entities and entity-attribute relations in medical websites are important data resources for medical research. However, the medical websites are usually characterized of storing entity and attribute values in different pages. To extract those data records efficiently, we propose an automatic extraction system which is related to entity and attribute relations (attributes and values) of separate storage. Our system includes following modules: (1) rich-information interactive annotation page rendering; (2) separate storage attribute relations annotating; (3) annotated relations for pattern generating and data records extracting. This paper presents the relations about the attributes which are stored in many pages by effective annotation, then generates rules for data records extraction. The experiments show that the system can not only complete attribute relations of separate storage extraction, but also be compatible with regular relation extraction, while maintaining high accuracy.