Nb和时效时间对热轧中锰TRIP钢中P偏聚的影响

热轧态中锰TRIP钢首先经650 ℃退火2 h,随后在550 ℃进行等温时效热处理,采用场发射扫描电镜(FE-SEM)研究该钢中P的偏聚和时效析出行为的变化情况。结果表明,中锰TRIP钢中P在晶界的偏聚是一种非平衡偏聚现象,临界时间约为50 h,与理论计算结果48 h较为吻合。在局部偏聚区域内,C与P存在共偏聚的关系,即P偏聚量高的地方,C含量也高。而合金元素Nb具有抑制P偏聚的效果,在20~70 h时效时间内,可以相对降低6.57%~19.5%的最大P偏聚量。根据电子背散射衍射(EBSD)菊池线分析,P偏聚量低于2.28at%时,P为固溶状态,高于2.28at.%时,P为析出状态。     

基于修正幂律模型流体的柳叶形扶正器旋流规律及应用

为提高注水泥过程中水泥浆顶替效率，国内外愈来愈多地使用旋流扶正器。但是，目前旋流扶正器结构参数主要靠经验设计，缺乏理论基础也没有相关行业标准。针对依据文丘里效应设计的柳叶形旋流扶正器，基于修正幂律流体模型，构建了旋流扶正器旋流长度计算模型。通过数值模拟对旋流扶正器井下旋流规律进行研究，推导出了旋流扶正器在修正幂律流体条件下，周向平均速度和完全顶替的临界速度公式。基于旋流扶正器井下旋流规律，分析了井眼环空结构、流体性能、井下井壁附着力对水泥浆顶替效率的影响，优化了柳叶形旋流扶正器旋流角、扶正棱长度、扶正棱有效体积和扶正器高度等设计参数。对比分析了柳叶形与常规旋流扶正器在不同工况下的旋流长度，柳叶形扶正器的旋流长度比常规扇形平均提升了32%，比常规梯形扶正器平均提升了47%。柳叶形扶正器在新疆顺北油田顺北3井等20多井次超深井应用，应用井固井质量明显优于常规扇形的旋流扶正器。     

Safe preparation of beefy meaty peptide with Bacillus subtilis

Preparation of flavour peptides with microorganisms is an attractive choice for its large-scale production. However, beefy meaty peptide (BMP), as a research hotspot in the field of umami peptide, has been studied in few microorganisms, and furthermore, the safe preparation of BMP has not yet been reported. In this study, multi-copy BMP (8BMP) was successfully expressed and produced in the ‘generally recognized as safe’ Bacillus subtilis (B. subtilis). Firstly, 8BMP with the potentially intense umami was screened out based on molecular docking analysis. Then, it was successfully expressed in the B. subtilis 168 and verified through sensory evaluation. Finally, the scaling capacity of 8BMP was evaluated in a 5-L fermenter, with the highest yield (0.84 g L⁻¹) 6.4 times than that of shake flask, which is conductive for industrial production of BMP and other food peptides.     

一个北方乡村寺庙的千年自传(下):平顺龙门寺石刻文辑录(17~20世纪)

山西平顺龙门寺留有大量五代至民国的石碑、塔幢、题记,学界至今未有完备的整理及录文发表。笔者经多次实地踏查及文献搜集,整理、辑录了66篇(处)记文,是迄今对龙门寺文字史料最为完整的辑录。本篇为明崇祯、清、民国时期的部分,共计32篇。     

Investigation of the grinding temperature and energy partition during cylindrical grinding

In this study, the distribution of temperature and energy under the process parameter conditions and thermal physical parameters are investigated using a physics-based model via the finite element modeling (FEM) simulation and experimental validation during cylindrical grinding. A cylindrical grinding model is modeled to simulate the chip removal behavior in the grinding process and to measure the workpiece and chip temperatures by refining the temperature field. Workpiece speed affects the energy partition into chip more obviously than other grinding parameters. Reasonable selection of grinding parameters greatly reduces the energy partition into the workpiece from 80% to 50–30% or even lower. This study offers a comprehensive understanding of heating mechanisms during grinding and thus is very beneficial for process optimization.     

Scalable fabrication of novel SiC nanowire nonwoven fabric

Flexible papers constructed by one-dimensional nanowires have attracted much attention due to their various applications. Herein, a novel nonwoven fabric with paper-like qualities composed of zinc blende SiC (β-SiC) nanowires was fabricated by a scalable rolling process. The SiC nanowires were synthesized by the carbothermal reduction reaction of the carbon fiber and carbonaceous silica xerogel. The crystal phase, morphology and microscopic structure of the as-prepared SiC nanowires were characterized by field emission scanning electron microscope, X-ray diffraction and high-resolution transmission electron microscopy. The nanowire vapor–solid growth mechanism and preparation process for SiC nanowire nonwoven fabric were also discussed. The freestanding SiC nanowire nonwoven fabric exhibited high flexibility, high mechanical strength, excellent refractory performance and thermal stability. With high flexibility, high mechanical strength, superior nonflammability and thermal stability, the flexible paper-like 3C-SiC nanowire nonwoven fabric materials would be expected to have some potential applications, such as ceramic matrix composites, metal matrix composites, energy storage, catalyst supports, radiation-proof fabric, filtration and separation.     

渤海湾盆地沙垒田地区新近纪走滑断裂发育特征及其对油气富集的控制作用

沙垒田凸起地区是渤海海域西部新近系油气最为富集的区域，为了明确新近系走滑断裂发育特征及对油气富集的控制作用，依托连片高精度三维地震、钻井取心等资料，对走滑断裂类型及发育特征进行了详细刻画，并对走滑断裂与成藏要素之间的关系进行了探讨。综合研究表明：研究区发育断穿基底走滑断裂、盖层走滑断裂及伸展-走滑断裂三种不同类型走滑断裂；走滑断裂对圈闭的控制作用表现为在不同类型走滑断裂控制下，断裂带内及断裂带间形成了多种类型圈闭，其中大型披覆背斜圈闭、断鼻、断背斜圈闭为有利圈闭，小型断块圈闭为不利圈闭；走滑断裂对输导体系的控制作用体现在断裂活动控制了骨架砂体输导体系及断裂输导体系的形成发育，有利于周边凹陷成熟烃源岩排烃及运移输导；走滑断裂对储层的控制作用表现为走滑作用形成的高角度裂缝提高了储层渗透率，改善了储层物性。新近纪普遍发育的走滑断裂是研究区油气富集的主控因素。     

Secrecy Outage Performance Analysis of DF Cognitive Relay Network With Co-channel Interference

Wireless Personal Communications - In this paper, we investigate the secrecy outage performance of the decode-and-forward cognitive relay network with the existence of the co-channel interference,...     

In Situ Investigation and Numerical Simulation of the Failure Depth of an Inclined Coal Seam Floor: A Case Study

Mine Water and the Environment - The 1131 working face of the Yangcheng coal mine was used for a research demonstration to study the failure characteristics of an inclined coal seam floor. A...     

A dynamic SVR–ARMA model with improved fruit fly algorithm for the nonlinear fiber stretching process

Natural Computing - The fiber stretching process plays the key role in the process of fiber production and its effects is measured by the stretching ratio. The stretching ratio is determined by the...