Flame characteristics of premixed H2-air mixtures explosion venting in a spherical container through a duct

The explosion venting duct can effectively reduce the hazard degree of a gas explosion and conduct the venting energy to the safe area. To investigate the flame quantitative propagation law of explosion venting with a duct, the effects of hydrogen fraction and explosion venting duct length on jet flame propagation characteristics of premixed H₂-air mixtures were analyzed through experiment and simulation. The experiment results under initial conditions of room temperature and 1 atm show that when hydrogen fraction was high enough, part of the unburned hydrogen was mixed with air again to reach an ignitable concentration, resulting in the secondary combustion was easier produced and the duration of the secondary flame increased. With the increase of venting duct length, the flame front distance and propagation velocity increased. Meanwhile, the spatial distribution of pressure field and temperature field, and the propagation process and mechanism of the flame venting with a duct were analyzed using FLUENT software. The variation of the pressure wave and the pressure reflection oscillation law in the explosion venting duct was captured. Therefore, in the industrial explosion venting design with a duct, the hazard caused by the coupling of venting pressure and venting flame under different fractions should be considered comprehensively.     

A study of the local site effects on the ground response for the city of Eskişehir,Turkey

Bulletin of Engineering Geology and the Environment - Local soil characteristics play a key role in determining soil-structure interaction and reliability of the superstructure behavior under...     

磷钨酸乙醇染色法在嗜铬颗粒电镜X射线显微分析中的应用

通过比较常规透射电镜制样法、快速冷冻固定－冷冻超薄切片法及磷钨酸乙醇（EPTA）染色法在嗜铬颗粒透射电镜X射线显微分析中的应用，发现磷钨酸乙醇染色法能使嗜铬颗粒电子着色，从而较好地显示嗜铬颗粒的超微结构。同时磷钨酸乙醇染色法也以在一定程度上原位保留生物样品中元素，可以应用于检测样品元素含量的变化或比较样品元素含量的组间差别，提示磷钨酸乙醇染色法是一种可应用于透射电镜X射线显微分析的经济简便的生物样品制备方法。     

一种制备磁性粉末的新技术--均匀颗粒成型法

采用均匀颗粒成型法（Uniform Dropler Spray-UDS）制备Fe基合金粉末，该方法制备的颗粒粒度分布均匀，性能一致，大大优于传统的粉末制备方法（如破碎法、气雾化），具有广阔的应用前景。本文分析了粉末制备过程中颗粒尺寸的影响因素，结果表明：颗粒的大小主要取决于坩埚底部小孔、坩埚内外气体压强差以及振荡频率三个独立变量。     

Topical use of aprotinin in open heart operations

Among various pharmacological agents used to reduce bleeding after open-heart operations, high-dose aprotinin therapy seems most promising. However, its long-term effects are still obscure; there is almost always possibility of bypass graft occlusions produced by the hypercoagulable state induced by aprotinin in coronary bypass operations. Topical application of aprotinin into the pericardial cavity could prevent the adverse effects. Fifty patients were prospectively studied to evaluate the effects of topical aprotinin. One million KIU of aprotinin was poured into the pericardial cavity before closure of the sternotomy in group 1 (n = 25). Patients in group 2 (n = 25) served as controls. Total postoperative bleeding was significantly reduced in group 1 when compared with that of group 2 (722.7 +/- 230.8 versus 1,282.6 +/- 225.7 mL; p < 0.01). The use of banked donor blood products was significantly less in group 1 than in group 2 (0.33 +/- 0.67 versus 1.36 +/- 0.86 units; p < 0.01). These results show that topical use of aprotinin reduces post-operative blood loss and need for transfusion. It seems promising and warrants further studies to be done.     

利用二进制数算法寻找5个点的Ramsey图

用二进制数来表示完全图的各种组合,借助计算机编程可从完全图的各种组合中寻找出ramsey图。5个顶点的Ramsey图是最基本的Ramsey图,这种基本方法为寻找更复杂的Ramsey图提供了基础。     

管式气体分散式反应器制备纳米碳酸钙

以石灰石为原料，利用管式气体分散式反应器新工艺制备出了粒径30～70nm的碳酸钙粉体。采用X射线衍射（XRD）、扫描电镜（SEM）、粒度分布仪及红外光谱仪（Fr-IR）等测试手段，对产品的物相、形貌和粒度分布进行了表征。X射线衍射表明产物为六方晶系方解石型碳酸钙并且产品结晶性能良好；扫描电镜及粒度分析表明粒度大小均匀、分散性良好；红外光谱表明改性后硬脂酸钠已吸附在碳酸钙表面，碳酸钙颗粒基本呈单分散状态。管式气体分散式反应器制备纳米碳酸钙粉体的优点是工艺简单，操作容易，原料易得，生产的产品粒径小，粒度分布窄，易于工业化生产。     

Effect of H2O adsorption on the electrical transport properties of double-walled carbon nanotubes

Water molecules adsorbed on a double-walled carbon nanotube (DWCNT) serve as charge trapping centers when present in low density and as electron donors when present in high density. There is a discontinuous change between the low- and high-density regions. H₂O molecules are apt to be adsorbed on the outer surface of DWCNTs, and in this case the electrical transport properties are extremely sensitive to environment, which suggests that DWCNTs are hole doped and act as an electric dipole with the inner tube.     

四川盆地海相页岩气富集条件及勘探开发有利区

历经十余年探索实践,四川盆地海相页岩气勘探取得了一系列进展,锁定五峰组—龙马溪组为最有利产层,提出了一批页岩气富集高产理论,形成了集地质评价、开发优化、优快钻井、体积压裂、工厂化作业、清洁开发等为一体的勘探开发技术,探明了万亿立方米级储量的页岩气大气田。时值中国页岩气勘探发展的重要节点,回顾四川盆地海相页岩气勘探开发历程、梳理五峰组—龙马溪组页岩气在地质条件与富集规律上的成果认识、展望四川盆地海相页岩气勘探的重点接替领域,对推进盆地海相页岩气的勘探开发有积极意义。(1)四川盆地海相页岩气勘探开发经历了4个阶段：评层选区找目标阶段;浅层至中—深层先导试验阶段;浅层至中—深层示范区建设阶段;浅层至中—深层上产、深层评价、常压页岩气评价、立体开发评价、超深层和新层系探索阶段。(2)四川盆地五峰组—龙马溪组的沉积条件优越,深水陆棚相高有机质含量页岩呈连续稳定分布;页岩气主要赋存在有机孔隙中,页岩储层在纵向上集中发育,连续厚度大;川南地区和川东南涪陵区块的构造相对简单,气源持续补给、远离古/今剥蚀区和大型断裂逸散区是页岩气富集保存的有利区;目前,五峰组—龙马溪组的页岩气资源量为33.19×10<...     

塔里木盆地塔中Ⅱ区奥陶系油气差异富集模式

针对塔里木盆地塔中Ⅱ区奥陶系油气多相态共存、产能差异和富集模式认识不清的问题,采用油藏地球化学方法分析了奥陶系流体性质、分布特征及成因。油藏pVT相态分析认为存在凝析气藏与轻质油藏沿走滑断裂共存的现象,原油的成熟度参数显示为成熟阶段的产物,天然气碳同位素和烃类比值揭示组分为原油伴生气和原油裂解气的混合,金刚烷化合物及天然气分析显示中寒武统盐下原油裂解气的充注是奥陶系凝析气藏形成的重要原因。结合高精度三维地震解释发现油气分布受到走滑断裂的控制,马尾、翼尾、走滑断裂带与逆冲断裂交汇部位具有较低的原油密度和含蜡量,以及较高的气/油比、干燥系数、4-MDBT/1-MDBT比值等,为油气充注的有利通道,走滑断裂周期性开启与膏盐层封堵机制耦合控制了塔中Ⅱ区奥陶系油气成藏。综合研究认为,塔中Ⅱ区油气具有侧生邻储、走滑断裂垂向输导、沿走滑断裂富集的特征,多期点状油气充注是造成奥陶系油气差异分布的重要原因。走滑断裂控制了奥陶系油气富集,马尾地堑、翼尾地堑、走滑断裂带与逆冲断裂交汇构造部位仍有较大的勘探潜力,中寒武统膏盐层下可能发育大规模气藏,需要进一步关注。