Effect of level of overflow solid outlet on pressure drop of a bubbling fluidized-bed

The effect of level of the overflow outlet for continuous flow of solid particles on the pressure drop of a bubbling fluidized-bed that employed an in-bed inlet for solid feed was investigated with changing solid properties, solid feed rate, gas velocity, and level of the overflow outlet. The pressure drop of fluidized-bed (Δp_bed,f) decreased with increasing gas velocity, but increased with either solid feed rate or level of the overflow solid outlet (L). The Δp_bed,f/L increased with L. Irrespective of particle size and density, bed height converted for minimum fluidization condition (pressure head by bed weight, H_mf,f) decreased with increasing the volume flow rate of bubble but increased with either the solid feed rate or the level of the overflow solid outlet. The nominal vertical height, height between the H_mf,f and the level of the overflow outlet, that bubbles transported particles while drawing the solid particles out of the fluidized-bed increased as either the volume flow rate of bubble or level of the overflow outlet increased. However, it decreased as the solid feed rate increased. It appeared that the power of bubble for lifting solid to be discharged through the overflow outlet was same at the fixed volume flow rate of bubble, solid feed rate, and level of the overflow solid exit. The power of bubble increased with the level of the overflow outlet but not linearly. The correlation proposed for the pressure drop across the bubbling fluidized-bed was useful to predict the pressure drop across the recycle chamber of the loop seal and the external solid circulation rate in the circulating fluidized-bed system.     

盘道岭隧洞除险加固工程糙率原型观测及过流能力分析

盘道岭隧洞为长距离无压隧洞(长15.723 km),因地层岩性复杂、地质条件恶劣,出现了裂缝、表面混凝土剥蚀、地下水外渗等安全隐患。于2013年9月实施了除险加固,在洞壁套衬了最小衬砌厚度为0.25 m的钢筋混凝土,减小了隧洞过水断面。加固后隧洞表面较原隧洞光滑,糙率有所减小。隧洞过流能力能否满足设计要求,糙率是关键,常规计算及试验难以满足精度要求,为此进行了原型观测。介绍了糙率原型观测的理论依据、观测手段及方法,并对各段观测糙率的合理性及泄流能力进行了分析。观测分析表明:疙瘩沟矩形明渠段、隧洞进口未加固段、隧洞进口加固段和隧洞出口加固段的糙率分别为0.013 07,0.015 49,0.011 16,0.010 52,结合观测断面内的水位测定值,分析得出盘道岭隧洞经除险加固后过流能力满足设计要求。观测成果可为类似引调水工程优化设计、节约工程投资提供科学依据。     

SSRC:source rate control algorithm for delay-sensitive flow in data center network

Previous work had studied how to ensure the transmission time of delay-sensitive flows,but falled short in its effectiveness for a given period.Motivated by that and based on SDN/OpenFlow framework,a SDN-based source rate control (SSRC) algorithm was proposed.With a global view of network,SSRC can quickly locate the potential congestion node,adjust the transmission rate of source and reduce the response time of SSRC.The experiment results show that compared with DCTCP and other algorithms,SSRC can shorten the completion time of flows by 75% in average,which can ensure the transmission time of delay-sensitive and solve the problem of Incast well.     

某导弹系统随动异常机理分析与解决

为排查和解决导弹系统大角度随动发生摆动的现象,从理论分析和计算中发现发射装置在大角度随动控制时,由于本身软硬件设计约束,控制算法溢出,会导致导引头随动异常.通过对发射装置软件控制算法采用压缩法处理后,导引头随动正常.经试验论证,此故障原因定位准确,改进设计方法有效,满足系统大角度随动要求.     

底孔溢流堰设计与施工的几个关键技术探讨

本文探讨了浯溪口水利枢纽工程底孔溢流堰设计与施工中所采取几个的关键技术;其中基于物理模型试验进行底孔溢流堰设计。模型试验结果表明底孔溢流堰设计既能保证水流平顺,过流能力大,又能保证不出现导致堰面发生破坏的堰面负压。此外,底孔溢流堰施工通过采用倒弧面模板和混凝土分区等工程措施可保证堰体混凝土满足强度、抗冲、温控以及平整度等要求。这些技术可为类似工程溢流堰设计与施工提供重要参考。     

基于总势能极小原理的渗流溢出点位置计算方法

在考虑渗流影响的工程中,自由面的计算是渗流计算的主要内容,精确确定溢出点位置是准确计算自由面的关键。基于总势能极小原理的渗流溢出点位置计算方法,是在溢出点位置调整的过程中,通过寻找全域总势能的极小值确定溢出点位置的一种方法。通过算例分析,得出如下结论：基于总势能极小原理的渗流溢出点位置计算方法弥补了先前溢出点计算方法精度低、需迭代计算、不易收敛的缺点,精确、高效地计算出溢出点位置。     

加格达奇东小河地下水溢流积冰影响因素

黑龙江省大兴安岭地区的加格达奇区属于典型的高纬度寒区,是我国地下水溢流积冰问题最严重的地区之一。东小河位于加格达奇市区东部,是区域溢流积冰现象的代表性区域。采用实地踏勘和水文地质物探等方法,分析了该地区溢流积冰现象形成三个阶段及其特征,特别是气象因素、流域下垫面因素、冻土层因素的影响,指出加格达奇区流域下垫面因素中的浅薄含水层和冻土层因素是该地区独特的溢流积冰现象形成的关键因素。     

冻土条件下均质土堤漫顶溃决试验研究

为了研究冻土条件下的溃堤机理,开展了弯道水槽概化模型试验。基于结构光的三维成像原理,提出了一种无干扰全方位的实时溃口三维参数测量方法,并结合温度传感器监测堤内温度变化,研究了冻土条件下均质土堤漫顶溃决过程中溃口形态的演变规律和溃决区域的水位、流速、流量变化特性。依据试验中溃口冲蚀特点,将溃堤过程划分为渗透过流、堤后冲蚀、横向展宽、冲淤平衡4个阶段,黏性土堤和非黏性土堤第2阶段、第3阶段分别以陡坎冲蚀和失稳坍塌为主要特征,且黏性土堤会出现明显的陡坎合并现象。试验结果还表明:冻结后土体间隙的冰晶体与土颗粒相互胶结,土体的黏聚力增大,溃口扩展速率及溃决区域的水位、流速变化率均减小,且黏性土堤受冻土深度的影响更加明显;冻土条件下堤防背水侧与堤顶的连接处薄弱易溃,应加强维护,且一旦溃堤应优先对临水侧进行封堵。     

发展中国家与地区企业组织演化：一个解释框架

与发达国家及地区的企业相比较,发展中国家及地区企业面临的市场条件、宏观政策环境、体制约束与所要解决的利益冲突均存在着自身的特点,在企业组织形态、演化动力、演化机制及途径等方面存在着自身的一系列复杂性与特殊性,考虑到发达国家及地区的企业组织形式演化的历史实践以及俄罗斯、东欧等地快速私有化的教训,在企业组织演化的进程中,发展中国家与地区不能照搬发达地区的企业组织模式,而是必须结合本国的经济体制、制度特征及经济发展战略进行有效的自主创新。     

一种基于fuzzing技术的漏洞发掘新思路*

目前检测软件缓冲区溢出漏洞仅局限于手工分析、二进制补丁比较及fuzzing技术等,这些技术要么对人工分析依赖程度高,要么盲目性太大,致使漏洞发掘效率极为低下。结合fuzzing技术、数据流动态分析技术以及异常自动分析技术等,提出一种新的缓冲区溢出漏洞发掘思路。新思路克服了已有缓冲区溢出漏洞发掘技术的缺点,能有效发掘网络服务器软件中潜在的未知安全漏洞（0day）,提高了缓冲区溢出漏洞发掘效率和自动化程度。