超大直径扩底嵌岩桩模型试验研究

为了弥补因现有技术无法对深圳平安大厦进行现场试桩分析的不足,研究超大直径桩的桩身承载及沉降规律,采用缩尺模型试验的方法对其进行了研究。研究结果表明:超大直径嵌岩桩桩身最大承载力远高于规范计算得到的竖向抗压承载力特征值,其上部荷载主要由桩端承担,对桩进行扩底处理后桩端承载所占总荷载比例较等直径桩更大,且等直径嵌岩桩的侧摩阻力比扩底嵌岩桩的侧摩阻力的发挥更显著。桩身在中风化—微风化花岗岩段的侧摩阻力在设计中均不应忽略。现场实测结果对比验证了模型试验结果的合理性。     

Subcutaneous Arteriolar Vasomotion Changes During and After ELF-EMF Exposure in Mice in Vivo

Summary Biological effects of extremely low-frequency electromagnetic fields (ELF-EMF) on microcirculation were investigated in vivo by monitoring arteriole diameters in conscious mice. Measurements of blood vessel diameter were monitored 33 min non-stop before during and after exposure with ELF-EMF and every 389 ms blood vessel diameter were calculated. Using a dorsal skinfold chamber (DSC), and following caudal vein injection of FITC-dextran 250 kDa, the microvasculature (initial arteriole diameter of 45–80 μm), was examined by intravital microscopy and video images were recorded for a total time of 33 min. Arteriole diameter was continuously measured by on-line analysis using a High-speed Digital Machine Vision System CV-2100, using an edge-gap detection algorithm. Since vessel diameters exhibit rhythmic variation expressed by vasomotion, for estimation of microcirculatory activity we used both raw data for frequency analysis of vasomotion (measured frequencies of vasomotion were in the range 0.008÷0.1 Hz) and evaluate mean blood vessel diameter for each 1 min period of time, and make a comparison between Pre, Exposure/Sham exposure and Post exposure periods, with the aim to evaluate possible changes in mean blood vessel diameter as a result of ELF-EMF action. During EMF exposure and post-exposure periods, arteriole diameters increased significantly compared with the pre-exposure period, and the changes were larger during post-exposure. In contrast to sham exposure, vasodilatation of the microvasculature was significantly greater during exposure and post-exposure to 16 Hz EMF. These findings suggest that ELF-EMF may have potential therapeutic use benefit for treating vascular disorders.     

Minimum propagation diameter and thickness of high explosives

The critical diameter and critical thickness of two heterogeneous explosives were measured experimentally. By comparing these experimentally determined values of critical diameter and critical thickness, the role of front curvature in the failure of the detonation can be investigated. Current theories of detonation based on front curvature would predict the critical diameter should be twice the critical thickness. Experimentally, the expected two-to-one ratio was only validated for the case of a heterogeneous explosive with very fine scale heterogeneities. The ratios of critical diameter to critical thickness (for the two selected explosives) are also compared to previously measured values for homogeneous (liquid) explosives in order to contrast the dominant failure mechanism in these different explosives.     

空腔及其耦合水袋抑制瓦斯爆炸实验研究

为探索一种新型瓦斯抑爆技术,设计宽径比分别为1.5,2.5,4的矩形空腔体,并基于自行搭建的长36 m,管径为200 mm的大型瓦斯爆炸实验系统,通过在管网中铺设不同宽径比空腔体结构开展抑爆实验。此外依托支护简单的宽径比为2.5的空腔体,在腔体内填充不同质量水袋开展实验,以期进一步提高空腔体抑爆性能。结果表明:对于长径比为2.5、高径比为1的空腔体在实验宽径比范围内均能在一定程度上抑制瓦斯爆炸强度;随着腔体宽径比的增加,截面面积变化率增大,火焰及冲击波超压峰值衰减幅度越大,抑爆效果越佳;空腔耦合抑爆剂水能提高腔体的抑爆效果,在实验范围内较纯空腔可使火焰抑制率最大提高70%,超压峰值抑制率最大提高263%。     

港口机械用大直径滑轮坯的轧制

介绍了大直径滑轮坯的轧制工艺 ,分析了轧制过程中存在的问题 ,并提出了解决方法。     

GJB 150.8A淋雨试验解读及淋雨试验探讨

对自然界中云滴到雨滴的转化和降雨的形成过程进行了阐述,同时对降雨过程中雨滴的形状、直径、降雨强度、终速度等的物性特点进行了分析.重点探讨了人工模拟降雨试验方法中关于雨滴直径0.5～4.5 mm、雨滴终速度9 m/s、行程、风速18 m/s等指标要求在实际试验中涉及的部分相关问题,基于对降雨过程和降雨引起的破坏机理的分析,结合淋雨设备原理和国内环境试验设备厂家现状,对现行GJB 150.8A—2009淋雨试验中的雨滴直径、雨滴终速度提出了补充完善的建议和意见.     

三丁基锡对中国近海主要优势浮游植物的毒性作用研究

研究三丁基锡（TBT）对我国近海优势浮游植物丹麦细柱藻（Leptocylindru danicus）、玛氏骨条藻（Skeletonema marinoi）、日本星杆藻（Asterionella japonica）、派格棍形藻（Bacilaria paxillifera）、柔弱角毛藻（Chaetoceros debili...     

塔里木盆地气溶胶粒度分布研究

使用Series 210收集了塔里木盆地内6个不同地点的气溶胶,获取了该地区气溶胶的粒度分布,并计算了对应的气溶胶数量中位直径。研究发现:在自然情况下,气溶胶分布遵循双峰分布的规律,其中第一峰值通常出现在0.5μm附近,第二峰值出现在3μm附近;由于采样点的气象条件、地表情况等差异所致,不同采样地点的峰位和峰面积有一定的差异;各采样点气溶胶分布规律显示,绝大多数气溶胶粒子粒径小于1μm。自然条件下,大多数采样点气溶胶粒子数量中位直径小于1μm。     

基于新型反应器的好氧颗粒污泥的稳定性控制

为避免好氧颗粒污泥随着粒径和密度的变化屡次出现其稳定性失去控制,导致好氧颗粒污泥系统运行失败的状况发生,开发了一种新型反应器能够很好地控制好氧颗粒污泥的粒径和密度.新反应器结合旋流器的使用提供了2种排泥方式,其一是短的沉淀时间,将大粒径和高密度的颗粒污泥存留在反应器中;其二是一种专有的污泥排除工艺,选择出反应器内潜在的可能存在进一步粒径增长和密度扩大从而破坏反应器运行稳定的大粒径和高密度的颗粒,并将其排除.以上2种方式保证了反应器内颗粒污泥的粒径长期维持在300～1 000μm,进而维持整个系统的稳定性.对新型反应器生成的颗粒污泥进行动力学参数的测定,该工艺所形成颗粒的能量维持系数为0.08～0.10,就新陈代谢活动的代谢途径而言,相比传统颗粒污泥系统发生较大改变,维持新陈代谢活动所消耗COD较传统工艺偏高.另外,出水水质COD的降解率平均达到92%,氨氮降解率平均达到60%.