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111.
本文用库仑滴定法结合Gran图,测定酸雨中的“自由氢离子”和“被束缚的氢离子”的总浓度。并对雨水中常出现的Fe~(3+)、Al~(3+)等离子的干扰影响也进行了探讨。并对10~(-4)~10~(-5)mol·L~(-1)浓度范围内标准硫酸溶液滴定结果进行了考察;以Gran函数((?)及(?)′)对滴定时间(t)作图,得一直线。相对误差在±5%左右。同时用该方法对武汉酸雨样品进行了实际测量。用标准加入法测得其回收率在90.8以上。 相似文献
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The flow of particulate two‐phase flow mixtures occur in several components of solid fuel combustion systems, such as the pressurised fluidised bed combustors (PFBC) and suspension‐fired coal boilers. A detailed understanding of the mixture characteristics in the conveying component can aid in refining and optimising its design. In this study, the flow of an isothermal, dilute two‐phase particulate mixture has been examined in a high curvature duct, which can be representative of that transporting the gas–solid mixture from the hot clean‐up section to the gas turbine combustor in a PFBC plant. The numerical study has been approached by utilising the Eulerian–Lagrangian methodology for describing the characteristics of the fluid and particulate phases. By assuming that the mixture is dilute and the particles are spherical, the governing particle momentum equations have been solved with appropriately prescribed boundary conditions. Turbulence effects on the particle dispersion were represented by a statistical model that accounts for both the turbulent eddy lifetime and the particle transit time scales. For the turbulent flow condition examined it was observed that mixtures with small particle diameters had low interphase slip velocities and low impaction probability with the pipe walls. Increasing the particle diameters (>50 μm) resulted in higher interphase slip velocities and, as expected, their impaction probability with the pipe walls was significantly increased. The particle dispersion is significant for the smaller sizes, whereas the larger particles are relatively insensitive to the gas turbulence. The main particle impaction region, and locations most prone to erosion damage, is estimated to be within an outer duct length of two to six times the duct diameter, when the duct radius of curvature to the duct diameter ratio is equal to unity. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
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单幅图像雨雾去除是计算机视觉研究的热点之一,现有的去雨方法往往需根据雨的特性恢复图像,忽视了场景中的雾以及场景深处雨累积的影响。提出了一种新型单幅图像去雨雾方法,设计了一种基于先验知识的三阶段单幅图像去雨雾框架。首先,将深度图作为图像透射率的引导,利用暗通道先验知识对输入图像的低频部分去雾,然后,采用残差网络学习高频雨痕特征,最后,引入条件生成对抗网络(conditional generative adversarial network,cGAN),对图像局部细节进行精细化修复,cGAN对图像的空间信息和纹理细节更为敏感,能有效恢复去雨雾过程中丢失或未能填补的细节。分别用高质量的合成雨雾数据集和真实数据集进行实验测试,结果表明,本文方法在峰值信噪比和结构相似度上均较基准方法优,能将雾浓度各异和雨分布变化情况下的图像恢复至细节丰富的干净场景图。 相似文献
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Two kinds of Ti-alloys, i.e., TiMo and TiNb alloys are manufactured in this paper, and their ultrasonic cavitation erosion behaviors in 0.1 M H2SO4 solution are evaluated by the mean depth erosion (MDE), SEM and white light photograph. The results show that MDE of TiMo and TiNb alloys obviously increase with increasing the cavitation erosion time, however, they evidently decrease with the increment of Mo or Nb content at each fixed cavitation erosion time, and even some large blank areas (uneroded areas) still exist on the sample surface after ultrasonic cavitation erosion for 2 h in the case of Ti10Mo and Ti20Nb samples, implying the enhanced anti-cavitation erosion property of Ti-alloy by adding Mo or Nb element. The MDE of Ti10Mo or Ti20Nb sample is lower than that of TC4 sample in the case of each cavitation erosion time, indicating the better cavitation erosion resistance of of Ti10Mo or Ti20Nb sample. The influences of Mo and Nb on the passivity of TiMo and TiNb alloys during the ultrasonic cavitation erosion are detected by potentiodynamic curves. The results display that Ti, TC4, TixMo (x = 1, 5, 10) and TixNb (x = 5, 10, 20) samples are all almost in the passive state within the potential region from 0VSCE to 1.5VSCE during ultrasonic cavitation erosion, and the passive current density evidently decreases with increasing Mo or Nb content, indicating the enhanced passive characteristic by adding Mo or Nb alloys during the ultrasonic cavitation erosion. 相似文献
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在分析星地链路几何结构及传播模型的基础上,研究基于联合代数重建技术的星地链路反演二维垂直降雨场的方法.利用实测降雨资料构建3类降雨场,并搭建3条17 GHz垂直极化星地链路进行数值仿真.实验结果表明:单星地链路无法实现二维垂直降雨场的重构,反演场与真实场的相关系数分别为0.556,0.504和0.364;基于双星地链路的反演结果和真实场的相关系数均高于0.98,平均偏差分别为0.122, 0.159和0.537 mm/h,欧式距离均低于0.9 mm/h,熵的相对误差均小于1.6%,基本实现了二维垂直降雨场的反演;三星地链路的应用进一步提升了反演精度,相关系数接近于1,能够精准重构降雨场.实验结果验证了基于星地链路的垂直降雨场反演方法的可行性、准确性和有效性.星地链路的架设和维护简单,探测降雨范围广,易于在高原、山区、海岛等传统地面观测资料缺失的地区使用,可以作为已有降水测量手段的补充. 相似文献
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为了探讨酸雨腐蚀环境对预应力混凝土梁抗弯性能的影响,制作了8根预应力混凝土梁,从混凝土强度等级、预应力度和钢绞线腐蚀率等方面,进行8根预应力混凝土梁的三分点静载试验。试验结果及分析表明,混凝土强度对屈服后试验梁的抗弯性能影响较大,对弹性阶段的刚度影响较小;随着预应力度的增加,试验梁的开裂荷载逐渐增大,进入裂缝阶段后,刚度下降速度逐渐加快;钢绞线腐蚀率越大,试验梁的极限抗弯承载力越低;腐蚀率在一定范围内(>3.22%),随着腐蚀率的增大,预应力混凝土梁试件的开裂弯矩、屈服弯矩和极限弯矩明显降低。根据试验结果,提出了模拟酸雨环境下预应力混凝土梁试件抗弯承载力的计算方法,同时采用ANSYS软件对预应力混凝土梁进行非线性有限元分析,将试验梁的计算值和模拟值与试验值进行比较,均吻合较好。 相似文献
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(S)-Gizzerosine, a potent inducer of gizzard erosion in chicks, was synthesized using successive zinc-mediated and palladium-catalyzed coupling reactions as the key steps. 相似文献