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以贫甲醇泵的扬程计算为例,对HG/T 20570.5—1995《泵的系统特性计算和设备相对安装高度的确定》中的离心泵压差计算公式进行了探讨,明确了泵输送过程中液体密度发生变化的情况下如何计算离心泵的扬程,并对标准中的计算公式进行了修正,以便可以适用于更多的计算工况。 相似文献
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本文涉及到吸入液面为减压、输送料液温度接近汽化温度情况下泵的安装高度,提出使用泵的安装高度必须据使用须要核算确定。 相似文献
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为了弄清楚膜结构自动止液器的止液原理及安装使用要求,以促进产品推广应用,首先测试了止液膜的孔径结构及尺寸分布、接触角和耐静水压值,然后对其止液机理进行了理论分析,并建立了止液膜的止液高度、安装高度和孔径要求的计算公式,最后实验模拟验证了自动止液器输液器的止液效果.结果发现,止液膜通过与药液间产生表面张力,来平衡止液膜和针头间药液柱产生的静水压,从而实现止液效果.考虑一般输液管的长度在1.6 m左右,止液膜的平均孔径必须小于11.85 μm才具有止液效果.当要求止液器具有防血液回流效果时,其安装高度应该大于12.2 cm. 相似文献
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开展综合化学实验 提高学生创新能力 总被引:6,自引:1,他引:5
实验教学是高校培养学生创新能力的重要环节,文章探讨了师范院校开设综合化学实验的必要性,并就如何构建综合化学实验体系,以及如何对其内容和教学方式进行改革作了探讨。 相似文献
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Miriam M. Schwarz Thilo Richter Rion Pearson Asman Tamang Torsten Balster Dietmar Knipp Veit Wagner 《Journal of Applied Electrochemistry》2014,44(5):613-620
This paper outlined how to control density and shape of electrodeposited ZnO nanorods to achieve high scattering properties. Light scattering at nanostructured metal–semiconductor interfaces is a proven method to improve absorption in photovoltaic devices. Adjustment of nanostructure shape and mean distance is critical to achieve efficient light scattering. A simple model is introduced that predicts maximal suppression of the specular transmitted light, resulting in maximal light scattering. This model predicts in an ideal case, 50 % nanostructure coverage of the electrode. Furthermore, an optimal nanostructure height has been determined depending on the incident wavelength and the refractive indices. Experimentally, the crystal density on ITO substrates was adjusted by pulsing the deposition potential, thus, removing the requirement for an additional seeding layer. The solution of the diffusion equation indicated a break-to-pulse ratio of at least 2.4 for an efficient control of the crystal density during pulsed electrodeposition. In addition, the structure height was set by varying the number of pulse cycles. Such tailored ZnO nanostructures showed a suppression of the specular transmitted light beam of 83.5 % and a diffusive forward scattering efficiency of 39 % at a wavelength of 406 nm. Thus, the optical absorption of e.g. an 80-nm thick polymeric active layer of P3HT could be increased by 47 % by applying such tailored ZnO nanostructures. 相似文献
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主要讨论在计算机软件应用系统中安全性的处理及其实现。对于任何应用系统 ,安全性是衡量系统性能的一个重要标准 ,而对一些用户接口设置密码则是保证系统安全的重要手段。结合作者在实际应用中的体会 ,根据某些算法 ,对用户密码进行了加密处理以及对加密后的数据进行了保护 ,并介绍如何在VB中实现 相似文献
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Juchirl Park Yue Huang Richard Turton Parviz Famouri Edward J. Boyle 《Powder Technology》2005,150(3):176-184
Circulating fluidized beds (CFBs) are used widely in the chemical industry. Knowing or estimating the bed height in the standpipe and the solids circulation rate are essential for effective control of the system. This paper incorporates a 2-region model to calculate the bed height in the standpipe with a Kalman filter algorithm to estimate the solids circulation rate (SCR). Simulations of both the standpipe bed height and SCR were compared with experimental data and shown to give good agreement.
In addition, a neural network method was applied to model the entire cold flow CFB system and measured data sets were used to train the neurons of the network. Finally, a linear controller was applied to control both the bed height and solids circulation rate to desired set points. Simulations were performed for both positive and negative step inputs for both variables and satisfactory control was demonstrated using this controller in combination with the neutral network and Kalman estimator. 相似文献
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介绍攀钢1#方坯连铸后区辊道控制的基本原理,概述西门子S7-400PLC与M440变频器通过现场总线Profibus-DP怎样连接起来,阐述PLC硬件组态如何进行、变频器相应参数如何设置,并提出PLC和变频器之间进行数据交换的方法。 相似文献
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随着现代人“健康第一”意识的增强,体育消费作为高校学生的一种时尚追求,已有越来越多的学生加入了其中。本文针对大学生体育消费行为的意识、结构、动机和水平进行了调查与社会心理学分析,并对如何正确引导高校学生进行合理体育消费、培养终身体育意识提出了有关建议。 相似文献
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文章以宁波万华项目冷冻水系统为例,从工程设计角度主要介绍溴化锂机组的原理、选型,及其水系统的配置,分析如何设计一套经济合理的冷冻水系统。 相似文献