课程文献中心 更多>>

关键词： 表面张力   接触角   返排率   液阻   助排剂  

摘要： 为解决压裂液在超低渗储层返排过程中产生严重“液阻”效应而引发的储层伤害,采用氟碳表面活性剂与碳氢表面活性剂进行复配试验,研究表面活性剂协同效应、润湿性、热力学铺展作用,评价复合助排剂的助排率,形成了一种表面张力极低、界面张力满足压裂液通用技术要求的超低表面助排剂。室内实验表明,C12与OBS碳氢表面活性剂以0.4∶0.6(摩尔比)比例复配时其水溶液表面张力小于19.00 mN/m,界面张力小于1.50 mN/m,接触角为86.30°,水溶液助排率高达91.51%,同时超低表面张力助排剂与压裂液及其他添加剂均有良好的配伍性。超低表面张力助排剂在长庆超低渗油田的两口水平井进行了应用,返排率为73.19%~78.15%,返排率较之常规的助排剂提高16.30%~18.78%,助排效果较佳。

关键词： 动态表面张力   除草活性   安全性  

摘要： [目的]通过对药液动态表面张力(DST)的测定,研究除草剂药液动态表面张力与制剂活性及安全性的关系。[方法]通过不同助剂体系制备3%双氟·唑草酮悬乳剂,测定稀释液的动态表面张力及室内除草活性、安全性。[结果]在7 g a.i./hm^2剂量稀释下,A配方的最终10000 ms的动态表面张力为48.02 m N/m,低于其他配方,药效显示A配方的除草活性ED90值最低,为3.6 g a.i./hm^2,安全性较佳。[结论]不同3%双氟·唑草酮悬乳剂配方在3种稀释浓度下,分析动态表面张力数值表明优选配方的除草活性最佳,对小麦抑制率较低,这与室内生物活性测定结果一致。通过动态表面张力的测定,可以指导未来制剂配方开发中除草剂安全性与药效的平衡。

关键词： 限带白噪声   雨流幅值   概率密度函数   振动疲劳   数据拟合  

摘要： 对17种不同带宽系数的限带白噪声随机过程进行了雨流循环计数统计,提出了一个限带白噪声随机过程的雨流幅值概率密度函数(Probability density function,PDF)模型。该模型是Rayleigh分布和Weibull分布的线性组合,其中待定系数均为随机过程谱参数的函数。采用该模型对这17种随机过程的雨流幅值概率密度函数进行了公式拟合,探究了模型中待定参数与随机过程谱参数之间的关系,确定了模型表达式。对照随机过程的雨流计数统计结果,将该模型与Dirlik模型的预测精度进行了比较,结果表明该模型的预测效果优于Dirlik模型。

关键词： 短信平台   塑料膜   有机硅   重力影响   表面张力   水滴   棚膜   雾滴  

摘要： 1.甘肃读者(手机号:133××××9558)问:如何解决棚膜起雾滴的问题?答:可加入有机硅。有机硅的作用是帮助农药延展渗透,塑料膜上的雾滴可以用它来消除。有机硅的主要作用是破坏水滴的表面张力,有机硅碰到水滴后,会迅速破坏因水的张力形成的水滴,让水滴迅速延展铺开,同时由于水的重力影响,它会顺着棚膜下滑到地面,而不是直接下滴。

关键词： 多官能团表面活性剂   电导率   表面张力   起泡性能   乳化性能  

摘要： 以氯乙酰氯、间苯二甲酰氯、长链伯胺(碳链长度为8、12、14和16)和N,N-二甲基乙醇胺为原料合成了一系列含多官能团Gemini阳离子表面活性剂目标产物(I8、I12、I14和I16)。采用红外光谱和核磁氢谱对产物进行了结构表征。通过电导率法测量目标产物在不同温度下的临界胶束浓度(CMC),并计算出胶束的热力学参数(ΔGm^0、ΔHm^0、ΔSm^0);在298.15K条件下,通过表面张力法测定目标产物的表面张力(γCMC),并探讨了目标产物的泡沫性能和乳化性能。结果表明:目标产物有较低的临界胶束浓度值(CMC),在298.15K条件下,最低CMC达到0.05mmol/L;I16的γCMC最低为36.14mN/m;泡沫性和乳化性测试结果表明,在298.15K条件下,I8的起泡能力最好,I12和I14的稳泡性最好,均达到100%;目标产物对苯和二甲苯具有很好的乳化性能,其中I12对二甲苯的乳化性能最好,乳化时间为900s,I16对苯的乳化性能最好,乳化时间为629s。

关键词： Mixed pulsed fluidized bed   CFD-DEM   Pulse frequency   Gas flow ratio   Particle mixing  

摘要： Pulsed fluidized beds can make gas-solid mix and contact more uniform, therefore obviously improving heat transfer efficiency. The mixed pulsed fluidized bed, whose total gas flow is composed of stable gas flow and pulsed gas flow, is proposed in this research. Firstly, the experimental device for drying particles in a mixed pulsed fluidized bed is established. Pressure signals with different frequencies and gas flow ratios are collected, and flow pattern diagrams are obtained through a high-speed camera. Secondly, the CFD-DEM parallel numerical simulation method is constructed to research the mixed pulsed fluidized bed performance. Particle mixing, motion and heat transfer characteristics under different pulse frequencies and flow ratios are studied. Results show that particles in the mixed pulsed fluidized bed exhibit regular periodic motion, thereby promoting the mixing effect of particles. Moreover the bubble nucleation point moves to the bottom of the bed with the increasing pulse frequency. When the total gas velocity is relatively low, particle mixing effect can be enhanced by increasing the proportion of pulsed gas. However, when the velocity is relatively high, particle mixing effect will be enhanced by decreasing the proportion. (C) 2020 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.

关键词： Gross-Pitaevskii equation   Angular momentum rotation   Fourier pseudo-spectral method   Conservation law   Error estimate  

摘要： In this paper, a linearly-implicit Fourier pseudo-spectral method which preserves discrete mass and energy is developed for the time-dependent 3D Gross-Pitaevskii equation with additional angular momentum rotation. By establishing several discrete semi-norm equivalences between the Fourier pseudo-spectral method and the finite difference method, we establish an optimal H-1-error estimate for the proposed scheme without any restrictions on the grid ratio. The convergent rate of the numerical solution is proved to be of order O(N-r + tau(2)), where N is the number of spatial nodes and tau is the time step. Numerical results are reported to verify the efficiency and accuracy of our new method. (C) 2020 Elsevier B.V. All rights reserved.

关键词： Shoe manufacturing waste   Ash   Heavy metals   PCDD and PCDF   Ash fusion temperature  

摘要： The ash formation behaviour and associated compositional characteristics of the combustion of shoe manufacturing waste (SMW) in a 2.5 MW(th)pilot-scale circulating fluidized bed combustor (CFBC) were investigated to better understand the combustion behaviour and to find effective management strategy for the disposal of the ash streams produced. The compositional characterisations for the ashes produced from the pilot demonstrations showed the presence of a variety of trace heavy metals both in the fly ash and bottom ash. A pronounced uneven partitioning behaviour was observed on the distribution of these heavy metals between the fly ash and bottom ash, and it was found that all the heavy metals except chromium were preferentially enriched in the fly ash, with the contents of lead and cadmium in the fly ash being over 11 and 6 times higher than in the bottom ash. Leaching tests demonstrated that the concentrations of most of the aforementioned metals present in the leachates from the fly ash and bottom ash could meet the permissible limits for landfill disposal but with lead as an exception with its concentration in the fly ash leachates being over 2 times higher than the limit. The total PCDD and PCDF contents both in the fly ash and bottom ash were also much below the legal limit. To further understand the ash behaviour, the slagging and fouling tendency during SMW combustion in the CFBC was examined by use of the characterisation of the ash mineralogy and the results indicated that the SMW ash likely had low tendencies for slagging and fouling. The best two valorization routes for the SMW bottom ash and fly ash were recommended, one being to use them to produce colloidal silica medium to obtain safe inert filler and the other being to use them as the raw materials in the cement industry. [GRAPHICS] .

关键词： Drying  

摘要： This study reveals the low temperature high velocity (LTHV) assisted fluidized bed drying can preserve to the bioactive components of bee pollen. LTHV assisted fluidized bed drying characteristics of bee pollen. For this purpose, 100 g of the raw bee pollen samples are used to the investigation of drying characteristics at 4, 10, 24, and 40 degrees C, 40-50 humidity (%) and 6 m/s air velocity. In this regard, moisture loss, dimensionless mass loss, equilibrium moisture content, drying rate, drying time, mass shrinkage, some product characteristics, and sensory quality characteristic were investigated. Finally, the best drying air temperature was selected as 10 degrees C because the bee pollen samples had the best drying performance and sensory quality scores. LTHV assisted fluidized bed drying can be used for bioactive bee pollen drying. Practical applications The LTHV assisted fluidized bed drying is a new drying application that preserve to the sensitive food and bioactive food component. This method is usable for sensitive drying applications as medical and bioactive product production applications for the highest quality and safety production.