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关键词： 聚醚有机硅   表面活性剂   异丙醇   油污清洗   表面张力  

摘要： 通过含氢聚甲基硅氧烷(PHMS)和三种聚醚(P4、P6和P8)发生硅氢加成反应,以异丙醇为溶剂,加入适量的铂作为催化剂,在水浴加热回流下制得聚醚有机硅表面活性剂。测定了活性剂的结构以及表面张力,确定了不同因素对油污清洗效率的影响,进而确定出较优的工艺参数。研究结果表明:PHMS-P6的清洗能力较强,其表面张力随浓度的增加逐渐下降;当浓度为0.05%时,表面张力降至最低值,此时聚醚有机硅表面活性剂的表面张力为37.6 mN/m。

关键词： 测压管   遥测   数据传输   精度比测   闸站工程  

摘要： 运用测压管监测闸站工程压力是水管单位主要技术管理任务之一,国内以及省内水库、闸站管理单位已有应用遥测技术监测测压管水位,但大多精度不够或故障率较高。以秦淮新河水利枢纽测压管遥测系统建设为实例,在选型时研究分析测压管管径、管质、温度场等要素,考虑水位计的功能、适应范围等因素,利用物联网技术,研发一体化智能遥测系统在闸站工程测压管监测系统,并通过实际比测,验证系统的可靠性,相关研究分析对同类型测压管监测系统建设具有参考作用。

关键词： 石英   角闪石   枝杈型表面活性剂   接触角   表面张力   石英微天平  

摘要： 针对铁矿石反浮选中含硅化合物浮选分离困难问题,研究组合阴离子捕收剂对石英的吸附机理,为低温浮选提供优质捕收剂。采用接触角测量仪、表面张力仪,红外光谱仪和石英微天平(QCM-D)对乙烯枝杈型表面活性剂+油酸钠组合捕收剂在浮选过程中的作用机理进行研究。结果表明:①组合捕收剂中多杈枝表面活性剂与脂肪酸的协同效应增强石英和角闪石疏水特性,使其接触角增大,含硅化合物中角闪石比石英更难吸附分选;②随捕收剂浓度的增加和温度的升高,组合捕收剂的表面张力逐渐减小,捕收能力增强且易生成稳定的泡沫层;③FTIR检测浸涂组合捕收剂后羧酸根的特征峰降低到1561 cm^-1和1416 cm^-1,发生明显的红移,表明C—O键能减弱,C—O键与活化后的石英表面发生化学吸附;④QCM-D检测结果显示,组合捕收剂在石英晶体表面吸附后,能量因子改变量达到6.23×10^-6。对齐大山选厂混磁精给矿在21℃的条件下进行"1粗1精3扫"闭路浮选流程试验,得到精矿全铁品位68.16%,铁回收率89.93%的良好指标。

关键词： 刷式密封   叉排管束   数值模拟   绕流阻力特性   计算流体力学   性能分析  

摘要： 以叉排管束模型刷丝束的二维截面建立数值计算模型,采用计算流体力学分别在瞬态和稳态下对流场进行数值模拟。分析了刷式密封中压差、轴向排数以及管距对绕流阻力特性的影响。研究结果表明:当压差在0.1~0.5MPa变化,前14排刷丝阻力逐渐增大,最大值为12N,第15排刷丝增大至30N。在0.5MPa的压差情况下,其管距增大0.5mm,总阻力增大100N。随着轴向排数的增加,刷丝绕流阻力减小且减小幅度逐渐降低。瞬态下,前14排刷丝绕流阻力增长幅度在0~0.005之间,第15排刷丝跳变至0.025~0.07之间,这样容易对刷丝根部焊接处造成疲劳破坏。

关键词： Drag-type turbine rotor   Startup   Angular velocity   Torque coefficient   Flow pattern  

摘要： The present study aims to reveal startup characteristics of a drag-type rotor as it is used to harness kinetic energy of flowing water. The rotational speed of the rotor and the hydraulic loads exerted on the rotor were correlated. After being validated through experimental results, a numerical scheme was used to investigate instantaneous flow parameter distributions and the torque on the rotor during the startup process. Startup processes were analyzed at different initial azimuthal angles. The results show that a successful startup of the rotor is featured by two consecutive stages, an acceleration stage and a transition stage, which is then followed by periodic fluctuations of the angular velocity. The startup failure is proved at two initial azimuthal angles of 70 degrees and 150 degrees. The former one is associated with positive static torque coefficient. The two failed startup processes share similar rotation positions where the rotor eventually halts. During the startup process, instantaneous flow patterns differ significantly from those obtained in static state. Small torque coefficients lead to an overall attenuation of the rotational speed and are ascribed to uniform pressure distributions over each side of the blade surface.

关键词： 表面张力   最大气泡压力法   教学改革   试剂选择  

摘要： 回顾了国内最大气泡压力法测定溶液表面张力等温线教学实验历年的设计与改进。比较了乙酸、丙酸、正丁酸、2-甲基丁酸、3-甲基丁酸、正戊酸、正己酸、甲醇、丙醇、异丙醇、正丁醇、异丁醇、乙二醇、1, 2-丙二醇、吐温20、吐温80、十二烷基硫酸钠等17种常用试剂在25℃下的表面张力等温线,及部分试剂在15,20,25,35℃下的表面张力等温线,指出正丁醇、异丙醇、丙醇是较为理想的教学实验备选试剂。

关键词： 费托合成油   磺化   α-烯烃磺酸钠   性能   表面张力  

摘要： 以费托合成油中的α-烯烃为原料,经过SO3磺化、中和、水解制备了煤基α-烯烃磺酸钠C1416AOS。测定了煤基C1416AOS的平衡表面张力、动态表面张力、润湿、泡沫和乳化性能,并与石油基C1416AOS进行了比较。结果表明:煤基C1416AOS和石油基C1416AOS的临界胶束浓度(cmc)无显著差异,煤基C1416AOS cmc时的表面张力低于石油基C1416AOS;煤基C1416AOS的动态表面张力低于石油基C1416AOS的动态表面张力;煤基C1416AOS和石油基C1416AOS的润湿时间相同;煤基C1416AOS泡沫体积略低于石油基C1416AOS;煤基C1416AOS与液体石蜡形成的乳液稳定性低于石油基C1416AOS。

关键词： Olive stones pyrolysis   Characteristic heating time   Characteristic pyrolysis time   Distributed activation energy model (DAEM)   Lumped capacitance method (LCM)  

摘要： Pyrolysis of crushed olive stone particles in a lab scale Bubbling Fluidized Bed (BFB) reactor was investigated. The time evolution of the pyrolysis conversion degree of the olive stone particles, while moving freely in the BFB, was determined from the evolution of the mass of olive stones remaining in the bed, measured by a precision scale holding the whole reactor installation. The experimental measurements of the pyrolysis conversion degree were employed to validate a simple model combining heat transfer and chemical kinetics, which is valid for thermally small particles. The model combines the Lumped Capacitance Method (LCM) and the simplified Distributed Activation Energy Model (DAEM) to account for heat transfer and pyrolysis chemical kinetics, respectively. The estimations of the combined LCM-DAEM model for the pyrolysis conversion degree were found to be in good agreement with the experimental measurements for the pyrolysis of olive kernels in a BFB operated at various bed temperatures, fluidizing gas velocities, and biomass particle size ranges. From the combined LCM-DAEM model, the characteristic heating time and the pyrolysis time of the olive stone particles were derived, obtaining a direct relation between these two parameters for constant values of the bed temperature. (C) 2020 Elsevier Ltd. All rights reserved.

关键词： Intracranial aneurysms   Flow classification parameter   Hemodynamics   Rupture status prediction   Classification parameter  

摘要： BACKGROUND: A simple dimensionless aneurysm number (An), which depends on geometry and flow pulsatility, was previously shown to distinguish the flow mode in intracranial aneurysms (IA): vortex mode with a dynamic vortex formation/evolution if An > 1, and cavity mode with a steady shear layer if An < 1. OBJECTIVE: To hypothesize that An > 1 can distinguish rupture status because vortex mode is associated with high oscillatory shear index, which, in turn, is statistically associated with rupture. METHODS: The above hypothesis is tested on a retrospective, consecutively collected database of 204 patient-specific IAs. The first 119 cases are assigned to training and the remainder to testing dataset An is calculated based on the pulsatility index (PI) approximated either from the literature or solving an optimization problem (denoted as (P) over capI). Student's t-test and logistic regression (LR) are used for hypothesis testing and data fitting, respectively. RESULTS: An can significantly discriminate ruptured and unruptured status with 95% confidence level (P < .0001). An (using PI) and <(A)over cap>n (using (P) over capI) significantly predict the ruptured IAs (for training dataset An: AUC = 0.85, (A) over capn: AUC = 0.90, and for testing dataset An: sensitivity = 94%, specificity = 33%, (A) over capn: sensitivity = 93.1%, specificity = 52.85%). CONCLUSION: An >1 predicts ruptured status. Unlike traditional hemodynamic parameters such as wall shear stress and oscillatory shear index, An has a physical threshold of one (does not depend on statistical analysis) and does not require time-consuming flow simulations. Therefore, An is a simple, practical discriminator of IA rupture status.

关键词： Sewage sludge   Fluidized bed   Pyrolysis   Condensate   Non-condensable gas  

摘要： This paper studied influences of temperature and additives on sewage sludge (SS) pyrolysis in a fluidized bed. The maximum condensate yield (17.07 wt%) was observed with Ca-bentonite at 650 degrees C. The yields of non-condensable gases rose significantly with addition of catalysts (e.g. kaolin). Fourier transform infrared (FTIR) spectra indicated catalysts led to the appearance of some compounds (e.g. alkanes, ketones, amines) in the pyrolysis oil (PO). Gas chromatography mass spectrometry (GC-MS) revealed that PO mainly contained organo-oxygen species, nitrogen-containing heterocyclic compounds, hydrocarbons and antibiotics. With catalysts addition, the main components in the organo-oxygen species were phenols (1.59%-13.78%) and ketones (1.15%-5.12%). The highest CO2 and CO yields were obtained with kaolin addition, while the lowest CO2 yield was reached by CaO. Nitrogen (N) and chlorine (Cl) mainly existed in char and liquid phase, whereas sulfur (S) was dominated in char, indicating that the existence form of S was stable. CaO had certain N retention ability and S retention capability was up to 99.64%. Cabentonite and CaO reduced the release of Cl and all catalysts contributed to reduction of HCN emission. (C) 2020 Elsevier Ltd. All rights reserved.