Effect of polycarboxylate-type superplasticizer on the paste fluidity based on the water film thickness of flocs

The excess water film theory and the properties of flocs are integrated to examine the effect of the polycarboxylate-type superplasticizer on the paste fluidity.The theory states that excess water can surround the flocs rather than the particles and that the cell consists of a floc and a superficial water film.Experiments on limestone powder pastes were conducted to verify the theory.The superplasticizer dosage(sp%)and the water–powder ratio by volume(Vw/Vp)were systematically varied.A sedimentation balance method was used to measure the size distribution of the flocs in the limestone powder pastes.The water film thickness(WFT)of flocs was then calculated and shown to determine the paste fluidity.Based on this WFT of flocs,the effect of the sp on the paste fluidity was determined and then compared with the effect of water.     

Consecutively spin-assembled layered nanoarchitectures of poly(sodium 4-styrene sulfonate) and poly(allylamine hydrochloride)

The recently established spin-coating electrostatic self-assembly (SCESA) technique has been shown to facilitate not only the rapid fabrication of polyelectrolyte multilayer assemblies, but also allow each layer to be easily controlled on a monomolecular scale by minimizing the film thickness across a substrate surface. In this paper, the influence of polyelectrolyte concentration on the amount and thickness of spin-deposited polymer films has been examined for a multilayer system of poly(allyamine hydrochloride) (PAH) and poly(sodium 4-styrenesulfonate) (PSS), when the washing steps employed for removing weakly bound polyelectrolytes on a resultant film on a substrate are excluded from the standard fabrication procedure of the SCESA method. The thickness of the spin-deposited PAH/PSS bilayer increased linearly for the PSS concentrations in the range from 1 to 10 mM with PAH constant at 1 mM, which demonstrates the uniform deposition of each layer material onto the thin film. The thickness of PAH/PSS bilayers increased from 1.43 ± 0.06 to 3.37 ± 0.08 nm as the PSS concentration increased from 1 to 10 mM, while the PAH concentration was kept constant at 1 mM. The multilayer films were found to be stable in a good solvent (H₂O) for at least 30 h, without any noticeable loss of the adsorbed layer component of the polyelectrolyte. This improvement to the SCESA method (exclusion of washing steps) provides a convenient way to create multilayer heterostructures with the thickness of each layer being easily adjusted.     

电力有源滤波器(APF)技术的探讨

随着大功率开关器件的广泛应用,电力系统谐波抑制及无功补偿问题变得日益迫切,电力有源滤波技术是解决上述问题的有效手段。首先简要介绍电力有源滤波技术的特点、基本原理,然后介绍APF的主要控制策略,最后对APF技术应用中应考虑的一些问题作简单介绍。     

单质铝水解机理研究(Ⅲ)——单质铝水解结晶过程研究

为了了解单质铝在水解过程中产物物相的变化规律,对单质铝水解过程进行了全过程监测,在反应的不同时段取样并对其进行XRD、SEM分析。以XRD分析结果为依据,对单质铝水解结晶过程中产物物相的变化进行了深入研究,彻底弄清了水解产物的生成顺序。以SEM分析为依据,对影响水解产物形貌、粒度及粒度分布的因素进行了研究。分析认为,团聚、二次成核、搅拌等因素对结晶过程中水解产物的形貌、粒度有显著影响。     

两种标准信号之间的函数变换

用函数变换的方法解决两种标准信号之间的转换，进而阐述了数学在解决实际问题中的应用。     

On the Role of the Law of Large Numbers in the Theory of Randomness

Problems of Information Transmission - In the first part of this article, we answer Kolmogorov's question (stated in 1963 in [1]) about exact conditions for the existence of random generators....     

基于FF现场总线PlantWeb工厂管控网的建立与应用

随着现场总线控制系统(FCS)在过程工业中的广泛应用，工厂管理层要求能够对生产层的直接管理，实现真正管控一体化的工厂模式。PlantWeb工厂管控网是管控一体化的一项新技术，因而本文针对扬子石化丁二烯生产装置，介绍了基于FF现场总线技术的PlantWeb工厂管控网的建立及其应用。     

应用于回归神经网络的基于梯度的典型算法的归纳与分析

首先给出了分层全回归神经网络的一个综合形式及其状态方程,然后归纳了几种典型的基于梯度的回归神经网络训练算法,描述了算法的具体步骤,并分析比较了算法特点及相互联系,最后指出对回归神经网络尤其是其训练算法研究存在的难点及研究重点。     

基于电压波形分析的十二相整流装置故障诊断

通过对十二相整流装置正常工作和故障运行时，整流元件电压波形的分析，提出了用以判断整流元件工作状态的特征函数，根据由该函数求出的特征值，可以对十二相整流装置的故障（包括复合故障）进行在线诊断，确定故障性质，并能准确定位到具体元件。     

材料脆化对汽轮机组启动预热和超速试验温度的影响

分析了长期服役汽轮机转子产生的材料脆化现象，提出了老机组的启动预热温度和超速试验温度应以转子的脆性转变温度变化量△FATT为依据进行制定，才能预防转子的脆性破坏，确保老机组的安全可靠运行。