常规混凝沉淀工艺对阴离子表面活性剂的去除研究

随着阴离子表面活性剂(LAS)在民用和工业上的广泛应用,由此带来的水污染问题也日益加剧,对供水安全造成了很大威胁。针对目前大部分水厂仍采用混凝沉淀常规水处理工艺,考察了常规混凝沉淀工艺对LAS的去除效果。以Al2(SO4)3,PAC,FeCl3,PFS为混凝剂,非离子PAM为助凝剂进行了试验,结果表明混凝沉淀对LAS有一定的去除效果,而且有机物和LAS的去除有一定相关关系。但浊度与LAS的去除相关性较差。试验条件下对于LAS去除最佳混凝方案是投加量为40 mg/L的FeCl3。相同水质条件下铁盐混凝剂在除浊、除有机物和除LAS方面优于铝盐混凝剂。pH和水温对LAS的去除有一定影响,较低的pH和较高的水温均有利于LAS的去除。     

基于混合式注意力机制的语音识别研究

为了解决语音识别中基于卷积位置信息的混合式注意力机制无法提取长期有效位置信息的问题,提出了一种捕捉长期有效位置信息的新型混合式注意力机制。首先,对当前时刻生成的注意力得分作卷积来提取多通道特征图,并通过全局平均池化来得到恒定维度的特征向量;接着,引入长短期记忆网络（long short-term memory,LSTM）单元作为外部记忆模块,并以生成的特征向量作为输入,生成下一时刻的位置信息向量;最后,结合经典的LAS（listen,attend and spell）模型来验证提出方案的有效性。实验结果表明,该方案能充分考虑过去多个时刻的注意力得分。相对于基于卷积位置信息的LAS模型,该方案在纯净和含噪语音数据集上取得的标签错误率分别减少了1.8%和2.21%。     

Sulfonation with SO3: Relative reactivity of commercial alkylbenzene components

Commercial linear alkylbenzene components, such as linear alkylbenzene homologs and isomers, branched alkylbenzene and dialkyltetralins, have been synthesized and isolated. Equimolar mixtures have been prepared, and their relative velocities during the sulfonation reaction have been established.     

碳化硅纤维增强锂铝硅玻璃陶瓷界面粗糙度研究

采用复合材料界面微脱粘仪，根据纤维回推技术对ＳｉＣ纤维增强锂铝硅（ＬＡＳ）玻璃陶瓷基复合材料的纤维／基体界面粗糙度进行测试。结果表明该复合材料的界面粗糙度约８～１５ｎｍ。用ＴＥＭ，ＥＥＬＳ等手段，对界面的组成的形貌进行观察。分析和讨论了基体成分以及复合材料的热暴露对界面粗糙度的影响。发现Ｎｂ２Ｏ５在基体中的加入有助于减小界面粗糙度，而Ｂ２Ｏ３则使界面粗糙度上升。空气中热暴露使界面粗糙度急剧上升。     

Detergency of binary mixtures of LAS/STPP and LAS/Zeolites: influence of (Ca++) on the washing liquor

The influence of sodium tripolyphosphate (STPP) or zeolites on the detergency performance of linear alkylbenzene sulfonate (LAS) has been evaluated at different water hardness levels. This study demonstrates that STPP or zeolite behaves either as a sequestrant or through an important synergism with LAS, showing a minimum and a maximum in detergency performance, depending on the water hardness level. There is an optimum LAS/builder ratio for each individual water hardness level. This optimum has to be determined experimentally as it will not always necessarily coincide with the highest surfactant and/or builder concentrations.     

Toxicity of anionic detergents determined by Saccharomyces cerevisiae microarray analysis

Sodium n-dodecyl benzene sulfonate (LAS) and sodium dodecyl sulfate (SDS) are popular anionic detergents (surfactants) that are used worldwide and the toxicities of these chemicals have been characterized. We applied these chemicals in a DNA microarray bioassay and determined that the microarray data reflects previous findings and also provides some new information about anionic detergent toxicity. The mRNA expression profiles suggest that LAS and SDS cause damage to membranes and alterations in carbon metabolism, and induce the oxidative stress response. We also found that LAS and SDS induce the pleiotropic drug-resistance network, and that LAS and SDS may be pumped out of yeast cells by this network. Hierarchical clustering of the expression profiles showed that LAS and SDS cause similar features of toxicity and that the toxicity is similar to that of capsaicin but different from that of cadmium and mercury.     

Mechanisms in high-viscosity immersion-granulation

An atypical high-shear granulation process is investigated in which a fine inert powder is bound with a highly viscous surfactant paste. The mechanism comprises adsorption of powder particles onto paste fragments, breakage of powder-coated paste granules, micro-mixing of the granules with incorporation of the powder, granule growth via coalescence, and finally granule consolidation. These stages are supported by micrographic and granule size distribution data. The agglomeration process features two main mechanisms, namely binder distribution followed by granule consolidation and coalescence, the transition between which is shown to be dependent upon the operating parameters.A number of time-dependent consistency regimes can be identified and quantitatively described using bulk tapping compaction tests. Of particular interest is the trend in Hausner ratio, which provides information on the inter-granular friction and cohesivity. Various pseudo-steady state tapping parameters are used to track the agglomeration process, the results of which are consistent with the Iveson et al. (2001a, Powder Technology 117, 83-97) steady state agglomeration regime maps. The effects of paste/powder composition, paste rheology and mixing speed upon the agglomeration rate can be explained physically in terms of adsorption, viscous and mechanical energy dissipation mechanisms. In summary, the work introduces a preliminary analysis of an immersion-granulation mechanism in which a number of key features are identified.     

Evaluation of the rheological properties of sulfonic acids and sodium sulfonates

Sulfonic acids of linear alkylbenzene (LAB) are converted into the corresponding sodium salts to produce the most widely used anionic surfactant worldwide, linear alkylbenzene sulfonate (LAS). Used in many industrial applications and consumer products, the physical and mechanical properties of the sulfonates are strongly dependent on the LAB manufacturing process. Until recently, commercial alkylation of benzene has employed aluminum chloride or hydrogen fluoride catalysts, but a new fixed-bed alkylation process (DETAL) has been developed with improved 2-phenyl isomer selectivity and low tetralin concentration. In order to better understand the rheology of LAS in aqueous media, a comprehensive comparative evaluation of sulfonic acids and sodium sulfonates of the three LAB process derivatives has been done using dynamic mechanical rheometry, steady shear viscometry, and X-ray diffraction for phase identification. LAB sulfonic acids are Newtonian fluids in the temperature range of 20–60°C. The neat AlCl₃, HF, and DETAL sulfonic acids are Newtonian fluids within the temperature range of 20–60°C. At 30 wt%, all three sulfonates are Newtonian at 20–60°C, and the 40 wt% AlCl₃ sodium sulfonate remains in the Newtonian regime within this temperature range. Lamellar liquid crystalline phases have been identified for the sulfonates in the concentration range of 40–60 wt% in water at 20–60°C, and a hexagonal lattice phase also has been identified for DETAL sodium alkylbenzene sulfonate at 40 wt%, 60°C. The presence of anisotropic phases results in non-Newtonian pseudoplastic behavior with time-dependent viscosity functions.     

UV／H2O2用于中水回用预处理工艺试验研究

本试验采用UV／H2O2光氧化法处理含有较高浓度阴离子表面活性剂（LAS）的洗浴废水,研究了H2O2投加量、pH值、光照时间、紫外灯光强对LAS降解率的影响,并得出了一些有益的结论。     

一种LAS数据快速调度方法

为了提高数据分类处理时对大数据量LAS数据的访问速度,算法充分利用点集凸包的概念,提出了一种新的建立索引和快速调度的方法.通过实验证明,该方法在完全保留LAS数据原始文件存储的基础上,调度速度得到显著提高,完全可以满足数据分类处理的需要.