ANN model for prediction of powder packing

A multilayer feed forward backpropagation (MFFB) learning algorithm was used as an artificial neural network (ANN) tool to predict packing of fused alumina powder mixtures of three different sizes in green state. The data used in model construction were collected by mixing and pressing powders with average particle sizes of 350, 30 and 3 μm and with narrow particle size distributions. The data sets that were composed of green densities of cylindrical pellets were first randomly partitioned into two for training and testing of the ANN models. Based on the training data an ANN model of the packing efficiencies was created with low average error levels (3.36%). Testing of the model was also performed with successfully good average error levels of 3.39%.     

半自动粉状PVC包装机控制系统的改造

以OMRON CPM2A系列PLC和CB920配料控制器为中心控制单元,设计了半自动粉状PVC包装机的控制系统,介绍了控制系统的硬件配置和工作过程,采用该控制系统的包装机操作方便,故障率低,包装速度快。     

Characterization of the granular packing and percolation threshold of reactive powder concrete

Reactive powder concrete (RPC) is a new cement-based material developed through microstructural engineering. RPC is composed of very fine powders: sand, crushed quartz and silica fume, all with particle sizes comprised between 300 and 0.02 μm, and a low water content, W/C<0.20. A very dense matrix is achieved by optimizing the granular packing of these powders. This compactness confers to RPC ultrahigh strength and durability.

The hydration kinetic of the cementitious matrix using electrical conductivity and isothermal calorimetry is presented. A linear relationship between the logarithm of conductivity ln(σ) and the degree of hydration , has been found:

ln(σ)=A_v−B_v

where A_v depends on the nature and the dosage of the different mineral and organic components, and B_v is an invariant related to the granular packing. From 19 different RPC compositions, an average value of 12.1 with a standard deviation of 1.7 were found for B_v. The capillary porosity percolation threshold was also deduced from this relationship. It has been found that when the degree of hydration is equal to 26%, the capillary pore space is discontinuous. This last result is in agreement with the prediction of the NIST microstructural model by Bentz and Garboczi [D., Bentz, E. Garboczi, Percolation of phases in a three-dimensional cement paste microstructural model, Cem Concr Res 21 (2) (1991) 325–344]. A continuous determination of the degree of hydration based on electrical conductivity is proposed.     

Inhomogeneity of powder packing in compacts and strength of the ceramics obtained

Results of studying the effect of the packing inhomogeneity of the powder compact on the strength of sintered corundum ceramics are presented. In the powders used for molding powder compacts, agglomerates of various sizes were formed artificially. Under the same sintering conditions no substantial difference in the density or grain size of materials that initially differed in the inhomogeneity of particle packing were observed. Strength measurements revealed an inverse dependence of the strength on the degree of powder inhomogeneity in the starting compact. Translated from Ogneupory i Tekhnicheskaya Keramika, No. 5, pp. 14–19, May, 1997.     

Vibrovacuum compaction of fine powders and its influence on isostatic molding

Conclusions An apparatus was developed for an investigation of the vibrovacuum compaction with a liquid auxiliary load of powders prior to isostatic molding, and the efficiency of the process was determined.The relations were determined between the compaction of the powders with vibrovacuum activation and their bulk density and angle of repose, and between the distortion of the shape of the green product and the compressibility in isostatic molding.An efficient flow sheet was developed for the vibrovacuum compaction of products from fine-ground zircon and chromic oxide prior to their isostatic molding, viz., pouring the powder into the vibrating mold, applying the vacuum, vibrocompaction, and vibrocompaction with an auxiliary load.Methods are recommended for producing the vacuum and vibration and for applying the liquid auxiliary load.Translated from Ogneupory, Vol. 18, No. 8, pp. 32–39, August, 1977.     

多元凝胶紧密堆积对活性粉末混凝土的影响

讨论了C(水泥)+UPFA(超细粉煤灰)、C+SF(硅灰)二元和C+UPFA+SF三元胶凝材料体系中,新拌浆体的黏度、流动度与浆体的相对密实度的关系,以及相对密实度和流动度对活性粉末混凝土RPC强度的影响.实验结果表明:(1)双掺硅灰和超细粉煤灰,随活性粉末掺量的增加,新拌浆体的黏度增加,流动性下降,相对密实度提高;(2)双掺硅灰和超细粉煤灰的RPC强度远高于单掺硅灰时的强度;(3)RPC强度与体系中胶凝材料的相对密实度和流动度有关,复掺硅灰和超细粉煤灰,当密实度为0.669,流动度为182mm时,其RPC的7d抗压强度高迭150.4MPa.     

填料塔的填料层高度和塔径计算实例

用闲置金属鞍环填料对填料塔进行防腐处理。介绍了利用现有引风机的条件下,填料塔塔径、塔高的计算示例。     

填料因子变化时散堆填料泛点气速数值算法

泛点气速是填料塔设计的重要参数,Eckert关联图为目前工程上运用较为广泛的泛点气速求取方法。文中基于散堆填料的Eckert关联图,在考虑泛点填料因子f随液体泛点喷淋密度Lf变化的条件下,提出了泛点气速uf的数值算法;推导出泛点气速uf的表达式为一个高度非线性化方程,并给出了该方程的2种求解方法。同时举例计算了一个散堆填料的泛点气速,并和著名的塔器流体力学计算软件(WPTR)计算结果做了对比。结果表明:文中的计算结果和WPTR的结果完全吻合;所使用的方程求解方法 Aitken-Steffensen具有快速、稳定的收敛性,可用于散堆填料的泛点气速计算。     

填料塔中规整填料及相关装置的设计

介绍了颗粒型填料和规整填料,分析了气液再分布装置的设计要求、喷淋密度确定、设计计算、结构设计等,指出溢流槽式再分布器是适应性较好的分布器,特别适用于大流量操作。     

Supported catalytic packing prepared from ceramic packing for reactive distillation of ethyl acetate

In this work, a strategy of “etching-modification filling-graft copolymerization” was proposed to load the acidic ionic polyionic liquid on the smooth ceramic surface. In this way, commercial ceramic Raschig rings were successfully transformed into the supported catalytic packing for the reactive distillation, and were further evaluated with esterification reaction of ethyl acetate by means of the fully mixed reactor, the ultrasonic destruction, the cyclic catalysis reaction and the lab-scale distillation column experiment. This catalyst coating has good adhesion with the substrate. It can withstand 24 h of ultrasound damage and shows good stability in three cycle catalytic experiments. This kind of coated catalyst has better catalytic activity than the commercial Amberlyst 15 dry. In the lab-scale reaction distillation, the supported catalyst Raschig ring can achieve a higher conversion in comparison with the tea bag catalytic packing of Amberlyst 15 dry under some conditions.     

碳化硅规整填料的性能实验研究

为了研究新型多孔碳化硅规整填料的分离性能,文中对碳化硅规整填料进行了流体力学实验和传质实验。为了进一步提高碳化硅规整填料的传质性能,实验用硅酸钠溶液对碳化硅规整填料进行了表面改性处理,提高了填料表面的润湿性。实验结果表明:碳化硅规整填料具有较低的压降,较小的持液量,其理论板数可达到5块板以上,说明碳化硅规整填料是一种新型高效规整填料。同时获得了该填料的填料压降、泛点气速、持液量等流体力学性能数据,及填料层压降和液泛气速的关联式。     

Becoming random close packing

The problem of random close packing has been analyzed as a task of self-development with the doubling of the scale at the stage of becoming. It has been shown that the site of a transforming body at this stage can be described by hexagons in the two-dimensional case and by tetrakaidecahedra in the three-dimensional case. When their vertices, equidistant from the center, are distributed so that the smallest distance between them is largest among its all possible values, the fraction of the surrounding Euclidean space, which is occupied by the figures, coincides with the capacity of a random close packing. The capacity takes the value 0.827, in the two-dimensional case, or one of the two values, i.e., 0.6366 and 0.6457, in the three-dimensional case. The result obtained provides insight into the geometric meaning of the isotropic random close packing and serves to accept the existence of its two forms in the three-dimensional case.     

化妆品包装设计的创新

论述了化妆品包装盒、包装容器盖子及封口的创新设计。介绍了化妆品包装纸盒的印刷、装饰和造型的新颖以及新材料的选择。介绍了包装容器盖子以及封口的一些创新设计。盖子和封口与化妆品包装的其他领域一样,能够随着潮流而发生变化,指出了当今化妆品包装容器盖子和封口的发展潮流。     

香粉、爽身粉和痱子粉的行业标准

本标准规定了粉剂产品中的香粉、爽身粉和痱子粉的产品分类、技术要求、试验方法、检验规则和标志、包装、运输、贮存等要求。     

保压时间和保压压力对注塑制品厚度分布的影响

通过实验研究了保压压力和保压时间对制品厚度分布的影响,所得的结论可以指导塑件和模具的设计。