Dissolved Oxygen Model Predictive Control for Activated Sludge Process Model Based on the Fuzzy C-means Cluster Algorithm

Minghe Li,Saifei Hu,Jianwei Xia,Jing Wang,Xiao-Na Song,Hao Shen 제어·로봇·시스템학회 2020 International Journal of Control, Automation, and Vol.18 No.9

In this work, the problem of predictive control of dissolved oxygen for the activated sludge process model with high nonlinearity and strong coupling is addressed. Firstly, the determination of the structure of fuzzy rules is displayed established upon Activated sludge model 1 (ASM1). Besides, the fuzzy space is divided through the clustering algorithm of fuzzy C-means. The corresponding parameters are estimated by means of the wellknown least squares method. Subsequently, a fuzzy predictive model of dissolved oxygen is established by using the historical data. The aim is to design a predictive controller that is capable of performing the online track of dissolved oxygen attributed to better dynamic response and steadier output in different weather. Ultimately, the availability and validity of the developed technique are verified by a comparison example.

Study on grinding mechanism and machining technology of Si3N4 ceramic spindle

Songhua Li,Chuang Li,Minghe Liu,Yonghua Wang,Chuang Zuo,Hao Zhang,Yifeng Gao 한양대학교 청정에너지연구소 2023 Journal of Ceramic Processing Research Vol.24 No.6

In order to improve the machining accuracy of the cylindrical surface of silicon nitride ceramic spindle, the machining technologyof the cylindrical surface of ceramic spindle was studied by high-speed universal cylindrical grinder in this experiment. Firstly, the primary and secondary order of the influence of various factors on the surface roughness of ceramic spindleis determined by orthogonal experiment, then the influence law of single grinding parameter on the surface roughness ofceramic spindle is explored by single factor experiment, and the prediction model of the grinding surface roughness value ofceramic spindle is calculated by numerical analysis software, and finally the optimal processing parameters of the cylindricalsurface of ceramic spindle are obtained. The experimental results show that the grinding surface roughness of silicon nitrideceramic spindle first decreases and then increases with the increase of grinding wheel linear speed and workpiece linearspeed, and then increases with the increase of transverse feed speed and axial feed speed. The relative error between the predictedvalue of the prediction model and the actual measured value is less than 5%, which shows that the prediction modelhas a good prediction effect and provides a theoretical basis for actual machining

Effect of ZnO on the microstructures and piezoelectric properties of K0.5Na0.5NbO3 ceramics

Zhuo Li,Xiangbang Cheng,Zhonghua Yao,Yang Liu,Hanxin Liu,Minghe Cao 한양대학교 세라믹연구소 2009 Journal of Ceramic Processing Research Vol.10 No.5

Lead-free ZnO added K0.5Na0.5NbO3 piezoelectric ceramics have been prepared by a conventional solid state process. The XRD results show that all the K0.5Na0.5NbO3 ceramics with various ZnO contents are single phase with an orthorhombic perovskite structure. The bulk density obtained by the Archimedes method indicates that the addition of ZnO improves the density of K0.5Na0.5NbO3 ceramics under the same sintering conditions. Especially, at a level of 1 mol% ZnO, the sample sintered at 1100 oC for 1h exhibits the highest bulk density (ρ = 4.28 g/㎤) and shows optimal piezoelectric properties, d33 = 135 pC/N and kp = 0.40. Lead-free ZnO added K0.5Na0.5NbO3 piezoelectric ceramics have been prepared by a conventional solid state process. The XRD results show that all the K0.5Na0.5NbO3 ceramics with various ZnO contents are single phase with an orthorhombic perovskite structure. The bulk density obtained by the Archimedes method indicates that the addition of ZnO improves the density of K0.5Na0.5NbO3 ceramics under the same sintering conditions. Especially, at a level of 1 mol% ZnO, the sample sintered at 1100 oC for 1h exhibits the highest bulk density (ρ = 4.28 g/㎤) and shows optimal piezoelectric properties, d33 = 135 pC/N and kp = 0.40.

Phylogenetic Analysis on the Bacteria Producing Non-Volatile Fungistatic Substances

ZhiFang Li,ChangSong Zou,YueQiu He,MingHe Mo,KeQin Zhang 한국미생물학회 2008 The journal of microbiology Vol.46 No.3

This study characterized the soil bacteria producing non-volatile fungistatic substances. Among the 2,100 colonies of soil bacteria randomly isolated from seven agricultural soil samples, 518 isolates (24.67% of total) showed fungistatic activity toward nematophagous fungi Paecilomyces lilacinus and Trichoderma viride by producing non-volatile substances. A phylogenetic analysis based on amplified ribosomal DNA restriction analysis (ARDRA) and 16S rDNA sequence placed the 518 bacteria in three groups of the domain Bacteria: Actinomycetales, Bacillales, and Gammaproteobacteria. Three genera, Arthrobacter, Bacillus, and Pseudomonas, were the most frequently encountered groups.

Effect of SiO2 additives on the microstructure and energy storage density of SrTiO3 ceramics

Guanghui Zhao,Yiqiu Li,Hanxing Liu,Jing Xu,Hua Hao,Minghe Cao,Zhiyong Yu 한양대학교 세라믹연구소 2012 Journal of Ceramic Processing Research Vol.13 No.3

The compositions of (1-x) SrTiO3-x SiO2 were prepared by a solid-state reaction. The crystalline structure, microstructure and energy storage performance were studied for the purpose of a potential application in high energy density capacitors. Fine grains with an average size of about 400 nm were obtained by adding SiO2 to SrTiO3 ceramics, which leads to a great enhancement in the breakdown performance of the samples. For SiO2-added samples, the notable increase in breakdown strength makes an obvious increase in energy storage density. With 15 vol.% addition, the sample exhibited an average breakdown strength of 36.1 kV/mm, and an energy storage density of 1.155 J/cm3.

Synthesis and characterization of Ba(TI1-xZRx)O₃ nanopowders by an aqueous coprecipitation method

Xiangbang Cheng,Zhuo Li,Zhonghua Yao,Yang Liu,Zhiyong Yu,Minghe Cao,Hanxing Liu 한양대학교 세라믹연구소 2008 Journal of Ceramic Processing Research Vol.9 No.6

In this study, single phase Ba(Ti1-xZrx)O3 (0 ≤ × ≤ 0.15) nanopowders have been synthesized successfully by an aqueous coprecipitation method at 85 oC without any further heat treatment. The lattice strain calculated by the Hall-Williamson method indicates that the broadening of the XRD peaks is primarily due to the size of particles not to the lattice strain. The increase of the lattice parameter indicates that Zr ions have entered the lattice and a solid solution was successfully obtained. Furthermore, the particle sizes calculated by the Sherrer formula from the XRD patterns are in agreement with the results of SEM and TEM images. The nanopowders obtained can be used to prepare Ba(Ti1-xZrx)O3 ceramics with a tailored grain size and homogeneous composition, and this is significant to investigate the size effect in Ba(Ti1-xZrx)O3 ceramics and understand the relaxor behavior thoroughly. In this study, single phase Ba(Ti1-xZrx)O3 (0 ≤ × ≤ 0.15) nanopowders have been synthesized successfully by an aqueous coprecipitation method at 85 oC without any further heat treatment. The lattice strain calculated by the Hall-Williamson method indicates that the broadening of the XRD peaks is primarily due to the size of particles not to the lattice strain. The increase of the lattice parameter indicates that Zr ions have entered the lattice and a solid solution was successfully obtained. Furthermore, the particle sizes calculated by the Sherrer formula from the XRD patterns are in agreement with the results of SEM and TEM images. The nanopowders obtained can be used to prepare Ba(Ti1-xZrx)O3 ceramics with a tailored grain size and homogeneous composition, and this is significant to investigate the size effect in Ba(Ti1-xZrx)O3 ceramics and understand the relaxor behavior thoroughly.

Preparation and property of submicrometre-crystalline Ba0.67Sr0.33TiO3 powders and ceramics

Hanxing Liu,Jing Xu,Bo He,Yiqiu Li,Minghe Cao,Hua Hao,Zhiyong Yu 한양대학교 세라믹연구소 2010 Journal of Ceramic Processing Research Vol.11 No.3

Submicrometre-particulate pure Ba0.67Sr0.33TiO3 (BST) powders approximately 110 nm in size have been prepared by a solidstate reaction technique. BST ceramics derived from powder calcined at different temperatures were fabricated with various sintering conditions. High-density BST ceramics at all sintering temperatures were obtained at a calcination temperature of 950 oC with the highest 99.6% of the theoretical density. Calcining at 950 oC and sintering at 1300 oC for 2 h , BST ceramic samples with an average grain size about 250 nm were obtained, showing satisfying dielectric properties and ferroelectric properties, with high permittivity εr = 7676, low loss factor tanδ = 0.01 and remanent polarization Pr = 9.2 μC/cm2, coercive electric field Ec = 1.58 kV/cm at room temperature.