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8 results on '"Xiong, C.-h."'

6. Stability analysis in milling of thin-walled workpieces with emphasis on the structural effect

Author

Zhang, X-J, Xiong, C-H, Ding, Y, and Zhang, X-M

Abstract

Regenerative chatter easily occurs in milling and has become the common limitation to achieve good surface quality and high productivity. For the purpose of chatter avoidance, the structural effect of the thin-walled part should be considered for the milling chatter stability analysis for the optimization of axial cutting depth and spindle speed pairs. The main objective of this paper is to examine the link between the structural modes (i.e. modal shapes) and the chatter stability limits in the case of finish milling thin-walled workpieces. In this paper, the dynamic stability of the milling process of thin-walled workpieces is investigated through a two-degree-of-freedom mechanical model. The mathematical relationship between the critical axial depth and the thin-walled part modal shapes is deduced and an optimal calculation process of milling stability lobes is presented. Peripheral milling of aluminium alloy (2A70 Al) plates is carried out on a computer numerically controlled (CNC) five-axis super high-speed machining centre to validate the method. The experimental results agree with the prediction by the presented method. Additionally, the experimental results show that the cutting stability is also influenced by the modal frequencies of the thin-walled part, which have a great influence on the milling stability analysis when the tool passing frequency (i.e. the inverse of the tooth passing period) harmonics are close to the modal frequencies of the part. The presented method is effective in the prediction of milling chatter limits in the thin-walled case for the optimization of machining parameters.

Published
2010
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7. [Characteristics on molecular epidemiology of Brucella melitensis in Jiangxi province].

Author

Zong J, Ding S, Tian GZ, Xia GH, Xiong CH, Wang P, Xu XQ, and Xu JM

Subjects
Brucella melitensis isolation & purification, Brucellosis epidemiology, China epidemiology, Genotype, Humans, Minisatellite Repeats genetics, Molecular Epidemiology, Brucella melitensis genetics, Brucellosis microbiology
Abstract

Objective: To understand the molecular characteristics and correlation among isolated strains of Brucella melitensis (BM) so as to improve the strategies on prevention and control of the disease in Jiangxi province. Methods: A total of 25 strains of BM isolated from human in 17 counties of Jiangxi province were analyzed by multiple locus variable-number tandem repeat analysis (MLVA) method. Results: A total of 25 strains of BM were classified into 24 independent genotypes with similarities between 67.00% and 100.00% and Simpson index between 0.000 and 0.773. There were 3 genotypes in MLVA8, including 60.00% (15/25) as 42 genotype, 32.00% (8/25) as 43 genotype, and 8.00% (2/25) as 63 genotype, respectively. There were 7 genotypes in MLVA11 identified, with 116 genotype and 125 genotype the main genotypes, accounting for 56.00% (14/25) of all the identified strains. Conclusions: Genes from all the 25 strains of BM that isolated from human being were with high genetic diversities, and various, genotypes. However, no obvious epidemiological correlation was noticed among these strains, indicating the complexity of the source of infection on Brucella in Jiangxi province.

Published
2020
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8. Study on the adsorption of cadmium(II) from aqueous solution by D152 resin.

Author

Xiong CH and Yao CP

Subjects
Adsorption, Feasibility Studies, Hydrogen-Ion Concentration, Solutions, Temperature, Thermodynamics, Cadmium isolation & purification, Resins, Synthetic chemistry, Water Pollutants, Chemical isolation & purification, Water Purification methods
Abstract

The feasibility of using D152 resin as an adsorbent for cadmium(II) was examined. The adsorption capacity of D152 resin for cadmium(II) ions was studied as a function of solution pH, temperature and contact time. The optimal pH for the adsorption of cadmium(II) ions was found to be 5.95 in the HAc-NaAc system. The maximum uptake capacity of cadmium(II) was estimated to 378 mg/g D152 resin at 298 K, at an initial pH value of 5.95. The results obtained from equilibrium adsorption studies were conformed to the Langmuir and Freundlich and the correlation coefficients have been evaluated. The apparent adsorption rate constant was k(298 K)=4.01 x 10(-5)s(-1), and the apparent activation energy was 2.78 kJ/mol. Thermodynamic parameters, DeltaS was 108 J/(mol K), heat of adsorption (Delta H) value of 12.8 kJ/mol indicated the endothermic nature of the adsorption process, and a decrease of Gibbs free energy (Delta G) with increasing temperature also indicated the spontaneous nature of the process, respectively. The elution tests were carried out using various mixed reagents. The maximum elution percent of cadmium(II) ions were obtained when the reagent 0.5 mol/L HCl was used.

Published
2009
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