Papers by Keyword: Mechanism

Abstract: Neem (Azadirachta indica) leaf powder was modified using a chelating agent, ethylenediaminetetaraacetic dianhydride (EDTAD) and the adsorption performance in removing methylene blue (MB) was investigated under batch mode. The EDTAD modified neem leaf powder (ENLP) was characterized by spectroscopic technique and elemental analysis. Fourier transform infrared (FTIR) spectra indicated that the ROH, RCOOR, RCOO^- and RNH₂ groups were involved in the removal of MB. The maximum adsorption capacity calculated from the Langmuir isotherm model was 178.57 mg/g at 318 K. Adsorption kinetic was found to be fitted well with the pseudo-first-order model. This study suggests that ENLP can be an attractive adsorbent for MB removal from diluted industrial wastewater.

Abstract: An organic modified poly-polyacrylamide-Al-Zn-Fe (PPAZF) coagulant was prepared by adding polyacrylamide (PAM) as additives in poly-Al-Zn-Fe (PAZF). The coagulation performance of PPAZF was investigated compared to that of PAZF and polyaluminium chloride (PAC) in treating domestic sewage and pharmaceutical wastewater. The results showed that PPAZF not only had better removal of turbidity and chemical oxygen demand (COD_Cr) than PZAF and PAC at the optimal dosages of 148 mg·L^-1, but also produced large and dense flocs. Compared to PAZF and PAC, the removal of COD_Cr by PPAZF was greatly improved at lower dosage. In addition, experimental results indicated the main mechanism of PPAZF is a comprehensive coagulation effect and chemical reaction.

Abstract: Based on the analysis of electronic identity management system to be constructed for challenge, this paper analyzes the development bottlenecks of network real-name system in China, then proposes a electronic identity management model for China's conditions, and discusses the issues about the operating mechanism, information security, personal privacy protection and legal basis that model may cause, finally provides corresponding legal suggestions.

Abstract: The mechanism that hydrated lime can improve water stability of asphalt mixture was analyzed through contrasting the performance of hydrated lime and ordinary limestone ore filler. The test results indicated that hydrated lime can obviously improve the water stability of asphalt mixture.

Abstract: Specimens of Al-and Ti-alloys and turbine blades of Ni-based alloy were considered in the case of crack origination at the surface, subsurface, and at the inner surface of turbine blades. Aircraft structures such as hydrocylinders of Al-based alloy and landing gear of high-strength-steel were also considered. There was used acoustic emission (AE) monitoring to fix moment of crack occurring and, then, analyzing its growth. Fracture surface features appearance was compared with AE-signals regularities based on fractographic analyses. To indicate the crack origination moment it was introduced α-criterion. This criterion characterized drastically increase in summarized AE-signals appearing in dependence on cyclic loads number. During crack propagation, there was used Elber-portion of opened crack to register AE-signals in cyclic loads. It was demonstrated crack increment in unloading portion of cyclic loads with fatigue striations formation. Two aircraft structures of hydrocylinders and shock strut of landing gear were tested on the special test facilities and AE-monitoring was conducted. Effectiveness of α-criterion using for crack registration in the high-cycle fatigue regime was demonstrated applicably to crack appearance on the internal surface and subsurface. The discovered dependences of summarized AE-signals on number of cycles were compared with fracture surface patterns and briefly discussed.

Abstract: Bromine atom with strong electronegativity was introduced to a position of dodecanoic acid as a new type collector DZF-3 in iron ore flotation. The structure of DZF-3 synthesized in the paper is verified by FT-IR and ¹H-NMR. And the collecting performances of DZF-3 are also presented through a series of flotation experiments of single minerals. Results show that DZF-3 is a kind of efficient collector especially used in room temperature in reverse flotation. Moreover, DZF-3 can collect quartz particles without activated by CaCl₂. Mechanism analysis shows that electronegativity and collecting performance of the collecting group-COO^- are increased by bromine atom. The enhancement of electronegative of dodecanoic acid by Br substituted in a position results in the competitive adsorption among active sites of Br atom and O atoms of carboxyl group with hydroxyl of quartz surface, then there occurs a chemical reaction between the Siⁿ⁺(n= 0-4) in quartz surface and active sites in DZF-3 molecules.

Abstract: For the middlings (containing siderite) separated from Dong Anshan carbonaceous iron ore which was dressed by a two-step flotation process, using roasting-magnetic and regrinding-magnetic separation, the iron concentrate with iron grade and iron recovery of 60.31%, 87.49% was obtained. Mechanism of reduction-roasting was studied by means of XRD in the end.

Abstract: The useful minerals of Jinchuan high-grade copper and nickel suphfide ores were mainly nickel and copper, whose grade were respectively 1.42% and 1.01%. The content of MgO and SiO₂, main gangue components, reached 57.89%. The key to improve the separation indexes of flotation concentrate was to inhibit the gangue minerals effectively, therefore, the effects of different kinds of regulators on Jinchuan high grade copper-nickel ores by flotation were studied. Considering the grade and recovery of concentrate comprehensively, the optimal regulator of mineral flotation was determined to be the combination of sodium hexametaphosphate and citric acid, and the dosage were 300g/t and 500g/t, respectively. After analyzing the mechanism of the two regulators, the combined reagents could reduce the isoelectric point of gangue minerals, decreasing the adsorption between gangue minerals and valuable minerals. In addition, the reagents were able to eliminate the activation of useless ions such as Ca²⁺ and Ni²⁺ on the gangue minerals and improve the ion composition of pulp, increasing the difference of floatability between gangue and useful minerals.

Abstract: To compare with the other gear manufacturing methods, the hot roll forming process is applied in forming large module gear. The hot gear rolling theory is realized by modeling in Solidworks and Deform-3D, the finite element model (FEM) that coupled deformation and heat transfer was established, and the FE model velocity boundaries were set by converting the workpiece rotation into the revolution speed of the roller. The total displacement of metal flow, folding angel of teeth, effect strain and the temperature distribution of the part were obtained in the whole process of hot gear rolling, also the rolling force was predicted by simulation. The simulation results reveal the forming mechanism, and the rolling experiments were carried out with self-designed rolling mill, which verify that the hot roll forming large gear is feasible.

Abstract: Epicyclic gear trains have been broadly applied in engineering practice. In this paper, kinematic chains (K.C.) with single-joint (S.J.) were applied to innovative synthesis of the epicyclic gear trains. The method of the innovative synthesis of the epicyclic gear trains was presented. Not only the epicyclic gear trains in common uses were obtained, but some new types of epicyclic gear trains that are got difficultly by means of conventional combination method were gained. Thereby, a new way has been offered for the innovative synthesis of the epicyclic gear trains, at the same time, a way has also been offered for practical application of some multi-link kinematic chains gained by using the theory of type-number synthesis of the K.C. with S.J.. Examples show that the method presented in this paper is right and feasible, and the method is efficient and practical for the innovative synthesis of the epicyclic gear trains.