Applied Mechanics and Materials Vols. 341-342

Abstract: The low temperature (T) Raman spectroscopic study on the geometrically frustrated clinoatacamite γ-Cu₂(OH)₃Cl is reported. By measuring the T-dependent spectral profiles and representative modes, we have obtained auxiliary evidence of successive magnetic transitions near T_c1 =18.1 K and T_c2 =6.4 K determined accurately by the magnetic experiments in the Raman band frequencies and peak widths of the representative modes for magnetic research conclusions and observed a pronounced Raman spectroscopy background featuring a broad continuum at all Ts. A quantitative analysis reveals spin fluctuations on a picosecond time scale in the intermediate phase.

Abstract: The physical mathematic model for heat transfer and convection in laser molten pool established. 3D-computer simulation of temperature and fluid fields has been completed with finite difference method. It is shown that in laser molten pool there is a strong fluid flow, which is symmetrical in XY plane and anti symmetric in XZ plane. Due to effects of convection and heat transfer laser molten pool is widen. Surface tension gradient is the main drawing force for convection.

Abstract: The fractal surface profile can usually be represented by WM function, A fractal dimension and a fractal roughness parameter are very important characteristic parameters in WM function. Usually, fractal scaling parameter γ was set to equal to 1.5, fractal dimension can be determined by the structure function method, but the accurately identification of the fractal roughness parameter is still a problem. In the present study, a simply numerical scheme with clear routine was developed to determine the fractal roughness parameter, and the fractal roughness parameter were recovered with reasonable accuracy from the numerically generated rough surface profile based WM function.

Abstract: For flotation characteristics of complex sulfide mineral of low-tin in Guangxi Dachang mine, fluid dynamics software FLUENT was applied to simulate the turbulence intensity of slurry fluid in flotation machine at different inflation pressures. The effect of flow field characteristics was gotten for flotation machine. Simulation results show that the best inflation pressure was 120000 Pa.

Abstract: A vector hysteresis model referred to as the Preisach-Stoner-Wohlfarth (PSW) model has been recently presented. The crux of the model is the definition of a vector hysteron. In this paper, the effects of interaction field and applied field angle on the magnetization of the vector hysteron are studied in detail. The center of the hysteresis loops of hysteron is displaced because of the effect of interaction field. The energy loss for each hysteron is verified when the critical surface is crossed.

Abstract: Leakage causes of boiler low temperature reheater were discussed by means of macroscopic inspection, chemical composition analysis, metallurgical microstructure examination, SEM and EDS fracture analysis. Results showed that the reheater leakage occurred for cracks originating from the fillet seam of ear plate. The main causes lie in improper structural design of the ear plate welding directly on the reheater elbow where suffered from complicated stress condition, wall thinning and out-of-round. In addition, as a weak zone, heat effect zone of the fillet welding seam was more likely to crack under fatigue stress for frequent unit start and stop and pipeline vibration. Installation stress existed between the ear plate and support block also contributed to the cracking. Suggestions were provided to avoid similar accident based on the comprehensive analysis of leakage causes.

Abstract: In view of pore distribution in coal, this paper applies BJH method that is based on the cylinder theory and adopts cryogenic liquid nitrogen adsorption method to carry out experimental investigation on pore structure of No.3U coal seam in Sanhekou Coalmine, obtaining the fact that pore structure of No.3U coal is complicated, the cool pores are mostly flask pores, others are the parallel plate pores with one end closed and the cylinder pores with one end closed; According to the distribution of BJH pore volume and pore surface area, ultramicropores with apertures less than 10 nm are among the most; Then obtain the average BET specific surface area, the distribution of BJH pore volume and pore area, average single-point total pore volume and most probable pore .etc, which conducive to a better understanding of the micropores characteristic of coal.

Abstract: Three novel poly N-phenylene-N-aroylthioureas (2a~c) were synthesized by the reaction of aryldiamines with terephthaloyl diisothiocyanate. Their structures were characterized by IR spectra and ¹HNMR. The preliminary biological activity tests showed that some compounds display effect in growth regulation of plants and fungicidal activity to some extent. The compound 2b has obvious growth promoting effect on Oryza sativa L.(rice), the growth promoting rate to 59.05% and 71.81% in the concentration of 10 mg·L^-1 and 100 mg·L^-1 respectively, and it has obvious inhibition to Echinochloa crusgalli L.(barnyard grass), the inhibition rate of more than 75% in the concentration of 0.1~100 mg·L^-1, and it has weak inhibition for the growth of Cucumis sativus L.(cucumber). The compound 2a has excellent crop safety and 2b has well selectivity for the test plants.

Abstract: A servo hydraulic driving mechanism was designed using servo-tube control principle, this mechanism can move continuously and position accurately. The three-dimensional flow field of the drive cylinder is calculated and analyzed. The results indicate that the driving mechanism can effectively control the differential pressure of the system by changing the gap of the variable throttle orifice, the diameter of servo-tube is as small as possible. When the gap of the variable throttle orifice is less than a certain millimeter, the control effect is more obvious.

Abstract: We set up one cylinder of CNG engine by using GT-Power software and the compression ratio and the knock are studied. The conclusions are as follows: when the compression ratio increases, the rate of pressure rise of acute burning period increases; The maximum cylinder pressure increases; The maximum temperature decreased slightly and after burning period the temperature increases; The critical knocking compression ratio appears at the full load of 4000rpm conditions; If we only consider it knocking or not, the engine compression ratios can change from 10 to 11.