Calibration of Discrete Element Heat Transfer Parameters by Central Composite Design

The efficiency and precision of parameter calibration in discrete element method （DEM） are not satisfactory, and parameter calibration for granular heat transfer is rarely involved. Accordingly, parameter calibration for granular heat transfer with the DEM is studied. The heat transfer in granular assemblies is simulated with DEM, and the effective thermal conductivity （ETC） of these granular assemblies is measured with the transient method in simulations. The measurement testbed is designed to test the ETC of the granular assemblies under normal pressure and a vacuum based on the steady method. Central composite design （CCD） is used to simulate the impact of the DEM parameters on the ETC of granular assemblies, and the heat transfer parameters are calibrated and compared with experimental data. The results show that, within the scope of the considered parameters, the ETC of the granular assemblies increases with an increasing particle thermal conductivity and decreases with an increasing particle shear modulus and particle diameter. The particle thermal conductivity has the greatest impact on the ETC of granular assemblies followed by the particle shear modulus and then the particle diameter. The calibration results show good agreement with the experimental results. The error is less than 4%, which is within a reasonable range for the scope of the CCD parameters. The proposed research provides high efficiency and high accuracy parameter calibration for granular heat transfer in DEM.

ANALYSIS AND PREDICTION OF INTERFERENCE IN ASSEMBLING CURVED BEVEL GEARS

The phenomena of interference in the course of assembling curved bevel gears are ana. lysed and the corresponding prediction program of interference is established taking KlingInberg bevel gear as an exmple. The factors influencing interferenee are discussed and the coneept ofcritical cutter radius is proposed. Finally, a simplified approximate function between the critical cutter ra- dius and the other factors is derived,and the designing method of avoiding interferenee is provided. The analysis and caiculation are proved to consistent with a case of actual product.

Involvement of unusual noncovalent interactions in the self-assembly of cucurbit[6]uril with [CdCl_4]^(2-) anions

The [CdCl_4]^（2-） anion as a structure inducer has proved to be useful in the construction of cucurbit[n]urilmetal coordination architectures and materials. In order to better understand the role and influence of the structure inducer in Q[n] systems, we report herein the self-assembly of Q[6] solely in the presence of[CdCl_4]^（2-）anions and in the presence of both a linear cationic organic guest and [CdCl_4]^（2-）anions. X-ray diffraction analysis revealed that 1D Q[6] porous channels were formed by the noncovalent interactions between Q[6] and [CdCl_4]^（2-）anions, but the ＇＇honeycomb effect＇＇ was not observed in the present study.However, it seems that the ＇＇honeycomb effect＇＇ and the self-assembly of Q[6] with [CdCl_4]^（2-）anions can be significantly modified and switched in the presence of a linear cationic dibutylamine guest through some unusual noncovalent interactions.