Papers by Keyword: Nonuniformity

Abstract: In this work, p-type thermoelectric material was produced by hot extrusion of pre-synthesized in injection molding machine Bi_0.5Sb_1.5Te₃ solid solution. During the research radial distribution of the Seebeck coefficient was confirmed and described in material’s cross section using thermal measuring probe. Such nonuniformity of the Seebeck coefficient is correlated with the strain-stress state of extrudate specifically with the distribution of accumulated strain intensity, which was obtained by mathematical modeling of extrusion process using the software package DEFORM.

Abstract: Nonuniformity of Infrared Focal Plane Array (IRFPA) has greatly limited the quality of infrared imaging system, so nonuniformity must be corrected before using IRFPA. In order to reduce nonuniformity correction calculating amount and improve real-time nonuniformity correction speed, a new compressing correction method of utilizing hardware memory is presented. In this paper, memory compressing correction principle and implementing process are expounded in detail, and the hardware circuit diagram is given out. The experimental results prove that the method has simple circuit and excellent image quality and it easily realizes real-time nonuniformity correction.

Abstract: The symmetry limit theory for 3-D continua developed by the authors, is applied to predictions of the occurrence limit of nonuniform strain in cylinders subjected to cyclic torsion. Bifurcation analysis of a steady-state path, which was defined as a continuous sequence of steady states generated under continuous increasing amplitude cyclic loading, is performed for the cylinder model. The deformation mode with very short wavelength in the circumferential direction is obtained, analogous to that in the internal buckling of a rigidly confined continuum shown by Biot. It is shown that this circumferential short-wave mode occurs at much smaller amplitude than the bifurcation under monotonic torsion.

Abstract: Chemical mechanical polishing (CMP) has already become a mainstream technology in global planarization of wafer, but the mechanism of nonuniform material removal has not been revealed. In this paper, the calculation of particle movement tracks on wafer surface was conducted by the motion relationship between the wafer and the polishing pad on a large-sized single head CMP machine. Based on the distribution of particle tracks on wafer surface, the model for the within-wafer-nonuniformity (WIWNU) of material removal was put forward. By the calculation and analysis, the relationship between the motion variables of the CMP machine and the WIWNU of material removal on wafer surface had been derived. This model can be used not only for predicting the WIWNU, but also for providing theoretical guide to the design of CMP equipment, selecting the motion variables of CMP and further understanding the material removal mechanism in wafer CMP.