Image Magnification Method Using Joint Diffusion

In this paper a new algorithm for image magnification is presented. Because linear magnification/interpolation techniques diminish the contrast and produce sawtooth effects, in recent years, many nonlinear interpolation methods, especially nonlinear diffusion based approaches, have been proposed to solve these problems. Two recently proposed techniques for interpolation by diffusion, forward and backward diffusion (FAB) and level-set reconstruction (LSR), cannot enhance the contrast and smooth edges simultaneously. In this article, a novel Partial Differential Equations (PDE) based approach is presented. The contributions of the paper include: firstly, a unified form of diffusion joining FAB and LSR is constructed to have all of their virtues; secondly, to eliminate artifacts of the joint diffusion, soft constraint takes the place of hard constraint presented by LSR; thirdly, the determination of joint coefficients, criterion for stopping time and color image processing are also discussed. The results demonstrate that the method is visually and quantitatively better than Bicubic, FAB and LSR.

Quality Evaluation of Diffusion Bonded Joints by Electrical Resistance Measuring and Microscopic Fatigue Testing

Micro-structure related behavior of diffusion bonding joints is a crucial issue in device and reactor fabrication of Micro Chemo Mechanical Systems.However,the previous studies have been focused on the macro mechanical performance of diffusion bonded joint,especially diffusion bonding conditions effects on tensile strength,shearing strength and fatigue strength.The research of interfacial micro-voids and microstructures evolution for failure mechanism has not been carried out for diffusion-bonded joints.An interfacial electrical resistance measuring method is proposed to evaluate the quality of bonded joints and verified by using two-dimensional finite-element simulation.The influences of micro void geometry on increments of resistance are analyzed and the relationship between bonded area fraction and resistance increment is established by theoretical analysis combined with simulated results.Metallographic inspections and micro-hardness testing are conducted near the interface of diffusion bonded joints.For the purpose of identifying the failure mechanisms of the joints,both microscopic tensile and fatigue tests are conducted on the self-developed in-situ microscopic fatigue testing system.Based on the microscopic observations,the mechanism of interfacial failure is addressed.The observation result shows that for 316LSS diffusion-bonded joints,microstructure evolution and effect of micro-voids play a key role in interfacial failure mechanism.Finally,a new life prediction model in terms of the increment of electrical resistance is developed and confirmed by the experimental results.The proposed study is initiated that constituted a primary interfacial failure mechanism on micron scale and provide the life prediction for reliability of components sealed by diffusion bonding.

等径角挤压层状复合材料的扩散连接（英文）

研究了等径角挤压层状复合材料的微观组织、扩散和机械结合行为以及显微硬度分布。在室温和高温(300°C)下采用1～4道次等径角挤压工艺制备Al-Cu和Cu-Ni层状复合材料。扫描电镜微观结构表征及抗剪强度试验结果表明,由于在等径角挤压过程中具有更高的塑性变形容忍度,4道次等径角挤压试样层片材料之间的结合强度远远高于1道次样品。此外,剪切强度数据表明,升高等径角挤压温度会使试样的剪切强度显著增加,这主要是由于Al/Cu和Cu/Ni界面在高温下形成了扩散连接。等径角挤压Cu/Ni/Cu复合材料的高温剪切结合强度明显高于等径角挤压Cu/Al/Cu复合材料。

焊点金属间化合物生长的相场法模拟

采用相场法并结合热-力-电-扩散强耦合理论,研究了铜/锡/铜焊点金属间化合物(Intermetallic Compounds,IMCs)的生长规律。其中,铜和锡交互扩散的行为是通过引入铜和锡在不同浓度(摩尔分数)下的扩散系数和有效电荷数来表征。模拟结果表明强耦合状态下的IMCs生长模拟值与实验值吻合较好,并且电流密度越大,IMCs生长越快。此外,对不同耦合状态下IMCs生长的各热力学驱动力的变化研究表明焊点在多物理场作用下,温度梯度导致的热迁移对IMCs生长的影响较小,而应变梯度导致的应力迁移对IMCs生长的影响较大,并且起促进作用。