Notice of RetractionThe temperature modeling of the moving armored vehicle based on finite element method
Due to the decline of the viability and battle effectiveness of the electronic countermeasure armored vehicle caused by intense infrared radiation (IR), the temperature model is built for the IR characterizations of moving target. While taking the effect of radiation, convection and heat transfer into consideration, the mathematic description and simulation of the temperature model are carried out with finite element method (FEM) in the processes of sub-domains partition, node determination, control equation construction, boundary condition determination, equation discretization and iterated calculation. The comparison and analysis of the temperature distribution of typical parts between the simulated results of the FEM and the actual measured value are carried out with the same parameters. It indicates that the results with the application of the FEM approaches the actual measured value more with a better precision.
Atmospheric transparency′s effect on ground target′s infrared character
Atmospheric condition is an important factor to influence the ground target infrared character.After the circumstance factors to influence the target surface temperature are analyzed,the atmospheric transparency′s effect on ground target′s temperature is mainly discussed and the atmospheric effect to attenuate the infrared radiation is also simply discussed.Finally,the two effects are combined to analyze the atmospheric transparency′s comprehensive effects on infrared radiation character of ground target.The result indicates that although the high atmospheric transparency can reduce the target surface temperature in daylight,because of the atmospheric attenuation to infrared radiation,the overall effect is that the higher the atmospheric transparency is,the more intensive the target radiation received by space infrared detector is.
Ultrathin Wafer Pre-Assembly and Assembly Process Technologies: A Review
Ultrathin silicon wafer technology is reviewed in terms of the semiconductor applications, critical challenges, and wafer pre-assembly and assembly process technologies and their underlying mechanisms. Mechanical backgrinding has been the standard process for wafer thinning in the semiconductor industry owing to its low cost and productivity. As the thickness requirement of wafers is reduced to below 100 μm, many challenges are being faced due to wafer/die bow, mechanical strength, wafer handling, total thickness variation (TTV), dicing, and packaging assembly. Various ultrathin wafer processing and assembly technologies have been developed to address these challenges. These include wafer carrier systems to handle ultrathin wafers; backgrinding subsurface damage and surface roughness reduction, and post-grinding treatment to increase wafer/die strength; improved wafer carrier flatness and backgrinding auto-TTV control to improve TTV; wafer dicing technologies to reduce die sidewall damage to increase die strength; and assembly methods for die pick-up, die transfer, die attachment, and wire bonding. Where applicable, current process issues and limitations, and future work needed are highlighted.