塑料的EMI／RFI屏蔽

本文综述了防止电磁干扰和无线电频率干扰的塑料涂层的各种方法。当今,占主导地位的是镍基有机导电涂层,但化学沉铜/镍镀层对高性能产品如使用在保密和军事上的计算机更重要。在美国经济界,电子设备中塑料机壳的增长是最快的工业之一,结果使树脂的应用,模具和涂镀设备亦趋于增长。在现代工业趋于下降时,对电磁干扰(EMI)直接的进步取决于屏蔽的需要和装     

Characteristics of natural scenes related to the fractal dimension

Many objects in images of natural scenes are so complex and erratic, that describing them by the familiar models of classical geometry is inadequate. In this paper, we exploit the power of fractal geometry to generate global characteristics of natural scenes. In particular we are concerned with the following two questions: 1) Can we develop a measure which can distinguish between different global backgrounds (e.g., mountains and trees)? and 2) Can we develop a measure that is sensitive to change in distance (or scale)? We present a model based on fractional Brownian motion which will allow us to recover two characteristics related to the fractal dimension from silhouettes. The first characteristic is an estimate of the fractal dimension based on a least squares linear fit. We show that this feature is stable under a variety of real image conditions and use it to distinguish silhouettes of trees from silhouettes of mountains. Next we introduce a new theoretical concept called the average Holder constant and relate it mathematically to the fractal dimension. It is shown that this measurement is sensitive to scale in a predictable manner, and hence, provides the potential for use as a range indicator. Corroborating experimental results are presented.