新型哈氏合金G—30的耐蚀性能与工业应用

文章叙述了新型镍基耐蚀哈氏合金G-30在不同介质中的耐蚀性能以及工业应用,综合分析了该合金应用的经济性及前景。     

W片二向色性角β测定中的两个问题

本文讨论在测定W片二向色性角β的实验装置中的两个问题:W片的e轴与起偏器P_1透振方向间夹角θ偏离45°时引起的误差;起偏器P_1、检偏器P_2的消光比ρ对测量精度的影响。     

SAW滤波器简化衍射频响的计算方法

提出了由一个变迹ＩＤＴ叉指换能器和一个均匀ＩＤＴ组成的ＳＡＷ滤波器简化衍射频响的计算方法，即将均匀ＩＤＴ简化成单根指计算其衍射频响。该方法与未简化衍射频响的计算方法相比，计算量大为减小，前者约为后者的（Ｎ为均匀ＩＤＴ的指对数）。并给出了一个实例，用未简化与简化方法分别计算了其衍射频响，结果表明，两者符合得较好。     

A new boundary integral equation for notch problem of plane elasticity

A new boundary integral equation for the notch problem of plane elasticity is formulated in this paper. In the formulation, the distributed dislocation density is taken to be the unknown function and the resultant force function to be the right-hand term in the resulting integral equation. As a result the integral equation derived contains a logarithmic kernel. The equation is compact in form and convenient for computation. The accuracy of the method is demonstrated through a number of numerical examples.     

Design model and guidelines for n-well guard ring in epitaxial CMOS

This work reports the development of design model for n-well guard rings in a CMOS process utilizing a low-doped epitaxial layer on a highly doped substrate. The validity of the model has been judged by a wide range of experimental data measured from the fabricated n-well guard ring structures with guard ring width as parameter. From the model developed, guidelines have been drawn to minimize the guard ring width while critically suppressing the amount of electrons escaping from the guard ring     

InGaAs/AlAs/InGaAsP resonant tunneling hot electron transistorsgrown by chemical beam epitaxy

InP-based resonant tunneling hot electron transistors (RHET's) were studied systematically using chemical beam epitaxy (CBE) for the first time. All the RHET's studied have a highly strained AlAs/In_0.75Ga_0.25As/AlAs resonant tunneling double barrier as a hot electron injector, and an InP collector barrier with or without InGaAsP graded layers. The highest transport ratio (α) observed is 0.98, and the highest peak-to-valley current ratios (PVR's) measured are 20 and 200 in the collector current and base current, respectively, at 80 K. A self-consistent simulation is used as a reference to optimize the hot electron injector and to explain the ballistic transport. An energy spectrometer technique was applied to the RHET's for resolving the hot electron energy distribution which showed a full width at half maximum (FWHM) of around 58 meV, indicating ballistic transport of electrons. Finally, room temperature transistor action was also observed with a β of 4 and a cutoff frequency of 31 GHz     

Load-capacity interference and the bathtub curve

Load-capacity (stress-strength) interference theory is used to derive a heuristic failure rate for an item subjected to repetitive loading which is Poisson distributed in time. Numerical calculations are performed using Gaussian distributions in load and capacity. Infant mortality, constant failure rate (Poisson failures), and aging are shown to be associated with capacity variability, load variability, and capacity deterioration, respectively. Bathtub-shaped failure rate curves are obtained when all three failure types are present. Changes in load or capacity distribution parameters often strongly affect the quantitative behavior of the failure-rate curves, but they do not affect the qualitative behavior of the bathtub curve. Neither is it likely that the qualitative behavior will be affected by the use of nonGaussian distributions. The numerical results, however, indicate that infant mortality and wear-out failures interact strongly with load variability. Thus bathtub curves arising from this model cannot be represented as simple superpositions of independent contributions from the three failure types. Only if the three failure types arise from independent failure mechanisms or in different components is it legitimate simply to sum the failure rate contributions     

Two's complement quantization in orthogonal biquad digital filters

A special class of complex biquad digital filters called orthogonal filters are investigated for stability under two's complement quantization. A sufficient condition is derived for the asymptotic stability of the nonlinear filter. Bounds on the possible limit cycles are also obtained. Using these bounds, any given filter can be tested for stability. The stability triangle is then scanned using a dense grid, and each point on the grid is tested for stability/limit cycles. By this method, the stability region given by the sufficient condition is extended. Regions within the linear stability triangle where various types of limit cycles are possible are also identified.