Evaluation of gap length fluctuation with harmonic analysis method

Gap length (GL) of reading head is one of the most critical parameters for high-density magnetic recording systems. A novel method is proposed for quantitative evaluation of the GL fluctuation among a batch of magneto-resistive/giant magneto-resistive heads with same structure design. The method works at head-gimbal assembly level and the evaluation can be done with any read/write analysis equipment. The testing process is based on harmonic analysis of the readback signal. The testing system consists of a selected reference head and sample heads for evaluation. A GL variation function is introduced for the evaluation of GL deviation between the reference head and sample head. This method proved to be easy for implementation and results suggest that variation of GL is considerable and has obvious effect on recording performance in high recording density systems.     

TDI线扫相机光学通道建模与仿真

卫星相机建模与仿真研究不论在民用还是军事领域都具有重要的理论研究和实际应用价值。根据TDI线扫相机的工作原理建立了一个TDI线扫相机光学通道的数学模型,该模型包括从景物到TDI CCD离散图像的几何投影关系和能量传递关系两部分,对于确定的成像系统,给定景物参数和光学系统参数,就可以确定对应图像传感器上的离散图像。为了验证模型,对一幅卫星图像进行了计算机仿真。建立的模型可以用来研究当成像条件改变时对图像的影响,进一步还可以用来发展虚拟卫星相机系统。     

Technique for Monolithic Fabrication of Microlens Arrays Integrated with Infrared CCD

Based on scalar diffraction theory, 8-phase-level 256×256 elements diffractive microlens array with element dimension of 50×33 μm2 have been fabricated on the back-side of PtSi(3～5 μm) infrared CCD. The measurement results indicated that the ratio of the signal-to-noise of the infrared CCD with microlens was increased by a factor of 2.8.     

Riccati方法与微分方程的渐近积分

考虑二阶常微分方程x″ f(t)x=0,t≥a,(1)假设应用Riccati方法得到方程(1)的主解(principal solution)的一个渐近积分并研究其副解(nonprincipal solutions)的三种不同的渐近性质.主要结果如下:定理1 若(Ⅰ)成立,则方程(1)有解x_1满足及另一解x_2满足x_2(t)=t[1 o(1)]. 反之,若方程(1)有解x(t)→1,t→∞,则(Ⅰ)成立. 定理2 设(Ⅰ)成立.(i)若(Ⅱ)成立,则方程(1)有解x_2使x_2’(t)=1 [tF(t) G(t)][1 o(1)] o(1). (ii) 反之,若方程(1)有解x使x’→1,t→∞,则(Ⅱ)成立. 定理3 若(Ⅲ)和(Ⅳ)成立,则方程(1)有解x_1满足(2)及解x_2满足     

一类广义积分integral from n=0 to ∞(((sin(θ_x))/x)~ndx)的计算

利用三角函数幂公式、L′Hospital法则、分部积分公式,得到含有三角函数的第一类广义积分integral from n=0 to ∞(((sin(θ_x))/x)~ndx)的计算公式,其中n≥1且θ≠0.     

Quantum Phase Transition in Quasi-two-dimensional Heisenberg Antiferromagnet with Single-Ion Anisotropy

In the present paper, we investigate the quantum phase transition in a spatially anisotropic antiferrornagnetic Heisenberg model of S =1 with single-ion energy anisotropy. By using the Schwinger boson representation, we calculate the Gaussian correction to the critical value J⊥^c caused by quantum spin fluctuations. We find that, for the positive single-ion energy, a nonzero value of J⊥^c is always needed to stabilize the antiferromagnetic long-range order in this model. It resolves a difference among literature and shows clearly that the effect of quantum fluctuations may qualitatively change a result obtained by the mean-field theories on lower-dimensional systems.     

Spectral Analysis of Powers of the Operator (Vf)(x)=q(x)∫0 xw(t)f(t),dt

Mathematical Notes -     

On the Similarity between Volterra Operators and Transformation Operators for Integro-Differential Operators of Fractional Order

We establish the similarity between certain Volterra integral operators and the Riemann--Liouville fractional integration operator as well as the existence of a triangular transformation operator for integro-differential equations of fractional order. The results obtained are consistent with similar results for the case of integer order.     

Interpolatory integration rules and orthogonal polynomials with varying weights

We investigate which types of asymptotic distributions can be generated by the knots of convergent sequences of interpolatory integration rules. It will turn out that the class of all possible distributions can be described exactly, and it will be shown that the zeros of polynomials that are orthogonal with respect to varying weight functions are good candidates for knots of integration rules with a prescribed asymptotic distribution.Research supported by the Deutsche Forschungsgemeinschaft (AZ: Sta 299/4-2).     

超大规模集成电路波导光互连技术的现状与前景

介绍超大规模集成电路(VLSI)波导(?)互连技术的最新进展,并预测其发展方向,以及如阿解决存在的实际问题。