3D Monte Carlo Analysis of Discrete Dopant Effects on Electron noise in Si Devices

A preliminary study of velocity fluctuations in simple devices using an atomistic model for the ionized impurity scattering is presented. The velocity fluctuations are responsible for thermal noise in semiconductor devices. In this paper the influence on the spectral density of velocity fluctuations of the boundary conditions, the doping level, the length of the resistors and the excess/default of impurities has been addressed.     

TES microcalorimeter readout via transformer

Readout configuration for Transition Edge Sensor (TES) electrically coupled to a low noise warm front-end via transformer is studied. The study was aimed at the implementation of the readout involved in imaging with microcalorimeter detector arrays using frequency multiplexing technique (Appl. Phys. Lett. 81(1) (2002) 159). A model describing both TES electrothermal reaction and the readout response is investigated. Contribution of electronic noise to TES energy resolution is calculated. Prospective readout architecture with TES electrical biasing from the warm readout side is introduced. The architecture allows building of large imaging detector arrays with TES. It is shown that an unprecedented combination of imaging and spectrometry features can be achieved with TES readout via transformer.     

阀门流场的数值模拟及流噪声的实验研究

采用非结构、非交错网格的有限体积法求解用二方程模型封闭的雷诺平均N S方程组 ,对水管路系统中 3种常见阀门的三维分离流动进行数值模拟。模拟结果表明 ,随着蝶阀、闸阀和球阀开度的减小 ,流体在蝶阀背面、球阀阀门内外分别形成两个方向相反的漩涡 ,闸阀的漩涡出现在挡板与管道的壁角处 ,并且漩涡在阀门下游逐渐消失。同时实验表明 ,阀门下游的流噪声大于阀门上游的流噪声 ,涡声是阀门噪声的主要来源     

Atmospheric effects of friction,friction noise and wear with silicon and diamond. Part II. SEM tribometry of silicon in vacuum and hydrogen

Scanning electron microscope (SEM) tribometric data on polycrystalline silicon (poly-Si) vs. poly-Si, Si(100) vs. Si(100) and Si(111) vs. Si(111) interfaces, obtained in Torr and in 0.2 Torr partial pressure of hydrogen gas ( ) from room temperature to 850^°C, were performed under standard and much slower thermal ramping rates. The friction data were analyzed per the methodology described in part I of this paper series. The results indicate a highly beneficial friction- and wear-reducing regime within a relatively narrow thermal region. This desirable region coincides with some chemisorption of excited species of molecular hydrogen just before the mass thermal desorption of surface hydrides. These data represent the tribochemical equivalent of a method routinely used in electronics, whereby deep electron traps (dangling Si bonds) are passivated by baking in molecular hydrogen. The also exerts a moderating influence on the size of the friction noise at all test temperatures. However, the general level of friction beyond the beneficial thermal region is high. In parallel, the general wear rate of Si representative of the entire range of standard thermal ramping in both atmospheric environments is in the extremely high 10^-12m³/(N m) range. Operating strictly in the beneficial, low-friction thermal regime resulted in a several orders-of-magnitude reduction in the wear rate over those measured under standard thermal ramping conditions. Although the results confirm previous findings that Si is not a good material of construction for miniaturized moving mechanical assemblies (e.g., microbearings and gears), there seems to be some limited possibility of gas-phase lubrication of Si micromechanisms with rarefied hydrogen at surface temperatures between 100 and 300^°C. This revised version was published online in July 2006 with corrections to the Cover Date.     

具有未知系统偏差的自适应Kalman平滑器

提出一种有效的具有未知系统伯差的自适应Ｋａｌｍａｎ平滑器．应用状态空间方法和ＡＲＭＡ新息模型，基于白噪声估值器和输出预报器，给出线性离散定常系统自适应最优状态和偏差联合Ｋａｌｍａｕ平滑器，最后给出仿真实例．     

Simulation of X-ray pulsar signals with multiphysical properties

In view of the few and discontinuous X-ray pulsar data, based on the physical properties of the X-ray pulsar real data from the Rossi X-ray Timing Explorer (RXTE) spacecraft, this paper adopts the fast iterative method and the 10 μs time transformation model, simulates the X-ray pulsar signals which have the periodic property, spectral property, and the background noise property as well as a variety of delay effects. We design and implement simulation software which can simulate the X-ray pulsar signals with multi-physical properties. The results of comparing the real data and simulation data in the same situation show that the simulation noises and the actual noises have the same distribution, that the period stability of the simulated X-ray pulsar data agrees with the real data, with the error of only 0.43％, in different energy levels, that the simulated data's integrated profile and the real data's standard profile are highly correlated with the Pearson correlation coefficient of 0.99, and that under the 10μs time transformation model, the time conversion accuracy of the simulation data can reach 10^-7s, the error between the simulation and the real data being just only 10^-7s, which meets the time transformation accuracy. Therefore, the proposed method can realize the high-fidelity simulations and generate the continuous pulsar signal with many physical properties.     

有色噪声激发下结构随机振动离散分析方法

本文以线性结构体系在白噪声激发下随机振动离散分析方法为基础,对线性结构体系在有色噪声激发下的随机振动离散分析方法进行了研究。给出均值、均方响应的离散递推式.并为了能在计算机上进行实际运算,给出了实用化计算公式,最后用该方法对一结构进行了实际计算,分析了计算结果。     

基于红外焦平面阵列读出结构的非均匀校正算法

空间固定图案噪声严重影响了红外探测器的成像质量,它主要是由于焦平面阵列上各探测单元对于同一辐照的光电响应不完全一致所造成。另外,多通道图像数据采集电路的非均匀性更加重了这种噪声。本文提出了一种基于红外焦平面阵列读出结构的非均匀校正算法,它将校正过程分成两步。首先利用恒定统计方法滤除由通道放大器引起的固定图案噪声,然后再将处理结果通过改进的神经网络方法,进一步校正由探测器响应而产生的非均匀性。由于该算法是递推进行,并且具有收敛速度快、计算复杂度低等优点,因此易于工程实现。文中详细阐述了算法的基本原理及其流程,并用仿真数据和真实红外数据对算法性能进行验证,取得了较好的效果。     

动态核的形态分解联想算法及抗随机噪声研究

在灰度图像分解算法和动态核形态联想记忆网络的基础上,提出了一种新的联想记忆算法--动态核的形态分解联想算法.该方法显著地提高了联想记忆抗随机噪声的能力,较好地解决了灰度图像在含噪时的联想记忆和识别的问题,从而给出了一种恢复含噪灰度图像的途径,并把该方法推广到了彩色图像的处理.通过实验,验证了该方法的良好性能,取得了理想的结果.     

基于多体动力学的汽轮机振动声辐射机理及传递路径

采用多体动力学方法进行汽轮机机械振动激励源精确分析,在激励源分析结果的基础上研究低频激励下的机组振动响应,并采用声传递向量（Acoustic Transfer Vector,ATV）方法研究汽轮机组表面与外场辐射的声压传递贡献量,从多体动力学的角度并结合流固耦合的方法综合分析汽轮机组振动噪声产生机理并研究噪声典型传递路径。研究结果表明,旋转激励源为汽轮机组的主要振动激励源,在低频段汽轮机组辐射模式为单极子,在中高频段汽轮机组辐射模式为偶极子。由噪声辐射的指向性极坐标图可知,在不同高度处噪声指向性相似,并都在长度方向上取得噪声声压级较大值,具有较强的指向性。计算方法对汽轮机组减振降噪研究具有一定的指导意义。