Schrödinger uncertainty relation for a quantum oscillator in a thermostat

We introduce the Schrödinger correlator as the holistic characteristic of two types of fluctuation correlations in quantum dynamics and in statistical thermodynamics. We are the first to derive it using methods of thermofield dynamics for the coordinate-momentum variables of a quantum oscillator in a thermostat. We show that the obtained value ensures that the Schrödinger uncertainty relation becomes an equality at all temperatures. We find that the thermal equilibrium for the quantum oscillator has the sense of the thermal correlated coherent state and can be adequately described by a wave function with temperature-dependent amplitude and phase.     

一种改进的SAR图像边缘检测方法

针对Ration边缘提取算法对弱边缘检测效果差，边缘定位精度低的缺点，提出了一种改进算法用于检测微弱边缘，并给出具有FCAR特性的阀值选取办法，实际应用中，将两种方法结合为一种综合处理方法，对真实SAR图像的处理结果表明，该综合处理方法具有较高检测正确率及较好的边缘定位精度。     

一种测量较微弱信号的尝试

本文利用数字锁相放大器原理，提出了改善信噪比的尝试方法。     

A Wiener-Wintner theorem for 1/f power spectra

Wiener's generalized harmonic analysis (GHA) provides a theory of harmonic analysis for subspaces of tempered functions not accessible to the L¹,L², and Fourier series theories; and it does it in a way that is usually more quantitative than that provided by the theory of distributions. On the other hand, GHA does not yield an adequate spectral analysis of large classes of functions, including nonstationary processes and, in particular, 1/f noise. In this paper we adapt GHA to deal with 1/f noise by extending the Wiener-Wintner theorem to the case of 1/f power spectra.     

一种自适应的自动聚焦算法

自动聚焦是图像测量和计算机视觉中的重要技术。研究发现,以前的一些自动聚焦算法,在没有噪声的影响下,效果较好,但一旦有噪声的影响,算法可能会失效,因此,提出了一种自适应的自动聚焦方法。首先通过一个基于局部小窗口的自适应门限将边缘像素和非边缘像素区别开来,然后再加上一个全局门限来进一步滤除噪声的影响,最后用一些自动聚焦算法来计算经过自适应处理后的图像,画出它们的聚焦曲线。经过大量的实验,结果表明,该算法不仅具有单峰性强,无偏性好,灵敏度高等特点,而且还具有很好的抗噪声性能。     

Highway traffic noise prediction using method fully compliant with ISO 9613: comparison with measurements

In this study, we introduce outdoor sound simulation that is fully compliant with ISO 9613 yet with some complementary methods that enhance its applicability; for example, calculation of sound attenuation due to undulating terrain in octave bands, geometric divergence in the near-field of the source, and short-term wind effects. Using the method, we have carried out highway traffic noise prediction and measurement for 12 sites with representative road shapes and structures. In the prediction, the sound power level for a road segment was estimated by the method suggested in ASJ Model-1998 with experimental corrections to the overall noise level and spectrum. Comparing results between predicted and measured noise levels show good correspondence at direct, diffracted and reflected sound fields within 30m from the center of the near side lane.     

Existence and Smoothness of the Density for Spatially Homogeneous SPDEs

In this paper, we extend Walsh’s stochastic integral with respect to a Gaussian noise, white in time and with some homogeneous spatial correlation, in order to be able to integrate some random measure-valued processes. This extension turns out to be equivalent to Dalang’s one. Then we study existence and regularity of the density of the probability law for the real-valued mild solution to a general second order stochastic partial differential equation driven by such a noise. For this, we apply the techniques of the Malliavin calculus. Our results apply to the case of the stochastic heat equation in any space dimension and the stochastic wave equation in space dimension d=1,2,3. Moreover, for these particular examples, known results in the literature have been improved.      

Passive and active interior noise control of box structures using the structural intensity method

This paper presents passive and active vibro-acoustic noise control methods for attenuating the interior noise level in box structures which can be an analogy of cabins of vehicle and aircraft. The structural intensity (SI) approach is adopted to identify the predominant vibration panels and interior noise sources for box structures. In the study, the finite element method is used to determine the structural vibration and structural intensity in the box surfaces. According to structural intensity vectors plot and structural intensity stream lines presentation, the possible effective control positions where the dampers may be attached and the active control forces may act to reduce vibration and interior noise, are identified. From the study, it can be demonstrated that the structural intensity approach and stream line presentation are possible methods for identifying the vibro-acoustic interior noise source and predominant panels which may be modified to reduce the interior noise level. The structural intensity methodology, passive and active noise control results can be extended to the further study of the vibration and interior noise control of actual cabins of vehicles and aircraft.     

基于四阶累计量的固定噪音参量估计

根据高斯噪音高于二阶的累积量为零的特性，提出基于四阶累计量的红外焦平面固定噪音乘性参量估计算法，完成从图象场景中自适应估计阵列单元的增益.利用泰勒级数展开给出乘性参量估计均值和方差的统计特性，证明算法给出乘性增益的估计为渐进无偏估计.提出的算法用蒙特卡罗仿真给予验证，证明了算法的有效性.并将提出的算法应用于实际图象的处理，有效降低了固定图案噪音，达到了较高的非均匀校正水平.     

Ionic noise measurement in polymer electrolytes

Electrical noise associated with ion transport (termed as “ionic noise”) has been measured at different temperatures, using a lock-in amplifier and dynamic signal analyzer for a polymer electrolyte PEO:NH₄I and its CdS dispersed composite. The ionic noise suddenly increases as the polymer passes through its phase transition at T _g and T _m. The T _g-peak in the noise measurement appears more clearly than what it does in DTA/DSC or conductivity measurements. Therefore, we suggest the noise technique as a good probe for studying phase transitions in ion conducting solid electrolytes. Further, the present noise measurements also confirm the known results of DTA/DSC studies that both T _g and T _m of polymer electrolytes shift on the formation of composites.