基于量子关联的显微成像研究进展

简要回顾了量子关联成像的基本原理和发展历程,从量子光源和经典光源的角度详细介绍了量子关联成像在显微成像中的研究进展。做出了基于经典源的量子关联成像因易于实施、成本较低,在显微成像中更具应用前景的判断。     

相关噪声背景下加权高阶累积量的时延估计方法

时延估计是双基阵被动定位中的重要问题。在非相关噪声干扰下,应用广义互相关法进行时延估计可以取得良好的估计效果,但在相关噪声干扰情况下其估计性能严重下降。使用高阶累积量进行时延估计,可以有效地去除相关高斯噪声的干扰。采用类似广义互相关加权的方法对高阶累积量进行PHAT加权,进一步抑制噪声的影响,提高了高阶累积量法的估计性能。结果表明,在相关噪声背景下加权高阶累积量时延估计效果优于广义互相关法和高阶累积量法。     

量子关联成像及其雷达应用研究

介绍了量子关联成像的物理原理,阐述了量子关联成像灵敏度高、抗干扰能力强、信息获取效率高、能够实现单像素探测成像和无透镜成像的技术特点;探讨了量子关联成像雷达的运动物体成像问题和大气影响应对问题,指出可通过提高采样频率、升级跟踪手段、优化成像策略等方式提升量子关联成像雷达的应用性能;展望了量子关联成像雷达在侦察、预警等领域的发展方向,提出未来通过发展极弱光条件下的成像技术、优化设计照明方式、建立多基站协同体系、发展人工智能算法和多维信息智能融合算法等方式,进一步提升量子关联成像雷达的发现概率、跟踪精度、判别准确度、有效作用距离。     

Lens-less quantum ghost imaging: New two-photon experiments

New types of lens-less two-photon ghost imaging experiments are described that can also be useful for 3D X-ray imaging. In these experimental setups, a CCD array is placed facing a chaotic light source and gated by a photon counting detector that simply counts all randomly reflected photons from an object. A “ghost” image of the object is then observed from the gated CCD. A ghost image of an object can even be observed when the photon path to the photon counting device is obscured. These interesting demonstrations are not only useful for practical applications, such as X-ray lens-less imaging, but are also important from a fundamental point of view. These demonstrations lead to insight regarding the nonclassical two-photon interference nature of thermal light ghost imaging.     

变流器气动噪声分析与噪声控制研究

为控制某型号变流器噪声,文章对该变流器产品开展柜体内气动噪声仿真研究,并与试验结果对标,验证仿真方法可靠性,并协助进一步诊断噪声问题。仿真研究结果表明:机柜内部气动噪声源主要集中在风机附近区域,由风机叶片旋转引起的离散声源。风机噪声频谱在叶片通过频率及其他谐频出现明显峰值。文中对不同降噪方案进行仿真分析,对比了不同材料及不同厚度方案的降噪效果,并通过试验进行了验证。结果表明,使用吸声材料方案使出口总声压级降低 12.2 dB(A)。仿真分析法的降噪优化量与试验结果相近,该方法可应用于后续新产品的降噪设计。     

太赫兹波计算鬼成像:原理和展望

本文立足于太赫兹波成像领域近年来备受关注的研究热点—太赫兹波计算鬼成像,首先回顾了鬼成像从量子到经典再到计算的历史过程,然后阐述了计算鬼成像的数学原理,随后综述了计算鬼成像在太赫兹波段的发展历程,及其在超衍射分辨成像、石墨烯光电导成像、太赫兹光谱成像等方面的应用,并在最后展望了太赫兹波计算鬼成像的发展前景:计算鬼成像作为一种成像手段,可以绕开在太赫兹频段缺乏经济高效的焦面阵列式探测器的难题,但目前的成像帧率还难以满足快速成像的应用需求,相信在未来随着器件性能的提升和成像算法的优化,其成像帧率可以得到大幅提升。     

A two-channel circuit for protecting a resonant gravitational antenna from correlated non-Gaussian interference

A modernized circuit with a noninertial nonlinear element, a whitening filter and a matched filter, connected in series-parallel, for suppressing correlated non-Gaussian interference at the output of a cryogenic resonant gravitational antenna is considered. The algorithm is based on the use of optimum processing of vector signals. __________ Translated from Metrologiya, No. 5, pp. 3–9, May, 2008.     

Experimental demonstration of Klyshko’s advanced-wave picture using a coincidence-count based,camera-enabled imaging system

The Klyshko advanced-wave picture is a well-known tool useful in the conceptualisation of parametric down-conversion (SPDC) experiments. Despite being well-known and understood, there have been few experimental demonstrations illustrating its validity. Here, we present an experimental demonstration of this picture using a time-gated camera in an image-based coincidence measurement. We show an excellent agreement between the spatial distributions as predicted by the Klyshko picture and those obtained using the SPDC photon pairs. An interesting speckle feature is present in the Klyshko predictive images due to the spatial coherence of the back-propagated beam in the multi-mode fibre. This effect can be removed by mechanically twisting the fibre, thus degrading the spatial coherence of the beam and time-averaging the speckle pattern, giving an accurate correspondence between the predictive and SPDC images.     

Visibility of ghost imaging in a two-arm microscope imaging system

Ghost imaging with a classical thermal source is investigated in a two-arm microscope imaging system. The dependence of the imaging visibility on the aperture of the reference lens is discussed. It is shown that by using large apertures, good visibility as well as enhancing resolution can be obtained. The effects from the distance the object is moved away from the original plane are also studied, and one can obtain good visibility with a well-resolved image by changing the distance.     

汽车空调的气动噪声分析与降噪方案设计

利用数值仿真和试验相结合的方法,开展在研车型空调系统气动噪声的研究。运用宽频噪声源模型和计算气动声学方法(CAA),对某汽车空调系统的气动噪声进行数值模拟,得到空调内部的噪声源分布情况,仿真和试验的频谱变化趋势比较吻合,风量最大偏差为3.5%。给出优化风道型面、改变蜗舌形状、风道包裹吸声棉等降噪措施。     

Quantum analysis of measurement results

It is shown that a stochastic matrix operator (quantum measurement matrix) may be considered in some cases as a density matrix. Results of measurements in the form of figure numbers, interconnected with a matrix of quantum measurements, are similar to quantum observable quantities determined in quantum statistical theory. __________ Translated from Izmeritel’naya Tekhnika, No. 12, pp. 3–8, December, 2006.     

Modeling quantum and structure noise of phosphors used in medical X-ray imaging detectors

The noise properties of granular phosphors used in X-ray imaging detectors are studied in terms of a noise transfer function, NTF. This study is performed in high-exposure conditions where the contribution of structure noise to total screen noise is considerable. An analytical model, based on the cascaded linear systems methodology presented in the literature, is developed. This model takes into account the quantum noise and structure noise. Furthermore, it considers the effect of the K X-rays reabsorption on the phosphor material and the effect of screen thickness on the NTF. The model was validated against experimental results obtained by a set of Zn₂SiO₄:Mn phosphor screens prepared by sedimentation. The model may be used to evaluate the effect of screen thickness and the effect of the characteristic X-rays on NTF in high-exposure conditions where structure noise is considerable.     

The effect of sampling rate on observed statistics in a correlated random walk

Tracking the movement of individual cells or animals can provide important information about their motile behaviour, with key examples including migrating birds, foraging mammals and bacterial chemotaxis. In many experimental protocols, observations are recorded with a fixed sampling interval and the continuous underlying motion is approximated as a series of discrete steps. The size of the sampling interval significantly affects the tracking measurements, the statistics computed from observed trajectories, and the inferences drawn. Despite the widespread use of tracking data to investigate motile behaviour, many open questions remain about these effects. We use a correlated random walk model to study the variation with sampling interval of two key quantities of interest: apparent speed and angle change. Two variants of the model are considered, in which reorientations occur instantaneously and with a stationary pause, respectively. We employ stochastic simulations to study the effect of sampling on the distributions of apparent speeds and angle changes, and present novel mathematical analysis in the case of rapid sampling. Our investigation elucidates the complex nature of sampling effects for sampling intervals ranging over many orders of magnitude. Results show that inclusion of a stationary phase significantly alters the observed distributions of both quantities.     

基于频谱分析的电机噪声源的识别

电机噪声源的识别及控制已成为目前电机行业的一项重要研究。介绍了电机噪声源的分类,并对现阶段常用的噪声源识别方法的优缺点进行了分析和比较。重点分析了利用频谱分析法识别噪声源的基本理论和具体实现。实验表明,频谱分析法可以有效地识别电机噪声源。     

Ultrasmall Near‐Infrared Non‐cadmium Quantum Dots for in vivo Tumor Imaging

The high tumor uptake of ultrasmall near‐infrared quantum dots (QDs) attributed to the enhanced permeability and retention effect is reported. InAs/InP/ZnSe QDs coated by mercaptopropionic acid (MPA) exhibit an emission wavelength of about 800 nm (QD800‐MPA) with very small hydrodynamic diameter (<10 nm). Using 22B and LS174T tumor xenograft models, in vivo and ex vivo imaging studies show that QD800‐MPA is highly accumulated in the tumor area, which is very promising for tumor detection in living mice. The ex vivo elemental analysis (Indium) using inductively coupled plasma (ICP) spectrometry confirm the tumor uptake of QDs. The ICP data are consistent with the in vivo and ex vivo fluorescence imaging. Human serum albumin (HSA)‐coated QD800‐MPA nanoparticles (QD800‐MPA‐HSA) show reduced localization in mononuclear phagocytic system‐related organs over QD800‐MPA plausibly due to the low uptake of QD800‐MPA‐HSA in macrophage cells. QD800‐MPA‐HSA may have great potential for in vivo fluorescence imaging.     

Modeling quantum noise of phosphors used in medical X-ray imaging detectors

The noise properties of the granular phosphor screens, which are utilized in X-ray imaging detectors, are studied in terms of the quantum noise transfer function (QNTF). An analytical model, taking into account the effect of K-characteristic X-rays reabsorption within the phosphor material and the optical properties of the phosphor, was developed. The optical properties of the phosphor material required by the model were obtained from literature, except for the optical diffusion length (σ) that was determined by data fitting and was found to be 26 cm²/g. The deviation between theoretical and experimental data is σ depended. Specifically for σ=26 cm²/g and σ=25 cm²/g the respective deviations between experimental and predicted results were 0.698% and −1.597%. However for relative differences in σ more than 15% from the value 26 cm²/g, the corresponding deviations exceed by 6 times the value of 0.698%. The model was tested via comparison to experimental results obtained by a set of Y₂O₃:Eu³⁺ phosphor screens prepared by sedimentation. The model may be used to evaluate the effect of screen thickness and irradiation geometry on quantum noise of phosphor materials for transmission and reflection mode.     

Biocompatible Semiconductor Quantum Dots as Cancer Imaging Agents

Approximately 1.7 million new cases of cancer will be diagnosed this year in the United States leading to 600 000 deaths. Patient survival rates are highly correlated with the stage of cancer diagnosis, with localized and regional remission rates that are much higher than for metastatic cancer. The current standard of care for many solid tumors includes imaging and biopsy with histological assessment. In many cases, after tomographical imaging modalities have identified abnormal morphology consistent with cancer, surgery is performed to remove the primary tumor and evaluate the surrounding lymph nodes. Accurate identification of tumor margins and staging are critical for selecting optimal treatments to minimize recurrence. Visible, fluorescent, and radiolabeled small molecules have been used as contrast agents to improve detection during real‐time intraoperative imaging. Unfortunately, current dyes lack the tissue specificity, stability, and signal penetration needed for optimal performance. Quantum dots (QDs) represent an exciting class of fluorescent probes for optical imaging with tunable optical properties, high stability, and the ability to target tumors or lymph nodes based on surface functionalization. Here, state‐of‐the‐art biocompatible QDs are compared with current Food and Drug Administration approved fluorophores used in cancer imaging and a perspective on the pathway to clinical translation is provided.     

基于改进量子遗传算法的有源噪声控制方法

提出了一种基于改进量子遗传算法的格型IIR滤波器结构的有源噪声控制方法——改进的量子遗传算法（IQGA）。其核心是在对量子门更新过程进行改进的基础上，引入群体灾变和自适应搜索网格的策略。IQGA不仅收敛速度快，还可以改变基本遗传算法（GA）的局部搜索能力，克服基本遗传算法存在的未成熟收敛问题。仿真结果表明，该算法可以有效地实现噪声控制。     

Correlation between 1/f noise and semiconductor laser degradation

The origin of the increase in residual spectral linewidth during device degradation is experimentally and theoretically clarified in a multiple quantum well (MQW) distributed feedback (DFB) laser. Non-radiative recombination current increases during device degradation and causes 1/f noise to increase. This current 1/f noise is the origin of the increase in the residual spectral linewidth. Through these degradation behaviours, a model showing a correlation between 1/f noise and the semiconductor laser degradation is proposed.     

量子引力场中纳米颗粒的量子理论

首次给出纳米颗粒哈密顿量的明确表示。根据纳米颗粒的量子自旋特性,得到纳米颗粒质量随时间变化的规律。根据纳米颗粒哈密顿量的守恒条件,得到纳米颗粒的量子平动动量、纳米颗粒的量子转动动量、纳米颗粒所受的量子引力及纳米颗粒与纳米颗粒引力中心的量子距离随时间变化的规律。证明纳米颗粒的量子平动动量、纳米颗粒与纳米颗粒引力中心的量子距离、纳米颗粒的量子能量均与颗粒所处的量子状态有关。对于不同量子状态的纳米颗粒,上述物理量的取值不同。本文中创新一组满足对易关系互为共轭的复量子数算符,建立纳米颗粒的量子算符代数理论,得到纳米颗粒能量的量子化表示。