Decoherence of matter waves by thermal emission of radiation

Emergent quantum technologies have led to increasing interest in decoherence--the processes that limit the appearance of quantum effects and turn them into classical phenomena. One important cause of decoherence is the interaction of a quantum system with its environment, which 'entangles' the two and distributes the quantum coherence over so many degrees of freedom as to render it unobservable. Decoherence theory has been complemented by experiments using matter waves coupled to external photons or molecules, and by investigations using coherent photon states, trapped ions and electron interferometers. Large molecules are particularly suitable for the investigation of the quantum-classical transition because they can store much energy in numerous internal degrees of freedom; the internal energy can be converted into thermal radiation and thus induce decoherence. Here we report matter wave interferometer experiments in which C70 molecules lose their quantum behaviour by thermal emission of radiation. We find good quantitative agreement between our experimental observations and microscopic decoherence theory. Decoherence by emission of thermal radiation is a general mechanism that should be relevant to all macroscopic bodies.     

多路单色光源水分测量方法的研究

提出了一种基于多次透射反射积分球单色光源水分测量的方法.利用多次透反射积分球测量水分,可以提高仪器的测量精度.设计出了四种不同波长的单色红外光的发射、检测光路,四个不同单色发光波长的红外光源按照不同的角度放置,使它们发出的单色红外光交叉于被测物的同一点上,达到了同点检测的效果,提高测量的准确性.选择标准单色近红外光源,用此光源可以省去卤钨灯、滤光轮、准直聚焦器、电机等设备,特别是省去了笨重的冷却系统,大大减小了仪器体积,降低了成本.四只单色红外光源采用一个脉冲电源供电,保证其同步工作.     

室内LED光源的光生物安全分析

为评估室内LED光源潜在的光生物安全风险,搭建了光生物安全测试系统平台.在该系统平台上对常用的几款室内LED光源进行了较全面的光生物安全测试.并对照标准GB /T 20145—2006《光源和光源系统的光生物安全》的要求,对实验结果作了较为详细的分析,对该光源的危险类别做了判定划分.该报告分析对搭建室内LED产品的光生物安全性测试系统以及研究其测试方法均具有一定的参考意义.     

白光散斑的部分相干光理论及其应用

从相干光理论出发，讨论了白光的部分相干性，据此进行了条形刚性浅理基础下地基位移的白光散斑测量。     

利用部分相干效应获得局域空心光束

研究一种特殊的部分相干光束经透镜聚焦后,在几何焦点附近的三维光强分布.结果表明,几何焦点附近的聚焦光强分布不仅依赖于入射部分相干光的光强分布,还依赖于入射光的空间相干度.据此,可以通过选择合适的空间相干度,产生部分相干局域空心光束.此外,还研究入射部分相干光束的相干度和菲涅耳数对局域空心光束的影响.结果显示,对于相干度一定的部分相干光束,当菲涅耳数小到一定程度时,部分相干局域空心光束的现象将消失.     

Blue light emission of porous silicon subjected to RTP treatments

Porous silicon samples were treated with the rapid thermal process (RTP) under different circumstances (N2, Ar, O2 and Air). Before and after treatments, the samples were checked by means of photoluminescence (PL) spectroscopy and Fourier transform infrared spectroscopy (FTIR). Four blue light emission peaks were found in the PL spectra of porous silicon samples subjected to the RTP treatments at temperatures above 400℃. The peak positions were found not to vary with the circumstances and temperatures of RTP treatments. It is considered that due to oxidation during the RTP treatments, the pole size of Si crystal in porous silicon decreased, resulting in the blue shift of light emission. Correlated with the Si crystal sizes discontinuous hypothesis and previous researchers' theory calculation, the PL peak positions did not vary with the RTP temperature and circumstances.     

用相干功率谱对噪声源诊断

本文提出在多振源工况下用相干功率谱辨识噪声源方法;对被识别出的声源进行自谱和倒功率谱分折,能为工厂指明产生噪声的关键设备和具体降噪措施     

轻质复合保温墙板的性能与应用

介绍了轻质复合保温墙板的原材料、生产工艺、产品性能、施工方法及工程应用实例.     

The application of the microstructured metallic grating to light emission extraction

Microstructured metallic gratings can be used to enhance the light emission efficiency of LEDs,and the spectral radiation properties of the LEDs vary with the different metallic materials used,leading to variation of the light emission enhancement at the same wavelength for different metallic grating materials.In this paper,the finite difference time domain(FDTD) method has been used to investigate the light emission extraction enhancement of LEDs in which gratings with different metallic materials have been applied.Through analysis of the permittivity of the metals and the quality factors of the surface plasmons(SPs),we concluded that the larger the plasma frequency obtained for the metallic interband transition,then the more suitable the metals are for light emission extraction of photons with relatively short wavelengths.This is because of the abundance of free electrons in the metals with large plasma frequencies.We also found that the wavelength-dependent trends of the extraction enhancement resulting from the scattering mechanism for different metallic materials are similar to each other.For SP-induced enhancement,either the enhancement peak position or the peak value changes significantly with the different metals.     

不同光源及显色背景下红-黄色翡翠的质量分级

从色度学角度出发,基于CIE 1976L~*a~*b~*均匀色空间,在D_(65)光源、 CWF光源和A光源照射下对红-黄色翡翠样本的L~*、a~*、b~*值进行测量,计算出彩度值C~*.并结合统计分析证明A光源为红-黄色翡翠的最佳照明光源, D_(65)标准照明光源可作为红-黄色翡翠的最佳评价光源.选取与标准光源箱表面灰度相同的孟塞尔中性背景N7色卡为最佳显色背景.实验结果表明,在D_(65)光源与N7色卡背景下,通过K-means聚类分析,最终可将翡翠红-黄色分为七级.     

钢包耳轴活性缺陷声发射信号特征与定位分析

钢包耳轴是整个钢包结构的关键部位之一,耳轴根部在长期的高温吊拉作业中会产生活性疲劳裂纹.针对常规超声法难以对耳轴根部焊缝进行无损检测的问题,提出基于声发射(Acoustic emission, AE)平面定位技术对钢包耳轴根部焊缝活性缺陷进行检测的方法.对原始AE数据进行滤波处理并结合小波包变换对信号进行分析.实验结果表明该方法能够较准确定位焊缝活性缺陷的位置.经过小波包对AE信号进行3层分解与重构后,活性缺陷AE信号频带主要分布在62.5~125 kHz,其能量占总能量的81.25 %,符合一般裂纹扩展的频率特征.     

功率型发光二极管芯片的温度场与应力场

发光二极管(LED)的结点温度和应力分布对它的发光效率、可靠性和寿命有着至关重要的影响。为了优化器件的性能,该文利用有限元方法对功率型LED芯片在不同输入功率、基板材料、换热条件下的温度和热应力进行了模拟与分析。结果表明,目前广泛应用的Sapphire基板效果不是很好,如果能减小晶格不匹配的影响,采用硅基板是较好的选择。当基板导热系数、换热系数大于一定值后,单纯的改进基板的导热系数或强化基板换热,对提高器件的性能已经没有明显的效果。     

Damage evolution and failure mechanism of thermal barrier coatings under Vickers indentation by using acoustic emission technique

Acoustic emission(AE) technique was adopted to monitor the damage evolution of air plasma-sprayed(APS) yttria-partially-stabilized zirconia(YSZ) thermal barrier coatings(TBCs) during instrumented indentation testing, and then the failure mechanisms were investigated by cluster analysis and wavelet transform methods.The results of cluster analysis showed that there were three classes associated with distinct failure types for the 8YSZ coatings under Vickers indentation. Based on wavelet transform, these three clusters could be clearly distinguished from their dominant frequency bands, which were concentrated on levels A5(0–156.25 kHz), D5(156.25–312.5 kHz) and D4(312.5–625 kHz), respectively. Thus, the failure mechanism of 8YSZ coatings under Vickers indentation could be clarified by the distribution of different failure types in indentation depth. To sum up, as indentation load increases, the 8YSZ coatings can accommodate the indenter by elastic or little plastic deformation, microcracks propagation and then debonding at the splat boundaries. By comparing the distribution of AE signals induced by different failure types in indentation depth for samples with different thermal exposure time, it can be inferred that thermal exposure treatment can accelerate the degradation of APS 8YSZ TBCs.     

功率型发光二极管芯片的温度场与应力场

发光二极管(LED)的结点温度和应力分布对它的发光效率、可靠性和寿命有着至关重要的影响。为了优化器件的性能,该文利用有限元方法对功率型LED芯片在不同输入功率、基板材料、换热条件下的温度和热应力进行了模拟与分析。结果表明,目前广泛应用的Sapphire基板效果不是很好,如果能减小晶格不匹配的影响,采用硅基板是较好的选择。当基板导热系数、换热系数大于一定值后,单纯的改进基板的导热系数或强化基板换热,对提高器件的性能已经没有明显的效果。     

Coherent ecological dynamics induced by large-scale disturbance

Aggregate community-level response to disturbance is a principle concern in ecology because post-disturbance dynamics are integral to the ability of ecosystems to maintain function in an uncertain world. Community-level responses to disturbance can be arrayed along a spectrum ranging from synchronous oscillations where all species rise and fall together, to compensatory dynamics where total biomass remains relatively constant despite fluctuations in the densities of individual species. An important recent insight is that patterns of synchrony and compensation can vary with the timescale of analysis and that spectral time series methods can enable detection of coherent dynamics that would otherwise be obscured by opposing patterns occurring at different scales. Here I show that application of wavelet analysis to experimentally manipulated plankton communities reveals strong synchrony after disturbance. The result is paradoxical because it is well established that these communities contain both disturbance-sensitive and disturbance-tolerant species leading to compensation within functional groups. Theory predicts that compensatory substitution of functionally equivalent species should stabilize ecological communities, yet I found at the whole-community level a large increase in seasonal biomass variation. Resolution of the paradox hinges on patterns of seasonality among species. The compensatory shift in community composition after disturbance resulted in a loss of cold-season dominants, which before disturbance had served to stabilize biomass throughout the year. Species dominating the disturbed community peaked coherently during the warm season, explaining the observed synchrony and increase in seasonal biomass variation. These results suggest that theory relating compensatory dynamics to ecological stability needs to consider not only complementarity in species responses to environmental change, but also seasonal complementarity among disturbance-tolerant and disturbance-sensitive species.     

多热源温度触觉复现装置的设计与实现

设计了一种能提供真实感的、基于物理意义的温度触觉复现设备.首先研究了人体与各种不同材质物体之间接触过程的传热过程,据此设计了一个可通过控制珀尔贴表面温度的变化来模拟这一过程的装置.该装置复现部分是由4个15 mm×15 mm的珀尔贴构成的4个独立热源,在温度控制部分增加了反馈和接触检测电路.系统能实现较高的升降温速率,通过对表面温度实时精确控制,可复现各种不同的温度变化曲线.在此基础上提出了一种创新的、基于温度补偿曲线的方法来模拟人手指触摸不同材质时的感觉.多热源复现装置小巧灵活,将来可方便地集成于机器人灵巧手上.最后,通过一系列的温度触觉复现实验,证明了本装置的有效性.     

Compact sources as the origin of the soft gamma-ray emission of the Milky Way

The Milky Way is known to be an abundant source of gamma-ray photons, now determined to be mainly diffuse in nature and resulting from interstellar processes. In the soft gamma-ray domain, point sources are expected to dominate, but the lack of sensitive high-resolution observations did not allow for a clear estimate of the contribution from such sources. Even the best imaging experiment revealed only a few point sources, accounting for about 50% of the total Galactic flux. Theoretical studies were unable to explain the remaining intense diffuse emission. Investigating the origin of the soft gamma-rays is therefore necessary to determine the dominant particle acceleration processes and to gain insights into the physical and chemical equilibrium of the interstellar medium. Here we report observations in the soft gamma-ray domain that reveal numerous compact sources. We show that these sources account for the entirety of the Milky Way's emission in soft gamma-rays, leaving at most a minor role for diffuse processes.     

多光源非均匀光照场景的颜色恒常性

针对多光源非均匀光照场景,提出了一种新的颜色恒常性解决方法.首先将场景图像划分成若干较小区域,分别对各区域光源颜色进行估计,然后根据各区域对场景光源颜色的贡献合并为一种复合光源颜色作为场景光源颜色的近似估计,最后通过对角模型重构图像.实验结果表明,扩展的方法能够更好地解决多光源非均匀光照等场景的颜色恒常性问题.