求解线性不等式组的一个统一算法

本文给出了求解线性不等式组的一个统一算法,此算法包含了松弛方法、Cimmo-型方法:Richardson-型方法、同时投影方法和替代约束方法,同时也讨论了这一算法的分组顺序迭代和平行迭代的实现.     

冷却水流量对CO2空气源热泵气体冷却器换热性能影响的实验研究

以CO_2为工质,对空气源热泵热水器矩形螺旋套管气体冷却器的换热特性进行实验研究,搭建了空气源热泵热水器实验台,测试分析冷却水流量的变化对冷却水进出口温差、CO_2进出口压力与温度、CO_2质量流量、气体冷却器总换热量、总传热系数及热泵系统COP等参数的影响,探究其对气体冷却器换热性能的变化规律。结果表明:随着冷却水流量的增加,冷却水进出口温差、CO_2进出口压力和温度均呈下降趋势,CO_2质量流量则呈上升趋势;气体冷却器的总换热量增加49.70%,总传热系数增加57.55%,COP增加73.41%,增幅较大;而气体冷却器换热效能系数仅增加1.77%,变化趋势不明显。     

Wolter-I型聚焦镜热变形数值研究

为了给聚焦镜热控及支撑结构优化设计提供依据,对爱因斯坦探针项目中的后随X射线望远镜的镜片组进行了三维全尺寸建模与有限元分析.研究了轴向、径向两种温度梯度,以及有、无支撑结构对镜片组形变的影响,并对面形误差与温差范围的关系进行了探究.结果表明:对于无支撑结构,轴向温度梯度下面形误差与半径关系接近线性关系,径向温度梯度下则接近分段二次关系;支撑结构发生热变形时,会使镜片组产生与之对应的面形误差,令同相圆度误差转变为异相圆度误差,并使镜片组整体面型误差峰谷值增加32.25%~123.01%,均方根值增加4.13%~5.14%;对于有支撑结构,热致面形误差与温差成正比,温差每增加1℃,轴向温度梯度下,面形误差峰谷值与均方根值分别增加7.76μm、1.12μm,而对于径向温度梯度则分别增加9.67μm、1.60μm.聚焦镜片热致面形误差在一定情况下与镜片尺寸、温差成线性关系,并受到支撑结构变形的显著影响.     

High sensitivity micro-displacement homodyne interferometry北大核心CSCD

Interferometry is widely used in nano-scale micro-topography measurement. In order to improve its accuracy and sensitivity, a high-sensitivity homodyne interferometry based on white light interference and laser secondary interference was proposed. A high-sensitivity homodyne interferometry system was designed, and the zero point of the laser secondary interference was used to locate the dark striation of white light interference, so that it could reach the maximum slope when optical path difference was zero. The signals of white light and laser were analyzed by using the wave principle and intensity formula of interference fringes, and a sensitivity calculation method based on the combination of white light and laser interference signal was proposed. The system and its sensitivity were simulated. Finally, the optical path was built, and the white light interference fringes were adjusted to the dark striations position, so as to locate the zero position of laser secondary interference and carry out the data acquisition. It is showed that the sensitivity of the measurement method is at least 1 832 times higher than that of the laser secondary interference, and the corresponding measurement uncertainty is only ±0.288 7 mV. The measurement system can effectively solve the problem of large amount of calculation in traditional interferometry, and has high sensitivity, stability and reliability. Copyright ©2022 Journal of Applied Optics. All rights reserved.     

极值温差红外图像的自适应双局部增强算法

针对目前红外焦平面成像系统在观察目标、特别是极值温差目标时,各温度段灰度描述不均匀和细节不够的问题,提出了一种自适应红外图像双局部增强算法。详细介绍了通过空间分布和灰度统计特性两个方向实现对极值温差图像自适应增强的方法,该方法首先从红外图像的空间分布特性出发,将图像切割成多个局部图像,然后再从直方图灰度分布出发,将局部图像的直方图进行聚类分段,并对分段直方图均衡增强,最后对生成的每个局部图像增强结果进行线性插值拼接完成增强算法。通过在红外焦平面系统中实验证明了极值温差自适应的红外图像双局部增强算法的可行性,并获得了很好的效果,成像质量有明显提高。     

Proton irradiation effect on SCDs

The Low Energy X-ray Telescope is one of the main payloads on the Hard X-ray Modulation Telescope satellite.Swept charge devices(SCDs)are selected as detectors for the Low Energy X-ray Telescope.As SCDs are sensitive to proton irradiation,irradiation tests were carried out on the HI-13 accelerator at the China Institute of Atomic Energy.The beam energy was measured to be 10 MeV at the SCD.The proton fluence delivered to the SCD was 3×108protons/cm2over two hours.By comparing the performance before and after irradiation,it is concluded that proton irradiation affects both the dark current and the charge transfer inefficiency of the SCD.The energy resolution of the proton-irradiated SCD is 212 eV@5.9 keV at-60?C,while it before irradiated is 134 eV.Moreover,better performance can be reached by lowering the operating temperature of the SCD in orbit.     

聚集诱导发光

聚集诱导发光(AIE)是唐本忠院士于2001年提出的一个科学概念,是指一类在溶液中不发光或者发光微弱的分子聚集后发光显著增强的现象。高效固态发光的AIE材料有望从根本上解决有机发光材料面临的聚集导致发光猝灭难题,具有重大的实际应用价值。从分子内旋转受限到分子内运动受限,从聚集诱导发光到聚集体科学,AIE领域已经取得了许多原创性的成果。在本综述中,我们从AIE材料的分类、机理、概念衍生、性能、应用和挑战等方面讨论了AIE领域最近取得的显著进展。希望本综述能激发更多关于分子聚集体的研究,并推动材料、化学和生物医学等学科的进一步交叉融合和更大发展。     

An AEE-active polymer containing tetraphenylethene and 9,10-distyrylanthracene moieties with remarkable mechanochromism

A polymer(poly(9,10-anthracenevinylene-alt-4,4'-(9,9-bis(4-(4'-(1,2,2'-triphenylvinyl)phenoxy)butyl)-9Hfluorene-2,7-diyl) dibenzaldehyde), P1) was successfully synthesized through the Wittig-Horner reaction by employing fluorene and 9,10-distyrylanthracene moieties as building blocks for backbone and tetraphenylethenes as pendant groups. Photophysical and thermal properties of the resulting polymeric emitter were fully characterized by ultraviolet-visible(UVVis) absorption and photoluminescence(PL) spectra, thermogravimetric analysis(TGA) and differential scanning calorimetry(DSC). While P1 emits an orange-light centered at 567 nm in dilute tetrahydrofuran(THF) solution, the solid powder of the polymer exhibits strong yellow emission peaked at 541 nm. It is also found that the as-synthesized polymer shows unique property of aggregation-enhanced emission(AEE). In addition, P1 possesses high thermal stability with a decomposition temperature(T_(d,5%)) of 430 °C and high morphological stability with a glass transition temperature(T_g) of 171 °C. Under the stimulus of mechanical force, the emission of P1 can be changed from yellow to red(Δλ_(max)=61 nm), showing a remarkable mechanochromism. The results from XRD analysis suggest that such mechanochromic phenomenonof P1 is probably caused by the destruction of crystalline structure, which leads to the conformational planarization of the distyrylanthracene moieties forming by the polymerization and the increase of molecular conjugation of the backbone.     

Synthesis and characterization of a novel macromolecular surface modifier for polyethylene

A new macromolecular surface modifier, a copolymer of lauryl methacrylate (LMA) and poly(ethylene glycol) methyl methacrylate (PEGMA), was synthesized through free radical polymerization. The copolymer was characterized by nuclear magnetic resonance spectrum (1H-NMR) and thermogravimetric analysis (TGA). The copolymer was used to blend with polyethylene. The binary blends have been characterized by attenuated total reflection/Fourier transform infrared (ATR-FTIR), contact-angle measurements (CDA) and scanning electron microscopy (SEM). The results indicated that poly(ethylene glycol) methyl methacrylate-co-lauryl methacrylate (PEGMA-co-LMA) could diffuse preferably onto the surface of the polyethylene (PE) film, and thus can be used as an efficient surface modifier for PE.     

A digital CDS technique and its performance testing

Readout noise is a critical parameter for characterizing the performance of charge-coupled devices (CCDs), which can be greatly reduced by the correlated double sampling (CDS) circuit. However, a conventional CDS circuit inevitably introduces new noise since it consists of several active analog components such as operational amplifiers. This paper proposes a digital CDS circuit technique, which transforms the pre-amplified CCD signal into a train of digital presentations by a high-speed data acquisition card directly without the noisy CDS circuit, then implements the digital CDS algorithm through a numerical method. A readout noise of 3.3 e^- and an energy resolution of 121 eV@5.9 keV can be achieved via the digital CDS technique.