野草状纳米氧化锌的制备及标准摩尔生成焓

本文采用反相微乳液法制备了尺寸均匀的野草状ZnO纳米结构. 依据热力学势函数法获得了纳米ZnO与块体ZnO标准摩尔生成焓的关系, 并结合微量热技术求得了所制备产物的标准摩尔生成焓, 为研究其它纳米材料的标准摩尔生成焓提供了一种广泛适用的新方法.     

THGEM探测器X光斑寻迹和位置分辨实验研究

介绍了一种基于THGEM的X射线光斑寻迹探测器,用于X射线单光子计量技术研究和测量,探测器有效面积200 mm×200 mm,采用128路基于ASIC和FPGA的高速读出电子学,探测器分为中间高分辨区和外围低分辨区两部分,两部分共用一套读出电子学。实验在中国计量科学研究院利用X光机产生的束线,测试光斑位置、光斑精细分布以及探测器的位置分辨。实验结果表明,探测器实现了同时对光斑寻迹和光斑的精细测量,探测器中间高分辨区x方向的位置分辨率为0.63 mm（FWHM）,y方向位置分辨率为0.62mm（FWHM）,探测器各项性能指标均达到了预期目标。This paper introduces the detector of X-ray spot tracing based on the THGEM. It is used for X ray single photon measurement technology research and measurement with an effective area of 200 mm×200 mm. The circuit board has 128 array of high speed readout electronics based on ASIC and FPGA. And it is divided into two parts:the middle area of high sensitive and the peripheral area of low sensitive. The two parts share a set of readout electronics. The experiment tests the position and the fine structure of the beam line produced by X ray machine in National Institute of Metrology. The results of the experimental show that the detector realizes both the spot tracing and the fine structure of the spot. The position resolution is 0.63 mm in x direction and 0.62 mm in y direction in high sensitive of the detector, which achieve the desired goal of preliminary design.     

一种基于遗传优化的BP神经网络的测光红移估计算法

除了星系的光谱红移之外,星系测光红移的估计也对研究宇宙大尺度结构及演变有着重要的研究意义。利用斯隆巡天项目最新发布的SDSS DR13的150 000个星系的测光及光谱数据,在红移值Z<0.8范围内,先使用SOM自组织神经网络对星系样本进行早型星系和晚型星系的聚类,然后用遗传算法优化后的BP神经网络对星系的测光红移进行估算。估算结果与作为标准的已知星系光谱红移进行比对,早型星系的红移估计最小均方误差约为0.001 3,晚型星系最小均方误差约为0.001 7。实验结果表明,遗传优化的BP算法在精度上优于BP神经网络算法,且效率上优于K近邻、核回归等传统测光红移估计算法。     

全局参数自动估计的彩色图像偏振去雾方法

雾天环境下由于大气粒子对光线的散射作用导致成像质量下降, 针对雾霾等天气下图像退化问题, 提出了一种全局参数自动估计的彩色图像偏振去雾方法。利用不同角度的3幅偏振图像, 自动估算无穷远处的大气光和大气光的偏振度, 根据大气散射模型得到去雾后的图像。从RGB 3个色彩通道分别计算相应的参数, 使得算法适用于彩色领域。首先使用暗通道方法估计无穷远处的大气光和传输图, 并通过导向滤波对传输图优化; 然后基于大气光和目标光的不相关性, 采用全局搜索的方法估计大气光的偏振度; 最后根据大气散射模型恢复出清晰目标图像, 并利用对数变换进行增强。本文方法在雾霾天气下能够得到清晰的去雾图像, 且在浓雾天气下, 去雾图像的信息熵提升了约21%, 平均梯度提升了约2倍多, 标准差提升了约12%。实验结果表明, 本文方法较好地解决了人工取景估计参数不佳的问题, 提高了复原目标图像的清晰度和对比度, 可以用于彩色图像的目标探测与识别。     

一种改进Census变换与梯度融合的立体匹配算法

针对现有立体匹配算法对噪声敏感、易失真、在视差不连续区域与弱纹理区域误匹配率高的问题,提出一种改进Census变换与梯度融合的多尺度立体匹配算法。采用支持窗口内所有像素的加权平均灰度值作为Census变换的参考值,将Census代价与由水平和垂直方向归一化结合的梯度代价进行加权融合,通过设置噪声容限获得稳定的代价,提高了单像素匹配代价的可靠性;在多分辨率尺度下,采用改进引导滤波算法完成对匹配代价的聚合;通过视差提取获得视差图。实验结果表明,该算法在Middlebury测试平台上对标准立体图像对的平均误匹配率为4.74%,对27组扩展立体图像对的平均误匹配率为8.67%。该算法使得视差不连续区域与弱纹理区域的误匹配率进一步降低,且对噪声和光照等干扰表现出较好的稳健性。     

名义上无水硬玉矿物中“水”的热变异行为研究

以硬玉岩中名义上无水硬玉矿物为研究对象,通过常温和变温红外光谱测量,确定硬玉矿物结构水表征及变温过程热变异行为。研究结果显示：由M-OH伸缩振动所致的红外吸收谱带集中于3 700～3 600,3 570～3 520,3 500～3 300及3 230～3 140 cm-1波数范围内,但在不同的硬玉岩中具有不同的红外吸收。变温过程中,该吸收谱带基本在500 ℃左右相对吸收强度出现较为明显的减弱,且结构水含量也逐渐下降,进一步表征硬玉矿物中的“水”是以结构水的形式进入晶格。但此M-OH伸缩振动所致的吸收谱带、结构水含量和指纹谱均在850 ℃附近出现较为明显的变化,预示该温度硬玉矿物的成分已出现变异。硬玉矿物中“水”的热变异行为为进一步了解水分子的赋存状态与结合方式及其成岩机制提供一定的佐证。     

Highly-sensitive NO,NO_2,and NH_3 measurements with an open-multipass cell based on mid-infrared wavelength modulation spectroscopy

A compact prototype based on mid-infrared wavelength modulation spectroscopy(WMS)is developed for the simul-taneous monitoring of NO,NO_2,and NH_3 in the urban area.Three quantum cascade lasers(QCLs)with central frequencies around 1900.0 cm~(-1),1600.0 cm~(-1),and 1103.4 cm~(-1)are used for NO,NO_2,and NH3detections,respectively,by timedivision multiplex.An open-path multi-pass cell of 60-m optical path length is applied to the instrument for high sensitivity and reducing the response time to less than 1 s.The prototype achieves a sub-ppb detection limit for all the three target gases with an average time of about 100 s.The instrument is installed in the Jiangsu environmental monitoring center to conduct performance tests on ambient air.Continuous 24-hour measurements show good agreement with the results of a reference instrument based on the chemiluminescence technique.     

Optical waveguide in Nd:Bi_(12)SiO_(20) crystal produced by multi-energy C ion implantation

We report the fabrication of a planar waveguide in the Nd:Bi_(12)SiO_(20) crystal by multi-energy C ions at room temperature. The waveguide is annealed at 200℃, 260℃, and 300℃ in succession each for 30 min in an open oven. The effective refractive index profiles at transverse electric(TE) polarization are stable after the annealing treatments. Damage distribution for multi-energy C ion implanted in Nd:Bi_(12)SiO_(20) crystal is calculated by SRIM 2010. The Raman and fluorescence spectra of the Nd:Bi_(12)SiO_(20) crystal are collected by an excitation beam at 633 nm and 473 nm, respectively. The results indicate the stabilization of the optical waveguide in Nd:Bi_(12)SiO_(20) crystal.     

晶核剂P2O5对CaO-Al2O3-SiO2系黄磷炉渣微晶玻璃析晶的影响

采用熔融法以自然冷却黄磷炉渣为主要原料,P2O5为晶核剂,制备了黄磷炉渣微晶玻璃.利用X射线衍射仪(XRD)、差热分析(DTA)和扫描电子显微镜(SEM)等分析技术手段,探究了晶核剂P2O5(以KH2PO4的形式引入)对黄磷炉渣微晶玻璃晶化行为及物化性能的影响规律.结果表明:黄磷炉渣基础玻璃的析晶峰温度Tp及析晶活化能E随着P2O5晶核剂的增加呈现先减小后增大的趋势;当晶核剂P2O5加入量达到4wt;时,黄磷炉渣基础玻璃的析晶峰温度Tp及析晶活化能E最小,析晶效果最优,物化性能最优;主晶相硅灰石(CaSiO3)并不随着晶核剂P2O5加入量的增大而发生改变,同时能够促进晶相氟磷灰石(Ca5(PQ)3F)生成.     

木质素催化转化制备异丙苯

Cumene is an important intermediate and chemical in chemical industry.In this work,directional preparation of cumene using lignin was achieved by a three-step cascade process.The mixture aromatics were first produced by the catalytic pyrolysis of lignin at 450℃ over 1% Zn/HZSM-5 catalyst,monocyclic aromatics with the selectivity of 85.7 wt% were obtained.Then,the catalytic dealkylation of heavier aromatics resulted in benzene-rich aromatics with 93.6 wt% benzene at 600℃ over Hβ catalyst.Finally,the cumene synthesis was performed by the aromatic alkylation,giving cumene selectivity of 91.6 C-mol% using the[bmim]Cl-2AlCl₁₃ ionic liquid at room temperature for 15 min.Besides,adding a small amount of methanol to the feed can efficiently suppress the coke yield and enhance the aromatics yield.The proposed transformation potentially provides a useful route for production of cumene using renewable lignin.