Measuring and modelling the reflectance spectra of male Swinhoe's pheasant feather barbules

A range of iridescent colour appearances are presented by male Swinhoe''s pheasants'' (Lophura swinhoii) mantle feathers. Two distinct regions of the open pennaceous portion of its feathers display particularly conspicuous angle-dependent reflection. A bright blue band appears in one region at normal incidence that spatially shifts to another at higher illumination angles. The two-dimensional photonic crystal-like nanostructures inside the barbules of these two regions are similar. However, this study found that the spatial variation in their colour appearance results from a continuously changing orientation of barbules with respect to the alignment of their associated barb. A multi-layered rigorous coupled-wave analysis approach was used to model the reflections from the identified intra-barbule structures. Well-matched simulated and measured reflectance spectra, at both normal and oblique incidence, support our elucidation of the origin of the bird''s distinctive feather colour appearance.     

Measurement of Infrared Spectral Directional Hemispherical Reflectance and Emissivity at BNM-LNE

An infrared reflectometer has been designed by BNM-LNE (Bureau National de Métrologie–Laboratoire National d’Essais) to measure the spectral directional hemispherical reflectance of solid materials at ambient temperature. For opaque materials, the spectral directional emissivity can be calculated from the measured reflectance. The reflectance can be measured from 0.8 to 14 μm in five directions with an angle of 12°, 24°, 36°, 48°, and 60° with respect to the normal to the surface of the sample. The optical arrangement to collect the reflected flux is based on the Coblentz arrangement (hemispherical mirror). In fact, four mirrors cut in an hemisphere are used to collect the flux reflected by the sample. This optical arrangement was chosen to limit the angle of incidence of rays on the detector (38° instead of 90° for the Coblentz arrangement). The final expanded uncertainty (level of confidence 95%) of the reflectance is estimated to be about ±0.03 for wavelengths between 0.8 and 10 μm and ±0.04 for wavelengths over 10 μm. The values of the spectral reflectance measured on a black paint and on a white ceramic tile are compared to those measured by the two laboratories PTB (Physikalisch Technische Bundesanstalt) and NIST (National Institute of Standards and Technology). The results validate the measurements performed at BNM-LNE. Paper presented at the Fifteenth Symposium on Thermophysical Properties, June 22–27, 2003, Boulder, Colorado, U.S.A.     

基于方向小波变换的镁熔液弱小气泡检测

运用方向小波的多尺度和多方向变换,对高温镁熔液表面弱小气泡进行检测.先对原始图像进行方向小波变换重构高频,抑制背景杂质,再作帧差和迭代阈值分割处理,最后运用数学形态学检测到弱小气泡,并将结果与传统小波检测进行比较.实验结果表明方向小波变换方法是有效的,而且方向小波更符合图像的方向特点,能够较好地检测出复杂背景中的弱小气泡.     

On the relationship between snow grain morphology and in-situ near infrared calibrated reflectance photographs

Seasonal and permanent snow cover a significant portion of our planet, and its impact on climate is significant. Through specific thermophysical properties, snow controls radiative and turbulent fluxes between the ground and the atmosphere, but many aspects of the energy balance are poorly understood due to lingering uncertainties regarding snow properties, such as grain size in particular. Rapid and accurate measurement method has yet to be developed given the reality of field and laboratory logistical constraints, and the sensitivity of snow to any sort of manipulation.In this paper, we investigate the relationship between snow grain morphology parameters measured from visible (traditional) snow grain photography and optical diameter estimated from Near-InfraRed (NIR) reflectance photographs of snow walls. A total of 51 snowpits were analyzed during our International Polar Year field campaign across a 1000 km South-to-North transect over Eastern Canada. We compared the NIR measurements with the theoretical snow albedo model of Kokhanovsky and Zege (2004). Results show the large difference between the snow specific surface area (SSA) of snow grains derived from snow albedo model and the geometrical (visual) diameter. From three different snow grain classes which can be distinguished from traditional photography, linkages can be made with shape factors required in the optical model in order to retrieve optical grain size from NIR photography.     

物件自动定向原理与方法

对物件的定向原理及方法进行研究,表明决定物件定向的关键因素是定向概率,同时讨论了物件定向的主要方法以及影响定向的其他一些因素。     

机立窑生产线定向拆除爆破

论述了钢筋混凝土框架结构定向拆除爆破的方案,提出了设计中应注意的几个问题.确定了梁、柱、墙的爆破参数以及倾倒过程中的安全距离和安全防护措施.     

定向爆破冷却塔的安全分析及安全防护措施

文章结合冷却塔定向爆破拆除的实例,分别介绍了由爆破引起的爆破飞石、爆破振动、塌落振动、碎碴飞溅和爆破烟尘等爆破安全问题,并对这些问题进行了分析,提出进一步提高爆破安全的技术措施.实践证明,只要安全技术措施得当,各种爆破安全问题是可以得到有效控制的.     

多形貌纳米TiO2的合成、结构和光活性研究

以廉价的、易得的无机含钛盐、氨水以及氢氧化纳等简单原料，以低温水热法合成出一系列的纳米锐钛矿相、板钛矿相以及混晶产品。该工艺具有操作简单易行、干扰因素少、易于工业化生产等优点。TEM结合SEM形貌观察，产品为纳米结构，粒度大小均匀，无团聚，颗粒尺寸20-70nm，且通过实验条件的控制，得到了球状、棒状、羽毛状等多种形貌和不同晶态结构的产品，应用实验表明，产品具有较高的光催化活性，在太阳光下有机染料在60min内脱色率超过96％。     

100m高钢筋混凝土烟囱爆破拆除及安全措施

介绍了在复杂环境中采用控制爆破技术拆除100 m高钢筋混凝土烟囱的工程实例。论述了工程方案的参数设计及主要安全措施。针对烟囱尺寸大、钢筋密、混凝土强度高的结构特点,预先开凿大尺寸导向窗减少了爆破面积。特别针对烟囱爆破中大单耗的特殊情况,为控制爆破飞石采用多层柔性覆盖材料进行近体覆盖防护。通过多角度观察,确认多层柔性材料安全防护有效地控制了爆破飞石。     

羟基磷灰石的形态结晶控制

对化学沉淀法制备羟基磷灰石中的制备温度、pH值、分散剂浓度、反应物浓度以及搅拌速度等因素对羟基磷灰石生长形态和结晶的影响进行了系列研究。结果表明：上述因素分别对HA的生长形态和结晶状况有不同程度的影响．通过对工艺参数的合理选择可以得到具有不同结晶状况和形态的羟基磷灰石颗粒。     

原地塌落与定向倒塌相结合爆破拆除砖烟囱实例

给出了一例砖结构烟囱的爆破拆除工程实例.被拆除烟囱高36 m,底部外径3.50 m,周围环境非常复杂.在烟囱周围沿任何方向的场地均不能满足简单定向爆破所需倒塌长度要求的条件下,采用烟囱上部定向倒塌与烟囱下部原地塌落相结合的爆破方案,成功地完成了该烟囱的爆破拆除任务.并在爆破飞石控制,周围建筑和人员安全防护措施等方面进行了一些新的尝试,取得了一些成功的经验,可对今后类似的爆破工程提供有益的借鏊.     

定向爆破与水压爆破联合拆除水塔的爆破参数选择

从爆炸冲击波的作用时间与水塔的着地时间对比分析入手,讨论了定向爆玻与水压爆破联合拆除水塔的起爆时差和水压爆破用药量,并介绍了一个爆破实例。     

2栋混合结构楼房纵向延时定向倾倒爆破拆除

介绍了2栋砖混结构楼房采用纵向延时定向倾倒爆破拆除。通过采用纵向逐段延时与定向倾倒相结合的爆破设计方案,达到了楼房在爆破倾倒过程中结构充分解体、减小爆破单响药量、降低结构触地振动的目的,同时对采用纵向延时方式与传统的整体定向倾倒方式的爆破振动和塌落振动进行了分析。爆破效果与设计方案吻合,达到预期爆破效果。     

PET光散射薄膜的微观形态调控与光学性能

以聚对苯二甲酸乙二醇酯(PET)为基体、线性低密度聚乙烯(LLDPE)和球形有机硅树脂(SR)粒子为分散相,采用熔融共混法制备了PET/LLDPE、PET/SR、PET/LLDPE/SR三种光散射薄膜,通过模压成型和挤出成型法调控其分散相形态结构,利用扫描电子显微镜和自制的光散射测试平台研究了薄膜的微观形态对其光散射性能的影响。研究表明,所制备的光散射薄膜对光线的散射性能显著,且与微观形态存在紧密联系。     

二维均匀天线阵列空间方向分辨率的研究

利用理论分析和计算机仿真相结合的方法．对三种常用的二维均匀天线阵列（方阵、圆阵、L阵）的空间方向特性进行了深入的理论和仿真实验研究．推导出了三种二维阵列结构的空间方向分辨率的工程近似计算公式,并得到了它们之间的关系;分析了阵元间的互耦对空间方向分辨率的影响,得出了互耦对空间方向分辨率没有影响或影响很小的结论．并对该结论进行了解释;对由工程近似计算得到的空间方向分辨率和计算机仿真得到的实际的空间方向分辨率进行了比较．指出了工程近似计算公式的局限性．     

不同形貌ZnO的制备、表征及8～1μgm红外发射率研究

采用低温水热法，分别用溴化十六烷基三甲基铵（CTAB）和聚乙二醇（PEG-400）作为表面活性剂，合成了具有新颖结构的花瓣状和针状ZnO。采用X射线衍射仪（XRD）、扫描电镜（SEM）对花瓣状、针状以及四针状ZnO样品进行结构、形貌表征，用红外吸收光谱（IR）分析样品的红外吸收特性，通过IR-2型发射率测试仪测试样品在8～14μm波段的红外发射率。测试结果表明，花瓣状ZnO发射率最高，针状其次，四针状最低。利用粒子散射机制对形貌与发射率的关系进行了分析。     

A study of optical reflectance and localization modes of 1-D Fibonacci photonic quasicrystals using different graded dielectric materials

In this paper, we present an analytical study on the reflection properties of light through one-dimensional (1-D) quasi-periodic multilayer structures. The considered structures are as follows: F₇, F₈, F₉, (F₂)¹⁰, (F₃)¹⁰ and some combinations such as: [(F₂)¹⁰ (F₇) (F₂)¹⁰], [(F₂)¹⁰ (F₈) (F₂)¹⁰], [(F₃)¹⁰ (F₇) (F₃)¹⁰], [(F₃)¹⁰ (F₈) (F₃)¹⁰], [(F₂)¹⁰(F₃)¹⁰], [(F₂)¹⁰ (F₇) (F₃)¹⁰] and [(F₂)¹⁰ (F₈) (F₃)¹⁰], where (F_j)ⁿ represents n period of the Fibonacci sequence of jth generation. These multilayer structures are considered of two types of layers. One type of layer is considered of graded material like normal, linear or exponential graded material, and the second type of layer is considered of constant refractive index material. Transfer matrix method is utilized to calculate the reflection spectra and localization modes of such structures in the frequency range 150–450?THz. This work would provide the basis of understanding of the effect of graded materials on the reflection and localization modes in Fibonacci photonic quasicrystal structures and obtained spectra can be used in the recognition of grading of materials. The considered heterostructures provide the broad reflection band and some localization modes in the calculated region.     

铌-硅基超高温合金定向凝固及相组成的热力学研究进展

铌-硅基超高温合金作为有望在1200℃以上温度使用的结构材料而受到广泛研究。综述了铌-硅基超高温合金中合金化元素的作用以及熔体过热处理技术在该合金定向凝固中的应用,并评述了对铌-硅基多元合金相组成等的热力学研究进展。     

Surface morphology, composition and thermal behavior of tungsten-containing anodic spark coatings on aluminium alloy

Anodic spark coatings on aluminium alloy were prepared in aqueous electrolytes with sodium tungstate. The influence of boric acid addition in the electrolyte on the surface morphology, elemental and phase composition of the coatings was investigated. In both cases the coatings contained O, Al and W. The coatings obtained in electrolyte with boric acid and sodium tungstate contain also B at approximately 1 at.%. Scanning electron microscopy indicated that the coatings had three layers: the grey underlayer of anodic alumina, the second black layer of crystalline or amorphous aluminium tungstate agglomerated into fibers and the outer green layer of WO₃. It was proposed that isopoly- and heteropolyanions in the electrolyte used take part in the coating growth.