绝对辐射温度计杂散光抑制的仿真分析

绝对辐射温度计可用于高温段热力学温度测量,其滤光片辐射计所接收的信号十分微弱,杂散光将会对实验结果产生一定影响.使用基于蒙特卡罗法的光线追迹模拟软件Trace Pro建立模型进行仿真测试,可以得到因内壁多次反射而产生的杂散光情况.通过安装挡光板和使用高吸收率涂层等方式,可对杂散光进行抑制.本文为减小绝对辐射温度计多次反射杂散光提供了解决思路,并给出了相应的模拟结果.     

昆仑海岸公司 JQAW-5系列管道型CO2变送器

JQAW-5系列管道型CO2变送器采用GE双通道高品质模块．传感器具有吸收镀金反射导光管或波导扩散气体腔室上光线的特有技术。通过光线吸收与CO2浓度成正比例,测量剩余光线并将其转化为一个模拟量信号。     

Si衬底表面圆柱孔形抗反射周期微结构的设计及制造

在本征硅片表面设计并制作了一种圆柱孔形抗反射微结构。基于严格耦合波分析方法,通过数值计算及模拟仿真确定了微结构最优参数组合,设计反射率小于3%。应用二元曝光、湿法腐蚀和反应离子刻蚀技术制作了单面和双面抗反射周期阵列微结构。根据测试结果判断反应气体流量、射频功率及工作气压等工艺参数对微结构形貌及侧壁陡直度具有很大影响,经过实验分析确定了最佳工艺参数组合。采用热场发射扫描电子显微镜和白光干涉仪对该结构进行形貌表征,利用显微成像红外光谱仪对其反射率进行测量。最终结果表明,相比于单面微结构和无结构本征硅片,双面微结构抗反射效果最好,得到反射率为8%左右,基本达到抗反射设计要求。     

边带峰值反射率拟合的光栅特征提取技术

针对高精度测量的要求,探索性地提出了一种多峰值反射率拟合的解调新方法。讨论了Levenberg-Marquardt算法在边波带峰值反射率拟合中的应用。根据光纤布拉格光栅对多波长光源的反射作用,研究光栅反射中心波长与各阶光边波带峰值反射率之间的关系模型,利用Lebenberg-Marquardt算法对光栅反射光谱进行特征提取得到特征参量表征传感信息。初步实验证明了该高精度解调方案的有效性和可行性,并分别获得了0.1℃的温度分辨率和0.5的应变分辨率,对高精度光栅传感系统的研制具有一定的供参考价值。     

复眼原理设计的紧凑式高均匀性光伏聚光器

基于几何光学原理,提出了一种应用于光伏聚光的复眼型聚光器设计方法,实现了在光伏电池上均匀照度分布。该复眼型聚光器由折射曲面、反射平面、自由曲面以及透射平面等四个曲面组成。由边缘光线原理、光线可逆原理、费马原理并结合斜率角控制法得到聚光器轮廓离散点,通过三维建模软件拟合成实体。采用光线追迹软件模拟太阳光入射到复眼型光伏聚光器。结果显示,该复眼型聚光器的几何聚光比为31×,在太阳光正入射时光伏电池表面照度均匀性为98%,平均高度为9.8 mm。     

一种石油生产多分相检测新型光纤传感器研究

为解决石油生产多分相检测问题,研制了一种用于多分相检测的新型双接收端光纤传感器(NDR-FOP),利用ZEMAX光线追迹方法构建了双接收端环形耦合光路(DR-RCOP)模型。对通过NDR-FOP锥形敏感头的光线传输轨迹进行了数学描述与仿真分析。基于研究结果,对油气水多相流混相介质中NDR-FOP多分相检测性能进行了评价以及在实验平台上进行了测试研究,仿真与实验结果均表明:油气水介质之间的差特征值形成了明显的间距,NDR-FOP多分相检测是可行和有效的。     

朗奇光栅法检测自由曲面镜片光焦度

随着以渐进多焦镜片为代表的自由曲面加工技术的出现,传统的光焦度计已经不能满足对于这些镜片的光焦度测量.本文给出了采用朗奇光栅法检测自由曲面眼镜片光焦度的光路结构,并详细介绍了其测量原理.通过光线追迹,对该方法进行了模拟仿真,分析了核心器件朗奇光栅的间距对于测量精度的影响.     

中红外波段仿蛾眼表面高斯面形抗反射微纳结构优化

基于严格耦合波分析理论,设计中波红外波段3~5μm的仿生蛾眼表面高斯面形周期阵列抗反射微纳结构,用三维有限时域差分法进行仿真模拟优化,分析了结构阵列周期、占空比、刻蚀深度对反射率和透过率的影响,比较高斯面形、抛物面形、圆锥形结构模型抗反射效果,给出了最优化参数组合。分析了加工过程中周期、占空比和刻蚀深度以及外部形状轮廓偏差对蛾眼微纳结构的影响,给出了在要求抗反射效果下允许的结构参数公差尺寸范围和建议加工尺寸,结果得到的抗反射结构反射率低于3%~5%,透过率高于90%。     

Dove棱镜的加工误差对耦合损耗的影响

平行光束经过有加工误差的Dove棱镜后,在出射面往往会发生角度倾斜和离轴偏差,从而导致利用Dove棱镜制成的光纤旋转连接器的传输耦合损耗增大。对于Dove棱镜的加工误差在耦合损耗方面的影响,本文利用光线追迹的方法对其进行了理论及模拟分析。分析结果显示,由于加工误差带来的耦合损耗随着Dove棱镜的底角误差及其锥体角误差的增加而增大。而后依据理论结果及光纤旋转连接器的需求,设计加工了5块Dove棱镜,测量了其耦合损耗,并对实验测量值进行了修正,进一步验证了理论的正确性。     

无缝微透镜阵列LED匀光膜研究

本文研究不同孔径无缝微透镜阵列膜LED光线扩散的影响,分析了不同厚度和直径的三角形、四边形和六边形微透镜阵列膜的扩散效果。设计了一种复合曲面微透镜阵列,利用光线追迹方法对其进行模拟,分析微透镜阵列对LED光源发出光线扩散性能的影响。     

通过分流扬声器实现管道噪声控制

提出通过分流扬声器控制管道噪声。首先采用一个干扰扬声器放置在管道的一端作为噪声源,另一个扬声器外接分流电路组成分流扬声器对管道噪声进行控制,并建立管道-扬声器耦合模型。然后设计参数独立可调的分流电路,实现对分流扬声器的固有频率和阻尼比的独立调节,通过优化分流电路的参数,从而使得分流扬声器达到良好的控制效果。最后对所设计的分流扬声器的控制效果进行了数值计算。结果表明:所设计的分流扬声器能够有效控制管道内的声压。与传统的噪声主动控制方法相比,该方法的主要优点在于控制系统不需要误差传感器和控制器,结构简单,实际使用方便。     

引压管路对动态差压检测影响的分析

本应用流体阻抗法的有关理论,分析了动态差压检测系统中引压管路的有关参数对测量动态特性的测量。     

Development of copper beam ducts with antechambers for advanced high-current particle storage rings

There has been continuous progress at the High Energy Accelerator Research Organization (KEK) in R&D on vacuum beam ducts adaptable to future high-current particle storage rings. Here we proposed copper beam ducts with antechambers to deal with the severe issues attributed to the high beam currents. The proposed antechamber scheme can withstand intense synchrotron radiation (SR), provide a beam duct with low beam impedance, and effectively reduce the electron cloud effect (ECE) in positron/proton rings. Several trial models were manufactured by a pressing or cold-drawn method, and assembled with electron beam welding. Special vacuum components, such as connection flanges, distributed pumps, and gate valves, were customized for the beam ducts. TiN coating on the inner surface of the beam duct was also investigated as a mitigating measure for the ECE. Trial models of the copper beam ducts were installed into the KEK B-factory (KEKB), and their performances were evaluated using real positron and electron beams.     

Venting of gas explosion through relief ducts: interaction between internal and external explosions

Relief ducts fitted to venting openings is a widespread configuration in the industrial practice. The presence of a duct has been reported to severely increase the violence of the vented explosion posing a problem for the proper design of the venting device. Several studies have reported the leading importance – in the whole complex explosion phenomenology – of a secondary explosion in the duct. Modern approaches in the study of simply vented explosions (without ducts) have focused on the study of the interaction between internal and external explosion as a key issue in the mechanisms of pressure generation. The issue is even more relevant when a duct is fitted to the vent due the confined nature of the external explosion. In this work the interaction between internal and external events is experimentally investigated for gas explosions vented through a relief duct. The work has aimed at studying mechanisms underlying the pressure rise of this venting configuration. The study has put the emphasis on the mutual nature of the interaction. A larger scale than laboratory has been investigated allowing drawing results with a greater degree of generality with respect to data so far presented in literature.     

Determination of the characteristics of gas-dust flow of exhaust gases from the gas-turbine plant to the reconstructed boilers of the Bereza State District Power Station

Flow of the exhaust gases in intricately shaped gas ducts between the gas-turbine unit and the steam boiler in the steam-gas plant of the Bereza State District Power Station has been investigated. The distribution of the gasdynamic parameters of three-dimensional turbulent flow of exhaust gases in channels of different geometries has been studied. The influence of certain structural elements of the gas duct on the hydrodynamic characteristics of flow has been considered. The amplitude-frequency analysis of the natural oscillations of the gasdynamic parameters in different cross sections of the channel has been performed using fast Fourier transformation. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 79, No. 3, pp. 68–74, May–June, 2006.     

A numerical study of the similarity of fully developed laminar flows in orthogonally rotating rectangular ducts and stationary curved rectangular ducts of arbitrary aspect ratio

 The present study showed that a quantitative analogy of fully developed laminar flow in orthogonally rotating rectangular ducts and stationary curved rectangular ducts of arbitrary aspect ratio could be established. In order to clarify the similarity of the two flows, the dimensionless parameters K _LR=Re/(Ro)^1/2 and the Rossby number, Ro=w _m /Ωd _h , in a rotating straight duct were used as a set corresponding to the Dean number, K _LC=Re/λ^1/2, and curvature ratio, λ=R/d _h , in a stationary curved duct. Under the condition that the value of the Rossby number and the curvature ratio was large enough, the flow field satisfied the `asymptotic invariance property'; there were strong quantitative similarities between the two flows such as in the friction factors, flow patterns, and maximum axial velocity magnitudes for the same values of K _LR and K _LC. Based on these similarities, it is possible to predict the flow characteristics in rotating ducts by considering the flow in stationary curved ducts, and vice versa. Received: 10 September 2001 / Accepted: 13 May 2002     

Classification of simulated hyperplastic stages in the breast ducts based on ultrasound RF echo

Visual inspection of ultrasound is diagnostically limited for characterizing breast tissue, in particular when it comes to visually detecting hyperplasia that forms in the ducts at its early formation (at submillimeter resolution) stages. It can, of course, be seen using biopsies. But this will not be done unless the areas have been flagged using noninvasive modalities. The aim of this paper is to draw to the attention of the medical community (albeit through simulations) that the continuous wavelet transform decomposition (CWTD) that was proven in vivo for tissue characterization before has the potential to flag out simulated hyperplasia data at submillimeter resolutions. And it might be an excellent candidate for detecting in vivo hyperplastic changes in the breast. To the best of our knowledge, this is the first attempt at studying the potential of detecting cell growth in breast ducts using ultrasound. The stochastic decomposition model (the CWTD) of the RF echo with its coherent and diffuse components, yields image parameters that correlate closely with the structural parameters of the (simulated) hyperplastic stages of the breast tissue. The discrimination power of the various parameters is studied under a host of conditions, such as varying resolution, depth, and coherent to diffuse energy ratio (CDR) values using a point-scatterer model simulator that mimics epithelium hyperplastic growth in the breast ducts. These are shown to be useful for detecting the various types of simulated hyperplastic data. Careful analysis shows that three parameters, in particular the number of coherent scatterers, the Rayleigh scattering degree, and the energy of the diffuse scatterers, are most sensitive to variations in the hyperplastic simulated data. And they show very high ability to discriminate between various stages of simulated hyperplasia, even in cases of low resolution and low CDR values. Using the area under the receiver operating characteristics (ROC) curve (A(z)) as the performance metric, values of A(z) > 0.942 are obtained when discriminating between stages for resolution 0.948 for different duct densities.     

Graphitization of inner surface of copper beam duct of KEKB positron ring

In order to evaluate the best technique to reduce electron cloud instability, we measured the electron cloud density in copper ducts coated with titanium nitride and non-evaporable getter used in the KEK B-factory (KEKB) positron ring. In this study, we developed a new system for the graphitization of copper beam ducts. The graphitization of a copper surface by intense electron bombardment resulted in the reduction in the secondary electron yield (SEY) to 1.0 in a laboratory experiment and to 1.1 in a real beam duct. The electron cloud density in the graphitized duct is 30% lower than that in an uncoated copper duct. Thus, it has been confirmed that the graphitization of a beam duct leads to a reduction in the electron cloud density in the duct.     

预留孔道活性粉末混凝土局压性能与承载力分析

以端部局压下预留贯通圆形孔道活性粉末混凝土块体模拟后张预应力活性粉末混凝土结构的锚固区,进行了9个轴心局压试验。发现其开裂与破坏有明显的突然性与一定的脆性:初裂为近似贯穿全高的“中宽端细”侧面纵向裂缝,破坏前裂缝充分发展且不断掉块,破坏时试件劈裂,为先裂后坏的破坏模式。对比试验表明,预留孔道对承压板下楔形体的削弱作用显著,致使局压区侧表面开裂延迟,局压承载力降低。基于试验结果,考虑局压面积比、孔道直径与局压边长比等关键参数影响,提出了预留孔道活性粉末混凝土局部受压承载力实用计算方法。     

A review on the cooling effect of duct-ventilated embankments in China

Duct ventilation, or called air duct, has been used to cool the embankment of the Qinghai–Tibet Railway (QTR). In the past decades, the cooling effect of air ducts has been the subject of numerous investigations, including field observations, innovative designs, and numerical simulations. This review summarizes field observations associated with the cooling effect of air ducts by comparing temperature distributions of duct-ventilated roadbeds with those of earthen roadbeds. Innovative duct designs with temperature-controlled shutters, vertical chimneys, self-adjust windward vents, and overlain crushed-rock layers are assessed in terms of their cooling capacity and constructible feasibility. Numerical method to predict the duct-ventilation embankment temperature is reviewed with the focus on the duct-internal boundary specification. Air convection ducts used in Northern America are compared with ducts applied in China. Some in-service ducts in the QTR's embankment have been plagued with cracking and even failures, calling attentions on the long-term stability of the ducts, especially of reinforced concrete ducts.