Luminescence characterisation of alumina substrates using cathodoluminescence microscopy and spectroscopy

Polycrystalline alumina (Al₂O₃) substrates, found in many electronic devices and proposed as dosemeters in emergency situations, were invstigated using a scanning electron microscope (SEM) equipped with cathodoluminescence (CL) and elemental analysis probes. The characteristics of the CL spectra, surface morphology, and impurity content of the Al₂O₃ substrates were examined and compared with those of single crystal dosimetry-grade Al₂O₃:C. Whereas the CL spectrum, measured from 250 to 800 nm, for the Al₂O₃:C, contained resolved bands located at ∼340 nm and at ∼410 nm, the spectrum measured with the Al₂O₃ substrate was significantly broader, extending from ∼250 to ∼450 nm, and also included a narrow band at 695 nm. While it is likely that the accepted model of recombination at F⁺ (∼340 nm) and F (∼410 nm) in Al₂O₃:C also applies to the substrate, it is suggested that the presence of impurities within the alumina give rise to additional recombination centres. The 695 nm emission has been assigned to a Cr³⁺ ion impurity in previous work on alumina and a band indicated at ∼300 nm may be associated with Mg²⁺ or Ca²⁺_, the presence of which was confirmed by elemental mapping. Comparison of the spatial distribution of CL with the surface morphology and elemental composition of the samples indicates that the components of the emission spectrum can be qualitatively correlated with impurity content and morphological features of the samples.     

自动扶梯事故频发原因分析及对策探讨

自动扶梯事故类型可分为:坠落、碰撞、剪切、挤压、跌倒等。针对近来自动扶梯事故频发现象,本文分析其产生原因,并提出相应的解决对策。     

关于DF4B型机车电路接地原因的几点分析

本文就内燃机车发生的接地事故进行原因分析,并提出防治建议。     

突发性环境污染事故应急GIS系统框架的建立

对环境污染事故应急预警系统进行了研究，阐述了构成预警系统各子系统的设计过程与开发方法，对各子系统的主要构成和功能详细划分，探讨了在事故发生前、中、后各子系统发挥的重要作用，最后对GIS技术在突发性环境污染事故应急预警系统中的应用前景提出了一些看法。     

Telephone chip-cards as individual dosemeters

It has been observed that a certain type of telephone chip-card can be used as radiation detectors for individuals exposed to external gamma doses. The radiation dose responses of more than 200 chip-cards, produced by various companies since 1990, were investigated using infrared stimulated luminescence (IRSL). The radiation dose responses of some of the chip-cards were found to be compatible with commonly used synthetic phosphors that are used for routine occupational dose monitoring. The IRSL signal is shown to be linear with a radiation dose from 250 mGy to 5 Gy and stable at ambient temperature, which allows the use of such chip-cards for reconstruction of doses for individuals.     

Introducing a modified gradient vector method for optimization of accident prediction non-linear functions

In this paper, a new optimization method has been proposed for accident prediction non-linear models. This has been achieved by eliminating the Hessian matrix from the equation of optimal pace length in the gradient vector method. One advantage is that it is independent of the starting point in optimization processes and it provides convergence at the highest top as well. This method has been tested on an accident prediction model and its preference over the gradient vector method has been proven.     

Investigations of touchscreen glasses from mobile phones for retrospective and accident dosimetry

Touchscreen glasses of mobile phones are sensitive to ionizing radiation and have the potential of usage as an emergency dosimeter for retrospective dosimetry for the purpose of triage after a radiological accident or attack. In this study the TL glow curves and dosimetric properties of touchscreen glasses were studied in detail, such as intrinsic background dose, dose response, reproducibility, optical stability and long-term stability of the TL signal.Preliminary results are additionally presented to minimize the intrinsic background dose by mechanically removing the surface layer of the glass samples. Additionally chemical element analyses of the touchscreen glass samples were carried out to investigate the difference between glass samples which show a TL signal and samples which show neither an intrinsic zero dose signal nor a radiation induced TL signal.An irradiation trial using glass samples stored in the dark demonstrated a successful dose recovery. However, when applying a realistic, external light exposure scenario, dose underestimation was observed, even though samples were pre-bleached prior to measurement. More investigations have to be carried out in the future to solve the challenge of the low optical stability of the TL signal, if touchscreen glasses are to be used as a reliable emergency dosimeter.     

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利用通用有限元程序ANSYS对中国氦冷固态氚增殖剂实验包层模块(CH HCSB TBM)第一壁进行了稳态热分析。结果表明,第一壁铍保护板和RAFM钢的最高温度符合热工安全设计要求。对第一壁表面热流密度随时间变化的瞬态情况进行了分析,给出了随时间变化的结果。对第一壁两种典型的事故情形开展了初步分析,并对分析结果和事故影响进行了相应讨论。     

华龙一号燃料组件错装载事故计算分析王昆鹏,

本文基于华龙一号的堆芯设计参数,采用SCIENCE V2程序进行了堆芯装载方案的建模,同时计算分析了富集度相同的燃料组件、富集度不同的燃料组件两种类型共计20个燃料错装载的方案。计算结果表明,华龙一号堆芯燃料管理设计的各种错装载方案中,大多数在做启动物理试验的堆芯功率分布测量时能被发现,重新检查装料方案并更正,即可排除事故;未被发现的错装载方案中,绝大多数的F_ΔH仍满足设计限值,不影响核电厂的运行安全;仅有个别的错装载方案,未被发现且F_ΔH超过设计限值,但在正常运行工况下,满足相应的安全限制准则,且安全裕量较大。     

先进机场场面导向和控制系统:(A-SMGCS)分析与实现

放眼全球化的当今社会,航空交通密度日益增大,一些具备传统SMGCS(Surface Movement Guidance and Control System机场导向和控制系统)系统的机场运营过于繁忙,趋近饱和。本课题的研究目的在于找到一种方法,对这种困境提出缓解方案。与SMGCS相比较,A-SMGCS(Advanced-Surface Movement Guidance and Control System,先进机场场面导向和控制系统)拥有更为先进的功能,具体分为四部分:监视,路由,导向,控制。本文将对A-SMGCS的应用背景和发展状况给出较为全面的调研总结,并结合ICAO(International Civil Aero-nautics Organization,国际民间航空组织)A-SMGCS手册的论述对A-SMGCS提出详细性能需求,最后在此基础上提出A-SMGCS的系统功能架构和初步实现方法。A-SMGCS的引入可以有效地提高机场运营效率,降低事故率。