Enhanced photoluminescence of Nd2O3 nanoparticles modified with silane-coupling agent: Fluorescent resonance energy transfer analysis

A liquid laser medium with a lifetime of 492 mu s and a fluorescent quantum efficiency of 52.5% has been presented by stably dispersing dimethyl dichorosilane-modified Nd2O3 nanoparticles in dimethylsulfoxide. Its optical properties and mechanism were investigated and explained by fluorescence resonance energy transfer theory. The calculation result shows that the quenching of Nd-III F-4(3/2)-> I-4(11/2) transition via O-H vibrational excitation can be eventually neglected. The main reason is that the silane-coupling agent molecules remove the -OH groups on Nd2O3 nanoparticles and form a protective out layer. (c) 2007 American Institute of Physics.

Strain analysis of InP/InGaAsP wafer bonded on Si by X-ray double crystalline diffraction

Wafer bonding between p-Si and an n-InP-based InGaAsP multiple quantum well (MQW) wafer was achieved by a direct wafer bonding method. In order to investigate the strain at different annealing temperatures, four pre-bonded pairs were selected, and pair one was annealed at 150 degrees C, pair two at 250 degrees C, pair three at 350 degrees C, and pair four at 450 degrees C, respectively. The macroscopical strains on the bonded epitaxial layer include two parts, namely the internal strain and the strain caused by the mismatching of the crystalline orientation between InP (100) and Si (100). These strains were measured by the X-ray double crystalline diffraction, and theoretical calculations of the longitudinal and perpendicular thermal strains at different annealing temperatures were calculated using the bi-metal thermostats model, both the internal strain and the thermal strain increase with the annealing temperature. Normal thermal stress and the elastic biaxial thermal strain energy were also calculated using this model. (c) 2006 Elsevier B.V. All rights reserved.

Experimental study on energy dissipation in a 1 kW arcjet thruster

As a simple and reliable propulsion system, arcjet thrusters have been used in multiple satellite missions. In order to improve the efficiency of arcjet thrusters, energy dissipation study was carried out in a 1 kW arcjet thruster with pure N2, H2-N2 and H2 as the propellant. Using a 698 nm interference filter, thermal radiation was isolated from arc and plume emissions and the internal nozzle temperature was obtained by converting the thermal radiation signals. Results show that the addition of hydrogen leads to higher nozzle temperature, which is the determining factor for the mode of arc root attachment. At lower nozzle temperatures, constricted type attachment with unstable motions of the arc root was observed, while a fully diffused and stable arc root was observed at elevated nozzle temperatures. Output energy distribution analysis shows that losses from frozen flow and exhaust thermal losses are the main parts in limiting the efficiency of arcjet thrusters.

Experimental study on energy dissipation in a 1 kW arcjet thruster

As a simple and reliable propulsion system, arcjet thrusters have been used in multiple satellite missions. In order to improve the efficiency of arcjet thrusters, energy dissipation study was carried out in a 1 kW arcjet thruster with pure N2, H2-N2 and H2 as the propellant. Using a 698 nm interference filter, thermal radiation was isolated from arc and plume emissions and the internal nozzle temperature was obtained by converting the thermal radiation signals. Results show that the addition of hydrogen leads to higher nozzle temperature, which is the determining factor for the mode of arc root attachment. At lower nozzle temperatures, constricted type attachment with unstable motions of the arc root was observed, while a fully diffused and stable arc root was observed at elevated nozzle temperatures. Output energy distribution analysis shows that losses from frozen flow and exhaust thermal losses are the main parts in limiting the efficiency of arcjet thrusters.

一种低活化铁素体/ 马氏体钢的高能重离子辐照效应研究

Low-activation Ferritic/Martensitic steels are a kind of important structural materials candidate to the application in advanced nuclear energy systems.Possible degradation of properties and even failure in the condition of high-temperature and high helium production due to energetic neutron irradiation in a fusion reactor is a major concern with the application of this kind of materials.In the present work microstructural evolution in a 9Cr Ferritic/Martensitic steel(T92B) irradiated with 122 MeV 20Ne ions...中文摘要：低活化的铁素体/马氏体钢是先进核能装置(如聚变堆)的重要候选结构材料。在聚变堆实际工作环境下,由于高温和高氦产生率引起的材料失效是这类材料面临的一个重要问题。本项研究以兰州重离子加速器(HIRFL)提供的中能惰性气体离子束(20Ne,122 MeV)作为模拟辐照条件,借助透射电子显微镜,研究了一种低活化的9Cr铁素体/马氏体钢(T92B)组织结构的变化和辐照肿胀。实验结果表明,高温下当材料中晶格原子的撞出损伤和惰性气体原子沉积浓度超过一定限值时,材料内部形成高浓度的空洞,并且空洞肿胀率显著依赖于辐照温度和剂量;在马氏体板条界面及其它晶界处空洞趋于优先形成,并且在晶界交汇处呈加速生长。基于氦泡的形核生长与空洞肿胀的经典模型探讨了在不同辐照条件(He离子、Ne离子、Fe/He离子双束、快中子、Ni离子)下铁素体/马氏体钢中肿胀率数据的关联。

A systems view of integrated coastal management

Natural hazards and human activities in the coastal zone are threatening the integrity of the coastal resource system. Conflicts of interest between short term economic benefits and long term ecologic assets should be identified and solved by means of a balanced CZM approach. Systems analysis, supported by mathematical modelling tools are the appropriate instruments to assist the coastal zone manager. The paper presents a general system description of the coastal zone, and focuses on the modelling of the natural subsystem components of this system as a first step towards a model for Integrated Coastal Management (ICM).

转子系统油膜振荡的小波包分解与频带能量比例特征分析

在介绍小波包分解原理的基础上 ,对试验测得的单盘单跨转子系统的油膜振荡非平稳信号用小波包分解方法进行了研究。采用db44小波基函数进行 4层小波包分解。给出了各频带内分解信号的特点及频带能量比例 ,其中第 3频带是该转子系统在 960 0r/min时产生油膜振荡的特征频带。得到的试验数据及其分析结果对转子系统油膜振荡研究和旋转机械状态监测等具有重要意义。

列阵透镜对能量测量影响的分析

结合列阵透镜的透过率分析了其后的光场分布。列阵透镜由多个列阵元拼接而成，用以改善主透镜焦点附近能量分布的均匀性。列阵透镜在提高辐照均匀性的同时，给能量测量带来了不利的影响。这是由于经过列阵元的相邻子光束会产生干涉，干涉条纹处的激光能量密度和功率密度相应都大为增加，其数值在干涉区域中心处能上升到原来的4倍。更高的能量密度和功率密度对能量计提出了更苛刻的要求。在没有采取适当措施的时候使用，就会损坏能量计。

808 nm 抽运的Ho3+，Tm3+及Er3+掺杂的氟磷酸盐 玻璃的2.0 μm 光谱性质研究

2.0 μm spectroscopic properties of Er³⁺/Tm³⁺/Ho³⁺ triply-doped fluorophosphate glasses pumped by 808 nm and the energy transfer mechanisms between the three rare earth ions were investigated. J-O theory was used to calculate the parameters of Ho³⁺ in fluorophosphate glasses. Absorption and emission cross-sections and the gain coefficients were calculated. The obtained lifetime r and spontaneous transition probability Ar of Ho³⁺:⁵I7 level were 10.64 ms and 93.95 s^-1 respectively. The calculated maximum emission cross-section of 2.0 μm was 9.26×10^-21 cm². The energy transfer analysis indicated that the cross-relaxation of Tm³⁺ was important and the resonent energy transfer in Er³⁺&rarrHo³⁺, Tm³⁺&rarrHo³⁺, Er³⁺&rarrTm³⁺&rarrHo³⁺ process was the main channel. The study revealed that the Er³⁺/Tm³⁺/Ho³⁺ triply-doped fluorophosphate glass would be a potential material for 2.0 μm emission because of the efficient sensitization of Er³⁺ and Tm³⁺ to Ho³⁺.

微缺陷对薄膜滤光片环境稳定性的影响

用热蒸发方法沉积了薄膜滤光片．并将样品分别在去离子水中浸泡10天和30天．通过分光光度计、光学暗场显微镜、及扫描电子显微镜等多种测试手段，对诱导透射滤光片在潮湿环境下的稳定性进行了研究．实验发现，在潮湿环境下滤光片产生的膜层分离都是从薄膜中微缺陷点处开始发生和发展的，微缺陷是影响滤光片环境稳定性的重要原因之一，其中杂质和针孔是滤光片中两种最常见的微缺陷．EDS能谱分析进一步表明，薄膜中杂质缺陷成分即为Al2O3膜料本身，所以不能推测，薄膜沉积中的喷溅可能是微缺陷产生的根本原因，抑制喷溅可以有效提高薄膜滤光

Computer-aided design of PV/wind hybrid system

A complete set of match calculation methods for optimum sizing of PV/wind hybrid system is presented. In this method, the more accurate and practical mathematic models for characterizing PV module, wind generator and battery are adopted; combining with hourly measured meteorologic data and load data, the performance of a PV/wind hybrid system is determined on a hourly basis; by fixing the capacity of wind generators, the whole year's LPSP (loss of power supply probability) values of PV/wind hybrid systems with different capacity of PV array and battery bank are calculated, then the trade-off curve between battery bank and PV array capacity is drawn for the given LPSP value; the optimum configuration which can meet the energy demand with the minimum cost can be found by drawing a tangent to the trade-off curve with the slope representing the relationship between cost of PV module and that of the battery. According to this match calculation method, a set of match calculation programs for optimum sizing of PV/wind hybrid systems have been developed. Applying these match calculation programs to an assumed PV/wind hybrid system to be installed at Waglan island of Hong Kong, the optimum configuration and its hourly, daily, monthly and yearly performances are given. (C) 2003 Elsevier Science Ltd. All rights reserved.