一种实用的火箭尾焰粒子辐射参数计算方法

为了高效计算固体火箭尾焰中粒子的红外辐射规律,基于MIE散射理论建立了辐射特性计算模型,并研究了Al2O3粒子复折射率的计算方法和尾焰中固体粒子尺寸分布律计算模型。并利用上述模型,仿真分析了典型条件下Al2O3粒子的辐射参数。结果表明在仿真条件下尾焰中固体粒子辐射特性主要取决于散射特性,并随粒径增大散射相函数方向性明显增强。最后,利用建立的模型计算了典型条件下某型固体火箭尾焰的红外辐射特性,并通过与权威文献结果对比验证了模型合理性。     

气动加热下高温陶瓷材料的红外辐射机理与特性

从分析材料内部热辐射与导热耦合传热温度场、表面反射及折射之间的内在关系出发,建立了气动加热下高温陶瓷材料的红外辐射模型.采用控制容积法结合蒙特卡罗法和谱带模型,数值模拟了红外辐射能在材料内部的传递及出射过程.引入介质影响因子,分析了材料的红外辐射机理和外部气动热流对材料红外辐射特性的影响.结果表明,高温陶瓷材料内部热辐射的光谱选择性与温度场的耦合,导致高温陶瓷材料的红外发射率随气动热流变化而变化.由于陶瓷材料在紫外和中远红外谱带范围对辐射的吸收非常强,而在近红外和可见光谱带范围对辐射吸收较弱,随气动热流密度增大,对陶瓷材料表面红外辐射产生贡献的内部热辐射区域增大,但材料的红外发射率降低.     

防离子反馈膜粒子阻透率随环境温度变化的模拟研究

覆有防离子反馈膜的微通道板是第三代微光像增强器的核心部件之一。真空高温烘烤除气过程对防离子反馈膜粒子阻透特性会产生破坏性的影响。文中利用分子动力学方法模拟计算并得到Al2O3 薄膜的膜层密度随环境温度的变化规律。利用蒙特卡洛方法模拟计算了Al2O3 薄膜的电子透过率和离子阻挡率随入射粒子能量的变化曲线。得到Al2O3 薄膜的死电压在235 V 左右,同时得出防离子反馈膜离子阻挡率在入射离子能量降低后有所增加。在入射离子能量降低为250 eV 时,C、N、O 离子被Al2O3 薄膜阻挡的比率高达96%-99%。综合以上因素分析得出,随着外部温度的升高,电子透过率线性增加,而离子阻挡率非线性的下降。合理优化并调整高温烘烤时间和量值将有助于防离子反馈膜工作性能的改善。     

固体火箭发动机地面和飞行过程中羽流红外辐射的计算研究

为研究固体火箭发动机地面和高空飞行过程中羽流红外辐射随飞行高度的变化,计算了某型固体火箭发动机在地面试车和7.5~80 km之间一系列高度工况下,发动机内、外流场和红外波段2~6μm的辐射。发动机内流和羽流流场采用非平衡化学冻结模型计算,高温Al2O3颗粒和燃气组分混合的羽流辐射场采用FVM模型计算,其中燃气组分的光谱特性用WSGG模型计算,Al2O3颗粒的光谱特性用Mie理论计算。研究了2.7~2.95μm、3.6~3.85μm和4.2~4.45μm三个波段,羽流高温核心区表面的辐射强度;以及高温核心区在轴向主平面和法平面上,0°、45°和90°三个视角的辐射亮度。研究发现:随飞行高度上升,环境压力下降,羽流体积膨胀,其中高温核心区气相温度迅速下降,Al2O3颗粒浓度也所有下降,但颗粒温度仍比较高。发动机在地面工作时,羽流的强辐射带沿其轴线呈连续状分布;但在高度小于22.5 km的低空飞行时,羽流的强辐射带除了出口区域以外,还在出口下游的后燃区出现。羽流的红外辐射亮度在纵截面上具有轴对称性。在光谱分布方面,发动机飞行高度小于40 km时,羽流辐射呈现燃气辐射的光谱差异性,但发动机在40 km高度以上飞行时,羽流辐射呈现高温颗粒辐射的光谱连续性。     

纳米TiO2粉晶的光学特性研究

用溶胶-凝胶方法(Sol-gel)制备了平均粒度为22nm的纳米TiO₂粉晶.用X射线衍射(XRD)分析了粉晶的结构变化,并用红外光谱法(IR)及紫外-可见光谱法(UV-VIS)对粒子的光学特性进行了分析.结果表明:经不同温度热处理的纳米TiO₂的光学性能随其晶型转变及粒子尺寸的变化而有着显著变化,与粗晶TiO₂相比,纳米TiO₂粒子在纳米尺度内,IR吸收边有明显红移和蓝移并存现象,而UV-VIS吸收边随粒子尺寸减小发生蓝移,表现出量子尺寸效应.     

Mie散射理论测量粒子系复折射率的透射方法

粒子的光学常数并不等同于构成粒子材料的光学常数,而通过粒子光谱复折射率数据,研究粒子及聚集粒子系的辐射特性,不仅对辐射物性的研究具有较高的理论意义,而且具有广泛的实际应用价值。粒子的复折射率不能直接通过实验测量(没有直接测量的仪器),须由实验测定其他量,然后结合相应的理论模型反求,属反问题研究。用简化的Mie散射理论及Kramers-Kronig关系式,利用傅里叶红外光谱仪对Al2O3粒子及煤灰粒子进行透射率实验测量,结合相应的理论模型,反演Al2O3粒子及煤灰粒子的复折射率。并对透射率实验误差对反演结果的影响进行了分析。     

灾害医学救援中应把握的几个要点

制备了具有不同Al2O3含量的(Ca0.7Nd0.3)(Ti0.7Al0.3)O3微波介质陶瓷,并通过XRD、SEM、能谱分析(EDS)及材料介电性能测试结果的分析研究了Al2O3对陶瓷体烧结性能、介电性能和显微结构的影响.结果发现,添加Al2O3后体系主晶相未发生改变,仍为正交钙钛矿结构.Al2O3的添加促进了晶粒的生长,有效地降低了体系的烧结温度,材料的介电常数不随Al2O3的添加发生明显变化,但其品质因数与对应频率的乘积(Q×f)值则随添加量的增大呈先上升后减小的趋势,最高可达25 153 GHz.     

紫外波段大气背景与目标特性研究

基于太阳紫外辐射在大气中散射模式理论,对紫外波段大气传输与背景变化进行了分析.分析了紫外辐射在不同波段与高度下,大气水平与垂直两个方向的传输特性.分析了不同波段的大气背景变化,以及不同季节、地理位置、地表反射率和气溶胶类型对大气背景的影响.     

355nm紫外激光抛光Al_2O_3陶瓷作用机理的实验研究

陶瓷材料的性能优越,但是表面质量差,采用短波长激光抛光技术可以有效提高陶瓷材料表面质量。针对紫外激光抛光Al2O3陶瓷过程中可能存在的熔化、汽化、微裂纹、材料的熔融飞溅和光化学作用等不同的作用形式进行了实验研究。通过对抛光后表面形貌特征进行观测,研究了紫外激光抛光Al2O3陶瓷的作用机理,并分析了高能量密度下产生的白色粉末的形貌、附着力、组成成分和主要物相,进一步确定了紫外激光抛光Al2O3陶瓷的作用机制。     

固液混合火箭发动机尾焰的红外特性研究

针对固液混合火箭发动机中Al2O3颗粒运动的影响,对喷管的内流场和外流场进行了一体化数值仿真,得到了温度、压力、组分浓度以及粒子浓度等参数的分布。利用以最新的分子光谱数据库HITRAN和HITEMP为基础编写的逐线积分法计算了气体光谱吸收系数,采用米氏散射模型计算了固体粒子的辐射特性参数。利用基于有限体积法离散辐射传输方程的模型计算出了尾焰的红外辐射亮度。通过进一步求解,得到了特定波段的光谱辐射强度。在8—14岬波段,利用红外热像仪进行了试验,并将试验结果与数值计算结果进行了比较。结果表明,该计算模型和方法能较好地模拟固液混合火箭发动机尾焰的红外辐射特性。     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Teleportation of an arbitrary unknown N-qubit entangled state under the controlling of M controllers

A new quantum protocol to teleport an arbitrary unknown N-qubit entangled state from a sender to a fixed receiver under M controllers(M < N) is proposed. The quantum resources required are M non-maximally entangled Greenberger-Home-Zeilinger (GHZ) state and N-M non-maximally entangled Einstein-Podolsky-Rosen (EPR) pairs. The sender performs N generalized Bell-state measurements on the 2N particles. Controllers take M single-particle measurement along x-axis, and the receiver needs to introduce one auxiliary two-level particle to extract quantum information probabilistically with the fidelity unit if controllers cooperate with it.     

Diode-end-pumped Nd:YVO4/LBO lasers with 4.2W continuous-wave output at 457 nm

A continuous-wave (CW) 457 nm blue laser operating at the power of 4.2 W is demonstrated by using a fiber coupled laser diode module pumped Nd: YVO4 and using LBO as the intra-cavity SHG crystal With the optimization of laser cavity and crystal parameters, the laser operates at a very high efficiency. When the pumping power is about 31 W, the output at 457nm reaches 4.2 W, and the optical to optical conversion efficiency is about 13.5% accordingly. The stability of the out putpower is better than 1.2% for 8 h continuously working.     

Call for Papers

正Wireless Body-area Networks The last decade has witnessed the convergence of three giant worlds:electronics,computer science and telecommunications.The next decade should follow this convergence in most of our activities with the generalization of sensor networks.In particular with the progress in medicine,people live longer and the aging of population will push the development of wireless personal networks     

Call for Papers—Feature Topic,Vol.12,No.7,2015

正Information Centric Networking Information-Centric Networking(ICN) is an emerging direction in Future Internet architecture research,gaining significant tractions among academia and industry.Aiming to replace the conventional host-to-host communication model by a data-centric model,ICN treats data content as the first     

JOURNAL OF ELECTRONICS(CHINA)

正~~     

NOTICE OF CHANGING JOURNAL OF ELECTRONICS （CHINA） TO MICROSYSTEMS ＆ NANOENGINEERING

正Journal of Electronics(China)(JE)was founded in 1984,sponsored by the Institute of Electronics,Chinese Academy of Sciences.JE is one of the first English academic journals in China in the field of Electronics and Information technology.The journal was published quarterly since it was launched in 1984 to 2003,then it is published bimonthly till now.During