一种单模-多模-单模结构的干涉型光纤温度传感器

SMS光纤结构是一种近年来新兴的光纤器件,该结构光纤具有结构简单、易于实现、成本低廉、灵敏度高和无温度应力交叉敏感等特性.在光纤传感技术领域是一种继光纤光栅之后的具有广泛发展前景的光纤器件.从理论上分析了SMS结构和SMS级联结构的光纤传感原理,并从实验上研究了SMS结构和级联SMS结构的温度传感特性.实验表明:对于SMS结构光纤传感器,随着温度的增加,特征波长移动量逐渐增加,向长波方向漂移了4.05 nm,其传感器的温度灵敏度为15.76 pm/℃;对于级联SMS结构的光纤传感器,级联后不改变原来SMS结构的中心波长的位置,两个SMS结构仍然是独立的,不相互影响.所以说将两个SMS结构串联是可行的,可以用于温度和应力的同时测量,也可以用于分布式光纤传感器.     

Effect of electron correlations on the structure of photoprotein substrates

The electronic structure and total energy of various isomeric forms of coelenterazine and coelenteramide have been calculated by quantum chemistry methods both in the single-electron approximation and taking into account correlation effects. It has been shown that the inclusion of electron correlations makes it possible to obtain the structure of the coelenteramide close to the experimentally determined structure, as well as to choose the structure of the coelenterazine CLZ(1H) as the most probable isomeric form.     

格芯夹层结构散热性能的数值计算评估

为评估格芯夹层结构的传热性能以及代替传统的板式肋片结构应用于汽车散热系统中的可能性,文章对几种典型的格芯夹层结构（如kagome lattice,tetrahedral lattice和pyramidal lattice）和板式肋片（corrugated plate）结构实施了一系列的三维数值计算评估.通过对比相同Reynolds数下的传热系数和相同泵功率下的局部Nusselt数来评估各组结构的传热性能.结果显示,相同Reynolds数条件下,各组格芯夹层结构的传热系数较板式肋片结构均有提高,同时摩擦阻力也大幅度增大.在相同泵功率条件下,由于板式肋片结构所受形阻基本可以忽略,因此在较低泵功率范围内（< 1 500 W）,板式肋片的局部Nusselt数最大.随着泵功率的增长,当泵功率提高到3 000 W,tetrahedral的Nusselt数与板式肋片持平并进一步增大,显示出了格芯夹层结构的应用潜力.高传热性能而低摩擦阻力的格芯夹层结构完全有潜力代替传统的板式肋片结构应用于新型高效紧凑的散热系统中.      

基于区域分类、自适应滑动窗和结构检测的合成孔径雷达图像联合降斑算法

为了克服传统的基于合成孔径雷达(SAR)图像局部统计特性的降斑算法的缺点,提出了基于区域分类、自适应滑动窗和结构检测的联合降斑算法.首先,联合降斑算法对当前区域进行区域分类,并直接保留强边缘结构和点目标.接着,联合降斑算法对均匀区域和弱边缘结构区域进行滑动窗的自适应增长,从而获得合适的滤波窗口.最后,联合降斑算法对新的滤波窗口使用区域分类.如果滤波窗口属于均匀区域,则直接使用均值滤波;如果滤波窗口属于边缘结构区域,则进一步使用结构检测,并且选择窗口内的均匀子区域作为最终的滤波区域.降斑实验表明,联合降斑算 关键词： 区域分类 自适应滑动窗 结构检测 联合降斑算法     

Experimental research on the perception space of Chinese syllable

The perceptive multi-dimension structure of Chinese syllables is studied by psychological-physical experiment. The results indicate that FO and duration are interrelated to two main dimensions of the perceptive structure of Chinese syllable. And the prosodic characteristics such as the position of syllable in prosodic hierarchical structure, as well as the stress will be induced the various distribution of syllable in perception space.     

对称结构光纤光栅耦合器及其应用

光纤光栅耦合器(FGC)具有光纤光栅良好的波长选择特性和光纤耦合器的多端口特点，易于实现全光纤的光波分插复用。光纤光栅耦合器主要有4种结构：基于M Z干涉仪的分离型、基于100％耦合器的非对称型、基于0耦合器的非对称型和基于100％耦合器的对称型。着重介绍对称结构光纤光栅耦合器的结构、工作原理和研究现状。提出了测试方案，并探讨了这种器件在大规模波分复用光纤传感器阵列中的应用。     

Temperature profile of the multilayer structure irradiated by pulsed laser

Two programs are developed to calculate the temperature profile, as well as the reflectance, transmittance and absorption of a given multilayer film structure, in order to better understand the laser energy distribution between the reflectance, transmittance and absorption in each film layer. An inorganic Blu-ray recordable disc (BD-R) structure is used as a practical demonstration of the multilayer structure. The reflectance and absorption of the BD-R structure exhibit opposite trends and oscillate repeatedly with varying lower or upper dielectric layer thickness while the rest of the film thickness remains unchanged. The energy absorption in an absorbed layer depends on the thickness of the dielectric layers, its relative position in the structure and the extinction coefficient of its optical constant. The total absorption ratio of its maximum to minimum can be over 3 when changing the lower dielectric layer thickness of the studied structure. The layer thickness acts as an energy valve to control the energy flow into the multilayer structure. The thermal profile of the multilayer film structure irradiated by a pulsed laser is calculated at different positions in the film layers with time. The calculated temperatures in the recording alloy layer exhibit linear relationship with the applied power level. The effect of the laser duration time on the temperature increase in the recording layer is significant in the first few nanoseconds and becomes saturated if the heat balance is established in the structure. The calculated temperature is consistent with the experimental recording result when the structure is recorded at 4-time BD-R recording speed.     

Collective intermediate structure in the giant resonance of28Si

The theory of collective correlations is applied to²⁸Si. The main structure of photonuclear experimental data is explained nearly quantitatively. A classification of the various structure as doorway- or one particle- one hole structure, collective intermediate structure and non collective structure is proposed.     

旋翼尾流时空发展二维速度场的实验研究

旋翼作为直升机的主要升力和操纵部件, 具有复杂的流场结构, 如非定常性, 桨-涡干扰和桨尖涡等, 导致旋翼流场研究十分困难. 针对这一问题, 结合锁相技术和粒子图像测速(particle image velocimetry, PIV)技术开展了悬停状态下旋翼流场的实验研究, 并通过本征正交分解(proper orthogonal decomposition, POD)提取主要含能模态, 刻画流场时空演化. 结果显示, 旋翼尾流发展过程中向旋转轴靠近, 二维流场结构呈现倒三角结构, 即扩展到三维流动中会呈现倒锥型结构的特性; 通过POD进行含能模态分析, 旋翼尾流中对湍动能贡献最大的为桨叶涡结构, 其次是桨尖涡结构.      

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给出了中国ITER氦冷固体增殖剂(HCSB)实验包层模块(TBM)整体结构的初步设计。结构设计方案以低活性铁素体钢(RAFS)为结构材料,稳定性极好的惰性氦气作为冷却剂,陶瓷硅酸锂小球为氚增殖材料。包层结构的设计特点是,采用模块化的设计方案,从而提高了包层的可靠性和安全性。     

On the Lindemann law of melting of solids

The Lindemann law of melting has been investigated by lattice dynamics. It is found that the law is not universal so far as the Lindemann parameter is concerned, and is structure and interaction dependent. This holds separately for each class of solids having similar structure and inter-particle interaction; i.e. the parameter has one value for all solids possessing the same structure as well as interparticle interaction.     

Multistage opto-neuromorphic process system based on commercial optoelectric devices

This paper proposes a structure for opto-neuromorphic processes by using multistage connections of photo-transmitters. The basic unit consists of a light-emitting diode and a photoresistor for a non-inverting photo signal processor. By constructing a cascade structure of these basic units, multistage photo transmission of input light signal is examined in pulse signals with various periods and duty cycles as the input to the first opto-neuromorphic stage. This approach verifies that optical signals can be transmitted through our proposed structure and that by controlling the amount of the transmitted light between the basic units, the gain between stages can be controlled. It is demonstrated that this structure can be used for opto-neuromorphic processes by transmitting light signals as if transmitting signals between neurons with different weights and activation patterns. The proposed structure can be modified with an inverter circuit to build a photo-inverter and by using a combination of photo-transmitter and photo-inverters, it can serve as the basic structure to build more complicated opto-neuromorphic process systems.     

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采用多层线圈并联,每层多匝的结构设计出ITER假负载。通过ANSYS建立该线圈的结构模型,对额定电流7.75kA连续运行和68kA脉冲电流运行两种模式下进行了动力学稳定性和热稳定性分析。分析结果验证了该线圈结构的假负载的设计合理性,为其进一步的优化设计奠定了基础。     

去除铝基板的大功率LED热分析

提出一种大功率LED免铝基板封装方式,采用ANSYS有限元热分析软件对传统的铝基板封装和免铝基板封装的LED进行模拟对比分析。模拟结果表明:两种封装结构的LED,其最高温度均出现在LED芯片处;对于单颗功率1 W、3颗功率1 W和单颗功率3 W的器件,由于有效地简化了散热通道、大幅度降低了总热阻,采用免铝基板结构的最高温度分别降低了6.436,9.468,19.309 ℃。传统的铝基板封装即使选用热导率高达200 W/(m·K)的基板,其散热效果依旧略逊于免铝基板封装结构,且随着LED功率的增大,免铝基板的新型封装结构散热优势更加明显。本文的研究为解决大功率LED的散热问题和光色稳定性问题提供了一种新途径。     

Two-dimensional measurement of density,velocity, and temperature in turbulent high-speed air flows by UV rayleigh scattering

Instantaneous cross-sectional images of turbulent air flows with densities on the order of one atmosphere or less can be obtained in a straightforward manner using far ultraviolet Rayleigh scattering. These images give quantitative values for the air density and show the details of turbulent structure, shock structure, and shock wave/boundary layer interactions. Two-dimensional spatial correlations taken from multiple images give the shape and extent of average turbulent structure as well as the coupling between turbulent structure and other flow features. This technique may be extended to observe velocity fields by either double pulsing the illumination source or by using a narrow linewidth atomic or molecular filter window in front of the detector array. The latter approach also yields temperature. Used in conjunction with flow marking techniques such as RELIEF, coupling between turbulent structure and velocity fluctuations can also be determined. These diagnostic techniques can be extended to combusting flows to observe instantaneous structure, mixing, flame front location, and velocity fields.     

Metallic subwavelength structures for a broadband infrared absorption control

We present a method to control the absorption of a resonator by using a subwavelength structure consisting of thin metallic plates that behaves as a metamaterial film. We demonstrate the ability to tailor the conductivity of such a metallic subwavelength structure to achieve a resonator with the desired impedance matching for the mid-infrared range. This approach provides for broadband, as well as broad-angle, enhanced absorption. Theoretical analyses, as well as experimental results of the optical properties of a metallic NiCr structure at 8-12 microm spectral range are introduced.     

Fiber-optic microbend sensor structure

We proposed and experimentally investigated a novel microbend sensor structure. The structure is composed of single-mode leads and multimode sensing fiber. The proposed structure exhibited a level of sensitivity as much as six times higher than that of the classical microbend sensor configuration when the same sensing fiber was used. Additionally, single-mode leads reduce lead noise and allow the use of more-coherent sources. The total loss of the proposed nondeformed structure is near 2 dB when the proper splicing method is used.     

On the possibility of Pr III having a thcp structure

Crystallographic calculations have been carried out for a triple hexagonal close-packed (thcp) structure using data for Pr III, a high-pressure form shown by praseodymium metal. McMahan and Young proposed thcp as an additional high-pressure phase in the rare earth metals structural sequence. As applied to Pr III data at 14.4 GPa pressure, this structure type accounts for most but not all of the diffraction lines. Thus, we are unable to establish conclusively that Pr III has a thcp structure. However, it is shown that the thcp structure fits the Pr III data as reasonably as other structural forms proposed by other authors.     

Boron at tera-Pascal pressures

The study of boron structure is fascinating because boron has various allotropes containing boron icosahedrons under pressure. Here, we propose a new boron structure (space group $Fm\overline{3}m$) that is dynamically stable at 1.4 tera-Pascal (TPa) using density functional theory and an evolutionary algorithm. The unit cell of this structure can be viewed as a structure with a boron atom embedded in the icosahedron. This structure behaves as a metal, and cannot be stable under ambient pressure. Furthermore, we found electrons gather in lattice interstices, which is similar to that of the semiconductor Na or Ca$_{2}$N-II under high pressure. The discovery of this new structure expands our comprehension of high-pressure condensed matter and contributes to the further development of high-pressure science.     

小世界网络与无标度网络的社区结构研究

模块性(modularity)是度量网络社区结构(community structure)的主要参数.探讨了Watts和Strogatz的小世界网络(简称W-S模型)以及Barabàsi 等的B-A无标度网络(简称B-A模型)两类典型复杂网络模块性特点.结果显示，网络模块性受到网络连接稀疏的影响，W-S模型具有显著的社区结构，而B-A模型的社区结构特征不明显.因此，应用中应该分别讨论网络的小世界现象和无标度特性.社区结构不同于小世界现象和无标度特性，并可以利用模块性区别网络类型，因此网络复杂性指标应该包括 关键词： 模块性 社区结构 小世界网络 无标度网络