Al掺杂对Mg_2Si介电性质影响的第一性原理研究

采用基于密度泛函理论的第一性原理平面波超软赝势方法,计算了本征Mg_2Si和Al掺杂Mg_2Si的形成能、电子结构和介电函数.结果表明,Al掺杂Mg_2Si后,Al以替位杂质(Al替Mg位,即AlMg)或填隙杂质(Al位于晶胞间隙位,即Ali)的形式进入Mg_2Si晶格.费米能级进入导带,体系呈n型导电.掺杂后体系的介电函数的实部和虚部在低频时比未掺杂时均增大,主要是由于晶格中的施主杂质Al离子束缚着附近的过剩电子,在外加交变电场的作用下,束缚在Al离子周围的电子要克服一定的势垒不断地往复运动造成松弛极化和损耗.另外,掺杂体系相对于未掺杂体系,介电函数的虚部在0.5 eV附近出现了一个额外的介电峰,该峰主要是由电子从价带跃迁到Al杂质能级引起的.计算结果为Mg_2Si基光电子器件的设计和应用提供了理论依据.     

航天器热试验查询统计系统的设计与实现

针对航天器真空热试验数据量大、数据利用率不高的特点,提出了一种基于数据库的试验数据查询统计方法方法,以改善现有的以文件系统为主的数据存储模式;通过对试验数据格式的分析和现有工作流程的优化,将试验数据查询系统分为系统管理、试验管理、策略管理和统计分析等四个大的功能模块,利用过滤算法自动生成试验工况点信息,并通过试验工况点自动生成单次试验的统计报告,进而实现对所有试验数据的综合查询统计功能;目前系统已应用于航天器热试验任务中,经过测试,系统功能和性能指标满足试验需求,解决了实际问题。     

低分子量含氟聚合物的制备、官能化及特性

低分子量含氟聚合物是重要的新型功能材料,在国防工业中占有特殊地位。同时,作为高科技战略物资,近年来逐渐成为研究热点。本文对低分子量含氟聚合物的制备方法、官能化及特性进行了综述,重点介绍了低分子量含氟聚合物的制备和官能化方法的研究进展,并总结和详细介绍了低分子量含氟聚合物的特性,最后对该领域的前景和发展方向进行了展望。     

PMT overshoot study for the JUNO prototype detector

The quality of PMT signals is crucial for large-size and high-precision neutrino experiments, but most of these experiments are affected by the overshoot of PMT signals from the positive HV-single cable scheme. Overshoot affects the trigger, dead time and charge measurement from a detector. For the JUNO prototype detector, we have performed a detailed study and calculation on PMT signal overshoot to control the ratio of overshoot to signal amplitude to ~1%, with no effect on other PMT parameters.     

A Mixed Analytical/Numerical Method for Velocity and Heat Transfer of Laminar Power-Law Fluids

This paper presents a relatively simple numerical method to investigate the flow and heat transfer of laminar power-law fluids over a semi-infinite plate in the presence of viscous dissipation and anisotropy radiation. On one hand, unlike most classical works, the effects of power-law viscosity on velocity and temperature fields are taken into account when both the dynamic viscosity and the thermal diffusivity vary as a power-law function. On the other hand, boundary layer equations are derived by Taylor expansion, and a mixed analytical/numerical method (a pseudo-similarity method) is proposed to effectively solve the boundary layer equations. This method has been justified by comparing its results with those of the original governing equations obtained by a finite element method. These results agree very well especially when the Reynolds number is large. We also observe that the robustness and accuracy of the algorithm are better when thermal boundary layer is thinner than velocity boundary layer.     

Scalar Resonance at 750 GeV as Composite of Heavy Vector-Like Fermions

We study a model of scalars which includes both the SM Higgs and a scalar singlet as composites of heavy vector-like fermions. The vector-like fermions are bounded by the super-strong four-fermion interactions. The scalar singlet decays to SM vector bosons through loop of heavy vector-like fermions. We show that the surprisingly large production cross section of di-photon events at 750 GeV resonance and the odd decay properties can all be explained. This model serves as a good model for both SM Higgs and a scalar resonance at 750 GeV.     

Laser direct imaging of transparent indium tin oxide electrodes using high speed stitching techniques

To accomplish an electrode patterning in large area, we present a high speed stitching technique used in an ultraviolet laser processing system and investigate the interaction between laser beams and indium tin oxide (ITO) thin films deposited on glass substrates. After optimizing the process parameters of the laser direct imaging (LDI) for the large-area electrode patterning, the ablated lines looked like regularly fish-scale marks of about a 40 μm diameter and a 120 nm depth around the processing path. The parameters includes the laser power of 1W, the scanning speed of galvanometers of 800 mm/s, and the laser pulse repetition frequency of 50 kHz. Moreover, the resistance value of the ablated ITO thin film is larger than 200MΩ that is electrically insulated from the other regions of electrode structure. LDI technology with UV laser beam has great potential applications in patterning on wafer or sapphire substrates and patterning a conductive layer deposited on the touch panels for semiconductor and optoelectric industries, respectively.     

Attractive target wave patterns in complex networks consisting of excitable nodes

This review describes the investigations of oscillatory complex networks consisting of excitable nodes,focusing on the target wave patterns or say the target wave attractors.A method of dominant phase advanced driving(DPAD) is introduced to reveal the dynamic structures in the networks supporting oscillations,such as the oscillation sources and the main excitation propagation paths from the sources to the whole networks.The target center nodes and their drivers are regarded as the key nodes which can completely determine the corresponding target wave patterns.Therefore,the center(say node A) and its driver(say node B) of a target wave can be used as a label,(A,B),of the given target pattern.The label can give a clue to conveniently retrieve,suppress,and control the target waves.Statistical investigations,both theoretically from the label analysis and numerically from direct simulations of network dynamics,show that there exist huge numbers of target wave attractors in excitable complex networks if the system size is large,and all these attractors can be labeled and easily controlled based on the information given by the labels.The possible applications of the physical ideas and the mathematical methods about multiplicity and labelability of attractors to memory problems of neural networks are briefly discussed.     

Enhancing the performance of poly(3-hexylthiophene)/ZnO nanorod arrays based hybrid solar cells through incorporation of a third component

Sparse ZnO nanorod arrays(NRAs)are fabricated on transparent conducting oxide coated glass substrates by using a modified liquid phase epitaxial growth method.By adjusting the polymer concentrations and the spin-coating parameters,full infiltration of poly(3-hexylthiophene)(P3HT)into the as-prepared ZnO NRAs is achieved at 130°C in vacuum.A third component is incorporated into the P3HT/ZnO NRAs ordered bulk heterojunctions(BHJs)either through ZnO surface modification with N719dye or CdS shell layer or by inclusion of a fullerene derivative into the P3HT matrix.Experimental results indicate that performances of the hybrid solar cells are improved greatly with the incorporation of a third component.However,the working principles of these third components differ from one another,according to morphology,structure,optical property,charge transfer and interfacial properties of the composite structures.An ideal device architecture for hybrid solar cells based on P3HT/ZnO NRAs ordered BHJs is proposed,which can be used as a guidance to further increase the power conversion efficiency of such solar cells.     

Giant optical activity and circular dichroism in the terahertz region based on bi-layer Y-shaped chiral metamaterial

We present a bi-layer Y-shaped chiral metamaterial (CMM) that can realize a giant optical activity and circular dichroism (CD) effect to the incident linear polarization wave in the terahertz (THz) region. Numerical simulation results exhibit that the pronounced CD effect with a great difference between the transmission coefficients for the circularly polarized waves can be obtained at 5.06 THz, meanwhile the 90°-polarization rotation can be observed at 5.2 THz when a y-polarized wave is incident to this CMM propagating along the −z-axis. The mechanism of the optical activity and giant CD effect is illustrated by simulated surface current distributions. Further, the influences of the structural parameters of the proposed CMM to the optical activity and CD effect have been investigated numerically.