低轨卫星星座网的切换研究

提出了一种适用于装备有星际链路的低轨卫星星座网的切换策略——最小跳数切换策略。该策略以端到端连接的跳数为基础,充分利用了低轨星座网的特点,将切换过程与路由有机地结合为一体,有效解决了不同卫星之间的切换问题。仿真结果表明,同已有的切换策略相比,该策略能够提供一定程度的QoS保障,获得较好的系统性能,如较低的传播延时和较小的切换频率,具有很好的实用价值。     

一种基于历史信息的干扰信号预测算法

基于历史数据的预测方法使用较为广泛,但对数据的类型与特征依赖很大.低轨卫星通信系统获得的频谱感知数据中有时间信息与位置信息.结合这一特性,文中提出了一种基于位置相关和时间相关的干扰预测方法,并采用星上实测数据进行验证,结果表明,该算法具有较好的预测性能.     

A comparative study of two adaptive algorithms for suppression of a narrow-band interference

A comparative study of two adaptive algorithms which are available for suppression of a narrow-band interference is discussed. Two Notch Filters (NF) are presented in this paper: (1) Conventional Least Mean Square Filter (LMS-NF) and (2) Function Elimination Filter (FEF-NF). These algorithms present two different forms of linear prediction procedures, both of which are based on the LMS criterion. The first approach (LMS-NF) concerns the well-understood linear prediction. According to the second approach (FEF-NF), part of the filter coefficients are fixed and do not require any adjustment.The major part of the paper is devoted to the quantitative analysis of the considered algorithms. This analysis is carried out by studying the change in the Signal-to-Interference Ratio and the Bit-to-Bit Power Ratio due to a change in an additive noise level and in a power of a sinusoidal interference. The nature of the considered filters and their performances are demonstrated through digital computer simulation.     

红外源强度对激光干扰效应的影响

分析了红外目标源辐射强度随距离和时间的变化。在不同红外源强度的 条件下，进行了红外源强度对红外系统输出信号的响应定标。同时，在激光辐照功率67W和辐照时间460ms条件下，用1.06μm连续ND：AYG激光对不同红外源强度下红外系统输出信号的干扰效果进行了对比实验。结果表明：激光对红外系统的干扰效果与红外目标源的强度成正比。当红外源强度在红外系统工作的线性范围时，激光对红外系统的干扰效果最明显。     

Simulation based study of thermal effects on periodic nanostructures fabricated by laser interference

Laser interference based direct writing is a potential solution for wide range of fabrication of nanostructure. This paper deals with two dimensional heat conduction analysis and the simulation of the same on silicon and germanium surfaces. Simulation of direct writing of patterns with 193 nm, 27 nsec, single pulse laser source with power varied from 800 mJ/cm² to 1100 mJ/cm² are presented. The rise in the temperature on the surfaces as well as beneath the surface is analyzed on the basis of the results. We also report about the dependency of the thermal diffusion length on the homogeneity of the formed structures.     

移动卫星系统与LTE网络间干扰共存性能的研究

The interference coexistence performance between the systems of a Long Term Evolution (LTE) network and Mobile Satellite Service (MSS) system, both of which work around the frequency of approximately 2 GHz according to the bandwidth allocation in China, is proposed in this article. The related background of an MSS system and the common terminologies are introduced. Further, the coexistence scenarios of different coverage situations shared by the two systems are discussed. The interference impact of an MSS transmission on an LTE system is evaluated using a specific Monte Carlo method. Finally, simulation results show that although no crucial issues for the coexistence of an LTE downlink and the MSS are observed, the LTE uplink suffers a considerable amount of interference from the MSS transmission. Given the insufficient isolation between LTE and MSS existing networks, and the rapid advance in the field of LTE, problems may emerge in the near future. Further, this article can be of sig-nificance in providing reference for frequency spectrum planning in the existing LTE net-works.     

基于SMI—LMS的自适应旁瓣干扰抑制算法研究

提出基于SMI—LMS的自适应旁瓣干扰抑制算法,即利用采样矩阵求逆（SMI）算法计算初始权值,并以此作为LMS算法的初值。通过比较分析LS-LMS和SMI—LMS的方向图增益和运算量,并运用对角加载技术对SMI-LMS算法作出改进,验证了SMI-LMS算法的优势。仿真实验表明,SMI-LMS算法具有快的收敛速度和低的算法复杂度,在低快拍下有着好的性能。     

Numerical study on the properties of an active sun tracker for solar streetlight

In this work, a new active sun tracker for solar streetlight combined with photoelectric tracking mode mainly and time-based tracking mode auxiliary was proposed. The sun tracker was designed through three aspects: mechanical structure, electrical system and control procedure. Then, a proper model named Available Energy Absorption Model was built to study the energy efficiency. The numerical average value of energy efficiency in a year is 36% which shows the superiority of the tracking mode on the available energy absorption. Lastly, the mechanical properties analysis of the tracker was implemented on two aspects which include motion simulation and wind resistance. The numerical results prove the feasibility of the double-slider mechanism and the reliability of the tracker’s strength.     

激光淬火过程中光的干涉和衍射结构的热作用研究

为提高激光热处理的质量,国内外利用光束分割再重新复合的方法,研究成功不少光学系统.由于激光是高相干光,光的干涉及衍射结构使复合光斑的功率密度分布复杂化,严格研究热处理过程中光与材料的相互热作用变得非常困难.在文献[1]中,我们从一个简单的光学系统研究出发,从理论上证明,当光的干涉和衍射条纹的间距相较于作用光斑的尺寸而言甚小时,可以忽略这些条纹结构对金属材料热处理的影响,并可以利用几何光学所预言的激光功率密度分布来进行有关的热学计算,为使这个结论更具有一般性,本文导出便于使用的判断光的干涉及衍射结构的热影响可否忽略的表达式,同时给出实验结论.     

A comparative study on the performance of MIMO MRC systems with and without cochannel interference

This paper presents exact closed-form expressions for the performance of multiple-input/multiple-output systems employing maximal ratio combining in the absence and presence of cochannel interference. The results are applicable to systems operating over Rayleigh fading channels, and in which the minimum number of antenna elements at the transmitter and receiver is two. The mathematical formalism is illustrated by some numerical examples which study the effects of various parameters on the system performance.     

非、单晶硅太阳能电池组件比功率发电量对比研究

通过比较单晶硅与非晶硅比功率发电量,分析两者在太阳能发电功效上的具体差异.     

正交偏振光分开探测的He-Ne激光自混合干涉的实验研究

实验研究了He-Ne激光的一般自混合干涉和垂直偏振光分开探测的自混合干涉。研究表明,由于相邻纵模的模竞争效应,在垂直偏振光分开探测的He-Ne激光自混合干涉输出光强中,始终有一种光强占优势。这种优势是随机的,并且与自混合干涉前的光的偏振态无关。     

红宝石激光单脉冲全息照像出现干涉条纹的讨论

本文指出调Q红宝石激光器的单纵模选择是非常困难的。若激光器的两个相较透的纵模同时振荡,纵然我们用单脉冲一次照全息像,当再调时也会有干涉条纹出现。本文指出干涉条纹的出现实际上是相干长度呈周期性的表现。只要采取相应措施保证单纵模运转,就可以消除这种现象。本文还指出了提高相干长度的办法。     

多径干扰对再入遥测系统性能的影响分析

多径干扰在频域表现为在PCM/FM的频谱中产生凹陷。我们通过用一直射路径和一延时小于一个比特间隔的镜面反射路径来模拟再入遥测多径信道,并结合一延时解调器,得到了系统的性能方程式,它是多径信道参数r、θ和τ的函数。然后就有和无预检波滤波器分别分析了多径干扰对系统性能的影响。通过分析得出,系统的比特错误概率都强烈依赖于凹口的位置,而在无预检波滤波器时,系统的平均比特错误概率与凹口的宽度(时延τ)无关,主要由凹口的深度(反射系数r)确定,此时由于多径干扰引起系统性能损失的上界为1/(1-r)2,它高出实际系统性能的损失值不到1dB。在有预检波滤波器的情况下,系统的平均比特错误概率与凹口的宽度、凹口的深度和滤波器的带宽都有关。当τ/Tb=0.15时系统性能最差,而滤波器的带宽B越窄,码间干扰越严重,在τ/Tb=0.15且BTb=1时,得到了系统性能损失的上界为:1/(1-r)2r,它超过系统性能的实际损失同样小于1dB。     

雷达之间的干扰及概率计算

两部雷达在天线对准时会产生相互影响,严重时可能出现烧毁接收机前端的现象。本文分析了雷达之间的电磁兼容问题,给出了干扰信号强度的计算方法。研究了各种雷达天线对准概率的计算方法,并给出了计算实例。     

垂直偏振态He-Ne激光自混合干涉的实验研究

从实验上研究了频率分裂激光器中偏振态相互垂直的o光和e光的自混合干涉现象,因为o光和e光之间的模竞争效应,所以在o光和e光的反馈曲线中,最大值和最小值相互对应,在一个周期中,最大值出现的次数是一般反馈曲线的2倍,幅值的变化也是一般反馈曲线的2倍。     

Experimental and simulation study for impact of different halides on the performance of planar perovskite solar cells

MeA-PbX₃ and MeA-PbI₂X (where MeA=CH₃NH₃; X=I, Br, Cl) systems have been synthesized using grinding processing. Plainly, the crystal structures of the perovskite materials were altered with the variation of the halide ions. Meanwhile, the band gap energy was enhanced from 1.5 eV for MeA-PbI₃ to 2.1 and 2.8 eV for MeA-PbBr₃ and MeA-PbCl₃ as a result of substitution by halide Br and Cl, respectively. The intensity peaks of different perovskite structures were confirmed by photoluminescence (PL). Furthermore, the following energy parameters, heat of formation, high occupied molecular orbital (HOMO) and low unoccupied molecular orbital (LUMO) were evaluated using hyperchem system software. Herein, we performed a device modeling and theoretical study on planar perovskite solar cells without a hole transporting material (HTM) using a solar cell simulation program (wxAMPS) as an update of the popular solar cell simulation tool (AMPS; Analysis of Microelectronic and Photonic Structures). Simulation and experimental design of MeA-PbX₃ and MeA-PbI₂X (where MeA=CH₃NH₃; X=I, Br, Cl) systems were investigated. The cells without HTM have been suggested to enhance the low cost and simple assembly of organic-inorganic lead halide perovskite based solar cells. MeA-PbBr₃ with HTM-free solar cells was achieved a high PCE of 13.96% in simulation program compared to 3.88% as experimental one.     

Efficient blue and bluish-green iridium phosphors: Fine-tuning emissions of FIrpic by halogen substitution on pyridine-containing ligands

Three new iridium compounds, 4-F-FIrpic, 4-Cl-FIrpic and 4-Br-FIrpic, were designed and synthesized by introducing the F, Cl and Br atoms to the 4-position of pyridine ring in the frame of sky-blue emitter, FIrpic. Adding F atom stabilizes the HOMO level of FIrpic but keeps the LUMO level of FIrpic almost unchanged, which consequently broadens the HOMO–LUMO gap of FIrpic and finely tunes the emission to 465 nm of 4-F-FIrpic from 470 nm of FIrpic. In contrast, introducing of Cl and Br atoms simultaneously lowers the HOMO and LUMO levels of FIrpic, which brings about the squeeze of HOMO–LUMO gap in FIrpic and makes the emissions of 4-Cl-FIrpic and 4-Br-FIrpic red-shift to 475 and 479 nm, respectively. The phosphorescent organic light-emitting devices using the three iridium compounds as dopants were fabricated with the following configuration: ITO/MoO₃/TAPC/TCTA:dopants/Tm/LiF/Al. The device based on 4-F-FIrpic showed a blue emission with the Commission Internationale de L’Eclairage coordinate of (0.15, 0.28), and revealed rather high efficiencies, with maximum current efficiency of 29 cd A⁻¹, power efficiency of 29 lm W⁻¹ and external quantum efficiency of 14.6%.     

COMPASS和Galileo系统间信号干扰研究

随着各国和地区的卫星导航系统建设,我国北斗COMPASS和欧盟Galileo系统间信号干扰已成为广泛关注的焦点。首先建立有效评价卫星导航系统间信号干扰的方法,其次分析COMPASS和Galileo系统的星座构型和信号体制参数,最后对两大系统间的民用信号间干扰进行仿真分析,结果表明COMPASS信号的引入对Galileo造成干扰,但其造成的干扰比Galileo对COMPASS的干扰小。所建立的评价方法和结果可为导航系统的信号体制设计和接收机应用提供理论参考。     

2.6GHz频段5G上行干扰分析与识别研究

本文针对2.6 GHz频段5G干扰小区分析与干扰类型识别问题,梳理总结了5G常见干扰类型,研究提出了一种基于干扰小区时频域特征的5G干扰分析和类型识别方法,给出了各种5G干扰类型的排查流程和方法建议,为5G干扰分析排查提供理论指导,支撑5G干扰优化工作.