Efficient and Stable Inverted Perovskite Solar Modules Enabled by Solid-Liquid Two-Step Film Formation

A considerable efficiency gap exists between large-area perovskite solar modules and small-area perovskite solar cells.The control of forming uniform and large-area film and perovskite crystallization is still the main obstacle restricting the efficiency of PSMs.In this work,we adopted a solid-liquid two-step film formation technique,which involved the evaporation of a lead iodide film and blade coating of an organic ammonium halide solution to prepare perovskite films.This method possesses the advantages of integrating vapor deposition and solution methods,which could apply to substrates with different roughness and avoid using toxic solvents to achieve a more uniform,large-area perovskite film.Furthermore,modification of the NiO_(x)/perovskite buried interface and introduction of Urea additives were utilized to reduce interface recombination and regulate perovskite crystallization.As a result,a large-area perovskite film possessing larger grains,fewer pinholes,and reduced defects could be achieved.The inverted PSM with an active area of 61.56 cm^(2)(10×10 cm^(2)substrate)achieved a champion power conversion efficiency of 20.56%and significantly improved stability.This method suggests an innovative approach to resolving the uniformity issue associated with large-area film fabrication.

Recognition Analysis and Simulation Implementation Based on High-Order Cumulants of Wireless Digital Modulation Mode

This paper mainly studies the data characteristics of high order cumulants using digitally modulated signals, and constructs the identification feature parameters that can distinguish the signal modulation type by the high-order cumulants data of the digital modulation signal. Set the identification signal modulation type determination threshold based on the value of the identification feature parameter. The identification feature parameter value of the signal modulation type is compared with the set determination threshold, to realize the recognition of digital modulation signal. This identification method is implemented based on MATLAB design, with a 2ASK (2-ary Amplitude Shift Keying) signal, 4ASK (4-ary Amplitude Shift Keying) signal, 2PSK (2-ary Phase Shift Keying) signal, 4PSK (4-ary Phase Shift Keying) signal, 2FSK (2-ary Frequency Shift Keying) signal, 4FSK (4-ary Frequency Shift Keying) signal. The second, fourth and sixth order cumulants of the six signals were analyzed. Calculate the selected identification feature parameter value and the determination threshold to identify the six signals. The six signals have made MATLAB identification simulation. Simulation results show that this method is feasible and has high recognition rate. Simulation results verify that such recognition methods maintain a high recognition rate under conditions with low signal-to-noise ratio. This identification method can be extended to more MASK (M-ary Amplitude Shift Keying), MPSK (M-ary Phase Shift Keying), MFSK (M-ary Frequency Shift Keying), MQAM (M-ary Quadrature Amplitude Modulation) signal identification.

Cross-phase modulation instability in optical fibres with exponential saturable nonlinearity and high-order dispersion

Utilizing the linear-stability analysis, this paper analytically investigates and calculates the condition and gain spectra of cross-phase modulation instability in optical fibres in the ease of exponential saturable nonlinearity and high-order dispersion. The results show that, the modulation instability characteristics here are similar to those of conventional saturable nonlinearity and Kerr nonlinearity. That is to say, when the fourth-order dispersion has the same sign as that of the second-order one, a new gain spectral region called the second one which is far away from the zero point may appear. The existence of the exponential saturable nonlinearity will make the spectral width as well as the peak gain of every spectral region increase with the input powers before decrease. Namely, for every spectral regime, this may lead to a unique value of peak gain and spectral width for two different input powers. In comparison with the case of conventional saturable nonlinearity, however, when the other parameters are the same, the variations of the spectral width and the peak gain with the input powers will be faster in case of exponential saturable nonlinearity.

Linear correlations of formation enthalpies/bulk modules and atomic volumes observed in Pt-Zr compounds by ab initio calculation

118 kinds of Pt-Zr phases were established and investigated by considering various structures. Then the related physical properties, such as structural stability, lattice constants, formation enthalpies, elastic constants and bulk moduli, are obtained by ab initio calculations. Based on the calculated results of formation enthalpies, the ground-state convex hull is derived for the Pt-Zr system. The calculated physical data would provide a basis for further thermodynamic calculations and atomistic simulations. For these Pt-Zr compounds, it is found there are a positive linear correlation between the formation enthalpies and atomic volumes, and a negative linear correlation between the bulk modules and atomic volumes.

基于在轨组装维护的多载荷协同观测卫星平台构型设计

针对高轨遥感卫星多载荷协同观测和一致测量应用需求,在前期总体技术方案研究的基础上,通过开展现有在轨组装航天器和高轨卫星公用平台的构型调研,提出了一种适用于多载荷协同观测需求的平台构型设计方案。平台利用CZ-5运载火箭发射并在轨展开,采用“网格式中心承力筒+板+桁架”式的总体构型,开展了主传力路径、贮箱承载结构、网格式中心承力筒等的细化设计工作,并进行了结构产品的初步设计,建立了平台结构整星的有限元模型。仿真分析表明:平台结构整星的各向一阶频率均能满足运载火箭的频率要求。基于标准化、通用化的平台接口设计,使其具备可扩展及可维修的能力,大大提升了平台鲁棒性。基于全网格筒的主承力设计,增强平台结构承载能力,并改善平台内部热环境。该设计方案可为基于在轨组装维护的高轨遥感大平台结构的设计提供有价值的参考。

E波段毫米波远距离通信技术研究

【目的】E/W波段毫米波频率覆盖60~110 GHz,频带资源丰富,具备大容量传输的潜力,与激光相比,E/W波段毫米波波束较宽,兼具方向性、抗干扰性和易于对准的优势,是海上远距离无线通信极具发展潜力的频段。然而,大气吸收和海面多径等近海面信道特征制约了E/W波段毫米波传输距离,导致E/W波段毫米波近海面传输存在瓶颈。文章聚焦海上远距离毫米波无线传输方向,运用微波光子技术提出了超宽带毫米波调制解调和变频系统结构,提高了毫米波变频和调制解调性能,进而研究近海面远距离传输系统中最优高阶调制格式,实现了大容量远距离传输。【方法】针对远距离通信系统中功率放大器会给信号带来非线性失真的问题,文章分析了固态功率放大器非线性特性对幅度相位调制(APSK)和正交幅度调制(QAM)等高阶调制格式性能的影响因素。研究了16APSK信号的最优分布方式、欧式距离和内外径比例,还通过等效功率实验测试,对比分析了16QAM和16APSK信号的抗非线性性能。【结果】实验证明,相对于QAM格式,APSK格式更加适用于远距离传输系统。【结论】文章基于16APSK格式,通过等效功率验证,实现了16 Gbit/s和等效34 km的远距离传输性能指标,为海上大容量远距离传输提供了高价值的技术手段。

基于四维非线性串扰模型的单跨无中继光传输多维调制设计

随着光通信速率需求的不断提高,光纤中的非线性效应成为了限制信道容量增长的主要因素.针对该问题,本文基于四维(Four-Dimensional,4D)非线性串扰模型和几何整形,提出了抗非线性4D调制设计方法.通过在加性高斯白噪声信道(Additive White Gaussian Noise,AWGN)和单跨无中继光纤传输系统中的仿真,详细比较了四类不同调制格式(包括分别针对AWGN信道和光纤信道设计的2D和4D调制格式)的传输性能.数值仿真结果表明,基于4D非线性串扰模型和4D空间联合优化的调制格式不仅有较高的线性整形增益还具有较好的非线性容忍性.以5通道的波分复用传输系统为例,优化得到的NL-4D-1024调制与传统正交幅度调制(QAM)和2D整形调制相比,可以分别减少0.8 dB和0.4 dB的发射功率.

基于联合残差网络和Bottleneck Transformer的调制格式识别方法

针对未来光网络链路中的传输需求,提出一种基于联合残差网络(ResNet)和Bottleneck Transformer(BT)的调制格式识别(MFI)方法。该方法结合ResNet和BT对6种不同调制格式的信号进行识别,并应用OptiSystem和TensorFlow对其进行仿真。仿真结果表明:在较宽的光信噪比(OSNR)范围内,所提方法的准确率达到了99.72%,并且能够很好地应对传输损伤的影响;与其它深度学习方法相比,该方法性能显著提升。

弹性光网络中基于DRL的RMSA算法

为了更好地解决弹性光网络(EON)的路由、调制格式与频谱分配(RMSA)问题,进一步降低网络阻塞率,提出一种基于深度强化学习(DRL)的RMSA算法。该算法在奖励设计中将考虑影响RMSA决策的资源占用度和频谱邻接度这2个指标,以鼓励智能体优先选择资源占用度低、频谱邻接度高的路径来建立光路,并对比该算法与其它算法在不同网络中的性能。仿真结果表明:与几种典型的DRL算法相比,所提算法的网络阻塞率更低。

一种用于可见光通信信号调制格式识别的改进YOLOv5s算法

针对可见光通信信号在传输中易受信道环境和背景噪声干扰等因素影响调制格式识别精度的问题,提出一种用于可见光通信信号调制格式识别的改进YOLOv5s(You Only Look Once)算法。首先,通过YOLOv5s算法网络输入端引入Mixup数据增强方式,将其与原网络中的Mosaic数据增强方式相结合,提升网络的鲁棒性,并增强算法在不同调制格式信号间的泛化能力;其次,将自适应空间特征融合(ASFF)引入到Neck网络中,充分提取不同层次的特征,提高检测精度。实验结果表明,在混合信噪比条件下,所提改进算法的平均精度均值(mAP)达到了0.903,比原始YOLOv5s算法提升了0.7%,且在信噪比为20 dB时mAP高达0.993。

前列腺素E2在骨形成中的作用机制

前列腺素E2(prostaglandin E2,PGE2)作为体内一种重要的生物活性物质,通过作用于前列腺素E受体(prostaglandin E receptor,EP),参与内环境稳态的维持。PGE2在骨代谢调控中发挥重要作用,在骨重建的过程中,调控成骨细胞介导的骨形成与破骨细胞介导的骨吸收,维持动态平衡。在骨形成方面,PGE2/EP轴通过神经调控、机械负荷调控、与体内其他细胞分子间的交互作用,促进成骨细胞增殖分化,维持骨稳态。因此,PGE2在以骨量异常为特征的疾病中发挥关键作用,可能是潜在的治疗靶点。本文对近年来PGE2在骨形成中的调控机制进行综述,并总结现有的临床应用。

电缆地层测试器探针模块常见故障分析

现有的电缆地层测试器探针模块故障统计归类和解决方案混乱,不利于制定电缆仪器维修保养标准化策略。通过梳理电缆设备的故障类型,针对电路故障、机械装配故障、电装工艺故障、电化学腐蚀故障逐一分析,提出具体解决方案;建立科学的三级保养制度,把易磨损的部位放在一级保养里面,按照PM1执行;把易污染的液压件放在二级保养里面,按照PM2执行;其余部位按照PM3执行。经过出海作业120余井次验证,设备可靠性有了极大提升。该分析从根源上有效管控了故障,做到了提前预防,对此类型仪器维保具有借鉴意义。

基于深度学习的智能调制格式识别

针对传统调制格式识别方法计算复杂度高、依赖过多先验知识等情况,文章提出了一种基于卷积神经网络的调制格式识别方法。该方法首先将无线电接收端的复数信号转换成4维矩阵,然后将预处理的数据输入到6层卷积神经网络中进行特征提取训练,最后通过softmax分类器实现调制格式分类。实验结果表明,在信噪比大于12 dB的条件下,该方法对BPSK,QPSK,8-PSK,16-QAM,64-QAM,PAM4,GFSK,CPFSK,B-FM,DSB-AM,SSB-AM共11种调制方式的平均识别率可达90%以上,且成功将算法部署在FPGA Zynq-7000芯片中。

Advanced modulation formats for underwater visible light communications [Invited]

In this paper, we present a detailed comparison of applying three advanced modulation formats including carrierless amplitude and phase modulation(CAP), orthogonal frequency division multiplexing(OFDM), and discrete Fourier transform spread orthogonal frequency division multiplexing(DFT-S OFDM) in underwater visible light communication(UVLC) systems. Cascaded post-equalization schemes are suggested to compensate the system impairments. For the first time, a two-level post-equalizer is presented to mitigate the nonlinear effect and improve the system performance of UVLC. The first post-equalization is based on a novel recursive least square Volterra. These modulation formats are all experimentally demonstrated with corresponding digital signal processing(DSP) algorithms. The experimental results show that single carrier modulations including CAP and DFT-S OFDM can outperform OFDM. Our experiment results show that up to 3 Gb/s over a 1.2 m underwater visible light transmission can be achieved by using DFT-S OFDM 64 QAM and CAP-64. The measured bit error rate is well under the hard decision-forward error correction(HD-FEC) threshold of 3.8 × 10^(-3).

Power distribution analysis for multiple modulation formats in an all-optical sampling wavelength division multiplexing system

An optimal power distribution analysis for an all-optical sampling orthagonal frequency division multiplexing(OFDM) scheme with multiple modulation formats including diferential phase shift keyed(DPSK), diferential quadrature phase shift keyed(DQPSK), and non-return-to-zero(NRZ) is proposed. The noise tolerances of different modulation formats are analyzed, and the optimal input power ratio between phase and intensity modulation formats for the best overall receiving performance is investigated under unchanged total input power. Moreover, this scheme can seamlessly coexist with the traditional WDM channel.

Modulation instability analysis of Rossby waves based on(2+1)-dimensional high-order Schrodinger equation

Modulational instability is an important area of research with important practical and theoretical significance in fluid mechanics,optics,plasma physics,and military and communication engineering.In this paper,using multiscale analysis and a perturbation expansion method,starting from the quasi-geostrophic potential vortex equation,a new(2+1)-dimensional highorder nonlinear Schrodinger equation describing Rossby waves in stratified fluids is obtained.Based on this equation,conditions for the occurrence of modulational instability of Rossby waves are analyzed.Moreover,the effects of factors such as the dimension and order of the equation and the latitude at which Rossby waves occur on modulational instability are discussed.It is found that the(2+1)-dimensional equation provides a good description of the modulational instability of Rossby waves on a plane.The high-order terms affect the modulational instability,and it is found that instability is more likely to occur at high latitudes.

Optimal modulation formats for 2560 km optical transmission with low power penalty

The production mechanism of non-return-to-zero(NRZ),return-to-zero(RZ)and carrier suppressed return-to-zero(CSRZ)was analyzed theoretically in this paper.We compared the transmission performance of CSRZ with RZ and NRZ formats at 10 Gb/s system by numerical simulation.And we simulated the transmission model constructed with Erbium-doped fiber amplifier(EDFA)as the solo amplifier and the chirped fiber Bragg grating(CFBG)as the solo dispersion compensator used in the system.A practical 8x10 Gb/s 2560 km transmitted experiment was conducted in straight line with these different modulation formats mentioned above and the experiment results show very good agreement with the result of computer simulation.The CSRZ format is more effective than other formats in the system,and involved only 2.5 dB power penalty cost in the practical 2560 km error-free experiment.The results also show that CSRZ will help to optimize the transmitted results and reduce the transmitted penalty further.

Investigation of Differently Modulated Optical Signals Transmission in HDWDM Systems

The authors＇ developed combined system model can be considered under the concept of next generation optical network （NGON） as a model for the future design of backbone networks. Such solution can be topical in the result of different telecom operators＇ optical networks convergence. In this case a necessity to transmit differently modulated signals over a single optical fiber even with different bit rates may occur. This research is performed with OptSim 5.2 simulation software that numerically solves nonlinear SchrOdinger equation. The authors have revealed the optimal parameter configuration for developed combined transmission systems and obtained in system＇s channels detected signals bit-error-rate （BER） correlation diagrams. They represent BER as a function from different system＇s parameters such as channel output power level, optical amplifier fixed output power level and system＇s channels allotment in C-band of ITU-T （Telecommunication Standardization Sector of the International Telecommunications Union） recommended spectral grid. As well as these obtained BER values were compared with the results for similar system, where instead of standard single mode fiber （according ITU-T Rec. G.652 D） optical signals are transmitted over non-zero dispersion shifted fiber （ITU-T Rec. G. 655）.

A novel bit mapping scheme for high-order polar coded modulation systems

In order to improve the spectrum efficiency of the high-order polar coded modulation systems, the polar code is used as the component code of the bit-interleave coded modulation(BICM) system, a novel bit mapping scheme is proposed considering of the channel polarization and successive cancellation(SC) decoding principle of polar codes as well as the unequal protection of equivalent channels by modulator. In this scheme, the frozen bits on the unreliable split channel are allocated to the equivalent channel with the low protection of the modulator, while the equivalent channels with the high protection are used to transmit the information bits. Thus, the error-correcting performance of polar codes is improved. Compared with some bit mapping schemes, the proposed bit mapping scheme only needs to divide and choose the parameters of the split channels reliability measurement, the complexity does not increase obviously, and simulation results show that the proposed scheme has the better performance under the quadrature amplitude modulation(QAM) modulation based on the Gray mapping.