Star Point Energy Center Correction of Star Simulator Based on Polar Coordinates

In this paper,various aberrations have been analyzed.Not only the effects of aberration on geometrical center position are taken into account,but also the deviation of displayed star position energy center caused by aberration is analyzed.These two aspects have been taken into comprehensive evaluation and star position correction.The correction method based on polar coordinates is proposed,and cumbersome partition correction and calculated quantity based on two-dimensional coordinates can be simplified.The experimental results show that the correction processing based on polar coordinates is simpler and easier compared with any other correction methods.In addition,the correction results are significantly more accurate.

Correction: c-Myc-drivenn glycolysis polarizes functional regulatory B cells that trigger pathogenic inflammatory responses

Correction to:Signal Transduction and Targeted Therapy https:/l doi.org/10.1038/s41392-022-00948-6,publishedonline18 April2022 In the process of collating the raw data,the authors noticed an inadvertent error occurred in Supplementary Fig.5d that needs to be corrected after online publication of the article 1.

High-speed polarization mode dispersion compensation in a 43-Gb/s RZ-DQPSK transmission system over 1200 km of standard single-mode fibre

This paper reports that the designed optical polarization mode dispersion compensator shows a good performance under the real-time variation of differential group delay, state of polarization and principal state of polarization in a （40×43）-Gb/s dense-wavelength-multiplexing, 1200-km enhanced return-to-zero differential-quadrature-phase-shift- keying （RZ-DQPSK） system. The polarization mode dispersion tolerance of the system is improved by 26 ps using the optical polarization mode dispersion compensator. The short and long time stabilities are tested with the bit error ratio recorded.

一种基于Polar码的可抗差错图像传输方法

Polar码是第一种理论上被严格证明能达到香农限的信道编码方法。结合Polar码的构造特点,提出了一种基于Polar码的可抗差错的图像传输方法,将传输图像进行离散变换后获取的频率分量与Polar码极化后信道的可靠性一一对应,然后进行编码传输。仿真结果表明,新构造的图像传输系统,能以较少的信息完成图像传输,同时达到较高的传输质量,具有良好的可抗差错性和较高的传输效率。

A DFT+U study of the structures and reactivities of polar CeO_2(100) surfaces

Density functional theory calculations corrected by on-site Coulomb interactions were carried out o study the structures of polar CeO2 （100） surfaces as well as activities during catalytic CO oxidation. The stabilities of various CeO2 （100） termination structures are discussed, and calculated energetics are presented. The most stable Ce〇2 （100） surface was obtained by removing half the outermost full layer of oxygen and the surface stability was found to decrease as the exposed oxygen concentration was increased. Assessing the reaction pathways leading to different final products during CO oxidation over the most stable CeO2 （100） surface, we determined that the formation of carbonate species competed with CO2 desorption. However, during CO oxidation on the less stable CeO2 （100） surfaces having more exposed oxygen, the CO is evidently able to react with surface oxygen, leading to CO2 formation and desorption. The calculation results and electronic analyses reported herein also indicate that the characteristic Ce 4/ orbitals are directly involved in deter-mining the surface stabilities and reactivities.

Aberration-corrected scanning transmission electron microscopy for complex transition metal oxides

Lattice,charge,orbital,and spin are the four fundamental degrees of freedom in condensed matter,of which the interactive coupling derives tremendous novel physical phenomena,such as high-temperature superconductivity（high-T_c SC） and colossal magnetoresistance（CMR） in strongly correlated electronic system.Direct experimental observation of these freedoms is essential to understanding the structure-property relationship and the physics behind it,and also indispensable for designing new materials and devices.Scanning transmission electron microscopy（STEM） integrating multiple techniques of structure imaging and spectrum analysis,is a comprehensive platform for providing structural,chemical and electronic information of materials with a high spatial resolution.Benefiting from the development of aberration correctors,STEM has taken a big breakthrough towards sub-angstrom resolution in last decade and always steps forward to improve the capability of material characterization;many improvements have been achieved in recent years,thereby giving an indepth insight into material research.Here,we present a brief review of the recent advances of STEM by some representative examples of perovskite transition metal oxides;atomic-scale mapping of ferroelectric polarization,octahedral distortions and rotations,valence state,coordination and spin ordering are presented.We expect that this brief introduction about the current capability of STEM could facilitate the understanding of the relationship between functional properties and these fundamental degrees of freedom in complex oxides.

基于ECOC平衡随机森林的雷达降水粒子分类

针对数据不平衡情况下的降水粒子分类问题,提出了一种基于纠错输出码(error correcting output code,ECOC)平衡随机森林的双偏振气象雷达降水粒子分类方法。首先,将多类别降水粒子数据集编码为多个二分类数据集;然后,对二分类数据集进行有放回的平衡重采样,构建多棵分类回归树;最后,利用所有的分类回归树联合进行降水粒子分类。对实测数据的处理结果表明,所提方法能够在保证总体准确率较高的情况下,大幅提高少数类的分类效果。

航空偏振辐射计偏振精度验证及带外响应分析

为满足航空平台图像大气校正的应用需求,在可见近红外至短波红外波段,同时获取大气多谱段偏振辐射信息,研制了一种用于航空轻量化的偏振探测仪器,航空偏振辐射计。首先,对仪器进行系统描述与光学组件简介,并给出仪器的主要技术参数,其次为保证仪器数据的可用性与参数反演精度,仪器装调之后,在实验室进行绝对辐射定标及偏振测量精度验证。研究结果表明:航空偏振辐射计的绝对辐射定标不确定度优于2.51%,各偏振波段对0.2线偏振度目标的偏振测量精度优于0.16%。同时对490 nm波段偏振精度不理想的情况进行分析,并使用单色仪系统验证其受带外响应影响,通过对比实验验证,针对490 nm波段的偏振通道,去除带外响应影响后,其偏振精度从2.29%提升至0.06%。

万宁双偏振天气雷达降水产品参数本地化及评估

为提高万宁双偏振天气雷达(CINRAD-SAD型)定量降水估测产品的准确性,使用万宁雷达探测半径内3部天气现象仪(WUSH-PW型)在2022年6次普通降水和3次台风降水的数据资料,采用非球形粒子的散射模型(T-Matrix)对万宁雷达的参量Z_(H)、Z_(DR)、K_(DP)进行了模拟,最后用最小二乘法拟合出了降水估测公式的本地化参数。分别对使用默认参数和本地化参数的1 h雷达定量降水估测产品(OHP)进行了总体评估、分降水量评估、分距离评估,还对使用雨量计订正后的降水产品进行了总体评估。评估结果表明:(1)使用本地化参数比默认参数计算得到OHP估测准确率提高了29.66%(OHP单偏振78号产品)和14.47%(OHP双偏振169号产品)。(2)使用本地化参数比默认参数在各个降水量级的估测准确率均有所提高,最多提高了36.82%。(3)使用本地化参数比默认参数在各个距离段的估测准确率均有所提高,最多提高了32.33%。(4)经雨量计订正后的本地化参数降水产品准确率均达到了90.00%以上,平均偏差比接近1,可作为降水真值使用。

基于奇偶校验极化码的量子密钥纠错方法

为了提升量子密钥分发(QKD)中密钥纠错的性能,提出了一种基于奇偶校验极化码的量子密钥纠错方法。该方法在密钥纠错过程中引入了奇偶校验极化码,并优化了奇偶校验编码策略,利用密钥极化编码后生成的奇偶校验信息完成密钥纠错。仿真结果表明:与现有的基于极化码的密钥纠错方法相比,该方法可以在相同的量子比特误码率下获得更高的纠错效率;当实际QKD实验中的量子比特误码率为0.01048时,其纠错效率达到1.34,安全成码率可达1319 b/s。

基于双目视觉的三维场景图像表面重建算法

在三维场景图像中,像素色度不均匀会影响图像的视觉表现效果,维持像素色度的均匀分布是提升图像视觉表现效果的有效方法。为满足实际应用需求,大幅提升三维场景图像的视觉表现效果,提出一种基于双目视觉的三维场景图像表面重建算法。首先,确定视觉相机的内参、外参标记结果,通过极线校正双目图像的处理方式,完成基于双目视觉的三维场景图像标定;然后,求解像素代价聚合条件,根据像素节点的三维视差推导图像表面的重建表达式,完成基于双目视觉的三维场景图像表面重建算法的设计。实验结果表明,双目视觉技术作用下,三维场景图像的像素色度呈现出较为均匀的分布状态,符合提升图像视觉表现效果的实际应用需求。

5G网络纠错技术浅析

信道编码是网络通信纠错技术的首要手段,直接影响无线通信系统的效率和质量。该文通过介绍目前主流信道编码的技术原理、编解码方式,结合模拟仿真各自编码效率等方式,分析各编码方案的优劣,指出LDPC码和极化码在5G网络中应用的优势和重要性。

An automatic seismic signal detection method based on fourth-order statistics and applications

Real-time, automatic, and accurate determination of seismic signals is critical for rapid earthquake reporting and early warning. In this study, we present a correction trigger function（CTF） for automatically detecting regional seismic events and a fourth-order statistics algorithm with the Akaike information criterion（AIC） for determining the direct wave phase, based on the differences, or changes, in energy, frequency, and amplitude of the direct P- or S-waves signal and noise. Simulations suggest for that the proposed fourth-order statistics result in high resolution even for weak signal and noise variations at different amplitude, frequency, and polarization characteristics. To improve the precision of establishing the S-waves onset, first a specific segment of P-wave seismograms is selected and the polarization characteristics of the data are obtained. Second, the S-wave seismograms that contained the specific segment of P-wave seismograms are analyzed by S-wave polarization filtering. Finally, the S-wave phase onset times are estimated. The proposed algorithm was used to analyze regional earthquake data from the Shandong Seismic Network. The results suggest that compared with conventional methods, the proposed algorithm greatly decreased false and missed earthquake triggers, and improved the detection precision of direct P- and S-wave phases.

X波段双线极化雷达反射率的衰减订正

X波段雷达虽然其衰减较S和C波段雷达严重,但是由于其易于移动等特点,还在各国推广应用,为了反演获得可靠的降水分布,X波段雷达数据需要进行衰减订正。本文提出一种基于气象目标和单位差分传播相移KDP特性的衰减订正方法。KDP由前向和后向两个分量组成,为了计算KDP,必须分离这两个分量以及消除其他随机噪声的影响。本文引进了一种最优化自回归数据滤波算法——卡尔曼滤波来分离这两个分量和消除其他随机噪声。这种方法效率高、实用性强,同时可以用于其他雷达信号的处理。比较衰减订正结果,发现使用卡尔曼滤波方法处理后的差分传播相移所进行的反射率衰减订正具有较高的稳定性。

三通道偏振成像系统及系统误差校正方法

为了解决现有偏振成像系统难以满足目标检测和跟踪等实时图像处理领域的要求,提出一种实时三通道偏振成像系统,并对该系统存在的视场差异和非一致性误差提出了校正方法.该系统采用三个独立通道采集0°、60°和120°方向上的偏振图像,针对三个独立通道之间存在的视场差异提出了采用尺度不变特征转换配准法进行校正的方法;同时针对三个独立通道之间的灰度响应非一致性现象,根据积分球的退偏特性和探测器的线性响应模型,利用积分球产生完全非偏振光对灰度响应非一致性误差进行了校正.对比实验证明:1)本文提出的三通道偏振成像系统进行校正后的成像效果能够接近单通道偏振成像系统的水平;2)该系统能够在实时采集图像的同时,克服了多通道带来的偏振图像质量下降问题,提高了实用性.

分时偏振光谱测量系统的起偏效应校正

针对实验室偏振光谱测量系统短波红外起偏效应大、测量偏差大的问题,建立了系统目标斯托克斯校正模型,提出了该模型中相关系数的测量方法,从而实现了系统偏振效应的精密校正。首先分析了实验室常用的低成本分时偏振光谱测量系统存在的主要问题及起偏效应的来源。然后根据偏振传输理论,将系统中起偏效应较大的波谱仪等效为检偏系统,建立了目标偏振信息的校正模型,并通过与理想模型的对比验证了模型的正确性。最后针对本测量设备,为提高校正系数的测量精度,在解析法的基础上提出了一种更精确的拟合法。实验结果表明,本方法的校正精度高于0.5%,满足实验室中对目标偏振信息处理的精度要求,对偏振光谱测量系统的研制和标定具有指导意义。

二维倾斜地形对大地电磁资料的影响与地形校正

二维倾斜地形影响，主要使ＴＭ极化模式的视电阻率降低。数值模拟结果证明，倾角小于１０°时，地形影响可以忽略，随着倾角的增大，地形影响急剧加强。同时，倾斜地形影响与周期有关，周期愈长，影响愈甚，而且，当倾角增大时，开始出现显著影响的周期提前。利用带地形均匀半空间与水平均匀半空间的电磁响应，计算出校正系数，进而可以消除或降低地形影响。

微偏振片阵列成像的非均匀校正研究

针对传统的非均匀校正算法难以校正偏振成像的非均匀问题,提出了一种新的矩阵校正算法。分析了偏振成像与非偏振成像的非均匀性的不同表现,阐述了微偏振片阵列成像的非均匀产生机理,指出了采用非偏振成像非均匀校正方法的失效原因。在构建偏振成像系统对入射偏振光源的响应模型基础上,提出了矩阵校正法。实验部分给出了矩阵校正法对均匀偏振场本底图像和信息丰富场景图像的校正效果,定量分析结果表明,矩阵校正法将均匀本底图像的非均匀性降至校正前的10%左右。

X波段双线偏振气象雷达反射率的衰减订正

X波段天气雷达的强衰减是影响其探测精度与应用推广的主要问题。本文旨在寻求适用于降水过程中对X波段双偏振雷达进行衰减订正的一种方法。在订正前先对雷达数据进行了质量控制和预处理;在分析了国内外已有订正方法的基础上,选择并改进了自适应约束算法作为雷达反射率进行衰减订正的方法;最后进行方法的效果验证。既对衰减订正前后反射率与同时段S波段雷达反射率作对比,又对偏振参数KDP～ZH、AH～ZH之间关系的变化进行分析,不仅如此,还直接与地面降水实况作比较等。分析表明,对X波段双线偏振雷达进行反射率衰减订正后的效果显著优于订正前,特别是,当存在较大范围(含对流型)降雨时,采用此种订正方法可以明显提高降水的估测精度。