A Positioning Method and Realization on Single Satellites in Different Orbits Using TDOA

The main geolocation technology currently used in COSPAS-SARSAT system is TDOA/FDOA or three-star TDOA,the principle is to determine the location of the signal source by using the difference in arrival time and frequency of the wireless signal between different receivers.Therefore,ground monitoring stations need to be equipped with more than two antenna receiving stations,and multiple satellites should be able to simultaneously relay the distress signal from the target source in order to achieve the geolocation function.However,when the ground receiving system has only one antenna receiving station,or the target source is in a heavily obscured environment,the ground side is unable to receive the forwarded signals from multiple satellites at the same time,which will make it impossible to locate.To address these problems,in this paper,a time-sharing single satellite geolocations method based on different orbits is proposed for the first time.This method uses one or several low-earth orbit satellites(LEO)and mediumearth orbit satellites(MEO)in the visible area,and the receiving station only needs one pair of receiving antennas to complete the positioning.It can effectively compensate for the shortcomings of the traditional TDOA using the same moment and have better positioning accuracy compared with the single satellite in the same orbit.Due to the limited experimental conditions,this paper tests the navigation satellite using different orbit time-sharing single satellite geolocations,and proves that the positioning method has high positioning accuracy and has certain promotion and application value.

Single channel source separation of radar fuze mixed signal based on phase difference analysis

A new method based on phase difference analysis is proposed for the single-channel mixed signal separation of single-channel radar fuze.This method is used to estimate the mixing coefficients of de-noised signals through the cumulants of mixed signals,solve the candidate data set by the mixing coefficients and signal analytical form,and resolve the problem of vector ambiguity by analyzing the phase differences.The signal separation is realized by exchanging data of the solutions.The waveform similarity coefficients are calculated,and the time鈥攆requency distributions of separated signals are analyzed.The results show that the proposed method is effective.

Single Neuron PID Control Based on Expert Experiences for Temperature Difference Control System of a Digester

Considering the temperature difference of displacement cooking characterized by severe non-linearity, large time delay, and real-time control, a cascade PID adaptive control strategy composed of a single neuron is proposed to ensure cooking temperature uniformity. The control strategy introduces expert experiences to adjust the single neuron gain K, while a single neuron PID self-learning and adaptive ability, as well as cascade advantage can be combined to realize the real-time and fast temperature difference control. In the Simulink, the s-function of this control strategy is used to carry out a dynamic simulation experiment with temperature difference characteristics and verify the robustness and response to model mismatch. Compared to conventional temperature difference-flow PID cascade control and single neuron PID cascade control, this control strategy has better robustness and stronger adaptability. The results of real-time control on the THJSK-1 experiment platform indicate this control strategy is feasible.

Research on Kalman Filtering Algorithmfor Deformation Information Series ofSimilar Single-Difference Model

Using similar single-difference methodology(SSDM) to solve the deformation values of the monitoring points, there is unstability of the deformation information series, at sometimes.In order to overcome this shortcoming, Kalman filtering algorithm for this series is established,and its correctness and validity are verified with the test data obtained on the movable platform in plane. The results show that Kalman filtering can improve the correctness, reliability and stability of the deformation information series.

A Doppler Location Method Based on Virtual Path Difference

This paper presents a Doppler passive location method for moving targets with fixed single station using the Doppler frequency shift and time difference information.First,based on the relationship between frequency shift and path difference,the virtual path difference is calculated from the measured value of Doppler frequency shift by means of mean value correction.Then,under the assumption that the target is moving at a constant speed along a straight line,two coaxial virtual double base arrays are constructed by using the moving track of the moving target based on the method of fixed period time difference.On this basis,the moving distance of the moving target can be calculated by using the ratio relationship between the frequency difference and the radial distance between the two adjacent detection points in the middle of the array,and the linear solution of the two double base path difference positioning equations.At this point,the relative coordinate position of the moving target can be obtained by directly using the linear solution of the double base path difference positioning equation again.

False Positives Caused by Single Primer in DDRT Analysis of Soybean

[Objective] The aim was to explore the reasons of false positives in Different Display Reverse Transcription（DDRT）analysis.[Method] Soybean varieties ＂Jilin 30＂ and ＂Tongnong 13＂ were used as materials to carry out analysis on false positives in DDRT analysis.[Result] An important origin of false positives appeared in DDRT analysis was the non-specific amplification caused by the combination of single primer and cDNA.The parallel PCR test of single primer should be set so as to verify whether the obtained fragments were the false positives or the PCR productions combined with single primer.[Conclusion] This study had provided basis for improving the success rate of DDRT experiment.

On an Expression of Extraction Constants without the Interfacial Equilibrium-Potential Differences for the Extraction of Univalent and Divalent Metal Picrates by Crown Ethers into 1,2-Dichloroethane and Nitrobenzene

An idea on interfacial equilibrium-potential differences () which are generated for the extraction of univalent metal picrate (MPic) and divalent ones (MPic2) by crown ethers (L) into high-polar diluents was improved. These potentials were clarified with some experimental extraction-data reported before on the M = Ag(I), Ca(II), Sr(II) and Ba(II) extraction with 18-crown-6 ether (18C6) and benzo-18C6 into 1,2-dichloroethane (DCE) and nitrobenzene (NB). Consequently, it was demonstrated that the? values from the extraction-experimentally obtained logKD,Pic ones are in agreement with or close to those calculated from charge balance equations in many cases, where the symbol, KD,Pic, denotes an individual distribution constant of Pic﹣ into the DCE or NB phase. Also, it was experimentally shown that extraction constants based on the overall extraction equilibria do not virtually contain the? terms in their functional expressions.

白花前胡单株类型的HPLC指纹图谱研究

目的:探索白花前胡栽培群体单株的差异性。方法:采集单株前胡观察农艺性状;采用高效液相色谱法(HPLC)建立白花前胡单株类型指纹图谱;运用中药色谱指纹图谱相似度评价系统结合聚类分析和主成分分析方法分析差异性。结果:叶型有阔叶、狭叶和两者之间的中间型三类,叶色主要是绿色、淡红色、淡紫红色、黄绿色;建立了16批单株白花前胡HPLC指纹图谱,色谱图相似度为0.545~0.999,聚类分析和主成分分析表明,白花前胡分为两大类,其引起差异性的特征成分主要为白花前胡甲素、白花前胡乙素。结论:该研究建立的白花前胡的化学成分HPLC指纹图谱能较好地分析其栽培群体单株的差异性,可为白花前胡的种质资源挖掘和利用提供参考。

焊接方法对铝合金焊接接头微弧氧化色差的影响

目的分析铝合金焊接接头微弧氧化过程中色差产生的原因。方法采用单激光和激光-MIG复合焊2种焊接方法焊接2A12铝合金,利用RGB值定性描述不同焊接试样的色差差异大小,采用金相、SEM和微区XRD观察2A12铝合金单激光和激光-MIG复合焊接头微弧氧化前后的组织、微观形貌和表面物相组成。结果经微弧氧化处理后,2A12铝合单激光焊焊件的焊缝和母材之间无明显色差,2A12铝合金激光-MIG复合焊焊件的焊缝和母材之间存在明显色差,结合金相组织、表面和截面的SEM形貌以及表面EDS和XRD测试分析结果可知,成分和表面熔融物颗粒的大小不同是铝合金焊接接头微弧氧化色差形成的主要原因,焊接接头的组织对铝合金焊接接头微弧氧化色差的产生没有影响。结论单激光焊接接头微弧氧化后的氧化色差较激光-MIG复合焊接头的小;铝合金(2A12)焊接接头产生氧化色差主要是因为焊接接头的成分和表面熔融物颗粒大小不同,而组织对色差无影响。

单幅图像局部特征分层模糊挖掘算法仿真

为了能够深入获得图像纹理特征信息,提高后续数据识别精准度。因此,提出了单幅图像局部特征分层模糊挖掘算法。通过直方图均衡化方法,将图像中灰度值集中到对应灰度等级区域。由不均匀分布向均匀分布状态转换,拓展像素的灰度动态范围。分析图像局部特征复杂度与差异度,求出相邻模板灰度等级,得到局部复杂性和差异度矩阵,采用Laplace算法对图像局部特征推荐分类,根据推荐级别分层模糊挖掘所选特征,以此实现对单幅图像的局部特征分层模糊挖掘。通过实验证明,所提算法可准确挖掘出图像特征,不同层级纹理信息都完整,且挖掘时间保持在0.25s内。

普适型GNSS双频数据的周跳探测与修复方法

通过分析宽巷相位减窄巷伪距和无几何距离组合周跳探测方法存在的问题,提出一种考虑GNSS卫星高度角因子且适用于普适型GNSS观测数据的周跳探测方法。在探测出周跳发生的历元位置后,利用基于空间搜索和目标函数最小准则的方法进行周跳修复,并选取安置在甘肃临夏公路旁一滑坡隐患处的普适型GNSS接收机所观测的不同高度角卫星数据对提出的周跳处理方法进行验证。结果表明,该周跳探测与修复方法能实现不同高度角卫星载波相位数据中周跳的准确探测与修复,并减弱GNSS数据观测误差对周跳检验量的影响,对普适型GNSS观测数据的周跳探测与修复具有可行性。

碳交易政策对城市能源利用效率的影响及机制

能源利用效率提升是实现碳达峰战略目标的重要抓手。本文将能源利用效率区分为单要素能源生产率与绿色全要素能源效率,以2004~2022年我国284个地级市为研究样本,运用双重差分、连续型双重差分等方法考察检验碳交易政策对试点城市能源利用效率的影响及机制。结果显示:碳交易政策能显著提升城市单要素能源生产率与全要素能源效率,且政策效应随年份推移越发显著。机制分析表明:碳价上升有助于改善城市单要素能源生产率与全要素能源效率;碳交易政策能通过能源资源错配的纠正改善城市单要素能源生产率与全要素能源效率,而绿色技术创新的中介影响为负。碳交易政策有助于提升非资源型城市、非老工业基地城市单要素能源生产率与全要素能源效率,而对老工业基地城市单要素能源生产率存在抑制作用。本文基于城市能源利用效率提升的视角,为全国范围碳交易市场建设提供政策启示。

基于双折射晶体透镜的自干涉全息成像系统

该文介绍了采用α–BBO双折射晶体透镜进行分光和光程差补偿方法,以及使用偏振相机进行单次采集的自干涉全息成像方法。该方法不需要使用额外器件补偿共轴干涉光路的光程差,适用于非相干白光照明情况下日常物体的全息图采集与图像重建。该文推导了再现距离与放大率等重要参数,并在此基础上,搭建了单发成像系统,还进行了实验验证。实验通过单次曝光采集了LED灯组的四幅不同偏振态全息图,并用四步相移法得到复振幅全息图,最后通过图像重建算法反演计算获得准确的再现图像。实验验证了基于α–BBO双折射晶体透镜的单次曝光自干涉全息成像方法的三维成像能力。

一种基于差异矩阵的光谱复原方法

单透镜成像技术基于计算成像技术发展而来。利用单片透镜构成的光学系统代替传统复杂的光学系统,利用后端的算法处理替代前端的光学处理,不仅简化了光学系统复杂度,而且能够获得满足需求的图像。目前,国内外对于单透镜成像技术在成像光谱领域中的研究较少,因此,开展基于单透镜成像技术的图谱信息获取研究具有较大的研究价值及意义。文章针对单透镜成像光谱仪的混叠图谱数据,提出了1种基于差异矩阵的光谱复原方法。当只考虑光谱信息时,只需对轴上数据进行采集,再根据获取的不同位置处不同波长的强度信息,计算得到差异系数,构建差异矩阵,利用最小二乘法进行求解,即可实现光谱的复原。通过仿真及实验验证,利用SCC及SMSE进行质量评价,验证了上述方法的正确性及可行性。

北斗实时百皮秒级单差时频同步方法

高精度时频传递与时间同步服务已成为全球导航卫星系统应用领域的研究热点,国内外学者围绕GNSS高精度时频同步模型算法及相关应用等方面开展了诸多研究。本文提出基于载波相位的差分高精度时间传递模型,实现基于北斗卫星导航系统的实时百皮秒级单差时频同步。以中国计量科学研究院的光纤链路为参考,北斗时间同步精度优于时频同步系统的实时秒脉冲时间同步精度优于100 ps;在7 d的测试时段内,链路的时间稳定度优于70 ps;链路频率万秒稳定度可达10-15量级,频率长期稳定度可达10-16量级。利用BDS进行单差时频同步的频率稳定度与GPS相当,对开展BDS在时频领域的下一步推广应用提供重要的参考意义。

适应波达时刻不确定性及较低采样率的新能源送出线路就地暂态量主保护判据

不对称接地故障占所有线路故障的90%以上,接地距离保护在应对此类故障方面发挥了不可替代的作用。随着新能源高比例渗透,各种传统单端工频量保护性能显著下降已成为共识。基于故障分量线模和零模波速差的保护判据理论上仅需利用到故障初始行波到达时刻信息,是一种原理简单可靠的单端量快速保护判据,已经在直流电网中成功实践。但在尝试将这类保护应用于交流电网时发现,受波头前陡较缓而难以精确定位波到时刻、依赖高采样率等诸多不利因素影响,存在过大的模糊判别区,除了特长线路外,对绝大部分线路几乎没有应用可行性。波到时刻的精准辨识是一个复杂的非线性问题,利用人工智能的方法进行辨识是一条可行的解决思路,对此,该文提出一种新的单端暂态量主保护判据。首先,分析波达时刻与波形关系,并指出这种关系能够采用机器学习来映射;其次,引入高斯过程回归(Gaussian process regression,GPR),在对初始行波数据进行预处理得到样本集后,输入GPR预测模型进行训练;然后,依据模型评估指标得到最优训练模型以输出高可信性的线-零模波达时差,据此实现了基于行波模量传输时间差的保护判据;最后,在利用PSCAD仿真验证所提保护判据有效性和普适性的基础上,进一步利用现场实测数据对判据进行测试,验证其实用性。该文工作为新能源交流系统下单端暂态量保护的性能提升提供新的解决思路。

局部组合降雨空间插值方法适应性研究

【目的】对于同一流域内部不同子区域高程、坡度等地形要素差别较大的情景,采用同一降雨空间插值方法,将显著影响降雨插值结果的精度。为降低流域下垫面差异对降雨插值精度的影响,【方法】以岸堤水库流域为例,采用克里金法(Kriging)、反距离权重法(IDW)法和自然邻域法(NN)法及其两两组合,共9种方案进行分析,通过对比不同降雨插值方法及其组合和不同雨量站点数量情景下的降雨插值效果,对组合降雨空间插值方法进行适应性研究。【结果】结果显示:(1)局部组合和整体单一插值方法插值后所得降雨量在梯度变化、空间分布和子区域分界线两侧有较大差异,局部组合插值的结果优于整体单一插值;(2)岸堤水库流域东北区域采用IDW法、西南区域采用NN法方案插值后不同场次降雨和不同站点的平均MRE值为1.11%,极大值和极小值下分别为1.51%和5.30%,精度最高,效果最优;(3)同一插值方案下,均匀减少插值站点,插值方法精度降低明显。【结论】研究结论如下:在雨量站数量一定的情况下,流域空间地形差异明显、多种插值方法效果相当时,局部组合插值能够综合多种插值方法的特点,使插值方法更适应于流域的局部特性并提升插值精度。本研究对于解决流域地形地貌空间分布差异显著的降雨空间插值问题,具有一定的理论意义和参考价值。

基于运动单站的LTE辐射源定位技术

长期演进(LTE)信号具有覆盖范围广泛、带宽大、自相关特性良好、抗衰落能力强及发射功率大等诸多有利于定位的优点,是一种可用于定位的主要机会信号。基于LTE信号的定位方法需要利用辐射源的位置信息进行解算,在非合作环境中获取基站的位置信息是使用LTE信号进行定位的基础。提出了一种利用移动单站获取LTE辐射源位置的定位方法,以到达时间差(TDOA)为观测量,建立了包含钟差校准的定位模型,并从单站的运动轨迹和初始点选取两个方面分析了算法的收敛性和定位精度。通过行人以及车载两种方式,在实际环境中对定位方法的性能进行了测试,实验结果表明,该方法的定位误差小于10 m。

玉米花粉离体萌发的研究

本研究旨在探究不同培养基组分对玉米花粉萌发的影响,并筛选出最适宜玉米花粉离体萌发的培养基。通过单因素实验,比较了不同浓度的蔗糖、葡萄糖、乳糖、麦芽糖、硼酸和氯化钙对多个玉米品种花粉活力的作用。结果表明,含有0.35 mol/L蔗糖、0.85%琼脂、0.01%硼酸和0.03%氯化钙的培养基能够使对照花粉达到最佳萌发效果,为51.6%。然而,该培养基对于不同品种的玉米花粉影响差异显著,实验中8个玉米品种的花粉萌发率在1.8%~21%之间,显示出‘e12’品种的花粉萌发最为适宜,而‘e11’品种的花粉萌发则不适宜。本研究筛选出的最适培养条件为玉米花粉离体萌发机制的研究及玉米遗传育种提供了重要的理论依据和参考。

森林结构复杂度对单木分割精度的影响——以田横岛为例

单木分割对于森林资源调查具有重要的意义,不同结构复杂度的森林单木分割算法的选择以及分割参数的选取对分割精度有着很大的影响。以山东田横岛为研究区,基于无人机正射影像与激光雷达数据,首先提取海岛森林典型植被二维与三维特征,然后利用随机森林算法对不同树种的树木进行分类,最后基于分类后的点云数据,选取不同结构复杂度的森林样地,对比分析聚类算法、层堆叠算法、分水岭算法在不同复杂度林区的适用性。结果表明:(1)随机森林算法结合单木二维、三维特征可有效对混交林树木进行分类,模型总体的精度为94.51%,Kappa系数为0.9038;(2)聚类算法对结构简单的林区具有更高的分割精度(F=96.41),但依赖于分割参数的选取;面对复杂单木集群,分水岭算法总体得分波动最小(ΔF=14.56),表现出较强的稳定性;(3)混交林预先进行树种分类可有效改善单木分割环境,相比于直接进行单木分割,聚类算法、层堆叠算法、分水岭算法的分割精度均得到不同程度的提升(ΔF_(1)=10.06,ΔF_(2)=9.51,ΔF_(3)=12.6)。