Adaptive detection of range-spread targets in homogeneous and partially homogeneous clutter plus subspace interference

Adaptive detection of range-spread targets is considered in the presence of subspace interference plus Gaussian clutter with unknown covariance matrix.The target signal and interference are supposed to lie in two linearly independent subspaces with deterministic but unknown coordinates.Relying on the two-step criteria,two adaptive detectors based on Gradient tests are proposed,in homogeneous and partially homogeneous clutter plus subspace interference,respectively.Both of the proposed detectors exhibit theoretically constant false alarm rate property against unknown clutter covariance matrix as well as the power level.Numerical results show that,the proposed detectors have better performance than their existing counterparts,especially for mismatches in the signal steering vectors.

A Novel Inter-Carrier Interference Cancellation Scheme in Highly Mobile Environments

In the current multi-carrier communications,Orthogonal Frequency Division Multiplexing(OFDM)is widely considered as a leading technology.For mobile applications,however,the orthogonality between subcarriers is deteriorated by Doppler frequency shift,which will introduce serious subcarrier phase rotation in the received signals and degrade the system performance.Thus,a method of differential grouping weighted symmetry data-conjugate(DWSCC)have been previously presented to obtain a better inter-carrier interference(ICI)suppressing effect and Bit Error Rate(BER)performance with no loss of spectral efficiency.In this paper,a novel scheme applying a completely different method of subcarrier interactive mapping is put forward.By mapping two different symbols which are both conjugated or multiplied by a complex weighting factor onto a pair of symmetric subcarriers,the presented scheme can greatly reduce the influence of subcarriers phase rotation caused by Doppler frequency shift in highly mobile environments.Analysis and simulation results indicate that comparing with the DWSCC method,our formulated scheme can not only maintain the spectrum utilization with no loss,but also have the advantages of an improvement on reduction effect and BER performance as well as a lower computational complexity in highly mobile environments.

草地植物生殖分配研究进展

植物生殖分配调控着植物营养生长与生殖生长的平衡,从而影响种群的更新速度,最终改变群落结构及演替方向。因此,研究植物生殖分配对草地生态系统稳定和可持续发展至关重要。本文通过文献综述方法,系统地梳理了草地生态系统植物生殖分配的相关研究理论及影响因素,学者们先后基于最优控制理论、生活史理论和生物量分配理论提出光合补偿机制、养分循环假说、时间限制假说、r/k策略、资源可用性假说等,以解释自然环境因素、植物自身因素和人为干扰因素等调控植物生殖分配的机制。然而,草地植物对诸多因素(植株形态性状、自然灾害、放牧、刈割、外源养分添加等)的生殖分配响应仍存在争议,且复杂因素(气候变化、生境条件、植物间竞争等)及多因素协作的过程和驱动机制不清晰。基于此,建议从多维度解析草地植物生殖分配策略及驱动机制,以期为促进草地生态系统更新及正向演替、提高草地资源利用率的研究提供理论依据。

植物群落沿海拔梯度的分布规律——以滇西北哈巴雪山东坡矿场路为例

[目的]探究哈巴雪山东坡矿场路植物群落在遭受破坏后,植物群落沿海拔的演替规律及种群的更新能力。[方法]以哈巴雪山东坡矿场路沿海拔梯度设置23个样方,分析哈巴雪山东坡矿场路植物群落生物多样性指数垂直分布格局。[结果]23个样地中,乔木27种,灌木65种,草本196种。物种丰富度呈明显的单峰分布格局,峰值最大出现在中海拔群落,乔木层和草本层植物的物种丰富度随海拔先升高后降低,而灌木层植物的物种丰富度随海拔的上升呈明显下降的格局。α多样性随海拔梯度的变化与物种丰富度相似,β多样性基本也符合单峰格局,但是受矿厂区干扰峰值波动起伏较大。[结论]海拔梯度、人为干扰、小地形破坏对群落物种多样性都有着重要影响。

天津宝坻新台FHD-2B质子矢量磁力仪运行质量和干扰分析

以天津宝坻新台FHD-2B质子矢量磁力仪为例,分析了其运行质量和干扰情况。从观测数据的连续率和有效率,观测数据背景噪声和数据一致性,数据变化动态及主要干扰等方面进行了分析研究。结果表明:宝坻新台地磁FHD观测数据的连续性和有效率较高;仪器背景噪声较大,高于全台网噪声平均值;在日常观测中,主要受到高压直流输电、地磁暴和主机故障等干扰。研究结果对同类台站同类仪器数据分析应用具有借鉴意义。

腔体环境下数据链设备电磁环境效应试验研究

腔体电磁环境具有电场分布不均匀、对空间加载敏感、难以准确度量等特点,腔体环境下的电子设备电磁环境效应试验不应采取传统的确定性试验方法。针对此问题,提出了使用边界形变混响室开展腔体内电子设备电磁环境效应概率试验的方法,以无人机数据链设备为受试对象,试验研究了连续波电磁环境对无人机数据链设备的电磁干扰阈值和干扰概率,为腔体环境下电子设备电磁环境效应研究提供了一个新的思路。

水面无人艇的模糊建模方法研究

为更好地应对水流、风力等外界干扰,提高航行的安全性和可靠性,研究水面无人艇的模糊建模方法。从惯性和艇体坐标系的2个角度,建立水面无人艇运动数学模型,全面描述无人艇的运动状态,包括位置、速度、加速度、航向角等关键参数;通过考虑风、浪、流这3个方面的干扰因素,建立水面无人艇环境干扰模型,得到总扰动力矩;以水面无人艇运动数学模型为基础,获取无人艇距离与航向角的偏差,作为模糊神经网络PID算法的输入,更好地应对水流、风力等外界干扰,输出水面无人艇航速与舵角控制量;依据总扰动力矩,得到无人艇的等效舵角值,与舵角控制量相加,得到最终的舵角控制信号,完成水面无人艇模糊建模,提高航行的安全性和可靠性。实验证明:该方法可有效确定水面无人艇的总扰动力矩,完成无人艇航速与舵角控制。

黑龙江地球物理站网数据干扰因素分析

基于黑龙江地球物理站网2018—2023年数据跟踪分析结果,统计并分析观测系统故障、自然环境干扰、场地环境干扰、人为干扰和地球物理事件对该站网的影响,总结并梳理常见干扰曲线形态特征,以发现制约站网运行的主要因素,明晰该站网监测效能,为数据分析与应用水平提升,以及仪器升级改造和观测环境改造提供参考。

地震流体观测井防止积水倒灌装置的研究与应用

一些地震流体观测井受周边观测环境的影响,容易在汛期出现降雨积水干扰现象,严重影响观测数据质量,甚至造成数据传感器故障。本文针对天津市滨海地震监测中心站民园井在观测中出现的积水倒灌现象,设计两种可根据观测井孔实际情况“量身定制”的用于防止观测井在降雨积水时出现倒灌的连通装置,并将观测井的最大水位深度、井口形状、周围空间环境和可能出现的最大积水深度等因素与装置规格建立理论转换关系式。实际应用情况表明,该装置可有效保护流体观测设备,减少观测数据干扰,提高观测数据的连续率和完整率,同时具备很强的适应能力,易于在流体观测井中推广,以解决低洼地区或洪水高发地区观测井的积水倒灌问题,为地震预测预报工作提供连续、完整的观测数据。

互感器检定装置整体检定技术综述

文章提出了一种互感器检定装置整体检定技术,从二次回路状态评估、电源校验技术、环境电磁干扰试验3个方面展开说明。该技术克服了传统单独检验部件的局限性,实现了测量用互感器检定装置整体性能的有效评估,在国内企业的推广应用中显著提高了产品质量,为电力系统的安全稳定经济运行提供了有力保障。

Electromagnetic environments in roadways of underground coal mines and a novel testing method

The electromagnetic environment of laneways in underground coal mines is an important area for the design of new electronic products,as well as a fundamental space for mine monitoring,surveillance,communications and control systems.An investigation of electromagnetic interference in coal mines is essential for the enhancement of performances of these systems.In this study,a new field method is provided in which radiated emission tests in coal mine laneways have been carried out.We conclude that:1) the wiring motor vehicles can radiate interference with a bandwidth up to 1 GHz and with an amplitude 10 dBμV/m higher than the background noise;2) the PHS(Personal Handy phone System) mobile communication system can cause interference 40 dBμV/m higher than the background noise;3) an interference 25 dBμV/m higher than the background noise can be generated during the communication at a working bandwidth of 48.8 MHz;and 4) power cables,battery vehicles as well as mechanical and electrical dong rooms have little effect on the electromagnetic radiation environment in coal mine tunnels.

An iterative interference cancellation based frequency offset estimation method for OFDMA uplink systems

In this paper, Moose scheme is used for frequency offset estimation in OFDMA uplink svstems due to that the signals from different users can be easily distinguished in frequency domain. However, differential multiple access interference （MAI） will deteriorate the frequency offset estimation performances, especially in interleaved OFDMA system. Analysis and simulation results manifest that frequency offset estimation by Moose scheme in block OFDMA system is more robust than that in interleaved OFDMA systern. And an iterative interference cancellation method has been proposed to suppress the differential MAI interference for interleaved OFDMA system, in which Moose scheme is the special case of the number of iteration is equal to one. Simulation results demonstrate that the proposed method can improve the performance with the increase of the number of iterations. In consideration of the performance and complexity, the proposed method with two iterations is selected. And the full comparison results of the proposed iterative method with two iterations and that with one iteration （conventional Moose scheme） are given in the paper, which sufficiently demonstrate that the performance gain can be obtained by the interference cancellation operation in interleaved OFDMA system.

Construction and Development of Green Livable Villages and Towns under Low-interference Cycle Strategy

Rural revitalization has multiple strategic significance,including improving the capacity of circular development of villages and towns,meeting the basic material needs of the rural population accounting for more than 50% of China’s total population,feeding the urban demand back,and building the rural ecological environment to make it green and livable,worthy of attention both inside and outside the society.This paper summarized the low-interference cycle strategy of green livable villages and towns by analyzing the spatial composition of villages and towns and the mechanism of circulation among various elements,forming a set of design strategies,which reduces adverse human interference on the ecology and improves the self-sustaining ability of villages and towns.This paper provides relevant reference suggestions for the construction of green livable villages and towns.

地电阻率观测常见变化形态及其可能原因分析

地电阻率连续观测中常见的变化形态有长趋势变化、年变、日变化、阶跃、高频扰动、快速下降/上升、年尺度持续性下降/上升变化等形态,且多种形态通常相互叠加在一起,构成观测曲线复杂的变化形态.本文结合地电阻率观测基本原理、地电学科多年的研究成果和异常核实工作,尝试对地电阻率观测中常见变化形态可能的产生原因进行分析和总结,以期为异常分析和震情跟踪提供一定的参考.

基于滑动窗口和置信度的无线传感器网络异常检测算法

针对无线传感器网络中异常检测误报率高及节点间通信开销大的问题,提出了基于滑动窗口和置信度的无线传感器网络异常检测算法(ADABSWC)。该算法使用环境干扰因子量化监测环境中的不确定性,建立异常数据干扰区间识别滑动窗口中的异常数据。提出了数据异常度的计算方法,用来预判异常来源;然后引入多通信半径划分最佳邻域,利用相对熵计算节点信息置信度;根据节点信息置信度协同判定出节点异常数据的来源。通过仿真实验,ADABSWC算法在不同传感器节点规模下均体现了较好的性能。该算法与KNN-PSOELM、OFN算法相比,事件节点、错误节点的检测率均高于98%,且误报率均低于1.5%。实验结果表明,所提出的算法可保证高检测精度的同时控制误报率在较低水平,算法拥有较好的容错性能。

铁路轨道现场测量准确性提升方法及测量数据应用思路

通过对现场测量过程的分析以及温度对轨距和超高测量结果的影响试验,得出影响现场测量结果准确性的主要因素有测量现场复杂环境、测量仪器的准确度、测量人员操作不规范、测量仪器选择错误等。可通过选用经过专业计量实验室校准或者检定的测量仪器、对测量结果进行修正、优化测量仪器的设计、选择适宜的测量时段等,减小测量仪器和环境因素对测量结果的不利影响;通过提高测量人员技术水平、规范测量过程等方法,消除人为因素导致的测量误差。采用大数据技术对测量数据间的关联及变化规律进行分析,进而预测线路未来状态,有利于实现线路维修从周期修转变到状态修。

基于自适应多重线性卡尔曼陷波的互调干扰抑制

针对环境中复杂多变的电磁辐射所引起的互调干扰问题,提出了一种基于自适应多重线性卡尔曼陷波(Adaptive Multiple Linear Kalman Notch Filter,AMLKNF)的互调干扰抑制方法.利用电磁环境效应试验建立的二阶互调低频阻塞干扰预测模型,在AMLKNF中设计一个自适应逻辑,根据干扰预测模型来调整陷波频率和深度,以抑制二阶互调低频阻塞干扰.最后通过仿真分析了该方法的性能,与传统陷波滤波方法相比,AMLKNF使信号损耗降低了30%以上,响应时间减少了1 ms,证明了该方法可以抑制至少40 dB的二阶互调低频阻塞干扰.

内置数据采集系统设计开发

针对工业现场数据集中采集的局限性,开发出一套分布式的内置数据采集系统。系统模块坚固小巧,抗电磁干扰能力强,采用导冷、防水的外壳设计,提高了系统的环境适应性,不同功能的模块能进行堆叠扩展,模块的功能能够进行重置,多系统能组成网络。系统可以方便地安装在设备狭隘的内部空间或者最大限度地靠近测量对象,满足了就地进行数据采集的要求,通过数字信号将数据传至数据中心,减少了模拟信号长距离传输的干扰,提高了数据采集精度。

三种地电阻率观测方式对比分析

基于青海门源Ms6.9地震,对比了该地震台三种地电阻率观测方式(地面常规、深井水平向、分层方案)的映震指标。结果表明,分层方案的映震指标更高。分层方案具有三个突出的特点:(1)与深井地电阻率水平向观测相比能够提高映震指标;(2)在指标的前提下解决了干扰问题(包括电磁干扰和季节性年变干扰);(3)获取的前兆异常形态更清晰、参数更明确(包括异常初始、异常时段、异常变幅、常态变幅和映震指标P1等5项参数)。尤其是它能够提高映震指标的事实,对地震前兆的监测有着实质性的帮助,解决了深井地电阻率观测中环境干扰的倾向性问题。

双酚A的内分泌干扰效应研究进展

双酚A(Bisphenol A,BPA)是一种危害生物体内分泌干扰效应的环境激素。近年来,随着工农业的不断发展,造纸行业、电子产品、食品包装等行业大量使用BPA,国内外主要河流、湖泊都不同程度受到了BPA的污染。BPA通过富集会影响人类激素的合成、释放、转运,进而影响人的生殖和发育。BPA的毒性效应主要包括内分泌干扰物、神经毒素、免疫毒素等方面,这些致毒效应甚至会增加细胞癌变、畸变的可能性。此外BPA毒性替代物、BPA与其他物质结合的产物都增加了BPA毒性的多样性,逐渐成为了危害人类生命安全的又一大隐患。通过研究BPA毒性效应以及近年来BPA的替代品,了解双酚A的致毒机理,为研究预防控制BPA污染对人类健康的影响提供参考依据。