组合粗差探测的MHSS ARAIM算法

针对目前MHSS ARAIM (multiple hypothesis solution separation advanced receiver autonomous integrity monitoring)算法存在的抗差能力弱、计算子集过多、计算量过大等不足,提出一种组合粗差探测的MHSS ARAIM算法。该算法先用粗差探测方法对原始数据进行粗差识别与剔除,而后用MHSS ARAIM算法处理经粗差探测后的数据,可弥补MHSS ARAIM算法的不足。对若干IGS和全球连续监测评估系统iGMAS(international GNSS monitoring and assessment system)监测站观测数据进行计算和分析。结果表明:在航行LPV-200阶段,该算法应用于GPS和BDS导航的性能优于MHSS ARAIM;在假设单故障情况下,该算法对GPS和BDS观测数据的有效监视门限EMT(effective monitor threshold)的精度分别提高了22.47%和9.63%,对VPL(vertical protection level)的精度分别提高了32.28%和12.98%;在假设双故障情况下,对EMT的精度分别提高了80.85%和29.88%,对VPL的精度分别提高了49.66%和18.24%。     

一例异育银鲫(Carassius auratus gibelio)暴发性出血病病原分析

2016年6月,江苏某异育银鲫(Carassius auratus gibelio)养殖场暴发一种传染性急性出血病,造成养殖银鲫大量死亡。为分析此次疾病病因及流行规律,本研究从发病养殖场采集患出血病的异育银鲫,从细菌、病毒及寄生虫三个方面对病原进行了分析。采用病原菌分离、组织病理学观察、超薄切片电镜观察、病毒核酸分析、回感实验等对病原进行鉴定。结果显示从发病鲫鱼体内分离到病毒一株,未发现寄生虫及细菌感染。经测序及序列分析,该病毒为鲤疱疹病毒Ⅱ型(Cyprinid herpesvirus2,CyHV-2)病毒,组织病理学观察结果显示患病鱼的鳃和肾脏有明显病变,电镜下可观察到病鱼脾脏组织有带囊膜的球形病毒,囊膜直径约为170—200nm,病毒衣壳直径约为110—120nm,核心直径约为60nm,用组织匀浆感染鲫鱼囊胚细胞系(CGB)可稳定地观察到典型的细胞病变,用患病鱼组织匀浆液人工感染异育银鲫的死亡率高达100%,荧光定量PCR检测到该病毒可感染多器官,其中以脾脏中病毒含量最高,其次是脑,肝脏中最少。本研究可为CyHV-2的诊断防控及疫苗研制提供资料。     

经济海藻病害及防控技术的研究进展

经济海藻的病害一直是海藻人工栽培的一大障碍,往往造成严重的经济损失。目前对藻类病害的研究大多集中于病原鉴定,而病原的多样性和复杂的海区微环境增加了病原分离和鉴定的难度。本文综述了经济海藻病害发生的原因、病原的多样性和致病机制、病原的鉴定、检测和防治方法,并对未来我国海藻病害研究方向进行了展望,以期对藻类病害的防控提供参考。     

基于GF-3的不同极化方式SAR图像海面油膜识别的比较 ——以"桑吉"轮事故为例

基于我国自主研发的首颗分辨率达到1m的C频段多极化合成孔径雷达高分三号卫星(GF-3),通过典型溢油案例定性和定量地比较了双极化与单极化图像预处理性能,分析了不同的极化组合对海面油膜识别结果的影响。得出结论:同向极化与异向极化成像差异明显,VV极化明显比VH极化回波强度高,并且油膜识别度较高;相反,双极化VHVV方式与单极化VH方式图像效果区别不大,双极化方式并不能绝对性地提高地物识别度。     

柳珊瑚Leptogorgia rigida中甾体类成分研究

首次对南海柳珊瑚Leptogorgia rigida中甾体类次生代谢产物进行研究。采用硅胶柱柱层析、十八烷基硅烷键合硅胶填料、Sephadex LH-20、高效液相色谱(HPLC)及薄层色谱(TLC)等多种方法进行分离纯化, 通过核磁共振波谱(NMR)、质谱(MS)等现代波谱分析及物理常数对照等方法进行结构鉴定。从南海柳珊瑚Leptogorgia rigida次生代谢产物中分离得到8个甾类化合物, 结构依次为: 3β, 6β, 11-trihydroxy-9, 11-seco-5α-chloest-7-en-9-one (1); 3β, 6α, 11- trihydroxy-9, 11-seco-5α-chloest-7-en-9-one (2); 3β, 6α, 11-trihydroxy-5α-chloest-7, 22(E)-dien-9-one (3); pregnan-4-en-3, 20-dione (4); 5α-pregnan-3, 20-dione (5); 3β-hydroxy-pregnan-5-en-20-dion (6); 3β-hydroxy-5α-pregnan-20-one (7); 和3β, 6α, 11-trihydroxy-9, 11-seco-5α-gorgosterol (8)。所有化合物均首次从Leptogorgia属中得到。     

基于时间序列叶面积指数稀疏表示的作物种植区域提取

以华北平原黄河以北地区为研究区域,以时间序列叶面积指数LAI(Leaf Area Index)傅里叶变换的谐波特征作为不同作物识别的数据源,利用稀疏表示的分类方法识别2007年—2016年冬小麦、春玉米、夏玉米等主要农作物种植区域。首先利用上包络线Savitzky-Golay滤波分别对2007年—2016年的时间序列MODIS LAI曲线进行重构,进而对重构的年时间序列LAI进行傅里叶变换,以0—5级谐波振幅、1—5级谐波相位作为作物识别的依据,基于各类地物的训练样本,通过在线字典学习算法构建稀疏表示方法的判别字典,对每个待测样本利用正交匹配追踪算法求解稀疏系数,从而计算对应于各类地物的重构误差,根据最小重构误差判定待测样本的作物类型,并对作物识别结果的位置精度进行验证。结果表明,2007年—2016年作物识别的总体精度为77.97%,Kappa系数为0.74,表明本文提出的方法可以用于研究区域主要作物种植区域的提取。     

和田玉的鉴定与评估

新疆和田玉是世界软玉品种中最好的一种,有“玉王”之称。该文对和田玉的矿物组成、化学成分及物理性质进行了鉴定分析,提出了和田玉原料及玉器的评估方法。     

迟缓爱德华氏菌致病相关因子的研究进展

迟缓爱德华氏菌(Edwardsiealla tarda)是引起多种鱼类产生爱德华氏菌病(edwardsiellosis)的病原菌。随着水产养殖业的日益发展,致病性迟缓爱德华氏菌对水产养殖业的危害也越来越严重。有关迟缓爱德华氏菌的致病机理至今还没有系统、清晰的阐释,但近些年对其致病相关因子的研究已逐渐深入。文中对迟缓爱德华氏菌的生物分型、快速检测技术等进行了简要阐述,并对该病原菌的主要致病相关因子,包括黏附因子、抵抗宿主免疫机制的酶类、各种毒素、Ⅲ型和Ⅵ型分泌系统、载铁体及磷酸盐特异转运操纵子进行了详细阐述,以期为迟缓爱德华氏菌致病机理的进一步深入研究及其防治提供参考和借鉴。     

Vision-based tracking with projective mapping for parameter identification of remotely operated vehicles

Parameter identification of a remotely operated vehicle (ROV) is often based on the dynamic responses collected by its onboard sensors. However, for commercial ROVs, the required data for identification may not be available due to the absence of suitable sensors or limitations in accessing onboard sensor data. Therefore, this study proposes a vision-based tracking system to measure the dynamic response of an ROV. The tracking system is independent of the ROV, and is able to localize an ROV to a high degree of precision by means of projective mapping. The validity of the proposed tracking system is demonstrated through identification of a commercial ROV. A simplified nonlinear ROV dynamic model with six degrees of freedom (DOF) is used for identification. Uncoupled motions, including surge, sway, and yaw, are obtained from the ROV dynamic model, and the corresponding experiments are carried out for each DOF. Hydrodynamic parameters are then estimated with numerical optimizations by comparing the measured ROV responses with the output of the mathematical model. The experimental results show that the vision-based tracking system can accurately measure the transient and steady-state responses of an ROV. Additionally, the simulations of the ROV dynamic model, with the optimal parameter estimates, give results in agreement with the measured data.     

System identification for nonlinear maneuvering of large tankers using artificial neural network

This paper deals with the application of nonparametric system identification to a nonlinear maneuvering model for large tankers using artificial neural network method. The three coupled maneuvering equations in this model for large tankers contain linear and nonlinear terms and instead of attempting to determine the parameters (i.e. hydrodynamic derivatives) associated with nonlinear terms, all nonlinear terms are clubbed together to form one unknown time function per equation which are sought to be represented by the neural network coefficients. The time series used in training the network are obtained from simulated data of zigzag maneuvers and the proposed method has been applied to these data. The neural network scheme adopted in this work has one middle or hidden layer of neurons and it employs the Levenberg–Marquardt algorithm. Using the best choices for the number of hidden layer neurons, length of training data, convergence tolerance etc., the performance of the proposed neural network model has been investigated and conclusions drawn.