Assimilation of temporal-spatial leaf area index into the CERES-Wheat model with ensemble Kalman filter and uncertainty assessment for improving winter wheat yield estimation

To accurately estimate winter wheat yields and analyze the uncertainty in crop model data assimilations, winter wheat yield estimates were obtained by assimilating measured or remotely sensed leaf area index （LAI） values. The performances of the calibrated crop environment resource synthesis for wheat （CERES-Wheat） model for two different assimilation scenarios were compared by employing ensemble Kalman filter （EnKF）-based strategies. The uncertainty factors of the crop model data assimilation was analyzed by considering the observation errors, assimilation stages and temporal-spatial scales. Overalll the results indicated a better yield estimate performance when the EnKF-based strategy was used to comprehen- sively consider several factors in the initial conditions and observations. When using this strategy, an adjusted coefficients of determination （R2） of 0.84, a root mean square error （RMSE） of 323 kg ha-1, and a relative errors （RE） of 4.15% were obtained at the field plot scale and an R2 of 0.81, an RMSE of 362 kg ha-1, and an RE of 4.52% were obtained at the pixel scale of 30 mx30 m. With increasing observation errors, the accuracy of the yield estimates obviously decreased, but an acceptable estimate was observed when the observation errors were within 20%. Winter wheat yield estimates could be improved significantly by assimilating observations from the middle to the end of the crop growing seasons. With decreasing assimilation frequency and pixel resolution, the accuracy of the crop yield estimates decreased; however, the computation time decreased. It is important to consider reasonable temporal-spatial scales and assimilation stages to obtain tradeoffs between accuracy and computation time, especially in operational systems used for regional crop yield estimates.

Monotonic Digit Filter for Limited-Area Model

Numerical diffusion or filter are used in most numerical models in order to eliminate small-scale (near two-grid intervals in wavelength) waves, However, conventional diffusion or filter schemes introduce the noise, and indeed few people realized, by filters themselves. For instance, most filters are troubled when they are put to use on meteorological fields with sharp gradient or with steep slope and consequently, the recurrence of undesirable numerical high-frequent oscillations (overshooting and undershooting) seems to be inevitable, Particularly when diffusion or filter is implemented in limited-area models, serious side effects on the limited-area boundaries often contaminate the modeling results. The merits and demerits are surveyed for commonly used diffusion or filter operations. A new type of monotonic digit filter is suggested to prevent overshooting and undershooting (due to the computational shock and Gibbs oscillation) nearby the discontinuous or nearly discontinuous locations when the filtering process was carried out, meanwhile the high selective property of damping is retained. Moreover, the new filter is designed on the implicit framework so that it can easily handle the problem of boundary diminishing in limited-area modeling.

残膜回收机有效作业面积监测系统设计研究

为便于新疆棉田残膜回收的精准作业收费和补贴,设计了一种残膜回收机有效作业面积监测系统。通过仿真试验对比锁相放大器降噪前后残膜回收机作业时经纬度数据,得出锁相滤波对于噪声环境有较好的抗干扰性能;采用高斯投影正算方法将降噪后经纬度数据转化为平面坐标,得出1.5°带的高斯投影的相对误差相较于3°带降低了0.01%。同时,利用卡尔曼滤波算法和构成角方法筛选有效作业轨迹,使用缓冲区法计算重复作业面积,最终利用轨迹算法精准获取残膜回收机有效作业面积,得出所设计的残膜回收机有效作业面积监测系统对于大块农田测量时相对误差为2.6%,对于小块农田测量时相对误差为3.3%。研究结果表明:所设计的残膜回收机有效作业面积监测系统可以精确计算出残膜回收机的有效作业面积,为残膜回收机作业质量评估提供了一定的理论基础。

气候变化对黄淮海地区粮食单产影响的HP滤波法分析

【目的】探究气候变化因素对黄淮海地区粮食单产长时间序列的波动性影响。【方法】基于1949—2021年黄淮海地区小麦和玉米的单产数据,采用HP滤波法进行单产分离,得到受技术进步和经济发展影响的长周期分量趋势单产,及受气候变化引起的短周期分量气候单产。【结果】对比实际单产数据,HP滤波分离得到的趋势单产与作物实际单产具有相似的年际变化特征,趋势单产变化更为平滑,波动幅度小于实际单产;气候单产年际波动幅度最大,其变化情况直接影响当年实际单产;气候单产对实际单产的影响分为正反两方面;不同作物同一年份受气候单产影响程度不同。【结论】尽管气候变化对农业生产影响很大,但是在长期层面来讲,小麦和玉米的单产主要受种植技术、作物品种改良、数智化技术等科学技术发展因素的影响。

Adaptive Robust Tracking Control of Pressure Trajectory Based on Kalman Filter

When adaptive robust control（ARC） strategy based on backstepping design is applied in pneumatic servo control, accurate pressure tracking in motion is especially necessary for both force and position trajectories tracking ofrodless pneumatic cylinders, and therefore an adaptive robust pressure controller is developed in this paper to improve the tracking accuracy of pressure trajectory in the chamber when the pneumatic cylinder is moving. In the proposed adaptive robust pressure controller, off-line fitting of the orifice area and on-line parameter estimation of the flow coefficient are utilized to have improved model compensation, and meanwhile robust feedback and Kalman filter are used to have strong robustness against uncertain nonlinearities, parameter fluctuations and noise. Research results demonstrate that the adaptive robust pressure controller could not only track various pressure trajectories accurately even when the pneumatic cylinder is moving, but also obtain very smooth control input, which indicates the effectiveness of adaptive model compensation. Especially when a step pressure trajectory is tracked under the condition of the movement of a rodless pneumatic cylinder, maximum tracking error of ARC is 4.46 kPa and average tracking error is 0.99 kPa, and steady-state error of ARC could achieve 0.84 kPa, which is very close to the measurement accuracy of pressure transducer.

Evaluation of Structural Patterns and Related Alteration and Mineralization Zones by Using ASAR-ASTER Imagery in Siyahrood Area (East Azarbaijan—NW Iran)

The NW part of Iran belongs to the Iranian plateau that is a tectonically active region within the Alpine-Himalayan orogenic belt. The intrusion of Oligocene parts in various faces caused the alteration and mineralization such as copper, molybdenum, gold and iron in the Siyahrood area. Granitoidic rocks with component of Granodiorite to alkali have been influenced by hydrothermal fluids. Alteration zones are important features for the exploration of deposits and the ASTER sensor is able to identify the type of alteration and its alteration zoning. This method can be a useful tool for detecting potential mineralization area in East Azarbaijan—Northwest of Iran. The purpose of this study is to evaluate ASTER data for mapping altered minerals in Siyahrood area in order to detect the potential mineralized areas. In this study, false color composite, and band ratio techniques were applied on ASTER data and argillic, phyllic, Iron oxide and propylitic alteration zones were separated. ASAR image processing has been used for lineaments and faults identified by the aid of directional filter. The structural study focused on fracture zones and their characteristics including strike, length, and relationship with alteration zones. The results of this study demonstrate the usefulness of remote sensing methods and ASTER multi-spectral data for alteration, and ASAR data are useful for lineament mapping.

Assimilation of Remote Sensing and Crop Model for LAI Estimation Based on Ensemble Kalman Filter

Data assimilation in agricultural remote sensing research is of great significance to integrate with remote sensing observations and model simulations for parameters estimation. The present investigation not only designed and realized the Ensemble Kalman Filtering algorithm （EnKF） assimilation by combing the crop growth model （CERES-Wheat） with remote sensing data, but also optimized and updated the key parameters （LAI） of winter wheat by using remote sensing data. Results showed that the assimilation LAI and the observation ones agreed with each other, and the R2 reached 0.8315. So assimilation remote sensing and crop model could provide reference data for the agricultural production.

Novel adaptive Hatch filter to mitigate the effects of ionosphere and multipath on LAAS

It has been proven that carrier smoothing and differential global positioning system （DGPS） are effective to improve the accuracy of pseudorange by reducing the noise in it and eliminating almost all the common mode errors between the ground station and user. However, another issue coming with local area augmentation system （LAAS） is how to find an adaptive smoothing window width to minimize the error on account of ionosphere delay and multipath. Based on the errors analysis in carrier smoothing process, a novel algorithm is formulated to design adaptive Hatch filter whose smoothing window width flexibly varies with the characteristic of ionosphere delay and multipath in the differential carrier smoothing process. By conducting the simulation in LAAS and after compared with traditional Hatch filers, it reveals that not only the accuracy of differential correction, but also the accuracy and the robustness of positioning results are significantly improved by using the designed adaptive Hatch filter.

湖北漳河灌区中稻气象产量变化特征及预测模型

准确的气象产量是正确评估气象条件对粮食产量影响的前提。为了探究湖北漳河灌区单季稻气象产量的时间序列变化规律,尝试通过三点滑动平均法、HP滤波法和一次指数平滑法、二次指数平滑法4种方法将漳河灌区1975—2020年的水稻单产数据分离为水稻趋势产量及气象产量,通过相关分析筛选水稻8个生育阶段的主要气象因子,然后与分离的气象产量构建水稻预测模型。结果表明:4种分割方法均能较好地反映气象产量序列与湖北省生产力发展水平的区域一致性特点,多年平均气象产量占总产量的比例约为3.39%,但2008年以后其占比达到10.1%。相关分析识别出抽穗开花期最低气温、拔节孕穗期最高气温、分蘖后期平均气温、返青期最低气温、乳熟期蒸发量和育苗最低气温是影响气象产量的主要因子,该模型在率定期(1976—2014年)和验证期(2015—2020年)的相对误差均在5%以内,模型的决定系数R 2为0.994。预测模型有助于研究未来气候变化下的区域水稻产量的变化。

Localization and mapping in urban area based on 3D point cloud of autonomous vehicles

In order to meet the application requirements of autonomous vehicles, this paper proposes a simultaneous localization and mapping （SLAM） algorithm, which uses a VoxelGrid filter to down sample the point cloud data, with the combination of iterative closest points （ICP） algorithm and Gaussian model for particles updating, the matching between the local map and the global map to quantify particles＇ importance weight. The crude estimation by using ICP algorithm can find the high probability area of autonomous vehicles＇ poses, which would decrease particle numbers, increase algorithm speed and restrain particles＇ impoverishment. The calculation of particles＇ importance weight based on matching of attribute between grid maps is simple and practicable. Experiments carried out with the autonomous vehicle platform validate the effectiveness of our approaches.

林区机载LiDAR点云的多分辨率层次布料模拟滤波

针对现有机载LiDAR(light detection and ranging)点云滤波方法在地形起伏剧烈的林区适用性不足的问题,提出一种多分辨率层次布料模拟滤波方法。首先,通过多尺度形态学开运算选择大量种子地面点;然后,基于种子地面点,使用布料模拟法由低至高逐层构建参考地形,以快速获取高分辨率参考地形;最后,基于点至参考地形的高差区分地面点和非地面点。利用国际摄影测量和遥感学会提供的数据集和参考方法,评估该方法性能。利用在中国、美国多个代表性林区的点云数据,评估该方法的可推广性。结果表明,该方法的Kappa系数和运行时间是83.72%和34.11 s,精度和效率较经典布料模拟滤波方法提高10.49%和52.17%。相比8种参考方法,该方法能够获得更高精度,并且具有稳定的可推广性。

卷烟滤棒成型加工区域集控系统实现

针对滤棒成型作业区分散、设备种类多、制造厂家和数量多、接口协议复杂且不统一以及海量数据变量难识别等问题,设计并开发了基于OPC UA架构和实时内存数据库的就地滤棒加工区数采和监控系统。自主开发OPC服务器,实现了滤棒成型主、辅设备的实时数据采集,并通过高效内存数据库服务器对生产及设备信息进行海量存储,进而实现了对滤棒成型车间生产过程信息的全面、准确迁移集成,以及对滤棒生产、产量、质量、机台效率、设备状态等信息的可视化区域集控。

融合色彩增强与投影展平的蚕茧疵点面积计算方法

在蚕茧分级过程中,常以疵点面积作为评价指标。为计算存在颜色缺陷的蚕茧的表面疵点面积,文中提出了一种融合色彩增强与投影展平的蚕茧疵点面积计算方法。首先,对亮度增强后的原始图像V通道进行阈值分割及矩形拟合,获取图像ROI(region of interest)区域;然后,在带颜色恢复的多尺度Retinex(multi-scale Retinex with chromaticity preservation,MSRCP)算法中添加完美反射白平衡算法,配合多尺度快速引导滤波器,提高疵点区域的对比度;最后,通过投影展平将投影面积转化为实际曲面面积。实验结果表明,文中算法计算所得面积与人工测量面积的误差范围在3.8%~8.7%,最大误差面积为0.07 cm^(2),满足次下茧分级的精度要求。

自适应正则化滤波化极方法研究

化极是消除磁力异常斜磁化影响的关键步骤,可以在波数域(频率域)和空间域中实现.相比于空间域,在波数域(频率域)进行化极简单且高效,但在低纬度地区存在不稳定性问题,因此明确低纬度地区的范围,研究稳定、实用、精度高的低纬度地区化极方法具有重要意义.本文通过理论研究得出化极因子振幅的最大值为2时,对应的磁化倾角的值为±45°,当磁化倾角在该范围内时,引起化极不稳定.因此采用正则化思想,提出了自适应正则化滤波化极方法(ARF-RTP),该方法利用化极因子振幅构建正则化滤波函数,并以振幅值等于2作为约束计算化极方法的参数值,从而实现自适应化极处理,提高了化极方法的稳定性及实用性.同时结合迭代算法提高了此方法的精度,有效地解决了低纬度地区化极的不稳定性问题.自适应正则化滤波这一思想不但可以解决化极的不稳定性问题,而且可以解决分量转换或者磁化方向转换的不稳定性问题以及类似数据处理中的不稳定性问题,具有广阔的推广应用前景.

一种高性能、小面积的Sigma Delta DAC数字电路设计

该文设计一种高性能、小面积的Sigma Delta DAC,其中包括插值滤波器和数字调制器。插值滤波器由两级半带滤波器和CIC滤波器级联组成,实现128倍插值。在两级半带滤波器硬件实现中,滤波器系数采用查找表实现,滤波运算数据采用SRAM存储,并通过乘法器的时分复用实现,大大减少对硬件资源的使用。数字调制器采用量化误差反馈型的多bit量化Mash 1-1-1结构,这种结构不需要复杂的乘法运算,简化设计并提高系统的可靠性。该DAC数字电路在90 nm CMOS工艺下实现,面积为0.0535 mm^(2),功耗为1.0103 mW。经过测试,数字调制器输出的带内信噪比为132.2 dB,有效位数21.67,可以满足小面积、高性能DAC的设计需求。

高脂血症型胰腺炎患者内脏脂肪组织面积与双重滤过血浆置换临床疗效的相关性分析

目的探讨高脂血症型胰腺炎(hyperlipidemic pancreatitis,HLAP)患者内脏脂肪组织面积(visceral fat area,VFA)与双重滤过血浆置换(double filtered plasmapheresis,DFPP)临床疗效的相关性。方法选取2020年1月—2022年12月自贡市第一人民医院收治的行DFPP治疗的HLAP患者,根据临床疗效不同分为有效组和无效组。比较2组的一般资料及VFA;通过多元Logistic回归分析无效结局的影响因素;分析VFA水平与疗效无效概率的剂量反应关系,基于影响因素逐步Logistic回归模型。结果共纳入225例患者,其中有效组180例,无效组45例。饮酒史(OR=3.603,95%CI:2.577~4.868,P=0.018)、高体质量指数(body mass index,BMI)(OR=2.407,95%CI:1.381~3.672,P=0.016)、高急性生理学与慢性健康状况评分系统Ⅱ(acute physiology and chronic health status scoring system II,APACHEⅡ)评分(OR=3.087,95%CI:2.061~4.352,P=0.026)、高空腹血糖(FPG)(OR=1.313,95%CI:1.007~2.578,P=0.009)、高总胆固醇(TC)(OR=2.511,95%CI:1.485~3.776,P=0.025)、高三酰甘油(TG)(OR=4.885,95%CI:3.859~6.150,P=0.035)、高低密度脂蛋白胆固醇(LDL-C)(OR=3.165,95%CI:2.139~4.430,P=0.010)、低高密度脂蛋白胆固醇(HDL-C)(OR=4.163,95%CI:3.137~5.428,P=0.011)、高白细胞介素-6(interleukin-6,IL-6)(OR=2.117,95%CI:1.091~3.382,P=0.006)、高白细胞介素-8(interleukin-8,IL-8)(OR=3.115,95%CI:2.089~4.380,P=0.023)、高C反应蛋白(CRP)(OR=1.975,95%CI:1.049~3.240,P=0.035)、高降钙素原(procalcitonin,PCT)(OR=3.665,95%CI:2.639~4.930,P=0.036)、高血淀粉酶(OR=4.547,95%CI:3.521~5.812,P=0.041)、高血脂肪酶(OR=2.229,95%CI:1.203~3.494,P=0.043)、VFA大(OR=2.827,95%CI:1.801~4.092,P=0.031)是疗效无效的影响因素。剂量反应关系分析提示:随着VFA增加,临床疗效无效的发生概率也相应增加。回归方程P=1/[1+exp(-3.265+1.282×饮酒史+0.878×BMI+1.127×APACHEⅡ评分+0.272×FPG+0.921×TC+1.586×TG+1.152×LDLC+1.426×HDL-C+0.750×IL-6+1.136×IL-8+0.681×CRP+1.299×PCT+1.514×血淀粉酶+0.802×血脂肪酶+1.039×VFA)]。结论HLAP患者VFA与DFPP临床疗效具有显著相关性。随着VFA的增加,临床疗效无效的发生概率逐渐升高。

基于时空连续补偿的矿山可通行区域识别方法

可通行区域识别是矿山无人驾驶技术中的重要环节。露天矿山道路场景具有道路边界模糊不清及路面平坦度不一等特征,使用传统同心圆地面分割模型进行矿山道路平面拟合时容易出现可通行区域与车辆不连通及帧间可通行区域识别结果不一致等误分类问题。提出了一种基于时空连续补偿的矿山道路可通行区域识别方法。首先,基于同心圆模型对矿山道路建模,并利用主成分分析方法进行多平面拟合,获取初始可通行区域分割结果;然后,基于空间连通性,分别利用区域生长方法和基于密度的噪声应用空间聚类方法对初始可通行区域进行区域连通性滤波及点连通性滤波,得到符合空间连通性的可通行区域;最后,基于时间区域一致性对不同点云帧中可通行性不一致的不稳定区域进行滤除,先根据正态分布变换方法构建栅格地图,再利用时间稳定权重判断栅格稳定性,最终通过区域栅格投影实现不稳定区域的滤除。矿山场景中测试结果表明:该方法的准确率为93.44%,较现有主流方法提升2.27%;召回率为99.14%,较现有主流方法提升8.26%。该方法不仅在不连通区域中具有良好的空间连通性,还在崎岖区域内具有良好的时序稳定性。

甲醇制烯烃装置水洗水泵振动超标原因分析与治理

针对甲醇制烯烃装置水洗水泵试车过程中振动超标的问题进行了分析,通过消除泵基座灌浆缺陷、复测泵联轴器对中、检查管道支撑及连接应力、调整改造过滤器等一系列措施,逐步排查分析泵振动的影响因素。根据泵入口过滤器的安装情况及结构参数,定量计算有效过滤面积,结合测试数据分析,发现过滤器有效过滤面积不足是影响泵吸入流量、导致泵振动超标的重要因素。通过对过滤器滤筒进行改造,降低流体阻力、偏流、涡流的影响,提高流体通量,大大改善了泵的振动状态。

利用ArcPy裁切含重叠区域多源影像的方法探讨

为了提升遥感影像数据的处理能力,本文基于日常遥感影像处理的裁切需求,设计程序自动提取多源影像的真实边界、时相和分辨率信息,并按照时相优先或分辨率优先的原则,筛选不规则多边形范围内的重叠区影像,将多个不同影像源的影像块进行规则组合和镶嵌,从而得到新影像。该方法可作为Erdas和ArcGIS影像裁切功能的补充,能节约大量时间和人工成本,提升工作效率。

遥感航测技术在地图测绘中的应用探讨

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