基于地表温度和植被指数的黑龙江省旱情遥感动态监测

干旱灾害是一种影响范围广、时间跨度大的自然灾害,对社会经济发展尤其是给农业生产造成重大损失。遥感技术具有观测空间尺度大、实时性强的特点,有利于大范围、实时、动态的旱情监测。利用MODIS的LST和NDVI遥感数据,依托站点实测土壤含水率数据,分析土壤含水率与地表温度和植被指数之间的关系,考虑土壤类型,构建温度植被多项式模型,进行表层土壤水分反演,基于此开展2018年3~7月黑龙江省旱情遥感监测应用研究。监测结果显示,监测期内黑龙江省经历了两次规模较大的干旱过程,干旱的核心区域为黑龙江省西南部区域,与实际情况相吻合。研究表明,考虑土壤类型的温度植被多项式模型对旱情遥感监测具有良好的应用效果。     

Colorectal Laterally Spreading Tumors by Computed Tomographic Colonography

To date, few reports focused primarily on detecting colorectal laterally spreading tumors (LSTs) have been published. The aim of this study was to determine the visibility of LSTs on computed tomographic colonography (CTC) compared with that on colonoscopy as a standard. We retrospectively reviewed and matched data on endoscopic and CTC reports in 157 patients (161 LSTs) who received a multidetector CT scan using contrast media immediately after total colonoscopy at the National Cancer Center Hospital in Tokyo, Japan, between December 2005 and August 2010. The results of the total colonoscopy were known at the time of the CTC procedure and reading. Of the 161 LSTs detected on colonoscopy, 138 were observed and matched by CTC (86%). Of the 91 granular type LSTs (LST-Gs), 88 (97%) were observed and matched, while of the 70 non-granular type LSTs (LST-NGs), 50 (71%) were observed and matched by CTC (p < 0.0001). CTC enabled observation of 73% (22/30) of 20–29 mm, 83% (35/42) of 30–39 mm, 88% (49/56) of 40–59 mm, and 97% (32/33) of ≥60 mm tumors. The rate of observed LSTs by CTC was 86% (97% of LST-G, 71% of LST-NG) of the LSTs found during total colonoscopy.     

Analysis of shearing effect on tunnel induced by load transfer along longitudinal direction

In order to analyze the behavior of load transfer mechanism of shield-constructed tunnel in longitudinal direction, tunnel is modeled as the cylindrical shell within elastic foundation (CSEF). By applying the theory of elastic cylindrical shell (ECS) with considering shear deformation and assumed displacement functions of trigonometric series, the distribution of stress and deformation in tunnel lining is obtained. In the solution, the stiffness of tunnel lining is decomposed into two components of circumferential and radial stiffness. The effects of both components on the behavior of deformation and internal forces of tunnel lining are discussed in details. By using the proposed solution, more reasonable results on the behavior of tunnel lining are obtained, e.g bending moment in tunnel cross section becomes smaller with the increase of the circumferential shear stiffness. The analytical results are verified by the results of 3D FEM analysis and field measured data. In accordance with the proposed analytical method, the tunnel lining in soft ground should be designed via considering the following aspects: (i) three dimensional effect of tunnel lining; (ii) relatively weaker shear stiffness in radial direction, and (iii) increase the circumferential shear resistance between rings.     

琼东南盆地深水区储层分布规律

琼东南盆地深水区经历了断陷、断拗和拗陷3大构造演化和沉积充填阶段,主要发育4种沉积体系,相应地形成了4类主要储层:1)陵三段扇三角洲或滨海相砂岩储层;2)三亚、梅山组滨浅海相砂岩储层;3)三亚—莺黄组低位体储层;4)梅山组台地边缘礁滩灰岩储层。平面上,储层发育具有明显的分带性,可划分为:北部浅水陆架滨岸砂岩、三角洲砂岩储层发育带;中央坳陷低位体储层发育带;南部永乐隆起区碳酸盐岩储层发育带。深水区主要位于后2个带,每个带储层发育的控制因素不同,可以进一步划分为多个储层发育区。每个储层发育区存在多套储盖组合,每套储盖组合在多个储层区中发育。其中台地灰岩储层可能成为南部隆起区具有重要意义的勘探层系。      

分层空时码多载波CDMA的译码与检测

研究V－BLAST MIMO MC－CDMA下行系统。提出了一种对每个子载波进行V－BLAST译码的非线性 算法,对不同天线数、用户数情况进行了系统的仿真和分析,并对V－BLAST译码的线性和非线性算法进行了系 统仿真比较。     

Changes in land surface temperatures and NDVI values over Europe between 1982 and 1999

We used land surface temperature (LST) algorithms and NDVI values to estimate changes in vegetation in the European continent between 1982 and 1999 from the Pathfinder AVHRR Land (PAL) dataset. These two parameters are monitored through HANTS (Harmonic ANalysis of Time Series) software, which allows the simultaneous observation of mean value, first harmonic amplitude and phase behaviors in the same image. These results for each complete year of data show the effect of volcanic aerosols and orbital drift on PAL data. Comparison of time series of HANTS cloud-free time series with the original time series for various land cover proves that this software is useful for LST analysis, although primarily designed for NDVI applications. Comparison of yearly averages of HANTS LST over the whole Europe with air temperature confirms the validity of the results. Maps of the evolution for both parameters between periods 1982/1986 and 1995/1999 have been elaborated: NDVI data show the well confirmed trend of increase over Europe (up to 0.1 in NDVI), Southern Europe seeing a decrease in NDVI (− 0.02). LST averages stay stable or slightly decrease (up to − 1.5 K) over the whole continent, except for southern areas for which the increase is up to 2.5 K. These results evidence that arid and semi-arid areas of Southern Europe have become more arid, the rest of Europe seeing an increase in its wood land proportion, while seasonal amplitude in Northern Europe has decreased.     

MODIS数据反演地表温度的参数敏感性分析

在利用MODIS卫星遥感数据进行地表温度反演过程中，有两个基本参数需要确定，即地表比辐射率和大气透过率，尽管采用了比较合理的参数估计方法，但仍会有一些不可避免的因素导致误差的产生。为了进一步研究可能的参数误差对地表温度反演精度的影响，我们对该算法的两个参数进行敏感性分析。结果表明，当31、32两个波段的参数估计都有中等误差时，可能的地表温度误差对大气透过率和地表比辐射率都不敏感，所引起的地表温度误差大约为0．6～0．8℃，算法能够得到较高精度的地表温度反演结果。     

共享有限资源的有期限约束多工作流吞吐量最大化调度方法

为了进一步提高计算资源利用率,提出了工作流在分布式异构环境中的协同调度算法.首先,提出反向异构最早完成时间优先(heterogeneous earliest finish time,HEFH)调度策略,可以快速求出多个工作流中每个子任务的近似最晚开始时间和子期限,并基于最晚开始时间定义了当前任务相对宽松度的衡量指标,通过对比选出所有工作流中优先级最高的任务,在现有资源中寻找具有最早完成时间的时隙进行映射,并在资源不足时根据子期限及时判定出过饱和现象,合理丢弃用HEFT算法单独调度具有最小时隙的工作流,达到吞吐量最大化.结果表明:这种算法综合对比其他3种在吞吐量、浪费时隙率、公平度及时间复杂度方面有着较好性能.     

Testing a MODIS Global Disturbance Index across North America

Large-scale ecosystem disturbances (LSEDs) have major impacts on the global carbon cycle as large pulses of CO₂ and other trace gases from terrestrial biomass loss are emitted to the atmosphere during disturbance events. The high temporal and spatial variability of the atmospheric emissions combined with the lack of a proven methodology to monitor LSEDs at the global scale make the timing, location and extent of vegetation disturbance a significant uncertainty in understanding the global carbon cycle. The MODIS Global Disturbance Index (MGDI) algorithm is designed for large-scale, regular, disturbance mapping using Aqua/Moderate Resolution Imaging Spectroradiometer (MODIS) Land Surface Temperature (LST) and Aqua/MODIS Enhanced Vegetation Index (EVI) data. The MGDI uses annual maximum composite LST data to detect fundamental changes in land-surface energy partitioning, while avoiding the high natural variability associated with tracking LST at daily, weekly, or seasonal time frames. Here we apply the full Aqua/MODIS dataset through 2006 to the improved MGDI algorithm across the woody ecosystems of North America and test the algorithm by comparison with confirmed, historical wildfire events and the windfall areas of documented major hurricanes. The MGDI accurately detects the location and extent of wildfire throughout North America and detects high and moderate severity impacts in the windfall area of major hurricanes. We also find detections associated with clear-cut logging and land-clearing on the forest-agricultural interface. The MGDI indicates that 1.5% (195,580 km²) of the woody ecosystems within North America was disturbed in 2005 and 0.5% (67,451 km²) was disturbed in 2006. The interannual variability is supported by wildfire detections and official burned area statistics.     

Retrieving soil temperature profile by assimilating MODIS LST products with ensemble Kalman filter

Proper estimation of initial state variables and model parameters are vital importance for determining the accuracy of numerical model prediction. In this work, we develop a one-dimensional land data assimilation scheme based on ensemble Kalman filter and Common Land Model version 3.0 (CoLM). This scheme is used to improve the estimation of soil temperature profile. The leaf area index (LAI) is also updated dynamically by MODIS LAI production and the MODIS land surface temperature (LST) products are assimilated into CoLM. The scheme was tested and validated by observations from four automatic weather stations (BTS, DRS, MGS, and DGS) in Mongolian Reference Site of CEOP during the period of October 1, 2002 to September 30, 2003. Results indicate that data assimilation improves the estimation of soil temperature profile about 1 K. In comparison with simulation, the assimilation results of soil heat fluxes also have much improvement about 13 W m^− 2 at BTS and DGS and 2 W m^− 2 at DRS and MGS, respectively. In addition, assimilation of MODIS land products into land surface model is a practical and effective way to improve the estimation of land surface variables and fluxes.