ENVI FLAASH和ERDAS ATCOR2的大气校正对比研究

研究分别用ENVI FLAASH模块和ERDAS ATCOR2模块对LANDSAT5-TM图像进行大气校正,进而对校正效果进行评价。结果表明,ENVI FLAASH和ERDAS ATCOR2均能很好地消除大部分大气的影响,满足试验要求。但从精度方面考虑,ENVI FLAASH要略胜于ERDAS ATCOR2。     

Evaluation of options for increasing yield and water productivity of wheat in Punjab, India using the DSSAT-CSM-CERES-Wheat model

The DSSAT-CSM-CERES-Wheat V4.0 model was calibrated for yield and irrigation scheduling of wheat with 2004–2005 data and validated with 13 independent data sets from experiments conducted during 2002–2006 at the Punjab Agricultural University (PAU) farm, Ludhiana, and in a farmer's field near PAU at Phillaur, Punjab, India. Subsequently, the validated model was used to estimate long-term mean and variability of potential yield (Y_p), drainage, runoff, evapo-transpiration (ET), crop water productivity (CWP), and irrigation water productivity (IWP) of wheat cv. PBW343 using 36 years (1970–1971 to 2005–2006) of historical weather data from Ludhiana. Seven sowing dates in fortnightly intervals, ranging from early October to early January, and three irrigation scheduling methods [soil water deficit (SWD)-based, growth stage-based, and ET-based] were evaluated. For the SWD-based scheduling, irrigation management depth was set to 75 cm with irrigation scheduled when SWD reached 50% to replace 100% of the deficit. For growth stage-based scheduling, irrigation was applied either only once at one of the key growth stages [crown root initiation (CRI), booting, flowering, and grain filling], twice (two stages in various combinations), thrice (three stages in various combinations), or four times (all four stages). For ET-driven irrigation, irrigations were scheduled based on cumulative net ETo (ETo-rain) since the previous irrigation, for a range of net ETo (25, 75, 125, 150, and 175 mm). Five main irrigation schedules (SWD-based, ET-driven with irrigation applied after accumulation of either 75 or 125 mm of ETo, i.e., ET75 or ET125, and growth stage-based with irrigation applied at CRI plus booting, or at CRI plus booting plus flowering stage) were chosen for detailed analysis of yield, water balance, and CWP and IWP. Nitrogen was non-limiting in all the simulations.Mean Y_p across 36 years ranged from 5.2 t ha⁻¹ (10 October sowing) to 6.4 t ha⁻¹ (10 November sowing), with yield variations due to seasonal weather greater than variations across sowing dates. Yields under different irrigation scheduling, CWP and IWP were highest for 10 November sowing. Yields and CWP were higher for SWD and ET75-based irrigations on both soils, but IWP was higher for ET75-based irrigation on sandy loam and for ET150-based irrigation on loam. Simulation results suggest that yields, CWP, and IWP of PBW343 would be highest for sowing between late October and mid-November in the Indian Punjab. It is recommended that sowing be done within this planting period and that irrigation be applied based on the atmospheric demand and soil water status and not on the growth stage. Despite the potential limitations recognised with simulation results, we can conclude that DSSAT-CSM-CERES-Wheat V4.0 is a useful decision support system to help farmers to optimally schedule and manage irrigation in wheat grown in coarse-textured soils under declining groundwater table situations of the Indian Punjab. Further, the validated model and the simulation results can also be extrapolated to other areas with similar climatic and soil environments in Asia where crop, soil, weather, and management data are available.     

鸡粪便中氧氟沙星残留检测微生物法的建立

以金黄色葡萄球菌为工作菌, 用杯碟法测定氧氟沙星（OFL）在畜禽粪便中的残留。结果表明：鸡粪便中氧氟沙星的最低检测限为0.156μg/g,标准曲线的工作范围为0.156~5.00μg/g,工作曲线的日内变异系数在2.4%~3.3%、日间变异系数为3.7%~5.2%,回收率分别为79.49%~87.92%。因此,建立的方法可以满足鸡粪尿混合物中氧氟沙星的残留检测要求。     

油气含量测定方法的研究

研究了单体烃及油气色谱分析条件,建立了一套简单、便宜、准确的油气含量测定方法,研究了单体烃或油气-空气混合气中油气含量与色谱峰面积的关系、单体烃之间及其与油气之间的换算关系,并推导或回归出了相应的计算式。油气含量测定既可以油气总烃的标准谱图来换算,也可参照某单体烃标准谱图来换算。试验获得的基础数据及标定方法可供相关研究及管理部门作参考。     

Simulation and Validation of Rice Potential Growth Process in Zhejiang Province of China by Utilizing WOFOST Model

Since the pioneering work in the 1960s, substantial progress has been made in crop growth simulation both in developing and applying models. Crop growth simulation integrates the knowledge of computer science, phytophysiology, agroecology, agrometeorology, soil science, agronomy and systems, combines the plant and environmental factors, and describes quantitatively the dynamic relation between crop growth, development, yield formation and environmental techniques [1]. WOFOST (World Food Stu…     

Quantifying management-driven changes in organic matter turnover in an agricultural soil: An inverse modeling approach using historical data and a surrogate CENTURY-type model

In order to facilitate inverse modeling of time-series data and/or parameter estimation for process-based models of soil organic carbon (SOC) dynamics, we developed and applied a new surrogate CENTURY SOC model (SCSOC). While SCSOC has mass balance and decomposition kinetics equations for residue and soil organic matter (SOM) pools identical to those of CENTURY, it differs by being: (1) decoupled from models of plant growth, nutrient cycling, and hydrologic processes; (2) capable of employing daily, monthly, or annual timesteps; (3) solvable using widely available non-linear regression software. Here, we describe SCSOC and demonstrate that its numerical solution to the CENTURY SOC equations is highly accurate for both daily and monthly timesteps, provided the monthly physical forcing function inputs are appropriately derived from daily-resolution hydrologic model results.As an example of the proper application of the tool to obtain site-specific parameters and to investigate hypotheses using historical data, we analyzed SOC data from a single subplot of the Morrow Plots (Urbana, Illinois, U.S.A.) that has been cropped continuously in corn since 1876 using management practices that were common for east-central Illinois. The impact of different approaches typically used during calibration were examined by objectively estimating a variety of parameter sets that both govern SOM decomposition kinetics and define the initial mass and fractionation of the SOM. The results suggest that mean SOM turnover times were circa 5-fold longer during the period 1876-1954 relative to 1955-1995, when modern management practices were employed, and significantly different from default CENTURY predictions during both.Modified versions of SCSOC were also constructed in order to (1) show that uncertainty about historical soil erosion does not confound this interpretation of the data and (2) explore alternative assumptions about the structure of the model. One such alternate model showed that unexpectedly rapid decomposition of the corn-derived SOM combined with depletion of slowly-decomposing prairie-derived SOM could explain the post-1955 acceleration in decomposition.     

用多辐射校正水平遥感数据提取植被叶面积指数的精度分析

选用南京市SPOT5 HRG图像的地物反射率(PAC)、表观反射率(TOA)、星上辐射率(SR)和灰度值(DN)影像,提取了2种植被指数(VI),即归一化植被指数(NDVI)和比值植被指数(RVI),与地面实测的植被叶面积指数(LAI)进行了相关分析,并建立了157个LAI-VI关系模型。结果显示:LAI与VI呈显著的正相关关系(r=0.303~0.927,p0.01),对应不同植被的优选模型自变量包括了3个辐射校正水平的2种植被指数,可见基于不同辐射校正水平的植被指数在LAI遥感反演中具有一定的应用潜力。这些优选模型为:阔叶林:LAI=-3.345+5.378RVISR+7.329NDVISR(R2=0.818,RMSE=0.527),针阔混交林:LAI=1.696+17.076NDVIDN+137.684(NDVIDN)2-288.240(NDVIDN)3(R2=0.919,RMSE=0.440),灌木:LAI=-0.065+19.112NDVISR-113.820(NDVISR)2+184.207(NDVISR)3(R2=0.900,RMSE=0.448),草地:LAI=-5.905+6.446RVISR+9.477NDVISR(R2=0.944,RMSE=0.378),植被总体:LAI=-1.615+7.199NDVIDN+2.640NDVISR+2.105RVIPAC(R2=0.801,RMSE=0.668)。研究表明,基于不同植被类型、不同辐射校正水平影像的LAI遥感估算有利于充分挖掘遥感影像信息,进而提高LAI估算的精度。     

A new parallel framework of distributed SWAT calibration

With the development of large-scale hydrologic modeling, computational efficiency is becoming more and more important. Rapid modeling and analysis are needed to deal with emergency environmental disasters. The Soil and Water Assessment Tool(SWAT) is a popular hydrologic model, which is less applied in large-scale watershed simulation because of its sequential characteristics. For improving the computational efficiency of the SWAT model, we present a new parallel processing solution for hydrologic cycle and calibration based on MPI(Message Passing Interface). We partitioned sub-basins during the processes based on a load balancing method. Then the calibration was parallelized using a master-slave scheme, in which different input parameters were allocated to different processes to run the hydrologic cycle and compute the function value. Because of the slow convergence and local optimization of the SCE-UA(Shuffled Complex Evolution-developed by University of Arizona) algorithm in SWAT calibration, a genetic algorithm(GA) is developed to optimize the calibration step. Then by dividing the default communicator into several sub-communicators, all the hydrologic cycles were parallelized in their own sub-communicators to achieve further acceleration. In this paper the results show speedups for the hydrologic cycle calculations, as well as in the optimized calibration step. In the case study, we tested the parallel hydrologic cycle by four processes, and got a speedup of 3.06. In the calibration section, after applying the GA optimization, with 10 cores, we got a speed increase of 8.0 in our GA parallel framework compared with the GA sequential calibration, which is much better than the original SWAT calibration. After the sub-communicators added, this process was speeded up even further. The study demonstrated that the GA parallel framework with multi-sub-communicators is an effective and efficient solution for the hydrologists in large scale hydrology simulations.     

机器视觉核桃分级中相机可变视场与像素转换系数自动获取方法

针对利用机器视觉进行农产品无损检测中相机视场调节困难以及调整后需要重新标定的问题,提出一种基于MFC软件界面控制的大恒定焦USB 2.0工业相机视场自动调节方法,并通过试验对相机进行标定,拟合出相机高度和像素转换系数的关系式,当相机视场发生变化时,系统中超声波测高模块可以实时给出相机高度,程序根据关系式实时给出对应高度的像素转换系数,方便图像处理软件根据核桃轮廓像素数据换算出核桃尺寸,精确判断等级。     

农药残留检测方法中关于基质效应补偿的相关阀题探讨

农药残留检测过程中基质效应现象是影响定量准确度的关键因素之一,会对某些待测物的准确定量与定性造成影响,建立分析方法之前,必须要对待测物进行基质效应的评估。对农药残留分析中基质效应的涵义、表征、影响因素及补偿措施进行了总结,重点对基质匹配标准校正和分析物保护剂的应用等补偿与校正措施进行了阐述。