用气象卫星资料估算吉林省主要农作物产量

净第一性生产力（Npp）分析是全球变化研究中广为利用的方法,利用气象卫星资料获得年际植被指数（Iv）估算Npp建立不同作物的Npp与其产量的关系模型,即可实现对粮食总产和不同作物产量的估算。文中介绍了应用净第一性生产力遥感（NPP—RS）模型对吉林省粮食总产和主要作物产量进行估算的方法。采用NPP—RS模型,对1995～2000年吉林省的粮食总产及主要农作物玉米、水稻产量进行了动态估算。对粮食总产估产的平均相对误差为13．6％,玉米的平均相对误差为17．6％,水稻的平均相对误差为6．7％。要提高用此方法进行遥感估产的精度,还需要对当年的种植制度、种植结构的变化有所了解,注意当年的灾情,增加灾害影响系数。     

气象条件对奶牛产奶量的影响及对策

在分析奶牛产奶量时间和空间分布的基础上,将乌兰浩特市全市产奶量和乌兰哈达奶牛场观测站产奶量与乌兰浩特市气象资料进行相关分析,确定了影响当地牛奶产量的关键气象因子和关键时期。结果表明,温度是当地春秋季节和冬季影响奶牛产奶量的主要限制因子,其次是气压和相对湿度,而降雨量和日照时数的影响不明显。     

深部开采底板隔水关键层受局部高承压水作用破坏理论分析

大量实测地质资料与防治水实践证实,深部煤层开采底板含水层存在大量的局部高承压水区域,在强开采扰动下极易诱发底板突水灾害。基于“下三带”、“关键层”理论,将局部高承压水与底板隔水关键层简化为圆筒力学模型,分析研究隔水关键层在局部高承压水作用下的屈服破坏机制,得到了隔水关键层发生屈服的4个临界水压值公式;对各临界水压值进行区间划分,分析不同区间隔水关键层的屈服状态,确定了局部高承压水致使隔水关键层屈服破坏两个阶段的水压判据平衡方程,得出了奥陶系顶部岩层作为隔水关键层剩余隔水能力的计算表达式,并反演得到了开采深度上限、下限公式。结合九龙矿深部开采实际,对所建力学模型进行了验证与应用,进而提出了防止局部高承压水致灾的相关措施,对实现深部煤层安全带压开采具有重要的理论指导意义。     

中西太平洋金枪鱼围网高产渔区年间变化及其原因分析

金枪鱼类是中西太平洋海域重要的经济鱼种,其中鲣产量约占到总产量的50%。本研究利用1995-2010年16年的中西太平洋（20°S~20°N,120°E~155°W）鲣围网生产统计数据和Niño3.4海区（5°S~5°N,120°~170°W）海表温度异常数据,对这16年鲣产量最高的十大渔区（5°×5°）进行时空格局分析,讨论渔场分布差异及CPUE与ENSO指数的关系。结果表明:16年间十大作业渔区主要分布在5°S~5°N、130°~175°E区域,这十大渔区产量占总产量的比重达47.5%,其中5°S~0°、155°~160°E,0°~5°N、130°~135°E,0°~5°N、135°~140°E及5°S~0°、160°~165°E等4个渔区产量占高产渔区产量的比重均超过10%,是中西太平洋重要的鲣产区。高产渔区的分布受海表温度影响较大,在厄尔尼诺时期,高产渔区分布明显偏东,主要分布在155°~180°E海域;在拉尼娜时期,高产渔区分布明显偏西,主要分布在130°~160°E海域。     

Rheological behavior of dredged slurries at high water contents

Each year in the world, there is significant amount of dredged slurries generated during geotechnical jobs. In the slurry storage process, the rheological behavior is a key factor affecting the motion of dredged slurries. To gain better understanding on this behavior, experiments on dredged slurries with different liquid limits are conducted using rotary viscometer. It has been found that, as water content increases, slurry property can change from Bingham plastic fluids to Newtonian fluids. In log–log coordinates, their corresponding yield stress and plastic viscosity are in linear relationship with their water contents and the intersection of these two lines can be treated as the turning point which is 4.7 times the liquid limit. The yield stress and plastic viscosity of different dredged slurries can be normalized efficiently using normalized water content. So, in this paper, a new quantitative prediction method for yield stress and plastic viscosity is proposed, which is effective for use in alkined modes of motion, is proposed.     

The Fractal Characteristics of Drainage Networks and Erosion Evolution Stages of Ten Kongduis in the Upper Reaches of the Yellow River,China

The fractal characteristics of drainage in the ten kongduis of the upper Yellow River were obtained using the box counting dimension, and the evolution stages of the watershed topography were defined by different ranges of the fractal dimensions of river networks (Dg). The results show that the fractal scaleless range of the Maobula River is 20–370 m based on a combination of artificial judgment, correlation coefficient test and fitting error. Other kongduis show good fractal characteristics in this fractal scaleless range as well. The box counting dimension can be used as a quantitative index of watershed topography fractal characteristics. The fractal dimension of stream networks is independent of the threshold contributing area used for extracting the drainage networks from the DEM. The values of Dg in the upper ten kongduis are in the range of 1.08?1.14. Both the runoff yield and the sediment yield are positively and linearly related with Dg. The positive relation between the sediment yield and Dg reflects the effect of landform features on sediment yield in the young and/or mature stages of landform evolution of the study area. By revising the critical value of Dg, the value of Dg of the basin in the young evolution stage is less than 1.06, while it is more than 1.06 for the basin in mature or old evolution stage. The upper ten kongduis are in the mature stage of landform evolution.     

Numerical modeling of water yield of mine in Yangzhuang Iron Mine,Anhui Province of China

This study develops a three-dimensional heterogeneous numerical model to simulate the water inrush process and predict the water yield for mineral exploration in Yangzhuang Iron Mine in Anhui Province. To identify the hydrogeological parameters of the aquifer in the study area, the model was calibrated and validated using the observed heads through the integrated trial-and-error and automated techniques. Also, the sensitivity analysis of the model was performed to evaluate the uncertainty associated with the calibrated model. According to the mine construction plan at different mining levels of -500 m, -600 m, and -700 m, the calibrated model was then applied to predict the water yields dependent on the different mining levels. As indicated by the prediction results, the numerical simulation model can systematically describe the groundwater system in the mining area and determine the source of water inrush in this iron mine. In conclusion, numerical analyses carried out in this study can provide guidance to decision-makers in balancing the iron ore mining and mine dewatering in the future.     

基于旁压试验土体弹塑性本构模型初探

在大量旁压试验数据分析的基础上,通过曲线拟合,建立了旁压试验弹塑性阶段曲线的椭圆方程,利用土体SMP屈服准则和Rowe流动法则,推导出土体塑性阶段应力增量与应变增量间关系矩阵。在弹性阶段,假设土体应力-应变服从广义虎克定律,建立了基于旁压试验的土体弹塑性本构模型。编制了相应的计算程序,将文中模型计算结果与实际旁压试验曲线进行对比,初步验证了模型的正确性。将本构模型编译为ABAQUS自定义材料子程序UMAT,通过有限元对比分析,文中模型计算变形较弹性模型小,较摩尔-库仑模型大,与模型建立的假设一致。基于旁压试验的土体弹塑性本构模型参数少,且易于获取,便于在实际工程中应用。     

汾河上游土地利用变化及其水文响应研究

以河岔水文站以上的汾河流域为研究区,采用土地利用转移矩阵和SWAT模型模拟方法,就汾河上游土地利用变化对水文过程的影响进行研究. 流域从1995-2000年,以耕地向林地和草地转变为主;从2000-2010年,城市建设用地不断增加,主要是对耕地的占用. 结果显示,在相同气候背景、不同土地利用情景（1995、2000年2010年）下,流域1992-2000年多年平均产水量微弱增加（分别为85.69 mm、85.75 mm和85.82 mm）,主要因为耕地持续减少,草地和城市建设用地不断增加. 但是各年产水量的大小关系不完全一致,枯水年和平水年与丰水年存在差异,而土壤水分呈现一致的减少状况. 子流域水平上,降水条件同样影响水文过程对土地利用变化的响应程度. 以上结果表明,汾河流域在退耕还林还草政策等影响下,土地利用发生变化并且直接影响流域的水文过程,但是流域水文过程对土地利用变化的响应还受到降水的影响.     

基于遥感的黄土高原林草植被变化对河川径流的影响分析

从黄土高原不同地貌区降雨产流机制入手,分析了林草植被影响流域水循环的可能环节;利用20世纪70年代以来不同时期的土地利用和植被盖度解译成果,以及同期实测的降雨和径流数据、供用水数据等,引入林草植被覆盖率、径流系数、产洪系数和基流系数等概念,从流域尺度上构建了林草植被覆盖率与河川径流的定量响应关系,结果发现,在半湿润或半干旱的黄土区,径流系数和产洪系数都将随林草植被的改善而减少,气候越干旱、径流或洪量减少越多;与同气候带的黄土区相比,盖沙黄土区林草植被改善所导致的减水量更大。不过,当林草植被覆盖率大于60%后,产洪系数变化减缓;最终河川径流将稳定在大于基流的某阈值附近。