Possible Impacts of High Temperatures on China’s Rice Yield under Climate Change

This study investigated the changes of high temperature events during important growing period of rice (graining filling to maturity) of 2021-2050 due to climate change. Future climate scenarios were HadGEM2-ES simulation with RCP2.6 and RCP8.5 emission pathways. Relationship between high temperature and yield change was established from historical weather and field observations during 1981-2009 period. The impacts of high temperatures on China’s rice production up to 2050 were assessed by applying deduced regression models to climate scenarios. Key messages drawn from this exercise include: ①High temperature event exhibited gradual increase from 2021 to 2050 under both RCP2.6 and RCP8.5 scenarios, characterized by increased number of high temperature days (HSD), rising accumulated temperature with Tmax greater than 35 ℃ (HDD), and increased lasting days of high temperature (CHD). The HSD and HDD increased substantially in double rice cropping system of South China, single rice cropping system of Yangtze River Basin and rice area of Northeast China. ②High temperature hotspot was located near the border between Hunan and Hubei during 1961-2000, and might move towards northeast in the period of 2021-2050. ③Except the Northeast, China’s rice production suffered most from increased HDD during grain filling to maturity, indicated by significant negative and linear relationship between yield and HDD, whereas rice in Northeast China was subject to the increase of SDD during grain filling to maturity, with a significant and quadratic relationship between the yield and SDD. ④Compared to the high temperature risks during 1961-1990, climate change would increase the risks in majority of the rice area, especially in Hubei and Anhui-the central portion of Yangtze River Basin rice area, Guangdong, Guangxi and Hainan-south China double rice area, and south part of Northeast China single rice area.     

赣东北蛇绿岩带新元古代(~800Ma)高镁安山岩的发现及其意义

在赣东北蛇绿岩带中的樟树墩地区新发现新元古代高镁安山岩,其LA-ICP-MS锆石U-Pb法年龄为794.8±6.0 Ma。它们的Si O2介于54.90%~58.45%,Al2O3介于15.31%~16.77%(平均小于16%);Ca O为2.46%~6.73%,Fe OT/Mg O变化于0.87~1.20,具有高Mg O(6.39%~8.76%)、高Mg#(64~71)特点;富集轻稀土元素且具弱负Eu异常,明显富集LILE而亏损HFSE,Sr含量(普遍200×10-6)和Sr/Y比值(4.11~7.29)均较低,具有典型高镁安山岩的地球化学特征,类似于日本Setouchi火山带的Sanukitoids。锆石εHf(t)值介于10.23~17.79之间,反映它们起源于亏损地幔。主、微量及同位素特征均表明,本区高镁安山岩是被俯冲板片释放的含水流体交代的地幔楔部分熔融的产物,形成于大洋岛弧(洋内弧)环境,指示赣东北地区在约800Ma前时仍存在洋壳俯冲,双溪坞弧尚未增生到扬子东南缘,暗示扬子和华夏两大陆块此时尚未碰撞拼合。     

内蒙古东乌旗迪彦钦阿木钼矿成矿流体氧逸度 特征及地质意义

迪彦钦阿木钼多金属矿床位于内蒙古自治区锡林郭勒盟东乌珠穆沁旗辖区内,是最近发现的远景储量达大型的钼矿床,其钼金属量0.7923Mt（Mo平均品位0.099%）。目前,关于该矿床的成矿地质特征、成矿年代、成矿物质来源、成因类型和成矿动力学背景等方面已有深入研究（聂秀兰和侯万荣,2010）,这些工作对认识该矿床成因及找矿预测起到很大帮助。但是,作为岩浆热液矿床的重要成矿介质,成矿流体的研究却显得较为薄弱,其中,成矿流体的氧逸度条件对于成矿作用起到至关重要的作用,具有重要的研究意义。因此,本次本文通过岩相学和矿相学研究,深入剖析了成矿流体的氧化还原条件,并对成矿流体的演化特征提出进一步的信息。     

Prediction of relative crest settlement of concrete-faced rockfill dams analyzed using an artificial neural network model

A neural network model has been developed for the prediction of relative crest settlement (RCS) of concrete-faced rockfill dams (CFRDs) using 30 databases of field data from seven countries (of which 21 were used for training and 9 for testing). The settlement values predicted using the optimum artificial neural network (ANN) model are in good agreement with these field data. A database prepared from reported crest settlement values of CFRDs after construction was used to train the ANN model to predict the RCS. It is demonstrated here that the model is capable of predicting accurately the relative crest settlement of CFRDs and is potentially applicable for general usage with knowledge of the three basic properties of a dam (void ratio, e; height, H; and vertical deformation modulus, E_V).

The performance of the new ANN model is compared with that of conventional methods based on the Clements theory and also with that of a proposed equation derived from the field data. The comparison indicates that the ANN model has strong potential and offers better performance than conventional methods when used as a quick interpolation and extrapolation tool. The conventional calculation model was proposed based on the fixed connection weights and bias factors of the optimum ANN structure. This method can support the dam engineer in predicting the relative crest settlement of a CFRD after impounding.     

High-temperature behaviour of melilite: in situ X-ray diffraction study of gehlenite–åkermanite–Na melilite solid solution

High-temperature X-ray diffraction experiments have been performed on melilite solid solutions, on single crystal and powder samples. In åkermanite–gehlenite series, the volumetric thermal expansion increases from gehlenite, 26.5(2) E-06 K-1, to åkermanite, 31.2(1) E-06 K-1. The variation is related to the cation content in the tetrahedral T1 site of the structure, and the linear expansion along the a axis has the greatest variation as a function of composition. The expansion perpendicular to the tetrahedral layers does not present any significant variation as a function of composition. In the åkermanite–Na melilite series, the presence of Na in the [8]-coordinated site strongly increases the linear expansion along the c axis, while the volumetric expansion decreases from åkermanite to Na melilite, whose value can be extrapolated to 27.4 E-06 K-1     

First-principles simulation of high-pressure polymorphs in MgAl<Subscript>2</Subscript>O<Subscript>4</Subscript>

We have used density functional theory to investigate the stability of MgAl₂O₄ polymorphs under pressure. Our results can reasonably explain the transition sequence of MgAl₂O₄ polymorphs observed in previous experiments. The spinel phase (stable at ambient conditions) dissociates into periclase and corundum at 14 GPa. With increasing pressure, a phase change from the two oxides to a calcium-ferrite phase occurs, and finally transforms to a calcium-titanate phase at 68 GPa. The calcium-titanate phase is stable up to at least 150 GPa, and we did not observe a stability field for a hexagonal phase or periclase + Rh₂O₃(II)-type Al₂O₃. The bulk moduli of the phases calculated in this study are in good agreement with those measured in high-pressure experiments. Our results differ from those of a previous study using similar methods. We attribute this inconsistency to an incomplete optimization of a cell shape and ionic positions at high pressures in the previous calculations.     

不同压力下Ⅰ型甲烷水合物拉曼光谱

本文描述了合成的Ⅰ型甲烷水合物高压下拉曼光谱测定结果。甲烷水合物用细粒冰和甲烷气在温度0℃～9℃和压力18MPa下历时2天合成,在金刚石压腔里进行了原位的显微观察和拉曼光谱测定。一组温度25℃和压力范围132～901MPa下的拉曼光谱数据显示,样品的光谱呈左高右低的双峰结构,左谱峰位置范围为2904.4～2907.2cm~(-1),右谱峰位置范围为2915～2922cm~(-1),谱峰位置随压力变化,典型光谱的左右谱峰强度比近似为3:1,系典型的Ⅰ型结构特征;这说明甲烷水合物在较高压力下也能保持Ⅰ型结构。作为比较,甲烷气和溶解水中的甲烷的拉曼光谱也进行了测定,它们的拉曼光谱特征与Ⅰ型甲烷水合物的明显不同。     

流体包裹体压力计研究之二:高温高压下碳氢化合物的拉曼光谱

在温度23～315℃、压力高达近2000MPa下用金刚石压腔下研究了正庚烷、环己烷及其混合物的拉曼光谱特征。结果表明：环己烷和正庚烷混合,只是改变了环己烷及正庚烷的平均C-H伸缩振动的拉曼位移,但是并不影响其P-△^-vp关系式。另外,经过数据拟合,得到了平均C-H伸缩振动的拉曼位移与压力的关系为：P=78．21（△^-vp）＋71．56。该公式可以用来作为流体包裹体尤其是油气包裹体的压力计。     

VHSR图像基于分割对象分类器性能评价

对比研究了平行六面体、最近邻分类法、最大似然法、神经网络等经典分类算法以及近年来新发展的支持向量机分类算法在基于分割对象的高分辨率遥感图像分类中的性能,详细分析了不同内积核函数对于支持向量机分类的影响。对两个试验区进行试验的结果表明,支持向量机分类算法分类精度得到明显改善,同时分类结果受参数、样本选择等影响较小,稳定性好。     

Large Rock Avalanches: A Kinematic Model

Rock avalanches constitute geodynamic phenomena of great beauty and extraordinary power, but at the same time they usually mean destruction of life found in their way. Therefore, it is of prime importance to acquire information on the dynamics of such debris streams so that their kinematic behavior can be evaluated in regions where they present a potential risk to human life and life in general. The energy loss due to dissipative interaction is greater than previously estimated. Starting with the energy conservation equation, one formula for the overall frictional loss, and another for the movement velocity of the predicted trajectory of a potential rock avalanche body is estimated.