新型水玻璃−酯类注浆材料及其固沙体特性研究

针对风积沙边坡稳定性差和常用加固技术存在成孔困难、加固范围有限等问题,提出以二元酸酯为固化剂的新型水玻璃?酯类浆液对风积沙进行加固的思路。采用倒杯法和旋转黏度计对新型水玻璃?酯类浆液的凝胶时间、黏度时变性进行了系统测试,并通过三轴试验研究不同浆液填充率对固沙体强度和渗透性的影响规律。研究表明：新型水玻璃?酯类浆液凝胶时间在20 s～60 min之间,浆液黏度随时间增长呈现指数型增长变化,且凝胶之前黏度低;当浆液填充率从0%增加至100%,固沙体黏聚力由0 kPa线性增加至148.4 kPa,内摩擦角按抛物线变化规律从32.1o增加至37.8o,渗透系数从3.42×10?5 cm/s降低到8.74×10?7 cm/s;与水玻璃?磷酸浆液、水玻璃?硫酸浆液相比,新型水玻璃?酯类浆液固沙体抗压强度高。该研究结果为风积沙边坡加固提供了新的方法。     

松辽平原典型黑土区有机质的变化及影响因素分析

根据2003～2008年松辽平原中南部地区多目标区域地球化学调查成果,研究了典型黑土区有机质的分布特征,提出了绥化-哈尔滨-四平一线典型黑土区有机质含量具有纬度地带性分布特点,有机质由北向南逐渐降低.分析了土壤有机质的影响因素,认为土壤的成土母质和土壤质地是决定有机质含量的重要基础,湖相沉积物和土壤质地细腻,黏粒成分多,有机质含量高.气温和降水等气候条件是影响土壤有机质的主要因素,低温湿润气候条件有利于有机质积累.耕地开垦时间长、作物连作和化肥使用等人为因素降低了有机质含量.     

波谱仪调制功率谱估计算法性能的仿真研究

基于星载波谱仪海浪方向谱探测原理,仿真了不同海况、风速下的海浪波谱仪接收信号,并采用周期图法、Welch法、AR模型法以及最小方差法共4种不同的调制谱估计方法反演出海浪谱,比较各种调制谱估计方法的海浪方向谱反演性能。仿真结果表明:对于一定方位向下的一维海浪谱反演,不同调制谱估计方法反演海浪谱性能优劣没有绝对的顺序。对于二维海浪谱反演,在成长中海浪条件下周期图法反演性能最差,其他3种方法的反演性能没有绝对优劣顺序;对于成熟风浪,最小方差法在积分能量误差、有效波高误差两个指标上的反演性能最好,在主波波向、主波波长误差上,周期图法反演性能最差,其他3种方法没有绝对优劣顺序。在涌浪条件下,AR模型法反演性能优于其他3种方法。在不同海况下,随着波谱仪中心入射角的下降,反演性能会下降。基于这些仿真结果,本文推荐最小方差法作为充分成长海浪的海浪方向谱反演的调制谱估计方法,AR模型法作为涌浪海浪方向谱反演的调制谱估计方法。     

Ecology of macrozoobenthic communities in two plateau lakes of Southwest China

Ecological studies on macrozoobenthos were conducted in two small plateau lakes in the Yunnan-Guizhou Plateau, Southwest China： Xingyun Lake （XL）, a eutrophic lake whose main source of primary production was phytoplankton （Chl α=99.76±24.01 μg/L）, and Yangzong Lake （YL）, a mesotrophic lake. Sampling was carried out from October 2002 to May 2004. Altogether 23 benthic taxa were identified in XL and 21 taxa in YL. The density of benthos in XL was much lower than that in YL, but the biomass was about equal in the two lakes, being I 423 ind/m^2 and 8.71 g/m^2 in XL and 4 249 ind/m^2 and 8.60 g/m^2 in YL. The dominant species were Limnodrilus hoffmeisteri, Branchiura sowerbyi, Aulodrilus pluriseta and Chironomus sp. in XL and Limnodrilus hoffrneisteri, Aulodrilus pluriseta and Bellamya sp. in YL. Seasonal fluctuation occurred, showing richer species in summer and winter, but the density and biomass varied in different ways in the two lakes. Analyses on functional feeding groups indicate that collector-gatherers were predominant, but the relative abundances of other groups were different. Stepwise multiple regression analysis demonstrated that the water depth, conductivity and chlorophyll a were the key factors affecting macrozoobenthic abundance in the lakes.     

Effects of sea states on seafloor compliance studies

Gas hydrates affect the bulk physical properties of marine sediments, in particular, elastic parameters. Shear modulus is an important parameter for estimating the distribution of hydrates in the marine sediments. However, S-wave information is difficult to recover without proper datasets. Seafloor compliance, the transfer function between pressure induced by surface gravity waves and the associated seafloor deformation, is one of few techniques to study shear modulus in the marine sediments. The coherence between recorded time series of displacement and pressure provides a measure of the quality of the calculated transfer function, the seafloor compliance. Thus, it is important to understand how to collect high coherence datasets. Here we conducted a 10-month pilot experiment using broadband seismic sensors and differential pressure gauges. We found that data collected in shallow water depth and during rough seas gave high coherence. This study is the first time long-term data sets have been employed to investigate seafloor compliance data quality and its dependence on sea state. These results will help designing future large-scale compliance experiments to study anomalously high shear moduli associated with the presence of gas hydrate or cold vents, or alternatively anomalously low shear moduli, associated with partial melt and magma chamber.     

Bending localization of nitrous oxide under anharmonicity and Fermi coupling: the dynamical potential approach

This paper studies the vibrational nonlinear dynamics of nitrous oxide with Fermi coupling between the symmetric stretching and bending coordinates by classical dynamical potential approach. This is a global approach in the sense that the overall dynamics is evidenced by the classical nonlinear variables such as the fixed points and the focus are on a set of levels instead of individual ones. The dynamics of nitrous oxide is demonstrated to be not so much dependent on the excitation energy. Moreover, the localized bending mode is shown to be ubiquitous in all the energy range studied.     

Drought Impacts on Vegetation Indices and Productivity of Terrestrial Ecosystems in Southwestern China During 2001–2012

Drought, as a recurring extreme climate event, affects the structure, function, and process of terrestrial ecosystems. Despite the increasing occurrence and intensity of the drought in the past decade in Southwestern China, the impacts of continuous drought events on vegetation in this region remain unclear. During 2001–2012, Southwestern China experienced the severe drought events from 2009 to 2011. Our aim is to characterize drought conditions in the Southwestern China and explore the impacts on the vegetation condition and terrestrial ecosystem productivity. The Standardized Precipitation Index(SPI) was used to characterize drought area and intensity and a light-use efficiency model was used to explore the effect of drought on the terrestrial ecosystem productivity with Moderate Resolution Imaging Spectrometer(MODIS) data. The SPI captured the major drought events in Southwestern China during the study period, indicated that the 12-year period of this study included both ‘normal' precipitation years and two severe drought events in 2009–2010 and 2011. Results showed that vegetation greenness(Normalized Difference Vegetation Index, NDVI and Enhanced Vegetation Index, EVI) both declined in 2009/2010 drought, but the 2011 drought resulted in less declines of vegetation greenness and productivity due to shorten drought duration and rising temperature. Meanwhile, it was about 5 months lapse between drought events and maximum declines in vegetation greenness for 2009/2010 drought events. In addition, forest, grassland and cropland revealed significant different ecosystem responses to drought. It indicated that grassland showed an early sensitivity to drought, while cropland was the most sensitive to water deficit and forest was more resilient to drought. This study suggests that it is necessary to detect the difference responses of ecosystem to drought in a regional area with satellite data and ecosystem model.     

Liebermannite,KAlSi3O8, a new shock-metamorphic,high-pressure mineral from the Zagami Martian meteorite

In this paper, we discuss the occurrence of liebermannite (IMA 2013-128), KAlSi₃O₈, a new, shock-generated, high-pressure tetragonal hollandite-type structure silicate mineral, in the Zagami basaltic shergottite meteorite. Liebermannite crystallizes in space group I4/m with Z = 2, cell dimensions of a = 9.15 ± 0.14 (1σ) Å, c = 2.74 ± 0.13 Å, and a cell volume of 229 ± 19 Å³ (for the type material), as revealed by synchrotron diffraction. In Zagami, liebermannite likely formed via solid-state transformation of primary igneous K-feldspar during an impact event that achieved pressures of ~20 GPa or more. The mineral name is in honor of Robert C. Liebermann, a high-pressure mineral physicist at Stony Brook University, New York, USA.     

利用深度学习预报美国东北部日降水分布

现阶段降水预报主要依靠数值天气预报模式。但受物理参数化、计算资源等因素的影响,基于数值模式的降水预报还存在非常大的不确定性。近年来,深度学习在天气预报领域显示出巨大优势和潜力。本文通过构建神经网络预报美国东北部日降水分布,探讨神经网络模型基于低分辨率气象场(ERA-Interim, 0.7°)预报高分辨率降水(CPC,0.25°)的能力,并比较3种主流网络框架(VGG,ResNet, GoogleNet)在该任务中的表现。结果表明,3种网络框架都对美国东北部日降水分布具有一定的预报能力(VGG框架表现最优),但三者的均方根误差(RMSE)均高于ERA-Interim 24-h(ERA24)的降水预报。3种神经网络的集合预报结果优于ERA24预报,且这三者与ERA24预报结果的集合平均能够显著提高ERA24对不同季节、不同强度降水的预报。     

The complete mitochondrial genome of Parachiloglanis hodgarti and its phylogenetic position within Sisoridae

The complete mitogenome of Parachiloglanis hodgarti was sequenced and characterized, which is the first mitogenome of the genus Parachiloglanis within Sisoridae. The mitogenome is 16 511-bp long and included 13 protein-coding genes, 22 transfer RNAs, two ribosomal RNAs, and one control region. The genome composition was A+T biased (58.64%) and exhibited a positive AT-skew (0.095) and a negative GC-skew (?0.283). Compared with other Sisoridae fishes, the characteristics of nucleotide skews, codon usage, and amino acid usage of the P. hodgarti mitogenome are more similar to those of non-Glyptosternoid fishes. Furthermore, the phylogenetic trees show that Sisoridae fishes fall into four major clades and P. hodgarti (Clade I) is basal to the Sisoridae family, forming a sister clade to the Glyptosternoids (Clade IV). The topological structures constructed in this study raised doubts over the traditional classification system. These results will help better understand the features of the P. hodgarti mitogenome and provide a reference for further phylogenetic research on Sisoridae species.