中国荒漠植物-土壤系统生态化学计量学研究进展

荒漠生态系统是中国陆地生态系统的重要组成部分,具有独特的结构和功能.生态化学计量学重点关注C、N、P元素比例及权衡关系,已成为揭示生态系统养分循环及其限制等生态过程的有力工具.植物自身体现出对养分元素的调控能力和对环境变化的响应及适应性,土壤C∶N∶P可表征土壤养分供应能力和储量变化,植物-土壤系统中N、P的养分循环关...     

新疆地下水热水特征及其与地震活动的关系

新疆地下热水广泛分布于昆仑山,天山和阿尔泰册。温泉和地震活动与大地构造,板块运动有着密切的联系。动态观测资料分析表明,热水温度变化不仅受到地震的作用,而且显示出某些地震前兆信息。分析了地下热水的化学成分,气体组分,微量元素,放射性元素,认为某些热水具有低矿化,高碱性,高氟,高氦等独特性质,有可能是形成于地壳深部或上地幔地深成水。     

GPS相位测量轨道改进基线定位

利用GPS载波相位观测值进行基线测定具有重要意义。本文讨论了基线测定中卫星星历误差对定位结果的影响,提出了基线上轨道改进的定位方法,编制了基线测定的定位软件,并使用高精度基线上的实际观测资料进行了计算。计算结果表明在基线上用轨道改进定位方法是可行的,可以提高定位精度。     

Geostatistical characterization of soil moisture and chloride distribution in deep vadose profiles of the Badain Jaran Desert,Northwestern China

Geostatistical analysis of soil moisture and ion accumulation can provide a deep understanding of aspects of a region’s hydrology such as recharge rates and flow paths. By combining this approach with detrended canonical correspondence analysis, the present study investigated the vertical and spatial variation of soil moisture and chloride (Cl^?) in vadose profiles of megadunes near lakes in the southeastern Badain Jaran Desert, northwestern China. Soil moisture varied vertically within the dune profiles following exponential, logarithmic, or log-normal distributions at different sites as a result of regulation by different local controls. The main local controls for Cl^? concentration were slope and orientation of the dune. Cl^? was not affected by local controls at depths >5 m. Sills of spatial variation in soil moisture and Cl^? in the variogram analysis were highly sensitive to local controls in the top 4 m of the profiles, and the values were three times those at depths >4 m. The lag for soil moisture was insensitive to local controls, and was 50–60 m in the top 4 m of the profiles and 20 m in deeper layers, whereas the lag for Cl^? was about 20 m at all depths. The results demonstrate that understanding recharge rates using factors such as Cl^? accumulation requires a careful survey to ensure that the local controls that regulate these factors are adequately accounted for.     

北京平原第四纪晚期花粉分析及其意义

毛主席曾经谆谆教导我们:“今天的中国是历史的中国的一个发展;我们是马克思主义的历史主义者,我们不应当割断历史”。研究社会应是这样,研究自然界也应是这样。因为现今的自然界是历史的自然界的最新阶段,如果我们要认识和改造今天的自然界,甚或企图去预测它将来的发展,那么我们就必须重视研究自然界的发展史,尤其是应注重研究与现今自然界密切相关的第四纪的发展史。     

Application of Monte-Carlo statistical experiments in design of ocean engineering——Estimating the parameters, models and probabilities

Recently, some results have been acquired with the Monte- Carlo statistical experiments in the design of ocean en gineering. The results show that Monte-Carlo statistical experiments can be widely used in estimating the parameters of wave statistical distributions, checking the probability model of the long- term wave extreme value distribution under a typhoon condition and calculating the failure probability of the ocean platforms.     

广海湾海浪要素的基本特征及典型台风过程的波浪分析

文中利用广海湾内长达49个月的实测海浪资料,对湾内海浪基本要素以及大浪过程与热带气旋活动的关系进行统计分析,并选取一个典型台风过程的波浪进行研究。结果表明:广海湾内波浪多以0~2级波高为主,出现频率达67%,3级波高次之,出现频率为32%,偶有4级波高出现;平均波高年变化幅度不大,但季节变化特征明显,最大波高的年变化和季节变化幅度均较大;大浪多出现在夏、秋季,与热带气旋活动密切相关;2008年9月强台风"黑格比"活动期间,测点观测到最大浪高达3.55m,形成5级以上大浪,台风浪波型经历了涌浪(有成熟的,也有未成熟的)-风浪-涌浪(未成熟的)的过程,符合一般台风浪波型的演变规律。     

Matter-wave interference in an axial triple-well optical dipole trap

This paper proposes a scheme of axial triple-well optical dipole trap by employing a simple optical system composed of a circular cosine grating and a lens. Three optical wells separated averagely by ～37 μm were created when illuminating by a YAG laser with power 1 mW. These wells with average trapping depth ～0.5 μK and volume ～74 μm³ are suitable to trap and manipulate an atomic Bose--Einstein condensation (BEC). Due to a controllable grating implemented by a spatial light modulator, an evolution between a triple-well trap and a single-well one is achievable by adjusting the height of potential barrier between adjacent wells. Based on this novel triple-well potentials, the loading and splitting of BEC, as well as the interference between three freely expanding BECs, are also numerically stimulated within the framework of mean-field treatment. By fitting three cosine functions with three Gaussian envelopes to interference fringe, the information of relative phases among three condensates is extracted.     

一种无人艇自适应无线通信系统的设计应用

随着无人艇技术的发展成熟,各型无人艇已逐步应用到民用和军用领域。无线通信系统作为无人艇的重要组成部分,承担着无人艇与母艇之间信息交互的功能。从无线通信技术的发展现状出发,分析出适用于无人艇应用场景的无线通信技术及工程设计方法,并设计了一种自适应无线通信系统。该系统能根据无人艇工作状态提供连续稳定的数据链,经试验测试,运行效果良好。     

不同地壳速度结构对安徽地区地震定位深度的影响

地震深度定位对地壳速度结构模型有较大的依赖性。选取2017年安徽及周边M_L 1.5以上地震,使用PTD与单纯型定位方法,分别配置华南模型与AH2015模型进行重新定位,研究不同模型对安徽地震深度的定位影响。研究表明,使用PTD方法,配置AH2015模型时定位深度略大,且符合安徽区域地震实际深度的记录台站较多;使用单纯型定位法,配置两种模型所得定位深度差距不大,且深度分布均匀。说明PTD方法定位地震深度对地壳速度结构模型的依赖程度较大,AH2015模型比华南模型更加符合安徽区域实际地壳结构。