GPS/GLONASS定位系统融合的坐标转换研究

GPS和GLONASS卫星定位系统分别采用WGS-84和PZ-90坐标系。为统一两种卫星定位成果,欧、美、俄于20世纪90年代各自求出两坐标系之间的转换参数。目前三种参数尚未统一,对GPS/GLONASS联合定位造成较大影响。本文针对国外介绍PZ-90和WGS-84坐标系相互转换时常用的转换模型及三种不同转换参数进行比较分析。分别选用地面GPS参考站坐标和GLONASS卫星轨道坐标,用三种坐标转换参数进行转换,对转换结果差异及其对单点定位和相对定位精度造成的影响进行全面分析比较,得出一些有益结论。     

Flocculation improves uptake of Sr and Cs from radioactive effluents

This paper presents the results of investigation on uptake of radioactive species ⁹⁰Sr and ¹³⁷Cs present in the liquid effluents from nuclear processing plants. Chemical precipitation process is adopted to remove radioactivity from the effluents with low and intermediate level of activity. In this process, radioactive ⁹⁰Sr and ¹³⁷Cs are co-precipitated along with copper ferrocyanide, ferric hydroxide and either calcium phosphate or barium sulphate. These precipitates being fine in size require flocculation for enhanced settling rate in clarifier/thickener. The flocculation by some selected high molecular weight polyacrylamide based polymers has improved the uptake of radioactive metal ions. The adsorption of these radioactive species has been found to increase in the presence of these flocculants thereby improving the decontamination factor (DF). While flocculating the precipitates, there may be some complex formation with Sr²⁺/Cs⁺, flocculant and the substrate. This has enhanced the uptake of the radioactive metal ions from the liquid component. The plant trials have indicated the improvement of DF value due to flocculation by cationic flocculant.     

Evidence for a seismic activity mainly constituted of hybrid events at Cayambe volcano,Ecuador. Interpretation in a iced-domes volcano context

The high activity level of Hybrid Events (HE) detected beneath the Cayambe volcano since 1989 has been more thoroughly investigated with data from a temporary array. The unusual HE spectral content allows separating a high-frequency signal riding on a low-frequency one, with a probable single source. HEs are interpreted as high frequency VT events, produced by the interaction between magmatic heat and an underground water system fed by thaw water from the summital glacier, which trigger simultaneous low-frequency fluid resonance in the highly fractured adjacent medium. Pure VTs are interpreted as ‘aborted’ HEs occurring probably in the oldest and coldest part of the volcano complex. To cite this article: B. Guillier, J.-L. Chatelain, C. R. Geoscience 338 (2006).     

Effect of a submerged bay-mouth breakwater on tsunami behavior analyzed by 2D/3D hybrid model simulation

The hybrid numerical model had been developed to simulate a complicated 3D flow around structures generated by tsunami. In the model, the conventional 2D model is adopted for the wide region far from structures and the 3D non-hydrostatic pressure model is used in the limited region adjacent to structures. The applicability of the model is shown by comparisons of the numerical results with the experimental results of the laboratory model tests and the numerical analysis results of the conventional whole 2D simulation. In addition, the effect of a submerged structure at the opening of a breakwater is discussed from the numerical simulations by the hybrid model. The submerged structure improves the stability of the rubble mound and reduces the tsunami inflow into the bay, while it increases the water surface velocity around the opening of the breakwater. The increase of surface velocity causes the increases of impulsive forces by collision with drafts and so on.     

岩浆混合作用——来自甘肃北山的野外证据

在 1∶2 5万马鬃山幅区调填图和方法研究工作中 ,通过观察到的一些与岩浆混合模式相关的现象 ,指出暗色微粒镁铁质包体是岩浆混合作用的有利证据 ,讨论了与花岗岩侵入体相关的镁铁质小岩体混合成因的可能性 ,认为岩浆混合作用在造山带岩浆活动中是一种极为普遍的现象。     

Hybrid vibration experiments with a bridge foundation system model

In order to improve seismic design technology of bridges, it is necessary to evaluate the vibration characteristics of a bridge–soil system that consists of soil, foundation structure, pier and superstructure. However, there have been few experimental studies on seismic behavior of bridge–soil system. In this paper, we conducted the hybrid vibration experiment on seismic behavior of bridge–soil system, and examined the applicability of hybrid vibration experiment to study seismic response of bridge–soil system. Based on the experiment results, seismic response of bridge was quantitatively studied.     

磁场重联中离子轨道的混合模拟研究

在使用2.5维混合模拟方法研究了Petschek模型稳态驱动磁场 重联演化的基础上， 本文考察了计算域内各典型区域中粒子分布函数的变化，描绘了重联区不同位置几种类型的 非Maxwell分布函数. 结果表明，磁场重联会将重联区少部分粒子加速到很高的能量，不同 加速程度的粒子将形成球壳状的速度分布. 粒子的轨道特征表明，在重联区中出流的粒子， 有一部分被磁镜捕获，其回旋半径大于重联区宽度，并构成整个流体速度的低速部分. 另外 ，在X中性点附近进入重联区的粒子沿磁力线向出流区以三种形式漂移，分别为：沿磁力线 逃逸、捕获在磁镜中随流体运动、横越磁力线漂移，其比例分别约为70%，20%和10%。     

螺旋坐标下的因子分解合成炮叠前深度偏移

在合成炮叠前深度偏移的基础上，提出了一种高效的合成炮叠前深度偏移方法，即在螺旋坐标下用因子分解进行波场外推的混合法. 用因子分解进行波场外推分为因果过程和反因果过程两个显式求解过程. 这种螺旋坐标下的显式求解过程,提高了波场外推的效率. 根据相位编码原理,对多个射线参数的合成波场进行了编码叠加,基于射线参数实现了MPI并行计算,进一步提高了计算效率. 在推导了有关公式并进行定量分析之后,对Marmousi复杂模型进行了计算,并作了比较,结果表明本文方法具有精度高和速度快的特点,可用于实际资料的计算.     

放养密度对大杂交鲟生长性能的影响及生理应答机制

为探讨放养密度对鱼类生长及生理应答机制的影响规律和作用,作者以大规格大杂交鲟(达氏鳇(Huso dauricus)♀×施氏鲟(Acipenser schrenckii)♂)为实验材料,研究了平均初始体质量约为243 g/尾,放养密度分别为6(SD1组)、9(SD2组)、12(SD3组)、15 kg/m3(SD4组)条件下,不同放养密度处理70 d后的实验鱼生长性能变化及生理应答机制。结果显示,放养密度对大杂交鲟肥满度影响不显著,SD2组鱼类具有最大的特定生长率和生长效率,随着放养密度增加,日增质量显著降低(P0.05),特定生长率和生长效率下降。测定了血液甲状腺素(T4)、三碘甲腺原氨酸(T3)和皮质醇水平变化,发现放养密度能引起大杂交鲟3个血液生理指标发生显著改变;随着养殖时间推移,T3和皮质醇浓度显著升高,T4浓度显著下降(P0.05)。这些结果说明神经内分泌活动的变化引起大杂交鲟血液生理指标变化,进而影响实验鱼生长性能。因此,在该养殖条件下推荐的养殖密度为9 kg/m3。     

Hybrid N-order Lagrangian Interpolation Eulerian?Lagrangian Method for Salinity Calculation

The Eulerian?Lagrangian method (ELM) has been used by many ocean models as the solution of the advection equation, but the numerical error caused by interpolation imposes restriction on its accuracy. In the present study, hybrid N-order Lagrangian interpolation ELM (LiELM) is put forward in which the N-order Lagrangian interpolation is used at first, then the lower order Lagrangian interpolation is applied in the points where the interpolation results are abnormally higher or lower. The calculation results of a step-shaped salinity advection model are analyzed, which show that higher order (N=3?8) LiELM can reduce the mean numerical error of salinity calculation, but the numerical oscillation error is still significant. Even number order LiELM makes larger numerical oscillation error than its adjacent odd number order LiELM. Hybrid N-order LiELM can remove numerical oscillation, and it significantly reduces the mean numerical error when N is even and the current is in fixed direction, while it makes less effect on mean numerical error when N is odd or the current direction changes periodically. Hybrid odd number order LiELM makes less mean numerical error than its adjacent even number order LiELM when the current is in the fixed direction, while the mean numerical error decreases as N increases when the current direction changes periodically, so odd number of N may be better for application. Among various types of Hybrid N-order LiELM, the scheme reducing N-order directly to 1st-order may be the optimal for synthetic selection of accuracy and computational efficiency.