Predicting Bathymetry from the Earth's Gravity Gradient Anomalies

Historically, prediction of ocean floor depth, or bathymetry, has been based on the isostatic modeling and linearized relationships between gravity anomalies and bathymetry. The need for isostatic modeling limits the application of the resulting bathymetry predictions as constraints in geophysical models. An alternative technique making use of the Earth's vertical gravity gradient for predicting bathymetry is explored in this paper. This technique is based on the fact that the observed gravity gradient anomalies result primarily from local mass concentrations on the ocean floor, and that mass compensation by the oceanic crust has an insignificant effect on the gravity gradients, and can be neglected. The resulting bathymetry prediction therefore is independent of isostatic modeling assumptions, allowing it to be used as a constraint on models of lithospheric compensation and for other geodetic and geophysical applications.     

Approximate Stream Function wavemaker theory for highly non-linear waves in wave flumes

An approximate Stream Function wavemaker theory for highly non-linear regular waves in flumes is presented. This theory is based on an ad hoc unified wave-generation method that combines linear fully dispersive wavemaker theory and wave generation for non-linear shallow water waves. This is done by applying a dispersion correction to the paddle position obtained for non-linear long waves. The method is validated by a number of wave flume experiments while comparing with results of linear wavemaker theory, second-order wavemaker theory and Cnoidal wavemaker theory within its range of application.     

Dynamic Modeling and Three-Dimensional Motion Analysis of Underwater Gliders

For Cconsideration ofing both the eccentric rotatable rigid body and the translational rigid body, the dynamic model of the underwater glider is derived. Dynamical behaviors are also studied based on the model and can be used as the guidance to underwater gliders design. Gibbs function of the underwater glider system is derived first, and then the nonlinear dynamic model is obtained by use of Apell Equations. The relationships between dynamical behaviors and design parameters are studied by solving the dynamic model. The spiral motion, swerving motion in three dimensions and the saw-tooth motion of the underwater glider in vertical plane are studied. Lake trials are carried out to validate the dynamic model.     

Reduction of disparities in access to green spaces: Their geographic insertion and recreational functions matter

Green spaces (GS) have many functions that can moderate the climate change impact and help prevent disease and thus alleviate public health expenses in a context of aging societies. However, several socioeconomic, demographic and geographic processes may render the access to GS challenging. Moreover, it is often critical to know what type of GS service to develop at a specific place. Also, measurements accuracy issues could be critical for planning and decision making. As an example of what could happen in many other cities of different sizes, we modeled and compared the access to GS, including several of their specific functions, in the Census Metropolitan Areas (CMA) of Montreal and Quebec City in Canada. We used the Quebec Integrated Chronic Disease Surveillance System (QICDSS) (average of 3 million people per year over 1996–2011) to measure over time, the proximity of each individual to the closest GS boundary using travel costs and spatial interaction models. ANOVA models and their corresponding base regressions were used to evaluate the statistical significance of the relationship of GS distances and surface to density, deprivation, gender and age, including interaction terms. The spatial clustering of the reduction of distances to GS was evaluated on a chronological basis. Unlike the larger CMA of Montreal, Québec City CMA showed greater equity in access to GS, largely due to the specific geographic insertion of linear GS. The CMA of Montreal showed an improvement in the access to GS which benefits the wealthy in the densest areas on the island of Montreal. Everything happens as if a green gentrification process affects the access to GS in Montreal. Our results suggest that for the promotion of GS as an important element of primary prevention in public health, both the quality or functions of GS and the geographic determinants of their access are of higher importance than a simple consideration of total GS surface per capita as often used by decision makers or public health promoters. They also underline the limits of standard measurements of attraction and accessibility and the complexity for large cities to promote environmental justice, given the complexity of their socio-demographic processes.     

超大型浮体水弹性分析的平板格林函数法

采用Eatock Taylor ＆ Ohkusu提出的一种矩形平板的挠度格林函数进行超大型浮式结构物在波浪中的水弹性响应分析，计算结果与试验结果比较，相当吻合，证实此平板挠度格林函数可以用于超大型浮式结构物的水弹性分析。     

Simultaneous Non-linear Retrieval of Atmospheric Temperature and Absorbing Constituent Profiles from Satellite Infrared Sounder Radiances

Based on Zeng’s theory (1974), a successive linearized form of radiative transfer equation (RTE) is derived for simultaneous retrieval of atmospheric temperature and absorbing constituent profiles from satellite infrared observa-tions. It contains the temperature component weighting function and absorbing constituent (H2O, O3, CH4 etc.) com-ponent weighting functions. All these weighting functions reach maximum at their own “optimum information levels”, and make the remote sensing equations well-conditional. Then the atmospheric profiles are derived by Newton’s non-linear iteration method. Experiments of retrieval from both TIROS-N operational High Resolution Infrared Sounder (HIRS) and the simulated Atmospheric infRared Sounder (AIRS) show an significant improvement.     

大气折射的映射函数与神经网络拟合比较分析

首先介绍映射函数和神经网络模拟方法在大气折射研究领域中的应用情况,总结映射函数的基本形式,分析BPNN的基本原理,进而研究了基本映射函数的BPNN变换。最终利用普尔科沃大气折射表这一数据平台与MATLAB7中的神经网络工具箱,建立与映射函数对应的BPNN模型,对普尔科沃大气折射表进行BPNN模拟。与相关文献的映射函数模拟进行比较分析:BPNN的模拟精度是4阶分式映射函数的2倍,不仅证明大气折射的映射函数模拟存在较大的拟合残差,而且表明BPNN对大气折射的非线性拟合优于映射函数,同时也为BPNN的隐层神经元具备挖掘高阶隐含信息提供了一个研究实例。     

非量测型无人机影像快速大比例尺数字成图探讨

利用小型无人机非量测型影像进行大比例尺测绘成图是目前研究的热点。利用无人机快速高效、影像清晰的特点,少量外业控制点参与,在CASS软件下获取大比例尺数字图是一个有效方案。结合PCI软件有理多项式的解算方法,检测非量测型无人机影像所制作的正射影像和测图成果精度。实践证明,此方法可以快速获取符合规范要求的测图成果。     

档案达标检查在地震档案管理中的作用

档案达标检查在档案管理工作中起着重要的作用,是促进档案工作规范化、标准化的有效手段,尤其对专业性很强的地震档案工作起着重要的指导作用。     

用内插拟合的方法确定大地水准面

GPS平面精度之高已被人们共识和接受,但其高程精度如何,一直是人们普遍关心的问题。本文综合利用GPS测量成果和水准测量资料,采用两种方法拟合高程异常在区域中的分布,用剩余已测点的数据对其进行检验,计算及比较各种方法的拟合精度。通过对实测数据的计算分析和发现,GPS高程用于确定正常高是有使用价值的。