Detection of UXO magnetic anomaly in Jinshan area

Magnetic survey is one of the most successful techniques for locating buried unexploded ordnances( UXO). For the location and identification of buried UXO in Jinshan area,a total-field magnetic survey is applied. The analytic signal of magnetic field is widely used to outline the boundaries of geology bodies,slightly dependent on the magnetization direction. In order to locate the UXO position,the analytic signal is applied to process the magnetic UXO data,which performs better than the conventional magnetic data. Then a typical UXO anomaly is extracted from the original data to invert for its depth by an improved Euler method proposed.The calculated depth is close to the real buried depth.     

区域地壳水平运动模型的Euler-GABP神经网络构建

针对传统的欧拉(Euler)矢量法在具有复杂构造运动的区域地区内构建GPS速度场模型精度低的问题,该文提出了欧拉矢量法结合遗传算法(GA)和BP神经网络方法来构建区域GPS速度场。以云南区域1999—2015年间的GPS速度场为实验数据,分别使用欧拉矢量法、遗传神经网络(GABP)、欧拉矢量结合神经网络(Euler-BP)和欧拉矢量的遗传神经网络(Euler-GABP)法构建区域速度场模型。实验结果表明,相比其他3种方法,该文提出的Euler-GABP方法在构建区域GPS速度场模型是可行和有效的且精度高。     

对偶四元数GPS辅助光束法区域网平差

针对GPS辅助光束法区域网平差中线元素和角元素分而治之引起转动和平移的耦合误差问题,该文提出了一种基于对偶四元数的GPS辅助光束法区域网平差方法。利用对偶四元数统一描述像空间坐标系与WGS84坐标系之间的旋转和平移关系,建立对偶四元数GPS辅助光束法区域网平差模型,实现了区域网影像外方位元素以及待定点WGS84坐标的平差解算。实验结果表明,本算法具有对迭代初值无依赖性、迭代次数少和精度高的优点,为姿态稳定较差的轻小无人机影像的GPS辅助光束法区域网平差提供了一种新的思路。     

FY-3A/MWHS冷空测值受月球影响分析及修正

为解决月球对风云三号卫星微波湿度计在轨实时辐射定标的影响问题,该文根据风云三号卫星微波湿度计在轨实时观测数据分析,通过多项式拟合分析技术,建立修正模型,消除月球影响,得到合理的辐射定标结果。风云三号卫星微波湿度计在轨实测数据分析表明:月球对风云三号卫星微波湿度计在轨辐射定标结果影响最严重时一天内可干扰4~5条轨道,每条轨道有近100个扫描周期受到污染。月球影响致使冷空定标观测数据跳升1000个计数值,如果不进行污染滤除会造成对地观测亮温下降约20 K,导致辐射资料无法同化进入数值天气预报模式。通过与同类载荷的交叉比对分析,修正月球影响后,风云三号卫星微波湿度计在轨实时辐射定标结果精度与在轨测试结果相当。     

Stochastic simulations of ocean waves: An uncertainty quantification study

The primary objective of this study is to introduce a stochastic framework based on generalized polynomial chaos (gPC) for uncertainty quantification in numerical ocean wave simulations. The techniques we present can be easily extended to other numerical ocean simulation applications. We perform stochastic simulations using a relatively new numerical method to simulate the HISWA (Hindcasting Shallow Water Waves) laboratory experiment for directional near-shore wave propagation and induced currents in a shallow-water wave basin. We solve the phased-averaged equation with hybrid discretization based on discontinuous Galerkin projections, spectral elements, and Fourier expansions. We first validate the deterministic solver by comparing our simulation results against the HISWA experimental data as well as against the numerical model SWAN (Simulating Waves Nearshore). We then perform sensitivity analysis to assess the effects of the parametrized source terms, current field, and boundary conditions. We employ an efficient sparse-grid stochastic collocation method that can treat many uncertain parameters simultaneously. We find that the depth-induced wave-breaking coefficient is the most important parameter compared to other tunable parameters in the source terms. The current field is modeled as random process with large variation but it does not seem to have a significant effect. Uncertainty in the source terms does not influence significantly the region before the submerged breaker whereas uncertainty in the incoming boundary conditions does. Considering simultaneously the uncertainties from the source terms and boundary conditions, we obtain numerical error bars that contain almost all experimental data, hence identifying the proper range of parameters in the action balance equation.     

DYNAMIC RESPONSE VARIABILITY OF STRUCTURES WITH UNCERTAIN PROPERTIES

A modal-based analysis of the dynamic response variability of multiple degree-of-freedom linear structures with uncertain parameters subjected to either deterministic or stochastic excitations is considered. A probabilistic methodology is presented in which random variables with specified probability distributions are used to quantify the parameter uncertainties. The uncertainty in the response due to uncertainties in the structural modelling and loading is quantified by various probabilistic measures such as mean, variance and coefficient of excess. The computation of these probabilistic measures is addressed. A series expansion involving orthogonal polynomials in terms of the system parameters is first used to model the response variability of each contributing mode. Linear equations for the coefficients of each series expansion are derived using the weighted residual method. Mode superposition is then used to derive analytical expressions for the variability and statistics of the uncertain response in terms of the coefficients of the series expansions for all contributing modes. A primary–secondary system and a ten-story building subjected to deterministic and stochastic loads are used to demonstrate the methodology, as well as evaluate its performance by comparing it to existing methods, including the computationally cost-efficient perturbation method.     

国家坐标系与城市坐标系转换方法的探讨

国家坐标系与城市坐标系之间的坐标转换是测绘实际作业过程经常遇到的一个技术难题,本文利用一个实例对相似转换法和多项式逼近法进行了比较研究,结果表明:对于大中型城市(大约方圆100公里左右),多项式逼近法的转换结果要优于相似转换法。     

Seismic comprehensive forecast based on modified project pursuit regression

In the research of projection pursuit for seismic comprehensive forecast, the algorithm of projection pursuit regression (PPR) is one of most applicable methods. But generally, the algorithm structure of the PPR is very complicated. By partial smooth regressions for many times, it has a large amount of calculation and complicated extrapolation, so it is easily trapped in partial solution. On the basis of the algorithm features of the PPR method, some solutions are given as below to aim at some shortcomings in the PPR calculation: to optimize project direction by using particle swarm optimization instead of Gauss-Newton algorithm, to simplify the optimal process with fitting ridge function by using Hermitian polynomial instead of piecewise linear regression. The overall optimal ridge function can be obtained without grouping the parameter optimization. The modeling capability and calculating accuracy of projection pursuit method are tested by means of numerical emulation technique on the basis of particle swarm optimization and Hermitian polynomial, and then applied to the seismic comprehensive forecasting models of poly-dimensional seismic time series and general disorder seismic samples. The calculation and analysis show that the projection pursuit model in this paper is characterized by simplicity, celerity and effectiveness. And this model is approved to have satisfactory effects in the real seismic comprehensive forecasting, which can be regarded as a comprehensive analysis method in seismic comprehensive forecast.     

基于粒子群优化的理论变异函数拟合方法研究

变异函数是地统计学中区域化变量空间结构分析和空间局部插值的主要分析工具.理论变异函数模型的获取是地质统计学中的基础性工作,它是了解区域化变量的变异特征、进一步对地质统计学计算的必要环节.针对现有的理论变异函数的拟合方法,如人工拟合法、线性规划拟合法、加权多项式拟合法、目标规划拟合法等的不足之处,充分利用粒子群优化算法在求解非线性优化问题时具有的全局寻优的特点,提出基于粒子群优化的理论变异函数拟合方法.在实例应用中,分别利用粒子群优化算法和加权多项式拟合方法进行理论变异函数拟合,交叉验证结果表明粒子群优化算法预测精度较高,具有较强的稳健性.     

随机地震动场多点激励下宽幅大跨桥梁结构地震响应研究

为了研究随机地震动场多点激励作用下宽幅大跨桥梁结构的地震响应,基于二维相干模型,考虑地震波非平稳性合成桥址各支承点的人工地震加速度时程波,采用多项式拟合法在时域内对各支承点处的人工合成加速度波进行校正,并对校正前后加速度波的响应谱进行比较校验;随后以某大跨自锚式悬索桥为例,利有限元软件中线性时程分析模块,将所合成的加速度地震波施加于结构,对比研究一致激励与随机地震动多点激励下宽幅大跨桥梁结构的地震响应。分析表明,考虑二维相干和地震波非平稳性合成的各支承点地震加速度时程波可采用多项式拟合法进行基线漂移现象的校正,同时应对修正前后加速度波的反应谱进行比较校验;对于大跨且横桥向支承点相距较远的桥梁结构应考虑横桥向地震波的非一致性。