解析延拓解及借助地形数据解的模型检验

本文利用位于参考平面上的无限延仲的三棱质体模型检验了解析延拓解(至一次项)和借助地形数据解在解算垂线偏差时的精度,并对这两个解在理论上和实用上的优劣程度进行了详细分析,得到了在计算垂线偏差时加入解析延拓解的一次项的精度还不如直接用法耶异常代入Venig Meinesz公式的精度高的新论点,并进一步验证了借助地形数据解的精确性和在实用中的优越性。     

作物气象灾害危害性的多目标灰色局势决策

利用灰色局势决策中的最优局势概念及其决策方法，对广西主作物冷、旱、涝方面的不同灾害类型，设置作物气候减产率，单位面积产值损失，灾害机率三个方面的分析目标，并以灾害类型作事件集（Ａ＝ａｉ，ｉ＝１，２．．．，ｎ）、以广西８个地区作决策集（Ｂ＝ｂｊ，ｊ＝１，２，．．．，８），构造成多目标灰色局势。经局势优化后，得到更为明晰的各地区冷、旱、涝灾害危害性的决策结果，从而了解到７种灾害类型中，哪一种类型的灾害     

一种低成本、低精度SINS/GPS组合导航系统及试验研究

在SINS（捷联式惯性导航系统）与GPS组合时，航向角的可观测性较弱，经过卡尔曼滤波后，航向角误差虽有所改善，但仍呈发散趋势，当采用低成本、低精度SINS时，该趋势进一步加剧。为了抑制该发散趋势，针对某型低成本、低精度SINS硬件组成（包括AHRS（姿态和航向参考系统）与IMU（惯性测量器件））的特点，提出了利用AHRS代替SINS航向角信息的方法。实际静态与动态试验表明，利用该方法可有效地抑制组合系统航向角的发散趋势，定位精度较高。     

Benthic Oxygen Consumption and Organic Matter Turnover in Organic-poor, Permeable Shelf Sands

The high permeability of sediments and strong near-bottom currents cause seawater to infiltrate the surface layers of Middle Atlantic Bight shelf deposits. In this study, sandy sediment cores from 11 to 12 m water depth were percolated with filtered seawater on shipboard. Sedimentary oxygen consumption (SOC) increased non-linearly with pore water flow, approaching maximum rates of 120 mmol m⁻² d⁻¹ (May 2001) or 75 mmol m⁻² d⁻¹(July 2001). The addition of acetate to the inflowing water promptly enhanced the release of dissolved inorganic carbon (DIC) from the cores. DIC production rates were a linear function of acetate concentration, ranging from 100 to 300 mmol m⁻² d⁻¹ without substrate addition to 572 mmol m⁻² d⁻¹ with 100 mM acetate. The sediments also hydrolyzed a glucose pseudopolymer, and the liberated glucose prompted an increase of SOC. Our results suggest that decomposition rates of organic matter in permeable sands can exceed those of fine-grained, organic-rich deposits, when water currents cause advective interstitial flow, supplying the subsurface microbial community with degradable material and electron acceptors. We conclude that the highly permeable sand beds of the Middle Atlantic Bight are responsive within minutes to hours and efficiently operate as biocatalytical filters.     

Strip-focused phreatic surface flow driven by evaporation: Analytical solution by the Riesenkampf function

Steady free-surface seepage in a homogeneous porous aquifer is studied by a conformal mapping of the inversed hodograph (angle) onto the domain in the Riesenkampf plane (slanted-face half-strip or trapezium). Seepage from the water table is caused by evaporation uniformly distributed with a horizontal coordinate. This distributed sink forms a regional trough on the phreatic surface with groundwater moving from the flanks to the trough center on the regional scale and from the water table to the soil surface locally. The free surfaces, streamlines of marked particles, travel times, and Darcian velocity are presented.     

一种约化序贯最小二乘解法

平方根最小二乘法是解决传统最小二乘估计中法方程奇异的有效方法之一，但是，当观测方程具有大量局部参量时，直接使用该方法并不可取。基于等效观测方程思想，本文提出了一种能够约化局部参数的序贯最小二乘算法。     

Gross Error Compensation for Gravity Field Analysis Based on Kinematic Orbit Data

This paper aims at a comparative study of several measures to compensate for gross errors in kinematic orbit data. It starts with a simulation study on the influence of a single outlier in the orbit data on the gravity field solution. It is shown that even a single outlier can degrade the resulting gravity field solution considerably. To compensate for outliers, two different strategies are investigated: wavelet filters, which detect and eliminate gross errors, and robust estimators, which due to an iterative downweighting gradually ignore those observations that lead to large residuals. Both methods are applied in the scope of the analysis of a 2-year kinematic CHAMP (challenging minisatellite payload) orbit data set. In various real data studies, robust estimators outperform wavelet filters in terms of resolution of the derived gravity field solution. This superior performance is at the cost of computational load, as robust estimators are implemented iteratively and require the solution of large sets of linear equations several times.     

Comparing DGPS corrections prediction using neural network, fuzzy neural network, and Kalman filter

Position information obtained from standard global positioning system (GPS) receivers has time variant errors. For effective use of GPS information in a navigation system, it is essential to model these errors. A new approach is presented for improving positioning accuracy using neural network (NN), fuzzy neural network (FNN), and Kalman filter (KF). These methods predict the position components’ errors that are used as differential GPS (DGPS) corrections in real-time positioning. Method validity is verified with experimental data from an actual data collection, before and after selective availability (SA) error. The result is a highly effective estimation technique for accurate positioning, so that positioning accuracy is drastically improved to less than 0.40 m, independent of SA error. The experimental test results with real data emphasize that the total performance of NN is better than FNN and KF considering the trade-off between accuracy and speed for DGPS corrections prediction.     

Combining geographic information system, multicriteria evaluation techniques and fuzzy logic in siting MSW landfills

This study presents a methodology for siting municipal solid waste landfills, coupling geographic information systems (GIS), fuzzy logic, and multicriteria evaluation techniques. Both exclusionary and non-exclusionary criteria are used. Factors, i.e., non-exclusionary criteria, are divided in two distinct groups which do not have the same level of trade off. The first group comprises factors related to the physical environment, which cannot be expressed in terms of monetary cost and, therefore, they do not easily trade off. The second group includes those factors related to human activities, i.e., socioeconomic factors, which can be expressed as financial cost, thus showing a high level of trade off. GIS are used for geographic data acquisition and processing. The analytical hierarchy process (AHP) is the multicriteria evaluation technique used, enhanced with fuzzy factor standardization. Besides assigning weights to factors through the AHP, control over the level of risk and trade off in the siting process is achieved through a second set of weights, i.e., order weights, applied to factors in each factor group, on a pixel-by-pixel basis, thus taking into account the local site characteristics. The method has been applied to Evros prefecture (NE Greece), an area of approximately 4,000 km². The siting methodology results in two intermediate suitability maps, one related to environmental and the other to socioeconomic criteria. Combination of the two intermediate maps results in the final composite suitability map for landfill siting.     

基于小波包分析的地震资料联合去噪方法研究

在地震记录中,随机噪声严重影响了有效信号的提取,为此必须进行消噪处理。这里首先使用小波包变换对不同频段的信号进行精细分离,有效信号和噪声经小波包分解后,其小波包系数将表现出不同特性,然后根据这种不同特性进行去噪处理,对小波包分析法处理后的剩余地震信号再进行KL(Karhunen-Loeve)变换,提取相关有效信号,最后对提取的有效信号进行中值滤波处理,进一步去除剩余噪声。经合成地震剖面和实际地震剖面处理实验证明,小波包分析、KL变换和中值滤波联合去噪方法,能有效地消除较强的随机噪声,提高地震剖面信噪比和分辨率。