Polynomial approximate solutions to the Boussinesq equation

We provide closed-form approximate solutions to models of horizontal infiltration described by the Boussinesq equation in a semi-infinite aquifer that is initially dry. The approximations preserve such important qualitative properties as scaling and wetting fronts. They are applicable to four types of boundary conditions, two on head and two on flux, enumerated in the paper. All the considered problems admit self-similar variables that allow reduction to boundary value problems for a nonlinear ordinary differential equation. This work extends recent results by Lockington et al. [Lockington DA, Parlange J-Y, Parlange MB, Selker J. Similarity solution of the Boussinesq equation. Adv Water Resour 2000;23(7):725–9] and Telyakovskiy et al. [Telyakovskiy AS, Braga GA, Furtado F. Approximate similarity solutions to the Boussinesq equation. Adv Water Resour 2002;25(2):191–4], with new approximations developed for two of the four cases and a new extension of a previously existing method for a third case. Numerical results extending the work of Shampine [Shampine LF. Some singular concentration dependent diffusion problems. ZAMM 1973;53:421–2] provide a basis for assessing the accuracy of the new methods.     

GPS作业过程中的质量控制初探

从GPS作业过程的网形设计、外业观测和基线解算等方面简述了在GPS静态定位测量中影响质量的主要因素,并对网形设计、外业观测和基线解算进行了分析,详细分析了影响GPS基线解算结果的主要因素,给出了判别这些因素方法,并对如何消除这些因素的影响提出了相应的处理措施。     

Post-stack impedance blocky inversion based on analytic solution of viscous acoustic wave equation

The conventional impedance inversion method ignores the attenuation effect, transmission loss and inter-layer multiple waves; the smooth-like regularization approach makes the corresponding impedance solution excessively smooth. Both fundamentally limit the resolution of impedance result and lead to the inadequate ability of boundary characterization. Therefore, a post-stack impedance blocky inversion method based on the analytic solution of viscous acoustic equation is proposed. Based on the derived recursive formula of reflections, the 1D viscous acoustic wave equation is solved analytically to obtain zero-offset full-wave field response. Applying chain rule, the analytical expression of the Fréchet derivative is derived for gradient-descent non-linear inversion. Combined with smooth constraints, the blocky constraints can be introduced into the Bayesian inference framework to obtain stable and well-defined inversion results. According to the above theory, we firstly use model data to analyse the influence of incompleteness of forward method on seismic response, and further verify the effectiveness of the proposed method. Then the Q-value sensitivity analysis of seismic trace is carried out to reduce the difficulty of Q-value estimation. Finally, the real data from Lower Congo Basin in West Africa indicate that the proposed approach provide the high-resolution and well-defined impedance result. As a supplement and development of linear impedance inversion method, the non-linear viscous inversion could recover more realistic and reliable impedance profiles.     

Design and routing of storm flows in an urbanized watershed without surface streams

In the karst geologic setting of Greenbrier County, West Virginia, USA, the drainage network in the watersheds do not support surface streams, but depend entirely on sinkholes, solution cavities, or injection wells as discharge points for accumulated storm water. By providing a systematic framework for designing and routing storms in this geologic setting, functioning retention and attenuation structures have been developed which are protective of water quality while still safely discharging storm water in a controlled manner to the subsurface. This article provides a rationale for the design methodology and then examines the successful implementation of an attenuation and storm water retention design to manage the surface discharges for an entire watershed. By examining the pre-development flows and evaluating future land use patterns (i.e., installation of impermeable surfaces over large areas), as well as sinkhole conveyance capabilities, it was necessary to examine alternative disposal options for collected storm water as well as devise a basin-wide management strategy to coordinate future development of the watershed. Additionally, innovative water quality measures were implemented to help prevent contamination from preferentially infiltrating into the subsurface as a result of these land development activities.     

基于自适应遗传算法的MRS-TEM联合反演方法研究

地面磁共振法(MRS)因具有定性、定量分析地下水能力,而备受关注.传统磁共振地层含水量反演多采用均匀半空间模型,忽略电阻率分布信息对结果的影响.针对这一问题,本文基于多层电介质中磁共振响应理论,提出MRS与瞬变电磁(TEM)联合反演方法,通过电阻率分布信息对含水量反演过程的实时修正,提高了解释结果的准确度.反演算法采用自适应遗传算法(AGA)进行,基于繁殖规则,动态调整交叉概率和变异概率,解决了标准遗传算法易未成熟收敛而难以得到全局最优解问题.模型数据表明,含噪10%情况下,联合反演仍能较准确地反映地下含水单元模型结构,对比MRS单独反演优势明显.同时,内蒙古白旗野外观测数据联合反演结果与钻井资料基本一致,充分验证了AGA反演算法的实用性及MRS-TEM联合反演的实际意义.     

江西桃山大布铀矿床实验室溶浸工艺试验研究

本文介绍了大布铀矿床的物质成分、该类型铀矿提取和回收工艺条件的研究及取得的最佳溶浸工艺参数。试验表明,大布矿床铀浸出性能好,酸耗低,用溶浸法开采具有良好的前景。与常规工艺试验相比,该研究工作的主要特点表现为：溶浸剂的硫酸配方改变了常规工艺从高到低的布液方式,采用由低到高再低的方式,有效地避免了硫酸钙的沉淀;选择了廉价高效的氧化剂,提高了浸出率。通过工艺试验为下一步开展堆浸或原地破碎浸出半工业试验,重新评价桃山矿田提供了技术依据。     

Lower bound limit loads of ship structure components using the mα-tangent method based on single linear elastic analysis

Limit loads for ship structure components are determined in this paper based on a single linear elastic finite element analysis by invoking the concept of kinematically active reference volume in conjunction with the m_α-tangent method. The method enables rapid determination of lower bound limit loads for ship structure components by taking their kinematically inactive volume into consideration. This method is applied to a number of ship structure components possessing different percentages of inactive volume. Results are compared with the corresponding inelastic finite element results, and available analytical solutions.     

Grain-size-sensitive creep of plagioclase accompanied by solution–precipitation and mass transfer under mid-crustal conditions

We report here on a study of three deformed granitoids: two mylonites and an ultramylonite from the inner ductile shear zone of the Ryoke metamorphic belt, SW Japan. Monophase layers composed of quartz, plagioclase or K-feldspar are present in all samples. The plagioclase-rich layers consist of grains 6–10 μm in size, and sometimes include patchy K-feldspar and quartz, indicating solution-precipitation. In the mylonite, the fine-grained plagioclase is mainly An_23–25 and, the composition of plagioclase porphyroclast is An_21–39 without any significant maximum. The An compositions together with textural observations indicate that fine-grained plagioclase nucleated from solution with mass transfer during deformation. In the ultramylonite, fine-grained plagioclase is widely changed to be An_15–37, indicating that the grain-size-reduction process includes fracturing of original plagioclase porphyroclasts in addition to the solution–precipitation process, which results in the composition concentrated around An₃₀. In all samples, the crystallographic orientations of fine-grained plagioclases are almost random and do not correlate with neighbouring porphyroclasts. Grain-size-sensitive creep occurred during rock deformation subsequent to the process of solution–precipitation that involved mass transfer via fluids.     

Luminescence dating of sediments from a Palaeolithic site associated with a solution feature on the North Downs of Kent,UK

Optically stimulated luminescence (OSL) dating has been applied to determine the burial age of sediment horizons within a sequence containing Lower Palaeolithic artefacts on an upland site associated with a solution feature (doline) at West Cliffe, located on the North Downs in Kent, UK. The study makes use of a novel extension of the single aliquot OSL measurement procedure to investigate the nature of significant overdispersion in equivalent dose values with very small aliquots of quartz inclusions, enabling single grain resolution to be approached with ∼90 μm diameter quartz extracted from the relatively fine-grained brickearth. A detailed examination of the uniformity of the distribution of radionuclide sources in the sampled volumes was also performed and this included the application of a spatially-resolved technique for beta dose rate measurement. The OSL ages, obtained for the burial of brickearth positioned stratigraphically below and above a clay and flint clast layer containing the artefacts and debitage, place the deposition of the artefacts to between ca 140 and 80 ka ago. This is significantly later than indicated by the artefact typology (>300 ka) and contrary to the expectation of in situ burial indicated by earlier research in this region. If displacement occurred on other upland sites this finding has important implications for establishing the timing of hominin use of the upland areas which, beyond broad attribution to Lower or Middle Palaeolithic origin, is uncertain and similar doubts apply to the interpretation of the environments that prevailed.     

谈谈如何避免高空观测记录错情

对使用59-701微机数据处理系统以后高空观测记录容易出错的环节进行归纳和分析,并提出相应的解决措施。