A general solution for groundwater flow in an estuarine's leaky aquifer system after considering aquifer anisotropy

This paper presents an analytical model for describing the tidal effects in a two‐dimensional leaky confined aquifer system in an estuarine delta where ocean and river meet. This system has an unconfined aquifer on top and a confined aquifer on the bottom with an aquitard in between the two. The unconfined and confined aquifers interact with each other through leakage. It was assumed that the aquitard storage was negligible and that the leakage was linearly proportional to the head difference between the unconfined and confined aquifers. This model's solution was based on the separation of variables method. Two existing solutions that deal with the head fluctuation in one‐dimensional or two‐dimensional leaky confined aquifers are shown as special cases in the present solution. Based on this new solution, the dynamic effect of the water table's fluctuations can be clearly explored, as well as the influence of leakage on the behaviour of fluctuations in groundwater levels in the leaky aquifer system. Copyright © 2015 John Wiley & Sons, Ltd.     

Ancient mantle lithosphere beneath the Khanka massif in the Russian Far East: in situ Re–Os evidence

The Os‐isotope compositions of sulphides in mantle xenoliths hosted by Late Miocene alkali basalts from the Sviyaginsky volcano, Russian Far East, reveal the presence of Archaean–Proterozoic subcontinental lithospheric mantle beneath the Khanka massif. Their T_MA and T_RD model ages reveal similar peaks at 1.1 and 0.8 Ga suggesting later thermotectonic events in the subcontinental lithospheric mantle, whereas T_RD model ages range back to 2.8 ± 0.5 (2σ) Ga. The events recognized in the subcontinental lithospheric mantle are consistent with those recorded in the crust of the Khanka massif. The sulphide Os‐isotope data show that the subcontinental lithospheric mantle beneath the Khanka massif had formed at least by the Mesoproterozoic, and was subsequently metasomatized by juvenile crustal‐growth events related to the evolution of the Altaids. The Khanka massif is further proposed to have tectonic affinity to the Siberia Craton and should originate from it accordingly.     

低温无固相钻井液配方优选及经济性评价

为解决高原冻土和天然气水合物勘探过程中钻进和取心问题,选择了NaCl作为抗冻剂,抗盐共聚物GTQ和水解聚丙烯酰胺PHP作为主要聚合物试剂,采用正交试验法,在常温下优选出了9组配方,经过低温测试,确定了在 -15 ℃可用的钻井液配方Z1（20%NaCl+0.1%PHP+1.2%GTQ+1%KHm）和Z2（25%NaCl+0.15%PHP+1.0%GTQ+1%KHm）,其主要性能指标分别为：AV值46.5、47.5 mPa·s,PV值34、35 mPa·s,YP值12.8、12.8 Pa,FLAPI值6.8、7.6 mL/30 min。经成本核算,2种配方具有比较好的经济性,可以满足高原冻土层钻进要求。     

Comparison of SPT-N-based analysis methods in evaluation of liquefaction potential during the 1999 Chi-chi earthquake in Taiwan

SPT-N-based methods have been adopted for liquefaction assessment of soils during earthquakes for decades. However, there has not been a consistent way of assessing the accuracy and applicability of these methods. The Chi-chi earthquake of 1999, which has been the most serious ground shaking in Taiwan within the century, caused extensive liquefactions in mid-west alluvial deposits of the island. This paper assesses the prediction accuracy of several SPT-N-based methods using liquefaction and non-liquefaction incidents observed during the earthquake. A sensitivity study on commonly adopted parameters shows that the SPT blow count and peak ground acceleration are most sensitive in computing liquefaction potential. By comparing the error in predicting liquefaction and non-liquefaction incidents, this study concludes that Tokimatsu and Yoshimi’s method is more accurate than the other methods. However, the differences between prediction errors of various methods are minimal, indicating all of the methods examined are applicable for the 1999 earthquake in Taiwan.     

Reflection of typhoon morakot �� the challenge of compound disaster simulation

Climate change has altered locally single-type disasters to large-scale compound disasters because of increasing intensity and frequency of extreme rainfall events. The compound disasters can combine small-scale floods, debris flows, shallow landslides, deep-seated landslides, and landslide lakes into a large-scale single disaster event. Although simulation models and evaluation tools are available for single-type disasters, no single model is well developed for compound disasters due to the difficulty of handling the interrelationship between two successive single-type disasters. This study proposes a structure for linking available single-type simulation models to evaluate compound disasters and provides a useful tool of decision making for warning and planning of disaster reduction.     

First results from the arcminute cosmology bolometer array receiver

We review the first science results from the Arcminute Cosmology Bolometer Array Receiver (ACBAR); a multi-frequency millimeter-wave receiver optimized for observations of the Cosmic Microwave Background (CMB) and the Sunyaev–Zel’dovich (SZ) effect in clusters of galaxies. ACBAR was installed on the 2 m Viper telescope at the South Pole in January 2001 and the results presented here incorporate data through July 2002. We present the power spectrum of the CMB at 150 GHz over the range ℓ=150–3000 measured by ACBAR as well as estimates for the values of the cosmological parameters within the context of ΛCDM models. We find that the inclusion of Ω_Λ greatly improves the fit to the power spectrum. We also observe a slight excess of small-scale anisotropy at 150 GHz; if interpreted as power from the SZ effect of unresolved clusters, the measured signal is consistent with CBI and BIMA within the context of the SZ power spectrum models tested.     

南、北盘江流域枯水期水化学特征及离子来源分析

为进一步了解珠江上游南、北盘江流域水化学现状,对其枯水期36个河水样品进行水化学特征分析,结果表明:枯水期河水pH值在7.85~8.75之间,呈弱碱性,TDS均值为358 mg·L-1。河水中阴离子组成以HCO3-、SO42-为主,当量浓度占比均值达到65%与26%,阳离子中Ca2+和Mg2+是绝对的优势离子,当量浓度占比均值分别为65%和24%。与丰水期相关研究对比分析发现Ca2+、Mg2+、Na+、SO42-、HCO3-、Cl-的枯水期浓度普遍高于丰水期,K+、NO3-丰、枯水期浓度变化不大。Piper图、岩性端元分析以及离子浓度比值分析表明,研究区水化学主要受碳酸和硫酸共同参与下的碳酸盐岩风化控制。南、北盘江流域都受到农业施用的钾肥和氮肥的影响,此外,北盘江主要受到煤炭开采以及燃煤工业的影响,南盘江主要受到源头及上游河段化工企业废水和沿途市县的生活废水的影响。与前人数据对比发现,15年间人为活动对流域水化学的影响加剧。      

An alternative depth-integrated formulation for granular avalanches over temporally varying topography with small curvature

An alternative formulation is proposed for deriving depth-integrated equations for gravity-driven granular avalanches over a non-trivial topography with small curvature. The coordinate system of Bouchut and Westdickenberg (2004 Bouchut, F and Westdickenberg, M. 2004. Gravity driven shallow water models for arbitrary topography. Commun. Math. Sci., 2: 359–389. [Crossref] , [Google Scholar]) is combined with the unified coordinate (UC) method, so that it can evolve in accordance with the entrainment–deposition processes at the basal surface. The resultant mass and momentum equations are formulated as a conservation system of the Cartesian components of the conservative physical variables. The motion of the flows is driven by the basal topography-induced pressure, pressure gradient, and resisted by the basal friction. The best benefit of this formulation is that it greatly simplifies the computation of the varying coordinate orientations. The features and advantages of this formulation are illustrated by the sliding-mass examples where we simulate the motion of a finite mass of granular material sliding down an inclined chute, running through a transition zone, and being deposited onto a horizontal plane.     

Spatial interpolation using MLP–RBFN hybrid networks

It is easy for a multi-layered perception (MLP) to fit a stratified spatial interpolation pattern whose form is close to open surface; while it is easy for a radial basis function network (RBFN) to fit a pocket (radial) spatial interpolation pattern whose form is close to closed surface. However, in the real world, the spatial interpolation pattern may consist of stratified and pocket patterns. Neither MLP nor RBFN can fit the pattern easily. To combine their advantages to fit the complex hybrid spatial interpolation patterns, in this article we propose a novel neural network, MLP–RBFN hybrid network (MRHN), whose hidden layer contains sigmoid and Gaussian units at the same time. Although there are two kinds of processing units in MRHN, in this study we used the principle of minimizing the error sum of squares to derive the supervised learning rules for all the network parameters. This research took rainfall distribution in Taiwan as a case study. The results show that (1) the prediction error of the testing dataset outside the training dataset demonstrated that MRHN was the most accurate among the three networks, RBFN was the next best, and MLP was the worst; (2) the MLP model seriously underestimated the values of high observed rainfall; (3) over-learning may be a serious shortcoming of using RBFN in spatial interpolation applications; (4) MRHN may have better generalization learning capacity than RBFN in spatial interpolation applications.     

Locating, monitoring, and characterizing typhoon-linduced landslides with real-time seismic signals

Landslides induced by typhoon Morakot during its passage across Taiwan on 7–9 Aug 2009 claimed more than 700 lives and caused heavy economic loss. Unlike earthquake monitoring, precise locations of landslides could not be determined in near-real time because their seismic phases are difficult to identify. Here, we show that large, damaging landslide events are characterized seismically by a distinct waveform pattern of frequent intermixes of P and S waves over a time window of several tens of seconds. The predominant frequency band during these time windows ranges from 0.5 to 5?Hz. The high-frequency content is clearly deficient relative to that of local earthquakes by about one to two orders. We also demonstrate that large landslide events can be located and monitored with algorithms specifically designed for real-time seismic applications. This near-real-time monitoring capability would be particularly useful for emergency responders and government organizations to coordinate effective relief-and-rescue operations.