An efficient method for single-facility location and path-connecting problems in a cell map

This article presents an efficient method for simultaneously finding both the Weber cell and optimal connective paths in a grid. As numerous barriers of arbitrary shape and weighted regions are distributed in the cell map of this research, the problem scenario is similar to working out a real-life facility location selection and path-routing problems in a geographical map. In this study, the Weber problem of finding a single-facility location from an accumulation cost table is generated by a grid wave propagation method (higher-geometry maze router). After finding the Weber point (cell), optimal connective paths with minimum total weighted cost are backtracked between the Weber location cell and the demand cells. This new computation algorithm with linear time and space complexity can be integrated as a spatial analytical function within GIS.     

Sensitivity study of pulsed neutron-gamma saturation monitoring at the Altmark site in the context of CO2 storage

The injection of CO₂ into depleted natural gas reservoirs has been proposed as a promising new technology for combining enhanced gas recovery and geological storage of CO₂. During the injection, application of suitable techniques for monitoring of the induced changes in the subsurface is required. Observing the movement and the changes in saturation of the fluids contained in the reservoir and the confining strata is among the primary aims here. It is shown that under conditions similar to the Altmark site, Germany, pulsed neutron-gamma logging can be applied with limitations. The pulsed neutron-gamma method can be applied for detection and quantification of changes in brine saturation and water content, whereas changes in the gas composition are below the detection limit. A method to account for the effects of salt precipitation resulting from evaporation of residual brine is presented.     

Sequence architecture and carbonate platform configuration (Late Cenomanian–Santonian), Sinai, Egypt

Abstract Relative sea‐level changes on the mixed carbonate–siliciclastic platform of Sinai are manifested in shifts of distinct facies belts (deep‐water facies, high‐energy subtidal, shallow subtidal, lagoon, shallow shoreface siliciclastics, supratidal) and are interpreted in terms of sequence stratigraphy. Eight sedimentary sequences are recognized for the Upper Cenomanian to Santonian. Their correlation along a north–south transect reveals distinct changes in lithofacies and progradation/retrogradation patterns within the individual systems tracts. The number and stratigraphy of the sequence boundaries of Sinai correlate well with those from adjacent areas. Patterns of increased subsidence are documented for the Central Sinai Basin since the Late Cenomanian by increased thickness of the stratal packages (post‐CeSin 7 HST, post‐TuSin 1 LST and HST, post‐TuSin 2 LST) and are balanced by varying accumulation rates. Based on new sedimentological and biostratigraphic data, large‐scale palaeogeographic maps and cross‐sections show the: (1) temporal and spatial evolution of the Central Sinai Basin, e.g. its latest Cenomanian initial formation, Lower Turonian deep‐water facies, Middle Turonian to Coniacian synsedimentary subsidence; (2) drowning of the Cenomanian platform coinciding with the latest Cenomanian to Early Turonian relative sea‐level rise; (3) re‐establishment of the platform in Middle–Late Turonian times; and (4) a Coniacian basin and swell morphology.     

Less ice on the Baltic reduces the extent of hypoxic bottom waters and sedimentary phosphorus release

A significant relation was established between the maximum extent of sea ice covering the Baltic Sea and the hypoxic area in the deeper parts of the Baltic Proper, with a lag of 2 years: for the period 1970–2000, less ice was correlated with a smaller anoxic area. At the same time, maximum ice extent is subject to a long-term climate-related decline, due to higher air temperatures and an increased frequency of westerly winds. Together, this suggests that the hypoxic area will decrease in the coming decades. Internal sedimentary phosphorus-loading is closely related to the hypoxic area and hence would decrease as well. Wind strength variability did not have a significant additive effect to the variance in hypoxic area already explained by sea ice extent. The observed lag is in agreement with the order of magnitude of estimated residence times in the shallower sub-basins feeding the Baltic Proper, where ice extent varies most.     

Quantitative high resolution cathodoluminescence spectroscopy of diagenetic and hydrothermal dolomites

A combination of high resolution cathodoluminescence-spectroscopy (HRS-CL=high resolution spectroscopy of cathodoluminescence emission) with spatial resolving trace element analyses (PIXE=proton induced X-ray emission) is used to establish a method for the quantitative determination of the Mn-content of diagenetic and hydrothermal dolomites using the measurements of peak areas of Mn-activated CL emission bands. This method takes into account the overlap of the CL broad bands of Mn²⁺ in the Mg- and the Ca-lattice-position of dolomite. There is a linear correlation between the peak areas and Mn concentration up to approx. 1000–1500 ppm. Thus, CL spectroscopy allows a determination of Mn concentrations below the abilities of PIXE (10–15 ppm) to less than 1 ppm by extrapolation of this linear relation.

Up to an Fe-content of approx. 2000 ppm, no quenching effect of Fe on this linear relationship occurs. However, Fe-contents above 2000 ppm result in a decrease of Mn-induced luminescence. Even at Fe-concentration >25,000 ppm spectroscopy reveals that Mn-activated CL of dolomite is not entirely extinguished.     

Modelling rating curves using remotely sensed LiDAR data

Accurate stream discharge measurements are important for many hydrological studies. In remote locations, however, it is often difficult to obtain stream flow information because of the difficulty in making the discharge measurements necessary to define stage‐discharge relationships (rating curves). This study investigates the feasibility of defining rating curves by using a fluid mechanics‐based model constrained with topographic data from an airborne LiDAR scanning. The study was carried out for an 8m‐wide channel in the boreal landscape of northern Sweden. LiDAR data were used to define channel geometry above a low flow water surface along the 90‐m surveyed reach. The channel topography below the water surface was estimated using the simple assumption of a flat streambed. The roughness for the modelled reach was back calculated from a single measurment of discharge. The topographic and roughness information was then used to model a rating curve. To isolate the potential influence of the flat bed assumption, a ‘hybrid model’ rating curve was developed on the basis of data combined from the LiDAR scan and a detailed ground survey. Whereas this hybrid model rating curve was in agreement with the direct measurements of discharge, the LiDAR model rating curve was equally in agreement with the medium and high flow measurements based on confidence intervals calculated from the direct measurements. The discrepancy between the LiDAR model rating curve and the low flow measurements was likely due to reduced roughness associated with unresolved submerged bed topography. Scanning during periods of low flow can help minimize this deficiency. These results suggest that combined ground surveys and LiDAR scans or multifrequency LiDAR scans that see ‘below’ the water surface (bathymetric LiDAR) could be useful in generating data needed to run such a fluid mechanics‐based model. This opens a realm of possibility to remotely sense and monitor stream flows in channels in remote locations. Copyright © 2012 John Wiley & Sons, Ltd.     

新疆天山西部三个云杉上树线树轮最大密度年表的研制、相关性及其气候信号分析

针对新疆天山西部伊犁、博尔塔拉蒙古自治区州三大山体北坡云杉上树线树木年轮最大密度资料,采用区域曲线、负指数曲线、样条函数三种不同生长去趋势方法,研制树轮最大密度年表,分析不同采点和树轮去趋势方法对树轮最大密度年表在不同频域的相关性及气候信号的影响发现:①三个采点间的最大树轮密度变化,在高频变化方面最为相似,低频变化存在着较大差异;②天山西部山脉北坡上树线的树轮最大密度年表对年表研制的三种不同去趋势方法不敏感,而采点间的距离和是否位于同一气候区是影响上树线树轮最大密度年表间相关性的重要因子;③天山西部山脉北坡上树线的树轮最大密度年表对当年的温度具有显著的相关性,年降水量越多的山区,其上树线最大密度年表对温度的相关性越好,且显著相关平均温度涉及的月数也不断增多.