http://www.sciencedirect.com/science/article/pii/S167498711100137X

This study presents promising variants of genetic programming (GP),namely linear genetic programming (LGP) and multi expression programming (MEP) to evaluate the liquefaction resistance of sandy soils....     

Large dead-ice depressions in flat-topped eskers: evidence of a Preboreal jökulhlaup in the Stockholm area, Sweden

Sedimentological investigations in Pålamalm, one of the few elongated, flat-topped, raised glaciofluvial deposits of the Stockholm area, show that the deposit was formed in a subglacial tunnel environment during the early Preboreal. The study provides evidence for dynamic links between the morphology of a subglacial conduit, the regional subglacial discharge, and the regional ice-sheet dynamics. The general morphology of the deposit and the lateral esker displacement are parts of a regional pattern.The development and interrelations of the eight distinguished lithofacies at Pålamalm provides evidence for the triggering mechanism responsible for the deposition of this 3-km-long glaciofluvial deposit. Strongly deformed gravels occur close to large dead-ice structures. The occurrence of another elongated and flat-topped glaciofluvial deposit, Jordbromalm, further to the east suggests a sudden regional subglacial outburst (jökulhlaup) in the area. The sudden, intensive enhancement of water discharge in Pålamalm is probably due to the same outburst. This is assumed to have caused the ice roof of the conduit to collapse. The high meltwater-pressure gradient caused the diameter of the conduit to increase rapidly. In addition, the subglacial tunnel took a new route because the original course became blocked by large ice blocks that had fallen from the roof.The steep flanks of the deposit, the presence of large dead-ice depressions along the central part of the deposit and the appearance of two different tunnel-core facies in the main cross-section of the Pålamalm deposit support the hypothesis of a course change after the jökulhlaup. A probable late-glacial crustal rebound in response to the rapid deglaciation in the area may have been the triggering mechanism for the abrupt discharge of the subglacial lake.     

The typology of the American metropolis: monocentricity,polycentricity, or generalized dispersion?

Although the spatial structure of employment in large US metropolitan regions is a well-researched topic, few studies focus on medium-sized and small US metropolitan regions. Consequently, there is no overall typology relating small-to-medium urban form to employment distribution. We address this gap by investigating the spatial structure of employment in 356 metropolitan regions. We conceptualize six typologies based on three categories that have overlapping properties: “monocentricity,” “polycentricity,” and “generalized dispersion.” The study has three main findings. First, the three types of urban form that we identify as “hybrid” outnumber the three “pure” types by almost four to one. Second, job dispersion is a dominant characteristic in almost 70% of all metropolitan statistical areas (MSAs) (including the hybrid types), and polycentricity (56.7% of MSAs) is somewhat more common than monocentricity. Third, there is a strong relationship between population size and density. The population of medium-sized metropolitan areas is generally more dispersed than that of small and large metropolitan areas. Polycentricy emerges mostly in large metropolitan regions, while monocentrity is found in both small and large metropolitan regions.     

Assessing the IRNSS L5-signal in combination with GPS,Galileo, and QZSS L5/E5a-signals for positioning and navigation

The Indian Regional Navigation Satellite System (IRNSS), which is being developed for positioning services in and around India, is the latest addition to the global family of satellite-based navigation systems. As IRNSS only shares the L5-frequency with GPS, the European Galileo, and the Japanese Quasi-Zenith Satellite System (QZSS), it has at least at present a limited interoperability with the existing systems. Noting that the L5-frequency capability is under development even for GPS, this contribution assesses the interoperability of the IRNSS L5-signal with the GPS, Galileo, and QZSS L5/E5a-signals for positioning and navigation using real data collected in Perth, Australia. First, the noise characteristic of the IRNSS L5-signal and its comparison with that of the GPS, Galileo, and QZSS L1/E1- and L5/E5a-signals is presented. Then, the L5-observables of combined systems (formed from IRNSS, GPS, Galileo, and QZSS) are assessed for real-time kinematic positioning using the standard LAMBDA method and for instantaneous attitude determination using the constrained LAMBDA method. The results show that the IRNSS L5-signal has comparable noise characteristics as that of the other L5/E5a-signals. For single-frequency carrier phase-based positioning and navigation, the results show better ambiguity resolution performance of L5/E5a-only processing than that of L1/E1-only processing.     

Assessment of a spatial multi-criteria evaluation to site selection underground dams in the Alborz Province,Iran

Most part of Iran is arid and semi-arid; thus in most parts of the region, groundwater is the only source of water. This research presents a method based on a spatial multi-criterion evaluation (SMCE) for designing possible sites of underground dams and ranks them according to their suitability. The method was tested for siting underground dams in the Alborz Province, Iran. At first, screening algorithm was applied using exclusionary criteria, and thirty-one potential areas were recognized in the study area. In the next step, a suitable gorge or valley was recognized using the combination of basic maps and extensive field surveys (long axis of tank level) in each potential area. Subsequently, the analytical hierarchy process was used as a powerful tool for decision-making in the SMCE in order to evaluate different criteria for underground dam sites. SMCE techniques were then applied to combine the criteria, and obtain a suitability map in the study area. These sites were then compared and ranked according to their main criteria such as water, storage, axis and socio-economics. All these criteria were assessed through geographical information system modelling. This method shows passable results and could be used for site selection of underground dams in other regions of Iran.