Seismic hazard disaggregation in performance‐based earthquake engineering: occurrence or exceedance?

Seismic hazard disaggregation is commonly used as an aid in ground‐motion selection for the seismic response analysis of structures. This short communication investigates two different approaches to disaggregation related to the exceedance and occurrence of a particular intensity. The impact the different approaches might have on a subsequent structural analysis at a given intensity is explored through the calculation of conditional spectra. It is found that the exceedance approach results in conditional spectra that will be conservative when used as targets for ground‐motion selection. It is however argued that the use of the occurrence disaggregation is more consistent with the objectives of seismic response analyses in the context of performance‐based earthquake engineering. Copyright © 2015 John Wiley & Sons, Ltd.     

Developing service-oriented applications in a grid environment

The Open-source Project for a Network Data Access Protocol (OPeNDAP) software framework has evolved over the last 10 years to become a robust, high performance, service oriented architecture for the access and transport of scientific data from a broad variety of disciplines, over the Internet. Starting with version 4.0 of the server release, Hyrax, has at its core, the Back-End Server (BES). The BES offers ease of programming, extensibility and reliability allowing added functionality especially related to high-performance data Grids, that goes beyond its original goal of distributed data access. We present the fundamentals of the BES server as a component based architecture, as well as our experiences using the BES to distribute data processing in Grid-oriented intensive parallel computational tasks.     

Dark side of the planet: hidden dimensions of urban agglomeration

ABSTRACT

This intervention probes the hidden, political dimensions of planetary urbanization. Drawing on political theory, it approaches its analysis through the analytic of ‘the political,’ the dimension in which antagonism performs a constitutive function in the social order. In doing so the intervention throws into relief the ways in which group-based differentiation, conflict, and exclusion establish the conditions of possibility for ongoing transformations of urban agglomeration. It then develops a case for further exploring intersections of the political and capitalist agglomeration to generate new knowledge about current mutations in urban economies of space.     

A GIS-based glacier inventory for the Antarctic Peninsula and the South Shetland Islands —A first case study on King George Island

The aim of the international project “Global Land Ice Measurements from Space (GLIMS)” headed by the US Geological Survey is to establish a world wide glacier inventory based on satellite imagery. This data set will form a first digital baseline study for future glacier monitoring. The presented GIS-based glacier inventory for King George Island is a case study for the area of the Antarctic Peninsula. In the database of the glacier inventory topographic information, specific glaciological parameters as well as metadata will be included. The topographic data consists of drainage basin limits, basin areas, altitudinal ranges, perimeters and mean lengths. Glaciological data sets should comprise information on glacier retreat in different periods, glacier velocities, ice thickness and bedrock topography as well as derived parameters. Modelled and measured mass balance parameters could be included as additional data layers. In particular, these metadata records must comprise background information on data accuracy and data sources and should be compatible with a future data model for the King George Island GIS (KGIS). Three examples illustrate that the GLIMS database will not only contain information valuable for glaciological applications, but also other environmental studies on the island will benefit from this standardised remote sensing data sets. Therefore, a very close link between the data models of KGIS and GLIMS has to be established to enable these synergisms. Finally, better access to historic aerial photography would enable a continuous record of glacier retreat from the beginning of the 1950's onward.     

Design and application of a direct-push vadose zone gravel permeameter

A borehole permeameter is well suited for testing saturated hydraulic conductivity (K(sat)) at specific depths in the vadose zone. Most applications of the method involve fine-grained soils that allow hand auguring of test holes and require a small water reservoir to maintain a constant head. In non-cohesive gravels, hand-dug test holes are difficult to excavate, holes are prone to collapse, and large volumes of water are necessary to maintain a constant head for the duration of the test. For coarse alluvial gravels, a direct-push steel permeameter was designed to place a slotted pipe at a specific sampling depth. Measurements can be made at successive depths at the same location. A 3790 L (1000 gallons) trailer-mounted water tank maintained a constant head in the permeameter. Head in the portable tank was measured with a pressure transducer and flow was calculated based on a volumetric rating curve. A U.S. Bureau of Reclamation analytical method was utilized to calculate K(sat). Measurements with the permeameter at a field site were similar to those reported from falling-head tests.     

How good is good? Human values and Europe's proposed Marine Strategy Directive

The adoption of the proposed European Marine Strategy Directive is an opportunity for a comprehensive policy for protecting, improving and sustainably using Europe's environmentally degraded seas. It calls for an ecosystem-based approach to management where humans are regarded as a key system component. Although the proposed wording has been the subject of fierce debate, the central policy goal remains achieving "Good Environmental Status". The interpretation of "good" is key to implementation and relates to human values and worldviews. We demonstrate how these vary widely across Europe. Solution of fundamental considerations such as the assignation of reference states, the balance between precautionary and evidence-based action, the degree of subsidiarity, and conservation strategies including marine protected areas, will ultimately depend upon public understanding, involvement in and support for the Directive. The social element, critical to effective adaptive management, requires greater attention within the context of a regional seas geographical framework.     

Influence of seepage undercutting on the stability of root‐reinforced streambanks

Several mechanisms contribute to streambank failure including fluvial toe undercutting, reduced soil shear strength by increased soil pore‐water pressure, and seepage erosion. Recent research has suggested that seepage erosion of noncohesive soil layers undercutting the banks may play an equivalent role in streambank failure to increased soil pore‐water pressure. However, this past research has primarily been limited to laboratory studies of non‐vegetated banks. The objective of this research was to utilize the Bank Stability and Toe Erosion Model (BSTEM) in order to determine the importance of seepage undercutting relative to bank shear strength, bank angle, soil pore‐water pressure, and root reinforcement. The BSTEM simulated two streambanks: Little Topashaw Creek and Goodwin Creek in northern Mississippi. Simulations included three bank angles (70° to 90°), four pore‐water pressure distributions (unsaturated, two partially saturated cases, and fully saturated), six distances of undercutting (0 to 40 cm), and 13 different vegetation conditions (root cohesions from 0·0 to 15·0 kPa). A relative sensitivity analysis suggested that BSTEM was approximately three to four times more sensitive to water table position than root cohesion or depth of seepage undercutting. Seepage undercutting becomes a prominent bank failure mechanism on unsaturated to partially saturated streambanks with root reinforcement, even with undercutting distances as small as 20 cm. Consideration of seepage undercutting is less important under conditions of partially to fully saturated soil pore‐water conditions. The distance at which instability by undercutting became equivalent to instability by increased soil pore‐water pressure decreased as root reinforcement increased, with values typically ranging between 20 and 40 cm at Little Topashaw Creek and between 20 and 55 cm at Goodwin Creek. This research depicts the baseline conditions at which seepage undercutting of vegetated streambanks needs to be considered for bank stability analyses. Copyright © 2008 John Wiley & Sons, Ltd.     

福建南部沿海的江豚

在闽南厦门至漳浦沿海获22只江豚,根据背部棘状小结节的数量与分布,可明显分为两个亚种,即指名亚种(N.P.Phocaenoides,81%)和北方亚种(N.P.Sunameri,19%),表明本海域是几个亚种的混栖地带,分析了这些江豚的外部形态和种群结构,测定了脂肪层及各内脏的重量.