Harvesting ambient geospatial information from social media feeds   总被引：5，自引：0，他引：5  

Anthony Stefanidis  Andrew Crooks  Jacek Radzikowski 《GeoJournal》2013,78(2):319-338

Social media generated from many individuals is playing a greater role in our daily lives and provides a unique opportunity to gain valuable insight on information flow and social networking within a society. Through data collection and analysis of its content, it supports a greater mapping and understanding of the evolving human landscape. The information disseminated through such media represents a deviation from volunteered geography, in the sense that it is not geographic information per se. Nevertheless, the message often has geographic footprints, for example, in the form of locations from where the tweets originate, or references in their content to geographic entities. We argue that such data conveys ambient geospatial information, capturing for example, people’s references to locations that represent momentary social hotspots. In this paper we address a framework to harvest such ambient geospatial information, and resulting hybrid capabilities to analyze it to support situational awareness as it relates to human activities. We argue that this emergence of ambient geospatial analysis represents a second step in the evolution of geospatial data availability, following on the heels of volunteered geographical information.  相似文献   

Structural and Tectonic Framework of the Qilian Shan-Nan Shan Thrust belt,Northeastern Tibetan Plateau     

Andrew ZUZA  Robin REITH  An YIN  DONG Shuwen  LIU Wencan  ZHANG Yuxiu  WU Chen 《《地质学报》英文版》2013,87(Z1):1-3

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Implementation/optimization of moving least squares response surfaces for approximation of hurricane/storm surge and wave responses     

Alexandros A. Taflanidis  Gaofeng Jia  Andrew B. Kennedy  Jane M. Smith 《Natural Hazards》2013,66(2):955-983

One of the important recent advances in the field of hurricane/storm modelling has been the development of high-fidelity numerical simulation models for reliable and accurate prediction of wave and surge responses. The computational cost associated with these models has simultaneously created an incentive for researchers to investigate surrogate modelling (i.e. metamodeling) and interpolation/regression methodologies to efficiently approximate hurricane/storm responses exploiting existing databases of high-fidelity simulations. Moving least squares (MLS) response surfaces were recently proposed as such an approximation methodology, providing the ability to efficiently describe different responses of interest (such as surge and wave heights) in a large coastal region that may involve thousands of points for which the hurricane impact needs to be estimated. This paper discusses further implementation details and focuses on optimization characteristics of this surrogate modelling approach. The approximation of different response characteristics is considered, and special attention is given to predicting the storm surge for inland locations, for which the possibility of the location remaining dry needs to be additionally addressed. The optimal selection of the basis functions for the response surface and of the parameters of the MLS character of the approximation is discussed in detail, and the impact of the number of high-fidelity simulations informing the surrogate model is also investigated. Different normalizations of the response as well as choices for the objective function for the optimization problem are considered, and their impact on the accuracy of the resultant (under these choices) surrogate model is examined. Details for implementation of the methodology for efficient coastal risk assessment are reviewed, and the influence in the analysis of the model prediction error introduced through the surrogate modelling is discussed. A case study is provided, utilizing a recently developed database of high-fidelity simulations for the Hawaiian Islands.  相似文献   

Bombs behaving badly: unexpected trajectories and cooling of volcanic projectiles     

Lo?c Vanderkluysen  Andrew J. L. Harris  Karim Kelfoun  Costanza Bonadonna  Maurizio Ripepe 《Bulletin of Volcanology》2012,74(8):1849-1858

We collected thermal infrared video of two explosive eruptions at Stromboli in June 2008 and manually traced the trajectories of 95 particles launched during two eruptions. We found that 10–15?% of the analyzed trajectories deviated from predicted curves due to collisions, causing one particle to travel horizontally more than twice as far as expected. Furthermore, we observed an oscillatory cooling behavior for the airborne pyroclasts, with a median period of 0.46?s. Measured cooling was typically much faster than model-predicted cooling with discrepancies of up to 40?% between measured cooling and theoretical modeling. We interpret the measured cooling curves as resulting from the spinning and twisting and tearing of particles during travel: the periodic re-exposing of the hotter core of the pyroclasts to the atmosphere may cause the observed oscillations, and the spinning may accelerate cooling by enhancing convective heat transfer. Current volcanic trajectory and cooling models do not account for projectile collisions, spinning, or tearing and can thus severely underestimate the maximum landing distance and cooling rates of large pyroclasts.  相似文献   

Methods for reactive oxygen species (ROS) detection in aqueous environments     

Justina M. Burns  William J. Cooper  John L. Ferry  D. Whitney King  Brian P. DiMento  Kristopher McNeill  Christopher J. Miller  William L. Miller  Barrie M. Peake  Steven A. Rusak  Andrew L. Rose  T. David Waite 《Aquatic Sciences - Research Across Boundaries》2012,74(4):683-734

This review summarizes direct and indirect analytical methods for the detection and quantification of the reactive oxygen species (ROS): ¹O₂, O ₂ ^·? /HOO·, H₂O₂, HO·, and CO ₃ ^·? in aqueous solution. Each section briefly describes the chemical properties of a specific ROS followed by a table (organized alphabetically by detection method, i.e., absorbance, chemiluminescence, etc.) summarizing the nature of the observable (associated analytical signal) for each method, limit of detection, application notes, and reaction of the probe molecule with the particular ROS.  相似文献   

Comparative Evaluation of Single‐Well LNAPL Tracer Testing at Five Sites          下载免费PDF全文

Andrew Pennington  Jonathon Smith  Brad Koons  Craig E. Divine 《Ground Water Monitoring & Remediation》2016,36(2):45-58

Light nonaqueous phase liquid (LNAPL) tracer testing is a technique used to directly measure LNAPL flow in situ and evaluate LNAPL mobility and recoverability. The test method consists of adding a fluorescent oil‐soluble tracer to LNAPL within a well, isolating small volumes of LNAPL with known tracer concentrations for use as in‐well calibration standards, and measuring the rate of tracer concentration decline in the well over time. The test measures LNAPL flux through the well, which is directly related to LNAPL mobility and recoverability in the surrounding formation. Test results for a total of 29 wells at five sites are presented. Results from LNAPL tracer testing were comparable to results obtained through other methods, and the method offers a time‐averaged result measured over a relatively long period, in ambient conditions, and reflects the influences of heterogeneity and hydraulic changes. In some cases, tracer concentration decline followed unexpected patterns, and these data have led to a better understanding of test assumptions, mechanisms influencing tracer distribution, and options to improve test execution and data interpretation. Method improvements developed over the course of the field studies included refinement of pre‐test screening of LNAPL fluorescence and improvements to measurement equipment. Overall, the field studies confirmed the technical validity and usefulness of the LNAPL tracing technique to support LNAPL mobility and recoverability assessments.  相似文献   

Satellite imaging coral reef resilience at regional scale. A case-study from Saudi Arabia     

Rowlands G  Purkis S  Riegl B  Metsamaa L  Bruckner A  Renaud P 《Marine pollution bulletin》2012,64(6):1222-1237

We propose a framework for spatially estimating a proxy for coral reef resilience using remote sensing. Data spanning large areas of coral reef habitat were obtained using the commercial QuickBird satellite, and freely available imagery (NASA, Google Earth). Principles of coral reef ecology, field observation, and remote observations, were combined to devise mapped indices. These capture important and accessible components of coral reef resilience. Indices are divided between factors known to stress corals, and factors incorporating properties of the reef landscape that resist stress or promote coral growth. The first-basis for a remote sensed resilience index (RSRI), an estimate of expected reef resilience, is proposed. Developed for the Red Sea, the framework of our analysis is flexible and with minimal adaptation, could be extended to other reef regions. We aim to stimulate discussion as to use of remote sensing to do more than simply deliver habitat maps of coral reefs.  相似文献   

Rapid evaluation and damage assessment of instrumented highway bridges     

Virginia Mosquera  Andrew W. Smyth  Raimondo Betti 《地震工程与结构动力学》2012,41(4):755-774

This study focuses on the use of strong motion data recorded during earthquakes and aftershocks to provide a preliminary assessment of the structural integrity and possible damage in bridges. A system identification technique is used to determine dynamical characteristics and high‐fidelity first‐order linear models of a bridge from low level earthquake excitations. A finite element model is developed and updated using a genetic algorithm optimization scheme to match the frequencies identified and to simulate data from a damaging earthquake for the bridge. Here, two criteria are used to determine the state of the structure. The first criteria uses the error between the data recorded or simulated by the calibrated nonlinear finite element model and the data predicted by the linear model. The second criteria compares relative displacements of the structure with displacement thresholds identified using a pushover analysis. The use of this technique can provide an almost immediate, yet reliable, assessment of the structural health of an instrumented bridge after a seismic event. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Editorial 2012     

Stuart N. Lane 《地球表面变化过程与地形》2012,37(1):1-2

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Seeking good peer review in geomorphology     

Stuart N. Lane 《地球表面变化过程与地形》2012,37(1):3-8

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