Dietary pattern recognition on Twitter: a case example of before,during, and after four natural disasters     

Turner-McGrievy  Gabrielle  Karami  Amir  Monroe  Courtney  Brandt  Heather M. 《Natural Hazards》2020,103(1):1035-1049

Natural Hazards - Little is known about what foods/beverages (F&B) are common during natural disasters. The goal of this study was to track high-frequency F&B mentions during four...  相似文献   

Estimating wave crest distributions using the method of L-moments     

Amir H. Izadparast  John M. Niedzwecki   《Applied Ocean Research》2009,31(1):37-43

The design of fixed or floating offshore structures requires accurate information of the met-ocean data at the intended offshore site. In the design process it is recognized that this environmental data is modified in the near-field by the interaction with the particular geometrical configuration of the offshore structure. This transformation of the incident wave field around and beneath an offshore structure presents a challenge for ocean engineers when specifying the wave gap elevation to avoid impact loads on the underside of the deck and inundation of the topsides. Thus, the accurate estimation of the wave crest distributions from measurements at various locations near and under the offshore structure during model test studies is essential. A semi-empirical approach is presented herein that builds upon the findings of previous studies and introduces the Method of L-moments. A three parameter model for a wave crest probability distribution function is presented and explicit relationships between the parameters of the distribution and its’ first three L-Moments are established. Furthermore, three narrow-band models from earlier research studies are reviewed and compared with the new model. Wave measurements from a mini-TLP model test program are used as the basis for comparison of the four distributions. The root-mean-square error is used as a metric to quantify the overall fit of the data and its accuracy in the high end tail of the data. The L-Moment model is shown to be more robust in representing the data in both the far-field and beneath the deck of the mini-TLP where the wave field demonstrates increased non-linear behavior.  相似文献   

Spatial Modeling of Geotechnical Information Using GML   总被引：1，自引：0，他引：1  

Jean-Pierre Bardet  Amir Zand 《Transactions in GIS》2009,13(1):125-165

Geotechnical data characterizes the geometry and physical properties of soil deposits, which are determined from field observations, in-situ and laboratory tests, and engineering analyses. Until now, geotechnical information was mainly described and exchanged as relational data, which occasionally included spatial characteristics. Hereafter, the spatial features of geotechnical data are investigated by invoking the geotechnical data model of the Association of Geotechnical and Geoenvironmental Specialists (AGS), which is widely used in the United Kingdom to exchange geotechnical data in engineering practice. The basic geometric objects in AGS geotechnical data are first identified. These geometric objects are mapped to basic geometric features of the Geography Markup Language (GML). AGS data can therefore be fully rendered using GML-conformant schemas, which make geotechnical data readily importable into GML-aware applications. The data can be also imported to mainstream GIS applications using Extensible Markup Language (XML) transformations. This article demonstrates the rendition of AGS data format to a GML-conformant schema and illustrates the implementation of the new format through a few geotechnical examples.  相似文献   

Drilling-induced remanent magnetization in basalt drill cores     

Haraldur Audunsson  Shaul Levi 《Geophysical Journal International》1989,98(3):613-622

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Prediction and validation of traffic vibration reduction due to cement column stabilization     

Andrew T. Peplow  Amir M. Kaynia   《Soil Dynamics and Earthquake Engineering》2007,27(8):793-802

The transmission and reduction of vibrations in the far-field of the surface of the ground due to a surface load is investigated theoretically and validated with given field measurement data. The performance of a given stabilization column, located directly underneath the load, at a number of receiver positions is studied and measured in terms of insertion loss. A numerical model is presented, which enables the wave-field in the region of the column to be determined, based on an integral equation formulation of the problem which is solved using a boundary element approach. It is shown that the column has a beneficial effect at low frequencies especially in certain frequency bandwidths and is validated with field data. However, when the Rayleigh wavelength becomes short compared with the depth and width of the column adverse effects occur at some frequencies which are also observed in the far-field. Various depths of columns and material properties of the surrounding soil medium are studied and results presented so that some preliminary physical conclusions may be derived.  相似文献   

Vertical eddy diffusivity estimations in Swan river estuary   总被引：1，自引：0，他引：1  

Amir Etemad-Shahidi  Jorg Imberger 《Dynamics of Atmospheres and Oceans》2005,39(3-4):175-187

A field experiment is described in which diapycnal diffusivity is estimated by direct and indirect methods in Swan river estuary, Perth, Western Australia. The microstructure profiles were collected in a narrow and straight part of this estuary using a portable flux profiler (PFP). The profiles were segmented into stationary parts and the rate of vertical eddy diffusivity was estimated for the segments within the pycnocline. The direct measurement showed that instantaneous flux could be positive or negative with a low net rate of vertical eddy diffusivity for mass of about 6.5 × 10⁻⁸ m² s⁻¹. All the indirect methods overestimated this rate. However, within the indirect methods, the method of Osborn yielded the poorest estimate while the method of Osborn and Cox gave the closest estimate.  相似文献   

Non-stationary return levels of CMIP5 multi-model temperature extremes     

Linyin Cheng  Thomas J. Phillips  Amir AghaKouchak 《Climate Dynamics》2015,44(11-12):2947-2963

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Axisymmetric interaction of a rigid disc with a transversely isotropic half‐space     

Amir Aabbas Katebi  Ali Khojasteh  Mohammad Rahimian  Ronald Y. S. Pak 《国际地质力学数值与分析法杂志》2010,34(12):1211-1236

A theoretical formulation is presented for the determination of the interaction of a vertically loaded disc embedded in a transversely isotropic half‐space. By means of a complete representation using a displacement potential, it is shown that the governing equations of motion for this class of problems can be uncoupled into a fourth‐order partial differential equation. With the aid of Hankel transforms, a relaxed treatment of the mixed‐boundary value problem is formulated as dual integral equations, which, in turn, are reduced to a Fredholm equation of the second kind. In addition to furnishing a unified view of existing solutions for zero and infinite embedments, the present treatment reveals a severe boundary‐layer phenomenon, which is apt to be of interest to this class of problems in general. The present solutions are analytically in exact agreement with the existing solutions for a half‐space with isotropic material properties. To confirm the accuracy of the numerical evaluation of the integrals involved, numerical results are included for cases of different degrees of the material anisotropy and compared with existing solutions. Further numerical examples are also presented to elucidate the influence of the degree of the material anisotropy on the response. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

Deriving snow‐cover depletion curves for different spatial scales from remote sensing and snow telemetry data          下载免费PDF全文

Steven R. Fassnacht  Graham A. Sexstone  Amir H. Kashipazha  Juan Ignacio López‐Moreno  Michael F. Jasinski  Stephanie K. Kampf  Benjamin C. Von Thaden 《水文研究》2016,30(11):1708-1717

During the melting of a snowpack, snow water equivalent (SWE) can be correlated to snow‐covered area (SCA) once snow‐free areas appear, which is when SCA begins to decrease below 100%. This amount of SWE is called the threshold SWE. Daily SWE data from snow telemetry stations were related to SCA derived from moderate‐resolution imaging spectroradiometer images to produce snow‐cover depletion curves. The snow depletion curves were created for an 80 000 km² domain across southern Wyoming and northern Colorado encompassing 54 snow telemetry stations. Eight yearly snow depletion curves were compared, and it is shown that the slope of each is a function of the amount of snow received. Snow‐cover depletion curves were also derived for all the individual stations, for which the threshold SWE could be estimated from peak SWE and the topography around each station. A station's peak SWE was much more important than the main topographic variables that included location, elevation, slope, and modelled clear sky solar radiation. The threshold SWE mostly illustrated inter‐annual consistency. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

Origin and kinematics of a basin-scale,non-polygonal,layer-bound normal fault system in the Levant Basin,eastern Mediterranean     

Amir Joffe  Christopher A.-L. Jackson  Josh Steinberg  Rebecca E. Bell  Yizhaq Makovsky 《Basin Research》2023,35(2):662-691

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