Lead and Zinc Stabilization of Soil Using Sewage Sludge Biochar: Optimization through Response Surface Methodology   总被引：1，自引：0，他引：1       下载免费PDF全文

Azin Fathianpour  Masoud Taheriyoun  Mohsen Soleimani 《洁净——土壤、空气、水》2018,46(5)

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Rayleigh wave separation using high-resolution time-frequency polarization filter     

Mohsen Kazemnia Kakhki  Webe J. Mansur  Franciane C. Peters 《Geophysical Prospecting》2020,68(7):2104-2118

Obtaining geological information from seismic data motivates researchers to innovate and improve seismic wave processing tools. Polarization-based methods have received much attention regarding their ability to discriminate between different phases of the seismic wave based on polarity. Combining the intuitive definition of polarity in the frequency domain (monochromatic waves) with the non-stationary properties provided by time-domain methods, time-frequency approaches are attracting widespread interest because they localize the information extracted from the seismic waves in the joint time and frequency domains. Due to the lack of high-resolution time-frequency maps, the time-frequency polarization approach was not able to resolve specific temporal polarity changes in the seismic signal. The main objective of this study was to devise a robust time-frequency-based polarization filtering method using high-resolution polarization attributes obtained directly from the sparse time-frequency map without using Eigen analysis or analytic signals. The method proposed here utilizes a computationally effective sparsity-based adaptive S-transform to obtain a high-resolution polarization map of an inherently non-stationary seismogram for the entire frequency content of the signal at different times. The superiority of the proposed method over the S-transform method was verified using synthetic and real data sets to calculate the polarization attributes in the time-frequency domain and separate the Rayleigh waves from the seismogram.  相似文献   

Conditional spectrum based ground motion record selection using average spectral acceleration          下载免费PDF全文

Mohsen Kohrangi  Paolo Bazzurro  Dimitrios Vamvatsikos  Andrea Spillatura 《地震工程与结构动力学》2018,47(1):265-265

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A simple two-step method for spatio-temporal design-based balanced sampling     

Ramin?Khavarzadeh  Mohsen?MohammadzadehEmail author  Jorge?Mateu 《Stochastic Environmental Research and Risk Assessment (SERRA)》2018,32(2):457-468

We introduce a two-step method to perform spatio-temporal balanced sampling in a design-based approach. For populations with spatio-temporal trends and with anisotropic effects in the variable of interest, the prediction can be further improved by selecting samples that are well spread over the entire population in space and time. We control the spread of the sample over the population by using the volume of the corresponding three-dimensional Voronoi tessellation. Indeed, spatio-temporal design-based balanced sampling is even more efficient under the presence of a trend and anisotropic effects. We present an intensive simulation study comparing our method to other available methods for spatio-temporal sampling. Finally, we analyze real data by sampling from a population of temperature stations over six European countries.  相似文献   

Pulse-like versus non-pulse-like ground motion records: Spectral shape comparisons and record selection strategies     

Mohsen Kohrangi  Dimitrios Vamvatsikos  Paolo Bazzurro 《地震工程与结构动力学》2019,48(1):46-64

Pulse-like records are well recognized for their potential to impose higher demands on structures when compared with ordinary records. The increased severity of the structural response usually caused by pulse-like records is commonly attributed to the spectral increment around the pulse period. By comparing the building response to sets of spectrally equivalent pulse-like and ordinary records, we show that there are characteristics of pulse-like records beyond the shape of the acceleration response spectrum that affect the results of nonlinear dynamic analysis. Nevertheless, spectral shape together with the ratio of pulse period to the first-mode structural period, T_p/T₁, are confirmed as “sufficient” predictors for deformation and acceleration response metrics in a building, conditioned on the seismic intensity. Furthermore, the average spectral acceleration over a period range, AvgSA, is shown to incorporate to a good proxy for spectral shape, and together with T_p/T₁, form an efficient and sufficient intensity measure for response prediction to pulse-like ground motions. Following this latter route, we propose a record selection scheme that maintains the consistency of T_p with the hazard of the site but uses AvgSA to account for the response sensitivity to spectral shape.  相似文献   

Application of the microtremor measurements to a site effect study          下载免费PDF全文

Sadegh Rezaei  Asskar Janalizadeh Choobbasti 《地震科学（英文版）》2017,30(3):157-164

Earthquake has left much life and property damages. The occurrence of such events necessitates the execution of plans for combating the earthquakes. One of the most important methods for combating earthquakes includes assessing dynamic characteristics of soil and site effect. One of the methods by which one can state dynamic characteristics of the soil of an area is the measurement of microtremors. Microtremors are small-scale vibrations that occur in the ground and have an amplitude range of about0.1–1 microns. Microtremor measurement is fast, applicable, cost-effective. Microtremor measurements were taken at 15 stations in the Babol, north of Iran. Regarding H/V spectral ratio method, peak frequency and amplification factor were calculated for all microtremor stations.According to the analysis, the peak frequency varies from0.67 to 8.10 Hz within the study area. Also, the authors investigated the validity of the results by comparing them with SESAME guidelines and geotechnical conditions of study area. The microtremor analysis results are consistent with SESAME guidelines and geotechnical condition of study area. The results show that the microtremor observations are acceptable methods for assessing dynamic characteristics of soil and site effect in the Babol City.  相似文献   

Mainshock-consistent ground motion record selection for aftershock sequences     

Athanasios N. Papadopoulos  Mohsen Kohrangi  Paolo Bazzurro 《地震工程与结构动力学》2020,49(8):754-771

In recent years, the additional risk posed to the built environment due to aftershock sequences and triggered events has been brought to attention, and several efforts have been directed towards developing fragility functions for structures in damaged conditions. Despite this rise of interest, a rather fundamental component for such tasks, namely that of aftershock ground motion record selection, has remained under-scrutinized. Herein, we propose a pragmatic procedure that can be applied for the selection of mainshock-aftershock ground motion pairs using consistent causal parameters and accounting for the correlation between their spectral accelerations. In addition, a structural analysis strategy that can be employed for the analytical derivation of damage-dependent fragility functions is outlined and presented through a case study. A more conventional back-to-back IDA analysis is also carried out in order to compare the derived damage-dependent fragility functions with the ones obtained with the proposed procedure. The results indicate that record selection remains a crucial factor even when assessing the structural vulnerability of damaged buildings, and should thus be treated cautiously.  相似文献   

The effect of magnetic field morphology on the structure of massive IRDC clumps     

Nahid Bahmani  Mohsen Nejad-Asghar 《Astrophysics and Space Science》2018,363(8):171

Infrared dark clouds (IRDCs) have dense elongated clumps and filaments with the favorable viewing condition of being on the near-side of a bright mid-infrared background. The clumps usually have multiple cores around the center. In this work, we study the effect of magnetic field morphology on the structure of massive IRDC clumps. To achieve this goal, we consider an axisymmetric isothermal oblate IRDC clump, embedded into a constant external magnetic field. We assume a polynomial function for the magnetic field morphology inside the clump. We use the numerical iterative methods to solve the equations: the successive over-relaxation method to find the magnetic and gravitational fluxes, and then the biconjugate gradient method to find the optimized values of mass and current densities. The results show that the IRDC clump will be very elongated along the perpendicular direction of the external magnetic field lines. Also, the assumption of choosing of a polynomial function for the magnetic field morphology leads to the formation of dense regions around the center. The greater the density of the central region, the larger the density of these dense regions and the closer to the center. The presence of these dense regions can lead to the formation of cores at these points.  相似文献   

U-Pb zircon dating,Sr-Nd isotope and petrogenesis of Sarduiyeh granitoid in SE of the UDMA,Iran: implication for the source origin and magmatic evolution     

Asma Nazarinia  Mohsen Arvin  Ruizhong Hu  Chenghai Zhao  Mohammad Poosti 《International Geology Review》2020,62(13-14):1796-1814

ABSTRACT

The Sarduiyeh granitoid (SG) is intruded in the southeastern part of the Dehaj-Sarduiyeh volcano-sedimentary belt in the southeastern end of the Urumieh-Dokhtar Magmatic Arc (UDMA) in Iran. The medium-to-coarse-grained granitoid unit, with granular texture consists mainly of diorite, tonalite, granodiorite and monzogranitic rocks. Mineralogically, these rocks consist mainly of plagioclase, K-feldspar, quartz, biotite and hornblende. The whole rock geochemical analyses indicates that the SG is calc-alkaline, I-type, metaluminous, enriched in large ion lithophile elements (LILE; such as K, Cs, Pb) and depleted in high field strength elements (HFSE; such as Ti, Nb, Ta, Zr). Chondrite normalized plot of SG rare earth elements (REE) show light rare earth element enrichments with (La_N/Yb_N = 2.44–8.68) and flat heavy rare earth element patterns with (Gd_N/Yb_N = 1.02–1.36). The rather high Y (av. 19.35 ppm), low Sr content (av. 293.76 ppm) and low Cr and Ni contents (av. 20.1 and 4.69 ppm, respectively) of the SG demonstrate its normal calc-alkaline and non-adakitic nature, the features of Jebal Barez-type granitoids. The geochemical characteristics and isotopic composition, low I_Sr (0.7046–0.7049) and positive ?^tNd (+3.4 to +4.03) values, of the SG suggest that its parental magma formed as a result of partial melting from metabasic rocks of lower crust in a subduction-related arc setting. Fractionation of an assemblage dominated by plagioclase, K-feldspar, amphibole and magnetite may have been responsible for the evolution of the SG magma. U-Pb zircon geochronology gives an age of 27.95 ± 0.27 Ma for the SG, suggesting that the final collision between the Arabian plate and Central Iranian microcontinent may have happened in the Late Oligocene.  相似文献   

Geochemistry of arc-related mantle peridotites and gabbros from the Chaldoran ophiolite,NW Iran     

Mahleqa Rezaei Bargoshadi  Tian-Nan Yang 《International Geology Review》2020,62(13-14):1724-1750

ABSTRACT

The Neo-Tethys-related Chaldoran ophiolite peridotites in NW Iran are remnants of mantle lithosphere, exhumed tectonically during the Late Cretaceous. Harzburgite is the predominant peridotite type, associated with oceanic lower crust cumulate gabbros occasionally. The ophiolite rocks are unconformably overlain by Late Cretaceous-Paleocene sediments. New whole-rock geochemistry of the variably serpentinized harzburgites shows a depleted nature, exemplified by low Al₂O₃, CaO, TiO₂, V and Y and high Ni, Cr and Mg and also low rare earth element (REE) contents. The harzburgites present LREE enrichment. Positive correlations between some LREEs and high field strength elements (HFSE) suggest enrichment of LREEs by melt re-fertilization processes. Cr-spinels have Cr number of [Cr# = Cr/(Cr + Al) = 0.53–0.67], showing medium to high degree of partial melting (F = ~17-20%). Both whole-rock and mineral chemistry data show a supra-subduction zone setting and progressive depletion along with increase in spinel Cr# (MOR to fore arc). The cumulate gabbros have high MgO and SiO₂, low TiO₂ and Ti/V < 10 and also low chondrite normalized Dy (<8.5). The gabbro samples show enriched LREEs and LILEs and depleted HREEs and HFSEs with respect to MORBs.

Subduction initiation (SI) model in a fore-arc/proto-fore-arc environment is suggested for the upper mantle evolution of the Chaldoran ophiolite. The rocks have experienced depletion in a second melting process at the later stages of SI and compositions were probably modified by extraction of island arc tholeiitic (IAT) and possibly boninitic (BON) melts. The chemostratigraphic progression for ‘subduction initiation rule (SIR)’ is likely traceable in Chaldoran mafic-ultramafic sequence, which corresponds to the most Neo-Tethyan ophiolites and is similar to MOR to supra-subduction zone (SSZ) evolution of most Iranian ‘Inner’ and ‘Outer Zagros’ ophiolitic peridotites.  相似文献