Numerical assessment of tsunami attack on a rubble mound breakwater using OpenFOAM®     

《Applied Ocean Research》2018

A numerical assessment study of tsunami attack on the rubble mound breakwater of Haydarpasa Port, located at the southern entrance of the Istanbul Bosphorus Strait in the Sea of Marmara, Turkey, is carried out in this study using a Volume-Averaged Reynolds-Averaged Navier-Stokes solver, IHFOAM, developed in OpenFOAM^® environment. The numerical model is calibrated with and validated against the data from solitary wave and tsunami overflow experiments representing tsunami attack. Furthermore, attack of a potential tsunami near Haydarpasa Port is simulated to investigate effects of a more realistic tsunami that cannot be generated in a wave flume with the present state of the art technology. Discussions on practical engineering applications of this type of numerical modeling studies are given focusing on pressure distributions around the crown-wall of the rubble mound breakwater, and the forces acting on the single stone located behind the crown-wall at the rear side of the breakwater. Numerical modeling of stability/failure mechanism of the overall cross-section is studied throughout the paper.The present study shows that hydrodynamics along the wave flume and over the breakwater can be simulated properly for both solitary wave and tsunami overflow experiments. Stability of the overall cross-section can only be simulated qualitatively for solitary wave cases; on the other hand, the effect of the time elapsed during tsunami overflow cannot be reflected in the simulations using the present numerical tool. However, the stability of the overall cross-section under tsunami overflow is assessed by evaluating forces acting on the rear side armor unit supporting the crown-wall of the rubble mound breakwater as a practical engineering application in the present paper. Furthermore, two non-dimensional parameters are derived to discuss the stability of this armor unit; and thus, the stability condition of the overall cross-section. Approximate threshold values for these non-dimensional parameters are presented comparing experimental and numerical results as a starting point for engineers in practice. Finally, investigations on the solitary wave and tsunami overflow experiments/simulations are extended to the potential tsunami simulation in the scope of both representation of a realistic tsunami in a wave flume and stability of the rubble mound breakwater.  相似文献   

The Gravity Module Assembly used in airborne full tensor gradiometry surveys     

G.J. Barnes 《Geophysical Prospecting》2019,67(6):1620-1625

In airborne gravity gradiometry, the Gravity Module Assembly is an optional gravimeter unit that is mounted on the same stabilized platform as the Full Tensor Gradiometer. Direct measurements of the gravity field are needed from this device to constrain the long wavelengths when gradient data are integrated mathematically to form high-resolution gravity fields. The Gravity Module Assembly is, however, capable of providing independent gravity data with a specification approaching that expected from a dedicated airborne gravity system. Presented here is an error analysis of data from this instrument collected alongside the Full Tensor Gradiometer during an airborne survey. By having both gradiometry and gravity datasets, comparisons of the information content in these two types of measurement are made.  相似文献   

Impact of three-dimensional attitude variations of an unmanned aerial vehicle magnetometry system on magnetic data quality     

Callum A. Walter  A. Braun  G. Fotopoulos 《Geophysical Prospecting》2019,67(2):465-479

Optically pumped vapour magnetometers have an orientation dependency in measuring the scalar component of the ambient magnetic field which leads to challenges for integration with mobile platforms. Quantifying the three-dimensional attitude variations (yaw, pitch and roll) of an optically pumped vapour magnetometer, while in-flight and suspended underneath a rotary unmanned aerial vehicle, aids in the successful development of reliable, high-resolution unmanned aerial vehicle magnetometry surveys. This study investigates the in-flight three-dimensional attitude characteristics of a GEM Systems Inc. GSMP-35U potassium vapour magnetometer suspended 3 m underneath a Dà-Jiāng Innovations S900 multi-rotor unmanned aerial vehicle. A series of unmanned aerial vehicle-borne attitude surveys quantified the three-dimensional attitude variations that a simulated magnetometer payload experienced while freely (or semi-rigidly) suspended underneath the unmanned aerial vehicle in fair weather. Analysis of the compiled yaw, pitch and roll data resulted in the design of a specialized semi-rigid magnetometer mount, implemented to limit magnetometer rotation about the yaw axis. A subsequent unmanned aerial vehicle-borne magnetic survey applying this specialized mount resulted in more than 99% of gathered GSMP-35U magnetic data being within industry standards. Overall, this study validates that maintaining magnetometer attitude variations within quantified limits (±5° yaw, ±10° pitch and roll) during flight can yield reliable, continuous and high-resolution unmanned aerial vehicle-borne magnetic measurements.  相似文献   

Geophysical mapping of buried faults in parts of Bida Basin,North Central Nigeria          下载免费PDF全文

Musa Olufemi Awoyemi  Ojudoo Darius Ajama  Olayide Sakirudeen Hammed  Augustine Babatunde Arogundade  Sesan Cornelius Falade 《Geophysical Prospecting》2018,66(Z1):40-54

High‐resolution aeromagnetic data over the Bida Basin, North Central Nigeria has been analysed to investigate the possible continuity of Ifewara fault zone, through the Bida Basin, to Zungeru fault zone. Analytic signal magnitude, horizontal gradient magnitude, and Euler deconvolution methods were applied to the aeromagnetic data to delineate the subsurface structures. The results showed that a prominent NNE–SSW trending fault associated with the Ifewara fault zone extends through the study area. Other faults trending in the ENE–WSW, NE–SW, NW–SE, E–W, and WNW–ESE directions were also mapped. Interpreted models revealed the presence of intrusives and a possible mineralised zone within the study area. We therefore concluded that the inferred fault zones within the basin have affinity with the trend of the Ifewara fault zone, which is an indication of possible extension and linkage with Zungeru fault zone through the Bida Basin.  相似文献   

Separation of magnetic anomalies into induced and remanent magnetization contributions     

Jamaledin Baniamerian  Shuang Liu  Xiangyun Hu  Maurizio Fedi  Mahak Singh Chauhan  Mahmoud Ahmed Abbas 《Geophysical Prospecting》2020,68(7):2320-2342

Inversion of magnetic data is complicated by the presence of remanent magnetization, and it provides limited information about the magnetic source because of the insufficiency of data and constraint information. We propose a Fourier domain transformation allowing the separation of magnetic anomalies into the components caused by induced and remanent magnetizations. The approach is based on the hypothesis that each isolated source is homogeneous with a uniform and specific Koenigsberger ratio. The distributions of susceptibility and remanent magnetization are subsequently recovered from the separated anomalies. Anomaly components, susceptibility distribution and distribution of the remanent and total magnetization vectors (direction and intensity) can be achieved through the processing of the anomaly components. The proposed method therefore provides a procedure to test the hypotheses about target source and magnetic field, by verifying these models based on available information or a priori information from geology. We test our methods using synthetic and real data acquired over the Zhangfushan iron-ore deposit and the Yeshan polymetallic deposit in eastern China. All the tests yield favourable results and the obtained models are helpful for the geological interpretation.  相似文献   

一次极端寒潮天气过程等熵位涡分析     

谢瑞青  刘宇迪  朱金双  孟他 《气象科技》2019,47(2):312-321

利用2016年1月1日至31日的FNL资料,对一次极端寒潮天气过程进行了等熵位涡分析。结果表明:高位涡主体由极涡分裂而来,前面低位涡区的阻挡与后侧低位涡大气的北上加强了位涡的经向交换,高位涡空气不断由极地向南输送,使得高位涡主体不断加强维持。高位涡在由北向南移动的同时,也由对流层顶向下输送。此次寒潮过程主要有3股冷空气由上而下发展,位置均在高空急流轴的北侧,最南端的一股下沉气流最旺盛,这是其与高空急流相互作用的结果。强盛的冷空气下沉使得寒潮影响范围触及我国华南地区。随着高位涡的向南向下传输,一方面引起对流层中高层低涡系统迅速发展,当它移到中国东部地区时,东亚大槽迅速加深,使槽后强冷空气迅速向南爆发;另一方面,在高位涡输送的过程中,其后侧有强烈的下沉运动,使得地面冷高压快速发展,导致强寒潮天气的爆发。  相似文献   

Structure of the Potential Vorticity of an Explosive Cyclone over the Eastern Asian Region in Late November 2013     

PANG Huaji  FU Gang  LU Chungu 《中国海洋大学学报(英文版)》2022,21(2):253-263

An explosive extratropical cyclone(EC)over the Eastern Asian region that caused two shipwrecks is analyzed using ERA-Interim reanalysis data from the European Center for Medium-Range Weather Forecasts.Analyses of the evolution of the EC reveal that the positive potential vorticity(PV)at the upper-tropospheric level displays a hook-shaped structure during the mature period of the cyclone.The PV distribution forms a vertically coherent PV structure called a PV tower.The vertical distribution of the PV can induce and strengthen cyclonic circulation from the lower-to upper-levels of troposphere,which is an important deepening mechanism of explosive cyclone.The PV tower occurs approximately ten hours prior to the development of surface occlusion in the cyclone.The evolution of surface fronts closely follows the development of the horizontal upper-tropospheric PV.This tandem development is largely attributed to the ability of the positive upper-tropospheric PV and the PV tower to induce cyclonic circulation simultaneously.The kinematic wrap-up process of cyclonic circulation also accelerates the formation of warm occlusion.A conceptual model of the distributions of positive PV and potential temperature combining the perspectives of dynamic tropopause folding,PV tower,and atmospheric stability,including westward tilting and baroclinicity,is proposed.This model can illustrate the explosive deepening mechanism of ECs.The regions of convective instability and rainfall determined by this model are consistent with those identified from the actual observation.  相似文献   

贵州安顺市PM2.5气象输送条件及贡献源空间分布     

曹青  谷晓平  张翅鹏  陈贞宏  吴哲红 《气象与环境学报》2022,38(2):55-61

利用贵州省安顺市2015—2019年大气污染物资料和气象资料,分析安顺市空气质量特征和主要大气污染物特征,通过TrajStat软件中HYSPLIT模型的后向轨迹模式,结合GDAS气象数据、PM_2.5浓度,分析不同季节输送途径及其污染轨迹,采用潜在源贡献作用和浓度权重轨迹分析方法,分析研究期内所有PM_2.5污染日（PM_2.5日浓度高于75 μg·m^-3）输送轨迹垂直与水平方向分布特征。结果表明: PM_2.5是安顺城区主要大气污染物,冬季输送污染轨迹占比较大,输送方向主要为贵州东北方向、偏南方向; 污染日PM_2.5输送路径以贵州东北方向近距离输送为主,该类轨迹基本分布在880—980 hPa高度; 潜在源高值区主要集中在贵阳整个地区、毕节织金县、黔西市、金沙县等,高贡献值区主要集中在安顺紫云县、镇宁县、毕节织金县、大方县等。  相似文献   

Origin,discovery, exploration and development status and prospect of global natural hydrogen under the background of “carbon neutrality”     

《China Geology》2022,5(4):722-733

Global energy structure is experiencing the third transition from fossil energy to non-fossil energy, to solve future energy problems, cope with climate change, and achieve net-zero emissions targets by 2050. Hydrogen is considered to be the most potential clean energy in this century under the background of carbon neutrality. At present, the industrial methods for producing hydrogen are mainly by steam-hydrocarbon (such as coal and natural gas) reforming and by electrolysis of water, while the exploration and development of natural hydrogen had just started. According to this literature review: (1) Natural hydrogen can be divided into three categories, including free hydrogen, hydrogen in inclusions and dissolved hydrogen; (2) natural hydrogen could be mainly from abiotic origins such as by deep-seated hydrogen generation, water-rock reaction or water radiolysis; (3) natural hydrogen is widely distributed and presents great potential, and the potential natural hydrogen sources excluding deep source of hydrogen is about (254±91)×10⁹ m³/a according to a latest estimate; (4) at present, natural hydrogen has been mined in Mali, and the exploration and development of natural hydrogen has also been carried out in Australia, Brazil, the United States and some European countries, to find many favorable areas and test some technical methods for natural hydrogen exploration. Natural hydrogen is expected to be an important part of hydrogen energy production in the future energy pattern. Based on a thorough literature review, this study introduced the origin, classification, and global discovery of natural hydrogen, as well as summarized the current global status and discussed the possibility of natural hydrogen exploration and development, aiming to provide reference for the future natural hydrogen exploration and development.©2022 China Geology Editorial Office.  相似文献   

Structural Setting and Kinematic Analysis of the Halaban Region,Eastern Arabian Shield,Saudi Arabia     

Osama M. KASSEM  Yousef A. ALAMRI  Faisal K. ZAIDI  Abdel Aziz M. AL BASSAM  Mansour H. AL-HASHIM 《《地质学报》英文版》2021,95(3):750-760

The vorticity analysis technique was applied to measure the different lithological units,such as schist,metagranite and metavolcano-sedimentary rocks,which are present in the Halaban region.This work aims to interpret the relationship between the different lithologies and the tectonic setting,in order to elucidate the nature of kinematic analysis in the Halaban region.The kinematic analyses were applied to feldspar porphyroclasts,quartz and hornblende for twentysix samples.The kinematic vorticity number (W_m) for deformed rocks in the study area ranged from～0.6 to 0.9.The direction of the long axes for finite strain data (X axes) revealed a WNW trend with shallow dipping.The direction of the short axes for finite strain data (Z axes) were represented by vertical with associated horizontal foliation.The results of the kinematic vorticity and strain analyses are characterized by simple shear with different degrees of deformation in the Halaban region.Furthermore,our finite strain data shows no significant volume change during deformation.The subhorizontal foliation was synchronized with thrusting and deformation.Furthermore,throughout the overlying nappes,the same attitudes of tectonic contacts are observable,the nappes in the orogens being formed from simple shear deformation.  相似文献