Mechanical response of saturated and unsaturated gravels of different sizes in drained triaxial testing     

Alhani  Israa Jamal  Noor  Mohd Jamaludin bin Md  Al-Bared  Mohammed Ali Mohammed  Harahap  Indra Sati Hamonangan  Albadri  Wael Mahmood 《Acta Geotechnica》2020,15(11):3075-3093

Acta Geotechnica - During the construction of pavements, gravelly soil is used as the main material in the base and sub-base layers. Predicting the deformation behaviour of gravelly soil has been...  相似文献   

Finite strain analysis for deformed Neoproterozoic rock associations of the Al Amar fault zone,Eastern Arabian Shield,Saudi Arabia     

Mohammed  Lami Abdel Karim Nouaman  Kassem  Osama Mohamed Kaoud  Al Bassam  Abdel Aziz Mohamed 《Arabian Journal of Geosciences》2020,13(6):1-6

Arabian Journal of Geosciences - In this work, quantitative analysis of coastal zone landform morphology is carried out through the integration of landscape index, remote sensing (RS) and...  相似文献   

Study of X-ray transients with Scanning Sky Monitor (SSM) onboard AstroSat     

M. C. Ramadevi  B. T. Ravishankar  Abhilash R. Sarwade  S. Vaishali  Nirmal Kumar Iyer  Anuj Nandi  V. Girish  Vivek Kumar Agarwal  Blessy Elizabeth Baby  Mohammed Hasan  S. Seetha  Dipankar Bhattacharya 《Journal of Astrophysics and Astronomy》2018,39(1):11

Scanning Sky Monitor (SSM) onboard AstroSat is an X-ray sky monitor in the energy range 2.5–10 keV. SSM scans the sky for X-ray transient sources in this energy range of interest. If an X-ray transient source is detected in outburst by SSM, the information will be provided to the astronomical community for follow-up observations to do a detailed study of the source in various other bands. SSM instrument, since its power-ON in orbit, has observed a number of X-ray sources. This paper discusses observations of few X-ray transients by SSM. The flux reported by SSM for few sources during its Performance Verification phase (PV phase) is studied and the results are discussed.  相似文献   

A morphological evaluation of Chrysaora chinensis of Peninsular Malaysia and distinguishing its populations using geometric morphometrics     

Low Liang Boon  Syazwan Wan Moh  Rizman-Idid Mohammed 《海洋学报(英文版)》2019,38(10):67-74

The morphology of seven specimens of Chrysaora chinensis (Scyphomedusae, Semaestomae) obtained from four sites off the coast of Peninsular Malaysia was examined. Morphological characteristics of C. chinensis that encompasses structures such as the bell, tentacles, oral arms, stomach, manubrium, radial canals and gonads were described in detail. A total of 107 specimens that represented C. chinensis populations of four coastal areas of Peninsular Malaysia (East-Central, East-North, West-Central, and West-North) were also analysed for shape variation using geometric morphometric analysis. Procrustes superimposition, Principal Component Analysis (PCA) and Canonical Variate Analysis (CVA) were applied to the images of gastrovascular pouches of C. chinensis to extract the shape information. Independent contrasts were used for comparisons between shapes. There were no significant differences in shape variation between all the specimens based on the PCA results. However, CVA results showed shape variations between specimens taken from the four areas of Peninsular Malaysia, especially with higher magnitudes of Mahalanobis distances between the east and west coast areas, including between East-Central and East-North, but lower magnitudes were detected between the West-Central and West-North.  相似文献   

Laboratory study of shear strength response of Chlef natural sand: Effect of saturation     

Khayra Merabet  Ismail Benessalah  Mohammed Chemmam 《Marine Georesources & Geotechnology》2020,38(4):461-467

Abstract

The study of the unsaturated soils is a very complex field to which several researches in laboratory and on site are directed these last years. An experimental study aims to quantify the influence of the Skempton coefficient B characterizing the degree of saturation on the behavior of the granular sand to the liquefaction resistance of sand. The study is based on undrained triaxial tests performed on natural Chlef sand carried out at an initial relative density Dr = 50% under a confining pressure of 50, 100 and 200?kPa for Skempton coefficient B?=?10 to 92%. The results of the tests show that an increase of confining pressure leads to an increase of the shear stress of the samples. For the lower value of the degree of saturation results of our findings indicate an increase of the resistance to liquefaction; our results are in good agreement with others observed in several research projects conducted with other sands. The increase of Skempton coefficient B induces an increase of pore water pressure and a decrease of the shear strength. The pore pressure (u) increases with an exponential manner with the increase of the degree of saturation; while the residual shear strength (Rs) decreases with logarithmic manner with the increase of degree of saturation (B).  相似文献   

影响三大洲的北非强沙尘暴动力机制WRF-chem模拟与分析北大核心          下载免费PDF全文

Altayeb Raga  王坚红  Abdoul Aziz Saidou Chaibou  Muhammad Arsha  Mohammed AbdAllah  Birhanu Asmerom Habtemicheal 《气象科学》2022,42(6):769-780

基于WRF-chem模式对北非2018年3月下旬的典型强沙尘暴过程进行模拟,分析了此次强沙尘发生季节、持续时间、局地特征以及传输路径的关键动力系统与动力机制。鉴于起沙是沙尘暴发生的关键点之一,并且起沙主要取决于风力和下垫面沙源性质,本文测试了三种起沙参数化方案的影响,并将模拟结果与卫星MODIS监测及其再分析资料MERRA-2进行了对比,又经系列统计方法检验。结果显示,宏观思路的起沙方案GOCART比AFWA和UoC两种起沙方案更适合此次大尺度强沙尘暴数值模拟(锋面跨度接近60个经度)。综合沙尘暴关键系统的动力机制分析和数值模拟结果显示,强沙尘暴关键系统为深厚的西风槽、沙尘冷锋锋面和锋后的地面高压反气旋。北非中部深厚的西风槽为后倾槽,该系统稳定,造成沙尘暴持续时间长。沙尘暴锋后反气旋中的下沉气流抑制了扬沙向高层扩散,造成低层能见度恶劣。沙尘锋区结合了动力、热动力以及湿热动力不稳定,因此锋区风力大,地面沙尘驱动力强。而西风槽和强大反气旋依托环流形势,提供了沙尘传输到三大洲的长途输送力。  相似文献