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

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...     

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

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.     

Combined use of dimensional analysis and modern experimental design methodologies in hydrodynamics experiments

In this paper, a combined use of dimensional analysis (DA) and modern statistical design of experiment (DOE) methodologies is proposed for a hydrodynamics experiment where there are a large number of variables. While DA is well-known, DOE is still unfamiliar to most ocean engineers although it has been shown to be useful in many engineering and non-engineering applications. To introduce and illustrate the method, a study concerning the thrust of a propeller is considered. Fourteen variables are involved in the problem and after dimensional analysis this reduces to 11 dimensionless parameters. Then, a two-level fractional factorial design was used to screen out parameters that do not significantly contribute to explaining the dependent dimensionless parameter. With the remaining five statistically significant dimensionless parameters, various response surface methodologies (RSM) were used to obtain a functional relationship between the dependent dimensionless thrust coefficient, and the five dimensionless parameters. The final model was found to be of reasonable accuracy when tested against results not used to develop the model. The methodologies presented in the paper can be similarly applied to systems with a large number of control variables to systematically derive approximate mathematical models to predict the responses of the system economically and accurately.     

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

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。