A Numerical Study of Effects of Valley-Weathering and Valley-Shape-Ratio on the Ground Motion Characteristics

A study of combined effects of valley-weathering and valley-shaperatio on the ground motion characteristics and associated differential ground motion (DGM) is documented in this paper. In order to properly quantify the weathering effects, a forth-order-accurate staggered-grid viscoelastic time-domain finite-difference program has been used for the simulation of SH-wave responses. Simulated results revealed that the defocusing caused by valley is frequency-independent in contrast to the ridge-focusing. A decrease of average spectral amplification (ASA) with an increase of shape-ratio of the non-weathered triangular and elliptical valleys was obtained. Overall, the amplification and de-amplification pattern was larger in case of triangular valleys as compared to the elliptical valleys. It can be concluded that the dwelling within or near the topcorners of weathered valleys may suffer more damage as compared to their surroundings. A weathered triangular valley with large shape-ratio may cause unexpected damage very near its top-corners since both the ASA and DGM are largest.     

Improvement in predictability of waves over the Indian Ocean

Accurate prediction of ocean surface waves is a challenging task with many associated difficulties. Availability of good quality wind and wave information from satellite platforms inspired the scientific community to assimilate such data in various spectral wave models for enhancing the accuracy of prediction. Over the Indian Ocean, which is the region of interest for the present study, wave heights in extreme situation can go up to 12–14 m, thereby increasing the probability of coastal hazards. This region is further governed by the southern ocean swells that propagate thousands of kilometers. These are, in general, not well captured by the spectral wave models. Therefore, assimilation of altimeter data in open ocean wave model WAM has been attempted with the aim of enhancing the quality of prediction of significant wave height. Further, simulated wave spectra have been assimilated in a coastal wave model SWAN. This assimilation has been found to significantly improve the prediction of the height of wind waves as well as swell waves. V. Bhatt and S. Surendran are former students of Meteorology and Oceanography Group, Space Applications Centre, ISRO, Ahmedabad.     

Design and Development of Onsite Biofilter Unit for Effective Remediation of Contaminants from Wastewater

Agricultural biomass is proven ecofriendly and effective adsorbent for the remediation of contaminants from wastewater. Here, rice husk biochar (600 °C) prepared by a one-step pyrolysis method is used for the remediation of different contaminants in real samples. An onsite biofilter unit is fabricated with parallel trenches of different layers of coconut coir and biochar and is used as a biofiltration unit. The efficiency of the designed unit is assessed for the removal of different contaminants in pilot-scale experiments. Results show that removal efficiency varies from metal to metal and ranges from 5.52% to 90.76% using the biofilter unit. Fourier-transform infrared spectroscopy, scanning electron microscopy with energy dispersive X-ray analysis, carbon, hydrogen, nitrogen, and Brunauer–Emmett–Teller analysis before and after the adsorption represent the changes in the morphology and surface functionalization of the biochar. Results indicate that the designed biofilter unit could also be used as a promising agent for the remediation of pharmaceutical and other emerging contaminants from wastewater.     

Elevational Dependence of Air Temperature Variability and Trends in British Columbia's Cariboo Mountains, 1950–2010

Pristine mountain environments are more sensitive to climate change than other land surfaces. Climatic variations in mountainous terrain are still poorly understood. Previous studies revealed inconsistent findings on the elevational dependence of warming in the mountains. In this study, the trends and elevational dependence of air temperature in the Cariboo Mountains Region (CMR) of British Columbia are explored using a surface air temperature dataset with a spatial resolution of five arc minutes over the 1950–2010 period. A Mann-Kendall test is performed for evaluation of trends and their significance. In recent decades the CMR has been warming at a faster rate than regional and global warming. The minimum air temperature trend shows significant amplified warming at higher elevations. The snow–albedo feedback and changes in cloud cover over the CMR may possibly be the major physical mechanisms responsible for these trends. The implications of such changes on the endangered mountain caribou and water resources of the area are also discussed.     

Experiments on integral length scale control in atmospheric boundary layer wind tunnel

Accurate predictions of turbulent characteristics in the atmospheric boundary layer (ABL) depends on understanding the effects of surface roughness on the spatial distribution of velocity, turbulence intensity, and turbulence length scales. Simulation of the ABL characteristics have been performed in a short test section length wind tunnel to determine the appropriate length scale factor for modeling, which ensures correct aeroelastic behavior of structural models for non-aerodynamic applications. The ABL characteristics have been simulated by using various configurations of passive devices such as vortex generators, air barriers, and slot in the test section floor which was extended into the contraction cone. Mean velocity and velocity fluctuations have been measured using a hot-wire anemometry system. Mean velocity, turbulence intensity, turbulence scale, and power spectral density of velocity fluctuations have been obtained from the experiments for various configuration of the passive devices. It is shown that the integral length scale factor can be controlled using various combinations of the passive devices.     

Analysis of the Saharan dust regional transport

Summary The Balkan Peninsula is situated in the impact zone of Saharan dust storms. The case of Saharan dust transport to Belgrade in the period of 14–17 April 1994 is analyzed using the Eta model for synoptic and meso scale processes. Air back trajectories are calculated at six model levels from 434 up to 5129m with horizontal grid resolutions of 1°×1° and 10×10. Following cyclonic circulation the dust was picked up from North Africa, and transported over Mediterranean. Simultaneously, according to the analysis of the three lowest trajectories, transport of trace metals from Macedonia and southern Serbia by the Koshava wind might be dominant in the observed episode. Turbulent flow enhanced the coagulation process of initially clean dust particles with particles containing Pb and Cd. The coagulation and scavenging processes below and in clouds increased deposition rates of Pb and Cd in Belgrade in the course of wet removal, and consequently trough resuspension processes. Dry deposition samples contained characteristic particles up to 30µm in diameter with Fe content of 11 to 15 atomic% and significant ratio Si/Fe of 3 to 5, determined for selected single particles by the SEM/EDX method. Following dry and wet deposition of Cd and Pb, a residual effect of dustfall is noticed throughout the vegetational period.     

A Review of the Bentong-Raub Suture vis-à-vis New Insight of the Tectonic Evolution of Malay Peninsula,South East Asia

Genesis of the so‐called Bentong‐Raub Suture of Malay Peninsula does not fit to the model of subduction‐related collision. It has evolved from transpression tectonics resulting closure and exhumation of the inland basin which underwent extensive back‐arc extension during Triassic. Crust having similar thickness (average ～35 km) below entire Malay Peninsula nagate collision of two separate continental blocks rather supports single continental block that collided with South China continental block during Permo‐Triassic. Westward subduction of intervening sea (Proto South China Sea) below Malay Peninsula resulted in widespread I‐ and S‐Type granitization and volcanism in the back‐arc basins during Triassic. Extensive occurrence of Permo‐Triassic Pahang volcanics of predominantly rhyolitic tuff suggest its derivation from back‐arc extension. Back‐arc extension, basin development and sedimentation of the central belt of the peninsula continued until Cretaceous. A‐Type granite of metaluminous to peraluminous character indicates their emplacement in an intraplate tectonic setting. Malay Peninsula suffered an anticlockwise rotation due to the rifting of Luconia–Dangerous Grounds from the east Asia in the Late Cretaceous–Early Tertiary. Extensive ductile and brittle deformation including crustal segmentation, pull‐apart fracturing and faulting occurred during the closure and exhumation of the basins developed in the peninsula during Late Cretaceous–Early Tertiary. Crustal shortening in the central belt of the peninsula has been accomodated through strike‐slip displacement, shearing and uplift.     

Signature of the 27-day variation in hemispheric sunspot activity and asymmetry during 2010-2015

In the present work,we study the time evolution,significance of the N-S asymmetry excesses presented as a function of the solar cycle and prominent rotational p...     

Viscous fluid universe filled with stiff fluid in general relativity

We have investigated two stiff-fluid models in which the material distribution is that of viscous fluid. In the first model, the coefficient of shear viscosity is assumed to be constant while in the second model the coefficient of shear viscosity is proportional to the rate of expansion in the model. The paper also discusses some physical and geometrical aspects of the model. The behaviour of the model in absence of viscosity is also discussed.     

On the stable stratification of the nocturnal lower troposphere inferred from lidar observations over Pune,India

The nocturnal structure of the lower troposphere is studied using aerosol profile data (50–2800 m AGL) obtained with a bistatic, continuous wave, Argon ion lidar system during October 1986–September 1989 at Pune (18°32 N, 73°51 E, 559m AMSL), India. The top of the nocturnal groundbased inversion is taken as the height above ground where the negative vertical gradient in aerosol concentration first reaches a maximum. During the post-sunset period over this station, this height is as low as 160m and frequently lies around 550m. Greater heights are observed in pre-monsoon months and smaller ones during the southwest monsoon season. Positive vertical gradients in aerosol concentration, indicative of stable/elevated layers, appear frequently around 750m. Temporal variations of aerosol concentration gradients in two adjacent air layers, 920–1000m and 100–1100m, provide evidence that stability increases downward in the early night hours.