Evaluation of Subsurface Structure at Soultz Hot Dry Rock Site by the AE Reflection Method in Time-frequency Domain

—?Because the Soultz Hot Dry Rock (HDR) site, France, is to be expanded to a scientific pilot plant of greater depth, measurement of the deep area below the predeveloped artificial reservoir is gaining importance. In this paper, we present estimates of deep subsurface structure at the Soultz HDR site, obtained by a reflection method using acoustic emission (AE) signals, that is, induced seismicity, as the wave source. First, we briefly describe the AE reflection method in the time-frequency domain with wavelet transform. Then we show estimates of the subsurface structure by using 101 high-energy AE events observed in 1993. We compare and discuss the results obtained, using the AE reflection method in two wells with other independent borehole observations. Furthermore, we present the results of an investigation of the frequency dependence of reflectors identified by hodogram linearity as a possible means of further characterizing detected structures.     

Advanced approach for degradation of recalcitrant by nanophotocatalysis using nanocomposites and their future perspectives

Industrial effluents containing persistent pollutants play a significant role in environmental pollution. Classical techniques such as chlorination, coagulation, ion flotation, membrane process and sedimentation that have been used to decontaminate polluted water are incapable of efficient degradation due to the generation of secondary pollutants. Photocatalysis, an advanced oxidation process in which the photoreaction is accelerated by the irradiation of catalyst, has shown efficient degradation of recalcitrant in water system. Usage of nanoparticles as homogenous photocatalyst has become prevalent due to their improved properties such as large surface-to-volume ratio, controlled uniform particle size and its composition which enhances the degradation rate. The recombination of holes and electron pair which is considered to be the limitation in homogenous system can be overcome by nanocomposites or heterogeneous photocatalysts. This system decreases the rate of recombination, leading to effective degradation of individual pollutants because of their enhanced physicochemical and structural properties. In recent years, heterogeneous nanophotocatalytic processes employing titanium dioxide (TiO₂) and zinc oxide (ZnO) composites have gained immense research interest as an effective wastewater treatment method because of its efficacy in decomposing and mineralizing the hazardous organic and inorganic pollutants utilizing the UV and visible photons. This paper reviews about the process, synthesis and parameters influencing photocatalytic reaction and their kinetics with much emphasize on types of nanoparticles and nanocomposites and its application in wastewater treatment.     

Vegetation damage assessment due to Hudhud cyclone based on NDVI using Landsat-8 satellite imagery

Developing nations are abandoned against tropical cyclones because of climatic changeability; the atmosphere is probably going to expand the recurrence and extent of some outrageous climate and calamity occasions. Urban areas and towns arranged along the coastline front belt in Visakhapatnam region experienced serious harm because of Hudhud cyclone, which happened on October 12, 2014. The fundamental motivation behind this exploration was to distinguish the vegetation damage in Visakhapatnam and neighbouring towns. In this analysis, Landsat-8 satellite datasets procured prior and then afterward the cyclone have been utilized; image processing techniques have been completed to evaluate the progressions of pre- and post-disaster condition. Vegetation index strategy was utilized to assess the damage to vegetation. Arrangement results and land utilize land cover change investigation demonstrate that 13.25% of agriculture Kharif and 31.1% of vegetation was damaged. Normalized difference vegetation index (NDVI) maps were produced for the previously, then after the cyclone circumstance, and vegetation biomass damage was evaluated in Visakhapatnam and Bhimunipatanam. General loss of vegetation in both the spots was 30.67 and 43.37 km². The result of this review can be utilized by decision makers for the post-disaster support for rebuilding of influenced regions.     

A note on disturbances in a certain type of visco-elastic solid deformed by a magnetic field

Summary The present note is an attempt to study the propagation of disturbances in a semiinfinite visco-elastic rod which is of three-parameter type, and which is subjected to a static magnetic field.     

Diurnal variation in the initiation of rainfall over the Indian subcontinent during two different monsoon seasons of 2008 and 2009

In the present study, the diurnal variations in the time of initiation of rainfall, during two contrasting monsoon seasons of 2008 (below normal) and 2009 (normal) over the Indian subcontinent and surrounding oceanic areas has been analyzed. Harmonic analysis was used to detect the spatial variation of the diurnal cycle of the time of initiation of rainfall, as obtained at half-hourly intervals from the Kalpana 1 satellite. In general, the diurnal cycle in the time of initiation is strongest in regions where convective clouds are predominant, while it is weaker in regions where the clouds are predominantly stratiform with long-lived medium to high cloud cover. In the interior of the subcontinent, the time of maximum mainly occurred in the afternoon to evening hours, with a distinct southeast to northwest gradation. Substantial spatial variations were detected in the diurnal patterns between a normal and below normal monsoon years. Spatially, rainfall is initiated later in 2009 compared to 2008 over most of the interior of the Indian subcontinent. The most distinct difference was observed over the core monsoon region in central India, where the diurnal patterns were stronger in 2009 compared to 2008. On the other hand, over the oceans surrounding the Indian subcontinent, the initiation times are generally earlier in 2009.     

Optimization of Nowcast Software WDSS-II for operational application over the Indian region

Nowcasting in the India Meteorological Department (IMD) is being provided for T + 0 to T + 2 h, using the Warning Decision Support System (WDSS-II) software. Prior to operational nowcasting over the Indian region, the parameters of the nowcast algorithm tool of the software were optimized, and accuracy was evaluated for various weather systems over Delhi. This optimization is demonstrated in this study with reference to three weather systems over Delhi, with each case representing one of three typical types of cloud systems over the region. These are—(a) convective lines associated with winter and early pre-monsoon weather systems, (b) deep convective cells that form in the pre-monsoon (April–June) and post-monsoon season (October–November) and (c) wide convective echoes that form during the monsoon season. The efficacy of the algorithm was assessed on a frame-by-frame basis as well as holistically for entire convective episodes. The important findings of the frame-by-frame study are (1) the inability of the inbuilt growth-decay algorithm to capture the evolution of storm cells, (2) setting of the threshold of detection of storms and tracking storms and (3) number of scales through which storms should be tracked. The holistic capabilities of the nowcast algorithm were tested for entire convective episodes using Model Evaluation Tools software. The results indicate that the advection algorithm tends to move the convective areas faster than observed at all time scales. Hence the multi-scale segmentation approach (over the two-scale approach) increases the smoothening of the output, at the cost of decreased nowcast skill. The inter-event comparison indicates that the low-intensity convective line zones, which are characteristic of winter and early pre-monsoon weather systems, have the most rapid temporal change in the overall area under convection. This leads to larger area errors during nowcasting of these systems. On the other hand, pre-monsoon systems comprised mostly isolated cells that reach great heights and move very fast, but do not have much horizontal area growth. The error in the nowcasting of these systems is mostly in respect of location error, as well as error in forecast of the intensity of the cells. The overall error in nowcasting is least for the monsoon systems over the Delhi region.     

Oxidative–reductive photodecomposition of perfluorooctanoic acid in water

This article aims to elucidate on usefulness of vacuum ultraviolet (VUV) for photoreductive degradation of perfluorooctanoic acid (PFOA), a representative perfluorinated compound (PFC), in water for the first time. Bench-scale tests were conducted on oxidative and reductive (with aquated electron: e _aq ^? ) mineralization of PFOA using low-pressure UV (LPUV) lamps and potassium iodide. Unlike with 254 nm wavelength (UVC), the reductive mineralization with VUV was very inefficient compared to the corresponding oxidative mineralization. The inefficiency is attributed to low reactivity of e _aq ^? with PFOA and its fluorinated products than that of 185 nm photons. Direct VUV photolysis of PFOA and its products in reductive reaction conditions was not apparent due to a very big difference in reactivity of 185 and 254 nm photons with iodide. The results demonstrated that highly energetic VUV photons are not suitable for photoreductive degradations of PFCs involving e _aq ^? , but they can be best used for oxidative degradations. These findings should serve as an important reference on VUV usage to decompose refractory micropollutants.     

Pseudo-dynamic methods for seismic passive earth pressure behind a cantilever retaining wall with inclined backfill

The designing of retaining walls requires the complete knowledge of earth pressure distribution. Under earthquake conditions the design needs special attention to reduce the devastating effect, but under seismic conditions, the available literature mostly uses the pseudo-static analytical solution as an approximate to the real dynamic nature of the complex problem. This paper shows a detailed study on the seismic passive earth thrust behind a cantilever retaining wall with inclined backfill surface by pseudo-dynamic analysis. A planar failure surface has been considered. The effect of variation of parameters such as soil friction angle, wall friction angle and back fill inclination have been explored. A complete analysis shows that the time dependent non-linear behaviour of the pressure distribution obtained in the present method results in more realistic design values of earth pressures under earthquake conditions. Results are provided in tabular and graphical non-dimensional form and compared thoroughly with the existing values in the literature.     

Quasi-spherical collapse with cosmological constant

The junction conditions between static and non-static space–times are studied for analysing gravitational collapse in the presence of a cosmological constant. We have discussed about the apparent horizon and their physical significance. We also show the effect of cosmological constant in the collapse and it has been shown that cosmological constant slows down the collapse of matter.     

Sound velocity and density of liquid Ni68S32 under pressure using ultrasonic and X-ray absorption with tomography methods

A new experimental setup for simultaneous P-wave velocity (V_P) and density (ρ) measurements for liquid alloys is developed using ultrasonic and X-ray absorption methods combined with X-ray tomography at high pressures and high temperatures. The new setup allows us to directly determine adiabatic bulk moduli (K_S) and to discuss the correlation between the V_P and ρ of the liquid sample. We measured V_P and ρ of liquid Ni₆₈S₃₂ up to 5.6 GPa and 1045 K using this technique. The effect of pressure on the V_P and ρ values of liquid Ni₆₈S₃₂ is similar to that of liquid Fe₅₇S₄₃. (Both compositions correspond to near-eutectic ones.) The obtained K_S values are well fitted to the finite strain equation with a $K_{{\text{S}}_0}$ value (K_S at ambient pressure) of 31.1 GPa and a dK_S/dP value of 8.44. The measured V_P was found to increase linearly with increasing ρ, as approximated by the relationship: V_P [m/s] = 1.29 ρ [kg/m³] – 5726, suggesting that liquid Ni–S follows an empirical linear relationship, Birch's law. The dV_P/dρ slope is similar between Ni₆₈S₃₂ and Fe₅₇S₄₃ liquids, while the V_P–ρ plot of liquid Ni–S is markedly different from that of liquid Fe–S, which indicates that the effect of Ni on Birch's law is important for understanding the V_P–ρ relation of planetary and Moon's molten cores.