Seismic interference of two nearby horizontal strip anchors in layered soil

In the present analysis, an attempt is made to explore the seismic response of two nearby horizontal strip anchors embedded in non-homogenous c-? soil deposit at different depths. The analysis is performed by using two-dimensional finite-element software PLAXIS 2D. Each anchor carries equal static safe-working load without violating the ultimate uplift capacity under static condition. The soil is assumed to obey the Mohr?CCoulomb failure criterion. The behavior of single isolated anchor subjected to an earthquake loading is determined first to study the interference effect between two anchors. The horizontal acceleration response obtained from the Loma Prieta Gilroy Earthquake (1989) is considered as the input excitation in the analysis. A parametric study is performed by varying the clear spacing (S) between the anchors at different embedment ratios (??). The magnitude of vertical displacement, shear stress, and shear strain developed at different locations of the failure domain is determined for different clear spacings between the anchors.     

Geometrical mechanism of inverse grading in grain-flow deposits: An experimental revelation

The grain-flow has so far been defined with reference to the distinctive sediment-support mechanism, the dispersive pressure. The role of sediment-support mechanism, however, is required in a multiphase flow to prevent the gravitational settling of the particles through the driving medium during the flow. In a single-phase flow of non-cohesive grains no such secondary mechanism is required to counteract the gravitational pull, the driving force of the flow. So the definition of grain-flow needs a critical revision. This, in turn, involves proper understanding of the grain-flow mechanism, so that the relation between the process and the product can be properly established. The most distinctive feature often demonstrated by a grain-flow deposit is the particle size segregation, which leads to the development of inverse grading. The available explanations for this phenomenon find theoretical constraints. In the present study an attempt was made to understand the mechanism of single-phase non-cohesive granular flow of different flow regime and the particle segregation pattern in the resultant deposit through laboratory simulation. The experimental observations revealed that no sustained granular flow sets in on a slope deviating much from the limiting value of the angle of repose of the granular material. A persistent simple shear flow develops on slopes of this critical value. Each of the grains rolls in response to simple shearing. If the shear stress attains a critical value, theoretically the larger grains can even climb up the adjacent smaller ones towards the down-slope direction. In reality, however, high angle climb is not very common. The larger grains preferably roll over the smaller grains when the common tangent becomes almost horizontal or makes a very low angle with the direction of flow, and by this process gradually reaches the upper surface of the flow causing the development of inverse grading. The upper surface of the resultant deposit remains parallel to the sloping substratum. These properties readily distinguish this variety of granular flow from the other natural flows, and the flow may thus be assigned the distinct status of grain-flow.     

Seismic Passive Earth Pressure on Walls with Bilinear Backface Using Pseudo-Dynamic Approach

By using pseudo-dynamic approach, a method has been proposed in this paper to compute the seismic passive earth pressure behind a rigid cantilever retaining wall with bilinear backface. The wall has sudden change in inclination along its depth and a planar failure surface has been considered behind the retaining wall. The effects of a wide range of parameters like soil friction angle, wall inclination, wall friction angle, amplification of vibration, variation of shear modulus and horizontal and vertical seismic accelerations on the passive earth pressure have been explored in the present study. For the sake of illustration, the computations have been exclusively carried out for constant wall friction through out the depth. Unlike the Mononobe-Okabe method, which incorporates pseudo-static analysis, the present analysis predicts a nonlinear variation of passive earth pressure along the wall.     

Biofilm Formation by Microorganisms Isolated from Paper Mill Effluent and its Public Health Implications

The microbiological assessment of biofilm formation from paper mill effluent discharged through a pipeline revealed a maximum microbial count for Pseudomonas (5·10⁶ cfu/mL) followed by Staphylococcus (4·10⁶ cfu/mL), Bacillus (8.2·10⁵ cfu/mL), Burkholderia (7.2·10⁵ cfu/mL), Enterobacter (5.3·10⁴ cfu/mL), Acinetobacter (4.1·10³ cfu/mL), Alcaligenes (1.2·10² cfu/mL) and Klebsiella (0.8·10² cfu/mL) species. Among these species, the maximum biofilm formation was observed after 24 h of incubation by Pseudomonas sp. using a crystal violet (CV) assay. This isolate was later identified by 16S rRNA amplification to be Pseudomonas aeruginosa PME1. Extracellular polymeric substances (EPS) of P. aeruginosa PME1 in the biofilm showed a reduction in total carbohydrate content (42%) with increased protein (9.0%), hexosamine (3.0%) and uronic acid (1.7%) content as compared to its planktonic form. Antimicrobial susceptibility testing revealed that P. aeruginosa PME1 biofilms were 17, 24, 27, 30, and 32 times more resistant to cefotaxime, imipenem, ceftazidime, tazobactam and piperacillin, respectively, than their free flowing counterparts.     

Modeling fractionally integrated maximum temperature series in India in presence of structural break

In this study, the long memory behaviour of monthly maximum temperature of India for the period 1901 to 2007 is investigated. The correlogram of the series reveals a slow hyperbolic decay, a typical shape for time series having the long memory property. Wavelet transformation is applied to decompose the temperature series into time–frequency domain in order to study the local as well as global variation over different scale and time epochs. Significant increasing trend is found in the maximum temperature series in India. The rate of increase in maximum temperature accelerated after 1960s as compared to the earlier period. Here, an attempt is also made to detect the structural break for seasonally adjusted monthly maximum temperature series. It is found that there is a significant break in maximum temperature during July, 1963. Two-stage forecasting (TSF) approach to deal with the coexistence of long memory and structural change in temperature pattern is discussed thoroughly. The forecast performance of the fitted model is assessed on the basis of relative mean absolute prediction error (RMAPE), sum of squared errors (SSE) and mean squared errors (MSE) for different forecast horizons.     

Satellite detection of earthquake thermal infrared precursors in Iran

Stress accumulated in rocks in tectonically active areas may manifest itself as electromagnetic radiation emission and temperature variation through a process of energy transformation. Land surface temperature (LST) changes before an impending earthquake can be detected with thermal infrared (TIR) sensors such as NOAA-AVHRR, Terra/Aqua-MODIS, etc. TIR anomalies produced by 10 recent earthquakes in Iran during the period of Jun 2002–Jun 2006 in the tectonically active belt have been studied using pre- and post-earthquake NOAA-AVHRR datasets. Data analysis revealed a transient TIR rise in LST ranging 2–13°C in and around epicentral areas. The thermal anomalies started developing about 1–10 days prior to the main event depending upon the magnitude and focal depth, and disappeared after the main shock. In the case of moderate earthquakes (<6 magnitude) a dual thermal peak instead of the single rise has been observed. This may lead us to understand that perhaps pre-event sporadic release of energy from stressed rocks leads to a reduction in magnitude of the main shock. This TIR temperature increment prior to an impending earthquake can be attributed to degassing from rocks under stress or to p-hole activation in the stressed rock volume and their further recombination at the rock–air interface. A precise correlation of LST maps of Bam and Zarand with InSAR-generated deformation maps also provides evidence that the thermal anomaly is a ground-related phenomenon, not an atmospheric one.     

Significance of molluscan shell beds in sequence stratigraphy: an example from the Lower Cretaceous Mannville Group of Canada1

Detailed study of marine shales (the Ostracod zone) within a Cretaceous, third-order transgressive-regressive sequence in the Alberta Foreland Basin reveals a systematic association between shell beds and parasequence-scale flooding surfaces, including surfaces of maximum flooding. The Ostracod zone (a subsurface lithostratigraphic unit known as the Calcareous Member in outcrop) consists of 10-20 m of black shale and bioturbated sandstones with many thin, fossiliferous limestones. Parasequences (shallowing-up cycles 2–3 m thick) were delineated within this transgressive unit based on lithology, sedimentary structures, degree of bioturbation, dinoflagellate diversity, total organic carbon and carbon/sulphur ratios; many flooding surfaces are firmgrounds or hardgrounds. Shell-rich limestones occur in three different positions relative to these flooding surfaces, and each has a distinctive bioclastic fabric and origin. (i) Base-of-parasequence shell beds (BOPs) lie on or just above flooding surfaces in the deepest water part of a parasequence; they are thin (up to a few centimetres), graded or amalgamated skeletal packstones/wackestones composed of well-sorted granular shell, and are interpreted as hydraulic event concentrations of exotic shell debris. (ii) Top-of-parasequence shell beds (TOPs) are capped by flooding surfaces at the top, shallowest water part of a parasequence; they typically are several decimetres thick, are physically amalgamated packstones/grainstones or bioturbated wackestones, and contain abundant whole as well as comminuted shells; these are composite, multiple-event concentrations of local shells. (iii) Mid-sequence shell beds rest on as well as are capped by firmgrounds or hardgrounds, and are intercalated between parasequences in the deepest water part of the larger sequence; they are laterally extensive lime mudstones a few decimetres thick, with sparse shells in various states of dissolution, recrystallization and replacement; these beds are terrigenous-starved hiatal concentrations and record maximum flooding within the Ostracod zone. Offshore sections of the Ostracod zone typically contain several starved mid-sequence shell beds, underscoring the difficulty of identifying a single‘maximum flooding surface’ within a third-order sequence.     

Analysis of eve-teasing potential zones using geospatial technologies and AHP: a study in Midnapore town,West Bengal,India

GeoJournal - Application of geospatial technologies in criminological study is most relevant in present day context. Crime mapping with the help of Geographical Information System is being a very...     

Constraints on Titan’s topography through fractal analysis of shorelines

Titan’s north polar hydrocarbon lakes offer a unique opportunity to indirectly characterize the statistical properties of Titan’s landscape. The complexity of a shoreline can be related to the complexity of the landscape it is embedded in through fractal theory. We mapped the shorelines of 290 of the north polar titanian lakes in the Cassini synthetic aperture radar dataset. Out of these, we used a subset of 190 lake shorelines for our analysis. The fractal dimensions of the shorelines were calculated via two methods: the divider/ruler method and the box-counting method, at length scales of (1-10) km and found to average 1.27 and 1.32, respectively. The inferred power-spectral exponent of Titan’s topography (β) from theoretical and empirical relations is found to be ?2, which is lower than the values obtained from the global topography of the Earth or Venus. Some of the shorelines exhibit multi-fractal behavior (different fractal dimensions at different scales), which we interpret to signify a transition from one set of dominant surface processes to another. We did not observe any spatial variation in the fractal dimension with latitude; however we do report significant spatial variation of the fractal dimension with longitude. A systematic difference between the dimensions of orthogonal sections of lake shorelines is also noted, which signifies possible anisotropy in Titan’s topography. The topographic information thus gleaned can be used to constrain landscape evolution modeling to infer the dominant surface processes that sculpt the landscape of Titan.