Laboratory simulation to understand translational soil slides and establish movement criteria using wireless IMU sensors

Landslide monitoring and warning using inertial measurement units (IMUs) has shown the potential for remote and real-time applications. However, the studies conducted using the IMU sensors are limited to rainfall-induced landslide detection using soil moisture sensors and accelerometers for predicting slide and measuring tilt, respectively. The tilting of the slope might not occur during a slow-moving translational slide, and it may not always be possible to accurately record the soil moisture condition. The use of raw acceleration data, which is the combination of linear and gravitational accelerations, for calculating tilt or motion is another drawback of the existing studies. Hence, there is a need for a better approach to monitor slides. This paper presents two methods to define movement thresholds and criteria to identify the translational soil slides based on our understanding of the sensor data recorded during the two laboratory experiments. BNO055 sensor devices (IMU sensors) with 3-axis accelerometers and 3-axis gyroscopes were selected for this study. The linear accelerations, gravitational accelerations, and angular velocities were utilized to understand the translational soil slides by correlating the sensor behavior to that of the slope. The interpretation of the movements during the failure at each sensor location was further verified by referring to the videos recorded by two pi-cameras. The outcomes of this study confirm the applicability of the proposed IMU sensor system and the movement thresholds for effective and reliable monitoring and warning of translational soil slides.     

Design Charts for Selecting Minimum Setback Distance from Side Slope to Horizontal Trench System in Bioreactor Landfills

The primary objective of bioreactor landfill is to achieve adequate and rapid distribution of moisture in landfilled municipal solid waste (MSW) to accelerate the anaerobic biodegradation of the organic fraction within MSW. A horizontal trench system (HT) is commonly adopted for leachate distribution in MSW under pressurized conditions. However, this approach should be implemented carefully due to the potential instability of landfill slopes that comes from the generation and distribution of excessive pore fluid pressures. In this study, HT design charts are presented that determine the optimal location of horizontal trench systems from the side slope (i.e., minimum lateral setback distance) under continuous leachate addition with maximum applied injection pressures, for which the landfill slopes remain stable [factor of safety (FOS) where FOS ≥ 1.5]. Use of any higher injection pressure and/or shorter lateral setback distance of HT than the one presented in the design charts would result in an unacceptable design of the bioreactor side slope (FOS < 1.5). The design chart was developed based on a parametric study that used a numerical two-phase flow model that involved different slope configurations and landfill waste depths. MSW heterogeneity and anisotropy, as well as unsaturated hydraulic properties, were taken into consideration in these simulations. Transient changes in pore water and gas pressures due to leachate recirculation were accounted for dually in the slope stability computations. The importance of these design charts is illustrated using a practical example. Site-specific conditions and the expertise and prior experience of a designer or operator must also be adequately considered and utilized with the design charts presented here for the safe design of a horizontal trench system in a bioreactor landfill.     

Horizontal trench system effects on leachate recirculation in bioreactor landfills

Horizontal trenches (HTs) are constructed during the waste filling for leachate recirculation in bioreactor landfills. Leachate distribution depends on HT configuration (i.e., spacing between successive HTs), leachate injection rate, modes of injection, and hydraulic properties and MSW heterogeneity. Presently, the effects of these variables on the moisture distribution have not been studied systematically. This study provides a systematic evaluation of the effect of the HTs variables on the moisture distribution and pore fluid pressures. A two-phase flow model is used to model a bioreactor landfill having an HT leachate injection system. It quantifies the effects of the unsaturated hydraulic properties and MSW heterogeneity, trench configuration, leachate injection flux, and mode of injection on hydraulic behaviour. The results show that unsaturated hydraulic conductivity and MSW heterogeneity significantly shape the zone of influence and excess pore pressures. Under heterogeneous-anisotropic conditions, the leachate migrates more laterally and the developed pore-pressures are lower than for homogeneous MSW. A closely-spaced, multi-level, staggered HT system is found to provide uniform and adequate moisture distribution in MSW. An intermittent mode of injection that alternates between the shallow and deep trenches with a higher leachate injection flow rate is found to be effective to control the excess pore pressures.     

The Mutual Response of the Tropical Squall Line and the Ocean

—The Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPS) is used to investigate the mutual response of a tropical squall line and the ocean. Simulated squall line compares well with the observations, and consists of counterrotating vortices, and has a bow shape bulge toward the leading edge. In addition to these features, which are also shown in the previous numerical simulations, the unique results from the coupled simulation indicate that the air–sea interaction processes within the squall line are important. They affect both the atmosphere and the ocean locally. Simulated upper ocean displays significant response to the squall line with upwelling and baroclinicity. Depth of the ocean mixed layer in the coupled simulation becomes modified due to feedback processes. Ocean temperature acts as a destabilizing factor, and the salinity as a stabilizing factor. Surface turbulent fluxes from the coupled simulation are about 10% less than that of the uncoupled simulation. The SST in the coupled simulation decreases by about 0.21°C. Predicted squall line in the coupled simulation is weaker as compared to the uncoupled simulation. This is reflected in terms of differences in surface fluxes, cloud water, rain water and vertical velocities between the two simulations.     

Role of the Land Plume in the Transport of Ozone Over the Ocean During Indoex (1999)

Observations from aircraft, an island station, and tworesearch vessels are used to investigate the development of an elevated mixed layeror land plume over the Arabian sea during the Indian Ocean Experiment Intensive FieldPhase 1999 (INDOEX) through air mass modification. Much of the transport of aerosolsand gases occurs in this plume located above a well-mixed convective marine boundary layerwith a depth of 800–1000 m. The depth of the land plume isapproximately 2000 m with the peak ozone concentrations occurring near the centre of this land plume.Significant latitudinal variations in the concentration of ozone occur in the marineboundary layer and in the plume. Mean ozone concentrations in the land plume decreasedwith distance from the Indian coastline.     

A case study of the nocturnal boundary layer over a complex terrain

A case study of the structure of the nocturnal boundary layer (NBL) over complex terrain is presented. Observations were made during the third night of Project STABLE (Weber and Kurzeja, 1991), whose main goal was to study turbulence and diffusion over the complex terrain of the Savannah River Site (SRS) near Augusta, Georgia.The passage of a mesoscale phenomenon, defined as a turbulent meso-flow (TMF) with an explanation of the nomenclature used, and a composite structure of the lowest few hundred meters over complex terrain are presented. The spatial extent of the TMF was at least 30–50 km, but the forcing is not well understood. The TMF occurred without the presence of a synoptic-scale cold front, under clear conditions, and with no discernible discontinuity in a microbarograph pressure trace. The structure of the NBL over the complex terrain at SRS differed from the expected homogeneous terrain NBL. The vertical structure exhibited dual low level wind maxima, dual inversions, and a persistent elevated turbulent layer.The persistent elevated turbulent layer, with a spatial extent of at least 30 km, was observed for the entire night. The persistent adiabatic layer may have resulted from turbulence induced by shear instability.     

The variation of filament direction in a flaring region

We have analyzed the variations in shear angle over a time interval of 30 s during a flare on June 11, 1991, using Kodaikanal Observatory spectroheliogram and photoheliogram data, and assuming H filaments are a proxy for the neutral lines. The changes in shear angles have been analysed at two points of the filament. The orientation of the H filament underwent a considerable change of 55° from June 10, 1991 to prior to the start of the flare on June 11, 1991. The photoheliogram on June 10, 1991 shows considerable twisting of the umbrae (in one common penumbra) and broke into parts before the onset of the flare on June 11, 1991. The twisting of umbrae on June 10, 1991 shows that sunspot proper motion plays an important role in bringing a non-potential character to the field lines. This in turn develops shear and kink and it is argued that changes in filament orientation over a small interval of a half minute triggers the eruption of the flare.     

Effects of magnetic shear,spot, and plage rotation on prominence evolution

We have studied the evolution of two dark H filaments as prominences during their disk passage from 12 to 19 February, 1992 and 6 to 17 March, 1992, using Kodaikanal Observatory H and Caii K spectroheliograms. Both the filaments were well outside the spot regions. However, they were connected to sunspots by small threads. Outside the spot regions, the filaments were also anchored between opposite polarity plage regions. Both the filaments were almost straight in the beginning. However, they acquired a curved shape (inverted U-shape) as the spot and plages underwent rotation. It is shown that rotation of the plage and spot plays an important role in the evolution of prominences, one serving as the anchor and the other imparting necessary shear. Once the shear reaches a critical value it starts unwinding the filaments, resulting in the fine structure of the two prominences studied.     

Sunspot Motions Associated with Flares

The evolution of five bipolar sunspot groups during their disk passage leading to flares are analysed and studied using Kodaikanal Observatory photoheliogram and spectroheliogram data. The changes in the orientation angle observed in the spot groups show that sunspot proper motion plays an important role in introducing non-potential character to the field lines. This in turn develops shear and once the shear reaches a critical value, the flare eruption is triggered. The rotational motions in the sunspots are measured from the change in their orientation angle and are given as a measure of shear. The sunspots considered for analyses in the present study are not associated with any filament activity.