The stability of internal gravity waves in a bounded atmospheric shear layer in the presence of moisture

The stability characteristics of internal gravity waves, generated by an isothermal bounded tangent velocity profile in the presence of a saturated finite layer, are studied. The moist layer with constant thickness the structure of the ness is introduced at different levels in respect to the point of inflection and the variations of moisture content and distance from the origin are examined. The characteristics of the unstable waves are obtained by solving numerically the linearized versions or the full equations of motion, in the inviscid and Boussinesq limit, through the technique of Lalas and Elnaudi (1976). It is shown that the presence of the moist layer can significantly affect the stability characteristics of the waves. Increases in the moisture and distance of the layer from the Inflection point are found to amplify or decay the wave response, because the saturated layer behaves as a solid boundary to the flow. The presence of such effective layer is shown to stabilize short wavelengths and destabilize. Finally, an application of the model's results to the real atmosphere is discussed.

A linear stability analysis of two-layer moist convection with a saturation interface

The linear convective instability of a mixture of dry air, water vapour and liquid water, with a stable unsaturated layer residing on an unstable saturated layer, is studied. It may serve as a prototype model for understanding the instability that causes mixing at the top of stratocumulus cloud or fog. Such a cloud-clear air interface is modelled as an infinitely thin saturation interface where radiative and evaporative cooling take place. The interface position is determined by the Clausius–Clapeyron equation, and can undulate with the evolution of moisture and temperature. In the small-amplitude regime two physical mechanisms are revealed. First, the interface undulation leads to the undulation of the cooling source, which destabilizes the system by superposing a vertical dipole heating anomaly on the convective cell. Second, the evolution of the moisture field induces non-uniform evaporation at the interface, which stabilizes the system by introducing a stronger evaporative cooling in the ascending region and vice versa in the descending region. These two mechanisms are competing, and their relative contribution to the instability is quantified by theoretically estimating their relative contribution to buoyancy flux tendency. When there is only evaporative cooling, the two mechanisms break even, and the marginal stability curve remains the same as the classic two-layer Rayleigh–Bénard convection with a fixed cooling source.

Study of mining tailings geotechnical parameters obtained from SCPTu tests carried on dry and saturated layers

The correct interpretation of in situ and laboratory test results is an important step in the design of mining tailing containment structures. This study aims to analyze the Seismic Cone Penetration Test (SCPTu) results obtained into a mining tailing reservoir composed of two material layers: a thick-dry and a tick-saturated. It is possible to observe that in a same tailing reservoir, the CPTu test interpretation can lead to a classification of each layer as a different soil with specific behavior and properties. This condition demonstrates that tailings with intermediate permeability (10-5 m/s < k < 10-8 m/s) may present partial drainage conditions during a standard cone penetration test (CPTu) (v=20 mm/s), if saturated conditions are verified. The effects of partial drainage can affect test results, and can induce to errors in the prediction of soil behavior and geotechnical parameters. To evaluate the possible effects of partial drainage, in situ test results were compared to laboratory tests results. It was possible to verify that estimated behavior of dry layers, obtained from in situ tests results, present more similarity to the results from laboratory tests. Probably, the partial drainage effects verified through the interpretation of dissipation tests, distorted the estimated behavior of the saturated layer material.

Investigasi Pendugaan Gerakan Tanah Menggunakan Metode Electrical Resistivity Tomography dan Self Potential di Daerah Pasanggrahan Baru, Sumedang Selatan

Land movement occur because of the movement of slope-forming material such as of soil, rock or a combination of material types to a place that is lower due to the influence of gravity. The movement of slope material can be identified by the Electrical Resistivity Tomography (ERT) Method, because this method has good lateral and vertical resolution based on rock resistivity data. The trigger factors for land movement in Anjung Village, Pasanggrahan Baru, South Sumedang, among others: an increase in water content on the slopes and the slip plane. Increased water content is influenced by infiltration of rainwater as one of the triggers of land movement, can be detected by the Self Potential method (SP), while the slip plane can be detected by the method of Electrical Resistivity Tomography (ERT). Based on the results of the ERT and SP measurements, the results are: debris flow as a landslide plane (resistivity values: 31 – 170 Ohm.m and SP values: 5 – 13 mV), water table/water saturated layer (resistivity values: 1 – 13 Ohm.m and SP values: 14 – 34 mV), and breccias (resistivity values: 400 - 900 Ohm.m and SP values: 1-3 mV).Slip plane are estimated to be at boundary between the breccia and the material on it.Keywords: Land movement, resistivity, self potential, South Sumedang

Behavioral Analysis of Hydrogen in Metals under the Effect of H2S Corrosion Using a Layer-stripping Micro-hardness Technique

In order to study the distribution behavior of hydrogen in metals under the condition of H2S corrosion, a layer-stripping micro-hardness test was designed to analyze the hydrogen distribution along the depth of hydrogen-charged 45 high-quality structural carbon steel at three different hydrogen sulfide concentrations and four corrosion periods in this study. The results show that there is a terminal solid solubility of hydrogen in the metal for hydrogen sulfide solutions over various concentrations and corrosion periods. A hydrogen-saturated layer is produced by hydrogen diffusing through the metal from an unsaturated state to a fully saturated state. The hydrogen-saturated layer is not affected by the concentration of the corrosion, but its thickness increases as the corrosion period increases. In this way, we established a new hydrogen diffusion model in metals.

Quick analysis of the characteristic hydrogeological parameters of an aquifer, using empirical formulas and the implementation of the clay substrate map: the case study of the shallow aquifer of the S. Eufemia Lamezia plain (Central Calabria - Italy).

In Calabria, there are few works of quantitative hydrogeology. Therefore, the present study aims to provide a contribution to the hydrogeological knowledge of the region and, in particular, of the shallow aquifer of the S. E. Lamezia plain, characterized by a multi-layer aquifer. The study area is located in the Tyrrhenian sector of the “Graben of Catanzaro, an important tectonic structure in the wider context of the Calabrian Peloritano Arc. The acquisition of new lithostratigraphic and hydrogeological data, related to drillings for water research, has allowed expanding the knowledge of the phreatic aquifer of S. E. Lamezia plain. In the study area, there is a high number of abusive wells without data, not declared and are made without a basic hydrogeological study. Therefore, they are free of flow rate tests and information about the drilling depth, stratigraphy and construction methods. However, a certain numbers of wells is authorized and the available data are: Stratigraphy, static and dynamic level, critical flow rare (Qc) and, in some cases, also the specific lowering (Δs). Therefore with these data, using empirical formulas, a quick analysis of the hydrogeological parameters characteristic of the aquifer it was done. Moreover, interpolating the stratigraphic data with a geostatistic method the map of the clay substrate was returned. In particular, the Transmissivity [T] and the Storage coefficient [S] were calculate with empirical formulas using well data. From the Transmissivity. the Hydraulic conductivity [K] is derived. The hydraulic gradient from the piezometric map graphically is calculated. The thickness of the saturated layer (b) of the aquifer was obtained directly from the stratigraphy of the wells surveyed or, in those cases in which stratigraphy was not known, from the differences between the values obtained from the isopiezometric map and the map of the clay substrate. In conclusion, this study, with the implementation of the clay substrate map and a quick analysis of the main hydrodynamic parameters, aims to provide a contribution to the definition of the hydrogeological model of the shallow aquifer of the Plain that represents a fundamental tool for the protection and the correct management of the water resource.