Fig 5 - uploaded by Jose Antonio Gutierrez Gnecchi
Content may be subject to copyright.
Block diagram of the power supply. A) The battery feeds a linear voltage regulator. B) the output from the regulator is increased to (over) +30 V to power up the instrumentation amplifier. The battery feeds a low dropout, adjustable linear regulator (TPS7101 from Texas Instruments©) which provides the regulated supply voltage to the DC/DC converter (Fig. 6).
Context in source publication
Context 1
... first step in developing the instrumentation circuitry consists of obtaining a little over +30V from a +9V battery, because interfacing with the data logger requires that the analogue instrumentation operate with a voltage slightly over 30V. The circuit must be small and must consume very little current from the battery. Fig. 5 shows the block diagram of the power supply. The battery feeds a low dropout, adjustable linear regulator (TPS7101 from Texas Instruments©) which provides the regulated supply voltage to the DC/DC converter (Fig. 6). The TPS7101 output voltage is adjusted to +8.3V by trimming R1 which is a 1 MegaOhm, 20 turns, trimming potentiometer. ...
Citations
... van Genuchten (1980); Durner (1994); Durner and Flühler (2006)). Hydraulic conductivity can be considered as an indispensable parameter for soil characterization, simulation of water and mass transport in vadose and saturated zone, management of soil organic matter and sustainable development of regional water resources (Gutierrez Gnecchi et al., 2011). ...
... Empirical methods based on systematic data collection are used as to correlate K s with soil properties like particle size, soil texture, pore size and relative effective porosity (Gootman et al., 2020;Gupta et al., 2020;Huang et al., 2019;Hwang et al., 2017;Picciafuoco et al., 2019;Vereecken et al., 2010Vereecken et al., , 1992Wösten et al., 1999). Experimental methods are distinguished in laboratory and field methods (Durner and Flühler, 2006;Gutierrez Gnecchi et al., 2011;Morbidelli et al., 2017). However, the adequacy and cost-effectiveness of these methods can often be a limiting factor in soil-water modeling applications. ...
... However, the adequacy and cost-effectiveness of these methods can often be a limiting factor in soil-water modeling applications. In this concept, although the number of methods and apparatuses used is quite large, it is still a need to elaborate new methodological approaches and instrumentation technologies to enhance the quality and quantity of reliable information and to provide alternative options to address the uncertainty of hydraulic parameters estimations (Gamie and De Smedt, 2018;Gutierrez Gnecchi et al., 2011;Zhang et al., 2007). A physical analogue for soil water movement can be modelled with the Hele-Shaw (Hele-Shaw, 1898) apparatus. ...
The estimation of saturated hydraulic conductivity is a key parameter for studying the water flow in the unsaturated zone of the soil. In this work, a combined modelling approach of the waterfront movement is elaborated, integrating a physical analogue type device with image analysis. A customized Hele-Shaw apparatus is designed for the wetting process visual inspection, while an optical flow algorithm is used for the numerical calculation of flow velocity and saturated hydraulic conductivity values at a pixel level of the image processing. Saturated hydraulic conductivity values estimated by the proposed method are in close agreement with values found in the literature under similar soil conditions. Also, the proposed method seems to be a useful tool for a comprehensive analysis of the waterfront movement in the vadose zone.
Permeability is a vital parameter for the design and construction of structures involving ocean engineering. Based on the steady-state heat transfer theory and Darcy's law, a novel in-situ test method for permeability in saturated sandy porous media is introduced in this work. This approach aims to obtain permeability through the inversion of the measured temperatures. Temperatures measuring device with a constant heater was installed in an insulating experimental tank filled with sandy sediments of different permeability. Further, a numerical model based on the Finite Element method was simulated to validate the feasibility of the proposed method and accuracy of the experimental data. Besides, the results obtained by the constant head test were compared with those calculated by the novel in-situ test method, considering different surface temperatures of the heater and different sediments’ permeability. It shows that the permeability obtained by in-situ method are reliable and accurate (the accuracy is within one order of magnitude) in both numerical simulations and experimental tests. The effects of different surface temperatures of the heater and permeability of porous media on permeability calculation results were also discussed. The surface temperature was found that has little influence on permeability. And the proposed method is applicable when the permeability is higher than 10⁻¹² m². The findings can provide some reference to the in-situ measurement of submarine sediments' permeability.
