scholarly journals Soil moisture migration model based on Flux-concentration relation under steady rainfall

2021 ◽  
Author(s):  
Lei Zhang ◽  
Gang Liu ◽  
Ming-zhi Zhao
Keyword(s):  
Moisture Content ◽  
Arbitrary Point ◽  
Constant Concentration ◽  
Moisture Migration ◽  
Migration Model ◽  
Whole Process ◽  
Volumetric Moisture Content ◽  
Long Duration ◽  
Wide Range ◽  
Flux Concentration

Abstract Moisture content distribution in soil is of great importance for understanding rainfall-induced slope failure and roadbed settlement. This study aims to develop a moisture migration model that improves the quantification of moisture content at an arbitrary point of the soil at any time for the whole process of infiltration under steady rainfall. The model was derived from the Richards' equation using the Flux-concentration relation, which was validated by numerical solutions calculated by Hydrus-1D software to evaluate the performance of the model. Results showed good accuracy and high adaptability for the moisture migration simulation of a wide range of soil types, and is applicable for short-duration and long-duration steady rainfall. Moreover, it can also reflect the stratification phenomenon for soil profile wetting by infiltration. Our analysis indicates that the flux and surface volumetric moisture content together can bound the boundary conditions of rainfall infiltration, which presents a shift from constant-flux to constant-concentration during a long-duration steady rainfall. The migration rate of the wetting front in the later stage of infiltration positively correlates with rainfall intensity under the constant-flux condition, while it finally stabilizes at Ks/(θs − θi) under the constant-concentration condition (i.e., Ks-saturated hydraulic conductivity, θs-saturated volumetric moisture content, θi-initial volumetric moisture content). HIGHLIGHT Moisture migration model was derived to improve the quantification of moisture content at an arbitrary point of the soil at any time for the whole process of infiltration under steady rainfall, which shows good accuracy and high adaptability for the moisture migration simulation of a wide range of soil types, and is applicable for short-duration and long-duration steady rainfall.

scholarly journals Moisture Migration and Control of New Embankment for Reconstruction and Expansion Project in Southern China

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Junhui Zhang ◽  
Feng Li ◽  
Ling Zeng ◽  
Junhui Peng ◽  
Le Ding ◽  
...  
Keyword(s):  
Moisture Content ◽  
Southern China ◽  
Stable State ◽  
Element Model ◽  
Capillary Barrier ◽  
Moisture Migration ◽  
Volumetric Moisture Content ◽  
The Difference ◽  
Transient Seepage ◽  
And Control

In hot and humid regions of southern China, the volumetric moisture content of the embankment after opening to traffic for a period of time reaches a stable state, and it is higher than the design value. When it was widened, the humidity gradient and exchange were formed due to the difference in moisture content between the existing and new embankment. To reveal the moisture migration of the existing and new embankment and control the rise of volumetric moisture content in new embankment, six frequency domain reflectometry sensors were installed in existing and new embankment to monitor the volumetric moisture content. A finite element model for the embankment was established and verified with the measured data. And seven numerical analyses of transient seepage in the new embankment of the cushion, cover, and partition using capillary barrier by sand were simulated. The results show that the volumetric moisture contents of the new embankment in southern China gradually increase and eventually reach an equilibrium state. The increase in water comes from the slope, the foundation, and the existing embankment. Early in the first 1∼2 years, the water mainly comes from the foundation and the existing embankment. After that, as time goes by, the water comes mostly from the slope infiltration and gradually migrates to the foundation and the existing embankment. Finally, the volumetric moisture content and the water storage gradually reach equilibrium. The volumetric moisture content of the new embankment using capillary barrier by sand at the cushion, the cover, and the partition is maintained as the construction volumetric moisture content. This combination is a very effective method to control the humidity stability of the new embankment in southern China.

Reduced heart rate variability during sleep in long-duration spaceflight

2013 ◽  
Vol 305 (2) ◽  
pp. R164-R170 ◽  
Author(s):  
D. Xu ◽  
J. K. Shoemaker ◽  
A. P. Blaber ◽  
P. Arbeille ◽  
K. Fraser ◽  
...  
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Substantial Reduction ◽  
Space Station ◽  
Power Spectral Analysis ◽  
Power Spectral ◽  
Long Duration ◽  
Fractal Properties ◽  
Wide Range ◽  
Simultaneous Movement

Limited data are available to describe the regulation of heart rate (HR) during sleep in spaceflight. Sleep provides a stable supine baseline during preflight Earth recordings for comparison of heart rate variability (HRV) over a wide range of frequencies using both linear, complexity, and fractal indicators. The current study investigated the effect of long-duration spaceflight on HR and HRV during sleep in seven astronauts aboard the International Space Station up to 6 mo. Measurements included electrocardiographic waveforms from Holter monitors and simultaneous movement records from accelerometers before, during, and after the flights. HR was unchanged inflight and elevated postflight [59.6 ± 8.9 beats per minute (bpm) compared with preflight 53.3 ± 7.3 bpm; P < 0.01]. Compared with preflight data, HRV indicators from both time domain and power spectral analysis methods were diminished inflight from ultralow to high frequencies and partially recovered to preflight levels after landing. During inflight and at postflight, complexity and fractal properties of HR were not different from preflight properties. Slow fluctuations (<0.04 Hz) in HR presented moderate correlations with movements during sleep, partially accounting for the reduction in HRV. In summary, substantial reduction in HRV was observed with linear, but not with complexity and fractal, methods of analysis. These results suggest that periodic elements that influence regulation of HR through reflex mechanisms are altered during sleep in spaceflight but that underlying system complexity and fractal dynamics were not altered.

scholarly journals Prediction Models for the Estimation of Soil Moisture Content

2011 ◽  
Author(s):  
Swathi Gorthi ◽  
Huifang Dou
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Soil Moisture Content ◽  
Prediction Models ◽  
Recursive Partitioning ◽  
Machine Learning Techniques ◽  
Linear Regression Models ◽  
Remotely Sensed Data ◽  
Modeling Tools ◽  
Wide Range

This paper provides a survey on different kinds of prediction models developed for the estimation of soil moisture content of an area, using empirical information including meteorological and remotely sensed data. The different models employed extend over a wide range of machine learning techniques starting from Basic Linear Regression models through models based on Bayesian framework, Decision tree learning and Recursive partitioning, to the modern non-linear statistical data modeling tools like Artificial Neural Networks. The fundamental mathematical backgrounds, pros and cons, prediction results and efficiencies of all the models are discussed.

The contrast variation of polychromatic speckle patterns at the far-field diffraction plane

1980 ◽  
Vol 58 (10) ◽  
pp. 1439-1445 ◽  
Author(s):  
Y. Tomita ◽  
K. Nakagawa ◽  
T. Asakura
Keyword(s):  
Radial Distance ◽  
Arbitrary Point ◽  
Far Field ◽  
Gaussian Laser Beam ◽  
Contrast Variation ◽  
Diffraction Plane ◽  
Wide Range ◽  
Speckle Patterns ◽  
Average Contrast ◽  
Good Agreement

The contrast variation of polychromatic speckle patterns at an arbitrary point of the far-field diffraction plane is studied theoretically and experimentally. Gaussian statistics are assumed for the formation of speckles. The average contrast of speckle patterns at the far-field diffraction plane is actually theoretically evaluated and experimentally measured for diffuse objects having a wide range of surface roughnesses under illumination of the polychromatic Gaussian laser beam. This contrast is found to depend strongly on the surface roughness of objects, the number of scattering cells within an illuminated area over the object, and a radial distance from the center of the far-field diffraction plane. Good agreement between the theoretical and experimental results is confirmed.

scholarly journals Development of a New Stoichiometric Equilibrium-Based Model for Wood Chips and Mixed Paper Wastes Gasification by ASPEN Plus

2019 ◽  
Author(s):  
Sahar Safarianbana ◽  
Runar Unnthorsson ◽  
Christiaan Richter
Keyword(s):  
Moisture Content ◽  
Aspen Plus ◽  
Wood Chips ◽  
Thermochemical Conversion ◽  
Waste Biomass ◽  
Operation Conditions ◽  
High Heating Value ◽  
Cold Gas Efficiency ◽  
Wide Range ◽  
Steady State Simulation

Abstract Wood and paper residues are usually processed as wastes, but they can also be used to produce electrical and thermal energy through processes of thermochemical conversion of gasification. This study proposes a new steady state simulation model for down draft waste biomass gasification developed using the commercial software Aspen Plus for optimization of the gasifier performance. The model was validated by comparison with experimental data obtained from six different operation conditions. This model is used for analysis of gasification performance of wood chips and mixed paper wastes. The operating parameters of temperature and moisture content (MC) have been varied over wide range and their effect on the high heating value (HHV) of syngas and cold gas efficiency (CGE) were investigated. The results show that increasing the temperature improves the gasifier performance and it increases the production of CO and H2 which leads to higher LHV and CGE. However, an increase in moisture content reduces gasifier performance and results in low CGE.

scholarly journals ODREĐIVANJE HEMIJSKOG SASTAVA RAZLIČITIH EKSTRAKATA ČUVARKUĆE

2021 ◽  
Author(s):  
Jelena Mladenovic ◽  
◽  
Nebojsa Markovic ◽  
Ljiljana Boskovic-Rakocevic ◽  
Milena Đuric ◽  
...  
Keyword(s):  
Herbal Medicine ◽  
Vitamin C ◽  
Moisture Content ◽  
Organic Acids ◽  
Skin Diseases ◽  
Aloe Vera ◽  
First Aid ◽  
Wide Range ◽  
Anti Inflammatory

Sempervivum tectorum has a similar effect as aloe vera, which is known in the treatment of various skin diseases. This herb is considered one of the safest remedies for a wide range of skin diseases. Due to its anti-inflammatory and antiseptic properties, it also serves as an excellent first aid for burns, stings and bites, because it provides quick relief and calming. Freshly squeezed juice from the leaves of the houseplant is used in the treatment of nervous disorders, epilepsy and restless dreams. The leaves are edible and can be used as an addition to salads or stews. They are not particularly tasty, but as they are rich in water, they can be put in a juicer together with other fruits or vegetables and become a refreshing drink. It is used in folk herbal medicine and as a medicine. The aim of this study was to determine the moisture content, total extracted substances, extract density, vitamin C, organic acids and proteins in house extracts.

Soil Resistivity Measurements to Predict Moisture Content and Density in Loose and Dense Soil

2013 ◽  
Vol 353-356 ◽  
pp. 911-917 ◽  
Author(s):  
Mohd Hazreek Zainal Abidin ◽  
Fauziah Ahmad ◽  
Devapriya Chitral Wijeyesekera ◽  
Rosli Saad ◽  
Mohamad Faizal Tajul Baharuddin
Keyword(s):  
Moisture Content ◽  
Soil Condition ◽  
Water Usage ◽  
Soil Resistivity ◽  
Geotechnical Parameters ◽  
Clayey Silt ◽  
Wide Range ◽  
Dry Soil ◽  
Resistivity Meter ◽  
Soil Electrical Resistivity

In the past, most of the soil electrical resistivity charts were developed based on stand-alone geomaterial classification with minimal contribution to its relationship to some of geotechnical parameters. Furthermore, the values cited a very wide range of resistivity with sometimes overlapping values and having little significance to specific soil condition. As a result, it created some ambiguities during the interpretation of observations which were traditionally based on qualitative anomaly judgments of experts and experienced people. Hence, this study presents soil resistivity values based on laboratory experiment with a view to predict the soil moisture content and density in loose and dense soils. This study used a soil box and a resistivity meter to test a clayey silt soil, increasing its water usage from 1-3% based on 1500 gram of dry soil. All the moisture contents and density data were observed concurrently with 25 electrical soil resistance observations being made on the soil. All testing and formula used were in accordance with that specified in BS1377 (1990). It was apparent that the soil resistivity value was different under loose (L) and compact (C) condition with moisture content (w) and density (ρbulk) correlations being established as follows; ρbulk(C) = 2.5991ρ-0.037, ρbulk (L) = -0.111 ln (ρ) + 1.7605, w(L) = 109.98ρ-0.268, and w(C) = 121.88ρ-0.363 with determination coefficients, R2 that ranged between 0.69 0.89. This research therefore contributes a means of predicting these geotechnical parameters by related persons such as geophysicist, engineers and geologist who use these resistivity techniques in ground exploration.

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