577 research outputs found
Modeling Earthen Dike Stability: Sensitivity Analysis and Automatic Calibration of Diffusivities Based on Live Sensor Data
The paper describes concept and implementation details of integrating a
finite element module for dike stability analysis Virtual Dike into an early
warning system for flood protection. The module operates in real-time mode and
includes fluid and structural sub-models for simulation of porous flow through
the dike and for dike stability analysis. Real-time measurements obtained from
pore pressure sensors are fed into the simulation module, to be compared with
simulated pore pressure dynamics. Implementation of the module has been
performed for a real-world test case - an earthen levee protecting a sea-port
in Groningen, the Netherlands. Sensitivity analysis and calibration of
diffusivities have been performed for tidal fluctuations. An algorithm for
automatic diffusivities calibration for a heterogeneous dike is proposed and
studied. Analytical solutions describing tidal propagation in one-dimensional
saturated aquifer are employed in the algorithm to generate initial estimates
of diffusivities
New spectral functions of the near-ground albedo derived from aircraft diffraction spectrometer observations
The airborne spectral observations of the upward and downward irradiances are
revisited to investigate the dependence of the near-ground albedo as a
function of wavelength in the entire solar spectrum for different surfaces
(sand, water, snow) and under different conditions (clear or cloudy sky). The
radiative upward and downward fluxes were determined by a diffraction
spectrometer flown on a research aircraft that was performing multiple flight
paths near the ground. The results obtained show that the near-ground albedo
does not generally increase with increasing wavelengths for all kinds of
surfaces as is widely believed today. Particularly, in the case of water
surfaces it was found that the albedo in the ultraviolet region is more or
less independent of the wavelength on a long-term basis. Interestingly, in
the visible and near-infrared spectra the water albedo obeys an almost
constant power-law relationship with wavelength. In the case of sand surfaces
it was found that the sand albedo is a quadratic function of wavelength,
which becomes more accurate if the ultraviolet wavelengths are neglected.
Finally, it was found that the spectral dependence of snow albedo behaves
similarly to that of water, i.e. both decrease from the ultraviolet to the
near-infrared wavelengths by 20–50%, despite the fact that their values
differ by one order of magnitude (water albedo being lower). In addition, the
snow albedo vs. ultraviolet wavelength is almost constant, while in the
visible near-infrared spectrum the best simulation is achieved by a
second-order polynomial, as in the case of sand, but with opposite slopes
Slope Instability of the Earthen Levee in Boston, UK: Numerical Simulation and Sensor Data Analysis
The paper presents a slope stability analysis for a heterogeneous earthen
levee in Boston, UK, which is prone to occasional slope failures under tidal
loads. Dynamic behavior of the levee under tidal fluctuations was simulated
using a finite element model of variably saturated linear elastic perfectly
plastic soil. Hydraulic conductivities of the soil strata have been calibrated
according to piezometers readings, in order to obtain correct range of
hydraulic loads in tidal mode. Finite element simulation was complemented with
series of limit equilibrium analyses. Stability analyses have shown that slope
failure occurs with the development of a circular slip surface located in the
soft clay layer. Both models (FEM and LEM) confirm that the least stable
hydraulic condition is the combination of the minimum river levels at low tide
with the maximal saturation of soil layers. FEM results indicate that in winter
time the levee is almost at its limit state, at the margin of safety (strength
reduction factor values are 1.03 and 1.04 for the low-tide and high-tide
phases, respectively); these results agree with real-life observations. The
stability analyses have been implemented as real-time components integrated
into the UrbanFlood early warning system for flood protection
Distributed simulation of city inundation by coupled surface and subsurface porous flow for urban flood decision support system
We present a decision support system for flood early warning and disaster
management. It includes the models for data-driven meteorological predictions,
for simulation of atmospheric pressure, wind, long sea waves and seiches; a
module for optimization of flood barrier gates operation; models for stability
assessment of levees and embankments, for simulation of city inundation
dynamics and citizens evacuation scenarios. The novelty of this paper is a
coupled distributed simulation of surface and subsurface flows that can predict
inundation of low-lying inland zones far from the submerged waterfront areas,
as observed in St. Petersburg city during the floods. All the models are
wrapped as software services in the CLAVIRE platform for urgent computing,
which provides workflow management and resource orchestration.Comment: Pre-print submitted to the 2013 International Conference on
Computational Scienc
Impedance spectroscopy of synthetic proustite at high pressures
The effect of high pressure (up to 40 GPa) and alternating electric field frequency (100 Hz-500 kHz) on the electrical properties of synthesized single-crystal proustite Ag3AsS3 is studied. The behavior of real and imaginary parts of impedance upon an increase in pressure confirms earlier data on the closing of valence and conduction zones, and on the material's transition to the metal state at ∼30 GPa. © 2013 Allerton Press, Inc
The Rehydration Ability of Whey Ingredients
The purpose of this research was to studythe ability of whey protein concentrates (WPC) and whey permeate produced with ultrafiltration of cheese whey to rehydrate. The products studied were cheese whey concentrate witha PDM percentage of 80% (WPC-80), and cheese whey permeate, both produced under the conditions of the PJSC Dairy “Voronezhsky”.WPC-80 and the whey permeate dissolution processes were studied using microscopy. Water-impermeable hydrophobic layers were formed at the boundary, preventing water penetration into dry particles. The result was a higher dissolution timeforWPC-80 compared with whey permeate. When WPC-80 came into contact with water,it initially formed an obtuse wetting angle with a slow change over time. Whey permeate reached the equilibrium wetting angle more quickly. Quickreconditioning of WPC moisture content required avoiding capillary penetration of water, which created a turbulent liquid flow. The application of these ingredients in different food industry areas can reduce the costs for finished products, contribute to cost-effectiveness, increase the total production, and reduce environmental risks.
Keywords: whey protein concentrate, whey permeate powder, water-wetting, dissolutio
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