scholarly journals MATHEMATICAL MODEL OF SALINITY INTRUSION IN THE DELTA OF THE PO RIVER

1974 ◽  
Vol 1 (14) ◽  
pp. 134 ◽  
Author(s):  
Renzo Dazzi ◽  
Mario Tomasino
Keyword(s):  
Good Description ◽  
Salt Water ◽  
Water Layer ◽  
Interfacial Stress ◽  
Po River ◽  
Thermo Electric ◽  
Salt Wedge ◽  
Stress Coefficient ◽  
Grid Points ◽  
The One

A general numerical model capable of reproducing long inter_ nal waves in stratified fluids has been constructed with the aim of investigating the salt wedge penetration in the Delta of the Po river, where the installation of a 2640 MW thermo-electric plant is foreseen. The working hypothesis of the model, in accordance with the actual phenomenology of the river, is the one-dimensional homogeneous motion of two fluid layers of different density. The main original aspects of the numerical computation are: 1) - The use of two different space steps (1 km for the fresh water layer; 200 m for salt water) simultaneously allowing a good description of internal waves (the velocity of which is much smaller than that of the external ones) and making it possible to work with economic (100 sec) time steps. 2) - The straightforward description of the wedge head, obtained by making it always freely correspond to one of the grid points. The model, which has been tested on actual events, reproduces reality with a very good approximation; it also gives evidence of the small relevance of the interfacial stress coefficient in unstea dy tidal generated motion of the salt wedge.

scholarly journals ESTUARINE CURRENTS AND TIDAL STREAMS

2011 ◽  
Vol 1 (7) ◽  
pp. 28
Author(s):  
Roderick Agnew
Keyword(s):  
Fresh Water ◽  
River Flow ◽  
Salt Water ◽  
Three Dimensional ◽  
Vertical Plane ◽  
Water Layer ◽  
Wave Theory ◽  
Constant Density ◽  
Salt Wedge ◽  
Tidal Streams

Fresh water spreading out from the mouth of a river as it enters a salt sea may preserve its identity for a considerable distance on the surface if wind-generated waves, longshore currents and tidal streams are capable of producing only weak mixing. Fig. 1 shows the three dimensional shape of a fresh-water tongue overlying more dense salt water, derived by Takano (1954) on the assumption of constant eddy viscosity and constant density in the fresh water layer, below which the density increases according to an assumed law, making an asymptotic approach to the density of salt water. Takano's model is thus a water jet entraining salt from around and below it. Salt or brackish water may penetrate along the deep channels of an estuary in the shape of a wedge complementary to the fresh water tongue, the salt wedge retreating seawards as heavy rainfall increases the river discharge, and advancing in dry weather intervals. Tidal streams cause a regular oscillation of both fresh and braok water in flood and ebb directions but the seasonal movements of the sloping boundary between fresh and salt water may still be important in low-lying delta regions. Strong tidal streams lead to intense mixing, when neither a fresh water tongue nor a salt wedge can be distinguished, but the isohalines (salinity contours) preserve the general wedge pattern - see Figs. 3 to 6. In the upper reaches of an estuary it is possible to study the effect of the tidal motion by treating it as a simple harmonic perturbation of the uni-directional river flow. Even in the middle portion of the estuary where there is reversal of the horizontal motion, one may seek a "quasi steady" solution for the net effect (seaward movement of fresh water) while allowing for the increased turbulence due to the tidal action. At the seaward end of the estuary there is little deviation from the astronomical tidal rhythm, so the problem reduces to simple harmonic oscillations of salt water. Higher harmonics may be introduced as an extension of the simple solution. For a first approximation it is sufficient to consider flow in the longitudinal vertical plane, to assume that the pressure distribution is hydrostatic as in long wave theory, and even to neglect inertia terms when investigating net effects.

On the thermo-electric power of metals

1955 ◽  
Vol 228 (1175) ◽  
pp. 568-574 ◽  
Keyword(s):  
Electric Power ◽  
Alkali Metals ◽  
Phonon Scattering ◽  
Opposite Sign ◽  
Order Effects ◽  
Lattice Distribution ◽  
Thermo Electric ◽  
The One ◽  
Electric Effect ◽  
Electron Phonon Scattering

Makinson’s extension of Wilson’s treatment of the second-order effects in metals is used to derive an expression for the contribution of the lattice current to the thermo-electric power of metals at those temperatures where electron-phonon scattering predominates. It is found that in this temperature region one may expect the thermo-electric effect to show a sign opposite to the one which follows from the simple electron theory of metals. This is because the term due to the departure from equilibrium of the lattice distribution is larger than the usual term and is of opposite sign. If the temperature is greatly decreased or increased, the usual term predominates. The effect discussed may have a bearing on the behaviour of the thermo-electric power of the alkali metals, although it cannot explain this behaviour completely.

Testing of the foreshock hypothesis within an epidemic like description of seismicity

2020 ◽  
Author(s):  
G Petrillo ◽  
E Lippiello
Keyword(s):  
Seismic Activity ◽  
Good Description ◽  
Aftershock Sequence ◽  
Short Term ◽  
Etas Model ◽  
Temporal Clustering ◽  
Epidemic Type Aftershock Sequence ◽  
Preparatory Phase ◽  
Spatio Temporal ◽  
The One

Summary The Epidemic Type Aftershock Sequence (ETAS) model provides a good description of the post-seismic spatio-temporal clustering of seismicity and is also able to capture some features of the increase of seismic activity caused by foreshocks. Recent results, however, have shown that the number of foreshocks observed in instrumental catalogs is significantly much larger than the one predicted by the ETAS model. Here we show that it is possible to keep an epidemic description of post-seismic activity and, at the same time, to incorporate pre-seismic temporal clustering, related to foreshocks. Taking also into-account the short-term incompleteness of instrumental catalogs, we present a model which achieves very good description of the southern California seismicity both on the aftershock and on the foreshock side. Our results indicate that the existence of a preparatory phase anticipating mainshocks represents the most plausible explanation for the occurrence of foreshocks.

scholarly journals Multilayered salt water with high optical transparency for EMI shielding applications

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Duy Tung Phan ◽  
Chang Won Jung
Keyword(s):  
Electromagnetic Interference ◽  
Light Transmission ◽  
Salt Water ◽  
Water Layer ◽  
Visual Observation ◽  
Optical Transparency ◽  
Shielding Effectiveness ◽  
Emi Shielding ◽  
Multilayered Structures ◽  
X Band

AbstractElectromagnetic interference (EMI) shielding for visual observation applications, such as windows utilized in military or aerospace, is important but difficult to realize due to conventional materials having difficulty in achieving sufficient transparency and EMI shielding simultaneously. In this paper, we present multilayered structures based on salt water for simultaneous highly optical transparency (OT) and EM shielding effectiveness (SE) performance. In the proposed structures, planar acrylic and glass were used as two types of clear substrates to hold salt water. The measured OT of both acrylic/salt water/acrylic and glass/salt water/glass structures was higher than 90% with a nearly uniform light transmission, which introduced a negligible impact on optical observation. Furthermore, both simulations and experimental results demonstrated that the SE of the multilayer structure was higher than 20 dB in the X-band from 7.5 to 8.5 GHz. Moreover, the SE was significantly enhanced by increasing the thickness of the salt water layer. Especially, both OT and SE of the multilayered structures were improved simultaneously by increasing the salinity of the salt water. These proposed structures demonstrate great potential in EMI shielding observation applications.

X. A Letter from W. E. Rouse Boughton, Esq. F.R.S. to the Rev. Stephen Weston, B. D. respecting some Egyptian Antiquities

Archaeologia ◽  
1817 ◽  
Vol 18 ◽  
pp. 59-72
Author(s):  
W.E. Rouse Boughton
Keyword(s):  
Great Britain ◽  
Salt Water ◽  
Upper Egypt ◽  
Good Fortune ◽  
Birth Place ◽  
The One ◽  
Sacred History

During my travels in Upper Egypt, in the course of the year 1811, I had the good fortune to meet with a mummy, in a catacomb near Thebes, which appeared never to have been opened before, containing some writing upon papyrus in a state of perfect preservation; and as these writings are but rarely found in mummies, I felt great anxiety to bring the one which fell into my hands safe to Great Britain. For this purpose I had a tin box made for holding it, in order to prevent it from being crushed amongst my packages. I myself proceeded by land to Constantinople; but having sent my baggage by sea, it was unluckily soaked by salt water, and the tin case corroded, so as greatly to injure the manuscript. I have, however, collected some of the fragments, and made accurate copies of them (Pl. I. II.), which I have now the honour of presenting to the Society of Antiquaries; conceiving that they may afford additional specimens of the antient Egyptian character, of which I believe there are not many in Great Britain, and may possibly contribute to the assistance of scientific men, in various parts of Europe, who are giving their attention to that interesting country, established by all profane and sacred history to have been the birth-place of science and wisdom.

The evolution of under-ice melt ponds, or double diffusion at the freezing point

1974 ◽  
Vol 64 (3) ◽  
pp. 507-528 ◽  
Author(s):  
Seelye Martin ◽  
Peter Kauffman
Keyword(s):  
Fresh Water ◽  
Sea Water ◽  
Freezing Point ◽  
Salt Water ◽  
Ice Sheet ◽  
Water Layer ◽  
Double Diffusion ◽  
Theoretical Models ◽  
Interfacial Region ◽  
Ice Melt

In an experimental and theoretical study, we model a phenomenon observed in the summer Arctic, where a fresh-water layer at a temperature of 0°C floats both over a sea-water layer at its freezing point and under an ice layer. Our results show that the ice growth in this system takes place in three phases. First, because the fresh-water density decreases upon supercooling, the rapid diffusion of heat relative to salt from the fresh to the salt water causes a density inversion and thereby generates a high Rayleigh number convection in the fresh water. In this convection, supercooled water rises to the ice layer, where it nucleates into thin vertical interlocking ice crystals. When these sheets grow down to the interface, supercooling ceases. Second, the presence of the vertical ice sheets both constrains the temperatureTand salinitysto lie on the freezing curve and allows them to diffuse in the vertical. In the interfacial region, the combination of these processes generates a lateral crystal growth, which continues until a horizontal ice sheet forms. Third, because of theTandsgradients in the sea water below this ice sheet, the horizontal sheet both migrates upwards and increases in thickness. From one-dimensional theoretical models of the first two phases, we find that the heat-transfer rates are 5–10 times those calculated for classic thermal diffusion.

Challenges in Cosmetic Formulations: Appearance, Long Wear, and Comfort

MRS Bulletin ◽  
2007 ◽  
Vol 32 (10) ◽  
pp. 787-792 ◽  
Author(s):  
Prithwiraj Maitra ◽  
John Brahms
Keyword(s):  
Surface Properties ◽  
Salt Water ◽  
Flexible Substrate ◽  
Chemical Properties ◽  
Visual Appearance ◽  
Recent Advances ◽  
Eccrine Glands ◽  
Cosmetic Formulations ◽  
And Performance ◽  
The One

AbstractCosmetics are products that are designed to maintain or improve visual appearance when applied to skin. Skin is a mechanically flexible substrate that changes in chemical and surface properties during the course of the day. Sebum (an oily substance secreted by the sebaceous glands) and perspiration (a secretion of mostly salt water by the eccrine glands) as well as environmental insults work counter to the desired benefits of cosmetics on physical appearance. Recent advances in the ability to control morphology and chemical properties have led to novel materials that in turn have enabled the development of cosmetics that provide, on the one hand, a more natural look, and on the other, unique and unprecedented visual effects. Progress in understanding skin biomechanics and surface properties lead to product formulations with unprecedented wear and performance characteristics. This article reviews recent advances in the ability to control the optical, bulk, and surface properties of materials, and their application to improved cosmetic formulations.

NEUTRON–PROTON PAIRING EFFECT ON ONE-PROTON AND TWO-PROTON SEPARATION ENERGIES IN RARE-EARTH PROTON-RICH NUCLEI

2012 ◽  
Vol 21 (12) ◽  
pp. 1250100 ◽  
Author(s):  
F. HAMMACHE ◽  
N. H. ALLAL ◽  
M. FELLAH
Keyword(s):  
Wave Function ◽  
Rare Earth ◽  
Particle Number ◽  
Good Description ◽  
Mean Field ◽  
Pairing Effect ◽  
Pairing Correlations ◽  
The One ◽  
Proton Pairing ◽  
Realistic Choice

The one-proton and two-proton separation energies are studied for "ordinary" and rare-earth proton-rich nuclei by including the isovector neutron–proton (np) pairing correlations using the BCS approximation. Even–even as well as odd nuclei are considered. In the latter case, the wave function is defined using the blocked-level technique. The single-particle energies used are those of a deformed Woods–Saxon mean field. It is shown that the np isovector pairing effects on the one-proton and two-proton separation energies are non-negligible. However, the only isovector BCS approximation seems to be inadequate for a good description of these quantities when including the np pairing effects: either a particle-number projection or the inclusion of the isoscalar pairing effect seems to be necessary. Another possible improvement would be a more realistic choice of the pairing strengths.

scholarly journals Numerical Simulation of One Step Block Method for Treatment of Second Order Forced Motions in Mass-Spring Systems

2021 ◽  
pp. 1-11
Author(s):  
J. Sabo ◽  
T. Y. Kyagya ◽  
W. J. Vashawa
Keyword(s):  
Numerical Simulation ◽  
Initial Value Problems ◽  
Second Order ◽  
Block Method ◽  
Initial Value ◽  
Mathematical Problems ◽  
One Step ◽  
Grid Points ◽  
The One ◽  
Mass Spring

This paper discuss the numerical simulation of one step block method for treatment of second order forced motions in mass-spring systems of initial value problems. The one step block method has been developed with the introduction of off-mesh point at both grid and off- grid points using interpolation and collocation procedure to increase computational burden which may jeopardize the accuracy of the method in terms of error. The basic properties of the one step block method was established and numerical analysis shown that the one step block method was found to be consistent, convergent and zero-stable. The one step block method was simulated on three highly stiff mathematical problems to validate the accuracy of the block method without reduction, and obviously the results shown are more accurate over the existing method in literature.

scholarly journals Application of the Electrical (Geophysical) Method for the Identification of the Sealed Bevel in the Coastal Region of Walidia Province of el Jadida – Morocco

2018 ◽  
Vol 37 ◽  
pp. 05003
Author(s):  
H. Elfjiji ◽  
A. Boukdir ◽  
A. Zitouni
Keyword(s):  
Salt Water ◽  
Coastal Region ◽  
Upper Jurassic ◽  
The Other ◽  
List Type ◽  
Mineral Salts ◽  
Marine Invasion ◽  
Roof Structure ◽  
Other Hand ◽  
The One

The Walidia area knows a great development of agricultural, industrial, maritime activities and a very great demographic expansion. This development is accompanied by a growing demand for water. On the other hand, any intense abstraction of fresh water at a coastal aquifer capture field causes a decrease in groundwater flow and a lowering of the piezometric surface. There is therefore a danger of advancing towards the land of the saltwater bevel and salinization of groundwater which is gradually loaded into mineral salts and can reach abnormally high levels. This work deals with the application of geophysics by electrical sounding method to the in-depth study of the freshwater-salt water interface (salted bevel) on the one hand and the study of the lateral and vertical evolution of the geometry of the different aquifers. The principle of the method is, when performing an electrical survey, to research how varies, at a given point on the surface, the resistivity of the subsoil vertically. For this one executes in a same place a succession of measurements, increasing each time the dimensions of the device and thus the depth of investigation which is proportional to them. At this site, we explore a slice of ground increasingly thick and thus highlights the changes in geological constitution along the vertical. The electrical soundings were carried out with the classic Schlumberger device. The interpretation and the exploitation of the data of the electric soundings carried out made it possible to : Follow the evolution of the salted bevel roof, Draw the upstream limit (marine invasion) of salted bevel Hauterivian, on the one hand, and Valanginian and Jurassic on the other hand, Follow the roof structure of Dridrat limestone (Hauterivien) and limestones of Valanginien and Upper Jurassic, Draw the map of the marl roof of Safi (Hauterivian) constituting the impermeable substratum of Dridrat limestones.

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