Electromagnetic energy and momentum balance for surface charge distributions

1990 ◽  
Vol 58 (4) ◽  
pp. 364-366 ◽  
Author(s):  
S. Ragusa
Keyword(s):  
Surface Charge ◽  
Electromagnetic Energy ◽  
Momentum Balance ◽  
Charge Distributions ◽  
Energy And Momentum

On Microfaceting Instability of Pt(110) Under Catalytic Oxidation of Adsorbed Co

1992 ◽  
Vol 263 ◽  
Author(s):  
M. Papoular
Keyword(s):  
Catalytic Oxidation ◽  
Oxidation Reaction ◽  
Nucleation And Growth ◽  
Point Of View ◽  
Momentum Balance ◽  
Layer By Layer ◽  
Adsorption Of Co ◽  
Specific Temperature ◽  
Energy And Momentum ◽  
Sawtooth Profile

ABSTRACTAs demonstrated by recent STM [1] and LEED [2] experiments the platinum (110) surface undergoes, at carbon monoxide submonolayer coverages, a phase transition from the 1 x 2 “missing-row” (reconstructed) state to the 1 x 1(bulk-like) state under specific temperature and partial-pressure conditions. The catalytic oxidation reaction CO + 1/2 → CO2 drives a microfaceting instability [3] [4] of the Pt(110) surface which ends up in a regular sawtooth profile with a period ≈ 200 Å, along the [110] direction.We introduce the idea that the rather extensive Pt mass transport, as involved in the process, could be energetically assisted by the reaction itself. Energy and momentum-balance considerations lead us to expect an energy ≲ 0.5 eV to be transferrable to thesubstrate. This should efficiently contribute to initiating the “scraping”process that leads to the microfaceted pattern.A simple model for nucleation and growth of facets is presented (see ref. 5), yielding characteristic times of order minutes (at T = 500 K), in fair agreement with experiment.Independently of the structural/catalytic problem, adsorption of CO at submonolayer coverages on, e.g., Pt(110) might be of interest from a surfactantphysics point of view (see ref. 6 for a very recent study on layer-by-layer homoepitaxial metal growth).

scholarly journals Northern preference for terrestrial electromagnetic energy input from space weather

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
I. P. Pakhotin ◽  
I. R. Mann ◽  
K. Xie ◽  
J. K. Burchill ◽  
D. J. Knudsen
Keyword(s):  
Space Weather ◽  
Energy Input ◽  
Rotation Axis ◽  
Electromagnetic Energy ◽  
Magnetic Pole ◽  
Poynting Flux ◽  
Auroral Emissions ◽  
Energy And Momentum ◽  
Swarm Satellite ◽  
Northern And Southern Hemispheres

AbstractTerrestrial space weather involves the transfer of energy and momentum from the solar wind into geospace. Despite recently discovered seasonal asymmetries between auroral forms and the intensity of emissions between northern and southern hemispheres, seasonally averaged energy input into the ionosphere is still generally considered to be symmetric. Here we show, using Swarm satellite data, a preference for electromagnetic energy input at 450 km altitude into the northern hemisphere, on both the dayside and the nightside, when averaged over season. We propose that this is explained by the offset of the magnetic dipole away from Earth’s center. This introduces a larger separation between the magnetic pole and rotation axis in the south, creating different relative solar illumination of northern and southern auroral zones, resulting in changes to the strength of reflection of incident Alfvén waves from the ionosphere. Our study reveals an important asymmetry in seasonally averaged electromagnetic energy input to the atmosphere. Based on observed lower Poynting flux on the nightside this asymmetry may also exist for auroral emissions. Similar offsets may drive asymmetric energy input, and potentially aurora, on other planets.

Estimating Zonal Flow Contributions in Deep Water Assets From Pressure and Temperature Data

2017 ◽  
Author(s):  
A. Rashid Hasan ◽  
Rayhana N. Sohel ◽  
Xiaowei Wang
Keyword(s):  
Turbulent Flows ◽  
Deep Water ◽  
Fluid Pressure ◽  
Zonal Flow ◽  
Temperature Data ◽  
Sensitivity Analyses ◽  
Momentum Balance ◽  
Flow Profile ◽  
Flowing Fluid ◽  
Energy And Momentum

Producing hydrocarbon from deep water assets is extremely challenging and expensive. A good estimate of rates from multiple pay zones is essential for well monitoring, surveillance, and workover decisions. Such information can be gleaned from flowing fluid pressure and temperature; deep-water wells are often well instrumented that offers such data on a continuous basis. In this study a model is presented that estimates zonal flow contributions based on energy and momentum balances. Kinetic and heat energy coming from the reservoir fluid to the production tubing is accounted for in the model. The momentum balance for wellbore takes into account differing flow profile in laminar and turbulent flows. In addition, when sandface temperature data are not available, a recently developed analytical model to estimate the effect of Joule-Thompson expansion on sandface temperature was used to estimate sandface temperature from reservoir temperature. The model developed can be applied to any reservoir with multiple pay zones and is especially useful for deep-water assets where production logging is practically impossible. Available field data for multiphase flow was used to validate the model. Sensitivity analyses were performed that showed accurate temperature data is essential for the model to estimate zonal contribution accurately.

scholarly journals CONTRIBUTIONS TO THE MARINE PROPELLERS HYDRODYNAMIC DESIGN

2014 ◽  
Vol 13 (2) ◽  
pp. 41
Author(s):  
B. I. Favacho ◽  
J. R. P. Vaz ◽  
A. L. A. Mesquita
Keyword(s):  
Control Volume ◽  
Computational Cost ◽  
Momentum Balance ◽  
Marine Propellers ◽  
Energy And Momentum ◽  
Thrust And Torque ◽  
The Mathematical Model ◽  
Low Computational Cost ◽  
Bem Theory ◽  
Good Agreement

The navigation in Amazon region is very important due to the length of navigable rivers and the lack of alternative road network, as well as being a form of transportation costless for the flow of agricultural and manufacturing production. This kind of transportation present social, economic and technological importance for this region. Thus, this work objective to develop a mathematical approach for the marine propellers design, using a formulation for chord and pitch angle optimization, taken into account the equations of mass, energy and momentum balance for the theoretical calculation of thrust and torque relationships on an annular control volume, ie, the mathematical model is based in the Blade Element Momentum (BEM) theory. The proposed hydrodynamic model present low computational cost and it is easy to implement. The results are compared with classical Glauert's theory and the experimental data of the Wageningen B3-50 propeller, presenting good agreement.

Propagation of electromagnetic energy and momentum through an absorbing dielectric

1997 ◽  
Vol 55 (1) ◽  
pp. 1071-1085 ◽  
Author(s):  
R. Loudon ◽  
L. Allen ◽  
D. F. Nelson
Keyword(s):  
Electromagnetic Energy ◽  
Energy And Momentum
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