On the energy balance behind frictional ruptures

2020 ◽  
Author(s):  
Fabian Barras
Keyword(s):  
Residual Stress ◽  
Energy Balance ◽  
Fracture Energy ◽  
Energy Budget ◽  
Second Phase ◽  
Frictional Stress ◽  
Elastic Solids ◽  
Elastic Fields ◽  
Frictional Dissipation ◽  
State Models

<p>Earthquake ruptures are driven by the dynamic weakening of frictional strength along faults. This drop of frictional stress toward a residual level is at the origin of the slip-weakening model, which became a well-established framework to study seismic ruptures and their energy budget. In this framework, the part of frictional energy associated to the rupture propagation (i.e. the fracture energy) corresponds to the excess of frictional dissipation on top of the residual stress, also referred as the breakdown work<span></span>.</p><p>In this study, we test this energy partition for friction models that do not impose the magnitude of the residual stress. For example, rate-and-state models are a class of generic friction laws for which the residual stress after the rupture emerges from the interplay with the bulk elastodynamics. In this context, we simulate a frictional rupture at the interface between two linearly elastic solids and study the energy balance driving its propagation. Using dynamic fracture mechanics, we independently measure throughout the rupture the energy release rate from the bulk elastic fields and the frictional dissipation along the interface. From the comparison between these two quantities, we identify the part of interface dissipation corresponding to the fracture energy and show how the latter can be significantly smaller than the total breakdown work.</p><p>In a second phase, we test the generality of these results along another type of interface representative of mature fault zones filled with gouge.</p><p>This study shines new light on the energy budget of frictional ruptures and finds implications in the estimation of the fracture energy during earthquakes.</p>

Reflection, Refraction, and Absorption of Elastic Waves at a Frictional Interface: SH Motion

1979 ◽  
Vol 46 (3) ◽  
pp. 625-630 ◽  
Author(s):  
R. K. Miller ◽  
H. T. Tran
Keyword(s):  
Coulomb Friction ◽  
General Procedure ◽  
Frictional Stress ◽  
Elastic Solids ◽  
Sh Waves ◽  
Relative Slip ◽  
Transmission And Reflection Coefficients ◽  
Incident Plane ◽  
Frictional Interface ◽  
Transmission And Absorption

The reflection, refraction, and absorption of obliquely incident plane harmonic antiplane strain (SH) waves at a frictional interface between dissimilar semi-infinite elastic solids is investigated by an approximate analytical approach. The frictional stress at the interface is assumed to depend on the normal stress and the relative slip across the interface, but remains otherwise arbitrary throughout the analysis. General expressions are developed for the transmission and reflection coefficients, and the partitition of incident wave energy into reflection, transmission, and absorption. The special case of bonding by Coulomb friction is examined in detail as an example of application of the general procedure. An exact solution is also presented for the case of bonding by Coulomb friction, and a comparison between approximate and exact solutions provides an indication of the accuracy of the approximate method of analysis.

Digitalization of the Development of the Fuel and Energy Balance of Russia's Northern Territories

2020 ◽  
pp. 325-348
Author(s):  
Izabella Elyakova ◽  
Aleksandr Elyakov
Keyword(s):  
Control System ◽  
Energy Balance ◽  
Energy Budget ◽  
Digital Technologies ◽  
Research Practice ◽  
Production And Consumption ◽  
Entire Complex ◽  
The Republic ◽  
Northern Territories ◽  
Implementation Management

The urgency of the energy budget research practice in the Republic of Sakha (Yakutia) on settlements with software for effective formation, implementation, management, monitoring, analysis, evaluation, rapid response, and strategic management of the entire complex of the energy budget is substantiated. The chapter reveals the lack of problems of unified methodology for the development of the energy budget and the use of different fundamentals of its preparation. The necessity of using digital technologies to develop a control system for a complex network of production and consumption of fuel and energy resources is rationalized.

scholarly journals Insulin resistance in obesity: body-weight or energy balance?

2001 ◽  
Vol 171 (2) ◽  
pp. 293-298 ◽  
Author(s):  
AR Assali ◽  
A Ganor ◽  
Y Beigel ◽  
Z Shafer ◽  
T Hershcovici ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Energy Balance ◽  
Glucose Tolerance Test ◽  
Serum Levels ◽  
Tolerance Test ◽  
Negative Energy ◽  
Negative Energy Balance ◽  
Second Phase ◽  
Third Phase ◽  
Obese Subjects

Weight reduction is recommended for the treatment of subjects with insulin resistance (IR) syndrome; however, the relative importance of the decrease in body fat or the negative energy balance achieved during a hypo-energetic diet in the improvement of this metabolic syndrome is still debated. Therefore, we undertook to study their relative impact on amelioration of the metabolic abnormalities associated with IR in obese subjects. Twelve obese subjects (six males and six females, mean+/-s.d. body mass index 36.1+/-4.7 kg/m(2)) aged 38-57 years were investigated. During the first phase they were fed a hypo-energetic diet for 6 weeks (week 0-6). During the second phase, lasting 4 weeks (week 6-10) they consumed an iso-energetic diet. During the third phase (week 10-16) the subjects were put again on a hypo-energetic diet. Insulin sensitivity (SI) was assessed by an insulin-enhanced, frequently sampled i.v. glucose tolerance test with minimal model analysis. All subjects reduced weight during both hypo-energetic periods: 5.49+/-0.75 and 2.32+/-0.37%, means+/-s.e.m., P<0.005, week 0-6 and 10-16 respectively. One-third of this loss was achieved within the first week of each period. SI increased by 353+/-121 and 147+/-38% (P<0.005), means+/-s.e.m., at the end of both hypo-energetic periods (week 6 vs 0 and 16 vs 10 respectively). Two-thirds of this improvement were observed within the first week of each period (week 1 vs 0 and 11 vs 10 respectively). During the iso-energetic weight-maintaining period (week 10 vs 6), SI decreased by 43.5+/-7.9% (P<0.002). Serum levels of leptin and triglyceride followed a similar pattern, but to a lesser extent. It may be concluded that negative energy balance is more effective when compared with maintaining a stable lower weight in achieving an improvement in the metabolic parameters of the IR syndrome.

Effects of vacuum annealing treatment on microstructures and residual stress of AlSi10Mg parts produced by selective laser melting process

2016 ◽  
Vol 30 (19) ◽  
pp. 1650255 ◽  
Author(s):  
Tian Chen ◽  
Linzhi Wang ◽  
Sheng Tan
Keyword(s):  
Residual Stress ◽  
Tensile Strength ◽  
Selective Laser Melting ◽  
Vacuum Annealing ◽  
Annealing Treatment ◽  
Melting Process ◽  
Second Phase ◽  
Laser Melting ◽  
Heat Treated ◽  
Before And After

Selective laser melting (SLM)-fabricated AlSi10Mg parts were heat-treated under vacuum to eliminate the residual stress. Microstructure evolutions and tensile properties of the SLM-fabricated parts before and after vacuum annealing treatment were studied. The results show that the crystalline structure of SLM-fabricated AlSi10Mg part was not modified after the vacuum annealing treatment. Additionally, the grain refinement had occurred after the vacuum annealing treatment. Moreover, with increasing of the vacuum annealing time, the second phase increased and transformed to spheroidization and coarsening. The SLM-produced parts after vacuum annealing at 300[Formula: see text]C for 2 h had the maximum ultimate tensile strength (UTS), yield strength (YS) and elongation, while the elastic modulus decreased significantly. In addition, the tensile residual stress was found in the as-fabricated AlSi10Mg samples by the microindentation method.

scholarly journals A comparison of eddy-covariance and large aperture scintillometer measurements with respect to the energy balance closure problem

2011 ◽  
Vol 15 (4) ◽  
pp. 1291-1306 ◽  
Author(s):  
S. M. Liu ◽  
Z. W. Xu ◽  
W. Z. Wang ◽  
Z. Z. Jia ◽  
M. J. Zhu ◽  
...  
Keyword(s):  
Heat Flux ◽  
Energy Balance ◽  
Eddy Covariance ◽  
Energy Budget ◽  
Seasonal Variations ◽  
Heat Fluxes ◽  
Sensible Heat ◽  
Source Areas ◽  
Large Aperture ◽  
Large Aperture Scintillometer

Abstract. We analyzed the seasonal variations of energy balance components over three different surfaces: irrigated cropland (Yingke, YK), alpine meadow (A'rou, AR), and spruce forest (Guantan, GT). The energy balance components were measured using eddy covariance (EC) systems and a large aperture scintillometer (LAS) in the Heihe River Basin, China, in 2008 and 2009. We also determined the source areas of the EC and LAS measurements with a footprint model for each site and discussed the differences between the sensible heat fluxes measured with EC and LAS at AR. The results show that the main EC source areas were within a radius of 250 m at all of the sites. The main source area for the LAS (with a path length of 2390 m) stretched along a path line approximately 2000 m long and 700 m wide. The surface characteristics in the source areas changed with the season at each site, and there were characteristic seasonal variations in the energy balance components at all of the sites. The sensible heat flux was the main term of the energy budget during the dormant season. During the growing season, however, the latent heat flux dominated the energy budget, and an obvious "oasis effect" was observed at YK. The sensible heat fluxes measured by LAS at AR were larger than those measured by EC at the same site. This difference seems to be caused by the so-called energy imbalance phenomenon, the heterogeneity of the underlying surfaces, and the difference between the source areas of the LAS and EC measurements.

scholarly journals Analysis of the energy balance closure over a FLUXNET boreal forest in Finland

2010 ◽  
Vol 7 (3) ◽  
pp. 2683-2707
Author(s):  
J. M. Sánchez ◽  
V. Caselles ◽  
E. M. Rubio
Keyword(s):  
Energy Balance ◽  
Boreal Forest ◽  
Energy Budget ◽  
Friction Velocity ◽  
Average Energy ◽  
Surface Energy Budget ◽  
Forest Site ◽  
Energy Balance Closure ◽  
Hourly Data ◽  
Averaging Time

Abstract. The imbalance in the surface energy budget, when using eddy-covariance techniques to measure turbulent fluxes, is still an unresolved problem. Important progresses have been reported in recent years identifying potential reasons for this lack of energy balance closure. In this paper we focus on the data collected in a FLUXNET boreal forest site in Sodankylä, Finland. Using one month half-hourly data, an average Energy Balance Ratio (EBR) of 0.72 is obtained. The inclusion of the heat storage terms in the energy budget yields an improvement of about 6% in the total closure. The sensitivity of the energy balance closure to the turbulence intensity is analysed in terms of the friction velocity, and atmospheric stability/instability conditions. Significant better closure is obtained for high values of the friction velocity and unstable conditions. The mismatch in variable footprints for different fluxes is checked by analysing the dependence of the closure on wind direction. The inhomogeneities of the emplacement surrounding the flux tower induce a critical decrease in the EBR of up to 30% for specific wind directions. After filtering all unfavourable conditions, EBR=0.94. This is a reasonable good result for the energy balance closure. However there is still a 6% of the available energy unaccounted. Part of this remaining imbalance could be justified as the impossibility of the 30 min averaging time to capture the low frequency flux contributions, since the closure is improved by a 5% when the averaging time is expanded to 2 h.

scholarly journals Influência da Superfície no Balanço de Energia e na Intensidade da Precipitação Urbana (Influence of the Surface Energy Balance and Intensity Urban Rainfall)

2011 ◽  
Vol 3 (3) ◽  
pp. 204
Author(s):  
Taciana Lima Araujo ◽  
Enio Pereira Souza
Keyword(s):  
Energy Balance ◽  
Surface Energy ◽  
Energy Budget ◽  
Surface Energy Balance ◽  
Atmospheric Modeling ◽  
Radiation Budget ◽  
Surface Processes ◽  
Regional Atmospheric Modeling System ◽  
Regional Atmospheric Modeling ◽  
The City

O objetivo deste trabalho é estudar, através da modelagem numérica da atmosfera, os processos de superfície que determinam o saldo de radiação e a precipitação na zona urbana da cidade do Recife-PE. O modelo utilizado é o Brazilian developments on the Regional Atmospheric Modeling System - BRAMS. Uma melhora na representação dos processos de superfície em áreas urbanas foi obtida através do acoplamento entre o modelo BRAMS e um esquema específico para a representação da dinâmica urbana, o esquema Town Energy Budget - TEB. Foram realizados dois experimentos para testar a sensibilidade do modelo à representação da cidade. A consideração da superfície urbana aumenta o saldo de radiação sobre a cidade porque diminui o albedo da superfície e diminui a radiação de onda longa emitida. A influência das regiões urbanas nesses processos altera os fluxos de energia em superfície e, causa aumento da precipitação.Palavras-chave: BRAMS, região urbana, saldo de radiação.  Influence of the Surface Energy Balance and Intensity Urban Rainfall ABSTRACTThe objective of this work is to study the surface processes that determine the radiation budget and the precipitation at the urban area of the city of Recife-PE. The model used is the Brazilian developments on the Regional Atmospheric Modeling System - BRAMS. An improvement in the representation of the surface processes in urban areas was achieved through the coupling of the BRAMS model with a scheme suitable to representing the urban dynamics, the Town Energy Budget - TEB. Two experiments were run to test the model’s sensitivity to the city representation. The consideration of the urban surface increases the radiation budget over the city because it diminishes the surface albedo and the upcoming long wave radiation. The influence of the urban area alters the surface energy fluxes and increases the precipitation.Keywords: BRAMS, urban region, radiation budget

Radiation and Climate

2017 ◽  
Author(s):  
Kelly Chance ◽  
Randall V. Martin
Keyword(s):  
Energy Balance ◽  
Solar Radiation ◽  
Optical Depth ◽  
Energy Budget ◽  
Radiative Forcing ◽  
Global Climate ◽  
Layer Model ◽  
Long Wave ◽  
Dependent Absorption ◽  
Long Wave Infrared

Global climate is controlled by an energy balance between incoming solar radiation and outgoing terrestrial radiation. An energy balance is first developed using a simple one-layer model of the atmosphere and then made more realistic by distributing the atmospheric optical depth smoothly in a Gray Atmosphere Model. Wavelength-specific and altitude-dependent absorption and emission for the ultraviolet through long-wave infrared are described. Knowledge is combined into an overall Earth energy budget. The sensitivity of the climate to radiative forcing is examined.

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