scholarly journals Factors controlling the sequence of asperity failures in a fault model

2018 ◽  
Author(s):  
Emanuele Lorenzano ◽  
Michele Dragoni
Keyword(s):  
Degrees Of Freedom ◽  
Seismic Event ◽  
Frictional Resistance ◽  
Fault Model ◽  
Seismic Events ◽  
Viscoelastic Relaxation ◽  
Viscoelastic Deformation ◽  
Tectonic Loading ◽  
The Difference ◽  
Three Degrees Of Freedom

Abstract. We consider a fault with two asperities embedded in a shear zone subject to a uniform strain rate owing to tectonic loading. The static stress field generated by seismic events undergoes viscoelastic relaxation as a consequence of the rheological properties of the asthenosphere. We treat the fault as a dynamical system whose basic elements are the asperities. The system has three degrees of freedom: the slip deficits of the asperities and the variation of their difference due to viscoelastic deformation. The dynamics of the system can be described in terms of one sticking mode and three slipping modes, for which we provide analytical solutions. We discuss how the stress state at the beginning of the interseismic interval preceding a seismic event controls the sequence of slipping modes during the event. We focus on the events associated with the separate (consecutive) slips of the asperities and investigate how they are affected by the seismic efficiency of the fault, by the difference in frictional resistance of the asperities and by the intensity of coupling between the asperities.

scholarly journals Complex interplay between stress perturbations and viscoelastic relaxation in a two-asperity fault model

2018 ◽  
Vol 25 (1) ◽  
pp. 251-265
Author(s):  
Emanuele Lorenzano ◽  
Michele Dragoni
Keyword(s):  
Dynamical System ◽  
Degrees Of Freedom ◽  
Discrete Dynamical System ◽  
Fault Model ◽  
Viscoelastic Relaxation ◽  
Simple Correlation ◽  
Complex Interplay ◽  
Viscoelastic Deformation ◽  
Single Asperity ◽  
Tectonic Loading

Abstract. We consider a plane fault with two asperities embedded in a shear zone, subject to a uniform strain rate owing to tectonic loading. After an earthquake, the static stress field is relaxed by viscoelastic deformation in the asthenosphere. We treat the fault as a discrete dynamical system with 3 degrees of freedom: the slip deficits of the asperities and the variation of their difference due to viscoelastic deformation. The evolution of the fault is described in terms of inter-seismic intervals and slip episodes, which may involve the slip of a single asperity or both. We consider the effect of stress transfers connected to earthquakes produced by neighbouring faults. The perturbation alters the slip deficits of both asperities and the stress redistribution on the fault associated with viscoelastic relaxation. The interplay between the stress perturbation and the viscoelastic relaxation significantly complicates the evolution of the fault and its seismic activity. We show that the presence of viscoelastic relaxation prevents any simple correlation between the change of Coulomb stresses on the asperities and the anticipation or delay of their failures. As an application, we study the effects of the 1999 Hector Mine, California, earthquake on the post-seismic evolution of the fault that generated the 1992 Landers, California, earthquake, which we model as a two-mode event associated with the consecutive failure of two asperities.

scholarly journals Complex interplay between stress perturbations and viscoelastic relaxation in a two-asperity fault model

2017 ◽  
Author(s):  
Emanuele Lorenzano ◽  
Michele Dragoni
Keyword(s):  
Degrees Of Freedom ◽  
Discrete Dynamical System ◽  
The State ◽  
Viscoelastic Relaxation ◽  
State Variables ◽  
Simple Correlation ◽  
Complex Interplay ◽  
Viscoelastic Deformation ◽  
Tectonic Loading ◽  
Three Degrees Of Freedom

Abstract. We consider a plane fault with two asperities embedded in a shear zone, subject to a uniform strain rate owing to tectonic loading. After an earthquake, the static stress field is relaxed by viscoelastic deformation. We treat the fault as a discrete dynamical system with three degrees of freedom: the slip deficits of the asperities and the variation of their difference due to viscoelastic deformation. The dynamics of the system is described in terms of one sticking mode and three slipping modes. We consider the effect of stress transfers connected to earthquakes produced by neighbouring faults. The perturbation is studied in terms of a vector in the state space, whose components are the changes in the state variables of the system. The interplay between the stress perturbation and the viscoelastic relaxation significantly complicates the evolution of the fault and its seismic activity. We show that the presence of viscoelastic relaxation prevents any simple correlation between the change of Coulomb stresses on the asperities and the anticipation or delay of their failures. As an application, we study the effects of the 1999 Hector Mine, California, earthquake on the post-seismic evolution of the fault that generated the 1992 Landers, California, earthquake, which we model as a two-mode event associated with the consecutive failure of two asperities.

Analysis of a 3-DOF Micro-Positioning Stage

2014 ◽  
Vol 620 ◽  
pp. 234-239 ◽  
Author(s):  
De De Zhai ◽  
Shi Xun Fan ◽  
Da Peng Fan
Keyword(s):  
Theoretical Basis ◽  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Theory Analysis ◽  
Stage Design ◽  
Flexure Hinges ◽  
Positioning Stage ◽  
Effect Curve ◽  
The Difference ◽  
Three Degrees Of Freedom

Firstly a three degrees of freedom micro-positioning stage constructed by flexure hinges is designed, and the simplified model of the stage is established. Secondly, the stiffness of the stage along X, Y direction or around Z direction is deduced by structural mechanics. The difference between finite element method and theory value is less than 7%, so it shows the theory analysis is feasible, further more, stress of the moving stage is analyzed, and the effect curve of the key parameters to the stiffness and stress is obtained. It can be concluded that the stiffness and stress mainly related with the flexure hinge length L and width t, thus it provide a theoretical basis for three-dimensional micro-positioning stage design.

scholarly journals Derivation of instantaneous unit hydrographs using linear reservoir models

2021 ◽  
Author(s):  
Parjang Monajemi ◽  
Setareh Khaleghi ◽  
Shahrzad Maleki
Keyword(s):  
Linear Function ◽  
Degrees Of Freedom ◽  
Weighting Coefficient ◽  
Reservoir Models ◽  
Proposed Model ◽  
The Difference ◽  
Linear Differential ◽  
Linear Reservoir ◽  
Unit Hydrographs ◽  
Three Degrees Of Freedom

Abstract In this research, a new conceptual model for producing instantaneous unit hydrographs (IUHs) is introduced by a linear combination of the Nash model, which assumes that the discharge from a reservoir is a linear function of its storage, and a model called inter-connected linear reservoir model (ICLRM), which assumes that the discharge from a reservoir is a linear function of the difference of its storage and its adjacent downstream reservoir. By employing these assumptions, a system of first-order linear differential equations with three degrees of freedom (storage coefficient, number of reservoirs, and weighting coefficient) is obtained as the governing equation for the proposed model. This model may be considered as the general form of the two models and is therefore capable of simulating IUHs laying between these two models. To show the capabilities of the model, linear and curvilinear soil conservation service (SCS) hydrographs are simulated using dimensionless hydrographs obtained by this model. Moreover, several real hydrographs were simulated by the proposed model and compared with hydrographs obtained by Nash, ICLRM, and SCS models. The results show that the model yields more accurate results compared to other studied models and may be considered as a new model for simulating IUHs.

On the Use of Quantum Thermal Bath in Unimolecular Fragmentation Simulations

2019 ◽  
Author(s):  
Riccardo Spezia ◽  
Hichem Dammak
Keyword(s):  
Degrees Of Freedom ◽  
Molecular Simulations ◽  
Zero Point ◽  
Thermal Bath ◽  
Unimolecular Dissociation ◽  
Point Energy ◽  
Rotational Degrees Of Freedom ◽  
The Difference ◽  
Nuclear Effects

<div> <div> <div> <p>In the present work we have investigated the possibility of using the Quantum Thermal Bath (QTB) method in molecular simulations of unimolecular dissociation processes. Notably, QTB is aimed in introducing quantum nuclear effects with a com- putational time which is basically the same as in newtonian simulations. At this end we have considered the model fragmentation of CH4 for which an analytical function is present in the literature. Moreover, based on the same model a microcanonical algorithm which monitor zero-point energy of products, and eventually modifies tra- jectories, was recently proposed. We have thus compared classical and quantum rate constant with these different models. QTB seems to correctly reproduce some quantum features, in particular the difference between classical and quantum activation energies, making it a promising method to study unimolecular fragmentation of much complex systems with molecular simulations. The role of QTB thermostat on rotational degrees of freedom is also analyzed and discussed. </p> </div> </div> </div>

scholarly journals Active Disturbance Rejection for a Three Degrees of Freedom Gyroscope

2018 ◽  
Vol 51 (13) ◽  
pp. 372-377 ◽  
Author(s):  
Juan E. Andrade García ◽  
Alejandra Ferreira de Loza ◽  
Luis T. Aguilar ◽  
Ramón I. Verdés
Keyword(s):  
Disturbance Rejection ◽  
Degrees Of Freedom ◽  
Active Disturbance Rejection ◽  
Three Degrees Of Freedom

scholarly journals Cyclic Deformation of Microcantilevers Using In-Situ Micromanipulation

2021 ◽  
Author(s):  
A. H. S. Iyer ◽  
M. H. Colliander
Keyword(s):  
Degrees Of Freedom ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Structural Components ◽  
Cyclic Testing ◽  
Phase Boundaries ◽  
Bulk Specimen ◽  
Arbitrary Position ◽  
Three Degrees Of Freedom

Abstract Background The trend in miniaturisation of structural components and continuous development of more advanced crystal plasticity models point towards the need for understanding cyclic properties of engineering materials at the microscale. Though the technology of focused ion beam milling enables the preparation of micron-sized samples for mechanical testing using nanoindenters, much of the focus has been on monotonic testing since the limited 1D motion of nanoindenters imposes restrictions on both sample preparation and cyclic testing. Objective/Methods In this work, we present an approach for cyclic microcantilever bending using a micromanipulator setup having three degrees of freedom, thereby offering more flexibility. Results The method has been demonstrated and validated by cyclic bending of Alloy 718plus microcantilevers prepared on a bulk specimen. The experiments reveal that this method is reliable and produces results that are comparable to a nanoindenter setup. Conclusions Due to the flexibility of the method, it offers straightforward testing of cantilevers manufactured at arbitrary position on bulk samples with fully reversed plastic deformation. Specific microstructural features, e.g., selected orientations, grain boundaries, phase boundaries etc., can therefore be easily targeted.

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