Search results for "inversion"

External Noise Effects in Silicon MOS Inversion Layer

2013

The effect of the addition of an external source of correlated noise on the electron transport in silicon MOS inversion layer, driven by a static electric field, has been investigated. The electron dynamics is simulated by a Monte Carlo procedure which takes into account non-polar optical and acoustic phonons. In our modelling of the quasi-two-dimensional electron gas, the potential profile, perpendicular to the MOS structure, is assumed to follow the triangular potential approximation. We calculate the changes in both the autocorrelation function and the spectral density of the velocity fluctuations, at different values of noise amplitude and correlation time. The findings indicate that, t…

Simultaneous time-optimal control of the inversion of two spin-12particles

2010

We analyze the simultaneous time-optimal control of two-spin systems. The two noncoupled spins, which differ in the value of their chemical offsets, are controlled by the same magnetic fields. Using an appropriate rotating frame, we restrict the study to the case of opposite shifts. We then show that the optimal solution of the inversion problem in a rotating frame is composed of a pulse sequence of maximum intensity and is similar to the optimal solution for inverting only one spin by using a nonresonant control field in the laboratory frame. An example is implemented experimentally using nuclear magnetic resonance techniques.

Discrete-valued-pulse optimal control algorithms: Application to spin systems

2015

International audience; This article is aimed at extending the framework of optimal control techniques to the situation where the control field values are restricted to a finite set. We propose generalizations of the standard GRAPE algorithm suited to this constraint. We test the validity and the efficiency of this approach for the inversion of an inhomogeneous ensemble of spin systems with different offset frequencies. It is shown that a remarkable efficiency can be achieved even for a very limited number of discrete values. Some applications in nuclear magnetic resonance are discussed.

Time-domain-induced polarization: Full-decay forward modeling and 1D laterally constrained inversion of Cole-Cole parameters

2012

Time-domain-induced polarization has significantly broadenedits field of reference during the last decade, from mineralexploration to environmental geophysics, e.g., for clay and peatidentification and landfill characterization. Though, insufficientmodeling tools have hitherto limited the use of time-domaininducedpolarization for wider purposes. For these reasons, anew forward code and inversion algorithm have been developedusing the full-time decay of the induced polarization response,together with an accurate description of the transmitter waveformand of the receiver transfer function, to reconstruct thedistribution of the Cole-Cole parameters of the earth. The accuratemodeling of the tra…

Partially Implicit Runge-Kutta Methods for Wave-Like Equations

2014

Runge-Kutta methods are used to integrate in time systems of differential equations. Implicit methods are designed to overcome numerical instabilities appearing during the evolution of a system of equations. We will present partially implicit Runge-Kutta methods for a particular structure of equations, generalization of a wave equation; the partially implicit term refers to this structure, where the implicit term appears only in a subset of the system of equations. These methods do not require any inversion of operators and the computational costs are similar to those of explicit Runge-Kutta methods. Partially implicit Runge-Kutta methods are derived up to third-order of convergence. We ana…

Temperature Inversion Breakup with Impacts on Air Quality in Urban Valleys Influenced by Topographic Shading

2015

AbstractUrban valleys can experience serious air pollution problems as a combined result of their limited ventilation and the high emission of pollutants from the urban areas. Idealized simulations were analyzed to elucidate the breakup of an inversion layer in urban valleys subject to a strong low-level temperature inversion and topographic effects on surface heating such as topographic shading, as well as the associated air pollution transport mechanisms. The results indicate that the presence and evolution in time of the inversion layer and its interplay with an urban heat island within the valley strongly influence the venting of pollutants out of urban valleys. Three mechanisms of air …

A rank theorem for analytic maps between power series spaces

1994

Three-dimensional inversion mode rendering in molar pregnancy

2008

(In)Efficiencies in Latin American ETFs

2017

Este estudio evalúa empíricamente la eficiencia en la valoración de varios ETFs latinoamericanos, expresada en desviaciones de sus precios de mercado frente a los valores liquidativos subyacentes. Se cuantifican tales ineficiencias y se implementa una estrategia de negociación verificada por regresiones basadas en el CAPM y el Modelo Fama-French. Los resultados discrepan con la Hipótesis de los Mercados Eficientes y son mejor explicados por aspectos de las finanzas comportamentales. Finalmente, se examina cómo las desviaciones influyen sobre la decisión de creación o redención de ETFs, mediante un análisis de regresión logística. Los resultados evidencian que los participantes autorizados r…

Hyplets - Multi Exception Level Kernel towards Linux RTOS

2018

This paper presents the concept of a Multi-Exception level operating system. We add a hypervisor awareness to the Linux kernel and execute code in hyp exception level. We do that through the use of Hyplets. Hyplets are an innovative way to code interrupt service routines under ARM. Hyplets provide high performance, security, running time predictability, an RPC mechanism and a possible solution for the priority inversion problem. Hyplets uses special features of ARM8va hypervisor memory architecture.