scholarly journals A Class of Quasi-Eternal Non-Markovian Pauli Channels and Their Measure

2020 ◽  
Vol 27 (04) ◽  
pp. 2050019
Author(s):  
Shrikant Utagi ◽  
Vinod N. Rao ◽  
R. Srikanth ◽  
Subhashish Banerjee
Keyword(s):  
Time Dependence ◽  
Functional Dependence ◽  
Isotropic Case ◽  
Anisotropic Case

We study a class of qubit non-Markovian general Pauli dynamical maps with multiple singularities in the generator. We discuss a few easy examples involving trigonometric or other nonmonotonic time dependence of the map, and discuss in detail the structure of channels which don’t have any trigonometric functional dependence. We demystify the concept of a singularity here, showing that it corresponds to a point where the dynamics can be regular but the map is momentarily noninvertible, and this gives a basic guideline to construct such non-invertible non-Markovian channels. Most members of the channels in the considered family are quasi-eternally non-Markovian (QENM), which is a broader class of non-Markovian channels than the eternal non-Markovian channels. Specifically, the measure of quasi-eternal non-Markovian (QENM) channels in the considered class is shown to be [Formula: see text] in the isotropic case, and about 0.96 in the anisotropic case.

A Numerical Simulation of Diffusion Experiment in Clay

2011 ◽  
Vol 322 ◽  
pp. 353-356
Author(s):  
Qing Chun Yang
Keyword(s):  
Numerical Simulation ◽  
Opalinus Clay ◽  
Isotropic Case ◽  
Diffusion Experiment ◽  
Deep Geological Repository ◽  
Transport Distance ◽  
Geological Repository ◽  
Geological Formation ◽  
Clay Formation ◽  
Anisotropic Case

Safety assessment of nuclear waste disposal in a deep geological repository requires understanding and quantifying radionuclide transport through the hosting geological formation. Determining diffusion parameters under real conditions is necessary for the performance assessment of a deep geological repository where high level wastes are placed for safety disposal. The in situ diffusion and retention (DR) experiments are designed to study the transport and retention properties of the Opalinus clay formation. In this paper, a scoping numerical simulation is performed in Opalinus Clay, The simulated results for all the traces illustrate that the maximum transport distance perpendicular to the bedding is larger in the isotropic case and those along the bedding is larger in the anisotropic case. Tracer depletion in the isotropic case is a little larger than in the anisotropic case. Deuterium and iodide can be detected in the other interval but strontium can’t. Since the length of injection interval is shorter than the transport distance, the anisotropy effect is clearly measurable. This numerical simulation of diffusion experiment aims at contributing to the optimum design of the experiment. The results of this experiment will provide additional insight into the role of diffusion anisotropy and sorption parameters for radionuclides in clays.

scholarly journals The Newtonian and MOND dynamical models of NGC 5128: Investigation of the dark matter contribution

2016 ◽  
pp. 9-20 ◽  
Author(s):  
S. Samurovic
Keyword(s):  
Dark Matter ◽  
Globular Clusters ◽  
Velocity Dispersion ◽  
Good Description ◽  
Isotropic Case ◽  
Dark Halo ◽  
Dynamical Models ◽  
Anisotropic Case ◽  
Early Type Galaxy ◽  
Centaurus A

We study the well-known nearby early-type galaxy NGC 5128 (Centaurus A) and use the sample of its globular clusters to analyze its dynamics. We study both Newtonian and MOND models assuming three cases of orbital anisotropies: isotropic case, mildly tangentially anisotropic case and the radially anisotropic case based on the literature. We find that there are two regions with different values of the velocity dispersion: interior to ~ 3 effective radii the value of the velocity dispersion is approximately 150 km s?1 , whereas beyond ~ 3 effective radii its value increases to approximately 190 km s?1 , thus implying the increase of the total cumulative mass which is indicative of the existence of dark matter there in the Newtonian approach: the mass-to-light increases from M/LB = 7 in the inner regions to M/LB = 26 in the outer regions. We found that the Navarro-Frenk-White (NFW) model with dark halo provides good description of the dynamics of NGC 5128. Using three MOND models (standard, simple and toy), we find that they all provide good fits to the velocity dispersion of NGC 5128 and that no additional dark component is needed in MOND.

Creep of Thick-Walled Orthotropic Cylinders Subject to Combined Internal and External Pressures

1976 ◽  
Vol 18 (1) ◽  
pp. 1-5 ◽  
Author(s):  
V. K. Arya ◽  
N. S. Bhatnagar
Keyword(s):  
Isotropic Case ◽  
Orthotropic Cylinder ◽  
Planar Anisotropy ◽  
Anisotropic Cylinder ◽  
Hardening Law ◽  
Creep Analysis ◽  
External Pressures ◽  
Fundamental Equations ◽  
Anisotropic Case ◽  
Elastic Strains

A creep analysis of a thick-walled anisotropic cylinder subject to combined internal and external pressures is presented. The elastic strains are also taken into account. By considering the creep rate as a function of stress multiplied by a function of time (time-hardening law), the fundamental equations for the creep of an orthotropic cylinder are obtained. These equations are solved for the particular case of planar anisotropy. A numerical example pertaining to the case of internal pressure is given and the results obtained for the anisotropic case are compared with those for the isotropic case.

Seismic parameters for media with elliptical velocity dependencies

Geophysics ◽  
1982 ◽  
Vol 47 (12) ◽  
pp. 1621-1626 ◽  
Author(s):  
Bok S. Byun
Keyword(s):  
Three Dimensional ◽  
Isotropic Case ◽  
Model Parameters ◽  
Seismic Reflection Data ◽  
Seismic Properties ◽  
Velocity Anisotropy ◽  
Reflection Data ◽  
Wave Surfaces ◽  
Ray Parameter ◽  
Anisotropic Case

The concept of wavefront curvature has been discussed extensively in the literature to relate surface seismic reflection data to subsurface geologic parameters. Developed initially for the case of homogeneous, isotropic, but arbitrarily dipping layered media, this technique has been extended to the inhomogeneous case. Now with the advent of new seismic techniques, such as vertical seismic profiling, three‐dimensional seismic methods, and shear‐wave techniques, the problem of velocity anisotropy is of growing concern to exploration seismologists. The essence of this paper is to extend the method of wavefront curvature to the “elliptically anisotropic” case in which the ray velocity varies elliptically with the direction of propagation. A fundamental feature of wave propagation in the anisotropic medium is that the direction of propagation of the disturbance (or the ray velocity direction) generally differs from that of the wavefront (or the phase velocity direction). Based on the assumption of two‐dimensional dipping layers in which velocity is “elliptically dependent” on the angle of propagation, relationships are developed between important seismic properties and model parameters. First, a relationship between the incident and refracted rays across the interface is expressed through the ray parameter. A geometrical divergence law is then developed relating the radii of the elliptical wave surfaces of the incident and refracted rays. A Dix‐type formula is finally derived which relates the normal moveout (NMO) velocity to the subsurface parameters. An example is shown to compare the radius of the wave surface and the NMO velocity for the elliptically anisotropic case with those for the equivalent isotropic case.

Experimental studies of monopole, dipole, and quadrupole acoustic logging while drilling (LWD) with scaled borehole models

Geophysics ◽  
2008 ◽  
Vol 73 (4) ◽  
pp. E133-E143 ◽  
Author(s):  
Zhenya Zhu ◽  
M. Nafi Toksöz ◽  
Rama Rao ◽  
Daniel R. Burns
Keyword(s):  
Acoustic Waves ◽  
Experimental Studies ◽  
Scale Model ◽  
Flexural Wave ◽  
Isotropic Case ◽  
Water Tank ◽  
Steel Cylinder ◽  
Natural Rock ◽  
Logging While Drilling ◽  
Anisotropic Case

We develop a 1:12 scale model logging-while-drilling (LWD) acoustic tool for laboratory measurements in borehole models to investigate the effects of tool wave modes on our ability to determine formation velocities in acoustic LWD. The scaled tool is comprised of three sections: (1) the source section, consisting of four transducers mounted on the tool body that can generate monopole, dipole, and quadrupole waves; (2) the receiver section, consisting of six sets of receivers, each containing two transducers mounted on opposite sides of the tool center line; and (3) the connector section, a threaded steel cylinder that connects the source and receiver sections tightly to simulate an LWD tool. We use four borehole models to simulate fast and slow isotropic and anisotropic formations. The slow-formation models are constructed of synthetic material ([Formula: see text] for the isotropic case and [Formula: see text] for the anisotropic case). The fast-formation models are made from natural rock samples (sandstone for the isotropic case and slate for the anisotropic case). Tool-wave characteristicswere measured in a water tank, followed by a series of experiments in the four borehole models to record monopole, dipole, and quadrupole acoustic waves when the tool was used with or without the connector. Without the connector in place, the tool measured formation arrivals that were consistent with wireline-logging predictions. With the connector in place, the coupling of the source and receiver sections resulted in strong tool waves that could mask formation arrivals. In general, the quadrupole mode more consistently provided correct formation shear-wave velocities because the tool modes propagated with higher velocities and could be separated from the formation shear arrivals. The dipole tool mode often could interfere with the formation flexural wave, especially for soft formations. By increasing the operating frequency of the source, tool waves could be eliminated and formation arrivals more easily measured in all cases. Based on these observations, it is important to choose the optimum working frequencies in LWD to reduce tool modes and allow formation shear velocities to be measured with dipole or quadrupole tools, particularly in anisotropic formations.

Inequalities for the anisotropic Poisson polytope

1995 ◽  
Vol 27 (1) ◽  
pp. 56-62 ◽  
Author(s):  
J. Mecke
Keyword(s):  
Euclidean Space ◽  
Dimensional Euclidean Space ◽  
Isotropic Case ◽  
Typical Cell ◽  
Anisotropic Case

The typical cell of a stationary Poisson hyperplane tessellation in the d-dimensional Euclidean space is called the Poisson polytope, and the cell containing the origin is called the Poisson 0-polytope. The intention of the paper is to show that the cells of the anisotropic tessellations are in some sense larger than those of the isotropic tessellations. Under the condition of equal intensities, it is proved that the moments of order n = 1, 2, … for the volume of the Poisson 0-polytope in the anisotropic case are not smaller than the corresponding moments in the isotropic case. Similar results are derived for the Poisson polytope. Finally, generalizations are mentioned.

Inequalities for the anisotropic Poisson polytope

1995 ◽  
Vol 27 (01) ◽  
pp. 56-62 ◽  
Author(s):  
J. Mecke
Keyword(s):  
Euclidean Space ◽  
Dimensional Euclidean Space ◽  
Isotropic Case ◽  
Typical Cell ◽  
Anisotropic Case

The typical cell of a stationary Poisson hyperplane tessellation in the d-dimensional Euclidean space is called the Poisson polytope, and the cell containing the origin is called the Poisson 0-polytope. The intention of the paper is to show that the cells of the anisotropic tessellations are in some sense larger than those of the isotropic tessellations. Under the condition of equal intensities, it is proved that the moments of order n = 1, 2, … for the volume of the Poisson 0-polytope in the anisotropic case are not smaller than the corresponding moments in the isotropic case. Similar results are derived for the Poisson polytope. Finally, generalizations are mentioned.

Effect of anisotropic tunneling through Coulomb barriers on the electron capture in semiconductors

1984 ◽  
Vol 62 (9) ◽  
pp. 911-914
Author(s):  
E. F. El-Wahidy
Keyword(s):  
Field Dependence ◽  
Electron Scattering ◽  
Coulomb Barrier ◽  
Adiabatic Approximation ◽  
Electron Tunneling ◽  
Capture Rate ◽  
Hot Electrons ◽  
Isotropic Case ◽  
Anisotropic Model ◽  
Anisotropic Case

The capture rate of hot electrons by negatively charged gold centres in n-Ge at T = 77 K is considered for the anisotropic model. Making use of the adiabatic approximation, the angular dependence of the electron tunneling factor through the Coulomb barrier surrounding the centre is determined. It is found that, for the anisotropic case, the tunneling factor is determined mainly by the smaller transverse effective mass of the electron. The obtained anisotropic tunneling factor is then used in studying the field dependence of the capture rate when the main mechanism of energy relaxation is due to electron scattering by acoustic phonons. A comparison with the isotropic case is given.

The O–C diagrams of minor planets − a new approach to modelling the rotation

1999 ◽  
Vol 173 ◽  
pp. 185-188
Author(s):  
Gy. Szabó ◽  
K. Sárneczky ◽  
L.L. Kiss
Keyword(s):  
Error Analysis ◽  
Time Dependence ◽  
Theoretical Work ◽  
Minor Planet ◽  
Minor Planets ◽  
New Approach ◽  
Preliminary Results ◽  
Ccd Observations

AbstractA widely used tool in studying quasi-monoperiodic processes is the O–C diagram. This paper deals with the application of this diagram in minor planet studies. The main difference between our approach and the classical O–C diagram is that we transform the epoch (=time) dependence into the geocentric longitude domain. We outline a rotation modelling using this modified O–C and illustrate the abilities with detailed error analysis. The primary assumption, that the monotonity and the shape of this diagram is (almost) independent of the geometry of the asteroids is discussed and tested. The monotonity enables an unambiguous distinction between the prograde and retrograde rotation, thus the four-fold (or in some cases the two-fold) ambiguities can be avoided. This turned out to be the main advantage of the O–C examination. As an extension to the theoretical work, we present some preliminary results on 1727 Mette based on new CCD observations.

HIV-Associated Prospective Memory Deficits Predict Functional Dependence

2007 ◽  
Author(s):  
Steven P. Woods ◽  
Jennifer E. Iudicello ◽  
Matthew S. Dawson ◽  
Lisa M. Moran ◽  
Catherine L. Carey ◽  
...  
Keyword(s):  
Prospective Memory ◽  
Functional Dependence ◽  
Memory Deficits
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