Nonphysical Fields Research Articles

Unified Formulation of Leapfrog Complying Divergence Implicit FDTD Method for Lossy Media

The leapfrog alternating direction implicit finite-difference time-domain (ADI-FDTD) method for lossy media has been found to suffer from the non-physical field leakage problem in the non-penetrable structures, which gives rise to inaccuracies in modelling lossy media during scattering analyses. To address such problem, in this paper, we propose a unified formulation of leapfrog complying-divergence implicit (CDI)-FDTD method for lossy media without field leakage problem. Several different lossy schemes to incorporate the conductivity terms of lossy media, including exponential time differencing, averaging and forward-forward schemes are integrated into a unified formulation. The proposed leapfrog CDI-FDTD method not only resolves the problem of field leakage but also has complying divergence. Moreover, since the implicit update procedures in the proposed formulation are in the fundamental form with matrix-operator-free right-hand sides, the floating-point operations (flops) are fewer than that of the conventional leapfrog ADI-FDTD formulation for lossy media. Numerical results are given to demonstrate the advantages of the proposed method over the leapfrog ADI-FDTD method in accuracy, efficiency, complying divergence and resolving the field leakage problem for lossy media.

Quantum states and their back-reacted geometries in 2D dilaton gravity

Within the Russo-Susskind-Thorlacius (RST) two-dimensional model that includes a scalar (dilaton) field we address the important question of how the classical black hole geometry is modified in a semiclassical gravitational theory. It is the principle goal of this paper to analyze what is the back-reacted geometry that corresponds to a given quantum state. The story is shown to be dramatically different for the Hartle-Hawking state (HH) and for the Boulware state. In the HH case the back-reacted geometry is a modification of the classical black hole metric that still has a smooth horizon with a regular curvature. On the other hand, for the Boulware state the classical horizon is replaced by a throat in which the $(tt)$ component of the metric (while nonzero) is extremely small. The value of the metric at the throat is bounded by the inverse of the classical black hole entropy. On the other side of the throat the spacetime is ended at a null singularity. More generally, we identify a family of quantum states and their respective back-reacted geometries. We also identify a certain duality in the space of states. Finally, we study a hybrid setup where both physical and nonphysical fields, such as the ghosts, could be present. We suggest that it is natural to associate ghosts with the Boulware state, while the physical fields can be in any quantum state. In particular, if the physical fields are in the HH state, then the corresponding semiclassical geometry is horizonless. Depending on the balance between the number of physical fields and ghosts, it generically has a throat that may join with another asymptotically flat region on the other side of the throat.

The Mind and its Procedure in Buddhism

The mind (nāma) and matter (rūpa) are the two great constituents of the beings. Nāma refers to the mental phenomena of the four aggregates vedanā, saññā, saṅkhāra and vijññān. The mind is a formless, shapeless, non-physical field that functions to store, perceive, and analyze information. It originates when the six senses; eye, ear, nose, tongue, skin and the mind get contact with their corresponding objects; form, sound, smell, taste, touch and mental constituents respectively. The mind and the brain are completely different entities. The mind is an agent that carries the seed to have the next life. The rūpa is a physical phenomenon. It is the material form of the body and of the eternal world. Earth (prithivi dhātu), water (apo dhātu), fire (tejo dhātu) and wind (vayo dhātu) element are the four fundamental elements in our body and the outer world. Mental phenomenon and physical phenomenon are different but dependents on each other. The objective of this article is to examine the mind and its procedure. Both original texts of Buddhism have been used as primary sources and published books and articles have been used as secondary sources of information. Life is all about the continuous process of mental aggregates and physical matter. The mind links the earlier life to the present and for the future. Suffering and happiness are the two major state of a mind. The worldly mind is the source of suffering whereas the enlightened mind is the source of endless happiness. Buddhism is a way of achieving endless happiness i.e nirvana through the practice of the noble path.

EPISTIMOLOGI MANAJEMEN DI ERA KEMAJUAN ISLAM

AbstractIn the context of Islam, science is the beginning of human substance in building world civilization. Islamic epistemology has similarities with the term science in Western epistemology. Just as science in Western epistemology is distinguished from knowledge, science in Islamic epistemology is distinguished from opinion (ra'y). Science is not arbitrary knowledge or just opinion, but knowledge that has been tested for truth. The understanding of science is actually not much different from science, only science is limited to physical or sensory fields, science goes beyond it in non-physical fields such as metaphysics. Historical metamorphosis is added to analysis and management knowledge. Muslim philosophers are used as a basic reference as the core paradigm of management based on humanity and human patterns. Keywords: Epistemology, Muslim Philosophers, Islamic Management Orientation

A plane wave least squares method for the Maxwell equations in anisotropic media

In this paper, we first consider the time-harmonic Maxwell equations with Dirichlet boundary conditions in three-dimensional anisotropic media, where the coefficients of the equations are general symmetric positive definite matrices. By using scaling transformations and coordinate transformations, we build the desired stability estimates between the original electric field and the transformed nonphysical field on the condition number of the anisotropic coefficient matrix. More importantly, we prove that the resulting approximate solutions generated by plane wave least squares (PWLS) methods have the nearly optimal L2 error estimates with respect to the condition number of the coefficient matrix. Finally, numerical results verify the validity of the theoretical results, and the comparisons between the proposed PWLS method and the existing PWDG method are also provided.

Systems featuring chain structures – a generalized Bond Graph modelling

ABSTRACTThe study presents power flow modelling for dynamic systems featuring chain structures. For this purpose, the Bond Graph method is particularly suitable. This tool describes engineering systems in different fields via domain-independent graphical representation using general dynamic modelling for any physical system. Even repetitive constructions called chains can be modelled. This paper aims for power flow based dynamical models of serial type chain structures. Further graphical systematization identifies four basic scalar segments which again correlate with four general vectorial total model structures. Examples and general algorithms, to obtain the scalar segment model and the vectorial overall model, support the proposed modeling. The main vectorial modelling element is identified as a relative coordinate transformation. The approach includes usage for open and closed chains plus rings of ring structures. It aims at universal usage independent of serial chain structure type, application domain or software tool. Moreover, it can be used beneficially in various non-physical fields.

Consistency Requirements for Integral Representations of Green’s Functions—Part II: An Erroneous Representation

The two requirements set forth in Part I of this paper are used to demonstrate the inadequacy of a recently proposed Green’s function for a material half-space. It is shown that the construction carried out with respect to the wavenumber normal to the interface results not only in an incomplete representation but also in nonphysical fields in the conducting medium. By comparing with the Sommerfeld integral representation, which was shown to be complete and exact in Part I, it is demonstrated that the so-constructed Green’s function with respect to the vertical wavenumber: 1) has an error in the main contribution (arising from the primary branch cut) and 2) lacks the key ingredients of a surface wave and an additional branch cut contribution in the representation.

Dispersion optimised plane wave sources for scattering analysis with integral based high order finite difference time domain methods

The implementation of plane wave incidence using the total-field/scattered-field (TFSF) formulation for a three-dimensional finite volumes-based, extended-stencil finite-difference time-domain (FV24) algorithm is presented. This achievement required designing an auxiliary one-dimensional grid with the characteristics of (i) co-located electric field components uniformly spaced from co-located magnetic field components, (ii) grid spacing that dynamically changes with desired angles of propagation to eliminate the need for field interpolations when mapping the plane wave to the main grid, (iii) update equations that precisely match the numerical dispersion characteristics of the main FV24 algorithm, and (iv) auxiliary to main grid field mapping that encompasses six parallel surfaces along the TFSF boundary to satisfy the extended cell nature of the main FV24 algorithm. The resulting non-physical field leakage into the scattered-field region is observed to be independent of angle of incidence and has a −300 dB noise floor. This technique extends the high-order FV24 capabilities to include accurate and efficient simulations of electrically large scatterers using relatively low grid densities, bringing this capability to today's desk-side workstations.

Non-physical finite element method: Multiple material discontinuities

The theory proposed in the paper provides a new approach for the modelling of multiple material discontinuities. The scope of this work is restricted to numerical methods and in particular an approach that utilises the benefits of traditional continuous finite element approximations but enhanced with an increased capacity for handling material discontinuities. The approach is founded on transport forms of the governing conservation laws describing discontinuous physics by means of bespoke moving control volumes and the non-physical field concept. The theory is demonstrated through its application to steady-state and transient flyer impact-plate problems for which analytical results are available.

Non-physical finite element modelling of high speed normal crushing of cellular materials

This work presents a new FE based methodology for numerical simulation of shock like behaviour in high speed crushing of metallic cellular materials. This recently developed numerical technique is called the non-physical finite element method. The approach is based on integral transport forms of the governing conservation laws and the concept of non-physical variable. With the non-physical variable concept each conservation law gives rise to a non-physical field. Unfortunately this results in a doubling of the number of transport equations and the number of field variables. However, non-physical variables can be shown to possess limiting continuity at any discontinuity in the physical fields. Another feature of the formulation is the presence of a non-physical source term at a discontinuity whose strength is related to the magnitude of the discontinuity in the physical field. One benefit of the approach is the precise annihilation of discontinuous behaviour from the governing finite element equations. Hence, classical continuous finite element approximations can be used with high accuracy to solve the resulting system of equations. The methodology is demonstrated through application to three different models of 1-D in-plane high-velocity impact crushing of a cellular Taylor bar, where numerical results are found to be in excellent correspondence to predictions from analytical models. The present work belongs to the category of finite element based shock capturing techniques.

On the field leakage of the leapfrog ADI‐FDTD method for nonpenetrable targets

ABSTRACTThis letter investigates the field leakage of the leapfrog alternating‐direction‐implicit finite‐difference time‐domain (ADI‐FDTD) method for nonpenetrable targets. The update equation for lossy media using time‐averaging scheme is reviewed. Investigation reveals that the leapfrog ADI‐FDTD method has substantial nonphysical field leakage within the target. To overcome the field leakage, a simple approach is proposed. Numerical results are presented to validate the proposed approach. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1401–1405, 2014

METAPHORIZED MOTION IN ENGLISH

Physical motion is frequently metaphorized to express abstract concepts or states of affairs. This article aims to explore the phenomena of metaphorized motion in English. Example sentences drawn from English dictionaries are furnished to attest and examine the workings of metaphorized motion in various non-physical fields. One interesting finding is that two contrasting metaphorical vehicles-namely the moving entity and the stationary bounded space-apply to a variety of non-spatial fields. The two recurring contradictory vehicles suggest that there are limits to the systematicity and coherence of conventional metaphors of motion in English.

A smoothed boundary condition for reducing nonphysical field effects

In this paper, we examine the problem associated with abruptly mixing boundary conditions in the context of a two dimensional semiconductor device simulator. Explicitly, this paper addresses the transition between an ohmic-type Dirichlet condition and a passivated Neumann boundary. In the traditional setting, the details of the transition between the two boundary types are not addressed and an abrupt transition is assumed. Subsequently, the calculated observables (most notably the potential) exhibit discontinuous derivatives near the surface at the point where the boundary type switches. This paper proposes an alternative condition which models the progression between the two boundary types through the use of a finite length, smoothed boundary whereby the numerical discontinuities are eliminated. The physical and mathematical basis for this smoothed boundary condition is discussed and examples of the technique's implementation given. It is found that the proposed boundary condition is numerically efficient and can be implemented in pre-existing device simulators with relative ease.

A comment on boundary conditions of bosonic Lagrange multipliers at finite temperature

The partition function defined in the usual way is a gauge-dependent quantity. However, the ansatz of Bernard and Gross et al leaves it gauge invariant. We use this ansatz for the partition function to show that Lagrange multipliers (non-physical bosonic fields) are not restricted to satisfying any boundary conditions in the path integral at finite temperature. We take a quantum mechanical model to illustrate that boundary conditions satisfied by non-physical fields depend on the choice of `gauge'.Resumo. Pela definição usual da Função de Partição, esta é uma quantidade que depende da escolha de calibre. Entretanto, Bernard e Gross et al. propuseram um ansatz no qual a Função de Partição é independente do calibre. Utilizamos este ansatz para a Função de Partição, para mostrar que os multiplicadores de Lagrange (campos bosônicos não-físicos) não são obrigados a satisfazerem condições de contorno na integral funcional a temperatura finita. Consideramos um modelo em Mecânica Quântica para ilustrar, que as condições de contorno satisfeitas pelos campos não - físicos nas integrais funcionais a temperatura finita, representam uma escolha de calibre.

Gaugeless reduction of gravity and the evolution of the Universe.

The physical phase space of Einstein gravity with the Dirac-Arnowitt-Deser-Misner metric is constructed without using a gauge-fixing condition by explicitly resolving the constraints for nonphysical fields. As a result, from the reduced Einstein action we get a new energy-momentum tensor for independent dynamical fields. The corresponding energy and time are in direct analogy with the ``spectral energy'' and ``observable time'' for a relativistic particle. We discuss the photon and graviton excitations in the reduced theory and the ``spectral history'' of the evolution of the quantum Universe from inflation until the classical Friedman stage.

Ocean modeling in a global ocean observing system

The oceanographic community is currently contemplating the design of a global ocean climate observing system to help monitor, describe, and understand the seasonal to decadal climate changes of the ocean and to provide the observations needed for climate prediction. This review attempts to define a role for modeling within that system, the central theme being that the observational and modeling elements must be developed in concert, with the presence of one enhancing the value of the other. Three distinct categories of model‐to‐data interface are identified. In the first class, models and data collection develop separately, being joined only by intermittent validation steps. In the second, and by far most important, class the model and data collection evolve together, either in a time‐space data assimilation and prediction system, or through the application of inverse methods. In the final category, model information feeds back to the observing system design, and vice versa, and the model assimilation system provides quality control on the data. The key role of (atmospheric) models in the determination of surface fluxes to drive ocean models is discussed. A nontrivial role is proposed for ocean models whereby they provide additional, and largely independent, constraints on atmospheric forecast system estimates. The role of ocean models in the analysis of surface and upper ocean fields needs to be developed, particularly with respect to salinity and nonphysical fields. The use of models in rationalizing the choice of observation platforms is discussed, together with some of the difficulties in interpreting such studies. The state of tropical ocean prediction is reviewed with particular emphasis on systems that assimilate subsurface temperature data. A range of thermocline models are also reviewed with the emphasis on subduction and the problem of initializing and constraining models that resolve mesoscale eddies. Some of the issues involved in matching the models to particular observational methods, and vice versa, are discussed with respect to tropical ocean and thermocline modeling. The current state of global ocean and coupled climate general circulation models and models for studying tracer circulation and coupled physical‐biological systems is evaluated. This prognostic path and the products and knowledge derived from integrations are contrasted with the inverse modeling approach which attempts to infer ocean circulation through a combination of observational and modeling constraints. Again we speculate on the model‐data interface and on the different measurement strategies and data requirements. The concept of community modeling and the need for substantial resources and international organization are discussed. A case for global ocean observing system centers with colocated modeling and data collection is made, but with model diversity and individuality emphasized.

Can Poincaré gauge theory be saved?

Recent investigations on the field equations of Poincare gauge theory seem to indicate that the only subclass of theories well founded on a reasonable translation limit are actually ruled out by the lack of a well-defined initial-value problem, and, in particular, by tachyonic torsion solutions. We show, however, that these nonphysical torsion fields may be transformed into mere Lagrange multipliers by symmetries that necessarily come along with any 3+1 decomposition of space-time. We even invert the argument by pointing out that the incriminated theories are the only ones that allow for the nonphysical fields to be trivialized in that way, and the canonical variables to be reduced to a set with a well-defined initial-value problem.

Some aspects of the quantization ofp-forms and reducible gauge theories

The quantization of thep-form inD dimensions is carried out according to both an extension of the BRST formalism and a method due to A. S. Schwarz. The latter yields a suggestive interpretation of the role of nonphysical fields in the quantization of reducible gauge theories. The introduction of gauge conditions of a different type (namely self-dual) modifies the ghost spectrum but does not affect the partition function.

Matrix interpretation of the spectral iteration technique (electromagnetic scattering)

A matrix interpretation of the spectral iteration technique is presented to illustrate improvements in accuracy and convergence for both transverse magnetic and transverse electric waves incident on two-dimensional homogeneous scatterers producing solutions identical to a method of moments scheme. In this scheme, it is possible to improve the convergence rate of the technique by the use of nonphysical Green's function terms in the extended matrix. These terms result in the generation of a nonphysical field outside the scatterer, while still maintaining the correct solution of the current. Although the problem of nonconvergence has not been entirely overcome, a particular taper method used in the examples provided shows an improvement over their nontapered counterparts.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The triangle anomaly in the light-cone gauge

It is shown that the triangle anomaly can be evaluated in the light-cone gauge and that the result obtained is consistent with the usual covariant one. We use two different procedures: (i) Eliminating the nonphysical fields from the covariant anomalous Ward identity. (ii) Carrying out a chiral transformation on the light-cone Lagrangian. The use of both dimensional and Pauli-Villars regularisations are discussed.