Solar Radiation Pressure Research Papers (original) (raw)
The solidification behavior of liquid metal in a container under rapid cooling process is one of the major concerns to be analyzed. In order to analyze its fundamental behavior, a three- dimensional (3D) fluid dynamics simulation was... more
The solidification behavior of liquid metal in a container under rapid cooling process is one of the major concerns to be analyzed. In order to analyze its fundamental behavior, a three- dimensional (3D) fluid dynamics simulation was developed using a particle-based method, known as the smoothed particle hydrodynamics (SPH) method. Governing equations that determine the fluid motion and heat transfer involving phase change process are solved by discretizing their gradient and Laplacian term with the moving particles and calculating the interaction with its neighboring particles. The results demonstrate that the SPH mehod can successfully reproduce the behavior and defect prediction of liquid metal solidification process.
As a step toward absolute calibration of optical tweezers, a first-principles theory of trapping forces with no adjustable parameters, corrected for spherical aberration, is experimentally tested. Employing two very different setups, we... more
As a step toward absolute calibration of optical tweezers, a first-principles theory of trapping forces with no adjustable parameters, corrected for spherical aberration, is experimentally tested. Employing two very different setups, we find generally very good agreement for the transverse trap stiffness as a function of microsphere radius for a broad range of radii, including the values employed in practice, and at different sample chamber depths. The domain of validity of the WKB (``geometrical optics'') approximation to the theory is verified. Theoretical predictions for the trapping threshold, peak position, depth variation, multiple equilibria, and ``jump'' effects are also confirmed.
The standard accretion discs are known to be thermally and viscously unstable over a certain range of temperatures. In the inner disc regions there may develop radiation pressure driven instability, which is possibly related to the rapid... more
The standard accretion discs are known to be thermally and viscously unstable over a certain range of temperatures. In the inner disc regions there may develop radiation pressure driven instability, which is possibly related to the rapid variability detected in AGNs in the UV range. In the outer disc develops the ionization instability, similar to that in the cataclysmic variables,
We review recent progress in the field of optomechanics, where one studies the effects of radiation on mechanical motion. The paradigmatic example is an optical cavity with a movable mirror, where the radiation pressure can induce... more
We review recent progress in the field of optomechanics, where one studies the effects of radiation on mechanical motion. The paradigmatic example is an optical cavity with a movable mirror, where the radiation pressure can induce cooling, amplification and nonlinear dynamics of the mirror.
The combined cycle gas turbine integrates the Brayton cycle as topping cycle and the steam turbine Rankine cycle as bottoming cycle in order to achieve higher thermal efficiency and proper utilization of energy by minimizing the energy... more
The combined cycle gas turbine integrates the Brayton cycle as topping cycle and the steam turbine Rankine cycle as bottoming cycle in order to achieve higher thermal efficiency and proper utilization of energy by minimizing the energy loss to a minimum. In this work, the effect of various operating parameters such as maximum temperature and pressure of Rankine cycle, turbine inlet temperature and pressure ratio of Brayton cycle on the net output work and thermal efficiency of the combine cycle are investigated. The outcome of this work can be utilized in order to facilitate the design of a combined cycle with higher efficiency and output work. A MATLAB simulation has been carried out to study the effects and influences of the above mentioned parameters on the efficiency and work output.
The Doppler effect is one of the dominant broadening mechanisms in thermal vapor spectroscopy. For two-photon transitions one would naively expect the Doppler effect to cause a residual broadening, proportional to the wave-vector... more
The Doppler effect is one of the dominant broadening mechanisms in thermal vapor spectroscopy. For two-photon transitions one would naively expect the Doppler effect to cause a residual broadening, proportional to the wave-vector difference. In coherent population trapping (CPT), which is a narrow-band phenomenon, such broadening was not observed experimentally. This has been commonly attributed to frequent velocity-changing collisions, known to narrow Doppler-broadened one-photon absorption lines (Dicke narrowing). Here we show theoretically that such a narrowing mechanism indeed exists for CPT resonances. The narrowing factor is the ratio between the atom's mean free path and the wavelength associated with the wave-vector difference of the two radiation fields. A possible experiment to verify the theory is suggested.
We present a new and more accurate expression for the radiation pressure and Poynting-Robertson drag forces; it is more complete than previous ones, which considered only perfectly absorbing particles or artificial scattering laws. Using... more
We present a new and more accurate expression for the radiation pressure and Poynting-Robertson drag forces; it is more complete than previous ones, which considered only perfectly absorbing particles or artificial scattering laws. Using a simple heuristic derivation, the equation of motion for a particle of mass m and geometrical cross section A, moving with velocity v through a radiation field of energy flux density S, is found to be (to terms of order )
This book chapter reports on theoretical protocols for generating nonclassical states of light and mechanics. Nonclassical states are understood as squeezed states, entangled states or states with negative Wigner function, and the... more
This book chapter reports on theoretical protocols for generating nonclassical states of light and mechanics. Nonclassical states are understood as squeezed states, entangled states or states with negative Wigner function, and the nonclassicality can refer either to light, to mechanics, or to both, light and mechanics. In all protocols nonclassicallity arises from a strong optomechanical coupling. Some protocols rely in addition on homodyne detection or photon counting of light.
In this paper, we applied an improved Smoothing Particle Hydrodynamics (SPH) method by using gradient kernel renormalization in three-dimensional cases. The purpose of gradient kernel renormalization is to improve the accuracy of... more
In this paper, we applied an improved Smoothing Particle Hydrodynamics (SPH) method by using gradient kernel renormalization in three-dimensional cases. The purpose of gradient kernel renormalization is to improve the accuracy of numerical simulation by improving gradient kernel approximation. This method is implemented for simulating free surface flows, in particular dam break case with rigid ball structures and the propagation of waves towards a slope in a rectangular tank.
On the basis of the Lunar Laser Ranging Data released by NASA on the Silver Jubilee Celebration of Man Landing on Moon on 21st July 1969-1994, theoretical formulation of Earth-Moon tidal interaction was carried out and Planetary Satellite... more
On the basis of the Lunar Laser Ranging Data released by NASA on the Silver Jubilee Celebration of Man Landing on Moon on 21st July 1969-1994, theoretical formulation of Earth-Moon tidal interaction was carried out and Planetary Satellite Dynamics was established. It was found that this mathematical analysis could as well be applied to Star and Planets system and since every star could potentially contain an extra-solar system, hence we have a large ensemble of exoplanets to test our new perspective on the birth and evolution of solar systems. Till date 403 exoplanets have been discovered in 390 extra-solar systems. I have taken 12 single planet systems, 4 Brown Dwarf - Star systems and 2 Brown Dwarf pairs. Following architectural design rules are corroborated through this study of exoplanets. All planets are born at inner Clarke Orbit what we refer to as inner geo-synchronous orbit in case of Earth-Moon System. By any perturbative force such as cosmic particles or radiation pressure, the planet gets tipped long of aG1 or short of aG1. Here aG1 is inner Clarke Orbit. The exoplanet can either be launched on death spiral as CLOSE HOT JUPITERS or can be launched on an expanding spiral path as the planets in our Solar System are. It was also found that if the exo-planet are significant fraction of the host star then those exo-planets rapidly migrate from aG1 to aG2 and have very short Time Constant of Evolution as Brown Dwarfs have. This vindicates our basic premise that planets are always born at inner Clarke Orbit. This study vindicates the design rules which had been postulated at 35th COSPAR Scientific Assembly in 2004 at Paris, France, under the title ,New Perspective on the Birth & Evolution of Solar Systems.
In 1904 Austrian physicist Fritz Hasenohrl (1874-1915) examined blackbody radiation in a reflecting cavity. By calculating the work necessary to keep the cavity moving at a constant velocity against the radiation pressure he concluded... more
In 1904 Austrian physicist Fritz Hasenohrl (1874-1915) examined blackbody radiation in a reflecting cavity. By calculating the work necessary to keep the cavity moving at a constant velocity against the radiation pressure he concluded that to a moving observer the energy of the radiation would appear to increase by an amount E=(3/8)mc^2, which in early 1905 he corrected to E=(3/4)mc^2. Because relativistic corrections come in at order v^2/c^2 and Hasenohrl's gedankenexperiment evidently required calculations only to order v/c, it is initially puzzling why he did not achieve the answer universally accepted today. Moreover, that mmm should be equal to (4/3)E/c^2 has led commentators to believe that this problem is identical to the famous "4/3 problem" of the self-energy of the electron and they have invariably attributed Hasenohrl's mistake to neglect of the cavity stresses. We examine Hasenohrl's papers from a modern, relativistic point of view in an attempt to understand where exactly he went wrong. The problem turns out to be a rich and challenging one with strong resonances to matters that remain controversial. We give an acceptable relativistic solution to the conundrum and show that virtually everything ever written about Hasenohrl's thought experiment, including a 1923 paper by Enrico Fermi, is misleading if not incorrect.
We report on a bistable light transmission through a planar metamaterial consisted of a metal pattern of weakly asymmetric elements placed on a nonlinear substrate which enables sharp resonance response by excitation of a trapped mode. A... more
We report on a bistable light transmission through a planar metamaterial consisted of a metal pattern of weakly asymmetric elements placed on a nonlinear substrate which enables sharp resonance response by excitation of a trapped mode. A feedback required for bistability is provided by the coupling between strong trapped mode resonance antiphased currents exited on the metal elements and an intensity of inner field in the nonlinear substrate.
In this paper we have examined the linear stability of triangular equilibrium points in the generalised photogravitational restricted three body problem with Poynting-Robertson drag. We have found the position of triangular equilibrium... more
In this paper we have examined the linear stability of triangular equilibrium points in the generalised photogravitational restricted three body problem with Poynting-Robertson drag. We have found the position of triangular equilibrium points of our problem. The problem is generalised in the sense that smaller primary is supposed to be an oblate spheroid. The bigger primary is considered as radiating. The equations of motion are affected by radiation pressure force, oblateness and P-R drag. All classical results involving photogravitational and oblateness in restricted three body problem may be verified from this result. With the help of characteristic equation, we discussed the stability. Finally we conclude that triangular equilibrium points are unstable.
We present arguments in favor of the proposition that the momentum of light inside a transparent dielectric medium is the arithmetic average of the Minkowski and Abraham momenta. Using the Lorentz transformation of the fields (and of the... more
We present arguments in favor of the proposition that the momentum of light inside a transparent dielectric medium is the arithmetic average of the Minkowski and Abraham momenta. Using the Lorentz transformation of the fields (and of the coordinates) from a stationary to a moving reference frame, we show the consistent transformation of electromagnetic energy and momentum between the two frames. We also examine the momentum of static (i.e., time-independent) electromagnetic fields, and show that the close connection that exists between the Poynting vector and the momentum density extends all the way across the frequency spectrum to this zero-frequency limit. In the specific example presented in this paper, the static field inside a non-absorbing dielectric material turns out to have the Minkowski momentum.
The bright ultraluminous X-ray source (ULX), M33 X-8, has been observed several times by XMM-Newton, providing us with a rare opportunity to 'flux bin' the spectral data and search for changes in the average X-ray spectrum with flux... more
The bright ultraluminous X-ray source (ULX), M33 X-8, has been observed several times by XMM-Newton, providing us with a rare opportunity to 'flux bin' the spectral data and search for changes in the average X-ray spectrum with flux level. The aggregated X-ray spectra appear unlike standard sub-Eddington accretion state spectra which, alongside the lack of discernible variability at any energy, argues strongly against conventional two-component, sub-Eddington models. Although the lack of variability could be consistent with disc-dominated spectra, sub-Eddington disc models are not sufficiently broad to explain the observed spectra. Fits with a ˜ Eddington accretion rate slim disc model are acceptable, but the fits show that the temperature decreases with flux, contrary to expectations, and this is accompanied by the appearance of a harder tail to the spectrum. Applying a suitable two-component model reveals that the disc becomes cooler and less advection dominated as the X-ray flux increases, and this is allied to the emergence of an optically thick Comptonization medium. We present a scenario in which this is explained by the onset of a radiatively driven wind from the innermost regions of the accretion disc, as M33 X-8 exceeds the Eddington limit. Furthermore, we argue that the direct evolution of this spectrum with increasing luminosity (and hence radiation pressure) leads naturally to the two-component spectra seen in more luminous ULXs.
Cavity-enhanced radiation-pressure coupling of optical and mechanical degrees of freedom gives rise to a range of optomechanical phenomena, in particular providing a route to the quantum regime of mesoscopic mechanical oscillators. A... more
Cavity-enhanced radiation-pressure coupling of optical and mechanical degrees of freedom gives rise to a range of optomechanical phenomena, in particular providing a route to the quantum regime of mesoscopic mechanical oscillators. A prime challenge in cavity optomechanics has however been to realize systems which simultaneously maximize optical finesse and mechanical quality. Here we demonstrate for the first time independent control
Optical tweezers and AFM cantilevers are often calibrated by fitting their experimental powerspectra of Brownian motion. We demonstrate here that if this is done with typical weighted least-squares methods the result is a bias of relative... more
Optical tweezers and AFM cantilevers are often calibrated by fitting their experimental powerspectra of Brownian motion. We demonstrate here that if this is done with typical weighted least-squares methods the result is a bias of relative size between -2/n and +1/n on the value of the fitted diffusion coefficient. Here n is the number of power-spectra averaged over, so typical calibrations contain 10-20% bias. Both the sign and the size of the bias depends on the weighting scheme applied. Hence, so do length-scale calibrations based on the diffusion coefficient. The fitted value for the characteristic frequency is not affected by this bias. For the AFM then, force measurements are not affected provided an independent length-scale calibration is available. For optical-tweezers there is no such luck, since the spring constant is found as the ratio of the characteristic frequency and the diffusion coefficient. We give analytical results for the weight-dependent bias for the wide class of systems whose dynamics is described by a linear (integro-)differential equation with additive noise, white or colored. Examples are optical tweezers with hydrodynamic self-interaction and aliasing, calibration of Ornstein-Uhlenbeck models in finance, models for cell-migration in biology, etc. Because the bias takes the form of a simple multiplicative factor on the fitted amplitude (e.g. the diffusion coefficient) it is straightforward to remove, and the user will need minimal modifications to his or her favorite least-square fitting programs. Results are demonstrated and illustrated using synthetic data, so we can compare fits with known true values. We also fit some commonly occurring power spectra once-and-for-all in the sense that we give their parameter values and associated error-bars as explicit functions of experimental power-spectral values.
The equilibrium points and their linear stability has been discussed in the generalized photogravitational Chermnykh's problem. The bigger primary is being considered as a source of radiation and small primary as an oblate spheroid. The... more
The equilibrium points and their linear stability has been discussed in the generalized photogravitational Chermnykh's problem. The bigger primary is being considered as a source of radiation and small primary as an oblate spheroid. The effect of radiation pressure has been discussed numerically. The collinear points are linearly unstable and triangular points are stable in the sense of Lyapunov stability provided mu<muRouth=0.0385201\mu< \mu_{Routh}=0.0385201mu<muRouth=0.0385201. The effect of gravitational potential from the belt is also examined. The mathematical properties of this system are different from the classical restricted three body problem.
Laser trapping is based on the radiation pressure on a small particle in the focal region of a high numerical-aperture objective. Currently, the focal spot of a trapping beam is elongated along the longitudinal direction and thus the... more
Laser trapping is based on the radiation pressure on a small particle in the focal region of a high numerical-aperture objective. Currently, the focal spot of a trapping beam is elongated along the longitudinal direction and thus the axial size of the trapping volume is approximately three times larger than that in the transverse direction. We report on a laser trapping technique under focused evanescent wave illumination. Therefore laser trapping of micro/nano-objects can be achieved in the near-field region with an axial trapping size of approximately 60 nm, which is reduced by approximately one order of magnitude. Hence, this technique is of significant importance in nanometry including single molecule detection and manipulation.