The Experts below are selected from a list of 81 Experts worldwide ranked by ideXlab platform
Vladimir S Netchitailo - One of the best experts on this subject based on the ideXlab platform.
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Mathematical Overview of Hypersphere World-Universe Model
Journal of High Energy Physics Gravitation and Cosmology, 2017Co-Authors: Vladimir S NetchitailoAbstract:The Hypersphere World-Universe Model (WUM) provides a mathematical framework that allows calculating the primary cosmological Parameters of the World which are in good agreement with the most recent measurements and observations. WUM explains the experimental data accumulated in the field of Cosmology and Astroparticle Physics over the last decades: the age of the World and critical energy density; the Gravitational Parameter and Hubble’s Parameter; temperatures of the cosmic microwave background radiation and the peak of the far-infrared background radiation; the concentration of intergalactic plasma and time delay of Fast Radio Bursts. Additionally, the model predicts masses of dark matter particles, photons, and neutrinos; proposes new types of particle interactions (Super Weak and Extremely Weak); shows inter-connectivity of primary cosmological Parameters of the World. WUM proposes to introduce a new fundamental Parameter Q in the CODATA internationally recommended values. This paper is the summary of the mathematical results obtained in [1]-[4].
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mathematical overview of hypersphere world universe model
viXra, 2017Co-Authors: Vladimir S NetchitailoAbstract:The Hypersphere World – Universe Model (WUM) provides a mathematical framework that allows calculating the primary cosmological Parameters of the World that are in good agreement with the most recent measurements and observations. WUM explains the experimental data accumulated in the field of Cosmology and Astroparticle Physics over the last decades: the age of the World and critical energy density; the Gravitational Parameter and Hubble’s Parameter; temperatures of the cosmic microwave background radiation and the peak of the far-infrared background radiation; the concentration of intergalactic plasma and time delay of Fast Radio Bursts. Additionally, the Model makes predictions pertaining to masses of dark matter particles, photons, and neutrinos; proposes new types of particle interactions (Super Weak and Extremely Weak); shows inter-connectivity of primary cosmological Parameters of the World. WUM proposes to introduce a new fundamental Parameter Q in the CODATA internationally recommended values.
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world universe model with time varying Gravitational Parameter
viXra, 2014Co-Authors: Vladimir S NetchitailoAbstract:World – Universe Model is based on three primary assumptions: 1) The World is finite and is expanding inside the Universe with speed equal to the electrodynamic constant c. The Universe serves as an unlimited source of energy that continuously enters into the World from the boundary. 2) Medium of the World, consisting of protons, electrons, photons, neutrinos, and dark matter particles, is an active agent in all physical phenomena in the World. 3) Two fundamental Parameters in various rational exponents define all macro and micro features of the World: Fine-Structure Constant α, and dimensionless quantity Q. While α is constant, Q increases with time, and is in fact a measure of the size and the age of the World. The World – Universe Model explains experimental data accumulated in the field of Cosmology over the last decades: the size and age of the World; critical energy density and the Gravitational Parameter; temperature of the cosmic microwave background radiation and cosmological redshift. Additionally, the Model makes predictions pertaining to masses of dark matter particles and neutrinos; proposes new types of particle interactions (Super Weak and Extremely Weak) and recommends introducing a new fundamental Parameter Q in the CODATA internationally recommended values for calculating time dependent Parameters of the World.
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fundamental Parameter q recommended values of the newtonian Parameter of gravitation hubble s Parameter age of the world and temperature of the microwave background radiation
viXra, 2013Co-Authors: Vladimir S NetchitailoAbstract:This paper gives the self-consistent set of Q-dependent, time varying values of the basic Parameters of the World: Fermi Coupling Parameter, Newtonian Parameter of Gravitation, Hubble’s Parameter, Age of the World, and Temperature of the Microwave Background Radiation. It describes in detail the adjustment of the values of the Parameters based on the World – Universe Model. The obtained set of values is recommended for consideration in CODATA Recommended Values of the Fundamental Physical Constants 2014. Keywords: World – Universe Model, Fundamental Parameter Q , Fermi Coupling Parameter, Gravitational Parameter, Hubble’s Parameter, Temperature of Microwave Background Radiation, Size of the World, Age of the World, CODATA.
G. Nath - One of the best experts on this subject based on the ideXlab platform.
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Spherical Shock Generated by a Moving Piston in a Nonideal Gas under Gravitation Field with Monochromatic Radiation and Magnetic Field
Journal of Engineering Physics and Thermophysics, 2020Co-Authors: G. NathAbstract:Similarity solutions for the propagation of a spherical shock wave generated by a moving piston in a nonideal gas under the influence of a Gravitational field and azimuthal magnetic field with monochromatic radiation are obtained. The Gravitational field is due to a central mass at the origin, i.e., the Roche model is valid. The Gravitational effect of the gas itself is neglected in comparison with the attraction of the central mass at the origin. We considered that the radiation flux moves through an electrically conducting nonideal gas with constant intensity and energy is absorbed only behind the shock which moves in the direction opposite to the radiation flux. The results are discussed and compared with ones for a perfect gas, as well as for the cases of the influence of the Gravitational field and of the absence of this field. The effect of the variations of the Alfven–Mach number, Gravitational Parameter, adiabatic exponent, and of the Parameter of gas nonidealness are discussed in details.
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shock wave driven out by a piston in a mixture of a non ideal gas and small solid particles under the influence of the gravitation field with monochromatic radiation
Chinese Journal of Physics, 2018Co-Authors: G. NathAbstract:Abstract Similarity solutions for a spherical shock wave in a mixture of small solid particles of micro size and a non-ideal gas are discussed under the influence of the Gravitational field with monochromatic radiation. The solid particles are uniformly distributed in the mixture, and the shock wave is assumed to be driven by a piston. It is assumed that the equilibrium flow-conditions are maintained and the moving piston continuously supplies the variable energy input. Due to the central mass ( m ¯ ) at the origin (Roche model), the medium is considered to be under the influence of the Gravitational field. In comparison to the attraction of the central mass at the origin, the Gravitational effect of the mixture itself is neglected. The density of the undisturbed medium is assumed to be constant in order to obtain the self-similar solutions. The effect of the Parameter of non-idealness of the gas b ¯ , the mass concentration of solid particles in the mixture μp, the ratio of the density of solid particles to the initial density of the gas Ga and the Gravitational Parameter G0 are obtained. It is shown that due to an increase in the Gravitational Parameter the compressibility of the medium at any point in the flow field behind the shock front decrease and the flow variables velocity, pressure, radiation flux and shock strength are increased. Also, an increase in the ratio of the density of solid particles to the initial density of the gas Ga and the Gravitational Parameter G0 has the same effect on the shock strength and the reverse effect on the compressibility. The non-idealness of the gas causes a decrease in the shock strength and widens the disturbed region between the piston and the shock.
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exact solution for a magnetogasdynamical cylindrical shock wave in a self gravitating rotating perfect gas with radiation heat flux and variable density
Journal of Engineering Physics, 2018Co-Authors: G. Nath, Sumeeta Singh, Pankaj Kumar SrivastavaAbstract:An exact similarity solution for a magnetoradiative cylindrical shock wave in a self-gravitating rotating perfect gas is obtained. The density, azimuthal velocity, and magnetic field strength are assumed to vary in an undisturbed medium. It is shown that the flow variables, namely, the radial velocity, pressure, magnetic field strength, azimuthal velocity, mass, and the radiation flux, decrease from the highest values at the shock front to zero; however, the density tends to infinity as the symmetry axis is approached. The effects of variation in the magnetic field strength, Gravitational Parameter, rotational Parameter, and in the adiabatic exponent on the flow variables and shock strength are discussed. The solutions obtained for self-gravitating and nongravitating media are compared. The total energy of the shock wave is shown to be not constant.
Matthew West - One of the best experts on this subject based on the ideXlab platform.
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geometric interpretation of adjoint equations in optimal low thrust trajectories
AIAA AAS Astrodynamics Specialist Conference and Exhibit, 2008Co-Authors: S Pifko, Alan Zorn, Matthew WestAbstract:Time-optimal control of two seemingly unrelated problems are solved using Pontryagin’s Maximum Principle. The first is a simple double integrator in R in which the state is driven to a desired terminal state in minimum time. The second is an orbiting spacecraft in R which transitions from its current orbit into a desired terminal orbit in minimum time. In both cases, thrust is continuously available but limited in magnitude. The two problems are related by the Gravitational Parameter of the major body orbited. As the Gravitational Parameter is mathematically varied to zero, the orbiting spacecraft takes on the dynamics of a double integrator. A two-point boundary value problem is created when Pontryagin’s Maximum Principle is applied to solve the two problems. Shooting methods are typically used in the solution, but they require reasonably close a priori estimates of the initial or final values of the costate for the shooting method to converge. The adjoint equations of the double integrator have a simple solution. The derived optimal control is shown to be related to the adjoint solution in a simple geometric manner. A method is presented to estimate the initial costate and terminal time for the double integrator problem. The possibility that the initial estimate for the double integrator may provide an initial estimate for the related orbital transfer problem is explored. Numerical examples of the two problems illustrate the method.
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geometric interpretation of adjoint equations in optimal low thrust space flight
AIAA AAS Astrodynamics Specialist Conference and Exhibit, 2008Co-Authors: S Pifko, Alan Zorn, Matthew WestAbstract:Time-optimal control of two seemingly unrelated problems are solved using Pontryagin’s Maximum Principle. The first is a simple double integrator in R 2 in which the state is driven to a desired terminal state in minimum time. The second is an orbiting spacecraft in R 2 which transitions from its current orbit into a desired terminal orbit in minimum time. In both cases, thrust is continuously available but limited in magnitude. The two problems are related by the Gravitational Parameter of the major body orbited. As the Gravitational Parameter is mathematically varied to zero, the orbiting spacecraft takes on the dynamics of a double integrator. A two-point boundary value problem is created when Pontryagin’s Maximum Principle is applied to solve the two problems. Shooting methods are typically used in the solution, but they require reasonably close a priori estimates of the initial or final values of the costate for the shooting method to converge. The adjoint equations of the double integrator have a simple solution. The derived optimal control is shown to be related to the adjoint solution in a simple geometric manner. A method is presented to estimate the initial costate and terminal time for the double integrator problem. The possibility that the initial estimate for the double integrator may provide an initial estimate for the related orbital transfer problem is explored. Numerical examples of the two problems illustrate the method.
Ryan P. Russell - One of the best experts on this subject based on the ideXlab platform.
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IAC-08-C1.2.5 A FAST SECOND-ORDER ALGORITHM FOR PRELIMINARY DESIGN OF LOW-THRUST TRAJECTORIES
2016Co-Authors: Gregory Lantoine, Ryan P. RussellAbstract:Solar system exploration missions require demanding propulsion capabilities. From that point of view, low-thrust technology is increasingly considered since it uses propellant more efficiently. However, the optimization of the resulting trajectories is usually difficult and time consuming. In this paper, we develop a fast algorithm for preliminary design of low-thrust trajectories for spacecraft in a near Keplerian environment. The method achieves order of magnitude speed improvements at the expense of a minor accuracy reduction in the model fidelity. The approach is based on differential dynamic programming, a proven second-order technique that relies on Bellman’s Principle of Optimality and successive minimization of quadratic approximations. Whereas traditional formulations require on expensive numerical integrations to solve the problem, our approach takes advantage of the well-known analytic partial derivatives of Keplerian motion to enable considerable faster computations. Preliminary numerical results are presented and compared to existing algorithms to illustrate the performance and the robustness of our approach. It is shown that our method provides similar results and is fast, easy to use, and enjoys small convergence sensitivities. It is therefore highly valued for preliminary design where large trade spaces have to be assessed rapidly. Nomenclature Φ1 First-order state transition matrix Φ2 Second-order state transition matrix x State vector X Augmented state vector ∆v Velocity impulse vector F Transition function vector p Equality constraint vector h Inequality constraint vector m Mass g0 Reference gravity acceleration value Isp Specific impulse of the engine Tmax Maximum thrust of the engine µ Gravitational Parameter a Semi-major axis ψ Universal variable Sn n th universal function E Universal eccentric anomaly F Universal hyperbolic anomaly f, g Lagrange coefficient
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AAS 13-728 A FAST AND ROBUST MULTIPLE REVOLUTION LAMBERT ALGORITHM USING A COSINE TRANSFORMATION
2016Co-Authors: Nitin Arora, Ryan P. RussellAbstract:A new universal variable is introduced to improve solution performance for the multiple rev-olution Lambert problem. The formulation, motivated by the approach of Bate, Mueller and White, is based on the cosine of the change in eccentric anomaly and uses a new geome-try Parameter to simplify the the universal time of flight equation and the associated partial derivatives. Judicious initial guesses and a second order correction step lead to rapid root-solving and a reduction in the number of minimization calls typically required to bound the multiple revolution case. The proposed method is demonstrated to be statistically as accurate as the Gooding method, while achieving 40-60 % reductions in runtime. NOMENCLATURE x Sundman transformation variable k New universal variable a Semimajor axis e Eccentricity p Semilatus rectum ✓ Transfer angle d Transfer angle Parameter (+1 for 0 < ✓ < ⇡,-1 for ⇡ < ✓ < 2⇡) f, g Lagrange f and g functions ⌧ Lambert geometry Parameter E/F Change in eccentric / hyperbolic anomaly i ith spacecraft revolution M Mass of the body N Number of spacecraft revolutions GM Gravitational Parameter of the primary T ⇤ Target time of flight k ⇤ Value of k corresponding to T⇤ k̃ ⇤ Initial guess for k⇤ k⇤i Value of k corresponding to T ⇤ for the ith revolution transfer k̃⇤i Initial guess for k
S Pifko - One of the best experts on this subject based on the ideXlab platform.
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geometric interpretation of adjoint equations in optimal low thrust trajectories
AIAA AAS Astrodynamics Specialist Conference and Exhibit, 2008Co-Authors: S Pifko, Alan Zorn, Matthew WestAbstract:Time-optimal control of two seemingly unrelated problems are solved using Pontryagin’s Maximum Principle. The first is a simple double integrator in R in which the state is driven to a desired terminal state in minimum time. The second is an orbiting spacecraft in R which transitions from its current orbit into a desired terminal orbit in minimum time. In both cases, thrust is continuously available but limited in magnitude. The two problems are related by the Gravitational Parameter of the major body orbited. As the Gravitational Parameter is mathematically varied to zero, the orbiting spacecraft takes on the dynamics of a double integrator. A two-point boundary value problem is created when Pontryagin’s Maximum Principle is applied to solve the two problems. Shooting methods are typically used in the solution, but they require reasonably close a priori estimates of the initial or final values of the costate for the shooting method to converge. The adjoint equations of the double integrator have a simple solution. The derived optimal control is shown to be related to the adjoint solution in a simple geometric manner. A method is presented to estimate the initial costate and terminal time for the double integrator problem. The possibility that the initial estimate for the double integrator may provide an initial estimate for the related orbital transfer problem is explored. Numerical examples of the two problems illustrate the method.
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geometric interpretation of adjoint equations in optimal low thrust space flight
AIAA AAS Astrodynamics Specialist Conference and Exhibit, 2008Co-Authors: S Pifko, Alan Zorn, Matthew WestAbstract:Time-optimal control of two seemingly unrelated problems are solved using Pontryagin’s Maximum Principle. The first is a simple double integrator in R 2 in which the state is driven to a desired terminal state in minimum time. The second is an orbiting spacecraft in R 2 which transitions from its current orbit into a desired terminal orbit in minimum time. In both cases, thrust is continuously available but limited in magnitude. The two problems are related by the Gravitational Parameter of the major body orbited. As the Gravitational Parameter is mathematically varied to zero, the orbiting spacecraft takes on the dynamics of a double integrator. A two-point boundary value problem is created when Pontryagin’s Maximum Principle is applied to solve the two problems. Shooting methods are typically used in the solution, but they require reasonably close a priori estimates of the initial or final values of the costate for the shooting method to converge. The adjoint equations of the double integrator have a simple solution. The derived optimal control is shown to be related to the adjoint solution in a simple geometric manner. A method is presented to estimate the initial costate and terminal time for the double integrator problem. The possibility that the initial estimate for the double integrator may provide an initial estimate for the related orbital transfer problem is explored. Numerical examples of the two problems illustrate the method.
