Papers by Ondrej Prof.Assoc. RNDr. Hudak, DrSc.
Structure and properties of samarium hexaboride thin films
Izvestiya Akademii Nauk SSSR, Neorganicheskie Materialy, 1990
Quantum Critical Phenomena and Hubbard Model in 1d with Boundary Fields and Hoppings
An investor is estimating net present value of a firm project and performs risk analysis. Usually... more An investor is estimating net present value of a firm project and performs risk analysis. Usually it is created portfolio hierarchies and make comparison of variants of project based on these hierarchies. Then one finds that portfolio which corresponds to the particular needs of individual groups within the firm. We have formulated a new type of NPV analysis based on the fact that normal distribution of NPV is observed for some projects in some industries. The expected risk of the project is given by variance, in which there is σ n the standard deviation of the year n cash flow, σ I the standard deviation of the investment I in the time zero, ρ I,n the correlation coefficient of the year n cash flow deviation from the average and of the investment I at time zero deviation from the mean investment at time zero, ρ n,n the correlation coefficient of the year n cash flow deviation from the average and of the year n cash flow deviation from the average. The aim function of the investor into the project was found. The investor is characterized by the constant A. The larger constant A the larger preference is given to the project NPV and the larger acceptable risk of the project, and vice versa. We have found that there are contributions in which we have the aim-function-like contribution to the aim function, which is discounted and in which the risk of the n-th year risk is discounted in the second order. Further there is aim-function-like contribution to the aim-function which comes from the initial investment I and its risk σ 2 I .
We study social behaviour of agents on capital markets when these are perturbed by small perturba... more We study social behaviour of agents on capital markets when these are perturbed by small perturbations. We use the mean field method. Social behaviour of agents on capital markets is described: volatility of the market, aversion constant and equilibrium states are discussed. Relaxation behaviour of agents on the capital market is studied. Equation of motion for the agent average number is of the relaxation type. Development of the group of agents in the states corresponding to minimum of the aim function is either linear either exponentially damped. There exist characteristic volatility constants V c3 and V c3 . The constant b of verification of information contribution to the aversion constant A and the A 0 constant of aversion are distinguishing three types of dependencies of the minimum of the aim function on the expected volatility EV and on the expected returns E. Arbitrage trades and group forces lead the group into the equilibrium state. Verification of information intensity influences return back to the equilibrium state. The linear in time damping to the equilibrium state is characterized with the characteristic time T 3 and T 6 , the exponential with a characteristic time τ . Their dependence on the expected volatility, on the expected profit and characteristics of agents is discussed.
On Static Dielectric Response of Microcomposites of the Type Ferrolastics-Dielectrics For Application in Solid Oxide Fuel Cells (SOFC) (arXiv: 1610.09617)
Recently the ground state and some excited states of the half-filled case of the 1d Hubbard model... more Recently the ground state and some excited states of the half-filled case of the 1d Hubbard model were discussed for an open chain with L sites. Authors considered the case when the boundary site has a negative chemical potential-p and the Hubbard coupling U is positive. They have shown by an analytic method that when p is larger than the transfer integral some of the ground-state solutions of the Bethe ansatz equations become complex-valued. They have found that there is a surface phase transition at some critical value pc; when p < pc all the charge excitations have the gap for this case, while there exists a massless charge mode when p> pc. To find whether this ”surface phase transition” is of the first order or of the second order we have used the entanglement entropy concept. The entropy and its derivative has a discontinuity there, so this transition is of the first order. 2 1
N ov 2 00 5 On Static Dielectric Response of Microcomposites of the Type : Ferrolastics-Dielectrics
We describe the static dielectric response of ferroelastic-dielectric microcomposites. Its depend... more We describe the static dielectric response of ferroelastic-dielectric microcomposites. Its dependence on temperature, pressure and concentration is considered for smaller concentrations and for temperatures above the critical temperature. We have found a qualitative agreement with existing experimental data for Al2(WO4)3.
Influence of external electric field on incommensurate-commensurate phase transition in K2SeO4and (NH4)2BeF4crystals. I. Static properties
Journal of Physics C: Solid State Physics, 1983
The author presents a study of the influence of an external electric field on the incommensurate-... more The author presents a study of the influence of an external electric field on the incommensurate-commensurate phase transition in K2SeO4- and (NH4)2BeF4-like crystals. Within the constant-amplitude approximation the same type of thermodynamic potential is found in both cases. The phase diagram in the E-T phase plane is found and should exhibit a Lifshitz point. The susceptibility of the incommensurate phase
Eprint Arxiv Physics 0509102, 2005
An investor is estimating net present value of a firm project and performs risk analysis. Usually... more An investor is estimating net present value of a firm project and performs risk analysis. Usually it is created portfolio hierarchies and make comparison of variants of project based on these hierarchies. Then one finds that portfolio which corresponds to the particular needs of individual groups within the firm. We have formulated a new type of NPV analysis based on the fact that normal distribution of NPV is observed for some projects in some industries. The expected risk of the project is given by variance, in which there is σ n the standard deviation of the year n cash flow, σ I the standard deviation of the investment I in the time zero, ρ I,n the correlation coefficient of the year n cash flow deviation from the average and of the investment I at time zero deviation from the mean investment at time zero, ρ n,n the correlation coefficient of the year n cash flow deviation from the average and of the year n cash flow deviation from the average. The aim function of the investor into the project was found. The investor is characterized by the constant A. The larger constant A the larger preference is given to the project NPV and the larger acceptable risk of the project, and vice versa. We have found that there are contributions in which we have the aim-function-like contribution to the aim function, which is discounted and in which the risk of the n-th year risk is discounted in the second order. Further there is aim-function-like contribution to the aim-function which comes from the initial investment I and its risk σ 2 I .
Eprint Arxiv Physics 0509102, 2005
An investor is estimating net present value of a firm project and performs risk analysis. Usually... more An investor is estimating net present value of a firm project and performs risk analysis. Usually it is created portfolio hierarchies and make comparison of variants of project based on these hierarchies. Then one finds that portfolio which corresponds to the particular needs of individual groups within the firm. We have formulated a new type of NPV analysis based on the fact that normal distribution of NPV is observed for some projects in some industries. The expected risk of the project is given by variance, in which there is σ n the standard deviation of the year n cash flow, σ I the standard deviation of the investment I in the time zero, ρ I,n the correlation coefficient of the year n cash flow deviation from the average and of the investment I at time zero deviation from the mean investment at time zero, ρ n,n the correlation coefficient of the year n cash flow deviation from the average and of the year n cash flow deviation from the average. The aim function of the investor into the project was found. The investor is characterized by the constant A. The larger constant A the larger preference is given to the project NPV and the larger acceptable risk of the project, and vice versa. We have found that there are contributions in which we have the aim-function-like contribution to the aim function, which is discounted and in which the risk of the n-th year risk is discounted in the second order. Further there is aim-function-like contribution to the aim-function which comes from the initial investment I and its risk σ 2 I .
Point-contact properties of YBaâCuâO/sub 7-. delta. / and SmBaâCuâO/sub 7-. delta
The I-V characteristics and their derivatives on the point-heterocontacts of Y(Sm)BaâCuâO/sub 7-Î... more The I-V characteristics and their derivatives on the point-heterocontacts of Y(Sm)BaâCuâO/sub 7-δ/-Cu(Ag) are presented. Three types of dependences were observed. The observed deviations from classical tunneling behavior are explained. The photon energies were determined from the classical PC tunneling spectra.
Point-contact properties of YBa/sub 2/Cu/sub 3/O/sub 7-. delta./and SmBa/sub 2/Cu/sub 3/O/sub 7-. delta
ABSTRACT The I-V characteristics and their derivatives on the point-heterocontacts of Y(Sm)Ba/sub... more ABSTRACT The I-V characteristics and their derivatives on the point-heterocontacts of Y(Sm)Ba/sub 2/Cu/sub 3/O/sub 7-{delta}/-Cu(Ag) are presented. Three types of dependences were observed. The observed deviations from classical tunneling behavior are explained. The photon energies were determined from the classical PC tunneling spectra.
Physics Letters A, 2009
Recently the ground state and some excited states of the half-filled case of the 1d Hubbard model... more Recently the ground state and some excited states of the half-filled case of the 1d Hubbard model were discussed for an open chain with L sites. Authors considered the case when the boundary site has a negative chemical potential -p and the Hubbard coupling U is positive. They have shown by an analytic method that when p is larger than the transfer integral some of the ground-state solutions of the Bethe ansatz equations become complex-valued. They have found that there is a surface phase transition at some critical value p c ; when p < p c all the charge excitations have the gap for this case, while there exists a massless charge mode when p > p c . To find whether this "surface phase transition" is of the first order or of the second order we have used the entanglement entropy concept. The entropy and its derivative has a discontinuity there, so this transition is of the first order.
Monoclinic phase in PZT: order parameter and phase transition from Tetragonal Phase
Phase Transitions, 2008
A solution of the Lagrange–Euler equations for the order parameter–the electric polarisation vect... more A solution of the Lagrange–Euler equations for the order parameter–the electric polarisation vector P–which describes the monoclinic phase in PZT is found exactly in this article for the Gibbs free energy expansion done for the cubic phase up to the sixth–order in the order parameter. The phase transition from the tetragonal phase to the monoclinic phase in materials of the PZT type may be described within the Landau theory of phase transitions used by Haun and co-workers. The phase transition is found to be of the first order in general. The order parameter in the parameter space is two dimensional: the amplitude A and the angle. The PZT material has values of expansion coefficients in the Gibbs free energy such that the exact solution for description of the monoclinic phase is a metastable state. We may conclude then that the monoclinic phase exists in PZT due to higher than sixth-order terms in the Gibbs free energy expansion which are present due to high anharmonicity present in this material.
Dielectric properties of microcomposite ferroelectrics
Phase Transitions, 1999
The dielectric response in two-phase composites of ferroelectric and dielectric materials was stu... more The dielectric response in two-phase composites of ferroelectric and dielectric materials was studied within the quasistatic approximation. Using different effective medium theories (Maxwell-Garnet theory, the effective medium approximation and the Bergman representation) the dielectric function was represented as a distribution of polar modes. One of the main results concerns the existence of modes due to geometric resonances which among other
Static susceptibility in a paraelectric particle
Phase Transitions, 2010
Static dielectric susceptibility for the paraelectric phase of a particle was calculated exactly.... more Static dielectric susceptibility for the paraelectric phase of a particle was calculated exactly. Temperature and diameter dependence are described analytically. There are two regimes of the susceptibility: for temperatures above the bulk critical ferroelectric temperature of the particle and below it. The critical transition temperature from the exact calculation is the same as that from the soft mode approach.
Multirelaxation response of modulated phases in structural order-disorder systems
Journal of Physics: Condensed Matter, 1995
ABSTRACT
The shear stiffness in the incommensurate phase of A2BX4-type crystals
Ferroelectrics, 1983
Analytic formula for the shear stiffness c55 of A2BX4-type crystals is derived in the domain-like... more Analytic formula for the shear stiffness c55 of A2BX4-type crystals is derived in the domain-like regime near the phase transition temperature Tc from the incommensurate into commensurate ferroelectric phase. The anomalous part of c55 is shown to be proportional to the domain wall density. A comparison with the dielectric susceptibility χ3 is made. Theoretical and experimental temperature dependences of c55 in K3SeO4 are discussed.
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Papers by Ondrej Prof.Assoc. RNDr. Hudak, DrSc.