Optimal nonlinear filtration of MP streams

The problem is solved of the filtration of a fluctuating Poisson stream of events, the intensity of which is a function of some control process. This is a diffusion Markov random process with known coefficients of drift and diffusion. An equation is obtained determining the law of change of the a posteriori probability density of values of the control process in intervals of time between the appearance of events of the stream and the formulas of recalculation of this probability density at the moments of appearance of the events. The estimate of the intensity of the stream minimizes the mean-square error.Minsk Radiotechnical Institute. V. V. Kuibyshev Tomsk State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 54–60, December, 1993.     

Comparison of the oxidation of two porphyrin complexes by bromate with respect to wave propagation

The kinetics and mechanism of the oxidation of iron(III) protoporphyrin IX (hemin) and iron(III) meso-tetra(4-sulfonatophenyl)porphine (TPPSFe) were compared. Both reactions exhibit sigmoid-shaped time dependence of the absorbance of the porphyrin complexes during the course of the reaction. The oxidation of hemin was proved to be an autocatalytic reaction resembling very much the autocatalytic subset reaction of the BZ oscillators. The oxidation of TPPSFe was proved not to be autocatalytic. It consists of consecutive reaction steps without any feedback. One of the intermediates absorbing in the same region as TPPSFe could be identified as an iron(V)-oxo complex of TPPS. According to the kinetic differences, single autocatalytic wave fronts could be observed in the autocatalytic hemin-bromate reaction if hemin was fixed and stabilized in silica gels, while no wave formation appeared in the TPPSFe-bromate system. The kinetic differences are in agreement with the different structures of the two porphyrin complexes.     

Comparison of two different carbon nanotube-based surfaces with respect to potassium ferricyanide electrochemistry

This paper describes the electrochemical investigation of two multi-walled carbon nanotube-based electrodes using potassium ferricyanide as a benchmark redox system. Carbon nanotubes were fabricated by chemical vapor deposition on silicon wafer with camphor and ferrocene as precursors. Vertically-aligned as well as islands of horizontally-randomly-oriented carbon nanotubes were obtained by varying the growth parameters. Cyclic voltammetry was the employed method for this electrochemical study. Vertical nanotubes showed a slightly higher kinetic. Regarding the sensing parameters we found a sensitivity for vertical nanotubes almost equal to the sensitivity obtained with horizontally/randomly oriented nanotubes (71.5 ± 0.3 μA/(mM cm²) and 62.8 ± 0.3 μA/(mM cm²), respectively). In addition, values of detection limit are of the same order of magnitude. Although tip contribution to electron emission has been shown to be greatly larger than the lateral contribution on single carbon nanotubes per unit area, the new findings reported in this paper demonstrate that the global effects of nanotube surface on potassium ferricyanide electrochemistry are comparable for these two types of nanostructured surfaces.     

A new approach to determining symmetry groups of filtration properties of porous media in nonlinear filtration laws

Theoretical analysis of filtration properties of porous media for orthotropic and monoclinic symmetry groups has been carried out. It is shown how it is possible to establish a type of symmetry with the help of special laboratory investigations and to distinguish groups with orthotropic and monoclinic symmetry. It is established that the criterion for solving this problem is the use of nonlinear Darcy law at high flow velocities, where the effects of asymmetry of filtration properties manifest themselves upon a change in the flow direction.     

On the spontaneous-coherence-transfer-induced sign change of a sub-natural-width nonlinear resonance

A simple theoretical model is proposed which describes the positive sign of the nonlinear absorption resonances in the experiments of Akul’shin et al. [Phys. Rev. A 57, 2996 (1998)]. An analytical expression for the linear response to a weak probe field is obtained in the weak-saturation limit. It is shown that the positive sign of sub-natural-width resonances is due to the spontaneous transfer of low-frequency coherence from an excited level to the ground state. Pis’ma Zh. éksp. Teor. Fiz. 69, No. 11, 776–781 (10 June 1999)     

Comparison of soliton robustness with respect to polarization-mode dispersion with first-order polarization-mode dispersion compensated linear systems

Soliton robustness to polarization-mode dispersion (PMD) is compared, both analytically and numerically, with that of linear pulses that use first-order PMD compensation. It is found that soliton robustness to PMD is comparable with first-order PMD compensation and in some cases is even better. The effects of soliton control methods on soliton robustness to PMD were also investigated, and it was found that soliton control methods can significantly improve the soliton's robustness to PMD, particularly for long-distance systems.     

Comparison of eight unwrapping algorithms applied to Fourier-transform profilometry

Phase unwrapping is a task common to many applications like interferometry imaging, medical magnetic resonance imaging, solid-state physics, etc. Fourier transform profilometry (FTP) values the height distribution of object, elaborating the interference between a plane reference grating and a deformed object grating. Since the height information is extracted from the phase of a complex function, the phase unwrapping is a critical step of the process. Several unwrapping algorithms are proposed in literature, but applied to measurement technologies different from FTP. The purpose of this paper is to define the performances of eight different unwrapping algorithms applied to FTP optical scan method and to define the best one. The algorithms chosen are: Goldstein's algorithm, quality guided path following method, Mask cut method, Flynn's method, multi-grid method, weighted multi-grid method, preconditioned conjugate gradient method and minimum L_p-norm method. The methods were tested on real images acquired by a FTP scanner developed and calibrated for these experiments. The objects used vary from simple geometries, like planes and cylinders, to complex shapes of common use objects. Algorithms were qualified considering the phase unwrapping errors, execution time and accuracy of the shape of objects obtained from the scan method in comparison with real ones. The results show that quality guided algorithm best fits in FTP application.     

Derivatives of the hamiltonian eigenvalues with respect to parameters

Explicit equations are obtained which define the derivatives with respect to parameters entering in the Hamiltonian of the eigenvalues of the Hamiltonian (through third order in the degenerate and nondegenerate cases). A method is indicated of introducing a basis depending on the parameters. A compact expression is obtained for the correction of arbitrary order to the energy in the Rayleigh-Schrodinger perturbation theory.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii Fizika, No. 3, pp. 72–75, March, 1972.     

How to measure the earth's velocity with respect to absolute space

In our absolute space-time theory the time dilation is treated as an absolute phenomenon and it appears as a result of the motion of the material systems with respect to absolute space. Hence, comparing the courses of two atomic clocks put at two antipodal points of the equator (which in the different hours of the day move with different velocities with respect to the absolute space), one can establish the velocity of the Earth as a whole.     

Average coherence with respect to complementary measurements

We investigate the average coherence with respect to a complete set of complementary measurements.By using a Wigner-Yanase skew information-based coherence measure introduced in Luo and Sun(2017 Phys.Rev.A 96,022130),we evaluate the average coherence of a state with respect to any complete set of mutually unbiased measurements and general symmetric informationally complete measurements,respectively.We also establish analytically the relations among these average coherences.     

Scaling with respect to disorder in time-to-failure

We revisit a simple dynamical model of rupture in random media with long-range elasticity to test whether rupture can be seen as a first-order or a critical transition. We find a clear scaling of the macroscopic modulus as a function of time-to-rupture and of the amplitude of the disorder, which allows us to collapse neatly the numerical simulations over more than five decades in time and more than one decade in disorder amplitude onto a single master curve. We thus conclude that, at least in this model, dynamical rupture in systems with long-range elasticity is a genuine critical phenomenon occurring as soon as the disorder is non-vanishing. Received: 11 July 1997 / Revised: 6 November 1997 / Accepted: 10 November 1997     

Comparison of beaked whale detection algorithms

Due to recent advances in passive acoustic monitoring techniques, beaked whales are now more effectively detected acoustically than visually during vessel-based (e.g. line-transect) surveys. Beaked whales signals can be discriminated from those of other cetaceans by the unique characteristics of their echolocation clicks (e.g. duration >175 μs, center frequencies between 30 and 40 kHz, inter-click intervals between 0.2 and 0.4 s and frequency upsweeps). Furthermore, these same characteristics make these signals ideal candidates for testing automated detection and classification algorithms. There are several different beaked whale automated detectors currently available for use. However, no comparative analysis of detectors exists. Therefore, comparison between studies and datasets is difficult. The purpose of this study was to test, validate, and compare algorithms for detection of beaked whales in acoustic line-transect survey data. Six different detection algorithms (XBAT, Ishmael, PAMGUARD, ERMA, GMM and FMCD) were evaluated and compared. Detection trials were run on three sample days of towed-hydrophone array recordings collected by NOAA Southwest Fisheries Science Center (SWFSC) during which were confirmed visual sightings of beaked whales (Ziphius cavirostris and Mesoplodon peruvianus). Detections also were compared to human verified acoustic detections for a subset of these data. In order to measure the probabilities of false detection, each detector was also run on three sample recordings containing clicks from another species: Risso’s dolphin (Grampus griseus). Qualitative and quantitative comparisons and the detection performance of the different algorithms are discussed.     

Reactivity of hydrogen peroxide with respect to ozone

Ozone decomposition in pure water, H₂O₂ aqueous solution, and water with ethanol admixture is investigated. It is found that, in the presence of H₂O₂, ozone decomposes significantly faster than in pure water owing to its interaction with H₂O₂. The effective rate constant (k = (0.023 ± 0.002) l/(mol s)) is determined, which is much higher than the overall rate constant of ozone decomposition in water, but much lower than the specific rate of ozone decomposition in water in the presence of common organic admixtures (fulvic acids, ethanol). It is concluded that at the combined use of O₃ and H₂O₂ for the decomposition of organic admixtures in water, the contribution of their interaction with each other is little.     

Differentiating the shape of stellarator coils with respect to the plasma boundary

The task of designing the geometry of a set of current-carrying coils that produce the magnetic field required to confine a given plasma equilibrium in stellarators is expressed as a minimization principle, namely that the coils minimize a suitably defined error expressed as a surface integral, which is recognized as the quadratic-flux. A penalty on the coil length is included to avoid pathological solutions. A simple expression for how the quadratic-flux and coil length vary as the coil geometry varies is derived, and an expression describing how this varies with variations in the surface geometry is derived. These expressions allow efficient coil-design algorithms to be implemented, and also enable efficient algorithms for varying the shape of the plasma surface in order to simplify the coil geometry, and a numerical illustration of this is given.