558 research outputs found
Aspidistra nikitensis (Asparagaceae, Nolinoideae), a new species from Vietnam
No full textKalyuzhny, Sergey S., Vislobokov, Nikolay A., Luu, Hong Truong, Plugatar, Yury V., Kuznetsov, Andrey N., Kuznetsova, Svetlana P., Korzhenevsky, Vladislav V., Vin'Kovskaya, Oksana P. (2022): Aspidistra nikitensis (Asparagaceae, Nolinoideae), a new species from Vietnam. Phytotaxa 574 (4): 289-294, DOI: 10.11646/phytotaxa.574.4.4, URL: http://dx.doi.org/10.11646/phytotaxa.574.4.
Tupistra khangii (Asparagaceae), a new species from northern Vietnam
No full textVislobokov, Nikolay A., Тanaka, Noriyuki, Averyanov, Leonid V., Nguyen, Hiep Tien, Nuraliev, Maxim S., Kuznetsov, Andrey N. (2014): Tupistra khangii (Asparagaceae), a new species from northern Vietnam. Phytotaxa 175 (5): 287-292, DOI: 10.11646/phytotaxa.175.5.8, URL: http://dx.doi.org/10.11646/phytotaxa.175.5.
FIGURE 1. Aspidistra nikitensis. A. Flower, front view. B. Flower with partly removed perigone, side view. C, D in Aspidistra nikitensis (Asparagaceae, Nolinoideae), a new species from Vietnam
No full textFIGURE 1. Aspidistra nikitensis. A. Flower, front view. B. Flower with partly removed perigone, side view. C, D. Longitudinal sections of flower. E. Plant with flowers. F, G. Habit.Published as part of Kalyuzhny, Sergey S., Vislobokov, Nikolay A., Luu, Hong Truong, Plugatar, Yury V., Kuznetsov, Andrey N., Kuznetsova, Svetlana P., Korzhenevsky, Vladislav V. & Vin'Kovskaya, Oksana P., 2022, Aspidistra nikitensis (Asparagaceae, Nolinoideae), a new species from Vietnam, pp. 289-294 in Phytotaxa 574 (4) on page 291, DOI: 10.11646/phytotaxa.574.4.4, http://zenodo.org/record/738909
Numerical analysis of dynamical systems : unstable periodic orbits, hidden transient chaotic sets, hidden attractors, and finite-time Lyapunov dimension
No full textIn this article, on the example of the known low-order dynamical models, namely Lorenz, Rössler and Vallis systems, the difficulties of reliable numerical analysis of chaotic dynamical systems are discussed. For the Lorenz system, the problems of existence of hidden chaotic attractors and hidden transient chaotic sets and their numerical investigation are considered. The problems of the numerical characterization of a chaotic attractor by calculating finite-time time Lyapunov exponents and finite-time Lyapunov dimension along one trajectory are demonstrated using the example of computing unstable periodic orbits in the Rössler system. Using the example of the Vallis system describing the El Ninõ-Southern Oscillation it is demonstrated an analytical approach for localization of self-excited and hidden attractors, which allows to obtain the exact formulas or estimates of their Lyapunov dimensions.peerReviewe
FIGURE 2 in Aspidistra xuansonensis (Asparagaceae), a new species from northern Vietnam
No full textFIGURE 2. Flowers of Aspidistra xuansonensis. a. flower with four tepals and bilocular ovary; b. flower with five tepals and bilocular ovary; c. flower with six tepals and bilocular ovary; d, e. flower with six tepals and trilocular ovary with low (d) and high (e) rate of stigma bifurcation; f. flower with seven tepals and quadrilocular ovary; g, h. groups of three (g) to seven flower buds on rhizome (h). As suggested by Vislobokov et al. (2014), flowers are dimerous pentacyclic in (a), 2,5-merous pentacyclic in (b), trimerous in (d-e) and 3.5-merous in (f).Published as part of Vislobokov, Nikolay A., Sokoloff, Dmitry D., Degtjareva, Galina V., Valiejo- Roman, Carmen M. & Kuznetsov, Andrey N., 2014, Aspidistra xuansonensis (Asparagaceae), a new species from northern Vietnam, pp. 226-234 in Phytotaxa 173 (3) on page 229, DOI: 10.11646/phytotaxa.173.3.5, http://zenodo.org/record/515175
FIGURE 1. Tupistra khangii. A. Flowering and fruiting plant. B. Inflorescence. C. Fruits. D in Tupistra khangii (Asparagaceae), a new species from northern Vietnam
No full textFIGURE 1. Tupistra khangii. A. Flowering and fruiting plant. B. Inflorescence. C. Fruits. D. Young portion of inflorescence with flower buds and floral bracts. E. Flower bud and floral bract, side and frontal views. F. Flower, upper and frontal views. G. adaxial aspect of perigone, cut and flattened. H. Flower, sagittal section. Pistil, side view and sagittal section, and frontal and rear views of stigma at early anthesis (I), at mid anthesis (J), and at late anthesis with transversal section of style (K). L. Transversal section of ovary. [All drawn by L. Averyanov and T. Maisak from the type – L. Averyanov et al., CPC 7158].Published as part of Vislobokov, Nikolay A., Тanaka, Noriyuki, Averyanov, Leonid V., Nguyen, Hiep Tien, Nuraliev, Maxim S. & Kuznetsov, Andrey N., 2014, Tupistra khangii (Asparagaceae), a new species from northern Vietnam, pp. 287-292 in Phytotaxa 175 (5) on page 289, DOI: 10.11646/phytotaxa.175.5.8, http://zenodo.org/record/514398
FIGURE 1 in Aspidistra paucitepala (Asparagaceae), a new species with occurrence of the lowest tepal number in flowers of Asparagales
No full textFIGURE 1. Flowers of A. paucitepala. a–c. longitudinal sections of flowers (a, c) and flower bud (b); d. flower with three tepals and supposedly three stamens (side view); e. flower with two tepals and two stamens (cross section at the level of anthers, above the stigma, scanning electron microscopy); f. flower with three tepals and three stamens (top view); g. flower with four tepals and four stamens (top view); h. flowers with four and three tepals occurring on the same individual plant.Published as part of Vislobokov, Nikolay A., Sokoloff, Dmitry D., Degtjareva, Galina V., Valiejo-Roman, Carmen M., Kuznetsov, Andrey N. & Nuraliev, Maxim S., 2014, Aspidistra paucitepala (Asparagaceae), a new species with occurrence of the lowest tepal number in flowers of Asparagales, pp. 270-282 in Phytotaxa 161 (4) on page 273, DOI: 10.11646/phytotaxa.161.4.2, http://zenodo.org/record/513187
FIGURE 2. Tupistra khangii. A in Tupistra khangii (Asparagaceae), a new species from northern Vietnam
No full textFIGURE 2. Tupistra khangii. A. Flowering plant in locus classicus (type specimen CPC 7158). B. Flowering plant in natural habitat (CPC 857). C. Portion of inflorescence at early anthesis (CPC 857). D. Portion of inflorescence at late anthesis (CPC 6344). E. Portion of infructescence with ripening fruits (CPC 6344). F. Flowers at early anthesis (CPC 857). G. Flowers at mid anthesis (CPC 7158). H. Flowers at late anthesis (CPC 6344). I. Style and stigma at mid anthesis (CPC 6344). J. Style and splitting stigma toward the end of anthesis (CPC 6344). K. Portion of flower visited by ant (K CPC 857). [All photos of L. Averyanov and N.S. Khang, image correctionPublished as part of Vislobokov, Nikolay A., Тanaka, Noriyuki, Averyanov, Leonid V., Nguyen, Hiep Tien, Nuraliev, Maxim S. & Kuznetsov, Andrey N., 2014, Tupistra khangii (Asparagaceae), a new species from northern Vietnam, pp. 287-292 in Phytotaxa 175 (5) on page 290, DOI: 10.11646/phytotaxa.175.5.8, http://zenodo.org/record/514398
Nonlinear Mathematical Models of Costas Loops
No full textThis work is devoted to the development of nonlinear mathematical models of Costas loops. A Costas loop was invented in 1956 by John P. Costas of General Electric. Nowadays, a Costas loop is widely used in many applications including telecommunication devices, global positioning systems (GPS, GLONASS), medical
implants, mobile phones, and other gadgets. In contrast to the phase-locked loop (PLL) based circuit, the Costas loop is designed to simultaneously perform two tasks — carrier recovery and data demodulation. The direct application of a PLL to these tasks is possible, but it is not effective, because after superimposing the transmitted data and carrier signal, frequent changes of transmitted data require that a PLL constantly adjusts
itself. A Costas loop is designed in such a way that the transmitted data doesn’t affect transient processes and does not require frequent tuning. The requirement for simultaneous data demodulation and carrier recovery makes the
Costas loop-based devices multi-loop, multi-channel circuits with multiple outputs.
Also, in contrast to a PLL, the Costas loop has three non-linear elements.
All this makes the development of non-linear models of Costas loops a difficult
task. High-frequency signals, used in the modern devices, further complicate the
application of analytical methods and numerical simulation. This is due to the
fact that the transient time is greater than the signal’s periods by several orders
of magnitude. Furthermore, the behaviour of Costas circuits greatly depends on
the classes of signals involved. So, the development of non-linear mathematical
models of Costas loops that allow one to facilitate the application of analytical
methods and reduce the numerical simulation time is a relevant problem of
the practical significance. It is this problem that is considered and solved in the
present study.
In this work, nonlinear mathematical models of the classic Costas loop and
the Quadrature Phase Shift Keying (QPSK) Costas loop have been developed.
All theoretical results are rigorously proved. An effective numerical procedure
for the simulation of Costas loops based on the phase-detector characteristics is
proposed.
The results of the study have been published in 22 papers (8 of which are
indexed in Scopus)
On mean value properties involving a logarithm-type weight
No full textsummary:Two new assertions characterizing analytically disks in the Euclidean plane are proved. Weighted mean value property of positive solutions to the Helmholtz and modified Helmholtz equations are used for this purpose; the weight has a logarithmic singularity. The obtained results are compared with those without weight that were found earlier
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