1,294 research outputs found
Development of the algorithm for aircraft control at inaccurate measurement of the state vector and variable accuracy parameter
A parametric method of the synthesis of control in the closed circuit, taking into account explicitly generalized error of the inertial module, is presented. The law of control in the form of analytical formulas is typically assigned to the control program and does not change during flight of an unmanned aerial vehicle. This decreases the capabilities of the autonomous flight control system to overcome control errors, which occur for various reasons. To verify assumptions about a possibility of improving the accuracy of an aerial vehicle control by the data of the strapdown inertial navigation system on a certain time interval of autonomous operation, the calculation experiment was conducted with the use of the developed software complex, simulating operation of the automatic flight control system. Parametrization of the law of control is considered as the main contribution (the outcome). Introduction of the parameter made it possible to decrease a negative impact of measurement errors and other disturbing factors on accuracy of reaching by the point of flight destination. Through computer modeling, it was shown that it is possible to decrease the impact of a generalized measurement error on generation of values of control functions by changing the value of the parameter. Analytical expressions for the estimation of accuracy of automatic control at the known generalized error of the inertial module and limited disturbing influences were obtained. After analyzing the influence of these factors on accuracy of the object control, a set of recommendations on selection of a variable parameter of synthesis of control depending on precision level of the sensors, used in the inertial module of measuring sensors, was generated.Розглянуто розв’язання термінальної задачі управління та синтезований параметризований закон управління в аналітичному вигляді, який залежить від змінного параметра глибини прогнозу. Досліджено особливості впливу величини параметра управління на точність досягнення кінцевої точки, дані рекомендації з вибору параметра для нівелювання помилки інерційних вимірювань. Синтез управління здійснюється методом переслідування ведучої точки за інформацією, отриманою інтегруванням вимірювань фактичного прискорення і містить помилку, характерну для акселерометрів
On the isospin dependence of the mean spin-orbit field in nuclei
By the use of the latest experimental data on the spectra of Sb and
Sn and on the analysis of properties of other odd nuclei adjacent to
doubly magic closed shells the isospin dependence of a mean spin-orbit
potential is defined. Such a dependence received the explanation in the
framework of different theoretical approaches.Comment: 52 pages, Revtex, no figure
Electromagnetically induced switching of ferroelectric thin films
We analyze the interaction of an electromagnetic spike (one cycle) with a
thin layer of ferroelectric medium with two equilibrium states. The model is
the set of Maxwell equations coupled to the undamped Landau-Khalatnikov
equation, where we do not assume slowly varying envelopes. From linear
scattering theory, we show that low amplitude pulses can be completely
reflected by the medium. Large amplitude pulses can switch the ferroelectric.
Using numerical simulations and analysis, we study this switching for long and
short pulses, estimate the switching times and provide useful information for
experiments
Metastability and Nucleation for the Blume-Capel Model. Different mechanisms of transition
We study metastability and nucleation for the Blume-Capel model: a
ferromagnetic nearest neighbour two-dimensional lattice system with spin
variables taking values in -1,0,+1. We consider large but finite volume, small
fixed magnetic field h and chemical potential "lambda" in the limit of zero
temperature; we analyze the first excursion from the metastable -1
configuration to the stable +1 configuration. We compute the asymptotic
behaviour of the transition time and describe the typical tube of trajectories
during the transition. We show that, unexpectedly, the mechanism of transition
changes abruptly when the line h=2*lambda is crossed.Comment: 96 pages, 44 tex-figures, 7 postscript figure
Spin ice in a field: quasi-phases and pseudo-transitions
Thermodynamics of the short-range model of spin ice magnets in a field is
considered in the Bethe - Peierls approximation. The results obtained for
[111], [100] and [011] fields agrees reasonably well with the existing
Monte-Carlo simulations and some experiments. In this approximation all
extremely sharp field-induced anomalies are described by the analytical
functions of temperature and applied field. In spite of the absence of true
phase transitions the analysis of the entropy and specific heat reliefs over
H-T plane allows to discern the "pseudo-phases" with specific character of spin
fluctuations and define the lines of more or less sharp "pseudo-transitions"
between them.Comment: 18 pages, 16 figure
Профиль пациента со вторичной глаукомой
To date, there have been no studies in the Russian Federation analyzing the territorial prevalence of secondary glaucoma (SG). The reasons for this lie in the specifics of providing epidemiological reports on the incidence of this pathology, staff shortage in the budgetary health care system, lack of clinical interest of researchers in thisт form of the disease, for example due to the severity of its course, etc. At the same time, secondary glaucoma is one of the most severe glaucoma forms, which tends to progress and is difficult to treat with drugs or surgery. The high occurrence of SG (6–22%) worldwide and the risk of losing visual function make it important to continue studying this pathology. The varying occurrence of SG is determined by numerous factors, such as etiology of the disease, demographic and territorial features of the region, educational level, cultural and economic characteristics, patients' awareness and competence. The level of ophthalmologic services, such as qualification of the attending physicians, and the types of glaucoma surgeries that can be performed in the region also play an important role. Considering the relevance of this problem, the aim of this literature review is to determine the epidemiological characteristics of the disease in patients with secondary glaucoma. В настоящее время в Российской Федерации отсутствуют исследования, отражающие территориальную распространенность вторичной глаукомы (ВГ). Причины этого кроются в особенностях предоставления эпидемиологических отчетов по заболеваемости данной патологией, кадровым дефицитом в бюджетном звене здравоохранения, недостатком клинического интереса исследователей к данной форме заболевания, например, в силу тяжести ее течения и т. д. Между тем, ВГ является одной из наиболее тяжелых форм глаукомы, с трудом поддающихся как медикаментозному, так и хирургическому лечению, и имеет склонность к прогрессированию. Высокая частота заболеваемости ВГ (6–22 %) во всем мире и риск потери зрительных функций обусловливают важность изучения данной патологии. Различная распространенность ВГ обусловлена многочисленными факторами, такими как этиология развития заболевания, демографические и территориальные особенности региона, уровень образования, культурные, экономические особенности, осведомленность и компетентность пациентов. Важен также уровень офтальмологических услуг, таких как квалификация лечащего врача и выполняемые в регионе антиглаукомные операции. Учитывая актуальность данной проблемы, целью данного литературного обзора является определение эпидемиологических характеристик заболевания у пациентов с ВГ
Exclusonic Quasiparticles and Thermodynamics of Fractional Quantum Hall Liquids
Quasielectrons and quasiholes in the fractional quantum Hall liquids obey
fractional (including nontrivial mutual) exclusion statistics. Their statistics
matrix can be determined from several possible state-counting scheme, involving
different assumptions on statistical correlations. Thermal activation of
quasiparticle pairs and thermodynamic properties of the fractional quantum Hall
liquids near fillings ( odd) at low temperature are studied in the
approximation of generalized ideal gas. The existence of hierarchical states in
the fractional quantum Hall effect is shown to be a manifestation of the
exclusonic nature of the relevant quasiparticles. For magnetic properties, a
paramagnetism-diamagnetism transition appears to be possible at finite
temperature.Comment: latex209, REVTE
Search for elementary particles bearing a magnetic charge: an experimental design in the from of a modified variant
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