Existence of radial stationary solutions for a system in combustion theory

In this paper, we construct radially symmetric solutions of a nonlinear noncooperative elliptic system derived from a model for flame balls with radiation losses. This model is based on a one step kinetic reaction and our system is obtained by approximating the standard Arrehnius law by an ignition nonlinearity, and by simplifying the term that models radiation. We prove the existence of 2 solutions using degree theory

ВОЗМОЖНОСТИ ИСПОЛЬЗОВАНИЯ СВЕТОВЫХ ЛУЧЕЙ ВИДИМОГО ДИАПАЗОНА В СИСТЕМАХ СКРЫТОЙ ПЕРЕДАЧИ ИНФОРМАЦИИ

Security In the paper some aspects of visible light pulses using for hidden information transmitting are considered. We have investigated perception of the human vision to visual light pulses which have different power and frequency. It is established that pulsed light source becomes invisible at certain ratio of radiating light stream and ambient light level (background lighting (BL)). For example, in the case of background lighting E = 400 lx light pulses following with frequency 50 Hz are invisible when their power is less than 0.12 W. In the paper we represented experimental frequency dependence of the power of light pulses which are invisible for human eye at BL preset level.To eliminate the influence of distracting and masking factors (for example, BL pulsations) we offer to choose LED matrixes powered by stabilized adjustable DC power supply unit as an optimal BL source. Based on experimental data about current and temperature dependences of light stream power and LED matrix radiation spectra we developed a method of assignment of BL level by changing LED current. Approximating equation for dependence of light stream quantity versus LED current in the case of thermostatting is obtained. Temperature self-regulation effect of the heater, which has positive temperature coefficient of resistance, can satisfactorily solve the problem of temperature stabilization of LED background lighting source. In the case of thermostat heater made from material with positive temperature coefficient of resistance 0.48 K-1 the change of LED matrix temperature was 7 times less than without thermostat.To provide research in wide frequency and duration ranges of pulse sequences (10–3–103 Hz and 10–7–1 s) a pulse generator was developed and made using microcontroller PIC18F2550.В работе рассмотрены основные аспекты использования световых импульсов видимого диапазона для скрытой передачи информации. Исследовано восприятие человеческим зрением световых импульсов видимого диапазона различной мощности и частоты следования. Установлено, что источник импульсного света становится невидимым при определенном соотношении мощности излучаемого светового потока и уровня освещенности окружающих его предметов (фонового освещения (ФО)). Например, при фоновом освещении Е = 400 лк световые импульсы, следующие с частотой 50 Гц, невидимы при их мощности меньше 0,12 Вт. Приведена экспериментальная частотная зависимость мощности световых импульсов, не видимых для человеческого зрения при заданном уровне ФО.С целью устранения влияния отвлекающих или маскирующих факторов (например, пульсаций ФО) в качестве оптимального источника засветки выбраны светодиодные матрицы при их питании от стабилизированного регулируемого источника постоянного тока. На основе экспериментальных данных о токовой и температурной зависимостях мощности светового потока и спектров излучения светодиодных матриц предложена методика задания уровня фонового излучения путем изменения величины тока светодиода. Получено аппроксимирующее уравнение зависимости величины светового потока от тока светодиода при условии термостатирования светодиода. Эффект саморегулирования температуры нагревателя с положительным температурным коэффициентом сопротивления (ТКС) позволил вполне удовлетворительно решить вопрос стабилизации температуры светодиодного источника ФО. В случае нагревателя термостата, изготовленного из материала с положительным ТКС = 48%·К-1, изменение температуры светодиодной матрицы было практически в 7 раз меньше, чем без термостата.Для проведения исследований в широком частотном интервале следования световых импульсов разработан и изготовлен генератор импульсов на микроконтроллере PIC18F2550 который обеспечивает возможность формирования импульсов частотой от 10–3 до 103 Гц длительностью от 10–7 до 1с

On Hygia opaca (Uhler), H. lativentris (Motschulsky) and H. obscura (Dallas) (Heteroptera: Coreidae).

The following new synonymy is established: Hygia opaca (Uhler, 1860) = H. japonica Ahmad, 1969, syn. n., H. lativentris (Motschulsky, 1866) = H. touchei (Distant, 1901), syn. n. Hygia opaca opaca sensu Ahmad, 1969 is a misidentification of H. lativentris (Motschulsky, 1866), the latter species does not belong to the subgenus Microcolpura. The records of H. obscura (Dallas, 1852) from Korea and China are considered mistakes

On Oscillatory Instability in Convective Burning of Gas-Permeable Explosives

The experimentally known phenomenon of oscillatory instability in convective burning of porous explosives is discussed. A simple phenomenological model accounting for the ejection of unburned particles from the consolidated charge is formulated and analyzed. It is shown that the post-front hydraulic resistance induced by the ejected particles provides a mechanism for the oscillatory burning

CAPABILITIES OF APPLYING VISIBLE LIGHT RAYS IN THE SYSTEMS OF HIDDEN INFORMATION TRANSMITTING

Security In the paper some aspects of visible light pulses using for hidden information transmitting are considered. We have investigated perception of the human vision to visual light pulses which have different power and frequency. It is established that pulsed light source becomes invisible at certain ratio of radiating light stream and ambient light level (background lighting (BL)). For example, in the case of background lighting E = 400 lx light pulses following with frequency 50 Hz are invisible when their power is less than 0.12 W. In the paper we represented experimental frequency dependence of the power of light pulses which are invisible for human eye at BL preset level.To eliminate the influence of distracting and masking factors (for example, BL pulsations) we offer to choose LED matrixes powered by stabilized adjustable DC power supply unit as an optimal BL source. Based on experimental data about current and temperature dependences of light stream power and LED matrix radiation spectra we developed a method of assignment of BL level by changing LED current. Approximating equation for dependence of light stream quantity versus LED current in the case of thermostatting is obtained. Temperature self-regulation effect of the heater, which has positive temperature coefficient of resistance, can satisfactorily solve the problem of temperature stabilization of LED background lighting source. In the case of thermostat heater made from material with positive temperature coefficient of resistance 0.48 K-1 the change of LED matrix temperature was 7 times less than without thermostat.To provide research in wide frequency and duration ranges of pulse sequences (10–3–103 Hz and 10–7–1 s) a pulse generator was developed and made using microcontroller PIC18F2550