ЭКСПЕРИМЕНТАЛЬНАЯ ВЕРИФИКАЦИЯ КОМПЬЮТЕРНОЙ МОДЕЛИ СИСТЕМЫ ОХЛАЖДЕНИЯ МОЩНОГО ПОЛУПРОВОДНИКОВОГО ПРИБОРА

A cooling system for powerful semi-conductor device (power -1 kW) consisting of a pin-type radiator and a body is considered in the paper. Cooling is carried out by forced convection of a coolant. Calculated values of temperatures on the radiator surface and experimentally measured values of temperatures in the same surface points have been compared in the paper. It has been shown that the difference between calculated and experimentally measured temperatures does not exceed 0,1-0,2 °C and it is comparable with experimental error value. The given results confirm correctness of a computer model.Рассматривается система охлаждения мощного полупроводникового прибора (мощность ~ 1 кВт), состоящая из штырькового радиатора и корпуса. Охлаждение осуществляется за счет вынужденной конвекции охлаждающей жидкости. Проводится сравнение расчетных значений температуры на поверхности радиатора с экспериментально измеренными в этих же точках значениями температуры. Показано, что разница между расчетными и экспериментальными значениями температуры не превышает 0,1–0,2 °С, что сопоставимо с величиной погрешности измерений. Данные результаты подтверждают корректность компьютерной модели.

АНАЛИЗ ТЕПЛОВЫХ СВОЙСТВ ЛИНЕЕК СВЕТОДИОДОВ МЕТОДОМ ПЕРЕХОДНЫХ ЭЛЕКТРИЧЕСКИХ ПРОЦЕССОВ

Increasing the solid lighting facilities operational energy-efficiency in the national economy of the Republic of Belarus is of current concern. The modern problems of energy-saving lighting are multifaceted and broad-ranging. It is particularly burning amidst the energy crisis and the world commercial slump. Thus, the lighting demands 10–13 % of the total electric energy consumption in Belarus. That is to say, there is a significant potential of energy saving in transition to energy-efficient lighting. The paper considers the issues of reliability and service period of the solid-state lighting devices created on the basis of lines of light-emitting-diodes (LED) produced by Paragon Semiconductor Lighting Technology Co., Ltd. The optoelectronic apparatuses reliability assessment is based on investigation of the development principles and deterioration mechanisms leading to failures of one kind or another. The deterioration causes ascertainment is indispensable for acting upon them later on and thus reducing the degradation speed and extent. One of the LED-devices deterioration main sources is the temperature overheat of the LED-chip active area. Therefore, techniques for evaluating the heat characteristics of solid lighting devices become the issue of the day. The article investigates thermal properties of high-capacity blue LED-lines by method of electrical transient processes. The authors calculate temperatures in the LED-lines active areas at various heat-dissipation conditions and injection currents values. They realize computer generated simulation of the heated lines thermal fields applying the ANSYS packet. The study concludes that out of the degree of temperature-distribution heterogeneity along the line impossibility of the line chip structural units thermal characteristics extraction arises based on all LEDs homogenized over the line temperature-time dependences. The paper indicates that one can with reasonable accuracy obtain the LED-lines thermal parameters employing the line representation with two equivalent RC-strings corresponding the thermal ways ‘LED active area – aluminium base’ and ‘aluminium base – environment’. For these areas thermal time constants, thermal resistances and thermal capacities are determined. Повышение энергоэффективности работы твердотельных осветительных устройств в народном хозяйстве Республики Беларусь является актуальной задачей. Современные проблемы энергоэффективного освещения многогранны и имеют широкий спектр. Особенно это актуально в условиях энергетического и мирового экономического кризиса. Так, на освещение в Беларуси расходуется 10–13 % от общего потребления электроэнергии. Таким образом, имеется значительный потенциал энергосбережения за счет перехода к энергоэффективному освещению. Рассмотрены вопросы надежности и долговечности работы твердотельных осветительных устройств, созданных на основе светодиодных линеек фирмы Paragon Semiconductor Lighting Technology Co., Ltd. Оценка надежности оптоэлектронных приборов базируется на исследовании закономерностей развития механизмов деградации, приводящих к отказам того или иного типа. Выяснение причин деградации необходимо, чтобы затем, целенаправленно воздействуя на них, уменьшить скорость и величину деградации. Одной из основных причин деградации светодиодных устройств является температурный перегрев активной области светодиодного чипа. Поэтому актуальными становятся методы оценки тепловых характеристик твердотельных осветительных устройств. В статье исследованы тепловые свойства мощных синих светодиодных линеек методом переходных электрических процессов. Рассчитаны температуры активной области светодиодов в линейках при различных условиях теплоотвода и значениях токов инжекции. Проведено компьютерное моделирование тепловых полей линеек при нагреве с использованием пакета ANSYS. Установлено, что из степени неоднородности распределения температуры вдоль линейки следует невозможность выделения тепловых свойств элементов структуры чипов линейки на основе усредненных по всем светодиодам временных зависимостей температуры. Показано, что тепловые параметры линеек светодиодов с достаточной точностью можно получить, используя представление линейки только двумя эквивалентными RC-цепочками, соответствующими тепловым путям «активная область светоизлучающего светодиода – алюминиевая подложка» и «алюминиевая подложка – окружающая среда». Для данных областей определены тепловые постоянные времени, тепловые сопротивления и теплоемкости.

СПЕКТРАЛЬНОЕ РАСПРЕДЕЛЕНИЕ СПОНТАННОЙ ЭЛЕКТРОЛЮМИНЕСЦЕНЦИИ ЗЕЛЕНЫХ СВЕТОИЗЛУЧАЮЩИХ ДИОДОВ

Metrological possibilities of a specialised measuring complex with which help electroluminescence spectra (EL) light-emitting diodes (LED) are received are studied. The analysis is carried out and forms of spectra of EL LED with a single quantum hole on the basis of model considering penetration into twodimensional active layer InGaN of electric field from barrier layers GaN adjoining to it and AlGaN are investigated. By means of the given model values of effective width of the forbidden zone, Fermi's level, parametre of a exponential tail of density of a condition are received.Изучены метрологические возможности специализированного измерительного комплекса, с помощью которого получены спектры электролюминесценции (ЭЛ) светоизлучающих диодов (СИД). Проведен анализ и исследованы формы спектров ЭЛ СИД с одиночной квантовой ямой на основе модели учитывающей проникновение в двухмерный активный слой InGaN электрического поля от прилегающих к нему барьерных слоев GaN и AlGaN. С помощью данной модели получены значения эффективной ширины запрещенной зоны, уровня Ферми, параметра экспоненциального хвоста плотности состояния

EXPERIMENTAL VERIFICATION OF COMPUTER MODEL OF COOLING SYSTEM FOR POWERFUL SEMI- CONDUCTOR DEVICE

A cooling system for powerful semi-conductor device (power -1 kW) consisting of a pin-type radiator and a body is considered in the paper. Cooling is carried out by forced convection of a coolant. Calculated values of temperatures on the radiator surface and experimentally measured values of temperatures in the same surface points have been compared in the paper. It has been shown that the difference between calculated and experimentally measured temperatures does not exceed 0,1-0,2 °C and it is comparable with experimental error value. The given results confirm correctness of a computer model

Frequency response areas of neurons in the mouse inferior colliculus. III. Time-domain responses: Constancy, dynamics, and precision in relation to spectral resolution, and perception in the time domain.

The auditory midbrain (central nucleus of inferior colliculus, ICC) receives multiple brainstem projections and recodes auditory information for perception in higher centers. Many neural response characteristics are represented in gradients (maps) in the three-dimensional ICC space. Map overlap suggests that neurons, depending on their ICC location, encode information in several domains simultaneously by different aspects of their responses. Thus, interdependence of coding, e.g. in spectral and temporal domains, seems to be a general ICC principle. Studies on covariation of response properties and possible impact on sound perception are, however, rare. Here, we evaluated tone-evoked single neuron activity from the mouse ICC and compared shapes of excitatory frequency-response areas (including strength and shape of inhibition within and around the excitatory area; classes I, II, III) with types of temporal response patterns and first-spike response latencies. Analyses showed covariation of sharpness of frequency tuning with constancy and precision of responding to tone onsets. Highest precision (first-spike latency jitter < 1 ms) and stable phasic responses throughout frequency-response areas were the quality mainly of class III neurons with broad frequency tuning, least influenced by inhibition. Class II neurons with narrow frequency tuning and dominating inhibitory influence were unsuitable for time domain coding with high precision. The ICC center seems specialized rather for high spectral resolution (class II presence), lateral parts for constantly precise responding to sound onsets (class III presence). Further, the variation of tone-response latencies in the frequency-response areas of individual neurons with phasic, tonic, phasic-tonic, or pauser responses gave rise to the definition of a core area, which represented a time window of about 20 ms from tone onset for tone-onset responding of the whole ICC. This time window corresponds to the roughly 20 ms shortest time interval that was found critical in several auditory perceptual tasks in humans and mice

ThermControl Project. Optimized cooling systems for rail and hybrid vehicles Final report

SIGLEAvailable from TIB Hannover: F04B690 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung und Forschung (BMBF), Bonn (Germany)DEGerman

ANALYSIS OF THERMAL PROPERTIES OF THE LED-LINES BY METHOD OF ELECTRICАL TRANSIENT PROCESSES

Increasing the solid lighting facilities operational energy-efficiency in the national economy of the Republic of Belarus is of current concern. The modern problems of energy-saving lighting are multifaceted and broad-ranging. It is particularly burning amidst the energy crisis and the world commercial slump. Thus, the lighting demands 10–13 % of the total electric energy consumption in Belarus. That is to say, there is a significant potential of energy saving in transition to energy-efficient lighting. The paper considers the issues of reliability and service period of the solid-state lighting devices created on the basis of lines of light-emitting-diodes (LED) produced by Paragon Semiconductor Lighting Technology Co., Ltd. The optoelectronic apparatuses reliability assessment is based on investigation of the development principles and deterioration mechanisms leading to failures of one kind or another. The deterioration causes ascertainment is indispensable for acting upon them later on and thus reducing the degradation speed and extent. One of the LED-devices deterioration main sources is the temperature overheat of the LED-chip active area. Therefore, techniques for evaluating the heat characteristics of solid lighting devices become the issue of the day. The article investigates thermal properties of high-capacity blue LED-lines by method of electrical transient processes. The authors calculate temperatures in the LED-lines active areas at various heat-dissipation conditions and injection currents values. They realize computer generated simulation of the heated lines thermal fields applying the ANSYS packet. The study concludes that out of the degree of temperature-distribution heterogeneity along the line impossibility of the line chip structural units thermal characteristics extraction arises based on all LEDs homogenized over the line temperature-time dependences. The paper indicates that one can with reasonable accuracy obtain the LED-lines thermal parameters employing the line representation with two equivalent RC-strings corresponding the thermal ways ‘LED active area – aluminium base’ and ‘aluminium base – environment’. For these areas thermal time constants, thermal resistances and thermal capacities are determined

SPECTRAL DISTRIBUTION OF SPONTANEOUS ELECTROLUMINESCENCE IN GREEN LIGHT EMITTING DIODES AT DIFFERENT EXCITATION LEVELS

Metrological possibilities of a specialised measuring complex with which help electroluminescence spectra (EL) light-emitting diodes (LED) are received are studied. The analysis is carried out and forms of spectra of EL LED with a single quantum hole on the basis of model considering penetration into twodimensional active layer InGaN of electric field from barrier layers GaN adjoining to it and AlGaN are investigated. By means of the given model values of effective width of the forbidden zone, Fermi's level, parametre of a exponential tail of density of a condition are received