Characteristics dependence of the silicon photoelectronic multipliers on temperature

The characteristics dependence on the ambient temperature for three types of silicon photoelectronic multipliers have been studied in this research. The prototypes of Si-photoelectronic multipliers with a p+–p–n+ structure produced by JSC Integral (Republic of Belarus), serially produced silicon photoelectronic multipliers KETEK РМ3325 and ON Semi FC 30035 have been used as objects of research. We present the setup diagram and research technique. Measurements of the photocurrent magnitude versus the illumination intensity, calculations of the critical and threshold intensities, and the dynamic range have been performed. We also present the photocurrent dependences on the illumination intensity at different ambient temperatures. As it was found, these dependences have a linear section, the length of which characterizes the critical intensity value, and the inclination angle of the linear section to the intensity axis characterizes the photodetector sensitivity to optical radiation. It has been determined that the temperature increase leads to an increase in the critical intensity value and to a decrease in the sensitivity value. We present the dependences of the threshold intensity on the overvoltage at different ambient temperatures. The dependence of the threshold intensity on overvoltage is most strongly pronounced when the supply voltage is below the breakdown voltage. It was found that the threshold intensity is increased with the temperature increase and the threshold intensity dependence on the temperature is the same for all investigated photodetectors. It was found that the dynamic range value is decreased with the temperature increase, which is caused by a more significant change in the threshold intensity as compared to the critical one. The results given in this article can be applied when developing and designing the tools and devices for recording optical radiation based on silicon photoelectronic multipliers.

Identification of acoustic emission sources under cyclic loading of the polymer composite material used in shipbuilding

Данная работа посвящена исследованию механизмов накопления повреждений в полимерном композиционном материале (ПКМ) в ходе усталостного нагружения. Механическое испытание образца стеклопластика проводили циклическим растяжением в сопровождении регистрации акустической эмиссии (АЭ). Для зарегистрированных сигналов АЭ рассчитывались спектры Фурье и использовались для кластеризации самоорганизующейся картой Кохонена (SOM). Полученные центроиды, для снижения количества анализируемых кластеров, разделяли на кластеры методом k-средних. Кластеры второго этапа кластеризации соотносились с типами повреждений в структуре ПКМ. Рассчитывались периоды критической интенсивности регистрации различных типов образующихся повреждений. Дополнительно проведён анализ пиковых частот уровней вейвлет декомпозиции Добеши 14 сигналов АЭ. На основании проведенных методов анализа данных АЭ описаны протекающие процессы разрушения в образце ПКМ. This work is aimed the study the mechanisms of damage accumulation in a polymer composite material (PCM) during fatigue loading. Mechanical test of a fiberglass sample was done by cyclic tension with acoustic emission (AE) registration. The Fourier spectra were calculated for the recorded AE signals and used for clustering with a self-organizing Kohonen map (SOM). The obtained centroids, in order to reduce the number of analyzed clusters, were divided into clusters by the k-means method. Clusters of the second stage clustering correlated with the types of damage in the structure of the PCM. The periods of the critical intensity of registration of various types of formed damages were calculated. Additionally, the peak frequencies of the levels of Daubechies 14 wavelet decomposition of AE signals was analyzed. Based on the methods for analyzing the AE data, the processes of destruction in the PCM sample are described.

Generalized disconnection exponents

We introduce and compute the generalized disconnection exponents$$\eta _\kappa (\beta )$$ η κ ( β ) which depend on $$\kappa \in (0,4]$$ κ ∈ ( 0 , 4 ] and another real parameter $$\beta $$ β , extending the Brownian disconnection exponents (corresponding to $$\kappa =8/3$$ κ = 8 / 3 ) computed by Lawler, Schramm and Werner (Acta Math 187(2):275–308, 2001; Acta Math 189(2):179–201, 2002) [conjectured by Duplantier and Kwon (Phys Rev Lett 61:2514–2517, 1988)]. For $$\kappa \in (8/3,4]$$ κ ∈ ( 8 / 3 , 4 ] , the generalized disconnection exponents have a physical interpretation in terms of planar Brownian loop-soups with intensity $$c\in (0,1]$$ c ∈ ( 0 , 1 ] , which allows us to obtain the first prediction of the dimension of multiple points on the cluster boundaries of these loop-soups. In particular, according to our prediction, the dimension of double points on the cluster boundaries is strictly positive for $$c\in (0,1)$$ c ∈ ( 0 , 1 ) and equal to zero for the critical intensity $$c=1$$ c = 1 , leading to an interesting open question of whether such points exist for the critical loop-soup. Our definition of the exponents is based on a certain general version of radial restriction measures that we construct and study. As an important tool, we introduce a new family of radial SLEs depending on $$\kappa $$ κ and two additional parameters $$\mu , \nu $$ μ , ν , that we call radial hypergeometric SLEs. This is a natural but substantial extension of the family of radial $$\hbox {SLE}_\kappa (\rho )s$$ SLE κ ( ρ ) s .

Calculation the intensity of aerobic exercise in fitness

According to the vast majority of experts, aerobic exercises are basic in fitness. Their effectiveness in the practice involves the rational regulation of load parameters, one of which is the intensity of exercises. However as practice shows the proposed methods for determining the necessary intensity of aerobic exercises do not quite adequately take into account the individual characteristics - age and fitness level. The purpose of the research is to evaluate methods for calculating intensity of aerobic exercise in fitness. In our studies we proceeded from the fact that calculation methods should consider two main trends. At the aging heart rate at rest slightly rises, and the upper pulse during exercises decreases. A higher fitness connected with significant decrease in heart rate at rest and an increase in its upper rate at critical intensity (expanding the range of heart rate during exercise). According to the vast majority of specialists, aerobic exercise is basic in wellness physical culture. Their effective application in the practice of wellness work implies rational regulation of the load parameters, one of which is the intensity of work. As a result the analysis of real situations it was demonstrated that the calculation intensity of aerobic activity according to heart rate indicators using formulas that take into account only the age of the practitioners is applicable in a certain age range (up to about 50-55 years). As age increases the correctness of such calculations decreases and loses its meaning in certain point due to the fact that calculated indicators of heart rate during exercises may be less than those at rest. Karvonen formula which takes into account the individual level of physical fitness for heart rate at rest is more accurate for determining heart rate in aerobic exercise. Its using allows us more correctly determine the lower pulse during exercises declining it because decrease in resting heart rate. However this formula also declining the upper pulse during exercises, although it should increase as the cardiovascular system improves.

Formation and morphology of anomalous solar circular polarization

Context. The morphology of spectral line polarization is the most valuable observable to investigate the magnetic and dynamic solar atmosphere. However, in order to develop solar diagnosis, it is fundamental to understand the different kinds of anomalous solar signals that are routinely found in linear and circular polarization (LP,CP). Aims. We aim to explain and characterize the morphology of solar CP signals considering nonlocal thermodynamical equilibrium (NLTE) effects. Methods. An analytical two-layer model of the polarized radiative transfer equation is developed and used to solve the NLTE problem with atomic polarization in a semi-parametric way. The potential of the model for reproducing anomalous CP is shown with detailed calculations and examples. A new approach based on the zeroes of polarization signals is developed to explain their morphology. Results. We have obtained a comprehensive model that insightfully describes the formation of solar polarization with certain precision without sacrificing key physical ingredients or resorting to complex atmospheric models. The essential physical behavior of dichroism and atomic orientation has been described, introducing the concepts of dichroic inversion, neutral and reinforcing medium, critical intensity spectrum, and critical source function. We show that the zero-crossings of the CP spectrum are useful to classify its morphology and understand its formation. This led to identification and explanation of the morphology of the seven most characteristic CP signals that a single (depth-resolved) scattering layer can produce. We find that a minimal number of two magnetic layers along the line of sight is required to fully explain anomalous solar CP signals and that the morphology and polarity of Stokes V depends on magnetic, radiative, and atomic “polarities”. Some implications of these results are presented through a preliminary modeling of anomalous CP signals in the Fe I 1564.8 nm and Na I D lines.

Application of critical intensity model during slide board skating

Critical cadence (CC), critical power (CP), and the work above CP (W′) were determined from linear and hyperbolic modelling during skating on a slide board, in 13 well-trained speed skaters. Three to 4 trials to exhaustion were used for the fitting. CC from the linear model was higher than the hyperbolic model (56.0 ± 4.8 vs 55.0 ± 4.5 push-offs/min, p = 0.01). No differences were found for CP and W′ parameters from the models analyzed.

Physical Load Intensity in Standard and Latin American Sports Dancing Programmes for Juvenile Dancers

Research background and hypothesis. Sports dances at the contest intensity demand great athletic fitness and functional capacity from dancers We still lack research about changes in the heart rate in the group of juvenile dancers’ while dancing Standard and Latin American dances. The present study aims at verifying the hypothesis that while juvenile dancers dancing contest programmes, the heart rate is changeable and can reach to 160–190 beats/min and above, sports dancers consume much energy.Research aim was to investigate changes in the heart rate and energy consumption in the group of juvenile dancers while dancing Standard and Latin American dances. Research methods. The research participants were 16 dancers (8 girls and 8 boys). The age of girls was 9.88 (0.83) years, and that of boys – 9.86 (1.07) years. We established changes in the heart rate dancing Standard and Latin American dances. During continuous dancing we registered the heart rate using “Polar S 610” Heart Rate Monitor (Finland) with computer data registering system. According to the indices received from the heart rate monitor we calculated the average, maximal and minimal heart rate values and energy consumption (kcal) during the period of sports dancing programme. Research results. The data of HR analysis showed that during a 10-min model practice session dancing Standard and Latin American dances, the heart rate which remains the longest is 160–190 beats/min. During Latin American dances, energy outlay for girls was greater than that for boys (p < 0.05), but lower compared to those when the girls danced the Standard programme. Discussion and conclusions. In contest programmes of sports dancing, physical loads are of changing intensities and thus they have a big impact on the cardiovascular system of young dancers. At the threshold of anaerobic intensity, some moments of the dance are performed at greater intensity then the anaerobic threshold, and even critical intensity limit is reached.Keywords Standard dances, Latin American dances, intensity of physical load, heart rate, energy consumption.