scholarly journals Thermal radiation of extended particles with subwavelength transverse dimensions

2021 ◽  
pp. 17-25
Author(s):  
Anatoly Sviridov ◽  
Leonid Saginov
Keyword(s):  
Radiation Spectrum ◽  
Fundamental Difference ◽  
Cutoff Wavelength ◽  
Calculation Methods ◽  
Spectral Radiation ◽  
Radiation Fluxes ◽  
Spatial Modes ◽  
Coeffi Cients ◽  
Planck’S Law ◽  
Comparison Of The Results

The paper proposes a new method for calculating the integral and spectral radiation coeffi-cients of extended subwavelength particles (ESPs), which include micro and nanocylinders and parallelepipeds. Comparison of the results of calculations by the proposed method with the calculated and experimental data found in the literature is carried out. It is shown that with decrease in only the transverse dimensions of the ESP (from values much larger than λmax to values much smaller than max) from the radiation spectrum, which was originally de-scribed by Planck's law and contained modes with both polarization directed along the axis and with polarization directed perpendicular to the axis , modes with wavelengths exceeding λcutoff (λcutoff is the cutoff wavelength) and having polarization perpendicular to the longi-tudinal axis of the ESP will be gradually eliminated, while modes with wavelengths polarized along the ESP axis will always be present in the radiation spectrum of the ESP. When the transverse dimensions of the ESP become much less than λmax, then all modes with polariza-tion perpendicular to the axis will disappear from the emission spectrum of this ESP, and on-ly modes with longitudinal polarization will remain. This is a fundamental difference from the SPs considered earlier in [16, 17], where methods for calculating SPs as disks, spheres, cubes were proposed. All the proposed calculation methods use the formalism of the decom-position of radiation fluxes into spectral-spatial modes.

scholarly journals Solar Extreme and Far Ultraviolet Radiation Modeling for Aeronomic Calculations

2021 ◽  
Vol 13 (8) ◽  
pp. 1454
Author(s):  
Anatoliy A. Nusinov ◽  
Tamara V. Kazachevskaya ◽  
Valeriya V. Katyushina
Keyword(s):  
Ultraviolet Radiation ◽  
Input Parameter ◽  
Solar Spectrum ◽  
Upper Atmosphere ◽  
Model Calculations ◽  
Radiation Fluxes ◽  
Main Components ◽  
Comparison Of The Results ◽  
Far Ultraviolet ◽  
Radiation Modeling

Modeling the upper atmosphere and ionospheres on the basis of a mathematical description of physical processes requires knowledge of ultraviolet radiation fluxes from the Sun as an integral part of the model. Aeronomic models of variations in the radiation flux in the region of extreme (EUV) and far (FUV) radiation, based mainly on the data of the last TIMED mission measurements of the solar spectrum, are proposed. The EUVT model describes variations in the 5–105 nm spectral region, which are responsible for the ionization of the main components of the earth’s atmosphere. The FUVT model describes the flux changes in the 115–242 nm region, which determines heating of the upper atmosphere and the dissociation of molecular oxygen. Both models use the intensity of the hydrogen Lyman-alpha line as an input parameter, which can currently be considered as one of the main indices of solar activity and can be measured with relatively simpler photometers. A comparison of the results of model calculations with observations shows that the model error does not exceed 1–2% for the FUVT model, and 5.5% for EUVT, which is sufficient for calculating the parameters of the ionosphere and thermosphere.

scholarly journals An Analysis of the Impact of Valve Closure Time on the Course of Water Hammer

2016 ◽  
Vol 63 (1) ◽  
pp. 35-45 ◽  
Author(s):  
Apoloniusz Kodura
Keyword(s):  
Transient Flow ◽  
Pressure Change ◽  
Water Hammer ◽  
Valve Closure ◽  
Calculation Methods ◽  
New Methods ◽  
Closure Time ◽  
Physical Experiments ◽  
Comparison Of The Results ◽  
The Impact

Abstract The knowledge of transient flow in pressure pipelines is very important for the designing and describing of pressure networks. The water hammer is the most common example of transient flow in pressure pipelines. During this phenomenon, the transformation of kinetic energy into pressure energy causes significant changes in pressure, which can lead to serious problems in the management of pressure networks. The phenomenon is very complex, and a large number of different factors influence its course. In the case of a water hammer caused by valve closing, the characteristic of gate closure is one of the most important factors. However, this factor is rarely investigated. In this paper, the results of physical experiments with water hammer in steel and PE pipelines are described and analyzed. For each water hammer, characteristics of pressure change and valve closing were recorded. The measurements were compared with the results of calculations perfomed by common methods used by engineers - Michaud’s equation and Wood and Jones’s method. The comparison revealed very significant differences between the results of calculations and the results of experiments. In addition, it was shown that, the characteristic of butterfly valve closure has a significant influence on water hammer, which should be taken into account in analyzing this phenomenon. Comparison of the results of experiments with the results of calculations? may lead to new, improved calculation methods and to new methods to describe transient flow.

scholarly journals Thermal radiation ofsubwavelengthparticles

2021 ◽  
pp. 12-21
Keyword(s):  
Particle Size ◽  
Thermal Radiation ◽  
Electromagnetic Radiation ◽  
Particle Shape ◽  
Radiation Spectrum ◽  
Simple Scheme ◽  
Blue Region ◽  
Integral Radiation ◽  
Planck’S Law

A method is proposed for calculating the dependences of the emissivity of subwavelength parti-cles (SP) from various materials in the form of disks, spheres, cubes and cylinders on their sizes (D) and temperature (T), for cases when external electromagnetic radiation practically does not affect their temperature. For all the listed types of particles, the cutoff wavelengths λcutoffdepending on the size of the SP and the particle shape coefficients ξare determined. With a decrease in the particle size, from the radiation spectrum, which was originally described by Planck's law, wavelengths exceeding λcutoffare gradually excluded. This leads to a decrease in the integral radiation, a decrease in the emissivity and a shift of the radiation spectrum to the blue region. A simple scheme is also proposed for determining ε -the emission coefficients of the midrange according to the calculated graph ε (U), where: U = (ξ × D × T) / B; B is the con-stant of the Wien displacement formula.

A Rapid Radioisotope Dilution Technique for the Accurate Determination of the Cardiac Output

1968 ◽  
Vol 07 (01) ◽  
pp. 1-7
Author(s):  
Muhammad Razzak ◽  
Robert Botti ◽  
William MacIntyre
Keyword(s):  
Cardiac Output ◽  
Isotope Dilution ◽  
Accurate Determination ◽  
Differential Count ◽  
Stroke Index ◽  
Recording Device ◽  
Dilution Curve ◽  
Index Stroke Volume ◽  
Index Stroke ◽  
Comparison Of The Results

SummaryA pair of printing scalers was used to record the information obtained by external monitoring of the isotope dilution curve following the intravenous injection of radioiodinated human serum albumin. The first scaler gives the differential count rate of the curve at increments of one second, whereas the second integrates continuously the isotope dilution curve. This recording device enabled cardiac output determinations to be calculated rapidly at the bedside without any loss in accuracy.Using this method in 15 normal individuals, the cardiac output was found to be 6.13 ± 0.73 liters/minute (Mean ± 1 S.D.), with a cardiac index of 3.36 ± 0.35 liters/minute/m2. In the same group of normals, the stroke index (stroke volume/surface area) amounted to 50 ± 7.3 ml/beat/m2.Comparison of the results of this method with those obtained by integration of the entire isotope dilution curve by an IBM 1620 computer showed excellent agreement, proving the validity of the suggested technique.

Characterizing the convective heat exchange with plastic shading nets under natural arid conditions

2019 ◽  
pp. 11-20
Author(s):  
Ahmed M Abdel-Ghanya ◽  
Ibrahim M Al-Helal
Keyword(s):  
Wind Speed ◽  
Thermal Radiation ◽  
Convective Heat ◽  
Convective Heat Transfer Coefficient ◽  
Convective Heat Exchange ◽  
Radiative Properties ◽  
Wooden Frame ◽  
Arid Conditions ◽  
Air Temperatures ◽  
Radiation Fluxes

Plastic nets are extensively used for shading purposes in arid regions such as in the Arabian Peninsula. Quantifying the convection exchange with shading net and understanding the mechanisms (free, mixed and forced) of convection are essential for analyzing energy exchange with shading nets. Unlike solar and thermal radiation, the convective energy, convective heat transfer coefficient and the nature of convection have never been theoretically estimated or experimentally measured for plastic nets under arid conditions. In this study, the convected heat exchanges with different plastic nets were quantified based on an energy balance applied to the nets under outdoor natural conditions. Therefore, each net was tacked onto a wooden frame, fixed horizontally at 1.5-m height over the floor. The downward and upward solar and thermal radiation fluxes were measured below and above each net on sunny days; also the wind speed over the net, and the net and air temperatures were measured, simultaneously. Nets with different porosities, colors and texture structures were used for the study. The short and long wave’s radiative properties of the nets were pre-determined in previous studies to be used. Re and Gr numbers were determined and used to characterize the convection mechanism over each net. The results showed that forced and mixed convection are the dominant modes existing over the nets during most of the day and night times. The nature of convection over nets depends mainly on the wind speed, net-air temperature difference and texture shape of the net rather than its color and its porosity.

Challenges of the Crisis: How to Measure Sustainable Development?

2015 ◽  
pp. 147-160 ◽  
Author(s):  
S. Bobylev ◽  
N. Zubarevich ◽  
S. Solovyeva
Keyword(s):  
Sustainable Development ◽  
World Bank ◽  
Environmental Indicators ◽  
Calculation Methods ◽  
Basic Principles ◽  
The Sustainable Development ◽  
Development Index ◽  
Development Indicators ◽  
Sustainable Development Indicators ◽  
Adjusted Net Savings

The article emphasizes the fact that traditional socio-economic indicators do not reflect the challenges of sustainable development adequately, and this is particularly true for the widely-used GDP indicator. In this connection the elaboration of sustainable development indicators is needed, taking into account economic, social and environmental factors. For Russia, adaptation and use of concepts and basic principles of calculation methods for adjusted net savings index (World Bank) and human development index (UNDP) as integral indicators can be promising. The authors have developed the sustainable development index for Russia, which aggregates and allows taking into account balanced economic, social and environmental indicators.

Heart Rate Recovery Changes during Competition Period in High-Level Basketball Players

2018 ◽  
Vol 1 (80) ◽  
Author(s):  
Audrius Gocentas ◽  
Anatoli Landõr ◽  
Aleksandras Kriščiūnas
Keyword(s):  
Heart Rate ◽  
Heart Rate Recovery ◽  
Team Sports ◽  
Basketball Players ◽  
Coeffi Cients ◽  
Competition Period ◽  
Monitoring Training ◽  
Intense Training ◽  
High Level

Research background and hypothesis. Replete schedule of competitions and intense training are features of contemporary team sports. Athletes, especially the most involved ones, may not have enough time to recover. As a consequence, aggregated fatigue can manifest in some undesirable form and affect athlete’s performance and health.Research aim. The aim of this study was to evaluate the changes in heart rate recovery (HRR) and investigate possible relations with sport-specifi c measures of effi cacy in professional basketball players during competition season.Research methods. Eight male high-level basketball players (mean ± SD, body mass, 97.3 ± 11.33 kg; height 2.02 ± 0.067 m, and age 23 ± 3.12 years) were investigated. The same basketball specifi c exercise was replicated several times from September till April during the practice sessions in order to assess the personal trends of HRR. Heart rate monitoring was performed using POLAR TEAM SYSTEM. Investigated athletes were ranked retrospectively according to the total amount of minutes played and the coeffi cients of effi cacy. Research results. There were signifi cant differences in the trends of HRR between the investigated players. The most effective players showed decreasing trends of HRR in all cases of ranking.Discussion and conclusions. Research fi ndings have shown that the quality of heart rate recovery differs between basketball players of the same team and could be associated with sport-specifi c effi cacy and competition playing time.Keywords: adaptation, autonomic control, monitoring training.

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