Total Radiation Power Research Articles

A simple estimation of TRP and radiation pattern for mobile antennas using planar near-field scanning method

An estimation method for the total radiation power (TRP) and radiation pattern of mobile antennas embedded in mobile phones using a planar near-field scanning method is proposed. The tangential magnetic fields on both front and rear faces of a mobile phone are measured both in magnitude and phase using a dual-probing technique in the time-domain. Moreover, for accurately obtaining the phase information from the measured data in the time-domain, a reliable triggering technique is introduced. The far-field is calculated by using the near-field to far-field transformation based on the equivalent principle and the image method. The calculated TRP and radiation pattern are validated by comparison with the measured TRP and radiation pattern in an authorized anechoic chamber, and good agreement has been achieved. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1437–1443, 2016

Temperature and radiative characteristics of cylindrical porous Ni–Al burners

Premixed gas combustion in cylindrical porous radiant burners with different thickness of the porous layer made by combustion synthesis is considered. Temperature and radiative characteristics of porous burners are studied experimentally. Experimental results demonstrate existence of two different combustion regimes, external and internal regimes of combustion, observed at the same values of gas flow rate and methane–air mixture composition. Depending on initial conditions one of these combustion regimes is established. Dependencies of porous-shell temperature, total radiation power and radiation efficiency on the firing rate and mixture composition are obtained for both internal and external combustion regimes. It is found that the internal combustion mode is characterized by higher temperatures of the outer burner surface, higher thermal radiation power and radiation efficiency, as well as more uniform glow of the porous medium compared to the external combustion mode.

Branestrahlung: Radiation in the particle-brane collision

We calculate the radiation accompanying gravitational collision of the domain wall and the point particle in five-dimensional spacetime. This process, which can be regarded as brane-particle bremsstrahlung, here called {\it branestrahlung}, has unusual features. Since the brane has intrinsic dynamics, it gets excited in the course of collision, and, in particular, at the moment of perforation the shock branon wave is generated, which then expands with the velocity of light. Therefore, apart from the time-like source, whose radiation can be computed in a standard way, the total radiation source contains a light-like part whose retarded field is quite non-trivial, exhibiting interesting retardation and memory effects. We analyze this field in detail, showing that, contrary to the claims that the light-like sources should not radiate at all, the radiation is non-zero and has classically divergent spectrum. We estimate the total radiation power introducing appropriate cutoffs. In passing, we explain how the sum of the non-local (with the support inside the light cone) and the local (supported on the cone) singular parts of the Green's function of the five-dimensional d'Alembert equation together define a regular functional.

The high‐energy view of young radio sources: X‐ray and gamma‐ray observations

AbstractAccording to theoretical predictions, young extragalactic radio sources may release a significant fraction of their total radiative power in the high‐energy domain. X‐ray emission is expected from the central active galactic nucleus (AGN), and from the extended radio components, jet, hot spots, and lobes. The X‐rays should also trace the interactions of the radio source with its environment, and reveal to us how the young source clears its way out of the host galaxy and finally reaches the giant stage. Observational campaigns with Chandra and XMM‐Newton telescopes have confirmed that young radio sources are indeed relatively X‐ray luminous. Recently, efforts have been undertaken to obtain a complete X‐ray view of the whole population of young sources, focusing on the youngest and faintest objects. At the same time, the study of the X‐ray properties of the samples of quasars and galaxies provides us with clues on the nature of the observed high‐energy emission. In specific cases, X‐ray and multi‐wavelength data allow for a direct test of the different models. A detection in the y‐ray band would represent a robust proof of a non‐thermal, high‐energy component and the launch of the Fermi telescope has opened the hunt to young radio sources in the y‐ray window. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Light Emission near a Gradient Metasurface

Gradient metasurfaces have recently emerged as a powerful tool for the control of externally incident optical wavefronts. Here we present a theoretical study showing how they can also dramatically modify the radiation properties of light emitters located in their near-field zone. First, the spontaneous emission decay of a dipole source can be greatly accelerated through near-field interactions involving evanescent waves at the metasurface, by an amount that depends on the dipole lateral position in an oscillatory fashion. Second, as a result of these interactions, highly asymmetric directional radiation patterns can be produced in the far field, with broad geometrical tunability of the angle of peak emission. Furthermore, the total output radiation power can be increased in the case of low-efficiency emitters or quenched in favor of directional excitation of surface waves depending on the metasurface phase gradient. These phenomena could not be explained simply in terms of anomalous reflection of external...

Energy efficiency of electrical infrared heating elements

A measurement system has been designed to characterize the radiant energy efficiency of infrared heating elements. The system also allows for measurement of the radiant heat flux distribution emitted from radiant heater assemblies. To facilitate these, a 6-axis robotic arm is fitted with a Schmidt–Boelter radiant heat flux gauge. A LabVIEW interface operates the robot and positions the sensor in the desired location and subsequently acquires the desired radiant heat flux measurement. To illustrate the functionality of the measurement system and methodology, radiant heat flux distributions and efficiency calculations are performed for a commercially available ceramic heater element for two cases. In the first, a spherical surface is traced around the entire heater assembly and the total radiant power and net radiant efficiency is computed. In the second, 50cm×50cm vertical planes are traced parallel to the front face of the heater assembly at distances between 10cm and 50cm and the in-plane power and efficiencies are computed. The results indicate that the radiant efficiencies are strongly dependant on the input power to the element and, for the in-plane efficiencies, depend on the distance from the heater.

Karpman-Washimi magnetization with electron-exchange effects in quantum plasmas

The influence of quantum electron-exchange on the Karpman-Washimi ponderomotive magnetization is investigated in quantum plasmas. The ponderomotive magnetization and the total radiation power due to the non-stationary Karpman-Washimi interaction related to the time-varying field intensity are obtained as functions of the de Broglie wave length, Debye length, and electron-exchange parameter. The result shows that the electron-exchange effect enhances the cyclotron frequency due to the ponderomotive interactions in quantum plasmas. It is also shown that the electron-exchange effect on the Karpman-Washimi magnetization increases with increasing wave number. In addition, the Karpman-Washimi magnetization and the total radiation power increase with an increase in the ratio of the Debye length to the de Broglie wave length. In streaming quantum plasmas, it is shown that the electron-exchange effect enhances the ponderomotive magnetization below the resonant wave number and, however, suppresses the ponderomotive magnetization above the resonant wave number. The variation of the Karpman-Washimi magnetization and the radiation power due to the variation of the electron-exchange effect and plasma parameters is also discussed.

On the radiative and thermodynamic properties of the cosmic radiations using COBE FIRAS instrument data: III. Galactic far-infrared radiation

Using the three-component spectral model describing the FIRAS average continuum spectra, the exact analytical expressions for thermodynamic and radiative functions of Galactic far-infrared radiation are obtained. The COBE FIRAS instrument data in the 0.15–2.88 THz frequency interval at the mean temperatures of T1 = 17.72 K, T2 = 14 K and T3 = 6.73 K are used for calculating the radiative and thermodynamic functions, such as the total radiation power per unit area, total energy density, total emissivity, number density of photons, Helmholtz free energy density, entropy density, heat capacity at constant volume and pressure for the warm, intermediate-temperature and very cold components of the Galactic continuum spectra. The generalized Stefan-Boltzmann law for warm, intermediate-temperature and very cold components is constructed. The temperature dependence of each component is determined by the formula IS–B(T) = σ′T6. This result is important when we construct the cosmological models of radiative transfer that can be applied inside the Galaxy. Within the framework of the three-component spectral model, the total number of photons in our Galaxy and the total radiation power (total luminosity) emitted from a surface of the Galaxy are calculated. Their values are NGtotal = 1.3780 × 1068 and IGtotal(T) = 1.0482 × 1036 W. Other radiative and thermodynamic properties of the Galactic far-infrared radiation (photon gas) of the Galaxy are calculated. The expressions for astrophysical parameters, such as the entropy density/Boltzmann constant and number density of the Galactic far-infrared photons are obtained. We assume that the obtained analytical expressions for thermodynamic and radiative functions may be useful for describing the continuum spectra of the far-infrared radiation for other galaxies.

Radiation-Pattern-Reconfigurable Antenna Using Monopole-Loop for Fitbit Flex Wristband

This letter presents a radiation-pattern-reconfigurable antenna for a Fitbit Flex wristband, which provides health information about the human body. The advantages of this antenna are improvements in antenna performance and controlling beam directions compared to the existing antenna for the Fitbit Flex. We proposed the placement of an antenna on the upper side of the Fitbit Flex wristband as a monopole antenna. We compared the existing Fitbit Flex antenna to the proposed antennas by several antenna performance factors. Total radiation power (TRP) and total isotropic sensitivity (TIS) are measured, and the specific absorption rate (SAR) result is simulated. The proposed antennas show improvement in performance when compared to the existing Fitbit Flex existing antenna.

On the radiative and thermodynamic properties of the cosmic radiations using COBE FIRAS instrument data: I. Cosmic microwave background radiation

Using the explicit form of the functions to describe the monopole and dipole spectra of the Cosmic Microwave Background (CMB) radiation, the exact expressions for the temperature dependences of the radiative and thermodynamic functions, such as the total radiation power per unit area, total energy density, number density of photons, Helmholtz free energy density, entropy density, heat capacity at constant volume, and pressure in the finite range of frequencies v1≤v≤v2 are obtained. Since the dependence of temperature upon the redshift z is known, the obtained expressions can be simply presented in z representation. Utilizing experimental data for the monopole and dipole spectra measured by the COBE FIRAS instrument in the 60–600 GHz frequency interval at the temperature T=2.72548 K, the values of the radiative and thermodynamic functions, as well as the radiation density constant a and the Stefan-Boltzmann constant σ are calculated. In the case of the dipole spectrum, the constants a and σ, and the radiative and thermodynamic properties of the CMB radiation are obtained using the mean amplitude Tamp=3.358 mK. It is shown that the Doppler shift leads to a renormalization of the radiation density constant a, the Stefan-Boltzmann constant σ, and the corresponding constants for the thermodynamic functions. The expressions for new astrophysical parameters, such as the entropy density/Boltzmann constant, and number density of CMB photons are obtained. The radiative and thermodynamic properties of the Cosmic Microwave Background radiation for the monopole and dipole spectra at redshift z≈1089 are calculated.

On the radiative and thermodynamic properties of the cosmic radiations using COBE FIRAS instrument data: II. Extragalactic far infrared background radiation

Using the three-component spectral model describing the FIRAS average continuum spectra, the analytical expressions for the temperature dependence of the thermodynamic and radiative functions of the galactic far-infrared radiation are obtained. The COBE FIRAS instrument data in the 0.15 - 2.88 THz frequency interval at the mean temperatures T = 17.72 K, T = 14 K, and T =6.73 K are used for calculating the radiative and thermodynamic functions, such as the total radiation power per unit area, total energy density, total emissivity, number density of photons, Helmholtz free energy density, entropy density, heat capacity at constant volume and pressure for the warm, intermediate-temperature and very cold components of the Galactic continuum spectra. The generalized Stefan-Boltzmann laws for the warm, intermediate-temperature and very cold components are constructed. This result is important when we construct the cosmological models of radiative transfer in the inner Galaxy. Within the framework of the three- component spectral model, the total number of photons in our Galaxy and the total radiation power (total luminosity) emitted from the surface of the Galaxy are calculated. Other radiative and thermodynamic properties of the galactic far-infrared radiation (photon gas) for the Galaxy are presented. The expressions for astrophysical parameters, such as the entropy density/Boltzmann constant, and number density of the galactic far-infrared photons are obtained. We assume that the obtained analytical expressions for thermodynamic and radiative functions may be useful for describing the continuum spectra of the far-infrared radiation for outer galaxies.

The accretion–ejection coupling in the black hole candidate X-ray binary MAXI J1836−194

We present the results of our quasi-simultaneous radio, sub-mm, infrared, optical and X-ray study of the Galactic black hole candidate X-ray binary MAXI J1836-194 during its 2011 outburst. We consider the full multi-wavelength spectral evolution of the outburst, investigating whether the evolution of the jet spectral break (the transition between optically-thick and optically-thin synchrotron emission) is caused by any specific properties of the accretion flow. Our observations show that the break does not scale with the X-ray luminosity or with the inner radius of the accretion disk, and is instead likely to be set by much more complex processes. We find that the radius of the acceleration zone at the base of the jet decreases from ~10$^6$ gravitational radii during the hard intermediate state to ~10$^3$ gravitational radii as the outburst fades (assuming a black hole mass of 8 M$_{\odot}$), demonstrating that the electrons are accelerated on much larger scales than the radius of the inner accretion disk and that the jet properties change significantly during outburst. From our broadband modelling and high-resolution optical spectra, we argue that early in the outburst, the high-energy synchrotron cooling break was located in the optical band, between $\approx 3.2 \times 10^{14}$ Hz and $4.5 \times 10^{14}$ Hz. We calculate that the jet has a total radiative power of $\approx 3.1 \times 10^{36}$ ergs s$^{-1}$, which is ~6% of the bolometric radiative luminosity at this time. We discuss how this cooling break may evolve during the outburst, and how that evolution dictates the total jet radiative power. Assuming the source is a stellar-mass black hole with canonical state transitions, from the measured flux and peak temperature of the disk component we constrain the source distance to be 4-10 kpc.

Preparation and performance evaluation of Er2O3 coating-type selective emitter

An Er2O3 coating-type selective emitter for themophotovoltaic application was prepared by plasma spray technology. The test results show that plasma spray technology could be used to prepare the Er2O3 coating-type selective emitter with good stability at 1400°C. Based on the measurements of the high temperature normal spectral emissivity and the spectral hemispherical emissivity of the samples at room temperature, the influence of the coating thickness was discussed, and the selective emission performance of the sample was evaluated using radiative efficiency as the criterion. The results demonstrate that the emission of substrate could not be neglected unless the coating thickness would be larger than the penetration depth, which is around 100 μm. The selective emission peak of the Er2O3 coating occurs at 1550 nm, matching well with the GaSb cells. However, the radiative efficiency is not larger than that of the SiC emitter, because the non-convertible emission of 1.725–5 μm accounts for a large proportion of the total radiation power, especially at high temperature. Effective suppression of this band emission is essential to the improvement of the radiation efficiency of the emitter.

Overlapped optics induced perfect coherent effects

For traditional coherent effects, two separated identical point sources can be interfered with each other only when the optical path difference is integer number of wavelengths, leading to alternate dark and bright fringes for different optical path difference. For hundreds of years, such a perfect coherent condition seems insurmountable. However, in this paper, based on transformation optics, two separated in-phase identical point sources can induce perfect interference with each other without satisfying the traditional coherent condition. This shifting illusion media is realized by inductor-capacitor transmission line network. Theoretical analysis, numerical simulations and experimental results are performed to confirm such a kind of perfect coherent effect and it is found that the total radiation power of multiple elements system can be greatly enhanced. Our investigation may be applicable to National Ignition Facility (NIF), Inertial Confined Fusion (ICF) of China, LED lighting technology, terahertz communication, and so on.

Radiation of de-excited electrons at large times in a strong electromagnetic plane wave

The late time asymptotics of the physical solutions to the Lorentz–Dirac equation in the electromagnetic external fields of simple configurations–the constant homogeneous field, the linearly polarized plane wave (in particular, the constant uniform crossed field), and the circularly polarized plane wave–are found. The solutions to the Landau–Lifshitz equation for the external electromagnetic fields admitting a two-parametric symmetry group, which include as a particular case the above mentioned field configurations, are obtained. Some general properties of the total radiation power of a charged particle are established. In particular, for a circularly polarized wave and constant uniform crossed fields, the total radiation power in the asymptotic regime is independent of the charge and the external field strength, when expressed in terms of the proper-time, and equals a half the rest energy of a charged particle divided by its proper-time. The spectral densities of the radiation power formed on the late time asymptotics are derived for a charged particle moving in the external electromagnetic fields of the simple configurations pointed above. This provides a simple method to verify experimentally that the charged particle has reached the asymptotic regime.

New results in fundamental theory of synchrotron radiation

Examining the characteristics of radiation from scalar particles in second excited state, which could be regarded at as a three-level system, we deliver (and solve) the problem on spectral properties in simplest form. Using the methods of quantum theory, we establish that partial contribution of fixed harmonic to the total power of radiation does not vanish in ultrarelativistic domain, and this fact contradicts the results known in classical approach. We also consider the evolution of radiation maximum. In particular, for a scalar particle we find the condition for radiation maximum to stay at highest possible harmonic.

Generalized Wien’s Displacement Law in Determining the True Temperature of $$\text{ ZrB }_{2}$$ ZrB 2 –SiC-Based Ultrahigh-Temperature Ceramic: Thermodynamics of Thermal Radiation

The temperature dependence of the generalized Wien displacement law is investigated. For determining the true temperature of a \(\text{ ZrB }_{2}\)–SiC-based ultrahigh-temperature ceramic, the experimental values of the position of the maximum of the spectral density power are needed. Thermodynamics of the thermal radiation of \(\text{ ZrB }_{2}\)–SiC is constructed by using the temperature dependence of the generalized Stefan–Boltzmann law. The calculated values of the normal total emissivity for \(\text{ ZrB }_{2}\)–SiC at different temperatures are in good agreement with experimental data. The total radiation power emitted from a surface of \(\text{ ZrB }_{2}\)–SiC specimens at different temperatures is calculated. The temperature dependences of the Helmholtz free energy, entropy, heat capacity at constant volume, pressure, enthalpy, and internal energy of the thermal radiation of \(\text{ ZrB }_{2}\)–SiC are obtained. For determining the true temperature, experimental values of either the normal total emissivity or the normal total energy density are needed. The uncertainty in the determination of the true temperature is no greater than 1 %. A new universality class of bodies with a new relationship between the temperature \(T\) and the position of the spectral energy density maximum is established.

Contribution of Ne ions to radiation enhancement in JT-60U divertor plasmas

The emission spectra from Ne seeded divertor plasmas of JT-60U are measured by an absolutely calibrated vacuum ultraviolet spectrometer and analyzed with a collisional–radiative model. The radiative power of Ne ions from the inner divertor plasma in the detached phase contributes 55% of the total radiative power while that in the attached phase contributes 34% even at a similar Ne seeding rate. From an analysis of the intensity ratios of Ne VIII spectral lines, it is found that volume recombination of Ne IX to Ne VIII occurs more frequently in the detached plasma, enhancing Ne VIII density. This is one of the leading processes that enhances the radiative power from highly charged Ne ions in the detached plasma.

High-precision method for determining the position of laser beam focal plane∗∗Reported at the ‘Laser Optics’ Conference (St. Petersburg, Russia, June 2012).

The method of wavefront doubled-frequency spherical modulation for determining the laser beam waist position has been simulated and experimentally studied. The error in determining the focal plane position is less than . The amplitude of the control doubled-frequency electric signal is experimentally found to correspond to 12 % of the total radiation power.

Design and fabrication of a multi-purpose soft x-ray array diagnostic system for KSTAR

A multi-purpose soft x-ray array diagnostic system was developed for measuring two-dimensional x-ray emissivity profile, electron temperature, Ar impurity transport, and total radiation power. A remotely controlled filter wheel was designed with three different choices of filters. The electron temperature profile can be determined from the ratio of two channels having different thickness of Be layer, and the Ar impurity concentration transport can be determined from a pair of Ar Ross filters (CaF(2) and NaCl thin films). Without any filters, this diagnostic system can also be used as a bolometer.