Emission Power Research Articles

Fisher information and the Cramér-Rao lower bound in single-pixel localization microscopy with spatiotemporally modulated illumination.

Single-pixel imaging, the concept that an image can be captured via a single-pixel detector, is a cost-effective yet powerful technique to reduce data acquisition duration without sacrificing image resolution when properly structured illumination patterns are introduced. Normally, the image reconstruction process is subject to the diffraction limit. Here, we study the possibility of exploiting the information contained in the illumination patterns to enable a form of single-pixel localization microscopy (SPLM) for super-resolution. This concept is inspired by coherent holographic image reconstruction by phase transfer (CHIRPT) microscopy. CHIRPT microscopy is a single-pixel imaging technique that uses structured illumination that is spatiotemporally modulated (STM) so that a unique temporal modulation pattern is imparted to each point within a large illumination volume. The fluorescent light emitted by molecules contains the same temporal modulations as the illumination patterns at the locations of the molecules. By recording a portion of the total emitted fluorescent power, the signal may be numerically processed to form an image. Unique temporal modulation patterns that excite fluorescent probes at each point can also be used to localize individual molecules by matching their particular temporal light emission patterns to the measured temporal signal. This paper evaluates the feasibility of SPLM with STM illuminations used in and inspired by CHIRPT microscopy via the information content its data carry about the emitter location(s). More specifically, we provide the mathematical formalism of Fisher information (FI) and the Cramér-Rao lower bound (CRLB) associated with the location parameters of the emitter(s). The FI and CRLB are then numerically evaluated under different experimental assumptions to assess the effects of experimental parameters on localization precision. Last, we compare the single-pixel CRLB to that from camera-based single-molecule localization microscopy in the localization of a single emitter. We show that SPLM has several distinguishing characteristics that provide certain advantages, such as relatively constant CRLB over a very large illumination volume and improved CRLB for 3D localization due to the information coupling introduced by simultaneous modulations of the transverse axes.

The resistance of leds to the effects of gamma radiation in various operating modes

The effect of active and passive power modes on the resistance of the LEDs (LEDs) made of multilayer AlGaAs heterostructures to gamma-quantum irradiation was studied. Three characteristic stages of emission power reduction during irradiation are distinguished for the studied LEDs irrespective of the power supply mode. When irradiating LEDs in the active power supply mode, two differently directed processes of changes in the emission power are observed. The assumption is made that the first process is caused by a decrease in the LED emission power due to the injection of appropriate radiation defects. The second process is caused by a partial recovery of the emission power due to radiation, radiation-thermal, and/or electrostimulated annealing of some of the defects created. The observed recovery of the emission power in the active power mode of the LED during irradiation significantly increases its resistance to gamma-ray irradiation.

An experimental study of spectral radiative properties of multi-walled carbon nanotube coating for heat dissipation

Thermal management serves a crucial role in the stable operation of electronic equipment due to its miniaturization and functionality. Enhancing radiation heat transfer through heat dissipation coating is an effective method to improve the heat dissipation performance of electronic devices in thermal management of narrow space. In this paper, we employed the high emissivity property of multi-walled carbon nanotubes to improve the radiative heat dissipation performance of the coating. The effect of the distribution of multi-walled carbon nanotubes on the emissivity of the coating was studied with the finite-difference time-domain method. The emissivity of the coating with random distribution of multi-walled carbon nanotubes was found to be greater than that of the coating with vertical distribution of multi-walled carbon nanotubes. In order to further investigate the radiative properties of randomly distributed multi-walled carbon nanotube coatings, we experimentally investigated the effect of coating thickness and multi-walled carbon nanotube mass fraction on the spectral radiative properties of the coatings. We obtained the relationships between coating thickness, carbon nanotube mass fraction and coating radiation power. The data can provide some guidance for the regulation of radiation power of heat dissipation coatings and the selection of common coating processes. The maximum average emissivity and radiation power of the multi-walled carbon nanotube coating is 0.97, and 491.6 W m−2, respectively.

Проблемы измерения потоков энергии излучения на объектах транспортной инфраструктуры с излучающей плазмой

Purpose: Transport infrastructure objects comprise numerous technical devices containing radiating plasma. They include visible and spectral radiation sources, switching devices at traction substations, high-temperature heat exchangers and combustion chambers. During experimental study of such devices, the measurements of power and spectral composition of radiation emitted by plasma are carried out. For this, as a rule, photodiodes of small sizes are used, installed at a certain distance from plasma formation. The purpose of the present work is to establish relationship between plasma emission power and radiation flux amount incident on photodiode working surface. Methods: To solve the set task, the method of direct integration of radiation transfer equation in homogeneous plasma structure assumption, but in the absence of local thermodynamic equilibrium presence assumption, is used. The cases of reflecting and absorbing surfaces, limiting a plasma, are considered. Results: Explicit expressions are found for radiation flux which exits plasma formation surface and for flux incident on photodiode surface. The dependence for the ratio of the values of these radiation fluxes to plasma geometric sizes and optical thickness is numerically studied. For the case of reflecting surfaces that bound plasma, simple asymptotic expression is found for ratio value for the fluxes and applicability field of the expression is determined. Practical significance: The ratios, which establish relationship between plasma radiation power and power value for radiation flux incident on photodiode working surface, make it possible to solve the main task of the experimental study of plasma formations — the restoration of plasma characteristics according to photocurrent measurement results. Obtained in the work results can be used at experimental study of technical devices containing emitting plasma.

Hollow vortices of neutrino from Kerr black hole

In the present paper, a novel family of neutrino fields with a hollow distribution outside a rotating black hole is developed. To analyze the hollow neutrino field which excited from the Kerr black hole a theoretical method is proposed. The neutrinos wave function from the Kerr black hole is reported as hypergeometric form. Similar to the hollow in the core of the rotating black hole, the emitted neutrinos with a dark core are reported. The emitted neutrino beams are characterized by a tube of energy and angular momentum with a singularity at the center. The tubes have a symmetric axis that coincided with the symmetric axis of the rotating black hole. The number rate, emitted power, and angular momentum of the neutrinos near the rotation axis of the black hole vanish. Furthermore, the maximum rate is taken place near the equator plane of the black hole. As the black hole is rotating, its angular momentum is transferred to the emitted neutrinos, hence the helicity of the neutrinos wave function is excited.

Wear Comfort Characteristics of Al2O3/ATO/TiO2-Embedded Multi-Functional PET Fabrics.

The wear comfort of Al2O3/ATO (antimony tin oxide, Sb2SnO5)/TiO2-embedded fabrics was examined in terms of the heat shielding property of ATO particles and emissivity of far-infrared (FIR) radiation according to the sheath/core ratio (wt. %) of Al2O3 and ATO particles embedded in the sheath/core yarns. The thermal radiation of the low-core-ratio (50 wt. %) Al2O3/ATO-embedded fabric was greater than that of the high-core-ratio (70 wt. %) Al2O3/ATO-embedded fabric, which was verified by the higher FIR emissivity. The heat-shielding effect of the ATO particles in the highly Al2O3/ATO-embedded yarns enabled it to shield the FIR emitted from sunlight, resulting in lower emissivity and emissive power of the highly embedded Al2O3/ATO yarn than lower embedded yarn. Accordingly, lower Al2O3/ATO-embedded yarns are required to obtain excellent thermal radiation of the fabrics. The fabric with a low core ratio (50 wt. %) exhibited superior moisture absorption, fast-drying properties, and a higher heat retention rate than fabrics with a high core ratio (70 wt. %). Furthermore, the fabric with a low core ratio exhibited superior breathability to the fabric with a high core ratio, resulting in easy moisture vapor permeability. These findings show that the fabric with a low core ratio (50%) of Al2O3/ATO particles imparts superior absorption, moisture vapor permeability, and thermal wear comfort to the high-core-ratio fabric (70%), giving it a comfortable wear-comfort feel while wearing the clothing. Hence, low-core-ratio yarn is suitable for warm-up fabric with UV-protection and anti-static characteristics.

Coherent amplification of radiation from two phase-locked Josephson junction arrays.

We analyze experimentally and theoretically mutual phase locking and electromagnetic interaction between two linear arrays with a large number of Josephson junctions. Arrays with different separation, either on the same chip or on two separate substrates are studied. We observe a large coherent gain, up to a factor of three, of emitted power from two simultaneously biased arrays, compared to the sum of powers from two individually biased arrays. The phenomenon is attributed to the phase locking of junctions in different arrays via a common electromagnetic field. Remarkably, the gain can exceed the factor of two expected for a simple constructive interference of two oscillators. The larger gain is explained by an additional consequence of mutual interaction between two large arrays. Mutual phase locking of large arrays does not only result in constructive interference outside the arrays, but also improved synchronization of junctions inside each array. Our conclusion is supported by numerical modelling.

THz Radiation Efficiency Enhancement from Metal-ITO Nonlinear Metasurfaces.

Strong single-cycle THz emission has been demonstrated from nonlinear plasmonic metasurfaces, when excited by femtosecond laser pulses. In order to invoke a higher nonlinear response, such metasurfaces have been coupled to thin indium-tin-oxide (ITO) films, which exhibit an epsilon-near zero (ENZ) behavior in the excitation wavelength range and enhance the nonlinear conversion. However, the THz conductivity of the ITO film also reduces the radiation efficiency of the meta-atoms constituting the metasurface. To overcome this, we etch the ITO layer around the plasmonic meta-atoms, which allows harnessing of the enhanced localized fields due to the ENZ behavior of the remaining ITO film, while improving the THz radiation efficiency. We report an increase of more than 1 order of magnitude in the emitted THz spectral power density, while the energy conversion efficiency approaches 10-6. This simple yet very effective fabrication scheme provides important progress toward increasing the range of applications of nonlinear plasmonic metasurface THz emitters.

Can third-party market cooperation solve the dilemma of emissions reduction? A case study of energy investment project conflict analysis in the context of carbon neutrality

The conflict mechanism of transnational energy investment projects is complex. The current study uses the enhanced graphic model for conflict resolution to build a four-pole game model to discuss the conflict resolution mechanism of energy investment projects. The results depicted that the host country's dilemma of carbon emission reduction and power supply cannot be solved only by unilateral efforts. All parties adopt the game's best strategy (cooperation, cooperation, promotion, support). The project's main investor provides energy that meets the environmental protection requirements. Technology investor provides new technologies for energy conservation and emission reduction. Enterprises of the host country improve various basic measures for carbon emission reduction. Environmental protection organizations and the public support the project and participate in carbon emission supervision. The implementation of energy emission reduction requires the effective participation of social groups, and the participation and supervision of environmental protection organizations and the public are conducive to promoting various stakeholders to achieve a balanced strategy for energy emission reduction. The results provide valuable policy implications for investment decision-makers and an important reference value for third-party market cooperation to solve the dilemma of energy emission reduction.

Pressurised Chemical Looping Combustion (PCLC): Air Reactor design

Bioenergy combustion with Carbon Capture and Storage (BECCS) is a key technology to achieve carbon negative emissions power generation. This can be achieved by coupling the biofuels combustion with CO2 capture and storage (CCS). The lowest cost for CCS corresponds at the moment to the Chemical Looping Combustion (CLC) process. This can use biofuels which can be gaseous (biomethane, biogas or syngas etc.), liquid (biodiesel, bioethanol, biobutanol and pyrolysis oils etc.) or solids (wood dust, charcoal dust, wood chips, wood pellets etc.) While plant design with gaseous and liquid biofuels would be simpler, plants using solid biofuels and based on two couple fluidisd beds would need the use of a third reactor named carbon stripper. In the specific case if we plan to couple a CLC plant with a turbo expander (to achieve the high efficiencies of a combined cycle power plant) we have to work with pressurized reactors. However, there are some technical barriers to the coupling of a chemical looping combustor with a turbo expander, such as: the operation of the combustor in pressurised conditions; the inventory balance among reactors; elutriated particles reaching the turbo expander. This explaind why there is no commercial plant at the moment capable to do this. The aim of this paper is to present a model for the dimensioning of an air reactor to be coupled to a turbo expander of the power of about 12 MWe. Based on this, the air mass flow can be obtained and the geometric parameters can be calculated, to have an air velocity which is needed to achieve the fast fluidization regime and to ensure a high conversion rate as well as particles and heat exchage among air and fuel reactor.

Comparative analysis of life cycle greenhouse gas emission of passenger cars: A case study in China

Greenhouse gas emission is a vital problem affecting the fate of mankind. To reduce the emission, passenger cars with various types of power system has been introduced in China. However, there is an uncertainty that whether these vehicles can reduce greenhouse gas emissions and how much emissions can be reduced, especially in terms of life cycle aspect. In this paper, a calculation method has been established to study their life cycle carbon emissions, with consideration of various power system, model class and electric driving range. It is found that most NEVs and Hybrid Electric Vehicle (HEVs) have emission reduction effects compared to internal combustion engine vehicles (ICEVs). The emission reduction rate of vehicles is between 6.56% and 44.4% in 2020, 13.97%–53.39% in 2025 and 19.65%–57.49% in 2030. It is also found that this reduction rate is significantly different between different vehicle class, power system and electric driving range. Battery electrical vehicle (BEVs) in 2020 with electric driving range over 700 km are even worse in carbon emission, the worst is −33.08%. The results could be useful for GHG emission prediction and power system selection for companies. Policies can be formulated to guide enterprise choosing power system with lower carbon emission.

Wavelength modulated diode probe laser for an interferometric cavity-assisted photothermal spectroscopy gas sensor

We report on key developments made in advancing Interferometric Cavity-Assisted Photothermal Spectroscopy (ICAPS) toward a method for rugged and cost-effective gas sensing. In ICAPS, a Fabry Perot Interferometer (FPI) is employed to transduce absorption induced and analyte specific refractive index changes occurring inside the interferometer. Periodic analyte excitation is achieved by modulation of the excitation laser’s wavelength and the photothermal signal is detected by measuring the intensity of the probe laser reflected by the FPI. Maximum sensitivity is achieved when the probe’s wavelength matches the inflection point of the FPI’s transfer function. We describe the development of a locking scheme based on current induced wavelength modulation of a cost-effective diode probe laser to keep its wavelengths at the inflection point of the FPI. Because of the diode lasers characteristics, this locking procedure causes changes in the emitted laser power, which in turn influences the sensor’s sensitivity. Therefore, a normalization procedure had to be developed to correct for this inherent probe power dependency of the ICAPS sensor’s sensitivity. First, a theoretical analysis of the photothermal signal generation is given. Then a strategy is presented for stable operation of the ICAPS sensor with constant sensitivity while actively locking the probe’s wavelength. Experimental results on the example of NO detection in N2 employing a quantum cascade laser (30 mW) emitting at 1900 cm−1 (LOD 2 ppm, NNEA of 3.3⋅10−6 W cm−1Hz−1⁄2) corroborate the validity of the developed theoretical model and demonstrate its applicability to achieve constant sensor sensitivity at different sensor set-points.

Ultimate stability of active optical frequency standards

Active optical frequency standards provide interesting alternatives to their passive counterparts. Particularly, such a clock alone continuously generates highly-stable narrow-line laser radiation. Thus a local oscillator is not required to keep the optical phase during a dead time between interrogations as in passive clocks, but only to boost the active clock's low output power to practically usable levels with the current state of technology. Here we investigate the spectral properties and the stability of active clocks, including homogeneous and inhomogeneous broadening effects. We find that for short averaging times the stability is limited by photon shot noise from the limited emitted laser power and at long averaging times by phase diffusion of the laser output. Operational parameters for best long-term stability were identified. Using realistic numbers for an active clock with $^{87}$Sr we find that an optimized stability of $\sigma_y(\tau) \approx 4\times10^{-18}/\sqrt{\tau [\mathrm{s}]}$ is achievable.

Transient Flashes in Saturn’s UV Aurora: An Analysis of Hubble Space Telescope 2013–2017 Campaigns and Cassini Magnetic Field Measurements

We examined Hubble Space Telescope images of Saturn’s northern UV aurora in 2013–2017, identified 29 short-lived flashes, and examined simultaneous magnetometer data collected by the Cassini orbiter. When observation cadence permitted, a flash lifetime of 4–17 min (subject to exposure time-related uncertainties), and a 40–70 min recurrence period were found. An occurrence map shows a strong preference in both local time (14–19 LT) and latitude (75–85°). These transient flashes are identified in both the presence and absence of Saturn’s main auroral oval, indicating the lack of dependence on the main emission power. The concurrent magnetic field pulsations generally form a sawtooth shape, and the local field strength experiences a change of 0.2 to 2.0 nT (depending on the distance of Cassini). The quasiperiodic pulsation events were all detected when the spacecraft was in the southern hemisphere with conjugate flashes in northern aurora, suggesting these events occur on closed field lines, and typically showing a sudden transition to a less lagging, more southward magnetic field configuration. We also found the ionospheric footprint of the spacecraft must be close to the region of flashes for magnetic field pulsations to be detected, implying a localised rather than global driving process.

Addendum to “Radiation emitted by a source orbiting a Schwarzschild–anti–de Sitter black hole”

In [J. P. B. Brito et al., Phys. Rev. D 104, 124085 (2021).], we studied the scalar radiation emitted by a source orbiting a Schwarzschild--anti--de Sitter black hole along circular geodesics. We presented results for the emitted power in the context of quantum field theory in curved spacetimes. We computed the emitted power for a region of the parameter space corresponding to large black holes when compared to the anti--de Sitter radius. In this addendum we investigate the regime of small black holes, i.e., the regime of ${M}^{2}\mathrm{\ensuremath{\Lambda}}\ensuremath{\lesssim}0$. In this regime, the emitted power, as a function of the source's angular velocity, exhibits resonant peaks associated with quasinormal frequencies.

A Multifunctional Flexible Electronic Skin for Dynamic Thermal Radiation Regulation and Electromagnetic Interference Shielding.

A multifunctional electronic skin with thermal radiation regulation and electromagnetic interference (EMI) shielding is urgent for electronic systems because of the thermal radiation emission and electromagnetic wave pollution. Herein, a flexible electronic skin was designed and fabricated, where the polyaniline (PANI) served as the functional layer and Ti3C2Tx MXene was employed as the conductive electrode. The transformation of emeraldine salt (ES) and leucoemeraldine base (LB) of PANI makes the skin achieve an infrared emissivity modulation, and the electromagnetic loss of PANI and ultrahigh electrical conductivity of Ti3C2Tx MXene make it exhibit EMI shielding ability. Benefiting from the special structural design, the multifunctional skin with a small thickness (0.3 mm) and low surface density (0.06 g/cm2) exhibits an excellent infrared emissivity modulation ability (Δε) of 0.32 with emissive power of 119.1 W/m2 at the wavelength range of 2.5-25 μm and total shielding effectiveness (SET) of 36.3 dB over the X-band (8.2-12.4 GHz). Meanwhile, the multifunctional skin remains black in the visible spectrum but a changeable color in the infrared spectrum. Even after repeated bending and twisting, the multifunctional skin still maintains a good emissivity adjustment. The simultaneous realization of dynamic thermal radiation regulation and EMI shielding endows the skin promising potential for various fields, such as adaptive infrared camouflage, thermal regulation, anticounterfeiting, and EMI shielding-related crossing field.

Radiation from axion star-neutron star binaries with a tilted rotation axis in the presence of plasma

We investigate the form of the radiation emitted by an axion star-neutron star binary using a f(r) = sech(r/R) profile for the axion star. Our analysis takes into account the co-rotating plasma of the neutron star. We find that there is significant enhancement to the radiated power if the neutron star’s spin is tilted towards the plane of the axion star-neutron star orbit, compared to the case where it is perpendicular. We also examine whether the neutron star’s co-rotating plasma can play a role in the emitted power and we find that even though dilute axion stars can in principle radiate more efficiently than dense axion stars, they will be pulled apart by the tidal forces of the neutron star.

Optical Epidermal Mimicry from Ultraviolet to Infrared Wavelengths.

Optical tissue phantoms present substantial value for medical imaging and therapeutic applications. We have developed an epidermal tissue phantom to mimic the optical properties of human skin from the ultraviolet to the infrared region, exceeding the breadth of existing studies. An epoxy matrix is combined with melanin-mimicking polydopamine via a cost-effective fabrication strategy. Reflectance and transmittance measurements enable calculation of the wavelength-dependent complex refractive index and absorption coefficient. Results are compared with literature data to establish agreement with a real human epidermis. By analyzing emissive power at a typical skin temperature, the epidermal tissue phantom is shown to accurately mimic the radiative properties of human skin. This simple, multifunctional material represents a promising substitute for human tissue for a variety of medical and bioengineering applications.

The Effect of Multi-Walled Carbon Nanotubes on the Heat-Release Properties of Elastic Nanocomposites

Of great importance in materials science is the design of effective functional materials that can be used in various technological fields. Nanomodified materials, which have fundamentally new properties and provide previously unrealized properties, have acquired particular importance. When creating heating elements and materials for deformation measurement, it is necessary to understand the patterns of heat release under conditions of mechanical deformation of the material, as this expands the potential applications of such materials. A study of elastomers modified with multi-walled carbon nanotubes (MWCNTs) has been carried at the MWCNTs concentration of 1–8 wt.%. The modes of heat release of nanomodified elastomers at a voltage of 50 V at different levels of tension are reported. The increment of the MWCNTs concentration to 7 wt.% leads to an increment in the power of heat emissions. It is worth noting the possibility of using the obtained elastomer samples with MNT as sensitive elements of strain sensors, which will allow obtaining information about physical and chemical parameters following the principles of measuring the change in electrical resistance that occurs during stretching and torsion. The changes in conductivity and heat emission under different conditions have been studied in parallel with Raman mapping and infrared thermography. The reported studies allow to make the next step to develop flexible functional materials for the field of electric heating and deformation measurement based on elastic matrices and nanoscale conductive fillers.

Estimation of Traffic Influence on Energy Saving at GSM Channels with Reallocation

This paper presents an innovative procedure for base station emission power calculation in the case of traffic channels reallocation implementation in GSM mobile systems. The main idea of active traffic channels reallocation is to place the connections which require higher emission power due to higher mutual distance between base station and mobile station to the first frequency carrier because these channels have to be always in active mode due to the applied discipline of traffic service in GSM mobile systems. The principle of connections reallocation on the base of distance values sequence determination is novelty comparing to the much more applied principle of connections arrangement according to the propagation conditions. Power saving as the result of this method usage is compared to the necessary power when the sequential hunting with homing method of idle channel looking for is applied. Two special cases are analyzed: 1. the case of low offered traffic (when not more than 6 traffic channels are busy on average) and the case when offered traffic is increased. It is proved that the achieved relative energy saving when the offered traffic is increased over 6Erl rapidly grows at first and then begins to fall. It is important that the absolute value of power saving continuously increases when the offered traffic is increased. One typical example of base station emission power save daily profile is presented on the base of the obtained results.