On physical investigation of ball lightnings

Explanations for the long lifetime of spherically symmetric objects in nature and the short lifetime of laboratory plasma are given. A qualitative description of the relativistic model of ball lightning is also given, which is a spherical electric region with strong electric and magnetic fields. The plasma temperature in the zone of the ball-lightning generation is measured by the spectroscopic method. A large ball lightning, the maximum diameter of which is equal to one meter and which stands in the region of its generation, is also registered after the formation and departure of a high-energy ball lightning. The reason for the low emissive power in the optical range characteristic for the atmospheric ball lightning is explained by the absence of electron transitions in the outer proton-containing shell. The absence of electrical breakdown at ultrahigh electric field between the core and the outer shell of the ball lightning and its destruction at the moment when the resulting force becomes nonzero are also explained.

The VIIRS-Based RST-FLARE Configuration: The Val d’Agri Oil Center Gas Flaring Investigation in Between 2015–2019

The RST (Robust Satellite Techniques)-FLARE algorithm is a satellite-based method using a multitemporal statistical analysis of nighttime infrared signals strictly related to industrial hotspots, such as gas flares. The algorithm was designed for both identifying and characterizing gas flares in terms of radiant/emissive power. The Val d’Agri Oil Center (COVA) is a gas and oil pre-treatment plant operating for about two decades within an anthropized area of Basilicata region (southern Italy) where it represents a significant potential source of social and environmental impacts. RST-FLARE, developed to study and monitor the gas flaring activity of this site by means of MODIS (Moderate Resolution Imaging Spectroradiometer) data, has exported VIIRS (Visible Infrared Imaging Radiometer Suite) records by exploiting the improved spatial and spectral properties offered by this sensor. In this paper, the VIIRS-based configuration of RST-FLARE is presented and its application on the recent (2015-2019) gas flaring activity at COVA is analyzed and discussed. Its performance in gas flaring characterization is in good agreement with VIIRS Nightfire outputs to which RST-FLARE seems to provide some add-ons. The great consistency of radiant heat estimates computed with both RST-FLARE developed configurations allows proposing a multi-sensor RST-FLARE strategy for a more accurate multi-year analysis of gas flaring.

Changing the Shape of Watt-Ampere Characteristic of LEDs Based upon GaP (λ = 590 nm) Irradiated by Gamma-Quanta

There are two distinctive regions can be identified (low (LC) and high currents (HC)) of a watt-ampere (W-I) characteristic of initial LEDs based upon GaP with 590 nm wavelength. The established patterns differ in the exponent. At the same time, the LC region corresponds to an increase in the efficiency of conversion of operating current into light radiation, and the HC region is a slow decline with an increase in the operating current. As a result of irradiation with gamma-quanta in the passive power mode, the change in the shape ofW-Icharacteristic is established, which can be characterized by an increase in the threshold current separating the LC and HC regions with an increase in the irradiation dose. The change in the emissive power of the LEDs and the shift of the threshold current occurs in two stages: in the first stage, the emissive power decreases due to radiation-stimulated rearrangement of the initial defect structure. At the same time, with an increase in the radiation dose, a partial recovery of the emissive power is observed against the background of its overall decrease. At the end of the first stage, the dependence of the damage coefficient on the operating current density in measurements of theW-Icharacteristics is manifested explicitly. The second stage of reducing the emissive power due to the introduction of radiation defects. In this case, the damage coefficient does not depend on the working current density, and the observed differences are due to the fact that by the end of the first stage its contribution to the overall reduction in emissive power is inversely proportional to the working current density. The established patterns can be used at the stage of designing the LEDs to substantiate the choice of the optimal value of the operating current density and to predict the resistance to irradiation with gamma rays.

Heat Storage and Release Characteristics of Ceramic-Imbedded Woven Fabric for Emotional Clothing

This study examined the heat storage and release characteristics of ZrC-imbedded woven fabrics by light emission and thermal manikin experiments. The surface temperature of the ZrC-imbedded fabric was higher than that of the regular PET fabric. Furthermore, the Clo values of both the total and torso of the ZrC-imbedded fabric by the thermal manikin experiment were higher than those of the regular PET fabric, which suggests that the heat release is caused by far infrared rays emitted from the ZrC particles imbedded in the yarns as they receive light. This was confirmed by the higher emissivity and emissive power of the ZrC-imbedded fabric. However, the tactile hand of the ZrC-imbedded fabric needs to be improved by adjusting the structural parameters of the fabric and finishing process factors.

Thermal Modeling of a Building Integrated Radiative Cooler for Space Cooling Applications

Recent developments of plasmonic emitters that emit infra-red radiation in the range of 8–13 micron wavelengths that can be transmitted through the atmosphere have opened up the potential of cooling buildings passively by radiating heat through this atmospheric window into the deep space. This paper presents an analysis of the potential of this method to cool buildings radiatively 24 hours per day. Air conditioning units consume a large amount of electricity and are the main drivers of peak electricity loads. A transient thermal model of a building integrated radiative cooling (BIRC) system was carried out for passive radiative cooling of buildings. A MATLAB code was developed for solving the heat transfer model of the BIRC system using a numerical iterative approach. The effects of operating parameters such as cooling emissive power and ambient conditions on the performance of the system were studied. Furthermore, effects of non-radiative heat transfer processes were studied by considering different heat transfer coefficients. Based on this analysis, energy savings potential of radiative cooling of buildings was estimated for the climatic conditions of Miami, FL, and Chicago, IL, USA for a fraction of a roof surface covered with a radiative cooler. Further, the results of this analysis are in line with previous studies estimating the cooling potential of up to 100 W/m2 with radiative cooling systems. These results will help in estimating the economic value of cooling buildings by using plasmonic emitting surfaces on the building skins.

An experimental study on thermal radiation of fire whirl

Fire whirl is frequently observed in wildland fires, and may cause serious difficulty in firefighting owing to its significant turbulent flow. In this paper, the radiation of fire whirl is investigated through experiments using a fire whirl facility made up of an air curtain apparatus, with five different sizes of n-heptane pools (25, 30, 35, 40 and 45 cm). The flame contour was extracted by image processing. By using infrared methods, the flame emissivity of fire whirl at different heights for different pool diameters was measured, and thereby a correlation was developed between the flame emissivity and the flame diameter. The soot volume fraction in the luminous flame is estimated to range within 2.5 × 10−6 to 4.0 × 10−6, much higher than that of general heptane pool fires, which provides an explanation of the higher flame emissivity of fire whirl. The emissive power profile v. normalised height is deduced from flame emissivity and flame temperature data. A multizone flame model (in which each zone is assumed as a grey body) is used, based on the measured data of flame emissivity, to predict the radiation of fire whirl. Comparison between the predicted and measured data of radiative flux shows good agreement.

РЕДОКС-ПОТЕНЦІАЛ ТА СТАН ПЕРЕКИСНОГО ОКИСНЕННЯ ЛІПІДІВ КРОВІ КОРІВ, ЩО УТРИМУЮТЬСЯ У ЕКОЛОГІЧНО НЕСПРИЯТЛИВИХ УМОВАХ

The paper highlights the investigations into the effects of the complex of unfavorable ecological factors which appear as a result of Chernobyl-derived contamination of farm lands on the intensity of peroxide oxidation of lipids and glutathione chain of the antioxidant system of dairy cows, as well as on the changes in the redox-potential of blood. The territory that suffered from Chernobyl-derived radionuclide contamination is characterized by the unfavorable ecological situation which is connected with the increase in the radioactive load on animals, as well as with the decrease in the part of soluble (exchange) form of biogenic mineral elements of soils. The above conditions make it possible to initiate a complex of biochemical changes caused by water radiolysis, by the increase in the active forms of oxygen and by the protection of the body from the products of peroxidation which appear as a result of the effects of radiolysis products. The investigation is aimed at determining the redox-potential of venous blood and separate indices of the peroxide oxidation of lipids and the antioxidant system of blood in cows kept in the zone which was contaminated by the man-caused radio nuclides , as compared with cows kept in the zone with background values of radioactivity and ᶨ- irradiation emissive power. The investigation results make it possible to establish that in the blood of cows kept under ecologically unfavorable conditions one can observe the increase in the concentration of the products of lipid peroxide oxidation: hydroperoxide lipids and malone dialdehyde. Under the above conditions one can establish the changes in the activity of the glutathione chain of the antioxidant system: the decrease in the part of renewed glutathione and the authentic increase in the part of oxidized glutathione and the decrease in the activity of glutathione reductase as compared with cows kept under ecologically favorable conditions. It has been established that under the effects of unfavorable ecological factors one can observe the increase in the positive redox-potential of blood which testifies to the disturbances between oxidized and renewed potentials.

Observations of energy transport and rate of spreads from low-intensity fires in longleaf pine habitat – RxCADRE 2012

Wildland fire rate of spread (ROS) and intensity are determined by the mode and magnitude of energy transport from the flames to the unburned fuels. Measurements of radiant and convective heating and cooling from experimental fires are reported here. Sensors were located nominally 0.5 m above ground level. Flame heights varied from 0.3 to 1.8 m and flaming zone depth varied from 0.3 to 3.0 m. Fire ROS derived from observations of fire transit time between sensors was 0.10 to 0.48 m s–1. ROS derived from ocular estimates reached 0.51 m s–1 for heading fire and 0.25 m s–1 for backing fire. Measurements of peak radiant and total energy incident on the sensors during flame presence reached 18.8 and 36.7 kW m–2 respectively. Peak air temperatures reached 1159°C. Calculated fire radiative energy varied from 7 to 162 kJ m–2 and fire total energy varied from 3 to 261 kJ m–2. Measurements of flame emissive power peaked at 95 kW m–2. Average horizontal air flow in the direction of flame spread immediately before, during, and shortly after the flame arrival reached 8.8 m s–1, with reverse drafts of 1.5 m s–1; vertical velocities varied from 9.9 m s–1 upward flow to 4.5 m s–1 downward flow. The observations from these fires contribute to the overall understanding of energy transport in wildland fires.