• NEANIAS Atmospheric Research Community

Measurements of photosynthetically active radiation (PAR) were taken using an Apogee SQ-110 sensor (Apogee Instruments, Inc., Logan, UT, USA). Measurements were taken at Cataract Scout Park, Appin, N.S.W. (34°14'42.29"S 150°49'24.97"E) as part of the Characterizing Organics and Aerosol Loading over Australia (COALA-2020) campaign. The sensor was placed on an exposed railing 4.35 m above ground level. Measurements were taken at 1 Hz resolution. The measurements reported here are 1-minute averages of 1 Hz measurements. Both PPFD (Photosynthetic Photon Flux Density, measured wavelength range 400-700 nm) and YPFD (Yield Photon Flux Density, measured wavelength range 360-760 nm) are reported. COALA-2020 was funded by Australia's National Environmental Science Program through the Clean Air and Urban Landscapes hub

The paper presents the results of analysis of measurement methods for radon flux density from the soil surface. A new method of monitoring of undisturbed radon flux density from the soil surface is described. It may be applied within a wide range of meteorological conditions. The method is based on registration of a-radiation of radon decay products collected inside an accumulation chamber installed on the soil surface. The accumulative chamber has some small vent holes for partial soil gas emission. The procedure of calibration and determination of correction coefficients is described. The results of testing of the method and comparison of the monitoring data obtained by different methods are discussed. The new method differs from the analogues in the way that it allows the authors to investigate diurnal variations of radon flux density.

This paper presents an evaluation method of for specific iron losses in non-oriented laminated steel suitable for electric motors and transformers in the case of a sinusoidal excitation. The model is based on the separation of loss contribution due to hysteresis, eddy currents and excess losses and it is proposing an identification procedure for the model coefficients from multi-frequency single sheet tests. The frequencies used are in the range 10 Hz and 150 Hz and with the values of magnetic flux density in the range 0.1 T and 1.4 T. The model was applied on six magnetic materials of different thicknesses (between 0.35 mm and 0.65 mm) and alloy compositions. Hysteresis and eddy currents loss coefficients have been considered as dependent on the frequency. For curve fitting of these coefficients third and fourth polynomials were employed, with good result for all the frequencies and magnetic flux density values specified above.

{"references": ["T. Nunn, \"A comparison of liquid-filled and dry-type transformer technologies\", IEEE IAS/PCA Cement Industry Technical Conference, pp. 105-112, 2000.", "John J. Winders, \"Power Transformers Principles and Applications\", Marker Dekker, Inc. New York, 2002.", "E. Rahimpour, D. Azizian, \"Analysis of temperature distribution in cast-resin dry-type transformers,\" Electrical Engineering, vol. 89, pp. 301-309, April 2006.", "P. K. Dooley, \"A comparison of liquid-filled and dry-type transformers for industrial applications\", Pulp and Paper Industry Technical Conference, 16-20 June, 1997.", "Cooper Power Systems, \"Application for LEED Innovation & Design Points, Transformer Technology: Liquid-filled vs. Dry-type\", Bulletin B210-05059, Revision 1, February 2008.", "Jehan Shazly, Amr A. Adly, \"Extension to the finite element technique for the magneto-thermal analysis of aged oil cooled-insulated power transformers\", pp. 167-176, April 2012.", "Marina A. Tsili, Eleftherios I. Amoiralis, Anthonios G. Kladas and Athanassios T. Souflairis, \"Power transformer thermal analysis by using an advanced coupled heat transfer and fluid flow FEM model\", International Journal of Thermal Sciences, vol. 53, pp. 188-201, 2012.", "Hua-Shu Liu, Lin Ma, Yuan-Tong Gu, Shawn Nielsen, \"Numerical investigation of mechanical and thermal dynamic properties of the industrial transformer\", International Journal of Computational Methods (IJCM), vol. 11, 2004.", "Magdy B. Eteiba, Essam A. Alzahab and Yomna O. Shaker, \"Steady State Temperature Distribution of Cast Resin Dry-type Transformer Based on New Thermal Model Using Finite Element Method\", International Journal of Electrical, Computer, Energetic, Electronic and Communication Engineering, vol. 4, pp. 361-365, 2010.\n[10]\tB. Vahdi, M. Eslamian and S. H. Hosseinian, \"Transient simulation of cast-resin dry-type transformers using FEM\", European Transactions on Electrical Power, vol. 21, pp. 363-379, 2011. \n[11]\tM. Florkowski, B. Florkowska, J. Furgal, P. Pajctk, \"The impact of oil and temperature on initial voltage distributions in transformer windings at ultra-fast stresses\", Annual Report Conference on Electrical Insulation and Dielectric Phenomena, 2010.\n[12]\tM. M. Isa, M. Z. A. A. Kadir, C. Gomes, N. Azis, M. Izadi, O. S. H. Alyozbaky, \"Analysis on Magnetic Flux Density and Core Loss for Hexagonal and Butt-lap Core Joint Transformers\", Annual IEEE Southern Power Electronics Conference (SPEC), 5-8 December, 2016. \n[13]\tChristian Freitag, Thomas Leibfried, \"Mixed Core Design for Power Transformers to Reduce Core Losses\", International Conference on Optimization of Electrical and Electronic Equipment (OPTIM), 25-27 May, 2017. \n[14]\thttps://wwwasw.comsol.com/multiphysics/finite-element-method\n[15]\tKirschen, Daniel, Fundamentals of Power System Economics, John Wiley & Sons Ltd., Chichester, Great Britain, 2004.\n[16]\tShekar, George Chen, Wilson, Jarman, \"Bridging in Contaminated Transformer Oil under DC and AC Electric Field\", Journal of Physics, vol. 472, 2013."]} The choice evaluation between oil-immersed and dry-type transformers is often controlled by cost, location, and application. This paper compares the electrical performance of liquid- filled and dry-type transformers, which will assist the customer to choose the right and efficient ones for particular applications. An accurate assessment of the time-average flux density, electric field intensity and voltage distribution in an oil-insulated and a dry-type transformer have been computed and investigated. The detailed transformer modeling and analysis has been carried out to determine electrical parameter distributions. The models of oil-immersed and dry-type transformers are developed and solved by using the finite element method (FEM) to compare the electrical parameters. The effects of non-uniform and non-coherent voltage gradient, flux density and electric field distribution on the power losses and insulation properties of transformers are studied in detail. The results show that, for the same voltage and kilo-volt-ampere (kVA) rating, oil-immersed transformers have better insulation properties and less hysteresis losses than the dry-type.

В данной работе исследована динамика плотности потока радона из грунта в атмосферу в зависимости от погодных условий. In this work, the dynamics of the density of the radon flux from the soil into the atmosphere depending on the weather conditions was studied.

In order to improve the customers’ continuous usage of electrical vehicles (EVs) and reduce the weight of the energy storage devices, wireless charging technology has been widely studied, updated, and commercialized in recent decades, regarding to its distinct superiority of great convenience and low risk. A higher coupling coefficient is the key factor that impacts the transmission efficiency, thus in most medium-power (hundreds of watts) to high-power (several kilowatts) wireless charging systems, ferrites are used to guide the magnetic flux and intensify the magnetic density. However, the weight of the ferrite itself puts an extra burden on the system, and the core loss during operation also reduces the total efficiency and output power. This paper proposes an optimized design algorithm based on a core-less method for the magnetic core, where the core loss and the coupling coefficient are consequently balanced, and the overall weight and efficiency of the system can be optimized. The iteration procedure is applied on the basis of removed ferrite length and thickness in the algorithm. In the simulation, a square coupler with a total volume of 300 mm × 150 mm, a circular coupler of 150 mm × 150 mm and a Double-D (DD) coupler of 300 mm × 150 mm are used to verify the advantages of the proposed method. The optimized ferrite structures are specific for each coupler shape, and the improvement is proved to be universal in current scale by means of 3-D finite element analysis.

Electrical machines utilized in domestic applications such as ceiling fans should have low losses and cost. Permanent magnets are used instead of rotor excitation to reduce losses. Therefore, not only the losses of the rotor winding are eliminated, but also the efficiency of the machine is increased. A surface inset consequent pole (SICP) machine has also been used to reduce costs. Because less magnets are utilized in this structure. The main problem is the affecting the residual flux density from temperature. In this paper, the SICP is analyzed by two-dimensional method, then magnetic flux density, Back-EMF, instantaneous torque and unbalanced magnetic forces are calculated. In this research, either the effect of temperature changes on the mentioned cases has been investigated, or two types of magnetization patterns include radial and parallel have been considered. 2022 IEEE. AKNOWLEDGMENT This publication was made possible by Qatar University Collaborative Research grant # [QUCG-CENG-21/22-1] from the Qatar University. The statements made herein are solely the responsibility of the authors. Scopus