Abstract: The presentation shows the advantages of superconductive synchronous condensers (SC), results of experimental investigation of 50 kVA HTSC alternator in a synchronous condenser mode and new developments of SC rated at 5 MVA intended for HTSC wind power plant to support its connection to a weak grid.
Abstract: Our investigations show that the addition of Ti, polyvalent titanium oxides or TiC powders (0.1-40 mm, amount: 10 wt%) can affect the formation of MgBx (x³4) inclusions and a redistribution of admixed oxygen resulting in the appearance of dispersed inclusions with near MgBO stoichiometry in the MgB2 matrix and thus influencing the critical current density and the critical magnetic fields of the materials. The highest Bc2 and Birr were obtained when powdered polyvalent titanium oxides (synthesized by electroerosion dispersion) or powdered titanium were added, but the critical magnetic fields were somewhat lower in the case of Ti additions. We show that Mg diffuses during the synthesis inside the grains of polyvalent titanium oxide, titanium carbide or titanium, which can affect the redistribution of boron and oxygen in the superconducting matrices and thus influence pinning and the superconducting properties.
Abstract: The paper develops analyses electromagnetic compatibility issues in electric vehicles. Particular techniques are developed involving special elements of tubular geometry based on the analytical solution of diffusion equation combined with standard finite elements, for analysis of electromagnetic shielding effectiveness in power cables due to power static converter operation. Particular simulations analyze the exposure levels due to variable frequency magnetic field on anatomically detailed human models in electric vehicle cabin environment. The results obtained have been compared to those found in the literature and to measured ones.
Abstract: The magnetic harmonic gear has been studied because of its high magnet use efficiency. However the magnetic harmonic gears are difficult to assemble. So, a new type of the magnetic harmonic gear was proposed. This magnetic gear has the stackable structure and is assembled easily. Thus far, it was studied its characteristics. In this study, we readjust its structure to step up its maximum transmit torque. The magnetic gear has parts which is constituted an iron plate and a segment magnet. In the past, it has never studied the ratio of iron to magnet. Therefore, we analyze the effect when they are changed the ratio of the iron to the magnet by simulation. We made the model which maximum transmitted torque is largest in the simulation. Then, we verify that the maximum transmitted torque is really improve. But it did not follow the results of the simulation. We discuss the reason of discrepancy.
Abstract: We calculate magnetic hysteresis loss of HTS coil under rotating magnetic field. No transport current through the coil is assumed other than induced current. In order to find the frequency and applied field direction dependence of the loss, we present the loss versus applied field amplitude curves, for the frequencies f=1, 10, 100 and 1000 Hz, for seven different orientations of magnetic field. The hysteretic loss through the SC component increases with increasing frequency. This behavior is a consequence of higher field penetration to the tape at higher frequencies.
Abstract: In this work, firstly we described the effect of freeze drying on modification of raw diatomite. And then, modified diatomite-leaf-like copper oxide (CuO) nanosheet composite was successfully prepared by surfactant-free in-situ chemical precipitation method. The structure, morphology and elemental analysis of CuO nanosheets and its composite were analyzed by field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), fourier transform infrared (FTIR) spectroscopy and energy dispersive X-ray spectroscopy (EDAX). Dimensions of leaf-like CuO nanosheets were approximately determined as 160 nm in width, 320 nm in length and 20 nm in thickness. According to the EDAX spectrum, leaf-like CuO nanosheets composed of Cu and O atoms without any impurity and also uniformly covered the entire surface of modified diatomite.
Abstract: In this study, copper oxide (CuO) nanostructures were successfully prepared by adding EG (ethylene glycol) and PEG (4000, 8000) (polyethylene glycol) via an in-situ chemical precipitation method. EG and PEG (4000, 8000) were effective for changing the particular size of CuO and we examined the effects of drying type such as freeze drying, muffle and horizontal furnace on the size of CuO nanostructure. The structure, morphology and elemental analysis of CuO nanostructure were analyzed by field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDS). Also, the CuO nanostructures showed excellent electrical conductivity by the changing of PEG’s molecular weight and drying processes.
Abstract: Electrical characteristics and morphology of nanocomposite films composed of two different polystyrene (PS) latexes impregnated with multi-walled carbon nanotubes (MWCNT) in the range between 0 wt% and 20 wt% were assessed by considering photon transmission (UV-Vis) technique and electrical conductivity measurements. Emulsion polymerization technique was employed both to synthesize very fine PS particles dispersed in water and to tailor the sizes of the PS particles as 382 nm and 560 nm, respectively. PS/MWCNT nanocomposite films were obtained from the liquid form on glass substrates via drop-casting method and all they dried at 40 QUOTE C. Each dried sample was then annealed at varying temperatures between 100 QUOTE C and 250 QUOTE C for 10 min. The surface conductivity QUOTE of each annealed film at 250 QUOTE C was measured and was found to increase dramatically above a certain mass fraction of MWCNT content, QUOTE . Each set of PS/MWCNT nanocomposite film had a similar electrical percolation threshold of QUOTE =1.5 wt% as the MWCNT content and critical exponents of QUOTE were found to be 2.64 and 1.19 for 382 nm and 560 nm PS latex systems, respectively.
Abstract: In this study, pyrene (P) tagged polystyrene (PS) latex dispersions and silver nanoparticles (AgNPs) were mixed at various weight fractions in the range between 0 and 50 wt%. The prepared mixtures were dropped on the glass substrates by considering drop casting method and were dried at the room temperature. The resultant powder films were then exposed to solvent vapor to monitor how film formation and morphological behaviors of PS/AgNPs composites are altered. Film formation behavior of composites was assessed via fast transient fluorescence (FTRF) which measures the fluorescence lifetimes of P from its decay traces during vapor exposure process. It was observed that pyrene lifetimes decreased as vapor exposure time, t increased. A Stern–Volmer kinetic analysis was used for low quenching efficiencies to interpret the decrease in pyrene lifetimes. UV-Vis (UVV) technique was employed to monitor optical transparency of the films. In the range of 0-20 wt% of AgNPs content, smooth and transparent films were obtained. However, above this range, the films were seen that they have low transparency and poor film formation since the increment in AgNPs content was lead to aggregations. The Prager–Tirrel model was employed to the FTRF data to obtain back-and-forth frequencies, ν, of the reptating PS chains during vapor induced film formation process. SEM images of the samples were taken after film formation process is completed and were found to be consistent with optical and fluorescence quenching data.
Abstract: The magnetic particles of iron oxides are promising materials for the purification of water from ions of heavy metals and radionuclides. Their advantage compared to other sorbents is the ability to extract by applied magnetic field, which greatly simplifies the task of extraction, separation and processing in cleaning technologies. The aim of this work is investigation of temperature and concentration of iron in the solution effect on the phase composition, nanoparticle size and their magnetization.
Phase magnetite in the sample increases with increasing temperature and the magnetization decreases slightly with increasing the initial concentration of iron in solution. We found that regardless of the conditions of deposition formed spherical particles whose average size ranges from 7 to 15 nm. The sorptive capacity of the particles is virtually independent of the phase composition and for cobalt is about 18 mg/g. For sorption-based material magnetic particles Fe3O4 recommended to carry out the deposition process at a temperature not lower than 80°C. The concentration of iron in solution must be within 0,15–0,3M. The particles obtained contain in their composition at least 90 wt.% of magnetite phase and are characterized by a magnetization in the range of 65–70 A·m2/kg. Also in the paper is comparing efficiency of extraction and sorption capacity for cobalt particles by different phase of magnetite and hematite.