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Search Results: 1 - 10 of 19770 matches for " Alexander Kozhanov "
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Spin Wave Scattering in Ferromagnetic Cross
Alexander Kozhanov,Alexander Anferov,Ajey P. Jacob,S. James Allen
Physics , 2012,
Abstract: Spin wave scattering in the right angle ferromagnetic cross was measured. Shape anisotropy defined magnetization ground states at zero biasing magnetic fields. Scattering of the spin waves in the center of ferromagnetic cross is strongly dependent on the amplitude and angle of the biasing magnetic field. Micromagnetic simulations indicate that low in-plane biasing magnetic fields rotate the magnetization of the cross center while the arms stay axially magnetized due to the shape anisotropy. We discuss effect of biasing magnetic fields on the spin wave scattering and approaches to an effective spin wave switch based on the fabricated structure.
Waveguide couplers for ferroelectric optical resonators
Ivan S. Grudinin,A. Kozhanov,N. Yu
Physics , 2014,
Abstract: We report a study of using the same material to fabricate a whispering gallery mode resonator and a coupler. Coupling to high Q whispering gallery modes of the lithium niobate resonator is demonstrated by means of the titanium-doped waveguide. The waveguide coupling approach opens possibilities for simpler and wider practical usage of whispering gallery mode resonators and their integration into optical devices.
Micro-Structured Ferromagnetic Tubes for Spin Wave Excitation
A. Kozhanov,D. Ouellette,M. Rodwell,D. W. Lee,S. X. Wang,S. J. Allen
Physics , 2010, DOI: 10.1063/1.3559475
Abstract: Micron scale ferromagnetic tubes placed on the ends of ferromagnetic CoTaZr spin waveguides are explored in order to enhance the excitation of Backward Volume Magnetostatic Spin Waves. The tubes produce a closed magnetic circuit about the signal line of the coplanar waveguide and are, at the same time, magnetically contiguous with the spin waveguide. This results in a 10 fold increase in spin wave amplitude. However, the tube geometry distorts the magnetic field near the spin waveguide and relatively high biasing magnetic fields are required to establish well defined spin waves. Only the lowest (uniform) spin wave mode is excited.
Resonant coupling of coplanar waveguides with ferromagnetic tubes
A. Kozhanov,D. Ouellette,M. Rodwell,D. W. Lee,S. X. Wang,S. J. Allen
Physics , 2009,
Abstract: Resonant coupling of coplanar waveguides is explored by wrapping proximate shorted ends of the waveguides with micron size ferromagnetic Co90Ta5Zr5 tubes. Ferromagnetic resonance and up to 7 outer surface modes are identified. Experimental results for these contorted rectangular tubes are in good agreement with micromagnetic simulations and model calculations of magnetostatic modes for an elliptical ferromagnetic tube. These results indicate that the modes are largely determined by tube topology and dimensions but less so by the detailed shape.
Dispersion and spin wave "tunneling" in nano-structured magnetostatic spin waveguides
A. Kozhanov,D. Ouellette,M. Rodwell,A. P. Jacob,D. W. Lee,S. X. Wang,S. J. Allen
Physics , 2008, DOI: 10.1063/1.3079767
Abstract: Magnetostatic spin wave dispersion and loss are measured in micron scale spin wave-guides in ferromagnetic, metallic CoTaZr. Results are in good agreement with model calculations of spin wave dispersion. The measured attenuation lengths, of the order of 3um, are several of orders of magnitude shorter than that predicted from eddy currents in these thin wires. Spin waves effectively "tunnel" through air gaps, produced by focused ion beam etching, as large as 1.5 um.
Dispersion in magnetostatic CoTaZr spin wave-guides
A. Kozhanov,D. Ouellette,Z. Griffith,M. Rodwell,A. P. Jacob,D. W. Lee,S. X. Wang,S. J. Allen
Physics , 2008, DOI: 10.1063/1.3063124
Abstract: Magnetostatic spin wave dispersion and loss are measured in micron scale spin wave-guides in ferromagnetic, metallic CoTaZr. Results are in good agreement with model calculations of spin wave dispersion and up to three different modes are identified. Attenuation lengths of the order of 3 microns are several of orders of magnitude shorter than that predicted from eddy currents in these thin wires.
Protection of Environment from Damaged Nuclear Station and Transparent Inflatable Blanket for Cities—Protection from Radioactive Dust and Chemical, Biological Weapons  [PDF]
Alexander Bolonkin
Journal of Environmental Protection (JEP) , 2011, DOI: 10.4236/jep.2011.24037
Abstract: The author, in a series of previous articles, designed the “AB Dome” made of transparent thin film supported by a small additional air overpressure for the purpose of covering a city or other important large installations or sub-regions. In present article the author offers a variation in which a damaged nuclear station can be quickly covered by such a cheap inflatable dome. By containing the radioactive dust from the damaged nuclear station, the danger zone is reduced to about 2 km2 rather than large regions which requires the resettlement of huge masses of people and which stops indus-try in large areas. If there is a big city (as Tokyo) near the nuclear disaster or there is already a dangerous amount of radioactive dust near a city, the city may also be covered by a large inflatable transparent Dome. The building of a gi-gantic inflatable AB Dome over an empty flat surface is not difficult. The cover is spread on a flat surface and a venti-lator (fan system) pumps air under the film cover and lifts the new dome into place but inflation takes many hours. However, to cover a city, garden, forest or other obstacle course in contrast to an empty, mowed field, the thin film cannot be easily deployed over building or trees without risking damage to it by snagging and other complications. This article proposes a new method which solves this problem. The design is a double film blanket filled by light gas such as, methane, hydrogen, or helium - although of these, methane will be the most practical and least likely to leak. Sections of this AB Blanket are lighter than air and will rise in the atmosphere. They can be made on a flat area serving as an as-sembly area and delivered by dirigible or helicopter to station at altitude over the city. Here they connect to the already assembled AB Blanket subassemblies, cover the city in an AB Dome and protect it from bad weather, chemical, bio-logical and radioactive fallout or particulates. After assembly of the dome is completed, the light gas can be replaced by (heavier but cheaper) air. Two projects for Tokyo (Japan) and Moscow (Russia) are used in this paper for sample computation.
Filters and Ultrafilters as Approximate Solutions in the Attainability Problems with Constraints of Asymptotic Character  [PDF]
Alexander Chentsov
Intelligent Information Management (IIM) , 2010, DOI: 10.4236/iim.2010.29062
Abstract: Abstract problems about attainability in topological spaces are considered. Some nonsequential version of the Warga approximate solutions is investigated: we use filters and ultrafilters of measurable spaces. Attrac- tion sets are constructed. AMS (MOS) subject classification. 46A, 49 K 40.
Using of High Altitude Wind Energy  [PDF]
Alexander Bolonkin
Smart Grid and Renewable Energy (SGRE) , 2011, DOI: 10.4236/sgre.2011.22010
Abstract: Ground based, wind energy extraction systems have reached their maximum capability. The limitations of current de-signs are: wind instability, high cost of installations, and small power output of a single unit. The wind energy industry needs of revolutionary ideas to increase the capabilities of wind installations. This article suggests a revolutionary innovation which produces a dramatic increase in power per unit and is independent of prevailing weather and at a lower cost per unit of energy extracted. The main innovation consists of large free-flying air rotors positioned at high altitude for power and air stream stability, and an energy cable transmission system between the air rotor and a ground based electric generator. The air rotor system flies at high altitude up to 14 km. A stability and control is provided and systems enable the changing of altitude. This article includes six examples having a high unit power output (up to 100 MW). The proposed examples provide the following main advantages: 1) Large power production capacity per unit—up to 5,000 - 10,000 times more than conventional ground-based rotor designs; 2) The rotor operates at high altitude of 1 - 14 km, where the wind flow is strong and steady; 3) Installation cost per unit energy is low; 4) The installation is environmentally friendly (no propeller noise).
Production of Freshwater and Energy from Earth’s Atmosphere  [PDF]
Alexander Bolonkin
Smart Grid and Renewable Energy (SGRE) , 2011, DOI: 10.4236/sgre.2011.22011
Abstract: The author offers a new, cheap method for the extraction of freshwater from the Earth’s atmosphere. The suggested method is fundamentally dictinct from all existing methods that extract freshwater from air. All other industrial methods extract water from a saline water source (in most cases from seawater). This new method may be used at any point in the Earth except the Polar Zones. It does not require long-distance freshwater transportation. If seawater is not utilized for increasing its productivity, this inexpensive new method is very environmentally-friendly. The author’s method has two working versions: 1) In the first variant warm (or hot) atmospheric air is lifted by the inflatable tube in a high altitude and atmospheric water vapor is condensed into freshwater: 2) in the second version, the warm air is pumped 20-30 meters under the sea-surface. In the first version, wind and solar heating of air are used for causing air flow. In version 2) wind and fans are used for causing air movment. The first method does not need energy, the second needs a small amount. Moreover, in variant 1) the freshwater has a high pressure (> 30 or more atm) and can be used for production of energy such as electricity and in that way the freshwater cost is lower. For increasing the productivity the seawater is injected into air and a solar air heater may be used. The solar air heater produces a huge amount of electricity as a very powerful electrical generation plant. The offered electricity installation is 100 - 200 times cheaper than any common electric plant of equivalent output.
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