MANYETİZMA Manyetizmanın Tarihi Manyetizmanın Tanımı Mıknatıslanmanın Tanımı Doyma Mıknatıslanması Manyetik Bölgeler MANYETİZMA ÇEŞİTLERİ Paramanyetizma Diyamanyetizma Ferromanyetizma Antiferromanyetizma Ferrimanyetizma MANYETİK... more
MANYETİZMA Manyetizmanın Tarihi Manyetizmanın Tanımı Mıknatıslanmanın Tanımı Doyma Mıknatıslanması Manyetik Bölgeler MANYETİZMA ÇEŞİTLERİ Paramanyetizma Diyamanyetizma Ferromanyetizma Antiferromanyetizma Ferrimanyetizma MANYETİK ALINGANLIK Manyetik Alınganlığın Tanımı Manyetik Alınganlık Ölçüm Yöntemi Manyetik Alınganlık Ölçüm Sistemi
Magnetic susceptibility is a measure of how much a material will become magnetized in an applied magnetic field. Magnetic susceptibility, X is a ratio of magnetization, M to the magnetic field intensity, H. X > 0 is paramagnetism, and X <... more
Magnetic susceptibility is a measure of how much a material will become magnetized in an applied magnetic field. Magnetic susceptibility, X is a ratio of magnetization, M to the magnetic field intensity, H. X > 0 is paramagnetism, and X < 0 is diamagnetism. The objective of the experiment is to determine the magnetic susceptibilities of FeCl_3 solution and water. The volume and mass susceptibilities of the solution are also determined. The experiment consists of two parts. The first part is to measure the magnetic flux as a function of the current. The second part is to measure the change in the liquid column as a function of current. The best value for magnetic flux is obtained at I = 0 A. For series connection, Φ0 = (1.54 ± 0.01) x 10-6 mWb. For parallel connection, Φ0 = [(1.61 x 10-6) ± (3.18 x 10-4)] mWb. It is obtained that FeCl_3 is paramagnetic and water is diamagnetic. In particular, for FeCl_3, X = 0.04 ± (6.76 x 10-6). Whereas, for water, X = - (1.9 ± 7.0) x 10-3. The volume and mass susceptibilities of FeCl_3 are only managed to be simplified algebraically.
A detailed analysis of a mono-stable vertical diamagnetic levitation (VDL) system for optimal vibration energy harvesting is presented. Initial studies showed that simple analytical techniques such as the dipole model and the image method... more
A detailed analysis of a mono-stable vertical diamagnetic levitation (VDL) system for optimal vibration energy harvesting is presented. Initial studies showed that simple analytical techniques such as the dipole model and the image method provide useful guideline for understanding the potential of a diamagnetic levitation system, however, it is discussed here that the more accurate semi-analytical techniques such as the thin coil model and the discrete volume method are needed for quantitative optimization and design of the VDL system. With the semi-analytical techniques, the influence of the cylindrical geometry of the floating magnet, the lifting magnet and the diamagnetic plate are parametrically studied to assess their effects on the levitation gap, size of the system and the natural frequency. For efficient vibration energy harvesting using the VDL system, ways to mitigate eddy current damping and a coil geometry for transduction are critically discussed. With the optimized parameters, an experimental system is realized which showed a hardening type nonlinearity. The results show an overall efficiency of 1.54 percent, a root mean square (rms) power output of 1.72 mW when excited at a peak acceleration of 0.081 m/s 2 and at a frequency of 2.1 Hz.
A new form of bi-stable system based on the passive friction-free horizontal diamagnetic levitation mechanism is proposed in this article. The system is comprised of twelve magnets which create a bi-stable potential well for a centrally... more
A new form of bi-stable system based on the passive friction-free horizontal diamagnetic levitation mechanism is proposed in this article. The system is comprised of twelve magnets which create a bi-stable potential well for a centrally located floating magnet. The levitation is stabilized in the horizontal direction by the diamagnetic repulsion from pyrolytic graphite plates which are placed on either side of the floating magnet. Theoretical modeling is discussed involving the superposition of the magnetic fields and magnetic forces, which include semi-analytical equations, from the various magnets in the system to determine the characteristics of the bi-stable potential well. Stability equations for achieving static bi-stability and for maintaining stable levitation during intra-well and inter-well motion were discussed. An experimental prototype is presented whose frequency response characteristics were validated for varying input sinusoidal excitations. Once the dynamics of the bi-stable system were validated, copper coils are incorporated into the diamagnetic plates to enable the vibration energy harvesting capability of the levitation mechanism. The floating magnet underwent chaotic and interwell motions for a range of input sinusoidal excitation frequencies, 5.8 Hz – 8 Hz, at input accelerations of 1.99 m/s 2 to 3.79 m/s 2 , and peak system efficiencies of close to 2.5% were achieved.
A Horizontal Diamagnetic Levitation Based Low Frequency Vibration Energy Harvester This paper investigates a horizontal diamagnetic levitation (HDL) system for vibration energy harvesting in contrast to the vertical diamagnetic levitation... more
A Horizontal Diamagnetic Levitation Based Low Frequency Vibration Energy Harvester This paper investigates a horizontal diamagnetic levitation (HDL) system for vibration energy harvesting in contrast to the vertical diamagnetic levitation (VDL) system recently proposed by Wang et al. (2013, " A Magnetically Levitated Vibration Energy Harvester, " Smart Mater. Struct., 22(5), p. 055016). In this configuration, two large magnets, alias lifting magnets (LMs), are arranged co-axially at a distance such that in between them a magnet, alias floating magnet (FM), is passively levitated at a laterally offset equilibrium position. The levitation is stabilized in the horizontal direction by two diamagnetic plates (DPs) made of pyrolytic graphite placed on each side of the FM. This HDL configuration mitigates the limitation on the amplitude of the FM imposed in the VDL configuration and exploits the ability to tailor the geometry to meet specific applications due to its frequency tuning capability. A simple circular coil geometry is designed to replace a portion of the pyrolytic graphite plate without sacrificing the stability of the levitation for trans-duction. An experimental setup exhibits a weak softening frequency response and validates the theoretical findings; at an input root mean square (RMS) acceleration of 0.0434 m/s 2 and at a resonant frequency of 1.2 Hz, the prototype generated a RMS power of 3.6 lW with an average system efficiency of 1.93%.
This article identifies and studies key parameters that characterize a horizontal diamagnetic levitation mechanism–based low frequency vibration energy harvester with the aim of enhancing performance metrics such as efficiency and volume... more
This article identifies and studies key parameters that characterize a horizontal diamagnetic levitation mechanism–based low frequency vibration energy harvester with the aim of enhancing performance metrics such as efficiency and volume figure of merit. The horizontal diamagnetic levitation mechanism comprises three permanent magnets and two diamag-netic plates. Two of the magnets, lifting magnets, are placed co-axially at a distance such that each attracts a centrally located magnet, floating magnet, to balance its weight. This floating magnet is flanked closely by two diamagnetic plates which stabilize the levitation in the axial direction. The influence of the geometry of the floating magnet, the lifting magnet , and the diamagnetic plate is parametrically studied to quantify their effects on the size, stability of the levitation mechanism, and the resonant frequency of the floating magnet. For vibration energy harvesting using the horizontal dia-magnetic levitation mechanism, a coil geometry and eddy current damping are critically discussed. Based on the analysis, an efficient experimental system is setup which showed a softening frequency response with an average system efficiency of 25.8% and a volume figure of merit of 0.23% when excited at a root mean square acceleration of 0.0546 m/s 2 and at a frequency of 1.9 Hz.
Magneto-optical properties are wide and span various applications such as magnetic field sensing, imaging technologies, security encoding... In this work, we have revisited the all-optical Inverse Faraday effect method to measure the... more
Magneto-optical properties are wide and span various applications such as magnetic field sensing, imaging technologies, security encoding... In this work, we have revisited the all-optical Inverse Faraday effect method to measure the Faraday rotation angle and determine the Verdet constant of diamagnetic/paramagnetic liquid solutions. We show that using a picosecond laser source the Inverse Faraday effect enables to reach magnetic flux densities in liquids in the range of 1-100 T with average power ranging below 10 mW, levels which are comparable or higher than those obtained using electromagnets to generate pulsed magnetic fields. This all-optical method with no pump-probe scheme has the advantage that it requires small volumes (<100 µl) and enables in situ fast and efficient static measurements. We further show it is possible to determine the Verdet constant of solutes in binary diluted solutions and we also emphasize that chiral molecules exhibit considerable enantiomeric diff...
ABSTRACTThe induced magnetic moment of a biased semiconductor tunnel-coupled parallel double quantum wire system is examined here. The wires are in a series arrangement with tunnel coupling to each other and to leads. Their parallel... more
ABSTRACTThe induced magnetic moment of a biased semiconductor tunnel-coupled parallel double quantum wire system is examined here. The wires are in a series arrangement with tunnel coupling to each other and to leads. Their parallel lengths and associated continuous spectrum are taken in the direction perpendicular to the lead-to-lead current. The equations of motion for the double-wire electron Green's function are formulated and analyzed using the transfer-tunneling Hamiltonian formalism. We determine the average magnetic moment of the double-wire system induced by a magnetic field applied perpendicular to the plane of the structure and we show that there are crossovers between diamagnetic and paramagnetic behavior, depending on the bias voltage, equilibrium chemical potential of the leads and temperature.
A crystal engineering approach is used to stabilize a radical anion in the crystalline state and to modulate the separation distance within π-stacks of anion radicals. Alkali metal salts of 2,3-dicyano-5,6-dichlorosemiquinone (C8Cl2N2O2,... more
A crystal engineering approach is used to stabilize a radical anion in the crystalline state and to modulate the separation distance within π-stacks of anion radicals. Alkali metal salts of 2,3-dicyano-5,6-dichlorosemiquinone (C8Cl2N2O2, DDQ∙- radical anions were prepared and their crystal structures determined: LiDDQ·2H2O·(CH3)2CO, RbDDQ·2H2O and CsDDQ·2H2O. In these structures, stacked dimers of radical anions are formed within π-stacked columns. Within the stacked dimers, interplanar separation distances are significantly shorter than the sum of the van der Waals radii for two C atoms; the shortest is 2.812 Å for the Li salt and the longest is 2.925 Å for the Cs salt. Diamagnetic character, observed by electron paramagnetic resonance spectroscopy, indicates spin-coupling of the unpaired electrons within the radical anion dimer. The electron-rich cyano substituents on DDQ∙- influence the electron redistribution within the ring skeleton. The crystalline compounds are also character...