Examination of Levitation of Thin Non-Magnetic Conductor by AC Electoromagnet Type Electro Dynamic Suspension
Because transportation by magnetic levitation has the advantage of not contacting, it has various good points. Conventional studies of electro dynamic suspension (EDS) are aimed on the large-scale applications, and use the non magnetic conductor of 1mm or more in thickness. However, in theoretical, it is possible that the thinner non magnetic conductor of less than 1mm in thickness levitate, using higher frequency or larger magnetomotive force. Therefore, applications to a smaller levitation model can be expected. In this paper, the relation between lift force and the temperature rise in the conductor is examined from the numerical analysis, when we consider a smaller levitation model. Skin effect and electromagnetic force between gaps are taken into account. These results are verified by experiments.
Electro-magnetic and electrodynamic sustentation comparison No . A 20110228-89
The aim of the present analysis is to compare electro-dynamic (EDS) and electromagnetic (EMS) sustentation systems. For the electro-dynamic solution, the simplified model will be a sine wave MMF generated by a DC conducting layer in front of a semi-infinite conducting space. For the electro-magnetic solution, an electromagnet in front of iron will be considered. In a second step a more precise model is presented, allowing a sensitivity analysis of the main design parameters: speed, air gap, conducting layer thickness, pole pitch, etc 1 SIMPLIFIED METHODOLOGY 1.1 Electro-dynamic sustentation The system is defined as two semi-infinite spaces air and conducting material with a sine tangential magnetic field moving at the surface (Fig 1). The main variables are: V r vector potential Such as for the magnetic flux density B: V t o r B r r r = [1] [1] In air : 0 = ΔV r r Laplace’s law [2] In a material with constant resistivity (ρ) and permeability (μ): t V V ∂ ∂ = Δ r r r ρ μ Poisson’s law [3] Figure 1. EDS semi-infinite spaces. Two half-spaces, air and conducting material, are separated by a plane. On the surface, on the air side, an ideal conducting layer creates an alternating magnetic field in the y direction at the level z = 0: τ π ' sin ˆ 0 0 ' y H H y = with τ = pole pitch If the excitation layer moves at the speed v in the y’ direction, it comes: vt y y + = ' ( ) ⎟ ⎠ ⎞ ⎜ ⎝ ⎛ + = + = t v y H vt y H H y τ π τ π τ π sin ˆ sin ˆ 0 0 0 ⎟ ⎠ ⎞ ⎜ ⎝ ⎛ + = t y H ω τ π sin ˆ 0 With τ π ω v = It is possible to associate complex numbers to sine expressions: Air ( ) Ω = = + 0 / 0 0 ˆ ˆ H e H H t y j y ω τ π [4] The vector potential is co-linear with the electric field E, in the x direction. By analogy, the vector potential can be written as: ) , , ( t z y V i V x = r Equation [3] becomes: Conducting material μ, ρ μ0, ρ x
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air at VA facilities, one of the many pieces of unfinished business beyond those major issues that we discussed in our Commentary. We agree that all facilities where current and past military personnel serve and receive treatment should be 100% smoke-free and note the recent Institute of Medicine report Combating Tobacco in Military and Veteran Populations. The report, which was commissioned by the Department of Defense (DOD) in 2007, calls for the DOD to set a timeline to eliminate smoking on military installations. The report also recommends that the DOD stop selling tobacco products in military commissaries and exchanges, prohibit tobacco use anywhere on military installations, and treat tobacco use in the same way as other health-related behaviors, such as alcohol abuse and poor physical fitness. We join Matthews and the Institute of Medicine in urging the VA and the DOD to take more immediate steps to protect the health of the men and women who serve in the armed services, as well as the civilians (such as Dr Matthews) working to serve them.