The authors are investigating the possibility of using bulk magnets in the Maglev system. It is considered that bulk magnets for the Maglev system must be composed of numerous superconducting bulks ...arranged in rows and columns for each magnet pole because a bulk superconductor with a high critical current density doesn't have a sufficiently large size for Maglev magnet. Therefore, it is necessary to examine the flux-trapping characteristic of superconducting bulks arranged in array. Flux-trapping experiments are performed using the melt-processed YBaCuO superconducting bulks arranged in rows and columns, in which each bulk individually has a magnetizing coil, and the bulks are magnetized by field cooling. It is found that, when the superconducting bulks are arranged in rows and columns, the trapped flux density and the generated magnetic field are smaller than those when a superconducting bulk is used alone. The rate of decreases in the trapped flux density and the generated magnetic field becomes larger with increases in the number of superconducting bulks arranged in array. The trapped flux decreases conspicuously in particular at a superconducting bulk surrounded by other superconducting bulks.
A detailed observation was conducted on Fe, Mn, Cu and Zn in the composts derived from seafood processing by-product, garbage, swine manure and sewage sludge, respectively, as well as in amended ...farmlands. All elements were at lower levels of total contents but a higher percentage of water-soluble and exchangeable forms in composted seafood processing byproduct and composted garbage than in composted swine manure and composted sewage sludge. Total contents increased in the order: composted seafood processing by-product ≈ composted garbage < composted swine manure < composted sewage sludge. The applications of composted seafood processing by-product and composted garbage have neither caused Fe, Mn, Cu and Zn accumulation nor changed their distribution in soils; while the application of composted swine manure has largely increased Cu and Zn contents in soils, mainly in organic matter-bound form, and that of composted sewage sludge increased Mn, Cu and Zn in soils mainly in carbonate-bond and Fe-Mn oxides-bound ones. Fe is an exception, its total contents in soils decreased with the applications of composts except for composted garbage. Also, the rainfall and irrigation were another two main factors that affected available elements in soils.
We have measured trapped field distributions by scanning a Hall probe on various rectangular YBCO bulk superconductors and studied the effects of field dependence of
J
c bulk thickness and bulk size ...on the trapped field. The trapped field could be increased by increasing the bulk thickness and size. However, a saturation was observed for the maximum thickness. We also calculated the distribution of trapped field taking account of the field dependence of
J
c. Experimental trapped field distributions were in good agreement with our calculated values when we used the
J
c-B
curves obtained from a d.c. magnetization measurement for samples.
Two methods of hydrogen separation using proton-conducting perovskites, electrochemical hydrogen pumping with proton-conducting electrolytes and hydrogen sieving through protonic–electronic mixed ...conductors, are stated. In the former case, high temperature proton conductors (HTPCs) enable the hydrogen transport by external application of electricity. In the latter case, it is a fundamental concern how the protonic and electronic charge carriers coexist in oxides to allow hydrogen permeation. Experimental results and the problems for future investigations are discussed.
Metal-on-metal (MoM) bearings have become popular due to a major advantage over metal-on-polymer bearings for total hip arthroplasty in that the larger femoral head and hydrodynamic lubrication of ...the former reduce the rate of wear. However, concerns remain regarding adverse reactions to metal debris including metallosis caused by metal wear generated at the taper-head interface and another modular junction. Our group has hypothesized that carbon ion implantation (CII) may improve metal wear properties. The purpose of this study was to investigate the wear properties and friction coefficients of CII surfaces with an aim to ultimately apply these surfaces to MoM bearings in artificial joints. CII was applied to cobalt-chromium-molybdenum (Co-Cr-Mo) alloy substrates by plasma source ion implantation. The substrates were characterized using scanning electron microscopy and a 3D measuring laser microscope. Sliding contact tests were performed with a simple geometry pin-on-plate wear tester at a load of 2.5 N, a calculated contact pressure of 38.5 MPa (max: 57.8 MPa), a reciprocating velocity of 30 mm/s, a stroke length of 60 mm, and a reciprocating cycle count of 172,800 cycles. The surfaces of the CII substrates were generally featureless with a smooth surface topography at the same level as untreated Co-Cr-Mo alloy. Compared to the untreated Co-Cr-Mo alloy, the CII-treated bearings had lower friction coefficients, higher resistance to catastrophic damage, and prevented the adhesion of wear debris. The results of this study suggest that the CII surface stabilizes the wear status due to the low friction coefficient and low infiltration of partner materials, and these properties also prevent the adhesion of wear debris and inhibit excessive wear. Carbon is considered to be biologically inert; therefore, CII is anticipated to be applicable to the bearing surfaces of MoM prostheses.
A moving of the superconducting wire due to an electromagnetic force induces heat, and that is one factor of instabilities in superconducting coils. There is a wire motion under a DC operation; on ...the other hand, there is a mechanical loss under an AC operation. To prevent those movements, it is effective to enhance the winding tension at coil-operating temperature. For that purpose, we propose the use of a Dyneema fiber reinforced plastic (DFRP), which has a negative thermal expansion coefficient, as the bobbin of the superconducting coils. To investigate a contribution to improvement of stability due to the DFRP, we performed DC and AC experiments. In the DC experiment, rates of the attainment to the critical current were evaluated by quench training measurements, and in the AC experiment, losses were measured. In both experiments, the thermal expansion characteristics of the DFRP prevented the wire's movement, therefore it was demonstrated that the use of the DFRP bobbin was effective about the improvement of stability.
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