966 resultados para generator derivatives


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We thank European Commission (project “PET BRAIN: Mapping the brain with PET radiolabeled cannabinoid CB1 ligands”; FP7-People-2009-IAPP; Grant Agreement N.25142).

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I thank SERC for a CASE studentship (to RG. Giles) with the former Fisons Pharmaceuticals division (with Dr. S. C. Eyley) and Dr. B. R. Buckley, of this department, for provided helpful comments on an earlier version of the manuscript.

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A DSP implementation of Space Vector PWM (SVPWM) using constant V/Hz control for the open winding doubly-fed generator is proposed. This control of SVPWM modulation mode and open winding structure combination has the high voltage utilization ratio, greatly improves the control precision of the system, and reduces the stator winding output current distortion rate, though the complexity of the system is increased. This paper describes the basic principle of SVPWM and discusses the particularity of SVPWM waveform generated by hybrid vector under the condition of open winding. This method is applied to a state of doubly-fed wind power generator. The experimental verification shows that this control method can make the output voltage amplitude of the doubly-fed induction generator be 380V and the frequency be 50Hz by using of TMS32028335 chip based on constant V/Hz control of symmetric SVPWM modulation wave.

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A novel open-winding brushless doubly-fed generator (BDFG) system with two two-level bidirectional converters is proposed. This topology is equivalent to a three-level bidirectional converter connected to the typical BDFG, but solves the unbalanced-voltage-division problem of DC capacitor in the three-level converter, and has lower converter capacity, more flexible control mode, and better fault-tolerant ability. The direct power control (DPC) based on the twelve sections is adopted to implement the power tracking of the open-winding BDFG system, which is compared with the typical BDFG DPC system based on the six and twelve sections to verify the advantages of the proposed scheme.

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The solid-state pyrolysis of organometallic derivatives of a cyclotriphosphazene is demonstrated to be a new, simple and versatile solid-state templating method for obtaining single-crystal micro- and nanocrystals of transition and valve metal oxides. The technique, when applied to Mo-containing organometallics N3P3[OC6H4CH2CN·Mo(CO)5]6 and N3P3[OC6H4CH2CN·Mo(CO)4 py]6, results in stand-alone and surface-deposited lamellar MoO3 single crystals, as determined by electron and atomic force microscopies and X-ray diffraction. The size and morphology of the resulting crystals can be tuned by the composition of the precursor. X-ray photoelectron and infrared spectroscopies indicate that the deposition of highly lamellar MoO3 directly on an oxidized (400 nm SiO2) surface or (100) single-crystal silicon surfaces yields a layered uniphasic single-crystal film formed by cluster diffusion on the surface during pyrolysis of the metal-carbonyl derivatives. For MoO3 in its layered form, this provides a new route to an important intercalation material for high energy density battery materials.

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The cyclic phosphazene trimers [N3P3(OC6H5)5OC5H4N·Ti(Cp)2Cl][PF6] (3), [N3P3(OC6H4CH2CN·Ti(Cp)2Cl)6][PF6]6 (4), [N3P3(OC6H4-But)5(OC6H4CH2CN·Ti(Cp)2Cl)][PF6] (5), [N3P3(OC6H5)5C6H4CH2CN·Ru(Cp)(PPh3)2][PF6] (6), [N3P3(OC6H5)5C6H4CH2CN·Fe(Cp)(dppe)][PF6] (7) and N3P3(OC6H5)5OC5H4N·W(CO)5 (8) were prepared and characterized. As a model, the simple compounds [HOC5H5N·Ti(Cp)2Cl]PF6 (1) and [HOC6H4CH2CN·Ti(Cp)2Cl]PF6 (2) were also prepared and characterized. Pyrolysis of the organometallic cyclic trimers in air yields metallic nanostructured materials, which according to transmission and scanning electron microscopy (TEM/SEM), energy-dispersive X-ray microanalysis (EDX), and IR data, can be formulated as either a metal oxide, metal pyrophosphate or a mixture in some cases, depending on the nature and quantity of the metal, characteristics of the organic spacer and the auxiliary substituent attached to the phosphorus cycle. Atomic force microscopy (AFM) data indicate the formation of small island and striate nanostructures. A plausible formation mechanism which involves the formation of a cyclomatrix is proposed, and the pyrolysis of the organometallic cyclic phosphazene polymer as a new and general method for obtaining metallic nanostructured materials is discussed.