Sinusoidal back-EMF waveform of vernier Permanent Magnet (PM) machines is analyzed in this paper. An analytical expression of Electromotive Force (EMF) of electric machines including vernier machines is developed to a...
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Sinusoidal back-EMF waveform of vernier Permanent Magnet (PM) machines is analyzed in this paper. An analytical expression of Electromotive Force (EMF) of electric machines including vernier machines is developed to analyze EMF harmonics, and the effect of vernier PM machine pole ratio, the ratio of number of rotor poles to stator poles, on the EMF waveform. Moreover, this paper represents several Finite Element Analysis (FEA) models to verify the analysis based on the proposed expression, and the effect of tooth width ratio, which is the ratio of tooth width to tooth pitch, on back-EMF of vernier PM machines, and optimal tooth width ratio is obtained and verified by FEA. Finally, this paper makes comparisons between EMF waveform of vernier PM machines and that of traditional PM machines from the point of view of analytical EMF expression.
We propose a method—the Fourier energy spectrum to identify filamentary,periodic and homogeneous dielectric barrier discharges (DBDs) based on fast Fourier transform techniques(FFT) of the discharge *** radial Fourie...
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We propose a method—the Fourier energy spectrum to identify filamentary,periodic and homogeneous dielectric barrier discharges (DBDs) based on fast Fourier transform techniques(FFT) of the discharge *** radial Fourier energy spectrum(RFES) shows only one peak and the angular Fourier energy spectrum(AFES) shows a serious of random peaks in a filamentary *** RFES and AFES show a serious of periodic peaks in a periodic *** addition to a direct current component,there is no peak for the RFES and AFES in a homogeneous *** an increase of the applied voltage,the RFES gradually shifts right and the AFES gradually shifts up in air at atmospheric pressure with a mesh electrode,it means that the spatial period of the discharge image gradually decreases,and the periodic characteristic of the discharge is more *** results indicate that the method is simple and effective to identify the three different kinds of DBDs.
The influence of oxygen content and heat treatment on the evolution of carbides in a powder metallurgy (PM) Ni-base superalloy was characterized. The results reveal that oxygen content has little influence on the pr...
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The influence of oxygen content and heat treatment on the evolution of carbides in a powder metallurgy (PM) Ni-base superalloy was characterized. The results reveal that oxygen content has little influence on the precipitation of carbides inside the particles. However, under the consolidated state, stable Ti oxides on the particle surface act as nuclei for the precipitation of prior particle boundaries (PPB). Also, oxygen can diffuse internally along grain boundaries under compressive stress, which favors the precipitation of carbides inside the particles. Therefore, a higher amount of carbides will appear with more oxygen content in the case of consolidated alloys. It is also observed that PPB can be disrupted into discontinuous particles at 1200℃, but this carbide network is hard to be eliminated completely. The combined MC-M23C6 morphology approves the nucleation and growth mechanism of carbide evolution.
Using transverse magnetic field(TMF) is one of the most important ways to improve the electric life and the breaking capacity of DC *** order to better understand the influence of transverse magnetic field on arc dura...
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ISBN:
(纸本)9781622763139
Using transverse magnetic field(TMF) is one of the most important ways to improve the electric life and the breaking capacity of DC *** order to better understand the influence of transverse magnetic field on arc duration,a series of experiments were conducted under external transverse magnetic field with 4 relay contacts in a DC 580V/60A *** permanent magnets,the transverse magnetic field is obtained and the magnetic flux density at center magnet can be varied from 80 to 320 *** results show that the making arc duration is independent of magnetic flux density,but the breaking arc duration is decreased monotonically with the increase of the magnetic flux *** addition,the gradient |Δt/ΔB| of the breaking arc duration is decreased with the increase of the magnetic flux density,which means the curve of t-B tends to be flat.
For the current transformers (CTs) on the delta side measure the line current instead of the phase current, line current differential protection is adopted in transformers connected in wye-delta mode currently. Howeve...
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Summary form only given. A very large number of serious human and animal diseases such as AIDS, SARS, common cold, human and avian influenza, chickenpox, and several others are caused by viral infections. The infectio...
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Summary form only given. A very large number of serious human and animal diseases such as AIDS, SARS, common cold, human and avian influenza, chickenpox, and several others are caused by viral infections. The infectious agents of these diseases are virus nanoparticles (virions) that contain DNA/RNA strands encased in a capsid protein coat and in some cases also in an outer lipid envelope. The virions are usually transmitted from the infected cases through airborne dissemination or diffusion during nosocomial transfusion of blood or body liquids. The onset of the viral infection is usually heralded by the entry of the virion's genetic material into the intracellular space followed by the uncontrollable integration with the host DNA and virus replication. Despite decades of research, virion detection, pre-emptive and post-infection anti-viral treatments and immunotherapies remain ineffective and the morbidity and mortality rates due to the associated infections remain high.
Plasma jet devices generate plasmas in an open space (surrounding air) rather than in lieu of confined discharge gaps. Hence, they can be used for direct treatment and there is also no limitation on the size of the ob...
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Plasma jet devices generate plasmas in an open space (surrounding air) rather than in lieu of confined discharge gaps. Hence, they can be used for direct treatment and there is also no limitation on the size of the object. However, to the best of our knowledge, the dimensions of plasma jet nozzles that have been reported in the literature are mainly very small (sub-millimeter to several millimeters) making treatment of a large area difficult, only few large plasma jets are developed. One way to overcome this shortcoming is the use of plasma jet arrays. However, since individual plasma plumes generated by these plasma jet arrays are independent and not merged, it is relatively difficult to achieve uniform treatment effects.
Wide-area communication system is supporting platform for wide-area relay protection (WARP) exchanging information, which includes not only visible physical communication equipment and links, but also communication pr...
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This paper devotes itself to the experimental study on surface flashover characteristics of insulating material, which is closely connected to the compact pulsed power system operating in vacuum. The rated voltage of ...
This paper devotes itself to the experimental study on surface flashover characteristics of insulating material, which is closely connected to the compact pulsed power system operating in vacuum. The rated voltage of the pulsed power source is several kV and the peak current is several kA. To simulate the actual operating condition and possible failure mode of pulsed power system, a series of experiments are performed to validate the adaptability of high pulsed power device in vacuum. This paper concentrates on the mechanism of surface flashover in vacuum and corresponding influence factors. Different metal electrode materials, different creepage distances and the interference effect of hot plasma have been studied. Research indicates that external plasma plays a key role in the formation of surface flashover. In medium vacuum (1×10 -3 Pa), the surface flashover voltage of 3mm surface creeping distance on organic glass is above 17 kV; But if there is external plasma source, the flashover voltage would reduce significantly with the increase of plasma density; flashover voltage would rush to 1 kV or lower. Based on the experiment study, some measures are taken on the several kilovolts pulsed power source (PPS) produced in prior work. The device can operate stably in the vacuum of 10 -3 Pa.
A novel fault phase selector for double-circuit transmission lines is presented. The fault type is determined with the superimposed components and steady state components of fault voltage. According to the determined ...
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