Implementation of manganese–bismuth(MnBi)alloys as high-performance permanent magnets is a challenge for physicists and engineers because the ferromagnetic low-temperature phase(LTP)is not exclusively obtained.In thi...Implementation of manganese–bismuth(MnBi)alloys as high-performance permanent magnets is a challenge for physicists and engineers because the ferromagnetic low-temperature phase(LTP)is not exclusively obtained.In this work,melting powered by four commercial magnetrons of 2000–2500 W in a microwave furnace is demonstrated as a new route to alloy MnBi.Under an argon atmosphere,microwave heating transferred to pieces of broken Bi ingots and Mn flakes for 2 h gave rise to products of inhomogeneous composition and morphology.Scanning electron micrographs were classified into three regions according to morphology and elemental composition.Cubic-like clusters characterized as Mn precipitated over light solidified Bi-rich regions,and the MnBi phase was formed in homogeneous regions with a balanced composition between Mn and Bi.A ferromagnetic hysteresis loop was obtained in the ground powder with a coercivity of 40 kA/m.Subsequent annealing at 553 K under a pressure of 414 kPa for 12 h enhanced the MnBi phase with extended regions of balanced composition.It follows that the coercivity was increased to 60 kA/m.However,remanent magnetization was slightly reduced.This MnBi alloyed by microwave radiation can be further used in rare-earth-free magnets.展开更多
A new accurate calculation method of electric power harmonic parameters was presented. Based on the delay time theorem of Fourier transform, the frequency of the electric power was calculated, and then, suing interpol...A new accurate calculation method of electric power harmonic parameters was presented. Based on the delay time theorem of Fourier transform, the frequency of the electric power was calculated, and then, suing interpolation in the frequency domain of the windows, the parameters （amplitude and phase） of each harmonic frequency signals were calculated accurately. In the paper, the effect of the delay time and the windows on the electric power harmonic calculation accuracy was analysed. The digital simulation and the physical measurement tests show that the proposed method is effective and has more advantages than other methods which are based on multipoint interpolation especially in calculation time cost; therefore, it is very suitable to be used in the single chip DSP micro-processor.展开更多
This paper presents a wavelet neural network (WNN) model combining wavelet transform and artificial neural networks for short term load forecast (STLF). Both historical load and temperature data having important impac...This paper presents a wavelet neural network (WNN) model combining wavelet transform and artificial neural networks for short term load forecast (STLF). Both historical load and temperature data having important impacts on load level were used in the proposed forecasting model. The model used the three-layer feed forward network trained by the error back-propagation algorithm. To enhance the forecast- ing accuracy by neural networks, wavelet multi-resolution analysis method was introduced to pre-process these data and reconstruct the predicted output. The proposed model has been evaluated with actual data of electricity load and temperature of Hunan Province. The simulation results show that the model is capable of providing a reasonable forecasting accuracy in STLF.展开更多
We study a minimal extension of the standard model by introducing three right-handed neutrinos and a new scotogenic scalar doublet,in which the mass splittings between neutral and charged components are responsible fo...We study a minimal extension of the standard model by introducing three right-handed neutrinos and a new scotogenic scalar doublet,in which the mass splittings between neutral and charged components are responsible for the W-boson mass newly measured by the CDF Collaboration.This model can not only generate non-vanishing Majorana neutrino masses via the interaction of right-handed neutrinos and scotogenic scalars,but also explain the Universe’s missing matter in the form of FIMP dark matter.We also study the influence of the mass splitting on the first order electroweak phase transition,and find that it can further enhance the transition strength and thus induce gravitational waves during the phase transition,which may be detected in the forthcoming detectors such as U-DECIGO.展开更多
基金Project(ThEP-60-PIP-WU3)supported by the Thailand Center of Excellence in Physics。
文摘Implementation of manganese–bismuth(MnBi)alloys as high-performance permanent magnets is a challenge for physicists and engineers because the ferromagnetic low-temperature phase(LTP)is not exclusively obtained.In this work,melting powered by four commercial magnetrons of 2000–2500 W in a microwave furnace is demonstrated as a new route to alloy MnBi.Under an argon atmosphere,microwave heating transferred to pieces of broken Bi ingots and Mn flakes for 2 h gave rise to products of inhomogeneous composition and morphology.Scanning electron micrographs were classified into three regions according to morphology and elemental composition.Cubic-like clusters characterized as Mn precipitated over light solidified Bi-rich regions,and the MnBi phase was formed in homogeneous regions with a balanced composition between Mn and Bi.A ferromagnetic hysteresis loop was obtained in the ground powder with a coercivity of 40 kA/m.Subsequent annealing at 553 K under a pressure of 414 kPa for 12 h enhanced the MnBi phase with extended regions of balanced composition.It follows that the coercivity was increased to 60 kA/m.However,remanent magnetization was slightly reduced.This MnBi alloyed by microwave radiation can be further used in rare-earth-free magnets.
文摘A new accurate calculation method of electric power harmonic parameters was presented. Based on the delay time theorem of Fourier transform, the frequency of the electric power was calculated, and then, suing interpolation in the frequency domain of the windows, the parameters （amplitude and phase） of each harmonic frequency signals were calculated accurately. In the paper, the effect of the delay time and the windows on the electric power harmonic calculation accuracy was analysed. The digital simulation and the physical measurement tests show that the proposed method is effective and has more advantages than other methods which are based on multipoint interpolation especially in calculation time cost; therefore, it is very suitable to be used in the single chip DSP micro-processor.
文摘This paper presents a wavelet neural network (WNN) model combining wavelet transform and artificial neural networks for short term load forecast (STLF). Both historical load and temperature data having important impacts on load level were used in the proposed forecasting model. The model used the three-layer feed forward network trained by the error back-propagation algorithm. To enhance the forecast- ing accuracy by neural networks, wavelet multi-resolution analysis method was introduced to pre-process these data and reconstruct the predicted output. The proposed model has been evaluated with actual data of electricity load and temperature of Hunan Province. The simulation results show that the model is capable of providing a reasonable forecasting accuracy in STLF.
基金supported by the National Natural Science Foundation of China(11805161,12005180,and 11975195)the Natural Science Foundation of Shandong Province(ZR2020QA083 and ZR2019JQ04)the Project of Shandong Province Higher Educational Science and Technology Program(2019KJJ007)。
文摘We study a minimal extension of the standard model by introducing three right-handed neutrinos and a new scotogenic scalar doublet,in which the mass splittings between neutral and charged components are responsible for the W-boson mass newly measured by the CDF Collaboration.This model can not only generate non-vanishing Majorana neutrino masses via the interaction of right-handed neutrinos and scotogenic scalars,but also explain the Universe’s missing matter in the form of FIMP dark matter.We also study the influence of the mass splitting on the first order electroweak phase transition,and find that it can further enhance the transition strength and thus induce gravitational waves during the phase transition,which may be detected in the forthcoming detectors such as U-DECIGO.
