The line side winding is under the fundamental frequency AC voltage, while the valve side winding contains not only fundamental AC voltage component, but also the DC voltage component, fundamental AC voltage component...The line side winding is under the fundamental frequency AC voltage, while the valve side winding contains not only fundamental AC voltage component, but also the DC voltage component, fundamental AC voltage component, and higher harmonic voltage components when the converter transformer is at its normal operating condition, and the electric field of converter transformer is a non-sinusoidal steady one. To analyze the non-sinusoidal steady electric field containing the DC component, fundamental AC and higher harmonic components, the voltage spectrum of the valve winding in a ±500 kV converter transformer is firstly analyzed, and the non-sinusoidal periodic steady electric field is obtained by the fast discrete Fourier transform. Different resistivity of the oil and oil-immersed paper is adopted to simulate the aging of oil paper insulation at operation, and get the non-sinusoidal steady electric field.展开更多
Based on the idea that a large number of charged particles can be generated by a high-frequency alternating current(AC)dielectric barrier discharge(DBD),and charged particles can be accelerated directionally by a dire...Based on the idea that a large number of charged particles can be generated by a high-frequency alternating current(AC)dielectric barrier discharge(DBD),and charged particles can be accelerated directionally by a direct current(DC)electric field,a new type of ionic wind formation method is proposed in this paper.To this end,a carbon fiber spiral electrode serves as the generation electrode and a metal rod electrode as the collection electrode,with AC and DC potentials applied respectively to the generation electrode and the collection electrode to form an AC-DC coupled electric field.Under the action of the coupled electric field,a dielectric barrier discharge is formed on the carbon fiber spiral electrode,and the electrons generated by the discharge move from the generation electrode to the collection electrode in the opposite direction of the electric field vectors.During the movement,energy is transferred to the gas molecules by their colliding with neutral gas molecules,thereby forming a directional gas stream movement,i.e.ionic wind.In the research process,it is verified through electric field simulation analysis and discharge experiment that this method can effectively increase the number of charged particles in the discharge process,and the velocity of the ionic wind is nearly doubled.On this basis,the addition of a third electrode forms a distinct discharge region and an electron acceleration region,which further increases its velocity.The experimental result shows that the ionic wind speed reaches up to 2.98 m s^?1.Thanks to the ability of the electrode structure to generate an atmospheric pressure DBD plasma and form an ionic wind,we can create a noise-free air purification device without resorting to a fan,with this device having good application prospects in the field of air purification.展开更多
The electron structure and optical properties of C-TiO_(2)(001)surface under external electric field were studied by DFT method.After carbon doping,a new impurity level is introduced in the bandgap region of TiO_(2)(0...The electron structure and optical properties of C-TiO_(2)(001)surface under external electric field were studied by DFT method.After carbon doping,a new impurity level is introduced in the bandgap region of TiO_(2)(001)surface,and leads to the decrease of band gap,contributing to the shift of optical absorption to the visible region.When external electric field is applied across the C-TiO_(2)(001)surface,the band gap is further reduced with the increase of the electric field intensity from 0.1 eV to 0.5 eV.The electric field over 0.5 eV induces the electronic polarization.The spin-up bands show a gap,while spin-down electrons correspond to a metallic state.The energy gap of spin-up band decreases with increasing the electric field from 0.7 eV to 1.0 eV.The optical absorption of C-TiO_(2)(001)shifts to long wavelength compared with pure TiO_(2)(001).The electric filed make the optical absorption red-shift further,and the shift increases with an increase of the electric field,especially in the range of 0.7 eV-1.0 eV.The results show that the combined effect of carbon doping and electric field can enhance the photocatalytic activity of TiO_(2)(001)surface in visible region.展开更多
为了探讨脉冲电场(PEF)和X射线联合照射对小鼠雄性生殖和造血器官的复合效应,将74只成年雄性昆明种小鼠随机分成4组,即对照组、PEF组、X射线组以及PEF+X射线复合组。将PEF辐照参数设定为电场强度1 k V/m和重复频率10 k Hz。动物每天接受...为了探讨脉冲电场(PEF)和X射线联合照射对小鼠雄性生殖和造血器官的复合效应,将74只成年雄性昆明种小鼠随机分成4组,即对照组、PEF组、X射线组以及PEF+X射线复合组。将PEF辐照参数设定为电场强度1 k V/m和重复频率10 k Hz。动物每天接受PEF辐照1次,每次辐照时间为10 s,连续辐照3 d。PEF辐照结束24 h后复合组动物接受X射线全身照射,吸收剂量为7.0 Gy,吸收剂量率为1.1 Gy/min。照射完毕,观察动物体质量、外周血常规指标,睾丸、附睾、脾脏和胸腺脏器系数及睾丸形态结构,脾结节计数,动物15 d存活率。研究结果表明:与对照组相比,PEF组动物体质量、外周血常规指标、睾丸等脏器系数变化不显著,X射线组和复合组动物体质量明显降低,白细胞、淋巴细胞、血小板数量明显减少,胸腺和脾脏系数明显降低,睾丸组织结构损伤明显。与X射线组相比,复合组动物体质量、血液常规指标和脾结节数目变化不显著,但睾丸组织病理损伤明显减轻,动物15 d存活率有增高趋势。可得结论:单独脉冲电场对小鼠雄性生殖器官和造血器官无明显影响,并且对X射线引起的造血损伤无复合效应,但对X射线造成的睾丸组织损伤具有一定程度的保护作用。展开更多
文摘The line side winding is under the fundamental frequency AC voltage, while the valve side winding contains not only fundamental AC voltage component, but also the DC voltage component, fundamental AC voltage component, and higher harmonic voltage components when the converter transformer is at its normal operating condition, and the electric field of converter transformer is a non-sinusoidal steady one. To analyze the non-sinusoidal steady electric field containing the DC component, fundamental AC and higher harmonic components, the voltage spectrum of the valve winding in a ±500 kV converter transformer is firstly analyzed, and the non-sinusoidal periodic steady electric field is obtained by the fast discrete Fourier transform. Different resistivity of the oil and oil-immersed paper is adopted to simulate the aging of oil paper insulation at operation, and get the non-sinusoidal steady electric field.
基金National Natural Science Foundation of China(No.51577011).
文摘Based on the idea that a large number of charged particles can be generated by a high-frequency alternating current(AC)dielectric barrier discharge(DBD),and charged particles can be accelerated directionally by a direct current(DC)electric field,a new type of ionic wind formation method is proposed in this paper.To this end,a carbon fiber spiral electrode serves as the generation electrode and a metal rod electrode as the collection electrode,with AC and DC potentials applied respectively to the generation electrode and the collection electrode to form an AC-DC coupled electric field.Under the action of the coupled electric field,a dielectric barrier discharge is formed on the carbon fiber spiral electrode,and the electrons generated by the discharge move from the generation electrode to the collection electrode in the opposite direction of the electric field vectors.During the movement,energy is transferred to the gas molecules by their colliding with neutral gas molecules,thereby forming a directional gas stream movement,i.e.ionic wind.In the research process,it is verified through electric field simulation analysis and discharge experiment that this method can effectively increase the number of charged particles in the discharge process,and the velocity of the ionic wind is nearly doubled.On this basis,the addition of a third electrode forms a distinct discharge region and an electron acceleration region,which further increases its velocity.The experimental result shows that the ionic wind speed reaches up to 2.98 m s^?1.Thanks to the ability of the electrode structure to generate an atmospheric pressure DBD plasma and form an ionic wind,we can create a noise-free air purification device without resorting to a fan,with this device having good application prospects in the field of air purification.
基金This research was supported by Guangxi Natural Science Foundation(No.2017GXNSFAA198247).
文摘The electron structure and optical properties of C-TiO_(2)(001)surface under external electric field were studied by DFT method.After carbon doping,a new impurity level is introduced in the bandgap region of TiO_(2)(001)surface,and leads to the decrease of band gap,contributing to the shift of optical absorption to the visible region.When external electric field is applied across the C-TiO_(2)(001)surface,the band gap is further reduced with the increase of the electric field intensity from 0.1 eV to 0.5 eV.The electric field over 0.5 eV induces the electronic polarization.The spin-up bands show a gap,while spin-down electrons correspond to a metallic state.The energy gap of spin-up band decreases with increasing the electric field from 0.7 eV to 1.0 eV.The optical absorption of C-TiO_(2)(001)shifts to long wavelength compared with pure TiO_(2)(001).The electric filed make the optical absorption red-shift further,and the shift increases with an increase of the electric field,especially in the range of 0.7 eV-1.0 eV.The results show that the combined effect of carbon doping and electric field can enhance the photocatalytic activity of TiO_(2)(001)surface in visible region.
