The electromotive force （e.m.f.） of solid oxide fuel cells using biomass produced gas （BPG） as the fuels is calculated at 700-1,200 K using an in-house computer program, based on thermodynamic equilibrium analysis...The electromotive force （e.m.f.） of solid oxide fuel cells using biomass produced gas （BPG） as the fuels is calculated at 700-1,200 K using an in-house computer program, based on thermodynamic equilibrium analysis. Tour program also predicts the concentration of oxygen in the fuel chamber as well as the concentration of equilibrium species such as H2, CO, CO2 and CH4. Compared with using hydrogen as a fuel, the e.m.f. for cells using BPG as the fuels is relative low and strongly influenced by carbon deposition. To remove carbon deposition, the optimum amount of H2O to add is determined at various operating temperatures. Further the e.m.f, for cells based on yttria stabilized zirconia and doped ceria as electrolytes are compared. The study reveals that when using BPG as fuel, the depression of e.m.f, for a SOFC using doped ceria as electrolyte is relatively small when compared with that using Yttria stabilized zirconia.展开更多
When one end of an air-dry igneous rock block was uniaxially loaded in laboratory, there appeared an electromotive force that made electric currents flow from the stressed volume to the unstressed volume. Quartz-free ...When one end of an air-dry igneous rock block was uniaxially loaded in laboratory, there appeared an electromotive force that made electric currents flow from the stressed volume to the unstressed volume. Quartz-free rocks such as gabbro also generated this force, stronger than quartz-bearing rocks such as granite. This indicates that the piezoelectric effect of quartz and the electrokinetic effect of pore water do not make a large contribution toward generating the electromotive force. We focus on peroxy bond that is one of the abundant lattice defects in igneous rock-forming minerals. When mechanical loading deforms the lattice structure around this defect and breaks its bond, its energy levels change and act like an accepter. As an electron is trapped at this defect from a neighbor 02- site, a positive hole is activated there. They attempt to diffuse toward the unstressed volume through the valence band and are simultaneously affected by the attractive electric force with the electrons trapped in peroxy bonds. This leads to a polarization in the stressed volume and the generation of electromotive force between the stressed and unstressed volumes. Similar electromotive force may be generated in the Earth＇s crust where inhomogeneous stress/strain is changing.展开更多
The principles of electromagnetic induction are applied in many devices and systems, including induction cookers, transformers and wireless energy transfer;however, few data are available on resonance in the electromo...The principles of electromagnetic induction are applied in many devices and systems, including induction cookers, transformers and wireless energy transfer;however, few data are available on resonance in the electromotive force (EMF) of electromagnetic induction. We studied electromagnetic induction between two circular coils of wire: one is the source coil and the other is the pickup (or induction) coil. The measured EMF versus frequency graphs reveals the existence of a resonance/anti-resonance in the EMF of electromagnetic induction through free space. We found that it is possible to control the system’s resonance and anti-resonance frequencies. In some devices, a desired resonance or antiresonance frequency is achieved by varying the size of the resonator. Here, by contrast, our experimental results show that the system’s resonance and anti-resonance frequencies can be adjusted by varying the distance between the two coils or the number of turns of the induction coil.展开更多
Macrosegregations and microstructures of Al-7%Si alloy solidified under complex of fects of magnetic field and centrifugal forces are studied by means of a set of selfdesigned electromagnetic centrifugal casting (EMC...Macrosegregations and microstructures of Al-7%Si alloy solidified under complex of fects of magnetic field and centrifugal forces are studied by means of a set of selfdesigned electromagnetic centrifugal casting (EMCC) device. It is shown that electromagnetic field (EMF) has an important effect on the macrosegregation of centrifugal casting specimen of Al-7%Si alloy in two respects: one is that there exists always a kind of convection in the liquid in front of the S/L interface caused by effect ofthe electromagnetic force; the other is that different atomic clusters of solidparticles with different physical characteristics are subjected to quite different electromagnetic (Lorentz) force. Therefore, their movements get changed. In addition, the formation process of a complex band structure consisting of primary α-Al dendrites and (α-Al+β-Si) eutectics in hypoeutectic Al-Si alloys during EMCC and the effect of EMF are discussed.展开更多
讨论了电动汽车镍氢动力电池荷电状态(State of Charge,简称SOC)的估计方法。提出用电动势(EMF)等效电路模型法来估计电池的SOC。研究确定了EMF与SOC之间的关系,并通过电路分析,计算得出电池EMF与端电压之间的关系,最终建立了端电压与SO...讨论了电动汽车镍氢动力电池荷电状态(State of Charge,简称SOC)的估计方法。提出用电动势(EMF)等效电路模型法来估计电池的SOC。研究确定了EMF与SOC之间的关系,并通过电路分析,计算得出电池EMF与端电压之间的关系,最终建立了端电压与SOC关系。通过实测数据并利用模型估计数据的对比得出,SOC的误差在混合动力汽车的允许误差范围内。该方法在车辆停车和行驶时均适用。展开更多
提出一种改进型反电动势谐波自适应补偿的PMSG无位置传感器控制方法,该方法在滑模观测器SMO(sliding model observer)的基础上引入自适应广义二阶积分器SOGI(second order generalized integrator),减小了反电动势观测中谐波对转子位置...提出一种改进型反电动势谐波自适应补偿的PMSG无位置传感器控制方法,该方法在滑模观测器SMO(sliding model observer)的基础上引入自适应广义二阶积分器SOGI(second order generalized integrator),减小了反电动势观测中谐波对转子位置的影响,提高了转子位置估计的准确性。由于电机参数的变化和变换器的非线性,在无位置传感器控制算法中含有大量的5、7、11次等低次谐波。使用自适应SOGI取代低通滤波器,对基频信号进行提取,一方面减小了低频谐波含量,从而减小了由低频谐波引起的转子位置估计偏差,同时消除了由滤波延时引起的相位偏差;另一方面提高了系统的跟踪性能,使得相位误差收敛于0。最后,通过仿真和实验验证了所提方法的正确性和可行性。展开更多
基金V. ACKN0WLEDGMENT This work was supported by the National Natural Science Foundation of China （No.50372066 and No.50332040）.
文摘The electromotive force （e.m.f.） of solid oxide fuel cells using biomass produced gas （BPG） as the fuels is calculated at 700-1,200 K using an in-house computer program, based on thermodynamic equilibrium analysis. Tour program also predicts the concentration of oxygen in the fuel chamber as well as the concentration of equilibrium species such as H2, CO, CO2 and CH4. Compared with using hydrogen as a fuel, the e.m.f. for cells using BPG as the fuels is relative low and strongly influenced by carbon deposition. To remove carbon deposition, the optimum amount of H2O to add is determined at various operating temperatures. Further the e.m.f, for cells based on yttria stabilized zirconia and doped ceria as electrolytes are compared. The study reveals that when using BPG as fuel, the depression of e.m.f, for a SOFC using doped ceria as electrolyte is relatively small when compared with that using Yttria stabilized zirconia.
基金partially supported by"Observation and Research Program for Prediction of Earthquakes and Volcanic Eruptions"of the Ministry of Education,Culture,Sports,Science and Technology of Japan,"FY2010 Research Incentive Assistance Program"of Educational System General Research Organization,Tokai University"Individual Research Projects"of Institute of Oceanic Development of Science and Technology,Tokai University
文摘When one end of an air-dry igneous rock block was uniaxially loaded in laboratory, there appeared an electromotive force that made electric currents flow from the stressed volume to the unstressed volume. Quartz-free rocks such as gabbro also generated this force, stronger than quartz-bearing rocks such as granite. This indicates that the piezoelectric effect of quartz and the electrokinetic effect of pore water do not make a large contribution toward generating the electromotive force. We focus on peroxy bond that is one of the abundant lattice defects in igneous rock-forming minerals. When mechanical loading deforms the lattice structure around this defect and breaks its bond, its energy levels change and act like an accepter. As an electron is trapped at this defect from a neighbor 02- site, a positive hole is activated there. They attempt to diffuse toward the unstressed volume through the valence band and are simultaneously affected by the attractive electric force with the electrons trapped in peroxy bonds. This leads to a polarization in the stressed volume and the generation of electromotive force between the stressed and unstressed volumes. Similar electromotive force may be generated in the Earth＇s crust where inhomogeneous stress/strain is changing.
文摘The principles of electromagnetic induction are applied in many devices and systems, including induction cookers, transformers and wireless energy transfer;however, few data are available on resonance in the electromotive force (EMF) of electromagnetic induction. We studied electromagnetic induction between two circular coils of wire: one is the source coil and the other is the pickup (or induction) coil. The measured EMF versus frequency graphs reveals the existence of a resonance/anti-resonance in the EMF of electromagnetic induction through free space. We found that it is possible to control the system’s resonance and anti-resonance frequencies. In some devices, a desired resonance or antiresonance frequency is achieved by varying the size of the resonator. Here, by contrast, our experimental results show that the system’s resonance and anti-resonance frequencies can be adjusted by varying the distance between the two coils or the number of turns of the induction coil.
文摘Macrosegregations and microstructures of Al-7%Si alloy solidified under complex of fects of magnetic field and centrifugal forces are studied by means of a set of selfdesigned electromagnetic centrifugal casting (EMCC) device. It is shown that electromagnetic field (EMF) has an important effect on the macrosegregation of centrifugal casting specimen of Al-7%Si alloy in two respects: one is that there exists always a kind of convection in the liquid in front of the S/L interface caused by effect ofthe electromagnetic force; the other is that different atomic clusters of solidparticles with different physical characteristics are subjected to quite different electromagnetic (Lorentz) force. Therefore, their movements get changed. In addition, the formation process of a complex band structure consisting of primary α-Al dendrites and (α-Al+β-Si) eutectics in hypoeutectic Al-Si alloys during EMCC and the effect of EMF are discussed.
文摘讨论了电动汽车镍氢动力电池荷电状态(State of Charge,简称SOC)的估计方法。提出用电动势(EMF)等效电路模型法来估计电池的SOC。研究确定了EMF与SOC之间的关系,并通过电路分析,计算得出电池EMF与端电压之间的关系,最终建立了端电压与SOC关系。通过实测数据并利用模型估计数据的对比得出,SOC的误差在混合动力汽车的允许误差范围内。该方法在车辆停车和行驶时均适用。
文摘提出一种改进型反电动势谐波自适应补偿的PMSG无位置传感器控制方法,该方法在滑模观测器SMO(sliding model observer)的基础上引入自适应广义二阶积分器SOGI(second order generalized integrator),减小了反电动势观测中谐波对转子位置的影响,提高了转子位置估计的准确性。由于电机参数的变化和变换器的非线性,在无位置传感器控制算法中含有大量的5、7、11次等低次谐波。使用自适应SOGI取代低通滤波器,对基频信号进行提取,一方面减小了低频谐波含量,从而减小了由低频谐波引起的转子位置估计偏差,同时消除了由滤波延时引起的相位偏差;另一方面提高了系统的跟踪性能,使得相位误差收敛于0。最后,通过仿真和实验验证了所提方法的正确性和可行性。
