A vehicle stopping method using an electric brake until a traction motor is stopped is studied. At the moment of vehicle stop, electric brake is changed to control mode where torque is reduced at a low speed. Gradient...A vehicle stopping method using an electric brake until a traction motor is stopped is studied. At the moment of vehicle stop, electric brake is changed to control mode where torque is reduced at a low speed. Gradient is controlled by estimating the load torque of motor, thereby traction motor is not rotated after stop. In addition, coasting operation and brake test are performed from normal-opposite operation and start using a small-scale model comprising the inertial load equipment and the power converter. Further, traction motor is made to be equipped with a suspension torque. Pure electric braking that makes traction motor stop by an air brake at the time of stop is also implemented. Constant torque range and constant power range are expanded during braking so that braking force is secured with the electric brakes even in high speed region. Therefore, vehicle reduction effect can be expected by reducing parts related with an air brake which is not used frequently by using a pure electric brake in the M car in wide speed region. Further, maintenance of brake system can be reduced. Besides, ride comfort of passenger in the electric rail car, energy efficiency improvement, and noise reduction effect can be additionally expected. Further, an improved brake method that uses only an electric brake till motor stop is proposed by comparing those in the blending brake that uses an air brake while reducing brake torque at vehicle stop.展开更多
PSPICE model driven by an electric equivalent circuit of a piezoelectric circuit is presented. In order to confirm this model to be effective, an independent model of cold cathode fluorescent lamp(CCFL) driving circui...PSPICE model driven by an electric equivalent circuit of a piezoelectric circuit is presented. In order to confirm this model to be effective, an independent model of cold cathode fluorescent lamp(CCFL) driving circuit is used to conduct simulations, leading to a precise modeling. A library is configured through modeling and its accuracy is verified through simulations for widely used and representative lamps such as CCFL, fluorescent lamps, HID lamps, and electrodeless fluorescent lamps. On the basis of experiments, a lamp simulation is also performed using PSPICE, which allows us to take advantage of the lamp library easily. Also, PSPICE model driven by an electric equivalent circuit of a piezoelectric transformer is presented. In order to confirm this model to be effective, an independent model of CCFL driving circuit is used to conduct simulations, leading to a precise modeling. In addition, a new type of electronic ballast is proposed, which allows 35 W-class(T5-class) fluorescent lamp to work. This system is built by a rectifier which has improved power factor and half-bridge series resonant inverter. Also, with size of 27.5 mm high, 27.5 mm wide and 2.5 mm thick, the produced piezoelectric transformer has a high step-up ratio, through which it is possible for the electric ballast circuit to be lighter, smaller and more efficient. After the produced ballast is used to drive the fluorescent lamp for 25 min, it yields 0.95 in power factor correction, 86% in efficiency, 35.07 W in output voltage and 20.5 °C in temperature increase while meeting the characteristics of the 35 W-class fluorescent lamp.展开更多
In this study, to fabricate dual-pore scaffolds with interconnected pores, Non-solvent Induced Phase Separation （NIPS） and Wire-Network Molding （WNM） techniques were combined. First, a mold with uniform slits was ...In this study, to fabricate dual-pore scaffolds with interconnected pores, Non-solvent Induced Phase Separation （NIPS） and Wire-Network Molding （WNM） techniques were combined. First, a mold with uniform slits was prepared, and needles were inserted into the mold. Subsequently, polycaprolactone （PCL） pellets were dissolved in tetrahydrofuran （THF） at a specified ratio. The slurry was mixed using hot plate stirrer at 1200 rpm for 24 hours at 40 ~C. The PCL slurry was subsequently injected into the mold. Thereafter, to exchange the THF （solvent） with the ethanol （non-solvent）, the mold was soaked in an ethanol bath. After removing the mold from the ethanol bath, the needles were removed from the mold. Consequently, dual-pore scaffold with interconnected pores was obtained. The surface morphology of the fabricated scaffolds were observed using Scanning Electron Microscope （SEM）. Moreover, cell culture experiments were performed using the CCK-8 assay, and the characteristics of cells grown on the dual-pore scaffolds were assessed and were compared with the NIPS-based 3D plotting scaffold.展开更多
文摘A vehicle stopping method using an electric brake until a traction motor is stopped is studied. At the moment of vehicle stop, electric brake is changed to control mode where torque is reduced at a low speed. Gradient is controlled by estimating the load torque of motor, thereby traction motor is not rotated after stop. In addition, coasting operation and brake test are performed from normal-opposite operation and start using a small-scale model comprising the inertial load equipment and the power converter. Further, traction motor is made to be equipped with a suspension torque. Pure electric braking that makes traction motor stop by an air brake at the time of stop is also implemented. Constant torque range and constant power range are expanded during braking so that braking force is secured with the electric brakes even in high speed region. Therefore, vehicle reduction effect can be expected by reducing parts related with an air brake which is not used frequently by using a pure electric brake in the M car in wide speed region. Further, maintenance of brake system can be reduced. Besides, ride comfort of passenger in the electric rail car, energy efficiency improvement, and noise reduction effect can be additionally expected. Further, an improved brake method that uses only an electric brake till motor stop is proposed by comparing those in the blending brake that uses an air brake while reducing brake torque at vehicle stop.
文摘PSPICE model driven by an electric equivalent circuit of a piezoelectric circuit is presented. In order to confirm this model to be effective, an independent model of cold cathode fluorescent lamp(CCFL) driving circuit is used to conduct simulations, leading to a precise modeling. A library is configured through modeling and its accuracy is verified through simulations for widely used and representative lamps such as CCFL, fluorescent lamps, HID lamps, and electrodeless fluorescent lamps. On the basis of experiments, a lamp simulation is also performed using PSPICE, which allows us to take advantage of the lamp library easily. Also, PSPICE model driven by an electric equivalent circuit of a piezoelectric transformer is presented. In order to confirm this model to be effective, an independent model of CCFL driving circuit is used to conduct simulations, leading to a precise modeling. In addition, a new type of electronic ballast is proposed, which allows 35 W-class(T5-class) fluorescent lamp to work. This system is built by a rectifier which has improved power factor and half-bridge series resonant inverter. Also, with size of 27.5 mm high, 27.5 mm wide and 2.5 mm thick, the produced piezoelectric transformer has a high step-up ratio, through which it is possible for the electric ballast circuit to be lighter, smaller and more efficient. After the produced ballast is used to drive the fluorescent lamp for 25 min, it yields 0.95 in power factor correction, 86% in efficiency, 35.07 W in output voltage and 20.5 °C in temperature increase while meeting the characteristics of the 35 W-class fluorescent lamp.
文摘In this study, to fabricate dual-pore scaffolds with interconnected pores, Non-solvent Induced Phase Separation （NIPS） and Wire-Network Molding （WNM） techniques were combined. First, a mold with uniform slits was prepared, and needles were inserted into the mold. Subsequently, polycaprolactone （PCL） pellets were dissolved in tetrahydrofuran （THF） at a specified ratio. The slurry was mixed using hot plate stirrer at 1200 rpm for 24 hours at 40 ~C. The PCL slurry was subsequently injected into the mold. Thereafter, to exchange the THF （solvent） with the ethanol （non-solvent）, the mold was soaked in an ethanol bath. After removing the mold from the ethanol bath, the needles were removed from the mold. Consequently, dual-pore scaffold with interconnected pores was obtained. The surface morphology of the fabricated scaffolds were observed using Scanning Electron Microscope （SEM）. Moreover, cell culture experiments were performed using the CCK-8 assay, and the characteristics of cells grown on the dual-pore scaffolds were assessed and were compared with the NIPS-based 3D plotting scaffold.
