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In this paper, we propose a method to accurately calculate the turn-off switching loss. For that purpose, a simple analytical model is proposed in which the parasitic capacitances and stray inductances are integrated within the power module. Experiment confirmed that the turn-off loss analyzed by this model is correct.
We investigate geometries for efficient coupling of single ions to fiber-coupled light fields for applications in quantum sensing, quantum metrology, and quantum information processing. Specifically, we discuss the integration of fiber-tip microcavities into radio-frequency ion traps. The distortions of the trapping fields induced by the presence of the optical fibers are simulated for a range of...
We investigate the distortions of trapping potentials when integrating fiber-tip optical cavities into small ion traps. Trap depths, frequencies, and anharmonicity are investigated numerically for several geometries and the most stable traps are identified.
In many quantum information applications quantum bits (qubits) are stored in single trapped atoms or ions. In particular, single ions held in radiofrequency electromagnetic traps are preferred because of their long achievable decoherence time and record-breaking quantum gate fidelity [1]. However, for scalable quantum information processing many such stationary qubits need to be connected. A preferred...
MIB is a media recorder/player of sound and video handled with a gesture interface. The proposed technique allows users to capture and play audio-visual data by using gesture towards graphical bubbles. A graphical bubble, on which an image captured by a camera is mapped, is generated in real time when a user has captured an audio-visual datum. The captured datum is enclosed with the generated graphical...
Novel pixel structure with Stacked Deep Photodiode (SDP) has been newly developed for both high Near Infra-Red (NIR) sensitivity and high Modulation Transfer Function (MTF). SDP with 5.4µm pixel pitch has achieved Quantum Efficiency (QE) of 30% and MTF of 40% at Nyquist frequency at 850nm wavelength by stacking photodiode completely separated from neighboring pixels.
TIG arc welding is the high-quality joining technology. However, the current has to be small because the cathode melting should be prevented. In this case, the welding pool is shallow, then, the welding defect sometimes occurs. The pulsed TIG arc welding is often used in order to obtain the deep penetration of the welding pool. However, few report has reported the distribution of arc contaminated...
This paper investigates a listen before talk (LBT) algorithm to realize both collision avoidance with nodes of other wireless systems/operators and one-cell reuse operation among nodes of the same operator for long term evolution (LTE) based licensed-assisted access (LAA) in unlicensed spectrum. When LTE system is operated in unlicensed spectrum, implementation of a LBT algorithm is required to not...
In recent years, computer device operation by gaze input has become popular. Some of the advantages are that those devices can be operated without hand. People with disabilities, therefore, are able to operate computers. This is also suitable for elderly people for whom it is easier to use gaze input than mice. It is, however, difficult to point to a target steadily by using eye gaze as the input,...
This paper proposes a FRT (Fault ride through) method of a matrix converter under three-phase short voltage sag. The feature of the proposed method is to control grid reactive current and generator torque at the same time. In order to realize these capabilities, this paper describes a modulation method dividing a control period into 3 modes. The first mode is to turn off all switches and the second...
This paper proposes a control method of a matrix converter in a micro grid system to obtain stable islanded operation. The islanded operation using a matrix converter needs a voltage feedback control to assume the matrix converter as a constant voltage power supply for the load. On the other hand, the islanded operation also requires a generator current control with a feedback to determine provided...
Blood velocity estimation in the cardiac cavity has been useful to diagnose the heart function. In recent years, the two-dimensional (2D) blood velocity has been estimated by detecting echoes from blood cells obtained by high-frame-rate echocardiography with diverging ultrasound emission and parallel receive beamforming. However, the stability of estimated velocities in the transverse direction (perpendicular...
Image foreground object extraction is still challenging yet interesting topic in visual computing area. This paper proposes foreground extraction method based on one of the basic camera functions, focusing. A focus point and variation of blurs are extracted based on focusing, and these can be essential information to extract the foreground image. A focus point shows the rough position of the foreground,...
This paper proposes a Zero Voltage Switching (ZVS) method for an isolated DC to three-phase AC converter using an indirect matrix converter at the secondary side of the transformer. Phase-shift control is applied to the inverter at the primary side of the transformer, while Pulse Density Modulation (PDM) is employed to the indirect matrix converter at the secondary side. The inverter at the secondary...
This paper proposes a switching method and a LC design method in order to suppress the distortion of the input current which occurs in a high efficiency AC-AC converter. The proposed AC-AC converter which is used in online-type Uninterruptible Power Supplies (UPS) is constructed by a T-type three-level rectifier and a T-type three-level inverter. The switching loss of the proposed AC-AC converter...
This paper presents an isolated type of single-phase matrix converter topology for PHV/EV on-board battery chargers. The proposed converter is comprised of a full bridge inverter, a high frequency transformer and a matrix converter. Due to the lack of DC link bus in matrix converter, in order to suppress the power fluctuation, a power decoupling method which only employs a center-tapped high frequency...
This paper presents a controller design of an electric wheelchair for avoiding collision and downhill turning. The presented method for collision avoidance is based on the information from inexpensive distance sensors so that it may be widely used at low implementation cost. The presented method considers the nonholonomic constraints of a typical differential wheel drive system by employing the model...
This paper proposes an AC-AC converter, which consists of T-type three-level rectifier and inverter, for an on-line UPS. The switching loss of the proposed AC-AC converter is drastically reduced because the proposed converter is driven at a very low switching frequency which is six times of input side frequency. The T-type rectifier separates the maximum phase-voltage, medium phase-voltage and minimum...
This paper presents an isolated DC to single-phase AC converter using a matrix converter for HVDC (higher voltage direct current) power feeding system. The proposed converter comprises a full bridge inverter, a high frequency transformer and a matrix converter and does not use a bulky electrolytic capacitor. Then, in order to reduce a ripple component in a DC bus current caused by the single-phase...
The relationship between the complex blood flow inside the human heart and the cardiac pumping function has received attention in recent years. We previously proposed a method for high-frame-rate imaging of echoes from blood particles with diverging beam transmission in order to visualize the flow direction in the human heart. In the present study, the velocity vector estimator with speckle-tracking...
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