This paper proposes a parameters extraction procedure based on the integrated evaluation of static and dynamic characteristics. The existing procedure available for various model is based on formal optimization with direct search, but it yields static characteristics with low accuracy, and its computation cost is high. The proposed procedure helps solve these problems since static characteristic evaluation is added to an objective function and the search range is narrowed. Validation with the simulation results of parameters optimization for a pin diode model demonstrates that the proposed procedure has high accuracy and low computation cost.
Recognizing characters in scene images suffering from perspective distortion is a challenge. Although there are some methods to overcome this difficulty, they are time-consuming. In this paper, we propose a set of affine invariant features and a new recognition scheme called “progressive removing” that can help reduce the processing time. Progressive removing gradually removes less feasible categories and skew angles by using multiple classifiers. We observed that progressive removing and the use of the affine invariant features reduced the processing time by about 60% in comparison to a trivial one without decreasing the recognition rate.
This paper proposes a new topology for a current balancer with half-bridge inverters in single-phase three-wire distribution systems with a three-leg inverter. Two half-bridge inverters are connected to the sources. The midpoint of two capacitors on the DC-side is connected to a neutral line. The two half-bridge inverters perform a current balancer for single-phase three-wire distribution systems by exchanging the active and reactive power on the each feeder through the two DC-capacitors. The third-leg performs a DC-capacitor-voltage balancer for the two DC-capacitors connected to the half-bridge inverters. Thus, balanced source voltages and currents are obtained on the secondary-side on the pole-mounted distribution transformer with balanced DC-capacitor voltages. The basic principle of the proposed current balancer is discussed in detail, and then, confirmed by digital computer simulation using PSIM software. A prototype experimental model is constructed and tested. Experimental results show that balanced source voltages and currents are obtained on the secondary-side on the pole-mounted distribution transformer with balanced DC-capacitor voltages.
Recently, there have been many brutal crimes. Therefore, surveillance cameras have been installed at various places. This has led to the volume of image records being very large. Therefore it is necessary to develop an automatic method for checking suspicious persons. It is difficult to extract parts containing people from an image sequence. A lot of methods for extracting people regions have been developed. However the conventional methods need many images or precise background images. In this paper, we propose a method to extract people regions from an image by applying the Hough Transform twice. In the first step, people regions are obtained by the first Hough Transform of direction cords. The first Hough Transform pertains to connecting of the outline of the people regions and extracts the pixels of the people regions. In the next step, people regions are decided by the second generalized Hough Transform which pertains to the shapes of heads and shoulders. Some experimental results that indicate the effectiveness of the proposed method are also reported.
Car navigation systems play a prominent role in road traffic safety and traffic regulation. However, it is necessary to improve the route guidance of car navigation systems so that accurately and quickly recognize small differences in location. Thus, to increase the ease of understanding and safety of car-navi systems, navigation systems based on augmented reality have been proposed for providing guidance at road intersections. We are currently developing a car navigation system based on augmented reality, called AR-Navi. We investigated designs for the display of road intersection guidance that can be easily understood even when limited information is available and proposed a “best shot” display method that does not use moving images. In addition, we implemented a prototype system that includes these methods and conducted driving experiments on public roads to evaluate the ease of understanding and safety of AR-Navi. Using the evaluation results, we confirmed that the ease of understanding and safety is similar in the case of AR-Navi and CG-Navi. We also clarified the characteristics of AR-Navi.
This paper reports the results of the miniaturization design of a permanent-magnet synchronous motor, for which an optimal design technique based on thermomagnetic field coupling analysis is used. We derived the optimal solutions for various motor flatness ratios and determined the relationship between the motor size and the flatness ratio. For motors with different flatness ratios, we calculated the speed-torque characteristics by considering the voltage, temperature rise, and demagnetization limits and compared them. Moreover, we manufactured and tested the smallest designed motor. The measured temperature rises demonstrated the high accuracy of the proposed miniaturization design.
Owing to the need for high-speed, high-density, and comfortable rail transport, an automatic train control (ATC) system in which digital signal technologies are used to achieve wayside-to-onboard data communication via rails has been developed. However, it is not easy to apply digital signals to existing revenue lines, which already use analog signals, because the current frequency allocation cannot be changed due to the track circuit arrangement and interoperability situations. Meanwhile, existing analog signals that are transmitted contain information in the form of amplitude-modulation frequencies, which are envelope components of signal wave. Unless the modulation frequencies are varied, digital modulation signals such as phase-modulated signals or frequency-modulated signals can be used as carrier wave. Combined digital/analog signals consisting of digital modulation signals that are amplitude-modulated using existing signals frequencies, enable digital signals to be used in the revenue lines with analog ATC. We studied combined digital/analog signals and found that they satisfy the requirements of both analog and digital signals. Consequently, we conclude that signal transmission to existing ATC systems becomes possible by using an MSK (minimum shift keying) wave as a carrier wave of digital/analog signals and the modulation amplitude of carrier wave identical to that of an existing wave.
The tower building categories used in the energy breakdown are Electric lighting, the heating, ventilating, and air conditioning (HVAC) auxiliary and Office equipment. The HVAC system has the greatest energy saving potential as it is the major energy consumer. It consumes approximately 64 percent of the total building energy. A good HVAC in buildings helps reduce energy use and maintain occupant comfort. To this end, there are many systems and equipment conditions to observe HVAC systems. This paper critically examines indoor climate control technologies to reduce the HVAC system energy. The autonomous variable air volume diffusers are interconnected to simulate the responses of the system. The constrained optimal control problem is formulated and solved for increased operative temperature. The experiment results show that by increasing the operative temperature from 25°C to 27°C, the electrical energy can be saved by 11.64 percent. The proposed method feeds back the output air to input boundary conditions of the same human thermal sensation even though the air velocity distributions in the sections are different from each other. The experiment results also show that the proposed method can maintain the PMV values in an interval of -0.5 to +0.5 at an acceptable air velocity range.
This paper presents a performance improvement of trajectory tracking for the fast-response and high-precision positioning by a sequential adaptive compensation for disturbance. A mathematical disturbance model formulated and parameterized by an iterative learning process can estimate the actual disturbance, and the model can be sequentially adapted by a recursive least-squares method so that it shows the adaptive property against disturbance variations. The proposed positioning control approach involving disturbance modeling and compensation has been verified by experiments using a linear motor-driven table system.
Electric double-layer capacitors (EDLCs) offer several advantages over traditional batteries, such as long cycle life, high power capability, good low-temperature performance, etc. However, their major drawbacks, such as low specific energy and large voltage variation due to charge/discharge cycling, necessitate the use of high-efficiency power conversion electronics that can be used to efficiently discharge EDLCs and thus completely utilize the precious stored energy. In this study, we propose a novel discharger for EDLCs; this discharger uses cascaded switched capacitor converters (SCCs) and selectable intermediate taps. Although the voltage conversion ratio of SCCs is fixed, the load voltage can be maintained within a desired voltage range by the selectable intermediate taps. The circuit configuration, operating principle, and procedure for designing SCCs and selectable intermediate taps are presented. Experimental tests were performed using an EDLC module and a 200W prototype of the discharger. The obtained results showed that the 60V EDLC could be discharged to 30V with an average efficiency of 96% when the load voltage was maintained within the range 30-40V.
This paper presents a new high power factor control method for a single-to-three-phase power converter without an electrolytic capacitor. The circuit used in the method consists of a single-phase rectifier, a small film capacitor at DC-link, a voltage-source three-phase inverter, and an IPM motor. The inverter regulates both the velocity of the IPM motor and input current waveform. In order to obtain a power factor of unity, we propose a new control method that regulates the inverter output power. The inverter output power controller is placed between the speed controller and the q-axis current controller. The inverter power is regulated by a PI and repetitive controller. When repetitive control is applied to the inverter power controller, the phase delay of the inverter power controller is quite small. The superior performance of the proposed method is demonstrated by experimental results.
A 12-pulse phase-controlled rectifier consists of two sets of 6-pulse rectifiers. It is found that harmonic distortion of the input current is minimized if dc currents of the two rectifiers are in a boundary between continuous and discontinuous conduction modes. In order to realize the boundary mode operation under any load conditions an auxiliary voltage supply (AVS) is introduced. The AVS is required a bi-directional power flow but its handled net power is quite small. Capacity of AVS is less than 10% of rated rectifier output. A simple AVS arrangement is proposed and the usefulness is verified by simulation and experimental results.
Recently, the Peltier device has been attracting attention as a haptic device that can transfer heat, because it has relatively fast response characteristics among thermal devices. To transmit the thermal sensation, temperature control is considered to be important. However, it is difficult to design a controller because of factors such as parameter variations, nonlinear characteristics of the device, and heat that flows from an external object. Moreover, it is preferable that the tracking performance and disturbance suppression characteristics be designed independently. To address these factors, this paper proposes a heat disturbance observer, which is constructed by using the disturbance observer commonly used in the field of motion control. When the observer is used, the thermal system becomes robust to the above-mentioned factors. In addition, it is possible to design the tracking performance independent of the disturbance suppression characteristics. The validity of the proposal is confirmed by experimental results.
Single-switch bridge leg with a snubber energy recovery feature is studied for buck rectifier applications. To recover the snubber energy, two snubber capacitors are arranged across an active power device. An example of a single-phase rectifier applying a proposed bridge leg is implemented to investigate the operation. The experimental results under the sinusoidal pulse-width modulation confirm that the rectifier can recover the snubber energy and the input current is almost wave-shaped sinusoidally with a near-unity power factor.