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Various techniques have been applied to the fabrication of duplicate dentures. In this new method, after scanning the cameo and intaglio surfaces of the complete denture using an intraoral scanner, the two images were superimposed on the interocclusal image. The linear gap between cameo and intaglio surfaces was filled using free downloadable CAD software. The superimposed image was subsequently used as data for fabricating the duplicate complete denture with a 3D printer. Using the intraoral scanner, duplication of complete dentures could be performed without needing any complicated processes, laboratory scanners, or advanced CAD software.

Japan’s universal healthcare insurance is facing economic challenges due to the advanced aging society, however, objective data of dental expenditure has never been introduced. This study aimed to identify the associated factors with dental expenditures using government-provided digitized insurance claims data and calculated the spending in the context of dental cost per person (DCPP). Seven associated factors analyzed were age, demographic, geographic, socioeconomic, regional wealth, the impact of the 8020-national campaign implementation (keep 20 teeth at age 80), and the effect of the home-visit dentistry for the elders. The average DCPP was high in older populations (75+) in all prefectures. The prefectures with the highest and lowest DCPP were significant compared to other states and retained their respective places in the cost hierarchy over the four years. The prefectures with more citizens participating in government assistance programs (GAP) had greater DCPPs. Dental costs were significantly related to geographic regions, age, per capita income, government assistance program prevalence, office complete denture frequency, and home visit care per patient. With a growing aging population, dental care costs will continue to increase, burdening its fiscal future. Associated factors identified should be considered to control the contentious increase of healthcare cost.

In this paper, we propose a new capacitor degradation evaluation method aimed at failure prediction and suitable for digitally controlled switching mode power supply (SMPS) for servers. Electrolytic capacitors have one of the highest component failure rates in SMPS; therefore, we attempt to detect an equivalent series resistance degradation of the electrolytic capacitor directly from the data fetched to a digital controller of the SMPS. With a SPICE simulation and a rapid control prototyping evaluation, we confirm the degradation can be detected by the data at a transient response under a normal operation without additional circuits. Even only 10% of a load step change, which commonly occurs in SMPS for servers, causes detectable transient response degradation.

The model-based development (MBD) technology is applied to design and implement a solar-to-hydrogen (STH) conversion system. Concentrator photovoltaic (CPV) modules, electrolyzers, and DC-DC converters are modeled precisely based on the actual component measured characteristics. To improve the system efficiency, a new control method is implemented on the precise simulation model. The control software is implemented using the auto-code generation technology for high reliability. The maximum power point tracking (MPPT) function and control method are confirmed by an experiment. The developed system achieves one-day STH efficiency of 18.78%, which is the highest efficiency to date for a sub-kilowatt-scale photovoltaic (PV) system under outdoor operation.

In this study, we developed a 1/8 brick size (58.4 mm × 22.9 mm × 13.0 mm) power-supply module converter, which is world smallest size for 450 W regulated isolation bus converter for high-performance telecommunication systems. We applied a model-based development process to obtain the high-power-density converter and designed the entire converter using the model. We built a three-level models of phase-shift full-bridge converter which are an analytical estimation model for basic architecture, a precise SPICE model for optimizing efficiency, and a control design model for stabilized operation. Our experimental results confirmed the design efficiency of the converter. In this report, we described the technologies that we used to achieve highly accurate estimations of efficiency.

The software-implemented online-degradation-detection method for digitally-controlled switching mode power supply (DC-SMPS) was studied. We found the voltage regulation degradation and the efficiency degradation are different output current dependence on applied duty. They are separately detectable by comparing the applied and the theoretical duty, which is calculated using micro-processing unit (MPU) fetched input/output IV data and pre-measured efficiency. This method is easily implementable as firmware and expected as a cost and space effective degradation detection/failure prediction method. In this paper, we describe the concept and verify it using MATLAB/Simulink simulation and RCP (Rapid Control Prototyping) evaluation.

In recent years, the scale of datacenter and its computing power has become larger and larger, however, the total consumed power of datacenter is not increased so much, on the contrary, slightly decreased. This is a frits of the continuous effort for the energy conservation in datacenter or ICT system. In this paper, resent trend of power Electronics in ICT systems are reported.

We propose a Hardware-in-the-Loop Simulation (HILS) system for the development of power supply control software. The HILS is software inspection technology for a micro controller for an embedded system such as an automotive system. The HILS emulates the control object in real time. The HILS is useful for software debugging and abnormal tests which have not destroyed the real control object. However, there are issues for conventional HILS systems. The control frequency is limited to under a few kilo Hertz (kHz). For the solution, we propose using a transfer function for real time simulation. The new system implements more than 100 kHz for a real time simulation. In this paper, the soft start, load step and abnormal test is experimentally confirmed.

Solar-to-hydrogen energy conversion is a promising technology because it enables high-capacity, long-term storage of solar energy. We propose a new highly efficient solar-to-hydrogen conversion system consisting of multiple converter-electrolyzer sets connected in parallel to a photovoltaic (PV) array. This system is flexible to apply to various PV configurations. One-day simulations based on measured PV and electrolyzer characteristics demonstrate very high maximum power point tracking (MPPT) efficiency (higher than 99.9%) and average power conversion efficiency (94.0%) on a clear sunny day. Annual energy production is expected to increase by 8.5%-point compared with a single converter system using one of the best commercial converter. The key elements of the high efficiency are the new system topology, a specially designed phase-shift full-bridge converter and a control method “P&O with converter scoring” algorithm.

We developed a high-current-density, point-of-load (POL) converter for high performance Field Programmable Gate Array (FPGA) used in telecommunications systems. We applied the model-based development (MBD) method to realize the high-current density converter. Model in the loop simulation (MILS) was applied for precise loss analysis of the converter. The rapid control prototyping process (RCP) was applied for the real circuit test. The development period was shortened to less than one third of that of conventional processes. To the best of our knowledge, this is the first practical example of MBD application for POL converter development. In this report, we explain how to apply the MBD method of a power supply design.

Among various converters, the LLC electric current resonant converter attracts attention because of high power density, low noise and high efficiency. However, this converter cannot apply the analysis of averaging method, and impossible to derivate the transfer function, so designing is difficult. In this study, we devised a method to derive a frequency response characteristic with a transfer function type using based on the way of thinking of averaging method, and succeeded expressing transfer function of the bode diagram which agreed with actual survey. Moreover, we derived poles from the transfer function, and showed the relation between the shape of the bode plots and poles.

In this paper, we report the low stability phenomenon of digitally controlled switching mode power supply (SMPS) caused by Equivalent Serial Resistance (ESR) degradation of electrolytic capacitor. The ESR of the output capacitor stack of SMPS is known as the dumping factor in a control loop that enhances SMPS stability. However, while studying electrolytic capacitor degradation in digitally controlled SMPS, we found the low stability phenomenon of SMPS with ESR degradation. Unlike an analog controlled SMPS, a time delay between an analog-digital (AD) sampling and a pulse width modulation (PWM) duty update creates ringing on a voltage waveform at the step load change response. The amplitude and frequency of this ringing becomes larger and higher with a higher ESR and is easily evaluated with a Micro-Processing Unit (MPU) used for digital control. We propose a new failure prediction method for a digitally controlled SMPS using this low stability phenomenon.

Identification of local strains is crucial because the local strains largely influence the ferroelectric property of BaTiO₃. The effects of local strains induced by external pressures on the Ti-L₂,₃ electron energy-loss near-edge structure (ELNES) of BaTiO₃ were theoretically investigated using first-principles multiplet calculations. We revealed that the effects appear in the position of the spectral threshold, namely the spectrum shifts to lower and higher energy sides by the tensile and compressive pressures, respectively. We concluded that conventional ELNES observations can identify only large strains induced by -10 GPa, and 0.1 eV energy resolution is required to identify ±2% of strains.

This paper presents a new cost effective method for a failure prediction of a digitally controlled Switching Mode Power Supply (SMPS). Electrolytic capacitor is known as one of the highest failure rate components in SMPS, so we tried to detect an Equivalent Series Resistance (ESR) degradation of the electrolytic capacitor directly from the data fetched to a digital controller of SMPS. With a SPICE simulation and a Rapid Control Prototyping (RCP) evaluation, we confirm the degradation can be detected by the data at a transient response under a normal operation. Even only 10 percent of a load step change, which commonly occurs in SMPS for servers, causes detectable transient response degradation.

Using an optimized system comprising concentrator photovoltaic (CPV) modules, electrolyzers, and DC/DC converters for dynamic control, we achieved a one-day solar-to-hydrogen (STH) efficiency of 18.78% — the highest value for a sub-kilowatt-scale photovoltaic (PV) system under outdoor operation. We clarified that incorporating high-efficiency CPV modules and DC/DC converters in PV-driven solar hydrogen production systems is essential for obtaining the highest STH efficiency. Furthermore, we noted that the overpotential of electrochemical (EC) cells is a bottleneck for the improvement in STH efficiency; therefore, future work should focus on reducing such an overpotential.

Artificial super-lattices of [(BaTiO3)/(SrTiO3)10]4 (BTO10/STO10) were fabricated on STO(001) substrate by the molecular beam epitaxy method (MBE), and the molecular layers of SrRuO3(SRO) was introduced into these superlattices as conductive layers. The superlattices introduced two conductive layers showed the enormous dielectric permittivity. On the other hand, the permittivity of the superlattice introduced one conductive layer was almost same as that of BTO10/STO10. In the case of introducing two conductive layers, the moving electrons between two layers induced the interfacial polarization. Especially, the superlattice with two SRO conductive layers, the distance between these layers in a superlattice is 18 molecular layers, showed the highest relaxation frequency 132 kHz and biggest capacitance.

In this paper, we report the first rapid control prototyping (RCP) system with a sub-nanosecond (ns) high-resolution Pulse Width Modulation (PWM) for server power supply circuits. Conventional RCP systems are designed mainly for engine and motor control. Based on the relevant response time and control accuracy requirements, their PWM update periods and resolutions are over 100 microseconds (µs) and 100 ns, respectively. The shortest update time reported thus far is 12.5 µs. However, for server power supply, the required PWM update period and resolution are less than 10 µs and sub-ns, respectively. Therefore, we developed a new interface board with high-speed and high-resolution PWM output, which is connected between an under-development power supply board and a commercially available RCP machine to increase the RCP system's speed and resolution. Moreover, we have developed new software that improves data transfer latency and maintains a constant PWM update period. The combination of the new interface board, high-performance RCP machine, and new software realizes the required short PWM update period and high-resolution PWM of 6.5 µs and 0.15 ns, respectively. This is the shortest PWM update period reported yet, and it is adequate for operating server power supply. We applied the new RCP system to a 500 W full bridge converter with 100 kHz feedback control. Frequency response and soft start functions are easily confirmed by the new RCP system.

We proposed a method for suppressing arc ignition in mechanical contact devices using a transient current switch and a capacitor. We applied the method to conventional reed switches. For the electric circuit analysis, we clarified the momentary voltage-current characteristics at breaking operation of reed switches by FEM analysis. We could also estimate the capacitance of the contact electrodes at the metal bridge rupture by FEM analysis, and would derive the non-arcing condition using SPICE simulation. The suitable capacitor value in the transient current circuit for arc ignition suppression would be depend on the load impedance, the power supply, the time depending contact resistance R(t)s, the contact capacitance, and the minimum arc voltage and current.

We proposed a new electric contact device that suppresses the arc phenomena. The functions of electric contacts are divided into energizing and switching for arc suppression. Switching contacts consist of multielectrodes and each electrode current is suppressed by the series resistance. For realization of multicontacting, cantilever beam array electrodes were formed on a silicon substrate using micro-electtomechanical systems (MEMS) technology. The finite element method was used to optimize the structure. The fabrication process of the cantilever was examined. Au-Au contact current of 0.97 A was broken without arc ignition.

An Au–Au contact gap was controlled by a LiNbO3 piezoelectric actuator. The control accuracy of the actuator was in the submicron range. Neither hysteresis nor creep was observed. Contact voltage, contact current, displacement of electrodes, and driving voltage of the actuator were continuously recorded for the opening contact. Measurement data for 1,500 contact operations (100 operations×15 steps of current value) were processed by a computer. Discharge and bridge phenomena were analyzed. For the electrical discharge phenomena, arc ignition probability, arc duration, and arc disappearance distance were derived. The length of the bridge and the bridge resistance were derived for the bridge phenomenon. In addition, the contact load was estimated from measurement data and numerical calculations. Our measurements show the possibility of data correlation among the factors affecting contact phenomena.

Optimal techniques for power supply with transient current circuit are introduced in this paper. The circuit reduces switching loss of buck converter's main switch effectively. However, in our previous researches, it could be operated with high efficiency only at heavy loading. The techniques to get rid of this disadvantage are proposed and the validity of it is verified through experiments.

The purpose of this study is to improve the efficiency of a boost-type power factor correction (PFC) circuit with a digital controller. One of the biggest losses in PFC circuits is the switching loss. Switching loss can be reduced by low boost ratio operation, but these results in a greater voltage drop at transient response. The voltage drop can be suppressed by using a high gain setting for the voltage control loop, but this lowers the power factor, which creates a harmonic distortion of the AC power line. To improve this trade-off, we developed a gain control method that adjusts the gain to high only at the moment of transient response. This method improves both the efficiency and the power factor of PFC circuits. We implemented the proposed method using a digital controller and demonstrated a power factor improvement of 0.08 points and an efficiency improvement of 0.4 points for a 2.5 kW PFC circuit.

Identification of local strains is crucial because the local strains largely influence the ferroelectric property of BaTiO₃. The effects of local strains induced by external pressures on the Ti-L₂,₃ electron energy-loss near-edge structure (ELNES) of BaTiO₃ were theoretically investigated using first-principles multiplet calculations. We revealed that the effects appear in the position of the spectral threshold, namely the spectrum shifts to lower and higher energy sides by the tensile and compressive pressures, respectively. We concluded that conventional ELNES observations can identify only large strains induced by -10 GPa, and 0.1 eV energy resolution is required to identify ±2% of strains.

Two phase double-ended forward converter is suitable for more than 2kW high efficiency power supply by the feature of low surge voltage. One issue of the converter is dead-time loss of synchronous rectifier FETs. In this paper, we propose a precise digital dead-time control method for a 2.5 kW (12 V / 208 A) output power supply. Proposed method is confirmed by experiment and theoretical analysis that the method reduces the 6 W loss at half load.

Wide-gap semiconductors such as SiC and GaN have seen widespread increase in interest as promising materials for use in next-generation power devices. In this paper, we present a 2.5-kW power supply unit (PSU) designed for ICT systems with engineering samples of Fujitsu Semiconductor Ltd. (FSL) 's GaN-HEMTs installed in the power factor collection (PFC) circuit. A new PFC circuit specially designed for GaN-HEMT is proposed: a semi-bridgeless design with a synchronous rectification return line. The bridgeless architecture is suitable for high-power and high-efficiency PSUs, and the synchronous rectification is designed to maximize the GaN-HEMT performance. As the GaN-HEMT does not have a body diode, the return current mainly flows through the return diodes in conventional semi-bridgeless PFCs. By applying synchronous rectifiers instead of return diodes, energy loss in the return line can be reduced to about 1/10. In our experiments, a maximum PSU efficiency of 94.3% was obtained with 230-V AC input and 12-V DC output.

The valences of manganese and vanadium oxides in multi-layer ceramic capacitors (MLCCs), sintered under a reducing atmosphere, were investigated using electron paramagnetic resonance; insulation resistance degradation was analyzed using impedance spectroscopy in highly accelerated lifetime tests to clarify the influences of manganese and vanadium on both the electrical properties and microstructure of MLCCs. The Mn(2+) was stable in the reducing-atmospheresintered MLCCs and formed a grain boundary. Vanadium mitigated insulation resistance degradation and increased the reliability of the MLCCs. Although V4+ was detected in MLCCs that had 0.20 mol% and 0.30 mol% of added vanadium, the electrical properties were dependent upon other ions, e.g., V(3+) or V(5+). All vanadium ions except for V(4+) decreased the insulation resistance of ceramic/electrode interface. This is because vanadium reduces electric field concentration at the ceramic/ electrode interface and delays the onset of oxygen vacancy migration in the early stages of a highly accelerated lifetime test.

Soft switching for power factor collection (PFC) of high-end server power supply unit (PSU) is studied. FET loss of PFC circuit is caused by Ron-related loss and switching loss. The switching loss consists of switching-speed-related part and output capacitance (Coss)-related part. The switching-speed related-part can be reduced by using a high-speed FET and high-power gate driver; however, Coss-related loss remains constant and makes efficiency worse especially in low-load region. We propose a new soft switching PFC circuit designed for Coss-related loss reduction and demonstrated that the PFC loss was reduced by half at 20% load with both SPICE simulation and prototype circuit. In the data server case, the average load of the PSU is usually less than 30% [1] when redundant PSU is used, so this circuit is very effective for energy saving of data center. (4 pages)

In this paper, a transient current circuit is introduced. The circuit evidently reduces switching loss of buck converter main switch dramatically. This topology enables to operate high-frequency. The validity of the transient current circuit is verified through simulations and experiments.

The valence of vanadium was measured by electron paramagnetic resonance in order to explain the decrease in insulation resistance (IR) and the improvement in highly accelerated lifetime that resulted from the addition of vanadium. V4+ was detected in specimens with vanadium contents of 0.20 and 0.30 mol %, while no V4+ was detected in a specimen with a vanadium content of 0.06 mol %. It was also revealed that the content of the vanadium except for V4+ are the main factor responsible for the decrease in IR and the improvement in lifetime. The impedance of BaTiO3-based materials in multilayer ceramic capacitors with various vanadium contents was investigated in order to determine the mechanism of improving the highly accelerated lifetime using a four resistance and capacitor section electrical equivalent circuit. All four resistance components (R components) decreased with an increase in vanadium content. During the lifetime test, all four R components were degraded. In particular, the R component corresponding to the ceramic/internal electrode interface regions was more strongly degraded than the other three R components, and it was found that this component was the main factor responsible for the degradation of IR during the test. The resistance degradation of this component tended to occur slowly when the vanadium content increased, which resulted in the improvement in lifetime. The primary part of this degradation was implied to be controlled by diffusion.