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As technology has improved in recent years, it has become possible to create new valuable functions by combining various devices and sensors in a network. This concept is referred to as the Internet of Things (IoT), and predictive maintenance is a new valuable function associated with the IoT. In large-scale experimental facilities with many researchers, it is not desirable that experiments cannot be performed due to sudden failure of equipment. For this reason, it is important to predict the failure in advance based on the measurement results of sensors and to perform repairs in a planned manner. On the Q-shu University experiment with steady-state spherical tokamak (QUEST) large experimental device, it is necessary to drive a large current of 50 kA, and the diagnosis of its power line deterioration is well performed as predictive maintenance through the evaluation of its contact resistances of several micro ohms order on the network. In addition, as an example of the IoT, mechanisms to assist safe operation, such as a sound alarm system and an entrance management system, are built by sharing experimental information between devices via the network., Computer Science; Electrical Engineering; Safety engineering; Internet of Things; System Diagnostics; Electric Power Transmission; System Fault Detection; Computer-Aided Engineering; Predictive maintenance; IoT; safety operation; FPGA; QUEST

In this paper, the authors propose a method of improvement of power quality by static synchronous compensators (STATCOMs) for low voltage system (single-phase STATCOMs) added the function of harmonic suppression. In the proposal method, the STATCOMs control the voltage of the distribution system within the proper range by compensating the reactive power. Additionally, they are operated as the filtering function and suppress harmonics of the voltage of the distribution system. The filtering gain is determined by PI controlling the error between the voltage total harmonic distortion of the point voltage at the installation of STATCOMs and the target value. In order to verify the validity of the proposal method, the numerical calculations are carried out by using an analytical model of distribution system which interconnected photovoltaic generation systems. Simulation results show the effect of improvement of power quality on both sides of voltage deviation and harmonics.

In tokamaks, the temperature of the plasma-facing wall is an important parameter for achieving particle balance and therefore steady-state operation. QUEST, which is a middle-sized spherical tokamak, has hot walls that act as plasma-facing walls. They can be actively heated with sheath heaters and actively cooled with water. To control the wall temperature, heating and cooling systems have been developed. These systems adjust the power of the sheath heaters and the motor valves of the cooling system, respectively. The two systems communicate via Ethernet through UDP and control the hot-wall temperature cooperatively. The plasma control system (PCS) in QUEST has also been modified, especially with respect to gas fueling, in order to enable long-duration plasma sustainment. A feedback controller has been installed in the PCS, together with a mass flow controller, allowing Hα emission from the plasma which is used as a reference signal, to be well controlled. Plasma density calculations using a field-programmable gate array are proposed for the feedback control system.

Recently, non-linear loads have diversified and increased. It results in deterioration of power quality on a distribution system, since the equipment, which includes the non-linear loads, generates harmonics. The harmonics cause not only deterioration of power quality but also further various problems. Nowadays, the state of harmonics is becoming evident by the recent researches. However, since the harmonic analysis by using a detailed model of distribution system is too difficult, the analysis is carried out by a simplified model. In this paper, the authors construct an analytical distribution system model in consideration of the non-linear loads with the harmonic sources based on the practical data. Moreover, the influence analyses of harmonics are carried out by using this model. In addition, the authors estimate the harmonic sources in the simplified distribution system.

The plasma control system (PCS) of QUEST is developed according to the progress of QUEST project. Since one of the critical goals of the project is to achieve the steady-state operation with high temperature vacuum vessel wall, the PCS is also required to have the capability to control the plasma for a long period. For the increase of the loads to processing power of the PCS, the PCS is decentralized with the use of reflective memories (RFMs). The PCS controls the plasma edge position with the real-time identification of plasma current and its position. This identification is done with not only flux loops but also hall sensors. The gas fueling method by piezo valve with monitoring the Hα signal filtered by a digital low-pass filter are proposed and suitable for the steady-state operation on QUEST. The present status and prospect of the PCS are presented with recent topics.

In the present RF-driven divertor plasma of QUEST, it has been observed that orbit-driven current flows in the open magnetic surfaces outside of the closed magnetic surfaces. To observe this phenomenon and the characteristics of the orbit-driven current, current density profiles have been calculated on two different equilibrium conditions. We calculated current density profiles from particle guiding center orbits both for the fundamental and the second harmonic resonances for the 8.2 GHz electron cyclotron current drive. From this calculation, hollow current density profiles have been obtained with significant characteristics on both conditions. Only positive current distribution has been observed in the open magnetic surfaces outside of the closed magnetic surfaces.

In order to evaluate the magnetic surface current density distributions, the electron guiding center orbits were calculated with the equilibrium fitting plasma equilibrium analysis. The current density distributions in electron cyclotron-heated plasma were estimated from the orbit analyses in the equilibrium plasma shaping for the fundamental and the second-harmonic resonant electrons separately. The current density distribution profiles on the equatorial plane were obtained for the electrons with initially positive and negative velocities parallel to the magnetic field direction as well as the trapped electrons. The surface averaged current density profiles of the closed flux surfaces were also evaluated. A significant amount of the positive current density distributions appeared outside the last closed flux surface (LCFS), while all the negative current density distributions were evaluated inside the LCFS. The trapped electrons being the second-harmonic electron cyclotron resonant contributed the negative current inside the LCFS. The positive current density distributions outside the LCFS were significant for the driven current density for both the fundamental and second-harmonic resonances.

In recent years, the debasement of power quality of a distribution system such as the increase of power system harmonics has been apprehended. It is thought to be causally related to the diversification of loads by progress of power electronics technology and the increase of the number of interconnection of distributed generators for home use with the reduction of the effect on the environment. The harmonics cause not only deterioration of power quality but also further various problems. In this paper, the authors propose an estimation method of harmonic sources by separating the harmonic current flowing through the distribution lines. In addition, the authors carry out the numerical calculation and experiment in order to verify the validity of the proposed method.

A drift error correction technique with machine vision and a real-time equilibrium calculation code have been developed on the QUEST (Q-shu university experiment with the steady-state spherical tokamak) for steady-state operation. The drift error caused by the long time-integration of magnetic raw signals has to be removed. With a captured image of the plasma’s cross section, the plasma’s position is identified by use of image filters. The measured magnetic flux values are corrected to the calculated flux values estimated by using this plasma position. The correction with the captured image work as expected in the preliminary result using a flashlight instead of a plasma.

A 28~GHz system with a high-power gyrotron tube has been used for the QUEST spherical tokamak to form an over-dense plasma for electron Bernstein wave heating (EBWH) and current drive with an 8.2~GHz-wave. Non-inductive high-density plasma ramp-up experiments with dual-frequency (dual$-f$) electron cyclotron (EC) [ 8.2~GHz and 28~GHz ] waves were conducted. A spontaneous density jump (SDJ) to an over-dense state was observed as a bifurcation phenomenon in the dual$-f$ wave experiment. The over-dense plasma on the 8.2~GHz-wave was non-inductively ramped up to 25~kA, and was maintained for 0.4~s under stable plasma equilibrium after two such jumps in one shot. Heating to mildly energetic electrons and bulk electrons was observed even in the over-dense region. The electrostatic EBWH effect on the mildly energetic electrons in the over-dense region is assessed following a dispersion analysis of the 8.2 GHz-wave. The bulk electron heating effect observed is explained as heat exchange from mildly energetic electrons heated by the electrostatic EBWH wave. Remarkably, a high hard-X-ray-radiation temperature ~ 500~keV was also observed in tangential viewing for current-carrying electrons in the over-dense core region. Synergetic heating from the overlap of different 28~GHz EC harmonic resonances as well as higher harmonic heating is discussed for maintaining the highly energetic electrons in the over-dense core region. In addition, the SDJ process and mechanism are considered based on the discussion of the electron heating effects with the 8.2 GHz-wave.

A plasma control system to sustain divertor configurations is developed on QUEST (Q-shu university experiment with steady-state spherical tokamak). Magnetic fluxes are numerically integrated at 100 kHz using FPGA (Field-Programmable Gate Array) modules and transferred to a main calculation loop at 4 kHz. With these signals, plasma shapes are identified in real time at 2 kHz under the assumption that the plasma current can be represented as one filament current. This calculation is done in another calculation loop in parallel by taking advantage of a multi-core processor of the plasma control system. The inside and outside plasma edge positions are controlled to their target positions using PID (proportional-integral-derivative) control loops. Whereas the outside edge position can not be controlled by the outer PF coil current, the inside edge position can be controlled by the inner PF coil current.

In this study, we made experiments by the simulated PV system for understanding the cause of disconnection when instantaneous voltage sag occurs. Moreover, it is understood that the PCS with the voltage phase jump detection method which is one of the main causes of the disconnection. We modeled it in the simulation. When fault occurs, even though the residual voltage is more than 20 % and the voltage sag time is within 1.0 sec, the PCS disconnected by the voltage phase jump detection was confirmed in the simulation results. If a large number of PV systems are interconnected in the power system, we verified through the simulation that the interaction caused by the disconnection which generated by the voltage phase jump detection. We proposed threshold limit value of islanding detection. The validity of proposed method was verified through the simulation in this study.

A CW phased-array antenna system for electron cyclotron/Bernstein wave heating and current drive (ECWH/CD, EBWH/CD) experiments was developed in the QUEST. The antenna was designed to excite an elliptically polarized pure O-mode wave in oblique injection for the O-X-B mode conversion scenario, and its good performance was confirmed at a high power level. Long pulse discharges with a plasma current of 10 kA and 15 kA were non-inductively attained for 37 s and 20 s, respectively, with only radio frequency (RF) power. Divertor configurationswere also obtained in the RF-sustained plasmas. A new operational window for sustained plasma current was observed in the high-density plasma with a higher RF incident power. Two new heating and current drive systems with an 8.56GHz klystron and a 28GHz gyrotron are being prepared to conduct CW EBWH/CD experiments in the high-density plasma. © 2012 The Japan Society of Plasma Science and Nuclear Fusion Research.

In this paper, we proposed the mathematical model of campus by measurement data and theoretical approach. We measure dynamic characteristic and static characteristic of load in a system. Power capacitors in the university are assumed to be electric power customer's load. The load model is presumed by combining them and the linear model calculated theoretically. The line voltage and the line current are measured, and we calculate the line load capacity in distribution system of campus. The load fluctuation of distribution system during a day is observed. The load will be modelized by evaluating a lot of data. We can forecast the demand of electric power by few information that is the load model and the measurement data of receiving end.

In recent years, the debasement of the power quality of a distribution system such as deterioration of voltage imbalance and current imbalance or the increase of harmonics has been apprehended with diversification of the load by progress of power electronics technology and with increase of the amount of connection of a distributed generators for home use with the reduction of the effect on the environment. In this paper, the authors propose the restraint method of harmonics and improvement of voltage imbalance in distribution system utilizing the power conditioner systems of photovoltaic systems and verify the validity of the proposal method by the numerical calculation using an analytical model of distribution system.

Particle retention and recycling in plasma fusion devices are generally associated with the diffusion of atomic hydrogen into the materials. The resulted permeation of atomic hydrogen is known as plasma driven permeation (PDP). This permeation may also be significant, even in the walls, which are not directly exposed to the plasma. Under similar conditions, the permeation flux (Γperm) of hydrogen through a 30 μm thick Ni membrane heated at 412–575 K has been measured in the spherical tokamak QUEST. Γperm is being measured during the scans of different operating parameters like RF power (PRF), chamber pressure (Pchamber), discharge widths (τdis) and vertical magnetic field (BZ). Simultaneously edge plasma density and spectral intensities of atomic (Balmer) lines and molecular (Fulcher) bands have been compared with the permeation measurements. A linear relationship has been established between the time integrated Γperm i.e. permeation fluence (Qperm) and the time integrated Hα intensity i.e. Hα fluence (Qα). Qperm also shows a strong relationship with the edge plasma density and various spectral fluences. The obtained results are discussed for exploring the applicability of the permeation probes in measuring the atomic flux near the first walls.

In this paper, we propose an experimental multiobjective evaluation method based on the use of distribution network equipment to evaluate distribution network configuration candidates with distributed generators (DGs), such as photovoltaic generation systems and wind power generation systems, by hourly changing states of sectionalizing switches satisfying constraints of voltage and line current limit. In the proposed experimental multiobjective evaluation method, the optimal network configuration is determined by using multiobjective evaluation based on total distribution loss rate, maximum voltage total harmonic distortion, and maximum voltage imbalance rate in order to reduce distribution loss and to keep power quality. The proposed method is applied to radial and loop distribution network configurations by using an experiment of scaled-down three-phase distribution network with 1 bank distribution transformer, 5 distribution lines, 5 sectionalizing switches, 12 single-phase loads, and 5 DGs. © 2008 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

In TRIAM-1M, plasma discharge can be sustained for over five hours [H. Zushi, et al., Steady-state tokamak operation, ITB transition and sustainment and ECCD experiments in TRIAM-1M, Nucl. Fusion 45 (2005) S142–S156]. In order to avoid sitting in front of one console for the purpose of monitoring the plasma discharge, it is recommended that the experimental information be accessible from any location at any time. In addition, simple services to access experimental information are required in order to promote the participation of multiple researchers in the TRIAM-1M experiment. Thus, A WEB-based integrated data processing system that provides management for experiment planning, an experimental log, numerical data, and plasma supervision has been installed in the TRIAM-1M. These services are composed primarily of an Apache WEB server, a Tomcat JSP/Servlet container, and a MySQL relational database. This system is constructed using the object-oriented Java language, which is easy to maintain and develop because of the intrinsic characteristics of the Java language. When participating in experiments, researchers are required only to prepare a WEB browser on any platform and are no longer required to memorize complex operations because all services are provided with a uniform user interface through a WEB browser. Furthermore, with the integration of these services, the required information and numerical data can be provided promptly by tracing HTML links that are created dynamically by server applications.

On CPD [1] (Compact PWI experimental Device) experiment, information of electronic logbook and sequence status are distributed by Web services to prepare future experimental environment such as steady state operation and remote participation. Hence, all the researchers can acquire information with a Web browser installed on a personal computer if they are connected to the Internet. However, to carry a notebook computer all the time is a burden to researchers. Furthermore, the researchers may not be always connected to the Internet. Mobile phones are superior in portability compared to notebook computers, and are easy to connect with Internet through the wireless network of the telecom carriers. Moreover, since recent mobile phones have full browsing function, their affinities to the Web services are becoming high. On this account, Web services for mobile phones are developed to access experimental information. For sequence monitoring, a mobile application MIDlet that utilizes special functions of mobile phone such as sound and vibration is also developed to draw attentions of researchers to sequence status.

A discharge longer than 5 h was successfully achieved on TRIAM-1M by fully non-inductive lower hybrid current drive (LHCD). The heat load distribution into the plasma facing components (PFCs) during the 5 h discharge was investigated using calorimetric measurements, which estimated that the injected radio frequency (RF) power coincided with the total heat load amount to the PFCs. The power balance, including the portion of direct loss power of the fast electrons and the heat flux due to the charge exchange (CX) process, was also investigated.

Purpose: Methylation of H3 at lysine 4 (H3 Lys4) may be correlated with active gene trascription, whereas methylation of H3 at lysine 9 (H3 Lys9) may be linked to gene repression in murine cells and Schizosaccharomyces pombe.Methods: Using Western blot analysis, heat-induced changes were studied in two human oral cancer cell lines, HSC4 (thermoresistant cells) and KB (thermosensitive cells). Histone H3 changes were studied; in particular for H3-Lys4 and H3-Lys9 methylation combined with KNK437.Results: Heating of HSC4 cells at 45°C for 20 min and KB cells for 3 min gradually increased H3-Lys4 and H3-Lys9 methylation. Treatment of both cells with 100 µM KNK437 before or after heat-treatment inhibited methylation of H3-Lys4, while methylation of H3 Lys9 remained unaffected. Use of KNK437 either before or after heat treatment inhibited the expression of HSP70.Conclusions: The findings suggest that heat-induced methylation of histone H3 may be correlated with the induction of HSPs by heating.

Single exposure of cells to hyperthermic treatment, makes them thermotolerant to subsequent heat treatment. Tumor cells that express normal or elevated levels of HSPs show thermotolerence. KNK437, a chemically synthesized benzylidene lactam compound, has been specifically found to inhibit the synthesis of heat shock proteins and thus leading to significant reduction in the thermotolerance of cells. However, mechanisms by which KNK437 inhibits thermotolerence are still not clearly understood. In this study an attempt has been made to elucidate the mechanisms of inhibition of HSPs by KNK437 in 2 cell lines of human oral squamous cell carcinma with varying sensitivities (HSC4 ; heat-resistant and KB ; heat-sensitive) with an aim to identify which of the HSPs are targeted by KNK437. Single administration of 100μM KNK437-treatment always resulted in a higher than 85% cell survival compared to the untreated groups, indicating the KNK437 had a minimum cytotoxic effect in both cell lines. Combination of hyperthermia with KNK437 after heat shock, specifically inhibited the induction of HSPs, where the expression of HSP27, HSP40, HSP70 and HSP90 reduced in a time dependent manner. Interestingly, the hyperthermic treatment combined with KNK437 produced supra-reductive effect on the expression of HSP27 and HSP90 in HSC4, HSP27, HSP40 and HSP90 in KB cells, when compared to heat treatment alone. Our results indicate that inhibition of HSPs by KNK437 plays an important role in inhibiting the thermotolerence of the cells and may be a valuable to improve the efficacy of oral cancer during hyperthermic therapy.

An electron cyclotron heating (ECH) system has been installed on the TRIAM-1M tokamak, which produces a 170 GHz microwave up to 260 kW at the window of the gyrotron for 5 sec. After the Matching Optical Unit (MOU) converts the microwave to a Gaussian beam, a microwave power of 200 kW is transmitted by a corrugated waveguide of 63.5 mm in diameter. Tests confirmed these specifications, and the fundamental ordinary electron cyclotron (EC) wave of 170 GHz up to 120 kW was injected into the vacuum vessel of the TRIAM-1M in order to ionize neutral hydrogen gas to make source plasma, which is expected to reduce flux consumption in the case of current start-up by means of Ohmic heating (OH) coils. Though the breakdown does not occur at the input RF power, PRF = 40 kW with the neutral gas pressure, p = 1.3×10−3Pa, high-density plasma (more than 0.7×1019m−3) is produced at PRF = 100 kW. In the range of PRF = 40−100 kW, the electron density is proportional to PRF.

A new tissue-equivalent MRI phantom based on carrageenan gel was developed. Carrageenan gel is an ideal solidifying agent for making large, strong phantoms in a wide variety of shapes. GdCl(3) was added as a T(1) modifier and agarose as a T(2) modifier. The relaxation times of a very large number of samples were estimated using 1.5-T clinical MRI equipment. The developed phantom was found to have a T(1) value of 202-1904 ms and a T(2) value of 38-423 ms when the GdCl(3) concentration was varied from 0-140 mumol/kg and the agarose concentration was varied from 0-1.6% in a carrageenan concentration that was fixed at 3%. The range of measured relaxation times covered those of all types of human tissue. Empirical formulas linking the relaxation time with the concentration of the modifier were established to enable the accurate and easy calculation of the modifier concentration needed to achieve the required relaxation times. This enables the creation of a phantom having an arbitrary combination of T(1) and T(2) values and which is capable of retaining its shape.

Sensorless sensing experiments of the plasma horizontal position have been carried out in the superconducting tokamak HT-7. The horizontal position is calculated from the vertical field coil current and voltage in two ways. The calculations are made focusing on the low frequency component and the ripple frequency component of the power supply. In the latter case, there is no drift problem and the error is lower than 2% of the plasma minor radius.

The operation of tokamak devices is based on the principle of the transformer, so it has been considered that pulse operation of such devices is inevitable. But the superconducting high-field tokamak TRIAM-1M has been demonstrated continuous operation for last 15 years and succeeded in sustaining 3 hours of constant operation in 2001. Fusion reactors of the future will use the center solenoid (CS) coil only in the ramp-up phase of the plasma current. If the coil is removed from the tokamak device, the device can be simplified and its cost will be decreased. In TRIAM-1M experiments, a perfect CS-free ramp-up was demonstrated and succeeded in sustaining the plasma current longer than 30 s. In this paper, the operation scenario, especially plasma position control, and the results of the analysis of plasma control are described.

The study of wall recycling of long duration discharge has been carried out using 2.45 GHz and 8.2 GHz lower hybrid current drive in the superconducting tokamak TRIAM-1M. The recycling coefficient increases with two time constants. One is 1˜3 s and the other is ˜30 s. These two time constants are common to low (˜2 × 1018 m-3) and high (˜1 × 1019 m-3) density discharges. In the ultra-long discharge, the wall repeats a process of being saturated and refreshed. One possible candidate of the mechanism of wall refreshment is co-deposition of in vessel element (i.e. Molybdenum). In the high density discharge, the wall becomes saturated and the discharge is terminated due to the density increase. The achievable discharge duration becomes shorter as the plasma density is higher.

Radioactive iodine isotopes are necessary to be handled carefully, because they scatter easily. As air concentration limits of the radioisotopes are very low levels, we should prepare the measurement technique using a large-volume aspirator and largescale equipments for environment measurement in radiation controlled areas. In the present study, we designed and manufactured a simple set of holder and charcoal filter connected to a foot pump, and we examined the validity of the system. The collecting efficiency of airborne iodine-125 by this system was 0.379±0.107. However, in the case that 10 L air were filtered by this system and counted for 10 min by a NaI (Tl) well-type scintillation counter, it was shown that iodine-125 at air concentration limit could be measured.

On startup of a brushless DC servomotor, it is necessary to detect of its magnetic pole position, to generate the torque effectively. Numerous brushless DC servomotors provide a high angle resolution encoder for the speed control and position control. It can use as a magnetic pole position detection, too. There are the absolute encoder and the incremental encoder. If a brushless DC servomotor provides an absolute encoder, the motor can startup, because it is necessary to detect of its absolute position for the magnetic pole position detection. However, it is not used except uses of demands for high accuracy because the encoder is expensive. The incremental encoder in general use cannot detect the magnetic pole position when the motor starts, and so it demands an exclusive magnetic pole position sensor till a standard signal output of the encoder.This paper describes a method of the magnetic pole position detection of a brushless DC servomotor with an incremental encoder only use the encoder without an exclusive magnetic pole position sensor. The feature of this method is that can detect the magnetic pole position with very little revolutions in a matter of minutes during the motor starts.

In the future, the power quality will decrease by the introduction of a lot of renewable energy sources. The topic of this research is a new method of operation of PCS (power conditioning systems) in the future distribution system. The purpose of this research is development of PCS with a function of improvement of the distribution system. Therefore, the authors propose a method of the power quality improvement of the distribution system by PCS. In addition, the authors construct the control logic to use in PCS. The control logic suggests adding harmonic restraint function to conventional control. These were verified by simulation and an experiment. As the results, we confirmed that basic operation of PCS being carried out, harmonics were restrained, and power quality had improved.

The characteristic development of thermotolerance was examined in tsAF8 cells, which were temperature sensitive cell line derived from BHK21. tsAF8 cells lose RNA polymerase II activity and arrest in the G1 phase of the cell cycle at the nonpermissive temperature of 39.5-40.6 degrees C. tsAF8 cells were pre-heated at 45 degrees C for 20 min, incubated at 34 or 39.7 degrees C for different durations, and then heated again at 45 degrees C for 30 min. The cells were trypsinized immediately after the second heating to evaluate cell survival. As a result, thermotolerance was developed rapidly in the cells incubated at 34 degrees C. However, the survival rate of the cells incubated at 39.7 degrees C was almost constant. Thermotolerance of BHK21 cells, which were wild-type cells of tsAF8 cells, developed at 39.7 degrees C. These results suggest that thermotolerance may be inhibited in tsAF8 cells incubated at 39.7 degrees C, and that some metabolism which is inhibited in tsAF8 cells at 39.7 degrees C may be related to thermotolerance development.