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The JT-60SA central solenoid (CS), which consists of four stacked modules, is cooled to an operating temperature of 4.5 K by supercritical helium (SHe). During cool-down from room temperature to 4.5 K, in order to avoid a damage on the coil, it is required to reduce thermal stress due to temperature difference in the coil. In the cool-down operation, the CS needs to control the maximum temperature difference in the longitudinal direction of the cable-in-conduit (CIC) conductor below 40 K. However, since that could damage the coil, correctly estimating the temperature distribution in the conductor is important for ensuring the cool-down operation is performed safely. In the present study, the JT-60SA CS module was prepared and the inlet and outlet temperatures, as well as the SHe mass flow rate, were measured until the CS module was cooled to operating temperature, after which a CS module simulation was performed in order to determine the effect of the inlet temperature on the cool-down speed. From the simulation results, it was concluded that the average cool-down speed was 0.73 K/h and the CS module reached 80 K in approximately 8.3 days while maintaining the maximum temperature difference within 40 K. Furthermore, the temperature difference between the inlet and outlet was kept within 25 K in order to limit the thermal stress. Taken together, the results of our analyses provide fundamental data that can be used to evaluate the safe cool-down operation of the coil and thus protect the coil systems.

In recent years, examples of adopting passive controlled building are increasing. In particular, when long-period seismic ground motion is applied to passive controlled building having a hysteresis damper, in addition to the maximum response value, evaluation by cumulative value is also required. As a very effective method for evaluating the cumulative value, there is a energy based method which evaluates with the total amount of energy input by seismic motion. However, when this method is applied to the passive controlled building, only studies taking into consideration the plasticization of the main frame are performed only in the first layer. In this paper, focusing on the maximum deformation, we propose a prediction method of the maximum deformation in all layers considering plasticization of the main frame.

In recent years, there has been an increase in the adoption of passive-controlled buildings. Specifically, evaluation by cumulative value is also required in addition to the maximum response value when long-period seismic ground motion is applied to passive-controlled buildings with hysteresis damper. An energy-based method that evaluates the total amount of energy input by seismic motion is an extremely effective method to evaluate the cumulative value. However, when the method is applied to a passive-controlled building, studies that consider the plasticization of the main frame are performed only in the first story. In this study, we focused on maximum deformation, and we propose a prediction method for maximum deformation in all stories by considering plasticization of the main frame.

The JT-60SA central solenoid (CS), which consists of four stacked modules, is cooled to an operating temperature of 4.5 K by supercritical helium (SHe). During cool-down from room temperature to 4.5 K, in order to avoid a damage on the coil, it is required to reduce thermal stress due to temperature difference in the coil. In the cool-down operation, the CS needs to control the maximum temperature difference in the longitudinal direction of the cable-in-conduit (CIC) conductor below 40 K. However, since that could damage the coil, correctly estimating the temperature distribution in the conductor is important for ensuring the cooldown operation is performed safely. In the present study, the JT- 60SA CS module was prepared and the inlet and outlet temperatures, as well as the SHe mass flow rate, were measured until the CS module was cooled to operating temperature, after which a CS module simulation was performed in order to determine the effect of the inlet temperature on the cool-down speed. From the simulation results, it was concluded that the average cool-down speed was 0.73 K/h and the CS module reached 80 K in approximately 8.3 days while maintaining the maximum temperature difference within 40 K. Furthermore, the temperature difference between the inlet and outlet was kept within 25 K in order to limit the thermal stress. Taken together, the results of our analyses provide fundamental data that can be used to evaluate the safe cool-down operation of the coil and thus protect the coil systems., Applied Superconductivity Conference 2020 (ASC2020)

In recent years, demand for large logistics facilities is rising under the influence of expansion of retail chain development and online market. Most of these facilities are low- and middle-rise steel structures, and it is vital that these structures are earthquake resistant. An energy-based method for earthquake-induced response of a building is very useful for the evaluation of the cumulative damage of structures. However, this method is not applied to structures with uneven stiffness distribution in the height direction like large logistics facilities. In this paper, we analyze whether this method can be expanded to such structures by comparing cumulative damage distribution predicted using this method and calculated by time-history analysis. Moreover, the effect of difference in strength calculation on cumulative damage distribution prediction is examined.