Solar cells generate electricity by obtaining energy from sunlight, but their heat generation characteristics with respect to the load have not been analyzed. There are also PVT(Photovoltaic and Thermal) systems that also use solar heat to improve overall efficiency. In this system, the solar cells are cooled, which improves their electrical characteristics. To achieve more precise control of this system, it is important to estimate the heat generated by the solar cells themselves. Therefore, this paper analyzes the heating power inside the solar cell for the temperature changes by operating point of the solar cell. This simulation and experimentation enabled us to predict the internal heating of the solar cells. By utilizing these characteristics, we can aim to increase the efficiency of solar cells and the overall efficiency of PVT systems.

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Heat transport properties of amorphous Si, SiGe and Ge thin films were investigated by comparing measured and theoretical thermal conductivities. The thermal conductivity was measured by the 3ω method. The theoretical thermal conductivity was calculated using the minimum heat transfer model based on the Einstein model, which is close to the heat transport in amorphous materials. The theoretical thermal conductivity was determined from the minimum heat transfer model with the phonon group velocity measured from the Young's modulus using the nanoindentation. The measured thermal conductivities of three types of the thin films approximately corresponds to those of theoretical thermal conductivities because they obtained amorphous structures. However, the measured and theoretical thermal conductivities of the three thin films followed the order of Si > Ge> SiGe and Si > SiGe > Ge, respectively. This difference occurred because the measured thermal conductivities included the effect of the interaction of different types of atoms, while the theoretical values did not account for this effect.

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Nano-carbon was formed by in-liquid plasma method from ethanol and 2-propanol as a support material of platinum catalyst for fuel cell. The higher formation speed of nano-carbon was observed by using 2-propanol. The platinum catalyst particles were formed on the nano-carbon surface by the in-liquid plasma method. Formed platinum catalyst was applied to fuel cell. The fuel cell was characterized.

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It is important to ensure the stable operation of PV systems with their increasingly widespread use.For the complex sampling process of most PV fault diagnosis systems, this paper proposes an intelligent detection method of PV cell faults based on the I-V characteristic trend, which takes only the I-V characteristic trend of PV cell as a training sample to achieve high accuracy diagnosis of the three states of normal operation, hot-spot faults and abnormal aging. BP (back propagation) neural network algorithm is used as the training algorithm, and the experimental results show that the average accuracy of the BP neural network with the I-V trend as the training object is 99.3%, which achieves high accuracy fault diagnosis.

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This study improves the thermoelectric performance of single-walled carbon nanotube (SWCNT) films with different concentrations of SWCNT dispersions with an anionic surfactant. The SWCNT dispersions were prepared by adding SWCNT powders and sodium dodecylbenzene sulfonate (SDBS) as the anionic surfactant in deionized water, followed by ultrasonic dispersion using a homogenizer. The dispersion concentration, which is defined as the weight ratio of SWCNTs and SDBS to deionized water, was varied from 0.1 to 0.3 wt%. The freestanding SWCNT films (Buckypaper) were prepared by vacuum filtration. In-plane thermoelectric properties, including the Seebeck coefficient, electrical conductivity, and power factor, of the SWCNT films were measured at approximately 300 K. As a result, all thermoelectric properties showed the highest values at a concentration of 0.2 wt%. These results indicate that the dispersion condition is a key factor in improving thermoelectric performance, and the findings in this study are useful for the improvement of various functional materials using dispersion processes.

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In recent years, most heat exchangers are manufactured by brazing of aluminum alloys. In this process, aluminum alloys easily oxidize and have a strong oxide film, which reduces brazing-ability. Therefore, flux must be used to remove the oxide film and to prevent oxidation. However, flux can contaminate the working environment, and its residue can cause metal corrosion. Hence, there is a need for aluminum brazing without using flux. Recently, there have been reports of flux-free brazing methods based on the thermal expansion of the base metal due to rapid heating and the breakdown of the oxide film caused by the reaction of magnesium in the aluminum alloy. The term "flux-free" here means without using flux at all. In this study, brazing was performed using A6061 as the base metal and A4045 foil as the brazing filler metal in an infrared imaging furnace under an argon gas atmosphere. The brazing temperatures were set at 575°C, 580°C, 585°C, and 590°C, and the holding time was 3 minutes. The results of microstructural observation and EPMA analysis revealed significant impact of brazing temperature on the results. Voids were found at the interface, which could be related to gap setting at the brazing position.

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FP-613 is a powder brazing filler metal with excellent corrosion resistance. There is a market need for a foil type brazing filler metal with a composition equivalent to FP-613. To form a foil, boron must be added. Boron can create a chromium deficient layer and deteriorated corrosion resistance. We investigated the corrosion resistance of test pieces brazed using a foil brazing filler metal containing boron. Even when 0.5mass%B was added to the foil type brazing filler metal having the composition of FP-613, the corrosion resistance was not affected. Therefore, it was found that a foil brazing filler metal with the composition of FP-613 containing 0.5mass%B could be used. This allows us to supply brazing filler metal with good corrosion resistance in a new form.

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The polymer electrolyte fuel cell (PEFC) was characterized by the impedance measurement method. It is revealed the fuel cell has two inner resistances such as serial resistance (RS) and parallel resistance (RP). The parallel resistance is related to catalytic reaction resistance. The measured value of parallel resistance was depended on the applied DC current. In this paper, the proper measurement condition for the parallel resistance is discussed.

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YBa₂Cu₃O_7-ẟ (YBCO) round wires with high critical current density (J_c) were developed by the Powder—in—Tube method and melt—growth process. For the sheath material of the wire, silver was selected since it doesn’t react with YBCO, it is not oxidized at high temperatures in the air, and it is permeable to oxygen. Since BaCu₂O₂ has a melting point of 880°C, which is lower than silver, BaCu₂O₂ and Y₂BaCuO₅ were prepared as raw materials. The YBCO round wire was developed by melt-growth process in oxygen pressure control condition. After the heat-treatment, large YBCO grains were observed. The critical current density of the wire reached 46 kA⁄cm² at 4.2 K in self-field and 33 kA⁄cm² in 14 T. Unfortunately, since current sharing through the silver occurred during the measurements, the exact Ic should be evaluated.

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In this study, a thermoelectric converter (TEG) was fabricated using a SWCNT/mesh membrane in which a mesh (polyphenylene sulfide: PPS) was coated with SWCNTs. Previously, only SWCNT/mesh membranes with p-type thermoelectric properties could be fabricated, but this time we will fabricate SWCNT/mesh membranes with n-type thermoelectric properties, as well as p, nSWCNT/mesh thermoelectric power generation by combining the two. We created a machine and evaluated its power generation performance. As a result of evaluating the power generation performance, we were able to obtain an output voltage of 21 mV and a maximum power of 380 nW at a temperature difference of 150 K.

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Numerical acoustic analysis methods using the immersed boundary method can simulate the acoustic characteristics of structures with curved or sloping surfaces using cubic cells by providing estimates obtained from the boundary conditions on a cubic grid in the vicinity of the object boundary. Numerical analysis is possible even when the boundaries of the object and the lattice do not coincide, which has the advantage of allowing simulation when the object is moving. The numerical accuracy of the immersed boundary method when applied to acoustic analysis has not been fully investigated. In this paper, we investigate the accuracy of the immersed boundary method by numerically simulating the case where a cylinder is placed in a two-dimensional sound field. The directional characteristics of sound pressure and error rate as well as the root-mean-square error rate were calculated. The numerical results using the immersed boundary method showed almost the same characteristics as the analytical solution. Under the conditions of this paper, the calculation accuracy was found to be equivalent to that of the numerical results using the cubic grid. In the future, we plan to investigate the possibility of improving the accuracy of the difference scheme.

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The purpose of this study was to apply the EEG to BMI in order to realize appropriate control of the classification of subjects' intentions. The recorded EEGs were additive averaged and then compared with the EEGs of the left and right legs. The EEG recordings were additionally averaged, followed by ANOVA and multiple comparisons based on RP peaks, and classification of movement conditions using LSTM. The additive averaging revealed typical RP waveforms. Significant differences in the peak amplitude of RP were observed between the movement conditions at the frontal lobe measurement site. The mean values were larger in the order of condition I, M, and S, and the confidence intervals differed among the stimulus conditions. Furthermore, although the dominant foot of all subjects was the right, the mean value was larger for the left foot. Since the prefrontal cortex measures judgment and thinking, the mean value was also larger in the condition with stronger prefrontal cortex activity, suggesting a significant difference. LSTM was able to classify between conditions with high accuracy, 97.0% accuracy and 0.11% loss in the final value.

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Global warming has been progressing in recent years due to an increase in the concentration of carbon dioxide in the atmosphere. As a solution to this problem, the generation of methane from carbon dioxide by the Sabatier reaction is being considered. Since methane is the main component of city gas, existing infrastructure can be used with simple repairs. In our previous study, it was found that methane can be generated without any external heating upon ball-milling with LaNi₅ alloy powder. However, the ball-milling induced phase separation into La-compounds and metallic Ni, suggesting that the LaNi₅ actedioned as a catalyst precursor. It was also suggested that the release of atomic hydrogen affected methanation. Herein, we investigated the influence of atomic hydrogen on the mechanochemical methanation using Mg₂Ni hydrogen storage alloy in a vibratory ball-milling apparatus. Mg₂NiH_x and Mg₂NiD_y were used as starting materials, and the gas atmosphere in the vial was controlled by H₂ + CO₂ or D₂ + CO₂ to investigate possible kinetic isotope effect (KIE). The result indicated that the KIE was not observed, suggesting that the hydrogen supply is not the rate determining step in the mechanochemical methanation process.

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Concentrations of volatile organic compounds (VOCs) in exhaled and transdermal gases are changed depending on disease and metabolic states. Imaging of spatial distribution of transdermal VOCs at specific sites enables the identification of areas of high degree of emission. Furthermore, evaluation of VOC release dynamics is expected to have applications in simple and non-invasive metabolic assessment and disease screening. We developed a biofluorometric ethanol imaging system (sniff-cam) using the oxidation reaction of alcohol dehydrogenase (ADH). The sniff-cam was composed of an ADH-immobilized mesh, a UV-LED sheet, and a sensitive CCD camera to image the fluorescence intensity (ex: 340 nm, fl: 490 nm) of reduced nicotinamide adenine nucleotide (NADH), a coenzyme produced by the oxidizing ethanol catalyzed by ADH. The performance of the system was evaluated by measuring various concentrations of standard gaseous ethanol (EtOH), and a quantitative range of 0.05-10 ppm-v was obtained, which enables transdermal EtOH gas concentration measurement. The system also made it possible to visualize the 2D distribution of EtOH gas concentration in the hand and arm after drinking alcohol, and to study the appropriate sites for monitoring alcohol metabolism.

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