Publications by authors named "Yoshihiro Deguchi"

Segregation monitoring plays an essential role in the quality control of steels, and laser-induced breakdown spectroscopy (LIBS) can be employed as a diagnostic tool in this process for elemental microanalysis. In this study, we constructed an ultrafast LIBS system employing a 1.2 kHz repetition-rate picosecond laser (ps-laser) to achieve high-throughput analysis of steel segregation with a spatial resolution of 1 μm.

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The single parameter detection of temperature (HO) is no longer sufficient for the absorption combustion diagnosis. There is a huge demand for simultaneous computed tomography (CT) diagnosis of multi-parameters. This paper studied CO and NO, two representative combustion products based on tunable diode laser absorption spectroscopy (TDLAS) and ultraviolet absorption spectroscopy (UVAS).

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Background: Fast and accurate classification of steel can effectively improve industrial production efficiency. In recent years, the use of laser-induced breakdown spectroscopy (LIBS) in conjunction with other techniques for material classification has been developing. Plasma Acoustic Emission Signal (PAES) is a type of modal information separate from spectra that is detected using LIBS, and it can reflect some of the sample's physicochemical information.

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Tunable diode laser absorption spectroscopy (TDLAS) is a widely used diagnostic technique due to its high sensitivity, fast response, low cost, and other merits. Hydrocarbon detection is a field of great interest in the application of tunable diode lasers as hydrocarbons are fundamental molecules in many industrial processes. Many tunable diode lasers are only suitable for single species detection due to the short scanning range and in real situations.

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The long-short double-pulse laser-induced breakdown spectroscopy (LS-DP-LIBS) method was applied to qualitative and quantitative analyses of underwater steel samples to improve the detection ability of underwater measurement. The stable plasma intensity and discrete emission lines were detected using LS-DP-LIBS when comparing the measured results of single-pulse LIBS (SP-LIBS) and LS-DP-LIBS. The long pulse produces a cavitation bubble without plasma, and the short pulse induces the plasma of steel samples within the bubble.

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Cell-free and concentrated ascites reinfusion therapy (CART) is an effective therapy for refractory ascites. However, CART is difficult to perform as ascites filtration and concentration is a complicated procedure. Moreover, the procedure requires the constant assistance of a clinical engineer or/and the use of an expensive equipment for the multi-purpose blood processing.

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Tunable diode laser absorption spectroscopy (TDLAS) technology is a developing method for temperature and species concentration measurements with the features of non-contact, high precision, high sensitivity, etc. The difficulty of two-dimensional (2D) temperature measurement in actual combustors has not yet been solved because of pressure broadening of absorption spectra, optical accessibility, etc. In this study, the combination of computed tomography (CT) and TDLAS with a wide scanning laser at 1335-1375 nm has been applied to a combustor for 2D temperature measurement in high temperature of 300-2000 K and high pressure of 0.

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A long-short double pulse laser-induced breakdown spectroscopy (long-short DP-LIBS) method was employed to improve the analytical performance of LIBS for the measurement of manganese in steel samples. The long pulse with a duration of 60 μs was generated using a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser which was operated at free-running (FR) mode. To investigate the detection ability without sample preparation, the steel washers were tested using single-pulse LIBS (SP-LIBS) and long-short DP-LIBS, respectively.

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Collinear long and short dual-pulse laser-induced breakdown spectroscopy (DP-LIBS) was employed to clarify the emission characteristics from laser-induced plasma. The plasma was sustained and became stable by the long pulse-width laser with the pulse width of 60 μs under free running (FR) conditions as an external energy source. Comparing the measurement results of stainless steel in air using single-pulse LIBS (SP-LIBS) and DP-LIBS, the emission intensity was markedly enhanced using DP-LIBS.

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The rapid and precise element measurement of trace species, such as mercury, iodine, strontium, cesium, etc. is imperative for various applications, especially for industrial needs. The elements mercury and iodine were measured by two detection methods for comparison of the corresponding detection features.

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Laser-induced breakdown spectroscopy (LIBS) technology is an appealing technique compared with many other types of elemental analysis because of the fast response, high sensitivity, real-time, and noncontact features. One of the challenging targets of LIBS is the enhancement of the detection limit. In this study, the detection limit of gas-phase LIBS analysis has been improved by controlling the pressure and laser pulse width.

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LI-IT-TOFMS (laser ionization/ion-trap storage/time-of-flight mass spectrometry) is expected to be a powerful tool for environmental monitoring. In the research reported here, real-time LI-IT-TOFMS measurements were carried out on gaseous 2-4 chlorinated PCBs in order to evaluate the applicability of an environmental monitoring method. With respect to ion-trap storage for PCBs, we found that the effect was due to the driving RF voltage on the ring electrode in the ion trap.

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Polychlorinated biphenyls (PCBs) are hazardous compounds for which there are few methods involving real-time measurement. Recently, the development of the pulsed-laser technique has enabled us to measure aromatic hydrocarbons quite rapidly. In particular, the LI-TOFMS (laser ionization time of flight mass spectrometry) technique is expected to be a powerful method for on-line, selective and sensitive measurements.

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The study demonstrates the applicability of laser ionization time-of-flight mass spectrometry for real-time measurement of polychlorinated biphenyls (PCBs). Picosecond 266-nm laser light ionization reduced fragmentation and provided very high PCB detection sensitivity. This high sensitivity has advantages in terms of real-time monitoring capability as compared to the conventional GC-ECD or GC-MS methods, which require at least several days for the analysis of PCBs.

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A laser-induced breakdown spectroscopy (LIBS) technique has been applied for detection of unburned carbon in fly ash, and an automated LIBS unit has been developed and applied in a 1000-MW pulverized-coal-fired power plant for real-time measurement, specifically of unburned carbon in fly ash. Good agreement was found between measurement results from the LIBS method and those from the conventional method (Japanese Industrial Standard 8815), with a standard deviation of 0.27%.

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