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In this report, we proposed the installation of a conical phase adjuster (CPA) in a thermoacoustic prime mover as a method for reducing the onset temperature and investigated the effect of the installation position of a CPA on the onset temperature using stability analysis. The onset temperature of CPA also was investigated experimentally by changing the installation position of CPA. As a result, when CPA was installed at 1000 mm from the high-temperature end of the stack, the onset temperature was 195 K lower than the onset temperature without CPA, that is, the installation of the CPA in a loop-tube-type thermoacoustic prime mover reduced the onset temperature by 29%. Comparing onset temperatures of the PA had installed in a system, CPA is considered to have the same effect as a PA because the onset temperature tendency of the CPA to reduce at the installation position agrees with that of the PA. [ABSTRACT FROM AUTHOR]

The influence of an external sound applied to a loop-tube type thermoacoustic system on the energy conversion efficiency is experimentally examined. The investigation is carried out by studying the effect of a loudspeaker (SP) set as an external sound source. As a result, it is found that the location of the SP affects the sound field in the system and that the amount of energy generated increases or decreases. The increasing or decreasing effect differs depending on the location of the SP. Furthermore, it is confirmed that, provided the SP is located near the particle velocity node, the sound energy can be increased by more than the input power to the SP without changing the sound field in the tube. From these results it can be confirmed that, similar to a straight-tube type thermoacoustic system, the energy conversion efficiency can be enhanced by locating the SP at a suitable position even in a loop-tube type system without end surfaces. [ABSTRACT FROM AUTHOR]

We report the performance of a prototype 29 m long loop-tube-type thermoacoustic prime mover. The phase adjuster (PA) that succeeded in low-temperature oscillation was examined for the aforementioned prototype. The onset temperature when PA length and PA position were changed was calculated using stability analysis. The onset temperature was found to be 153 °C. Using the calculation results, a prototype that succeeded in oscillating at an onset temperature of 155 °C was developed. These results indicate that the thermoacoustic system was successfully enlarged. This will promote practical application of a large system that converts waste heat to effective energy. [ABSTRACT FROM AUTHOR]

Energy conversion which takes place in a stack wetted with water is investigated. To clarify the discussion, two cases for working fluid of only air and air containing water vapor are compared. As a result, three conclusions are obtained: 1. In the case of air only, energy generation depends on temperature gradient; 2. In the case of a mixture of water vapor and air, the energy generation depends on the number-density ratio; 3. The energy generation due to water vapor is around 15 times that due to air. These conclusions are thought to be useful for designing a thermoacoustic system capable of low-temperature driving which uses the stack wetted with water. [ABSTRACT FROM AUTHOR]

Sound field control to suppress resonance transition from fundamental mode to secondary mode, that was a significant problem in coaxial-type thermoacoustic system, is examined by modifying the acoustic tube. The experiments are carried out by applying a phase adjuster (PA) or an expanding phase adjuster (EPA) which has been used for a different thermoacoustic system. The position for installing PA or EPA is determined based on the experimental results for the sound field. It is demonstrated that the suppression effect of the secondary mode is enhanced as the thickness of PA or the inner diameter of EPA increases and PA and EPA then affect the phase of the sound field in the tube. Furthermore, an advantage for actual application that the phase at the setting position of HP approaches the phase of traveling wave and the system performance is improved by the increased traveling wave component is also confirmed. [ABSTRACT FROM AUTHOR]

For the practical realization of the loop-tube type thermoacoustic system, a technique of heat phase adjuster (HPA) has previously been presented for controlling the resonance mode and improving the energy conversion efficiency by locally supplying a heat input. In order to theoretically examine the mechanism of such ability of HPA from an acoustic view point, the physical model for HPA is presented. In this model, the sound field of each resonance mode changing with the setting position of HPA as well as the temperature of HPA is theoretically discussed. As a result, it is found that HPA controls the resonance mode by making only the sound wave of a specific resonance mode propagate in the positive direction and furthermore the energy conversion efficiency changes with the phase shift of the incident wave from the reflected wave dependent on the temperature of HPA. [ABSTRACT FROM AUTHOR]

The technique to control the resonance mode necessary for enhancing the energy conversion efficiency of thermoacoustic system is discussed. A standing-wave type thermoacoustic system is set in the condition that the self-excited vibration with 3/2 wavelength of the total tube length takes place by adjusting the position of the stack. The sound wave of the fundamental mode is then externally superposed on the sound wave excited in the system. As a result, the resonance of the system is shifted to the fundamental mode from the higher mode. Furthermore, the resonance control is supposed to be realized by the reason that thickness of the viscous boundary layer is reduced and that the self-excited vibration is enabled at the lower entropy generation comparing with the higher-mode resonance. These results suggest that the technique to use the superposing sound wave is valid for enhancing the energy conversion efficiency by the resonance control. [ABSTRACT FROM AUTHOR]

A coaxial-type thermoacoustic system (coaxial type) has the potential to solve the problem of the practical use of downsizing while keeping high efficiency. However, when a prime mover (PM) is set close to the antinode of the sound pressure distribution, the performance of the coaxial type is degraded due to the shift of the resonance mode. In the present paper, resonance control is experimentally investigated to improve the performance of the coaxial type. On the basis of sound pressure distributions, the setting position to suppress the excitation of the secondary mode is predicted and resonance mode control with an additional PM is attempted. As a result, resonance control is successfully attained and the sound pressure is enhanced compared with the system with a single PM. The oscillation temperature is also lowered by more than 200 °C, and an improvement of performance is confirmed. [ABSTRACT FROM AUTHOR]

In the present paper, the influence of the temperature distribution in the stack on the work flow generation is experimentally investigated. To actively change the temperature distribution in the stack, the central heating method to settle the heat source on the center as well as one end of the stack is employed. As a result, in the case that the central heating method is used, the work flow generation increases by 1.6 times comparing with the method to heat only one end. The work flow generation is deemed to increase because the temperature gradient is formed on the side of the cold end which is the region with a large effective thermal expansion coefficient. From the above discussion, the central heating method is suggested to be valid for increasing the energy generation. [ABSTRACT FROM AUTHOR]

The performance of a new structure plasma display panel (PDP) cell with counter sustain electrodes was diagnosed by optical emission and laser absorption spectroscopic measurements of the spatiotemporal behaviours of the microplasma. Two different types of panels were prepared: one with sustain electrodes only and the other with additional data and auxiliary electrodes on the rear and front plates. By using cells of the former type, the basic performance was measured as the dependences on the Xe concentration in Ne, the total pressure and the applied sustain voltage. It was seen that a higher Xe concentration was advantageous for the luminous efficiency although the required minimum sustain voltage became larger. By using the latter type of cell, the effects of driving schemes were investigated by varying the applied potentials onto the auxiliary and data electrodes. It was found that the role of the auxiliary electrode is remarkable; the discharge expands largely in the cell when the voltage and the width of the pulses applied to the auxiliary electrode are optimized to be 200 V and 0.3 µs, respectively, while the data electrode is grounded. The production efficiency of Xe atoms in the metastable (1s5) and resonance (1s4) states was derived from the measured absolute densities normalized by the input power per cell and the decay rates of those densities. The vacuum ultraviolet emission efficiency estimated from the results was compared between the tested conditions, and a noticeable improvement was recognized in the optimized condition, about 40% larger than a conventional driving condition without additional pulses. It was also seen that this cell structure is potentially superior in luminous efficiency to the conventional coplanar structure currently used in commercial PDPs. [ABSTRACT FROM AUTHOR]

Very few detections have been made of optical flashes contemporaneous with prompt high-energy emission from a gamma-ray burst (GRB). In this work, we present and analyze light curves of GRB-associated optical flashes and afterglows from the Transiting Exoplanet Survey Satellite (TESS). Our sample consists of eight GRBs with arcsecond-level localizations from the X-Ray Telescope on board the Neil Gehrels Swift Observatory (Swift). For each burst, we characterize the prompt optical emission and any observed afterglow, and constrain physical parameters for four of these bursts using their TESS light curves. This work also presents a straightforward method to correct for TESS's cosmic-ray mitigation strategy on 20 s timescales, which allows us to estimate the "true" brightness of optical flashes associated with prompt GRB emission. We also highlight TESS's continuous wide-field monitoring capability, which provides an efficient means of identifying optical emission from GRBs and characterizing early time afterglow light curves. Based on empirical detection rates from Swift and the Fermi Gamma-ray Space Telescope, up to 10 GRBs per year may fall within the contemporaneous TESS field of view. [ABSTRACT FROM AUTHOR]

The afterglows of gamma-ray bursts are believed to have originated from a relativistic jet, which is driven by the merger of compact binary objects or the core collapse of massive stars. Some of their jets may consist of two components: a faster (but narrower) jet and a slower (but wider) jet. The light curves produced by the interaction between the two-component jet and the surrounding medium typically exhibit a chromatic break in multiple bands. For GRB 191221B, the optical light curve of the afterglow exhibits a plateau from 33 to 143 s, followed by a steeper decay that is consistent with the characteristics of reverse shock from an arbitrarily magnetized ejecta. The flattening at ∼10 ks exhibits chromaticity relative to the X-ray afterglow. We propose that the two-component jet scenario can explain this observational result: For the X-ray afterglow, the narrow jet forward shock is dominated until ∼10 ks, and then both the narrow and wide components contribute comparable flux from the forward shock. For the optical afterglow, the first 2 ks is dominated by the narrow jet reverse shock emission (the plateau from 33 to 143 s is due to the jet being magnetized). Between 2 and 10 ks, the forward shock of the narrow jet dominates the optical afterglow, then transitions to wide component forward shock dominance, causing a chromatic plateau. For radio afterglow, the data are only presented after 105 s, which is dominated by the wide jet forward shock emission. [ABSTRACT FROM AUTHOR]

In a traveling-wave type thermoacoustic system using a heat phase adjuster (HPA), the sound field control by the local thermal input to the acoustic tube is examined. Focusing the attention on the acoustic boundary conditions produced by a HPA, when the sound pulse is emitted from a loudspeaker, the reflection at the setting position of the HPA is observed. As a result, it is suggested that the reflection phenomenon which takes place corresponding to the operation condition of HPA is a contributing factor to control the sound field in the stack. Regarding the influence of a prime mover (PM) stack and a HPA on the sound field in the tube, it is found that, while PM stack is dominant at low electric power driving of a HPA, the HPA becomes conversely dominant at high-power driving. From this result, a possibility to dynamically control the energy conversion quantity in the stack by using a HPA is shown. [ABSTRACT FROM AUTHOR]

With the aim of realizing low-temperature driving of a thermoacoustic system, an experiment focused on the temperature in the stack is carried out. The temperatures at both ends of the stack are set to be similar in two cases: the wet condition (with the addition of moisture) and the dry condition (without the addition of moisture). Comparing the measured temperature distributions over time, it is found that the temperature gradient that exists near the hot end gradually shifts toward the cold end as the internal temperature rises, particularly in the wet condition. It is consequently confirmed that a temperature field that can convert heat to sound is formed at the cold end with large latent heat that contributes significantly to the enhancement of acoustic power generation in the stack. [ABSTRACT FROM AUTHOR]

To effectively use the whole area in a stack for energy conversion, the formation of a uniform temperature gradient over the whole area in the stack is necessary. For the temperature gradient formation, a method to heat the intermediate positions in the stack with heaters is proposed. In this paper, the relation between the heating position of the stack and the quantity of the work flow generation is experimentally investigated. As a result, the work flow generation increased and the energy conversion efficiency improved due to the effect of heating the intermediate position in the stack. In addition, the work flow generation increases most significantly in the case where the whole area of the stack has a uniform temperature gradient. Therefore, it is assumed to be preferable for stack design that the temperature gradient is uniform over the whole area in the stack. [ABSTRACT FROM AUTHOR]

We have discussed the Dirac equation in Schwarzschild spacetime using pseudo-supersymmetric quantum mechanics and have obtained the partner Hamiltonian of the initial Hamiltonian operator. We demonstrate that the partner metric tensors, corresponding to these Hamiltonians, can be derived using the intertwining relations inherent in pseudo-supersymmetric approaches. We have seen that the Schwarzschild metric may be expanded into Schwarzschild–Tangherlini metric using the aspects of pseudo-supersymmetry. Furthermore, we have derived approximate solutions for the radial component within the framework of N = 2 supersymmetry with the corresponding radial potential graphs presented. Subsequently, our discussion extends to the quasinormal modes, focusing particularly on the asymptotic limits as r approaches ± ∞ . [ABSTRACT FROM AUTHOR]

Objective. X-ray microangiography provides detailed information on the internal structure and function of a biological subject. Its ability to evaluate the microvasculature of small animals is useful for acquiring basic and clinical medical knowledge. The following three conditions are necessary to attain detailed knowledge of biological functions: (1) high temporal resolution with sufficient x-ray intensity, (2) high spatial resolution, and (3) a wide field of view. Because synchrotron radiation microangiography systems provide high sapatial resolution and high temporal resolution as a result of their high x-ray intensity, such systems have been developed at various synchrotron radiation facilities, starting with the photon factory, leading to numerous medical discoveries. However, the three aforementioned functions are incompatible with the use of synchrotron radiation because the x-ray intensity decreases when a wide field of view is obtained. To overcome these problems, we developed a new x-ray optical system for microangiography in rats using synchrotron radiation x-rays. Approach. Instead of using monochromatic synchrotron radiation x-rays with a conventional double-crystal monochromator, we used white synchrotron radiation x-rays and an asymmetric Si crystal to simultaneously monochromatize the beam and widen the field of view. Main results. The intensity profile and spatial resolution of the x-ray images were then evaluated. The proposed x-ray optics increased the x-ray intensity and beam width by factors of 1.3 and 2.7, respectively, compared with those of conventional monochromatic x-rays. In addition, in vivo studies on microangiography in rats were performed to confirm that the images had sufficient intensity, spatial resolution, and field of view. One of a series of images taken at 50 ms frame−1 was shown as an example. Significance. This x-ray optics provides sufficient x-ray intensity, high spatial resolution, and a wide field of view. This technique is expected providing new insights into the evaluation of the vascular system. [ABSTRACT FROM AUTHOR]

We report the results of Atacama Large Millimeter/submillimeter Array (ALMA) 1–2 kpc resolution, three rotational transition-line (J = 2–1, J = 3–2, and J = 4–3) observations of multiple dense molecular gas tracers (HCN, HCO+, and HNC) for 10 nearby (ultra)luminous infrared galaxies ((U)LIRGs). Following the matching of beam sizes to 1–2 kpc for each (U)LIRG, the high- J -to-low- J transition-line flux ratios of each molecule and the emission-line flux ratios of different molecules at each J transition are derived. We conduct RADEX non-LTE model calculations and find that, under a wide range of gas density and kinetic temperature, the observed HCN-to-HCO+ flux ratios in the overall (U)LIRGs are naturally reproduced with enhanced HCN abundance compared to HCO+. Thereafter, molecular gas properties are constrained primarily through the use of HCN and HCO+ data and the adoption of fiducial values for the HCO+ column density and HCN-to-HCO+ abundance ratio. We quantitatively confirm the following: (i) molecular gas at the (U)LIRGs' nuclei is dense (≳103–4 cm−3) and warm (≳100 K), (ii) the molecular gas density and temperature in nine ULIRGs' nuclei are significantly higher than those of one LIRG's nucleus, (iii) molecular gas in starburst-dominated sources tends to be less dense and cooler than ULIRGs with luminous AGN signatures. For six selected sources, we also apply a Bayesian approach by freeing all parameters and support the above main results. Our ALMA 1–2 kpc resolution, multiple transition-line data of multiple molecules are a very powerful tool for scrutinizing the properties of molecular gas concentrated around luminous energy sources in nearby (U)LIRGs' nuclei. [ABSTRACT FROM AUTHOR]

We investigated a thermoacoustic system to achieve low-temperature driving. Inputting heat to the stack causes unwanted heat flows through the tube wall and the working gas, i.e., heat leak. The heat leak generates the temperature distribution along the tube from the high-temperature side of the stack to the closed end. The section where the temperature distribution is formed is called the thermal buffer tube. In this study, we focused on the temperature distribution of the thermal buffer tube. We measured the temperature distribution of the thermal buffer tube and made a comparison between the onset temperature obtained from the experiment and the critical temperature obtained by stability analysis. The difference in the results was 6 °C. The analytical critical temperature changed significantly with the assumed shape of the temperature distribution in the thermal buffer tube. [ABSTRACT FROM AUTHOR]

We report two types of site-selective metal deposition methods based on colloidal crystal templating. We discuss in particular the controllability of the morphology and crystallinity of Au nanodots depending of the choice of method. [ABSTRACT FROM AUTHOR]

The itinerant 4 d ferromagnetic perovskite SrRuO3 [bulk Curie temperature (T C)Â =Â 165 K] has been studied extensively for many decades because of the unique nature of its ferromagnetism, metallicity, chemical stability, and compatibility with other perovskite-structured oxides. Recently, SrRuO3 has been gathering renewed interest as a magnetic Weyl semimetal and a two-dimensional ferromagnetic system. Ultra-high-quality SrRuO3 film growth techniques, combining oxide molecular beam epitaxy technology and a statistical machine learning method, have revealed new physics and physical properties of SrRuO3 as a magnetic Weyl semimetal, such as quantum transport of Weyl fermions and high-mobility two-dimensional carriers from surface Fermi arcs. This review summarizes the methods of growing ultra-high-quality SrRuO3 films and the novel physics found in them. In addition, progress in crystal structure analyses and the electrical and magnetic properties of SrRuO3 over the last decade will also be discussed. [ABSTRACT FROM AUTHOR]

We investigated the vibrational temperature of molecular nitrogen in the downstream of helicon-wave excited helium and argon-based plasmas. It was confirmed by optical emission spectroscopy that the major part of the helium plasma was at a recombining state and it had an ultralow electron temperature of approximately 0.1Â eV. In spite of the ultralow electron temperature, the vibrational temperature of molecular nitrogen, which was added into the helium plasma, was higher than that in the argon-based plasma at an ionizing state with an electron temperature of 1.7Â eV. According to the relationship between the rate coefficient of electron impact vibrational excitation and the electron temperature, the higher vibrational temperature in the helium plasma is not attributable to the more efficient vibrational excitation. Therefore, the higher vibrational temperature is owing to the less efficient destruction of vibrational excited states in the helium plasma with the ultralow electron temperature. [ABSTRACT FROM AUTHOR]

Both Galactic and extragalactic studies of star formation suggest that stars form directly from dense molecular gas. To trace such high volume density gas, HCN and HCO+ J = 1 â†' 0 have been widely used for their high dipole moments, relatively high abundances, and often being the strongest lines after CO. However, HCN and HCO+ J = 1 â†' 0 emission could arguably be dominated by the gas components at low volume densities. The HCN J = 2 â†' 1 and HCO+ J = 2 â†' 1 transitions, with more suitable critical densities (1.6 Ă— 106 and 2.8 Ă— 105 cmâˆ'3) and excitation requirements, would trace typical dense gas closely related to star formation. Here we report new observations of HCN J = 2 â†' 1 and HCO+ J = 2 â†' 1 toward 17 nearby infrared-bright galaxies with the APEX 12 m telescope. The correlation slopes between the luminosities of HCN J = 2 â†' 1 and HCO+ J = 2 â†' 1 and total infrared emission are 1.03 ± 0.05 and 1.00 ± 0.05, respectively. The correlations of their surface densities, normalized with the area of radio/submillimeter continuum, show even tighter relations (slopes: 0.99 ± 0.03 and 1.02 ± 0.03). The eight active galactic nucleus (AGN)â€"dominated galaxies show no significant difference from the 11 star-formationâ€"dominated galaxies in the above relations. The average HCN/HCO+ ratios are 1.15 ± 0.26 and 0.98 ± 0.42 for AGN- and star-formationâ€"dominated galaxies, respectively, without obvious dependencies on infrared luminosity, dust temperature, or infrared pumping. The Magellanic Clouds roughly follow the same correlations, expanding to 8 orders of magnitude. On the other hand, ultraluminous infrared galaxies with AGNs systematically lie above the correlations, indicating potential biases introduced by AGNs. [ABSTRACT FROM AUTHOR]

This paper is aimed at revealing origins of spurious resonances and Q deterioration of thickness shear bulk acoustic resonators (TSBARs) with the edge ratio W x / W y of rectangular electrodes by a field analyses. Here, W x and W y are distances between side edges giving the broadband and standard piston designs, respectively. The field distribution is calculated by applying traceback technique to the full three dimensional finite element method based on hierarchical cascading technique, its variation with the edge ratio is studied in detail, with assistance of the wavenumber domain analysis. The result indicates that the mode conversion and the leakage occur at the bump region causing Q reduction, and generated hybrid modes causing spurious resonances. The former is significant when W x / W y is large and the latter becomes obvious when W x / W y is small. [ABSTRACT FROM AUTHOR]