Study on the Use of Small Multi-Copter (UAV) in Agriculture

Poster Presentatio

Convolutional neural network (CNNs) based image diagnosis for failure analysis of power devices

An image diagnosis by deep learning was applied to failure analysis of power devices. A series of images during a process to failure by power cycling test was used for this method. The images were obtained by a scanning acoustic microscopy of our real-time monitoring system. An image classifier was designed based on a convolutional neural network (CNNs). A developed classifier successfully diagnosed input image into a normal device and an abnormal device. The accuracy of classification was improved by introducing a pre-training and an overlapping pooling into the system. A technique to extract a feature related a failure is essential for the failure analysis based on the real-time monitoring and the deep learning is one likely candidate for it

Crescent-Shaped Molecular Outflow from the Intermediate-mass Protostar DK Cha Revealed by ALMA

We report on an Atacama Large Millimeter/submillimeter Array (ALMA) study of the Class I or II intermediate-mass protostar DK Cha in the Chamaeleon II region. The 12CO (J=2-1) images have an angular resolution of ~1'' (~250 au) and show high-velocity blueshifted (>70 km s-1) and redshifted (>50 km s-1) emissions which have 3000 au scale crescent-shaped structures around the protostellar disk traced in the 1.3mm continuum. Because the high-velocity components of the CO emission are associated with the protostar, we concluded that the emission traces the pole-on outflow. The blueshifted outflow lobe has a clear layered velocity gradient with a higher velocity component located on the inner side of the crescent shape, which can be explained by a model of an outflow with a higher velocity in the inner radii. Based on the directly driven outflow scenario, we estimated the driving radii from the observed outflow velocities and found that the driving region extends over two orders of magnitude. The 13CO emission traces a complex envelope structure with arc-like substructures with lengths of ~1000au. We identified the arc-like structures as streamers because they appear to be connected to a rotating infalling envelope. DK Cha is useful for understanding characteristics that are visible by looking at nearly face-on configurations of young protostellar systems, providing an alternative perspective for studying the star-formation process.Comment: Accepted for publication in ApJ. 12 pages, 5 figure

Ring Gap Structure around Class I Protostar WL 17

WL 17 is a Class I object and was considered to have a ring-hole structure. We analyzed the structure around WL 17 to investigate the detailed properties of WL 17. We used ALMA archival data, which have a higher angular resolution than previous observations. We investigated the WL 17 system with the 1.3 mm dust continuum and 12CO and C18O (J = 2-1) line emissions. The dust continuum emission showed a clear ring structure with inner and outer edges of ~11 and ~21 au, respectively. In addition, we detected an inner disk of < 5 au radius enclosing the central star within the ring, the first observation of this structure. Thus, WL 17 has a ring-gap structure, not a ring-hole structure. We did not detect any marked emission in either the gap or inner disk, indicating that there is no sign of a planet, circumplanetary disk, or binary companion. We identified the base of both blue-shifted and red-shifted outflows based on the 12CO emission, which is clearly associated with the disk around WL 17. The outflow mass ejection rate is ~3.6x10^-7 Msun yr-1 and the dynamical timescale is as short as ~ 10^4 yr. The C18O emission showed that an inhomogeneous infalling envelope, which can induce episodic mass accretion, is distributed in the region within ~1000 au from the central protostar. With these new findings, we can constrain the planet formation and dust growth scenarios in the accretion phase of star formation.Comment: 22 pages, 9 figures, Accepted for publication in the Astrophysical Journa

An Extremely Young Protostellar Core, MMS 1/ OMC-3: Episodic Mass Ejection History Traced by the Micro SiO Jet

We present ${\sim}0.2$ arcsec ($\sim$80 au) resolution observations of the CO (2-1) and SiO (5-4) lines made with the Atacama large millimeter/submillimeter array toward an extremely young intermediate-mass protostellar source (t$_{\rm dyn}<$1000 years), MMS 1 located in the Orion Molecular Cloud-3 region. We have successfully imaged a very compact CO molecular outflow associated with MMS 1, having deprojected lobe sizes of $\sim$18000 au (red-shifted lobe) and $\sim$35000 au (blue-shifted lobe). We have also detected an extremely compact ($\lesssim$1000 au) and collimated SiO protostellar jet within the CO outflow. The maximum deprojected jet speed is measured to be as high as 93 km s$^{-1}$. The SiO jet wiggles and displays a chain of knots. Our detection of the molecular outflow and jet is the first direct evidence that MMS 1 already hosts a protostar. The position-velocity diagram obtained from the SiO emission shows two distinct structures: (i) bow-shocks associated with the tips of the outflow, and (ii) a collimated jet, showing the jet velocities linearly increasing with the distance from the driving source. Comparisons between the observations and numerical simulations quantitatively share similarities such as multiple-mass ejection events within the jet and Hubble-like flow associated with each mass ejection event. Finally, while there is a weak flux decline seen in the 850 $\mu$m light curve obtained with JCMT/SCUBA 2 toward MMS 1, no dramatic flux change events are detected. This suggests that there has not been a clear burst event within the last 8 years.Comment: 19 pages, 9 figures, Accepted for publication in Ap