44 research outputs found
Multi log-normal density structure in Cygnus-X molecular clouds: A fitting for N-PDF without power-law
We studied the H column density probability distribution function (N-PDF)
based on molecular emission lines using the Nobeyama 45-m Cygnus X CO survey
data. Using the DENDROGRAM and SCIMES algorithms, we identified 124 molecular
clouds in the CO data. From these identified molecular clouds, an N-PDF
was constructed for 11 molecular clouds with an extent of more than 0.4
deg. From the fitting of the N-PDF, we found that the N-PDF could be
well-fitted with one or two log-normal distributions. These fitting results
provided an alternative density structure for molecular clouds from a
conventional picture. We investigated the column density, dense molecular cloud
cores, and radio continuum source distributions in each cloud and found that
the N-PDF shape was less correlated with the star-forming activity over a whole
cloud. Furthermore, we found that the log-normal N-PDF parameters obtained from
the fitting showed two impressive features. First, the log-normal distribution
at the low-density part had the same mean column density ( 10
cm) for almost all the molecular clouds. Second, the width of the
log-normal distribution tended to decrease with an increasing mean density of
the structures. These correlations suggest that the shape of the N-PDF reflects
the relationship between the density and turbulent structure of the whole
molecular cloud but is less affected by star-forming activities.Comment: 14 pages, 7 Figures, Accepted in MNRA
A review of electrostatic monitoring technology: The state of the art and future research directions
Electrostatic monitoring technology is a useful tool for monitoring and detecting component faults and degradation, which is necessary for system health management. It encompasses three key research areas: sensor technology; signal detection, processing and feature extraction; and verification experimentation. It has received considerable recent attention for condition monitoring due to its ability to provide warning information and non-obstructive measurements on-line. A number of papers in recent years have covered specific aspects of the technology, including sensor design optimization, sensor characteristic analysis, signal de-noising and practical applications of the technology. This paper provides a review of the recent research and of the development of electrostatic monitoring technology, with a primary emphasis on its application for the aero-engine gas path. The paper also presents a summary of some of the current applications of electrostatic monitoring technology in other industries, before concluding with a brief discussion of the current research situation and possible future challenges and research gaps in this field. The aim of this paper is to promote further research into this promising technology by increasing awareness of both the potential benefits of the technology and the current research gaps
Numerical investigation of electrostatic effect on particle behavior in a 90 degrees bend
Ammonia mapping observations toward the Galactic massive star-forming region Sh 2-255 and Sh 2-257
We performed NH and mapping observations
toward the Galactic massive star-forming region Sh 2-255 and Sh 2-257 using the
Nobeyama 45-m telescope as a part of the KAGONMA (KAgoshima Galactic Object
survey with the Nobeyama 45-metre telescope by Mapping in Ammonia lines)
project. NH (1,1) has an intensity peak at the cluster S255 N, is
distributed over 3 pc 2 pc and is located between two HII regions. The
kinetic temperature derived from the NH ratio was K
near the massive cluster S255 IR. These clusters also show emission with a
large line width of 3-4 km s. Based on the reported data we
suggest that NH gas in these regions is affected by stellar feedback from
embedded YSO clusters in S255 IR and S255 N. We also detected NH (1,1)
emission in a region west of the main gas clump at the location of a
concentration of Class II YSOs adjacent to the HII regions Sh 2-254. The
presence of Class II YSOs implies 2 Myr of star formation, younger than
Sh 2-254 ( Myr), thus we suggest that star formation in the western
region could be influenced by the older HII region Sh 2-254.Comment: 20 pages, 8 figures, 3 tables, accepted for Publications of the
Astronomical Society of Japan (PASJ