369 research outputs found
FOURIER TRANSFORM MICROWAVE SPECTRA OF 1-PENTANETHIOL
Rotational spectra of the 1-pentanethiol (1-CSH) were observed using a Fourier transform microwave spectrometer. Eight sets of the 1-CSH were assigned by combined with the quantum chemical calculations. The four Sets 1-4 of {\it a}-type {\it R}-branch transitions of 1-CSH were observed in diluted Ar. Another four Sets 5-8 of {\it a}-type transition were observed near the four Sets 1-4 in diluted Ne instead of Ar. The Set 1 has the most intense spectrum and small splittings due to the torsional motion of the SH group and the internal rotation of the CH group of the {\it TTTg} conformer of the 1-CSH. In the case of 1-CSH there are four operations; the first generating operation is the relative orientation of CH groups around the C(5)HC(4)H-C(3)HC(2)HC(1)HSH axis, leading to {\it gauche} and {\it trans} conformers, {\it G} or {\it T}, the second is around C(3)-C(2) axis and the third is around C(2)-C(1) axis, leading to {\it gauche} and {\it trans} conformers, {\it G}, {\it G’} or {\it T}, and the fourth is around C(1)-SH also leading to {\it gauche} and {\it trans} orientations, {\it g}, {\it g’} or {\it t}. For Set 2, {\it a}-, {\it b}-, and {\it c}-type transitions were observed and assigned as to {\it TTGg’} conformer. Only {\it a}-type transitions of the Sets 3 and 4 were observed. The obtained rotational constants of the Sets 3 and 4 agreed with the calculated values of the {\it TGTg}/{\it TGTg’} and {\it GTTg}/{\it GTTg’}, respectively. Comparing the obtained rotational constants with the quantum chemical calculations, the Sets 5 and 6 were assigned as to be {\it TTTt} and {\it TTGg}, respectively. Similarly Sets 3, 7, 4 and 8 were assigned as {\it TGTg’}, {\it TGTg}, {\it GTTg} and {\it GTTg’}, respectively
Impulsive Breaking Wave Pressure Acting on Seawall Installed on Steep Slope Seabed and the Measures
Enhanced exchange anisotropy of Ni-Fe/Mn-Ni bilayers fabricated under the extremely clean sputtering process
Autonomous Navigation, Guidance and Control of Small Electric Helicopter
In this study, we design an autonomous navigation, guidance and control system for a small electric helicopter. Only small, light-weight, and inaccurate sensors can be used for the control of small helicopters because of the payload limitation. To overcome the problem of inaccurate sensors, a composite navigation system is designed. The designed navigation system enables us to precisely obtain the position and velocity of the helicopter. A guidance and control system is designed for stabilizing the helicopter at an arbitrary point in three-dimensional space. In particular, a novel and simple guidance system is designed using the combination of optimal control theory and quaternion kinematics. The designs of the study are validated experimentally, and the experimental results verify the efficiency of our navigation, guidance and control system for a small electric helicopter.ArticleINTERNATIONAL JOURNAL OF ADVANCED ROBOTIC SYSTEMS. 10:54 (2013)journal articl
Ecological and growth characteristics of trees after resumption of management in abandoned substitution forest in Japan
Since the 1950s, secondary (substitution) forests known as Satoyama woods have been abandoned due to changes in human lifestyle. The aim of this study was to investigate the relationships between human activity and substitution forests to better understand the traditional management required to prevent succession to evergreen forest. An objective was to identify the tree species, their numbers of trunks (NT), and the basal area (BA) (collectively, the stand density) in the woods today, half a century after people abandoned the substitution forests. Another goal was to compare, over a six-year period, the figures for total NT, BA, and the number of living, dead or fallen trunks between an abandoned substitution forest (a control plot) and a mown plot. NT decreased from 700 trunks/ha to 600 trunks/ha on the control, and from 600 trunks/ha to 400 trunks/ha on the mown plot at ground level over six years. The total BA increased annually on the control plot but decreased from 48m2/ha to 38m2/ha on the mown plot over six years. Many hydrophytes (Alnus japonica, etc.), Quercus serrata, and other trees species were found dead on the mown plots. All Quercus myrsinaefolia (evergreen trees) were still alive by the sixth year. These results demonstrate that the vegetation in these forests succeeded to Quercetum myrsinaefoliae, Tyoische Subass., which is therefore shown as the potential vegetation of succession over this timescale. If it is desired to maintain the traditional vegetation type, then the study suggests that it is necessary to manage the substitution forest. This is in order to prevent succession to evergreen forest and can be achieved by cutting Pleioblastus chino, climbing plants, and shade plants (evergreen trees)
Emplacement of penetrators into planetary surfaces
We present experimental data and a model for the low-velocity (subsonic, 0–1000 m/s) penetration of brittle materials by both solid and hollow (i.e., coring) penetrators. The experiments show that penetration is proportional to momentum/frontal area of the penetrator. Because of the buildup of a cap in front of blunt penetrators, the presence or absence of a streamlined or sharp front end usually has a negligible effect for impact into targets with strength. The model accurately predicts the dependence of penetration depth on the various parameters of the target-penetrator system, as well as the qualitative condition of the target material ingested by a corer. In particular, penetration depth is approximately inversely proportional to the static bearing strength of the target. The bulk density of the target material has only a small effect on penetration, whereas friction can be significant, especially at higher impact velocities, for consolidated materials. This trend is reversed for impacts into unconsolidated materials. The present results suggest that the depth of penetration is a good measure of the strength, but not the density, of a consolidated target. Both experiments and model results show that, if passage through the mouth of a coring penetrator requires initially porous target material to be compressed to <26% porosity, the sample collected by the corer will be highly fragmented. If the final porosity remains above 26%, then most materials, except cohesionless materials, such as dry sand, will be collected as a compressed slug of material
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