Propulsion performance optimization of “neighbour duct” by CFD

As one of measures against CO2 reduction regulation by EEDI, energy-saving device (ESD) has been widely used. As one of ESD, the authors developed "Neighbour Duct" which was a vertical-long-oval stern duct. Neighbour Duct generates thrust by harnessing flow along both sides of stern. By CFD, the geometric parameter of Neighbour Duct was optimized, and the principle of thrust generation was made clear. In order to verify the result of CFD, a series of model test was carried out at National Maritime Research Institute (NMRI), the thrust deduction factors of both CFD and model test results were good agreement. As Estimation of performance of actual ship based on the model test, BHP was reduced 4.4% by Neighbour Duct. In addition, 1-w only decreased by 1%. Therefore it was found that CO2 reduction effect would be obtained by Neibour Duct without changing the propeller or propeller design

The Change of Primary Students\u27 Attitude in Last 40 Years in Rural Northeast Thailand : A Comparative Analysis of 20 years-interval Questionnaire Surveys

Don Daeng village is located at the Chi River floodplain in Khon Kaen, rural area of Northeast Thailand. Three significant field surveys were conducted in last 40 years there. The first survey was conducted by MIZUNO Koichi, a Japanese sociologist, in 1964. The second integrated and interdisciplinary survey was conducted in 1981-83 by ISHII Yoneo, FUKUI Hayao, KUCHIBA Masuo, and younger research cooperators. The third survey has just completed by FUNAHASHI Kazuo and research cooperators in fiscal 2005. In last 40 years Don Daeng village has drastically changed form subsistence economy, then part-time farming-dominated village, and lastly to a suburban village that most villagers are commuting to work. The aim of this study is to analyze the set of questionnaire to Don Daeng, Don Noi primary/secondary school students on their attitude in the following items by grade and sex in 2004: 1) person or people they respect, 2) the intension of entering a higher-level school and to what level, 3) the intension of expected occupation and job, 4) favorite movies and characters. Furthermore, we also asked how often they go to Khon Kaen city. Total number of respondent is 53 primary grade-3 and -6 students, and 27 lower secondary students of grade-9. The main focus is how contemporary students feel about their village and future in the course of life with special reference to higher education. As the tentative results, the following four points are indicated: 1. Agriculture was the expected job in 1983 survey for the majority of students, but present situation has driven into urban life style and weakened the intension of being farmers 2. The rate of going to higher education increased and students\u27 behavior preference had been intended to move Bangkok directly, not Kohn Kaen or surrounding areas. 3. The background is the development of mass media in rural area and the introduction of urbanstyle in their student\u27s life. 4. The majority of students\u27 attitude had shifted into cash-income intended jobs or \u27white color\u27 interest

Wind- and Operation-Induced Vibration Measurements of the Main Reflector of the Nobeyama 45 m Radio Telescope

As deformations of the main reflector of a radio telescope directly affect the observations, the evaluation of the deformation is extremely important. Dynamic characteristics of the main reflector of the Nobeyama 45 m radio telescope, Japan, are measured under two conditions: The first is when the pointing observation is in operation, and the second is when the reflector is stationary and is subjected to wind loads when the observation is out of operation. Dynamic characteristics of the main reflector are measured using piezoelectric accelerometers. When the telescope is in operation, a vibration mode with one nodal line horizontally or vertically on the reflector is induced, depending on whether the reflector is moving in the azimuthal or elevational planes, whereas under windy conditions, vibration modes that have two to four nodal lines are simultaneously induced. The predominant mode is dependent on the direction of wind loads.Comment: Accepted for publication in Journal of Vibration Engineering & Technologie

Effects of Ti and Nb on the Nucleation of Primary Austenite in Hypoeutectic Cast Iron of Fe-C System

Experiments were conducted to observe how nucleation and growth of primary austenite (r) of Fe-C system cast iron change with the addition of titanium (Ti) and niobium (Nb), which form carbides by reacting with carbon (C) in the melt. The results obtained were discussed both from the structural observation of carbides and thermodynamics concerning the variation of the amount of carbides formed(TiCor NbC) and the elements dissolved in the melt during cooling. The atomic concentrations of Ti and Nb in the melt were nearly equal. The degree of undercooling before nucleation and the amount of nucleation (number of austenite grains) increase by increasing the Ti content. By increasing the Ti content the growth morphology of the primary r tends to become endogeneous, i.e. the nuclei formedover the whole area of the melt grow as equiaxed crystals. Nucleation and growth morphology are scarcely affected by the addition of Nb. Ti carbides are formed in sequence over the range from a high temperature, 1,500°C, to eutectic　temperature. Most of the Nb carbides are formed at considerably higher temeprature than liquidus and are scarcely formed at temperature near that of nucleation of the primary austenite. Consequently the amount of C atoms taken away by Ti from the melt at the liquidus is extremely larger than that by Nb. It was concluded that the factor governing the nucleation of r is not the carbides or their amount formed before the nucleation of r, but the action of the elements forming carbides while taking C out of the melt. The newly formed surfaces of the carbides are the most effective sites for nucleation, since that part is most enriched in Fe. It was also concluded that the addition of Nb hardly promotes the nucleation, because it takes little C atoms out of the melt at the nucleation temperature, while the addition of Ti promotes the nucleation by taking a large quantity of C atoms out of the melt at the nucleation temperature of the primary r

Characterization of sensitivity and responses of a 2-element prototype wavefront sensor for millimeter-wave adaptive optics attached to the Nobeyama 45 m telescope

We report the results of the performance characterization of a prototype wavefront sensor for millimetric adaptive optics (MAO) installed on the Nobeyama 45 m radio telescope. MAO is a key component to realize a future large-aperture submillimeter telescope, such as Large Submillimeter Telescope (LST) or Atacama Large Aperture Submillimeter Telescope (AtLAST). The difficulty of MAO is, however, real-time sensing of wavefront deformation with ~10 um accuracy across the aperture. Our wavefront sensor operating at 20 GHz measures the radio path length between a certain position of the primary mirror surface to the focal point where a 20 GHz coherent receiver is placed. With the 2-element prototype, we sampled two positions on the primary mirror surface (at radii of 5 m and 16 m) at a sampling rate of 10 Hz. Then an excess path length (EPL) between the two positions was obtained by differentiating the two optical paths. A power spectral density of the EPL shows three components: a low-frequency drift (1/f^n), oscillations, and a white noise. A comparison of EPL measurements under a variety of wind conditions suggests that the former two are likely induced by the wind load on the telescope structure. The power of the white noise corresponds to a 1sigma statistical error of 8 um in EPL measurements. The 8 um r.m.s. is significant with respect to the mirror surface accuracy required by the LST and AtLAST (~20-40 um r.m.s.), which demonstrates that our technique is also useful for the future large-aperture submillimeter telescopes.Comment: 10 pages, 9 figures. Published in SPIE Pro

Comparison of Vegetation Indices and Spectral Reflectance Observed by Two Types of UAV-mounted Multispectral Camera

departmental bulletin pape

Effects of Cultivation Methods on Paddy Rice Growth Observed by UAV-mounted Multispectral Camera

departmental bulletin pape