• Title/Summary/Keyword: Nagasaki

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Prediction of Specific Noise Based on Internal Flow of Forward Curved Fan

  • Sasaki, Soichi;Hayashi, Hidechito;Hatakeyama, Makoto
    • International Journal of Fluid Machinery and Systems
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    • v.2 no.1
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    • pp.80-91
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    • 2009
  • In this study, a prediction theory for specific noise that is the overall characteristic of the fan has been proposed. This theory is based on total pressure prediction and broadband noise prediction. The specific noises of two forward curved fans with different number of blades were predicted. The flow around the impeller having 120 blades (MF120) was more biased at a certain positions than the impeller with 40 blades (MF40). An effective domain of the energy conversion of MF40 has extended overall than MF120. The total pressure was affected by the slip factor and pressure loss caused by the vortex flow. The suppression of a major pressure drop by the vortex flow and expansion of the effective domain for energy conversion contributed to an increase in the total pressure of MF40 at the design point. The position of maximum relative velocity was different for each fan. The relative velocity of MF120 was less than that of MF40 due to the deviation angle. The specific noise of MF120 was 2.7 dB less than that of MF40 due to the difference in internal flow. It has been quantitatively estimated that the deceleration in the relative velocity contributed to the improvement in the overall performance.

Building a Flood Database and Its Utilization to Reduce Flood Risk (수해시 피해경감을 위한 정보의 정비 및 활용)

  • An, Sang-Hyeok;Noguchi, M.
    • Journal of Korea Water Resources Association
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    • v.33 no.6
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    • pp.681-688
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    • 2000
  • For the reduction of flood damage, it is necessary to analyse shelter activities of local residents and to publish information of floodings, In this paper the control factors of individual refuge activities which are major activities to save peoples lives against floodings have been estimated. Decision making factors for mental refuge activity by the questionnaire survey were classified into two categories: internal and external ones. Furthermore, the behaviour patterns of residents for flood risk related to geographical and social factors were derived by the quantification method n. Since spatial layered information using GIS were corrected and estimated to serve citizen's consensus due to flood disaster, it would aid reduction and minimization of flood risk.d risk.

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Cardiorespiratory Regulations in the Japanese Amberjack (Seriola quinqueradiata) Exposed to Acute Hypoxia (저산소환경이 방어(Seriola quinqueradiata) 순환계의 산소운반 기능에 미치는 영향)

  • LEE Kyoung Seon;ISHIMATSU Atsushi;JEON Joong Kyun
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.38 no.2
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    • pp.106-111
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    • 2005
  • We studied the cardio-respiratory properties in the Japanese amberjack (Seriola quinqueradiata) during acute hypoxia exposure. Fish were exposed to three levels of hypoxia (80, 60 or 50 mmHg) for 60 min at $25^{\circ}C$. Cardiovascular parameters (cardiac output; Q, heart rate; HR, stroke volume; SV, blood pressure; $P_{DA}$) changed little from pre-exposure values during both 80 and 60 mmHg of hypoxia. During 50 mmHg of hypoxia, the fish showed a bradycardia which significantly affected Q, whereas no change in SV. $P_{DA}$ increased transiently. Arterial oxygen partial pressure ($PaO_2$) immediately reduced along with a decrease of the water oxygen partial pressure ($P_WO_2$). Arterial $O_2$ content ($CaO_2$) decreased significantly only after 60 min of 50 mmHg of hypoxia. Arterial pH (pHa) and hematocrit value (Hct) did not change significantly. Comparing the effects of different levels of hypoxia, oxygen delivery to the tissues ($Q\;{\times}\;CaO_2$) should be maintained a constant over a broad range of $P_WO_2$, however, severely depressed below 50 mmHg of hypoxia.

AN ASSESSMENT OF LAND COVER CHANGES AND ASSOCIATED URBANIZATION IMPACTS ON AIR QUALITY IN NAWABSHAH, PAKISTAN: A REMOTE SENSING PERSPECTIVE

  • Shaikh, Asif Ahmed;Gotoh, Keinosuke
    • Proceedings of the KSRS Conference
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    • v.2
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    • pp.555-558
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    • 2006
  • In recent years, urban development has expanded rapidly in Nawabshah City of Pakistan. A major effect associated with this population trend is transformation of the landscape from natural cover types to increasingly impervious urban land. The core objective of this study are to provide time-series information to define and measure the urban land cover changes of Nawabshah, Pakistan between the years 1992 and 2002, and to examine related urbanization impacts on air quality of the study area. Two multi-temporal Landsat images acquired in 1992 and 2002 together with standard topographical maps to measure land cover changes were used in this study. The image processing and data manipulation were conducted using algorithms supplied with the ERDAS Imagine software. An unsupervised classification approach, which uses a minimum spectral distance to assign pixels to clusters, was used with the overall accuracy ranging from 84 percent to 92 percent. Land cover statistics demonstrate that during the study period (1992-2002) extensive transformation of barren and vegetated lands into urban land have taken place in Nawabshah City. Results revealed that land cover changes due to urbanization has not only contaminated the air quality of the study area but also raised the health concerns for the local residents.

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DETECTING THE CAUSES OF WATER LOGGING PROBLEM IN DHAKA CITY BY APPLYING CONTINGENT VALUATION METHOD AND REMOTE SENSING TECHNIQUE

  • Ahmed, Sarwar Uddin;Gotoh, Keinosuke;Hossain, Shahriar
    • Proceedings of the KSRS Conference
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    • v.2
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    • pp.559-562
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    • 2006
  • Although flood is a very common natural disaster in Bangladesh, recently Dhaka, the capital city of Bangladesh got flooded even in moderate rainfall. Accordingly, on January 2002 the sale and use of polythene bags were banned, by identifying it as one of the main causes for such flooding. Now the question arises, whether only polythene shopping bags are alone responsible for causing water logging problem. Accordingly, the objective of this study is to detect the reason(s) for the recent prolonged water logging problem in Dhaka City, even by small amount of rainfall. Both contingent valuation method and remote sensing technique were used for comparison of the results. The results of the study indicated that, not only polythene bags, but also unplanned land filling is also liable for creating water logging problem in Dhaka City. Finally, the study suggested that, the value of wetlands lost, which is directly related to the recent water logging problem, is more higher than what actually thought by the citizens of Dhaka City.

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OCEANOGRAPHIC EVENTS AT NORTHERN BORNEO AND THEIR RELATIONSHIP TO HARMFUL ALGAL BLOOMS

  • Knee, Tan Chun;Ishizaka, Joji;Ransi, Varis;Son, Tong Phuoc Hoang;Tripathy, Sarat Chandra;Siswanto, Eko
    • Proceedings of the KSRS Conference
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    • v.1
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    • pp.491-494
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    • 2006
  • The west coast of Northern Borneo is strongly influenced by Asian monsoon. Present research using the satellite ocean color (OC) remote sensing has identified some interesting oceanographic phenomena in this area that could be related to the harmful algal blooms (HAB). Occurrence of seasonal upwelling event was noticed off the northern tip of Borneo Island that could be related to the northeast monsoon wind. Harmful algal blooms by Pyrodinium bahamense var. compressum occurred since 1976. Subsequently, during December 2003, there was a report of new HAB by Cochlodinium polykrikoides in Northern Borneo. Analysis of OC images revealed that the Cochlodinium bloom had very high chlorophyll a signal and strong absorption characteristics. Results showed that the Baram River plume and upwelling at Northern Borneo were the source of nutrient for the Cochlodinium bloom in the offshore region. Ocean color images of 2004 showed that the bloom from Northern Borneo had crossed the Balabac Straits, reaching Palawan Island in Philippine. Due to the possibility of transboundary HAB problem, we propose a regional HAB monitoring network for an effective HAB management.

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