http://tainguyenso.vnu.edu.vn/jspui/handle/123456789/7490 2026-05-17T13:12:38Z 2026-05-17T13:12:38Z Tran, Ngoc Anh Nguyen, Duc Hanh Luong, Phuong Hau Shinichiro, Onda http://tainguyenso.vnu.edu.vn/jspui/handle/123456789/7673 2011-05-19T03:04:09Z 2010-01-01T00:00:00Z

The Applicability of 3D Hydrodynamic Model on Flow around Hydraulic Structure in Vietnam Tran, Ngoc Anh; Nguyen, Duc Hanh; Luong, Phuong Hau; Shinichiro, Onda Hydraulic structures such as spur dyke or embankment are popular in river training engineering. The flow around hydraulic structures definitely has complicated three-dimensional nature and has been the subject of studies using numerical models. The current 3D model has been applying on many experiments in laboratory but the applicability to the real river is still in question. This paper shows some results of 3D simulation of flow around structure in a natural river. The original 3D model for bed sediment load was improved by including the suspended sediment in order to adapt with rivers in Vietnam then it was applied to a segment of Red river nearby Hanoi city.

2010-01-01T00:00:00Z Nguyen, Tien Giang Daniel, Van Putten http://tainguyenso.vnu.edu.vn/jspui/handle/123456789/7671 2011-05-19T03:00:12Z 2010-01-01T00:00:00Z

Uncertainty Interval Estimation of WetSpa Model for Flood Simulation: a Case Study of Ve Watershed, Quang Ngai Province,Vietnam Nguyen, Tien Giang; Daniel, Van Putten This paper presents the results of a research on uncertainty interval estimation of WetSpa model for flood simulation in Ve watershed. The method applied to uncertainty estimation is the GLUE methodology. The initial results show that uncertainty intervals obtained are reasonably capture the observations with the use of Nash-Sutcliff as likelihood measure. Over-estimation often occur with the low flow, which is acceptable in case of flood simulation. To estimate the prediction interval, the model should be run in prediction mode.

2010-01-01T00:00:00Z Nguyen, Thi Ngoc Katsuaki, Koike http://tainguyenso.vnu.edu.vn/jspui/handle/123456789/7667 2011-05-19T02:44:27Z 2010-01-01T00:00:00Z

Geostatistical Characterization of Grain Size Distribution of Intertidal Sediments in Ba Lat Estuary, Vietnam Nguyen, Thi Ngoc; Katsuaki, Koike Intertidal estuarine sediment grain size is one of the environmental parameters that can explain the interaction between the marine and terrestrial environments. Geostatistics has been widely used to model spatial distribution of many geological objects. However, there has been a few researches concerning with application to grain size distribution. The aim of this study is to clarify surface sediment distribution of tidal flats based on the geostatistical approach. A total of 116 surface sediment samples were collected from the tidal flats in Ba Lat estuary. Grain size of these samples was determined by means of sieve and pipette. Data of sand content (percent of fraction > 0.063 mm) in the sediments were characterized by ordinary kriging (OK) to model sediment distribution. In the study area, four sediment types could be recognized: sand, muddy sand, sandy mud and mud. The sandy sediment types are dominant from the near sea shoals (Con Mo, Con Vanh, Con Thu) to centre of study area. The muddy sediment types concentrate on from inner edge to centre of study area, where mangroves cover partly these tidal flats. These results can contribute to explain the hydro-dynamic and environmental pollution processes in the estuarine area.

2010-01-01T00:00:00Z Nguyen, Tran Huong Giang Nguyen, Thi Kim Oanh http://tainguyenso.vnu.edu.vn/jspui/handle/123456789/7664 2011-05-19T02:39:54Z 2010-01-01T00:00:00Z

Roadside PM 2.5 and BTEX Air Quality in Ho Chi Minh City and Inverse Modeling for Vehicle Emission Factor Nguyen, Tran Huong Giang; Nguyen, Thi Kim Oanh The roadside PM2.5 and BTEX pollutions were monitored in relation to traffic volume at a typical urban street in Ho Chi Minh City (HCMC), Vietnam. The 24-h PM2.5 concentration was 53 – 129 µg/m3 while 8-h PM2.5 concentration was 50 – 170 µg/m3. The hourly levels of benzene, toluene, ethylbenzene, m,p-xylenes and o-xylene vary between 6 – 53, 14 – 170, 3 – 24, 5 – 59, and 2 - 21 µg/m3, respectively, within a day. During the daytime higher concentrations were observed on weekdays than weekend but the opposite was observed at the nighttime and early morning when weekend had higher concentrations. This corresponds to the variations in traffic volume between weekdays and weekend. Pollution levels measured within 30 m from the traffic lane were found to reduce with increasing downwind distance. Principal component analysis (PCA) was applied to the set of air pollution concentration and traffic volume data which revealed that diesel fueled vehicles (truck and bus) were associated with PM2.5 while gasoline fueled vehicles (motorcycle, car, and delivery tricycle) were linked to BTEX. Vans were associated with both PM2.5 and BTEX as they use both diesel and gasoline fuels.Inverse CALINE4 modeling produced the average emission factors of PM2.5, benzene, toluene, ethylbenzene, m,p-xylenes, and o-xylene for the whole street fleet of 38 ± 3.9; 23 ± 4.3; 74 ± 14.8; 8 ± 1.3; 28 ± 9.5; and 9 ± 2.5 mg/vehicle.km which correspond to hourly fleet emission ranges during a day of 141 – 388; 18 – 435; 52 – 1493; 6 – 131; 18 – 655; and 6 - 194 g/km.hour, respectively. Solving the multilinear equation system constructed based on the hourly fleet emission and fleet composition was revealed that the gasoline fueled vehicles had lower PM2.5 emission factor but higher benzene, toluene, ethylbenzene, m,p-xylenes, and o-xylene emission factors than the diesel fueled vehicles. The corresponding emission factors for gasoline fueled vehicles were 25 ± 2.4; 22 ± 0.1; 68 ± 0.3; 8 ± 0.1; 22 ± 0.1; and 8 ± 0.1 mg/vehicle.km, respectively, while for diesel fueled vehicles the emission factors were 388 ± 164.0; 17 ± 5.3; 61 ± 22.2; 4 ± 3.3; 20 ± 5.5; and 5 ± 2.9 mg/vehicle.km, respectively.

2010-01-01T00:00:00Z