Latitudinal effect on the growth dynamics of harvested stands of Typha: A modeling approach     

Dinh Ngoc Hai  Takashi Asaeda  Jagath Manatunge 《Estuarine, Coastal and Shelf Science》2006,70(4):613

A model was developed for Typha, to examine the effects of latitudinal changes in temperature and radiation on the partitioning of total biomass during the growing season into rhizomes, roots, flowering and vegetative shoots, and inflorescences.Regardless of initial rhizome biomass, both above and belowground biomasses converge on a equilibrium value, with the balance between total production and metabolic loss being latitude-specific. If aboveground biomass is harvested just once, then both above and belowground biomasses return to equilibrium values after several years. If the aboveground biomass is harvested annually, then both above and belowground biomasses converge on smaller equilibrium values, which are determined by the balance between the sum of production prior to harvesting and after harvesting, and the sum of annual metabolic losses and a loss due to harvesting.The model could be used in wetland management activities to predict the potential growth of Typha in given conditions as well as the responses of Typha stands to harvesting over a wide range of latitudes for times ranging from a season to several years.  相似文献   

A Continuous Mapping of Tidal Current Structures in the Kanmon Strait   总被引：1，自引：0，他引：1  

Keisuke?Yamaguchi  Ju?Lin  Arata?KanekoEmail author  Tokuo?Yayamoto  Noriaki?Gohda  Hong-Quang?Nguyen  Hong?Zheng 《Journal of Oceanography》2005,61(2):283-294

Tidal current structures at the Hayatomono-Seto of the Kanmon Strait are mapped continuously during March 17 to 20, 2003, including a spring tide, by the eight coastal acoustic tomography (CAT) systems distributed on both the sides of the strait. Detailed structures of strong tidal currents and their associated vortices are well reconstructed by the inverse analysis of travel-time difference data obtained from the reciprocal sound transmission between the paired CAT systems located at both sides of the strait mainly. The results are well compared to the shipboard acoustic Doppler current profiler (ADCP) data at the correlation rate of 0.84/0.82 and the RMS difference of 0.47/0.48 ms⁻¹ for the east-west/north-south current after the selection of good data. During the observation period, the maximum hourly mean volume transport for the upper 7 m layer across the strait reached 13,314 m³ s⁻¹ for the eastward and 5,547 m³ s⁻¹ for the westward. The daily mean transport is directed to the eastward and estimated 1,470 m³ s⁻¹ and 2,140 m³ s⁻¹ for March 18 and 19, respectively, when a spring tide occurs.  相似文献   

An application of the E-ε turbulence model for studying coupled air-sea boundary-layer structure     

Le Ngoc Ly 《Boundary-Layer Meteorology》1991,54(4):327-346

An E- turbulence model is used to study air-sea interaction characteristics and turbulence structure using a coupled model for air-sea boundary layers. The E- turbulence model consists of equations for the turbulent kinetic energy, the energy-dissipation, and for the turbulent exchange coefficient expressed in terms of turbulent kinetic energy and energy-dissipation. The energy-dissipation equations for the air-sea interface are solved analytically to obtain boundary conditions for energy-dissipation at the interface. The air-sea interaction and turbulence characteristics of the E- model are compared with those of the mixing-length model and with available observations.The simulations demonstrate that the air-sea interaction parameters obtained by the E- model agree well with observations. The numerical studies also show that the E- turbulence model with appropriate constants can give good results in modeling coupled air-sea boundary-layer flows.  相似文献   

Sedimentation in the floodplains of the Mekong Delta,Vietnam. Part I: suspended sediment dynamics          下载免费PDF全文

Nguyen Nghia Hung  José Miguel Delgado  Andreas Güntner  Bruno Merz  András Bárdossy  Heiko Apel 《水文研究》2014,28(7):3132-3144

Suspended sediment is the primary source for a sustainable agro‐ecosystem in the Mekong Delta by providing nutrient input for the subsequent cropping season. In addition, the suspended sediment concentration (SSC) plays an important role in the erosion and deposition processes in the Delta; that is, it influences the morphologic development and may counteract the deltaic subsidence and sea level rise. Despite this importance, little is known about the dynamics of suspended sediment in the floodplains of the Mekong Delta. In particular, quantitative analyses are lacking mainly because of data scarcity with respect to the inundation processes in the floodplains. In 2008, therefore, a comprehensive in situ system to monitor the dynamics of suspended sediment in a study area located in the Plain of Reeds was established, aiming at the characterization and quantification of suspended sediment dynamics in the deeply inundated parts of the Vietnamese part of the Mekong Delta. The monitoring system was equipped with seven water quality–monitoring stations. They have a robust design and autonomous power supply suitable for operation on inundated floodplains, enabling the collection of reliable data over a long period of time with a high temporal resolution. The data analysis shows that the general seasonal dynamics of suspended sediment transport in the Delta is controlled by two main mechanisms: the flood wave of the Mekong River and the tidal backwater influences from the coast. In the channel network, SSC decreases exponentially with distance from the Mekong River. The anthropogenic influence on SSC could also be identified for two periods: at the start of the floodplain inundation and at the end of the flood period, when subsequent paddy rice crops are prepared. Based on the results, we recommend an operation scheme for the sluice gates, which intends to distribute the sediment and thus the nutrients equally over the floodplain. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Vulnerability in north-central Vietnam: do natural hazards matter for everybody?     

Thorkil Casse  Anders Milhøj  Thao Phuong Nguyen 《Natural Hazards》2015,79(3):2145-2162

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A FEM-MPM hybrid coupled framework based on local shear strength method for simulating rainfall/runoff-induced landslide runout     

Zhu  Yulong  Ishikawa  Tatsuya  Zhang  Yafen  Nguyen  Binh T.  Subramanian  Srikrishnan Siva 《Landslides》2022,19(8):2021-2032

Landslides - Limited by the independence and its defects of each general software package, simultaneous analysis of runoff, seepage, and large-deformation analysis is still an inevitable challenge....  相似文献   

Calculation of seismic bearing capacity of shallow strip foundations using the cell-based smoothed finite element method     

Nguyen  H. C.  Vo-Minh  T. 《Acta Geotechnica》2022,17(8):3567-3590

This paper adopts an upper bound procedure using the cell-based smoothed finite element method (CS-FEM) to estimate the seismic bearing capacity of shallow strip footings, focussing on seismic soil-structure interactions. In simulations, soil behaviour is assumed as the Mohr–Coulomb material, and increment of plasticity deformation obeys the associated flow rule. The first step of the numerical procedure involves approximating the kinematically admissible displacement fields using the cell-based smoothed finite element method, while the second relates to the establishments of the optimization problem as the conic programming. The inclusion of seismic conditions in the simulations was made using the pseudo-static approach. Initially, three seismic bearing capacity factors were resolved for both smooth and rough foundations by including horizontal and vertical inertia forces caused by the soil weight, the superstructure and the surcharge in the analyses. All seismic bearing capacity components obtained are in excellent agreement with those obtained using the method of characteristics and other finite element analyses. Subsequently, the reduction coefficients that correlate static and seismic bearing capacity factors were computed to facilitate the seismic design of the foundation.

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Novel integrated approaches for predicting the compressibility of clay using cascade forward neural networks optimized by swarm- and evolution-based algorithms     

He  Ziguang  Nguyen  Hoang  Vu  Thai Ha  Zhou  Jian  Asteris  Panagiotis G.  Mammou  Anna 《Acta Geotechnica》2022,17(4):1257-1272

Acta Geotechnica - Soft soils are considered as disadvantages in construction, especially in clay layers. It requires many advanced techniques to treat the soft soils before construction, aiming to...  相似文献   

Modelling the Asian summer monsoon using CCAM   总被引：2，自引：1，他引：1  

Kim Chi Nguyen  John L. McGregor 《Climate Dynamics》2009,32(2-3):219-236

A ten-year mean (1989–1998) climatology of the Asian summer monsoon is studied using the CSIRO Conformal-Cubic Atmospheric Model (CCAM) to downscale NCEP reanalyses. The aim of the current study is to validate the model results against previous work on this topic, in order to identify model strengths and weaknesses in simulating the Asian summer monsoon. The model results are compared with available observations and are presented in two parts. In the first part, the mean summer rainfall, maximum and minimum temperatures and winds are compared with the observations. The second part focuses on validation of the monsoon onset. The model captures the mean characteristics such as the cross-equatorial flow of low-level winds over the Indian Ocean and near the Somali coast, rainfall patterns, onset indices, northward movements, active-break and revival periods.  相似文献   

Experimental and numerical behaviour of reinforced mortar plates subjected to accelerated corrosion     

Quang Thanh Nguyen  Sabine Caré  Yves Berthaud  Alain Millard  Frédéric Ragueneau 《国际地质力学数值与分析法杂志》2011,35(10):1141-1159

Most reinforced concrete structures are damaged due to corrosion of reinforcements in concrete. In normal conditions the pH near the reinforcements is around 12–13 which means that steel is in a passive state. But aggressive species, such as chloride ions or carbon dioxide, may penetrate into concrete and promote active corrosion. As a consequence (hydro)oxides are produced leading to degradation of concrete structures. For instance cracking of the concrete is generated due to the pressure induced by rust. In this paper, we study the inception and the propagation of cracking on reinforced mortar plates with rebars located either in the middle or at the corner. Additional experiments have been performed on cylindrical specimens to determine the local effect of rust pressure at the interface rust/mortar. The specimens have been subjected to imposed current density in order to enhance the corrosion and digital image intercorrelation has been used to determine displacement fields. The experiments have been compared to numerical modelling. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献