飓风Juan(2003)路径附近实测飓风浪的谱特性研究   总被引：2，自引：1，他引：1  

XU Fumin  BUI THI Thuy Duyen  PERRIE Will 《海洋学报(英文版)》2014,33(11):112-122

Hurricane Juan provides an excellent opportunity to probe into the detailed wave spectral patterns and spectral parameters of a hurricane system, with enough wave spectral observations around Juan＇s track in the deep ocean and shallow coastal water. In this study, Hurricane Juan and wave observation stations around Juan＇s track are introduced. Variations of wave composition are discussed and analyzed based on time series of one-dimensional frequency spectra, as well as wave steepness around Juan＇s track： before, during, and after Juan＇s passing. Wave spectral involvement is studied based on the observed one-dimensional spectra and two-dimensional spectra during the hurricane. The standardization method of the observed wave spectra during Hurricane Juan is discussed, and the standardized spectra show relatively conservative behavior, in spite of the huge variation in wave spectral energy, spectral peak, and peak frequency during this hurricane. Spectral widths＇ variation during Hurricane Juan are calculated and analyzed. A two-layer nesting WW3 model simulation is applied to simulate the one-dimensional and two-dimensional wave spectra, in order to examine WW3＇s ability in simulating detailed wave structure during Hurricane Juan.  相似文献   

Floor spectra of mixed base isolated structures     

Ioannis Politopoulos  Hoan Khac Pham 《Bulletin of Earthquake Engineering》2011,9(4):1115-1135

This work investigates the efficiency of mixed base isolation, combining passive isolation bearings with semi-active (SAC) devices, to reduce the floor spectral acceleration in the vicinity of the non-isolated modes’ frequencies. Both analytical and experimental studies have been carried out. Analytical results of the behaviour of a multiple degree of freedom base isolated structure demonstrate the efficacy of the method. Though the considered controller is based on a reduced order model with only two degrees of freedom (2 DOF) without spillover compensation, the results show that, for the type of structures studied here, spillover effects are not considerable. An experimental study of a 2 DOF model of a base isolated structure equipped with a semi-active magneto-rheological (MR) damper has been carried out. Due to limitations of the experimental set-up, it has not been possible to obtain direct experimental evidence of the efficacy of SAC control to improve floor spectra. Nevertheless, based on the good agreement between analytical and experimental results which validate the considered MR model and control algorithm, numerical analyses of more relevant configurations illustrated the benefit of the utilization of such devices.  相似文献   

Modeling regional sediment transport and shoreline response in the vicinity of tidal inlets on the Long Island coast,United States     

Le Xuan Hoan  Hans Hanson  Magnus Larson  Pham Thanh Nam 《Coastal Engineering》2011

A new numerical model was developed to simulate regional sediment transport and shoreline response in the vicinity of tidal inlets based on the one-line theory combined with the reservoir analogy approach for volumetric evolution of inlet shoals. Sand bypassing onshore and sheltering effects on wave action from the inlet bar and shoals were taken into account. The model was applied to unique field data from the south coast of Long Island, United States, including inlet opening and closure. The simulation area extended from Montauk Point to Fire Island Inlet, including Shinnecock and Moriches Inlets. A 20-year long time series of hindcast wave data at three stations along the coast were used as input data to the model. The capacity of the inlet shoals and bars to store sand was estimated based on measured cross-sectional areas of the inlets as well as on comprehensive bathymetric surveys of the areas around the inlet. Several types of sediment sources and sinks were represented, including beach fills, groin systems, jetty blocking, inlet bypassing, and flood shoal and ebb shoal feeding. The model simulations were validated against annual net longshore transport rates reported in the literature, measured shorelines, and recorded sediment volumes in the flood and ebb shoal complexes. Overall, the model simulations were in good agreement with the measured data.  相似文献   

水电项目对越南硒圣河地区社会经济发展及环境保护的影响     

乐庭青  武四兰 《资源与生态学报(英文版)》2011,(4):375-379

硒圣河是湄公河的主要分支之一,其集水区地形条件和水资源量均对水电开发十分有利。此外,无论从物种多样性还是生物量来看,硒圣河水生生物资源非常丰富。鱼类是当地人们的重要食物来源,粗略估计鱼类物种数量可能在200-300种之间,目前具有详细记录的鱼类大约为120种。截至目前,从越南境内硒圣河上游至越-柬边界总共开发了6个水电项目,兴建了一座4A级硒圣调蓄水库。流经柬埔寨的硒圣河部分,依据发展规划将兴建3座水电站,即硒圣5号电站（硒圣1号电站以下）、硒圣3号电站、硒圣2号电站。硒圣河水电项目对区域（越南和柬埔寨）社会经济的影响体现在：为地处偏远和困难的集水区创造了新的能源资源,改善了交通系统和农村地区的生活条件。与此同时,这些水电项目也对该区域自然环境产生了重大影响。例如,改变了下游流动机理变化,导致下游河道淤积,对沿河生态系统也产生了一定影响。  相似文献   

Fuzzy finite element analysis of a foundation on an elastic soil medium     

S. Valliappan  T. D. Pham 《国际地质力学数值与分析法杂志》1993,17(11):771-789

One of the important factors that lead to errors in settlement predicitions is the degree of precision in obtaining the soil parameters. Most mathematical methods for reliability modelling offered to date in the area of geomechanics are based on the classical probabilistic approach, in which soil properties are treated as random variables. In this paper, a model based on the theory of fuzzy sets is presented to take account of the uncertainty in the soil behaviour. This proposed method considers the elastic modulus and Poisson's ratio as two fuzzy numbers in the elastic matrix. An example is given to show the possibility distributions of the displacements and the stresses at some locations in the soil medium. By means of a fuzzy inference scheme, the total possibility distributions or total membership functions of the finite element results may be obtained by considering the estimated error resulting from the mesh discretization.  相似文献   

SOME PRELIMINARY RESULTS FROM STUDY OF CRUSTAL DEFORMATION IN VIETNAM     

Cao Dinh Trieu  Le Van Dung  Nguyen Huu Tuyen  Pham Nam Hung 《大地测量与地球动力学》2003,23(Z1)

1　IntroductionOneofthemaintasksinstudyinggeodynamicprocessisevaluatingtherateofearthcrustmove ments.Normally ,themethodsforstudyingearthcrustmovementareestablishedonthebasisoftheobjectofstudyandtherequirementsfortheresultstobeobtainedasfollows.1 )Tostudythemovingprocessofcrustplatesinalargeareaandwithinacertaintectonicperiod ,geologicmethodsareusuallyused .2 )Geodeticmeasurementsarecarriedoutinanareacoveringfromsomekm2 totensofkm2 andal lowtodeterminethedisplacementoftheearthcrustwithinaperio…  相似文献   

Predicting water flow in fully and partially saturated porous media: a new fractal-based permeability model     

A.  Nguyen Van Nghia  Jougnot  Damien  Thanh  Luong Duy  Van Do  Phan  Thuy  Tran Thi Chung  Hue  Dang Thi Minh  Hung  Nguyen Manh 《Hydrogeology Journal》2021,29(6):2017-2031

Hydrogeology Journal - Predicting the permeability of porous media in saturated and partially saturated conditions is of crucial importance in many geo-engineering areas, from water resources to...  相似文献   

Improved flood susceptibility mapping using a best first decision tree integrated with ensemble learning techniques     

Binh Thai Pham  Abolfazl Jaafari  Tran Van Phong  Hoang Phan Hai Yen  Tran Thi Tuyen  Vu Van Luong  Huu Duy Nguyen  Hiep Van Le  Loke Kok Foong 《地学前缘(英文版)》2021,12(3):101105

Improving the accuracy of flood prediction and mapping is crucial for reducing damage resulting from flood events. In this study, we proposed and validated three ensemble models based on the Best First Decision Tree (BFT) and the Bagging (Bagging-BFT), Decorate (Bagging-BFT), and Random Subspace (RSS-BFT) ensemble learning techniques for an improved prediction of flood susceptibility in a spatially-explicit manner. A total number of 126 historical flood events from the Nghe An Province (Vietnam) were connected to a set of 10 flood influencing factors (slope, elevation, aspect, curvature, river density, distance from rivers, flow direction, geology, soil, and land use) for generating the training and validation datasets. The models were validated via several performance metrics that demonstrated the capability of all three ensemble models in elucidating the underlying pattern of flood occurrences within the research area and predicting the probability of future flood events. Based on the Area Under the receiver operating characteristic Curve (AUC), the ensemble Decorate-BFT model that achieved an AUC value of 0.989 was identified as the superior model over the RSS-BFT (AUC = 0.982) and Bagging-BFT (AUC = 0.967) models. A comparison between the performance of the models and the models previously reported in the literature confirmed that our ensemble models provided a reliable estimate of flood susceptibilities and their resulting susceptibility maps are trustful for flood early warning systems as well as development of mitigation plans.  相似文献   

Investigating the impacts of typhoon-induced floods on the agriculture in the central region of Vietnam by using hydrological models and satellite data     

Nga Thi Thanh Pham  Quang Hong Nguyen  Anh Duc Ngo  Hang Thi Thu Le  Cong Tien Nguyen 《Natural Hazards》2018,92(1):189-204

Flooding associated with landing tropical cyclones (TCs) is one of the major natural hazards in the coastal region of Vietnam. Annually, approximately 5 or 6 TCs make landfall in Vietnam, bringing heavy rains and inducing flooding, particularly to the central coastal region because of its topography and geographic configuration. This study focuses on the modelling of typhoon-induced floods that have resulted in widespread damage to agriculture over the central Thua Thien Hue Province of Vietnam by coupling two well-known hydrological models, KINEROS2 and HEC-RAS (Daniel et al. in Open Hydrol J 5(1), 2011), and using GSMaP (Global Satellite Mapping of Precipitation) data as the satellite rainfall input. Landsat imagery and GIS are also used for mapping and analysing the inundated areas. The discharge and water level from the KINEROS2 and HEC-RAS models displayed acceptable results for the floods modelled from three selected typhoons; both the Nash–Sutcliffe simulation efficiency coefficient (NSE) and the coefficient of determination (R²) were greater than 0.6. The simulated inundation maps of these typhoon-induced floods were compared with those extracted from the Landsat imagery to assess consistency. The result revealed a similar spatial extension of the inundated agricultural areas. This information, together with the forecasted TC movements and associated rainfalls, will be helpful to plan methods for mitigating potential typhoon-induced flooding and damage, particularly damage to agricultural regions.  相似文献   

Correcting the distortion of apparent resistivity pseudosection produced by 3D effect of the embankment geometry     

Trung Nhu Nguyen  Kien Ngoc Pham 《Environmental Earth Sciences》2018,77(3):105

Two-dimensional electrical resistivity tomography data acquired on the crest of the embankment are distorted by the 3D effect of the embankment geometry, reservoir water level and abutment. The distortion affects seriously the final solution of the 2D inverse problem. By comparing the apparent resistivity pseudosections from a 3D and 2D electrical resistivity model of the embankment, the distortion degrees of the apparent resistivity pseudosections along the axis on the crest were estimated for the cases of reservoir and which does not contain water. The obtained results indicate that the distortion degree acquired in the case of a reservoir that contains water was much less than that in the case of the reservoir that does not contain water. In the case of reservoir that contains water, the apparent resistivity pseudosections of the P–P and ED–ED arrays had the largest distortion degree and of D–D, W–S and P–D arrays had the smallest distortion degree. In the case of the reservoir that does not contain water, the apparent resistivity pseudosection of P–P array had the smallest distortion among all arrays. Through modeling investigation, a correction process to reduce the distortion of the apparent resistivity pseudosection was proposed. The correction process was tested in the embankment model, and two field works were carried out in the To Lich River in Hanoi and Khuan Cat embankment in Lang Son province, Vietnam. It is possible to bring the distortion of the apparent resistivity pseudosection down to 2.8–13.9%, depending on the type of electrode arrays and the type of reservoirs, containing or does not contain water. The distortion correction of the apparent resistivity pseudosection is strongly recommended before doing the 2D inverse interpretation.  相似文献