Modeling the stochastic dependence of air pollution index data   总被引：1，自引：1，他引：0  

Yousif?AlyousifiEmail author  Nurulkamal?Masseran  Kamarulzaman?Ibrahim 《Stochastic Environmental Research and Risk Assessment (SERRA)》2018,32(6):1603-1611

The air pollution index (API) is a common tool, which is often used for determining the quality of air in the environment. In this study, a discrete-time Markov chain model is applied for describing the stochastic behaviour of API data. The study reported in this paper is conducted based on the data collected from Klang city in Malaysia for a period of 3 years (2012–2014). Based on the API data, we considered a five-state Markov chain for depicting the five different states of the air pollution. We identified the Markov chain is an ergodic Markov chain and determined the limiting distribution for each state of the air pollution. In addition, we have identified the mean first passage time from one state to another. Based on the limiting distribution and the mean return time, we found that the risk of occurrences for unhealthy events is small. However, the risk remains notably troubling. Therefore, the standard of air quality in Klang falls within a margin that is considered healthy for human beings.  相似文献   

Dynamic behavior of a smart device on a surface subjected to earthquake motion          下载免费PDF全文

Yunsu Na  Sherif El-Tawil  Ahmed Ibrahim  Ahmed Eltawil 《地震工程与结构动力学》2018,47(9):1905-1920

This paper leverages concepts from an existing model to simulate the planar response of a smart device subjected to friction forces induced by an underlying moving plane. An interpolation technique is used to enhance detection of transition points (between sticking and sliding states), which must be accurately identified because of the frequency of their occurrence during seismic motion. The behavior of a smart device on an unconstrained table or desk, which is itself on a moving floor, is introduced and discussed. After validation of the results using experimental data, the revised model is used to study the sliding potential of smart devices on a surface during strong seismic events. Sliding spectra associated with selected ground motions are presented and extended to incorporate the effect of vertical accelerations with the purpose of assessing their influence. It is shown that vertical accelerations have a minimal effect on the sliding behavior of smart devices and that a “probability of exceeding the slip limit” curve can be developed to relate the probability of sticking to a demand parameter that represents the ground motion.  相似文献   

Efficient ensemble forecasting of marine ecology with clustered 1D models and statistical lateral exchange: application to the Red Sea     

Denis Dreano  Kostas Tsiaras  George Triantafyllou  Ibrahim Hoteit 《Ocean Dynamics》2017,67(7):935-947

Forecasting the state of large marine ecosystems is important for many economic and public health applications. However, advanced three-dimensional (3D) ecosystem models, such as the European Regional Seas Ecosystem Model (ERSEM), are computationally expensive, especially when implemented within an ensemble data assimilation system requiring several parallel integrations. As an alternative to 3D ecological forecasting systems, we propose to implement a set of regional one-dimensional (1D) water-column ecological models that run at a fraction of the computational cost. The 1D model domains are determined using a Gaussian mixture model (GMM)-based clustering method and satellite chlorophyll-a (Chl-a) data. Regionally averaged Chl-a data is assimilated into the 1D models using the singular evolutive interpolated Kalman (SEIK) filter. To laterally exchange information between subregions and improve the forecasting skills, we introduce a new correction step to the assimilation scheme, in which we assimilate a statistical forecast of future Chl-a observations based on information from neighbouring regions. We apply this approach to the Red Sea and show that the assimilative 1D ecological models can forecast surface Chl-a concentration with high accuracy. The statistical assimilation step further improves the forecasting skill by as much as 50%. This general approach of clustering large marine areas and running several interacting 1D ecological models is very flexible. It allows many combinations of clustering, filtering and regression technics to be used and can be applied to build efficient forecasting systems in other large marine ecosystems.  相似文献   

Prediction of Chemical Oxygen Demand (COD) Based on Wavelet Decomposition and Neural Networks     

Davut Hanbay  Ibrahim Turkoglu  Yakup Demir 《洁净——土壤、空气、水》2007,35(3):250-254

The chemical oxygen demand (COD) parameter of a wastewater treatment plant is predicted based on wavelet decomposition, entropy, and neural networks (NN) for rapid COD analysis. This paper also describes the usage of wavelet and NNs for parameter prediction. Data from a wastewater treatment plant in Malatya, Turkey, were used. This dataset consists of daily values of influents and effluents for a year. To reduce the dimension of input parameters and to decrease the NN training time, wavelet decomposition and entropy were used. Test results were presented graphically. The test results of the trained model were found to be closer to the measured COD values.  相似文献   

Petrology of Cr-rich Ophiolitic Chromitites of Bulqiza, Eastern Ophiolitic Belt, Albania     

XIONG Fahui  YANG Jingsui  Paul T. ROBINSON  Yildirim DILEK  MILUSHI Ibrahim  XU Xiangzhen  ZHANG Zhongming  ZHOU Wen  CHEN Yanhong  HUANG Zhu  LAI Shengming  ZHANG Lan 《《地质学报》英文版》2015,89(Z2):102-102

<正>The ultramafic massif of Bulqiza,which belongs to the eastern ophiolitic belt of Albania,is the most important area for metallurgical chromitite ores.The massif consists of a thick(4 km)rock sequence,with a generalized profile from the bottom to the top as follows.The tectonite  相似文献   

An Overview of the Albanian Ophiolite and Related Ore Minerals     

MILUSHI Ibrahim 《《地质学报》英文版》2015,89(Z2):61-64

<正>1 A Short Introduction on the Albanian Ophiolite Albanian ophiolite(or Mirdita ophiolite)represents a remnant of the Tethyan oceanic lithosphere in the territory of Albania,as an elongated belt from south to the north,about 250 km long and 30-50 km wide.It covers an area of about 4300 km2 or 1/7 of the territory of Albania and is  相似文献   

Site response assessment of an urban extension site using microtremor measurements,Ahud Rufeidah,Abha District,Southwest Saudi Arabia     

Almadani  Sattam  Abdelrahman  Kamal  Ibrahim  Elkhedr  Al-Bassam  Abdulaziz  Al-Shmrani  Awad 《Arabian Journal of Geosciences》2015,8(4):2347-2357

Arabian Journal of Geosciences - Microtremor horizontal-to-vertical spectral ratio (HVSR) method has been conducted at 33 sites in Ahud Rufeidah urban expansion zone in order to assess the...  相似文献   

Simultaneous perturbation stochastic approximation for tidal models     

Muhammad Umer Altaf  Arnold W. Heemink  Martin Verlaan  Ibrahim Hoteit 《Ocean Dynamics》2011,61(8):1093-1105

The Dutch continental shelf model (DCSM) is a shallow sea model of entire continental shelf which is used operationally in the Netherlands to forecast the storm surges in the North Sea. The forecasts are necessary to support the decision of the timely closure of the moveable storm surge barriers to protect the land. In this study, an automated model calibration method, simultaneous perturbation stochastic approximation (SPSA) is implemented for tidal calibration of the DCSM. The method uses objective function evaluations to obtain the gradient approximations. The gradient approximation for the central difference method uses only two objective function evaluation independent of the number of parameters being optimized. The calibration parameter in this study is the model bathymetry. A number of calibration experiments is performed. The effectiveness of the algorithm is evaluated in terms of the accuracy of the final results as well as the computational costs required to produce these results. In doing so, comparison is made with a traditional steepest descent method and also with a newly developed proper orthogonal decomposition-based calibration method. The main findings are: (1) The SPSA method gives comparable results to steepest descent method with little computational cost. (2) The SPSA method with little computational cost can be used to estimate large number of parameters.  相似文献   

The Nile countries,Egypt and the Sudan —social and environmental problems of development     

Fouad N. Ibrahim 《GeoJournal》1982,4(1):2-4

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Rainfall‐runoff modelling using artificial neural networks technique: a Blue Nile catchment case study     

Mamdouh A. Antar  Ibrahim Elassiouti  Mohamed N. Allam 《水文研究》2006,20(5):1201-1216

A rainfall‐runoff model based on an artificial neural network (ANN) is presented for the Blue Nile catchment. The best geometry of the ANN rainfall‐runoff model in terms of number of hidden layers and nodes is identified through a sensitivity analysis. The Blue Nile catchment (about 300 000 km²) in the Nile basin is selected here as a case study. The catchment is classified into seven subcatchments, and the mean areal precipitation over those subcatchments is computed as a main input to the ANN model. The available daily data (1992–99) are divided into two sets for model calibration (1992–96) and for validation (1997–99). The results of the ANN model are compared with one of physical distributed rainfall‐runoff models that apply hydraulic and hydrologic fundamental equations in a grid base. The results over the case study area and the comparative analysis with the physically based distributed model show that the ANN technique has great potential in simulating the rainfall‐runoff process adequately. Because the available record used in the calibration of the ANN model is too short, the ANN model is biased compared with the distributed model, especially for high flows. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献