Support vector regression methodology for prediction of output energy in rice production     

Marziye Yousefi  Benyamin Khoshnevisan  Shahaboddin Shamshirband  Shervin Motamedi  Mohd Hairul Nizam Md. Nasir  Muhammad Arif  Rodina Ahmad 《Stochastic Environmental Research and Risk Assessment (SERRA)》2015,29(8):2115-2126

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Anisotropy in volume change behaviour of soils during shrinkage     

Mishra  Partha Narayan  Zhang  Yuan  Bhuyan  Md Habibullah  Scheuermann  Alexander 《Acta Geotechnica》2020,15(12):3399-3414

It has been long recognised that some of the fundamental and engineering properties of soils exhibit a certain degree of anisotropy that eventually dictates their directional geoengineering behaviours. Consideration of the importance of the volume change behaviour of soils during shrinkage and a critical review of the literature suggests scopes for further research for the development of a better understanding of the anisotropy in volume change encountered during soil shrinkage. In this paper, anisotropy in volumetric shrinkage behaviour of soil is depicted with the theory of geometry factor and shrinkage strains. A systematic investigation and analysis on the evolution of geometry factors and shrinkage strains of several geomaterial samples during evaporative dewatering is reported herein. A theoretical framework for evaluating shrinkage geometry factors of a cylindrical soil specimen undergoing volume change during progressive moisture loss is described in this paper. Furthermore, based on experimental and literature data, shrinkage geometry factors of several specimens differing in terms of gradational properties, specimen size, evaporative boundary condition and pore fluid salinity are evaluated and discussed in detail in accordance with the theoretical framework. Linkages between shrinkage process, shrinkages strains and geometry factor are also analysed to underpin the usage of geometry factor and shrinkage strains to characterise anisotropy during soil shrinkage.

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Seasonal Shift in Community Structure of Periphytic Ciliates in Estuarine Waters in the Northern Bay of Bengal,Bangladesh     

Mamun?Abdullah Al  Rahman?Muhammed?Forruq  Aysha?Akhtar  Md.?Wahidul?Alam  Mohammad?Nurul?Azim?Sikder  Alan?Warren  Henglong?XuEmail author 《Ocean Science Journal》2018,53(4):707-718

To investigate the seasonal heterogeneity of the periphytic ciliate communities, a 1-year baseline survey was conducted in the Karnaphuli River estuary, northern Bay of Bengal, Bangladesh. A total of 54 ciliate species were recorded, including seven common and 14 dominant species. Maximum species number was in autumn whereas maximum abundance was in winter; the minimum for both occurred in summer. Multivariate analyses, i.e., canonical analysis of principal coordinates (CAP) and principal co-ordinates analysis (PCoA), revealed a clear seasonal heterogeneity of community structure and environmental variables. Multivariate correlation analysis (RELATE) demonstrated that the community structure of the periphytic ciliate communities was significantly correlated with environmental variables, and best matching analysis (BIOENV) indicated that heterogeneity of community patterns was mainly driven by water temperature, pH, dissolved oxygen, total dissolved solids and nutrients. Species richness and diversity peaked in autumn whereas species evenness peaked in summer. These results suggest that environmental conditions shape periphytic ciliate community structure, which is a potentially useful bio-indicator of estuarine water quality.  相似文献   

Assessment of Red Bed Groundwater in the Jinqu Basin,Southeastern China: Its Enrichment Regularity and Emergency Exploitation Potential     

Zhao  Yu  Zhang  Yongfa  Yang  Haiqing  Tian  Xin  Emdadul  Haque Md.  Mouhamadou  Faouziatou 《Natural Resources Research》2020,29(6):3743-3769

Natural Resources Research - Due to unbalanced spatial distribution and insufficient capacity allocation of water resources in the Jinqu Basin, developing and utilizing the red bed groundwater...  相似文献   

Numerical storm surge model with higher order finite difference method of lines for the coast of Bangladesh   总被引：1，自引：0，他引：1  

Paul Gour Chandr  Ali Md. Emran 《海洋学报(英文版)》2019,38(6):100-116

In this study, the method of lines (MOLs) with higher order central difference approximation method coupled with the classical fourth order Runge-Kutta (RK(4,4)) method is used in solving shallow water equations (SWEs) in Cartesian coordinates to foresee water levels associated with a storm accurately along the coast of Bangladesh. In doing so, the partial derivatives of the SWEs with respect to the space variables were discretized with 5-point central difference, as a test case, to obtain a system of ordinary differential equations with time as an independent variable for every spatial grid point, which with initial conditions were solved by the RK(4,4) method. The complex land-sea interface and bottom topographic details were incorporated closely using nested schemes. The coastal and island boundaries were rectangularized through proper stair step representation, and the storing positions of the scalar and momentum variables were specified according to the rules of structured C-grid. A stable tidal regime was made over the model domain considering the effect of the major tidal constituent, M₂ along the southern open boundary of the outermost parent scheme. The Meghna River fresh water discharge was taken into account for the inner most child scheme. To take into account the dynamic interaction of tide and surge, the generated tidal regime was introduced as the initial state of the sea, and the surge was then made to come over it through computer simulation. Numerical experiments were performed with the cyclone April 1991 to simulate water levels due to tide, surge, and their interaction at different stations along the coast of Bangladesh. Our computed results were found to compare reasonable well with the limited observed data obtained from Bangladesh Inland Water Transport Authority (BIWTA) and were found to be better in comparison with the results obtained through the regular finite difference method and the 3-point central difference MOLs coupled with the RK(4,4) method with regard to the root mean square error values.  相似文献   

Origin of the regional stress field along the Liquine-Ofqui Fault Zone （LOFZ）, Southern Chilean Andes by means of FE Simulation     

Md.Rafiqul Islam 《山地科学学报》2009,6(1):1-13

The Liquine-Ofqui Fault Zone （LOFZ） of southern Chilean Andes is one of the largest active strike-slip fault zones. There is an ongoing debate regarding the origin of the stress field along the LOFZ due to its complex geometry. This paper represents a study of the origins of the LOFZ regional stress field. Stress fields are calculated by finite element （FE） analysis. The two possible stress origins, i.e., oblique plate convergence and ridge collision/indenter tectonics of Chile ridge against Peru-Chile trench, have been emphasized in the present study. Three types of boundary conditions for the three particular models have been applied to calculate stress fields. Models are assumed to be elastic and plane stress condition. Modeling results are presented in terms of four parameters, i. e., orientation of maximum horizontal stress （σHmax）, displacement vector, strain distribution, and maximum shear stress （ τmax ） contour line within the model. The results of the first model with oblique plate convergence show inconsistency between the geometric shape of the LOFZ and the distribution of the four parameters. Although more realistic results are obtained from the second model with normal ridge collision, there are few coincident in the LOFZ geometry and regional stress field. The third model with normal and oblique ridge collision is reasonable in understanding the origin of stress field and geometrical condition in the lithosphere of the LOFZ.  相似文献   

利用Landsat TM和IRS P6 LISS III卫星影像及GIS对耕地和耕种模式的时空动态分析(英文)   总被引：2，自引：0，他引：2  

Md.Rejaur Rahman  S.K.Saha 《地球空间信息科学学报》2009,12(2):123-134

The study of the spatial patterns and temporal changes of cropland is important to understand the underlying factors and the functional effects of the agricultural landscape. On the other hand, crop dynamics mapping is essential to know the overall agro-spatial diversity of the area. Therefore, this paper addressed a spatio-temporal analysis of cropland and cropping pattern change in the Bogra district of Bangladesh over the last 16 years (between 1988/89 and 2004/05). In this paper, crop mapping from multi-temporal and multi-sensor satellite images was described. Landsat TM and IRS P6 LISS III satellite images were used with GIS for spatial dynamics of cropland and cropping pattern change analysis. First, seasonal cropland maps were derived from object-based classification of satellite images, then two-date classified image differencing with GIS overlay technique and decision rules were applied. Cropping pattern change was analyzed in a spatial and quantitative way for the 16 years and for this, Integrated Land and Water Information System (ILWIS) and Land Change Modular (LCM) of IDRISI Andes were used. The results showed that in the area, mono crop cultivation was found in summer, but in winter, areas under different crop cultivation had changed dramatically. Change analysis showed that the changes mainly occurred in the north northwest and southwest of the areas, and during the time the highest change area was found under the rice-potato pattern.   相似文献   

Hydrological dynamics of prairie pothole wetlands: Dominant processes and landscape controls under contrasted conditions          下载免费PDF全文

Aminul Haque  Genevieve Ali  Pascal Badiou 《水文研究》2018,32(15):2405-2422

Numerous studies have examined the impact of prairie pothole wetlands on overall watershed dynamics. However, very few have looked at individual wetland dynamics across a continuum of alteration status using subdaily hydrometric data. Here, the importance of surface and subsurface water storage dynamics in the prairie pothole region was documented by (1) characterizing surface fill–spill dynamics in intact and consolidated wetlands; (2) quantifying water‐table fluctuations and the occurrence of overland flow downslope of fully drained wetlands; (3) assessing the relation (or lack thereof) between intact, consolidated or drained wetland hydrological behaviour, and stream dynamics; and (4) relating wetland hydrological behaviour to landscape characteristics. Focus was on southwestern Manitoba, Canada, where ten intact, three consolidated, seven fully drained wetlands, and a nearby creek were monitored over two years with differing antecedent storage conditions. Hourly hydrological time series were used to compute behavioural metrics reflective of year‐specific and season‐specific wetland dynamics. Behavioural metrics were then correlated to wetland physical characteristics to identify landscape controls on wetland hydrology. Predictably, more frequent spillage or overland flow was observed when antecedent storage was high. Consolidated wetlands had a high degree of water permanence and a greater frequency of fill–spill events than intact wetlands. Shallow and highly responsive water tables were present downslope of fully drained wetlands. Potential wetland–stream connectivity was also inferred via time‐series analysis, while some landscape characteristics (e.g., wetland surface, catchment area, and storage volume) strongly correlated with wetland behavioural metrics. The nonstationarity of dominant processes was, however, evident through the lack of consistent correlations across seasons. This, therefore, highlights the importance of combining multiyear high‐frequency hydrometric data and detailed landscape analyses in wetland hydrology studies.  相似文献   

Correction to: Nexus between vulnerability and adaptive capacity of drought-prone rural households in northern Bangladesh     

Salam  Roquia  Islam  Abu Reza Md. Towfiqul  Shill  Badhon Kumar  Alam  G. M. Monirul  Hasanuzzaman  Md.  Hasan  Md. Morshadul  Ibrahim  Sobhy M.  Shouse  Roger C. 《Natural Hazards》2021,106(1):529-529

Natural Hazards - The article was published with a spelling error in one of the co-author names. The correct spelling is reflected in this correction, and the original work has been updated to...  相似文献   

The Spatial Structure of Zooplankton Communities of Pedu Reservoir, Malaysia     

Johan Ismail  Diana Latief 《湿地科学》2012,10(4):423-428

A total of 22 species of zooplankton were identified from 8 sampling stations located in the limnetic zone of Pedu reservoir.The zooplankton community was dominated by rotifers (11 species),followed by cladocerans (9 species) and copepods (2 species).Four species of zooplankton comprised of 3 rotifers,Brachionus quadridentata,Brachionus caudatus and Keratella cochlearis and one cladoceran,Ceriodaphnia cornuta were present at all sampling stations.Species richness was highest at Station 2 (17 species) followed by Station 4 and Station 8 (14 species),Station 5 (15 species),Station 7 (11 species),Station 6 (10 species),Station 3 (9 species) and Station 1 (7 species).With an exception of water transparency,all other water quality parameters such as temperature,dissolved oxygen,conductivity,pH and total dissolved solids were not significant when compared between sampling stations.The study found that station 5 which was located in a calm strait,protected from strong wave and wind was a suitable area for zooplankton growth and establishment.Factors supporting the findings included highest water transparency (3.4 m),rich in species numbers (15 species),high diversity index (0.950) and evenness index (0.808).  相似文献