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11.
Ayman F. Habib Ana Paula Kersting Ki-In Bang Ruifang Zhai Mohannad Al-Durgham 《The Photogrammetric Record》2009,24(126):171-195
Lidar (laser scanning) technology has been proven as a prominent technique for the acquisition of high-density and accurate topographic information. Because of systematic errors in the lidar measurements (drifts in the position and orientation information and biases in the mirror angles and ranges) and/or in the parameters relating the system components (mounting parameters), adjacent lidar strips may exhibit discrepancies. Although position and orientation drifts can have a more significant impact, these errors and their impact do not come as a surprise if the quality of the GPS/INS integration process is carefully examined. Therefore, the mounting errors are singled out in this work. The ideal solution for improving the compatibility of neighbouring strips in the presence of errors in the mounting parameters is the implementation of a rigorous calibration procedure. However, such a calibration requires the original observations, which may not be usually available. In this paper, a strip adjustment procedure to improve the compatibility between parallel lidar strips with moderate flight dynamics (for example, acquired by a fixed-wing aircraft) over an area with moderately varying elevation is proposed. The proposed method is similar to the photogrammetric block adjustment of independent models. Instead of point features, planar patches and linear features, which are represented by sets of non-conjugate points, are used for the strip adjustment. The feasibility and the performance of the proposed procedure together with its impact on subsequent activities are illustrated using experimental results from real data. 相似文献
12.
利用NOAA-AVHRR数据分析1982-2001年间中国植被的动态变化(英文) 总被引:1,自引:0,他引:1
The authors derived the normalized difference vegetation index (NDVI) from the NOAA/AVHRR Land dataset, at a spatial resolution of 8km and 15-day intervals, to investigate the vegetation variations in China during the period from 1982 to 2001. Then, GIS is used to examine the relationship between precipitation and the Normalized Difference Vegetation Index (NDVI) in China, and the value of NDVI is taken as a tool for drought monitoring. The results showed that in the study period, China’s vegetation cover h... 相似文献
13.
This article presents a method for the nonlinear analysis of laterally loaded rigid piles in cohesive soil. The method considers the force and the moment equilibrium to derive the system equations for a rigid pile under a lateral eccentric load. The system equations are then solved using an iteration scheme to obtain the response of the pile. The method considers the nonlinear variation of the ultimate lateral soil resistance with depth and uses a new closed‐form expression proposed in this article to determine the lateral bearing factor. The method also considers the horizontal shear resistance at the pile base, and a bilinear relationship between the shear resistance and the displacement is used. For simplicity, the modulus of horizontal subgrade reaction is assumed to be constant with depth, which is applicable to piles in overconsolidated clay. The nonlinearity of the modulus of horizontal subgrade reaction with pile displacement at ground surface is also considered. The validity of the developed method is demonstrated by comparing its results with those of 3D finite element analysis. The applications of the developed method to analyze five field test piles also show good agreement between the predictions and the experimental results. The developed method offers an alternative approach for simple and effective analysis of laterally loaded rigid piles in cohesive soil. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
14.
G. Habib 《新西兰海洋与淡水研究杂志》2013,47(4):755-766
Abstract The age of pufferfish Uranostoma richei (Freminville) in Lyttelton Harbour, South Island, New Zealand is described from analyses of length‐frequency distributions and growth zones in otoliths. Length‐frequency analysis is adequate only for aging smaller fish. The validity of using growth zones in otoliths is checked by examining the pattern and time of zone formation. Length‐weight relationships are established and growth rates calculated. Compared with males, females grow faster (2.4cm·y?1; 2.1 for males), attain a larger size (to 18 cm and 120 g; 12 cm and 40 g for males) and live longer (to 7 y; 5 for males). 相似文献
15.
Antti Pulkkinen Michael Hesse Shahid Habib Luke Van der Zel Ben Damsky Fritz Policelli David Fugate William Jacobs Elizabeth Creamer 《Natural Hazards》2010,53(2):333-345
In this paper, central elements of the Solar Shield project, launched to design and establish an experimental system capable
of forecasting the space weather effects on high-voltage power transmission system, are described. It will be shown how Sun–Earth
system data and models hosted at the Community Coordinated Modeling Center (CCMC) are used to generate two-level magnetohydrodynamics-based
forecasts providing 1–2 day and 30–60 min lead-times. The Electric Power Research Institute (EPRI) represents the end-user,
the power transmission industry, in the project. EPRI integrates the forecast products to an online display tool providing
information about space weather conditions to the member power utilities. EPRI also evaluates the economic impacts of severe
storms on power transmission systems. The economic analysis will quantify the economic value of the generated forecasting
system. The first version of the two-level forecasting system is currently running in real-time at CCMC. An initial analysis
of the system’s capabilities has been completed, and further analysis is being carried out to optimize the performance of
the system. Although the initial results are encouraging, definite conclusions about system’s performance can be given only
after more extensive analysis, and implementation of an automatic evaluation process using forecasted and observed geomagnetically
induced currents from different nodes of the North American power transmission system. The final output of the Solar Shield
will be a recommendation for an optimal forecasting system that may be transitioned into space weather operations. 相似文献
16.
Hassen Ouelhazi Fethi Lachaal Abdelkrim Charef Bilel Challouf Habib Chaieb Faten Jarraya Horriche 《Arabian Journal of Geosciences》2014,7(10):4407-4421
Korba aquifer is one of the most typical examples of overexploited coastal aquifer in the Mediterranean countries. In fact, from 1985, a considerable piezometric level drop, water salinization, and seawater intrusion were registered in the aquifer. In December 2008, Tunisian authorities initiated a general plan to groundwater management in order to augment groundwater resources, restore the piezometric levels, and improve water quality. The plan consists of artificial recharge of groundwater used treated wastewater through three infiltration basins. During the first 4 years (from December 2008 to December 2012), 1.41 Mm3 of treated wastewater was injected to the Korba aquifer. This study presents a hydrogeological assessment of groundwater evolution during the recharge processes. In this study, 32 piezometric and chemical surveys of 70 piezometers and observed wells are used to present hydrogeological investigation and water quality evolution of wastewater reuse through artificial recharge in Korba coastal aquifer. The piezometric evolution maps are used to specify the positive effect in groundwater level that exceeding 1.5 m in some regions. The interpretation of salinity evolution maps are used to indicate the improving of groundwater quality. 相似文献
17.
Mehdi Serati Habib Alehossein David J. Williams 《Rock Mechanics and Rock Engineering》2014,47(4):1087-1101
This paper investigates the application of a double Fourier series technique to the construction of an elastic stress field in a cylindrical bar subject to lateral boundary loads. The lateral loads, including the constant load boundary conditions, are represented by two Fourier series: one on the perimeter of the circular section (r 0, θ) and the other on the longitudinal curved surface parallel to the bar axis (z). The technique invokes acceptable potential functions of the Papkovich–Neuber displacement field, satisfying the governing partial differential equations, to assign appropriate odd and even trigonometric Fourier terms in cylindrical coordinates (r, θ, z). The generic solution decomposes the problem of interest to a state of stress caused by two independent boundary conditions along the z axis and θ-polar angle, both superimposed on a solution for which these potentials are the product of the trigonometric terms of the independent variables (θ, z). Constants appearing in the resultant second-order partial differential equations are determined from the generally mixed (tractions and/or displacements) boundary conditions. While the solutions are satisfied exactly at the ends of an infinite bar, they are satisfied weakly on average, in the light of Saint Venant’s approximation at the two ends of a finite bar. The application of the proposed analysis is verified against available elastic solutions for axisymmetric and non-axisymmetric engineering problems such as the indirect Brazilian Tensile Strength and Point Load Strength tests. 相似文献
18.
Ishfaq Ahmad Umer Saeed Muhammad Fahad Asmat Ullah M. Habib ur Rahman Ashfaq Ahmad Jasmeet Judge 《Journal of the Indian Society of Remote Sensing》2018,46(10):1701-1711
Real time, accurate and reliable estimation of maize yield is valuable to policy makers in decision making. The current study was planned for yield estimation of spring maize using remote sensing and crop modeling. In crop modeling, the CERES-Maize model was calibrated and evaluated with the field experiment data and after calibration and evaluation, this model was used to forecast maize yield. A Field survey of 64 farm was also conducted in Faisalabad to collect data on initial field conditions and crop management data. These data were used to forecast maize yield using crop model at farmers’ field. While in remote sensing, peak season Landsat 8 images were classified for landcover classification using machine learning algorithm. After classification, time series normalized difference vegetation index (NDVI) and land surface temperature (LST) of the surveyed 64 farms were calculated. Principle component analysis were run to correlate the indicators with maize yield. The selected LSTs and NDVIs were used to develop yield forecasting equations using least absolute shrinkage and selection operator (LASSO) regression. Calibrated and evaluated results of CERES-Maize showed the mean absolute % error (MAPE) of 0.35–6.71% for all recorded variables. In remote sensing all machine learning algorithms showed the accuracy greater the 90%, however support vector machine (SVM-radial basis) showed the higher accuracy of 97%, that was used for classification of maize area. The accuracy of area estimated through SVM-radial basis was 91%, when validated with crop reporting service. Yield forecasting results of crop model were precise with RMSE of 255 kg ha?1, while remote sensing showed the RMSE of 397 kg ha?1. Overall strength of relationship between estimated and actual grain yields were good with R2 of 0.94 in both techniques. For regional yield forecasting remote sensing could be used due greater advantages of less input dataset and if focus is to assess specific stress, and interaction of plant genetics to soil and environmental conditions than crop model is very useful tool. 相似文献
19.
20.
Habib Akbari‐Alashti Andrea Soncini Yagob Dinpashoh Ahmad Fakheri‐Fard Siamak Talatahari Daniele Bocchiola 《水文研究》2018,32(21):3254-3271
We assess the effects of prospective climate change until 2100 on water management of two major reservoirs of Iran, namely, Dez (3.34 × 109 m3) and Alavian (6 × 107 m3). We tune the Poly‐Hydro model suited for simulation of hydrological cycle in high altitude snow‐fed catchments. We assess optimal operation rules (ORs) for the reservoirs using three algorithms under dynamic and static operation and linear and non‐linear decision rules during control run (1990–2010 for Dez and 2000–2010 for Alavian). We use projected climate scenarios (plus statistical downscaling) from three general circulation models, EC‐Earth, CCSM4, and ECHAM6, and three emission scenarios, or representative concentration pathways (RCPs), RCP2.6, RCP4.5, and RCP8.5, for a grand total of nine scenarios, to mimic evolution of the hydrological cycle under future climate until 2100. We subsequently test the ORs under the future hydrological scenarios (at half century and end of century) and the need for reoptimization. Poly‐Hydro model when benchmarked against historical data well mimics the hydrological budget of both catchments, including the main processes of evapotranspiration and streamflows. Teaching–learning‐based optimization delivers the best performance in both reservoirs according to objective scores and is used for future operation. Our projections in Dez catchment depict decreased precipitation along the XXI century, with ?1% on average (of the nine scenarios) at half century and ?6% at the end of century, with changes in streamflows on average ?7% yearly and ?13% yearly, respectively. In Alavian, precipitation would decrease by ?10% on average at half century and ?13% at the end of century, with streamflows ?14% yearly and ?18% yearly, respectively. Under the projected future hydrology, reservoirs' operation would provide lower performance (i.e., larger lack of water) than now, especially for Alavian dam. Our results provide evidence of potentially decreasing water availability and less effective water management in water stressed areas like Northern Iran here during this century. 相似文献