Simulation of vortex-induced vibrations of a cylinder using ANSYS CFX   总被引：1，自引：0，他引：1  

Abu Bakar Izhar  Arshad Hussain Qureshi  Shahab Khushnood 《中国海洋工程》2014,28(4):541-556

In this paper, vortex-induced vibrations of a cylinder are simulated by use of ANSYS CFX simulation code. The cylinder is treated as a rigid body and transverse displacements are obtained by use of a one degree of freedom spring damper system. 2-D as well as 3-D analysis is performed using air as the fluid. Reynolds number is varied from 40 to 16000 approx., covering the laminar and turbulent regimes of flow. The experimental results of （Khalak and Williamson, 1997） and other researchers are used for validation purposes. The results obtained are comparable.  相似文献   

Building population mapping with aerial imagery and GIS data     

Serkan Ural  Ejaz Hussain  Jie Shan 《International Journal of Applied Earth Observation and Geoinformation》2011

Geospatial distribution of population at a scale of individual buildings is needed for analysis of people's interaction with their local socio-economic and physical environments. High resolution aerial images are capable of capturing urban complexities and considered as a potential source for mapping urban features at this fine scale. This paper studies population mapping for individual buildings by using aerial imagery and other geographic data. Building footprints and heights are first determined from aerial images, digital terrain and surface models. City zoning maps allow the classification of the buildings as residential and non-residential. The use of additional ancillary geographic data further filters residential utility buildings out of the residential area and identifies houses and apartments. In the final step, census block population, which is publicly available from the U.S. Census, is disaggregated and mapped to individual residential buildings. This paper proposes a modified building population mapping model that takes into account the effects of different types of residential buildings. Detailed steps are described that lead to the identification of residential buildings from imagery and other GIS data layers. Estimated building populations are evaluated per census block with reference to the known census records. This paper presents and evaluates the results of building population mapping in areas of West Lafayette, Lafayette, and Wea Township, all in the state of Indiana, USA.  相似文献   

Underwater glider modelling and analysis for net buoyancy, depth and pitch angle control     

Nur Afande Ali Hussain  Rosmiwati Mohd-Mokhtar 《Ocean Engineering》2011,38(16):1782-1791

Underwater glider is an autonomous underwater vehicle that glides by controlling their buoyancy and attitude using internal actuators. By changing the vehicle's buoyancy intermittently, vertical motion can be achieved. Characteristics of glider motion include upward and downward movement in a saw tooth pattern, turning and gliding in a vertical spiral motion and gliding without using thrusters or propellers. This paper presents the modelling and identification on net buoyancy, depth and pitching angle of an underwater glider system. A ballast tank subsystem is considered appropriate for the identification process since it is the main parameter for the motion control. By selecting the ballast rate as the input, three aspects of the dynamics of a glider can be observed: buoyancy, depth of the glider and pitching angle. The MATLAB System Identification Toolbox^TM is used to obtain a mathematical model of the glider ballast-buoyancy, ballast-depth and ballast-pitching angle conditioning system. The best three parametric estimation models are chosen, and the results of the comparison between simulated and estimated outputs are presented. The information obtained from the modelling and identification approaches are used for USM's Underwater Glider Prototype controller design. The information observed during this procedure are utilised for optimisation, stability, reliability and robustness analysis of the underwater glider.  相似文献   

Mapping potential fields on the surfaces of rapidly rotating stars     

G. A. J. Hussain  M. Jardine  A. Collier Cameron 《Monthly notices of the Royal Astronomical Society》2001,322(3):681-688

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Palaeomagnetism of the basalts of Wadi Abu Tereifiya, Mandisha and dioritic dykes of Wadi Abu Shihat, Egypt     

A. Gouda Hussain  A. Schult  H. Soffel 《Geophysical Journal International》1979,56(1):55-61

Summary. One hundred and fifty oriented samples were collected from 12 sites from the Tertiary basalts of Wadi Abu Tereifiya (30.0°N, 32.1° E). After alternating field demagnetization the mean direction of the natural remanent magnetization is, D = 187.9°, I = -20.8° with α₉₅= 5.8°. This yields a palaeopole at 69.4°N, 188.3° E.
Also, 30 oriented samples were collected from two sites from Mandisha in Bahariya Oasis (28.4°N, 28.9° E). After cleaning, the mean direction of the NRM is D = 191.0°, I = 5.2° with α₉₅= 9.9°. This yields a palaeopole position at 58.2°N, 186.7° E.
Besides, the NRM of 70 oriented samples collected from seven dioritic dykes from Wadi Abu Shihat (26.3°N, 33.2° E) was found to have a mean direction, D = 142.0°, I = -0.3°, which leads to a palaeopole position at, 44.9°N, 273.0° E. This agrees with other Mesozoic pole positions from Africa.  相似文献   

Petrology and Mineral Chemistry of Lower Crustal Intrusions: the Chilas Complex, Kohistan (NW Pakistan)   总被引：6，自引：0，他引：6  

Jagoutz  Oliver; Muntener  Othmar; Ulmer  Peter; Pettke  Thomas; Burg  Jean-Pierre; Dawood  Hamid; Hussain  Shahid 《Journal of Petrology》2007,48(10):1895-1953

Mineral major and trace element data are presented for the mainrock units of the Chilas Complex, a series of lower crustalintrusions emplaced during initial rifting within the MesozoicKohistan (paleo)-island arc (NW Pakistan). Detailed field observationsand petrological analysis, together with geochemical data, indicatethat the two principal units, ultramafic rocks and gabbronoritesequences, originate from a common parental magma, but evolvedalong different mineral fractionation trends. Phase petrologyand mineral trace element data indicate that the fractionationsequence of the ultramafic rocks is dominated by the crystallizationof olivine and clinopyroxene prior to plagioclase, whereas plagioclaseprecedes clinopyroxene in the gabbronorites. Clinopyroxene inthe ultramafic rocks (with Mg-number [Mg/(Fe_tot + Mg] up to0·95) displays increasing Al₂O₃ with decreasing Mg-number.The light rare earth element depleted trace element pattern(Ce_N/Gd_N 0·5–0·3) of primitive clinopyroxenesdisplays no Eu anomaly. In contrast, clinopyroxenes from thegabbronorites contain plagioclase inclusions, and the traceelement pattern shows pronounced negative anomalies for Sr,Pb and Eu. Trace element modeling indicates that in situ crystallizationmay account for major and trace element variations in the gabbronoritesequence, whereas the olivine-dominated ultramafic rocks showcovariations between olivine Mg-number and Ni and Mn contents,pointing to the importance of crystal fractionation during theirformation. A modeled parental liquid for the Chilas Complexis explained in terms of mantle- and slab-derived components,where the latter component accounts for 99% of the highly incompatibleelements and between 30 and 80% of the middle rare earth elements.The geochemical characteristics of this component are similarto those of a low percentage melt or supercritical liquid derivedfrom subducted mafic crust. However, elevated Pb/Ce ratios arebest explained by additional involvement of hydrous fluids.In accordance with the crystallization sequence, the subsolidusmetamorphic reactions indicate pressures of 0·5–0·7GPa. Our data support a model of combined flux and decompressionmelting in the back-arc. KEY WORDS: Kohistan; Island arc; gabbro; trace element modelling; lower crustal intrusion  相似文献   

Temporal variation of physico-chemical parameters and ostracoda population,off Rameswaram,Gulf of Mannar,southeast coast of Tamil Nadu,India     

K. Baskar  S. G. D. Sridhar  T. Sivakumar  S. M. Hussain  S. Maniyarasan 《Journal of the Geological Society of India》2015,86(6):663-670

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Secular Variation of Geomagnetic Field at Karachi Observatory     

Hussain  Sumrah  Khan  Muhammad Nehal 《Geomagnetism and Aeronomy》2021,61(8):1234-1239

Geomagnetism and Aeronomy - In this work, the secular variation of noon/midnight geomagnetic observed field has been investigated at Karachi observatory using the data of total geomagnetic field...  相似文献   

Assessment of land use/land cover dynamics vis-à-vis hydrometeorological variability in Wular Lake environs Kashmir Valley,India using multitemporal satellite data     

Fayma Mushtaq  Arvind Chandra Pandey 《Arabian Journal of Geosciences》2014,7(11):4707-4715

Wular Lake, one of the largest freshwater lakes of Jhelum River Basin, is showing signs of deterioration due to the anthropogenic impact and changes in the land use/land cover (LULC) and hydrometeorological climate of the region. The present study investigated the impacts of temporal changes in LULC and meteorological and hydrological parameters to evaluate the current status of Wular Lake environs using multisensor, multitemporal satellite and observatory data. Satellite images acquired for the years 1992, 2001, 2005, and 2008 were used for determining changes in the LULC in a buffer area of 5 km² around the Wular Lake. LULC mapping and change analysis using the visual interpretation technique indicated significant changes around the Wular Lake during the last two decades. Reduction in lake area from 24 km² in 1992 to 9 km² in 2008 (?62.5 %) affected marshy lands, the habitat of migratory birds, which also exhibited drastic reduction from 85 km² in 1992 to 5 km² in 2008 (?94.117 %). Marked development of settlements (642.85 %) in the peripheral area of the Wular Lake adversely affected its varied aquatic flora and fauna. Change in climatic conditions, to a certain extent, is also responsible for the decrease in water level and water spread of the lake as witnessed by decreased discharge in major tributaries (Erin and Madhumati) draining into the Wular Lake.  相似文献   

Evaluation of natural resource potential in semi-arid micro-watershed, eastern Rajasthan, using remote sensing and geographic information system     

Mushtaq Hussain Wani  Akram Javed 《Arabian Journal of Geosciences》2013,6(6):1843-1854

The natural resources are considered more efficient and appropriate for necessary survey and investigation for the assessment, subsequent planning and implementation of various developmental programmes. Hence, it is necessary to increase the land and water resources levels for future demands. Morphometric, land use/land cover and hydrogeomorphic analyses have been carried out by visual interpretation method of remote sensing data of IRS, 1D-LISS III and IRS, P6-LISS III, and FCCs of band combination 2, 3 and 4. The interpreted data is supplemented as well as cross checked by field visits. The remote sensing and GIS tool could be helpful in getting the precise and valuable spatial information in understanding the present scenario contemplating with the past data and predicting the future trends. Morphometric analysis was done to determine the drainage characteristics of Bankukara watershed. The drainage pattern of the study area is predominantly dendritic to sub-dendritic in nature; however, locally structurally controlled drainage pattern is also seen. The development of stream segments is affected by slope and local relief. The bifurcation ratio indicates that the drainage pattern is structurally controlled. The land use/land cover change detection for 2001 and 2005 showed an increase in uncultivated land by 1.37%, dense forest by 0.17%, wasteland by 1.46% and rock quarry by 0.10%. There has been a decrease in the area under cultivated land by 1.99%, open forest by 0.12%, open scrub by 0.54% and water body by 0.40%. Hydrogeomorphic units identified through visual interpretation of FCC include alluvial plain, valley fills, plateau, buried pediment, pediments and intermontane. Based on land use/land cover change detection and hydrogeomorphological mapping, the Bankukara watershed has qualitatively been categorized into four groundwater potential zones, viz. good to very good, moderate to good, poor to moderate and very poor to poor.  相似文献