Dynamic response of pipelines to moving loads     

S. K. Datta  T. Chakraborty  A. H. Shah 《地震工程与结构动力学》1984,12(1):59-72

Vibration of buried pipelines induced by moving axial and radial loads has been studied in this paper. A thin shell model has been used for the pipeline, which is assumed to be lying in an infinite isotropic homogeneous elastic medium. In order to allow for the possible motion of the pipe out of phase with the surrounding ground a very thin layer of viscoelastic material is assumed to separate the pipe from the ground. Calculations indicate the presence of the interfacial viscoelastic layer does not influence the pipe response in a significant manner. So all the numerical results presented here are for the case when the pipe is assumed to be perfectly bonded. These show that the maximum pipewall displacements and stresses occur in a soft soil at long wavelengths.  相似文献   

Effect of biodiesel on particulate numbers and composition emitted from turbocharged diesel engine     

A. N. Shah  G. Yun-shan  F. H. Shah  H. U. Mughal  Z. u. Rahman  A. Naveed 《International Journal of Environmental Science and Technology》2014,11(2):385-394

In present study a turbocharged, medium duty compression ignition engine was alternatively fuelled with biodiesel to investigate the changes in particulate matter composition, relative to that taken with diesel fuel. The engine was operated on an AC electrical dynamometer in accordance with an 8-mode, steady-state cycle. The numbers of particles were estimated through electrical low pressure impactor, while sulfates and trace metals were analyzed by ion chromatography and inductively coupled plasma-atomic emission spectroscopy, respectively. Nitric oxides and nitrogen dioxides were measured separately using SEMTECH-DS. Experimental results revealed that, on account of elevated ratios of nitrogen dioxide to nitrogen oxides, mean accumulation mode particles were 42 % lower with biodiesel. On the other hand, nuclei mode particles were higher with biodiesel, owing to heterogeneous nucleation and accounting for an increase in sulfate emissions up to 8 % with biodiesel as compared to diesel. On the average, trace metal emissions were significantly reduced showing 65–85.4 % reduction rates with biodiesel, relative to its counterpart. Further to this, individual congeners such as iron, calcium, and sodium were the predominant elements of the trace metals emitted from engine. The mean relative decrease in iron and calcium was 89–97.8 and 77.6–87 %, respectively, while the relative rise in sodium was in the range of 29–46 % with biodiesel. Further, elements such as zinc, chromium, and aluminum showed substantial abatement, whereas potassium, magnesium, and manganese exhibited irregular trends on account of variable engine loads and speeds during the various modes of cycle.  相似文献   

Geochemical characteristics of water and sediment from the Dal Lake, Kashmir Himalaya: constraints on weathering and anthropogenic activity     

G. Jeelani  A. Q. Shah 《Environmental Geology》2006,50(1):12-23

Two hundred and forty water samples (in four seasons) and seventeen sediment samples have been analyzed to monitor the natural and anthropogenic influences on the water and sediment chemistry of the Dal Lake, Kashmir Himalaya. The scatter diagrams [(Ca+Mg)/total cations (TZ⁺), (Ca+Mg)/HCO₃, (Ca+Mg)/(HCO₃₊SO₄), (Na+K)/TZ⁺; (Ca+Mg)/(Na+K)] and the geological map of the study area suggest predominance of carbonate and silicate weathering. Lower pH and high total dissolved solids, electrical conductivity and values in the Gagribal basin and in some patches of other basins reflect anthropogenic inputs in the form of sewage from surrounding population, houseboats, hotels, etc. The Dal Lake is characterized by high chemical index of alteration (CIA: 87–95), reflecting extreme weathering of the catchment area. Relative to the average carbonates, the lakebed sediments are enriched in Al, Ti, Zn, Cu and Co and depleted in Ni and Mn. Compared to the post-Archean Shale the sediments have higher Al, Zn and Cu contents and lower Ni and Co. There are distinct positive anomalies of Al, Mn, Zn and Cu and negative anomalies of Ni and Pb with respect to the upper continental crust. Geoaccumulation index (I _geo) and the US Environmental Protection Agency sediment quality standards indicate that the Gagribal basin and some patches of the Nagin basin are polluted with respect to Zn, Cu and Pb. These data suggest that the Dal Lake is characterized by differential natural and anthropogenic influences.  相似文献   

Structural interpretation and hydrocarbon potential of Balkassar oil field,eastern Potwar,Pakistan, using seismic 2D data and petrophysical analysis     

Syed Bilawal Ali Shah  Wan Hasiah Abdullah 《Journal of the Geological Society of India》2017,90(3):323-328

The Balkassar oil field is situated in the eastern Potwar sub-basin, lies on the southern flank of Soan syncline in Himalayan collisional regime. The area represents Indo-Pak and Eurasian blocks of Precambrian to recent time. Thrusting and folding of Himalayan, Indo-Pak plate movement and Salt Range uplift form the structural trap in Balkassar sub-surface (Balkassar anticline). On the basis of information from eleven seismic 2D lines and wells data six reflectors well data, four faults were identified and marked. The structural trend is northeast southwest. Interpretation of seismic 2D data reveals that the study area has undergone intense deformation as a consequence of development of thrusts and backthrusts.The Balkassar anticline is bounded by two thrust faults one from southeast and the other from northwest. Time and depth contour models shows that anticline limbs at north-western side are steep as compared to south-eastern limbs. Seismic interpretation indicates the presence of well-developed anticline bounded by three faults in the cover sequence and one fault in basement and thus the structure may act as a trap for hydrocarbons. The petrophysical analysis of Balkassar-OXY-1 well shows about 83.1% hydrocarbons saturation in the reservoir rocks, hence this study suggest that Balkassar Oilfield has potential to produce hydrocarbons.  相似文献   

GPR survey and physical measurements of sea ice in Quilty Bay,Larsemann hills,East Antarctica and its correlation with local atmospheric parameters     

Mohd Yunus Shah  Kato K. Ayemi  Prakash Kumar Shrivastava 《Journal of the Geological Society of India》2017,90(3):371-377

Sea ice formation in Quilty Bay, East Antarctica shows a strong relationship with climatic conditions and its spatial variation is established by GPR survey over the sea ice during the austral winters. The study also evaluates the variability of sea ice thickness and extent with local weather parameters between 2010 and 2014. Profiling on sea ice in Quilty Bay shows that sea ice thickness decreases gradually towards east. The overall thickness of sea ice is considerably less at the centre of the bay as compared to the coastal side. Two types of fast ice layers have been delineated from GPR surveys i.e. top layer fast ice which incorporates very low density surface snow and underlying high density fast ice i.e. with melt water pockets. Development of sea ice is influenced by persistent easterly winds, temperature fluctuations and ocean currents. Sea ice reveal average annual cyclic trend in Quilty Bay with maximum development in the year 2013 (157.54 cm) and the minimum development has been observed in the year 2010 (99.04 cm).The cyclic pattern of average sea ice accumulation data show perfect inverse correlation with surface air temperature, with measure of reliability R² = 0.93. However, moderate (R² = 0.52) and good (R² = 0.69) degree of inverse relationship is observed with surface snow and overall sea ice (snow and ice) respectively. With 0.46 °C change in temperature, there is 33% change in sea ice condition in Quilty Bay which may remain same as far as ice extents in the region. Besides this easterly winds play a vital role in controlling the snow/ice distribution patterns as reflected by isopach maps.  相似文献   

Diatoms,spatial distribution and physicochemical characteristics of the Wular lake sediments,Kashmir valley,Jammu and Kashmir     

Rayees Ahmad Shah  Hema Achyuthan  Aasif Mohmad Lone  R. Ramanibai 《Journal of the Geological Society of India》2017,90(2):159-168

Lakes and wetlands are dynamic geomorphic units of a landscape that hold geochemical signatures of sediment provenance and paleo-environmental shifts and are major sinks for organic matter accumulation. The source of organic matter is diverse in lake sediments and varies widely with the type and size of the lake and hence it is important to understand the source of organic carbon (terrestrial or in situ) in lake systems in order to monitor the health of the lake. Wular lake, located in north Kashmir, is one of the largest fresh water lake in India, situated at an average elevation of 1580m ASL. The lake is fed by a number of watersheds that bring a diverse type of sediments and organic matter and thus deposit them into the Wular lake basin. In order to understand sediment distribution pattern, content and source of organic matter, sediment provenance and the persisting environment in the Wular lake, 32 lake floor sediment samples covering the entire lake were collected and analyzed for organic element analysis, CaCO3, organic matter, sediment texture and diatom analysis. The results indicated that sediments in the lake are dominated by silt and silty clay. The organic carbon in the lake ranged from 0.83%-4.52% and nitrogen varied from 0.06%-0.5%. The Carbon to Nitrogen (C/N) ratios (9.04 to 22.03) indicate a mixed source of organic carbon but dominated by in situ lake sources from the vascular and lake biota accumulation. The diatom analysis revealed the occurrence of a diverse type of species along the sampling sites present within the lake. The wide distribution of the diatom species such as Cymbella, Cyclotella and Tabularia etc. in the lake indicate high organic pollution and alkaline fresh water environment prevailing in the lake.  相似文献   

Disaster risk management in agriculture: tragedies of the smallholders     

Raza Ullah  Ganesh P. Shivakoti  Farhad Zulfiqar  Muhammad Nadeem Iqbal  Ashfaq Ahmad Shah 《Natural Hazards》2017,87(3):1361-1375

Agriculture sector is exposed to a variety of risks and uncertainties which can lead to sizeable losses in crop yields and alter farm incomes. Risk management is, therefore, an essential element of the overall farm management process. Farmers have number of options in managing farm risks; however, smallholders, due to their small operations and limited financial capabilities, find it difficult to adopt sophisticated risk management strategies to overcome yield and income instabilities at farm level. This study is, therefore, designed to investigate the enabling environment for small farmers to manage climatic risks at farm level. A total of 330 sampled respondents from Khyber Pakhtunkhwa Province of Pakistan are randomly selected for the study using multistage sampling technique. Analysis of variance technique is employed to compare the risk management adoption decision of small, medium and large farmers. A post hoc analysis is also performed to highlight the difference in means and the magnitude of differences. The results indicate that smallholders have significantly lower access to credit (both formal and informal), formal information sources along with significantly higher perceptions of pest and diseases. Smallholders are also at the tail end in the adoption of precautionary savings and agricultural credit to manage climatic risk at farm level. The study urges for risk management policies particularly in favor of the small farmers and intervention in the existing information and credit provision programs to facilitate smallholders in managing farm risks.  相似文献   

Segmentation of Main Boundary Thrust and Main Central Thrust in Western Himalaya for assessment of seismic hazard by Mridula et al., Nat Hazards (2016) 84: 383–403     

Shah  A. A.  Talha Qadri  S. M. 《Natural Hazards》2017,87(2):1245-1249

Natural Hazards - Mridula et al. (Nat Hazards 84:383–403, (2016) have tried to identify segments of two major thrust faults, the Main Boundary Thrust and Main Central Thrust, in Western...  相似文献   

Optical colours and polarization of a model reflection nebula. II. Silicate and graphite grains in a nebula with the star in the rear     

G. A. Shah 《Astronomische Nachrichten》1977,298(6):319-325

The colour difference between the star and the attendant reflection nebula and polarization both caused by silicate and graphite grains have been given. The properly normalized size distribution function for each type of grains has been considered within homogeneous plane parallel slab-model of the reflection nebula with the star in the rear. Contrary to some earlier results, it has been possible to show that silicate grains can certainly play a role in the phenomena of reflection nebulae.  相似文献   

Full-scale experimental investigations on the response of a flooded passenger vehicle under subcritical conditions     

Al-Qadami  Ebrahim Hamid Hussein  Mustaffa  Zahiraniza  Shah  Syed Muzzamil Hussain  Matínez-Gomariz  Eduardo  Yusof  Khamaruzaman Wan 《Natural Hazards》2022,110(1):325-348

Natural Hazards - Vehicles can be easily swept away by floodwaters once the flow velocity and depth reach certain critical limits, with probabilities toward fatality reported to be nearly 50%....  相似文献