Earthquake-resistant design according to the most unfavourable seismic direction under combined internal forces     

Adnan lakirolu 《地震工程与结构动力学》1987,15(7):853-864

In this study it has been shown that, in the case of linear theory, the combined internal forces corresponding to each seismic direction lie on an ellipsoid having internal forces chosen as the set of axes. A method is proposed to obtain the most unfavourable results easily, in the neighbourhood of the several unfavourable points without actually determining the ellipsoid. The design can be carried out using linear, as well as non-linear, theory. Two examples are given to illustrate the application of the proposed method.  相似文献   

Assessment of Air Temperature Trends in the Source Region of Yellow River and Its Sub-Basins,China     

Mudassar Iqbal  Jun Wen  Xin Wang  Yongchao Lan  Hui Tian  Muhammad Naveed Anjum  Muhammad Adnan 《Asia-Pacific Journal of Atmospheric Sciences》2018,54(1):111-123

Changes in climatic variables at the sub-basins scale (having different features of land cover) are crucial for planning, development and designing of water resources infrastructure in the context of climate change. Accordingly, to explore the features of climate changes in sub-basins of the Source Region of Yellow River (SRYR), absolute changes and trends of temperature variables, maximum temperature (Tmax), minimum temperature (Tmin), mean temperature (Tavg) and diurnal temperature range (DTR), were analyzed annually and seasonally by using daily observed air temperature dataset from 1965 to 2014. Results showed that annual Tmax, Tmin and Tavg for the SRYR were experiencing warming trends respectively at the rate of 0.28, 0.36 and 0.31°C (10 yr)^?1. In comparison with the 1st period (1965-1989), more absolute changes and trends towards increasing were observed during the 2nd period (1990-2014). Apart from Tangnaihai (a low altitude sub-basin), these increasing trends and changes seemed more significant in other basins with highest magnitude during winter. Among sub-basins the increasing trends were more dominant in Huangheyan compared to other sub-basins. The largest increase magnitude of Tmin, 1.24 and 1.18°C (10 yr)^?1, occurred in high altitude sub-basins Jimai and Huangheyan, respectively, while the smallest increase magnitude of 0.23°C (10 yr)^?1 occurred in a low altitude sub-basin Tangnaihai. The high elevation difference in Tangnaihai probably was the main reason for the less increase in the magnitude of Tmin. In the last decade, smaller magnitude of trend for all temperature variables signified the signal of cooling in the region. Overall, changes of temperature variables had significant spatial and seasonal variations. It implies that seasonal variations of runoff might be greater or different for each sub-basin.  相似文献   

Comparative assessment of spatiotemporal snow cover changes and hydrological behavior of the Gilgit,Astore and Hunza River basins (Hindukush–Karakoram–Himalaya region,Pakistan)     

Adnan Ahmad Tahir  Jan Franklin Adamowski  Pierre Chevallier  Ayaz Ul Haq  Silvia Terzago 《Meteorology and Atmospheric Physics》2016,128(6):793-811

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Hydrologic response to future land use change in the Upper Mississippi River Basin by the end of 21st century   总被引：1，自引：0，他引：1       下载免费PDF全文

Adnan Rajib  Venkatesh Merwade 《水文研究》2017,31(21):3645-3661

This study demonstrates the spatial variation in hydrologic processes across the Upper Mississippi River Basin (UMRB) by the end of 21st century, by ingesting FOREcasting Scenarios (FORE‐SCE) of Land‐use Change projections into a physics‐based hydrologic model—Soil and Water Assessment Tool. The model is created for UMRB (440,000 km²), using the National Landcover Database of year 2001 and climate data of 1991–2010. Considering 1991–2010 as the baseline reference period, FORE‐SCE projections of year 2091 under three scenarios (A1B, A2, and B1 from the Intergovernmental Panel on Climate Change) are separately assimilated into the calibrated model, whereas climate input is kept the same as in the baseline. Modeling results suggest an increase of 0.5% and 3.5% in the average annual streamflow at the basin outlet (Grafton, Illinois) during 2081–2100, respectively, for A1B and A2, whereas for B1, streamflow would decrease by 1.5%. Under the “worst case” A2 scenario, 6% and 133% increase, respectively, in agricultural and urban areas with 30% depletion of forest and grassland would result into 70% increase in surface runoff, 20% decrease in soil moisture, and 4% decrease in evapotranspiration in certain parts of the basin. Conversion of cropland, forest, or grassland to perennial hay/pasture areas would lower surface runoff by 25% especially in the central region, whereas persistent forest cover in the northern region would cause up to 7% increase in evapotranspiration. The ecosystem in the lower half of UMRB is likely to become adverse, as dictated by a composite water–energy balance indicator. Future land use change extents and resultant hydrologic responses are found significantly different under A2, A1B, and B1 scenarios, which resonates the need for multi‐scenario ensemble assessments towards characterizing a probable future. The spatial variation of hydrologic processes as shown here helps to identify potential “hot spots,” giving ways to adopt more effective policy alternatives at regional level.  相似文献   

Thermal shock weakening of granite rock under dynamic loading: 3D numerical modeling based on embedded discontinuity finite elements     

Timo Saksala  Adnan Ibrahimbegovic 《国际地质力学数值与分析法杂志》2020,44(13):1788-1811

This paper presents a numerical study of thermal shock weakening of granite rock under dynamic loading. A fully 3D numerical scheme based on a combined continuum viscodamage-embedded discontinuity model and an explicit scheme to solve the underlying thermomechanical problem was developed and validated through numerical examples. First, the dynamic Brazilian disc test is simulated on intact numerical rock. Then, thermal shock-induced cracking due to a moving external heat flux boundary condition, mimicking experiments based on plasma jet treatment, is numerically predicted. Finally, numerical Brazilian disc test is conducted on the thermal shocked numerical samples. The predicted and experimental weakening effects are in good agreement demonstrating that the present modeling approach has good predictive capabilities. The practical significance of the results is that heat shock pretreatment can substantially enhance rock gravel and rubble crushing.  相似文献   

Analyzing the occurrence of floods and droughts in connection with climate change in Punjab province,Pakistan     

Ali  Syeda Maria  Khalid  Bushra  Akhter  Asma  Islam  Aneeza  Adnan  Shahzada 《Natural Hazards》2020,103(2):2533-2559

Natural Hazards - Frequency and intensity of extreme weather events are immensely changing throughout the world. This study aims to give insight into the changing climatic patterns leading to...  相似文献   

RFI profiles of prime candidate sites for the first radio astronomical telescope in Malaysia     

Zamri Zainal Abidin  Syed Bahari Ramadzan Syed Adnan  Zainol Abidin Ibrahim 《New Astronomy》2010,15(3):307-312

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Rare earth element (REE) geochemistry and genetic implications of the Morta? bauxite deposit (Seydi?ehir/Konya - Southern Turkey)     

M. Muzaffer Karada?  Veysel Zedef  Adnan Döyen 《Chemie der Erde / Geochemistry》2009,69(2):143-159

The Mediterranean-type karst-bauxite deposit of Morta?, south Turkey, placed unconformably between Cenomanian and Senonian shallow marine limestones is built of massive (MB), oolithic (OB), breccia-bearing (BB) and earthy (EB) bauxite horizons, from top to bottom. The MB layer is enriched in Al and REE (except Ce) due to loss of Si, Na, K, Mg and P. REE are accumulated in the BB but depleted in the EB layers. The ferruginous OB lost LREE and gained in HREE probable due to scavenging by authigenic heavy minerals like rutile, anatase and titanite. Total REE contents in the bauxite profile display an increasing trend from bottom to top, while negative and maximum positive Ce anomalies characterize the upper and the lower parts of the profile, respectively. This unusual REE behavior is explicable by assuming mobilization of Ce(IV) either under reducing condition or chemical complexation under alkaline conditions in the top layer and scavenging of Ce by Al-Mg hydrosilicates and Ti-oxides and/or precipitation with authigenic REE minerals, especially of the bastnäsite group near the bedrock limestones. Similarity in chondrite normalized-REE patterns of the Seydi?ehir phyllites, bauxite and terra rossa samples and the presence of tridymite (?) in bauxites makes a felsic source rock most likely and reveal a close genetic relationship between the Seydi?ehir phyllites and the recent terra rossa occurrences. The REE patterns of the bauxites resemble those of the Katrangedi?i limestone despite variations in ΣREE. Field observations and geochemical data together with mass-balance calculations suggest that the Morta? deposit was derived from the Seydi?ehir phyllites and argillic phase within the Katrangedi?i limestone which in turn have Precambrian (?) felsic, probably granitic precursors.  相似文献   

Small amplitude two dimensional electrostatic excitations in a magnetized dusty plasma with q-distributed electrons     

Shahab Ullah Khan  Muhammad Adnan  Anisa Qamar  Shahzad Mahmood 《Astrophysics and Space Science》2016,361(7):213

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Erratum: The role of in situ stress in determining hydraulic connectivity in a fractured rock aquifer (Australia)     

Luke Mortimer  Adnan Aydin  Craig T. Simmons  Graham Heinson  Andrew J. Love 《Hydrogeology Journal》2011,19(7):1453-1453

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