Dynamic stability characteristics of liquid-filled shells     

Rasim Aziz Uras  Wing Kam Liu 《地震工程与结构动力学》1989,18(8):1219-1231

A Galerkin Finite Element formulation for the dynamic stability analysis of liquid-filled shells is given in this paper. The coupling among the axial and circumferential modes is investigated. The dynamic stability characteristics of two liquid-filled storage tanks subjected to vertical, horizontal and rocking seismic excitations are presented. It is shown that a tall tank tends to buckle at distinct frequencies; and for cos θ-type ground excitation, cos 2θ, cos 3θ and cos 4θ are the dominant modes of failure. On the other hand, in a broad tank, buckling regions overlap each other. In particular, for cos θ-type ground excitation, the dominant buckling modes are cos 6θ to cos 9θ, and also cos 12θ to cos 14θ.  相似文献   

Stochastic modelling of seasonal and yearly rainfalls with low-frequency variability   总被引：1，自引：1，他引：0  

Jing Lin?NgEmail author  Samsuzana?Abd Aziz  Yuk Feng?Huang  Aimrun?Wayayok  M.?K.?Rowshon 《Stochastic Environmental Research and Risk Assessment (SERRA)》2017,31(9):2215-2233

Stochastic rainfall models are important for many hydrological applications due to their appealing ability to simulate synthetic series that resemble the statistical characteristics of the observed series for a location of interest. However, an important limitation of stochastic rainfall models is their inability to preserve the low-frequency variability of rainfall. Accordingly, this study presents a simple yet efficient stochastic rainfall model for a tropical area that attempts to incorporate seasonal and inter-annual variabilities in simulations. The performance of the proposed stochastic rainfall model, the tropical climate rainfall generator (TCRG), was compared with a stochastic multivariable weather generator (MV-WG) in various aspects. Both models were applied on 17 rainfall stations at the Kelantan River Basin, Malaysia, with tropical climate. The validations were carried out on seasonal (monsoon and inter-monsoon) and annual basis. The third-order Markov chain of the TCRG was found to perform better in simulating the rainfall occurrence and preserving the low-frequency variability of the wet spells. The log-normal distribution of the TCRG was consistently better in modelling the rainfall amounts. Both models tend to underestimate the skewness and kurtosis coefficient of the rainfall. The spectral correction approach adopted in the TCRG successfully preserved the seasonal and inter-annual variabilities of rainfall amounts, whereas the MV-WG tends to underestimate the variability bias of rainfall amounts. Overall, the TCRG performed reasonably well in the Kelantan River Basin, as it can represent the key statistics of rainfall occurrence and amounts successfully, as well as the low-frequency variability.  相似文献   

Tigris River Sediments as Abrasive for Polishing Marble     

Awadh  Salih Muhammad  Khalid  Sara Ali 《Natural Resources Research》2019,28(4):1371-1383

Natural Resources Research - This study aims to evaluate the use of Tigris River sediments as abrasives for polishing marble surfaces to achieve a usable form as floor tiles, facing stones and...  相似文献   

Response of infilled frames using pseudo-dynamic experimentation     

Khalid M. Mosalam  Richard N. White  Gustavo Ayala 《地震工程与结构动力学》1998,27(6):589-608

An accurate and practical testing technique to study seismic performance of multi-storey infilled frames is formulated. This technique is based on the pseudo-dynamic method which can provide an acceptable approximation of the dynamic performance of structures under the influence of earthquake excitation. The pseudo-dynamic experimental technique is outlined and applied for testing a two-bay, two-storey gravity load designed steel frame infilled with unreinforced concrete block masonry walls. From the discussion of the results, the dynamic performance of the tested structure is assessed. © 1998 John Wiley & Sons, Ltd.  相似文献   

厦门西港表层沉积物中多环芳烃(PAHs)的含量分布特征及其污染来源   总被引：10，自引：0，他引：10  

张祖麟  王新红  哈里德  周俊良  陈伟琪  徐立  洪华生 《海洋通报》2001,20(1):35-39

利用GC－FID对厦门西港1998年7月采得8个站位表层沉积物中的16种多环芳烃（PAHs)进行了分析。结果显示，16种多环芳烃总量分布范围为247－480ng/g，平均为367ng/g。与1993年的厦门港的分析结果相比较，多环芳烃的污染程度降低；同世界其他港口相比较，其污染程度相对较低。同时，分析了厦门港PAHs污染的分布特征及其可能的污染来源，表明其主要是由于人类的油污染及燃料燃烧引起的。  相似文献   

Spatial-temporal changes of NDVI and their relations with precipitation and temperature in Yangtze River basin from 1981 to 2001     

Li Zhang  Xiaoling Chen  Xiaobin Cai  Habib Aziz Salim 《地球空间信息科学学报》2010,13(3):186-190

Multitemporal NOAA/AVHRR NDVI images and monthly temperature and precipitation data were obtained across Yangtze River basin covering the period 1981–2001. The spatial and temporal patterns of NDVI are the same, while spatial analysis shows that the NDVI is influenced by the vegetation types growing in the study regions, and NDVI presents an increasing trend during the study period in the whole basin. The climate indicators play an important role in the changes of vegetation cover in the river basin. In the two Indicators, temperature has a significant effect on the NDVI values than precipitation in the whole basin. However, in the 11 subbasins, the different rules are shown in different subbasins.  相似文献   

Organic compound tracers of fine soil and sand particles during summer in the metropolitan area of Riyadh,Saudi Arabia     

Khalid Al-Mutlaq  Ahmed I. Rushdi  Bernd R. T. Simoneit 《Environmental Geology》2007,52(3):559-571

Soil and sand fine particles, which may be resuspended as fine dust in the atmosphere, contain a variety of anthropogenic and natural organic components. Samples of fine soil and sand particles (sieved to <125 μM) were collected from the Riyadh area in the summer of 2003 and extracted with a mixture of dichloromethane and methanol (3:1, v:v). The derivatized total extracts were analyzed by gas chromatography–mass spectrometry in order to characterize the composition and sources of the organic components. Both anthropogenic and natural biogenic inputs were the major sources of the organic compounds in these extracts. Discarded plastics and vehicular emission products were the major anthropogenic sources in the fine particles from populated areas of the city. Their tracers were plasticizers, UCM, n-alkanes, hopanes and traces of steranes. Vegetation was the major natural source of organic compounds in samples from outside Riyadh and included n-alkanols, n-alkanoic acids, n-alkanes, methyl alkanoates, sterols and triterpenoids. Carbohydrates had high concentrations (42–54%) in all samples and indicate sources from decomposition of cellulose and/or the presence of viable microbiota such as bacteria and fungi. The results were also compared with the data obtained in winter 2002 and showed that anthropogenic inputs were higher in summer than in winter, whereas the opposite trend was observed for natural inputs.  相似文献   

Preliminary evidence of a link between surface soil properties and the arsenic content of shallow groundwater in Bangladesh     

A. van Geen  Z. Aziz  A. Horneman  B. Weinman  R.K. Dhar  Y. Zheng  S. Goodbred  R. Versteeg  A.A. Seddique  M.A. Hoque  K.M. Ahmed 《Journal of Geochemical Exploration》2006,88(1-3):157

The extremely heterogeneous distribution of As in Bangladesh groundwater has hampered efforts to identify with certainty the mechanisms that lead to extensive mobilization of this metalloid in reducing aquifers. We show here on the basis of a high-resolution transect of soil and aquifer properties collected in Araihazar, Bangladesh, that revealing tractable associations between As concentrations in shallow (< 20 m) groundwater with other geological, hydrological, and geochemical features requires a lateral sampling resolution of 10–100 m. Variations in the electromagnetic conductivity of surface soils (5–40 mS/m) within a 500 m × 200 m area are documented with 560 EM31 measurements. The results are compared with a detailed section of groundwater As concentrations (5–150 μg/L) and other aquifer properties obtained with a simple sampling device, “the needle-sampler”, that builds on the local drilling technology. By invoking complementary observations obtained in the same area and in other regions of Bangladesh, we postulate that local groundwater recharge throughout permeable sandy soils plays a major role in regulating the As content of shallow aquifers by diluting the flux of As released from reducing sediments.  相似文献   

Evaluation of the potential of friction surface analysis in modelling hurricane wind damage in an urban environment     

Robin I. Knight  Fakhar Khalid 《Natural Hazards》2015,76(2):891-911

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A New Spectral Index for Extraction of Built-Up Area Using Landsat-8 Data     

Sara Bouzekri  Abdel Aziz Lasbet  Ammar Lachehab 《Journal of the Indian Society of Remote Sensing》2015,43(4):867-873

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