Discussion of “The effect of energy concentration of earthquake ground motions on the nonlinear response of RC structures” by H. Cao,M.I. Friswell     

Abbas Moustafa 《Soil Dynamics and Earthquake Engineering》2009

This discussion raises a few comments and questions on the paper by Cao and Friswell [Cao H, Friswell MI. The effect of energy concentration of earthquake ground motions on the nonlinear response of RC structures. Soil Dyn Earthquake Eng 2009; 29: 292–9.]. The authors consider an interesting problem on seismic response analysis of nonlinear structures. Specifically, the study examines the implication of the energy concentration of the adopted ground acceleration record on the nonlinear response of reinforced concrete structures. The paper employs the wavelet transform to characterize the energy content of the ground acceleration in time and frequency domains.  相似文献   

Assessing the seismic behavior of steel moment frames equipped by elliptical brace through incremental dynamic analysis (IDA)     

Habib Ghasemi Jouneghani  Abbas Haghollahi 《地震工程与工程振动(英文版)》2020,19(2):435-449

Incremental dynamic analysis and nonlinear static pushover analysis are carried out on a performance-based design to determine the seismic demands and capacities of an elliptic braced moment resisting frame (ELBRF). The objective is to assess ductility, overstrength and response modification factors in a modern steel-braced structural system based on incremental dynamic analysis. This integrated system is connected to a beam and column with an appropriate length while providing enough architectural space to allow for an opening without having the common problems associated with architectural spaces in braced systems. Several different classes of buildings are considered on soil type II. Linear dynamic analysis, nonlinear static pushover analysis and incremental nonlinear dynamic analysis related to 12 records from past earthquakes are carried out using OpenSees software. The factors of ductility, overstrength and response modification are calculated for this system. The values of 9.5 and 6.5 are found and suggested only for the response modification factor for ELBRF systems in allowable stress and ultimate limit state methods, respectively. The fragility curves are plotted for the first time for this type of bracing, which contributes to the assessment of building seismic damage.  相似文献   

Bacteria Elimination and SO2 Filtration Using Spacer Fabric Loaded With Natural Zeolite‐Nanosilver Composites          下载免费PDF全文

Mohammad Mehdi Shirmohammadi‐Bahadoran  Majid Montazer  Mehdi Kamali Dolatabadi  Abbas Bahador 《洁净——土壤、空气、水》2018,46(9)

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Integration of cadastral survey data into building information models     

Behnam Atazadeh  Leila Halalkhor Mirkalaei  Hamed Olfat  Abbas Rajabifard  Davood Shojaei 《地球空间信息科学学报》2021,24(3):387-402

Cadastral surveying plays an important role in defining legal boundaries of land and property. The current practice for recording cadastral survey data mainly relies on 2D digital or analog documents. This practice is efficient for simple land parcels but can be challenged in complex building developments. To address the issues stemmed from 2D methods of representing cadastral survey data, 3D spatial information models can be considered as a viable solution for managing cadastral survey data. Building Information Modeling (BIM) enables colsslaborative 3D management of the design, construction, and operation of buildings. There have been extensive studies conducted to investigate the connectivity between BIM and 3D cadaster. Most of these studies focus on managing legal information, such as ownership boundaries and attributes, in BIM-based environments. However, there is limited investigation on how survey- ing measurements can be mapped into BIM. In this study, the proposed method for integrating the cadastral survey data into the BIM environment includes identifying cadastral survey requirements, using BIM entities relevant to cadastral survey data, enrichment of a BIM proto- type, and evaluation of the prototype. The major contribution of this study is to demonstrate the storage of cadastral survey data such as survey marks and traverse lines in the BIM environment. Therefore, this research contributes to the further enrichment of BIM with incorporating data elements related to cadastral surveying practices. It is confirmed that current BIM-based tools provide restricted capabilities for explicit management and visualiza- tion of cadastral survey data. This limitation can be addressed in the future enhancements of BIM in terms of supporting important elements for cadastral survey data.  相似文献   

Stellar dynamics in razor-thin discs with massive nuclear black holes     

Mir Abbas Jalali 《Monthly notices of the Royal Astronomical Society》1999,310(1):97-104

The bifurcations of orbit-averaged dynamics are studied in a class of razor-thin discs with central black holes. The model used here consists of a perturbed harmonic oscillator Hamiltonian augmented with a GM r potential. Through a sequence of conformal and canonical transformations, we reduce the phase-space flows of the system to a set of non-linear differential equations on a sphere. Based on the critical points of the averaged system, we classify orbit families and reveal the existence of six types of periodic motions: circular , long - and short-axis elliptical , long - and short-axis radial and inclined radial orbits. Long-axis elliptical orbits and their surrounding tubes have significant features: whilst they keep stars away from the centre, they elongate in the same direction as the density profile. These properties are helpful in the construction of self-consistent equilibria.  相似文献   

哈纳斯自然保护区地衣生态地理分布的研究   总被引：12，自引：0，他引：12  

努尔巴衣  阿不都拉 《干旱区地理》2000,23(1):72-75

根据 1985年以来实地考察的基础上 ,对保护区自然地理条件和地衣生长发育的地理背景进行了分析 ,对地衣植被的生态地理分布规律进行了初步探讨。并对地衣植被进行了生态分类。  相似文献   

Studying the effects of deformable panels on seismic displacement of gravity quay walls     

Amirali Mostafavi Moghadam  Abbas Ghalandarzadeh  Ikuo Towhata  Majid Moradi  Babak Ebrahimian  Pourya Hajialikhani 《Ocean Engineering》2009,36(15-16):1129-1148

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Enhanced predictions of wave impact pressure by improved incompressible SPH methods     

Abbas Khayyer  Hitoshi Gotoh  Songdong Shao 《Applied Ocean Research》2009,31(2):111-131

A new criterion is proposed for a more efficient assessment of free-surface particles in a particle-based simulation. Enhanced wave impact simulations are carried out by improved Incompressible SPH (ISPH) methods. The first improvement is the same as that in the Corrected ISPH (CISPH; [Khayyer A, Gotoh, H, Shao SD. Corrected incompressible SPH method for accurate water-surface tracking in breaking waves, Coast Eng 2008; 55 (3): 236–250]) method and is proposed for the improvement of momentum conservation. The second improvement is achieved by deriving and employing a higher order source term based on a more accurate differentiation to obtain a less fluctuating and more accurate pressure field. The enhanced performance of improved ISPH methods is demonstrated through the simulation of several fluid impact simulations in comparison with the experimental data and simulation results by other numerical methods.  相似文献   

A new spectral index for the extraction of built-up land features from Landsat 8 satellite imagery     

Rafik Bouhennache  Toufik Bouden  Abdmalik Taleb-Ahmed  Abbas Cheddad 《国际地球制图》2013,28(14):1531-1551

Abstract

Extracting built-up areas from remote sensing data like Landsat 8 satellite is a challenge. We have investigated it by proposing a new index referred as built-up land features extraction index (BLFEI). The BLFEI index takes advantage of its simplicity and good separability between the four major component of urban system, namely built-up, barren, vegetation and water. The histogram overlap method and the spectral discrimination index (SDI) are used to study separability. BLFEI index uses the two bands of infrared shortwaves, the red and green bands of the visible spectrum. OLI imagery of Algiers, Algeria, was used to extract built-up areas through BLFEI and some new previously developed built-up indices used for comparison. The water areas are masked out leading to Otsu’s thresholding algorithm to automatically find the optimal value for extracting built-up land from waterless regions. BLFEI, the new index improved the separability by 25% and the accuracy by 5%.  相似文献   

Field Treatment of MTBE‐Contaminated Groundwater Using Ozone/UV Oxidation   总被引：1，自引：0，他引：1  

Craig L. Patterson  Fernando Cadena  Rajib Sinha  Dzung Kim Ngo‐Kidd  Abbas Ghassemi  E. Radha Krishnan 《Ground Water Monitoring & Remediation》2013,33(2):44-52

Methyl‐tertiary butyl ether (MTBE) is often found in groundwater as a result of gasoline spills and leaking underground storage tanks. An extrapolation of occurrence data in 2008 estimated at least one detection of MTBE in approximately 165 small and large public water systems serving 896,000 people nationally (United States Environmental Protection Agency [U.S. EPA] 2008). The objective of this collaborative field study was to evaluate a small groundwater treatment system to determine the effectiveness of ultraviolet (UV)/ozone treatment in removing MTBE from contaminated drinking water wells. A pilot‐scale advanced oxidation process (AOP) system was tested to evaluate the oxidation efficiency of MTBE and intermediates under field conditions. This system used ozone as an oxidizer in the presence of UV light at hydraulic retention times varying from 1 to 3 min. MTBE removal efficiencies approaching 97% were possible with this system, even with low retention times. The intermediate t‐butyl alcohol (TBA) was removed to a lesser extent (71%) under the same test conditions. The main intermediate formed in the oxidation process of the contaminated groundwater in these studies was acetone. The concentrations of the other anticipated intermediates t‐butyl formate (TBF), isopropyl alcohol (IPA), methyl acetate (MAc), and possible co‐occurring aromatics (BTEX) in the effluent were negligible.  相似文献