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排序方式: 共有177条查询结果,搜索用时 826 毫秒
11.
Behrouz BEHNAM Fahimeh SHOJAEI Hamid Reza RONAGH 《Frontiers of Structural and Civil Engineering》2019,13(4):904
Investigating progressive collapse of tall structures under beam removal scenarios after earthquake is a complex subject because the earthquake damage acts as an initial condition for the subsequent scenario. An investigation is performed here on a 10 story steel moment resisting structure designed to meet the life safety level of performance when different beam removal scenarios after earthquake are considered. To this end, the structure is first subjected to the design earthquake simulated by Tabas earthquake acceleration. The beam removal scenarios are then considered at different locations assuming that both ends connections of the beam to columns are simultaneously detached from the columns; thus the removed beam falls on the underneath floor with an impact. This imposes considerable loads to the structure leading to a progressive collapse in all the scenarios considered. The results also show that the upper stories are much more vulnerable under such scenarios than the lower stories. Hence, more attention shall be paid to the beam-to-column connections of the upper stories during the process of design and construction. 相似文献
12.
Amir Movafeghi Yahaghi Effat Rokrok Behrouz Mirzapour Mahdi 《Russian Journal of Nondestructive Testing》2020,56(4):361-368
Russian Journal of Nondestructive Testing - The location of reinforcement bar in concrete, the bar corrosion, diameter and the depth below the surface are important factors in the evaluation of the... 相似文献
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Mohammad Taghan Sasanpour Taheri Ali Movafeghi Amir Rokrok Behrouz 《Russian Journal of Nondestructive Testing》2019,55(12):967-974
Russian Journal of Nondestructive Testing - The purpose of this article is to determine the mathematical function of the optical behavior of radiographic films/images produced by gamma-ray... 相似文献
15.
Maysam Abbasi Ehsan Abbasi Behrouz Tousi Gevork B. Gharehpetian 《International Journal of Circuit Theory and Applications》2019,47(10):1630-1644
This paper presents a new step-up switched-capacitor (SC) DC-DC converter which has many advantages such as reduction in investment cost, control complexity, number of components, voltage stress on components, and size over traditional topologies. In the proposed structure, power switches are reduced in number which in turn leads to the merits mentioned earlier and makes the converter more suitable for industrial applications. Furthermore, a previously introduced zero-current switching (ZCS) method is used here which provides soft switching for the devices. There is also a reduction in the number of required inductors to achieve ZCS due to the decreased number of switches in the proposed converter. The proposed converter is validated by comprehensive simulation results in MATLAB Simulink environment and also precise experimental results which show the acceptable performance of the proposed topology. 相似文献
16.
Maryam Safarbeiranvnd Hakimeh Amanipoor Sedigheh Battaleb-Looie Kamal Ghanemi Behrouz Ebrahimi 《Water Resources Management》2018,32(11):3611-3628
In this research, based on the qualitative data of 40 wells, variations of water quality parameters of the Central Plain Aquifer were evaluated using kriging and IDW (Inverse Distance Weighting) methods. Owing to the normal distribution of the studied parameters (except Na+, SO42?, and TH: total hardness), ordinary kriging was used for modeling. The analysis of the data trends indicated that all the variables were influenced by in two general trends, i.e., NW–SE and NE–SW. In fact, these trends were a result of the effect of the structural conditions on aquifer properties such as transmissivity and flow direction. Variogram analysis (based on C0 near zero and C0/σ2 ratio between 0.0–0.5) showed that the Na+, TDS (total dissolved solids), Ca2+, and TH variables have a good spatial structure and the BOD (biochemical oxygen demand), COD (chemical oxygen demand), NO3?, and EC variables have poor spatial structure. The BOD, COD, NO3?, and EC (electrical conductivity) variables have the smallest range and isotropic distribution. On the other hand, the Ca2+, Mg2+, Na+, SO42?, Cl?, HCO3?, pH, TDS, TH and Alk (alkalinity) parameters are characterized by anisotropic distributions. The Na+, TDS, Ca2+, and TH variables have the largest range. The results showed that both the IDW and kriging methods have close estimates to one another. The pH variable decreases toward the outlet whereas the EC and TDS variables increase along the direction of water flow and toward the outlet. The distributions of the BOD and COD variables do not perfectly match with the aggregation of industrial activities in the central part as well as the agricultural activities in the southeastern and central parts of the aquifer. The distributions of the Ca2+, Mg2+, and Alk variables completely follow the geology condition and regional spread of carbonate formations. The Na+ concentration increases from the center toward the outlet. The concentration of the Cl? variable is the highest in the central part of the plain due to the concentration of agricultural and industrial activities. The distribution of the SO42? variable is influenced by a natural factor (lithology), especially in the southeastern parts and the outlet as well as artificial factors (agricultural and industrial activities) in the central and southeastern parts of the aquifer. The NO3? variable, which is directly influenced by agricultural and livestock-farming activities, has its maximum concentration in the southeastern areas. 相似文献
17.
This study investigates the forced vibration of functionally graded hexagonal
nano-size plates for the first time. A quasi-three-dimensional (3D) plate theory including
stretching effect is used to model the anisotropic plate as a continuum one where smallscale effects are considered based on nonlocal strain gradient theory. Also, the plate is
assumed on a Pasternak foundation in which normal and transverse shear loads are taken
into account. The governing equations of motion are obtained via the Hamiltonian
principles which are solved using analytical based methods by means of Navier’s
approximation. The influences of the exponential factor, nonlocal parameter, strain gradient
parameter, Pasternak foundation coefficients, length-to-thickness, and length-to-width
ratios on the dynamic response of the nanoplates are examined. In addition, the accuracy of
an isotropic approximate instead of the anisotropic model is studied. The dynamic behavior
of the system shows that mechanical mathematics-based models may get better results
considering the anisotropic model because the dynamic response can cause prominent
differences (up to 17%) between isotropic approximation and anisotropic model. 相似文献
18.
Jannesari Mohammad Mosaddegh Peiman Kadkhodaei Mahmoud Kasprzak Henryk Jabbarvand Behrouz Mahmoud 《Mechanics of Time-Dependent Materials》2019,23(3):373-384
Mechanics of Time-Dependent Materials - Non-contact tonometers, including ORA and Corvis ST, are not only used to estimate intraocular pressure (IOP) in clinical surveys but are also utilized to... 相似文献
19.
Effat Yahaghi Mahdi Mirzapour Amir Movafeghi Parisa Mohammadi Matin Behrouz Rokrok 《Research in Nondestructive Evaluation》2019,30(2):80-88
Testing and detecting potential defects in works of art is usually required to cause minimal or no damage; industrial Radiography Testing (RT) is often the method of choice provided the images are of the required high quality and yield high defect detection sensitivity. Various digital image processing methods can be employed to achieve improved image quality and information extraction as required. The level and nature of the noise in the RT images is usually unknown. In addition to the different noises, the image quality is degraded by the blurring effect. In this study, a modified form of the Fast Iterative Shrinkage-Thresholding Algorithm (FISTA) with quadratic regularization strategy was developed and applied to remove the blurring. The output of the application of the method to number RT images of five art objects was evaluated by industrial radiography and antiquities experts. It was confirmed that the applied method was efficient and improved image quality and defect detection. 相似文献
20.