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571.
Akbar Pirmoz Amir Saedi Daryan Hajar Ebrahim Darbandi 《Journal of Constructional Steel Research》2008,64(4):436-446
In this paper, the effect of web angle dimensions on moment-rotation behavior of bolted top and seat angle connections, with double web angles is studied. Several 3D parametric finite element (FE) models are presented in this study whose geometrical and mechanical properties are used as parameters. In these models, all of the connection components, such as beam, column, angles and bolts are modeled using solid elements. The effect of interactions between components, such as slippage of bolts and frictional forces, are modeled using a surface contact algorithm. To evaluate the behavior of connection more precisely, bolt pretensioning force is applied on bolt shanks as the first load case. The results of this numerical modeling are compared with the results of experimental works done by other researchers and good agreement was observed. To study the influence of shear force on behavior of these connections, several models were analyzed using different values of shear force. The effect of important parameters, especially the effect of web angle dimension, is studied then. An equation is proposed to determine the reduction factor for initial rotational stiffness of connection using connection initial rotational stiffness, yield moment, the expected shear force and web angle dimension. The proposed equation is compared with other existing formulations and it was observed that the proposed model is a better estimator of connection behavior. 相似文献
572.
Najafi E Cruz DH Obst M Hitchcock AP Douhard B Pireaux JJ Felten A 《Small (Weinheim an der Bergstrasse, Germany)》2008,4(12):2279-2285
The polarization dependence (linear dichroism) of the C 1s X-ray absorption spectrum of individual multi-walled carbon nanotubes (MWCNTs) is measured using scanning transmission X-ray microscopy. A very strong dichroic effect is found in the C 1s --> pi* transition, with almost complete disappearance of this transition when the electric-field (E)-vector is aligned parallel to high-quality (low-defect) MWCNTs and maximum intensity when the E-vector is orthogonal to the tube axis. In contrast, there is very little dichroism in the C 1s --> sigma* transitions. The origin of this polarization effect is explained. The magnitude of the polarization dependence is found to differ in MWCNTs synthesized by different methods (arc discharge versus chemical vapor deposition). This is ascribed to differences in densities of sp(2)-type defects. The potential for use of this signal to characterize defects in single-carbon-nanotube devices is discussed. 相似文献
573.
Karin Thurner Ebrahim Razzazi-Fazeli Karl-Heinz Wagner Ibrahim Elmadfa Wolfgang Luf 《European Food Research and Technology》2007,224(6):797-800
The effect of pan-frying on the formation of cholesterol oxidation products (COPs) in different processed meat samples (beef
patties, braised meat, and fillets of pork) was studied. Samples were pan-fried with or without addition of oil. Different
unsaturated oils (olive oil, corn oil or partly hydrogenated plant oil) were used throughout the study. After extraction,
seven toxicologically relevant COPs were analyzed using LC–MS. Prior to heat processing up to 6.7 mg COPs/kg extracted fat
could be detected in the raw material. Neither the cholestanetriol nor 25-hydroxycholesterol, which are the most cytotoxic
COPs in vitro, were detectable in any sample. Differences in the COPs contents were observed between beef (up to 16.5 mg/kg
extracted fat) and pork (up to 22.2 mg/kg extracted fat) samples. In prepared samples higher COPs content was noted compared
with raw samples. Generally, a certain order of COPs increase dependent on the plant oil used could be recognized: corn oil
< partially hydrogenated plant oil < olive oil. It appears that short heating time, mild heating conditions, and the use of
fresh and shortly stored raw materials keep COPs levels low. 相似文献
574.
575.
Unsteady cavitation causes noise,damage,and performance decline in the marine engineering and fluid machinery systems.Therefore,finding a method to control the ... 相似文献
576.
Mostaanzadeh Hossein Shahmohammadi Mohammad Ehsani Ali Moharramnejad Mojtaba Honarmand Ebrahim 《Journal of Materials Science: Materials in Electronics》2021,32(22):26539-26547
Journal of Materials Science: Materials in Electronics - In the present study, we introduce a simple chemical method to synthesize Zn-based MOF (Zn-BTC). The structural morphology and... 相似文献
577.
In this study, buckling of rectangular orthotropic plates resting on a Pasternak elastic foundation under biaxial in-plane loading by the power series method (the method of Frobenius) was analyzed. Similar to many studies, two opposite edges of loading are simply supported and two other edges are assumed clamped. In order to extract the characteristic equations of orthotropic rectangular plate under in-plane loading resting on a Pasternak elastic foundation, the classical plate theory, by considering the interaction between plate and foundation, is used. The results showed that in the aspect ratio of less than 2, the existing Pasternak foundation caused the buckling load to increase severely, but by increasing the aspect ratio, the effect of the foundation is negligible. Applying the in-plane load in the y-direction caused the buckling load to decrease, but by increasing the aspect ratios the effect of the load is negligible. 相似文献
578.
Nesrine Ebrahim Hajir A. Al Saihati Ola Mostafa Amira Hassouna Sameh Abdulsamea Eman Abd El Aziz M. El Gebaly Nashwa Hassan Abo-Rayah Dina Sabry Mohamed El-Sherbiny Abdelmonem G. Madboly Noha Ibrahim Hussien Raja El Hasnaoui Saadani Hasnaa Ali Ebrahim Omnia A. M. Badr Nehal M. Elsherbiny Rabab F. Salim 《International journal of molecular sciences》2022,23(11)
579.
Rushikesh Battulwar Masoud Zare-Naghadehi Ebrahim Emami Javad Sattarvand 《岩石力学与岩土工程学报(英文版)》2021,13(4):920-936
In the last two decades, significant research has been conducted in the field of automated extraction of rock mass discontinuity characteristics from three-dimensional (3D) models. This provides several methodologies for acquiring discontinuity measurements from 3D models, such as point clouds generated using laser scanning or photogrammetry. However, even with numerous automated and semi-automated methods presented in the literature, there is not one single method that can automatically characterize discontinuities accurately in a minimum of time. In this paper, we critically review all the existing methods proposed in the literature for the extraction of discontinuity characteristics such as joint sets and orientations, persistence, joint spacing, roughness and block size using point clouds, digital elevation maps, or meshes. As a result of this review, we identify the strengths and drawbacks of each method used for extracting those characteristics. We found that the approaches based on voxels and region growing are superior in extracting joint planes from 3D point clouds. Normal tensor voting with trace growth algorithm is a robust method for measuring joint trace length from 3D meshes. Spacing is estimated by calculating the perpendicular distance between joint planes. Several independent roughness indices are presented to quantify roughness from 3D surface models, but there is a need to incorporate these indices into automated methodologies. There is a lack of efficient algorithms for direct computation of block size from 3D rock mass surface models. 相似文献
580.
Anjana Soorajkumar Ebrahim Alakraf Mohammed Uddin Stefan S. Du Plessis Alawi Alsheikh-Ali Richard K. Kandasamy 《International journal of molecular sciences》2022,23(15)
Short linear motifs (SLiMs) are short linear sequences that can mediate protein–protein interaction. Mimicking eukaryotic SLiMs to compete with extra- or intracellular binding partners, or to sequester host proteins is the crucial strategy of viruses to pervert the host system. Evolved proteins in viruses facilitate minimal protein–protein interactions that significantly affect intracellular signaling networks. Unfortunately, very little information about SARS-CoV-2 SLiMs is known, especially across SARS-CoV-2 variants. Through the ELM database-based sequence analysis of spike proteins from all the major SARS-CoV-2 variants, we identified four overriding SLiMs in the SARS-CoV-2 Omicron variant, namely, LIG_TRFH_1, LIG_REV1ctd_RIR_1, LIG_CaM_NSCaTE_8, and MOD_LATS_1. These SLiMs are highly likely to interfere with various immune functions, interact with host intracellular proteins, regulate cellular pathways, and lubricate viral infection and transmission. These cellular interactions possibly serve as potential therapeutic targets for these variants, and this approach can be further exploited to combat emerging SARS-CoV-2 variants. 相似文献