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匹配条件: “ Abedin Gagani” ,找到相关结果约103条。
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Micromechanical modeling of anisotropic water diffusion in glass fiber epoxy reinforced composites
Abedin Gagani,Anastasia H Muliana,Andreas T Echtermeyer,Yiming Fan
- , 2018, DOI: 10.1177/0021998317744649
Abstract: Fluid diffusion in fiber reinforced composites is typically anisotropic. Diffusivity in the fiber direction is faster than in the transverse direction. The reason for this behavior is not yet fully understood. In this work, dealing with glass fiber epoxy composite immersed in distilled water, an experimental procedure for determination of anisotropic diffusion constants from a laminate is presented. The method has the advantage that it does not require sealing of the samples edges because 3-D anisotropic diffusion theory is implemented for obtaining the diffusion constants. A microscale model is presented, where matrix and fiber bundles are modeled separately. The matrix properties have been obtained experimentally and the fiber bundle properties have been deduced by the composite homogenized diffusivity model. The analysis indicates that the anisotropic diffusion of the composite is due to inherent anisotropic properties of the fiber bundles
Prediction of Orthotropic Hygroscopic Swelling of Fiber-Reinforced Composites from Isotropic Swelling of Matrix Polymer
Abedin I. Gagani,Andreas T. Echtermeyer,Andrey E. Krauklis
- , 2019, DOI: https://doi.org/10.3390/jcs3010010
Abstract: Abstract Swelling in fiber-reinforced composites is anisotropic. In this work, dealing with glass fiber epoxy composite immersed in distilled water, swelling coefficients are obtained in each direction experimentally. Swelling behaviour in the fiber direction was constrained by the non-swelling fibers and was close to null, while swelling in the transverse directions was found to occur freely—similar to the unconstrained polymer. An analytical method for predicting anisotropic swelling in composites from the swelling of the matrix polymer is reported in this work. The method has an advantage that it is simple to use in practice and requires only a swelling coefficient of the matrix polymer, elastic constants of the matrix and fibers, and a known fiber volume fraction of the composite. The method was validated using finite element analysis. Good agreement was obtained and is reported between experimental hygroscopic swelling data, analytical and numerical results for composite laminates, indicating the validity of this predictive approach. View Full-Tex
A Review of the Fatigue Strength of Load Carrying Shear Welded Joints
Filippo Berto, Abedin Gagani, Relly Victoria V. Petrescu, Florian Ion T. Petrescu
American Journal of Engineering and Applied Sciences , 2017, DOI: 10.3844/ajeassp.2017.1.12
Abstract: In the study it is shown an overview of the latest results of two types of joints of the load carrying welded shear. Tests of fatigue have been carried out on the two solutions specific design features proposed and with the aim of improving the resistance of the joints under cycling loading. By hiring the 3D models, was determined Strain Energy Density (SED), in a volume of control which surrounds the lowest point of interest. All of the experimental results have been presented in short. The synthesis shows that all data are within the range of the scattering of the proposed previously in the specialized literature for steel construction welded.
Finite Element Analysis, 3d Model, Lap Joint, Notc h Stress Intensity Factors
Filippo Berto, Abedin Gagani, Raffaella Aversa, Relly Victoria V. Petrescu, Antonio Apicella and Florian Ion T. Petrescu
American Journal of Engineering and Applied Sciences , 2016, DOI: 10.3844/ajeassp.2016.1269.1291
Abstract: Fatigue is a process (succession of mechanisms) which under the action of time-varying strains or deformations modifies the local properties of a material. These can lead to the formation of cracks and eventual rupture of the structure. Fatigue is in particular characterized by an extent of variation in stress which may be well below the yield strength of the material. The main stages of fatigue failure of an assembly are the initiation of cracks (if defects are not already present in the material), the propagation of cracks and the final rupture. The parameters often used to predict the fatigue behavior and thus the number of cycles at break of a structure is: The amplitude of the stress (loading or imposed strain), its average value, the surface state and the medium In which the structure will be used. Even if the study of fatigue is based on theoretical considerations (in particular the mechanics of the rupture), it is essentially an experimental field. The characterization of a material, a part, an assembly, a structure, requires numerous tests and measurements. The work deals with multiaxial fatigue power of specimens which are notched and all made of 40CrMoV13.9. Circumferentially V-notched specimens and semicircular notched were tested under combined tension and torsion loading, both, in phase or out of phase. Geometry of symmetric axis of V notched issues has been characterized of a notch radius constant from (1 mm) and V-notch opening angle of 90°. The semicircular specimens were characterized by a constant notch tip radius. For both situations the net diameter sectional area was 12 mm. The results from multi-axial tests are discussed together with those obtained being all under loading pure torsion and tension by the issues notched having the same geometry. Altogether more than 120 new fatigue data are summarized in the present work. All presented fatigue data are first in terms of nominal amplitudes stress and then reanalyzed in terms of the mean value of the strain energy density evaluated over a finite size semicircular sector surrounding the tip of the notch.
Management and Reduction of Chemical Nitrogen Consumption in Agriculture  [PDF]
Abedin Zafari, Mohammad Hossein Kianmehr
American Journal of Plant Sciences (AJPS) , 2012, DOI: 10.4236/ajps.2012.312A224
Abstract:

Nitrogen is an effective material for improving the crop production. There is a big concern about rising chemical nitrogen usage as fertilizer in soil, because some forms of nitrogen absorbs in soil and causes an increase of environment and water pollution and decrease fertilizer efficiency. Composted cow manure is an important resource of organic nitrogen which improves the soil conditions. However, low density of composted cow manure and inconstant nutrient content are two factors that limit the application of composted cow manure. The densification technology is an effective solution for both problems. In this research first the capability of single screw extruder for production of fertilizer pellets including composted cow manure and nitrogen fertilizer was studied and then the effect of fertilizer pellet on the reduction of chemical nitrogen consumption was evaluated. The response of basil plants was determined in three treatments: T1 control (no fertilizer), T2 (nitrogen fertilizer) and T3 (pellet). The results showed that pelletization can be used as a proper method for slow-release nitrogen fertilizer; enhance nitrogen uptake and reducing the chemical nitrogen consumption. The results also showed that all basil responses (chlorophyll content, total weight, leaves weight, root weight and leaf area) were significantly affected by application of N fertilizer and pellet. While maximum recorded parameters were observed with application pellet.

Web 2.0 and Online Learning and Teaching: A Preliminary Benchmarking Study
Babak Abedin
Asian Social Science , 2011, DOI: 10.5539/ass.v7n11p5
Abstract: The context of online learning has been transformed by the advent of Web 2.0. While universities have just recently started to use Web 2.0 applications, these applications already exist in the students’ personal and educational world. Yet it is still not clear in what ways universities may be able to incorporate Web 2.0 applications in learning and teaching practices. This paper gives an overview of Web 2.0 applications for universities and discusses new opportunities that Web 2.0 has brought for universities. Examples of how some universities have used these applications are then outlined and categorized. The paper also discusses some of the main issues with Web 2.0 applications and provides recommendations for resolving these issues.
Identification of Fertility Enhancing and Inhibiting Factors: A Study on Married Adolescents in Bangladesh
Sumaiya Abedin
Asian Social Science , 2011, DOI: 10.5539/ass.v7n5p191
Abstract: Fertility is associated with complex biological process of women life through the transition of pregnancy and birth. Some socio-demographic variables are hypothesized to affect the level of fertility, many of those factors enhance fertility where as some other inhibit the fertility. Our aim in this study is to reveal the most influential fertility inhibiting and enhancing factors for married adolescents. The intuition behind this is to explore the interaction of both enhancing and inhibiting factors on the level of adolescent fertility. In this sequel, a hypothesized framework based on proximate covariates is used to describe the theoretical relationship among the covariates and factor analysis is applied to identify the dominant fertility enhancing and inhibiting factors. Among all proximate covariates highest level of education is speculated as the most influential fertility inhibiting factor for adolescents.
Operationalizing Off-task Sociability of Asynchronous Computer Supported Collaborative Learning
Babak Abedin,Farhad Daneshgar
Communications of the IBIMA , 2008,
Abstract: Many previous studies have emphasized the role of the sociability of the computer supported collaborative learning (CSCL) environments on learning achievements. Also, recent studies have reported that other than on-task interaction, students have considerable off-task interactions in CSCL environments. Yet, more studies are needed to clarify the off-task aspect of social interactions in CSCL and sociability of the environment. This paper attempts to investigate and operationalize sociability of CSCL environments from off-task point of view in order to further clarify this aspect of CSCL. It first reviews previous sociability questionnaires and instruments and then proposes a list of measure to represent and operationalize off-task sociability of CSCL. The proposed list of measures is then validated through experts’ judges and finally implications are discussed.
A Review of Alcohol-Related Harms: A Recent Update
Abedin Iranpour,Nouzar Nakhaee
- , 2019, DOI: 10.22122/ahj.v11i2.225
Abstract: In the early decades of the 20th century, discussions regarding alcohol were dominantly directed toward its therapeutic uses, but authorities now state that any level of alcohol consumption poses negative effects on health. Over recent months, increased attention has been devoted to disease burdens attributable to alcohol use worldwide. As more and more studies are conducted to illuminate the harmful effects of alcohol on different body systems, the mounting evidence generated requires documentation and publication. The current review was aimed at providing an overview of the recent literature on the adverse consequences of alcohol consumption
Effect of Borage Powder on Blood Cells and Immune System
Abedin Heidarizadi 1
- , 2014,
Abstract: This study was conducted to compare the effects of diets Borage Powder and control (no additives diets) on broiler’s average blood cell counts and immune system on the broiler chicks. Sixty four male broiler chicks (Ross 308) randomly allocated into one of two treatments with four replicates of eight chickens based on a completely randomized block design.? Diets were include control (no additives diets) and BP1 (5 g/kg Borage Powder) BP2 (7.5 g/kg Borage Powder). Results have been shown that number of Wight blood cell (WBC) affected by BP1 and BP2 diets as those increase number of WBC. These results showed that addition of borage powder to the broiler diet improved Immune System.??
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