http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
- 中文 을 입력하시려면 zhongwen을 입력하시고 space를누르시면됩니다.
- 北京 을 입력하시려면 beijing을 입력하시고 space를 누르시면 됩니다.
RISS 인기검색어
- 검색키워드
- 저자 : Masoud Tahani (검색결과 5 건)
- 무료
- 기관 내 무료
- 유료
-
Amin Anjomshoa,Masoud Tahani 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.6
In the present study a continuum model based on the nonlocal elasticity theory is developed for free vibration analysis of embedded orthotropic thick circular and elliptical nano-plates rested on an elastic foundation. The elastic foundation is considered to behave like a Pasternak type of foundations. Governing equations for vibrating nano-plate are derived according to the Mindlin plate theory in which the effects of shear deformations of nano-plate are also included. The Galerkin method is then employed to obtain the size dependent natural frequencies of nano-plate. The solution procedure considers the entire nano-plate as a single super-continuum element. Effect of nonlocal parameter, lengths of nano-plate, aspect ratio, mode number, material properties, thickness and foundation on circular frequencies are investigated. It is seen that the nonlocal frequencies of the nano-plate are smaller in comparison to those from the classical theory and this is more pronounced for small lengths and higher vibration modes. It is also found that as the aspect ratio increases or the nanoplate becomes more elliptical, the small scale effect on natural frequencies increases. Further, it is observed that the elastic foundation decreases the influence of nonlocal parameter on the results. Since the effect of shear deformations plays an important role in vibration analysis and design of nano-plates, by predicting smaller values for fundamental frequencies, the study of these nano-structures using thick plate theories such as Mindlin plate theory is essential.
-
Ali Mohammad Naserian Nik,Masoud Tahani 대한기계학회 2009 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.23 No.8
The intent of the present study is to employ the extended Kantorovich method for semi-analytical solutions of laminated composite plates with arbitrary lamination and boundary conditions subjected to transverse loads. The method based on separation of spatial variables of displacement field components. Within the displacement field of a first-order shear deformation theory, a laminated plate theory is developed. Using the principle of minimum total potential energy, two systems of coupled ordinary differential equations with constant coefficients are obtained. The equations are solved analytically by using the state-space approach. The results obtained are compared with the Levy-type solutions of cross-ply and antisymmetric angle-ply laminates with various admissible boundary conditions to verify the validity and accuracy of the present theory. Also, for other laminations and boundary conditions that there exist no Levy-type solutions the present results are compared with those obtained by other investigators and finite element method. It is found that the present results have very good agreements with those obtained by other methods.
-
Amir R. Askari,Masoud Tahani 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.5
This paper presents an analytical and size-dependent model for vibrational analysis of fully clamped rectangular microplates. Modifiedcouple stress theory (MCST) and the Kirchhoff plate model are considered, and Hamilton’s principle is employed to derive the sizedependentequation of motion that accounts for the effect of residual stresses. The natural frequencies of the microplate are extractedanalytically by extended Kantorovich method. The present findings are validated with the available results in the literature, and an excellentagreement is observed between them. In addition, a parametric study is conducted to demonstrate the significant effects of couplestress components on the natural frequencies of fully clamped microplates. The ratio of MCST natural frequencies to those obtained withclassical theory depends only on the Poisson’s ratio of the plate and is independent of the aspect ratio of the plate for cases with no residualstresses.
-
Momeni-Khabisi, Hamed,Tahani, Masoud Techno-Press 2022 Advances in nano research Vol.12 No.4
In the present study, the nonlocal strain gradient theory is used to predict the size-dependent buckling and post-buckling behavior of geometrically imperfect nano-scale piezo-flexomagnetic plate strips in two modes of direct and converse flexomagnetic effects. The first-order shear deformation plate theory is used to analyze analytically nano-strips with simply supported boundary conditions. The nonlinear governing equations of equilibrium and associated boundary conditions are derived using the principle of minimum total potential energy with consideration of the von Kármán-type of geometric nonlinearity. A closed-form solution of governing differential equation is obtained, which is easily usable for engineers and designers. To validate the presented formulations, whenever possible, a comparison with the results found in the open literature is reported for buckling loads. A parametric study is presented to examine the effect of scaling parameters, plate slenderness ratio, temperature, the mid-plane initial rise, flexomagnetic coefficient, different temperature distributions, and magnetic potential, in case of the converse flexomagnetic effect, on buckling and post-buckling loads in detail.
-
Investigation of the Factors Affecting Bone Mineral Density in Children with Celiac Disease
Seyed Mohsen Dehghani,Homa Ilkhanipour,Leila Samipour,Ramin Niknam,Iraj Shahramian,Fateme Parooie,Morteza Salarzaei,Masoud Tahani 대한소아소화기영양학회 2022 Pediatric gastroenterology, hepatology & nutrition Vol.25 No.2
Purpose: Children with celiac disease (CD) are at an increased risk of low bone mineral density (BMD) owing to malabsorption of fat-soluble vitamins, inflammation, and malnutrition. This study aimed to determine the prevalence and risk factors for low BMD in Iranian children with CD. Methods: This prospective cohort study examined 149 Iranian children with CD between 2011 and 2018 at Zabol University of Medical Sciences. BMD was measured using dual-energy X-ray absorptiometry. Demographic, clinical, and laboratory data were collected from patients’ medical records. Logistic regression analysis was performed to identify the factors associated with low areal BMD (BMD-Z <−2) in the lumbar spine and femoral neck. Descriptive data were analyzed using the mean, standard deviation, and relative frequency. Data were analyzed using the chi-square test, t-test, and analysis of variance. Results: Of the 149 children with CD, 27.5% had osteoporosis. The mean body mass index (BMI) Z score was −1.28±1.2. Lower BMI was associated with a higher likelihood of BMD-Z (odds ratio 2.17; p≤0.05). Conclusion: Overall, the findings of this study showed that there was no correlation among Marsh classification, presence of specific human leukocyte antigens, and low BMD in Iranian children with CD. BMI can be a predictor of bone density in children with CD and may be applied clinically in early screenings to evaluate the bone health status in these children.
연관 검색어 추천
이 검색어로 많이 본 자료
활용도 높은 자료
