Search

Geotechnical earthquake engineers have been trying to determine the most appropriate solution techniques for ground response analysis under earthquake loadings. This paper presents the importance of the adequate soil behavior model to simulate earthquake site response analysis. The influence of nonlinearity and linearity of soils on the site response is also investigated. Many methods have been proposed for the analysis of one-dimensional ground response such as nonlinear methods and equivalent linear with reduced modulus. Using 13 well known earthquake records and geotechnical information of sand in the Qeshm Island (Iran) and classification of earthquakes based on seismic parameters, the influence of each parameter on the Response spectra and Fourier Spectrum of surface of ground becomes evident. Analysis was done using two softwares; EERA (equivalent linear analysis) and NERA (nonlinear analysis) and compared. Finally, output of the software is compared with the reference result on site.

In this paper, we delve into frame theory to create an in- novative iterative method for resolving the operator equation Lu = f. In this case, L : H ! H, a bounded, invertible, and self-adjoint lin- ear operator, operates within a separable Hilbert space denoted by H. Our methodology, which is based on the GMRES projective method, in- troduces an alternate search space, which brings another dimension to the problem-solving process. Our investigation continues with the assess- ment of convergence, where we look at the corresponding convergence rate. This rate is intricately in uenced by the frame bounds, shedding light on the eflectiveness of our approach. Furthermore, we investigate the ideal scenario in which the equation finds an exact solution, providing useful insights into the practical implications of our work. [ABSTRACT FROM AUTHOR]

Titanium dioxide nanoparticles (TiO2 NPs) are prepared by using the sol–gel technique at calcination temperatures of 300, 400 and 500 °C. TiO2 NPs prepared at 400 °C are doped with various molar percentages of Ag because of their suitable crystalline and optical properties. Results of UV–Vis adsorption and X-ray diffraction show that the TiO2 NPs' crystalline structure consists of a mixture of anatase and rutile crystalline phases and calcination temperature play a significant effect on TiO2 NPs structural properties. After the Ag doping of TiO2 NPs, peaks corresponding to TiO and Ag compounds and a pure anatase phase appear in the X-Ray spectrum. UV–Vis adsorption results illustrate the down-shifting of TiO2 NPs doped with Ag, enhancing the photo-catalytic efficiency of Ag-TiO2 NPs. XPS results display significant boarding of Ti 2p peaks related to Ag-TiO2 NPs which may be explained by doping of TiO2 NPs by Ag. The antibacterial property of Ag-TiO2 NPs under various radiation conditions illustrates the significant role of Ag-doped in TiO2 NPs to enhance absorption spectra of sunlight and improvement of photo-catalyst activity of Ag-TiO2 NPs to kill Ecoli-bacteria. [ABSTRACT FROM AUTHOR]

In this research, the fabrication of transparent Alumina was done by spark plasma sintering (SPS). Two types of alpha and gamma Alumina powders with particle size of 200 and 50 nm were used, respectively. The sintering assisted materials used in this research were magnesium nitrate and lanthanum nitrate, each of which was used 100 ppm using a chemical precipitation process. Calcination was performed at 800°C and the resulting powders were subjected to SPS at 1500 °C with a rate of 50 °C/min for 15 minutes under a pressure of 70 MPa. The phase composion was analyzed by Xray diffraction (XRD) before and after SPS. The morphology of the powders and the microstructure of the sintered samples were studied using scanning electron microscopy (SEM). The bulk density was obtained to be 3.94 gr/cm3 and 3.9 gr/cm3 in the alpha and gamma samples, respectively. The UV-Visible transmission test showed 20% transmission in the alpha alumina sample. The amount of IR transmission in the alpha and gamma samples was obtained to be 65% and 25%, respectively. The alpha alumina sample had a higher transmission percentage and density compared to the gamma sample. [ABSTRACT FROM AUTHOR]

One of the most problems that affects the performance of the journal bearing is the shaft misalignment. Misalignment may result due to installation error, shaft deformation, manufacturing error, bearing wear, etc. This paper presents a solution for the misaligned journal bearing problem under hydrodynamic regime. The Reynolds equation has been solved numerically for a finite length bearing based on the finite difference method. The solution demonstrates a new model for the representation of the 3D misalignment geometry and also a detailed procedure for the implementation of the boundary condition in the numerical solution is explained. Furthermore, the convergence of the solution to the required load is investigated. The results reveal a severe thinning in the levels of film thickness and significant rising of the maximum pressure value when the misalignment is taken into consideration. [ABSTRACT FROM AUTHOR]

In this research, Germanium-carbon coatings were deposited on ZnS substrates by plasma enhanced chemical vapor deposition (PECVD) using GeH4 and CH4 precursors. Optical parameters of the Ge1-xCx coating such as refractive index, Absorption coefficient, extinction coefficient and band gap were measured by the Swanepoel method based on the transmittance spectrum. The results showed that the refractive index of the Ge1-xCx coatings at the band of 2 to 2.2 μm decreased from 3.767 to 3.715 and the optical gap increased from 0.66 to 0.72 eV as CH4:GeH4 increases from 10:1 to 20:1. [ABSTRACT FROM AUTHOR]

In this paper, using a frame of subspaces we transform an operator equa- tion to an equivalent l2-problem. Then, we propose an adaptive algorithm to solve the problem and investigate the optimality and complexity properties of the algorithm. [ABSTRACT FROM AUTHOR]

Introduction: Vitamin D plays an important role in the regulation of several genes associated with metabolic disorders. This study was designed to investigate the relationship between serum 25 (OH) D and parathyroid hormone (PTH) levels, and insulin resistance in patients with non-alcoholic fatty liver disease (NAFLD). Methods: A case-control study was carried out among patients with NAFLD (n=80) as cases and age-matched subjects without NAFLD (n= 80) as controls. After 8-12 h of fasting, serum 25 (OH) D, insulin and PTH levels were assessed using Enzyme-Linked Immunosorbent Assay (ELISA) technique. Multivariate logistic regression model was applied to assess the relationship between vitamin D and PTH and insulin resistance in the development of NAFLD by adjusting for the confounders (sex, BMI and waist-to-hip ratio). Results: There was no significant difference in sunlight exposure between the two groups (p= 0.274). Patients with NAFLD had significantly lower serum 25(OH) D levels and higher PTH levels compared to subjects without NAFLD (p< 0.001). The association between NAFLD and low 25(OH) vitamin D levels was independent of confounders (adjusted OR: 8.78, CI 95%:1.71, 45.03). Homeostatic Model Assessment Insulin Resistance (HOMA-IR) as insulin resistance index was significantly high in the NAFLD group (adjusted OR: 1.80, CI 95%: 1.32, 2.47). Conclusion: Our findings showed that lower serum 25 (OH) D levels and higher HOMA indices were independently associated with increased odds of NAFLD and there was a direct but not significant relationship between PTH serum levels and the risk of NAFLD. [ABSTRACT FROM AUTHOR]