Sharif Digital Repository

The purpose of this work is to introduce an inverse finite element tool for prediction of the blank geometry and forming severity in stamping of 3D sheet metal parts. To achieve this goal total deformation theory of plasticity has been employed. In this method the final 3D part is unfolded on the flat surface in one step and on predefined surface in multistage analysis. The problem for one step analysis is reduced to two dimensional computations. The effect of curvature of initial blank and the number of stages in forming process are also considered. To investigate the capability of this work, predictions of the blank shape and strain distribution and forming severity have been performed on... 

Always, there has been a great interest toward electromagnetic wave propagation and new ways for simulation of the problem. Level set methods provide a powerful mathematical framework for propagating surfaces (in 3-D) or curves (in 2-D). The contours of the moving objects are viewed as the zero level sets of a function and propagated in a Eulerian point of view by means of a Hamilton–Jacobi partial differential equation expressing the conservation of the level sets under a given velocity field. Level set methods have been applied in a wide range of domains, such as physics, chemistry, fluid dynamics, combustion, image processing… In this thesis, we introduce a new numerical procedure for... 

One of the most common processes in shaping profiles with various cross-sections (with parallel surfaces), is a direct extrusion process. Always in the process, minimize the extrusion pressure and reduce the output profile curvature form of the main goals of researchers. Minimize the extrusion pressure in the mold design using nonlinear, many relationships are presented. Also, to reduce the output profile curvature of the mold, extrusion molding is used mostly at the outlet of the bearing. The purpose of this research is suitable for bearing design eliminates the curvature of the final product is extrusion. In this study interior design templates and profiles bearing acts simultaneously on... 

The the nervous system as a most comlicated body system , plays an important and vital role for the body systems. damage to the peripheral nervous system result in nervous system disorders which claissified to Neuropraxia, Axonotmesis and Neurotmesis based on damage itensity. tissue engineering considered as one of the repairing nervous damage way, which by creating 3D substrat (scaffold) with proper physical structure, increses possibility of adhesion, growth and proliferation of cells to increase regeneration rate of damaged nerve. in this study, a combination of dual-electrospinning and rolling the spun film used to preparate a nerve guidance conduit (NGC) based on gelatin, PCL and... 

In recent years, water issues have been the focus of increasing international concern and debate. Agriculture is not only the world's largest water user in terms of volume, it is also a relatively low-value, low-efficiency water user. These facts are forcing governments and donors to rethink the economic, social and environmental implications of irrigation projects. Population growth, increase in water demand, the extended drought and utilization of too much water for agricultural, have been made water conflicts over water resources. Due to the drought has a significant economic and social impact on the irrigated agricultural sector, Water markets based on transferable water rights developed... 

The use of polyether ether ketone (PEEK) in bone implants is limited due to a lack of cell adhesion and proliferation. Therefore, in this study, we modified the surface of PEEK with a nanocomposite coating containing piezoelectric and bioactive properties. Sulfonated PEEK with suitable mechanical and hydrophilic properties along with polyvinylidene fluoride was used as a biocompatible polymer with piezoelectric properties for coating. Also, nanohydroxyapatite was used as a bioactive material, and carbon nanofibers with significant mechanical and electrical properties were used in the nanocomposite. The surface was sulfonated as an intermediate layer to improve the connection between the... 

Fabrication and In-Vitro Evaluation of Anti-Cancer Hydrogel Containing Combination of Magnesium Oxide Nanoparticle Anticancer Drug for use in Breast Cancer Treatments  

In the present work, the experiments were carried out for two types of PAM (3330 and 3630) with three distinct concentrations (25, 40 and 55 ppm) and TiO_2-water nanofluid for four concentrations (1.5, 2, 2.5 and 3 vol. %), and the Nusselt number and friction factor for each of them expressed separately. The Reynolds number was in the range from 11000 to 21000. The steady state turbulent convective heat transfer and friction factor of the combination of TiO_2-water nanofluid and polymer 3330 in the coiled tube were investigated. The effects of the Reynolds number for 2 vol. % nanoparticles which consists of 25 ppm PAM (3330) determined at the constant temperature of 24°C. It was observed... 

Platelet nanoparticles could dramatically decrease permeability of polymeric film where increase considerably its physical -mechanical properties. Bio based (Biodegradable) polymeric materials such as starch based polymeric films show very weak mechanical and high oxygen and water vapor permeability. Graphene oxide (GO) could increase mechanical properties of starch based polymer where decrease its permeability dramatically. Addition of chitosan also could increase antibacterial and antifungal of films and decrease permeability of films considerably. In this research nanocomposite of Starch/Chitosan/GO films have been prepared by solution method and its morphology, permeability, physical... 

In past two decades, the direction of oil and gas exploration has moved towards deep water drilling. The pressure and temperature in these zones are ideal for gas hydrate formation that can cause serious and sometimes uncontrollable issues during drilling operations. Gas hydrate formation while drilling can cause problems such as occurrence of kick and blowout, plug chock and kill line, and change in rheology of drilling mud. On the other hand, nowadays, nanotechnology has created an evolution in engineering sciences and because of the wide range of this science, drilling industry is affected like other industries. In the meantime, because of high yield, high stability and various methods of... 

Smart heat-sensitive polymers play a unique role in drug delivery systems due to reversible behavior in response to environmental changes, especially temperature changes. Among the heat-sensitive polymers, UCST polymers due to their specific behavior and very little-known polymers with this feature are the subject of many new researches. In the present study, New designed temperature-sensitive polymers with UCST capability based on acrylamide and vinyl acetate were synthesized. These copolymers were synthesized in different percentages of acrylamide by free radical polymerization in solution conditions. All polymers compounds were characterized by H-NMR, FT-IR, DSC and GPC measurements. The...