Sharif Digital Repository

The injection process on cell is a very accurate and sensitive operation. This method is used for several new invented approaches such as tracytoplasmic Cell Injection or drug delivery. Controlling the injection force in micro scale is one of the problems of mentioned operations. Current huge and expensive laboratorial devices are helping the operators to do injection operation with :nore success. In this study a simple and novel microelectromechanical (MEMS) mechanism for doing injection process automatically on the biological cells is proposed. In order to controlling this device properly, we should model and simulate the operation condition from initial position to final condition. This... 

In this thesis, the behavior of proposed moment resisting precast beam-column concrete connection under cyclic and monotonic loads is investigated. In this study, the finite element models of precast and monolithic middle and corner connections are created. The results of finite element analysis under cyclic loading is verified with existing experimental results based on failure mode, ductility, energy dissipation capacity and flexural strength. Based on the results of nonlinear finite element analysis, the analytical behavior of samples is in good agreement with experimental results and finite element analysis of proposed precast connection can be replaced with supplementary tests. Then the... 

Taking advantage of aluminum and its alloys in industry is increasing. A common method in metal forming is hot forming. In this condition a precise prediction of flow behaviour of the alloy is necessary to achieve a product of desirable mechanical and physical properties. In this situation, influence of parameters such as chemical composition, temperature, strain, strain rate as well as recovery and recrystallization phenomena should be considered and by using a suitable model, the metal behavior prediction is possible. Distribution of coherent Al3Sc dispersoids in high volume fraction accompany with Al6Mn result in strengthening to this alloy. Because of the high stacking fault energy,... 

The leads with heavy current passing through the covering plates, and the winding in a transformer, are sources of eddy current losses. Due to this loss some regions of tank wall are subject to serious local overheating. It affects the safety and reliability of this expensive bject and power delivery.Heavy current in large power transformers and special type transformers give rise to a concentrated passage of eddy currents which in turn cause high local losses and overheating in the metallic parts especially in the steel tank walls of transformer.This local overheating is dangerous for transformer oil and the solid insulations. Therefore the calculation of losses and proper design of... 

Setar is a traditional Persian musical instrument. Nowadays, Setar is one of the most common musical instruments in Persian music. A systematic method for Setar production modification has not been introduced yet. This work is the first scientific work about analysis of this instrument. The aim of this study is to undertake early steps for Setar quality improvement. In this thesis, after analysis of the wood using in Setar construction, numerical and experimental methods have been utilized to analyze this instrument. After that, some works has been performed to extract an objective function which can judge about Setar quality. The results show good agreement between experimental and... 

The fabrication of micron-sized instruments MEMS have been in fast progress in different fields of science and technology such as those of chemical processes in chemical engineering, propulsion in aerospace industries, microchip cooling and inkjet printers in electrical industries, and medical appliances in medical and biomedical science. They have forced the manufacturers and researchers to work and think in fabricating such small-scale sizes. However, the complexity of fabricating MEMS with moving parts has also promoted the manufacturers to think of alternative ways. For example the use of moving parts to pump fluid in such devises causes such difficulties and the researchers could adopt... 

The aim of the work presented in this thesis is deal with some of the aspects in the FEM analysis of sandwich panels containing holes which comprised with foam core. It is a new topic in this field; so the activities that have been done about this case are poor with respect to its performances in engineering. The main emphasis is placed on the treatment of the foam core since the core often is the weakest part of the sandwich and therefore in many ways governs the capacity and lifetime of the whole sandwich structure. Because of increasing application including construction, aircraft and transportation, marine and etc., different load conditions are considered for the analysis and... 

The work reported in this dissertation is the result of a joint venture of biomedical scientists and engineers for understanding human middle ear mechanics through finite element modeling and analysis. The main objective of the research is to explore the middle ear dynamics by using an accurate finite element model of the human middle ear. The research started with developing a systematic and accurate geometric modeling method that can be employed to reconstruct the middle ear from the histological sections of a human temporal bone. Using the method, a solid model of human middle ear was constructed which reveals excellent accuracy in geometry. Then a finite element model of the human middle... 

In this study, hot extrusion of AA6061-%5 SiCp composite has been predicted and flow behavior of material during deformation process has been investigated. At the first step, hot compression tests have been carried out to obtain the flow behavior of the material at different temperatures and strain rates. In the next step, an FE-based temperature-displacement coupled model by employing ABAQUS software has been proposed in order to solve the energy and heat transfer equations and to determine the required energy and force for the extrusion process. Experimental investigations have also been performed to verify the proposed model. Comparison between the results from the model and the... 

Purpose of ongoing thesis is providing a tool for suitable modeling, increase efficiency and decrease construction cost of solar absorption heat pump. At first, the solar absorption heat pump is modeled by the thermodynamic laws. Then, this model is converted to the new standard mathematical programming model using exergy and thermodynamic Analysis with considering all technical and economic constrains. This mathematical model is optimized by Genetic algorithm (GA). Because of the nonlinear objective function and the constraint, GA is used as optimization algorithm. After applying GA, optimized parameters of cycle heat exchanger designing and its electricity consumption are calculated.... 

Recently in civil engineering prestressed concrete slab applications is increasing, and typically results in overall economy and provides satisfactory structural performance. In The present work, two-way prestressed concrete slabs have been considered and during designing process with the ACI-2005 code and due to economic plan, prestressed slabs were studied in transfer, service and final conditions. ACI code insists that two-way prestressed slabs shall be classified as class U (without cracking) that means section must be untracked in all conditions (code reference 18.3.3). In addition, two-way prestressed slabs must be prestressed in both directions for 100% of load, and this means that... 

Suction caisson is a relatively new technology which was introduced about 30 years ago for the first time and after several investigations, was found its position in the oil industry and construction of anchorages, during previous decade. So nowadays, it is the most effective and economical choice as the mooring of offshore structures in comparison with the other foundations. Suction caisson is a hollow cylinder with an open bottom and a closed top. After placement on the seafloor, the caisson first penetrates into the soil by its self weight and then inserts into the ground by pumping water out of it. Although many researchers have attempted to understand the behavior of suction caissons... 

In the recent years, medical application of robots has been widely developed. Transforming open surgeries to close surgeries has distinguished this novel method to decrease limitations in this type of surgery. In this procedure, two or three small incisions on the skin are used as guides for robotic instruments to enter the cavity, to improve the surgeon’s manipulation and function in surgery. One of challenges in this field is surgeon’s training for laparoscopic surgery. Surgical simulators are used to solve this problem. Lack of instrument for large organs gripping and tissue palpation loss are existing difficulties in available surgical simulators in such a manner that surgeons has no... 

Estimation of power transformer no-load loss is a critical issue in the design of distribution transformers. Any deviation in estimation of the core losses during the design stage can lead to a financial penalty for the transformer manufacturer. In this project an effective method is proposed to determine all components of the iron core losses applying a combination of the empirical and numerical techniques. In this method at the first stage all computable components of the core losses are calculated, using Finite Element Method (FEM) for modeling and analysis of the transformer iron core magnetic problem. This method takes into account magnetic sheets anisotropy, joint losses and... 

Nowadays, the use of advanced composite materialsin different structureshas been increased and many industriesextend application of these high-tech materials because of their very high ratio of strength to weight and variation in ply configurationsuch asdifferent fiber angles which can control the response of these planes due to design requirements.One the most recent applications of such materials inreinforcing various structures are preventing crack propagation in aircraft structures and strengthening buildings against earthquakes which have been developed considerably. But, a lot of intact topics in this criterion are available which should be studied carefully. So, according to what was... 

Nowadays, science of nano technology has been growing quickly in the past decade. Scientists implemented this technology in bioengineering, electronics and medicine extensively. Nano scale engineering is one of the interests of researchers, nano bearing as a nano scale structure and as an important part of nano machining plays an important role in micro and nano devices. The role of nano bearing is to decrease energy dissipation and increase the efficiency of nano machines. The main purpose of this study is to design and analyze an optimized nano ball bearing. In this regard, a new spherical super element is designed and presented. This super element is implemented in simulating the... 

In order to improve the fatigue performance of torsion bar, induction surface hardening is performed. The aim of the present study is failure analysis of torsion bar and improvement of manufacturing process. Induction hardening was simulated using finite element method. As a result temperature history and residual stresses were obtained. Temperature and residual stress distributions are affected by the component geometry, the material behavior and the induction treatment parameters. Based on the residual stress distribution and the external fatigue loads, cracks can nucleate from the surface or below the hardened layer. Therefore, it is very important to determine the residual stress... 

Performance of reinforced concrete frames is highly dependent on detailing of the joint connections between its members, such as beams and columns. To have a good structural behavior, joints must show ductile behavior and designed based on the philosophy of strong column-weak beam. In the case of sever lacking ductility, strength or even rigidity of the connections, or having a weak column-strong beam, in the existing structures, there is a need for seismic upgrading of the connection. There are several ways for seismic upgrading of this type of connections.In this research, using steel plates for seismic upgrading of Concrete Beam-Column connections subjected to axial and cyclic loads has... 

In this study, transient diffusion of drug into the intervertebral disc is considered. The amount of Diffused drug from the blood into the intervertebral disc of dog is measured and concentration of drug is calculated for each region of the intervertebral disc including nucleus pulpous, inner annulus fibroses and outer annulus fibroses. Using finite element method, it is shown that the amount of drug diffusion into the intervertebral disc is affected by some parameters such as the type of drug, dose if drug and endplate calcification. This research is done in two parts: In first part, diffusion of drug (sulphate) into the dog intervertebral disc is investigated to compare the obtained... 

Using materials with better mechanical properties is always advantageous. Many sectors, including automotive and aerospace industries, are always seeking new materials with better mechanical properties and lower weight. A lighter vehicle means lower emission and higher fuel efficiency. Thus, developing new methods to investigate novel materials is very important. One of these novel materials are Metal Matrix NanoComposites (MMNCs). MMNCs are fabricated using nano scale particles embedded in metallic matrix. High strength, stiffness, and hardness are the three most important mechanical properties of MMNCs. Introducing a suitable way of modeling these materials is important since it will...