Sharif Digital Repository

The pervious Iranian seismic code has not considered the ductility parameter in the seismic design of (steel) structures. , therefore; seismic vulnerability and retrofit of existing steel structures is becoming a vital engineering problem. Common ways of seismic retrofit such as adding a shear wall or bracing the structure cause huge forces in elements and foundations. Rehabilitation on the foundation has many constructional problems and leads to long down time. As far as known, the Infill Walls increase the lateral stiffness of frames and lead to reducing the period of the structure. Therefore, to have a reliable design, it is important to consider the effects of Infill Walls. It can be... 

In this thesis, the hardness of Ni-Cr alloys is optimized by design of experiment (DOE) method (Central Composite Design) in pulse electrodeposition performed in chloride solution. Various parameters were evaluated for finding significant factors in pulse electrodeposition of Ni-Cr alloy. Frequency, duty cycle, current density and temperature were selected as effective factors. 30 experiments were designed by the central composite design method. Analyses of Variance (ANOVA) were performed on the results of these 30 experiments. The best models which can predict the hardness, Cr content, deposition rate, thickness and cathode efficiency of Ni-Cr alloy electrodeposits were found and... 

Ni-P alloy coatings were electrodeposited using pulse current in a watt type bath in various conditions. The influences of different parameters were investigated and optimized for the highest amount of coating hardness using the Design Of Experiment (DOE) method. The optimized deposition parameters were current density 23.7 A/dm2, duty cycle 75%, frequency equal to 188 Hz, temperature equal to 70ºC and 17.5 gr/l of H3PO3. The DOE prediction of hardness for the optimized coatings was between 700 and 750 the achieved micro-hardness was about 725.8 HV. It was obtained that an increase of the current density will improve micro-hardness, decreases P content and increase deposition rate. Also, the... 

The optimal design of a ground-coupled heat pump (GCHP) system with vertical ground heat exchanger (VGHX) includes thermal modeling of the system and selection of optimal design parameters is presented in this research. Then, by applying Nelder-Mead optimization algorithm, an objective function (Total Annual Cost which is the sum of annual investment and operating costs of the system) is defined and minimized, exposed to specified design constraints. Also, Genetic Algorithm is used to verify the optimal design process. In order to evaluate the accuracy of a presented model, the optimum values of a heat pump design parameters includes saturated temperature/pressure of a condenser and... 

This research aims to study fundamentals of design as a science for possible use in special structures. Special structures are referred to those structures that designers’ knowledge for which are insufficient. Designs of such structures are complex in the sense that we lack all necessary elements of design matrix; as well as proper steps to reach the unknowns. Introducing appropriate design strategy for such structures; we show how a design could be developed without specific needs for trial and errors. In this work, various design methodologies and especially “Axiomatic Design” have been examined. In addition, functional requirement and associated design parameters for structural design are... 

Wireless Sensor Networks (WSNs) are comprised of small sensor nodes with very limitedstorage, power and computational capabilities. The nodes in wireless sensor networks should be able to communicate with each other in order to accumulate information and to relay it to a base station in a secure manner. Since this communication often takes place in a hostile environment, encryption and/or authentication should be used. This requires the establishment of secure keys between the sensor nodes in the WSN. The constraints of such a lightweight distributed computing environment lend itself to the use of symmetric cryptography to provide security services. The lack of central infrastructure after... 

Structural best management practices (BMPs) are often used to mitigate the impact of storm water runoff on receiving waters. Vegetative filter strips (VFS) are an example of a structural BMP that has been used to treat storm water and highway runoff. In this study (the first in Iran), field-quality data were collected from a native VFS treating urban runoff in North of Tehran. At first field data were used to test the design concepts of the VFS treatment train and to modify and calibrate simulation model for evaluating the impact of physical factors such as slope, type of vegetation and impermeable surface on sediment removal then more field data were used to evaluate and modify the... 

To obtain solutions containing Titanium, leaching of Ilmenite Concentrate of Kahnooj and its Slag by Sulfuric Acid 98% in various Conditions are Studied. Screening tests by Fractional Factorial method were designed, at this step effects of Temperature, Acid Concentration, Particle Size, Solid to liquid Ratio, Time and Stirring Speed were investigated and It was Concluded that Temperature, Time, Acid Concentration and Particle Size were the effective Parameters in both leaching process of Ilmenite and Slag. The Temperature, Time and Acid concentration had positive effect, whereas the Particle Size had negative effect. After screening step, effective parameters were optimized by Rotatable... 

In a single chemical plant, the operation of each unit operation is not independent of each other. In the other hand, the main operations are performed in reactors following by several separation steps including distillation and purification units. The total energy requirements are sullied by the heat exchanger networks. The performance of these systems is improved by integration and intensification of the reactor and distillation column in a single unit. The main objective of the present work is to provide an effective design approach to intensify the reactor and distillation column. In a reactive distillation column, the reaction and separation is done in a single unit. Increasing... 

The optical properties of semiconductor nanoparticles are dependent on their size. Then, the important problem in synthesized semiconductor nanoparticles is controllable of their size. In this research ZnS nanoparticles were synthesized by hydrothermal method and taguchi design of experiments and study on effect of solvent, reaction temperature and molar precursor ratio on band gap and particle size of ZnS . The UV-Vis spectrum was carried out for measurement of band gap and the size of nanoparticles by using the effective mass approximation. The X-ray diffraction patterns exhibited a cubic zinc blende structure for the nanoparticles. The ZnS:Mn +2 nanoparticles werw synthesized. With... 

In a macro view point, it can be said that housing demand in recent years is making the construction industry one of the main sectors of Iran’s economy. On the other hand, analysis of seismic risk in the country with regard to the geological conditions, the faults, and the seismic records of mega city of Tehran is depicting the delicate location of the Iranian capital. This city is selected as a case study in this thesis that has a high probability for the event; where this event has also been classified as a devastating earthquake ever. Due to the involvement of private sector in construction industry, the need for establishing a system of strict control on quality of construction of the... 

Seismic isolation is a method for seismic-resistant design of structures against earthquake and is one of the important control of structures technologies. Codification and publishing of codes for design of seismic isolation takes place widely since 1980s and this codification has undergone extensive evolutions during its developing process. In this project initially the developing process and fundamentals of codifying regulations of seismic design have been investigated and then the developing process of codifying regulations of seismic isolation in current important international codes like ASCE7-05, Eurocode 8, and Japanese code has also been considered. After considering these two... 

In order to manage a complex system, one way is to divide it into smaller parts. That’s the reason airspace in each country should be divided into sectors. Currently, these sectors have fixed areas and each is controlled by a number of air traffic controllers. However, the traffic crossing these sectors is considerably dynamic, which means the traffic density and its distribution varies seasonally, weakly and even through the 24 hours of a day. Moreover, weather conditions and security and military issues make constraints to some of these sectors. This sometimes results in some high traffic sectors while some others have very low traffic density which causes two main problems. One is that,... 

Decision making is one of the most critical issues in engineering field. The Axiomatic Design is recently known as one of the most robust tools for decision making task. Axiomatic design is a engineering theory that provides a systematic framework for decision making using two axioms. These two axioms called Independence and Information axioms are both used to do the task.In this thesis, the information axiom is used to select the best machine (operation) for manufacturing cylindrical parts. To do that, three criteria including surface roughness, dimensional accuracy and cost have been chosen.Finally a comparison to the result of this methodology and the result of Analytical Hierarchy... 

Research on the characteristics of the near field earthquakes has been very popular in recent years due to the considerable damages they have caused to the structures located within the vicinity of seismic sources. The incapability of response spectra for structural damage assessment has been revealed through recent investigations. The recorded data show that the near field earthquakes are often accompanied by a large energy pulse in the beginning of the records caused by the so-called directivity phenomenon. That has encouraged many researchers to study the possibility of using the velocity pulse of these records to evaluate the imposed seismic demands on structures. Thus, investigating the... 

Forging process is recognized as the high speed method, economical and with ability to produce high strength parts between metal forming processes. Preform design is the most important step in forging process. In the past this work was done based on experiences. In the complex parts because of error in design there was probability of diverse dies, so that method needed to spent so many times and costs. However recently with progress in computer programming we don’t need to produce diverse dies but spend many times. In this field many investigations are done to dispose designers skills, so forging preform design based on inverse finite elements method is denoted for this gold. In this thesis... 

In recent years, by development of computer and analytical software, engineers intended to do complicated and delicate dynamic analysis instead of static ones. This cause reduction in uncertainty in structures analysis and designing, that improves environmental, economical, and safety performance. Currently there are two common methods which are accepted in major building codes, they are spectral and time history dynamic analysis which the former analyzes structures by using design code spectra based on determination of structures’ dynamic haracteristics, and the latest do it by imposing ground motions on the structure. The spectral dynamic analysis method has some errors and causes... 

Light cold formed steel structures have a wide use in building constructions and industrial projects due to their economical advantages, rapid erection and installation and capability for industrial mass production. The main objective of this thesis is to investigate the seismic behavior and to study the seismic requirements for design of Light steel frames (LSF) structures. The cold forming technique, and the basic concepts of cold formed steel members design have been investigated and the basic concepts of seismic design of light cold formed steel structures is discussed. In order to investigate the performance of steel strap framed wall systems and estimate its response modification... 

In this research a model is proposed which determines flight frequency and aircraft routing for an airline network. It is supposed that origin-destination demand, costs, number of aircrafts in the fleet and their capacity, aircraft maximum daily utilization hours and origin-destination fares are given. The model attempts to maximize airline profit and determines flight frequencies, number of passengers carried between two cities and number of passengers who travel with an indirect flight, considering fleet constraints and an operational aircraft routing.The model is tested with a hypothetical numerical example. The results indicate that the model uses maximum aircraft capacity and daily... 

In recent decades, most of the codes have placed a high value on Performance Based Design of structures; however, these methods are computationally complex and time-consuming, and caused researchers to seek new and efficient methods to investigate performance of structures under different intensities of seismic loading. The Usage of Endurance Time method (ET) and thus reducing the size of analysis can be a useful tool for excuting Performance Based Design of structures. Endurance Time analysis is based on time history analysis, but in this method structure subjected to an intensifying acceleration function and different damage indices of the structure are evaluated through analysis time. The...