Sharif Digital Repository

Thermodynamic analysis of a system is a method for recognizing the type of energy transmission between system and surrounding environment. It also helps to find how macroscopic properties of the system change during this process. This analysis is based on first and second laws of thermodynamic. The first law expresses conservation of energy and inspects quantity of energy transmission but doesn’t evaluate quality of energy. The second law expresses quality of energy and the ability of doing work. The analysis that uses both of the laws is named exergy analysis. By exergy analysis the place of useful energy losses in the system can be determined. In this research the exergy analysis of... 

Many industries such as olive oil mills, petroleum refineries, petrochemical plants and oil field operations generate saline wastewaters containing phenol. The aerobic moving bed biofilm reactor (MBBR) was investigated in this work in order to assess its performance for the degradation and chemical oxygen demand (COD) removal of phenol as the sole substrate from saline wastewater. The effect of inlet concentration of phenol (200–1200mg/L), hydraulic retention time (8–24 h), inlet concentration of salt (10-70gr/L), organic shock loading, hydraulic shock loading and salt shock loading were evaluated on the performance of two 10-liter MBBR seeded with mixed culture of active biomass... 

Over the last years, research about writable virtual machine introspection has been started. This approach has the benefits of readonly virtual machine introspection. Additionally, it has more applications, such as automated defense against malware programs, than the read-only approach. In the read-only VMI, data is gathered from virtual machine hardware states and then analysis in virtual machine monitor. In writable one, hypervisor can modify virtual machine kernel state. Consistency issue is an essential challenge for out-vm writable VMI. In the best of our knowledge, only one implementation try to solve this consistency issue. However it cannot resolve this issue completely. Other VMI... 

The use of metal matrix composite materials (MMC) in aerospace structures and engine parts has become more frequent recently. These materials are composed of metal matrices reinforced by hard discontinuous ceramic fibers, usually oriented longitudinally within the matrix, and due to the stability of the mechanical properties, including the hardness and the strength at high working temperatures, have found various applications.Stress transfer from the matrix to the fiber is known as the most important mechanism governing the deformation and the fracture response of such MMCs. The stress transfer characteristic of fiber reinforced composite materials under various mechanical and thermal... 

The average annual turnover of Iranian mutual funds is 330 percent during the years 2011 to 2017. Such a high-volume trading imposes substantial transaction costs on the funds and their investors. Transaction costs comprise four different types of costs: In addition to taxes and commissions, there are other transaction costs originating from bid-ask spread and price impact, which need more complicated procedures to assess. By using high-frequency data and the information in the fund’s seasonal financial statements, the transaction costs of fifteen Iranian mutual funds are estimated. These funds spent 11 percent of their value on the trading costs per anum. Furthermore, the relation between... 

The aim of this paper is to investigate the effects of Iranian Chief Executive Managers and board of directors on the outcomes of their firms. First, by exploiting the information about changes in the combination of managers in 488 firms in Tehran Stock Exchange and Iran Fara Bourse, this study seeks to give an insight about managers’ labor market in Iran. Then, after combining these data with the obtained information from the firms’ financial statements, we run a set of regressions to identify whether managers have significant effect on the firms’ behaviors and performance. The results of this investigation show that a significant portion of changes in firms’ outcomes can be explained by... 

Using Aspen Hysys to simulate burners and furnaces has been the focus of several studies in recent years. According to the studies and investigations carried out in the field of optimal design of the furnace, heating the air is one of the possible tasks to improve the performance and increase the efficiency. According to the obtained results, by adding air preheat, the efficiency increases from 92% to 96%. Also, to validate the simulation, two furnaces from Sepahan Oil Refinery furnaces were simulated in the field of oil production, which were simulated with an error of less than 1% in duty calculation, and according to the general results obtained, adding air preheat can increase the... 

In traditional networks, network management was performed locally at the data layer by switches and routers. This approach made it difficult to make optimal decisions with a comprehensive view of the network. Software-Defined Networks (SDNs), by separating the control layer from the data layer, introduced a centralized decision-making unit in the network. This decision-making layer, equipped with overall network information, makes decisions that enhance the overall efficiency of the network. Software-defined networks provide customizable traffic control by storing numerous rules in on-chip memories with minimal access latency. However, the current on-chip memory capacity falls short of meeting... 

A Focal Plane Array (FPA) consists of one or two dimensional array of sensor elements and is widely used in imaging systems. Generally an FPA can be divided into two main parts: Sensor array and read-out/test circuit. In this thesis we design and implement a test circuit for an FPA that works in 77K. The circuit will be attached to the sensor to detect and amplify its very low level current that is in the range of 10 pA to more than 10 nA. Reducing MOSFET temperature from room temperature (300K) down to liquid nitrogen (77K) will greatly changes its parameters and characteristics such as Threshold Voltage and carrier mobility. However MOSFET models in low temperature are either... 

The determinants of business cycles and how to deal with them are amongst the most important issues in macroeconomics. Using the annual data between 1980 to 2012, available for six oil producing members of Gulf cooperation council, we draw a connection between trade structure and business cycle synchronization. In fact, we try to answer whether the same trade structure in these countries with very similar characteristics has led to synchronized booms and recessions among them. Assuming cross correlation, different estimation methods, including common correlated effects, confirm the positive significant effect of trades tructure on business... 

This paper examines the effects of institutional price pressure caused by severe inflows and outflows of capital by studying mutual funds transactions in the Iranian stock market between 2010 and 2017. According to the findings, mutual funds that experience severe outflows tend to reduce or eliminate existing positions in their portfolios, which creates a severe price pressure in the securities held by distressed funds. This price pressure caused by a severe outflow of capital leads to decrease stock prices below their intrinsic value. So investors who buy shares that sold by mutual funds earn abnormal returns for providing liquidity. On the other hand, funds with severe capital inflows tend... 

Smoke is the largest cause of fire related deaths. A smoke control system is an engineered system that modifies smoke movement for the protection of building occupants, firefighters and properties. Unfortunately, in case of fire, stairwells and elevators are frequently filled with smoke, preventing effective evacuation. Many smoke control systems use mechanical fans to control smoke by providing positive pressure at strategic locations. Pressure difference across a barrier can control smoke movement by preventing smoke on the low-pressure side of the barrier from migrating to the high-pressure side. Building designers use codes and rules of thumb to design their building against fire.... 

One of the typical method for analyzing Iran stock market is comparing Earning Yield of stock with interest rate or bond yield to maturity. In this paper we have literature review that shown FED model does not have any theoretical fundamental so then discuss about FED model merit for asset pricing. Results show that FED model does not work in Iran stock market and we didn’t see any long run relationship between earning yield and interest rate. Also this paper show evidence about inflation illusion and mispricing in Iran stock market and propose that Iran stock market is undervalue because of inflated economy  

Although financial theory recommends investors to diversify their portfolios to reduce their overall unsystematic risk, some fund managers hold their portfolios concentrated in specific industries. This thesis study the relation between the industry concentration and the performance of Iranian equity funds in the period from 1392 to mid-1397. This relationship has been investigated in two approaches of dividing funds into portfolios by their industry concentration index and multivariate regression model approach by considering some characteristics of funds. To measure the performance of funds, two sets of measures based on the analysis of information of fund holdings and time series of fund... 

Studies of the ownership structure of companies in different countries demonstrates that pyramidal ownership structures and business groups are present and even dominant in many countries. This type of structure allows the ultimate owners to leverage their capital and control more capital in the economy. Studies related to this type of ownership structure, scrutinize various motivations that have caused the formation of this type of ownership structure. Some studies emphasize the destructive role of business groups, such as tunneling and creating monopolies through common ownership in competing companies, and as a result, consumers and small shareholders are expropriated. Others, relying on... 

Temperature reduction from room temperature to liquid nitrogen temperature has a significant effect in improvement of semiconductor devices operation such as field effect transistors. Nowadays cryoelectronics as a considerable branch of electronics is concerned by several groups. In order to optimize the procedure of low temperature IC design and fabrication we investigated the temperature effects on different parameters of MOSFET in this thesis. Several transistors in a variety of channel lengths were fabricated in different technology files. Wide measurement experiments were done on these transistors in order to find their drain current vs. drain to source voltage characteristics. From... 

In this investigation, effects of static restoration phenomena on microstructure and mechanical properties of A286 superalloy were studied. Therefore, single hit and double hit hot compression and hot rolling with different delay time at temperatures of 1050 and 1100 °C in strain rate of 0.1 and 6 s-1 were applied. In addition, annealing of cold compressed and cold rolled samples with various amounts of strains in temperature range of 1000-1100 °C were performed. Finally the best method for forming of A286 superalloy was proposed.Single hit hot compression test results shows that dynamic recovery and dynamic recrystallization occurred at temperatures of 1050 and 1100 °C respectively.... 

In this project a high spectral purity C-band (4.25-5GHz) frequency synthesizer has been analyzed and designed and implemented in CMOS 0.18μm technology. This synthesizer has been embedded in TX path of a transceiver module as a frequency translator for digital phased array system applications. The system includes Phase Locked Loops (PLLs) and Direct Digital Frequency Synthesizer (DDFS). Due to desired Low spur level (90 dBc) in C-band, system level design, frequency plan, choosing proper PLL topology and etc. have been considered in details. One of the important challenges in system design is the signal spectrum purity. In other words, the system should produce minimum phase noise. Output...