Sharif Digital Repository

In this work, a numerical investigation on shell side performance of a continuous helical baffle helixchanger along with smooth and helically ribbed tubes using CFD commercial code, Fluent, has been performed. The results of simulation for this type of exchanger were compared to a similar heat exchanger with segmental baffles. The geometries are created and meshed using Solidworks and Ansys Meshing softwares, respectively. Mesh generation is carried out using unstructured tetrahedral type elements. Element size (or number of elements) are chosen in such a manner that maintain accuracy and reliability of results in a reasonable run time. Simulation validation were carried out by comparison of... 

Todays, one of the most important problems is optimal allocation of capital to different investment options that many researchers studied about this problem and presented a lot of solutions. In this thesis, we solve portfolio optimization problem to maximize the return of investment. The options of investment are different kinds of stocks, gold coins and we consider bank deposits as a risk free asset. We apply the problem in multi period and we can buy and sell stocks and gold coins in each period. To improve the efficiency of the proposed models, we use real data and consider transaction fees. The return of some options is uncertain, so we use robust optimization approach. At first we apply... 

Fast penetration of internet among people caused serious changes in businesses and helped them to migrate from classic systems to modern trades. Beside considerable benefits of this evolution like decreasing costs, increasing efficiency, increasing reliability, expanding market and ease of customer relationship management, some risks endanger life a business. Retailers as the last ring if a business chain, mainly encounters a hardship of risks. In this study, after identifying and prioritizing possible risks demand risk identified as the most important point to focus. After analyzing this risk, we try to propose mitigation solutions  

In this research, the effect of political system on economic performance of resource abundant countries is studied. We use political economy litreture to develop a theoritical model in this issue. Here, the politcal systems are divided to democracy and dictatory and in each of them other institutional variable will be introduced. Policy indicator is based on the difference between social welfare in each situation and its optimal amount when maximized. We show that if democracy does not come with high accountability it reduces social welfare more than dictatory. Also, if politician are myopic, democracy aggravates economic performance in those countries. In addition, easy access to income... 

In this study, the effect of temperature on the microstructure and electrochemical properties of the NMC batteries has been studied. An extensive set of accelerated aging tests has been carried out employing a Li-ion high energy 18650 system (2.2 Ah, negative electrode: carbon, positive electrode: Li(Ni0.5Mn0.3Co0.2) O2. Different influence factors on cycle aging, such as temperature and discharge rate have been investigated. The aged 18650 cells have been inspected via scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), impedance spectroscopy, and X-ray diffraction (XRD) after disassembly to find more information about the chemical reasons of the degradation and... 

Iran is one of the richest historic countries in the world, as extention of cultural heritage and historic building is unique. Infestation of lichens to those heritages for doing strategic actions wants the coordination of systems and organizations and universities. All the actions that do in this field, about the conservation and preservation of heritage made by stone related to architecture, be limited to lasers, electromagnetic waves, and application of jet methods such as sand storm, water jet, and prior to this mechanical and handful methods that approximately all be destructive. Application of nanoparticles of titania, as a smart photocatalytic material with antimicrobial and... 

The aim of this study is to remove pharmaceutical pollutants through a photocatalytic approach. A layered double hydroxide (LDH) structure was synthesized with the assistance of a metal-organic framework (MOF). Initially, MIL-101(Cr) was synthesized using trivalent chromium ions and subsequently transformed into a layered double hydroxide structure with divalent nickel ions. To further enhance this process, MIL-88(Fe) was prepared using trivalent iron ions, composited with MIL-101(Cr), and then converted into an LDH structure using divalent nickel ions. The resulting photocatalytic composite was fully characterized, and its efficiency in degrading the pharmaceutical compound meropenem was... 

Gas transmission networks play an important role in multi-vector energy networks. Therefore, reliable and efficient control of gas transmission networks with the minimum energy consumption is utmost task and is still an active research area. This work, introduces a distributed, model-free, and game-theoretic approach comprising a simultaneous game followed by a sequential game, to achieve the control objectives in gas transmission networks. The cooperative game approach is adopted for this purpose. In the proposed method two fuzzy inference systems have been used to obtain the payoff of each player in the game of gas transmission network control, the first one has been used to determine the... 

In this research, Synthesis, characterization and photoelectrochemical application of two dimensional MoS2 and WS2 nanosheets have been carefully investigated. And finally, based on theoritical and experimental analysis results, the mechanisms of the observed photoelectrochemical (PEC) activities were suggested.The ab initio density functional calculations about Mo1-xWxS2 monolayer deposited over a TiO2 (110) substrate revealed a shift in band position of the Mo1-xWxS2 in favor of photoelectrochemical water splitting. Moreover, increase of W concentration in Mo1-xWxS2 could improve the charge separation and increase the effective mass ratio leading to an extension of the electron–hole... 

Fighting contagious microbial diseases is considered a serious health issue, which has attracted much attention in worldwide. Thus, development of new materials based on nanostructures as a new generation of antibiotics to address this challenge has been of interest to researchers in recent years. Nanostructures based on metallic oxide semiconductors such as oxides with light absorption, production of electron-hole pairs in needle like structures cause tearing bacterial membrane and eventually destroy the bacterium. To this end, we designed experiments to study mechanism and physics governing the process of bacterial degradation to determine the best conditions for inhibiting bacteria... 

Government intervention in markets may go beyond the market regulation. Interventions may cause some idiosyncratic price distortions. It means the relative prices of factors to become different among firms. Therefore, micro conditions for firms will be changed. These will result in misallocation of factor production between firms and change in manufacturing TFP. According to data from about 14000 medium and small industrial firms in Iran, removing misallocation of production factors (capital and energy) and output idiosyncratic distortions between industrial firms would result in 115 percent increase in manufacturing TFP.

 

The purpose of this research is the extraction of socio-economic factors (separation of household and household members) that affect the use of banking services in urban area of Iran. In this study we used data of the "family access to financial services in urban areas of Iran in 1387" that has been sampled by the department of economic statistics of central bank of Iran. The statistical information of this organization is in form of completed questionnaires and based on household addresses in a city and contains of 6055 urban household's information. In this project 15922 persons have been studied in urban households include the caretaker and the other family members. In addition to...