Sharif Digital Repository

Nowadays, the world is full of multi criteria decision problems and all the people should make decisions in different situations. Sometimes, the result of a decision problem is so important as a wrong decision may result in a loss that cannot be compensated. Therefore a decision making tool seems as a must. On the other hand, in this era of rapid social and technological change leading to increasing life complexity, sensitivity analysis is an important issue in all decision making processes. Analytic Hierarchy Process and Analytic Network Process, as two common tools for multi criteria decision making, are widely used throughout the past decade in different fields. Designing the model and... 

Products on Research and Development (R&D) are followed by Technology development. Projects on R&D are cost intensive and considerable of financial resources should be allocated. Optimal allocation of resources could be managed through cost effective strategy. Hence, a “Model for planning and development of technology” has been developed in the present work, which lends itself to the analysis of the industrial application of planning of technological development based on minimizing costs of both development and application of a technology. Mixed Integer Programming optimization model has been developed which enables studying the structure of R&D activities. This model is based on the concept... 

As a problem, generally, energy security components do not interfere with the calculation of the optimal energy supply situation. In this paper, we are looking to find a solution to make a framework of the impact of energy security on energy supply in order to obtain comprehensive analysis of the economic optimal point. Method is based on the competition of energy costs to meet demand during the study period. Threats that have been addressed in the energy security are seen as risky and stochastic parameters in the model. The nature of these parameters is of uncertainty type, therefore, based on the probable scenarios of the stochastic model, the perspective of the energy supply system is... 

In the recent years, there has been an increasing attention toward usage of ultrasonic for enhanced oil recovery practices. But, thorough knowledge of active mechanisms and spreading and characterization of developed fingers during this practice is not available. From the other hand, due to limited amount of light oil fields, more attentions towards recovery from heavy oils is the need of the hour. Documents show that the big issues during the enhanced oil recovery from heavy crudes are high density of reservoir oil as well as poor development of fingers during injection due to high mobility ratios. In this study, results of ultrasound effect on the heavy oil recovery and its effect on the... 

The aim of this thesis was to find the optimum retention time for treatment of synthetic petroleum wastewater by a wastewater treatment system made with a bucket, mineral material and earthworms residing in a vermibed. In order to make the desired flow happen, height difference was utilized. The polluting substance used for making wastewater was BTEX. As the wastewater was synthetic, the concentration was also a variable. The ultimate soluble concentration was 3200 mg/l and more concentrations were not tested. Parameters such as number of worms, worm’s growth rate and their distribution pattern, humidity amount and distribution and worm’s acclimatization time during organic loading shock... 

In this work, wool keratin/polyethylene oxide (PEO) nanofibrous scaffolds were fabricated by electrospinning method. Bacterial cellulose nanofibrils (BCNFs) were embedded in the electrospun keratin/PEO nanofibers. Incorporation of BCNFs into the nanofibers enhances their hydrophilicity, mechanical properties and cell viability, adhesion and proliferation. Water contact angle of the nanofibers decreased from 126˚ to 83˚by addition of 1 wt % BCNFs. A thermogelling hydrogel based on carboxylated pluronic (Pl-COOH) and gum tragacanth (GT) was fabricated and polymer conjugation was confirmed by FTIR and H-NMR spectroscopy. Morphological and viscoelastic properties of GT-grafted Pl-COOH hydrogels... 

The X-ray attosecond pulses have many useful applications for studying atomic and sub-atomic scales phenomena in attosecond scale duration. Generation and optimization of high-order harmonics is an efficient way to produce such attosecond pulses which are studied in this thesis. There are several limitations in the attosecond pulse generation such as low efficiency of high-order harmonics, long duration of output pulses and the impossibility of producing an attosecond pulse with any desired wavelength in the x-ray region. Therefore, more investigations into high harmonic generation and fully control and optimization of this process is significant. In this thesis, high harmonic generation... 

Productivity is the effective usage of input or resources for production or output. Input (including Energy, raw materials, capital and work force), which is being used for output (including final products or services performed by an organization). Productivity, increases gross domestic product and competitiveness, and improves level of living. Firms and related management levels play the main role in improving productivity. Using productivity cycle management brings the productivity to improve as a permanent process, specifies the rout for productivity and prepares the ground. The most important step in productivity cycle (PDCA) is the measurement of productivity. In this research several... 

Today, the use of carbon nanostructures hybridized with noble metals has attracted considerable attention for the fabrication of bio-electrochemical sensors. Since the specific surface area has an immense effect on the sensing response, three-dimensional structures of graphene have a great capability to utilize in these sensors. In this research, three-dimensional graphene was provided on the porous nickel foam by chemical vapor deposition technique. By evaluation of raman spectroscopy, the time period of 20 minutes for solving of the carbon atoms into the nickel foam was selected as the main parameter of optimized conditions for the synthesis of graphene. Afterward, production of few-layer... 

Nitrite (〖NO〗_2^-) anions are ubiquitous within the physiological, industrial, environmental, and food industries. The potential toxicity risk of these inorganic compounds has well been recognized; thus, the precise detection of these ions by developing reliable and high-throughput analytical methods is crucial for health and environment security. In this study, we present a reagentless electrochemical biosensor using cobalt-based metal-organic frameworks (ZIF-67) and gold nanoparticles (Au NPs) for determination of nitrite ions. The developed biosensor provides the advantages of MOF properties including high surface area, hierarchical porosity, and tunable functionalities along with high... 

In the present study, the factors that affect the IPO underpricing in the Tehran Stock Exchange are investigated. We define the variables of IPO percentage, age and size of companies, dummy variable for rounded IPO prices, market return in a month before the initial public offering, average return of IPOs that had been done during one month before the IPO of each ticker and the dummy variable for industrial group in which the company is located. We had to calculate the initial return of 246 companies that were offered in the years 1380 to 1395. In this study, due to the existence of a daily stock price volatility constraint, a new algorithm was introduced to calculate the dependent... 

Tissue engineering has the potential to revolutionize our health care system. Conceptually, lost or malfunctioning tissues will be replaced by man-made biological substitutes to restore, maintain, or improve function. Tissue engineering has already shown great promise to contribute to treatments of a myriad of diseases including osteoarthritis, cancer, diabetes, skin burns, cardiovascular conditions and various traumatic injuries. Tissue engineering is a highly multidisciplinary discipline that demands integration of knowledge, tools and skills from biology, chemistry, engineering and medicine. Integrating nano- and microtechnologies into clinically sized implants represents a major... 

3D bioprinting is an additive manufacturing method that facilitates the deposition of the desired cells and biomaterials at any pre-defined location. This technique also enables control over the internal structure and external dimensions of printed constructs. Among various biomaterials used as bioinks, the bioinks derived from decellularized extracellular matrixes (dECMs) have attracted significant attention due to their bioactivity and being a rich source of biochemical cues. Here in this study, the decellularized amnion membrane (dAM) has been selected as the main component of the bioink formulation because of its biocompatibility, low immunogenicity, antibacterial property, abundance,... 

Treatment of critical-size bone defects caused by sport injuries, accidents, trauma, infection, and osteoporosis remains a major clinical challenge. In order to repair or regenerate large bone defects, bioactive three-dimensional scaffolds play a key role due to their multilevel porous structure, high surface area, enhanced mass transport and diffusion. Many studies reported that macropore diameters greater than 500 µm can lead to vascularized bone tissue. In this study, a hierarchically porous composite scaffold was prepared. Hierarchically porous silk fibroin- bioactive glass composite and fibroin scaffold were fabricated with controlled architecture and interconnected structure with...