Sharif Digital Repository

Due to the expansion of Data Networks and the ubiquity of high speed Internet, new services especially multimedia services have become more popular. Video streaming is one such service, but video data are quite bulky and need to be compressed for transmission since the network has limited bandwidth. This compression is achieved through a video encoder, such as H.264, which is currently the most advanced video encoder. In addition, the network introduces lag in the form of packet loss, delay and jitter which adversely affect real-time video applications.
In this thesis, we try to answer the following question in the context of a video streaming application: what encoding parameters should... 

Drying is one of the important downstream processes in the production of biotechnological products. The dryer design for heat-sensitive materials such as proteins requires special process considerations. In this study, a rotary dryer evaluated for drying protein products. The used liquid enzyme as model, a bacterial α-amylase, first, immobilized on sodium sulfate and sodium tripolyphosphate as carriers in a spraying mode and then, the obtained wet solid materials containing the enzyme, dried in a batch dryer. The performance of this dryer investigated to achieve suitable properties such as the enzyme activity and the final moisture content of product by changing the process conditions.... 

In the world today, biological materials widely used are which requires proper packaging, the types of enzymes are used in various industries: food, pharmaceutical, cosmetics. Shelf Life of enzymes Limited and affected by internal and external factors a maximum of one year. Internal factors include water activity, pH, microbial flora, oxidation-reduction potential, chemistry and biochemistry products, product formulation, additives and the reaction with package. External factors such as relative humidity, light, gas atmosphere within the package, the storage conditions and temperature. Water activity and relative humidity are important factors in spoilage. Avoid drying, lipid reaction,... 

In biotechnology processes, in addition of culture media there is a solid phase which dispensed across the system.In most of bioprocesses, first operational unit for downstream treatment is the separation of this particles from fermentation liquor. In contrast with other categories like inorganic chemistry, solid particles in fermentation liquor (which the main part of it is biomass itself) have complicated physical & rheological properties. For example, all of biomass species are hydrophilic and sometimes form colloidal solutions.With this perspective, separation of solid phase from fermentation liquor is a hard challenge in this kind of processes.In this research, with regard of great... 

The outbreak of a type of corona virus in 2019, plunged the world into a huge panic. Businesses entered into an unprecedented recession and economic growth was severely reduced. Millions of people have been infected and unfortunately countless numbers have also lost their lives. This which quickly crossed the borders of countries, proved how much a not-so-deadly infectious disease can affect human life. Another point that was revealed was the importance of epidemiology knowledge. Since the beginning of the outbreak of this disease, scientists in this field have tried to predict the state of the disease in the coming days by presenting models. Many countries formed special working groups to... 

In this project, quantification of sulfide ion was investigated based on peroxidase enzyme inhibition. The fungal peroxidase was obtained from the liquid culture of Coprinus cinereus NBRC 30628. Two different biosensing systems were suggested for sulfide ion measurement: (1) An amperometric inhibition peroxidase biosensor proposed for determination of sulfide by in situ bulk polymerization of acrylamide for immobilization of peroxidase on screen-printed carbon electrode. Measurements were performed using phosphate buffer solution as a supporting electrolyte in the presence of hydroquinone as a mediator. Identification method was based on reduction of generation current, caused by hydrolysis... 

Electrocoagulation is one of the new methods for water and wastewater treatment that is carried out by electrical current. This method is easily applicable to a variety of wastewater. it is highly efficient in organic matter removal and other toxic are and dangerous pollutants.
This study dealt with diesel and COD removal by Electrocoagulation method. Energy consumption, electricity consumption, and the amount of sludge produced by this method was evaluated. Experiments were conducted in a 2 L reactor, consisting aluminum and iron electrodes.The distance between anode and cathode was 5 cm. To evaluate the efficiency of electrocoagulation method, parameters including: pH, time,... 

One of the most important unit operations in the production of dry powder biological products involves a freeze dryer apparatus. In this process, Liqueur, which is containing the α-amylase enzyme, undergoes a frigidity condition in which loses its moisture during sublimation. Under these circumstances, applying an adequate supply of sublimation enthalpy without raising the temperature of the frigid material up to melting, plays an important role in the quality of the product and preventing degradation of the α-amylase enzyme. Freeze drying depends on two main factors; time and energy. Furthermore, it is necessary to obtain an optimal temperature and pressure for different steps and... 

Lipases (Triacyl Glycerol Acyl Hydrolase, EC.3.1.1.3) are multidimensional biocatalysts which have many applications in food industrials, dairy, fats and oils processing, detergents, synthesis of pure chemical and pharmaceutical materials, paper industrial and cosmetics. Generally, industrial enzymes are produced extracellularly, so their separation from a low-cost complex medium (usually used for production) is one of the cost stages in their production process. Filtration is the most economical method of separation in the production of enzymes, but due to the small size of colloidal particles and cell masses present in the fermentation environment, its use is subject to limitations. In... 

The effects of biosurfactants on sandstone rocks are known in the literature. However, there are few examples of experimental works in Iranian carbonate reservoirs dealing with the effects of biosurfactants under reservoir conditions. This thesis discusses the effect of an efficient biosurfactant produced from Pseudomonas aeroginosa MRo1, a bacterial strain isolated from oil excavation areas in southern Iran, on the recovery of residual oil trapped within carbonate rocks was investigated. The MRO1 could reduce surface tension from 72 to 28 dyne/cm. It also could reduce Interfacial tension from 18.382 to 5.646 dyne/cm.
In a core holder set-up bearing four limestone- and... 

Evidently, environment contamination by water insoluble chemicals present at the industrial wastes could bring about catastrophic consequences to the biosphere. Biological based cleaning technologies are commonly considered as a practical remedy to remove these contaminations. In fact, these techniques are founded on the ability of certain microorganisms to degrade the contaminants. It is crystal clear that the availability of contaminants to the microorganisms is an essential parameter determining the final efficiency of the biodegradation process. In practice, the limited solubility of the contaminants in the aqueous phase leads to mass transfer constraints which consequently, decrease the... 

Determining the best location for new wells is a complex problem that depends on reservoir and fluid properties, well and surface equipment specifications, and economic criteria. Various approaches have been proposed for this problem. Among those, direct optimization using the simulator as the evaluation function, although accurate, is in most cases infeasible due to the number of simulations required. This study proposes a hybrid optimization technique (HGA) based on the genetic algorithm (GA) with helper functions based on the polytope algorithm and the neural network. Hybridization of the GA with these helper methods introduces hill-climbing into the stochastic search and also makes use... 

Polysulfone (PSU) and polyethersulfone (PES) porous membranes; and mixed polymers (PSU and PES) with nanoparticles TiO2, were prepared for air humidification. The mechanical properties and morphology of these membranes were studied by Tensile Tester and SEM/EDX. The effects of membrane composition and operating factors on humidifier performance were investigated. The results revealed that the membrane composition and its structure have significant effect on humidification. The porous membranes with finger type cavities had higher humidification performance but lower mechanical properties. The Membranes which were prepared from polysulfone polymer, 10 wt % of polymers in casting solution and... 

Recently separation technology has been developed and engineers are trying to find more rapid and more economic ways in order to reach pure materials. One of the most important needs of human being is natural gas which has some impurities. Acid gases such as carbon dioxide and hydrogen sulfide must be separated from methane. This operation is called gas sweetening. Membrane contactors are equipments recently developed and may be used instead of packed towers for gas sweetening in the future. In this project we designed and made a membrane contacting unit to separate carbon dioxide and hydrogen sulfide from methane. This unit lets you to study the effect of many parameters such as gas and... 

In this work, bioleaching was used to extract valuable uranium from a low grade ore. Bioleaching experiments were carried out in batch cultures using a native strain of Acidithiobacillus ferrooxidans. Experiments were conducted to investigate the effects of rotation speed, initial redox potential, initially added Fe concentration, particle size, pH, temperature, pulp density, and culture type. In the shake flask systems, over 99% of the uranium was bioleached in 48 hours at some conditions. Uninoculated flasks gave only around 25% leaching. At each study, uranium and iron concentrations, solution oxidation– reduction potential and pH were measured. The results showed that 150 rpm, d80=100 ... 

In this research, an amperometric inhibition biosensor for the detection of cyanide has been fabricated by immobilization of the horseradish peroxidase (HRP) on the surface of glassy carbone electrode (GCE). Chitosan/acrylamide was applied for immobilization of HRP on the working electrode. All electrochemical measurement were carried out with three electrode: Ag/AgCl electrode as reference electrode, GCE as working electrode and platinium electrode as counter electrode which immersed in phosphate buffer solution. The amperometric measurement was done at an applied potential of -100 mV versus Ag/AgCl with a scan rate of 100 mV in the presence of hydroquinone as electron mediator and... 

The main objective of this project is the deposition of photo-catalysts on cement and concrete blocks with an emphasis on commercialization. We started with an extensive study of common methods introduced in previous literature, and conclude with a number of suggestions for industrialization. First, slurry and sol-gel deposition of the photo-catalysts on blocks of type 2 commercial cement which is one of the most used materials in construction of buildings and waste-water treatment plants has been examined to reach a method of sample formation. Due to the simplicity of common methods and low quality of formed samples (less than 5 percent aging efficiency), the obtained experience was used to... 

Presence of heavy metals in industrial waste has always been a serious environmental problem. One of such metals in uranium that is used in important industries such as nuclear industry. Thus, it must be excluded from industrial waste efficiently. This research aimed to study effect of local strain of aspergillus niger in bioabsoprtion of uranium from industrial waste in which good absorption was reached and absorption of local strain was compared with that of control strain obtained from PTCC. Also, local strain was collected from uranium anomalies of Bandar Abbas Mining Site and was used to identify it with reference strains available at NCBI site using PCR and proliferation of part of... 

Penicillin G Acylase is the key enzyme in producing semi-synthetic antibiotics such as Ampicillin and Amoxicillin. In this study, we used E.coli ATCC 11105 in order to produce it. This enzyme was an intracellular one which was produced under suitable conditions. Crude enzyme was released after cell disruption by ultrasonic waves (sonication method) and was partially purified by ammonium sulphate precipitation. Immobilization is investigated at different pHs around the iso-electric pH of Penicillin G Asylase enzyme. Therefore, optimum pH and optimum concentration of ammonium sulphate cuts were determined. Also immobilization process of this enzyme was studied on chitosan polymer, activated by...