Sharif Digital Repository

Offshore structures are valuable structures used in the offshore petroleum and gas fields for the purpose of hydrocarbon production operation. These structures are influenced by wave loads. Sea waves are inherently alternative and for this reason fatigue failure is considered as one of the most important modes of failure in these structures. Joints in these structures are made by tubes and they are called tubular joints. The joining process in manufacturing of these joints is welding. Welding process induces residual stresses, mostly tensional, in the substructure of materials. This tensional residual stress has a destructive effect on fatigue life of the joint and increases probability of... 

This study aims to investigate the influence of important operational parameters on membrane fouling with the approach of fouling layers and to model these influences in the membrane bioreactor (MBR) for municipal wastewater treatment. At the first phase, 11 operational scenarios were executed using a pilot setup for identifying the system behavior and the optimal scenario. Protein and carbohydrate as the fouling components (SMP) and the transmembrane pressure (TMP) as the fouling criteria were measured in the tests. By studying the influence of operational parameters (sludge retention time (SRT), aeration rate and filtration mode), some useful results obtained for the next phase, including... 

Water shortages resulting from macro-environmental climate changes as well as local inefficient agricultural practices and dam constructions activities have resulted in the gradual reduction of water level in Urmia Lake, located in the northwest of Iran. As such, restoration efforts were initiated to prevent further adverse impacts exacerbating the conditions and creating secondary problems such as regional salt dust generation and dispersion, resulting in health issues for the greater area population in the neighboring vicinities. The utilization of advanced forecast modeling based on deep learning algorithms can assist the authorities to manage better multi-dimensional issues affecting the... 

With the growth of the population and the significant expansion of industries in the last century, many environmental problems have plagued developed and developing countries. One of these environmental problems is water pollution. Observing the effects of water pollution over time, sanitary and industrial wastewater treatment was proposed as a reliable solution. With technology development, wastewater treatment requirements have become stricter. The increase in energy consumption and wastewater treatment costs due to population growth and industrialization on the one hand and strict regulations, on the other hand, have forced those involved in this field to employ a variety of technical and... 

Membrane bioreactors can replace the activated sludge process and the final clarification step in municipal wastewater treatment. The combination of bioreactor and crossflow microfiltration allows for a high chemical oxygen demand (COD) reduction of synthetic wastewater. In this study, experimental data from a laboratory scale membrane bioreactor are presented. In order to investigate the influence of various operating parameters such as hydraulic retention time (HRT), biomass concentration and organic loading rate on organic pollutant removal, the pilot scale submerged membrane bioreactor (SMBR) with a Polyvinylidene Fluoride (PVDF) hollow fiber membrane module was conducted using synthetic... 

Membrane bioreactors are increasingly being used for treatment of domestic and industrial effluents. A major operational drawback of this system is membrane fouling attributed to soluble microbial products (SMPs). In this study sampling were taken from microbial products on the surface and within the membrane pores and mixed liquir for mass characterization of protein content. Water-washing was used for surface and reversible portion of pore samples. Chemical wash with urea was used for further cleansing of SMPs within the pores. All samples were concentrate by precipitation with ammonium sulfate salt prior to analysis. Total protein content of samples was measured by lowry method. SDS-PAGE... 

The problem of restoring power systems after a complete or partial blackout is as old as the power industry itself. In recent years, due to economic competition and deregulation, power systems are operated closer and closer to their limits. At the same time, power systems have increased in size and complexity. Both factors increase the risk of major power outages. After a blackout, power needs to be restored as quickly and reliably as possible, and consequently, detailed restoration plants are necessary. This thesis concentrates on the initial stages of restoration where load pickup and frequency control problem is identified. The best sequence of load pickup for power plants during power... 

Silver is a resistant metal against the oxidation under normal atmospheric conditions, but it reacts readily with sulfur bearing species in the environment and corrodes. Alloying silver with more noble elements, such as Palladium, is a promising approach for increasing corrosion resistance against the sulfur pollutants. The purpose of this research is to develop a plating bath for deposition of Silver-Palladium alloy with acceptable appearance and higher corrosion resistance than pure silver. For this purpose, a bath based on thiosulfate complexing agent was investigated. In this solution, with a bath containing 10 mM of each cation, deposits with palladium content of 6, 11 and 14 % were... 

High reliability and low power consumption are two crucial requirements of embedded systems. To do this, embedded systems exploit fault-tolerant techniques to keep reliability at a guaranteed level and power management methods to reduce power consumption. However, the inherent redundancy of the fault-tolerant techniques increases the power consumption and, consequently, the system temperature, which leads to an increase in the rate of the aging phenomenon. Power management methods increase the system's lifetime by reducing the system temperature. However, some power management methods (e.g., Dynamic Voltage and Frequency Scaling) increase the fault rate. Recently, heterogeneous multicore... 

Natural disasters such as storms, earthquakes, floods, etc. are among the factors that can damage the elements of the power grid and cause them to leave the grid. The result of these outages will be a widespread power outage, which will create many economic and social problems. Therefore, in recent years, the concept of resiliencey has been introduced in power system studies, which examines the extensive outputs in the network as a result of natural disasters.One way to improve the power system resiliency is to strengthen the network by upgrading existing equipment, installing new equipment, and modifying the operation of the network. Among these, the installation of distributed generation... 

In this research, modal incremental dynamic analysis (MIDA) has been investigated on three-dimensional structures with irregular plans. The MIDA method is an incremental static analysis that considers higher modes of the structure. In fact, it is a combination of modal pushover (MPO) and incremental dynamic analysis (IDA) methods that incorporate the advantages of both and is much faster than the IDA method. Compared to constant analyses, incremental analysis is more extensive in terms of results and response to earthquakes. Due to the uncertainties in the nature of future earthquakes, engineers use the IDA method to achieve a broader view of the structure's response under potential... 

The process of human populations growth, limited resources of fossil fuels and its environmental consequences have driven the international community to Renewable Energy. Microbial fuel cell (MFC) has ability of simultaneous wastewater treatment and electricity generation (Energy). This technology can be considered as one of the proposed solutions to reduce costs of wastewater treatment and power generation. Separators are one of the major components of the MFC that have direct impact on cell performance. On the other hand, high costs of the conventional types have caused to limiting development of the MFC in the last decade.
In this study, inexpensive and available glass wool membrane...