Sharif Digital Repository

In industial applications such as linear accelerators, pulsed lasers, nuclear fusion, radar systems, medical applications and etc. that need great ratio of instantanuse to the average power, pulsed power supplies are used. These power supplies store energy in an energy storage element and discharge this energy to load in a short period of time. The most important characterisitics of them are output pulse quality, reliability and longevity of the resource, efficiency and cost. One of the devices that produce high instantaneous RF power is magnetron tube. In some applications such as radar systems, quality of the output RF is very important and the most important factor that affect the quality... 

Pulsed power supplies are used in linear accelerators, pulsed lasers, nuclear welding, radar, some medical applications, etc. which require much more instantaneous power than average power. These sources store energy in an energy storage element for a relatively long period of time and then release this energy in a short period of time. Among the most important goals pursued in these power supplies are the quality of the output pulse, the reliability and lifetime, efficiency, and cost, which depending on their application, some of these features are more important. One of the important applications of pulsed wave power supplies is their use to power microwave lamps. In some applications of... 

In recent years, chromatographic technique as one of the most important analytical techniques have been developed for the analysis of complex samples. Hyphenated chromatographic techniques such as liquid or gas chromatography combine separation and spectroscopic detection technique to exploit the advantages of both and they have attracted attention of chemists to analyze complex mixtures. However, inadequate separation challenges still exist especially in the analysis of complex samples. Therefore, two-dimensional chromatographic systems such as comprehensive two-dimensional gas chromatography-mass spectrometry (GC×GC-MS) have been proposed for the analysis of complex samples due to their... 

Implementation of various incentive-based demand response strategies has great potential to decrease peak load growth and customer electricity bill cost. Using advanced metering and automatic demand management makes it possible to optimize energy consumption, to reduce grid loss, and to release generation capacities for the sake of providing sustainable electricity supply, and reducing electricity bills for the customers. With these objectives, this thesis examines the previously suggested load scheduling programs in both residential and industrial sectors, and proposes new practical strategies for load management. This thesis has mainly focuses on three subdivisions of load management... 

The main purpose of this thesis is to analyze the total productive maintenance based on computerized maintenance management system. At first, a detailed study on total productive maintenance is performed and then the requirements of this maintenance strategy are specified. Also, a computerized maintenance management system is defined which can help total productive maintenance to reach to its requirements. Finally, a conceptual model and entity-relationship model for computerized maintenance management system data base has been created  

In this thesis, DC transmission of offshore wind farms is studied thoroughly. Various system configurations that are introduced in the literatures are discussed and their control scheme for normal conditions and grid faults are studied. Then, the HVDC transmission based on voltage source converter, located between a local offshore ac grid and the onshore ac system is investigated as the most practical choice. The HVDC linke circuit elements are calculated and the control strategies of the offshore and onshore converters are introduced. DFIGs are considered to be the best choice for the offshore wind turbine generators. Then, the system is simulated and the frequency of the offshore grid is... 

The main aim of this thesis is to develop the technical knowledge of designing and making active ingredients of domestically produced drugs, decreasing the costs, independency in producing these products, and checking outflow of currency. It also aims to reduce the financial challenges of patients who have to pay huge amounts for such drugs. Conducting research in the field of reverse engineering and using its definition, and attempt in made to get knowledge into the stages of product development process, to determine the technical standards associated with each stage, to recognize how knowledge is shared during this process, and to present some methods of establishing the infrastructure... 

Increase in growing concerns over environmental pollution and depletion of fossil fuel resources motivate the need for cleaner energy technologies and stimulate research in facilitating renewable energy systems. In recent years, photovoltaic systems have attracted great attention since they remove the need for energy storage systems and intermediate processess for energy conversion. However, high capital cost, low efficiency and low energy density per area of these systems, as compared with other technologies hinder its industrial use. To surmount these bottlenecks and improve technical performance of PV systems, it is crucial to optimize configuration of convertor connection and to improve... 

One of the main objectives in operating a power system is to maintain the system voltage properly to avoid equipment damage and transfer power efficiently. Automatic control of transmission network voltage provides significant improvements in security, quality and efficiency of power system operation. This thesis investigates coordinated voltage control of power systems in normal, alert and emergency states. The aim is to propose a comprehensive framework for real-time operation of practical power systems, ensuring secure operation of the system in the normal state and after occurrence of sever contingencies.
At the first, a new coordinated voltage control scheme is proposed to ensure... 

Today, organizations are surrounded by basic and continuous changes such as declining organizational resources, reduction of the production cycles, and the need for rapid adaption. Those organizations remain competitive while maintaining their productivity, that have following characteristics: accurately plan and assess their knowledge resources, create and absorb beneficial knowledge, store and organize their knowledge, disseminate knowledge to needed areas, and use knowledge in practice and decision making, to improve their products/services as well as their performance. Therefore, the human capital has been considered as knowledge owners and the most important organizational resource, on... 

Feyarabend’s philosophy of science is against method and rule such that he believes that “anything goes”. However, he sometimes applies the term “progress”. Reviewing his publications shows that from his point of view, progress is qualitative and relative. So, unlike other philosophers of science Feyarabend ignores the clarification of the concept; subsequently, his applications of the term “progress” are somewhat ambiguous. However, by studying his philosophy, one may realize what should be done to achieve progress in any sense. The affirmative aspect of Feyerabend’s philosophy, while highlights the social and ethical elements, considering his humanitarian outlook as well as his special... 

Increasing population and competition for producing various productions and also more consumption in recent decades, result in producing more wastes. Therefore effective and continuous waste management is essential for monitoring the process (from the wastes generation source to the waste disposal) and establishing the efficient strategies to reduce wastes. One of the major sources of waste generation is hospitals that cause lots of environmental problem unless they are managed properly.Recycling is an important element of waste management that can reduce costs by innovative and proper management. The purpose of this research is identification of recyclable plastic items and estimates the... 

Lack of financial sources for production and performing projects has been an effective issue in all governmental and non-governmental organizations. So, using a structure with capability of detecting and forecasting all expenses and costs, and being able to convert the mass of data into useful and instrumental reports for managerial decision such as estimating total cost, selecting the syntax of production and etc is obvious for recourse management of every organization. Among the various components of the cost engineering system, cost management system by recording and allocating cost is an important issue in efficiency of every cost engineering system.In this thesis, Automotive Industrial...