Sharif Digital Repository

Mobile Broadband Wireless Access technologies provide mobile users with broadband services, for example music downloading, online games and etc. IEEE 802.20 standard is one of the Mobile Broadband Wireless Access technologies , which has been published to support mobile users with high vehicular speed up to 250(km/h). The issue studied in this research is enhancement of MAC layer in IEEE 802.20 standard.
By having this intention in mind we firstly developed a simulator for IEEE 802.20 MAC layer implementation , then we tried implementing 3 different approaches for connecting mobile users to a new network in order to analyze their performance. Then we provided a method for decreasing... 

Chemical industries are associated with hazardous chemicals and extreme operating conditions. Unsafe events can incur dramatic costs in terms of the loss of life, financial penalties and damages to the environment. Therefore, design of industrial processes which can be operated safely over a wide range of operating conditions is vital. Nevertheless, operation of industrial processes is a strong function of their design. If the process is initially poorly designed, ensuring its safe operation, if not impossible, would require costly modifications at the operational phases. This observation is due to the fact that process design decisions (e.g. design of process equipment) often have a... 

Genetic significant dose to the Iranian population from diagnostic radiology procedures has been measured. A survey of 26500 radiology patients has radiological tests, age and sex distribution. A second survey has produced the radiological operational parameters, including kV, mAs, FTD, field size, filtration, film number & body orientation. Statistical demographic data have been obtained and from which child expectancy number have been calculated. A Rando phantom has been used for dosimetry phase of the gonad doses using TLD. Combining all of the above data a new GSD of 10.5 mrem/year has been calculated which is 14% higher than the previous number measured in 1980  

Wireless Body Area Network (WBAN) is a set of various physiological sensors for remote monitoring and controlling of the patient’s health status. Detection of anomalies, containing faults and physiological stresses, and distinguishing between them can eliminate the need for constant presence of specialists and decrease the occurrence of False Alarm Rate (FAR).A supervisory hardware platform for WBAN architecture is introduced and implemented in this thesis. The proposed architecture contains three sensors for recording of biomedical signals, heart rate, SpO2 and body temperature simultaneously and transmitting them to central node wirelessly through Wi-Fi standard. This proposed architecture... 

Medical ultrasound imaging is one of the common imaging methods in modern medicine, which is used to diagnose and even treat some diseases due to its cheapness and harmlessness. Medical ultrasound transducer arrays have a significant error rate. They are a major cause of failure in ultrasound imaging systems. This problem causes a noticeable decrease in the quality of the images and medical misdiagnoses. The topics of accurate detection of the location and severity of the error or failure, as well as the compensation for weak transducers by signal processing methods, have received less attention from predecessor researchers. In this thesis, an innovative method for accurate error detection... 

The purpose of this project is to design and build a motorized walker with sit to stand ability, by means of which the user can get up from a chair or the edge of the bed and stand with complete independence; Relying on it, the patient could walk easily and finally sit down on the chair, the edge of the bed, or the toilet seat. For this purpose, the conducted researches and previously built devices were studied and the strengths and weaknesses of each were examined. The stages of conceptual design including the design of the sit to stand mechanism, the design of the structure and finally the control algorithm were completed, then the detailed design of the mentioned topics was carried out.... 

Textile industry wastewaters are one of the important sources of environmental contamination because they produce large quantities of highly colored effluents. In recent years, use of advanced oxidation processes by producing highly active and reactive components such as hydroxyl radicals has been proposed. In this study, two oxygenated photocatalytic systems including UV/ZnO and UV/TiO2 were examined for degradation of C.I. reactive orange 16 dye as a typical organic pollutant in textile effluents. A thin gap annular photoreactor was designed and applied for the experiments. The photoreactor provided large surface area exposed to UV light, where in the solution layer renewal on the UV... 

The first study of the present research aims to the possibility of developing simple, accurate and selective potentiometric sensors for the detection of scandium ions in aqueous solution, which is done for the first time. In this study, a sensor array consisting of 17 miniaturized potentiometric sensors based on polymeric membranes containing various ion-extracting ligands were designed and fabricated. Ligands as the active component of the membranes included phosphine oxides and diamides of various organic acids, which were used in the extraction of rare earth metal ions. The possibility of using these extractants in the polymer matrix of membranes for the development of scandium-sensitive...