Sharif Digital Repository

Today, position sensors are inseparable parts of engineering systems. Encoders and resolvers are the most common types of position sensors that are widely used in industries. Due to low price and high accuracy, encoders are the first choice of engineers. Yet, their performance deteriorates under harsh conditions, namely wide temperature range operation, intense vibration and polluted environments. On the contrary, resolvers are rigid and robust which make them resistant to polluted environments.According to principle of operation, resolvers are divided to two main types: variable reluctance (VR) and wound-rotor (WR). Researches has shown that wound rotor resolvers have better performance... 

Recently, there has been an increasing trend towards the use of millimeter-wave (MMW) imaging in various detection applications. This is mainly due to two factors: first, the radiation in the MMW band (30–300 GHz) is nonionizing and safe to use and second, it is able to penetrate through most dielectric materials as well as poor weather conditions, such as smoke and fog. With these potentials, MMW imaging has been used in a variety of applications, including target surveillance and precision target imaging, safe aircraft landing, highway traffic monitoring in fog, remote sensing for civil applications and concealed threat object detection for security concerns. Moreover, it can also find... 

In this thesis the hourly concentration of different gaseous air pollutants in Tehran is modeled using Land Use Regression (LUR) and Artificial Neural Network, separately. Both models are provided with the same set of input data; the first step is to find these data. Since traffic affects air pollution, information about traffic conditions is one of the main inputs in air pollution modeling. Therefore, to obtain traffic information, in this thesis, first a novel method is developed to extract and analyze Google Maps traffic data. In this method, image processing is used along with the Geographic Information System (GIS) to count the number of pixels of different traffic colors for each road... 

Thermomechanical processing during hot rolling and subsequent annealing of rolled sheets are one of the procedures for improving the tensile and formability properties of metals and alloys. In this regard temperature and reduction in area are the most important variables governing the behavior of 304 L austenitic stainless steel during the hot rolling process. The aim of this research was to investigate the effect of rolling temperature and subsequent annealing on 304L steel in order to achieve a microstructure with favorable mechanical properties and bimodal grain size. For this purpose, the rolling process at temperatures of -50, 25, 200, 400, 600, 800 and 900 °C using different thickness... 

Nowadays, with the increasing need of various industries and applications to directly create linear motion, linear resolvers are attracting more attention than ever. Achieving high accuracy as well as measuring absolute position leads to the introduction of a new generation of resolvers, called multi-turn resolvers. Usually, a multi-turn resolver consisted of two individual resolvers in one frame, while using a common core for both resolvers can help to make the multi-turn sensor smaller, cheaper, and lighter. Nevertheless, the studies conducted on linear and multi-turn resolvers are very limited. Therefore, this research proposes an integrated core linear variable reluctance multi-turn... 

Today, the “wireless” is used almost synonymously with radio-frequency (RF) technologies as a result of the wide-scale deployment and utilization of wireless RF devices and systems. The RF band ranges from 300 kHz to 300 GHz and its use is regulated by regional and international agencies. With the ever-growing popularity of data-heavy wireless communications, wireless products and services, the demand for RF spectrum is outstripping supply, which causes the spectrum congestion. Therefore, the time has come to seriously consider other viable options for wireless communication using the upper parts of the electromagnetic spectrum. In this way, the optical band which includes infrared, visible,... 

This thesis presents significant findings relevant to the transportation industry, focusing on the factors influencing drivers' inclination towards seeking higher payment. The study also proposes potential strategies to enhance driver satisfaction and retention. The research examines the elements that affect drivers' inclination to request higher wages when confronted with challenging work scenarios. Data from Iranian heavy vehicle drivers were collected using a structured questionnaire, which assessed their willingness to receive higher wages under unfavorable conditions such as mountain roads, hot and muddy weather, additional stops during the trip, and extended periods away from home. The... 

Computerized tomography (CT) is a powerful tool among existing bioimaging techniques for capturing bio-images. In fact, CT imaging systems have attracted great attention in the last decades, because of their fast and high-quality reconstruction, low complexity and low-cost hardware solutions. In a CT scan procedure, linear sensors receive x-ray radiations, passed through the patient’s body and The quality of the reconstructed image is essentially influenced by the number of captured line projections. Nevertheless, gathering the adequate amount of data requires the patient to being exposed to X-ray radiations for a long time. However, the intensification of x-ray radiations could lead to... 

In this research, two novel optical methods have been proposed for DNA local sequence alignment. The proposed methods benefit from algorithms and methods in computer field and ability of parallelism in optical wave to achieve a low-cost process and propose an easy understanding output in DNA local sequence alignment procedure. The first method is built upon moiré matching technique which is extended by proposed HAPPOC scheme using amplitude, phase, and polarization of optical wave. For analyzing the extended moiré output, a novel 3D Artificial Neural Network is designed and developed by optical structure. The second structure, as named HAWPOD method, is based on DV-Curve method. The HAWPOD... 

Procurement field and supplier’s selection are key decisions in the supply chain in today's business environment.In this problem, both procurement and transportation costs are important. The Traveling Purchasing Problem (TPP) belongs to this field of study. In spite of many researches in the TPP, most of the researches are confined to one single purchaser. In this research, a new variant of Traveling Purchaser Problem is proposed with priority in purchasing. The priority policy is assumed for every single of products and the purchasers’ objective is to meet all of the demands according to their priority and vehicle's capacity in the lowest cost. In this regard, the purchaser has to buy the... 

Today, presence of micropollutants, including pharmaceutical compounds, in aquatic systems has turned into a major environmental challenge threatening the health of humans and many aquatic and terrestrial organisms. In the recent years, biodegradation of pharmaceuticals using enzymes, such as laccase, has been presented as a green method for eliminating these types of pollutants. Furthermore, regarding the improved stability and reusability of immobilized enzymes, these types of biocatalysts are suitable for industrial applications. Enzymatic membrane reactor is a promising method of enzymatic treatment and fabrication of a high-efficiency enzymatic membrane is a major step to begin this... 

Nowadays, millimeter-wave imaging is widely used in security and medical applications. The growing threat from terrorist attacks is driven research on novel ways to enhance security inspection systems. Millimeter-wave imaging not only is an effective option of penetrating into dielectric materials including cloth, but also provides suitable imaging resolution. Moreover, millimeter-wave imaging is capable of identifying different materials making it a promising option for concealed weapon detection. In spite of X-ray, millimeter-wave imaging is non-ionizing, allowing for non-invasive imaging. In this thesis, first we investigate different millimeter-wave imaging systems and reconstruction... 

One of the most important alternative technologies in the field of security monitoring is millimeter-wave imaging technology, which is a good alternative both for performance and cost-effectiveness. Conventional security monitoring techniques use optical images or metal detectors to control people in crowded, sensitive places, but with the help of electromagnetic waves, these technologies can be obtained. This way, metal and non-metallic objects hidden inside clothing, bags or shoes can also be detected that are not identifiable by conventional security-control methods. This thesis examines the implementation of an improved algorithm for automatic detection of objects in millimeter-wave... 

Terahertz (THz) spectroscopy has recently attracted great interest due to the special characteristics of THz waves, such as their capability of penetrating and passing through many non-polar materials, non-ionizing atoms and especially human tissues, and less scattering compared to optical waves and X rays. Also, polar molecules of some dielectric materials have vibrational or circular oscillations that create peaks in their spectral characteristics. This can be used to identify materials by spectroscopy. In this thesis, a simple THz spectroscopy system is introduced and modeled for detecting the C-4 material. First, a wideband Vivaldi antenna is designed and simulated for the frequency... 

One of the major environmental problems in recent years is the presence of micropollutants that cause many problems for the environment and living organisms. The micropollutant bisphenol A and the drug diclofenac are one of the pollutants and endocrine disruptors. Usually, conventional biological and physico-chemical methods do not have a high ability to remove such pollutants. Also, advanced oxidation methods usually lead to the production of highly toxic products. Using enzymes is an attractive method to remove these micropollutants. Laccase enzyme is one of the most famous enzymes in the field of biotherapy because it can remove a wider range of pollutants and it is one of the... 

Food spoilage cased by food-borne pathogens and microorganisms is a serious problem in the food and packaging industry. Then, the demand for antibacterial agents in food packaging is growing. The antibacterial efficacy of some nanocomposites has been recognized and exploited in various industries, including the packaging industry. Also, metal organic frameworks due to their porous structure, are used in various fields such as food packaging. The purpose of this work, is synthesize hybrid nanocomposite that have promising antibacterial activity for preparation of food packaging films. Carboxymethyl cellulose is a derivative of cellulose fiber. The use of carboxymethyl cellulose as... 

Increasing advances in millimeter-wave imaging have given the new technology a special place in military and civilian activities. A very important advantage of this imaging system, which has led to its rapid development and growth, is that unlike methods such as X-ray imaging, the millimeter-wave signal is completely harmless to the human body. Because millimeter-wave imaging is non-ionizing, allowing for non- invasive imaging. Also, the millimeter-wave easily passes through human clothing and is reflected when it hits the human body, metal and ceramic objects, and some other objects. As a result, it can be used to photograph underwear, insensitive and safe places such as airports. In this... 

Nowadays, micropollutants present in aquatic environments posses a significant threat to the well-being and health of human beings. Various physicochemical and advanced approaches have been proposed to confront these hazards. In recent years, biological treatment methods have gained great interest for their green approach. One of these biological treatment options is the treatment of polluted waters by enzymes. Enzymatic treatment of micropollutants can be achieved by oxidoreductase enzymes. One of the most important and widely used oxidoreductase enzymes employed for water treatment is Laccase. However, enzyme immobilization is employed to counter the drawbacks of using enzymes, such as...