Sharif Digital Repository

In local transportation service companies, there is a need for estimation of arrival times (ETA) for customers. These companies not having the sufficient number of active online users, they are not able to obtain a proper estimation for ETA from that data. However, there are some overseas companies that have the established user base, and provide access to necessary data with a service fee. It is possible to solve this problem using the data which they provide.In this thesis, the problem of learning a hidden graph for the purpose of aiding local companies is explained and different aspects of it are introduced. In order to tackle this problem, first we define the idea of vertex separators,... 

In recent years, deep generative models have achieved incredible successes in various fields, including graph generation. Due to the advances made in graph generation by deep generative models, these methods have shown numerous applications from drug discovery and molecular graph generation to modeling social and citation network graphs. Graph generation is an approach to discovering and exploring new graph structures and has been attracting growing attention. One of the most challenging applications of deep graph generative models is molecular graph generation since it requires not only generating chemically valid molecular structures but also optimizing their chemical properties in the... 

By Exploiting financial statements, ownership structure, and loan data for nonfinancial Iranian listed firms from 2007 to 2018, we investigate the impact of group structure on connected lending and its’ consequences on the firm investment. The group structure is formed, when a bank directly or indirectly owns one or multiple firms. Fist, our findings show that the vertical bank-firm connection, on average increases the probability and the amount of the loan supply by 2.53% and 78%, respectively. In return, the horizontal connection just increases the probability of the loan supply by 1.55%, and we find no evidence on its’ impact on the amount of the loan supply. Then, we investigate the... 

The rapid adoption of the Internet of Things (IoT) has led to significant advancements in healthcare digitization and modernization. However, given the sensitive nature of medical data, security and privacy of such data have always posed major challenges. Moreover, resource constraints of IoT devices have necessitated the use of cloud resources for handling massive amounts of data in traditional approaches, introducing issues like single points of failure, processing delays, and security vulnerabilities. In this context, blockchain technology shows promise for enhancing security, decentralization, and returning data ownership. A robust solution should maintain confidentiality, enable access... 

Ridge gap waveguide is a new technology with low loss and high power handling capability in millimeter wave(mm-wave) frequencies. In this technology there is no need for electrical connection between the constitutive parts and using dielectric material as a substrate. This thesis focuses on the capabilities of this technology in realization of devices used in communication systems at the mm-wave frequency. Novel devices based on this technology have been designed, fabricated and tested. The main goal of the thesis is realization of the whole RF front end of a communication system in Ka band based on this technology. So at first step, a ridge gap waveguide transmission line is evaluated and a... 

In this research, the effect of organizational Bureaucracy on the integration of technical knowledge and market knowledge in the process of developing new products, along with other factors mentioned in previous literature, has been studied. To this purpose, a questionnaire was prepared which measured both the degree of integrity and the effect of bureaucracy on integrity. This questionnaire was completed by marketing and research and development managers of 39 innovative companies in the field of information and communication technology (ICT). Regression analysis was used for data analysis. The results of this research show that bureaucracy as an organizational factor, along with other... 

Increasing competition in global market and different requirements of customers persuade manufacturers to improve the efficiency of their manufacturing activities. For this end cellular manufacturing systems can be introduced as an innovative and compromising practice for companies. Among the necessary decisions for a successful cellular manufacturing design and implementation, production routing selection (PRS), cell formation (CF), group layout (GL) and group scheduling (GS) are the four most important ones. This research investigates these decisions and proposes a new approach to integrate them. We use important production factors such as production volume, operation sequence, operational... 

Conical nanochannels have desirable electrokinetic properties due to asymmetry,including ionic current rectification and ion selectivity. The present study numerically addressed the effect of slip length on the ionic current rectification and ion selectivity in conical-shaped electrolyte-loaded nanochannels with and without a coated polyelectrolyte layer. The electrolyte was considered a salted incompressible Newtonian fluid. The polyelectrolyte layer was also modeled as a rigid and charged porous solid saturated with a salted Newtonian fluid. The electrolyte-polyelectrolyte layer interface was modeled as a surface, considering ion partitioning with distinct physical properties across the... 

RFID systems are available in various applications for indoor and outdoor positioning. Location awareness in public environment and in stores and companies are widely in use. In indoor environment , multipath and fading changes signals specification, so it is difficult to detect the related parameters. In the other hand the necessity of fast and reliable system which support traffic and a large number of users are in demand. RFID which is based on radio frequency signals is developed for this aim.RFID system with asymmetrical link which support UWB and Narrowband signals is suggested for indoor positioning application. RFID passive tag in this system is redesigned in his thesis.... 

In this work, an analytical model has been proposed for rectifiers used in RFID & WSN applications. Body effect has been considered in this model, as well as the effect of transistor size and number of stages on the output voltage of the rectifier. Using proposed equations for both rectifier circuit and the matching network, the power harvesting system is optimized by means of co-designing the rectifier and the matching network. The results of the proposed model are in good agreement with the simulation results.
Finally, A Rectifier circuit which is designed to generate 1-V dc across a capacitive load is presented. Simulation results show that the sensitivity of this power harvesting... 

Immensity and profundity of mathematical logic have provided an opportunity for its interconnection with other branches of science, one of which is computer science where theory of dependent types and lambda calculus lounges amongst the area of their overlap. The former has been engendered for the sake of deepening the connection between mathematical logic and programming. On the other side, lambda calculus which is a formal system in mathematical logic and computer science, developed as a tool for formal computations, could also be counted as a programming discipline. It is the objective of this thsis to study the two aforementioned fields with emphasis on unification of higher-order... 

Recently, biopolymers such as alginate, cellulose, chitosan, gelatine, starch and wool have been used as supports for catalytic applications. Several interesting features of the biopolymers for example, bio-degradable, environmentally safe, high sorption capacity, physical and chemical versatility make them attractive to use as supports. This study, the four functionalized biopolymer-based composites were designed and synthesized as well as heterogeneous catalysts used in the synthesis of 1,2,3-triazoles, oxidation of alcohol, reduction of nitroarenes and carbon-carbon coupling reactions.A novel cellulose supported copper NHC complex has been prepared by the reaction of cellulose supported... 

Water treatment from industrial and domestic pollutants is one of the most important issues in recent decades. In the present research, simulation of water purification using single-layer graphene membrane were studied. The effects of nanopores diameter, applied pressure, concentration of contaminant ions, and functional groups on the amount of filtered water and ion rejection through the membrane were quantified. Contaminant ions including Na+, K+, Mg2+, Ca2+, and Cl- were dissolved in water. Based on the results, by increasing the pore diameter and applied pressure, more water would pass through the membrane. Also it was concluded that pores with functional groups have better performance... 

Ice formation upon various surfaces could lead to many industry problems and result in unpleasant accidents. For instance, the formation of ice on wind turbine blades or airplanes/helicopter wings could cause catastrophic disasters. The methods used to address this problem usually require exogenous energy consumption or anti-ice ingredients. The energy or anti-ice ingredients usage has adverse environmental effects and should be replaced with better approaches. One of these approaches is utilizing modified anti-ice surfaces. In this method, by modifying surface features, such as physical asperities and surface energy, the icing time of the surface could be prolonged. These surfaces are... 

Using a micro-based general equilibrium model with four sectors, I introduce a context to study the macroeconomic effects of energy subsidies. I calibrate the model using Iranian energy data, estimating elasticities of substitution and energy shares. Using this calibration, I compare the steady-state results of two compensation plans for energy price reform, tax cuts and cash transfer, explaining the active mechanisms in each scenario and investigating their impact on household welfare and production levels. I calculate that the steady-state energy price in Iran is 40% of regional prices, and we simulate the reform in which prices are increased from this price to regional prices. I conclude... 

In this study, we aim to investigate the effects of energy price shocks on macroeconomic variables, particularly inflation. To achieve this goal, we have designed a Dynamic Stochastic General Equilibrium (DSGE) model with nominal rigidities and financial frictions. In this model, households and firms are energy consumers, and the government is the sole supplier of energy, selling it to households, firms, and the external world without energy constraints. The energy price in this model differs between firms and households, and we analyze the almost persistent shocks to both of these prices. Within the framework of this model, we analyze the role of monetary policy in controlling the... 

This research aims to explore the effectiveness of past tariff evolutions in shaping firms' response to current input prices. Additionally, it investigates how asymmetric fuel pricing across different industries influences overall industry efficiency and prosperity. Furthermore, the study examines the impact of fuel subsidies on the equilibrium distribution of companies independent of welfare decline. In Chapter 1, utilizing microdata from Iranian industrial workshops between 1386-1396 (2007-2017) A key finding is that new firms exhibit a significant and stronger reaction to energy price variations compared to other firms when it comes to technology choices.Chapter 2 presents a structural... 

Sight is probably our most important sense. Every day, humans are exposed to many visual stimuli in their surroundings. The human brain is able to identify and prioritize important and valuable stimuli and memorize them. Identifying and remembering these valuable stimuli is vital to meeting the needs and maintaining survival. The aim of the proposed research is to find the effect of reward learning on the coding of visual objects in the human brain. Previous results have shown that long-term reward-object association make valuable objects more recognizable behaviorally. Studies have also shown that visual stimuli and the pattern of activity of primary visual cortex neurons are closely... 

Learning the value of the objects in the living environment of animals has a great significance in guiding the behavior of animals. Therefore, understanding the mechanisms and structures involved in this phenomenon in the brain is one of the topics of interest in modern neuroscience. One of the most important structures known in the mammalian brain that plays an important role in learning the value of objects is the Basal ganglia. The value signal of objects has been observed in different areas of this structure. Another important area of the brain, whose role in learning the value of objects has recently been investigated, is the area of the Ventrolateral Prefrontal Cortex (vlPFC). On the... 

The speed of finding things in humans and animals is essential; Because human is surrounded by many things, but only a tiny number of them are important to them. Animals also need to recognize valuable objects for their survival quickly, but searching for an object surrounded by many other things is a complex and time-consuming task. Therefore, understanding how search operations can increase the speed can be helpful and improve the accuracy and efficiency of common and essential searches in the community, from screening to understanding medical images.Also, the human brain can identify and prioritize valuable stimuli and keep them in mind, so until now, researchers in the field of...