Sharif Digital Repository

In the current situation and considering the economic conditions, entrepreneurship and self-employment are important factors of business growth. To prepare people in this field, there is a need for effective training that can motivate people. Identifying the effective methods and different dimensions of the entrepreneurship education framework that can lead to setting up a successful program for training people and facilitate the way to achieve the goal of education is one of the important goals of this research. By studying the literature from 2010 onwards, this research systematically examined 96 articles and tried to improve the framework of entrepreneurship education that was stated in... 

Considering the widespread applications of amides, synthesis of these compounds is of great importance. The one pot oxidative addition of amines to aldehydes is one of the most simple and appealing approaches to synthesis amides. With the aim of developing a mild and convenient approach towards preparation of amides, numerous methods have been reported for this important process over the past few decades. These improvements have been mostly related to the optimization of reaction conditions and the use of more challenging substrates including diverse derivatives of aldehydes, and also design a novel and effective catalytic systems. Due to the various advantages of supported heterogeneous... 

Research on the characteristics of the near field earthquakes has been very popular in recent years due to the considerable damages they have caused to the structures located within the vicinity of seismic sources. The incapability of response spectra for structural damage assessment has been revealed through recent investigations. The recorded data show that the near field earthquakes are often accompanied by a large energy pulse in the beginning of the records caused by the so-called directivity phenomenon. That has encouraged many researchers to study the possibility of using the velocity pulse of these records to evaluate the imposed seismic demands on structures. Thus, investigating the... 

Considering the widespread applications of α-aminonitriles, their synthesis is of great importance. The Strecker reaction represents a direct and appealing approach for the preparation of α-aminonitriles. With the aim of developing a mild and convenient approach towards the construction of α-aminonitriles, numerous methods have been reported for this important process over the past few decades. These have been mostly related to the optimization of reaction conditions and the use of more challenging substrates including ketimines and ketiminium salts and design of novel and effective catalytic systems. Due to the various advantages of supported heterogeneous catalysts and in our aim to... 

Financial and monetary markets are appropriate areas of applying Chaos Theory. Firstly, current theories of financial and monetary economics state that economic and financial variables such as exchange rates and stock prices are stochastic, so forecasting them is almost impossible. Secondly, if we find the hidden ordered and deterministic trends, we can achieve considerable profits. In this piece of research, we evaluate different methods and tests of detecting chaos in financial time series, and choose the most applicable methods to test financial markets’ indices. The main three indices of Tehran Stock Exchange, including Price, Finance and Industry indices, are examined. A sample of the... 

The issue of automation has always been a concern for humans over the years. Replacing humans with machines or intelligent software to perform various tasks can significantly improve the accuracy and speed of those activities. One of the long-standing aspirations of humanity has been the automation of driving. In addition to freeing individuals from the time-consuming task of driving, automating vehicles can also dramatically reduce road accidents. To achieve this goal, vehicles need to be equipped with various sensors such as radar, cameras, lidar, and more. Each of these sensors has its advantages and disadvantages, and as a result, all of them must be used for safe driving. In this... 

Superparamagnetic core/shell nonporous (S1) and core/shell/shell mesoporous (S2 and S3) nanocomposite magnetite/silica particles with a magnetite cluster core of 130±30 nm, a nonporous silica shell of 90±10 nm thickness, and a mesoporous silica shell of 70±15 nm thickness were prepared thorough a simple method. Mesoporous particles were prepared with two BJH pore sizes (2.44 for S2 and 3.76 nm for S3 particles, respectively). The fabricated S1, S2 and S3 particles present high saturation magnetization values of 20, 13 and 17 emu/g, respectively. As a biological application, the lipase from Pseudomonas cepacia was successfully immobilized onto the amino-functionalized nanocomposite particles... 

In this project a knee prostheses wear testing simulator based on a parallel mechanism for applying forces and torques, is designed. First according to ISO 14243 standard required degrees of freedom and design constraints are determined and also regarding simulator requirements some considerations in design are outlined. Considering all of these parameters, literature has been searched for proper parallel mechanism and because no suitable parallel mechanism, which is a 3 DoF 2T1R paralle mechanism with rotational degree about z axis, has been found; several new designs of proper mechanism have been presented. Scoring different mechanisms according to outcomed parameters from standard and... 

Fighting contagious microbial diseases is considered a serious health issue, which has attracted much attention in worldwide. Thus, development of new materials based on nanostructures as a new generation of antibiotics to address this challenge has been of interest to researchers in recent years. Nanostructures based on metallic oxide semiconductors such as oxides with light absorption, production of electron-hole pairs in needle like structures cause tearing bacterial membrane and eventually destroy the bacterium. To this end, we designed experiments to study mechanism and physics governing the process of bacterial degradation to determine the best conditions for inhibiting bacteria... 

Oscillators are an important building block in the design of synthesizers for RF system applications. State-of-the-art operation defines that an oscillator should have the best spectral purity while consuming a low amount of power. In recent years, several methods have been presented for reducing phase noise separately in the 1/f2 and 1/f3 regions. As CMOS technology advances, the amount of power supplies decreases, which worsens the inherent flicker noise. In this thesis, it has been tried, while investigating the existing methods in the phase noise in this region, it presents the proposed oscillator which is based on a three-coupled transformer. This voltage bias oscillator operates at a... 

Approximately 1.36 billion people worldwide suffer from sleep apnea, necessitating accurate diagnosis and treatment. Traditional sleep clinics rely on Polysomnography (PSG)-based monitoring devices. However, these devices are not only voluminous but also prohibitively expensive, requiring numerous sensors and wires that disrupt sleep and cause discomfort for patients. To address these challenges, we have developed a wireless wearable system. This system comprises three sensor blocks, each capable of capturing vital signs from the body, resulting in a total of eight signals. The first two sensor blocks capture signals from the body, which are subsequently modulated and transmitted to a user's... 

The continuous growth of network traffic and people's demand for higher data rates, have driven wireline communication systems towards higher data rates. In these systems, the power consumption of these transmitters and receivers is a crucial and influential factor. This paper presents two different solutions to reduce the power consumption and area of these systems. In the first solution, a low-power phase shifter with variable phase and amplitude control is introduced. The changes in these parameters are mutually orthogonal, ensuring that a change in one characteristic does not affect the others. This phase shifter can be used to generate clock pulses with different phases in wireline...