Sharif Digital Repository

Polyamide-6 is a thermoplastic polymer that is classified as electrically non-conductive materials. One way of adding conductivity to the polymer matrices is by utilizing them in a nanocomposite form. Superior mechanical and electrical properties of Carbon Nanotubes make them worthy of being chosen as reinforcement in nanocomposites to extend their operation to a broader range of applications, like conductive nanocomposites, mainly polymer-based matrices. The Nanotubes have chemical affinity and tend to entangle and aggregate. Because of this, to achieve a uniform and remarkable electrical conductivity is hard-to-reach. state of entanglement effects correctly melt methods of polymer blend... 

In order to increase the service life and prevent the breakdown of apparatuses, instalations and equipments, we are in a position to maintain them. In this regard, there are three methods for maintenance of machineries, which are called reaction maintenance, preventive maintenance and predictive maintenance. By carrying out a predictive method or monitoring the situation, it is possible to know the health of the machine and take the necessary measures before the damages occurs. Vibration analysis, temperature analysis, oil analysis and flow analysis can be used for monitoring the situation. Reciprocating compressors are one of the most costly repair equipment that needs to be monitored... 

In this report the important factors affecting the levitation melting of copper are discussed. Pure copper nanoparticles were synthesized by utilizing an Electromagnetic Levitation Melting Gas Condensation (ELM-GC) method. Pure bulk copper samples were melted and evaporated by electromagnetic levitation technique in an inert gas atmosphere in a silica tube. Copper nanoparticles were formed from ascending vapor by employing high purity argon and helium as carrier gases and cooling agents. The pressure of inert gas was changed in both helium and argon atmospheres to investigate on pressure’s effect. Particle size and morphology of the produced nanoparticles were studied by Field Emission... 

The present survey study aims at investigating and comparing risk indices in highway and freeway projects implemented through Build-Operate-Transfer (BOT) and Design-Bid-Build (DBB) delivery methods. In this regard, two distinct questionnaires were developed (one for BOT and one for DBB delivery method) and interviews were conducted, too. The questionnaires were, then, sent to the target population, i.e. all the experts and agents involved in highway and freeway construction projects implemented through either BOT or DBB method. The collected data were then submitted to Statistical Package for Social Sciences (SPSS), version 22.00, to be analyzed. The results showed that risks had generally... 

The purpose of this thesis is to introduce and review a recent methods in simultaneous hypothesis testing. False discovery rates, Benjamini and Hochberg’s FDR Control Algorithm, is the great success story of the new methodology. Much of what follows is an attempt to explain that success in empirical Bayes terms.The later chapters are at pains to show the limitations of current largescale statistical practice: Which cases should be combined in a single analysis? How do we account for notions of relevance between cases? What is the correct null hypothesis? How do we handle correlations? Some helpful theory is provided in answer, but much of the argumentation is by example, with graphs and... 

Nowadays the popularity of renewable energy is increasing due to its clean and inexhaustible nature. Also, if the local potential of each area is used, there is no cost to connect to electricity network. But these energies have low reliability due to their oscillating nature. To solve this problem, it is proposed to use systems based on several sources of energy called hybrid systems. In this research, a mathematical model is proposed to design a renewable hybrid system that minimizes the present value of costs while maximizing system’s reliability. To consider the uncertainty in the solar radiation data and energy demand, Bertsimas’s robust model is applied to our model. In which variables... 

As the fourth most common neurological disorder, epilepsy affects lots of people all around the world, some of whom have to live with unpredictable seizures uncontrollable by surgery or medication. Hence, Developing systems for detection and prediction of the epileptic seizures will help the patients to avoid the possible damages caused by sudden seizures. This study addresses the task of epileptic seizure prediction, using three different novel approaches. The first approach, which is based on anomaly detection, contains three steps: feature extraction from EEG signals, training a one-class SVM classifier, and a post-processing step. The second method exploits a recurrent neural network to... 

One of the basic characteristics of Wireless Sensor Networks is their resource limitations. As a result, it is essential to try to decrease costs in such networks. These limitations are more critical in transmitting multimedia data with larger data units. In addition, when transmitting real-time multimedia data, delay is an important factor to consider. According to these limitations, Wireless Multimedia Sensor Networks are congestion prone. In this thesis, a transport layer protocol has been proposed. This protocol consists of three three steps in handling congestion. First, it detects congestion according to the queue length in the node. If the lsength is greater than a minimum threshold,...