Sharif Digital Repository

This Thesis aim to study the evolution of knowledge network in the path of innovation capability accumulation in knowledge-based firms, active in Iran's innovation system as a sanctioned economy. The research, by an in-depth case study and at the micro level, examines the accumulation of capabilities and the evolution of the knowledge networks for two knowledge-based firms active in the manufacture of linear accelerators and cargo-scanners as high-tech products. The results show that 1) the accumulation of capabilities from low levels to advance is based on product diversity and the knowledge inputs, which was first through "using, doing and interacting" has changed to "science, technology... 

One of the newest methods of rapid prototyping is SLS . In this day, SLS is more common in compare others methods, because it uses little time and man does not nearly interfere in the producing stages of part which is made by SLS method. Also, sophisticated parts, which cannot be built by other methods, can be produced by SLS method. One of the disadvantages of SLS method is low dimensions accuracy of parts produced in this way. This problem has two major reasons: Shrinkage and Warpage. These two phenomena are created because of ununiformed temperature distribution. Others features which have effect on dimensions accuracy are residual stress, porosity and removing space of between powder... 

Expert retrieval when the number of experts are limited is an open problem. Undoubtedly, becoming an expert in a field is a time consuming and expensive task; thus finding the best candidates is a crucial task. In addition, passage of time and growth of knowledge could change the view of a person towards life and his work, which may lead to the change of his or her field of work. When considering the changes each person makes in his or her life, it becomes obvious that they are not far from the original status. Therefore, recommending all possible options around a person could really help the task of decision making. This research is addressing two similar issues of finding experts, in a... 

Self-driving car can move like an experienced driver without human intervention. For this purpuse, she must be able to fully understand and feel her surroundings like a human being. Accurate understanding of the surrounding environment in real time is one of the important factors that affect the performance of self-driving vehicles. Perception refers to the ability of an autonomous vehicle to collect sensor data, extract relevant knowledge, and develop contextual understanding of the environment, for example, identifying obstacles and the drivable area ahead the car. For this purpose, we use the Kitti dataset. This dataset is the largest dataset for machine vision algorithms for self driving... 

With the expansion of the use of renewable photovoltaic sources in electricity generation, the problem of uncertainty in predicting the production capacity of these sources has become one of the most important challenges of power networks due to dependence on climatic conditions, which is a random and uncertain phenomenon. Eliminating or reducing the stated problem requires economic policies that hold the producers of these resources accountable for deviating from the promised products in the day-ahead market. This thesis, the first place, proposes a fuzzy-neural prediction method with minimal input information considering the speed and accuracy of the prediction, which reduces the... 

In most of the engineering applications, the mechanical behavior of materials in high strain rate deformations differs from their behavior in quasi-static deformations. In some engineering problems like impact loading on structures, metal forming and explosive forming, the range of strain rate is about . Taylor impact test is one of the experiments used for characterizing the dynamic behavior of materials in high strain rate deformations. In the Taylor impact test a rigid cylindrical projectile is impacted normally onto a hard and massive surface (anvil), the projectile deforms by mushrooming at the impact end. With plastic wave propagation analysis, the plastic deformation of projectile is... 

Nowdays, Navigation sattelite systems are playing critial role in human life. In many equipments such as cell phone, transmitters , transportation systems ,etc. Accurate and reliable navigation is needed.
GPS was the first navigation sattelite system but today rival nations have delevoped or are developing parallel systems. These systems are Glonass operated by Russisa, Galileo by Europe and Beidou By china. GPS can not suffice human needs alone so the proposed solution is to exploit all above mentioned altenative systems. In this case, we can achieve higher accuracy, lower navigation time and more reliable navigation.
In this thesis the receiver is designed to receive all above... 

This thesis addresses cuff-less blood pressure (BP) estimation, for systolic blood pressure (SBP) and diastolic blood pressure (DBP) estimation with the aid of the processing of vital signals. Both with and without calibration per person approaches for BP estimation are considered. A data acquisition hardware is designed for high-resolution sampling of phonocardiogram (PCG), Photoplethysmogram (PPG) and electrocardiogram (ECG). Using these signals, pulse transit time (PTT) and pulse arrival time (PAT) indexes, which would be used for BP estimation with calibration, are extracted. For the BP estimator model using the calibration, A nonlinear model based on PTT or PAT, via modeling the vessels...