Sharif Digital Repository

In this study, irregularities of the mode shapes are utilized to determine the delamination situation in a composite laminated beam. Modal analysis is used to obtain the mode shapes of the beam; afterwards, the mode shapes are filtered to extract their irregularities. Presence of any delamination and its situation (number, size and location along the length and thickness of the beam) affects the extracted irregularities. Here, detection of delamination is based on these irregularities of the mode shapes. One of the most important advantages of this method is that unlike many other similar methods, in many cases, the mode shapes of damaged structure are sufficient and the exact mode shapes... 

Developing new micro and nano devices, help us instruction micro and nano devices in very small scales. Also nano technology improved in recent decades especially in century 21th. These devices contained many important members, such as micro and nano filters, micro channels, sensors, and electrical chipsets. Navier-Stockes equations with slip and no-slip conditions can not used in transition and free molecular regimes. Since most of the MEMS and NEMS devices working in slip and transition regimes, then we must using DSMC for simulation these devices. DSMC is a physically method and working on the physics bases. Also it was derived from Boltzmann equations by Bird. In this study, we want... 

Digital computers, comprising universal logic gates, are tremendously versatile. This versatility associated with the increasing integrability of digital electronics due to Moore’s law has left nearly no room for analog computers in the last few decades. However, in the case of some specific problems such as modeling complex and nonlinear systems or pro-cessing large amounts of data, computation time and power is still a serious restriction of digital computing. Optical phenomena are fast enough and offer novel approaches to overcome the mentioned restrictions about the system speed and power consumption. Therefore, optical structures make possible to perform ultra-fast spatial analog... 

E-plane waveguide filters are good choices due to highly manfacturing accuracy in Q-band microwave devices.To increase the attenuation slop or selectivity of such filters one need to synthesis transmission zeros with cross coupled resonators.With this method for constanst degree and return loss, attenuation slop increases in comparison to direct coupled resonators.
In this thesis we designed and fabricated a Q-band 4th degree filter,with center frequency at 42.1746 GHz and bandwidth of 350 MHz with two transmission zeros. Results of simulations and measurments are given in chapters 3 and 5.
Microwave filters using coupled resonators are important components in microwave systems.... 

Iran's electrical grid is connected to the Eastern Turkey grid via Khoy-Basqale 400KV transmission line. Harmonic mesurements indicate high level of the 5th harmonic voltage in Azarbayjan grid which is magnified in Van substation. According to Iran international obligations and economic losses caused by the high level of harmonics in Azerbaijan regional electricity grid, a comprehensive study is required. Early studies showed that this unprecedented increase in the 5th harmonic voltage is due to the small harmonic loads scattered throughout the network. The aim of this thesis is to perform a comprehensive harmonic analysis of Azerbaijan network due to scattered harmonic loads. In this... 

In this thesis, a method is presented for improving the observability of the heading angle in a UAV when using the Visual-Inertial navigation algorithm MSCKF by adding a magnetometer sensor. The proposed algorithm serves as a complementary extension to the primary algorithm, and efforts have been made to seamlessly integrate the magnetometer sensor into the primary algorithm to allow for easy modifications to the sensor's characteristics and to observe the resulting output in system simulations. Improving the observability of the heading angle will lead to an enhancement in the overall system state estimation. To achieve this, a new update stage is added to the existing algorithm.... 

In this document, the cooperative estimation of states between two interceptors and one target is expressed in order to evaluate the effect of information sharing in different situations on the estimation performance. Due to the importance of the proper estimation of the target acceleration in advanced navigation rules, the main focus of the document is on a more precise estimation of the absolute states of the target. For this purpose, a filter based on the extended Kalman filter was used as an estimator, and to evaluate the promotion of the estimation performance, the combination of measured data was used in two different ways. Matlab Simulink is the simulation software used. The dynamics... 

Since the beginning of discussion on neutron-gamma discrimination, different methods were suggested for this purpose. In early 2000s, Analogue methods were mainly used to discriminate the spectrum in mixed fields which mostly depends on electronic modules used in the lab setup; Nowadays, with improvements in digital pulse processing techniques, analyzing mixed neutron-gamma fields for pulse discrimination is also available.In this research, the recent MC developed toolkit called GEANT4 is used to simulate the 3-inch BC501A scintillation detector and 500 mCi Am-Be source (that emits neutron and gamma at the same time). For the next step, an experiment with same source and detector was done... 

Due to the technological improvement, decreasing transistor’s size and increasing demand for more processing abilities, designing and implementing multi core processors becomes a hot topic. One of the direct effects of decreasing the size is increasing the rate of power consumption in a unit area. Thus, the generated heat by the processor will be increased. Increasing the temperature could has undesired effects on the other features of the processor such as reliability, efciency, and failure rate. The problems that caused due to the high temperature in the multicore processors is not limited to the maximum temperature, but temperature fluctuations and variation between different parts of the... 

In this research, using orthonormal filters, an adaptive-robust controller is designed for a class of SISO dynamic systems for which the input and output datas are available. First, Laguerre filters are combined with orthonormal Chebyshev functions to increase the capability of Laguerre filters in identification of systems with unknown dynamics. Then, the resulted Lagueree-Chebyshev structure is used for closed loop identification of the system and controller is designed. Moreover, RBF neural networks are used to approximate some nonlinear terms appearing in the controller design process.
Finally, in order to minimize the control effort, a new approach is proposed that leads to a set... 

One of the serious challenges in Ultra-Wideband (UWB) systems, especially Impulse radio (IR) systems, is the IEEE 802.11a in the middle of the UWB band (In band Interferer) which affects the system performance severely. Matched filter concept shapes the output noise based on its spectrum. For solving the mutual interference between UWB and narrow-band (NB) systems, the unique properties of modified Hermite pulses is utilized to develop a pulse for UWB communications. Matched filter is implemented by designing this pulse featuring notches that can be tuned to a certain frequency. Therefore, NB interferer can be nulled out passing through the matched filter. 0.18 µm CMOS technology has been... 

Tehran Refinery, as an industrial center that has significant water consumption in Tehran, intends to use the flow of water from the treatment plant south of Tehran after final preparation, with the aim of managing water resources and meeting its needs. And it uses a biological activated carbon (BACF) filter to reduce the DOC concentration. In these filters, the removal of organic matter is performed by the adsorption process as well as the biodegradation process by microorganisms grown on activated carbon. The presence of biofilm leads to continuous bio-regeneration of activated carbon during the water treatment process. Therefore, in this study, by examining the performance of these... 

Fractional Order Transfer Functions (FOTF) in comparison to Integer Order Transfer Functions, have higher degree of freedom and as a result they can behave more dynamically. Many methods for approximation of these transfer functions have been developed in recent years allowing to implement and simulate their time-domain and frequency-domain characteristics.
Fractional order orthonormal Laguerre filters are a generalization of conventional orthonormal Laguerre filters in fractional order transfer functions domain. Orthonormal Laguerre filters have applications in signal processing and system identification. In this thesis, we investigate the application of fractional order laguerre... 

In modern wireless mobile telephony networks, DS-CDMA based physical layers has gained much attention due to their ease of implementation at relatively low overall cost, ability to provide high speed data services, increased user capacity, and many other outstanding features. One of the challenges facing these systems is the synchronization of the users’ signature codes (received via communication channel) to the receiver’s locally generated replica, as the only distinguishing feature between users in such systems is the pseudo-orthogonal properties of these signature codes. To fully utilize this orthogonality, all sequences need to have a common time reference. But when relative sequence... 

EEG Signal Processing has really important role in study of nerves system and nervous diseases. In most applications, signals occur in the frequency band ranging below 100 Hz are considered. In this study, the higher frequency components of the signal, especially in patients with epilepsy, reported which they are called high frequency oscillations (HFOs). Some sources considered that HFOs are up to 1000 Hz and some other considered up to 2500 Hz. In study of HFOs, the high frequencies between 100 and 200 Hz that are called ripple and seen in normal mode are separated from the faster frequencies from 200 to 500 Hz and these components can accurately help to detect epileptic foci generator (to... 

Frequently using Personal Identification Information has escalated the security concerns of bank accounts, emails, daily transactions, and other activities. Therefore, user access to such apps must be controlled. Traditional personal verification methods offer limited security because they might need to be remembered or stolen. Therefore, Biometric authentication, which identifies persons by their unique biological information, is gaining popularity. However, palm vein identification is highly secure because the vein patterns are not duplicated in other people, even in monozygotic twins. Moreover, it has a liveness detection and is convenient since the vein pattern cannot be faked,... 

The hulls of various ships are exposed to the problem of biofoulings on the hull after a period of time due to use in the salt water environment of the sea and the existence of suitable conditions for the growth of marine plants, so that the ship after about one month of stopping in the port, in order to start the activity again, it is necessary to clean the hull from these biofoulings. The ship will be transported to the dry dock for cleaning only when it is heavily involved in biofoulings on the hull, and in the meantime, it must be periodically cleaned in water by other systems, including the diver and robotic systems.Using a robotic system to perform this operation has various... 

The problem of concurrent attitude and orbit estimation (CAOE) of satellite using its surface thermal data is studied and investigated in the present dissertation. Considering various uncertainties associated with the satellite system and its surrounding with regards to thermal issues, the dissertation subject and its application to CAOE is challenging and of importance. To this aim, the space thermal model for low Earth orbiting (LEO) satellite is initially reviewed and presented. Since the Sun and the Earth are considered as significant sources of radiation for near Earth space systems, the view factor is a key parameter for orbit observability and estimation via surface thermal data.... 

As part of the definition of concept drift as an online learning task, concepts change or drift as time goes by. Consequently, these changes have to be monitored and their implication for learning should be recognized. An example of concept drift detection is needed for spam filtering problem. An effective spam filter must be able to handle various changes, including changes in the user’s criteria for filtering spam, changes in message topics, and changes caused by the people sending spam messages. In this thesis, spam detection system has been considered in which emails are given sequentially and learns them one by one. As we mentioned, the purpose of this thesis is detecting spam emails.... 

Microrobots are the robots which manufactured or operated in micro dimentions. High accuracy, compatibility with harsh situations and caring or assembling in micro dimensions are the most important advantages of these robots. Manufacturing new microrobots with higher speed or increasing the velocity of existed microrobots is the discussion of these days.An A-shape microrobot designed and manufacturared before. The goal of this thesis is to model, identify the friction and observe the velocity of the A-shape microrobot. In low speeds both legs of microrobots are on the ground; it walks with the stick-slip motion principle. Increasing the velocity of the microrobot causes separation of one or...