فصلنامه روشهای هوشمند در صنعت برق
پیاپی 16 (زمستان 1392)

In this paper، a novel microstrip-line ultra-wideband (UWB) bandpass filter (BPF) based on multiple-mode resonator (MMR) is designed، analyzed and simulated. The structure of the proposed MMR constructed by a modified triple-mode stepped-impedance resonator (MSIR) loaded with a folded step-impedance stub (FSIS). This stub-loaded resonator could generate two more resonate modes and two transmission zeros (TZs) simultaneously. Proposed MMR’s dimensions properly tuned so that first five resonate modes of the proposed MMR roughly allocated in the desirable bandpass، i. e. 3. 1-10. 6GHz، as well as two TZs at the edge of the passband، leading to sharp roll-off. Finally، with using aperture-backed interdigital-coupled lines for feeding، an UWB BPF with compact size، high selectivity، good performance in-band، and wide stopbands is obtained. Simulation results are in excellent agreement with UWB BPF ideal case.

High speed boats are small kind of boats which are piloted with boatman. These boats are usually used in strategic commissions like military which fast speeds and good manoeuvrability are of essential importance. Rough sea path، marine turbulences and multi input multi output nonlinear dynamical model of this boats،make it very difficult to pilot and manoeuvre them. in this paper،. two controller are designed and proposed for pursuing desired path and manoeuvring fast speeds. Fuzzy controller is compared with the result of PID controller. Simulation results also indicate that these proposed controllers have suitable responses and can pilot the boat in the best manner.

Application of fractional order proportional integral (FOPI) controller to improve transient performance of wind turbine (WT) with Doubly fed induction generator (DFIG) is presented and studied in this paper. By small signal analysis، it is found that the dynamic behavior of the DFIG based WT، during the variation of operating conditions، is strongly affected by the stator dynamics. Since the DFIG electrical dynamics are nonlinear، the linear control (PI) scheme cannot work properly under change in wind speed and stator modes are not damped appropriately. The proposed fractional order controller generalizes the conventional integer order PI controller whose integral order are fractional number rather than integer. This expansion can provide more flexibility in achieving control objectives. By time domain simulations، a comparative analysis is made with respect to the standard PI controller to demonstrate effectiveness of the fractional order PI () controller during wind speed perturbation.

In this paper، a new Laguerre controller is proposed to control the electro hydraulic servo system. The proposed controller uses feedback error learning method and leads to significantly improve performance in terms of settling time and amplitude of control signal rather than other controllers. All derived results are validated by simulation of nonlinear mathematical model of the system. The simulation results show the advantages of the proposed method for improved control in terms of both settling time and amplitude of control signal.

Dermoscopy is one of the major imaging techniques used in diagnoses of Melanoma and other skin diseases. Because of difficulties and subjectivity of human interpretation، automatic and computerized analysis of dermoscopic images has opened an important research area. Automatic lesion detection is one of the main steps in analysis of these images. Finding an optimal threshold for segmenting the lesion is a severe task in image processing. Different methods for thresholding already exist. In this research a novel thresholding approach according to well-known thresholding methods and reinforcement algorithm for segmenting dermoscopic images is presented. The reinforced agent learns optimal weights for different thresholding methods and finally segments the dermoscopic image with optimal threshold. A reward function is designed for achieving the similarity ratio between the binary output image and original gray level image and calculating reward/punish signal which should be exerted to reinforced agent. We use three thresholding methods، Otsu، Kittler and Kapur، for combining in the reinforced agent and the detected lesions are compared with the ground-truth which is determined dermatologists and the border error is calculated. The results are also compared with other well-known automatic methods which indicate that the proposed method yields to more accuracy and less border error in detection of lesion in dermocopy images.

Multimedia traffics are the basic traffics in data communication networks. Especially Video conferences are the most desirable traffics in huge networks (wired، wireless، …). Traffic modeling can help us to evaluate the real networks. So، in order to have good services in data communication networks which provide multimedia services، QoS will be very important. In this research we tried to have an exact traffic model design and simulation to overcome QoS challenges. Also، we predict bandwidth by Kalman filter in Ethernet networks.

Polymer fuel cell is one of the most attractive of fuel cell from point of the design and operation and also in comparison with other types of fuel cell، for a weight and size، polymer fuel cell produces more power. But however، one of the problems to use of this system is its low efficiency. To overcome the low efficiency of the fuel cell polymer in this paper is tried to used from maximum power point tracking. According to the characteristic of the flow –power the fuel cell، which is a non-linear curve and has a maximum point and use of the fuzzy controller and the proper selection of input and output membership functions trying to the System always works at maximum power. For this purpose، a chopper is used between the fuel cell and the load and to adjust the duty cycle of the applied signal to it is applied the fuzzy-TSK type controller that Its inputs are stream slope and slope changes. The results show that this controller has a good performance and that is faster compared with the perturbation and observation method.

In this paper، the problem of the position and attitude tracking of an autonomous underwater vehicle (AUV) in the horizontal plane، under the presence of ocean current disturbances is discussed. The effect of the gradual variation of the parameters is taken into account. The effectiveness of the adaptive controller is compared with a feedback linearization method and fuzzy gain control approach. The proposed strategy has been tested through simulations. Also، the performance of the propos-ed method is compared with other strategies given in some other studies. The boundedness and asymptotic converge-nce properties of the control algorithm and its semi-global stability are analytically proven using Lyapunov stability theory and Barbalat’s lemma.