In this paper a new soft switching boost-flyback converter is introduced to eliminate conventional boost-flyback converter problems in the high voltage applications. The main application of this converter is conction of PV system to the power system. In the proposed converter not only the operating duty cycles proper in high voltage gains but also the switch voltage stress is lower than output voltage. Also, in the proposed converter any auxiliary switch or magnetic core has not been used so the number of converter components has not increased much in comparison with the conventional boost-flyback converter. The operation principles of the proposed converter and its theoretical operation waveforms is presented. In order to justify the theoretical analysis, a prototype of the proposed converter is designed, simulated and experimentally implemented. The simulation and practical results are presented for a 100w boost-flyback converter with input voltage of 40V and output voltage of 400V.
sun is of the clean and cheapest sources of energy. Charging slight energy to electricity is carried out by PV modules. Since most electric consumers need Ac input voltage, the PV modules output voltage should be changed into Ac form. But, the voltage level of PV modules is much lower than the voltage needed in input stage of inverters. Because of large voltage level. Difference it is not possible to use the basic boost and buck-boost converters. The basic boost and buck-boost converters definitely can not be used in this applications, for, they will face extreme drop in efficiency in duty cycles closer to unity. In this paper The proposed converter is presented in order to decrease the voltage stress of coupled inductors based high step-up converters. The voltage stress in the proposed converter is lower than the high step-up boost converter with coupled inductors in identical condition. Also, soft switching condition for switches and diodes is realized by active clamp circuit, and with this technique and proper selection of duty cycle, large gain and high efficiency could be achieved ultimately. . In this paper theoretical analysis is used for analyzing the performance of the proposed converters, and in order to verify the theoretical analysis, simulated results from pspice software is provides.
In order to quality service improvement, digital video broadcasting terrestrial should increase both channel capacity and also data rate. The system should be stable against fading. To achieve this aim, using multiple input multiple output which is equipped by dual polar antennas with low correlation is practical. However, using polar antennas lead to interference creation caused by cross polarization. This issue bring the decrease of both data rate and transmit capacity. To decrease the influence of depolarization, applying successive interference cancellation (SIC) is very effective. In this paper, a new detection algorithm based on SIC detection is proposed. The main characteristics of this algorithm is changing in the SIC detection nulling. This article also shows that, in environmental with high fading, in contrast to other detection method like ZF-SIC and MMSE-SIC, bit error ratio performance versus SNR is improved in new proposed detection method.
The distillation process is important process in the chemical industry and has wide application in industry. Distillation tower is used by chemical engineers as a popular tool to separate materials and is the most common method for separating materials. Keeping constant the product composition in the distillation column is very important from control perspective. Control of these complicated processes need intelligent methods to adopt the appropriate decision for control based on the behavior of the system. Between intelligent methods, fuzzy technique has superior response in complex systems control and so is used in this study. In this article at first, a type-1fuzzy controller is designed for linear model of distillation tower. In design of this Fuzzy controller, genetic algorithm (GA) is used for optimization of fuzzy rules base. It has been shown that the fuzzy controller is better than conventional PI one. Then the type-1 fuzzy controller has been replaced with type-2 fuzzy controller and has been shown that the performance of type-2 is better than type-1 in various points of view. In this study, the MATLAB/SIMULINK software has been used for modeling and implementing the proposed methods.
Wireless Sensor Networks, have found plenty of applications, nowadays. Due to the presence of tiny and restricted batteries in these little sensors, deployment of a power-efficient routing protocol is a must. Between all the already-proposed routing protocols, the hierarchical ones are more efficient in energy conservation than flat routing protocols. In order to decrease energy consumption and increase the network lifetime, we proposed a new hierarchical routing protocol, by dividing the network area to sectors and two levels and choosing Cluster Heads from the lower level, which is more near to the Base Station. In order to minimize the reverse flow of the data from BS, we use a tree structure in each sector. In addition, the frontier between two levels can be moved during network lifetime and having dead nodes. The results of simulations show that our proposed TSBC protocol outperforms LEACH, Multi-Hop LEACH and many other conventional routing protocols in energy conservation and in network lifetime. One of the most important properties of our scheme that can distinguish it from any other scheme is reverse flow from BS cancellation or at least deduction. The special formula, which is used in our protocol for CH selection, in order to prevent battery depletion in a special spot, can also be adapted to any other hierarchical clustering protocols to achieve higher energy-efficiency. It is still noteworthy to mention that thanks to devising special measures we highly prevent fragmentation occurrence in routing process in the network.
This paper addresses the cross-layer design for multicast routing in Multi-Radio Multi-Channel Wireless Mesh Networks (MRMC-WMNs) with directional antennas. WMNs have a limited capacity because of existence of interference between the wireless links. This issue becomes more crucial in the multicast communications. Directional antennas can focus the transmission power to the limited sector. Thus, equipping the wireless nodes with these antennas leads to degrade interference. This paper proposes two cross-layer algorithms named “Directional Multicast Tree Construction (DMTC)” and the “Directional Interference-aware Multicast Tree Construction (DIMTC)” to solve the aforementioned problems. In the first algorithm, we jointly consider the channel diversity; the wireless broadcast advantage and the directional antenna technology to reduce number of transmissions in the routing trees. In the second one, in addition to above factors we use interference aware path selection factor to eliminate the interference among the multicast sessions. This scheme is aiming at improving the utilization of radio resources reducing both number of transmissions and interference, at the same time. Simulation results demonstrate that our schemes are more efficient than other existing schemes as well.
One of the most prominent challenges in meeting the demand is the scarcity of radio resources. Cognitive radio is one of the techniques has been proposed for efficiently utilizing the radio resources. In Cognitive Radio CR) networks, the CR users have opportunities to access the licensed spectrum bands assigned to the primary users (PUs). Since the PUs have priorities to use the bands, the CR users are not allowed to generate unacceptable interference to them. In this paper, we investigate power allocation schemes for CR networks with two users where one users uses direct transmission and the other uses AF relay-aided transmissions. We first formulate an overall rate optimization problem with interference constraints to the PU and peak power constraints at each node and obtain solutions by theoretical analysis. We also simulate the solution base on different location of the relay and different location of the PU network.we compare the results with equal power allocation.
In this study, a new algorithm for dermoscopy image classification into two types of malignant and benign is presented. At first, one preprocessing step to remove noise and also enhance image quality is performed. After that using Otsu thresholding, the lesion is separated from the healthy area. Then color and shape features are extracted from the segmented image. The colored features based on statistical moments of quantized grayscale and quantized color histogram are defined. These features demonastrare distribution of color components. Moreover, the shape features are extracted information of the segmented regions with two scenarios. In the first scenario, the features are represented the expantion of region and in the second scenario, the features are represented the edge variations of the extracted regions. Finally, the classification procedure is performed using K-Neasert Neighbor (KNN), Decision Tree, Support Vector Machine (SVM) and Adaboost. The proposed algorithm is evaluated on a standard database consisting of 200 images. The results show that classification using Adaboost classifier obtains the precision rate, accuracy rate and sensitivity rate of 96%, 96.7% and 95%, respectively.
In this paper a new idea of direct three-phase to single-phase Z-source matrix converter (impedance-source matrix converter) applicable in stand-alone wind turbine is introduced. In the direct Z-source matrix converter amplitude of output voltage and frequency regulation are of importance to control system. In wind turbines, input voltage and frequency are usually changing due to wind speed variation that these alterations could be easily regulated by means of a direct Z-source matrix converter. A scheme is also offered to control the proposed direct three-phase to single-phase Z-source matrix converter. the control strategy would be able to adjust the output voltage and frequency at desired value as well as producing low THD (total harmonic distortion) at the output voltage. The proposed structure and the control methodology are simulated using matlab simulink software and results are investigated and discussed to confirm the performance of the direct Z-source matrix converter in wind turbine.
In this paper, the influence of design parameters on the sensitive microphone diaphragm for use in implantable medical applications is presented. The different parameters such as diaphragm shape, size, thickness and different applied pressures on the diaphragm has been considered. The effect of changes in these parameters on the displacement and stress in a variety of shapes of diaphragm is discussed. In order to design the optimal shape of the proposed diaphragm for the considered parameters, it has been simulated and analyzed in software COMSOL. According to the parameters, the diaphragm shapes of square, rectangular and oval with respect to the intended user, average central displacement in human hearing frequency range 20Hz-20KHz are nm 5. 5, nm2. 6, and nm 130 respectively . According to the results of the simulations, the oval-shaped diaphragm that has been studies in this paper, the possibility of implanted medical applications, performance is optimal than other shapes. In addition, the piezoelectric material is PZT which used in the design of the diaphragm.
Protection of equipment, safety of persons and continuity of power supply are main objectives of the grounding system. For its accurate design, it is essential to determine the potential distribution on the earth surface and the equivalent resistance of the system. Knowledge of such parameters allows checking the security offered by the grounding system when there is a failure in the power systems. A new method to design an earthing system using Finite Element Method (FEM) is presented in this article. In this approach, the influence of moisture and temperature on the behavior of soil resistivity are considered in earthing system design. The earthing system is considered to be a rod electrode and a plate type electrode buried vertically in the ground. The resistance of the system which is a very important factor in the design process is calculated using FEM. FEM is used to estimate the solution of the partial differential equation that governs the system behavior. COMSOL Multiphysics 4.4 which is one of the packages that work with the FEM is used as a tool in this design. Finally the values of the resistance obtained by COMSOL Multiphysics are compared with the proven analytical formula values for the ground resistance in order to prove the work done with COMSOL Multiphysics.
this paper has scrutinized an effective approach regarding to how to elicit double quasi-sinusoidal waveform with orthogonal angles that can be applicable for two-phase induction motors. Hither, to be more precisely declared that a switching strategy is proposed so that the provided voltages by Matrix Converter (MC) i.e., A and B phases have 90⁰ difference with each other. This switching strategy assists two-phase induction motors aimed at operating in appropriate state. As the created frequency in an important item for this motor, matrix converter can also undertake this function. It is worth mentioning that, the switching is somehow performed until bio-directional switches couldn’t be simultaneously triggered and withal taken place in the accurate switching order. Its related circuit in order to producing appropriate current and voltage has been tested considering MATLAB Simulink and experiment. The simulation result is extracted with respect to inductive and resistive load. Meantime, PWM method is carried out to extract experimental results that clearly show its effectual performance.
In this paper, lift and drag forces of permanent-magnet electrodynamic suspension (PMEDS) System have been studied by considering the skin effect. Electrodynamic suspension is based on repulsive force between two magnetic fields with the same polarity. In this research the electrodynamic suspension system consists of a moving permanent magnet block levitated over a flat conducting plate with 2 mm thickness. At first, the analytical model of the PMEDS is proposed. For this propose, permanent magnet poles are modeled by the current sheets. Then the eddy current is calculated on aluminum sheet by considering the skin effect. Finally, the lift and drag forces are calculated in difference speed. The 2D finite element method is utilized to investigate the effect of speed variations on the performance of PMEDS at two different airgap. Two-dimensional finite element model, the accuracy of proposed analytical model is validated. The results of the finite element method are compared with results obtained by analytical model. It shows the accuracy of the analytical model in the estimation of the lift and drag forces of an electrodynamic suspension system.
When a turbine–generator set connect to a long transmission line, may results side effects such as Sub-Synchronous Resonances (SSR). The capabilities of the Distributed Static Series Compensator (DSSC) as a member of the family of D-FACTS can be used to reduce these SSR. To achieve this desired goal, the fuzzy controller, Particle Swarm Optimization (PSO) and artificial neural network is used to control of the DSSC. Particle swarm optimization is designed Based on the Conventional Damping Controller (CDC) and fuzzy logic is designed based on damping controller (FLBDC) and damping control based on artificial neural network trained using the fast pace of changes has been designed. Stability of the system is analysed by simulations in the time domain with performance index (PI). All simulations are done using Matlab / Simulink software. Case studies show that proposed algorithms can reduce SSR in the system.All simulations are done using Matlab / Simulink software. Case studies show that proposed algorithms can reduce SSR in the system.
Speech is the basic mean of communication among human beings.With the increase of transaction between human and machine, necessity of automatic dialogue and removing human factor has been considered. The aim of this study was to determine a set of affective features the speech signal is based on emotions. In this study system was designs that include three mains sections, features extraction, features selection and classification. After extraction of useful features such as, mel frequency cepstral coefficient (MFCC), linear prediction cepstral coefficients (LPC), perceptive linear prediction coefficients (PLP), ferment frequency, zero crossing rate, cepstral coefficients and pitch frequency, Mean, Jitter, Shimmer, Energy, Minimum, Maximum, Amplitude, Standard Deviation, at a later stage with filter methods such as Pearson Correlation Coefficient, t-test, relief and information gain, we came up with a method to rank and select effective features in emotion recognition. Then Result, are given to the classification system as a subset of input. In this classification stage, multi support vector machine are used to classify seven type of emotion. According to the results, that method of relief, together with multi support vector machine, has the most classification accuracy with emotion recognition rate of 93.94%.
Nowadays one of the specialized and important issues in construction of marine floats is to design the communication telecom system between them. Always this issue has been posed how to establish an appropriate communication for floats in different distances and different weather conditions in the sea. Due to the restrictions, such as equipment size, weight bearing on the floats has always existed.One of the main parts of telecom communication system is antenna.The main problem, use antennas and Towers various in floats, As required, waves with different wavelength sand different routes to be published. If the antenna can be designed with small dimensions and possible,wide frequency range and also covered omni-directions, the problem has been mentioned above somewhat is resolved. The purpose of this paper is to design and simulate of a sample of integration broadband antenna and omni-directional, that resolve About restrictions above and Integration of two antennas in frequency range of VHF/UHF=150-450MHZ and HF=3-30MHZ with characteristics of 50ohm input impedance, linear vertical polarization, VSWR<2.5, antenna gain ranges between (-12)dBi to (4.8)dBi, the maximum antenna diameter of 18cm, and the maximum height of opened antenna of 538.2cm.
In this paper, a single switch transformerless high step up dc-dc converter with low voltage stress on the switch is proposed. In the proposed converter only one switch is used which makes the control scheme simple as well as reducing the switching power loss. The voltage gain of the proposed converter is higher than the conventional boost converter and buck boost converter and Proposed converter works in wide rang than conventional converters. The proposed converter has low voltage stress on the switch which makes reducing the switching power loss. The proposed converter can be operated in the continuous conduction mode (CCM) and the discontinuous conduction mode (DCM). In this paper, different operation modes of the proposed converter, calculation of the voltage gain, the currents that flow through the components, efficiency and capacitors voltage ripple are presented. To verify the operation of the proposed converter, simulation results via PSCAD software and experimental results are provided.
In this paper, a new prognostic index to detect the severity of asthma by processing capnogram signals is presented. Previous studies have shown significant correlation between the capnogram and asthmatic patient. However, most of them used conventional time-domain methods and based on assumption that the capnogram is a stationary signal. In this study, by using linear predictive coding (LPC) coefficients and autoregressive (AR) modelling (Burg method), the capnogram signals are processed. Then, a number of six features including α1, and α4 from LPC and power spectral density (PSD) parameters through AR modelling are extracted. After that, by means of receiver operating characteristic (ROC) curve, the effectiveness of the extracted features to differentiate between asthmatic and nonasthmatic conditions is justified. Finally, selected features are used in a Gaussian radial basis function (GRBF) network. The output of this network is an integer prognostic index ranging from 1 to 10 (depends on the severity of asthma) with an average good detection rate of 90.15% and an error rate of 9.85%. In the other word, based on the results, sensitivity and specificity of this algorithm are 93.54% and 98.29%, respectively. This developed algorithm is purposed to provide a fast and lowcost diagnostic system to help healthcare professional involved in respiratory care as it would be possible to monitor severity of asthma automatically and instantaneously.
Quality of Service (QoS) provisioning is very important in next computer/communication networks because of increasing multimedia services. Hence, very investigations are performed in this area. Scheduling algorithms effect QoS provisioning. Lately, a scheduling algorithm called Regulated Burst Service Scheduling (RBSS) suggested by author in [1] to provide a better service to bursty and delay sensitive services such as video. One of the most significant feature in RBSS is considering burstiness of arrival traffic in scheduling algorithm. In this paper, an upper bound of queue length or buffer size and service curve are calculated by Network Calculus analysis for RBSS. Because in RBSS queue length is a parameter that is considered in scheduling arbitrator, analysis results a differential inequality to obtain service curve. To simplify, arrival traffic is assumed to be linear that is defined in the paper clearly. This paper help to analysis delay in RBSS for different traffic with different specifications. Therefore, QoS provisioning will be evaluated.
هصلاخ نف ،هزورما : ويدار يروآ هرهب فده اب يتخانش ر عبانم زا ايوپ يرو رد ييويدا هب ،سرتسد هكبش يارب يديدج يوگلا ناونع يتارباخم ياه يم بوسحم هتسب لاسرا هب رجنم ،يتخانشويدار هكبش كي ناربراك نيب رد يسناكرف فيط هب يبايتسد رد ينوگمهان يگژيو .دوش قيرط زا هداد ياه لاناك ،هلأسم نيا .دش دهاوخ هكبش يهدرذگ شهاك ،هجيتن رد و هناگدنچ ياه كيفارت روضح رد شلاچ اب يشخپدنچ ياه هجاوم يرتشيب ياه يم شهاك ،هلاقم نيا يلصا فده .ددرگ هرود كيفارت ينامز هكبش رد يشخپدنچ ياه يب يروت ياه دنچ يتخانشويدار ميس .تسا هلاناك اذل ، رب يعس هك تسا نآ هرهب اب يريگ زا مأوت تسايس نامز دمآراك ياه مه يگژيو ،يشخپدنچ يدنب ه هكبش رد يشخپ يب ياه يراذگدك ،ميس و شور ياه فلتخم ياهورگ ياضعا و هورگ كي ياضعا يتكراشم ،هكبش ميزادرپب هكبش ييارجا تيلباق دوبهب هب . اتسار نيا رد صاصتخا اب ، نداد ياهويدار هناگدنچ هب لاسرا ناكما ،هكبش ربراك ره تفايرد و لاناك يور نامزمه مهارف ار فلتخم ياه يم فيط چيه هك يطيارش يارب ،اهتنا رد .مييامن طابترا يرارقرب تهج يسناكرف ميقتسم اب ربراك كي يزكرم بايريسم شور كمك هب ،دشاب هتشادن دوجو همه يگژيو رانك رد يتكراشم ياه يشخپ هكبش رد يب ياه يم هئارا يديدج راكهار ميس ولاع ات مينك يرادياپ رايعم ظفح رب ه رذگ دوبهب هب رجنم زين هكبش يهد .دوش
