نشریه صنایع الکترونیک
سال هفتم شماره 4 (پیاپی 27، زمستان 1395)

Nowadays due to development of distribution systems and increase in electricity demand, the use of distributed generation (DG) sources and network reconfiguration in parallel are increased. This paper proposes a new multi-objective optimization to optimize network topology and allocation of DG in distribution network. In the proposed algorithm, ant colony optimization provides the network configuration and the artificial bee colony algorithm optimizes the location and size of DGs. An external repository is considered to save non-dominated (Pareto) solutions found during the search process. Moreover, a fuzzy-based decision maker is adopted to select the ‘best’ compromised solution among the non-dominated optimal solutions of multi-objective optimization problem. The objectives consist of minimize network power losses, better voltage regulation and improve the voltage stability within the frame-work of system operation. The proposed algorithm is implemented on the IEEE 33-bus distribution test system. Furthermore, the simulation results demonstrate the effectiveness of the proposed algorithm compared to those of other methods.

One of the most fundamental problems in industries is the initiation and growth of fatigue cracks before their destructive results. Consequently, various nondestructive evaluation techniques are proposed to eliminate mentioned concern. Although several accurate crack depth estimation methods have been proposed, they are not able to determine the error rate of theirs. Known upper bound error rate not only determines the maximum accuracy of a method, but also it would be feasible to arrange the least computational complexity based on desire error rate. Accordingly, as a result of the robustness of fuzzy methods over accessing to a closed-form of problems which have complex and empirical nature, a first and second fuzzy system is utilized to estimate the surface crack depth profile of an arbitrary crack in metallic structures based on ACFM signals, and employed to surmount mentioned drawbacks. Finally, to prove the advantages of the presented method in this paper comparing several common methods and analyzing its difficulties, numeric results of different simulations would be revealed in analytical and experimental forms.

In a Mobile Ad hoc Network, MANET, nodes move in the network area; therefore, the network topology is randomly and unpredictably changed. If the network topology is not controlled properly, the energy consumption is increased and also network topology probably becomes disconnected. To prevent from this situation, we have to use desirable dynamic topology control algorithms such as k-edge connectivity methods. In this paper, we try to improve the three following parameters according to the k-edge connectivity concepts: (1) network performance, (2) reduce energy consumption, and (3) maintain the network connectivity. To achieve these goals, as a new method, we enhance k-edge connectivity methods using an improved definition of node density. We will call the new method as: Node Density Based k-edge connected Topology Control (NDBkTC) algorithm. For the first time we use the node density definition dynamically. The new method, computes the node density based on a new equation which consists of the following factors: the relative velocity of nodes, distance between nodes, the number of nodes and the transmission range of nodes. The results show that our new method improves the network performance compared with the existing methods.

The ferrite rod or H field antenna operates using the high permeability of the ferrite material and in its basic form this may be thought of as "concentrating" the magnetic component of the radio waves. In this paper, parameter and simulation studies on low frequency ferrite loop antenna for LORAN receivers which require a center frequency of 100 kHz and bandwidth of greater than 20 KHz was reported. The simulation was performed in CST Microwave Studio. The antenna parameters such as sensitivity, radiation pattern and gain were simulated and discussed. The several factors affecting the gain of the ferrite loop antenna such as the number of wires, the magnetic constant of the ferrite rod and the position of coil also were studied. Through the parametric studies on ferrite loop antenna, an optimized performance is obtained. Prototypes are fabricated to confirm the simulation results. The experimental results indicate the good agreement with simulated results

One of the most important parts of a telecommunications system is the synchronization establishment between the transmitter and receiver. So in situations where the synchronization patterns are unknown to the receiver, it is necessary to find the frame structure and bit patterns, Otherwise is impossible transform the bit stream into clear text, or into reliable, cryptographic text, for further processing . Frame structures of different protocols at the physical layer have a fixed or variable lengths and each of these frames have one or more repetitive bit-patterns, depending on the application. . In this paper, a new algorithm for blind detection of bit-patterns in the different frame structures and the BSC channel noise is presented.
In this algorithm the first based on the concept of entropy, length of synchronization pattern is found, following by feature extraction on sliding windows, exact position of the synch pattern is found. It is shown that the proposed algorithm is highly efficient to detect one or more bit-patterns with the large or small length, in the long or short frames with fixed or variable frame structure, while the very low volume of available data and the noisy bit stream.

Mining frequent patterns over data streams is a challenging problem due to speed of input streams in real applications, processing and storage limitations. There are various models for mining frequent patterns over data streams. Time sensitive sliding window model is preferable due to modeling both concept change and varying speed of input data. Adding and removing transactions to/from sliding window leads to change in the set of frequent patterns. Approach to compute or approximate the frequency of new itemsets has a direct effect on the efficiency of the mining algorithm. In this study, for first time, a probabilistic estimation is used to approximate the support values for new frequent itemsets. Based on this approximation, a new algorithm is proposed which can mine the set of frequent pattern within a time sensitive sliding window. This algorithm benefits from a novel prefix tree based data structure to store the set of frequent patterns of the active window. Experimental evaluations performed on real life and synthetically generated datasets show the superiority of the proposed algorithm with respect to previously proposed approaches in terms of memory usage and runtime.

In this paper a new method of Impedance matching for microstrip line by tunneling of electromagnetic energy in epsilon near zero metamaterial are proposed. In this method the size of impedance matcher by use of this properties of ENZ that wave in whole ENZ is in phase, become smaller than other types of impedance matcher like quadrature wavelength transducer. In this method, the bandwidth of matching is related to bandwidth of ENZ. In this paper for implementation of ENZ we utilize of a rectangular waveguide that operate in TE10 mode. The bandwidth of proposed method is 10%-15% around the center frequency. By use of proposed method impedance matching for a 100Ω microstrip lines are simulated and designed.

Measured far-field radiation pattern of the antenna is one of the major issues in the antenna fabrication. The purpose of this article is finding the far-field pattern of an antenna by using planar near-field measurement simulation. Examination of the effective criteria is another point of consideration. Distance between probe and antenna under test, spacing grid and measurement plane dimensions are effective criteria that have been examined, that measurement to be modulated in a smaller space, with less time and simpler mathematical calculations. To achieve these goals, radiation pattern of X_band horn antenna has been simulated with full wave software. Near-field of this antenna is examined by using three different types of open ended wave-guide probes. Then near-field to far-field transformation is runed with software code and is compared with simulation results. It has been showed that rectangular probe has resulted better far-field pattern. The best distance between probe and antenna under test 3 wave length and best spacing grid 0.3 wave length are obtained. Finally the effect of probe pattern on test antenna pattern is examined and a method is suggested for probe pattern correction and antenna pattern in a large angular rang is implemented to far-field pattern of full wave software.

The main goal of this paper is to find a partial occlusion robust tracking algorithm. In addition, this algorithm should have superior performance against other tracking challenges and should have real time operation. In according to these reasons, we propose a two stage tracker based on coarse and fine sparse representation. At first, target object appearance modeled by a dictionary consisting of PCA basis vectors and trivial templates. We apply APG_L1 solving method for this modeling. We decrease number of trivial templates to decrease computation load such that we consider one trivial template for every a by a pixels. Then, best candidates in previous stage are evaluated by PCA_L1 method in order to determine the last candidate. We compare this tracker with 5 different popular algorithms and 7 new sparse trackers using 12 datasets. We conclude that proposed tracker with 14.2 frame per second, 10.2 average pixel center error, 0.7475 average overlapped rate, has a better performance in comparison with other trackers. And therefore simulations show that proposed tracker has a better performance in both accuracy and speed in comparison to other algorithms.

Using metamaterials in antenna design leads to interesting features includes size reduction, gain or bandwidth enhancement. In this article, the idea of using active circuits to compensate the admittance of electrically small antennas (ESA), in wide frequency range investigated practically. In this article, broadband ESAs based on active metamaterial structures designed, simulated fabricated and tested. To do this, a negative impedance convertor utilized as an active circuit to provide the effective impedance of metamaterial structure. Op-amp based structures as well as BJT transistor based on NICs investigated and discussed. Measurement shows tenfold reduction in resonance frequency while the fractional bandwidth increased up to 65% in BJT transistor based NICs while it enhanced up to 100% in op-amp based structure.