نشریه صنایع الکترونیک
سال هفتم شماره 1 (پیاپی 24، بهار 1395)

In this paper a hexagonal Photonic Crystal Fiber (PCF) structure with Unequal hole size in silica core is proposed. By compromising between dispersion, Effective Area, confinement loss and the number of propagation modes, the higher orders of dispersion can be reduced significantly. Simulation results demonstrate that, zero flattened dispersion with very low slope over a wide wavelength range of 1.2μm to 1.6μm in abnormal dispersion region with single mode propagation can be achieved. By passing a 28fs laser pulse with a maximum power of 5kw in a 15cm long of such a PCF, supercontinuum output spectrum is simulated over the wavelength range of 1.4μm to 1.62μm.

This paper describes a new application of a low cost MEMS gyro for small satellite`s attitude determination, as well as a calibration procedure. Because of space application and there is not linear acceleration in this environment, for the first time g-dependent bias effect on sensor`s data is considered and a new method to calculate the level of this effect and elimination of that is proposed. For this aim one-axis exact rate table is used and a temperature compensation method is proposed to remove the effect of temperature variation on bias and scale factor. This measurement unit contains three orthogonally mounted MEMS gyros. Using one-axis rate table is applied to solve the problem of accessing to the three-axis one. The accuracy of sensor is considerably improved by correction of misalignment error. Experimental results verify the proposed calibration method of three axis MEMS gyro.

In this paper, a new method is presented for solving the energy optimization problems. The goal is to find the optimal Energy Resources are Distributed (DER). so that minimizes the cost of the total operations. The methods we use in this paper is genetic algorithms, particle swarm algorithm and modified cuckoo optimization algorithm that genetic and particle swarm algorithms used to compare. Finally we use the proposed method which is modified cuckoo optimization Algorithm in the test Micro Grid (MG). Results show that the proposed algorithm, in addition to providing electrical necessity of Micro Grid, it can be excellent of economically, which is the goal of this paper.

This paper uses a new meta-heuristic called Grey Wolf Optimizer (GWO) for classifying sonar data set. The GWO algorithm imitates the leadership hierarchy and hunting mechanism of grey wolves in nature. It also employs four types of grey wolves including alpha, beta, delta and omega for simulating the leadership hierarchy. In addition, the three main steps of hunting including searching for prey, encircling prey and attacking prey, are simulated. The algorithm is then benchmarked on 23 well-known test functions and the results are compared with Particle Swarm Optimization (PSO). The results show that the GWO algorithm provides better results in finding total minimum of functions, convergence speed and local minima avoidance compared to PSO. In addition, in this paper a real application of proposed method in the field of sonar data set classification is presented. The results show that the designed classifier inspired by grey wolves can classify the sonar data with accuracy of 96.67%; whereas the PSO presents the accuracy of 92.23%.

LORAN land-based system is a radio navigation system using land-based radio transmitters and receivers to allow mariners, aviators, and those interested in terrestrial navigation to determine their position. The accuracy of Loran land-based system is affected by various factors that one of most important factors is the geometry of transmitters relative to receiver position. This effect is calculated with a non-dimensional parameter called Dilution Of Precision (DOP). There are various methods for calculating GDOP that are: particular bisector method, general azimuthal method and Torrieri method. The aim of this research is calculating of DOP base on these methods for triple Labrador chain and comparing the results together. Then a new algorithm is represented for calculating GDOP based on distance between receiver and transmitter similar to using existing GPS algorithm that based on results of Labrador chain, this method in comparison with other methods presented optimistic results. Also, this paper introduces an algorithm for finding the best geometry of transmitters according to position of the receiver. This algorithm is used for Labrador chain and results indicates that this geometry in comparison with existing geometry of this chain, prepare the minimum values of GDOP for the receivers of this region.

In this paper, a wideband Voltage-Controlled Oscillator (VCO) is presented that operates in 2.38GHz to 3.9GHz, representing 48.6% tuning range. This circuit has been aimed to the wireless and WiMAX networks. The proposed circuit has low KVCO (frequency variation per 1V) and hence, reduced spur, when used in a Phase Locked Loop (PLL). This work also proposes a new method for optimization of capacitors values and transistors size in the capacitor bank. Phase noise of the proposed circuit is -120.8 dBc/Hz at 3.9GHz center frequency, at 1MHz offset. The supply voltage is 1V and the power consumption is 4.1mW. The proposed circuit has been laid out using TSMC 0.18 um RF CMOS foundry design kit in CADENCE. The post-layout simulation results prove excellent performance of the proposed circuit.

In this paper, the purpose is spacecraft trajectory design and correction in de-orbit maneuver. According to the ýsystematic requirements, this maneuver is required for a real project and its parameters and values have been ýset by its system engineering team. In order to achieve the desired maneuver, propulsion system must produce ýthe velocity change vector. In practice, due to the unsatisfactory performance and uncertainties in the ýpropulsion system, ideal velocity change vector may not be realized. Consequently, spacecraft deviates from ýthe desired de-orbit trajectory and it is possible the spacecraft mission fails. So as to avoid this problem and ýcompensate the created deviation, a controller based on Cowell’s formulation and using feedback linearization ýmethod is designed and its performance, after generating and loading desired de-orbit trajectory in the control ýlaw (using the orbital elements), will be examined during a de-orbit maneuver. In this article, for a considered ýimpulsive de-orbit maneuver, velocity change vector and its execution time which are necessary for transfer ýfrom initial orbit to the de-orbit trajectory, are calculated. The simulation results indicate that, due to technical ýconstraints and the capacity of the propulsion system, the maximum error of de-boost impulse value and ýorientation which the controller can compensate are 15% and 20% respectively.

Image matching is one of the important issues in the machine vision science and is the basis of many systems in the field of artificial intelligence. It is mainly used in object recognition in robotic applications, data acquisition and analyzing the received data from satellite, object tracking in the military applications and image retrieval. The aim of this paper is to introduce an improved scale and rotation invariant algorithm based on the local feature for image matching demonstrating good performance in the case of intensity and blur changes. One of the important algorithms for image matching is SURF. Recent algorithms that are proposed in this field are divided into two groups. The first group have better performance than SURF but their running time have been increased. The second group reach a lower running time compared with SURF but they scarify the performance. This paper proposes a novel algorithm that has better performance than SURF with no running time overhead.

Ontology is a conceptualization of a domain into an understandable structure for human and readable format for machine that is consisting of concepts, attributes, relationships and axioms. Domain ontology is a kind of ontology which is used to represent the knowledge for a particular type of application domain. However, because of the imprecise nature of real world knowledge, fuzzy ontologies are better choices than crisp ontologies for real world semantic modeling. Fuzzy ontologies use soft logic instead of hard logic for knowledge representation. The quality of fuzzy domain ontology has a direct relation to exhaustiveness of corpus that used for creation of ontology. In this paper we propose an applicable method for exhaustive corpus collection needed for fuzzy domain ontology creation. This method comprises of Domain Model Creation and Corpus Collection by Focused Web Crawler. Finally for ontology effectiveness evaluation, we have investigated the application of fuzzy domain ontology in semantic web service description and matchmaking process.

In this paper, a speech steganography method in the wavelet domain using Indirect Least Significant Bit (ILSB) is proposed which is utilized genetic algorithm. In this method, we first calculate the Discrete Wavelet Transform (DWT) of the sample of host and secret speech signal. After that, wavelet coefficients of the secret speech signal are fitted effectively and efficiently to the host signal wavelet coefficients using a continuous genetic algorithm. In the genetic algorithm, a fitness scaling method is applied to improve the selection operator and adjustment of selection pressure. In addition, a combination of elitism, crowding replacement and incest prevention is used to provide population diversity and to avoid dominant species creation. Due to the quantization error, there are some differences between the secret signal before and after steganography. But these differences have an appropriate Gaussian noise model. We compress these differences using Huffman lossless compression method. The compression rate of such differences approach to the entropy which is derived from Shannon's first theorem. Huffman lossless compression method, cause to small noise. We these compressed differences sent along the stego signal. The experimental results show a transparent stego signal and high embedding capacity. On the other hand, these results illustrate improvement of mean, variance, skewness and kurtosis values in time and frequency domains in comparison with the three LSB, Frequency Masking (FM) and Efficient Wavelet Masking (EWM). In addition, the continuous genetic algorithm increases 10% of the number of suitable locations for embedding in average.