نشریه صنایع الکترونیک
سال پنجم شماره 3 (پیاپی 18، پاییز 1393)

E-commerce is outcome of the development and globalization of information technology in all areas of human life. Data security and privacy play an important role in e-commerce. Biometric technology as a solution can be used for authentication in e-commerce transactions. But the theft of biometric information such as fingerprint is a challenging problem. Sending a confidential data with the fingerprint image can avoid this situation. In this paper, the RSA algorithm and the Diffie-Helman algorithm are used to encrypt the confidential data. Then the encrypted date is hidden in a fingerprint image. SIFT algorithm is applied to extract corresponding points in the two data sets from the original images and Stego image (already information embedded image) and performance of this descriptor in fingerprint matching is investigated. Results showed the SIFTalgorithm matched 88.23% and 96.15%, by applying the RSA algorithm and Diffie-Helman algorithm, respectively. Therefore, the steganography of a confidential data in the fingerprint image provides access of the authorized people to biometric information and the quality of fingerprint image does not change.

In this paper, a novel secure active RFID system at 2.4 GHz is designed and implemented for vehicle tracking applications, which is compatible with IEEE 802.15.4 standard. In this system, a windows based user interface is developed to do vehicle tracking. By clicking on a button in this graphical user interface, 8 vehicles presented in the surroundings (not far than 60 m from RFID reader) are identified within 31 msec. In the development of this software, both the layering and abstraction ideas are utilized, leading to the extensibility and error propagation reduction of the software. Besides, implementation by the object oriented approach has resulted in the simplicity of the development, data security and acceleration in debugging and updating.

Networked Control Systems (NCSs) are used to control a remote process via data communication network. Two major drawbacks in these systems are network time delay and network packet loss. Fuzzy logic controllers due to their nonlinear inherent could be a good solution choice for controlling processes. In this paper, fuzzy logic controller can be adapted using a nonlinear system such as neural network. Fuzzy logic controller rules table rotates based on a nonlinear relation of network time delay estimation. The value of rotation was calculated using a neural network. Unlike some other similar works, this paper uses Markov chain to model packet loss instead of Bernoulli modeling. This method has the advantage of considering packet loss events consecutively. Simulation results show that if the network time delay is about 600 ms, then in the case that packet loss occurs consecutively with rate of 70%, the index of proposed controller performance is improved about 3 and 7 times in comparison with performance index of Smith predictor and fuzzy logic controller, respectively.

This paper presents simulation results of satellite launch vehicle tracking with Monopulse Track method. Monopulse system is Amplitude-Amplitude. In other words, position determination of antenna for satellite launch vehicle precise tracking with monopulse method is done. Target has maneuvered in the paper and trajectory changes during the tracking; Consequently probability of error is more than targets such as satellite that have steady orbit; These targets surveyed in the similar previous works. At the first, we have the data of supposed trajectory of satellite launch vehicle. The amount of offset of antenna's position with the trajectory is indicator of prime error antenna tracking which that is the input of monopulse algorithm and the offset is corrected with the proposed method. Simulation results demonstrate good performance of the proposed method for satellite launch vehicle tracking.

In this study, a vision-based algorithm for landing unmanned helicopter is developed to increase the accuracy of pose estimation. In the current algorithm, the reference image of helipad has been matched with the image acquired by the UAV mounted camera using SIFT technique to associate between the corresponding feature points of these two images. Then, the corresponding features are used to estimate the pose of the helicopter relative to the helipad using decomposition of Homography matrix. Applying a sensitivity analysis to pose estimation accuracy, we found the important role of spatial distribution of features. So, a method is suggested for choosing the best features in Homography matrix extraction. Moreover, a proper landmark is designed for helipad such as its features have an inherently appropriate local distribution. This method is assessed implementation in MATLAB software via the real images and different scenarios designed in VRML environment are used. The results of proposed algorithm on produced images from different landmarks, improved the pose estimation error about 30 percent.

Proposed is a novel method for stabilizing phase center location variation (PCLV) of Log periodic antennas based on modifying excitation current phase (ECPh). To validate this technique, an ultra wideband planar log-periodic dipole array antenna (PLPDA) was designed for operating in L and S bands (1-4GHz) with 12 dipoles. Defected microstrip structure (DMS) and microstrip meander structure (MMS) investigated for ECPh linearization and so, MMS was used to modify ECPh as the best structure with highest dynamic range based on limited length between adjacent elements and antenna impedance matching. Finally, modified PLPDA (MPLPDA) was designed and fabricated with 6 MMS structures without any changes in antenna dimensions. Measurement and simulation results show that radiation patterns of both antennas have a good conformity while the PCLV of MPLPDA is stabilized. Moreover, MPLPDA has a -10dB bandwidth of 4.5 GHz.

In this article we designed and simulated a serially coupled quintuple microring resonator for building optical filters with desirable characteristics. For modeling this filter SFG method is used. Proposed filter has improved features in compare to common triple and quadruple ring resonator. It is shown that with this design, desired filter spectrum response shape coefficient and its free spectral range is increased while its interstitial resonance is decreased. It is depicted that using five similar mirroring resonator shape factor coefficient of 0.84, FSR of 100 GHz are achievable for the designed filter. For increasing the FSR, Vernier ring resonators is proposed. It is illustrated that by designing the 5 serially coupled Vernier rings with optimum parameters the narrow band filter can be achieved with FSR of 1000 GHz and shape factor coefficient of 0.8.

In this paper two methods are presented for DOA estimation of narrow band and coherent signals. Advantages of this method with compare to another methods are Simple calculation, highly accurate for low signal-to-noise-ratio (SNR) and low requirement sensor array. this method is used for coherent signal and also it can used for know algorithms such as MUSIC, Root-MUSIC, ESPRIT which just applied for DOA estimation of narrow band and noncoherent signals. main purpose in the presented methods is calculation of mean cross correlation vectors between receiver signals on sensor array and out of them. In this paper have been compared the presented method to FBSS and FOSS method together by Matlab.