Institute of Electron Technology
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Detecting Password File Theft using Predefined Time-Delays between Certain Password Characters, Journal of Telecommunications and Information Technology, 2017, nr 4
Get PDFThis paper presents novel mechanisms that effectively detect password file thefts and at the same time prevent uncovering passwords. The proposed mechanism uses delay between consecutive keystrokes of the password characters. In presented case, a user should not only enter his password correctly during the sign-up process, but also needs to introduce relatively large time gaps between certain password characters. The proposed novel approaches disguise stored passwords by adding a suffix value that helps in detecting password file theft at the first sign-in attempt by an adversary who steals and cracks the hashed password file. Any attempt to login using a real password without adding the time delays in the correct positions may considered as an impersonation attack, i.e. the password file has been stolen and cracked
Synthesis and Failure Correction of Flattop and Cosecant Squared Beam Patterns in Linear Antenna Arrays, Journal of Telecommunications and Information Technology, 2017, nr 4
Get PDFThis paper deals with the synthesis of flattop and cosecant squared beam patterns using the firefly algorithm which is based on metaheuristics. This synthesis is followed by the correction of the radiation patterns when unfortunate malfunctioning of the individual elements in the array occurs. The necessary attention is given to the recovery process, with due emphasis on reduction of side lobe level, ripple and the reflection coefficient. Simulation in Matlab shows a successful employment of the firefly algorithm in producing voltage excitations of the good elements necessary for the recovered patterns. The performance of the firefly algorithm in failure correction is validated by duly comparing it with a standard benchmark
Reconfigurable Antenna Arrays with Phase-only Control in the Presence of Near-field Nulls, Journal of Telecommunications and Information Technology, 2017, nr 3
Get PDFIn this paper an effective iterative method is presented for the power synthesis of reconfigurable antenna arrays. The algorithm is suitable for arrays of arbitrary geometry, including the case where a large number of elements is involved. The reconfigurability is achieved by phase-only control, so that the excitation amplitude of each array element remains constant during the reconfiguration process. Such amplitudes may be different from one array element to the others, and they are not assigned a priori, but are optimized. Furthermore, the electric field is imposed to vanish in a number of prescribed points of the near-field region, so that a strong field reduction is obtained in a neighborhood of them
Unsupervised Phoneme Segmentation Based on Main Energy Change for Arabic Speech, Journal of Telecommunications and Information Technology, 2017, nr 1
Get PDFIn this paper, a new method for segmenting speech at the phoneme level is presented. For this purpose, author uses the short-time Fourier transform of the speech signal. The goal is to identify the locations of main energy changes in frequency over time, which can be described as phoneme boundaries. A frequency range analysis and search for energy changes in individual area is applied to obtain further precision to identify speech segments that carry out vowel and consonant segment confined in small number of narrow spectral areas. This method merely utilizes the power spectrum of the signal for segmentation. There is no need for any adaptation of the parameters or training for different speakers in advance. In addition, no transcript information, neither any prior linguistic knowledge about the phonemes is needed, or voiced/unvoiced decision making is required. Segmentation results with proposed method have been compared with a manual segmentation, and compared with three same kinds of segmentation methods. These results show that 81% of the boundaries are successfully identified. This research aims to improve the acoustic parameters for all the processing systems of the Arab speech
Search for Chelyabinsk Meteorite Fragments in Chebarkul Lake Bottom (GPR and Magnetic Data), Journal of Telecommunications and Information Technology, 2017, nr 3
Get PDFThe paper summarizes experimental efforts of the Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation (IZMIRAN) undertaken in search of the biggest part of Chelyabinsk meteorite in the bottom of lake Chebarkul, South Ural, Russia, and to estimate the ecological effects of its subsequent excavation
Advanced Inversion Techniquesfor Ground Penetrating Radar, Journal of Telecommunications and Information Technology, 2017, nr 3
Get PDFGround Penetrating Radar (GPR) systems arenowadays standard inspection tools in several application areas, such as subsurface prospecting, civil engineering and cultural heritage monitoring. Usually, the raw output of GPR isprovided as a B-scan, which has to be further processed inorder to extract the needed information about the inspectedscene. In this framework, inversescattering-based approachesare gaining an ever-increasing interest, thanks to their capabil-ities of directly providing images of the physical and dielectricproperties of the investigated areas. In this paper, some advances in the development of such inversion techniques in theGPR field are revised and discussed
Multiple-ring Circular Arrayfor Ground-Penetrating Radar Applications:Basic Ideas and Preliminary Results, Journal of Telecommunications and Information Technology, 2017, nr 3
Get PDFIn this paper, the possibility of using a multiple-ring circular array as an antenna array for Ground-Pene-trating Radar systems is investigated. The theory behind theproposed idea is presented. The preliminary numerical re-sults that are obtained suggest that the proposed congura-tion is promising. It allows achieving a wide frequency bandand low dynamic range ratio of excitations, thus simplifyingthe feeding network. Further interesting requirements maybe satised by exploiting a combination of deterministic andstochastic synthesis techniques to design the array
Compensation of Fading Channels Using Partial Combining Equalizer in MC-CDMA Systems, Journal of Telecommunications and Information Technology, 2017, nr 1
Get PDFIn this paper the performance of a partial combining equalizer for Multi-Carrier Code Division Multiple Access (MC-CDMA) systems is analytically and numerically evaluated. In the part of channel identification, authors propose a blind algorithm based on Higher Order Cumulants (HOC) for identifying the parameters representing the indoor scenario of Broadband Radio Access Networks (BRAN A) channel model normalized for MC-CDMA systems. Theoretical analysis and numerical simulation results, in noisy environment and for different Signal to Noise Ratio (SNR), are presented to illustrate the performance of the proposed algorithm in the one hand, and the other hand the impact of partial combining equalizer on the performance of MC-CDMA systems
Design Exploration of AES Accelerators on FPGAs and GPUs, Journal of Telecommunications and Information Technology, 2017, nr 1
Get PDFThe embedded systems are increasingly becoming a key technological component of all kinds of complex technical systems and an exhaustive analysis of the state of the art of all current performance with respect to architectures, design methodologies, test and applications could be very interesting. The Advanced Encryption Standard (AES), based on the well-known algorithm Rijndael, is designed to be easily implemented in hardware and software platforms. General purpose computing on graphics processing unit (GPGPU) is an alternative to recongurable accelerators based on FPGA devices. This paper presents a direct comparison between FPGA and GPU used as accelerators for the AES cipher. The results achieved on both platforms and their analysis has been compared to several others in order to establish which device is best at playing the role of hardware accelerator by each solution showing interesting considerations in terms of throughput, speedup factor, and resource usage. This analysis suggests that, while hardware design on FPGA remains the natural choice for consumer-product design, GPUs are nowadays the preferable choice for PC based accelerators, especially when the processing routines are highly parallelizable