Most current speech recognition systems are based on Hidden Markov Model (HMM) using Viterbi search in decoding stage. Whereas such algorithm is in terms of dynamic programming, it consists of many computations with increasing number of reference words. This paper presents a novel method called HGSCA computing likelihood measurement between an unknown input pattern and a reference model based on a synergy between HMM and Genetic Algorithm (GA) in a parallel form by Stochastic Cellular Automata (SCA). The HGSCA algorithm is compared with the Viterbi algorithm from the “recognition time” and “recognition error” view points. Experimental results show although HGSCA and Viterbi algorithms are very close in recognition accuracy, the HGSCA is so faster than the Viterbi algorithm.
Although the round-off noise is normally small, it might accumulate and significantly degrade the output quality in most computationally intensive emerging applications such as FFT calculation in data communication protocols or neural networks. A new hardware-friendly error-tunable round-off method is introduced. The most important feature of this new method is that it can provide acceptable and arbitrary selectable accuracies along with different hardware implementation costs.
Implantable middle ear hearing devices (IMEHDs) have been developed at several countries. Some devices can be selected rechargeable battery for long-term implant. In South Korea, a kind of IMEHD with rechargeable battery and a pillow type wireless charger have been developed. The charger includes several coils surrounding user's head in sleep. However, this device should excessively consume power due to driving all primary coils. Especially, needless exposure to magnetic field generated from uncoupled primary coils may induce bio-hazards. Therefore, a method reducing the body exposure to electromagnetic field was proposed as decreasing the emitted total magnetic flux during charge process.
The current-voltage characteristics of a PtSi/p-Si Schottky barrier diode was measured at the temperature of 85K and from the forward bias region of the I-V curve, the electrical parameters of the diode were measured by three methods. The results obtained from the two methods which considered the series resistance were in close agreement with each other and from them barrier height (Φb), ideality factor (n) and series resistance (Rs) were found to be 0.2045eV, 2.877 and 14.556KΩrespectively. By measuring the I-V characteristics in the temperature range of 85-136K the electrical parameters were observed to have strong dependency on temperature. The increase of barrier height and decrease of ideality factor with increasing temperature is attributed to the existence of barrier height inhomogeneities in the silicide-semiconductor structure.
A compact and broadband Wilkinson balun design incorporating three metamaterial phase shifting transmission lines (MTM-PSTLs) is proposed in this study. The two quarter wavelength lines generally used in a Wilkinson divider are replaced by -90° and +90° MTM-PSTLs for the broadband balun (balun #1) and by +90° and +270° MTM-PSTLs for the compact balun (balun #2). The characteristic impedance of the MTM-PSTLs is 70.7Ω. To improve isolation characteristics at output ports, a +180° MTM-PSTL with a characteristic impedance of 50Ω is connected in series with two 50Ω resistors between the two output ports. The designed baluns have the same size. The measured differential output phase bandwidths (180°± 10°) are 340MHz (55%) (445 - 785MHz) for balun #1 and 62MHz (30%) (174 - 236MHz) for balun #2.
A new LC quadrature voltage-controlled oscillator (LC-QVCO), made with direct coupling of two CMOS LC-VCOs, is presented. In the proposed circuit two identical cross-connected LC-VCOs are coupled together by directly connecting the bulk of the cross-connected transistors of one VCO to the bulk of the MOS varactors of the other VCO in such a way no extra devices are needed for coupling. Thus, no extra noise sources and power consumption are added to the core VCOs and results in high performance of QVCO. A Linear analysis of the circuit and the result of simulation in a 0.18µm CMOS technology are presented. The same proposed coupling scheme can be used for multiphase signal generation as well. Simulation shows the proposed QVCO can operate with supply voltage as low as 0.5V.
Fiber-optic coherence multiplexing of 10-Gsymbol/s BPSK and QPSK signals was experimentally demonstrated for the first time. Spectrum-sliced amplified spontaneous emission (ASE) was used as a light source, and two-channel signals were multiplexed. The reference signal was polarization-multiplexed with the modulated signals and transmitted through an optical fiber. At the receiver side, we successfully retrieved the channels by properly adjusting the time shift between the reference signal and the multiplexed signals using a DGD generator. BER performances of <10-4 for BPSK and <10-3 for QPSK were obtained without using error correction.
A wideband L-probe fed microstrip patch antenna is proposed. By employing L-shaped feed and modification of E-H shaped patch, an antenna with 30% impedance bandwidth (return loss -10dB) and a gain of 9.41dBi is achieved. It is shown that the wide bandwidth is caused by a two-frequency resonance. The achievable experimental 3-dB beamwidth in the azimuth and elevation are 63.53° and 51.37° respectively at the center frequency.
This paper proposes a new H∞ approach to chaos synchronization for Duffing oscillator in the presence of external disturbance. Based on Lyapunov stability theory and linear matrix inequality (LMI) formaulation, the proposed synchronization method is presented to not only guarantee asymptotical synchronization but also reduce the effect of external disturbance to an H∞ norm constraint. A simulation study is given to demonstrate the effectiveness of the proposed method.
Least Mean Square (LMS) is an effective adaptive filtering algorithm with advantages of robustness and simplicity. In this paper, we propose two new algorithms, Categorized Variable Step Size LMS (CVSSLMS) and Combined CVSSLMS (CCVSSLMS), based on the categorization of filter status. The step sizes of the proposed algorithms are dynamically updated by optimization for each state. Experiment results show that the proposed algorithms outperform conventional LMS algorithms in both simplicity and robustness.
The fuzzy vault scheme has emerged as a promising solution to the user privacy and the fingerprint template security problems. Recently, however, this scheme is shown to be susceptible to a correlation attack that finds the real minutiae using multiple vaults enrolled for different applications. To protect the fuzzy fingerprint vault from the correlation attack, we propose an approach to add chaffs in a more structured way such that distinguishing the fingerprint minutiae and the chaff points obtained from two applications is computationally hard. Experimental results show that the proposed approach achieves much secure performance than adding chaffs randomly without a significant degradation of the verification accuracy.