Design of optimal controllers satisfying performance criteria of minimum tracking error and disturbance level for an interval system using a multi-objective evolutionary approach is proposed in this paper. Based on a worst-case design philosophy, the design problem is formulated as a minimax optimization problem, subsequently solved by a proposed two-phase multi-objective genetic algorithm (MOGA). By using two sets of interactive genetic algorithms where the first one determines the maximum (worst-case) cost function values for a given set of controller parameters while the other one minimizes the maximum cost function values passed from the first genetic algorithm, the proposed approach evolutionarily derives the optimal controllers for the interval system. To suitably assess chromosomes for their fitness in a population, root locations of the 32 generalized Kharitonov polynomials will be used to establish a constraints handling mechanism, based on which a fitness function can be constructed for effective evaluation of the chromosomes. Because of the time-consuming process that genetic algorithms generally exhibit, particularly the problem nature of minimax optimization, a parallel computation scheme for the evolutionary approach in the MATLAB-based working environment is also proposed to accelerate the design process.

A general method for generating multiple two-dimensional frequency-hopping pilot signals with limited mutual interference, for propagation channel estimation in time and frequency with equidistant sampling, is presented. Each pilot signal uses a different generic frequency-hopping pilot pattern that is repeated in frequency domain, with repetition period equal to the desired sampling interval in frequency domain. Some interesting special cases of the general construction are considered as well. The practical applicability and usefulness of the proposed solution are demonstrated by the numerical evaluation of a set of frequency-hopping pilot patterns in a typical multi-cell scenario of the future evolved third generation cellular systems.

Quasi-orthogonal Space Time Block Code (STBC) was designed to provide full transmission rate when using more than two antennas. However, it cannot have a full diversity gain because of the interference resulted from its quasi orthogonality property. In order to achieve full diversity from quasi-orthogonal STBC, the interference can be removed by a Simple Correlation Canceling (SCC) algorithm which improves a system performance significantly. However, the SCC algorithm has a disadvantage that produces noise enhancement, thereby resulting in performance degradation. Accordingly, without increasing an extra system complexity, an unequal power allocation scheme in a transmitter is proposed to achieve a better system performance than the conventional STBC system using the SCC algorithm. Also, the unequal power allocation scheme enables a receiver to use a simple decoding procedure that does not produce noise enhancement.

In this letter, we elucidate the ergodic capacity of multiple-input multiple-output (MIMO) systems with M-ary phase-shift keying (MPSK) modulation and time-multiplexed pilots in frequency-flat Rayleigh fading environment. With linear minimum mean square error (LMMSE) channel estimation, the optimal pilots design is presented. For mathematical tractability, we derive an easy-computing closed-form lower bound of the channel capacity. Based on the lower bound, the optimal power allocation between the data and pilots is also presented in closed-form, and the optimal training length is investigated by numerical optimization. It is shown that the transmit scheme with equal training and data power and optimized training length provides suboptimal performance, and the transmit scheme with optimized training length and training power is optimal. With the latter scheme, in most situations, the optimal training length equals the number of the transmit antennas and the corresponding optimal power allocation can be easily computed with the proposed formula.

This letter proposes a compact multi-layered bandpass filter exhibiting left-handed and right-handed behaviors in its passband. This filter has a greatly expanded passband from 1.61 GHz to 4.16 GHz (88.4% bandwidth) with a maximum ripple of 1.2 dB and well-suppressed out-of-passbands with transmission zeros at 1.15 GHz and 4.52 GHz. The physical mechanisms are studied with FEM-based full-wave simulations, equivalent circuit analysis and careful experiments.

A systematic approach to the analysis and design of a bi-directional Cuk converter for the cell voltage balancing control of a series-connected lithium-ion battery string is presented in this paper. The proposed individual cell equalizers (ICE) are designed to operate at discontinuous-capacitor-voltage mode (DCVM) to achieve the zero-voltage switching (ZVS) for reducing the switching loss of the bi-directional DC/DC converters. Simulation and experimental results show that the proposed battery equalization scheme can not only enhance the bi-directional battery equalization performance, but also can reduce the switching loss during the equalization period. Two designed examples are demonstrated, the switch power losses are significantly reduced by 52.8% from the MOSFETs and the equalization efficiency can be improved by 68-86.9% using the proposed DCVM ZVS battery equalizer under the specified cell equalization process. The charged/discharged capacity of the lithium-ion battery string is increased by using the proposed ICEs equipped in the battery string.

This study presents an N-gram adaptation technique when additional text data for the adaptation do not exist. We use a language modeling approach to the information retrieval (IR) technique to collect the appropriate adaptation corpus from baseline text data. We propose to use a dynamic interpolation coefficient to merge the N-gram, where the interpolation coefficient is estimated from the word hypotheses obtained by segmenting the input speech. Experimental results show that the proposed adapted N-gram always has better performance than the background N-gram.

This paper treats transmission characteristics of periodic structure of ferrite gyrator circuit with both theory and experiment, which is loaded into usual distributed constant line with and without lumped capacitor. Following three types of periodic structure of gyrator circuit are proposed: basic structure of periodic gyrator circuit, quasi-LH gyrator circuit with series capacitance loading, and quasi-LH gyrator circuit with parallel capacitance loading. Moreover, replacing the parallel capacitance with a resistance, a periodic structure of isolator circuit is proposed. Scattering parameters of gyrator circuit are derived with help of equivalent circuit model. Left handed transmission behavior of backward wave is discussed from dispersion curves. Experiments were undertaken using periodic structure of dielectric microstrip line and gyrator circuit fabricated on the ferrite substrate. Experimental results having wide band nonreciprocal characteristics are discussed with theory.

It was previously shown that the number of array elements must exceed the number of sources for multiple target direction of arrival (DOA) tracking. This is clearly not practical for code-division multiple access (CDMA) communications since the number of mobile users is very large. To overcome the restriction, adaptive angle tracking approaches employing the code-matched filters and parallel Kalman/H∞ algorithms are presented in this paper. The proposed approaches are applied to the base station of a mobile communication system. Different from Kalman prediction algorithm which minimize the squared tracking error, the adaptive H∞ filtering algorithm is a worst case optimization. It minimizes the effect of the worst disturbances (including modeling error of direction matrix models and array structure imperfection, process noise, and measurement noise). Hence, the difficult problem of tracking the crossing mobiles can be successfully handled by using the code-matched filters. Computer simulation is provided for illustrating the effectiveness of the adaptive angle tracking approaches.

Vibration characteristic of electromagnetic relay (EMR), including modal and frequency response are important for increasing operational reliability in mechanical environment. The switching contact system, as function execution component of EMR, is the important parts in this product. This paper presents a dynamic model of contact system by introducing Hertz contact theory, and discusses weakly nonlinear oscillation character. Quasilinear simulation analysis using by finite element analyzing software-NASTRAN is investigated. The factors affecting contact vibration characteristic are determined. Finally, theory analysis and simulation results are verified by the vibration test. The model starts from a typical contact system of EMR, but the approach can be applied to other switching electro-mechanical devices.

Efficient real-time contents distribution services on the Internet are only possible by suppressing the influence of packet losses. One solution for UDP transmission is the use of Forward Error Correction (FEC) based on Reed-Solomon codes. However, a more efficient method is required since this causes the increase of network traffic and includes the weakness to burst packet losses. In this paper, we propose a data recovery method that generates redundant data with the combination of Reed-Solomon codes and convolution of neighboring blocks. We realize the small amount of redundancy and the high reliability in data transmission compared with using only Reed-Solomon codes in the environment that burst packet losses are occurred frequently. We implement proposal method into the network bridge and confirm its efficiency from the viewpoint of data reconstruction from burst packet losses.

Similar to algebraic decoding schemes, the (23, 12, 7) Golay code can be decoded by applying the step-by-step decoding algorithm. In this work, a modified step-by-step algorithm for decoding the Golay code is presented. Logical analysis yielded a simple rule for directly determining whether a bit in the received word is correct. The computational complexity can be reduced significantly using this scheme.

A probability density distribution of the envelope of maximal-ratio combiner output in a very generally distributed fading channel is derived. The derived formula has a series expanded form consisting of positive terms of the well-known m-distribution and is practical for numerical calculation, approximation and analysis.

In this letter, we propose a symbol repetition technique combined with parallel channel encoding for multiband orthogonal frequency division multiplexing systems with ultra wideband channels. It can resolve timing asynchronous cochannel interference from another simultaneously operating piconet. Our simulation results demonstrate that the proposed scheme can effectively reduce the effect of the interference.

The optical network represents a promising approach to achieve a scalable backbone network. In backbone networks, survivability is important because high volumes of traffic are prone to be damaged by faulty equipment. Various design methods for survivable optical networks have been proposed, although none considering the simultaneous maintenance of multiple transmission lines has been proposed to our knowledge. This paper proposes a design method for survivable optical networks where multiple transmission lines sharing common transmission equipment may suffer simultaneous damage, due to failure in the transmission equipment. Moreover, two transmission lines can be maintained simultaneously. A mathematical programming model to obtain the optimum lightpath arrangement is presented assuming three kinds of lightpath recovery schemes. The relation between the required transmission line capacity and the combination pattern of two transmission lines that undergo maintenance is clarified using the proposed design method.

In this paper an analysis of component and system reliability for lattice systems is proposed when component failures are not statistically independent. We deal the case that the failure rate of a component depends on the number of the adjacent failed components. And we discuss the maintainability of the system when a failed component is replaced by a spare component. At first we discuss the approximated reliability of each component. Then we estimate the mean number of failed components. Furthermore, the system reliability is approximated by using the component reliability.

In this paper, the separation of heat generation and heat transfer related to temperature rise of silver palladium contact was investigated experimentally in order to predict the temperature rise of contact by the use conditions such as voltage range between 25 to 40 V, current range between 3.2 to 5.0 A and silver palladium alloy (AgPd) materials. Firstly, relationship between temperature rise of contact and supply power was discussed. The effects of heat generation and heat transfer on temperature rise were separated and quantified by least squares method. Secondly, effects of durations and integral powers of bridge and arc on temperature rise were also discussed by changing supply power. Results show that the integral power of the bridge increases when supply power increases. As the supply power increases, integral power of arc also increases. The temperature rise is dominated by integral power of bridge. Remarkable difference of bridge duration can not be seen in the five materials (AgPd30, AgPd40, AgPd50, AgPd70 and Pd). The supply power is increased, arc duration gets longer. As weight percent of Pd content increases, the effect of supply power on arc duration becomes larger. Consequently, the integral power of arc increases. This study is a basic consideration to realize methods predicting temperature rise of contact.

An H.264-based selective FGS coding scheme is proposed. It selectively uses the interframe-prediction data inside the enhancement-layer only when those data can significantly reduce the temporal-redundancies. Since this minimizes the drift effects, the overall coding efficiency is improved. Simulations show that average PSNR of the proposed scheme is higher by 1-3 dB and 3-5 dB than those of the H.264-based FGS and the MPEG-4 video FGS profile, respectively.

In this paper, we propose a new robust model predictive control (MPC) technique for linear parameter varying (LPV) systems expressed as linear systems with feedback parameters. It is based on the minimization of the upper bound of finite horizon cost function using a new parameter dependent terminal weighting matrix. The proposed parameter dependent terminal weighting matrix for norm-bounded uncertain models provides a less conservative condition for terminal inequality. The optimization problem that satisfies the terminal inequality is solved by semi-definite programming involving linear matrix inequalities (LMIs). A numerical example is included to illustrate the effectiveness of the proposed method.

To clarify the transmission characteristics and near magnetic field on the angle pattern for the parallel transmission lines, the authors investigate how influence the angled pattern on the transmission lines by experiment and calculation. The angled patterns on the transmission lines are straight, right angle and curve. It shows that the suppression of EMI radiation at the angled pattern on the parallel transmission lines of the magnetic head is essential. In addition, it is suggested that angle pattern might be one of cause for the signal distortion and specific EMI radiation at high frequency.