In this paper the attention is focused on the numerical study of hyperchaotic 2D-scroll attractors via the Adomian decomposition method. The approach, which provides series solutions of the system equations, is first applied to weakly-coupled Chua's circuits with Hermite interpolating polynomials. Then the method is successfully utilized for achieving hyperchaos synchronization of two coupled Chua's circuits. The reported examples show that the approach presents two main features, i.e., the system nonlinearity is preserved and the chaotic solution is provided in a closed form.

In this paper, we propose two techniques to solve the nonlinear constrained optimization problem in large scale mesh-interconnected system. The first one is a diagram-method-based decomposition technique which decomposes the large scale system into some small subsystems. The second technique is a projected-Jacobi-based parallel dual-type method which can solve the optimization problems in the decomposed subsystems efficiently. We have used the proposed algorithm to solve numerous examples of large scale constrained optimization problems in power system. The test results show that the proposed algorithm has computational efficiency with respect to the conventional approach of the centralized Newton method and the state-of-the-art Block-Parallel Newton method.

For point-to-point mobile visual communications, layered video has been utilized to adapt to time-varying channel capacity over noisy environments. From the perspective of the HVS (Human Visual System), it is necessary to minimize the loss of visual quality by specifically maintaining the throughput of visually important regions, objects and so on. Utilizing the prioritized bitstreams generated according to each layer, the throughput can be improved for given channel statistics. In this paper, we define the transmission gain and measure the improved performance when the throughput of ROI (Regions Of Interest) is increased relative to visually unimportant regions over a capacity limited mobile channel.

The default server strategy is commonly used to manage the location and state of mobile hosts in cellular networks. With this strategy, connections can be established after the client obtains the location information of the mobile host by querying the default server. Unfortunately, the communication cost increases if the query requests are frequent and the distance between the default server and the client is long. Still more, no connection to a mobile host can be established when the default server of the destination mobile host fails. These problems can be solved by replicating the default servers and by letting the nearest replicated default server process the query request which is sent from a client [9]. It is important to allocate replicated default servers efficiently in networks and determine the number of replicated default servers. In this paper, we suggest and evaluate a default server replication strategy to reduce communication costs and to improve service availabilities. We consider optimal replication degree as well as location for replicating the default servers in n-grid and tree networks.

In this paper, we shall describe about a refined theory based on the concept of set-valued operators, suitable for available operation of extremely complicated large-scale network systems. The deduction of theory is accomplished in a weak topology introduced into the Banach space. Fundamental conditions for availability of system behaviors of such network systems are clarified, as a result, in a form of fixed point theorem for system of set-valued operators.

In this article, the security of double-block-length hash functions with the rate 1 is analyzed, whose compression functions are composed of block ciphers with their key length twice larger than their block length. First, the analysis by Satoh, Haga and Kurosawa is investigated, and it is shown that there exists a case uncovered by their analysis. Second, a large class of compression functions are defined, and it is shown that they are at most as secure as those of single-block-length hash functions. Finally, some candidate hash functions are given which are possibly optimally collision-resistant.

The present paper introduces a new construction of a class of binary periodic sequence set having a zero-correlation zone (hereinafter binary ZCA sequence set). The cross-correlation function and the side-lobe of the auto-correlation function of the proposed sequence set is zero for the phase shifts within the zero-correlation zone. The present paper shows that such a construction generates a binary ZCA sequence set by using a cyclic difference set and a collection of mutually orthogonal complementary sets.

The pseudo-transient method is discussed in this paper as one of practical methods to find DC operating points of nonlinear circuits when the Newton-Raphson method fails. The mathematical description for this method is presented and an effective pseudo-transient algorithm utilizing compound pseudo-elements is proposed. Numerical examples are demonstrated to prove that our algorithm is able to avoid the oscillation problems effectively and also improve the simulation efficiency.

In this paper, a multistage parallel interference canceller (MPIC) with multiple-beam reception for a DS-CDMA system is proposed to suppress multiple access interference (MAI) effectively. Its aim is to reduce the computational complexity of the conventional MPIC cascaded with an adaptive array antenna. It employs multiple fixed beams based on phased array and selects suitable beams to demodulate the transmitted signal of each user. Then it suppresses residual interference signals by the MPIC cascaded with multiple-beam receiver. Its bit error rate (BER) performance is evaluated by computer simulations assuming an uplink single-chip-rate multiple-spreading-factor DS-CDMA system over both exponentially decaying 5-path and equal average power 2-path Rayleigh distributed channels. When there are 16 users in an 120-sectored single cell, the proposed receiver with 6-element array antenna and 2-stage MPIC shows better or comparable BER performance compared with that of the conventional receiver. Moreover, the proposed receiver with 8 beams can reduce the number of complex multiplications to about 40% of that of the complexity-reduced conventional receiver over 5-path channels.

In this paper, we present a new low-cost concurrent error detection (CED) S-Box architecture for the Advanced Encryption Standard (AES). Because the complexity and the nonlinearity, it is difficult to develop error detection algorithms for the S-Box. Conventionally, a parity checked S-Box is implemented with ROM (read only memory). In some applications, for example, smart cards, both chip size and fault detection are demanded seriously. ROM-based parity checking cannot meet the demands. We propose our CED S-Box (CEDSB) architecture for two reasons. The first is to design a S-Box without ROM. The second is to obtain a compact S-Box with real time error detection. Based on the composite field, we develop the CEDSB architecture to implement the fault detection for the S-Box. The overhead of the CED for the S-Boxes in GF((24)2) and in GF(((22)2)2) are 152 and 132 NAND gates respectively. The amount of extra gates used for the CEDSB is nearly equal to that of the ROM-based CED S-Box (131 NAND gates). The chip area of the ROM-based CED S-Box, the CEDSBs in GF((24)2), and in GF(((22)2)2) are 2996, 558, and 492 NAND gates separately. The chip area of the CEDSB is more compact than a ROM-based CED S-Box.

Compound noun segmentation is a key component for Korean language processing. Supervised approaches require some types of human intervention such as maintaining lexicons, manually segmenting the corpora, or devising heuristic rules. Thus, they suffer from the unknown word problem, and cannot distinguish domain-oriented or corpus-directed segmentation results from the others. These problems can be overcome by unsupervised approaches that employ segmentation clues obtained purely from a raw corpus. However, most unsupervised approaches require tuning of empirical parameters or learning of the statistical dictionary. To develop a tuning-less, learning-free unsupervised segmentation algorithm, this study proposes a pruning-based unsupervised technique that eliminates unhelpful segmentation candidates. In addition, unlike previous unsupervised methods that have relied on purely character-based segmentation clues, this study utilizes word-based segmentation clues. Experimental evaluations show that the pruning scheme is very effective to unsupervised segmentation of Korean compound nouns, and the use of word-based prior knowledge enables better segmentation accuracy. This study also shows that the proposed algorithm performs competitively with or better than other unsupervised methods.

This paper proposes a 15-bit 10-MS/s pipelined ADC based on the incomplete settling principle. The traditional complete settling stage is improved to the incomplete settling structure through dividing the sampling clock of the traditional stage into two parts for discharging the sampling and feedback capacitors and completing the sampling, respectively. The proposed ADC verifies the correction and validity of optimizing ADCs' conversion speed without additional power consumption through the incomplete settling. This ADC employs scaling-down scheme to achieve low power dissipation and utilizes full-differential structure, bottom-plate-sampling, and capacitor-sharing techniques as well as bit-by-bit digital self-calibration to increase the ADC's linearity. It is processed in 0.18 µm 1P6M CMOS mixed-mode technology. Simulation results show that 82 dB SNDR and 87 dB SFDR are obtained at the sampling rate of 10 MHz with the input sine frequency of 100 kHz and the whole static power dissipation is 21.94 mW.

The location information of ubiquitous objects is one of the key issues for context-aware systems. Therefore, several positioning systems to obtain precise location information have been researched. However, they have scalability and flexibility problems because they need completely configured space with a large number of sensors. To avoid the problems, we proposed a self-organizing location estimation method that uses ad hoc networks and Self-Organizing Maps and needs no prepared space with a large number of sensors. But, as in other similar precise localization methods, the proposed method needs advanced distance measurements unavailable to conventional wireless communication systems. In this paper, the self-organizing location estimation method's modification for distance measurement that uses received signal strength available to conventional wireless communication systems but which fluctuates uncertainly, is described and location estimation accuracy with the modified method is shown.

In the reverse link of orthogonal frequency division multiplexing (OFDM)/ space division multiple access (SDMA) systems, each receive antenna of a base station receives a multiplexed version of signals transmitted from users, where the transmitted signals have individual amounts of frequency offset. Therefore, a frequency offset compensation scheme which is different from those used in general OFDM systems is required. For this requirement, frequency offset compensation schemes using the feedback transmission from the base station to user terminals have been proposed for multiuser OFDM systems. These schemes work with good precision when the feedback information is correct and is transmitted without errors. However, when the offset information is incorrectly received at user terminals, the frequency offset is not accurately compensated for. In OFDM/SDMA systems, one user is enough for causing inter-carrier interference to all users. Therefore, a frequency offset compensation scheme without feedback transmission is sometimes preferable. In this paper, we propose a frequency offset compensation scheme without feedback transmission. To compensate for frequency offset in every transmitted signal, the multiplexed received signals must be separated into each user's component before the offset compensation. Thus, we adopt the principle of the parallel interference cancellation (PIC). By employing PIC, the received signals can be separated before the offset compensation. Thus, the frequency offset of every user's signal can be compensated for. Simulation results show the bit error rate performance of the proposed scheme attains almost the same as that of the conventional scheme using the feedback transmission without errors.

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.

In this paper, we present a resource monitoring and selection method for rapid turnaround grid applications (for example, within 10 seconds). The novelty of our method is the distributed evaluation of resources for rapidly selecting the appropriate idle resources. We integrate our method with a widely used resource management system, namely the Monitoring and Discovery System 2 (MDS2), and compare our method with the original MDS2 in terms of the performance and the scalability. The performance is measured using a 64-node cluster of PCs and the scalability is analyzed using a theoretical model and the measured performance. The experimental results show that our method reduces the resource selection time by 82%, as compared with the original MDS2. The scalability analysis also indicates that our method can keep the resource selection time within 1 second, up to 500 nodes in local-area-network (LAN) environments. In addition, some simulation results are presented to estimate the impact of our method for wide-area-network (WAN) environments.

This letter develops theoretical analysis of the normalized LMS algorithm (NLMSA) for use in complex-domain adaptive filters in the presence of impulse noise at filter input. We propose a new "stochastic" model for such impulse noise, and assume that filter reference input process is a white process, e.g., digital QAM data, White & Gaussian process, etc. In the analysis, we derive a simple difference equation for mean square tap weight misalignment (MSTWM). Experiment is carried out to demonstrate effectiveness of the NLMSA in robust filtering in the presence of the impulse noise at the filter input. Good agreement between simulated and theoretically calculated filter convergence, in a transient phase as well as in a steady-state, proves the validity of the analysis.

This paper introduces a novel MIMO (Multiple Input Multiple Output) communication system having orthogonal dual polarization diversity branches. We have designed a dual polarized circular patch antenna which has two orthogonal polarization ports such as vertical polarization (V) and horizontal polarization (H) on its metal surface. This design makes it works as two independent antennas in multipath environments. By using two dual polarized antennas at both the transmitter and receiver, we designed a dual-polarization 44 MIMO experiment system. This system can be used to investigate the performance of various MIMO transmission methods as well as the performance of adaptive algorithms in indoor multipath environments. To investigate the performance of our experiment system, we carried out a number of MIMO transmission experiments such as space-time-coded transmission having two parallel streams and MIMO eigenmode transmission. We will show the results of those experiments and discuss the advantages of using polarization diversity in MIMO communication system for next generation broadband wireless communication.

A novel structure for a frequency-independent steerable composite right/left-handed (CRLH) leaky wave (LW) antenna in the millimeter-wave band is proposed. This has the advantages of wide beam scanning and low profile, and is a suitable structure for mass-production. The proposed antenna has features wherein a movable dielectric slab is placed above the CRLH LW antenna, and the radiation angle can be steered by changing the distance between the slab and the antenna using compact actuators. Moreover, slots are added to the antenna to control the aperture amplitude distribution of the array antenna in order to enhance aperture efficiency. A prototype CRLH LW antenna has been fabricated with these slots, and backward-to-forward beam scanning characteristics at 76 GHz have been demonstrated successfully by measurement. A wide scanning angle from 73 to 114 deg. has been achieved experimentally. The aperture efficiency is 25.3%.

In this paper, we propose to employ an extension to the natural gradient algorithm for robust Independent Component Analysis against outliers. The standard natural gradient algorithm does not exhibit this property since it employs nonrobust sample estimates for computing higher order moments. In order to overcome this drawback, we propose to use robust alternatives to higher order moments, which are comparatively less sensitive to outliers in the observed data. Some computer simulations are presented to show that the proposed method, as compared to the standard natural gradient algorithm, gives better performance in the presence of outlying data.