In many electromagnetic field problems, matrix equations were always deduced from using the method of moment. Among these matrix equations, some of them might require a large amount of computer memory storage which made them unrealistic to be solved on a personal computer. Virtually, these matrices might be too large to be solved efficiently. A fast algorithm based on a Toeplitz matrix solution was developed for solving a bordered Toeplitz matrix equation arising in electromagnetic problems applications. The developed matrix solution method can be applied to solve some electromagnetic problems having very large-scale matrices, which are deduced from the moment method procedure. In this paper, a study of a computationally efficient order-recursive algorithm for solving the linear electromagnetic problems [Z]I = V, where [Z] is a Toeplitz matrix, was presented. Upon the described Toeplitz matrix algorithm, this paper derives an efficient recursive algorithm for solving a bordered Toeplitz matrix with the matrix's major portion in the form of a Toeplitz matrix. This algorithm has remarkable advantages in reducing both the number of arithmetic operations and memory storage.
Herng-Jer LEE Chia-Chi CHU Ming-Hong LAI Wu-Shiung FENG
A method is proposed to compute moments of distributed coupled RLC interconnects. Both uniform line models and non-uniform line models will be developed. Considering both self inductances and mutual inductances in multi-conductors, recursive moment computations formulae of lumped coupled RLC interconnects are extended to those of distributed coupled RLC interconnects. By using the moment computation technique in conjunction with the projection-based order reduction method, the inductive crosstalk noise waveform can be accurately and efficiently estimated. Fundamental developments of the proposed approach will be described. Simulation results demonstrate the improved accuracy of the proposed method over the traditional lumped methods.
Masahiro YOSHIDA Yuka OBU Tatsuhiro YONEKURA
Performing a musical session via networks requires real-time interaction. There exists, however, the problem of delay between the network nodes, which causes musical sessions become an impediment. To overcome this problem, we have proposed a new protocol for musical session called Mutual Anticipated Session (M.A.S.), which is a type of ensemble that controls appropriate timing of sounds. In the M.A.S, one player's performance precedes the other players', thus this performance is called a "precedent musical performance," and we call a time lapse between the players' performance as "precedent time." In the current M.A.S, it is assumed that the tempo during the performance is constant. In such a case, however, players' requirements to perform more expressively or more emotionally by varying the tempo are sacrificed. Thus, in this paper, enhancement of function that accommodates changes of the tempo by predicting tendency of it is realized. Finally we evaluate the enhancement both by system performance test and by task performance of subject experiments.
In this paper, firstly, effects of third order dispersion (TOD) on coupled pulses are analyzed. Then, averaging method is modified and proved to be an effective way for obtaining non-radiative bi-soliton solution of the TOD perturbed nonlinear Schrodinger equation (NLSE), which models a dispersion managed (DM) optical transmission system. Finally, the obtained bi-soliton evolution behavior is studied, and compared with that of uni-soliton. With the increase of average TOD, pulse velocity of bi-soliton largely deviates from that of uni-soliton. Thus, even though TOD cannot be exactly vanished in fabrication, it is suggested to compensate average TOD as low as possible.
A new hybrid method for characterizing the irregular power/ground plane pair is developed in this paper by combining the conventional eigen-mode expansion method with the new-presented inverted composition method and a simple model order reduction. By the approach, the eigen-mode expansion method can be extended to the characteristics research of the power/ground plane pair with holes. In this gridless method, ports and decoupling capacitors can be arbitrarily placed on the plane pair. The numerical example demonstrates its good validity.
Tomonori IZUMI Shin'ichi KOUYAMA Hiroyuki OCHI Yukihiro NAKAMURA
This paper presents an approach of logic mapping into LUT-Array-Based PLD where Boolean functions in the form of the sum of generalized complex terms (SGCTs) can be mapped directly. While previous mapping approach requires predetermined variable ordering, our approach performs mapping and variable reordering simultaneously. For the purpose, we propose a directed acyclic graph based on the multiple-valued decision diagram (MDD) and an algorithm to construct the graph. Our algorithm generates candidates of SGCT expressions for each node in a bottom-up manner and selects the variables in the current level by evaluating the sizes of SGCT expressions directly. Experimental results show that our approach reduces the number of terms maximum to 71 percent for the MCNC benchmark circuits.
Masahiko SAKAI Keiichirou KUSAKARI
This paper explores how to extend the dependency pair technique for proving termination of higher-order rewrite systems. In the first order case, the termination of term rewriting systems are proved by showing the non-existence of an infinite R-chain of the dependency pairs. However, the termination and the non-existence of an infinite R-chain do not coincide in the higher-order case. We introduce a new notion of dependency forest that characterize infinite reductions and infinite R-chains, and show that the termination property of higher-order rewrite systems R can be checked by showing the non-existence of an infinite R-chain, if R is strongly linear or non-nested.
Yuh-Shyan HWANG Jen-Hung LAI Ming-Chieh CHANG
Linear transformation transistor-only high-order current-mode filters are presented in this Letter. Based on the systematic design procedure, we can realize high-order current-mode filters employing switched-current technique efficiently. Only two kinds of switched-current basic cells are needed in our design to obtain simple architectures. The fifth-order Chebychev lowpass filter is designed to verify the proposed synthesis method. Simulation results that confirm the theoretical analysis are obtained.
Yasutaka OGAWA Keisuke NISHIO Toshihiko NISHIMURA Takeo OHGANE
We consider space division multiplexing in a MIMO-OFDM system for high data rate transmission. Channel estimation is very important for suppressing interference and demultiplexing signals. In a wireless LAN system such as IEEE 802.11a, only a few training symbols are inserted in each subcarrier. First, we propose a channel estimation method for a MIMO-OFDM system with two training symbols per subcarrier. The basic idea is to estimate the time-domain channel responses between the transmit and receive antennas. The array response vectors for each subcarrier are calculated by applying a fast Fourier transform to them. We then can obtain the adaptive weights to cancel the interference. We show that employing training symbols having a lower condition number of the matrix used for the channel estimation improves the estimation accuracy. Furthermore, we show the bit error rate for several signal detection schemes using the above estimated channel. It is shown that an ordered successive detection based on an MMSE criterion has excellent performance, that is, it can achieve higher-speed transmissions with a lower transmit power.
Given a graph G, we give a fast algorithm for approximating the vertex connectivity κ of G. Our algorithm delivers a minimum vertex cut of G if κ δ/2, and returns a message "κ > δ/2" otherwise, where δ denotes the minimum degree of G. The algorithm runs in O(n2(1 + min {κ2, κ/δ)) time and O(n + m) space, where n and m denote the numbers of vertices and edges in G, respectively.
Dai TAGUCHI Takaaki MANAKA Mitsumasa IWAMOTO
The polarized absorption measurement was employed to investigate the orientational order of the 4-n-4-pentyl-cyanobiphenyl (5CB) film of sub-nanometer thick. It was confirmed that this optical technique is simple but effective to observe the second orientational order parameter, S2, of the organic ultra thin film at the interface region.
The multiple space-time trellis codes (M-STTC) structure is one of the Multiple Input Multiple output (MIMO) schemes providing high transmission rate and diversity and coding gain without bandwidth expansion. In this paper, an M-STTC system is proposed wherein the transmitter employs a multiple space-time TCM for the fast fading channel and the receiver has a decoding order block, several whitening processors, STTC decoders, and interference cancellers. The proposed layered receiver adopts a whitening process instead of a minimum mean squared error (MMSE) estimator, which is widely used in the BLAST type receiver. An optimum decoding order scheme is also planned since it gives at least a 2 dB gain in the proposed system in the fast flat Rayleigh fading channel of fd Tc = 1/3 at the FER of 10-2. For an M-STTC system employing two STTCs with four transmit and receive antennas, the layered receiver with whitening process obtains a 5 dB gain over the coded layered space-time processing in the fast flat Rayleigh fading channel at the FER of 10-2.
Takamichi NAKAMOTO Hidehiko TAKIGAWA Takao YAMANAKA
A smell reproduction technique is useful in the field of virtual reality. We have developed the system called an odor recorder for reproducing the smell recorded using the odor sensing technique. We proposed the new type of the odor recorder using the inkjet devices together with a mesh heater. Droplets with tiny volume were forcibly evaporated to generate smell rapidly and reproducibly. Moreover, the mesh heater was directly connected to the sensors without plumbing tubes and the sensors were placed away from the wall of sensor cell. The recording time of the odor with high odor intensity became much shorter than that of the previous system. Then, the recipe of jasmine scent composed of benzyl acetate and Ylang Ylang was successfully determined using the proposed system.
Nari TANABE Toshihiro FURUKAWA Kohichi SAKANIWA Shigeo TSUJII
We propose a practical blind channel identification algorithm based on the principal component analysis. The algorithm estimates (1) the channel order, (2) the noise variance, and then identifies (3) the channel impulse response, from the autocorrelation of the channel output signal without using the eigenvalue and singular-value decomposition. The special features of the proposed algorithm are (1) practical method to find the channel order and (2) reduction of computational complexity. Numerical examples show the effectiveness of the proposed algorithm.
Yong XIANG Wensheng YU Jingxin ZHANG Senjian AN
This paper presents a new method for blind source separation by exploiting phase and frequency redundancy of cyclostationary signals in a complementary way. It requires a weaker separation condition than those methods which only exploit the phase diversity or the frequency diversity of the source signals. The separation criterion is to diagonalize a polynomial matrix whose coefficient matrices consist of the correlation and cyclic correlation matrices, at time delay τ= 0, of multiple measurements. An algorithm is proposed to perform the blind source separation. Computer simulation results illustrate the performance of the new algorithm in comparison with the existing ones.
Tatsuya ASAI Kenji ABE Shinji KAWASOE Hiroshi SAKAMOTO Hiroki ARIMURA Setsuo ARIKAWA
In this paper, we consider a data mining problem for semi-structured data. Modeling semi-structured data as labeled ordered trees, we present an efficient algorithm for discovering frequent substructures from a large collection of semi-structured data. By extending the enumeration technique developed by Bayardo (SIGMOD'98) for discovering long itemsets, our algorithm scales almost linearly in the total size of maximal tree patterns contained in an input collection depending mildly on the size of the longest pattern. We also developed several pruning techniques that significantly speed-up the search. Experiments on Web data show that our algorithm runs efficiently on real-life datasets combined with proposed pruning techniques in the wide range of parameters.
With the need and adoption of link aggregation where multiple links exist between two adjacent nodes in order to increase transmission capacity between them, there arise the problems of service guarantee and fair sharing of multiple servers. Although a lot of significant work has been done for single-server scheduling disciplines in the past years, not much work is available for multi-server scheduling disciplines. In this paper, we present and investigate two round robin based multi-server scheduling disciplines, which are Multi-Server Uniform Round Robin (MS-URR) and Multi-Server Deficit Round Robin (MS-DRR). In particular, we analyze their service guarantees and fairness bounds. In addition, we discuss the misordering problem with MS-DRR and present a bound for its misordering probability.
Herng-Jer LEE Ming-Hong LAI Chia-Chi CHU Wu-Shiung FENG
A new moment computation technique for general lumped R(L)C interconnect circuits with multiple resistor loops is proposed. Using the concept of tearing, a lumped R(L)C network can be partitioned into a spanning tree and several resistor links. The contributions of network moments from each tree and the corresponding links can be determined independently. By combining the conventional moment computation algorithms and the reduced ordered binary decision diagram (ROBDD), the proposed method can compute system moments efficiently. Experimental results have demonstrate that the proposed method can indeed obtain accurate moments and is more efficient than the conventional approach.
In this study, a fourth-order cumulants based iterative algorithm for blind channel equalization is introduced, which is robust with respect to the existence of heavy Gaussian noise in a channel and does not require the minimum phase characteristic of the channel. The transmitted signals at the receiver are over-sampled to ensure the channel described by a full-column rank matrix. It changes a single-input/single-output (SISO) finite-impulse response (FIR) channel to a single-input/multi-output (SIMO) channel. Based on the properties of the fourth-order cumulants of the over-sampled channel inputs, the iterative algorithm is derived to estimate the deconvolution matrix which makes the overall transfer matrix transparent, i.e., it can be reduced to the identity matrix by simple reordering and scaling. In simulation studies, both a closed-form and a stochastic version of the proposed algorithm are tested with three-ray multi-path channels, and their performances are compared with the methods based on conventional second-order statistics and higher-order statistics (HOS) as well. Relatively good results with fast convergence speed are achieved, even when the transmitted symbols are significantly corrupted with Gaussian noise.
Hideki YAGI Manabu KOBAYASHI Toshiyasu MATSUSHIMA Shigeichi HIRASAWA
Reliability-based maximum likelihood decoding (MLD) algorithms of linear block codes have been widely studied. These algorithms efficiently search the most likely codeword using the generator matrix whose most reliable and linearly independent k (dimension of the code) columns form the identity matrix. In this paper, conditions for omitting unnecessary metrics computation of candidate codewords are derived in reliability-based MLD algorithms. The proposed conditions utilize an order relation of binary vectors. A simple method for testing if the proposed conditions are satisfied is devised. The method for testing proposed conditions requires no real number operations and, consequently, the MLD algorithm employing this method reduces the number of real number operations, compared to known reliability-based MLD algorithms.