bluuebunny/crossref_metadata_2025_split huggingface dataset:
Performance of an adaptive viterbi decoder employing respective‐state channel estimation
Authors: Kubo Hiroshi , Murakami Keishi , Fujino Tadashi 
Published: July 2007

AbstractThis paper discusses a performance of an adaptive Viterbi decoder, which performs the carrier recovery and the Viterbi decoding simultaneously. the authors have already considered the combined maximum‐likelihood sequence estimator (MLSE), according to trellis combined equalization and the Viterbi decoding and showed that the bit‐error rate in the fading environment can be improved by applying channel estimation respecitvely for states of the Viterbi algorithm. the adaptive Viterbi decodere discussed in this paper corresponds to the combined MLSE in the case of no intersymbol interference and and easily be extended to the case of the diversity reception.First, the square Euclidean distance is derived approximately by combining the channel estimation by the least mean squares (LMS) and MLSE, and it is shown that the adaptive Viterbi decoder can perform the diversity combining without carrier phase information, with only a little performance degradation compared to the ideal Viterbi decoding with known carrier phase. Then, by a computer simulation, the results of analysis and the numerical calculation are confirmed and the proposed adaptive Viterbi decoder is shown to be effective in the carrier frequency offset and fading environment.
Error spectrum shaping in two‐dimensional digital filters
Authors: Hinamoto Takao , Karino Shuji , Kuroda Naoki 
Published: July 2007

AbstractA technique for minimizing the normalized noise variance at the output of two‐dimensional (2‐D) recursive digital filters is developed where error spectrum shaping of the filter is performed by means of higher‐order feed‐back. First, the optimal solution of error feedback coefficients is derived. Then suboptimal error feedback coefficients are found in which the error feedback coefficients are symmetric. Here, both the optimal and suboptimal solutions are found analytically by solving the minimization problem of a quadratic form. Finally, a numerical example is given to check the validity of the proposed algorithm and it is shown that the proposed technique is effective even if the optimal or suboptimal coefficients are rounded to a power of 2.
A new normalized stochastic approximation algorithm using a time‐shift parameter
Authors: Okamura Atsushi , Kirimoto Tetsuo , Kondo Michimasa 
Published: July 2007

AbstractThis paper proposes a stochastic approximation adaptive algorithm aiming at a fast convergence speed, where the step size is normalized by the instantaneous power ‖x(k)‖2 of the input signal and a constant timeshift β is included at the weight update, as α/(k + β)‖x(k)‖2. It is shown first that the proposed algorithm gives a convergence to the Wiener solution. Then the transient response of the mean error is analyzed. It is shown as a result that β ⩾ α/2 is the condition for the time‐shift parameter to guarantee the uniform convergence of the algorithm.It is shown also that the speed of convergence is improved greatly compared to the conventional algorithm when α is set large enough so that the product of α and the minimum eigenvalue of the autocorrelation matrix exceeds 100 and the time‐shift parameter is set as β ∼ α/ 2. the performance is evaluated by a computer simulation. the above result of analysis is verified, and it is shown that the proposed algorithm can realize the same convergence speed as that of the recursive least‐squares (RLS) algorithm.
Computational complexity of multicommodity flow problems with uniform assignment of flow
Authors: Ito Hiro 
Published: July 2007

AbstractThis paper treats multicommodity flow problems with a flow assignment constraint. General multicommodity flow problems require both the path set in which the commodities are assigned and the volume to which the commodities are assigned for each path. However, in this paper, we treat only problems wherein paths are required. the flow is assigned to the paths uniformly. This problem appears in state‐and‐time‐dependent routing (STR), which is a kind of dynamic routing scheme in telecommunication networks. We show that this problem is NP‐complete and remains NP‐complete if the lengths (number of edges) of paths are restricted to less than or equal to two but can be solved in polynomial time if the path lengths are restricted to be less than or equal to two and the number of commodities is fixed.
Accurate measurement of vocal tract shapes using magnetic resonance imaging
Authors: Yang Chang‐Sheng , Kasuya Hideki , Kano Sigeru , Sato Toshihiko 
Published: July 2007

AbstractIn this paper, a method is developed for an accurate measurement of the three‐dimensional shape of the vocal tract, using magnetic resonance imaging (MRI), aiming at the analysis of the features of the vocal tract shape in the utterance by children, males and females. to derive the precise data for the shape of the vocal tract, the data for the vocal tract of the oral cavity is derived from the coronal MR image from the lips to the atlas. the data for the vocal tract from the glottis to the palate are derived from two kinds of horizontal MR images. High‐speed photography is used, and the imaging time is 2.9 s for each slice. the central line of the vocal tract is estimated from the mid‐sagittal MR image, and the vocal tract length is calculated. Based on the mid‐sagittal MR image, the three‐dimensional shape of the vocal tract is reconstructed from the vocal tract contour in the three kinds of images.To process the large amount of data, a method is developed that automatically extracts the vocal tract contour from the MR image. A correction method is proposed for the teeth shape which cannot be imaged by MRI, based on the MR image of the dental impression. the error of the measuring method is evaluated quantitatively using a model for the vocal tract. the transfer function for Japanese /a/ are estimated by the proposed measuring method, and the result is compared to the result of LPC analysis of the speech recorded at the site. It is seen as a result that the errors for F1, F2, and F3 are 8, 17, and 141 Hz, respectively.
Two decodable code pairs for the two‐user binary adder channel
Authors: Shi Jian‐Jun , Watanabe Yoichiro 
Published: July 2007

AbstractThis paper discusses the construction method for the two‐decodable code pair (C, S) for the two‐user binary additive channel as a model for the multipleaccess channel. (C, S) is constructed by defining the second code S as the independent set of the two‐order associated graph of the first code C. By restricting the code C to a particular linear code, it is possible to give an evaluation of the lower bound for the independence number of the two‐order associated graph. In several construction examples for the code pairs, the derived lower bound coincides with the independence number.
A design technique for linear‐phase finite impulse response digital filters with constant passband amplitude
Authors: Tsuchiya Mamoru 
Published: July 2007

AbstractThis paper describes a new design algorithm for finite impulse response (FIR) digital filters, which approximates constant passband amplitude and linear phase characteristics. The algorithm converts a filter's specification characteristic into a continuous impulse response by using the frequency response of a window function. The continuous impulse response is translated into discrete values to calculate tap‐gain coefficients of an FIR filter. In this design algorithm, window functions belonging to the Hanning window series (such as the Harris' window whose characteristics are already known) are used. This design algorithm is an analytical design technique, featuring a filter length that can be decided when the specification is decided and does not require iterative numerical calculations to calculate tap‐gain coefficients.
Obtaining an ideal associative memory by means of a simple hysteresis network
Authors: Jin'No Kenya , Saito Toshimichi 
Published: July 2007

AbstractThe hysteresis net is considered in which all crossconnections are uniform and the control paameters are restricted to two. an analysis is presented concentrating on the case where the state specified by the system is a stable equilibrium. A complete result is obtained for the type and number of the stable equilibria of the systm, as well as the convergence region for each stable equilibrium.As an application example of the hysteresis net, an associative memory is proposed which has the ideal memory‐recall function for the information. the associative memory is composed of three units which are the hysteresis net. the initial value generator, and the output circuit. It has the function that almost completely solves the problems in the traditional associative memory. In other words, all the contents which are prespecified as desirable are securely memorized and the false stable memory content is not produced. When incomplete information is given, the desired memory with the smallest Hamming distance is securely recalled. the proposed associative memory can very easily be implemented, and the desired content can always be stored using the switches.
A procedure for satiosfiability problems based on the partial instantiation technique
Authors: Yamamoto Masahito , Ohuchi Azuma , Ohyanagi Toshio 
Published: July 2007

AbstractWhen no function symbols occur in a first‐order predicate formula, there exists a procedure to decide the satisfiability of the formula. Examples of such procedures are the method based on Robinson's resolution principle and the method based on the partial instantiation technique by Jeroslow.This paper considers the case where the formula is in clausal form and no function symbols occur in it and proposes a satisfiability decision procedure based on the partial instantiation technique applicable to the considered case. the procedure is based on the partial instantiation technique, as in Jeroslow's method, but aims at the following aspects by utilizing the formula being in clausal form: (1) Davis‐Putnam's method is used in solving the satisfiability problem in the propositional logic; (2) the rapid expansion of the formula can be suppressed by expanding the formula with the clause as the unit; and (3) the number of unifications is reduced. the proposed method is compared to Jeroslow's method and the method based on the resolution principle, and then the effectiveness is demonstrated.
Reduction of specific absorption rate (SAR) in the human body by perfect conducting shield
Authors: Nakamura Takasi , Tokumaru Shinobu 
Published: July 2007

AbstractAs application of electromaganetic waves have inceased, effect on the human body has became a concern .Especially,these effects are significant problems for researchers who,because of their occupation , receive high does of electromagnetic illumination.In this paper, for researchers dealing with high‐power electromagnetic waves, a method is proposed for reducing the absorption power by means of a perfectly conducting shielding. As a fundamental stage, the reduction effect of the specific absorption rate (SAR) when a plane wave is incident on a cylindrical human model with a perfectly conducting shield is calculated and discussed. the effectiveness of the shield is presented.
Secret sharing schemes based on combinatorial designs
Authors: Song Youjin , Kurosawa Kaoru , Satoh Takashi , Tsujii Shigeo 
Published: July 2007

AbstractIn secret‐sharing schemes, a secret s is encoded as v1, …, vn, and vi is distributed to member Pi. By the access sets, we mean exactly those subsets of {Pi} which can recover the secret s. Previous secret‐sharing schemes have utilized the methods of polynomial interpolation [20] and projective geometry [6], among others. In this paper we show how to obtain secret‐sharing schemes from combinatorial designs, including orthogonal arrays (OAs) and t ‐ (v, k, 1) designs.
Improvement of convergence speed for subband adaptive digital filter using the multirate repeating method
Authors: Kiya Hitoshi , Nishikawa Kiyoshi , Ashihara Koji 
Published: July 2007

AbstractThe subband adaptive system, where the idea of the filter bank is applied to the adaptive filter, has a feature that a higher‐order adaptation can be reduced to lower‐order adaptations. the reduction of the order of the adaptive filter is related closely to the number of channels and the decimation ratio. the order of adaptive digital filter (ADF) is decreased greatly when the number of subbands is increased, and the decimation ratio is increased up to the maximum value. Then, however, the number of coefficient‐updates per unit time is decreased, which results in the deterioration of the convergence speed.From such a viewpoint, this paper discusses a method to improve the convergence speed, which is deteriorated in the subband adaptive system, due to the decimation. the idea of the proposed method is to utilize effectively the data which have been discarded in the decimation process and to improve the convergence speed. It is called the multirate repeating method.As the first step, the multirate repeating method is applied to the conventional subband adaptive system and the convergence speed is improved. Then a subband adaptive system is introduced in which the multirate repeating method can be utilized more effectively. As a result, a faster convergence is realized while retaining the ADF order‐reduction effect, which is an advantage of the subband adaptive system.
Mathematical considerations and improvement on the fuzzy vector quantization‐based hidden markov model
Authors: Tsuboka Eiichi , Nakahashi Jun'Ichi 
Published: July 2007

AbstractTwo new types of fuzzy vector quantizationbased/hidden Markov models (FVQ/HMM)—multiplication‐type and addition‐type—are formulated to remove a mathematical inconsistency in conventional FVQ/HMMs proposed by Tseng et al. Experiments show the MTFVQ/HMM gives the best recognition rate among VQ‐type HMMs. Lettingytbe an observation vector at timet, C1, …,CMbe clusters to whichytis classified andsibe thei‐the state of HMM, we show that MT‐FVQ/HMM is derivable by defining the occurrence degree ofytatsito be the negative of the Kullback‐Leibler divergence ofa posterioriprobability distribution {P(C1|yt), …P(CM|yt)} froma prioriprobability distribution {P(C1|si), …,P(CM|Si)}.
An analysis of pulse propagation dynamics in asynchronous chaotic neural networks
Authors: Ichinose Natsuhiro , Aiharai Kazuyuki 
Published: July 2007

AbstractIn this paper, we analyze some possible functions of networks where delays of pulse propagation and asynchronous events of pulse occurrence are considered, on the basis of a model of asynchronous chaotic neural networks. First, the model is proposed and response characteristics of the single neuron are numerically analyzed. Second, it is shown that the network model with loop structure can select time interval sequence peculiar to the network structure even if random noise is superimposed.
Theoretical analysis of nonlinear interaction of intense electromagnetic wave and plasma waves in the ionosphere
Authors: Matsumoto Hiroshi , Hirata Hisashi , Hashino Yoshitaka , Shinohara Naoki 
Published: July 2007

AbstractIt is well known that refraction, Faraday rotation, scintillation and absorption of microwaves take place when a microwave passes through an ionospheric plasma. However, when the amplitude of the microwave is large, nonlinear interactions occur with plasma in addition to these plasma interactions with a small signal microwave. Various phenomena not conceivable for weak microwaves used in communication can take place. Especially, it is predicted that the three‐wave resonance, which is the most fundamental nonlinear wave‐wave interaction, can be applied to the nonlinear wave‐wave interaction between the plasma and a large signal microwave.In this paper, the generating condition of the electrostatic plasma wave phenomena excitated in the plasma medium by a large signal electromagnetic wave is theoretically investigated and the nonlinear coupling coefficient between the large signal electromagnetic wave and the electrostatic plasma wave is derived.
Chaotic oscillations in dissipative and second‐order direct‐form II Digital Filters with a 2′s Complement Adder
Authors: Kawamata Masayuki , Sasaki Shinji , Higuchi Tatsuo 
Published: July 2007

AbstractThis paper studies the chaotic oscillations in a dissipative system generated by a second‐order directform II digital filter with a 2′s complement adder. the locus of this chaotic oscillation is absorbed into the parallel lines comprising the Cantor‐like set on the state space. In this paper, with respect to the chaotic oscillation, the initial value dependence of the locus, the output distribution, the power spectrum, the correlation function, and the fractal dimensions of the locus on the state space are investigated as the fundamental nature of the chaos. Also, by considering this filter as the two‐dimensional mapping, the mechanism generating the Cantorlike attractor is studied. From this study, it is shown that the 2′s complement adder characteristic has functions for stretching and folding of the state space causing the chaos. Also, the coefficient dependence of the Cantorlike attractor is studied and the relationship between the fractal dimensions of the locus and the coefficient are presented.
A note on lattice quantized coded modulation method
Authors: Minami Noriaki , Wakasugi Koichiro , Kasahara Masao 
Published: July 2007

AbstractThere is the expectation that lattice quantizers that use lattice basis vectors will be capable of source coding at high rates and low distortion. the application of lattice theory in coded‐modulation, on the other hand, is now at a practical stage (as can be seen in such applications as general telephone networks and mobile communication modems). Research into source coding schemes that use this type of lattice quantization has up to date been considered independently from research into lattice coded‐modulation. In this paper, a unified coding approach is considered. A new method is proposed that realizes in an integrated fashion coded‐modulation schemes that have recently received a great deal of attention as well as source coding methods suitable for data with frequency distributions typical of those of images. Then, as a specific example, a combined coding method is considered in detail that is realized by using the structure of the lattice to bridge lattice quantization and QAM modulation steps. As a result, it is shown that (i) it is possible to reduce the average modulation power of the entire system by performing a simple mapping that depends on the frequency of use of the lattice points; (ii) that maximum likelihood decoding can be more easily implemented since combined coding is accomplished in a way that preserves the structure of the lattices; and (iii) a simple, nearly optimum technique is proposed and it is shown that this system's average modulation power can also be reduced. Furthermore, simulation experiments are performed that clearly demonstrate the effectiveness of a system that combines E8 and A16 lattices with 256‐QAM modulation.
An equivalent transformation of multiterminal nets to two‐terminal net‐sets in the topological via minimization problem
Authors: Fujiyoshi Kunihiro , Kajitani Yoji 
Published: July 2007

AbstractIn via‐minimization in toplogical routing on ak‐layer, an equivalent transformation of at‐terminal net to a collection of two‐terminal nets is considered. an equivalent transformation to a special structure of twoterminal nets, which is called a two‐terminal net‐body, is presented for the case when available vias are throughhole vias andt⩽kand for the case when available vias are adjacent‐layer vias andt= 3. the key issue is the proof that the routings of thet‐terminal nets in optimum routing are classified into a few fixed number of cases with respect to the division of the layers and that each net is equivalently replaced with a two‐terminal netbody.
Optimal design method of separable‐denominator two‐dimensional digital filters based on a genetic algorithm
Authors: Kawamata Masayuki , Imakubo Jun , Higuchi Tatsuo 
Published: July 2007

AbstractThis paper proposes the optimal design for the separable‐denominator two‐dimensional digital filter, using the genetic algorithm (GA). the design proposed is for the specification in the frequency domain. the simple GA, which is the most basic among GA, is used in the proposed optimal design. the parameters of the transfer function of the separable‐denominator twodimensional digital filter are encoded into bit sequences, and then GA is applied to design the filter. By the use of the separable‐denominator transfer function, the stability of the filter is completely guaranteed.The approximation error of the proposed method is compared to that of the conventional method through design examples. the convergence of GA is discussed. It is shown that the proposed optimal design can easily cope with the modification of the design specification of the two‐dimensional digital filter. It is shown also that the filter can be designed using the maximum error or the absolute error sum as the error evaluation function in addition to the mean‐square error.
Fast coding algorithm for iterated transformation theory‐based coding by multiresolution tree search
Authors: Kawamata Masayuki , Nagahisa Masaki , Higuchi Tatsuo 
Published: July 2007

AbstractThe digital image coding technique, iterated transformation theory‐based coding (ITTBC), requires an enormous amount of encoding search time compared to other coding techniques because of the requisite roundrobin iterative code search procedure. the computational complexity of previously proposed ITTBC methods is on the order of O(N2), where N is the number of blocks contained in the image. an ITTBC method that uses a multiresolution tree search to reduce code search time is proposed here. In the proposed method, a search tree is constructed by subsampling and this search tree is used for code searches. the images stationed at the nodes of this search tree are formed from blocks extracted from the original image where, depending on their height in the tree, different subsampling rates are used. Thus, the constructed tree has different resolutions at different heights. By using this type of multiresolution tree search for code searches in the proposed coding method, the computational complexity of code searches becomes O(N log N), which is greatly reduced compared to previously proposed ITTBC methods. From experiments with the proposed coding method, it is shown that only a 0.5‐dB p‐pSNR performance loss is experienced while the encoding time of the proposed method is reduced to 14 percent of that required by previously proposed ITTBC systems.
A unifying treatment of general gradient adaptive digital filter and convergence analysis with arbitrary inputs
Authors: Chao Jinhui , Kawabe Shinobu , Tsujii Shigeo 
Published: July 2007

AbstractThe unifying treatment of a general gradient adaptive algorithm studied here is based on the principles of minimum mean square method and instrumental variable method by formulating the general oblique projection algorithm, including finite impulse response (FIR) and serial‐parallel infinite impulse response (IIR)‐type configurations. the oblique projection algorithm of low‐order past‐value data space is derived in which the dimension of past‐value data space can be easily adjusted, including the least mean square (LMS) method, learning‐identification method and gradient instrumental variable method (GIVE). Next, the new analysis model which describes the convergence process of general gradient algorithm is shown and the convergence conditions are indicated for the first and second moments with arbitrary inputs. It is found that this condition is more severe as compared with the white input. Moreover, the process of convergence of these conditions is studied by simulation.