bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluation of coded speech quality degraded by cell loss in ATM networks
Authors: Nagabuchi Hiromi , Kitawaki Nobuhiko 
Published: July 2007

AbstractThe asynchronous transfer mode (ATM) is considered interesting as the signal transfer mode in multimedia communication which can realize flexible and efficient channel usage. In ATM, the quality of speech is degraded by cellular handling of the signal which has a property different from the quality degradation in the conventional STM. Due to the small number of studies reported so far, the characteristics of the quality degradation have not been well understood.This paper presents the design data for the speech quality in ATM network and considers the cell loss as the inherent factor degrading the quality in ATM. The complex effect of the cell loss and the coding distortion on the overall subjective quality and the articulation of the speech is measured and discussed. For several methods of speech coding and cell structures, the degradation of quality is examined when the cell loss rate increases.It is shown that the 32‐kbit/s embedded ADPCM with the cell structure, where the lower two bits are selected with priority to suffer the loss, has a high immunity to the cell loss. Through the quality evaluation of the coded speech containing a cell loss, two factors are shown to be important: the speaker and the speech power at the site of cell loss. As a result of this study, new knowledge is obtained concerning the speech quality degradation characteristics in ATM network, and the data and knowledge useful in the speech quality design of ATM network are obtained.
An efficient three‐layer channel routing algorithm without vertical violation
Authors: Rhee Byungho , Sugai Yasuo , Hirata Hironori 
Published: July 2007

AbstractThis paper proposes a three‐layer channel routing algorithm for a new HVH routing method using the graph‐theoretic technique aiming at the minimization of the routing area. In the proposed method, the total net list is given as the input.To realize the routing with the lower bound for the number of tracks, the following steps are executed. First, the net requiring the routing with priority is selected based on the channel graph. Then, using that net as the core, the net group that can be assigned to the present track is constructed using the graph‐theoretic technique. The proposed method has the advantage that no vertical violation is produced between different nets nor is the stacked contact produced essentially within the same net.As a result of computer experiment for several well‐known problems, solutions with the minimum number of tracks are obtained. It should especially be noted that the vertical violation is not produced even in Deutsch's difficult problem. The routing can be realized within the lower bound for the number of tracks without the short vertical wire (where a short vertical wiring is employed in the horizontal wiring layer).
Generation of learning task sequences reflecting a fuzzy teaching strategy
Authors: Akahori Kanji 
Published: July 2007

AbstractThis paper proposes learning task sequencing in instructional design. The intention of the instructional designer in constructing the sequence is called teaching strategy. Previously, the author has proposed a teaching strategy model by introducing the concept of correlation [1, 2]. In this method, the subjective extent of the teaching strategy is represented by a number between 0 and 1. Such a numerical representation is somewhat difficult to determine from the viewpoint of the instructional designer. Consequently, a method is introduced which gives a subjective and fuzzy representation.There can be more than one learning task sequence which reflects the teaching strategy represented by the subjective fuzziness, and a method is presented that derives all sequences. By this method, the learning task sequence can be determined under the subjective and fuzzy teaching strategy.
An efficient method for making a fault dictionary for short‐circuit fault diagnosis of linear networks
Authors: Sakaguchi Kazuhiro , Kaneko Mineo 
Published: July 2007

AbstractIn the fault diagnosis for the breakdown fault of the analog circuit such as short‐ or open‐circuit, the fault dictionary usually is employed which describes the input‐output characteristics for the accessible nodes for all assumed faults. In the construction of the fault dictionary, generally a large number of inverse matrix calculations is required, and the computational complexity becomes tremendous with the increase of the circuit scale. Thus, how to construct and maintain the fault dictionary efficiently is important.This paper especially considers the short‐circuit fault in the fault diagnosis of the analog circuit and proposes a method which efficiently constructs the fault dictionary. This method considers the difference of the input‐output characteristics in normal and fault operations, for which the efficient calculation is presented. The method can be characterized as the extension of Johnson's proposal based on Householder's technique.In the diagnosis by dictionary, the fault generally is diagnosed by comparing the items of the fault dictionary and the measured result. By the proposed method, the computational complexity in constructing an item of the dictionary can be reduced to the same order as that of the comparison procedure (except for the preliminary calculations in common to the whole item).
Influence of dimensions on the sensitivity characteristics of thickness extensional mode piezoelectric ultrasonic transducers
Authors: Kamata Hiroshi , Chubachi Noriyoshi 
Published: July 2007

AbstractIf the thickness‐to‐width ratio of the thickness extensional mode piezoelectric ultrasonic transducer is not too large, the mode coupling will produce a complicated resonance system, and this will complicate the sensitivity characteristics, which is a basic characteristic of the ultrasonic transducer. If the dimensional ratio is adapted in such a way that the lateral mode can be suppressed, so the single mode of the thickness extension can be simplified, then the sensitivity characteristics of the ultrasonic transducer can be simplified. On the basis of lumped parameter equivalent circuit of the three‐dimensional coupled piezoelectric transducer, the three‐dimensional coupling sensitivity vs. frequency characteristics are derived, and the relationship between dimensional ratio and receiving sensitivity is clearly provided. From the frequency condition of the maximum sensitivity, the antiresonance coupling factor of the parallel longitudinal mode and, thus, the dimensional ratio condition of the mode simplification are derived. Furthermore, the degree of coupling with receiving sensitivity of parallel longitudinal mode is used as a measure to define the sensitivity coupling factor; and, based on the sensitivity coupling factor, the condition to simplify the sensitivity characteristics of ultrasonic transducer is shown.
Design of FIR digital filters with specified tolerances—A neural network approach
Authors: Zhang Xi , Iwakura Hiroshi 
Published: July 2007

AbstractThis paper presents a design method for the equal‐ripple, linear‐phase FIR digital filter when the tolerance for the error of magnitude response in the passband or stopband is specified. To realize the design when various constraints are imposed on the transfer function or magnitude response, the design problem is formulated as the optimization problem.A solution method is shown to solve the problem using the constrained neural net. When the lower bound of the magnitude error in the stopband is set as zero in the proposed method, the filter with double zeros in the stopband can easily be designed. Examples of application are shown for the minimum‐phase FIR filter and the matched filter pair with zero intersymbol interference.
Chaotic phenomena in an autonomous circuit with a nonlinear negative inductor
Authors: Nishio Yoshifumi , Mori Shinsaku , Inaba Naohiko 
Published: July 2007

AbstractThis paper proposed a new type of constrained circuit containing a complete saturation‐type nonlinear negative inductor and analyzes bifurcation phenomena and chaos generated in this circuit. The objective circuit is a three‐dimensional autonomous one and it is governed by the circuit equation which is similar to the constrained equation of the ideal diode type proposed by the present authors. Because this circuit equation is described piece‐wise by a two‐dimensional equation, a Poincaré map can be derived rigorously as a one‐dimensional map. By means of this map, the process of the generation of logistic map chaos can be explained in detail. Moreover, the analyzing results are verified by circuit experiments.
The identification problem and image reconstruction of the exponential X‐ray transform
Authors: Imiya Atsushi 
Published: July 2007

AbstractThe emission‐type CT which utilizes the radiation from the radioisotope (RI) injected into the body can reconstruct the biochemical information inside the body as an image. At present, the multicross‐sectional method is employed in reconstructing the three‐dimensional distribution of RI, as in the case of X‐ray CT.In this method, a spatial nonuniform resolution is produced in the reconstructed RI image. It should be noted, on the other hand, that RI injected into the body emits radiations in all directions in the space. By utilizing all those radiations, a three‐dimensional image can be reconstructed without a nonuniformity in the resolution.This paper shows that the three‐dimensional distribution of RI can directly be reconstructed from the radiations emitted spatially from inside the body. It is shown first that the problem to determine the three‐dimensional distribution of RI from the radiations is the inverse problem with the exponential line integral as the measured value. The relation between the Fourier transform of the projections by the exponential line integral and the Fourier transform of the original three‐dimensional image is analyzed. Then it is shown that the radiation attenuation coefficient of RI can be determined only from the projection data.Furthermore, based on the relation between the Fourier and Hankel transformations, a method is derived for the direct three‐dimensional image reconstruction from the radiation projection using the series expansion.
A function generator based on quadratic B‐spline functions
Authors: Kamada Masaru , Toraichi Kazuo , Nakamura Norio 
Published: July 2007

AbstractAn improved smooth analog signal generator is proposed which purges digital‐to‐analog (DA) conversion phase distortions.The author's previous system for such a generator had the following problems: 1) circuit parameter errors that accumulated at the circuit output due to the complicated circuit structure and 2) the output could turn out to be discontinuous because it was a subtle patchwork of discontinuous functions, even though theoretically they were smoothly connected. These problems have been avoided through careful tuning of the circuit parameters.The present paper proposes an improved system, free of the above problems. This was accomplished through the following: 1) the analog circuit was simplified by retaining as many functions as possible in the digital circuit and 2) the analog output signal was made inherently smooth through a linear combination of time‐limited smooth (i.e., B‐spline) functions. Consequently, the present system produces more accurate linear phase characteristics with easier circuit parameter tuning. Its effectiveness was evaluated on a trial product whose performance was compared to that of the previous generator.
Realization of monolithic variable gyrators and their application to active filters
Authors: Ishibashi Yukio 
Published: July 2007

AbstractWith the development of IC and LSI technology, it is strongly desired that integration of the analog filter be realized. This paper proposes a method to construct the differential input voltage‐controlled current source (VCCS) and the differential input, differential output VCCS, using the conventional current multiplier type VCCS. The features of the proposed construction is that the VCCS characteristics can be varied by the control current and the transconductance is not affected by the absolute accuracy of the resistances as long as their relative accuracy is maintained.A method also is presented in which the conventional LC filter is simulated using the gyrators composed of the proposed circuits. Then, by adding a resistor‐controlled current source circuit, a circuit construction also is presented whose control current can be determined by an external resistor so that the characteristics of more than one VCCS can be controlled.To verify the effectiveness of the proposed method, the third‐order elliptic filter with a 0.25‐dB ripple is designed. As a result of computer simulation, it is verified that the characteristics change little by the ambient temperature of ‐10 to 60°C and that the cut‐off frequency changes little for ±12.5 percent variation of the supply voltage. Thus, it is shown that the analog filter can be integrated without using the tuning system which has often been employed.
A convolutional coded modulation scheme designed for controlling signaling probability
Authors: Saito Hidetoshi , Kohno Ryuji , Imai Hideki 
Published: July 2007

AbstractMost coded modulation schemes, such as Ungerboeck's trellis coded modulation (TCM), are based on equiprobabilities of the signal space points. These schemes improve the bit error rate (BER) performance if all signals have the same norm. For signals with different norm, unequiprobable schemes result in much more improved of BER performance and larger coding gain than those of equiprobable ones. Consequently, a new convolutional coded modulation system utilizing symbol unequiprobability is proposed. Calderbank and Ozarow proposed another system using unequiprobable signaling [2]. In their system a shaping code is employed to save the average signal power without decrease of the coding gain. In the system proposed herein, to save the average signal power and to obtain more coding gain, a convolutional encoder designed in the real or complex number field is introduced to control the signal probabilities directly.An optimum distribution of signaling probability is derived such that the minimum free Euclidean distance can be maximized. Then the convolutional encoder which can achieve the optimum distribution of signal points is derived theoretically. BER performance of the proposed system using such a convolutional encoder is evaluated by computer simulations.Finally, it is shown that for the 16‐QAM system, the proposed scheme achieves about 1.0‐dB improvement in coding gain over Ungerboeck's TCM.
Oscillations in negative resistance oscillatory circuit containing periodically operating analog switch
Authors: Matsuki Michitaka , Mori Shinsaku 
Published: July 2007

AbstractSome examples of the electronic circuit containing periodically operating switches are the switched‐capacitor circuit, which also are circuits switching the passive elements. This paper considers the nonlinear circuit containing a switch as an example of the circuit containing the periodically switched active element. The circuit containing a nonlinear negative resistor with N‐shaped voltage‐current characteristic and a resonant circuit is considered. In this type of circuit, even if an oscillation is not self‐excited, there arises an extraordinary phenomenon that an oscillation is produced for a certain range of the clock frequency when a switch is inserted between the nonlinear resistor and the resonant circuit and is operated periodically. This paper analyzes this phenomenon.It is verified experimentally that there arises a hard oscillation in the low‐ and high‐frequency range of the clock. A theoretical analysis is attempted for this phenomenon. It is seen that even if a self‐oscillation is not produced in the circuit containing a negative resistance, there can arise an oscillation by periodically operating a switch. This is interesting since it may lead to the effective use of the negative resistance.
An error position recording method for optical disks
Authors: Suematsu Toshinari , Imai Hideki 
Published: July 2007

AbstractIn order to improve the reliability of optical disks, the nature of the data errors generated on optical disks must be studied in detail. To accomplish this, recording the positions of all errors generated on the optical disk, then performing various analyses based on them is an effective method. Because the optical disk has a large capacity and the error rate of the data is relatively high, the amount of error position data is tremendous and the error position data must be efficiently recorded. On the other hand, when the excess data format for highly efficient data becomes complex, the processing speed of the analysis diminishes. In this paper, we explain an error position data recording method that was applied to recording the error positions of optical disks. This method can efficiently record the error positions in a relatively simple data format. Then a mathematical model of error generation is used to examine the efficiency of this method when random errors and burst errors are generated. Furthermore, an example is presented where this method is applied to error positions measured on an optical disk and its efficiency is evident.
On the generalizability and adaptability of a self‐organization clustering
Authors: Miyanaga Yoshikazu , Tochinai Koji , Okumura Shinji 
Published: July 2007

AbstractThis paper constructs an adaptive clustering method based on the Mahalanobis distance and discusses its essential characteristics with respect to the adaptability and generalizability. From some experimental results, this method is shown to provide a sufficient adaptive clustering ability. The clustering method proposed in this paper is based on a self‐organization method by which every useful independent base can be obtained on a characteristic space. Thus, the user's effort of learning becomes minimum compared with supervised learning. In addition, clustering based on an adaptive method is performed to consider the time variation of the characteristics. Furthermore, to improve the generalizability, a set of clusters is reconstructed in every certain period and a system is constructed such that accurate cluster sets and recognition are obtained. Because this reconstruction is also processed in a self‐organizing way, it does not require learning from an external source. To evaluate the characteristics quantitatively, its effectiveness is shown by several simulation experiments.
Performance evaluation of a minimum bit error decoding algorithm of convolutional codes and its application
Authors: Ohashi Masayoshi , Yasuda Yutaka 
Published: July 2007

AbstractBasic decoding characteristics of a minimum bit error decoding (MBED), originally proposed by Bahl et al., is investigated. It is shown that MBED can predict the bit error rate of each decoded bit with good precision. Then MBED is applied to the convolutional/Reed‐Solomon (RS) concatenated coding scheme. The outer RS codes are decoded by an erasure decoding using the symbol erasure information provided from the MBED results of inner convolutional codes. Simulation results show that the overall bit error rate is reduced one‐half to one‐third more than the conventional nonerasure decoding.
Nonlinear equivalent circuits of acoustic devices
Authors: Cho Yasuo , Wakita Junji 
Published: July 2007

AbstractMason's equivalent circuit is well known as a linear equivalent circuit for acoustic devices. By combining Mason's equivalent circuit with Smith's equivalent circuit of surface acoustic wave devices, it becomes a very effective tool for the physical interpretation of acoustic devices.If such equivalent circuit analysis can also be performed for the nonlinear problem, then comparatively simpler and accurate analysis can be obtained for almost all types of nonlinear problems.In this paper, equations are formulated to analyze the equivalent circuit of nonlinear‐type acoustic devices. At first, Mason's equivalent circuit is extended to the nonlinear region for the basic circuits of a thin bar of length‐extensional vibration and a broad plate of thickness‐extensional vibrations.Next, this equivalent circuit is used to analyze the thickness‐extensional vibration of Z‐cut LiNbO3 and second harmonic generation at the resonance point is clarified. Finally, these nonlinear equivalent circuits of length‐extensional vibration are applied to determine the nonlinear constants of PZT ceramics and the nonlinear constants of the equivalent circuit are clarified.
On the availability of trellis decoding schemes for continuous phase FSK signals employing limiter discriminator detection
Authors: Iwanami Yasunori 
Published: July 2007

AbstractAlthough a trellis‐coded modulation scheme has been applied to multilevel PSK or QAM signals, its application for the continuous‐phase FSK (CPFSK) with the limiter‐discriminator detection has not been investigated well and the coding gain associated with it has not been obvious yet. In this paper, using a linear approximation, we have designed modulation parameters of this scheme. We have also executed the exact computer simulation and made clear the problem to obtain the actual coding gain as well as to increase them. Furthermore, utilizing the intersymbol interference caused by the IF filter, which greatly deteriorates the bit error rate (BER) performance in this scheme, we have proposed a sequence estimation scheme using the Viterbi algorithm. In this scheme, the sending signals are those of the binary continuous phase FSK. Through computer simulations, we have made clear that large improvements of BER really exist. The sequence estimation scheme is considered to work better than the trellis encoded scheme when considering the BER performance and the complexity of transmitter and receiver.
Evaluation method of shielding performance of cubic magnetically shielded room—simulation of magnetic field analysis with finite element method
Authors: Ishikawa Noboru , Kasai Naoko , Kado Hisashi , Koyanagi Masao , Higuchi Masanori 
Published: July 2007

AbstractThe shielding factor of a large magnetically shielded room (MSR) cannot be measured by the usual methods. Successful results have been achieved by magnetic field analysis using the finite element method. Investigation of the shielding factor of an MSR included examination of: (1) a uniform magnetic field; (2) a magnetic field produced by an electric current flowing in a single circular coil (single‐coil field); and (3) a magnetic field produced by electric current flowing in a pair of Helmholtz coils (pair coil field).As a result, it was found that the shielding factor within MSRs varies with both the external magnetic field distribution condition and the position being measured within the MSR. The shielding factor at the center (when due to a uniform magnetic field) is lower than the shielding factor at the center when the field is produced by circular coils. The approximate equation expressing the ratio of the shielding factor due to the field of a circular current and that due to a uniform field using the center of the MSR as the measurement point was deduced as a function of the circular coil radius and its position. The method of evaluation of shielding performance of a cubic‐shaped MSR involves measuring the shielding factor due to the field produced by a circular coil and then transforming the results to yield the shielding factor for a uniform field. The approximate equation obtained thusly produces standardized shielding performance.