Showing papers in "Electronics and Communications in Japan Part Iii-fundamental Electronic Science in 2003"

A sliding mode controller for manipulator driven by artificial muscle actuator

Abstract: An artificial muscle actuator manipulator is a manipulator driven by an artificial muscle actuator. The artificial muscle actuator has less weight and more output than pneumatic or hydraulic cylinders. It also has good flexibility and a high level of safety. Therefore, wide ranges of applications in industry and medical assistance are expected. If the nonlinear dynamics of the actuator are neglected, it is considered difficult to achieve accurate and fast trajectory tracking. For trajectory control of the manipulator, a new control approach with excellent robustness involving a sliding mode control technique is proposed, in which the instability of the characteristics of artificial muscle and the unknown portions of the manipulator are taken into account. Further, by an analysis based on Lyapunov stability theory, the stability and tracking error convergence of this control method are analyzed. The stability of the tracking error closed loop system consisting of the proposed controller is proved. Also, in the case with external disturbance, the proposed control method is modified to provide a sliding mode control method for the case with external disturbance. Finally, the effectiveness of the method is demonstrated by the results of simulation experiments. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(11): 57–64, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10046

Do we really have to consider covariance matrices for image feature points

Abstract: We first describe in a unified way how to compute the covariance matrix from the gray levels of the image. We then experimentally investigate whether or not the computed covariance matrix actually reflects the accuracy of the feature position by doing subpixel correction using variable template matching. We also test if the accuracy of the homography and the fundamental matrix can really be improved by optimization using the covariance matrix computed from the gray levels. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(1): 1–10, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10042

A Noise Reduction Method Based on Linear Prediction Analysis

Abstract: The linear prediction method works in such a way that the difference (prediction residual) between the objective signal and the output generated by making the objective signal a linear combination of the input signals is uncorrelated. Hence, in this linear prediction method, the linear predictor generates zero for the signal without correlation and recombines the voice for that with correlation. If this characteristic is used, recombined voice with suppressed noise can be obtained as the output of the linear predictor for voice with superposed white noise without correlation. Noise suppression can be realized by using this characteristic of the linear predictor. In this paper, a noise suppression method based on this linear prediction is discussed. According to this method, a noise suppression method without process delay can be realized. Also, no a priori information on the power spectrum of the noise is needed in this method. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(3): 1–10, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10056

An arbitrary scale image enlargement method with the prediction of high‐frequency components

Abstract: Enlargement of digital images is equivalent to narrowing the sampling spacing. Hence, it is necessary for enlargement of the digital images to estimate the high-frequency components lost in the sampling by some means. Recently, an enlargement method accompanied by estimation of lost high-frequency components has been proposed. The present authors have also noted the Laplacian pyramid layer expression, which is a multiresolution representation of digital images, and have proposed an enlargement method to estimate lost high-frequency components. Based on the Laplacian pyramid layered representation, estimation of unknown high-frequency components is equivalent to estimation of unknown high-resolution Laplacian components. Since the layered expression of the Laplacian pyramid has band division encoding as the objective, the image size between the layers is 2 and the enlargement method based on this expression is also limited to 2. However, it is possible to obtain a layered expression with an arbitrary size ratio by varying the passband width of the Gaussian filter and eliminating the pixels corresponding to the bandwidth, in place of continuous use of the half-band Gaussian filter and downsampling of the usual Laplacian pyramid layered image. In this paper, based on this concept, an enlargement method with high-frequency component estimation that allows setting of an arbitrary enlargement rate is proposed. The effectiveness of the proposed method is clarified from abundant application examples. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(8): 41–51, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10018

A quick AND/OR search for multimedia signals based on histogram features

Abstract: The problem of finding the point in time at which a known audio or video source (reference signal) appears in a long audio or video source (input signal) is referred to as a time series search, in contrast to a text string search. In a time series search, a search can be performed quickly by combining the audio and video, and then identifying several search conditions using logical equations. Thus, in this paper the authors describe the application of the time series active search method, a method to search audio signals proposed in the authors' previous paper, to video searches. Next, the authors propose an efficient algorithm for AND searches and OR searches of reference signals. In addition, the authors propose a multimodal AND search which combines audio and video. The proposed algorithms are faster than combining the results of searches performed individually. For instance, in an OR search of a reference signal, when the mutual similarity in the reference signals is above 0.8, five reference signals can be searched in a search time that is 1.2 times faster than searching one reference signal. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(12): 54–64, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10142

Designing linear phase FIR digital filters with flat passband and equiripple stopband characteristics

Abstract: It is known that linear phase FIR digital filters fall into four types considering the symmetry of impulse response. For example, filters of type 2 can be used at the time of partitioning and reconstruction of signals in multirate signal processing, and other types have similar special applications. Moreover, the linear phase FIR digital filters with flat passband and equiripple stopband characteristics are very important filters in practice because they have better time domain characteristics and less ringing than Chebyshev filters with equiripple stopband and passband characteristics. However, conventional design methods are restricted to type 1. In this paper, we therefore propose a method of design of linear phase FIR digital filters with flat passband and equiripple stopband characteristics for all four types. The proposed function is composed of two functions, one with a flat characteristic in the passband and the second with equiripple characteristics in the stopband. The latter function is obtained by using the well-known Remez algorithm only for the stopband. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(4): 89–95, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.1148

Estimation of chaotic ordinary differential equations by coevolutional genetic programming

Abstract: This paper describes a method of estimation of ordinary differential dynamics by Genetic Programming (GP) and discusses the accuracy of estimation. The dynamics is expressed by a tree structure and we obtain a numerical solution by carrying out digital integration (Runge-Kutta-Gill method) of the function system. The square error of the numerical solution and the original data is calculated and the inverse of the error is used as an evaluation of the individuals (functions) of the GP. Genetic operations such as crossover and mutation are carried out on pairs of solution candidates with high evaluation values, and the solutions (functions) are optimized. In addition, a coevolutional model that can efficiently perform simultaneous estimation of multiple functions is proposed. In the study of the estimation error, two systems, the Lorenz and Rossler systems, which are representatives of the chaotic ordinary differential model, are estimated and it is shown that a function of the same shape as the original one can be estimated in one-function estimation, and that in multiple-function (three-function) estimation, the coevolutional model is effective. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(2): 1–12, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10057

Robustness investigation of DCT digital watermark for printing and scanning

Abstract: This paper reports the effect of printing and scanning on digital watermarks for a hard copy image and investigates the necessary conditions for the watermark to be robust against the printing and scanning process. The effect of the printing and scanning process on the image content is presented first, and that on the Discrete Cosine Transform (DCT) domain is discussed next. Thus, we have necessary conditions for the watermark to be robust and present a sufficient condition to construct robust watermarking. It is realized by decreasing mutual interference between the embedded elements. This will enable us to make image content common to both the electrical nets and the physical nets. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(4): 11–19, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10059

Color Management of Liquid Crystal Display Placed under Light Environment

Abstract: We studied the color management of liquid crystal displays (LCDs) placed in a light environment. In this paper, we first explained LCD problems related to color management and proposed an appropriate color management system when using an LCD. We also applied this system and examined the color management of an LCD placed in a light environment. Based on the proposed method, we showed that favorable color reproduction properties are obtained for LCDs in a light environment as well as a dark room. We reevaluated the LCD from the perspective of compatibility with the ICC profile. LCDs have superior γ and brightness characteristics, but have the problem of the chromaticity coordinates of reference white and the primary colors changing in response to the input signal value. This indicated a problem related to the contrast ratio of the LCD and showed that the changes in the chromaticity coordinates of the primary colors can be adequately described if the leakage light is considered. Based on this, we proposed a suitable device profile and color management system for LCDs and demonstrated excellent color reproduction in a dark room. Next, we examined the LCD placed in a light environment. We showed that if the LCD is designed so that the surface reflected light produced in a light environment is handled in the same manner as leakage light and suitable surface reflected light is produced, fluctuations in the chromaticity coordinates of reference white could be avoided. We placed a prototype of this type of LCD in an actual light environment and applied and evaluated the proposed color management system. This result showed that a low color reproduction error could be maintained even when a dark image was displayed on an LCD placed in a light environment and confirmed a subjective improvement in the image quality. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(7): 1–14, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10074

Construction of high-dimensional neural networks by linear connections of matrices

Abstract: High-dimensional neural networks, such as complex neural networks and three-dimensional neural networks, have been proposed. They are capable of learning high-dimensional motions, which cannot be done by real-valued neural networks. In this paper, high-dimensional neurons are defined as vectors, and certain high-dimensional neural networks, such as complex neural networks, quaternary neural networks, and three-dimensional exterior neural networks, are unified in terms of a vector representation. It is shown that all of these types have the common feature of alternating matrices. The inverse quaternion neural network has the ability to learn rotations. In addition, it is shown that the proposed model cannot represent all rotations in neural networks that are higher than three-dimensional, and that the inverse quaternary neural network has a partial ability to learn rotations. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(11): 38–45, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10072

Cooperation and competition of agents in the auction of computer bridge

Abstract: The auction in contract bridge is a game with incomplete information. This paper models the process as an interaction among agents with a hypothetical reasoning mechanism. The criterion for the action of each agent is defined as “maximizing gain by cooperating with the partner and minimizing loss by competing with the opponents.” An agent with the following characteristics is created. Based on the course of bidding, the hands of both sides are estimated by hypothetical reasoning. Then flexible bids are made in an effort to obtain the contract with the greatest gain or smallest loss of points. Experiments show that in a game with incomplete information, it is useful not only to send information to the partner, but also to disrupt information exchange by the opponents. The effect of ambiguity of information on the behavior of both sides is discussed. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(12): 76–86, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10144

Applying the genetic programming to modeling of diffusion processes by using the CNN and its applications to the synchronization

Abstract: The CNN (Cellular Neural Network) has been proposed as a method of describing the system behavior of neuron coupling with a network structure. This is convenient for analysis of decision risk diffusion in economic society. However, in general, analysis of diffusion becomes possible only after inference of the system dynamics from the observed data. In this paper, using the GP (Genetic Programming) technique, a method is proposed for estimation of dynamics in the CNN. Based on this proposal, the signal diffusion is discussed and a method is proposed for controlling propagation. In order to approximate the system equation in CNN by GP, functions such as piecewise linear ones are prepared in addition to elementary operations. With these and the tree structure containing variables, the individual in the GP is defined. In the GP, two individuals with large degrees of fitness are selected. Crossover processing in the GP is carried out at an appropriately determined place so that an individual with higher capability for approximating the function is generated. In this method, it is shown that approximation is possible, including the system equation of the CNN exhibiting chaotic characteristics. Next, a method of estimating the propagation condition of the signal in CNN by using the estimated system equation is adopted. The results are compared with those derived by simulation and the validity of the computational equation is discussed. In this way, the diffusion coefficient for truncating the signal propagation on the network can be estimated. Further, using the fact that the system equation is available, a control method for synchronization for convergence of the cell state to a stationary point or a limit cycle is proposed. In this method, by means of the measured dynamical results, an appropriate control input in the feedback control can be estimated, allowing control to a balanced level to be attained within a shorter time. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(8): 19–30, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10064

Watermarking schemes using the addition property among DCT coefficients

Abstract: In general, a signal embedded in the low-frequency components of an image is less likely to be affected by attack. However, there is a problem of substantial degradation of image quality. In particular, if each divided block is processed, the blocking effects generated between adjacent blocks is more easily perceived. In this paper, an embedding method without blocking effects is proposed, making effective use of the superposition of the low-frequency components in the two-dimensional DCT basis images. Due to the effect of superposition of the two-dimensional DCT bases, the watermark information is not detected directly from the block with embedding, but extraction is performed from the subblocks in the block. In the proposed method, in order to provide robustness against geometrical transformation, the synchronization is recovered prior to extracting the watermark information. The robustness can be further enhanced by means of error correcting code. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(5): 11–23, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10048

A software reliability assessment method based on neural networks for distributed development environment

Abstract: The software development environment has been changing into a new development paradigm in CSSs (client/server systems) by the use of network computing technologies. Therefore, it is important to assess the reliability of software system in a distributed development environment because of increasing demands on quality and productivity in social systems. However, it is difficult to assess software reliability in recent years because the complexity of software systems has been increasing as a result of distributed system development. In this paper, we propose a software reliability assessment method considering the interaction among software components in the system-testing phase of a distributed development environment. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(11): 13–20, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10092

Improvement of perceptual watermarking based on the multiresolution analysis of still images

Abstract: Electronic watermarking has drawn attention as a way to prevent or limit unauthorized copying of digital contents and has been studied and improved extensively. In this paper, as an improved version of the electronic watermarking method proposed by Cox, a method is proposed in which a pseudorandom number sequence is embedded as watermarking information into the wavelet coefficients of the image. In this method, two conventional schemes known as improvements of Cox's method are included. With regard to this electronic watermarking scheme, the detection accuracy of the watermarking information and the quality of the image with watermarking are analyzed. It is shown that the detection accuracy of the watermarking information is better than in the conventional scheme. This conclusion is verified by numerical experiments. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(8): 31–40, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10036

Direction-of-Arrival Estimation of Speech Using Virtually Generated Multichannel Data from Two-Channel Microphone Array

Abstract: Recently, with rapid progress in multimedia technologies, hopes for a speech-based man-machine interface have increased. For high-quality voice collection and acquisition of the position information of the speaker, direction-of-arrival (DOA) estimation technology for voice with a microphone array has been discussed. However, one problem is large-scale implementation of the arrays. In the present research, a new DOA estimation method for a two-channel microphone array based on the harmonic structure of vowels is proposed. The present method has been applied in a real-world environment and its effectiveness has been confirmed. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(2): 33–42, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10038

The FDTD(2, 4) method for highly accurate acoustic analysis in three‐dimensional space

Abstract: Recently, simulation has become important in the field of acoustics. As an acoustic simulation method, the FDTD (Finite-Difference Time-Domain) method has been proposed. However, when this method is applied to a large-scale propagation analysis such as indoor acoustic propagation, the phase error cannot be neglected and causes a problem in the analysis. Therefore, a highly accurate method of analysis that can reduce the phase error is strongly desired. In the present paper, a three-dimensional FDTD(2, 4) method with second- and fourth-order accuracy in time and space is formulated as a highly accurate method of analysis. Also, the numerical dispersion and stability condition, which are important for understanding the characteristics of the method, are derived. It is demonstrated that the present method provides much greater accuracy than the FDTD method. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(11): 30–37, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10076

On the evaluation of performance of digital watermarking in the frequency domain

Abstract: With recent advances in digital technologies, it is now possible to access digital content and create copies easily. As a result, unauthorized copies are taken and the protection of copyright has become a problem. One of the solutions is electronic watermarking, for which various approaches have been proposed. However, since a method of evaluating the robustness of electronic watermarking methods has not been established, it is difficult to discuss superiority among the methods. In this paper, a method for evaluation of electronic watermarking methods using the frequency domain based on the operator representation of the image processing is proposed. By means of the proposed method, electronic watermarking schemes using discrete wavelet transform and discrete cosine transform are evaluated and the effectiveness of the proposed method is confirmed. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(4): 38–47, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10013

Method for solving nonlinear goal programming tasks with interval coefficients using GA

Abstract: In this study, the authors proposed a solution for directly using genetic algorithms without linear conversion for solving nonlinear goal programming problems involving interval coefficients. The proposed technique involves directly computing left-side interval numbers in the goal constraint equation from the genetic algorithm solution and comparing their size with those of the right-side numbers, for obtaining new difference variables. These difference variables vary depending on the goal type; they are defined using weights which express interval order evaluation criteria. In addition, as an example of application field for this method, the authors studied a large-scale problem for optimal design of system reliability involving interval coefficients, in order to clarify localization of this method. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(4): 55–65, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.1145

Testing and evaluation of a patrol robot system for hospitals

Abstract: To compensate for shortages of nurses and to reduce the stress of nursing work, we have attempted to create a patrol robot system for hospitals. The system consists of an autonomous mobile robot that can judge the condition of patients while moving around sickrooms, and a patrol information terminal to allow observation of the patrol conditions from the nurse center. For motion control during autonomous running, we propose a navigation technique using self-estimation of the robot's position from a sequence of view images and color information. Running experiments have been performed as a preliminary practical implementation. In the proposed technique, the combined use of broad and narrow position estimation is possible and real-time performance is excellent. In addition, the system is robust to environmental changes. A patient condition checking algorithm has been designed and the effectiveness of personal identification and facial expression recognition by SOM have been confirmed. Field tests at hospital facilities have confirmed the effectiveness of the proposed system equipped with the capability for navigation by visual information and with the patient condition checking algorithm. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(12): 14–26, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10139

A linear space representation of language probability through SVD of N‐gram matrix

Abstract: The number of parameters necessary for the word N-gram model is equal to the n-th power of the size of the vocabulary. As a result, compression of the parameter space is vital, depending on the field in question. In this research, singular value decomposition (SVD) of an N-pair word co-occurrence matrix is performed. The word and phrase state are taken to be vectors in a K-dimensional space. The authors then attempt to compress the N-gram probability parameter space using an approximation of the original matrix but with a lower number of dimensions. The results clearly show that in vector space, the Trigram model can be represented using roughly 17.5% fewer parameters. In addition, clustering is performed based on the distance in the defined space, and whether or not words are positioned appropriately in the linear space is investigated. These results confirm through a comparison using the same number of parameters that the entropy value is lower compared to the class model obtained using a method based on the maximization of the amount of mutual information, and that the positioning is good. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(8): 61–70, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10106

A neural network model of memory system using hippocampus

Abstract: When an episodic memory is to be transferred from short-term memory to long-term memory, there must be a buffer mechanism that temporarily stores the content of the short-term memory as a mid-term memory. It is considered that the hippocampus plays that role. In composing an episodic memory, there must be not only the association of different events without a time factor (spatial pattern), but also the association of different events containing time factors (time sequence pattern). This paper proposes a hippocampus neural network model, based on anatomical and physiological knowledge. The model features the following points. (i) By applying a learning rule where the input history is considered in the hippocampus CA3, which is regarded to have the associative recall function, it is made possible for the model to learn the time sequence pattern. (ii) The orthogonal coding function is provided in the gyrus dentatus, and the decoding function is provided in the hippocampus CA1. It is expected that the memory capacity of the hippocampus will be enlarged by providing the orthogonal coding function. It is shown by a numerical simulation that the mid-term memory can learn spatial and time sequence patterns, and that associative recall of the memory contents can be realized. This result implies that the proposed hippocampus model can retain episodic memory as a mid-term memory. The obtained results agree with physiological data, and demonstrate the effectiveness of the proposed model. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(6): 86–97, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.1010

On universality of both Bayes codes and Ziv-Lempel codes for sources which emit data sequence by block unit

Abstract: Ziv-Lempel (ZL) codes and Bayes codes are typical universal codes. An improved algorithm of the ZL code is widely used in compression software. On the other hand, practical use of Bayes codes is difficult due to the large amount of computation needed. However, a realizable algorithm in terms of computation effort has been constructed for the FSMX model group 9. In this paper, an information source generating a sequence by word units is assumed as a model that can represent the probabilistic structure of actual data such as text data. The asymptotic compression performance of both codes is analyzed and evaluated for the information source class (information source for the block unit) with a constant (fixed) word length. As a result, it is found that Bayes code cannot directly be universal as a coding algorithm for symbol units. On the other hand, the ZL78 code can be directly universal. Also, a configuration method for the Bayes coding method is given for an information source with a block unit. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(1): 58–69, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10017

Associative memory by neural networks with delays and pruning

Abstract: In the correlation-type associative memory model it is known that the storage capacity per synapse increases when synapses are pruned. In that case, however, the storage capacity of the whole network is decreased. In order to solve this difficulty, the authors introduce the synapse with delay, and propose a scheme in which the coupling rate of the synapse is reduced while retaining the number of synapses. As an example of such an approach, this paper discusses a discrete-time synchronous model with delayed coupling and synaptic pruning. The dynamics of the model is investigated theoretically by statistical neurodynamics, and the storage capacity is analyzed quantitatively. An analysis is performed for two types of synaptic pruning, random and systematic. In either case, it is seen that the storage capacity increases when the number of delay stages is increased while reducing the synaptic coupling rate, provided that the total number of synapses is kept constant. The increasing tendency is more marked in systematic pruning than in random pruning. These results were verified by comparing the results to those of computer simulation. The significance of the theoretical findings and the excessive generation and pruning of the synapses in the brain are also discussed from the viewpoint of the theory of computation. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(6): 48–58, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10037

Segmentation of ultrasonic images by using locally adaptive filter and wavelet analysis: Detection of superficial peripheral vein by a high-frequency ultrasonic equipment

Abstract: Ultrasonic diagnostic equipment is widely used, but has many problems such as acquiring noisy images and poorly quantifying the results for diagnosis. Therefore, a great deal of research has addressed the image processing of medical ultrasound images because of the need for automation and quantification of the diagnosis. This research began with the problem of region segmentation that automatically identifies living tissue or focus mass and currently relates to the quantification of tissue region information with the objective of tissue property diagnosis and the automatic diagnosis of 3D images. To achieve this, an accurate contour extraction method must be established. In this research, to achieve accurate region segmentation without losing the contour information in the medical ultrasound diagnostic images, we propose a new method based on an adaptive smoothing filter for suppressing speckle patterns and the 2D Gabor wavelet transform. Then we tried to automatically detect a superficial peripheral vein from an image of the forearm obtained by high-frequency ultrasonic diagnostic equipment, which is a difficult problem for conventional image analysis techniques. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(1): 36–45, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10026

Numerical verification of nonexistence of solutions for separable nonlinear equations and its application to all solutions algorithm

Abstract: In this paper, the objective is to derive with guaranteed accuracy all solutions of a finite-dimensional nonlinear equation within a certain range. In order to derive all solutions, it is important to extract efficiently the regions in which no solution exists. A new method is proposed in which nonexistence of solutions in a given region is judged with guaranteed accuracy. By solving specific numerical examples, the effectiveness of the proposed method is verified. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(5): 45–53, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10023

Minimum constituents of chaos neural network composed of conventional neurons

Abstract: Many studies of the neural network with chaotic output have been presented. In most of these, however, a neuron model or a network model is specially prepared to realize the chaotic response, and few studies have been based on the conventional model. This paper considers a neural network based on the conventional neuron model, such as is used in the Hopfield and other neural networks, and discusses the oscillation phenomenon. It is shown theoretically and experimentally that the behavior of the network composed of two neurons is either convergence or periodic oscillation. Then the network composed of three neurons is examined experimentally, and it is shown that convergence, periodic oscillation, quasi-periodic oscillation, or chaos can occur. In other words, it is shown that the minimum configuration of a neural network based on the conventional neuron model that can generate chaos is a network composed of three neurons. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(7): 62–71, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.1152

Interactive fuzzy programming using partial information about preference for multiobjective two‐level linear fractional programming problems

Abstract: This paper proposes an interactive fuzzy programming method for seeking a satisfactory solution for multiobjective two-level linear fractional programming problems in which the decision makers in the upper and lower levels have several objectives, by first setting up the fuzzy goals for several objectives of each decision maker and seeking a satisfactory solution for the degree of satisfaction of two decision makers in a cooperative manner. In the proposed method, the decision maker at the upper level sets the minimal satisfactory levels for each fuzzy goal and the decision maker at the lower level determines the aspiration levels. The minimal satisfactory levels are treated as a constraint and the solution closest to the aspiration levels of the decision maker at the lower level is computed. The ratio of the aggregative degrees of satisfaction of the decision makers in the upper and lower levels with the obtained solution is evaluated by using partial information on the preference of the decision makers. If the ratio of the degrees of satisfaction satisfies the given condition and the decision maker at the upper level is satisfied with this solution, then the interaction is complete. Otherwise, a satisfactory solution is sought by updating the minimal satisfactory and aspiration levels. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(9): 54–62, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10047

Computational methods through genetic algorithms for obtaining Stackelberg solutions to two‐level integer programming problems

Abstract: In this paper, by using the genetic algorithms whose effectiveness in optimization problems has been demonstrated recently, a derivation is attempted for Stackelberg solutions to two-level integer programming problems. It is assumed that each integer variable has upper and lower bounds. As the individuals in the genetic algorithm, 0-1 bit sequences are used. Each individual is required to satisfy the constraints and the decision of the decision maker at the lower level must be a rational response to the decision maker at the upper level. If these two conditions are not satisfied, a penalty is imposed on the fitness. By computational experiment, the proposed method is compared with that of Moore and Bard based on the branch-and-bound approach and the effectiveness of the proposed method is demonstrated. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(6): 59–66, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10012