Genetic network programming (GNP) is a graph-based evolutionary algorithm with fixed size, which has been proven to solve complicated problems efficiently and effectively. In this paper, variable size genetic network programming (GNPvs) with binomial distribution has been proposed, which will change the size of the individuals and obtain their optimal size during evolution. The proposed method will select the number of nodes to move from one parent GNP to another parent GNP during crossover to implement the new feature of GNP. The probability of selecting the number of nodes to move satisfies a binomial distribution. The proposed method can keep the effectiveness of crossover, improve the performance of GNP, and find the optimal size of the individuals. The well-known testbed Tileworld is used to show the numerical results in the simulations. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

This paper focuses on the voltages electromagnetically induced by the multiple return strokes involved in a triggered lightning on an overhead power line and a vertical signal line of an automatic weather station (AWS), and the backflow currents and residual voltages in a surge protection device (SPD) embedded in the power line. Pulses of voltage on the overhead power line corresponding to the return strokes with the peak currents ranging from −6.67 to −26.47 kA showed bipolar features. Subpeaks and main peaks ranged from 0.99 to 4.47 kV and from −4.98 to −10.31 kV, respectively. The voltage waveforms corresponding to the return strokes on the vertical signal line of wind speed were of two types: with and without a subpeak after the main peak. All the main peaks, with the peak value from −0.41 to −3.10 kV, were ‘V’ shaped. A significant relationship exists between the peak currents of the return strokes and the 10–90% average gradients of the voltages. The peaks of currents through the SPD ranged from −0.22 to −1.64 kA. The durations of residual voltages ranged from 0.6 to 5.9 ms, average value being 2.1 ms. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

To enhance the automatic text classification task, this paper proposes a novel approach for treating the problem of inductive bias incurred by the centroid classifier assumption. This approach is a trainable classifier, which takes into account tfidf as a text feature. The main goal of the proposed approach is to take advantage of the most similar training errors in the classification model for successively updating that model based on a certain threshold. The proposed approach is practical and flexible to implement. The complete performance of the proposed approach is measured at several threshold values on the Reuters-21578 text categorization collection. Experimental results show that the proposed approach can improve the performance of the centroid classifier better than traditional approaches (traditional centroid classifier, support vector machines, decision trees, Bayes nets, and N Bayes) by 1, 1.2, 4.1, 7.5, and 11%, respectively. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

The main reason for the invention of computer programming languages is for these languages to express a command-to-control machine behavior. Some of these programming languages have specific advantages that are used in specific environments such as structured query language (SQL), hypertext markup language (HTML), and spreadsheet. The common definitions of these languages are domain-specific languages (DSLs). Although DSLs are the best way to deal with specific systems, it is hard to use with other environments or platforms. Groovy is a dynamic programming language that runs on the Java virtual machine. Groovy has some features that allow programmers to manage DSLs within its unique style. Groovy has some disadvantages because it does not support all Java features and syntax while also producing unnecessary byte code during compilation. This paper proposes an extended-architecture technique to implement a computer programming language and compiler through extending Java with Groovy language. The extensible language is called ‘JGroovy’. And JGroovy is supported both by Java and Groovy language. We implement the compiler for JGroovy and call it the ‘JGroovy compiler’ (JGC). By its extended architecture, JGC is more compatible for Java source code than Javac can claim to be. And it also produces a better and more compact byte code than the Groovy compiler, with an approximate improvement of 8–12%. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Winding hot-spot temperature (HST) is an important factor that affects the insulation life of an oil-immersed power transformer. Thus, precise prediction and close monitoring of HSTs are necessary to avoid thermal damage. In this paper, a differential equation for HST prediction is presented, which takes into consideration the effects of the top-oil temperature variations and thermal dynamics of the load. A discrete form of this equation based on the framework of the Kalman filter (KF) algorithm was used to establish a real-time estimation model for the HST. The KF-based model was validated by a sample heat-run test involving a transformer setup in the laboratory. Moreover, the proposed model was applied to a real, large power transformer and compared with the classical IEEE-Annex G method. Results show that the HSTs estimated by the KF-based model are closer to the measured values. The exhibited potential applicability and generality in real-time prediction for HST demonstrate that the proposed model can be employed for online monitoring of HSTs for large power transformers. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

The iterated unscented Kalman filter (IUKF) is a promising nonlinear tracking algorithm. However, we find that the IUKF has poor performance in tracking accuracy and will diverge easily when the variance of observation noise is large, because the iterated state prediction is nonorthogonal to the current observation after the first iteration. This will increase the proportion of current observation in state estimate and lead to the tendency for the final iteration result to be closer to the observation compared with the optimal solution, which is a phenomenon termed the nonorthogonal problem here. We solve this problem by augmenting the state vector with the process and observation noise vectors and slightly reconstructing the IUKF formula. Simulation results show that the proposed algorithm has better tracking performance than IUKF. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Classical estimation of distribution algorithms (EDAs) generally use truncation selection to estimate the distribution of the good individuals while ignoring the bad ones. However, various researches in evolutionary algorithms (EAs) have reported that the bad individuals may affect and help solving the problem. This paper proposes a new method to use the bad individuals by studying the substructures rather than the entire individual structures to solve reinforcement learning (RL) problems, which generally factorize their entire solutions to the sequences of state–action pairs. This work was studied in a recent graph-based EDA named probabilistic model building genetic network programming (PMBGNP), which could solve RL problems successfully, to propose an extended PMBGNP. The effectiveness of this work is verified in an RL problem, namely robot control. Compared to other related work, results show that the proposed method can significantly speed up the evolution efficiency. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

In medical image processing, the segmentation of overlapping nuclei is one of the challenging topics, which relates to its application in diagnostic pathology. To achieve the quantification accuracy (ACC) of the diagnosis, we propose an overlapping nuclei segmentation algorithm using the principle of direction-based flow tracking (DBFT). The DBFT, which consists of direction field preparation and direction field tracking, is performed to provide the direction field and the labeled distinct single nucleus. Its performance is validated with 6375 nuclei from 29 images and compared with two popular overlapping objects segmentation methods, i.e., traditional watershed (TWS) and marker-controlled watershed (MCWS). While the sensitivity (SS) of the DBFT, TWS, and MCWS is 0.981, 0.990, and 0.966, respectively, and the corresponding positive predictive value (PPV) is 0.948, 0.831, and 0.910. The ACC values and F₁ measures obtained from the combination of SS and PPV are used as the total performance measures. While the ACC values from DBFT, TWS, and MCWS are 0.930, 0.824, and 0.882, respectively, the corresponding F₁ measures are 0.964, 0.904, and 0.937. The results clearly show that the DBFT is the best among three methods because it provides the maximum numbers on both ACC and F₁ values. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

This paper presents the state estimation of power system in which not only the bus voltages but also the states of the flexible AC transmission system (FACTS) are considered as the state variables. By using the rectangular form of state variables and equivalent measurement techniques, a linear measurement model with constraints of FACTS device is obtained. The predictor–corrector interior point method based on the weighted least absolute value criterion is developed for solving the optimization problem. Simulation results on the modified IEEE 14-bus and 118-bus test systems are provided. The numerical results indicate the effectiveness of the proposed approach. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

In this paper, first, turn-to-turn fault in a synchronous machine stator winding is investigated, and its inductances are derived with the winding function method. Then, using the nonlinear control theory, the first-order Poincaré map of the synchronous machine is computed, and a new extended Poincaré map of the machine is established. Also, the characteristic multipliers of the synchronous machine are calculated by the Poincaré map. This new map is capable of analyzing electrical machines in the nonlinear and unbalanced cases for evaluation of stability, bifurcation, and chaos phenomena. The results show that the new map is an effective technique for modeling and analyzing any AC electrical machines. The characteristic multipliers and the Lyapunov exponents of the extended map indicate the system's condition. Chaotic phenomena are observed in some machines with internal faults. Since chaotic systems have a continuous spectrum and various kinds of frequencies in their spectrum, identification of the internal fault location is not easy with harmonic analyses such as Fourier spectrum method on the excitation current in synchronous machines. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Integration of wind power generation into power systems has been limited because of the problem of frequency regulation during light-load periods at night in some areas in Japan. As a solution, autonomous frequency regulation by electric water heaters (EWHs) has been proposed. A control board to control the power consumption of an EWH is fabricated. It measures both the power system frequency and thermal energy stored in a hot-water tank, and then turns on/off a heating element according to a control algorithm. It is confirmed that the board can measure power system frequency every 1 s with a resolution of better than 0.01 Hz and that it can measure the vertical temperature distribution in the storage tank with an acceptable accuracy to calculate the future power consumption ratio, which is a parameter that decides the turn on/off of the heating element while considering end-user comfort. Then, an EWH with autonomous frequency regulation is fabricated by embedding the board, and the EWH is operated to investigate the performance. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

In a standard support vector machine (SVM), the training process has O(n³) time and O(n²) space complexities, where n is the size of the training dataset. For very large datasets, it is thus computationally infeasible. Reducing the size of training dataset is naturally considered as a method to solve this problem. SVM classifiers are constructed by using the training samples called support vectors (SVs) that lie close to the separation boundary. Thus, removing the other samples that are not relevant to SVs might have no effect on building the separation boundary. In other words, we need to reserve the samples that are likely to be SVs. Therefore, a method based on edge detection techniques is proposed to extract such samples near the separation boundary. In order to avoid overfitting, we also use a clustering algorithm to keep the distribution properties of the training dataset. The samples selected by the edge detector and the centroids of clusters are used to reconstruct the training dataset. In the proposed approach, the edge detection technique helps us to extract the local properties around the separation boundary and the clustering algorithm preserves the properties of the entire data. The reconstructed training dataset with a smaller number of samples can make the training process very fast without degrading the classification accuracy. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

In this paper, we suggest a new approach for accurate measurement of three-dimensional eye movements employing dual-camera acquisition. Two calibrated mini CCD cameras are used to capture two simultaneous images of one eye. Center-of-mass and template-matching algorithms are utilized to obtain two-dimensional coordinates of the center of pupil and iris striation. Instead of asking each subject to fulfill intricate calibration steps, a novel and simpler technique to solve geometric distortion is presented by utilizing direct linear transformation (DLT) algorithm which requires only one preliminary calibration procedure for each camera without changing any camera installation. The DLT algorithm is then used to extract three-dimensional coordinates of the center of the pupil and iris striation from prior two-dimensional coordinates, allowing the three-dimensional angular positions of the eye to be computed. Real-time eyeball visualization based on tracking results is incorporated to help clinicians diagnose eye movements. Experimental results show that our system has high accuracy, as the average errors in the horizontal, vertical, and torsional angular positions were confined to 0.15°, 0.14°, and 0.20°, respectively. Real-time implementation demonstrates that our system can be used in clinical routines to observe either voluntary or involuntary human eye movements. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

In this paper, we propose a method, named cutting detrended fluctuation analysis (cutting DFA), for the evaluation of global and local fractal properties from data containing noisy observational errors. This method evaluates how the Hurst exponent varies by cutting out in the order of the largest deviation from the mean value. An analysis of the simulated fractal signal reveals that cutting DFA exhibits a linear transition of the Hurst exponent with respect to the cutting rate. The mean value and the slope thereof reflect the global and local fractal properties of the time series, respectively. We then analyze the long-term heart rate variability of congestive heart failure (CHF) patients and healthy subjects with observational errors. It is demonstrated that CHF patients have a higher value in the mean Hurst exponent than healthy subjects, indicating a higher global Hurst exponent. Also, it is demonstrated that healthy subjects have a statistically significant difference in slope from monofractal time series, while CHF patients do not. These results indicate that the local fractal property of healthy subjects is far from monofractal time series, which matches previous findings. Therefore, it is confirmed that cutting DFA extracts fractal properties of original heart rate variability from data containing observational errors. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Traditional principal component analysis (PCA) based face recognition algorithms have a low recognition accuracy due to the influence of noise and illumination changes. This paper proposes a robust, intelligent PCA-based face recognition framework in the complicated illumination database when using multiple training images per person (MTIP-CID). There are mainly two improvements in the proposed method. One is that a face-recognition-oriented genetic-based clustering algorithm is introduced to reduce the influence of a large number of classes on the classification accuracy in the MTIP-CID. The other is that a classifier based on fuzzy class association rules (FCARs) is applied to mine the inherent relationships between eigenfaces and to improve the robustness of PCA-based face recognition in noisy environments. Experimental results on the extended Yale-B database demonstrate that the proposed framework performs better and is more robust against noise compared with other traditional face recognition algorithms, i.e. linear discriminant analysis (LDA) and local binary patterns (LBPs). © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Because of the unclear conclusion of the repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) effects on the posterior electroencephalogram (EEG) alpha wave, this study is aimed at investigating these unclear effects. Transcranial stimulation effects are observed by analyzing a measured EEG at the occipital area between prestimulation and the poststimulation. The EEG alpha power and alpha coherence are calculated and analyzed in terms of the ratio between eyes closed and eyes open periods. The results reveal that alpha power ratio at the individual alpha frequency (IAF) significantly increases after the 1-Hz rTMS and cathodal tDCS and slightly decreases after the anodal tDCS compared to the control and the sham conditions. The results also show that there is a significant difference between the inhibited and excited conditions. Similarities are observed in the patterns of the alpha coherence ratio and alpha power changes. The alpha coherence increases in the rTMS and cathodal tDCS conditions, and decreases in the anodal tDCS condition but these effects occur only when comparing across the hemispheres (O1–O2 and P3–P4). It can be summarized that the EEG alpha wave can be influenced by the transcranial stimulations. The rTMS and cathodal tDCS seem to facilitate the alpha activity and the anodal tDCS inhibits it. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

In this paper, we propose an efficient algorithm to recognize actions of human interaction. Unlike previous algorithms using two participants' actions, the proposed algorithm estimates the action contribution of participants to determine which participant's action is the major action for correct interaction recognition. To estimate this contribution, we construct a contribution interaction model for each interaction category in which both participants carry out major actions. Using the contribution models, we design a method that automatically estimates the contribution of participants and classifies interaction samples into “co-contribution” and “single-contribution” interactions. At the same time, the major actions in the “single-contribution” interactions are determined. We evaluate our method on the UT-interaction dataset and our original interaction dataset (LIMU). Recognition results indicate the robustness of the proposed method and the high estimation accuracy obtained: estimation accuracies of 96 and 98% in set 1 and set 2 of the UT dataset, respectively, and 97.8% in the LIMU dataset. Based on the estimation results, we extract the major action information for interaction recognition. Average recognition accuracies of 93.3% in set 1 and 91.7% in set 2 of the UT dataset were obtained. Our result is at least 5% better than those obtained with previous algorithms. For the LIMU dataset, recognition accuracy reached 91.1%. It was 8.9% higher than the recognition result without contribution estimation. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Transparency is an important indicator to evaluate the performance of a bilateral control system. Uncompensated disturbances in high frequency degrade the transparency in the traditional disturbance observer (DOB) based bilateral control. This paper analyzes the influence of the uncompensated disturbances, and proposes a sliding mode assist disturbance observer (SMADO) to solve the problem. The sliding mode technique helps the original DOB to estimate the disturbances in high frequency by making use of a rapid switching control value. The required switching gain is small in the proposal, which is good for alleviating the chattering. Moreover, to avoid conservative and arbitrary design of the switching gain, a reasonable benchmark is proposed by employing the estimation error between the original DOB and another parallel DOB with a different cutoff frequency. The validity of the proposal is confirmed by experiments. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

High-performance control of a switched reluctance (SR) motor strictly requires an accurate nonlinear motor model as well as an appropriate control strategy. Since recent modeling methods are either complex or not accurate enough, this paper focuses on overcoming such drawdacks. An experimental method is proposed to collect useful data for modeling a 6/4 SR motor at running condition. Nonlinear modeling is done by an algorithm, which also enables simple static torque computation. The algorithm presents not only the static torque data but also an estimator model for instantaneous torque estimation during real-time operation, which is very important for most torque control strategies. The nonlinear model is experimantally tested, and its accuracy verified. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Stand-alone power systems (SPS) are attracting more and more interest with the global move toward distributed generation (DG). Without strong support from the power grid, they suffer from poor load-following capability at varying loads. A cache power that has fast response and high energy efficiency is demanded. As a solution, this paper provides an AC power technology based on flywheel energy storage. Different from the other DC generation technologies such as electric double layer capacitor (EDLC) or superconducting magnetic energy storage (SMES), the proposed flywheel system generates AC power and therefore can be directly connected to the power line without any power semiconductors. Furthermore, the proposed technology realizes power in/out automatically in response to the frequency/voltage variation of the power line. Therefore, this system has the advantages of robustness, simplicity, and fast response. Besides, by getting rid of power semiconductors, the proposed flywheel system has a good overload capability as high as two to three times. We prove by simulation and experimentation the validity and effectiveness of the proposed technology to provide cache power for stand-alone power systems. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

A novel regression model with a sine and cosine wave (SCW) equation is proposed based on the latest and accurately recorded global radiation data during the year 1994–2009 in this letter. The SCW model and two trigonometric functions (sine wave and cosine wave) are employed to estimate global solar radiation by using the day of the year for six meteorological stations in Xinjiang Autonomous Regions of China. Estimated values were compared with measured values in terms of statistical indicators. This letter finds that the SCW model performed better than the other models for Xinjiang Province. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Multidirectional Associative Memory (MAM) is an associative memory model that can deal with multiple associations. It can be considered as a generalized Bidirectional Associative Memory (BAM). Multidirectional Associative Memory with a Hidden Layer (MAMH) improves the storage capacity of MAM. However, the improvement is limited. In this paper, we propose Multidirectional Associative Memory with Two Hidden Layers (MAMTH). It can provide, theoretically unlimited, much larger storage capacity. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Evaluation of the mental workload during training for ship handling has usually depended on professionals (captain, pilot) who have lots of experience on board. We are attempting to evaluate a ship navigator's mental workload based on a physiological index. The physiological indices, namely heart rate variability (R–R interval), nasal temperature, and salivary amylase, are good indices for reading the mental workload during ship handling. Moreover, we find the possibility of using salivary NO as a good index for evaluating the ship navigator's mental workload. Salivary NO is expected to have a specific characteristic to represent quick response on the spot and the trend. We confirmed the response of students during simulator training, and then carried out the experiment on professionals on a real ship. We propose that salivary NO can show a ship navigator's stress for ship handling in the simulator and on a real ship. This work to evaluate the ship navigator's mental workload using salivary NO is the first attempt worldwide. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

This letter proposes a tennis instruction support system to provide stroke-form information obtained through measurement and analysis of ground reaction forces. The originality of the proposed method can be summarized as follows: (i) simultaneous outdoor measurements of ground reaction forces on the front part (toes) and back part (heels) of both feet are conducted for visual recognition of the center of gravity of a tennis player's body during a stroke, and (ii) the comparison between experienced players and beginners is examined so that the system can be used for training beginners. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

We propose an improved 3 × 3 sequential Euclidean distance transform (DT) using quad-scan propagation. Our method has a separable scan structure that can be processed with a multicore processor to reduce computation time with a better accuracy. The computer simulation shows that the proposed DT algorithm approximates the Euclidean map more precisely than conventional 3 × 3 DTs while reducing dramatically computation time comparable to 8-point sequential Euclidean distance algorithm. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Anatomical reentry has been identified as a major cause of clinical cardiac arrhythmia. The probability for anatomical reentry is strongly dependent on the structures and cell characteristics of the causal cardiac regions. In this paper, we propose a simple in vitro model system for analyzing and simulating the anatomical reentry phenomenon in cardiac tissues. Rat ventricular myocytes were cultured and aligned in predesigned structures by using a microcontact printing method. Excitation propagation in the cultures was visualized and evaluated by applying electrical stimulation and the calcium imaging technique. We confirmed that differences between passage times along the two excitation pathways were modulated by changing the structures of cultured myocytes. This simple in vitro model system will be useful for studying the anatomical reentry phenomenon. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

We have optimized the sputtering conditions for sputtered IrOx and TiN electrodes for retinal prosthesis. The basic electrochemical characteristics were evaluated by cyclic voltammetry, and the surface morphology was inspected by atomic force microscopy. To measure the charge delivery capacity (CDC), a 300-µm diameter electrode was formed, a balanced biphasic current pulse was applied, and the voltage response was measured. From the experimental results, the CDCs of IrOx and TiN in the best sputtering conditions were improved by more than 8 and 4 times compared to that of Pt, respectively. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.