Hiroshi Dozono

The Analysis of Pen Inputs of Handwritten Symbols using Self Organizing Maps and its Application to User Authentication

To realize ubiquitous computing, mobile computers such as PDAs and smart phones will be important components. However, the mobile computers tend to be used without authentication because they should be usable as soon as the power becomes on. In this paper, we propose an authentication method without losing the usability of PDA. With this method, the user is authenticated using the pen pressure pattern measured by tracing the symbols which are displayed on the screen with stylus. From the analyses of pen pressure patterns using self organizing maps, the symbols which are suitable for authentication are selected. 70% of the users can be authenticated by this method from the authentication experiments using the symbols.

An integration method of multi-modal biometrics using supervised pareto learning self organizing maps

This paper proposes a method for the integration of multi-modal biometrics. As the conventional authentication method, password system is mostly used. But, password mechanism has many issues. In order to solve the problems, biometric authentication methods are often used. But, the authentication method using biological characteristics, such as fingerprint, also has some problems. In this paper, we propose a authentication method using multi-modal behavior biometrics sampled from keystroke timings and handwritten patterns. And supervised Pareto learning self organizing maps which integrate the multi-modal vectors is proposed. The performance of this method is confirmed by the authentication experiments.

Effects of Stress and Magnetostriction on Loss and Vibration Characteristics of Motor

A method of 3-D finite element magnetomechanical analysis is developed to investigate the effect of magnetostriction (MS) and stress on the core loss and vibration of motors. Shrink-fit stress calculation is carried out using static structural analysis and equivalent thermal force calculated by a novel method using the thermal stress tensor. A method of core loss calculation is proposed to take account of the 3-D stress in the core loss calculation. The methods are applied to the core loss and the vibration analysis of a permanent magnet motor. Numerical results show that the stator core loss increases significantly due to the shrink-fit stress. However, the radial velocity of the housing surface slightly decreases due to the MS and further decreases due to the shrink-fit stress because the MS increases under compressive stress.

Loss Reduction of Reactor With Grain-Oriented Silicon Steel Plates

To reduce the iron loss of a reactor stacked with non-oriented steel plates, we have proposed the method of loss reduction improving the iron core configuration using the magnetic field analysis taking account of the laminated structure by the homogenization technique. In this paper, the iron loss reduction method is expanded to a reactor stacked with grain-oriented steel plates. The magnetic field analysis taking account of the laminated structure and steel plate anisotropy using homogenization technique is developed. The flux concentration due to the laminated structure, steel plate anisotropy, and joint between the leg and yoke of the reactor is analyzed and relaxed by the improvement of the core and joint configurations. It is shown that the iron loss can be about 36% reduced by the improvements.

Evaluation of Stray Load Losses in Cores and Secondary Conductors of Induction Motor Using Magnetic Field Analysis

To develop further higher efficiency induction motors, the reduction of the stray load losses, which are the increase of loss in the load condition relative to that in no-load test condition, should be investigated by using the magnetic field analysis. However, the calculation of the stray load losses using the magnetic field analysis requires high computation cost due to consideration of the slot harmonics in the flux densities, and the large time constant. In this paper, to evaluate the stray load losses in the cores and the secondary conductors of induction motors using the two-dimensional (2-D) magnetic field analysis within practical computation cost, some useful techniques, to mention a few, the nonconforming technique and the simplified time-periodic explicit error correction method, are introduced. Then, the stray load loss of an actual induction motor without skew is evaluated by the developed 2-D magnetic field analysis. It is shown that the calculated no-load losses are almost the same with the measured one, and the stray load losses in the stator core and secondary conductors due to the harmonic components in the secondary current are large.

Homogenization Technique of Laminated Core Taking Account of Eddy Currents Under Rotational Flux Without Edge Effect

A homogenization technique of a laminated core taking account of the eddy currents in the steel plates by combining a three-dimensional (3-D) solid core model with a one-dimensional (1-D) steel plate model has already been proposed. In this paper, to apply the proposed technique to a motor core, in which flux rotates, the 1-D eddy current analysis of the steel plate is expanded to a 3-D analysis. The proposed method is applied to a simple laminated core model under the rotational flux in the linear analysis. Then, the eddy current loss obtained from the developed method is compared with those obtained by the homogeneous solid core model with 1-D steel plate model and the real laminated core model. It is shown that error occurs by neglecting the edge of the model but the accuracy is much improved in the eddy current loss calculated by using the proposed method.

Coupled Magneto-Mechanical Analysis Considering Permeability Variation by Stress Due to Both Magnetostriction and Electromagnetism

A general model for the coupled analysis of magneto-mechanical systems is developed by minimizing the continuum energy functional of the system using the calculus of variation. This approach, which is in contrast with the traditional approach of minimizing after discretization, allows the use of strain and stress tensors, vector identities and the divergence theorem, and results in coupled governing equations of the system with three coupling terms; the magnetic stress tensor, the magnetostriction stress tensor, and the magnetostriction reluctivity. The model uses the information contained in the set of experimental magnetostriction curves dependent on stress to calculate the permeability variation due to stress. The governing equations are then discretized using the Galerkin method resulting in methods for the calculation of nodal magnetic and magnetostriction forces including the coupling effects. Finally the model is applied to a simple 2D problem and the flux density distributions using the proposed method and the traditional method of using experimental magnetization curves are compared.

The spherical hidden markov self organizing map for learning time series data

In modern society, the more complex information and technology become, the more important data analysis become. In particular, a data, which has a variety of elements, is complex, and it is extremely difficult to estimate the state which generates data from observed data. To handle those hidden states, we propose an appropriate model using Spherical-Self Organizing Map (S-SOM) with Hidden Markov Model (HMM) which can estimate the hidden state.

Application of Supervised Pareto Learning Self Organizing Maps and Its Incremental Learning

We have proposed Supervised Pareto Learning Self Organizing Maps(SP-SOM) based on the concept of Pareto optimality for the integration of multiple vectors and applied SP-SOM to the biometric authentication system which uses multiple behavior characteristics as feature vectors. In this paper, we examine performance of SP-SOM for the generic classification problem using iris data set. Furthermore, we propose the incremental learning algorithm for SP-SOM and examine effectiveness in a classification problem and adaptation ability to the change of the behavior biometric features by time.

Coupled Magneto-Mechanical Analysis in Isotropic Materials Under Multiaxial Stress

In this paper, a model for the coupled analysis of magneto-mechanical problems with isotropic materials is proposed in which the effect of stress in transverse direction with respect to the flux density is also considered. To take into account the Villari effect in this case, magnetization data under zero stress and magnetostriction (MS) data under various levels of stress are required. The model uses stress-free magnetization curve and a set of MS curves together with the stress tensor to calculate the permeability variation due to the stress, including the stress-induced anisotropy. Unlike available methods in which an equivalent scalar stress is defined and used for the evaluation of permeability, the proposed method uses the full stress tensor. The model is then applied to a simple 2-D problem and the flux distribution in three cases of uncoupled, coupled without, and coupled with considering the transverse stress are compared.