Thermal Stresses Around Two Collinear Interface Cracks between a Nonhomogeneous Bonding Layer and One of the Two Dissimilar Elastic Half-Planes Under Uniform Heat Flux

In composite materials, in which two dissimilar elastic half-planes are bonded by a nonhomogeneous elastic layer, two collinear cracks are situated at the interface between the nonhomogeneous elastic layer and one of the two dissimilar half-planes. The stress intensity factors are solved under uniform heat flux normal to the cracks. The material properties of the bonding layer vary continuously from the lower half-plane to the upper half-plane. The boundary conditions are reduced to dual integral equations using the Fourier transform technique. In order to satisfy the boundary conditions outside the cracks, the differences in temperature and displacements at the crack surfaces are expanded in a series of functions that vanish outside the cracks. The unknown coefficients in each series are evaluated using the Schmidt method. The stress intensity factors were calculated numerically for selected crack configurations.     

High-pressure Study of a Doped-type Organic Superconductor, κ-(BEDT-TTF)4Hg2.89Br8

Physical properties of the organic charge-transfer complex that may be regarded as a doping system are presented. We measured resistivity of an ambient-pressure superconductor, κ-(BEDT-TTF)₄Hg_2.89Br₈, as functions of temperature, magnetic field, and pressure. Metallic and superconducting states of this salt are possibly attributable to the doping effect, which originates from incommensurability of Hg chain because band structure calculation predicts strong electron-electron correlation enough to localize the itinerant electrons. We uncovered anomalous pressure and magnetic field dependences of superconductivity as well as non-Fermi liquid behavior in the normal-state resistivity at low pressures. In addition, we observed a pressure-induced crossover to the Fermi liquid behavior, which is seen in non-doped κ-type salts at any pressures.     

Statistics of Nadaraya-Watson estimator errors in surrogate-based optimization

For the optimization under uncertainty problem, there has been recent interest in coupling trust-region methods with surrogate surfaces or function approximations. There are many theoretical and statistical issues that must be carefully considered in following such an approach. Herein, the Nadaraya-Watson estimator is used for the smooth function approximation, and the effects of observation noise and random sampling on estimator error are examined. For the fundamental optimization problem where the exact function is quadratic, analytical results are derived for the mean-square error of the difference and gradient of the function. It is also shown how these statistics are related to the trust-region method, how the analytical results can be used to determine the bandwidth of the kernel of the estimator, and how third-order terms can affect the error statistics.     

Information filtering using SVD and ICA

We propose an information filtering system for documents by a user profile using latent semantics obtained by singular value decomposition (SVD) and independent component analysis (ICA). In information filtering systems, it is useful to analyze the latent semantics of documents. ICA is one method to analyze the latent semantics. We assume that topics are independent of each other. Hence, when ICA is applied to documents, we obtain the topics included in the documents. By using SVD remove noises before applying ICA, we can improve the accuracy of topic extraction. By representation of the documents with those topics, we improve recommendations by the user profile. In addition, we construct a user profile with a genetic algorithm (GA) and evaluate it by 11-point average precision. We carried out an experiment using a test collection to confirm the advantages of the proposed method. This work was presented in part at the 10th International Symposium on Artificial Life and Robotics, Oita, Japan, February 4–6, 2005     

International real-time streaming of 4K digital cinema

This paper describes the world’s first real-time, international transmission of 4K digital cinema and 4K Super High Definition (SHD) digital video at iGrid 2005, hosted at the California Institute of Telecommunications and Information Technology (Calit2) at the University of California, San Diego. Nearly six hours of live and pre-recorded 4K motion picture and audio content was streamed to iGrid in San Diego from the Research Institute for Digital Media and Content (DMC) at Keio University in Tokyo.

To implement this demonstration, several new technologies were introduced, including a prototype high-performance 4K compressed multicasting system called “JPEG 2000 Flexcast”, and “Soundscape”, a practical scheme for synchronizing audio and video transmitted from different locations over IP networks.

These iGrid 2005 demonstrations proved that it is now feasible to implement networked professional audio/video applications–production, post-production and distribution–even at 4K quality over IP networks up to 15,000 km long. The demonstrations also showed the new 4K motion picture technology being introduced for digital cinema can be usefully applied to other network applications such as remote telepresence, distance learning and scientific visualization.     

Driver Modeling Based on Driving Behavior and Its Evaluation in Driver Identification

All drivers have habits behind the wheel. Different drivers vary in how they hit the gas and brake pedals, how they turn the steering wheel, and how much following distance they keep to follow a vehicle safely and comfortably. In this paper, we model such driving behaviors as car-following and pedal operation patterns. The relationship between following distance and velocity mapped into a two-dimensional space is modeled for each driver with an optimal velocity model approximated by a nonlinear function or with a statistical method of a Gaussian mixture model (GMM). Pedal operation patterns are also modeled with GMMs that represent the distributions of raw pedal operation signals or spectral features extracted through spectral analysis of the raw pedal operation signals. The driver models are evaluated in driver identification experiments using driving signals collected in a driving simulator and in a real vehicle. Experimental results show that the driver model based on the spectral features of pedal operation signals efficiently models driver individual differences and achieves an identification rate of 76.8% for a field test with 276 drivers, resulting in a relative error reduction of 55% over driver models that use raw pedal operation signals without spectral analysis     

Three-dimensional problem of a running crack

The problem of an uniformly propagating finite crack in an infinite medium is solved using the dynamic equations of elasticity in 3-dimensions. Equal and opposite tractions are applied arbitrarily to the crack surfaces. The problem is reduced to the dual integral equations and solved with the aid of the series method. The numerical examples are presented on some graphs.     

Diffraction of a stress wave by a cylindrical cavity in an infinite elastic strip

The scattering of an incident plane shock wave by a cylindrical circular cavity in an infinite elastic strip is considered. In the Laplace transformed domain, boundary conditions at the plane surfaces and those at the circular hole are satisfied with the help of the Fourier transformation and the Schmidt method. A numerical Laplace inversion technique is taken to obtain the stresses in the physical space.