Major components of a complete text reading system

The document image processes used in a recently developed text reading system are described. The system consists of three major components: document analysis, document understanding, and character segmentation/recognition. The document analysis component extracts lines of text from a page for recognition. The document understanding component extracts logical relationships between the document constituents. The character segmentation/recognition component extracts characters from a text line and recognizes them. Experiments on more than a hundred documents have proved that the proposed approaches to document analysis and document understanding are robust even for multicolumned and multiarticle documents containing graphics and photographs, and that the proposed character segmentation/recognition method is robust enough to cope with omnifont characters which frequently touch each other     

The characterization of two Dictyostelium discoideum genes encoding ribosomal proteins with sequence similarity to rat L27a and L37a

Two Dictyostelium discoideum ribosomal protein genes, denoted DdL27a and DdL37a, were isolated and sequenced. The DdL27a gene contained an open reading frame of 148 amino acids coding for a putative 16,407 Da protein, which was similar to rat L27a (82.6% similarity) and to ribosomal proteins from other species. The gene contained a 311-bp intron downstream from the ATG initiation codon with an A+T content of 75%. The DdL37a gene encoded a 9,999 Da protein consisting of 91 amino acids, which had high sequence similarity to rat, human, and chicken ribosomal protein L37a, and was interrupted by two introns of 254 bp and 75 bp in length. The DdL37a protein contained a typical zinc finger motif (Cys-X2-Cys-X14-Cys-X2-Cys), which may be involved in the interaction of proteins with nucleic acids. Genomic DNA blot analysis indicated that the DdL27a and DdL37a genes are present in single copies in the Dictyostelium haploid genome. The DdL27a and DdL37a mRNA were expressed maximally in growing amoebae, and their levels decreased during multicellular development, coordinately with the observed decrease in ribosome accumulation during later development.     

Electric-field-induced refractive index variation in quantum-well structure

The refractive index variation in a quantum-well structure by an electric field is given theoretically. The calculated variation is ?1% for an applied field of 3.1×105 V/cm in a 300 ?-thick GaInAsP/InP single quantum well, which is about 39 times larger than the bulk value. A semiconductor quantum-well structure is found theoretically to be a new material with a larger electro-optic coefficient. Application to a new optical switching device is also suggested.     

A review of the size of the energy gap in superconducting oxides

An attempt has been made to summarize a large body of data dealing with measurements of the energy gap in superconducting oxides like La_2–x Sr _x CuO_4–y , YBa₂Cu₃O_7–y , and related compounds. A plot of available data of the energy gap 2 as a function of the superconducting transition temperatureT _c revealed a large dispersion of some data from 2/k _B T _c =3.53 for the weak coupling BCS prediction. Nevertheless, we could conclude that the size of the energy gap in these exotic materials is within the weak coupling BCS prediction, in view of some controversial issues that could be responsible for the dispersion, such as the gap anisotropy as well as identification of the energy gap.     

Design of hydrodynamic bearings for high-speed HDD

 In this paper we discuss the technical issues of hydrodynamic bearings (HDB) for hard disk drives (HDD). We also report results of numerical analysis and of experiments aimed at solving the characteristic problems of high-speed HDDs. Received: 5 July 2001/Accepted: 21 December 2001     

Purposive Behavior Acquisition for a Real Robot by Vision-Based Reinforcement Learning

This paper presents a method of vision-based reinforcement learning by which a robot learns to shoot a ball into a goal. We discuss several issues in applying the reinforcement learning method to a real robot with vision sensor by which the robot can obtain information about the changes in an environment. First, we construct a state space in terms of size, position, and orientation of a ball and a goal in an image, and an action space is designed in terms of the action commands to be sent to the left and right motors of a mobile robot. This causes a state-action deviation problem in constructing the state and action spaces that reflect the outputs from physical sensors and actuators, respectively. To deal with this issue, an action set is constructed in a way that one action consists of a series of the same action primitive which is successively executed until the current state changes. Next, to speed up the learning time, a mechanism of Learning from Easy Missions (or LEM) is implemented. LEM reduces the learning time from exponential to almost linear order in the size of the state space. The results of computer simulations and real robot experiments are given.     

Spectral Narrowing of a Varactor-Integrated Resonant-Tunneling-Diode Terahertz Oscillator by Phase-Locked Loop

Spectral narrowing of a resonant-tunneling-diode (RTD) terahertz oscillator, which is useful for various applications of terahertz frequency range, such as an accurate gas spectroscopy, a frequency reference in various communication systems, etc., was achieved with a phase-locked loop system. The oscillator is composed of an RTD, a slot antenna, and a varactor diode for electrical frequency tuning. The output of the RTD oscillating at 610 GHz was down-converted to 400 MHz by a heterodyne detection. The phase noise was transformed to amplitude noise by a balanced mixer and fed back into the varactor diode. The loop filter for a stable operation is discussed. The spectral linewidth of 18.6 MHz in free-running operation was reduced to less than 1 Hz by the feedback.     

Automatic analysis of moving images

Cine film and videotape are used to record a variety of natural processes in biology, medicine, meteorology, etc. This paper describes a system which detects and tracks moving objects from these records to obtain meaningful measures of their movements, such as linear and angular velocities. Features of the system are as follows. 1) In order to detect moving objects that are usually blurred, temporal differences of gray values (differences between consecutive frames) are used to separate moving objects from stationary objects, in addition to spatial differences of gray values. 2) The results of previous frames are used to guide feature extraction process of the next frame so that efficient processing of moving pictures which consists of a large number of frames is possible. 3) Uncertain parts in the current frame, such as occluded objects, are deduced using information of previous frames. 4) Misinterpreted or unknown parts in previous frames are reanalyzed using the results of later frames where those parts could be found.     

Phase transition and the packing structure of the side mesogenic groups of liquid crystalline side-chain copolymers

Summary Copolymers consisting of cholesteryl 11-methacryloyloxy-undecanoate (ChMO-10) and t-buthyl methacrylate (t-BMA) were studied by DSC method and by small angle X-ray scattering method (SAXS). Although homopolymer (pChMO-10) has two different packing structures which are a single-layer packing structure and a two-layer packing one, copolymers (co-pChMO-10-t-BMA) have only the single layer packing one in their mesophase. Furthermore, transition entropy at a clearing point of co-pChMO-10-t-BMA (80/20) is larger than that of pChMO-10. Adequate distance of the mesogenic groups in the direction of a short axis of the mesogenic groups, produced by introduction of non-mesogenic units, seems to stabilize the single-layer packing structure.     

Warpage analysis of layered structures connected by direct brazing

In this study, we perform experiments and analyses to examine the warpage of Al/AlN layered structures connected by direct brazing. Al/AlN layered structures are considered under the high temperature fluctuations that occur in the brazing and baking processes. Three Al thicknesses are considered, using A3003 (JIS code) Al to clarify the variations in warpage. For the inelastic analysis, two types of constitutive model are used for Al: a non-linear kinematic hardening model considering cyclic hardening, viscoplasticity, and creep, and a conventional isotropic hardening model. Then, it is shown that the warpage in both brazing and baking processes can be simulated well using the kinematic hardening model.