Yukio Hiranaka

Gas-dependent response in the temperature transient of SnO2 gas sensors☆

Abstract This paper describes the gas-dependent response observed in the transient conductance patterns caused by surface temperature changes in various types of SnO2 gas sensors. These sensors have been investigated for the purpose of gas identification. The underlying objective of this research is how to extract gas-specific information to the fullest extent from a single gas sensor. In this case a temperature transient method is used. A step-like change in its heater voltage causes a conductance change in the sensor, resulting in a gas-dependent transient response. We examine the transient responses after dividing them by the conductance response when measured in clean air, and distinctive peaks are observed. The peak times depend on the particular gas species. Therefore this method will be useful for identifying gas species. The characteristics of several types of gas sensor have also been studied. We observe that the same types of sensor show similar gas dependency characteristics. Other types of sensor show different peak delay times. However, they all have gas-dependent features in common.

Envelope representations of pinna impulse responses relating to three‐dimensional localization of sound sources

Acoustical impulse responses of the external ear system are measured in order to investigate human three-dimensional auditory localization. A sound source of electric spark discharge is presented in nine directions for each of four vertical planes, 1.5 m from the center of the subjects head. The results show that a human pinna works as a compound sound reflector which produces major reflected components within 350 microseconds. The relationship between the direction of the sound source and the impulse response is clearly shown by the use of an envelope formation technique and radial ray displays.

Multi-dimensional intelligent sensing system using sensor array

Abstract In this paper two different kinds of multi-dimensional intelligent sensing systems are described. Both systems use a two-dimensional sensor array for sensing invisible objects. The intelligence of these systems gives us a visual moving image and the global structure of multi-dimensional dynamic phenomena by organizing local information from point-type multi-sensors based on a model of the phenomena. Overlapping with a video picture of the scene gives us the reality of the invisible state. These sensing systems may be useful for the understanding of a multi-dimensional dynamic state.

First experiment by two-dimensional digital mammography with synchrotron radiation

Two-dimensional digital mammography with synchrotron radiation was developed to obtain high-contrast images. The system consisted of a single-crystal monochromator with an asymmetrically reflecting silicon 〈311〉 crystal, an avalanche multiplication-type pick-up tube camera with a fluorescent plate and lens-coupling system, and a workstation. The preliminary experiment was carried out with a synchrotron light source at the Photon Factory, KEK, in Tsukuba. Breast phantom and human breast specimen were imaged using 20 keV monochromatic synchrotron X-rays. These images were compared with images obtained by a conventional mammography system. The minimal detectable diameter of microcalcification on the breast phantom was 165 µm by the two-dimensional synchrotron radiation imaging system and 196 µm by the conventional mammography system. In the breast specimens, microcalcification and soft-tissue masses were clearly imaged and their contrasts improved by about 18% and 38%, respectively, in the two-dimensional synchrotron radiation system. The entrance surface dose of the two-dimensional synchrotron radiation system was about 400 mR, which was almost the same value as the 420 mR delivered by the conventional mammography system. Two-dimensional synchrotron radiation digital mammography is considered to be a powerful imaging modality for diagnosing breast tumors.

Real‐time visualization of acoustic wave fronts by using a two‐dimensional microphone array

This article describes a real‐time visualization system for sound fields. The system includes a two‐dimensional microphone array (8×8), which eliminates the need for mechanically scanning the microphone and enables real‐time processing. Three methods are tested for drawing interpolated images of sound fields from the sparse sampling points. A frequency‐detection circuit is introduced to show the direction of sound propagation stroboscopically. Superposition of visualized sound wave fronts on the video picture of the field helps one to understand the sound fields present.

Multimedia and routing specific applications on IPv6 networks

The most promising applications of IPv6 networks might be to embed any network structure, logically, inside its vast addressing space. We show here some useful examples of such applications as a basic multimedia application of H.323 video conferencing, a method of phone number mapping, personal ID number mapping, machine ID number mapping all in the IPv6 address space, a method of multi-homing with IPv6 addressing, and that of IPv4 source address inclusion in IPv6 addresses. Some of the applications are implemented and evaluated.

Integrated image presentation of transmission and fluorescent X-ray CT using synchrotron radiation

Abstract We have developed a computed tomography (CT) system with synchrotron radiation (SR) to detect fluorescent X-rays and transmitted X-rays simultaneously. Both SR transmission X-ray CT (SR-TXCT) and SR fluorescent X-ray CT (SR-FXCT) can describe cross-sectional images with high spatial and contrast resolutions as compared to conventional CT. TXCT gives morphological information and FXCT gives functional information of organs. So, superposed display system for SR-FXCT and SR-TXCT images has been developed for clinical diagnosis with higher reliability. Preliminary experiment with brain phantom was carried out and the superposition of both images was performed. The superposed SR–CT image gave us both functional and morphological information easily with high reliability, thus demonstrating the usefulness of this system.

Numerical backward simulation model with case branching capability

The authors are studying backward simulators which trace from results to causes for comprehensive verification of system safety. It is not easy to make a backward simulation model because the forward model may not be expressed in a reversible formula, or it is not reversible in cases of multiple inputs or inclusion of internal state variables. In this paper, we propose a backward simulator which can incorporate numerical simulation models and has a case branching capability to deal with multiple inputs. As a practical simulation target, we implemented a simulator for testing stability of dynamic pricing for power usage control as a smart grid application. We show some illustrating results of the backward simulation.

Object-oriented framework for cross-layer communication

The layered structure of network processing is an effective formalism for constructing software systems. However, it has weakness in the efficiency of the total network system. Recently, cross-layer communications among network objects are expected to be a savior, which patches the lack of functionality in the layered structure. This paper describes the necessary conditions which must be met for implementing the cross-layer communication, a proposed object-oriented framework for it, an abstract oriented representation of data, and its evaluation relating to the data efficiency. Also, some application examples are shown.

Autonomic Buffer Control of Web Proxy Server

In this paper, we discuss the relation between the communication buffer size and the transfer speed under several web access patterns based on TCP/IP network, and present a scheme of autonomic control for the communication buffer. By this scheme, we could effectively improve the performance of web proxy server or web server, even when any number of accesses happen in a period of short time or large web files are transferred simultaneously. In the scheme, we design a buffer controller to decide the size of buffer for each connection based on socket, and a buffer information table to manager all the transfer buffers on a web server or proxy server.