Masao Murota

Characteristics of leaky surface waves propagating on Li/sub 2/B/sub 4/O/sub 7/

The propagation characteristics of leaky surface waves on Li/sub 2/B/sub 4/O/sub 7/ substrate are theoretically calculated for all cuts and propagation directions by changing Eulers angle. The theoretical contour maps for phase velocity, electromechanical coupling constant (K/sup 2/), temperature coefficient of delay (TCD), propagation loss, and power-flow angle (PFA) are displayed. From these results, the following features of leaky surface waves are obtained. Phase velocity varies from 3570 to 5242 m/s. The maximum value of K/sup 2/ is about 6.4%, which is much larger than 1.6% for the Rayleigh wave. At 45 degrees , 90 degrees , and 70 degrees , the values of phase velocity, TCD, K/sup 2/, propagation loss, and PFA are about 3780 m/s, 0.15 p.p.m./ degrees C, 3.6%, 0.87 dB/ lambda , and 27.4 degrees , respectively. The effects of a thin aluminum plate on the TCD are also investigated.<<ETX>>

Comparison of the theoretical temperature dependence of power leakage with experiments on LST-cut quartz

The theoretical temperature dependence of the center frequency and insertion loss of SAW (surface acoustic wave) filters on the LST-cut of quartz is compared with experimental results. Theoretical values including metallization effect are in good agreement with experiments. The temperature dependence of the center frequency on the LST-cut filters is greatly affected by both the cut-angle and the aluminium thickness of the interdigital transducer. The temperature dependence of insertion loss is mainly affected by the cut-angle. It is found by theoretical calculation that there is a combination of cut-angle and an aluminium thickness which exhibits both the minimum temperature frequency shift and change of insertion loss.<<ETX>>

Characteristic of leaky surface waves propagating on Li2B4O7 substrate with a thin aluminum plate

Characteristics of leaky surface waves propagating on a Li2B4O7 substrate with a thin aluminum plate are theoretically calculated. Phase velocity, TCD, and propagation loss are shown changing the thickness of the aluminum plate on a (0°, θ, 75°)-cut for 65°≤θ≤8°. The (0°, 73°, 75°)-cut has zero TCD for both electrically open and aluminum short surfaces with H/λ=0.02 thickness. Temperature dependence of fractional time delay(Δτ/τ) and propagation loss is also shown.

Characteristics of Longitudinal Leaky Surface Wave Propagating on La3Ga5SiO14 Substrate

The propagation characteristics of the longitudinal leaky surface wave propagating on a La3Ga5SiO14 substrate were theoretically investigated for all cuts and propagation directions. The results of temperature coefficient of delay (TCD), electro-mechanical coupling constant (K2) and phase velocity were displayed on contour maps. Cuts with zero TCD were obtained at Eulers angles of (20°,θ,ψ) and (30°,θ,ψ). Temperature dependence of fractional time delay (Δτ/τ) on (90°,90°,0°)-cut changes only by 18.5 ppm from -30°C to 110°C. This cut has very good temperature characteristics.

Elastic Constants and Temperature Coefficients of LiTaO3 for SAW Application

A method to obtain material constants for SAW application is proposed and new elastic constants and temperature coefficients of LiTaO3 are displayed. They were numerically calculated from experimental SAW velocities using the method of least squares and n-th dimension Newtons iterative method. Theoretical values with the new constants are in very good agreement with experimental data on X, Y, and Z-cuts at all temperatures. These constants should be practical for theoretical prediction.

Quasi–Lamé–Mode Quartz–Crystal Resonators

In this paper, quasi-Lam?-mode quartz-crystal resonators formed by etching processes are examined theoretically and experimentally. First, the frequency equation for a Y-plate quartz-crystal resonator is derived by the energy method. Then, the relationship between the cut angles ?y and ?y to vibrate the quasi-Lam? mode is investigated. There are many combinations of ?y and ?y for which the first-order temperature coefficient ? becomes zero. Finally, it is theoretically and experimentally demonstrated that the temperature characteristics of a Y-plate quasi-Lam?-mode quartz-crystal resonator is superior to that of a pure-Lam?-mode resonator.

Characteristics of Leaky Surface Waves Propagating on LiTaO3 Substrate

The propagation characteristics of leaky surface wave on Li2B4O7 substrate were theoretically calculated for all cuts and propagation directions by changing Eulers angle. The theoretical contour maps for phase velocity, electromechanical coupling constant (K2), temperature coefficient of delay (TCD), propagation loss, and power flow angle (PFA) are displayed. Cuts with good propagation characteristics were theoretically discovered using leaky surface wave.

Acquiring Disaster Prevention Knowledge from Fieldwork Activities in a Region.

There has been increasing awareness of the need for disaster prevention in Japan. The aim of this research is to ascertain whether a basic knowledge of disaster prevention can be acquired through fieldwork learning activities for purposes of creating a disaster prevention map. We developed a disaster prevention learning support system that facilitated the task of recording information at real locations, and then aggregated it. Using this system, we conducted a classroom exercise at a high school to help students identify the kinds of hazards that are likely to develop in specific areas—based on their features—in the event of a large earthquake. After conducting fieldwork, they returned to the classroom. Under the guidance of their teachers, they referred to the information they had recorded and the knowledge they had acquired to postulate a scenario in which a large earthquake occurred. They further assumed that this earthquake had occurred while they were outdoors. The students then devised evacuation measures using paper simulations. The results of this exercise revealed that the knowledge of disaster prevention acquired through this exercise had practical applications.

A Flexible Scenario-Based Mobile Learning System for Disaster Evacuation

Disaster prevention awareness has been growing in Japan since the Great East Japan Earthquake in 2011. This research aimed to improve high school students’ judgments in emergency situations by training through a scenario-based learning support system called “ES3.” Groups of four to five students were presented with a hypothetical earthquake disaster scenario on Android tablets and used their own judgment to navigate routes and shelters throughout the evacuation process. Faced with certain dangers and sites of damage, the students were required to select appropriate responsive actions. During the exercise, learning logs of locations and input values were stored in the server system. Following the exercise, the students discussed their decisions and actions, completing a questionnaire on safety consciousness. The data analysis suggested that the students selected actions, shelter, and evacuation routes using their own subjective judgment, and that the evacuation training increased their consciousness of their own safety.

Cognitive effects of the LV Approach on kanji learners: A novel approach using learner's personal visual cognition

This study focuses on the issue of how kanji learners mentally “deconstruct” a kanji as they view it and how they may update this visual deconstruction over time as they learn kanji. The research problem deals with the question of whether or not an innovative kanji learning approach, the “Learners Visualization (LV) Approach”, assists learners in significantly updating their personal kanji deconstruction visualization (which refers to how the learner visually divides a given kanji into smaller, manageable parts). With the LV Approach, in contrast to other kanji learning approaches, kanji learners themselves decide which way to divide a kanji into smaller parts, allowing them to thus choose the complexity level and number of parts of that particular kanji according to their personal visual cognition. To support the analysis of the kanji visualization process, we developed a kanji learning support system based on the LV Approach. The analysis of our results proves the existence of the positive effect of using this novel approach in kanji learning; learners progressively move towards visually dividing kanji into fewer and fewer blocks.