PRESENT STATUS OF POWDER TECHNOLOGY EDUCATIONAL PROGRAMS AND RESEARCHES IN JAPAN

Tables to indicate the present status of powder technology educational programs in Japan are presented on the basis of a questionnaire style investigation by the Society of Powder Technology, Japan. Research activities in universities and research institutes are also included in the tables.

The activities of both the Society of Powder Technology and the Association of Powder Process Industry and Engineering in Japan are also introduced by explaining their organizations and annual events.     

A contour mode resonator with arched interdigital electrodes

A square plate resonator of contour mode is described in a low frequency operation. The resonator has four-part arched interdigital electrodes (IDEs) on one surface of a piezoelectric ceramic plate. The IDEs are used both for the poling treatment and the excitation of the vibration. Three modes are excited according to the combination of polarization for driving the IDEs, which are the antisymmetrical-antisymmetrical (AA) mode, the antisymmetrical-symmetrical mode (AS), and the symmetrical-symmetrical (SS) mode. The AA mode resonator is obtained in a single mode operation around 256 kHz under a condition for mechanical support.     

Texture and Pectic Composition Differences in Raw, Cooked and Frozen-Thawed Chinese Cabbages due to Leaf Position

Differences in texture of raw, cooked and blanched-frozen-then-thawed Chinese Cabbages and their leaf positions (10, 20, 30, 40, or 50th midribs from the outside) were investigated. Firmness and rupture strain of raw midribs were low, but increased after short cooking time. Crispness of tissues decreased and elasticity increased. The 20–30th midribs were slowest to soften during cooking, while the inner midribs from the 40th were more readily softened. The 40th contained more high methoxyl pectin than did the 20th. Therefore, they were more quickly softened because of pectic release by transelimination. After freezing-thawing, firmness decreased and rupture strain increased. Midribs with firmer texture contained more pectin. After freezing-thawing, amounts of pectin in midribs decreased.     

Imperfect debugging models with fault introduction rate for software reliability assessment

In general it is considered to be unrealistic in software reliability modelling to assume that the faults detected by software testing are perfectly removed without introducing new faults. In this paper we propose two software reliability assessment models with imperfect debugging by assuming that new faults are sometimes introduced when the faults originally latent in a software system are corrected and removed during the testing phase. It is assumed that the fault detection rate is proportional to the sum of the numbers of faults remaining originally in the system and faults introduced by imperfect debugging. These two models are described by a nonhomogeneous Poisson process. Several quantitative measures for reliability assessment are derived, and the maximum likelihood estimations of unknown model parameters are presented. Finally, numerical examples of software reliability analysis based on these two models are shown.     

A non-linear optimization model for water treatment planning of a river basin

The primary objective of this study is to develop a long-range planning model for water treatment management of a river basin.

In order to satisfy environmental standards concerning river water pollution, it is fundamentally necessary to construct area-wide sewerages and sewage treatment plants. Hero, an optimal planning problem to construct these public sewage treatment systems is formulated as a non-linear optimization one. In addition the water supply planning problem is taken into consideration by assuming that waste water treated by public tertiary treatment plants can be roused for industrial purposes. The objective function adopted in this model is the total cost of both construction and operation necessary for public sewage treatment systems, and the optimal solution which minimizes this objective function is determined using the generalized reduced gradient (GRG) algorithm.

Through the study of the Yodo river basin in Japan, it is ascertained that various information necessary for planning can be obtained from the model developed in this study.     

Time optimal control of linear systems with a terminal region

In this paper we formulate a time optimal control problem for a continuous time linear system with a terminal region by the method based on functional analysis and present its solution. The solution is obtained from the results of a minimization of a convex function that is solved by a digital computer. Numerical results of an example system are shown for the two cases of amplitude constraint and energy constraint on control inputs.     

Electrical properties of Sb2O3–CaO–V2O5 glasses and glass-ceramics

The d.c. conductivity (σ) of (a) glasses prepared by the press-quenching method and (b) glass-ceramics (crystallized glass) produced by post-heat treatment was investigated in the system Sb₂O₃–CaO–V₂O₅ and their conduction mechanism was studied. The glasses were n-type semiconductors with σ = 2.6 × 10^-6 ∼ 2.8 × 10^-5 S cm^-1 at 333 K for varying glass compositions. The conduction was attributed to small polaron hopping in the adiabatic regime. The estimated carrier density was 1.7 ∼ 3.8 × 10²¹ cm^-3 for V₂O₅ = 70 ∼ 80 mol% and the mobility was 3.5 × 10^-9 to 6.9 × 10^-8 cm² V^-1 s^-1. Crystallization raised the conductivity by a factor of 10³. The crystalline product in the glass-ceramics was Ca_0.17V₂O₅. The glass-ceramics were n-type semiconductors, and the conduction was interpreted by a superposition of the small polaron hopping in the crystalline and glassy phases. This revised version was published online in November 2006 with corrections to the Cover Date.     

Method of Shortening Settling Time Using Final State Control for High‐Precision Stage with Decouplable Structure of Fine and Coarse Parts

High‐precision stages require high‐speed and high‐precision control to improve their production throughput and quality. However, their motion speed and accuracy are expected to reach a limit in the near future if the conventional high‐precision stage structure is used. Therefore, the authors designed and fabricated a “catapult stage,” which has a structure that can be decoupled into a fine stage and coarse stage. The catapult stage is different from conventional dual stages in which the fine stage is disturbed by the coarse stage because they contact each other. This paper proposes a novel control system design for the catapult stage and a control method that shortens the settling time by using final state control (FSC). So far, FSC has mainly been used for applications such as hard disk drives, for which the initial states are zero. However, it is important to consider the initial states for the catapult stage because the initial position, velocity, and acceleration of the catapult stage are not equal to zero. Simulations and experiments were performed to demonstrate the effectiveness of the proposed methods.     

Texture and Histological Structure of Carrots Frozen at a Programmed Rate and thawed in an Electrostatic Field

To investigate the most suitable rate of freezing and method for thawing, raw and blanched carrots were frozen with LN₂ (freezing rate: –5°or -2°C/min, final temp: -30°C) using a program freezer (PF), or were frozen using conventional freezers (F: -80°C, -30°and -20°C). Then, they were thawed in five different ways: electrostatic thawing (ET, -3°C, 17 hr); -3°C, 17 hr; 5°C, 17 hr; 20°C, 30 min; 100°C, 3 min. Firmness of thawed carrots and amount of undamaged tissues by LM and TEM observations were greatest to least: PF -5°C/min < PF-2°C/ min <-80°C CF<-30°CF<-20°CF, and ET ≧-3°< 5°< 20°< 100°C, respectively. Results suggest the optimum rate of freezing was -5°C/ min. The frozen disks were defrosted comparatively fast even at -3°by ET. Drip, cell damage and softening of disks were prevented by ET.     

Lamb wave device using PbZrO3-based ceramic substrate

A Lamb wave device using a PbZrO₃ abased piezoelectric ceramic substrate and its application to an oscillator are described. The Lamb wave device which is practically in single-mode operation uses the zeroth-order symmetrical (S₀ ) mode. A delay line oscillator is composed of the S₀ mode device, an amplifier and an electrically controllable phase shifter, whose oscillation frequency varies with the applied voltage. The oscillator has fine frequency modulation characteristics in a wide frequency range from DC to 100 kHz. The device performance is useful for FM signal processing or voltage sensing.