On the estimation of stochastic sensitivity for non-linear dynamical systems in state estimation problems†

This paper consists of two main parts. Recognizing the existence of identification errors due to variations of system parameters, the first part is devoted to the verification of the existence of a unique continuous solution of a non-linear vector stochastic differential equation with a random parameter and to the establishment of the stochastic sensitivity equation. Both the a and β-stochastic sensitivity equations are established through the precise definition of stochastic sensitivity.

The remainder of this paper deals with evaluation of quantitative aspects of the sensitivity in the state estimation by using the stochastic sensitivity equation.     

A highly temperature-dependent Lamb-wave delay line,using PVF2

A PVF₂ Lamb Wave delay line is described. The transducer consists of o group of three electrodes on two surfaces of a thin film. The output voltage of the Lamb wave device is highly temperature-dependent.     

Controlled Crystallization of Amorphous Si3N4by Ti and CI Additives

Thin films of amorphous Si₃N₄ were prepared by the rf-sputtering method, and the effects of titanium and chlorine additives on its crystallization were examined. When Ti-doped amorphous Si₃N₄ was heated, TiN precipitated at >1100°C; the TiN precipitates promoted the conversion of amorphous Si₃N₄ to β-Si₃N₄. Chlorine led to preferential conversion of amorphous Si₃N₄ to α-Si₃N₄.     

Surface-acoustic-wave frequency-to-voltage converter

A frequency-to-voltage conversion technique is described by using a surface-acoustic-wave delay line with three interdigital transducers, one for input and two for output. Two output signals have a phase difference corresponding to different delay lengths, which are detected as a frequency-to-voltage converted signal via a differential amplifier. The operational principle as a discriminator is reported together with successful experimental results. This type of frequency-to-voltage converter is valid in a number of applications where high frequency is an important consideration.     

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.     

Dietary Flavonoids as Potential Natural Biological Response Modifiers Affecting the Autoimmune System

In vitro anti-complement activity of 19 phenolic compounds was evaluated in the classical pathway. Two flavonoids, epigallocatechin gallate and myricetin, exhibited marked anti-complement activities with IC₅₀ values of 4.2 and 5.2 μg/mL (concentration causing 50% inhibition of complement activity), respectively. The two flavonoids appeared to interact with both antibody-sensitized erythrocytes and complement components to inhibit the cascade reactions in the classical pathway of the complement system. The flavonoids may function as natural biological response modifiers by multiple mechanisms including anticomplement effects. Dietary flavonoids may thus affect the body's autoimmune system.     

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.     

Improved water resistance in edible zein films and composites for biodegradable food packaging

Zein, corn prolamine, was dissolved in several organic solvents to make films and their properties were examined. Ethanol with 20% water and acetone with 30% water were found to dissolve zein well and transform it into a transparent flexible film after moderate drying. Both films showed similar breaking strength to that of commercial thin film of polyvinylidene chloride for food use and were digested with proteases. Only the film prepared from acetone solution showed a relatively low water permeability. This water permeation was found to depend strongly on the rate of diffusion. 1,2-Epoxy-3-chloropropane (ECP) was added into the acetone solution to cross-link the zein molecules for the purpose of improving the breaking strength and water-resistant properties of the film. Alpha-chymotrypsin was found to digest the film even after the modification with ECP. However, this cross-linking resulted in little improvement in the water-resistant properties of the film and also reduced its flexibility.     

An approximate method of state estimation for non-linear dynamical systems with state-dependent noise†

In this paper a method of stochastic linearization is demonstrated for the purpose of establishing an approximate approach to solve filtering problems of non-linear stochastic systems with state-dependent noise in a Markovian framework.

The models of both the dynamical system and the observation process are described by non-linear stochastic differential equations of Itô type.

The principal line of attack is to expand the non-linear drift term into a certain linear function with coefficients which are determined under the minimal squared error criterion. Two methods of linearization are developed for the non-linear diffusion term. The linearized models are thus characterized by expansion coefficients dependent on both the state estimate and the error covariance.

A method is given for the simultaneous treatment of the approximate structure of state estimator dynamics and of the running evaluation of the error covariance, including quantitative aspects of sample path behaviours obtained by digital simulation studies.