Showing papers by "Chiba Institute of Technology published in 1989"

High‐Resolution Electron Microscopy Observations of Stacking Faults in β‐SiC

Abstract: Structural images of the stacking faults in β-SiC were obtained with a high-resolution electron microscope. Stacking faults initially present in β-SiC powder particles were eliminated as grain growth proceeded at elevated temperatures.

Molecular aggregation of PEEK with PES blends and the block copolymers composed of PEEK and PES components

Abstract: Polymer blends of PEEK with PES were prepared by the solution blending method. Copolymers composed of PEEK and PES components were synthesized from these oligomers. The formation conditions exerted an influence over the molecular aggregation and the crystallization behaviors of the blend films and block copolymers which were examined by X-ray diffractometry and DSC analysis. As a result, phase-separation in the blend films was found when the formation temperature was high. The blend films formed at 340°C, quenched and annealed at 180°C, exhibited the same crystallization behavior as those of PEEK. In the case of the blend films formed at 300°C, the annealing of the films at 250°C was required to crystallize the blend films. The Tg of a copolymer with a PEEK component content of more than 50% tends to shift toward a higher temperature than the Tg of PEEK itself, and the Tm of the copolymer toward a lower temperature than that of PEEK ist. Rontgendiffraktometrische Untersuchungen und DSC-Messungen an Blend-Filmen, die aus Losungen von PEEK und PES hergestellt wurden, zeigen eine Phasenseparation bei den Filmen, die bei 340°C hergestellt wurden. Das Kristallisationsverhalten von Filmen, die bei 340°C hergestellt, anschliesend abgeschreckt und bei 180°C getempert wurden, ist identisch mit dem von PEEK. Filme, die bei 300°C hergestellt wurden, kristallisierten erst durch Tempern bei 250°C. Blockcopolymere, die aus Oligomeren von PEEK und PES erhalten wurden, unterscheiden sich in dieser Hinsicht von Blends der gleichen Zusammensetzung. Die Glastemperatur von Copolymeren mit einem PEEK-Gehalt von mehr als 50% liegt hoher als die von PEEK selbst, wahrend der Schmelzpunkt dieser Copolymeren niedriger als der von PEEK ist.

Activities of boron in the binary Fe-B, Co-B, and Cu-B melts

Abstract: Activities of boron in the binary Fe-B, Co-B, and Cu-B melts have been directly determined by the electromotive force (emf) measurement. Boron-saturated liquid Cu-B alloy was used as the reference electrode and a ternary 28 wt pct Al2O3-29 wt pct B2O3-43 wt pct CaO oxide melt was used as the electrolyte. Deviations of the boron activities from Raoult's law have been found largely negative for the Fe-B and Co-B systems but largely positive for the Cu-B system. Boron activities calculated from the literature data have not been in good agreement with the measured data. Activities of iron, cobalt, and copper have been calculated from the obtained boron activities by means of the Gibbs-Duhem equation. Some modifications to the liquidus curves on the Fe-B and Co-B phase diagrams have been presented.

Thermal and viscoelastic behavior of polyetheretherketone/polyethersulfone blends

Abstract: The polymer blends obtained by the solution blending method show a type of compatible polymer blends. The samples obtained by compression molding the polymer blends below the melting point of the polyetheretherketon (PEEK) exhibit dynamic viscoelastic behavior characteristic of compatible polymer blends, but those by compression molding above the melting point of the PEEK show a phase separation in dynamic viscoelastic behavior. Die aus Losung hergestellten Polymermischungen zeigen den Typus der vollmischbaren Polymerlegierungen. Proben, die durch Formpressen der Polymermischungen unterhalb des Schmelzpunkts von Polyetheretherketon (PEEK) erhallten wurden, zeigen ein fur mischbare Polymerlegierungen typisches viskoelastisches Verhalten. Hingegen zeigt sich bei Mischungen, die oberhalb des Schmelzpunktes von PEEK verprest wurden, im dynamisch-viskoelastischen Verhalten eine Phasentrennung.

Chemical characteristics of pond waters in the Labyrinth of southern Victoria Land, Antarctica

Abstract: A large number of fresh water and saline ponds are located in the Labyrinth (77° 33′ S, 160° 50′ E) of the upper Wright Valley in the Dry Valleys region of southern Victoria Land, Antarctica. It is situated near the terminus of the Wright Upper Glacier between 800–1000 m above sea level. From a limnological point of view, the most interesting problems concerning these saline ponds are the origin of their salts and their evolutional history.

Non-linear adaptive control for robotic manipulators with continuous control inputs

Abstract: The problems of constructing non-linear adaptive control systems for robotic manipulators are considered. It is shown that quality dynamic performance can be achieved without exact knowledge of the non-linear terms of robotic manipulators. The control scheme is constructed with at most seven control parameters to be adjusted adaptively, and that number is determined independent of the number of degrees of freedom of the manipulator. In contrast to the VSS approach, continuous control inputs are used instead of discontinuous ones, and the control gains are not fixed but determined automatically. Some simulation results show the effectiveness and simplicity of the proposed method.

The orthogonal projection algorithm for block adaptive signal processing

Abstract: The authors propose a block adaptive algorithm for estimating the impulse response of discrete-time systems and discuss some of its properties. This algorithm, in which the performance measure is the block mean square error (BMSE), consists of block processing and orthogonal projection arithmetic and updates the adaptive filter's coefficients once for each block of data. That is, the algorithm is based on orthogonal projection to the subspace spanned by input vectors corresponding to the block index. Some fundamental theorems are derived with respect to this algorithm, and they are substantiated by computer simulations. >

Approximate theory and characteristics of laser doppler velocimeter using self—mixing effect of semiconductor laser diode

Abstract: To explain the experimental characteristics of a laser Doppler velocimeter using the self-mixing effect of a semiconductor laser diode (LDV) with a rotating disc as a target, a theoretical analysis of a Doppler beat waveform was carried out, and its approximate solution was obtained by using the perturbation method. The theoretical characteristics based on this solution agreed fairly well with the experimental ones. The operating conditions of the LDV required for forming the beat wave into a sawtooth waveform, and the reasons why the sawtooth wave is transformed into a mirror image depending on the sign of the Doppler frequency were found, i.e., the phase angles of the second and third higher harmonics of the beat wave are inverted by the inversion of the direction of rotation. The upper limit of the Doppler frequency and the range of R parameter of the LD were estimated theoretically.

Ferroelectric domains of NaNO2 delineated by liquid crystal method

Abstract: Ferroelectric domains in NaNO2 were investigated by a nematic liquid crystal method. Growing domains under electric field are rhombic prisms surrounded by the crystallographic planes (101) and (101), while static domains are plates parallel to (100). The wall orientation of the static domains is successfully explained by Zhirnov's type continuum theory for equilibrium domain, while the calculation of growing domain shape disagrees with the experimental results.

A Convenient Approach to the Synthesis of Azido-Acyclic Nucleosides

Abstract: The azidation of unprotected acyclic nucleosides (4) was carried out in a one-pot reaction by means of the reagent triphenylphosphine-carbon tetraiodide-sodium azide to give the corresponding mono-azido-acyclic nucleosides (6) in good yields without by-products such as the di-azido-acyclic nucleosides.

Computer simulation for the efficient operation of a CW CO electric discharge laser

Abstract: Optimum conditions for the efficient operation of a cw CO laser excited by transverse dc glow discharge using a gas mixture of CO/N2/He/02 has been investigated by computer simulation. The simulation model combines direct excitation process by electron impact, vibration to vibration ( V-V ) and vibration to rotation/translation ( V-R/T ) energy transfer process, spontaneous and stimulated emission process, and semi 1-dimensional flow model. One of the important experimental problems that the laser power output decreases against the increase in gas flow velocity is analyzed by the simulation. According to the computed results, the problem is not serious if the gas temperature is low enough or sufficient discharge current is applied. The possibility of the high power and efficient laser operation even at around 200 K is predicted by the simulation.© (1989) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Preparation and physical properties of (Bi1−xLnx)2.2Sr1.8CaCu2Oy (Ln=La, Pr and Nd, x≤0.25)

Abstract: Solid solutions (Bi1-xLnx)2.2Sr1.8CaCu2Oy(Ln=La, Pr and Nd, x0.25) were prepared. Of these three Ln ions replacing Bi3+, Pr was not trivalent, the average valence of Pr being shown to be 3.5. With increase of x, the onset of superconducting transition temperature and hole concentration initially increase, then decrease steadily with increase of x equally for all the three series, irrespective of difference in lanthanide elements substituted.

"In-situ" Analysis of High Temperature Gases by Infrared Spectroscopy and Its Application

Abstract: Synopsis : A technique for the \"in-situ\" analysis of the high temperature gases containing CO, CO2, H2O and SiO at 800-1 600•Ž was developed. The gas in the furnace was monitored by a newly developed infrared optical sensor with Fourier Transform Infrared Spectrometer (FTIR). The sensor was of a water cooled probe with various infrared light guide. The experimental results could be summarized as follows ;

Some recent topics in pressure vessel technology

Abstract: This paper, the third memorial lecture for Mr. Robert D. Wylie, reviews the present practices and future trends in pressure vessel technology which have arisen since the 5th International Conference on Pressure Vessel Technology held in San Francisco in 1984. We have made tremendous progress in the various fields of pressure vessel technology during the past four years. Consequently, it is very difficult to review all the topics in this short lecture. Major technical arears covered include some recent topics on ferrous materials, fabrication techniques and life expectancy to assure structural integrity.

Development of the transmission equations using electromagnetic field theory on a transmission line coupled with external fields

Abstract: Researchers in the past initially assumed the existence of transmission line equations in deriving the transmission equations for two parallel lines which are exposed to the external field. They used a method which mixed the theory of electromagnetic fields and the circuit theory. In this paper we do not initially assume the existence of the transmission line equations, nor do we mix the circuit theory. We established one equation of the vector potential on the line from the viewpoint of the field theory. After we introduced the concept of line voltage, it was divided into one pair of two equations concerning the vector potential and the line voltage. Under the assumption that line diameter is sufficiently small, we obtained two equations as one pair for the line current and the line voltage together with the representation of the series inductance and the parallel capacitance as coefficients. These equations are the same as those derived by previous researchers. Strictly speaking, the line current is obtained as the solution of an integral equation. This solution consists of the solutions of the transmission equations and many strongly decreasing higher-order terms according to the distance because of nonzero diameter of the line. However, higher-order terms are in practice, negligibly smaller than the former solutions (for example, of the order of 10-3). Therefore, the forementioned transmission line equations are considered to be correct with a good approximation.

Chapter 6 The Tychonoff Functor and Related Topics

Abstract: Publisher Summary This chapter presents the basic theories of the Tychonoff functor, w-compact spaces, and w-paracompact spaces. The origin of the Tychonoff functor is the complete regularization of general topological spaces. The Tychonoff functor is now recognized as a covariant functor from the category of topological spaces and continuous maps into itself. The concept of w-paracompact spaces follows naturally that of w-compact spaces and is a generalization of paracompact Hausdorff spaces at the same time. The chapter introduces a generalization of the Tamano's theorem. The chapter investigates the characterization of w-paracompact spaces in terms of product spaces, which is parallel to Tamano's theorem for paracompact Hausdorff spaces. All spaces in this chapter are assumed to be general topological spaces.

Pyroelectric imaging on gash

Abstract: Ferroelectric domain patterns of GASH crystals were examined by a pyroelectric probe technique. The pyroelectric signals from the sample capacitor were stored in computer memeorics and read out to display pyroelectric images in desirable modes. The experimental results of the pyroelectric imaging are in good agreement with the patterns revealed by a powder deposition technique. The center segment of the crystal is uni-polar, and the pyroelectric signal intensity level is comparable with that of the outer segment. The statistical variance of the signal intensity spectrum in the center segment is larger than that in the outer segment.

Thermostat for Dynamic Light Scattering Measurements at High Temperatures

Abstract: A simple thermostat of the double-chamber type used to measure dynamic light scattering at temperatures up to 160°C has been developed. A temperature stability of 0.01°C has been accomplished at 160°C. A new refractometer for high-temperature measurements is also described.

Pyroelectric Imaging on the Ferroelectric GASH[C(NH2)3Al(SO4)2·6H2O]

Abstract: Ferroelectric domain patterms of guanidine aluminum sulfate hexahydrate (GASH) were examined by a pyroelectric probe technique, in which the laser beam scanning and data storing were controlled by a microcomputer. It was confirmed that the averaged polarity and the magnitude of pyroelectric signal on the (0001) growth region are equal to those of either (10\bar10) or (01\bar10) growth regions, which are connected by 3-fold inversion symmetry of the crystal. The standard deviation of the pyroelectric signal intensity spectrum in the (0001) region is larger than that in the other regions. The spatial fluctuation of the pyroelectric constant in the (0001) region is larger than 25 µm, which is consistent with the inhomogeneous distribution of the polar region on the spiral patterns revealed by the powder deposition technique.