Microstructure of copoly(3-hydroxyalkanoates) produced in the anaerobic–aerobic activated sludge process

The sequence structures of bacterially synthesized copoly(3-hydroxyalkanoates), isolated from the sludge developed in the anaerobic–aerobic waste-water treatment process containing propionate as a carbon source, were analysed by ¹³C NMR spectroscopy. These copolyesters were composed of four different monomer units, 3-hydroxybutyrate, 3-hydroxyvalerate, 3-hydroxy-2-methylbutyrate and 3-hydroxy-2-methylvalerate. By using water/acetone mixed solvent, one of the copolyester samples was fractionated into fractions by differences in average molecular weights as well as in monomer compositions. The carbonyl carbon resonances, split due to differences in diad sequences, were analysed on the basis of Bernoullian statistics. It is suggested that these copolyesters were mixtures of random copolymers with different monomer compositions.     

Analysis of electromagnetic waveguide bends by three-dimensional finite element method with edge elements

An approach based on the finite element method (FEM) with the rectangular-parallelepipd edge element is proposed for the analysis of electromagnetic waveguide bends. Here, to be permissible for analysis of various electromagnetic waveguides, the analytical relations in the uniform waveguide are constructed numerically by using the FEM with the rectangular edge element. To confirm the validity and versatility of this approach, bends of a hollow waveguide, a half-filled dielectric waveguide, and a finline are analyzed. © 1996 John Wiley & Sons, Inc.     

Numerical study of twin-screw extruders by three-dimensional flow analysis—development of analysis technique and evaluation of mixing performance for full flight screws

We have developed a method for predicting the three-dimensional flow field in the melt conveying zone in counter-rotating and co-rotating twin-screw extruders. We applied this technique to the full flight screws with thin flight width and open C-shaped channels in both rotating type extruders having the same screw configurations. We compared the details of velocity and stress fields, the flow rates of transportation, and various kinds of leakage flows for both rotating type extruders. Also, we obtained the spatial distribution of tracer particles and residence time distribution using a numerical tracer experiment. The flow rate in the transport direction in the co-rotating twin-screw was larger than that in the counter-rotating twin-screw, and this suggested that the latter has higher transport performance when the screws have thin flight width and open C-shaped channels as used in this study. As for the distributive mixing, it was found that the co-rotating twin-screw excels in the area of fluid rearrangement between the two screws and distribution in the rotational direction, while the counter-rotating twin-screw has the desirable characteristic of wide distribution in the axial direction. With regard to dispersive mixing, there was no considerable difference between calculated stress fields in both rotating type extruders.     

Synchronization of voice data on asynchronous networks and its implementation for a VSAT channel gateway

The variation of packet‐arrival intervals is one of the problems to be solved in realizing real‐time voice communications on asynchronous networks such as the Internet. Although the variation can be absorbed by a receiving buffer, the end‐to‐end delay increases in proportion to the amount of buffered data. Therefore, the guideline for the receiving buffer's design that considers the trade‐off between voice quality and delay is needed. In this paper, the design of the receiving buffer by means of the voice‐speed‐conversion technique is discussed. According to our scenario, the buffer size was expected to be equivalent to the time length in which the probability distribution function of the packet‐arrival intervals was about 95% to 99%. However, it is shown that synchronized voice reproduction can be achieved within a preset delay, which is shorter than the corresponding time to the buffer size. This is achieved by keeping the rate of voice speed conversion within the range of 50% to 150% depending on the variation of the intervals. The proposed method was implemented in the conventional UNIX workstations (WSs) connected to an Ethernet segment. The average voice delay between WSs was 150 to 180 ms and the synchronized voice reproduction was achieved with a standard deviation of 13 to 25 ms. The proposed method is applied to VSAT‐satellite‐channel gateways to realize the real‐time voice communication between the WSs through a VSAT channel. © 1999 Scripta Technica, Electr Eng Jpn, 130(2): 68–79, 2000     

Application of virtual machine technology to real-time mapping of Thomson scattering data to flux coordinates for the LHD

This paper presents a system called “TSMAP” that maps electron temperature profiles to flux coordinates for the Large Helical Device (LHD). Considering the flux surface is isothermal, TSMAP searches an equilibrium database for the LHD equilibrium that fits the electron temperature profile. The equilibrium database is built through many VMEC computations of the helical equilibria. Because the number of equilibria is large, the most important technical issue for realizing the TSMAP system is computational performance. Therefore, we use multiple personal computers to enhance performance when building the database for TSMAP. We use virtual machines on multiple Linux computers to run the TSMAP program. Virtual machine technology is flexible, allowing the number of computers to be easily increased. This paper discusses how the use of virtual machine technology enhances the performance of TSMAP calculations when multiple CPU cores are used.     

Flow characteristics of rectangular underexpanded impinging jets

In this paper, the flow fields of underexpanded impinging jet issued from rectangular nozzles of aspect ratio 1, 3 and 5 are numerically and experimentally studied. Two dimensional temperature and pressure distributions are measured by using infrared camera and the combination of a pressure scanning device and a stepping motor, respectively. The variation of the stagnation pressure on the impinging plate reveals that a hysteretic phenomenon exists during the increasing and decreasing of the pressure ratio for the aspect ratio of 3.0 and 5.0. It is also found that the nozzle of aspect ratio 1.0 caused the largest total pressure loss pc / p0 = 0.27 at the pressure ratio of p0 /pb = 6.5, where pc is the stagnation center pressure on the wall, p0 the upstream stagnation pressure, pb the ambient pressure. The other two nozzles showed that the pressure loss pc /p0 =0.52 and 0.55 were achieved by the nozzles of the aspect ratio 3,0 and 5.0, respectively. The comparison between the calculations and experiments is fairly good, showing the three dimensional streamlines and structures of the shock waves in the jets. However, the hysteresis of the pressure variations observed in the experiments between the pressure ratio of 3.5 and 4.5 cannot be confirmed in the calculations.     

Adhesion and detachment characteristics of a TBAB hydrate solid on a heat transfer surface (Effect of concentration of TBAB solutions)

In air‐conditioning systems, it is desirable that the liquid–solid phase change temperature of a cool energy storage material be approximately 10^°C, with respect to improving the coefficient of performance (COP). Moreover, a thermal storage material that forms slurry can realize a large heat capacity of the working fluids. A solid that adheres to the heat transfer surface forms a thermal resistance layer and significantly reduces the rate of cold storage; therefore, it is important to avoid the adhesion of a thick solid layer on the surface so as to realize efficient energy storage. Considering a harvest type cooling unit, the force required for removal of the solid phase from the heat transfer surface was investigated. Tetra‐n‐butylammonium bromide (TBAB) clathrate hydrate was used as a cold storage material and the effect of the TBAB solution concentration on the scraping force required to detach the adhered TBAB hydrate solid from the heat transfer surface was experimentally examined. The TBAB hydrate solids were broadly categorized into two types, and the scraping force required for removal of these two types of TBAB hydrate solid was different. The scraping force required for removal of the solid increased due to the effect of increasing the concentration of the TBAB solution. © 2009 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20254     

Influence of manganese on iron oxyhydroxides and oxides formed in aqueous solution

Structural analysis techniques such as X-ray diffraction and anomalous X-ray scattering were used for characterizing the influence of manganese on iron oxyhydroxides and oxides formed from green rust (GR) in an aqueous solution. The results showed that the formation of Fe₃O₄ was enhanced by the addition of manganese ions during the conversion of GR2 to α-FeOOH and Fe₃O₄. The results obtained from anomalous X-ray scattering showed that manganese was present both in α-FeOOH and Fe₃O₄ particles. The incorporation of manganese in α-FeOOH appears to induce the distortion of the atomic-scale structure of α-FeOOH particles formed in an aqueous solution.     

Lithium ion secondary batteries; past 10 years and the future

Technologies of lithium ion secondary batteries (LIB) were pioneered by Sony. Since the introduction of LIB on the market first in the world in 1991, the LIB has been applied to consumer products as diverse as cellular phones, video cameras, notebook computers, portable minidisk players and others. Years of assiduous efforts and researches to improve LIB performances enabled LIB to play a leading role in the portable secondary battery market. In this article, the past 10 years’ technological achievement is traced and future possibilities are discussed.     

Modeling the phase partitioning behavior of gas tracers under geothermal reservoir conditions

A model of the liquid-vapor phase partitioning behavior of low concentrations of gas tracers in water at geothermal temperatures and pressures is presented. This model uses Henry's coefficient to describe the variation of the gas tracer solubility with temperature and pressure. A new method is described for the determination and representation of Henry's coefficients. The method uses experimentally determined values of Henry's coefficient and a theoretically predicted value of behavior at the critical point of water to provide data that can be fitted by a semi-empirical correlation. No assumptions regarding ideal behavior are necessary. The semi-empirical correlation is a modified version of that presented by Harvey, A. (1996. Semiempirical correlation for Henry's constants over large temperature ranges. American Institute of Chemical Engineers Journal 42(5), 1491-1494) and better accounts for high temperature and non-ideal behavior. Sets of model coefficients are given for a range of possible gas tracers. The resulting phase partitioning model is simple and may be easily implemented in a numerical geothermal simulator. The use and behavior of the model is illustrated by its application to a number of idealised test problems.