Design of electric power generation systems using waste heat energy

The recent energy crisis forces engineers to take into account reduction of electricity consumption as well as heat energy consumption in industry. As it is very difficult to save the amount of electricity, they have tried to recover electric power using waste heat energies. In this paper, the possibilities of electric power recovery from waste heat energies are discussed based on the relationship between supply heat sources and demand heat sources in chemical process systems. In solving such problems, the following difficulties appear: calculation of maximum quantity of generated electric power, determination of a suitable working fluid and its temperatures in the Rankine cycle, and so on. The proposed method can solve them using the temperature-enthalpy diagram and, furthermore, has the advantage of being able to design a final heat exchanger network with heat exchangers in a power plant by means of a synthesis method using the same diagram.     

State-of-the-art in research on Mach reflection of shock waves

Reflected shock transition from Mach to regular reflection over wedges and state-of-the-art of Mach reflection research are presented. Examples of shock wave reflection from multiple wedges and curved wedges are given in conjunction with the Mach reflection research.     

Characterization of cellulose acetate in acetone solution. Studies on prehump II in GPC pattern

Cellulose acetate in acetone solution is known to show some peaks in its chromatogram as measured by gel-permeation chromatography. These peaks are named from the shorter elution time as prehump I, prehump II, and main hump. In our previous paper, we characterized prehump I. In this study, the second peak, prehump II, was fractionated by using the large-scale GPC column and its molecular properties were investigated. The results have shown that the molecules of prehump II are not aggregated but molecularly dispersed with some anionic residues. These anionic groups may be sulfuric acid groups introduced during the acetylation process as a catalyst that interact repulsively with the anionic groups of the GPC column gel. This resulted in the phenomenon that the prehump II elutes earlier than the main hump in the GPC chromatogram. © 1993 John Wiley & Sons, Inc.     

Bidirectional fibre optic loop-structured network

A basic bidirectional fibre optic loop-structured network configuration which provides an automatic recovery mechanism against a line failure and employs WDM-TDMA techniques for signal multiplexing is presented. Experimental results of a prototype of such a network are also described.     

Numerical simulation method for elastic-plastic dynamic response for hypervelocity impact phenomena

This study presents a time-dependent numerical method for impact in planar or cylindrical symmetry. We use Eulerian finite-difference scheme, Tilloston's Metallic Equation of state, von Mises Yield criterion, for calculating the large deformation of elastic-plastic high velocity impact. Failure, cavitation and melting of solids are accounted for. The present model treats the formation and evolution of a crater, the deformation of the projectile and the deformation and dynamical response of the target. A two-stage gas gun was employed to experimentally study the phenomena of hypervelocity impact. Good agreement is obtained between the present computational results and craters obtained in experiments of polyethylene/aluminium impacts. The relation of crater shape and penetration depth to dynamic parameters of the projectile and the target is discussed. The Multi Purpose Graphics System (MPGS) is used to describe the calculation results with color graphics.     

Interfacial stability and internal flow of a levitated droplet

Under the microgravity environment, production of new and high quality material is expected. Large droplet is preferable for such a containerless processing in microgravity environment. There are a lot of previous studies for droplet levitation [1]. However, effect of surface instability and internal flow appear remarkable when the droplet becomes large. Elucidation of effect of surface instability and internal flow of the levitated droplet is required for the quality improvement of new material. The objective of present study is to clarify critical conditions of the occurrence of the internal flow and the surface instability. At first, the condition between the stable region and the unstable region of the droplet levitation was evaluated by using the existing critical Weber number theory. The experimental result agreed well with the theory. It was suggested that the stability of droplet can be evaluated by using the theory for the interfacial instability. Finally, two-dimensional visual measurement was conducted to investigate the internal flow structure in a levitated droplet. The effect of physical properties on the internal flow structure of the droplet is investigated by Particle Image Velocimetry (PIV) technique. As the result, it is indicated that the internal flow structure is affected by the physical property such as viscosity.     

Preparation of Terbium Sesquisulfide and Holmium Sesquisulfide by Sulfurization of Their Oxide Powders Using CS_2 Gas

Itiswellknownthatrareearthsesquisulfides(RE2 S3,whereRE =La～Lu)existinseveralpoly morphicstructures[1] .WhileTb2 S3existsintwopoly morphicstructures :αandγ ,Ho2 S3existsinpolymor phicstructure :δandγ[1,2 ] .Theα phasebelongstotheorthorhombicPnmaspacegroup .Theδ phasebe longstothemonoclinicP2 1/mspacegroup .Althoughthethermoelectricandmagneticpropertieshavebeeninvestigatedforα Tb2 S3[3,4 ] ,thosepropertiesarenotofprimaryimportanceforindustry .Incontrast,theγ phase ,whichhasthecu…     

Correlation between the Carbon Nanotube Growth Rate and Byproducts in Antenna‐Type Remote Plasma Chemical Vapor Deposition Observed by Vacuum Ultraviolet Absorption Spectroscopy

For sp² or sp³ carbon material growth, it is important to investigate the precursors or intermediates just before growth. In this study, the density of ethylene (C₂H₄) outside the plasma discharge space and just before reaching the carbon nanotube (CNT) growth region is investigated by vacuum ultraviolet absorption spectroscopy for plasma discharge in an antenna‐type remote plasma chemical vapor deposition with a CH₄/H₂ system, with which the growth of very long (≈0.5 cm) CNT forests is achieved. Single‐wall CNT forests have the potential for application as electrodes in battery cells, vertical wiring for high current applications, and thermal interface materials. It is observed that the plasma discharge decomposes the CH₄ source gas and forms C₂H_x species, which reversibly reform to C₂H₄ in the plasma‐off state. In addition, the density of the formed C₂H₄ has a strong correlation to the CNT growth rate. Therefore, the C₂H₄ density is a good indicator of the density of C₂H_x species for CNT growth in the CH₄/H₂ plasma system.