Solubility of NiO in Al2O3

Solubility of NiO in Al₂O₃ was determined by electron probe microanalysisy A diffusion couple method was used by coupling an NiO-doped Al₂O₃ polycrystal to a pure single crystal of Al₂O₃. The solubility of NiO in Al₂O₃ in air was 230 wt ppm (157 at. ppm of cations) and 170 wt ppm (116 at. ppm) at 2073 and 1973 K, respectively. The solubility of NiO in Al₂O₃ obtained in this work was compared with our previous work of the solubility of MgO in Al₂o₃.     

Perspective on full reusable SSTO aerospace plane research and development in Japan

For the promotion of extended and diversified space activities in Japan, it is required to build immediately the technology bases capable of supporting such space activities and thereby to expand positively international cooperation as one of Japan's roles towards the world's prosperity of the 21st century. Especially, development of the manned space transportation system to and from lower earth orbit is the key issue, requiring an unprecedented approach. The Single Stage to Orbit(SSTO) Aerospace Plane is the unique answer to this issue. This paper will discuss the perspective on the research and development of the Space Plane in Japan. The topics will cover a long range R&D scenario and current activities of the related organizations in Japan.     

Heat pipe based cold energy storage systems for datacenter energy conservation

In the present paper, design and economics of the novel type of thermal control system for datacenter using heat pipe based cold energy storage has been proposed and discussed. Two types of cold energy storage system namely: ice storage system and cold water storage system are explained and sized for datacenter with heat output capacity of 8800 kW. Basically, the cold energy storage will help to reduce the chiller running time that will save electricity related cost and decrease greenhouse gas emissions resulting from the electricity generation from non-renewable sources. The proposed cold energy storage system can be retrofit or connected in the existing datacenter facilities without major design changes. Out of the two proposed systems, ice based cold energy storage system is mainly recommended for datacenters which are located in very cold locations and therefore can offer long term seasonal storage of cold energy within reasonable cost. One of the potential application domains for ice based cold energy storage system using heat pipes is the emergency backup system for datacenter. Water based cold energy storage system provides more compact size with short term storage (hours to days) and is potential for datacenters located in areas with yearly average temperature below the permissible cooling water temperature (∼25 °C). The aforesaid cold energy storage systems were sized on the basis of metrological conditions in Poughkeepsie, New York. As an outcome of the thermal and cost analysis, water based cold energy storage system with cooling capability to handle 60% of datacenter yearly heat load will provide an optimum system size with minimum payback period of 3.5 years. Water based cold energy storage system using heat pipes can be essentially used as precooler for chiller. Preliminary results obtained from the experimental system to test the capability of heat pipe based cold energy storage system have provided satisfactory outcomes and validated the proposed system concept.     

Application and development of synthetic polymer membranes. VI. Pervaporation of aqueous ethanol solution through quaternized poly[3-(N′,N′-dimethyl) aminopropylacrylamide-co-acrylonitrile] membranes

Membranes obtained from polymers, quaternized poly[3-(N′,N′-dimethyl) aminopropylacrylamide-co-acrylonitrile]s, showed selective separation of water from aqueous ethanol solution by pervaporation. The separation factor toward water reached over 15,000. Membrane performance showed a good correlation to membrane polarity. Differential scanning calorimetric melting endotherms of the water-swollen membranes were studied to clarify the state of water in the membranes. The results suggested that there are two states of water in the membrane: bound and free. The higher the fraction of bound water in the membrane, clearly, the more preferentially was water permeated.     

Computer simulation study on the shear-induced phase separation in semidilute polymer solutions in 3-dimensional space

We investigated the shear-induced phase separation and/or concentration fluctuation phenomena in semidilute polymer solution by using computer simulation in 3-dimensional space with Doi-Onuki theory. The enhancement of the concentration fluctuations occurs under shear flow and the scattering function in q_x-q_z plane exhibits the so-called butterfly pattern as observed experimentally, where q_x and q_z are the components of the scattering vector for flow direction and neutral direction, respectively. The time changes in the peak position and the intensity at peak position in the scattering function in q_x-q_z plane can be divided into two regions: the peak position becomes smaller and the peak intensity increases with t, and then the peak position and intensity become constant and the system reaches its steady state. These agree with the experimental results qualitatively. However, the computer simulation results indicate that the peak position at the steady state is almost independent of the shear rate, while the decrease in the peak position at steady state with shear rate has been observed experimentally. This disagreement originates from the use of the simplest constitutive equation in the computer simulation.     

Experimental study on the thermoelastic martensitic transformation in shape memory alloy polycrystal induced by combined external forces

Combined tension and torsion experiments with thin wall specimens of Cu-Al-Zn-Mn polycrystalline shape memory alloy (SMA) were performed at temperatureT =A _f + 25 K. The general stress-strain behaviors due to the thermoelastic martensitic transformation, induced by a combination of external forces of axial load and torque, were studied. It is shown that the progress of martensitic transformation (MT) at general stress conditions can be well considered as triggered and controlled by the supplied mechanical work (a kind of equivalent stress) in the first approximation. Pseudoelastic strains in proportional as well as nonproportional combined tension-torsion loadings were found fully reversible, provided that uniaxial strains were reversible. The axial strain can be controlled by the change of torque andvice versa due to the coupling among tension and torsion under stress, not only in forward transformation, but also in reverse transformation on unloading. The pseudoelastic strains of SMA polycrystal are path dependent but well reproducible along the same stress path. The evolution of macroscopic strain response of SMA polycrystal, subjected to the nonproportional pseudoelastic loading cycles with imposed stress path, was systematically investigated. The results bring qualitatively new information about the progress of the MT in SMA polycrystal, subjected to the general variations of external stress. PETR SITTNER, Research Associate, formerly with the Faculty of Engineering, Mie University     

Improvement of molten core–concrete interaction model in debris spreading analysis module with consideration of concrete degradation by heat

Understanding the situation inside of the reactors at TEPCO's Fukushima Daiichi Nuclear Power Plant and planning of the methods for debris removal are important for decommissioning the reactors. A debris spreading analysis (DSA) module in the severe accident analysis code SAMPSON has been improved and verified to analyze composite phenomena of molten core (debris) spreading on a reactor containment floor and concrete erosion to the inside of the floor by molten core–concrete interaction (MCCI). The primary models in the DSA module were three-dimensional natural convection with simultaneous spreading, melting and solidification in an open space. In addition to these, the analysis capability has been improved to treat phenomena in a closed space, such as debris eroding laterally under concrete floors at the bottom of the sump pit which is done by an advanced method for boundary processing. A buffer cell for flow analysis, which is defined by a different array variable, is arranged in the same coordinates of the concrete cell (structure cell). Mass, momentum, and the advection term of energy between the debris melt cells and the buffer cells are solved. At the same instant, the heat transfer is calculated between the debris melt cells and the structure cells coexisting side by side with the buffer cells. In this study, technical knowledge regarding changes in physical properties due to thermal degradation of concrete was considered for the prediction of erosion rate, and the DSA module with the models noted above was verified by comparison with erosion data of the core–concrete interaction tests in the OECD/MCCI program. The calculated erosion depth, width, and erosion rate under the concrete floor showed good agreement with the test data and the analysis capability of the module was confirmed.     

Effect of Oxygen Adsorption on Adhesion of W to Au Studied by Field Ion Microscopy

A field ion microscope has been used to investigate the influence of oxygen adsorption on adhesion of W to Au. An adhesion contact in ultrahigh vacuum of the field ion microscope was carried out using a W tip either with or without oxygen adsorption. It was found that adhesion force decreased with increasing oxygen exposures up to 60 Langmuirs (L). With an oxygen exposure of 16 L, an intermediate adhesion resulted. Adhesion is thus dependent upon the coverage of oxygen. The depth of adhesion-induced lattice defects was studied using the field evaporation technique. Over 200 L, adhesion force was not detectable, nor was distortion of W atoms.