Sintering Kinetics at Isothermal Shrinkage: II, Effect of Y2O3 Concentration on the Initial Sintering Stage of Fine Zirconia Powder

The shrinkage behavior of fine zirconia powders containing 2.9 and 7.8 mol% Y₂O₃ was investigated to clarify the effect of Y₂O₃ concentration on the initial sintering stage. The shrinkage of powder compact was measured under both conditions of constant rates of heating (CRH) and constant temperatures. CRH measurements revealed that when the Y₂O₃ concentration of fine zirconia powder increased, the starting temperature of shrinkage shifted to a high temperature. Isothermal shrinkage measurements revealed that the increase in Y₂O₃ concentration causes the shrinkage rate to decrease. The values of activation energy ( Q ) and frequency-factor term (β₀) of diffusion at initial sintering were estimated by applying the sintering-rate equation to the isothermal shrinkage data. When the Y₂O₃ concentration increases, both Q and β₀ of diffusion increase. It is, therefore, concluded that the increase in Y₂O₃ concentration of fine zirconia powder decreases the shrinkage rate because of increasing Q of diffusion at the initial stage of sintering.     

Promotion of hydrogen permeation on metal-dispersed alumina membranes and its application to a membrane reactor for methane steam reforming

A mesoporous membrane for selective separation of hydrogen was prepared usingthe sol-gel method. Some metal salts such as RuCl₃, Pd(NH₃)₄Cl₂, RhCl₃,, and H ₂PtCl₆, were added to the boehmite sol and coated on a porous alumina substrate before firing at 500°C. It was foundthat the permeability of hydrogen and the separation factor for a hydrogen-nitrogen gaseous mixture of these metaldispersed membranes exceeded the limitations of the Knudsen diffusion mechanism. Although the gas permeation through a neat alumina membrane is governed by the Knudsen diffusion, the metals dispersed in alumina membranes were effective in promoting hydrogen permeation. These metaldispersed alumina membranes were also used in a membrane reactor for methane steam reforming at low temperature. In the temperature range of 300 to 500°C, the membrane reactor attained a methane conversion twice as high as the equilibrium value of the packed bed catalytic reactor system as a result of the selective removal of hydrogen from the reaction system.     

Anode‐voltage‐control circuit for compensation of luminance deterioration

Abstract— An external driving circuit that has realized long lifetime, power‐consumption control, and peak luminance for organic light‐emitting diode (OLED) displays have been developed. This circuit realizes an effective method for constant‐anode‐voltage (CV) driving refered to as clamped inverter (CI) driving. The feature of CV driving is to achieve low‐power consumption compared with constant‐anode‐current (CC) driving and to control the power consumption and peak luminance according to the image because display luminance can be easily changed by controlling the anode voltage. On the other hand, CV driving has the problem that luminance deterioration appears to be serious compared with that of CC driving because the current of the OLED element decreases according to usage time. To cope with this, a lifetime compensation circuit that has increased the anode voltage so that it compensates for the luminance deterioration has been developed. This circuit can compensate not only the decrease in current but also the decrease in luminance at a constant current that CC driving cannot. However, increasing the anode voltage causes an increase in stress on the OLED element. The influence of stress on OLED lifetime was verified. As a result, it was confirmed that this circuit can extend the lifetime by 32% even if the anode voltage is increased, causing stress on the OLED structure.     

Correction of color information of a 3D model using a range intensity image

Most active optical range sensors record, simultaneously with the range image, the amount of light reflected at each measured surface location: this information forms what is called a range intensity image, also known as a reflectance image. This paper proposes a method that uses this type of image for the correction of the color information of a textured 3D model. This color information is usually obtained from color images acquired using a digital camera. The lighting condition for the color images are usually not controlled, thus this color information may not be accurate. On the other hand, the illumination condition for the range intensity image is known since it is obtained from a controlled lighting and observation configuration, as required for the purpose of active optical range measurement. The paper describes a method for combining the two sources of information, towards the goal of compensating for a reference range intensity image is first obtained by considering factors such as sensor properties, or distance and relative surface orientation of the measured surface. The color image of the corresponding surface portion is then corrected using this reference range intensity image. A B-spline interpolation technique is applied to reduce the noise of range intensity images. Finally, a method for the estimation of the illumination color is applied to compensate for the light source color. Experiments show the effectiveness of the correction method using range intensity images.     

Photo-regulated metal coordination of azobenzene polymer having sterically controlled ion binding sites

Summary 2,2-Dimethylazobenzenes having metal chelating ligands at meta-positions were synthesized, and the interaction with metal ions were estimated for syn- and anti-ligands on thermal isomerization. The azobenzenes with the metal-interaction were transformed to vinyl azobenzenes and copolymerized with styrene. The metal extracting ability was found in photo-isomerized polymer having syn-bis(iminodiacetic acid) groups; the selectivity was high for Cu(II) ion.     

Evaluation of vector magnetic property in a three-phase induction motor model core with visualization of streamline

In this paper, a streamline display method for magnetic flux density and magnetic field strength vectors in a three-phase induction motor model core is presented, and the relationship between streamlines and magnetic properties is investigated. It is possible to visualize the vector magnetic properties distribution by representing the magnetic flux density and the magnetic field strength vector with the streamlines. In addition, the time variation of the streamlines of the magnetic flux density and magnetic field strength vectors, and magnetic energy was compared. It was clear that the magnetic energy did not necessarily increase in the areas where the magnetic flux density and magnetic field strength increased because these vectors have the spatial phase difference.     

Development of fault cause estimation method for distribution line

We are planning to develop the new Advanced Distribution Automation System (ADAS) equipped with optical communication network and sectionalizer with sensor for more grid reliability and efficiency on maintenance operation. The new system is featured with the function of fault cause or damaged part estimation. The new sectionalizer captures the waveform of electrical line surge originated by fault and the system analyzes the waveform for this function. This paper mainly introduces the system configuration of ADAS and an early stage examination of fault cause estimation technology.     

Prototyping and modeling of the centrifugal casting process for paraffin waxes

Centrifugal casting is a technology used for manufacturing hybrid rocket paraffin grains. This technology helps avoiding voids formation inside the solid paraffin as it cools. Voids are formed because of air bubbles being entrapped while pouring and because the liquid wax shrinks by 17–19% upon cooling. In this work, the centrifugal casting process for the manufacturing of paraffin cylinders was prototyped at two different scales considering critical casting issues. The effects of process parameters (rotational speed, melt temperature, and flow rate) on the tensile properties of the manufactured grains were analyzed. The results of the optimization conducted at the lower scale (2.5?kg) were up scaled to manufacture 25?kg grains. The resulting mechanical properties complied with the design specifications, and they were better than those characterized from the gravity cast wax. A numerical model of growth and dissolution of bubbles during the process was then developed to predict the quality of the castings. The numerical results showed how increasing the mold rotational speed up to 1800?rpm reduced the removal time. However, compared to grains solidification time, the predicted removal times were much shorter, proving the advantage of centrifugal casting in counteracting voids formation.     

Virtual segment: Store–carry–forward relay-based support for wide-area non-real-time data exchange

We have proposed the concept of the virtual segment (VS), in which a global communication service is provided by combining a store–carry–forward scheme using vehicles with broadband wireless/wired network infrastructures along roads connected to the Internet. The VS can be a practical framework for non-real-time, asynchronous message transfer (especially for large messages) in a cost-effective manner. In this study, a critical implementation design issue, the message forward scheduling, in the VS approach is discussed and investigated through computer simulation by our developed VS simulator that has reflected the results of the field experiment for realistic performance evaluation.