The growth of pinholes generated in coated films of adhesives was simulated numerically. Rheological properties of the adhesives were approximated by a power-law model. The motion of the interface of the adhesives was traced by a VOF method. Simulated results were in good agreement with experimental ones. The growth rate was proportional to the inverse of Ohnesorge number and therefore decreases when the viscosity of the adhesives is high and the surface tension is low.
This study aims to develop a technique for preparing stable magnetorheological (MR) fluids using a low-molecular organogelator, N,N′,N″,N′″-1,2,4,5-tetra alkyl/alkenyl pyromellitamide (PMDA-R), with poly-α-olefin as a base oil. The rheological properties and stability of the MR fluids prepared were evaluated through three stability tests: an oil separation test, a static stability test, and a centrifugal separation test. PMDA-R with oleyl and 2-ethylhexyl was found to markedly improve the stability of MR fluids. The relation between the results of the centrifugal separation test and the rheological properties was also examined.
Chitosan film was prepared by the casting method using chitosan dissolved in acetic acid solution, then immersed in an alkaline solution, washed well with distilled water and dried. To adsorb gold ions, the dried film was immersed in 0.1 M NaCl solution containing 1,000 ppm of gold. The film with adsorbed gold ions was then dried, and gold was desorbed using various aqueous solutions containing a reductant. The gold ions were desorbed from the chitosan film as solid nanoparticles of gold. The morphology of the particles depended on the kind of reductant and reduction time but was independent of the concentration of reductant.
We have developed a performance evaluation system for industrial plants that uses data clustering technology. The proposed system, which can be used to analyze plant operational data by using a key performance indicator (KPI), consists of a data-clustering function for operational data with the KPI and a visualization function of clustered results. The data-clustering function is based on the ART2 network, one of the adaptive resonance theory (ART) networks. It can correlate plant operational data to the KPI by classifying the operational data. By using an improved data-clustering algorithm in which different vigilance parameters can be set for each category, the operational data can be classified into fewer categories, thus improving the clustering performance. The visualization function of clustered results illustrates the relation between operational data and the KPI by using a 3D graph with a z-axis indicating the KPI and an x-y plane showing where the gravity centers of the categories are mapped by multidimensional scaling (MDS). By implementing these functions, the system models and visualizes the relation between categories and KPI on a 3D graph.
The effect of heating temperature was examined on the regeneration of activated carbon using supercritical CO2 (ScCO2) assumed to be performed in the exhaust facilities of semiconductor production factories. Experiments were carried out with propylene glycol monomethyl ether (PGME) and propylene glycol monomethyl ether acetate (PGMEA) as model VOC components because of their practical importance. Model samples of used activated carbon were prepared by heating at 200–300°C for 1–63 h under an argon atmosphere after immersion in liquid PGME or PGMEA solvent. Thermogravimetric analyses (TGA) showed that high boiling point adsorbates (400–900°C) were not observed after heating at 200°C but were clearly observed after heating at 250°C or above in the activated carbon with PGME. In the activated carbon with PGMEA, high boiling point adsorbates were not observed after heating at 250°C but were observed after heating at 300°C. These high boiling point adsorbates were not removed from activated carbon by ScCO2 regeneration. This study suggested that high boiling point adsorbates were produced from PGME, PGMEA by heating at higher temperatures, whereas heating at 200°C suppressed their formation and supported the possibility of a high efficiency ScCO2 process.