Characteristics of adsorption and biodegradation of dissolved organic carbon in biological activated carbon pilot plant

The dissolved organic carbon (DOC) properties for the influent of the BAC pilot plant have shown a 42% biodegradable fraction and a 58% non-biodegradable fraction. The biodegradable dissolved organic carbon (BDOC) was degraded entirely by biodegradation; the removal efficiency was 65–83%. The BDOC removal efficiency at empty bed contact time (EBCT) 15 minutes was larger than at EBCT 8 minutes. At increasing EBCT, a more slowly biodegradable fraction of BDOC (H₂) was utilized. The non-biodegradable dissolved organic carbon (NBDOC) was removed mostly by adsorption, and the removal amount was 24–58%. Therefore, the DOC was removed by adsorption and biodegradation; the removal efficiency by biodegradation was 31%, and that by adsorption was 24%. The breakthrough behaviors of DOC and NBDOC continued to be saturated as the bed volume increased, whereas the BDOC breakthrough curves maintained a certain ratio according to the bed volume.     

Implementation of frequency-shaped tip reference in conjunction with learning controller for improved tip-tracking control

In the flexible manipulator control, tip-tracking control of flexible manipulator results in non-colocated control problem, which has a non-minimum phase dynamic characteristic. The level of tip-tracking performance in the non-colocated control system depends on the characteristics of the tip reference trajectory to be followed, as well as on the characteristics of the flexible manipulator system itself. In a previous research the use of a tip reference trajectory, filtered by a properly designed time-delay command shaping filter, has been proposed and a multirate repetitive learning control (MRLC) has been used as the tip-tracking controller. The practical implementation of this approach, however, requires estimation of the tip position, which is not easy to obtain. In this paper, a practical implementation of the approach is considered and the tip position is estimated with a fourth-order Kalman filter. The experimental results show that, with the use of Kalman filter, the proposed scheme results in a drastic reduction in residual tip vibrations and the required actuation effort. This paper was presented at the 4th Asian Conference on Multibody Dynamics(ACMD2008), Jeju, Korea, August 20–23, 2008. Joo Han Park received his B.S. and M.S. degrees in mechanical engineering from the Kyung Hee Univ., Korea, in 2005 and 2007, respectively. He is currently a Ph.D. candidate in Kyung Hee Univ., Korea. His research interests include robotics and vibration control. Soon Geul Lee received his B.S. degree in Mechanical Engineering from Seoul National Univ. in 1983 and M.S. degree from KAIST in 1985. He received his Ph.D. degree in mechanical Engineering from U. of Michigan, Ann Arbor in 1992. He is currently a Professor at the Dept. of Mechanical Engineering in Kyung Hee Univ., Korea. Sungsoo Rhim received his B.S. and M.S. degrees in Mechanical Engineering from Seoul National Univ., Korea, in 1990 and 1992, respectively. He received his Ph.D. degree in mechanical engineering from Georgia Institute of Technology in 2000. He is currently an Assistant Professor at the Dept. of Mechanical Engineering in Kyung Hee Univ., Korea.     

Pervaporation separation and swelling measurement of acetic acid-water mixtures using crosslinked PVA membranes

The pervaporation separation and the swelling behavior of acetic acid-water mixtures were investigated at 30, 40, and 50°C using the crosslinked poly(vinyl alcohol) (PVA) membranes with varying the poly(acrylic acid) (PAA) contents and the acetic acid concentration in the feed mixture. Typically, for the pervaporation separation of 90 wt % acetic acid in the feed, the PVA/PAA = 75/25 membrane gives the separation factor of 795 and the flux of 5.6 g/m² h at 30°C, respectively. The swelling degree decreases as the PAA content in the membrane decreases to 20 wt % of PAA due to the increase of the crosslinking portion in the membrane and increases beyond this PAA content. The swelling degrees show fairly high at the operating temperatures and the total range of the liquid mixtures in question. The overall activation energy of permeation was also calculated using an Arrhenius type relationship. From this study, it could be concluded that the diffusion step is dominant over the sorption step. © 1997 John Wiley & Sons, Inc.     

Gas‐transport properties through cation‐exchanged sulfonated polysulfone membranes

Sulfonated polysulfone (SPS) membranes were prepared, and the gas‐transport properties of the resulting ionic polymers were examined. Gas‐transport measurements were made on dense films of these polymers with a continuous flow technique. The sulfonation of polysulfone and the metal‐cation exchange of SPS were confirmed with Fourier transform infrared spectroscopy and electron spectroscopy for chemical analysis. The SPS membranes exchanged with the monovalent metal ions showed higher permeability coefficients than the SPS membranes exchanged with the multivalent metal ions, whereas the selectivities of all the metal‐cation‐exchanged sulfonated polysulfone (MeSPS) membranes for O₂/N₂ and CO₂/N₂ gas pairs were higher than those of SPS membranes. When the MeSPS membranes with metal cations of similar ionic radii were compared, the ideal selectivities of O₂/N₂ and CO₂/N₂ through MeSPS with divalent cations were higher than those through MeSPS with monovalent cations. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2611–2617, 2002     

Punching of Ultra Small Size Hole Array

This paper presents a method by which multiple holes of ultra small size can be punched simultaneously. Silicon wafers were used to fabricate punching die. Workpiece used in the present investigation were the rolled pure copper of 3um in thickness and CP titanium of 1.5um in thickness. The metal foils were punched with the dies and arrays of circular and rectangular holes were made. The diameter of holes ranges from 2-10um. The process set-up is similar to that of the flexible rubber pad forming or Guerin process. Arrays of holes were punched successfully in one step forming. The punched holes were examined in terms of their dimensions, surface qualities, and potential defect. The effects of the die hole dimension on ultra small size hole formation of the thin foil were discussed. The optimum process condition such as proper die shape and diameter-thickness ratio (d/t) were also discussed. The results in this paper show that the present method can be successfully applied to the fabrication of ultra small size hole array in a one step operation.     

Multibody dynamics in arterial system

There are many things in common between hemodynamics in arterial systems and multibody dynamics in mechanical systems Hemodynamics is concerned with the forces generated by the heart and the resulting motion of blood through the multi-branched vascular system The conventional hemodynamics model has been intended to show the general behavior of the body arterial system with the frequency domain based linear model The need for detailed models to analyze the local part like coronary arterial tree and cerebral arterial tree has been required recently Non-linear analysis techniques are well-developed in multibody dynamics In this paper, the studies of hemodynamics are summarized from the view of multibody dynamics Computational algorithms of arterial tree analysis is derived, and proved by experiments on animals The flow and pressure of each branch are calculated from the measured flow data at the ascending aorta The simulated results of the carotid artery and the ihac artery show in good accordance with the measured results     

Moisture readsorption and low temperature oxidation characteristics of upgraded low rank coal

This study investigated the behavior of upgraded low rank coal produced by a coal-oil slurry dewatering process regarding moisture readsorption, low temperature oxidation, and spontaneous combustion. The upgraded low rank coal had higher heating values than raw coal. It also showed lower moisture readsorption than raw coal and had less susceptibility to low temperature oxidation and spontaneous combustion. This seemed to result from the coating of the asphalt on the surface of the coal, which covered fine pores and suppressed the active functional groups from reacting with moisture and oxygen in the air. The increasing upgrading pressure negatively affected the moisture readsorption, low temperature oxidation, and spontaneous combustion.     

Vertical nanowire probes for intracellular signaling of living cells

The single living cell action potential was measured in an intracellular mode by using a vertical nanoelectrode. For intracellular interfacing, Si nanowires were vertically grown in a controlled manner, and optimum conditions, such as diameter, length, and nanowire density, were determined by culturing cells on the nanowires. Vertical nanowire probes were then fabricated with a complimentary metal-oxide-semiconductor (CMOS) process including sequential deposition of the passivation and electrode layers on the nanowires, and a subsequent partial etching process. The fabricated nanowire probes had an approximately 60-nm diameter and were intracellular. These probes interfaced with a GH₃ cell and measured the spontaneous action potential. It successfully measured the action potential, which rapidly reached a steady state with average peak amplitude of approximately 10 mV, duration of approximately 140 ms, and period of 0.9 Hz.     

Rehydration kinetics of vacuum-dried Salicornia herbacea

Rehydration kinetics of Salicornia herbacea prepared by vacuum drying at 70 or 80°C was studied at water temperature of 30, 60, and 90°C, respectively. A 2-term 5-parameter exponential decay model was used to describe the rehydration process. The rehydration times for the S. herbacea to reach maximum water absorption (t _M ) at each rehydration condition varied depending on the rehydration temperature and the drying air temperature. The inverse of the time (1/t _M ) showed linear temperature dependency as described by the Arrhenius-type relationship. The activation energy values for the S. herbacea dried at 70 and 80°C were 17.66 and 21.06 kJ/mol, respectively.