1,721,026 research outputs found
NITRIC-OXIDE CHEMISORPTION AND TEMPERATURE-PROGRAMMED DESORPTION STUDY OF COBALT AND MOLYBDENUM CATALYSTS SUPPORTED ON ACTIVATED CARBON AND ALUMINA
No full textA novel fabrication method of a microneedle array using inclined deep x-ray exposure
No full textWe investigated a novel fabrication method of a microneedle array. In microneedle fabrication methods employed to date, researchers have used conventional silicon-based fabrication methods such as inductively coupled plasma etching and wet etching techniques. However, these processes are not sufficient for the fabrication of a longer needle shank and applications such as blood extraction from the skin surface. Using a deep x-ray, high-aspect-ratio (HAR) 3D microstructures can be fabricated. The fabrication process consists of a vertical deep x-ray exposure and a successive inclined deep x-ray exposure. The first vertical exposure makes a triangular column array with a needle conduit through a deep x-ray mask having a triangular and hollow circle shape pattern. The column array is shaped into the microneedle array by the second inclined exposure without additional mask alignment. Changing the inclined angle and the gap between the mask and polymethylmet-acrylate (positive photoresist) substrate, different types of microneedle arrays are fabricated. The fabricated microneedle fulfills the structural requirements for painless drug delivery and blood extraction including a 3D sharp tapered tip, HAR shanks, small invasive surface area and an out-of-plane-type structure. In a skin puncture test, the microneedle array penetrates the skin of the back of the hand without tip breaking
CHARACTERISTICS OF BIMETALLIC COBALT AND MOLYBDENUM CATALYSTS SUPPORTED ON ACTIVATED CARBON OR ALUMINA IN HYDRODESULFURIZATION
No full textA series of bimetallic cobalt (Co) and molybdenum (Mo) catalysts supported on activated carbon or alumina were prepared, and their activities in thiophene hydrodesulfurization and ethylene hydrogenation were compared. The nitric oxide (NO) chemisorption and temperature programmed desorption (TPD) were used to characterize the nature of the synergistic active sites. Carbon supported catalysts also demonstrated the synergism in activity, which is well known for alumina supported catalysts. The specific activity and the adsorption stoichiometry of each site were interpreted from NO chemisorption. The possibility of NO as a probe molecule for sulfide catalysts was provided by the present work
HYDRODESULFURIZATION OF THIOPHENE OVER COMO, NIMO, AND NIW/AL2O3 CATALYSTS - KINETICS AND ADSORPTION
No full textRobust saturation controller for linear time-invariant system with structured real parameter uncertainties
No full textThis paper is focused on a robust saturation controller for the linear time-invariant (LTI) system involving both actuator's saturation and structured real parameter uncertainties. The controller suggested in this paper can analytically prescribe the upper and lower bounds of parameter uncertainties, and guarantee the closed-loop robust stability of the system in the presence of actuator's saturation. The suboptimal bang bang control method is extended to LTI system with parameter uncertainties. Based on affine quadratic stability and multi-convexity concept, the robust optimal bang-bang controller is newly derived by minimizing the time derivative of affine Lyapunov function subjected to the limit of control force. Since this controller is a gain-scheduled type, it requires the exact knowledge of uncertain parameters. Another robust saturation controller with a fixed gain is proposed and the linear matrix inequality (LMI)-based sufficient existence conditions for a fixed-gain controller are derived. The effectiveness and the availability of the proposed controller are investigated by a practical numerical example. Through numerical simulations, it is confirmed that the proposed robust saturation controller is robustly stable with respect to parameter uncertainties over the prescribed range defined by the upper and lower bounds. (c) 2005 Elsevier Ltd. All rights reserved
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