4,117 research outputs found
Reactive extraction of lactic acid with tricctylamine/methylene chloride/n-hexane
No full textThe trioctylamine (TOA)/methylene chloride (MC)/n-hexane system was used as the extraction agent for the extraction of lactic acid. Curves of equilibrium and hydration were obtained at various temperatures and concentrations of TOA. A modified mass action model was proposed to interpret the equilibrium and the hydration curves. The reaction mechanism and the corresponding parameters which best represent the equilibrium data were estimated, and the concentration of water in the organic phase was predicted by inserting the parameters into the simple mathematical equation of the modified model. The concentration of MC and the change of temperature were important factors for the extraction and the stripping process. The stripping was performed by a simple distillation which was a combination of temperature-swing regeneration and diluent-swing regeneration. The type of inactive diluent has no influence on the stripping. The stripping efficiencies were about 70%
Water-enhanced solubilities of lactic acid in reactive extraction using trioctylamine various active diluents systems
No full textTrioctylamine (TOA) was used as the extraction agent for reactive extraction in various active diluents. Equilibrium and hydration data for various active diluents were obtained in 0.6 M TOA systems. From these data we divided the active diluents used into three classes: active diluents containing chlorine atoms, carbon-bonded oxygen donor active diluents, and phosphorus-bonded oxygen donor active diluents. This classification was based on the characteristic groups of active diluents. The amounts of lactic acid and water in the organic phase were strongly affected by physical extraction of the active diluents. The relationships between coextracted water and lactic acid extracted were represented by slopes in drawings. The sensitivity index, which is defined as the inverse of a slope, was introduced as the measure of the water-enhanced solubilities of lactic acid. Factors affecting the reactive extraction of lactic acid and water, such as the type of active diluents, the moles of amine used, and the bulkiness of the active diluents, were explained based on the characteristic groups of the active diluents
Vibration control of structures with interferometric sensor non-linearity
No full textExperimental studies on vibration control of a composite beam with a piezoelectric actuator and an extrinsic Fabry-Perot interferometer (EFPI) have been performed using a neural network controller. Because of their interferometric characteristics, EFPI sensors show non-linearity as dynamic amplitude increases. Within the linear range of EFPI, conventional control algorithms can be applied without serious difficulty. However, closed-loop control may make the target system unstable when sensor non-linearity gets high. Therefore, we examine the effects of the non-linearity of the sensor on the control stability and performance, and investigate any simple method applicable to the vibrations beyond the linear range. For this purpose, a neural controller is adopted and its performance is experimentally investigated. The neuro-controller showed good performance and adaptiveness to the sensor's non-linearity. Although the present neuro-controller is not a fundamental solution to vibration control of structural systems, it can be a simple practical choice for systems with sensor non-linearity.The present study has been supported by a grant from the National Research Laboratory
Program of the Ministry of Science and Technology, Korea. The authors gratefully
acknowledge this support (Subject No. 2000-N-NL-01-C-250)
Application of fiber optic sensor and piezoelectric actuator to flutter suppression
No full textThe present study has been supported by a grant from the National Research Laboratory
Program of the Ministry of Science and Technology, Korea. The authors gratefully
acknowledge this support (Subject No. 2000-N-NL-01-C-250)
STUDY ON THE POSSIBLE EXISTENCE OF MULTIPLICITY FEATURES IN ETHENE HYDROGENATION OVER PLATINUM BOEHMITE CATALYSTS
No full textThe possible existence of multiplicity features, including ignition and extinction phenomena, are examined in ethene hydrogenation over a very short fixed bed of platinum/boehmite catalysts. Ethene hydrogenation is compared with carbon monoxide oxidation for which it has been claimed in several studies that multiple steady states can occur within the kinetic region. In our experiments an important experimental parameters is the size of the catalyst charge in the reactor. In ethene hydrogenation the multiplicity feature cannot be observed below a certain size of catalyst charge. On the other hand, in carbon monoxide oxidation this multiplicity can be observed regardless of catalyst charge size. From our observations, it is concluded that the multiplicity in ethene hydrogenation cannot be attributed to a purely kinetic process, but it results from the interaction of the chemical reaction and the heat transfer process
Experimental study on the effects of visualized functionally abstracted information on process control tasks
No full textTwo distinct design problems of information display for process control are information content representation and visual form design. Regarding information content, we experimentally showed the effectiveness of functionally abstracted information without the benefits of sophisticated graphical presentation in various task situations. However, since it is obvious that the effects of the information display are also influenced by display formats (i.e., visual forms) as well as the information content, further research was required to investigate the effectiveness of visualized functionally abstracted information. For this purpose, this study conducted an experiment in complex process control tasks (operation and fault diagnosis). The experimental purposes were to confirm the effectiveness of the functionally abstracted information visualized with emergent features or peculiar geometric forms and to examine the additional effects of the visualization on task performance. The results showed that functionally abstracted information presented with sophisticated visual forms helped operators perform process control tasks in more efficient and safe way. The results also indicated the importance of explicit visualization of goal-means relation between higher and lower abstraction levels. Lastly, this study proposed a framework for designing visual forms for process control display. (c) 2007 Elsevier Ltd. All rights reserved
Direct recovery of intracellular proteins from Candida utilis using reverse micelles in combination with reducing agent
No full textIntracellular proteins were directly extracted from Candida utilis using reverse micelles in combination with a reducing agent. Extraction at pH 10 using 80 mM cetyl trimethyl ammonium bromide (CTAB) and 0.2 % 2-mercaptoethanol was the most favorable condition for cell permeabilization and protein solubilization. Stripping at pH 7 in the presence of 0.5 M KCl resulted in the efficient recovery of solubilized proteins
Assessment of a DNB-type theoretical critical heat flux model for rod bundles with non-uniform axial power shapes
No full textA general critical heat flux (CHF) prediction method with a wide applicable range and reasonable accuracy is essential to the thermal-hydraulic design and safety analysis at the conceptual design stage for a new pressurized water reactor (PWR). In this study, the Korea Advanced Institute of Science and Technology (KAIST) liquid sub-layer dryout CHF prediction model for Departure from Nucleate Boiling (DNB) region has been implemented in a sub-channel analysis code. and investigated for the method's possible use in a rod bundle environment with various non-uniform axial power shapes. The KAIST model showed comparable prediction capability to Lin's method for bottom-. center-. and top-peaked heat flux shapes. The KAIST model. without any correction factors or empirical constants, turned out to be suitable to fulfill the needs for a basis of a general CHF prediction method as compared to Lin's method and Westinghouse-3 (W-3) correlation. (C) 2005 Published by Elsevier B.V
Water enhanced solubilities of succinic acid in reactive extraction using tertiary amines/alcohols systems
No full textTertiary amines were used as the extractants for reactive extraction in alcohol diluents. Equilibrium and hydration data for various alcohol diluents and tertiary amines were obtained. From these data, the effect of coextracted water on extractability was investigated. For the measurement of the water-enhanced solubilities of succinic acid, the sensitivity index was introduced. The amount of coextracted water into organic phase was increased with the chain length of alcohol diluents. However, the water-enhanced solubility of succinic acid was almost constant with the chain length of alcohol diluents. The sensitivity indices were proportional to the chain length of tertiary amines; thus, the water-enhanced solubilities of succinic acid were increased
Separation characteristics of lactic acid in reactive extraction and stripping
No full textLactic acid has recently been drawing much interest as a raw material for biodegradable polymer. Various extractants for lactic acid separation were tested and TOA (trioctylamine) was found the most effective one. Lactic acid was separated by reactive extraction with TOA dissolved in various diluents. The effect of temperature on the extraction efficiency was smaller than that of composition for the system studied in this work
- …
