Model-based control of a simulated moving bed chromatographic process for the separation of fructose and glucose

Chromatographic separations are an expanding technology for the separation of high value products, particularly in the area of pharmaceutics, food, and fine chemicals. The simulated moving bed (SMB) process as a continuous chromatographic separation process is an interesting alternative to conventional batch chromatography, and gained more and more impact recently. The SMB process is realized by connecting several single chromatographic columns in series. A countercurrent movement of the bed is approximated by a cyclic switching of the inlet and outlet ports in the direction of the fluid stream. Because of its complex dynamics, the optimal operation and automatic control of SMB processes is a challenging task. This paper presents the design of a model-based optimization and control scheme for SMB chromatographic separation processes and its application to the separation of fructose and glucose. We propose a two-layer control architecture where the optimal operating trajectory is calculated off-line by dynamic optimization based on a rigorous process model. The parameters of the model are adapted based on online measurements. The low-level control task is to keep the process on the optimal trajectory despite disturbances and plant/model mismatch. Here identification models based on simulation data of the rigorous process model along the optimal trajectory are combined with a suitable local controller. The efficiency of the trajectory control algorithm is shown in a simulation study for the separation of fructose and glucose on an 8-column SMB plant.     

An Architecture for Supporting Multi-Device, Client-Adaptive Services

The original idea of the World Wide Web was to create a universe of network-accessible information. Since its inception, the World Wide Web has evolved from a means to help people access and use information into an interactive medium. This has caused a dramatic increase in the development effort for interactive services, which now have to support multiple clients with widely varying computing and user interface capabilities. Personalization features tend to render this task even more complex. The paper presents the MUSA (Multiple User Interfaces, Single Application) system, which addresses both issues with the introduction of an event graph that abstracts user interface and personalization issues from the implementation of the service on different client-devices.     

Revealing of major factors in the directional thermal radiation of ground objects——A new way for improving the precision of directional radiant temperature measuring and data analysis

This paper is devoted to eliminating the noise from the measuring of directional thermal radiation for ground objects. Specifically, we think that the noise is mainly due to the variance of components in the field of view of the sensor with the view angle changing and to the heat balance change on the ground during the period of measurement. The authors present two new observation methods named as "constant area method by thermal camera" and "concurrent method by dual sensors" respectively. The experiments show that the data obtained by these methods abide by some regularly directional distribution, which is totally different from the data from the former methods. The analysis of the major factors in the directionality of thermal radiation is also made in the paper.     

An on-line respirographic biosensor for the characterization of load and toxicity of wastewaters

A respirographic biosensor is presented that is capable of monitoring the waste load and potential toxicity of wastewaters, both off-line in a laboratory or on-line at the wastewater treatment plant. The principles of the sensors' operation have been developed and implications of the design choices evaluated. Short term BOD values were obtained every 30 min. The linear dynamic range spanned concentrations differing by a factor of 5000. This range could be expanded by a factor of 10 by adjusting the aeration rate of the bioreactor in the sensor. The response time for toxicity detection was approximately 1 h. The use in the sensor of activated sludge from the plant concerned ensured relevant toxicity information was obtained. To check the condition of the sludge, an independent respiration measurement is proposed. When a siginificant activity change is observed, the sludge in the sensor must be replaced. The presence of oxidoreduction chemicals can cause interferences that may lead to measurement errors. Based on a difference in reaction kinetics, their presence can be assessed and the effect eliminated. Both on-line and laboratory applications in the chemical industry are presented. Special emphasis is given to the usefulness of the sensor data for waste management of production divisions. On-line assessment of load variations and hydrogen peroxide spills are given as illustrations of the implementation of the sensor on the treatment plant. Attention is drawn to the potential application of the data for process control and improved performance of the treatment plant.     

The Affinity of Basic Dyes for Leacril 16 Acrylic Fibre

The dyeing affinity of some thiazole and benzothiazole basic azo dyes for Leacril 16 acrylic fibre was measured using Langmuir isotherms. Results show a close dependence of dye structure on affinity.     

Die prozentuale Zusammensetzung der freien Fettsäuren im Vergleich zum Fettsäuremuster nach Verseifung (Gesamtfettsäuren) bei einigen frischen und gelagerten tierischen Lebensmitteln

Percent Composition of Free Fatty Acids of a Few Fresh and Stored Animal Food Products in Comparison to Their Fatty Acid Pattern after Saponification Depot fat and muscle fat of fresh and stored chickens as well as beef tallow and milk fat were analysed after saponification by gas-liquid chromatography as their methyl esters. The free fatty acids of the same fats were absorbed on alumina and examined for their composition after desorption in the same way. The amount of free fatty acids after lipolysis was not identical with the percentage of fatty acids of the fats. Palmitoleic-, oleic-, and linoleic acid showed an increase, but palmitic and stearic acid a decrease of their amounts in the liberated acids in comparison to the composition of the fatty acids of neutral fats. A remarkable amount of volatile acids could be detected in the free fatty acids only.