Membrane Characterization For Linear And Nonlinear Systems
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Membrane Characterization for Linear and Nonlinear Systems
Gas separation with polymer membranes are becoming one of the mainstream separation techniques for a myriad of industrial applications. Membrane technologies are recognized as a viable and economical unit operation compared to more conventional separation processes. The design and material selection of membrane separation processes depends highly on the transport properties of separated gas molecules within the membrane material. Therefore, to use efficient methods for gas membrane characterization is paramount for the proper design of membrane separation processes. A membrane can be typically characterized by three main properties: permeability, solubility and diffusivity. The permeability of a membrane is the product of its diffusivity and solubility, therefore obtaining two of the three parameters is sufficient to fully characterize a membrane. The time-lag method is one of the oldest and most used gas membrane characterization methods. However, it suffers from various limitations that make the method not applicable for many types of membranes. The focus in this study was to develop new gas membrane characterization techniques that are based on extracting the membrane properties from the upstream gas pressure measurements rather than only from the downstream pressure measurements. It is believed that characterizing the membrane based on the upstream pressure measurements would be highly useful in characterizing barrier materials which are usually difficult to characterize using the conventional time-lag method. Moreover, glassy polymers which are widely used in industry exhibit behavior associated with nonlinear sorption isotherms and, therefore, the conventional time-lag method is incapable of obtaining an accurate estimation of glassy polymer properties. As a result, sorption experiments to generate a sorption isotherm are usually required in addition to permeation experiments to fully characterize glassy polymer membranes. To quantify the errors associated with the conventional time-lag assumptions and to fundamentally comprehend the impact of nonlinearities on the time-lag method, a comprehensive numerical investigation has been undertaken using the finite difference method. The investigation has clearly put in evidence the effect of the various Langmuir parameters on the accuracy of the time lag and on the time required to achieve steady state. This investigation also allowed assessing the errors associated with the usual assumptions made on the boundary conditions in determining the time lag. In this study, three novel gas membrane characterization methods were developed and proposed. Two of the proposed methods are concerned with the characterization of membranes that can be represented with a linear sorption isotherm. These two methods are entirely based on the upstream pressure measurements. The third membrane characterization method that is proposed is based on the dynamic monitoring of both upstream and downstream pressure measurements and is applicable to systems that exhibit a nonlinear isotherm sorption behavior. The three proposed methods are promising and further experimental validation is recommended to determine their full range of applicability.
The Boundary Element Method for Plate Analysis
Boundary Element Method for Plate Analysis offers one of the first systematic and detailed treatments of the application of BEM to plate analysis and design. Aiming to fill in the knowledge gaps left by contributed volumes on the topic and increase the accessibility of the extensive journal literature covering BEM applied to plates, author John T. Katsikadelis draws heavily on his pioneering work in the field to provide a complete introduction to theory and application. Beginning with a chapter of preliminary mathematical background to make the book a self-contained resource, Katsikadelis moves on to cover the application of BEM to basic thin plate problems and more advanced problems. Each chapter contains several examples described in detail and closes with problems to solve. Presenting the BEM as an efficient computational method for practical plate analysis and design, Boundary Element Method for Plate Analysis is a valuable reference for researchers, students and engineers working with BEM and plate challenges within mechanical, civil, aerospace and marine engineering. - One of the first resources dedicated to boundary element analysis of plates, offering a systematic and accessible introductory to theory and application - Authored by a leading figure in the field whose pioneering work has led to the development of BEM as an efficient computational method for practical plate analysis and design - Includes mathematical background, examples and problems in one self-contained resource
The Biophysical Approach to Excitable Systems
Author: William J. Adelman
language: en
Publisher: Springer Science & Business Media
Release Date: 2012-12-06
On July 10, 1980, Kenneth S. Cole became 80 years old. In order to celebrate this landmark, a symposium in the form of a series of Monday evening lectures was held in his honor at the Marine Biological Labora tory throughout the summer of 1980. The selection of speakers was made from among those investigators who had been either his students or co-workers. One intent of the symposium was to examine the current status of knowledge of those areas of interest in excitable membrane structure and function that owe their initiation or encouragement to Kacy Cole. The papers assembled in this volume represent a large majority of the presentations given during the 1980 Cole Symposium. It seems clear on examination of these papers that Kacy's interests in membrane impedance, ion channel conductances, channel fluctuation phenomena, excitation, and the development of membrane biophysical methodology are all being actively pursued. It is also clear that many of his suggestions have borne fruit. Of these, his invention of the voltage v vi Preface clamp method has been most productive. It is hoped that these papers will provide new directions for investigations into the nature of excitable membrane phenomena. The organizers of the symposium and the editors of this volume wish to express their thanks to the Marine Biological Laboratory for making available the facilities for the symposium. They also wish to thank Dr.