Determination of Fibre Pore Structure: Influence of Salt,pH and Conventional Wet Strength Resins

It has been shown, in the present investigation, that the two methods used to investigate the pore size distribution of unbleached chemical pulps, i.e. inverse size exclusion chromatography (ISEC) and nuclear magnetic resonance (NMR), give different average pore radius for the pores inside the fibre wall. This is due to the way in which these experiments are performed and the sensitivity of the methods to different types of pores in the cell wall. It was also shown that the two methods gave different results when changing the pH and the ionic strength of the pulp suspension. The pore radius, as detected with ISEC, decreased with both increasing ionic strength and decreasing pH, indicating a loose structure of the exterior of the fibrillar network. However, the pore radius as detected with NMR, was virtually unaffected when increasing the ionic strength, indicating a very rigid structure of the interior of the fibre wall. Decreasing pH though, lead to a decrease in pore radius indicating that upon protonation of the carboxylic groups in the fibre wall, the electrostatic repulsion is diminished and the average pore radius decreases. The NMR technique was also used to study wet strength aid penetration into the fibre wall. It was shown that wet strength aids with a small molecular weight, penetrated the fibre wall, as detected by a decrease in pore radius. It was also shown that addition of different wet strength aids increased the tensile index of the sheet and decreased the fibre strength, measured as zero span-strength of the sheets.     

Quantifying the Effectiveness of Patterning,Test Conditions,and DIC Parameters for Characterization of Plastic Strain Localization

Experimental Mechanics - Digital image correlation, commonly referred to as DIC, enables full-field measurements of displacements and strains from a surface of interest. While DIC offers major...     

An Analysis of the Induced Linear Operators Associated to Divide and Color Models

Journal of Theoretical Probability - We study the natural linear operators associated to divide and color (DC) models. The degree of nonuniqueness of the random partition yielding a DC model is...     

Denseness of volatile and nonvolatile sequences of functions

In a recent paper by Jonasson and Steif, definitions to describe the volatility of sequences of Boolean functions, $f_n:{\{?1,1\}}^n\to \{?1,1\}$ were introduced. We continue their study of how these definitions relate to noise stability and noise sensitivity. Our main results are that the set of volatile sequences of Boolean functions is a natural way “dense” in the set of all sequences of Boolean functions, and that the set of non-volatile Boolean sequences is not “dense” in the set of noise stable sequences of Boolean functions.     

Optimization of operating strategies in a community solar heating system

Minimization of auxiliary energy costs is discussed for heating in a district solar heating system with effective heat storage. The minimization problem is approached by dynamic programming which gives an optimal operating strategy for the auxiliary energy system. The effects of different pricing schemes of auxiliary energy (electricity) have been studied. The results show that with an adequate heat storage capacity, the optimization of the auxiliary energy use in a community solar heating system may lead to considerable cost savings.     

The Spectrum and Convergence Rates of Exclusion and Interchange Processes on the Complete Graph

We give a short and completely elementary method to find the full spectrum of the exclusion process and a nicely limited superset of the spectrum of the interchange process (a.k.a. random transpositions) on the complete graph. In the case of the exclusion process, this gives a simple closed-form expression for all the eigenvalues and their multiplicities. This result is then used to give an exact expression for the distance in \( L^2 \) from stationarity at any time and upper and lower bounds on the convergence rate for the exclusion process. In the case of the interchange process, upper and lower bounds are similarly found. Our results strengthen or reprove many known results about the mixing time for the two processes in a very simple way.