Capacity Constrained Transit Assignment with Common Lines

This paper proposes the use of absorbing Markov chains to solve the capacity constrained transit network loading problem taking common lines into account. The approach handles congested transit networks, where some passengers will not be able to board because of the absence of sufficient space. The model also handles the common lines problem, where choice of route depends on frequency of arrivals. The mathematical formulation of the problem is presented together with a numerical example. This revised version was published online in July 2006 with corrections to the Cover Date.     

Determination of Hydrogen Single Ion Activity Coefficients in Aqueous HCl Solutions at 25°C

The single ion activity coefficients of hydrogen and chloride ions in aqueous HCl solutions have been estimated at 25°C at concentrations up to 1 mol-kg^–1, using potentiometric measurements with ion-selective electrodes and appropriate calibration procedures. Two methods are described for an internal calibration of the electrodes in the extended Debye–Hückel concentration range. The results are compared to the conventional pH calibration with external buffer solutions. Since the latter calibration method does not account for the liquid junction potential E _J which arises at the reference electrode, the resulting activity coefficients are quite different in HCl solutions of higher concentration. These differences between internal and external calibration decrease significantly, when a correction for E _J is introduced into the conventional pH calibration. Hence, in solutions of higher ionic strength the accuracy of the conventional pH electrode calibration using buffer solutions is very limited, when exact H⁺ activities are required. The consistency of the results indicates that the liquid junction potentials in the examined systems calculated by the Henderson/Bates approximation are of reasonable precision.     

Solubility of sulphur dioxide in aqueous electrolyte solutions at higher ionic strengths—Chloride and bromide containing systems

The absorption of sulphur dioxide in chloride and bromide containing electrolyte solutions was measured up to ionic strengths of 5 mol/dm³. The thermodynamic equilibrium of the gas phase and the liquid phase was characterized by UV spectroscopy. UV spectra analysis gave strong evidence for SO₂X⁻ complexes existing in the solutions. Consequently, these compounds were implemented in the reaction scheme for absorption.     

DTA,ETA, and TG investigations of Zirconium phosphates of different crystallinity

Interpretation of all thermal effects which occur on heating zirconium phosphates is possible when simultaneous DTA, ETA, and TG is applied. A rapid transition of poorly crystalline zirconium phosphate into normal cubic modification at high temperatures is clearly shown by DTA when amorphous zirconium phosphate is used. In contrast, because of the more rigid crystal lattice, this reaction is only visible in ETA when crystalline preparations are heated.Especially after exchange of protons by cations, some amorphous zirconium phosphates exhibit a second exotherm in DTA. This reaction is believed to depend on growing up of partially crystalline structures.