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Commercial floating car data (FCD) is being increasingly used as a traffic data source due to its lower cost despite concerns about its reliability. This paper focuses on the evaluation of FCD speed quality as a surrogate measure for arterial speed from different aspects. First, FCD speed is compared to video-based traffic data, collected from a specific urban road segment and assumed as ground truth in (a) descriptive evaluations, (b) speed estimation, and (c) level of service estimation. Regression analysis carried out to derive transformation function between two datasets showed a nonlinear relation with a high correlation coefficient of 0.82. Working with data along an urban corridor of 3.6 km also showed that despite some outliers, FCD was capable of detecting peak-hour queue formations as well as incident related ones. Use of transformation function on FCD speeds helped to increase its potential in urban traffic monitoring. Key words: floating car data (FCD), ground truth (GT), commercial FCD quality, level of service (LOS) estimation, regression analysis. Les donnees de vehicules flottants (DVF) commerciales sont de plus en plus utilisees comme une source de donnees de circulation en raison de leur cout plus faible en depit de preoccupations au sujet de leur fiabilite. Dans le cadre de cet article, on se penche sur l'evaluation de la qualite des DVF sur la vitesse comme mesure de substitution pour la vitesse sur les voies arterielles sous differents aspects. Tout d'abord, les DVF de la vitesse sont comparees aux donnees video sur la circulation, recueillies a partir d'un segment de route urbaine en particulier et presumees etre la realite de terrain, au niveau (a) des evaluations descriptives, (b) de l'estimation de la vitesse et (c) de l'estimation du niveau de service. L'analyse de regression effectuee pour deriver la fonction de transformation entre deux ensembles de donnees a montre une relation non lineaire avec un coefficient de correlation eleve de 0,82. En travaillant avec des donnees obtenues le long d'un couloir urbain de 3,6 km, on a egalement montre que malgre certaines valeurs aberrantes, les DVF etaient capables de detecter les files d'attente aux heures de pointe ainsi que celles liees a un incident. L'utilisation de la fonction de transformation sur les vitesses obtenues des DVF a contribue a accroitre le potentiel des DVF au niveau de la surveillance de la circulation routiere urbaine. Mots-cles : donnees de vehicules flottants (DVF), realite de terrain (RT), qualite des DVF commerciales, estimation du niveau de service, analyse de regression., 1. Introduction Accurate and reliable estimation of traffic speed or state in urban arterials is essential for traffic management and control. Traditional traffic data collection includes various sources (i.e., magnetic [...]

A one-dimensional multiphase numerical model is developed to simulate the vertical settlement involving liquid and gas flows in a deformable (settling) municipal solid waste (MSW) landfill. MSW is represented by a chemical composition, and a global stoichiometric reaction is used to estimate the maximum yield of gas generation. Following the general assumption accepted in the literature, the gas generated by waste decomposition is assumed to comprise of methane (C[H.sub.4]) and carbon dioxide (C[O.sub.2]). The gas generation rate follows an exponentially decaying function of time. The gas generation model developed based on a first-order kinetic single-bioreactor approach includes the governing equations of gas migration, liquid flow, and landfill deformation. The Galerkin finite element method is used to solve the resulting equations. The model developed can be used to estimate the transient and ultimate settlements due to waste decomposition and gas generation in MSW landfills. The proposed model can estimate the waste porosity, gas pressure, liquid pressure, gas saturation, liquid saturation, and stress distributions in settling landfills. The results obtained for a deformable landfill are compared with a landfill having a rigid solid skeleton. Due to settlement, the depth of waste is 27% smaller in deformable landfills than that of the rigid ones. CE Database subject headings: Landfills; Settlement; Solid wastes; Mathematical models; Waste management; Decomposition; Gas.

A theory for one-dimensional self-weight subsidence of saturated soft porous media is presented. The problem is formulated in terms of volume solid fraction using the Eulerian coordinates. Two different types of constitutive relationships between the effective stress and the volume fraction of solids are considered. The governing equations and initial and boundary conditions are nondimensionalized. Self-weight subsidence behavior of unconsolidated soils is analyzed both analytically and numerically. Two sets of exact solutions corresponding to two different compressibility relationships are obtained under steady state conditions. Experimental data available in the literature are used to validate one set of exact solutions. Numerical analysis of transient settlement that allows the movement of the top boundary is presented. The validity of the numerical technique is verified by comparing with exact solutions. The model can be used to predict transient and ultimate settlement and the void ratio distribution of soft soils subsiding under their own weight.

Bioirrigation, in one-dimensional (1D) early diagenetic models, is typically represented by a nonlocal mass transfer or bioirrigation coefficient; alpha that represents all pore water species. Demonstrations reveal that this assumption could possibly lead to significant errors in estimates of bioirrigation intensities.