Experimental investigations on the initiation of external suffusion

Piping -- Concentrated leak erosion -- Backward erosion -- Suffusion -- Theoretical description -- Objectives -- Experimental design -- Procedure of the experiments -- Measurements -- Experiment type -- Results and discussions

Slope Stability Analyses of Waste Rock Piles Under Unsaturated Conditions Following Large Precipitations

RÉSUMÉ Les roches stériles sont extraites des mines pour accéder aux zones minéralisées. Le traitement de cette roche n’est pas économiquement rentable. Les roches stériles sont habituellement transportées par camions (ou convoyeurs) et disposées en haldes à la surface. Ces haldes doivent être conçues de manière à assurer leur stabilité géotechnique pendant que la mine est en opération et après sa fermeture. La construction optimale de ces haldes à stériles requiert une bonne planification. La présente thèse traite de l’analyse de la stabilité des haldes de grande taille. Les principaux objectifs du travail présenté dans cette thèse consistent à i) enrichir les connaissances sur le comportement géotechnique des haldes à stériles de grande taille, ii) étudier l’effet des propriétés mécaniques des matériaux sur la stabilités des haldes, iii) améliorer la capacité d’évaluer la stabilité de la pente des haldes selon différentes configurations internes et externes, iv) étudier les effets de l’infiltration d’eau et des fluctuations des pressions interstitielles négatives (succion matricielle) sur la stabilité des pentes des haldes à stériles en conditions non saturées sur le facteur de sécurité, et v) étudier l’influence de la variabilité spatiale des propriétés mécaniques des matériaux dans les haldes sur leur stabilité. Même si elles se basent sur des situations typiques, les analyses n’ont pas été menées pour simuler en détail un cas spécifique, mais plutôt pour mettre en application une procédure d’évaluation systématique de la stabilité des haldes à stériles non saturées, en tenant compte des paramètres qui l’influencent ----------ABSTRACT Waste rock is extracted from mines to reach the ore zones and is not economically valuable. They are usually transported by truck (or conveyor) and placed in waste rock piles on the ground surface. Waste rock piles must be designed to ensure their geotechnical stability during mine operations and after closure. The optimal construction of a pile requires detailed planning. This thesis deals with the stability analysis of large waste rock piles. The main objectives of the work presented in this thesis were to i) increase the knowledge of the geotechnical behaviour of large waste rock piles, ii) investigate the effect of material properties on waste rock pile stability, iii) improve the ability to estimate the slope stability of waste rock piles of different internal and external configurations, iv) investigate the contribution of water infiltration and change in the matric suction (negative pore water pressure) on the slope stability of unsaturated waste rock piles and the related changes in the factors of safety, and v) study the influence of spatial variability of the waste rock mechanical properties on stability. This study used numerical analysis to assess the behaviour and stability of unsaturated waste rock piles. Although based on typical situations, these analyses were not intended to simulate particular cases in detail, but rather to apply a systematic procedure to evaluate the stability of unsaturated waste rock piles and investigate the influencing parameters

Evaluation of In vitro Antioxidant and In vivo Antihyperlipidemic Activities of Methanol Extract of Aerial Part of Crassocephalum crepidioides (Asteraceae) Benth S Moore

Purpose: To evaluate the antioxidant and antihyperlipidemic activities of the methanol extract of aerial part of Crassocephalum crepidioides (Asteraceae) Benth. S. Moore.Methods: The methanol extract of Crassocephalum crepidioides was prepared by organic solvent extraction (Maceration) and assessed for in vitro antioxidant activity using various methods, namely, 2,2 diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay, total phenol and flavonoid content and reducing capacity. The extract was also evaluated for antihyperlipidemic activity in high-fat diet and triton WR-100 (iso-octyl polyoxyethylene phenol)-induced hyperlipidemic albino rats by evaluating serum total cholesterol (TC), high-density lipoprotein cholesterol (HDL-c), triglycerides (TG), very low density lipoprotein cholesterol (VLDL-c), low-density lipoprotein cholesterol (LDL-c) level and atherogenic index (AI).Results: The plant extract showed significant antioxidant activity in a dose-dependent manner. In highfat diet hyperlipedemic rats, the extract significantly reduced (p < 0.01 or 0.001) serum TC, TG, LDL-c and VLDL-c levels, but significantly increased (p < 0.05) serum HDL c level. In triton-induced hyperlipidemic rats, the extract significantly reduced (p < 0.05, p < 0.01, p < 0.001) serum TC, TG, LDLc, VLDL-c levels but significantly increased (p < 0.05) serum HDL-c level. The extract showed significant reduction (p < 0.01) in AI at 300 mg /kg/day dose in both high fat-induced (1.70 ± 0.25) and tritoninduced (1.5 ± 0.17) hyperlipidemic albino rats.Conclusion: Based on these findings, the extract of Crassocephalum crepidioides aids in lowering hyperlipidemia in rats. This is probably due to its antioxidant activity.Keywords: Antioxidant, Antihyperlipidemic, Crassocephalum crepidioides, Triton WR-100, Atherogenic inde

Scheduling Material Handling in Cross-Docking Terminals

RÉSUMÉ : La manutention au sein des plateformes de distribution est un problème d’ordonnancement. Le transport interne des produits doit en effet être synchronisé avec les arrivées et les départs des camions. Ce problème se retrouve dans toutes les plateformes de distribution où la manipulation des produits est effectuée manuellement par l’opérateur. Dans cette thèse, nous investiguons ce problème d’ordonnancement dans les plateformes de distribution. Nous mettons en relief les différentes facettes de ce problème et proposons une classification de ses différents sous problèmes. De manière générale, l'objectif est d'éviter les doubles manipulations (déplacer un produit d’un camion vers le stock, puis du stock vers un camion) qui doublent les coûts sans valeur ajoutée. Il faut minimiser ces doubles manipulations en orchestrant les transferts internes et la séquence de chargement/ déchargement des camions. Dans une première partie, nous analysons la structure du problème avec un modèle simplifié n’ayant qu’un quai de réception et un quai d’envois. Nous formalisons les décisions de manipulation interne et développons un algorithme optimal pour déterminer le meilleur plan de transfert de produits lorsque la séquence des camions est connue. Cet algorithme est utilisé comme fonction d’évaluation dans une recherche stochastique pour minimiser les doubles manipulations et optimisant les séquences de chargement/déchargement. Nous présentons ensuite un modèle de programmation linéaire en nombres entiers du problème général (ordonnancement des arrivées et départs de camions et transfert interne des produits). Nous proposons un algorithme de séparation et d’évaluation permettant une résolution efficace du problème. Nous proposons des structures de dominance et quelques inégalités valides permettant d’améliorer les performances de l’algorithme. Cette approche nous permet de résoudre à l’optimum en un temps raisonnable de très gros problèmes. Dans une seconde partie, nous étendons ces modèles au problème général avec plusieurs quais. Nous nous intéressons d’abord au terminal de type satellite où l’ordonnancement des camions d’entrée est connu. Ces plateformes opèrent en deux mouvements différents : l’ordonnancement et chargement pour le transport de nuit et celui pour les livraisons matinales. Nous donnons une représentation mathématique qui permet de résoudre les problèmes de petite taille. Pour ceux de plus grandes ampleurs, nous utilisons une heuristique. Les résultats numériques montrent la validité de cette approche. Finalement, nous généralisons le type de plateforme (les séquences d’arrivée et de départ sont à déterminer) et développons un nouveau modèle d’ordonnancement plus compact. Nous utilisons pour les grandes instances une recherche par voisinage. Nous mettons en place des voisinages originaux adaptés à ce type d’ordonnancement. Mots clés: Transfert de produits, ordonnancement, plateforme de transbordement, recherche stochastique, programmation à nombres entiers, heuristiques, recherche du plus proche voisin.----------ABSTRACT : Material handling in cross-dock is a relevant class of scheduling problems in distribution centers in which inner transhipment decisions need to be considered in addition to the processing order of trucks. The problem has applications in distribution centers where operators manually perform internal transhipment. In this dissertation, we investigate the problem of material handling inside cross-docking terminals. The main component of the problem is presented, followed by a classification scheme to express its diversity. Moreover, double handling identifies the main source of deficiencies in transferring operations. The objective is to synchronize the trucks’ loading and unloading sequences with internal transferring decisions to minimize excessive product displacement inside the terminal. First, the problem is studied for a conceptual model of the platform with single receiving and shipping doors. We formalize decisions on internal transhipment and develop an algorithm to determine the best transferring plan with restricted orders on processing trucks. This algorithm is employed as an evaluation function in a stochastic search framework to ameliorate the order of processing trucks and reduce the cost of double handling. Then, a mixed integer linear programming formulation of the general problem is introduced. The proposed model determines the joint schedule between processing order of trucks at inbound and outbound doors with an internal transhipment plan. A path branching algorithm is proposed. We present several structural properties and some valid inequalities to enhance the performance of the algorithm. This method could solve fairly large instances within a reasonable time. Second, we extend the developed models and approaches to schedule material handling process for a real platform with multiple doors. In the first installment, we focus on the satellite cross-docks that have limitations on the processing order of trucks at inbound door. These platforms operate in two separate shifts: consolidating pickup freight for overnight shipments and processing received products for early morning deliveries. A mathematical formulation of the problem is presented that can solve small instances with commercial software. In addition, a sequential priority-based heuristic is introduced to tackle the large problems. Numerical results depict the stability of this approach. Finally, in the second instalment, we study the general model with no restriction on the arrival and departure pattern of trucks and formulate a new mathematical model. This model has considerably fewer variables and constraints than the previous one. Moreover, a variable neighborhood search heuristic is developed to tackle real life problems. This method consists of several operators incorporated in a search subroutine to find local optima and a perturbation operator to alter it. The developed method is adopted for three scenarios concerning limitations imposed by the network schedule. The analyzes demonstrate economical savings in the cost of material handling. Keywords: Material handling; scheduling; cross-dock; stochastic search; Integer programming; heuristic; variable neighborhood search

Railway Passenger Service Timetable Design

The aim of this paper is to analyze and to improve the current planning process of the passenger railway service. At first, the state-of-the-art in research is presented. Given the recent changes in legislature allowing competitors to enter the railway industry in Europe, also known as liberalization of railways, the current way of planning does not reflect the situation anymore. The original planning is based on the accessibility/mobility concept provided by one carrier, whereas the competitive market consists of several carriers that are driven by the profit. Moreover, the current practice does not define the ideal timetables (the initial most profitable timetables) and thus it is assumed that the Train Operating Companies (TOCs) use their historical data (train occupation, ticket sales, etc.) in order to construct the ideal timetables. For the first time in this field, we tackle the problem of ideal timetables in railway industry from the both points of view: TOCs’ and passengers’. We propose the Ideal Train Timetabling Problem (ITTP) to create a list of train timetables for each TOC separately. The ITTP approach incorporates the passenger demand in the planning and its aim is to maximize TOCs’ profits while keeping the passengers’ costs at a certain level. The outcome of the ITTP is the ideal timetables (including connections between the trains), which then serve as inputs for the traditional Train Timetabling Problem (TTP). We test our approach on the S-train network of Canton Vaud, Switzerland

The multi-objective railway timetable rescheduling problem

Unexpected disruptions occur for many reasons in railway networks and cause delays, cancelations, and, eventually, passenger inconvenience. This research focuses on the railway timetable rescheduling problem from a macroscopic point of view in case of large disruptions. The originality of our approach is to integrate three objectives to generate a disposition timetable: the passenger satisfaction, the operational costs and the deviation. from the undisrupted timetable. We formulate the problem as an Integer Linear Program that optimizes the first objective and includes epsilon-constraints for the two other ones. By solving the problem for different values of epsilon, the three-dimensional Pareto frontier can be explored to understand the trade-offs among the three objectives. The model includes measures such as canceling, delaying or rerouting the trains of the undisrupted timetable, as well as scheduling emergency trains. Furthermore, passenger flows are adapted dynamically to the new timetable. Computational experiments are performed on a realistic case study based on a heavily used part of the Dutch railway network. The model is able to find optimal solutions in reasonable computational times. The results provide evidence that adopting a demand-oriented approach for the management of disruptions not only is possible, but may lead to significant improvement in passenger satisfaction, associated with a low operational cost of the disposition timetable. (C) 2017 Elsevier Ltd. All rights reserved

Effects of copper in Daphnia are modulated by nanosized titanium dioxide and natural organic matter: what is the impact of aging duration?

During its aquatic life cycle, nanosized titanium dioxide (nTiO(2)) may interact with natural organic matter (NOM) ultimately altering the ecotoxicity of co-occurring chemical stressors such as heavy metals (e.g. copper (Cu)). In this context, the following hypotheses were tested: (1) aging of nTiO(2) along with Cu reduces Cu toxicity, (2) nTiO(2) agglomerates have a lower potential to reduce Cu toxicity and (3) aging of nTiO(2) in presence of NOM reduces Cu toxicity further. A multifactorial test design crossing three nTiO(2) levels (0.0, 0.6 and 3.0 mg/L) with two levels of NOM (0 versus 8 mg total organic carbon (TOC)/L) and seven nominal Cu concentrations (ranging from 0 to 1536 mu g/L) aged in ASTM medium for 0, 1, 3 and 6 days was realised, while two aging scenarios were applied (type 1: nTiO(2) jointly aged with Cu; type 2: Cu added after nTiO(2) aging). Subsequently, Cu toxicity was assessed using the immobility of Daphnia magna after 48 h of exposure as response variable. The experiments revealed that neither aging duration nor the extent of agglomeration (type 1 vs. type 2 aging) has a substantial impact on Cu induced toxicity. Moreover, it was confirmed that the presence of NOM substantially reduced Cu induced toxicity, independent of the aging scenario and duration. More importantly, the data suggest the ingestion of Cu loaded nTiO(2) as additional exposure pathway contributing to Cu toxicity. In conclusion, it seems unlikely that nTiO(2) concentrations currently detected in or predicted for aquatic ecosystems, which are at least one order of magnitude below the concentration tested here, influence Cu toxicity meaningfully

Multiple attribute decision making (MADM) based scenarios

Decision making takes into account a myriad of factors about the future topics, which often prove challenging and quite complicated. Multiple Attribute Decision-Making (MADM) methods still have not become powerful enough to help decision makers to adopt the best solutions regarding future issues. Different scenarios are suitable for developing an appropriate outlook toward different probable futures. Scenarios are not inherently quantitative, but recently different integrated quantitative methods have been incorporated with the processes in various studies. Previously, different types of scenario-based MADM methods have been presented in different studies, but they just considered each case separately. In those studies, MADM methods were only applied to evaluate the situation in scenario-based MADM. This research concentrates on another paradigm in applying scenarios to upcoming events, MADM methods in the new area are explored, and the concept, which is called MADM based scenarios, is presented. In different situations and scenarios, different MADM models will happen. New concepts about most useful criterion and applicable alternatives are introduced in this new approach for decision-making about the future. In addition, a general framework is proposed for applying MADM-based scenarios for unpredictable scenarios and situations, which can be almost controlled future in practice