REVITILIZING THE ONTARIO PUBLIC EDUCATION SYSTEM FOR YOUNG ENGLISH LANGUAGE LEARNERS

Herein we argue that teachers who work to foster their ability to teach English language learners effectively need to learn about their students. Although Ontario (Canada) educators have demonstrated that English language learners’ cultural knowledge and language abilities can be mobilized within the classroom as important tools and resources for learning the systematic development of language policy at the school level is crucial for extending innovative practices and attitudes into schools across the province.  Such policy should reflect the demographic trends and recent research literature that recommends teachers must be informed and able to assess and evaluate English proficiency since this can disguise and hinder students from communicating the information they know.  Teachers, therefore, must be diligent and perceptive to accurately measure and record information that the student does know. Given this stance we present a review of the perspectives and attitudes of Ontario Elementary school teachers towards skills, abilities, and training for teaching young English language learners.  We introduce current themes and facts prevalent in the OMOE literature pertaining to effective ELL education and professional development for teachers to implement and foster English acquisition and student success

Minimisation du Content par une méthode d'active set pour les équations d'équilibrage hydraulique conduites par la pression

International audienceA new content-based, box-constrained, active-set projected Newton method is presented that solves for the heads, the pipe flows, and the nodal outflows of a water distribution system in which nodal outflows are pressure dependent. The new method is attractive because, by comparison with the previously published weighted least-squares energy and mass residuals (EMR) damped Newton method, (1) it typically takes fewer iterations, (2) it does not require damping, (3) it takes less wall-clock time, (4) it does not require the addition of any virtual elements, and (5) it is algorithmically easier to deal with. Various pressure-outflow relationships (PORs), which model nodal outflows, were considered and two new PORs are presented. The new method is shown, by application to eight previously published case study networks with up to about 20,000 pipes and 18,000 nodes, to be up to five times faster than the EMR method and to take between 34% and 70% fewer iterations than the EMR method

Zur hydraulischen Systemanalyse von Wasserversorgungsnetzen [online]

Kurzfassung Städtische Wasserversorgungssysteme stellen einen komplexen Bestandteil der technischen Infrastruktur dar. In den vergangenen Jahrzehnten fand, bedingt durch die Verbreitung immer leistungsfähigerer Rechenanlagen, eine rasante Entwicklung unterschiedlicher mathematischer Modelle auf dem Gebiet der Systemanalyse städtischer Druckrohrnetze statt. Die Haupteinsatzbereiche können grob in Entwurf kostenoptimaler Netze bei Neuplanung und Erweiterung, Simulation des täglichen Betriebs und Kalibrierung der mathematischen Abbildung eingeteilt werden. Dabei lassen sich keine klaren Abgrenzungen vornehmen, besonders Methoden der beiden zuletzt genannten gehen teilweise nahtlos ineinander über. Im Rahmen dieser Arbeit steht die Simulation des stationären Fließzustandes im Mittelpunkt der Betrachtung. Beschleunigungseffekte sind wegen der geringen Fließgeschwindigkeit in städtischen Wasserversorgungssystemen zu vernachlässigen, \u27dynamische\u27 Berechnungen (Simulation des zeitabhängigen Betriebs) finden als Sequenz einzelner stationärer Simulationsrechnungen statt. Reale Wasserversorgungsnetze beinhalten eine Vielzahl unterschiedlicher Armaturen, die der Kontrolle und Steuerung dienen. Ihr Einsatz reicht von Rehabilitation defekter Netzteile über den energiesparenden Betrieb der Anlagen und Minimierung von Leckageverlusten bis zur optimierten Datenerhebung in Messkampagnen zur Mängelidentifikation und Kalibrierung. Mit Bezug auf die Durchführung stationärer Simulationsrechnungen lässt sich das hydraulische Verhalten der Anlagen drei Gruppen zuordnen: i) Hydraulisches Verhalten und Betriebszustand vor Simulation bekannt, ii) hydraulisches Verhalten bekannt, Betriebszustand vor Simulation unbekannt, iii) Betriebszustand und hydraulisches Verhalten vor Simulation unbekannt (Anlagen mit Rückkoppelung). Es werden, zunächst ohne Berücksichtigung der oben genannten Kontrollarmaturen, die zur Beschreibung des stationären Fließzustandes notwendigen Gleichgewichtsbedingungen angegeben (synthetische Methode). Danach wird eine alternative Vorgehensweise, deren Ziel die Herleitung eines äquivalenten mathematischen Modells, das zweckmäßig die Form einer Optimierungsaufgabe besitzt, besprochen (analytische Methode). Der Vorteil der zweiten Variante liegt in der Möglichkeit, Existenz- und Eindeutigkeitsaussagen treffen zu können, des Weiteren sind Sensitivitätssätze und Algorithmen aus der Optimierung auf das Problem anwendbar. Das entwickelte Modell besitzt die Gestalt einer konvexen, nichtlinearen Minimierungsaufgabe ohne Nebenbedingungen (Minimierung des System-\u27Content\u27). Es gibt den Stand der mathematischen Entwicklungen auf dem Gebiet der analytischen Methoden in der stationären Flussberechnung von vermaschten Druckrohrnetzen wieder und gestattet die Berücksichtigung von Behältern, Drosselklappen und Pumpen mit gegebener Formulierung des hydraulischen Verhaltens. Im nächsten Schritt werden Kontrollarmaturen nach Punkt i) und ii) eingeführt. Als Konsequenz kommen lineare Gleichungs- und Ungleichungsnebenbedingungen hinzu. Die mathematische Umgebung des Aufgabengebietes werden definiert und allgemeine Bedingungen an die hydraulischen Beziehungen der Systemelemente formuliert, welche hinreichend für die Konvexität der Aufgabe sind. Diese Erweiterung des mathematischen Modells gestattet die Berücksichtigung von Durchflusskontrollschiebern, Rückflussverhinderungsventilen, zeitweise geschlossenen Schiebern, aber auch die realistische Simulation unterschiedlicher Systemmängel wie druckabhängige Leckagen und unzureichende Versorgung. Die Anwendung von Sensitivitätssätzen der Nichtlinearen Programmierung liefert Aussagen über die Änderung der Systemvariablen infolge von Parameteränderungen. In realen Versorgungssystemen finden zusätzlich Armaturen nach Typ iii) Anwendung, deren hydraulisches Verhalten über Rückkoppelung zwischen Steuerparameter und Systemvariable - in der vorliegenden Anwendung über den Druck an gegebener Stelle im Netz - bestimmt ist. Bisher war kein geschlossenes mathematisches Modell bekannt, welches die Berücksichtigung dieser Anlagen gestattete. Ein rigoroser Beweis der Eindeutigkeit von Systemzuständen stand aus. Unter diese Kategorie fallen z.B. Druckminderungsventile (PRVs), die selbsttätig (ohne Fremdenergie) den Prozess über eine Sollwertfeder regeln. Das Gleichgewicht, das sich zwischen der Feder und dem Wasserdruck einstellt, wird hier als Minimierungsproblem eines hydrostatischen Potenzials formuliert. Insgesamt ist der stationäre Punkt durch die Lösungen der sich gegenseitig beeinflussenden Minimierungsprobleme des hydrostatischen Potenzials und des System-\u27Content\u27 beschrieben. Im Rahmen dieser Arbeit wird der Versuch unternommen, das sogenannte Nash-Konzept der Spieltheorie auf ein technisches Problem anzuwenden. Notwendige und hinreichende Bedingungen für die Eindeutigkeit eines Gleichgewichts werden gegeben. Die Eindeutigkeit der Lösung ermöglicht Aussagen über Parametersensitivitäten entsprechend denen der Nichtlinearen Optimierung. Schließlich werden Beispiele für Anwendungsmöglichkeiten des entwickelten Modells gegeben und der Einsatz innerhalb des Kalibrierungsprozesses zur Modelleichung oder Mängelanalyse skizziert. Abstract Water supply networks represent an important part of the urban technical infrastructure. As a consequence of the capacity increase of personal computers over the last decades, also research and development of water supply network systems analysis was enhanced. This refers, in particular, to specific areas such as Network design optimization including rehabilitation and extension, Simulation of the daily operation and Calibration of simulation models. A distinct separation of those subject areas is difficult to define, especially, the two last mentioned subjects are related and intertwine. This study is to focus upon the simulation of the steady state in reticulate water supply networks. Non-steady state hydraulics are not considered due to the existing low velocities in water supply networks. Time extended analysis is taken into account by assuming a sequence of steady state approximations. In reality, water supply networks contain a multitude of control devices. The objectives of their application vary from supporting rehabilitation of deficient network components, working towards energy-saving, helping with leak detection and control, data collection, allocation of gauging points for model calibration, etc. Three categories may be identified as to the hydraulics of those control devices: i) hydraulics and operating state are known prior to simulation ii) hydraulics are known, operating state is unknown prior to simulation iii) hydraulics and operating state are unknown prior to simulation (feedback devices). In this study, first, without referring to specific devices, the equilibrium conditions of the steady state are described for a reticulate system (synthesis approach). Second, an alternative approach is discussed representing an equivalent mathematical model formulated as an optimization problem (analysis approach). This second approach offers the advantage to answering questions as to the existence and uniqueness of the hydraulic equilibrium. Also, available optimization algorithms can be applied, sensitivity analyses can be conducted. The resulting model turns out to be a convex nonlinear minimization problem without constraints (minimization of the \u27system-content\u27). It reflects the state of the art of analytical methods with respect to the definition of sufficient and necessary conditions of the hydraulic equilibrium of reticulate pipe networks, allowing to include control devices like tanks, throttle control valves and pumps with known hydraulics. The subsequent step of this study is devoted to including control devices of type i) and ii). Thus, linear equality and inequality constraints are added to the model, and the concept of sub-gradients is introduced. The resulting mathematical framework of the problem is analyzed yielding, again, general necessary and sufficient conditions required to define convexity of the problem. This extension of the model allows to account for control valves, check valves, temporary closed valves. Simulation of certain system\u27s deficiencies, e.g. of pressure dependent leakage and intermittend supply, is made possible. Sensitivity analyses via Parametric Nonlinear Programming can be employed to assess the impact of parameter changes upon systems variables. The final section of the study treats devices of type iii) whose hydraulic behaviour is characterised by a feedback between control parameters and systems variables, the latter being, e.g., the pressure at given points of the network. So far, a mathematical approach was not available to include these devices. A rigorous proof of the uniqueness of resulting system states had not been derived. An example of this category are pressure reducing valves (PRVs) operated \u27self-acting\u27 by a set-value spring. It is shown that the equilibrium between spring force and water pressure can be formulated as a minimzation problem of a hydrostatic potential. The equilibrium point is reached by solving mutually interacting minimization problems of the hydrostatic potential and the \u27system-content\u27. The approach applies the so called Nash-concept of Game Theory to a technical system. This way, again, necessary and suÆcient conditions for uniqueness of the hydraulic equilibrium are determined. The model also delivers parameter sensitivities as a result of uniqueness of the Nash-equilibrium according methods of Parametric Nonlinear Programming. Examples of model application are presented, eventually, and special reference is given to the model\u27s capacity in the realm of network deciency analysis and network calibration

Estimation de la demande pour les réseaux d'alimentation en eau potable : résolution d'un problème sous-déterminé par des algorithmes génétiques

International audienceModeling of water distribution systems is fundamental for the design, analysis and operation of any water network. As with all hydraulic models, water demands are one of the most important input components in the model. However, estimation of the demand parameters is usually complicated due to the stochastic behavior of the water consumptions. Several methods have been proposed for estimating water demands. Most of them have been developed based on given frameworks where the number of unknown parameters is assumed to be equal or less than the number of measurements. The outcomes, therefore, rely on this assumption, which can lead to significant approximation errors in real water distribution systems. The approach proposed in this paper does not require the number of known inputs to be equal to the number of variables. In fact, nodes in the model could each have a different demand pattern. The genetic algorithm approach adopted here shows that the average results of multiple GA runs can estimate the demand patterns at each node. Moreover, the model can also be used to estimate the flow rates and nodal heads at non-measured locations of the water network, although the accuracy of the estimation depends on number, type and location of the measurements. Results are shown and discussed for a literature case study tested for a 24-hour time period

Des indicateurs clés de performances pour accroître la résilience des réseaux sur trois étapes

International audienceWater distribution networks (WDNs) are critical infrastructures that should face multiple and continuous changes and adverse operative conditions (due to abnormal events) that alter their normal service provision. The main objective of a WDN is to deliver the required amount of water to the customer under a certain threshold of the desired pressure and quality. Therefore, ensuring resilience and safety of WDSs are big concerns for water utilities. Several resilience key performance indicators have been suggested to quantify and assessing WDN resilience. Regarding the objectives of resilience, water utility managers require modelling tools to be able to predict how the WDN will perform during disruptive events and understand how the system can better absorb them. Tools such as: demand-driven modelling (DDM) for sufficient pressure conditions, and pressure-driven modelling (PDM) for insufficient pressure conditions, aid to simulate WDNs performance under adverse operative conditions. This work attempts to evaluate the network resilience. The proposed approach is based on an event-driven methodology and there is considered the time when the event occurs, when it evolves, and the sequence of the events. It should be carefully selected the type of the approach (PDM or DDM) used for the hydraulic model, as well as the system performance state and the uses of resilience power-based indicators. The results are promising in order to provide to water managers with a great depth of information and support better preparedness for WDNs

Évaluation de la phase absorbante de résilience basée sur des Indicateurs de criticité pour des réseaux de distribution d'eau

International audienceWater distributions networks (WDNs) are exposed to multiple hazards, leading the network to operate under a range of critical conditions. This paper explored the relationship between the impact of anomalous events (AEs) of WDNs and the consequent palliative actions (PAs) to be implemented in the network to minimize such impact. Both AEs and PAs were assessed through a network resilience criticality index adapted to WDNs. The results were compared with those obtained from normal operating conditions with respect to the satisfaction rate of nodal demands. The proposal was evaluated by two case studies. The first corresponded to a small synthetic network and the second to a medium-size utility network. After a pipe burst event analysis, two different isolation actions were scrutinized in each of the two WDNs. The results quantify system resilience and support water utility managers in further decision-making processes. This is done through critical resilience indicators that provide information and support for better crisis preparedness (planning) and management (mitigation)

Fast graph matrix partitioning algorithm for solving the water distribution system equations

In this paper a method which determines the steady-state hydraulics of a water distribution system, the Graph Matrix Partitioning Algorithm (GMPA), is presented. This method extends the technique of separating the linear and nonlinear parts of the problem and using the more time consuming nonlinear solver only on the nonlinear parts of the problem and faster linear techniques on the linear parts of the problem. The previously developed Forest-Core Partitioning Algorithm (FCPA) used this approach to separate the network graph's external forest from its looped core but did not address the fact that within the core of a network graph there may be many internal trees - nodes in series - for which a more economical linear process can be used. This extension of the separation process can significantly reduce the dimension of the nonlinear problem that must be solved: GMPA applied to eight case study networks with between 900 and 20,000 pipes show reductions to between 5% and 55% of the core dimension (after FCPA). The separation of the problem into its nonlinear and linear parts involves no approximations, such as lumping or skeletonization, and the resulting solution is precisely the solution that would have been obtained by the slower technique of solving the entire network with a nonlinear solver. The new method is applied after the network has been separated into an external forest and core by the FCPA method. The GMPA identifies all the nodes in the core which are in series (the internal forest) and then iterates alternately on the remaining core (the (nonlinear) global step) and the internal forest (the (linear) local step). In this paper, it is formally shown that the smaller set of nonlinear equations in the GMPA corresponds to the network equations of a particular topological subgraph of the original graph. Using algebraic manipulations, the size of the linearized system to be solved is reduced to the number of nodes in the core having degree greater than two. For pipe models of real world applications that are derived from GIS datasets, this can mean a dramatic reduction of the size of the nonlinear problem that has to be solved. The main contributions of the paper are (i) the derivation and presentation of formal proofs for the new method and (ii) demonstrating how significant the reduction in the dimension of the nonlinear problem can be for suitable networks. The method is illustrated on a simple example.J. Deuerlein, S. Elhay, and A. R. Simpso

The never ending story of modeling control-devices in hydraulic systems analysis

Difficulties of simulation in existing hydraulic models arising from combinations of pressure and flow controlling devices in water distribution systems have been discussed in a number of previous papers. For instance, examples for non-convergence or wrong results of the hydraulic solver EPANET (version 2.00.10) were first published by Simpson in 1999. It may be shown that the problems were caused by a singularity of the equation system that appears if in an iteration two interacting control devices are active at the same time. In terms of graph theory the part of the network between the two active valves in this case is disconnected from the rest of the system leading to the singularity. In the new EPANET version 2.00.12 that has been released recently this problem is tackled by adding a virtual coefficient to all matrix columns and rows corresponding to nodes of active flow control valves. Mathematically this method is equivalent to adding a very small diameter pipe to the actual network in parallel to the FCV resulting in a nonsingular system. The examples of networks published by Simpson (1999) where EPANET 2.00.10 failed to converge or converged to wrong results now can be solved successfully. Nevertheless the latest release of EPANET still has difficulties in modeling of combinations of control devices. Whereas the former version of EPANET (version 2.00.10) often failed to calculate the correct valve states (active, closed, open) the problems of the new version consist of numerical inexactness that is caused by the addition of the virtual matrix terms for FCVs. In addition examples can be found where version 2.00.12 of EPANET still fails to converge. ©ASCE 2009.Jochen Deuerlein, Angus R. Simpson and Egbert Gros