L'un des challenges le plus important pour les opérateurs des réseaux mobiles est de dimensionner le réseau de la manière la plus efficace possible, c'est-à-dire, bien planifier les ressources pour fournir une bonne couverture et une meilleure capacité. Afin de mieux gérer le trafic généré dans le réseau, les opérateurs déploient des petites cellules pour aider les macro-cellules à délester les zones de la cellule où le trafic de données est significativement supérieur au trafic moyen dans la cellule. Cependant, le problème majeur de ces réseaux hétérogènes consiste à bien localiser ces hotspots et puis de mettre en place la meilleure solution pour les absorber. Dans cette thèse, on traite le sujet de localisation de hotspot et on étudie l'impact de son imperfection sur les performances des déploiements des réseaux hétérogènes. Dans une première étape, on propose une nouvelle méthode de localisation de hotspot. Puis, on propose d'évaluer l'impact d'une mauvaise localisation de trafic sur le déploiement des petites cellules à travers une analyse de performances au niveau statique et dynamique. Sachant qu'une grande quantité de trafic de données dans le réseau mobile est générée par des utilisateurs qui sont en mouvement, on propose d'évaluer les performances des petites cellules mobiles. Enfin, la quatrième étape consiste à améliorer encore la solution de déploiement de petites cellules en utilisant les drones. On propose un mécanisme de décongestion du réseau et on discute les avantages et les points à explorer. Une analyse de performance est aussi réalisée pour comparer cette solution avec les solutions classiques de macro cellules et de petites cellules / The continuous increasing traffic in cellular networks has forced the mobile operators to look for efficient and viable options to manage their networks so as to ensure more efficiency over the network life cycle while also evolving with the implementation of new technologies. Traffic hotspot localization can help operators to identify the areas where deploying small cells can reduce the congestion. We firstly propose and assess a new traffic hotspot localization method based on the projection of O&M KPIs on the coverage map. Compared to probing methods, the computational costs and the equipment expenditures are reduced. Moreover, the localization accuracy is improved. Next, in order to evaluate the impact of the limited accuracy of traffic localization tools on small cell deployment, we study the performances of three different scenarios. The first one considers a network of macrocells only and represents a benchmark to decide about the usefulness of small cells. The second one is based on a network of macrocells with a perfectly deployed small cell allowing to identify the limitations of small cell deployment and the last one is with an imperfectly deployed small cell. Realizing that a significant amount of cellular demand is generated on the go and suffers deteriorating quality, we investigate the potential performance gains of using moving small cells. The major outcome is to understand if moving cells leverage the relative operators' investments. Finally, we propose a new mobile data offloading mechanism which capitalizes on drone small cells to alleviate the data traffic load. We realize a performance evaluation and comparison with classic small cell deployment

Indiana University-Purdue University Indianapolis (IUPUI) / Law enforcement agencies across the U.S. use maps of crime to inform their practice and make efforts to reduce crime. Hotspot maps using historic crime data can show practitioners concentrated areas of criminal offenses and the types of offenses that have occurred; however, not all of these hotspot crime mapping techniques produce the same results. This study compares three hotspot crime mapping techniques and four crime types using the Predictive Accuracy Index (PAI) to measure the predictive accuracy of these mapping techniques in Marion County, Indiana. Results show that the grid hotspot mapping technique and crimes of robbery are most predictive. Understanding the most effective crime mapping technique will allow law enforcement to better predict and therefore prevent crimes.

<p>  </p> <p>Heat pipes and vapor chambers are passive two-phase heat transport devices that are used for thermal management in electronics. The passive operation of a heat pipe is facilitated by capillary wicking of the working fluid through a porous wick, and thus is subject to an operational limit in terms of the maximum pressure head that the wick can provide. This operational limit, often termed as the capillary limit, is the maximum heat input at which the pressure drop in the wick is balanced by the maximum capillary pressure head; operating a heat pipe or a vapor chamber above the capillary limit at steady-state leads to dryout. It thus becomes important to predict the performance of heat pipes and vapor chambers and explore the parametric design space to provide guidelines for minimized thermal resistance while satisfying this capillary limit. An increasingly critical aspect is to predict the transient thermal response of vapor chambers. Moreover, heat pipes and vapor chambers are extensively being used in electronic systems where the power input is dictated by the end-user activity and is expected to even exceed the capillary limit for brief time intervals. Thus, it is imperative to understand the behavior of heat pipes and vapor chambers when operated at steady and transient heat loads above the capillary limit as dryout occurs. However, review of the literature on heat pipe performance characterization reveals that the regime of dryout operation has been virtually unexplored, and thus this thesis aims to fill this critical gap in understanding.</p> <p>The design for minimized thermal resistance of a vapor chamber or a heat pipe is guided by the relative contribution of thermal resistance due to conduction across the evaporator wick and the saturation temperature gradient in the vapor core. In the limit of very thin form factors, the contribution from the vapor core thermal resistance dominates the overall thermal resistance of the vapor chamber; recent work has focused on working fluid selection to minimize overall thermal resistance in this limit. However, the wick thermal resistance becomes increasingly significant as its thickness increases to support higher heat inputs while avoiding the capillary limit. A thermal resistance network model is thus utilized to investigate the importance of simultaneously considering the contributions of the wick and vapor core thermal resistances. A generalized approach is proposed for vapor chamber design which allows <em>simultaneous</em> selection of the working fluid and wick that provides minimum overall thermal resistance for a given geometry and operating condition. While the thermal resistance network model provides a convenient method for exploring the design space, it cannot be used to predict 3-D temperature fields in the vapor chamber. Moreover, such thermal resistance network models cannot predict transient performance and temperature evolution for a vapor chamber. Therefore, an easy-to-use approach is proposed for mapping of vapor chamber transport to the heat diffusion equation using a set of appropriately defined effective anisotropic thermophysical properties, thus allowing simulation of vapor chamber as a sold conduction block. This effective anisotropic properties approach is validated against a time-stepping analytical model and is shown to have good match for both spatial and transient temperature predictions.</p> <p>Moving the focus from steady-state and transient operation of vapor chambers, a comprehensive characterization of heat pipe operation above capillary limit is performed. Different user needs and device workloads can lead to highly transient heat loads which could exceed the notional capillary limit for brief time intervals. Experiments are performed to characterize the transient thermal response of a heat pipe subjected to heat input pulses of varying duration that exceed the capillary limit. Transient dryout events due to a wick pressure drop exceeding the maximum available capillary pressure can be detected from an analysis of the measured temperature signatures. It is discovered that under such transient heating conditions, a heat pipe can sustain heat loads higher than the steady-state capillary limit for brief periods of time without experiencing dryout. If the heating pulse is sufficiently long as to induce transient dryout, the heat pipe may experience an elevated steady-state temperature even after the heat load is reduced back to a level lower than the capillary limit. The steady-state heat load must then be reduced to a level much below the capillary limit to fully recover the original thermal resistance of the heat pipe. The recovery process of heat pipes is further investigated, and a mechanism is proposed for the thermal hysteresis observed in heat pipe performance after dryout. A model for <em>steady-state</em> heat pipe transport is developed based on the proposed mechanism to predict the parametric trends of thermal resistance following recovery from dryout-induced thermal hysteresis, and the model is mechanistically validated against experiments. The experimental characterization of the recovery process demonstrates the existence of a maximum hysteresis curve, which serves as the worst-case scenario for thermal hysteresis in heat pipe after dryout. Based on the learnings from the experimental characterization, a new procedure is introduced to experimentally characterize the steady-state dryout performance of a heat pipe.</p> <p>To recover the heat pipe performance under steady-state, it has been shown that the heat input needs to be lowered down or <em>throttled</em> significantly below the capillary limit. However, due to the highly transient nature of power dissipation from electronic devices, it becomes imperative to characterize heat pipe recovery from dryout under transient operations. Hence, power-throttling assisted recovery of heat pipe from dryout has been characterized under transient conditions. A minimum throttling time interval, defined as time-to-rewet, is identified to eliminate dryout induced thermal hysteresis using power throttling. Dependence of time-to-rewet on throttling power is explored, and guidelines are presented to advise the throttling need and choice of throttling power under transient conditions. </p> <p>The experimental characterization of heat pipe operation at pulse loads above the capillary limit and power throttling following the pulse load helped define the dryout and recovery performance of a heat pipe. Next, a physics-based model is developed to predict the heat pipe <em>transient</em> thermal response under dryout-inducing pulse load and power throttling assisted recovery. This novel model considers wick as a partially saturated media with spatially and temporally varying liquid saturation, and accounts for the effect of wick partial saturation in heat pipe transport. The model prediction are validated against experiments with commercial heat pipe samples, and it is shown that the model can accurately predict dryout and recovery characteristics, namely time-to-dryout, time-to-rewet, and dryout-induced thermal hysteresis, for heat pipes with a range of wick types, heat pipe lengths and pulse loads above the capillary limit. </p> <p>The work discussed in this thesis opens certain questions that are expected to guide further research in this area. First, the thermal hysteresis mechanism proposed could be further validated with direct visualization of the liquid in a vapor chamber. To achieve this, X-ray microscopy is proposed as a viable option for the imaging <em>in situ</em> wetting dynamics in a vapor chamber. Second, the model developed to predict the dryout and recovery characteristics of the heat pipe can be used to design heat pipe with improved performance under pulse loads and power throttling. Third, novel wick designs can be explored that utilize the understanding developed of governing mechanisms for recovery from dryout, and can eliminate thermal hysteresis at powers closer to capillary limit. Fourth, the modeling approach can be extended to predict dryout and recovery trends in vapor chamber since the heat transfer pathways in a vapor chamber are different than those of a heat pipe. Fifth, and lastly it was observed several times during experiments that some of the heat pipe samples would exhibit complete dryout (sudden catastrophic rise in temperature and thermal resistance at the point of dryout) whereas other samples would exhibit partial dryout (noticeable but small increase in thermal resistance at dryout) at operating powers just above the capillary limit. Exploring and explaining the cause of complete dryout, in particular, would be an extremely valuable contribution to the heat pipe research. </p> <p>The work discussed in this thesis has led to the comprehensive development of a functional and mechanistic understanding of heat pipe operation above the notional capillary limit. The experimental procedures developed in this work are utilized to characterize a heat pipe performance under dryout and recovery. The models based on the mechanistic understanding developed from experimental characterization of dryout and recovery operation of a heat pipe have been experimentally validated and are useful for predicting heat pipe performance under dryout-inducing pulse loads and power-throttling.   </p>

Undichte Abwassersysteme sind in unserer urbanisierten Welt allgegenwärtig, und aufgrund ihrer versteckten Infrastruktur und der schwierigen Überwachung bleiben ihre Leckagen oft in der Anfangsphase unbemerkt. Trotz der umfangreichen technologischen Entwicklung bei den Kanalinspektionsmethoden und den dazugehörigen Techniken ist die Überwachung von Abwasserkanälen auf städtischer Ebene nach wie vor kostspielig und schwierig. Daher werden ein Empfehlungsverfahren und eine Methodenklassifizierung benötigt, um einen nachhaltigen und kosteneffizienten Kanalinspektionsplan auf Stadtebene zu erstellen. In diesem Zusammenhang kann diese Studie im Wesentlichen in drei Teile gegliedert werden. Zunächst wurde eine umfassende Literaturstudie zu den verfügbaren Kanalinspektionsmethoden durchgeführt, um ein umfassenderes Verständnis für deren Wirkungsbereich und technischen Grad zu erhalten. Darüber hinaus wurden diese Inspektionsmethoden auf der Grundlage ihres Wirkungsbereichs in drei Stufen eingeteilt, wobei Stufe 1 die Methoden mit dem größten Wirkungsbereich umfasst, wie z. B. die Verschlechterungsmodellierung, die ein umfassendes und dennoch zuverlässiges Verständnis der Integrität des Abwassersystems ermöglicht. Stufe 2 bietet intermediäre Inspektionsmethoden wie Wärmebildaufnahmen aus der Luft und geoelektrische Inspektionstechniken, die eine zerstörungsfreie Inspektion, der von Stufe 1 vorgeschlagenen Bereiche ermöglichen. Bei den Methoden der Stufe 3 handelt es sich in erster Linie um Inspektionstechniken in der Rohrleitung, die häufig eine Rohrentwässerung erfordern und im Gegenzug für eine hohe Erkennungsgenauigkeit kostspielig zu implementieren sind. Zweitens wurde als Beitrag zu den Tier-1-Methoden das Vulnerability Hotspot Mapping entwickelt, ein GIS-gestütztes Modell, das die am häufigsten von den Entleerungsmodellen verwendeten Faktoren berücksichtigt und Bereiche des Abwassersystems anbietet, die besonders anfällig für Leckagen sind. Die Validierungs- und Sensitivitätsanalysen ergaben, dass die Fließgeschwindigkeit, das Rohralter und die Oberflächenvegetation die sinnvollsten Faktoren für das Modell sind. Darüber hinaus ergab das lineare Modell einen Wirkungsgrad von 76 % und einen mittleren quadratischen Fehler von 0,918, während es durch den Random-Forest-Algorithmus mit 400 Bäumen verbessert wurde, was auf das Potenzial der Schwachstellen-Kartierung als frühzeitige Methode zur Kanalinspektion auf Stadtebene hinweist. Drittens wurden die Tier-2-Methoden aktualisiert, indem das Potenzial der elektrischen Widerstandstomographie und der Mise-la-masse-Techniken als geoelektrische und zerstörungsfreie Methoden hervorgehoben wurde, die experimentell in einem Holzrahmen mit einer Matrix aus Sensoren und Elektroden getestet wurden. Der Versuchsbehälter besteht aus drei Schichten von Elektroden in gesättigten und ungesättigten Zonen, in denen verschiedene Leckageszenarien durchgeführt wurden, um die Sichtbarkeit von Leckagen mit diesen Methoden zu untersuchen. Trotz der Fähigkeit dieser Methoden zur Leckageerkennung wurde festgestellt, dass die elektrische Widerstandstomographie eine höhere Leckageerkennungsempfindlichkeit als die Mise à la masse hat, während sie eine geringere Flexibilität bietet, was ein wichtiger Punkt bei der Methodenauswahl ist. Darüber hinaus wurde festgestellt, dass Mise à-la-masse empfindlicher auf das Vorhandensein von Leckagen reagiert als auf Feuchtigkeits- und Temperaturschwankungen, was zu einem Pearson's r und R2 von 0,8 bzw. 0,7 im Vergleich zu den während der Leckageszenarien gesammelten Daten führte. Insgesamt schlägt diese Studie vor, dass mindestens zwei (vorzugsweise drei) Inspektionstechniken, die zu verschiedenen Ebenen gehören, eingesetzt werden sollten, um einen nachhaltigen Inspektionsplan auf Stadtebene zu haben. Der vorgeschlagene Ansatz hilft dabei, ein Gleichgewicht zwischen Kosten und Präzision sowie ein Gleichgewicht zwischen Zeit und Einwirkungsbereich herzustellen, was einen dezentralisierten und nachhaltigen Inspektionsplan ermöglicht.:List of Abbreviations .......................................................................................... IX List of Peer-Reviewed Publications on the Ph.D. Topic .................................. X List of Co-authored Peer-Reviewed Publications on the Ph.D. Topic ............ X 1 General Introduction........................................................................... 1 1.1 Background ....................................................................................................... 1 1.2 Aim and Objectives .......................................................................................... 3 1.3 Structure of the Document ............................................................................. 3 2 Towards a Decentralized Solution for Sewer Leakage Detection .............................................................................................. 8 2.1 Introduction ...................................................................................................... 10 2.2 Sewer inspection methods (SIMs) overview ................................................. 11 2.2.1 Tier-one (T-I) ................................................................................................................. 11 Deterioration models ....................................................................................................... 12 Hotspot mapping .............................................................................................................. 14 2.2.2 Tier-two (T-II) methods ............................................................................................... 15 Aerial thermal imaging (ATI) ............................................................................................ 15 Ground penetration radar (GPR) .................................................................................... 16 Electrical resistivity tomography (ERT) ........................................................................... 17 Mise-à-la-masse method (MLM)...................................................................................... 18 Soil Sampling ..................................................................................................................... 18 2.2.3 Tier-three (T-III) methods ........................................................................................... 20 General approaches ......................................................................................................... 20 Laser scanning ................................................................................................................... 21 Visual inspection ............................................................................................................... 21 Acoustic methods ............................................................................................................. 22 Ultrasonic inspection ........................................................................................................ 24 Multi-sensor robots .......................................................................................................... 24 Electromagnetic Inspection ............................................................................................. 26 Thermography Inspection ............................................................................................... 26 Tracer Test ......................................................................................................................... 27 VII 2.3 Discussion.......................................................................................................... 30 2.4 Conclusion and outlook ................................................................................... 33 2.5 References ......................................................................................................... 34 3 Vulnerability Hotspot Mapping (VHM) of Sewer Pipes based on Deterioration Factors .................................................................... 42 3.1 Introduction ...................................................................................................... 43 3.2 Materials and Methods.................................................................................... 44 3.2.1 Overview of the sewer deterioration factors. .......................................................... 45 Pipe Age .............................................................................................................................. 46 Pipe Material ...................................................................................................................... 47 Sewer Type ......................................................................................................................... 48 Flow Velocity ...................................................................................................................... 48 Node Degree...................................................................................................................... 49 Surface Vegetation ............................................................................................................ 50 Criticality class and weighting matrix ............................................................................. 50 3.3 Case study ......................................................................................................... 52 3.4 Results and discussions ................................................................................... 54 3.4.1 Network assessment .................................................................................................. 54 3.4.2 Validation and sensitivity analysis ............................................................................ 56 3.5 Summary and conclusion ................................................................................ 61 3.6 Reference........................................................................................................... 63 4 Laboratory Application of the Mise-à-la-Masse (MALM) for Sewer Leakage Detection as an intermediary inspection method. ................................................................................................ 67 4.1 Introduction ...................................................................................................... 68 4.2 Methodology ..................................................................................................... 70 4.2.1 Mise-à-la-Masse method (MALM) .............................................................................. 70 4.2.2 Experimental setup ..................................................................................................... 70 4.2.3 Measurement principles ............................................................................................ 72 4.2.4 Assessed Scenarios ..................................................................................................... 73 4.3 Results and discussions ................................................................................... 74 VIII Inhaltsverzeichnis 4.3.1 Contour Visualization ................................................................................................. 74 First Leakage scenario ...................................................................................................... 74 Other leakage scenarios .................................................................................................. 75 4.3.2 Trend Analyses ............................................................................................................ 77 Leakage proximity ............................................................................................................. 77 Vertical Assessment .......................................................................................................... 78 4.3.3 Data Validation and Sensitivity Analyses ................................................................. 79 Data Validation .................................................................................................................. 79 Sensitivity Analyses ........................................................................................................... 80 4.3.4 Application in practice ................................................................................................ 82 4.4 Summary and Conclusion ............................................................................... 83 4.5 References ......................................................................................................... 85 5 Conclusions and Outlooks .................................................................. 88 5.1 Discussion and Conclusions ............................................................................ 88 5.2 Outlooks ............................................................................................................ 89 6 Supplementary Information ............................................................... 92 / Leaky sewer systems are present in our urbanized world and due to their hidden infrastructure and monitoring challenges, their leakages tend to remain unnoticed often at initial stages. Despite an extensive technological development in sewer inspection methods and their implemented techniques, sewer monitoring at the city scale remains costly and challenging. Therefore, a recommendation procedure and method classification are needed to have a sustainable and cost-effective sewer inspection plan at the city scale. In this context, this study can be mainly divided into three parts. First, an extensive study literature was conducted on available sewer inspection methods to have a wider understanding on their area of impacts and technicality levels, Furthermore, these inspection methods were categorized into three tiers based on their area of impact where Tier-1 consists of largest area of impact methods such as deterioration modelling, which provide a vast yet reliable understanding of the sewer system integrity. Tier-2 offers intermediatory inspection methods such as aerial thermal imagery and geo-electrical inspection techniques, which can provide a non-destructive inspection on areas suggested from Tier-1 techniques. Following the area of impact, Tier-3 methods are mostly in-pipe inspection techniques, which often demand pipe dewatering and are costly to implement in returns of a high detection precision. Second, as a contribution to Tier-1 methods, Vulnerability Hotspot Mapping was developed, which is a GIS-based model according to the most frequently used factors by deterioration models and offers areas of the sewer system more prone to leakage. The validation and sensitivity analyses revealed that flow velocity, pipe age, and surface vegetation are the most sensible factors to the model respectively. Furthermore, the linear model resulted in 76% of efficiency and mean squared error of 0,918 while it was improved with random forest algorithm with 400 trees, which points out the vulnerability mapping potential as an early sewer inspection method at the city scale. Third, Tier-2 methods were updated by emphasizing on the potential of Electrical Resistivity Tomography and Mise à-la-masse techniques as geo-electrical and non-destructive methods, which were experimentally tested within a wooden frame with a matrix of sensors and electrodes implemented. The experimental tank consists of three layers of electrodes in saturated and unsaturated zones, when various leakage scenarios were conducted to investigate on leakage visibility by these methods. Despite the capability of these methods for leakage detection, it was assessed that Electrical Resistivity Tomography has higher leakage detection sensibility than Mise à-la-masse while offering less mobility, which is a considerable point in method selection process. Moreover, it was observed that Mise à-la-masse is more sensitive to leakage presence rather than humidity and temperature variations and resulted in 0.8 and 0.7 in Pearson’s r and R2 respectively in comparison to sampled data during the leakage scenarios. All over, this study suggests that at least two (preferably 3) inspection techniques belonging to different tiers should be implemented to have a sustainable inspection plan at the city scale. The proposed approach helps to have a balance between cost and precision as well as an equilibrium between time and area of impact, which provides a decentralized and sustainable inspection plan.:List of Abbreviations .......................................................................................... IX List of Peer-Reviewed Publications on the Ph.D. Topic .................................. X List of Co-authored Peer-Reviewed Publications on the Ph.D. Topic ............ X 1 General Introduction........................................................................... 1 1.1 Background ....................................................................................................... 1 1.2 Aim and Objectives .......................................................................................... 3 1.3 Structure of the Document ............................................................................. 3 2 Towards a Decentralized Solution for Sewer Leakage Detection .............................................................................................. 8 2.1 Introduction ...................................................................................................... 10 2.2 Sewer inspection methods (SIMs) overview ................................................. 11 2.2.1 Tier-one (T-I) ................................................................................................................. 11 Deterioration models ....................................................................................................... 12 Hotspot mapping .............................................................................................................. 14 2.2.2 Tier-two (T-II) methods ............................................................................................... 15 Aerial thermal imaging (ATI) ............................................................................................ 15 Ground penetration radar (GPR) .................................................................................... 16 Electrical resistivity tomography (ERT) ........................................................................... 17 Mise-à-la-masse method (MLM)...................................................................................... 18 Soil Sampling ..................................................................................................................... 18 2.2.3 Tier-three (T-III) methods ........................................................................................... 20 General approaches ......................................................................................................... 20 Laser scanning ................................................................................................................... 21 Visual inspection ............................................................................................................... 21 Acoustic methods ............................................................................................................. 22 Ultrasonic inspection ........................................................................................................ 24 Multi-sensor robots .......................................................................................................... 24 Electromagnetic Inspection ............................................................................................. 26 Thermography Inspection ............................................................................................... 26 Tracer Test ......................................................................................................................... 27 VII 2.3 Discussion.......................................................................................................... 30 2.4 Conclusion and outlook ................................................................................... 33 2.5 References ......................................................................................................... 34 3 Vulnerability Hotspot Mapping (VHM) of Sewer Pipes based on Deterioration Factors .................................................................... 42 3.1 Introduction ...................................................................................................... 43 3.2 Materials and Methods.................................................................................... 44 3.2.1 Overview of the sewer deterioration factors. .......................................................... 45 Pipe Age .............................................................................................................................. 46 Pipe Material ...................................................................................................................... 47 Sewer Type ......................................................................................................................... 48 Flow Velocity ...................................................................................................................... 48 Node Degree...................................................................................................................... 49 Surface Vegetation ............................................................................................................ 50 Criticality class and weighting matrix ............................................................................. 50 3.3 Case study ......................................................................................................... 52 3.4 Results and discussions ................................................................................... 54 3.4.1 Network assessment .................................................................................................. 54 3.4.2 Validation and sensitivity analysis ............................................................................ 56 3.5 Summary and conclusion ................................................................................ 61 3.6 Reference........................................................................................................... 63 4 Laboratory Application of the Mise-à-la-Masse (MALM) for Sewer Leakage Detection as an intermediary inspection method. ................................................................................................ 67 4.1 Introduction ...................................................................................................... 68 4.2 Methodology ..................................................................................................... 70 4.2.1 Mise-à-la-Masse method (MALM) .............................................................................. 70 4.2.2 Experimental setup ..................................................................................................... 70 4.2.3 Measurement principles ............................................................................................ 72 4.2.4 Assessed Scenarios ..................................................................................................... 73 4.3 Results and discussions ................................................................................... 74 VIII Inhaltsverzeichnis 4.3.1 Contour Visualization ................................................................................................. 74 First Leakage scenario ...................................................................................................... 74 Other leakage scenarios .................................................................................................. 75 4.3.2 Trend Analyses ............................................................................................................ 77 Leakage proximity ............................................................................................................. 77 Vertical Assessment .......................................................................................................... 78 4.3.3 Data Validation and Sensitivity Analyses ................................................................. 79 Data Validation .................................................................................................................. 79 Sensitivity Analyses ........................................................................................................... 80 4.3.4 Application in practice ................................................................................................ 82 4.4 Summary and Conclusion ............................................................................... 83 4.5 References ......................................................................................................... 85 5 Conclusions and Outlooks .................................................................. 88 5.1 Discussion and Conclusions ............................................................................ 88 5.2 Outlooks ............................................................................................................ 89 6 Supplementary Information ............................................................... 92

The central issue of this research revolves around the implementation of sector policing in the province of KwaZulu-Natal. The research is based in two police stations, that is, Nongoma and Newcastle. Sector policing is a policing strategy introduced by South African Police Service in 1994. The aim of this policing strategy is the creation of structured consultation with regards to local crime problems between the police and respective communities. The objective of sector policing is to develop an organizational structure and environment that reflects community values and facilitates community involvement in addressing risk factors and solve crime-related problems. The research problem for this study is that there is little or no research conducted on the implementation of sector policing in South Africa in general and Nongoma and Newcastle in particular. Following this problem statement, the following five research questions were formulated: What is sector policing and how does its implementation differ between the USA, the UK and South Africa? What is the status of the implementation of the sector policing in South Africa, in particular the Province of KwaZulu-Natal? What are the challenges experienced in implementing sector policing in Nongoma and Newcastle police stations? What are best practices that can be observed in the implementation of sector policing in these two police stations? What is the best possible way of implementing sector policing in South Africa? The aim of the research is to assess and describe the manner in which sector policing was implemented in the two police stations in KZN. The research findings obtained through interviews are analysed and interpreted. In view of the findings, best practices, and recommendations were formulated on how to overcome challenges that may face the implementation of sector policing in the province of KwaZulu-Natal. / Public Administration & Management / M.Tech. (Public Administration & Management)

The central issue of this research revolves around the implementation of sector policing in the province of KwaZulu-Natal. The research is based in two police stations, that is, Nongoma and Newcastle. Sector policing is a policing strategy introduced by South African Police Service in 1994. The aim of this policing strategy is the creation of structured consultation with regards to local crime problems between the police and respective communities. The objective of sector policing is to develop an organizational structure and environment that reflects community values and facilitates community involvement in addressing risk factors and solve crime-related problems. The research problem for this study is that there is little or no research conducted on the implementation of sector policing in South Africa in general and Nongoma and Newcastle in particular. Following this problem statement, the following five research questions were formulated: What is sector policing and how does its implementation differ between the USA, the UK and South Africa? What is the status of the implementation of the sector policing in South Africa, in particular the Province of KwaZulu-Natal? What are the challenges experienced in implementing sector policing in Nongoma and Newcastle police stations? What are best practices that can be observed in the implementation of sector policing in these two police stations? What is the best possible way of implementing sector policing in South Africa? The aim of the research is to assess and describe the manner in which sector policing was implemented in the two police stations in KZN. The research findings obtained through interviews are analysed and interpreted. In view of the findings, best practices, and recommendations were formulated on how to overcome challenges that may face the implementation of sector policing in the province of KwaZulu-Natal. / Public Administration and Management / M.Tech. (Public Administration & Management)

Abstract: Road traffic accidents claim more than 1,500 lives each year in Canada and affect society adversely, so transport authorities must reduce their impact. This is a major concern in Quebec, where the traffic-accident risks increase year by year proportionally to provincial population growth. In reality, the occurrence of traffic crashes is rarely random in space-time; they tend to cluster in specific areas such as intersections, ramps, and work zones. Moreover, weather stands out as an environmental risk factor that affects the crash rate. Therefore, traffic-safety engineers need to accurately identify the location and time of traffic accidents. The occurrence of such accidents actually is determined by some important factors, including traffic volume, weather conditions, and geometric design. This study aimed at identifying hotspot locations based on a historical crash data set and spatiotemporal patterns of traffic accidents with a view to improving road safety. This thesis proposes two new methods for identifying hotspot locations on a road network. The first method could be used to identify and rank hotspot locations in cases in which the value of traffic volume is available, while the second method is useful in cases in which the value of traffic volume is not. These methods were examined with three years of traffic-accident data (2011–2013) in Sherbrooke. The first method proposes a two-step integrated approach for identifying traffic-accident hotspots on a road network. The first step included a spatial-analysis method called network kernel-density estimation. The second step involved a network-screening method using the critical crash rate, which is described in the Highway Safety Manual. Once the traffic-accident density had been estimated using the network kernel-density estimation method, the selected potential hotspot locations were then tested with the critical-crash-rate method. The second method offers an integrated approach to analyzing spatial and temporal (spatiotemporal) patterns of traffic accidents and organizes them according to their level of significance. The spatiotemporal seasonal patterns of traffic accidents were analyzed using the kernel-density estimation; it was then applied as the attribute for a significance test using the local Moran’s I index value. The results of the first method demonstrated that over 90% of hotspot locations in Sherbrooke were located at intersections and in a downtown area with significant conflicts between road users. It also showed that signalized intersections were more dangerous than unsignalized ones; over half (58%) of the hotspot locations were located at four-leg signalized intersections. The results of the second method show that crash patterns varied according to season and during certain time periods. Total seasonal patterns revealed denser trends and patterns during the summer, fall, and winter, then a steady trend and pattern during the spring. Our findings also illustrated that crash patterns that applied accident severity were denser than the results that only involved the observed crash counts. The results clearly show that the proposed methods could assist transport authorities in quickly identifying the most hazardous sites in a road network, prioritizing hotspot locations in a decreasing order more efficiently, and assessing the relationship between traffic accidents and seasons. / Les accidents de la route sont responsables de plus de 1500 décès par année au Canada et ont des effets néfastes sur la société. Aux yeux des autorités en transport, il devient impératif d’en réduire les impacts. Il s’agit d’une préoccupation majeure au Québec depuis que les risques d’accidents augmentent chaque année au rythme de la population. En réalité, les accidents routiers se produisent rarement de façon aléatoire dans l’espace-temps. Ils surviennent généralement à des endroits spécifiques notamment aux intersections, dans les bretelles d’accès, sur les chantiers routiers, etc. De plus, les conditions climatiques associées aux saisons constituent l’un des facteurs environnementaux à risque affectant les taux d’accidents. Par conséquent, il devient impératif pour les ingénieurs en sécurité routière de localiser ces accidents de façon plus précise dans le temps (moment) et dans l’espace (endroit). Cependant, les accidents routiers sont influencés par d’importants facteurs comme le volume de circulation, les conditions climatiques, la géométrie de la route, etc. Le but de cette étude consiste donc à identifier les points chauds au moyen d’un historique des données d’accidents et de leurs répartitions spatiotemporelles en vue d’améliorer la sécurité routière. Cette thèse propose deux nouvelles méthodes permettant d’identifier les points chauds à l’intérieur d’un réseau routier. La première méthode peut être utilisée afin d’identifier et de prioriser les points chauds dans les cas où les données sur le volume de circulation sont disponibles alors que la deuxième méthode est utile dans les cas où ces informations sont absentes. Ces méthodes ont été conçues en utilisant des données d’accidents sur trois ans (2011-2013) survenus à Sherbrooke. La première méthode propose une approche intégrée en deux étapes afin d’identifier les points chauds au sein du réseau routier. La première étape s’appuie sur une méthode d’analyse spatiale connue sous le nom d’estimation par noyau. La deuxième étape repose sur une méthode de balayage du réseau routier en utilisant les taux critiques d’accidents, une démarche éprouvée et décrite dans le manuel de sécurité routière. Lorsque la densité des accidents routiers a été calculée au moyen de l’estimation par noyau, les points chauds potentiels sont ensuite testés à l’aide des taux critiques. La seconde méthode propose une approche intégrée destinée à analyser les distributions spatiales et temporelles des accidents et à les classer selon leur niveau de signification. La répartition des accidents selon les saisons a été analysée à l’aide de l’estimation par noyau, puis ces valeurs ont été assignées comme attributs dans le test de signification de Moran. Les résultats de la première méthode démontrent que plus de 90 % des points chauds à Sherbrooke sont concentrés aux intersections et au centre-ville où les conflits entre les usagers de la route sont élevés. Ils révèlent aussi que les intersections contrôlées sont plus à risque par comparaison aux intersections non contrôlées et que plus de la moitié des points chauds (58 %) sont situés aux intersections à quatre branches (en croix). Les résultats de la deuxième méthode montrent que les distributions d’accidents varient selon les saisons et à certains moments de l’année. Les répartitions saisonnières montrent des tendances à la densification durant l’été, l’automne et l’hiver alors que les distributions sont plus dispersées au cours du printemps. Nos observations indiquent aussi que les répartitions ayant considéré la sévérité des accidents sont plus denses que les résultats ayant recours au simple cumul des accidents. Les résultats démontrent clairement que les méthodes proposées peuvent: premièrement, aider les autorités en transport en identifiant rapidement les sites les plus à risque à l’intérieur du réseau routier; deuxièmement, prioriser les points chauds en ordre décroissant plus efficacement et de manière significative; troisièmement, estimer l’interrelation entre les accidents routiers et les saisons.

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