Video-on-Demand (VoD) is a service that allows people to request and view stored videos or movies of their choice directly online from a VoD service provider. The selected streaming videos are then delivered over the broadband Internet. The bursty nature of Variable-Bit-Rate (VBR) compressed video (such as MPEG) poses some important issues for video delivery over high-speed networks due to its significant bit rate variation over multiple time scales. However, sufficient quality of service (QoS) mechanisms must be in place before it can be widely enabled and deployed over Internet. Conventionally a static bandwidth level close to the peak rate is reserved for a streaming video flow. Any static allocation of network resources for VBR video traffic would be difficult and inefficient considering the peak rate to be significantly higher than the average data rate. Since the traffic pattern over time is already known for pre-recorded videos, this issue is addressed by the Renegotiated Constant Bit Rate (RCBR) service which proposes QoS allocation over multiple time scales. Since this mechanism has been tested via simulations and analysis only we implemented it on a real test bed with a VoD server and clients to study its performance. We observed that under heavy bandwidth constraints the performance of RCBR is much better than traditional CBR in terms of packet loss rate. We also implement a new Adaptive Buffer Window mechanism and the concept of application level smoothing to increase the scalability of a VoD server. / Master of Science

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A smart grid is different from a traditional power system in that it allows incorporation of intelligent features and functions, e.g., meter reading, adaptive demand response, integration of distributed energy sources, substation automation, etc. All these intelligent features and functions are achieved by choosing appropriate communication technologies and network structures for the smart grid appropriately. The objective of this dissertation is to develop an AHP (analytic hierarchy process) - based strategy for demand curtailment allocation that is subject to communications and cyber security limitations. Specifically, it: (1) proposes an electrical demand curtailment allocation strategy to keep the balance between supply and demand in case of the sudden supply shortage; (2) simulates the operation of the proposed demand curtailment allocation strategy considering the impact from communication network limitations and simultaneous operations of multiple smart grid applications sharing the same communication network; and (3) analyzes the performance of the proposed demand curtailment allocation strategy when selected cyber security technologies are implemented. These are explained in more details below. An AHP-based approach to electrical demand curtailment allocation management is proposed, which determines load reduction amounts at various segments of the network to maintain the balance between generation and demand. Appropriate communication technologies and the network topology are used to implement these load reduction amounts down to the end-user. In this proposed strategy, demand curtailment allocation is quantified taking into account the demand response potential and the load curtailment priority of each distribution substation. The proposed strategy helps allocate demand curtailment (MW) among distribution substations or feeders in an electric utility service area based on requirements of the central load dispatch center. To determine how rapidly the proposed demand curtailment strategy can be implemented, the capability of the communication network supporting the demand curtailment implementation needs to be evaluated. To evaluate the capability of different communication technologies, selected communication technologies are compared in terms of their latency, throughput, reliability, power consumption and implementation costs. Since a number of smart grid applications share the same communication network, the performance of this communication network is also evaluated considering simultaneous operation of popular smart grid applications. Lastly, limitations of using several cyber security technologies based on different encryption methods - 3EDS (Triple Data Encryption Standard), AES (Advanced Encryption Standard), Blowfish, etc. - in deploying the proposed demand curtailment allocation strategy are analyzed. / Ph. D. / With the rapid development of smart grid, the penetration of renewable energy resources is higher than ever and keeps growing. However, the output of such variable resources usually contains sudden and unpredictable changes. Therefore, maintaining grid operations has become a challenging task, especially with high percentage of renewable energy penetration. A smart grid is different from a traditional power system in that it allows incorporation of intelligent features and functions, e.g., meter reading, adaptive demand response, integration of distributed energy sources, substation automation, etc. On the other hand, the proper operation of smart grid requires many different smart grid applications functioning in an organized manner. Functions of all these smart grid applications are made possible by two-way communication technologies and networks. Any uncertainty or failure of the communication system will affect the operation of the power system. To analyze electric power grid operations, it is necessary to take into account the integrated communication system. To protect end-use customers’ privacy, a reliable and secure communication network is necessary. Applying cyber security technologies, such as encryption methods, to prevent adversary attacks can protect customers’ privacy and allow the smart grid to operate reliably. Nonetheless, implementing encryption methods require extra software and hardware which increase complexity of the system. In addition, the processing of encryption/decrption also extends the system latency. Especially, by using strict cyber security standards, the operation of smart grid application may be negated. However, some smart grid applications have strict demands on fast operation speed. Therefore, it is necessary to analyze the limitation of using encryption methods on the smart grid operation.

Evacuation processes can be evaluated using different simulation models. However, recently, microscopic simulation models have become a more popular tool for this purpose. The objectives of this study are to model multiple evacuation scenarios and to compare the INTEGRATION microscopic traffic simulation model against the MATSim mesoscopic model. Given that the demand was the same for both models, the comparison was achieved based on three indicators: estimated evacuation time, average trip duration, and average trip distance. The results show that the estimated evacuation times in both models are close to each other since the Origin-Destination input file has a long tail distribution and so the majority of the evacuation time is associated when travelers evacuate and not the actual evacuation times. However, the evaluation also shows a considerable difference between the two models in the average trip duration. The average trip duration using INTEGRATION increases with increasing traffic demand levels and decreasing roadway capacity. On the other hand, the average trip duration using MATSim decreases with increasing traffic demand and decreasing the roadway capacity. Finally, the average trip distance values were significantly different in both models. The conclusion showed that the INTEGRATION model is more realistic than the MATSim model for evacuation purposes. The study concludes that despite the large execution times of a microscopic traffic simulation, the use of microsimulation is a worthwhile investment. / Master of Science / In recent decades, evacuation processes have become very valuable to protect people’s lives during disasters. Traffic engineers have developed different computer program tools to enhance the evacuation process. These tools can be categorized into three different groups: microscopic, macroscopic, and mesoscopic simulations. However, microscopic simulation tools have recently become more popular. The objectives of this thesis are to model multi-evacuation scenarios and to compare the INTEGRATION microscopic traffic simulation tool against the MATSim mesoscopic tool, given that the demand was the same for both tools. The demand describes the total number of vehicles that need to be evacuated. The tools were compared based on three indicators: estimated evacuation time, average trip duration, and average trip distance. The results show that, since the demand file has a large number of trips, the estimated evacuation times for both tools are similar. The average trip duration is generally computed by dividing the total travel time of all vehicles that need to finish their trips by the total number of vehicles. The results show that the average trip durations for the tools are different. The average trip duration using INTEGRATION increases with a decrease in the network capacity (number of vehicles within a specific distance). In contrast, the average trip duration using MATSim decreases with a decreasing network capacity. The average trip distance is computed by dividing the total travel distance by the total number of vehicles. The average trip distance values were significantly different for these tools. The results show that the INTEGRATION tool is more realistic than the MATSim tool and that it is able to capture the congestion effects in the network.

Die vorliegende Arbeit befasst sich mit verschiedenen Textildruckverfahren und der terminologischen Untersuchung dieses Fachbereichs im Bereich Print-on-Demand. Die Untersuchung wurde am Beispiel der bei der sprd.net AG angewendeten Verfahren für die Sprachen Deutsch und Französisch angewendet.

The research study focused on assessing the potential risk of failing to maintain water supply in the Rand Water area. The study analysed all factors and areas that contributes to water supply in the Rand Water area; this included municipalities supplied by Rand Water, the Department of Water Affairs and other factors that directly affect Rand Water supply such as population growth, increased urbanisation and acid mine drainage. The objectives of the study were: (a) is to determine the potential risk of failing to maintain supply in the Rand Water supply area, in other words, the likeliness of water not being supplied adequately to customers. (b) generate timely and credible information to determine the understanding, awareness, and acknowledgement by the sampled management group of the existence of the potential water supply risk in the Rand Water supply area. This will be done through a quantitative study. The research study approach that was utilized was a quantitative methodology; this approach included the distribution of questionnaires to all relevant stakeholders in the Rand Water supply area. To address the problems that are highlighted in the problem statement and achieve the objectives of the study these answered questionnaires were then sent to a Statistical consultant at North-West University‟s Potchefstroom Campus, to be analysed using an SPSS Version 21 statistical program. The questionnaires were divided into the three big municipal customers, these municipalities combined takes a total of 74.35% of Rand Water supply; these are Johannesburg Water which is part of the City of Johannesburg Metropolitan Municipality, Ekurhuleni Metropolitan Municipality, Tshwane Metropolitan Municipality and other small municipalities and the Department of Water Affairs‟ officials. Many previous studies also were assessed to be able to help this study establish the seriousness of the water challenge, the amount of work that has already been done, factors contributing to the problem and finally, measures that can be put in place to address the problem. The results that were obtained for this study provided many relationships between this study‟s selected variables and also highlighted the need to put certain strategies in place to be able to control the growing demand for water in the Rand Water system. The name of the Department of Water Affairs has changed many times over the year. It used to be called DWAF (Department of Water Affairs and Forestry, then DWEA (Department of Water and Environmental Affairs, then DWA (Department of Water Affairs) and it has recently been changed to DWS (Department of Water and Sanitation. For the purposes of this study this department will be called DWA (The Department of Water Affairs) The results were very relevant as most of the relationships were found between variables that are practically supposed to be related in order for the problem to be dealt with fruitfully. From these results it could be concluded that the risk of failing to maintain water supply in the Rand Water supply area does exist, if certain factors were allowed to trend the way they‟ve been trending without measures in place to counteract them. It could also be concluded that certain measures have been initiated to deal with the problem; this included water demand management. Results indicated that collective efforts from all stakeholders in the Rand Water supply area will be crucial in addressing the water supply challenge and avoid future failure to supply. To close the gap between previous research studies and this research study recommendations were made. Areas of future research were also highlighted; these are areas that can add value in providing valued information to help the challenge of water shortage in the Rand Water supply area. This area of future research studies will also be crucial in identifying other external factors that were not highlighted in the study but contribute to the problem. This area of future research studies will also help when implementing turnaround strategies to avoid the risk of failing to maintain supply in the Rand Water area as it will be able to highlight a different strategy that deals with the problem holistically. / MBA, North-West University, Potchefstroom Campus, 2015

The research study focused on assessing the potential risk of failing to maintain water supply in the Rand Water area. The study analysed all factors and areas that contributes to water supply in the Rand Water area; this included municipalities supplied by Rand Water, the Department of Water Affairs and other factors that directly affect Rand Water supply such as population growth, increased urbanisation and acid mine drainage. The objectives of the study were: (a) is to determine the potential risk of failing to maintain supply in the Rand Water supply area, in other words, the likeliness of water not being supplied adequately to customers. (b) generate timely and credible information to determine the understanding, awareness, and acknowledgement by the sampled management group of the existence of the potential water supply risk in the Rand Water supply area. This will be done through a quantitative study. The research study approach that was utilized was a quantitative methodology; this approach included the distribution of questionnaires to all relevant stakeholders in the Rand Water supply area. To address the problems that are highlighted in the problem statement and achieve the objectives of the study these answered questionnaires were then sent to a Statistical consultant at North-West University‟s Potchefstroom Campus, to be analysed using an SPSS Version 21 statistical program. The questionnaires were divided into the three big municipal customers, these municipalities combined takes a total of 74.35% of Rand Water supply; these are Johannesburg Water which is part of the City of Johannesburg Metropolitan Municipality, Ekurhuleni Metropolitan Municipality, Tshwane Metropolitan Municipality and other small municipalities and the Department of Water Affairs‟ officials. Many previous studies also were assessed to be able to help this study establish the seriousness of the water challenge, the amount of work that has already been done, factors contributing to the problem and finally, measures that can be put in place to address the problem. The results that were obtained for this study provided many relationships between this study‟s selected variables and also highlighted the need to put certain strategies in place to be able to control the growing demand for water in the Rand Water system. The name of the Department of Water Affairs has changed many times over the year. It used to be called DWAF (Department of Water Affairs and Forestry, then DWEA (Department of Water and Environmental Affairs, then DWA (Department of Water Affairs) and it has recently been changed to DWS (Department of Water and Sanitation. For the purposes of this study this department will be called DWA (The Department of Water Affairs) The results were very relevant as most of the relationships were found between variables that are practically supposed to be related in order for the problem to be dealt with fruitfully. From these results it could be concluded that the risk of failing to maintain water supply in the Rand Water supply area does exist, if certain factors were allowed to trend the way they‟ve been trending without measures in place to counteract them. It could also be concluded that certain measures have been initiated to deal with the problem; this included water demand management. Results indicated that collective efforts from all stakeholders in the Rand Water supply area will be crucial in addressing the water supply challenge and avoid future failure to supply. To close the gap between previous research studies and this research study recommendations were made. Areas of future research were also highlighted; these are areas that can add value in providing valued information to help the challenge of water shortage in the Rand Water supply area. This area of future research studies will also be crucial in identifying other external factors that were not highlighted in the study but contribute to the problem. This area of future research studies will also help when implementing turnaround strategies to avoid the risk of failing to maintain supply in the Rand Water area as it will be able to highlight a different strategy that deals with the problem holistically. / MBA, North-West University, Potchefstroom Campus, 2015

Peak demand is an issue in power supply system when demand exceeds the available capacity. Continuous growth in peak demand increases the risk of power failures, and increases the marginal cost of supply. The contribution of the residential sector to the system peak is quite substantial and has been a subject of discussion internationally. For example, a study done in New Zealand in 2007 attributed about half of system peak load to the residential sector. International research has attributed a significant influence of human behaviour on households energy use. “Demand Response” is a demand side management tool aimed at achieving peak energy demand reduction by eliciting behaviour change. It encompasses energy needs analysis, information provision to customers, behaviour induction, smart metering, and new signalling and feedback concepts. Demand response is far advanced in the industrial and commercial demand sectors. In the residential sector, information barriers and a lack of proper understanding of consumers’ behaviour have impeded the development of effective response strategies and new enabling technologies in the sector. To date, efforts to understanding residential sector behaviour for the purpose of peak demand analysis has been based on pricing mechanism. However, not much is known about the significance of other factors in influencing household customers’ peak electricity demand behaviour. There is a tremendous amount of data that can be analyzed and fed back to the user to influence behaviour. These may include information about energy shortages, supply security and environmental concerns during the peak hours. This research is intended to begin the process of understanding the importance of some of these factors in the arena of peak energy consumption behaviour. Using stated preference survey and focus group discussions, information about household customers’ energy use activities during winter morning and evening peak hours was collected. Data about how customers would modify their usage behaviour when they receive enhanced supply constraint information was also collected. The thesis further explores households’ customer demand response motivation with respect to three factors: cost (price), environment (CO2-intensity) and security (risk of black-outs). Householders were first informed about the relationship between these factors and peak demand. Their responses were analyzed as multi-mode motivation to energy use behaviour change. Overall, the findings suggest that, household customers would be willing to reduce their peak electricity demand when they are given clear and enhanced information. In terms of motivation to reduce demand the results show customers response to the security factor to be on par with the price factor. The Environmental factor also produced a strong response; nearly two-thirds of that of price or security. A generic modelling methodology was developed to estimate the impact of households’ activity demand response on the load curve of the utility using a combination of published literature reviews and resources, and own research work. This modelling methodology was applied in a case study in Halswell, a small neighbourhood in Christchurch, New Zealand, with approximately 400 households. The results show that a program to develop the necessary technology and provide credible information and understandable signals about risks and consequences of peak demand could provide up to about 13% voluntary demand reduction during the morning peak hours and 8% during the evening peak hours.

The dynamics of demand for energy goods such as gasoline are complicated by investment decisions and behavioral habits. Both types of complication can be captured by a habits model, in which past consumption enters into an agent's current utility function. If the agent is forward-looking, or 'rational', then habits imply his consumption of the habit-forming good will be sensitive to his expectation of future market conditions, in particular future prices. This sensitivity implies, in turn, that demand and price elasticity will depend upon price volatility, and that the agent will respond differently to different types of price changes. Price elasticity measured over the mixture of price changes that occur in a given market will therefore underestimate the power of policy instruments that act through permanent or long-run price changes. This thesis examines the implications of rational habits on demand behavior in a multi-good setting, drawing motivation from and considering applications to gasoline demand. Chapter 1 introduces the theory of rational habits, examines a simple perfect-foresight model, and uses microeconometric techniques to look at an application to U.S. gasoline demand. Chapter 2 builds a theory model in which agents have rational habits and future prices are uncertain. The implications of this model are then utilized in Chapter 3, which uses macro-type econometric techniques to test for rational habits in international gasoline demand. The empirical evidence suggests that rational habits may indeed shape demand for gasoline and that traditionally-measured price elasticity should not be used to project consumers' responses to policy interventions.

Nesta tese, consideramos que plataformas online configuram instrumentos de comunicação e difusão que muito contribuem para a propagação de discursos formadores de uma nova onda feminista. Analisamos como artistas e ativistas do eixo geopolítico Sul-sul produzem e difundem seus materiais em plataformas on demand, em específico o YouTube. O presente projeto propõe um olhar mais apurado sobre as novas estratégias poéticas na montagem audiovisual, presentes nestas plataformas digitais. / In this thesis, we consider that online platforms configure communication and dissemination tools that greatly contribute to the propagation of discourses which form a new feminist wave. We analyze how South-South geopolitical artists and activists produce and disseminate their materials using on demand platforms, specifically YouTube. This project proposes a more accurate look at the new poetic strategies in the audiovisual editing, present in these digital platforms