The Intelligent Transportation System (ITS) is a cooperative system that relies on reliable and robust communication schemes among vehicles and between vehicles and their surroundings. The main objective of the ITS is to ensure the safety of vehicle drivers and pedestrians. It provides an efficient and reliable transportation system that enhances traffic management, reduces congestion time, enables smooth traffic re-routing, and avoids economic losses. An essential part of the ITS is the Vehicular Ad hoc Network (VANET). VANET enables the setup of Vehicle-to-Vehicle (V2V) as well as Vehicle-to-Infrastructure (V2I) communication platforms: the two key components in the ITS. The de-facto standard used in wireless V2V and V2I communication applications is the Dedicated Short Range Communication (DSRC). The protocol that defines the specifications for the Medium Access Control (MAC) layer and the physical layer in the DSRC is the IEEE 802.11p protocol. The IEEE 802.11p protocol and its Enhanced Distributed Channel Access (EDCA) mechanism are the main focus of this thesis. Our main objective is to develop new IEEE 802.11p-based protocol for V2V and V2I communication systems, to improve the performance of safety-related applications. These applications are of paramount importance in ITS, because their goal is to decrease the rate of vehicle collisions, and hence reduce the enormous costs associated with them. In fact, large percentage of vehicle collisions can be easily avoided with the exchange of relevant information between vehicles and the Road Side Units (RSUs) installed on the sides of the roads. In this thesis, we propose various enhancements to the IEEE 802.11p protocol to improve its performance by lowering the average end-to-end delay and increasing the average network throughput. We introduce multiple adaptive algorithms to promote the QoS support across all the Access Categories (AC) in IEEE 802.11p. We propose two adaptive backoff algorithms and two algorithms that adaptively change the values of the Arbitrary Inter-Frame Space (AIFS). Then we extend our model to be applied in a large-scale vehicular network. In this context, a multi-layer cluster-based architecture is adopted, and two new distributed time synchronization mechanisms are developed.

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In the last twenty years, Google had a tremendous growth, from a small project of two PhD students to one of the most valuable companies on the globe. This growth is characterised by the versatile of the company, next to its search engine, Google explored many different value chains along the way. In this study, the value grid model is used to examine their movements. It can be stated that Google used, and uses, the paths/dimension as implied by Pil and Holweg (2006) to explore new opportunity and demand. The main reason why Google is able to do so is because of its board and management, who are innovative, and open-minded. Next to the top management is the appearance of Google in many different sectors and value chains a reason of their growth. The variety in businesses allows them to create a “Google experience”, and thus a competitive advantage in comparison with their main competitors who do not have this ability.

Wireless sensor networks (WSNs) have a tremendous potential to improve the efficiencyof many systems, for instance, in building automation and process control.Unfortunately, the current technology does not offer guaranteed energy efficiencyand reliability for closed-loop stability. The main contribution of this thesis is toprovide a modeling, analysis, and design framework for WSN protocols used in controlapplications. The protocols are designed to minimize the energy consumption ofthe network, while meeting reliability and delay requirements from the applicationlayer. The design relies on the analytical modeling of the protocol behavior.First, modeling of the slotted random access scheme of the IEEE 802.15.4medium access control (MAC) is investigated. For this protocol, which is commonlyemployed in WSN applications, a Markov chain model is used to derive theanalytical expressions of reliability, delay, and energy consumption. By using thismodel, an adaptive IEEE 802.15.4 MAC protocol is proposed. The protocol designis based on a constrained optimization problem where the objective function is theenergy consumption of the network, subject to constraints on reliability and packetdelay. The protocol is implemented and experimentally evaluated on a test-bed. Experimentalresults show that the proposed algorithm satisfies reliability and delayrequirements while ensuring a longer lifetime of the network under both stationaryand transient network conditions.Second, modeling and analysis of a hybrid IEEE 802.15.4 MAC combining theadvantages of a random access with contention with a time division multiple access(TDMA) without contention are presented. A Markov chain is used to model thestochastic behavior of random access and the deterministic behavior of TDMA.The model is validated by both theoretical analysis and Monte Carlo simulations.Using this new model, the network performance in terms of reliability, averagepacket delay, average queueing delay, and throughput is evaluated. It is shown thatthe probability density function of the number of received packets per superframefollows a Poisson distribution. Furthermore, it is determined under which conditionsthe time slot allocation mechanism of the IEEE 802.15.4 MAC is stable.Third, a new protocol for control applications, denoted Breath, is proposedwhere sensor nodes transmit information via multi-hop routing to a sink node. Theprotocol is based on the modeling of randomized routing, MAC, and duty-cycling.Analytical and experimental results show that Breath meets reliability and delayrequirements while exhibiting a nearly uniform distribution of the work load. TheBreath protocol has been implemented and experimentally evaluated on a test-bed.Finally, it is shown how the proposed WSN protocols can be used in controlapplications. A co-design between communication and control application layers isstudied by considering a constrained optimization problem, for which the objectivefunction is the energy consumption of the network and the constraints are thereliability and delay derived from the control cost. It is shown that the optimaltraffic load when either the communication throughput or control cost are optimizedis similar. / QC 20110217

This paper presents a model and analysis of a synchronous tandem flow line that produces different part types on unreliable machines. The machines operate according to a static priority rule, operating on the highest priority part whenever possible, and operating on lower priority parts only when unable to produce those with higher priorities. We develop a new decomposition method to analyze the behavior of the manufacturing system by decomposing the long production line into small analytically tractable components. As a first step in modeling a production line with more than one part type, we restrict ourselves to the case where there are two part types. Detailed modeling and derivations are presented with a small two-part-type production line that consists of two processing machines and two demand machines. Then, a generalized longer flow line is analyzed. Furthermore, estimates for performance measures, such as average buffer levels and production rates, are presented and compared to extensive discrete event simulation. The quantitative behavior of the two-part type processing line under different demand scenarios is also provided. / Singapore-MIT Alliance (SMA)

Experience feedback from accidents is important for preventive work in companies, authorities and other organisations. This thesis focused on experience feedback from accidents that take place in everyday life, in our neighbourhoods, in our workplaces, in our schools, in traffic and transportation. Essay I is an overview of the literature on learning from accidents and incidents. The focus in this essay is on literature that evaluates the effectiveness and usefulness of different methods in accident investigations. Conclusions drawn from this literature review are that the dissemination of results and knowledge from accident investigations must be improved, and experience feedback systems should be integrated into overall systems of risk management. Essay II is based on an evaluation of the investigation board for workplace accidents (HAKO) that was carried out on commission of the Swedish Work Environment Authority. It was concluded that the accident reports published by HAKO had a high qualitative level but the dissemination of results from the investigations was weak. Essay III investigates twenty-eight supervision cases from eleven Swedish local Environment and Health Administrations. The overall goal of the study was to find out how, and to what extent, experience feedback occurs in Swedish municipalities. Two major problems relevant for the experience feedback have been found; namely that the inspectors do not have enough guidance on how to interpret the law and that they would like more information on what happens to legal cases that they have handed over to the public prosecutors and the police. Essay IV is a document study of incident reports from two municipal fire and rescue services. The overall purpose of this study was to investigate if information from the rescue services could be used to improve experience feedback in sectors where it is weak or non-existent. In the 1120 incident reports that were studied, we found 217 proposals for improvement but these proposals were not used for experience feedback. It is concluded that the reports contain valuable information but this information is not used to prevent future accidents. Essay V investigates experience feedback in Swedish authorities working with accident prevention. The essay is based on two interview studies. In the first study, 21 Swedish authorities participated, and several of these authorities seem to have a functioning experience feedback despite the lack of systematic routines and methods. Yet, only four of the 21 authorities actually handle the whole experience feedback process. These four have at least one common denominator; they have an experience feedback that is turning more inwards than outwards. The second study was a follow-up study of some of the results from the first study, concerning the dissemination of results from experience feedback. / QC 20101209

Grinding of clinker is the last and most energy-consuming stage of the cement manufacturing process, drawing on average 40% of the total energy required to produce one ton of cement. During this stage, the clinker particles are substantially reduced in size to generate a certain level of fineness as it has a direct influence on such performance characteristics of the final product as rate of hydration, water demand, strength development, and other. The grinding objectives tying together the energy and fineness requirements were formulated based on a review of the state of the art of clinker grinding and numerical simulation employing the Markov chain theory. The literature survey revealed that not only the specific surface of the final product, but also the shape of its particle size distribution (PSD) is responsible for the cement performance characteristics. While it is feasible to engineer the desired PSD in the laboratory, the process-specific recommendations on how to generate the desired PSD in the industrial mill are not available. Based on a population balance principle and stochastic representation of the particle movement within the grinding system, the Markov chain model for the circuit consisting of a tube ball mill and a high efficiency separator was introduced through the matrices of grinding and classification. The grinding matrix was calculated using the selection and breakage functions, whereas the classification matrix was defined from the Tromp curve of the separator. The results of field experiments carried out at a pilot cement plant were used to identify the model's parameters. The retrospective process data pertaining to the operation of the pilot grinding circuit was employed to validate the model and define the process constraints. Through numerical simulation, the relationships between the controlled (fresh feed rate; separator cut size) and observed (fineness characteristics of cement; production rate; specific energy consumption) parameters of the circuit were defined. The analysis of the simulation results allowed formulation of the process control procedures with the objectives of decreasing the specific energy consumption of the mill, maintaining the targeted specific surface area of the final product, and governing the shape of its PSD.

<p>The subject of this licentiate thesis is experience feedback from accidents and incidents. The thesis aims to contribute to an understanding of how the learning processes within organizations, companies and authorities could be improved.</p><p><i>Essay I </i>(written together with Sven Ove Hansson) reports on an evaluation carried out in 2004 by the Swedish Work Environment Authority’s Accident Investigation Board, called HAKO (Haverikommissionen). An important outcome of this evaluation shows that HAKO have not been able to manage the dissemination of their written reports, which is unfortunate, since the reports are thoroughly written.</p><p><i>Essay II</i> (written with Sven Ove Hansson and Carl Rollenhagen) is an overview of the literature on learning from accidents and incidents. The focus in this essay is on literature that evaluates the effectiveness and usefulness of different methods in accident investigations. The conclusions drawn from this literature review are that the dissemination of results and knowledge from accident investigations must be improved, and experience feedback systems should be integrated into overall systems of risk management.</p><p>The starting point for<i> Essay III </i>was an empirical study conducted in 2005/2006. Twenty-eight supervision cases from eleven local Environment and Health Administrations in Sweden were examined. The overall goal of the study was to find out how, and to what extent, experience feedback occurs between different municipal authorities. Two major problems affecting experience feedback have been found; namely, that the inspectors do not have enough guidance on how to interpret the law, and that they would like more information on what happens to legal cases they have reported to public prosecutors and police.</p>

The aim of this work was to investigate if interesting patterns could be found in time series radar data that had been discretized by the algorithm ARAVQ into symbolic representations and if the ARAVQ thus might be suitable for use in the radar domain. An experimental study was performed where the ARAVQ was used to create symbolic representations of data sets with radar data. Two experiments were carried out that used a Markov model to calculate probabilities used for discovering potentially interesting patterns. Some of the most interesting patterns were then investigated further. Results have shown that the ARAVQ was able to create accurate representations for several time series and that it was possible to discover patterns that were interesting and represented higher level concepts. However, the results also showed that the ARAVQ was not able to create accurate representations for some of the time series.

The objective of this thesis is to review the two popular mathematical models of the financialderivatives market. The models are the classical Black–Scholes–Merton and the Continuoustime Markov chain (CTMC) model. We study the CTMC model which is illustrated by themathematician Ragnar Norberg. The thesis demonstrates how the fundamental results ofFinancial Engineering work in both models.The construction of the main financial market components and the approach used for pricingthe contingent claims were considered in order to review the two models. In addition, the stepsused in solving the first–order partial differential equations in both models are explained.The main similarity between the models are that the financial market components are thesame. Their contingent claim is similar and the driving processes for both models utilizeMarkov property.One of the differences observed is that the driving process in the BSM model is the Brownianmotion and Markov chain in the CTMC model.We believe that the thesis can motivate other students and researchers to do a deeper andadvanced comparative study between the two models.