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An adaptive mesh refinement algorithm for shallow water equations is presented. The algorithm uses upwind scheme that is Godunov type and which approximately solves the Riemann problem using Roe's technique. A highly accurate solution is achieved by using the adaptive mesh refinement technique of Berger and Oliger for mesh refinement algorithm. The numerical method is second-order accurate and approximately max-min preserving by using van Leer limited-slope technique. One-dimensional nesting algorithm has been implemented successfully. Numerical results on a test problem verify the second order accuracy of the algorithm. The nested grid results yield the equivalent solution to that of the corresponding fine grid solution.

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Communications-based train control (CBTC) aims to improve headways in the railway systems while maintaining or even improving safety. By means of the CBTC systems, the exact position of a train is known more accurately than the traditional signalling systems. It is a continuous, automatic train control system utilizing high-resolution train location determination, independent from track circuits. The system makes use of the telecommunications between the train and track equipment for the traffic management and infrastructure control. Roslagsbanan is a narrow gauge urban railway system that connects Stockholm with the northern suburbs of the city and despite its age and limited capacity, it is one of the most used railways in Sweden. From the beginning, the entire track consisted of single-tracks where the trains had to wait for each other on special meeting tracks. Αn expansion plan is now underway and the authorities are building approximately 22 km of double-track where the trains will be able to meet. All work along the Roslagsbanan aims to increase capacity, safety and accessibility. With more double-tracks and an updated signal system, the risk of traffic disruptions will be reduced and it is possible to have more frequent traffic in the future. This master’s thesis investigates a CBTC implementation in Roslagsbanan according to the current expansion plan and comparisons are conducted between the current capacity of the ATC system. A simulation model is developed that calculates the train’s safe braking curve and safe braking distance and two case studies are examined. The first one: Calculation of the capacity of the train routes and examination a capacity increase by a minimum 20% during rush hour, taking into consideration the current expansion plan in double-tracks. The second one: Calculation of the capacity of the train routes considering double-tracks the entire route. In this way, differences could be seen between the traffic density with single and double-tracks. Several insights were gained during the realization of this project and as well as timetables have been created to visualize the findings of this thesis. The timetable’s regularity time is decreased to a significant degree and more frequent traffic can be accommodated. Furthermore, the capacity is definitely affected by the track/infrastructure design however, it is questionable whether this increase in capacity outweighs the economic factor of expanding the entire route to double-tracks. / Kommunikationsbaserad tågkontroll (CBTC) syftar till att förbättra framsteg i järnvägssystemen samtidigt som säkerheten bibehålls eller till och med förbättras. Med hjälp av CBTC-systemen är ett tågs exakta position känd mer exakt än de traditionella signalsystemen. Det är ett kontinuerligt, automatiskt tågkontrollsystem som använder högupplöst tåglägesbestämning, oberoende av spårledning. Systemet använder telekommunikation mellan tåg och spårutrustning för trafikledning och infrastrukturkontroll. Roslagsbanan är ett smalspårigt stadsjärnvägssystem som förbinder Stockholm med stadens norra förorter och trots sin ålder och begränsade kapacitet är det en av de mest använda järnvägarna i Sverige. Från början bestod hela spåret av enkelspår där tågen fick vänta på varandra på speciella mötesstationer. Ett utvecklingsprogram pågår nu och myndigheterna bygger cirka 22 km dubbelspår där tågen kommer att kunna mötas. Allt arbete längs Roslagsbanan syftar till att öka kapacitet, säkerhet och tillgänglighet. Med fler dubbelspår och ett uppdaterat signalsystem minskar risken för trafikstörningar och det är möjligt att ha mer frekvent trafik i framtiden. Detta examensarbete undersöker ett CBTC-genomförande i Roslagsbanan enligt den nuvarande expansionsplanen och jämförelser görs med ATC-systemets nuvarande kapacitet. En simuleringsmodell har utvecklats som beräknar tågets säkra bromskurva och säkra bromssträcka och två fallstudier undersöks. Den första: Beräkning av tåglinjernas kapacitet och undersökning av en kapacitetsökning med minst 20% under rusningstid med hänsyn till den nuvarande expansionsplanen i dubbelspår. Den andra: Beräkning av tåglinjernas kapacitet med tanke på dubbelspår hela rutten. På detta sätt kunde skillnader ses mellan trafiktätheten med enkel- och dubbelspår. Flera insikter gjordes under genomförandet av detta projekt och tidtabeller har skapats för att visualisera resultaten av denna avhandling. Tiden mellan tågen minskas i betydande grad och mer frekvent trafik kan tillgodoses. Dessutom påverkas kapaciteten definitivt av ban-/infrastrukturutformningen, men det är tveksamt om denna kapacitetsökning uppväger den ekonomiska faktorn att utöka hela rutten till dubbelspår.

As 4/4 block scheduling was implemented in North Carolina, many public schools offered staff development to help teachers make the transition from a six- or seven- period school schedule, but little is known about the staff development provided. The purposes of this study were to determine the Stages of Concern of North Carolina public school teachers related to 4/4 block scheduling, their perceived professional development needs, and the relationships among their Stages of Concern, professional development needs, and selected characteristics. By calling each school district's central office, the researcher determined that 248 North Carolina high schools had implemented 4/4 block scheduling as of fall 1998. A list was developed of 73 schools that implemented block scheduling in the fall of 1996, 1997, and 1998. From this list, five schools were randomly selected for each of the three years, resulting in a sample of 15 schools. At each school, five teachers were selected from each of three teaching areas: academic, workforce development, and special subjects. Thus, of the1086 teachers employed at the 15 participating schools, 225 teachers were included in the sample. The questionnaire for this study contained three parts: (a) the Hall and Loucks (1979) Stages of Concern questionnaire, (b) a professional development needs section, and (c) a teacher characteristics section. Results of the study indicated that the teachers were concerned about the success of students in the classroom and the impact of 4/4 block scheduling on their students. Consequence was the peak Stage of Concern for the largest percentage of responders, and collaboration was the peak for the second-largest percentage. Teachers with less experience had higher informational concerns than their peers with more teaching experience. On four of the nine professional development needs, more recent adopters of 4/4 block scheduling indicated significantly less need for professional development than those whose schools adopted this schedule in previous years. Thus, as teachers became more experienced with 4/4 block scheduling, they may have had problems that were unforeseen when this schedule was initially adopted. Implications for practice and further research based on the results of the study were suggested. / Ph. D.