Future Interests

I denna rapport utreds olika metoder för att kunna reglera vattennivån i vattenkraftverket Avesta Lillfors i Dalarna. Två kraftverk ligger endast 900 m uppströms och detta gör att svarstiderna blir korta och regleringen blir lätt nervös. Att använda sig av vattennivåreglering i ett kraftverk för-enklar dess styrning då anpassning till inflödet sker automatiskt. En flödestabell har tagits fram genom mätningar i turbinen, med hjälp av Winter-Kennedy-metoden. Denna tabell används för att kunna fram-koppla regulatorn och därmed dämpa stora variationer i inflödet. Dessu-tom har en modell av älven skapats och testats med en återkopplad PID-regulator. Utefter dessa tester har lämpliga parametrar tagits fram, som ger önskad stabilitet, noggrannhet och snabbhet. Simuleringar har även gjorts med reglermetoden Fuzzy logic.This report evaluates different methods to create a stable regulation of the water level in the hydro power plant Avesta Lillfors, in county Dalar-na. Another pair of plants are located just 900 m up the stream, which is why the regulation has to act fast. If the water level can be regulated and automatically adjust to the incoming flow, it facilitates the control of the plant. A flow chart is created from measurements in the turbine, using the Win-ter-Kennedy method. The results are used for feedforward control. A PID-regulator with feedback is also simulated in a model of the river. This helps finding the parameters that provide a stable, accurate and fast regu-lation. Fuzzy logic control has also been simulated

Lewis M. Simes as Teacher

A Tribute to Lewis M. Sime

Geology of the Snap Lake kimberlite intrusion, Northwest Territories, Canada: field observations and their interpretation

The Cambrian (523 Ma) Snap Lake hypabyssal kimberlite intrusion, Northwest Territories, Canada, is a complex segmented diamond-bearing ore-body. Detailed geological investigations suggest that the kimberlite is a multi-phase intrusion with at least four magmatic lithofacies. In particular, olivine-rich (ORK) and olivine-poor (OPK) varieties of hypabyssal kimberlite have been identified. Key observations are that the olivine-rich lithofacieshas a strong tendency to be located where the intrusion is thickest and that there is a good correlation between intrusion thickness, olivine crystal size and crystal content. Heterogeneities in the lithofacies are attributed to variations in intrusion thickness and structural complexities. The geometry and distribution of lithofacies points to magmaticco-intrusion, and flow segregation driven by fundamental rheological differences between the two phases. We envisage that the low-viscosity OPK magma acted as a lubricant for the highly viscous ORK magma. The presenceof such low-viscosity, crystal-poor magmas may explain how crystal-laden kimberlite magmas (>60 vol.%) are able to reach the surface during kimberlite eruptions. We also document the absence of crystal settling and the development of an unusual subvertical fabric of elongate olivine crystals, which are explained by rapid degassing-induced quench crystallization of the magmas during and after intrusio

Viewpoints of elementary principals and their teachers concerning teachers' meetings as they are conducted within schools in five Massachusetts towns

Thesis (Ed.M.)--Boston Universit

Line strength variations in beta Cephei

The line strength variations of the resonance line of C IV (1550A, 2s 2S - 2P) observed by OAO-2 were confirmed by IUE observations. In addition, the NV resonance line (1204A, 2s 2S - 2P), the Si III line (1206A, 3p 1P-1D, multiplet 11) and the Si IV resonance line (1395A, 3s 2S - 2P) all vary in line strength essentially in phase with the C IV variation. The (preliminary) period of the variation is 6.02/12.04 days