· · · Institutional Repository

As CMOS technology is scaling down, the effect of voltage drop in power distribution network is becoming more prominent. Such voltage drops on power lines in a clock network introduces significant amount of skew, thereby degrading the signal integrity. With rising power consumption and decreasing supply voltages, the upply current will increase in future devices. The IR drops can be reduced by using large wires which negatively impacts the global routing. Thus to provide proper supply voltages, on chip DC-DC converters are designed. The purpose of this project is to design an on-chip DC-DC converter targeted for System on Chip (SOC). In this thesis switched capacitor up converter and differential based voltage down converter is designed in UMC90. A new design for differential based voltage down converter is described to increase the efficiency of the converter. The specifications of the converters are defined by the system requirements. After meting the system requirements, layout of both converters is designed. The converters designed have high efficiency and small layout area.

Albania has the following major sea ports: Durrës, Vlora, Sarandë and Shëngjin. The port of Durrës has the biggest share in the volume of import/export in Albania, nearly 75%. Due to current development rates, limited possibilities for expansion and pollution in the city because of its vicinity to the port, projects are identified to construct a new port which will better meet increasing needs and demands. This gives a reason to do research on the possibilities of constructing port facilities at an alternative location. This new ‘port’ is designed in the Durrës area. To design a new port, information is needed about future trade and traffic anticipated in the future. An effort was made to make some forecasts in order to render this report more realistic. The produced forecasts are bases on a combination of past data extrapolation, trade and traffic trends as well as insight in the situation of Albania and hinterland connections. The master plan duration, which will be 25 years (2010-2035), is divided into three periods. Three different growth scenarios were taken into account. This report has been based on the medium growth scenario (4.3%, 3.8% and 3.1 % increase in the total trade of Albania in tons for the three time periods respectively). Assuming a medium growth scenario 1,807,000 tons of dry bulk will be handled in Porto Romano in 2035, 774,000 tons liquid bulk, 1,033,000 tons general cargo and 215,111 TEUs. When Romano Port starts functioning, it is immediately able to accommodate container vessels up to 45,000 dwt. For dry bulk it is assumed that the port should be able to accommodate vessels up to 40,000 dwt. The General Cargo vessels which currently enter the port of Durrës have an average size of 4,000 dwt. Although in general the size of General Cargo vessels remains relative small the average ship is expected to increase up to 10,000 dwt in 2035, with a maximum of 15,000 dwt. The maximum ship size for the liquid bulk terminal is assumed at 25,000 dwt. Taking into account the above forecasts, the future needs concerning terminal areas, berths and equipment were depicted. The container terminal will require a storage area of 440,000 m2 and a berth length of 466 meter. Dry bulk needs an area of 62,000 m2 and a berth length of 240 meter. General cargo will require a storage area of 84,000 m2 and a berth length of 543 meter. For the liquid bulk terminal, no additional berth is required. Ten alternatives were generated based on the future needs above. Three of them were discussed in more detail. Several affecting parameters were taken into account like extensibility, tranquillity, manoeuvrability etc. The comparison among these alternatives was conducted with the help of a multi criteria analyses. The objectivity of this method was verified by doing several sensitivity checks. Finally it leads to a final optimum port layout. Two chapters are written about the breakwater and quay wall. After an analysis, where several breakwater types were discussed and a comparison between a caisson type and rubble mound breakwater was made, the rubble mound breakwater appeared to be the preferred solution. The breakwater armour layer is designed using a single layer of Accropode ll elements. A concrete unit is selected because the required weight of the armour units is substantially larger than the available 2 ton rock in the quarry nearby. For the quay wall, an open pile construction has been selected.

The aviation industry faces a number of challenges: it needs to produce safer, quieter and more efficient aircraft to meet the demands of the airlines and increasingly strict regulations. At the same time, engineers are becoming more scarce because the retirement age of the `baby-boom generation' is approaching. The department of Systems Engineering and Aircraft Design (SEAD) at Delft University of Technology has been developing methods to support aircraft design in order to meet these challenges for the future. One example of such a method is a generic aircraft modeling application, based on Knowledge-Based Engineering (KBE) techniques, called a Multi-Model Generator (MMG). The ICAD system was used in the past to create such an MMG. Unfortunately, this system has been discontinued. To continue research in this area, there was a need at the SEAD research group to develop a new MMG. The research group has selected GDL as a new KBE system. This system has been used to develop a new MMG. By starting the development work of the MMG as a clean-sheet design, opportunities existed to improve the modeling capabilities of the MMG. One such improvement is the modeling of fully curved wings in a practical way. A wing design procedure has been developed which is intuitive to aircraft designers, based on the planform shape of the wing and its dihedral and twist distribution. Airfoils of any shape can be used in any orientation on the wing. Accurate wing surfaces can be created for several aircraft configurations, including unconventional ones like the box wing and blended wing-body (BWB). The MMG also offers the capability to produce consistent analysis models. The foundations for aerodynamic and structural analysis modules have been laid. For this thesis work, an interface to the 3D panel code VSaero has been developed and tested for clean wings. Procedures to model wings with moveables and 'intersected' wings (e.g. wings with a pylon or fin attached to them) have been developed. With the new MMG, a large reduction in design time can be achieved. It enables the designer to obtain more knowledge about a design in an early phase of its development and eliminates repetitive, non-creative tasks. This is a step towards the further development of unconventional aircraft configurations, which have the potential to become the aircraft for the future.

The Amsterdam inner city with its medieval urban structure has always been a popular destination for tourists from all over the world. The canals, warehouses and the unconstrained lifestyle have become the trademark of the city. Especially this last property has become dominantly visible in the inner city structure, not only from an architectural but also from an economic point of view. Since the 60’s and 70’s the city’s sex and soft drugs policy attracted many tourists. These industries flourished and gave Amsterdam the characteristics of an ‘open air theme park’. This tendency initiated the debate about the use and image of the monumental inner city. This development forms for a large part the social context for the design of a commercial building in the centre of the Amsterdam inner city, located between the Kalverstraat and Rokin. The building should take position in this debate and make a statement about the future of the inner city. However, not only today’s social context plays a role in the development of this new building: At the end of the 19th century a hotel-restaurant designed by Pierre Cuypers embodied the grandeur and sophisticated lifestyle of Amsterdam which has partially disappeared. This ‘Hotel Polen’ was located at the exact same plot as our building location and formed a meeting point for artists, businessmen and politicians. The building consisted of a coffee shop at the Kalverstaat and a hotel and restaurant at the Rokin side, which overlooked the outfall the river Amstel. In 1977 the building was demolished because of a fire. With the project ‘1012’ the City of Amsterdam takes position in the above mentioned debate by proposing a decrease of the ordinary and an increase of the extraordinary with a representative strip through the inner city called the ‘red carpet’. This red carpet follows roughly the direction of the soon to be completed North/South line and should contain a concentration of higher end fashion and gastronomy. This building, located on the red carpet, should endorse the City’s ambitions in the form of a reinvention of the former ‘Hotel Polen’ and therefore it contains a varied and upscale mix of functions, including a hotel-restaurant. These functions are placed around a secluded public courtyard where one could escape the daily life bustle. Therewith it builds upon the typical Amsterdam courtyard tradition.

Increasing demand for oil in the near future implies the need for Enhanced Oil Recovery (EOR) methods to produce the remaining oil after primary and secondary production. Miscible gas injection has an excellent microscopic sweep efficiency; however due to density difference, high gas mobility and reservoir heterogeneity, the macroscopic sweep efficiency can be poor. The application of foam, which is a dispersion of a gas in a liquid phase with surfactant, greatly reduces the gas mobility. This minimizes gas override and gas channeling through high-permeability layers, thus increasing the macroscopic sweep efficiency. Fractional-flow theory provides key insights into one-dimensional miscible foam displacements. First-contact-miscible and multiple-contact-miscible displacement simulations show that foam is able to displace all the oil in the reservoir, and with sufficient grid resolution, the simulation converges towards the fractional-flow solution. Numerical dispersion introduced by the simulator affects the mobilities near the miscible front. In multiple-contact-miscible displacement simulations with insufficient grid resolution, numerical dispersion can cause loss of miscibility. Two-dimensional simulation shows that applying sufficient grid blocks to mitigate the effect of numerical dispersion for a multiple-contact-miscible displacement is, however, not feasible due to the enormous number of grid blocks and amount of time required to simulate each case. As a result, our 2D simulations of the multiple-contact-miscible case is more like an immiscible case than it is like a first-contact-miscible case. In both immiscible and multiple-contact-miscible displacements with insufficient grid resolution, there is a slowly advancing region of zero oil saturation as hydrocarbon is dissolved into injected CO2. Our results show that when oil has a detrimental effect on foam, as modelled in current simulators, it affects only immiscible foam displacements. In a miscible displacement there is only ever one nonaqueous phase present at any location; if it is "gas," there is no oil to destabilize foam; if it is "oil," there is no gas to generate foam. Thus, the effect of hydrocarbons on foam in miscible displacements is to destroy foam at the point where the simulator defines the nonaqueous phase to be "oil" instead of "gas." For immiscible displacements, foam sweep efficiency decreases greatly if the injected foam is not stable at the oil saturations encountered in the reservoir. Pressure variation causes in-homogeneity in densities and gas viscosity in the mixed zone for compressible CO2 not accounted for in Stone's model for gravity segregation. Nevertheless, Stone’s model is able to predict the segregation length for water and gas fairly accurate for first-contact-miscible, and certain multiple-contact-miscible displacement cases for co-injection and SAG injection, if one uses fluid properties from the middle of the mixed zone. For first-contact-miscible displacements, the steady state assumed in Stone's model is achieved relatively quickly. For immiscible displacements, there are two regions in the mixed zone, as in the 1D displacements: a slowly advancing region of zero oil saturation, and a region of gas flow with immobile oil present. The segregation length calculated from fluid properties in the inner zone of zero oil saturation could be greater or less than the actual segregation length. At fixed injection rate, modified SWAG injection (simultaneous injection, with water injected higher in the formation than gas) results in up to 71% longer segregation distance compared to co-injection for first-contact-miscible displacements, 110% longer for multiple-contact-miscible displacements, and 130% longer for immiscible displacements, when injecting same amount of fluids at same injection rates. In layered reservoirs, placement of surfactant into lower-permeability layers is a key challenge to sweep efficiency. However, both layered reservoirs show very similar sweep efficiencies.

In 2008 kwam de tweede Deltacommissie met het voorstel om het waterpeil van het IJsselmeer in de toekomst met 1,5 m te verhogen. Door de verwachte zeespiegelstijging zal het namelijk steeds moeilijker worden om het overtollige water van het IJsselmeer af te voeren naar zee. Om dit onder vrij verval te kunnen blijven doen is een peilopzet noodzakelijk, met ingrijpende dijkverhogingen tot gevolg. In dit afstudeeronderzoek zijn een aantal alternatieve maatregelen onderzocht, waarmee in een betere beheersing van het IJsselmeerpeil kan worden voorzien. Op deze manier kan grootschalige dijkverhoging wellicht worden voorkomen. Het afstudeeronderzoek spitst zich toe op twee zgn.“Alternatieve Beheersmaatregelen” waarmee, tijdens en voorafgaande aan een hoogwater op het IJsselmeer, het peil kan worden verlaagd. 1. Reduceren van de IJsselafvoer met behulp van een nieuw regelwerk in de Pannerdensche Kop; 2. Vergroten van de uitstroom door tijdens extreem hoog water in het IJsselmeer, het Markermeer (incidenteel) als Noodbuffer in te zetten. Naast deze alternatieve beheersmaatregelen is tevens gekeken naar de optie van bemaling via de Afsluitdijk. Hiervoor is, op basis van het meest extreme klimaatscenario volgens het KNMI, een schatting gemaakt van de maximaal benodigde pompcapaciteit bij verschillende combinaties met beheersmaatregelen. Daarnaast zijn ook globaal de (pomp)kosten berekent om het huidige peil in de toekomst te kunnen handhaven.

In the past few years, a new spirit for the exploration of the Solar System spread among the space community and reaching the Moon has been set as the first step of this new program. In this frame, going back to the Moon is needed to familiarize with a new way of living in a different environment, adapting to it and testing new technology. It is also true that, at the rate we are consuming the terrestrial resources, we will soon run out of them. This will put us in front of a dramatic change in our life style. Moreover, it is not unlikely that an asteroid could impact the Earth, causing extinction of many species and difficulties for survival. Then, these unpredictable reasons increase the importance of exploring and adapting to new extraterrestrial environments. Therefore, a feasibility study of a mission to the Moon to set up a permanent base has been carried on. The first part is concerning the delivery of the lunar payload into a LEO parking orbit. For this, the analysis of the capabilities of existing launchers is performed. The ascent trajectory problem is tackled by formulating it as an initial value problem (IVP), in which, given the launcher’s initial conditions, the state vector is propagated following a control law optimized to give the largest payload mass. Moreover, the launcher is subject to constraints dictated by the mechanical and thermal properties of the launcher itself. The optimal control law is sought by means of a Particle Swam Optimization method, which simulates the behavior of a flock of birds searching for food. Single and multi-objective optimization is performed. Single-objective optimization aims at maximizing the payload mass satisfying path constraints and the boundary constraints dictated by the orbital elements of the final orbit. Multi-objective optimization aims at maximizing the payload mass and minimizing the error on the final orbit simultaneously. Other experiments include the optimization of the two aforementioned objectives and the minimization of the violations of the path constraints. It has been found that, to fulfill the requirements of the lunar campaign, a very tight schedule and international cooperation is needed. Yet, existing launchers can be used for this mission for cargo expeditions. However, it is strongly suggested to commence development of a manned launcher and a spacecraft capable to land and host astronauts for multiple days on the Moon.

Understanding the Sun's natural processes helps us to understand how the Earth responds to the Sun's variations and helps improve our ability to predict its behavior. A probe in polar orbit around the Sun would be able to help provide a more complete picture of the Sun by studying coronal features from various angles, by linking particle and field observation to images of the Sun, by determining the magnetic structures and convection patterns in the polar regions of the Sun, and by following the evolution of solar structures over a full solar rotation. Previous theses have tackled the transfer from Earth to Solar Polar Science Orbit by using solar sails to propel the spacecraft. An alternative is a spacecraft using solar electric propulsion. This offers the advantage of a spacecraft that is more maneuverable, less mechanically complex, and is based on proven technology. Unlike the solar sail spacecraft however, this requires the spacecraft to carry propellant onboard to perform the transfer. An almost entirely analytical implementation is constructed, featuring the use of the shape-based approach (exponential sinusoid) to model the transfer. The implementation connects multiple shapes by way of gravity assist at specified planets, and uses Edelbaum's theory to model the remaining necessary inclination change, to investigate a transfer from Earth to a solar polar orbit at 0.4 AU distance from the Sun. An optimal solution is sought using an optimization strategy consisting of a random (Monte Carlo) method to perform an initial exploration of the search space, a global (Genetic Algorithm) method, and a local (Nelder-Mead) search method to refine the optimum located by the global method. The goal is to minimize propellant mass and transfer time, while maintaining a realistic transfer that does not violate various imposed constraints (such as departure and arrival velocity). Two solar electric propulsion options are offered (one performing a swing-by at Venus and another performing a swing-by at Jupiter), and compared to a reference solar sailing design. After experimentation it was found that the model is useful for simpler transfers, but a more involving implementation (using multiple separate coasting and thrust arcs) is required to give it the means to tackle more intricate problems. In addition, a more in-depth exploration of the inclination change maneuvers would be beneficial (especially with regards to a distance constrained maneuver).

Insulation failures in HV components may be caused by lower dielectric strength due to aging processes and by internal defects in the insulation system. It is known, that unlike voltage testing, measurements of the dielectric loss may give an absolute indicator for the quality level of the cable insulation. For several years the application of damped ac voltages for testing and diagnosis of HV components like power cables and stator insulation is being applied. This thesis is focused on the application of dielectric loss measurements to the insulation of service components. In particular, to discuss the principles of dielectric loss estimation using damped AC voltages theoretical investigation, calculation procedures will be presented and verified on laboratory experiments and field measurements.

Large rotating machines in all kinds of applications ages due to operating stresses. Since many years the condition of stator insulation in these motors and generators is investigated using measurement of partial discharge (PD) and dielectric loss factor (tan delta). In particular, off-line and on-line methods of applying PD detection have become common practice. The off-line PD detection technique is based on applying to single phases of the stator insulation an external 50(60) Hz power supply and detecting the partial discharges which inevitably occur in stator insulation. Based on the PD behaviour, the presence and type of discharging defects in the insulation, like slot discharges and end-winding discharges can be identified and evaluated for insulation condition assessment purposes. In contrast to on-line detection, with regard to interpretation rules for off-line PD detection there exist a large amount of experience. Off-line energiz-ing of the stator insulation can also be performed using Damped AC voltages 50-500 Hz (DAC), which has the advantage the test equipment is more mobile than AC test sets. This study describes the measurement technique of off-line PD and dielectric loss detection on stator insulation using damped AC. A test procedure for DAC is proposed based on the applicable AC standards, and results of DAC PD and dielectric loss measurement are presented. Based on laboratory investigation on a full scale stator insulation system as well as during field inspections on large motors, a comparison has been made of dielectric loss behaviour and PD behaviour – like tan delta levels, PD levels and phase resolved PD patterns – at 50 Hz AC stresses and at oscillating voltages. The usefulness of PD detection at oscillating voltage waves, and the usage of AC interpretation rules, has been discussed.

New Profile for the Amsterdam-Rhinecanal The aim of this thesis is to design a new profile for the Amsterdam-Rhine canal. The new profile needs to be well navigable and requires to have stable bank constructions. Simultaneously several social aspects have to be taken into consideration. The assignment is summarized as follows: Design a new profile of the Amsterdam-Rhine canal with a stable bank protection that takes future developments, durability and recreation into consideration. The history of the Amsterdam-Rhine canal shows that the draft of the vessels that use this canal has increased from 3.30 to 4.00 meters. This four-metre draft has been permitted since 1988 and was based on the dimensions of the push tow units. In the late 90s of the past century, a new generation of inland vessels made its appearance. Around 2002 problems to the bank constructions due to erosion were detected for the first time, possibly caused by the new generation inland vessels. The number of bigger inland vessels, particularly those in the VIa category has strongly increased over the past years together with the engine power and cargo capacity of many vessels (increase in scale). A representative canal section of the Amsterdam-Rhine canal, just north of Breukelen, has been chosen as research site. At this location erosion ranges from 0.20 to 1.70 meters within 15 meters distance of the sheet piles. The possible cause of this erosion has been further investigated in this report. Also research has been done to determine the governing hydraulic load, which is generated by governing vessels overtaking another vessel. The governing situation is defined as follows: a Rijnmaxship (135x17x4.00 m) overtaking a four barge push-towing vessel (198x22.8x4.00 m). In this situation, the return current is governing compared to a situation when loads from the main and bow thrusters are considered. The return current has been calculated with the 1D model DIPRO. DIPRO has also been used to validate the 2D model in Delft3D, to further elaborate the return current in the 2D model. The 2D model in Delft3D has been used to determine the maximum return currents around the two governing vessels. These values have been translated to the bottom of the canal by calculating the erosion. From these results can be concluded that canal profile (2) has twice the amount of erosion compared to canal profile (3). In this report canal profile (3) is recommended as the new normative canal profile for the Amsterdam-Rhine canal. Canal profile (3) is a combination of a box profile with a sloped upper bank and bottom, with in the middle a waterdepth of 7.60 meter. The depth in front of the sheet pile is 6.00 meter. The wet cross section is 751 m2. The bank construction consists of a sheet pile with a slope. The outcome of this thesis is a design for a new representative canal profile in the Amsterdam-Rhine canal. The normative hydraulic load (return current) causes minimum erosion to the canal bottom, which keeps the bank construction stable. Next to this the design proves that environmental and recreational purposes can be well combined in coherence with social developments.

In 2000 the Dutch government chose a new point of view for the Dutch rivers: “Room for the River”. This viewpoint is the basis for a new approach of high water protection in the Netherlands. Instead of strengthening and raising the dikes, solutions must be based on space and spatial quality. One of the suggested measures is the addition of secondary channels. The purpose of these channels is enlarging the conveyance area and the ecological role of the river. Maintaining the profile of these channels involves substantial financial consequences. Finding a sustainable solution for undesired erosion or sedimentation is the main focus of this study. The research question is stated as follows: “How can the undesired erosion or sedimentation in secondary channels be corrected with a temporary but sustainable solution in the form of surface screens?”. The main part of this study is an experimental study on the effects of surface screens on a mobile bed. The design of the physical experiments requires choices about the geometry of the flume. The experiments were carried out with a straight flume and with a dividing wall. Preparing the experiments requires information about the flume facility. The experiments have been carried out in the Environmental Fluid Mechanics Laboratory of DUT. The upstream boundary conditions are discharge and velocity distribution. The downstream boundary condition consisted of a fixed water level. The water level was kept constant along the natural slope of the surface. The experiments consist of taking velocity and bed level. The angle of attack and the penetration depth were chosen to be variable. The angle of attack was varied between 15 and 25 degrees. With these relatively small angles the screen acts as guidance for the flow, instead of an obstruction. The penetration depth was varied between 20% and 60% of the water column. The initial test run determined the optimal measurement duration and the initial equilibrium. Four representative cases have been described in detail, giving support to the general conclusions. The flow pattern changes under influence of the surface screen. The main flow direction is guided by the screen, introducing a transverse velocity at the surface. As flow continuity in the flume has to be maintained, the water near the bottom is forced to have a transverse velocity in opposite direction. Redistribution of the suspended transport and the bottom transport was induced. This generated locations were the actual transport did not meet the transport capacity, which gives rise to morphological changes. Next to the spiral motion the screen had an effect on the longitudinal flow velocities. The attacked side of the flume experiences a higher velocity, thereby having a higher transport capacity. This higher capacity gives rise to local erosion of the bed. At the unattacked side, sedimentation occurs, thereby rising the bed level. In the B-series of the experiment a dividing wall was added. The screen in front of the bifurcation gave rise to the same two processes, but the wall introduced an extra effect. The screen influenced the bifurcation relationship. The bed level adapted to the new conditions. The upstream effect of the bifurcation is explained by changes in water level topography, thereby influencing the backwater curve. In general the wall amplified the morphological development of the bed. Finally some suggestions have been made for the practical application of surface screens. In general the screens can be applied in a (secondary) channel or in front of a bifurcation. The use of a screen inside a channel has an advantage not to interfere with the navigation channel. The advantage of a screen in front of a bifurcation is influencing two channels simultaneously. One of the main disadvantages of the latter is the possibility of disturbing the delicate bifurcation relationship. When carefully implemented this effect can simultaneously be the main advantage of this screen layout, as the morphological response increases.

Introduction Dong Lam Cement Factory is developing a new clinker plant in Thua Thien-Hue Province, Vietnam. The clinker has to be exported towards Ho Chi Minh City, where it is grinded into cement and used for the construction industry. For the clinker production coal is needed and has to be imported. To make the in- and export possible a new dedicated seaport is required to allow for 15,000 dwt clinker vessels and 7,000 dwt coal vessels. Objective The objective is to design a port with sufficient capacity to handle the predicted cargo flow and which offers acceptable conditions for the ships to enter. The effective berth and hinterland capacity have to be determined such, that turnaround times are within limits. To create safe conditions, the vessels need to have enough space for manouevring in the wet port area. These manoeuvres can be seriously disturbed by wind, wave, currents and siltation on the long term. To ensure the workability of the port these effects have to be limited. Analysis To determine the effective berth capacity the queuing theory is applied. In phase 1 and 2 one clinker and one coal berth satisfy with effective capacities of respectively 700 and 175 t/h respectively. In phase 3 two clinker and two coal berths are needed with the same loading/unloading rates. To get insight in the environmental boundary conditions, field data is collected and analysed thoroughly. In Vietnam the wind climate is governed by the South-East Asian monsoon system, with a dominant SE direction and strong NNE winds. The wave climate is directly influenced by the wind climate and shows a similar pattern. With regard to extreme conditions, once a year a tropical storm lands in the vicinity of the port site. These storms are accompanied by strong wave conditions, coming from E to SE direction. Having frequent waves from the NNE and SE, littoral transport is generated in north- and southward direction. Nevertheless, the northward transport is clearly dominant. Currents are heading SE for most of the time. Synthesis Four different layouts are developed for phase 3 of the project. Two of them are dismissed in an early stage, because of unfavourable conditions. The other two layouts – the 'coastal' and 'offshore' alternative, are evaluated with a cost-value approach. In this approach the value of each design is assessed by means of a MCA. Evaluation The following criteria are taken into consideration: navigation, tranquillity at berth, coastal impact, sedimentation, ease of cargo handling, safety and flexibility. Regarding navigation and wind, wave and current hindrance, no significant differences are found. It turns out that the most important difference is found in the coastal impact. The coastal alternative will cause erosion along 7.5 km of coastline with a maximum retreat of 100 m. Instead, the offshore alternative affects 'only' 3 km with maximum retreat of 70 m. The other element of the cost-value approach is the costs. The investment costs for the coastal alternative are 64.1 M$, which include the dredging works, breakwater and quay construction. The costs for the offshore port amount 77.5 M$, which entails the dredging works, breakwater, jetty quay and trestle construction. The relative low costs for the coastal alternative are achieved by applying the cut-and-fill balance; the dredged sand is used as breakwater foundation. Maintenance dredging costs are 1.75 M$ and 0.9 M$ for respectively the coastal and offshore alternative. To finish the cost-value approach the value/costs ratio is taken for both port layouts. The coastal alternative (0.9) turns out to be a better port layout than the offshore alternative (0.77).

Research Questions - How to design a recreational route through the Dutch Delta that generates awareness of the characteristics of the different deltascapes? - How to design a series of pavilions along a recreational route that generates awareness of the relation to water in the deltascapes? - How to design a pavilion that reflects the characteristic relation to the water of the deltascape it is situated in?

Door de klimaatveranderingen voorziet de Deltacommissie 2008 problemen voor het Rijnmond gebied. De Maeslantkering en andere stormvloedkeringen zullen vaker moeten sluiten. Ook zullen de rivierafvoeren vaker extreme waardes aannemen. De kans dat een stormvloed samenvalt met een extreem hoge rivierafvoer neemt daarom toe. In het geval van een dergelijke combinatie, kan het rivierwater niet afgevoerd worden naar de Noordzee en ontstaan er problemen voor het Rijnmond gebied. In het deltarapport van de Deltacommissie 2008 wordt een ‘Afsluitbaar Open’ Rijnmond geadviseerd. Deze oplossing houdt in dat ten tijde van een combinatie van stormvloed en extreme rivierafvoer, vier nieuw te bouwen keringen het Rijnmond gebied afsluiten en de rivierafvoer leiden naar het Hollands Diep, de Haringvliet en de grote Zeeuwse wateren. In deze wateren zal het rivierwater tijdelijk geborgen worden en als de stormvloed is gaan liggen zal het rivierwater gespuid worden op de Noordzee. Het doel van dit afstudeerrapport is om een duurzaam en innovatief ontwerp te maken voor de kering in de Beneden-Merwede, de Merwedekering. Om dit ontwerp te maken wordt eerst het huidige systeem onderzocht. Er wordt gekeken naar de ontwikkeling van het watersysteem, de huidige keringen, de stromingen in het gebied en de dijkringen met de betreffende normfrequenties. Ook wordt het ‘Afsluitbaar Open’ Rijnmond plan onderzocht en worden de daaruit volgende randvoorwaarden voor de Merwedekering bepaald. Vervolgens is er naar een geschikt type kering gezocht. In totaal zijn elf mogelijke keringen onderzocht en beoordeeld. Door deze keringen te beoordelen op diverse criteria en te kijken naar de kosten, kan de beste kering bepaald worden. Voor de Merwedekering blijkt dat een sectordeurkering het meest geschikt zijn. Wegens een persoonlijke voorkeur is er echter verder gewerkt met een hydraulische kleppenkering. Er wordt voor gekozen om de kleppen uit te voeren in hogesterktebeton. Hogesterktebeton heeft minder onderhoud nodig dan staal en kost op lifecyclebasis een stuk minder. Tevens zijn er door de hogere sterkte van het beton slanke kleppen mogelijk. In het ontwerp van de kering zijn er veel variabelen, onder andere de diepte van de fundering, de aangrijppunten van de cilinders, het aantal cilinders, de manier van inspectie en de bouwmethode. In het uiteindelijke ontwerp is er gekozen om de cilinders aan te laten grijpen op 6,6m van de onderkant van de klep. In dat geval is het moment in de klep relatief klein en treden er relatief kleine trekkrachten op in de kleppen. Er wordt gekozen om twee cilinders per klep toe te passen. Om de kleppen en de cilinders te kunnen inspecteren worden onder de kleppen compartimenten gemaakt die zijn te bereiken via een tunnel die door de fundering loopt. In de ruststand dienen de kleppen als deksels op de compartimenten. De toegangstunnel kan gecombineerd worden met een fiets- en voetgangerstunnel. Door de kering in twee grote delen prefab te bouwen, kan de kwaliteit van het beton gegarandeerd worden, is er minimale hinder voor de scheepvaart en is er geen bouwput nodig. Bij deze bouwmethode worden de twee delen over het water vervoerd en ter plaatse afgezonken. Door de klep voor te spannen is het mogelijk de klep slank uit te voeren zodat het gewicht van de klep beperkt blijft. Tevens is gebleken dat de optredende trillingen in de klep geen problemen veroorzaken. De totale bouwkosten van de Merwedekering zijn 209 miljoen euro met een afwijking van 30%. Het gepresenteerde ontwerp is een duurzaam ontwerp met betrekking tot de levensduur, de milieuvriendelijkheid, het lagere onderhoud en de slijtage. Tevens is het een innovatief ontwerp met betrekking tot de prefab bouwwijze, de mogelijkheid tot eenvoudige inspectie onder water, de materiaalkeuze en de synergie met andere functies.

Light emitting diode (LED) based systems are considered to be the future of lighting. We consider the problem of energy-efficient illumination control of such systems. Energy-efficient system design is based on two aspects: localized information of occupancy and optimization of dimming levels of the LEDs. Specifically, we are interested in minimizing the power consumption of an LED system, subject to providing uniform illumination at a pre-specified level around occupied zones, by determining the dimming levels of the LEDs. Localized occupancy information (i.e. occupied zones) is determined by an ultrasonic array sensor while providing a natural interface for illumination control. We present algorithms for localizing and tracking an occupant in an indoor environment. We show that the optimization problem for illumination can be solved by linear programming and use the simplex algorithm to determine the dimming levels. The efficacy of the system is evaluated with numerical simulations and experimental data.

To solve complex problems brainstorming with a Group Support System can be a helpful tool. Social comparison and association effects are factors that stimulate the generation of creative and high quality ideas or concepts. Also, the GSS’ capabilities that allow a group to work in parallel contributes to the swiftness with which a fast growing set of ideas is generated. Groups of 10 to 15 are able to produce 100 to 150 ideas in as little as 15 minutes. The set of generated ideas however also has some limitations. Typically the set of ideas is characterized by redundancy, ambiguity, off-topic ideas and a lack of shared understanding. Extracting the key ideas from such a large set of ideas is time consuming and easily cause the facilitator and participants to suffer from cognitive overload. Extracting the key ideas is a process in which the group uses a combination of selecting and summarizing ideas and uses clarification techniques to create shared understanding. To address these challenges, groups and facilitators can benefit from methods and techniques to effectively extract the key ideas from the brainstormed list of ideas, without losing any promising ideas. Such techniques and methods are typically referred to as convergence methods. In interviews with professional facilitators we indeed found that they considered convergence to be difficult and time consuming. Also a large body of literature, mainly GSS case studies, was found that describes hurdles to convergence. These hurdles include (1) information overload at the beginning of a convergence task and (2) the cognitive effort required to complete a convergence task. Therefore the main research question of this thesis is: ‘how can convergence processes become more successful and effective?’. Based on an analysis of the current set of methods for convergence we identified four opportunities to improve the successfulness and effectiveness of a convergence process. The methods included in this study originate from the ThinkLet library, the method database of the International Association of Facilitators (IAF) and from a literature review. The identified opportunities are: • Removing the task of detecting redundant concepts away from the facilitator to lower his/her workload. • Improving the current hurdles that exist when converging in a parallel way, as is done is the FocusBuilder thinkLet among others. The current limitations of this thinkLet include: o Lack of comprehensiveness of the end result o Inability for the facilitator to monitor the process • Creating a scalable and fast pre-selection method. • Improving support for inexperienced facilitators to manage a convergence process in a large group. Classifying and comparing the methods found was possible by using a classification scheme based on two axes, (1) the output of a method and (2) the way of working implied by a method. By using the example of a creative problem solving workshop, in which we tried to find a match between a method for convergence and a convergence task for different scenarios, we have identified the opportunities for improvement. The differences in the scenarios were in the number of participants and facilitator skill level. In response to these opportunities we have designed three artefacts. One new thinkLet, Divide&Conquer, is developed that enables large groups to quickly make a pre selection of concepts. Secondly we designed a modifier to the FocusBuilder thinkLet. This thinkLet supports the creation of shared understanding, achieves a reduction of the concepts under consideration and removes redundant concepts from a brainstorm artefact in a scalable and fast way. Thirdly a technique for similarity detection, normally used for plagiarism detection and automatic grading of written texts, is adapted and evaluated for use to detect redundant concepts in a brainstorm or convergence artefact. The technique uses normalized vector representations of concepts based on a thesaurus to detect similar concepts. To assess the effectiveness and success of the designed artefacts the following process and result oriented metrics are used; process oriented: acceptance, satisfaction, facilitator dependence, scalability, commitment, productivity and efficiency. Result oriented: speed, redundancy, reduction, refinement, comprehensiveness, shared understanding (ambiguity), satisfaction and commitment. Evaluation in groups of the technique for similarity detection, the new Divide&Conquer thinkLet and the modified FocusBuilder thinkLet revealed that: • Even with a moderate detection rate of 50% participants are able to remove redundant concepts faster than participants that did not use the artefact in which concepts were ordered according to the automatic detected redundancies. Evaluation however is limited to one case study. Further evaluation is needed to validate the results and research the use of similarity detection within the new and other thinkLets. • The Divide&Conquer thinkLet can be used within groups to quickly make a pre-selection of concepts that the group deems worthy of paying further attention to. The process and results of the thinkLet were accepted by the participants of two workshops, however the process needs thorough explanation before the start to reach agreement on the process. The thinkLet achieves a pre-selection quicker than other pre-selection methods because in principal less votes than the number of participants are collected per concept. Based on the average value and standard deviation it is decided whether more votes per concept are needed. This increases speed and therefore scalability of the pre-selection process. The pre-selections made in the evaluation workshops with this thinkLet contained only on-topic items and reduced the original brainstorm artefact by 50% on average with a standard deviation of 10%. Besides explaining the process and presenting the results no facilitator efforts are required. • The modified FocusBuilder thinkLet can be used on a brainstorm artefact directly or after a pre selection has been made. The thinkLet fosters the creation of shared understanding and achieves a (further) reduction in the number of concepts under consideration by removing and summarizing redundant concepts and removing off-topic concepts. The thinkLet uses sub groups of participants that work on sub sets of concepts in parallel and convergence is achieved in three or four rounds. In previous case studies the comprehensiveness of the end result was too low. We removed the first round from the thinkLet, in which the participants work alone, to limit participant bias. Evaluation revealed that the comprehensiveness of the end result increased, without changing any other values that already were positive. Because of the parallel way of working the thinkLet is fast and scalable. Facilitator interventions are needed to explain the process and to present the end result, the real convergence effort is executed by the participants, therefore facilitator dependence of this thinkLet is low. The inability for the facilitator to monitor the process also is an opportunity for improvement of this thinkLet. A design for this is described, but is not evaluated. The outcome of this project is relevant for every professional interested in efficient collaboration within his project team, business unit or organisation. But also for practitioners, facilitators and collaboration engineers, because it proposes solutions for the time consuming step of convergence in GSS supported meetings. Further effort is however needed to evaluate the performance of the two thinkLets within more workshops, but the results indicate that the field of evaluation can be extended to organizations and professionals. Further research is needed to improve the accuracy of detection of redundant concepts and to integrate the detection technique within the two thinkLets mentioned.

This thesis gives a description of diagnosing life consumption and future life estimation of oil-impregnated paper insulated cable by using dielectric loss value. Dielectric loss values were investigated at different temperatures and different electrical field intensities in the laboratory. Based on laboratory measurements, a program was built; it can calculate the life consumption of paper oil-impregnated insulation by on-site dielectric loss measurements. Thermal aging was also taken into account for life consumption calculation in the program as an additional criterion. After that, future life estimation was calculated based on the result of life consumption and thermal aging theory in the program.

Decision support methodology for the remaining life evaluation vis-a-vis replacement of power cables.