· · · Institutional Repository

Dit afstudeeronderzoek richt zich op het grondvervormingsgedrag naast aan te leggen bouwputten. Vooral bij diepe bouwputten in stedelijke omgeving is het onduidelijk hoe en waar het vervormingsgedrag, afhangt van de Nederlandse specifieke omstandigheden zoals de grondopbouw, belendingen en funderingen, tot stand komt.

The current method of minimally invasive harvesting the sural nerve in infants takes too much time. To reduce harvesting time a new Minimally Invasive Nerve Dissector (MIND) was designed. The MIND reduces instrument change by combining the two most used functions of the currently used instruments: firstly, the movement of the graft with the hook and secondly, the outwards motion of the micro scissors. Besides these two functions, the MIND was designed for a minimally invasive procedure and is much smaller than the current instruments. The MIND was evaluated on an artificial test facility simulating a leg of an infant. Using the test facility a test comparing the current instruments and the MIND was carried out. Measured were the time to harvest and the number of dissection instrument changes. The results of the test showed that both showed positive improvements with the MIND.

This study considers the feasibility of a special floating pier at the port of Caripito. This port, located along the Rio San Juan, is the port of embarkment for many oil fields in north-east Venezuela. A few years ago some dolphins at the port collapsed. These problems are mainly caused by river bank slidings. As a result one pier has not been used since. In this situation a floating pier might offer some interesting advantages: - the pier itself it not affected by river bank slidings; - meander processes can change the course of a river. If the pier can not be used at it's original place anymore, it can be moved to another; - the pier and the tanker follow the tide together. Loading operations are influenced less; - the pier can be build off site, at a place where work conditions are optimized. It is finally floated and transported to the right location. Until today floating piers have served at many cargo ports. Generally these cargo piers are very large. On the other hand conventional oil piers always have a small loading platform. It is mainly used to support the oil pipes which lead to the tanker. A floating oil pier can only be economically competitive if it is small too. A small floating platform can be displaced easily. This study will evaluate a new type of floating pier, which utilizes this ability: When the tanker has arrived, then it's head and stern mooring lines are fastened to buoys. Next the spring lines are fastened to the small floating platform. The tanker's winches pull the platform to it's hull. Now the oil loading process can be executed. Finally the platform is withdrawn towards the river bank and the tanker leaves the pier. Different aspects of the platform are investigated. The construction itself, it's stability, the wind and current forces on the tanker and on the platform, the resulting displacements of the tanker and the magnitude of the breasting energy. Unfortunately it must be concluded that the piers at the port of Caripito do not provide enough space. Nevertheless the movable platform will offer an interesting alternative when it is used in an area which provides more space than the Rib San Juan. It's main advantages are: - the tanker berths at some distance of the platform. This can be done in relatively bad weather conditions (e.g. with hardly any sight, strong winds). Tugs can be needed less or not at all; - tankers of any size can be served. The dimensions of the platform construct i on are not related to the size of the tanker nor to any forces on it. The platform can be used at a port where the size of the tankers might increase in the future; - the platform can be installed quickly (this might also be interesting for military operations).

Granular filters are used for protection against scour and erosion. For a proper functioning it is necessary that interfaces between the filter structure, the subsoil and the water flowing above the filter structure are stable. Stability means that there is no transport of subsoil material through the filter to the water above the filter, and that no filter material is removed by currents above the filter. Three types of granular filters can be distinguished; 1) Geometrically closed filter structures, 2) Stable geometrically open filter structures, 3) Unstable geometrically open filter structures. This research is focusing on stable geometrically open filter structures. Recently, a desk study has been carried out by Deltares resulting in a new theoretical formula for single layered geometrically open filter structures (CUR, 2010). Hoffmans improved the theoretical formula that had been founded by Deltares (Hoffmans G. , 2012) The goal of this research was to verify the formula found by Hoffmans [2012] for structures loaded by currents (flow parallel to the filter construction). As part of the verification of the design formula ten flume experiments were performed in the Environmental Fluid Mechanic Laboratory at Delft University of Technology. After the execution of the model tests an extensive analysis was made based on the performed model tests and model tests performed in the past (Bakker [1960], Haverhoek [1968], Wouters [1982], Konter et al. [1990], Van Huijstee and Verheij [1991] and Van Velzen [2012]). The analysis showed that the formula is valid for single layered geometrically open filter structures loaded by currents. Two adjustments to the design formula are proposed: 1. The relative layer thickness fits better when related to the nominal diameter of the filter material; 2. The alpha value proposed by Hoffmans [2012] is too high (new alpha values are 30% to 60% lower). The original formula as proposed by Hoffmans [2012] gives unrealistic values for situations with wide graded filter material. Model tests showed that the relative layer thickness is better represented when related to the nominal diameter of the filter material. The design formula can be used for design purposes. The design of a single layered geometrically open filter structure can be schematized in two steps; 1. Firstly, determination of the material that should be used for the top-layer; 2. Secondly, determination of the layer-thickness of the filter/top-layer taking into account filter and base material characteristics.

The project QBTEC is a company which designs, manufactures and sells deep-fry installations to companies with a focus on deep-frying. Deep-fry installations are the entire stainless steel wall, known from cafeteria for example. The company felt the urge to innovate, to maintain their leading market position. They had not been able to introduce innovations other than incremental innovations over the past years. They had ideas about the direction of automation, to enable control of the deep-fry process at customer’s location. They wanted to know if there was a market need for automation. However, it is decided to focus on the problem of innovation for QBTEC and the problem of controlling the deep-fry process for customers. Controlling the deep-fry process is defined as diminishing the influences during the process to control the result. Becoming pro-active Currently, QBTEC offers custom-fit products. The sales representatives of the company translate customer’s wishes to the design department, who build a custom-fit solution. A new customer request or frequent complaints lead to product improvements. This re-active approach to customer’s situation leads to incremental innovations. For QBTEC to become more innovative, a pro-active approach is needed. This approach enables to take away the causes, instead of fighting the symptoms. Expand with new products in current market To generate corporate growth in the future, it is recommended to apply a product development strategy. Developing new products, instead of deep-fry installations and components, for the current market entails a relatively small risk and provides opportunities to innovate. It enables the company to quickly adapt to customer’s changes. Project as first step and example This project can be seen as an example and first step of these recommendations towards corporate growth in the future. First of all, a research on controlling the deep-fry process goes beyond the current product and is therefore a suited direction for new product development. Secondly, research is conducted within the current market segment ‘recreation’. Preliminary research within different market segments has founded this choice. And finally, a pro-active research method is applied, to be able to understand the system of behaviour and to come to a more innovative solution. Research recreation market Eight snack locations within the recreation market are observed to find the influencing factors that cause an uncontrolled process and the relation between these factors. Observations are the appropriate method to research workflows. Observing the deep-fry process enables discovering the entire situation, real actions and unarticulated needs. The handlings of the employees at the snack location are observed from the moment an order is taken until the order is finished. Conclusions are drawn upon the observed problems, their causes and their consequences for the result. The pro-active approach provided this insight in the system structure of employee’s behaviour. It is concluded that a cognitive overload of the employees has its influence on the rest of the causes of occurring problems. To be able to control the deep-fry process, the risk or problems need to be decreased. Idea generation An internal and external creative session and individual brainstorms are conducted in the idea generation phase. These sessions have sharpened the system structure of the research and resulted in solutions to reduce the cognitive workload. The solution Ultimately, the Clock is chosen as a first step of future developments of QBTEC. The Clock is a system which displays the process on screens. It provides employees overview of the handlings yet to come. It shows when to do what and enables to anticipate on these moments to execute secondary handlings. This external representation of internal thoughts reduce the cognitive workload and therefore the risk of mistakes during the deep-fry process. The reduction of mistakes enables QBTEC’s customer to control their deep-fry process and reduce unwanted results. QBTEC as a specialist The product development of the Clock will be the first step towards the future vision of QBTEC. There are large opportunities for innovation within the current market. With a pro-active approach, the company is able to understand the customer’s entire situation. When acting upon this knowledge, the company is able to provide their customer a total solution for their business. QBTEC becomes a specialist in the deep-fry situation.

Stochastic properties of GNSS range measurements can accurately be estimated using a geometry-free short and zero baseline analysis method. This method is now applied to dual-frequency measurements from a new field campaign. Results are presented for the new GPS L5Q and GIOVE E5aQ wideband signals, in addition to the GPS L1 C/A and GIOVE E1B signals. As expected, the results clearly show the high precision of the new signals, but they also show, rather unexpectedly, significant, slowly changing variations in the pseudorange code measurements that are probably a result of strong multipath interference on the data. Carrier phase measurement noise is assessed on both frequencies, and finally successful mixed GPS-GIOVE double difference ambiguity resolution is demonstrated.

Shock wave boundary layer interactions (SWBLI) are a common phenomenon in transonic and supersonic flows. The presence of shock waves, induced by specific geometrical configurations, causes a rapid increase of the pressure, which can lead to flow separation. Examples of such interactions are found in amongst others rocket engine nozzles and on aerospikes, on re-entry vehicles, in supersonic and hypersonic engine intakes, and at the tips of compressor and turbine blades in jet engines. The interactions are important factors in vehicle development. Both the separated flow and the induced shock have been shown to be highly unsteady, causing pressure fluctuations and thermal loading. This generally leads to a degraded performance and possibly structural failure. The current work therefore aims to improve the physical understanding of the mechanisms that govern the interaction, with a special attention for the flow organisation and for the sources of the unsteadiness of the induced shock. In particular, the case of a reflecting incident shock is investigated, but the results find their application more generally in other configurations. Additionally, it is verified whether the interaction can be controlled by means of upstream fluid injection. To attain these aims, experiments were performed, comparing systematically several interactions for a range of shock intensities (producing incipiently separated and well separated flows) and under a number of flow conditions (Mach numbers of 1.7 and 2.3 and Reynolds numbers of 5,000 (‘low’) and 50,000 (‘high’)). This was done using the latest developments in the field of measurement techniques. A large amount of data was obtained for multiple interactions by means of a range of flow diagnostic techniques, yielding highly consistent results. A full field determination of the characteristic time scales by means of dual plane particle image velocimetry (Dual-PIV) has shown that the unsteadiness frequencies in the high Reynolds number incipient interaction span almost three orders of magnitude, demonstrating additionally the existence of low frequency dynamics of the reflected shock. The effect of control by means of air jet vortex generators (AJVGs) was thoroughly characterised, putting in evidence the generation of pairs of counter-rotating vortices of unequal strength that induce streaks of low and high speed fluid. These in their turn modify the separation bubble size without suppressing it. There is an inversely proportional relation between the reflected shock frequency and the bubble size. A scaling analysis was made, aimed at reconciling the observed discrepancies between interactions documented in literature. As part of this analysis, a separation criterion has been formulated that depends on the free-stream Mach number and the flow deflection angle only. In addition, a scaling approach has been derived for the interaction length based on the mass and momentum conservation. A conditional analysis has been performed based on the instantaneous separation bubble size. The generation and successive shedding of large coherent structures was found to be present also in absence of instantaneous flow separation. For the incipient cases, a link has been put into evidence between the separation region and the state of the upstream boundary layer. For the separated interactions, this link was absent and the shock unsteadiness seems to be mainly related to the separation bubble pulsation. The separation criterion in combination with the normalised interaction length represents a single trend line onto which all data for a large scope of documented interactions fall together with only a moderate scatter. This trend line predicts that the only way to effectively eliminate a separation bubble (without massive separation) by means of upstream control is by decreasing the displacement thickness of the incoming boundary layer. A scaling for the wall normal coordinate has been defined based on the interaction length with a correction for Mach number effects, producing a large resemblance in the geometric organisation of the mean and turbulent flow fields within the considered interactions. It can be concluded that multiple unsteadiness mechanisms are at work within the interaction, irrespective of the Mach number and the Reynolds number. It is proposed that the relative importance of the different mechanisms shifts with the imposed shock intensity. It seems that weak interactions without instantaneous flow separation should be governed by upstream effects only, with rather high shock frequencies. For incipient interactions, downstream effects start to occur; the region of high turbulence intensities displays mainly a lifting motion, producing a shock foot of varying strength and a shock unsteadiness that involves a time scales which can differ by at least one decade. Interactions with significant flow separation show mainly a translating motion, producing a low frequency unsteadiness and a shock foot of constant strength, which is in accordance with a free interaction behaviour. Concerning the Reynolds number and Mach number effects, it is concluded that for turbulent boundary layers, the onset of separation is Reynolds number independent. The interaction length is however governed by both the Reynolds number and the Mach number.

De opleving in de bouw van vrije-sectorwoningen, die gepaard gaat met een veel grotere nadruk binnen het woningbouwprogramma op de vrije sector, is voor het Nederlands Instituut voor Ruimtelijke Ordening en Volkshuisvesting (NIROV) de reden geweest een onderzoek op te dragen aan het Onderzoeksinstituut voor Technische Bestuurskunde (OTB) naar de consequenties van de bouw van vrijesectorwoningen voor de ruimtelijke ordening, de volkshuisvesting en de bouwnijverheid. De Directie Coordinatie Bouwbeleid (DCB) van het Ministerie van VROM en de Vereniging van Nederlandse Projectontwikkeling Maatschappijen (NEPROM) hebben eveneens financieel in het onderzoek bijgedragen. Het onderzoek is in twee afzonderlijke delen opgesplitst. Het eerst deel "De vrije-sectorwoningen; een historische en ruimtelijke analyse" biedt een kwantitatieve achtergrondstudie. In dit tweede deel getiteld "Vrije-sectorwoningbouw; consequenties voor de ruimtelijke ordening, de volkshuisvesting en de bouwnijverheid', wordt de eigenlijke probleemstelling van het onderzoek behandeld. Tijdens de werkzaamheden heeft een begeleidingscommissie de onderzoekers van deskundige adviezen en suggesties voorzien. Deze begeleidingscommissie bestond uit de volgende personen: drs. P.H. Bakker (Nederlandse Vereniging van Makelaars in onroerende goederen), ir. H. Gordijn (Directoraat-Generaal van de Volkshuisvesting), drs. L.A de Klerk (gemeente Rotterdam), drs. G.W. Middelkoop (Planologisch, Demografisch Instituut), drs. HJ. van Herwijnen (Vereniging Eigen Huis), ir. L.E.C. de Reus (Wilma Vastgoed), drs. N. Rietdijk (Nederlandse Vereniging van Bouwondernemers), drs. D. Vos (Pensioenfonds PGGM), dr. J.P. de Waart (DCB) en drs. J.MJ.G. Zoontjens (NIROV). De eindverantwoordelijkheid voor het onderzoek berust bij de onderzoekers.