Het ondergaan van een eenzijdige beenamputatie is een drastische chirurgische ingreep. Mensen, die na een amputatie in staat zijn om te lopen met een prothese, zijn functioneel onafhankelijker, en hebben een hogere kwaliteit van leven dan mensen die in een rolstoel belanden. Het is daarom niet verrassend dat het herwinnen van de oopvaardigheid één van de voornaamste doelen is tijdens de revalidatie. Doel van het onderzoek was om inzicht te krijgen in de factoren die het herwinnen en onderhouden van de loopvaardigheid van mensen na een beenamputatie beïnvloeden. Gebaseerd op de resultaten van het onderzoek kan geconcludeerd worden dat de fysieke capaciteit hierbij een belangrijke rol speelt. Een relatief kleine verbetering in de capaciteit kan al resulteren in significante en klinisch relevante verbeteringen. Hoewel geavanceerde prothesen de mechanische belasting van het lopen met een beenprothese verminderen, kan een ineffectieve balanscontrole deze positieve resultaten weer tenietdoen. ABSTRACT Undergoing a lower limb amputation is a life-changing surgery. The ability to walk greatly influences the subject's functional independence and quality of life. Not surprisingly, regaining walking ability is one of the primary goals during prosthetic rehabilitation. The primary aim of the research performed was to enhance our understanding of some of the factors that influence the ability to regain and maintain walking after a unilateral lower limb amputation. Based on the results we can deduce that a person's physical capacity plays an important role in their walking ability. Relatively small improvements in capacity could lead to significant and clinically relevant improvements in people's walking ability. Furthermore, results show that sophisticated prosthetic feet can reduce the mechanical load experienced when walking with a prosthesis. Interestingly, inefficient balance control strategies can undo any positive effect of these prostheses.
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Post-earthquake structural damage shows that out-of-plane wall collapse is one of the most prevalent failure mechanisms in unreinforced masonry (URM) buildings. This issue is particularly critical in Groningen, a province located in the northern part of the Netherlands, where low-intensity ground shaking has occurred since 1991 due to gas extraction. The majority of buildings in this area are constructed using URM and were not designed to withstand earthquakes, as the area had never been affected by tectonic seismic activity before. Hence, the assessment of URM buildings in the Groningen province has become of high relevance.Out-of-plane failure mechanisms in brick masonry structures often stem from poor wall-to-wall, wall-to-floor or wall-to-roof connections that provide insufficient restraint and boundary conditions. Therefore, studying the mechanical behaviour of such connections is of prime importance for understanding and preventing damages and collapses in URM structures. Specifically, buildings with double-leaf cavity walls constitute a large portion of the building stock in the Groningen area. The connections of the leaves in cavity walls, which consist of metallic ties, are expected to play an important role. Regarding the wall-to-floor connections, the traditional way for URM structures in Dutch construction practice is either a simple masonry pocket connection or a hook anchor as-built connection, which are expected to be vulnerable to out-of-plane excitation. However, until now, little research has been carried out to characterise the seismic behaviour of connections between structural elements in traditional Dutch construction practice.This thesis investigates the seismic behaviour of two types of connections: wall-to-wall connections between cavity wall leaves and wall-to-floor connections between the masonry cavity wall and timber diaphragm, commonly found in traditional houses in the Groningen area. The research is divided into three phases: (1) inventory of existing buildings and connections in the Groningen area, (2) performance of experimental tests, and (3) proposal and validation of numerical and mechanical models. The thesis explores the three phases as follows:(i) An inventory of connections within URM buildings in the Groningen area is established. The inventory includes URM buildings of Groningen based on construction material, lateral load-resisting system, floor system, number of storeys, and connection details. Specific focus is given to the wall-to-wall and wall-to-floor connections in each URM building. The thickness of cavity wall leaves, the air gap between the leaves and the size and spacing of timber joists are key aspects of the inventory.(ii) Experimental tests are performed on the most common connection typologies identified in the inventory. This phase consists of two distinct experimental campaigns:o The first experimental campaign took place at the laboratory of the Delft University of Technology to provide a comprehensive characterisation of the axial behaviour of traditional metal tie connections in cavity walls. The campaign included a wide range of variations, such as two embedment lengths, four pre-compression levels, two different tie geometries, and five different testing protocols, including both monotonic and cyclic loading. The experimental results showed that the capacity of the wall tie connection is strongly influenced by the embedment length and the tie geometry, whereas the applied pre-compression and the loading rate do not have a significant influence.o The second experimental campaign has been carried out at the laboratory of the Hanze University of Applied Sciences to characterise the seismic behaviour of timber joist-masonry cavity wall connections, reproducing both as-built and strengthened conditions. Twenty-two unreinforced masonry wallets were tested, with different configurations, including two tie distributions, two pre-compression levels, two different as-built connections, and two different strengthening solutions. The experimental results highlighted the importance of cohesion and friction between joist and masonry since the type of failure mechanism (sliding of the joist or rocking failure of the masonry wallet) depends on the value of these two parameters. Additionally, the interaction between the joist and the wallet and the uplift of the latter activated due to rocking led to an arching effect that increased friction at the interface between the joist and the masonry. Consequently, the arching effect enhanced the force capacity of the connection.(iii) Mechanical and numerical models are proposed and validated against the performed experiments or other benchmarks. Mechanical and numerical models for the cavity wall tie and mechanical models for the timber joist-masonry connections were developed and verified by the experimental results to predict the failure mode and the strength capacity of the examined connections in URM buildings.o The mechanical model for the cavity wall tie connections considers six possible failures, namely tie failure, cone break-out failure, pull-out failure, buckling failure, piercing failure and punching failure. The mechanical model is able to capture the mean peak force and the failure mode obtained from the tests. After being calibrated against the available experiments, the proposed mechanical model is used to predict the performance of untested configurations by means of parametric analyses, including higher strength of mortar for calcium silicate brick masonry, different cavity depth, different tie embedment depth, and the use of solid bricks in place of perforated clay bricks.o The results of the experimental campaign on cavity wall ties were also utilised to calibrate a hysteretic numerical model representing the cyclic axial response of cavity wall tie connections. The proposed model uses zero-length elements implemented in OpenSees with the Pinching4 constitutive model to account for the compression-tension cyclic behaviour of the ties. The numerical model is able to capture important aspects of the tie response, such as strength degradation, unloading stiffness degradation, and pinching behaviour. The mechanical and numerical modelling approach can be easily adopted by practitioner engineers seeking to model the wall ties more accurately when assessing URM structures against earthquakes.o The mechanical model of timber-masonry connections examines two different failure modes: joist-sliding failure mode, including joist-to-wall interaction and rocking failure mode due to joist movement. Both mechanical models have been validated against the outcomes of the experimental campaigns conducted on the corresponding connections. The mechanical model is able to estimate each contribution of the studied mechanism. Structural engineers can use the mechanical model to predict the capacity of the connection for the studied failure modes.This research study can contribute to a better understanding of typical Groningen houses in terms of identifying the most common connections used at wall-to-wall and wall-to-floor connections in cavity walls, characterising the identified connections and proposing mechanical models for the studied connections.
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This thesis is about dilemmas, discretionary space and ethics in public welfare. In my position as a lecturer of ethics in socio-legal practices I am concerned with the way in which these practices open up to an ethical development of their professionals. Thus, this thesis is a search for the most fundamental themes and issues in understanding and judging public welfare as a, perhaps, ethical socio-legal practice. In the field of public services professionals function as the intermediary between government and citizen. In their daily work public welfare professionals take care of the important societal task and goal of poverty alleviation. During the last decades, public welfare has developed into a civil right that involves many obligations on the part of the client in return. The requirement to see to it that the client fulfils these obligations has complicated the public welfare professional’s task of helping citizens in need.
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Nederland streeft naar een verduurzaming van het energiesysteem. In 2020 moet 14% van onze energie duurzaam opgewekt zijn, waarbij de zon, naast wind, als belangrijkste duurzame energiebron gezien wordt. Systemen voor geconcentreerde zonne-energie kunnen worden ingezet voor het opwekken van elektrische en/of thermische energie. Grootschalige systemen (multi-MW) met spiegels worden reeds toegepast in zonnevelden. Het HAN Lectoraat Duurzame Energie werkt al enige jaren aan innovatieve systemen met lenzen waarbij naast het concentreren van direct licht het overblijvende diffuse licht beschikbaar is voor verlichting van de onderliggende ruimte. We willen de in eerdere projecten opgedane kennis en ervaring nu inzetten in een nieuw project, waarin we streven van prototype naar toepassing te komen. De bedrijven zijn benaderd over de nog openstaande vragen. Hieruit is een nieuwe onderzoeksvraag gevormd: Hoe kan voor systemen van geconcentreerde zonne-energie voor toepassingen in glastuinbouw en gebouwde omgevingen voor de productie van zowel elektriciteit als warmte, de energie-opbrengst verhoogd worden door een optimaler gebruik van de lichtinval en met een compacter en duurzamer systeem? In dit project, CONSOLE (acroniem voor CONcentrated SOLar Energy), gaan we werken aan het optimaliseren van de bestaande systemen en het ontwerpen van verbeterde (hybride) systemen voor het opwekken van warmte en elektriciteit in kassen en gebouwde omgeving. We gebruiken hiervoor zowel modellering als meten en testen en komen vanuit een inventarisatie tot een pakket van eisen wat uiteindelijk tot verbeterde prototypes leidt die geschikt zijn voor commerciële toepassing. We doen dit vanuit een nauwe samenwerking met 12 MKB’s, een branche-organisatie en een Centre of Expertise. Daarnaast is er een directe koppeling met het onderwijs, door de betrokkenheid van docent-onderzoekers en studenten in semesterprojecten, stages en afstudeerprojecten.
