19 research outputs found
Wave propagation in initially stressed orthotropic compliant tubes containing a compressible, viscous and heat-conducting fluid
No full textMechanical, Maritime and Materials EngineeringMechanical, Maritime and Materials Engineerin
Thermodynamica van de Irreversibele Processen: Multicomponent-diffusie, Symmetrierelaties, Reologie
No full textDe macroscopische thermodynamica van irreversibele processen, afgekort tot TIP, is een onderdeel van de continuümtheorie en probeert binnen het kader van de continuümopvattingen een algemene basis te ontwikkelen voor de beschrijving van de lineaire constitutie van de materie. De TIP streeft naar unificatie en algemenisering van de behandeling van systemen met een lineaire constitutie. Zij integreert de beschrijvingen van afzonderlijke vakgebieden als de mechanica, stromingsleer, magnetohydrodynamica, stof transport, thermodynamica, enz. Daartoe worden alle lineaire processen met dezelfde methodiek behandeld, die binnen de begrenzingen van de modelstellingen van het relevante systeem mogelijk zijn.Materials Science & EngineeringMechanical, Maritime and Materials Engineerin
Tipping Points in Community-Based Management: A design-science research approach to study Community-based Management of domestic rural water points in Sub-Saharan Africa
No full textTechnology, Policy and ManagementEngineering, Systems and Service
An agent-based exploration of complex heat transitions in the Netherlands
No full textIn the Netherlands, a complex heat transition is taking place. Currently, the country's built environment largely relies on natural gas for heating. By 2050, the housing sector should, in principle, be free of this fuel. Changes in laws, policies, regulations, and technical solutions to achieve this goal will be challenging. Their implementation will require coordination and even cooperation between building owners (i.e. group decisions), as well as taking into account households' bounded financial rationality, households' heterogeneous decision criteria and preferences, and uncertainties introduced by changes in formal institutions.This dissertation explores these challenges from the perspectives of socio-technical systems, complex adaptive systems, and complex systems engineering. It addresses the question: How could the heat transition in the Netherlands be influenced by homeowners’ individual and group decisions regarding investment in heating systems and insulation measures? Agent-based modelling, informed by recent policy developments and scientific literature, is the main method used for answering this question. This dissertation takes the application of this method to explore the heat transition in the Netherlands one step further.“An agent-based exploration of complex heat transitions in the Netherlands” is relevant for the following three audience groups. Firstly, researchers who develop computational models to study socio-technical transitions, and in particular, heat transitions in the Netherlands. Secondly, practitioners who develop or use those computational models to offer advice to different actors. Finally, this research is relevant for anyone interested in enabling heat transitions in the Netherlands, from households and neighbourhoods who are the end users of technologies, to public actors discussing and designing policy interventions.Energie and Industri
Brownse Dynamica van Verdunde Polymeeroplossingen
No full textForecasting the flow behaviour of non-Newtonian fluids always has been subject to investigation, especially in the oil-industry. In former times the flow models were solved analytically. Nowadays, because of the continuous increase in com puter power, more often numerical methods are used in solving the models. These methods can easily solve non-linear problems, which is (almost) impossible analytically. Brownian Dynamics is a numerical method, which explicitly reckons with the Brownian movements of a polymer, due to the surrounding smaller fluid molecules. This method is used to simulate a couple of standard experiments on a dilute polymer solution. The polymer is modeled by a bead-spring chain. In this investigation, several parameters are varied, resulting in different flow behaviour. The parameters that can be set are a) the equilibrium length of the segments of the polymer b) the chain force constant of the segments and c) the flexibility of the polymer. The results for the diverse values of the parameters are compared with analytic results, other simulations and experiments. Total agreement with theory is found for the Rouse-chain, justifying the method of the Brownian Dynamics. The transients of the viscosity and first normal stress coefficient for each of the three models resemble those' found in experiments. The steady-state values of the FENE-chain also show the shear-thinning behaviour which is found in experiments. The influence of pre-shearing on the transient elongational viscosity is also examined. The dependence on parallel pre-shearing is great as expected. On the other hand there is scarcely any effect of perpendicular pre-shearing.Applied SciencesFysische Stromingslee
Assessing alternative heating strategies in a Dutch neighborhood using a life cycle perspective and multiple household decision-making factors: Contributing to the heat transition in Dutch dwellings
No full textIndustrial Ecolog
District Heating Ownership: An exploratory case study to the preferences of Utrecht residents on ownership structures for new district heating systems
No full textSince the Netherlands possesses the largest natural gas reserve in Western Europe, most households depend on this resource for their heat provision. Of the total consumption of natural gas, 51% is used for heat provision to households. Both social problems with earthquakes related to natural gas exploitation and environmental problems with greenhouse gas emissions, challenge the country to find alternatives. One of these alternatives is using district heating in combination with renewable heat generation. Where district heating is already present, public resistance highlights price and inflexibility as unjust – as perceived by the monopolistic infrastructure (Janssen, 2015; Mulder, Paping, & Huis in 't Veld, 2014). While customers perceive injustice on one hand, on the other hand district heating is being considered as one of the alternatives for natural gas provision during the so called ‘heat transition’. Hence, the problem of injustice would affect more and more residents. Different types of ownership of district heating networks (e.g. private, public, cooperative) may offer opportunities to overcome or manage some of these downsides and improve the perceived energy justice. Considering this, the following question was researched: what ownership structures for new district heating systems would Utrecht residents prefer? Perceived energy justice is taken as a core concept supporting the preferences of Utrecht residents. The identified ownership types (public, private and cooperative) are comparatively reviewed by expert interviews on their strengths, weaknesses, opportunities and threats influencing their success in the heat transition. It was found that (1) there are external factors influencing all ownership types equally (like tax increase), (2) the institutional context often influences ownership structures contrastingly (e.g. market tradition). Also it was found that arguments in favour of private ownership often included business-oriented reasons. Arguments in favour of cooperative ownership often included influence-oriented reasons. Argument in favour of public ownership often included social-oriented reasons. Mixed ownership arguments often argue that – possibly – win-win situations occur, but at the cost of increasing transactions costs. The design space and its insights on ownership types, are used to perform an online survey to explore energy justice within residents (N=198). Respondents having higher education level than the average Utrecht population and a lower percentage of respondents living in social housing (-32%) limit the sample’s representativeness. Also, generalisability for places and neighbourhoods where less apartments are present, is limited (52% of respondents lived in apartments). We found indication (Figure 1 Ownership preferencesFigure 1) that most respondents appreciate the role of public organisations (e.g. public electricity grid operators and municipalities). Findings also suggest that network activities are the most suited for public ownership. Energy companies were most selected (61%) for the ownership of the generation activities. While community-owned heat cooperatives offer opportunities to enhance justice, this model was selected fewer times (45%-50%). Linking the energy justice preferences with the direct preferences on ownership it is concluded that three ownership structures are preferred (‘three streams’): integrated public ownership, competition on public network and integrated cooperative ownership. Within the context of the heat transition, we expect increasing the public influence – aiming for equal responsibility, socialised cost and benefits – would best address perceived injustice in new district heating monopolies. We also expect that in well-defined spatial communities, integrated heat cooperatives could offer perceived justice of the district heating natural monopoly. Thus far, aiming for competition was found to be limited due to the high costs. Despite being preferred, it seems to be less feasible (R. Haffner et al., 2016). The Master's programme Industrial Ecology is jointly organised by Leiden University and Delft University of Technology.Industrial Ecolog
Parvovirus B19 Pure Red Cell Aplasia In A Renal Transplant Recipient [aplasia Pura De Série Vermelha Secundária A Parvovirose Em Transplantado Renal]
No full text[No abstract available]30170Handgretinger, P.F.R., Schaefer, H.E., (2000) Pure red cell aplasia. Brit J Haematol, 111, pp. 1010-1022Wong, T.Y., Chan, P.K., Leung, C.B., Szeto, C.C., Tam, J.S., Li, P.K., Parvovirus B19 infection causing red cell aplasia in renal transplantation on tacrolimus (1999) Am J Kidney Dis, 34, pp. 1132-1136Ahsan, N., Holman, M.J., Gocke, C.D., Groff, J.A., Yang, H.C., Pure red cell aplasia due to parvovirus B19 infection in solid organ transplantation (1997) Clin Transplant, 11, pp. 265-270Flores, A.V., Ionescu, D.N., Melhem, M.F., Parvovirus B19 infection in immunocompromised host (2007) Arch Pathol Lab Med, 131, pp. 799-80
A recent overview of the integration of System Dynamics and Agent-based Modelling and Simulation
No full textModelling and simulation aim to reproduce the structure and imitate the behavior of real-life systems. For complex dynamic systems, System Dynamics (SD) and Agent-based (AB) modelling are two widely used modelling paradigms that prior to the early 2010’s have traditionally been viewed as mutually exclusive alternatives. This literature review seeks to update the work of Scholl (2001) and Macal, (2010) by providing an overview of attempts to integrate SD and AB over the last ten years. First, the building blocks of both paradigms are presented. Second, their capabilities are contrasted, in order to explore how their integration can yield insights that cannot be generated with one methodology alone. Then, an overview is provided of recent work comparing the outcomes of both paradigms and specifying opportunities for integration. Finally, a critical reflection is presented. The literature review concludes that while paradigm emulation has contributed to expanding the applications of SD, it is the dynamic combination of the two approaches that has become the most promising research line. Integrating SD and AB, and even tools and methods from other disciplines, makes it possible to avoid their individual pitfalls and, hence, to exploit the full potential of their complementary characteristics, so as to provide a more complete representation of complex dynamic systems.Policy AnalysisRivers, Ports, Waterways and Dredging Engineerin
An agent-based exploration of the effect of multi-criteria decisions on complex socio-technical heat transitions
No full textNatural gas for heating is widespread in the built environment of The Netherlands, where the government aims at limiting heat demand and reducing natural gas consumption over the coming decades. In the owner-occupied residential sector, this transition is complex and requires cooperation and coordination of individuals and groups that make investment decisions. We use agent-based modelling to explore the effect that various financial policies could have in an illustrative neighbourhood, given that households make multi-criteria and group decisions. In the scientific literature, this type of energy model seldom focuses on the adoption of competing technologies by households as individual and collective agents grouped in homeowner associations in multi-family buildings. To address the problem and knowledge gaps, we model individual preferences with a multi-criteria perceived lifetime utility submodel, and decisions as outcomes of individual preferences and a threshold voting system. We explore energy taxes (natural gas and electricity), regulated price of heat from networks, and subsidies (insulation and heat pumps). Under our assumptions, we found that combinations of fiscal policies, regulated heat prices, and subsidies can sometimes create incentives for households to disconnect from natural gas, but that steering the transition mainly with financial policies could prove ineffective. We also found that, in terms of collective CO2 reduction, some transitions in which only some households phase out natural gas could have results similar to some scenarios in which households only improve their dwellings’ insulation levels.Energy and Industr
