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A Silicon-Based Combined Hot-Element and Calorimetric Anemometer
Get PDFA micro-fabricated silicon-based anemometer has been improved by employing a differential calorimetric measurement technique, while additional sensing information is extracted from the constant temperature heater. This combination improves the measurement range, as established experimentally and supported by finite element simulations. The straight-forward three mask fabrication process is also presented. The use of a lock-in amplifier to read out the sensing elements also provides additional information on the wind direction contained in the phase shift. With this information and theoretical basis, the combined anemometer leads to an increased measurement range and an improved <1% full-scale precision.</p
Measurement and Modeling of Initial Quench Development in Nb<sub>3</sub>Sn Accelerator Magnets
Get PDFAccelerator magnets are equipped with voltage taps and, on the test bench, with so-called quench antenna's to monitor the transient effects occurring during a magnet quench. Proper identification and localization of a quench origin is vital for understanding performance issues in Nb3Sn accelerator magnets. In this paper, we describe the physical phenomena that occur during the first few milliseconds of a developing quench and how they affect the signals as intercepted with the diagnostic tools. A better understanding of these phenomena allows for better resolution on determination of the quench start location. Measurements from Nb3Sn accelerator magnets are compared with a 3D thermal-electric PEEC-FEM model of a Rutherford cable. The voltage measured over the cable shows an accelerating build-up attributed to the transverse quench propagation in the cable cross-section, which is dominated by inductive effects that results in an avalanche of quenching strands. A slow-down in the voltage build-up then indicates the point at which all strands in the cable cross-section have quenched. This phase of the quench involves a significant current redistribution that creates a magnetic dipole moment picked up by a quench antenna. The harmonic quench antenna used in this work is used to reconstruct the location, magnitude, and direction of this dipole moment, which strongly depends on the start location of the quench in the cable cross-section, on the inter-strand contact resistances and on the magneto-resistance of the copper. It is shown how the quench start location in the cable cross-section can be determined from the time integral of the reconstructed dipole moment.</p
Mechanical and electromagnetic characteristics of MgB<sub>2</sub> wires & Cable-in-Conduit Conductors for fusion magnet application
Get PDFA study on a 4-stage sub-size MgB 2 Cable-in-Conduit Conductor (CICC), tested at the Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP), revealed a 20% degradation in critical current at 4.2 K compared to single-strand data. To address this issue, the mechanical properties of MgB 2 wires from Hyper Tech and WST were investigated, and two sub-size CICCs were manufactured using a “close-to-1-ratio” Twente design with smaller diameter wires. These cables demonstrated no significant degradation in critical current after cabling and compaction, nor after electromagnetic load cycling. The results indicate that the close-to-1-ratio cable design is optimal for brittle superconducting materials such as MgB 2, Nb3Sn, and BSCCO, as it minimizes mechanical stress and preserves superconducting properties. This design shows significant potential for the application of MgB 2 in next-generation fusion reactors, particularly in Poloidal Field (PF) coils, Correction Coils (CC), and feeders.</p
A CRISP-DM-based methodology for assessing agent-based simulation models using process mining
Get PDFAgent-based simulation (ABS) models are powerful tools for analyzing complex systems. However, understanding and validating ABS models can be challenging. Data-driven techniques, such as process mining, offer promising capabilities for addressing these challenges. Process mining enables the discovery, monitoring, and enhancement of processes by extracting insights from event logs. However, applying process mining to ABS-generated logs and interpreting the results is not trivial. Despite its potential, limited methodological guidance exists for using process mining in ABS evaluation. This paper proposes a methodology, grounded in the CRoss-Industry Standard Process for Data Mining (CRISP-DM), to assess ABS models via process mining. By integrating process mining techniques into the phases of CRISP-DM, we support the analysis of ABS behaviors and their underlying processes. We demonstrate our methodology using Schelling’s segregation model. Our results indicate that our proposed methodology effectively evaluates ABS models using event logs, enhancing model validity and supporting more informed decision-making.</p
Van onzichtbare achterblijver naar digitaal meedoen:Inzichten en succesfactoren van proeftuinen met het digitaal meedoen pakket
Get PDFDemocratic transition:Political accountability and policy responsiveness of directly elected mayors in Indonesia
Get PDFThis study explores the transformative impact of democratization and decentralization reforms on local governance in Indonesia, emphasizing the significance of direct mayoral elections introduced in 2005. Historically governed by an authoritarian regime for over three decades, Indonesia's shift toward democratic decentralization involved devolving responsibilities and budgets to local municipalities and reforming mayoral selection processes—from presidential appointment to direct election by local councils, and eventually, to direct voting by constituents. Central to these reforms was the requirement for mayoral candidates to present a development plan, fostering transparency, accountability, and policy coherence, thereby empowering local leaders to better address community needs. The research defines political accountability in terms of mayors’ responsibility to the populace and public spending, and policy responsiveness as tailoring actions to societal needs and improving outcomes. It seeks to assess how the move to direct elections influences mayoral accountability and responsiveness, addressing four core questions about institutional development, effects on public spending and societal well-being, the moderation of these effects by political competition and elite influence, and the fulfillment of election pledges—particularly in health sectors.The thesis contributes novel insights through four key aspects: firstly, an integrated analysis of how direct mayoral elections influence public spending and social outcomes, considering the persistence of clientelist practices; secondly, a conditional model that incorporates political competition, elite veto power, and local state capacity to explain variations in redistributive policies; thirdly, an examination of mayoral pledge fulfillment and its relation to accountability, revealing pragmatic and institutional factors influencing responsiveness; and finally, the application of mixed qualitative and quantitative methods—ranging from legal analysis to statistical modeling—providing a comprehensive assessment of Indonesia’s decentralization trajectory.Structured across five chapters, the research traces the evolution of legal frameworks, examines the effects of democratization on governance quality, develops a conditional redistribution model, analyzes pledge fulfillment, and discusses policy implications. Collectively, the findings highlight the complex relationship of formal institutions, informal practices, contextual factors, and political incentives shaping local governance in Indonesia’s transitioning democracy. This work offers valuable theoretical and practical insights for promoting accountable, responsive governance in decentralizing democracies worldwide
Enhancing the usefulness and usability of Drought Early Action Protocols through co-creation
Get PDFThe lack of saliency, credibility, and legitimacy of information in climate services constrains their use in decision-making. Co-creation processes involve end users, purveyors, and providers in an iterative approach to develop tailored climate services that are useful and usable. Such approaches facilitate contextual understanding, integrate different knowledges, and are key in bridging the gap between innovation and use.Co-creation approaches have been applied in climate service development over the past years. However, there has been little exploration on whether and how the process can be organised to ensure that the co-created climate services are sustainably used. Unpacking this relationship between co-creation and use enables an understanding of the factors to consider, and pathways to follow when co-creating climate services to effectively upscale innovation and sustainable use in decision-making.This research aims to identify the pathways through which co-creation processes contribute towards the use of climate services in decision-making. We follow and critically evaluate an ongoing co-creation process for the development of a Drought Early Action Protocol (and the revisions thereof) in Lesotho. We apply the Contribution Analysis method to evaluate the process with key stakeholders from the Lesotho Meteorological Services, the Disaster Management Agency, and the Lesotho Red Cross Society. Preliminary findings suggest that a combination of i) embedding the climate service in an already existing decision-making framework, ii) actively building the capacity of institutional staff to use the climate service, and iii) providing avenues for maintenance after the co-creation process, is a likely pathway a co-creation process may take towards ensuring use of the climate service. This work is beneficial to practitioners and researchers as it provides an empirically grounded explanatory account of the relationship between co-creation and the use of climate services
Innovative data solutions for inclusive cities:The IDEAtlas User Portal
Get PDFAddressing the challenge of mapping deprived urban areas (DUAs) globally requires both technical innovation and user engagement. The IDEAtlas project developed a novel approach to monitor DUAs by combining advanced Earth Observation (EO) technologies with a user-centered design. Central to this is our IDEAtlas User Portal, a data platform that provides scalable, accessible, and participatory mapping solutions in support of Sustainable Development Goal (SDG) 11.1.1. The portal provides outputs from a custom Multi-Branch Convolutional Neural Network (MB-CNN) model trained on freely available Sentinel-1 and Sentinel-2 data, enriched with ancillary open datasets such as building footprints. Presently, the portal offers binary settlement maps, with future plans to include deprivation severity indices, and multi-temporal urban growth maps for the period 2019 to 2023. A unique feature of the IDEAtlas platform is its two-tier access model: an open section offering 100 by 100 m gridded outputs for public use, and a protected section for sensitive, city-level data. In the protected section, users can validate outputs. The user validation is an essential element of our Living Labs and is done in the form of continuous stakeholder collaboration. Through Living Labs and iterative user feedback across eight global cities, the portal has demonstrated how involving local governments, NGOs, and community organizations can enhance data quality, relevance, foster ownership, and empower decision-making. Early user engagements, such as the update of Argentina's RENABAP informal settlement registry, highlight the portal's operational value. By coupling technological scalability with participatory validation. Thus, the IDEAtlas User Portal represents a significant step toward inclusive, evidence-based urban planning and policymaking
Nature-based sandy interventions:finding synergies between flood safety, beach recreation and nature
No full textSocio-economic pressures in coastal zones are rising worldwide, leaving increasingly less room for natural coastal dynamics. Identifying synergies between social and natural systems seems crucial for fostering sustainable coexistence and co-development. Recent multi-functional, nature-based interventions on the Dutch coast offer great potential in that respect. Constructed by mega-nourishment, these interventions aim at improving flood safety on a decadal scale by increased dune growth, while enhancing ecological and recreational value. Surprisingly, studies evaluating these innovative solutions paid little attention to how the social and natural systems interact in these human-made coastal landscapes (which we refer to as sandy anthropogenic shores, or SAS). We do not know whether these interactions strengthen or weaken the primary safety function of the nature-based interventions throughout its lifetime.Using the Hondsbossche Dunes and the Sand Motor SAS as Living Labs, we investigated how recreation, embryo dunes and flood safety co-evolve over time and across space. Based on field studies and a participatory modelling process we have integrated beach visitors’ behaviour with novel biomorphological models to evaluate the evolving functionality of the interventions.Simulations over 20–50 years showed that on wide, elevated SAS beaches, high recreation pressure constrained embryo dune formation, allowing for continued growth of the original foredune thus enhancing long-term flood safety. However, this synergy between recreation and flood safety came at the cost of ecological value. Further exploration of SAS design and recreation scenarios could reveal whether ways exist to achieve synergies among all three functions: recreation, flood safety, and ecological value
Using low-cost sensors and citizen science:Assessing thermal inequality in African slums
Get PDFUrban heat exposure is intensifying due to climate change and urbanisation, with disproportionate impacts on vulnerable populations. Unfortunately, many urban areas, particularly informal settlements, lack sufficient data for detailed analysis to understand these impacts. Traditional air temperature measurement methods—such as meteorological stations—are sparsely distributed in African cities, typically located on city outskirts (e.g., airports), and fail to capture localized temperature variations. This study explores the use of low-cost sensors and citizen science initiatives to measure air temperature with higher spatial resolution in informal and surrounding formal settlements. A two-stage process is employed to evaluate data quality: first, statistically assessing biases in low-cost sensor (LCS) measurements, and second, employing Monte Carlo simulations to quantify uncertainties. The resulting data reveals significant temperature differences between informal settlements and surrounding formal areas, with informal settlements consistently exhibiting higher temperatures. This approach not only highlights the value of low-cost sensors and citizen science in generating high-resolution temperature data but also provides insights into thermal inequalities between different urban environments