The Smart Current Limiter is a switching DC to DC converter that provides a digitally pre-set input current control for inrush limiting and power management. Being able to digitally adjust the current level in combination with external feedback can be used for control systems like temperature control in high power DC appliances. Traditionally inrush current limiting is done using a passive resistance whose resistance changes depending on the current level. Bypassing this inrush limiting resister with a Mosfet improves efficiency and controllability, but footprint and losses remain large. A switched current mode controlled inrush limiter can limit inrush currents and even control the amount of current passing to the application. This enables power management and inrush current limitation in a single device. To reduce footprint and costs a balance between losses and cost-price on one side and electromagnetic interference on the other side is sought and an optimum switching frequency is chosen. To reduce cost and copper usage, switching happens on a high frequency of 300kHz. This increases the switching losses but greatly reduces the inductor size and cost compared to switching supplies running on lower frequencies. Additional filter circuits like snubbers are necessary to keep the control signals and therefore the output current stable.
Arsenic contamination of groundwater is a major public health concern worldwide. The problem has been reported mainly in southern Asia and, especially, in Bangladesh. Slow-sand filters (SSF) augmented with iron were proven to be a simple, low-cost and decentralized technique for the treatment of arsenic-contaminated sources. In this research, three pilot-scale SSF (flowrate 6 L·h−1) were tested regarding their capability of removing arsenic from groundwater in conditions similar to those found in countries like Bangladesh (70 µg As(III) L−1, 26 °C). From the three, two filters were prepared with mixed media, i.e., sand mixed with corrosive iron matter (CIM filter) and iron-coated sand (ICS filter), and a third conventional SSF was used as a reference. The results obtained showed that the CIM filter could remove arsenic below the World Health Organization (WHO) guideline concentration of 10 µg·L−1, even for inlet concentrations above 150 µg·L−1. After 230 days of continuous operation the arsenic concentration in the effluent started increasing, indicating depletion or saturation of the CIM layer. The effluent arsenic concentration, however, never exceeded the Bangladeshi standard of 50 µg·L−1 throughout the whole duration of the experiments.
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Social networks and news outlets use recommender systems to distribute information and suggest news to their users. These algorithms are an attractive solution to deal with the massive amount of content on the web [6]. However, some organisations prioritise retention and maximisation of the number of access, which can be incompatible with values like the diversity of content and transparency. In recent years critics have warned of the dangers of algorithmic curation. The term filter bubbles, coined by the internet activist Eli Pariser [1], describes the outcome of pre-selected personalisation, where users are trapped in a bubble of similar contents. Pariser warns that it is not the user but the algorithm that curates and selects interesting topics to watch or read. Still, there is disagreement about the consequences for individuals and society. Research on the existence of filter bubbles is inconclusive. Fletcher in [5], claims that the term filter bubbles is an oversimplification of a much more complex system involving cognitive processes and social and technological interactions. And most of the empirical studies indicate that algorithmic recommendations have not locked large segments of the audience into bubbles [3] [6]. We built an agent-based simulation tool to study the dynamic and complex interplay between individual choices and social and technological interaction. The model includes different recommendation algorithms and a range of cognitive filters that can simulate different social network dynamics. The cognitive filters are based on the triple-filter bubble model [2]. The tool can be used to understand under which circumstances algorithmic filtering and social network dynamics affect users' innate opinions and which interventions on recommender systems can mitigate adverse side effects like the presence of filter bubbles. The resulting tool is an open-source interactive web interface, allowing the simulation with different parameters such as users' characteristics, social networks and recommender system settings (see Fig. 1). The ABM model, implemented in Python Mesa [4], allows users to visualise, compare and analyse the consequence of combining various factors. Experiment results are similar to the ones published in the Triple Filter Bubble paper [2]. The novelty is the option to use a real collaborative-filter recommendation system and a new metric to measure the distance between users' innate and final opinions. We observed that slight modifications in the recommendation system, exposing items within the boundaries of users' latitude of acceptance, could increase content diversity.References 1. Pariser, E.: The filter bubble: What the internet is hiding from you. Penguin, New York, NY (2011) 2. Geschke, D., Lorenz, J., Holtz, P.: The triple-filter bubble: Using agent-based modelling to test a meta-theoretical framework for the emergence of filter bubbles and echo chambers. British Journal of Social Psychology (2019), 58, 129–149 3. Möller, J., Trilling, D., Helberger, N. , and van Es, B.: Do Not Blame It on the Algorithm: An Empirical Assessment of Multiple Recommender Systems and Their Impact on Content Diversity. Information, Communication and Society 21, no. 7 (2018): 959–77 4. Mesa: Agent-based modeling in Python, https://mesa.readthedocs.io/. Last accessed 2 Sep 2022 5. Fletcher, R.: The truth behind filter bubbles: Bursting some myths. Digital News Report - Reuters Institute (2020). https://reutersinstitute.politics.ox.ac.uk/news/truth-behind-filter-bubblesbursting-some-myths. Last accessed 2 Sep 2022 6. Haim, M., Graefe, A, Brosius, H: Burst of the Filter Bubble?: Effects of Personalization on the Diversity of Google News. Digital Journalism 6, no. 3 (2018): 330–43.
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Mondkapjes, of mondmaskers, zijn door de SARS-COV-2 pandemie niet meer uit het straatbeeld weg te denken. De kwaliteit en comfort van de pasvorm van medische en niet-medische mondmaskers wordt bepaald door hoe goed het mondmasker overeenkomt met de afmetingen van het gezicht van de drager. Echter is er geen goed overzicht van de antropometrie van het gelaat van de Nederlandse bevolking waardoor de pasvorm van mondmaskers nu vaak niet optimaal is. Er is dus vraag naar een laagdrempelige en veilige manier om gezichtskenmerken in kaart te brengen en betere ontwerprichtlijnen voor mondkapjes. Driedimensionaal (3D) scannen doormiddel van Light Detection and Ranging (LiDaR) technologie in combinatie met slimme algoritmes lijkt wellicht een manier om gezichtskenmerken snel en laagdrempelig vast te leggen bij grote groepen mensen. Daarnaast geeft het 3D scannen van gezichten de mogelijkheid om niet enkel de afmetingen van gezichten te meten, maar ook 3D pasvisualisaties uit te voeren. Hoewel 3D scannen geen nieuwe technologie is, is de LiDaR technologie pas sinds 2020 geïntegreerd in de Ipad en Iphone waardoor het toegankelijk gemaakt is voor consumenten. Doormiddel van een research through design benadering zal onderzocht worden of deze technologie gebruikt kan worden om betrouwbare en valide opnames te maken van gezichten en of er op basis hiervan ontwerprichtlijnen ontwikkeld kunnen worden. In dit KIEM GoCi-project zal daarnaast ingezet worden om een kennisbasis en netwerk op te bouwen voor een vervolg aanvraag over de inzet van 3D technologieën in de mode-industrie.
There are many digital tools and online agendas that try to help people in getting a clear overview of the cultural events and venues available in their city. They generate an overview which is quite suitable for finding commercial, mainstream entertainment events but most of the time they lack the ‘in depth’ content. As such, they are quite ‘generic’ and overlook the niches and specific sub-genres that define the heart of the cultural sector of a city (and match the individual preferences of the consumer). On the other hand, larger cities, with more than 100.000 inhabitants, may have websites or apps that counter this mainstream approach but tend to be too ‘cultural’, in the sense that they focus on artistic niche cultures or on specific events for very small target audiences. Both approaches make it challenging for (starting) artists to reach their potential audiences in a structural way and in that sense ‘valorise’ their content. A combination of those approaches could work, but that leads to the problem of overchoice, and requires a better filtering system. The “Just What I Want project” aims to bridge this gap in approach and uses the knowledge of experienced parties like the Groningen Night Mayor and the conclusions that were drawn after 3 years of the existence of the Here & Now in Groningen platform to generate a new form of cultural participation. This participation is intended to suit a wide variety of audiences and their potential events as well as venues and the audience that they search for.
There are many digital tools and online agendas that try to help people in getting a clear overview of the cultural events and venues available in their city. They generate an overview which is quite suitable for finding commercial, mainstream entertainment events but most of the time they lack the ‘in depth’ content. As such, they are quite ‘generic’ and overlook the niches and specific sub-genres that define the heart of the cultural sector of a city (and match the individual preferences of the consumer). On the other hand, larger cities, with more than 100.000 inhabitants, may have websites or apps that counter this mainstream approach but tend to be too ‘cultural’, in the sense that they focus on artistic niche cultures or on specific events for very small target audiences. Both approaches make it challenging for (starting) artists to reach their potential audiences in a structural way and in that sense ‘valorise’ their content. A combination of those approaches could work, but that leads to the problem of overchoice, and requires a better filtering system. The “Just What I Want project” aims to bridge this gap in approach and uses the knowledge of experienced parties like the Groningen Night Mayor and the conclusions that were drawn after 3 years of the existence of the Here & Now in Groningen platform to generate a new form of cultural participation. This participation is intended to suit a wide variety of audiences and their potential events as well as venues and the audience that they search for.
