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Youth digital well-being:The role of digital skills and positive and negative digital outcomes in youth's subjective well-being
Get PDFDigital inequality research has shown considerable variation in individuals' ability to leverage the internet for personal benefit and well-being. However, the role of negative digital outcomes remains underexplored. Furthermore, there has been little research outside Western countries on this topic. This study investigates the relationship between digital skills and both positive and negative digital outcomes, and their impact on subjective well-being (SWB) among youth in Indonesia. We also explore the role of age, gender, education level, and subjective social class in this context. Using a survey among 1250 respondents aged 16–30 in Jakarta, we found a strong effect of digital skills on SWB, stronger than any other effect in our study. Positive and negative digital outcomes were also linked to SWB. Moreover, digital skills showed indirect effects on SWB through both positive and negative digital outcomes. SES factors such as education level and subjective social class did not directly affect SWB. These structural conditions had a weak effect on digital skills, and no significant indirect effect on SWB was observed. These findings underscore the crucial role of digital inequality variables as “new” sources of inequality, which influence youth's SWB. The prominent role of digital skills and weak relations with the structural conditions create opportunities to improve SWB and address digital inequality. Therefore, policy and intervention efforts should prioritize enhancing the digital skills of young people, especially those from disadvantaged backgrounds. This can be done through various learning programs (online and offline), particularly informal education that fosters positive digital outcomes while mitigating potential negative impacts on their well-being.</p
Identifying Physical Interactions in Contact-Based Robot Manipulation for Learning from Demonstration
No full textIdentifying physical interactions between a robot and its environment can improve autonomous robot manipulation. Methods in the literature can identify meaningful physical interactions, such as constraints, from a single task demonstration. However, they do not scale well when a wide variety of different physical interactions may be encountered. To alleviate this limitation, this work proposes to model physical interactions with interaction frames: reference frames that attach to the robot and/or ground body and have interaction classes associated with each axis. Interaction frames are identified by minimizing and decoupling the Cartesian mechanical power components in demonstration data. Thereby, interaction frames identify what interactions take place where, for example at geometric features. The method is evaluated in three experiments. First, identification accuracy is evaluated through several single-constraint experiments comparing velocity-based, force-based, and the proposed power-based method, where the latter is found to be advantageous. Second, the method is applied to a task demonstration that contains different sequential contacts. Third, it is illustrated how the method can be used as a basis for Learning from Demonstration, by reproducing the sequential task from a single demonstration. The method can be applied with little prior information, to advance the development of versatile robots
Concentrating on cakes:PFAS removal from reverse osmosis concentrate using cake filtration
No full textThe pollution of water resources by man-made chemicals is increasing the already stressed supply of clean drinking water. One type of chemicals that got a lot of attention over the last 20 years are so-called "per- and polyfluoroalkyl substances", more commonly referred to as PFAS. To produce drinking water with PFAS levels below regulatory norms, many current water treatment facilities have to be modified. The subsequent treatment of water by first using reverse osmosis membranes and then adsorption with activated carbon, is an already conventional water treatment method. In this thesis the simultaneous (instead of subsequent) treatment of water by reverse osmosis and adsorption is investigated. This is accomplished by introducing the adsorption step in the recirculation of a closed circuit reverse osmosis process. The adsorption is performed in a filter cake to be able to keep the hydraulic resistance of the adsorbent layer low. A proper evaluation of this process requires that each of the components: therefore adsorption of PFAS, cake filtration, adsorption in a filter cake and combined operation are investigated.In Chapter 1 motivation, scientific and regulatory context for the thesis are given. Chapter 2 discusses the usage of various bio-based materials as adsorbents for PFAS and compares them to conventional activated carbon. Chapter 3, the transient description of cake filtration experiments in a vertical filter vessel is shown. In Chapter 4, the influence of the formation of an adsorption bed by cake filtration on its subsequent use as an adsorbent bed for PFAS is discussed. Subsequently, these elements are combined in Chapter 5 which describes the simultaneous closed circuit reverse osmosis adsorption treatment for scaling prone water to increase water recovery and remove PFAS. Finally in Chapter 6 the results are summarized and reflected on.<br/
Strong piezoelectric-like electromechanical response from single granular PMMA interface
No full textEnergy harvesting devices, namely triboelectric nanogenerators (TENGs) and piezoelectric nanogenerators (PENGs), are rapidly garnering interest. As such, a great deal of research is devoted to developing electromechanically responsive materials, particularly flexible polymers. State-of-the-art materials are typically made from toxic fluoropolymers, which need to be avoided due to environmental contamination risks. In this work, we investigate the electromechanical response of a granular-based electromechanical device. Close-packed monolayers comprising polymethyl methacrylate (PMMA) beads with diameters of 0.5 or 3.0 μm are assembled using a solvent-free rubbing method. Subsequently, the ordered monolayers are brought into contact, while a force is cyclically applied in a quasi-static mode and during buzzer testing. The beads enable the production of ultra-thin polymer layers (with a combined thickness of only 3.5 μm) with controlled morphology (Set by the bead size), which is highly challenging for other polymers. Our findings show that we achieve a d33 value of 19 (in quasi-static mode) and 117 pC/N (buzzer test) for the granular-based PMMA electromechanical device, elucidating the great potential of such beads in mechanical energy harvesting devices, as it matches and outperforms most state-of-the-art polyvinylidene fluoride (PVDF) piezoelectric materials
A novel cleanroom-free technique for simultaneous electrodeposition of polypyrrole onto array of IDuEs:Towards low-cost, stable and accurate point-of-care TBI diagnosis without trained manpower
No full textDrop-casted polypyrrole (PPY) nanomaterial-based point-of-care Traumatic Brain Injury (TBI) immunosensing platforms reported previously demand trained manpower at field-test, due to poor adhesion between nanomaterial and electrode surface, limiting the point-of-care purpose. The usage of conventional clean-room-based physical and chemical vapor deposition techniques in creating strong adhesion is limited on account of cost and process complexity. Addressing this technical gap, we report a novel low-cost clean-room-free technique that can effectively electrodeposit the PPY simultaneously onto the working areas of array of Interdigitated microelectrodes (IDμEs) from the precursor solution. Through optimization of deposition cycles and molar concentration ratio of monomer and oxidizing agents, a high-quality nanomaterial was electrodeposited on IDμEs' surface. Further, by using the electrodeposited PPY as a bioelectrical transducer, the TBI-specific UCHL1 and GFAP target analytes were simultaneously detected in terms of variation of DC-Resistance and AC-Capacitance parameters, recorded through chemiresistive I-V and chemicapacitive C-F responses of bioelectrodes, respectively. Such simultaneous multianalyte-detection in terms of multiple parameters increases the diversity of decision-making parameters by several folds, inherently aids in enhancing the diagnostic accuracy of TBI test kit. Here, the efficiency of the electrodeposited PPY-based chemiresistive and chemicapacitive immunosensing platforms in detecting TBI-specific target analytes simultaneously in real-time human-plasma samples was analyzed in terms of sensitivity, resolution, LoD, RoD, long-term stability (30 weeks), and the same is compared with drop-cast PPY-based immunosensing platform. Notably, the electrodeposited PPY sensing platforms showed superior performance in terms of sensitivity, LoD, device variability and long-term stability without demanding any trained manpower in the field.</p
Attention- and action-related oscillatory dynamics in a visuomotor network
Get PDFA network model of a “selection-for-action” system was proposed with the primary idea that the functions of stimulus and response selection are carried out within a visuomotor oscillatory network. To examine the network’s dynamics under different sensorimotor demands, an electroencephalographic experiment was performed, contrasting visual detection and discrimination variants of a Posner cueing task. In the former, the required response can be prepared before target onset, whereas in the latter—only after target onset. Using the generalized eigenvalue decomposition method for EEG source isolation, we identified four network subcomponents: lateral motor, lateral visual, midfrontal, and midparietal sources. The local and inter-source activity relevant for spatial attention (visual and midparietal sources) were involved before target onset in both tasks but stronger for the discrimination task. The local activity and inter-source connectivity relevant for action control (motor and midfrontal sources) were involved before target onset only in the detection task. Importantly, in line with the model’s predictions, we observed that proactive response preparation in the detection task entailed beta-band connectivity between the response control areas and visual areas. Moreover, we observed a response-related spatial modulation of pre-target local visual alpha activity in the detection task. These results likely reflect automatic visuomotor integration.</p
Shark-inspired riblet design and optimization for drag reduction in drinking water distribution pipes across varying flow rates
No full textDrinking water distribution systems (DWDS) experience significant energy losses due to turbulence-induced drag. While shark-inspired riblet surfaces have been shown to reduce drag in controlled conditions, their effectiveness in DWDS remains uncertain, particularly under the dynamic flow variations. This experimental study explores biomimetic riblet designs as a potential solution for drag reduction in such environments. Two riblet configurations were evaluated: one designed after the shortfin mako shark (MSI), with smaller, tightly spaced riblets, and another based on the blacktip shark (BSI), with larger, widely spaced riblets. Riblet structures were 3D-printed and tested in a water flow loop system. The results show that although MSI and BSI achieved similar maximum drag reduction of approximately 6 % near a nondimensional spacing of s⁺ ≈ 14.5, their performance differed significantly versus Reynolds numbers. The MSI design sustained drag reduction over a wider range (2500 < Re < 20,000), while the BSI design was effective only within 2500 < Re < 8500. However, beyond these ranges, both designs began to experience drag increase. In addition, a comparison of geometric descriptors revealed that the square root of the groove cross-sectional area (lg+), provided the most consistent predictor for optimal riblet performance in pipe flow. However, the mean optimal value of lg+ was approximately 8.45, which is lower than the reference value of 10.7 reported for channel flows. This deviation likely results from confinement and curvature effects in pipe geometries, which modify vortex–riblet interactions compared to planar flows. These findings highlight the need to tailor riblet design to pipe-specific conditions and show that combining geometric and flow parameters improves performance evaluation in DWDS.</p
Advancing High-Frequency Inverter Design in More Electric Aircraft:Challenges and Research Perspectives
No full textThe transition toward aircraft electrification not only reduces the carbon footprint but also advances sustainable aviation, propelling the future of aviation with enhanced performance and system integration. In the realm of more electric aircraft (MEA), traditional hydraulic, pneumatic, and mechanical systems are being replaced by motor-driven electrical architectures. High-frequency inverters are essential for driving these motors at very high speeds (>100 kRPM). This article investigates the impact of the aviation environment on the design of high-frequency inverters, particularly considering the effects of low pressure, reduced air density, cosmic ray radiation, and a wide range of operating temperatures on semiconductor power devices and capacitive, resistive, and inductive components. The reduced air density at high altitudes makes cooling particularly challenging, highlighting the need for efficient thermal management systems. The study also explores electromagnetic interference, its generation and mitigation techniques while evaluating various pulsewidth modulation (PWM) technologies. Moreover, the article reviews the benefits and suitability of advanced multilevel inverter topologies for MEA applications. Finally, the article highlights the importance of innovative inverter topologies andPWM techniques that are better suited for MEA.</p