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  1. Abstract Metal foam is light in weight and exhibits an excellent impact-absorbing capability. Laser forming has emerged as a promising process in shaping metal foam plates into desired geometry. While the feasibility and shaping mechanism has been studied, the effect of the laser forming process on the mechanical properties and the energy-absorbing behavior in particular of the formed foam parts has not been well understood. This study comparatively investigated such effect on as-received and laser-formed closed-cell aluminum alloy foam. In quasi-static compression tests, attention paid to the changes in the elastic region. Imperfections near the laser-irradiated surface were closely examinedmore »and used to help elucidate the similarities and differences in as-received and laser-formed specimens. Similarly, from the impact tests, differences in deformation and specific energy absorption were focused on, while relative density distribution and evolution of foam specimens were numerically investigated.« less
    Free, publicly-accessible full text available January 1, 2023
  2. “Notice and choice” is the predominant approach for data privacy protection today. There is considerable user-centered research on providing efective privacy notices but not enough guidance on designing privacy choices. Recent data privacy regulations worldwide established new requirements for privacy choices, but system practitioners struggle to implement legally compliant privacy choices that also provide users meaningful privacy control. We construct a design space for privacy choices based on a user-centered analysis of how people exercise privacy choices in real-world systems. This work contributes a conceptual framework that considers privacy choice as a user-centered process as well as a taxonomy formore »practitioners to design meaningful privacy choices in their systems. We also present a use case of how we leverage the design space to fnalize the design decisions for a real-world privacy choice platform, the Internet of Things (IoT) Assistant, to provide meaningful privacy control in the IoT.« less
  3. Browser users encounter a broad array of potentially intrusive practices: from behavioral profiling, to crypto-mining, fingerprinting, and more. We study people’s perception, awareness, understanding, and preferences to opt out of those practices. We conducted a mixed-methods study that included qualitative (n=186) and quantitative (n=888) surveys covering 8 neutrally presented practices, equally highlighting both their benefits and risks. Consistent with prior research focusing on specific practices and mitigation techniques, we observe that most people are unaware of how to effectively identify or control the practices we surveyed. However, our user-centered approach reveals diverse views about the perceived risks and benefits, andmore »that the majority of our participants wished to both restrict and be explicitly notified about the surveyed practices. Though prior research shows that meaningful controls are rarely available, we found that many participants mistakenly assume opt-out settings are common but just too difficult to find. However, even if they were hypothetically available on every website, our findings suggest that settings which allow practices by default are more burdensome to users than alternatives which are contextualized to website categories instead. Our results argue for settings which can distinguish among website categories where certain practices are seen as permissible, proactively notify users about their presence, and otherwise deny intrusive practices by default. Standardizing these settings in the browser rather than being left to individual websites would have the advantage of providing a uniform interface to support notification, control, and could help mitigate dark patterns. We also discuss the regulatory implications of the findings.« less
  4. This work focuses on fabrication of multi-hollow polyimide gel and aerogel particles from a surfactant-free oil-in-oil emulsion system using a microfluidic droplet generator operating under dripping mode. The multi-hollow gel and aerogel particles have strong potential in thermal insulation. Under jetting and tip-streaming regime of microfluidic flows, droplets are generated with no occluded liquid phase. The present study investigates a means of designing polyimide gel particles with plurality of internal liquid droplets by strategically manipulating the flow rates of the continuous and dispersed phase liquids through the microfluidic droplet generator. The multi-hollow polyimide aerogel particles obtained after supercritical drying ofmore »the gel particles present mesopores, high BET surface area, and excellent prospect for thermal insulation.« less
  5. Increasingly, icons are being proposed to concisely convey privacyrelated information and choices to users. However, complex privacy concepts can be difcult to communicate. We investigate which icons efectively signal the presence of privacy choices. In a series of user studies, we designed and evaluated icons and accompanying textual descriptions (link texts) conveying choice, opting-out, and sale of personal information — the latter an opt-out mandated by the California Consumer Privacy Act (CCPA). We identifed icon-link text pairings that conveyed the presence of privacy choices without creating misconceptions, with a blue stylized toggle icon paired with “Privacy Options” performing best. Themore »two CCPA-mandated link texts (“Do Not Sell My Personal Information” and “Do Not Sell My Info”) accurately communicated the presence of do-notsell opt-outs with most icons. Our results provide insights for the design of privacy choice indicators and highlight the necessity of incorporating user testing into policy making.« less
  6. Abstract Metal foam sandwich panels have been the subject of many concept studies, due to their exceptional stiffness, light weight, and crash absorption capacity. Yet, the industrial production of the material has been hampered by the fact that it is challenging to bend the material into practical engineering shapes. Only recently, it has been shown that bending of metal foam sandwich panels is possible using lasers. It was also shown that the material can be bent into Euclidean (2D) geometries, and the governing laser-induced bending mechanisms were analyzed. This study was focused on laser forming of metal foam sandwich panelsmore »into non-Euclidean (3D) geometries. It was investigated whether the bending mechanisms and process parameters identified for 2D laser forming translate to 3D deformation. Additionally, the impact of the laser scan length was determined by comparing different scan patterns that achieve the same 3D geometries. It was shown that laser forming could induce 3D deformation necessary for both bowl and saddle shapes, the two fundamental non-Euclidean geometries. The amount of laser-induced bending and in-plane strains vary depending on process conditions and the governing bending mechanisms. Lastly, the laser scan length was shown to become more important for metal foam sandwich panels, where the panel thickness tends to be large.« less