Exposure of FeCrAl Overlay Welds on Superheater Tubes: Influence of Local Environment on Degradation

Two experimental FeCrAl alloy overlay welds on tube shields were exposed in the superheater of a full-size waste fired boiler for 6 months. The tube shields were in different tube lines and positions within the superheater chamber to investigate possible heterogeneities in the exposure environment. The visual inspection of the exposed tube shields and the corrosion-erosion rates calculated from the analysis of cross-sections showed that the mid-length roof location experienced the most aggressive environment. The compositional differences between the two experimental alloys were not found to be determinant in their performance under these specific exposure conditions. It was concluded that erosion had a decisive influence on the results. The identification of local differences within the superheater chamber is important when deciding on the material selection for the different areas and locations to be protected. The output of this study is therefore interesting for further design consideration of superheaters as well as for future planning of exposures.

A Unified Switch Loss Model and Design Consideration for Multilevel Boost PFC With GaN Devices

Recently, multilevel converters with gallium nitride (GaN) devices have shown marvelous advantages for power factor correction (PFC) conversion to meet the increasingly higher efficiency and power density requirements. In the traditional design process for the multilevel PFC converter, it is necessary to separately optimize the devices of the corresponding breakdown voltage under different level number, which causes difficulty to the overall optimization of the entire system. In this paper, a unified minimum loss model for GaN switches regardless of voltage levels is proposed to optimize the efficiency based on device’s new figure-of-merit (NFoM) (NFoM = COSS(ER) RDS(on)). With the help of this unified minimum loss model, it simplifies the efficiency optimizing methodology according to the NFoMs of GaN devices for multilevel PFC converter. According to the methodology, a 2 kW cascaded H-bridge (CHB) PFC prototype is constructed to verify the design methodology, achieving over 99% efficiency with power density over 1000 W/in3 .

Subliminal Paradigmatic on Designing Character in Games

Not only rely on aesthetics alone, but character design also requires things that underlie decision making in the design process. The consideration may refer to the type of story, style and appearance that also refers to the form, which is part of the elements of design, but other than those designers must also be paid attention to other things that related with the problem that occurs when the game is played. Games will be played by players who in fact have experiences that will later be brought into the game and instead bring experience from within the game to the real world. This unconscious condition can also be used as a design consideration.

Is Someone Listening?

Smart devices with the capability to record audio can create a trade-off for users between convenience and privacy. To understand how users experience this trade-off, we report on data from 35 interview, focus group, and design workshop participants. Participants' perspectives on smart-device audio privacy clustered into the pragmatist, guardian, and cynic perspectives that have previously been shown to characterize privacy concerns in other domains. These user groups differed along four axes in their audio-related behaviors (for example, guardians alone say they often move away from a microphone when discussing a sensitive topic). Participants surfaced three usage phases that require design consideration with respect to audio privacy: 1) adoption, 2) in-the-moment recording, and 3) downstream use of audio data. We report common design solutions that participants created for each phase (such as indicators showing when an app is recording audio and annotations making clear when an advertisement was selected based on past audio recording).

Chaos in small microbial communities

Predictability is a fundamental requirement in biological engineering. As we move to building coordinated multicellular systems, the potential for such systems to display chaotic behaviour becomes a concern. Therefore understanding which systems show chaos is an important design consideration. We developed a methodology to explore the potential for chaotic dynamics in small microbial communities governed by resource competition, intercellular communication and competitive bacteriocin interactions. We show that we can expect to find chaotic states in relatively small synthetic microbial systems, understand the governing dynamics and provide insights into how to control such systems. This work is the first to query the existence of chaotic behaviour in synthetic microbial communities and has important ramifications for the fields of biotechnology, bioprocessing and synthetic biology.