Impacts of Personalized Sensor Feedback Regarding Exposure to Environmental Stressors

Feedback on personal exposure to air pollution, noise or extreme temperatures through wearable sensors or sensors installed at home or in the workplace can offer information that might motivate behaviours to mitigate exposure. As personal measurement devices are becoming increasingly accessible, it is important to evaluate the effects of such sensors on human perception and behaviour. We conducted a systematic literature research and identified 33 studies, analysing the effects of personal feedback on air pollution, noise and temperatures. Feedback was given through reports including different forms of visualization, in-person or over the telephone, or directly on the sensor or through a phone app. The exposure feedback led to behaviour changes particularly for noise and temperature feedback while findings on behaviour adaptation to avoid air pollution were mixed. Most studies reported increased awareness and knowledge from receiving exposure feedback. Many participants in studies on air pollution reported low levels of self-efficacy regarding exposure mitigation. For a better understanding of the effects of personal exposure feedback, more studies are required, particularly providing feedback from wearable sensors measuring outdoor air pollution, noise and temperature.

The Transient Reactor Test Facility (TREAT)

Constructed in the late 1950s, the Transient Reactor Test facility (TREAT) provided numerous transient irradiations until operation was suspended in 1994. It was later refurbished, and resumed operations in 2017 to meet the data needs of a new era of nuclear fuel safety research. TREAT uses uranium oxide dispersed in graphite blocks to yield a core that affords strong negative temperature feedback. Automatically controlled, fast-acting transient control rods enable TREAT to safely perform extreme power maneuvers—ranging from prompt bursts to longer power ramps—to broadly support research on postulated accidents for many reactor types. TREAT’s experiment devices work in concert with the reactor to contain specimens, support in situ diagnostics, and provide desired test environments, thus yielding a uniquely versatile facility. This chapter summarizes TREAT’s design, history, current efforts, and future endeavors in the field of nuclear-heated fuel safety research.

Study on Temperature Feedback Effect of Supercritical CO2–Cooled Reactor

As a potential new-type reactor, the supercritical CO2 (S-CO2)–cooled reactor has several advantages, such as being a simple system, having high thermal efficiency, having a small size, and being lightweight. Due to the poor neutronics moderation performance, the S-CO2–cooled reactor shows the disadvantage of a weak temperature feedback effect on reactivity. In this article, the neutronics performance of the reactor has been focused on, and the effects of temperature feedback on fuel, coolant, and moderator studied and the method to improve temperature feedback of the S-CO2 reactor proposed.

Development of a control system to maintain steady transition boiling

Steady transition boiling offers opportunities to observe fluid behavior and to measure transient and local heat flux as the surface dries and wets. This report discusses temperature control in transition boiling. Each component in the control system is either measured or estimated, and the controller parameters are determined along with the optimum depth of the temperature feedback point. Experiments are performed to verify the theoretical stability limit.

The amplification of Madden-Julian Oscillation boosted by temperature feedback

Due to small Coriolis force in tropics, the theoretical study of Madden-Julian Oscillation (MJO) often assumes weak temperature gradient balance, which neglects the temperature feedback (manifested in temperature tendency term). In this study, the effect of the temperature feedback on the MJO is investigated by using the MJO trio-interaction model, which can capture the essential large-scale features of the MJO.The scale analysis indicates that the rotation effect is strong for the MJO scales, so that the temperature feedback is as import as the moisture feedback (manifested in moisture tendency term), the latter is often considered to be critical for MJO. The experiments with the theoretical model show that the temperature feedback has significant impact on the MJO’s maintenance. When the temperature feedback is turned off, the simulated MJO cannot be maintained over the warm pool. This is because the temperature feedback could boost the energy generation. Without temperature feedback, only the latent heat can be generated. With temperature feedback, not only the latent heat but also the enthalpy (and therefore the available potential energy) can be generated. Therefore, the total energy generation is more efficient with temperature feedback, favoring the self-maintenance of the MJO. Further investigation shows that this effect of the temperature feedback on MJO amplification can be inferred from observations.The findings here indicates that the temperature feedback could have non-negligible impacts on MJO, and have implications in the simulation of MJO.

Changes in poleward atmospheric energy transport over a wide range of climates: Energetic and diffusive perspectives and a priori theories

The midlatitude poleward atmospheric energy transport increases in radiatively forced simulations of warmed climates across a range of models from comprehensive coupled general circulation models (GCMs) to idealized aquaplanet moist GCMs to diffusive moist energy balance models. These increases have been rationalized from two perspectives. The energetic (or radiative) perspective takes the atmospheric energy budget and decomposes energy flux changes (radiative forcing, feedbacks, or surface fluxes) to determine the energy transport changes required by the budget. The diffusive perspective takes the net effect of atmospheric macroturbulence to be a diffusive energy transport down-gradient, so a change in transport can arise from changes in mean energy gradients or turbulent diffusivity. Here, we compare these perspectives in idealized moist, gray-radiation GCM simulations over a wide range of climate states. The energetic perspective has a dominant role for radiative forcing in this GCM, with cancellation between the components of the temperature feedback that can account for the GCM's non-monotonic energy transport changes. Comprehensive CMIP5 GCM simulations have similarities in the northern hemisphere to the idealized GCM, though a comprehensive GCM over several CO2 doublings has a distinctly different feedback structure evolution. The diffusive perspective requires a non-constant diffusivity to account for the idealized GCM-simulated changes, with important roles for the eddy velocity, dry static stability, and horizontal energy gradients. Beyond diagnostic analysis, GCM-independent a priori theories for components of the temperature feedback are presented that account for changes without knowledge of a perturbed climate state, suggesting that this is the more parsimonious perspective.

Compact Modeling of a 3.3 kV SiC MOSFET Power Module for Detailed Circuit-Level Electrothermal Simulations Including Parasitics

In this paper, an advanced electrothermal simulation strategy is applied to a 3.3 kV silicon carbide MOSFET power module. The approach is based on a full circuital representation of the module, where use is made of the thermal equivalent of the Ohm’s law. The individual transistors are described with subcircuits, while the dynamic power-temperature feedback is accounted for through an equivalent thermal network enriched with controlled sources enabling nonlinear thermal effects. A synchronous step-up DC-DC converter and a single-phase inverter, both incorporating the aforementioned power module, are simulated. Good accuracy was ensured by considering electromagnetic effects due to parasitics, which were experimentally extracted in a preliminary stage. Low CPU times are needed, and no convergence issues are encountered in spite of the high switching frequencies. The impact of some key parameters is effortlessly quantified. The analysis witnesses the efficiency and versatility of the approach, and suggests its adoption for design, analysis, and synthesis of high-frequency power converters in wide-band-gap semiconductor technology.