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Establishing the correlation between damage recovery and temperature in nuclear materials is vital to understanding material property degradation. Among the handful of topics related, one long-standing concern is the differences in damage recovery caused by different initial defect concentrations, with respect to ranges below and beyond the damage saturation limit. In this study, the temperature dependence of damage recovery has been comprehensively elucidated for pure tungsten, irradiated with 6 MeV copper ions at room temperature (RT), up to 0.05 dpa (non-saturated damage, n-SD) and 0.6 dpa (saturated damage, SD), and followed by isochronal annealing. Coupled transmission electron microscopy and Doppler broadening positron annihilation spectroscopy characterizations provided a full-probe-range picture of defect evolution. The varied initial defect concentrations caused retaining differences in damage recovery, but no substantial influence on temperature-dependent defect evolution. Moderate and dramatic damage recovery were identified below 973 K and above 1123 K in n-SD and SD tungsten, respectively. Most strikingly, nano-sized voids were confirmed at 473 K in both samples. Annealing at 1873 K saw the complete removal of defects in n-SD tungsten, but survival of a few dislocations via void pinning in SD tungsten. Full damage recovery in SD tungsten was projected to be ∼2000 K. The current revisit of damage recovery stages demonstrated the significance of encompassing scenarios of non-saturated and saturated defect concentrations. Accordingly, four damage recovery stages were redefined for heavy-ion irradiated tungsten, namely stage I (20 K–RT), stage II (RT–653 K), stage III (653–1123 K), and stage IV (1123–2000 K). [Display omitted] [ABSTRACT FROM AUTHOR]

Extreme temperatures are becoming increasingly common due to global warming. Extreme cold and heat events lead to an increase in mortality rates. More deaths occur in cold weather as a result of hypothermia. However, the change progress of body core temperature and the survival time during cold exposure has yet to be extensively studied. To establish a mathematical thermoregulatory model for prolonged cold air exposure and to propose a method for predicting survival time under sedentary conditions. We extended the classical multi-segment multi-node human thermoregulatory model by considering the effects of thermoregulatory fatigue on shivering and vasoconstriction based on the variable setpoint theory. The core threshold temperatures and the sensitivity of the responses decreased with the degree of fatigue (fa). The model was then used to systematically examine the effects of environmental parameters on the time course of body core temperature in the development of fatal hypothermia. A new wind chill index was constructed based on the simulated data of our thermoregulatory model to estimate the survival time. Our extended thermoregulatory model predicted that during prolonged cold air exposures, body core temperature would decrease in three distinct stages: an initial decrease due to uncompensated cooling load, an equilibrium plateau due to shivering, and a final rapid drop due to thermoregulatory fatigue. Fatal hypothermia occurred at the third stage due to impaired shivering and vasoconstriction caused by fatigue. Lower air temperature and higher air speed can accelerate the occurrence of hypothermia. We proposed a predictive equation for survival time, i.e., the maximum endurance time before fatal hypothermia occurs, which is an exponential function of the wind chill index, and the newly defined wind chill index considers the contribution from both air temperature and air speed. We suggest a new thermoregulatory model to predict the fatal hypothermia due to thermoregulatory fatigue during cold air exposure. We proposed a survival time chart based on a new wind chill index, which can be used to alert the early risk of fatal hypothermia during extreme cold events. [Display omitted] • Thermoregulatory fatigue is a dominant factor leading to hypothermia during cold exposure. • Thermoregulatory fatigue leads to attenuated shivering and vasoconstriction during cold exposure. • T core course consists of three stages: a slow decrease, an equilibrium plateau, and a rapid drop. • Survival time is an exponential function of the new wind chill index defined by T a and V a. • Thermoregulation modeling can be used to predict and early recognize the risk of hypothermia. [ABSTRACT FROM AUTHOR]

Considering transport applications, there is worldwide an increasing interest in the use of hydrogen-energy for supplying electric powertrains. In order to extend the fuel cell lifespan and to increase its reliability and efficiency, the following features are essential to a fuel cell stack connected DC/DC boost converter: low input current ripple, high voltage gain ratio, high efficiency, high compactness, and high redundancy. Moreover, in order to assess in real time the state-of-health of the fuel cell stack, on-line Electrochemical Impedance Spectroscopy (EIS) functionality integrated with the fuel cell stack connected DC/DC boost converter is a real promising solution requiring no additional measurement equipment. From these points of view, this paper presents a comparison analysis of high voltage gain DC/DC boost converters for fuel cell electric vehicles applications. In addition, some comments and guidelines regarding integration issues are also provided. • The development status of commercialized FCEVs has been generally studied. • Various techniques for FCEV DC/DC converter to gain high performance were compared. • Existed diagnostic methods of fuel cell were comparative studied. • Requirements of converter-based online fuel cell impedance detection were proposed. [ABSTRACT FROM AUTHOR]

Abstract Declining reserves of the crude oil and increasingly serious environmental pollution have emphasized the requirement of a suitable substitute to our actual petroleum-based automobile market. An environmentally-friendly and efficient power generation device based on a sustainable energy source is attractive to settle this issue and realize cleaner production. Proton Exchange Membrane Fuel Cell (PEMFC), which achieves zero emission, modular construction, high energy conversion ratio and etc., has been treated as one of the most promising solution for automobile applications. Nevertheless, many technical restrictions such as relatively short life cycle have still to be conquered before satisfying the requirements of large-scale commercialization. Electrochemical Impedance Spectroscopy (EIS) is an effective technique for fault detection of electrochemical system. This paper presents an on-line EIS detection strategy based on the proposed fuel cell stack connected step-up converter. No additional equipment is required compared with conventional detection process. Furthermore, the proposed 6-phase Interleaved Boost Converter (IBC) based on Silicon Carbide (SiC) semiconductors and inverse coupled inductors has achieved low input current ripple, high efficiency, high voltage gain ratio, high compactness and high redundancy. Benefiting from these advantages, the lifespan of fuel cell stack can be extended. The proposed online EIS detection has been realized and the results have been compared with theoretical analysis. Highlights • A six-phase interleaved boost converter based on silicon carbide semiconductor and inverse coupled inductor was proposed. • Online electrochemical impedance spectroscopy detection functionality was integrated with Sliding-Mode Control strategy. • Close loop control was realized even during the impedance detection processes. • The frequency range of impedance was from 1 Hz to 10 kHz. • The simulation results matched well with the theoretical results. [ABSTRACT FROM AUTHOR]