Author Correction: A disconnect in science and practitioner perspectives on heat mitigation
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Full recovery of brines at normal temperature with process-heat-supplied coupled air-carried evaporating separation (ACES) cycle
Conventional air-carried evaporating separation (ACES) technology, to achieve complete separation and recovery of water and salt in brine, tends to necessitate heating air above a critical temperature (typically>90 °C). In this paper, a novel concept of process-heat-supplied and an ACES cycle with this technique is proposed. A comprehensive thermodynamic analytical investigation is conducted. The results indicate that at heat source supply temperature Tsupply of only 45.17 °C, this novel unit is capable of achieving complete separation of water and salt from 5 wt% concentration brine. Meanwhile, thermodynamic mechanism analysis reveals that sufficient process-heat-supplied affords the fluid self-adaptive regulation on the driving potential of heat and mass transfer, thus circumventing traditional heat and mass transfer limitation. Additionally, a solar ACES system with process-heat-supplied incorporating heat pump is further proposed. For this system, theoretical evaporation rate for unit area of solar irradiation me-solar = 2.23 kg/(m2·h), integrated solar utilization efficiency ηi = 188%; while considering overall losses me-solar = 1.41 kg/(m2·h), ηi = 95.2%.
Multi-sectoral efforts are required for decarbonising the building sector: a case in Hong Kong
Decarbonising the building sector involves collaborative efforts from multiple sectors. Previous studies only focused on carbon mitigation within individual measures, impeding the interconnections within various stages, contributing sectors, and measures. We propose an innovative “stage-sector-measure” framework for evaluating the carbon mitigation effects of the building sector and apply it to Hong Kong. Results show carbon emissions of Hong Kong’s building sector will decrease by 84.4% in 2050. Electricity is the most significant contributing sector, accounting for 71.8% of accumulative mitigation effects of Hong Kong’s building sector. Regarding measures, cleaner production of concrete and steel represents 62.9% of mitigation effects in material production stage, while alternative fuel mix and carbon capture and storage account for 42.2–87.7% of those in other stages. By clarifying the relationships among the stages, contributing sectors, and measures, we identify the mitigation mechanism of the building sector and reveal the significance of multi-sectoral efforts in its decarbonisation.
Noise-agnostic quantum error mitigation with data augmented neural models
Quantum error mitigation, a data processing technique for recovering the statistics of target processes from their noisy version, is a crucial task for near-term quantum technologies. Most existing methods require prior knowledge of the noise model or the noise parameters. Deep neural networks have the potential to lift this requirement, but current models require training data produced by ideal processes in the absence of noise. Here we build a neural model that achieves quantum error mitigation without any prior knowledge of the noise and without training on noise-free data. To achieve this feature, we introduce a quantum augmentation technique for error mitigation. Our approach applies to quantum circuits and to the dynamics of many-body and continuous-variable quantum systems, accommodating various types of noise models. We demonstrate its effectiveness by testing it both on simulated noisy circuits and on real quantum hardware.
Risks of competing discourses of scientific responsibility in global ocean futures
Accelerated innovation in climate-impacted oceans is outpacing standards of scientific responsibility. Standards of responsibility are critical because they shape research agendas, funding flows, scientific practice, and how innovations are regulated. Here, we examine responsibility debates among 243 marine scientists and end-users proposing, trialling and/or implementing 76 innovations for climate-impacted oceans. We identify three distinct discourses: ‘science outside society’, ‘science for society’ and ‘science with society’. Competition within and across these discourses reveals heightened tensions between the need to protect scientific autonomy and freedom, and moral duty to ensure socially just and desirable ocean futures. Without thorough debate and oversight, the wide-reaching power of such unresolved tensions could propel marine science and ocean futures into volatile ethical and moral territory. Better connection and articulation of standards of responsibility with scientific motivations, practices, and funding are key to ensuring the transparency and accountability required to progress equitable and sustainable oceans.
Universal relations and bounds for fluctuations in quasistatic small heat engines
The efficiency of any heat engine, defined as the ratio of average work output to heat input, is bounded by Carnot’s celebrated result. However, this measure is insufficient to characterize the properties of miniaturized heat engines carrying non-negligible fluctuations, and a study of higher-order statistics of their energy exchanges is required. Here, we generalize Carnot’s result for reversible cycles to arbitrary order moment of the work and heat fluctuations. Our results show that, in the quasistatic limit, higher-order statistics of a small engine’s energetics depend solely on the ratio between the temperatures of the thermal baths. We further prove that our result for the second moment gives universal bounds for the ratio between the variances of work and heat for quasistatic cycles. We test this theory with our previous experimental results of a Brownian Carnot engine and observe the consistency between them, even beyond the quasistatic regime. Our results can be exploited in the design of thermal nanomachines to reduce their fluctuations of work output without marginalizing its average value and efficiency.
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