This study investigated monthly variations of surface urban heat island intensity (SUHII) and the applicability of the local climate zones (LCZ) scheme for land surface temperature (LST) ...differentiation within three spatial contexts, including urban, rural and their combination, in Shenyang, China, a city with a monsoon-influenced humid continental climate. The monthly SUHII and LST of Shenyang were obtained through 12 LST images, with one in each month (within the period between 2018 and 2020), retrieved from the Thermal InfraRed Sensor (TIRS) 10 in Landsat 8 based on a split window algorithm. Non-parametric analysis of Kruskal-Wallis H test and a multiple pairwise comparison were adopted to investigate the monthly LST differentiations with LCZs. Overall, the SUHII and the applicability of the LCZ scheme exhibited spatiotemporal variations. July and August were the two months when Shenyang underwent strong heat island effects. Shenyang underwent a longer period of cool than heat island effects, occurring from November to May. June and October were the transition months of cool–heat and heat–cool island phenomena, respectively. The SUHII analysis was dependent on the definition of urban and rural boundaries, where a smaller rural buffering zone resulted in a weaker SUHI or surface urban cool island (SUCI) phenomenon and a larger urban area corresponded to a weaker SUHI or SUCI phenomenon as well. The LST of LCZs did not follow a fixed order, where in July and August, the LCZ-10 (Heavy industry) had the highest mean LST, followed by LCZ-2 (Compact midrise) and then LCZ-7 (Lightweight low-rise). In comparison, LCZ-7, LCZ-8 (Large low-rise) and LCZ-9 (Sparsely built) had the highest LST from October to May. The LST of LCZs varied with urban and rural contexts, where LCZ-7, LCZ-8 and LCZ -10 were the three built LCZs that had the highest LST within urban context, while LCZ-2, LCZ-3 (Compact low-rise), LCZ-8, LCZ-9 and LCZ-10 were the five built LCZs that had the highest LST within rural context. The suitability of the LCZ scheme for temperature differentiation varied with the month, where from July to October, the LCZ scheme had the strongest capability and in May, it had the weakest capability. Urban context also made a difference to the suitability, where compared with the whole study area (the combination of urban and rural areas), the suitability of built LCZs in either urban or rural contexts weakened. Moreover, the built LCZs had a higher level of suitability in an urban context compared with a rural context, while the land-cover LCZs within rural had a higher level of suitability.
•This study frames heat injustice in aspects of cause-related, effect-related and process-related injustice.•Empirical survey was conducted in Yangtze River Delta and Chengdu-Chongqing urban ...agglomerations.•This study geographically revealed effect-related and process-related injustice in YRD and CCEC regions.•The cause-related, effect-related and process-related injustice depended on the socioeconomic factors.•Urban planning and design for heat-resilient cities and setting temporary shelters should be prioritised in heat actions.
Urban heat has affected numerous cities with increasingly severe environmental, social, economic, and health impacts. It is urgent to develop plans and take actions to beat the heat before cities are locked into unintended consequences. An understanding of heat injustice is important to support heat plans and actions for accurately alleviating heat-related risks and threats, scientifically avoiding unexpected conflicts and disputes, and actively driving citizens to participate in actual implementation. Existing studies have primarily focused on effect-related injustice (e.g., morbidity and mortality), while a systematic understanding of heat injustice is lacking. To overcome this research gap, this study framed heat injustice in terms of cause-related, effect-related, and process-related injustice, and empirically verified them based on a questionnaire survey in the Yangtze River Delta (YRD) and Chengdu-Chongqing Economic Circle (CCEC) regions. The survey results from 2704 respondents indicated that effect-related injustice and process-related injustice were geographically prominent in the YRD and CCEC regions. Socioeconomically, cause-related, effect-related, and process-related injustice occurred with the identification of groups who thought the heat was more severe were more susceptible to physiological and psychological impacts, and had lower levels of heat-related awareness and knowledge. The results also indicated that both YRD and CCEC regions should urgently develop heat action plans, which should be regionalized and group-specific. Urban planning and design for heat-resilient cities and setting temporary cooling shelters should be prioritized. Moreover, this study identified inconsistencies among higher levels of heat-related knowledge, lower levels of cooling strategy familiarity, and lower urgency of heat actions among the elderly, less educated, unhealthy, and wealthy groups. Overall, this study provides a reference for understanding heat injustice and formulating unbiased and implementable heat action plans.
Heat waves (HWs) and urban heat islands (UHIs) can potentially interact. The mechanisms behind their synergy are not fully disclosed. Starting from the localized UHI phenomenon, this study aims i) to ...reveal their associated impacts on human thermal comfort through three different definitions of HW events, based on air temperature (airT), wet-bulb globe temperature (WBGT) and human-perceived temperature (AppT) respectively, and ii) to understand the role of air moisture and wind. The analysis was conducted in four districts (NH, JD, MH and XJH) with different urban development patterns and geographic conditions, in the megacity of Shanghai with a subtropical humid climate.
Results evidenced the localized interplay between HWs and UHIs. The results indicate that less urbanized districts were generally more sensitive to the synergies. JD district recorded the highest urban heat island intensity (UHII) amplification, regardless of the specific HW definition. Notably, during AppT-HWs, the increment was observed in terms of maximum (1.3 °C), daily average (0.8 °C), diurnal (0.4 °C) and nocturnal UHII (1.0 °C). Nevertheless, localized synergies between HWs and UHIs at different stations also exhibited some commonalities. Under airT-HW, the UHII was amplified throughout the day at all stations. Under WBGT-HW, diurnal UHII (especially at 11:00–17:00 LST) was consistently amplified at all stations. Under AppT-HW conditions, the nocturnal UHII was slightly amplified at all stations. Air moisture and wind alleviated the synergistic heat exacerbation to the benefit of thermal comfort. The extent depended on geographic condition, diurnal and nocturnal scenarios, temperature type and HW/normal conditions. Stronger HW-UHI synergies indicate the necessity to develop specific urban heat emergency response plans, able to capture and intervene on the underlying mechanisms. This study paves to way to their identification.
This paper reviews urban heat (UrHT) challenges following the SBAR (situation, background, assessment and recommendation) framework. The results indicate that heatwaves become more frequent, lasting ...and intense, especially after 1990s. Above 1960s level, heatwaves across China doubled in both magnitude and frequency by 2018. Jianghuai and Southern China underwent the largest magnitude and most widespread increases. Under 1.5 °C warming limit, the average heatwave days and duration across China will increase by 10.8 days and 3.9 days. Drought–heatwave co–occurrence is increasingly frequent at 7–11%/decade (from 1961 to 2018) and the co–occurrence leads to more intense heatwaves. UHIs are a common issue for almost all Chinese cities and UHIs have been aggravating annually. Daytime UHIs peak in summer, indicating the synergies with heatwaves. The synergies are prominent in southeastern cities for strong summer daytime UHIs in eastern cities and intense heatwaves in southern regions. UrHTs have not been recognised and there are no dedicated/mandatory plans. Mega–challenges of climate change, rapid urbanisation, carbon– and labour–intensive economic growth and demographic changes can potentially lock China into UrHT challenges. Addressing UrHT challenges is urgent in China not only for environmental, ecosystem, social and health consequences, but also for economic impacts relevant to labour, capital, and goods or services. Efforts are suggested in technical improvement, policy formulation, social participation, economic investment and co-benefit approach recognition. Overall, this paper provides a comprehensive understanding of heat–related challenges in China and can guide the creation of cool cities and communities in practice.
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•Almost all cities in China are under the impacts of urban heat islands.•Heatwaves and urban heat islands can synergise, especially in Southeastern China.•China has not well recognised urban heat challenges and no dedicated plan.•UrHT affects economic productivity by affecting outputs, labour, capital and goods.•UrHT may drive population migrating out the extreme heat areas.
The environmental challenges in cities urge people to explore feasible strategies for resilient, sustainable, healthy and livable built environments, of which designing and building green roof (GR) ...is an important approach. Whilst extensive studies have been proving GR benefits in energy, environmental and ecological aspects, GR implementation (GRI) for achieving such multi-benefits has received limited attention. In order to facilitate GRI, therefore, this paper aims to delineate factors that can affect GRI. This study conducted a systematic review of 186 published papers from 2000 to 2019, for the identification of drivers, motivations and barriers to the GRI. The results indicate that the drivers to GRI include policy pressure, market pressure, and innovation and technology advancement. Besides, GRI can be potentially motivated by multiple factors including energy efficiency, urban heat island mitigation, roof longevity prolongation, air purification, runoff control, water purification, urban infrastructure improvement, sound insulation and noise reduction, biodiversity increase, recreation and aesthetics, property value enhancement and employment improvement. Nevertheless, GRI can be constrained by several barriers such as a lack of government policy, unsound technological level, unsound economic benefit assessment and individual unwillingness. According, this study proposed strategic recommendations in policy, technical, economic and social aspects, with the considerations of various GRI stakeholders (e.g. designer, engineer, constructor and builder, contractor, building operator, owner, end-user, government agent), to strengthen GRI drivers, foster GRI motivations and overcome GRI barriers. Overall, this study is of significance to inform the people with knowledge of factors affecting GRI, which can further promote researchers to explore interrelationships among multiple factors on the one hand and can further promote decision-makers to develop sound policies on the other for GR adoption.
The energy consumption in buildings accounts for a significant proportion of total energy and carbon emissions over the world. To reduce the building energy consumption and achieve sustainable ...development of buildings, nearly zero energy buildings (NZEBs) have attracted widespread attention as a future building energy target. This paper reviews energy-efficient measures (EEMs) and renewable energy technologies (RETs) in NZEBs and discusses the application and suitability of the key technologies, i.e. minimizing the energy demand in NZEBs by EEMs and adopting RETs to meet the remaining energy needs. EEMs contain efficient thermal insulation system, high-performance window system, good airtightness and fresh air heat recovery system. RETs are composed of solar photovoltaic/thermal (PV/T) system, air source heat pump system (ASHP), ground source heat pump system (GSHP), and wind power. In addition, this paper emphasizes further research works, which involve life cycle energy analysis (LCEA), meteorological parameters change, intelligent building operation management (IBOM) system, energy storage system and social policy issues. This paper will provide some references for the further development of NZEBs in different climatic regions in China.
•This paper systematically reviews application of EEMs and RETs in NZEBs in China.•Feasibility and suitability of EEMs and RETs are evaluated from different aspects.•Further research work and development direction of NZEBs are pointed out.
Nonadiabatic holonomic quantum computation (NHQC) has been developed to shorten the construction times of geometric quantum gates. However, previous NHQC gates require the driving Hamiltonian to ...satisfy a set of rather restrictive conditions, reducing the robustness of the resulting geometric gates against control errors. Here we show that nonadiabatic geometric gates can be constructed in an extensible way, called NHQC+, for maintaining both flexibility and robustness against certain types of noises. Consequently, this approach makes it possible to incorporate most of the existing optimal control methods, such as dynamical decoupling, composite pulses, and a shortcut to adiabaticity, into the construction of single-looped geometric gates. Furthermore, this extensible approach of geometric quantum computation can be applied to various physical platforms such as superconducting qubits and nitrogen-vacancy centers. Specifically, we performed numerical simulation to show how the noise robustness in recent experimental implementations Phys. Rev. Lett. 119, 140503 (2017); Nat. Photonics 11, 309 (2017) can be significantly improved by our NHQC+.approach. These results cover a large class of new techniques combing the noise robustness of both geometric phase and optimal control theory.
Since the founding of the People's Republic of China in 1949, significant achievements have been made in cotton production in China. China has maintained its position as the world's largest cotton ...producer for 33 years (1983–2015), with average annual increases of 3.5 and 3.9% in the unit yield and total output of cotton, respectively. Cotton production has played an extremely important role in the development of the national economy and the improvement of living standards. Although the cotton planting area has been reduced in recent years, the total output has remained relatively unchanged due to the continuous increase in the unit yield. China's dominant position in global cotton production is undoubtedly attributed to the progress and development of cotton cultivation technology. Over the past 70 years, China has established a high-yielding and high-efficiency cotton cultivation mode that corresponds to its national conditions, including a large population and a limited land area. Furthermore, cotton cultivation technology is constantly being innovated and developed to keep pace with the times. In this paper, we review the development of cotton production and cultivation in China over the past 70 years, with a particular focus on the innovation and development of cotton cultivation technology with Chinese characteristics. This review is intended to provide guidance for the sustainable development of China's cotton production in the future and to provide a reference for global cotton production.
► Vanadium ion diffusion causes capacity loss in vanadium redox flow battery (VFB). ► Gas side reactions lead to capacity loss in the VFB as well. ► Electrolyte rebalancing is required to restore the ...capacity. ► Dynamic model can help with predicting the capacity loss. ► Control system can be developed to restore the capacity based on the model prediction.
The diffusion of vanadium ions across the membrane along with side reactions can have a significant impact on the capacity of the vanadium redox flow battery (VFB) over long-term charge–discharge cycling. Differential rates of diffusion of the vanadium ions from one half-cell into the other will facilitate self-discharge reactions, leading to an imbalance between the state-of-charge of the two half-cell electrolytes and a subsequent drop in capacity. Meanwhile side reactions as a result of evolution of hydrogen or air oxidation of V
2+ can further affect the capacity of the VFB. In this paper, a dynamic model is developed based on mass balances for each of the four vanadium ions in the VFB electrolytes in conjunction with the Nernst Equation. This model can predict the capacity as a function of time and thus can be used to determine when periodic electrolyte remixing or rebalancing should take place to restore cell capacity. Furthermore, the dynamic model can be potentially incorporated in the control system of the VFB to achieve long term optimal operation. The performance of three different types of membranes is studied on the basis of the above model and the simulation results together with potential operational issues are analysed and discussed.
With the rapid development of urbanization and the improvement of living standards of residents in China, the energy consumption and carbon emissions of the building sector is expected to increase in ...the near future. Nearly or net zero energy buildings have become a hot topic of research to reduce the fossil energy consumption and greenhouse gas emissions in the building sector. As the largest developing country and carbon emitter around the world, China has also made significant efforts on nearly zero energy buildings in recent decades. The central government has approved many demonstration projects on nearly zero energy buildings in different climate zones for more than ten years. This paper summarizes international definitions of zero-energy buildings, analyzes the latest definition and identifies the boundaries of nearly zero energy buildings in China. It provides an overview of the current situation, detailed policies and building codes of nearly zero energy buildings in China. Suggestions were given on the development and promotion of nearly zero energy buildings in China. These findings in this paper will help to guide the government to implement more efficient and effective policies and building codes of nearly zero-energy buildings in order to reduce carbon emissions in the building sector.
•The definitions of ZEB are inconsistent.•Rapid development of ZEB in China is observed.•The current situation of zero energy building in China is presented.•The building codes and policies of ZEB from Chinese central and local governments are summarized.
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