The urban environment has changed vastly over past decades, which also has had an impact on our sleep and dietary patterns and possibly health outcomes. Some studies have shown that sleep duration ...and sleep quality has declined over past decades, especially in children. In parallel, our lifestyle and dietary patterns have also changed including more shift work, more meals outside the home or family setting and more irregular eating patterns, including breakfast skipping and late-night eating. This new area of research in nutritional sciences studying the impact of the timing of eating on health outcomes is called chrono-nutrition, and combines elements from nutritional research with chrono-biology. The objectives of this paper were to discuss secular trends in sleep patterns and related dietary patterns, introduce basic concepts and mechanisms of chrono-nutrition and discuss the evidence for the importance of sleep and chrono-nutrition in relation to health outcomes. Overall, chrono-nutrition could mediate the effects between sleep, diet and urbanisation, and more research is needed to elucidate the importance of chrono-nutrition for metabolic health and its impact on public health.
Integrity is one criteria to evaluate GNSS performance, which was first introduced in the aviation field. It is a measure of trust which can be placed in the correctness of the information supplied ...by the total system. In recent years, many GNSS-based applications emerge in the urban environment including liability critical ones, so the concept of integrity attracts more and more attention from urban GNSS users. However, the algorithms developed for the aerospace domain cannot be introduced directly to the GNSS land applications. This is because a high data redundancy exists in the aviation domain and the hypothesis that only one failure occurs at a time is made, which is not the case for the urban users. The main objective of this paper is to provide an overview of the past and current literature discussing the GNSS integrity for urban transport applications so as to point out possible challenges faced by GNSS receivers in such scenario. Key differences between integrity monitoring scheme in aviation domain and urban transport field are addressed. And this paper also points out several open research issues in this field.
In an urban environment, dual vertical axis wind turbines (VAWTs) are expected to demonstrate more advantage than horizontal axis wind turbine. For VAWT, solidity is one of the most important ...characteristics, while it has not been well studied. In this study, to investigate the effect of rotor solidity and other characteristics on the power output of counter-rotating dual VAWTs at different rotor centre spacings in a low turbulence intensity condition, twelve wind tunnel experiments for dual VAWTs and six wind tunnel experiments for an isolated VAWT were conducted. The results show that the effect of the dual VAWTs configuration on the VAWT power output is small compared with isolated VAWT under low wind speeds in an urban environment, but the effect exhibits a slight improvement with an increase in rotor solidity. As rotor solidity decreases, the sensitivity of the effect on rotor centre spacing increases. The effect of skewed flow on the power output of dual VAWTs are also well discussed. Furthermore, dual-VAWT systems are studied under real urban environment of a number of major cities such as Guangzhou, London, and Copenhagen. Potentials in different heights are compared with different configurations based on the city planning of those major cities.
•An experimental test on various dual-rotor system was conducted in a wind tunnel.•The relationship between solidity and the dual rotor system is analyzed.•The performance of the dual rotor system under skewed flow is discussed.•The potential of dual rotor system on building are studied in various major cities.
Urban subsurface monitoring requires high temporal‐spatial resolution, low maintenance cost, and minimal intrusion to nearby life. Distributed acoustic sensing (DAS), in contrast to conventional ...station‐based sensing technology, has the potential to provide a passive seismic solution to urban monitoring requirements. Based on data recorded by the Stanford Fiber Optic Seismic Observatory, we demonstrate that near‐surface velocity changes induced by the excavation of a basement construction can be monitored using existing fiber optic infrastructure in a noisy urban environment. To achieve satisfactory results, careful signal processing comprising of noise removal and source signature normalization are applied to raw DAS recordings. Repeated blast signals from quarry sites provide free, unidirectional, and near‐impulsive sources for periodic urban seismic monitoring, which are essential for increasing the temporal resolution of passive seismic methods. Our study suggests that DAS will likely play an important role in urban subsurface monitoring.
Plain Language Summary
Seismic monitoring can provide crucial information about near‐surface changes due to natural or manmade activities. However, the high cost and the “after‐effect” nature of conventional station‐based monitoring methods limit their application in urban environments where near real‐time and meter‐scale resolution are required. Distributed acoustic sensing has the potential to achieve all requirements utilizing existing communication infrastructure. Using Stanford Fiber Optic Seismic Observatory, we demonstrate that its recordings of quarry blasts 13.3 km away carry important subsurface velocity information within the footprint of the array. These short bursts of quarry blast signals provide us free, unidirectional, and repetitive sources that sample the urban subsurface at an interval frequent enough for monitoring. We observe large velocity decrease from the recordings close to the excavation site. Our study suggests that telecommunications fiber repurposed for distributed acoustic sensing will potentially play an important role in many urban subsurface monitoring applications.
Key Points
Using the Stanford DAS array, we demonstrate the reliability of urban DAS recordings when deployed in existing infrastructures
Short DAS recordings of far‐field quarry blasts show sensitivity to the changes in near‐surface velocity within the boundaries of the array
DAS can play an important role in real‐time, high‐resolution, and long‐term urban monitoring applications
The dynamic development of modern cities requires new solutions to urban planning and management by local regional authorities. The paper focuses on ecological indicators based on Earth Remote ...Sensing Data (ERSD) of the snow cover with the purpose to evaluate the city and to plan ecological environment protection strategy. The paper deals with the method of using space images to assess the snow cover pollution of Chelyabinsk, a large Russian industrial city. The assessment of the snow cover of Chelyabinsk was carried out by comparing the heavy metals concentrations with the Landsat 8 data. The spectral indices were calculated for fourteen sites evenly distributed over the urban area of four types: courtyards, car parks, industrial zones and roads. We found a statistically significant difference between the Swirl/Green index and the site type and a correlation with the concentrations of dissolved and suspended forms of heavy metals in snow cover. Snow cover indices can be used as ecological indicators of urban environment.
There is increasing interest in the influence of place on health, and the need to distinguish between environmental and individual level factors. For environmental-level factors, current evidence ...tends to show associations through cross-sectional and uncontrolled longitudinal analyses rather than through more robust study designs that can provide stronger causal evidence. We restricted this systematic review to randomised (or cluster) randomised controlled trials and controlled before-and-after studies of changes to the built environment. Date of search was December 2016. We identified 14 studies. No evidence was found of an effect on mental health from ‘urban regeneration’ and ‘improving green infrastructure’ studies. Beneficial effects on quality-of-life outcomes from ‘improving green infrastructure’ were found in two studies. One ‘improving green infrastructure’ study reported an improvement in social isolation. Risk-of-bias assessment indicated robust data from only four studies. Overall, evidence for the impact of built environment interventions on mental health and quality-of-life is weak. Future research requires more robust study designs and interdisciplinary research involving public health, planning and urban design experts.
•Comprehensive systematic review of built environment interventions & mental health.•Weak evidence for the impact of built environment interventions on mental health.•Guidance on reducing risk of bias for these studies is provided.•Strategies, using innovative methods, are needed to improve evidence in this field.
•Inequality in urban greenspace exposure is assessed for 303 cities in China.•Dynamic inequality is characterized using multi-source geospatial data.•Severe inequality in greenspace exposure is ...pervasive in Chinese cities.•Dry cold climate and urban densification contribute to high inequality.
Given the important role of green environments playing in healthy cities, the inequality in urban greenspace exposure has aroused growing attentions. However, few comparative studies are available to quantify this phenomenon for cities with different population sizes across a country, especially for those in the developing world. Besides, commonly used inequality measures are always hindered by the conceptual simplification without accounting for human mobility in greenspace exposure assessments. To fill this knowledge gap, we leverage multi-source geospatial big data and a modified assessment framework to evaluate the inequality in urban greenspace exposure for 303 cities in China. Our findings reveal that the majority of Chinese cities are facing high inequality in greenspace exposure, with 207 cities having a Gini index larger than 0.6. Driven by the spatiotemporal variability of human distribution, the magnitude of inequality varies over different times of the day. We also find that exposure inequality is correlated with low greenspace provision with a statistical significance (p-value < 0.05). The inadequate provision may result from various factors, such as dry cold climate and urbanization patterns. Our study provides evidence and insights for central and local governments in China to implement more effective and sustainable greening programs adjusted to different local circumstances and incorporate the public participatory engagement to achieve a real balance between greenspace supply and demand for developing healthy cities.
Non-exhaust emissions (NEE) of particulate matter (PM) from brake, tyre, road pavement and railway wear, as well as resuspension of already deposited road dust, account for up to 90% by mass of total ...traffic-related PM emitted. This review aims at analysing the current knowledge on road traffic NEE regarding sources, particle generation processes, chemical and physical characterization, and mitigation strategies. The literature on this matter often presents highly variable and hardly comparable results due to the heterogeneity of NEE sources and the absence of standardized sampling and measurement protocols. As evidence, emission factors (EFs) were found to range from 1 mg km−1 veh−1 to 18.5 mg km−1 veh−1 for brake wear, and from 0.3 mg km−1 veh−1 to 7.4 mg km−1 veh−1 for tyre wear. Resuspended dust, which varies in even wider ranges (from 5.4 mg km−1 veh−1 to 330 mg km−1 veh−1 for cars), is considered the prevailing NEE source. The lack of standardized monitoring approaches resulted in the impossibility of setting international regulations to limit NEE. Therefore, up until now the abatement of NEE has only been achieved by mitigation and prevention strategies. However, the effectiveness of these measures still needs to be improved and further investigated. As an example, mitigation strategies, such as street washing or sweeping, proved effective in reducing PM levels, but only in the short term. The replacement of internal combustion engines vehicles with electric ones was instead proposed as a prevention strategy, but there are still concerns regarding the increase of NEE deriving from the extra weight of the batteries. The data reported in this review highlighted the need for future studies to broaden their research area, and to focus not only on the standardization of methods and the introduction of regulations, but also on improving already existing technologies and mitigating strategies.
Display omitted
•NEE are relevant PM sources in urban areas, exceeding EE contribution.•Emission standards and clean air policies must focus on NEE.•Standardized NEE sampling and measurement methods are needed to set regulations.•Among NEE sources, resuspended dust exceeds brake, tyre, and road wear.•EVs have no tailpipe emissions, but still produce a significant amount of NEE.
Gas-phase oxygenated organic molecules (OOMs) can contribute substantially to the growth of newly formed particles. However, the characteristics of OOMs and their contributions to particle growth ...rate are not well understood in urban areas, which have complex anthropogenic emissions and atmospheric conditions. We performed long-term measurement of gas-phase OOMs in urban Beijing during 2018–2019 using nitrate-based chemical ionization mass spectrometry. OOM concentrations showed clear seasonal variations, with the highest in the summer and the lowest in the winter. Correspondingly, calculated particle growth rates due to OOM condensation were highest in summer, followed by spring, autumn, and winter. One prominent feature of OOMs in this urban environment was a high fraction (∼75%) of nitrogen-containing OOMs. These nitrogen-containing OOMs contributed only 50–60% of the total growth rate led by OOM condensation, owing to their slightly higher volatility than non-nitrate OOMs. By comparing the calculated condensation growth rates and the observed particle growth rates, we showed that sulfuric acid and its clusters are the main contributors to the growth of sub-3 nm particles, with OOMs significantly promoting the growth of 3–25 nm particles. In wintertime Beijing, however, there are missing contributors to the growth of particles above 3 nm, which remain to be further investigated.
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