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The IEEE 802.11ah standard, marketed as Wi-Fi Halow, introduces a new channel access mechanism called the Restricted Access Window (RAW), aiming to provide connectivity for the Internet of Things (IoT) applications over broad areas. RAW aspires to alleviate the contention by splitting the channel access into periods and allocating each period to a given group of stations. This paper develops an analytical framework based on Probability and Renewal theories for modeling and evaluating an IEEE 802.11ah-based network implementing the RAW mechanism. We consider a Rayleigh-fading channel with the presence of the capture effect: a realistic scenario for IoT networks deployed in dense urban environments. Considering a single-hop scenario of stations randomly distributed around an Access Point (AP) and the power attenuation of transmitted packets, we model the channel access under capture awareness. As the RAW mechanism presents a time-limited contention for channel access, we develop a counting process that tracks transmissions up to the end of the contention time interval. Henceforth, we evaluate the network performance in terms of throughput. We meticulously validate the derived analytical results through extensive campaigns of discrete-event simulations. Our study evaluates the impact of different parameters on the overall performance, including the contention time, the number of stations, the number of groups, and the capture threshold. We henceforth study the impact of the capture effect on enhancing the network performance under the grouping feature introduced by the RAW mechanism. This work contributes to developing an analytical modeling framework to evaluate the performance of time-limited random access mechanisms accurately and can be an excellent basis for proposing practical scheduling algorithms to configure the RAW mechanism under non-ideal channel conditions. [ABSTRACT FROM AUTHOR]

The Tulcea municipality is frequently exposed to rainfall-generated floods, with its lower downtown area (located in the Danube' former meadow, now protected by dikes) being flooded two to three times per year. In this study, our objective was to understand the generation mechanism of these rainfall-triggered urban floods and to identify tailored mitigation options. Due to the lack of reliable information on the sewage network (diameters, slope, material) and the uncertain sewage outflows during heavy rain events, a rather simplified approach was preferred by the authors of this paper. The data processing was performed using GIS tools, with appropriate accounting of the digital terrain modelling, ortho-photos, administrative boundaries of the Tulcea municipality, delineation of the urban catchments, imagery of the frequently flooded areas, and the urban sewage network. Subsequently, a fast hydrological modelling and a volume-based flooding approach were developed in order to identify and evaluate the flooded urban areas under extreme rainfall events. Upon the completion of the calibration and validation processes, numerical simulations were run that considered the design storms of different return periods. Due to the high slopes of the hills, hence the short concentration time of the pluvial waters, a Sponge City approach does not seem as though it would be easy to implement. A more efficient solution utilising large-capacity buried urban retention tanks in the lower part of the municipality was alternatively identified. Further on, this solution will be supported by a set of green measures. [ABSTRACT FROM AUTHOR]

3D city models integrate heterogeneous urban data from multiple sources in a unified geospatial representation, combining both semantics and geometry. Although in past decades they have predominantly been used for visualization, today they are used in a large range of tasks related to exploration, analysis, and management across multiple domains. The complexity of urban processes and the diversity of urban environments bring challenges to the implementation of 3D city models. To address such challenges, this paper presents the development process of a 3D city model of a single neighborhood in the city of Sofia based on the CityGML 2.0 standard. The model represents the buildings in LOD1, focusing on CityGML features, including building parts, the terrain intersection curve, and the address. Similar building models of 18 cities provided as open datasets are explored and compared to extract good modeling practices. As a result, workflows for the generation of 3D building models in LOD1 are elaborated on and improvements in the feature modeling are proposed. Two building model options are examined: (1) the modeling of a building as a single solid with differentiated rooftops and (2) the modeling of a building with separate building parts. The developed 3D building model contains 471 buildings and 198 addresses in both cases of building parts modeling. In addition, the terrain intersection curve (TIC) is modeled and a method for removing the duplicating TIC features is applied. Consequently, the overall count of vertices of the TIC is lowered from 12,112 to 8042. Finally, the possibilities for visualization of the model in popular platforms such as ArcGIS Pro and Cesium Ion are explored. [ABSTRACT FROM AUTHOR]

Predicting the onset times of precipitation over densely populated cities for the purposes of timely evacuation is a challenge. This paper explored a flooding event over an urban built environment in a South Asian mega city, Chennai, where extant urban planning models rely on predicted rainwater amounts for early warning and impact assessment studies. However, the time duration of flooding events is related to the nature of the urban sprawl in the built environment. Any evacuation measure is invariably tied down to the time duration over which the precipitation event occurs, and therefore to the expected time of a precipitation event to begin. In this context, a crucial parameter useful to municipal authorities is the onset time of precipitation. This study used optimised analytical formulations to predict this time, and the derived analytical expressions for the case study yielded comparable times estimated from a computer-intensive full-scale large eddy model within an accuracy of 2%. It is suggested that municipal authorities (who are non-experts in fluid mechanics) use this early prediction for the purposes of quick alerts to a congested city's most vulnerable citizens within urban sprawls. However, for the procedure to work at its best, it involves a two-stage procedure. The first step involves the use of a parcel model to obtain the expected cloud droplet spectral spreads based on the prevailing dynamical characterisations. The second step involves an optimisation procedure involving cloud spectral properties from the first step to quantify both the auto-conversion rates and the threshold. Thereafter, an onset time calculation based on cloud properties is estimated. These new results are cast in closed form for easy incorporation into meteorological applications over a variety of urban scales. Rain mass amounts were also predicted analytically and used to configure Aeronautical Reconnaissance Coverage Geographic Information System (ARCGIS) to compute low drainage flow rates over the vulnerable parts of Chennai city. It was found that heavy precipitation over the North Chennai region yielded discharge rates to the tune of ~250 m 3 s − 1 during a 24 h period, causing intense flooding in the low-lying areas around the Cooum River basin with a large population density, with estimates sufficiently corroborating observations. [ABSTRACT FROM AUTHOR]

The paper presents the results of a case study that was prepared as a basis for decision-making processes in the context of the impacts of global climate change. The article is focused on a very important part of the urban environment, namely urban forests. When taking planning measures in periurban forests, two realities must always be addressed, i.e., adaptation measures to mitigate the effects of climate change on the forest complex in question and its use to mitigate the effects of climate change in its surroundings must both be considered. It is a well-known fact that forest communities (of any kind) are on the one hand affected by the impacts of climate change, but on the other hand are able to mitigate its effects on their surroundings. The case study was of land near the town of Mladá Boleslav. The aim was to analyse the hydrological regime of the Štěpánka Forest Park, nicknamed "the lungs of Mladá Boleslav". Modelling of the runoff coefficient was made for the whole park area, as well as for the part on the left bank of the Klenice River (forested part). The runoff conditions of the site and their subparameters are addressed in the study by comparing the current state with the modelled state after deforestation of the site, e.g., due to drought. As far as the spatial layout of the forest is concerned, it is absolutely essential to maintain an integrated stand on the site with a lower stem cover (fewer individuals per plot) and a lower regeneration period. These aspects of a growing matrix forest stand will ensure its sustainability, in particular the sustainable water management of the trees in the context of lower water reserves in the rhizosphere and the greater ability of younger individuals to adapt to changes in site conditions (replacement of stress-resistant types by resilient types). [ABSTRACT FROM AUTHOR]

As the majority of people in the world now live in cities, it makes sense to question the state of urban environmental education and how it could be developed going forward. In this article, we suggest a way forward based on the essays written by Finnish university students. The students reflected on their relationship with an environment that is meaningful to them. In the essays selected for this case study (n = 25), the built environment of Helsinki—the capital of Finland—and its characteristics are in focus. In this qualitative research, inductive content analysis was used for processing the essays. Many students described the connections between urban nature and built environments, but the results also show that the built environment is especially significant because of its social and cultural aspects. Students described the importance of social bonding and how meeting different sorts of people supports their acceptance of diverse perspectives. Personal experiences and meanings attached to the city, as well as their lack, were mentioned; that is, without these personal bonds, meaningful relations to urban environments cannot be developed. Architecture, aesthetics, and soundscapes were also mentioned. In addition, it was expressed that feeling safe in the built environment is important. In urban environmental education, it is therefore important to pay attention to the social and cultural aspects, too, and not just to the ecological dimension. It is crucial that children and young people have access to the city in order to construct their personal relationships with the built environment. [ABSTRACT FROM AUTHOR]

The issues related to the urban environment and mental well-being have become increasingly important in recent decades. Although this association has been mainly investigated in developed countries, there is limited knowledge on whether similar results can be acquired in the urban environments of developing countries like Iran. This study intends to present a new dynamic and active approach to determine the environmental quality characteristics that influence the mental well-being of urban residents and to engage people to healthy urban public environments. In this respect, the research is directed by both qualitative and quantitative surveys in the public open spaces of Kermanshah, Iran. Firstly, the data are collected by Grounded Theory (GT) to identify significant environmental quality characteristics related to mental well-being by applying 24 semi-structured interviews. Secondly, the questionnaire survey based on Structural Equation Modeling (SEM) is applied to examine the association between each characteristic of the developed conceptual framework. The results reveal that the environmental quality characteristics of public open spaces, directly and indirectly, relate to users' mental well-being. It should be noted that the public open spaces with unique functional and intrinsic features seem to have different impacts on mental well-being. [ABSTRACT FROM AUTHOR]

Many registration schemes have been proposed to reduce the signaling cost required for user's mobility management in wireless communication networks. Various results on mobility management schemes to minimize the total signaling cost have been reported. The objective of this study was to analyze a registration scheme that could deal with mobility prediction and corresponding flexible tracking area list (TAL) forming. In this scheme, based on mobility prediction and corresponding TAL forms, a new TAL was constructed such that the registration cost could be minimized. In addition, a semi-Markov process model was newly presented for the registration scheme considering mobility prediction and corresponding flexible TAL forming for two different environments: urban and rural. Simulation studies were also performed to validate the accuracy of the semi-Markov process model. Numerical results showed that analytical and simulation results were very close (average relative error of 1.4%). The registration cost decreased as the moving probability (q) to the predicted direction increased. The performance of the proposed scheme was superior to distance-based registration (DBR) or TAL-based scheme especially when q was high. When call-to-mobility ratio was less than or equal to 1 corresponding to current small cell configurations, the proposed scheme outperformed the DBR or TAL-based scheme. [ABSTRACT FROM AUTHOR]

Featured Application: Drones can be a very useful tool to help mosquito control tasks in areas where these insects are an important vector of disease transmission. Storing sterile mosquitoes in drones and releasing them in targeted areas where previous suppression of wild populations has been performed can be a major advance in this methodology. This is part of the sterile insect techniques (SIT) which have been demonstrated to be an environmentally friendly solution for the control of insect pests. However, the use of drones in the areas where these operations are foreseen is limited by the fact that we have a regulation that advances at a slower pace than technology. Of particular interest is the case of the suppression of mosquito populations in urban areas below the transmission threshold, where drones and their operating conditions must meet demanding safety requirements. This article presents the current regulatory situation in Europe that affects drone operations and its applicability to the case of the release of sterile mosquitoes to control the population of these insects in two different scenarios: urban and rural areas. In recent years, several countries have developed the use of sterile insect techniques (SIT) to fight against mosquitoes that transmit diseases. From a technical and economic point of view, the use of drones in the aerial release of sterile mosquitoes leads to important improvements in aerial coverage and savings in operational costs due to the requirement of fewer release sites and field staff. However, these operations are under the European drone regulation, one of the most advanced in the world. The main contribution and novelty of this paper with respect to previous work is the analysis of the SIT application with drones under the European risk-based regulation in two scenarios: urban and rural areas. The specific operations risk assessment (SORA) methodology has been applied to assess the risk of drone operations in these scenarios. The paper presents the operational requirements for aerial release of mosquitoes with drones along with the regulatory considerations that must be applied. Finally, an overview of the conditions in operation that could relax risks and mitigation measures is also discussed. [ABSTRACT FROM AUTHOR]

This paper deals with optimizing the location of ambulance stations in a two-tiered emergency medical system in an urban environment. Several variants of station distribution are calculated by different mathematical programming models and are evaluated by a detailed computer simulation model. A new modification of the modular capacitated location model is proposed. Two ways of demand modelling are applied; namely, the aggregation of the ambient population and the aggregation of permanent residents at the street level. A case study of the city of Prešov, Slovakia is used to assess the models. The performance of the current and proposed sets of locations is evaluated using real historical data on ambulance trips. Computer simulation demonstrates that the modular capacitated location model, with the ambient population demand, significantly reduces the average response time to high-priority patients (by 79 s in the city and 62 s in the district) and increases the percentage of high-priority calls responded to within 8 min (by almost 4% in the city and 5% in the district). Our findings show that a significant improvement in the availability of the service can be achieved when ambulances are not accumulated at a few stations but rather spread over the city territory. [ABSTRACT FROM AUTHOR]

The City of Palma de Mallorca has been historically affected by flood events, with the latest flood of great magnitude occurring in 1962. After decades without large flooding events, since the start of the 21st century, 28 floods have been identified within the city boundaries. As change in the spatial location of these events has been observed, a research to identify where the floods are located nowadays and which causes can be related to such distribution has been undertaken. Six types of floods were identified and the events classified accordingly, with the deficient planned infrastructures, flat urban areas without defined drainage and coastal sectors the three most common types. The results highlight the importance of the urban sprawl and malpractices related to flood risk areas, thus increasing the occurrence of floods of less spatial impact but with greater disturbance on the daily activity of the city inhabitants. Nevertheless, some uncertainties are identified in this research, demonstrating the need of further investigations. [ABSTRACT FROM AUTHOR]

With the various applications of unmanned aerial vehicles (UAVs), the number of UAVs will increase in limited airspace, leading to an increased risk collision. To reduce such potential risk, this work proposes a collision avoidance strategy for UAVs using an enhanced potential field (EPF) approach in cluttered three-dimensional urban environments. Using the EPF formulated in a two-dimensional environment, the avoidance maneuvers for both horizontal and vertical planes are generated by introducing rotation matrices, and these maneuvers are combined by applying a weighting factor. The numerical simulations with various meaningful scenarios are conducted to validate the performance of the proposed approach. To mimic practical situations, UAV dynamics and sensor limitations were considered. The simulation results show that the proposed approach provides an efficient, reliable, and collision-free path without local minima and unreachable goal issues. [ABSTRACT FROM AUTHOR]

This article addresses the global issue of preserving cultural heritage, which is associated, among other things, with the lack of provision for boundaries of protection zones for cultural heritage sites. This paper analyzes the worldwide experience in the field of establishing protection zones for cultural heritage sites, identifies the issues of preserving cultural heritage in Russia, as well as imperfections in the management of lands containing cultural heritage sites. To improve the management of such lands, a method of historical and cultural assessment of territories has been developed, which, on the basis of evaluative factors, makes it possible to characterize the historical and cultural value of a territory. In this article, based on this list of factors, a method for mathematical substantiation of the boundaries of protection zones of cultural heritage sites has been developed; this method includes seven stages. Using mathematical and statistical methods, models were obtained to determine the area of the protection (buffer) zone and the development control zone, the analysis of which revealed differentiation between the factors of historical and cultural assessment that characterize the urban environment, depending on the type of zones. The interpretation of the obtained models and the fields of their use are given. [ABSTRACT FROM AUTHOR]

Modernist planners were given the opportunity to apply the idea of the Modern Movement in the implementation of cities transforming after the World War II blitz, which was not possible before in long-term evolving structures. However, they could not alter everything: some urban and even architectural elements were necessary to be preserved. As a result, the elements of the ancient landscapes of these cities—historical objects and spaces—necessary for the continuity of evidence of history and identity were preserved, often being completely reconstructed. Finally, in some of these cities, both old and new elements contribute to the contemporary urban landscape. The aim of the research is to examine two key categories of urban structure in this perspective: (1) architectural dominants (landmarks) and (2) urban network nodes. For this purpose, (1) the changes in the number and rank of the spaces through which the landmarks expositions were carried out are compared, and (2) the changes in the rank of nodes in the urban structure, both these in the pre-war and in the present structures, as well as changes in their distribution and concentration areas are analyzed. The number of individual elements is compared and the changes in the structure of their arrangement are analyzed with the use of a polygon grid. A medium-scale European city (Bialystok) is used as the case study. Results of our analysis indicate that the post-war reconstruction led to a decrease in the number of elements of the urban grid (streets, nodal points), especially those of low rank. The rank of many others also decreased: 57% of all nodal points within the historical grid of the selected area does not exist in the post-war structure. The number of main rank directions of exposition decreased by 18% and in the subordinate group by 38%. The research is an attempt to construct a new criteria of evaluating changes in the quality of the cityscape, which is described in the article. [ABSTRACT FROM AUTHOR]

The scientific evaluation of landscape fragmentation and connectivity is important for habitat conservation. It is strongly influenced by the spatial resolution of source maps, particularly in urban environments. However, there is limited comprehensive investigation of the spatial grain effect on urban habitat and few in-depth analysis across different urban gradients. In this paper, we scrutinize the spatial grain effects of urban green space (UGS) cover maps (derived from remote sensing imagery and survey data) with respect to evaluating habitat fragmentation and connectivity, comparing among different urban gradient scenarios (downtown, urban periphery, and suburban area) in Hangzhou, a megacity in China. The fragmentation was detected from three indices, including Entropy, Contagion, and Hypsometry. Then morphological spatial pattern analysis (MSPA) was applied for the landscape element identification. The possibility of connectivity (PC) and patch importance (dPC) were proposed for measuring the landscape connectivity based on Cores and Bridges from MSPA results. The results indicate that the farther the location is from downtown, the less sensitive the landscape element proportion to the spatial resolution. Among the three fragmentation indices, the overall hypsometry index has the lowest sensitivity to the spatial resolution, which implies this index’s broader application value. Considering connectivity, high spatial resolution maps are appropriate for analyzing highly heterogeneous urban areas, while medium spatial resolution maps are more applicable to urban periphery and suburban area with larger UGS patches and less fragmentation. This study suggests that the spatial resolution of UGS maps substantially influence habitat fragmentation and connectivity, which is critical for decision making in urban planning and management. [ABSTRACT FROM AUTHOR]

Featured Application: A slit-type soundproof panel can be applied to attenuate low-frequency noise and withstand wind load alongside traffic roads. With the rapid increase in automobiles, the importance of reducing low-frequency noise is being emphasized for a comfortable urban environment. Helmholtz resonators are widely used to attenuate low-frequency noise over a narrow range. In this study, a slit-type soundproof panel is designed to achieve low-frequency noise attenuation in the range of 500 Hz to 1000 Hz with the characteristics of a Helmholtz resonator and the ability to pass air through the slits on the panel surface for reducing wind load. The basic dimension of the soundproof panel is determined using the classical formula and numerical analysis using a commercial program, COMSOL Multiphysics, for transmission loss prediction. From the numerical study, it is identified that the transmission loss performance is improved compared to the basic design according to the shape change and configuration method of the Helmholtz resonator. Although the correlation according to the shape change and configuration method cannot be derived, it is confirmed that it can be used as an effective method for deriving a soundproof panel design that satisfies the basic performance. [ABSTRACT FROM AUTHOR]

The methodological approach of the study proposes an innovative yet adaptive way to define and preserve heritage sites and their elements. In the case study, the proposed methodology guides the design/planning research of heritage sites by linking the perceptual behaviour with the information of the built environment. Visibility is the tool to measure the level of exposure of specific urban elements from a particular perspective. While isovist analyses define visibility in the built environment, fields of view from the periphery of heritage sites are applied to calculate visible or invisible areas by the observer. The purpose of the current study is the evaluation of the identification of the elements to be protected, by modelling both the heritage environment and the heritage elements according to the visibility criteria. For this purpose, I illustrate my approach by using visibility analyses and Space syntax analysis in the case of the Sulukule neighbourhood, the leading renewal project, in Istanbul. This area used to have notably cultural-historical assets-historic land walls, the lifestyle of Roma people--but now the renovation works carried out in the Sulukule case study site have affected the identity of the "visible" and "known" space of the historic quarter. [ABSTRACT FROM AUTHOR]

Due to the limitations of the urban environment, the data transferred between vehicles can only change direction at the intersections. Therefore, the routing decision at an intersection will largely affect the overall routing decision. In this article, we propose an Intersection-Based Routing with Fuzzy Multi-Factor Decision (IRFMF), which utilizes several factors to decide the next road segment. In the scheme, each intersection introduces three factors including the direction, the number of lanes, and the traffic. After the fuzzification and defuzzification of these factors, the candidate segment with the highest evaluation will be selected. The simulation shows a significant improvement of VANETs performance on packet delivery ratio and end-to-end delay. [ABSTRACT FROM AUTHOR]

Urban greenery is widely acknowledged as a key element for creating livable urban environments and improving residents' quality of life. However, only a few current studies on the subject of urban greenery focus on a human visual perspective and take street greenery into consideration. Street greenery is an indispensable component of urban vegetation to which residents have a higher frequency of access. Additionally, few studies focused on the disparity of the green view at a micro-level, such as at a county or community level. This study explored the spatial distribution of street greenery and its influential factors using the green view index (GVI) as the main evaluation indicator. Compared to other traditional indicators of greenery, such as the normalized difference vegetation index (NDVI) and accessibility, GVI is recognized as a human-oriented indicator to evaluate the quantity of greenery viewed by human eyes in daily life. The downtown area of Shanghai was chosen as the case study, as it reflects the common phenomenon of street greenery in many megacities globally. In addition, county/jiedao (the same administrative area as county in China) level was selected as the minimum geographical unit to evaluate the disparity of GVI and its influential factors to fill the knowledge gap. We analyzed 233,000 pieces of street-view images from Baidu Map and other correlated data. The results showed (1) the street greenery of 70% of the downtown area of Shanghai is less than the recommended comforFogre visual environment; (2) street greenery is spatially clustered in Huangpu district, Xuhui district, college town, and the Century Park of Shanghai; (3) street-greenery distribution is positively correlated with housing price and street network density, and negatively correlated with the ratio of society vulnerability; however, it is uncorrelated to population density. According to these findings, local municipalities could improve urban planning and design by introducing a more human-oriented green-space policy that improves social equity. [ABSTRACT FROM AUTHOR]

Naturalization is a new and promising ecological approach to green space development for urban environments, although knowledge is sparse on techniques to implement it. We evaluated naturalization of eight native trees and shrubs, with site preparation (tillage, herbicide) and soil amendment (compost rates) treatment combinations at six sites in the city of Edmonton, Alberta, Canada. Soil texture improved with all compost rates, and acidity, electrical conductivity and total carbon increased, especially with 100% compost. Soil nutrients generally increased with compost then declined within a year. Plant species with highest potential for use in urban green spaces were Picea glauca, Symphoricarpos albus and Rosa acicularis. Herbicide was the most influential site preparation treatment, positively increasing survival and growth of planted woody species, while negatively lowering non-native species cover and increasing noxious weed cover. Soil amendment with compost influenced cover not species richness, with high compost amendment reducing vegetation cover across sites, and increasing individual plant size. This study suggests amendment of soil with compost and appropriate site preparation can positively influence naturalization of these woody species for urban green spaces. [ABSTRACT FROM AUTHOR]

This paper applies a deep learning approach to model the mechanism of path loss based on the path profile in urban propagation environments for 5G cellular communication systems. The proposed method combines the log-distance path loss model for line-of-sight propagation scenarios and a deep-learning-based model for non-line-of-sight cases. Simulation results show that the proposed path loss model outperforms the conventional models when operating in the 3.5 GHz frequency band. The standard deviation of prediction error was reduced by 34% when compared to the conventional models. To explain the internal behavior of the proposed deep-learning-based model, which is a black box in nature, eight relevant features were selected to model the path loss based on a linear regression approach. Simulation results show that the accuracy of the explanatory model reached 72% when it was used to explain the proposed deep learning model. Furthermore, the proposed deep learning model was also evaluated in a non-standalone 5G New Radio network in the urban environment of Taipei City. The real-world measurements show that the standard deviation of prediction error can be reduced by 30–43% when compared to the conventional models. In addition, the transparency of the proposed deep learning model reached 63% in the realistic 5G network. [ABSTRACT FROM AUTHOR]

The mean flow and turbulence statistics of the flow through a simplified urban environment, which is an active research area in order to improve the knowledge of turbulent flow in cities, is investigated. This is useful for civil engineering, pedestrian comfort and for health concerns caused by pollutant spreading. In this work, we provide analysis of the turbulence statistics obtained from well-resolved large-eddy simulations (LES). A detailed analysis of this database reveals the impact of the geometry of the urban array on the flow characteristics and provides for a good description of the turbulent features of the flow within a simplified urban environment. The most prominent features of this complex flow include coherent vortical structures such as the so-called arch vortex, the horseshoe vortex and the roof vortex. These structures of flow have been identified by an analysis of the turbulence statistics. The influence of the geometry of urban environment (and particularly the street width and the building height) on the overall flow behavior has also been studied. Finally, the well-resolved LES results were compared with an available experimental database to discuss differences and similarities between the respective urban configurations. [ABSTRACT FROM AUTHOR]

To reduce CO2 emissions from the building industry, one option is to replace cement in specific applications with alternative binders. The Carbstone technology is based on the reaction of calcium- and magnesium-containing minerals with CO2 to form carbonate binders. Mixes of carbon steel slag and stainless-steel slag, with tailored particle size distributions, were compacted with a vibro-press and subsequently carbonated in an autoclave to produce carbonated steel slag pavers. The carbonated materials sequester 100–150 g CO2/kg slag. Compressive and tensile splitting strength of the resulting pavers were determined, and the ratio was found to be comparable to that of concrete. The environmental performance of the Carbstone pavers, with an average tensile splitting strength of 3.6 MPa, was found to be in compliance with Belgian and Dutch leaching limit values for construction materials. In addition, leaching results for a concrete mix made with aggregates of crushed Carbstone pavers (simulating the so-called "second life" of pavers) demonstrate that the pavers can be recycled as aggregates in cement-bound products after their product lifetime. [ABSTRACT FROM AUTHOR]

Spatial and traffic planning is important in order to achieve a quality, safe, functional, and integrated urban environment. Different tools and expert models were developed that are aimed at a more objective view of the consequences of reconstruction in different spatial and temporal ranges while respecting selection criteria. In this paper we analyze the application of the multi-criteria analysis method when choosing sustainable traffic solutions in the center of a small town, in this case Beliš´ce, Croatia. The goal of this paper is to examine the possibility of improving the methodology for selecting an optimal spatial–traffic solution by combining the quantifiable results of the traffic microsimulation and the method of multi-criteria optimization. Socially sensitive design should include psychological and social evaluation criteria that are included in this paper as qualitative spatial–urban criteria. In the optimization process, different stakeholder groups (experts, students, and citizens) were actively involved in evaluating the importance of selected criteria. The analysis of stakeholders’ survey results showed statistically significant differences in criteria preference among three groups. The AHP (Analytic Hierarchy Process) multi-criteria analysis method was used; a total of five criteria groups (functional, safety, economic, environmental, and spatial–urban) were developed, which contain 21 criteria and 7 sub-criteria; and the weights of criteria groups were varied based on stakeholders’ preferences. The application of the developed methodology enabled the selection of an optimal solution for the improvement of traffic conditions in a small city with the potential to also be applied to other types of traffic–spatial problems and assure sustainable traffic planning. [ABSTRACT FROM AUTHOR]

Accurate simulation of radiative transfer is a very important aspect in climate modeling. For microclimate models in particular, it is not only important to simulate primary but also secondary radiative fluxes in great detail, i.e., emitted longwave and reflected shortwave radiation. As there are always limitations regarding computational effort and memory, these radiative fluxes are commonly implemented using simplified approaches. To overcome these simplifications and, thus, increase modeling accuracy, a new radiation scheme called indexed view sphere was introduced into the microclimate model ENVI-met. This new scheme actually accounts for radiative contributions of objects that are seen by each grid cell. In order to evaluate the advantages of the new scheme, it is compared against the formerly used averaged view factor scheme. The comparison in a complex realistic urban environment demonstrated that the indexed view sphere scheme improved the accuracy and plausibility of modeling radiative fluxes. It, however, yields an increased demand of memory to store the view facets for each cell. The higher accuracy in simulating secondary radiative fluxes should, however, overturn this shortcoming for most studies, as more detailed knowledge of local microclimatic conditions in general and eventually thermal comfort can be gained. [ABSTRACT FROM AUTHOR]

Finding an optimal/quasi-optimal path for Unmanned Aerial Vehicles (UAVs) utilizing full map information yields time performance degradation in large and complex three-dimensional (3D) urban environments populated by various obstacles. A major portion of the computing time is usually wasted on modeling and exploration of spaces that have a very low possibility of providing optimal/sub-optimal paths. However, computing time can be significantly reduced by searching for paths solely in the spaces that have the highest priority of providing an optimal/sub-optimal path. Many Path Planning (PP) techniques have been proposed, but a majority of the existing techniques equally evaluate many spaces of the maps, including unlikely ones, thereby creating time performance issues. Ignoring high-probability spaces and instead exploring too many spaces on maps while searching for a path yields extensive computing-time overhead. This paper presents a new PP method that finds optimal/quasi-optimal and safe (e.g., collision-free) working paths for UAVs in a 3D urban environment encompassing substantial obstacles. By using Constrained Polygonal Space (CPS) and an Extremely Sparse Waypoint Graph (ESWG) while searching for a path, the proposed PP method significantly lowers pathfinding time complexity without degrading the length of the path by much. We suggest an intelligent method exploiting obstacle geometry information to constrain the search space in a 3D polygon form from which a quasi-optimal flyable path can be found quickly. Furthermore, we perform task modeling with an ESWG using as few nodes and edges from the CPS as possible, and we find an abstract path that is subsequently improved. The results achieved from extensive experiments, and comparison with prior methods certify the efficacy of the proposed method and verify the above assertions. [ABSTRACT FROM AUTHOR]

Featured Application: A road environment-type (RET) detection function could improve the road awareness of inexperienced car drivers, especially in urban areas, and by doing so, it could slightly raise the urban traffic safety. A pragmatic implementation could make use of static road object data, e.g., traffic sign (TS) data, that is already collected and available on-board. It could rely on the TS recognition function offered by advanced driver assistance systems (ADAS). Furthermore, apart from its primary function, the RET detection system could provide reciprocal information—with respect to the current RET—for various ADAS and autonomous driving (AD) computations and subsystems. Making use of such reciprocal information could speed up the ADAS/AD computations, and render their results more accurate and more reliable, e.g., via introducing parameter constraints and marking regions-of-interest. For over a decade, urban road environment detection has been a target of intensive research. The topic is relevant for the design and implementation of advanced driver assistance systems. Typically, embedded systems are deployed in these for the operation. The environments can be categorized into road environment-types. Abrupt transitions between these pose a traffic safety risk. Road environment-type transitions along a route manifest themselves also in changes in the distribution of traffic signs and other road objects. Can the placement and the detection of traffic signs be modelled jointly with an easy-to-handle stochastic point process, e.g., an inhomogeneous marked Poisson process? Does this model lend itself for real-time application, e.g., via analysis of a log generated by a traffic sign detection and recognition system? How can the chosen change detector help in mitigating the traffic safety risk? A change detection method frequently used for Poisson processes is the cumulative sum (CUSUM) method. Herein, this method is tailored to the specific stochastic model and tested on realistic logs. The use of several change detectors is also considered. Results indicate that a traffic sign-based road environment-type change detection is feasible, though it is not suitable for an immediate intervention. [ABSTRACT FROM AUTHOR]

The construction industry is one of the most environmentally detrimental industries in the world, impacting directly the use of raw materials, their determination of use involving the whole lifecycle, as well as all their surrounding environment. However, within the building sector, the transition from a linear to a circular economy is still at an early stage. Business models need to be reconsidered to include new and improved methods and innovative services that could lead to a net reduction in the use of resources and minimizing the waste disposed on landfills. In this context, an important role in buildings' circularity is "deconstruction", which is understood as a well-considered selective dismantlement of building components, in prevision of a future reuse, repurposing, or recycling. It represents a sustainable alternative to common demolition, which tends to be an arbitrary and destructive process, and although faster and cheaper, it typically creates a substantial amount of waste. The purpose of this article is to analyze the deconstruction potential of buildings and the strategies to apply in order to keep the impacts on the urban environment low. The article aims to facilitate the implementation of circular economy strategies for buildings by proposing common principles for deconstruction as a sustainable alternative to demolition and defining the key points to be applied during the design and planning process regardless of the type of construction system or material used. [ABSTRACT FROM AUTHOR]

This article presents a system for detecting pedestrian movement patterns in urban environments, by applying computational intelligence methods for image processing and pattern detection. The proposed system is capable of processing multiple images and video sources in real-time. Furthermore, it has a flexible design, as it is based on a pipes and filters architecture that makes it easy to evaluate different computational intelligence techniques to address the subproblems involved in each stage of the process. Two main stages are implemented in the proposed system: the first stage is in charge of extracting relevant features of the processed images, by applying image processing and object tracking, and the second stage is responsible for the patterns detection. The experimental analysis of the proposed system was performed over more than 1450 problem instances, using PETS09-S2L1 videos, and the results were compared with part of the Multiple Object Tracking Challenge benchmark results. Experiments covered the two main stages of the system. Results indicate that the proposed system is competitive yet simpler than other similar software methods. Overall, this article provides the theoretical frame and a proof of concept needed for the implementation of a real-time system that takes as input a group of image sequences, extracts relevant features, and detects a set of predefined patterns. The proposed implementation is a reliable proof of the viability of building pedestrian movement pattern detection systems. [ABSTRACT FROM AUTHOR]

The number of students affected by exam anxiety continues to rise. Therefore, it is becoming progressively relevant to explore innovative remediation strategies that will help mitigate the debilitating effects of exam anxiety. The study aimed to investigate whether green environment exposure, delivered by virtual reality (VR) technology, would serve as an effective intervention to mitigate participants' test anxiety and therefore improve the experience of the exam, measured by positive and negative affect, and increase test scores in a pseudo exam. Twenty high and twenty low exam anxiety students completed a pseudo exam before and after being exposed to either a simulated green environment or urban environment. Only those who had high anxiety and were exposed to the nature VR intervention had significant reductions in negative affect (F(1, 31) = 5.86, p = 0.02, ηp² = 0.15), supporting the idea that exposure to nature, even if simulated, may benefit students' feelings about their academic performance. The findings are discussed in light of future developments in nature and educational research. [ABSTRACT FROM AUTHOR]

Featured Application: The presented numerical approach can be directly applied to the estimation of the compliance boundary of the antenna array base stations and the downlink human EMF exposure assessment in the networks served by such base stations. In the near future, wireless coverage will be provided by the base stations equipped with dynamically-controlled massive phased antenna arrays that direct the transmission towards the user. This contribution describes a computational method to estimate realistic maximum power levels produced by such base stations, in terms of the time-averaged normalized antenna array gain. The Ray-Tracing method is used to simulate the electromagnetic field (EMF) propagation in an urban outdoor macro-cell environment model. The model geometry entities are generated stochastically, which allowed generalization of the results through statistical analysis. Multiple modes of the base station operation are compared: from LTE multi-user codebook beamforming to the more advanced Maximum Ratio and Zero-Forcing precoding schemes foreseen to be implemented in the massive Multiple-Input Multiple-Output (MIMO) communication protocols. The influence of the antenna array size, from 4 up to 100 elements, in a square planar arrangement is studied. For a 64-element array, the 95th percentile of the maximum time-averaged array gain amounts to around 20% of the theoretical maximum, using the Maximum Ratio precoding with 5 simultaneously connected users, assuming a 10 s connection duration per user. Connection between the average array gain and actual EMF levels in the environment is drawn and its implications on the human exposure in the next generation networks are discussed. [ABSTRACT FROM AUTHOR]

The aim of the paper is to describe a multicriteria model predictive control method for autonomous vehicles at non-signalized intersections. The centralized controller aims to describe control action for each autonomous vehicle to guarantee collision free passage. At the same time, performances are defined for the centralized Model Predictive Controller, namely the minimization of traveling time and energy consumption. Since these control goals are often conflicting, a scheduling variable is introduced to create a balance between them. Hence, the centralized controller can be tuned based on the importance of each control goal, which can be useful in urban environment where traffic densities may vary heavily depending on the period of the day. The effectiveness of the proposed centralized multicriteria controller is demonstrated through a complex simulation example in CarSim simulation environment using different tpye of autonomous vehicles. [ABSTRACT FROM AUTHOR]

This work investigated concatenated coding schemes for Global Navigation Satellite System (GNSS) signals in order to increase their error correction capability in urban environments. In particular, a serial concatenated code that combines an outer Reed–Solomon (RS) code with an inner low-density parity-check (LDPC) code was designed, and the performance was investigated over the land mobile satellite (LMS) channel for characterizing multipath and shadow fading in urban environments. The performance of the proposed concatenated coding scheme was compared to that of a B-CNAV1 message, in which two interleaved 64-ary LDPC codes were employed. The simulation results demonstrate that the proposed concatenated code can obtain a similar error correction performance to the two interleaved 64-ary LDPC codes in both the additive white Gaussian noise (AWGN) and LMS channels at a lower complexity level. [ABSTRACT FROM AUTHOR]

In recent years, the self-driving car technologies have been developed with many successful stories in both academia and industry. The challenge for autonomous vehicles is the requirement of operating accurately and robustly in the urban environment. This paper focuses on how to efficiently solve the hierarchical control system of a self-driving car into practice. This technique is composed of decision making, local path planning and control. An ego vehicle is navigated by global path planning with the aid of a High Definition map. Firstly, we propose the decision making for motion planning by applying a two-stage Finite State Machine to manipulate mission planning and control states. Furthermore, we implement a real-time hybrid A* algorithm with an occupancy grid map to find an efficient route for obstacle avoidance. Secondly, the local path planning is conducted to generate a safe and comfortable trajectory in unstructured scenarios. Herein, we solve an optimization problem with nonlinear constraints to optimize the sum of jerks for a smooth drive. In addition, controllers are designed by using the pure pursuit algorithm and the scheduled feedforward PI controller for lateral and longitudinal direction, respectively. The experimental results show that the proposed framework can operate efficiently in the urban scenario. [ABSTRACT FROM AUTHOR]

The usage of indicators as constituent parts of composite indices is an extended practice in many fields of knowledge. Even if rigorous statistical analyses are implemented, many of the methodologies follow simple arithmetic assumptions to aggregate indicators to build an index. One of the consequences of such assumptions can be the concealment of the influence of some of the composite index's components. We developed a fuzzy method that aggregates indicators using non-linear methods and, in this paper, compare it to a well-known example in the field of risk assessment, called Moncho's equation, which combines physical and social components and uses a linear aggregation method to estimate a level of seismic risk. By comparing the spatial pattern of the risk level obtained from these two methodologies, we were able to evaluate to what extent a fuzzy approach allows a more realistic representation of how social vulnerability levels might shape the seismic risk panorama in an urban environment. We found that, in some cases, this approach can lead to risk level values that are up to 80% greater than those obtained using a linear aggregation method for the same areas. [ABSTRACT FROM AUTHOR]

Rooftop photovoltaic (PV) systems in urban environments play an important role in solar electric energy generation. Shading on PV collectors, by self-shading, walls and fences on rooftops, affect negatively the output energy of the PV systems. Increasing the distance between the collector rows, and between the walls and fences near to the collectors, may minimize the shading losses. Practically, this option is usually limited, especially on rooftops. Rooftops may be of different types: horizontal, inclined, and saw-tooth, and may have obscuring structures like walls and fences. The distance between the shading objects and the PV collector rows determine the loss of energy due to shading. The study provides the PV system designer with mathematical expressions for distances from obscuring objects for the deployment of PV systems on rooftops. The optimal inclination and azimuths angles of a PV system on a triangular sloped rooftop are also illustrated. [ABSTRACT FROM AUTHOR]

We investigated the distribution of air temperature (Ta) and the factors affecting it in low-rise areas surrounding an isolated high-rise building during the Japanese winter. The study site was the central part of a regional city in Japan (36°5 0 N, 140°120 E), lying north-east of the Tokyo metropolitan area. The daytime surface temperature (Ts) in the shade is generally considered to be comparable to (Ta); however, according to airborne remote sensing conducted in December 2009 where a multi-spectral scanner was installed on a fixed-wing aircraft, (Ts) for pavements in the shade of a high-rise building was significantly lower than (Ta) of sub-urban areas, indicating an influence of cold storage on (Ts). Then, we conducted mobile observations using instruments (thermocouple, four component radiometer, and so on) installed on a bicycle in January 2016 to investigate the detailed distribution of (Ta) and the factors affecting it. The results showed the (Ta) over the pavements in the shade of the high-rise building was lower than the (Ta) of sunlit areas in the same urban area by −2°C and lower than the (Ta) of sub-urban areas by −1–1.5°C, although the advection effect was large due to strong winds around the building. In conclusion, a locally lower (Ta) compared to the surrounding areas can develop during the day in winter, even in spaces that are open to areas beyond the canopy. [ABSTRACT FROM AUTHOR]

The problem of deterioration of marble or stone monuments on display in the open air was raised in scientific terms around the mid-nineteenth century, correctly sensing the close dependence between the increased speed of surfaces alteration and air pollution. However, only more recently, around the years 1980-1990, emerged a need for quantitative data to assess the degree of degradation and the relative danger in the future projections. Non-destructive techniques can be an important aid in assessing the state of degradation and, above all, its speed, directly on the most important monuments exposed to the urban environment. In this work we discuss some non-destructive techniques able to evaluate the alteration of the surface shape of artefacts exposed to the environment through a non-contact survey of their surface shape. Advantages and disadvantages will be highlighted, as well as the problems still open. [ABSTRACT FROM AUTHOR]

The design and operation of multifunctional infrastructures for public lighting as well as their impact on the urban environment and citizens' life is today of great interest. The cost of energy for public lighting is often an issue for the budget of municipalities. Furthermore, researchers' and designers' attention is increasingly focused on aspects of public lighting not directly valuable through economic factors. Starting from the "quality" of the light environment, looking at citizens' visual comfort, the light has to be considered as an instrument to improve the urban context and objects therein (including buildings). Indeed, urban degradation (lack of infrastructures, maintenance, services, etc.) is linked to the poor quality of everyday issues, such as traffic, pollution, noise, lack of information, long times to access focal points, and the lack of safety. Simultaneously, in many areas, the potential related to the valorization of historical heritage is often underexploited. The installation of efficient lighting systems coupled with the implementation of ICT solutions can provide economic, social, and health benefits, energy efficiency, and visual comfort. On the other hand, as for indoor lighting, these systems can be expensive, not easy to maintain, and not as efficient as expected. The aim of this Special Issue was to investigate the problems and advantages of smart urban lighting systems in more detail. This Special Issue included 6 papers of the 10 submitted papers. [ABSTRACT FROM AUTHOR]

Overheating of buildings and urban areas is a more and more severe issue in view of global warming combined with increasing urbanization. The thermal behavior of urban surfaces in the hot seasons is the result of a complex balance of construction and environmental parameters such as insulation level, thermal mass, shielding, and solar reflective capability on one side, and ambient conditions on the other side. Regulations makers and the construction industry have favored the use of parameters that allow the forecasting of the interaction between different material properties without the need for complex analyses. Among these, the solar reflectance index (SRI) takes into account solar reflectance and thermal emittance to predict the thermal behavior of a surface subjected to solar radiation through a physically rigorous mathematical procedure that considers assigned air and sky temperatures, peak solar irradiance, and wind velocity. The correlation of SRI with the heat released to the urban environment is analyzed in this paper, as well as the sensitivity of its calculation procedure to variation of the input parameters, as possibly induced by the measurement methods used or by the material ageing. [ABSTRACT FROM AUTHOR]

Green roofs offer a series of benefits to buildings and to the urban environment. Their use in dry climates requires optimizing the choice of their components (i.e., vegetation, substrate and drainage layer) for the specific local climatic conditions, in order to minimize irrigations needs while preserving the attributes of the roof. In this study, we calibrated and validated an existing hydrological model--IHMORS--for the simulation of the hydrological performance of green roofs. Simulated results were compared to experimental data obtained in an outdoor test facility on several green roof specimens, representing a variety of green roofs configurations. IHMORS was able to reasonably predict the soil moisture dynamics for all tested specimens. The specimens of 10 cm depth were the best simulated by the model, while some overestimation was observed during the model validation for the 5 and 20 cm depth specimens. The model was then used to estimate the number of days in which irrigation is needed, as well as analyze the water runoff control performance of all specimens. We related the amount of water retained by the substrate and depth, magnitude and intensity of precipitation event, and the initial substrate moisture. For all events, the lowest runoff coefficient was simulated for the 20 cm specimens. Our study showed the full potential of the model for estimating the water needs and the runoff control performances of different variants of green roofs. [ABSTRACT FROM AUTHOR]

Urban public space is extraordinarily adaptable under a pattern of relatively stable changes. However, when facing unprecedented and potentially extreme climatic changes, public spaces may not have the same adaptation capacity. In this context, planned adaptation gains strength against "business as usual". While public spaces are among the most vulnerable areas to climatic hazards, they entail relevant characteristics for adaptation efforts. As such, public space design can lead to effective adaptation undertakings, explicitly influencing urban design practices as we know them. Amongst its different intrinsic roles and benefits, such as being a civic common gathering place of social and economic exchanges, public space may have found an enhanced protagonism under the climate change adaptation perspective. In light of the conducted empirical analysis, which gathered existing examples of public spaces with flood adaptation purposes, specific public space potentialities for the application of flood adaptation measures are here identified and characterized. Overall, this research questions the specific social potentiality of public space adaptation in the processes of vulnerability tackling, namely considering the need of alternatives in current flood management practices. Through literature review and case study analysis, it is here argued that: people and communities can be perceived as more than susceptible targets and rather be professed as active agents in the process of managing urban vulnerability; that climate change literacy, through the design of a public space, may endorse an increased common need for action and the pursuit of suitable solutions; and that local know-how and locally-driven design can be considered as a service with added value for adaptation endeavors. [ABSTRACT FROM AUTHOR]

We present the evolution of multispectral optical properties through urban aerosols that have aged and interacted with biogenic emissions, resulting in stronger short wavelength absorption and the formation of moderately brown secondary organic aerosols. Ground-based aerosol measurements were made in June 2010 within the Sacramento urban area (site T0) and at a 40-km downwind location (site T1) in the forested Sierra Nevada foothills area. Data on black carbon (BC) and non-refractory aerosol mass and composition were collected at both sites. In addition, photoacoustic (PA) instruments with integrating nephelometers were used to measure spectral absorption and scattering coefficients for wavelengths ranging from 355 to 870 nm. The daytime absorption Ångström exponent (AAE) indicated a modest wavelength-dependent enhancement of absorption at both sites throughout the study. From 22 to 28 June 2010, secondary organic aerosol mass increased significantly at both sites, which was due to increased biogenic emissions coupled with intense photochemical activity and air mass recirculation in the area. During this period, the median BC mass-normalized absorption cross-section (MAC) values for 405 nm and 532 nm at T1 increased by ~23% and ~35%, respectively, compared with the relatively less aged urban emissions at the T0 site. In contrast, the average MAC values for the 870 nm wavelength were similar for both sites. These results suggest the formation of moderately brown secondary organic aerosols in biogenically-influenced urban air. [ABSTRACT FROM AUTHOR]

Wind blowing over aquatic and terrestrial surfaces produces aerosols, which include microbial aerosols. We studied the effect of onshore wind speeds on aerosol concentrations as well as total and culturable microbial aerosols (bacterial and viral) at an urban waterfront (New York, NY, USA). We used two distinct methods to characterize microbial aerosol responses to wind speed: A culture-based exposure-plate method measuring viable bacterial deposition near-shore (CFU accumulation rate); and a culture-independent aerosol sampler-based method measuring total bacterial and viral aerosols (cells m-3 air). While ambient coarse (>2 μm) and fine (0.3-2 μm) aerosol particle number concentrations (regulated indicators of air quality) decreased with increasing onshore wind speeds, total and depositing culturable bacterial aerosols and total viral aerosols increased. Taxonomic identification of the 16S rDNA of bacterial aerosol isolates suggested both terrestrial and aquatic sources. Wind appears to increase microbial aerosol number concentrations in the near-shore environment by onshore transport at low wind speeds (<4 m s-1), and increased local production and transport of new microbial aerosols from adjacent water surfaces at higher wind speeds (>4 m s-1). This study demonstrates a wind-modulated microbial connection between water and air in the coastal urban environment, with implications for public health management and urban microbial ecology. [ABSTRACT FROM AUTHOR]

Autonomous driving in public roads requires precise localization within the range of few centimeters. Even the best current precise localization system based on the Global Navigation Satellite System (GNSS) can not always reach this level of precision, especially in an urban environment, where the signal is disturbed by surrounding buildings and artifacts. Laser range finder and stereo vision have been successfully used for obstacle detection, mapping and localization to solve the autonomous driving problem. Unfortunately, Light Detection and Ranging (LIDARs) are very expensive sensors and stereo vision requires powerful dedicated hardware to process the cameras information. In this context, this article presents a low-cost architecture of sensors and data fusion algorithm capable of autonomous driving in narrow two-way roads. Our approach exploits a combination of a short-range visual lane marking detector and a dead reckoning system to build a long and precise perception of the lane markings in the vehicle's backwards. This information is used to localize the vehicle in a map, that also contains the reference trajectory for autonomous driving. Experimental results show the successful application of the proposed system on a real autonomous driving situation. [ABSTRACT FROM AUTHOR]

The so far largely unabated emissions of greenhouse gases (GHGs) are expected to increase global temperatures substantially over this century. We quantify the patterns of increases for 246 globally-representative cities in the Sustainable Healthy Urban Environments (SHUE) database. We used an ensemble of 18 global climate models (GCMs) run under a low (RCP2.6) and high (RCP8.5) emissions scenario to estimate the increase in monthly mean temperatures by 2050 and 2100 based on 30-year averages. Model simulations were from the Coupled Model Inter-comparison Project Phase 5 (CMIP5). Annual mean temperature increases were 0.93 degrees Celsius by 2050 and 1.10 degrees Celsius by 2100 under RCP2.6, and 1.27 and 4.15 degrees Celsius under RCP8.5, but with substantial city-to-city variation. By 2100, under RCP2.6 no city exceeds an increase in Tmean > 2 degrees Celsius (relative to a 2017 baseline), while all do under RCP8.5, some with increases in Tmean close to, or even greater than, 7 degrees Celsius. The increases were greatest in cities of mid to high latitude, in humid temperate and dry climate regions, and with large seasonal variation in temperature. Cities are likely to experience large increases in hottest month mean temperatures under high GHG emissions trajectories, which will often present substantial challenges to adaptation and health protection. [ABSTRACT FROM AUTHOR]

The accurate detection of land subsidence rates in urban areas is important to identify damage-prone areas and provide decision-makers with useful information. Meanwhile, no precise measurements of land subsidence have been undertaken within the coastal Port-Said City in Egypt to evaluate its hazard in relationship to sea-level rise. In order to address this shortcoming, this work introduces and evaluates a methodology that substantially improves small subsidence rate estimations in an urban setting. Eight ALOS/PALSAR-1 scenes were used to estimate the land subsidence rates in Port-Said City, using the Small BAse line Subset (SBAS) DInSAR technique. A stereo pair of ALOS/PRISM was used to generate an accurate DEM to minimize the residual topography effect on the generated interferograms. A total of 347 well distributed ground control points (GCP) were collected in Port-Said City using the leveling instrument to calibrate the generated DEM. Moreover, the eight PALSAR scenes were co-registered using 50 well-distributed GCPs and used to generate 22 interferogram pairs. These PALSAR interferograms were subsequently filtered and used together with the coherence data to calculate the phase unwrapping. The phase-unwrapped interferogram-pairs were then evaluated to discard four interferograms that were affected by phase jumps and phase ramps. Results confirmed that using an accurate DEM (ALOS/PRISM) was essential for accurately detecting small deformations. The vertical displacement rate during the investigated period (2007-2010) was estimated to be -28 mm. The results further indicate that the northern area of Port-Said City has been subjected to higher land subsidence rates compared to the southern area. Such land subsidence rates might induce significant environmental changes with respect to sea-level rise. [ABSTRACT FROM AUTHOR]

Estimation of impervious surface area is important to the study of urban environments and social development, but surface characteristics, as well as the temporal, spectral, and spatial resolutions of remote sensing images, influence the estimation accuracy. To investigate the effects of regional environmental characteristics on the estimation of impervious surface area, we divided China into seven sub-regions based on climate, soil type, feature complexity, and vegetation phenology: arid and semi-arid areas, Huang-Huai-Hai winter wheat production areas, typical temperate regions, the Pearl River Delta, the middle and lower reaches of the Yangtze River, typical tropical and subtropical regions, and the Qinghai Tibet Plateau. Impervious surface area was estimated from Landsat 8 images of five typical cities, including Yinchuan, Shijiazhuang, Shenyang, Ningbo, and Kunming. Using the linear spectral unmixing method, impervious and permeable surface areas were determined at the pixel-scale based on end-member proportions. We calculated the producer's accuracy, user's accuracy, and overall accuracy to assess the estimation accuracy, and compared the accuracies among images acquired from different seasons and locations. In tropical and subtropical regions, vegetation canopies can confound the identification of impervious surfaces and, thus, images acquired in winter, early spring, and autumn are most suitable; estimations in the Pearl River Delta, the middle and lower reaches of the Yangtze River are influenced by soil, vegetation phenology, vegetation canopy, and water, and images acquired in spring, summer, and autumn provide the best results; in typical temperate areas, images acquired from spring to autumn are most effective for estimations; in winter wheat-growing areas, images acquired throughout the year are suitable; and in arid and semi-arid areas, summer and early autumn, during which vegetation is abundant, are the optimal seasons for estimations. Knowledge of optimal time frames, multi-source data, and intelligent algorithms should be integrated to reduce spectral confusion and improve the estimation of impervious surface area from Landsat 8 OLI imagery. [ABSTRACT FROM AUTHOR]

Accurately quantifying the variation of urban green space is the prerequisite for fully understanding its ecosystem services. However, knowledge about the spatiotemporal dynamics of urban green space is still insufficient due to multiple challenges that remain in mapping green spaces within heterogeneous urban environments. This paper uses the city of Hangzhou to demonstrate an analysis methodology that integrates sub-pixel mapping technology and landscape analysis to fully investigate the spatiotemporal pattern and variation of hierarchical urban green space patches. Firstly, multiple endmember spectral mixture analysis was applied to time series Landsat data to derive green space coverage at the sub-pixel level. Landscape metric analysis was then employed to characterize the variation pattern of urban green space patches. Results indicate that Hangzhou has experienced a significant loss of urban greenness, producing amore fragmented and isolated vegetation landscape. Additionally, a remarkable amelioration of urban greenness occurred in the city core from 2002 to 2013, characterized by the significant increase of small-sized green space patches. The green space network has been formed as a consequence of new urban greening strategies in Hangzhou. These strategies have greatly fragmented the built-up areas and enriched the diversity of the urban landscape. Gradient analysis further revealed a distinct pattern of urban green space landscape variation in the process of urbanization. By integrating both sub-pixel mapping technology and landscape analysis, our approach revealed the subtle variation of urban green space patches which are otherwise easy to overlook. Findings from this study will help us to refine our understanding of the evolution of heterogeneous urban environments. [ABSTRACT FROM AUTHOR]

The problem of mixed pixels negatively affects the delineation of accurate surface water in Landsat Imagery. Linear spectral unmixing has been demonstrated to be a powerful technique for extracting surface materials at a sub-pixel scale. Therefore, in this paper, we propose an innovative low albedo fraction (LAF) method based on the idea of unconstrained linear spectral unmixing. The LAF stands on the “High Albedo-Low Albedo-Vegetation” model of spectral unmixing analysis in urban environments, and investigates the urban surface water extraction problem with the low albedo fraction map. Three experiments are carefully designed using Landsat TM/ETM+ images on the three metropolises of Wuhan, Shanghai, and Guangzhou in China, and per-pixel and sub-pixel accuracies are estimated. The results are compared against extraction accuracies from three popular water extraction methods including the normalized difference water index (NDWI), modified normalized difference water index (MNDWI), and automated water extraction index (AWEI). Experimental results show that LAF achieves a better accuracy when extracting urban surface water than both MNDWI and AWEI do, especially in boundary mixed pixels. Moreover, the LAF has the smallest threshold variations among the three methods, and the fraction threshold of 1 is a proper choice for LAF to obtain good extraction results. Therefore, the LAF is a promising approach for extracting urban surface water coverage. [ABSTRACT FROM AUTHOR]