Open Urban Environments Research Articles

Thermal conductivity of an external wall with simulated smart Aerogel insulation system

Modern technologies are more than ever adopting intelligent designs that respond to environmental variants to produce more desirable outcomes. In the building and housing industries, intelligent designs aim to conserve energy through temperature controls and energy storage and distribution systems. In this context, an intelligent Aerogel insulation system is modelled and studied for the exterior building walls. Aerogel with a thermal conductivity of about 0.012 W/m-K has a superior insulating property, and an intelligent design built around it would introduce additional energy storage and delivery enhancements to the system. In this study, a test room and a control room in an open urban environment were built, and the intended intelligence, first considered by choosing Aerogel that has the potential to be engineered with smart properties according to researchers in composite material science, and second was considered by automation which was applied manually to the test room. The calculated thermal conductivity of an external wall with intelligent Aerogel insulation is -(1.83 ± 0.06) × 10−1 W/m. The negative sign is an attribute of a system function rather than of a material. The external wall with intelligent Aerogel insulation, in comparison to an identical non-insulated wall, exhibited 2.7 times better energy conservation.

Physical and CFD model used in the analysis of particles dispersion

Air pollution, representing one of the major environmental crises affecting us all, is responsible for half a million deaths each year in Europe. This research shows a numerical model based on Computational Fluid Dynamics (CFD) and a methodology for its validation allowing to know the evolution of particles in open urban environments. In this case, the model represents an area of Gijón (Asturias), specifically chosen as it serves to highlight a location at which the daily limit values of PM10 set by the regulations are most frequently exceeded. A numerical model has been developed at a scale of 1:10,000 to simulate the dispersion of pollutants, including particulate emissions. A physical model at the same scale was built using 3D printing. This model was tested in a wind tunnel and analysed in the four main wind directions. To carry out the tests, a particle generation system was designed and manufactured, and the necessary infrastructure was built to take measurements using an optical particle meter. Results show that the numerical model meets the expected objectives and is capable of predicting the behaviour of particle dispersion in the air. The numerical model produces results in the same order of magnitude as the physical model, although there is a tendency to underestimate the maximum values with respect to the measured ones.

TRENDS OF DEVELOPMENT OF PUBLIC SPACE FORMS

The article summarizes the main forms of public space and their types and development trends. Features of open, covered, atrium forms of public space and public space with a complex structure are described.
 The conditions of the active functioning of a comfortable public space are considered. Examples of progressive projects of the organization of public space, which are implemented in world practice and which illustrate the proposed classification of public spaces by form, are given. Modern possibilities of organizing public space, which can be included inside the building and located outside relative to the buildings, are based on the main groups of forms: open public space (area with design in an open urban environment), covered public space (area with design in an open urban environment with canopy structure), atrium public space (communication and recreation atrium part of a public building) and public space of a complex structure (combination of open, covered and atrium parts: vertically at different levels or by blocking horizontally). The most complicated form of a complex with public space is a multi-level combination of a transport hub, a shopping center and a recreation area on the upper levels.

Background noise but not urbanization level impacted song frequencies in an urban songbird in the Pearl River Delta, Southern China

Rapid urbanization has profoundly transformed habitats and increased noise pollution in urban environments. Elevated noise levels may mask acoustic signals of urban-dwelling organisms such as birds. Singing at higher frequencies is one of typical responses to avoid this masking effect. However, high-frequency signals experience larger attenuation when transmitting in open urban environments. Here, we tested how elevated noise and urbanization affect frequency characteristics and song complexity in the Oriental Magpie-robin (Copsychus saularis), a common urban songbird in tropical Asia. Song recording was conducted in seven cities in the Pearl River Delta, southern China, a highly developed region with rapid pace of urbanization. Our results showed that Magpie-robins sang with higher minimum and maximum frequencies in noisier areas. Neither noise level nor urbanization level impacted other song features, including song length, syllable rate, number of syllables, number of unique syllable types, and syllable transitions in songs. Furthermore, noise level did not affect the choice of song post sites. Our results imply elevated noise levels could induce spectral but not temporal and structural modifications. Taken together, our study adds to a growing number of publications illustrating how phenotypes of birdsongs have been changed in anthropogenic soundscapes.

Sistema de Reconocimiento de Señalamientos en Entornos Abiertos para la Orientación de Personas con Discapacidad Visual

En este trabajo se presenta el desarrollo de un prototipo que permite identificar señalamientos específicos a través de técnicas de visión artificial. Utiliza una etapa de segmentación de imagen basada en el algoritmo de superpíxeles SLIC, seguida de una etapa de reconocimiento y clasificación de señalamientos basada en redes neuronales convolucionales que se ha implementado en un ordenador de placa reducida (SBC). El prototipo informa al usuario de la identificación de estos señalamientos a través de un mensaje de audio enviado a un auricular, cuenta con un módulo GPS que obtiene la ubicación donde se reconoció el señalamiento y se almacena para ofrecer al usuario notificaciones sobre señalamientos cercanos. Las pruebas fueron realizadas con señalamientos a escala 1:2 en entornos abiertos, con luz de día. El prototipo pretende ser un apoyo para que personas con discapacidad visual puedan desplazarse en entornos abiertos urbanos. Tiempos de procesamiento y desempeño del prototipo son reportados. Si bien la implementación en el ordenador de placa reducida seleccionado hace inviable su uso por los tiempos de operación, se demuestra la funcionalidad del sistema.

Can we use local climate zones for predicting malaria prevalence across sub-Saharan African cities?

Malaria burden is increasing in sub-Saharan cities because of rapid and uncontrolled urbanization. Yet very few studies have studied the interactions between urban environments and malaria. Additionally, no standardized urban land-use/land-cover has been defined for urban malaria studies. Here, we demonstrate the potential of local climate zones (LCZs) for modeling malaria prevalence rate (PfPR) and studying malaria prevalence in urban settings across nine sub-Saharan African cities. Using a random forest classification algorithm over a set of 365 malaria surveys we: (i) identify a suitable set of covariates derived from open-source earth observations; and (ii) depict the best buffer size at which to aggregate them for modeling PfPR.Our results demonstrate that geographical models can learn from LCZ over a set of cities and be transferred over a city of choice that has few or no malaria surveys. In particular, we find that urban areas systematically have lower PfPR (5%–30%) than rural areas (15%–40%). The PfPR urban-to-rural gradient is dependent on the climatic environment in which the city is located. Further, LCZs show that more open urban environments located close to wetlands have higher PfPR. Informal settlements—represented by the LCZ 7 (lightweight lowrise)—have higher malaria prevalence than other densely built-up residential areas with a mean prevalence of 11.11%. Overall, we suggest the applicability of LCZs for more exploratory modeling in urban malaria studies.

Vegetation and microclimate in open urban areas. Cuiabá, Mato Grosso - Brazil

The influence of vegetation on the reduction of heat in open urban environments by providing a milder and more pleasant microclimate is highlighted in modern science. The objective of this study was to evaluate the trend of microclimatic variables and thermal comfort, in the Federal University of Mato Grosso - UFMT campus, in open spaces (forest fragment, cerrado and paved) with and without afforestation. Three collection points were selected in open spaces (wooded and without afforestation) at the UFMT campus in Cuiabá. To record the data, we used the Alloet Thermohigrometer mini-markers, model TA-318 with 0.1%. The collections took place in May of 2018, period that begins the local winter. The microclimatic variables such as air temperature, relative humidity (%), wind speed, ultraviolet index and chance of rain were analyzed daily from 09:00 to 17:00 for 15 days. The results highlight the importance of the shade provided by the tree vegetation in the forest fragment, which revealed a significant difference for the thermal comfort in relation to the other sample points and without afforestation. The microclimatic parameters present variations of the temperature and relative humidity of the air at the points allocated, with emphasis on the thermal comfort sensation for the wooded area. The research also suggests new scientific investments in studies on urban micro-climates as a way to stimulate and raise awareness of the importance of vegetation in thermal comfort, which can directly reflect the health and well-being of people in general.

Mobility Acceptance Factors of an Automated Shuttle Bus Last-Mile Service

The main interest of this paper is to analyze the mobility acceptance factors of an automated shuttle bus last-mile service. There is limited research on the passengers’ perception of security and safety of automated mobility, whereas prior research is mostly based on surveys interested in attitudes towards self-driving vehicles, without being linked to the experience. We, on the other hand, are interested in passengers’ feeling of security and safety, after taking a ride with an automated shuttle in an open urban environment. For studying this, we conducted an automated shuttle bus last-mile pilot during a four-month period in the city of Tallinn in late 2019. The method is a case study focusing on one city with several tools for data collection applied (surveys, interviews, document analysis). The pilot, open and free for everybody, attracted approximately 4000 passengers, out of which 4% responded to the online feedback survey. For studying the operational capacity, we had a panel interview with operators of the shuttle service, in addition to analyzing daily operational log files. The results indicate that passengers’ perceived feeling of security and safety onboard was remarkably high, after taking a ride (and lower without a ride, in a different control group). The bus was operated only if operational capacity was secured, thus having significant downtime in service due to environment, technology and traffic-related factors.

Caractérisation de la végétation des friches situées au sein d’un réseau d’infrastructures de transport : le cas de la vallée de l’Huveaune – Marseille / Characterisation of the vegetation of urban wastelands situated within transport infrastructure sites : the case of the Huveaune valley – Marseille

Often considered as abandoned sites of no value, colonised by vegetation that is depreciated, disordered and poorly maintained, urban wastelands are today in France the focus of major territorial issues, in particular with regard to the preservation of the biodiversity and the development of Green and Blue Infrastructure. Featuring among the last ‘wild’ natural spaces, but also the last areas in the city that are still available for urban development, they are universally coveted. From the ecological point of view, the biological diversity of these areas in the Mediterranean region remains largely unknown. A study was therefore undertaken on 24 urban wastelands situated within the transport infrastructure sites of the lower Huveaune valley between Marseille and Aubagne, in south-east France, in order to characterise the vegetation of these areas with regard to the taxonomic, morphological and biological aspects. The analysis of the floristic data resulting from vegetation transects shows that these infrastucture wastelands, rich and diversified, are dominated by five herbaceous species of the Poaceae family, in which a few shrub and tree species cohabit. The dominant plant species are characteristic of ruderal, open urban environments, and are accompanied by roadside and field edge plant species that are evidence of the long history of changes of land occupation and use that the valley has been witness to and of recent disturbances to which it has been subjected. The micro-topography related to the transport infrastructure system does not appear to have any influence on the structure and composition of the floristic composition of wasteland sites, except on the frequency of certain biological and morphological traits. The maintenance carried out on the transport infrastructure embankment wastelands may be a factor that explains the differences observed. These visually perceptible differences may also contribute from the aesthetic and affective points of view to the variation of the degree of appreciation by the general public of the plant diversity between the sloping and non-sloping wasteland sites.

Assessing the effects of landscape characteristics on the thermal environment of open spaces in residential areas of Beijing, China

For high-density urban environments, improving local landscapes can effectively ameliorate the thermal environment. With the aim of assessing the effect of landscape characteristics on thermal performance in open spaces of residential areas, we took field measurements using mobile traverses in 18 residential areas of Beijing, China during the daytime in summer (June–August 2014) and winter (December 2014–February 2015). The net differences (d) of air (dATs) and radiation temperature (dRTs) between residential and nearby corresponding urban open environments, regarded as indicators of the thermoregulation of the 18 residential areas, were calculated. The effects and relative contributions of different landscape characteristics to the indicators were further investigated. Within residential areas, there were overall lower ATs and RTs compared with the control sites in open urban environments. The maximum and minimum dAT and dRT ranged from 0.53 to 6.14 °C and 3.16 to 8.65 °C in summer, and from −0.50 to 1.25 °C and −0.84 to 4.01 °C in winter, respectively. The net dATs and dRTs were significantly different among the 18 residential areas. An increasing percentage of vegetation cover and arbor-shrub planting density and decreasing percentage of pavement area, percentage of building cover and distance to downtown had varying degrees of favorable effects on dAT and dRT. In contrast, average building height had a slight seasonally opposite regulating impact. Compared with dAT, the net dRT is more sensitive to changes in landscape characteristics. The relative contribution of different landscape parameters to explaining the differences in the two types of temperature differed and varied by season. The percentages of pavement area and vegetation cover played the most important roles in summer and winter. If appropriately combined, local landscape characteristics could effectively ameliorate local thermal environments.

The impact of urban planning strategies on heat stress in a climate-change perspective

Spatial and temporal characteristics of outdoor heat stress for a redevelopment area in Gothenburg, Sweden, in a climate change perspective, using mean radiant temperature (Tmrt) as a proxy for heat stress is presented. The impact of climate change on Tmrt was evaluated using statistically downscaled data from a regional climate model. The simulated average Tmrt for the future scenarios was not higher than for today’s climate, because the increased longwave radiation fluxes caused by higher temperatures were offset by reduced shortwave radiation fluxes caused by increased cloudiness. The spatial pattern of Tmrt in the study area during warm and clear weather is primarily governed by the shadow patterns of buildings and vegetation. The highest average-daytime Tmrt was found at open locations, but because open areas also have the highest frequency of sunlit occasions, this does not necessarily imply that open areas are most prone to heat-stress. When considering only occasions during clear and warm weather situations, the highest Tmrt were usually found close to sun-exposed, south-facing walls. Under these criteria, denser urban environments have lower heat stress than more open urban environments. The warmest areas were also found to be the warmest areas in the future as well.Tree-shadows are an effective measure to reduce daytime Tmrt. Trees was found to have the largest impact on Tmrt in open areas where vegetation is sparse, especially when the distance to the nearest “cool” place is used as a measure of heat-stress.

Perception of Length to Width Relations of City Squares

In this paper, we focus on how people perceive the aspect ratio of city squares. Earlier research has focused on distance perception but not so much on the perceived aspect ratio of the surrounding space. Furthermore, those studies have focused on “open” spaces rather than urban areas enclosed by walls, houses and filled with people, cars, etc. In two experiments, we therefore measured, using a direct and an indirect method, the perceived aspect ratio of five city squares in the historic city center of Delft, the Netherlands. We also evaluated whether the perceived aspect ratio of city squares was affected by the position of the observer on the square. In the first experiment, participants were asked to set the aspect ratio of a small rectangle such that it matched the perceived aspect ratio of the city square. In the second experiment, participants were asked to estimate the length and width of the city square separately. In the first experiment, we found that the perceived aspect ratio was in general lower than the physical aspect ratio. However, in the second experiment, we found that the calculated ratios were close to veridical except for the most elongated city square. We conclude therefore that the outcome depends on how the measurements are performed. Furthermore, although indirect measurements are nearly veridical, the perceived aspect ratio is an underestimation of the physical aspect ratio when measured in a direct way. Moreover, the perceived aspect ratio also depends on the location of the observer. These results may be beneficial to the design of large open urban environments, and in particular to rectangular city squares.

Effects of habitat and urbanization on the active space of brown-headed cowbird song

The ability of a receiver to detect a signal is a product of the signal characteristics at the sender, habitat-specific degradation of the signal, and properties of the receiver's sensory system. Active space describes the maximum distance at which a receiver with a given sensory system can detect a signal in a given habitat. Here the effect of habitat structure and urbanization on brown-headed cowbird (Molothrus ater) perched song active space was explored. The active space of the cowbird song was affected by both habitat type and level of urbanization. High frequency (4 to 6 kHz) portions of song resulted in the maximum active space. Surprisingly, the active space was the largest in open urban environments. The hard surfaces found in open urban areas (e.g., sidewalks, buildings) may provide a sound channel that enhances song propagation. When the introductory phrase and final phrase were analyzed separately, the active space of the introductory phrase was found to decrease in open urban environments but the active space of the final phrase increased in open urban environments. This suggests that different portions of the vocalization may be differentially influenced by habitat and level of urbanization.

Optimised COST-231 Hata Models for WiMAX Path Loss Prediction in Suburban and Open Urban Environments

In Malaysia, the incumbent WiMAX operator utilises the bands of 2360-2390MHz to provide broadband services. Like all Radio Frequency (RF), WiMAX is susceptible to path loss. In this paper, field strength data collected in Cyberjaya, Malaysia is used to calculate the path loss suffered by the WiMAX signals. The measured path loss is compared with the theoretical path loss values estimated by the COST-231 Hata model, the Stanford University Interim (SUI) model and the Egli model. The best model to estimate the path loss based on the path loss exponents was determined to be the COST-231 Hata model. From this observation, an optimised model based on COST-231 Hata parameters is developed to predict path loss for suburban and open urban environments in the 2360-2390MHz band. The optimised model is validated using standard deviation error analysis, and the results indicate that the new optimised model predicts path loss in both suburban and open urban environments with very low standard deviation errors of less than 4.3dB and 1.9dB respectively. These values show that the model optimisation was done successfully and that the new optimised models will be able to determine the path loss suffered by the WiMAX signals more accurately. The optimised model may be used by telecommunication providers to improve their service.

Solar radiation calculation methodology for building exterior surfaces

The present article shows a new methodology of calculation of the direct, diffuse and reflected incident solar radiation, in all type of surfaces, either in open urban environments or inside buildings. This methodology is applicable in problems related to solar access (space heating in buildings, shadowing of open spaces), solar gains (space cooling in buildings), and daylighting. Solar radiation is the most important contribution to the surface and volumetric energy balance during the daytime. Particularly, solar radiation is the main contributor to heat gains in buildings, especially in residential buildings, where internal gains are very low. Utilization of daylight in buildings may result in significant savings in electricity consumption for lighting while creating a higher quality indoor environment. Additional energy savings may also be realized during cooling season, when reduction of internal heat gains due to electric lighting results in a corresponding reduction of cooling energy consumption. The analysis of the existing calculation methods and proposed in the scientific bibliography for the calculation of the solar radiation in problems of solar access in winter, solar gains in summer, and daylighting, takes us to the necessity of outlining a new and complete methodology. This new methodology is applicable to all these problems with a great accuracy and calculation speed.

1.9‐Ghz‐band radio propagation characteristics in an open urban environment and tree loss prediction using a loss layer model

AbstractFor design of optimum microcells on a university campus, it is necessary to determine the propagation characteristics within a propagation environment represented by a relatively large open space scattered with large buildings and many trees. In this paper, for the radiated waves from seven PHS base sites at 1.9 GHz experimentally installed on the campus of Hokkaido University from 1993 to 1994, a median received signal level measurement method is proposed that can be applied in unpaved garden areas (with glass and pebbles) as well as in areas with woods, vegetation, and hilly terrain, and its effectiveness is discussed. Next, for quantitative evaluations of the increase of the propagation loss due to trees in the propagation paths on the campus, a propagation model is proposed that consists of the loss layer model and the geometrical optics two‐ray model. In the loss layer model, the loss due to trees is replaced with a loss per unit length of the propagation path. The estimated median received signal level and the measured value are compared to determine the effectiveness of the model. The increase of the propagation loss on the campus due to trees can be estimated if the loss per unit length of the tree layer by the present loss layer model is chosen to be about 0.1 dB/m for the base site antenna installed on the rooftop of the building and 0.07 to 0.09 dB/m for the antenna installed on the roof of the public phone box. © 2001 Scripta Technica, Electron Comm Jpn Pt 1, 84(8): 49–61, 2001