Fields In Urban Environment Research Articles

An optimal sensor placement scheme for wind flow and pressure field monitoring

Sensing of wind pressures on wind-sensitive structures and wind speeds in densely populated cities is crucial to ensure structure safety and monitoring urban wind environment. However, these wind pressure or wind speed sensors are often sparsely distributed due to their high cost, and consequently the collected wind pressure or speed information is limited. Under these circumstances, it is particularly important to place these limited number of sensors in the optimal locations with the capacity of extracting the most information. In this study, an optimal sensor placement scheme based on multi-resolution dynamic mode decomposition (mrDMD), a space post-processing function: signed distance function (SDF) and particle swarm optimization-random forest (PSO-RF) is proposed, called mrDMD-SDF-PSO-RF (mrDSPR). The effectiveness of the proposed scheme is verified using two case studies of reconstruction based on sparse sensors: wind flow field of a city block and wind pressure field of a single building. The result indicates that the proposed scheme significantly improves the efficiency of the sensors. Therefore, based on the proposed optimal sensor placement scheme, the locations of placing sensors can be well-designed for various wind engineering problems, which builds a solid foundation of super-resolution reconstruction of wind pressure on buildings and wind flow field in urban environment.

Tactical urbanism in the context of urban practices development in Ukraine

The article presents the study of tactical urbanism phenomenon as a way of integrating a person into the socio-cultural environment of the city. The works and publications of both domestic and western researchers are considered. The research sources are outlined: from the classics of sociology to contemporaries, informational and analytical Internet resources which highlight the content of the tactical urbanism ideas. The author has revealed that the research focus of the predecessors is mainly focused on rethinking the problem of urban area spatial development. Taking into account this, the process of research definitive field theorizing is highlighted (starts from M.Castells).The content of «tactical urbanism» concept in the public discourse presented. It should be understood as targeted actions of the city authorities and the public in the field of urban environment in order to fill its traditional content. The process of urbanization movement institutionalization in the context of domestic development is presented. The domestic formal / informal local initiatives are analyzed. The basic forms and practices of tactical urbanism are demostrated, the circle of actors involved in the process of their realization is outlined. The main results of the sociological research showing the level of citizens responsibility and involvement in the process of improvement / arrangement of the city’s territory are highlighted. The features of the tactical urbanism phenomenon in the context of the domestic society development in modern conditions are generalized. It is established that the citizens involvement in the practice of tactical urbanization is fairly called a new form of civil participation. However, the results of the conducted sociological research have shown that despite the development of tactical urbanism ideas in the context of domestic urban practices implementation, the population readiness in urban changes and the level of their responsibility for these changes remains low.

ANALYSIS OF ELECTROMAGNETIC WAVES SPATIO-TEMPORAL VARIABILITY IN THE CONTEXT OF EXPOSURE TO MOBILE TELEPHONY BASE STATION

With the increasing number of mobile phone users, new services and mobile applications, the proliferation of radio antennas has raised concerns about human exposure to electromagnetic waves. This is now a challenging topic to many stakeholders such as local authorities, mobile phone operators, citizen and consumer groups. The study of the spatial and temporal variability of the actual downlink exposure is a very important requirement to find an accurate exposure assessment. In this paper, a concept of exposure areas linked to specific variations of the electric field is introduced. Then a measurement campaign of the temporal variability of the electric field in urban environment is presented, considering different technologies and mobile operators in the previously defined exposure areas. This study allowed to determine updated daytime and nighttime exposure profiles. A second result yielded the averaging duration needed to reach a stable evaluation of the electric field exposure levels, inside each exposure area and according to each technology.

Measurements of global current density and electric field in urban environment

Results of continuous and simultaneous measurements of global current density (flowing between ionosphere and the earth) and electric field intensity (in the vicinity of the earth surface) are presented. The results were obtained in a measuring system placed 20 m above ground level. Using the continuity equation, the conductive and displacement components of current density (as well as conductivity of the atmosphere) were determined. It was found that the displacement part of the total current is much smaller in comparison to the conduction one. Analysis of measurement showed a high coincidence of the electric field derivative with the time course of the global current. Temporal courses of conductivity indicate the presence of space charge and suggests the continuity equation is supplemented with a space charge component. The calculated average value of the short-period (10 min long) current density was found to be on the level of 2-3 pA m−2 (average conductivity of the order of 15-20 fS m−1). At the same time period the average value of field intensity was on the level of 150-300 V m−1.

Social Contribution of Remote Sensing Technology in the Field of Urban Environment, Civil Engineering and Construction

Social Contribution of Remote Sensing Technology in the Field of Urban Environment, Civil Engineering and Construction

Medio Ambiente Urbano: una mirada desde la historia de las ideas científicas y las profesiones de la ciudad

This article will approach the issue of urban Buenos Aires between 1850 and 1915 from a perspective that can enrich the existing body of knowledge on environmental history, especially deepening scientific conceptions that guided the practice in the field of urban environment.

Statistical study of the influence of building architectural properties on scattered fields in urban environment

Statistical studies on the reflection coefficient of concrete–glass building facades are conducted using a fast and an accurate method based on the Green’s functions. The variation of different architectural parameters, such as concrete permitting and distribution, size and type of windows, are studied. The influence of selected parameters on the total reflection coefficient of the building is quantified for different incidence and observation angles as well as in different diffraction zones.

GRID-Based Prediction of Electromagnetic Fields in Urban Environment

In this paper, a grid-based 3D ray tracing procedure is presented for the prediction of electromagnetic field in urban environment in the presence of multipaths, reflections and diffractions. In the procedure, electromagnetic field strength is obtained by all the contributions originated, evaluated by exploiting the ray tracing method in grid environment. The obtained results have shown the good performance of the grid environment for the prediction leading to reduction of one-order of magnitude of the computing time.

Recent advances in modeling the propagation noise in high-rise cities

In the past few decades, we have witnessed a rapid growth in mechanized transport and transportation systems. We live in a transport-dominated society which has led to a marked improvement in dispersal of land use and to the increased opportunity for the separate development of residential, commercial, and industrial areas. In dense and high-rise cities, various modes of land transportation are the primary source of noise. The problem of transportation noise is not confined by political or social frontiers. It affects the rich who may live in a quiet residential area but who must make full use of transport to maintain their affluent existence, as well as the less fortunate who must live close to a highway, a major road, or an elevated railway line. A systematic development of the capability for accurate predictions of the propagation of land transportation noise in dense high-rise cities is highly desirable. This paper summarizes the current models for predicting sound fields in urban environments and gives an overview of the recent advances of various numerical models to predict the sound field in urban environments. [Work supported by the Research Grants Council of the Hong Kong SAR Government and the Hong Kong Polytechnic University.]

Statistical distributions of fields in urban environment based on Monte Carlo simulations of Maxwell equations

We studied wave propagation in an urban environment based on Monte Carlo simulations of Maxwell's equations. The multilevel steepest descent fast multipole method (ML/SD/FMM) is used in the computations. The building profile is about 2 km in length and the frequency is 900 MHz. Numerical results are statistically analyzed to study the spatial variations, including fast fading, shadow fading, and range dependence. The results are compared with the Rayleigh, Rician, and lognormal distributions.

Diversity techniques for mobile radio reception

After discussing the nature of the electromagnetic field in urban environments, and the use of diversity techniques in fading media, the paper presents a survey of these techniques as applied to mobile radio, with emphasis on systems designed for analogue communication. It includes a unified approach to systems based on the double-heterodyne phase-stripper principle. The discussion is not restricted to present-day receivers only, but includes considerations which may apply in future designs.

Diversity techniques for mobile radio reception

After discussing the nature of the electromagnetic field in urban environments, and the use of diversity techniques in fading media, the paper presents a survey of these techniques as applied to mobile radio, with emphasis on systems designed for analogue communication. It includes a unified approach to systems based on the double-heterodyne phase-stripper principle. The discussion is not restricted to present-day receivers only, but includes considerations which may apply in future designs.