Propagation In Urban Areas Research Articles

Effect of Land Cover on Tsunami Overland Flow Propagation: A Case Study of Painan, West Sumatra, Indonesia

Tsunami overland flow may cause severe destruction to the affected coastal area. Several tsunamis had hit Indonesia. Studies have shown that there is a high probability of a massive earthquake in the Mentawai fault, Sumatra, Indonesia. A massive earthquake with a magnitude of over 8 Mw might occur in the next 50 years. The nearshore tsunami propagation and inundation in Painan City, West Sumatra, Indonesia, is assessed using HEC-RAS. Various land cover types are simulated to investigate their effects on the tsunami overland flow. The model showed satisfactory results. The model can show the known behaviors of tsunami propagation in urban areas and in rivers. It was found that there is a significant effect of land cover types on the inundation at the coast. Inundation depth increases with roughness along the coast. On the other hand, high roughness decreases the inundated area. Furthermore, the land cover has a significant effect on the velocity. The velocity is much lower in higher Manning’s value. Simulation with a high surface roughness shows a significant reduction in both inundation area and velocity. The high roughness causes a blockage effect for tsunami propagation. Thus, the Tsunami cannot penetrate further inland. The information can be used for land use control suggestions. These provide significant information for future mitigation plans, e.g., placement of evacuation buildings and evacuation routes.

Noise Propagation in Urban Area from Chimneys of Thermal Power Plants

Large energy facilities are noise sources of the adjacent to them urban buildings. In case of noise propagation from pipes, the assessment of the noise mode of the urban building area is a complex scientific-practical problem of building physics. The solution of the problem is carried out consistently in two stages. At first, the noise distribution in channels from ventilator to the mouth of the pipe is determined. Proposed calculation model takes into account sizes and shape of channel and pipe, noise insulation properties of the walls and the mirrored-diffuse nature of the sound reflection from the fences. For metal ducts, 95% of reflected sound energy is mirrored, and other 5% of it is diffusely. The distribution of emitted by pipe sound energy within urban building is found at the next stage. A new method is suggested for solution of this problem. It is based on received analytical dependence of the sound energy directivity factor from the mouth of pipe and integration of its diffraction. To implement the method a computer program is developed. The program makes it possible to assess the propagation of noise inside ducts and in an open space from the mouth of the pipe to various sites of buildings. To realize the method, an example of calculation of noise emitted by the chimney of a steam boiler of a thermal power plant in Moscow is given. The example shows the potential of suggested calculation model and its computer realization for the noise mode assessment of the adjacent to energy facilities urban buildings.

Analysis of Interference Between LTE System and TETRA System in The 800 MHz Band

Wireless communication is used in many sectors to support the need of communication, the example of wireless communication is applied in mission critical network. Wireless communication system that used in mission critical are Terrestrial Trunked Radio (TETRA) and Long Term Evolution (LTE). TETRA systems supports voice services while LTE supports voice and data services. Co-exsitence between LTE and TETRA in same frequency band is one of the optimilazition quality for mission critical network. For this final project analyses interference in co-exsitence between LTE and TETRA in frequency band 800 MHz. There are four scenarios using extended-hata model propagation in urban area. There are several parameters that reviewed, desired Received Signal Strength (dRSS), interfering Received Signal Strength (iRSS), Carrier to Interference ratio (C/I) and probability of interference. In all scenarios occur Co-Channel Interference (CCI) between LTE and TETRA in frequency band 800 MHz so the performance not optimal. The performance increased when add guard band variation. The variation that applied are 0,5 MHz, 0,75 MHz, 1 MHz. Based on the result of the simulation that have been done, proposed the used of guard band variation for elevate the performance.

Congestion Detection and Propagation in Urban Areas Using Histogram Models

Rapid growth of urbanization makes the roadways exacerbate many problems like traffic congestion, road accidents, and passenger discomfort. Many actions have been taken globally to solve or reduce this impact but still the congestion problem seems to be persistent globally. In this paper, we propose a new histogram-based model for congestion detection. We subsequently extended our model with the base platform concept and use Intelligent Transportation System (ITS) technologies to provide a novel rerouting strategy. The proposed model enables the microscopic visualization of the traffic patterns for every individual lane and predicts the congestion in priori and takes actions proactively. The rerouting strategy used in our approach provides a novel solution to the congestion problem by taking precaution measures prior to the critical point of congestion occurrence. The proposed algorithm is compared with various existing algorithms and the simulation results show that the proposed model addresses the congestion problem effectively and provides better solution compared to existing algorithms.

Characterization of Outdoor to Indoor Propagation in Urban Area by Using A Combination of COST231 Walfisch-Ikegami and COST231 Multiwall Models in 1800 Mhz and 2100 Mhz

Increasing numbers of the mobile communication users in urban city; especially indoor users cause the radio coverage prediction of outdoor to indoor becoming important. Obstacles are the main problems for outdoor to indoor propagation that weaken signal level and worsen information detection. This paper proposes a combination of COST231 Walfisch-Ikegami and COST231 Multiwall to predict the received signal. By comparing the predicted and the measured signal level in the Antara building, Medan city for both 1800 MHz and 2100 MHz channels, the proposed model outperforms the compared method in predicting signal level. The proposed model is able to suppress the prediction deviation 11.035 dB lower than the compared method for Sector A and 5.98 dB lower at Sector B.

Stormwater Inundation Analysis in Small and Medium Cities for the Climate Change Using EPA-SWMM and HDM-2D

Kim, S.E.; Lee, S.; Kim, D., and Song, C.G., 2018. Stormwater Inundation Analysis in Small and Mediun Cities for the Climate Change Using EPA-SWMM and HDM-2D. In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp. 991–995. Coconut Creek (Florida), ISSN 0749-0208.The increase of rainfall intensity and flash-flood due to climate change are expected to exacerbate flood inundation in urban area. Especially, small and medium cities lacking drainage facilities are more vulnerable to flood inundation than large cities. This study introduces a simplified urban stormwater inundation simulation modelling for the two small and medium-sized cities located in South Korea using the U.S. Environmental Protection Agency (EPA) Storm Water Management Model (SWMM) and a HydroDynamic Model-2D(HDM-2D). EPA-SWMM model which are widely used to the runoff analysis of urban areas containing drainage pipe network, was used to calculate runoff flow and surcharged overflow of the existing urban drainage network. Then, a 2-D inundation model, HDM-2D was coupled with 1-D EPA-SWMM model to simulate the flood propagation in urban areas. The 1-D/2-D coupled model was calibrated with the real rainfall events and applied to analyze the effect of climate change on urban stormwater inundation for the 30-year frequency of design rainfall calculated by RCP 4.5 of the IPCC RCPs. In a simplified inundation analysis based on 1-D/2-D coupled simulation, the small-scale urban flooding in the small and medium cities was rapidly propagated within two hours after the occurrence of a surcharge overflow. The flooding wave propagation was highly related to the flow interaction with topographical obstacles as road, and bottom elevation or slope.

Discrete Simulation of Sound Propagation in the City Based on Cellular Automaton

This paper deals with the problem of sound propagation in urban areas. It begins by investigating the propagation of sound in order to determine and extract the physical parameters that direct this propagation. The formalism of cellular automata (CA) is presented, as well as its use for the specification of physical phenomena, with discrete events, such as sound propagation. The use of cellular automata in a smart city context, to model the propagation of sound is presented. The proposed model takes into account buildings and other city obstacles. A CUDA Implementation of this model is described. This implementation is used to simulate sound propagation on shapefile cards. The proposed model makes it possible to determine the sound power in a given location and the geographic area covered by the sound wave.

Optimum Path Loss Model Calibration for Prediction DTTV Propagation in Urban Area of Southern Thailand

Optimum Path Loss Model Calibration for Prediction DTTV Propagation in Urban Area of Southern Thailand

Optimized Walficsh-Bertoni Model for Path Loss Prediction DTTV Propagation in Urban Area of Southern Thailand

Optimized Walficsh-Bertoni Model for Path Loss Prediction DTTV Propagation in Urban Area of Southern Thailand

Optimization of Path Loss Model for Prediction DTTV Propagation in Urban Area of Southern Thailand

Optimization of Path Loss Model for Prediction DTTV Propagation in Urban Area of Southern Thailand

The initial development of a hybrid method for modeling outdoor sound propagation in urban areas

Accurately modeling urban outdoor sound propagation is a difficult problem. Using a frequency-domain or time-domain method is too expensive, and using an engineering, geometrical, or statistical method is too restrictive. For example, the ISO 9613-2, NMPB-Roads, and CNOSSOS-EU engineering methods only model diffraction for straight barriers. The Nord2000 and Harmonoise engineering methods can also model diffraction from wedge-shaped screens, but these modeling capabilities are still insufficient to model many potential noise mitigation solutions such as a gamma or T-shaped barrier. To extend the applicability of engineering methods, a detailed model like the boundary element method could characterize a complicated noise mitigation device versus a simple reference device. This presentation discusses the initial development of this hybrid method.

Hata's Path Loss Model Calibration for Prediction DTTV Propagation in Urban Area of Southern Thailand

This article presents Hata's path loss model calibration in order to predict a design of the Digital Terrestrial Television (DTTV) Propagation in an urban area of the south of Thailand through measuring power signal of the network operators’ broadcasting in 4 channels within Haadyai urban area, Songkla Province. The chosen location is a density area, a distance of 2.5-6.5 km. from the broadcasting station. The calibration was conducted through a statistical method of Root Mean Square Error (RMSE) from received power signal and compared with a path loss model from the prediction, followed by looking for relative errors to indicate the efficiency of the calibration model. The RMSE analytical result of CH 26 with the frequency of 514 MHz; CH 42 with the frequency of 642 MHz; CH 46 with the frequency of 674 MHz; CH 54 with the frequency of 738 MHz shows that Hata's path loss model calibration is closer to the measured data than the original and the other model whereas the relative errors are closer to zero than the predicted path loss model. This makes the Hata's path loss model calibration become more accurate in the prediction and subsequently more suitable for use in planning the network design.

Accounting for the effect of diffuse reflections and fittings within street canyons, on the sound propagation predicted by ray tracing codes

Diffusion on building facades and fittings within a street can significantly affect sound propagation in urban areas. These phenomena are however not reproduced by the widespread outdoor sound propagation models that are based on ray codes algorithms, because their modeling would induce increased computational costs. In this paper, a set of 32 175 simulations is achieved with a sound particle tracing code to quantify the errors made when neglecting acoustic diffusion within street canyons, according to the street geometry (width, height, distance between the point source and the receiver), the acoustical properties of the street (diffusion and absorption coefficient of the facades, absorption coefficient of the ground), and the acoustical properties of the fittings (mean free path and average absorption coefficient), in the case of a receiver height of 1.5m. The diffuse reflections can lead to reduction of 2dB to an increase of 4dB of sound pressure levels in the absence of fittings, and can lead to an increase of 10dB of sound pressure levels in the presence of fittings, for the most unfavorable configurations. The influence of the acoustical parameters and the influence of the street geometry on sound attenuation are closely linked to each other. Moreover, acoustic diffusion results in an overall sound level increase if one considers a linear point source distribution. Finally, regressions are proposed that estimate the impact of diffusive reflections and street fittings on sound propagation as a function of the input parameters. These regressions can now be advantageously used to refine sound levels estimations within street canyons, when using classical outdoor sound propagation models, in the range of the parameters tested.

English

The massive increase of wireless communications in the world calls for responsible actions by governments in order to prevent possible health hazards. In addition to cellular towers overcrowding in urban areas, it is also important to consider other radio frequency radiations from different sources. The electric field intensity is one of the fundamental parameters to assess the exposure of human beings to Non-Ionizing Radiation (NIR). In this study, all main non-ionizing radiation sources in the urban area of Natal, Brazil (a city of about 860.000 inhabitants) were located and characterized with respect to frequency band, telecommunications service and integrated electric field strength. Measurements of far electric field intensity with frequency ranging from 30 MHz to 3 GHz were made in a survey of 140 outdoor points spread across all the 167.26 km2 area of the city. The results obtained have made it possible to draw a map of the regions of the city according to different electric field and exposure ratio (ER) intensities. In 71.4% of the sampled outdoor points, the highest exposure ratio measured were originated from TV broadcasting services, 22.1% from Transmissions Cellular Towers and 6.4% from Frequency Modulated Broadcasting. Key words: Non-ionizing radiation, electric field intensity, TV broadcasting, radio frequency radiation, measurement of radio frequency radiation, propagation in Urban Areas, International Commission on Non-Ionizing Radiation Protection (ICNIRP).

Low frequency acoustic resonances in urban courtyards

Urban courtyards can be regarded as open cavities in the urban area, in which resonances can be excited by waves generated in the neighboring streets. The aim of the present work is to experimentally and numerically investigate low frequency resonance phenomena in these configurations. Experiments are carried out in a scale model and a numerical study is performed with a coupled modal-finite elements method. The method enables the three-dimensional modeling of the acoustic field and thus to take into account the interactions between the courtyard and the street canyon that occur above the roof level, a particular characteristic of wave propagation in urban areas. The attention is focused on two aspects, the amplification of the sound level inside the courtyard and the acoustic attenuation in the street due to resonances. Experimental and numerical results are in good agreement and show a strong resonant behavior of these configurations.

Location Estimation Using Geometry of Overhearing Under Shadow Fading Conditions

Drastic propagation conditions in wireless environments, specifically the presence of non-line-of-sight (non-LOS) propagation in urban areas, pose a major challenge to the acquisition of location information. Count-of-Beacon (COB) is a new radiolocation technique where the absence of a LOS path does not degrade the precision of the estimated position. In this technique, the distance between a mobile terminal and a base station can be derived by means of the geometry of overhearing. The geometry of overhearing models the correlation between the position and the proportion of overheard power-controlled beacon packets. However, the deviation of the attenuation that signals experience, mainly due to shadow fading, has not been considered in this model. This paper reformulates the geometry of overhearing by focusing on the effects of shadow fading. Simulation results are used to verify the validity of the new derived model at different levels of shadowing. The closed-form expression of the Cramer-Rao lower bound (CRLB) is also derived to benchmark the accuracy of the COB technique. In addition, the major source of error affecting the precision of the COB technique is identified and its statistical description is provided.

Division of critical flow at three-branch open-channel intersection

An experimental study of the characteristics of dividing critical flows in a 90° open-channel junction formed by three horizontal equal-width branches is presented, conducted for various inflow discharges and downstream boundary conditions. Outflow discharges and flow depths were also measured. Four main flow patterns are identified considering the location and length of the hydraulic jumps that develop across the main and lateral channels. A relationship between the discharge division ratio and the tailwater Froude number is found, reproducing well the experimental data. Practical applications of this relationship include the design of open channel and pipe networks and one-dimensional numerical modelling of flood propagation in urban areas. The study shows also that a two-dimensional depth-averaged numerical model hardly gives better predictions of the discharge ratios because of the presence of three-dimensional features at the junction.

Modelling flash flood propagation in urban areas using a two-dimensional numerical model

This paper reports on the numerical modelling of flash flood propagation in urban areas after an excessive rainfall event or dam/dyke break wave. A two-dimensional (2-D) depth-averaged shallow-water model is used, with a refined grid of quadrilaterals and triangles for representing the urban area topography. The 2-D shallow-water equations are solved using the explicit second-order scheme that is adapted from MUSCL approach. Four applications are described to demonstrate the potential benefits and limits of 2-D modelling: (i) laboratory experimental dam-break wave in the presence of an isolated building; (ii) flash flood over a physical model of the urbanized Toce river valley in Italy; (iii) flash flood in October 1988 at the city of Nimes (France) and (iv) dam-break flood in October 1982 at the town of Sumacarcel (Spain). Computed flow depths and velocities compare well with recorded data, although for the experimental study on dam-break wave some discrepancies are observed around buildings, where the flow is strongly 3-D in character. The numerical simulations show that the flow depths and flood wave celerity are significantly affected by the presence of buildings in comparison with the original floodplain. Further, this study confirms the importance of topography and roughness coefficient for flood propagation simulation.

Use of the transmission line matrix method for the sound propagation modeling in urban area

This paper deals with the sound propagation modeling in urban area. This problematic requires to take into account many phenomena that can have a substantial impact as well in semienclosed spaces as on long-range outdoor sound propagation, such as reflections and absorption on the frontages and on the ground, atmospheric attenuation, sound velocity variations related with wind and temperature vertical gradients, atmospheric turbulences. The numerical method used is the TLM (transmission line modeling), which has been originated in electromagnetism and adapted for acoustics applications. It consists in a physical rendering of the waves propagation based on the Huygens' principle. It is established on a spatiotemporal discretization of the domain using an iterative temporal process for sound pressure propagation, instead of the resolution of mathematical equations. The TLM model has then been developed in two and three dimensions allowing to combine all the phenomena affecting the sound propagation in urban area. Numerical simulations are given for canyon streets.

Predictions of sound pressure levels in streets using a diffusion model: numerical validations and experimental comparisons

Predictions of sound propagation in urban areas have attracted a considerable over the years. If the sound energy is assimilated to particles with a constant energy, their movement can be described by a transport equation. In canyon streets, this transport equation can be reduced to a diffusion equation whose expression is more simple. In this presentation, sound absorption at the boundaries (buildings facades and ground), as well as atmospheric sound attenuation are introduced. The problem is then solved numerically using a finite elements method for the configuration of a canyon street. A systematic validation of the obtained model is carried out in terms of sound pressure level by comparison to numerical simulations taken from the literature. Comparisons with experimental data are then conducted. Finally, applications in more complex configurations are presented.