The archaeological analysis of Historical mobility is an increasingly studied topic thanks to new geographic information technologies. This paper proposes a modelling exercise of the spatial ...behaviour of a Second Iron Age community in the Middle Tagus Valley: the hillfort of Villasviejas del Tamuja (Botija, Cáceres). Based on our knowledge of the configuration of the site and the surrounding settlements, we propose a heuristic use of a series of GIS tools to understand how the spatial relationship between both elements was structured. More specifically, we compare the results obtained with different calculation methods that combine two essential variables to address this issue: mobility and visibility relations. On the one hand, we evaluate the results with the application of an already developed methodology: the MADO analysis. On the other hand, we present a complementary procedure for the calculation of Least Cost Paths (LCP), considering the visibility as a key element in the mobility. The methodology uses the same data, in a paradigmatic case study for comparing results. The differences obtained through the use of different tools are thus evaluated in order to weigh up the additional or complementary knowledge that they can provide us with to investigate archaeological research questions such as the defensive architecture of the hillfort or the distribution of other nearby settlements.
•Advance spatial understanding without direct connections, vital when central locations are known but routes are not.•LCPV as an alternative for mobility analysis compared with MADO.•LCPV's flexibility includes adding visibility criterion in mobility analysis.
The main objective of this work was to evaluate human exposure to electromagnetic fields in a city of about one hundred thousand inhabitants, both inside and outside dwellings, using exposure ...quotients. To this end, a personal exposure meter was used, collecting data in different frequency bands, including radio and television broadcasting, mobile telephony, cordless telephones, and wireless communication networks. The indoor measurements were made with the exposure meter in a static position. Those outdoor were made by walking around the building with the exposure meter held by the operator. The median electric field was 0.200 V/m outdoors and 0.102 V/m indoors. The median of the ICNIRP exposure quotients for multiple-frequency sources was 25 10−6 outside and 16 10−6 inside. The proximity of the operator's body caused the readings of the electric field in the FM band to be overestimated by a factor of 1.35, and in the mobile telephony bands by factors from 0.76 to 1.02. The standard deviation of the measurements repeated inside a dwelling over five days was of the order of the exposure meter's standard uncertainty of calibration, but the spatial dispersion at the scale of a dwelling and of the city was much greater. The two main contributors to the exposure were FM radio followed by the “downlink” mobile telephony bands. Inside the dwellings, the DECT and WIFI bands contributed less. Exposure quotients are dimensionless parameters that characterize exposure, and reflect the relative weight of each service to that exposure.
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•Residential areas were measured indoors and outdoors with a personal exposimeter.•Different protocols were used for indoor and outdoor measurements.•Electric field was systematically detected in the FM and downlink mobile phone bands.•Median exposure quotient was 2.5 10−6 outdoors and 1.6 10−6 indoors.•Exposure quotient: FM radio > downlink > DECT and WIFI.
A type of contamination that has been little studied in cars comes from the extremely low frequency (ELF) magnetic fields generated by the vehicle's electrical devices and the magnetized metal in the ...tyres. The magnetic fields in cars are frequently analysed with broadband meters sensitive to a frequency range above 30Hz. This has the disadvantage that they neither detect the magnetic field of the spinning tyres nor give any information on the spectral components, which makes it impossible to adequately assess exposure. The objective of the present study was to perform spectral analyses of ELF magnetic fields in cars, to identify their frequencies, and to assess exposure based on the ICNIRP regulatory guidelines. To do this, a meter and a spectrum analyser sensitive to magnetic fields in the 5Hz–2kHz frequency range were used. Spectra were acquired for different seats, heights, and speeds, and spatially averaged exposure coefficients were calculated. The results indicated that the main emissions were detected in the 5–100Hz range, where the wheel rotation frequencies and their harmonics are found. The intensity of the rest of the emissions were negligible in comparison. The exposure quotient increases with speed, and is approximately twice as great at foot level as at head level. The magnetic field levels are lower than the reference levels (the maximum represents 3% of the ICNIRP standard), but higher than those found in residential environments and than the cut-off threshold used by the IARC to classify ELF magnetic fields in Group 2B
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•An important part of low frequency magnetic fields in cars is produced by the wheels.•Spectral analyses are required to evaluate the exposure to magnetic fields in cars.•Exposure quotients were used to characterize the exposure.•Exposure to magnetic fields generated by the wheels increases with speed.•Exposure inside cars is uneven, so that spatially averaged levels were calculated.
A comparative study was made of three methods of interpolation – inverse distance weighting (IDW), spline and ordinary kriging – after optimization of their characteristic parameters. These ...interpolation methods were used to represent the electric field levels for three emission frequencies (774kHz, 900kHz, and 1107kHz) and for the electrical stimulation quotient, QE, characteristic of complex electromagnetic environments. Measurements were made with a spectrum analyser in a village in the vicinity of medium-wave radio broadcasting antennas. The accuracy of the models was quantified by comparing their predictions with levels measured at the control points not used to generate the models. The results showed that optimizing the characteristic parameters of each interpolation method allows any of them to be used. However, the best results in terms of the regression coefficient between each model's predictions and the actual control point field measurements were for the IDW method.
•Interpolation methods were used to represent the electric field levels in a village.•Temporal variation values were less than spatial variations detected in the area.•Inverse distance weighting, spline, and ordinary kriging were compared.•The accuracy was quantified comparing the predictions with levels at control points.•The best fits between predicted and measured values corresponded to the IDW model.
The last decade has seen a rapid increase in people's exposure to electromagnetic fields. This paper reports the measurements of radiofrequency (RF) total power densities and power density spectra in ...35 towns of the region of Extremadura, Spain. The spectra were taken with three antennas covering frequencies from 100 kHz to 2.2 GHz. This frequency range includes AM/FM radio broadcasting, television, and cellular telephone signals. The power density data and transmitting antenna locations were stored in a geographic information system (GIS) as an aid in analyzing and interpreting the results. The results showed the power density levels to be below the reference level guidelines for human exposure and that the power densities are different for different frequency ranges and different size categories of towns.
Studies linking exposure to low levels of radiofrequencies with adverse health effects, notwithstanding their present apparent inconsistency, have contributed to a steady improvement in the quality ...of evaluating that exposure. In complex electromagnetic environments, with a multitude of emissions of different frequencies acting simultaneously, knowledge of the spectral content is fundamental to evaluating human exposure to non-ionizing radiation. In the present work, we quantify the most significant spectral components in the frequency band 0.5–2200 MHz in an urban area. The measurements were made with a spectrum analyzer and monopole, biconical, and log-periodic antennas. Power density levels were calculated separately for the medium wave, short wave, and frequency modulation radio broadcasting bands, and for the television and
GSM,
DCS, and
UMTS mobile telephony bands. The measured levels were compared with the
ICNIRP reference levels for exposure to multiple frequency sources for thermal effects and electrical stimulation. The results showed the criterion limiting exposure on the basis of preventing electrical stimulation of peripheral nerves and muscles to be stricter (exposure quotient 24.7 10
−
4
) than that based on thermal considerations (exposure quotient 0.16 10
−
4
). The bands that contribute most to the latter are short wave, with 46.2%, and mobile telephony with 32.6% of the total exposure.
In a complex electromagnetic environment, knowledge of the radiofrequency spectrum is essential in order to quantify the contribution of each type of emission to the public's exposure. It is also necessary to evaluate the electrical effects as well as the thermal effects because the criterion to limit exposure on the basis of the effect of the electrical stimulation of tissues is stricter than that based on thermal effects.
International guidelines for limiting exposure to electromagnetic fields set out basic restrictions and reference levels to protect human health. To ensure compliance with these guidelines, standard ...measurement procedures must be used, and assessments of the uncertainties in the measurements must be reported. Nevertheless, neither the exposure restrictions nor the technical assessment standards specify how the measurement and computation of the uncertainties should be considered. This paper analyzes the following two sources of uncertainties that are not often considered in the assessment of exposure to electromagnetic fields: 1) repeatability and 2) spatial interpolation. For this purpose, electric field measurements were made in an area in which three medium-wave radio broadcasting transmitters are located. Systematic random sampling was performed with a spectrum analyzer and a monopole-type antenna, and geostatistical techniques were used to construct contour maps of the electromagnetic radiation and its associated uncertainties. The results suggest that, in handling uncertainties in assessments of human exposure to electromagnetic fields based on spatial interpolation from point measurements, based on medium-frequency amplitude modulation broadcast transmitters, the additive approach (i.e., the uncertainty is added to the results of the assessment before the exposure level is compared to the relevant limit) is the most appropriate.
One of the aspects considered in the International Commission on Non-Ionizing Radiation Protection guidelines is that, in situations of simultaneous exposure to fields of different frequencies, ...exposure quotients for thermal and electrical stimulation effects should be examined. The aim of the present work was to analyse the electromagnetic radiation levels and exposure quotients for exposure to multiple-frequency sources in the vicinity of medium wave radio broadcasting antennas. The measurements were made with a spectrum analyser and a monopole antenna. Kriging interpolation was used to prepare contour maps and to estimate the levels in the towns and villages of the zone. The results showed that the exposure quotient criterion based on electrical stimulation effects to be more stringent than those based on thermal effects or power density levels. Improvement of dosimetry evaluations requires the spectral components of the radiation to be quantified, followed by application of the criteria for exposure to multiple-frequency sources.
Magnetic field levels were studied in an urban area--the city of Cáceres (Spain). The study included systematic spot measurements throughout the city, an analysis of the temporal variation of the ...magnetic field, and the incorporation of the data into a geographic information system. The levels detected were at most 7.3% of the ICNIRP reference levels, and the highest fields were found in the oldest neighborhoods. Considered overall, the ELF magnetic flux density levels determined in the present study were between those found in residential and in working environments. Knowledge of the levels of such fields in urban areas is therefore fundamental in evaluating the population's overall exposure, especially for people who work outdoors.
