Assessment of radio frequency exposures in schools, homes, and public places in Belgium

Characterization of exposure from emerging radio frequency (RF) technologies in areas where children are present is important. Exposure to RF electromagnetic fields (EMF) was assessed in three "sensitive" microenvironments; namely, schools, homes, and public places located in urban environments and compared to exposure in offices. In situ assessment was conducted by performing spatial broadband and accurate narrowband measurements, providing 6-min averaged electric-field strengths. A distinction between internal (transmitters that are located indoors) and external (outdoor sources from broadcasting and telecommunication) sources was made. Ninety-four percent of the broadband measurements were below 1 V m(-1). The average and maximal total electric-field values in schools, homes, and public places were 0.2 and 3.2 V m(-1) (WiFi), 0.1 and 1.1 V m(-1) (telecommunication), and 0.6 and 2.4 V m(-1) (telecommunication), respectively, while for offices, average and maximal exposure were 0.9 and 3.3 V m(-1) (telecommunication), satisfying the ICNIRP reference levels. In the schools considered, the highest maximal and average field values were due to internal signals (WiFi). In the homes, public places, and offices considered, the highestmaximal and average field values originated from telecommunication signals. Lowest exposures were obtained in homes. Internal sources contributed on average more indoors (31.2%) than outdoors (2.3%), while the average contributions of external sources (broadcast and telecommunication sources) were higher outdoors (97.7%) than at indoor positions (68.8%). FM, GSM, and UMTS dominate the total downlink exposure in the outdoor measurements. In indoor measurements, FM, GSM, and WiFi dominate the total exposure. The average contribution of the emerging technology LTE was only 0.6%

An analysis of surface integrity when drilling inconel 718 using palm oil and synthetic ester under, MQL condition

The components being manufactured in the aerospace industry must be capable of being utilized for long periods without failure. Thus, the functional behavior of these machined components is greatly dependent upon their surface integrity. The present work compares the performance of palm oil and synthetic ester on surface integrity during drilling of Inconel 718. The results indicate the substantial benefit of the minimum quantity of lubrication (MQL) by palm oil on microhardness, surface roughness, surface defects and sub-surface deformation

Interaction of Radiofrequency Radiation with Biological Systems

Rapid advancement of radiofrequency (RF)-driven technologies has greatly affected our everyday lives. Increasing evidence led by in-vitro, in-vivo studies, epidemiological and clinical trials indicates that RF interacts considerably well with biological systems in various ways depending on different exposure parameters and properties of biological materials. Besides their innumerable benefits in different sectors of commercial and military fields, they can induce alterations in many physiological functions of the body, which may culminate into adverse human health consequences. The present article explicitly addresses the RF-based technologies and their applications, fundamentals of RF energy interaction with biological systems, exposure parameters, and dosimetry studies along with thermal and non-thermal effects on different vital organs at molecular and cellular levels. Further, this article outlines the limitations of RF-induced biological effect studies, status of risk assessment, safety levels and its future perspectives

Effect of a 2.45-GHz radiofrequency electromagnetic field on neutrophil chemotaxis and phagocytosis in differentiated human HL-60 cells

The potential public health risks of radiofrequency (RF) fields have been discussed at length, especially with the use of mobile phones spreading extensively throughout the world. In order to investigate the properties of RF fields, we examined the effect of 2.45-GHz RF fields at the specific absorption rate (SAR) of 2 and 10 W/kg for 4 and 24 h on neutrophil chemotaxis and phagocytosis in differentiated human HL-60 cells. Neutrophil chemotaxis was not affected by RF-field exposure, and subsequent phagocytosis was not affected either compared with that under sham exposure conditions. These studies demonstrated an initial immune response in the human body exposed to 2.45-GHz RF fields at the SAR of 2 W/kg, which is the maximum value recommended by the International Commission for Non-Ionizing Radiation Protection (ICNIRP) guidelines. The results of our experiments for RF-field exposure at an SAR under 10 W/kg showed very little or no effects on either chemotaxis or phagocytosis in neutrophil-like human HL-60 cells

Procedure for assessment of general public exposure from Wlan in offices and in wireless sensor network testbed

A fast and accurate measurement procedure to determine experimentally wireless local area network (WLAN) radiofrequency (RF) exposure and to test compliance with international guidelines for the general public is proposed. This is the first paper where all optimal settings for the measurement equipment (sweep time, resolution bandwidth, etc.) are investigated, selected, and validated. The exposure to WLAN access points is determined for 222 locations with 7 WLAN networks present in office environments. The WLAN exposure is also characterized for the first time in a wireless sensor lab environment (WiLab) at IBBT-Ghent University in Belgium. Average background exposure to WLAN (WiLab off) is 0.12 V m(-1), with a 95(th) percentile of 0.90 V m(-1). With the WiLab in operation, average exposure increases to 1.9 V m(-1), with a 95(th) percentile of 4.7 V m(-1). All values are well below the International Commission on Non Ionizing Radiation Protection guidelines of 61 V m(-1) in the 2.4 GHz band (at least 9.1 times for distances of more than 1 m from the access points) but a significant increase of exposure is possible in WiLabs due to high duty cycles. By applying the proposed measurement method a relevant reduction in measurement time is obtained. Health Phys. 98(4):628-638; 201

Characterization of the on-body path Loss at 2.45 GHz and energy efficient WBAN design for dairy cows

Wireless body area networks (WBANs) provide promising applications in the healthcare monitoring of dairy cows. The characterization of the path loss (PL) between on-body nodes constitutes an important step in the deployment of a WBAN. In this paper, the PL between nodes placed on the body of a dairy cow was determined at 2.45 GHz. Finite-difference time domain simulations with two half-wavelength dipoles placed 20 mm above a cow model were performed using a 3-D electromagnetic solver. Measurements were conducted on a live cow to validate the simulation results. Excellent agreement between measurements and simulations was achieved and the obtained PL values as a function of the transmitter-receiver separation were well fitted by a lognormal PL model with a PL exponent of 3.1 and a PL at reference distance ( 10 cm) of 44 dB. As an application, the packet error rate ( PER) and the energy efficiency of different WBAN topologies for dairy cows (i.e., single-hop, multihop, and cooperative networks) were investigated. The analysis results revealed that exploiting multihop and cooperative communication schemes decrease the PER and increase the optimal payload packet size. The analysis results revealed that exploiting multihop and cooperative communication schemes increase the optimal payload packet size and improve the energy efficiency by 30%

Effects of Electromagnetic Fields on Mammalian Cells

The characteristics of mammalian cells can be influenced by electromagnetic fields (EMFs). The electromagnetic fields have a number of physiological effects on cells and tissues such as alteration of gene expression, cells viability, proliferation, apoptosis, number of mammospheres, cells cycle phase, and invasion. The existing literature proves that the impact of EMFs on mammalian cells depends on the density and uniformity of the field, frequency range, exposure time, cell types, culture environment, and culcuremedium. This paper presents a review of the impacts of EMFs on mammalian cells in vitro culture. In this article, we reviewed the contemporary understanding of the various form of electromagnetic radiation effect on cultured mammalian cells in vitro, EMF exposing systems, and internal field mechanism in the cells.DOI:http://dx.doi.org/10.11591/ijece.v2i2.26

Antennas And Wave Propagation In Wireless Body Area Networks: Design And Evaluation Techniques

Recently, fabrication of miniature electronic devices that can be used for wireless connectivity becomes of great interest in many applications. This has resulted in many small and compact wireless devices that are either implantable or wearable. As these devices are small, the space for the antenna is limited. An antenna is the part of the wireless device that receives and transmits a wireless signal. Implantable and wearable antennas are very susceptible to harmful performance degradation caused by the human body and very difficult to integrate, if not designed properly. A designer need to minimize unwanted radiation absorption by the human body to avoid potential health issues. Moreover, a wearable antenna will be inevitably exposed to user movements and has to deal with influences such as crumpling and bending. These deformations can cause degraded performance or a shifted frequency response, which might render the antenna less effective. The existing wearable and implantable antennas’ topologies and designs under discussion still suffer from many challenges such as unstable antenna behavior, low bandwidth, considerable power generation, less biocompatibility, and comparatively bigger size. The work presented in this thesis focused on two main aspects. Part one of the work presents the design, realization, and performance evaluation of two wearable antennas based on flexible and textile materials. In order to achieve high body-antenna isolation, hence, minimal coupling between human body and antenna and to achieve performance enhancement artificial magnetic conductor is integrated with the antenna. The proposed wearable antennas feature a small footprint and low profile characteristics and achieved a wider -10 dB input impedance bandwidth compared to wearable antennas reported in literature. In addition, using new materials in wearable antenna design such as flexible magneto-dielectric and dielectric/magnetic layered substrates is investigated. Effectiveness of using such materials revealed to achieve further improvements in antenna radiation characteristics and bandwidth and to stabilize antenna performance under bending and on body conditions compared to artificial magnetic conductor based antenna. The design of a wideband biocompatible implantable antenna is presented. The antenna features small size (i.e., the antenna size in planar form is 2.52 mm3), wide -10 dB input impedance bandwidth of 7.31 GHz, and low coupling to human tissues. In part two, an overview of investigations done for two wireless body area network applications is presented. The applications are: (a) respiratory rate measurement using ultra-wide band radar system and (b) an accurate phase-based localization method of radio frequency identification tag. The ultimate goal is to study how the antenna design can affect the overall system performance and define its limitations and capabilities. In the first studied application, results indicate that the proposed sensing system is less affected and shows less error when an antenna with directive radiation pattern, low cross-polarization, and stable phase center is used. In the second studied application, results indicate that effects of mutual coupling between the array elements on the phase values are negligible. Thus, the phase of the reflected waves from the tag is mainly determined by the distance between the tag and each antenna element, and is not affected by the induced currents on the other elements