RF Exposure Analysis for Multiple Wi-Fi Devices In Enclosed Environment

Wi-Fi devices operated inside a metallic enclosure have been investigation in the recent years. A motivation for this study is to investigate wave propagation inside an enclosed environment such as elevator, car, aircraft, and spacecraft. There are performances and safety concerned that when the RF transmitters are used in the metallic enclosed environments. In this paper, the field distributions inside a confined room were investigated with multiple portable Wi-Fi devices. Computer simulations were performed using the rigorous computational electromagnetics (CEM). The method of moments (MoM) was used to model the mutual coupling among antennas. The geometrical theory of diffraction (GTD) was applied for the multiple reflections off the ground and walls. The prediction of the field distribution inside such environment is useful for the planning and deployment of a wireless radio and sensor system. Factors that affect the field strengths and distributions of radio waves in confined space were analyzed. The results could be used to evaluate the RF exposure safety in confined environment. By comparing the field distributions for various scenarios, it was observed that the Wi-Fi device counts, spacing and relative locations in the room are important factors in such environments. The RF Keep Out Zone (KOZ), where the electric field strengths exceed the permissible RF exposure limit, could be used to assess the RF human exposure compliance. As shown in this study, it s possible to maximize or minimize field intensity in specific area by arranging the Wi-Fi devices as a function of the relative location and spacing in a calculated manner

Evaluation of electric and magnetic fields distribution and SAR induced in 3D models of water containers by radiofrequency radiation using FDTD and FEM simulation techniques

In this study, two software packages using different numerical techniques FEKO 6.3 with Finite-Element Method (FEM) and XFDTD 7 with Finite Difference Time Domain Method (FDTD) were used to assess exposure of 3D models of square, rectangular, and pyramidal shaped water containers to electromagnetic waves at 300, 900, and 2400 MHz frequencies. Using the FEM simulation technique, the peak electric field of 25, 4.5, and 2 V/m at 300 MHz and 15.75, 1.5, and 1.75 V/m at 900 MHz were observed in pyramidal, rectangular, and square shaped 3D container models, respectively. The FDTD simulation method confirmed a peak electric field of 12.782, 10.907, and 10.625 V/m at 2400 MHz in the pyramidal, square, and rectangular shaped 3D models, respectively. The study demonstrated an exceptionally high level of electric field in the water in the two identical pyramid shaped 3D models analyzed using the two different simulation techniques. Both FEM and FDTD simulation techniques indicated variations in the distribution of electric, magnetic fields, and specific absorption rate of water stored inside the 3D container models. The study successfully demonstrated that shape and dimensions of 3D models significantly influence the electric and magnetic fields inside packaged materials; thus, specific absorption rates in the stored water vary according to the shape and dimensions of the packaging materials.Comment: 22 pages, 30 figures and 2 table

Human exposure to electromagnetic fields from WLANs and WBANs in the 2.4 GHz band

226 p.En los últimos años, el masivo crecimiento de las comunicaciones inalámbricas ha incrementado la preocupación acerca de la exposición humana a los campos electromagnéticos debido a los posibles efectos sobre la salud. Esta tesis surge de la necesidad de proporcionar información acerca de este tipo de exposición desde un punto de vista técnico. Por una parte, se han estudiado los niveles de exposición causados por señales WiFi, para lo cual ha sido necesario establecer un procedimiento de medida adecuado para tomar muestras de estas emisiones. Además, se han llevado a cabo campañas de medida para evaluar la exposición a señales WiFi y su variabilidad en el interior de un entorno público. Por otra parte, se ha analizado la potencia absorbida por el cuerpo humano a causa de los novedosos dispositivos wearables. Se han implementado dos antenas de este tipo, apropiadas para dispositivos wearables, se ha analizado detalladamente la exposición debida a estos aparatos y finalmente se han comparado los niveles de exposición producidos por estas antenas y por las señales WiFi

Human exposure to electromagnetic fields from WLANs and WBANs in the 2.4 GHz band

226 p.En los últimos años, el masivo crecimiento de las comunicaciones inalámbricas ha incrementado la preocupación acerca de la exposición humana a los campos electromagnéticos debido a los posibles efectos sobre la salud. Esta tesis surge de la necesidad de proporcionar información acerca de este tipo de exposición desde un punto de vista técnico. Por una parte, se han estudiado los niveles de exposición causados por señales WiFi, para lo cual ha sido necesario establecer un procedimiento de medida adecuado para tomar muestras de estas emisiones. Además, se han llevado a cabo campañas de medida para evaluar la exposición a señales WiFi y su variabilidad en el interior de un entorno público. Por otra parte, se ha analizado la potencia absorbida por el cuerpo humano a causa de los novedosos dispositivos wearables. Se han implementado dos antenas de este tipo, apropiadas para dispositivos wearables, se ha analizado detalladamente la exposición debida a estos aparatos y finalmente se han comparado los niveles de exposición producidos por estas antenas y por las señales WiFi

Exploring potential benefits and challenges of touch screens on the flight deck

As the avionics industry is seeking to introduce touch screens into most flight decks, it is vital to understand the interactional challenges and benefits of doing so. The potential benefits and challenges of touch screen technology on flight decks was investigated by means of a variety of qualitative and quantitative research methods (mixed methods approach). A number of research questions are addressed, which have been iteratively developed from the literature, interviews with avionics experts and pilots. This work presents one field study, two lab studies, one observational study, one simulation study and one comparative user study, all investigating various factors/variables that could affect touch screen usability on the flight deck. The first field study investigated interactive displays on the flight deck with search and rescue (SAR) crew members in an operational setting in helicopters. This was the first in-flight experiment where touch screens were evaluated under real conditions. The results showed the impact of target size, device placement and in-flight vibration on targeting accuracy and performance. Presented statistical analyses and observations are essential to understand how to design effective touch screen interfaces for the flight deck. One of the lab studies evaluated (more in depth) the potential impact of display position of touch screens within a simulated cockpit. This was the first experiment that investigated the impact of various display positions on performance following Fitts’ Law experiment. Results revealed that display location has a significant impact on touch screen usability. Qualitative findings from semi-structured interviews and post-experiment questionnaires supported the understanding of interactional issues on a flight deck environment which extended initial design guidelines. Pilots brought attention to the impact of increased G-force (+Gz) as an additional environmental factor that might affect touch screen usability on agile aircrafts. Therefore, a Fitts’ law experiment was conducted to understand the effect of +Gz on touch screen usability. +Gz conditions were simulated with a weight-adjustable wristband, which was the first approach to simulate increased G-force in lab environment. Empirical results and subjective ratings showed a large impact of +Gz on performance and fatigue indices. An observational study focused on Electronic Flight Bag (EFB) (mobile device) usage on the specific domain of Search and Rescue (SAR) helicopters. The novelty in this study was the focus group in which the aim was to find features, content and functionality that a SAR pilot may wish to see in an EFB. From operational observations and interviews with pilot’s operational requirements were defined. A Digital Human Modelling Software was used to define physical constraints of an EFB and develop interface design guidelines. A scenario and virtual prototype was created and presented to pilots. A new way of interaction to manipulate radio frequencies of avionics systems was developed based on findings achieved in this work and other relevant studies. A usability experiment simulating departures and approaches to airports was used to evaluate the interface and compare it with the current system (Flight Management System). In addition, interviews with pilots were conducted to find out their personal impressions and to reveal problem areas of the interface. Analyses of task completion time and error rates showed that the touch interface is significantly faster and less prone to user input errors than the conventional input method (via physical or virtual keypad). Potential problem areas were identified and an improved interface is suggested. Overall, the main contribution of this research is a framework showing the relation between various aspects that could impact the usability of touch screens on the flight deck. Furthermore, design guidelines were developed that should support the usability of interactive displays on the flight deck. This work concludes with a preliminary questionnaire that can help avionic designers to evaluate whether a touch screen is an appropriate user interface for their system

Exploring potential benefits and challenges of touch screens on the flight deck

As the avionics industry is seeking to introduce touch screens into most flight decks, it is vital to understand the interactional challenges and benefits of doing so. The potential benefits and challenges of touch screen technology on flight decks was investigated by means of a variety of qualitative and quantitative research methods (mixed methods approach). A number of research questions are addressed, which have been iteratively developed from the literature, interviews with avionics experts and pilots. This work presents one field study, two lab studies, one observational study, one simulation study and one comparative user study, all investigating various factors/variables that could affect touch screen usability on the flight deck. The first field study investigated interactive displays on the flight deck with search and rescue (SAR) crew members in an operational setting in helicopters. This was the first in-flight experiment where touch screens were evaluated under real conditions. The results showed the impact of target size, device placement and in-flight vibration on targeting accuracy and performance. Presented statistical analyses and observations are essential to understand how to design effective touch screen interfaces for the flight deck. One of the lab studies evaluated (more in depth) the potential impact of display position of touch screens within a simulated cockpit. This was the first experiment that investigated the impact of various display positions on performance following Fitts’ Law experiment. Results revealed that display location has a significant impact on touch screen usability. Qualitative findings from semi-structured interviews and post-experiment questionnaires supported the understanding of interactional issues on a flight deck environment which extended initial design guidelines. Pilots brought attention to the impact of increased G-force (+Gz) as an additional environmental factor that might affect touch screen usability on agile aircrafts. Therefore, a Fitts’ law experiment was conducted to understand the effect of +Gz on touch screen usability. +Gz conditions were simulated with a weight-adjustable wristband, which was the first approach to simulate increased G-force in lab environment. Empirical results and subjective ratings showed a large impact of +Gz on performance and fatigue indices. An observational study focused on Electronic Flight Bag (EFB) (mobile device) usage on the specific domain of Search and Rescue (SAR) helicopters. The novelty in this study was the focus group in which the aim was to find features, content and functionality that a SAR pilot may wish to see in an EFB. From operational observations and interviews with pilot’s operational requirements were defined. A Digital Human Modelling Software was used to define physical constraints of an EFB and develop interface design guidelines. A scenario and virtual prototype was created and presented to pilots. A new way of interaction to manipulate radio frequencies of avionics systems was developed based on findings achieved in this work and other relevant studies. A usability experiment simulating departures and approaches to airports was used to evaluate the interface and compare it with the current system (Flight Management System). In addition, interviews with pilots were conducted to find out their personal impressions and to reveal problem areas of the interface. Analyses of task completion time and error rates showed that the touch interface is significantly faster and less prone to user input errors than the conventional input method (via physical or virtual keypad). Potential problem areas were identified and an improved interface is suggested. Overall, the main contribution of this research is a framework showing the relation between various aspects that could impact the usability of touch screens on the flight deck. Furthermore, design guidelines were developed that should support the usability of interactive displays on the flight deck. This work concludes with a preliminary questionnaire that can help avionic designers to evaluate whether a touch screen is an appropriate user interface for their system

Aerospace medicine and biology, an annotated bibliography. volume xi- 1962-1963 literature

Aerospace medicine and biology - annotated bibliography for 1962 and 196

Federal Register

Daily publication of the U.S. Office of the Federal Register contains rules and regulations, proposed legislation and rule changes, and other notices, including "Presidential proclamations and Executive Orders, Federal agency documents having general applicability and legal effect, documents required to be published by act of Congress, and other Federal agency documents of public interest" (p. ii). Table of Contents starts on page iii

Bowdoin Orient v.103, no.1-23 (1973-1974)

https://digitalcommons.bowdoin.edu/bowdoinorient-1970s/1004/thumbnail.jp

1990-1995 Brock Campus News

A compilation of the administration newspaper, Brock Campus News, for the years 1990 through 1995. It had previously been titled The Blue Badger