Carla Oliveira

Viscosity Measurements of Liquid Toluene at Low Temperatures Using a Dual Vibrating-Wire Technique

A recently developed dual vibrating-wire technique has been used to perform viscosity measurements of liquid toluene in the temperature range 213 K≤T≤298 K, and at pressures up to approximately 20 MPa. The results were obtained by operating the vibrating-wire sensor in both forced and free decay modes. The estimated precision of the viscosity measurements, in either mode of operation, is ±0.5%, for temperatures above or equal to 273 K, increasing with decreasing temperature up to ±1% at 213 K. The corresponding overall uncertainty is estimated to be within ±1% and ±1.5%, respectively.

An Off-Body Channel Model for Body Area Networks in Indoor Environments

This paper presents an off-body channel model for body area networks (BANs) in indoor environments. The proposed model, which is based on both simulations and measurements in a realistic environment, consists of three components: mean path loss, body shadowing, and multipath fading. Seven scenarios in a realistic indoor office environment containing typical scatterers have been measured: five were static (three standing and two sitting) and two dynamic (walk in a fixed place and real walk). The measurement equipment and measurement procedures are described. The mean path loss component is modeled as a log function of distance, the path loss exponent being in the range between 0.4 and 1.6, while a statistical perspective is taken for the other two components, i.e., body shadowing is found to be well modeled by a log normal distribution and multipath fading by Rice or Nakagami-m distributions, depending on body motion characteristics. The correlation between the selected distributions and empirical data is not lower than 0.95, typically being greater than 0.98. The novelty of this model is that it takes the statistical influence of various parameters and features present in BANs into account, such as body influence, placement of the wearable antennas, user orientation in the environment, dynamism of the BAN scenario, and propagation conditions.

Radiation Pattern of Wearable Antennas: A Statistical Analysis of the Influence of the Human Body

This paper explores a statistical approach for modelling antennas’ behaviour in the vicinity of the human body. The statistics of radiation patterns, i.e., average and standard deviation, have been calculated for Uniform and Rayleigh distance Distributions of the antenna to the body. The coupling between the body and the antenna, and the reduction of antenna efficiency, lead to a distortion of the radiation pattern, which depends on the distance as well as on the location on the body. A patch antenna operating at 2.45xa0GHz, on the head, chest, arm, and leg was simulated in computer simulation technology (CST), using a voxel model. Results show that the relative change of the average radiation pattern for an antenna located on the chest can reach 24xa0%. The study was complemented with measurements, showing that, in the area of interest for on-body communications, an average difference between CST and measurements of 0.9xa0dB is found which can be considered very good.

A statistical analysis of the influence of the human body on the radiation pattern of wearable antennas

This paper introduces a statistical approach for modelling antennas behaviour in the vicinity of the human body. The statistics of radiation patterns, i.e., average and standard deviation, have been calculated for Uniform and Rayleigh antenna to body distance distributions. The coupling between the body and the antenna and reduction of antenna efficiency leads to the distortion of the antenna radiation pattern, which depends on the distance as well as on the location on the body. A patch antenna operating at 2.45 GHz was simulated in CST, near to regions of a voxel human model, i.e., Head, Chest, Arm and Leg. Results show that the relative change of the average radiation pattern for an antenna located on the Chest can reach 24%.

The moniT Project: Electromagnetic Radiation Exposure Assessment in Mobile Communications

The monIT project provides public information on population exposure to electromagnetic fields (EMF) from mobile communication systems in Portugal. The monitoring system is based on a network of autonomous remote probing stations, and also on an extensive EMF sounding program, both carried out in public areas across the country. Measured results are automatically uploaded to a Web site for public dissemination (http://www.lx.it.pt/monit), which also includes other relevant information about EMF for the general public. This paper describes the projects structure, the automatic monitoring system, the projects activities, and, finally, it presents a brief analysis of the measured results

Education for sustainable development in higher education: evaluating coherence between theory and praxis

Universities are an important part of the process of change taking place in society. However, this is often overshadowed by these institutions giving priority to technocratic models in the relationship between science and society. In this context, according to Habermas, theories can serve to clarify practical questions and guide praxis into the right actions (social emancipation and rational autonomy). Habermas introduces the need to evaluate the particular contexts in which scientific arguments are made and assessed. The aim of this study was to develop a set of assessment criteria for education for sustainable development in higher education curricula. These were developed in line with Habermas by introducing further adaptions within the context of education for sustainable development. These criteria were tested in a blended learning master’s programme in Environmental Citizenship and Participation at the Universidade Aberta, Portugal. The following research tools were used as follows: (i) a questionnaire survey to the graduates; (ii) content analysis applied to the information guide and to the abstracts of the dissertations that were produced. The case study revealed that an absence of theoretical frameworks could lead to inconsistencies between theory and praxis. Improvements to curricula are then drawn from this study.

A Statistical Model to Characterize User Influence in Body Area Networks

The main goal of this work is to characterize users influence in Body Area Networks, endeavoring to provide useful statistical values for channel models. Well-known theoretical models are used to obtain the fields produced by a plane wave or a point source near a circular dielectric cylinder (as a simple approach for the human body). A statistical analysis on the impact of the body for the source located at different distances is done. Modifications in the radiation patterns are found, ranging up to 30 dB, for instance, for a source located from 0 to 10 cm off the body.

Characterizing On-Body Wireless Sensor Networks

The main goal of this work is to characterise communications through body area networks (BANs), analysing how the human body affects wireless links qualities. 802.15.4 MICAz motes were deployed on seven on-body locations of four volunteers and a test-dummy. The quality of the communications was monitored in order to study the channel behaviour. Results show that the human body clearly modifies communication properties, introducing attenuations of up to 26 dB. Differences between male and female subjects were found to be unimportant. Body posture affects the performance, mainly because of body shadowing. LoS together with the channels dynamic nature are key issues to achieve connectivity. Power settings and the local environment also influence the BANs performance.

Modelling on- and off-body channels in Body Area Networks

This paper presents an analysis of the capacity of a 2×2 MIMO system in on- and off-body communications in an indoor multipath environment. The modelling of wearable antennas in Body Area Networks (BANs) has been separated into antennas in the vicinity of the body (full wave simulations), including body dynamics (taken from motion capture analysis), and the environment (clusters of scatterers). A Geometrically Based Statistical Channel model adapted to the BANs environment is used. Based on proper metrics, optimum 2×2 antenna placements are suggested. The best performance is obtained when the on-body sink is on the front and back of the body, and data sensors are on the head, with a capacity gain of 0.97. This sink configuration also enables a good connectivity with an external base station (the capacity gain reaches 0.83).

Integrating Sustainability into the University: Past, Present, and Future

The idea of evolution is deeply rooted in Western culture as since the eighteenth century the concept of continual development. Indeed, the latter commenced with the Industrial Revolution with the intent of improving the standard of living and thus quality of life. Higher education is necessarily part of this requirement and has been enacted by Universities that provide graduate whom typically become active and responsible citizens often internationally and usually supported by Government. To an extent, Universities control education, research, and training and thus provide a pivotal role in the dissemination of any concept. In this chapter, we examine the concept of sustainability and, based on an analysis, demonstrate the historical significance of sustainability and outline the significant contribution made by Universities with regard to the elucidation of sustainability. Indeed, it is our perception that Universities should use the concepts of both sustainable development and sustainability to reinforce their mission and improve the quality of the learning process. Although the University is seen as the most traditional of all institutions, it has of late become the major instrument of change in social, economic, and political systems, by adopting a new educational paradigm based on multidisciplinary education concerning environmental issues, stressing the values of equity, justice, cultural, and environmental sustainability, and viewing the learning process itself as lifelong.