| 1. |
- Chedid, Michel, 1977-, et al.
(författare)
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Electromagnetic Coupling To a Wearable Application Based On Coaxial Cable Architecture
- 2006
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Ingår i: Progress In Electromagnetics Research, PIER. - 1070-4698. ; 56, s. 109-128
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Tidskriftsartikel (refereegranskat)abstract
- A radiated susceptibility problem has been identified and solved by means of simulations for a wearable computer system in the frequency range 30 MHz – 1 GHz. Simulation strategy is presented for analyzing the effects induced by an electromagnetic plane wave within the system comprising infra-red sensors connected by coaxial cables. A procedure of creating a TLM model of the coaxial cable with controlled electromagnetic coupling characteristics on a coarse grid is proposed. Results are verified by means of theoretical calculations. Different sensor enclosures and filtering circuits are analyzed and implemented to meet the hard electromagnetic compatibility requirements while not interfering with the functionality of the wearable application.
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| 2. |
- Chedid, Michel, 1977-, et al.
(författare)
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Evaluation of Conductive Textile for Wearable Computer Applications
- 2006
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Ingår i: The IMAPS Nordic Annual Conference. - 9519800298 ; , s. 220-227
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Konferensbidrag (refereegranskat)abstract
- Wearable systems put high demands on wearability and robustness. Conductive fabrics are very likely to be used in wearable systems due to their textile-like characteristics. However conductive fabrics must be able to resist environmental stresses (wearing, laundering, etc.) in the same way as clothing in order to fully comply with the requirements. A demonstrator, TxWear, was constructed to exploit conductive fabrics in building a conductive textile transmission line for intermodular communication and power transmission (DC power line communication bus), thus eliminating the need for cables between the modules. The hardware modules are connected to the conductive line through connectors from textile industry, i.e., snap fasteners. Different types of conductive fabrics (Ni/Cu plated polyester fabrics and stainless-steel based elastic ribbon) were evaluated and compared according to their conductivity, flexibility and robustness characteristics. The effect of washing on the electrical properties (per-unit-length parameters) of the textile transmission line was studied. Different coating processes, i.e., parylene and silicone coating, were studied and evaluated in order to isolate and enhance the robustness of the conductive textile. Ni/Cu plated polyester ripstop fabric was found to be not appropriate for wearable applications, while conductive elastic ribbon showed good robustness to laundry induced stresses.
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| 3. |
- Chedid, Michel, 1977-, et al.
(författare)
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Experimental Analysis and Modelling of Textile Transmission Line for Wearable Applications
- 2007
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Ingår i: International Journal of Clothing Science and Technology. - : Emerald Group Publishing Limited. - 0955-6222 .- 1758-5953. ; 19:1, s. 59-71
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Tidskriftsartikel (refereegranskat)abstract
- Purpose – By means of measurement and modelling, evaluate frequency dependent per-unit-length parameters of conductive textile transmission line (CTTL) for wearable applications and study deterioration of these parameters when CTTL is subjected to washing. Design/methodology/approach – The studied transmission line is made of Nickel/Copper (Ni/Cu) plated polyester ripstop fabric and is subjected to standard 60oC cycle in a commercial off-the-shelf washing machine. The per-unit-length parameters (resistance and inductance) and characteristic impedance of the line are extracted from measurements before and after washing. Using the measurement data an equivalent circuit is created to model the degradation of the line. The circuit is then integrated in a three-dimensional Transmission Line Matrix (TLM) model of the transmission line. Findings – Both an electrical equivalent circuit and a TLM model are developed describing the degradation of the conductive textile when washed. A severe deterioration of the electrical parameters of the line is noticed. Experimental and modelling results are in good agreement in the addressed frequency band. Research limitations/implications – Analysis is performed for frequencies up to 10 MHz. The developed TLM model can be used to conduct parametric studies of the CTTL. To counteract the degradation of the line, protective coating is to be considered in further studies. Originality/value – Experimental and simulation based characterization of the conductive textile transmission line when subjected to washing cycles.
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| 4. |
- Chedid, Michel, 1977-, et al.
(författare)
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Low Power High Bandwidth Power-Line Communication Network for Wearable Applications
- 2010
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A DC power-line communication (PLC) network for wearable applications is proposed and studied. The DC-PLC network enhances wearability compared to other types of wired networks by requiring minimum amount of wiring. The DC-PLC transceiver is designed based on a low power high bandwidth active inductance circuit, thus not jeopardizing the low power property of the wired solution. The DC-PLC network is implemented in a wearable application and compared to a wireless wearable network by studying and comparing the bit-energy of these networks. The bitenergy study is based on a statistical model of the communication where message size and rate, preamble time and power measurements are included. The DC-PLC network showed shorter latency and lower bit-energy compared to the wireless alternatives when preamble time is kept at reasonable level.
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| 5. |
- Chedid, Michel, 1977-, et al.
(författare)
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Modelling and Characterization of Electrostatic Current Noise Induced Mechanically in Wired Wearable Applications
- 2010
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Ingår i: Journal of Electrostatics. - : Elsevier BV. - 0304-3886 .- 1873-5738. ; 68:1, s. 21-26
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Tidskriftsartikel (refereegranskat)abstract
- By means of statistical modelling and measurement, the triboelectric current noise spectral density is evaluated for shielded cables in body-borne wired network subjected to mechanical stresses. Assuming a shot noise model, an expression for the current spectral density of the noise is derived. The efficiency of the methodology is demonstrated by measuring the triboelectric current noise in two shielded cables subjected to bending. Thereafter the parameters of the noise pulses’ waiting time and amplitude probability density functions are extracted from measurement, thus enabling the computation of the current spectral density of the noise induced mechanically in body-borne wired networks.
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| 6. |
- Chedid, Michel, 1977-, et al.
(författare)
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Realization of an active inductance for a low power high bandwidth DC power line communication network transceiver
- 2010
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Ingår i: AEU - International Journal of Electronics and Communications. - : Elsevier. - 1434-8411 .- 1618-0399. ; 64:10, s. 947-952
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Tidskriftsartikel (refereegranskat)abstract
- An active inductor based on an improved gyrator circuit is proposed. The active inductor is developed to be implemented in a high impedance transceiver for a wearable DC power line communication network where requirements such as low power consumption, high bandwidth and numerous nodes support are prioritized. A load isolation step is introduced to ensure the stability of the active inductance's size on different load currents. The proposed gyrator circuit is analyzed and optimized by means of theoretical calculations. The theoretical results are then verified by simulations and experiments in the frequency range up to 10MHz.
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| 7. |
- Chedid, Michel, 1977-, et al.
(författare)
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Roadmap : Wearable Computers
- 2005
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Ingår i: Proceedings of IMAPS Nordic Annaul Conference. - 9519800271 - 951980028X ; , s. 146-154
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Konferensbidrag (refereegranskat)abstract
- The diversity of portable products on the market has increased due to the evolution of electronic components and batteries. A migration of the portable products into wearable has started by applying non-conventional user interfaces such as voice and gesture recognition, to enable hand-free use. However, major issues remain to be solved in order to make the transition complete. Key technological domains that affect the development of wearable systems are described and discussed. A review of different existing portable/wearable applications and domain of use is presented. User and environmental requirements to be applied on future wearable systems are identified. One of the major user concerns is the robustness of the system, which should withstand the stresses implied by the human body. Therefore, research is made to exploit the advantages of conductive textiles in order to build robust wearable architecture.
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| 8. |
- Chedid, Michel, 1977-
(författare)
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Wearable Systems in Harsh Environments : Realizing New Architectural Concepts
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Wearable systems continue to gain new markets by addressing improved performance and lower size, weight and cost. Both civilian and military markets have incorporated wearable technologies to enhance and facilitate user's tasks and activities. A wearable system is a heterogeneous system composed of diverse electronic modules: data processing, input and output modules. The system is constructed to be body-borne and therefore, several constraints are put on wearable systems regarding wearability (size, weight, placement, etc.) and robustness rendering the task of designing wearable systems challenging. In this thesis, an overview of wearable systems was given by discussing definition, technology challenges, market analysis and design methodologies. Main research targeted at network architectures and robustness to environmental stresses and electromagnetic interference (EMI). The network architecture designated the data communication on the intermodule level - topology and infrastructure. A deeper analysis of wearable requirements on the network architecture was made and a new architecture is proposed based on DC power line communication network (DC-PLC). In addition, wired data communication was compared to wireless data communication by introducing statistical communication model and looking at multiple design attributes: power efficiency, scalability, and wearability.The included papers focused on wearable systems related issues including analysis of present situation, environmental and electrical robustness studies, theoretical and computer aided modelling, and experimental testing to demonstrate new wearable architectural concepts. A roadmap was given by examining the past and predicting the future of wearable systems in terms of technology, market, and architecture. However, the roadmap was updated within this thesis to include new market growth figures that proved to be far less than was predicted in 2004. User and application environmental requirements to be applied on future wearable systems were identified. A procedure is presented to address EMI and evaluated solutions in wearable application through modelling and simulation. Environmental robustness and wearability of wearable systems in general, and washability and conductive textile in particular are investigated. A measurement-based methodology to model electrical properties of conductive textile when subjected to washing was given.Employing a wired data communication network was found to be more appropriate for wearable systems than wireless networks when prioritizing power efficiency. The wearability and scalability of the wired networks was enhanced through conductive textile and DC-PLC, respectively. A basic wearable application was built to demonstrate the suitability of DC-PLC communication with conductive textile as infrastructure. The conductive textile based on metal filament showed better mechanical robustness than metal plated conductive textile. A more advanced wearable demonstrator, where DC-PLC network was implemented using transceivers, further strengthened the proposed wearable architecture. Based on the overview, the theoretical, modelling and experimental work, a possible approach of designing wearable systems that met several contradicting requirements was given.
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| 9. |
- Rattfält, Linda, 1979-, et al.
(författare)
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Electrical Properties of Textile Electrodes
- 2007
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Ingår i: Engineering in Medicine and Biology Society, 2007. EMBS 2007. - : IEEE. - 9781424407873 ; , s. 5735-5738
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Konferensbidrag (refereegranskat)abstract
- In this study we aim to explain the behavior of textile electrodes due to their construction techniques. Three textile electrodes were tested for electrode impedance and polarization potentials. The multifilament yarn (A) is favorable for its low thread resistance. Although, when knitted into electrodes, the staple fiber yarn (B) showed a comparable and satisfiable electrode impedance. The multifilament yarn had however a lower polarization potential drift then the other specimens. The monofilament yarn (C) had high electrode impedance and varying mean polarization potentials due to its conductive material and small contact area with the skin.
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| 10. |
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