| 1. |
- Akbari, Saba, et al.
(författare)
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Capacitance Modelling of Conductive Cotton Knit Fabric for Sensor Node Communication
- 2024
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Ingår i: 2024 13TH MEDITERRANEAN CONFERENCE ON EMBEDDED COMPUTING, MECO 2024. - : IEEE. - 9798350387568 - 9798350387575 ; , s. 398-402
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Konferensbidrag (refereegranskat)abstract
- Applications of sensor nodes in our daily lives are increasing. Sensor nodes can be embedded in textiles to monitor various environmental parameters or to measure biomarkers. Embedded nodes in fabrics can use wires as means of communication. This approach, however, has drawbacks in terms of reliability, e.g. wire breaks, and discomfort that can arise in a large fabric network with multitudes of cables. Power-line communication (PLC) can mitigate these problems by using conductive planes instead of wires. However, the capacitance formed as a result of using two parallel plates and fabric in between attenuates the signal transmission between sensor nodes. Therefore, in order to compensate the attenuation effect of the conductive fabric which can be achieved by optimizing the hardware, we need to know the capacitance model of the conductive fabric. In our case it is necessary to know the capacitance model as a result of placing a cotton knit fabric between conductive meshes. In this work, we demonstrate that one can use the parallel plate capacitance model for estimating the capacitance of a cotton knit fabric placed between two conductive meshes.
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| 2. |
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| 3. |
- Akbari, Saba, et al.
(författare)
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Development of Energy Autonomous Wearable Sensor Node for Oxygen Monitoring in Underground Tunnels
- 2024
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Ingår i: 2024 13TH MEDITERRANEAN CONFERENCE ON EMBEDDED COMPUTING, MECO 2024. - : IEEE. - 9798350387568 - 9798350387575 ; , s. 394-397
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Konferensbidrag (refereegranskat)abstract
- Underground tunnels contain toxic, hazardous gases or lack oxygen. Therefore, providing the safety of personnel working in underground tunnels by monitoring oxygen, combustible or toxic gases is important. Wearable sensor networks are used in various applications such as oxygen monitoring. Some wearable sensor networks for gas monitoring are powered by batteries. Given the finite lifetime of batteries and the long term stay of underground personnel in these places, e.g. as a result of incidents, having a wearable sensor node with a stable power supply is crucial to conducting oxygen monitoring and notifying the emergency conditions. In order to provide a battery-less operation of the wearable sensor node, one approach is to use ambient energy sources. Considering the fact that the human body can survive only a few minutes without oxygen, the goal of our work is to investigate whether the power generated as a result of temperature difference between the body and ambient air is sufficient to power a sensor node for conducting oxygen detection every 20 seconds. Therefore, we present the development of a wearable sensor node for oxygen detection. The platform consists of a thermoelectric generator (TEG) converter, a sensing circuit for an electrochemical gas sensor and a power management circuit. Our experimental results with our platform indicate that a temperature difference of 6 degrees C between the body and the ambient air and storing the harvested energy in a capacitor ensure the autonomous operation of the wearable sensor node for measurements and alarm actuation conducted every 15 seconds. The period between the measurements could even become less than 15 seconds in underground tunnels as the temperature difference increases.
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| 5. |
- Al Nahas, Beshr, 1985, et al.
(författare)
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Low-power listening goes multi-channel
- 2014
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Ingår i: Proceedings - IEEE International Conference on Distributed Computing in Sensor Systems, DCOSS 2014. ; , s. 2-9
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Konferensbidrag (refereegranskat)abstract
- Exploiting multiple radio channels for communication has been long known as a practical way to mitigate interference in wireless settings. In Wireless Sensor Networks, however, multi-channel solutions have not reached their full potential: the MAC layers included in TinyOS or the Contiki OS for example are mostly single-channel. The literature offers a number of interesting solutions, but experimental results were often too few to build confidence. We propose a practical extension of low-power listening, MiCMAC, that performs channel hopping, operates in a distributed way, and is independent of upper layers of the protocol stack. The above properties make it easy to deploy in a variety of scenarios, without any extra configuration/scheduling/channel selection hassle. We implement our solution in Contiki and evaluate it in a 97-node~testbed while running a complete, out-of-the-box low-power IPv6 communication stack (UDP/RPL/6LoWPAN). Our experimental results demonstrate increased resilience to emulated WiFi interference (e.g., data yield kept above 90% when Contiki MAC drops in the 40% range). In noiseless environments, MiCMAC keeps the overhead low in comparison to Contiki MAC, achieving performance as high as 99% data yield along with sub-percent duty cycle and sub-second latency for a 1-minute inter-packet interval data collection. © 2014 IEEE.
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| 6. |
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| 7. |
- Asad, H. A., et al.
(författare)
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On Securing Persistent State in Intermittent Computing
- 2020
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Ingår i: ENSsys 2020 - Proceedings of the 8th International Workshop on Energy Harvesting and Energy-Neutral Sensing Systems. - New York, NY, USA : Association for Computing Machinery, Inc. ; , s. 8-14, s. 8-14, s. 8-14
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Konferensbidrag (refereegranskat)abstract
- We present the experimental evaluation of different security mechanisms applied to persistent state in intermittent computing. Whenever executions become intermittent because of energy scarcity, systems employ persistent state on non-volatile memories (NVMs) to ensure forward progress of applications. Persistent state spans operating system and network stack, as well as applications. While a device is off recharging energy buffers, persistent state on NVMs may be subject to security threats such as stealing sensitive information or tampering with configuration data, which may ultimately corrupt the device state and render the system unusable. Based on modern platforms of the Cortex M*series, we experimentally investigate the impact on typical intermittent computing workloads of different means to protect persistent state, including software and hardware implementations of staple encryption algorithms and the use of ARM TrustZone protection mechanisms. Our results indicate that i) software implementations bear a significant overhead in energy and time, sometimes harming forward progress, but also retaining the advantage of modularity and easier updates; ii) hardware implementations offer much lower overhead compared to their software counterparts, but require a deeper understanding of their internals to gauge their applicability in given application scenarios; and iii) TrustZone shows almost negligible overhead, yet it requires a different memory management and is only effective as long as attackers cannot directly access the NVMs.
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| 8. |
- Asan, Noor Badariah, 1984-, et al.
(författare)
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Effect of Thickness Inhomogeneity in Fat Tissue on In-Body Microwave Propagation
- 2018
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Ingår i: Proceedings of the 2018 IEEE/MTT-S International Microwave Biomedical Conference (IMBIOC). - Philadelphia, USA : IEEE. - 9781538659182 ; , s. 136-138
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Konferensbidrag (refereegranskat)abstract
- In recent studies, it has been found that fat tissue can be used as a microwave communication channel. In this article, the effect of thickness inhomogeneities in fat tissues on the performance of in-body microwave communication at 2.45 GHz is investigated using phantom models. We considered two models namely concave and convex geometrical fat distribution to account for the thickness inhomogeneities. The thickness of the fat tissue is varied from 5 mm to 45 mm and the Gap between the transmitter/receiver and the starting and ending of concavity/convexity is varied from 0 mm to 25 mm for a length of 100 mm to study the behavior in the microwave propagation. The phantoms of different geometries, concave and convex, are used in this work to validate the numerical studies. It was noticed that the convex model exhibited higher signal coupling by an amount of 1 dB (simulation) and 2 dB (measurement) compared to the concave model. From the study, it was observed that the signal transmission improves up to 30 mm thick fat and reaches a plateau when the thickness is increased further.
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| 9. |
- Asan, Noor Badariah, 1984-, et al.
(författare)
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Effects of Blood Vessels on Fat Channel Microwave Communication
- 2018
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Ingår i: 2018 IEEE Conference on Antenna Measurements & Applications (CAMA). - : IEEE. - 9781538657959
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Konferensbidrag (refereegranskat)abstract
- This study aims to investigate the reliability of intra-body microwave propagation through the fat tissue in presence of blood vessels. Here, we consider three types of blood vessels with different sizes. We investigate the impact of the number of blood vessels and their alignment on the transmission of microwave signals through the fat channel. In our study, we employ two probes that act as a transmitter and a receiver. The probes are designed to operate at the Industrial, Scientific, and Medical radio band (2.45 GHz). For a channel length of 100 mm, our results indicate that the presence of the blood vessels may increase the channel path loss by similar to 1.5 dB and similar to 4.5 dB when the vessels are aligned and orthogonally aligned with the fat channel, respectively.
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| 10. |
- Asan, Noor Badariah, 1984-, et al.
(författare)
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Human Fat Tissue : A Microwave Communication Channel
- 2017
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Ingår i: 2017 First IEEE MTT-S International Microwave Bio Conference (IMBIOC). - : IEEE. - 9781538617137
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Konferensbidrag (refereegranskat)abstract
- In this paper, we present an approach for communication through human body tissue in the R-band frequency range. This study examines the ranges of microwave frequencies suitable for intra-body communication. The human body tissues are characterized with respect to their transmission properties using simulation modeling and phantom measurements. The variations in signal coupling with respect to different tissue thicknesses are studied. The simulation and phantom measurement results show that electromagnetic communication in the fat layer is viable with attenuation of approximately 2 dB per 20 mm.
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