Daniel Sexton

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– IEEE 802.15.4 shares its frequency band with many existing technologies such as Bluetooth, IEEE 802.11, microwave ovens and other devices that use the same ISM bandwidth. The interference caused by these technologies can degrade the performance of an IEEE 802.15.4 based wireless network. In this paper we study such degrading effects on a network installed(More)
–Wireless Mesh Sensor Networks are being deployed today in various monitoring and control applications. Some radio network designs, such as ZigBee, presume that radio connectivity is reasonably consistent over time. Others take the opposite approach of presuming that links are entirely unreliable, and build large degrees of physical redundancy into the(More)
In collaboration under a Department of Energy grant for the Industries of the Future, General Electric and Sensicast Systems have studied performance of 2.4 GHz IEEE 802.15.4 radio transceivers in factory environments, with particular attention to jamming from 802.11 and multipath fading. Temporal and frequency variations in link quality are explored. The(More)
This paper explores the properties of short-range broadband wireless communications for underwater operations using electric conduction. Electric field in the water is generated by a pair of electrodes with opposite current and detected by two receiving electrodes. Ranges of operation can be shorter than 1 m, suitable for contactless data collection by(More)
A model for piezoelectric vibration energy harvesting with a piezoelectric cantilever beam is presented. The model incorporates expressions for variable geometry, tip mass, and material constants, and allows the parameterized determination of the voltage and power produced over a purely resistive load. The model is of a lumped-element form, with the base(More)
BACKGROUND Subdural grid (SDG) electrodes have been the gold standard of invasive monitoring in medically refractory epilepsy; however, in some centers, application of SDGs has been reduced by the progressive application of stereoelectroencephalography (SEEG). This study reviews the efficacy of SDG electrode monitoring after the incorporation of the SEEG(More)
Wireless underwater transmission is considered using electric field generated by a pair of electrodes with opposite current and detected by two receiving electrodes. Experiments were conducted at frequencies between 100 kHz and 6.35 MHz, using orthogonal frequency division multiplexing (OFDM). Our lab tests were performed in a plastic tank filled with salt(More)
In our previous research in underwater electromagnetic communications, we showed that magnitude variation with frequency, and time-invariance of the channel, motivated the design of an orthogonal frequency division multiplexing (OFDM) system with unequal bit loading, which is the subject of our current research in simulation and experiment. We have also(More)
The utilization of high accuracy sensors in harsh environments has been limited by the temperature constraints of the control electronics that must be co-located with the sensor. Several methods of remote interrogation for resonant sensors are presented in this paper which would allow these sensors to be extended to harsh environments. This work in(More)
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