2,697 research outputs found
Joint Ultra-wideband and Signal Strength-based Through-building Tracking for Tactical Operations
Accurate device free localization (DFL) based on received signal strength
(RSS) measurements requires placement of radio transceivers on all sides of the
target area. Accuracy degrades dramatically if sensors do not surround the
area. However, law enforcement officers sometimes face situations where it is
not possible or practical to place sensors on all sides of the target room or
building. For example, for an armed subject barricaded in a motel room, police
may be able to place sensors in adjacent rooms, but not in front of the room,
where the subject would see them. In this paper, we show that using two
ultra-wideband (UWB) impulse radios, in addition to multiple RSS sensors,
improves the localization accuracy, particularly on the axis where no sensors
are placed (which we call the x-axis). We introduce three methods for combining
the RSS and UWB data. By using UWB radios together with RSS sensors, it is
still possible to localize a person through walls even when the devices are
placed only on two sides of the target area. Including the data from the UWB
radios can reduce the localization area of uncertainty by more than 60%.Comment: 9 pages, conference submissio
Dial It In: Rotating RF Sensors to Enhance Radio Tomography
A radio tomographic imaging (RTI) system uses the received signal strength
(RSS) measured by RF sensors in a static wireless network to localize people in
the deployment area, without having them to carry or wear an electronic device.
This paper addresses the fact that small-scale changes in the position and
orientation of the antenna of each RF sensor can dramatically affect imaging
and localization performance of an RTI system. However, the best placement for
a sensor is unknown at the time of deployment. Improving performance in a
deployed RTI system requires the deployer to iteratively "guess-and-retest",
i.e., pick a sensor to move and then re-run a calibration experiment to
determine if the localization performance had improved or degraded. We present
an RTI system of servo-nodes, RF sensors equipped with servo motors which
autonomously "dial it in", i.e., change position and orientation to optimize
the RSS on links of the network. By doing so, the localization accuracy of the
RTI system is quickly improved, without requiring any calibration experiment
from the deployer. Experiments conducted in three indoor environments
demonstrate that the servo-nodes system reduces localization error on average
by 32% compared to a standard RTI system composed of static RF sensors.Comment: 9 page
Study and Implementation of Compact Modeling Techniques for the Energy Analysis and Optimization of Complex Systems
L'abstract è presente nell'allegato / the abstract is in the attachmen
Breathfinding: A Wireless Network that Monitors and Locates Breathing in a Home
This paper explores using RSS measurements on many links in a wireless
network to estimate the breathing rate of a person, and the location where the
breathing is occurring, in a home, while the person is sitting, laying down,
standing, or sleeping. The main challenge in breathing rate estimation is that
"motion interference", i.e., movements other than a person's breathing,
generally cause larger changes in RSS than inhalation and exhalation. We
develop a method to estimate breathing rate despite motion interference, and
demonstrate its performance during multiple short (3-7 minute) tests and during
a longer 66 minute test. Further, for the same experiments, we show the
location of the breathing person can be estimated, to within about 2 m average
error in a 56 square meter apartment. Being able to locate a breathing person
who is not otherwise moving, without calibration, is important for applications
in search and rescue, health care, and security
Izquierdas, populismos y nacionalismos: una relación difÃcil entre ideologÃas diferentes (y en ocasiones contradictorias). (Sobre Latinoamérica, ahora o nunca, de Juan Domingo Perón)
A method to empirically set the coefficients of an analytical model of battery aging
The increase of battery-powered devices and systems, from consumer electronics to electric vehicles, means that the reliability analysis of such systems concerns both energy cells and battery packs, as well as circuitry. For this reason, battery modeling has been one of most developed research areas during the last two decades. In this context, the Millner model, which is based on crack propagation theory, provides an accurate mathematical model for the analysis of the degradation (i.e., aging or capacity fading) of lithium-ion cells. In order to extend the application of the Millner model in a practical and simplified way, this work describes a method to empirically set the coefficients of this model by extracting these values from experimental data only published by the manufacturer and some researchers. When simulating an AMP20m1HD-A prismatic pouch cell at different working and operating conditions, the results show an accurate analysis of the capacity fading, with an error of generally less than 3%
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