429,902 research outputs found
The Highly Miniaturised Radiation Monitor
We present the design and preliminary calibration results of a novel highly
miniaturised particle radiation monitor (HMRM) for spacecraft use. The HMRM
device comprises a telescopic configuration of active pixel sensors enclosed in
a titanium shield, with an estimated total mass of 52 g and volume of 15
cm. The monitor is intended to provide real-time dosimetry and
identification of energetic charged particles in fluxes of up to 10
cm s (omnidirectional). Achieving this capability with such a
small instrument could open new prospects for radiation detection in space.Comment: 17 pages, 15 figure
Miniature biplanar coils for alkali-metal-vapor magnetometry
Atomic spin sensors offer precision measurements using compact,
microfabricated packages, placing them in a competitive position for both
market and research applications. Performance of these sensors such as dynamic
range may be enhanced through magnetic field control. In this work, we discuss
the design of miniature coils for three-dimensional, localized field control by
direct placement around the sensor, as a flexible and compact alternative to
global approaches used previously. Coils are designed on biplanar surfaces
using a stream-function approach and then fabricated using standard
printed-circuit techniques. Application to a laboratory-scale optically pumped
magnetometer of sensitivity 20 fT/Hz is shown. We also
demonstrate the performance of a coil set measuring
mm that is optimized specifically for magnetoencephalography, where
multiple sensors are operated in proximity to one another. Characterization of
the field profile using Rb free-induction spectroscopy and other
techniques show 96% field homogeneity over the target volume of a MEMS vapor
cell and a compact stray field contour of 1% at 20 mm from the center of
the cell
GeoNEX: A Cloud Gateway for Near Real-time Processing of Geostationary Satellite Products
The emergence of a new generation of geostationary satellite sensors provides land andatmosphere monitoring capabilities similar to MODIS and VIIRS with far greater temporal resolution (5-15 minutes). However, processing such large volume, highly dynamic datasets requires computing capabilities that (1) better support data access and knowledge discovery for scientists; (2) provide resources to enable real-time processing for emergency response (wildfire, smoke, dust, etc.); and (3) provide reliable and scalable services for the broader user community. This paper presents an implementation of GeoNEX (Geostationary NASA-NOAA Earth Exchange) services that integrate scientific algorithms with Amazon Web Services (AWS) to provide near realtime monitoring (~5 minute latency) capability in a hybrid cloud-computing environment. It offers a user-friendly, manageable and extendable interface and benefits from the scalability provided by Amazon Web Services. Four use cases are presented to illustrate how to (1) search and access geostationary data; (2) configure computing infrastructure to enable near real-time processing; (3) disseminate and utilize research results, visualizations, and animations to concurrent users; and (4) use a Jupyter Notebook-like interface for data exploration and rapid prototyping. As an example of (3), the Wildfire Automated Biomass Burning Algorithm (WF_ABBA) was implemented on GOES-16 and -17 data to produce an active fire map every 5 minutes over the conterminous US. Details of the implementation strategies, architectures, and challenges of the use cases are discussed
Determination of the 3D Human Spine Posture from Wearable Inertial Sensors and a Multibody Model of the Spine
[Abstract] Determination of spine posture is of great interest for the effective prevention, evaluation, treatment and evolution monitoring of spinal disorders. Limitations of traditional imaging systems, including cost, radiation exposure (for X-ray based systems), projection volume issues and subject positioning requirements, etc., make non-invasive motion assessment tools effective alternatives for clinical and non-clinical use. In this work, a procedure was developed to obtain a subject-specific multibody model of the spine using either inertial or optical sensors and, based on this multibody model, to estimate the locations and orientations of the 17 vertebrae constituting the thoracolumbar spine. The number and calibration of the sensors, angular offsets, scaling difficulties and gender differences were addressed to achieve an accurate 3D-representation of the spine. The approach was validated by comparing the estimated positions of the sensors on 14 healthy subjects with those provided by an optical motion capture system. A mean position error of lower than 12 mm was obtained, thus showing that the proposed method can offer an effective non-invasive tool for the assessment of spine posture.This work was funded by the Spanish MCI under project PGC2018-095145-B-I00, co-financed by the EU through the EFRD program, and by the Galician Government under grant ED431C2019/29 and under grant IN853B-2018/02Xunta de Galicia; ED431C2019/29Xunta de Galicia; IN853B-2018/0
Target Mass Monitoring and Instrumentation in the Daya Bay Antineutrino Detectors
The Daya Bay experiment measures sin^2 2{\theta}_13 using functionally
identical antineutrino detectors located at distances of 300 to 2000 meters
from the Daya Bay nuclear power complex. Each detector consists of three nested
fluid volumes surrounded by photomultiplier tubes. These volumes are coupled to
overflow tanks on top of the detector to allow for thermal expansion of the
liquid. Antineutrinos are detected through the inverse beta decay reaction on
the proton-rich scintillator target. A precise and continuous measurement of
the detector's central target mass is achieved by monitoring the the fluid
level in the overflow tanks with cameras and ultrasonic and capacitive sensors.
In addition, the monitoring system records detector temperature and levelness
at multiple positions. This monitoring information allows the precise
determination of the detectors' effective number of target protons during data
taking. We present the design, calibration, installation and in-situ tests of
the Daya Bay real-time antineutrino detector monitoring sensors and readout
electronics.Comment: 22 pages, 20 figures; accepted by JINST. Changes in v2: minor
revisions to incorporate editorial feedback from JINS
Experimental Study of Various Techniques to Protect Ice-Rich Cut Slopes
INE/AUTC 15.08 and INE/AUTC 13.07 (2013) Construction Repor
Respiration rate and volume measurements using wearable strain sensors.
Current methods for continuous respiration monitoring such as respiratory inductive or optoelectronic plethysmography are limited to clinical or research settings; most wearable systems reported only measures respiration rate. Here we introduce a wearable sensor capable of simultaneously measuring both respiration rate and volume with high fidelity. Our disposable respiration sensor with a Band-Aid© like formfactor can measure both respiration rate and volume by simply measuring the local strain of the ribcage and abdomen during breathing. We demonstrate that both metrics are highly correlated to measurements from a medical grade continuous spirometer on participants at rest. Additionally, we also show that the system is capable of detecting respiration under various ambulatory conditions. Because these low-powered piezo-resistive sensors can be integrated with wireless Bluetooth units, they can be useful in monitoring patients with chronic respiratory diseases in everyday settings
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