1,616 research outputs found
Fiber optic microphone having a pressure sensing reflective membrane and a voltage source for calibration purpose
A fiber optic microphone is provided for measuring fluctuating pressures. An optical fiber probe having at least one transmitting fiber for transmitting light to a pressure-sensing membrane and at least one receiving fiber for receiving light reflected from a stretched membrane is provided. The pressure-sensing membrane may be stretched for high frequency response. Further, a reflecting surface of the pressure-sensing membrane may have dimensions which substantially correspond to dimensions of a cross section of the optical fiber probe. Further, the fiber optic microphone can be made of materials for use in high temperature environments, for example greater than 1000 F. A fiber optic probe is also provided with a back plate for damping membrane motion. The back plate further provides a means for on-line calibration of the microphone
High temperature fiber optic microphone having a pressure-sensing reflective membrane under tensile stress
A fiber optic microphone is provided for measuring fluctuating pressures. An optical fiber probe having at least one transmitting fiber for transmitting light to a pressure-sensing membrane and at least one receiving fiber for receiving light reflected from a stretched membrane is provided. The pressure-sensing membrane may be stretched for high frequency response. Further, a reflecting surface of the pressure-sensing membrane may have dimensions which substantially correspond to dimensions of a cross section of the optical fiber probe. Further, the fiber optic microphone can be made of materials for use in high temperature environments, for example greater than 1000 F. A fiber optic probe is also provided with a backplate for damping membrane motion. The backplate further provides a means for on-line calibration of the microphone
Exploratory approach for network behavior clustering in LoRaWAN
The interest in the Internet of Things (IoT) is increasing both as for research and market perspectives. Worldwide, we are witnessing the deployment of several IoT networks for different applications, spanning from home automation to smart cities. The majority of these IoT deployments were quickly set up with the aim of providing connectivity without deeply engineering the infrastructure to optimize the network efficiency and scalability. The interest is now moving towards the analysis of the behavior of such systems in order to characterize and improve their functionality. In these IoT systems, many data related to device and human interactions are stored in databases, as well as IoT information related to the network level (wireless or wired) is gathered by the network operators. In this paper, we provide a systematic approach to process network data gathered from a wide area IoT wireless platform based on LoRaWAN (Long Range Wide Area Network). Our study can be used for profiling IoT devices, in order to group them according to their characteristics, as well as detecting network anomalies. Specifically, we use the k-means algorithm to group LoRaWAN packets according to their radio and network behavior. We tested our approach on a real LoRaWAN network where the entire captured traffic is stored in a proprietary database. Quite important is the fact that LoRaWAN captures, via the wireless interface, packets of multiple operators. Indeed our analysis was performed on 997, 183 packets with 2169 devices involved and only a subset of them were known by the considered operator, meaning that an operator cannot control the whole behavior of the system but on the contrary has to observe it. We were able to analyze clusters’ contents, revealing results both in line with the current network behavior and alerts on malfunctioning devices, remarking the reliability of the proposed approach
Relations among structural parameters in barred galaxies with a direct measurement of bar pattern speed
We investigate the relations between the properties of bars and their host
galaxies in a sample of 77 nearby barred galaxies, spanning a wide range of
morphological types and luminosities, with 34 SB0-SBa and 43 SBab-SBc galaxies.
The sample includes all the galaxies with reliable direct measurement of their
bar pattern speed based on long-slit or integral-field stellar spectroscopy
using the Tremaine-Weinberg method. We limited our analysis to the galaxies
with a relatively small relative error on the bar pattern speed (smaller than
50 per cent) and not hosting an ultrafast bar. For each galaxy, we collected
the radius, strength, pattern speed, corotation radius, and rotation rate for
the bar and we also collected the Hubble type and absolute SDSS r-band
magnitude. We also used literature bulge-to-total luminosity ratio for a
subsample of 53 galaxies with an available photometric decomposition. We
confirmed earlier observational findings that longer bars rotate with lower bar
pattern speeds, shorter bars are weaker, and bars with a small bar rotation
rate rotate with higher bar pattern speeds and have smaller corotation radii.
In addition, we found that stronger bars rotate with lower bar pattern speeds,
as predicted from the interchange of angular momentum during bar evolution,
which in turn may depend on different galaxy properties. Moreover, we report
that brighter galaxies host longer bars, which rotate with lower bar pattern
speeds and have larger corotation radii. This result is in agreement with a
scenario of downsizing in bar formation, if more massive galaxies formed
earlier and had sufficient time to slow down, grow in length, and push
corotation outwards.Comment: revised and accepted for pubblication in Astronomy & Astrophysic
Farmer-Driven Research for Developing Models of Successful Low Input Dairy Farms of Small to Medium Size in the American Midwest
The dairy industry in the upper Midwest continues to evolve with a drastic reduction in the number of dairy farms with less than 100 cows that utilise tie-stall housing. Many of the farms that do remain are at a critical point where facilities require renovation or replacement that is not economic. Rural communities have fewer residents engaged in agriculture to participate in the local economy and the rural landscape includes many farm sites that are abandoned. Low input dairies are an alternative system developed by farmers as a grass-roots movement. Low input farms may include grazing, outdoor housing throughout the year, crossbreeding, group housing of calves, etc. Barns formerly used to stable cows may be renovated to provide a milking centre. Low input dairy farmers are eager to participate in on-farm research when they determine the direction of research. We will describe one trial designed to answer questions determined by farmers and outline our research approach to designing effective reduced input dairy farms. The objective is to identify the essential components of management and organisation for low input dairy farms in the American Midwest
Numerical tests of the large charge expansion
We perform Monte-Carlo measurements of two and three point functions of
charged operators in the critical O(2) model in 3 dimensions. Our results are
compatible with the predictions of the large charge superfluid effective field
theory. To obtain reliable measurements for large values of the charge, we
improved the Worm algorithm and devised a measurement scheme which mitigates
the uncertainties due to lattice and finite size effects.Comment: 16 pages, 12 figures. v2: Improved finite size scaling. v3: Added
comparison between Monte Carlo update
Comparison of Astrand VO2 Max Prediction to a Graded Leg Ergometry VO2 Max Test in Endurance Athletes
Please refer to the pdf version of the abstract located adjacent to the title
Campus smoking policies and smoking-related Twitter posts originating from California public universities: Retrospective study
BACKGROUND: The number of colleges and universities with smoke- or tobacco-free campus policies has been increasing. The effects of campus smoking policies on overall sentiment, particularly among young adult populations, are more difficult to assess owing to the changing tobacco and e-cigarette product landscape and differential attitudes toward policy implementation and enforcement. OBJECTIVE: The goal of the study was to retrospectively assess the campus climate toward tobacco use by comparing tweets from California universities with and those without smoke- or tobacco-free campus policies. METHODS: Geolocated Twitter posts from 2015 were collected using the Twitter public application programming interface in combination with cloud computing services on Amazon Web Services. Posts were filtered for tobacco products and behavior-related keywords. A total of 42,877,339 posts were collected from 2015, with 2837 originating from a University of California or California State University system campus, and 758 of these manually verified as being about smoking. Chi-square tests were conducted to determine if there were significant differences in tweet user sentiments between campuses that were smoke- or tobacco-free (all University of California campuses and California State University, Fullerton) compared to those that were not. A separate content analysis of tweets included in chi-square tests was conducted to identify major themes by campus smoking policy status. RESULTS: The percentage of positive sentiment tweets toward tobacco use was higher on campuses without a smoke- or tobacco-free campus policy than on campuses with a smoke- or tobacco-free campus policy (76.7% vs 66.4%, P=.03). Higher positive sentiment on campuses without a smoke- or tobacco-free campus policy may have been driven by general comments about one’s own smoking behavior and comments about smoking as a general behavior. Positive sentiment tweets originating from campuses without a smoke- or tobacco-free policy had greater variation in tweet type, which may have also contributed to differences in sentiment among universities. CONCLUSIONS: Our study introduces preliminary data suggesting that campus smoke- and tobacco-free policies are associated with a reduction in positive sentiment toward smoking. However, continued expressions and intentions to smoke and reports of one’s own smoking among Twitter users suggest a need for more research to better understand the dynamics between implementation of smoke- and tobacco-free policies and resulting tobacco behavioral sentiment
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