2,675 research outputs found

    Wildland Fire Location Management System (WFLMS)

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    Wildland firefighters work in complex, dangerous environments where effective communication is key to developing situational awareness. Currently, the only communication firefighters have is with Very High Frequency (VHF) 160 MHz band analog radios. While digital radio protocols could potentially allow location data and commands to be sent to field crews, the technology is primarily for voice communication. This project presents a new system that frees up voice channels and uses LoRa transceivers for robust communication. The system allows for emergency and location reports to be sent to a dispatcher via an airborne repeater. The entire system is software-defined, so it can be updated as firefighter needs evolve

    Impact of concurrent pregnancy and lactation on maternal nestbuilding, estradiol and progesterone concentrations in rabbits

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    [EN] We evaluated the impact of concurrent pregnancy and lactation on: nest-building (i.e., digging, straw-carrying, hair-pulling), food intake, milk output, body weight, and the concentration of estradiol and progesterone in blood. Digging was lower in pregnant-lactating (PL) rabbits, compared with pregnant-only (PO) does, on 21-23 d (52±64 vs. 104±86 g, respectively; mean±SD; P<0.05). Straw-carrying was also reduced in PL does on 24-26 d (9±27 vs. 79±94 g; P<0.005), 27-29 (27±56 vs. 99±77 g; P<0.005), and in the total amount of material introduced into the nest box (132±167 vs. 286±217 g; P<0.02). Hair-pulling was expressed by practically all animals. Food intake declined in PO does on the three days preceding parturition (P<0.01) and increased markedly during lactation; this increase was much larger in PL than in lactating-only (LO) rabbits (P<0.01). Milk output was similar between PL and LO does during the first 21 d of lactation but a marked decline in this parameter occurred in PL does from then until 30 d. The differences in nest-building between PL and PO rabbits may be related to the concentrations of estradiol and progesterone on specific days of pregnancy. PL does showed significantly higher estradiol levels than PO animals on pregnancy 1 d (33±13 vs. 23±4 pg/mL; P<0.02) and 21 (34±19 vs. 24±6 pg/mL; P<0.05) and also higher levels of progesterone on pregnancy 1 d (4±5 vs. 1±2 ng/mL; P<0.05). However, PL rabbits had lower levels of progesterone on 7 d (6±3 vs. 9±2 ng/mL; P<0.02) and 14 d (8±3 vs. 11±3 ng/mL; P<0.005) than PO does. Our results indicate that the unique endocrine milieu of PL rabbits has a direct bearing on specific behavioral and physiological phenomena that impact productivity on the farm.González-Mariscal, G.; Gallegos, J.; Sierra-Ramírez, A.; Garza Flores, J. (2009). Impact of concurrent pregnancy and lactation on maternal nestbuilding, estradiol and progesterone concentrations in rabbits. World Rabbit Science. 17(3):145-152. doi:10.4995/wrs.2009.65414515217

    Colliding Pulse Mode-Locked Laser Diode using Multimode Interference Reflectors

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    We present a novel fully monolithic Colliding Pulse Mode-Locked Laser Diode (CPML) using Multimode Interference Reflectors (MMIRs) to create the laser resonator. We demonstrate experimentally for the first time to our knowledge the Colliding Pulse mode-locking of a laser using MMIRs by observation of the Optical Spectrum and by measuring the frequency spacing between the modes. This component is a promising candidate for Stable Millimeter-Wave Generation in ultra-wideband wireless communication links. Multimode Interference Reflectors are very versatile components that allow avoiding the required cleaved facets to operate

    Measurement of 1323 and 1487 keV resonances in 15N({\alpha}, {\gamma})19F with the recoil separator ERNA

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    The origin of fluorine is a widely debated issue. Nevertheless, the ^{15}N({\alpha},{\gamma})^{19}F reaction is a common feature among the various production channels so far proposed. Its reaction rate at relevant temperatures is determined by a number of narrow resonances together with the DC component and the tails of the two broad resonances at E_{c.m.} = 1323 and 1487 keV. Measurement through the direct detection of the 19F recoil ions with the European Recoil separator for Nuclear Astrophysics (ERNA) were performed. The reaction was initiated by a 15N beam impinging onto a 4He windowless gas target. The observed yield of the resonances at Ec.m. = 1323 and 1487 keV is used to determine their widths in the {\alpha} and {\gamma} channels. We show that a direct measurement of the cross section of the ^{15}N({\alpha},{\gamma})^{19}F reaction can be successfully obtained with the Recoil Separator ERNA, and the widths {\Gamma}_{\gamma} and {\Gamma}_{\alpha} of the two broad resonances have been determined. While a fair agreement is found with earlier determination of the widths of the 1487 keV resonance, a significant difference is found for the 1323 keV resonance {\Gamma}_{\alpha} . The revision of the widths of the two more relevant broad resonances in the 15N({\alpha},{\gamma})19F reaction presented in this work is the first step toward a more firm determination of the reaction rate. At present, the residual uncertainty at the temperatures of the ^{19}F stellar nucleosynthesis is dominated by the uncertainties affecting the Direct Capture component and the 364 keV narrow resonance, both so far investigated only through indirect experiments.Comment: 8 pages, 11 figures. Accepted for publication in PR

    Transient Thermal Analysis of a Railroad Bearing Adapter for Optimal Placement of Onboard Sensors

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    Bearing temperature serves as an important metric used in identifying defective bearings in the rail industry. Current defect detection systems, such as the Hot Box Detectors (HBDs), are used to measure the temperature of freight car roller bearings. The HBD is a wayside device that utilizes a non-contact infrared sensor to determine the operating temperature of a railroad bearing as it passes over the HBD. Railroads analyze the data collected by HBDs to detect and flag defective bearings. If the operating temperature of a bearing surpasses a predetermined threshold, an emergency stop is initiated, and the bearing is removed from service and sent for inspection. One major drawback of HBDs is that they have been associated with many “false positives,” which has resulted in costly train stoppages and delays. To combat that, researchers have opted to use wireless onboard sensor devices mounted directly on the bearing adapter. One such device is the wireless onboard health monitoring system developed by the University Transportation Center for Railway Safety (UTCRS) that utilizes temperature and vibration sensors to detect the condition of rolling stock. However, because the device is affixed to the bearing adapter and not the bearing itself, the strategic placement of the temperature sensor on the adapter is crucial in minimizing the thermal lag associated with the heat transfer from the bearing to the location where the temperature is measured, as this will directly affect the accuracy of the readings. By conducting a transient heat transfer finite element analysis (FEA), the estimated time-lag and the temperature distribution within the bearing adapter can be determined. To validate the accuracy of the transient FEA model, the results were compared to data acquired from laboratory testing performed on the UTCRS dynamic bearing test rigs. The results obtained in this study can be used to identify optimal anchor points for the temperature sensors on the bearing adapter, and in turn, increase the proficiency of wireless onboard sensor devices in detecting defective components
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