346 research outputs found
Development of an energy-absorbing passenger seat for a transport aircraft
Commercial air transport passenger safety and survivability, in the event of an impact-survivable crash, are subjects receiving increased technical focus/study by the aviation community. A B-720 aircraft, highly instrumented, and remotely controlled from the ground by a pilot in a simulated cockpit, was crashed on a specially prepared gravel covered impact site. The aircraft was impacted under controlled conditions in an air-to-ground gear-up mode, at a nominal speed of 150 knots and 4-1/2 deg glide slope. Data from a number of on board, crash worthiness experiments provided valuable information related to structural loads/failure modes, antimisting kerosene fuel, passenger and attendant restraint systems and energy absorbing seats. The development of an energy absorbing (EA) seat accomplished through innovative modification of a typical modern standard commercial aviation transport, three passenger seat is described
White Papers: Drilling Active Tectonics and Magmatism (Volcanics, Geoprisms, and Fault Zones Post-SAFOD)
Aplicação do Mixolab na avaliação da qualidade reológica de farinhas refinadas e integrais de trigo
Germinação e vigor de sementes de trigo inoculadas com Azospirillum brasilense.
Editores técnicos: Joseani Mesquita Antunes, Ana Lídia Variani Bonato, Márcia Barrocas Moreira Pimentel
Search for anions in molecular sources: C4H- detection in L1527
We present the results of a search for the negative ion C4H- in various dark
clouds, low mass star-forming regions and photon-dominated regions (PDRs). We
have also searched for C6H-, C2H- and CN- in some of the sources. The
millimeter-wave observations were carried out with the IRAM-30m telescope. We
detect C4H-, through the J = 9-8 and J = 10-9 rotational transitions, in the
low mass star-forming region L1527. We thus confirm the tentative detection of
the J = 9-8 line recently reported toward this source. The [C4H-]/[C4H] ratio
found is 0.011 %, which is slightly lower than the value observed in IRC
+10216, 0.024 %, but above the 3 sigma upper limit we derive in TMC-1, < 0.0052
%. We have also derived an upper limit for the [C6H-]/[C6H] ratio in the
Horsehead Nebula, and for various anion-to-neutral ratios in the observed
sources. These results are compared with recent chemical models.Comment: 4 pages, 1 figure; accepted for A&A Letter
Astronomical identification of CN-, the smallest observed molecular anion
We present the first astronomical detection of a diatomic negative ion, the
cyanide anion CN-, as well as quantum mechanical calculations of the excitation
of this anion through collisions with para-H2. CN- is identified through the
observation of the J = 2-1 and J = 3-2 rotational transitions in the C-star
envelope IRC +10216 with the IRAM 30-m telescope. The U-shaped line profiles
indicate that CN-, like the large anion C6H-, is formed in the outer regions of
the envelope. Chemical and excitation model calculations suggest that this
species forms from the reaction of large carbon anions with N atoms, rather
than from the radiative attachment of an electron to CN, as is the case for
large molecular anions. The unexpectedly large abundance derived for CN-, 0.25
% relative to CN, makes likely its detection in other astronomical sources. A
parallel search for the small anion C2H- remains so far unconclusive, despite
the previous tentative identification of the J = 1-0 rotational transition. The
abundance of C2H- in IRC +10216 is found to be vanishingly small, < 0.0014 %
relative to C2H.Comment: 5 pages, 4 figures; accepted for publication in A&A Letter
Wavelet analysis applied on temporal data sets in order to reveal possible pre-seismic radio anomalies and comparison with the trend of the raw data
Since 2009, several radio receivers have been installed throughout Europe in order to realize the INFREP European radio network for studying the VLF (10-50 kHz) and LF (150-300 kHz) radio precursors of earthquakes. Precursors can be related to “anomalies” in the night-time behavior of VLF signals. A suitable method of analysis is the use of the Wavelet spectra. Using the “Morlet function”, the Wavelet transform of a time signal is a complex series that can be usefully represented by its square amplitude, i.e. considering the so-called Wavelet power spectrum.
The power spectrum is a 2D diagram that, once properly normalized with respect to the power of the white noise, gives information on the strength and precise time of occurrence of the various Fourier components, which are present in the original time series. The main difference between the Wavelet power spectra and the Fourier power spectra for the time series is that the former identifies the frequency content along the operational time, which cannot be done with the latter. Anomalies are identified as regions of the Wavelet spectrogram characterized by a sudden increase in the power strength.
On January 30, 2020 an earthquake with Mw= 6.0 occurred in Dodecanese Islands. The results of the Wavelet analysis carried out on data collected some INFREP receivers is compared with the trends of the raw data. The time series from January 24, 2020 till January 31, 2000 was analyzed. The Wavelet spectrogram shows a peak corresponding to a period of 1 day on the days before January 30. This anomaly was found for signals transmitted at the frequencies 19,58 kHz, 20, 27 kHz, 23,40 kHz with an energy in the peak increasing from 19,58 kHz to 23,40 kHz. In particular, the
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signal at the frequency 19,58 kHz, shows a peak on January 29, while the frequencies 20,27 kHz and 23,40 kHz are characterized by a peak starting on January 28 and continuing to January 29. The results presented in this work shows the perspective use of the Wavelet spectrum analysis as an operational tool for the detection of anomalies in VLF and LF signal potentially related to EQ precursors
Produção de semente genética de soja na Embrapa Trigo em 2016/2017.
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