Light airplane crash tests at three roll angles

Three similar twin engine general aviation airplanes were crash tested at the Langley impact dynamics research facility at 27 m/sec and at nominal roll angles of 0 deg, -15 deg, and -30 deg. Other flight parameters were held constant. The test facility, instrumentation, test specimens, and test method are briefly described. Structural damage and accelerometer data for each of the three impact conditions are presented and discussed

Light airplane crash tests at three flight-path angles

Three similar twin engine general aviation airplane specimens were crash tested at Langley impact dynamics research facility at 27 m/sec and at flight-path angles of -15 deg, -30 deg, and -45 deg. Other flight parameters were held constant. The test facility, instrumentation, test specimens, and test method are briefly described. Structural damage and accelerometer data for each of the three impact conditions are presented and discussed

Crash tests of three identical low-wing single-engine airplane

Three identical four place, low wing single engine airplane specimens with nominal masses of 1043 kg were crash tested under controlled free flight conditions. The tests were conducted at the same nominal velocity of 25 m/sec along the flight path. Two airplanes were crashed on a concrete surface (at 10 and 30 deg pitch angles), and one was crashed on soil (at a -30 deg pitch angle). The three tests revealed that the specimen in the -30 deg test on soil sustained massive structural damage in the engine compartment and fire wall. Also, the highest longitudinal cabin floor accelerations occurred in this test. Severe damage, but of lesser magnitude, occurred in the -30 deg test on concrete. The highest normal cabin floor accelerations occurred in this test. The least structural damage and lowest accelerations occurred in the 10 deg test on concrete

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

Microwave mobilities of holes in p-type geranium

Hall mobilities of an n-type (GN l) and a p-type (GP 2) germanium single crystal were measured at a microwave frequency of 9 Gc/ sec from 80 °K to 300 °K. A bimodal rectangular cavity designed by Nishina was used in the present investigation. The microwave circuit was nearly the same as that described by Nishina except that the microwave signal was modulated by 1000 cycle per second square-wave signal. The microwave mobilities measured (with sample size correction factor of 0. 423 for n-type and 0. 687 for p-type germanium) were compared with the corresponding d. c. Hall mobilities. For n-type germanium, the discrepancy between the d. c. and microwave mobilities was believed to be predominatly due to the E: -1/2 dependence of the relaxation time (acoustical mode scattering). For p-type germanium, a large deviation occurred at low temperatures and was in agreement with the results obtained by Hambleton et al. and by Watanabe. This result might be explained qualitatively as a combined effect of lattice and impurity scattering, particularly the effect of impurity scattering on the light mass holes

A Paradox of State-Dependent Diffusion and How to Resolve It

Consider a particle diffusing in a confined volume which is divided into two equal regions. In one region the diffusion coefficient is twice the value of the diffusion coefficient in the other region. Will the particle spend equal proportions of time in the two regions in the long term? Statistical mechanics would suggest yes, since the number of accessible states in each region is presumably the same. However, another line of reasoning suggests that the particle should spend less time in the region with faster diffusion, since it will exit that region more quickly. We demonstrate with a simple microscopic model system that both predictions are consistent with the information given. Thus, specifying the diffusion rate as a function of position is not enough to characterize the behaviour of a system, even assuming the absence of external forces. We propose an alternative framework for modelling diffusive dynamics in which both the diffusion rate and equilibrium probability density for the position of the particle are specified by the modeller. We introduce a numerical method for simulating dynamics in our framework that samples from the equilibrium probability density exactly and is suitable for discontinuous diffusion coefficients.Comment: 21 pages, 6 figures. Second round of revisions. This is the version that will appear in Proc Roy So

Non-intrusive and structure preserving multiscale integration of stiff ODEs, SDEs and Hamiltonian systems with hidden slow dynamics via flow averaging

We introduce a new class of integrators for stiff ODEs as well as SDEs. These integrators are (i) {\it Multiscale}: they are based on flow averaging and so do not fully resolve the fast variables and have a computational cost determined by slow variables (ii) {\it Versatile}: the method is based on averaging the flows of the given dynamical system (which may have hidden slow and fast processes) instead of averaging the instantaneous drift of assumed separated slow and fast processes. This bypasses the need for identifying explicitly (or numerically) the slow or fast variables (iii) {\it Nonintrusive}: A pre-existing numerical scheme resolving the microscopic time scale can be used as a black box and easily turned into one of the integrators in this paper by turning the large coefficients on over a microscopic timescale and off during a mesoscopic timescale (iv) {\it Convergent over two scales}: strongly over slow processes and in the sense of measures over fast ones. We introduce the related notion of two-scale flow convergence and analyze the convergence of these integrators under the induced topology (v) {\it Structure preserving}: for stiff Hamiltonian systems (possibly on manifolds), they can be made to be symplectic, time-reversible, and symmetry preserving (symmetries are group actions that leave the system invariant) in all variables. They are explicit and applicable to arbitrary stiff potentials (that need not be quadratic). Their application to the Fermi-Pasta-Ulam problems shows accuracy and stability over four orders of magnitude of time scales. For stiff Langevin equations, they are symmetry preserving, time-reversible and Boltzmann-Gibbs reversible, quasi-symplectic on all variables and conformally symplectic with isotropic friction.Comment: 69 pages, 21 figure

A Method for a Fast Evaluation of the Biostimulant Potential of Different Natural Extracts for Promoting Growth or Tolerance against Abiotic Stress

[EN] Under adverse environmental conditions, biostimulants can help crops withstand abiotic stress while increasing productivity. We have designed a sequential system based on two different biological model organisms¿the baker¿s yeast Saccharomyces cerevisiae and the plant Arabidopsis thaliana¿to evaluate the potential as biostimulants of a battery of 11 different natural extracts on a blind-test basis. Firstly, yeast assays consist in a drop test in solid medium, and a BioScreen® test with liquid cultures. The method is completed with two plant assays to assess effects on germination and growth. The designed method provided relevant data on the ability of each extract to promote biomass accumulation under normal conditions and in the presence of abiotic stresses, such as drought, salinity, or cold. Besides, this laboratory-based method allowed to assess the potential toxicity or unsuspected deleterious effect of each extract in a short period of time (six months) with low budget and space requirements. We could also test the effects of the biostimulants during germination, vegetative, and reproductive growth, under normal and stressed conditions. As each product is tested on different organisms at different developmental stages, we could get some preliminary information on the mode of action. This method enables a fast screen of many different products, in order to select potential candidates to be marketed as biostimulants, avoiding long and expensive field tests with previously uncharacterized productsThis study is a part of the research agreement: Estudio de estimulación del crecimiento y protector frente al estrés abiótico de diferentes formulaciones en levadura, Arabidopsis y tomate funded by Agrométodos SA.Saporta Bon, R.; Bou, C.; Frías, V.; Mulet, JM. (2019). A Method for a Fast Evaluation of the Biostimulant Potential of Different Natural Extracts for Promoting Growth or Tolerance against Abiotic Stress. Agronomy. 9(3):1-16. https://doi.org/10.3390/agronomy9030143S1169

INFLUENCE OF THE ADDITION OF 0.5 AND 1% IN WEIGHT OF MULTI-WALL CARBON NANOTUBES (MWCNTs) IN POLY-LACTIC ACID (PLA) FOR 3D PRINTING

[EN] This research paper presents the characterization of a nanocomposite of polylactic acid (PLA) and carbon nanotubes (MWCNTs) with different percentages of mixture in weight. This thermal characterization determines the influence carbon nanotubes have when those are added into PLA. This last one been used for additive manufacturing (FFF technology).. Once finished the tests, it was observed that the nanocomposite PLA/MWCNTs have a positive application during 3D printing. The extrusion temperatures used in tests were between 177 and 185ºC. The parameters given for the SLISER software, obtained a promising result for the application of a PLA / MWCNT nanocomposite into 3D printing.Cobos, C.; Conejero Rodilla, A.; Fenollar, O.; Ferrándiz Bou, S. (2019). INFLUENCE OF THE ADDITION OF 0.5 AND 1% IN WEIGHT OF MULTI-WALL CARBON NANOTUBES (MWCNTs) IN POLY-LACTIC ACID (PLA) FOR 3D PRINTING. Procedia Manufacturing. 41:875-881. https://doi.org/10.1016/j.promfg.2019.10.010S8758814