200 research outputs found

    Analysis of the influence of braking control laws on gear walk

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    The problem of gear walk on landing gear becomes increasingly serious. A rigid-flexible coupling dynamic half-axle main landing gear model, verified to be in accordance with the test data and the original deceleration control system, are built to study the gear walk problems. The co-simulation method is adopted. According to the severe gear walk phenomenon under the deceleration braking system, two modified braking control laws-only the reference speed-speed difference (with PBM) control and the one combining the PBM with the fuzzy control are designed for this type of airplane to weaken the gear walk. The simulating results show that the modified braking control law weakens the gear walk considerably. The braking frequency increases by about 17 %. The average wheel axle gear walk average amplitude decreases by 73 % and the longitudinal acceleration drops by about 91 %. The braking frequency decreases by 50 % so that the vibration frequency of the gear walk decreases by about 59 %. The combined braking control law is verified that is of great stability, adaptability and robustness under variable external conditions

    Diaqua­bis(5-carb­oxy-2-methyl-1H-imidazole-4-carboxyl­ato-κ2 N 3,O 4)manganese(II)

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    The title complex, [Mn(C6H5N2O4)2(H2O)2], was obtained by hydro­thermal synthesis. The MnII atom, which lies on an inversion centre, displays a slightly distorted octa­hedral geometry. In the crystal packing, complex mol­ecules are linked by inter­molecular O—H⋯O and N—H⋯O hydrogen bonds to form a three-dimensional supramolecular structure. The title complex is isostructural with the corresponding cadmium(II) complex [Nie, Wen, Wu, Liu & Liu (2007 ▶). Acta Cryst. E63, m753–m755]

    The LAMOST Complete Spectroscopic Survey of Pointing Area (LaCoSSPAr) in the Southern Galactic Cap I. The Spectroscopic Redshift Catalog

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    We present a spectroscopic redshift catalog from the LAMOST Complete Spectroscopic Survey of Pointing Area (LaCoSSPAr) in the Southern Galactic Cap (SGC), which is designed to observe all sources (Galactic and extra-galactic) by using repeating observations with a limiting magnitude of r=18.1 magr=18.1~mag in two 20 deg220~deg^2 fields. The project is mainly focusing on the completeness of LAMOST ExtraGAlactic Surveys (LEGAS) in the SGC, the deficiencies of source selection methods and the basic performance parameters of LAMOST telescope. In both fields, more than 95% of galaxies have been observed. A post-processing has been applied to LAMOST 1D spectrum to remove the majority of remaining sky background residuals. More than 10,000 spectra have been visually inspected to measure the redshift by using combinations of different emission/absorption features with uncertainty of σz/(1+z)<0.001\sigma_{z}/(1+z)<0.001. In total, there are 1528 redshifts (623 absorption and 905 emission line galaxies) in Field A and 1570 redshifts (569 absorption and 1001 emission line galaxies) in Field B have been measured. The results show that it is possible to derive redshift from low SNR galaxies with our post-processing and visual inspection. Our analysis also indicates that up to 1/4 of the input targets for a typical extra-galactic spectroscopic survey might be unreliable. The multi-wavelength data analysis shows that the majority of mid-infrared-detected absorption (91.3%) and emission line galaxies (93.3%) can be well separated by an empirical criterion of W2−W3=2.4W2-W3=2.4. Meanwhile, a fainter sequence paralleled to the main population of galaxies has been witnessed both in MrM_r/W2−W3W2-W3 and M∗M_*/W2−W3W2-W3 diagrams, which could be the population of luminous dwarf galaxies but contaminated by the edge-on/highly inclined galaxies (∼30%\sim30\%).Comment: 19 pages, 14 figures, 2 MRT, accepted by ApJ

    Complete sequence and organization of Antheraea pernyi nucleopolyhedrovirus, a dr-rich baculovirus

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    <p>Abstract</p> <p>Background</p> <p>The completion and reporting of baculovirus genomes is extremely important as it advances our understanding of gene function and evolution. Due to the large number of viral genomes now sequenced it is very important that authors present significantly detailed analyses to advance the understanding of the viral genomes. However, there is no report of the <it>Antheraea pernyi </it>nucleopolyhedrovirus (AnpeNPV) genome.</p> <p>Results</p> <p>The genome of AnpeNPV, which infects Chinese tussah silkworm (<it>Antheraea pernyi</it>), was sequenced and analyzed. The genome was 126,629 bp in size. The G+C content of the genome, 53.4%, was higher than that of most of the sequenced baculoviruses. 147 open reading frames (ORFs) that putatively encode proteins of 50 or more amino acid residues with minimal overlap were determined. Of the 147 ORFs, 143 appeared to be homologous to other baculovirus genes, and 4 were unique to AnpeNPV. Furthermore, there are still 29 and 33 conserved genes present in all baculoviruses and all lepidopteran baculoviruses respectively. In addition, the total number of genes common to all lepidopteran NPVs is sill 74, however the 74 genes are somewhat different from the 74 genes identified before because of some new sequenced NPVs. Only 6 genes were found exclusively in all lepidopteran NPVs and 12 genes were found exclusively in all Group I NPVs. AnpeNPV encodes <it>v-trex</it>(Anpe115, a 3' to 5' repair exonuclease), which was observed only in CfMNPV and CfDEFNPV in Group I NPVs. This gene potentially originated by horizontal gene transfer from an ancestral host. In addition, AnpeNPV encodes two <it>conotoxin</it>-like gene homologues (<it>ctls</it>), <it>ctl1 </it>and <it>ctl2</it>, which were observed only in HycuNPV, OpMNPV and LdMNPV. Unlike other baculoviruses, only 3 typical homologous regions (<it>hr</it>s) were identified containing 2~9 repeats of a 30 bp-long palindromic core. However, 24 perfect or imperfect direct repeats (<it>dr</it>s) with a high degree of AT content were found within the intergenic spacer regions that may function as non-<it>hr</it>, <it>ori</it>-like regions found in GrleGV, CpGV and AdorGV. 9 <it>dr</it>s were also found in intragenic spacer regions of AnpeNPV.</p> <p>Conclusion</p> <p>AnpeNPV belongs to Group I NPVs and is most similar to HycuNPV, EppoNPV, OpMNPV and CfMNPV based on gene content, genome arrangement, and amino acid identity. In addition, analysis of genes that flank <it>hr</it>s supported the argument that these regions are involved in the transfer of sequences between the virus and host.</p
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