Flutter parametric studies of cantilevered twin-engine transport type wing with and without winglet. Volume 2: Transonic and density effect investigations

Flutter characteristics of a cantilevered high aspect ratio wing with winglet were investigated. The configuration represented a current technology, twin engine airplane. Compressibility effects through transonic Mach numbers and a wide range of mass-density ratios were evaluated on a low speed and high speed model. Four flutter mechanisms were obtained from test, and analysis from various combinations of configuration parameters. It is shown that the coupling between wing tip vertical and chordwise motions have significant effect under some conditions. It is concluded that for the flutter model configurations studied, the winglet related flutter is amenable to the conventional flutter analysis techniques. The low speed model flutter and the high-speed model flutter results are described

Effects of winglet on transonic flutter characteristics of a cantilevered twin-engine-transport wing model

A transonic model and a low-speed model were flutter tested in the Langley Transonic Dynamics Tunnel at Mach numbers up to 0.90. Transonic flutter boundaries were measured for 10 different model configurations, which included variations in wing fuel, nacelle pylon stiffness, and wingtip configuration. The winglet effects were evaluated by testing the transonic model, having a specific wing fuel and nacelle pylon stiffness, with each of three wingtips, a nonimal tip, a winglet, and a nominal tip ballasted to simulate the winglet mass. The addition of the winglet substantially reduced the flutter speed of the wing at transonic Mach numbers. The winglet effect was configuration-dependent and was primarily due to winglet aerodynamics rather than mass. Flutter analyses using modified strip-theory aerodynamics (experimentally weighted) correlated reasonably well with test results. The four transonic flutter mechanisms predicted by analysis were obtained experimentally. The analysis satisfactorily predicted the mass-density-ratio effects on subsonic flutter obtained using the low-speed model. Additional analyses were made to determine the flutter sensitivity to several parameters at transonic speeds

Cashew research in India

Cashew, after its introduction from Brazil during the 16th Century, has established very well in India. A total of 40 high-yielding varieties have been released so far by the Directorate of Cashew Research, Puttur, and various Agricultural Universities, for cultivation. Of these, 13 are hybrids and 27 are selections. Research achievements in the area of crop improvement, management, protection and post-harvest technology over the last six decades are reviewed and documented here. As India has been importing raw nuts to the tune of 6.5 lakh tons annually to cater the demand of established processing factories, research priorities have been identified to meet the challenges of enhancing production and productivity of cashew in the country

Influence of Environmental Factors on Growth Rate of Crassostrea madrasensis (Preston) in Suspended Culture

Growth response of Crassostrea madrasensis to varying environmental factors in the Mulki estuary of Karnataka was investigated from April 2004 to March 2005. Temperature, salinity, pH, particulate organic matter (POM), particulate inorganic matter (PIM), total particulate matter (TPM) and chlorophyll a (Chl a) levels were correlated with growth in shell length. Marked seasonal patterns in growth rate were observed in relation to changes in environmental factors. Growth curve indicated a rapid phase (16.21±1.2 mm month-1) initially (May-June) followed by a slow phase (0.8±0.52 mm month-1) coinciding with the drop in salinity (August-September). Considering the temporal variations of environmental factors, their influence on growth rate was analysed seasonally. The growth rate was significantly correlated with Chl a concentrations in all the seasons. A pronounced seasonal cycle was noticed in Chl a levels resulting from blooms in pre-monsoon (April-May) and post-monsoon (October) seasons

1-{4-Chloro-2-[2-(2-fluoro­phen­yl)-1,3-dithio­lan-2-yl]phen­yl}-2-methyl-1H-imidazole-5-carbaldehyde

There are two mol­ecules in the asymmetric unit of the title imidazole derivative, C20H16ClFN2OS2. In one mol­ecule, the dithiol­ane ring is disordered over two positions in a 0.849 (9):0.151 (10) ratio. The imidazole ring makes dihedral angles of 79.56 (9) and 18.45 (9)° with the 4-chloro­phenyl and 2-fluoro­phenyl rings, respectively, in one mol­ecule; in the other mol­ecule, the corresponding angles are 82.72 (9) and 17.39 (10)°. In the crystal, mol­ecules are linked by weak C—H⋯O inter­actions and these linked mol­ecules are stacked along the b axis by π–π inter­actions with a centroid–centroid distance of 3.4922 (11) Å. In addition, π–π inter­actions between the imidazole and 2-fluoro­phenyl rings are also observed, with centroid–centroid distances of 3.4867 (11) and 3.4326 (10) Å. The crystal is further consolidated by weak C—H⋯π inter­actions. Cl⋯S [3.5185 (8) Å], C⋯O [3.192 (3) Å] and C⋯C [3.326 (2)–3.393 (3) Å] short contacts are also observed

Benzyl N-{2-[5-(4-chloro­phen­yl)-1,2,4-oxadiazol-3-yl]propan-2-yl}carbamate

In the title 1,2,4-oxadiazole derivative, C19H18ClN3O3, the 1,2,4-oxadiazole ring makes dihedral angles of 12.83 (8) and 4.89 (8)°, respectively, with the benzyl and 4-chloro­phenyl rings, while the dihedral angle between the benzyl and 4-chloro­phenyl rings is 11.53 (7)°. In the crystal, mol­ecules are linked by N—H⋯N hydrogen bonds into helical chains along the b axis. A weak C—H⋯π inter­action is also present

4-Hydrazinyl-1-isobutyl-1H-imidazo[4,5-c]quinoline

In the title compound, C14H17N5, the 1H-imidazo[4,5-c]quinoline ring system is essentially planar, with a maximum deviation of 0.0325 (7) Å. In the crystal, a pair of inter­molecular N—H⋯N hydrogen bonds link neighbouring mol­ecules, forming an inversion dimer and generate an R 2 2(10) ring motif. These dimers are further connected into a chain along the b axis via inter­molecular C—H⋯N hydrogen bonds, resulting in an R 2 2(14) ring motif

4-Chloro­benzaldehyde (1-isobutyl-1H-imidazo[4,5-c]quinolin-4-yl)hydrazone monohydrate

In the title compound, C21H20ClN5·H2O, the 1H-imidazo[4,5-c]quinoline ring is approximately planar, with a maximum deviation of 0.0795 (7) Å, and it forms a dihedral angle of 7.65 (3)° with the chloro­phenyl ring. In the crystal, the components are linked into chains along the a axis via inter­molecular N—H⋯O, O—H⋯N and C—H⋯O hydrogen bonds. One of the H atoms of the water mol­ecule is disordered over two positions with a site-occupancy ratio of 0.80 (4):0.20 (4)

1-Isobutyl-N,N-dimethyl-1H-imidazo[4,5-c]quinolin-4-amine

In the title compound, C16H20N4, the 1H-imidazo[4,5-c]quinoline ring system is approximately planar, with a maximum deviation of 0.0719 (15) Å. An intra­molecular C—H⋯N hydrogen bond contributes to the stabilization of the mol­ecule, forming an S(6) ring motif. In the crystal, the mol­ecules are stacked along the b axis through weak aromatic π–π inter­actions between benzene and imidazole and benzene and pyridine rings [centroid–centroid distances = 3.6055 (10) and 3.5342 (10) Å, respectively]