Periodic orbits of the second kind in the restricted three-body problem when the more massive primary is an oblate spheroid

Utilizing secular perturbing potential due to oblateness, the existence of periodic orbits of the second kind is established through analytic continuation using Delaunay's canonical variables in the planar restricted three-body problem when the more massive primary is an oblate spheroid with its equatorial plane coincident with the plane of motion.     

Heat and mass transfer of an oscillatory flow with Hall current,II

An analysis of Hall current on the combined effects of thermal and mass diffusion of an electrically conducting liquid past an infinite vertical porous plate is performed. Analytical expressions for the transient velocity, the transient temperature in the boundary layer and the skin-friction on the plate are derived. The effects of various parameters on the velocity, temperature, shearing stresses and rate of heat transfer are shown by graphs and tables.     

Tectonic significance of Eocene and Cretaceous radiolaria from South Andaman Island, northeast Indian Ocean

Abstract Eocene (Middle) and Cretaceous (Campanian) radiolarian faunas from the basement rocks of the southern part of South Andaman Island in the northeastern Indian Ocean affirm the sedimentological hiatus that encompassed part of the Paleocene to Early Eocene ages in these islands, and its extension northward to Indoburma region and south to the outer islands of the Sunda Arc.     

Studies on the Relative Toxicity of few Synthetic Detergents to a Fish Macrones vittatus

In the present investigation static bioassay studies have been made with few synthetic detergents so as to determine the 50 per cent lethal concentration (Lc₅₀) and harmless concentrations. The Lc₅₀ values of these detergents ranged from 0.28 to 1.73 mg/1 (from 6 to 96 hours). The Swascofix E45 is the most highly toxic and Swascol 4 L the least toxic detergent and the other lies between them. The safe concentrations for different detergents have been worked out. On the basis of these data it is suggested that a lot of treatment or dilution is necessary for the safe disposal of these detergent wastes. The regression equation was developed for each detergent for 6, 24, 48, 72 and 96 hours interval and the values of Y have been calculated for each time. From these lines, it is clear that an almost straight-line correlation exists between the concentration and the the survival number.     

Evidence of multiplicity in the P-travel time curve beyond 30 degrees

Slowness measurements on first and later arrivals from earthquakes in the Philippine and Taiwan regions recorded at the Warramunga array in Australia indicate abrupt decreases in slowness of the first arrival as well as triplications in the travel time curve at epicentral distances of about 38 and 43°. These results imply the presence of regions of rapid or discontinuous velocity increase at depths of about 900 and 1050 km, respectively. Between these regions of sharp velocity increases the dT/dΔ measurements indicate that the velocity gradients are lower than those determined by previous investigators. The observed extensions of the 650- and 770-km branches out to 50° can be explained in terms of the triplications if small negative velocity gradients of the order of 0.1 km/s per 100 km exist between 650–770 and 770–900 km depths. An alternative explanation of these observed extensions may be provided in terms of underside reflections from the bottom of the velocity discontinuities. Either of the two explanations require sharp velocity gradients at the depth of the velocity discontinuities. These observations are at variance with earth models where the P-wave velocity increases continuously with depth below a depth of 650 km.     

On the stresses produced by impulsive displacemens applied to the inner surface of a spherical cavity

Summary In this note displacements and stresses produced in an infinite elastic solid by impulsive radial and twisting displacements applied to the inner surface of a spherical cavity have been determined.     

On the seismic structure of Indian upper-mantle regions

Several velocity models on upper mantle regions of the world have been postulated during the last two decades. There has been a broad agreement amongst seismologists that upper mantle has got two transition zones, though the models differ in detail. These zones have been found to occur around ‘400 km’ and ‘650 km’ depth ranges with varying thicknesses of the zones. A limited number of such studies have been made on the upper mantle structure of the Indian subcontinent. High positive velocity gradients were reported to exist around the above depth range. Evidence for lateral heterogeneities has also been found. We address some problems like refinement of Indian upper mantle velocity models specially after considering the effect of scattering and attenuation on the short periodP-waves. The study of proper positioning of the cusps of the travel-time branches and their extension is essential as well. In our opinion, analysis of such problems would help in the better understanding of the nature of propagation of seismic waves and mechanism of earthquakes. Complexity of seismic signatures observed is another major problem and may also be taken into consideration.     

On frequency magnitude and energy of significant Indian earthquakes

Summary Frequency, magnitude and energy of Indian earthquakes with magnitude greater than 5 has been studied. The Indian regions can be divided into three main seismically active regions, viz. 1. Delhi and Himalayan region, 2. Assam region and 3. Koyana region which includes southwest India. The relations between frequency-magnitude and energy-magnitude of earthquakes are shown in Fig. 3 and 4 respectively. Further a relationship, logN=p+q logE type has been established for frequency and energy of Indian earthquakes and the values of constantsp andq have been determined for all the three seismic regions. The results thus obtained are good and satisfactory.     

Complex seismic signatures and narrow azimuthal study of Hindukush earthquakes

About eighty earthquakes, exclusively from the Hindukush region, which were recorded at Gauribidanur seismic array (GBA) have been used in the present study. Short periodP-wave recordings upto 36 seconds were processed using adaptive cross-correlation filtering technique. The main objective of this exercise was to examine the signal complexities and seismic ray direction anomalies of these earthquakes which have identical epicentral distances and a narrow azimuthal range from GBA but different focal depths from 10 to 240 km. Slowness anomalies of the order of 1–4 sec/deg and azimuthal anomalies upto 6° have been found in this case. These deviations have been attributed to the upper mantle region between source and the receiver. Analysis of the data reveals that most of the events occurring at shallower depths had complex signatures as compared to the deeper events. The structure near the source region, complicated source functions and scattering confined to the crust-upper mantle near source are mainly responsible for complexity of the observed signals as the transmission path of the ray tubes from turning point to the recording stations is practically the same.     

Spatial Variability of Turbulent Fluxes in the Roughness Sublayer of an Even-Aged Pine Forest

The spatial variability of turbulent flow statistics in the roughness sublayer (RSL) of a uniform even-aged 14 m (= h) tall loblolly pine forest was investigated experimentally. Using seven existing walkup towers at this stand, high frequency velocity, temperature, water vapour and carbon dioxide concentrations were measured at 15.5 m above the ground surface from October 6 to 10 in 1997. These seven towers were separated by at least 100m from each other. The objective of this study was to examine whether single tower turbulence statistics measurements represent the flow properties of RSL turbulence above a uniform even-aged managed loblolly pine forest as a best-case scenario for natural forested ecosystems. From the intensive space-time series measurements, it was demonstrated that standard deviations of longitudinal and vertical velocities (_u, _w) and temperature (_T) are more planar homogeneous than their vertical flux of momentum (u_* ²) and sensible heat (H) counterparts. Also, the measured H is more horizontally homogeneous when compared to fluxes of other scalar entities such as CO₂ and water vapour. While the spatial variability in fluxes was significant (>15 %), this unique data set confirmed that single tower measurements represent the canonical structure of single-point RSL turbulence statistics, especially flux-variance relationships. Implications to extending the moving-equilibrium hypothesis for RSL flows are discussed. The spatial variability in all RSL flow variables was not constant in time and varied strongly with spatially averaged friction velocity u_*, especially when u_* was small. It is shown that flow properties derived from two-point temporal statistics such as correlation functions are more sensitive to local variability in leaf area density when compared to single point flow statistics. Specifically, that the local relationship between the reciprocal of the vertical velocity integral time scale (I_w) and the arrival frequency of organized structures (/h) predicted from a mixing-layer theory exhibited dependence on the local leaf area index. The broader implications of these findings to the measurement and modelling of RSL flows are also discussed.