Descriptive statistics for N -dimensional closed arrays: A spherical coordinate approach

Recent publications have demonstrated that the composition of a system can be described by the angles which define the vector resulting from the projection of the composition onto the unit hypersphere. Although published trigonometric relationships allow determination of the angles in any number of dimensions, no general hyperdimensional recursive formulae exist for the calculation of these quantities and their variances and covariances. A general methodology for calculating the angles which describe the compositions of systems in any number of dimensions is presented. These angles can be used to calculate statistics (central moments and resultant vectors) describing the central tendency and dispersion among rock compositions, as well as to quantify the angular differences between compositions. Equations that relate the variances and covariances of these angular variables to the variances and covariances of the actual component proportion variables are presented, allowing projection of these measurements from one reference frame to another (cartesian to spherical and vice versa).     

Feeding ecology of the northern pipefish,Syngnathus fuscus,in a seagrass community of the lower Chesapeake Bay

Examination of gut contents of the northern pipefish,Syngnathus fuscus, revealed that gammarid amphipods, caprellid amphipods, isopods, and calanoid copepods were the dominant food items during the sevenmonth study period.Gammarus mucronatus, calanoid copepods, andErichsonella attenuata were the seasonally dominant prey items in the spring, summer, and fall, respectively.G. mucronatus and calanoid copepods were consumed in approximate proportion to their numerical abundance in the environment, whileE. attenuata, present in rather uniform densities throughout the study period, was extensively consumed only in the late summer and fall. An ontogenetic pattern of prey consumption was evident, in addition to the seasonal pattern. Comparison ofG. mucronatus andE. attenuata size ranges from the field and in pipefish guts revealed thatS. fuscus preyed upon the smaller size classes of each species, and that mean size of prey consumed was positively related to fish size.     

Effects of mesoscale atmospheric convection cells on the waters of the East China Sea

Currents and atmospheric parameters were measured in the East China Sea in February, 1975, as part of the AMTEX'75 program. These data were used to describe outbreaks of cold continental air over this warm and shallow sea. Particular emphasis was placed on describing the structure of mesoscale atmospheric cells embedded in the outbreaks and the effects of these cells on the water column.Two cold air outbreaks were recorded. Heat fluxes (latent plus sensible) as high as 1270 cal/cm² day were calculated. Evidence of mesoscale atmospheric cells was found during outbreaks in satellite imagery and in solarimeter data. The development of mesoscale cells was described by correlating fluctuations in the air temperature and absolute humidity records. The cells were found to be best developed when satellite imagery showed that they were of the closed variety. The data suggest that cellular activity matures from open to closed cell types.During the period of greatest development, a representative closed cell was 24–30 km in diameter, moved at 8 m s^-1 over the spar buoy, had a temperature fluctuation of 0.4 °C, an absolute humidity fluctuation of 0.4 g kg^-1, and wind speed and heat flux fluctuations of - 12.5%.A non-dimensional index, formed from the fluctuations of the air temperature and absolute humidity records, was used to indicate the passage of mesoscale atmospheric cells over the measuring site. Using this index as input and the fluctuations in the oceanic parameters at a depth of 20 m as output, it was found that the passage of mature cells was significantly correlated with temperature fluctuations and current fluctuations aligned 25 ° to the right of the wind about 45 min later.     

Acoustic echo-sounding techniques and their application to gravity-wave,turbulence, and stability studies

This paper is a brief summary of recent experimental studies conducted by the WPL staff in order to: (a) compare acoustic echo strengths with those predicted from measured turbulence intensities and scatter theory; (b) develop optimum experimental geometries for Doppler work, and (c) use the acoustic echo-sounder as a quantitative tool in studies of gravity wave dynamics in, and immediately above, the stable planetary boundary layer. We find that the observed acoustic echo strengths are roughly an order of magnitude greater than those predicted theoretically. This discrepancy might be in part due to partial reflection although the comparison is somewhat clouded by uncertainties in our knowledge of the equipment characteristics, propagation losses, etc. Comparisons between Doppler and in situ wind measurements give confidence in the Doppler results, but further experimentation and comparisons are needed. Preliminary use of acoustic Doppler data in a case study of gravity-wave dynamics in the planetary boundary layer has yielded boundary-layer wind speed and direction profiles which give insight into the mechanisms responsible for the wave generation. The Doppler data yield estimates of the wave associated momentum fluxes (a few dyn cm^–2) as well. The results derived from the acoustic techniques are quite encouraging, but thus far remain unsubstantiated by independent wind and flux measurements.     

The role of zinc-xanthate precipitation in sphalerite flotation

Flotation of sphalerite with ethyl, propyl, butyl, amyl, and hexyl xanthate is presented as a function of pH and concentration. Surface species have been identified with infrared spectroscopy and correlated with flotation and electrophoretic results. Flotation is postulated to be controlled by the formation and adsorption of bulk precipitated zinc xanthate on the alkyl chains of chemisorbed collector species.     

Three-dimensional benchmark for variable-density flow and transport simulation: matching semi-analytic stability modes for steady unstable convection in an inclined porous box

This benchmark for three-dimensional (3D) numerical simulators of variable-density groundwater flow and solute or energy transport consists of matching simulation results with the semi-analytical solution for the transition from one steady-state convective mode to another in a porous box. Previous experimental and analytical studies of natural convective flow in an inclined porous layer have shown that there are a variety of convective modes possible depending on system parameters, geometry and inclination. In particular, there is a well-defined transition from the helicoidal mode consisting of downslope longitudinal rolls superimposed upon an upslope unicellular roll to a mode consisting of purely an upslope unicellular roll. Three-dimensional benchmarks for variable-density simulators are currently (2009) lacking and comparison of simulation results with this transition locus provides an unambiguous means to test the ability of such simulators to represent steady-state unstable 3D variable-density physics.