Comparison of acoustic instruments in an atmospheric turbulent flow over water     

M. Miyake  R. W. Stewart  R. W. Burling  L. R. Tsvang  B. M. Koprov  O. A. Kuznetzov 《Boundary-Layer Meteorology》1971,2(2):228-245

In the fall of 1968 an International Intercomparison Experiment was conducted to compare, among other things, acoustic anemometers designed for measurements of atmospheric turbulence. Excellent agreement was obtained in measurements of the vertical component, but an important discrepancy was revealed in measurements of the downwind velocity. The discrepancy proved far more significant in the cospectra than in the spectra themselves. It is evident that great care must be taken in the design of such instruments. An acoustic instrument was shown to have insufficient signal-to-noise ratio to serve as a thermometer under the near-neutral conditions often encountered over water.Comparison of the data-handling and data-analysis techniques showed that although the methods differed widely, the results were essentially identical.  相似文献   

UNDERGROUND WATERS NOW UNDEVELOPED     

Stewart L. Udall 《Ground water》1967,5(4):2-5

  相似文献   

Relativistically induced instellar density fluctuations     

P. Stewart 《Astrophysics and Space Science》1973,24(1):269-277

The spectrum of cold electron density fluctuations induced by a relativistic electron gas is investigated and the results discussed in relation to the interstellar medium.  相似文献   

Aleutian Strain Events: Observations and Interpretation     

J. H. Pfluke  R. M. Stewart 《Geophysical Journal International》1973,35(1-3):229-241

  相似文献   

Evolution of Planetesimal Velocities Based on Three-Body Orbital Integrations and Growth of Protoplanets     

Keiji OhtsukiGlen R. Stewart  Shigeru Ida 《Icarus》2002,155(2):436-453

We obtain the viscous stirring and dynamical friction rates of planetesimals with a Rayleigh distribution of eccentricities and inclinations, using three-body orbital integration and the procedure described by Ohtsuki (1999, Icarus137, 152), who evaluated these rates for ring particles. We find that these rates based on orbital integrations agree quite well with the analytic results of Stewart and Ida (2000, Icarus 143, 28) in high-velocity cases. In low-velocity cases where Kepler shear dominates the relative velocity, however, the three-body calculations show significant deviation from the formulas of Stewart and Ida, who did not investigate the rates for low velocities in detail but just presented a simple interpolation formula between their high-velocity formula and the numerical results for circular orbits. We calculate evolution of root mean square eccentricities and inclinations using the above stirring rates based on orbital integrations, and find excellent agreement with N-body simulations for both one- and two-component systems, even in the low-velocity cases. We derive semi-analytic formulas for the stirring and dynamical friction rates based on our numerical results, and confirm that they reproduce the results of N-body simulations with sufficient accuracy. Using these formulas, we calculate equilibrium velocities of planetesimals with given size distributions. At a stage before the onset of runaway growth of large bodies, the velocity distribution calculated by our new formulas are found to agree quite well with those obtained by using the formulas of Stewart and Ida or Wetherill and Stewart (1993, Icarus106, 190). However, at later stages, we find that the inclinations of small collisional fragments calculated by our new formulas can be much smaller than those calculated by the previously obtained formulas, so that they are more easily accreted by larger bodies in our case. The results essentially support the previous results such as runaway growth of protoplanets, but they could enhance their growth rate by 10-30% after early runaway growth, where those fragments with low random velocities can significantly contribute to rapid growth of runaway bodies.  相似文献   

Remineralization Ratios in the Subtropical North Pacific Gyre   总被引：2，自引：0，他引：2  

Yuan-Hui Li  David M. Karl  Christopher D. Winn  Fred T. Mackenzie  Kathleen Gans 《Aquatic Geochemistry》2000,6(1):65-85

Based on a new mixing model of two end-members, the water column remineralization ratios of P/N/C_org - O₂ = 1/13 ± 1/135 ± 18/170 ± 9 are obtained for the Hawaii Ocean Time-series (HOT) data set at station ALOHA. The traditional Redfield ratios of P/N/C_org/–O₂ = 1/16/106/138 have standard deviations of more than 50%, when they are based on the average composition of phytoplankton. Apparently, the remineralization processes in the water column have smoothed out the observed large variability of plankton compositions. A new molar formula for the remineralized plankton may be written as ₁₃₅H₂₈₀O₁₀₅N₁₃P or C₂₅(CH₂O)₁₀₁(CH₄)₉(NH₃)₁₃(H₃PO₄). Oxidation of this formula results inC₂₅(CH₂O)₁₀₁(CH₄)₉(NH₃)₁₃(H₃PO₄) + 170O₂ 135CO₂ + 132H₂O + 13NO₃ ^- + H₂PO₄ ^- + 14H⁺.For comparison, remineralization using Redfield's formula gives:(CH₂O)₁₀₆(NH₃)₁₆(H₃PO₄) + 138O₂ 106CO₂ + 122H₂O + 16NO₃ ^-+ H₂PO₄ ^- + 17H⁺  相似文献   

Editorial     

John Wilson  Stewart Fotheringham  Gary Hunter  Jochen Albrecht 《Transactions in GIS》2006,10(2):153-153

  相似文献   

Ten Years On . . .     

John Wilson  Stewart Fotheringham  Gary Hunter  Jochen Albrecht 《Transactions in GIS》2006,10(3):333-333

  相似文献   

The Green Revolution re-assessed: Insider perspectives on agrarian change in Bulandshahr District, Western Uttar Pradesh, India     

Sarah Jewitt  Kathleen Baker 《Geoforum》2007,38(1):73-89

In spite of raising Asian per capita food production by 27% and making India food self-sufficient, the Green Revolution has received much criticism for its environmental and socio-economic impacts. Taking on board post-development critiques of ‘speaking for’ Third World ‘others’, this paper seeks to examine the Green Revolution from the points of view of people directly affected by it. Comparative, historically-informed research in three villages for which 1972 baseline data exist reveal that the Green Revolution has ensured, in the words of one marginal farmer that ‘nobody sleeps with an empty stomach nowadays’. Most villagers associate the Green Revolution with increases in living standards and weakening community-based wealth hierarchies. Nevertheless, socio-economic inequalities between certain Scheduled Castes and other villagers are still very apparent.  相似文献   

A method for generating uniform size-segregated pyrite particle fractions     

Amy L Wolfe  Ran Liu  Brian W Stewart  Rosemary C Capo  David A Dzombak 《Geochemical transactions》2007,8(1):9

Background  

Standardized sample preparation techniques allow comparison of pyrite dissolution experiments under diverse conditions. Our objective was to assess dry and wet sieving preparation methodologies, and to develop a reproducible technique that yields uniformly size-distributed material within a limited size range of interest.  相似文献