Time Of Maximum Value Research Articles

Investigation of Roll Pitch Yaw Phenomena for a Finned Store Released from a Wing

In this article, the commercial software CFD FASTRAN is applied to study the roll, pitch and yaw phenomena of turbulent flows around a finned store released from a wing. The three-dimensional, unsteady Navier-Stokes equations and k-e turbulent model are solved in the Cartesian coordinate system. The Chimera two-block grid system is utilized, and grid communication among two blocks are automatically implemented. To evaluate the accuracy of the present calculation, the calculated instantaneous trajectories of center of gravity of store, angles of roll, pitch and yaw, velocities and angular rates are compared with those of experimental data. The satisfactory agreement is achieved. Then, computations of different values of Mach number and ejector force applied on the store are carried out to investigate the unsteady roll, pitch and yaw phenomena of the separated store. The maximum value of pitch rate of the store decreases as the Mach number increases, and time of maximum value of yaw rate shortens as well. Both roll and yaw rates decrease as the ejector force applied on the store increases, and time of maximum value of roll, pitch and yaw rates shortens as well.

Export mechanisms for dissolved organic carbon and nitrate during summer storm events in a glaciated forested catchment in New York, USA

AbstractNitrate and dissolved organic carbon (DOC) concentrations during a summer storm for a forested catchment in the Adirondack Mountains displayed a clear separation in trajectories and timing of maximum values. Nitrate concentrations peaked early on the rising limb of the hydrograph, whereas DOC concentrations gradually increased through the rising limb with maximum concentrations following the discharge peak. Solute data from precipitation, throughfall, soilwater, and ground/till water indicated till water and near‐surface soil waters as the controlling end members for stream NO3− and DOC concentrations respectively. Streamflow concentrations of major base cations (Ca2+ and Mg2+), which were assumed to represent water originating from deep flow paths, matched the NO3− trajectory. These data suggest that streamflow NO3− concentrations are derived from till groundwater and that DOC is derived from near‐surface soil waters. We attributed the early expression of NO3− to the displacement of till waters by infiltrating precipitation. In contrast, we hypothesized that the delayed DOC concentrations occurred with surface and near‐surface runoff from near‐stream wetlands/peatlands and isolated saturated areas that became connected only under conditions of maximum water content in the catchment. Copyright © 2004 John Wiley & Sons, Ltd.

Surface level measurements of ozone and precursors at coastal and offshore locations in the Gulf of Maine

The northeastern United States has episodic high ozone several times each year at locations remote from urban and industrial centers. Extended measurements of ozone and the ozone precursors, volatile organic compounds (VOC) and nitrogen oxides, were made at Acadia National Park, Cape Elizabeth, and other coastal Maine locations during the North Atlantic Regional Experiment (NARE) intensive. In addition, ozone was measured from a commercial ferry, the Scotia Prince, in the Gulf of Maine where ozone concentrations up to 129 ppb were observed. Two high‐ozone episodes were observed during late August 1993 when ozone was greater than 90 ppb along much of the Maine coast. NOy concentrations at Acadia averaged 2.0 ppb (±1.97), maximum 12.0 ppb. During the high‐ozone episodes, NOy had linear relationships to ozone with slopes of 4–16. The timing of maximum values and extent of the high‐ozone air mass suggests that urban plumes transported over the Gulf of Maine are brought inland by sea breezes to the coastal regions but not to the interior areas of Maine.

Circadian, Ultradian, and Episodic Release ofβ-Endorphin in Men, and Its Temporal Coupling with Cortisol*

beta-Endorphin and ACTH derive from a common peptide precursor. Although much is known about the physiological patterns of ACTH release, neither the minute to minute regulation of beta-endorphin secretion nor its temporal relationship to cortisol has been characterized. As an initial step to defining the regulation of beta-endorphin release in man, we studied the circadian periodicity, ultradian rhythmicity, and episodic pulsatility of serum beta-endorphin concentrations in seven normal men. Blood sampling was conducted at 10-min intervals for 24 h, and the subsequent serum samples were assayed by a two-site immunoradiometric assay. Computerized analysis of the subsequent beta-endorphin time series revealed a mean beta-endorphin pulse frequency of 13 +/- 1 (+/- SE) peaks/24 h, corresponding to an interpulse interval of 100 +/- 7 min. The mean maximal peak height of beta-endorphin pulses was 31 +/- 3 pg/mL (9.0 +/- 0.8 pmol/L), which represented an incremental increase of 11 +/- 1 pg/mL 3.2 +/- 0.4 pmol/L; 63 +/- 13%) above the preceding nadir. The average beta-endorphin peak exhibited a duration of 68 +/- 6 min. Fourier analysis revealed a significant circadian amplitude of 6 +/- 1 pg/mL (1.6 +/- 0.4 pmol/L; 23% of the 24-h mean concentration), with an acrophase (time of maximum value) at 1043 h (+/- 40 min). Spectral analysis also disclosed beta-endorphin rhythms with mean periodicities of 29 +/- 4, 42 +/- 4, and 61 +/- 5 min. Gel filtration chromatography confirmed that serum beta-endorphin peaks contained significantly more immunoactive beta-endorphin [62 pg/mL (18 pmol/L)] than did the flanking nadirs [16 and 18 pg/mL (4.6 and 5.2 pmol/L)]. Auto- and cross-correlation analyses of serum beta-endorphin and cortisol concentrations followed by autoregressive modeling disclosed that all seven men had significant positive cross-correlations between serum beta-endorphin and cortisol considered simultaneously or when cortisol lagged beta-endorphin by 10 min. A negative cross-correlation was found in five of the seven men when cortisol was considered to lead beta-endorphin by 20 or 30 minutes. We conclude that beta-endorphin is released physiologically in a pulsatile manner with circadian and ultradian rhythmicity and a close temporal coupling to cortisol.

Ozone in the upper troposphere from gasp measurements

Several aspects of tropospheric ozone variations are examined by using ozone measurements made from commercial airliners (Gasp data). The east‐west variations of ozone have a predominant wavelength near 2400 km, by visual inspection of the autocorrelation function, while temperature and wind have predominant wavelengths near 3300 km. The different wavelengths may be due to a sampling bias. Distance‐lagged correlation functions of ozone with temperature and wind show a definite periodicity with wavelengths near 2400 km. The low correlation of ozone with meridional wind speed at lag zero makes it necessary to have many pairs of data to estimate even the sign of the meridional ozone flux with confidence. Tropical tropospheric ozone values above 100 parts per billion by volume (ppbv) appear to be associated with meridional transport from middle latitudes, and in some cases, relatively large tropical ozone values are coincident with clouds. A diurnal variation with amplitude near 2.0 ppbv is found with phase (time of maximum value) near 0800 LT at 32°–64°N but with phase near 1700 LT at 16°–32°N.