Gas-partitioning tracer test to quantify trapped gas during recharge     

Heilweil VM  Solomon DK  Perkins KS  Ellett KM 《Ground water》2004,42(4):589-600

Dissolved helium and bromide tracers were used to evaluate trapped gas during an infiltration pond experiment. Dissolved helium preferentially partitioned into trapped gas bubbles, or other pore air, because of its low solubility in water. This produced observed helium retardation factors of as much as 12 relative to bromide. Numerical simulations of helium breakthrough with both equilibrium and kinetically limited advection/dispersion/retardation did not match observed helium concentrations. However, better fits were obtained by including a decay term representing the diffusive loss of helium through interconnected, gas-filled pores. Calculations indicate that 7% to more than 26% of the porosity beneath the pond was filled with gas. Measurements of laboratory hydraulic properties indicate that a 10% decrease in saturation would reduce the hydraulic conductivity by at least one order of magnitude in the well-sorted sandstone, but less in the overlying soils. This is consistent with in situ measurements during the experiment, which show steeper hydraulic gradients in sandstone than in soil. Intrinsic permeability of the soil doubled during the first six months of the experiment, likely caused by a combination of dissolution and thermal contraction of trapped gas. Managers of artificial recharge basins may consider minimizing the amount of trapped gas by using wet, rather than dry, tilling to optimize infiltration rates, particularly in well-sorted porous media in which reintroduced trapped gas may cause substantial reductions in permeability. Trapped gas may also inhibit the amount of focused infiltration that occurs naturally during ephemeral flood events along washes and playas.  相似文献   

Canonical orbital elements in terms of an arbitrary independent variable     

Victor R. Bond  Guy Janin 《Celestial Mechanics and Dynamical Astronomy》1981,23(2):159-172

Within the framework of the Hamiltonian mechanics in the extended phase space, a set of canonical elements of the Delaunay type is developed in terms of an arbitrary independent angular variable. Application to the four classical anomalies-eccentric, true, elliptic, and mean-is presented. Particular attention is given to the generalized time equation and its conjugate energy equation.  相似文献   

An electron temperature distribution derived from optical and radio measurements of HII regions     

Victor Mansfield 《Astrophysics and Space Science》1969,3(2):292-300

Radio measurements of the electron temperature ofHii regions are obtained from the ratio of the brightness temperature of a hydrogen recombination line to that of the adjacent continuum, while optical measurements are obtained from the ratio of [Oiii] forbidden-line intensities. The radio and optical measurements made under the assumption of an isothermalHii region,T _R andT _opt respectively, are combined to derive a temperature distribution for an entire nebula. A sphericalHii region in local thermodynamic equilibrium with constant density which is optically thin in both the line and the continuum is used as a model. Assuming linear temperature gradients withT _R=6000K andT _opt=10000K, it is found thatT=12000K (1–0.74r/R), wherer is the distance from the center andR is the radius of the nebula.  相似文献   

On the Solution of Inverse Eigenvalue Problems of high Orders     

Victor Barcilon 《Geophysical Journal International》1974,39(1):143-154

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The accuracy of altimétric surfaces     

Carl WunSCh  Victor Zlotnicki 《Geophysical Journal International》1984,78(3):795-808

Summary. Estimates of the shape of the sea surface as determined from satellite altiméters have become of increasing importance in geophysics, geodesy and physical oceanography. The most effective error reduction procedures used in producing these surfaces have been some version of a crossing-arc analysis. The problem with this procedure is the absence of an easy means of evaluating the noise structure of the final result. By recasting the problem as one of objective mapping (optimal estimation) we both optimize the error reduction and obtain an explicit estimate of the wave-number structure of the final altimétric surface. Examples, suitable to a small computer, have been generated to show that the error reduction along the sub-satellite tracks is very great, with most of the residual lying in long wavelengths.  相似文献   

Determination of the potential in a synodic system     

Victor Szebehely  R. Broucke 《Celestial Mechanics and Dynamical Astronomy》1981,24(1):23-26

Determination of the potential field in a fixed (inertial) system may be accomplished by the solution of a homogeneous linear partial differential equation when a family of orbits of a body moving in the field is given. This partial differential equation was presented and thoroughly analyzed earlier. The present paper discusses the same problem in a rotating system where the centrifugal and Coriolis effects render the pertinent partial differential equation in general non-homogeneous and non-linear. A linear, though non-homogeneous, partial differential equation for the determination of the synodic potential is obtained only in the special case of iso-energetic families of orbits.  相似文献   

Surfaces of zero velocity in the restricted problem of three bodies     

John Lundberg  Victor Szebehely  R. Steven Nerem  Byron Beal 《Celestial Mechanics and Dynamical Astronomy》1985,36(2):191-205

Recent uses of computer graphics allow the representation of the three-dimensional surfaces of zero velocity, also known as Hill's or the Jacobian surfaces. The purpose of this paper is to show the actual surfaces rather than their projections which are available in the standard literature. The analytical properties of the surfaces are also available; therefore, this paper offers the pertinent references rather than the derivations.  相似文献   

Well-posed Inverse Eigenvalue Problems     

Victor Barcilon 《Geophysical Journal International》1975,42(2):375-383

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Limits of predictability of gravitational systems     

Victor Szebehely 《Celestial Mechanics and Dynamical Astronomy》1987,43(1-4):139-145

The concept of finite predictability of gravitational many-body systems is related to the non-deterministic nature of celestial mechanics and of dynamics, in general. The basic, fundamental reasons for the uncertainty of predictions are as follows: (1) the initial conditions are known only approximately since they are obtained either from observations or from approximate computations; (2) the equations of motion given by a selected model describe the actual system only approximately; (3) the physical constants of the dynamical system have error limits; (4) the differential equations of motion are non-integrable and numerical integration methods must be used for solution, generating errors in the final result at every integration step.In addition to these reasons, mostly depending on our techniques, there are some more fundamental reasons depending on the nature of the dynamical system investigated. These are the appearance of regions of instability, non-integrability and chaotic motion.Details, effects and controls of these regions for finite predictability are discussed for various dynamical systems of importance in celestial mechanics with special emphasis on planetary systems.  相似文献   

Carlin-type Gold Prospects in Surigao del Norte, Mindanao Island, Philippines: Their Geology and Mineralization Potential     

Victor B. Maglambayan    Sj Montes    Katherine Hipol    Maireen Mamitag    Rikki Pamela Pineda    Raymond Rodolfo    Noel Oliveros  Antonio Sy 《Resource Geology》2005,55(3):145-154

Abstract. Three calcareous sedimentary rock-hosted Carlin type-like gold prospects were mapped in a mineral production sharing agreement area of Philex Gold Philippines Inc. in Taganaan municipality, Surigao del Norte province in Mindanao island in the Philippines. They occur along a 20–25 km long trend of known epigenetic gold and porphyry copper deposits that lie close to several splays of the Philippine Fault Zone. The gold district forms part of the Late Cretaceous Eastern Mindanao Range that hosts early Paleogene and late Pliocene to Quaternary intrusive rocks.
Gold is invisible in the jasperoid outcrops in Lascogon, Napo, and Danao prospects. The jasperoids occur in lenses of marls belonging to the Taganaan Marl Member that is associated to a turbiditic member of the Middle Miocene Mabuhay Formation. The marl lenses include gently dipping interbedded silty limestones and calcareous shales. The "invisible gold" mineralization in silicified calcareous rocks resembles Carlin-type deposits. Based on the mapped igneous and sedimentary rocks, a possible heat source for the gold mineralization is either or both of the two main phases of intrusion, Mabuhay An-desite or Alipao Andesite Porphyry. Forty-eight rock samples, fifteen stream sediment samples, and one soil sample were critical in delineating the general features of the potential Carlin-type prospects. The gold grades of jasperoids in the three prospects range from trace amounts to 20 g/t Au. Regional studies of gold and porphyry copper mineralization in the Surigao del Norte mineral district are important in delineating ore targets for drilling in the three prospects.  相似文献