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Point source
About: Point source is a research topic. Over the lifetime, 5077 publications have been published within this topic receiving 94091 citations.
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TL;DR: In this paper, a fundamental solution for homogeneous reservoir in infinite space is derived by using the point source function with the consideration of the threshold pressure gradient, and the response curve of the dimensionless bottom hole pressure and the derivative for a horizontal well in the homogeneous gas reservoir are obtained.
Abstract: A fundamental solution for homogeneous reservoir in infinite space is derived by using the point source function with the consideration of the threshold pressure gradient. The fundamental solution of the continuous point source function is then derived based on the Green function. Various boundary conditions of the reservoirs are considered for this case and the corresponding solutions are obtained through the mirror image reflection and the principle of superimposition. The line source solution is obtained by integration. Subsequently, the horizontal-well bottom hole pressure response function for a non-linear gas flow in the homogeneous gas reservoir is obtained, and the response curve of the dimensionless bottom hole pressure and the derivative for a horizontal well in the homogeneous gas reservoir are obtained. In the end, the sensitivities of the relevant parameters are analyzed. The well test model presented in this paper can be used as the basis of the horizontal well test analysis for tight gas reservoirs.
40 citations
TL;DR: In this article, the authors present an analytic result for the magnification of a point source near a parabolic fold caustic, which is a higher-order approximation to the existing solution for a straight fold Caustic.
Abstract: When a source crosses the caustics of a gravitational microlens at cosmological distances, a high-magnification event occurs. This is seen as a change in the total flux of the image of the source. We present an analytic result for the magnification of a point source near a parabolic fold caustic. This is a higher-order approximation to the existing solution for a straight fold caustic. We show from a study of fold-crossing events that we can distinguish between disc and annular source geometries.
One important application of this work will be the determination of the geometric structure of the luminous regions of quasars. By observing the flux changes of a quasar image during a microlensing event, it is possible to determine features of quasar structure that would otherwise be below the resolution limit available with existing optical methods.
40 citations
TL;DR: In this article, the distortion of the mechanism of a double-couple point source located in an anisotropic medium is investigated when inverting waveforms using isotropic Green's functions.
40 citations
TL;DR: In this article, a multi-wavelength study of the overlapping error boxes of the unknown γ-ray sources TeV J2032+4130 and 3EG J2033+4118 in the direction of the Cygnus OB2 association (d = 1.7 kpc) was performed to search for a point-source counterpart of the first unidentified TeV source.
Abstract: We have made a multiwavelength study of the overlapping error boxes of the unidentified γ-ray sources TeV J2032+4130 and 3EG J2033+4118 in the direction of the Cygnus OB2 association (d = 1.7 kpc) in order to search for a point-source counterpart of the first unidentified TeV source. Optical identifications and spectroscopic classifications for the brighter X-ray sources in ROSAT PSPC and Chandra ACIS images are obtained, without finding a compelling counterpart. The classified X-ray sources are a mix of early- and late-type stars, with one exception. The brightest source in the Chandra observation is a new, hard absorbed source that is both transient and rapidly variable. It lies 7' from the centroid of the TeV emission, which places it outside of the claimed 2 σ location (r ≈ 48). A possible eclipse or "dip" transition is seen in its light curve. With a peak 1-10 keV luminosity of ≈7 × 1032(d/1.7 kpc)2 ergs s-1, this source could be a quiescent low-mass X-ray binary that lies beyond the Cyg OB2 association. A coincident, reddened optical object of R = 20.4, J = 15.4, H = 14.2, and K = 13.4 is observed but not yet classified as a result of the lack of obvious emission or absorption features in its spectrum. Alternatively, this Chandra and optical source might be a considered a candidate for a "proton blazar," a long hypothesized type of radio-weak γ-ray source. More detailed observations will be needed to determine the nature of this variable X-ray source and to assess the possibility of its connection with TeV J2032+4130.
40 citations
Patent•
10 Jan 2006
TL;DR: In this paper, a point source of light from which light is emitted through a lens toward a reflective surface of a liquid contained in a vessel is detected and a center of gravity representing inclination is determined from the data.
Abstract: Apparatus and methods for detecting inclination employ a point source of light from which light is emitted through a lens toward a reflective surface of a liquid contained in a vessel. Light reflected from the surface passes through the lens to form a defocused image of the point source on a two-dimensional array of detector elements. Data acquired from the array represents intensity of the light incident on each of the detector elements. A center of gravity representing inclination of the vessel is determined from the data.
40 citations