IMPROVED POINT-SOURCE AND LINE-SOURCE COMPACT ANTENNA RANGES

1967 ◽  
Author(s):  
Richard C. Johnson ◽  
Albert L. Holliman
Keyword(s):  
Point Source ◽  
Line Source ◽  
Compact Antenna

Determination of Dynamic Dispersion Coefficient for Solid Particles Flowing in a Fracture With Consideration of Gravity Effect

2020 ◽  
Vol 142 (5) ◽  
Author(s):  
Yanan Ding ◽  
Xiaoyan Meng ◽  
Daoyong Yang
Keyword(s):  
Particle Size ◽  
Point Source ◽  
Line Source ◽  
Dispersion Coefficient ◽  
Solid Particles ◽  
Gravity Effect ◽  
Dispersion Coefficients ◽  
Source Condition ◽  
Advection Diffusion Equation ◽  
Gravity Settling

Abstract A robust and pragmatic method has been developed and validated to analytically determine dynamic dispersion coefficients for particles flowing in a parallel-plate fracture, in which gravity settling has been considered due to its significant impact on particle flowing behavior. More specifically, a two-dimensional (2D) advection–diffusion equation together with the initial and boundary conditions has been formulated to describe the flow behavior of finite-sized particles on the basis of coupling the Poiseuille flow with vertical settling. Meanwhile, three types of instantaneous source conditions (i.e., point source, uniform line source, and volumetric line source) have been considered. Explicit expressions, which can directly and time-efficiently calculate dynamic dispersion coefficient, have been derived through the moment analysis and the Green’s function method. By performing the simulation based on the random walk particle tracking (RWPT) algorithm, the newly developed model has been verified to determine particle dispersion coefficients agreeing well with those obtained from the RWPT simulations. It is found that the point source is the most sensitive to gravity effect among different source conditions, while the volumetric line source is affected more than the uniform line source. For particle size larger than its critical value, an increased particle size leads to a decreased asymptotical dispersion coefficient for all the source conditions due to the significant gravity effect, while gravity positively affects the dispersion coefficient at early times for the point source condition. In addition, average flow velocity positively affects the dispersion coefficient for all the source conditions, while the associated gravity effect is influenced only at early times for the point source condition.

Optimized Model of Slotted Liners Completion Parameters in Horizontal Well

2012 ◽  
Vol 616-618 ◽  
pp. 804-811
Author(s):  
Quan Tang Fang ◽  
Wei Chen ◽  
Rong Wang
Keyword(s):  
Point Source ◽  
Line Source ◽  
Flow Resistance ◽  
Horizontal Well ◽  
Source Function ◽  
Geometric Model ◽  
Superposition Principle ◽  
Evaluation Index ◽  
Flow Convergence ◽  
Optimized Model

The transient flowing model of slotted liner completion was established by superposition principle based on the geometric model of slotted liners, with the point source function and the single slotting equal to line source, and then the optimized model of slotted liner completion parameter was established with the skin factor of slotted liners completion as evaluation index. After analyzing the parameter sensitivity with cases, the slot density is confirmed as the main reason leading to flow convergence and additional flow resistance. Furthermore, the optimization principles of slotted liners completion of horizontal well are determined. These results are significant in optimizing the slot distribution pattern and parameter allocation.

Transformation from 2-D to 3-D wave propagation for horizontally layered media

Geophysics ◽  
1994 ◽  
Vol 59 (12) ◽  
pp. 1920-1926 ◽  
Author(s):  
Lasse Amundsen ◽  
Arne Reitan
Keyword(s):  
Wave Propagation ◽  
Point Source ◽  
Line Source ◽  
Layered Media ◽  
Cylindrical Symmetry ◽  
Seismic Processing ◽  
Geometric Spreading ◽  
Processing Algorithms ◽  
The Relationship ◽  
D Wave

The relationship between 2-D and 3-D wave propagation in horizontally layered media was first investigated by Dampney (1971). In the last few years the usefulness and feasibility of transforming point‐source responses with 3-D geometric spreading to equivalent line‐source responses with 2-D geometric spreading have been thoroughly discussed (see Helgesen, 1990; Wapenaar et al., 1990, 1992; Herrmann, 1992; Helgesen and Kolb, 1993; Amundsen, 1993). In the case of cylindrical symmetry this transformation constitutes a required preprocessing step for several seismic processing algorithms based on 2-D wave propagation. The work of Dampney (1971) has apparently been missed by the authors discussing the 3-D to 2-D geometric spreading transform.

scholarly journals The Structure of a Stream of Electrons and Ions Drifting and Diffusing in a Gas When Ionization by Collision and Molecular Attachment are Present

1959 ◽  
Vol 12 (2) ◽  
pp. 171 ◽  
Author(s):  
LGH Huxley
Keyword(s):  
Magnetic Field ◽  
Point Source ◽  
Line Source ◽  
Electron Attachment ◽  
Uniform Field ◽  
Electrons And Ions

The theory is developed of the structure of a stream of electrons and ions drifting under the action of a uniform field and diffusing in a gas when either or both ionization by collision and electron attachment are present. The cases considered include a point source and a line source, and in the latter case the influence of a magnetic field is discussed.

APPARENT RESISTIVITY CURVES FOR AN INFINITE LINE SOURCE PARALLEL TO AN INCLINED CONTACT

Geophysics ◽  
1975 ◽  
Vol 40 (4) ◽  
pp. 689-693 ◽  
Author(s):  
Sri Niwas ◽  
S. K. Upadhyay
Keyword(s):  
Point Source ◽  
Line Source ◽  
Apparent Resistivity ◽  
Master Curves ◽  
Harmonic Method ◽  
Resistivity Data ◽  
Infinite Line

Investigations of apparent resistivity due to a point source over an inclined contact have been reported by Aldredge (1937), Unz (1953), Maeda (1955), and Chastenet de Gery and Kunetz (1956). In these investigations either the image or the harmonic method has been utilized. In this note, we propose to solve the same problem as follows: (1) Transform point‐source potential data into line‐source apparent resistivity data. (2) Interpret transformed apparent resistivities by the master curves provided.

Solutions of Heat-Conduction Problem With the Aid of the Inverse Method

1953 ◽  
Vol 20 (4) ◽  
pp. 489-496
Author(s):  
F. S. Weinig
Keyword(s):  
Heat Transfer ◽  
Heat Conduction ◽  
Heat Flow ◽  
Point Source ◽  
Line Source ◽  
Inverse Method ◽  
Plane Surface ◽  
Heat Conduction Problem ◽  
Potential Equation ◽  
Circular Arc

Abstract Using a known solution of the potential equation for heat conduction it is possible to determine boundaries which fulfill the boundary conditions. This idea was applied to the heat flow with parallel streamlines, from a line source and from a point source. From the parallel flow, fins have been derived on a plane surface having circular arc flanks. From the line source, fins axially and radially on a cylindrical surface and from a point source fins on a sphere are obtained. The improvement of the heat transfer has been found in these examples to depend only on the surface direction at the base of the fins.

A comparative seismic hazard study for Azerbaijan Province in Iran

1981 ◽  
Vol 71 (1) ◽  
pp. 335-362
Author(s):  
B. Rowshandel ◽  
S. Nemat-Nasser ◽  
R. B. Corotis
Keyword(s):  
Seismic Hazard ◽  
Point Source ◽  
Ground Motion ◽  
Line Source ◽  
Seismic Source ◽  
Source Model ◽  
Strike Slip ◽  
Area Source ◽  
Area Source Model ◽  
Line Source Model

abstract Different seismic source models are used to estimate regional seismic hazard. Commonly used point, line, and area seismic sources are considered in addition to a new method which is obtained by modifying the line source model to take into account the uncertainty associated with the exact location of the line (i.e., fault). The results are presented in terms of cumulative functions of peak ground acceleration for major sites in the Azerbaijan Province of northwest Iran. Iso-acceleration maps for two different return periods are also developed for each seismic source model and a comparison is made among the results of the models. The point source model is shown to be unrealistic when used to model large shocks (Ms > 6.5), which correspond to long ruptures. The model cannot incorporate the fault length, thus ignoring possible spatial migration of seismicity along the fault. In addition, the actual attenuation of ground motion departs considerably from that associated with point source assumption. The conventional line source model, while providing a good representation of vertical strike-slip faults, cannot accurately model the seismicity in other cases, such as reverse faults in general, and thrust (low angle reverse) faults in particular. Epicenters for these latter cases do not lie along a line, as they do in case of vertical strike-slip faults. The area source model is used for those cases where the distribution of earthquake epicenters in a region does not follow any identifiable geological fault pattern. The spatial migration of seismicity along an active fault during a given exposure time is of vital importance in seismic hazard analysis. An analysis based on an area source model corresponds to assuming this migration will be equal in all directions. The theory of plate tectonics, however, suggests an elongated narrow zone corresponding to each fault. A fault line model is developed which exhibits less sensitivity of near-field ground motion to precise fault location than the line source model. This model is referred to as the strip source model. According to this model, the seismicity on a fault is spatially distributed in a long and narrow zone along the margins of the corresponding plates or microplates, and decreases with distance from the fault on either side. It is believed that this kind of modeling closely represents the seismicity corresponding to interplate earthquakes, especially when the type of faulting is thrust. Uncertainties due to the location and orientation of faults will be considerable, particularly for the buried faults, and these uncertainties can be incorporated in the strip source model.

The Location of Building Defects Using Structural Intensity

1996 ◽  
Vol 3 (4) ◽  
pp. 217-231
Author(s):  
Robert J.M. Craik ◽  
R. Wilson ◽  
R. Ming
Keyword(s):  
Point Source ◽  
Line Source ◽  
Power Flow ◽  
Concrete Block ◽  
Background Intensity ◽  
Concrete Floor ◽  
Structural Intensity ◽  
Residual Intensity ◽  
Block Wall

Many defects in the construction of buildings act as transmission paths across which unwanted sound can travel. The resulting increase in power flow can be measured using structural intensity techniques and the location of the source found from the intersection of two or more intensity vectors. This technique can be used to locate a source (or sometimes a sink) when the intensity being measured is above the residual or background intensity. Some applications of this technique are discussed and it is used to locate a point source on a concrete floor and a line source exciting a concrete block wall. The technique was found to work well for a point source but was less reliable for a line source. This was partly because a line source is less well spatially defined and partly because the damping of the wall was low, resulting in a high residual intensity.

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