HPLANE Geophysical EM response of perfectly - Wiki
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1. computed only after the Update parameters button is pressed The next seven text fields define profile parameters PA Profile azimuth degrees real 90 perpendicular to half plane PD Profile dip degrees real 90 vertical downwards X0 Start x position m real the distance to the half plane YO Start y position m real merely as a reference value ZO Start z position m real used for AEM and borehole systems PR _ total length of the profile m real DP step between measurement points m real The last five text fields define source and receiver parameters LS Loop dipole spacing m real DH Transmitter receiver dipole height difference m real TX Transmitter x position m real for fixed VMD source only TY Transmitter y position m real for fixed VMD source only TZ Transmitter z position m real for fixed VMD source only 3 Few notes on model and system parameters Depth DE is given a positive value although z axis is positive upwards The slide widget restricts the depth between 0 01xLS and 5xLS Dip DD is taken from the positive x axis East towards positive z axis downwards and the slide widget restricts it between 90 and 90 degrees If DD 90 the half plane is vertical downwards Profile azimuth AS is taken from the positive y axis towards positive x axis and it can vary freely normally 180 lt AS lt 180 If AS 90 the profile is perpendicular to2. In the fixed VMD system the transmitter position is fixed and the receiver moves along the profile The measurements are placed at the receiver position and the field components are computed either with respect to the profile or with respect to the xyz coordinate system VMD system Profile of measurement points Tx Rx ra a adb r teceiver are moved together HMD system ee so that they have a fixed loop spacing L Pied NINES system The source is fixed and the Tx Rx teceiver moves along the profile e Earth s surface Figure 2 Schematic view of the three different measurement systems Installing the program The distribution file HPLANE ZIP contains the stand alone executable HPLANE EXE short description file LREADME TXT GNU GPL terms _COPYING txt and the user s manual HPLANE_MANU PDF in PDF format The SOURCE sub folder contains the Fortran90 source code To install the program unzip the distribution file somewhere on the hard disk and a new folder appears Additionally create a shortcut on the desktop but make sure that the start up folder is the same as the program directory Starting up On startup the program reads its input parameters for the model and system from the HPLANE INP file and the graph parameters from the HPLANE DIS file If these files do not exist default parameters are used and the files are created automatically The program then computes the response and builds up the u
3. normalization is made using the same Hpz component as in VMD system This means that Hp Hpz is computed at the distance of loop spacing and elevation difference LS and DH i e not at rowing receiver locations For fixed VMD system the configuration mode in line vs broadside defines the field components which are either related to the profile direction as in VMD and HMD systems or to the true xyz coordinates File formats Graph parameter file HPLANE DIS Editing the HPLANE DIS file allows translating the graphs into another language by Note that the format of the HPLANE DIS file must be preserved If the format of the file becomes invalid one should delete the file and a new one with default parameter values will be generated automatically the next time the program is started The file format is shown below 0 01 5 00 0 01 Os 18 0 Hee 32 28 24 22 20 1 I 1 1 350 300 0 55 0 85 0 80 1000 145 25 6 Normalized magnetic field components VMD measurement system HMD measurement system Fixed VMD meas system In line configuration Broadside configuration Profile components XYZ components Distance Response VMD VMD Hsz Hpz VMD HMD Hsx Hpz VMD HMD Hsy Hpz HMD HMD Hsx Hpx HMD VMD Hsz Hpx HMD VMD Hsy Hpx The 1 st line defines the minimum maximum and step values used in the scale widget that defines the normalized depth D L Similarly the 2 nd line defines
4. start m e HO 0 79577E 07A m Step m Tx Rx parameters Loop spacing m Elev diff m Response 3D view point Horiz rotation a 70 Vert rotation ET 30 Rel distance 4 200 Distance m VMD HMD Hsx Hpz VMD HMD Hsy Hbz EM half plane v 1 4 by MTP c 2014 Grant amp West 1967 E e o o VMD VMD He H 3 Figure 3 Screendump of the HPLANE program 2 Menu items The main window of the HPLANE application contains three menus The File menu contains the nine items Open model Open an existing model file Save model Save the model into a file Save results Save results description response into a file aaa Read in new graph parameters from a DIS file ea in m Save the graph in Adobe s Postscript format A Ac EPS Save the graph in Adobe s Encapsulated Postscript format Save graph as PDF Save the graph in Adobe s Acrobat PDF format Save graph as WMF Save the graph in Windows metafile format Save graph as GIF Save the graph in Graphic Image File format Save graph as PNG Save the graph in Portaple Network Graphics format Selecting any of these menu options brings up a standard Windows file selection dialog that can be used to select an existing file or provide a name and location for new output file Model and result files are text files The graphs are saved in landscape A4 size as they appear on the screen The
5. the half plane and points towards East Profile dip PD is taken from the horizontal plane and it can vary freely normally 90 lt PD lt 90 If PD 90 the profile is vertical downwards DH is the elevation difference of the transmitter dipole from the receiver If DH gt 0 the transmitter locates higher than the receiver if the profile is horizontal This parameter should be used only when modeling some air borne or cross borehole measurement systems In VMD and HMD systems the direction of the source dipole axes and the computed field components are related to the profile direction HMD is directed along the profile and VMD is directed perpendicular to the profile Thus VMD is vertical magnetic dipole and HMD is horizontal magnetic dipole only when the profile is horizontal PD 0 If the profile is dipping up or down the VMD source will have horizontal component and HMD will have vertical component that depend on profile azimuth and dip angle The user must be careful when dealing with oblique and dipping profiles since the orientation of the response components can become unclear In general Hsx is the axial component Hsz is perpendicular to the axial component and PD and to the profile direction SA and Hsy is horizontal and perpendicular to the other two components follow the right hand rule This means that the field components coincide with the xyz coordinate system only when SA 90 and PD 0 in which case the pro
6. HPLANE Geophysical EM response of perfectly conducting half plane User s guide to version 1 4 Markku Pirttij rvi 2014 University of Oulu E mail markku pirttijarvi at gmail com Introduction The HPLANE program computes the EM profile response of a perfectly conducting half plane in free space for various geophysical dipole dipole measurement systems The half plane is used to model a thin highly conductive target in resistive surroundings The computational method is based on the analytical solution presented in the classic book of F S Grant and G F West 1967 Interpretation theory in applied geophysics HPLANE can be used for educational purposes and as an approximate interpretation tool for geophysical EM measurements HPLANE is a 32 bit program that can be run on a PC with 32 bit or 64 bit Windows operating system and a graphics display with a resolution at least 1024x768 pixels Memory requirements and processor speed and are not critical factors since the program uses dynamic memory allocation and the analytical EM solution allows very fast computation even on slow computers The HPLANE program has a simple graphical user interface GUI that can be used to change the parameter values to handle file input and output and to visualize the EM response and the model Figure shows a cross section of a dipping half plane model The half plane is considered to be semi infinite which means that it has infinite strike le
7. Hplane menu contains four sub menus Source system Source is moving VMD or HMD or fixed VMD Configuration gt Loop configuration is either in line or broadside Response scaling gt Response as plain ratio per cents or per million ppm Distance scaling P X axis is normalized with loop spacing or not The Exit menu has two items Restart wide norm is used to close and restart the whole GUI using a screen aspect ratio that suites either old 4 3 displays or widescreen displays eg 16 10 When changing from normal to widescreen mode the program asks for an aspect ratio value relative Value between 0 7 0 8 is good for most widescreens OK to exit is used to confirm the exit operation On exit the current model and results are automatically saved in the HPLANE INP file Errors that are encountered before the GUI starts up are reported on the console window Run time errors arising from illegal parameter values are displayed on the screen Program controls The two slide controls at the top of the left pane of the HPLANE window define DE Depth to the top of the half plane normalized with loop spacing real DA Dip angle degrees 90 vertical half plane real The Change component button is used to change the EM response components shown in the graph When the slide widgets discussed above are applied the response is computed automatically When the text fields discussed below are edited the EM response is
8. e compiled and run for example on Mac and Linux without modifications See the comments regarding parameter IPLA in the source code If you find the computed results erroneous or if you have suggestions for improvements please inform me Note that although the profile can pass through the half plane the source and the receiver can never coincide with the half plane This case is handled inside the computational code by adding a small value to the radial distances if they should become zero Be warned that this can produce artifacts to the computed results especially when the profile coincides with the top of the half plane Copyright and license Copyright 2014 Markku Pirttijarvi HPLANE is free software you can redistribute it and or modify it under the terms of the GNU General Public License as published by the Free Software Foundation either version 3 of the License or at your option any later version HPLANE is distributed in the hope that it will be useful but WITHOUT ANY WARRANTY without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE See the GNU General Public License for more details You should have received a copy of the GNU General Public License along with HPLANE If not see lt http www gnu org licenses gt 10
9. file is horizontal parallel to x axis and perpendicular to the half plane The Hsx Hpx response component of in line HMD HMD system represents co axial system and broadside HMD HMD represents co planar system In VMD and HMD systems the measurements are positioned at the mid point between the Tx Rx pair Note however that the results of the output file are presented using only the profile distance not the actual xyz coordinates Although in free space the VMD and HMD systems obey reciprocity the source 4 is normally behind the transmitter in in line configuration and left to the receiver in broadside configuration The initial starting positions of the source and receiver are shown in the 3 D model view using an open circle and a plus sign respectively Loop spacing values less than zero LS lt 0 m are used to interchange the positions of the source and the receiver This option affects only the horizontal response components of the VMD and HMD systems For VMD source systems the normalization is made using the free space vertical magnetic field Hp Hpz at the distance of loop spacing and the columns are the vertical field Hsz Hp the field along the profile Hsx Hp and the perpendicular component Hsy Hp For HMD system the normalizing field is the horizontal magnetic field Hp Hpx and the columns are the axial field Hsx Hp vertical field Hsz Hp and the remaining perpendicular component Hsy Hp In fixed VMD system the
10. ines for the Gnuplot plotting program The EM response is located at the end of the output data file The first column is the profile coordinate distance from the beginning of the profile Columns 2 4 show the normalized EM response Columns 5 7 are the actual secondary field components the order of the components is the same as in columns 2 4 The eighth column contains the constant normalizing field component Hp Hpz or Hpx Note that the dipole moment of the source is always 1 0 Am Reference Grant F S amp West G F 1967 Interpretation theory in applied geophysics McGraw Hill New York p 520 528 Additional information Originally I made the HPLANE program at the University of Oulu in October 2001 when I worked as a researcher funded by a grant from Outokumpu Foundation addressed to Prof Sven Erik Hjelt Further modifications to the software were made in September 2002 and March 2003 after I had received a grant from T nning Foundation Version 1 4 is the first release under GNU General Public License GPL accompanied by the Fortran90 source code demonstrating the use of DISLIN graphics library in building graphical user interfaces HPLANE is written in Fortran 90 style using Intel Visual Fortran 11 4 The graphical user interface is based on the DISLIN graphics library version 10 2 by Helmut Michels http www dislin de Since DISLIN library is available on other operating system the HPLANE program could b
11. lot area is 2970x2100 pixels landscape A4 The last parameter defines the screen aspect ratio for widescreen mode e The first parameter on the 6 th line defines the size in pixels of the square area reserved for the 3 D model The position of the model area is always next to the lower right corner of the response graph The remaining three parameters define horizontal and vertical viewing angles and a perspective viewing distance for the 3 D model view e The following lines define various text items of the graph max 40 characters These are the main title of the graph 60 chars the system configuration in the description text 60 chars the axis titles of the graph and legend texts used for the different response components of the graph Depending on the response and distance scaling defined in Hplane menu the units are automatically added after the axis titles eg or ppm for the y axis and S L or m for the x axis Note that xyz suffices are used for the response components although this may not be the case if the profile is not parallel to x axis Result file DAT The following text illustrates the output file DAT format HPLANE model file 20 00 60 00 90 00 0 00 200 00 0 00 0 00 400 00 10 00 100 00 0 00 1 1 0 0 Description Depth to the top DE 20 00 Dip angle DA 60 00 Profile azimuth PA 90 00 Profile dip PD 0 00 Profile x start X0 200 00 Profile y start YO 0 00 Pr
12. ngth and depth extent Although the half plane is also infinitesimally thin it is a perfect conductor which means that it produces the inductive limit EM response Since the half plane is an ideal conductor and it locates in free space the EM response has the in phase real component only Infinite depth extent and strike length Z Figure 1 Cross section of the half plane model Important The coordinate system is such that the x axis points left East y axis points up North and z axis points up Although the half plane is in free space which allows full freedom for system orientation the model assumes that the plane z 0 represents earth s surface and the top edge of the half plane is always below the y axis x 0 Figure 2 illustrates the three main types of measurement systems used in HPLANE program The transmitter Tx is either a vertical VMD or a horizontal HMD magnetic dipole The receiver Rx measures the same component as the source and the other two orthogonal response components VMD and HMD systems are profiling methods that use a fixed spacing between the Tx Rx pair These methods are operated either in an in line as in Figure 2 or in a broadside fashion In in line configuration the fictional line connecting Tx and Rx is coincident with the profile traverse In a broadside system the Tx Rx line is perpendicular to the profile The measurements are positioned at the mid point between the 7x Rx pair
13. ofile z start Z0 0 00 Profile length PR 400 00 Point spacing DR 10 00 Loop spacing LS 100 00 Height difference DH 0 00 easurement system VMD VMD IS 1 eas configuration In line IC 1 Transmitter start and end positions X position TX 250 00 150 00 Y position TY 0 00 0 00 Z position TZ 0 00 0 00 Receiver start and end positions X position RX 150 00 250 00 Y position RY 0 00 0 00 Z position RZ 0 00 0 00 Dist Hsz Hp Hsx Hp Hsy Hp Hsz Hsx Hsy Hp 0 0 0 5118E 02 0 7365E 03 0 5768E 10 0 407E 09 0 586E 10 0 459E 17 0 7958E 07 10 0 0 5974E 02 0 7533E 03 0 6353E 10 0 475E 09 0 599E 10 0 505E 17 0 7958E 07 20 0 0 7031E 02 0 7453E 03 0 6961E 10 0 559E 09 0 593E 10 0 554E 17 0 7958E 07 BEG esx Note that the output data file contains a copy of the model file INP The format of the model file should become clear from the example above since the description text defines the parameters in the same order as they appear in the input file The four last parameters in the model file define the numerical integer values of the measurement system l VMD 2 HMD 3 fixed VMD configuration 1 in line or profile components 2 broadside or xyz components response scaling O plain ratio 1 2 ppm and distance scaling O no scaling x axis is normalized with loop spacing For historical reasons the character is used to make comment l
14. ser interface shown in Figure 3 The EM response is plotted in the graph area along with a 3 D view of the model and a description of the model parameters The model and system parameters are changed using the program controls on the left side of the HPLANE window and the items in the Hplane menu The items in the File menu are used to save and read model and system setting in from a INP file save computation results in DAT file and to save the current graph into graphics file PS EPS PDF WMF GIF PNG The 3 D model view depicts the top edge of the half plane and the location of the profile using solid lines The surface projection of the half plane is drawn with dashed line The locations where the half plane cuts the sides of the 3 D view box are shown using a dotted line If the profile is above the surface ZZ gt 0 m the surface plane is drawn using dotted lines as well The small circle and the cross depict the location of the transmitter and receiver respectively Note that the 3 D model view uses normalized coordinates X L Y L Z L File Hplane Exit Normalized depth Emy Dip angle deg ET Chi Update parameters Profile parameters Azimuth deg Dip angle deg i LS 100 0m PA 90 0deg PD 0 0deg X start m X0 200 0m Y0 0 0m Z0 0 0m Y start m PR 400 0m DR 10 0m DH 0 0m VMD measurement system In line configuration DB 20 0m D L 0 20 DA 60 0deg Z
15. the minimum maximum and step value used in the scale widget of the dip angle Note that depth must be greater than 0 and dip angle must be between 90 and 270 degrees The 3 rd line defines five character heights The first one is used for the main title and the graph axis titles the second height is used for the axis labels the third height is used for the plot legend text the fourth height is used for the model description text and the last height is used for the axis labels in the 3 D model view The 4 th line defines parameters that modify the graph appearance The first one can be used to include 1 or exclude 0 the model information text to from the top right corner of the page The second one can be used to include 1 or to exclude 0 the model view to from the bottom right corner of the page The third parameter is used to define the corner where the legend text is positioned Values 1 4 put the legend in SW SE NE or NW corner of the page outside the graph Values 5 8 put the legend in the SW SE NE or NW corner inside the graph The default values are 1 1 7 The fourth parameter defines whether or not widescreen mode is active 0 1 The 5 th line defines the x horizontal and y vertical distance of the origin of the main graph in pixels from the bottom left corner of the page and the length of the x and y axes relative to the size of the remaining origin shifted width and height of the plot area The total size of the p
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