GTOSS “Getting Started”
Contents
1. needed to define the dynamical system and thus commence executing the simulation Failing to find an INGOSS file in its local directory GTOSS next looks for a file named RTPATH this file would then be assumed to provide information about where GTOSS can find the intended INGOSS file thus RTPATH is a directory re direction file Under all conditions failure to identify and open a requested file name will precipitate a Fortran file open failure system warning message and a run time abort The format and contents of the INGOSS file is explicitly specified within the GTOSS documentation Furthermore a skeleton version of this file is included within the GTOSS delivery found here A__ RUN GRUNS GSKL_vH12 This GSKL file is rather voluminous as it contains EVERY system configuration data item as well as execution options offered by ALL features of GTOSS thus it can be daunting at first sight A good way to deal with this complexity is to build on existing INGOSS files that have already been setup to define typical situations with appropriate execution option features For instance within the main delivery directory folder there can be found a set of 36 INGOSS files located at A__ RUN GRUNS GRUNOO thru GRUN35 These correspond to a myriad of tethered dynamics situations These files are included as part of the exhaustive array of executions that GTOSS must perform to pass auto validation BUT2. PP as opposed to writing a whole new standalone PP program to access the RDB adding a clone can often be done in 10 or 15 minutes for those who are familiar with this For instance suppose a user wants to create a column delimited data file that contains a particularly convenient subset of data the user would either clone and modify an existing output option that was similar to what was desired or clone and flesh out a stubb In all cases the user would presume upon the PP to actually take care of details of accessing the analytical variables of the RDB rather than attempting to deal directly with the schema used by GTOSS to stash this data in the RDB VTOSS This is not a PP in the above sense however it is a program that can be run to compare data that has been previously output in a special validation data format by the post processor UTOSS in such a way as to allow validation ie comparison between a Reference set of data usually generated from a previously verified version of GTOSS and the identical data items as generated by the new version of GTOSS that is a candidate for verification Getting Started with GTOSS User Defined Input to GTOSS When GTOSS wakes up during execution it first looks around the directory or folder in which it launched for a file with the explicit name INGOSS note this must be upper case as case counts in Unix GTOSS views this file as containing all the information
3. code so as to render an executable but dysfunctional GTOSS application Building GTOSS 1 At this point it is assumed that the user has created a directory folder called say myGTOSS and contained directly under this directory are all the intact sub directories of the GTOSS code delivery see section above on Delivery Files for what the source contents of this directory should look like 2 The various Unix Script files should be removed from their sub directory and now also reside as individual files directly under the same user directory myGTOSS 3 Open a Unix Linux terminal shell and navigate until the shell s current working directory is in fact myGTOSS Confirm this by using the pwd command 10 Getting Started with GTOSS 4 Now attempt a GTOSS compile and link by invoking the GTOSS make file using the command make f MakeGTOSS 5 This should start a compilation as witnessed by a march of lines each containing the list of compiler options being used the GTOSS sub routine name being compiled such a GTOSS GTOSUB etc etc If you have arrived at this point then just let the process proceed until completion However it is possible that the response you get to invoking the make file may be a system diagnostic such as no such directory or file found If this is the case then barring an error in navigating to myGTOSS the make file may not be recogn
4. functionally comfortable with Unix or Linux While this delivery was developed under Ubuntu a particular Linux distribution it should be fairly applicable to all such variants of Unix for example the Darwin Unix variant underlying the Mac OS X implementation The Target Platform This delivery was specifically developed in the context of Ubuntu running on an Intel PC machine and arrived thereto from a previous implementation on the Darwin Unix kernel running on a PowerPC Mac While all that is really essential to setting up GTOSS is access to a Fortran 95 compiler on your platform cross platform cross compiler porting can present a multitude of small but surmountable nuisances and roadblocks for bringing up GTOSS under other Ubuntu platforms such should be virtually non existent A word of warning Some Linux Unix Platforms may take liberties with the text case of directory and file names during the process of porting and reconstitution of source code file structures In particular the OS may set all UPPER case names to Lower case this perversity can go deep into the directory structure This of course can wreak havoc upon the Unix make file Fortran compiling and directory access protocols Since it does not touch text within a file one can consult the make files to gain an understanding of how the naming convention should look The GTOSS delivery files have bee zipped within a single delivery folder as a means o
5. in addition they also represent a wealth of examples that can be used as starting points for building new situation INGOSS files These runs are generally easier to deal with because they have been stripped of many of the options that are extraneous to a particular application and feature a narrowed sub set of geometry configuration data Of course one can always start with the full content GSKL file and systematically delete non applicable items however even for a knowledgeable GTOSS user this can become tedious thus said users usually resort to this approach somewhat infrequently The post processors behave in a totally parallel fashion to GTOSS regarding their attempt to read input They too look for a primary input file and failing to find same then turn to a possible alternate input path re direction namely that same file RTPATH that GTOSS would use thus RTPATH defines input re direction to ALL GTOSS application The only difference is in the name of the input files that each program ultimately reads these designations are shown below along with their locations in the delivery file set DTOSS reads INDOSS see A __ RUN DRUNS DSKLv04 DRUNOO DRUN35 CTOSS reads INCOSS see A __ RUN CRUNS CSKLv04 CRUN04 misc selec UTOSS reads INUOSS see A __ RUN URUNS USKLv03 URUNOO URUN35 VTOSS reads INVOSS see A __ RUN VRUNS VSKLv02 VAFOWF1 misc Getting Started with GTOSS Delivery Files an
6. the g95 GNU website names a couple of candidate package installers for this An appropriate Internet search of identifying names of the missing library module will usually turn up information leading to the identity of the missing library and information about how to download and install same you are likely not the first to have encountered this failure 11 Getting Started with GTOSS Building Post Processors In a manner completely parallel to the GTOSS build procedure described above the rest of the GTOSS Post Processor executable programs can be built Instead of using MakeGTOSS they would employ make f MakeDTOSS make f MakeCTOSS make f MakeUTOSS make f MakeVTOSS Resulting Application Programs A successful make of the GTOSS application programs will yield the following executable files GTOSSvH12 DTOSSvH12 CTOSSvH12 UTOSSvH12 VTOSSvH12 These will all reside in your directory called myGTOSS Make file Options and Using the Other Script Files The first thing to note about all the delivered make files is the cleanwell feature For instance many times a change is made in a header ie include file that will affect ALL or most of the other sub routines of GTOSS etc In this case re running a make file build will not precipitate a re compile of all of the subroutines which say is necessary for the include file change to be properly felt through all code This is due to the way in whi
7. COSS files as shown below Your_first_GTOSS_Run a Directory folder INGOSS SE Lib GTOSS Sample Run input file INCOSS SE Lib CTOSS Post Processor input file Move these two files to your directory SE_Run and rename them to simply INGOSS and INCOSS At this point your test run folder should look like this SE_Run INGOSS INCOSS GTOSSvH12 CTOSSvH12 Now execute GTOSS by opening a Terminal shell and navigating current working directory to SE_Run and entering the command GTOSSvH12 15 Getting Started with GTOSS This should start output data appearing in the Terminal shell this output will consist of an initial set of run setup information followed by a sequential synopsis of the time history of the GTOSS solution as it unfolds The run terminates at 100 000 sec and you should see a GTOSS Normal termination enunciation You can now examine the contents of SE_Run to see what has transpired In your test run directory you should see the OUTQUIK file which you can open and examine with a text editor and also the set of RDB files Next execute the Post Processor CTOSS in a similar fashion to what you did to execute GTOSS just use the same Terminal shell since its current working directory is already set to SE_Run After running CTOSS you should immediately get an enunciation of Normal CTOSS termination At this point a new set of files will have appeared in SE_Run these will be
8. GTOSS Getting Started GTOSS Version H12 1 Release for Ubuntu Distribution of Linux likely compatible with all Linux and Unix variants Oct 2008 Developed By David D Lang Associates Seattle WA Originally for NASA Johnson amp Marshall Space Flight Centers Then On going for Various Industry Advocates amp Supporters ACKNOWLEDGEMENT The author of GTOSS would like to acknowledge Keith Curtis and Brad Edwards for their encouragement and support in making this release of GTOSS available to the Space Elevator Community Table of Contents OVERVIEW What is GTOSS sssesssoeessoecsssecsssoesssoesssocsssoesssoe J The GTOSS A p pli Cations soc cvccsictescccsctsccvvecveseseisessscecesaccenssvesseosseene How GTOSS W OFKS sscscesssncssssvccvesssesiavensiss vessiacsscveoveaseoknseatessvecsse4 User Defined Input to GTOSS csssssssssssssssssssssssscsssssssssseee O Delivery Files and Suggested Directory Structure se00008 7 Pris CalliniG Ge VOSS osecisssascasvacssssascseucdisesastasausaersdseesvacaenvavesavesosestvevascsdeenesguacsveuedatennssnsensss 9 Th Target PlAthor riisysciscccscessstehctscesceces denackesossdeacoduescaoavetcesssdusachequacsecratssnchsovccsssessoens 9 Installing the Fortran Compiler ssesssesssoesssosssocessessoosssoessoosssosesoesssoessoesssosssosssoesssse 9 C Pre Processin t enimere ra e a r R Ye pee th 10 B ilding GT OSS sesssessacscscsvusteasesacvesase
9. a place where nothing seems to work properly and what s more there is little to go on as to what is wrong when you enter this wonderful world of the make file madness Running GTOSS How To Do It and What Happens The preferred way to run GTOSS is to place both a copy of the GTOSS executable AND the INGOSS file in the same directory Folder and execute GTOSS there you can just clone a copy GTOSS to this directory containing the run ingredients After execution this folder then will contain the following note you start by putting into the directory the oreen files and after execution the red files will have shown up in the directory GTOSS which you put there INGOSS which you put there and serves as a run s concise definition for later ref RDB files created by GTOSS and which can be Post Processed for results display GERROR created by GTOSS a text file with info about any errors that occurred OUTQUIK created by GTOSS a text file time history synopsis that is written as the simulation unfolds to provide the user a quick look at how the simulation progressed it can also be examined during execution also there are a number of different pageformat definitions available for this synopsis file pertaining to various generic usages of GTOSS page selection is made via a parameter in the INGOSS file Note output to a Unix terminal shell can also be specified as a means of monitoring execution thr
10. ch the GNU make utility manages the selection of which files need to be re compiled at any particular time that rule being if a source file has changed then re compile it The problem is that this decision is triggered only by explicit changes to a source file and is oblivious to changes in header files Thus the user MUST force a full recompile This can be done by using an argument in the make file that will simply delete the associated o files related to the make So simply execute make f MakeGTOSS cleanwell There will be no terminal response this will not precipitate a compile BUT you will find that the o files will now be gone Next then just re execute the make command except with the cleanwell argument deleted This will force re compilation of all the related modules This same modus operandi will apply to ALL the Post Processor make files 12 Getting Started with GTOSS If ALL the o files need to be deleted and a completely clean new build of GTOSS and all the PP s need to be made use the Scripts ALL _cleanwell followed by MakeALL These would be invoked from the terminal via the commands ALL_cleanwell followed by MakeALL These make files adhere closely to the standard GNU make utility definitions One can fairly well determine what is going on in the make files by examining their contents however before modifying them make sure to save a copy as it is easy to enter
11. cripts shown as below MakeGTOSS GNU make file to build GTOSS MakeDTOSS GNU make file to build DTOSS MakeCTOSS GNU make file to build CTOSS MakeUTOSS GNU make file to build UTOSS MakeVTOSS GNU make file to build VTOSS MakeALL Linux Script file to build all the GTOSS programs ALL_cleanwell Linux Script file to delete all GTOSS o files RTPATH Re direction file for GTOSS inputs optional usage only case convert script Contains script to convert Dir File names gt upper case if needed verify GTOSSv12 INVOSS Input to VTOSS INVOSS used to verify GTOSSvH12 1 OUTDISvH121 Contains Output data files from DTOSS for the 36 ref runs VERIFYVH121 Contains output from UTOSS for GTOSS verification w VTOSS SE_ Lib_Run_Example INGOSS SE Lib GTOSS Sample Run input file INCOSS SE Lib CTOSS Post Processor input file Your First GTOSS run INGOSS SE Lib GTOSS input file to create a Space Elevator example run INCOSS SE Lib CTOSS Post processing input to create graph able results SE Dynamics Exploration Runs Directories containing definitions of 35 different SE dynamics explorations Getting Started with GTOSS Installing GTOSS Due to the idiosyncrasies of various computer platforms and operating systems the best way to acquire GTOSS is to simply compile an executable version of the program from the Source code itself It is assumed that the user is at least
12. d Suggested Directory Structure The software delivery consists of five distinct elements 1 This Getting Started document 2 Directory containing GTOSS User Reference Document set 10 pdf files 3 Directory containing getting started first example GTOSS run for users 4 Directory containing Extensive GTOSS Space Elevator Dynamics Explorations 5 Directory containing Source Code Directories and sub directories Unix Linux Scripts for make files and other useful operations Input Text File Directories for reference and GTOSS verification NOTE The source code delivery structure is chosen specifically so as to expedite the creation of GTOSS using delivered make files the hierarchical directory order of this delivery is critical because source code references to include files use path names that assume this specific source code directory structure so to compile as a turn key operation with no need to touch source code requires the suggested source code structure below So one would start by creating a directory say myGTOSS and deposit delivery conten into that directory this would result in a directory structure containing at a minimum the files and directories shown below myGTOSS the directory you create to contain all the delivery files A_HDR source for GTOSS include files amp F95 modules amp data classes A_GOSS source for main program host for GTOSS A_TOSS so
13. e then 1 The user can open a terminal and set its current working directory to the subject folder AND 2 Enters a command to execute GTOSS directly Note 1 In the first example these steps are accomplished automatically for you by the simple act of double clicking the executable GTOSS the 2 scheme is much less convenient but works fine to accomplish the end result Note 2 GTOSS is executed in the later case from the terminal by entering the command GTOSS or whatever the name of the GTOSS application happens to be The GTOSS user can specify Terminal output formats from a selection of output options these options are noted in and specified via a data item in the INGOSS file also discussed in the Official documentation In addition during a run GTOSS writes to the OUTQUIK file discussed previously in this document Error Reports Two kinds of errors can appear System Fortran runtime errors and GTOSS perceived errors Some GTOSS errors are reported via the Terminal while others are reported via the GERROR file that always attends a GTOSS execution If any kind of problem 14 Getting Started with GTOSS develops it is wise to check the GERROR file for the case of Post Processing the DERROR CERROR file etc A large number of GTOSS subroutines can encounter and will report problems and then execute a Fortran STOP command such Stop commands are almost always accompanied by the identification of the ro
14. f hopefully avoiding this Installing the Fortran Compiler This delivery was compiled under the GNU Open Source Fortran called g95 another variant of this Fortran called gFortran is also available as free ware The g95 compiler was found to present no bugs in running through the 60 000 lines of code that exercised a great many of the advanced features of the Fortran 95 language specifications complex data classes pointers etc To get started visit the g95 web site or go through GNU directly and locate the g95 delivery downloads that pertain to your specific OS and CPU platform type The installation of g95 can be somewhat problematic if you fail to install ALL the support packages needed or if Ubuntu is missing tools that g95 needs but were not installed on your original Ubuntu implementation If this is the case you will likely not know it until Getting Started with GTOSS you attempt your first executable build see next section The g95 download site strongly recommends utilizing a package installer such as apt get or Synaptic Package Manager as opposed to attempting to figure out what is needed and performing a manual install Confirm compiler operation by issuing the command g95 in a Unix terminal shell If the compiler has been properly installed and its location ie search paths to it has been made known to the system then this command should elicit a response from the compiler identify
15. f the phenomenon in order to be vigilant in this regard Perusal of the input skeleton files included in the delivery and that contain the input data item identification numbers for every input item known to GTOSS etc can function admirably as a complete and concise GTOSS features expose actually to a fault since EVERYTHING GTOSS does is represented there You may not like the GTOSS user interface admittedly it is a bit dated since GTOSS was conceived and written initially before bit mapped monitors when all user interaction was via text line output with no GUI s but realize that the input specification problem of defining to the simulation code an arbitrary number of bodies connected in arbitrary fashion by an arbitrary number of tethers is not a trivial user interface or data specification problem That admitted GTOSS has been used by MANY scientific and engineering organizations in the hands of highly skilled and experienced engineers and scientists and has passed muster as well as passed simulation reconciliation testing against an assortment of other recognized tether dynamic codes The point here is that one MUST read at least the basic documentation describing what GTOSS does and how it does it then they will be in a much better position to assess the nature of difficulties that are encountered and look first to themselves for the answer rather than blame a code that is likely almost as old o
16. files containing column delimited data results from the simulation Now examine the CTOSS input file INCOSS by opening it in a text editor Each of the 7 output file invocation blocks will start by specifying a CTOSS format Look in the Quick Ref Use manual under CTOSS formats or the CTOSS User manual to see details about what the columns of data represent Finally with your favorite engineering graphing program see if you can open and plot some variables that look to be interesting If you do this you will have successfully executed your first GTOSS simulation of the Space Elevator and derived actual useful practical results Last examine the INGOSS file and try some variations in parameters for example Shorten or lengthen the run time or Output data less frequently or more frequently or Change the libration perturbation Note since the run is configured to perturb the SE from a stable vertical configuration by a linearly distributed velocity perturbation profile along its length that culminates at a peak value of 2000 fps at the ballast ie SE upper body mass search the INGOSS file for the number 2000 to find how that perturbation was specified then modify it to say 4000 Making More Advanced Space Elevator Explorations Included in the GTOSS delivery SE Dynamics Exploration Runs are a number of individual directories representing a total of 35 different SE runs These runs can be conducted in exact
17. gnificant experience in advanced dynamics that said it does give one an appreciation and overview of resides within GTOSS The source code files contained in the directory A_HDR are also vital to understanding the definition of results data made available to the user via DTOSS and CTOSS in particular the header files EQU_HOST i Host simulation TOSS Object 1 the Ref Point data items COM_RPS i the State of the TOSS Ref Point and items related to a wide scope COM_ALL i Universal parameters used by all EQU_OBJI i Non Body specific data items related to ALL TOSS Bodies EQU_TOSS i data items related to ALL TOSS In the files below disregard the lower case r and I preceding variable names the uppercase characters are the ones being defined and used in actual code Finite_Solution_Data_Structure i Finite Tether Object data items TOSS_Object_Data_Structure i TOSS Body Object data items 19 Getting Started with GTOSS Interface Control Document Many concepts which the other documentation has assumed to be common knowledge to the user are in fact introduced and defined only in this manual DTOSS Reference Manual CTOSS Reference Manual UTOSS Reference Manual RTOSS Reference Manual Skim read these for indoctrination only VTOSS Reference Manual Useful read if you intend to validate your installation or do user modifications to GTOSS 20
18. has completed Thus were the desired output variables necessarily specified before a run to be dumped during the run and if after the run the user wished other variables could be examined the run would have to be repeated clearly a significant waste of lapsed time as well as CPU resources Since complex tether simulations often take hours and even days to complete it represents a significant use of resources to re do a run The RDB by capturing all the data from a run becomes then a way to preserve this resource investment The definition of this data can be related to the analytical variables defined in the GTOSS equations document More information can be found about this in the RDB ie RTOSS User manual The POST PROCESSORS PP s All these programs that provide access to the RDB in behalf of the user are called Post processors PP s There is a large number of user friendly options already available within each of these PP s The PP output options typically are data synopses that are applicable to aspects of specific types simulation explorations and other useful general Getting Started with GTOSS aggregations of data pertaining to dynamics interpretations The definitions of these options are found in the respective PP user manuals as well as the Quick Ref manual The specific Post Processor Programs provided are DTOSS generates a text file layout format friendly to user visual perusal CTOSS generates c
19. he intervening time it has been used by 30 organizations including government organizations and large aerospace companies More can be found about the evolutionary details of GTOSS on the web site http home comcast net GTOSS The current GTOSS software system consists of a large body of Fortran 95 source code and 10 reference manuals describing all phases of user operation mathematical model derivations and system software design GTOSS programming is characterized by top down design object oriented structure modular isolation of environment models and convenient software hooks provided for user specific modifications The code is constrained to a highly portable subset of Fortran 95 and can run on virtually all computers with more or less minor modifications required to adhere to system compiler idiosyncrasies The ability to conduct automated verification of GTOSS execution is provided to substantiate correct installation and or user code modifications if desired This particular incarnation of GTOSS is specifically aimed at a Linux Unix installation in particular it should be a turn key installation for the Ubuntu distribution of Linux It must be stated up front that GTOSS is complex which in a sense simply reflects the complexity of the subject matter itself namely GTOSS allows the simulation of an arbitrary number of bodies connected in arbitrary fashion by an arbitrary number of tethers Thus it could simulate flight
20. ing itself and possibly complaining to the effect that the compiler was invoked but no source file was identified or some similar diagnostic type response On the other hand if the Terminal shell responds by telling you something like file or directory not found then likely what has happened is that your Unix PATH variable which specifies the search routes you proclaim to the system that you want followed in any attempt to honor an application execution attempt does not include a pathway to g95 To remedy this then you will want to modify your system PATH variable to include a path that leads to the compiler wherever you may find it to be C Pre Processing To compile properly under Fortran 95 GTOSS requires C preprocessing of the source prior to its being submitted to the Fortran compiler This is a compiler invoked function that is conventionally triggered by use of the source file name suffix of F90 The g95 compiler installation seems to automatically provide such capability if the compiler has been installed properly Failure to have pre processing on the GTOSS source will precipitate a myriad of compiler error messages most likely pertaining to un recognized or un declared variable names Fortran 95 Code Modules having compile errors and missing Modules etc etc It will be evident that something is gravely wrong with the compile process for instance it will not silently sneak up on the
21. ized as a legitimate Script input This could be a permissions type of problem that can be remedied by executing the following command from the terminal chmod 755 MakeGTOSS which will set proper permission for the Script file to be recognized in that role this problem can occur with ANY of the Script files contained in this delivery Note at a minimum the make files must reflect the choice of Fortran compiler This is specified is the 2 line in each make file and should either be FC g95 or FC gfortran or FC your system recognized name of whatever compiler you are using Now assume that compilation goes to completion but a link error occurs that interrupts creation of an executable application program This is usually because a program reference has been made to an external procedure that cannot be found If the bogus reference is traced to a source code routine as the culprit then that source module is usually identified and the problem can be remedied with dispatch However if no source procedure is identified then it is usually a system level library module that cannot be found such as crt1 or some such In this case culprit may be the absence of a required but uninstalled system library module Such missing modules can sometimes be attributed to non thorough manual installs of software This could be true of your Fortran install and is why g95 recommends using an installer package
22. ly the same way as your initial example run described above was conducted except now you will be executing complex simulations of all the various dynamically interesting aspects of the SE the Space Elevator dynamic genres addressed with these runs are SE Basic Tapered Ribbon Examination SE Nominal Stress State Examination SE Longitudinal Ribbon Modes SE Transverse Ribbon Modes SE Libration Dynamics 16 Getting Started with GTOSS SE Transverse Wave Propagation SE Stress Wave Propagation SE Climber Liftoff SE Climber Transit SE Climber Transit Arrest SE Climber Transit Resume SE Aerodynamic Response For each run genre there is a Word file describing multiple related runs special admonitions related to each run and a diagram of each simulated configuration Basic graphical results for these runs can be found in the SE Dynamics Handbook available on the SE Wiki For each INGOSS file there is one or more corresponding INCOSS file s these being input streams for CTOSS post processing of the simulation runs by using these INCOSS files CTOSS will generate the output data that has been presented in the corresponding sections of the Dynamics Handbook To execute these runs is quite simple but to fluently build on and extend these run explorations requires a significant background in Space Elevator analysis as well as simulation experience with complex dynamical systems however each run does represent a very con
23. of a sailing Frigate s chained cannonball shot or a wind tossed dirigible constrained by multiple mooring lines or a kite or the electro dynamic behavior of connected bare wire tethers in orbit or the modern day space elevator and everything in between Dynamics is a complicated scientific engineering discipline and tether dynamics is doubly so Correct results to tether dynamics problems are often non intuitive and complex to interpret As you use GTOSS before you conclude it is in error it should be pointed out that over a period of 30 years of serving GTOSS users of all levels and disciplines that 99 of the problems that were encountered by users have proven to be of the users own making due to having not read the documentation or a general lack of dynamics engineering experience that said legitimate bug detections reports are always welcome The GTOSS Applications The GTOSS complex consists of 5 executable programs GTOSS Conducts the actual tethered object simulation run DTOSS A post processor to provide printer friendly data output CTOSS A post processor to provide graphing program friendly data output UTOSS A post processor to provide other useful utility data output VTOSS Execute to accomplish the automated run verification capability The next section elaborates on the actual rolls played by the above application programs Getting Started with GTOSS How GTOSS W
24. olumn delimited text output friendly to plotting programs UTOSS provided to allow a user flexibility beyond that available in either DTOSS or CTOSS for post processing of the RDB For instance this PP is where various sub programs reside that create output formats specifically defined to drive animation programs this is also where the output data format is created to accomplish automated verification of GTOSS This PP is equally aimed at supporting outputs that are binary as well as text oriented The above three PP s can be thought of as an intermediary standing in as a tool for the user to gain access to the analytically defined variables of GTOSS that reside in the RDB The definition of the RDB format is generally of no concern to a GTOSS applications user only the set of subroutines constituting the RDB subsystem called RTOSS need be privy to details of the RDB design Thus during runtime the RTOSS routines grab the analytical variables of GTOSS dynamics definition and stow them in the RDB then at post processing time a set of RTOSS co routines reconstitute the time histories of these same analytical variables for the benefit of the user display The PP s then aggregate these analytical variables in user friendly arrangements for output Note If a user wants to expand on a particular PP s option offerings this is easily done via cloning then modifying a provided stubb and declaring it as a new output option for that
25. orks The GTOSS simulation program 1 First accepts an input text file created by the user per a format specified in the documentation said text file defining the dynamical system to be examined 2 Then performs a time domain simulation of the specified dynamic situation 3 As this simulation unfolds in time GTOSS periodically dumps data describing all aspects of this simulation into a set of Results Data Base files called the RDB this data is essentially an exhaustive compendium of analytical variables pertaining to a GTOSS solution As the last step the Post Processor Programs come into use 4 After the simulation has completed the user can then run Post Processing programs against the GTOSS generated RDB to produce user friendly results Note These post processed results above could be text printer friendly formats column delimited formats friendly to graphic display programs data formatted to drive specific animation programs for example data complying with an API defined per an animation application or even arbitrarily formatted data as defined by the user who would create a sub program that would access the RDB via an intermediary GTOSS program called UTOSS designed with just this intent in mind A Note on the RDB Scheme This scheme exists because one frequently never knows in advance just what data ultimately are going to be of interest or need examining after a simulation
26. oughout the GTOSS run here the user can again select from an array of terminal output pre formatted pages Thus expanding this example an actual GTOSS production run directory that might result from invoking all the post processors against a GTOSS simulation might look something like this GTOSS INGOSS GERROR OUTQUIK DTOSS INDOSS DERROR CTOSS INCOSS CERROR UTOSS INUOSS UERROR 13 Getting Started with GTOSS RDB files The results output file called OUTDIS created by DTOSS The results output file s created by CTOSS The results output file s created by UTOSS Note VTOSS is not included above since it is only brought into play to verify new versions of GTOSS code and is not a part of routine production usage of GTOSS Terminal Output and other Useful Results Some Unix Linux system implementations conveniently do two things automatically for you when you double click an executable application within a directory folder 1 It opens a terminal shell with the current working directory set to that directory from which the application is started AND 2 It starts the application executing Thus if the application is configured to output results to a shell terminal it can conveniently be monitored as the run proceeds This can of course be accomplished explicitly via a manual route namely after one has placed the copy of GTOSS in a folder with its associated INGOSS fil
27. r older than they are 18 Getting Started with GTOSS Recommended Reading Included in the GTOSS delivery area are a number of pdf files containing extensive documentation of GTOSS operation In order of decreasing importance with Red meaning MOST important GTOSS Reference Manual At least a skim read of Sections 1 2 4 very important 5 6 8 10 11 12 TOSS Reference Manual At least a skim read of Sections 2 3 5 6 7 very important 8 Quick Reference Manual This volume contains a potpourri of information some of which is unique to this document others of which has been duplicated and shortened from other documents for which frequent reference is made but all of which has been found to be highly useful whether setting up runs or modifying code This is the bread and butter day to day stalwart of the GTOSS documentation The first section in the Quick Ref is particularly valuable in interpreting results data as much of these results are referenced to the various frame definitions within GTOSS This also boils down concisely much of the information pertaining to the myriad of dynamics Initialization Execution and Control options G TOSS Equations Reference Manual Provides detailed equation derivations modeling assumptions and the equivalence mappings between analytical dynamics symbols to Fortran variable names This is an abstruse dissertation the full understanding of which would require si
28. sGsactanncosncdetvsuasiaseaeseveeussonnceussuanetusentsesvecnensa stesso 10 Building Post PrOCESSOTS ics csciscs cas sacdeecesasedcassscshadcaossasasesesecaaspeencetoensecccaesascbiseetbesesube 12 Resulting Application Programs esssessseessoeessosssoessoesssosesoessoosesosesoesssoessoesssosssossss 12 Make file Options and Using the Other Script Files sscssssssscssssosssesseeoees 12 Running GLOSS eeseesescssessssssssssosossossccoccococeececocecesesesesessessssess 13 How To Do It and What Happens scsssssseesacciasacavetievsscvsdcencocnsecsanceseanesevacpsodvedsensncesans 13 Terminal Output and other Useful Results sseeseesoesoeesossoesoessoesoeseoesossoeseoesossoee 14 Error ReportS s sssssssiosissessesosissesssssossesocossasosiso oosnsisoss svossesssoessos sas essosssi seesi io seess ossos 14 Making Your First Example GTOSS Run sssesseesossoessoesoesoessoesoesceessoesoesoeesoesoessessoesoe 15 Making More Advanced Space Elevator Explorations e ssessessessoesoessoesoesosesossoesoe 16 Admonitions sssessssssossesseosssosossooscosscssessesssosscosesssossossooseosssssesss LS Recommended Reading essssssssssssscssecsccoccoecoeececceeecececesessssee LD Getting Started with GTOSS OVERVIEW What is GTOSS GTOSS stands for Generalized Tethered Object Simulation System It has a rich genealogy dating back almost 30 years to its initial development under the sponsorship of NASA in t
29. urce for GTOSS sub system for TOSS Bodies A_FOSS source for GTOSS sub system for Tethers A_ROSS source for GTOSS RDB sub system A_BOSS source for GTOSS Flexible boom RDB sub system A_ENVR source for natural environment models A_UTIL source for general Utility routines A_DOSS source for Post Processor program DTOSS A_COSS source for Post Processor program CTOSS A_UOSS source for Post Processor program UTOSS A_VOSS source for Post Processor program VTOSS A__RUN input data files for reference and for verification verify GTOSSv12 data images of correct reference version of GTOSS the delivery script files GNU make files and other useful scripts Getting Started with GTOSS Revealed below are the contents of various chosen directories from above A_RUN GRUNS INGOSS files for verification and reference DRUNS INDOSS files for verification and reference URUNS INUOSS files for verification and reference CRUNS INCOSS files for chosen runs defined in GRUNS VRUNS INVOSS files for chosen examples Nom SE Ribbon Data Text Data snippet for specifying the nominal tapered Space Elevator ribbon specification within an IGOSS file to reflect the original ribbon design of Brad Edwards INGOSS_Late_Start_run_setup Examples of specifying the Late Start feature assorted script files GNU make files and other s
30. utine that decided to execute a Stop and some indication of the location within a routine where the Stop occurred some routine can have many types of error detection events If a Stop occurs one can examine the routine for possibly more info BUT one should always check the GERROR file as these Stops are frequently attended by an intelligent error diagnosis being written to the GERROR file by the offended routine There are a class of numerical errors that occur when catastrophic numerical instability sets in upon the integration processes within GTOSS These frequently show up as a Stop in certain Utility routines such as VECNRM and is usually a manifestation of the fact that numerics have gone bad ie floating point under over flows zeroes in denominators where they shouldn t be etc etc One very quickly learns to recognize the artifacts of this error and if you examine the numeric results this is frequently preceded by pathological and erratic behavior and oscillations in numerical values etc This is why it is mandatory to read the section in both the GTOSS and TOSS reference manuals pertaining to Numerical stability Making Your First Example GTOSS Run To be concrete we will make an example Space Elevator related run Create a directory say SE_Run Make a copy of the executable programs GTOSS and CTOSS into this directory Now in the delivery data there is a directory folder within which is an INGOSS and IN
31. venient starting point to in fact proceed along these lines thus saving the user significant time developing new explorations stemming from those already done 17 Getting Started with GTOSS Admonitions As the author of GTOSS who has served the engineering aerospace tether community for over 30 years providing formal class instruction in the use of GTOSS and tether dynamics informal help to many users GTOSS installation at enumerable facilities on enumerable different computer platforms and operating systems general consulting and conducting design studies for many clients I have made the following observations 99 of the problems perceived by the user as being a bug in GTOSS is in fact a user precipitated error either an overt miscue in interpreting and or entering physical system specification data and execution options or inattention to numerical convergence of integrated time domain dynamics solutions or a lack of understanding in interpreting results One of the most insidious and common problems that tend to plague new users is the failure to be ever vigilant in insuring the Numerical Convergence of the integrated solutions to the GTOSS equations To this end it is mandatory that a new user read and understand fully Section 4 of the GTOSS User Manual and Section 7 of the TOSS User manual Both non converged as well as fully diverged numerical solutions are easy to detect and remedy but the user must become aware o
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