Running: ./testmodel.py --libraries=/home/hudson/saved_omc/libraries/.openmodelica/libraries/ --ompython_omhome=/usr IDEAS_IDEAS.Airflow.Multizone.Examples.ChimneyShaftWithVolume.conf.json
loadFile("/home/hudson/saved_omc/libraries/.openmodelica/libraries/ModelicaServices 4.0.0+maint.om/package.mo", uses=false)
loadFile("/home/hudson/saved_omc/libraries/.openmodelica/libraries/Complex 4.0.0+maint.om/package.mo", uses=false)
loadFile("/home/hudson/saved_omc/libraries/.openmodelica/libraries/Modelica 4.0.0+maint.om/package.mo", uses=false)
loadFile("/home/hudson/saved_omc/libraries/.openmodelica/libraries/IDEAS 3.0.0/package.mo", uses=false)
Using package IDEAS with version 3.0.0 (/home/hudson/saved_omc/libraries/.openmodelica/libraries/IDEAS 3.0.0/package.mo)
Using package Modelica with version 4.0.0 (/home/hudson/saved_omc/libraries/.openmodelica/libraries/Modelica 4.0.0+maint.om/package.mo)
Using package Complex with version 4.0.0 (/home/hudson/saved_omc/libraries/.openmodelica/libraries/Complex 4.0.0+maint.om/package.mo)
Using package ModelicaServices with version 4.0.0 (/home/hudson/saved_omc/libraries/.openmodelica/libraries/ModelicaServices 4.0.0+maint.om/package.mo)
Running command: "" <> buildModelFMU(IDEAS.Airflow.Multizone.Examples.ChimneyShaftWithVolume,fileNamePrefix="IDEAS_IDEAS_Airflow_Multizone_Examples_ChimneyShaftWithVolume",fmuType="me",version="2.0",platforms={"static"})
"" <> buildModelFMU(IDEAS.Airflow.Multizone.Examples.ChimneyShaftWithVolume,fileNamePrefix="IDEAS_IDEAS_Airflow_Multizone_Examples_ChimneyShaftWithVolume",fmuType="me",version="2.0",platforms={"static"})
Notification: Performance of loadFile(/home/hudson/saved_omc/libraries/.openmodelica/libraries/ModelicaServices 4.0.0+maint.om/package.mo): time 0.0008519/0.0008518, allocations: 91.84 kB / 15.06 MB, free: 1.098 MB / 14.72 MB
Notification: Performance of loadFile(/home/hudson/saved_omc/libraries/.openmodelica/libraries/Complex 4.0.0+maint.om/package.mo): time 0.001089/0.001089, allocations: 172.7 kB / 15.95 MB, free: 208 kB / 14.72 MB
Notification: Performance of loadFile(/home/hudson/saved_omc/libraries/.openmodelica/libraries/Modelica 4.0.0+maint.om/package.mo): time 1.399/1.399, allocations: 223.2 MB / 240 MB, free: 5.195 MB / 190.1 MB
Notification: Performance of loadFile(/home/hudson/saved_omc/libraries/.openmodelica/libraries/IDEAS 3.0.0/package.mo): time 0.8275/0.8275, allocations: 132.3 MB / 423.4 MB, free: 1.98 MB / 350.1 MB
Notification: Performance of FrontEnd - loaded program: time 0.0003355/0.0003357, allocations: 9.312 kB / 0.5035 GB, free: 4.133 MB / 366.1 MB
Notification: Performance of FrontEnd - Absyn->SCode: time 0.4832/0.4836, allocations: 81.57 MB / 0.5831 GB, free: 3.969 MB / 430.1 MB
Notification: Performance of NFInst.instantiate(IDEAS.Airflow.Multizone.Examples.ChimneyShaftWithVolume): time 0.2361/0.7197, allocations: 215 MB / 0.7931 GB, free: 8.949 MB / 0.6231 GB
Notification: Performance of NFInst.instExpressions: time 0.0153/0.7351, allocations: 9.79 MB / 0.8027 GB, free: 15.14 MB / 0.6387 GB
Notification: Performance of NFInst.updateImplicitVariability: time 0.002862/0.738, allocations: 47.69 kB / 0.8027 GB, free: 15.1 MB / 0.6387 GB
Notification: Performance of NFTyping.typeComponents: time 0.00289/0.7409, allocations: 0.804 MB / 0.8035 GB, free: 14.29 MB / 0.6387 GB
Notification: Performance of NFTyping.typeBindings: time 0.008868/0.7498, allocations: 2.658 MB / 0.8061 GB, free: 11.62 MB / 0.6387 GB
Notification: Performance of NFTyping.typeClassSections: time 0.00478/0.7546, allocations: 1.439 MB / 0.8075 GB, free: 10.19 MB / 0.6387 GB
Notification: Performance of NFFlatten.flatten: time 0.006542/0.7612, allocations: 5.273 MB / 0.8127 GB, free: 4.895 MB / 0.6387 GB
Notification: Performance of NFFlatten.resolveConnections: time 0.002127/0.7633, allocations: 1.174 MB / 0.8138 GB, free: 3.695 MB / 0.6387 GB
Notification: Performance of NFEvalConstants.evaluate: time 0.002968/0.7663, allocations: 1.358 MB / 0.8151 GB, free: 2.332 MB / 0.6387 GB
Notification: Performance of NFSimplifyModel.simplify: time 0.002685/0.769, allocations: 1.405 MB / 0.8165 GB, free: 0.9219 MB / 0.6387 GB
Notification: Performance of NFPackage.collectConstants: time 0.0003174/0.7693, allocations: 76 kB / 0.8166 GB, free: 0.8477 MB / 0.6387 GB
Notification: Performance of NFFlatten.collectFunctions: time 0.4629/1.232, allocations: 1.615 MB / 0.8182 GB, free: 12.45 MB / 0.6387 GB
Notification: Performance of NFScalarize.scalarize: time 0.001469/1.234, allocations: 0.5735 MB / 0.8187 GB, free: 12.45 MB / 0.6387 GB
Notification: Performance of NFVerifyModel.verify: time 0.001104/1.235, allocations: 411 kB / 0.8191 GB, free: 12.42 MB / 0.6387 GB
Notification: Performance of NFConvertDAE.convert: time 0.00535/1.24, allocations: 2.572 MB / 0.8216 GB, free: 12.34 MB / 0.6387 GB
Notification: Performance of FrontEnd - DAE generated: time 7.685e-06/1.24, allocations: 0 / 0.8216 GB, free: 12.34 MB / 0.6387 GB
Notification: Performance of FrontEnd: time 3.707e-06/1.24, allocations: 2.156 kB / 0.8216 GB, free: 12.34 MB / 0.6387 GB
Notification: Performance of Transformations before backend: time 8.64e-05/1.24, allocations: 0 / 0.8216 GB, free: 12.34 MB / 0.6387 GB
Notification: Model statistics after passing the front-end and creating the data structures used by the back-end:
 * Number of equations: 344
 * Number of variables: 344
Notification: Performance of Generate backend data structure: time 0.006332/1.247, allocations: 2.144 MB / 0.8237 GB, free: 11.27 MB / 0.6387 GB
Notification: Performance of prepare preOptimizeDAE: time 5.11e-05/1.247, allocations: 8.906 kB / 0.8237 GB, free: 11.27 MB / 0.6387 GB
Notification: Performance of preOpt introduceOutputAliases (simulation): time 0.0004303/1.247, allocations: 201.8 kB / 0.8239 GB, free: 11.23 MB / 0.6387 GB
Notification: Performance of preOpt normalInlineFunction (simulation): time 0.003661/1.251, allocations: 0.5297 MB / 0.8244 GB, free: 11.12 MB / 0.6387 GB
Notification: Performance of preOpt evaluateParameters (simulation): time 0.002533/1.253, allocations: 1.183 MB / 0.8256 GB, free: 10.74 MB / 0.6387 GB
Notification: Performance of preOpt simplifyIfEquations (simulation): time 9.507e-05/1.254, allocations: 98.5 kB / 0.8257 GB, free: 10.74 MB / 0.6387 GB
Notification: Performance of preOpt expandDerOperator (simulation): time 0.0002299/1.254, allocations: 138 kB / 0.8258 GB, free: 10.74 MB / 0.6387 GB
Notification: Performance of preOpt clockPartitioning (simulation): time 0.003163/1.257, allocations: 1.66 MB / 0.8274 GB, free: 10.54 MB / 0.6387 GB
Notification: Performance of preOpt findStateOrder (simulation): time 3.665e-05/1.257, allocations: 2.531 kB / 0.8274 GB, free: 10.54 MB / 0.6387 GB
Notification: Performance of preOpt replaceEdgeChange (simulation): time 0.0001334/1.257, allocations: 55.66 kB / 0.8275 GB, free: 10.54 MB / 0.6387 GB
Notification: Performance of preOpt inlineArrayEqn (simulation): time 0.00011/1.257, allocations: 79.33 kB / 0.8276 GB, free: 10.53 MB / 0.6387 GB
Notification: Performance of preOpt removeEqualRHS (simulation): time 0.002873/1.26, allocations: 1.44 MB / 0.829 GB, free: 10.51 MB / 0.6387 GB
Warning: The model contains alias variables with redundant start and/or conflicting nominal values. It is recommended to resolve the conflicts, because otherwise the system could be hard to solve. To print the conflicting alias sets and the chosen candidates please use -d=aliasConflicts.
Notification: Performance of preOpt removeSimpleEquations (simulation): time 0.01054/1.271, allocations: 6.95 MB / 0.8358 GB, free: 23.13 MB / 0.6544 GB
Notification: Performance of preOpt comSubExp (simulation): time 0.002022/1.273, allocations: 1.19 MB / 0.8369 GB, free: 22.91 MB / 0.6544 GB
Notification: Performance of preOpt resolveLoops (simulation): time 0.00108/1.274, allocations: 0.6192 MB / 0.8375 GB, free: 22.89 MB / 0.6544 GB
Notification: Performance of preOpt evalFunc (simulation): time 0.0009695/1.275, allocations: 0.8643 MB / 0.8384 GB, free: 21.95 MB / 0.6544 GB
Notification: Performance of preOpt encapsulateWhenConditions (simulation): time 0.001216/1.276, allocations: 0.6048 MB / 0.839 GB, free: 21.9 MB / 0.6544 GB
Notification: Performance of pre-optimization done (n=110): time 3.707e-06/1.276, allocations: 3.547 kB / 0.839 GB, free: 21.9 MB / 0.6544 GB
Notification: Performance of matching and sorting (n=110): time 0.003472/1.28, allocations: 1.575 MB / 0.8405 GB, free: 21.78 MB / 0.6544 GB
Notification: Performance of inlineWhenForInitialization (initialization): time 6.478e-05/1.28, allocations: 93.89 kB / 0.8406 GB, free: 21.68 MB / 0.6544 GB
Notification: Performance of selectInitializationVariablesDAE (initialization): time 0.001519/1.281, allocations: 1.181 MB / 0.8418 GB, free: 21.52 MB / 0.6544 GB
Notification: Performance of collectPreVariables (initialization): time 0.0001235/1.281, allocations: 48.7 kB / 0.8418 GB, free: 21.48 MB / 0.6544 GB
Notification: Performance of collectInitialEqns (initialization): time 0.000512/1.282, allocations: 0.6779 MB / 0.8425 GB, free: 21.25 MB / 0.6544 GB
Notification: Performance of collectInitialBindings (initialization): time 0.0003608/1.282, allocations: 389.1 kB / 0.8428 GB, free: 21 MB / 0.6544 GB
Notification: Performance of simplifyInitialFunctions (initialization): time 5.323e-05/1.282, allocations: 19.25 kB / 0.8429 GB, free: 21 MB / 0.6544 GB
Notification: Performance of setup shared object (initialization): time 0.0001178/1.282, allocations: 345.1 kB / 0.8432 GB, free: 20.7 MB / 0.6544 GB
Notification: Performance of preBalanceInitialSystem (initialization): time 0.0006406/1.283, allocations: 414.8 kB / 0.8436 GB, free: 20.7 MB / 0.6544 GB
Notification: Performance of partitionIndependentBlocks (initialization): time 0.000718/1.284, allocations: 0.5722 MB / 0.8441 GB, free: 20.57 MB / 0.6544 GB
Notification: Performance of analyzeInitialSystem (initialization): time 0.0007344/1.285, allocations: 494.2 kB / 0.8446 GB, free: 20.57 MB / 0.6544 GB
Notification: Performance of solveInitialSystemEqSystem (initialization): time 4.779e-06/1.285, allocations: 3.062 kB / 0.8446 GB, free: 20.57 MB / 0.6544 GB
Notification: Performance of matching and sorting (n=126) (initialization): time 0.00195/1.287, allocations: 1.208 MB / 0.8458 GB, free: 20.46 MB / 0.6544 GB
Notification: Performance of prepare postOptimizeDAE: time 9.562e-05/1.287, allocations: 174.1 kB / 0.846 GB, free: 20.27 MB / 0.6544 GB
Notification: Performance of postOpt simplifyComplexFunction (initialization): time 1.015e-05/1.287, allocations: 2.906 kB / 0.846 GB, free: 20.27 MB / 0.6544 GB
Notification: Performance of postOpt tearingSystem (initialization): time 2.325e-05/1.287, allocations: 5.312 kB / 0.846 GB, free: 20.27 MB / 0.6544 GB
Notification: Performance of postOpt solveSimpleEquations (initialization): time 0.000915/1.288, allocations: 221.3 kB / 0.8462 GB, free: 20.27 MB / 0.6544 GB
Notification: Performance of postOpt calculateStrongComponentJacobians (initialization): time 1.441e-05/1.288, allocations: 9.406 kB / 0.8462 GB, free: 20.27 MB / 0.6544 GB
Notification: Performance of postOpt simplifyAllExpressions (initialization): time 0.00168/1.289, allocations: 165 kB / 0.8463 GB, free: 20.21 MB / 0.6544 GB
Notification: Performance of postOpt collapseArrayExpressions (initialization): time 9.618e-05/1.289, allocations: 37.44 kB / 0.8464 GB, free: 20.21 MB / 0.6544 GB
Notification: Performance of prepare postOptimizeDAE: time 9.488e-06/1.289, allocations: 5.031 kB / 0.8464 GB, free: 20.21 MB / 0.6544 GB
Notification: Performance of postOpt replaceHomotopyWithSimplified (initialization): time 0.00148/1.291, allocations: 1.034 MB / 0.8474 GB, free: 20.2 MB / 0.6544 GB
Notification: Performance of postOpt simplifyComplexFunction (initialization): time 6.933e-06/1.291, allocations: 3.781 kB / 0.8474 GB, free: 20.2 MB / 0.6544 GB
Notification: Performance of postOpt tearingSystem (initialization): time 1.164e-05/1.291, allocations: 9.328 kB / 0.8474 GB, free: 20.2 MB / 0.6544 GB
Notification: Performance of postOpt solveSimpleEquations (initialization): time 0.0007976/1.292, allocations: 211.5 kB / 0.8476 GB, free: 20.2 MB / 0.6544 GB
Notification: Performance of postOpt calculateStrongComponentJacobians (initialization): time 1.145e-05/1.292, allocations: 9.25 kB / 0.8476 GB, free: 20.2 MB / 0.6544 GB
Notification: Performance of postOpt simplifyAllExpressions (initialization): time 0.001558/1.293, allocations: 169.4 kB / 0.8478 GB, free: 20.14 MB / 0.6544 GB
Notification: Performance of postOpt collapseArrayExpressions (initialization): time 7.399e-05/1.293, allocations: 36.78 kB / 0.8478 GB, free: 20.14 MB / 0.6544 GB
Notification: Model statistics after passing the back-end for initialization:
 * Number of independent subsystems: 11
 * Number of states: 0 ()
 * Number of discrete variables: 5 ($whenCondition1,$PRE.mRoo_flow.nextTimeEvent,mRoo_flow.nextTimeEvent,$PRE.mRoo_flow.nextTimeEventScaled,mRoo_flow.nextTimeEventScaled)
 * Number of discrete states: 0 ()
 * Number of clocked states: 0 ()
 * Top-level inputs: 0
Notification: Strong component statistics for initialization (126):
 * Single equations (assignments): 126
 * Array equations: 0
 * Algorithm blocks: 0
 * Record equations: 0
 * When equations: 0
 * If-equations: 0
 * Equation systems (linear and non-linear blocks): 0
 * Torn equation systems: 0
 * Mixed (continuous/discrete) equation systems: 0
Notification: Performance of prepare postOptimizeDAE: time 0.001011/1.294, allocations: 483.2 kB / 0.8483 GB, free: 19.95 MB / 0.6544 GB
Notification: Performance of postOpt lateInlineFunction (simulation): time 0.0002764/1.295, allocations: 149.3 kB / 0.8484 GB, free: 19.88 MB / 0.6544 GB
Notification: Performance of postOpt wrapFunctionCalls (simulation): time 0.002096/1.297, allocations: 1.243 MB / 0.8496 GB, free: 19.79 MB / 0.6544 GB
Notification: Performance of postOpt inlineArrayEqn (simulation): time 1.175e-05/1.297, allocations: 15.56 kB / 0.8496 GB, free: 19.78 MB / 0.6544 GB
Notification: Performance of postOpt constantLinearSystem (simulation): time 7.635e-06/1.297, allocations: 0 / 0.8496 GB, free: 19.78 MB / 0.6544 GB
Notification: Performance of postOpt simplifysemiLinear (simulation): time 0.001551/1.298, allocations: 1.01 MB / 0.8506 GB, free: 19.69 MB / 0.6544 GB
Notification: Performance of postOpt removeSimpleEquations (simulation): time 0.005086/1.304, allocations: 3.167 MB / 0.8537 GB, free: 19.07 MB / 0.6544 GB
Notification: Performance of postOpt simplifyComplexFunction (simulation): time 6.903e-06/1.304, allocations: 0 / 0.8537 GB, free: 19.07 MB / 0.6544 GB
Notification: Performance of postOpt solveSimpleEquations (simulation): time 0.001062/1.305, allocations: 236.9 kB / 0.8539 GB, free: 19.07 MB / 0.6544 GB
Notification: Performance of postOpt tearingSystem (simulation): time 1.141e-05/1.305, allocations: 6.469 kB / 0.854 GB, free: 19.07 MB / 0.6544 GB
Notification: Performance of postOpt inputDerivativesUsed (simulation): time 7.301e-05/1.305, allocations: 29.23 kB / 0.854 GB, free: 19.07 MB / 0.6544 GB
Notification: Performance of postOpt calculateStrongComponentJacobians (simulation): time 8.797e-06/1.305, allocations: 8.172 kB / 0.854 GB, free: 19.07 MB / 0.6544 GB
Notification: Performance of postOpt calculateStateSetsJacobians (simulation): time 3.437e-06/1.305, allocations: 5.844 kB / 0.854 GB, free: 19.07 MB / 0.6544 GB
Notification: Performance of postOpt symbolicJacobian (simulation): time 0.00272/1.307, allocations: 1.999 MB / 0.8559 GB, free: 18.73 MB / 0.6544 GB
Notification: Performance of postOpt removeConstants (simulation): time 0.0008558/1.308, allocations: 365.5 kB / 0.8563 GB, free: 18.54 MB / 0.6544 GB
Notification: Performance of postOpt simplifyTimeIndepFuncCalls (simulation): time 0.0001947/1.309, allocations: 23.09 kB / 0.8563 GB, free: 18.54 MB / 0.6544 GB
Notification: Performance of postOpt simplifyAllExpressions (simulation): time 0.001023/1.31, allocations: 113.4 kB / 0.8564 GB, free: 18.53 MB / 0.6544 GB
Notification: Performance of postOpt findZeroCrossings (simulation): time 0.0001534/1.31, allocations: 83.53 kB / 0.8565 GB, free: 18.52 MB / 0.6544 GB
Notification: Performance of postOpt collapseArrayExpressions (simulation): time 7.635e-05/1.31, allocations: 39.28 kB / 0.8565 GB, free: 18.52 MB / 0.6544 GB
Notification: Performance of sorting global known variables: time 0.001091/1.311, allocations: 0.8184 MB / 0.8573 GB, free: 18.41 MB / 0.6544 GB
Notification: Performance of sort global known variables: time 3.41e-07/1.311, allocations: 0 / 0.8573 GB, free: 18.41 MB / 0.6544 GB
Notification: Performance of remove unused functions: time 0.002041/1.313, allocations: 0.8371 MB / 0.8582 GB, free: 18.29 MB / 0.6544 GB
Notification: Model statistics after passing the back-end for simulation:
 * Number of independent subsystems: 11
 * Number of states: 9 (roo.dynBal.U,roo.dynBal.m,roo.dynBal.mXi[1],oriChiTop.mExc,oriBot.mExc,oriChiBot.mExc,sha.vol.dynBal.U,sha.vol.dynBal.m,sha.vol.dynBal.mXi[1])
 * Number of discrete variables: 3 ($whenCondition1,mRoo_flow.nextTimeEvent,mRoo_flow.nextTimeEventScaled)
 * Number of discrete states: 2 (mRoo_flow.nextTimeEvent,mRoo_flow.nextTimeEventScaled)
 * Number of clocked states: 0 ()
 * Top-level inputs: 0
Notification: Strong component statistics for simulation (110):
 * Single equations (assignments): 108
 * Array equations: 0
 * Algorithm blocks: 0
 * Record equations: 0
 * When equations: 2
 * If-equations: 0
 * Equation systems (linear and non-linear blocks): 0
 * Torn equation systems: 0
 * Mixed (continuous/discrete) equation systems: 0
Notification: Performance of Backend phase and start with SimCode phase: time 0.004141/1.317, allocations: 3.023 MB / 0.8611 GB, free: 17.34 MB / 0.6544 GB
Notification: Performance of simCode: created initialization part: time 0.002506/1.32, allocations: 1.605 MB / 0.8627 GB, free: 17.31 MB / 0.6544 GB
Notification: Performance of simCode: created event and clocks part: time 7.244e-06/1.32, allocations: 4.062 kB / 0.8627 GB, free: 17.3 MB / 0.6544 GB
Notification: Performance of simCode: created simulation system equations: time 0.0007962/1.32, allocations: 0.5686 MB / 0.8632 GB, free: 17.3 MB / 0.6544 GB
Notification: Performance of simCode: created of all other equations (e.g. parameter, nominal, assert, etc): time 0.003957/1.324, allocations: 0.8323 MB / 0.8641 GB, free: 17.24 MB / 0.6544 GB
Notification: Performance of simCode: created linear, non-linear and system jacobian parts: time 0.01549/1.34, allocations: 9.689 MB / 0.8735 GB, free: 13.62 MB / 0.6544 GB
Notification: Performance of simCode: some other stuff during SimCode phase: time 0.000953/1.341, allocations: 1.372 MB / 0.8749 GB, free: 12.88 MB / 0.6544 GB
Notification: Performance of simCode: alias equations: time 0.002129/1.343, allocations: 455.7 kB / 0.8753 GB, free: 12.77 MB / 0.6544 GB
Notification: Performance of simCode: all other stuff during SimCode phase: time 0.0008481/1.344, allocations: 0.6239 MB / 0.8759 GB, free: 12.77 MB / 0.6544 GB
Notification: Performance of SimCode: time 9.22e-07/1.344, allocations: 0 / 0.8759 GB, free: 12.77 MB / 0.6544 GB
Notification: Performance of buildModelFMU: Generate the FMI files: time 0.07124/1.415, allocations: 41.66 MB / 0.9166 GB, free: 3.395 MB / 0.67 GB
Notification: Performance of buildModelFMU: configured platform static using cached values: time 0.0001921/1.415, allocations: 220.8 kB / 0.9168 GB, free: 3.16 MB / 0.67 GB
Notification: Performance of buildModelFMU: Generate platform static: time 2.774/4.19, allocations: 0 / 0.9168 GB, free: 3.16 MB / 0.67 GB
(rm -f IDEAS_IDEAS.Airflow.Multizone.Examples.ChimneyShaftWithVolume.pipe ; mkfifo IDEAS_IDEAS.Airflow.Multizone.Examples.ChimneyShaftWithVolume.pipe ; head -c 1048576 < IDEAS_IDEAS.Airflow.Multizone.Examples.ChimneyShaftWithVolume.pipe >> ../files/IDEAS_IDEAS.Airflow.Multizone.Examples.ChimneyShaftWithVolume.sim & /home/hudson/saved_omc/OMSimulator/install/linux/bin/OMSimulator  --tempDir=temp_IDEAS_IDEAS_Airflow_Multizone_Examples_ChimneyShaftWithVolume_fmu --startTime=0 --stopTime=3600 --timeout=50 --tolerance=1e-06 IDEAS_IDEAS_Airflow_Multizone_Examples_ChimneyShaftWithVolume.fmu > IDEAS_IDEAS.Airflow.Multizone.Examples.ChimneyShaftWithVolume.pipe 2>&1)
Environment - environmentSimulation: