Running: ./testmodel.py --libraries=/home/hudson/saved_omc/libraries/.openmodelica/libraries/ --ompython_omhome=/usr Buildings_maint.7.0.x_Buildings.Fluid.HeatExchangers.CoolingTowers.Validation.MerkelEnergyPlus.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 3.2.3+maint.om/package.mo", uses=false)
loadFile("/home/hudson/saved_omc/libraries/.openmodelica/libraries/Buildings 7.0.3-maint.7.0.x/package.mo", uses=false)
Using package Buildings with version 7.0.3 (/home/hudson/saved_omc/libraries/.openmodelica/libraries/Buildings 7.0.3-maint.7.0.x/package.mo)
Using package Modelica with version 3.2.3 (/home/hudson/saved_omc/libraries/.openmodelica/libraries/Modelica 3.2.3+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: translateModel(Buildings.Fluid.HeatExchangers.CoolingTowers.Validation.MerkelEnergyPlus,tolerance=1e-06,outputFormat="empty",numberOfIntervals=5000,variableFilter="",fileNamePrefix="Buildings_maint.7.0.x_Buildings.Fluid.HeatExchangers.CoolingTowers.Validation.MerkelEnergyPlus")
translateModel(Buildings.Fluid.HeatExchangers.CoolingTowers.Validation.MerkelEnergyPlus,tolerance=1e-06,outputFormat="empty",numberOfIntervals=5000,variableFilter="",fileNamePrefix="Buildings_maint.7.0.x_Buildings.Fluid.HeatExchangers.CoolingTowers.Validation.MerkelEnergyPlus")
Notification: Performance of loadFile(/home/hudson/saved_omc/libraries/.openmodelica/libraries/ModelicaServices 4.0.0+maint.om/package.mo): time 0.0007849/0.0007849, allocations: 90.83 kB / 15.36 MB, free: 0.7383 MB / 14.72 MB
Notification: Performance of loadFile(/home/hudson/saved_omc/libraries/.openmodelica/libraries/Complex 4.0.0+maint.om/package.mo): time 0.005852/0.005853, allocations: 172.3 kB / 16.26 MB, free: 6.613 MB / 14.72 MB
Notification: Performance of loadFile(/home/hudson/saved_omc/libraries/.openmodelica/libraries/Modelica 3.2.3+maint.om/package.mo): time 1.327/1.327, allocations: 205.4 MB / 222.4 MB, free: 5.562 MB / 174.1 MB
Notification: Performance of loadFile(/home/hudson/saved_omc/libraries/.openmodelica/libraries/Buildings 7.0.3-maint.7.0.x/package.mo): time 1.516/1.516, allocations: 252 MB / 0.5105 GB, free: 4.633 MB / 414.1 MB
Notification: Modelica requested package Complex of version 3.2.3. Complex 4.0.0 is used instead which states that it is fully compatible without conversion script needed.
Notification: Modelica requested package ModelicaServices of version 3.2.3. ModelicaServices 4.0.0 is used instead which states that it is fully compatible without conversion script needed.
Notification: Performance of FrontEnd - loaded program: time 0.0004777/0.0004777, allocations: 20 kB / 0.6249 GB, free: 0.6797 MB / 0.5137 GB
Notification: Performance of FrontEnd - Absyn->SCode: time 0.466/0.4665, allocations: 106.3 MB / 0.7287 GB, free: 11.25 MB / 0.545 GB
Notification: Performance of NFInst.instantiate(Buildings.Fluid.HeatExchangers.CoolingTowers.Validation.MerkelEnergyPlus): time 0.1803/0.6469, allocations: 176.5 MB / 0.9011 GB, free: 10.05 MB / 0.7169 GB
Notification: Performance of NFInst.instExpressions: time 0.4786/1.125, allocations: 13.11 MB / 0.9139 GB, free: 10.4 MB / 0.7169 GB
Notification: Performance of NFInst.updateImplicitVariability: time 0.002457/1.128, allocations: 27.28 kB / 0.9139 GB, free: 10.4 MB / 0.7169 GB
Notification: Performance of NFTyping.typeComponents: time 0.002104/1.13, allocations: 435.7 kB / 0.9144 GB, free: 10.4 MB / 0.7169 GB
Notification: Performance of NFTyping.typeBindings: time 0.007139/1.137, allocations: 2.019 MB / 0.9163 GB, free: 10.35 MB / 0.7169 GB
Notification: Performance of NFTyping.typeClassSections: time 0.003547/1.141, allocations: 0.9528 MB / 0.9173 GB, free: 10.31 MB / 0.7169 GB
Notification: Performance of NFFlatten.flatten: time 0.005507/1.146, allocations: 2.967 MB / 0.9202 GB, free: 10.31 MB / 0.7169 GB
Notification: Performance of NFFlatten.resolveConnections: time 0.001489/1.148, allocations: 0.6639 MB / 0.9208 GB, free: 10.23 MB / 0.7169 GB
Notification: Performance of NFEvalConstants.evaluate: time 0.001954/1.15, allocations: 0.7362 MB / 0.9215 GB, free: 10.22 MB / 0.7169 GB
Notification: Performance of NFSimplifyModel.simplify: time 0.001321/1.151, allocations: 0.6755 MB / 0.9222 GB, free: 10.22 MB / 0.7169 GB
Notification: Performance of NFPackage.collectConstants: time 0.0001563/1.151, allocations: 46.19 kB / 0.9222 GB, free: 10.22 MB / 0.7169 GB
Notification: Performance of NFFlatten.collectFunctions: time 0.00606/1.157, allocations: 2.259 MB / 0.9244 GB, free: 10.18 MB / 0.7169 GB
Notification: Performance of NFScalarize.scalarize: time 0.0005479/1.158, allocations: 280.7 kB / 0.9247 GB, free: 10.18 MB / 0.7169 GB
Notification: Performance of NFVerifyModel.verify: time 0.001024/1.159, allocations: 0.5747 MB / 0.9253 GB, free: 10.15 MB / 0.7169 GB
Notification: Performance of NFConvertDAE.convert: time 0.004728/1.164, allocations: 2.626 MB / 0.9278 GB, free: 9.984 MB / 0.7169 GB
Notification: Performance of FrontEnd - DAE generated: time 3.747e-06/1.164, allocations: 0 / 0.9278 GB, free: 9.984 MB / 0.7169 GB
Notification: Performance of FrontEnd: time 1.292e-06/1.164, allocations: 0 / 0.9278 GB, free: 9.984 MB / 0.7169 GB
Notification: Performance of Transformations before backend: time 1.752e-05/1.164, allocations: 0 / 0.9278 GB, free: 9.984 MB / 0.7169 GB
Notification: Model statistics after passing the front-end and creating the data structures used by the back-end:
 * Number of equations: 143
 * Number of variables: 143
Notification: Performance of Generate backend data structure: time 0.002691/1.167, allocations: 1.566 MB / 0.9294 GB, free: 9.004 MB / 0.7169 GB
Notification: Performance of prepare preOptimizeDAE: time 4.041e-05/1.167, allocations: 8.656 kB / 0.9294 GB, free: 9.004 MB / 0.7169 GB
Notification: Performance of preOpt normalInlineFunction (simulation): time 0.0008499/1.167, allocations: 228.4 kB / 0.9296 GB, free: 8.93 MB / 0.7169 GB
Notification: Performance of preOpt evaluateParameters (simulation): time 0.001558/1.169, allocations: 1.111 MB / 0.9307 GB, free: 8.555 MB / 0.7169 GB
Notification: Performance of preOpt simplifyIfEquations (simulation): time 5.548e-05/1.169, allocations: 41.88 kB / 0.9307 GB, free: 8.551 MB / 0.7169 GB
Notification: Performance of preOpt expandDerOperator (simulation): time 0.000111/1.169, allocations: 63.53 kB / 0.9308 GB, free: 8.551 MB / 0.7169 GB
Notification: Performance of preOpt clockPartitioning (simulation): time 0.001268/1.17, allocations: 0.7517 MB / 0.9315 GB, free: 8.449 MB / 0.7169 GB
Notification: Performance of preOpt findStateOrder (simulation): time 2.061e-05/1.17, allocations: 4 kB / 0.9315 GB, free: 8.445 MB / 0.7169 GB
Notification: Performance of preOpt replaceEdgeChange (simulation): time 6.363e-05/1.171, allocations: 28.19 kB / 0.9315 GB, free: 8.441 MB / 0.7169 GB
Notification: Performance of preOpt inlineArrayEqn (simulation): time 2.967e-05/1.171, allocations: 16.97 kB / 0.9316 GB, free: 8.441 MB / 0.7169 GB
Notification: Performance of preOpt removeEqualRHS (simulation): time 0.001353/1.172, allocations: 0.7522 MB / 0.9323 GB, free: 8.434 MB / 0.7169 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 0.003529/1.175, allocations: 3.061 MB / 0.9353 GB, free: 7.328 MB / 0.7169 GB
Notification: Performance of preOpt comSubExp (simulation): time 0.001358/1.177, allocations: 0.773 MB / 0.936 GB, free: 7.293 MB / 0.7169 GB
Notification: Performance of preOpt resolveLoops (simulation): time 0.0005345/1.177, allocations: 336.9 kB / 0.9364 GB, free: 7.281 MB / 0.7169 GB
Notification: Performance of preOpt evalFunc (simulation): time 0.003249/1.181, allocations: 3.601 MB / 0.9399 GB, free: 4.254 MB / 0.7169 GB
Notification: Performance of preOpt encapsulateWhenConditions (simulation): time 0.0006534/1.181, allocations: 387.5 kB / 0.9402 GB, free: 4.195 MB / 0.7169 GB
Notification: Performance of pre-optimization done (n=52): time 2.595e-06/1.181, allocations: 0 / 0.9402 GB, free: 4.195 MB / 0.7169 GB
Notification: Performance of matching and sorting (n=52): time 0.004897/1.186, allocations: 1.509 MB / 0.9417 GB, free: 3.973 MB / 0.7169 GB
Notification: Performance of inlineWhenForInitialization (initialization): time 4.816e-05/1.186, allocations: 92.17 kB / 0.9418 GB, free: 3.879 MB / 0.7169 GB
Notification: Performance of selectInitializationVariablesDAE (initialization): time 0.001347/1.188, allocations: 1.154 MB / 0.9429 GB, free: 3.719 MB / 0.7169 GB
Notification: Performance of collectPreVariables (initialization): time 5.818e-05/1.188, allocations: 40.55 kB / 0.943 GB, free: 3.688 MB / 0.7169 GB
Notification: Performance of collectInitialEqns (initialization): time 0.0003292/1.188, allocations: 495.3 kB / 0.9434 GB, free: 3.527 MB / 0.7169 GB
Notification: Performance of collectInitialBindings (initialization): time 0.0001222/1.188, allocations: 184.9 kB / 0.9436 GB, free: 3.418 MB / 0.7169 GB
Notification: Performance of simplifyInitialFunctions (initialization): time 8.696e-05/1.188, allocations: 62.23 kB / 0.9437 GB, free: 3.402 MB / 0.7169 GB
Notification: Performance of setup shared object (initialization): time 7.048e-05/1.188, allocations: 329 kB / 0.944 GB, free: 3.098 MB / 0.7169 GB
Notification: Performance of preBalanceInitialSystem (initialization): time 0.0005328/1.189, allocations: 314.4 kB / 0.9443 GB, free: 3.098 MB / 0.7169 GB
Notification: Performance of partitionIndependentBlocks (initialization): time 0.0007253/1.19, allocations: 0.5992 MB / 0.9449 GB, free: 2.945 MB / 0.7169 GB
Notification: Performance of analyzeInitialSystem (initialization): time 0.001116/1.191, allocations: 0.721 MB / 0.9456 GB, free: 2.844 MB / 0.7169 GB
Notification: Performance of solveInitialSystemEqSystem (initialization): time 3.366e-06/1.191, allocations: 0 / 0.9456 GB, free: 2.844 MB / 0.7169 GB
Notification: Performance of matching and sorting (n=81) (initialization): time 0.001806/1.193, allocations: 1.004 MB / 0.9466 GB, free: 2.715 MB / 0.7169 GB
Notification: Performance of prepare postOptimizeDAE: time 6.81e-05/1.193, allocations: 166.8 kB / 0.9467 GB, free: 2.543 MB / 0.7169 GB
Notification: Performance of postOpt simplifyComplexFunction (initialization): time 8.766e-06/1.193, allocations: 2.688 kB / 0.9467 GB, free: 2.543 MB / 0.7169 GB
Notification: Performance of postOpt tearingSystem (initialization): time 1.242/2.435, allocations: 193.5 MB / 1.136 GB, free: 5.871 MB / 0.8887 GB
Notification: Performance of postOpt solveSimpleEquations (initialization): time 0.0006748/2.436, allocations: 130.3 kB / 1.136 GB, free: 5.758 MB / 0.8887 GB
Notification: Performance of postOpt calculateStrongComponentJacobians (initialization): time 0.001443/2.437, allocations: 1.292 MB / 1.137 GB, free: 4.5 MB / 0.8887 GB
Notification: Performance of postOpt simplifyAllExpressions (initialization): time 0.001214/2.439, allocations: 98.69 kB / 1.137 GB, free: 4.414 MB / 0.8887 GB
Notification: Performance of postOpt collapseArrayExpressions (initialization): time 0.0001385/2.439, allocations: 31.36 kB / 1.137 GB, free: 4.391 MB / 0.8887 GB
Notification: Performance of prepare postOptimizeDAE: time 1.161e-05/2.439, allocations: 4 kB / 1.137 GB, free: 4.387 MB / 0.8887 GB
Notification: Performance of postOpt replaceHomotopyWithSimplified (initialization): time 0.00198/2.441, allocations: 0.8797 MB / 1.138 GB, free: 3.789 MB / 0.8887 GB
Notification: Performance of postOpt simplifyComplexFunction (initialization): time 8.876e-06/2.441, allocations: 4 kB / 1.138 GB, free: 3.785 MB / 0.8887 GB
Notification: Performance of postOpt tearingSystem (initialization): time 1.613/4.054, allocations: 193.5 MB / 1.327 GB, free: 432.5 MB / 1.014 GB
Notification: Performance of postOpt solveSimpleEquations (initialization): time 0.0006079/4.055, allocations: 135.7 kB / 1.327 GB, free: 432.4 MB / 1.014 GB
Notification: Performance of postOpt calculateStrongComponentJacobians (initialization): time 0.00124/4.056, allocations: 1.282 MB / 1.328 GB, free: 431.1 MB / 1.014 GB
Notification: Performance of postOpt simplifyAllExpressions (initialization): time 0.001233/4.057, allocations: 98.92 kB / 1.329 GB, free: 431.1 MB / 1.014 GB
Notification: Performance of postOpt collapseArrayExpressions (initialization): time 0.0001651/4.058, allocations: 32.42 kB / 1.329 GB, free: 431 MB / 1.014 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 ($PRE.datRea.nextTimeEvent,$whenCondition1,datRea.nextTimeEventScaled,$PRE.datRea.nextTimeEventScaled,datRea.nextTimeEvent)
 * Number of discrete states: 0 ()
 * Number of clocked states: 0 ()
 * Top-level inputs: 0
Notification: Strong component statistics for initialization (74):
 * Single equations (assignments): 72
 * Array equations: 0
 * Algorithm blocks: 0
 * Record equations: 0
 * When equations: 0
 * If-equations: 0
 * Equation systems (not torn): 0
 * Torn equation systems: 2
 * Mixed (continuous/discrete) equation systems: 0
Notification: Torn system details for strict tearing set:
 * Linear torn systems (#iteration vars, #inner vars, density): 0 systems
 * Non-linear torn systems (#iteration vars, #inner vars): 2 systems
   {(1,6), (1,1)}
Notification: Performance of prepare postOptimizeDAE: time 0.0007596/4.058, allocations: 371.4 kB / 1.329 GB, free: 430.8 MB / 1.014 GB
Notification: Performance of postOpt lateInlineFunction (simulation): time 0.000315/4.059, allocations: 107.6 kB / 1.329 GB, free: 430.7 MB / 1.014 GB
Notification: Performance of postOpt wrapFunctionCalls (simulation): time 0.002171/4.061, allocations: 0.9592 MB / 1.33 GB, free: 430 MB / 1.014 GB
Notification: Performance of postOpt inlineArrayEqn (simulation): time 1.63e-05/4.061, allocations: 11.36 kB / 1.33 GB, free: 430 MB / 1.014 GB
Notification: Performance of postOpt constantLinearSystem (simulation): time 8.426e-06/4.061, allocations: 0 / 1.33 GB, free: 430 MB / 1.014 GB
Notification: Performance of postOpt simplifysemiLinear (simulation): time 0.001405/4.062, allocations: 0.9939 MB / 1.331 GB, free: 429.1 MB / 1.014 GB
Notification: Performance of postOpt removeSimpleEquations (simulation): time 0.004438/4.067, allocations: 2.092 MB / 1.333 GB, free: 427 MB / 1.014 GB
Notification: Performance of postOpt simplifyComplexFunction (simulation): time 6.482e-06/4.067, allocations: 3.984 kB / 1.333 GB, free: 427 MB / 1.014 GB
Notification: Performance of postOpt solveSimpleEquations (simulation): time 0.000318/4.067, allocations: 83.28 kB / 1.333 GB, free: 426.9 MB / 1.014 GB
Notification: Performance of postOpt tearingSystem (simulation): time 0.5872/4.654, allocations: 96.84 MB / 1.428 GB, free: 330 MB / 1.014 GB
Notification: Performance of postOpt inputDerivativesUsed (simulation): time 0.0001987/4.655, allocations: 19.98 kB / 1.428 GB, free: 330 MB / 1.014 GB
Notification: Performance of postOpt calculateStrongComponentJacobians (simulation): time 0.001017/4.656, allocations: 0.7439 MB / 1.428 GB, free: 329.2 MB / 1.014 GB
Notification: Performance of postOpt calculateStateSetsJacobians (simulation): time 4.859e-06/4.656, allocations: 6.016 kB / 1.428 GB, free: 329.2 MB / 1.014 GB
Notification: Performance of postOpt symbolicJacobian (simulation): time 0.004/4.66, allocations: 1.512 MB / 1.43 GB, free: 327.7 MB / 1.014 GB
Notification: Performance of postOpt removeConstants (simulation): time 0.0006589/4.66, allocations: 293.5 kB / 1.43 GB, free: 327.4 MB / 1.014 GB
Notification: Performance of postOpt simplifyTimeIndepFuncCalls (simulation): time 0.0003236/4.661, allocations: 12 kB / 1.43 GB, free: 327.4 MB / 1.014 GB
Notification: Performance of postOpt simplifyAllExpressions (simulation): time 0.0008119/4.661, allocations: 53.42 kB / 1.43 GB, free: 327.4 MB / 1.014 GB
Notification: Performance of postOpt findZeroCrossings (simulation): time 0.000116/4.662, allocations: 40.38 kB / 1.43 GB, free: 327.3 MB / 1.014 GB
Notification: Performance of postOpt collapseArrayExpressions (simulation): time 8.794e-05/4.662, allocations: 23.98 kB / 1.43 GB, free: 327.3 MB / 1.014 GB
Notification: Performance of sorting global known variables: time 0.001332/4.663, allocations: 0.8088 MB / 1.431 GB, free: 326.5 MB / 1.014 GB
Notification: Performance of sort global known variables: time 1.51e-07/4.663, allocations: 0 / 1.431 GB, free: 326.5 MB / 1.014 GB
Notification: Performance of remove unused functions: time 0.002987/4.666, allocations: 0.7144 MB / 1.432 GB, free: 325.9 MB / 1.014 GB
Notification: Model statistics after passing the back-end for simulation:
 * Number of independent subsystems: 4
 * Number of states: 1 (tow.vol.dynBal.U)
 * Number of discrete variables: 3 ($whenCondition1,datRea.nextTimeEvent,datRea.nextTimeEventScaled)
 * Number of discrete states: 2 (datRea.nextTimeEvent,datRea.nextTimeEventScaled)
 * Number of clocked states: 0 ()
 * Top-level inputs: 0
Notification: Strong component statistics for simulation (50):
 * Single equations (assignments): 44
 * Array equations: 0
 * Algorithm blocks: 0
 * Record equations: 3
 * When equations: 2
 * If-equations: 0
 * Equation systems (not torn): 0
 * Torn equation systems: 1
 * Mixed (continuous/discrete) equation systems: 0
Notification: Torn system details for strict tearing set:
 * Linear torn systems (#iteration vars, #inner vars, density): 0 systems
 * Non-linear torn systems (#iteration vars, #inner vars): 1 system
   {(1,6)}
Notification: Performance of Backend phase and start with SimCode phase: time 0.003063/4.669, allocations: 0.9264 MB / 1.433 GB, free: 325.2 MB / 1.014 GB
Notification: Performance of simCode: created initialization part: time 0.002607/4.672, allocations: 1.209 MB / 1.434 GB, free: 324 MB / 1.014 GB
Notification: Performance of simCode: created event and clocks part: time 7.945e-06/4.672, allocations: 0 / 1.434 GB, free: 324 MB / 1.014 GB
Notification: Performance of simCode: created simulation system equations: time 0.000707/4.672, allocations: 386.7 kB / 1.434 GB, free: 323.7 MB / 1.014 GB
Notification: Performance of simCode: created of all other equations (e.g. parameter, nominal, assert, etc): time 0.002903/4.675, allocations: 476 kB / 1.435 GB, free: 323.2 MB / 1.014 GB
Notification: Performance of simCode: created linear, non-linear and system jacobian parts: time 0.003591/4.679, allocations: 2.39 MB / 1.437 GB, free: 320.8 MB / 1.014 GB
Notification: Performance of simCode: some other stuff during SimCode phase: time 0.0006642/4.68, allocations: 1.088 MB / 1.438 GB, free: 319.7 MB / 1.014 GB
Notification: Performance of simCode: alias equations: time 0.001033/4.681, allocations: 274.3 kB / 1.438 GB, free: 319.4 MB / 1.014 GB
Notification: Performance of simCode: all other stuff during SimCode phase: time 0.0002569/4.681, allocations: 99.34 kB / 1.438 GB, free: 319.3 MB / 1.014 GB
Notification: Performance of SimCode: time 1.122e-06/4.681, allocations: 0 / 1.438 GB, free: 319.3 MB / 1.014 GB
Notification: Performance of Templates: time 0.04103/4.722, allocations: 26.34 MB / 1.464 GB, free: 293.3 MB / 1.014 GB
make -j1 -f Buildings_maint.7.0.x_Buildings.Fluid.HeatExchangers.CoolingTowers.Validation.MerkelEnergyPlus.makefile
Environment - environmentSimulation:
(rm -f Buildings_maint.7.0.x_Buildings.Fluid.HeatExchangers.CoolingTowers.Validation.MerkelEnergyPlus.pipe ; mkfifo Buildings_maint.7.0.x_Buildings.Fluid.HeatExchangers.CoolingTowers.Validation.MerkelEnergyPlus.pipe ; head -c 1048576 < Buildings_maint.7.0.x_Buildings.Fluid.HeatExchangers.CoolingTowers.Validation.MerkelEnergyPlus.pipe >> ../files/Buildings_maint.7.0.x_Buildings.Fluid.HeatExchangers.CoolingTowers.Validation.MerkelEnergyPlus.sim & ./Buildings_maint.7.0.x_Buildings.Fluid.HeatExchangers.CoolingTowers.Validation.MerkelEnergyPlus  -abortSlowSimulation -alarm=480 -lv LOG_STATS > Buildings_maint.7.0.x_Buildings.Fluid.HeatExchangers.CoolingTowers.Validation.MerkelEnergyPlus.pipe 2>&1)
Environment - environmentSimulation: