Generation of Nyquist plots from the model "ac_fuel_cell" in FEMLAB There are several ways to generate Nyquist plots, i.e. -Im(Z) vs. Re(Z), in FEMLAB. If you only need to do it once or a few times I would recommend the following procedure. If you intend to do it repeatedly (for example if you wish to vary parameters), I recommend you to save the FEMLAB model as a MATLAB m-file, edit it to produce the plot and run it from within MATLAB. The Nyquist plot is generated from within MATLAB (or any other graph-drawing program), based on the exported ASCII results of the FEMLAB model. Follow these steps: 1. Open and Run the impedance model (the model uses a Boundary Expression to generate ReZ=Real(Z) and ImZ=-Imag(Z) from the complex valued results of the model. 2. Produce a Domain Plot>Point plot>Expression: ReZ, Point:1 3. In the General Tab of the Domain Plot dialog box, check Keep current plot. 4. Then also point-plot (point 1) the expression: ImZ. 5. In the figure window, click the ASCII button to export the data as text. 6. Open the generated text-file and copy the first block of data (2 columns and 100 rows). 7. Open MATLAB(or any other Graph-drawing program). 8. Copy the data from the text file to the Graph-program, and create the plot of -ImZ vs. ReZ. Plotting using MATLAB: 1. Open MATLAB and create the matrix A=[pasted text]; 2. Copy and paste the second block of data as the matrix B. 3. Now, A=[w,ReZ], and B=[w,ImZ]; 4. The MATLAB command "plot(A(:,2),-B(:,2),'*-')" results in the Nyquist plot as depicted in the PDF-document of the model "ac_fuel_cell". MATLAB Command history: » A=[1.0E-4 1.5524102E-4 1.2618568E-4 1.5524102E-4 1.5922828E-4 1.5524102E-4 2.009233E-4 1.5524102E-4 2.5353645E-4 1.5524102E-4 3.199267E-4 1.5524102E-4 4.0370174E-4 1.5524102E-4 5.094138E-4 1.5524102E-4 6.4280734E-4 1.5524102E-4 8.1113086E-4 1.5524102E-4 0.0010235311 1.5524102E-4 0.0012915496 1.5524102E-4 0.0016297508 1.5524102E-4 0.0020565123 1.5524102E-4 0.0025950242 1.5524102E-4 0.0032745493 1.5524102E-4 0.0041320124 1.5524102E-4 0.0052140085 1.5524102E-4 0.006579332 1.5524102E-4 0.008302175 1.5524102E-4 0.010476157 1.5524102E-4 0.0132194115 1.5524102E-4 0.016681006 1.5524102E-4 0.021049041 1.5524102E-4 0.026560878 1.5524102E-4 0.033516027 1.5524102E-4 0.042292427 1.5524102E-4 0.053366993 1.5524102E-4 0.06734151 1.5524102E-4 0.08497535 1.5524102E-4 0.10722672 1.5524101E-4 0.13530478 1.5524101E-4 0.17073527 1.55241E-4 0.21544346 1.5524098E-4 0.2718588 1.5524095E-4 0.34304693 1.5524092E-4 0.43287614 1.5524086E-4 0.5462277 1.5524076E-4 0.6892612 1.552406E-4 0.869749 1.5524036E-4 1.0974988 1.5523996E-4 1.3848864 1.5523934E-4 1.7475284 1.5523835E-4 2.2051308 1.5523676E-4 2.7825594 1.5523423E-4 3.5111918 1.552302E-4 4.4306216 1.552238E-4 5.5908103 1.552136E-4 7.0548024 1.5519737E-4 8.902151 1.5517152E-4 11.23324 1.5513044E-4 14.174742 1.550651E-4 17.886496 1.5496135E-4 22.570198 1.547968E-4 28.480358 1.5453644E-4 35.938137 1.5412601E-4 45.348785 1.534828E-4 57.223675 1.5248395E-4 72.20809 1.5095458E-4 91.11627 1.4866292E-4 114.9757 1.4533753E-4 145.08287 1.4072996E-4 183.07382 1.3473723E-4 231.01297 1.2754992E-4 291.5053 1.1971443E-4 367.83798 1.11994086E-4 464.15887 1.0507108E-4 585.7021 9.9299476E-5 739.0722 9.46636E-5 932.60333 9.0900816E-5 1176.812 8.7663175E-5 1484.9683 8.4644205E-5 1873.8174 8.16562E-5 2364.4895 7.8651574E-5 2983.6472 7.5679556E-5 3764.9358 7.280257E-5 4750.81 7.003606E-5 5994.8423 6.735369E-5 7564.6333 6.4734515E-5 9545.484 6.219673E-5 12045.035 5.978997E-5 15199.11 5.756469E-5 19179.104 5.5550787E-5 24201.283 5.375521E-5 30538.555 5.2168845E-5 38535.285 5.0773935E-5 48626.016 4.95495E-5 61359.074 4.8474634E-5 77426.37 4.7530062E-5 97700.99 4.669875E-5 123284.67 4.5965935E-5 155567.61 4.531893E-5 196304.06 4.4746892E-5 247707.64 4.4240507E-5 312571.6 4.3791777E-5 394420.6 4.3393786E-5 497702.34 4.3040545E-5 628029.1 4.2726835E-5 792482.9 4.2448104E-5 1000000.0 4.220035E-5]; » B=[1.0E-4 -2.5196787E-11 1.2618568E-4 -3.1791663E-11 1.5922828E-4 -4.0116646E-11 2.009233E-4 -5.062484E-11 2.5353645E-4 -6.387709E-11 3.199267E-4 -8.0604926E-11 4.0370174E-4 -1.0171387E-10 5.094138E-4 -1.2834775E-10 6.4280734E-4 -1.6195592E-10 8.1113086E-4 -2.0436534E-10 0.0010235311 -2.578777E-10 0.0012915496 -3.2540398E-10 0.0016297508 -4.106161E-10 0.0020565123 -5.1813603E-10 0.0025950242 -6.538161E-10 0.0032745493 -8.25022E-10 0.0041320124 -1.0410611E-9 0.0052140085 -1.3136677E-9 0.006579332 -1.6576626E-9 0.008302175 -2.0917308E-9 0.010476157 -2.6394653E-9 0.0132194115 -3.3306256E-9 0.016681006 -4.2027732E-9 0.021049041 -5.303298E-9 0.026560878 -6.6920043E-9 0.033516027 -8.444354E-9 0.042292427 -1.0655563E-8 0.053366993 -1.34458E-8 0.06734151 -1.6966672E-8 0.08497535 -2.140951E-8 0.10722672 -2.7015735E-8 0.13530478 -3.408999E-8 0.17073527 -4.301668E-8 0.21544346 -5.4280886E-8 0.2718588 -6.8494685E-8 0.34304693 -8.643044E-8 0.43287614 -1.0906275E-7 0.5462277 -1.3762138E-7 0.6892612 -1.7365811E-7 0.869749 -2.1913092E-7 1.0974988 -2.765103E-7 1.3848864 -3.4891332E-7 1.7475284 -4.4027237E-7 2.2051308 -5.555481E-7 2.7825594 -7.009969E-7 3.5111918 -8.8450696E-7 4.4306216 -1.116019E-6 5.5908103 -1.408051E-6 7.0548024 -1.7763466E-6 8.902151 -2.2406675E-6 11.23324 -2.8257402E-6 14.174742 -3.5623468E-6 17.886496 -4.4884923E-6 22.570198 -5.6504673E-6 28.480358 -7.1033924E-6 35.938137 -8.91038E-6 45.348785 -1.1138652E-5 57.223675 -1.38497035E-5 72.20809 -1.7079023E-5 91.11627 -2.0800213E-5 114.9757 -2.487223E-5 145.08287 -2.8983459E-5 183.07382 -3.263608E-5 231.01297 -3.5237E-5 291.5053 -3.6318717E-5 367.83798 -3.578057E-5 464.15887 -3.395582E-5 585.7021 -3.143936E-5 739.0722 -2.8823019E-5 932.60333 -2.6514545E-5 1176.812 -2.4686753E-5 1484.9683 -2.3312914E-5 1873.8174 -2.2245147E-5 2364.4895 -2.1313028E-5 2983.6472 -2.0408617E-5 3764.9358 -1.9510917E-5 4750.81 -1.8641047E-5 5994.8423 -1.7800385E-5 7564.6333 -1.69502E-5 9545.484 -1.6039809E-5 12045.035 -1.5044174E-5 15199.11 -1.3975078E-5 19179.104 -1.2866693E-5 24201.283 -1.1757205E-5 30538.555 -1.06785565E-5 38535.285 -9.653316E-6 48626.016 -8.695148E-6 61359.074 -7.810703E-6 77426.37 -7.001689E-6 97700.99 -6.2665877E-6 123284.67 -5.6019226E-6 155567.61 -5.0031394E-6 196304.06 -4.4651856E-6 247707.64 -3.9828824E-6 312571.6 -3.551157E-6 394420.6 -3.1651743E-6 497702.34 -2.8204104E-6 628029.1 -2.5126863E-6 792482.9 -2.238177E-6 1000000.0 -1.993406E-6]; » w=A(:,1); » ReZ=A(:,2); » ImZ=B(:,2); » plot(ReZ,-ImZ,'*-')