Photo of Samuel Grauer

232 Research East
Penn State
+1 (814) 863-6289

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I am currently an Assistant Professor in the Department of Mechanical Engineering at Penn State. My research is focused on inverse problems in mechanical engineering. The aim of this work is to obtain reliable measurements of complex systems (featuring, e.g., advanced forms of combustion, high-speed flows, or disparate-viscosity mixing) in order to understand the underlying physics and ultimately improve the system's design. In particular, I use a statistical (Bayesian) approach to: (i) develop algorithms for 3D fluid flow and combustion imaging, (ii) use spectroscopic post-processing to extract useful information from laser absorption/hyperspectral imaging data, and (iii) combine measurements from multiple experiments (e.g., different regimes of laser-induced incandescence) to infer fundamental properties of the target (e.g., the change in a nanoparticle's latent heat of vaporization with increasing temperature). Some relevant buzz words: tomography, ill-posed inverse problems, sensor fusion, data assimilation, uncertainty quantification, optimal design-of-experiments, model selection.

I received a PhD from the University of Waterloo in September 2018, and a BSc in Mechanical Engineering from the University of Manitoba in 2014. From 2018 to 2020, I was a postdoc in the Ben T. Zinn Combustion Lab at the Georgia Institute of Technology.

Curriculum Vitae – You can find a somewhat recent copy of my CV here.

Prospective Students

If you are an aspiring PhD student, gifted in the areas of programming, applied physics, and/or statistics, having a penchant for tinkering with laser beams and high-speed cameras, and posessing an unquenchable thirst for knowledge and interest in problems that lie at the junction of physics, measurement, and uncertainty... then please do send me an email.


  1. Brown, N.P., S.J. Grauer, S.J., J.A. Deibel, M.L.R. Walker, and A.M. Steinberg, "Bayesian framework for THz-TDS plasma diagnostics," Opt. Express 29(4), 4887-4901 (2021) doi: 10.1364/OE.417396
  2. Grauer, S.J., and A.M. Steinberg, "Linear absorption tomography with velocimetry (LATV) for multiparameter measurements in high-speed flows," Opt. Express 28(22), 32676-32692 (2020) doi: 10.1364/OE.408588
  3. Miguel, R.B., J. Emmert, S.J. Grauer, J.N. Thornock, and K.J. Daun, "Optimal filter selection for quantitative gas mixture imaging," J. Quantit. Spectrosc. Radiat. Transfer 254, 107208 (2020) doi: 10.1016/j.jqsrt.2020.107208
  4. Grauer, S.J., and A.M. Steinberg, "Fast and robust volumetric refractive index measurement by unified background-oriented schlieren tomography," Exp. Fluids 61, 80 (2020) doi: 10.1007/s00348-020-2912-1
  5. Emmert, J., S.J. Grauer, S. Wagner, and K.J. Daun, "Efficient Bayesian inference of absorbance spectra from transmitted intensity spectra," Opt. Express 27(19), 26893-26909 (2019) doi: 10.1364/OE.27.026893
  6. Grauer, S.J., J. Emmert, S.T. Sanders, S. Wagner, and K.J. Daun, "Multiparameter gas sensing with linear hyperspectral absorption tomography," Meas. Sci. Technol. 30(10), 105401 (2019) doi: 10.1088/1361-6501/ab274b
  7. Grauer, S.J., A. Unterberger, A. Rittler, K.J. Daun, A.M. Kempf, and K. Mohri, "Instantaneous 3D flame imaging by background-oriented schlieren tomography," Combust. Flame 196, 284-299 (2018) doi: 10.1016/j.combustflame.2018.06.022
  8. Sipkens, T.A., P.J. Hadwin, S.J. Grauer, and K.J. Daun, "Predicting the heat of vaporization of iron at high temperatures using time-resolved laser-induced incandescence and Bayesian model selection," J. Appl. Phys. 123(9), 095103 (2018) doi: 10.1063/1.5016341
  9. Grauer, S.J., B.C. Conrad, R.B. Miguel, and K.J. Daun, "Gaussian model for emission rate measurement of a heated plume using hyperspectral data," J. Quantit. Spectrosc. Radiat. Transfer 206, 125-134 (2018) doi: 10.1016/j.jqsrt.2017.11.005
  10. Sipkens, T.A., P.J. Hadwin, S.J. Grauer, and K.J. Daun, "General error model for analysis of laser-induced incandescence signals," Appl. Opt. 56(30), 8436-8445 (2017) doi: 10.1364/AO.56.008436
  11. Grauer, S.J., P.J. Hadwin, T.A. Sipkens, K.J. Daun, "Measurement-based meshing, basis selection, and prior assignment in chemical species tomography," Opt. Express 25(21), 25135-25148 (2017) doi: 10.1364/OE.25.025135
  12. Grauer, S.J., R.W. Tsang, and K.J. Daun, "Broadband chemical species tomography: Measurement theory and a proof-of-concept emission detection experiment," J. Quant. Spectrosc. Radiat. Transfer 198, 145-154 (2017) doi: 10.1016/j.jqsrt.2017.04.030
  13. Grauer, S.J., P.J. Hadwin, and K.J. Daun, "Improving chemical species tomography of turbulent flows using covariance estimation," Appl. Opt. 56(13), 3900-3912 (2017) doi: 10.1364/AO.56.003900
  14. Grauer, S.J., P.J. Hadwin, and K.J. Daun, "Bayesian approach to the design of chemical species tomography experiments," Appl. Opt. 55(21), 5772-5782 (2016) doi: 10.1364/AO.55.005772
  15. Daun, K.J., S.J. Grauer, and P.J. Hadwin, "Chemical species tomography of turbulent flows: Discrete ill-posed and rank deficient problems and the use of prior information," J. Quant. Spectrosc. Radiat. Transfer 172, 58-74 (2016) doi: 10.1016/j.jqsrt.2015.09.011
  16. Grauer, S.J., E.J.F.R. Caron, N.L. Chester, M.A. Wells, and K.J. Daun, "Investigation of melting in the Al–Si coating of a boron steel sheet by differential scanning calorimetry," J. Mater. Process. Technol. 216, 89-94 (2015) doi: 10.1016/j.jmatprotec.2014.09.001


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