<div dir="ltr"><br clear="all"><div><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div dir="ltr"><br></div><div>Please note the chance of time and place</div></div></div></div></div></div><div class="gmail_quote"><br> <div class="m_2957682826981837134F0XO1GC-nb-gb"><div class="m_2957682826981837134F0XO1GC-I-d"><input style="opacity:0;height:1px;width:1px;overflow:hidden" type="text"><span></span></div></div> <div class="m_2957682826981837134F0XO1GC-ed-a"> <div class="m_2957682826981837134F0XO1GC-nb-P"><input style="opacity:0;height:1px;width:1px;overflow:hidden" type="text"><div><div style="overflow:auto"><div style="max-height:10000px"><div dir="ltr"><div><div style="overflow:auto"><div style="max-height:10000px"><div dir="ltr"><div><div style="overflow:auto"><div style="max-height:10000px"><div dir="ltr"><div><div style="overflow:auto"><div style="max-height:10000px"><div dir="ltr"><div><div style="overflow:auto"><div style="max-height:10000px"><div dir="ltr"><p style="text-align:center;clear:both"><a href="https://lh3.googleusercontent.com/-ZPFNPh16sR0/Wt39FrXUP-I/AAAAAAAAAaw/3wQunGe20lUopmV_ggfPaDwE9cVAgVzxgCLcBGAs/s1600/image001.jpg" style="margin-left:1em;margin-right:1em" target="_blank"><img src="https://lh3.googleusercontent.com/-ZPFNPh16sR0/Wt39FrXUP-I/AAAAAAAAAaw/3wQunGe20lUopmV_ggfPaDwE9cVAgVzxgCLcBGAs/s1600/image001.jpg" border="0"></a></p><br>
<p class="MsoNormal" style="text-align:center" align="center"><span style="font-family:"Verdana",sans-serif;color:black">DATE:</span><span style="font-size:10.0pt;font-family:"Verdana",sans-serif;color:black"> </span><span style="font-size:13.5pt;font-family:"Verdana",sans-serif;color:black"> </span><b><span style="font-size:18.0pt;font-family:"Verdana",sans-serif">Friday, May 10, 2019</span></b></p>
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<p class="MsoNormal" style="text-align:center" align="center"><span style="font-family:"Verdana",sans-serif;color:black">TITLE:</span><span style="font-size:10.0pt;font-family:"Verdana",sans-serif;color:black"> <br></span></p><p class="MsoNormal" style="text-align:center" align="center"><span style="font-size:10.0pt;font-family:"Verdana",sans-serif;color:black"> <br></span></p><p class="MsoNormal" style="text-align:center" align="center"><font size="6"><span style="font-family:verdana,sans-serif"></span></font></p><p class="MsoNormal" style="text-align:center" align="center"><font size="6"><span style="font-family:verdana,sans-serif"><b><span style="background:white none repeat scroll 0% 0%"></span></b></span></font></p><div style="text-align:center"><span style="font-family:verdana,sans-serif"><font size="6"><b><span></span></b></font></span><span style="font-family:verdana,sans-serif"><font size="6"><b><span></span></b></font></span><span style="font-family:verdana,sans-serif"><font size="6"><b><span></span></b></font></span><span style="font-family:verdana,sans-serif"><font size="6"><b><span></span></b></font></span><span style="font-family:verdana,sans-serif"><font size="6"><b><span></span></b></font></span><span style="font-family:verdana,sans-serif"><font size="6"><b><span></span></b></font></span><span style="font-family:verdana,sans-serif"><font size="6"><b><span></span></b></font></span><span style="font-family:verdana,sans-serif"><font size="6"><b><span></span></b></font></span><span style="font-family:verdana,sans-serif"><font size="6"><b><span></span></b></font></span><span style="font-family:verdana,sans-serif"><font size="6"><b><span> </span></b></font></span><span style="font-family:verdana,sans-serif"><font size="6"><b><span></span></b></font></span><span style="font-family:verdana,sans-serif"><font size="6"><b><span></span></b></font></span><span style="font-family:verdana,sans-serif"><font size="6"><b><span><span class="m_2957682826981837134event-description">Quantifying Particle Departure from Axisymmetry in Multiphase Cylindrical Detonation</span> </span></b></font><br></span><span style="font-family:verdana,sans-serif"><font size="6"><b><span style="font-size:11pt"></span></b> </font></span></div><p class="MsoNormal" style="text-align:center" align="center"><span style="font-family:"Verdana",sans-serif;color:black"></span></p>
<p class="MsoNormal" style="text-align:center" align="center"><span style="font-family:"Verdana",sans-serif;color:black"><br></span></p><p class="MsoNormal" style="text-align:center" align="center"><span style="font-family:"Verdana",sans-serif;color:black">TIME:</span><span style="font-size:10.0pt;font-family:"Verdana",sans-serif;color:black"> </span><span style="font-size:13.5pt;font-family:"Verdana",sans-serif;color:black"> </span><b><span style="font-size:18.0pt;font-family:"Verdana",sans-serif">3<span style="color:black">:00PM</span></span></b></p>
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<p class="MsoNormal" style="text-align:center" align="center"><span style="font-family:"Verdana",sans-serif;color:black">LOCATION:</span><span style="font-size:10.0pt;font-family:"Verdana",sans-serif;color:black"> <b> </b></span><b><span style="font-size:18.0pt;font-family:"Verdana",sans-serif">Donald P. Shiley Bioscience Center Auditorium<br></span></b></p>
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<p class="MsoNormal" style="text-align:center" align="center"><span style="font-family:"Verdana",sans-serif;color:black">SPEAKER/BIO:</span><span style="font-size:13.5pt;font-family:"Verdana",sans-serif;color:black"> </span><b><span style="font-size:18.0pt;font-family:"Verdana",sans-serif"><br></span></b></p><p class="MsoNormal" style="text-align:center" align="center"><br><b><span style="font-size:18.0pt;font-family:"Verdana",sans-serif"></span></b></p><p class="MsoNormal" style="text-align:center" align="center"><b><span style="font-size:18.0pt;font-family:"Verdana",sans-serif"></span></b><b><span style="font-size:18.0pt;font-family:"Verdana",sans-serif"></span></b><b><span style="font-size:18.0pt;font-family:"Verdana",sans-serif"></span></b><b><span style="font-size:18.0pt;font-family:"Verdana",sans-serif">Dr.</span><span style="font-size:18.0pt;font-family:"Verdana",sans-serif"> </span></b><b><span style="font-size:18.0pt;font-family:"Verdana",sans-serif"></span></b><b><span style="font-size:18.0pt;font-family:"Verdana",sans-serif">M. Giselle Fernandez, Posdoctoral Researcher,</span></b></p><p class="MsoNormal" style="text-align:center" align="center"><b><span style="font-size:18.0pt;font-family:"Verdana",sans-serif">Los Alamos National Laboratory<br></span></b><font size="4"><span style="font-family:verdana,sans-serif"><b><span><b><span style="font-size:18.0pt;font-family:"Verdana",sans-serif"><span style="color:black"></span></span></b></span><span></span></b></span></font></p><p class="MsoNormal" style="text-align:center" align="center"><b><span style="font-size:18.0pt;font-family:"Verdana",sans-serif"></span></b></p>
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<p class="MsoNormal"><span style="font-family:"Verdana",sans-serif;color:black"><br></span></p><p class="MsoNormal"><span style="font-family:"Verdana",sans-serif;color:black">ABSTRACT:</span></p><font size="4"><span style="font-family:verdana,sans-serif"><span class="m_2957682826981837134event-description">Dense layers of solid particles surrounding a high-energy explosive generate instabilities after detonation. Conjectures as to the cause of these instabilities include imperfections in the casing, inhomogeneities in the initial distribution of particles, characteristics of the particles, and others. In particular, a multiphase detonation with a cylindrical configuration where the initial distribution of particles is initially highly axisymmetric is studied. The main physical mechanism responsible for the instabilities observed in the experiments is assumed to be the initial distribution of particles. Therefore, the particle volume is perturbed in the simulations using azimuthal sinusoidal waves and the final distribution of the particles is observed quantifying the amplification of the departure from axisymmetry. <br></span></span></font></div><div dir="ltr"><font size="4"><span style="font-family:verdana,sans-serif"><span class="m_2957682826981837134event-description"><br></span></span></font></div><div dir="ltr"><font size="4"><span style="font-family:verdana,sans-serif"><span class="m_2957682826981837134event-description">An instability mechanism, that is possibly partially the result of non-classical Raleigh-Taylor and/or Richmyer-Meshkov instabilities, is observed. We have called it channeling instability and it has two main effects (i) accelerate particles located in low particle volume radial sectors and (ii) push particles from low particle volume sectors to high particle volume sectors.</span></span></font></div><div dir="ltr"><font size="4"><span style="font-family:verdana,sans-serif"><span class="m_2957682826981837134event-description"><br></span></span></font></div><div dir="ltr"><font size="4"><span style="font-family:verdana,sans-serif"><span class="m_2957682826981837134event-description">
To quantify the particles departure from axisymmetry, a metric based on energy is constructed, which depends on the parameters of a trimodal sinusoidal perturbation (amplitudes, wavelengths, and relative phases). The metric dependence on the relative phases was found to be negligible and unimodal perturbations were found to amplify the metric the most. <br></span></span></font></div><div dir="ltr"><font size="4"><span style="font-family:verdana,sans-serif"><span class="m_2957682826981837134event-description"><br></span></span></font></div><div dir="ltr"><font size="4"><span style="font-family:verdana,sans-serif"><span class="m_2957682826981837134event-description">
The simulations considered are expensive and surrogate models can achieve accurate predictions of the metric dependence on the amplitudes and the wavelengths at a low computational cost. Linear regression is used to construct low-fidelity, high-fidelity, and multi-fidelity surrogate models. It was found that for this problem with this particular surrogate and basis functions, multi-fidelity models have better performance compared with single-fidelity models. <br></span></span></font></div><div dir="ltr"><font size="4"><span style="font-family:verdana,sans-serif"><span class="m_2957682826981837134event-description"><br></span></span></font></div><div dir="ltr"><font size="4"><span style="font-family:verdana,sans-serif"><span class="m_2957682826981837134event-description">
Options for reducing the number of simulation used to construct surrogates while maintaining accuracy by taking advantage of parametric symmetries were also explored. The inherent parametric symmetries of the model were imposed while building the multi-fidelity surrogate and the performance compared with the multi-fidelity surrogate without imposing symmetries. For a small number of high-fidelity points it was found that the performance of the surrogate using symmetries is much better, however, for more than 100 HF data points their performance is indistinguishable.
</span></span></font></div><div dir="ltr"><font size="4"><span style="font-family:verdana,sans-serif"><br></span></font></div><div dir="ltr"><font size="2"><span style="font-family:verdana,sans-serif"><span style="font-family:"Verdana",sans-serif;color:black"></span></span></font></div><br><div dir="ltr"><br><font size="4"><span style="font-family:verdana,sans-serif"></span><span style="font-family:verdana,sans-serif"></span></font></div><div dir="ltr"><font size="4"><span style="font-family:verdana,sans-serif">Host: Satchi Venkataraman<br></span></font></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div><table class="m_2957682826981837134F0XO1GC-nb-O" cellspacing="0" cellpadding="0"><tbody><tr><td class="m_2957682826981837134F0XO1GC-nb-R" valign="top" align="left"><span class="m_2957682826981837134_username"><span class="m_2957682826981837134F0XO1GC-F-a" style="color:rgb(34,34,34)"></span></span> <span></span> </td> <td valign="top" align="right"> <div class="m_2957682826981837134F0XO1GC-nb-e"><div class="m_2957682826981837134F0XO1GC-m-a m_2957682826981837134jfk-button-standard m_2957682826981837134F0XO1GC-m-g m_2957682826981837134F0XO1GC-nb-i m_2957682826981837134F0XO1GC-nb-A"><img src="cid:autoGeneratedInlineImage1" class="m_2957682826981837134gwt-Image m_2957682826981837134F0XO1GC-m-e" width="21" height="21"><input style="opacity:0;height:1px;width:1px;overflow:hidden" type="text"><span class="m_2957682826981837134F0XO1GC-m-f"></span></div><span class="m_2957682826981837134F0XO1GC-nb-i m_2957682826981837134F0XO1GC-nb-f"><div class="m_2957682826981837134F0XO1GC-m-a m_2957682826981837134jfk-button-standard m_2957682826981837134F0XO1GC-k-c m_2957682826981837134F0XO1GC-nb-k m_2957682826981837134F0XO1GC-m-j m_2957682826981837134F0XO1GC-m-i" id="m_2957682826981837134b_action_opWQHuptAwAJ"><input style="opacity:0;height:1px;width:1px;overflow:hidden" type="text"><span class="m_2957682826981837134F0XO1GC-m-f"><span></span></span><span class="m_2957682826981837134F0XO1GC-k-a"><span class="m_2957682826981837134F0XO1GC-k-b"></span></span></div></span></div> <div class="m_2957682826981837134F0XO1GC-nb-R m_2957682826981837134F0XO1GC-nb-T"> <span class="m_2957682826981837134F0XO1GC-nb-Q m_2957682826981837134F0XO1GC-b-Fb" title="Thursday, May 2, 2019 at 8:23:26 AM UTC-7">May 2</span> </div> </td> </tr> </tbody></table>
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