From svfleet at uw.edu Mon Oct 3 16:05:47 2022 From: svfleet at uw.edu (Samuel Van Fleet) Date: Thu Mar 7 20:17:34 2024 Subject: [Amath-seminars] Boeing Seminar October 6 Message-ID: Dear all, Our first Boeing Seminar will be this Thursday, October 6th at 4PM in Smith 205 featuring Professor Lexing Ying [web.stanford.edu] of Stanford University. The title of his abstract can be found below and in the poster attachment. *Title: *Correcting Convexity Bias *Abstract: *We consider the problem of estimating a function or functional of an unknown input when only noisy observations of the input are available. When the function is convex (or concave) near the unknown input, the naive estimator often incurs a significant bias. We propose new estimators based on bootstrap to reduce this convexity bias. Theoretical analysis are conducted to show that the proposed methods can strictly reduce the expected estimate error under mild conditions. They can serve as off-the-shelf tools for a wide range of problems, including optimization problems with random objective functions or constraints, functionals of probability distributions such as the entropy and the Wasserstein distance, and matrix functions such as inversion. Thank you, Sam Van Fleet -- Sam Van Fleet (he/him/his) Acting Instructor of Applied Mathematics Department of Applied Mathematics University of Washington Seattle WA 98195 -------------- next part -------------- An HTML attachment was scrubbed... URL: -------------- next part -------------- A non-text attachment was scrubbed... Name: Boeing Seminar October 6th.pdf Type: application/pdf Size: 1406277 bytes Desc: not available URL: From svfleet at uw.edu Wed Oct 5 14:43:31 2022 From: svfleet at uw.edu (Samuel Van Fleet) Date: Thu Mar 7 20:17:34 2024 Subject: [Amath-seminars] Reminder Boeing Seminar Tomorrow October 6 Message-ID: Dear all, This is a reminder that our first Boeing Seminar will be this Thursday, October 6th at 4PM in Smith 205 featuring Professor Lexing Ying [web.stanford.edu] of Stanford University. The title of his abstract can be found below and in the poster attachment. *Title: *Correcting Convexity Bias *Abstract: *We consider the problem of estimating a function or functional of an unknown input when only noisy observations of the input are available. When the function is convex (or concave) near the unknown input, the naive estimator often incurs a significant bias. We propose new estimators based on bootstrap to reduce this convexity bias. Theoretical analysis are conducted to show that the proposed methods can strictly reduce the expected estimate error under mild conditions. They can serve as off-the-shelf tools for a wide range of problems, including optimization problems with random objective functions or constraints, functionals of probability distributions such as the entropy and the Wasserstein distance, and matrix functions such as inversion. Thank you, Sam Van Fleet -- Sam Van Fleet (he/him/his) Acting Instructor of Applied Mathematics Department of Applied Mathematics University of Washington Seattle WA 98195 -------------- next part -------------- An HTML attachment was scrubbed... URL: -------------- next part -------------- A non-text attachment was scrubbed... Name: Boeing Seminar October 6th.pdf Type: application/pdf Size: 1406277 bytes Desc: not available URL: From arahman2 at uw.edu Mon Oct 24 16:00:32 2022 From: arahman2 at uw.edu (Amin Rahman) Date: Thu Mar 7 20:17:34 2024 Subject: [Amath-seminars] Boeing Colloquium Thursday, Oct. 27 Message-ID: Dear All, Our Boeing Colloquium this week, presented by Professor Sigal Gottlieb of University of Massachusetts at Dartmouth ( https://www.umassd.edu/cas/math/people/faculty-and-staff/sigal-gottlieb/), will be held on Thursday, Oct. 27, 2022, 4 ? 5 p.m. in Smith Hall 205. Title: Developing high order, efficient, and stable time-evolution methods using a time-filtering approach. Abstract: Time stepping methods are critical to the stability, accuracy, and efficiency of the numerical solution of partial differential equations. In many legacy codes, well-tested low-order time-stepping modules are difficult to change; however, their accuracy and efficiency properties may form a bottleneck. Time filtering has been used to enhance the order of accuracy (as well as other properties) of time-stepping methods in legacy codes. In this talk I will describe our recent work on time filtering methods for the Navier Stokes equations as well as other applications. A rigorous development of such methods requires an understanding of the effect of the modification of inputs and outputs on the accuracy, efficiency, and stability of the time-evolution method. In this talk, we show that time-filtering a given method can be seen as equivalent to generating a new general linear method (GLM). We use this GLM approach to develop an optimization routine that enables us to find new time-filtering methods with high order and efficient linear stability properties. In addition, understanding the dynamics of the errors allows us to combine the time-filtering GLM methods with the error inhibiting approach to produce a third order A-stable method based on alternating time-filtering of implicit Euler method. I will present our new methods and show their performance when tested on sample problems. Best regards, Amin -- Aminur (Amin) Rahman (He/him/his) Acting Instructor (postdoc) Department of Applied Mathematics http://faculty.washington.edu/arahman2 -------------- next part -------------- An HTML attachment was scrubbed... URL: From arahman2 at uw.edu Wed Oct 26 16:18:58 2022 From: arahman2 at uw.edu (Amin Rahman) Date: Thu Mar 7 20:17:34 2024 Subject: [Amath-seminars] Reminder: Boeing Colloquium Tomorrow Thursday, Oct. 27 Message-ID: Dear All, Just a reminder that our Boeing Colloquium this week, presented by Professor Sigal Gottlieb of University of Massachusetts at Dartmouth ( https://www.umassd.edu/cas/math/people/faculty-and-staff/sigal-gottlieb/), will be held Tomorrow, Thursday, Oct. 27, 2022, 4 ? 5 p.m. in Smith Hall 205. Title: Developing high order, efficient, and stable time-evolution methods using a time-filtering approach. Abstract: Time stepping methods are critical to the stability, accuracy, and efficiency of the numerical solution of partial differential equations. In many legacy codes, well-tested low-order time-stepping modules are difficult to change; however, their accuracy and efficiency properties may form a bottleneck. Time filtering has been used to enhance the order of accuracy (as well as other properties) of time-stepping methods in legacy codes. In this talk I will describe our recent work on time filtering methods for the Navier Stokes equations as well as other applications. A rigorous development of such methods requires an understanding of the effect of the modification of inputs and outputs on the accuracy, efficiency, and stability of the time-evolution method. In this talk, we show that time-filtering a given method can be seen as equivalent to generating a new general linear method (GLM). We use this GLM approach to develop an optimization routine that enables us to find new time-filtering methods with high order and efficient linear stability properties. In addition, understanding the dynamics of the errors allows us to combine the time-filtering GLM methods with the error inhibiting approach to produce a third order A-stable method based on alternating time-filtering of implicit Euler method. I will present our new methods and show their performance when tested on sample problems. Best regards, Amin -- Aminur (Amin) Rahman (He/him/his) Acting Instructor (postdoc) Department of Applied Mathematics http://faculty.washington.edu/arahman2 -------------- next part -------------- An HTML attachment was scrubbed... URL: