[Video] PRISM Seminar Series
http://nanohub.org/resources/5699
Tue, 18 Jun 2019 02:56:48 +0000HUBzero - The open source platform for scientific and educational collaborationnanoHUB.orgsupport@nanohub.orgnodevices, nano electro-mechanical systems, reliability, rf memsJayathi Murthyen-gbCopyright 2019 nanoHUB.orgResourcesNear-field radiative heat transfer and Casimir Force Measurement
http://nanohub.org/resources/8052
This presentation first makes a simple introduction on how the charge fluctuations give rises to these effects that are nowadays most effectively detected using MEMS or AFM technologies. This will lead to question the relevance of these effects in the use of MEMS. After description of our quantitative measurement of the Casimir force and comparison with theory, I shall report on our experimental data on the thermal flux spatial dependence. Theory based on the Derjaguin approximation, successfully used here for the first time to describe radiative heat transfer from the far field to the near field regimes, reproduces the measured dependence.http://nanohub.org/site/resources/2009/12/08055/2009.10.23-Chevrier-PRISM.mp4This presentation first makes a simple introduction on how the charge fluctuations give rises to these effects that are nowadays most effectively detected using MEMS or AFM technologies. This will lead to question the relevance of these effects in the use of MEMS. After description of our quantitative measurement of the Casimir force and comparison with theory, I shall report on our experimental data on the thermal flux spatial dependence. Theory based on the Derjaguin approximation, successfully used here for the first time to describe radiative heat transfer from the far field to the near field regimes, reproduces the measured dependence.nohosted/taped by NCN@Purdue, from outside NCN, MEMS, AFM, Casimir forcesJoel ChevrierJoel ChevrierOnline PresentationsThu, 31 May 2012 02:26:04 +0000http://nanohub.org/site/resources/2009/12/08055/2009.10.23-Chevrier-PRISM.mp4Development of the ReaxFF reactive force fields and applications to combustion, catalysis and material failure
http://nanohub.org/resources/11774
This lecture will describe how the traditional, non-reactive FF-concept can be extended for application including reactive events by introducing bond order/bond distance concepts. Furthermore, it will address how these reactive force fields can be trained against QM-data, thus greatly enhancing their reliability and transferability.http://nanohub.org/site/resources/2011/07/11778/2011.06.10-Duin-PRISM-320x240.mp4This lecture will describe how the traditional, non-reactive FF-concept can be extended for application including reactive events by introducing bond order/bond distance concepts. Furthermore, it will address how these reactive force fields can be trained against QM-data, thus greatly enhancing their reliability and transferability.nomolecular dynamics, quantum mechanics, hosted/taped by NCN@Purdue, from outside NCN, 1st principles, materials scienceAdri van DuinAdri van DuinOnline PresentationsMon, 12 Sep 2011 20:24:51 +0000http://nanohub.org/site/resources/2011/07/11778/2011.06.10-Duin-PRISM-320x240.mp4Experiments and Models Regarding Strain Dependent Thermal Conductivity and Strength at the Nanoscale and Microscale
http://nanohub.org/resources/11603
Silicon micro- and nano-structures are essential in today’s integrated circuits and sensors. The functioning and performance of such devices are highly affected by thermal properties. Due to the size effect, the thermal properties of bulk silicon cannot represent those of silicon micro-structures. Furthermore, stress/strain inside the silicon structures can have a significant effect on their thermal properties. ...http://nanohub.org/site/resources/2011/07/11605/2011.04.29-Tomar-PRISM-320x240.mp4Silicon micro- and nano-structures are essential in today’s integrated circuits and sensors. The functioning and performance of such devices are highly affected by thermal properties. Due to the size effect, the thermal properties of bulk silicon cannot represent those of silicon micro-structures. Furthermore, stress/strain inside the silicon structures can have a significant effect on their thermal properties. ...nonanocomposites, hosted/taped by NCN@Purdue, experiments, from Purdue, material properties, strain, Si, materials science, thermal conductivity, supperlatticesVikas TomarVikas TomarOnline PresentationsThu, 22 Sep 2011 20:14:55 +0000http://nanohub.org/site/resources/2011/07/11605/2011.04.29-Tomar-PRISM-320x240.mp4From density functional theory to defect level in silicon: Does the “band gap problem” matter?
http://nanohub.org/resources/5495
Modeling the electrical effects of radiation damage in semiconductor devices requires a detailed description of the properties of point defects generated during and subsequent to irradiation. Such modeling requires physical parameters, such as defect electronic levels, to describe carrier recombination. Density functional theory (DFT) is the method of choice for first-principles simulations of defects. However, DFT typically hugely underestimates the fundamental band gap in semiconductors, and the band gap is the energy scale of interest for defect levels. Moreover, boundary conditions in the supercell approximation used in DFT calculations of defects also can inject large errors and uncertainties. I describe a new, more rigorous methodology for supercell calculations, implemented in the SeqQuest DFT code, that incorporates a proper treatment of electrostatic boundary conditions, locates a fixed chemical potential for the net defect electron charge, includes the bulk dielectric response, and creates a robust computational model of isolated defects. Using this methodology, the computed DFT defect level spectrum for a wide variety of Si defects spans the experimental Si gap, i.e., exhibits no band gap problem, and the DFT results agree remarkably well with experiment for those values that are experimentally known. The new scheme adds rigor to computing defect properties, and has important implications for density functional theory development.http://nanohub.org/site/resources/2008/09/05498/2008.08.21-schultz-nt501.mp4Modeling the electrical effects of radiation damage in semiconductor devices requires a detailed description of the properties of point defects generated during and subsequent to irradiation. Such modeling requires physical parameters, such as defect electronic levels, to describe carrier recombination. Density functional theory (DFT) is the method of choice for first-principles simulations of defects. However, DFT typically hugely underestimates the fundamental band gap in semiconductors, and the band gap is the energy scale of interest for defect levels. Moreover, boundary conditions in the supercell approximation used in DFT calculations of defects also can inject large errors and uncertainties. I describe a new, more rigorous methodology for supercell calculations, implemented in the SeqQuest DFT code, that incorporates a proper treatment of electrostatic boundary conditions, locates a fixed chemical potential for the net defect electron charge, includes the bulk dielectric response, and creates a robust computational model of isolated defects. Using this methodology, the computed DFT defect level spectrum for a wide variety of Si defects spans the experimental Si gap, i.e., exhibits no band gap problem, and the DFT results agree remarkably well with experiment for those values that are experimentally known. The new scheme adds rigor to computing defect properties, and has important implications for density functional theory development.nodevices, nanoelectronics, research seminar, reliability, hosted/taped by NCN@Purdue, from outside NCN, radiation effects, device simulations, radiation damage, density functional theoryPeter A. SchultzPeter A. SchultzOnline PresentationsWed, 01 Oct 2008 20:05:56 +0000http://nanohub.org/site/resources/2008/09/05498/2008.08.21-schultz-nt501.mp4Emerging Opportunities, Challenges, and Applications in Exascale Computing
http://nanohub.org/resources/10981
The move towards exascale computing platforms (capable of 10^18 floating point operations) poses tremendous challenges, while presenting opportunities for foundational advances in a variety of application domains. In this talk, I will describe various technical issues that must be overcome to realize the potential of exascale computing platformshttp://nanohub.org/site/resources/2011/03/10988/2011.02.18-Grama-PRISM-320x240.mp4The move towards exascale computing platforms (capable of 10^18 floating point operations) poses tremendous challenges, while presenting opportunities for foundational advances in a variety of application domains. In this talk, I will describe various technical issues that must be overcome to realize the potential of exascale computing platformsnoresearch seminar, hosted/taped by NCN@Purdue, from Purdue, high performance computing, Parallel and distributerd computing, AMD, Intel, Parallel ProcessingAnanth GramaAnanth GramaOnline PresentationsThu, 10 Mar 2011 22:11:23 +0000http://nanohub.org/site/resources/2011/03/10988/2011.02.18-Grama-PRISM-320x240.mp4The Challenges of Micro-System Product Development
http://nanohub.org/resources/6848
This talk will discuss the historical development of micro‐system technology, the products that have been developed and the challenges to development of a reliable product.http://nanohub.org/site/resources/2009/06/06851/2008.09.19-Allen-PRISM.mp4This talk will discuss the historical development of micro‐system technology, the products that have been developed and the challenges to development of a reliable product.nonano electro-mechanical systems, research seminar, reliability, hosted/taped by NCN@Purdue, from outside NCN, innovationJames J. AllenJames J. AllenOnline PresentationsFri, 05 Jun 2009 14:35:20 +0000http://nanohub.org/site/resources/2009/06/06851/2008.09.19-Allen-PRISM.mp4Experiences with nonintrusive polynomial Chaos and stochastic collocation methods for uncertainty analysis and design
http://nanohub.org/resources/5910
Non—intrusive polynomial chaos expansion (PCE) and stochastic collocation (SC) methods are attractive techniques for uncertainty quantification due to their abilities to produce functional representations of stochastic variability and to achieve exponential convergence rates in statistics of interest. Whereas PCE estimates coefficients for known orthogonal polynomial basis functions, SC forms Lagrange interpolants for known coefficients. The latest results in comparing PCE and SC and embedding these methods within design under uncertainty will be presented.http://nanohub.org/site/resources/2008/11/05913/2008.10.31-eldred-prism.mp4Non—intrusive polynomial chaos expansion (PCE) and stochastic collocation (SC) methods are attractive techniques for uncertainty quantification due to their abilities to produce functional representations of stochastic variability and to achieve exponential convergence rates in statistics of interest. Whereas PCE estimates coefficients for known orthogonal polynomial basis functions, SC forms Lagrange interpolants for known coefficients. The latest results in comparing PCE and SC and embedding these methods within design under uncertainty will be presented.noalgorithms, nano electro-mechanical systems, reliability, hosted/taped by NCN@Purdue, from outside NCNMichael S. EldredMichael S. EldredOnline PresentationsFri, 13 Mar 2009 20:37:12 +0000http://nanohub.org/site/resources/2008/11/05913/2008.10.31-eldred-prism.mp4Molecular Sensors for MEMS
http://nanohub.org/resources/7998
This seminar will cover the issues involved in using molecular sensors in MEMS and their application to microchannels, supersonic micronozzles, microjet impingement, microturbines and unsteady fluidic actuators.http://nanohub.org/site/resources/2009/12/08001/2009.11.20-Sullivan-PRISM.mp4This seminar will cover the issues involved in using molecular sensors in MEMS and their application to microchannels, supersonic micronozzles, microjet impingement, microturbines and unsteady fluidic actuators.nodevices, nano electro-mechanical systems, thermal transport, research seminar, nanofluidics, sensors, thermodynamics, hosted/taped by NCN@Purdue, from PurdueJohn P. SullivanJohn P. SullivanOnline PresentationsThu, 10 Dec 2009 16:22:56 +0000http://nanohub.org/site/resources/2009/12/08001/2009.11.20-Sullivan-PRISM.mp4Gas Damping of Microcantilevers at Low Ambient Pressures
http://nanohub.org/resources/5683
This seminar will present a theoretical model for predicting the gas damping of long, rectangular silicon microcantilevers, which are oscillating in an unbounded gaseous medium with the ambient pressures varying over 5 orders of magnitude (1000 > Kn > 0.03). The work is the result of a collaboration with Prof. Alina Alexeenko (AAE). The surrounding gas flow is modeled using a sub—continuum, quasisteady Boltzmann equation with a simplified ellipsoidal statistical Bhatnagar—Gross—Krook (ES—BGK) collision operator. The computational results of the model are used to present a closed—form correlation for gas damping of different microcantilever vibration modes. The correlation is uniformly valid over 5 orders of magnitude of Kn numbers easily spanning the range over the free—molecular, the transition, and the low—pressure slip flow regimes. This presentation, will also compare the predictions of this theoretical model with the detailed experimental data acquired by Ryan Tung through controlled pressure vacuum chamber experiments with silicon microcantilevers vibrating in the fundamental and higher vibration modes. The experiments were recently performed by Ryan Tung in collaboration with Dr. H. Sumali at the Sandia National Laboratories, New Mexico. The agreement between theory and experiments is excellent.http://nanohub.org/site/resources/2008/10/05686/2008.10.17-bidkar-prism.mp4This seminar will present a theoretical model for predicting the gas damping of long, rectangular silicon microcantilevers, which are oscillating in an unbounded gaseous medium with the ambient pressures varying over 5 orders of magnitude (1000 > Kn > 0.03). The work is the result of a collaboration with Prof. Alina Alexeenko (AAE). The surrounding gas flow is modeled using a sub—continuum, quasisteady Boltzmann equation with a simplified ellipsoidal statistical Bhatnagar—Gross—Krook (ES—BGK) collision operator. The computational results of the model are used to present a closed—form correlation for gas damping of different microcantilever vibration modes. The correlation is uniformly valid over 5 orders of magnitude of Kn numbers easily spanning the range over the free—molecular, the transition, and the low—pressure slip flow regimes. This presentation, will also compare the predictions of this theoretical model with the detailed experimental data acquired by Ryan Tung through controlled pressure vacuum chamber experiments with silicon microcantilevers vibrating in the fundamental and higher vibration modes. The experiments were recently performed by Ryan Tung in collaboration with Dr. H. Sumali at the Sandia National Laboratories, New Mexico. The agreement between theory and experiments is excellent.nonano electro-mechanical systems, research seminar, atomic force microscopy, nanocantilevers, hosted/taped by NCN@Purdue, experiments, from PurdueRahul Anil BidkarRahul Anil BidkarOnline PresentationsMon, 03 Nov 2008 19:46:36 +0000http://nanohub.org/site/resources/2008/10/05686/2008.10.17-bidkar-prism.mp4Peanuts vs. Pyramids: Two Perspectives on MEMS
http://nanohub.org/resources/7868
MEMS, the acronym for Micro-electromechanical Systems, also known simply as “Micro-systems,” come in two main types: commodity products (the peanuts) and MEMS-enabled products (the pyramids, or, more correctly, the inverted pyramids). The economics of scale greatly affect how these two classes of products are designed, built, manufactured, and sold. The contrast is illustrated with two real-world examples: The Knowles SiSonic&tm; silicon cell-phone microphone, and the Polychromix PhazIR&tm;, a fully portable battery-operated hand-held near-infrared spectrometer.http://nanohub.org/site/resources/2009/11/07871/2009.11.12-Senturia-NT501.mp4MEMS, the acronym for Micro-electromechanical Systems, also known simply as “Micro-systems,” come in two main types: commodity products (the peanuts) and MEMS-enabled products (the pyramids, or, more correctly, the inverted pyramids). The economics of scale greatly affect how these two classes of products are designed, built, manufactured, and sold. The contrast is illustrated with two real-world examples: The Knowles SiSonic&tm; silicon cell-phone microphone, and the Polychromix PhazIR&tm;, a fully portable battery-operated hand-held near-infrared spectrometer.nonano electro-mechanical systems, research seminar, sensors, hosted/taped by NCN@Purdue, from outside NCN, optics, Spectroscopy, from MITStephen D. SenturiaStephen D. SenturiaOnline PresentationsTue, 29 Dec 2009 21:26:24 +0000http://nanohub.org/site/resources/2009/11/07871/2009.11.12-Senturia-NT501.mp4Nanotribology, Nanomechanics and Materials Characterization Studies
http://nanohub.org/resources/6573
Fundamental nanotribological studies provide insight to molecular origins of interfacial phenomena including adhesion, friction, wear and lubrication. Friction and wear of lightly loaded micro/nano components are highly dependent on the surface interactions (few atomic layers). Nanotribological and nanomechanics studies are also valuable in the fundamental understanding of interfacial phenomena in macrostructures to provide a bridge between science and engineering. This talk will present an overview of nanotribological and nanomechanics studies and their applications.http://nanohub.org/site/resources/2009/03/06576/2009.03.06-Bhushan-PRISM.mp4Fundamental nanotribological studies provide insight to molecular origins of interfacial phenomena including adhesion, friction, wear and lubrication. Friction and wear of lightly loaded micro/nano components are highly dependent on the surface interactions (few atomic layers). Nanotribological and nanomechanics studies are also valuable in the fundamental understanding of interfacial phenomena in macrostructures to provide a bridge between science and engineering. This talk will present an overview of nanotribological and nanomechanics studies and their applications.nocarbon nanotubes, nano electro-mechanical systems, research seminar, atomic force microscopy, scanning tunneling microscopy, surfaces, nanotribology, processing, nano/bio, polymers, hosted/taped by NCN@Purdue, materials, from outside NCN,...Bharat BhushanBharat BhushanOnline PresentationsMon, 08 Jun 2009 16:14:05 +0000http://nanohub.org/site/resources/2009/03/06576/2009.03.06-Bhushan-PRISM.mp4