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Resonance Raman Spectroscopy to Study and Characterize Defects on Carbon Nanotubes and other Nano-Graphite Systems

MRS Online Proceedings Library (OPL) 2011年第1期858卷 HH11.2-HH11.2页

作者： Ado Jorio Luiz Gustavo Cançado Bernardo R. A. Neves Mauricio de Souza Cristiano Fantini Marcos A. Pimenta G. Medeiros-Ribeiro Georgii G. Samsonidze Shin Grace Chou Gene Dresselhaus Depto. de Física Universidade Federal de Minas Gerais Belo Horizonte Minas Gerais Brazil. Laboratório Nacional de Luz Síncrotron Campinas São Paulo Brazil. Dept. of Electrical Engineering and Computer Science MIT Cambridge MA USA. Dept. of Chemistry MIT Cambridge MA USA. Francis Bitter Magnet Laboratory MIT Cambridge MA USA.

The use of resonance Raman spectroscopy (RRS) to study and characterize single wall carbon nanotubes (SWNTs) is discussed, focusing on preliminary efforts for the development of the RRS to characterize defects in SWNTs. The disorder-induced D-band, disorder-induced peaks just above the first-order allowed graphite G-band, as well as the intermediate frequency modes (IFMs) appearing between the RBM and the D/G spectral region are addressed. RRS on nanographite ribbons and on a step-like defect in highly ordered pyrolytic graphite (HOPG) sheds light into the problem of characterizing specific defects in nano-related carbons.

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Experimental Characterization of the Reliability of 3-Terminal Dual-Damascene Copper Interconnect Trees

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MRS Online Proceedings Library 2011年第1期716卷 8131-8136页

作者： Gan, C. L. Thompson, C. V. Pey, K. L. Choi, W. K. Wei, F. Yu, B. Hau-Riege, S. P. Advanced Materials for Micro- and Nano- Systems Programme Singapore-MIT Alliance Singapore Department of Materials Science and Engineering Massachusetts Institute of Technology Cambridge USA National University of Singapore now with School of Electrical & Electronics Engineering Nanyang Technological University Nanyang Avenue Singapore Department of Electrical & Computer Engineering National University of Singapore Singapore Institute of Microelectronics San Jose USA Intel Corp. Hillsborough OR 97124 now with Lawrence Livermore National Laboratory Livermore USA

Electromigration experiments have been carried out on simple Cu dual-damascene interconnect tree structures consisting of straight via-to-via (or contact-to-contact) lines with an extra via in the middle of the line. As with Al-based interconnects, the reliability of a segment in this tree strongly depends on the stress conditions of the connected segment. Beyond this, there are important differences in the results obtained under similar test conditions for Al-based and Cu-based interconnect trees. These differences are thought to be associated with variations in the architectural schemes of the two metallizations. The absence of a conducting electromigrationresistant overlayer in Cu technology, and the possibility of liner rupture at stressed vias lead to significant differences in tree reliabilities in Cu compared to Al.

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Teaching oral communication at mit: The concept module

Teaching oral communication at MIT: The concept module

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2010 2nd International Conference on Education Technology and computer, ICETC 2010

作者： Eng, Tony L. Department of Electrical Engineering and Computer Science MIT Cambridge United States

ISBN: (纸本)9781424463688

In this paper, we introduce a teaching module used in an oral communications course at mit to teach students how to (1) present technical material to a non-technical audience and (2) recover from things that may go wrong during a presentation. This module consists of various classroom activities that are all centered around an assignment in which students prepare a talk in order to explain a technical topic of their choosing to a non-technical audience. The entire experience culminates in a one-day conference attended by local high school students who serve as a live non-technical target audience for these talks. Here, we describe and discuss the various components of the module, with the hope that fellow practitioners will adopt and adapt the module for use in their home institution, and suggest modifications and improvements. © 2010 IEEE.

关键词： Students

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Carrier-envelope phase stabilization of a soliton-effect compressed sub-two-cycle pulse source

Carrier-envelope phase stabilization of a soliton-effect com...

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Conference on Lasers and Electro-Optics Europe (CLEO EUROPE)

作者： A. A. Amorim L. M. Bernardo F. X. Kärtner H. M. Crespo IFIMUP and IN-Institute of Nanoscience and Nanotechnology Departamento de Física Faculdade de Ciências Universidade do Porto Porto Portugal Departamento de Física ISEP Porto Portugal Department of Electrical Engineering and Computer Science and Research Laboratory of Electronics MIT Cambridge MA USA

ISBN: (纸本)9781457705328

After the first measurements of the carrier-envelope phase (CEP) drift between successive pulses from a Ti:Sapphire oscillator were obtained by time-domain cross-correlation, several techniques for the detection and stabilization of the CEP of femtosecond laser pulses have been developed. These methods represent an essential tool for applications where CEP-stabilized pulses are required, such as attosecond science, frequency metrology, precision spectroscopy and extreme nonlinear optics.

关键词： Optimized production technology Oscillators Optical interferometry Signal to noise ratio Laser stability Measurement by laser beam Fiber lasers

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Optimal reverse carpooling over wireless networks - A distributed optimization approach

Optimal reverse carpooling over wireless networks - A distri...

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44th Annual Conference on Information sciences and Systems, CISS 2010

作者： ParandehGheibi, Ali Ozdaglar, Asuman Effros, Michelle Médard, Muriel Department of Electrical Engineering and Computer Science MIT United States Department of Electrical Engineering California Institute of Technology United States

ISBN: (纸本)9781424474172

We focus on a particular form of network coding, reverse carpooling, in a wireless network where the potentially coded transmitted messages are to be decoded immediately upon reception. The network is fixed and known, and the system performance is measured in terms of the number of wireless broadcasts required to meet multiple unicast demands. Motivated by the structure of the coding scheme, we formulate the problem as a linear program by introducing a flow variable for each triple of connected nodes. This allows us to have a formulation polynomial in the number of nodes. Using dual decomposition and projected subgradient method, we present a decentralized algorithm to obtain optimal routing schemes in presence of coding opportunities. We show that the primal sub-problem can be expressed as a shortest path problem on an edge-graph, and the proposed algorithm requires each node to exchange information only with its neighbors. ©2010 IEEE.

关键词： Network coding

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Bounds on tracking error using closed-loop rapidly-exploring random trees

Bounds on tracking error using closed-loop rapidly-exploring...

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作者： Luders, Brandon D. Karaman, Sertac Frazzoli, Emilio How, Jonathan P. Dept. of Aeronautics and Astronautics MIT United States Dept. of Electrical Engineering and Computer Science MIT United States

ISBN: (纸本)9781424474264

This paper considers the real-time motion planning problem for autonomous systems subject to complex dynamics, constraints, and uncertainty. Rapidly-exploring random trees (RRT) can be used to efficiently construct trees of dynamically feasible trajectories;however, to ensure feasibility, it is critical that the system actually track its predicted trajectory. This paper shows that under certain assumptions, the recently proposed closed-loop RRT (CL-RRT) algorithm can be used to accurately track a trajectory with known error bounds and robust feasibility guarantees, without the need for replanning. Unlike open-loop approaches, bounds can be designed on the maximum prediction error for a known uncertainty distribution. Using the property that a stabilized linear system subject to bounded process noise has BIBO-stable error dynamics, this paper shows how to modify the problem constraints to ensure long-term feasibility under uncertainty. Simulation results are provided to demonstrate the effectiveness of the closed-loop RRT approach compared to open-loop alternatives. © 2010 AACC.

关键词： Trajectories

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Computational models of narrative: Review of the workshop

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AI Magazine 2010年第2期31卷 97-100页

作者： Finlayson, Mark A. Richards, Whitman Winston, Patrick H. Electrical Engineering and Computer Science Massachusetts Institute of Technology United States Department of Brain and Cognitive Sciences Massachusetts Institute of Technology United States Department of Cognitive Science Media Arts and Sciences MIT Media Lab United States Department of Artificial Intelligence and Computer Science MIT United States MIT Artificial Intelligence Laboratory United States

On October 8-10,2009, an interdisciplinary group met in Beverley, Massachusetts, to evaluate the state of the art in the computational modeling of narrative. Three important findings emerged: (1) current work in computational modeling is described by three different levels of representation;(2) there is a paucity of studies at the highest, most abstract level aimed at inferring the meaning or message of the narrative;and (3) there is a need to establish a standard data bank of annotated narratives, analogous to the Penn Treebank. Copyright © 2010, Association for the Advancement of Artificial Intelligence. All rights reserved.

关键词： Computation theory

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Non-invasive brain signal interface for a wheelchair navigation

Non-invasive brain signal interface for a wheelchair navigat...

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作者： Shin, Bong-Gun Kim, Taesoo Jo, Sungho Department of Computer Science KAIST Daejeon Korea Republic of Department of Electrical Engineering and Computer Science MIT MA United States

ISBN: (纸本)9781424474530

This work presents that, only using non-invasively captured brain signals, a person can navigate an electric wheelchair with no serious training for a long term. Only two electrodes are set on the scalp non-invasively to detect a P300 EEG signal and a reference signal. A simple signal processing interprets the measured signals to decide a movement direction of the wheelchair. The whole devices are loaded on the wheelchair. No external system is required. The experimental results demonstrate the feasibility of the simple BCI processing to achieve reasonable performance. ©ICROS.

关键词： Wheelchairs

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Band-Gap Modulation and Kohn Anomalies in Two-Dimensional Graphite and Single-Wall Carbon Nanotubes

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MRS Online Proceedings Library (OPL) 2011年第1期963卷 0963-Q01-06-0963-Q01-06页

作者： Georgii Samsonidze Eduardo B. Barros Hyungbin Son Riichiro Saito Gene Dresselhaus Mildred S. Dresselhaus gsm@mgm.mit.edu Massachusetts Institute of Technology Department of Electrical Engineering and Computer Science 77 Massachusetts Ave. Room 13-3021 Cambridge MA 02139 United States 617-253-6860 617-253-6827 ebarros@flex.phys.tohoku.ac.jp Universidade Federal do Ceara Fortaleza 60455-760 Brazil being@mit.edu Massachusetts Institute of Technology Cambridge MA 02139 United States rsaito@flex.phys.tohoku.ac.jp Tohoku University and CREST JST Sendai 980-8578 Japan gene@mgm.mit.edu Massachusetts Institute of Technology Cambridge MA 02139 United States millie@mgm.mit.edu Massachusetts Institute of Technology Cambridge MA 02139 United States

The electron-phonon coupling in two-dimensional graphite (graphene sheet) and metallic single-wall carbon nanotubes (SWNTs) is analyzed. In the graphene sheet the G-band phonon mode induces oscillations of the Fermi points, while the G′-band phonon mode opens a dynamical (oscillating with the phonon frequency) band gap, and accordingly, both phonon modes exhibit Kohn anomalies. Similarly, truly metallic armchair SWNTs undergo Peierls transitions driven by the G−- and G′-band phonon modes both of which open a dynamical band gap. In addition, the dynamical band gap induces a non-linear dependence of the phonon frequencies on the doping level and gives rise to strong anharmonic effects in the graphene sheet and metallic SWNTs.

关键词： nanostructure Raman spectroscopy thermal conductivity

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Measurement of the nonlinear elasticity of red blood cell membranes

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Physical Review E 2011年第5期83卷 051925-051925页

作者： YongKeun Park Catherine A. Best Tatiana Kuriabova Mark L. Henle Michael S. Feld Alex J. Levine Gabriel Popescu G. R. Harrison Spectroscopy Laboratory Massachusetts Institute of Technology Cambridge Massachusetts 02139 USA Harvard-MIT Division of Health Science and Technology Massachusetts Institute of Technology Cambridge Massachusetts 02139 USA College of Medicine University of Illinois at Urbana-Champaign Urbana Illinois 61801 USA Department of Physics University of Colorado Boulder Colorado 80309 USA School of Engineering and Applied Sciences Harvard University Cambridge Massachusetts 02138 USA Department of Chemistry & Biochemistry and Department of Physics & Astronomy UCLA Los Angeles California 90095 USA Quantitative Light Imaging Laboratory Department of Electrical and Computer Engineering Beckman Institute for Advanced Science & Technology University of Illinois at Urbana-Champaign Urbana Illinois 61801 USA

The membranes of human red blood cells (RBCs) are a composite of a fluid lipid bilayer and a triangular network of semiflexible filaments (spectrin). We perform cellular microrheology using the dynamic membrane fluctuations of the RBCs to extract the elastic moduli of this composite membrane. By applying known osmotic stresses, we measure the changes in the elastic constants under imposed strain and thereby determine the nonlinear elastic properties of the membrane. We find that the elastic nonlinearities of the shear modulus in tensed RBC membranes can be well understood in terms of a simple wormlike chain model. Our results show that the elasticity of the spectrin network can mostly account for the area compression modulus at physiological osmolality, suggesting that the lipid bilayer has significant excess area. As the cell swells, the elastic contribution from the now tensed lipid membrane becomes dominant.

关键词： ERYTHROCYTES CELL membranes ELASTICITY BIOLOGICAL membranes -- Fluidity LIPID membranes

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