• 제목/요약/키워드: Massachusetts Institute of Technology

검색결과 184건 처리시간 0.026초

Structure Formation in Multilayered Films Prepared by the Layer-by-Layer Deposition using PAA and HM-PEO

  • Seo, Jin-Hwa;Lutkenhaus Jodie L..;Kim, Jun-Oh;Hammond Paula T.;Char Kook-Heon
    • 한국고분자학회:학술대회논문집
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    • 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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    • pp.295-295
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    • 2006
  • In present study, poly(acrylic acid) (PAA) and hydrophobically modified poly(ethylene oxide) (HM-PEO) multilayers based on the hydrogen bonding between the component polymer pair have been prepared by the LbL deposition method. Dip assembled HM-PEO/PAA multilayers yield unique film morphologies in comparison with PEO/PAA multilayers due to the micellar formation of HM-PEO owing to the hydrophobic attraction between alkyl chains end-capped with the PEO chains. Individual HM-PEO micelles were connected through the bridging PEO chains to form temporary networks on multilayer surface and induced peculiar surface morphology on HM-PEO/PAA multilayers above the critical number of bilayers.

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Advances on the Behavior Characterization of FRP-Anchored Carbon Fiber-Reinforced Polymer (CFRP) Sheets Used to Strengthen Concrete Elements

  • Brena, Sergio F.;McGuirk, Geoffrey N.
    • International Journal of Concrete Structures and Materials
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    • 제7권1호
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    • pp.3-16
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    • 2013
  • Strengthening concrete structures using FRP composites is a commonly considered technology in many practical situations. The success of the strengthening intervention largely depends on adequate bond between FRP sheets and the concrete substrate. In recent years, techniques to anchor FRP sheets in applications where sheets must develop strength in a short length have been proposed. One of these techniques includes use of FRP anchors embedded into the concrete substrate and forming part of the composite strengthening system. This paper presents the results of studies conducted recently at the University of Massachusetts Amherst to advance the understanding on the behavior of FRP anchored systems.

Consequence-based security for microreactors

  • Emile Gateau;Neil Todreas;Jacopo Buongiorno
    • Nuclear Engineering and Technology
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    • 제56권3호
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    • pp.1108-1115
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    • 2024
  • Assuring physical security for Micro Modular Reactors (MMRs) will be key to their licensing. Economic constraints however require changes in how the security objectives are achieved for MMRs. A promising new approach is the so-called performance based (PB) approach wherein the regulator formally sets general security objectives and leaves it to the licensee to set their own specific acceptance criteria to meet those objectives. To implement the PB approach for MMRs, one performs a consequence-based analysis (CBA) whose objective is to study hypothetical malicious attacks on the facility, assuming that intruders take control of the facility and perform any technically possible action within a limited time before an offsite security force can respond. The scenario leading to the most severe radiological consequences is selected and studied to estimate the limiting impact on public health. The CBA estimates the total amount of radionuclides that would be released to the atmosphere in this hypothetical scenario to determine the total radiation dose to which the public would be exposed. The predicted radiation exposure dose is then compared to the regulatory dose limit for the site. This paper describes application of the CBA to four different MMRs technologies.

Musculoskeletal Disorders in Northeast Lobstermen

  • Fulmer, Scott;Buchholz, Bryan;Scribani, Melissa;Jenkins, Paul
    • Safety and Health at Work
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    • 제8권3호
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    • pp.282-289
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    • 2017
  • Background: The objective of this study was to report on the prevalence of musculoskeletal pain in lobstermen in the northeast USA. Methods: Crews were randomly selected from those licensed to fish in Maine and Massachusetts and followed prospectively. The survey used a Nordic Musculoskeletal Questionnaire format to characterize musculoskeletal disorders. Results: A total of 395 individuals participated. One half of the respondents reported low back pain. Back pain was attributed to or exacerbated by lobstering. Low back pain was prevalent among both captains and sternmen, while sternmen reported more hand/wrist pain than captains. Multiple locations for pain were common in individual participants. Conclusion: Equipment or technology to assist material handling should be a priority, as the body segments with high prevalence of pain (back, hand/wrists, shoulders, knees) are all affected by the repetitive and forceful handling of the lobster traps.

Dynamic analysis and controller design for a slider-crank mechanism with piezoelectric actuators

  • Akbari, Samin;Fallahi, Fatemeh;Pirbodaghi, Tohid
    • Journal of Computational Design and Engineering
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    • 제3권4호
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    • pp.312-321
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    • 2016
  • Dynamic behaviour of a slider-crank mechanism associated with a smart flexible connecting rod is investigated. Effect of various mechanisms' parameters including crank length, flexibility of the connecting rod and the slider's mass on the dynamic behaviour is studied. Two control schemes are proposed for elastodynamic vibration suppression of the flexible connecting rod and also obtaining a constant angular velocity for the crank. The first scheme is based on feedback linearization approach and the second one is based on a sliding mode controller. The input signals are applied by an electric motor located at the crank ground joint, and two layers of piezoelectric film bonded to the top and bottom surfaces of the connecting rod. Both of the controllers successfully suppress the vibrations of the elastic linkage.

Magnetic Tunnel Junctions with Magnesium Oxide Barriers

  • Nagahama Taro;Moodera Jagadeesh S.
    • Journal of Magnetics
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    • 제11권4호
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    • pp.170-181
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    • 2006
  • Spin dependent tunneling has enormously activated the field of magnetism in general, and in particular spin transport studies, in the past ten years. Thousands of articles related to the subject have appeared with many fundamental results. Importantly, there is great interest in their potential for application. There was another surge of activity in this field since the past five years - created by the theoretical prediction of a large tunnel magnetoresistance that arises due to band symmetry matched coherent tunneling in epitaxial magnetic tunnel junctions with (001) MgO barrier and experimentally well demonstrated. This further development in the field has boosted the excitement in both fundamental science as well as the possibility of application in such as magnetic random access memory, ultra sensitive read heads, biosensors and spin torque diodes. This review is a brief coverage of the field highlighting the literature that deals with magnetic tunnel junctions having epitaxial MgO tunnel barriers.

박막에서의 박막두께에 따른 자기탄성계수의 거동 예측 (Magnetoelastic Coupling Coefficients with Film Thicknesses in Ultrathin Films)

  • 송오성
    • 한국자기학회지
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    • 제5권2호
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    • pp.112-114
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    • 1995
  • 매우 얇은 박막에서 자기탄성계수는 효과이방성에너지와 마찬가지로 박막두께에 반비례하여, B/sup eff/ = B/sup b/ + B/sup s/ /t 으로 수학적, 물리적으로 예측됨을 보였다. 이러한 박막두께가 얇아질수록 표면자기탄성계수(surface magnetoelastic coupling coefficient)에 의한 영향이 커지므로 많은 공학적 의미를 내포하고 있다.

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