22,836 research outputs found
LWR core thermal-hydraulic analysis : assessment and comparison of the range of applicability of the codes COBRA IIIC/MIT and COBRA IV-I
No full textBased on the M.S. thesis of the first author in the M.I.T. Dept. of Nuclear Engineering, 1978.This report summarizes the result of studies concerning the range of
applicability of two subchannel codes for a variety of thermal-hydraulic
analyses. The subchannel codes used include COBRA IIIC/MIT and the
newly developed code, COBRA IV-I which is considered the benchmark
code for the purpose of this report. Hence, through the comparisons
of the two codes, the applicability of COBRA IIIC/MIT is assessed
with respect to COBRA IV-I.
A variety of LWR thermal-hydraulic analyses are examined. Results
of both codes for steady-state and transient analyses are compared.
The types of analysis include BWR bundle-wide analysis, a simulated rod
ejection and loss of flow transients for a PWR. The system parameters
were changed drastically to reach extreme coolant conditions, thereby
establishing upper limits.
In addition to these cases, both codes are compared to experimental
data including measured coolant exit temperatures in a core, interbundle
mixing for inlet flow upset cases and two-subchannel flow blockage
measurements.
The comparisons showed that, overall, COBRA IIIC/MIT predicts most
thermal-hydraulic parameters quite satisfactorily. However, the clad
temperature predictions differ from those calculated by COBRA IV-I and
appear to be in error. These incorrect predictions are caused by the
discontinuity in the heat transfer coefficient at the start of boiling.
Hence, if the heat transfer package is corrected, then COBRA IIIC/MIT
should be just as applicable as the implicit option of COBRA IV-I.Final report for research project sponsored by Long Island Lighting Company and others under the MIT Energy Laboratory Electric Utility Program
CyberIR@MIT: Knowledge for Science, Policy, Practice
No full textThis paper presents a brief introduction to CyberIR@MIT—a dynamic, interactive knowledge and networking system focused on the evolving, diverse, and complex interconnections of cyberspace and international relations. The goal is to highlight key theoretical, substantive, empirical and networking issues.
CyberIR@MIT is anchored in a multidimensional ontology. It was initially framed as an experiment during the MIT-Harvard collaboration on Explorations in Cyber International Relations (see ecir.mit.edu) to serve as a forum for quality-controlled content and materials generated throughout the research project.
The method consists of differentiating among the various facets of human activity in (i) cyberspace, (ii) international relations, and (iii) the intersection of the cyber and “real.” It includes problems created by humans and solution strategies, as well as enabling functions and capabilities, on the one hand, and impediments to behavior and associated barriers, on the other. See https://cyberir.mit.edu for functions. The value of this initiative lies in its conceptual foundations and method of knowledge representation—embedded in an interactive system for knowledge submission, with search and retrieval functions.This material is based on work supported by the MIT Political Science Department & U.S. Department of Defense. Any opinions, findings, conclusions or recommendations therein are those of the author(s) and do not necessarily reflect the views of the U.S. Department of Defense
Engineering neuromuscular tissues for bidirectional neuroprosthetic interfacing
No full textThis electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Thesis: Ph. D. in Medical Engineering and Medical Physics, Harvard-MIT Program in Health Sciences and Technology, 2020Cataloged from student-submitted PDF of thesis.Includes bibliographical references (pages 208-242).Contemporary technological approaches to address limb loss and neuromuscular dysfunction consist of synthetic, mechanical devices which lack an intimate bidirectional interface with nervous tissues. On the therapeutic front, the current amputation paradigm disrupts neuromuscular architecture, discards sensory organs and provides no anatomical or prosthetic replacement. This precludes the generation of afferent sensory feedback, which is critical for sensory integration, motor planning, peripheral and central neurological health, and myoelectric prosthesis control. Utilizing a paradigm of coevolution, I simultaneously engineer neuromuscular anatomy and bioelectronics to enable seamless, bidirectional neuroprosthetic interfacing. In this dissertation, I describe the design and preclinical validation of the regenerative agonist-antagonist myoneural interface (AMI) and myodermal interface (MI), which are reconstructive surgical models to restore musculotendinous and cutaneous sensory feedback, respectively. Then, through case-control studies, the functional outcomes of human subjects who have undergone below-knee and above-knee amputations incorporating native AMIs are compared to standard amputation controls. The effect of AMI amputation on sensorimotor neuroplasticity is investigated through anatomical and functional neuroimaging. These preclinical and clinical evaluations demonstrate the a) production of graded efferent and afferent signals, b) the maintenance of peripheral limb volume and central sensorimotor substrates, c) improvements in phantom sensation, phantom pain, and neuroprosthetic controllability, and d) decreased dependence on compensatory visuomotor circuitry. To address challenges with functional electrical stimulation (FES) of neuromusculature, employed for prosthetic feedback and control, I develop a closed-loop functional optogenetic stimulation system (FOS) for peripheral neuromuscular control. This system demonstrates greater accuracy, biomimetic orderly recruitment of fibers, and minimized fatigue during cyclic movements as compared to FES. Spanning from animal models to human implementation, this dissertation presents 1) a model to design new surgical techniques for afferent/efferent signaling, 2) characterize the physiology following clinical translation, and 3) recursively apply the lessons to the design of neural interfaces back at the bench. In summary, the results of this work steer a shift of the clinical amputation paradigm towards one that performs strategic rewiring of neuromuscular constructs to enable improved neurological health and neural interfacing.Shriya Srinivasan.Ph. D. in Medical Engineering and Medical PhysicsPh. D. in Medical Engineering and Medical Physics Harvard-MIT Program in Health Sciences and Technolog
A Computational Theory of Animation
No full textThe author of this work is supported by an IBM Fellowship. The research described herein is being conducted at the Artificial Intelligence Laboratory, a Massachusetts Institute of Technology research program.A system is proposed capable of generating narrative computer animation in response to a simple script. The major problem addressed is how to imbed into the system some of the knowledge that animators use when creating animation. Infinitely many animated films can fulfill a single script. The system is faced with the problem of how to make a good one by making decisions in very under-constrained situations. This paper is a total revision of AI Working Paper 119.MIT Artificial Intelligence Laboratory
International Business Machines Corporatio
High grade uranium resources in the United States : an overview
No full textA time analysis of uranium exploration, production and known reserves in the United States is employed to reveal industry trends. The
basis for this analysis is the data collected, processed and published
by the A.E.C.'s Grand Junction Office. This analysis reveals that
exploration, thus the quantity of known uranium, has been governed
by demand. Factors affecting the prospects for future discoveries
are discussed. The author concludes that the resource base
may be substantially greater than is presently known, and calls for a
national research effort to better quantify the extent of our uranium
resources.National Science Foundation Grant #GI-3915
A Single-element method for heterogeneous nuclear reactors
No full textStatement of responsibility on title-page reads, S.S. Seth, M.J. Driscoll, I. Kaplan, T.J. Thompson and D.D. Lanning"May 1970.""MIT-3944-3."Also issued by the first author and supervised by the second and third author as a Sc. D. thesis in the Dept. of Nuclear Engineering, MIT, 1970Includes bibliographical references (leaves 169-176)U.S. Atomic Energy Commission contract AT(30-1) 394
Getting Started Computing at the AI Lab
No full textThis document describes the computing facilities at M.I.T. Artificial Intelligence Laboratory, and explains how to get started using them. It is intended as an orientation document for newcomers to the lab, and will be updated by the author from time to time.MIT Artificial Intelligence Laborator
A generalized study of the breeding potential of large heavy water moderated power reactors fueled with thoria and urania
No full text"January 1967.""MIT-2073-5."Also issued as a Ph. D. thesis by the first author and supervised by the second and third authors, Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1966Includes bibliographical references (pages 324-328)U.S. Atomic Energy Commission contract AT(30-1)-207
Friction factor and heat transfer correlation for irradiated organic coolants
No full text"September 1965."Series statement handwritten on cover"MIT-334-23 Chemistry."Also written as an M.S. theses written by the first author and advised by the second author, Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1966Includes bibliographical references (pages 163-165)M.I.T. DSR Project no. 9819Work performed for the Savannah River Operations Office, U.S. Atomic Energy Commission under contract no. AT(38-1)-33
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