Institution
National Technical University of Athens
Education•Athens, Attiki, Greece•
About: National Technical University of Athens is a education organization based out in Athens, Attiki, Greece. It is known for research contribution in the topics: Large Hadron Collider & Nonlinear system. The organization has 13445 authors who have published 31259 publications receiving 723504 citations. The organization is also known as: Athens Polytechnic & NTUA.
Topics: Large Hadron Collider, Nonlinear system, Context (language use), Finite element method, Computer science
Papers published on a yearly basis
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TL;DR: In this article, a two-phase model was proposed for water absorption in epoxide materials, based on the Guggenheim-Anderson-de Boer (GAB) equation, with the assumption that water diffusion can take place independently in different phases of the material in accordance with Fick's second law.
Abstract: The kinetics of water absorption in epoxide materials was studied by the aid of a diglycidyl ether of bisphenol-A–triethylenetetramine (DGEBA–TETA) epoxy–resin system containing various amounts of the plasticizer THIOCOL (0–40 phr). The presence of plasticizer permits the formation of products with different crosslinking densities and hydrophilic characters. Dynamic water absorption experiments were carried out at 15, 40, and 70°C. For the fitting of the experimental results, a new model was used, based on a model proposed earlier by Jacobs and Jones. This model considers epoxide product as a two-phase system consisting of a master phase (where the major part of the water is absorbed), which is homogeneous and nonpolar (phase 1), and of a second phase with different density and/or hydrophilic character (phase 2). By making the assumption that water diffusion can take place independently in the different phases of the material in accordance with Fick's second law, we can calculate the diffusion coefficient D and the water content at saturation M∞ for each phase separately. Equilibrium water sorption measurements were performed at 40°C, and the data were analyzed and discussed based on the Guggenheim–Anderson–de Boer (GAB) equation, the results being in support of the two-phase model used in the analysis of absorption kinetics. The linear expansion coefficient and the glass transition temperature of the materials, employed in the discussion of the results, were measured by thermomechanical analysis. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 1165–1182, 1999
202 citations
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University of California, Berkeley1, National Technical University of Athens2, University of California, Los Angeles3, University of Washington4, University of Cambridge5, College of William & Mary6, Cornell University7, Duke University8, University of Minnesota9, Carnegie Mellon University10, Oberlin College11, Massachusetts Institute of Technology12
TL;DR: The intelligent RAM or IRAM is proposed, which greatly increases the on-chip memory capacity by using DRAM technology instead of much less dense SRAM memory cells, and should allow cost-effective vector processors to reach performance levels much higher than those of traditional architectures.
Abstract: Members of the University of California, Berkeley, argue that the memory system will be the greatest inhibitor of performance gains in future architectures. Thus, they propose the intelligent RAM or IRAM. This approach greatly increases the on-chip memory capacity by using DRAM technology instead of much less dense SRAM memory cells. The resultant on-chip memory capacity coupled with the high bandwidths available on chip should allow cost-effective vector processors to reach performance levels much higher than those of traditional architectures. Although vector processors require explicit compilation, the authors claim that vector compilation technology is mature (having been used for decades in supercomputers), and furthermore, that future workloads will contain more heavily vectorizable components.
201 citations
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TL;DR: In this article, the authors deal with the determination of optimum tilt angle and orientation for solar photovoltaic arrays in order to maximize incident solar irradiance exposed on the array, for a specific period of time.
201 citations
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TL;DR: In this article, a new seismic design philosophy is illuminated, taking advantage of soil "failure" to protect the superstructure, instead of over-designing the foundation to ensure that the loading stemming from the structural inertia can be "safely" transmitted onto the soil, why not do exactly the opposite by intentionally under designing the foundation, to act as a safety valve?
Abstract: A new seismic design philosophy is illuminated, taking advantage of soil “failure” to protect the superstructure. Instead of over-designing the foundation to ensure that the loading stemming from the structural inertia can be “safely” transmitted onto the soil (as with conventional capacity design), and then reinforce the superstructure to avoid collapse, why not do exactly the opposite by intentionally under-designing the foundation to act as a “safety valve” ? The need for this “reversal” stems from the uncertainty in predicting the actual earthquake motion, and the necessity of developing new more rational and economically efficient earthquake protection solutions. A simple but realistic bridge structure is used as an example to illustrate the effectiveness of the new approach. Two alternatives are compared : one complying with conventional capacity design, with over-designed foundation so that plastic “hinging” develops in the superstructure; the other following the new design philosophy, with under-designed foundation, “inviting” the plastic “hinge” into the soil. Static “pushover” analyses reveal that the ductility capacity of the new design concept is an order of magnitude larger than of the conventional design: the advantage of “utilising” progressive soil failure. The seismic performance of the two alternatives is investigated through nonlinear dynamic time history analyses, using an ensemble of 29 real accelerograms. It is shown that the performance of both alternatives is totally acceptable for moderate intensity earthquakes, not exceeding the design limits. For large intensity earthquakes, exceeding the design limits, the performance of the new design scheme is proven advantageous, not only avoiding collapse but hardly suffering any inelastic structural deformation. It may however experience increased residual settlement and rotation: a price to pay that must be properly assessed in design.
201 citations
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Utrecht University1, Netherlands Environmental Assessment Agency2, Potsdam Institute for Climate Impact Research3, Wageningen University and Research Centre4, International Institute for Applied Systems Analysis5, Technical University of Berlin6, European Institute7, Kyoto University8, National Technical University of Athens9, Federal University of Rio de Janeiro10, Imperial College London11, Tsinghua University12, Joint Global Change Research Institute13, National Development and Reform Commission14, The Energy and Resources Institute15, National Research University – Higher School of Economics16, National Institute for Environmental Studies17, Indian Institute of Management Ahmedabad18
TL;DR: It is shown that implementation of current policies leaves a median emission gap of 22.4 to 28.2 GtCO 2 eq by 2030 with the optimal pathways to implement the well below 2 °C and 1.5C Paris goals, which shows that all countries would need to accelerate the implementation of policies for renewable technologies, while efficiency improvements are especially important in emerging countries and fossil-fuel-dependent countries.
Abstract: Many countries have implemented national climate policies to accomplish pledged Nationally Determined Contributions and to contribute to the temperature objectives of the Paris Agreement on climate change. In 2023, the global stocktake will assess the combined effort of countries. Here, based on a public policy database and a multi-model scenario analysis, we show that implementation of current policies leaves a median emission gap of 22.4 to 28.2 GtCO2eq by 2030 with the optimal pathways to implement the well below 2 °C and 1.5 °C Paris goals. If Nationally Determined Contributions would be fully implemented, this gap would be reduced by a third. Interestingly, the countries evaluated were found to not achieve their pledged contributions with implemented policies (implementation gap), or to have an ambition gap with optimal pathways towards well below 2 °C. This shows that all countries would need to accelerate the implementation of policies for renewable technologies, while efficiency improvements are especially important in emerging countries and fossil-fuel-dependent countries.
201 citations
Authors
Showing all 13584 results
Name | H-index | Papers | Citations |
---|---|---|---|
J. S. Lange | 160 | 2083 | 145919 |
Nicholas A. Peppas | 141 | 825 | 90533 |
Claude Amsler | 138 | 1454 | 135063 |
Y. B. Hsiung | 138 | 1258 | 94278 |
M. I. Martínez | 134 | 1251 | 79885 |
Elliott Cheu | 133 | 1219 | 91305 |
Evangelos Gazis | 131 | 1147 | 84159 |
Stavros Maltezos | 129 | 943 | 79654 |
Serkant Ali Cetin | 129 | 1369 | 85175 |
Matteo Cavalli-Sforza | 129 | 1273 | 89442 |
Stefano Colafranceschi | 129 | 1103 | 79174 |
Konstantinos Nikolopoulos | 128 | 931 | 75907 |
Ilya Korolkov | 128 | 884 | 75312 |
Martine Bosman | 128 | 942 | 73848 |
Sotirios Vlachos | 128 | 789 | 77317 |