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IEEE Innovative Smart Grid Technologies - Asia (ISGT Asia)

作者： A. M. Shiddiq Yunus A. Abu-Siada M. A. S. Masoum Department of Mechanical Engineering Energy Conversion Study Program State of Polytechnic Ujung Pandang Makassar Indonesia Department of Electrical and Computer Engineering Curtin University of Technology Perth WA Australia

The amount of wind turbine connected to the power grid has significantly increased during the last decade. This has resulted in essential need to establish grid codes. Previously, wind turbine generators (WTGs) were allowed to be disconnected from the network during any disturbance at the grid side to avoid WTGs from being damaged. However, lately, the transmission system operators (TSOs) require WTGs to be stayed connected to provide support to the grid during fault. This new requirement has been regulated in the new grid codes. In this paper, the super conducting magnetic energy storage (SMES) unit is used to enhance the high voltage ride through (HVRT) capability of DFIG based WTG during voltage swell events at the grid side. Two new grid codes are used to verify the ability of the SMES unit to avoid the WTG from being disconnected from the grid.

关键词： Coils Wind turbines Fuzzy logic Generators Reactive power Input variables Voltage fluctuations

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Improvement of LVRT capability of variable speed wind turbine generators using SMES unit

Improvement of LVRT capability of variable speed wind turbin...

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IEEE Innovative Smart Grid Technologies - Asia (ISGT Asia)

作者： A. M. Shiddiq Yunus A. Abu-Siada Mohammad A. S. Masoum Department of Mechanical Engineering Energy Conversion Study Program State of Polytechnic Ujung Pandang Makassar Indonesia Department of Electrical and Computer Engineering Curtin University of Technology Perth WA Australia

The ability of variable speed wind turbines technology to optimally tracking the power from wind energy has become the main reason of their popularity compared with the fixed speed wind turbines. In the earlier stage of connecting wind turbines (WTs) to the existing electricity grids, WTs were allowed to be disconnected from the grid in case of grid faults which might lead to the damage of the turbines. However, recently, the transmission system operators (TSOs) require to maintaining the connection of WTs with the grid to support the grid during fault and to assure the continuity of power supply. This requirement has been compiled in new grid codes in several countries. In this paper, super conducting magnetic energy storage (SMES) unit is used with two different types of variable speed wind turbine generators to comply with Spain grid codes. Results show that the low-voltage-ride-through (LVRT) of Type-3 and Type-4 wind turbine generators are significantly improved when SMES unit is connected to the system.

关键词： Wind turbines Coils Voltage fluctuations Generators Choppers Shafts Safety

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Application of STATCOM to improve the high-voltage-ride-through capability of wind turbine generator

Application of STATCOM to improve the high-voltage-ride-thro...

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IEEE Innovative Smart Grid Technologies - Asia (ISGT Asia)

作者： Y. M. Alharbi A. M. Shiddiq Yunus A. Abu-Siada King Abdullah scholarship program Australia Department of Mechanical Engineering Energy Conversion Study State Polytechnic of Ujungpandang Makassar Indonesia Department of Electrical and Computer Engineering Curtin University of Technology Perth WA Australia

Variable speed wind turbine with full scale converter or so-called type-D wind turbine generator worldwide installation has been significantly increased in the last few years. Voltage Swell in the grid side may cause the wind turbine to be disconnected from the grid. In this paper, STATCOM is applied to improve the high voltage ride through capability of type-D wind turbine during voltage swell in the grid side. Simulation is carried out using MATLAB/Simulink software. Results show that STATCOM can significantly improve the high voltage ride through (HVRT) capability of type-D wind turbine and prevents it from being disconnected from the grid during certain level of voltage swell in the grid side.

关键词： Automatic voltage control Wind turbines Educational institutions Reactive power Control systems Power system stability Wind energy

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Low-dimensional models from upper bound theory

Low-dimensional models from upper bound theory

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作者： Chini, Gregory P. Dianati, Navid Zhang, Zhexuan Doering, Charles R. Department of Mechanical Engineering University of New Hampshire Durham NH 03824 United States Center for Fluid Physics University of New Hampshire Durham NH 03824 United States Program in Integrated Applied Mathematics University of New Hampshire Durham NH 03824 United States Department of Physics University of Michigan Ann Arbor MI 48109-1040 United States Department of Mathematics University of Michigan Ann Arbor MI 48109-1043 United States Center for the Study of Complex Systems University of Michigan Ann Arbor MI 48109-1107 United States

A novel model reduction strategy for forced dissipative infinite-dimensional nonlinear dynamical systems is described. Unlike popular but empirical methods, this new approach does not require extensive data sets from experiments or direct numerical simulations of the governing field equations. Instead, truly predictive reduced dynamical models are constructed using Galerkin projection onto a priori eigenfunctions drawn from energy stability and upper bound theory. Within the context of porous medium convection, we show that these eigenfunctions contain information about boundary layers and other complex dynamic features and, thus, are well suited for the low-order description of highly nonlinear phenomena. Crucially, our analysis reveals the existence of a gap in the eigenvalue spectrumeven for strongly supercritical forcing conditionsenabling the identification of a rational truncation scheme. We demonstrate the efficacy of our approach via comparison with FourierGalerkin approximations of various orders. © 2010 Elsevier B.V. All rights reserved.

关键词： Chaos theory

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Transforming the academic workplace: An evaluation of the ADVANCE program in colleges of engineering (2001-2008)

Transforming the academic workplace: An evaluation of the AD...

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2010 ASEE Annual Conference and Exposition

作者： Zajicek, Anna M. Rencis, Joseph Morimoto, Shauna A. Hunt, Valerie H. Department of Sociology University of Arkansas United States Department of Mechanical Engineering University of Arkansas Fayetteville United States Department of Sociology and Criminal Justice University of Arkansas United States Doctoral Study in the Interdisciplinary Public Policy Program University of Arkansas Fayetteville United States

For over two decades, the US government has supported gender equity programs in Science, Technology, engineering, and Mathematics (STEM) disciplines. In 2001, the National Science Foundation (NSF) initiated the ADVANCE Institutional Transformation (IT) program with the primary goal to increase the representation of women in STEM. Since 2001, 37 institutions of higher education have received the NSF ADVANCE IT awards, and 19 have completed their five-year projects. Using the American Society of engineering Education (ASEE) data, we assess the changes in the representation of full-time tenure-track women faculty in engineering colleges. While earlier cross-institutional studies of the ADVANCE IT program focus only on ADVANCE institutions, we also compare engineering colleges at ADVANCE institutions to their university peers. Our analysis suggests that while the average gains in the percentage of full-time tenure-track engineering women faculty for Cohort 2 were almost twice the national average, the gains were uneven not only between the two cohorts, but also among the engineering colleges in each cohort. Similarly, the ADVANCE institutions showed an uneven performance when compared with their peers. We therefore raise important questions regarding how success is defined and conclude by highlighting the most interesting instances of successful and not so successful efforts along with the importance of conducting multi-level comparative analyses of ADVANCE and non-ADVANCE institutions. © American Society for engineering Education, 2010.

关键词： Professional aspects

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Exact constructions of a family of dense periodic packings of tetrahedra

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Physical Review E 2010年第4期81卷 041310-041310页

作者： S. Torquato Y. Jiao Department of Chemistry Princeton University Princeton New Jersey 08544 USA Department of Physics Princeton University Princeton New Jersey 08544 USA Princeton Center for Theoretical Science Princeton University Princeton New Jersey 08544 USA Program in Applied and Computational Mathematics Princeton University Princeton New Jersey 08544 USA School of Natural Sciences Institute for Advanced Study Princeton New Jersey 08540 USA Department of Mechanical and Aerospace Engineering Princeton University Princeton New Jersey 08544 USA

The determination of the densest packings of regular tetrahedra (one of the five Platonic solids) is attracting great attention as evidenced by the rapid pace at which packing records are being broken and the fascinating packing structures that have emerged. Here we provide the most general analytical formulation to date to construct dense periodic packings of tetrahedra with four particles per fundamental cell. This analysis results in six-parameter family of dense tetrahedron packings that includes as special cases recently discovered “dimer” packings of tetrahedra, including the densest known packings with density ϕ=40004671=0.856347…. This study strongly suggests that the latter set of packings are the densest among all packings with a four-particle basis. Whether they are the densest packings of tetrahedra among all packings is an open question, but we offer remarks about this issue. Moreover, we describe a procedure that provides estimates of upper bounds on the maximal density of tetrahedron packings, which could aid in assessing the packing efficiency of candidate dense packings.

关键词： constructions family tetrahedra tetrahedrons family Dense Platonic solid

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Optimal packings of superballs

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Physical Review E 2009年第4期79卷 041309-041309页

作者： Y. Jiao F. H. Stillinger S. Torquato Department of Mechanical and Aerospace Engineering Princeton University Princeton New Jersey 08544 USA Department of Chemistry Princeton University Princeton New Jersey 08544 USA Program in Applied and Computational Mathematics Princeton University Princeton New Jersey 08544 USA Princeton Center for Theoretical Science Princeton University Princeton New Jersey 08544 USA School of Natural Sciences Institute for Advanced Study Princeton New Jersey 08540 USA

Dense hard-particle packings are intimately related to the structure of low-temperature phases of matter and are useful models of heterogeneous materials and granular media. Most studies of the densest packings in three dimensions have considered spherical shapes, and it is only more recently that nonspherical shapes (e.g., ellipsoids) have been investigated. Superballs (whose shapes are defined by |x1|2p+|x2|2p+|x3|2p≤1) provide a versatile family of convex particles (p≥0.5) with both cubic-like and octahedral-like shapes as well as concave particles (0

关键词： Temperature

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Dense packings of polyhedra: Platonic and Archimedean solids

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Physical Review E 2009年第4期80卷 041104-041104页

作者： S. Torquato Y. Jiao Department of Chemistry Princeton University Princeton New Jersey 08544 USA Princeton Center for Theoretical Science Princeton University Princeton New Jersey 08544 USA Princeton Institute for the Science and Technology of Materials Princeton University Princeton New Jersey 08544 USA Program in Applied and Computational Mathematics Princeton University Princeton New Jersey 08544 USA School of Natural Sciences Institute for Advanced Study Princeton New Jersey 08540 USA Department of Mechanical and Aerospace Engineering Princeton University Princeton New Jersey 08544 USA

Understanding the nature of dense particle packings is a subject of intense research in the physical, mathematical, and biological sciences. The preponderance of previous work has focused on spherical particles and very little is known about dense polyhedral packings. We formulate the problem of generating dense packings of nonoverlapping, nontiling polyhedra within an adaptive fundamental cell subject to periodic boundary conditions as an optimization problem, which we call the adaptive shrinking cell (ASC) scheme. This optimization problem is solved here (using a variety of multiparticle initial configurations) to find the dense packings of each of the Platonic solids in three-dimensional Euclidean space R3, except for the cube, which is the only Platonic solid that tiles space. We find the densest known packings of tetrahedra, icosahedra, dodecahedra, and octahedra with densities 0.823…, 0.836…, 0.904…, and 0.947…, respectively. It is noteworthy that the densest tetrahedral packing possesses no long-range order. Unlike the densest tetrahedral packing, which must not be a Bravais lattice packing, the densest packings of the other nontiling Platonic solids that we obtain are their previously known optimal (Bravais) lattice packings. We also derive a simple upper bound on the maximal density of packings of congruent nonspherical particles and apply it to Platonic solids, Archimedean solids, superballs, and ellipsoids. Provided that what we term the “asphericity” (ratio of the circumradius to inradius) is sufficiently small, the upper bounds are relatively tight and thus close to the corresponding densities of the optimal lattice packings of the centrally symmetric Platonic and Archimedean solids. Our simulation results, rigorous upper bounds, and other theoretical arguments lead us to the conjecture that the densest packings of Platonic and Archimedean solids with central symmetry are given by their corresponding densest lattice packings. This can be regarded to be

关键词： Optimization

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Optimal Packings of Superdisks and the Role of Symmetry

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Physical Review Letters 2008年第24期100卷 245504-245504页

作者： Y. Jiao F. H. Stillinger S. Torquato Department of Mechanical and Aerospace Engineering Princeton University Princeton New Jersey 08544 USA Department of Chemistry Princeton University Princeton New Jersey 08544 USA Program in Applied and Computational Mathematics Princeton University Princeton New Jersey 08544 USA School of Natural Sciences Institute for Advanced Study Princeton New Jersey 08540 USA Princeton Center for Theoretical Science Princeton University Princeton New Jersey 08544 USA

Almost all studies of the densest particle packings consider convex particles. Here, we provide exact constructions for the densest known two-dimensional packings of superdisks whose shapes are defined by |x1|2p+|x2|2... 详细信息

关键词： Condensed matter physics

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Are concepts of technical & engineering literacy included in state curriculum standards? A regional overview of the nexus between technical & engineering literacy and state science frameworks

Are concepts of technical & engineering literacy included in...

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113th Annual ASEE Conference and Exposition, 2006

作者： Kochler, Cathi Giblin, David Moss, David M. Faraclas, Elias Kazerounian, Kazem University of Connecticut United States Neag School of Education University of Connecticut United States Galileo Program University of Connecticut United States Department of Education Neag School of Education University of Connecticut United States Study Abroad Program United Kingdom University of Connecticut School of Engineering Department of Electrical and Computer Engineering United States Instrument Manufacturing Company Storrs CT United States Department of Mechanical Engineering University of Connecticut United States ASME Robotics and Mechanisms Committee Galileo Project

The use of technology in the classroom has been a driving force behind developing a technically literate society. Reform documents such as Science for All Americans: Project 2061[1], Benchmarks for Scientific Literacy[2]and the National Science Education Standards [NSES][3]include sections titled, Science and Technology and The Nature of Technology, as a means to foster technical literacy for students in grades K-12. In NSES, the goal of the Science and Technology content standard is for all students to develop "abilities of technological design and understanding about science and technology." These reform documents have been the framework to foster science, technical and engineering literacy for students in grades K-12 across the United States as guided by their state science frameworks, however are states achieving this goal? Although these documents promote the need for understanding technology as it applies to science, how have states incorporated these principles into their own science curriculum standards? This investigation is part 2 of a multi-series project to understanding how public schools are training students to become technically literate. In part 1 presented at the 2005 ASEE Conference, we defined technical literacy to be "the ability of an individual to make informed decisions based upon an evolving understanding of the fundamentals of modern technologies." To accomplish this goal, we proposed the engineering Education Frameworks[5](EEF), which defined a pathway toward technical literacy for high school students. It was our intent to develop this set of guidelines to address technical literacy for secondary public schools. These Frameworks were designed to facilitate and promote the simultaneous teaching of multiple science disciplines in concert with mathematics while incorporating engineering concepts and designs. In part 2 of this project, we explore how various states in the United States include aspects of EEF in their science state frameworks

关键词： engineering education

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