共查询到20条相似文献,搜索用时 15 毫秒
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《Change》2012,44(5):36-42
The polls and surveys have done their work. The commentators have pronounced, some with despair and some with delight, that the often raucous student voices of the sixties are muted. But Change believes in returning to the source, in hearing what the young people in our colleges are saying and in listening to how they say it. So we asked four students at Princeton University to talk with each other and with us about their sense of themselves as students, as people preparing for lives in a complex and difficult world. Andrew Christie, from Wilmington, Delaware, class of '74, majors in mathematics and philosophy. Jeremy Nobel, from Pittsburgh, Pennsylvania, class of '76, is concentrating on chemistry and creative writing. Margit Roos, from Nashville, Tennessee, class of '75, is undecided in her major but leaning toward economics. Judith Wasserheit, from New York City, class of '74, majors in biochemistry and Russian. The portions of their discussion that we publish here at the very least belie the charge that students today are self-satisfied and crass, that the idealism that brought campuses of the sixties to such vibrant life is merely a relic of history. 相似文献
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We study the dynamics of the space debris in the 1:1 and 2:1 resonances, where geosynchronous and GPS satellites are located. By using Hamiltonian formalism, we consider a model including the geopotential contribution for which we compute the secular and resonant expansions of the Hamiltonian. Within such model we are able to detect the equilibria and to study the main features of the resonances in a very effective way. In particular, we analyze the regular and chaotic behavior of the 1:1 and 2:1 resonant regions by analytical methods and by computing the Fast Lyapunov Indicators, which provide a cartography of the resonances. This approach allows us to detect easily the location of the equilibria, the amplitudes of the libration islands and the main dynamical stability features of the resonances, thus providing an overview of the 1:1 and 2:1 resonant domains under the effect of Earth’s oblateness. The results are validated by a comparison with a model developed in Cartesian coordinates, including the geopotential, the gravitational attraction of Sun and Moon and the solar radiation pressure. 相似文献
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The lump solutions and interaction solutions are mainly investigated for the -dimensional KPI equation. According to relations of the undetermined parameters of the test functions, the N-soliton solutions are showed by computations of the Maple using the Hirota bilinear form for -dimensional KPI equation. One type of the lump solutions for -dimensional KPI equation has been deduced by the limit method of the N-soliton solutions. In addition, the interaction solutions between the lump and N-soliton solutions of it are studied by the undetermined interaction functions. The sufficient conditions for the existence of the interaction solutions are obtained. Furthermore, the new breather solutions for the -dimensional KPI equation are considered by the homoclinic test method via new test functions including more parameters than common test functions. 相似文献
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《Change》2012,44(3):33-41
As recently as last year, I thought that “education”—the discipline—was too tiresome a subject to sustain my interest for more than a moment or two. I hastily abandoned this conviction after five minutes in front of a classroom. As a teacher, or as someone trying to teach, education became for me a living thing. By happy, unplanned circumstance, my teaching and the research for this project began at the same time. The two assignments have dovetailed in a way that no amount of planning could have forecast. This article is written from a black perspective—something which does not necessarily reside within a black skin. Retaining this perspective, particularly as a writer, requires among other things an agonizing bending of the mind. One is constantly obliged to see and weigh things including black education—from several points of view and finally to ask: “What does this or that event mean for black people at large—for ‘the movement’?“ The necessity for all of this is not readily understood by white people. The fact is that to be black in this country is to be part of “the movement.” Whether one is conscious of this fact or not, whether one rushes out to “join” something or not, matters little. One belongs whether one is male or female, unemployed, skilled in carpentry, or deep in clinical psychology. One “withdraws” from the movement only at great psychic cost. To be in it is painfully expensive as well, but this pain is offset by that particular joy that comes from embracing one's own people. 相似文献
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Leo G II Chouinard 《International Journal of Mathematical Education in Science & Technology》2013,44(3):451-459
Setting up iterated integrals is only approached graphically in standard calculus textbooks. However, for three-dimensional regions of integration in particular, the graphics shown in textbooks are often not capable of reproduction by students. This article explains an algebraic approach to setting up iterated integrals that has been used by the author for about 15 years to bypass or simplify graphing difficulties in these problems. 相似文献