tailieunhanh - The Coming of Materials Science p3

Công nghệ cơ khí thường tạo ra các giả lập mô phỏng hoạt động của các đối tượng, như quy trình chế tạo thực tế theo trình tự tối ưu hóa sự thực hiện, hiệu quả kinh tế và chi phí năng lượng trước khi quyết định lựa chọn một thiết kế cụ thể. | 60 The Coming of Materials Science Figure . from Emerson p. 134 Possible arrangements of spherical particles according to Hooke left from a republication in Micrographia Restaurata. London 1745 and Huygens right from Trade de ta Lumière Leiden 1690 . Kepler 1571-1630 had made similar suggestions some decades earlier. Both Kepler and Huygens were early analysts of crystal symmetries in terms of atomic packing. This use of undifferentiated atoms in regular arrays was very different from the influential corpuscular models of René Descartes 1596-1650 as outlined by Emerton 1984 p. 131 et seq. Descartes proposed that crystals were built up of complicated units star- or flower-shaped for instance in irregular packing according to Emerton this neglect of regularity was due to Descartes s emphasis on the motion of particles and partly because of his devotion to Lucretius s unsymmetrical hook-and-eye atoms. In the 18th century the role of simple spherical atoms was once more in retreat. An eminent historian of metallurgy Cyril Stanley Smith in his review of Emerton s book Smith 1985 comments .corpuscular thinking disappeared in the 18th century under the impact of Newtonian anti-Cartesianism. The new math was so useful because its smoothed functions could use empirical constants without attention to substructure while simple symmetry sufficed for externals. Even the models of Kepler Hooke and Huygens showing how the polyhedral form of crystals could arise from the stacking of spherical or spheroidal parts were forgotten. The great French crystallographers of that century Rome de risle and Haiiy thought once again in terms of non-spherical molecules shaped like diminutive crystals and not in terms of atoms. Jean-Baptiste Rome de 1 Isle 1736-1790 and René Haiiy 1743-1822 while they as remarked credited Linnaeus with the creation of quantitative crystallography themselves really deserve this accolade. Rome de 1 Isle was essentially a chemist and much concerned with the .