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仓储规划和物资储存计划实际上是同一概念，都是对库存物资进行安排和计划。 ()
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分析各个对象在物流市场中所占的份额，并提出对应不同对象的战略和策略方案的分析方法，称为时间结构分析。 ()
The word holiday originally meant holy day; but now the word signifies any day on which we
In 1990, the brothers successfully tested their 50-pound biplane glider in Carolina, and subsequently made a number of revisions. Controlled, powered flight had seemed impossible until Orville Wright took off on the 17th, December 1903. The key to the Wright Brothers' success was that their engineering had gone beyond the trial and error methods of their contemporaries.
Having only very limited resources they showed great scientific ingenuity. When their test flights did not produce as much lift as they had expected, they went back to first principles and carried out a series of scientific experiments, starting with the bicycle balance and moving on to their famous wind tunnel experiments. They were the first to understand how the lift from the aerofoil changes in flight, and the first to design their propellers as a form. of aerofoil.
Despite the financial burdens of all their research, testing, and the many aircraft built, the Wright Brothers were never financed by outsiders. The bicycle was a hot item at that time, and their bicycle shop financed everything. The first passenger to ever fly in an airplane was Charles W. Furnas who was taken aloft by Wilbur Wright on May 14, 1908 for a flight of 28.6 seconds duration. Orville and Wilbur flew together only once in their airplane for their father to see, but decided it unwise, because if they crashed, no one could carry on their work.
The Wright Brothers inherited an aptitude for independent judgment, personal courage and mechanical talents of superior caliber. Two older brothers, Reuchlin and Lorin and a sister Katharine, went on to college, while Orville and Wilbur had only high school educations, and never officially graduated. However, their solid scientific methods had set free the ancient dream of human flight. The first American to fly after the Wright Brothers was Glenn H. Curtiss, who flew his "June Bug" for the first time on June 20, 1908. The first airplane purchased by the American Government was a Wright Biplane.
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Then in the early 1950s Emiliani produced the first complete record of the waxings and wanings of past glaciations. It came from a seemingly odd place. The seafloor single-cell marine organisms called "foraminifera" house themselves in shells made from calcium carbonate. When the foraminifera die, sink to the bottom, and become part of seafloor sediments, the carbonate of their shells preserves certain characteristics of the seawater they inhabited. In particular, the ratio of a heavy isotope of oxygen (oxygen-18) to ordinary oxygen (oxygen-16) in the carbonate preserves the ratio of the two oxygens in water molecules.
It is now understood that the ratio of oxygen isotopes in seawater closely reflects the proportion of the world's water locked up in glaciers and ice sheets. A kind of meteorological distillation accounts for the link. Water molecules containing the heavier isotope tend to condense and fall as precipitation slightly sooner than molecules containing the lighter isotope. Hence, as water vapor evaporated from warm oceans moves away from its source, its oxygen-18 returns more quickly to the oceans than does its oxygen-16. What falls as snow on distant ice sheets and mountain glaciers is relatively depleted of oxygen-18. As the oxygen-18-poor ice builds up the oceans become relatively enriched in the isotope. The larger the ice sheets grow, the higher the proportion of oxygen-I 8 becomes in seawater—and hence in the sediments.
Analyzing cores drilled from seafloor sediments, Emiliani found that the isotopic ratio rose and fell in rough accord with the Earth's astronomical cycles. Since that pioneering observation, oxygen-isotope measurements have been made on hundreds of cores. A chronology for the combined record enables scientists to show that the record contains the very same periodicities as the orbital processes. Over the past 800,000 years, the global ice volume has peaked every 100,000 years, matching the period of the orbital eccentricity variation. In addition, "wrinkles" superposed on each cycle-small-decrease or surge in ice volume have come at intervals of roughly 23,000 and 41, 000 years, in keeping with the precession and tilt frequencies of the Earth's spin axis.
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