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标题: 【10.15】深圳场放狗 [打印本页]

作者: 悉尼全智贤 时间: 2019-10-15 20:47
标题: 【10.15】深圳场放狗
二战还是没能成功分手。。。Q50 V30 输血中的比较多。。月度中了两篇之后估计就掉库了

感谢论坛，希望大家都能尽快成功分手，LZ准备报名11.1三战啦，明天看看ESR到底是哪里出了问题

作者: fangchen616 时间: 2019-10-15 20:58
沙丘是哪一篇，没有找到哎～

作者: 悉尼全智贤 时间: 2019-10-15 21:05

fangchen616 发表于 2019-10-15 20:58
沙丘是哪一篇，没有找到哎～

https://forum.chasedream.com/thread-1352670-1-1.html 二十一

作者: 九宸 时间: 2019-10-15 21:18
DS:一个等腰直角三角形（英文建议记一下：isosceles right triangle）的面积是S 周长是T，一个长方形的面积也是S，问S是多少？
（1）S=T
（2）长方形的长边是4
请问第二个条件是怎么算的，条件不足啊感觉没法算

作者: 悉尼全智贤 时间: 2019-10-15 21:30

九宸发表于 2019-10-15 21:18
DS:一个等腰直角三角形（英文建议记一下：isosceles right triangle）的面积是S 周长是T，一个长方形的面积 ...

不好意思啊真的记不清了。。。不算难

作者: billyisfragile! 时间: 2019-10-15 21:31
One of the common assertions in the literature is that booming dunes are rare. The standard test of whether a  dune booms or not is to climb up to the top of a nearby slipface and forcefully dislodge sand with a boot. The Kelso Dunes in the Mojave Desert of California feature well-known booming sands, and the boot test often gives spectacular and memorable results (10). But not always. Booming dunes are temperamental, sometimes  booming, sometimes mute. Some days will find the Kelso sands uncooperatively silent. Moreover, some slipfaces on a nominally booming dune such as at Kelso can never be made to boom.

A laboratory test for booming would clearly be of  great value. Lewis showed that this was possible (7). He  noted that bags of sand brought back to Pretoria would  "roar" when disturbed. In this spirit, we collected one gallon plastic milk jugs of sand from a number of desert  dune sites and took them back to the laboratory. On the dunes that boomed when booted, it was discovered that  the loudest sounds are invariably produced near the  dune crests and that basal regions of the dune bark only weakly if at all. On the basis of this observation, samples  were collected from these two regions.

Another immediate and satisfying observation was  that when booming sand is introduced into a milk jug and sloshed back and forth, a definite rhythm, like  fingers on a washboard, is detectable in the vessel wall,  and a pleasing thrum issues from the bottle. Thus a test  of laboratory-sized samples became available which  gives a definite signal, thrumming, when applied to  samples of known booming sand but which produces  only an uninspiring hiss from silent sand. The bottle test  was subsequently refined to the beaker test, as described below.

As Criswell (5), Lewis (7), and earlier authors had  observed, the booming property of a known booming  dune is strongly affected by the moisture content of the sand. When damp, the booming dunes fall silent. Even  when to the eye and touch the dune surface appears to have dried, it will remain silent until such time has  passed at a sufficiently low humidity that most adsorbed water has evaporated. Although not explaining why  some dunes never boom, the moisture effect is an obvious explanation of why booming dunes appear to be temperamental; adsorbed moisture on grain surfaces is often undetectable in the field, and yet it can choke off booming entirely. We note, however, the existence of  booming beach dunes, such as those south of the Napali Cliffs on the island of Kauai, Hawaii, which are certainly never as dry as desert sands (6, 11);  these dunes are calcareous, not quartzitic, and evidently the environmental conditions for booming are  dependent on the nature of the constituent grains. This observation suggests that the booming property is determined by a particular grain grain contact force which is attained without water for clean quartz grains, but requires some water adsorption for the calcareous sand.

作者: 泼盎胖 时间: 2019-10-19 17:00
hi 楼主
想请问一下
DS:M N P三个非空集合，M是P的子集问N∩P是否为非空集？
(1)N是P的子集
（2）P-M是空集
选C

这一题 1 为什么不行？

作者: 悉尼全智贤 时间: 2019-10-19 21:39

bzy! 发表于 2019-10-15 21:31
One of the common assertions in the literature is that booming dunes are rare. The standard test of ...

emm可能是记错了。。题目应该是M∩P？

作者: 泼盎胖 时间: 2019-10-20 20:41

悉尼全智贤发表于 2019-10-19 21:39
emm可能是记错了。。题目应该是M∩P？

哈哈哈哈好滴~~ 还好我又点进来看啦~
谢谢楼主是我问的

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