Less Is More
It sounds all wrongdrilling holes in a piece of wood to make it more resistant to knocks. But it works because the energy from the blow gets distributed throughout the wood rather than focusing on one weak spot. The discovery should lead to more effective and lighter packaging materials.
Carpenters have known centuries that some woods are tougher than others. Hickory , for example, was turned into axe handles and cartwheel spokes because it can absorb shocks without breaking. White oak, for example, is much more easily damaged it is almost as dense. Julian Vincent at Bathe University and his team were convinced the woods internal structure could explain the differences.
Many trees have tubular vessels that run the trunk and carry water to the leaves. In oak they are large, and arranged in narrow bands, but in hickory they are smaller, and more evenly distributed. The researchers this layout might distribute a blows energy throughout the wood, soaking up a bigger hit. To test the idea, they drilled holes 0.65 millimetres across into a block of spruce , a wood with vessels, and found that withstood a harder knock. when there were more than about 30 holes per square centimetre did the woods performance drop off.
A uniform substance doesnt cope well with knocks because only a small proportion of the material is actually . All the energy from the blow goes towards breaking the material in one or two places, but often the pieces left are pristine .
But instead of the energy being concentrated in one place, the holes provide many weak spots that all absorb energy as they break, says Vincent. You are controlling the places the wood breaks, and it can then absorb more , more safely.
The researchers believe the principle could be applied to any material- example, to manufacture lighter and more protective packaging. It could be used in car bumpers, crash barriers and armour for military vehicles, says Ulrike Wegst, the Max Plank Institute for Mental Research in Stuttgart. But she emphasizes that you to design the substance with the direction of force in mind. The direction of loading is crucial, she says.
1 A in B since C for D at
2 A or B although C and D despite
3 A down B over C up D into
4 A knew B concluded C saw D thought
5 A no B per C each D every
6 A it B the idea C they D spruce
7 A If B Just C Only D Rarely
8 A effected B beaten C slapped D affected
9 A behind B beyond C for D in
10 A which B there C that D where
11 A water B air C energy D safety
12 A among B in C as D for
13 A also B besides C else D yet
14 A over B at C around D on
15 A have B must C should D had
【参考答案】
1. C 2. B 3. C 4. D 5. A
6. A 7. C 8. D 9. A 10. D
11. C 12. D 13. A 14. B 15. A
Build up our mind
欧洲商学院寻找发展亮点
不能改天的约会
How to Live Beautifully
Helpless love
澳洲富豪与中信泰富因采矿权起纠纷
The Sound of Music 音乐之声
The Happy Marriage
全球氦气供应短缺
Smile 微笑
A Good Lesson
Letting Go of Yesterday
Youth is a state of mind
Don't Let Weakness Limit Your possibilities
魔镜魔镜告诉我,今天天气怎么样
印度也爱上了葡萄酒
企业不必雇佣多面手
澳门马拉松赛程失误考验选手耐力
台风侵袭菲律宾超过200人死亡
Rain of Seattle 2
卡尼面临的挑战
全球页岩气开发遇阻
中概股在美受挫 美国交易所被批看门不力
2013年可以出手买房了?
The Power of actions
Reading
巴西世界杯能"干净"吗?
一心想成功会让我们输掉什么?(陈愉)
悟透“自己”
Put the goal in your heart
不限 |
英语教案 |
英语课件 |
英语试题 |
不限 |
不限 |
上册 |
下册 |
不限 |