国产精品第_久久精品国产一区二区三_99久精品_久久精品区_91视频18_国产91精品在线观看

VOA 学英语,练听力,上听力课堂! 注册 登录
> VOA > VOA常速英语-VOA Standard English > 2015年04月VOA常速英语 >  内容

VOA常速英语: 保持华盛顿领空安全是艰巨的任务

所属教程:2015年04月VOA常速英语

浏览:

2015年04月22日

手机版
扫描二维码方便学习和分享
https://online2.tingclass.net/lesson/shi0529/0009/9305/20150422_1.mp3
https://image.tingclass.net/statics/js/2012
Keeping Washington DC Airspace Safe Is Tall Order

WASHINGTON—Being the home of all three branches of the U.S. federal government makes Washington, D.C., the prime target for those who want to make their messages and ideas heard. Unfortunately, many of them choose to deliver them in unorthodox ways, including from the air, as a recent incident clearly showed involving a gyrocopter landing on the Capitol’s West Lawn.

When Florida Postal Service worker Doug Hughes landed his homemade gyrocopter on the west lawn of the U.S. Capitol, in a daring bid to deliver a political message to the lawmakers, the security services were taken by surprise.

 

He was quickly surrounded and taken away by police, his aircraft was checked for explosives, and now he faces several years of prison.

But his stunt highlighted once more that the airspace around most of the public buildings is easily penetrated by drones and light piloted aircraft, too small and flying too low to be safely prevented from reaching their goals.

Difficult detection

John Hansman a professor of Aeronautics and Astronautics at Massachusetts Institute of Technology, said small, flying vehicles are not easy to detect and stop.

“If you have a very small target, like a gyrocopter, which doesn't have a very large radar cross-section, so it's not reflecting much energy back, and it's close to the ground, you might get some signal coming there, but you may actually think it's a building or a car moving on the ground, not a helicopter," he said.

Hansman noted that heavy traffic in downtown Washington makes it even more difficult.

“If you have a complex environment like an area around Washington where you have lots of other vehicles on the ground, you have vehicles in the air, and you have something very small like this, it's actually not that difficult for it to slip through the protection,” said Hansman.

Inadequate systems

The chairman of the American Leadership and Policy Foundation, David Stuckenberg, is a former military pilot who writes about the airspace security. Speaking via Skype, he said the present safety systems are inadequate.

“We need to understand that we've been lucky and as technology increases and as drones proliferate people will increasingly look at these as weapons of opportunity or technologies that can be adapted for ill intent,” he said.

Stuckenberg said a lot more needs to be done before such systems are in place, such as conducting thorough analyses and bringing new regulations.

用户搜索

疯狂英语 英语语法 新概念英语 走遍美国 四级听力 英语音标 英语入门 发音 美语 四级 新东方 七年级 赖世雄 zero是什么意思十堰市果品巷英语学习交流群

  • 频道推荐
  • |
  • 全站推荐
  • 推荐下载
  • 网站推荐
主站蜘蛛池模板: 国产一区二区免费在线观看 | 亚洲免费专区 | 欧美色视频在线观看免费视频 | 嫩模精品福利视频在线 | 国产经典三级在线 | 亚洲免费视频免在线观看 | 亚洲图片小说网 | 亚洲欧美在线免费观看 | 日本啪啪片 | 伊人狠狠操| 国产乱妇无乱码大黄aa片 | 亚洲精品夜夜夜 | 日韩毛片一级 | 亚洲综合在线观看一区www | 女人高潮被爽到呻吟在线观看 | 男女裸体影院高潮 | 欧美一区二区三区在线观看免费 | 亚洲天堂在线视频 | 青青青在线视频人视频在线 | 久久久久人妻一区精品性色av | 亚洲国产精品一区二区不卡 | 爽爽爽爽爽爽a成人免费视频 | 男女生特黄的视频 | 成人福利视频在线观看网 | 在线观看成人免费视频 | 久久亚洲美女久久久久 | 欧美成人一区二区三区不卡视频 | 2021国产精品视频网站 | a级毛片高清免费视频 | 麻豆亚洲av永久无码精品久久 | 又紧又大又爽精品一区二区 | av无码久久久久不卡网站下载 | 4438xx亚洲最大五色丁香 | 国产91网站在线观看 | 国产97视频在线观看 | 中文字幕在线播放 | 55夜色66夜色国产精品视频 | 国产一级特黄aa大片高清 | 色噜噜狠狠色综合日日 | 欧美在线精品一区二区三区 | a大片大片网y |