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【关键字】考研
文登考研英语钻石卡（VIP）外报阅读第16期
Passage 1: Technology monitor
Misty aqua
May 3rd 2011, 13:19 by The Economist online
IN THE dry desert on the west coast of Namibia, where the annual average rainfall is a meagre 40mm, the Namib beetle (Stenocara gracilipes) has evolved a unique mechanism to drink. It collects moisture from the early-morning fog that is produced when ocean breezes from the Atlantic collide with the hot desert air. Drawing inspiration from the beetle’s fog-harvesting trick, Shreerang Chhatre, a graduate student at the Massachusetts Institute of Technology, and his colleagues have developed a simple and inexpensive way to produce drinking water.
The Namibia mist rapidly dissipates once the sun rises, so the beetle has just a brief opportunity to collect water. The insect typically finds a ridge of sand and faces the breeze, angling its lower body upwards with its specially adapted wings outstretched. The wings have bumps made of a hydrophilic substance that attracts minute water droplets. As they accumulate, the droplets grow larger until their weight causes them to run off into troughs in the beetle’s wings. These troughs are covered with a waxy water-repelling substance which has the effect of rolling the droplets down the beetle’s inclined body towards its mouth. The insect then promptly drinks them. Fog harvesting is not a new idea. FogQuest, a Canadian charity, has been installing devices using a plastic mesh to catch water droplets in developing countries for more than a decade. Mr Chhatre says what he and his colleagues have done is to increase the efficiency of water collection by using a variety of surface coatings.
Water droplets in fog are very small, typically between 1 to 50 microns (one-millionth of a metre). Hydrophilic surfaces gather and hold droplets with electrostatic attraction, which prevents them being picked up and carried away in the wind. As more droplets are attracted, they spread out and eventually join together and run off the surface—as they do on a pane of glass. Hydrophobic coatings, like Teflon, are then needed to
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repel the water and stream it as quickly as possible to a reservoir so that it is not lost to evaporation.
Mr Chhatre, a chemist, studied the so-called wettability of various coatings and found mathematical formulae which could determine the ideal combination of coatings for the different sizes of fog particles found in any particular region. The surface texture of the coatings also turned out to be important.
The ideal locations for fog harvesting are mountainous and desert regions where fog is present but water sources are far away. Mr Chhatre is setting up a pilot project in South Africa that will use some of the new techniques, and he is trying to organise another in India. Using a coated aluminium mesh, he conservatively estimates that it is possible to collect about one litre of water from a mesh of one square metre. Under ideal conditions, he says, that could increase by a factor of ten, plucking plenty of water from thin air, as it were.
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Passage 2： Mobile tracking
The Difference Engine: The spy in your pocket Apr 29th 2011, 9:00 by N.V. | LOS ANGELES
FOR those who managed to miss the “Locationgate” brouhaha last week, a brief recap. The story broke in the Wall Street Journal, which reported on how two British researchers had discovered a database file called “consolidated.db” that contained unencrypted details of the owners’ travels over the past year. The file, found in computers that had synched with Apple’s iPhones and iPads, contained a date-stamped log of the longitude and latitude coordinates of the various locations visited. Right or wrong, the conclusion was that Apple was tracking every move its customers made. An uproar erupted as a result, with demands by lawmakers that the company explain its actions forthwith.
On April 27th, Apple broke its week-long silence with a denial that its mobile devices were tracking customers, but then promised to fix the privacy issue that did not exist anyway. Coming out of medical leave to help squelch the imbroglio, Steve Jobs, Apple’s charismatic chief executive, admitted that the company had made a mistake in how it handled the location data on its iPhones and iPads. But in no way did the devices log users’ locations multiple times a day. The data found in the phones referred to the location of various cell towers, not the users, which could be as far as 100 miles away, said Apple. Even so, independent researchers were quick to point out that the data could still allow phones to be tracked to within 100 feet.
According to Apple, it was all a misunderstanding on the part of the two British researchers. The file they had stumbled upon, the company claimed, contained simply the locations of known WiFi hotspots and cell towers that had been downloaded from Apple. The location database on the company’s servers has been built up over the past year using “anonymous, crowd-sourced information” as millions of iPhone and iPad users unknowingly synched (via iTunes) the location details of cell towers and WiFi
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【考研】外报阅读16
