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2017年10月23日 06:55:42|来源:国际在线|编辑:飞度新闻养生问答网
Science and technology科学技术Cryptography密码术The solace of quantum量子之慰Eavesdropping on secret communications is about to get harder现在想窃听秘密联系会越来越难CRYPTOGRAPHY is an arms race between Alice and Bob, and Eve.艾莉斯,鲍伯和伊芙之间正在进行一场密码术的军备竞赛。These are the names cryptographers give to two people who are trying to communicate privily, and to a third who is trying to intercept and decrypt their conversation.这里所说的艾莉斯,鲍伯和伊芙是译解密码者的代号,前两位在努力进行秘密联系,而第三位伊芙则试图阻止他们的联系,并且在尽力破解他们的联系密码,希望能够知道联系的具体内容。Currently, Alice and Bob are ahead—just.目前,艾莉斯和鲍伯只是暂时领先,But Eve is catching up.但是伊芙正在迎头赶上。Alice and Bob are therefore looking for a whole new way of keeping things secret.因此,艾莉斯和鲍伯正在寻找另一种全新的联系方式,以保他们联系的秘密性。And they may soon have one, courtesy of quantum mechanics.借助于量子力学,他们可能很快就会找到。At the moment cryptography concentrates on making the decrypting part as hard as possible.眼下,密码系统正集中力量让解密部分尽可能地难以实施。The industry standard, known as RSA , relies on two keys, one public and one private.被称为RSA的行业标准,取决于两种密钥,一种是公开密钥,另一种是秘密密钥。These keys are very big numbers, each of which is derived from the product of the same two prime numbers.这此密钥都是非常庞大的数字,每一个都来源于两个相同素数的乘积。Anyone can encrypt a message using the public key, but only someone with the private key can decrypt it.任何人都可以使用公开密钥加密消息,但只有拥有秘密密钥的人才能解密。To find the private key, you have to work out what the primes are from the public key.为了找到这个秘密密钥,人们不得不进行大量的运算,从公开密钥中找到这两个素数。Make the primes big enough—and hunting big primes is something of a sport among mathematicians—and the task of factorising the public key to reveal the primes, though possible in theory, would take too long in practice.虽然,从理论上讲,1、要保素数足够大—发现大的素数是数学家们热衷的一种游戏,2、对公开密钥进行因式分解希望找到这些素数,这两项任务是可能的,但是在实际中将会花费很长时间。Since the 1970s, though, the computers that do the factorisation have got bigger and faster.但是,从二十世纪七十年代以来,能够进行因式分解的电脑越来越大,速度越来越快。Some cryptographers therefore fear for the future of RSA.一些密码破译者因此开始担心RSA的未来。Hence the interest in quantum cryptography.因此,他们把眼光放到了量子密码术上。Alice, Bob and Werner, too?艾莉斯,鲍伯,沃莫也这样吗?The most developed form of quantum cryptography, known as quantum key distribution, relies on stopping interception, rather than preventing decryption.量子密钥分配是量子密码学最流行的方式,它主要是依靠阻止拦截,而不是防止解密上。Once again, the key is a huge number—one with hundreds of digits, if expressed in the decimal system.这个系统的密钥还是一个庞大的数字—如果以十进制表示的话,一个就有几百个数字。Alice sends this to Bob as a series of photons before she sends the encrypted message.艾莉斯在发送加密信息之前,会先发送一系列的光量子给鲍伯。For Eve to this transmission, and thus obtain the key, she must destroy some photons.因为伊芙要想读到这个信息,从而获得密钥,她必须要破坏一些光量子。Since Bob will certainly notice the missing photons, Eve will need to create and send identical ones to Bob to avoid detection.因为鲍伯肯定会注意到这些消失的光子,伊芙就必须创造并向鲍伯发送相同的光子,才能不会被发觉。But Alice and Bob can stop that by using two different quantum properties, such as the polarities of the photons, to encode the ones and zeros of which the key is composed.但是艾莉斯和鲍伯通过将两种不同属性—比如不同极性的光子--的量子转译成1和0,以阻止伊芙的拦截。According to Werner Heisenbergs Uncertainty Principle, only one of these two properties can be measured, so Eve cannot reconstruct each photon without making errors.根据海森堡的不确定性原理,伊芙只能捕捉到这两种不同属性光子中的一种,所以她无法完全再造出一模一样的光子。If Bob detects such errors he can tell Alice not to send the actual message until the line has been secured.如果鲍伯发现这种错误的话,他就会通知艾莉斯,在通信渠道安全之前,不要发送真正的信息。One exponent of this approach is ID Quantique, a Swiss firm.运用这种编码方式的典型代表是一家叫ID Quantique的瑞士公司。In collaboration with Battelle, an American one, it is building a 700km fibre-optic QKD link between Battelles headquarters in Columbus, Ohio, and the firms facilities in and around Washington, DC.在与一家名称巴特尔的美国公司合作过程中,该公司在巴特尔位于俄亥俄州哥伦布市的总部,和该公司在华盛顿特区附近及市区的工厂之间,建立了一条700公里的光纤量子密码的链接。Battelle will use this to protect its own information and the link will also be hired to other firms that want to move sensitive data around.巴特尔将使用这个光子链接来保护它的自身信息,同时这个链接也会在其它打算频繁交换信息的公司中使用。QuintessenceLabs, an Australian firm, has a different approach to encoding.一家名叫QuintessenceLabs的澳大利亚公司的编码方式却不一样。Instead of tinkering with photons polarities, it changes their phases and amplitudes.这家公司并没有在光子的极性上做文章,而是改变了它们的相位和振幅。The effect is the same, though: Eve will necessarily give herself away if she eavesdrops. Using this technology, QuintessenceLabs is building a 560km QKD link between the Jet Propulsion Laboratory in Pasadena, California, which organises many of NASAs unmanned scientific missions, and the Ames Research Centre in Silicon Valley, where a lot of the agencys scientific investigations are carried out.但是结果却是一样:如果伊芙窃听的话,她肯定会露出马脚的。该公司正使用这个技术,在加利福尼亚州帕萨迪纳市的喷气推进实验室—该实验室组织了多次美国航空航天局无人驾驶的科研任务,和进行大量机构科学调查的硅谷艾姆斯研究中心之间建立一条560公里的QKD链接。A third project, organised by Jane Nordholt of Los Alamos National Laboratory, has just demonstrated how a pocket-sized QKD transmitter called the QKarD can secure signals sent over public data networks to control smart electricity grids.量子运用于密码术上的第三个项目,则是由洛斯阿拉莫斯国家实验室的简-纳德特组织的。这个项目演示了,一个口袋大小的称为OKarD的QKD发报机是如何捕捉发送到公共数据信息网的信号,来控制智能电网的。Smart grids balance demand and supply so that electricity can be distributed more efficiently.智能电网可以平衡电力供应与需求,从而让电力分配更有效。This requires constant monitoring of the voltage, current and frequency of the grid in lots of different places—and the rapid transmission of the results to control centres.这需要对不同地区电网的电压,电流和频率进行不间断地监测,同时监测结果要快速地传回到控制中心。That transmission, however, also needs to be secure in case someone malicious wants to bring the system down.然而,也需要确保这种传输的安全,以防某些人恶意地破坏这个系统。In their different ways, all these projects are ambitious.虽然他们防止窃听的方式不一样,但是这些项目都充满着远大的抱负。All, though, rely on local fixed lines to carry the photons.但是,它们都要依靠当地固定的线路来传送光子。Other groups of researchers are thinking more globally.另外一些研究者的思维则更加全球化。To do that means sending quantum-secured data to and from satellites.要想达到这些研究者的要求,就必须通过卫星来传送量子安全信息。At least three groups are working on this: Thomas Jennewein and his team at the Institute for Quantum Computing in Waterloo, Canada; a collaboration led by Anton Zeilinger at the University of Vienna and Jian-Wei Pan at the University of Science and Technology of China; and Alex Ling and Artur Ekert at the Centre for Quantum Technologies in Singapore.现在至少有三个研究团体都在进行着这方面的研究。分别是加拿大滑铁卢的量子研究所托的马斯-詹内怀恩和他的团队,维也纳大学的安东-塞林格和中国科技大学的潘建国为首的合作团队,还有新加坡量子技术中心的阿莱克斯-林和阿图-恩科特团队。Dr Jenneweins proposal is for Alice to beam polarisation-encoded photons to a satellite.詹内怀恩士的计划建立在以艾莉斯为基础上的,她计划发送偏振编码的光子给卫星。Once she has established a key, Bob, on another continent, will wait until the satellite passes over him so he can send some more photons to it to create a second key.一旦她建立起一个密钥,那么当卫星运行到位于另一个大陆的鲍伯附近时,鲍伯就可以发送更多的光子给它,就建立起了第二个密钥。The satellite will then mix the keys together and transmit the result to Bob, who can work out the first key because he has the second.卫星届时会把这两个密钥混合起来,再把结果传输给鲍伯,拥有第二个密钥的鲍伯就可以解开第一个密钥。Alice and Bob now possess a shared key, so they can communicate securely by normal terrestrial networks.艾莉斯和鲍伯则会拥有一个共享密钥,所以他们能够通过正常的地面网络进行安全地联系。Dr Jennewein plans to test the idea, using an aircraft rather than a satellite, at some point during the next 12 months.詹内怀恩士计划在未来一年内的某个时候,用飞机,而不是卫星测试一下这个想法。An alternative, but more involved, satellite method is to use entangled photon pairs. Both Dr Zeilingers and Dr Lings teams have been trying this.一个更复杂的卫星方法是运用混杂在一起的光子对。塞林格士和林士所领导的两个团队一直专攻于这个方向。Entanglement is a quantum effect that connects photons intimately, even when they are separated by a large distance.量子缠结是一种即使光子相隔很远也能快速连接的量子效应。Measure one particle and you know the state of its partner.如果能测到一个粒子,你就能知道它同伴的状态。In this way Alice and Bob can share a key made of entangled photon pairs generated on a satellite.通过这种方式,艾莉斯和鲍伯能够共享一个在卫星上产生的,缠结光子对组成的密钥。Dr Zeilinger hopes to try this with a QKD transmitter based on the International Space Station.寒林格士希望能够用国际空间站的QKD发射器进行这项试验。He and his team have been experimenting with entanglement at ground level for several years.他和他的团队在地面上进行这种缠结试验已经几年了。In 2007 they sent entangled photon pairs 144km through the air across the Canary Islands.2007年,他们利用空气让光子对穿过了加那利群岛,传输了144公里。Dr Lings device will test entanglement in orbit, but not send photons down to Earth.林士的设备将会在轨道上测试缠结效应,但是不会把光子传回到地球。If this sort of thing works at scale, it should keep Alice and Bob ahead for years.如果这方面工作的规模不断扩大,那么艾莉斯和鲍伯将会保持领先很多年。As for poor Eve, she will find herself entangled in an unbreakable quantum web.对于可怜的伊芙来说,她会发现自己身陷于一个牢不可破的量子网中无法解脱。 /201311/265455Science and technology科学技术Marine technology船舶技术A voyage of discovery探索未知之旅New technology can make ships more versatile, more efficient and cleaner, too新技术使轮船更万能、更也更环保IN THE days when Norsemen pillaged their way around the monasteries and villages of Europe, Norwegian shipwrights were at the forefront of naval architecture.早在北欧人大肆掠夺欧洲的修道院和村庄时 ,挪威的造船工人就已在造船技术方面跻身前列。They still are.现在他们仍然处于世界领先水平。Norway is an important centre of marine innovation and several foreign companies have operations there, too.挪威是重要的船舶创新中心,一些外国公司也在这里设有分公司。One such is the marine division of Rolls-Royce, a British firm, which is collaborating with Farstad, a shipping company based in Alesund, and STX OSV, a shipbuilder.其中一家便是劳斯莱斯公司在这里设立的海运部,这家英国公司与总部设在阿雷松德的Farstad航运公司以及STX OSV造船公司都拥有合作关系,The result of their efforts is Far Solitaire, the first of a new class of vessels which bristle with novel technology that promises to make shipping safer, cleaner and cheaper.而他们三强通力合作的成果便是远航明珠舰。它是一批新式轮船中第一艘运用大量创新技术的船,这些技术使得船运更安全、更环保/清洁、更低廉。Far Solitaire has been designed as a platform-supply ship for the North Seas oil and gas industry.远航明珠舰是为了发展北海石油和天然气开采业而设计的一艘平台供给轮船。This means she is not a large vessel.这意味着它的体型并不大。She is 91 metres long, has a deadweight of 5,700 tonnes and cost about 70m.它长91米,载重量为5700公吨,总造价约7000万美元。But some of the innovations she uses should be applicable to vessels of all sizes.但是设计该船时所运用的一些创新技术却适用于任何大小的船只。At the moment she is being fitted out by STX OSV at its Langsten shipyard on Tomrefjord.目前这艘轮船还停泊在Tomrefjord的Langsten造船厂由STX OSV公司完成装配工作。In October she will be delivered to Farstad, who will use her to supply rigs in the regions notoriously heavy seas.今年十月,它将被交付给Farstad公司,该公司会用它在波涛汹涌北海运送钻探设备。Crucially, she has to be able to hold her position while transferring cargoes that include various noxious materials which are employed in drilling or pumped into wells to improve the process of extraction.最关键的是,它必须在转移货物时保持平稳。这些货物包含了各种有毒物质,将用于钻井或用泵注入油井中以优化石油提取过程。These have to be delivered to and removed from the platforms.它们必须由船只运到钻井平台上,使用完后再运离平台。Such transfers are potentially hazardous for the people involved and for the environment.这种运输过程对参与者以及环境都存在着潜在的危险。One of Far Solitaires most important innovations is her wave-piercing hull. Below the waterline her bow has the bulbous drag-reducing nose that has become a familiar feature of modern ships.远航明珠舰所使用的最重要的一项创新技术就是它的穿浪型船体。该轮船的吃水线下面有一个球形的“大鼻子”用来减少波浪带来的阻力,这对现代轮船来说并不是什么稀奇的特点,Above it, however, things are all new.但它球鼻上方的构造却是十分新鲜。Where a standard ships bow would have a flat foredeck, Far Solitaires flows up and over the vessel.按标准结构来说,轮船的船头通常都有一块平坦的前甲板,而远航明珠舰的船头却向上突起,高过船身。This means that instead of riding the waves, as most ships do, she can penetrate them.这意味着与其它的乘浪行驶的轮船不同,远航明珠舰能破浪行驶。That is a crucial change.这是一个十分重要的改变。When a ship rides the waves her engines slow down and then surge as her hull rises and falls.当一艘船乘浪行驶时它的引擎转速会随着船体的上下颠簸而加快或变慢/它的引擎会随着船体的上下颠簸或减速或加速。By piercing the swell, Far Solitaire will be able to maintain her engines at a constant speed.远航明珠舰能破开涌动的海浪从而使它的引擎维持常速工作。This will cut fuel consumption, reduce wear and tear, and make life for the crew safer and more comfortable.这一改变能降低轮船的油耗,减少轮船的磨损,同时使船员更加安全舒适。Future shipshape未来新船舶技术Far Solitaire is powered by a conventional diesel-electric system consisting of three engines connected to generators that run electric motors.远航明珠舰由一个传统的柴电推进系统驱动,该系统由三个引擎组成,而这三个引擎又与运行着马达的发电机相连接。The thrusters which those electric motors drive, however, are anything but conventional.但是那些马达所驱动的推进器却远非寻常。The main pair are stern-mounted Azipull propellers. These are similar to the azimuth thrusters aly used on some vessels: propellers on pods that can be rotated to push the ship in different directions, making a rudder unnecessary.其中最重要的一对是安装在船尾的Azipull螺旋桨,它们与一些轮船已经在使用的方位推进器有点相似:分离舱上可旋转的螺旋桨能够推动船驶向不同的方向,这样就不必再使用船舵。But the Rolls-Royce Azipull has the propeller at the front of the pod rather than the back.但是劳斯莱斯公司将Azipull螺旋桨装在了分离舱的前端而非尾部,That means the propeller operates in a smoother flow of water, which improves efficiency and assists steering.这意味着螺旋桨能在更平稳的水流中工作,从而提高效率,方便轮船的行驶。This design has been made possible using computational fluid dynamics to perfect the shapes of the blades and pods.设计师通过计算流体力学完善舵叶与分离舱的形状,使得这种设计成为可能。Further control is provided by two bow thrusters. These are propellers mounted in transverse tunnels in the hull, to help position the craft and hold her stable while alongside a rig.其他操控设备还有船首侧推装置,它是安装在船体横向通道中的两个推进器,用来帮助轮船进行定位并在船上装载钻探时保持船体平稳。And there is also an azimuth thruster that can be swung down from the forward part of the hull if an extra push is required.另外在需要额外推力时还有方位推进器可从船体前方摆下。All of these propulsion systems are handled by moving one of the joysticks next to the captains chair in a bridge with a 360° view that looks more suitable for the starship Enterprise than what is, after all, a souped-up freighter.船长只要移动驾驶室座椅边的操纵杆就能控制这些推进装置,这个拥有360°全方位视角的驾驶室看起来更适合进取号星舰,而不仅仅是普通的货船,因为后者只不过是加了马力的船舶而已。The consequences of moving the joystick can, fortunately, be practised on shore without risk to ship or platform, courtesy of a new 360° bridge simulator in Rolls-Royces marine-training centre in Alesund.幸好移动操控杆的效果能在阿雷松德船舶训练中心进行试验,劳斯莱斯公司在这里建有一个360°全方位视角的模拟驾驶室,有了岸上的训练就能避免给轮船和钻井平台带来危险。The captain can also call on the assistance of an electronic positioning system that uses a combination of data from satellites, gyrocompasses, and wind and motion sensors to operate the thrusters automatically.另外,船长还能从电子定位系统中获取帮助,该系统能结合卫星、回转罗盘、风能和运动传感器三者的数据自动操控推进器。Solid freight is carried on a deck that has an area of 1,020 square metres.固体货物会被安置在一个面积达1020平方米的甲板上,Liquids, meanwhile, are stored below deck in tanks, each of which is fitted with its own pumping system, in order to avoid the risk of mixing substances best kept separate.而液体货物则会被存储在甲板下的液货舱中,每种液体对应相应的抽运系统以避免不宜混合放置的液体搅拌在一起。Borge Nakken, who is in charge of technology and development at Farstad, expects Far Solitaire to use about 40% less fuel than a conventional vessel of the same size that is carrying out similar tasks.Borge Nakken是Farstad公司技术与发展部门的负责人,他预期,在执行相似任务时,远航明珠舰的耗油量将比同样大小的传统型轮船少40%,This is a remarkable saving, and although she is a small, specialist vessel, many of her features, particularly the new bow and the more efficient system of propellers, could help reduce fuel consumption and emission levels in larger ships as well.其耗油量的减少是十分显著的。尽管远航明珠舰是一艘专用型小轮船,但它的许多性能特别是新的船头以及更加高效的推进器都可以同样利用在大型船只上以减少耗油量与排放量。Stricter regulations on ships emissions are on their way—including, in particular, new controls for vessels in the North Sea and the Baltic, and off the coast of North America.有关部门正在制定更加严格的轮船排放标准,特别是针对北海、波罗的海和北美沿海的船只。That means shipowners who wish to ply these waters will have to stop using bunker fuel to power their vessels because burning it produces too much sulphur dioxide, nitrogen oxides and soot.这意味着船主想要在这些水域航行就必须停止使用船用燃料油因为它们在燃烧过程中会释放过多的二氧化硫、氮氧化合物和煤烟。That gives extra impetus for technology of the sort being tested in Far Solitaire.这给远航明珠舰上所试用的那种新技术的发展带来了额外的推动力。And this time no villages will have to be pillaged to pay for it.而这次,没有村庄会因此再遭受掠夺了。 /201312/270109

Not much is clear.不是非常清楚。Spending time with him has been an opportunity to relish.与他共同度过一段时光已经是一次释怀的机会。So often is the traveler experiences can seem a little package,所以旅行者的经历通常被看作是一个小包裹,but as Jaco leads me up the bare rocks to our final viewpoint,但是随着领导杰科带我跋山涉水最终来到一处景点。theres no doubting what a wild and unpackaged destination South Africa can be.毫无疑问南非就是野生及天然的理想目的地。Look at these views!看看这些美景!One of my favourite places.这是我最喜欢的地方之一。Not difficult to see why.美不胜收。Look there, you can see the camp.Yeah.看那里,你可以看到营地。You can see the was staying.你可以看到。Best of all, you can see all just voluntary area.最好的是,您可以看到所有的自愿地区。You know, its just less.你知道,这只是更少。This vast vista untouched by the modern world is the pinnacle of my journey into the wilderness.这片现代世界未曾涉足的巨大的地区就是我到野外去的旅程。201308/253632

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