问题 问答题

        据央视国际报道,近日(2006年3月14日摄),中国科学家率先建成了世界上第一个全超导核聚变“人造太阳”实验装置,模拟太阳产生能量。为了达到聚变所要求的温度,需要用电流产生磁场,电流的强度非常大,时间长了,线圈就要发热。从这个角度来说,装置不可能长时间运转。为了解决这个问题,人们把最新的超导技术引入到该装置中。

        虽然“人造太阳”的奇观在实验室中已经出现,但“人造太阳”所发出的电能在短时间内还不可能进入人们的家中。根据目前世界各国的研究状况,这一梦想最快有可能在50年后实现。

        “人造太阳”的实验研究具有十分重大的战略意义。在过去的100年中,人类对能源的研究和使用已从化石燃料的单一化结构,发展到以化石能源为主,核能和水能互补的多元格局。但是,石油、煤炭等化石能源不可再生,目前已经商业化的核裂变能又会产生一定的核废料,同时受到原料的限制。

        而核聚变能则被认为是无限、清洁、安全的换代新能源。据专家介绍,自然界最容易实现的聚变反应是氢的同位素——氘和氚的聚变。氘在地球的海水中藏量丰富,多达40万亿吨,如果全部用于聚变反应,释放出的能量足够人类使用几百亿年,而且反应产物是无放射性污染的氦。这就是为什么世界各国,尤其是发达国家不遗余力,竞相研究、开发核聚能的原因所在。

问:

(1)在“人造太阳”中,为什么要用到超导材料?

(2)这个装置和氢弹的原理有何相同点和不同点?

(3)核聚变的优势有哪些?(写出两点)

答案

(1)用超导材料导线不会发热,电流可以很大,设备也可以长时间运行。

(2)相同点:都是核聚变;不同点:氢弹是不可控聚变,“人造太阳”是可控聚变。

(3)清洁,无污染;原料含量丰富。

单项选择题

The first big-name hackers include Steve Wozniak, Bill Gates and Linus Torvalds, all now highly recognizable names behind many of the computer technologies used today. These early hackers had a love of technology and a compelling need to know how it all worked, and their goal was to push programs beyond what they were designed to do. Back then, the word "hacker" didn’t have the negative connotation it has today. The original hacker ethic, rooted out of simple curiosity and a need to be challenged, appears to be dead.

The objectives of early hackers are a far cry from the goals of today’s hacker. The motivation of the new breed of hackers appears not to be curiosity, or a hunger for knowledge, as it used to be. Instead, most of today’s hackers are driven by greed, power, revenge, or some other malicious intent, treating hacking as a game or sport, employing the tools that are readily available via the Internet.

The rate of security attacks is actually outpacing the growth of the Internet. This means that something besides the growth of the Internet is driving the rise in security attacks. Here are some realities you should know about: Operating systems and applications will never be secure. New vulnerabilities will be introduced into your environment every day. And even if you ever do get one operating system secure, there will be new operating systems with new vulnerabilities—phones, wireless devices, and network appliances. Employees will never keep up with security polices and awareness. It doesn’t matter how much you train and educate your employees. If your employees disregard warnings about the hazards of opening questionable email attachments, how are you going to educate them about properly configuring firewalls and intrusion detection systems for their PCs Managers have more responsibility than ever. And on top of the realities listed above, security managers are being asked to support increasing degrees of network availability and access.

There are some good security measures you can take: Employ a layer 7, full-inspection firewall. Automatically update your anti-virus at the gateway, server and client. Keep all of your systems and applications updated. Hackers commonly break into a Web site through known security holes, so make sure your servers and applications are patched and up to date. Turn off unnecessary network services. Eliminate all unneeded programs. Scan network for common backdoor services--Use intrusion detection systems, vulnerability scans, anti virus protection.

Which of the following is NOT true of security attacks()

A. Employees will keep Up with security polices and awareness if they are highly-trained

B.The rate of security attacks appears faster than the growth of the Internet

C. One’s computer system will never be secure

D. Vulnerabilities can go through phones, wireless devices, and network appliances

选择题