为提高数据传输的可靠性，可采用“冗余校验”的方法；海明码是常_爱下问搜题

搜题请搜索小程序“爱下问搜题”

问题单项选择题

为提高数据传输的可靠性，可采用“冗余校验”的方法；海明码是常用的方法之一。在此方法中，若要求能检测出所有的双位错，并能校正单位错，则合法码字集中的码距至少为 (127) 。若原始数据的字长为5位，则采用海明码时其校验位至少为 (128) 位。

对图1-22的图(a)所示系统，仅当部件1，部件2和部件3，全部正常工作时，系统才能正常工作。图中数字为各部件的可靠性，整个系统的可靠性近似为 (129) 。如果将部件2和部件3改成由两个器件构成，如图(b)所示，只要器件a和b中有一个正常就能使部件2正常工作，只要器件c和d中有一个正常就能使部件3正常工作。图中数字是各器件的可靠性，则部件2的可靠性是 (130) ，整个系统的可靠性近似为 (131) 。

130（）

A．0.64

B．0.88

C．0.96

D．0.99

答案

参考答案：C

完形填空

A camp built by students and volunteers spreads over Southern Methodist University（SMU）. The affordable 21 are designed to be used by the poor as well as survivors of war and natural disasters.
“By the time 2020, there’s going to be about 1.7 billion people living in slums（贫民窟） so we would like to 22 change,” says Stephanie Hunt, co-founder of the Hunt Institute for Engineering and Humanities at SMU. The institute, which 23 build the village on SMU’s campus, was established to solve problem of the poor in the United States and around the world through engineering, and the free 24 .
The goal is not just to 25 lives, but to change the victims’ lives. The Institute hopes some entrepreneurs（企业家） might program and 26 some money with these ideas. One of the structures in the SMU village was built with bricks made 27 from recycled plastic bags.
They’re 28 together with heavy wires. Harvey Lacey, father of two college-aged sons, including one here at SUM, heard about this project and 29 his invention. It’s a heavy-duty, hand-crank compactor（手动压缩机）that anybody can use to form the big bricks he calls Ubuntu Blox.
“The advantages are that these 30 weigh less than two pounds. They’re very, very 31 These things can go for many generations of housing, ”says Lacey, who is 32 the design. Anybody can follow his online plans to 33 the compactor that turns plastic bags into bricks.
On this warm day, it’s 34 inside the Ubuntu Blox hut, thanks 35 to the thick plastic insulation（绝缘）. Kenyan 36 Ronald Omyonga, visiting the global village before returning to his native Africa, says his country is full of these recyclable bags. With Lacey’s design, he says that litter could be transformed into 37 housing. He dreams of other 38 too.
“Look at the Harvey Lacey hut, as a means of creating 39 ,”says Omyonga.“Leaning the environment, and turning 40 into something that can form houses, not just for the poor.”

B．competition

D．efficiently

B．contributed

D．giving away

C．photographer

问答题简答题

试述一般项目的生命周期，以及IT项目的生命周期。