2009-7-27 P,1
Unit 3
Transition to Modern Information Science
Chapter One
&Part4 Extensive Reading@ Part 1 Notes to Text
@Part5 Notes to Passage& Part 2 Word Study
@Part3 Practice on Text @Part6 Practice on Passage
2009-7-27 P,2
@ Part 1 Notes to Text
1) With the 1950‘ s came increasing awareness of the potential
of automatic devices for literature searching and information
storage and retrieval.随着二十世纪五十年代的来临，人们对用于文献资料搜索、信息储存与检索的自动装置的潜力认识日益增长。
注释,该句是一个完全倒装句。主语是 awareness；介词短语 With the
1950‘ s是状语，修饰谓语动词 came。
2) As these concepts grew in magnitude and potential,so did the
variety of information science interests,由于这些概念的大量增长，潜移默化，对信息科学研究的各种兴趣也亦如此。
注释,介词短语 in magnitude and potential作方式状语，意思是“大量地，潜移默化地”；后面的主句因为 so放在句首而倒装。 So指代前文的 grew in magnitude and potential。
Transition to Modern Information Science
2009-7-27 P,3
3) Grateful Med at the National Library of Medicine美国国家医学图书馆数据库注释,Grateful Med是对另一个 NLM（国家医学图书馆）基于网络的查询系统的链接。 Grateful Med也提供 MEDLINE（数据库）的接入，
并且还有一些其他的数据库如 AIDSLINE,HISTLINE等等。
4) Dialog and Compuserve 美国国际联机检索系统和美国最大的在线信息服务机构注释,美国 DIALOG系统是当今世界上最大的联机检索系统。现有近
500个数据库，专业内容涉及自然科学、社会科学、工程技术、人文科学、时事报道和商业经济等各个领域，是一个综合性的检索系统；
CompuServe CompuServe系统始建于 1969年，正因如此，它也有可能是第一个面向公众开放的主要 BBS系统。在 1978年就开了电子邮件广泛使用的先河,1980年引入了一个简单版本的聊天室，到上世纪八十年代早期时，这个系统开始具体成形并继而演化成以后很长一段时间里人们所见的那种样子：一个成熟可靠，范围覆盖众多城市乃至海外的在线信息服务，用户需要通过按分钟计时的拨号上网方式对其实施访问。
End
2009-7-27 P,4 End
1,transition n,过渡；演变 10,humanities n,人文学科
2,awareness n,意识,注意 11.professional n,专业的,职业的
3,automatic n,自动的,无意识的 12.curriculum n,课程
4,literature n,文献资料 13.user-oriented n,面向用户的
5,magnitude n,大小,数量 14.accessible adj,易得到的
6,batch n,批量 15.decade n,十年,十
7,mainframe n,大型机 16.community n,社区 ; 团体
8,boundary n,界限；范围 17.consequence n,影响；价值
9,fade v,渐渐消失 18.widespread n,普遍的
& Part 2 Word Study
2009-7-27 P,5
Task 1,Listening training
Dictation of some key words
Directions,You will hear some key words twice,most of which are taken from
the Word Study,Then finish the Crossword Puzzle,(See you book p,)
2,Dictation of some key expressions
Directions,You will hear some key expressions twice,most of which are
taken from this text,Then you are asked to complete the missing words.
@Part3 Practice on Text
1) ________________devices
2) ________________boundaries
3) professional______________
4) humanities and_____________
5) ________________services
6) online________________
automatic
traditional
programs
social sciences
user-oriented
databases
2009-7-27 P,6
Read and Reply
Directions:Students are required to read aloud the whole text after
the teacher,Then give short answers to the following questions:
b) When was there a move from batch processing to online
modes,from mainframe to mini and micro computers?
c) Where could user-oriented services be accessed for
the first timee by individuals?
Task 2,Read,Write and Translate
The potential of automatic devices for literature searching and
information storage and retrieval,
By the 1960s and 70s.
From their personal computers
a) What did people become more and more aware of in the 1950's?
2009-7-27 P,7
Directions:Students are required to read through the whole text again and then
tell whether the following statements true (T) or false (F).
( )1) The variety of information science interests grewgreatly and
potentially just as the concepts did.
( )2) Because traditional boundaries among disciplines never
faded,a number of information science scholars joined with
library programs,
( )3) The scholars further made themselves multidisciplinary by
incorporating disciplines in the sciences.
( )4) Individuals were able to get access to large databases from
their personal computers by the 1980's.
( )5) Numerous Special Interest Groups could hardly be seen to
respond to the changes in 1980s.
Read and Judge
End
T
F
T
T
F
2009-7-27 P,8
Directions:Read the following short passage,Complete it by filling in the missing words.
A,sheets and cards B,possible C,produce D,which E,not only
F,were G,involved H,By 1937 I,to build J,information
Otlet 1)________imagined that all the world's knowledge should be
interlinked and made available remotely to anyone,he also
proceeded 2)________a structured document collection that
3)________standardized paper 4)________filed in custom-designed
cabinets according to an ever-expanding ontology,an indexing staff
which culled 5)________worldwide from as diverse sources as
6)________,and a commercial information retrieval service
7)________answered written requests by copying relevant
information from index cards,Users of this service 8)________even
warned if their query was likely to 9)________more than 50 results
per search,10)________documentation had formally been
institutionalized,as evidenced by the founding of the American
Documentation Institute.
Read and Complete
End
E
I
G A
J
B
D
F
C
H
2009-7-27 P,9
Read and Translate
Directions:Put the following sentences into English,using the words or phrases given.
The memory of her sufferings in her childhood will never
fade from her mind.
My suitcases were examined at the Customs when I entered
the country.
End
The past 10 years saw many great changes in China.
He is proud that his wife is accessible to reason
With the beginning of the 21 century,came increasing the
awareness of the importance of the information science,
1)她永远不会忘却童年时代所受的痛苦。（ fade）
2)中国，许多变革都发生在过去的 10年。 (see)
3)他的妻子通情达理,为此他引以为豪。 (be accessible to )
4)入境时,我的提包在海关受到了检查。 (examine)
5)随着 21世纪的开始，人们越来越意识到信息技术的重要性。
（ awareness）
2009-7-27 P,10
Basical Information Theory
The main concepts of information theory can be grasped by
considering the most widespread means of human communication:
language,Two important aspects of a good language are as follows:
First,the most common words (e.g.,"a," "the," "I") should be
shorter than less common words (e.g.,"benefit," "generation,"
"mediocre"),so that sentences will not be too long,Such a tradeoff
(交易；权衡 )in word length is analogous to (类似于 )data compression (压缩 )and is the essential aspect of source coding,Second,if part of a
sentence is unheard or misheard due to noise— e.g.,a passing
car— the listener should still be able to glean(收集 )the meaning of the
underlying(隐含的 ) message,Such robustness(耐力 )is as essential for
an electronic communication system as it is for a language.
Properly building such robustness into communications is done by
channel coding,Source coding and channel coding are the
fundamental concerns of information theory.
&Part4 Extensive Reading
2009-7-27 P,11
Note that these concerns have nothing to do with the import-
ance of messages,For example,a platitude(陈词滥调 )such as
"Thank you; come again" takes about as long to say or write
as the urgent plea,"Call an ambulance!" while clearly the
latter is more important and more meaningful,Information
theory,however,does not involve message importance or
meaning,as these are matters of the quality of data rather
than the quantity of data,the latter of which is determined
solely by probabilities.
Information theory is generally considered to have been
founded in 1948 by Claude Shannon in his seminal work(奠基性著作 ),"A Mathematical Theory of Communication." The central
paradigm(范例 )of classical information theory is the engineer-
ing problem of the transmission of information over a noisy
channel,The most fundamental results of this theory are
Shannon's source coding theorem(定理,法则 ),which establishes
2009-7-27 P,12
that,on average,the number of bits needed to represent the result
of an uncertain event is given by its entropy,Shannon's noisy-
channel coding theorem states that reliable communication is
possible over noisy channels provided that the rate of communica-
tion is below a certain threshold(界限,限度 )called the channel capacity,
The channel capacity can be approached by using appropriate
encoding and decoding systems,
Information theory is closely associated with a collection of pure
and applied disciplines that have been investigated and reduced to
engineering practice under a variety of rubrics(类，目 )throughout the
world over the past half century or more,adaptive(适应的 )systems,
anticipatory (预期的 )systems,artificial intelligence,complex systems,
complexity science,cybernetics(控制论 ),informatics,machine
learning,along with systems sciences of many descriptions,
Information theory is a broad and deep mathematical theory,with
equally broad and deep applications,amongst which is the vital
field of coding theory.
2009-7-27 P,13
Coding theory is concerned with finding definite methods,
called codes,of increasing the efficiency and reducing the
net error rate of data communication over a noisy channel,
These codes can be roughly subdivided into data compres-
sion (source coding) and error-correction (channel coding)
techniques,In the latter case,it took many years to find the
methods Shannon's work proved were possible,A third class
of information theory codes are cryptographic algorithms(密码算法 ),Concepts,methods and results from coding theory and
information theory are widely used in cryptography and
cryptanalysis.
End
Claude E Shannon
(1916–2001)
2009-7-27 P,14
@Part5 Notes to Passage
1)Such a tradeoff in word length is analogous to data
compression and is the essential aspect of source coding.文字长度上的这种取舍类似数据压缩，也是信源编码的基础成分。
注释,注意 tradeoff一词在此处的含义是“取舍”或“得失”。意即：
文字的长与短。
2)Such robustness is as essential for an electronic
communication system as it is for a language,这种稳健性无论是对电子通讯系统还是对语言，都是非常重要的。
注释,robustness常被音译成“鲁棒性“，原意是“健壮和强壮”。
通常用来指系统的健壮性。它是在异常和危险情况下系统生存的关键。比如说，计算机软件在输入错误、磁盘故障、网络过载或有意攻击情况下，能否不死机、不崩溃，就是该软件的鲁棒性。鲁棒性最初是统计学中的一个专门术语,20世纪 70年代初开始在控制理论的研究中流行起来，用以表征控制系统对特性或参数摄动的不敏感性。
2009-7-27 P,15
3)Information theory,however,does not involve message
importance or meaning,as these are matters of the quality
of data rather than the quantity of data,the latter of which
is determined solely by probabilities.然而信息理论与通讯的重要性或意思无关，因为通讯的重要性和含义只不过是数据质量方面的问题而非数据的数量问题，而唯一能确定数据数量的是概率。
注释,介词 as引导的是原因状语从句，修饰全句； the latter of
which is determined solely by probabilities是非限制性定语从句,which指代 the quantity of data。
2009-7-27 P,16
4)The most fundamental results of this theory are Shannon‘ s
source coding theorem,which establishes that,on average,the
number of bits needed to represent the result of an uncertain
event is given by its entropy.这一理论最基本的成效是产生了
Shannon的信源编码定律，该定律说明，一般情况下，用来表示某一非确定事件所产生的结果所需的位数是由平均信息量给出的。
注释,克劳德 ·艾尔伍德 ·香农（ Claude Elwood Shannon,1916年 4月
30日 — 2001年 2月 26日）美国数学家、信息论的创始人。 香农于
1940年在普林斯顿高级研究所（ The Institute for Advanced Study
at Princeton）期间开始思考信息论与有效通信系统的问题。经过 8年的努力，香农在 1948年 6月和 10月在,贝尔系统技术杂志,（ Bell
System Technical Journal）上连载发表了他影像深远的论文,通讯的数学原理,。 1949年，香农又在该杂志上发表了另一着名论文,噪声下的通信,。在这两篇论文中，香农阐明了通信的基本问题，给出了通信系统的模型，提出了信息量的数学表达式，并解决了信道容量、
信源统计特性、信源编码、信道编码等一系列基本技术问题。两篇论文成为了信息论的奠基性着作。
2009-7-27 P,17
5) Shannon's noisy-channel coding theorem states that reliable
communication is possible over noisy channels provided that
the rate of communication is below a certain threshold called
the channel capacity,Shannon的噪声信道编码定律，说明可靠的通信是可以超越噪声信道的，条件是传送的速度低于信道容量的某种特定极限。
注释,该句较是复合句。 provided that意思是“假如,设若”。注意
provided 属于连词，有时用 providing。
End
2009-7-27 P,18
1.Listening Challenge
Spot Dictation
Directions,The following passage will be heard 3 times,During the second time,you
are required to put the missing words or phrases in the numbered blanks according to
what you hear,The third time is for you to check your answers,Now the passage
begins.
By the 19th Century the first signs of information science
1)______________separate and distinct from other sciences and social
sciences but in conjunction with communication and 2)______________,In
1801,Joseph Marie Jacquard 3)____________a punched card system to
control 4)_______________of the cloth weaving loom in France,It was the
first use of "memory storage of patterns" 5)_____________,As chemistry
journals emerged throughout the 6)________ and 1830s,Charles Babbage
developed his "difference engine," 7)_______________________the modern
computer,in 1822 and his "analytical engine” 8)_______________,By 1843
Richard Hoe 9)___________________the rotary press,and in 1844 Samuel
Morse sent the first public 10)________________________,By 1848 William
F,Poole begins the ‘‘ Index to Periodical Literature,’’ the first general
periodical literature index in the US.
@Part6 Practice on Passage
End
emerged as
computation
invented
operations
system
1820s
the first step towards
by 1834
developed
telegraph message
2009-7-27 P,19
End of this Unit
Unit 3
Transition to Modern Information Science
Chapter One
&Part4 Extensive Reading@ Part 1 Notes to Text
@Part5 Notes to Passage& Part 2 Word Study
@Part3 Practice on Text @Part6 Practice on Passage
2009-7-27 P,2
@ Part 1 Notes to Text
1) With the 1950‘ s came increasing awareness of the potential
of automatic devices for literature searching and information
storage and retrieval.随着二十世纪五十年代的来临，人们对用于文献资料搜索、信息储存与检索的自动装置的潜力认识日益增长。
注释,该句是一个完全倒装句。主语是 awareness；介词短语 With the
1950‘ s是状语，修饰谓语动词 came。
2) As these concepts grew in magnitude and potential,so did the
variety of information science interests,由于这些概念的大量增长，潜移默化，对信息科学研究的各种兴趣也亦如此。
注释,介词短语 in magnitude and potential作方式状语，意思是“大量地，潜移默化地”；后面的主句因为 so放在句首而倒装。 So指代前文的 grew in magnitude and potential。
Transition to Modern Information Science
2009-7-27 P,3
3) Grateful Med at the National Library of Medicine美国国家医学图书馆数据库注释,Grateful Med是对另一个 NLM（国家医学图书馆）基于网络的查询系统的链接。 Grateful Med也提供 MEDLINE（数据库）的接入，
并且还有一些其他的数据库如 AIDSLINE,HISTLINE等等。
4) Dialog and Compuserve 美国国际联机检索系统和美国最大的在线信息服务机构注释,美国 DIALOG系统是当今世界上最大的联机检索系统。现有近
500个数据库，专业内容涉及自然科学、社会科学、工程技术、人文科学、时事报道和商业经济等各个领域，是一个综合性的检索系统；
CompuServe CompuServe系统始建于 1969年，正因如此，它也有可能是第一个面向公众开放的主要 BBS系统。在 1978年就开了电子邮件广泛使用的先河,1980年引入了一个简单版本的聊天室，到上世纪八十年代早期时，这个系统开始具体成形并继而演化成以后很长一段时间里人们所见的那种样子：一个成熟可靠，范围覆盖众多城市乃至海外的在线信息服务，用户需要通过按分钟计时的拨号上网方式对其实施访问。
End
2009-7-27 P,4 End
1,transition n,过渡；演变 10,humanities n,人文学科
2,awareness n,意识,注意 11.professional n,专业的,职业的
3,automatic n,自动的,无意识的 12.curriculum n,课程
4,literature n,文献资料 13.user-oriented n,面向用户的
5,magnitude n,大小,数量 14.accessible adj,易得到的
6,batch n,批量 15.decade n,十年,十
7,mainframe n,大型机 16.community n,社区 ; 团体
8,boundary n,界限；范围 17.consequence n,影响；价值
9,fade v,渐渐消失 18.widespread n,普遍的
& Part 2 Word Study
2009-7-27 P,5
Task 1,Listening training
Dictation of some key words
Directions,You will hear some key words twice,most of which are taken from
the Word Study,Then finish the Crossword Puzzle,(See you book p,)
2,Dictation of some key expressions
Directions,You will hear some key expressions twice,most of which are
taken from this text,Then you are asked to complete the missing words.
@Part3 Practice on Text
1) ________________devices
2) ________________boundaries
3) professional______________
4) humanities and_____________
5) ________________services
6) online________________
automatic
traditional
programs
social sciences
user-oriented
databases
2009-7-27 P,6
Read and Reply
Directions:Students are required to read aloud the whole text after
the teacher,Then give short answers to the following questions:
b) When was there a move from batch processing to online
modes,from mainframe to mini and micro computers?
c) Where could user-oriented services be accessed for
the first timee by individuals?
Task 2,Read,Write and Translate
The potential of automatic devices for literature searching and
information storage and retrieval,
By the 1960s and 70s.
From their personal computers
a) What did people become more and more aware of in the 1950's?
2009-7-27 P,7
Directions:Students are required to read through the whole text again and then
tell whether the following statements true (T) or false (F).
( )1) The variety of information science interests grewgreatly and
potentially just as the concepts did.
( )2) Because traditional boundaries among disciplines never
faded,a number of information science scholars joined with
library programs,
( )3) The scholars further made themselves multidisciplinary by
incorporating disciplines in the sciences.
( )4) Individuals were able to get access to large databases from
their personal computers by the 1980's.
( )5) Numerous Special Interest Groups could hardly be seen to
respond to the changes in 1980s.
Read and Judge
End
T
F
T
T
F
2009-7-27 P,8
Directions:Read the following short passage,Complete it by filling in the missing words.
A,sheets and cards B,possible C,produce D,which E,not only
F,were G,involved H,By 1937 I,to build J,information
Otlet 1)________imagined that all the world's knowledge should be
interlinked and made available remotely to anyone,he also
proceeded 2)________a structured document collection that
3)________standardized paper 4)________filed in custom-designed
cabinets according to an ever-expanding ontology,an indexing staff
which culled 5)________worldwide from as diverse sources as
6)________,and a commercial information retrieval service
7)________answered written requests by copying relevant
information from index cards,Users of this service 8)________even
warned if their query was likely to 9)________more than 50 results
per search,10)________documentation had formally been
institutionalized,as evidenced by the founding of the American
Documentation Institute.
Read and Complete
End
E
I
G A
J
B
D
F
C
H
2009-7-27 P,9
Read and Translate
Directions:Put the following sentences into English,using the words or phrases given.
The memory of her sufferings in her childhood will never
fade from her mind.
My suitcases were examined at the Customs when I entered
the country.
End
The past 10 years saw many great changes in China.
He is proud that his wife is accessible to reason
With the beginning of the 21 century,came increasing the
awareness of the importance of the information science,
1)她永远不会忘却童年时代所受的痛苦。（ fade）
2)中国，许多变革都发生在过去的 10年。 (see)
3)他的妻子通情达理,为此他引以为豪。 (be accessible to )
4)入境时,我的提包在海关受到了检查。 (examine)
5)随着 21世纪的开始，人们越来越意识到信息技术的重要性。
（ awareness）
2009-7-27 P,10
Basical Information Theory
The main concepts of information theory can be grasped by
considering the most widespread means of human communication:
language,Two important aspects of a good language are as follows:
First,the most common words (e.g.,"a," "the," "I") should be
shorter than less common words (e.g.,"benefit," "generation,"
"mediocre"),so that sentences will not be too long,Such a tradeoff
(交易；权衡 )in word length is analogous to (类似于 )data compression (压缩 )and is the essential aspect of source coding,Second,if part of a
sentence is unheard or misheard due to noise— e.g.,a passing
car— the listener should still be able to glean(收集 )the meaning of the
underlying(隐含的 ) message,Such robustness(耐力 )is as essential for
an electronic communication system as it is for a language.
Properly building such robustness into communications is done by
channel coding,Source coding and channel coding are the
fundamental concerns of information theory.
&Part4 Extensive Reading
2009-7-27 P,11
Note that these concerns have nothing to do with the import-
ance of messages,For example,a platitude(陈词滥调 )such as
"Thank you; come again" takes about as long to say or write
as the urgent plea,"Call an ambulance!" while clearly the
latter is more important and more meaningful,Information
theory,however,does not involve message importance or
meaning,as these are matters of the quality of data rather
than the quantity of data,the latter of which is determined
solely by probabilities.
Information theory is generally considered to have been
founded in 1948 by Claude Shannon in his seminal work(奠基性著作 ),"A Mathematical Theory of Communication." The central
paradigm(范例 )of classical information theory is the engineer-
ing problem of the transmission of information over a noisy
channel,The most fundamental results of this theory are
Shannon's source coding theorem(定理,法则 ),which establishes
2009-7-27 P,12
that,on average,the number of bits needed to represent the result
of an uncertain event is given by its entropy,Shannon's noisy-
channel coding theorem states that reliable communication is
possible over noisy channels provided that the rate of communica-
tion is below a certain threshold(界限,限度 )called the channel capacity,
The channel capacity can be approached by using appropriate
encoding and decoding systems,
Information theory is closely associated with a collection of pure
and applied disciplines that have been investigated and reduced to
engineering practice under a variety of rubrics(类，目 )throughout the
world over the past half century or more,adaptive(适应的 )systems,
anticipatory (预期的 )systems,artificial intelligence,complex systems,
complexity science,cybernetics(控制论 ),informatics,machine
learning,along with systems sciences of many descriptions,
Information theory is a broad and deep mathematical theory,with
equally broad and deep applications,amongst which is the vital
field of coding theory.
2009-7-27 P,13
Coding theory is concerned with finding definite methods,
called codes,of increasing the efficiency and reducing the
net error rate of data communication over a noisy channel,
These codes can be roughly subdivided into data compres-
sion (source coding) and error-correction (channel coding)
techniques,In the latter case,it took many years to find the
methods Shannon's work proved were possible,A third class
of information theory codes are cryptographic algorithms(密码算法 ),Concepts,methods and results from coding theory and
information theory are widely used in cryptography and
cryptanalysis.
End
Claude E Shannon
(1916–2001)
2009-7-27 P,14
@Part5 Notes to Passage
1)Such a tradeoff in word length is analogous to data
compression and is the essential aspect of source coding.文字长度上的这种取舍类似数据压缩，也是信源编码的基础成分。
注释,注意 tradeoff一词在此处的含义是“取舍”或“得失”。意即：
文字的长与短。
2)Such robustness is as essential for an electronic
communication system as it is for a language,这种稳健性无论是对电子通讯系统还是对语言，都是非常重要的。
注释,robustness常被音译成“鲁棒性“，原意是“健壮和强壮”。
通常用来指系统的健壮性。它是在异常和危险情况下系统生存的关键。比如说，计算机软件在输入错误、磁盘故障、网络过载或有意攻击情况下，能否不死机、不崩溃，就是该软件的鲁棒性。鲁棒性最初是统计学中的一个专门术语,20世纪 70年代初开始在控制理论的研究中流行起来，用以表征控制系统对特性或参数摄动的不敏感性。
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3)Information theory,however,does not involve message
importance or meaning,as these are matters of the quality
of data rather than the quantity of data,the latter of which
is determined solely by probabilities.然而信息理论与通讯的重要性或意思无关，因为通讯的重要性和含义只不过是数据质量方面的问题而非数据的数量问题，而唯一能确定数据数量的是概率。
注释,介词 as引导的是原因状语从句，修饰全句； the latter of
which is determined solely by probabilities是非限制性定语从句,which指代 the quantity of data。
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4)The most fundamental results of this theory are Shannon‘ s
source coding theorem,which establishes that,on average,the
number of bits needed to represent the result of an uncertain
event is given by its entropy.这一理论最基本的成效是产生了
Shannon的信源编码定律，该定律说明，一般情况下，用来表示某一非确定事件所产生的结果所需的位数是由平均信息量给出的。
注释,克劳德 ·艾尔伍德 ·香农（ Claude Elwood Shannon,1916年 4月
30日 — 2001年 2月 26日）美国数学家、信息论的创始人。 香农于
1940年在普林斯顿高级研究所（ The Institute for Advanced Study
at Princeton）期间开始思考信息论与有效通信系统的问题。经过 8年的努力，香农在 1948年 6月和 10月在,贝尔系统技术杂志,（ Bell
System Technical Journal）上连载发表了他影像深远的论文,通讯的数学原理,。 1949年，香农又在该杂志上发表了另一着名论文,噪声下的通信,。在这两篇论文中，香农阐明了通信的基本问题，给出了通信系统的模型，提出了信息量的数学表达式，并解决了信道容量、
信源统计特性、信源编码、信道编码等一系列基本技术问题。两篇论文成为了信息论的奠基性着作。
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5) Shannon's noisy-channel coding theorem states that reliable
communication is possible over noisy channels provided that
the rate of communication is below a certain threshold called
the channel capacity,Shannon的噪声信道编码定律，说明可靠的通信是可以超越噪声信道的，条件是传送的速度低于信道容量的某种特定极限。
注释,该句较是复合句。 provided that意思是“假如,设若”。注意
provided 属于连词，有时用 providing。
End
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1.Listening Challenge
Spot Dictation
Directions,The following passage will be heard 3 times,During the second time,you
are required to put the missing words or phrases in the numbered blanks according to
what you hear,The third time is for you to check your answers,Now the passage
begins.
By the 19th Century the first signs of information science
1)______________separate and distinct from other sciences and social
sciences but in conjunction with communication and 2)______________,In
1801,Joseph Marie Jacquard 3)____________a punched card system to
control 4)_______________of the cloth weaving loom in France,It was the
first use of "memory storage of patterns" 5)_____________,As chemistry
journals emerged throughout the 6)________ and 1830s,Charles Babbage
developed his "difference engine," 7)_______________________the modern
computer,in 1822 and his "analytical engine” 8)_______________,By 1843
Richard Hoe 9)___________________the rotary press,and in 1844 Samuel
Morse sent the first public 10)________________________,By 1848 William
F,Poole begins the ‘‘ Index to Periodical Literature,’’ the first general
periodical literature index in the US.
@Part6 Practice on Passage
End
emerged as
computation
invented
operations
system
1820s
the first step towards
by 1834
developed
telegraph message
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End of this Unit
