SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING
LESSON TWO FUNDAMENTALS OF PAPER WRITING (Ⅱ )
The Fourth Method,Definition
A dictionary will give you two different definitions of the
word definition,(l) "a statement of what a thing is" and (2) a "a
statement or explanation of what a word or phrase means or has
meant," In the strict sense,a definition,as we shall use the word
here,is not of a thing,but of a word,or of a process.
The process of making a definition is not,however,a mere
game of words,It is clear that we cannot make a useful
definition without knowledge of the,thing” (that is,object,
event,idea,etc.) to which the word (or term) refers,And it is
equally clear that the definition of a word communicates
knowledge about the "thing" referred to,A definition does give
knowledge of "what a thing is," and equally important,may
lead the maker of definition to clarify his own thoughts on the
nature of the "thing."
SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING
In fact,a description can often serve as a definition,by
enlightening us about a thing,it enlightens us about the use of
the term that refers to the thing,For example,we find later in
this chapter a description of the mechanism used to lift liquids,
and when we have finished reading that,we know how to
define the term jet pump,But for the moment,we are not
concerned with description as a form of definition,nor
concerned with certain other kinds of definition (for instance,
what is known as recursive definition in arithmetic and
grammar),We,instead,are concerned with traditional,or
classic,definition,which goes back as far as Aristotle,Our
discussion is confined to that form.
SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING
A definition locates its subject in a class and then proceeds to
point out the characteristics that make it differ from other items
in that class and that,therefore,allow it to be assigned to a
subclass,This process is,it is clear,a special variant of the
process of classification,A definition simply sets its subject in a
limited scheme of classification.
The process of definition is,like classification,a natural way
the mind works,It is no more arbitrary than other methods of
exposition we have studied,We make definitions constantly,
and instinctively,Let us examine an example of how the
process works.
SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING
Manipulator is usually considered
as a sequence of rigid links connected
by joints with actuators,We can
construct the dynamic equations of
motion for a manipulator from the
kinematic structure and the link
parameters of the manipulator,Each
link of a manipulator has 10 link
parameters that consist of the mass,the
location of center of mass and the
inertia tensor,All the link parameters of
a manipulator are redundant in the
sense that the same dynamic equation
happens to be generated even if the link
parameters take different values.(c)
manipulator 机械手
rigid link 刚性接头
actuator 执行器
kinematic structure
运动结构
inertia tensor
惯性张量
redundant 多余的，
重复的
SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING
(c)This is caused from the fact that
two adjacent links are connected by a
joint and the relative motions of the
adjacent links are of one degree-of-
freedom,Then,what are the
parameters that are non-redundant and
enough to generate the dynamic
equations for a manipulator? This is a
very natural and fundamental question.
Such parameters will be called base
parameters.
adjacent link 相邻接头
degree-of-freedom
自由度的
base parameter 基础参数
SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING
This excerpt gives a brief account what a manipulator is,If
we chart the reasoning of the writer,we get a diagram like this,
Group Robots
Subdivision Manipulators
Components Joints and Actuators
Whenever we make a definition,we go through the same
process as the writer trying to tell what a manipulator is,We
locate the to-be-defined as a species in relation to a group that
includes several different species and then try to say what quality
or qualities distinguish the to-be-defined from the other species
in the group,The above example tells us that a manipulator is a
subdivision of the structure of a robot,This attempt to define a
manipulator is the pattern of all definitions of the classic type
and can serve most of our purposes,被定义
SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING
When defining a word we cannot define it by repeating the
word itself in the definition,If we define the word "manipulator"
by saying that it means a mechanical component that
manipulates,we have committed this error,The real question:
“What is a manipulator?” is left unanswered,The pretended
definition does not enlarge anybody's
knowledge,it merely repeats the term
to be defined,manipulators manipulate.
It is also possible to make the error of
circular definition without repeating
a word,but merely by repeating an idea,
as,“The causes of war are the several
factors that result in armed conflict.”
SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING
Thus far we have been dealing with
relatively brief definitions of the kind that
commonly appear in expository writing,We
might,for instance,begin a discussion of
drag racing by defining the term for the
uninformed reader,Sometimes,however,
particularly when we are thinking seriously
about a complicated concept,such as
democracy,we use a definition as the basis
for an entire essay,that is,we write what
may be called an extended definition.
drag racing 拉力赛
SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING
The basic problem with a word such as democracy is that no
commonly available short definition is sufficient to give us an
understanding of the full implications of the word,For suck
understanding we should have to go into the history lying behind
the word and into the complex systems of ideas involved in it,For
instance,as a basis for understanding the term democracy,we
might find ourselves not only referring to the origin of the word in
Ancient Greek,but also using the history of Athens,even
including the development of techniques and crafts that preceded
the rise of popular government,Or we might find ourselves using
the beginnings of Christianity,with its idea of the worth of the
individual human soul,in relation to the democratic impulses in
subsequent history,Contrasts and comparisons may be useful,We
would have to feel our way along,trying out different ideas to see
where they lead us,discarding some and trying again,We can use
whatever will help us,including other forms of exposition or other
modes of discourse-description,narration,or argument.
SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING
The most obvious way to organize an
extended definition is to use the standard
formula as frame,taking genus,species,
and differentiae as a basis for the
development of a discussion,Here is a
definition of what CAD/CAE systems are.
A minimal formulation using relative
coordinates is presented for variation
solid modelling,Computational methods
developed for the kinematic modelling of
mechanical systems are used to derive a
minimal problem formulation,First,the
concept of arbitrary coordinates is
introduced to reduce the dimension of the
constraint vector,Next,the variational
problem is divided into two subproblems.
coordinates 坐标系
computational method
计算方法
arbitrary coordinates
任意坐标系
constraint vector
限制矢量
SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING
(c)This is done by modelling the problem as
a graph,which is then analyzed to identify
open loops and decoupled loops,The third
methods used to reduce the size of the
variational problem is to transform the
subproblems from a Cartesian coordinate
formulation to a relative coordinate
formulation,Once identified,the often loop
subproblem is solved trivially,Finally,the
decoupled loop subproblem is solved by
optimization techniques,which minimize the
total constraint violation,Compared to the
traditional approach,the relative coordinate
method has a much smaller formulation,is
highly convergent,and is able to evaluate
under constrained geometry.
decoupled loop
分离环
Cartesian coordinate
formulation
笛卡儿坐标系
convergent 收敛的
constrained geometry
几何约束
SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING
Computer-Aided Design and Engineering systems
(CAD/CAE) use solid models for many purposes,such as
visualization of mechanical systems,and process planning.
Since the design cycle is inherently iterative,a solid model
may be modified many times during the design process.
Therefore,as a tool for conceptual design,it is important that
a solid modeler permit quick and easy changes.
Unfortunately,with current CAD tools,this is often a time-
consuming and tedious operation,Variational geometry is a
powerful tool that can reduce the time to create and modify
solid models,as well as provide a more intuitive modelling
environment,反复的
SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING
The Fifth Method,Analysis
In studying the methods of exposition thus far,we have been
often concerned with the relation of the general,of the
individual item to the class,Now,when we turn to analysis,we
treat the individual item,whatever it may be,not in relation to
something morn general or inclusive,but in relation to its own
parts.
Analysis is the method of dividing into component parts,(The
word,analysis actually means "loosening into parts,") It can be
applied to anything that can be thought of as having parts,We
can analyze an object,We can analyze an intangible,such an the
character of a person,or an idea,such as "goodness," We can
analyze an organization,such as a church or a corporation,We
can analyze a process,such as turning a workpiece,or an event,
such as the French Revolution.
SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING
You may ask how analysis differs from classification,A
class may,it is true,be said to include the items in that class,
but a class,as ordinarily conceived,has no structure in
relation to the particular items that fall within it,that is,
particular items are not parts of the class; they are example of
the class.
A thing (object,mechanism,idea,or whatever) is an
analyzable structure when its components are organized and
have a mutually supporting function in determining the nature
of the structure,A lathe is a structure,for the individual parts
supporting one another are necessary to one another and to
the machine,The human body is a structure,for the parts are
mutually necessary and necessary to the whole.
可分析的
SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING
A class does not have such characteristics,A class exists as
the idea of the qualities shared by a number of individual
items,But no one item or set of items belonging to the class is
necessary for the existence of the class,We can destroy one
individual book,or a million,and the class book,the idea of
what constitutes a book,is not impaired,But we cannot knock
many bricks from a wall or do much
cutting on a human body,Nor can
we omit an act from a play or a
logical step from an argument,For
here,too,we are dealing with
structures as common usage
recognizes,for we refer to the
structure of a play or the structure
of an argument.
SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING
An analysis cannot take place except in accordance with
the principle of the structure of the thing being analyzed,A
small child beating on an alarm clock with a heavy hammer is
not analyzing the mechanism,no matter how many things get
knocked loose,Even if he carefully takes the clock apart with
a screwdriver and not a hammer,he is still not making an
analysis--unless he grasps the principle of the relation among
the parts.
Analysis represents a rational interest of the person making
the analysis,Therefore it must be conducted by some method,
not hit-or-miss,The method used depends on the nature of the
structure under consideration.
受到考虑的
SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING
But here we must remember that the same object may,
according to the different kinds of interest brought to bear on it,
be regarded as more than one kind of structure,The botanist
would regard an apple as a botanical structure and therefore
would analyze it into stem,skin,flesh,seeds,and so forth,
whereas a chemist would regard it as a chemical structure and
would analyze it into certain elements,Or a painter would
regard it as an aesthetic structure and would analyze it into a
pattern of form and color,Each person would perform the
analysis in terms of a particular interest,and the interest
prompting the analysis would decide the kind of structure that
the object is taken to represent,The kind of structure would in
turn determine what might be regarded as the parts of the
structure.
SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING
In illustrating the fact that a particular object may be
regarded as having different kinds of structure,we have used
an example having physical existence,an apple,But what we
said may also apply to something with no physical existence,
say a short story,We may regard it as a grammatical structure,
for it is made up of words,Or we may regard it as a fictional
structure,that is,as being composed of plot,of characters,of
theme-elements that we can think of and discuss separately.
An institution may also be regarded as having different kinds
of stricture,For instance,we may regard the family as a
biological structure,or as an economic structure,or as a
moral structure,Each of these structures focuses attention on
different kinds of relationships among the members of a
family.
SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING
Analysis is the form of description achieved by
distinguishing the parts of the thing described,This kind of
description,which we shall presently contrast with ordinary
description,is called technical description.
We can contrast technical description and ordinary
description by considering the different types of occasion
from which each arises,Technical description arises from the
demand for information about the thing described,ordinary
description,from the demand for an immediate sense
impression of the thing described,The first kind of
description is expository in that it attempts to enlarge the
understanding,The second kind,ordinary description,aims to
give us an experience of the object through imagination.
SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING
Not only should we establish the relation among the parts,
but we should,to make understanding easier for our reader or
listener,settle on some single governing idea by reference to
which,for the purpose of the description,the parts can be
charted,In the following passage the comparison of the heart
to a pump gives us the basis for understanding the relation
among the parts:
SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING
The heart is a complicated mechanism.
Essentially it is a muscular pump composed
of four chambers and their incoming and
outgoing blood vessels,The action of these
chambers is coordinated and controlled by an
intricate nervous mechanism,The chambers
are paired into a right half and a left half.
The upper chamber on each side is called the
auricle; the lower,the ventricle,Each auricle
is separated from its ventricle by a muscular
valve,which permits the flow of blood
downward but prevents the leakage of blood
backward.
muscular pump
肌肉泵
chamber 心室
blood vessel 血管
auricle 心房，心耳
ventricle 下心房
SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING
The kind of analysis we have been
discussing answers the question,"How is
it put together?" A radar set is composed
of a modulator,a radio-frequency
oscillator,an antenna with scanning
mechanism,a receiver,and an indicator.
But as soon as we begin to explore the
idea of the relation among parts,we come
to another question,"How does it work?"
It is not merely the parts,but the function
of the parts in relation to a characteristic
function of the whole that now concerns
us,The explanation of how the parts of
anything relate to one another in action
we may call functional analysis.
radar set 雷达装置
modulator 调制器
radio-frequency
oscillator
电子振荡器
antenna 天线
scanning mechanism
扫描仪
indicator 指示器
SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING
The features of the one-finger testbed
we have designed,initially with the aim of
investigating,in general,tactile
exploratory paradigms,have been
described in previous paper,We
summarize here the characteristics of the
system that are relevant to the specific
"diagnostic" application considered in the
present work.
Here is an excerpt analyzing the parts
of a robot system in relation to function.
testbed 测试台
tactile exploratory
paradigm 触手
SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING
The robot system consists of three blocks:
l) a high-level "expert" system,at the top of
the control hierarchy (this "expert" decides the
overall diagnostic strategy,consisting of
sequence of tactile exploratory "subroutines"
coordinated at the intermediate control level;
the "expert" should be also capable of
processing and interpreting the data provided
by the finger sensors); 2) a middle-level block
that controls the execution of tactile
subroutines; and 3) a low-level block
comprising hardware components,a tendon
actuated,four-degree-of-freedom finger,with
sensors,motors and drivers,preprocessing
electronic units,and other sensing devices (for
instance,a TV camera).
expert system
专家系统
hierarchy 体系
subroutine 子程序
tendon 腱，钢筋束
sensor 传感器
SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING
The finger is intended to imitate functionally the index
finger of the hand,Composed of four rigid links
individually actuated by deservomotors via Bowden cables,
the finger incorporates position,velocity and torque sensors,
at each joint,as well as tactile sensors at the fingertip,The
design of the fingertip has been modified many times,At
present,the fingertip includes a foil strain gaugebased,6-
axis resultant contact force sensor at the base,and a
ferroelectrics polymer skin-like sensor at the fingertip pad.
Conceptually,the two sensors have distinct roles,in fact,
the 6-axis sensor provides the faster,linear and non-
hysteretical force feedback signal necessary for accurately,
realtime controlling contact force during manipulation,
while the skin-like sensor provides the semiquantitative
data that are usually sufficient for perceptual tasks.
有
表
头
的
铁
电
的
聚
合
物
SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING
This is a very careful analysis of a robot system,In the
first paragraph the writer explains how this system is made
up,what are the components of it,Then in the second
paragraph he farther explains how this system works.
LESSON TWO FUNDAMENTALS OF PAPER WRITING (Ⅱ )
The Fourth Method,Definition
A dictionary will give you two different definitions of the
word definition,(l) "a statement of what a thing is" and (2) a "a
statement or explanation of what a word or phrase means or has
meant," In the strict sense,a definition,as we shall use the word
here,is not of a thing,but of a word,or of a process.
The process of making a definition is not,however,a mere
game of words,It is clear that we cannot make a useful
definition without knowledge of the,thing” (that is,object,
event,idea,etc.) to which the word (or term) refers,And it is
equally clear that the definition of a word communicates
knowledge about the "thing" referred to,A definition does give
knowledge of "what a thing is," and equally important,may
lead the maker of definition to clarify his own thoughts on the
nature of the "thing."
SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING
In fact,a description can often serve as a definition,by
enlightening us about a thing,it enlightens us about the use of
the term that refers to the thing,For example,we find later in
this chapter a description of the mechanism used to lift liquids,
and when we have finished reading that,we know how to
define the term jet pump,But for the moment,we are not
concerned with description as a form of definition,nor
concerned with certain other kinds of definition (for instance,
what is known as recursive definition in arithmetic and
grammar),We,instead,are concerned with traditional,or
classic,definition,which goes back as far as Aristotle,Our
discussion is confined to that form.
SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING
A definition locates its subject in a class and then proceeds to
point out the characteristics that make it differ from other items
in that class and that,therefore,allow it to be assigned to a
subclass,This process is,it is clear,a special variant of the
process of classification,A definition simply sets its subject in a
limited scheme of classification.
The process of definition is,like classification,a natural way
the mind works,It is no more arbitrary than other methods of
exposition we have studied,We make definitions constantly,
and instinctively,Let us examine an example of how the
process works.
SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING
Manipulator is usually considered
as a sequence of rigid links connected
by joints with actuators,We can
construct the dynamic equations of
motion for a manipulator from the
kinematic structure and the link
parameters of the manipulator,Each
link of a manipulator has 10 link
parameters that consist of the mass,the
location of center of mass and the
inertia tensor,All the link parameters of
a manipulator are redundant in the
sense that the same dynamic equation
happens to be generated even if the link
parameters take different values.(c)
manipulator 机械手
rigid link 刚性接头
actuator 执行器
kinematic structure
运动结构
inertia tensor
惯性张量
redundant 多余的，
重复的
SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING
(c)This is caused from the fact that
two adjacent links are connected by a
joint and the relative motions of the
adjacent links are of one degree-of-
freedom,Then,what are the
parameters that are non-redundant and
enough to generate the dynamic
equations for a manipulator? This is a
very natural and fundamental question.
Such parameters will be called base
parameters.
adjacent link 相邻接头
degree-of-freedom
自由度的
base parameter 基础参数
SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING
This excerpt gives a brief account what a manipulator is,If
we chart the reasoning of the writer,we get a diagram like this,
Group Robots
Subdivision Manipulators
Components Joints and Actuators
Whenever we make a definition,we go through the same
process as the writer trying to tell what a manipulator is,We
locate the to-be-defined as a species in relation to a group that
includes several different species and then try to say what quality
or qualities distinguish the to-be-defined from the other species
in the group,The above example tells us that a manipulator is a
subdivision of the structure of a robot,This attempt to define a
manipulator is the pattern of all definitions of the classic type
and can serve most of our purposes,被定义
SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING
When defining a word we cannot define it by repeating the
word itself in the definition,If we define the word "manipulator"
by saying that it means a mechanical component that
manipulates,we have committed this error,The real question:
“What is a manipulator?” is left unanswered,The pretended
definition does not enlarge anybody's
knowledge,it merely repeats the term
to be defined,manipulators manipulate.
It is also possible to make the error of
circular definition without repeating
a word,but merely by repeating an idea,
as,“The causes of war are the several
factors that result in armed conflict.”
SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING
Thus far we have been dealing with
relatively brief definitions of the kind that
commonly appear in expository writing,We
might,for instance,begin a discussion of
drag racing by defining the term for the
uninformed reader,Sometimes,however,
particularly when we are thinking seriously
about a complicated concept,such as
democracy,we use a definition as the basis
for an entire essay,that is,we write what
may be called an extended definition.
drag racing 拉力赛
SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING
The basic problem with a word such as democracy is that no
commonly available short definition is sufficient to give us an
understanding of the full implications of the word,For suck
understanding we should have to go into the history lying behind
the word and into the complex systems of ideas involved in it,For
instance,as a basis for understanding the term democracy,we
might find ourselves not only referring to the origin of the word in
Ancient Greek,but also using the history of Athens,even
including the development of techniques and crafts that preceded
the rise of popular government,Or we might find ourselves using
the beginnings of Christianity,with its idea of the worth of the
individual human soul,in relation to the democratic impulses in
subsequent history,Contrasts and comparisons may be useful,We
would have to feel our way along,trying out different ideas to see
where they lead us,discarding some and trying again,We can use
whatever will help us,including other forms of exposition or other
modes of discourse-description,narration,or argument.
SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING
The most obvious way to organize an
extended definition is to use the standard
formula as frame,taking genus,species,
and differentiae as a basis for the
development of a discussion,Here is a
definition of what CAD/CAE systems are.
A minimal formulation using relative
coordinates is presented for variation
solid modelling,Computational methods
developed for the kinematic modelling of
mechanical systems are used to derive a
minimal problem formulation,First,the
concept of arbitrary coordinates is
introduced to reduce the dimension of the
constraint vector,Next,the variational
problem is divided into two subproblems.
coordinates 坐标系
computational method
计算方法
arbitrary coordinates
任意坐标系
constraint vector
限制矢量
SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING
(c)This is done by modelling the problem as
a graph,which is then analyzed to identify
open loops and decoupled loops,The third
methods used to reduce the size of the
variational problem is to transform the
subproblems from a Cartesian coordinate
formulation to a relative coordinate
formulation,Once identified,the often loop
subproblem is solved trivially,Finally,the
decoupled loop subproblem is solved by
optimization techniques,which minimize the
total constraint violation,Compared to the
traditional approach,the relative coordinate
method has a much smaller formulation,is
highly convergent,and is able to evaluate
under constrained geometry.
decoupled loop
分离环
Cartesian coordinate
formulation
笛卡儿坐标系
convergent 收敛的
constrained geometry
几何约束
SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING
Computer-Aided Design and Engineering systems
(CAD/CAE) use solid models for many purposes,such as
visualization of mechanical systems,and process planning.
Since the design cycle is inherently iterative,a solid model
may be modified many times during the design process.
Therefore,as a tool for conceptual design,it is important that
a solid modeler permit quick and easy changes.
Unfortunately,with current CAD tools,this is often a time-
consuming and tedious operation,Variational geometry is a
powerful tool that can reduce the time to create and modify
solid models,as well as provide a more intuitive modelling
environment,反复的
SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING
The Fifth Method,Analysis
In studying the methods of exposition thus far,we have been
often concerned with the relation of the general,of the
individual item to the class,Now,when we turn to analysis,we
treat the individual item,whatever it may be,not in relation to
something morn general or inclusive,but in relation to its own
parts.
Analysis is the method of dividing into component parts,(The
word,analysis actually means "loosening into parts,") It can be
applied to anything that can be thought of as having parts,We
can analyze an object,We can analyze an intangible,such an the
character of a person,or an idea,such as "goodness," We can
analyze an organization,such as a church or a corporation,We
can analyze a process,such as turning a workpiece,or an event,
such as the French Revolution.
SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING
You may ask how analysis differs from classification,A
class may,it is true,be said to include the items in that class,
but a class,as ordinarily conceived,has no structure in
relation to the particular items that fall within it,that is,
particular items are not parts of the class; they are example of
the class.
A thing (object,mechanism,idea,or whatever) is an
analyzable structure when its components are organized and
have a mutually supporting function in determining the nature
of the structure,A lathe is a structure,for the individual parts
supporting one another are necessary to one another and to
the machine,The human body is a structure,for the parts are
mutually necessary and necessary to the whole.
可分析的
SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING
A class does not have such characteristics,A class exists as
the idea of the qualities shared by a number of individual
items,But no one item or set of items belonging to the class is
necessary for the existence of the class,We can destroy one
individual book,or a million,and the class book,the idea of
what constitutes a book,is not impaired,But we cannot knock
many bricks from a wall or do much
cutting on a human body,Nor can
we omit an act from a play or a
logical step from an argument,For
here,too,we are dealing with
structures as common usage
recognizes,for we refer to the
structure of a play or the structure
of an argument.
SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING
An analysis cannot take place except in accordance with
the principle of the structure of the thing being analyzed,A
small child beating on an alarm clock with a heavy hammer is
not analyzing the mechanism,no matter how many things get
knocked loose,Even if he carefully takes the clock apart with
a screwdriver and not a hammer,he is still not making an
analysis--unless he grasps the principle of the relation among
the parts.
Analysis represents a rational interest of the person making
the analysis,Therefore it must be conducted by some method,
not hit-or-miss,The method used depends on the nature of the
structure under consideration.
受到考虑的
SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING
But here we must remember that the same object may,
according to the different kinds of interest brought to bear on it,
be regarded as more than one kind of structure,The botanist
would regard an apple as a botanical structure and therefore
would analyze it into stem,skin,flesh,seeds,and so forth,
whereas a chemist would regard it as a chemical structure and
would analyze it into certain elements,Or a painter would
regard it as an aesthetic structure and would analyze it into a
pattern of form and color,Each person would perform the
analysis in terms of a particular interest,and the interest
prompting the analysis would decide the kind of structure that
the object is taken to represent,The kind of structure would in
turn determine what might be regarded as the parts of the
structure.
SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING
In illustrating the fact that a particular object may be
regarded as having different kinds of structure,we have used
an example having physical existence,an apple,But what we
said may also apply to something with no physical existence,
say a short story,We may regard it as a grammatical structure,
for it is made up of words,Or we may regard it as a fictional
structure,that is,as being composed of plot,of characters,of
theme-elements that we can think of and discuss separately.
An institution may also be regarded as having different kinds
of stricture,For instance,we may regard the family as a
biological structure,or as an economic structure,or as a
moral structure,Each of these structures focuses attention on
different kinds of relationships among the members of a
family.
SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING
Analysis is the form of description achieved by
distinguishing the parts of the thing described,This kind of
description,which we shall presently contrast with ordinary
description,is called technical description.
We can contrast technical description and ordinary
description by considering the different types of occasion
from which each arises,Technical description arises from the
demand for information about the thing described,ordinary
description,from the demand for an immediate sense
impression of the thing described,The first kind of
description is expository in that it attempts to enlarge the
understanding,The second kind,ordinary description,aims to
give us an experience of the object through imagination.
SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING
Not only should we establish the relation among the parts,
but we should,to make understanding easier for our reader or
listener,settle on some single governing idea by reference to
which,for the purpose of the description,the parts can be
charted,In the following passage the comparison of the heart
to a pump gives us the basis for understanding the relation
among the parts:
SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING
The heart is a complicated mechanism.
Essentially it is a muscular pump composed
of four chambers and their incoming and
outgoing blood vessels,The action of these
chambers is coordinated and controlled by an
intricate nervous mechanism,The chambers
are paired into a right half and a left half.
The upper chamber on each side is called the
auricle; the lower,the ventricle,Each auricle
is separated from its ventricle by a muscular
valve,which permits the flow of blood
downward but prevents the leakage of blood
backward.
muscular pump
肌肉泵
chamber 心室
blood vessel 血管
auricle 心房，心耳
ventricle 下心房
SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING
The kind of analysis we have been
discussing answers the question,"How is
it put together?" A radar set is composed
of a modulator,a radio-frequency
oscillator,an antenna with scanning
mechanism,a receiver,and an indicator.
But as soon as we begin to explore the
idea of the relation among parts,we come
to another question,"How does it work?"
It is not merely the parts,but the function
of the parts in relation to a characteristic
function of the whole that now concerns
us,The explanation of how the parts of
anything relate to one another in action
we may call functional analysis.
radar set 雷达装置
modulator 调制器
radio-frequency
oscillator
电子振荡器
antenna 天线
scanning mechanism
扫描仪
indicator 指示器
SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING
The features of the one-finger testbed
we have designed,initially with the aim of
investigating,in general,tactile
exploratory paradigms,have been
described in previous paper,We
summarize here the characteristics of the
system that are relevant to the specific
"diagnostic" application considered in the
present work.
Here is an excerpt analyzing the parts
of a robot system in relation to function.
testbed 测试台
tactile exploratory
paradigm 触手
SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING
The robot system consists of three blocks:
l) a high-level "expert" system,at the top of
the control hierarchy (this "expert" decides the
overall diagnostic strategy,consisting of
sequence of tactile exploratory "subroutines"
coordinated at the intermediate control level;
the "expert" should be also capable of
processing and interpreting the data provided
by the finger sensors); 2) a middle-level block
that controls the execution of tactile
subroutines; and 3) a low-level block
comprising hardware components,a tendon
actuated,four-degree-of-freedom finger,with
sensors,motors and drivers,preprocessing
electronic units,and other sensing devices (for
instance,a TV camera).
expert system
专家系统
hierarchy 体系
subroutine 子程序
tendon 腱，钢筋束
sensor 传感器
SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING
The finger is intended to imitate functionally the index
finger of the hand,Composed of four rigid links
individually actuated by deservomotors via Bowden cables,
the finger incorporates position,velocity and torque sensors,
at each joint,as well as tactile sensors at the fingertip,The
design of the fingertip has been modified many times,At
present,the fingertip includes a foil strain gaugebased,6-
axis resultant contact force sensor at the base,and a
ferroelectrics polymer skin-like sensor at the fingertip pad.
Conceptually,the two sensors have distinct roles,in fact,
the 6-axis sensor provides the faster,linear and non-
hysteretical force feedback signal necessary for accurately,
realtime controlling contact force during manipulation,
while the skin-like sensor provides the semiquantitative
data that are usually sufficient for perceptual tasks.
有
表
头
的
铁
电
的
聚
合
物
SCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING
This is a very careful analysis of a robot system,In the
first paragraph the writer explains how this system is made
up,what are the components of it,Then in the second
paragraph he farther explains how this system works.
