SCIENCE AND TECHNOLOGY ENGLIAH FOR MECHANICAL ENGINEERING LESSON TWO FUNDAMENTALS OF PAPER WRITING(I) The fourth method: Definition a dictionary will give you two different definitions of the word definition: ()"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 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 ENGLIAH FOR MECHANICAL ENGINEERING In fact. a description can often serve as a definition b y 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 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 ENGLIAH 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 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 ENGLIAH FOR MECHANICAL ENGINEERING Manipulator is usually considered as a sequence of rigid links connectedmanipulator机械手 by joints with actuators. We can‖ rigid link刚性接头 construct the dynamic equations of motion for a manipulator from theactuator执行器 kinematic structure and the link parameters of the manipulator. Each kinematic structure link of a manipulator has 10 link 运动结构 parameters that consist of the mass, the inertia tensor location of center of mass and the‖惯性张量 inertia tensor. All the link parameters of redundant多余的, a manipulator are redundant in the‖重复的 sense that the same dynamic equation happens to be generated even if the link parameters take different values. (c)
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 ENGLIAH FOR MECHANICAL ENGINEERING (c)This is caused from the fact that two adjacent links are connected by a adjacent link相邻接头 joint and the relative motions of the adjacent links are of one degree-of- degree-of-freedom freedom.Then, what are the‖自由度的 parameters that are non-redundant and enough to generate the dynamic base parameter基础参数 equations for a manipulator? This is a very natural and fundamental question Such parameters will be called base parameters
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-offreedom. 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 ENGLIAH 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 GI roup 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 nd can serve most of our purposes被定义
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 ENGLIAH 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 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 ENGLIAH 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 drag racing拉力赛 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
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 ENGLIAH 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 he word and into the complex systems of ideas invol ved in it. For instance, as a basis for understanding the term democracy,we might find oursel ves 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 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 ENGLIAH FOR MECHANICAL ENGINEERING The most obvious way to organize an extended definition is to use the standard formula as frame, taking genus, species coordinates坐标系 and differentiae as a basis for the development of a discussion. Here is a computational method definition of what CAD/CAE systems are.计算方法 A minimal formulation using relative coordinates is presented for variation arbitrary coordinates olid modelling. Computational methods‖在意坐标系 developed for the kinematic modelling of constraint vector mechanical systems are used to derive a 限制矢量 minima 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
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