民机通信导航与雷达(第2版) 西北工业大学出版社 下载 pdf 电子版 epub 免费 txt 2025

本书系统地介绍了现代大型飞机无线电系统的基础知识和机载设备的功能、组成与性能参数，深入浅出地说明了各种优选的机载无线电通信、导航、雷达设备的电路结构和典型功能电路的基本原理，较为全面地介绍了现代电子技术在航空无线电设备中的具体应用。本书可作为高等院校飞行器控制与信息工程专业以及民航工程专业的教材，也可供航空机务、飞行、通信、导航、空中交通管制、电子设备制造、维修等部门的人员阅读和参考。

第1章飞机无线电系统基础

1.1飞机无线电系统

1.2导航参量与位置线

习题

第2章调幅收发基础

2.1调幅发送设备基础

2.2调幅接收原理

2.3频率合成器

习题

第3章调频收发基础

3.1调频信号的产生与解调

3.2自动频率微调原理

习题

第4章电波传输与天线

4.1传输线的基础知识

4.2天线基础

4.3电波传播

习题

……

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• 作者：七月 发布时间：2021-04-19 18:01:10

  只有六个纸板内页的纸雕书。

• 作者：思维修 发布时间：2010-08-08 00:15:29

  我们意大利老师出的书~~~

• 作者：伊夏 发布时间：2022-05-26 23:15:46

  这本书其实暗藏了一个很美妙的点：它是八开的！一本八开的书，足以把任何成年人变成孩子！开本上的“魔法”带我回到差不多十岁左右的光景。我是从小不怕虫子的，因此遇到这样的书加倍欣喜，所有从小有兴趣的微观生命如今以大比例的华美图像精细呈现，搭配非常耐心幽默的解读文字，简直是一台童年时光机，让人在真实大自然的抚慰中久久不愿离去……

• 作者：豆友1485565 发布时间：2007-12-08 13:03:37

  不错～简单易懂

• 作者：lkjidm 发布时间：2019-08-03 15:37:20

  一直不喜欢渡边，也不喜欢底片，因此读的时候很是煎熬。。。

• 作者：古耐菜菜 发布时间：2018-10-30 08:25:47

  微信读书无限卡

• 从原理到实现

  作者：勇敢的萝卜 发布时间：2015-03-13 10:13:44

  当我对操作系统还是一知半解的时候看得这本书。它以unix v6的源代码为例，讲解了一个小而精的操作系统的设计。

  这本书写得言简意赅（我是指英文版的，中文版的没看过），四百多页的厚度不至于让人望而生畏。

  如果你对操作系统的原理有了一些了解，并且想进一步看看这些原理是如何在实际中运用的，那么我建议你读一读这本书，它能给你一个最直观的形象。

• Could Self-Evidence Guarantee Objectivity of Basic Values?

  作者：法妹儿 发布时间：2017-09-29 11:43:05

  Could Self-Evidence Guarantee Objectivity of Basic Values?

  In

  Natural Law and Natural Right

  , John Finnis outlines basic values and principles as contents of his natural law theory. The principal characteristic of them is so-called self-evidence, through which these basic values or principles are not subjective or arbitrary, but objective.[1] This essay would crystalize this thesis. The first part would rephrase Finnis’s arguments, and then would be a comparison between Finnis’s and Cartesian epistemology. The third part would be a short conclusion that Finnis fails because there is no mind-independent objectivity as such.

  I.

  Trying to defeat all skeptical assertions, Finnis makes a distinction between discourse about natural law and discourse about a doctrine or doctrines of natural law.[2] The theory he puts up with is about natural law, rather than doctrine or doctrines of it,[3] seeming to provide a more advanced and stable basis for natural law. This basis Finnis grounds all his theory on is that natural law is eternal and without history, but we human beings within history could grasp it. For the reason that natural law is eternal and beyond our history, it is objective; and because we could grasp it, it could have an effect on our daily life, rather than a castle in the air. This is his core thesis that the self-evidence of basic values could guarantee the objectivity.

  However, a kind of paradox is surely here: how could someone within history grasp something beyond history, and how could someone make sure that she has grasped it? Or put it in epistemological terms, how could Finnis bridge the gap between a cognitive subject who could only know something mind-dependent and something mind-independent to be known?

  Finnis’s answer is quite easy: basic values, as contents of natural law, are so self-evident that we could grasp them directly without hesitation,[4] and because of their self-evidence, basic values are indemonstrable.[5] Here we could conclude the self-evidence plays two roles in Finnis’s theory. The one is Finnis connects the knower and the known in the epistemological sense and protects the objectivity of basic values from history or subjective opinions. The other is through it, Finnis’s theory could avoid the critique from the Humean distinction between

  is

  and

  ought

  , because natural law would not come from facts, but from these indemonstrable and irrefutable basic values.[6]

  Through the analysis above, there is a strong tendency in Finnis’s theory that he tries to ground his natural law theory on a necessarily true basis (the first principle), from which he could deduce the whole system. Thus, his theory is also a variation of foundationalism in epistemology, which combining with his attempt to grasp the mind-independent reality, shares the same theoretical aim with Descartes we turn to below.

  II.

  Descartes, the founding father of modern philosophy and a notorious skeptic, is faced with the same problems as Finnis, but adapts different strategies. This part would first give an outline of Cartesian argumentation on how someone could grasp mind-independent reality and then compare his theory with Finnis’s.

  What perplexes Descartes is how we could justify what we know is what really is, not what seems to be for us.[7] The famous example is, when we see a table, how could we say it really is a table, rather than something evil deceiving us?[8] This problematic is quite similar with the paradox Finnis trying to solve as what we have argued.

  Descartes’ strategy, however, is rather different from Finnis’s. Finnis tends to adapt a kind of intuitionalism, originating from Plato’s intellectual intuition to grasp

  eidos

  . Cartesian epistemology is a kind of representationalism, in which there would be what represents and what is represented. Clear and distinct ideas would represent what really is or mind-independent reality in Descartes’ theory. His argumentation is as follows:

  (1) There are clear and distinct ideas that I know[9];

  (2) These clear and distinct ideas are necessarily true[10];

  (3) Through these clear and distinct ideas, I would get to know what really is, not what seems to be;

  (4) Why couldn’t these clear and distinct ideas deceive me?

  (5) These clear and distinct ideas come from God, which would not deceive us.[11]

  In this way, Descartes could say,

  I think, therefore I am

  , because clear and distinct ideas could not come from our sensation which could distort reality or be deceived, but come from our intellectual connection with God. The reason he develops this different strategy is, from his view, we could not trust our sensation as Aristotle has said (which is the deep root of Finnis’s theory[12]). Thus, this

  cogito

  or

  I think

  , is the supreme principle of Descartes’ theory, from which all his justification of our knowledge could be deduced.[13] In this sense, although Descartes doesn’t accept Aristotle’s justification of knowledge, he totally agrees with Aristotle’s definition of knowledge or science, which is to grasp the first principle, from which deductive inference proceeds.[14]

  Through a general outline of Cartesian epistemology, there exist two different points from Finnis’s. The one is obvious that we could not grasp mind-independent reality directly, but indirectly, namely through mediation (clear and distinct ideas). The other is implicit or presupposed by the former that only through a cognitive subject could we get to know the object. To put it in another way, the knower, as the first principle in his theory, would play a role in our cognition of the known. The first principle, in Cartesian theory, is the

  cogito

  , a thinking being; but in Finnis’s, it would be basic values without thinking (otherwise, basic values would be not so self-evident). Thus, concerning the epistemological gap between the subject and object, both Descartes’ and Finnis’s theory are variations of foundationalism, but have different even opposite attitudes towards intuition or sensation. Is Finnis right, in Descartes’ wake?

  III.

  To evaluate these two strategies, a proper way is to analyze their theoretical ambitions. As what has repeated again and again, Finnis tries to guarantee the objectivity of natural law through the self-evidence of basic values. In Descartes’ wake, the advantages and disadvantages of this strategy could be understood much more clearly. This part would describe its advantages first, and then provides a critical analysis of its disadvantages.

  By and through the self-evidence of basic values, Finnis unfolds to us someone conditioned in history could grasp natural law beyond it. Without doubt, Finnis agrees with Thomas Aquinas that while some propositions are self-evident to ‘everyone’, other proposition are self-evident only to ‘the wise’.[15] Thus, he would admit a Platonic theory that only someone by nature and nurture through could grasp

  eidos

  through intuition as what has mentioned above. This further means some principle of natural law or basic values, although they are self-evident, they may not be so self-evident to everyone. They may appear to someone, and disappear to others, but what appears and disappears would be the same. Thus, there is no need for a kind of mediation to represent what disappears to us.

  Compared with the Cartesian strategy, Finnis’ theory has at least one advantage. In Descartes’ theory, he distinguishes between what represents and what is represented. The core issue he would deal with is, how he could guarantee or justify what represents accurately corresponds to what is represented. That is the reason why Descartes introduces God into his theory: God would not deceive us and those clear and distinct ideas from it would justify this correspondence. However, in a more secular world, Descartes’ strategy would be a metaphor to tell us his theory could just assume, but not justify the correspondence between the two. Finnis’s theory, instead, intentionally or unintentionally avoids this problem because he doesn’t make the distinction as Descartes, and in fact equals what appears with what disappears.

  Nonetheless, Finnis’s theory has two fatal disadvantages. The first disadvantage, as Descartes’ famous example says, certainty, however self-evident, is quite different from knowledge, which aims at pursuing what really is.[16] The self-evidence could not function as this criterion to discern what seems to be and what really is on one hand, and Finnis could not provide other ways for us to detect what we grasp is what really is on the other hand. If he could, it would mean his basic values need demonstration or justification. What surely could be deduced is there may be a higher principle behind basic values, which would lead to infinitive regression.

  The second disadvantage follows from the first. If we accept certainty is different from what really is, then we would also accept the gap between mind-independence and mind-dependence has not been bridged through Finnis’s strategy. This deep gulf should be taken seriously for double reasons. On one hand, it means the attempt of Finnis to grasp something beyond history by someone conditioned in history would thoroughly fail, because of no criterion for Finnis to justify or demonstrate what is self-evident is what really is. On the other hand, it would stop the argumentation from self-evidence to objectivity of basic values. If we could not discern accurately what is self-evident from what really is, we have to distinguish self-evidence from objectivity, too. Besides, when we take into consideration the fact that Finnis’s theory is a variation of foundationalism, these two disadvantages would be fatal because all his system is based on the so-called self-evident, objective and indemonstrable basic values, which by and through critical analysis, may be merely self-evident, but not objective. Some scholars would oppose this argument that the definition of objectivity here is too exclusive. Objectivity could not only include what really is, but also a kind of agreement or assent within a community. This opinion is incompatible with Finnis’s theory because while he emphasizes the self-evidence of basic values that someone could grasp directly, he doesn’t assume a kind of consensus for the reason that he also admits someone could not grasp these values easily as others.

  Through the analysis above, we could clearly say these two characteristics of the beginning of Finnis’s theory, namely self-evidence (objectivity) and foundationalism, can be fatal to his whole system in a sense. The nerve here is, if Finnis only upholds the self-evidence or objectivity of basic values, and gives up foundationalism, his disability to justify the objectivity could not be so fatal as now to his theory, because a sound and reasonable theory could also be one, within which all propositions would underpin each other, constitute a coherent whole and with the development of argumentation, this coherence and explanatory power of theory would develop, too. But as Finnis combines the self-evidence with foundationalism, his standpoints would be so strong that they success once for all and fail hand in hand. Unluckily, through what has analyzed, Finnis could not justify the mind-independent objectivity of basic values as such, he has to accept his theory has a fatal shortcoming.[17]

  [1] John Finnis,

  Natural Law and Natural Rights (2nd edition)

  , Oxford University Press, 2011, pp. 64-65.

  [2] Id, p. 25.

  [3] Id.

  [4] Finnis cited Julius Stone and Aquinas to explain his idea. Id, pp. 31-32.

  [5] Id, p. 33.

  [6] In this way, Finnis rejects a classical critique that natural law is kind of theory deducing

  ought

  from

  is

  . This is a prospective defense shared by many other scholars in the field of constitutional interpretation. For example, Ronald Dworkin and James Fleming, they each advocate a kind of interpretation based on legal principles or a moral reading of constitution, claiming, say, to help a person in need is not out of the fact itself, but some moral conviction within our life. This strategy would provide judges a more flexible or pragmatic interpretation of legal texts.

  [7] Rene Descartes,

  Meditations on First Philosophy

  , Michael Moriarty trans, Oxford University Press, 2008, pp. 13-14.

  [8] Id, p. 17.

  [9] Id, p. 25, 28. Descartes distinguishes two kinds of ideas. One kind represents things outside of ourselves, but they would not necessarily do so. The other kind of ideas is derived from some notions innate within us.

  [10] In fact, clear and distinct, these two words are used by Descartes in his last Meditation. Id, p. 55.

  [11] Id, pp. 38-39.

  [12] Generally speaking, in Book VI of

  Nicomachean Ethics

  , Aristotle’s conception of science provides a basic frame of Finnis’s work. For example, they both share the view that science is aimed to grasp something eternal and necessary; they both think through sensation or experience or induction, we could also get to the eternal or necessary.

  [13] In the Second Meditation, Descartes says, “Archimedes claimed, that if only he had a point that was firm and immovable, he would move the whole earth and great things are likewise to be hoped, if I can find just one little thing that is certain and unshakeable”. See Id, p. 17.

  [14] Aristotle, Book VI, in his

  Nicomachean Ethics

  , Roger Crisp trans, Cambridge University Press, 2004, p. 104

  [15] John Finnis,

  Natural Law and Natural Rights (2nd edition)

  , Oxford University Press, 2011, p. 32.

  [16] This issue is so perplexed that at the beginning of analytic philosophy in the early twentieth century, Wittgenstein also expresses the same anxiety in his

  On Certainty

  , in which he shows to us the certainty of sensation is a kind of private, not public, knowledge.

  [17] Finnis refutes his theory has fatal shortcomings and in his

  Postscript

  of

  Natural Law and Natural Rights

  , he says, “…the book has significant weaknesses. But its main purposes and main positions remain intact”. John Finnis,

  Natural Law and Natural Rights (2nd edition)

  , Oxford University Press, 2011, p. 425.