Copyright © 2007 Pearson Education, Inc. Publishing as Pearson Addison-WesleyChapter 3More Flow of Control Slide 3- 3Copyright © 2007 Pearson Education, Inc. Publishing as Pearson Addison-WesleyOverview3.1 Using Boolean Expressions 3.2 Multiway Branches3.3 More about C++ Loop Statements3.4 Designing Loops Slide 3- 4Copyright © 2007 Pearson Education, Inc. Publishing as Pearson Addison-WesleyFlow Of ControlFlow of control refers to the order in which program statements are performedWe have seen the following ways to specify flow of controlif-else-statementswhile-statementsdo-while-statementsNew methods described in this chapter includeswitch-statementsfor-statements Copyright © 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley3.1Using Boolean Expressions Slide 3- 6Copyright © 2007 Pearson Education, Inc. Publishing as Pearson Addison-WesleyUsing Boolean ExpressionsA Boolean Expression is an expression that is either true or falseBoolean expressions are evaluated using relational operations such as= = , < , and >= which produce a boolean value and boolean operations such as&&, | |, and ! which also produce a boolean valueType bool allows declaration of variables thatcarry the value true or false Slide 3- 7Copyright © 2007 Pearson Education, Inc. Publishing as Pearson Addison-WesleyBoolean expressions are evaluated using valuesfrom the Truth Tables inFor example, if y is 8, the expression !( ( y < 3) | | ( y > 7) ) is evaluated in the following sequenceDisplay 3.1! ( false | | true )! ( true )falseEvaluating Boolean Expressions Slide 3- 8Copyright © 2007 Pearson Education, Inc. Publishing as Pearson Addison-WesleyOrder of PrecedenceIf parenthesis are omitted from boolean expressions, the default precedence of operations is:Perform ! operations firstPerform relational operations such as < nextPerform && operations nextPerform | | operations last Slide 3- 9Copyright © 2007 Pearson Education, Inc. Publishing as Pearson Addison-WesleyDisplay 3.2Precedence RulesItems in expressions are grouped by precedencerules for arithmetic and boolean operatorsOperators with higher precedence are performed firstBinary operators with equal precedence are performed left to rightUnary operators of equal precedence are performed right to left Slide 3- 10Copyright © 2007 Pearson Education, Inc. Publishing as Pearson Addison-WesleyPrecedence Rule ExampleThe expression (x+1) > 2 | | (x + 1) < -3is equivalent to ( (x + 1) > 2) | | ( ( x + 1) < -3)Because > and < have higher precedence than | | and is also equivalent to x + 1 > 2 | | x + 1 < - 3 [...]... 0) C++ uses short-circuit evaluation If the value of the leftmost sub-expression determines the final value of the expression, the rest of the expression is not evaluated Slide 3- 49 Copyright © 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley More About C++ Loop Statements A loop is a program construction that repeats a statement or sequence of statements a number of times The... Pearson Addison-Wesley Display 3.7 (1) Display 3.7 (2) Switch-statements and Menus Nested if-else statements are more versatile than a switch statement Switch-statements can make some code more clear A menu is a natural application for a switch- statement Slide 3- 11 Copyright © 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley Evaluating x + 1 > 2 | | x + 1 < - 3 Using... pieces!"; If the value of kids is zero, short-circuit evaluation prevents evaluation of (pieces / 0 >= 2) Division by zero causes a run-time error More Applications of Magnetism More Applications of Magnetism Bởi: OpenStaxCollege Mass Spectrometry The curved paths followed by charged particles in magnetic fields can be put to use A charged particle moving perpendicular to a magnetic field travels in a circular path having a radius r r= mv qB It was noted that this relationship could be used to measure the mass of charged particles such as ions A mass spectrometer is a device that measures such masses Most mass spectrometers use magnetic fields for this purpose, although some of them have extremely sophisticated designs Since there are five variables in the relationship, there are many possibilities However, if v, q, and B can be fixed, then the radius of the path r is simply proportional to the mass m of the charged particle Let us examine one such mass spectrometer that has a relatively simple design (See [link].) The process begins with an ion source, a device like an electron gun The ion source gives ions their charge, accelerates them to some velocity v, and directs a beam of them into the next stage of the spectrometer This next region is a velocity selector that only allows particles with a particular value of v to get through 1/15 More Applications of Magnetism This mass spectrometer uses a velocity selector to fix v so that the radius of the path is proportional to mass The velocity selector has both an electric field and a magnetic field, perpendicular to one another, producing forces in opposite directions on the ions Only those ions for which the forces balance travel in a straight line into the next region If the forces balance, then the electric force F = qE equals the magnetic force F = qvB, so that qE=qvB Noting that q cancels, we see that v= E B is the velocity particles must have to make it through the velocity selector, and further, that v can be selected by varying E and B In the final region, there is only a uniform magnetic field, and so the charged particles move in circular arcs with radii proportional to particle mass The paths also depend on charge q, but since q is in multiples of electron charges, it is easy to determine and to discriminate between ions in different charge states Mass spectrometry today is used extensively in chemistry and biology laboratories to identify chemical and biological substances according to their mass-to-charge ratios In medicine, mass spectrometers are used to measure the concentration of isotopes used as tracers Usually, biological molecules such as proteins are very large, so they are broken down into smaller fragments before analyzing Recently, large virus particles have been analyzed as a whole on mass spectrometers Sometimes a gas chromatograph or high- 2/15 More Applications of Magnetism performance liquid chromatograph provides an initial separation of the large molecules, which are then input into the mass spectrometer Cathode Ray Tubes—CRTs—and the Like What non-flat-screen TVs, old computer monitors, x-ray machines, and the 2-milelong Stanford Linear Accelerator have in common? All of them accelerate electrons, making them different versions of the electron gun Many of these devices use magnetic fields to steer the accelerated electrons [link] shows the construction of the type of cathode ray tube (CRT) found in some TVs, oscilloscopes, and old computer monitors Two pairs of coils are used to steer the electrons, one vertically and the other horizontally, to their desired destination The cathode ray tube (CRT) is so named because rays of electrons originate at the cathode in the electron gun Magnetic coils are used to steer the beam in many CRTs In this case, the beam is moved down Another pair of horizontal coils would steer the beam horizontally Magnetic Resonance Imaging Magnetic resonance imaging (MRI) is one of the most useful and rapidly growing medical imaging tools It non-invasively produces two-dimensional and threedimensional images of the body that provide important medical information with none of the hazards of x-rays MRI is based on an effect called nuclear magnetic resonance (NMR) in which an externally applied magnetic field interacts with the nuclei of certain atoms, particularly those of hydrogen (protons) These nuclei possess their own small magnetic fields, similar to those of electrons and the current loops discussed earlier in this chapter When placed in an external magnetic field, such nuclei experience a torque that pushes or aligns the nuclei into one of two new energy states—depending on the orientation of its spin (analogous to the N pole and S pole in a bar magnet) Transitions from the lower to higher energy state can be achieved by using an external radio frequency signal to “flip” the orientation of the small magnets (This is actually a quantum mechanical process The direction of the nuclear magnetic field is quantized as is energy in the radio waves We will return to these topics in later chapters.) The specific frequency of the radio waves that are ...169CHAPTER9Applications of the DFTThe Discrete Fourier Transform (DFT) is one of the most important tools in Digital SignalProcessing. This chapter discusses three common ways it is used. First, the DFT can calculatea signal's frequency spectrum. This is a direct examination of information encoded in thefrequency, phase, and amplitude of the component sinusoids. For example, human speech andhearing use signals with this type of encoding. Second, the DFT can find a system's frequencyresponse from the system's impulse response, and vice versa. This allows systems to be analyzedin the frequency domain, just as convolution allows systems to be analyzed in the time domain.Third, the DFT can be used as an intermediate step in more elaborate signal processingtechniques. The classic example of this is FFT convolution, an algorithm for convolving signalsthat is hundreds of times faster than conventional methods. Spectral Analysis of SignalsIt is very common for information to be encoded in the sinusoids that forma signal. This is true of naturally occurring signals, as well as those thathave been created by humans. Many things oscillate in our universe. Forexample, speech is a result of vibration of the human vocal cords; starsand planets change their brightness as they rotate on their axes and revolvearound each other; ship's propellers generate periodic displacement of thewater, and so on. The shape of the time domain waveform is not importantin these signals; the key information is in the frequency, phase andamplitude of the component sinusoids. The DFT is used to extract thisinformation. An example will show how this works. Suppose we want to investigate thesounds that travel through the ocean. To begin, a microphone is placed in thewater and the resulting electronic signal amplified to a reasonable level, say afew volts. An analog low-pass filter is then used to remove all frequenciesabove 80 hertz, so that the signal can be digitized at 160 samples per second.After acquiring and storing several thousand samples, what next? The Scientist and Engineer's Guide to Digital Signal Processing170The first thing is to simply look at the data. Figure 9-1a shows 256 samplesfrom our imaginary experiment. All that can be seen is a noisy waveform thatconveys little information to the human eye. For reasons explained shortly, thenext step is to multiply this signal by a smooth curve called a Hammingwindow, shown in (b). (Chapter 16 provides the equations for the Hammingand other windows; see Eqs. 16-1 and 16-2, and Fig. 16-2a). This results ina 256 point signal where the samples near the ends have been reduced inamplitude, as shown in (c). Taking the DFT, and converting to polar notation, results in the 129 pointfrequency spectrum in (d). Unfortunately, this also looks like a noisy mess.This is because there is not enough information in the original 256 points toobtain a well behaved curve. Using a longer DFT does nothing to help thisproblem. For example, if a 2048 point DFT is used, the frequency spectrumbecomes 1025 samples long. Even though the original 2048 points containmore information, the greater number of samples in the spectrum dilutes theinformation by the same factor. Longer DFTs provide better frequencyresolution, but the same noise level. Multi-Carrier Digital Communications Theory and Applications of OFDM Information Technology: Transmission, Processing, and Storage Series Editor: Jack Keil Wolf University of California at San Diego La Jolla, California Editorial Board: James E. Mazo Bell Laboratories, Lucent Technologies Murray Hill, New Jersey John Proakis Northeastern University Boston, Massachusetts William H. Tranter Virginia Polytechnic Institute and State University Blacksburg, Virginia Multi-Carrier Digital Communications: Theory and Applications of OFDM Ahmad R. S. Bahai and Burton R. Saltzberg Principles of Digital Transmission: With Wireless Applications Sergio Benedetto and Ezio Biglieri Simulation of Communication Systems, 2nd Edition: Methodology, Modeling, and Techniques Michel C. Jeruchim, Philip Balaban, and K. Sam Shanmugan A Continuation Order Plan is available for this series. A continuation order will bring delivery of each new volume immediately upon publication. Volumes are billed only upon actual shipment. For further information please contact the publisher. Multi-Carrier Digital Communications Theory and Applications of OFDM Ahmad R. S. Bahai and Burton R. Saltzberg Algorex, Inc. Iselin, New Jersey Kluwer Academic Publishers New York, Boston, Dordrecht, London, Moscow eBook ISBN: 0-306-46974-X Print ISBN: 0-306-46296-6 ©2002 Kluwer Academic Publishers New York, Boston, Dordrecht, London, Moscow Print ©1999 Kluwer Academic / Plenum Publishers New York All rights reserved No part of this eBook may be reproduced or transmitted in any form or by any means, electronic, mechanical, recording, or otherwise, without written consent from the Publisher Created in the United States of America Visit Kluwer Online at: http://kluweronline.com and Kluwer's eBookstore at: http://ebooks.kluweronline.com Preface Multi-carrier modulation, in particular Orthogonal Frequency Division Multiplexing (OFDM), has been successfully applied to a wide variety of digital communications applications over the past several years. Although OFDM has been chosen as the physical layer standard for a diversity of important systems, the theory, algorithms, and implementation techniques remain subjects of current interest. This is clear from the high volume of papers appearing in technical journals and conferences. This book is intended to be a concise summary of the present state of the art of the theory and practice of OFDM technology. The authors believe that the time is ripe for such a treatment. Particularly based on one of the author's long experience in development of wireless systems, and the other's in wireline systems, we have attempted to present a unified presentation of OFDM performance and implementation over a wide variety of channels. It is hoped that this will prove valuable both to developers of such systems and to researchers and graduate students involved in analysis of digital communications. In the interest of brevity, we have minimized treatment of more general communication issues. There exist many excellent texts on communication v vi Preface theory and technology. Only brief summaries of topics not specific to multi- carrier modulation are presented in this book where essential. We begin with a historical overview of multi-carrier communications, wherein its advantages for transmission over highly dispersive channels have long been recognized, particularly English morpheme system Luong Thuan & Kim Phuong Acknowledgment Firstly, we are deeply grateful to Ms Huyen Nguyen Thi Thanh, my supervisor for her valuable instructions, corrections and assistance during the implementation process of our graduation thesis. Secondly, we would like to give our special thanks to all lecturers and staff from the Foreign Language Faculty, English Department of Phuong Dong University for giving us opportunities and encouragement to complete our study. Finally, we also would like to express our sincere thanks to TA vu Son Tung for his support during our process to complete this essay. Group: Luong Thi Thuan Ha Kim Phuong 1 English morpheme system Luong Thuan & Kim Phuong OUTLINE Part I: Introduction. 1. Rationale (reasons of the study) .3 2. Aims of the study .3 3. Scope of the study 3 4. Methods of the study 4 Part II: Development. Chapter 1: Theoretical background. I. An overview of English morpheme I.1. Definition of Morpheme .5 I.2. Type of morpheme .6 II. An overview of Vietnamese morpheme II.1. Definition of Vietnamese morpheme .9 II.2. Derivational morphology: word formation 9 Chapter 2: Comparison with Vietnamese morphology. 1. The similarities 11 2. The difference .13 3. Some suggestion .15 Part III: Conclusion .18 Exercises 19 References .23 2 English morpheme system Luong Thuan & Kim Phuong Part I: Introduction 1. The rationale “Language is the most important social communication among countries and people in the world”, said V.I Lenin. As the world changes and develops, the global integration becomes the trend in all over the world. All countries, including Viet Nam have been cooperated with each other in many aspects of society in order to enhance development of economy. It designated international communication as an important part of all sectors. English is considered as the international language which is widely used all over the world. However, each language as well as English has its own typical features which make difficulties for learners. To learn English well, first of all, we should understand deeply about its morpheme system. Living in a community, human beings need a tool to communicate with each other, and to carry on human and social affairs. They, therefore, arbitrarily named the things and occurrences around making use of vocal sounds for the purpose of communication. After that they showed the vocal sounds and sets of vocal sounds in written signals. Because of these reasons, we decided to choose the topic “English morpheme system and some applications of learning morpheme in establishing words”. 2. Aims of the study We hope that our study is useful for English learners, for those who want to consolidate their knowledge about ... right-out of page, left-into page What are the directions of the fields in the center of the loop and coils shown in [link]? 7/15 More Applications of Magnetism What are the directions of the currents... same potential 10/15 More Applications of Magnetism Integrated Concepts Find the radius of curvature of the path of a 25.0-MeV proton moving perpendicularly to the 1.20-T field of a cyclotron 60.2... consider are the types of ions, the velocities they can be given before entering the magnetic field, and a reasonable value for the radius of curvature of 14/15 More Applications of Magnetism the paths