科技英语课件 Exercises
D. attract very little attention so as to cause transmission degradation
5. The electronic equipment must operate in conjunction with other equipment without causing malfunction or degradation of any of the associated equipment. A. without making faulty operation or degeneration B. without bringing about displacement or trouble C. without inducing manufacturing problem or disadvantage D. without introducing unknown function or difficulty
6. Having defined these functions, we will proceed to show how they can be used to find new
representations for certain probability density functions typical of correlated fading applications. A. certain typical probability density functions of correlated fading applications B. some types of probability density functions for correlated applications of fading
C. some probability density functions in which applications are correlated with typical
fading
D. some probability density functions that are characteristic in correlated fading
applications
7. In a properly designed DC amplifier the effect of transistor parameter variation may be
practically eliminated if the operating point of each stage is adjusted so that it remains in the linear operation range of the transistor as temperature varies. A. it works in a region in which the transistor’s characteristics change with temperature linearly B. it performs a linear task in a range of temperature variation of the transistor C. the amplifier operates in such a way that the transistor is varied with a linear
temperature
D. the transistor stays in a state of linear operation to make the temperature vary
8. The availability of such a large collection of system performance curves in a single compilation allows the researcher or system designer to perform trade-off studies among the various communication type/fading channel/diversity combinations so as to determine the optimum choice in the face of his or her available constraints.
A. such a large number of systems with performance curves in a single book B. such a large system collected for curved performance in one book
C. such a general group of systems with forming curvatures in a single compilation D. such an extensive set of curves showing system performance within one volumeUnit 8 Exercises (1) Translate the following sentences into Chinese.
1. Early in the twentieth century, it was found that light could cause atoms to emit electrons and that, when light released an electron from an atom, the energy possessed by the electron very greatly exceeded that which the atom could, according to the electromagnetic wave theory, have received. 在二十世纪早期，人们发现光能够使原子放出电子，而且当光从原子中释放一个电子时，电子所包含的能量大大超过由电磁波理论得到的原子所接收的能量。
2. Pulse broadening determines the minimum separation between adjacent pulses, which in turn determines the maximum information-carrying capacity of the optical fiber. 脉冲的展宽决定了相邻脉冲之间的最小间隔，这一间隔进而又决定了光纤的最大信息容量。
3. If one were to transmit such information without impressing it on an optical carrier but instead on a radio frequency (RF) carrier a bit higher than the maximum rate, the transmission wavelength of the RF carrier would be centimeters or larger. 如果传输这样的信息不是将它加载到光纤上，而是加载在略高于最大速率的射频载波上，则此射频载波就会是厘米波或是波长更长一些的波。
4. The smallness of the optical wavelength, therefore, allows for the miniaturization of
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transmit and receive modules, which should allow considerable reduction in size, weight, and cost of optical communication systems with respect to microwave/radio wave counterparts.
光波波长之小使发射和接收模块得以小型化，这就使光通信系统的尺寸、重量以至价格与相应的微波、无线电波通信系统相比都大为降低。
5. Although all the advantages of coherent optical communication systems have yet to be brought to fruition, another property of optical radiation has made today’s optical communication systems not desirable for applications. 虽然相干光通信系统的所有优点还有待于落实在具体成果中，光辐射的另一性质却使目前的光通信系统不利于应用。
6. When coupled with light’s short wavelength which allows for miniature sources and detectors and micron-sized waveguides, direct detection schemes have allowed for small, lightweight, high bandwidth systems which are competitive in many areas, most notably to the present telecommunications transmission, although a myriad of other applications are continually opening up. 光的波长很小，可以使用小型的光源和检测器以及微米级的波导，于是用直接检测方案可实现在许多领域具有竞争力的小巧的宽带系统，这些领域中特别引人注目的是当前电信传输中的应用，尽管无数其他应用也在不断涌现出来。
7. As mentioned previously, these applications have tended to open up more slowly than originally predicted, as cost was really not much of a consideration in telecommunications, where equipment costs are swamped by other considerations. 如前所述，（线路）成本并非电信系统中真正重要的考虑因素，通信设备的成本主要受到其他因素的制约，因此这些应用比预料的出现得慢。
8. As wavelengths decrease to approach the size of circuit components, circuit elements are no longer lumped as such, and leads can act as reflective components and/or antennas and lumped elements as electromagnetic resonators. 随着波长减小到接近于电路元件的尺寸，电路单元就不再是集总的，导线可起到反射元件以及（或）天线的作用，集总单元则成为电磁谐振器。
(2) Choose the word or phrase that is closest in meaning to the underlined part.
1. If one were to transmit such information without impressing it on an optical carrier but instead on a radio frequency carrier, the transmission wavelength of the RF carrier would be centimeters or larger
A. without the impression that an optical carrier can replace a radio frequency carrier B. without pressing an optical carrier but instead pressing a radio frequency carrier on it C. without modulating an optical wave but instead a radio frequency wave D. this delay must indeed be no more than one internal bit
2. As mentioned previously, these applications have tended to open up more slowly than originally predicted, as cost was really not much of a consideration in telecommunications, where equipment costs are swamped by other considerations.
A. the intended applications are open and slow in the original prediction
B. there is a trend that these applications have not become available quickly enough as
expected
C. these applications are likely not to be valid gradually, but will be open as predicted D. these originally predicted applications will be open to the public slowly
3. Because of the tighter tolerances required to couple light into and between single-mode fibers, single-mode transmitters, receivers, amplifiers and other components are generally more expensive than multi-mode components
A. smaller errors in light coupling between single-mode fibers
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B. serious coupling effect between different single-mode fibers C. high difference between single-mode fibers
D. tougher requirements for feeding light into the fiber and mutual transferring between
fibers
4. The microwave band designation has never been officially sanctioned by any industrial, professional or governmental organizations. A. The design of microwave devices B. The frequency of microwave band C. The division of microwave spectrum D. The bandwidth of microwaves 5. By keeping the off state slightly below threshold, the delay between the applied electrical pulse and the resulting optical output pulse is minimized; this delay must indeed not be more than the bit interval so that the optical pulse can accurately reproduce the input signal.
A. this delay must indeed be kept within the width of one bit B. indeed, this delay must not exceed the bit of interval
C. as a matter of fact, this delay interval must be a bit less than an interval D. this delay must indeed be no more than one internal bit
6. It may be mentioned here that in optical fibers having very small core radii and small index difference between the core and cladding, it can be so arranged that only one mode of propagation exists in the fiber. A. pattern of field distribution B. method of transmission C. model of transmission line D. propagation property
7. The development of optical fiber over the last twenty years has resulted in the production of optical fiber cables that exhibit very low attenuation and transmission loss in comparison with the best copper conductors.
A. cause very small reduction in the power of signals traveling over them B. make very severe enhancement resulting in loss of transmission C. show very weak coupling and infrequent transmission failure D. attract very little attention so as to cause transmission degradation
8. Both intermodal and intramodel dispersions arise as a result of (a) waveguide effects and (b) material effects; the latter due to the finite bandwidth of the source and the fact that at different wavelengths the refractive indices are different. A. the later is caused by the fine bandwidth of the source
B. the latter effects being confined to the finite bandwidth of the source C. the material effects being a result of the restricted source bandwidth
D. both effects being the cause of the limited source bandwidthUnit 9 Exercises (1) Read the following passage and briefly answer the subsequent questions.
Now, more than ever, electrical engineers require information technology to manage their electronic design automation infrastructure. In the past, the lack of a comprehensive team-based design and process information management infrastructure for electronic design has had a negative effect on productivity. Today, information technology (IT) is used by several organizational disciplines to improve productivity.
Yet it is ironic that the electronics industry that enabled the information revolution has not taken fuller advantage of IT to improve its own productivity. The rapid growth in the use of IT — the Internet, corporate intranets, decentralized client/server computing environments — has dramatically changed the ways in which organizations manage and disseminate computer-based information. Work group interactions were once office-centered and characterized by a static, same time, same place information exchange paradigm. Today, they are increasingly taking place between geographically dispersed ―virtual offices.‖ This shift in the complexion of the workplace is compounding difficulties associated with managing information within and across organizational and geographical boundaries. Nowhere is this more prevalent than in design organizations within the electronics industry.
Over the past two decades, advances in EDA enabled electronic design teams to develop increasingly sophisticated and complex products. High-level design methods have come at the
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expense of explosive increases in the amount of design information that must be managed.
Additionally, widespread corporate initiatives to downsize and improve efficiencies, coupled with shrinking design cycles, have resulted in a demand for changes in the way design teams work. A shift toward concurrent, team-based approaches has taken place, in which large designs are hierarchically decomposed into functional blocks and developed by teams. This new way of working requires the ability to automate design process tasks and provide unobtrusive ways of allowing designers to communicate and share design information, as well as track design changes and manage the design process.
EDA vendors foster increases in designer productivity through the development of automation tools. Yet secondary importance has been placed on the capabilities needed to manage the design environment. Complicating the issue of design environment management is the wide-scale adoption of design processes which employ ―best-in-class‖ design tools from multiple EDA vendors. While EDA standards for design description and tool interoperability have eased problems with tool connectivity, a lack of standards for how electronic design information is stored, accessed, distributed, tracked, and shared makes design environment management difficult and time consuming.
The current lack of an EDA-independent design management groupware infrastructure will continue to limit the productivity gains that might otherwise have been achieved through the adoption of new design methods and tools. The inability of electronic design engineering organizations to efficiently manage and reuse design and information is adversely affecting their ability to meet time-to-market goals and corporate initiatives to improve quality. It's time for the electronics industry to fully reap the benefits of IT.
Why does the author say that it is the electronics industry that enabled the information revolution?
? How do you understand that electronics has not taken fuller advantage of IT to improve
its own productivity?
? According to the passage, what particular information techniques have significantly
influenced the organizations’ ways of managing information?
? What does it mean by ―a static, same time, same place information exchange paradigm‖? ? Give your definition to ―virtual office‖ based on the contents in this passage. ? What does EDA mean? What are its advantages?
? Why is it necessary for the design team to change their way of design? ? In which aspects the way of design has been changed? ? What in EDA have been standardized, and what have not?
? Give some of you views on the further development and improvement of EDA. (2) Choose the phrase that is closest in meaning to the underlined part.
1. When flexibility and rapid development are more important than unit costs at high volume, DSP algorithms may also be implemented using field-programmable gate arrays (FPGAs).
A. costs of large quantity of unit
B. unit that costs when tuned to high volume
C. price per unit under the condition of batch production D. costs per unit paid for a laud sound
2. Linear filters satisfy the superposition condition, i.e., if an input is a weighted linear combination of different signals, the output is an equally weighted linear combination of the corresponding output signals.
A. an input is the sum of different signals, each being multiplied by a different weight B. an input is weighted and linearly combined with different signals C. an input is linearly weighted by combining different signals D. an input is linear with a weight to combine different signals
3. Since each individual frame of a film is equivalent to a discrete sampling operation, if the rate of spokes passing a given angle is too large for a given movie frame rate, the wheels appear to be turning either backwards or at a very slow speed.
A. if the movie frame rate is too high with respect to the rate of spokes
B. if the time interval between movie frames is too short with respect to the rate of spokes C. if the spokes move across a large angle to give the rate of movie frames
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