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5.Обучение чтению литературы на английском языке по специальности «Автономные информационные и управляющие системы» (1)

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Copyright ОАО «ЦКБ «БИБКОМ» & ООО «Aгентство Kнига-Cервис»
Московский государственный технический университет
имени Н.Э. Баумана
О.С. Никитина, О.В. Ноздрина
Обучение чтению литературы
на английском языке по специальности
«Автономные информационные
и управляющие системы»
Учебно-методическое пособие
Москва
Издательство МГТУ им. Н.Э. Баумана
2007
Copyright ОАО «ЦКБ «БИБКОМ» & ООО «Aгентство Kнига-Cервис»
УДК 802.0
ББК 81.2 Англ-923
Н624
Рецензент Т.И. Кузнецова
Никитина О.С., Ноздрина О.В.
Обучение чтению литературы на английском языке по специН624
альности «Автономные информационные и управляющие системы»: Учеб.-метод. пособие. – М.: Изд-во МГТУ им. Н.Э. Баумана,
2007. – 32 с.
Пособие, состоящее из трех разделов, содержит оригинальные тексты
на английском языке по изучаемой студентами специальности, комплексы
лексических и грамматических упражнений для развития навыков перевода научно-технической литературы, а также умения вести беседы на
профессиональные темы на английском языке.
Для студентов старших курсов, обучающихся по специальности
«Автономные информационные и управляющие системы» на факультете
«Специальное машиностроение».
УДК 802.0
ББК 81.2 Англ-923
Учебное издание
Ольга Станиславовна Никитина
Ольга Вячеславовна Ноздрина
Обучение чтению литературы
на английском языке по специальности
«Автономные информационные
и управляющие системы»
Редактор Н.М. Маслова
Корректор М.А. Василевская
Компьютерная верстка Е.В. Зимакова
Подписано в печать 02.05.2007. Формат 60х84/16. Бумага офсетная.
Печ. л. 2,0. Усл. печ. л. 1.86. Уч.-изд. л. 1,75. Тираж 100 экз.
Изд. № 148. Заказ
Издательство МГТУ им. Н.Э. Баумана
105005, Москва, 2-я Бауманская, 5
©МГТУ им. Н.Э. Баумана, 2007
Copyright ОАО «ЦКБ «БИБКОМ» & ООО «Aгентство Kнига-Cервис»
ПРЕДИСЛОВИЕ
Пособие состоит из трех разделов, подготовленных на основе
оригинальных научно-технических текстов (с очень незначительными элементами адаптации) из английских и американских периодических изданий, профиль которых соответствует специальности, изучаемой студентами.
Помимо текстов каждый раздел содержит задания, позволяющие развить навыки перевода литературы по специальности с английского языка на русский, овладеть ключевой терминологией,
связанной с предложенными в пособии темами, закрепить некоторые грамматические конструкции, характерные для научнотехнической литературы, а также развить умение вести беседы на
английском языке на темы, представляющие профессиональный
интерес.
Пособие предназначено для студентов старших курсов, обучающихся по специальности «Автономные информационные и
управляющие системы» на факультете «Специальное машиностроение».
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UNIT I
New Words and Word Combinations
adjacent a – смежный, соседний
automation system − автоматическая система
constraint v – ограничивать
customization n − обеспечение соответствия требованиям
заказчика
diagnoses problem − проблема диагностики
decompose v – paскладывать (на части)
encode v – кодировать
extend the range of smth. − расширить диапазон
exigency n − острая необходимость
fault diagnosis – диагностика неисправностей
fuzzy logic – нечеткая логика
generality n – обобщение
high-level tool – прибор высокого уровня
high-level language − язык высокого уровня
intended scope – санкционированный диапазон действия
inference n – логический вывод, следствие
inference mechanism − устройство механизма логического
вывода
inference engine – механизм логического вывода
knowledge based system (KBS) − система, основанная на
представлении знаний
kernal n – ядро
knowledge representation mechanism − механизм представления
знаний
ordering n − упорядочение
propensity n – склонность
reason v − размышлять, делать выводы
task dependent architecture − проблемно-ориентированная
архитектурная система
target application – адрес применения
toolkit n − комплект инструментальных средств разработки
программы
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undertake v – предпринимать; гарантировать
validate v – проверять достоверность; контролировать
1. Read and translate the text with a dictionary.
Text IA. The Toolkit Concept as a Task Dependent Tool
for Intelligent Automation
People are not only Homo sapience – creatures capable of forming
abstract ideas and reasoning – but also Homo Faber – makers of tools.
Apart from minor exceptions, man alone has the propensity for making
tools to aid in the pursuit of happiness and comfort. The mechanization
and the increasing rate of production moved towards the automation.
Spurred on by the Second World War, significant advances in the techniques for automatic control of machines and processes have been
made and resulted in spectacular achievements. This has led to the present so called Information Technology Revolution where the digital
computer is the most significant tool yet developed. The enormous
computational power of this machines provides significant opportunity
to develop information processing tools capable of controlling and interacting with today’s complex industrial processes. Thereby further
enhancing the automation of our production processes is carried out.
The other distinguishing feature of a man – the ability to abstract
a reason on data obtained from observations. This resulted in rapidly
developing area of Artificial Intelligence, particularly in the significant
advances of Expert Systems. They have led to the considerable interest
in developing techniques for extending the range of automation systems
to include some of the techniques which currently can be undertaken by
people.
The crucial aspect is the ability of the system to abstract the important information from the data and obtain an understanding of the situation and to decide on an action react accordingly.
Substantial world-wide interest is now developing in this area of so
called Real-Time Knowledge Systems1.
The next step in this progression – the development of tools for
automating the development of intelligent automation systems, thereby
combining the abilities of humans to reason with abstract information
with the provision of tools to enable the efficient building of complex
information progressing systems for applications in industrial automation.
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TOOLKIT is currently being validated on three important demonstrator applications relevant to industrial control diagnosis problems.
The diagnostic system using the toolkit is one of the systems validated
on demonstrator applications.
The TOOLKIT is organized as a task-dependent architecture consisting of five conceptual layers: strategic, tactical, teleological, functional and object. The tools are defined by a systematic task classification and are constructed from a set of tools components consisting of
the representation languages and their associated inference mechanisms. In addition, other tool components include the provision of truth
maintenance and causal ordering.
In developing a KBS architecture for Industrial Control Applications, the intended scope must be very carefully considered that is a
highly specific KBS would not generate a sufficient user base to justify
its development. Whereas an extremely general system would be expensive to develop and would require extensive customization for
a given application project.
The most general and also least powerful for a specific application
is a high-level language. Within this category AI languages are included, e.g. Common Lisp and Prolog. These languages must be used to
generate both the knowledge representation and the reasoning mechanism provided by Prolog is sufficient. By providing a knowledge representation mechanism and an inference engine, expert system shells
bring more power to applications but limit the scope to those applications for which the representation and inference are adequate.
More recent attempts have been focusing on developing “specialized” toolkits. These attempts are to provide a restricted set of representations and control mechanisms (tools) for a particular application domain. In addition, these toolkits may provide additional domain
dependent facilities such as graphic capabilities, interfaces, etc. It is
suggested that this reduces the scope, compared with environments, but
significantly increase the power for within the target domain.
Consistent with the general trend, it has been developed a number of
high level tools designed to solve a range of problems in Industrial
Automation applications and utilizing different types and sources of
knowledge. This approach allows the KBS designer to directly encode
his knowledge using primitives that naturally describe the problem to be
solved rather than focusing on implementation details. Compared to
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conventional KBS shells, the toolkit approach provides a much more
powerful functionality at the expense of generality. In the case of
the QUIC2 toolkit the scope of the application domain has been a priori
restricted to Industrial Automation, and hence powerful tools have been
developed for his specific but large and economically important domain.
The large spectrum and specific nature of the targeted application
domain in this project as well as the different approaches to knowledge
representation are required in modeling dynamic physical systems. This
led to the development of a specific KBS building environment according the toolkit approach. This provides a much more specialized working environment, enabling the KBS designer to build a target application by selecting appropriate toolkit modules. It also allows tools to be
included that are optimized to provide a specific functionality for a generic task, e.g. fault diagnosis.
In general, a toolkit comprises:
• A general system architecture that serves as a common reference
framework. The architecture specifies the basic function of the main
modules. These include: knowledge bases, external interfaces, working
memories, inference operators. The architecture specifies how
the modules interact and defines the flow of communication information between them.
• A set of special-purpose building tools that are tailored together
and assembled to construct a complete KBS application system. This
set will include all tools necessary for the implementation of the inference mechanisms and special facilities (e.g. explanation and justification) specified in the reference architecture.
• A set of engineering support tools to avoid the system designer in
the construction of the knowledge bases (i.e. editing, refining, the updating the represented knowledge).
• A set of specifications for the construction of external interfaces
to traditional programming environments (e.g. simulation packages,
DBMS) and towards the industrial process (data acquisition, sensors,
instrumentation actuators, etc.).
• A KBS analysis and design methodology for supporting the correct and effective use of the toolkit over the range of tasks covered by
application domain.
The paradigm of the toolkit allows high flexibility to explore different architectures for structured and efficient knowledge organization,
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and still retains the classical advantages of openness of the KBS approach. The toolkit concept embodies the proper compromise between
the contrasting exigencies of generality and specific, effective usability.
____________________
1
Real-Time Knowlege Based System – система, основанная на знаниях и работающая в режиме реального времени.
2
QUIC – четвертьдюймовый картридж.
2. Find English equivalents for the following phrases in text IA:
цепь обратной связи;
обеспечивать многократное представление и логические
выводы;
−
обеспечивать ограниченный набор представлений и управляющих механизмов для определенного домена;
−
большой спектр и специфическое происхождение домена к
адресам применения;
−
создать желаемую область применения с помощью выборки
из соответствующего модуля;
−
базовая архитектура;
−
механизм логического вывода;
−
это обеспечивает большую гибкость системы и определяет
рабочую среду;
−
обеспечивать эффективное построение систем по обработке
сложной информации;
−
раскладывать на функциональные идентификационные
блоки;
−
нужно внимательно проанализировать диапазон действия;
−
ядро тулкита;
−
системы, подходящие для наглядного показа.
−
−
3. Translate the following word combinations from English into
Russian:
−
−
−
−
−
−
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qualitative reasoning;
task specific architecture;
task dependant tools;
truth maintenance;
causal ordering;
motive power;
Copyright ОАО «ЦКБ «БИБКОМ» & ООО «Aгентство Kнига-Cервис»
−
−
−
−
−
−
−
−
−
a model-based diagnostic reasoner;
component based language;
assumption-based truth maintenance;
complex information processing system;
a knowledge representation mechanism;
expert system shell;
event graphs;
additional domain;
dependent facilities.
4. Answer the questions to text IA.
1. What spectacular achievements in mechanization have been
made after the Second World War?
2. Why is the digital computer called the most significant tool of the
Information Technology Revolution?
3. What automation systems can be currently undertaken by people?
Why?
4. What sort of tools are of the current interest for humans?
5. Сomplete the following sentences using the information from
text IA.
1.Toolkit is a _________________________ refered to a composite
software environment for supporting the design of the system.
2. The ability to reason and abstract any information _________
__________ .
3. The toolkit consists of _______________ and is organized as
_______________ .
4. A high-level language category __________ that are not specific
for a particular domain.
5. The adequacy of the inference and representation is provided by
______________ .
6. The toolkit system represents _________________ that enables
__________________________ .
6. Write a brief summary of text IA using the phrases.
1. This article is entitled ...
2. It runs about ...
3. The main points described are ...
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4. It is also mentioned ...
5. In addition ...
6. As a conclusion, it may be stressed that ...
7. Translate the sentences paying attention to the modal verbs and
the Passive constructions.
1. The distinction between ontological and empirical knowledge has
been endorsed by the industrial partners and by the experience of validation exercise.
2. The shallow system can be regarded as “brittle” as it doesn’t reason about problems even slightly out of its range of experience.
3. A new “deep” knowledge approach has been developed as a system to explain the sequence of rules used to determine an action.
4. The deep-level approach should be considered to be advantageous in deriving solutions for anticipated situations.
5. The internal states for reasoning about the behaviour of the mechanism must be defined by an internal structure of a given system.
6. There is no general agreement on how these deeper knowledge
structures should be.
7. The deep knowledge is defined to be relative, i.e. it turns to be
deep only with respect to a particular shallow description and can itself
be a shallow with respect to a deeper modal.
8. Empirical knowledge takes the word as we find it, it must be obtained from the experience based on observations.
9. Deep empirical models are called causal on which representations for the internal causal structure of a system are to be provided and
generated.
________________
Note: internal causal structure – внутренняя структура причинноследственных связей.
8. Give the reverse meaning of the following words:
weak, ordered, to construct, dependent, fault, internal, significant, flexible, to include, conventional, complex, adjacent, integrated.
9. Match English and Russian equivalents from two columns.
(1) supporting
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(a) модернизация
Copyright ОАО «ЦКБ «БИБКОМ» & ООО «Aгентство Kнига-Cервис»
(2) restricted
(3) re-engineering
(4) updating
(5) ordering
(6) time-varying
(7) enabling
(8) defined
(9) modeling
(10) based
(11) acquired
(12) associated
(b) конструирование
(c) позволяющий
(d) поддерживающий
(e) перепроектирование
(f) определяемый
(g) с переменным временем
(h) ограниченный
(i) упорядочение
(j) приобретенный
(k) обновление
(l) объединенный
10. Read and translate the text.
Text IB. Toolkit Architecture
From the beginning, one of the main motivation of the toolkit project
has been the development of a KBS architecture supporting a number of
a “high level” tools designed to solve a range of problems in Industrial
Control. This approach allows the KBS designer to directly encode his
knowledge by using primitives that naturally describe the problem to be
solved rather than focusing on implementation details.
The traditional approach to the KBS has been essentially experimental. However, the development of KBSs for complex applications,
e.g. industrial control requires a more systematic or structured approach. This is required if a software methodology for KBS is to be
developed such that systems can be built within time and cost constraints. However, a structured approach is essential to “bridging the
gap” between problem solving as expressed by the domain expert and
the knowledge representation formalisms used to encode such knowledge. What is required is a methodology for mapping problems onto
“standard” solutions. This approach relies on capability to decompose
a system, in this case a software system, into a number of weakly interconnected activities. In general, this is a difficult problem, and requires an assumption of “nearly decomposable” systems. In the domain of Industrial Control, recognition of basic problems and tasks to
be undertaken provides a mechanism for decomposition. This can take
place in both a “horizontal direction” by defining primitive elements,
based on discrimination criterion, existing at a given level, and in
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a “vertical direction” by abstraction, based on the purpose of the representations.
This results in the layered architecture, the layers corresponding to
the various conceptual distinctions (abstractions) defined in the architecture and the primitive constructs derived from an analysis of the basic tasks to be performed by the KBS.
In toolkit architecture five conceptual abstractions or layers have
been defined: Strategic, Tactical, Teleological, Functional and Object.
The Strategic and Tactical levels are composed from the toolkit by
a KBS builder for a given application. The Teleological, Functional and
Object levels exist within the QUIC Toolkit (Qualitative Industrial
Control) and represent various aggregations of software modules.
The boundary between the Teleological level and the tactical level was
determined by the analysis of the realistic level of KBS tools that could
be provided to the KBS builder.
The set of such tools needs to be general enough to support a wide
range of tasks which allow different techniques and sources of knowledge to be incorporated.
In conclusion, QUIC toolkit architecture provides the basis for
an application methodology that allows designers to identify the tools
with the aspects of a particular application. This is a substantial
improvement over former approaches.
11. Answer the questions to text IB.
1. How can the motivation for the toolkit problem be defined?
2. What approach is used for the developing of complex KBSs
nowdays?
3. What reasons for the toolkit layered architecture can be underlined?
4. What differences between conventional approaches and improved ones can be found?
12. Discuss the points of text IB:
(1) traditional approaches;
(2) improved approaches;
(3) advantages of new approaches;
(4) conceptual layers.
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13. Translate the text in the written form.
Text IC. The Structure of an Integrated Knowledge System
A layered structure in an information system makes complex system easier to manage. It is used especially in computer network protocols. The layered structure clarifies development of a system by separating portions of the Integrated Knowledge System on the developed
system on the same abstraction level to their own entitles. It also makes
the system modular which facilitates its maintenance, reusability and
portability.
In the layered structure, adjacent layers communicate with each
other through well-defined interfaces. Nonadjacent layers may not
communicate directly. The system development work can be directed to
one layer at the time while the system as a whole is manageable with
the aid of the clear interfaces.The interface between two adjacent layers
is defined as communication protocol. The protocol can be formed by
a set or predefined functions, macros, messages located on the blackboard or something else. The defined protocol has to be used in all
communication between the layers.
In the structure of the integrated system, an organization of layers
based on the abstraction is used.
The core layers of the system contain general problem solving
knowledge on some application area. The auto layers connect the core
gradually specifying to one particular operation environment. The core
manipulates information most significant for problem solving while
the outer layers collect and refine raw information for the core.
In an expert system, the knowledge included in the system is considered to be formed by:
– known facts about the current problem in the real word;
– hypotheses made during the problem solving process;
– rules describing dependencies and events between or above two.
In addition, the result of applying such structure is a knowledge system capable of utilizing existing computer programs and information
stores during its problem solving process. It must be stressed that
the structure is used in an application supporting hydrodynamic design
of ships.
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UNIT II
New Words and Word Combinations
accelerometer n − акселерометр, фазовращатель
actuate v – приводить в действие; возбуждать
amplifier n – усилитель
anchor n – точка привязки, якорь
beam n – зд. балка
bias n – смещение тока, напряжения
capacitance n – емкость
capacitor n – конденсатор
capacitive load – емкостная нагрузка
cerdip n – стеклокерамический корпус с двухрядным
расположением выводов
chopper n – оптический модулятор
conditioning n – предварительное формирование сигнала;
кондиционирование
deflect v – преломлять луч света
die-stress n − предельный удар
excitation n – зд. намагничивание током, напряжение
finger n – пальцеобразный выступ
fold v – сжимать, сворачивать
gain v − зд. усиливать
gain n − зд. усиление
interleave v – чередовать
member n – элемент
offset v – смещать
open-loop architecture – архитектура с фазовой автоподстройкой
substrate n – подложка
surface-micromachined monolithic accelerometer – микросистемный
фазовращатель
tether n – соединение, растяжка
trim v – вырезать
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2. Read and translate the text with a dictionary.
Text IIA. ADXL 150 & ADXL 250:
New Complete Low-Noise 50-g Accelerometers
The ADXL 150 and ADXL 250 represent the newest generation of
surface-micromachined accelerometers from Analog Devices. Like
the landmark ADXL 50, the new devices include both the signal conditioning circuitary and the sensor, fabricated together on a single chip –
providing acceleration measurement at a very low cost with high reliability. As with the ADXL 50, the sensor structure is a differential capacitor, but it is modified to take advantage of the experience gained
from producing millions of ADXL 50s, further advancing the state of
the art of micromachined sensor design.
Both sensors have numerous fingers along each side of the movable
center member; they constitute the center plates of a paralleled set of
differential capacitors. Pairs of fixed fingers attached to the substrate
interleave with the beam fingers to form the outer capacitor. The beam
is supported by tethers, which serve as mechanical springs. The voltage
on the moving plates is read via the electrically conductive tether anchors that support the beam.
The polysilicon support springs (tethers) are highly reliable. Many
devices have been tested by deflecting the beam with the equivalent
of > 250x the force of gravity, for 7×1010 cycles, with zero failures, as
a part of the product qualification process.
The ADXL 50s tethers extend straight out from the beam in
an `H`configuration. On the ADXL 150, however, the tethers are
folded, reducing the size of the sensor and halving the number of anchors. Since each anchor adds parasitic capacitance, the smaller number
of anchors reduces capacitive load, increasing the sensors acceleration
sensitivity. In addition, the tether geometry minimizes sensitivity to
mechanical die-stress; this allows the ADXL 150 to be packaged in
standard cerdip and surface-mount cerpak packages, which require
higher sealing temperatures than metal cans.
In addition to the sense fingers projecting from both sides of
the beam, the ADXL 150 has 12 force fingers (visible near both ends of
the beam), used for self-test actuation.
In normal operation, the fixed fingers on either side of the force fingers are at the same voltage potential as to beam and its fingers. With
no voltage between the force fingers on the beam and the fixed fingers
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on the substrate, there is no electrostatic force. However, when a digital
self-test input pin is activated, the fixed fingers on one side of the section are driven to a nonzero dc voltage applying a force to the sense
fingers, deflecting the beam. The force voltage is laser-trimmed to produce a net electrostatic force on the beam equivalent to a 10-g acceleration. This voltage will depend on the specific electrical and mechanical
characteristics of each individual device.
The self-test circuitry operates independently for normal accelerometer signal path. When signal-test is activated, the deflection it produces is measured by the device in the same way as the deflection produced by accelerating the entire device. Like an externally applied
acceleration, the deflection produced by the self-test circuitry makes
full use of the measurement circuitry of the normally functioning accelerometer. It is applied to generate an output, so it is a highly reliable
indicator of the devices able to function correctly.
2. Find English eguivalents for Russian word combinations:
– микросистемные фазовращатели;
– предварительно сформированные сигнальные цепи;
– дифференциальный конденсатор;
– новейший проект микросистемного датчика;
– многочисленные контакты, расположенные по обе стороны
элемента;
– прикрепленные к подложке;
– поддерживающие пружины;
– сокращать количество привязок;
– позволять снизить нежелательное воздействие на кристалл;
– обеспечивать силовую балансировку каналу с обратной связью;
– использовать открытую кольцевую архитектуру;
– большая амплитуда намагничивания;
– обеспечивать необходимую регулировку смещения напряжения.
3. Translate the word combinations:
– surface-micromachined monolithic accelerometers;
– modified differential capacitor;
– experience gained from producing millions of ADXLs;
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– state of the art for micromashined sensor design;
– to be read via the electrically conductive tether anchor;
– to add parasitic capacitance;
– the folded tethers;
– a digital self-test input pin;
– the normal accelerometer signal path;
– to be driven with antiphase square waves;
– a dc bias between the excitations and the beam;
– amplitude proportional to the amount of displacement;
– to provide a convenient offset adjustment;
– the open-loop architecture;
– to yield a noise density;
– movable center member.
4. Answer the questions to text IIA.
1. What components do the new accelerometers consist of?
2. What do the tethers serve?
3. What allows ADXL 150 to be packaged in standard cerdip and
surface-mount cerpack packages?
4. How is the deflection produced?
5. Insert the proper words or word combinations from the brackets.
1. The sensor used in the new devices have ______ along each
side of the movable center member.
2. The beam ______ by _____, which serve as ______ .
3. The self test produces _______ that is _____ . In the same way
as a _______ . Produced by accelerating the entire device.
4. The excitation square waves can swing _______ , including
the beam ________ at one half the supply voltage.
5. In a synchronized demodulator, that sample the output, there is
a demodulation of ___________ .
(folded tethers; deflection; to measure; finger; to be supported;
output; amplifier; to serve as a mechanical spring; biased).
6. Make up an orall summary of text IIA using the phrases.
1. This text is entitled ...
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2. It deals with ...
3. Basically ...
4. It is also mentioned that ...
5. In addition ...
6. As a conclution, it may be stressed that ...
7. Give all possible synonyms to the words:
to fabricate, to operate, latest, design, numerous, a member, via,
a failure, to increase, to allow, to use, characteristics, to indicate, a gain,
to develop.
8. Translate the sentences into Russian paying attention to the Absolute Participial Constructions and the Participles I and II.
1. The increased excitation levels employed, the chopper modulation/demodulation techniques yield a noise density of just 1mg/√Hz.
2. CMOS (complementary metal-oxide semiconductor) logic used,
the open-loop architecture simplifies signal conditioning circuitry.
3. The ADXL 250 being a single monolithic chip measuring both
the x and y coordinates of acceleration in a given plane, it is the words
first commercially available two-axis accelerometer.
4. With nothing connected to the offset adjust pin, the output voltage is unmodified.
5. With a serial or parallel D/A converter taken, complete control
can be / achieved.
6. An external operation amplifier used, the power supply voltage
increasing the sensitivity of the accelerometer.
7. An accelerometer is mounted on a PC board, the IC becoming
a part of a larger mechanical system.
8. With a three-state digital output bit and a series resistor applied, a
choice of three offset adjustment values can be achieved.
9. With zero applied acceleration, the output of the ADXL 150 is V
s/2, which is half scale of the A/D converter.
10. Each sensor receiving the clock signals via its own CMOS inverter drivers, the signals generated by the sensors are treated completely independent.
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9. Read and translate the text.
Text IIB. Circult Architecture
The fixed fingers are driven with antiphase square waves. Unlike
the ADXL 50, which uses a dc bias between the excitations and
the beam as the means of providing a force-balance feedback path,
the ADXL 150 employs an open-loop architecture. With zero average
dc voltage on the beam, the excitation square waves can swing to
the power supply rails, with the beam biased at one half of the supply
voltage. The larger amplitude of the 100-kHz excitation in the ADXL
150 results in reduced sensitivity to electronic device noise and is
a contributing factor to its improved noise performance.
With the beam centered perfectly, both sides of the differential capacitor have equal capacitance, and the ac voltage on the beam is zero.
However, if the beam is off the center due to an applied acceleration,
the differential capacitor becomes unbalanced. The beam waveform is
a square wave with amplitude proportional to the amount of displacement and hence acceleration magnitude. The phase of the beam voltage
relative to the excitation determines acceleration polarity. The beam
output is connected directly to a noninverting amplifier, which provides
buffering for the high impedance beam node1, as well as a gain
for the 100-kHz output signal.
The output is demodulated in a synchronous demodulator that samples the amplifier output after it has settled in each half of the excitation
cycle. By detecting the difference between the amplifiers output levels
for the two states, the offset voltage of the amplifier is eliminated,
much like that of a chopper stabilized amplifier. Since the demodulator
is phase synchronized with the excitation, the output signal polarity correctly indicates the direction of the applied acceleration.
The ADXL 150 has a 2-pole gain-of-3 Bessel low-pass filter on
board. These filters can be used to prevent aliasing of high-frequency
components in the demodulator output with A/D converter clock frequencies in associated data-acquisition circuitry. A second input to
the filter is connected to a resistive divider with a gain of 1 / 6, brought
out to a package pin. It provides a convenient offset adjustment point
for the accelerometer, with a net gain of +0.5 for the applied voltage.
The increased excitation levels used, along with carefully executed
chopper modulation|demodulation techniques, yield a noise density of
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just 1 mg/√ Hz, less that of the ADXL 50. The improved dynamic range
enables the ADXL 150 to be used in applications such as machine
health, vibration monitoring2, shock sensing, and instrumentation.
_______________________
1
2
impedance beam node – комплексное сопротивление балки.
vibration monitoring – диагностика машины.
10. Answer the questions to text IIB.
1. What type of architecture does the ADXL 150 employ? Why?
2. What determines the acceleration polarity?
3. Why are the low-pass filters used on board?
4. What areas enable the ADXL150 to be used and why?
5. What are the advantages of the new devices over the previous ones?
11. Complete the following sentences using the information from
texts IIA and IIB.
1. __________ results in reduced sensitivity to electronic device
noise with improved noise performance.
2. The ADXL 150 to be used in applications such as ___________ .
3. The mechanical die-stress minimizing sensitivity enables _____ .
4. The beam deflecting is used ____________________________ .
5. Buffering is known to be provided _______________________ .
6. With activated self-test input pin, ________________________ .
12. Discuss two topics.
1. The sensor operation in new devices.
2. The circuit architecture of the new accelerometer.
13. A. Translate text IIC. B. Compose five questions of your own
to it.
Text IIC. Mounting and Mechanical Considerations
of the ADXL 150 and ADXL 250
When an accelerometer is mounted on a PC board, the IC becomes
a part of a larger mechanical system. Accelerations of 50g cause the
sensor to deflect within the IC package; in addition, the PC board and
its mounting structure will deflect and deform. The motion of the board
generates a false acceleration signal, which the accelerometer can
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sense. If the resonant frequency of the supporting structure is within
the signal band or not much higher than the roll-off, the vibrations of
the PC board and its mounting system will show up in sensor output.
The best way to minimize these effects is to make the mounting
scheme as stiff as possible, thereby transmitting the system acceleration
more faithfully to the sensor and increasing the resonant frequency.
Since a PC board is much stiffer in its plane than perpendicular to its
surface, the accelerometers sensitive axis (both axes, if dual) should be
in the plane of the board. Because the ADXL 150 and ADXL 250 have
their sensitive axes in the plane of the chip, and the surface of the chip
is parallel to the base of the package, the accelerometers receive
the benefit of the HC boards stiffness when simply soldered
to thе board.
The sensitive axis were perpendicular to the plane of the chip (as is
the case for some bulk-micromachined sensors), soldering the package
to the board. Thereby it makes the measurement most susceptible to
PC-board flexibility. A right-angle mounting system could be used to
orient the sensitive axis parallel to the PC board, but the mounting system itself can deform, producing false acceleration readings.
The mounting system, and PC board stiffness, add cost to the acceleration measurement. Also the additional mass of the mounting system
lowers its resonant frequency causing larger false acceleration signals.
14. Translate texts IID and IIE in the written form without a dictoinary.
Text IID. The New Product
The TMP 17 is a monolithic temperature-to-current transducer that
provides an output current proportional to absolute temperature
(PTAT), 1 microampere per Kelvin, for temperatures from – 40 to
+105 °C (233 to 378 K). Current is independent of applied voltage, for
supplies from +4 to +30 V.
The device is inherently linear (within 0.5 °C) and stable (repeatability within 0.2 °C), and initial calibration error (25 °C) is ± 2.5 °C
max (f grade). Initial calibration error can be trimmed out by adjusting
the measuring resistance that converts current to voltage.
Because the TMP 17 is a current source, its output is immune to
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tions. The TMP 17’s small size, low cost, stability and simplicity make
it useful in applications such as cold-junction compensation, thermal
compensation of instrumentation, and over-temperature warning system
in automotive, HVAC1, and industrial temperature control.
The TMP 17 is housed in a tiny SO-8 package and available in
F and G grades.
__________________
1
HVAC (Heating Ventilation and Air Conditioning) – нагревание, вентиляция и
кондиционирование воздуха.
Text IIE. Ultrafast and Fast 14-bit A/D Converters
The AD 9243 and AD 7851converters are available today. They are
smaller, less costly and run much cooler than hybrid devices of comparable speed and resolution.
With its 3-MPS sampling rate and 40-MHz full-power signal bandwidth the AD 9243 creates a new IC speed class, especially useful in
communications and imaging, but of interest in many other fields. Its
low dissipation, single 5-V supply, differential inputs and internal reference as well as its low price and small package make possible new
applications including providing an ideal upgrade for 12-bit devices.
Besides its 333-ksps sampling rate, 20-MHz full-power signal
bandwidth and serial interface, the AD 7851 has a number of useful
features. For example, its already low maximum dissipation of <90 mW
can be further reduced to 52.5 μW max in sleep mode; with the external
clock on, dissipation in that mode is increased to only 105μW. The device contains self- and system calibration options to ensure accurate
operation over time and temperature. It powers up with a set of default
conditions and can be operated as a read-only ADC.
Both devices are available for – 40 to + 85 °C operation. The AD
7851 has a choice of 24-pin DIP1 and SOIС2.
___________________
1
2
22
DIP (Dual in line package) – корпус с двухрядным расположением выводов.
SOIC (Silicon on integral circuit) – интегральная схема в корпусе типа SO.
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UNIT III
New Words and Word Combinations
arbitrary modulation – модуляция произвольного вида
arbitrary modulation technique – произвольная техника
модуляции
bandwidth n – ширина полосы частот, ширина спектра сигнала
dispersive channel – канал с дисперсией
discard v – раскладывать
eliminate v – устранять
employ v – использовать
impairement n – неполадка; недостаток
inter-symbol interference – межсимвольное искажение внутри
сигнала
invoke v – вызывать, инициировать
map v – распределять
multiplicity n – множество
multiplexing n – частотное уплотнение
recover v – восстанавливать
robust a – надежный
sample n – выборка
scheme n – метод передачи
split v – разделять
subcarrier n – поднесущая
symbol n – условное графическое изображение символа
1. Read and translate the text with a dictonary.
Text IIIA. OFDM. General Structure
High-data-rate communications are limited not only by noise but
espeacially with increasing symbol rates and often more significantly
by the inter-symbol interference due to the memory of the dispersive
wireless communications channels.
Orthogonal Frequecy Division Multiplexing (OFDM) is well
known as a highly spectral efficient transmission scheme capable of
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dealing with severe channel impairements encountered in mobile environment.
OFDM can largely eliminate the effects of inter-symbol interference for high-speed transmission in higly dispersive channels with
a relatevely low implementation cost. It can be done by separating a
single high speed bit stream into a multiplicity of much lower speed bit
streams, each modulating a different subcarrier.
The principle of any FDM1 system is to split the information to be
trasmitted into N parallel streams, each of which modulates a carrier
using an arbitrary modulation technique.
The frequency spacing between adjacent carriers is ∆f, resulting in
a total signal bandwidth of N∆f. The resulting N modulated and multiplexed signals are transmitted over the channel, and at the reciever N parallel receiver branches recover the information. A multiplexer then recombines the N parallel information streams into a high-rate serial stream.
The digital implementation of FDM subcarrier modulators/demodulators was suggested to be based on the DFT2. The DFT is
employed for the base-band OFDM modulation/demodulation process.
The associated harmonically related frequencies can hence been used as
the set of subchannel carriers required by the OFDM system.
The serial data stream is mapped to data symbols with a symbol rate
of 1/Ts, employing a general phase and amplitude modulation scheme.
The resulting symbol stream is demultiplexed into a vector of N data
symbols So to Sn-1. The parallel data symbol stream is demultiplexed
into a vector of N data symbols So to Sn-1. The parallel data symbol
rate is 1/NTs, i.e., the parallel symbol duration is N times longer than
the serial symbol duration Ts. Hence the effects of the despersive channels which are imposed on the transmitted signal with the CIR3 become
less damaging.
Since the harmonically related and modulated individual OFDM
subcarriers can be conveniently visualized as the spectrum of the signal
to be transmitted, it is the IFFT4 – rather than the FFT5 – which is invoked, in order to transform the signal’s spectrum to the time domain
for transmission over the channel.
In the context of OFDM N frequency-domain samples produce N
time-domain samples. Both signals are assumed to be periodically repeated over an infinite time-domain and frequency-domain interval,
respectively. In order to ensure that the received time-domain OFDM
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symbol is demodulated from the channel’s steady-state – rather than
from its transient – response, each time-domain OFDM symbol is extended by the so-called cyclic extention or guard interval of Ng samples
duration, in order to overcome the inter-OFDM symbol interference
due to the channel’s memory. The signal samples recieved during
the guard interval are discarded at the receiver, and the N – sample received time-domain OFDM symbol is deemed to follow the guard interval of Ng samples duration. The demodulated OFDM symbol is then
generated from the remaining N samples upon invoking the IFFT.
OFDM is of great interest to researchers and research laboratories
all over the world. It has been accepted for the new wireless local area
network standards IEEE 802.11a, High Performance LAN type 2
(HIPERLAN/2) and MOBILE MULTIMEDIA ACCESS COMMUNICATION SYSTEMS. It is expected to be used for wireless broadband multimededia communications.
___________________________
1
FDM (Frequency Division Multiplexing) – частотное уплотнение.
DFT (Descrete Fourier Transformation) – дискретное преобразование Фурье.
3
CIR (Committed Information Rate) – согласованная скорость передачи информации.
4
IFFT (Inverse Fast Fourier Transformation) – обратное быстрое преобразование Фурье.
5
FFT (Fast Fourier Transformation) – быстрое преобразование Фурье.
2
2. Find English equivalents in text IIIA for the following Russian
words and word combinations:
– значительно;
– эффективный метод высокоспектральной передачи;
– значительные недостатки;
– соседний канал;
– межчастотный промежуток;
– ширина полосы частот;
– последовательный поток с высокими значениями;
– временная область;
– техника произвольной модуляции;
– принимать.
3. Translate from English into Russian the word combinations:
– high data rate communications;
– inter-symbol interference;
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– highly spectral efficient transmission;
– frequency spacing;
– adjacent carriers;
– arbitrary modulation teqnique;
– serial data stream;
– amplitude modulation scheme;
– time domain;
– frequency domain samples;
– cyclic extention;
– guard interval;
– wireless broadband multimedia communication.
4. Answer the questions to text IIIA.
1. What limits high data communication?
2. How can the main principles of OFDM performance be implemented?
3. Why do the effects of despersive channels imposed on the transmitted channel become less damaging?
4. What is the scheme of OFDM sample producing?
5. Why is OFDM approach of great interest all over the world
nowadays?
5. Complete the following sentences using the information from
text IIIA.
1. OFDM approach is capable to solve __________ in high-data
rate communication.
2. _________________ is the objective of the OFDM.
3. The information can be recovered by ________________ as
__________________________ .
4. Mapping of the data stream results in _____________________ .
5. In OFDM concept ________________ periodically repeated, the
recieved time domain sygnal being demodulated ____________ .
6. Write a brief summary of text IIIA using the phrases:
the article is headlined ...;
to be reviewed;
to consider briefly;
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the discussion deepens when ...;
it is noted that ...;
it is expected that…
7. Translate the sentences paying attention to the Complex Subject
and the Complex Object.
1. Multiplexing is believed to be a process of transmitting more
than one signal over a signal link, route or channel.
2. OFDM modems are assumed to employ a set of subcarriers in order
to transmit information symbols in parallel – in so called sub-channels.
3. OFDM application proved to be already adopted as the new
European digital audio broadcasting as well as for the terrestrial digital
video broadcasting systems.
4. The digital implementation of FDM subcarrier modulators\demodulators are suggested to be based on the DFT.
5. N frequency-domain samples and N time-domain samples are assumed to be periodically repeated over an infinite time-domain and frequency domain interval.
6. However we expect OFDM to be vulnarable to syncronization errors due to the narrow spacing between sub-carriers.
7. The designers wanted the system to eliminate the effects of intersymbol interference and to have a sufficiently low implementation cost
for high-speed mobile data communication.
8. OFDM proves to be sensitive to the phase noise in the oscillators.
9. We watched the expert explaining the architecture of the reciever
based on OFDM concept.
8. Translate the words paying attention to the parts of speech.
(1) module – modulated – modulate – modulation;
(2) receieve – recived – receiving – receiver;
(3) syncronize – syncronized – syncronization – syncronizated;
(4) implement – implementing – implemented – implementation;
(5) exhibit – exhibited – exhibition – exhibiting;
(6) apply – applied – application – applying;
(7) carrier – carried – carry – carring;
(8) symbol – symbolize – symbolic – symbolizing;
(9) relate – relating – related – relation;
(10) employment – employ – employed – employing.
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9. Match words and word combinations from two columns.
(1) impairement
(2) multiplicity
(3) increasing symbol rate
(4) inter-symbol interference
(5) encounter
(6) adjacent
(7) implement
(8) scheme
(9) stream
(10) map
(11) employ
(12) related
(13) sample
(14) invoke
(15) recover
(16) assume
(17) guard
(18) discard
(a) недостатки
(b) интерференция внутри
символов
(c) отбрасывать
(d) защитный
(e) признавать, допускать
(f) вызывать
(g) связанный
(h) восстанавливать
(i) поток
(j) использовать
(k) распределять
(l) осуществлять
(m) метод передачи
(n) встречаться
(o) соседний
(p) возрастающие значения
символов
(q) множество
(r) выборка
10. Read and translate the text.
Text IIIB. OFDM Implementation
In practice, the OFDM signal for the standard IEEE 802.11a is
generated as follows: in the transmitter, binary input data is incoded by
a rate 1/2 convolutional encoder1. The rate can be increased to 2/3 and
3/4. After interleaving, the binary values are converted to QUAM2 values. Four pilot values are added each 48 data values, resulting in a total
of 52 QUAM values per OFDM symbol. The symbol is modulated onto
52 subcarriers by applying the values per OFDM symbol. The symbol
is modulated onto 52 subcarries by applying the Inverse Fast Fourier
Transform (IFFT). The output is converted to serial and a cyclic extention is added to make the system robust to multipath propagation. Windowing is applied after to get a narrow output spectrum. Using an IQ
modulator3, the signal is converted to analog, which is upconverted to
the 5Ghz band, amplified, and transmitted through the antenna.
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Basically, the receiver performs the reverse operation of the transmitter, with additional training tasks. In the first step, the receiver has to
estimate frequency offset and symbol timing, using speacial training
symbols in the preamble. After removing the cyclic extention, the sygnal can be applied to a Fast Fourier Transform to recover the 52 QUAM
values of all subcarriers. The training symbols and the pilot subcarriers
are used to correct for the channel response as well as remaining phase
drift. The QUAM values are then demmapped into binary values, and
finally a Viterbi decoder decodes the information bits.
The IFFT modulates a block of input QUAM values onto a number
of subcarriers. In the receiver, the subcarriers are demodulated by
the FFT. Which is the reverse operation of the IFFT. These two operations are almost identical. In fact, the IFFT can be made using an FFT
by conjugation input and output of the FFT and deviding the output by
the FFT size. This makes it possible to use the same hardware for both
the transmitter and the receiver. Of course, this saving in complexity is
only possible when the modem does’t have to transmit and receive simultaneously, which is the case for the standard.
Orthogonal frequency division multiplexing OFDM is a special case
of multicarrier transmission, where a single data stream is transmitted
over a number of lower rate subcarriers. In 1998 OFDM was decided to
be selected as the basis for the new 5-GHz standard, targeting a range of
data stream from 6 up to 54 Mbps. This new standard is the first one to
use OFDM in packet-based communications, while the use of OFDM
until now was limited to continuous transmission systems.
________________________
1
convolutional encoder – конвольвер.
QUAM (Quadrate Amplitude Modulation) – квадратурная амплитудная модуляция.
3
(IQ) (Inphase Quadrature) modulator – фазовый квадратурный модулятор.
2
11. Answer the questions to text IIIB.
1. How is the OFDM signal generated practically?
2. What operations does the receiver perform?
3. What modulating and demodulating processes take place in
the OFDM receiver? Why?
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12. Compose a short summary of text IIIB using the words and
phrases:
to propose; to be considered in details; basically; to be of great interest.
13. Discuss three topics.
1. The main principles of OFDM performance.
2. The scheme of OFDM sample producing.
3. OFDM implementation.
14. Translate the text in the written form.
Text IIIC. The OFDM Receiver Architecture
The final architecture of the OFDM receiver exhibits robust performance in various mobile channels with high Doppler frequency. The
IF signal is sampled at 26 MHz, then digitally downconverted1 and
decimated to baseband through the I/Q demodulator. Both the pre-FFT
syncronization and post-FFT syncronization units are adopted to provide fast coarse acquisition as well as fine tracking. Channel estimation
based on the 1-D FFT/IFFT plus linear time interpolation is efficiently
implemented by reusing the FFT/IFFT engine.
The complete OFDM receiver architecture has been simulated with
the syncronization (timing, frequency, AGG) loop in dynamic and
the proposed 1-D FF/ IFFT based channel estimation and correlation
algorithm.
Various mobile channels (TV and HT) profiles have been applied to
test the robustness of the receiver. Through the simulation a frequensy
offset is assumed to be ∆f Tu = 0.1 and the transmit timing is unknown
at the receiver. The performance achived with perfect channel estimation and syncronization is also plotted as a comparison.
The performance loss of the proposed receiver is 2/2.5 dB with respect to the ideal receiver. The receiver should be notted to be robust to
Doppler frequency. The degradation from low (40Hz) to high (200 Hz)
Doppler frequency is negligible.
Such a receiver will be used to demonstrate the feasibility of highspeed mobile data access based on OFDM for the next generation cellular system.
___________________
1
30
to downconvert – преобразовывать с понижением частоты.
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СПИСОК ЛИТЕРАТУРЫ
Апполонова М.А. Specific English (грамматические трудности
перевода). – М.: Междунар. отношения, 1977.
Коваленко А.Я. Общий курс научно-технического перевода. –
Киев: Фирма «ИНКОС», 2004.
Орлов С.Б. Современный англо-русский словарь по вычислительной технике: 2-е изд., перераб. и доп. – М.: РадиоСофт, 2001.
Freeman R.L. Practical Data Communications. 2nd ed. // IEEE
Commun. 1998. Vol. 2.
Kellet J.M., Winstanley G. and Boardman J.T. A Methology for
knowledge engineering using an interactive graphical tool for knowledge modeling // Artificial Intelligence in Engineering. 1989. Vol. 4.
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Copyright ОАО «ЦКБ «БИБКОМ» & ООО «Aгентство Kнига-Cервис»
CONTENTS
Предисловие......................................................................................... 3
UNIT I
New Words and Word Combinations .................................................. 4
Text IA. The Toolkit Concept as a Task Dependent Tool
for Intelligent Automation ..................................................... 5
Text IB. Toolkit Architecture ............................................................. 11
Text IC. The Structure of an Integrated Knowledge System ............. 13
UNIT II
New Words and Word Combinations ................................................ 14
Text IIA. ADXL 250 & ADXL 250: New Complete
Low-Noise 50-g Accelerometers ...................................... 15
Text IIB. Circuit Architecture ............................................................ 19
Text IIC. Mounting and Mechanical Considerations
of the ADXL 150 and ADXL 250........................................ 20
Text IID. The New Product ................................................................ 21
Text IIE. Ultrafast and Fast 14-bit A/D Converters ........................... 22
UNIT III
New Words and Word Combinations ................................................ 23
Text IIIA. OFDM. General Structure ................................................. 23
Text IIIB. OFDM Implementation ..................................................... 28
Text IIIC. The OFDM Receiver Architecture ..................................... 30
Список литературы ........................................................................... 31
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