Обучение чтению литературы на английском языке по специальности «Автономные информационные и управляющие системы» (96

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 under-

lined?

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 sys-

tem 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 свя-

зью;

–использовать открытую кольцевую архитектуру;

–большая амплитуда намагничивания;

–обеспечивать необходимую регулировку смещения напряже-

ния.

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.

_______________________

1impedance beam node – комплексное сопротивление балки.

2vibration 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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