Grammar: The Infinitive. Split Infinitives

Word List:

1. features	особенности, черты, свойства
2. actuator	пускатель, исполнительный механизм регулятора, силовой привод
3. web pages	электронные страницы, сайты
4. power unit	блок питания
5. output	выходные данные, мощность, производительность, отдача, продукция
6. Hydraulic Power Unit HPU	гидравлический энергоблок/ силовой агрегат
7. symbolic representation	схемы, чертежи

8. dialog box	монитор в компьютере
9. weighting sum	сумма с учетом весовых коэффициентов, т.е. с учетом значимости каждого параметра
10. pressure settings	установки (указания), обеспечивающие давление
11. load interaction	влияние нагрузки
12. supply and return lines	вводящие и выводящие (исходящие) линии
13. ballpark figures	близкие к реальным значениям цифры
14. to size the prime mover	оценить размеры первичного двигателя

Expert Systems. Other Useful Features

Output from the prototype pays special attention to the circuit presentation, which includes a symbolic representation, description in text, and an explanation of the choice for a specific configuration. For an actuation circuit, this choice is determined based on corresponding load attributes. For the HPU, the choice is made according to pressure and flow demands of all actuators.

Another convenient feature that enhances the design process is the ability to easily change the HPU specifications or configuration. This is done by suggesting that a user verifies alternative HPUs. These alternatives are described in web pages using graphics and notes on cost, safety, and applicability.

After analyzing the design alternatives, a user can choose to accept or reject design options. Once a selection is made, the prototype updates all system diagrams and incorporates the user’s new choice of HPU. However, this process is reversible; the user can replace the power unit or reselect the previous one. This feature shortens the time to configure diagrams and redefine component lists and gives users freedom of choice to play
“what if.”

The program provides multiple choices for actuation circuits, and the user selects the most appropriate for the specific application. To do this, the user defines and ranks a set of application parameters. This process is carried out through a dialog box where the user prioritizes five criteria. Once priorities are established, the prototype performs a weighting sum and establishes all ranking systems as guidelines for the user. This information is also accessible as web pages.

Another important feature is the ability to automatically size the circuits. Once the user defines the numerical parameters for all loads, the program guides the user through a series of steps to define pressure settings and load interaction. Then, the user can rapidly obtain ballpark figures for:

· total flow capacity required

· resonant frequencies of actuation circuits

· power requirement to size the prime mover

· diameters of supply and return lines to optimize flow dynamics, and

· component dimensions (in some cases).

With this tool, users can address the design problem in a hierarchy. First, they define generic mechanical characteristics, which does not require expertise in hydraulics. Next, they evaluate functional alternatives presented by the program, size circuits, and obtain the information necessary to properly select actual components.

Focused Practice

I. Answer the following questions:

1. What does output from the prototype pay special attention to?

2. Where are alternative HPUs described?

3. What does the prototype do once a selection of design options is made?

4. How many choices for actuation circuits does the program provide? 

5. When does the prototype establish all ranking systems as guidelines for the user?

6. How can users address the design problem?

II. Analyse the grammar structures underlined in the above text.

III. Speak on: The ability to automatically size the circuits.

Unit 22

Grammar: Word-building. The Conjunctional
and Prepositional Phrases

Word List:

1. exhaust hood	выхлопной патрубок, вытяжной шкаф
2. transonic flow	поток, проходящий со скоростью звука
3. domain multi-domain	область; многоступенчатый
4. complexity	запутанность, сложность
5. diffuser	распылитель, рассеиватель
6. boundary conditions	граничные условия
7. three-dimensional	трехмерный
8. throughflow	прямой, сквозной поток
9. planes	решетки, подложки под граничным слоем
10. architecture	сеть, структура, строение
11. aerodynamics	аэродинамика
12. finite volume	ограниченный объём
13. mechanical stress	механическое напряжение

The Calculation of a Last Stage Low
Pressure Steam Turbine and Exhaust Hood Flow

In large nuclear steam turbines, the last stage and exhaust hood are very important. Indeed, their high contribution to the total turbine output as well as the critical last stage operating conditions (transonic flow, wet steam, high mechanical stresses, ...) have led to a large number of various studies. Therefore, a greater attention is being devoted to the diffuser designed to recover kinetic energy and to increase last stage efficiency. Moreover, a reduction of diffuser length helps to reduce the shaft length which is always very interesting from the economic point of view.

Obviously, the calculation of a last stage low pressure steam turbine and exhaust hood flow is difficult due to the complexity of three dimensional flow in addition to the multi-domain. Indeed, it is quite impossible to determine appropriate boundary conditions for a local calculation without coupling techniques. A way to solve this problem is to perform a throughflow calculation of the whole cylinder. However, this method is not very useful for the complex low pressure last stage flow and quite impossible for the three-dimensional exhaust hood flow. Another way consists of simultaneously solving the aerodynamic flow problem in the stator, in the rotor and in the exhaust hood. Of course, this method seems very complex and expensive. However, in relation to the modern computers this method is nowadays realistic and very promising in relation to the new parallel architecturecomputers. The last stage flow is always unsteady because of the rotor. The principal assumption is that the flow is steady relative to each domain individually and that each domain can communicate via mixing planes These introduce circumferential averaging of the flow properties, but preserve quite general radial variations.

Focused Practice

I. Answer the following questions:

1. What has led to a large number of various studies?

2. What is a greater attention being devoted to?

3. Why is a reduction of the shaft length very interesting?

4. Why is the calculation of a last stage low pressure steam turbine and exhaust hood flow difficult?

5. What is a way to solve the problem?

6. What does another way consist of?

II. Analyse the grammar structures underlined in the above text.

III. Speak on: Specification of calculatingthe the above equipment.

Unit 23