Grammar: Simple, Progressive and Perfect Tenses. The Infinitive

Word List:

1. magnetoresistive materials	магниторезистивные материалы
2. magnetic recording heads	записывающие магнитные головки
3. disk drive	дисковый накопитель
4. storage requirements for applications	требования к объему сохранения данных для различных применений
5. giant magnetoresistive materials	материалы с очень большим магнитным сопротивлением
6. tunneling device	прибор, работающий на основе туннельного эффекта
7. fringing fields	краевые поля
8. write pole	записывающий полюс
9. write coils	записывающие катушки
10. read width	ширина считывания

Impact of New Magnetoresistive Materials
on Magnetic Recording Heads

Magnetoresistive recording heads have only recently been introduced into the magnetic recording industry but they have heralded a new interest in the basic properties of magnetic materials. What is driving this interest is the direct link between the magnitude of the magnetoresistance of the sensor material and the final storage capacity of the disk drive. With the storage requirements for applications increasing rapidly it is not surprising that there has been a keen interest in pushing materials to larger magnetoresistance. New multilayer films, for example the giant magnetoresistive materials, are being developed with a variety of properties that can be tailored to meet the needs of the new technology. Other novel sensors have been proposed, for instance tunneling devices which depend on the tunneling of electrons from one magnetic layer to another, and colossal magnetoresistive materials which have a structure similar to high Ts superconductors. With the phenomenon of electron transport at small length scales becoming better understood it is well within possibility that a “magnetic switch” is only just around the corner.

In an example of a typical magnetoresistive (MR) head geometry that could be used to achieve 16 Mb/mm² sandwiched between shields is a magnetoresistive element with two conductors that make contact with the MR element. A sense current is used to measure the change in resistance of the element as a recorded bit in the media passes underneath the head. The bits are written by fringing fields that jump the gap between the write pole and the shield when current is applied to the write coils.

The read widthin this particular head geometry is defined by the region of the element that is sensed by the two contacts. The distance between the shields controls the resolution of the sensor along the track. The distance from the bottom of the sensor to the top of the magnetic layer in the media is defined as the magnetic spacing.

Focused Practice

I. Answer the following questions:

1. Why have magnetoresistive recording heads heralded a new interest in the basic properties of magnetic materials?

2. Why has there been a keen interest in pushing materials to larger magnetoresistance?

3. How are new multilayer films being developed?

4. What other novel sensors have been proposed?

5. What is a sense current used for?

6. What controls the resolution of the sensor along the track?

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

III. Speak on: Magnetoresistive recording heads.

Unit 13

Grammar: The Gerund

Word List:

1. membrane	мембрана, пленка
2. desalination	опреснение
3. reverse osmosis	обратный осмос (обратная диффузия)
4. quantum leap	количественный скачок
5. trend	направление, тенденция
6. osmotic pressure	осмотическое давление
7. rather than	а не; скорее...чем
8. porous sublayer	пористый подслой
9. in situ	на месте
10. as compared to	по сравнению с
11. tolerance	стойкость, выносливость

Progress in Membrane Science and Technology for Seawater Desalination

Membrane technologies have been incessantly progressing during the past forty years. No limit in the future progress is currently in sight. Contributions to membrane science and technology, upon reaching a critical mass, will result in another quantum leap that is equivalent to the historic announcement of the Loeb-Sourirajan membrane in nineteen sixty. There are some new trends observable in the following four areas: membrane development, membrane characterization, membrane transport and membrane system design. Membrane development deals with recent progresses in the development of reverse osmosis membranes used for desalination.

To increase the pure water recovery by a membrane module from the conventional 40 % to 60 % is a trend observable in seawater desalination technology. Since the osmotic pressure of the retentate will increase from 4.5 to 7.0 MPa when the water recovery increases from 40 to 60 %, the development of a high pressure vessel as well as the development of a membrane that will show little compaction under a high pressure is necessary. Kawada reported recently on the development of a reverse osmosis membrane that was suitable for operation at 9 MPa. He found that membrane compaction took place at the porous sublayer rather than at the skin layer. An attempt was therefore made to reduce the compaction by making a large number of uniform pores of small sizes at the surface of the porous sublayer on which an aromatic polyamide skin layer was coated by in-situ polycondensation.

The stability of the membrane module productivity increased significantly as compared to the conventional seawater desalination membrane.

One of the drawbacks of composite membranes based on aromatic polyamide is poor chlorine tolerance. Many attempts have been made to improve the chlorine resistance of composite membranes by changing the molecular structure of the monomers used for the polymerization. A patent was recently issued on a composite membrane that is chlorine resistant.

Focused Practice

I. Answer the following questions:

1. What new trends are there in membrane technologies?

2. What does membrane development deal with?

3. Where does membrane compaction take place?

4. What was made to reduce the compaction?

5. What is one of the drawbacks of composite membranes?

6. What attempts have been made to improve the chlorine resistance of composite membranes?

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

III. Speak on: One of the drawbacks of composite membranes.

Unit 14

Grammar: The Passive Voice

Word List:

1. turbulent combustion	турбулентное сгорание
2. chemical reaction rate	скорость химической реакции
3. thin reaction sheets	емкость из тонкостенных листов
4. length scale	линейный масштаб
5. disparity	несоразмерность, несоответствие, различие
6. by and large	вообще говоря
7. flame	пламя; факел пламени
8. with respect to	в отношении, что касается
9. velocity	вектор скорости
10. to exploit	использовать

Asymptotic Methods in Turbulent Combustion

There are a number of different regimes of turbulent combustion, dependent upon the intensity and scales of the turbulence, measured with respect to suitable combustion parameters derived from the chemical reaction rates. In one set of these regimes, combustion occurs in thin reaction sheets, transported and distorted by the turbulence. In these reaction sheet regimes, more than one characteristic length scale is involved in the turbulent combustion; there are short scales associated with the chemical processes and long scales associated with the turbulence. The disparity of scales causes asymptotic methods to be advantageous for studying turbulent combustion in reaction sheet regimes. A significant amount of progress has been made recently by use of asymptotic methods for describing these regimes in both premixed and nonpremixed turbulent combustion. By and large, the objectives have been not to calculate the turbulent reacting flows completely, but rather to relate the properties of interest in these flows to properties of nonreacting turbulent flows. It then becomes possible to use the existing methods of analysis of nonreacting flows to calculate the results of interest for turbulent combustion. The intent of the present paper is to review the recent advances achieved by use of the methods described above and to identify not only what is known but also areas of unknowns for future research. Other reviews covering material of this type have been published.

The techniques employed in analyzing turbulent combustion differ for premixed and nonpremixed systems. This is especially true in various finer details of analyses of reaction sheet regimes. Therefore, it will be convenient here to treat turbulent premixed flames and turbulent diffusion flames separately. Presentations more unified in character may become appropriate in the future since there are a number of similarities, e.g., the reaction sheet aspect itself. However, it seems likely that certain essential differences will remain; burning velocities exist for premixed but not for nonpremixed combustion (at least not in the same sense).

In recent years asymptotic methods have contributed greatly to an improved understanding of turbulent combustion in both premixed and nonpremixed systems. These methods must be incorporated into flowfield calculations before they can be fully exploited.

Focused Practice

I. Answer the following questions:

1. What do different regimes of turbulent combustion depend upon?

2. What are asymptotic methods used for?

3. Why is it convenient to treat turbulent premixed flames and turbulent diffusion flames separately?

4. What presentations may become appropriate in the future?

5. What combustion do burning velocities exist for?

6. When can asymptotic methods be fully exploited?

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

III. Speak on: The reaction sheet regimes.

Unit 15