1179 Slices
Medium 9789381159620

Chp-3

Dr. Aminul Islam Laskar Laxmi Publications PDF

Chapter

3

Aggregates and Water

Aggregates are those parts of concrete that constitute the bulk of the finished product. They comprise 60%–80% of the total volume of concrete and have to be so chosen that the entire mass of concrete acts as relatively solid, homogenous, dense combination, with the smaller sizes acting as an inert filler of the voids that exist between the larger particles. Aggregates are of two types:

1.

Coarse aggregate such as gravel, crushed stone or blast furnace slag;

2.

Fine aggregate such as natural or manufactured sand.

Since the aggregates constitute the major portion of the mixture, the more the aggregate in concrete, the cheaper is the concrete, provided that the mixture is of reasonable workability for the specified job for which it is used.

COARSE AGGREGATE

Coarse aggregate is classified as such if the smallest size of the particle is greater than 4.75 mm.

Properties of the coarse aggregate affect the final strength of hardened concrete and its resistance to disintegration, weathering, and other destructive effects. The mineral coarse aggregate must be clean of organic impurities and must bond well with the cement gel. The common types of coarse aggregate are:

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Medium 9789380386324

LAX2-2

Dr. A.J. Nair Laxmi Publications PDF

FUNDAMENTALS

OF

BIOCHEMICAL ENGINEERING

!'

For example, measurements such as area, volume, velocity, etc. are derived from base quantities or fundamental quantities.

Area

= length × length

Volume

= length × length × length

Velocity

= distance/time

Units

Physical variables are measured against certain standards known as units. Base units are those used to express the dimensions or the fundamental quantities, and the derived units are those derived from the fundamental or base units. There are different systems of units such as MKS,

CGS, SI, and FPS units. Units of one system can be converted into units of another system. SI units is the officially accepted system and is widely in use. There are two clusterings of metric units in science and engineering. One cluster, based on the centimeter, the gram, and the second, is called the CGS system. The other, based on the meter, kilogram, and second, is called the MKS system.

Similarly, FPS system is the old British system that uses foot, pound, and second as the basic units.

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Medium 9789383828562

Part IIIMQ-Paper - 1

Dr K.Sivarajan; Dr C.N.Balakrishnan Nambiar Laxmi Publications PDF

Model Question Papers for Practice Test

757

MODEL QUESTION PAPER - 1

Note : This paper contains sixty (60) multiple choice questions, each carrying two (2) marks. Answer any fifty (50) questions. The total time for answering the paper is 75 minutes and the total marks for the paper is 100.

1.

ABCDE and F are sitting in a row. C is between A and B and is fourth from the right. D is fifth from the left. E is to the right of D. Who is seated on the left side of D?

A. A

B. B

C. C

D. E

2.

Among four friends PQR and S, Q is taller than S only. R is taller than P.

Who among them is the tallest?

A. P

B. Q

C. R

D. S

3.

The total age of nine friends is 243 years. What will be the average age of these friends after 4 years?

A. 27

B. 25

C. 31

D. 21

4.

The word AMERICA is coded as IUMZQKI. What will be the code for

BLACK?

A. JTIKS

B. TJISK

C. JWXZT

D. JTSKI

5.

BADC: FEHG:: JILK:....?

A. IJKL

B. MNOP

C. NMPO

D. KLMN

6.

What is the fourth term of the series 8712, 7623, 6534, ......, 4356, ......

A. 7623

B. 5445

C. 6512

D. 4358

7.

There is a group of persons consisting of Doctors, Engineers and Teachers in Medical and Engineering Colleges. Which diagram represents the group?

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Ch_10

Dr. V.N. Kala; Rajeshri Rana Laxmi Publications PDF

142

10.3

MATRICES

DIFFERENCE BETWEEN MATRICES AND DETERMINANT

The following are differences between matrix and a determinant :

1. In a matrix, the number of rows may or may not be equal to the number of columns while in case of a determinant, we always have, the number of rows equal to the number of columns.

2. A matrix can be reduced to a number while in a determinant it cannot be reduced to a number.

3. In a matrix, interchange of rows and columns can change the matrix while in the case of a determinant, interchange of rows and columns does not change the value of determinant.

10.4

DETERMINANT : IT�S GENERAL DEFINITION :

LL a12 a13

é a11

êa a22 LL LL

21

Let there exists a square matrix A such that A = ê

ê M

M

M

ê an 2 LL LL

ë an1 positive integer, then determinant of A, denoted by | A | is defined as :

|A|=

å± a

1i a2 j a3 k

a1n ù a2 n úú where n is a

M ú

ú ann û

LL ant

where (+) ve or (– ve) sign is taken in accordance as i, j, k, ......, t is an even or odd permutation of

1, 2, ......, n the summation being extended over all the possible Ðn permutations of the row subscripts

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Ch_2_F

K.V.S.G. Murali Krishna Laxmi Publications PDF

Sources of Air Pollution

17

2

SOURCES OF AIR

POLLUTION

One of the early steps involving air pollution problems is to locate the source from which air contaminants are being emitted. There are more than 7,50,000 man-made chemicals present in our environment and to these 1000�2000 new ones are added every year. Massive production of such chemicals directly or indirectly releases thousands of tonnes of a variety of air pollutants into the atmosphere. Some of the air pollutants emanated into the atmosphere by man are CO, CO2, SPM,

SOx, odours, noise, NH3, gases and vapours, dusts of toxic metals like Lead, Arsenic, Asbestos,

Nickel, Mercury, Phosphorus and their oxides, Vanadium, Zinc, various hydrocarbons, Fluorides etc. The pollution made by man is vast and the pollutants made by men are plentiful.

2.1 CLASSIFICATION OF AIR POLLUTANTS

Air pollutants and their sources may be classified as follows:

∑ Primary and secondary pollutants

∑ Line and areal sources

∑ Natural and artificial sources.

2.2 PRIMARY AND SECONDARY POLLUTANTS

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