Academic Writing

Rhetorical functions in academic writing: Including charts and diagrams

It is often useful when you are writing to include reference to tables and charts.

Examples

Example 1

Look at the following example:

Phone sales

Figure 1 shows sales of mobile phones per month. As can be seen, it covers the years 1998 to 2001 and shows that the sales of mobile phones declined steadily in 1998, then remained steady from May until the end of the year. The sales rose more and more steeply, throughout 1999, with a steep increase at the end of the year, and reached a peak of 6,200 in February 2000. A sharp fall followed but sales levelled off at about 5,300 per month in April, fluctuated slightly through the year, and are now increasing again. The figures seem to indicate that we have recovered from the problems in mid-2000 and are on target to improve on our February 2000 peak by the end of 2002.

Usually in such cases, the writer does not simply add the visual to the text, but includes some sort of comment. Typically the writer will include (Swales & Feak, 1994):

  • a few words that locate the visual,
  • a statement that draws attention to the important features of the visual,
  • some sort of comment on or discussion of the visual.

Example 2

Flyball GovernorFigure 12-2 A flyball governor

As shown in Figure 12-2, the flyball governor is connected mechanically to the output shaft of a steam engine so that the ball mechanism rotates at the speed of the engine. If the load on the engine decreases, speed will tend to increase which, through centrifugal action, forces the balls outward. Through the linkage, this will proportionately close off the steam supply to the engine. If the engine tends to lose speed, the mechanism increases the steam supply accordingly. Therefore, the flyball governor maintains engine speed at a preset value without human intervention. This invention is significant in several respects. It is remarkable if for no other reason than it was so advanced for its time (the 1780s). Furthermore, it is a classic illustration of the elegant solution. Finally, it is widely recognized as an outstanding example of what engineers can do without the benefit of theory. The mathematical theory of the behavior of this governor did not appear until 1868

Example 3

The Widening Gap

About 70 percent of the world's population live in the less developed countries. What is more noteworthy about this situation is that the rate of economic growth of the developed countries exceeds the rate of economic growth of the underdeveloped countries, creating an ever-widening gap between the richest and poorest nations, as can be seen from the graph in Figure 20-3. Especially alarming in this regard is the fact that during the decade 1960-1970 agricultural output in the underdeveloped countries increased at an average annual rate of 2.7 percent per year while the population of these countries increased at an annual average rate of 2.8 percent (United Nations 1973), creating an absolute deterioration in their living standards.

(From: Marvin Harris, Culture, people, nature: An introduction to general anthropology. Harper, 1975)

Example 4

Spectra

A typical apparatus used in the measurement of atomic spectra is indicated in figure (5-1). The source consists of an electric discharge passing through a region containing a monatomic gas. Owing to collisions with electrons, and with each other, some of the atoms in the discharge are put into a state in which their total energy is greater than it is in a normal atom. In returning to their normal energy state, the atoms give up their excess energy by emitting electromagnetic radiation. The radiation is collimated by the slit, and then it passes through a prism (or diffraction grating), consequently breaking up into its spectrum, which is recorded on the photographic plate.

(From: Robert Martin Eisberg, Fundamentals of modern physics. Wiley, 1961)

Example 5

Water Discharge

Figure 2 shows long-term monthly means of discharge hydrographs of six gauging stations on the Upper Rhine, Moselle and Saar. These curves allow the respective increases in streamflow between the gauges to be derived due to inflowing tributaries. In the winter months these increases amount to some 300 m3/s between the gauges Rheinfelden and Maxau on the Upper Rhine. The crux of the matter, however, is the fact that the peaks of these flood waves in the tributaries are by far (up to 10 times) higher than the mean monthly discharge increases in the receiving river between these two gauges. Flashfloods in tributaries to the Rhine from the Black Forest and the Vosges Mountains characterise here the genesis of floods in the Rhine. Before river training, the peaks in the tributaries entered the Rhine about 1.5-2 days before the Rhine flood peaks arrived. A similar situation can be observed in the Moselle upstream of Trier, where the Upper Moselle, the Sauer, and the Saar come together. In both cases, typical patterns of flood genesis involve the risk that the impacts of river training on flood-runoff along the Upper Rhine, Moselle and Saar increases downwards of the rivers and are stronger there than immediately at the ends of the canalised reaches.

(From: J. U. Belz, N. Busch, H. Engel and G. Gasber, Comparison of river training measures in the Rhine catchment and their effects on flood behaviour. Proceedings of the Institution of Civil Engineers: Water and Maritime Engineering, 18, 2001, pp. 123-132)

Example 6

Nozzle

Fig. 1 Schematic diagram of experimental set-up for microscopic spray visualization

2 EXPERIMENTAL SET-UP

To investigate the internal structure of transient diesel sprays from a five-hole VCO nozzle, a Bosch common-rail injection system equipped with a CP3 pump was used. A double-guided needle injector was also adopted to ensure the uniformity of the spray between the nozzle holes in the early stage of injection. The diameter of the nozzle exit was 0.144 mm. Using common-rail pressures of 39.5 MPa and 112 MPa, the sprays were injected, under atmospheric ambient conditions, to retard the completion of the break-up and to give easy optical access. Figure 1 shows the schematic diagram of the experimental set-up. The specially designed nozzle cap was mounted so as to face one of the five holes without the optical interference of neighbouring sprays [16]. The nozzle cap allowed only one spray from a hole open for observation, while it bypassed other sprays from four holes without disturbing injection performance. The injection velocity was calculated from the injection rate profiles measured with the Bosch tube method [17, 18].

Using a long-distance microscope and two illumination techniques, the development of the spray was microscopically visualized. First, a laser light sheet formed by an Ar-ion laser was aligned, through two cylindrical lenses to the centre of the spray, and the scattered light was imaged with an intensified charge-coupled device camera whose exposure time (gating time) was 70 ns. The dimensions of the visualized area were about 2 mm x 1.5 mm. Second, a backward illumination technique was applied with a spark light whose effective light duration was about 10 ns, and a high-resolution charge-coupled device camera was used for imaging. The field of view was about 1.2 mm x 1.0 mm. The characteristics of the optics were then calibrated with model particles that ranged in size from 4.8 to 45 am. Because of diffraction phenomena, the light intensity at the particle edge gradually changed. Therefore, the depth of field and the contrast of the small particle images were inferior to those of large particles.

(From: Choongsik Bae and Jinsuk Kang, The structure of a break-up zone in the transient diesel spray of a valve-covered orifice nozzle. International Journal of Engine Research, 7, 2006, pp. 319-334)

Example 7

1-2 CLASSIFICATION OF FORCES

Force is one of the most important of the basic concepts in the study of mechanics of materials (or the mechanics of deformable bodies). Force is the action of one body on another; forces always exist in equal magnitude, opposite direction pairs. Forces may result from direct physical contact between two bodies, or from two bodies that are not in direct contact. For example, consider a person standing on a sidewalk. The person exerts a force on the sidewalk through direct physical contact between the soles of his or her shoes and the sidewalk; the sidewalk in turn exerts an equal magnitude, opposite direction force on the soles of the person's shoes. If the person were to jump, the contact force would vanish but there would still be a gravitational attraction (force between two bodies not in direct contact) between the person and the earth. The gravitational attraction force exerted on the person by the earth is called the weight of the person; an equal magnitude, opposite direction, attraction force is exerted on the earth by the person. Another type of force that exists without direct physical contact is an electromagnetic force.

Force 1

Contact forces are called surface forces, since they exist at surfaces of contact between two bodies. If the area of contact is small compared to the size of the body, the force is called a concentrated force; this type of force is assumed to act at a point. For example, the force applied by a car wheel to the pavement on a bridge (see Fig. 1-1) is often modeled as a concentrated force. Also, a contact force may be distributed over a narrow region in a uniform or non-uniform manner. This situation would exist where floor decking contacts a floor joist, as shown in Fig. 1-2a. Here, the floor decking exerts a uniformly distributed load(force) on the joist, as shown in Fig. 1-2b. The intensity of the distributed load is w and has dimensions of force per unit length.

Other common types of forces are external, internal, applied, and reaction. To illustrate, consider the beam loaded and supported, as shown in Fig. 1-3a. A free-body diagram of the beam is shown in Fig. 1-3b. All forces acting on the free-body diagram are external forces; that is, they represent the interaction between the beam (the object shown in the free-body diagram) and the external world (everything else that has been discarded). Force F is a concentrated force, whereas w is a uniformly distributed load with dimensions of force/length. The forces F and w are calledapplied forces or loads. They are the forces that the beam is designed to carry. ForcesAx, Ay, and are necessary to prevent movement of the beam. Such supporting forces are called reactions. Force distributions at supports are complicated, and reactions are usually modeled as concentrated forces.

Force 2

Force 3

Once again, all the forces shown in Figure 1-3 are external forces. At every section along the beam, there also exists a system of equal magnitude, opposite direction, pairs of internal forces between the atoms on either side of the section. The study of mechanics of materials or mechanics of deformable bodies, depends on the calculation of these internal forces at various sections of a structure or machine element and how these forces are distributed over the sections.

(From: Mechanics of materials, William F. Riley, Leroy D. Sturges & Don H. Morris, Wiley, 1999)

Example 8

Monochord

Fig. 22. The monochord

Experiments with the Monochord

Our source of sound will no longer be a tuning-fork but an instrument which was known to the ancient Greek mathematicians, Pythagoras in particular, and is still to be found in every acoustical laboratory - the monochord.

Its essentials are shown in fig. 22. A wire, with one end A fastened rigidly to a solid framework of wood, passes over a fixed bridge B and a movable bridge C, after which it passes over a freely turning wheel D, its other end supporting a weight W. This weight of course keeps the wire in a state of tension, and we can make the tension as large or small as we please by altering the weight. Only the piece BC of the string is set into vibration, and as the bridge C can be moved backwards and forwards, this can be made of any length we please. It can be set in vibration in a variety of ways - by striking it, as in the piano; by stroking it with a bow, as in the violin; by plucking it, as in the harp; possibly even by blowing over it as in the Aeolian harp, or as the wind makes the telegraph wires whistle on a cold windy day.

(From: James Jeans, Science and music. Cambridge University Press, 1937)

Example 9

Saturation Water Vapour Density.

Considered from the point of view of the kinetic theory of matter, evaporation occurs because of the tendency for pure liquid water to establish a dynamic equilibrium with the water vapour concentration in the atmosphere in contact with it. At standard pressure and in a closed system, the equilibrium water vapour concentration over pure water will be at a specific partial pressure or the so-called saturation water vapour pressure. Table 1.2 shows that the saturation water vapour pressure increases with increasing temperature. At the critical temperature (in the case of water, 100°C), the vapour pressure of liquid water is the same as the saturation water vapour pressure of the atmosphere. The critical temperature for water at a pressure of 1 bar is 100°C and, above the critical temperature for a given pressure, liquid water cannot exist.

Table 1.2.  Saturation water vapour pressures (SWVP) and the corresponding saturation water vapour densities (SWVD) at different temperatures

               
 

5°C

10°C

15°C

20°C

25°C

30°C

35°C

SWVP (mbar)

8.72

12.27

17.04

23.37

31.67

42.43

56.23

SWVD (g m-3)

6.74

9.39

12.83

17.30

23.00

30.38

39.63

(From: Hans Meidner & David W. Sheriff, Water and plants. Blackie, 1976)

Example 10

Table 2.6 illustrates clearly the extent to which the flora of selected islands now contain alien species, with the percentage varying between about one-quarter and two-thirds of the total number of species present.

Table 2.6.  Alien plant species on ocean islands

Island

Number of native species

Number of alien species

% of alien species in flora

New Zealand

1200

1700

58.6

Campbell Island

128

81

39.0

South Georgia

26

54

67.5

Kerguelan

29

33

53.2

Tristan da Cunha

70

97

58.6

Falklands

160

89

35.7

Tierra del Fuego

430

128

23.0

(From: Andrew Goudie, The human impact on the natural environment. Basil Blackwell, 1981)

Example 11

Table 4.2 gives an example of an engineering curriculum. Such a curriculum does not tend to vary significantly among colleges and universities or engineering disciplines. Note that the curriculum described adheres to the requirements of ABET. That curriculum is based on the semester system. Many universities operate on the quarter system in which the academic year is divided into three periods of about 12 weeks duration. A quarter-based-curriculum would of course be "packaged" differently but would be similar to one based on the semester system.

Table 4.2  Typical Freshman Engineering Curriculum

 

Semester Hours Credit

Freshman Year Courses

1st Semester

2nd Semester

CHEM 101 - General Chemistry

4

-

CHEM 102 - General Chemistry

-

4

MATH 120 - Calculus and Analytical Geometry

5

-

MATH 132 - Calculus and Analytical Geometry

-

3

Elective in Social Science or Humanities

3

3

GE 103 - Engineering Graphics

3

-

RHET 105 - Principles of Composition

-

4

ENG 100 - Engineering Lecture

0

-

CE 195 - Introduction to Engineering

-

0

PHYSICS 106 - General Physics (Mechanics)

-

4

TOTALS

15

15

(From: Paul H Wright, An introduction to engineering. Wiley, 1989)

Example 12

Most programming languages require that a declarative statement that introduces a variable also specify the type of data that will be referenced by that variable. Figure 5.5 gives examples of such declarative statements in Pascal, C, C++, Java, and FORTRAN. In each case the variables Length and Width are declared to be of type real, and PriceTax, and Total are declared to be of type integer. Note that C, C++, and Java use the term float to refer to the type real, since data of this type are represented in floating-point notation.

Variable Declarations

(From: J. Glenn Brookshear, Computer science: An overview. Addison-Wesley, 1997)

Example 13

Equation

(From: Mechanics of materials, William F. Riley, Leroy D. Sturges & Don H. Morris, Wiley, 1999)

Example 14

Air Turbidity

Figure 7.6 shows that the average turbidity factor for the atmosphere (Linke turbidity) has increased by 30 per cent in a decade (the dot-and-dash line). It also shows the effect of a natural source of turbidity, the Mount Agung (Bali) eruption of 1963 (the single, continuous line). In the figure the dotted line represents the linear trend for the same period if the effects of the eruption are excluded from the computations.

(From: Andrew Goudie, The human impact on the natural environment. Basil Blackwell, 1981)

Example 14

The Lewinian Experiential Learning Model

The Lewinian Model of Action Research and Laboratory Training

In the techniques of action research and the laboratory method, learning, change, and growth are seen to be facilitated best by an integrated process that begins with here-and-now experience followed by collection of data and observations about that experience. The data are then analyzed and the conclusions of this analysis are fed back to the actors in the experience for their use in the modification of their behavior and choice of new experiences. Learning is thus conceived as a four-stage cycle, as shown in Figure 2.1. Immediate concrete experience is the basis for observation and reflection. These observations are assimilated into a "theory" from which new implications for action can be deduced. These implications or hypotheses then serve as guides in acting to create new experiences.

(From: David A.Kolb, Experiential learning. Prentice Hall, 1984)

Example 15

Isogloss

Linguists use the term isogloss to refer to the geographical boundary of a linguistic trait. Even within a relatively homogeneous speech area, quite a large number of isoglosses can be traced. 'lucre is no necessary relation between any one isogloss and any other; they crisscross and diverge and often present a rather bewildering picture.

Figure 3.3 is a conceivable linguistic map on which three isoglosses are marked. The linguistic traits in question arc lexical ones. Sonic speakers call a certain sparrow-like bird found in the region finu; others use the word tawen to designate this kind of bird. The isogloss running vertically demarcates roughly the subareas characterized by these alternate lexical items - speakers to the left of this line in general use finu, while those to the right use tawen. Similarly, thestanu/lufa and the sen/iktaw isoglosses indicate the extensions of the use of alternate lexical items.

The three isoglosses divide the region represented in Figure 3.3 into six subregions, each of which is distinct from the other five. In one subregion, speakers usefinustanu, and sen; in another they use tawenstanu, and sen. Where, then, is there a dialect boundary? There is really no satisfactory answer to this question. Dialect boundaries are established on the basis of different linguistic traits, but the three linguistic traits indicated in Figure 3.3 contradict one another as to where a dialect boundary lies. The dividing line will be drawn in one place if the criterion is the finu/tawen distinction, in another if it is the stanu/lufa alternation, and in still another if it is the sen/iktaw distinction. If we added more isoglosses to Figure 3.3, the situation would be worse yet.

One way out of the difficulty is to say that six dialect areas are represented in Figure 3.3, not two. In other words, we can define a dialect in such a way that two people speak different dialects if their linguistic systems differ with respect to at least one trait. Thus a person from the finu/lufa/sen area speaks a different dialect from the one spoken by a person from the tawen/lufa/sen area, since one person uses finu while the other uses tawen.

(From: Ronald W. Langacker, Language and its structure, Harcourt, Brace, Jovanovich, 1967)

Example 16

The Physics of Speech

One form in which sound spectra are often shown is illustrated in Fig. 26. Frequencies are set out on the horizontal scale in hertz. The relative amplitude of the components is given with reference to the vertical scale; the component with the greatest amplitude is given the value 1.0 and the amplitude of all other components is expressed as a proportion of this value. Wherever a vertical line is drawn, there is a component of that frequency present in the mixture with the amplitude indicated; at all other frequencies there is zero sound energy. The two examples are the bass C of the piano, one octave below middle C, with a fundamental frequency of 132 Hz and middle C played on the clarinet, fundamental 264 Hz. In each case any components represented in the spectrum must be in the harmonic series and consecutive harmonics will appear at an interval equal to the fundamental frequency. In the piano note consecutive harmonics occur over a wide frequency range and since the fundamental is low they appear close together. The fundamental of the clarinet note is an octave higher and therefore the distance between consecutive harmonics is doubled. It is only from about 1500 Hz upwards that consecutive harmonics appear in the clarinet tone ; the second and fourth harmonics have zero amplitude. There are major differences in the mechanisms for generating sound in the piano and the clarinet : the piano tone is the result of free vibrations of the piano string which is struck by a hammer while the air column of the clarinet is performing forced vibrations in response to the continued vibration of the reed and does not show the rapid damping of the sound which is so characteristic of the piano. Nonetheless the differences in spectrum which appear in Fig. 26 are largely responsible for the difference in sound quality which we hear between the two instrument

(From: D. B. Fry, The physics of speech, Cambridge University Press, 1979)

Language

Referring to a diagram, chart etc.

As can be seen

from
in

the

chart,
diagram,
table,
graph,
figures,
statistics,

...

It can be seen
We can see

that ...

 

...

can be seen

from
in

the

chart.
diagram.
table.
graph.
figures.
statistics.

is shown

 

As can be seen

from
in

Table 1,
Figure 2,
Graph 3,

.

It can be seen
We can see

 

From

Table 1
Figure 2

it

can

may

be

seen
concluded
shown
estimated
calculated
inferred

that ...

the

figures
chart
diagram

 

The graph
Figure 1

shows

that ...

Describing change

There was a(n) (very)

barely noticeable
slight
slow
gradual
steady
marked
dramatic
steep
sharp
rapid
sudden

rise.
increase.
upward tend.

fluctuation.

downward trend.
decrease.
decline.
reduction.
fall.
drop.

 

There was a(n)

rise
increase

of

...

decrease
decline
reduction
fall
drop

 

X

increased
shot up
grew
rose

by

...

declined
reduced
decreased
dropped
fell

 

X

increased
shot up
grew
rose

slightly
slowly
gradually
steadily
markedly
dramatically
steeply
sharply
rapidly
suddenly

declined
reduced
decreased
dropped
fell

 

X

reached a peak.
levelled off

 

Note:

It is usual in English to write, for example, "Inflation increased by 8% last year", not "Inflation was increased by 10%". See: Accuracy: Proof Reading Ergative Verbs for more information.

Exercises

Exercise 1
Exercise 2
Exercise 3
Exercise 4
Exercise 5
Exercise 6
Exercise 7