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International Journal of Agriculture and Environmental Research

ISSN: 2455-6939

Volume:02, Issue:03

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ERGONOMICAL EVALUATION OF SELECTED MANUALLY

OPERATED COCONUT DEHUSKERS

P. P. Pawase2, R. R. Kadam3 and K. G. Dhande1

1Associate Professor, Department of Farm Machinery and Power, College of Agricultural Engineering and

Technology, Dapoli, Dist- Ratnagiri, Maharashtra

2Graduate Student, College of Agricultural Engineering and Technology, Dapoli, Dist-Ratnagiri, Maharashtra

3Graduate Student, College of Agricultural Engineering and Technology, Dapoli, Dist-Ratnagiri, Maharashtra

ABSTRACT

The ergonomical study of a folding type and non-folding type manually operated coconut

dehuskers was carried out at College of Agricultural Engineering and Technology, Dapoli for its

suitability to farmers on the basis of dehusking capacity, dehusking efficiency, damage

percentage and ergonomical considerations like heart rate, oxygen consumption rate, energy cost

of operation, acceptable work load, overall discomfort rating (ODR) and body part discomfort

score (BPDS) during operation. Dehusking of coconut is drudgerous operation. To reduce

drudgery in the dehusking operation, Dr. B. S. Konkan Krishi Vidyapeeth, Dapoli developed two

types of coconut dehuskers, one is folding type and another is non-folding type manually

operated dehusker. The performance of folding and non-folding type manually operated coconut

dehusker was evaluated. The dehusking capacity and dehusking efficiency for folding and non

type coconut dehusker were observed as 58 nuts/h and 93.7 % and 52 nuts/h and 93 %

respectively. No damage to coconut shell dehusked were observed with both type. The average

energy cost of operation of subjects while coconut dehusking with folding and non-folding type

coconut dehuskers were 4.29 and 4.82 Kcal/min respectively. The average oxygen consumption

rate as per cent VO2 max while operating folding and non-folding type coconut dehusker were

9.255 and 10.322 l/min respectively. The coconut dehusking operation with folding and non-

folding type coconut dehusker was within acceptable workload limit. The average ∆HR value

for subjects while coconut dehusking with folding and non- folding type coconut dehuskers were

26.97 and 31.19 bpm respectively which was less than limit of continuous performance (LCP).


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The mean value of overall discomfort rating of subjects for coconut dehusking operation with

folding and non-folding type dehuskers was 3 (light discomfort) and 4 (more than light

discomfort) respectively. The average BPDS score while performing the coconut dehusking

operation using folding type and non-folding type manually operated coconut dehusker was 5.8

and 6.1 respectively.

Keywords: Coconut dehusker, Dehusking capacity, Dehusking efficiency, oxygen consumption

rate, Limit of continuous performance, ODR, BPDS, energy expenditure rate, acceptable

workload

INTRODUCTION

Although coconut is of immense economic importance to both the industrialist and rural area,

separation of its husk from the nut (dehusking) constitutes the first, most difficult and drugerous

operation in its processing. Dehusking is the process of removing the outer covering called husk

from the coconut to get two important commercial products such as copra or dried kernel and

fibre or coir. The coconut reaching markets are either partially husked or dehusked as per

demand and requirement in distant market. Coconuts meant for distant market place are left with

some fibre covering the eyes or on all around the nuts. Such partially husked minimizes the

breakage during transportation and attains longer keeping quality. Coconut dehusking is the first

step in the preparation of coconut for the fresh market. Dehusking is done manually by impairing

the coconut on a sharp iron or wooden spike fixed to the ground.

The most frequently used dehusking method is by the use of pointed metal spike, secured in the

ground in a slightly slanting position, with the pointed ends upward (Mishra and Sutar, 2007).

The nuts are brought down with force on the spike, followed by twisting the nut sideward against

the spike, causing loosening of the husk. Care is taken for the desired entry of the sharp end of

the spike into the husk so as to avoid the damaging of shell. It is, therefore, clear that dehusking

is a hard work, and may cause frequent injury to the operator. This process is laborious and time

consuming, moreover it requires skilled laborer.

A folding type manually operated coconut dehusker and non-folding type coconut dehuskers

were developed at Dr. B S KKV, Dapoli which can be easily transported and safe for operation

with reduced the drudgery. The performance and ergonomic evaluation of developed dehusker

for its workload on operator, necessity of work rest cycle if needed for continuous performance,

estimate energy cost of dehusking operation, assess whether workload is within acceptable limit

be evaluated. To assess the ease of coconut dehusking operation by coconut dehusker and


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drudgery cause in term of Overall discomfort rating (ODR) and Body part discomfort score

(BPDS) be evaluated.

MATERIAL AND METHODS

Constructional details of manually operated Coconut Dehusker

The Dr. Bala saheb Sawant Konkan Krishi Vidyapeeth, Dapoli developed folding and non-

folding type of coconut dehusker was selected for study. Folding type manually operated coconut

dehusking unit selected for study consists of foldable base platform, pole, spike blade, detachable

handle with grip for easy handling and transportation. Non-folding type manually operated

coconut dehusking unit selected for study consists of base platform, pole, spike blade and handle.

The both type of the dehusker selected for the experimental purpose as shown in Fig. 1 and Fig.

2 respectively. Specifications of manually operated coconut dehusker are given in Table 1.

Table 1 Specification of manually operated Coconut Dehuskers

Sr.

No. Particulars

Type A Type B

Non-folding Folding

1 Base Platform 200 × 170 × 30

(M. S.)

185 × 335 × 25

(M.S. flat 25 × 4 )

2 Pole 600 (M.S.) 760 × 38 × 38 , 1.5

Thick

3 Blade Case hardened

Steel, Angle- 600

65 × 35, 4 thick, tip

Width 20 (2 Nos.)

4 Handle Ø 12, 450 (M.S) Ø 12 , 470 (M.S)

Detachable

5 Grip - Ø 26. 120 (Plastic)

6 Hinge - Ø 12, 85 with 17

OD pipe (2 Nos.)

7 Overall

dimensions 200 × 665 185 × 820 × 480

8 Weight 2.90 kg 2.95 kg

9 Size after

Folding Non-foldable 185 × 820 × 100

(All dimensions are in mm)


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Fig. 1 Folding type coconut dehusker

Fig. 2 Non-folding type coconut dehusker


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Operation of manually operated coconut dehusker

The both type of coconut dehusker has one fixed and one movable blade. At normal position,

both the blades are works as one unit. The nuts are brought down with force on the blade. After

pierce of blade into husk, handle is lifted up which loosen the husk. To completely loosen the

husk of coconut, 4-5 strokes have to be given at different positions. After loosening of husk, the

loosen husk can be removed manually. Care is taken for the desired entry of the sharp end of the

blade into the husk so as to avoid the damage to shell. The coconuts variety Banawali cultiver is

selected for performance evaluation. The moisture content of seeds selected for dehusking was in

range of 15-20 % (wb). The number of coconut dehusks per hour, damage percentage and

dehusking efficiency was determined by formulae given below. The experiment was conducted

with ten different operators.

Performance evaluation of Coconut dehusker

1. Moisture content

Moisture content of husk is determined by oven drying method as described in ASAE (1982)

standards. Moisture content is calculated by using following formulae (Ghoshal and Mohanty,

2011)

Moisture Content, wet basis (wb) = Weight of moist material−Weight of dry material

Weight of total material X100

Moisture Content, dry basis (db) = Weight of moist material−Weight of dry material

Weight of dry material X 100

2. Dehusking capacity and efficiency

The dehusking capacity and efficiency of the coconut dehusker were evaluated using ten

experimental tests. Each test involved operating the dehusker by a different operator. The fifty

coconuts were dehusked by each operator and time required for dehusking nuts was recorded.

The dehusked husk obtained and total husk in the five selected coconuts were weighed and

recorded. Thereafter, the efficiency and capacity of the machine were computed in each case

using the following relationship as given by Nwankwojike et al., 2012.


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Dehusking capacity,nut/hr = Number of coconuts dehusked

Time,hr

Dehusking efficiency, % = Weight of husk obtained after dehusking

Weight of total husk present in the coconut X 100

3. Damage percentage

The damage percentage of the coconut dehusked was evaluated using ten experimental tests.

Each test involved operating the dehusker by a different operator and recording of the total

number of fruits dehusked in a given time. During dehusking process, the total number of

damage fruit by each operator was recorded. The damage percentage of the dehusked coconut

was computed in each case using the following relationship as given by Nwankwojike et al.,

2012.

Damage percentage, % = Number of damage coconuts

Total coconuts X 100

Ergonomic Evaluation of Manually Operated Coconut Dehusker

1. The ten male operators (subjects) for dehusking the coconut were selected as dehusking

of coconut is mostly done by male workers.

2. Then each subject was calibrated in the laboratory at sub maximal loads.

3. The value of heart rate at resting level and 6th to 15th minute of operation were taken for

calculating the physiological responses of the subjects (Tiwari and Gite, 1998).

4. Each subject was asked to dehusked coconut up to 25 min with including 5 min for

resting and recovery continuously and during dehusking operation, the HR of subject was

recorded by using polar heart rate monitor.

5. From the values of heart rate (HR) observed during the trials, the corresponding values of

oxygen consumption rate (VO2) of the subjects for all the coconut dehusker were

predicted from the calibration chart of the subjects.


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6. The energy cost of operation of the coconut dehusker was computed by multiplying the

oxygen consumed by the subject during trial period with the calorific value of oxygen as

20.88 kJ l-1 (Nag et al., 1980) for all the subjects.

7. The acceptable workload (AWL) for Indian workers was the work consuming 35 per cent

of VO2 max (Saha et al., 1979). To ascertain whether the operation of all the coconut

dehuskers is within the acceptable workload (AWL), the VO2 maximum for each

treatment was computed and recorded.

8. To have a meaningful comparison of physiological response ∆HR values (Increase over

resting values) for heart rate (work pulse) was calculated (Tiwari and Gite, 1998). The

mean values of the heart rate at rest level and at working condition were used.

9. For the assessment of overall discomfort rating, a 10 – point psychophysical rating scale

(0 – no discomfort, 10 – extreme discomfort) was used and a body map technique was

used to assess the body part discomfort score which were an adoption of Corlett and

Bishop (1976) technique.

10. Based on energy expenditure rate (EER), acceptable workload (AWL), ∆ HR value, VO2

max value, overall discomfort rating (ODR) and body part discomfort score (BPDS), the

energy grade of coconut dehusking operation with selected coconut dehuskers were

evaluated.

RESULTS AND DISCUSSION

It is observed that folding type coconut dehusker perform better than non-folding type coconut

dehusker. The dehusking capacity and dehusking efficiency for folding and non-folding type

were found to be 58 nuts/h, 93.7 % and 52 nuts/h, 93 % respectively. No damage was observed

during operation by both the dehuskers. This may be due to higher height of vertical trunk/post,

comfortable handle grip and sufficient footrest platform to hold coconut dehusker rigidly.

Ten male subjects were selected for the ergonomic investigation of manually operated coconut

dehusker. They were selected on the basis of age, stature, body weight. The details of selected

subjects for the investigation of coconut dehusker are given in Table 2.The age group of the

selected subject varied from 21 and 50 years. The average values of stature and weight of

selected subjects were 165.46 cm and 54.39 kg respectively. The average heart rates at rest of the

selected subjects are varied from 94.48 to 118.49 bpm. The predicted average VO2 at rest of the

selected ten subjects varied from 0.650 l/min to 1.30 l/min. The average value of VO2 at rest of


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selected subjects was 0.865 l/min. The maximum heart rates of the selected subjects are varied

from 170 to 199 bpm. The mean value of maximum heart rate of selected subjects was 184 bpm.

The predicted maximum aerobic capacity of the selected ten subjects valid from 1.9 l/min to

3.405 l/min. The average value of VO2 max of selected subjects was 3.003 l/min.

Table 2 Physiological parameters of subjects participated in manually operated coconut

dehuskers ergonomical evaluation

Subject Age,

years

Stature,

cm

Body

weight,

kg

Average heart

Rate at rest,

bpm

Average

VO2,

l/min

HR

(max),

bpm

VO2

(max),

l/min

1 44 160 49 102.1102 0.925 176 2.480

2 33 173 72.11 106.818 1.30 187 3.201

3 21 159 44 114.42 0.750 199 1.900

4 33 163 63 115.15 0.785 187 3.350

5 50 162 52 107.362 0.690 170 2.510

6 33 162.1 57.38 98.07 0.650 187 3.400

7 21 174 78 118.49 0.850 199 3.105

8 39 176 73 94.48 0.650 181 3.405

9 44 163.5 57.85 104.30 0.950 176 3.330

10 40 162 60 104.04 1.100 180 3.350

Mean 35.8 165.46 54.39 106.52 0.865 184 3.003

Table 3 Recorded values of heart rate and predicted values of oxygen consumption of

subjects for folding and non-folding type manually operated coconut dehusker

Subject Folding type Non-folding type

HR ,bpm VO2 ,l/min HR ,bpm VO2 , l/min

1 102.1102 0.925 105.67 0.950

2 106.818 1.30 112.5 1.40

3 114.42 0.750 115.62 0.760

4 115.15 0.785 117.98 0.770


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5 107.362 0.690 108.529 0.700

6 98.07 0.650 105.03 0.700

7 118.49 0.850 122.37 0.900

8 94.48 0.650 99.23 0.700

9 104.30 0.950 110.23 1.050

10 104.04 1.100 111.95 1.30

Mean 106.4 0.865 110.9 0.923

The mean values of the heart rate from 6th to 15th minutes of operation and the predicted values

of oxygen consumption for all the selected subjects are shown in Table 3. It is observed that the

working heart rate of selected subjects while operating folding and non-folding type coconut

dehusker varied from 94 to 118 bpm and 99 to 122 bpm respectively. The mean value of working

heart rate of all the selected subjects for folding and non-folding type was 106.4 bpm and 110.9

bpm respectively. It is observed that the difference between working heart beats and resting heart

beats is below 40 in all subjects for operating both the coconut dehusker, hence all subjects are

suitable for doing coconut dehusking for continuously. The corresponding oxygen consumption

values of all selected subjects for operating folding and non-folding type coconut dehusker was

0.650 to 1.30 l/min and 0.700 to 1.40 l/min respectively. The mean value of corresponding

oxygen consumption was 0.865 l/min for folding type and 0.923 l/min for non-folding type

manually operated coconut dehusker.

It is observed that heart rate and oxygen consumption rate of operating folding type coconut

dehusker is less than non-folding type coconut dehusker. This may be due to comfortable posture

of working with folding type and suitable handle grip provided on folding type of coconut

dehusker. The energy cost of operation of dehusking operation was computed by multiplying the

oxygen consumed by subject during trail work with calorific value of oxygen as 20.80 kJ/l (Nag

et al. 1980), for all subject.

The mean values of heart rate and oxygen consumption of all subjects for manually operated

folding type coconut dehusker were 106.52 bpm and 0.865 l/min respectively. It was revealed

from Table 4 that the energy expenditure of all selected subjects varied from 3.22 to 6.45

kcal/min. The coconut dehusking operation was grade as very light when energy expenditure was

less than 2.5 kcal/min, light for those three subjects when energy expenditure varied from 2.5 to

5 kcal/min, moderate heavy when energy expenditure varied from 5 to 7.5 kcal/min, heavy when

energy expenditure varied from 7.5 to 10 kcal/min, very heavy when energy expenditure varied


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from 10 to 12.5 kcal/min and extremely heavy when energy expenditure was 12 kcal/min. The

coconut dehusking operation with folding type coconut dehusker is light grade. The average

value of energy expenditure for subjects operate non-folding type coconut dehusker is more than

the folding type coconut dehusker. The dehusking operation using folding type coconut dehusker

is easier than non-folding type coconut dehusker may due to its special feature of folding type

manually operated coconut dehusker.

Table 4 Energy cost of operation of all subjects while operating folding and non-folding

type coconut dehusker

Sub-

ject

Folding type Non-folding type

Energy

expenditur

e,

kJ/min

Energy

expenditure,

kcal/min

Energy

grade of

work

Energy

expenditure,

kJ/min

Energy

expenditure,

Kcal/min

Energy

grade of

work

1 19.31 4.59 Light 19.83 4.71 Light

2 27.144 6.45 Moderate

heavy 29.32 6.97

Moderate

heavy

3 15.66 3.72 Light 15.88 3.77 Light

4 16.39 3.90 Light 16.07 3.82 Light

5 14.40 3.42 Light 14.60 3.47 Light

6 13.50 3.21 Light 14.60 3.47 Light

7 17.74 4.22 Light 18.79 4.40 Light

8 13.57 3.22 Light 14.60 3.47 Light

9 19.836 4.72 Light 21.924 5.21 Moderate

heavy

10 22.96 5.46 Moderate

heavy 27.14 6.45

Moderate

heavy

Mean 18.05 4.29 Light 20.27 4.82 Light

The average value of worker HR from 6th to 15th minutes when dehusked by different subjects

was recorded, OCR of selected subject was recorded. The relative costs of workload during

operation were recorded (% of oxygen consumption rate to VO2max). The recorded value for


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folding and non-folding type dehuskers shown in Table 5.It was revealed from Table 5 that,

among all subjects was within the range of acceptable workload i.e. below 35 % of VO2 max.

The per cent values of VO2 max for folding and non-folding type coconut dehusker was in the

range of 7 to 11.85 % and of 7.37 to 13.38 % respectively. The mean value of per cent of VO2

max for folding and non-folding type coconut dehusker was 9.25 % 10.32% respectively. This

indicates that coconut dehusking by both manually operated coconut dehuskers was below the

acceptable workload and coconut dehusking operation is acceptable to all subject.

Table 5 Oxygen consumption rate as percent of VO2 max while operating folding type and

non folding type coconut dehuskers

Subjects


Per cent of VO2

max

Acceptable

workload (35 %

VO2 max)

Per cent of

VO2 max

Acceptable

workload (35 %

VO2 max)

1 9.36 < AWL 10.06 < AWL

2 11.85 < AWL 12.95 < AWL

3 8.46 < AWL 8.62 < AWL

4 7.79 < AWL 8.35 < AWL

5 7.03 < AWL 7.37 < AWL

6 8.38 < AWL 9.95 < AWL

7 9.74 < AWL 10.52 < AWL

8 8.50 < AWL 9.54 < AWL

9 10.09 < AWL 11.49 < AWL

10 11.35 < AWL 13.38 < AWL

Mean 9.255 < AWL 10.322 < AWL


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Table 6 Work pulse ( HR) of all selected subjects while operating folding and non-folding

type coconut dehusker

Subject Folding type Non-folding type

∆ HR, bpm LCP,40 bpm ∆ HR, Bpm LCP,40 bpm

1 31.14 < LCP 32.26 < LCP

2 25.57 < LCP 30.39 < LCP

3 26.72 < LCP 29.20 < LCP

4 32.82 < LCP 34.09 < LCP

5 23.17 < LCP 24.45 < LCP

6 24.86 < LCP 31.86 < LCP

7 34.05 < LCP 37.21 < LCP

8 24.86 < LCP 35 < LCP

9 25.27 < LCP 29.83 < LCP

10 21.28 < LCP 27.67 < LCP

Mean 26.97 < LCP 31.19 < LCP

From Table 6, it was observed that in the case of manually operated folding type coconut

dehusker, work pulse of the subjects varied from 63.6 to 84.4 bpm and HR varied from 21.28 to

34.05 bpm. The average value of HR was 26.97 bpm which was less than Limit of Continuous

Performance (LCP).In the case of manually operated non-folding type coconut dehusker, work

pulse of the subjects varied from 64.14 to 86.42 bpm and HR varied from 24.45 to 37.21 bpm.

The average value of HR was 31.19 bpm which was less than Limit of Continuous

Performance (LCP). This indicates that coconut dehusking with both folding and non-folding

type coconut dehusker can be operated continuously without any rest cycle.

The values of ODR and BPDS of subjects while operating folding and non-folding type

manually operated coconut dehusker are presented in Table 7.


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Table 7 Overall discomforts rating and Body part discomfort score of subjects for the

dehusking using folding and non-folding type manually operated coconut dehusker

Subject


ODR Scales BPDS

score ODR Scales

BPDS

score

1 3 Light discomfort 4.5 4 More than light

discomfort 4.5

2 2 No discomfort 7.5 3 Light discomfort 7.5

3 4 More than light

discomfort 6 2 No discomfort 7.5

4 4 More than light

discomfort 7.5 4

More than light

discomfort 6

5 3 Light discomfort 7.5 3 Light discomfort 6

6 3 Light discomfort 4.5 4 More than light

discomfort 7.5

7 4 More than light

discomfort 7.5 4

More than light

discomfort 7.5

8 2 No discomfort 7.5 2 No discomfort 6

9 4 More than light

discomfort 6 5

Moderate

discomfort 7.5

10 3 Light discomfort 6 4 More than light

discomfort 7.5

Mean 3 Light discomfort 6.45 4 More than light

discomfort 6.75

As shown in Table 7, it was observed that the coconut dehusking with manually operated folding

type coconut dehusker, the mean value of ODR was 3 which is light discomfort operation. The

coconut dehusking with manually operated non-folding type coconut dehusker, the mean value

of ODR was 4 which is more than light discomfort operation. For folding type coconut dehusker,

the mean value of BPDS of subjects was 6.45 and non-folding type was 6.75. The maximum

number of intensity levels of pain experienced coconut dehusker was 4 category. It is observed

that average BPDS score for coconut dehusking with folding and non-folding manual coconut

dehusker is marginal and can be considered at par. This may be due to similar type of operation

carried on both the coconut dehusker.


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CONCLUSIONS

The following conclusions are made from the study

1. The dehusking capacity and dehusking efficiency for folding and non type coconut

dehusker were observed as 58 nuts/h and 93.7 % and 52 nuts/h and 93 % respectively.

2. No damage to coconut shell dehusked were observed with both type.

3. The average recorded values of heart rate and predicted values of oxygen consumption of

subjects for folding type coconut dehusker were 106.4 bpm and 0.865 l/min respectively

and for non-folding type coconut dehsker were 110.9 bpm and 0.923 l/min respectively.

4. The average energy cost of operation of subjects while coconut dehusking with folding

and non-folding type coconut dehuskers were 4.29 and 4.82 Kcal/min respectively.

5. The average oxygen consumption rate as per cent VO2 max while operating folding and

non-folding type coconut dehusker were 9.255 and 10.322 l/min respectively. The

coconut dehusking operation is within acceptable limit for folding and non-folding type

coconut dehusker.

6. The average ∆HR value for subjects while coconut dehusking with folding and non-

folding type coconut dehuskers were 26.97 and 31.19 bpm respectively which was less

than limit of continuous performance (LCP).

7. The mean value of overall discomfort rating ( ODR) of subjects for coconut dehusking

operation with folding and non-folding type dehuskers was 3 (light discomfort ) and 4

(more than light discomfort) category respectively.

8. The average BPDS score while performing the coconut dehusking operation using

folding type and non-folding type manually operated coconut dehusker was 5.8 and 6.1

respectively.


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108.

Corlett, E. N. and Bishop, R.P., 1976.A technique for assessing postural discomfort Ergonomics,

19: 175-182.

Ghoshal, M.K. and Mohanty, S.K., 2011. Ergonomical study and performance evaluation of

different types of coconut dehuskers. International J. of Agric. Engg., 4(1):45-51.

Nwankwojike, B. N.; Onuba, O. and Ogbonna, U. 2012. Development of coconut dehusking

machine for rural small scale farm holders. Int. J. of Innovation Technology and

Creative Engg., (2)3.

Shirisha, D., K. Kathirvel and Manian, R. 2008. Development and Evaluation of Direct Paddy

Seeder for Assesing the Suitability to Rural Women. Agriculture Mechanization in

Asia, Africa and Latin America. 39(4):40-45.

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