9 research outputs found
Mechanical behaviour of Sugar palm (Arenga pinnata) fibres
ArticleThe tensile strength of Sugar palm (
Arenga pinnata
) fibres was examined. Fibre
samples were prepared and tested up to the point of rupture with a deformation rate of
0.05 min
-
1
. The tensile device (Labortech, MPTest 5.050, Czech Republic) were used to
determine the tensile force. The aim of the paper was
to describe a mechanical behaviour of Sugar
palm (
Arenga pinnata
) fibres. Measured values can be used as a basis for further research on the
application of Sugar palm fibres
Linear pressing of coconut copra meal (Cocos nucifera L.) under different temperatures
ArticlePressing of vegetable oils plays an important role in the food processing. This study
described the compression behaviour of copra (Cocos nucifera L.) using the universal
compression testing machine and vessel diameter of 60 mm with a plunger. The influence of heat
treatment on oil recovery efficiency and specific mechanical energy were determined.
Compression tests at the rate of 1 mm s
−1 under five different temperatures 20, 40, 60, 80 and
100 °C were performed. The measuring range of force was between 0 kN and 50 kN. It has been
found that the amount of obtained oil increased and specific mechanical energy decreased with
increased temperature. Measured data were analysed by computer software Mathcad 14
(MathCAD 14, PTC Software, Needham, MA, USA). Mathematical model describing the
mechanical behaviour of bulk copra under compression loading was represented
Factors influencing use of fuelwood and its environmental impacts in Tapanuli Utara regency, North Sumatra
ArticleDeforestation and forest degradation, after burning of fossil fuels, is considered as the
second leading cause of anthropogenic greenhouse emissions (accounting for over 17% of
global carbon dioxide emissions) and has become an important issue concerning
climate change
mitigation. The provision of wood energy is generally thought to be a major contributor to
forest loss. In Indonesia, more than half of the rainforest there, the third
-
largest swath in the
world, has been felled in just a few years. Further
more, permission has been granted to convert
the majority of what remains into palm or acacia plantations. The logging and burning of forests
to clear land for cultivation has made Indonesia one of the largest emitters of greenhouse gases.
Therefore, the o
bjective of this study was to assess the current level and influencing factors of
the use of fuelwood among the rural population as well as the consequent environmental
impacts in the target area in North Sumatra. The questionnaire survey using randomly se
lected
households (n
=
196) was administered in Tapanuli Utara regency from July to August 2014;
followed by several field visits from August to September 2016. Obtained data were analysed
with descriptive statistics and cross tabulation. The results indic
ate that fuelwood is a significant
source of energy in the target area. For 31% of respondents it is the major energy source and for
64% it is a supplementary source. The high rate of use of wood as fuel corresponds to the poor
financial situation of respo
ndents and the easy accessibility of wood, but only from the
surrounding area (own garden or adjacent land). Wood resources are often very distant (on
average over 1,000 metres) as a consequence of high deforestation. This study reveals that there
is a non
-
sustainable trend of forest conversion resulting in high land degradation in Tapanuli
Utara regency
Extraction of oil from rapeseed using duo screw press
ArticleThis study was focused on the analysis of optimize the pressing process of rapeseeds
(
B
rassica napus L.)
using screw press. For pressing of oil a screw press Farmer 20
–
duo (Farmer
20, Farmet a.s., Ceska Skalice, Czech republic) was used. The screw rotation speed 10, 20, 30,
40, 55 and 65
rpm was used. Oil recovery efficiency and specific mechanical energy were
decreased when the seed material troughput was increased. It has been found that the optimal
operation point for screw press Farmer 20
–
duo was at 20
kg
h
-
1
rapeseed throughput. The
specific mechanical energy at the optimal operation point was 0.61
kWh
kg
oil
-
1
Maximum oil
recovery efficiency 82.6% was found at the lowest screw speed
Modelling of hot-air and vacuum drying of persimmon fruit (Diospyros kaki) using computational intelligence methods
The study evaluated the feasibility of applying computational intelligence methods as
a non-destructive technique in describing the drying behaviour of persimmon fruit using vacuum
drying (VD) and hot-air-drying (HAD) methods and to compare the results with thin layer
mathematical models. Drying temperatures were 50, 60 and 70 °C. Kinetic models were developed
using semi-theoretical thin layer models and computational intelligence methods: multi-layer
feed-forward artificial neural network (ANN) and support vector regression (SVR). The statistical
indicators of coefficient of determination (R2
) and root mean square error (RMSE) were used to
assess the suitability of the models. The thin-layer mathematical models namely page and
logarithmic accurately described the drying kinetics of persimmon slices with the highest R2 of
0.9999 and lowest RMSE of 0.0031. ANN showed R2
and RMSE values of 1.0000 and 0.0003,
while SVR showed R2 of 0.9999 and RMSE of 0.0004. The validation results indicated good
agreement between the predicted values obtained from the computational intelligence methods
and the experimental moisture ratio data. Based on the study results, computational intelligence
methods can reliably be used to describe the drying process of persimmon fruit
Mathematical Models Describing the Creep and Stress Relaxation Behavior of False Banana’s Fiber (Ensete Ventricosum)
Viscoelastic behavior is an important parameter for the use of natural fibers in technical applications. Mathematical models to describe the relaxation and creep behavior of Ensete fibers were investigated. The aim of the experiment was to describe the short-term creep and relaxation behavior under tension loading. The fibers of Ensete ventricosum, originally from Ethiopian region Hawasa, were used in this experiment. Moisture content Mc = 8.54 ± 0.42% (d. b.) of the samples were determined. The viscoelastic tests were performed at six load levels (15, 30, 45, 60, 75, and 90% of yarn breaking load). Measured values of the relaxation and creep behavior were fitted to the mathematical models. The results show that generalized Maxwell model and Kelvin-Voight model with two branches can be used to describe relaxation and creep behavior of Ensete fibers