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STUDI DIFRAKSI GELOMBANG MENGGUNAKAN PERSAMAAN HIPERBOLA
Full text linkThe deformation of wave is the change of wave characteristics that occurs when a wave propa-
gates shoreward. One form of the deformation of wave is diffracted wave. Wave diffraction occurs
when a wave is blocked by a barrier which is a breakwater or an island. As a result, the wave will
turn around the tip of the barrier and heading into a sheltered area behind it. In this event, the en -
ergy transfer occurs in the perpendicular direction to the protected area. The phenomenon of
wave diffraction is an important thing to consider in the harbor and breakwater design. To deter-
mine the wave diffraction pattern caused by obstacles or coastal structures, wave propagation
simulation has been carried out with mathematical or numerical models for several scenarios. In
this study, two-dimensional wave simulation software using hyperbolic equations has been used to
model wave propagation. The result obtained from this study is the diffraction coefficient whose
value which is approximately equal to the ones suggested by the Shore Protection Manual (SPM,
1984). Changes in the pattern of the wave occur after the wave propagates through a single or
double breakwater. This study also investigated the changes in the wave height and the amount of
dominant wave period due to the influence of the breakwater. Both events indicate the occurence
of phenomenon of diffraction
Daftar Isi Jurnal Rekayasa Edisi Agustus 2015
No full textDaftar Isi Jurnal Rekayasa Edisi Agustus 201
Model Stokastik Curah Hujan Harian dari Beberapa Stasiun Curah Hujan di Way Jepara
Full text linkThis research was conducted to study and know the characteristics of periodic and stochastic
models of daily rainfall in the Way Jepara. This study used secondary data, namely daily rainfall
data with a data length of 13 years (1997-2013) from the station Braja Arjosari, Braja Indah, and
Jepara Lama.
In this study , daily rainfall data is processed into the form of time series before it was trans-
formed into the spectrum of rainfall using the program FFT (Fast Fourier Transform). One year
of daily rainfall data periodicity, only used 512 rainfall data are periodic. Spectrum rainfall pro-
duce data series stochastic rainfall is assumed as the difference (error) between the actual rainfall
data with periodic rainfall models. Based on data from the series of stochastic, the stochastic com-
ponent is calculated using the approach of autoregressive models. Stochastic model generated us-
ing the least squares method (least square method) or autoregressive model of order three. Vali-
dation of stochastic series between the measured data and the model is done by calculating the
correlation coefficient.
From the research, the correlation coefficient obtained an average of three stations of the
daily rainfall. Value of the average correlation coefficient ( R ) between the data with a model pe-
riodic rainfall amounted to 0.97305, the data series is stochastic and stochastic models of
0.99150, and between data and periodic stochastic models are at 0.99963. From the results, it can
be concluded that the periodic stochastic models of rainfall Way Jepara region gives very accurate
results and the approach significantly
MODEL PERIODIK DAN STOKASTIK DATA PASANG SURUT JAM-JMAN DARI STASIUN MENENG
Full text linkThe aim of this study are to compare periodic and stochastic models generated by using FFT fre-
quencies with periodic and stochastic models generated by using astronomic frequencies. Fourier
series are used to simulated periodic model, and autoregressive method is employed to simulate
stochastic model. In this study, 253 dominant FFT frequencies and 9 astronomic frequencies are
used as constituent frequencies to simulate periodic models. 512 hours of data are used for the
model.
Results of this study present that the periodic and stochastic models using FFT frequencies give
more accurate results than periodic and stochastic models using the astronomic frequencies
Studi Kekuatan Batu Bata Pasca Pembakaran Dengan Menggunakan Bahan Additive Serbuk Gergaji Kayu
Full text linkThe Increasing construction in Indonesia and the number of population which is increasing every
year must be supported by better economy growth. Thus, the construction materials will continue
to increase to support the needs of infrastructure construction. To support the development and
growth, then brick as a construction material will be needed. One of the method that can be used
to improve the quality of the soil material is to use mixing ingredients (additives) such as sawdust
to facilitate the combustion process and as a pore-forming on bricks. Based on the explanation
above , it is necessary to do an objective study of making bricks, so that sawdust can be used as an
right mix alternative in the manufacture of bricks, in the hope of sawdust waste is not wasted, but
it can add power to brick and can produce bricks with good quality.
Soil samples were tested in this study is a fine-grained soil from the Yosomulyo village, East Metro
District, Metro City. Variations in the levels of the mixture used is 5%, 10%, 15% and 20%, with a
curing time of 14 days as well with post-combustion treatment on the brick. Based on the results
of physical testing of the original soil, USCS classified the soil samples as fine-grained soil and
included in the ML group.
This study used additive materials, such as wood sawdust mixture, on the mixture of 5% level, red
brick experienced an escalation compared to bricks that are not mixed with additive materials. At
the levels of a mixture of 10%, 15% and 20%, bricks decreased, both in terms of compressive
strength and quality of bricks. So, in a mixture of 10%, 15% and 20%, the brick is not
recommended for use as a building material because it does not fit to the requirements of SNI 15-
2094-2000 and water absorption rate is only 15% the level of compliance with the standards
between 14% to with 18%
Cover Belakang Jurnal Rekayasa Edisi April 2015
No full textCover Belakang Jurnal Rekayasa Edisi April 201
Sampul muka Jurnal Rekayasa Edisi Agustus 2014
No full textSampul muka Jurnal Rekayasa Edisi Agustus 201
Daftar Isi Jurnal Rekayasa Edisi Desember 2014
No full textDaftar Isi Jurnal Rekayasa Edisi Desember 201
OPTIMIZATION OF RICE FIELD CROPPING PATTERN IN WAY KETIBUNG IRRIGATION AREA AT SOUTH LAMPUNG DISTRICT
Full text linkLand use changing in Way Ketibung Irrigation Area from rice field cropping to rubber and palm
oil planting were one of causes to decline rice field production at its irrigation area. The changing
of land use were caused by lack of water availability . Therefore, it is necessary efforts to optimize
irrigation area in order to increase rice production.
Based on cropping schedule which used by Way Ketibung Irrigation Area the farmer had define
cropping season, rainy cropping season (rendeng, MT I) and dry cropping season (gadu, MT II).
The 1 st class of rainy cropping season was started on 1 st week of September and on 1 st week of Jan-
uary to the 1 st class of dry cropping season. Whereas, the 2 nd class of rainy season began on 2 nd
week of September and on 2 nd week of January to the 2 nd class of dry season. Cropping pattern
which based on its cropping schedule that the farmers have done was not suitable, because only a
few one could apply the schedule to crop rice field. It is due to the water availability could not
serve the amount of water to its cropping pattern.
Field observation and hydrologic analysis using suitable approach methods produced the opti-
mized cropping pattern that approximated by reliable discharge has 80 % probability in occurs
(Q 80 ) and Net Farm Requirement (NFR). The optimized cropping pattern of Way Ketibung Irriga-
tion Area defines the cropping season. The 1 st class of rainy cropping season begins on 2 nd Decem-
ber and 2 nd April to 1 st class of dry cropping season. Whereas, The 2 nd class of rainy cropping sea-
son begins on 1 st January and 1 st May to 2 st class of dry cropping season. Water balance analysis
describe surplus and deficit of water, therefore could be generated cropping pattern rotation as;
The rainy cropping season (MT I) : 1 st class begin on 2 nd week of December with 821 hectares (100
%), 2 nd class begin on 1 st week of January with 612 hectares (100 %). The dry cropping season
(MT II) : 1 st class begin on 2 nd week of April with 50 % of 821 hectares, 2 nd class begin on 1 st week
of May with 50 % of 612 hectares