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Jurnal Rekayasa
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Articles 246 Documents
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Analisa Karakteristik Hujan di Kota Bandar Lampung Margaretta Welly
Rekayasa : Jurnal Ilmiah Fakultas Teknik Universitas Lampung Vol 19, No 3 (2015): Edisi Desember 2015
Publisher : UNIVERSITAS LAMPUNG

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Abstract

Knowledge of the characteristics of rainfall causes floods and droughts is an important thing. This research intends to investigate the characteristics of rainfall in the city of Bandar Lampung in or- der to predict and anticipate events of drought and flood in Bandar Lampung. The data used in this study is the annual rainfall data obtained from four rainfall stations in Bandar Lampung from 1987 until 2006. The stations that are: Pahoman Station, Sukarame, Sumur Putri, and Kemiling (Sumber Rejo). The results showed that the pattern and trend of the respective data from each of the stations the rain is not too different from each other. Most of the stations showed decreased dy - namically on rainfall. Although this decline did not occur in the rest of the station, but in general decline is clearly visible when the trend was taken fourth. A dry year, the year in which the annual precipitation totals less than 90% of the average annual rainfall, dominated after the year 2000. Most of the rainfall in the year El Nino is below the average annual precipitation. Near Pahoman, there have been five times the annual rainfall is below average at the time of El Nino (1991, 1992, 1993, 2002, 2004). Near Sukarame, there has been four times the annual rainfall is below aver- age at the time of El Nino (1991, 1997, 2002, 2004). At the Sumur Putri station, there has been four times the annual rainfall is below average at the time of El Nino (1991, 1993, 2002, and 2004). Near Kemiling, there has been four times the annual rainfall is below average at the time of El Nino (1991, 1992, 1997, 2002). This suggests the possibility of EL Nino events are associ- ated with a decrease in rainfall in each station.
Sampul Muka Jurnal Rekayasa Edisi April 2014 Zakaria, Ahmad
Rekayasa : Jurnal Ilmiah Fakultas Teknik Universitas Lampung Vol 18, No 1 (2014): Edisi April 2014
Publisher : UNIVERSITAS LAMPUNG

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Sampul Muka Jurnal Rekayasa Edisi April 2014
PEMODELAN PERIODIK DAN STOKASTIK CURAH HUJAN KOTA BANDAR LAMPUNG Ahmad Zakaria; Kartini Susilowati; Rasimin Rasimin
Rekayasa : Jurnal Ilmiah Fakultas Teknik Universitas Lampung Vol 18, No 1 (2014): Edisi April 2014
Publisher : UNIVERSITAS LAMPUNG

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This research aims to study the periodic and stochastic modeling of daily precipitation data series. The study was carried out using data of daily rainfall data with a length of 13 years (1987 – 2000) from Pahoman, Sumur Putri, and Sumber Rejo rainfall stations. The rainfall series used is as- sumed to be free from the influence of the trend. This research use how to convert data into time series sepektrum rain precipitation using program FFT (Fast Fourier Transform). Periodicity of daily rainfall data is presented using a periodic component 512. Stochastic rainfall series of rain- fall data is assumed as the difference (error) between the rainfall data with periodic rainfall model using 512 components. Based on the data series on stochastic stochastic component, calculated using the approach of the autoregressive model. Stochastic models presented by using a autore- gressive model of order two. The results of this research is the value of the correlation coefficient of the average precipitation three stations. For this study, the average correlation coefficient (R) between data and model of 0,9719 is periodic, between data and stochastic model is 0,9974, and between the data and the model with stochastic is 0,9974. From these results it can be concluded that periodic stochastic model of the rainfall of the Bandar Lampung City that processing model using 512-series compo- nents, presented a very significant approach.
Daftar Isi Jurnal Rekayasa Edisi Agustus 2014 Ahmad Zakaria
Rekayasa : Jurnal Ilmiah Fakultas Teknik Universitas Lampung Vol 18, No 2 (2014): Edisi Agustus 2014
Publisher : UNIVERSITAS LAMPUNG

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Daftar Isi Jurnal Rekayasa Edisi Agustus 2014
MODEL FISIK BANGUNAN PENGAMAN PILAR JEMBATAN AKIBAT ALIRAN DEBRIS Anwar Anwar
Rekayasa : Jurnal Ilmiah Fakultas Teknik Universitas Lampung Vol 18, No 2 (2014): Edisi Agustus 2014
Publisher : UNIVERSITAS LAMPUNG

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Debris flow generally occurs in rivers in mountainous areas. This flows is a very dangerous and destructive. This happens because the debris flow has a high speed and carry a mixture of sediment and other materials. Of infrastructure is built on rivers area flow pattern makes the need for special handling to maintain the protected structure with a substantial investment. This study focuses on the modeling and observation influence debris flow on bridge piers with three (3) conditions: unprotected bridge piers, using gabion protection, and bored pile protection on the model. By using a discharge of 1.54 liters/sec on a scale model of the maximum scours depth is obtained that occurred on bridge piers unprotected condition, that is equal to 1.7 cm and the minimum scours occurs in conditions of safety piers the bored pile is equal to 1.48 cm. The maximum scours volume occurs in the downstream bridge using gabion protected, amounting to 400 cm 2 , while the minimum volume of sediment scours occurs by using a safety bored pile 257.5 cm 3 . By the using protected piers bored pile more effective to resist scours due to debris flows. This is due to the construction of bored pile does not impede the flows that occurs so that the effect scours will reach a point of equilibrium.
Daftar Isi Jurnal Rekayasa Edisi Desember 2014 Ahmad Zakaria
Rekayasa : Jurnal Ilmiah Fakultas Teknik Universitas Lampung Vol 18, No 3 (2014): Edisi Desember 2014
Publisher : UNIVERSITAS LAMPUNG

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Daftar Isi Jurnal Rekayasa Edisi Desember 2014
MODEL PERIODIK DAN STOKASTIK DATA PASANG SURUT JAM-JMAN DARI STASIUN MENENG Ahmad Zakaria
Rekayasa : Jurnal Ilmiah Fakultas Teknik Universitas Lampung Vol 18, No 3 (2014): Edisi Desember 2014
Publisher : UNIVERSITAS LAMPUNG

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The 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.
OPTIMASI WADUK REGULATING DAM DI KABUPATEN PRINGSEWU, PROVINSI LAMPUNG Dharmawan Setioko; Gatot Eko Susilo; Ahmad Zakaria
Rekayasa : Jurnal Ilmiah Fakultas Teknik Universitas Lampung Vol 19, No 1 (2015): Edisi April 2015
Publisher : UNIVERSITAS LAMPUNG

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Abstract

Argoguruh Weir is the biggest irrigation weir in Lampung Province. This hydraulic structure was developed in 1935, crossing Way Sekampung River and serving Sekampung Irrigation Area which is about 67,000 ha. This weir is supplied by water from Batutegi Dam and baseflow of the upper Way Sekampung basin. Excessive water in Argoguruh Weir is passing by and flowing to the sea. Due to this condition, the government plan to build a dam between Batutegi Dam and Argoguruh Weir. This research aims to carry out a simulation of water balance in the Regulating Dam in order to find the best operational pattern for the dam. The Objective function of the simulation is water ele- vation of reservoir with probability more than 80%. The constrain of the simulation is that water elevation of the reservoir has to be higher than the water elevation of reservoir dead storage that is +102.30 m. Discharge data used in the simulation is daily discharge data of Argoguruh Weir from the year 2005 to the year 2013. The simulation is operated in 15-days time basis. Results of the simulation indicate that the objective function of the simulation is found in elevation +116.07 m with probability of 80.09%. On that condition, water from the reservoir is utilised for PDAM Pringsewu water supply and for the water supply for 242.90 ha new irrigation area. The lowest water elevation in this condition is +111.86 m. This water elevation is much more higher than the one of reservoir dead storage.
MODEL PERIODIK DAN STOKASTIK DATA PASANG SURUT JAM-JAMAN DARI PELABUHAN PANJANG Ahmad Zakaria
Rekayasa : Jurnal Ilmiah Fakultas Teknik Universitas Lampung Vol 19, No 1 (2015): Edisi April 2015
Publisher : UNIVERSITAS LAMPUNG

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Abstract

The aim of this study are intended to compare periodic and stochastic tide models generated by using FFT frequencies and astronomic frequencies. The Fourier series are used to simulated peri- odic model, and the autoregressive method is employed to simulate stochastic model. 253 domi- nant 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 the FFT frequencies give more accurate results than periodic and stochastic models by using the astronomic frequen - cies.
Model Stokastik Curah Hujan Harian dari Beberapa Stasiun Curah Hujan di Way Jepara Ahmad Zakaria; Margaretta Welly; Mirnanda Cambodia
Rekayasa : Jurnal Ilmiah Fakultas Teknik Universitas Lampung Vol 19, No 2 (2015): Edisi Agustus 2015
Publisher : UNIVERSITAS LAMPUNG

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Abstract

This 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.

Page 18 of 25 | Total Record : 246

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