Sandra Sandra
Agriculture Engineering, Brawijaya University, Malang, Indonesia

Published : 40 Documents
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Aplikasi Jaringan Syaraf Tiruan untuk Pendugaan Mutu Mangga Segar Secara Non-Destruktif Sandra, Sandra
Jurnal Teknologi Pertanian Vol 6, No 1 (2005)
Publisher : Fakultas Teknologi Pertanian Universitas Brawijaya

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Abstract

The objective of this study was to estimate grade of mango with artificial neural network.  There are three grade of mango: grade I, grade II and grade III. Each grade consists of 40 samples. The Artificial Neural Network consists of three model; first model: 3 input, second model: 5 input and third model: 7 input.  Each of models consists of three outputs with 1000, 2500, and 5000 iteration, and 3, 5, and 7 hidden layers. The result of this study show that the accuracy of artificial neural network in grade of mango: (1) the first model 60% - 100%;  (2) the second model 90% and (3) the third model 90 %. The conclusion of this study is the artificial neural network can predict the grade of mango and the best model is the third model.   Keywords: Mango, grade, artificial neural network
Study of the zones of gold mineralization in Siliwanga village, Lore Peore district, Poso regency, using geomagnetic method Nurinaya, Nurinaya; Efendi, Rustan; Sandra, Sandra
Gravitasi Vol 14, No 1 (2015)
Publisher : Gravitasi

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Abstract

Talise is an area with a fairly high construction activities at the present time. The condition of the buildings in this area is susceptible to damage. This problem is mainly caused by constructing many buildings without considering the structure of subsurface. The purpose of this study is to determine the classification and types of rock below the surface through the analysis of shear wave velocity to a depth of 30 m (Vs30) instudy area. The method used in this research wasRefraction Mikrotremor (Remi) that records a shear wave propagationhappening below the surface. Data processing was performed using Surface Wave Analysis Wizard and WaveEq (Surface Wave Analysis) programs.The interpretation of 6 tracks shows that the greater depth obtained, the greater value range of shear wave velocity happened. The results of this study werethe form of classification and subsurface rock types with 4 different study sites, namelyAbadi field, Jabal Nur field, Mapolda Sulteng, and School of Model Terpadu Madani. The former study site is classified astype E (soft soil), while the others are classified as type D (stiff soil).   Keywords:Refraction mikrotremor (ReMi), shear wave velocity, Vs30, classification of rock.
Analysis of shear wave velocity to a depth of 30 m (Vs30) inTalise Village using Refraction Mikrotremor method Nurrahmi, Nurrahmi; Efendi, Rustan; Sandra, Sandra
Gravitasi Vol 14, No 1 (2015)
Publisher : Gravitasi

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Abstract

Talise is an area with a fairly high construction activities at the present time. The condition of the buildings in this area is susceptible to damage. This problem is mainly caused by constructing many buildings without considering the structure of subsurface. The purpose of this study is to determine the classification and types of rock below the surface through the analysis of shear wave velocity to a depth of 30 m (Vs30) instudy area. The method used in this research wasRefraction Mikrotremor (Remi) that records a shear wave propagationhappening below the surface. Data processing was performed using Surface Wave Analysis Wizard and WaveEq (Surface Wave Analysis) programs.The interpretation of 6 tracks shows that the greater depth obtained, the greater value range of shear wave velocity happened. The results of this study werethe form of classification and subsurface rock types with 4 different study sites, namelyAbadi field, Jabal Nur field, Mapolda Sulteng, and School of Model Terpadu Madani. The former study site is classified astype E (soft soil), while the others are classified as type D (stiff soil).   Keywords:Refraction mikrotremor (ReMi), shear wave velocity, Vs30, classification of rock.
The identification of iron ore distribution in Pancuma village, Tojo district using geoelectric resistivity Method Yuniarti, Tiara; Musa, Moh. Dahlan Th.; Sandra, Sandra
Gravitasi Vol 14, No 1 (2015)
Publisher : Gravitasi

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Abstract

The identification of iron ore distribution under surface in Pancuma village, Tojo district, using the geoelectric resistivity of schlumberger configuration has been conducted. Results of the data processing at 6 estimation points in study area using Progress software indicate that the estimated layer type contained iron ore which had the resistivity values of 50.5 Ωm–80.8Ωm with the maximum layer thickness of 50.1 m and the minimum layer thickness of 0.7 m. The distribution of the estimated layers has thicker layer in southern part and thinner layer in northern part in study area. Key Words: Geoelectric, Resistivity, Progress software, Iron ore.
Identifying the subsurface layer structure and the temperature distribution of geothermal areas in Mantikole village Suryadi, Yantri; Efendi, Rustan; Sandra, Sandra
Gravitasi Vol 14, No 1 (2015)
Publisher : Gravitasi

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Abstract

Research on identifying the subsurface layer structure and the temperaturedistribution of geothermal areas in Mantikolevillage. Dolodistrict, Sigiregency has been conducted. Measurements were performed on3 tracks around geothermal sources by using the geoelectric resistivity of wenner configuration that was subsequently processed using EarthImager2D software. Based on the results of dataprocessing, the subsurface layer structures in study area were surface water, clay, and igneous rock of granite with resistivity values ranging between 75 Ωm-1585 Ωm.Subsequently, the obtainedresistivity values were converted to a temperature distribution using anequation that is derived from Archie formula and further modelled usingRockwork software. Considering this temperature distribution, it is known that the temperature values ranged between 38oC-57oC with the highest temperature at the second track. Keywords: Geolistrik resistivity, geothermal, temperature distribution.
Estimation of the elasticity characteristics of the subsurface rocks using shear wave Amalia, fatimah; Efendi, Rustan; Sandra, Sandra
Gravitasi Vol 14, No 1 (2015)
Publisher : Gravitasi

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Abstract

The research using the method of refraction microtremor (REMI) has been carried out in the village of Salua, District of Kulawi. Seismic method of refraction microtremor (REMI) is an effective and efficient method for determining the shear wave velocity (shear wave) each bedding soil. The purpose of this study was to determine the subsurface structure based on the propagation speed of shear waves and to estimate the elasticity characteristics of the subsurface rocks. Data processing is divided into two phases. The first stage is done by using two programs that use the Surface Wave Analysis Wizard program and WaveEq (Surface Wave Analysis) program. The second stage determines the shear modulus of rock. From the data processing of the 6 lines can be seen that the subsurface structure is dominated by dry sand with shear wave velocity range of 80 m/s with a shear modulus range of 10,24-70,56 N/m2 and by soil with shear wave velocity in the range of 120 m/s with a shear modulus from 38,16-108 N/m2, and also by clay with shear wave velocity in the range of 405 m/s with a shear modulus 377,25 N/m2. Keywords: Microtremor refraction (ReMi), shear wave velocity, shear modulus
Determining the structure of Rock areas land sliding USING SEISMIC MIKROTREMOR in the Village Enu Sindue, Donggala District Nausil, Syamsuddin; Efendi, Rustan; Sandra, Sandra
Gravitasi Vol 14, No 1 (2015)
Publisher : Gravitasi

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Abstract

The research using refraction of micro-tremor has been conducted in the Village of Enu,Districtof Sindue, Regency of Donggala. Refraction seismic method of micro-tremor is an effective and efficient method for determining the shear wave velocity of rock bedding. This study aims to determine the structure of the soft soil layers that have the potential landslides as well as determining the value of the depth of each layer. Data taking of used 24 channel geophones which spaced 3 meter between geophones and 3 tracks. Data processing was done in 2 stages: first stage using Surface Wave Analysis Wizard program to get phase velocity relation as a function frequency and the second stage using WaveEq program to obtain the shear wave velocity (Vs) as a function of depth (m). Interpretation performed to infert the structure of geological layers below the surface based on the value in the medium speed of shear wave propagation velocity. The interpretation results of shear wave velocity for 1-st track is located on the third layer with depth of12 m and Vs = 105 m/s, for 2-nd track is located also on third layer with a depth of 9 m and Vs = 80 m/s, and for the 3-rd track is laid on 2-nd layer with a depth of 8 m and Vs = 105 m/s. The soft rocks that acts as a sliding plane is granite and claywhich covered limestone with Vs = 80 m/s-105 m/s and the depth of 8 m-12 m. Kata kunci: micro-tremor refraction, shear wave, bedrock, landslide.  
Identifikasi Sebaran Panasbumi Menggunakan Metode Geolistrik Hambatan Jenis di Desa Wani Tiga, Kabupaten Donggala Arif, Arif; Sandra, Sandra; Musa, Dahlan Th.
Online Journal of Natural Science FMIPA Vol 4, No 3 (2015): Volume 4 Number 3 (December 2015)
Publisher : Online Journal of Natural Science FMIPA

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.2012/

Abstract

Telah dilakukan penelitian untuk untuk mengidentifikasi sebaran panasbumi yang terdapat di Desa Wani Tiga, Kecamatan Tanantovea Kabupaten Donggala Propinsi Sulawesi Tengah. Pengukuran dilakukan dengan metode Automatic Array Scanning (AAS) menggunakan Konfigurasi Wenner-Schlumberger. Pengolahan data menggunakan program inversi Earthmarger2D. Lapisan dengan Nilai resistivitas yang berkisar antara ±1 Ωm-10 Ωm ditunjukkan dengan warna biru diduga merupakan pasir lempung, dimana lapisan ini diduga sebagai lapisan yang berisikan airpanas (hydrothermal). Sebaran air panas menebal ke arah utara pada kedalaman ± 8 m hingga kedalaman yang tidak terdeteksi.
Analisis Kontras Spekel menggunakan LSI (Laser Speckel Imaging) untuk Mendeteksi Formalin pada Tomat (Lycopersicum Esculentum Mill) Fitrya, Neneng; Sandra, Sandra; Harmadi, Harmadi
Jurnal Fisika dan Aplikasinya Vol 9, No 2 (2013)
Publisher : Jurnal Fisika dan Aplikasinya

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (463.853 KB) | DOI: 10.12962/j24604682.v9i2.845

Abstract

Telah dilakukan pendeteksian formalin pada tomat dengan menggunakan metode LSI (Laser Spekcle Imaging). Sistem LSI terdiri dari tiga komponen utama yaitu laser sebagai sumber cahaya, sampel dan sebuah detektor cahaya. Pecitraan pola spekel dengan metode LSI mendeteksi perubahan intensitas laser spekel yang dihamburkan oleh sampel dan dianalisis sebagai kontras spekel. Pola spekel dianalisis menggunakan software imageJ dan diperoleh karakterisasi histogram distribusi intensitas gray level. Perubahan pola spekel tomat dapat digunakan untuk membedakan tomat yang berformalin dengan yang tidak berformalin. Dilakukan penyinaran terhadap tomat sebelum dan sesudah direndam larutan formalin dengan variasi konsentrasi 0,001%, 0,005%, 0,01%, 0,05%, dan variasi waktu perendaman yaitu selama 15 menit dan perendaman selama 30 menit. Secara umum korelasi kontras spekel dengan formalin pada tomat, menunjukkan bahwa formalin terdeteksi dengan perubahan kontras spekel pada tomat. Semakin tinggi konsentrasi formalin dan waktu perendaman nilai kontras spekel semakin kecil.
Estimasi Gradien Temperatur Menggunakan Metode Geomagnet Pada Daerah Panasbumi Di Desa Sapoo Kecamatan Kulawi Nurarafah, Nurarafah; Efendi, Rustan; Sandra, Sandra
Natural Science: Journal of Science and Technology Vol 5, No 3 (2016): Volume 5 Number 3 (December 2016)
Publisher : Univ. Tadulako

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Abstract

Penelitian menggunakan analisis spektrum pada data geomagnet telah dilakukan di Lapangan Panasbumi Sapoo, Kabupaten Sigi. Penelitian  ini bertujuan untuk memperoleh estimasi gradien temperatur Curie pada daerah panasbumi tersebut. Tahapan pengukuran anomali magnetik meliputi; akuisisi data lapangan, melakukan koreksi IGRF dan koreksi variasi harian, dan kemudian membuat peta kontur anomali. Berdasarkan peta kontur anomali medan magnet hasil interpretasi kualitatif, diperoleh nilai anomali magnet tinggi sebesar (340 n), dan anomali magnet rendah sebesar( 20 nT).  Teknik yang digunakan adalah teknik analisis spektrum untuk memperoleh kedalaman dan untuk mengetahui gradien temperatur dan aliran panasbumi di daerah penelitian. Nilai rata-rata kedalaman yang diperoleh yaitu untuk kedalaman atas, kedalaman tengah, dan kedalaman basal adalah berturut-turut1.267 m, 2.161 m, dan 3.054,5 m. Nilai gradien temperatur masing-masing lintasan yaitu lintasan A, lintasan B, lintasan C, lintasan D adalah berturut-turut 0,19748042 , 0,21577381 , 18709677 dan 0,16604638