ANALISIS FREKUENSI PADA UJI TAK MERUSAK ULTRASONIK

In ultrasonic nondestructive testing an ultrasonic wave is usually radiated through a material by a transducer. If there is a flaw inside the material, reflected or diffracted waves caused by the interaction between the ultrasonic wave and the flaw, are received by the same or another transducer. The received signals must be processed in order to obtain information about the flaw characteristics. For the flaw which perpendicular to the beam wave, the flaw size can be determined by amplitude analysis, for example by using DGS (Distance Gain Scale) diagram. The oblique flaw can be characterized by time analysis such as Time of Flight Diffraction (TOFD) method. But if the flaw is small or there is a large enough noise, frequency analysis must be used. This paper deals with the two methods using frequency analysis, i.e. ultrasonic spectroscopy and split spectrum processing, to overcome the above problems

Pengukuran Aliran Udara Dalam Pipa Menggunakan Gelombang Ultrasonik Dengan Metoda Korelasi Silang

Flowmeter ultrasonik merupakan jenis flowmeter yang memanfaatkan gelombang ultrasonik dalam pengukurannya. Metoda yang umum digunakan adalah metoda waktu tempuh. Metoda ini memiliki prinsip pengukuran yang relatif mudah dibanding dengan metoda lainnya. Namun metoda ini kurang sesuai jika digunakan pada aliran fluida yang tidak laminar. Metoda korelasi silang dengan gelombang ultrasonik dapat digunakan untuk mengukur laju aliran fluida yang relatif bersih tetapi profil aliran yang tidak laminar.Pada makalah ini dibahas suatu studi eksperimen metoda korelasi silang untuk mengukur kecepatan aliran udara dalam suatu pipa. Dari hasil pengukuran dengan metoda waktu tempuh diperoleh kecepatan rata-rata aliran yang berbeda dengan yang diperoleh pada metoda korelasi silang. Hasil pengukuran metoda korelasi silang menunjukkan standar deviasi dan presisi yang relatif tinggi, Hal ini menunjukkan bahwa metoda korelasi silang memberikan hasil yang lebih baik pada kondisi aliran tidak laminar seperti aliran udara dalam pipa. Keywords : gelombang ultrasonik, metoda korelasi silang, waktu tunda, demodulasi, aliran turbule

Studi Pendahuluan Sistem Tomografi Listrik-Akustik untuk Mendeteksi Kanker Paru-paru

Penelitian ini bertujuan untuk mengkaji kemungkinan diterapkannya sistem tomografi listrik-akustik. Sistem tomografi ini dalam bekerjanya menggunakan injeksi pulsa arus listrik sehingga dihasilkan dua data sekaligus, yaitu sinyal akustik dan potensial listrik. Data sinyal akustik memiliki potensi untuk menghasilkan citra resolusi spasial tinggi, sedang data potensial listrik memiliki potensi untuk menghasilkan citra kontras tinggi. Metode yang dilakukan dalam penelitian ini adalah melakukan kajian studi tentang terpenuhinya kemungkinan syarat-syarat yang dibutuhkan. Untuk studi awal ini dilakukan studi simulasi untuk memperoleh data sinyal akustik yang kemudian dilakukan kajian analisis. Hasil dari penelitian ini menunjukkan bahwa sinyal akustik prospektif untuk digunakan dalam deteksi kanker paru karena kontrasnya nilai akustik organ paru dan jaringan kanker paru.

Simulasi Perambatan Gelombang Ultrasonik dengan Model Berkas Multi Gaussian dan Model Pengukuran Thompson Grey

Transduser ultrasonik adalah komponen untuk pembangkitan gelombang ultrasonik. Dalam aplikasi tertentu, pemilihan transduser yang tepat ditentukan oleh parameter yaitu, frekuensi, diameter, voltage drive, dan jarak  antar transduser. Salah satu cara yang efektif untuk menentukan parameter transduser yang sesuai adalah dengan melakukan simulasi perambatan gelombang ultrasonik yang dihasilkan transduser dengan berbagai variasi parameternya. Pada studi ini dilakukan kajian simulasi perambatan gelombang ultrasonik untuk transduser tercelup berbentuk piston dengan pendekatan model berkas gelombang multi-Gaussian dan model pengukuran Thompson-Gray. Simulasi menggunakan perangkat lunak yang dibuat berupa graphical user interface. Parameter-parameter transduser divariasikan untuk pengamatan pada berbagai kondisi. Hasil kajian simulasi divalidasi dengan hasil pengukuran eksperimen perambatan gelombang ultrasonik dari transduser tercelup berbentuk piston. Dari kajian, diperoleh perbedaan antara hasil simulasi dan eksperimen adalah 3.55% untuk nilai selisih tegangan keluaran dan 0.17% untuk nilai selisih waktu tempuh

Leak Detection Modeling and Simulation for Oil Pipeline with Artificial Intelligence Method

oai:ojs.pkp.sfu.ca:article/2Leak detection is always interesting research topic, where leak location and leak rate are two pipeline leaking parameters that should be determined accurately to overcome pipe leaking problems. In this research those two parameters are investigated by developing transmission pipeline model and the leak detection model which is developed using Artificial Neural Network. The mathematical approach needs actual leak data to train the leak detection model, however such data could not be obtained from oil fields. Therefore, for training purposes hypothetical data are developed using the transmission pipeline model, by applying various physical configuration of pipeline and applying oil properties correlations to estimate the value of oil density and viscosity. The various leak locations and leak rates are also represented in this model. The prediction of those two leak parameters will be completed until the total error is less than certain value of tolerance, or until iterations level is reached. To recognize the pattern, forward procedure is conducted. The application of this approach produces conclusion that for certain pipeline network configuration, the higher number of iterations will produce accurate result. The number of iterations depend on the leakage rate, the smaller leakage rate, the higher number of iterations are required. The accuracy of this approach is clearly determined by the quality of training data. Therefore, in the preparation of training data the results of pressure drop calculations should be validated by the real measurement of pressure drop along the pipeline. For the accuracy purposes, there are possibility to change the pressure drop and fluid properties correlations, to get the better results. The results of this research are expected to give real contribution for giving an early detection of oil-spill in oil fields

Leak Detection Modeling and Simulation for Oil Pipeline with Artificial Intelligence Method

Leak detection is always interesting research topic, where leak location and leak rate are two pipeline leaking parameters that should be determined accurately to overcome pipe leaking problems. In this research those two parameters are investigated by developing transmission pipeline model and the leak detection model which is developed using Artificial Neural Network. The mathematical approach needs actual leak data to train the leak detection model, however such data could not be obtained from oil fields. Therefore, for training purposes hypothetical data are developed using the transmission pipeline model, by applying various physical configuration of pipeline and applying oil properties correlations to estimate the value of oil density and viscosity. The various leak locations and leak rates are also represented in this model. The prediction of those two leak parameters will be completed until the total error is less than certain value of tolerance, or until iterations level is reached. To recognize the pattern, forward procedure is conducted. The application of this approach produces conclusion that for certain pipeline network configuration, the higher number of iterations will produce accurate result. The number of iterations depend on the leakage rate, the smaller leakage rate, the higher number of iterations are required. The accuracy of this approach is clearly determined by the quality of training data. Therefore, in the preparation of training data the results of pressure drop calculations should be validated by the real measurement of pressure drop along the pipeline. For the accuracy purposes, there are possibility to change the pressure drop and fluid properties correlations, to get the better results. The results of this research are expected to give real contribution for giving an early detection of oil-spill in oil fields

METODA ULTRASONIK UNTUK MENENTUKAN ARAH KRISTAL TUNGGAL BERSTRUKTUR KUBIK

Single crystal direction can be determined by x-ray diffraction. The determination of this crystal direction can also be carried out by using ultrasonic method. In this method the ultrasonic wave velocity propagating through the crystal is measured. From this velocity measurement then the crystal direction can be determined. This paper deals with the results of a research about the direction determination of cubic single crystal using ultrasonic wave. There are two methods used, namely graphical method and computer method. These two methods used the same data, i.e. velocity data for all possible direction that has been calculated based on the wave and elasticity theory. In the ï¬rst method, the data are stored as several graphics whereas in the second method they are stored as database in a computer program. These two methods have shown the same results in aluminum for crystal directions [311], [331], [661], [631] and [611] where the computer method can be carried out quicker than the graphical method

The Influence of Position of Durian in Determination of Ripeness of Durian Non-Destrucyively by Ultrasonic Wave

The study was conducted to assess the influence of durian 's position toward transmission properties of ultrasonic wave for determination of the fruit ripeness using non-destructiive technique. Three ripe and unripe durian were used to assess transmittance wave that was passed the durian. The measurement was conducted at 3 peak and valley positions and it was repeated 20 times. The result showed that position durian 's inJluenccad thetransmissions of ultrasonic wave. Mo mzJ a (attenuation) values can be used as indicator for durian ripeness. Ripe durian tends to have highera value than unripe durian

The Measurement of Sucrose Content of Sugar Cane Using Ultrasonic Waves

The measurement of sucrose content of sugar cane is usually carried out by using polarimeter and Brix Wager scale. These two apparatus are operated manually so that the accuracy of the measurement results is depended on the operator skill. To overcome this problem we have developed an alternative method that can measure the sucrose content more quickly and accurately than the conventional methods. This new method was carried out by using ultrasonic waves whose velocity depends on the sucrose content. Firstly, the electronic apparatus used was calibrated with 37 samples of sugar cane with various sucrose content from 4.46 % to 7.29 %. The result of this calibration was an empirical equation between the ultrasonic wave velocity V and the sucrose content R, i.e. R = 2.65 V2 - 11,95 V + 17,65 where R in % and V in km/s. Then this equation was stored as database in a computer program that will be used to calculate the sucrose content. Finally, this sucrose content measurement system was tested by using 30 samples of sugar cane. The maximum error of the measurement result was 6.4 %