The Global Navigation Satellite System (GNSS), nowadays, is to be an important tool for determining positions and times on the real-time and post-processing applications. This study aims to assess the performance of the single frequency L1-GPS using low cost receivers. The performance will be evaluated by comparing with the geodetic L1+L2 GPS receiver to positioning performance. The low cost receivers used were Ublox NEO-M8T and Allystar HD9100. While, the dual frequency GPS TOPCON was used as reference receiver. The results show, RTK mode can improve the accuracy compare with single positioning up to centimetres. In this experiment, the Allystar HD9100 gives a better result than Ublox Neo M8T. However, the result discrepancies may be caused by the simple antenna splitter.

AbstrakSurvei hidro-oceanografi dilakukan untuk mengetahui karakteristik fisik dari suatu perairan. Salah satu kegiatan yang termasuk dalam survei hidro-oceanografi adalah penentuan kedalaman dan pencitraan bentuk topografi dasar laut. Pada umumnya, survei tersebut dilakukan dengan menggunakan wahana apung (kapal) yang relatif besar yang minimal dapat menampung surveyor dan pengemudi kapal. Wahana apung konvensional tersebut memiliki keterbatasan dalam bermanuver, terutama di daerah perairan yang dangkal dan sempit. Keterbatasan dalam mobilisasi, juga menjadi kendala ketika wahana apung konvensional akan digunakan untuk survei di area perairan pedalaman (sungai, waduk, dam, bekas galian tambang). Geomarine 1 merupakan solusi alternatif untuk melakukan survei hidro-oseanografi di daerah perairan dimana penggunaan wahana apung konvensional tidak dapat digunakan secara efektif. Geomarine 1 merupakan wahana apung tanpa awak (Unmanned Surface Vehicle) yang memiliki sistem mandiri (autonomous). Wahana apung tanpa awak ini dilengkapi dengan sensor anti tabrakan (collision avoidance) dan fungsi kembali ke titik awal (home return) apabila survei sudah selesai dilakukan ataupun pada saat baterai akan habis. Sensor survei hidro-oceanografi yang terdapat pada wahana ini merupakan kombinasi sensor akustik dan optik. Sensor akustik digunakan untuk penentuan kedalaman dan pencitraan topografi dasar laut, sedangkan sensor optik digunakan untuk perekaman kondisi fisik perairan secara visual.

With the increasingly strict requirements of the ship classification bureau for permissible noise limits to allow passengers and crew to be more comfortable and secure a technical assessment is required to address the characteristics of the noise. A noise beyond the standard allowed in the vessel can be a problem to the ship operators. This noise problem will greatly affects the crews' comfort and passengers. One method to reduce the noise on a ship is to use sound insulation. This paper describes the method for determining the absorption coefficient α and the transmission loss (TL) through an acoustic test of a concrete insulation in the laboratory. The test was conducted by using the method of impedance tube where a speciment response measured by a microphone. In general, the properties of this insulation material remains as the main base material which is concrete. it has been found that the transmission loss value (TL) is in the range of 10 - 50 dB whereas for the base material the concrete is around 22 - 49 dB but the absorption coefficient α of the specimen material is much higher than the material of the base material especially in high frequency, which ranges from 0.15 to 0.97, whereas for concrete base materials have absorbent coefficient α ranges from 0.01 to 0.02.

AbstrakPembangunan di Surabaya sangatlah cepat. Terdapat 105 gedung bertingkat yang pada perawatan kacanya menggunakan tenaga pembersih konvensional. Hal ini menyebabkan banyaknya kecelakaan kerja yang diakibatkan oleh ketinggian gedung. Untuk mengatasi masalah ini, salah satu solusi yang bisa dilakukan adalah contohnya mengganti tenaga pembersih konvensional dengan mesin, seperti robot pembersih kaca. Robot pembersih kaca menggunakan cairan dan kain pembersih atau bisa disebut claner. Penggunaan cleaner dicatat untuk mendapatkan data hasil penggunaan cairan pembersih. Proses ini biasa kita sebut monitoring. Proses monitoring akan terbantu jika prosesnya dilakukan secara otomatis. Sistem monitoring ini menggunakan water level sensor sebagai pendeteksi berapa tinggi level cairan permbersih pada robot pembersih kaca. Monitoring level cairan pembersih kaca ditampilkan pada android. Display pada android menggunakan modul Bluetooth HC-05. Pada pengujian sensor didapatkan bahwa rata-rata koreksi sebesar 0.065556, dan nilai ketidakpastian alat ukur ±0.120015678 dengan tingkat kepercayaan 95%. AbstractDevelopment in surabaya were very fast. There were 105 buildings which in the care of glass used exertion conventional cleaners. It caused many accidents caused by the height of building. To solve this problem, there was one of solution that can be done for example to replace the conventional energy with cleaner engine, like glass cleaning robot. Glass cleaning robot usually used cleaning fluid with cleaning cloth or cleaner. Consumption of cleaner fluid was noted to get the result of used cleaner fluid. Monitoring would be helpful If process of monitoring is be done automatically. This monitoring system used water level of detection sensors as how high the level of liquids on glass cleaner robot. Monitoring the level of glass cleaner robot is displayed on android. Display used bluetooth HC-05 modul. Testing result was got that average amounting were 0.065556 correction, and value of measuring uncertainty were ±0.120015678 with levels of trust 95 %.

The variation of wind speed causes the electric power generated by the turbine also varies. To obtain maximum power, the rotor speed of wind turbines must be optimally rated. The rotor speed can be controlled by manipulating the torque from the generator; this method is called Torque Control. In that case, a DC-DC converter is needed as the control actuator. In this study, a buck converter-based supervisory control design was performed on the Horizontal-axis wind turbines (HAWT). Supervisory control is composed of two control loops arranged in cascade, and there is a formula algorithm as the supervisory level. The primary loop uses proportional control mode with a proportional gain of 0.3, whereas in the secondary loop using proportional-integral control mode with a proportional gain of 5.2 and an integral gain of 0.1. The Supervisory control has been implemented successfully and resulted in an average increase in turbine power of 4.1 % at 5 m s–1 and 10.58 % at 6 m s–1 and 11.65 % at 7 m s–1, compared to wind turbine systems without speed control.