This paper presents a study of controlling magnetic levitation object using conventional sliding mode control (CSMC) and sliding mode control (SMC) with gain-scheduled. SMC with gain-scheduled aims to improve the robustness of the control system from disturbance. The CSMC simulation results show that output can follow the set point if there is no interference, but if the disturbance happens then there is overshoot and undershoot of 0.034 mm and 0.07 mm for disturbance 10 * sin( ) and 20 * sin( ). Then SMC with gain-scheduled shows excellent performance because the output can follow the reference even if it got disturbance of 10 * sin( ) and 20 * sin( ).

Electrospray as an alternative method to fabricate thin film is studied. High voltage is required by the electrospray system. The requirement of high voltage is different for various liquid depending on the surface tension property. Ethanol was used to resemble the solvent used in thin film deposition. From the experimental work, jetting performance did not occur despite of the high applied voltage which is around 1 KV. In this work, numerical calculation is carried out to find the reason behind of unsuccessful jetting at 1 KV applied voltage. The percentage of Rayleigh limit is around 0.4. Electrospray performance at walking distance 5 mm using ethanol is predicted to be stable when the applied high voltage is approximately 1.1 KV. The numerical investigation indicates that the jetting performance will occur if the applied voltage is more than 1.1 KV.

Intisari — Bencana alam seperti gerakan tanah atau longsor dapat terjadi pada berbagai skala dan kecepatan. Untuk meminimalkan kerugian akibat bencana tersebut maka dilakukan usaha mengenal tanda-tanda yang mengawali gerakan tanah, atau disebut sebagai mitigasi. Penelitian ini dilakukan untuk merancang wireless sensor network yang mampu mengidentifikasi bencana longsor. Node sensor terdiri dari: sensor getaran, sensor kemiringan lahan, sensor pergeseran lahan, kontroler, dan modul transmisi data. Node-node sensor ini ditanam pada daerah yang rawan longsor dan saling berkomunikasi antara node satu dengan lainnya. Data-data berupa getaran, kemiringan lahan, dan status selalu ditransmisikan ke base station sistem peringatan dini longsor secara realtime. Ketika bencana longsor akan segera terjadi node sensor diharapkan mampu mendeteksi dan mengaktifkan alarm yang ada pada node sensor serta mengirimkan tanda bahaya ke base station. Kata Kunci — longsor, wireless sensor network, node sensor, mikrokontroler   Abstrak — Natural disasters such as land movements or landslides can occur at various scales and speeds. To minimize damages due to the disaster, an effort is made to recognize the signs that initiate soil movements or referred to as mitigation. This research was conducted to design a wireless sensor network that can identify landslides. Sensor nodes consist of vibration sensor, slope sensor, land shift sensor, controller, and data transmission module. These sensor nodes are planted in areas inclined to landslides and communicate with each other between nodes. The data vibration, the slope of the land, and status are always transmitted to the base station of the landslide early warning system in real time. When an landslide will occur soon the sensor node is expected to be able to detect and activate the alarm on the sensor node and send an signal to the base station. Keyword — landslides, wireless sensor networks, sensor nodes, microcontrollers

Bidang pemetaan lahan skala kecil menggunakan UAV (Unmanned Aerial Vehicle) sebagai sarana  pemetaan. UAV memerlukan komunikasi tanpa kabel (wireless) dengan jarak yang jauh dan stabil. Untuk itu dibutuhkan sebuah antena dengan pola pancaran yang jauh dan penguatan (gain) yang tinggi. Penelitian ini menggunakan Antena Yagi karena memiliki pola pancaran yang terarah (directional)  tetapi memilki kelemahan yaitu, antena yagi harus diarahkan secara pointing untuk menjaga komunikasi antara antena dan UAV. Berdasarkan hasil perhitungan dan simulasi antena yagi dengan frekuensi 433 MHz, diperoleh penguatan (gain) sebesar 14,2 dBi. Rancangan antenna yagi dibuat menggunakan Almunium dan tembaga berbentuk pipa. Dari hasil pengujian jarak komunikasi didapat jarak jangkauan ± 5 km. Pengujian dilakukan dengan memasangkan antena yagi ke modul receiver telemetri 433 MHz, kemudian modul transceiver dipasang di pesawat tanpa awak (UAV) yang diterbangkan.

Electrospray system had attracted attention of many researchers. It is due to easy to yield uniform thin film and possible for thin film mass production. The important parameters of electrospray process for getting uniform thin film are electric field distribution, surface substrate treatment and solvent properties. In this work, we observed electric field distribution on meniscus. Numerical work has carried out on this work. The material on meniscus used zinc oxide liquid properties. Voltage and walking distance between nozzle and substrate are the most important parameter to adjust electric field distribution. The decreasing walking distance with constant voltage yields increasing electric field distribution on meniscus. On vice versa, the increasing walking distance yields decreasing electric field distribution on meniscus. Increasing and decreasing voltage yields increasing and decreasing electric field distribution on meniscus, respectively.