Electrospinning is a simple and flexible process in continuous fiber fabrication. We investigate the effect of applied voltage on morphology and phases of poly(vinylidene difluoride) nanofibers obtained using the electrospinning technique. Quantitative and qualitative analyses were performed employing multiple characterizations such as Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). The fiber diameter, affected by the spinning jet's deformation, has non-uniform distribution at low voltages (10-16 kV) and is uniform at higher voltages (20 kV). Fiber uniformity developed due to the increased tension, which shrank the Taylor cone. The highest electroactive fraction (F EA ) of phases was obtained for the smallest diameter fiber with an average diameter of 110 nm at an applied voltage of 20 kV. FTIR spectroscopy and XRD results indicate that the electric field raises the amount of F EA phase to 74% at the present working parameters. HRTEM analysis revealed that the crystallites are very small, with ⊍-phase showing a size of around 10 nm and ⊎-phase is only of nanometric scale. Results also show that the c-axis of ⊍-phase crystallites had a preferred orientation along the fiber axis. On the other hand, the c-axis of ⊎-phase had a preferred orientation perpendicular to the fiber axis, implying that the direction of crystal growth for the ⊍-phase and ⊎-phase was different.

Makalah ini membahas tentang desain sistem kendali motor DC brushless menggunakan microcontroller ATMega 16 untuk diimplementasikan pada independent 4-Wheel drives pada platform Mobil Robot LIPI versi 2 (REV-11). Sistem kendali yang dibuat terdiri dari 2 bagian yaitu modul kendali motor DC brushless dan kendali supervisor yang berfungsi untuk mengoordinasi perintah ke modul-modul kendali motor. Untuk mengendalikan platform REV-11, kendali supervisory mengirimkan data referensi berupa kecepatan dan arah pada modul kendali motor sebagai referensi untuk mengendalikan kecepatan dan arah dari masing-masing aktuator pada platform REV-11. Dari hasil pengujian disimpulkan bahwa sistem kendali yang didesain sudah mampu berfungsi dengan baik untuk mengkoordinasi dan mengendalikan kecepatan dan arah gerak motor aktuator platform REV-11.

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Critical speed rotor phenomenon characteristics at gas turbine generator is evaluated using finite element method. In this study, the critical speed is evaluated based on the over speed of 4500 rpm. The critical speed of the rotor is investigated in the Campbell diagram, which shows the relationship between natural frequency and rotational velocity of the system Dynamic characteristic in this paper simulated with ANSYS rotor dynamic software. The Finite Element simulation results will be known forms of vibration at each critical speed. Finally the results od simulation can be a reference for dynamic analysis and optimized the design of rotor generator.

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In recent years, paper-based analytical devices gained more attention for development of low-cost point-of-care diagnostic tools in many fields, such as environmental testing, point of care diagnosis, and food analysis. In the present study, we introduce a new paper substrate (Xuan paper) and compare to commercial filter paper (whatman) with hydrophobic materials called polydimethylsiloxane (PDMS). The xuan paper can be used for paper-based microfluidics analytical devices (μPAD) and that flow rate is reliant on many factors affecting fluid flow inside the channels. The screen-printing method was used to concocted hydrophobic channels by patterning hydrophobic materials onto paper substrate with the patterned channels reaching a minimum width of 0.2 mm and maximum 5 mm. The fabricated channels were tested by using water with different paper types and different channel widths. The experimental results were compared with commercially available filter paper (11 and 21 µm pore size). The results of this study are raw xuan paper (0.15 mm of thickness) is similar trend with filter paper (0.21 mm of thickness) about 43 mm distance in 140 second and it is higher than three other papers. However, jinghe paper (0.13 mm of thickness) and cotton xuan paper (0.10 mm of thickness) shows the distance of water about 10 mm and 4 mm, respectively in 140 second because of their fiber orientation and water being absorbed by it. Therefore, xuan paper was a good candidate in applied for µPAD application.

Ocean Current Energy Conversion System (OCECS) is a promising green energy resource in this globe. The Thermohaline circulation data indicates that the Wallacea region has the potential of ocean current energy resources. This paper is aimed to propose research and development of OCECSs to be implemented in the Wallacea region. Firstly, four types of green energy conversion systems extracted from ocean are reviewed. Their advantages and disadvantages are discussed. Secondly, the potential of OCECS in the Wallacea region is described. Third, many types of turbines used for OCECS are reviewed and the turbine type for OCECS is selected to be implemented in the Wallacea region. Fourth, control strategy is proposed.From the work reported in this paper it is concluded that it is appropriate to implement OCECSs using axial flow water turbines in the Wallacea region, and that to maximize energy conversion variable speed control approach is selected together with control of mechanism to move the turbine vertically as well as to rotate the turbine in yaw direction.

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