The Effect of Pre-swirl on the Discharge Coefficient of Rotating Axial Orifices

The characteristic of the flow through a set of rotating orifices for particular conditions is quantified in terms of a discharge coefficient which is the ratio of the actual flow divided by the flow for the ideal case. In the present study the pre-swirl was created by having Inlet Guide Vanes (IGVs) at the inlet of the rotating orifices. Pre-swirl changes the angle of attack to the orifice, and thus affects the incidence angle and the discharge coefficient. Pre-swirl improves the discharge coefficient in inclined orifices since it allows the incidence angle to reach zero at a much lower rotational speed than when there is no pre-swirl

Status Penelitian Cendana Di Propinsi Nusa Tenggara Timur

Cendana (Santalum album L.) adalah hasil hutan yang tergolong sangat penting dari Propinsi Nusa Tenggara Timur (NTT), karena merupakan spesies endemik yang terbaik di dunia dan mempunyai nilai ekonomi tinggi. Dewasa ini populasinya sudah semakin menurun. Oleh sebab itu dalam pemanfaatan perlu segera diikuti upaya pelestarian. Untuk mewujudkan upaya tersebut sebagaimana yang diharapkan, dukungan teknologi sangat diperlukan. Balai Penelitian Kehutanan (BPK) Kupang yang berkedudukan di daerah inti produksi cendana telah berupaya secara sungguh-sungguh untuk menyediakan teknologi yang dibutuhkan lewat kegiatan penelitian. Paket-paket teknologi hasil penelitian cendana yang telah dihasilkan dan sudah dapat diujicobakan untuk pengembangannya di lapangan antara lain teknik pembuatan Hutan Tanaman dengan menggunakan sistem tumpangsari, pengelolaan tegakan alam lewat permudaan tunas akar yaitu dengan pemotongan akar lateral pohon induk cendana dan teknik penggalian tunggak akar yang dilaksanakan saat penebangan, penentuan target tebangan tahunan yang berdasarkan data jumlah pohon masak tebang, kandungan teras dan daur/umur pohon cendana. Dalam rangkamendapatkan benih cendana dengan kualitas dan kuantitas yang memadai dewasa ini upaya pemuliaan pohon cendana telah mulai dilakukan. Kegiatan yang sedang berjalan antara lain pemilihan calon pohon plus, uji keturunan, uji provenan, teknik kultur jaringan,penunjukan tegakan benih dan pembangunan kebun benih. Adapun hasil sementara kegiatan ini telah dilakukan penunjukan pohon plus sebanyak 175 pohon beserta uji keturunanya di Pulau Timor, pembangunan kebun benih seluas 4 ha, kultur jaringan cendana seperti pengembangan eksplan, pengakaran dan pembentukan kalus, dari kultur jaringan, uji provenansi dan penunjukan tegakan benih. Sebagian besar penelitian ini berlangsung dalam jangka panjang. Kebijakan pengelolaan cendana di NTT yang diatur oleh PERDA No.16 tahun 1986 masih rendah memberikan kontribusi bagi upaya pelestarian cendana secara berkelanjutan. Oleh karena itu aturan ini perlu disempurnakan agar dapat menguntungkan masyarakat dan pemerintah agar mampu mendorong partisipasi masyarakat dalam upaya pelestarian cendana. Paket-paket teknologi yang dihasilkan BPK Kupang yang sudah siap untuk dikembangkan perlu diangkat menjadi kebijakan dalam rangka membantu pelestarian cendana

Single-, Dual- and Triple-band Frequency Reconfigurable Antenna

The paper presents a frequency reconfigurable slot dipole antenna. The antenna is capable of being switched between single-band, dual-band or triple-band operation. The antenna incorporates three pairs of pin-diodes which are located within the dipole arms. The antenna was designed to operate at 2.4 GHz, 3.5 GHz and 5.2 GHz using the aid of CST Microwave Studio. The average measured gains are 1.54, 2.92 and 1.89 dBi for low, mid and high band respectively. A prototype was then constructed in order to verify the performance of the device. A good level of agreement was observed between simulation and measurement

Calibration and accuracy assessment of Leica ScanStation C10 terrestrial laser scanner

Requirement of high accuracy data in surveying applications has made calibration procedure a standard routine for all surveying instruments. This is due to the assumption that all observed data are impaired with errors. Thus, this routine is also applicable to terrestrial laser scanner (TLS) to make it available for surveying purposes. There are two calibration approaches: (1) component, and (2) system calibration. With the intention to specifically identify the errors and accuracy of the Leica ScanStation C10 scanner, this study investigates component calibration. Three components of calibration were performed to identify the constant, scale error, accuracy of angular measurement and the effect of angular resolution for distance measurement. The first calibration has been processed using closed least square solutions and has yielded the values of constant (1.2 mm) and scale error (1.000008879). Using variance ratio test (F-Test), angles observation (horizontal and vertical) for Leica C10 scanner and Leica TM5100A theodolite have shown significance difference. This is because the accuracy of both sensors are not similar and these differences are 0.01 and 0.0075º for horizontal and vertical measurements, respectively. Investigation on the resolution setting for Leica C10 scanner has highlighted the drawback of the tilt-and-turn target. Using the highest resolution, Leica Cyclone software only able to recognize the tilt-and-turn target up to 10 m distance compare to 200 m for the black and white target

Wide to multiband elliptical monopole reconfigurable antenna for multimode systems applications

Wideband-multiband reconfigurable elliptical monopole antenna is investigated in this paper. By having conventional elliptical monopole antenna, wideband operating frequency is obtained. With the combination of dual pairs of slotted arms and a band-pass filter on the ground plane of the elliptical monopole, multiband is achieved. Dual-band operating frequencies at 1.6 GHz and 2.6 GHz while wideband operates from 3.35 GHz to 9 GHz. Therefore, wide range of wireless communication systems is obtained from the proposed antenna to support the multiband mode (i.e. GPS and LTE) and UWB systems. Frequency reconfigurable is achieved by controlling the switches integrated on the antenna structure. Simulated results of reflection coefficient, radiation patterns and gain performance are presented. The proposed antenna design is suitable candidate for different wireless communication applications

Implementing Virtual Pair Programming in E-Learning Environment

Programming subjects are one of the core and important subjects that should be taken by students majoring in information system or computing. The problem of teaching and learning of programming has been widely reported in literatures. Many attempts have been made to solve this problems and this has led to many new approaches in teaching and learning of programming. One of the approach that has been proposed is the use of pair-programming, which is one of the practice of eXtreme Programming (XP). The advent of e-learning has given birth to the idea of Virtual Pair Programming (VPP). This paper describes how asynchronous mode of collaboration using VPP could be implemented for e-learning learners to learn programming

The Effect of Shielding Gas Flow Rate on Fiber Laser Welding of Boron Steel

During laser welding process, the ionized metal vapor from keyhole surrounding by molten metal mixes with the shielding gas and forms a plasma plume over the molten pool. The small amount of plasma plume is needed to react with molten pool by enhancing the absorption of laser energy thus increase the penetration. However, high amount of plasma will absorb the beam energy and this could decreases the penetration depth. The small wavelength of laser beam such as fiber laser, reported has less influence to plasma plume compared to bigger wavelength such as CO2 laser. However, even though using small wavelength laser, the laser beam with welding speed below 17mm/s had to go through the plasma plume over the molten pool. The suppression of plasma plume is highly influenced by shielding gas setup and flow rate. In this study, the effect of shielding gas flow rate (Argon) on CW and PW mode on low power fiber laser welding of Boron steel (22MnB5) was investigated. The observation of welding surface, width and depth were carried out. The width and depth pattern of CW and PW were slightly different. The range of 10-20L/min shows the widest width and 15L/min shows the deepest penetration for both welding mode

Application of Large-Scale 3D Non-Orthogonal Boundary Fitted Sediment Transport Model and Small-Scale Approach for Offshore Structure in Cimanuk Delta North Java Sea

The morphology of the Cimanuk Delta at the North Java Sea has changed rapidly over the last two decades. The annual sediment deposition is about two million cubic meters (Yuanita and Tingsanchali, [1]). The large-scale ocean hydrodynamics and sediment transport model MuSed3D (Muin, [2]) was applied to the North Java Sea to simulate suspended sediment transport at the study site. A potential offshore structure was positioned at approximately 30 km from the Cimanuk Delta. The result of the large-scale model was calibrated using observation data and Landsat satellite image interpretation. The agreement between the modeling results and the observations was excellent. It was found that the critical shear stresses for erosion and deposition were 0.1 Pa and 0.05 Pa respectively. An empirical formula was further utilized to assess the local scouring at the potential offshore structure site in a small-scale domain and under extreme conditions

Comparison of deposition methods of ZnO thin film on flexible substrate

This paper reports the effect of the different deposition methods towards the ZnO nanostructure crystal quality and film thickness on the polyimide substrate. The ZnO film has been deposited by using the spray pyrolysis technique, sol-gel and RF Sputtering. Different methods give a different nanostructure of the ZnO thin film. Sol gel methods, results of nanoflowers ZnO thin film with the thickness of thin film is 600nm. It also produces the best of the piezoelectric effect in term of electrical performance, which is 5.0 V and 12 MHz of frequency which is higher than other frequency obtained by spray pyrolysis and RF sputtering