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IPTEK The Journal for Technology and Science
Published by Institut Teknologi Sepuluh Nopember Surabaya
ISSN : 08534098     EISSN : 20882033     DOI : -
Core Subject : Science,
Computer Science & IT
IPTEK The Journal for Technology and Science (eISSN: 2088-2033; Print ISSN:0853-4098), is an academic journal on the issued related to natural science and technology. The journal initially published four issues every year, i.e. February, May, August, and November. From 2014, IPTEK the Journal for Technology and Science publish three times a year, they are in April, August and December in online version.
Arjuna Subject : -
Articles 6 Documents
 1 
Search results for , issue "Vol 20, No 4 (2009)" : 6 Documents clear
Detecting Springs in the Coastal Area of the Gunungsewu Karst Terrain, Yogyakarta Special Province, Indonesia, Analysis using Fractal Geometry Sari Bahagiarti Kusumayudha Sari Bahagiarti Kusumayudha
IPTEK The Journal for Technology and Science Vol 20, No 4 (2009)
Publisher : IPTEK, LPPM, Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j20882033.v20i4.86

Abstract

The Gunungsewu area is a karst terrain with water scarcity, located in the Yogyakarta Special Province, adjacent to the open sea of Indian Ocean in the South. Shorelines of the Gunungsewu southern parts show fractal geometry phenomenon, and there can be found some groundwater outlets discharging to the Indian Ocean. One of the coastal outlets exists at the Baron Beach.The amount of water discharge from this spring reaches 20,000 l/sec in wet season, and approximately 9000 in dry season. In order to find other potential coastal springs, shoreline of the south coast is divided into some segments. By applying fractal analysis utilizing air photo of 1 : 30,000 scale, the fractal dimension of every shore line segment is determined, and then the fractal dimension value is correlated to the existence of spring in the segment being analyzed. The results inform us that shoreline segments having fractal dimension (D) > 1.300 are potential for the occurrence of coastal springs.
Mixing Urea and Zeolite for Slow Release Fertilizer using Orbiting Screw Mixer Semuel Pati Senda; Renanto Handogo; Achmad Roesyadi; Wahono Sumaryono
IPTEK The Journal for Technology and Science Vol 20, No 4 (2009)
Publisher : IPTEK, LPPM, Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j20882033.v20i4.83

Abstract

Slow release fertilizer (SRF) of urea is prepared by using zeolite as the matrix. Mixing of urea and zeolite is carried out in orbiting screw mixer. The effects of rotation speed and orbital speed of the mixer and particle size on power consumption, homogeneity, mixing time and specific energy consumption are evaluated. The experimental results show that higher orbital speed gives higher power consumption. Power consumption is dominated by mixer rotation motion. Smaller particle size needs higher power for mixing process. Nitrogen mass fraction ranges from 0.45 to 0.49 when mixture reaches homogeneity. The mixing time required is about 5 – 12 minutes for particle size of >60 and >80 mesh and 7 – 14 minutes for particle size of >50 mesh. At constant orbit speed, the higher the screw rotation speed, the shorter time needed to reach mixture homogeneity. Specific energy consumption of mixing process increases with decreasing particle size. For the three particle size groups of >80 mesh, >60 mesh and >50 mesh, the lowest specific energy consumption is given by combination of orbital speed of 5 rpm and rotation speed of 50 rpm; while for particle size of >60 mesh and >80 mesh, it can obtained by combination of orbital speed of 5 rpm and rotation speed of 67,5 rpm and orbital speed 5 rpm and rotation speed 30 rpm, respectively. The lowest specific energy consumptions is gained by combination of orbital and rotation speeds of 5 and 50 rpm with particle size of >50 mesh.
Hydrodynamic Forces acting on Two Flexible Free-hanging Cantilevers in Tandem Configurations due to Cross-flows Prastianto, Prastianto
IPTEK The Journal for Technology and Science Vol 20, No 4 (2009)
Publisher : IPTEK, LPPM, Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j20882033.v20i4.85

Abstract

The experimental study has been performed on two flexible free-hanging circular cantilevers in tandem configurations subjected to uniform cross-flows. The experiment was intended to investigate the time-dependent forces characteristics acting on the cylinders due to VortexInduced Vibration (VIV) phenomenon. The tests cylinders have free bottom-end conditions and can freely oscillate. The motions of the cylinders are evaluated as a bidirectional motion, in-line and transverse to the flow. Each cylinder has a length-to-diameter ratio of 34.4 with a low mass ratio of about 1.24. Based on cylinder’s diameter and free-stream flow velocities, the Reynolds number varied from 10,800 to 37,800. For examining Wake Induced Vibration (WIV) on the induced forces characteristics, five different gaps between the cylinders were employed. New various findings indicated that the dynamics of the present two free-hanging cantilever cylinders in tandem configurations are unique and definitely different to those other tandem configurations of either, two stationary cylinders or a transverse-only motion downstream cylinder lies behind a stationary upstream one.
Advanced DVR with Zero-Sequence Voltage Component and Voltage Harmonic Elimination for Three-Phase Three-Wire Distribution Systems Margo P; Mauridhi Heri Purnomo; Mochamad Ashari; Zaenal P; Takashi Hiyama
IPTEK The Journal for Technology and Science Vol 20, No 4 (2009)
Publisher : IPTEK, LPPM, Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j20882033.v20i4.21

Abstract

Dynamic Voltage Restorer (DVR) is a power electronics device to protect sensitive load when voltage sag occurs. Commonly, sensitive loads are electronic-based devices which generate harmonics. The magnitude and phase of compensated voltage in DVR depend on grounding system and type of fault. If the system is floating, the zero sequence components do not appear on the load side. Meanwhile, in a neutral grounded system, voltage sag is extremely affected by zero sequence components. A blocking transformer is commonly installed in series with DVR to reduce the effect of zero sequence components. This paper proposes a new DVR control scheme that is capable of eliminating the blocking transformer and reducing harmonic distortion. The system uses fuzzy polar controller to replace the conventional PI or FL controller that is commonly used. By taking into account the zero sequence components in the controller design, the effects of zero sequence components can be compensated. Simulated results show the effectiveness of the proposed DVR controller
Hydrogen Sorption Behavior of the MgH2-Ni Prepared by Reactive Mechanical Alloying Mustanir, Mustanir; Jalil, Zulkarnain
IPTEK The Journal for Technology and Science Vol 20, No 4 (2009)
Publisher : IPTEK, LPPM, Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j20882033.v20i4.19

Abstract

Regarding the use of hydrogen in fuel cell for mobile or stationary applications, metal hydrides can offer a high hydrogen volume capacity and a safe alternative compared with liquid storage or with compressed gas. Among the metal hydrides, magnesium is considered as one of potential hydrogen storage materials because of its high capacity (7.6 wt%), lightweight and low cost. However, high work temperature would slow down kinetics reaction and harden activation process limit practical application of Mg-based hydrides as well. Recently, the high energy ball milling was successfully introduced to prepare hydrogen storage materials. In this work, MgH2 catalyzed with Ni nanoparticles was synthesized by planetary type ball milling under high pressure of hydrogen at 100 bar (10 MPa). As a result, small amount of Ni in nanometer scale acts as a suitable catalyst for kinetics improvement of MgH2 which could absorb 5.3 wt% of hydrogen within 5 minutes at 300ºC. It is obvious that small amount Ni (2 mol%) has much better catalyst than catalyst in nanoparticle size; and at the same time, it is allowed to reduce the milling process for short time (2 hours).
Sponge Diversity at Pecaron Bay Situbondo Based on Macroscopic and Microscopic Observation Setiawan, Edwin; Nurhayati, Awik Pudji Diah; Muzaki, Farid Kamal
IPTEK The Journal for Technology and Science Vol 20, No 4 (2009)
Publisher : IPTEK, LPPM, Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j20882033.v20i4.20

Abstract

The sponge species diversity recruited insitu macroscopic observation i.e, underwater photograph for sponges species diversity and spicula microscopic examination for sponges order group specimens have been conducted at Pecaron Bay Situbondo. Seventeen sponges species have been identified out of twenty species. The microscopic examination showed that the Diactinal oxea types were dominant in our 13 samples whereas the monoactinal oxea and style were represented only with 7 samples. Moreover, diactinal type of spicula can be used as an order group of sponges species at Pecaron bay Situbondo.

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