Sepuluh Nopember Institute of Technology
Surabaya, Indonesia
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Zainuri M.,Sepuluh Nopember Institute of Technology
IOP Conference Series: Materials Science and Engineering | Year: 2017

This study has been investigated the effect of hematite as microwave absorbing materials (RAM) on X-Band frequency ranges. Hematite was succesfully processed by coprecipitation method and calcined at 500 °C for 5 hour. It was synthesized from natural iron stones from Tanah Laut, South Kalimantan, Indonesia. The products were characterized by X-ray diffraxtion (XRD), conductivity measurement, Vibrating Sample Magnetometer (VSM), and Vector Network Analyzer (VNA). The result was shown that hematite has conductivity value on (2.5-3).10-7 S/cm and be included as dielectric materials. The hysterisis curve was shown that hematite was a super paramagnetic materials. The product was mixed on paint with procentage 10% of total weight and coated on steel grade AH36 with spray methods. Then, the maximum of reflection loss on x - band's frequency range (8,2-12,4) GHz was -7 dB on frequency of 10.5 GHz. It mean that almost 50% electromagnetic energy was absorbed by hematite. © Published under licence by IOP Publishing Ltd.

Sumarno,Sepuluh Nopember Institute of Technology
AIP Conference Proceedings | Year: 2017

Ketoprofen was a poorly soluble which anti-inflammatory, analgesic and antipyretic drug, solubility of which can be enchanced by form complexation with β-cyclodextrin. Besides that, the inclusion complex reduces the incidence of gastrointestinal side effect of drug. The aims of this research are to study the effect of H2O concentration in the supercritical carbondioxide and operation condition in the formation of ketoprofen-β-Cyclodextrin inclusion complex. This research was began by dissolved H2O in supercritical CO2 at 40°C and various saturation pressures. Then, dissolved H2O contacted with (1:5 w/w) ketoprofen-β-Cyclodextrin mixture at 50°C and various operation pressures. It called saturation process. Saturation was done for ±2 hours with agitation process and continued by decompression process. The products were characterized by drug Release, Differential Scanning Calorimetry (DCS) dan Scanning Electron Microscopy (SEM) analyses. The percentage from this work were 76,82%-89,99% for inclusion complexes. The percentage drug release of ketoprofen were 82,83%-88,36% on various inclusion pressure and various inclusion period. © 2017 Author(s).

Herdeiro C.,University of Aveiro | Kunz J.,University of Oldenburg | Radu E.,University of Aveiro | Subagyo B.,Sepuluh Nopember Institute of Technology
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2015

We construct rotating boson stars and Myers–Perry black holes with scalar hair (MPBHsSH) as fully non-linear solutions of five dimensional Einstein gravity minimally coupled to a complex, massive scalar field. The MPBHsSH are, in general, regular on and outside the horizon, asymptotically flat, and possess angular momentum in a single rotation plane. They are supported by rotation and have no static limit. Such hairy BHs may be thought of as bound states of boson stars and singly spinning, vacuum MPBHs and inherit properties of both these building blocks. When the horizon area shrinks to zero, the solutions reduce to (in a single plane) rotating boson stars; but the extremal limit also yields a zero area horizon, as for singly spinning MPBHs. Similarly to the case of equal angular momenta, and in contrast to Kerr black holes with scalar hair, singly spinning MPBHsSH are disconnected from the vacuum black holes, due to a mass gap. We observe that for the general case, with two unequal angular momenta, the equilibrium condition for the existence of MPBHsSH is w=m1Ω1+m2Ω2, where Ωi are the horizon angular velocities in the two independent rotation planes and w,mi, i=1,2, are the scalar field's frequency and azimuthal harmonic indices. © 2015 The Authors

Hisyam I.,Sepuluh Nopember Institute of Technology
AIP Conference Proceedings | Year: 2017

This paper describes the application of revenue management in government services to ensure sufficient domestic supply of food in Indonesia. The use of this approach means that the government runs a specific effort to radically be able to solve the core problem. The resources for domestic food production are owned by more than 26 million families of farmers and more than 4 thousands agricultural companies. To achieve the expected quantity of foodstuff supplies, a special effort needs to take into account the profit for producers in allocating the resources at an appropriate level. With revenue management, the price of foodstuff to ensure adequate domestic supply to a certain level of productivity can be known. In this context, the price may be reduced if there is an increase in productivity. For this purpose, the supply curve and the demand-supply equilibrium of foodstuff have been modeled and specific government programs to increase productivity were formulated. One important finding here is that the macroeconomic policy of the government can be integrated to a microeconomic policy of foodstuff producers for one or more certain objectives. © 2017 Author(s).

Baihaqi I.,Sepuluh Nopember Institute of Technology | Sohal A.S.,Monash University
Production Planning and Control | Year: 2013

Information sharing has been cited as one of the major means to enhance supply chain performance. It allows companies to better coordinate their activities with their supply chain partners that lead to increased performance. This study conceptualises and assesses several factors that influence the degree of information sharing in supply chains, namely integrated information technologies, internal integration, information quality and costs-benefits sharing. The relationship between the degree of information sharing and organisational performance is then tested. Data from 150 manufacturing companies were collected and proposed relationships are examined using structural equation modelling. The results show that integrated information technologies and information quality have positive influence on the intensity of information sharing. However, internal integration and costs-benefits sharing do not relate to the intensity of information sharing. This study finds that information sharing does not directly relate to organisational performance. Its relationship is mediated by collaboration practices with supply chain partners. This suggests that information sharing is essential but insufficient by itself to bring significant performance improvements. © 2013 Copyright Taylor and Francis Group, LLC.

Cahyadi M.N.,Hokkaido University | Cahyadi M.N.,Sepuluh Nopember Institute of Technology | Heki K.,Hokkaido University
Journal of Geophysical Research: Space Physics | Year: 2013

We studied ionospheric disturbances associated with the two large earthquakes in Sumatra, Indonesia, namely, the 2007 Bengkulu and the 2005 Nias earthquakes, by measuring the total electron contents (TEC) using a regional network of global positioning system (GPS) receivers. We first focus on coseismic ionospheric disturbances (CIDs) of the Bengkulu earthquake (M w 8.5). They appeared 11-16 min after the earthquake and propagated northward as fast as ~0.7 km/s, consistent with the sound speed at the ionospheric F layer height. Resonant oscillation of TEC with a frequency of ~5 mHz continued for at least 30 min after the earthquake. The largest aftershock (Mw 7.9) also showed clear CIDs similar to the main shock. A CID propagating with the Rayleigh wave velocity was not observed, possibly because the station distribution did not favor the radiation pattern of the surface waves. This earthquake, which occurred during a period of quiet geomagnetic activity, also showed clear preseismic TEC anomalies similar to those before the 2011 Tohoku-Oki earthquake. The positive and negative anomalies started 30-60 min before the earthquake to the north and the south of the fault region, respectively. On the other hand, we did not find any long-term TEC anomalies within 4-5 days before the earthquake. Co- and preseismic ionospheric anomalies of the 2005 Nias earthquake (Mw 8.6) were, however, masked by strong plasma bubble signatures, and we could not even discuss the presence or absence of CIDs and preseismic TEC changes for this earthquake. Key Points Bengkulu 2007 and Nias 2005 earthquake ©2013. American Geophysical Union. All Rights Reserved.

Semin,Sepuluh Nopember Institute of Technology
International Review of Mechanical Engineering | Year: 2012

In this article, previous work on the application of injector on CNG engines is reviewed. In the review of injector, the spray characteristics, the gas jet structure, the effect of injector nozzle geometry on fuel-air mixing, injector nozzle coefficients of discharge, injector nozzle spray tip penetration and cone angle as well as injector nozzle orifice shapes are outlined. Fuel-air mixing increases as the orifice diameter decreases. This can be a significant advantage for small orifice nozzles. However, multiple orifices are required to meet the desired mass flow rate as orifice diameter decreases. © 2012 Praise Worthy Prize S.r.l. - All right reserved.

Darmawan M.S.,Sepuluh Nopember Institute of Technology
Magazine of Concrete Research | Year: 2010

Different types of corrosion may arise in steel reinforcement, such as general corrosion, pitting corrosion, hydrogen embrittlement, stress corrosion cracking and corrosion fatigue. However, corrosion of steel reinforcement in reinforced concrete (RC) structures can be classified into two categories: general (uniform) corrosion and pitting (localised) corrosion. In general, concrete researchers use uniform corrosion to study the effect of corrosion on RC structures. This approach is not accurate for concrete structures subjected to chloride attack, which usually experiences pitting corrosion. This paper describes an accelerated corrosion test used to obtain statistical parameters of maximum pit-depths distribution of corroded steel in a RC structure. Using probabilistic analysis, these statistical parameters are combined with statistical parameters of RC beams (i.e. beam dimensions, concrete strength, steel yield strength, cover thickness, workmanship quality, in situ strength factor, model error for flexure and shear and also corrosion rate) to determine the effect of corrosion on flexural and shear strength of RC beams. Using the proposed pitting corrosion model improves service life prediction of RC structures in a chloride environment. © 2010 Thomas Telford Ltd.

This paper addresses the application of blind source separation technique for identifying dynamic parameters of a seismic-excited multi-story building from its measured response. The structure was an instrumented moment-resisting frame office building. Its acceleration responses at different building floors were recorded during four earthquakes occurred in 2002. In this study second order blind identification - a class of blind source identification technique-was employed to obtain the structure's dynamic parameters, i.e., natural frequency and damping factor. The results of this study were substantiated through comparison with the results of investigations carried out for dynamic parameter identification of the same building using different techniques. Results of this study were encouraging. It indicated that the methodology employed in this study could be beneficially applied for identifying dynamic parameters of the building under seismic ground motions. © 2013 The Authors.

News Article | January 27, 2016

Using lasers and a window in a ship's hull, researchers will assess how quickly the efficiency of the ship declines, and then how to balance fuel efficiency and the cost of putting a ship in dry dock to clean it. "Essentially we've built a laboratory worth thousands of dollars inside the hull of the ship. Once we clearly know how things are growing on the bottom, and the effect this has on fuel efficiency, we can suggest more informed anti-fouling strategies, saving time and money for boat operators and passengers," says Professor I Ketut Aria Pria Utama from Sepuluh Nopember Institute of Technology (ITS). The team combines the maritime experience of engineers from the Sepuluh Nopember Institute of Technology with fluid mechanics expertise at the University of Melbourne and the University of Southampton, along with protective coating group Hempel. As soon as a new ship enters the ocean it starts to accumulate fouling – bacteria settle within days, followed within weeks by plants and animals. It's a particular problem in the tropical waters of Indonesia and northern Australia. "The real costs for shipping operators are hard to determine," says Associate Professor Nicholas Hutchins of the University of Melbourne. "Research discussions with ship operators all go well until we say 'and now we just need to put a small hole in the side of your ship'. But our Indonesian collaborators persuaded the PT Dharma Lautan Utama line to allow us to install a 30cm window in the hull of one of their inter-island ferries, the 71 metre Dharma Kencana IX, which transports people between Java and South Sumatra." Normally a boat can do this route in two hours, but with a high amount of marine growth on the boat, the journey can easily take double the time. The US Navy estimated that for its Arleigh Burke-class destroyer, resistance due to fouling costs about $2.3 million per ship per year in extra fuel consumption. Modern container ships are 10 to 15 times heavier. So the waste of fuel could be much higher. For the fleet of ships operating in Australian and Indonesian waters the costs could be billions of dollars per annum. And there's a significant carbon footprint as well: a substantial proportion of the fuel burnt by a large ship is used to overcome drag, and even a moderate amount of biofouling adds substantially to this. "Fifteen thousand dollars of seed funding from the Australia Indonesia Centre has enabled us to reach out to industry and other collaborators to build this into a much bigger, $200,000 dollar project, including securing a collaborative grant with the University of Southampton in the UK," Nicholas says.

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