Open Access Short communication

Open Access Original Research Article

Spectral Clustering of Coral Reefs on the Small Islands, Spermonde Archipelago, Indonesia

Nurjannah Nurdin, Teruhisa Komatsu, Hiroya Yamano, Gulam Arafat, Chair Rani, M. Akbar AS

Physical Science International Journal, Page 1-11
DOI: 10.9734/PSIJ/2015/9390

Ecologically, coral reef has a function to protect the others component of marine and coastal ecosystem from pressure of wave and storm. If compared with the other ecosystems, coral reef that are most easily destroyed. Spermonde archipelago consist of more than one hundred small islands, which have the higher potential ecosystem especially of coral reef distribution. It is very influencing and provide higher contributes to the preservation of society, where most livelihoods depend on its shallow water and has high growing human activity. Remote Sensing technologies is an alternative to support the availability of spatial information resources, such as coral reefs in the large area. However, before remote sensing can be viewed as a practical monitoring and diagnostic tool for entire coral communities, there is a need to understand the spectral responses from individual coral.The aim of this study is identifying the spectral reflectance of coral reefs using hyperspectral data, it is expected that they can be used as references in discriminating healthy coral. Spectral reflectance data was collected in Spermonde Archipelago, Indonesia by using a hyperspectral radiometer. Correlation and cluster analysis support that distinct differences in reflectance spectra among categories existed. The analysis result of hyperspectral data shown that live corals, dead corals covered with alga and coral rubble are spectrally separable from each other.

 

Open Access Original Research Article

Electromagnetic Fields of Eigenmodes in Spherical Resonators

Yuriy N. Zayko

Physical Science International Journal, Page 18-25
DOI: 10.9734/PSIJ/2015/12727

In this article a physical theory of eigenmodes of electromagnetic resonators is presented. It is known, that Maxwell equations predict non-physical singular behavior of eigenmodes in spherical resonators. This shows that Maxwell theory is incomplete. For the improvement of the theory this problem is treated with the help of Maxwell-Einstein theory. Maxwell-Einstein equations take into account space-time curvature. Regular implementation of this approach permits to avoid the influence of singularity. Another result consists of that eigenmodes with large values of orbital angular momentum are not observable. An analogy with CMB in the Universe is made.

 

Open Access Original Research Article

Reliability of Argon Triple Point Cells Materializing the ITS-90 Temperature Fixed Point

M. G. Ahmed

Physical Science International Journal, Page 26-33
DOI: 10.9734/PSIJ/2015/12260

The triple point of argon is one of the defining fixed-points of the International Temperature Scale of 1990, ITS-90. Its value was assigned to be 83.8058 K by ITS-90. The thermal metrology laboratory of the National Institute for Standards, NIS has chosen, several years ago, to realize this fixed point through batch of thermometric cells. In the present work, three cells of different designs, composing the batch of reference, are inter-compared. The results of these inter-comparisons, over a period of time that reaches 17 years, showed the excellent reliability of these cells. No malfunction has arisen for the oldest cell "Ar-INM-42-NIS" over this period, it has 0.24 mK as the maximum variation among the other cells. For the other cells variations were found to be 0.17 and 0.18 mK for "Ar-NIS-QA" and "Ar-LNE-NIS-MC" respectively. The recent estimations of uncertainties for the batch of cells that include all the factors affecting the measurements showed values of 0.52, 0.33 and 0.31 mK for "Ar-INM-42-NIS", "Ar-NIS-QA" and "Ar-LNE-NIS-MC" respectively, and that cell "Ar-INM-42-NIS" has the maximum expanded uncertainty of 0.52 mK.

 

Open Access Original Research Article

Slip Effects on MHD Stagnation Point-flow and Heat Transfer over a Porous Rotating Disk

Navid Freidoonimehr, Mohammad Mehdi Rashidi, Shohel Mahmud, Foad Nazari

Physical Science International Journal, Page 34-50
DOI: 10.9734/PSIJ/2015/13222

The main concern of present study is to investigate the MHD stagnation flow past a porous rotating disk in the presence of the velocity slip condition. The boundary-layer governing partial differential equations (PDEs) are transformed into highly nonlinear coupled ordinary differential equations (ODEs) consist of the momentum and energy equations using similarity solution. The velocity profiles in radial, tangential and axial directions and temperature distribution are obtained via a semi analytical/numerical method, called Homotopy Analysis Method (HAM). An excellent agreement is observed between some of the obtained results of the current study and those of previously published studies. The influences of physical flow parameters such as magnetic interaction parameter (M) , slip factor (γ), rotation strength parameter (ω), and suction parameter (Ws) on the all fluid velocity components, temperature distribution as well as the skin friction coefficients and the rate of heat transfer are examined and analyzed. This simulation presents the feasibility of using magnetic rotating disk drives in novel nuclear space propulsion engines.

Open Access Original Research Article

Assessment of Activity Concentrations of Radionuclide with Depth in Wasteland Soils in Abeokuta, Southwest Nigeria

Bello Rasaq, Farinre O. Zainab

Physical Science International Journal, Page 51-60
DOI: 10.9734/PSIJ/2015/8726

A survey of natural radionuclide level with depth in wasteland soils in some locations in Abeokuta was carried out in February 2013. Samples were collected at 10 cm depth interval from each of the locations visited. They were collected into containers with length 9 cm and width 7 cm and then room dried. The different soil samples picked from different locations were not mixed together in order to avoid cross contamination of the soil samples. Analysis was carried out on each of the soil samples and the specific activity concentration of the radionuclides 40K, 238U and 234Th was measured using the model 802 series thallium activated sodium iodide detector NaI (Tl). The average specific activity values obtained for the 0 cm depth (surface) were 428.91±15.05 Bq/kg for 40K, 2.09±0.84 Bq/kg for 238U and 54.60±2.00 Bq/kg for 234Th. The gamma absorbed dose rate and effective dose equivalent were also calculated and an average of 55.5 nGy hr-1 and 0.136 mSv yr-1 were obtained. These obtained values were found to be below the recommended standard values by UNSCEAR which are 55.9 nGy hr-1 and 0.7 mSv yr-1. The results indicate that the radiation level within the dumpsites pose no significant health risk on the people living close to the dumpsite. Also, it was observed that as radionuclides are leached down, activity concentration reduces but may be altered again by factors such as the type of radionuclide, composition of subsurface materials, rate of ground water movement and the soil particles with which the radionuclides are connected.

 

Open Access Original Research Article

Friction and Wear Behaviour of Plasma Sprayed Fly Ash Added Red Mud Coatings

Harekrushna Sutar, Debashis Roy, Subash Chandra Mishra, Ananta Prasad Chakraverty, Himanshu Sekhar Maharana

Physical Science International Journal, Page 61-73
DOI: 10.9734/PSIJ/2015/12624

The present investigation aims at evaluating the effect of fly ash addition on sliding wear behaviour of pure red mud. Plasma sprayed coatings composed of red mud and varying percentage of fly ash were considered for the wear behavior study. Plasma spraying technique was used with varying levels of power namely 6, 9, 12 and 15 kW. Investigations of the coatings focused on tribological properties like sliding wear behaviour, wear morphology, wear mechanism and frictional force. Experimental investigations also include the effect of varying percentage of fly ash on dry sliding wear behaviour of pure red mud. Fly ash with 10, 20 and 50% by weight was mixed with red mud and sliding wear test performed using pin on disc wear test machine. The wear test was performed for sliding distance up to 942 m with track diameter of 100 mm and at sliding speed of 100 rpm (0.523 m/s); applying normal load of 10 N for a maximum duration of 30 minutes. The variation of wear rate and frictional force with that of sliding distance and time has been presented. Significant wear resistance was visible with the addition of fly ash due to increase in bond strength and dense film at the interface. Wear rate decreases with operating power up to 12 kW thereafter declines initiating other dominating parameters.

 

Open Access Original Research Article

Plane Symmetric Vacuum Cosmological Model with a Special form of Deceleration Parameter in ƒ(R) Theory of Gravity

V. B. Raut, K. S. Adhav, D. K. Joshi

Physical Science International Journal, Page 74-80
DOI: 10.9734/PSIJ/2015/13999

In this paper we have obtained vacuum solutions of the plane symmetric space-time in ƒ(R) gravity. The general solutions of the field equations of plane symmetric space-time have been obtained under the assumption of special form of deceleration parameter. The physical and geometrical aspect of the model is also discussed.