Open Access Original Research Article

The Wonderful World of Hammar’s Experiment

A. Sfarti

Physical Science International Journal, Page 1-5
DOI: 10.9734/PSIJ/2016/29643

In a rather terse note, published in 1935, G.W. Hammar explained his brilliant experiment destined to put away, once and for all, the notion of “aether entrainment”.  Certain physicists, such as Dayton Miller, insisted that the null result of the Michelson-Morley experiment and its repetitions could be explained in the framework of Galilean relativity as an artifact of the lab (and the interferometers) “dragging” with them the medium (“aether”)  necessary for light propagation.  Today, this very clever experiment is almost forgotten, taking a backseat to the more famous pillars of special relativity tests: Michelson-Morley, Kennedy-Thorndike and Ives-Stilwell. Maybe the stark parsimony of Hammar’s note (one page, no figures, no calculations) is the reason for overlooking this wonderful experiment. 

 

Open Access Original Research Article

Gross Alpha and Beta Activity Concentrations in Locally Processed Salt from Ebonyi State, Nigeria

B. U. Nwaka, P. I. Enyinna

Physical Science International Journal, Page 1-12
DOI: 10.9734/PSIJ/2016/28111

Salt lakes and small – scaled salt production in Ebonyi State, Nigeria have long interesting  history and the need to be informed of the radiological quality of the salt is essential to radiation measurement and protection agencies. Gross alpha and beta activity concentrations have been determined in locally processed salt samples and iodized sachet salt samples consumed in Ohaozara Local Government Area and neighboring towns in Ebonyi State using Protean Instrument Corporation (PIC) MPC 2000 DP proportional counter. The gross alpha and beta activity concentrations in Okposi Okwu salt were found to vary from 0.0057 to  0.0082  with a mean of 0.0063±0.0002 Bq/g and from 0.2393 to 12.12  with a mean of 1.763±1.160 Bq/g respectively; for Uburu salt between 0.0058 to  0.0068  with a mean of 0.0061±0.0001 Bq/g and from 0.2204 to 63.46  with a mean of 20.0150±8.1065 Bq/g for gross alpha and beta activity respectively; while the gross alpha and beta activity concentrations of the iodized sachet salt ranged from 0.0055 to 0.0067  with a mean of 0.0059±0.0001 Bq/g and 2.136 to 25.92  with a mean of 7.217±0.0001 Bq/g respectively. Findings showed that the mean gross alpha activity results for the three brands were in good agreement whereas, gross beta activity concentrations for Uburu salt and iodized sachet salt were respectively about 13.37 and 4.09 times higher than that of Okposi Okwu salt. The trend of the mean of gross alpha activity concentration of the three brands of salt in this study shows that Okposi Okwu salt > Uburu salt > industrial sachet salt while that of gross beta activity shows that Uburu salt > industrial sachet salt > Okposi Okwu salt. The results of the gross beta and, sum of gross alpha and beta activity concentrations are greater than the standard activity limit for general consumed foods which is given as 0.1 Bq/g. High consumption of Okposi Okwu salt brand by the populace may have radiological impact on them as a result of the relatively high level of beta radiation.  It is suggested that as a means of radiological protection, These salt brands should be screened for radioactivity concentration before consumption.

 

Open Access Original Research Article

Experimental Study of Thermophysical and Mechanical Properties of Refractory Clay Tilled into Straw-fiber Stabilized Blocks

Boukaré Ouedraogo, Kalifa Palm, Emmanuel Ouedraogo, Dieudonné Joseph Bathiebo, Sié Kam

Physical Science International Journal, Page 1-8
DOI: 10.9734/PSIJ/2016/29586

In this experimental study, we have determined both thermo-physical and mechanical properties of raw soil blocks stabilized with fiber straws. Also was studied, the influence of straw content incorporated in the blocks for both properties. Thermophysical properties are determined using a device we designed and produced in the Technical Block of the University of Antananarivo between November 2014 and September 2015. This device uses a hot plane. Mechanical properties are determined using a mechanical press.

The results of our study show that the stabilization of raw mud blocks with straws enables to improve both its thermal and mechanical properties. Indeed, stabilization has enabled to decrease thermal conductivity by 44.92%, diffusivity and thermal effusivity by 30.77% and 33.81% respectively relative to the blocks without stabilizer. But it increases the heat capacity of 6.81% compared to blocks without stabilizer.

The compressive strength has been increased by 58.96% and drying shrinkage has been decreased by 22.25%. The resistance to the maximum deflection is 0.477 MPa for 4.81% of straw rate.

Stabilizing the clay with a straw has improved these thermophysical and mechanical properties respectively in insulation and increased strength, showing that it can be used bearing material in the construction of bioclimatic habitats.

 

Open Access Original Research Article

MHD Stagnation Point Flow and Heat Transfer of a Nanofluid over a Non-isothermal Stretching Sheet in Porous Medium

G. Vasumathi, J. Anand Rao, B. Shankar

Physical Science International Journal, Page 1-11
DOI: 10.9734/PSIJ/2016/29926

The present study deals with the MHD stagnation point flow of Nanofluid past a non-isothermal stretching sheet in porous medium. The presence of Brownian motion and thermophoresis effects yields a coupled nonlinear Boundary Value Problem. The sheet is assumed to be permeable. Similarity transformations are invoked to reduce the partial differential equations into higher order nonlinear ODE’s. The transformed equations are solved numerically by using a well known finite difference scheme Keller-Box method. The analysis has been carried out for two different cases, namely prescribed surface temperature (PST) and prescribed heat flux (PHF) to see the effects of governing parameters for various physical conditions. The various non dimensional parameters effects with velocity, temperature and concentration profiles are discussed in detail with graphically and tabular form. The results indicate that increasing the Brownian motion parameter and thermophoresis parameter reduces the heat transfer rate at the surface. Increasing porosity parameter reduces the velocity of nanofluid and increases the temperature of nanofluid.

Open Access Original Research Article

Hα and Hβ Profile Variations in the Spectra of Early Supergiants HD198478 and HD187982

Y. M. Maharramov, A. R. Hasanova, A. M. Khalilov, A. Sh. Baloglanov, G. M. Haciyeva

Physical Science International Journal, Page 1-11
DOI: 10.9734/PSIJ/2016/29808

Profile variations in the Ha and Hb lines in the spectra of the stars HD198478 and HD187982 are investigated from spectroscopic observations acquired in 2010-2011, 2013-2015 at the Cassegrain focus of the 2-m telescope at the Shamakhy Astrophysical Observatory. The spectral resolution is approximately 15000.

The emission and absorption components of the Ha profile are found to disappear on some observational days in the spectra of HD198478. It is suggested that the observational evidence for the non-stationary atmosphere of HD198478 can be associated in part with non-spherical stellar wind.

It has been revealed that absorption in the line of Ha has variable structure in the spectrum of the star HD187982 depending on the activity phase of the atmosphere. The profile of the line has normal P Cyg type in the active phase of the star atmosphere. The emission component in the red wing of the profile forms and disappears. It is supposed that such variations may be due to non-stationary and strong flow substance in the atmosphere of this star.

Open Access Original Research Article

Thermomechanical Characterisation of Compressed Earth Blocks Added with Sawdust

Chakirou Akanho Toukourou, Guy Clarence Semassou, Clément Ahouannou, Sèfiou Avamasse, Antoine Vianou, Gérard Degan

Physical Science International Journal, Page 1-9
DOI: 10.9734/PSIJ/2016/29393

The study of mechanical resistances twined to standards dispositions allows keeping a composition of CEB measured out 10% of cement and 2% of Tectona grandis sawdust. This composite material offers a higher strength compared to the one obtained with Afzelia sawdust. The method of asymmetric hot plan has been used to determine the thermal conductivity of the material and deduct the thermal parameter such as the diffusivity, the effusivity and calorific capacity. This method proceeds by a quadripolar modelisation 1D and allows to represent with a good precision the temperature in the center of a drill linked to the studied samples. The results that are obtained have shown that the addition of sawdust to the ordinary compressed earth blocks has clearly improved isolation performances of the final composite material.