Department of Mathematics

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Now showing 1 - 5 of 31
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    Producing Lightweight Concrete Using Tobacco Wastes
    (1st Conference of CIDA Restore Project, 2008) Fernando, P. R.; Parvathakeethan, A.; Einon Mariya, V.
    This study was carried out to determine the possibilities of using tobacco wastes in lightweight concrete production. The mixture combinations of materials such as tobacco waste, pumice, sand and cement were used to produce the samples. The results showed that produced material samples were in the lightweight concrete class according to values of consistency, unit weight, compressive strength and thermal conductivity. It was determined that the unit weight of lightweight concrete material samples ranged between 0.48–0.58kgdm-3 , compressive strength values ranged between 0.25–0.58Nmm-2 and thermal conductivity coefficients ranged between 0.198–0.250Wm-1 K-1. According to the observations, tests, experiments and evaluations on lightweight concrete material samples, it was concluded that the lightweight concrete with tobacco waste additives could be used as a material in construction.
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    Intervention of CIDA restore project for providing safe drinking water to the villages Palameenmadu and Puthukkudiyiruppu
    (2nd Conference of CIDA Restore Project, 2009) Fernando, P. R.; Krishanthan, S.
    The water crisis is one of the most significant issues in Sri Lanka after the Tsunami inclusive of Batticaloa district. The people those who are living in the Batticaloa district especially in Tsunami affected areas are suffering to get drinking water. The CIDA restore project targeted Palameenmadu and Puthukkudiyiruppu areas in order to find out the quality of drinking water. The questionnaire survey showed that even though 100% of the people from these two villages mainly depended on their home well to get drinking water before the Tsunami, none of them use their well for drinking purposes after the Tsunami. Based on this survey it was decided to test the water quality parameters in order to provide safe drinking water. There are 332 and 252 families in the Puthukkudiyiruppu and Palameenmadu areas respectively. It was very difficult to convince them to use their well, because they believed some wrong information about their drinking well water. Several kinds of activities and workshops were undertaken to remove their myths and to disseminate knowledge about the drinking water quality. At present all the villagers have started to use wells for drinking purpose after some practical activities and workshops.
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    Characterization of epitaxial Cr thin films
    (59th Annual Conference of the South African Institute of Physics, 2013) Prinsloo, A. R. E.; Sheppard, C. J.; Fernando, P. R.; Madau, P.
    Thin films and heterostructures of Cr and Cr alloys show fascinating properties that is not observed in the bulk material and research into their magnetic properties gives insight into dimensionality effects in these materials. This paper reports on the characterization of Cr thin films on MgO(100), MgO(110) and fused silica substrates, of thicknesses 20nm to 320nm. X-ray diffraction (XRD) results showed good epitaxial growth for films prepared on the single-crystalline MgO substrates, with Cr(002) and Cr(211), whilst those prepared on the polycrystalline fused silica were polycrystalline. The mosaicity and coherence length were determined from the XRD results. Standard four-point probe measurements were performed to obtain the resistance (R) of the films as function of temperature (T) the anomaly in the (T) curves was used to determine the Néel temperature (TN). TN versus t graphs for the various substrates show the behaviour expected for the samples prepared on MgO(110) and fused silica substrates, but rather unique behaviour is seen in this curve for samples prepared on MgO(100). This might be attributed to internal strain effects in these thin films.
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    Magnetic and transport studies on Cr100-xIrx alloys Single crystal
    (59th Annual Conference of the South African Institute of Physics, 2014) Fernando, P. R.; Sheppard, C. J.; Prinsloo, A. R. E.
    Abstract An investigation into the physical properties of Cr100-xIrx alloy single crystals, with x = 0.7, 1.5, 2.0 and 2.5, were previously used to determine the magnetic phase diagram of Cr100-xIrx alloy system around triple point concentration [1] where the various magnetic phases co-exist. The present study extends these results by considering the temperature (T) dependence of the Seebeck coefficient (S), specific heat (Cp) and Hall coefficient (RH) measurements, in addition to the electrical resistivity (ρ) (also measured previously). Well defined anomalies were observed in the electrical resistivity ρ(T) curves of all the samples, due to the antiferromagnetic to paramagnetic phase transition at the Néel temperature (TN). The S(T) curves of the samples with x = 0.7, 1.5 and 2.0 also exhibit anomalies associated with TN in the temperature range below 380 K. However, for x = 2.5 with TN = 391.5 K [1] no such anomaly is observed as the present measurements could only be done for 2 K ≤ T ≤ 380 K. Contrary to what is normally expected [2] it is noted that the anomaly related to TN is more prominent in the ρ(T) curves than in the S(T) curves. RH measurements, carried out from 380 K down to 2 K in a constant magnetic field of 6 T, shows only weak anomalies at TN for certain of the samples. The Sommerfeld coefficient (γ) is obtained by fitting Cp/T to the low temperature Cp/T versus T^2 data. The γ values found for the present single crystal samples fits in well with the γ versus electron-to-atom (e/a) ratio curve previously published for certain Cr alloys
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    Putative quantum criticality in the (Cr90Ir10)100-yVy alloy system
    (Journal of Applied Physics, 2014) Fernando, P. R.; Prinsloo, A. R. E.; Sheppard, C. J.; Lodya, L.
    Quantum criticality (QC) in spin-density-wave antiferromagnetic Cr and Cr alloy systems is a topic of current interest. In the present study, V was used as a tuning parameter to drive the Néel transition temperature (TN) of the (Cr90Ir10)100−yVy alloy series with 0 ≤ y ≤ 14.3 to zero and search for effects of QC in the process. The magnetic properties and possible QC behaviour (QCB) in this alloy system were investigated through electrical resistivity (ρ), specific heat (Cp), and susceptibility (χ) measurements as a function of temperature (T), indicating that TN is suppressed to zero at a critical concentration yc ≈ 9. The Sommerfeld coefficient (γ) is considered a key indicator of QCB and a peak is observed in γ(y) at yc on decreasing y through this concentration, followed by a sharp decreasing trend. This behaviour is reminiscent of that observed for γ of the prototypical Cr100−xVx QC system and allows for the classification of yc in the (Cr90Ir10)100−yVy alloy system as a possible QC point. Financial support from the NRF (Grant 80928 and 80626) and UJ is acknowledged.