Joseph Calistus Nihal Rajendra

PurposeThe purpose of this study is to identify the learner characteristics attributable to the likelihood and the duration of programme completion in the Bachelor of Science (BSc) and Bachelor of Technology Honours in Engineering (BTech) degree programmes of the Open University of Sri Lanka (OUSL).Design/methodology/approachData were gathered from the re-registrants for the degree programmes in the academic year 2020/2021, using a questionnaire developed as a Google form. The sample consisted of 301 and 516 re-registrants from the BTech and BSc programmes respectively. Influential factors were identified using Kruskal Wallis test (for duration of completion), binary logistic regression (for likelihood of completion) and Chi-squared test (associations between presage and process factors).FindingsEntry qualification, age and time management skills at entry had significant effects on duration of completion. Attendance at academic activities, organizing time for self-studies and the co...

TEX is an ASCII text-based markup language. In a scheme of automated scientific document preparation LTEX provides the foundation, which is also a markup language created from TEX. In this work a user-friendly editor was developed integrating the Tamil text-based ASCII characters with the Tamil LTEX characters via character mapping process. These conversions of Tamil text-based fonts have been interfaced with the LTEX engine to produce LTEX out put such as DVI, PDF and PS.

Three Bismuth based superconducting samples with the composition Bio.rPbQ.sSrCaCui.sOy were prepared using different solid state reaction techniques. The BiiOz* P6O, SrCOz and CuO powders o/99% purity were used as starting raw materials. The powders were mixed with the nominal cation ratio Bi : Pb : Sr : Ca : Cu = 0.7 : 0.3 : 1 : 1 : 1.5 and then mixed well using dry grinding, wet grinding and wet ball milling methods. The powders were calcined at 820°C and pallets of diameter 13 mm and thickness 1 — 2 mm were prepared from the calcined powder under 300 kg cm~2 pressure. The samples were then sintered at different appropriate temperatures. The resistance measurements at low temperatures were performed on three samples using a resistivity probe in the temperature range from 55K to 200 JFf. The samples prepared by dry grinding, wet grinding and wet ball milling methods have shown the superconducting transition Temperatures TC at 112K, 115X and IWK respectively. TCO of the three samples were found to be 7QK,8QK and 6&K respectively. In this work we developed a technique and successfully achieved a temperature as low as 55K while the resistivity probe was in liquid nitrogen.

Impedance Spectroscopy and Mott-Schottky measurements are powerful tools used to investigate the dynamics of mobile charges in solid materials to characterize their electrical properties. Composite films made with different compositions of SnO2 and, SiO2 extracted from rice husk were characterized using the above techniques. Impedance of the films varied significantly with the composition and had the maximum impedance when SiO2 was 30%, which was one order of magnitude higher than the impedance of the SiO2 films. Dielectric loss of the film was also found to be minimum at this composition. These results were attributed due to the enhancement of the permittivity of the composite at the above mixing ratio of SiO2 and SnO2. The flat band potential of the composite films at different compositions showed no significant difference, so that the two materials seems to remain unbound after sintering at 450 C.

Rice Husk (RH) is one of the main agricultural wastes available abundantly in Sri Lanka. Physical properties such as moisture content, average bulk density and porosity of seven varieties of RH found commonly in the western province of Sri Lanka were studied in this research. Moisture content varies between 10.38%-12.80%, the average bulk density varies between 372.90 kg m-3-523.94 kg m-3 and the porosity varies between 46%-68% of these samples. The highest amount of silica was estimated as 98.2% for BG300 variety of RH and the lowest amount of silica was estimated as 78.3% for Suwandal variety of RH. A typical SEM image and XRD analysis was done to characterize the extracted silica from Rice Husk Ash (RHA). Considerable reduction in particle size of silicain RHA from 10.1 Å to 8.10 Å was observed after the synthesis process.

INTRODUCTION Student engagement is a key factor in determining the academic success of any student 1 . Hence, academic institutions must search for interventions for improving student engagement in increasing retention and completion rates of their programmes. This is especially true in Open and Distance Learning (ODL) where the completion rates are intrinsically low. Motivation and competency of students, students' transactions with teachers and peers, institutional support received by students, realization of students' social beliefs and practices and support by family and friends are identified as key factors that positively influence student engagement

Solid helium can apparently grow on certain surfaces while on others it is inhibited and solidification takes place away from the adsorbent walls. In this paper we present experimental data on helium inside grafoil, on which surface solid He-4 appears to be able to grow, and also inside the pores of Vycor glass in which evidence suggests that the solid phase forms in the centre of the pores. We present data on both the specific heat and the pressure-temperature relation for these two situations. Melting takes place at pressures below those of the bulk melting curve in the case of grafoil, and above in the case of Vycor. An analysis is made of the measured heat capacities below the melting anomalies, and their temperature dependence indicates that inside both grafoil and Vycor a possible explanation is that the main excitations present are rotons with an energy gap of about 6K to 7K. This would indicate the presence of a liquid phase down to our lowest temperatures, and this observat...

ABSTRACT The phenomenon of the shifts in the freezing and melting temperatures of various elements inside media with small pores is well established. What is not yet well understood are the attendant changes in the properties of the liquid and solid phases at these anomalously low temperatures. In our present work we produce various analyses of our experimental data to produce estimates for the way in which the confinement of pressurized helium inside the pores of Vycor glass has changed its properties from those of the bulk phase. Simultaneous measurements of pressure and heat capacity, coupled with quantitative measurements on the amount of helium sample inside our porous glass, allow a significant number of parameters to be examined. In particular the entropy difference between the liquid and solid phases is presented, as well as the volume difference between these phases. At least the former of these two properties appears to have values substantially less than that observed in the bulk phase. Jin Zin has now returned to Nanjing University, Nanjing, China

ABSTRACT We have measured the specific heat of hydrogen inside the small pores of Vycor glass at temperatures extending down to 4K. The latent heat associated with freezing when cooling, and with melting when warming, is clearly seen. When this latent heat is compared with that of bulk hydrogen it appears that only a fraction of the hydrogen inside our pores takes part in the solid-liquid transition. Furthermore the specific heat measured at temperatures below the latent heat anomaly is clearly much larger than the specific heat of the bulk solid phase. It is also much larger than the T2 specific heat expected for the monolayer of hydrogen next to the glass wall. If the large specific heat is due to phonon modes, they are unusually soft. It it interesting that the data also fit a roton-type specific heat, with a roton gap of about 23K.

ABSTRACT We describe measurements of the specific heat of parahydrogen in Vycor porous glass, using two different methods, between 6K and 15K. Results from the first method are very similar to those from other laboratories, showing broad peaks at solidification and melting at temperatures well below the bulk, and decreasing smoothly at lower temperatures. The second set were carried out very slowly and we believe are much closer to thermodynamic equilibrium. They show new phenomena not resolved in the previous measurements, namely three distinct peaks in the freezing anomaly, and at lower temperatures a small cusp-like feature which is reproducible in four separate experiments over a period of several weeks. Below the anomaly the specific heat follows a roton-type function, but these measurements cannot determine whether superfluid is present.

ABSTRACT We have measured the heat capacity of molecular hydrogen in Vycor porous glass from 6K to 15K using two different methods. The first gives results similar to previous work, with broad peaks corresponding to freezing and melting and at lower temperatures a smooth decrease. The second, which are much closer to thermodynamic equilibrium, resolve three distinct peaks at freezing and reveal a small reproducible anomaly at a lower temperature, not previously observed. Below the anomaly the results fit a roton-type function, and we discuss the possibility that this is consistent with a superfluid state, although our experiments cannot detect it.