Geometrical design of stand pipe air distributors for the combustion of municipal solid waste in a fluidised bed

The new geometrical design of stand-pipe air distributor for the combustion of the municipal solid waste was presented. The new design of the air distributors enables penetration of incombustible and unburnt carbon through opening between the air distributors, thus providing easy maintenance work. The fluidized bed experimental rig was constructed using Perspex column in which air was supplied through the distributors below it. In order to establish the final geometrical design of the air distributors, several design parameters were investigated. The effect of orifice size, distance between orifice and distance between distributor pipes on the fluidization behaviour were studied. Investigation on the effects of various orifice sizes of 1.5 mm, 2 mm, 3 mm, 4 mm and 5 mm showed that the 3 mm orifice size exhibited the most stable fluidization behaviour. Investigation on some selected orifice distances of 10 mm, 20 mm, 30 mm and 40 mm also found that the 10 mm orifice distance exhibited stable growths of bubbles. Various pipe distances of 30 mm, 40 mm, 50 mm, 60 mm and 70 mm were also investigated and the most suitable pipe distance was 70 mm

Some New Fixed Point Theorems in Weak Partial Metric Spaces

          الهدف الرئيسي لهذا البحث هو استعراض ودراسة بعض النقاط الصامدة للدوال التي تحقق الشرط    في الفضاءات المترية الجزئية الضعيفة وتم إعطاء بعض التعميمات الجديدة لمبرهنات النقطة الصامدة لكل من ماثيوس وهيكمان. ان اهم النتائج التي حصلنا عليها هي توسيع وتوحيد العديد من النتائج في مبرهنات النقطة الصامدة وتعميم بعض النتائج الحديثة في الفضاء المتري الجزئي الضعيف كما اعطينا مثال لتوضيح نتائجنا.The main objective of this work is to introduce and investigate fixed point (F. p) theorems for maps that satisfy contractive conditions in weak partial metric spaces (W.P.M.S), and give some new generalization of the fixed point theorems of Mathews and Heckmann. Our results extend, and unify a multitude of (F. p) theorems and generalize some results in (W.P.M.S). An example is given as an illustration of our results

Microstructural and nonlinear electrical properties of ZnO ceramics with small amount of MnO2 dopant

A small amount of MnO2 dopant was added to ZnO system to see the improvement of the ceramic varistor microstructural and nonlinear electrical properties. The samples were prepared using solid-state reaction method and the microstructure and nonlinear electrical properties of the ZnO-xMnO2 system were investigated for x = 0.011 to 0.026 mol%, at three sintering temperatures, 1180°C, 1240°C and 1300°C for 1 and 2 h sintering time. The XRD and EDAX analyses showed that the main phase was ZnO while ZnMnO3 and ZnMnO7 as the secondary phases developed and distributed at the grain boundaries and triple point junction. The SEM observation revealed that prolonged sintering temperature and time improved the microstructure uniformity and strongly influences the nonlinear behavior of the samples. The maximum density and grain size have been observed at 92% of theoretical density and 10.8 μm, respectively and occur at the highest sintering temperature which is 1300°C. The value of nonlinear coefficient α is found to increase with the increase of MnO2 doping level up to 0.016 mol% and drop with further doping level increment for all sintering temperatures and time

Evolution of structural and magnetic properties in Ta/Ni_81Fe_(19) multilayer thin films

The interdiffusion kinetics in short period (12.8 nm) Ta/Ni81Fe19 polycrystalline multilayer films has been investigated and related to the evolution of soft magnetic properties upon thermal annealing in the temperature range 300-600-degrees-C. Small angle x-ray diffraction and transmission electron microscopy were used to estimate the multilayer period. Interdiffusion in the multilayers was directly computed from the decay of the satellites near (000) in a small angle x-ray diffraction spectrum. A kinetic analysis of interdiffusion suggests that grain growth is concurrent with grain boundary diffusion of Ta in Ni81Fe19. The evolution of soft magnetic properties of Ni81Fe19, i.e., lowering of 4piM(s) and increase in coercivity H(c), also lend support to the above analysis