IOSR-JAP   Volume-6 ~ Issue-6 ~ Nov-Dec 2014

ABSTRACT: For the purposes of providing evidence-based knowledge of climate change and assessing solar energy resources in different parts of Nigeria, this paper provides a synopsis of the spatial and temporal variability of sunshine hours on the basis of data records obtained from 20 instrumental series covering the period 1961 – 2012. Basic data comprises monthly mean daily sunshine duration in hours obtained from the Nigerian Meteorological Agency, Oshodi, Lagos. Mann-Kendall's rank correlation tests, least square regression, Pearson's Product moment correlation, Time series plots, Bar charts and descriptive statistics were used for the analysis. The results indicate dominant significant downward trends and few significant upward trends. The months of November to February indicate highest monthly mean daily sunshine hours while July, August and September months indicate minimum sunshine hours. The monthly mean daily sunshine hours show elevation and latitudinal dependence, increasing with altitude and latitudes of the synoptic stations. The stations record high coefficient of variation that shows neither elevation nor latitudinal dependence. The results are consistent with other studies carried out earlier at different temporal and spatial scales across the globe.
Key words: Sunshine hours, Trends, variability, Mann-Kendall, Least square regression, Nigeria.

[1]. Albrecht, B. (1989). Aerosols, Cloud Microphysics, and fractional cloudiness. Science, 245 (4923), 1227 – 1239.
[2]. Alpert, P., and Kishcha, P. (2008). Quantification of the effect of urbanization on solar dimming. Geophys.Res.Lett, 35, doi:10.1029/2007GL033012.
[3]. Alpert, P., Kishcha, P., Kaufman, Y.J., and Schwarzbard, R. (2005). Global dimming or local dimming?: Effect of urbanization on sunshine availability, Geophys.Res.Lett, 32, doi:10.1029/2005GL023320.
[4]. Angell, J.K. (1990). Variation in United States cloudiness and sunshine duration between 1950 and the drought year of 1988. J.Clim, 3, 296 – 308, doi:10.1175/1520 – 044(1990) 003< 0296: VIUSCA> 2.0.co;2.
[5]. Dai, A., Trenberth, K., and Kark, T.R (1999). Effects of clouds, soil moisture, precipitation and water vapour on diurnal temperature range. J.Clim., 12, 2451-2473. Doi:10.1175/1520-0442 (1999) 012 <2451:0ECSMP> 2.0.c;2.

ABSTRACT: The Milne problem is studied for the case of one speed, time independent, plane symmetric transport equation. The scattering law is assumed isotropic plus a backward and forward leak. First of all, the solution for the angular intensity relevant to the assumed scattering law is expressed in terms of the solution of the transport equation with isotropic scattering. The integral version of the isotropic like transport equation is then solved using a suitable set of trial functions. The unknown expansion coefficients in the trial functions are shown to be solutions of a system of linear algebraic equations. Numerical results are listed and compared with the existing results.
Keywords: Transport equation, Angular intensity, Milne problem, Approximate expansion.

[1]. K.M. Case and P. F. Zweifel, Linear transport theory (Addison-Wesley, Reading, Mass., 1967).
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ABSTRACT: Radiative heat transfer in one dimension is studied in a plane – parallel geometry for an absorbing and isotropically scattering medium subjected to azimuthally symmetric incident radiation at boundaries. The integral form of the transport equation, which is weakly singular Fredholm integral equation of the second kind, is used .The unknown function in the integral form is expanded in terms of truncated Chebyshev polynomials in the optical variable. The collocation method is applied to obtain a system of linear algebraic equations for the expansion coefficients. Numerical calculations are done for the transmissivctivity, and exit angular distributions of slabs with various values of single scattering albedo. Comparisons between the present and available results in references indicate that our results are accurate, as shown in the tables.

Keywords: Radiative transfer, Isotropic scattering, planar slab, Reflectivity and transmissivity, Chebyshev polynomials, Collocation method.

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ABSTRACT: Solar concentrators or reflectors enhance the efficiency of solar cookers or solar plants. Curved surfaces are better concentrators due to their abilities to direct rays to their focal point. This work is carried out to illustrate how an array of plane mirrors of a given surface area concentrate solar energy more efficiently compared to a single mirror (plane surface) of equal surface area. The performances of the two identical solar cookers with reflectors made from single mirror and array of smaller mirrors are carried out. The result shows that the rate of temperature rise in the cooker with the array mirror is always higher than the corresponding rate for the single mirror.

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[6]. Franco, C. Federico, R. and Andereca, N. (2011) " International Journal of Photoenergy, Vol. 2011 Retrieved from http.//dx.doi.org/10.1155/2011/843209 on 10th September,2011.

ABSTRACT: Position sensitive gaseous detectors with reflective photocathodes provide an attractive solution for photon localization over very large sensitive areas, under intense magnetic fields mainly due to their ease of construction. We report Quantum efficiency measurement of two new organic semiconductor photocathodes PEDOT/PSS and TECEB in spectral region 190-250nm, which are proposed for use in photosensitive gaseous detectors. Photocathodes were prepared by using resistive thermal vacuum evaporation technique. QE were measured in vacuum at about 10-4Torr and both the photocathodes exhibit non-negligible quantum efficiency up to 230nm.

Keywords: Position sensitive gaseous detectors, Photon detection, Solid Scintillator Proportional Counter (SSPC), Reflective Photocathodes, Gas electron multiplier (GEM).

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ABSTRACT: Photocathode is an important component of gaseous detectors, which are instruments of choice for photon (gamma to visible range) detection. However, the main limitation is the degradation of photocathode used in such detectors at high radiation environment because of the heavy ion – bombardment. We have measured quantum efficiency of two new photocathodes were prepared from N,N′-Bis(3-methylphenyl)-N,N′-diphenylbenzidine (TPD) and 8-Hydroxyquinoline (Alq3) compounds. In comparison, maximum QE was obtained with TPD whereas Alq3 also showed better results. These photocathodes are air stable and easy to prepare. The obvious advantages of these photocathodes in gaseous detectors will be fast response and room condition operation.

Keywords:Gaseous Detectors, Photocathodes, Quantum Efficiency, Degradation, GEM

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[4]. A.Di Mauro, D. Cozza, M. Davenport, D.Di Bari, D. Elia, P. Martinengo, A. Morsch, E. Nappi, G. Paić, F. Piuz, S. Stucchi, G. Tomasicchio, T.D. Williams, Performance of large area CsI-RICH prototypes for ALICE at LHC: for the ALICE collaboration, Nucl.Instr. And Meth.A 433 (1999) 190.

ABSTRACT: This paper describes synthesis of gold naoparticles (AuNP's) using green tea leaves and the effect of Coumarin 314 (C314) laser dye is in attachement with the gold and silver nano particles. The main purpose of our research is to study the green synthesis of nanoparticles and to know the influence of green synthesized gold nano particles on C314 laser dye. The attachment of AuNP's with C314 laser dye possesses enhancement in optical absorption and fluorescence.

[1]. Manish Dubey, Seema Bhaduria, B.S. Kushwah, Digest Journal of Nanomaterials and Biostructures, 2009;4(3); 537-543
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ABSTRACT: The Fowler-Nordheim carrier tunneling slope constants for electron and hole conduction through MOS devices fabricated on silicon substrate can be utilized to determine the conduction and valence band offsets, carrier effective masses in the SiO2 and its unknown bandgap, independent of photoemission spectroscopic measurements of band offsets on SiO2/Si samples. The slope constants can be obtained from the electron and hole tunneling currents versus oxide voltage characteristics on a pair of n-MOS and p-MOS devices in accumulation. This characterization technique called BOEMDET, can be applied to other insulating materials grown or deposited on silicon, such as jet vapor deposited (JVD) nitride, HfSiON, SiOxNy, AlN, BN, high-K oxides, and transparent conducting oxides (TCO).

Keywords: effective mass, FN-tunneling, band offsets, metal-insulator-semiconductor

[1] J. Robertson, "High dielectric constant oxides", Eur. Phys. J. Appl. Phys., vol. 28, pp.265-291, Dec. 2004.
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ABSTRACT: The use of inverters in preference to generators as an alternative for un-interruptible power supply is gaining wide acceptability in developing countries, due to inverters' greater environmental compatibility. However, the major challenge remains local production of sufficiently high powered inverters for big loads and longer periods of time. In this study, effort is made to produce a robust 1 KVA inverter. Requirements for the implementation include locally sourced 80 Ah 12V deep cycle battery, IC SG3524 oscillator, MOSFETs and BJT types of transistors, diodes, transformer, relay, contactor, resistors, capacitors and other electronic components. The construction is divided into four units consisting of oscillator unit, MOSFET assembly unit, Transformer unit and battery charger monitor unit. Each constructed unit was independently tested for proper functionality before the composite coupling.

[1]. Hughes, A. and Smith, I. M. (1995). Hughes Electrical Technology, 7th Edition. ISBN: 0470234342. Longman Scientific and Technical.
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[3]. Osuwa, J. C. and Igwiro, E. C. (2010). Uninterruptible Power Supply Using Solar Rechargeable Battery, Physics International (1) 1: 77-82.
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ABSTRACT: This paper is about the investigation and analysis of dielectric and magnetic properties of the curious and promising P-2 layered oxides mainly for electrodes in rechargeable batteries.A solid state synthesis of the novel materials is taken up by taking NFMO as the guiding standard.Two more variants NMCO and NFCO are also synthesized.The structure is confirmed by xrd.The dielectric properties are studied by the cryostat apparatus and a high dielectric constant is observed.In the magnetic studies done by SQUID there is no long range magnetic ordering observed ,but an antiferromagnetic like transition is seen.

Keywords: Antiferromagnetic, Characterization, Dielectric, Layered material, NFMO, NMCO, NFCO, Solid state reaction.

1]. Ohzuku, T., Kitagawa, M. & Hirai, T. Electrochemistry of manganese-dioxidein lithium nonaqueous cell. 3. X-ray diffractional study on the reduction ofspinel-related manganese-dioxide. J. Electrochem. Soc. 137, 769775 ).(1990
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ABSTRACT: In this paper, we have studied non-self-similar gas motions in presence of magnetic field which result from the propagation of plane, cylindrical and spherical shock waves through the gas requires complicated and cumbersome calculations. An approximate method of calculation of such motions is taken from [1,3,4].
Key Words: shock waves, propagation of plane, cylindrical and spherical shock waves Mathematics subject classification 2010: 76L05, 76W05

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ABSTRACT: Totally of 40 samples of 6 different building materials rocks were collected from 11 quarries which are founding in south-west part of Yemen. all samples from quarry Basalt , Tuff ,Granite , SchistGranit , Migmatit and Limestone which are known as shown in table,3.1. Measurement were done by High Purity Germanium(HPGe) to determine the concentration natural radionuclide of (CTh , CRa and Ck). Activity Concentration Index(I) , Radium Equivalent(Raeq) , Dose rate (D) , Annual effective doses Equivalent(AEDE) ,

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