Browsing RP-Department of Physics by Issue Date

Now showing items 1-20 of 114

    • Lead contamination of traditional hand-dug wells in parts of Kwale County, Kenya 

      Chege, M. W.; Hashim, N. O.; Merenga, Abdullah S.; Tschiersch, J. (International Journal of Physical Sciences, 201-05)
      People’s health, behavior and intellect to a certain extent are a function of their environment. One important component of this environment is water, a basic necessity that human beings cannot do without. The water ...

    • Emergence of Advance Waves in a Steady-state Universe 

      Hobart, R. H. (Kluwer Academic Publishers, 1979)
      In standard Wheeler-Feynman electrodynamics advanced waves from any source are absolutely canceled by the advanced waves from the absorber responding to that source. The present work shows this cancellation fails over ...

    • Solar wind controlled pulsations: A review 

      Odera, T. J. (Reviews of Geophysics, 1986-02)
      Abstract Studies of the solar wind controlled Pc 3, 4 pulsations by early and recent researchers are highlighted. The review focuses on the recent observations, which cover the time during the International Magnetospheric ...

    • PC 3,4 magnetic pulsations observed simultaneously in the magnetosphere and at multiple ground stations 

      Odera, T.J.; Swol, D.V.; Russell, C.T.; Green, C.A. (Reviews of Geophysics, 1991-09)
      Periods of magnetic conjugacy between ISEE and the magnetometer array of the Institute for Geological Sciences have been examined to search for the simultaneous occurrence of Pc 3,4 magnetic pulsations. When compressional ...

    • The Hall effect and electronic conduction in amorphous Si 

      Okumu, John; Holender, J. M.; Morgan, G. J. (Taylor &Francis, 1995-02-17)
      We show that the random-phase model for the electronic wavefunctions gives very reasonable agreement with recent computations of the conductivity for amorphous Si. Furthermore the model also yields the double-sign anomaly ...

    • A Preliminary Study of Relative Permeability in Geothermal Rocks Authors 

      Ambusso, W.; Satik, C.; Castanier, L.M.; Horne, R.N. (Geothermal Resources Council, Davis, CA (United States), 1995-12-31)
      This paper reports preliminary experimental and numerical efforts towards obtaining steam-water relative, permeability and capillary pressure functions under steady-state and adiabatic conditions. In the experimental ...

    • Determination of Relative Permeability for Steam-Water Flow in Porous Media 

      Ambusso, W.; Satik, C.; Horne, R.N. (Society of Petroleum Engineers, 1996-01-01)
      A set of relative permeability relations for simultaneous flow of steam and water in porous media were obtained from a steady state experiment. The experiment was conducted under conditions that minimize most of the ...

    • Analysis of Soil for Trace Elements along Two Highways of Kenya 

      Hashim, N.O.; Kinyua, A. M.; Mangala, M. J.; Rathore, I. V. S. (Faculty of Science Kenyatta University, 1998)
      Energy dispersive X-ray fluorescence technique has been used to study the levels of lead and other toxic trace elements in the soil samples collected along two major highways (Mombasa and Thika) of Kenya at the various ...

    • A generalized Coulomb-projected Born Calculation using Screened Coulomb Potential 

      Singh, C. S. (Faculty of Science Kenyatta University, 1998)
      The Coulomb-projected Born method proposed by Geltman has been generalized by using the screened Coulomb potential of the form in place of the nuclear potential experienced by the incident electron. The results obtained ...

    • Ohmic and Space-Charge-Limited Conduction in Doped Amorphous Arsenic Triselenide 

      Wafula, A. B. (Faculty of Science Kenyatta University, 1998)
      The electrical characteristics of asernic triselenide have been studied. A number of parameters is evaluated on the basis of the theory of space-charge limited conduction and the following values were obtained: hole ...

    • Optical studies of doped amorphous arsenic triselenide 

      Wafula, A. B.; Dod, T. S. (Faculty of Science Kenyatta University, 2000)
      Photoconductivity of As2Se3:Alx and As2Se3:Cux was investigated using light of visible spectrum of wavelengths A. = 0.67 um & 0.47 urn. Two regimes were observed: regime 1, the high temperature region above maximum ...

    • Mechanical stresses upon crystallization in phase change materials 

      Njoroge, W. K.; Kalb, J.; Wamwangi, D.; Wuttig, M.; Spaepen, F. (American Institute of Physics, 2001)
      Crystallization processes in different Te alloys, employed in phase change materials for optical data storage, have been investigated by in situ mechanical stress measurements. Upon crystallization a considerable stress ...

    • Calculation of linear and non-linear optical properties of amorphous Silicon 

      Okumu, J.; Morgan, G.J. (Faculty of Science Kenyatta University, 2001)
      We have used the random phase model for the electronic wave functions to calculate the imaginary part of the dielectric function 82 (m) and the magnitude of the third harmonic generation, 11'3(OJ ~ using a model structure ...

    • Crystallization kinetics of sputter-deposited amorphous AgInSbTe films 

      Njoroge, Walter K.; Wuttiga, Matthias (American Institute of Physics (AIP), 2001-10)
      AgInSbTe films have recently attracted considerable interest as advanced materials for phase change recording. For this application the determination of crystallization kinetics is of crucial importance. In this work the ...

    • Density changes upon crystallization of Ge2Sb2.04Te4.74 films 

      Njoroge, W. K.; Wöltgens, H. W.; Wuttig, M. (2002-05)
      The density of sputtered Ge2Sb2.04Te4.74 thin films upon annealing has been precisely determined by x-ray reflection and compared to the values determined from x-ray diffraction (XRD) data. The film density increases in ...

    • In situ measurements of thickness changes and mechanical stress upon gasochromic switching of thin MoOx films 

      Okumu, J.; Koerfer, F.; Salinga, C.; Wuttig, M. (American Institute of Physics (AIP), 2004)
      Thin films of MoOx coated with platinum as a catalyst were prepared by dc magnetron sputtering from a molybdenum target in an oxygen and argon atmosphere. The films were colored and bleached by exposure to diluted hydrogen ...

    • Study of angular correlation parameters using a distorted wave model 

      Singh, C. S. (Kenyatta University, 2004)
      We have used a distorted wave model suggested by Singh in calculating the angular correlation parameters f... and R for electron-hydrogen collision. In this model the initial state distorted wave is generated by the ...

    • Influence of dielectric capping layers on the crystallization kinetics of Ag5In6Sb59Te30 films 

      Njoroge, W. K.; Dieker, H; Wuttig, M. (American Institute of Physics, 2004)
      AgInSbTe alloys are attractive storage materials for phase change recording utilizing both optical and electronic contrast. The demand to decrease the thickness of such storage layers increases the significance of the ...

    • Current-voltage characterization of doped polystyrene thin films with view to gas sensing 

      Wafula, A. B.; Katana, G. (Kenyatta University, 2004)
      Current-voltage measurements of iodine doped polystyrene thin films as a function of dopant concentration, temperature and radiation have been carried out. The thin films were prepared by solution casting method taking ...

    • An investigation of the repeatability of calibration factors in gamma-ray spectrometry of geological materials 

      Mustapha, A.O.; Patel, J. P.; Rathore, I. V. S.; Hashim, N. O.; Otwoma, D. (Elsevier, 2004-01)
      A NaI(Tl)-based gamma spectrometer for the analysis of geological materials was calibrated using the IAEA reference materials RGU-1, RGTH-1 and RGK-1. To simulate typical geological samples, two additional standards were ...