Open Access Original Research Article

Spatial and Temporal Distribution of Modified Radio Refractivity Gradient at 875 hPa and 700 hPa over Nigeria

S. E. Falodun, J. S. Ojo, V. O. Oviangbede

Physical Science International Journal, Page 1-13
DOI: 10.9734/psij/2019/v23i330154

The meteorological effects on radio wave signals propagating through the troposphere are of great concerns in the design and performance of radio communication systems. Often, the effect can lead to anomalous propagation conditions such as ducting, super refraction and sub refraction. In this paper, the spatial-temporal distribution of modified radio refractivity gradient and the effects on radio waves propagating at 875 hPa and 700 hPa pressure levels over sixteen selected locations aloft the four climatic regions of Nigeria are investigated. Five (5) years (2013-2017) meteorological parameters namely: air temperature, relative humidity and atmospheric pressure at ground level and 1 km above ground level were obtained from the European Center for Medium-Range Weather Forecast (ECMWF) at four synopses hours of the day. Modified radio refractivity and its gradient at the two pressure levels were computed using ITU- model. Results on a daily and seasonal basis shows similar trends at both 875 hPa and 700 hPa pressure levels, with higher values of modified radio refractivity gradient recorded at 700 hPa heights at the morning and night hours of the day. Results on seasonal basis shows that during the rainy season, modified radio refractivity gradients were high. On location basis, Port Harcourt (coastal region) recorded the highest value of modified radio refractivity gradient of about 115.5 M-units/km in the night time (00:00 hr. LT). The value depicts the occurrence of normal refraction in this location. The overall results will be useful for microwave links budgeting and design in Nigeria.

Open Access Original Research Article

Estimation of Growth Rate of Electromagnetic Plasma Wave through Vlasov-Maxwell Mathematical Frame in Ionospheric Plasma

S. J. Gogoi, P. N. Deka

Physical Science International Journal, Page 1-10
DOI: 10.9734/psij/2019/v23i330155

Unique forms of nonlinear wave energy exchange phenomena are observed in the Earth’sionosphere region. Energy upconversion of nonresonant plasma waves in the top ionospheric and auroral zone are noticed.Origin of these phenomena are tried to explained by linear andnonlinear theoretical approach.Wave-wave and wave-particle-wave interaction processes may be possible role takes place here.In this theoretical investigation we wish to derive probable growthrate expression of high frequency electromagnetic O-mode wave in the presence of low frequency electrostatic ion sound wave through wave-particle interaction process known as plasma maserinstability and estimate its value by using observational data.

Open Access Original Research Article

Modulational Instability of Ion Acoustic Waves in a Magnetized Plasma Consisting of Isothermally Distributed Hot and Cold Electrons

Sandip Dalui, Anup Bandyopadhyay

Physical Science International Journal, Page 1-13
DOI: 10.9734/psij/2019/v23i330156

Using the standard Reductive Perturbation Method a nonlinear Schr¨odinger equation is derived to study the modulational instability of small amplitude ion acoustic waves in a collisionless magnetized plasma composed of adiabatic warm ions, Maxwell-Boltzmann distribution of hot electrons as well as Maxwell-Boltzmann distribution of cold electrons, and the plasma system immersed in an external uniform static magnetic field (B0 = B0ˆz) propagating along the z-axis.
The instability condition and the maximum growth rate of instability have been investigated analytically as well as numerically. We have studied the effect of each parameter of the present plasma system on the maximum growth rate of instability. In particular, it is found that the maximum growth rate of instability decreases with the increasing value of the ion cyclotron frequency with some set of values of the parameters associated with the present plasma system. Again, we have seen that the instability region decreases with the increasing value of the ion cyclotron frequency.

Open Access Original Research Article

Development of a New Type-I Isotherm for Correction of Langmuir Isotherm’s Over-estimation of Adsorption at Higher Pressures

Adeolu J. Alawode, Olugbenga A. Falode

Physical Science International Journal, Page 1-26
DOI: 10.9734/psij/2019/v23i330157

Different gas equilibrium adsorption models (or isotherms) with various theoretical frameworks have been applied to quantify adsorbed volume (V) of gas (or fluid) through pressure-volume behaviour at a constant temperature. Most often, Langmuir isotherm (representing Type I Isotherm) has been used in modelling monolayer adsorption even though it yields over-estimation at higher pressures thus contradicting the description of Type I isotherm. Here, higher pressures refer to pressures above the adsorption saturation pressure(Ps) . Hence, in this work, a new Type I adsorption isotherm involving pressure(P), adsorption saturation pressure(Ps) , maximum adsorbed volume  and adsorbate-adsorbent resistance parameter  was developed using kinetic approach. The developed adsorption isotherm is V= 

Capture2.PNG

and it shows that Vmax is attained when pressure increases to Ps , above which no further gas adsorption occurs. The developed isotherm can be used to model all cases of monolayer adsorptions of gases (or fluids) on adsorbents. The developed and Langmuir isotherms were used in modelling secondary low-pressure gas adsorption data of different adsorbents and the qualities of fit were statistically assessed. For laboratory methane adsorption on Turkey’s shale sample at 25°C, the developed isotherm yields a correlation with an R2 value of 0.997 and predicts a maximum adsorption volume of 0.0450 mmol g-1 at a Ps  of 2,005 psia. However, Langmuir isotherm yields a correlation with an R2 value of 0.989 and predicts a maximum adsorption volume (Langmuir volume,VL ) of 0.0548 mmol g-1 at infinite Ps. At the higher-pressure range, the developed isotherm reveals that Langmuir isotherm is not a Type I isotherm but a "pseudo-Type I” isotherm.

Open Access Original Research Article

Fermion Colour and Flavour Originating from Multiple Representations of the Lorentz Group and Clifford Algebra

Eckart Marsch

Physical Science International Journal, Page 1-13
DOI: 10.9734/psij/2019/v23i330158

Where do such fermion properties as colour and flavour come from? We attempt to give a possible answer to this question in our paper. For that purpose we use the reducible (1/2,1/2) representation of the Lorentz group. Then the fermion corresponds to a doublet, each component of which can be described by the standard Dirac equation. In this way we conclude that quark and lepton, when being considered as doublets, originate from the discussed multiple representations of the Lorentz group (LG) and the related Clifford algebra. In particular the threefold colour degree of freedom emerges naturally, and similarly the threefold generation degree, both being enabled essentially by the fact that the SU(2) group has three generators given by the Pauli matrices. The Dirac spinor, or for zero mass the chiral Weyl spinor, remains the building block of that theory.