Optimization of load balance link layer protocol for nodes with multiple channels and interfaces in wireless mesh networks: A comprehensive review

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Effect of Relative Humidity on Arctic Aerosols

In this paper, the authors investigated some microphysical and optical properties of arctic aerosols extracted from the data base Optical Properties of Aerosols and Clouds(OPAC) to determine the effect of hygroscopic growth at the spectral range of 0.25?m to 2.5?m and eight relative humilities (RHs) (0, 50, 70, 80, 90, 95, 98, and 99%).The microphysical properties extracted were radii, volume mix ratio, number mix ratio and mass mix ratio as a function of RH while the optical properties are scattering and absorption coefficients and asymmetric parameters. Using the microphysical properties, effective growth factors of the mixtures were determined while using optical properties enhancement parameters were determined and then parameterized using some models. We observed that the data fitted the models very well. The angstrom coefficients which determined the type of particles size distribution increases with the increase in RHs except at the delinquent point where it decreases with the increase in RHs. The mixture was determined to have bimodal type of distribution with the dominance of fine mode particles but non-spherical. Keywords: microphysical properties, optical properties, hygroscopic growth, enhancement parameters, models, parametrisation

Geometry optimization and vibrational frequencies of tetracene molecule in gas phase and in methanol based on Density Funtional Theory and Restricted Hartree-Fock

Tetracene is an organic semiconductor with chemical formula C18H12 used in organic field effecttransistor (OFET) and organic light emitting diode (OLED). In this work, the molecular geometry (optimized bond lengths and bond angles), vibrational frequencies and intensities, HOMO-LUMO Energy gap and Atomic charge distribution of the Tetracene molecule in gas phase and in solution were calculated and reported. Restricted Hartree-Fock (RHF) and Density Functional Theory (DFT) with different basis sets were employed for the task. Windows version of Gaussian 03 software was used to perform all the calculations. The results obtained show that the bond length obtained using RHF has the lowest average value of 1.072Å and that obtained using DFT has the lowest average value of 1.085Å in gas phase. In Methanol, it is observed that at RHF level, the lowest average value was 1.075Å and at DFT level was 1.087Å. This shows that the values are a bit higher in methanol than in gas phase which implies that the bonds will be slightly stronger in gas phase than in methanol. The strongest bonds in tetracene molecule are those of C20-H28, C23-H29 and C24- H30 in both gas and methanol. The weakest bonds are those of C6-C12 and C6-C14.The bond angles were found to be so closed to 1200 at both levels of theory for all basis sets used suggesting that the molecule is planar benzene in which the C atoms are sp2 hybridized. The calculated HOMOLUMO energy gap shows that the molecule will be slightly more stable in chemical reaction in gas phase than in methanol. DFT values of the energy gap appeared to be closer to the reported experimental value of 2.6eV than those obtained by RHF. The atomic charges distribution was found to be very sensitive to the basis sets which presumably occur due to polarization. From the results obtained for vibrational frequencies, it shows that tetracene molecule would be more stable in gas phase that in methanol as a result of no imaginary frequency found in gas phase. This confirms the stability of the molecule as stated in the results of HOMO-LUMO energy gap. The calculated vibrational frequencies show that the most intense frequency was obtained to be 924.9862cm-1 at 146.7973KM/mole by RHF/3-21G in gas phase while at B3LYP/3-21G, it has the most intense frequency of about 474.1260cm-1 at 390.1077.2845MK/mole in methanol.Keywords: Optimixation, Methanol, Gas, Frequency, Tetracen

Analysis of auroral electrojet magnetic indices

In this paper magnetic indices were extracted from World Data Center (WDC) for geomagnetism forsix years (2008 to 2013). The indices extracted are  AuroralElectrojet (AE), Auroral Upper (AU), Auroral Lower (AL) and Auroral Oval (AO). The indices daily values measured at 24 hours Universal Time (UT) were averaged to monthly values. Time series statistical analysis was carried out on the monthly averaged data using SPSS version 16.0 with expert modeler, to determine the level, trend and seasonal  variations of the indices.From the results obtained after the statistical analysis, it can be seen that the indices have seasonal patterns of which AE, AL and AO as March but AU has July. Also from the values of the coefficient of determination, R2, it can also be concluded that AE and AL can be better predicted from the models than AU and AO. From the results obtained, simple seasonal model for AE, AL, and AO, and winter’s additive for AU was determined. Using the values of R2, it can be seen that the models for AE and AL can be used to predict or make forecast of the behavior of the indices. It was also discovered that level (alpha) has more significant contributions in the behavior of the system than seasonal.Keywords: Magnetic indices, World Data Center, Auroral, Level, Trend, Season, Expert modeler

A review on reversible logic gates

In recent years, reversible logic circuits have applications in the emerging field of digital signal processing, optical information processing, quantum computing and nano technology. Reversibility plays an important role when computations with minimal energy dissipation are considered. The main purpose of designing reversible logic is to decrease the number of reversible gates, garbage outputs, constant inputs, quantum cost, area, power, delay and hardware complexity of the reversible circuits. This paper reveals a comparative review on various reversible logic gates. This paper provides some reversible logic gates, which can be used in designing more complex systems having reversible circuits and can execute more complicated operations using quantum computers. Future digital technology will use reversible logic gates in order to reduce the power consumption and propagation delay as it effectively provides negligible loss of information in the circuit.   Keywords: Garbage output, Power dissipation, quantum cost, Reversible Gate, Reversible logic

Molecular Dynamics and Vibrational Analysis of Pentacene: RHF and DFT Study

The molecular dynamics of Pentacene molecule and its vibrational behavior is studied using the Gaussian software at the Restricted Hartree Fock and Density Functional Theory levels of computation. Two medium size basis sets, 6-31G and 6-31G* are used. The dipole moments, thermal energies and band gap computations for the molecule are obtained. The Infra Red (IR) and Raman vibrational frequencies are vividly examined and the most intense IR and Raman frequencies identified. The computed band gap at DFT level of theory for both basis sets is much in agreement with the experimental value. Keywords: Pentacene,  Hartree-fork, DFT, bond-angle, bondlength, Raman, frequencie

The effect of water solubles on Kelvin effects of the Maritime Polluted aerosols

In this work microphysical properties of Maritime Polluted aerosols wereextracted from Optical Properties of Aerosols and Clouds (OPAC) after varying the concentrations of water soluble at five different levels. The analytical expressions for the changes in the equilibrium relative humidity (RH), effective radii, effective hygroscopic growth, their magnitudes and fractional changes on the  effects of surface tension (the Kelvin effect) on the ambient aerosols were numerically  analyzed. The expressions were applied to two - one parameter models. It was  discovered that the increase in water soluble concentration caused decreased in the Kelvin effects which implies decrease in surface tension. The numerical analysis of the data showed that to the lowest order error.   Increase in the overestimation of the effective hygroscopic growth and decrease in the overestimation of the effective radii. On  the two models applied, we discovered that the fractional changes in hygroscopic growth increase in overestimation while there is decrease in  overestimation of fractional changes in effective radii. Finally, decrease in the underestimation of the fractional  changes in the equilibrium pressure it was discovered.Keywords: Kelvin effect, effective radius, effective hygroscopic growth, water soluble, ambient Relative Humidity, overestimation

Study of average seasonal variations of surface radio refractivity across some selected cities in Nigeria

The average seasonal variations of surface radio refractivity based on measurement of atmospheric pressure, temperature and relative humidity made across Yola (9o11' N, 12o30' E), Anyigba (7o 45' N, 6o45' E), Lagos (6o 27' N, 5o12' E), and Port-Harcourt (4o 48'N, 7oE) Nigeria, is reported. The measurement was made using wireless automatic weather station installed at the surface of each station under study. The study utilized three years of meteorological data measured from January 2010 to December 2013 to calculate the surface radio refractivity using empirical formula recommended by the International Telecommunication Union (ITU-R 453, 2012). The result shows that the average value of surface radio refractivity showed seasonal variations with high values during the rainy season and low values during the dry season with an increase in the value of surface radio refractivity of 242N units at Anyigba station to a maximum value of 384-N units at Lagos station. The result also shows that climatic condition is the force behind the seasonal variations of surface radio refractivity in all study stations.Keywords: Refractivity, Temperature, Atmospheric pressure, Relative Humidit

The Effect of Kelvin Effect on the Equilibrium Effective Radii and Hygroscopic Growth of Atmospheric Aerosols

In this paper we extracted microphysical properties of six types of atmospheric aerosols from Optical Properties of Aerosols and Clouds (OPAC) and numerically analyzed the analytical expressions for the changes in the equilibrium relative humidity (RH), effective radius, effective hygroscopic growth, the magnitudes and fractional changes in the effective radii  and the effective hygroscopic growth on the effects of surface tension (the Kelvin effect) on ambient atmospheric aerosols. The expressions were applied to two - one parameter models. We discovered from the analysis of the data extracted that, to the lowest order error, the change in the equilibrium RH, effective radii and effective hygroscopic growth depend on the compositions of the aerosols. From the two models used, we also discovered that the fractional changes in the ambient RH, effective radii and effective hygrosocopic growth, also depend on the aerosols compositions. Finally, we discovered that the magnitude of the Kelvin effect and its consequences on the atmospheric aerosols depend on the hygroscopicity of the aerosols. Keywords: Kelvin effect, effective radius, effective hygroscopic growth, atmospheric aerosols, ambient Relative Humidity