Debre Birhan University (DBU) is a university in the city Debre Birhan, Amhara Region, Ethiopia. It is one of thirteen new universities which were established in 2007 by the Ethiopian government.
To investigate the effects of fractional order ( α ), nanoparticle volume fraction ( φ ), magnetic field strength ( M ), and Brinkman permeability ( Br ) on both flow and heat transfer characteristics, a detailed parametric and statistical analysis is conducted. The statistical regression analysis shows that the volume fraction of nanoparticles and temperature have a strong positive correlation (coefficient = 0.94, p = 0.021) indicating that Mo2C MXene is an excellent heat absorption. On the other hand, the fractional parameter α has a strong negative effect on temperature field (coefficient = − 0.086, p < 0.001), which emphasizes its importance in describing the effects of thermal memory. The findings also indicate that, although MXene nanoparticles significantly increase thermal transport, an augmentation in magnetic field strength and Brinkman resistance cause a resistive Lorentz force and frictional drag, respectively, to prevent fluid flow. These results are physically informative about non-Fourier heat transfer in MXene-based nanofluids as well as offer invaluable information to developing high-performance thermal management systems and solar-energy applications.
Ecological and infection predator prey mathematical model is important tool for understanding complex systems and forecasting outcomes biologically. Incorporating saturation mass action incidence rates representing the rate of susceptible prey infection as a function of time along with time delay terms, makes more realistic and reflective of the inherent dynamics in the real-world systems. This study develops and analyzes delayed ecology model with disease where prey is infected by microparasites, and the predator consume both susceptible and diseased prey. The infection process is assumed to involve a constant time delay, referred to as the infection delay, while the predator reproduction following prey consumption introduces another delay, known as the gestation delay. Qualitative analysis of the model is verified. The consequence of delay terms in the model on the stability of the coexistence fixed point is investigated by treating the delay as a bifurcation parameter. The results indicate the existence of Hopf bifurcation and stability switching as delay cross a certain critical threshold values. Finally, we performed numerical simulations using ODE 45 and DDE 23 codes to support the theoretical and qualitative results in agreement with numerical findings.
Determining the geoid gravimetrically poses challenges which are complex mathematical computation and variability representation of the Earth, particularly when precision is necessary. This study aimed to compare the geoid determination methods namely: least squares collocation (LSC), Stokes integral, and Hotine integral methods. Shuttle Radar topography mission (SRTM), gravity anomaly, gravity disturbance, Earth gravity model 2008 (EGM2008), and global navigation satellite systems with levelling (GNSS/Levelling) data were used for the purpose of geoid determination methods. The LSC method was applied using the RCR technique. Whereas Stokes and Hotine integrals methods were computed based on KTH approach with essential corrections, including topographic, atmospheric, ellipsoidal, and downward continuation refinements. All three approaches yielded consistent geoid models with validation against benchmarks produced standard deviations of 0.069 m for LSC, 0.062 m for Stokes, and 0.061 m for Hotine. The findings demonstrate that the LSC provides reliable geoid approximations, Stokes and Hotine integrals attain marginally higher precision. This study highlights the significance of integrating airborne gravity data with global geopotential models and determined the gravimetric geoid model to contribute the development of an accurate nationwide vertical reference for Ethiopia.
The oscillatory motion of graphene oxide-Go nanoparticles in water lubricating Maxwell nanofluid flow for heat and mass transfer enhancement in steady and fluctuating regime is important significance of this study. The aim of this work indicates the temperature distribution, nanoparticle concentration rate and velocity field around stretching radiating-cylinder in drilling systems. The nonlinear radiating energy, entropy generation, mixed convection, buoyancy ratio and oscillatory effects are assumed for heat and mass performance. The partial differential based mathematical expressions are developed to estimate the values of current analysis. The oscillatory stokes conditions, complex variables, and primitive transformations are applied to develop steady and fluctuating results. The computational outputs are secured using very efficient methods like finite difference and Gaussian elimination. The graphical outputs are displayed through TecPlot-360 and FORTRAN. The fluid velocity field, energy, and concentration outputs are executed with the help of various physical factors. The steady friction and steady thermal rate are depicted and are used in transient algorithm to depict the fluctuating friction rate and oscillatory thermal-mass transport. The magnitude of fluid velocity, fluid temperature and fluid concentration enhances as Maxwell parameter is enhanced. The variation in fluid velocity amplitude and fluid temperature increases as radiating energy is enhanced. For high parametric range of Maxwell number, the steady skin friction and mass transfer increases but heat transfer decreases. At smaller Eckert number, the oscillations in transient skin friction, transient heat and mass transfer are enhanced. At higher Maxwell parameter, buoyancy and Schmidt number, the large amplitude in heat and mass oscillations is observed.
Nematode communities of ericaceous belt of the Bale National Park (Ethiopia) were examined in 2023 and 2024. The nematodes of Cambic and Folic Phaeozems formed under Erica tree and scrub life-forms were compared. The nematodes were isolated from soil by Baermann technique with subsequent assessment of total nematode abundance, taxonomic diversity, trophic guilds and ecological indices. The total abundance and biomass of nematodes differed significantly in Cambic and Folic Phaeozems. Also, the season significantly affected the soil nematode community’s features. The bacterivorous nematodes were dominant in all studied soils. Significant increases in fungivorous and decreases in omnivorous nematodes were recorded under Erica scrub life-form compared to tree life-form. The maximum number of phytonematodes was observed in Cambic Phaeozem. Mesodorylaimus, Hemicycliophora were eudominant genera in Cambic Phaeozem, whereas Acrobeloides, Plectus and Filenchus predominated in Folic Phaeozem. Rhabditis was dominant in all studied plots in all seasons. The trophic webs of studied soils were balanced and not disturbed.
