University of Dschang

This paper investigates the behavior of a Hopfield neural network consisting of four interconnected inertial neurons arranged in a loop configuration. The mathematical equation that governs the overall dynamic of the model is consists of a set of eight first-order ordinary differential equations (ODEs) with odd symmetry. The system has 81 equilibrium points, some of which undergo multiple Hopf bifurcations as a control parameter is varied. The maximum number of coexisting states is related to the maximum number of active equilibrium points. Through numerical investigations, intriguing nonlinear properties are discovered, including both homogeneous and heterogeneous multistability and the coexistence of up to sixteen bifurcation branches, the presence of multi-spiral chaos, crisis phenomenon, period splitting and the oscillation death phenomenon. In order to obtain a comprehensive understanding of the dynamics, various tools are used, such as phase portraits, bifurcation diagrams, Poincare maps, frequency spectra, Lyapunov exponent spectra, and attraction basins. A Significant achievement of this study is the demonstration that coupling inertial neurons can be an effective method to generate multi-spiral chaotic signals. The overall dynamics is non-hidden and meticulous adjustment of the gradient connected to the fourth neuron allows to complete annihilate oscillations (no motion) in the neural network in a particular interval. Finally, an electronic circuit inspired by the coupled inertial neuron system is designed using Orcad-PSpice software and implemented using an Arduino-based microcontroller. The simulation results from PSpice and microcontroller confirm the findings from the theoretical analysis.

This study evaluates a wood gasifier cookstove to enhance household energy efficiency in Cameroon.The methodol. involved collecting data on temperatures and emissions, mainly carbon monoxide (CO), to assess the stove′s efficiency and emission reduction compared to traditional three-stone fires.The cookstove reduces boiling time by around 50 % compared to the traditional three-stone fire, from 17 to 8.33 min in cold-start mode and from 16 to 7.67 min in hot-start mode.Its thermal efficiency improves by 60 %, reaching 18.14 % compared to 11.28 % for the three-stone fire, indicating better conversion of wood energy into helpful heat for cooking.This leads to a 31.5 % reduction in wood consumption, using 1.72 kg of wood instead of 2.51 kg for the same cooking task, resulting in financial savings from 87.85 FCFA (euro0.13) to 60.2 FCFA (euro0.092).Carbon monoxide emissions are significantly reduced, enhancing indoor air quality and minimizing health risks.An integrated heat recovery system heats water using the stove′s waste heat, with a heat recovery efficiency of 34.72 %.These findings show that the wood gasifier cookstove is a faster, more efficient, and cost-effective alternative to traditional cooking methods.It reduces fuel consumption, pollutant emissions, and pressure on wood resources.Further research is needed to optimize the heat recovery system, integrate other biomass fuels, and assess long-term sustainability and household adoption.

Phytochem. investigation of the methanol extracts from the stem bark and leaves of Lannea velutina afforded a new diarylpropanoid (1) and eighteen previously described compounds from other plants.They included eleven flavonoids (2-12), three triterpenoids (13-15), three steroids (16-18) and one sugar (19).The structure of compound 1 was established by anal. of its spectroscopic and spectrometric data.All the isolated compounds are here reported for the first time from L. velutina species while only compounds 3, 6, 8, 10, 13-16 and 18 were previously reported from the genus Lannea.The extracts, fractions, and compounds were subjected to in vitro antibacterial assays against one Gram-pos. (Enterococcus faecalis ATCC 29212) and three Gram-neg. (Escherichia coli ATCC 8739, Salmonella Typhi ATCC 6539 and Pseudomonas aeruginosa 4C 76110) bacteria.The MeOH extract from the stem bark, its chromatog. fraction C and the EtOAc partitioned leaves extract showed significant activity against the growth of E. faecalis, E. coli and P. aeruginosa (16 ≤ MIC ≤64 μg/mL).Lannepoxide (1) inhibition activities were 16 ≤ MIC ≤128 μg/mL against the four bacterial strains.The findings demonstrated the chemotaxonomic significance of the isolated compounds and their potential as antimicrobial agents.