University of Buea (UB) is found in Molyko, Buea, in the southwest region of Cameroon. It was founded as a university centre in 1985 and became a full-fledged university in 1992, following a government decree that re-organized state universities in the country. It is regarded as the best university in Cameroon and is one of two English speaking universities in Cameroon, alongside the University of Bamenda, which follow the British system of education. It serves citizens from both anglophone and francophone regions of Cameroon and from neighboring countries such as Nigeria and Equatorial Guinea.
Cocoa agroforestry expansion is widespread in eastern Democratic Republic of Congo, posing a significant threat to the integrity of protected areas. Despite this threat, the impact of this expansion on forest bird communities remains largely unexamined. This study investigated bird community composition in the Okapi Wildlife Reserve (OWR) and surrounding agroforestry areas using a combination of mist netting and passive acoustic monitoring. Specifically, it examined species richness, diversity, evenness, feeding guild abundance and habitat-specific indicator species across 19 sites. A total of 95 bird species were documented, with acoustic monitoring accounting for 73% and mist netting 43% of the recorded species. Significant differences in species richness, diversity and evenness were observed across habitat types. While cocoa farms exhibited higher species richness than primary forest sites or annual cultures, primary forests had the highest diversity indices, followed by cocoa farms and annual cultures. Bird communities were most even in annual cultures, compared to primary forest sites and cocoa farms. Additionally, 18 bird species showed strong associations with specific habitat types based on combined data from both mist netting and acoustic methods. This study highlights the importance of protected areas such as the OWR for sustaining bird communities, as well as emphasising the potential value of structurally complex agroforestry landscapes for subsets of forest bird communities. Furthermore, it demonstrates the effectiveness of combining mist netting and acoustic monitoring methods in understanding avian community composition amid land use changes. L'expansion des agrofor & ecirc;ts & agrave; cacao est tr & egrave;s r & eacute;pandue dans l'est de la R & eacute;publique D & eacute;mocratique du Congo, ce qui constitue une menace importante pour l'int & eacute;grit & eacute; des zones prot & eacute;g & eacute;es. Malgr & eacute; cette menace, l'impact de cette expansion sur les communaut & eacute;s d'oiseaux forestiers reste largement m & eacute;connu. Cette & eacute;tude a examin & eacute; la composition des communaut & eacute;s d'oiseaux dans la R & eacute;serve de faune & agrave; Okapis (OWR) et les zones agroforesti & egrave;res environnantes & agrave; l'aide d'une combinaison de captures avec filets et de suivis acoustiques passifs. Elle a examin & eacute; la richesse, la diversit & eacute; et l'uniformit & eacute; des esp & egrave;ces, l'abondance des guildes alimentaires et les esp & egrave;ces indicatrices sp & eacute;cifiques & agrave; l'habitat sur 19 sites. Au total, 95 esp & egrave;ces d'oiseaux ont & eacute;t & eacute; r & eacute;pertori & eacute;es, dont 73% document & eacute;es par le suivi acoustique et 43% par captures. Des diff & eacute;rences significatives en termes de richesse, de diversit & eacute; et d'uniformit & eacute; des esp & egrave;ces ont & eacute;t & eacute; observ & eacute;es entre les diff & eacute;rents types d'habitats. Si les plantations de cacao pr & eacute;sentaient une richesse en esp & egrave;ces plus & eacute;lev & eacute;e que les sites forestiers primaires ou les cultures annuelles, les for & ecirc;ts primaires affichaient les indices de diversit & eacute; les plus & eacute;lev & eacute;s, suivies par les plantations de cacao et les cultures annuelles. Les communaut & eacute;s d'oiseaux & eacute;taient plus uniformes dans les cultures annuelles que dans les sites de for & ecirc;t primaire et les plantations de cacao. En outre, 18 esp & egrave;ces d'oiseaux ont montr & eacute; une forte association avec des types d'habitats sp & eacute;cifiques. Cette & eacute;tude souligne l'importance des zones prot & eacute;g & eacute;es, telles que l'OWR, pour la pr & eacute;servation des communaut & eacute;s d'oiseaux, tout en mettant en avant la valeur potentielle des paysages agroforestiers & agrave; structure complexe pour certaines populations d'oiseaux forestiers. Elle d & eacute;montre en outre l'efficacit & eacute; de la combinaison des m & eacute;thodes de suivis par captures (filets japonais) et enregistrements acoustiques pour comprendre la composition des communaut & eacute;s d'oiseaux dans un contexte de changements d'utilisation des sols.
A common way to improve a beam-steering system based on a coupled oscillator array is to increase the number of oscillators to boost power, improve focus and resolution, and enhance steering precision. This study deals with the numerical analysis of the spatiotemporal dynamics of a network of N > 4 coupled triode-based van der Pol oscillator arrays for beam steering application, extending from a previous study in which the dynamics of N <= 4 coupled oscillators were successfully evaluated as phase shifters for electronic beam steering, achieving significant phase shifts and high-power outputs at ultrasonic frequencies. We create a comprehensive map of the different collective dynamic behaviors across different oscillating units in terms of the coupling strength and edge oscillator frequency. In addition to full synchronization, traveling waves, and oscillations death reported in the previous study, simulations reveal new patterns such as cluster traveling wave and 'imperfect' intermittent traveling wave as transitions between traveling waves and cluster state. Furthermore, the findings reveal that in addition to the emergence of new spatiotemporal patterns, the maximal phase shift decreases as the number of oscillators increases. For parameter settings in the beam steering region, the output waveform is applied as the input signal for linear phased array transducers. The results of the variation of the array aperture width show that the sound pressure peaks in the steered direction, while beam directivity improves with wider apertures. These results are in agreement with LTSPICE simulations and provide an alternative way to design high-power coupled oscillator arrays for beam steering applications.
This paper is aimed at establishing the theoretical study and microcontroller validation of the resistive-capacitive shunted Josephson junction (JJ) circuit with 2 pi - and 4 pi - periodic superconducting current components (RCSJJ2-4PSCC). According to the Routh-Hurwitz criteria, the rate equations for the RCSJJ2-4PSCC exhibit different behaviors based on operating conditions. When the system operates strictly in the 2 pi - or 4 pi - periodic regime, it may have either no equilibrium points or two equilibrium points, which are a stable-node and a saddle-node, influenced by the excitation current. In contrast, when the RCSJJ2-4PSCC functions under conditions where both the 2 pi - and 4 pi - periodic regimes coexist, it displays no equilibrium points, or two, four, or even eight equilibrium points. The stability of these points varies, particularly with the emergence of a pitchfork bifurcation based on the fractional parameter and stimulation current source. The hysteresis loop is sensitive to variation of the fractional parameter of the RCSJJ2-4PSCC. The RCSJJ2-4PSCC reveals various behaviors, including regular, period-doubling, bistable regular, bistable chaotic, and chaotic characteristics, as well as the coexistence of these states. These dynamical attractors show qualitative agreement with the results from the microcontroller implementation. By introducing via addition, a boosting parameter to the voltage, the orientations of the chaotic signals are adjusted dynamically by altering the boosting parameter.
This paper presents a theoretical investigation of the combined effect of the nonlinear thermal absorption coefficient and artificial roughness of an absorbent tube on the dynamics of a conventional photovoltaic thermal (PVT) water panel. The roughness and the nonlinear absorption coefficient are localized inside the tubes of the absorbent plate and in the photovoltaic (PV) module, respectively. The analytical expressions for the temperature on each layer of our system are determined from the energy balance equation. The simulations of the analytical expressions obtained are performed in the MATLAB software environment by considering the contributions of roughness, nonlinearity, and their combined effects. The results of our numerical investigations under standard test conditions reveal that the combined effect leads to a greater temperature reduction in the PV module than when roughness and nonlinearity are considered separately. Furthermore, the combined effect induces a reduction in the maximum temperature of the PV module by about 9°C, leading to an improvement of about 0.39
Agriculture remains one of the most vulnerable sectors to climate warming. Due to climate warming, there is a need for context specific actions to adapt agricultural systems and to build resilience. In Quebec, there are currently no studies that provide a provincial scale analysis of the impacts of seasonal climate on agricultural systems. As such, it is difficult to provide provincial scale predictions that will enhance adaptation with broad provincial scale implications. This paper provides a provincial scale analysis of the impacts of recent warming through changing seasonal temperatures and precipitations on the production of three crops (maple syrup, barley and soybeans) in Québec. Time series data for the period 1970–2023 on the production of maple syrup, soybeans, and barley were sourced from statistics Canada. CMIP6 shared socioeconomic pathways (SSP2-4.5) climatic data such as annual and seasonal temperature and precipitation for the period 1970–2023 were collected from Ouranos. The data were subjected to a test of stationarity through the Augmented Dick-Fuller Test (ADF), correlation analysis and multiple linear regression modeling. The results indicate that changing temperatures and precipitations have the strongest association on soybeans production, followed by barley and maple syrup. Decreasing summer and spring temperatures alongside increasing autumn precipitations have a positive and significant influence on soybeans production. Meanwhile, increasing autumn temperatures and declining autumn precipitations have a positive and significant association on barley production. Furthermore, declining winter temperatures have a significant positive influence on maple syrup production. This study concludes that rising temperatures and varying precipitation patterns significantly influence Quebec’s crop production and could affect the province’s food security and food trade.
