Exactly Solvable Two-Parameter Models of Relativistic δ′s -Sphere Interactions in Quantum Mechanics

We make a systematic study of two-parameter models of δ ′ s -sphere interaction and δ ′ s -sphere plus a Coulomb interaction. Where δ ′ s interaction denotes the δ ′ -sphere interaction of the second kind. We provide the mathematical definitions of Hamiltonians and obtain new results for both models, in particular the resolvents equations, spectral properties and some scattering quantities.

Assessment of the Wind Energy Potential of Two Burundian Sites

1-year hourly wind speed data from two Burundian stations, namely Bujumbura and Muyinga, have been processed in this work to bring an efficient help for the planning and installation of wind energy conversion systems (WECS) at those localities. Mean seasonal and diurnal variations of wind direction and wind shear exponent have been derived. Two-parameter Weibull probability density functions (PDFs) fitting the observed monthly and annual wind speed relative frequency distributions have been implemented. As shown through three complementary statistical tests, the fitting technique was very satisfactory. A wind resource analysis at 10 m above ground level (AGL) has led to a mean power density at Bujumbura which is almost thirteen fold higher than at Muyinga. The use of the empirical power law to extrapolate wind characteristics at heights from 150 to 350 m AGL has shown that energy potential of hilltops around Muyinga was only suitable for small, individual scale wind energy applications. At the opposite, wind energy potential of ridge-tops and hilltops around Bujumbura has been found suitable for medium and large scale electricity production. For that locality and at those heights, energy outputs and capacity factors (CF or Cf) have been computed for ten selected wind turbines (WTs), together with costs of electricity (COE) using the present value of cost (PVC) method. Amongst those WTs, YDF-1500-87 and S95-2.1 MW have emerged as the best options for installation owing to their highest CF and lowest COE. Moreover, an analysis of those two quantities at monthly basis for YDF-1500-87 WT has led to its best performance in the dry season. Compared to the average present COE of household hydroelectricity consumption, results of this study have evidenced economical feasibility and benefit of WECS setting in selected Burundian sites in order to supplement traditional electricity sources.

Characteristics, Constraints and Perspectives of the Fish Farming in Burundi

The fish farming was introduced in Burundi in about 1950s. Actually, several fish ponds were abandoned and many others were still unproductive. This study aims to present current state and perspectives of the fish farming for its real contribution to the socio-economic development. The results presented are compilation of physical and chemical parameters series measured in fish ponds and inquiries led in 2010-2014 to the fish farmers in seven provinces （40% of the total area of the country）. Weak values of some physical and chemical parameters showed that the majority of ponds are badly maintained. Thus, the dissolved oxygen values varied between 0.2 mg/L and 3.5 mg/L. The high relinquishment rate of the fish fanning （between 40% and 67% according to the provinces） could be explained by many constraints： no centers of fish farming breeding for various fish species and no production center of complete foods with local sub-products. About 75% of fish famers confirmed that they have never benefited framing in fish fanning. In spite of the diverse constraints, Burundi has a dense rivers system with favorable physical and chemical parameters and many appropriate sites for the fish farming. Thus, the main suggestions concern the sector reorganization.

Response of Seasonal Vegetation Dynamics to Climatic Constraints in Northeastern Burundi

The climate crises in East Africa (EA), particularly in Burundi, have affected vegetation which, in turn, plays a key role in the climate system by modifying the terrestrial water and energy balance. Consequently, it is vital to understand vegetation dynamics and its response to current and projected climate conditions to support the design of climate resilient land management strategies. The objective of this study was to study the dynamics of vegetation cover over the Northeastern Burundi (NEB) in response to climatic constraints. The methodology used consisted of the interpretation of satellite images along with the analysis of data collected through rain-gauge stations. The data sets used include time series composite moderate resolution imaging spectroradiometer (MODIS) normalized difference vegetation index (NDVI) data collected between February 2000 and December 2017;long term (1986-2017) rainfall data acquired from two meteorological stations throughout the Northeastern provinces in Burundi and precipitation and mean temperature data (1986-2017) from Climate Hazards Group InfraRed Precipitation with Station data (CHIRPS) and ERA5 Daily aggregates for the study area. The study provides an assessment of the vegetation trends in NEB using the NDVI time series. In addition, regression analysis is applied to assess the relations between NDVI and precipitation, air temperature, potential evapotranspiration, as well as with growing season characteristics (onset, cessation, and length). Results show that the rate in vegetation productivity is persistently gradual between 2000 and 2011 despite fluctuations from the mean position, followed by a lower growth rate over the period 2011-2017. There has been trend variation in precipitation, neither the temperature was constant. The temperature over the region has increased while the precipitation has decreased. The onset of the growing season and air temperature also show a significant influence on seasonal vegetation dynamics in the region. Drought-induced plant stress observed at the onset of the rainy season was the most important contributor to the subsequent less greening of vegetation especially over the area near the northern lakes.

Inequalities for Scalar Curvature and Shape Operator of an R-Lightlike Submanifold in Semi-Riemannian Manifold

We establish the links between the lightlike geometry and basics invariants of the associated semi-Riemannian geometry on r-lightlike submanifold and semi-Riemannian constructed from a semi-Riemannian ambient. Then we establish some basic inequalities, involving the scalar curvature and shape operator on r-lightlike coisotropic submanifold in semi-Riemannian manifold. Equality cases are also discussed.

Non Ideal Schottky Barrier Diode’s Parameters Extraction and Materials Identification from Dark I-V-T Characteristics

Several parameters of a commercial Si-based Schottky barrier diode (SBD) with unknown metal material and semiconductor-type have been investigated in this work from dark forward and reverse I-V characteristics in the temperature (T) range of [274.5 K - 366.5 K]. Those parameters include the reverse saturation current (Is), the ideality factor (n), the series and the shunt resistances (Rs and Rsh), the effective and the zero bias barrier heights (ΦB and ΦB0), the product of the electrical active area (A) and the effective Richardson constant (A**), the built-in potential (Vbi), together with the semiconductor doping concentration (NA or ND). Some of them have been extracted by using two or three different methods. The main features of each approach have been clearly stated. From one parameter to another, results have been discussed in terms of structure performance, comparison on one another when extracted from different methods, accordance or discordance with data from other works, and parameter’s temperature or voltage dependence. A comparison of results on ΦB, ΦB0, n and NA or ND parameters with some available data in literature for the same parameters, has especially led to clear propositions on the identity of the analyzed SBD’s metal and semiconductor-type.