This review explores the research activities surrounding the development and integration of smart electricity grids in Burkina Faso, a landlocked and arid territory in West Africa and one of the poorest countries in t...This review explores the research activities surrounding the development and integration of smart electricity grids in Burkina Faso, a landlocked and arid territory in West Africa and one of the poorest countries in the world with significant energy challenges. It examines the current state of energy infrastructure in Burkina Faso, focusing on the integration of renewable energy sources, particularly solar photovoltaics. It highlights the role of smart grid technologies in enabling the efficient integration of renewable energy, improving grid stability and facilitating rural electrification. Additionally, the review addresses key challenges such as inadequate infrastructure, regulatory gaps and financial constraints that hinder the deployment of smart grids in the country. By analysing existing research and ongoing projects, this paper provides a comprehensive overview of the opportunities and barriers to implementing a smart electricity grid in Burkina Faso and offers recommendations for future development and policy frameworks.展开更多
In this study,we simulated the thermal behavior of the mud-brick walls of a Nubian vault.We used EnergyPlus software for the simulation.The results obtained showed that the indoor temperature varies from 25.5℃ to 26....In this study,we simulated the thermal behavior of the mud-brick walls of a Nubian vault.We used EnergyPlus software for the simulation.The results obtained showed that the indoor temperature varies from 25.5℃ to 26.5℃ for the period of January 2018.It varies from 33.2℃ to 33.6℃ with an average value of 33.1℃ for the month of April 2018.For the period of July 2018,it varies from 30.3℃ to 32.2℃ with an average value of 31.2℃..Relative humidity for the period of July ranged from 62.3%to 73.5%,with an average value of 67.9%.The simulation enabled us to compare simulated and measured temperature and humidity values.We found that the level of thermal comfort in the Nubian vault is acceptable in both cool and hot periods.In view of these results,we can say that the Nubian vault is an architecture suited to our climate.The technical concept of the Nubian vault is adapted to the climatic conditions and traditional know-how of the Sahel.We also found that the use of raw earth,a locally available material,and the Nubian vault architectural process,contribute to thermal comfort and a reappropriation of local and adapted know-how.展开更多
In this paper, deterministic and stochastic models for schistosomiasis involving four sub-populations are developed. Conditions are given under which system exhibits thresholds behavior. The disease-free equilibrium i...In this paper, deterministic and stochastic models for schistosomiasis involving four sub-populations are developed. Conditions are given under which system exhibits thresholds behavior. The disease-free equilibrium is globally asymptotically stable if R0 ?and the unique endemic equilibrium is globally asymptotically stable when R0 >?1. The populations are computationally simulated under various conditions. Comparisons are made between the deterministic and the stochastic model.展开更多
This work is interested in solving the complex problem of understanding mass transfers in biological media. The contribution of the initial sample size is taken into account. Transfers are established more efficiently...This work is interested in solving the complex problem of understanding mass transfers in biological media. The contribution of the initial sample size is taken into account. Transfers are established more efficiently in small samples. Thus, from the first 50 minutes, the cubic sample at 1 cm stop is already at 50% while the sample at 4 cm edge is at about 90% of its initial water content. Likewise the shape is combined with the size. But it is revealed that if we fix similar characteristic dimensions, we can bypass the notion of initial shape. Thus the cubic samples 4 cm of edges. 4 cm diameter of spherical shape, 4 cm × 4 cm height-diameter cylindrical one, all dry identically.展开更多
When the circuit breaker cuts the electric current, an electric arc is created between its electrodes. The success or failure of breaking the electric current by the circuit breaker depends strongly on the physico-che...When the circuit breaker cuts the electric current, an electric arc is created between its electrodes. The success or failure of breaking the electric current by the circuit breaker depends strongly on the physico-chemical properties of the electric arc created, such as the composition of which depends on the material of the electrical contacts. In this work, we determine the equilibrium composition of the electric arc in the low voltage air circuit breaker with silver tin dioxide alloy contacts, in a temperature range from 500 K to 15,000 K and at atmospheric pressure. We use the Gibbs free energy minimization method and develop a computer code to determine the equilibrium composition of the created plasma. The analysis of the results obtained shows that O<sub>2</sub> particles with a dissociation energy of 5.114 eV, NO with a dissociation energy of 6.503 eV, and N<sub>2</sub> dissociation 9.756 eV dissociate around 3500 K, 5000 K, and 7500 K, respectively. We note that the electro-neutrality is established between the electrons and the cations: Ag<sup>+</sup> and NO<sup>+</sup>, for temperatures lower than 6500 K. For temperatures higher than 6500 K, the electro-neutrality is established between the electrons and the cations: N<sup>+</sup>, O<sup>+</sup>, and Ag<sup>+</sup>. The numerical density of the electrons increases when the proportion of the vapor of the electrical contacts increases in the mixture, in particular for temperatures lower than 11,000 K.展开更多
Telegraph equations are derived from the equations of transmission line theory. They describe the relationships between the currents and voltages on a portion of an electric line as a function of the linear constants ...Telegraph equations are derived from the equations of transmission line theory. They describe the relationships between the currents and voltages on a portion of an electric line as a function of the linear constants of the conductor (resistance, conductance, inductance, capacitance). Their resolution makes it possible to determine the variation of the current and the voltage as a function of time at each point of the line. By adopting a general sinusoidal form, we propose a new exact solution to the telegraphers’ partial differential equations. Different simulations have been carried out considering the parameter of the 12/20 (24) kV Medium Voltage Cable NF C 33,220. The curves of the obtained solution better fit the real voltage curves observed in the electrical networks in operation.展开更多
Fine unsaturated soils are used in many applications, particularly in road infrastructure and in construction. These materials undergo deformations according to the stresses to which they are subjected. The purpose of...Fine unsaturated soils are used in many applications, particularly in road infrastructure and in construction. These materials undergo deformations according to the stresses to which they are subjected. The purpose of this paper is to study the influence of hydromechanical stresses on the behavior of low swelling soils compacted at low water content in accordance with the French standard GTR 92 (Guide des Terrassements Routiers). Then, various experimental tests on an oedometer were carried out in the laboratory. Two types of low swelling soil sampled in Nasso on the outskirts of the town of Bobo Dioulasso (Burkina Faso) were used. After shuffling, each sample was moistened to its optimum water content and then compacted to 90% and 95% of its optimum density. Behavior tests show that these soils deform very little when subjected to hydromechanical stresses. However, these deformations are swelling in nature for low mechanical stresses and when the stresses are high, they tend to collapse. When these soils are subjected to a vertical stress of 420 kPa, the primary consolidation time is of the order of one minute for NH<sub>2</sub> (a silty soil) and about ten minutes for NH<sub>3 </sub>(a silty-clayed soil).展开更多
This paper concerns the calculation of equilibrium composition of plasma mixture Air Fe<sub>2</sub>O<sub>3</sub>, SiO<sub>2</sub>, Al<sub>2</sub>O<sub>3</sub>...This paper concerns the calculation of equilibrium composition of plasma mixture Air Fe<sub>2</sub>O<sub>3</sub>, SiO<sub>2</sub>, Al<sub>2</sub>O<sub>3</sub> and CO in temperatures range 1000 K to 6000 K. We supposed that the plasma is at atmospheric pressure and at local thermodynamic equilibrium (ETL). In the Saharan zone, the aerosols are proven from desert dust and biomass fires. They are essentially composed of oxides of silicon, calcium, iron, aluminum and carbonaceous elements from biomass. Thus, air circuit breakers often operate in a polluted environment without specific protection. They can have abnormal behaviors and failures of cuts. We used Gibbs free energy minimization method to access the different numerical densities of chemical species as a function of temperature. These data are very important to calculate thermodynamic properties, transport coefficients and modeling electrical arc in circuit breakers. The results show that the dust brings many particles which have low dissociation and ionization energies. This leads to an increase in metallic elements and a strong increase in the numerical density of electrons which could have a detrimental effect during the current cut-off phase with the increase in the electrical conductivity of the plasma.展开更多
Thallium is a heavy metal highly toxic to the biosphere. It can be determined by anodic stripping voltammetry after deposition on mercury film. The aim of this work is to study the conditions and mechanisms of deposit...Thallium is a heavy metal highly toxic to the biosphere. It can be determined by anodic stripping voltammetry after deposition on mercury film. The aim of this work is to study the conditions and mechanisms of deposition of Hg on glassy carbon electrode and Tl on Hg film by cyclic voltammetry, scanning electron microscopy, chronoamperometry and impedance techniques. The results showed a germination and growth of a 3D Hg phase on glassy carbon electrode. Similarly, the electrodeposition of Tl on Hg follows a 3D three-dimensional nucleation with diffusion controlled growth. The impedance measurements reveal an easier charge transfer on the Tl film.展开更多
Background: Fractures in the limbs of racehorses are common, resulting among other factors, as the result of repeated ground reaction forces on bones and joints, leading to catastrophic failure. Aim: To quantify groun...Background: Fractures in the limbs of racehorses are common, resulting among other factors, as the result of repeated ground reaction forces on bones and joints, leading to catastrophic failure. Aim: To quantify ground impact transmission through the limb bones of un-shod healthy horses using the non-invasive technique of acoustic myography (AMG). Methods: Four sites were selected for AMG measurements at the walk and trot, hoof wall (site 1) and sites 2 - 4, metacarpal 3, carpals and the radius of the left forelimb of two healthy horses. Measurements were on both rubber and concrete. AMG of the equine hind limb suspensory system was made and analyzed (amplitude and timing) for the proximal suspensory ligament (PSL) and the SDFT/DDFT. Results: AMG signal amplitude at site 1 (1.5 ± 0.2 versus 1.1 ± 1.5) was not found to be significantly different at the trot compared to the walk;however, sites 2, 3 and 4 were all significantly different when compared between the two gaits;site 2 P = 0.008;site 3 P = 0.006;site 4 P = 0.005. AMG signals recorded on the rubber surface had smaller amplitude than the equivalent signal and site on the concrete surface. Ground Reaction Force (GRF) transmission in the equine forelimb was 22 m/sec, whilst that of the hind limb suspensory system was 25 m/sec. Conclusion: Findings indicate that GRFs are transmitted proximally along the limb at considerable speeds, that they are dampened by tissues and structures in the limb, and that the GRFs are present and detectable proximal to the fetlock joint.展开更多
Photovoltaic solar energy is still in its infancy in Burkina Faso, despite the country’s high solar potential. The electricity grid is experiencing an increase in demand for energy, creating a shortfall in supply. Th...Photovoltaic solar energy is still in its infancy in Burkina Faso, despite the country’s high solar potential. The electricity grid is experiencing an increase in demand for energy, creating a shortfall in supply. The Zagtouli photovoltaic solar power plant in Burkina Faso is the first milestone in the development of renewable photovoltaic energy, with a rated output of 33.6 Megawatts peak, to strengthen the electricity grid by reducing hydrocarbon consumption. The aim of this work is to evaluate the performance of the plant by proposing a performance score for the Zagtouli plant, which should provide a basis for assessing the performance of a power plant. To meet the objectives, we collected data for three consecutive years of production, from 2019 to 2021. From this data, we used the method based on the calculation of the performance indicators specified by the International Energy Agency (IEA) and described in the standardised norms IEC (International Electrotechnical Commission) CEI61724, and we also carried out a performance classification using the K-Means method. It is clear that with the results obtained for the PR performance index (over 70%), the installation can be classified as one of the best-performing systems. It also emerges that various losses (temperatures on the panels, cabling, partial shading, spectral losses, dirt, and unexpected inverter failures) have a negative impact on the installation’s energy production.展开更多
Residential photovoltaic (PV) systems connected to the grid are used for self-consumption. Any surplus production is fed into the grid and contributes to improving the voltage. Several techniques are developed to mode...Residential photovoltaic (PV) systems connected to the grid are used for self-consumption. Any surplus production is fed into the grid and contributes to improving the voltage. Several techniques are developed to model their connection. However, studies on methods of injecting energy production into the Low Voltage (LV) network are nowadays a problem. This paper proposes a mathematical model to determine the current to be injected and calculate each node’s voltage. The current equation is a recurrence relation with an initial condition. This initial condition is for the case of a single PV system connected to the LV grid. The equation can also be written in matrix form. Similarly, the voltage solution is a recurrence relation. It also has an initial condition for the first node. Both mathematical formulae with the proposed initial conditions are consistent and can be used for the determination of the current and voltage of the different nodes in the grid.展开更多
One of the major problems associated with the therapeutic application of β-lactam antibiotics is their significant instability [1]-[3]. Analogs from that group are easily degraded in aqueous solutions and in solid st...One of the major problems associated with the therapeutic application of β-lactam antibiotics is their significant instability [1]-[3]. Analogs from that group are easily degraded in aqueous solutions and in solid state, which happens predominantly as a result of β-lactam ring chemical degradation. Because of this, the chemical integrity of β-lactam antibiotics must be closely monitored to meet FDA requirements. The original iodometric method based on visual detection of the end products of beta-lactamase hydrolysis that has been used to test beta-lactamase activity [4] was modified to quantitatively assess the amount of degraded product in amoxicillin. A UV-visible spectrophotometric method has been used, focusing on the ability of the products from the degradation of β-lactam analogs to absorb iodine from bulk solution, resulting in a significant reduction in the absorption spectra. Amoxicillin trihydrate tablets with different expiration dates and amoxicillin samples pre-loaded with known amounts of degraded amoxicillin have been used to generate a calibration curve and quantify the presence of degraded materials. Results show that the changes in the absorption spectra of iodine reagent directly correlate with the fraction of degraded β-lactam antibiotics, such as amoxicillin, in commercial products. The proposed assay might be as close as one step from simpler and cheaper methods of quantitative analysis of degraded β-lactam analogs, with estimated sensitivity in the range of 1% - 2%, which is better than the current FDA requirements.展开更多
An experimental study for the drying kinetics of whole okra was carried out. In the study, different ages were considered by taking into account influence of okra maturity on its convective drying. The 2D moisture evo...An experimental study for the drying kinetics of whole okra was carried out. In the study, different ages were considered by taking into account influence of okra maturity on its convective drying. The 2D moisture evolution inside the product and its maturity were evaluated by fitting experimental data versus drying time. The water effective diffusion coefficient of okra at different maturity states was gotten by the experimental model using Fick’s second law. A parametric study was carried out in the ranging of okra age from 2 to 7 days at 60℃, both fruits gathered on the same plant to avoid divergences due to okra varieties that can induce difference on physical structure and the chemical composition. It was found from the experimental results that okra maturity has important influence on its behaviour during convective drying. At 2, 3, 4, 5 and 7 days old, the drying effective time was respectively 780, 1000, 1155, 850 and 750 min. Effective diffusivity of the okra in this order of age was 1.38 × 10-10, 6.09 × 10-11, 1.23 × 10-11, 8.98 × 10-11, and 1.05 × 10-10 m2/s in the present study, while the average initial moisture content was respectively 12.27, 9.00, 7.53, 5.97 and 4.92 Kgw/Kgdm.展开更多
The case describes the situation of a Brazilian accounting courses in undergraduate programmes middle-class family, as an alternative to teach introductory In its solution, it was used an accounting system, adapted to...The case describes the situation of a Brazilian accounting courses in undergraduate programmes middle-class family, as an alternative to teach introductory In its solution, it was used an accounting system, adapted to the needs of register, control, and information of the family equity, through the application of the content of introductory accounting. The authors aim to offer a didactic and playful alternative for the teaching of introductory accounting in undergraduation courses, such as business management, accountancy, economy, and others in which this course is offered. The aim is to show the integration of accounting contents offered in the course, applied to the most common and nearest experience of freshmen in their first year during the undergraduate program： the family. The case can be solved in two phases： In the first, during a class of up to 100 minutes, the professor develops six activities, culminating in the students answering up to four suggested questions; in the second, whose application is left to the professor, in another class further ahead, is numerical.展开更多
Information and communication technology （ICT） and systems are essential for every business. They can be used in retail, manufacturing and other industries. Nevertheless, new and innovative ideas and solutions are c...Information and communication technology （ICT） and systems are essential for every business. They can be used in retail, manufacturing and other industries. Nevertheless, new and innovative ideas and solutions are constantly emerging and introducing new possibilities for the reorganization of traditional logistics processes. Particularly, attention is given to basic concept of CC （cloud computing） service models and opportunities in logistics. This paper provides comprehensive review and comparison of different ICT solutions and CC applications. As a new and cutting-edge technology, CC is changing the form and function of information technology infrastructures making supply chain information collaboration easy and feasible. It can also be an enabler of fully electronic logistics management systems. Adoption of CC concept involves strong hardware support, good internet connectivity and implied reorganization of traditional business activities.展开更多
The study focuses on estimating the input power of a power plant from available data, using the theoretical inverter efficiency as the key parameter. The paper addresses the problem of missing data in power generation...The study focuses on estimating the input power of a power plant from available data, using the theoretical inverter efficiency as the key parameter. The paper addresses the problem of missing data in power generation systems and proposes an approach based on the efficiency formula widely documented in the literature. In the absence of input data, this method makes it possible to estimate the plant’s input power using data extracted from the site, in particular that provided by the Ministry of the Environment. The importance of this study lies in the need to accurately determine the input power in order to assess the overall performance of the energy system.展开更多
Living in a habitat with comfort is requested by all. Cinder block bricks have poor thermal properties, leading people to use fan heaters and air conditioners to regain comfort. To overcome this problem of thermal dis...Living in a habitat with comfort is requested by all. Cinder block bricks have poor thermal properties, leading people to use fan heaters and air conditioners to regain comfort. To overcome this problem of thermal discomfort in buildings, we used lightweight concrete such as foamed concrete which is a material that has improved thermal properties for thermal comfort. In addition, this material was compared with local materials used for the construction of buildings such as BTC, adobe and BLT mixed with binders. The results showed that foamed concrete is a material that has good thermal and mechanical properties compared to local materials mixed with binders. The foamed concrete having acceptable thermo-mechanical properties was that having a density of 930 kg/m<sup>3</sup>. It has a thermal resistance of 0.4 m<sup>2</sup>·K/W for a thickness of 20 cm. The foamed concrete having acceptable thermo-mechanical properties was that having a density of 930 kg/m3</sup>. It has a thermal resistance of 0.4 m2</sup>·K/W for a thickness of 20 cm. For sunshine on a daily cycle equal to 12 hours, the characteristic thickness achieved by this material is 7.29 cm. It also has a shallow depth of heat diffusion having a lower thickness than other materials. This shows that foamed concrete is a promising material for the construction of buildings.展开更多
In this paper, we present a study on the prediction of the power produced by the 33 MWp photovoltaic power plant at Zagtouli in Burkina-Faso, as a function of climatic factors. We identified models in the literature, ...In this paper, we present a study on the prediction of the power produced by the 33 MWp photovoltaic power plant at Zagtouli in Burkina-Faso, as a function of climatic factors. We identified models in the literature, namely the Benchmark, input/output, Marion, Cristo-fri, Kroposki, Jones-Underwood and Hatziargyriou prediction models, which depend exclusively on environmental parameters. We then compared our linear model with these seven mathematical models in order to determine the most optimal prediction model. Our results show that the Hatziargyriou model is better in terms of accuracy for power prediction.展开更多
文摘This review explores the research activities surrounding the development and integration of smart electricity grids in Burkina Faso, a landlocked and arid territory in West Africa and one of the poorest countries in the world with significant energy challenges. It examines the current state of energy infrastructure in Burkina Faso, focusing on the integration of renewable energy sources, particularly solar photovoltaics. It highlights the role of smart grid technologies in enabling the efficient integration of renewable energy, improving grid stability and facilitating rural electrification. Additionally, the review addresses key challenges such as inadequate infrastructure, regulatory gaps and financial constraints that hinder the deployment of smart grids in the country. By analysing existing research and ongoing projects, this paper provides a comprehensive overview of the opportunities and barriers to implementing a smart electricity grid in Burkina Faso and offers recommendations for future development and policy frameworks.
文摘In this study,we simulated the thermal behavior of the mud-brick walls of a Nubian vault.We used EnergyPlus software for the simulation.The results obtained showed that the indoor temperature varies from 25.5℃ to 26.5℃ for the period of January 2018.It varies from 33.2℃ to 33.6℃ with an average value of 33.1℃ for the month of April 2018.For the period of July 2018,it varies from 30.3℃ to 32.2℃ with an average value of 31.2℃..Relative humidity for the period of July ranged from 62.3%to 73.5%,with an average value of 67.9%.The simulation enabled us to compare simulated and measured temperature and humidity values.We found that the level of thermal comfort in the Nubian vault is acceptable in both cool and hot periods.In view of these results,we can say that the Nubian vault is an architecture suited to our climate.The technical concept of the Nubian vault is adapted to the climatic conditions and traditional know-how of the Sahel.We also found that the use of raw earth,a locally available material,and the Nubian vault architectural process,contribute to thermal comfort and a reappropriation of local and adapted know-how.
文摘In this paper, deterministic and stochastic models for schistosomiasis involving four sub-populations are developed. Conditions are given under which system exhibits thresholds behavior. The disease-free equilibrium is globally asymptotically stable if R0 ?and the unique endemic equilibrium is globally asymptotically stable when R0 >?1. The populations are computationally simulated under various conditions. Comparisons are made between the deterministic and the stochastic model.
文摘This work is interested in solving the complex problem of understanding mass transfers in biological media. The contribution of the initial sample size is taken into account. Transfers are established more efficiently in small samples. Thus, from the first 50 minutes, the cubic sample at 1 cm stop is already at 50% while the sample at 4 cm edge is at about 90% of its initial water content. Likewise the shape is combined with the size. But it is revealed that if we fix similar characteristic dimensions, we can bypass the notion of initial shape. Thus the cubic samples 4 cm of edges. 4 cm diameter of spherical shape, 4 cm × 4 cm height-diameter cylindrical one, all dry identically.
文摘When the circuit breaker cuts the electric current, an electric arc is created between its electrodes. The success or failure of breaking the electric current by the circuit breaker depends strongly on the physico-chemical properties of the electric arc created, such as the composition of which depends on the material of the electrical contacts. In this work, we determine the equilibrium composition of the electric arc in the low voltage air circuit breaker with silver tin dioxide alloy contacts, in a temperature range from 500 K to 15,000 K and at atmospheric pressure. We use the Gibbs free energy minimization method and develop a computer code to determine the equilibrium composition of the created plasma. The analysis of the results obtained shows that O<sub>2</sub> particles with a dissociation energy of 5.114 eV, NO with a dissociation energy of 6.503 eV, and N<sub>2</sub> dissociation 9.756 eV dissociate around 3500 K, 5000 K, and 7500 K, respectively. We note that the electro-neutrality is established between the electrons and the cations: Ag<sup>+</sup> and NO<sup>+</sup>, for temperatures lower than 6500 K. For temperatures higher than 6500 K, the electro-neutrality is established between the electrons and the cations: N<sup>+</sup>, O<sup>+</sup>, and Ag<sup>+</sup>. The numerical density of the electrons increases when the proportion of the vapor of the electrical contacts increases in the mixture, in particular for temperatures lower than 11,000 K.
文摘Telegraph equations are derived from the equations of transmission line theory. They describe the relationships between the currents and voltages on a portion of an electric line as a function of the linear constants of the conductor (resistance, conductance, inductance, capacitance). Their resolution makes it possible to determine the variation of the current and the voltage as a function of time at each point of the line. By adopting a general sinusoidal form, we propose a new exact solution to the telegraphers’ partial differential equations. Different simulations have been carried out considering the parameter of the 12/20 (24) kV Medium Voltage Cable NF C 33,220. The curves of the obtained solution better fit the real voltage curves observed in the electrical networks in operation.
文摘Fine unsaturated soils are used in many applications, particularly in road infrastructure and in construction. These materials undergo deformations according to the stresses to which they are subjected. The purpose of this paper is to study the influence of hydromechanical stresses on the behavior of low swelling soils compacted at low water content in accordance with the French standard GTR 92 (Guide des Terrassements Routiers). Then, various experimental tests on an oedometer were carried out in the laboratory. Two types of low swelling soil sampled in Nasso on the outskirts of the town of Bobo Dioulasso (Burkina Faso) were used. After shuffling, each sample was moistened to its optimum water content and then compacted to 90% and 95% of its optimum density. Behavior tests show that these soils deform very little when subjected to hydromechanical stresses. However, these deformations are swelling in nature for low mechanical stresses and when the stresses are high, they tend to collapse. When these soils are subjected to a vertical stress of 420 kPa, the primary consolidation time is of the order of one minute for NH<sub>2</sub> (a silty soil) and about ten minutes for NH<sub>3 </sub>(a silty-clayed soil).
文摘This paper concerns the calculation of equilibrium composition of plasma mixture Air Fe<sub>2</sub>O<sub>3</sub>, SiO<sub>2</sub>, Al<sub>2</sub>O<sub>3</sub> and CO in temperatures range 1000 K to 6000 K. We supposed that the plasma is at atmospheric pressure and at local thermodynamic equilibrium (ETL). In the Saharan zone, the aerosols are proven from desert dust and biomass fires. They are essentially composed of oxides of silicon, calcium, iron, aluminum and carbonaceous elements from biomass. Thus, air circuit breakers often operate in a polluted environment without specific protection. They can have abnormal behaviors and failures of cuts. We used Gibbs free energy minimization method to access the different numerical densities of chemical species as a function of temperature. These data are very important to calculate thermodynamic properties, transport coefficients and modeling electrical arc in circuit breakers. The results show that the dust brings many particles which have low dissociation and ionization energies. This leads to an increase in metallic elements and a strong increase in the numerical density of electrons which could have a detrimental effect during the current cut-off phase with the increase in the electrical conductivity of the plasma.
文摘Thallium is a heavy metal highly toxic to the biosphere. It can be determined by anodic stripping voltammetry after deposition on mercury film. The aim of this work is to study the conditions and mechanisms of deposition of Hg on glassy carbon electrode and Tl on Hg film by cyclic voltammetry, scanning electron microscopy, chronoamperometry and impedance techniques. The results showed a germination and growth of a 3D Hg phase on glassy carbon electrode. Similarly, the electrodeposition of Tl on Hg follows a 3D three-dimensional nucleation with diffusion controlled growth. The impedance measurements reveal an easier charge transfer on the Tl film.
文摘Background: Fractures in the limbs of racehorses are common, resulting among other factors, as the result of repeated ground reaction forces on bones and joints, leading to catastrophic failure. Aim: To quantify ground impact transmission through the limb bones of un-shod healthy horses using the non-invasive technique of acoustic myography (AMG). Methods: Four sites were selected for AMG measurements at the walk and trot, hoof wall (site 1) and sites 2 - 4, metacarpal 3, carpals and the radius of the left forelimb of two healthy horses. Measurements were on both rubber and concrete. AMG of the equine hind limb suspensory system was made and analyzed (amplitude and timing) for the proximal suspensory ligament (PSL) and the SDFT/DDFT. Results: AMG signal amplitude at site 1 (1.5 ± 0.2 versus 1.1 ± 1.5) was not found to be significantly different at the trot compared to the walk;however, sites 2, 3 and 4 were all significantly different when compared between the two gaits;site 2 P = 0.008;site 3 P = 0.006;site 4 P = 0.005. AMG signals recorded on the rubber surface had smaller amplitude than the equivalent signal and site on the concrete surface. Ground Reaction Force (GRF) transmission in the equine forelimb was 22 m/sec, whilst that of the hind limb suspensory system was 25 m/sec. Conclusion: Findings indicate that GRFs are transmitted proximally along the limb at considerable speeds, that they are dampened by tissues and structures in the limb, and that the GRFs are present and detectable proximal to the fetlock joint.
文摘Photovoltaic solar energy is still in its infancy in Burkina Faso, despite the country’s high solar potential. The electricity grid is experiencing an increase in demand for energy, creating a shortfall in supply. The Zagtouli photovoltaic solar power plant in Burkina Faso is the first milestone in the development of renewable photovoltaic energy, with a rated output of 33.6 Megawatts peak, to strengthen the electricity grid by reducing hydrocarbon consumption. The aim of this work is to evaluate the performance of the plant by proposing a performance score for the Zagtouli plant, which should provide a basis for assessing the performance of a power plant. To meet the objectives, we collected data for three consecutive years of production, from 2019 to 2021. From this data, we used the method based on the calculation of the performance indicators specified by the International Energy Agency (IEA) and described in the standardised norms IEC (International Electrotechnical Commission) CEI61724, and we also carried out a performance classification using the K-Means method. It is clear that with the results obtained for the PR performance index (over 70%), the installation can be classified as one of the best-performing systems. It also emerges that various losses (temperatures on the panels, cabling, partial shading, spectral losses, dirt, and unexpected inverter failures) have a negative impact on the installation’s energy production.
文摘Residential photovoltaic (PV) systems connected to the grid are used for self-consumption. Any surplus production is fed into the grid and contributes to improving the voltage. Several techniques are developed to model their connection. However, studies on methods of injecting energy production into the Low Voltage (LV) network are nowadays a problem. This paper proposes a mathematical model to determine the current to be injected and calculate each node’s voltage. The current equation is a recurrence relation with an initial condition. This initial condition is for the case of a single PV system connected to the LV grid. The equation can also be written in matrix form. Similarly, the voltage solution is a recurrence relation. It also has an initial condition for the first node. Both mathematical formulae with the proposed initial conditions are consistent and can be used for the determination of the current and voltage of the different nodes in the grid.
文摘One of the major problems associated with the therapeutic application of β-lactam antibiotics is their significant instability [1]-[3]. Analogs from that group are easily degraded in aqueous solutions and in solid state, which happens predominantly as a result of β-lactam ring chemical degradation. Because of this, the chemical integrity of β-lactam antibiotics must be closely monitored to meet FDA requirements. The original iodometric method based on visual detection of the end products of beta-lactamase hydrolysis that has been used to test beta-lactamase activity [4] was modified to quantitatively assess the amount of degraded product in amoxicillin. A UV-visible spectrophotometric method has been used, focusing on the ability of the products from the degradation of β-lactam analogs to absorb iodine from bulk solution, resulting in a significant reduction in the absorption spectra. Amoxicillin trihydrate tablets with different expiration dates and amoxicillin samples pre-loaded with known amounts of degraded amoxicillin have been used to generate a calibration curve and quantify the presence of degraded materials. Results show that the changes in the absorption spectra of iodine reagent directly correlate with the fraction of degraded β-lactam antibiotics, such as amoxicillin, in commercial products. The proposed assay might be as close as one step from simpler and cheaper methods of quantitative analysis of degraded β-lactam analogs, with estimated sensitivity in the range of 1% - 2%, which is better than the current FDA requirements.
文摘An experimental study for the drying kinetics of whole okra was carried out. In the study, different ages were considered by taking into account influence of okra maturity on its convective drying. The 2D moisture evolution inside the product and its maturity were evaluated by fitting experimental data versus drying time. The water effective diffusion coefficient of okra at different maturity states was gotten by the experimental model using Fick’s second law. A parametric study was carried out in the ranging of okra age from 2 to 7 days at 60℃, both fruits gathered on the same plant to avoid divergences due to okra varieties that can induce difference on physical structure and the chemical composition. It was found from the experimental results that okra maturity has important influence on its behaviour during convective drying. At 2, 3, 4, 5 and 7 days old, the drying effective time was respectively 780, 1000, 1155, 850 and 750 min. Effective diffusivity of the okra in this order of age was 1.38 × 10-10, 6.09 × 10-11, 1.23 × 10-11, 8.98 × 10-11, and 1.05 × 10-10 m2/s in the present study, while the average initial moisture content was respectively 12.27, 9.00, 7.53, 5.97 and 4.92 Kgw/Kgdm.
文摘The case describes the situation of a Brazilian accounting courses in undergraduate programmes middle-class family, as an alternative to teach introductory In its solution, it was used an accounting system, adapted to the needs of register, control, and information of the family equity, through the application of the content of introductory accounting. The authors aim to offer a didactic and playful alternative for the teaching of introductory accounting in undergraduation courses, such as business management, accountancy, economy, and others in which this course is offered. The aim is to show the integration of accounting contents offered in the course, applied to the most common and nearest experience of freshmen in their first year during the undergraduate program： the family. The case can be solved in two phases： In the first, during a class of up to 100 minutes, the professor develops six activities, culminating in the students answering up to four suggested questions; in the second, whose application is left to the professor, in another class further ahead, is numerical.
文摘Information and communication technology （ICT） and systems are essential for every business. They can be used in retail, manufacturing and other industries. Nevertheless, new and innovative ideas and solutions are constantly emerging and introducing new possibilities for the reorganization of traditional logistics processes. Particularly, attention is given to basic concept of CC （cloud computing） service models and opportunities in logistics. This paper provides comprehensive review and comparison of different ICT solutions and CC applications. As a new and cutting-edge technology, CC is changing the form and function of information technology infrastructures making supply chain information collaboration easy and feasible. It can also be an enabler of fully electronic logistics management systems. Adoption of CC concept involves strong hardware support, good internet connectivity and implied reorganization of traditional business activities.
文摘The study focuses on estimating the input power of a power plant from available data, using the theoretical inverter efficiency as the key parameter. The paper addresses the problem of missing data in power generation systems and proposes an approach based on the efficiency formula widely documented in the literature. In the absence of input data, this method makes it possible to estimate the plant’s input power using data extracted from the site, in particular that provided by the Ministry of the Environment. The importance of this study lies in the need to accurately determine the input power in order to assess the overall performance of the energy system.
文摘Living in a habitat with comfort is requested by all. Cinder block bricks have poor thermal properties, leading people to use fan heaters and air conditioners to regain comfort. To overcome this problem of thermal discomfort in buildings, we used lightweight concrete such as foamed concrete which is a material that has improved thermal properties for thermal comfort. In addition, this material was compared with local materials used for the construction of buildings such as BTC, adobe and BLT mixed with binders. The results showed that foamed concrete is a material that has good thermal and mechanical properties compared to local materials mixed with binders. The foamed concrete having acceptable thermo-mechanical properties was that having a density of 930 kg/m<sup>3</sup>. It has a thermal resistance of 0.4 m<sup>2</sup>·K/W for a thickness of 20 cm. The foamed concrete having acceptable thermo-mechanical properties was that having a density of 930 kg/m3</sup>. It has a thermal resistance of 0.4 m2</sup>·K/W for a thickness of 20 cm. For sunshine on a daily cycle equal to 12 hours, the characteristic thickness achieved by this material is 7.29 cm. It also has a shallow depth of heat diffusion having a lower thickness than other materials. This shows that foamed concrete is a promising material for the construction of buildings.
文摘In this paper, we present a study on the prediction of the power produced by the 33 MWp photovoltaic power plant at Zagtouli in Burkina-Faso, as a function of climatic factors. We identified models in the literature, namely the Benchmark, input/output, Marion, Cristo-fri, Kroposki, Jones-Underwood and Hatziargyriou prediction models, which depend exclusively on environmental parameters. We then compared our linear model with these seven mathematical models in order to determine the most optimal prediction model. Our results show that the Hatziargyriou model is better in terms of accuracy for power prediction.
