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The investigation focused on the energy consumption of part of the refrigeration equipment of a food supply chain company based in France. The cold rooms concerned are used for fresh and frozen food. The objective of the audit is to verify and analyse the electricity consumption of the equipment and to propose sustainable solutions to improve the whole site. The requested energy audit concerned only two machine rooms (machine room 5 and 7). The study predicted an economic gain of up to €30,000/year from equipment maintenance and a significant reduction in environmental impact at this site. In addition, this energy audit identified additional areas for improvement in machine room 7 that could lead to supplementary energy savings of €16,600 and a potential reduction of 15 tonnes of CO2 emissions. Keywords: Energy efficiency, audit, preventive diagnosis, CO2 emissions, energy saving.

Purpose The purpose of this paper is to evaluate the wind energy potential of Mount Bamboutos in Cameroon by comparing nine numerical methods in determining Weibull parameters for the installation of a sustainable wind farm. Design/methodology/approach By using statistical analysis, the analysis of shape and scale parameters, the estimation of the available wind power density and wind direction frequency distributions, the objective of this paper is to compare nine numerical methods in estimating Weibull parameters for the installation of a sustainable wind farm in Mount Bamboutos, Cameroon. Findings The results suggested that the minimum and maximum values of the standard deviation occurred in the months of May and November 2016, respectively. The graphical method appeared to be the most effective method with the maximum value of variance and minimum values of chi-square and RMSE. The scale factor parameter values indicated that Mount Bamboutos hills were a potential site for electricity generation. The analysis of wind power density showed that it reached the maximum and minimum values in February and September, respectively. The wind direction frequency distributions showed that the prevailing wind directions were North-East. Originality/value The wind energy potential of Mount Bamboutos in Cameroon was performed by using nine numerical methods. Therefore, it could be effective to have a prediction model for the wind speed profile. The analysis of wind power density showed that it reached the maximum and minimum values in February and September, respectively. The wind direction frequency distributions showed that the prevailing wind directions were North-East.

Purpose This paper aims to investigate a linear and temporal stability analysis of hybrid nanofluid flow between two parallel plates filled with a porous medium and whose lower plate is fixed and the upper plate animated by a uniform rectilinear motion. Design/methodology/approach The nanofluid is composed of water as a regular fluid, silver (Ag) and alumina (Al2O3) as nanoparticles. The mathematical model takes into account other effects such as the magnetic field and the aspiration (injection/suction). Under the assumption of a low magnetic Reynolds number, a modified Orr–Sommerfeld-type eigenvalue differential equation governing flow stability was derived and solved numerically by Chebyshev’s spectral collocation method. The effects of parameters such as volume fraction, Darcy number, injection/suction Reynolds number, Hartmann number were analyzed. Findings It was found the following: the Darcy number affects the stability of the flow, the injection/suction Reynolds number has a negligible effect, the volume fraction damped disturbances and the magnetic field plays a very important role in enlarging the area of flow stability. Originality/value The originality of this work resides in the linear and temporal stability analysis of hydromagnetic Couette flow for hybrid nanofluid through porous media with small suction and injection effects.

Purpose For this purpose, a linear stability analysis based on the Navier–Stokes and Maxwell equations is made leading to an eigenvalue differential equation of the modified Orr–Sommerfeld type which is solved numerically by the spectral collocation method based on Chebyshev polynomials. Unlike previous studies, blood is considered as a non-Newtonian fluid. The effects of various parameters such as volume fraction of nanoparticles, Casson parameter, Darcy number, Hartmann number on flow stability were examined and presented. This paper aims to investigate a linear stability analysis of non-Newtonian blood flow with magnetic nanoparticles with an application to controlled drug delivery. Design/methodology/approach Targeted delivery of therapeutic agents such as stem cells and drugs using magnetic nanoparticles with the help of external magnetic fields is an emerging treatment modality for many diseases. To this end, controlling the movement of nanoparticles in the human body is of great importance. This study investigates controlled drug delivery by using magnetic nanoparticles in a porous artery under the influence of a magnetic field. Findings It was found the following: the Casson parameter affects the stability of the flow by amplifying the amplitude of the disturbance which reflects its destabilizing effect. It emerges from this study that the taking into account of the non-Newtonian character is essential in the modeling of such a system, and that the results can be very different from those obtained by supposing that the blood is a Newtonian fluid. The presence of iron oxide nanoparticles in the blood increases the inertia of the fluid, which dampens the disturbances. The Strouhal number has a stabilizing effect on the flow which makes it possible to say that the oscillating circulation mechanisms dampen the disturbances. The Darcy number affects the stability of the flow and has a stabilizing effect, which makes it possible to increase the contact surface between the nanoparticles and the fluid allowing very high heat transfer rates to be obtained. It also emerges from this study that the presence of the porosity prevents the sedimentation of the nanoparticles. By studying the effect of the magnetic field on the stability of the flow, it is observed that the Hartmann number keeps the flow completely stable. This allows saying that the magnetic field makes the dissipations very important because the kinetic energy of the electrically conductive ferrofluid is absorbed by the Lorentz force. Originality/value The originality of this paper resides on the application of the linear stability analysis for controlled drug delivery.

In this paper, a stability analysis of a hybrid nanofluid flow between two parallel and stationnary plates filled with a porous medium was investigated. The hybrid nanofluid is composed of water as regular fluid, copper ( Cu ) and alumina ( Al 2 O 3 ) as nanoparticles. A mathematical modeling of the problem was developed by taking account other effects such as aspiration (suction/injection) and magnetic field. An eigenvalue differential equation namely the modified Orr-Sommerfeld equation governing the stability of the flow was derived and solved numerically by spectral collocation method with expansions in Chebyshev polynomials. The effect of the density of particles, suction/injection Reynolds number, Hartmann number, Darcy number and volume fraction on the flow stability was examined and presented. It was found the following: the Darcy number affects the stability of the flow, the suction/injection reduces the drag and the transition is delayed/prevented, the magnetic field makes the dissipation very important because the kinetic energy of the electrically conductive fluid is absorbed by the Lorentz force, and the volume fraction and the density of nanoparticles increased the inertia of the fluid which decreased the speed gradient and damped the disturbances.

Purpose This paper aims to investigate the profile of the wind speed of a Cameroonian city for the very first time, as there is a growing trend for new wind energy installations in the West region of Cameroon. Two well-known artificial neural networks, namely, multi-layer perceptron (MLP) and nonlinear autoregressive network with exogenous inputs (NARX), were used to model the wind speed profile of the city of Bapouh in the West-region of Cameroon. Design/methodology/approach In this work, the profile of the wind speed of a Cameroonian city was investigated for the very first time since there is a growing trend for new wind energy installations in the West region of Cameroon. Two well-known artificial neural networks namely multi-layer perceptron (MLP) and nonlinear autoregressive network with exogenous inputs (NARX) were used to model the wind speed profile of the city of Bapouh in the West-region of Cameroon. The meteorological data were collected every 10 min, at a height of 50 m from the NASA website over a period of two months from December 1, 2016 to January 31, 2017. The performance of the model was evaluated using some well-known statistical tools, such as root mean square error (RMSE), mean absolute error (MAE) and mean absolute percentage error (MAPE). The input variables of the model were the mean wind speed, wind direction, maximum pressure, maximum temperature, time and relative humidity. The maximum wind speed was used as the output of the network. For optimal prediction, the influence of meteorological variables was investigated. The hyperbolic tangent sigmoid (Tansig) and linear (Purelin) were used as activation functions, and it was shown that the combination of wind direction, maximum pressure, maximum relative humidity and time as input variables is the best combination. Findings Maximum pressure, maximum relative humidity and time as input variables is the best combination. The correlation between MLP and NARX was computed. It was found that the MLP has the highest correlation when compared to NARX. Originality/value Two well-known artificial neural networks namely multi-layer perceptron (MLP) and nonlinear autoregressive network with exogenous inputs (NARX) were used to model the wind speed profile.

The aim of this paper is to analyze and compare efficiently of 10 (ten) numerical methods namely, the empirical method of Justus (EMJ), the empirical method of Lysen (EML), the method of moments (MoM), the graphical method (GM), the Mabchour’s method (MMab), the energy pattern factor method (EPFM), the maximum likelihood method (MLM), the modified maximum likelihood method (MMLM), the equivalent energy method (EEM), and the alternative maximum likelihood method (AMLM) in order to estimate Weibull parameters for wind energy potential. They were performed by using wind speed data collected in the meteorological station of Bafoussam city, in the west region of Cameroon, in the period from 2007 to 2013. The results of this study obtained from statistical analysis show that the MLM presents relatively more excellent ability throughout the simulation tests, followed by EEM, EPFM and EMJ respectively. They also demonstrated that EEM presented minimum error in estimating the monthly wind power density and that the wind potential of Bafoussam city can be interesting for some applications such as rural electrification and water pumping in agriculture.

In this paper, the performance of micro wind turbine (MWT) is evaluated by taking into account low average wind speed cities in the West Cameroon region such as Bandjoun and Bangangte. The k-ϵ turb...

This paper investigates the design, prototyping and experimental validation of a low-cost portable electrocardiograph made of standard electronic components. Indeed, the AD8232 and Arduino Nano board were used for the signal acquisition and digitization respectively. The electrocardiogram (ECG) signals obtained were visualized on a PC or an Android phone screen. The present portable electrocardiograph was used for the ECG signal acquisition of two anonymous patients (a healthy patient and pathological patient) in a Cameroonian hospital. The results were compared with the synthetic ECG and the one of the MIT database. They were in a good agreement and were also validated by a cardiologist as a promising solution for developing countries.

This paper aims to develop an automatic neonatal incubator equipped with phototherapy, biometric fingerprint reader, remote monitoring and heart rate control modules for developing countries due to the lack of neonatal incubators. The proposed device consists of an acquisition module that senses temperatures (of the enclosure and the baby) and humidity, a biometric fingerprint reader to identify the user, a remote monitoring module in charge of supervising the temperature and the heart rate of the baby, a video surveillance module which allows filming and transmitting the images to the web server in order to give parents and nurses the possibility of being able to visualize whatever their location the newborn baby, a phototherapy module used to treat newborn jaundice by lowering the bilirubin levels in the baby's blood, a digital control module from a pulse width modulation (PWM) signal generated by a microcontroller of Arduino Nano type for system operation monitoring, and a human machine interface module for setting parameters. The equations describing the energy balance and heat transfer for newborn baby (Ostrowski and Rojczyk, 2018) are taken into account for the implementation of power supply and the choice of the heating resistor. The desired temperature of 37 °C was obtained after only a few minutes inside the incubator.

Multipoint inoculator is a laboratory equipment that is used to inoculate with a very high precision a certain number of microorganisms in culture media, in order to determine the minimum inhibitory concentrations (MICs) of antibiotics that would inhibit microbial growth. MICs values are crucial in the control of microbial drug-susceptibility profile for effective infectious disease control and microbial resistance stewardship. The complexity of multipoint inoculator makes it very rare or almost non-existent in developing countries laboratories. In this paper, a robust, precise and, above all, innovative automatic multipoint inoculator is developed. Otherwise, we have implemented double-sided plates with surface-mounted components. These components of Nano-electronics have the advantage that the electrical circuits do no longer have to be drilled, the components can be placed on both sides of the board, and the parasitic electrical inductances are reduced. The equipment enclosure in plexiglas facilitates its sterilization. The device carries Petri dishes that contain culture media, opens them and performs inoculation. It then closes and stores the preparations that are ready for incubation at optimal growth conditions. The present device inoculates at a given concentration of an antibiotic 21 microorganisms simultaneously.

In this paper, we design and implement a low-cost automatic neonatal incubator equipped with a baby weight monitor in order to remedy the difficulties encountered with the maintenance of incubators in developing countries. Indeed, severe temperature fluctuations inside an incubator can lead to neonate heat loss, hypothermia and apnoea, which are closely related to temperature and air flow. The implemented device has been developed by interconnecting three modules. The first is the acquisition module that senses the temperature and humidity, the second is the control module in charge of monitoring and controlling the operation of the system and the third is the human machine interface module through which a user can set operating parameters of the system. The mathematical modeling of Proportional-Integral-Derivative (PID) controller and heat transfer allowed the minimization of heat loss across the wall of the enclosure. The incubator has been tested and the target temperature of 37 °C was reached after almost 15 min. Results from numerical simulation performed with the same condition of the test showed a good agreement between the simulation results and experimental results.

Apart from the techno-economic design of hybrid PV energy systems, their simulation and performance prediction help to validate the configurations in terms of reliability before implementation. However, they are not usually based on radiation data collected in short time interval due to their unavailability. In this work, after a techno-economic design of Photovoltaic/Diesel/Batteries, we propose to evaluate the energy performance through the simulation of energy flow by using hourly solar radiation data converted from monthly average values with the Duffie and Beckman algorithm. As a case study, the monthly average daily solar radiation data of Maroua were converted into one year hourly values. The hourly radiation data converted were used to simulate the energy flow of optimal configurations obtained by three different methods for three types of household electricity demands. From the hourly simulation, the technical performance was evaluated by observing the patterns of the battery state of charge, the excess and deficit energy, and by determining the loss of power supply probability and the renewable fraction. The results showed that the optimal configurations in terms of cost, reliability and sustainability consisting of PV of 200 W and batteries of 200 Ah were 2PV/2 batteries (0.8390 $/kWh), 4PV/2 batteries (0.6333 $/kWh) and 8PV/2 batteries (0.3665 $/kWh) respectively for the low, medium and high household energy consumers. It was also observed that, the proposed configurations will be profitable compared to grid cost if the distance from the grid line to the household is greater than: 650 m for the low and high consumers and 700 m for the medium consumer. The methodology proposed may be used to evaluate the performance and validate a hybrid system configuration especially for sites where the hourly radiation data are unavailable.

This paper deals with the numerical solution of inviscid compressible flows. The three-dimensional Euler equations describing the mentioned problem are presented and solved numerically with the finite volume method. The evaluation of the numerical flux at the interfaces is performed by using the Toro Vazquez-Harten Lax Leer (TV-HLL) scheme. An essential feature of the proposed scheme is to associate two systems of differential equations, called the advection system and the pressure system. It can be implemented with a very simple manner in the standard finite volume Euler and Navier–Stokes codes as extremely simple task. The scheme is applied to some test problems covering a wide spectrum of Mach numbers, including hypersonic, low speed flow and three-dimensional aerodynamics applications.

The TV-HLL solver for the numerical solution of fluid flow inside elastic vessels is constructed in this paper. The system of partial differential equations describing the fluid flow inside collapsible tubes is presented and solved numerically by using the finite volume method. The evaluation of the numerical flux at the interfaces is performed by using the TV-HLL scheme which is derived from the previous studies presented for solving the Euler equations (Tiam and Tchuen, 2014, 2015). Indeed, the present scheme is obtained by following the Toro-Vazquez splitting, and using the HLL algorithm with modified wave speeds for the pressure system. An essential feature of the TV-HLL scheme is to associate two systems of differential equations, called the advection system and the pressure system. The proposed scheme preserves the non-negativity of essentially nonnegative quantities (cross section). It has been applied to some one-dimensional numerical tests dealing with the fluid flow through the male urethra and the blood flow inside cerebral vessels.

The work presented in this paper aims to develop and implement a robust algorithm for generating synthetic phonocardiogram (PCG) signals based on characteristics obtained from real life signals. The purpose of this work is to identify a few set of parameters that can be linked to the physiological state of the heart. The mathematical model used in the synthesis of the signal was based on three coupled ordinary differential equations (ODE) proposed by Jabloun et al. (2013). The amplitude, S2S1 duration, and heart rate of the real life PCG signals were extracted and used in the synthesis of the signals. The real life PCG signals were obtained from the MITHSDB and AADHSDB databases from Massachusetts Institute of Technology and Aalborg University respectively. The signals were preprocessed using a second order Butterworth low pass filter of cutoff frequency of 500 Hz to obtain cleaner versions. The system of equations was numerically solved with the fourth-order Runge-Kutta method. These synthetic PCG signals were then compared with the real life PCG signals. The time domain correlations between the two sets of signals showed a good agreement between the two with values above 0.8 for all tested cases. The percentage differences in heart rate (beats per minutes), amplitude and S2S1 durations between the real life and synthesized PCG signals also showed a close match with percentage values as small as 1.61%, 2.27% and 4.51% for heart rate, amplitude and S2S1 duration respectively.

A robust algorithm is investigated for multidimensional inviscid compressible flows, based on rotated Riemann solver framework. Indeed, the proposed method combines the TV-HLL and Roe schemes. The upwind direction is imposed by the velocity-difference vector. Then, the TV-HLL solver is applied in the direction perpendicular to shocks in order to suppress carbuncle. In addition, the Roe solver is applied across shear layers to minimize the amount of dissipation. To assess the capabilities of the present method, numerous test problems (2D and 3D) are simulated.

The World health Organization estimates that about 8 million babies die prematurely worldwide. Most of these cases are found in low-income countries (LICs). The use of neonatal incubators has proven to be very useful in the reduction of infant mortality. However, access to this important medical device is not always easy in LICs. This article presents the implementation of a multi-function neonatal incubator with remote monitoring, fingerprint scanner, phototherapy, and heart rate monitoring. In this view, proportional integral (PI) control algorithm and an Android application were developed. Furthermore, an initial social impact of the implemented neonatal incubator usage was performed in some hospitals in Cameroon.

In this paper, synthetic electrocardiogram signals (SECG) of eight cardiac arrhythmias (sinus bradycardia, junctional bradycardia, tachycardia, flutter, atrial extrasystole, ventricular extrasystole, left branch block and right branch block) are obtained numerically by solving the McSharry mathematical model (2003) based on three coupled ordinary differential equations with the fourth-order Runge-Kutta method. They are compared with normal electrocardiogram signal. Indeed, visual analysis of a section of electrocardiogram (ECG) signals of these arrhythmias was used to suggest suitable values for the parameters in the McSharry mathematical model. Results from numerical simulation showed a good agreement between the simulation results and the real cardiac arrhythmias ECG signals.

This paper investigates a very simple method to numerically approximate the solution of the multi-dimensional Riemann problem for gas dynamics, using the literal extension of the Toro Vazquez-Harten Lax Leer TV-HLL scheme as its basis. Indeed, the present scheme is obtained by following the Toro–Vazquez splitting, and using the HLL algorithm with modified wave speeds for the pressure system. An essential feature of the TV-HLL scheme is its simplicity and its accuracy in computing multi-dimensional flows. The proposed scheme is carefully designed to simplify its eventual numerical implementation. It has been applied to numerical tests and its performances are demonstrated for some two-dimensional and three-dimensional test problems.

International audience; This paper deals with a simple approach of producing three gases that are oxygen, nitrogen and pressurized air by using a mobile three gas extractor. Indeed, the proposed medical device integrates the following modules driven by an Arduino Mega 2560 board: Module of filtration and production of air made of filters, compressor and a cooling coil; module of oxygen and nitrogen production based on pressure swing adsorption (PSA) method and using the zeolite molecular sieves that restrain nitrogen and produce oxygen. The device is equipped of pressure sensors to control the output pressure of the gases. This implemented equipment has been tested and we obtained promising results. Indeed, a percentage of oxygen of 82 % has been reached. We have produced pressurized air with a pressure of 2.5 bars.

This paper presents a new flux splitting scheme for the Euler equations. The proposed scheme termed TV-HLL is obtained by following the Toro-Vazquez splitting (Toro and Vázquez-Cendón, 2012) and using the HLL algorithm with modified wave speeds for the pressure system. Here, the intercell velocity for the advection system is taken as the arithmetic mean. The resulting scheme is more accurate when compared to the Toro-Vazquez schemes and also enjoys the property of recognition of contact discontinuities and shear waves. Accuracy, efficiency, and other essential features of the proposed scheme are evaluated by analyzing shock propagation behaviours for both the steady and unsteady compressible flows. The accuracy of the scheme is shown in 1D test cases designed by Toro.