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The interest for a researcher to follow a participatory research approach compared to a conventional approach is multiple. The aim of this project is to make scientific research accessible to everyone, especially high school students. Our approach is a new concept of learning by doing for high school students that adopt the posture of a researcher to solve a problem presented to them. Students propose working hypotheses, imagine their protocol, experiment, discuss and communicate their results. High school students are supervised by the PhD students and the results from these studies are used for their research work. Currently several French and international Universities have approached us to implement this participatory research.

This paper investigates the Weibull distribution analysis for an accuracy global solar irradiance assessment considering period measurements based on several and grouping years. The problem study in this paper is to find a global solar irradiance model in order to provide accurate estimation of PV energy output allowing better sizing of PV installation. The aim is to select the best Weibull fit procedure for obtaining reliable global solar irradiance from sun that incident in a place during time periods to estimate its yearly energy generation from PV plant. Comparisons are carried out between Graphic, Moments and Maximum Likelihood methods with two different databases (real data on-site measurements and SODA website database). These comparisons are made on global solar irradiance frequency distributions and annual solar irradiance assessment for different French locations. The originality of the paper is that the obtained results prove that the Maximum Likelihood method fits better with the global solar irradiance distribution while the Moment method provides an annual solar irradiance prediction. Thereby, we exploit the obtained results from the Moment method to achieve a more accurate solar energy forecasting model. This resulting model can be implemented for providing one solar energy estimation tool for PV plant sites.

Building-based active envelopes play an important role to reduce active heating supplies. Several techniques are developed to enhance the energy performances of active building envelopes; meanwhile, numerous numerical and mathematical models are also developed to conduct the performance analysis of these techniques. In this paper, we propose a state-space model for solar active wall-based Phase Change Materials (PCM). The advantage of this method remains in its simplicity to provide details of internal nodes and input/output parameters. The low-cost calculation is a supplementary advantage versus a heavy numerical method. The proposed numerical model is applied for a multi-layer wall with PCM Wallboards (PCMW) embedded between indoor and outdoor environments. The results show the ability of the state-space model to estimate the thermal behavior of the system, as well as the thermal characteristics of embedding PCM in the internal face of the wall. It significantly contributes to stabilize the indoor temperature and to ensure the thermal comfort.

The goal of the work carried out is firstly to achieve a model of parameters influencing the performance of photovoltaic (PV) energy output under real working conditions and secondly implementing the model into a single Field Programmable Gate Array (FPGA) that should be applied to energy management for future smart building design. Only the former aspect is discussed in this paper to guide the undergoing research laboratory theme of the latter as the GREEN platform is equipped with several renewable energy technologies for modeling, managing and optimization of energy consumption. It's well known that PV nominal specifications such as power output or energy yield of recent modules are evaluated by manufacturers under Standard Test Conditions (STC) that are generally not representative of real working conditions of solar modules. In this study, we showed high correlation between the operating cell temperature (Tc) and the measured back surface temperature (Tback) of polycrystalline PV modules in real experimental conditions. Methods used in previous study referred mainly to ambient temperature. An accurate relationship is derived for power output between solar irradiance φ (W/m2) and the back surface temperature and the calculated power output is compared to measured power output data with a high correlation coefficient. This power output is introduced in the Weibull probability density function to model the energy yield which is finally compared to real conditions recorded data. Good concordance is shown between the proposed model and measured data of energy yield for the middle year (2013) and last year (2016) of the seven years range experimental data of a semi continental zone. The model is ready to be implemented on FPGA chip to be compared to real working high temperature environment conditions.

The high irradiance in tropical area is certainly favorable to photovoltaic (PV) power output, since the efficiency depends on the solar radiation intensity. However the increase of cells temperature causes conversely a fall of the yield of the modules. This decrease in the performance of PV modules due to temperature effect also causes proportional voltage decrease. This drop in performance is at the expense of destabilisation of the electrical network and if the electrical power output of modules is planned for a total grid injection. A time series may be useful in forecasting another time series and this statistical hypothesis test is called the Granger causality test. In this paper, we show that the Granger causality can be applied to PV parameters time series and an error correction model is used to determine a long term relationship of power output for PV systems.

Optical information security is one of the most important research directions in information science and technology, especially in the copyright protection, confidential information transmission/storage and military remote sensing. Since double random phase encoding technology (DRPE) was proposed, optical image encryption technology has become the main topic of optical information security and it has been developed and studied deeply. Much significant research and investigation on optical image encryption have been presented based on DRPE or further optical operation, such as digital holography, and Fresnel transform, gyrator transform. In this paper, the optical encryption system for gray image and color image is reviewed.

International audience; Photovoltaic (PV) modules are given a power rating at standard test conditions (STC) of 1000 W/m2 , AM1.5, and a module temperature of 25∘C. However, these conditions do not represent what is typically experienced under outdoor operation. PV technologies have different seasonal output behavior under real operating conditions due to variations of irradiance and different temperature coefficients of voltage and current that do influence on energy output. Solar photovoltaic resources can be modeled probabilistically, and a probability density function of the solar generation can be estimated. In this paper, we applied the Weibull analysis for energy output estimation to a small-scale photovoltaic power generator in real conditions and undergoing environmental stresses for a specific location. We studied two types of modules: crystalline silicon (c–Si) and amorphous silicon (a–Si) in real outdoor conditions. We measured and calculated monthly and annual power output and compared each system performance.

Currently, with the explosive growth of the Internet of Things (IoT) technologies and systems, an increasing number of practical applications can be found in many fields including industry, asset tracking, agriculture, smart metering, smart city and building. IoT sensors based on Low-Power Wide-Area (LPWA) Network technologies appears suitable for the deployment of instruments and sensors on a traditional telecom tower to develop additional services for tower Company allowing a better monitoring of its facilities, energy consumption and various equipment supervision. As many telecom sites are close to cities, they can also contribute to develop services for the future smart city and building needs. However, this feasibility must be performed in a real use of Telecom Tower conditions, such as frequency interference. In this paper, we propose a method to equip a telecom tower considering the Long Range Wide Area Network (LoRaWAN) protocol in order to gather data from IoT sensors networks that are deployed in the surrounding buildings. We show that the use of the top of telecom tower allows a large private LoRaWAN network covering up to 32 km with only one gateway. Data from different sensors are retrieved directly on local computers and on Cloud applications for further processing. Dashboards are then realized from IoT platforms for monitoring and energy management of telecom towers which can be extended to the buildings smart supervision and control.

In this work, a multiband frequency reconfigurable Dielectric Resonator Antenna for different wireless protocols has been discussed. The overall design consists of Dielectric Resonator (DR) placed on Fr4 substrate. The resonator is excited by CPW (coplanar waveguide). The feedline, ground and radiator are positioned on the same surface. The overall design is low profile because of the reduced height of the DR. The DR has relative permittivity $\left(\varepsilon_{\mathrm{r}}\right)$ of 15. The dual band design is reconfigured to other four bands with the help of two switching configurations. The resonant frequencies are reconfigured between 1.2 GHz to 6.5 GHz. The substrate FR4 has a thickness of 1.6mm and 0.002 tangent loss. The ground plane has the dimensions of 50×45 mm2. The DR has an height of 2mm. Two ideal switches SI and S2 are placed on the two sides of the feedline. The combination of these two ideal RF PIN diodes is used to obtain three switching arrangements. A fourth possible arrangement is excluded as it disconnects the DRA from the feedline. The switching arrangements are ON-ON, ON-OFF and OFF-ON. In ON-ON state, the two achieved resonance frequencies are 4.27 GHz (WBAN) and 5.64 GHz (WLAN). In ON-OFF state the obtained resonance frequencies are 2.1 GHz (LTE) and 5.47 GHz (WLAN). For ON-OFF state, the two resonance frequencies are 2.16 GHz (LTE) and 5.73 GHz (WLAN). The simulated values for all the switching configuration confirm the potential of the prototype for use in the targeted wireless protocols.

Micro-wind turbine are now specially designed for rural or urban environment and one of the main advantages of such turbine is that it can be propelled by a wind speed as low as 3 m/s. However, due to terrain roughness in urban environments wind flow is reduced compared to open spaces reducing power output and increasing payback time on capital investment. Well mounting turbines in urban areas may provide the perfect opportunity for onsite generation from wind power. In this paper, we investigate the performance of a micro-wind turbine in a complex urban area and show that due to long time period and very subtile onsite measurements the ideal position for the wind turbine can be determined. Well measured data, wind speed, power output at this particular location are approximated by the Weibull function. The considered model is tested and validated at an urban landscape location in Metz City, France, where an anemometry is positioned at adjacent to the turbine and the instrumentation is positioned specific to its surrounding location and, record wind turbine data thanks to real time wireless communications. Technical data including wind speed and output power were analyzed and reported allowing to provide an reliable estimation of the wind energy potential in an urban location.

In this work a wideband frequency reconfigurable Dielectric Resonator antenna (DRA) for WIMAXlWLAN and WBAN applications has been communicated. The reconfigurable antenna comprises of Coplanar Waveguide where ground plane and feedline are on the same surface. The DRA has been reduced to inverted U-shape for the sake of size miniaturization. The proposed design has the potential to reconfigure the frequencies at four different wide bands. The frequencies are tuned between 3.23 GHz to 6.32 GHz. The DRA has a dielectric constant (er) of 10 and is positioned on the ground plane with substrate of FR4 material, which has a dielectric constant of 4.3 and 1.6mm thickness. The overall dimensions of the design are 56χ55 mm2. Two ideal switches are positioned on the extended feedline to DR. Because of these two switches, three switching operations are performed, i.e, ON-ON, ON-OFF, OFF-ON. Because of these three switching operations, four wide bands are achieved. When switches are in ON-ON state, the impedance bandwidth is 48.88%. When switches are in ON-OFF state, two wide bands are achieved with 6% and 30.44 % impedance bandwidth respectively. For the third arrangement, when switches are in OFF-ON state, the impedance bandwidth is 28.88%. The proposed design is low profile with 1.635 mm height of the DR. Simulated results of the proposed design strongly support the design for the mentioned wireless applications.

In this paper, we investigate the performance of a micro-wind turbine in a complex through the power output prediction for decision making. The power output at one particular location can be approximated by the Weibull function. The considered model is tested and validated at an urban landscape location in Metz City, France, where anemometry is positioned at adjacent to the turbine and the instrumentation is specific to its surrounding location including record wind turbine data thanks to real time wireless communications. Technical data including wind speed and output power were analyzed and reported allowing to provide a reliable estimation of the wind energy potential in an urban location upon five years experimental data.

A novel asymmetric cryptosystem for optical image is proposed using fingerprint based on iterative fractional Fourier transform. To enhance the security, a hyperchaotic phase generated by a 4D Lorenz system is considered as the public key in the proposed encryption system, while the private key is emerged by the retrieved phase and fingerprint. In the encryption process, the secret information is hid into the hyperchaotic phase. Subsequently, the private key can be obtained by a reversible operation. To decrypt the original image, the ciphertext and private key are imported into the input plane of fractional Fourier system. This system is also applicable for information authentication because the fingerprint is used both in encryption and decryption approach. Some numerical simulations have been done to test the validity and capability of the encryption system.

Air conditioning systems are seen as a crucial part of any structure because they are directly related to the comfort of the occupants. Finding a conditioning system that exhibits not only a high level of comfort, but also a decrease in energy consumption and cost of the system is now very much preferable, especially with the ever-increasing cost of energy. Mixed convection for different boundary conditions and different configuration is carried out. In addition, a flow is injected through a window and extracted through an opposite window. In this work we examine the influence of the value of the Rayleigh number on the flow structure. The numerical analysis was carried out using the ‘Fluent’ software. To deal with turbulence the RNG k-ε model was adopted in this study. The study of ventilation efficiency has shown that the intensity of the recirculation flow increases near the adiabatic wall with the increase of Rayleigh number.

This work focuses on a horizontally ventilated cavity filled with air, heated on one side wall and cooled on the floor surface. Therefore, this study has been carried out for a convective loop induced for a fixed Rayleigh number Ra = 106 and horizontal ventilation (moderate Reynolds number Re = 100) where the injection is either in cooperating or opposing to the convective loop. The study undertaken concerns different opening position in order to analyze the energy efficiency of such ventilation and the corresponding indoor air quality. The results obtained indicate that the natural convection and the forced flow (ventilation) play an important role in the flow structure and the mixing ability, the heat exchange (cooling need) and the temperature comfort. The optimum ventilating position is a compromise in order to minimize the cooling demand, keep the mixing ability and reduce the temperature heterogeneity.

To develop efficient Li-ion powered systems, Cell testing and charactering are required to evaluate cell performance. However, testbenches are really expensive and test procedures provided are not the ones expected. In this article, we propose a testbench design based on Instrumentation software and hardware co-design. An efficient charging and discharging hardware has been proposed and developed by using a remotable laboratory supply as main virtual component. Software mechanisms are explained where the test procedures are detailed. in a second part. Acquisition constraints for measuring equipment are also specified in order to obtain relevant and valid data.

The cell management is as much important as the cell charge method. In order to manage effectively cell, a good knowledge of cell behaviors is required. Behaviors - electrical and thermal - are captured by the cell model. Cell modeling is very common in literature, but parameters extraction is not precisely explained. This paper will deal at first with an electro-thermal model based on extended Kalman filtering (EKF), which can allow to extract parameters, and in a second time with a fast and accurate measurement procedure.

Power production based solar cells are sensitive to temperature. In real conditions, the effective Photovoltaic (PV) module operating temperature is affected by randomly varying of solar radiation, ambient temperature and wind speed. Thus, the energy balance of photovoltaic (PV) cells and the associated power production is mainly modeled based on climate variables. This paper investigates the experimental influence and relationship of the temperature and solar radiation changing effects on the system performance in terms of power production of PV cells. An experimental approach leading to an expression models the energy transfer processes and electrical energy production for one specific site is studied. The proposed gait is reproducible and suitable on different site. Our study is based on experimental results set up of 6 PV (1 kW) multicrystallin silicon panels under existing conditions and not indoor conditions. 2 with a temperature of 25˚C. However, in the real world, these conditions are constantly changing. Therefore, the panel output is different from the laboratory conditions. Thereby, most previous works in the literature mainly have studied the thermal model in order to modeling and characterizing the behaviors of the various thermal effects and exchanges (through radiation, convection, conduction) of the PV cells (usually amorphous silicon area) in order to knowing the energy production according to climate conditions. However, few of them model the prediction of energy production from trend of thermal behaviors in function of the prediction prevailing weather conditions and surrounding environment. Therefore for determination of the expected energy production from exact temperature of PV cells, It is necessary to provide a suitable real model of the PV cells behaviors in order to predict electrical energy that can be supplied. To develop efficient renewable and sustainable energy for power production systems, the strong understanding of electro-thermal behaviors of the PV is required. Indeed, a behavior model compared to experimental measurement results contributes to predict the current and power production variations which must be taking into account in the sizing installation and manufacturing of solar energy production system, and energy distribution network based on PV. This paper investigates the experimental relationship of the temperature conditions (and thus solar radiation changing effects) on the system performance in terms of power production of PV cells in order to predict the potential of electric production for a given specific PV cell technology and according to the site of solar exposure .In this paper, we focus this work mainly on experimental observations of the temperature influence (5, 6) on the global efficiency (7), and thus on electrical power production. Thus, an experimental approach leading to an expression models the energy transfer processes and electrical energy production for one specific site and varying the time is studied. The rest of this paper is organized as follows. Section II presents the temperature effect on electrical current and power production. Section III describes the experimental PV modeling based on parameter value extraction depending temperature influence of real PV silicon cells varying in the time for one specific site. The details of the procedure measurement for determining the PV characteristics through experimental results are given in this section. In this Section, experimental measurements under real conditions are performed to quantify the relationship influence of the temperature in term power production. Finally, a conclusion is given in section IV.

Like all semiconductor devices, solar cells are sensitive to temperature. In actual installations the cell temperature rises leading to a total efficiency reduction, which cannot be overlooked. This paper investigates the influence of the temperature and solar radiation changing effects on the system performance. Our study is based on experimental results set up of 6 PV multicrystallin silicon panels under existing conditions and not indoor conditions.

Li-ion rechargeable batteries present an useful energy, low battery effect, and slow Self-discharge loss of charge when not in use. In this paper, we describe a VHDL-AMS model describing coupled electrical and thermal behaviors of a Li-Ion cell. This model relies on the experimental extraction of real characteristic parameters by using an efficient and low-cost test bench. Therefore, it allows to predict the realistic voltage variations by taking into account the state of charge and heating of the Li-ion cell, in order to design a battery system according the required capacity and electric power for the current electrical applications.

We were mainly concerned here with multiple exposure gratings that allow interactions and coupling between gratings. We started the study of interactions and coupling with five gratings recorded in dichromated gelatin (DCG). Having determined experimentally the characteristic parameters of these five gratings, we used a method developed by Oxford University to synthesize the modulation profile. Entering these parameters of each grating into our computing programs (based on the alternative theory of diffraction in modulated media) and by varying the amplitude modulation, the latter was deduced by adjusting the numerical curve to the experimental one. We then extended the study to nine multiplexed gratings. This study allowed us to know the range of the amplitude modulation such that a certain number of angular multiplexing can be done in DCG. Several undesirable effects which we had experimentally observed appeared then during the reconstruction of any one of the multiplexed images, such as cross-talk effect. We noted the good concordance between experimental and theoretical results. We finally illustrated cross-talk effect in a diffractive memory where, if the amplitude modulation was first calculated, the number of multiplexing for an angular range could then be determined and the angular separation achieved to avoid cross-talk.

An organic Rankine cycle (ORC) is simply a steam cycle in which the traditional steam is replaced by refrigerants or hydrocarbons. ORCs utilize clean energy resources: geothermal fluids, solar irradiation, ocean thermal gradient, heat from biomass combustion and waste heat from industrial thermal processes. The interest is growing over this technology. Large systems (> 400 kW) are commercially available while small scale systems are still under development. This technology is a new opportunity for industries and alternative solution for clean power generation. This paper recalls ORC principles, outlines challenges to be overcome (working fluids, small expanders design, performance map, heat exchangers integration, and project guidelines) and gives few data on the ORC market.

Two thousand images of resolution 512×512 pixels as a regular matrix pattern of 10×10 elements are stored, where each element is angularly multiplexed 20 times in a 25 μm thickness of dichromated gelatin emulsion without cross-talk effect. The surface area of the matrix is 1 cm2. We show good concordance of the angular selectivity between the experimental result and theory. The diffraction efficiency of each 20 multiplexed images is measured and has nearly the same value. Examples of reconstructed images for multiple applications are given, for example, storage of 160,000 images on a 3′1/2 floppy disc format, which is about 100 min of black and white film. Application can be made to automobile cartography and storage of X-ray images as well as weather forecast images. Colored diffractive images are also possible and are illustrated.

We describe the storage of 2000 images of resolution 512 3512 pixels as a regular matrix pattern of 10310 elements, where each element is angularly multiplexed 20 times in a 25-?m thickness of dichromated gelatin emulsion without crosstalk effect. The surface area of the matrix is 1 cm2. We show good concordance of the angular selectivity between the experimental result and theory. The diffraction efficiency of each of the 20 multiplexed images has been measured and has nearly the same value. Examples of reconstructed images for multiple applications are given, for example, storage of 160,000 images on a 3/2-in. floppy-disk format, that is, about 100 minutes of black-and-white films. Applications to automobile cartography and for storing x-ray and weather forecast images are possible. Colored diffractive images are also possible and are illustrated.