CONTROL AND MANAGEMENT OF A SOLAR-WIND HYBRID SYSTEM FOR POWER QUALITY IMPROVEMENT

The main aim of this paper is to present a modified Maximum Power Point Tracking (MPPT) control strategy of a solar-wind hybrid power system, which allows producing a maximum of energy while enhancing the produced power quality by reducing its fluctuation rate. Indeed, the Photovoltaic System (PVS) is based on a PV field of panels connected to the grid through a DC-DC and DCAC PWM converters and the Wind Energy Conversion System (WECS) is based on a stator field oriented Doubly Fed Induction Generator (DFIG) which its rotor is connected to the network via a back to back AC-DC-AC PWM converter. The proposed control strategy ensures a conventional Maximum Power Point Tracking (MPPT) for the WECS. Furthermore, it guarantees a smooth power injected in the grid by applying a modified MPPT technique applied to the PV system. This strategy uses a part of the PVS available power to compensate the WECS power fluctuations due to wind gusts and generates simultaneously the maximum of smoothed power from the residual part. The simulations results obtained in the case of the proposed control strategy have been compared to those of a conventional MPPT technique and of a Guaranteed Minimum Available Power (GMAP) control strategy. It is obvious that the proposed modified MPPT keeps a good compromise between the quantity and the quality of the total hybrid system produced power

Process intensification of liquid-liquid non-isothermal processes by using chemical reactor-heat exchanger (L/L HEX)

The present document reports the work accomplished, from February 1998 to the end of September 2000, by "Équipe Thermofluides & Écoulement Complexes" of ISITEM (university of Nantes), in the framework of the Joule Project No. JOE3-CT97-0050. This partner will be referred to as ETEC, hereafter. The task assigned to ETEC was mainly focused on the hydrodynamic characterization of Liquid/Liquid (L/L) flows in chemical reactor-heat exchangers. Although the device is supposed to be fed with reacting products, flow characterization experiments are to be carried out with non reacting fluids, for safety and practical reasons. The studies to be performed by ETEC were of experimental type. As a consequence, the preliminary work consisted of purchase, design and construction of experimental facilities for the purpose of the project. These will be described in the chapters one, two and three where we address the generalities, single and two phase studies. As have been explained in the periodic reports, characterization of a turbulent two phase L/L flow in a given geometry requires detailed information of the single phase turbulent flow occurring in the same geometry. Therefore, it has been agreed at the kick off meeting (Brussels, on 4th March 1998) that the first step of ETEC’s experimental investigations focuses on a single phase flow characterization in turbulent regime. This work have been accomplished and has given satisfying results that will be presented in chapter. The second step of the work was then focused on the two phase L/L flow. For this purpose, two experimental techniques have been developed to obtain accurate measurements of droplets characteristics. The techniques are based on a micro encapsulation operation. It required several calibration experiments that have been performed

Effect of Treatment Methods on Used Lubricating Oil for Recycling Purposes

The need to treat used lubricating oil for possible reuse has arisen due to concern for the environment, scarcity, price stability, and increasing dependence on this product for many industrial applications. Various methods, such as distillation/clay, acid/clay, acid, and activated charcoal/clay treatment methods, were employed in this study for the treatment of used Mobil and Total lubricating oil samples with the aim of improving their qualities for reuse. The characteristics of the fresh, used, and treated oil are tested for water content, specific gravity, kinematic viscosity, viscosity index, flash point, pour point, sulphur content, and concentrations of heavy metals (aluminum, iron, and lead). The results obtained showed that the usage of the lubricant oil affects the qualities of oil, for instance the sulphur of both brands of the oil samples was below the detectable limit, while the sulphur contents of the used oil are 0.80 and 0.69% for the used Mobil and Total oil samples, respectively. The results also revealed that treatments employed in this work were able to improve the characteristics of the used oil samples after treatment. The analyses of the results showed that the acid/clay method was the most effective method of treatment that brings the characteristics of the treated oil close to the fresh oil sample, while the distillation/clay and activated/charcoal methods were the best in terms of recovery of the oil after treatment. These two methods also recovered about 80% of the used lube oil samples compared to acid and acid/clay treatment methods, where the oil recovered was about 50% of the charge used oil sample

Synthesis of zirconia-based solid acid nanoparticles for fuel cell application

Zirconia nanoparticles were prepared by the precipitation and ageing methods. The precipitation method was performed by adding ammonium solution to the aqueous solution of zirconium chloride at room temperature. The ageing method was performed by leaving the precipitate formed in the mother liquor in the glass beaker for 48 hours at ambient temperatures. The nanoparticles from both methods were further sulphated and phosphated to increase their acid sites. The materials prepared were characterised by X-ray diffraction (XRD), thermo-gravimetric analysis (TGA), Brunauer-EmmettTeller (BET), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) methods. The XRD results showed that the nanoparticles prepared by the precipitation method contained mixed phases of tetragonal and monoclinic phases, whereas the nanoparticles prepared by ageing method had only tetragonal phase. The TEM results showed that phosphated and sulphated zirconia nanoparticles obtained from the ageing method had a smaller particle size (10–12 nm) than the nanoparticles of approximately 25–30 nm prepared by precipitation only. The BET results showed that the ZrO2 nanoparticles surface area increased from 32 to 72 m2/g when aged

Piezoelectric vibration damping using resonant shunt circuits: an exact solution

peer reviewe

The minimum norm multi-input multi-output receptance method for partial pole placement

A closed-form analytical solution is developed for the first time that fully addresses the problem of choosing feedback gains that minimize the control effort required for partial pole placement in multi-input, multi-output systems. The norm of the feedback gain matrix is shown to take the form of an inverse Rayleigh quotient, such that the optimal closed-loop system eigenvectors are given as a function of the dominant (highest)eigenvectors of the matrix in the quotient. The feedback gains that deliver the required pole placement with minimum effort may then be determined using standard procedures. The original formulation by the receptance method proposed an arbitrary choice of the closed loop eigenvectors that assigned the poles exactly but was generally wasteful of control effort that might otherwise be conserved or put to good use in satisfying additional control objectives. The analytical solution is validated against a set of numerical examples

Vaccination with UV-inactivated nodavirus partly protects European sea bass against infection, while inducing few changes in immunity

Developing viral vaccines through the ultraviolet (UV) inactivation of virus is promising technique since it is straightforward and economically affordable, while the resulting viruses are capable of eliciting an adequate antiviral immune response. Nodavirus (NNV) is a devastating virus that mainly affects European sea bass juveniles and larvae, causing serious economic losses in Mediterranean aquaculture. In this work, a potential vaccine consisting on UV-inactivated NNV (iNNV) was generated and administered to healthy juveniles of European sea bass to elucidate whether it triggers the immune response and improves their survival upon challenge. First, iNNV failed to replicate in cell cultures and its intraperitoneal administration to sea bass juveniles also failed to produce fish mortality and induction of the type I interferon (IFN) pathway, indicating that the NNV was efficiently inactivated. By contrast, iNNV administration induced significant serum non-specific antimicrobial activity as well as a specific antiviral activity and immunoglobulin M (IgM) titres against NNV. Interestingly, few changes were observed at transcriptional level in genes related to either innate or adaptive immunity, suggesting that iNNV could be modulating the immune response at protein or functional level. In addition, the iNNV vaccinated group showed improved survival, reaching a relative survival percentage of 57.9%. Moreover, challenged fish that had been vaccinated presented increased serum antibacterial, antiviral and IgM titres, as well as the higher transcription of mhc1a, ifn, isg15 and cd8a genes in brain, while in the head-kidney the transcription of mhc1a, mhc2b and cd8a was down regulated and mx, isg15 and tcrb was up-regulated. Although the UV-inactivated vaccine against NNV showed promising results, more effort should be addressed to improving this prophylactic method by increasing our understanding of its action mechanisms, thus enabling the mortality rate of NNV to be further reduced.Postprint3,26

XPS study of the band alignment at ITO/oxide (n-type MoO3 or p-type NiO) interface

While they have different electronic properties n-type MoO3 and p-type NiO are very efficient as buffer layers between the ITO anode and the organic electron donor in organic photovoltaic cells. While it is admitted that MoO3 is n-type, its band structure is still under study. Here, the band alignment at the interface of an ITO/MoO3 heterojunction is studied by X-ray photoelectron spectroscopy (XPS). The same study is realized on the structure ITO/NiO, NiO being a p-type semiconductor. The measurements have been performed on samples obtained under the same experimental conditions as those used to achieve organic photovoltaic cells. The MoO3 (NiO) upper layer was 3 nm thick. The semidirect XPS technique used to measure the band offsets allows us to estimate the band discontinuities at the interface ITO/MoO3: ΔEv = 0.50 eV and ΔEc = 0.90 eV, while at the interface ITO/NiO we have ΔEv = −2.10 eV and ΔEc = −1.90 eV. Therefore, n-type MoO3 and p-type NiO, which are both very efficient anode buffer layers (ABLs), exhibit different band structure at the contact with ITO. However, the measurement, by means of a Kelvin probe, of the work functions of the structures ITO/NiO and ITO/MoO3, shows that they are close and significantly higher than that of ITO alone