Optimization of the Electronic Driver and Thermal Management of LEDs Lighting Powered by Solar PV

AbstractThe developments of efficient photovoltaic (PV) standalone systems requires advanced technology for PV cells and modules for high performance but also the application of components or loads of use with low energy consumption. In this context, the development of lighting systems using solar energy and electroluminescent components like high power white Light Emitting Diodes (LEDs) is proposed. The integration of the light fixture with the choice of best technologies for high efficiency LEDs and the design of an ultra-economic driver as the PWM driver permit us to obtain a high lighting efficiency. Our study has taken in consideration thermal aspect and the choice of adequate heat sinks for thermal management. This study, allowed us to consider both effects of thermal and electronic order and allowed us to the achievement of a high efficiency lighting powered by solar energy. With the implementation of the PWM electronic controls, we should reach an energy efficiency of the LEDs Driver from 85 to 90%

The influence of position in overlap joints of Mg and Al alloys on microstructure and hardness of laser welds

Structure and properties of laser beam welding zone of dissimilar materials, AZ31 magnesium alloy and A5754 Aluminum alloy, are investigated. The microstructure and quality of the Mg/Al weld were studied by metallography, microhardness and optical microscopy. Differences in physical and mechanical properties of both materials, magnesium and aluminum, affect weldability and resistance of this combination, and lead to the formation of intermetallic compounds in the welded metal

Estimability analysis and parameter identification for a batch emulsion copolymerization reactor in the presence of a chain transfer agent

In this paper we have developed an estimability analysis method to identify the subset of potentially estimable parameters from the proposed experimental data. The emulsion copolymerization model involves 59 unknown parameters. The complete set of parameters cannot be estimated from the experimental measurements available. Thanks to the method developed, 21 parameters were selected and identified. The non estimable parameters were set to nominal values taken from literature. The mathematical model was validated under both batch and fed batch conditions

Analysis of optimal operation of a fed-batch emulsion copolymerization reactor used for production of particles with core-shell morphology

In this paper dynamic optimization of a lab-scale semi-batch emulsion copolymerization reactor for styrene and butyl acrylate in the presence of a chain transfer agent (CTA) is studied. The mathematical model of the process, previously developed and experimentally validated, is used to predict the glass transition temperature of produced polymer, the number and weight average molecular weights, the monomers global conversion, the particle size distribution, and the amount of residual monomers. The model is implemented within gPROMS environment for modeling and optimization. It is desired to compute feed rate profiles of pre-emulsioned monomers, inhibitor and CTA that will allow the production of polymer particles with prescribed core-shell morphology with high productivity. The results obtained for different operating conditions and various additional product specifications are presented. The resulting feeding profiles are analyzed from the perspective of the nature of emulsion polymerization process and some interesting conclusions are drawn

Emulsion copolymerization of styrene and butyl acrylate in the presence of a chain transfer agent. Part 2: parameters estimability and confidence regions

Accurate estimation of the model parameters is required to obtain reliable predictions of the products end-use properties. However, due to the mathematical model structure and/or to a possible lack of measurements, the estimation of some parameters may be impossible. This paper will focus on the case where the main limitations to the parameters estimability are their weak effect on the measured outputs or the correlation between the effects of two or more parameters. The objective of the method developed in this paper is to determine the subset of the most influencing parameters that can be estimated from the available experimental data, when the complete set of model parameters cannot be estimated. This approach has been applied to the mathematical model of the emulsion copolymerization of styrene and butyl acrylate, in the presence of n-dodecyl mercaptan as a chain transfer agent. In addition, a new approach is used to better assess the true confidence regions and evaluate the accuracy of the parameters estimates in more reliable way

Dynamic simulation of hybrid differential algebraic systems using GPROMS: case study in emulsion polymerization

This paper is deals with dynamic simulation of a semi-batch polymerization reactor for emulsion copolymerization of styrene and butyl acrylate in the presence of n-dodecyl mercaptan as chain transfer agent (CTA). Mathematical model of the polymerization reaction involved is used to predict the glass transition temperature of produced polymer, global monomer conversion, the number and weight average molecular weights, the particle size distribution and the amount of residual monomers. This model, a set of hybrid differential algebraic equations (DAEs), is implemented into gPROMS environment for modeling, simulation, and optimization

Emulsion copolymerization of styrene and butyl acrylate in the presence of a chain transfer agent. Part 1: modelling and experimentation of batch and fedbatch processes

This paper deals with the development of a mathematical model for emulsion copolymerization of styrene and butyl acrylate carried out in the presence of n-dodecyl mercaptan as chain transfer agent (CTA). The model consisted of a system of differential algebraic equations in which the population balances are based on a new approach that reduces significantly the number of equations involved and the corresponding computational time. Most of the unknown kinetic and thermodynamic parameters of the model were estimated from experimental measurements using a stochastic optimization method based on a genetic algorithm. The results showed a fairly good agreement between model predictions and experiments. The model was then successfully validated through additional experiments carried out in batch and fedbatch reactors and clearly showed that the model was able to predict the time-evolution of overall conversion, amounts of each residual monomer, number and weight average molecular weights of the resulting copolymers and average diameters of the corresponding latex particles for different operating conditions, mainly CTA concentration and reaction temperature. The model was finally used to investigate and confirm the effects of CTA concentration, previously observed by several authors, on the kinetics of this polymerization process and on the main properties of the resulting macromolecules and latex particles

Multiobjective dynamic optimization of a fed-batch copolymerization reactor

Multiobjective optimization problems are encountered in most real-world applications and more recently in chemical processes ([1], [2], [3], [4]). Since such problems involve several objective functions with conflicting nature, the final optimum is not unique but a set of non dominated solutions (the Pareto front) which show a trade-off among the whole objectives. A decision support approach is then used to rank the Pareto solutions according to the decision maker’s preferences

A genetic algorithm for shortest path with real constraints in computer networks

The shortest path problem has many different versions. In this manuscript, we proposed a muti-constrained optimization method to find the shortest path in a computer network. In general, a genetic algorithm is one of the common heuristic algorithms. In this paper, we employed the genetic algorithm to find the solution of the shortest path multi-constrained problem. The proposed algorithm finds the best route for network packets with minimum total cost, delay, and hop count constrained with limited bandwidth. The new algorithm was implemented on four different capacity networks with random network parameters, the results showed that the shortest path under constraints can be found in a reasonable time. The experimental results showed that the algorithm always found the shortest path with minimal constraints

Prediction of thermomechanical behavior of acrylonitrile butadiene styrene using a newly developed nonlinear damage-reliability model

The aim of this work was to evaluate the influence of temperature on the mechanical behavior of an amorphous polymer, namely acrylonitrile butadiene styrene (ABS), based on a series of uniaxial tensile tests on smooth specimens at different temperatures. The results demonstrate that the behavior of the polymers is strongly dependent on the temperature. Its influence on the physical characteristics during the study of polymer behaviors cannot be denied, particularly when the processes of shaping are investigated, which require significant contributions of heat and mechanical effort. For this reason, this study consists of predicting the evolution of ABS damage in two main zones. The first is the industrial zone, in which the configuration of macromolecular chains is largely immobile, and the temperature is below the glass temperature (Tg = 110°C). In this zone, a damage model based on the obtained experimental results allowed us to determine three stages of damage evolution, and then to specify the critical fraction of life, at which the material becomes unstable and defective, for the purpose of predictive maintenance. The second zone is that of thermoforming, in which the temperature is above the glass temperature, Tg. In this zone, the macromolecular chains tend to move more freely as the temperature increases. The same damage model was adopted to follow the flow process according to the fraction of life that represents the critical material parameter. This study also includes a comparison between the static (experimental) damage models and unified theory (theoretical) damage models