Petri Nets Models for Analysis and Control of Public Bicycle-Sharing Systems

International audienc

CFD based analysis of flow-driven vertical axis hydrokinetic turbines: blade hydrofoil and interactions effects

In last years, interest in hydrokinetic energy conversion (HEC) technology has grown. However, HEC technology requires advancements to become successful for practical in-situ conditions. In this study we investigated the Darrieus type vertical axis hydrokinetic turbines (HKT). Simulations are carried out using commercial CFD package to study the hydrodynamic behavior of a three bladed turbine. Two HKT with same solidity equal to 0.17 were considered, a 1st with symmetric-NACA0018 blade hydrofoils and a 2nd with cambered-NACA4415 blades. Our simulations show a shift in instantaneous torque coefficients for two different tip-speed ratio (TSR) values. For TSR = 1, the 2nd HKT has a delay compared to the 1st HKT, while for TSR = 2 it has a lead. NACA0018 provides highest troque coefficients. For a hydrofarm use, it is important to consider the interactions between hydrokinetic turbines. We investigated the effect of streamwise distance on performance of a Darrieus turbine. A distance of about 11 times the diameter of HKT along the streamwise direction seems essential

Modeling and control of series resonant converter for high voltage applications

International audienceMost industrial processes that use electricity as a source of voltage or current, require power circuit for the control of its physical quantities. Power converters are a multi-site privileged in the control of high power systems.In this article we show that the series resonant DC/DC converter, which is a hybrid system. The SRC achieves an output DC voltage equal to n times the input voltage of the converter, the major disadvantage of this type of converter is the the stresses on the power components and Capacitor Charge Time. Furthermore, a control strategy for minimizing the no-load conduction losses is proposed and the transient behavior in case of load steps including output short-circuit is discussed based on digital simulations

Real-Time Inventory Control and Rebalancing in Bike-Sharing Systems by Using a Stochastic Petri Net Model

International audienc

Diagnostic des génératrices asynchrones dans une éolienne a vitesse variable à base d’un observateur de court-circuit statorique

International audienc

Short-Circuit Fault Tolerant Control of a Wind Turbine Driven Induction Generator Based on Sliding Mode Observers

The installed energy production capacity of wind turbines is growing intensely on a global scale, making the reliability of wind turbine subsystems of greater significance. However, many faults like Inter-Turn Short-Circuit (ITSC) may affect the turbine generator and quickly lead to a decline in supplied power quality. In this framework, this paper proposes a Sliding Mode Observer (SMO)-based Fault Tolerant Control (FTC) scheme for Induction Generator (IG)-based variable-speed grid-connected wind turbines. First, the dynamic models of the wind turbine subsystems were developed. The control schemes were elaborated based on the Maximum Power Point Tracking (MPPT) method and Indirect Rotor Flux Oriented Control (IRFOC) method. The grid control was also established by regulating the active and reactive powers. The performance of the wind turbine system and the stability of injected power to the grid were hence analyzed under both healthy and faulty conditions. The robust developed SMO-based Fault Detection and Isolation (FDI) scheme was proved to be fast and efficient for ITSC detection and localization.Afterwards, SMO were involved in scheming the FTC technique. Accordingly, simulation results assert the efficacy of the proposed ITSC FTC method for variable-speed wind turbines with faulty IG in protecting the subsystems from damage and ensuring continuous connection of the wind turbine to the grid during ITSC faults, hence maintaining power quality

The influence of

Typha Australis is a plant that grows abundantly in fresh water. The proliferation of this plant causes health problems, so several measures have been taken to eradicate this problem such as: cutting the plant, coal production. So this article is about the valorisation of this plant as a bio-based material in order to solve the energy problem in the building. In this study, clay was used as a binder with a given percentage. The mixture of clay and Typha was used as an insulation panel and a comparison was made with a conventional habitat without an insulation panel. A dynamic thermal simulation was performed on TRNSYS to evaluate the influence of the use of this insulation panel on the energy consumption in the building. The results of the comparison showed that the use of this insulation panel, which is a mixture of clay and Typha Australis, reduced the energy requirement by 23%, which is a satisfactory result

Current Status of Carbidic Austempered Ductile Iron

Grinding balls in wet ball mill are important consumables in mine grinding equipment, which have poor wear resistance and large consumption. It is imperative to find excellent wear-resistant materials for the grinding balls. Carbidic Austempered Ductile Iron (referred to as CADI) was used as small and medium-sized wet ball mills. This grinding ball has the advantages of less wear, low crushing rate, power saving and low noise. However, the CADI grain boundaries are distributed with net-like eutectic carbides, which seriously damage the continuity of the matrix. In addition, the mechanism of corrosion wear and impact fatigue is lack of research due to complex phase composition and unclear mechanism of phase properties on improving performance. So CADI can’t be applied to the grinding balls in large wet ball mill. Based on the above problems, this paper first analyzed the heteronucleation mechanism and adsorption mechanism of M3C type carbides by using the first principle of microalloying elements, and then verified it by combining with experimental results. Then the thermodynamics and kinetics of austenite homogenization and isothermal transformation of ductile iron containing carbides were analyzed by means of modeling calculation and experiment. On this basis, a new type heat treatment process comprising super-high temperature pretreatment and austempering treatment (S&A treatment) was used to process CADI, which provides a new idea for further improving toughness of CADI. Finally, the CADI corrosion wear and impact fatigue failure mechanism were revealed by analyzing the change rule of the sample surface and cross section after corrosion wear and impact fatigue

Investigation of the length and percentage fiber influence of Typha Australis on biosourced composites

This paper discusses the influence and content of Typha Australis fibers on the thermal and mechanical properties of clay composites. The objective is to find a better combination of length and percentage of fibers. This combination will allow to have a good compromise between thermal and mechanical properties. The results found at the end of this study are conclusive. Indeed, the increase of the length and the percentages of fibres improve the thermal properties but the values of the compressive resistances decrease