Rafic Younes

• Professor
• Head of Faculty at Lebanese University

This paper provides a recent overview of the exact, approximate, and hybrid optimization methods that handle Multi-Objective Mixed-Integer Non-Linear Programming (MO-MINLP) problems. Both the domains of exact and approximate research have experienced significant growth, driven by their shared goal of addressing a wide range of real-world problems....

In the context of global efforts to mitigate climate change by pursuing sustainable energy sources, wind energy has emerged as a critical contributor. However, the wind energy industry faces substantial challenges in maintaining and preserving the integrity of wind turbine blades. Timely and accurate detection and classification of blade faults, en...

Renewable energy has known spectacular development in the last decades as a solution to the climate change effect. Wind energy is one of the most popular technologies for power generation. However, the variable operation and extreme meteorological conditions challenge integrating this technology, especially in cold climate regions. These conditions...

Vibration is one of the most dangerous phenomena that happens to a structure. It leads to premature fatigue and eventually failure, with potentially fatal consequences. A smart structure is an excellent solution to this problem; it adds an actuator, a sensor, and an appropriate control law to the system to reduce/eliminate the vibration. This study...

Wind energy has been playing a pivot role in replacing the traditional energy sources. This emerging paradigm has proved itself as a good candidate among all renewable energy sources. Although the exponential growth of the wind industry, wind turbines still suffer from blade icing especially in cold regions. Blade icing disturbs aerodynamic perform...

Reinforced concrete bridges constitute the major part of existing bridges. The purpose of this paper is to present a serviceability evaluation methodology for RC bridges under probabilistic conditions. It will be based on analytical calculations with no need to complex modeling or advanced software. For this purpose, a realistic traffic model is si...

The installation of wind energy increased in the last twenty years, as its cost decreased, and it contributes to reducing GHG emissions. A race toward gigantism characterizes wind turbine development, primarily driven by offshore projects. The larger wind turbines are facing higher loads, and the imperatives of mass reduction make them more flexibl...

Wind-generated electricity has increased continuously for the last decades and will continue to progress for the next years. Wind energy production is a mature technology with over 600GW installed capacity in the world. The operation of wind farms presents critical challenges to maintain the lowest possible cost of energy. It is essential to detect...

Solving Multi-Objective Mixed Integer NonLinear Programming (MO-MINLP) problems is a point of interest for many researchers as they appear in several real-world applications, especially in the mechanical engineering field. Many researchers have proposed using hybrids of metaheuristics with mono-objective branch and bound. Others have suggested usin...

Hyperspectral imaging is a technique used to collect the same scene with different wavelengths, achieving both high spectral and spatial resolution. Hyperspectral imaging plays an important role in several scenarios involving target detection, among which landmine detection is a very challenging one. In this work, we developed a procedure based on...

The real response of a given structure, such as deflection, generally differs from prediction obtained from theoretical models. Hence, the need of periodic or long-term structural monitoring has become mandatory. The present paper describes an approach to localize the most suitable period to perform deflection monitoring in case of reinforced concr...

Structural reliability is now the leading method in the field of design optimization and assessment of civil engineering structures since it offers a rational treatment of the uncertainties in this kind of studies. However, structural reliability problems become more complex with time due to the high number of random variables leading to very compl...

Despite the enhancement in the wind energy sector, the wind turbine industry still faces certain limitations due to some manufacturing and environmental factors. Blades are one of the major components of the wind turbine. During their lifetime, these blades are susceptible to deterioration and normal wear and tear that limit their efficiency and re...

A great amount of attention has been given to the evaluation of the permeability tensor and several methods have been implemented for this purpose: experimental methods, as well as numerical and analytical methods. Numerical simulation tools are being seriously developed to cover the evaluation of permeability. However, the results are still far fr...

In this work, we study the effect of uncertainties modeling and the choice of objective function on the results of optimization design problems in deterministic and probabilistic contexts. Uncertainties modeling are studied in two cases identified in the literature. The results show how the choice of two different objective functions which lead to...

This paper proposes a guide to help designer to formulate the optimization under uncertainty in mechanical design problem. An efficient tool based on the necessary conditions for each optimization under uncertainty type is introduced here. This tool is capable to guide the designer to choose between different types of optimization under uncertainty...

In this paper we present a new hybrid meta heuristic by combining Multi-objective bat algorithm (MOBA) and variable neighborhood search (VNS). The hybrid meta heuristic is coupled with response surface methodology (or meta modeling) to solve the mechanical multi-objective optimization problem of hat stiffened composite panel. The optimization crite...

The preshaped curved beam is used as bistable mechanism in MEMS, its behavior is characterized by the snapping forces and stresses that evolve during deflection between the two sides of buckling. Based on analytical models, the influence of variating the material and dimension parameters on the behavior of the curved beam is analyzed. The limit of...

Road bridges are exposed to stochastic traffic loadings that are not simply determined. The international codes for the design and assessment of highway bridges provide some standard trucks that can be used in the design process. Knowing that the traffic can vary considerably from one bridge to another, standard trucks may lead to poorly estimate t...

Diesel generators are the main source of electrical energy that supply most of the remote isolated areas in the world. Unfortunately, these motors still pose enormous technical, financial and environmental challenges. Therefore, the combination of these generators with renewable sources like wind energy in a wind-diesel hybrid system (WDS) could re...

Unlike the majority of Canadian population, which benefits from reliable, guaranteed and affordable electricity, most Canadian remote communities do not have these benefits because they rely on locally generated electricity. Diesel generators are the main sources of electrical energy that supply most of these remote isolated areas. The operation an...

A macro rectangular-channel flat-plate solar thermal collector is designed and examined in this study. It consists of a set of adjacent macro rectangular channels formed between the upper, lower, and fin-parts of an absorber plate, thus, overcoming the necessary welding between the absorber plate and riser tubes used in conventional flat-plate coll...

Unmanned Aerial Vehicles (UAVs) offer a wide range of interesting military and commercial applications at reduced costs. A couple of their more interesting characteristics include: They are capable of hovering and flying at high and low speeds, and they can move in any direction and take off and land vertically. A very promising class of these vehi...

The concept of integrated energy management is presented in this study. It defines a global strategy for the management and control of an energy system following five steps, namely, i) selection of resources and technologies, ii) mathematical modeling, iii) optimal sizing, iv) optimal references and v) operational control. First, the above-mentione...

COMSOL Multiphysics is a comprehensive simulation software environment for a wide range of applications. COMSOL has an interactive interface that facilitates the modeling procedure and allows an easy coupling of different physical processes. The Subsurface Flow module extends the COMSOL modeling environment to applications related to fluid flow in...

Smart buildings concept aims at the use of the smart technology to reduce energy consumption as well as improvement of the comfort conditions and users’ satisfaction. It is based on the use of smart sensors to follow both outdoor and indoor conditions as well as software for the control of comfort and security devices. The optimal control of the en...

COMSOL Multiphysics is a comprehensive simulation software environment for a wide range of applications. COMSOL has an interactive interface that facilitates the modeling procedure and allows an easy coupling of different physical processes. The Subsurface Flow module extends the COMSOL modeling environment to applications related to fluid flow in...

The performance of a flat-plate solar collector is usually assessed by its efficiency. This efficiency is normally defined on a steady-state basis, which makes it difficult to correctly track the instantaneous performance of the collector in various case-studies. Accordingly, this paper proposes an improved definition of instantaneous efficiency of...

Permeability reflects the ease of flow inside a composite fabric. A predictive model has been developed to estimate the unidirectional permeability in both, the warp and weft directions, for a family of non-crimped and 3D orthogonal fabrics. The model is based on an analytical solution derived from previous studies, in which the microscopic permeab...

Cet article présente une thèse en cotutelle entre l’université de technologie de Troyes et l’université Libanaise. Cette thèse traite des problèmes d’optimisation en ingénierie mécanique en prenant en compte les incertitudes. L’objectif est de proposer une démarche globale pour résoudre ces problèmes permettant d’améliorer les techniques actuelles...

This article presents a newly proposed selection process for genetic algorithms on a class of unconstrained optimization problems. The k-means genetic algorithm selection process (KGA) is composed of four essential stages: clustering, membership phase, fitness scaling and selection. Inspired from the hypothesis that clustering the population helps...

This article is the first of its kind that treats hat stiffened panel in reliability based optimization (RBO). This panel is used in aerospace and marine structure. Along RBO, a deterministic optimization of this panel is performed. These optimization methods are based on a polynomial metamodel. Panel optimization aims to maximize its rigidity and...

With urban growth, the city's energy consumption continues to increase. In France, the building sector is the largest consumer of energy with a share of about 45% of which 73% for heating and air conditioning. This large consumption contributes to the increase in the greenhouse gases emission. Hence, France has committed to reduce the energy consum...

In this comparative study, convenient analytical models evaluating the permeability of unidirectional fibrous media towards normal and parallel flow are selected. These models are compared with respect to available data early published. Static and transient mode simulations are launched in order to filter out the consistent bibliography values; ana...

Modeling Density Driven Flow (DDF) in unsaturated porous media requires the coupling between the Richards and the mass transport equations. Due to its nonlinearity and intrinsic complexity, the numerical solution of such a coupled system of equations has not been greatly investigated in the literature. Most of the exiting numerical solutions are ba...

Landmines are now a daily threat in Afghanistan, Angola, Bosnia, Cambodia, Chechnya, Croatia, Iraq, Lebanon, Mozambique, Nicaragua, Somalia, and dozens of other countries. Mines recognize no cease-fire and long after the fighting has stopped they continue to hurt or kill Mines also render large tracts of agricultural land unusable, wreaking environ...

This paper is intended to provide an introduction to the issue of landmine contamination, crisis, legacy, and action. We conduct an analysis of mine action national and international programs. Before proposing the use of new technologies, it is important to review the background of the mine action sector since its first inception. These notes set o...

Due to the incredible growth of high dimensional datasets, we address the problem of unsupervised methods sensitive to undergoing different variations, such as noise degradation, and to preserving rare information. Therefore, researchers nowadays are forced to develop techniques to meet the needed requirements. In this work, we introduce a dimensio...

Hyperspectral imaging is a trending technique in remote sensing that finds its application in many different areas, such as agriculture, mapping, target detection, food quality monitoring, etc. This technique gives the ability to remotely identify the composition of each pixel of the image. Therefore, it is a natural candidate for the purpose of la...

The design of harbours, as with any other system design, must be an optimization process. In this study, a global examination of the different constraints in coastal engineering was performed and an optimization problem was defined. The problem has multiple objectives, and the criteria to be minimized are the structure cost and wave height disturba...

The hybrid cooling system has proved to be an energy saving technology for building air conditioning. Numerous systems combining different cooling processes or cooling machines have been proposed and investigated in the literature. A properly selected hybrid cooling system offers a great reduction in energy consumption and a coefficient of performa...

In this paper we present a new hybrid meta heuristic by combining Multi-objective bat algorithm (MOBA) and variable neighborhood search (VNS). The hybrid meta heuristic is coupled with response surface methodology (or meta modeling) to solve the mechanical multi-objective optimization problem of hat stiffened composite panel. The optimization crite...

Over the years, several meta-heuristic algorithms were proposed and are now emerging as common methods for constrained optimization problems. Among them, genetic algorithms (GA's) shine as popular evolutionary algorithms (EA's) in engineering optimization. Most engineering design problems are difficult to resolve with conventional optimization algo...

Within the last 20 years, wind turbines have reached matured and the growing worldwide wind energy market will allow further improvements. In the recent decades, the numbers of research papers that have applied optimization techniques in the attempt to obtain an optimal design have increased. The main target of manufacturers has been to minimize th...

Many remote areas around the world are isolated, for various reasons, from electricity networks. They are usually supplied with electricity through diesel generators. The cost of operation and transportation of diesel fuel in addition to its price have led to the procurement of a more efficient and environmentally greener method of supply. Various...

This study presents an analytical modeling of the mechanical behavior of textile composites. The main objective of this study is to evaluate in-plane and out of plane ultimate strengths for different types of 2D and 3D fabric-reinforced polymer. The proposed analytical model consists of a homogenization method, a failure criterion, and a damaged st...

In this paper, physical models for the cooling and the lubricating systems for marine diesel engine have been developed. The main purpose of this modeling is to integrate some possible faults that may be produced, and then to analyze their effects on the overall marine diesel engine during operation. Faults may appear in the model as the variation...

Étant donné la croissance à l’échelle mondial (et au Québec en particulier), l’augmentation des besoins énergétiques, les exigences législatives ainsi que les limitations physiques et géométriques, il devient nécessaire de fournir aux concepteurs un outil de décision convenable.

In this paper, a unique single zone combustion model is proposed to predict Diesel engine's performance, pressure, and temperature based on the conservation of mass and energy. In order to simulate all phases of combustion, the proposed model takes in consideration the dynamics of the intake and exhaust gas through the valves, the ignition delay, t...

Over the years, several meta-heuristic algorithms were proposed and are now emerging as common methods for constrained optimization problems. Among them, genetic algorithms (GA's) shine as popular evolutionary algorithms (EA's) in engineering optimization. Most engineering design problems are difficult to resolve with conventional optimization algo...

This paper presents a literature review on most of the faults and their models that are considered on a diesel engine. Several faults that may be produced on diesel engine have been analyzed, classified, modeled, and their influences on the global system have been shown. Thus, this paper aims to prepare an important data base on diesel engine fault...

The search for more efficient and sustainable renewable energies is rapidly growing. Throughout the years, wind turbines matured towards a lowered cost-of-energy and have grown in rotor size therefore stretched the role of composite materials that offered the solution to more flexible, lighter and stronger blades. The objective of this paper is to...

Rare events can potentially occur in many applications, particularly in hyperspectral image analysis. In this work, we focus on the rare event preservation rate of the different dimension reduction approaches. The objective is to test whether the rare event is preserved after dimension reduction, or not. This paper introduced an improvement on the...

Our work focuses about the determination of the most useful bands of the spectrum for the detection of the landmines and test unsupervised and supervised classification algorithms that could help to achieve our goal.

Electricity in Canadian remote areas is, historically, produced using Diesel generators. Its total production cost is very high not only due to inherent cost of fuel but also due to transportation and maintenance costs. Moreover, the use of fossil fuels is a significant source of greenhouse gas emissions. Hybrid systems that combine wind turbines a...

This paper presents a simulator model of a marine diesel engine based on physical, semi-physical, mathematical and thermodynamic equations, which allows fast predictive simulations. The whole engine system is divided into several functional blocks: cooling, lubrication, air, injection, combustion and emissions. The sub-models and dynamic characteri...

This paper proposes a new method for gas concentration measurement. The method relies on the principle of plasma emissions of gases under high voltage. We proposed a method that uses digital image processing to model the color mixing of the emissions of the gases. The application of the inverse model allows us to get the percentages of each gas in...

Tumors in humans are believed to be caused by a sequence of genetic abnormality. Understanding these sequences is important for improving cancer treatments. Biologists have uncovered some of the most basic mechanisms by which normal stem cells develop into cancerous tumors. These biological theories can then be transformed into mathematical models....

The calibration of the model is one of the most important steps in the development of models of engineering systems. A new approach is presented in this study to calibrate a complex multi-domain system. This approach respects the real characteristics of the circuit, the accuracy of the results, and minimizes the cost of the experimental phase. This...

The influence of hydrodynamic model selection on the optimal layout of fixed breakwaters found in harbour design has been tested. Results from different models were compared. The mild slope equation was considered as reference. An extended mild slope equation taking into account the slope and curvature of rapid variation in the bathymetry was exami...

This paper presents the dynamic modeling of a domestic hybrid water heating system. The system is composed of a solar collector, a heat pump water heater, a wind turbine, a battery and a hot water storage tank. Both air-source and geothermal-heat pumps are investigated. Detailed mathematical dynamic models of the individual components are presented...

The work presented in this paper deals with the description of an analytic modeling of the neuromusculoskeletal system responsible for the finger movement. This simulation task is complex due to the interacting processes (physiological and biomechanical) represented by muscles, joints and bones. In this study, we focused on the presentation of a co...

This paper gives an overview about the state of the art and novel technologies used in gas sensing. It also discusses the miniaturization potential of some of these technologies in a comparative way. Design/methodology/approach - In this article we state the most of the methods used in gas sensing discuss their advantages and disadvantages and at l...

This paper addresses an optimisation problemof the design of detached breakwaters planned at offshore terminals. The approach aims to minimize the cost of the protection struc-ture where the wave height in the terminal area is consid-ered to be the main constraint. A genetic algorithm is used to solve the problem where the fitness function consists...

Biologists have uncovered some of the most basic mechanisms by which normal cells develop into cancerous tumors. These biological theories can be transformed into adequate mathematical models. For this reason, we attempt to study the evolution of cancer cells using the GWBP. The purpose of this paper is to study how the genetic algorithm (GA) can b...

This paper presents a dynamic simulation model to predict the performance of an ASHPWH (air source heat pump water heater). The developed model is used to assess its performance in the Lebanese context. It is shown that for the four Lebanese climatic zones, the expected monthly values of the average COP (coefficient of performance) varies from 2.9...

Rare events can potentially occur in many applications, particularly in hyper spectral image analysis. When manifested as opportunities to be exploited, such events become of paramount significance. Due to their sporadic nature, the information-bearing spectral vectors associated with rare events often lie in a large set of irrelevant signals and a...

This paper deals with Diesel engine control. More precisely, a model-based approach is considered to stabilize engine speed around a defined value. The model taken into account is nonlinear and contains explicitly the expression of fuel conversion efficiency. In general in the literature, this experimentally obtained quantity is modeled with either...

The aim of the proposed work is to evaluate, by simulation, the introduction of a data fusion process from a HD-sEMG grid (8×8) to improve the muscle force estimation from sEMG signal. For this purpose, twelve electrode arrangements are combined to dimension reduction technique (PCA or channel averaging) to obtain a monodimensional sEMG signal. Aft...

In the wind industry, the current trend is towards building larger and larger turbines. This presents additional structural challenges and requires blade materials that are both lighter and stiffer than the ones presently used. This study is aimed to aid the work of designing new wind turbine blades by providing a comparative study of different com...

We address the problem of unsupervised band reduction in multispectral imagery. We propose to use a new hybridization of dimensionality reduction method by combining two categories of bands selection method with projection method and apply it to multispectral data. The algorithm employs the concepts of fuzziness and belongingness (Fuzzy K-means) to...

La production d'eau chaude sanitaire contribue à une forte consommation d'énergie dans le bâtiment. Dans le but de diminuer la consommation d'énergie résidentielle, un système de chauffage d'eau hybride est proposé et modélisé. La performance énergétique de ce système est évaluée dans des conditions d’utilisation à Beyrouth, capitale du Liban. Les...

This paper presents a review of the energy status, conventional and renewable, in Lebanon and illustrates their problems with the suggested recommendations. In addition, a detailed review of the principal directorates of the electricity of Lebanon Company (EDL) is also presented all along with the existing problems and recommended solutions. An eco...

This paper presents a brief review of the conventional and renewable energy statuses, in Lebanon, as well as of the principal problems facing the electricity of Lebanon Company (EDL). In addition, an analytical-critical review of the latest three official Lebanese electricity plans is presented. Furthermore, two future electricity generation plan-s...

The power generation for remote areas is historically ensured with Diesel engines generators. The economical cost of energy is therefore very high not only due to inherent cost of fuel but also due to transportation and maintenance costs. The environmental cost of energy is also high as the use of fossil fuels for electricity generation is a signif...

This work is a part of a research program that aims to modify a conventional internal combustion engine and turn it into a hybrid pneumatic–combustion engine. The hybrid pneumatic–combustion engine should be able to convert mechanical energy into compressed air and convert compressed air back into mechanical energy. The potential application for th...

Dimensionality reduction is a big challenge in many areas. In this research we address the problem of high-dimensional hyperspectral images in which we are aiming to preserve its information quality. This paper introduces a study stability of the non parametric and unsupervised methods of projection and of bands selection used in dimensionality red...