An Estimation of Cargo Handling Service Costs: Case of the Port of Saint-Brieuc, France

Souhir ABBES 국제이네비해양경제학회 2017 International Journal of e-Navigation and Maritime Vol.8 No.1

The estimation of key indicators in a firm’s cost structure, such as marginal costs, economies of scale and elasticity of substitution are essential to defining the optimal pricing policy, investment and the regulation of ports. However, only a few studies have focused on the estimation of such indicators due to the unavailability of cost data on seaports. In addition, other port cost studies focused on all port activities. The output is measured as a physical product rather than as a service product. The main purpose of this paper is then to concentrate on one service, cargo handling in the port of Saint-Brieuc, and to examine the real composition of its costs. The estimation of a translog cost function suggested that the port may have an over employment of administrative staff in the handling service and a limited capacity when it comes to efficiency in the long run. The results also indicated increasing returns to scale that may suggest that the application of pricing at a marginal cost might not aid the total recovery of the outlay. These results are useful from an operational as well as an investment policy perspective.

Microrheological study of PVA–borax physical gel: effects of charge screening

Chayma Abbes,Marouen Zammali,Hasna Faten Mahjoub,Tahar Othman 한국고분자학회 2023 Macromolecular Research Vol.31 No.7

The charge screening effects on the viscoelasticity and the gelation properties of the mixture poly(vinyl alcohol) (PVA) and borax transient physical hydrogel was studied by diffusing-wave spectroscopy microrheology (DWS) and classical rheometry. The critical gel point of PVA–borax hydrogel was demonstrated at the high frequency range according to the uniqueness criterion of Winter and Chambon (WC) and was found to decrease with increasing sodium chloride (NaCl) concentrations. Time-cure superposition strategy has been adopted to elucidate the scaling laws that govern the sol–gel transition of PVA–borax hydrogel. Then, the Rubinstein and Semenov (R–S) regime was established allowing the estimation of the size of the largest relaxed cluster Rz near the gel point. The increase of the ionic strength within the PVA–borax network was found to induce a decrease of Rz. The combination of these findings suggested that NaCl triggered a contraction of PVA–borax physical network as a result of the charge screening effect, leading to the enhancement of the associativity as well as the density of the hydrogel. This work is expected to provide an insight into the behavior of physical gels within biological systems with high ionic strengths.

Flexural behaviour of steel beams reinforced by carbon fibre reinforced polymer: Experimental and numerical study

Hassaine Daouadji Tahar,Abbes Boussad,Rabahi Abderezak,Benferhat Rabia,Abbes Fazilay,Adim Belkacem 국제구조공학회 2019 Structural Engineering and Mechanics, An Int'l Jou Vol.72 No.4

The paper presents the results of an experimental and numerical programme to characterize the behaviour of steel beams reinforcement by composite plates. Important failure mode of such plated beams is the debonding of the composite plates from the steel beam due to high level of stress concentration in the adhesive at the ends of the composite plate. In this new research, an experimental and numerical finite element study is presented to calculate the stresses in the sika carbodur and sika wrap reinforced steel beam under mechanical loading. The main objective of the experimental program was the evaluation of the force transfer mechanism, the increase of the load capacity of the steel beam and the flexural stiffness. It also validated different analytical and numerical models for the analysis of sika carbodur and sika wrap reinforced steel beams. In particular, a finite element model validated with respect to the experimental data and in relation to the analytical approach is presented. Experimental and numerical results from the present analysis are presented in order to show the advantages of the present solution over existing ones and to reconcile debonding stresses with strengthening quality.

Dynamic analysis for anti-symmetric cross-ply and angle-ply laminates for simply supported thick hybrid rectangular plates

Benhenni, Mohamed Amine,Daouadji, Tahar Hassaine,Abbes, Boussad,Adim, Belkacem,Li, Yuming,Abbes, Fazilay Techno-Press 2018 Advances in materials research Vol.7 No.2

In this paper, static and vibration analysis for anti-symmetric cross-ply and angle- ply carbon/glass hybrid laminates rectangular composite plate are presented. In this analysis, the equations of motion for simply supported thick laminated hybrid rectangular plates are derived and obtained through the use of Hamilton's principle. The closed-form solutions of anti-symmetric cross-ply and angle- ply laminates are obtained using Navier solution. The effects of side-to-thickness ratio, aspect ratio, and lamination schemes on the fundamental frequencies loads are investigated. The study concludes that shear deformation laminate theories accurately predict the behavior of composite laminates, whereas the classical laminate theory over predicts natural frequencies. The excellent accuracy of the present analytical solution is confirmed by making some comparisons of the present results with those available in the literature. It can be concluded that the proposed theory is accurate and simple in solving the free vibration behaviors of anti-symmetric cross-ply and angle- ply hybrid laminated composite plates.

Analytical analysis of the interfacial shear stress in RC beams strengthened with prestressed exponentially-varying properties plate

Rabia, Benferhat,Abderezak, Rabahi,Daouadji, Tahar Hassaine,Abbes, Boussad,Belkacem, Adim,Abbes, Fazilay Techno-Press 2018 Advances in materials research Vol.7 No.1

In this paper, a closed-form rigorous solution for interfacial shear stress in simply supported beams strengthened with bonded prestressed E-FGM plates and subjected to an arbitrarily positioned single point load, or two symmetric point loads is developed using linear elastic theory. This improved solution is intended for application to beams made of all kinds of materials bonded with a thin plate, while all existing solutions have been developed focusing on the strengthening of reinforced concrete beams, which allowed the omission of certain terms. The theoretical predictions are compared with other existing solutions. Finally, numerical results from the present analysis are presented to study the effects of various parameters of the beams on the distributions of the interfacial shear stresses. The results of this study indicated that the E-FGM plate strengthening systems are effective in enhancing flexural behavior of the strengthened RC beams.

Elastic analysis of interfacial stress concentrations in CFRP-RC hybrid beams: Effect of creep and shrinkage

Abderezak, Rabahi,Daouadji, Tahar Hassaine,Abbes, Boussad,Rabia, Benferhat,Belkacem, Adim,Abbes, Fazilay Techno-Press 2017 Advances in materials research Vol.6 No.3

A simple closed-form solution to calculate the interfacial shear and normal stresses of retrofitted concrete beam strengthened with thin composite plate under mechanical loads including the creep and shrinkage effect has been presented in this paper. In such plated beams, tensile forces develop in the bonded plate, and these have to be transferred to the original beam via interfacial shear and normal stresses. Consequently, debonding failure may occur at the plate ends due to a combination of high shear and normal interfacial stresses. These stresses between a beam and a soffit plate, within the linear elastic range, have been addressed by numerous analytical investigations. Surprisingly, none of these investigations has examined interfacial stresses while taking the creep and shrinkage effect into account. In the present theoretical analysis for the interfacial stresses between reinforced concrete beam and a thin composite plate bonded to its soffit, the influence of creep and shrinkage effect relative to the time of the casting, and the time of the loading of the beams is taken into account. Numerical results from the present analysis are presented both to demonstrate the advantages of the present solution over existing ones and to illustrate the main characteristics of interfacial stress distributions.

Elastic analysis of interfacial stresses in prestressed PFGM-RC hybrid beams

Abderezak, Rabahi,Rabia, Benferhat,Daouadji, Tahar Hassaine,Abbes, Boussad,Belkacem, Adim,Abbes, Fazilay Techno-Press 2018 Advances in materials research Vol.7 No.2

In this paper, the problem of interfacial stresses in damaged reinforced concrete beams strengthened with bonded prestressed functionally graded material plate and subjected to a uniformly distributed load, arbitrarily positioned single point load, or two symmetric point loads is developed using linear elastic theory. The adopted model takes into account the adherend shear deformations by assuming a linear shear stress through the depth of the damaged RC beam. This solution is intended for application to beams made of all kinds of materials bonded with a thin FGM plate. The results show that there exists a high concentration of both shear and normal stress at the ends of the functionally graded material plate, which might result in premature failure of the strengthening scheme at these locations. Finally, numerical comparisons between the existing solutions and the present new solution enable a clear appreciation of the effects of various parameters of the beams on the distributions of the interfacial stresses.

A high-order closed-form solution for interfacial stresses in externally sandwich FGM plated RC beams

Chedad, Abdebasset,Daouadji, Tahar Hassaine,Abderezak, Rabahi,Belkacem, Adim,Abbes, Boussad,Rabia, Benferhat,Abbes, Fazilay Techno-Press 2017 Advances in materials research Vol.6 No.4

In this paper, an improved theoretical solution for interfacial stress analysis is presented for simply supported concrete beam bonded with a sandwich FGM plate. Interfacial stress analysis is presented for simply supported concrete beam bonded with a sandwich plate. This improved solution is intended for application to beams made of all kinds of materials bonded with a thin plate, while all existing solutions have been developed focusing on the strengthening of reinforced concrete beams, which allowed the omission of certain terms. It is shown that both the normal and shear stresses at the interface are influenced by the material and geometry parameters of the composite beam. A numerical parametric study was performed for different simulated cases to assess the effect of several parameters. Numerical comparisons between the existing solutions and the present new solution enable a clear appreciation of the effects of various parameters. The results of this study indicated that the FGM sandwich panel strengthening systems are effective in enhancing flexural behavior of the strengthened RC beams.

Pseudo Bond Graph Model of Thermal Transfers Supported by an Outside Cold Airflow of a Refrigerator to Improve Its Performance

Emna Aridhi,Mehdi Abbes,Abdelkader Mami 대한설비공학회 2017 International Journal Of Air-Conditioning and Refr Vol.25 No.4

This paper aims to prove the efficiency of using the naturally free and abundant cold airflow to improve the cooling inside a household refrigerator and to reduce the energy consumption in Nordic and high altitude countries. The cold airflow is spread out in a cavity covering the side wall of the appliance. This cavity is also connected to the cold outdoor environment through inlet and outlet ducts. For that purpose, a pseudo bond graph (BG) model is proposed to model this installation. It represents the thermal transfers by forced convection in the cavity and the ducts with the ambient and outdoor surroundings. The internal air temperature is computed according to the evaporator temperature and the outside cold airflow that is also computed according to the outside temperature. The simulation results show that the cooling process was speeded up by about 39% and the duration of the compressor functioning was reduced by about 10h and 8min, which allows reducing the total energy use by 0.88kWh, and thus achieving an energy saving of about 34.61%. Experimental data of the outside airflow temperature in Canada during 28 hours in January 2017 are used in the model and allow an energy saving of about 40%.

Pseudo Bond Graph Modeling and Experimental Investigation of Thermal Transfers Inside a Household Refrigerator

Emna Aridhi,Mehdi Abbes,Abdelkader Mami 대한설비공학회 2016 International Journal of Air-Conditioning and Refr Vol.24 No.2

This paper proposes a pseudo bond graph model of thermal transfers by natural convection inside a household refrigerator. It has two inputs: the ambient temperature and the temperature at the level of the evaporator wall. The latter assesses the functioning of the compressor cycles. A performance comparison, with the experimental data, was carried out in order to verify the model, in which, real measurements are used to modulate the evaporator temperature source. The simulation results show the effectiveness of the proposed approach.