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Assessing Software Service Quality and Trustworthiness at Selection Time
Limam, N,Boutaba, R IEEE 2010 IEEE transactions on software engineering Vol.36 No.4
<P>The integration of external software in project development is challenging and risky, notably because the execution quality of the software and the trustworthiness of the software provider may be unknown at integration time. This is a timely problem and of increasing importance with the advent of the SaaS model of service delivery. Therefore, in choosing the SaaS service to utilize, project managers must identify and evaluate the level of risk associated with each candidate. Trust is commonly assessed through reputation systems; however, existing systems rely on ratings provided by consumers. This raises numerous issues involving the subjectivity and unfairness of the service ratings. This paper describes a framework for reputation-aware software service selection and rating. A selection algorithm is devised for service recommendation, providing SaaS consumers with the best possible choices based on quality, cost, and trust. An automated rating model, based on the expectancy-disconfirmation theory from market science, is also defined to overcome feedback subjectivity issues. The proposed rating and selection models are validated through simulations, demonstrating that the system can effectively capture service behavior and recommend the best possible choices.</P>
Combination effect of three anti-HSV-2 active plant extracts exhibiting different modes of action
Benzekri Roudaina,Limam Ferid,Bouslama Lamjed 경희대학교 융합한의과학연구소 2020 Oriental Pharmacy and Experimental Medicine Vol.20 No.2
The emergence of multidrug-resistant viruses leads to discover a novel source of drugs or a new strategy to overcome this obstacle. Combined herbal therapies are becoming a promising approach for a better efficiency. In this study, Pistacia lentiscus and Peganum harmala were investigated for their anti HSV-2 activity. Twenty eight organic extracts from different organs were evaluated for their cytotoxicity on Vero cells and their anti HSV-2 activity using the MTT test and the plaque reduction assay, respectively. Peganum harmala methanol seeds extract, Pistacia lentiscus methanol stem and dichloromethane fruit extracts were active on HSV-2 with selectivity index values of 13.19, 51.23 and 10.23, respectively. These active extracts exhibited different mode of action: (1) Peganum harmala methanol seeds extract showed a virucidal action before virus adsorption and penetration, and on the newly formed virions before their release outside infected cells—(2) Pistacia lentiscus methanol stem extract exhibited virucidal effect only before virus adsorption and penetration—(3) Pistacia lentiscus dichloromethane fruit extracts demonstrated virus inhibition up to 7 h post infection. The binary combination of the three active extracts did not improve their individually activity. This report could contribute to prove that combination of active extracts do not necessary increase the initial activity.
A damage model predicting moderate temperature and size effects on concrete in compression
Wiem Ben Hassine,Marwa Loukil,Oualid Limam 사단법인 한국계산역학회 2019 Computers and Concrete, An International Journal Vol.23 No.5
Experimental isotherm compressive tests show that concrete behaviour is dependent on temperature. The aim of such tests is to reproduce how concrete will behave under environmental changes within a moderate range of temperature. In this paper, a novel constitutive elastic damage behaviour law is proposed based on a free energy with an apparent damage depending on temperature. The proposed constitutive behaviour leads to classical theory of thermo-elasticity at small strains. Fixed elastic mechanical characteristics and fixed evolution law of damage independent of temperature and the material volume element size are considered. This approach is applied to compressive tests. The model predicts compressive strength and secant modulus of elasticity decrease as temperature increases. A power scaling law is assumed for specific entropy as function of the specimen size which leads to a volume size effect on the stress-strain compressive behaviour. The proposed model reproduces theoretical and experimental results from literature for tempertaures ranging between 20°C and 70°C. The effect of the difference in the coefficient of thermal expansion between the mortar and coarse aggregates is also considered which gives a better agreement with FIB recommendations. It is shown that this effect is of a second order in the considered moderate range of temperature.
2D numerical investigation of twin tunnels-Influence of excavation phase shift
Djelloul, Chafia,Karech, Toufik,Demagh, Rafik,Limam, Oualid,Martinez, Juan Techno-Press 2018 Geomechanics & engineering Vol.16 No.3
The excavation of twin tunnels is a process that destabilizes the ground. The stability of the tunnel lining, the control of ground displacements around the tunnel resulting from each excavation and the interaction between them must be controlled. This paper provides a new approach for replacing the costly 3D analyses with the equivalent 2D analyses that closely reflects the in-situ measurements when excavating twin tunnels. The modeling was performed in two dimensions using the FLAC2D finite difference code. The three-dimensional effect of excavation is taken into account through the deconfinement rate ${\lambda}$ of the soil surrounding the excavation by applying the convergence-confinement method. A comparison between settlements derived by the proposed 2D analysis and the settlements measured in a real project in Algeria shows an acceptable agreement. Also, this paper reports the investigation into the changes in deformations on tunnel linings and surface settlements which may be expected if the twin tunnels of T4 El-Harouche Skikda were constructed with a tunneling machine. Special attention was paid to the influence of the excavation phase shift distance between the two mechanized tunnel faces. It is revealed that the ground movements and the lining deformations during tunnel excavation depend on the distance between the tunnels' axis and the excavation phase shift.
Shear Bearing Capacity of RC Slabs without Shear Reinforcement: Design Codes Comparison
W. S. A. Nana,T. T. Bui,M. Bost,A. Limam 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.1
For reinforced concrete structures, as beams, slabs or walls, failure under bending is well known and its description and design is relatively internationally agreed. However for the shear failure phenomenon, there is not yet a common agreement at the international level, no consensus is reached on the subject at this time. Many parameters are involved in the shear resistance mechanism and many phenomena coexist. The shear force transfer mechanisms are sometimes complex and difficult to discern. By analyzing the different shear design codes, some shear parameters are taken into account and ignored by others, which makes that a shear effect may be omitted. In addition, different ways are adopted to take into account the different shear parameters. The main purpose of this study is to help the engineering by presenting a comparative study of all the main analytical models for the determination of shear capacity: The EN 1992-1-1:2005 standard (EC2) (CEN, 2005), French National Annex (FD P 18-717, 2013), ACI 318-14 (ACI Committee 318, 2014), fib Model Code 2010 (Fib Model Code 2010, 2012) using level of approximation LoA I and LoA II and (CSA Committee A23.3, 2004) both Modified Compression Field Theory (MCFT) based models, and finally the Critical Shear Crack Theory (CSCT) which is the basis of the Swiss standard SIA 262 (SIA 262, 2003) are all examined. The results obtained are discussed regarding their agreement with eighteen shear experimental results on thick slabs (30 cm, 35 cm, and 40 cm) and thin slabs (10 cm) without shear reinforcement.