Rachid Saadi, Jean‐Marc Pierson and Lionel Brunie
The challenge of pervasive computing consists in offering access to computing services anywhere and anytime with any devices. However, before it becomes a reality, the problems of…
Abstract
The challenge of pervasive computing consists in offering access to computing services anywhere and anytime with any devices. However, before it becomes a reality, the problems of access control and authentication have to be solved, among others. Existing solutions are inadequate without adaptation to this specific environment. Among the promising approaches, the trust paradigm seems to be more flexible than others. We base this proposal on this paradigm to implement a distrust model, so‐called APC (Access Pass Certificate). The main objective of this model is to enable authorized user to roam and to access trusted sites though they are not known locally. A user can claim two kinds of APCs provided by two kinds of sites: the home site (where the user has an account) and the trusted site (that trusts the user). Using these certificates, the user can progressively extend her access scope. This model implements a decentralized mapping policy, where the correspondence between the user’s home profile and her rights in the trusted sites is determined by the trusted site. This distrust model and its implementation are presented in this article where we exhibit its importance for large but controlled access in pervasive environments.
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Karima El Kihel, Hasnae Saadi, Rachid Aharrouch, Abdelmoumen El Antari, Nabil Hachem, Mohamed Madani and Mohammed El Bouziani
The authors investigate the magnetic properties of a mixed spin-3/2 and spin-2 Blume-Capel model on square and cubic lattices with two different single-ion anisotropies.
Abstract
Purpose
The authors investigate the magnetic properties of a mixed spin-3/2 and spin-2 Blume-Capel model on square and cubic lattices with two different single-ion anisotropies.
Design/methodology/approach
To study the critical behavior of a mixed spin-3/2 and spin-2 system, the authors have used a real space renormalization group approximation and specifically the Migdal-Kadanoff technique. The authors give the phase diagrams for two different cases: (1) on the (Δ/|J|, 1/|J|) plane with ΔA = ΔB = Δ, and (2) on the (ΔA/|J|, 1/|J|) and (ΔB/|J|, 1/|J|) planes for selected values of ΔB/|J| and ΔA/|J|, respectively.
Findings
The phase diagrams obtained show that the system exhibits both second- and first-order phase transitions as well as tricritical points for some values of the anisotropies. Moreover, using the variation of the free energy and its derivative at low temperatures, the authors have seen the appearance of first-order transitions at very low temperatures.
Originality/value
Few investigations of mixed spin-3/2 and spin-2 systems with crystal field have been realized. For this reason, the authors use the renormalization group approach to complete the work done on these systems. In absence of an exact solution, this contributes to the synthesis of the approximation results on mixed spins models.
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Wafa Boulagouas, Rachid Chaib and Mebarek Djebabra
Decoupling of pressures ranging from regulatory compliance and stakeholders expectations to business competitiveness and sustainability, companies need to align their…
Abstract
Purpose
Decoupling of pressures ranging from regulatory compliance and stakeholders expectations to business competitiveness and sustainability, companies need to align their environmental strategies with a broader consideration of these influences. This paper aims at developing a dynamic alignment model to enhance the environmental performance that considers the influential pressures based on a multi-criteria decision-making process.
Design/methodology/approach
Authors have proposed a dynamic model for the alignment of the environmental performance based on a hybrid multi-criteria decision-making approach combining the analytic hierarchy process (AHP) and Technique for Order Preference by Similarity to Ideal Solution (TOPSIS). This model considers contemporary strategic dynamism of the environmental performance and provides a methodology to assist companies prioritizing the environmental aspects based on the influential pressures and deciding on the enhancement pathways.
Findings
The proposed model based on a hybrid multi-criteria decision-making process allows prioritizing the environmental aspects considering the allocated weights to the alignment-triggered pressures and draw the way to develop different pathways to improve the alignment.
Practical implications
The proposed dynamic alignment model presents an instrument for the continuous alignment of the environmental performance and an effective management of changes and contributes to minimize gaps and divergences.
Originality/value
In this paper, the environmental performance has been approached through the contemporary strategic dynamism with the deployment of the multi-criteria decision-making techniques to yield an alignment framework for the environmental decision that combines the internal and external approaches for an effective and sustainable improvement of the environmental performance.
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Aliyeh Kazemi, Eun-Seok Kim and Mohammad-Hossein Kazemi
Successful implementation of construction projects is one of the crucial factors for the economic development of every country. The main part of the countries’ capital is…
Abstract
Purpose
Successful implementation of construction projects is one of the crucial factors for the economic development of every country. The main part of the countries’ capital is allocated to civil and infrastructure projects annually, most of which are accomplished with delay. Construction projects are often criticized for overrunning time and budgets. Analyzing the factors causing delay is essential for omitting them and timely implementation of these projects. Due to the importance of oil projects, this study aims to investigate and analyze the factors causing a delay in Iran’s oil construction projects.
Design/methodology/approach
In this research, after a broad literature review, using the fuzzy Delphi method, a total of 75 delay factors were identified under 11 major categories of owner, contractor, consultant, equipment, labor, materials, design, contract and contractual relations, laws and regulations, environmental factors, and managerial factors. Then, by using the best-worst method, the factors were prioritized.
Findings
The results showed that sanction, governmental management systems, weak project management by the contractor, technical and managerial weaknesses of the consultant, financial problems and delay in payment by the owner, low efficiency of the equipment, low productivity of the workforce, changes in laws and regulations, inappropriate organizational structure linking to the project, changes in the design, and changes in the price of materials are the most crucial factors causing a delay in Iran’s oil construction projects.
Research limitations/implications
These findings are expected to have significant contributions to Iran’s oil construction industry in controlling the time overruns in construction contracts.
Originality/value
The main contribution of this study is to develop a comprehensive framework in which, causes of delay in Iran’s oil construction projects are addressed and prioritized.
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Xin Zhou, Wenbin Zhou, Yang Zheng Zhang, Meng-Ran Li, Haijing Sun and Jie Sun
This paper aims to study the corrosion inhibition behavior of imidazopyridine and its three derivatives on brass.
Abstract
Purpose
This paper aims to study the corrosion inhibition behavior of imidazopyridine and its three derivatives on brass.
Design/methodology/approach
The authors performed weight loss experiments, electrochemical experiments including the polarization curve and electrochemical impedance spectrum, corrosion morphology observation using scanning electron microscope (SEM) and atomic force microscope (AFM) and surface composition analysis via X-ray photoelectron spectroscopy (XPS) to analyze the corrosion inhibition behavior of imidazopyridine and its three derivatives on brass by using quantum chemical calculation (Gaussian 09), molecular dynamics simulation (M-S) and Langmuir adsorption isotherm.
Findings
According to the results, imidazole-pyridine and its derivatives were found to be modest or moderately mixed corrosion inhibitors; moreover, they were spontaneously adsorbed on the metal surface in a single-layer, mixed adsorption mode.
Originality/value
The corrosion inhibition properties of pyrazolo-[1,2-a]pyridine and its derivatives on brass in sulfuric acid solution were analyzed through weight loss and electrochemical experiments. Moreover, SEM and AFM were simultaneously used to observe the corrosion appearance. Furthermore, XPS was used to analyze the surface. Then, Gaussian 09 and M-S were combined along with the Langmuir adsorption isotherm to investigate the corrosion inhibition mechanism of imidazole-[1,2-a]pyridine and its derivatives.