La responsabilité environnementale et sociale en tant qu’instrument du développement dur

سعت الجزائر كغيرها من دول العالم إلى تبني مفهوم التنمية المستدامة لما له من مزايا عديدة، إذ يعتبر هذا المفهوم الجديد السبيل الوحيد لضمان تحقيق نوعية حياة جيدة للسكان في الحاضر وللأجيال في المستقبل. ولتحقيق استراتيجية التنمية المستدامة يجب العمل على إحداث التكامل والتناسق بين المسؤولية البيئية للمؤسسة ومسؤوليتها الاجتماعية اتجاه المجتمع مع توفير بيئة وظروف ملائمة لنجاحهما وهذا من أجل تعزيز القدرة التنافسية لاقتصاديات هذه الدول. وللتعرف أكثر على الآثار التي قد تنجم عن المسؤولية البيئية والاجتماعية، قمنا بدراسة حالة عينة من المؤسسات الصناعية الجزائرية.A l’instar des pays du monde, l’Algérie, a adopté le concept du « Développement Durable » pour bénéficier de ses nombreux avantages. Sur le plan chronologique, le concept est récent et est le seul moyen qui peut réaliser une bonne qualité de vie pour les générations actuelles et futures. Afin d’instaurer une stratégie de développement durable, il est nécessaire d'intégrer et d'harmoniser les différentes dimensions de la responsabilité sociale et environnementale, tout en offrant un environnement et des conditions propices à son succès. Il a pour objectif de renforcer la compétitivité des économies de ces pays. Et dans cet article, nous avons mené une étude sur un échantillon d’entreprises industrielles algériennes

Mechanism and Kinetic Parameters of the Thermal Decomposition of Gibbsite Al(OH) 3 by Thermogravimetric Analysis

In this study, the mechanism and the kinetic parameters of the thermal decomposition of gibbsite Al(OH)3 were studied by differential thermogravimetry technique under non-isothermal conditions, between room temperature and 1200 K at heating rates of 5, 10, 15 and 20 The obtained differential thermogravimetry curves show clearly three distinct peaks. The first peak is due to the partial dehydroxylation of gibbsite. Among the 32 types of differential equations of non-isothermal kinetics, we have found that the most suitable mechanism is (A 3/2 : 2/3 ) also called Avrami-Erofeev equation of order 2/3. The values of the activation energy EA and of the pre-exponential factor K are 157 kJ mol −1 and 7.58 × 10 15 s −1 , respectively. The second peak corresponds to the decomposition of gibbsite to boehmite. Decomposition is controlled by the rate of second-order reaction (F2: g(x) = (1 − x) −1 − 1), under the applied conditions. The activation energy EA and pre-exponential factor K correspond to 243 kJ mol −1 and 3.73 × 10 22 s −1 , respectively. The third peak is due to transformation of boehmite to alumina. However the mechanism for such transformation is better described by the 3/2 rate order reaction (F 3/2 : g(x) = (1 − x) −1/2 − 1). In addition, the values of EA and K were determined to be around 296 kJ mol −1 and 1.82 × 10 19 s −1 , respectively. The results of differential thermogravimetry were supplemented by the differential thermal analysis. X-ray powder diffraction analysis was carried out for samples of gibbsite treated at different temperatures between 200 and 1200 • C in 200 • C steps

The effect of ball milling on properties of sintered manganese-doped alumina

Alumina-based compounds have many technological applications and attract great attention even after decades of investigation, due to their good chemical, electrical, and mechanical properties. A mixture of several alumina modifications (α-, κ-, γ-Al2O3) doped with 1 wt% of Mn2O3 was used for this experiment. The powder was mechanically activated for 60 min in an ethanol medium. After compaction, green bodies were sintered in the temperature range from 1200 to 1400 °C. Microstructures of the obtained specimens were investigated by scanning electron microscopy (SEM) and Energy-dispersive X-ray spectroscopy (EDS). The influence of morphological changes on electrical and mechanical properties was examined in detail. We have developed a test fixture and corresponding software for measurement of the relative dielectric permittivity and the loss tangent of ceramic specimens. This new method overcomes the problems of dimensions and shape of samples, as well as the problem of applying silver paste. The accuracy is around 2% for ε'r and 0.003 for tanδ. We demonstrate that the mechanical activation (MA) has the dominant influence on lowering the characteristic temperatures and microstructure development, which further leads to increased permittivity and tensile strength.This is the peer reviewed version of the paper: Filipović, S., Obradović, N., Marković, S., Mitrić, M., Balać, I., Đorđević, A., Pavlović, V.B., 2019. The effect of ball milling on properties of sintered manganese-doped alumina. Advanced Powder Technology 30, 2533–2540. [https://doi.org/10.1016/j.apt.2019.07.033

Deep Feature Pyramid Hashing for Efficient Image Retrieval

Thanks to the success of deep learning, deep hashing has recently evolved as a leading method for large-scale image retrieval. Most existing hashing methods use the last layer to extract semantic information from the input image. However, these methods have deficiencies because semantic features extracted from the last layer lack local information, which might impact the global system’s performance. To this end, a Deep Feature Pyramid Hashing DFPH is proposed in this study, which can fully utilize images’ multi-level visual and semantic information. Our architecture applies a new feature pyramid network designed for deep hashing to the VGG-19 model, so the model becomes able to learn the hash codes from various feature scales and then fuse them to create final binary hash codes. The experimental results performed on two widely used image retrieval datasets demonstrate the superiority of our method

Mechanism and kinetic parameters of the thermal decomposition of gibbsite Al(OH)₃ by thermogravimetric analysis

In this study, the mechanism and the kinetic parameters of the thermal decomposition of gibbsite Al(OH)₃ were studied by differential thermogravimetry technique under non-isothermal conditions, between room temperature and 1200 K at heating rates of 5, 10, 15 and 20°C min¯¹. The obtained differential thermogravimetry curves show clearly three distinct peaks. The first peak is due to the partial dehydroxylation of gibbsite. Among the 32 types of differential equations of non-isothermal kinetics, we have found that the most suitable mechanism is (A_{3/2}: g(x)=[-ln(1-x)]^{2/3}) also called Avrami-Erofeev equation of order 2/3. The values of the activation energy E_{A} and of the pre-exponential factor K are 157 kJ mol¯¹ and 7.58×10¹⁵ s¯¹, respectively. The second peak corresponds to the decomposition of gibbsite to boehmite. Decomposition is controlled by the rate of second-order reaction (F₂: g(x)=(1-x)¯¹-1), under the applied conditions. The activation energy E_{A} and pre-exponential factor K correspond to 243 kJ mol¯¹ and 3.73×10²² s¯¹, respectively. The third peak is due to transformation of boehmite to alumina. However the mechanism for such transformation is better described by the 3/2 rate order reaction (F_{3/2}: g(x)=(1-x)^{-1/2}-1). In addition, the values of E_{A} and K were determined to be around 296 kJ mol¯¹ and 1.82×10¹⁹ s¯¹, respectively. The results of differential thermogravimetry were supplemented by the differential thermal analysis. X-ray powder diffraction analysis was carried out for samples of gibbsite treated at different temperatures between 200 and 1200°C in 200°C steps

Phase Transformation and Sintering of Algeria Clay Powder

Clay is one of the most used natural materials in the ceramic industry with various applications such as pottery, tiles, cement and bricks. The latter are used as a building material because of their excellent thermal and mechanical properties. In the present study, Algerian clay from Al-maathed area, M'sila district, was used to prepare bricks. The chemical composition of the clay was determined using X-ray fluorescence. Firing of clay was carried out in the temperature range 20-1000°C, at different heating rates. The present phases and their transformations, the activation energy, and the sintering mechanism were evaluated using X-ray diffraction, differential thermal analysis, thermogravimetric analysis and dilatometry. The activation energy for the sintering mechanism obtained from non-isothermal treatments is 420 kJ/mol. The value of the Avrami exponent, n, is determined from the shape of the crystallization exothermic dependence. It is related to m parameter (a numerical factor which depends on the dimensionality of crystal growth) obtained by Matusita method. Both of which are about 1.2 for clay sintering. These values indicate that bulk nucleation is dominant in clay sintering by three-dimensional growth, with polyhedron-like morphology controlled by interface reaction

Preparation and Phase Transformation of Mullite-Zirconia from Boehmite and Algerian Halloysite

In this work, mullite-zirconia composite were fabricated by reaction sintering of Algerian halloysite Al₂Si₂O₅(OH)₄, boehmite Al(OOH), and zirconia (ZrO₂) powder using conventional heating. The appropriate amount of the three raw powders was ball milled for 5 h and sintered between 1250 and 1650°C for 2 h. A scanning electron microscope was used to characterize the microstructure of sintered samples. A dilatometer and X-ray diffractometer were used to analyze the formation and transformation of phases. It is found that for the addition of zirconia up to 20wt.% the zirconia phase retains its tetragonal structure. The formation of primary mullite in all samples was complete at 1220°C. The cristobalite started to form at 1350°C, and disappeared at 1500°C in the samples of mullite, and at 1450°C when ZrO₂ was added. The zircon compound ZrSiO₄ started to form at 1350°C and completely disappeared at 1550°C. The increase in ZrO₂ ratio promoted the formation of grains with a spherical shape

Thermal Decomposition Kinetics of Algerian Tamazarte Kaolin by Differential Thermal Analysis (DTA)

In the present study, the kinetics of meta-kaolinite (Al₂O₃·2SiO₂) formation from Algerian Tamazarte kaolin was investigated by using differential thermal analysis. The differential thermal analysis and the thermogravimetric experiments were carried out on samples between room temperature and 1400°C, at heating rates from 10 to 40°C min¯¹. X-ray diffraction was used to identify the phases present in the samples. The activation energies measured by differential thermal analysis from isothermal and non-isothermal treatments using Johnson-Mehl-Avrami methods with Ligero approximation and using Kissinger-Akahira-Sunose methods were around 145 and 159 kJ/mol, respectively. The Avrami parameter n which indicates the growth morphology parameters were found to be almost equal to 1.60, using non-isothermal treatments, and equal to 1.47 using isothermal treatments. The numerical factor which depends on the dimensionality of crystal growth was 1.60 obtained using Matusita et al. equation. The frequency factor calculated using the isothermal treatment is equal to 1.173× 10⁷ s¯¹. Analysis of the results have shown that bulk nucleation was dominant during kaolinite transformation, followed by three-dimensional growth of meta-kaolinite with polyhedron-like morphology, controlled by diffusion from a constant number of nuclei