In this study, we investigate a production planning problem in hybrid manufacturing remanufacturing production system. The objective is the determine the best mix between the manufacturing of new products, and the remanufacturing of recovered products, based on economic and environmental considerations. It consists to determine the best manufacturing and remanufacturing plans to minimising the total economic cost (start-up and production costs of new and remanufactured products, storage costs of new and returned products and disposal costs) and the carbon emissions (new products, remanufactured products and disposed products). The hybrid system consists of a set of machines used to produce new products and remanufactured products of different grades (qualities). We assume that remanufacturing is more environmentally efficient, because it allows to reduce the disposal of used products. A multi-objective mathematical model is developed, and a non dominated sorting genetic algorithm (NSGA-II) based approach is proposed. Numerical experience is presented to study the impact of carbon emissions generated by new, remanufactured and disposed products, over a production horizon of several periods.
Cooperation in distribution network has attracted the interest of researchers. In this study we analyse an inventory problem in distribution network, where we propose a cooperative platform that allow the members of the network to share and use local inventory of other members to meet their local demand. We develop a MIP models representing the traditional network and the network with the cooperative platform. Then we solve it using LINGO solver. We found that the proposed approach has reduced the total cost of the network and reduce the overstock and stock-out situation, which lead to improve the quality of service.
Alors que la professionnalisation de toute formation exige la prise en considération des besoins des formés et des exigences de la profession, l’Algérie continue d’importer des offres de formation con\c cues dans d’autres pays et dédiées à des publics particuliers. Distincts de ces publics, les formés algériens se préparant à enseigner les langues étrangères ont besoin de formations plus adaptées à leurs attentes et à celles des acteurs impliqués. Ce résultat, auquel nous avons abouti, suite à l’analyse des maquettes de formation, nous a conduits à proposer des réflexions et un profil psychologique-type pouvant améliorer la formation des enseignants et leur future pratique.
Plusieurs causes sont à l’origine du déclin de l’enseignement de la littérature – et des disciplines connexes qui s’y rapportent – au sein des départements de lettres et de langues en Algérie. On accuse traditionnellement l’évolution technocratique de cette société du moindre effort où le divertissement meuble le quotidien du plus grand nombre. On parle également des crises socio-économiques qui nous enlisent dans un rapport de consommation effrénée et nous astreignent à une focalisation permanente sur la survie. Enfin, certains théoriciens dénoncent les réseaux sociaux ; véritables armes de contrôle et de manipulation des masses, ils nivelleraient constamment vers le bas. Et si la solution se trouvait du côté de cette même littérature ? Et si la poétique, discipline qui traite de la littérarité, nous permettait de fuir ce chaos, de renouer avec des idéaux et de restaurer une verticalité ?
Objective: The aim of our work is to study the links between anthropometric parameters and body composition obtained by bioelectric impedancemetry in case of obese women of peri- menopausal age. Method and Materials: 154 obese women were classified according to their degree of obesity according to WHO criteria. The analysis of body composition was performed by impedancemetry. Pearson’s (r) and Spearman’s (r2 ) correlations were calculated to check the relationships between age, weight, BMI, as well as total and segmental body fat composition. Results: 154 women of mean age 40.20 ± 13.13 years, obese, mean BMI 38.66 ± 6.56 Kg/m2 participated in our study. Impedance reduced an average total fat mass% (TFM%) of 45.39 ± 5.67%. BMI is strongly correlated with TFM% (r = 0.73; r2 = 0.82; p ≥ 0.05). For obesity stages 1-2, weight is correlated with BMI (r-r2 > 0.40; p ≤ 0.001). Likewise, a strong correlation exists between weight and TFM in Kg (r2 = 0.82; p ≥ 0.05). For a BMI ≥ 35 Kg/m2 , weight is inversely correlated with age [r2 ≥ (-0.36); p ≤ 0.003]. The FM of the trunk (Kg) is correlated with the weight for obesity grade 3 (r = 0.49; p = 0.0002) and whatever the stage of obesity at the BMI (r ≥ 0.32; p ≤ 0.02). Conclusion: The use of bioelectrical impedancemetry in the diagnostic management of obese people is quite useful. This tool gives us better information on the location and distribution of fatty tissue.
Polluted water poses significant health risks when it is part of the water sources used for irrigation, leading to the contamination of soil and plants by various pollutants. This work aims, firstly, to assess the degree of pollution of Wadi El Gourzi water (Batna, Algeria), and then to verify the consequences on their use for the irrigation of market garden plants for everyday consumption (lettuce, cilantro, parsley and spinach), both in the aerial part (stems and leaves) and in the soil where they are grown. This study focuses on trace metals (Cr, Pb, Zn and Cd). Soil pollution was assessed by calculating the soil pollution index (PI), while the uptake of these elements by plants was monitored by the transfer factor (TF). The analyses of the Wadi El Gourzi water with the flame atomic absorption spectrophotometer (FAAS) show a maximum abnormal concentration of Cr (17.37 mg∙dm–3), Pb (0.71 mg∙dm–3) and Cd (0.45 mg∙dm–3). For the analysis of the soils irrigated by these waters, the results of the PI show that the soils used for the cultivation of parsley and lettuce are polluted by several metals (PI > 1). The concentrations of trace metals elements (TMEs) in the sampled plants show a significant accumulation of Zn, Cd, Pb and Cr by the vegetables (coriander, parsley, spinach and lettuce). These concentrations are above the permitted standards.
In this paper a H∞ control technique addresses the voltage regulation in distributed generation (DG) system connected to power converter under harmonic disturbances. The DG control technique combines a discrete sliding mode control (DSMC) in the current control and a Robust Servomechanism Problem (RSP) in the voltage control. Besides, a fractional Order Proportional-Integral-Derivative (FOPID) controller synthesized with an automatic calibration of adjustable fractional weights is formulated in this work. For performance and high robustness requirements, the parameters of FOPID are optimized through solving a multiobjective optimization problematic based on the automatic calibration of the weighted-mixed sensitivity problem. Furthermore, for ensuring an adequate calibration of parameters, the Integral of Time Weighted Absolute Error (ITAE) criterion with Genetic Algorithm (GA) are used to achieve better voltage regulation. The simulation results show that it can achieve trade-off between nominal performance (NP) and robust stability (RS) margins for the constrained uncertain plants in the large range frequencies. Also, the results validate the effectiveness of the proposed control at which both low total harmonic distortion (THD) and low tracking error.
The main function of a pavement is to distribute the traffic-induced load over its different layers. While the flexible pavement design methods are based on a linear elastic calculation, the real behavior of the different layers is highly nonlinear and elastic. They can also, in some cases, be plastic and viscous. This research aims to develop a three-dimensional numerical model that is closely similar to the test FWTT conditions. The model will have a real geometry wheel footprint (rather than a rectangular shape). As a substitute for incremental loading, the wheel movement during its passage over the specimen will be simulated by a horizontal displacement. These important characteristics of the model represent the novelty and the major difference between the current research and previous studies. The current model, which is based on the finite elements method, uses Abaqus software and a viscoelastic constitutive model. The materials’ viscoelastic properties have been described by the Prony series, also called the relaxation modulus, which is a function of time. This parameter can be defined in most computer-aided engineering (CAE) software. The procedure for calculating the Prony series from experimental data is explained. The results obtained agree with the stress signal amplitude, the stress rotation principal, and the total displacement rotation when the load approaches the node considered and located in the middle of the specimen.
The ongoing pandemic of COVID-19 is causing more health, economic and social issues worldwide. As of July 5, 2021, the world registered more than 184 million cases across 222 countries; more than 4 million have died from the deadly infection. The SARSCoV-2 continues spreading globally; new variants emerge randomly due to errors in the virus' gRNAs replication process. The present paper treats the new delta variant of concern, also known as B.1.617.2 lineage. The study highlights transmissibility, vaccine effectiveness, pathogenicity, and the likelihood of hospital admission related to delta variant infection based on a literature review of 10 indexed databases. The findings indicate high transmissibility of the B.1.617.2 lineage, approving it to be the dominant strain worldwide. Also, reduced vaccine effectiveness is confirmed. However, approved vaccines for emergency use remain valuable against COVID-19's delta variant. Finally, the risk of hospitalization seems to be twice in the case of delta variant infection. A combined approach of vaccination and nonpharmaceutical interventions is the leading way to contain the ongoing pandemic of COVID-19
Wireless sensor networks (WSNs) have become an important component in the Internet of things (IoT) field. In WSNs, multi-channel protocols have been developed to overcome some limitations related to the throughput and delivery rate which have become necessary for many IoT applications that require sufficient bandwidth to transmit a large amount of data. However, the requirement of frequent negotiation for channel assignment in distributed multi-channel protocols incurs an extra-large communication overhead which results in a reduction of the network lifetime. To deal with this requirement in an energy-efficient way is a challenging task. Hence, the Reinforcement Learning (RL) approach for channel assignment is used to overcome this problem. Nevertheless, the use of the RL approach requires a number of iterations to obtain the best solution which in turn creates a communication overhead and time-wasting. In this paper, a Self-schedule based Cooperative multi-agent Reinforcement Learning for Channel Assignment (SCRL CA) approach is proposed to improve the network lifetime and performance. The proposal addresses both regular traffic scheduling and assignment of the available orthogonal channels in an energy-efficient way. We solve the cooperation between the RL agents problem by using the self-schedule method to accelerate the RL iterations, reduce the communication overhead and balance the energy consumption in the route selection process. Therefore, two algorithms are proposed, the first one is for the Static channel assignment (SSCRL CA) while the second one is for the Dynamic channel assignment (DSCRL CA). The results of extensive simulation experiments show the effectiveness of our approach in improving the network lifetime and performance through the two algorithms.
This paper presents the second-order sliding mode controller (SOSMC) of a micro-positioning stage piezoelectric model actuator (PEA), where the C-H model parameters are adopted to describe the hysteresis behavior and identified through particle swarm optimization. In this technique, two control algorithms are developed. The first one is the so-called twisting algorithm (TA). The control appears explicitly in the second surface derivative, and in a discontinuous control action that ensures a sliding regime mode. The second one, the super twisting algorithms (STA) has been developed and analyzed for systems. The use of both algorithms gives a significant reduction in chattering as compared to the standard sliding mode control. It is shown that the STA case offers better performances than TA. Simulation results are presented to demonstrate the advantage of SOSMC over SMC.
The security is so important for both storing and transmitting the digital data, the choice of parameters is critical for a security system, that is, a weak parameter will make the scheme very vulnerable to attacks, for example the use of supersingular curves or anomalous curves leads to weaknesses in elliptic curve cryptosystems, for RSA cryptosystem there are some attacks for low public exponent or small private exponent. In certain circumstances the secret sharing scheme is required to decentralize the risk. In the context of the security of secret sharing schemes, it is known that for the scheme of Shamir, an unqualified set of shares cannot leak any information about the secret. This paper aims to show that the well-known Shamir’s secret sharing is not always perfect and that the uniform randomization before sharing is insufficient to obtain a secure scheme. The second purpose of this paper is to give an explicit construction of weak polynomials for which the Shamir’s (k, n) threshold scheme is insecure in the sense that there exist a fewer than k shares which can reconstruct the secret. Particular attention is given to the scheme whose threshold is less than or equal to 6. It also showed that for certain threshold k, the secret can be calculated by a pair of shares with the probability of 1/2. Finally, in order to address the mentioned vulnerabilities, several classes of polynomials should be avoided.
