The market demand for machining and cutting of various plastics parts is in continuous increase. The aim of this study is to extract prediction laws for surface roughness, cutting forces and temperatures evolution during the machining of two polyethylene pipes grades (HDPE-100) and (HDPE-80). It was found that feed rate is the most prevailing factor on roughness criteria and that better surfaces are obtained during the machining of the harder HDPE-80 resin. Also, cutting speed improved surface quality for speeds up to 200 m.min −1 but the rising interface temperature caused surface damage and material rapid softening. Also, feed exponents, in mathematical models, were found to be 3 to 4 times higher than those of cutting speed and depth of cut. An increase in the cutting speed led to a gradual reduction for the 3 cutting forces components (Fr, Fa and Fv ) with a dominance of the tangential force (Fv ). As expected, the value of the depth of cut had a large influence on the temperature within the cutting zone. This temperature is slightly higher during the machining of HDPE-80 compared to that of HDPE-100 most probably because of hardness differences. The analysis of variance (ANOVA) was performed to check the adequacy of the mathematical models relating cutting parameters with roughness, cutting forces and global cutting zone temperature.

The demand for the machining and cutting of plastic parts is in continuous increase. The present study is intended to investigate the optimization of high density polyethylene (HDPE-100) orthogonal turning operation using the Grey Relational Analysis (GRA). Accordingly, experimental tests based on Taguchi method are performed to establish a correlation between cutting parameters on one hand and machining force, specific cutting force and roughness of machined surface on the other hand. An optimal parameters combination for the turning process is obtained. In addition to regression models deduction, the analysis of variance (ANOVA) is applied to identify the most significant factors. It is found that the order of the importance of controllable factors to the tangential cutting force (Ft) is feed rate (f), depth of cut (ap) and cutting speed (Vc). However, when considering the importance with respect to specific cutting force (Ks), the order becomes (Vc), (ap) and (f). Finally, the order of cutting parameters according to mean roughness criteria, represented by (Ra), (Rz) and (Rt), shifts to (f), (Vc) and (ap). The optimized cutting regime ensuring minimization of roughness and cutting forces is well described by Vc = 188 m/min, f = 0.14 mm/rev and ap = 3 mm. This study unveiled new approaches based on combined GRA and ANOVA for machining other polymers such as tough reinforced polymers and composites used as human prosthesis.

In this study, turning operations on polyamide PA66 with cemented carbide insert, were organized according to the L27 Taguchi design whose objective is the analysis of the cutting parameters on the output parameters (Surface roughness and cutting force), as well as on the calculated parameter (material removal rate (Q)). The results revealed that surface roughness is highly impacted by the feed rate, which accounts for more than 68% of the variance, followed by the cutting speed and finally the depth of cut. With respect to cutting force, depth of cut and feed rate have emerged as the most important terms.A mathematical model is then created to predict the surface roughness and cutting force. Finally, the optimal cutting regime leading to good surface quality with less cutting force and maximum productivity was examinedusing two multi criteria optimization methods namely PCA and PCA coupled with TOPSIS. The total desirability function was used as a decision criterion for evaluating the two optimization methods. The results demonstrate the potential superiority of the PCA-TOPSIS method over the PCA method.

Wireless body area networks (WBANs) is now a well-accepted technology that provides not only efficient and remote health-care services but also targets the integration of future multimedia applications, in which high data rate is compulsory. UWB communication is one of the key solutions that afford such rates, and its extended version, multiband OFDM (MB-OFDM) has recently shown its efficiency with WBANs. However, increasing the data rates may come at the expense of the data reliability which is a critical issue in biomedical applications. Cooperative diversity has proven its ability in offering such robustness to channel errors while avoiding to use multiple antennas. Indeed, a single antenna terminal is sufficient to achieve diversity benefits by sharing its physical resources with cooperating single antenna relays. Aiming at providing a viable compromise between the data rate and accuracy in low-profile UWB body networks, to incorporate a decodeand-forward-based cooperative architecture in MB-OFDM system by resorting to opportunistic relaying approach is proposed, which retains only the best on-body relay to forward the information to the destination, thereby significantly reducing the complexity.

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This paper focuses on a comparative study of the machinability of two semi-crystalline polymers (POM-C) and (PA-6), during dry turning operations. The aim is to experimentally examine the impact of cutting parameters, namely cutting speed, feed, and depth of cut on surface roughness, cutting force, cutting power, and material removal rate. A series of experiments according to a Taguchi L18 plan was implemented. The ANOVA analysis revealed that the type of material a substantial effect on surface roughness, followed by feed, whereas cutting force and cutting power are more affected by depth of cut. Linear regression models with interactions proved effective in predicting the studied responses, and single-objective optimization using SA and GA methods were applied to optimize each response. The GRA and COPRAS methods coupled with weighting methods CRITIC, ROC, SWARA, and Entropy are used for multi-objective optimization of the considered responses. The results showed that the combination of the COPRAS method with the SWARA method provides a better compromise, which is of crucial interest for researchers in the field of optimization in polymer material machining.

Prolonging the lifetime of wireless sensor networks (WSN) is the biggest challenging issue. In wireless multimedia sensor networks (WMSNs), sensor nodes have limited energy resource and to increase the lifetime of the network, it is necessary to design an effective fast algorithm that aims at reducing the consumed power. This paper proposes an energy-efficient discrete cosine transform (DCT) approximation requiring only 12 additions. Associated with a JPEG compression chain, this DCT approximation ensures a very good rate-distortion compromise, but above all, a very low computational complexity and significant compatibility with the exact DCT. Simulation results clearly show that the proposed fast transform algorithm achieves a better trade-off between image quality, computational complexity and energy consumption compared to any existing pruned DCT approximations. Furthermore, it is very suitable for the resource constrained wireless visual sensor networks (WVSNs) requiring low bitrates.