A predictive hybrid force modeling in turning: application to stainless steel dry machining with a coated groove tool

The International Journal of Advanced Manufacturing Technology - This paper presents an hybrid numerical/analytical modeling for estimation of cutting forces in machining process. The approach...     

Sintering behavior of magnesium aluminate spinel MgAl2O4 synthesized by different methods

This paper is focusing basically on the ceramic technology, of which several methods for the synthesis of MgAl₂O₄ have been investigated. The synthesis conditions regarding the powders cleanliness, microstructure, and sintering parameters of MgAl₂O₄ were studied. MgAl₂O₄ powder was synthesized via conventional solid-state route using different milling process: vertical attrition milling, WAB as a high-energy horizontal attrition milling, and Pulverisette as a planetary ball miller, and via solution combustion route using Urea, Glycine, and a mixture of Urea/Glycine. Urea and Glycine was used as fuel. The white powders were obtained for all solid-state routes and for Urea-combustion technique. The black and gray powders were obtained in the case of combustion technique, respectively, using a fuel of Glycine and Glycine/Urea mixture. The obtained powders and pellets were characterized by XRD, SEM, and Dilatometry. The results show that, among all the solid-state route processes, wet attrition milling gives the better and clean spinel phase. The WAB milling and Pulverisette miller introduce a contamination by some yttria-stabilized zirconia balls in the corresponding powder. Furthermore, the flash combustion technique permit to have nanoparticles with a dense spinel phase of MgAl₂O₄ and with lower sintering temperature in less time and with no calcination step.     

Effects of friction conditions on the formation of dead metal zone in orthogonal cutting – a finite element study

Abstract

A numerical study of the effects of friction conditions on the formation of dead metal zone (DMZ) is presented. The friction conditions are classified as three different cases in the form of coefficient: (1) constant coefficient of friction, (2) “smooth” and “sharp” change of the friction coefficient and (3) time-dependent friction coefficient. These friction cases are numerically investigated using the finite element (FE) code ABAQUS/Explicit. A FE model based on the arbitrary-Lagrangian–Eulerian approach is developed to simulate the cutting process and investigate the influences of the friction conditions. The simulated results, for a wide range of friction conditions, are obtained, analyzed and compared with previously published experimental/numerical data. It has been found that the friction coefficient has a direct effect on the amount and shape of DMZ, the sharp change of coefficient has a larger effect on the DMZ formation than the smooth one and the formation of DMZ is more determined by the value of the friction coefficient than its duration.     

Behavior Study of the Nanostructured Zn1-xCdxO (0 ≤ x ≤ 0.1) Semiconductor Thin Films Deposited onto Silicon Substrate by Dip-Coating Method

Silicon - The specimens of nanostructured semiconductor of Zn1-xCdxO (0 ≤ x ≤ 0.1) thin films were grown on silicon substrate using a dip-coating method. The...     

Influence of Low Cd-Doping Concentration (0.5 and 3 wt.%) and Different Substrate Types (Glass and Silicon) on the Properties of Dip-Coated Nanostructured ZnO Semiconductors Thin Films

Journal of Inorganic and Organometallic Polymers and Materials - The investigation of semiconductor films of undoped ZnO and doped with two weight percentages of Cadmium (0.5 and 3) were grown on...     

Quality assurance of voice over WLANs (VoWLANs) with differentiated services

Several technical issues make commercial and large voice over wireless local area network (VoWLAN) services difficult to provide. The most challenging issue when voice over Internet Protocol (VoIP) services are ran over IEEE 802.11-based WLANs is the bandwidth inefficiency due to the considerable overhead associated with WLAN packet transmission. In this work, we propose a session-based quality-of-service management architecture (SQoSMA) to overcome the low number of VoIP calls in IEEE 802.11 Wireless LANs and the negative effect of new call addition when the WLAN reaches its capacity. The SQoSMA combines data and control planes to detect VoWLAN QoS degradations and performs either an adaptive audio codec switching or a call stopping to fix VoWLAN issues in a differentiated services manner. In addition, our solution deals with user sessions information, by considering user priority (from its agreement) to guarantee a certain level of its multimedia applications. Performance evaluation using a real test-bed shows that call codec change and call stopping techniques can easily assure high-priority calls with acceptable call blocking probability.     

Towards efficient distributed service discovery in low-power and lossy networks

Low-power and Lossy Networks (LLNs) have been recognised as a promising technology to achieve ubiquity in the internet of things era. To realise this, service oriented architectures and the emerging IPv6 over low-power wireless personal area network (6LoWPAN) standard are identified as key paradigms. One of the main elements to succeed any service oriented approach is a proficient service discovery protocol. In this paper, we propose EADP: an efficient protocol to announce and discover services in 6LoWPAN networks. EADP adopts a fully distributed approach using an adaptive push–pull model to ensure fast discovery times, low energy consumption and low generated overhead with timely reaction to network dynamics. EADP achieves this by using context-awareness information, delivered by a trickle algorithm. EADP was implemented and evaluated in Contiki using the Cooja simulator. Simulation results show EADP’s capability to realise fast discovery times with low cost in terms of energy and overhead. These achievements make EADP very suitable for pervasive LLN applications.     

A lightweight efficient chaos‐based cryptosystem for constrained‐node networks

Interconnected sensor and actuator objects creating Constrained‐Node Networks (CNN) are among the most prominent technologies of the Internet of things. Deployed to monitor our lives, surroundings, and critical infrastructure, CNN communications must be strongly secured in order to prevent devastating unauthorized access to critical information. This, however, faces severe challenges imposed by CNN constraints in terms of energy, memory, and computational power. To address such conflicting requirements, this paper presents a chaos‐based efficient lightweight secure communication system for CNNs. The proposed cryptosystem performs optimized confusion‐diffusion operations at the byte level allowing it to be fully implemented on an 8‐bit microcontroller. Obtained results from extensive experiments at both statistical and implementation levels confirm the robustness of the proposed cryptosystem against a multitude of attacks. Additionally, the evaluated encryption/decryption speeds along with the low memory and energy consumption grant the proposed cryptosystem attractive lightweight aspects enabling its deployment in very constrained CNN applications having soft real‐time requirements.