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In this work, Cu 2 O/CuO composite films were obtained by annealing, in free air, Cu thin films. These latter were deposited on glass substrates by Glancing Angle Deposition “GLAD” technique at a fixed glancing angle α, measured from the substrate normal. Nanorods tilted toward the incident deposition direction are produced with stationary substrate. Cu GLAD films were deposited under various angles α (0–80°). Structural and optical properties of obtained films were investigated based on XRD, Raman and UV–vis absorption data. The dependence of these properties on annealing temperature and deposition angle was analyzed. The obtained XRD patterns and Raman spectra revealed Cu 2 O, CuO and metallic Cu phases in films annealed at 200 °C, while a CuO monophase was obtained after annealing at 300 °C. Microstructural parameters, such as crystallite size, strain and dislocation density were calculated using Williamson–Hall model. Stacking fault probability was determined using Warren–Warekois relation. Band gap and Urbach energies, as well as other optical parameters were estimated from optical absorption data. The obtained results are in good agreement with the literature. [ABSTRACT FROM AUTHOR]

Abstract: In x Ga1−x As/GaAs pseudomorphic structures were grown by metalorganic vapor phase epitaxy. Reciprocal space mapping were recorded in the vicinity of (004) and (115) nodes using high resolution X-ray diffraction (HRXRD) in order to determine strain tensor components, indium compositions and thicknesses of alloys. Near-infrared photoluminescence (PL) was performed at 10K. The impact of strain on PL response was revealed by peak energy positions and line width. In addition, valence-band splitting (VBS) and the shift of the heavy-hole were measured. Besides, photoreflectance (PR) at room temperature was useful to establish experimentally the dependence of VBS and band energy shifts (E 0 and E 0+∆ 0) on elastic strain due to lattice mismatches. Other parameters such as the internal electric-field and the electro-optical energy were determined from Franz–Keldysh oscillations analysis. Good correlation between the results obtained from all investigated techniques and theoretical predictions was confirmed. [Copyright &y& Elsevier]

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In process planning, trajectory planning has generally disregarded the limitations of the feed drive systems in terms of acceleration, jerk, and motion blending. It results in poor prediction of the feed rate mainly in the transient phases and affects, consequently, the machining integrity and safety. Therefore, identifying and integrating the feed drive system limitations with the trajectory planning of the tool path are crucial in order to achieve the desired feed rate at the appropriate tool position. In this paper, a methodology based on time series modeling is proposed to identify the acceleration/deceleration (Acc/Dec) profile of a feed drive system. This profile provides the relationship between the actual feed rate, assumed proportional to the tachometer signal, and the commanded feed rate specified in the G-Code file. A particular shape of the input has been addressed to allow the application of the time series modeling. The different characteristics of this input are carefully considered to avoid both nonlinear response due to saturation and excitation of the high frequency components of the feed drive. The resulting model is transformed into a Finite Impulse Response (FIR) filter and applied as an (Acc/Dec) processor to determine the actual feed rate from the commanded feed rate. The good agreement between the model output and the experimental results demonstrates the effectiveness of the proposed identification method. It is demonstrated that integrating these limitations with the trajectory planing results in a feasible trajectory. [Copyright &y& Elsevier]

The optimized feed scheduling strategy, developed in part I of this paper, considers an optimal use of the feed drive systems. The low frequency dynamics of the different feed drive systems of the machine tool are identified. The resulting transfer functions are transformed into FIR filter and integrated with the planning of the tool trajectory. The effectiveness of the proposed feed scheduling strategy is demonstrated using ball end milling of a workpiece that provides variable cutting conditions along a nonlinear tool path. The performance of this strategy in terms of productivity, machining safety, and machining accuracy, is compared to a feed scheduling strategy based on control points. The proposed strategy has significantly improved the tracking and trajectory following characteristics. It achieves a good prediction of the feed rate of the different axes and consequently a better regulation of the cutting force. In addition, by increasing the feed rate, while respecting the different constraints, it improves the tool path accuracy and enhances the productivity. [Copyright &y& Elsevier]

An optimized feed scheduling strategy is proposed in this paper to maximize the metal removal rate in 3-axis machining while guaranteeing the machining accuracy. The tool path is assumed defined by a cubic parametric form. In part I of this paper, the fundamentals of this strategy are presented. This strategy integrates the feed drive dynamics, described by the acceleration/deceleration (Acc/Dec) profile, with the minimum-time trajectory planning in order to achieve the desired feed rate at the appropriate position. An optimum use of the feed drive capabilities is considered to track the changes in the cutting geometry along the tool path and to ensure an acceptable contour error. Therefore, this strategy combines different constraints and various criteria in modifying the feed rate to maintain a near-constant cutting force resulting in a highly non-linear problem. The constraints include the cutting force magnitude, the feed rate boundaries, the contour error and the characteristics of the (Acc/Dec) profile of the different feed drive systems. The criteria are the maximum production rate, the machining accuracy and safety. In part II of this paper, the effectiveness of this strategy is demonstrated using ball end mill operation on a workpiece that provides variable cutting geometry along a non-linear tool path. The performance of this strategy in terms of productivity, machining safety, and machining accuracy, is compared to a feed scheduling strategy based on control points as well as to milling with constant feed rate. [Copyright &y& Elsevier]

This paper proposes a methodology to identify the material coefficients of constitutive equation within the practical range of stress, strain, strain rate, and temperature encountered in metal cutting. This methodology is based on analytical modeling of the orthogonal cutting process in conjunction with orthogonal cutting experiments. The basic mechanics governing the primary shear zone have been re-evaluated for continuous chip formation process. The stress, strain, strain rate and temperature fields have been theoretically derived leading to the expressions of the effective stress, strain, strain rate, and temperature on the main shear plane. Orthogonal cutting experiments with different cutting conditions provide an evaluation of theses physical quantities. Applying the least-square approximation techniques to the resulting values yields an estimation of the material coefficients of the constitutive equation. This methodology has been applied for different materials. The good agreement between the resulting models and those obtained using the compressive split Hopkinson bar (CSHB), where available, demonstrates the effectiveness of this methodology. [Copyright &y& Elsevier]

L'impact des implantations dentaires provoquent des tissus nécrotiques, mou et osseux, notamment à proximité des métaux à Z élevé. Nous avons cherché à identifier une méthode simple pour réduire la rétrodiffusion liée à l'existence des prothèses dentaires métalliques. Une dent naturelle (ρ = 2,2 g/cm3) et des échantillons à Z élevé ont été utilisés (dent en amalgame Hg-Ag : ρ = 12 g/cm3, couronne métallique Ni-Cr : ρ = 8 g/cm3, implant dentaire en titane : ρ=4,5 g/cm3, couronne céramométallique : ρ = 2,4–8 g/cm3). Une chambre plate Markus (TW23343) a été placée au dessus de la surface de chacun de ces echantillons métalliques. Afin de determiner la valeur de la retrodiffusée, la chambre plate parallèle a été inversée de manière à ce qu'elle soit en contact avec ces différents échantillons. Cinq mesures avec un pas de 1 mm ont été effectuées dans un champ (8 × 8) à une distance source–axe de 100 cm, à une profondeur de 2 cm, avec une énergie de 6 MV. Ensuite, une couche de 3 mm de cire a été étalée sur chaque échantillon métallique et la mesure de la nouvelle valeur de rétrodiffusée est déterminée. Les rétrodiffusions des échantillons métalliques mesurées par rapport à une dent naturelle étaient : 13 % pour l'amalgame Hg-Ag, 9 % pour une couronne métallique Ni-Cr, 5 % pour un implant dentaire en titane, 7 % pour une couronne céramométallique. L'utilisation de 3 mm de cire a permis la réduction de la rétrodiffusion de 6 %, 4 % et 3 % respectivement pour l'amalgame, la couronne et l'implant en titane. Notre technique a quantifié la rétrodiffusion résultant de la présence de métaux à Z élevé, ce qui peut être considérablement atténué avec l'application d'au moins de 3 mm de cire. L'utilisation des matériaux non toxiques tels que la cire étalés avec une faible épaisseur sur des alliages à Z élevés doit être considérée au cours de planification du traitement. Des études plus approfondies sont recommandées dans le but de trier des matériaux appropriés pour la protection de la muqueuse buccale même en présence d'implantations dentaires. [ABSTRACT FROM AUTHOR]

Objectif de l’étude L’interaction des rayonnements ionisants avec les structures biologiques diffère selon la densité du milieu traversé. Des travaux antérieurs ont montré qu’il existe une variation de dose au niveau des cavités d’air. L’objectif de ce travail était d’évaluer les perturbations de dose produites à l’interface de deux milieux de densités différentes, pour des rayonnements d’énergies de 6 et 18 MeV d’un accélérateur Clinac-iX et de 1,25 MeV d’une source de cobalt 60. Matériel et méthode Différents volumes en polystyrène de densité assimilable aux cavités d’air au niveau de la tête, du cou et du thorax ont été utilisés. Des films Gafchromic EBT3 ont été employés pour la mesure de la dose. Le calcul de la dose a été effectué en utilisant l’algorithme AAA d’Eclipse de Varian (pour les énergies X6, X18, et 1.25 MeV de cobalt 60) et le logiciel de simulation Primo/Penelope (pour l’énergie X6). Résultats Une variation importante en fonction de la taille de faisceau a été constatée : plus la taille était petite, plus l’écart entre ce qui était mesuré et ce qui était calculé était important. Une variation en fonction de l’énergie a été trouvée : plus l’énergie était importante plus le calcul de dose était en concordance avec la dose mesurée par les films EBT3. Toutefois, pour l’énergie X6, un écart important entre la dose mesurée avec EBT3 et la dose calculée par AAA de l’ordre de 10 % a pu être observé ainsi qu’un écart de 5 % avec la dose calculée par Primo. De même, une variation en fonction de l’épaisseur de la cavité d’air pour des énergies différentes a été notée : pour l’énergie X06 plus l’épaisseur de la cavité était grande plus les doses mesurées s’ajustaient avec les doses calculées par l’algorithme AAA et les doses simulées par Primo. Conclusion Les écarts obtenus entre les valeurs mesurées et les valeurs calculées avec AAA sont en concordance avec des travaux précédents. Tandis que les résultats obtenus pour la simulation effectuée par Primo, montraient des écarts moins importants entre les valeurs calculées et celles mesurées par EBT3. [ABSTRACT FROM AUTHOR]

The challenge of die and mold milling is to achieve the specified dimensional and geometrical accuracy, and improve the surface roughness, in order to minimize polishing operations, still necessary to meet the tight tolerances required by the automotive industry and the plastic injection sector. The present study investigates the multi-axis milling of a specific mold steel grade Super Plast ® 300* (SP300) , by a ball nose carbide tool coated with Ti(CN). Surface finish analysis given by 3D measurements and data processing techniques shows that micro-geometrical defects generated by C1 continuous tool path are definitely less serious than those obtained by classical tool paths driven via linear interpolation. Also, polishing time saving is more than 30%. Thus, a substantial productivity enhancement is achieved in dies and molds manufacturing. [Copyright &y& Elsevier]

Abstract: The present study describes a computer simulation model for refrigerant ejector. A one-dimensional mathematical model was developed using the equations governing the flow and thermodynamics based on the constant-area ejector flow model. The model includes effects of friction at the constant-area mixing chamber. The current model is based on the NIST-REFPROP database for refrigerants’ properties calculations. The simulated performance is compared with the available experimental data from the literature for validation. The effects of operating parameters and environment friendly refrigerants on critical entrainment ratio are studied. [Copyright &y& Elsevier]