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121.
A. L. B. Dos Santos M. A. V. Duarte A. M. Abro A. R. Machado 《International Journal of Machine Tools and Manufacture》1999,39(1):325
An optimum experimental design to determine the coefficients of the Extended Taylor's Equation in machining is proposed. The technique is based on the minimisation of the ratio between maximum and minimum singular values of the matrix of sensitivity of the tool life related to the machining parameter variations. This procedure generates the best set of cutting conditions to be used in tool life tests which results in a fast convergence of the coefficients and their confidence intervals. This technique was compared to the commonly used fractional factorial design when face milling AISI 1045 steel with cemented carbide cutting tools. The results showed a considerable reduction in the number of tests required to obtain a reliable equation when the optimum experimental procedure was used when compared to the factorial design. 相似文献
122.
In this work we report a investigation of the plasmon–longitudinal-optical (LO) phonon interaction effects on the intersubband and intrasubband collective excitation energies in a GaAs–AlνGa1?νAs rectangular quantum well wire. We observe a resonant split of the collective excitation energy into two branches, one with energy lower and other with energy higher than the LO-optical phonon energy ?ωLO. Our calculations are performed using a self-consistent field approximation, which includes the local-field correction within the Singwi, Tosi, Land, and Sjolander (STLS) theory at zero temperature and assuming a three-subband model, where only the first subband is occupied by electrons. The potential confining effects on the collective energies were also considered. 相似文献
123.
Jacques P. Sauvé Antão Moura Filipe T. Marques 《Journal of Network and Systems Management》2009,17(4):422-456
A methodology for designing data center infrastructure for Information Technology (IT) services is developed. The main departure
from existing methodologies is that it evaluates and compares alternative designs using business metrics rather than purely
technical metrics. Specifically, the methodology evaluates the business impact (financial loss) imposed by imperfect infrastructure.
The methodology provides the optimal infrastructure that minimizes the sum of provisioning costs and business losses incurred
during failures and performance degradations. Several full numerical example scenarios are provided and results are analyzed.
The use of the method for dynamically provisioning an adaptive infrastructure is briefly discussed. 相似文献
124.
J. M. Machado M. A. Masse F. E. Karasz J. M. Burnett R. F. Kovar M. A. Druy 《Polymer International》1990,22(1):59-64
Two methods have been developed for the preparation of biaxially oriented poly(phenylene vinylene) from its poly(sulfonium salt) precursor. A two-stage stretching process permits non-equibiaxial stretching over a wide range of deformation ratios and a bubble expansion technique allows equibiaxial planar extension. The resulting films were examined using X-ray diffraction prior to chemical doping with SbF5 vapor. Biaxial orientation was shown to exert considerable influence over the attainable electrical conductivity. 相似文献
125.
126.
Y. L. Machado A. A. Dantas Neto J. L. C. Fonseca T. N. C. Dantas 《Journal of the American Oil Chemists' Society》2014,91(7):1139-1145
The PetroOXY method was used to evaluate the kinetics of oxidation of two edible vegetable oils, extracted from moringa and passion fruit. This method, which uses pure oxygen at 700 kPa is effective and fast and our experiments were carried out at temperatures 110–140 °C with BHA antioxidant additive concentration ranging from 0 to 500 ppm. Moringa and passion fruit oils followed first-order kinetics although, in the case of passion fruit oil, mathematical approximations in the first-order kinetic expression resulted in a final equation that could also be interpreted as deriving from zero-order kinetics. The higher stability of moringa oil was characterized by an activation enthalpy ca. 50 % higher than the one related to passion fruit oil. 相似文献
127.
Galvao R.K.H. Yoneyama T. de Araujo F.M.U. Machado R.G. 《Education, IEEE Transactions on》2003,46(1):22-25
A simple technique for obtaining the parameters of a linearized model for a didactic magnetic levitation system is introduced. The proposed procedure only involves basic concepts of dynamic systems and is suitable for use in undergraduate control experiments. The project and validation of a digital lead compensator based on the linearized model are also presented. 相似文献
128.
Multimedia Tools and Applications - A personal collection of photos shows large variability in the depicted items, making difficult a fully automated solution to cope with sensory and semantic... 相似文献
129.
R.D.S.G. Campilho M.F.S.F. de Moura D.A. Ramantani J.J.L. Morais J.J.M.S. Domingues 《International Journal of Adhesion and Adhesives》2009,29(6):678-686
An experimental and numerical study of the tensile behaviour of three-dimensional carbon-epoxy adhesively bonded strap repairs is presented. Experimentally, the failure mode, elastic stiffness and strength were evaluated for different overlap lengths and patch thicknesses. The numerical simulations, performed in ABAQUS®, allowed obtaining the elastic stiffness and the patch debonding load, used to understand the repairs behaviour. The adhesive layer was simulated with cohesive elements including a mixed-mode cohesive damage model with trapezoidal traction-separation laws in pure modes I and II, to account for the ductile behaviour of the adhesive used. These laws were determined by an inverse method, which consists on the estimation of the cohesive parameters with a fitting procedure of the experimental and numerical load–displacement curves of the respective fracture characterization test. The pure mode III cohesive law was equalled to the pure mode II one. This numerical methodology was found adequate to reproduce the experimentally observed behaviour of these repairs. 相似文献
130.
Evaluation of the physical–chemical properties of aqueous solutions of nonionic surfactants based on polyoxides can be performed by different methods. Depending on the technique used, there can be a significant variation in the critical micelle concentration (CMC) found. This is related to the sensitivity of the technique regarding the unimers and micelles present in the solution as well as the structure of the surfactant evaluated. In this work, the CMC values of aqueous solutions of linear and branched poly(ethylene oxide‐polypropylene oxide) (PEO‐PPO) block copolymers were determined by tensiometry, fluorescence, and particle size analysis, using copolymers having adjacent structures (that is, hydrophilic and hydrophobic segments located adjacently in the copolymer) and alternating structures. Tensiometry was used to measure the surface tension as a function of the copolymer concentration in aqueous solution. Fluorescence was used to determine the fluorescence intensity of pyrene to plot the graphs of the I1/I3 and IE/IM relations according to the surfactant concentration. Finally, particle size analysis was used to determine the diffusion coefficient of the particles. The results showed that the fluorescence and particle size techniques provide lower (and mutually concordant) CMC values and can be considered more precise because these methods directly analyze the bulk of the solution. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 相似文献