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81.
82.
A spherical helical antenna is proposed and its radiation characteristics are analysed using numerical methods and experimental measurements. Results for a 10 turn helix are presented. These results indicate that the spherical helix can provide circular polarisation over a wide beamwidth. The radiation patterns have a broad main beam, essentially no sidelobes, and low backlobe level.<> 相似文献
83.
CL Cardoso CB Muraro VL Siqueira M Guilhermetti 《Canadian Metallurgical Quarterly》1998,36(3):820-823
A comparative study of microscopic examination of 10 microl (simplified loop technique) and 50 microl (traditional drop technique) of uncentrifuged Gram-stained urine specimens for detection of significant bacteriuria was carried out. The results demonstrated that the 10-microl loop technique can be used as an alternative to the 50-microl drop technique for presumptive diagnosis of urinary-tract infection in bacteriological practice, with the advantages of greater rapidity and ease of performance. 相似文献
84.
Thermal stability and flammability studies of coated polymer powders using a plasma fluidized bed process 总被引:1,自引:0,他引:1
A. Quédé J. Cardoso M. Le Bras R. Delobel P. Goudmand O. Dessaux C. Jama 《Journal of Materials Science》2002,37(7):1395-1399
In this work, the thermal stability of organosilicon coatings, polyamide-6 powders and polyamide-6 clay nanocomposite powders coated with organosilicon are studied. The coatings were obtained from polymerization of 1.1.3.3-tetramethyldisiloxane (TMDS) monomer doped with oxygen using a cold remote nitrogen plasma (CRNP) process. A fluidized bed reactor using CRNP assisted polymerization was used to coat the polymer powders. The effect of oxygen addition to TMDS on the thermal stability was investigated. Oxygen addition to TMDS promotes the formation of more thermally stable coated polymers. In the case of the polyamide-6 clay nanocomposite, the Limiting Oxygen Index values were much improved. This shows that the deposits are effective fire retardant coatings. 相似文献
85.
SS de Oliveira J Abrantes M Cardoso D Sordelli MC Bastos 《Canadian Metallurgical Quarterly》1998,27(5):287-291
The inhibitory activity of five bacteriocin (Bac)-producer strains of Staphylococcus aureus was tested against bacteria pathogenic for cattle. Sixty-five epidemiologically unrelated strains of Staph. aureus involved in bovine mastitis were used as indicators in an agar diffusion test. Bacteriocins produced by four strains could inhibit only a limited number of test organisms. However, all 65 indicator strains proved to be susceptible to the combined action of both bacteriocins encoded by pRJ9, a Bac plasmid found in strain A53. Therefore, the bacteriocins produced by this strain may represent new antimicrobial peptides with potential applications in the prevention and treatment of bovine mastitis. 相似文献
86.
Pedro G. Coelho Luís O. Faria Joo B. Cardoso 《International Journal of Machine Tools and Manufacture》2005,45(12-13):1451-1460
A model of the bending process in Press Brakes is established using Timoshenko beam theory. Expressions for the workpiece bending error are derived that explicitly consider the influence of shape, dimensions and initial deformation of the machine structural components on its bending accuracy. The minimization of the bending error is formulated in terms of optimisation problems that are solved numerically using a genetic algorithm. The methodology presented in this paper permits the analysis of existing Press Brake design solutions, the optimisation of their performance and the development of new solutions. 相似文献
87.
Blind signal separation: statistical principles 总被引:41,自引:0,他引:41
Cardoso J.-F. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》1998,86(10):2009-2025
Blind signal separation (BSS) and independent component analysis (ICA) are emerging techniques of array processing and data analysis that aim to recover unobserved signals or “sources” from observed mixtures (typically, the output of an array of sensors), exploiting only the assumption of mutual independence between the signals. The weakness of the assumptions makes it a powerful approach, but it requires us to venture beyond familiar second order statistics, The objectives of this paper are to review some of the approaches that have been developed to address this problem, to illustrate how they stem from basic principles, and to show how they relate to each other 相似文献
88.
J.C. Wang P.S. Cardoso J.A.Q. Gonzalez M. Strum R. Pires 《Journal of Electronic Testing》2004,20(4):333-344
There are several ways to insert Built-in Self-Test (BIST) circuitry on a circuit, each of them with particular consequences on area overhead, test application time and fault coverage. This paper presents a BIST insertion methodology applied to datapaths described at the RTL level that uses a database containing: (a) testability data of several types of test pattern generators (TPGs) and signature analyzers (SAs) when connected to several types of functional units and (b) area overhead due to the implementation by a datapath register of each type of those test resources. The availability of this database makes then possible to choose the best test resource types associated to each functional unit in a datapath, leading to good testability and area results. 相似文献
89.
Joaquim P. Cardoso Martin F. Chaplin A. Nicholas Emery John F. Kennedy Livio P. Revel-Chion 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1978,28(11):775-783
Methods are described for the immobilisation of enzymes on inorganic supports activated by the surface deposition of an imperfectly crystallised film of TiO2. The stability of the preparations is shown to be strongly dependent on the integrity of the support-TiO2 link which is in turn dependent on the pretreatment of the solid support. The enzyme may be linked to the activated support using 5-aminosalicylic acid (with or without diazotisation), tannic acid or stannous chloride, or by direct contact. These preparations are shown to have activities and operational stabilities superior to those of a preparation made using the silane-glutaraldehyde method on the same glass support. 相似文献
90.
L. G. Sousa J. B. Cardoso A. J. Valido 《Structural and Multidisciplinary Optimization》1997,13(2-3):112-118
This paper shows an optimal design problem with continuum variational formulation, applied to nonlinear elasticplastic structures subject to dynamic loading. The total Lagrangian procedure is used to describe the response of the structure. The direct differentiation method is used to obtain the sensitivities of the structural response that are needed to solve the optimization problem. Since unloading and reloading of the structure are allowed, the structural response is path-dependent and an additional step is needed to integrate the constitutive equations. It can be shown, consequently, that design sensitivity analysis is also path-dependent. A finite element method with implicit time integration is used to discretize the state and sensitivity equations.A mathematical programming approach is used for the optimization process. Numerical applications are performed on a 3-D truss structure, where cross-sectional areas and nodal point coordinates are treated as design variables. Optimal designs have been obtained and compared by using two different strategies: a twolevel strategy where the levels are defined according to the type of design variables, cross sectional areas or node coordinates, and optimizing simultaneously with respect to both types of design variables. Comparisons have also been made between optimal designs obtained by considering or not considering the inertial term of the structural equilibrium. 相似文献