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排序方式: 共有97条查询结果,搜索用时 15 毫秒
1.
G. Severino E. J. Paiva J. R. Ferreira P. P. Balestrassi A. P. Paiva 《The International Journal of Advanced Manufacturing Technology》2012,63(5-8):523-534
The machining process for vertical turning martensitic gray cast iron is of great importance to the automotive industry, mainly in the manufacturing process of piston rings. The aim of this paper is to demonstrate the process of development of coated carbide tools to maximize the productivity of the process, considering the maximum life of the cutting tool and the minimum machining cost per part. Using full-factorial design of experiments, we tested two different geometries: a square tool with special geometry—formed by two edges and two ends simultaneously cutting—and a hexagonal tool. Considering that the special square geometry provided maximum life, full quadratic models for responses of interest were constructed using a central composite design for feed (f) and rotation (n). Applying the generalized reduced gradient algorithm, the proposed optimization goals were achieved with feed f?=?0.37?mm/v and rotation of 264?rpm for the use of the special square tool. Confirmation experiments prove the effectiveness of this solution. 相似文献
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3.
Matteo Ottavian Pierantonio Facco Massimiliano Barolo Paolo Berzaghi Severino Segato Enrico Novelli Stefania Balzan 《Journal of food engineering》2012
This study investigated the possibility of using near-infrared spectroscopy (NIRS) for the authentication of Asiago d’allevo, a protected designation of origin cheese from northern Italy. Latent variable models applied on spectral data were developed and used to estimate several chemical properties and to classify the available dataset according to the location and management of the cheesemaking factory (lowland and alpine), the ripening age (6, 12, 18 and 36 months), the altitude of milk production (low, medium, medium–high and high), and the period of the year of the cheese production (May, July and September). The variable importance in projection index was used to identify the most informative spectral regions for discrimination. Results showed that NIR spectra can be used both to accurately estimate several chemical properties and to classify the samples according to the different experimental conditions under investigation with the same discrimination capacity provided by traditional chemical analysis. 相似文献
4.
A. Severino C. Frewin C. Bongiorno R. Anzalone S.E. Saddow F. La Via 《Diamond and Related Materials》2009,18(12):1440-1449
Growth of 3C-SiC on (100) Si has been performed via chemical vapor deposition under two pressure regimes (low and atmospheric pressure) in the early stage of growth. Atomic force microscopy (AFM) and transmission electron microscopy (TEM) have been conducted to study the initial stage of growth while X-ray diffractometry (XRD) and TEM have been used to analyze thicker films and to detect and quantify defects, resulting in a comprehensive and detailed investigation of 3C-SiC structural defects. We have found out that the secondary nucleation of 3C-SiC island growth leads to a higher defect generation rate and, at the same time, to a more effective defect elimination rate. Hillocks found on the surface of thin samples grown under reduced pressure conditions are more pronounced as they seem to be a consequence of twins created in the early stage of growth. Finally, a different initial nucleation density (in the two pressure regimes considered) does not strongly influence stacking fault and microtwin density when growth of thick 3C-SiC films is performed. A very strong influence is indeed observed when 3C-SiC thickness is limited to hundreds of nanometers. 相似文献
5.
Mary C.F. Alves Severino J.G. Lima José W.M. Espinosa Luiz E.B. Soledade Iêda M.G. Santos 《Materials Letters》2009,63(1):118-120
Strontium stannate (SrSnO3), a perovskite material, was synthesized by the polymeric precursor method, with different routes to eliminate organic matter. The utilization of pure oxygen for the elimination of organic matter changed the Raman spectra, especially in the low frequency region. Some peaks, which were previously assigned to the perovskite phase, were not noticed when the carbonate amount was lower. On the other hand, the profile of the IR spectra and XRD patterns did not change. These results suggest that carbonate may be present inside the perovskite lattice. 相似文献
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7.
Jorge Laine Joaquin Brito Francisco Severino Germán Castro Patricia Tacconi Simón Yunes José Cruz 《Catalysis Letters》1990,5(1):45-54
The effect of prereduction on CO oxidation activity of unsupported copper-chromite oxide catalysts was examined. Results were found to be in good agreement with two mechanisms for a surface copper enrichment due to CO prereduction which produced an activity increase in the copper-chromite catalyst. 相似文献
8.
Felipe C. da Silva Carolina Rodrigues da Fonseca Severino Matias de Alencar Marcelo Thomazini Julio C. de Carvalho Balieiro Paola Pittia Carmen Sílvia Favaro-Trindade 《Food and Bioproducts Processing》2013,91(1):28-36
The aim of this work was to obtain propolis in a powder, alcohol-free, water-dispersed and shelf-stable form. Propolis extract was spray-dried using gum Arabic and octenyl succinic anhydride (OSA) starch as carriers in two different weight ratios (1:4 and 1:6). Spray-dried propolis samples were evaluated for morphology, moisture, water activity, water dispersibility, hygroscopicity, particle size, particle distribution, entrapping efficiency, stability, isotherms and antioxidant properties. The spray-drying process produced round particles with sizes ranging from 15 to 24 μm. This process preserved the antioxidant activity of propolis and also allowed propolis to be obtained in a powder form, which was stable during storage at room temperature, had low hygroscopicity and was highly dispersible in cold water. The application of this technology could increase the use of propolis in various industrial applications, such as an antimicrobial and as an antioxidant in food. 相似文献
9.
Joanna Kulesza Bráulio Silva Barros Severino Alves Júnior Carlos Alberto Fernandes de Oliveira Dulce Maria de Araújo Melo Jaroslaw Chojnacki 《Materials Chemistry and Physics》2014
Hydro(solvo)thermal reactions of Cu(NO3)2·2.5H2O or Zn(NO3)2·6H2O with 1,3-H2bdc provided two structurally different coordination polymers; a 2D network “metallacalixarene” based on the paddlewheel-type cluster with the formula [Cu(1,3-bdc)·H2O]·H2O (1) and a 3D framework [Zn(1,3-bdc)] (2), respectively. The use of a base was unnecessary in this synthesis; however, the presence of benzene played a crucial role in the crystallization of the desired products and could act as a template molecule in the synthesis of polymer (1). The unsaturated apical sites in the Cu2 cluster of polymer (1) were occupied by water molecules, what consequently led to the structural decomposition of the framework after exposing the sample in air, which was not the case of the Zn-coordination polymer (2). 相似文献
10.
J. Laine F. Severino R. Golding 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1984,34(7):387-393
A series of trimetallic (NiCoMo) hydrodesulphurisation supported catalysts were prepared using a successive impregnation method, varying the ratio of promoters Ni/(Ni + Co) and maintaining the ratio (Ni + Co)/Mo constant. Optima for higher thiophene hydrodesulphurisation activity were found for ratios Ni/(Ni + Co) of 0.7 and 0.8. It is suggested that the optima may be strongly dependent on method of catalyst preparation, and/or type of support employed. Presulphidation was found to increase the activity in NiMo more than in CoMo. Testing of commercial catalysts confirmed various differences between CoMo and NiMo catalysts. 相似文献