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251.
R.S. de Camargo G. Miranda Jr. R.P.M. Ferreira H.P. Luna 《Computers & Operations Research》2009,36(12):3097
The multiple allocation hub-and-spoke network design under hub congestion problem is addressed in this paper. A non-linear mixed integer programming formulation is proposed, modeling the congestion as a convex cost function. A generalized Benders decomposition algorithm has been deployed and has successfully solved standard data set instances up to 81 nodes. The proposed algorithm has also outperformed a commercial leading edge non-linear integer programming package. The main contribution of this work is to establish a compromise between the transportation cost savings induced by the economies of scale exploitation and the costs associated with the congestion effects. 相似文献
252.
“Castelo Branco” cheese is a Portuguese DOP cheese made from raw ewe’s milk coagulated with Cynara cardunculus, ripened for at least 40 days. “Merino da Beira Baixa” pure race is frequently used to produce milk for this cheese, however, exotic races such as Assaf and crusade of these two races are also used. The aim of this work has been to compare the volatile profile and sensory characteristics of DOP “Castelo Branco” cheeses manufactured during winter season with milk of breeds from Merino, Assaf and crusade of these two races and identify volatile compounds that can distinguish these cheeses. 相似文献
253.
Composition and behaviour of cerium films on galvanised steel 总被引:9,自引:0,他引:9
The composition and corrosion performance of galvanised steel treated by immersion in cerium nitrate solution was investigated by electrochemical techniques and surface analysis. The surface film consists of a mixture of Ce(III) and Ce(IV) compounds, being very rich in Ce(III) in the first instants of the deposition process and becoming gradually enriched in the more oxidised form, Ce(IV). The presence of this film on the surface hinders the corrosion reaction by reducing the rate of both the cathodic and the anodic reactions. The film becomes thicker but more uneven when the time of film growth increases, with the development of defects in the film, which in contact with electrolyte behaves anodic with respect to the covered areas of the surface. These thicker films have revealed lower resistance to corrosion initiation. 相似文献
254.
255.
Electrokinetic desalination of glazed ceramic tiles 总被引:1,自引:0,他引:1
Lisbeth M. Ottosen Célia M. D. Ferreira Iben V. Christensen 《Journal of Applied Electrochemistry》2010,40(6):1161-1171
Electrokinetic desalination is a method where an applied electric DC field is the driving force for removal of salts from
porous building materials. In the present paper, the method is tested in laboratory scale for desalination of single ceramic
tiles. In a model system, where a tile was contaminated with NaCl during submersion and subsequently desalinated by the method,
the desalination was completed in that the high and problematic initial Cl− concentration was reduced to an unproblematic concentration. Further conductivity measurements showed a very low conductivity
in the tile after treatment, indicating that supply of ions from the poultice at the electrodes into the tile was limited.
Electroosmotic transport of water was seen when low ionic content was reached. Experiments were also conducted with XVIII-century
tiles, which had been removed from Palacio Centeno (Lisbon) during renovation due to damage of the glazing from the presence
of salts. These tiles were severely contaminated with both chlorides and nitrates, and one of the tiles also contained sulphates
though at a low concentration. The charge transfer was too low in the experiments to obtain full desalination, but promising
results were obtained as significant decreases (>81% Cl−, ~59% NO3
− and ~22% SO4
2−) were seen. 相似文献
256.
The production of polyaniline films on aluminium alloy 6061-T6 in sulphuric acid was carried out by electrodeposition, using cyclic voltammetry and potentiostatic polarization. The films obtained were characterized by SEM and XPS analysis. Electrochemical techniques were also used to assess the anticorrosive properties of the coatings.The choice of the upper potential limits for potential cycling and of the fixed potential for potentiostatic production should take in consideration the balance between their effect on the minimum number of cycles (or time) needed to produce the film and on the rate of overoxidation.Polarization curves show a slight increase of the corrosion potential for polyaniline coated substrate as compared with bare metal, indicating that no significant protection is achieved by the polymer coating. The Bode diagrams show low impedance values for the alloy covered with polyaniline when compared with the results obtained for the bare metal. This can be attributed to the conductive character of the polyaniline films. 相似文献
257.
258.
Ana C. Ferreira A.M. Ferraria A.M. Botelho do Rego António P. Gonçalves M. Rosário Correia T. Almeida Gasche Joaquim B. Branco 《Journal of Alloys and Compounds》2010,489(1):316-323
The study of partial oxidation of methane (POM) over bimetallic nickel–lanthanide oxides was undertaken. Binary intermetallic compounds of the type LnNi (Ln = Pr, Gd, Lu) were used as bimetallic nickel–lanthanide oxides precursors and the products (NiO·Pr2NiO4, 2NiO·Gd2O3 and 2NiO·Lu2O3) were characterized by means of X-ray diffraction, X-ray photoelectron spectroscopy, Raman and temperature programmed reduction. The catalytic activity increases when gadolinium or lutetium replaces praseodymium and the selectivity of the bimetallic nickel–lanthanide oxides is clearly different from that of single metal oxides and/or mechanical mixtures.The existence of an unusual synergism effect between the two metal oxide phases (NiO and Ln2O3) that lead to higher conversions of methane and higher selectivities to hydrogen and carbon monoxide correlate also the catalysts stability to deactivation. The activity and selectivity of the gadolinium and lutetium compounds is, under the same conditions, equivalent to that of a platinum commercial catalyst, 5 wt% Pt/Al2O3, which stresses the good catalytic performance of this new type of compounds for the production of H2 and CO (H2/CO = 2). 相似文献
259.
In this text we present the real-time implementation of a Bayesian framework for robotic multisensory perception on a graphics
processing unit (GPU) using the Compute Unified Device Architecture (CUDA). As an additional objective, we intend to show
the benefits of parallel computing for similar problems (i.e. probabilistic grid-based frameworks), and the user-friendly
nature of CUDA as a programming tool. Inspired by the study of biological systems, several Bayesian inference algorithms for
artificial perception have been proposed. Their high computational cost has been a prohibitory factor for real-time implementations.
However in some cases the bottleneck is in the large data structures involved, rather than the Bayesian inference per se.
We will demonstrate that the SIMD (single-instruction, multiple-data) features of GPUs provide a means for taking a complicated
framework of relatively simple and highly parallelisable algorithms operating on large data structures, which might take up
to several minutes of execution with a regular CPU implementation, and arrive at an implementation that executes in the order
of tenths of a second. The implemented multimodal perception module (including stereovision, binaural sensing and inertial
sensing) builds an egocentric representation of occupancy and local motion, the Bayesian Volumetric Map (BVM), based on which
gaze shift decisions are made to perform active exploration and reduce the entropy of the BVM. Experimental results show that
the real-time implementation successfully drives the robotic system to explore areas of the environment mapped with high uncertainty. 相似文献
260.