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121.
Andr L. Maravilha Eduardo G. Carrano Felipe Campelo 《International Transactions in Operational Research》2020,27(1):418-434
This work introduces a heuristic for mixed integer programming (MIP) problems with binary variables, based on information obtained from differences between feasible solutions as well as solutions from the linear relaxation. This information is used to build a neighborhood that is explored as a sub‐MIP problem. The proposed heuristic is evaluated using 45 problems from the MIPLIB repository. Its performance, in terms of solution improvement over the results obtained after exploring 50,000 nodes of the branch‐and‐bound tree, is compared against that of Solution Polishing, which is another recombination‐based heuristic for MIP problems used within the CPLEX solver; as well as against the solution obtained by running the default CPLEX branch‐and‐cut (B&C) method under a same time limit. The computational results indicate that the proposed method is able to yield results that are significantly better than those obtained by the default CPLEX B&C approach and comparable to those of Solution Polishing in terms of the mean solution quality. This equivalence of expected solution quality, coupled with a simpler implementation, suggests the use of the proposed approach as a possible alternative for improving the quality of solutions in MIP problems. 相似文献
122.
Camila Soares Henrique Fontenele Garcia Maria do Rosário Maurício Ribeiro Macário Ezequiel Dantas de Araújo Girão Menezes Carlos Felipe Grangeiro Loureiro 《Networks and Spatial Economics》2018,18(2):415-439
Accessibility planning with reference to sustainability and equity principles has been advocated as the best approach to deal with the urban mobility complexity. It has enabled the development of more sustainable and fair policies in relation to access provision. However, despite this paradigm shift, many planning initiatives in practice are still focused on assessing alternatives and proposing solutions, instead of centering on the understanding and assessment of problems as the primary activity of planning. Therefore, in order to contribute for the problem-oriented paradigm in the accessibility planning, this work proposes a strategic assessment methodology for unequal and inequitable distribution problems of accessibility and mobility. This methodology relies on spatial analysis techniques and allows the characterization of accessibility and mobility conditions, as well as the diagnosis of accessibility and mobility problems and their causal relationships. It was applied for the case of Lisbon and the results of the performed assessment allowed an intelligent reading of the problems considered. Specifically, it was found that Lisbon presents an unequal and inequitable distribution of job accessibility and mobility by private car and public transport, and also that job accessibility, along with other transportation, land-use and socioeconomic variables, impact the mobility levels of its citizens. 相似文献
123.
The use of composite indicators to evaluate the performance of Brazilian hydropower plants 下载免费PDF全文
Felipe A. Calabria Ana S. Camanho Andreia Zanella 《International Transactions in Operational Research》2018,25(4):1323-1343
This paper investigates the performance of the largest Brazilian hydropower plants. This study covers 78% of the total installed capacity from hydros in the country, and considers indicators reflecting operational and maintenance costs as well as quality of service. The assessment was conducted using a new approach for the construction of composite indicators, based on a directional distance function model. First, we assessed the hydropower plants allowing for complete flexibility in the definition of weights, enabling the identification of underperforming plants, and quantification of their potential for improvement. Next, we assessed the plants considering different perspectives regarding the importance attributed to each indicator. This allowed reflecting different points of view, focusing primarily on operation and maintenance costs or quality issues. The results identify the hydropower plants that can be considered benchmarks in different scenarios, and allow testing the robustness of plants' classification as benchmarks in the unrestricted model. 相似文献
124.
Affonso Felipe Dias Thiago Magela Rodrigues Pinto Adilson Luiz 《Mobile Networks and Applications》2021,26(1):256-265
Mobile Networks and Applications - Predicting the stock market is a widely studied field, either due to the curiosity in finding an explanation for the behavior of financial assets or for financial... 相似文献
125.
Ignacio Moreno‐Villoslada Felipe Oyarzún Víctor Miranda Susan Hess Bernab L. Rivas 《应用聚合物科学杂志》2005,98(2):598-602
The binding of cationic chlorpheniramine maleate (CPM) to the anionic water‐soluble polymers (WSPs) alginic acid, carboxymethylcellulose, κ‐carageenan, and ι‐carageenan was evaluated by diafiltration at pH 7.5 and in the absence and presence of 0.13M NaCl. CPM interacted with all of the WSPs when no NaCl was present in the solution, with charge‐related formation constants of around 700 M?1 for all of the polymers, whereas the interactions were cleaved in the presence of 0.13M NaCl, indicating interactions of an electrostatic nature screened by the single electrolyte. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 598–602, 2005 相似文献
126.
Felipe Silva Jardel Silveira Jarbas Silveira César Marcon Fabian Vargas Otávio LimaJr 《Journal of Electronic Testing》2018,34(4):417-433
As the microelectronics technology continuously advances to deep submicron scales, the occurrence of Multiple Cell Upset (MCU) induced by radiation in memory devices becomes more likely to happen. The implementation of a robust Error Correction Code (ECC) is a suitable solution. However, the more complex an ECC, the more delay, area usage and energy consumption. An ECC with an appropriate balance between error coverage and computational cost is essential for applications where fault tolerance is heavily needed, and the energy resources are scarce. This paper describes the conception, implementation, and evaluation of Column-Line-Code (CLC), a novel algorithm for the detection and correction of MCU in memory devices, which combines extended Hamming code and parity bits. Besides, this paper evaluates the variation of the 2D CLC schemes and proposes an additional operation to correct more MCU patterns called extended mode. We compared the implementation cost, reliability level, detection/correction rate and the mean time to failure among the CLC versions and other correction codes, proving the CLCs have high MCU correction efficacy with reduced area, power and delay costs. 相似文献
127.
The obtaining of materials incorporating multiple metal elements is of interest because the combination of various metal cations results in the achievement of new and enhanced properties. Metal-organic frameworks (MOFs) offer a suitable platform to combine multiple metal elements due to their modular nature and highly controllable structure. The incorporation of various metal elements into MOFs might be accomplished by following different synthetic approaches, which in turn determine the way in which the various metal elements are arranged in the framework. In this contribution, we will overview the formation of multi-metal MOFs by the introduction of new metal sites in the organic linkers, or in the inorganic secondary building units through cation exchange process, or one-pot synthesis. 相似文献
128.
CFD as an approach to understand flammable dust 20 L standard test: Effect of the ignition time on the fluid flow 下载免费PDF全文
Daniel Vizcaya Andrés Pinilla Mariangel Amín Nicolás Ratkovich Felipe Munoz Carlos Murillo Nathalie Bardin‐Monnier Olivier Dufaud 《American Institute of Chemical Engineers》2018,64(1):42-54
A computational study based on the Euler–Lagrange approach was developed for the characterization of flammable dusts in the 20 L sphere standard test. The aim of the study was to analyze some parameters that might affect the experimental data (e.g., cold turbulence and particle size). The turbulence of a wheat starch cloud was described with the Detached Eddy Simulation model. Both the pressure of the system and the RMS velocity were compared with the flow patterns established with a particle image velocimetry analysis. It was concluded that the rebound nozzle forms a cloud that is composed by clumps. This fact implies dissimilarities between the local concentrations and the nominal value. Finally, a granulometric analysis established that the mean diameter of the particle size distribution (PSD) decreased by 69% during the dispersion. Thus, it is suggested to consider the PSD at the ignition zone rather than the PSD of the sample. © 2017 American Institute of Chemical Engineers AIChE J, 63: 42–54, 2018 相似文献
129.
Jesus E. Molinar-Solis Felipe Gomez-Castaneda Jose A. Moreno-Cadenas Victor H. Ponce-Ponce 《The Journal of VLSI Signal Processing》2007,49(1):207-216
At present, the Cellular Neural Network (CNN) is a potential parallel structure able to perform image processing tasks in
real-time when is effectively implemented in CMOS technology. The CNN silicon integration success is due mainly to the local
connectivity of processing cells. In this work, an alternative design based on floating-gate MOS inverters is presented, which
uses unipolar signals for solving binary tasks. The approach brings a fast response in a reduced silicon area, as shown through
electrical simulations. A prototype cell in CMOS technology (AMI, 1.2 micron) was fabricated and tested for eight image processing
tasks.
相似文献
Victor H. Ponce-Ponce |
130.
Cervantes FG Heinzel G Marín AF Wand V Steier F Jennrich O Danzmann K 《Applied optics》2007,46(21):4541-4548
We present a real-time differential phase-front detector sensitive to better than 3 mrad rms, which corresponds to a precision of approximately 500 pm. This detector performs a spatially resolving measurement of the phase front of a heterodyne interferometer, with heterodyne frequencies up to approximately 10 kHz. This instrument was developed as part of the research for the Laser Interferometer Space Antenna Technology Package interferometer and will assist in the manufacture of its flight model. Because of the advantages this instrument offers, it also has general applications in optical metrology. 相似文献