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51.
Philippe Baptiste Peter Brucker Marek Chrobak Christoph Dürr Svetlana A. Kravchenko Francis Sourd 《Journal of Scheduling》2007,10(2):139-146
We study the problem of preemptive scheduling of n} jobs with given release times on m identical parallel machines. The objective is to minimize the average flow time. In this paper, show that when all jobs have
equal processing times then the problem can be solved in polynomial time using linear programming. Our algorithm can also
be applied to the open-shop problem with release times and unit processing times. For the general case (when processing times
are arbitrary), we show that the problem is unary NP-hard.
P. Baptiste and C. Dürr: Supported by the NSF/CNRS grant 17171 and ANR/Alpage.
P. Brucker: Supported by INTAS Project 00-217 and by DAAD PROCOPE Project D/0427360.
M. Chrobak: Supported by NSF grants CCR-0208856 and INT-0340752.
S. A. Kravchenko: Supported by the Alexander von Humboldt Foundation. 相似文献
52.
Marzhan A. Sadenova Saule A. Abdulina Svetlana A. Tungatarova 《Clean Technologies and Environmental Policy》2016,18(2):449-459
The results of investigation of catalysts based on natural zeolite in comparison with synthetic ZSM-5 zeolite used in reduction of nitrogen oxides and conversion of carbon monoxide are presented. It was found that rearrangement of the crystal structure of natural zeolite begins upon heating it above 500 °C in air. The structure of natural zeolite has been improved by introduction of various modifiers and selection of thermal regime of samples training. It has been shown that developed compositions of press-mass for preparation of carriers for gas purification catalysts in the form of granules and tablets satisfy the requirements on ductility and mechanical strength. The efficiency of synthesized granular and block Cu–Ce, Cu–Ni–Cr, Ti–V, Ti–VW, and TiO2–V2O5 catalysts based on natural and synthetic zeolites was determined in conversion of CO and nitrogen oxides. The results of X-ray structure analysis of clinoptilolite of the Republic of Kazakhstan deposits—Chankanai and Taizhuzgen—are represented in comparison with synthetic ZSM-5 zeolite. The paper also comprises data about their thermal stability, ductility, and strength of compositions on their base. Metals particles morphology and dispersity are studied by the method of electronic microscopy. These particles were used as active components of synthesized catalysts. 相似文献
53.
S. Mintova N. Petkov K. Karaghiosoff T. Bein 《Microporous and mesoporous materials》2001,50(2-3):121-128
Si-MEL molecular sieve is prepared from aged colloidal precursor solutions under hydrothermal treatment (HT) at 90 °C. In situ dynamic light scattering (DLS) investigations of the precursor solutions and the crystalline Si-MEL sols are performed with the original concentrations. Sub-colloidal particles with a mean radius of about 1 nm and colloidal aggregates with a radius of 10 nm are detected in the precursor colloidal solutions after 5 h aging at room temperature. Consumption of the sub-colloidal particles with time and an increase of the colloidal fraction of 10 nm particles after 48 h aging is observed. After heating of the aged precursor solution at 90 °C for 30 h, three particle populations of 1, 10, and 100 nm radius are formed. Complete transformation from amorphous to crystalline colloidal particles is observed after 68 h extended HT of the aged precursor solution. The mean hydrodynamic radius of the crystalline Si-MEL particles is about 100 nm based on the DLS measurements. The size of the MEL crystals was also confirmed with SEM. Additional time-dependent 29Si NMR measurements of the aged precursor colloidal solutions prior to further crystal growth show that the amount of Q0 species (δ=−71.2) decreases, while signals of high intensity in the range between δ=−88.6 and −98.9 indicating the formation of Q36 and Q38 silicon species appear. IR data reveal that with aging of the precursor colloidal solutions at room temperature, an increased ordering of the silica species similar to those found in the final MEL product is observed. 相似文献
54.
55.
Svetlana Nikolić Ljiljana Mojović Marica Rakin Dušanka Pejin Viktor Nedović 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2009,84(4):497-503
BACKGROUND: Bioethanol produced from renewable biomass, such as corn meal, is a biofuel that is both renewable and environmentally friendly. Significant scientific and technological investments will be needed to achieve substitution of conventional fossil fuels with alternative fuels. The ethanol fermentation of enzymatically obtained corn meal hydrolyzates by free and immobilized cells of Saccharomyces cerevisiae var. ellipsoideus yeast in a batch system was studied. The initial glucose and inoculum concentration and the time required for the efficient ethanol production were optimized taking into account parameters such as ethanol concentration, ethanol yield, percentage of the theoretical yield of ethanol and volumetric productivity in both immobilized and free cell systems. RESULTS: The yeast cells were immobilized in Ca–alginate by an electrostatic droplet generation method. An optimal initial inoculum concentration of 2% (v/v) and optimal fermentation time of 38 h for both immobilized and free yeasts were determined. An optimal initial glucose concentration of 150 g L?1 for free system was achieved. At the initial glucose concentration of 176 g L no substrate or product inhibition were achieved with immobilized yeast. CONCLUSION: By immobilization of the yeast into Ca–alginate using the method of electrostatic droplet generation a superior system was realized, which exhibited lower substrate inhibition and higher tolerance to ethanol. The cells of S. cerevisiae var. ellipsoideus yeast entrapped in Ca–alginate showed good physical and chemical stability, and no substrate and product diffusion restrictions were noticed. Copyright © 2008 Society of Chemical Industry 相似文献
56.
Svetlana Nestorović Desimir Marković Ivana Marković 《Journal of Alloys and Compounds》2010,489(2):582-585
This paper reports the results of investigations on the influence of the so called thermal cycling treatment on the anneal hardening effect of the copper-based Cu–10 at.% Zn alloy. The quenched samples were subjected to cold rolling of 20, 40 and 60% in reduction, followed by annealing with and without thermocycling treatment below the recrystallization temperature. Anneal hardening effect was observed in both samples in the temperature range between 180 and 300 °C and was followed by an increase in the hardness and electrical conductivity. These investigations showed that the thermal cycling treatment some increased the intensity of anneal hardening effect. 相似文献
57.
Abstract
The gaseous products of photocatalytic oxidation (PCO) of acrylonitrile on sulphated P25 in concentrations from 10 to 100 ppm at 60 to 130 °C were CO2, HCN and HNCO. This photocatalyst showed disproportionally improved performance at higher temperature and longer retention times. The temperature-programmed oxidation (TPO) after PCO disclosed possible reaction routes. 相似文献58.
The formation and growth of crystal nuclei of zeolite A from clear solutions at room temperature were studied with low-dose, high-resolution transmission electron microscopy in field emission mode and with in situ dynamic light scattering. Single zeolite A crystals nucleated in amorphous gel particles of 40 to 80 nanometers within 3 days at room temperature. The resulting nanoscale single crystals (10 to 30 nanometers) were embedded in the amorphous gel particles. The gel particles were consumed during further crystal growth at room temperature, forming a colloidal suspension of zeolite A nanocrystals of 40 to 80 nanometers. On heating this suspension at 80 degrees C, solution-mediated transport resulted in additional substantial crystal growth. 相似文献
59.
Larisa I. Privalova Boris A. Katsnelson Nadezhda V. Loginova Vladimir B. Gurvich Vladimir Y. Shur Yakov B. Beikin Marina P. Sutunkova Ilzira A. Minigalieva Ekaterina V. Shishkina Svetlana V. Pichugova Ludmila G. Tulakina Svetlana V. Beljayeva 《International journal of molecular sciences》2014,15(11):21538-21553
We used stable water suspensions of copper oxide particles with mean diameter 20 nm and of particles containing copper oxide and element copper with mean diameter 340 nm to assess the pulmonary phagocytosis response of rats to a single intratracheal instillation of these suspensions using optical, transmission electron, and semi-contact atomic force microscopy and biochemical indices measured in the bronchoalveolar lavage fluid. Although both nano and submicron ultrafine particles were adversely bioactive, the former were found to be more toxic for lungs as compared with the latter while evoking more pronounced defense recruitment of alveolar macrophages and especially of neutrophil leukocytes and more active phagocytosis. Based on our results and literature data, we consider both copper solubilization and direct contact with cellular organelles (mainly, mitochondria) of persistent particles internalized by phagocytes as probable mechanisms of their cytotoxicity. 相似文献
60.
Yulia B. Monakhova Sergey A. Astakhov Svetlana P. Mushtakova 《Chemometrics and Intelligent Laboratory Systems》2010,103(2):108-115
We applied two methods of “blind” spectral decomposition (MILCA and SNICA) to quantitative and qualitative analyses of UV absorption spectra of several non-trivial mixture types. Both methods use the concept of statistical independence and aim at the reconstruction of minimally dependent components from a linear mixture. We examined mixtures of major ecotoxicants (aromatic and polyaromatic hydrocarbons), amino acids and complex mixtures of vitamins in a veterinary drug. Both MICLA and SNICA were able to recover concentrations and individual spectra with minimal errors comparable with instrumental noise. In most cases their performance was similar to or better than that of other chemometric methods such as MCR-ALS, SIMPLISMA, RADICAL, JADE and FastICA. These results suggest that the ICA methods used in this study are suitable for real life applications. 相似文献