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排序方式: 共有496条查询结果,搜索用时 15 毫秒
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S. Angelis A. C. Novak E. B. Sydney V. T. Soccol J. C. Carvalho A. Pandey M. D. Noseda J. L. Tholozan J. Lorquin C. R. Soccol 《Applied biochemistry and biotechnology》2012,167(5):1092-1106
In this study, the biomass and exopolysaccharides (EPS) production in co-cultures of microalgae/cyanobacteria and macromycetes was evaluated as a technology for producing new polysaccharides for medical and/or industrial application. Based on biomass and EPS productivity of monocultures, two algae and two fungi were selected and cultured in different co-culture arrangements. The hydrosoluble EPS fractions from mono- and co-cultures were characterized by 13C NMR spectroscopy and gas chromatography coupled to mass spectrometry and compared. It was found that co-cultures resulted in the production of an EPS different from those produced by monocultures, showing fungal predominance with microalgal/cyanobacterial traces. Co-cultures conditions were screened (temperature, agitation speed, fungal and microalgae inoculation rate, initial pH, illumination rate, and glucose concentration) in order to achieve maximum biomass and EPS production, resulting in an increase of 33 and 61% in exopolysaccharides and biomass productions, respectively (patent pending). 相似文献
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Feichtinger Gustav Andreas J. Novak 《Mathematical and Computer Modelling of Dynamical Systems: Methods, Tools and Applications in Engineering and Related Sciences》2013,19(3):197-211
In this paper we present a simple time-continuous behavioural model of habit formation. Addictive behaviour is damped by a threshold which adapts itself to the habit. This adaptive behaviour of the threshold may lead to periodic fluctuations of the consumption rate, the habit and the threshold. It turns out that both a low adjustment rate of the threshold as well as a steep consumption function favour oscillatory patterns. 相似文献
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The management of technology in multi-service computer networks, such as university networks, has become a challenge with the explosive growth of entertainment oriented peer-to-peer (P2P) traffic. Traffic shaping is one of the tools used to manage bandwidth to improve system performance by allocating bandwidth between P2P and non-peer-to-peer (NP2P) traffic. We present a model for traffic shaping and bandwidth management that considers the trade-offs from allocating different amounts of bandwidths for different application categories and use data from a university network. The current policy allocates varying bandwidths over the day to P2P and NP2P traffic to reflect the importance of not letting entertainment based traffic choke the network during the day time at the expense of the more important traffic, such as Web traffic. We highlight the difficulties in obtaining data in the form required for analysis, and the need to estimate demand for allocations not covered by current policy. We present a goal programming model for this estimation task. We also model the traffic shaping problem as a Markov decision process and develop an algorithm for determining the optimal bandwidth allocation to maximize the utility of all users. Finally we use a numerical example to illustrate our approach. 相似文献
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I. I. Novak G. A. Oganesyan 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2007,1(3):294-297
The formation process of electrically active oxygen-containing complexes (thermal donors) in silicon is investigated at the initial stage of thermal treatment at T < 500°C under elastic tensile stress σ = 1 GPa. It is shown that, under these conditions, the formation of singly charged donor centers is observed in silicon when the oxygen concentration is (3–5) × 1017 cm?3. When the oxygen concentration is 9 × 1017 cm?3, doubly charged donor centers form. The depth profile of thermal donors is found in the samples studied. 相似文献
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Erich Novak 《Aequationes Mathematicae》1991,41(1):161-167
Summary We study the average case behavior of suitable algorithms to solve a nonlinear problem in numerical analysis: determining zeroes of increasing Lipschitz functions of one variable. The bisection method (which is optimal with respect to the maximal error over the whole class of functions) is far from being optimal in a more general sense: There are methods which behave like bisection in the worst case but which yield much better results on the average. We prove that the sequentially optimal algorithm found by Sukharev is also optimal in our average case setting. 相似文献