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41.
Fern Sassower Sisser 《Mathematical Programming》1981,20(1):110-121
The problem of minimizing a nonlinear objective function ofn variables, with continuous first and second partial derivatives, subject to nonnegativity constraints or upper and lower bounds on the variables is studied. The advisability of solving such a constrained optimization problem by making a suitable transformation of its variables in order to change the problem into one of unconstrained minimization is considered. A set of conditions which guarantees that every local minimum of the new unconstrained problem also satisfies the first-order necessary (Kuhn—Tucker) conditions for a local minimum of the original constrained problem is developed. It is shown that there are certain conditions under which the transformed objective function will maintain the convexity of the original objective function in a neighborhood of the solution. A modification of the method of transformations which moves away from extraneous stationary points is introduced and conditions under which the method generates a sequence of points which converges to the solution at a superlinear rate are given. 相似文献
42.
43.
Julian I Palmore 《Journal of Differential Equations》1981,40(2):279-290
We prove the existence of many homographic solutions of the n-body problem in E4 by topological methods. Homographic solutions are associated with relative equilibria. Homothetic solutions always give rise to central configurations. In Euclidean space E4 central configurations are a proper subset of the relative equilibria for any n ? 3 and for any (mi)?R+n. We compare the existence and classification of homographic solutions of the n-body problem in E3 with the Newtonian potential and that of homographic solutions of the n-body problem in E4. Classifying relative equilibria leads to classifying homographic solutions. 相似文献
44.
Ferric ferrocyanides synthesized from different sources of ferric cations and ferrocyanide anions and those derived from ferrous ferricyanide, ferrous ferrocyanide and ferric ferricyanide have been studied using Mössbauer and XRD techniques. Structural information of the effect of the provenance on the properties of the final compound is obtained. Significant correlations between isomer shift and quadrupole splitting of inner and outer iron cations have been observed. 相似文献
45.
Ultrasonic analysis of edible fats and oils 总被引:7,自引:0,他引:7
Low intensity ultrasound is a powerful analytical technique for investigating the physico-chemical properties of many biological and non-biological materials. In this article its application for the characterization of edible fats and oils is assessed. Ultrasound can be used to determine the dynamic rheology and composition of oils, the oil content and droplet size of emulsions and the solid fat content of partially crystalline emulsions. It is capable of rapid and precise measurements, is non-destructive and non-invasive, can be used on-line or off-line and is relatively inexpensive. Ultrasonic techniques will therefore prove a useful addition to the existing analytical techniques used to characterize fats and oils. 相似文献
46.
Francesco Carlà Giulio Campo Claudio Sangregorio Andrea Caneschi César de Julián Fernández Lourdes I. Cabrera 《Journal of nanoparticle research》2013,15(8):1-16
Quantum dots (QDs) have received considerable attention due to their unique optical and electrical properties. Although substantial research has focused on the potential applications and toxicological impacts of QDs, far less effort has been directed toward understanding their fate and transport in the environment. In this work, the effect of four coatings, polyethylene glycol functionalized polymer (PEGP), carboxyl derivatized polymer (COOHP), linoleic acid (LA), and polyacrylic acid-octylamine (PAA-OA), on the transport and retention of QDs in porous media were evaluated under environmentally relevant conditions. Aqueous QD suspensions (ca. 10 nM) were introduced into water-saturated columns packed with 40–50 mesh Ottawa sand at a pore-water velocity of 7.6 m/day. At an ionic strength (IS) of 3 mM and pH of 7, PEGP-coated QDs were completely retained within the column, while more than 60 % of COOHP-coated QDs were transported through a column run under identical conditions. When PAA-OA and LA were used as coatings, effluent QD recoveries increased to more than 65 and 89 % of the injected mass, respectively. Additionally, a decrease in pH from 9.5 to 5.0, or an increase of IS from 0 to 30 mM reduced the eluted mass of PAA-OA-coated QDs by more than 2 and 15 times, respectively. The relative mobility of coated QDs (LA > PAA-OA > COOHP > PEGP) was consistent with total interaction energy profiles between QDs and sand surfaces calculated based on Derjaguin–Landau–Verwey–Overbeek (DLVO) theory. At an IS of 3 mM (NaCl) and pH 7, a linear correlation was obtained between the fraction of eluted QDs and the magnitude of the primary interaction energy barrier. These findings demonstrate the strong dependence of QD transport on coating type and indicate that interaction energies based on DLVO theory can be used to predict the relative mobility of QDs in porous media. 相似文献
47.
48.
Acoustic classification of multiple simultaneous bird species: a multi-instance multi-label approach 总被引:1,自引:0,他引:1
Briggs F Lakshminarayanan B Neal L Fern XZ Raich R Hadley SJ Hadley AS Betts MG 《The Journal of the Acoustical Society of America》2012,131(6):4640-4650
Although field-collected recordings typically contain multiple simultaneously vocalizing birds of different species, acoustic species classification in this setting has received little study so far. This work formulates the problem of classifying the set of species present in an audio recording using the multi-instance multi-label (MIML) framework for machine learning, and proposes a MIML bag generator for audio, i.e., an algorithm which transforms an input audio signal into a bag-of-instances representation suitable for use with MIML classifiers. The proposed representation uses a 2D time-frequency segmentation of the audio signal, which can separate bird sounds that overlap in time. Experiments using audio data containing 13 species collected with unattended omnidirectional microphones in the H. J. Andrews Experimental Forest demonstrate that the proposed methods achieve high accuracy (96.1% true positives/negatives). Automated detection of bird species occurrence using MIML has many potential applications, particularly in long-term monitoring of remote sites, species distribution modeling, and conservation planning. 相似文献
49.
Alberto Castellón Serrano Antonio Fernández López Amable García Martín Cándido Martín González 《manuscripta mathematica》1996,90(1):479-487
In this paper, we use the known classification of the finite capacity simple alternative pairs and the version of the Litoff
Theorem for Jordan pairs to describe all the strongly prime alternative pairs with nonzero socle. We study the inheritance
of some properties (primeness, nondegenerancy,…) when passing from the original alternative pair to the symmetrized pair.
Thus, we can apply Jordan theoretical results to the alternative case.
This work has been partially supported by 1) the “Plan Andaluz de Investigación y Desarrollo Tecnológico” with project no.
1027 and 2) the DGICYT with project no. PB93-0990 相似文献
50.
H. Auer J. Fernández-Niello H. Puchta F. Riess 《Zeitschrift für Physik A Hadrons and Nuclei》1984,318(3):323-327
Theγ-rays following the radioactive decay of160Lu into160Yb have been studied. The Lu source was produced in the144Sm(19F, 3n) reaction at 85 MeV. Excitation functions, half-lives,γ-γ andγ-X-ray coincidences and conversion electrons were measured. Twoβ + decaying states in160Lu were found with half-lives of 36.2(3) s and 40(1) s.160Yb levels deduced from the decay of160Lu are presented. 相似文献