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991.
Ant colony optimisation is a constructive metaheuristic in which solutions are built probabilistically influenced by the parameters of a pheromone model—an analogue of the trail pheromones used by real ants when foraging for food. Recent studies have uncovered the presence of biases in the solution construction process, the existence and nature of which depend on the characteristics of the problem being solved. The presence of these solution construction biases induces biases in the pheromone model used, so selecting an appropriate model is highly important. The first part of this paper presents new findings bridging biases due to construction with biases in pheromone models. Novel approaches to the prediction of this bias are developed and used with the knapsack and generalised assignment problems. The second part of the paper deals with the selection of appropriate pheromone models when detailed knowledge of their biases is not available. Pheromone models may be derived either from characteristics of the way solutions are represented by the algorithm or characteristics of the solutions represented, which are often quite different. Recently it has been suggested that the latter is more appropriate. The relative performance of a number of alternative pheromone models for six well-known combinatorial optimisation problems is examined to test this hypothesis. Results suggest that, in general, modelling characteristics of solutions (rather than their representations) does lead to the best performance in ACO algorithms. Consequently, this principle may be used to guide the selection of appropriate pheromone models in problems to which ACO has not yet been applied. 相似文献
992.
Marcus J. Smith Qingji Zeng Evan Lafalce Shengtao Yu Shuaidi Zhang Zeev Valy Vardeny Vladimir V. Tsukruk 《Advanced functional materials》2019,29(30)
This study reports a facile method for the assembly of large, array style, coupled dye‐doped microsphere resonators by template‐assisted, in which an aqueous suspension of colloidal microspheres assemble on a patterned template. By exploiting the high resolution of 3D (two‐photon) lithography derived templates, closely packed large arrays, hundreds to thousands of dimers with controlled gap spacing, only limited by the size of the substrate can be achieved. Dye‐doped emissive microspheres with Q‐factors >2.5 × 102 can be achieved and trapped into predetermined cavity positions, thereby controlling the distance between adjacent microspheres. This design allows to scale down dimer spacing from usual 400 nm for traditional photolithography to very small spacing of 50 nm. It is found that exciting individual microspheres in the ensemble shows intense optical cavity modes, whereas closely coupled pairs show controlled mode splitting. Coupling between photoluminescent microspheres is strongly influenced by the gap distance, with strong coupling, equating to normal mode splitting, arising as the gap distance is reduced below traditional sub‐micrometer scale. The coupled dimer assemblies are promising candidates for advancing the development of large‐area coupled nanophotonic structures, beyond the spatial resolution‐limited photolithographical derived arrays. 相似文献
993.
994.
Fajer Mushtaq Xiangzhong Chen Harun Torlakcik Christian Steuer Marcus Hoop Erdem Can Siringil Xavi Marti Gregory Limburg Patrick Stipp Bradley J. Nelson Salvador Pan 《Advanced materials (Deerfield Beach, Fla.)》2019,31(28)
Here, the catalytic degradation of organic compounds is reported by exploiting the magnetoelectric nature of cobalt ferrite–bismuth ferrite (CFO–BFO) core–shell nanoparticles. The combination of magnetostrictive CFO with multiferroic BFO gives rise to a magnetoelectric engine that purifies water under wireless magnetic fields via advanced oxidation processes, without involvement of any sacrificial molecules or cocatalysts. Magnetostrictive CoFe2O4 nanoparticles are fabricated using hydrothermal synthesis, followed by sol–gel synthesis to create the multiferroic BiFeO3 shell. Theoretical modeling is performed to study the magnetic‐field‐induced polarization on the surface of magnetoelectric nanoparticles. The results obtained from these simulations are consistent with experimental findings of the piezoforce microscopy analysis, where changes in piezoresponse of the nanoparticles under magnetic fields are observed. Next, the magnetoelectric‐effect‐induced catalytic degradation of organic pollutants is investigated under AC magnetic fields, and 97% removal efficiency for synthetic dyes and over 85% removal efficiency for routinely used pharmaceuticals are obtained. Additionally, trapping experiments are performed to elucidate the mechanism behind the magnetic‐field‐induced catalytic degradation of organic pollutants by using scavengers for each of the reactive species. The results indicate that hydroxyl and superoxide radicals are the main reactive species in the magnetoelectrically induced catalytic degradation of organic compounds. 相似文献
995.
Cicely Shillingford Brandon M. Kim Marcus Weck 《Small (Weinheim an der Bergstrasse, Germany)》2020,16(16)
Capillary assembly is a versatile method for depositing colloidal particles within templates, resulting in nano/microarrays and colloidal superstructures for optical, plasmonic, and sensory applications. Liquid particles (LPs), comprised of oligomerized 3‐(trimethoxysilyl)propyl methacrylate, are herein shown to deposit into patterned cavities via capillary assembly. In contrast to solid colloids, LPs coalesce upon solvent evaporation and assume the geometry of the template. Incorporating small molecules such as dyes followed by LP solidification generates fluorescent polymer microarrays of any geometry. The LP size is inversely proportional to the quantity of deposited material and the convexity of the final polymer array. Cavity filling can be tuned by increasing the assembly temperature. Extraction of the polymerized regions produces solidified particles with faceted shapes including square prisms, trapezoids, and ellipsoids with sizes up to 14 µm that retain the shape of the cavity in which they are initially held. LP deposition thus presents a highly controllable fabrication scheme for geometrically diverse polymer microarrays and anisotropic colloids of any conceivable polygonal shape due to space filling of the template. The extension of capillary assembly to LPs that can be doped with small molecule dyes and analytes invaluably expands the synthetic toolbox for top‐down, scalable, hierarchically engineered materials. 相似文献
996.
Gabriele Bavota Andrea De Lucia Andrian Marcus Rocco Oliveto 《Empirical Software Engineering》2013,18(5):901-932
Changes during software evolution and poor design decisions often lead to packages that are hard to understand and maintain, because they usually group together classes with unrelated responsibilities. One way to improve such packages is to decompose them into smaller, more cohesive packages. The difficulty lies in the fact that most definitions and interpretations of cohesion are rather vague and the multitude of measures proposed by researchers usually capture only one aspect of cohesion. We propose a new technique for automatic re-modularization of packages, which uses structural and semantic measures to decompose a package into smaller, more cohesive ones. The paper presents the new approach as well as an empirical study, which evaluates the decompositions proposed by the new technique. The results of the evaluation indicate that the decomposed packages have better cohesion without a deterioration of coupling and the re-modularizations proposed by the tool are also meaningful from a functional point of view. 相似文献
997.
998.
Weighted minimal hypersurface reconstruction 总被引:1,自引:0,他引:1
Goldlücke B Ihrke I Linz C Magnor M 《IEEE transactions on pattern analysis and machine intelligence》2007,29(7):1194-1208
Many problems in computer vision can be formulated as a minimization problem for an energy functional. If this functional is given as an integral of a scalar-valued weight function over an unknown hypersurface, then the sought-after minimal surface can be determined as a solution of the functional's Euler-Lagrange equation. This paper deals with a general class of weight functions that may depend on surface point coordinates as well as surface orientation. We derive the Euler-Lagrange equation in arbitrary dimensional space without the need for any surface parameterization, generalizing existing proofs. Our work opens up the possibility of solving problems involving minimal hypersurfaces in a dimension higher than three, which were previously impossible to solve in practice. We also introduce two applications of our new framework: We show how to reconstruct temporally coherent geometry from multiple video streams, and we use the same framework for the volumetric reconstruction of refractive and transparent natural phenomena, bodies of flowing water. 相似文献
999.
Mukundan Devadas Oliver Krcher Martin Elsener Alexander Wokaun Nicola Sger Marcus Pfeifer Yvonne Demel Lothar Mussmann 《Applied catalysis. B, Environmental》2006,67(3-4):187-196
The influence of NO2 on the selective catalytic reduction (SCR) of NO with ammonia was studied over Fe-ZSM5 coated on cordierite monolith. NO2 in the feed drastically enhanced the NOx removal efficiency (DeNOx) up to 600 °C, whereas the promoting effect was most pronounced at the low temperature end. The maximum activity was found for NO2/NOx = 50%, which is explained by the stoichiometry of the actual SCR reaction over Fe-ZSM5, requiring a NH3:NO:NO2 ratio of 2:1:1. In this context, it is a special feature of Fe-ZSM5 to keep this activity level almost up to NO2/NOx = 100%. The addition of NO2 to the feed gas was always accompanied by the production of N2O at lower and intermediate temperatures. The absence of N2O at the high temperature end is explained by the N2O decomposition and N2O-SCR reaction. Water and oxygen influence the SCR reaction indirectly. Oxygen enhances the oxidation of NO to NO2 and water suppresses the oxidation of NO to NO2, which is an essential preceding step of the actual SCR reaction for NO2/NOx < 50%. DRIFT spectra of the catalyst under different pre-treatment and operating conditions suggest a common intermediate, from which the main product N2 is formed with NO and the side-product N2O by reaction with gas phase NO2. 相似文献
1000.
Peter?S.?Piispanen Marcus?Persson Per?Claesson Torbj?rn?NorinEmail author 《Journal of surfactants and detergents》2004,7(2):161-167
Several novel and some previously known, mostly sugar-based, surfactants have been synthesized, and their surface properties
have been characterized and compared with commercial nonylphenol ethoxylates. The dispersion properties of the surfactants
were studied by mixing carbon black into an aqueous surfactant solution. It was found that open sugars, as the headgroup,
give rise to higher conformational repulsion and hence more effective dispersion properties than ringclosed sugar headgroups
(e.g., furanoside or pyranoside forms). No conclusions could be made about the differences in dispersion properties between
surfactants with aliphatic or aromatic tail groups. Increasing the area of the tail group, however, by using twin-chain tail
groups increased the dispersion properties of the surfactants further. The surfactants’ ability for wetting a hydrophobic
parafilm surface was studied. The sugar-based surfactants were found generally to possess poor wetting properties. 相似文献