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41.
We study the marginal impact of customer flexibility in service systems. We consider a queueing system with multiple parallel servers, in which a proportion of customers are flexible and can go to any server, while the remainder require service at a particular server. We show that the stationary expected waiting time is decreasing and convex in the proportion of flexible customers. We also show, for a related Inventory Model, in which servers are never idle and can build up inventory, that convexity holds in a strong sample-path sense. Our results reinforce the idea that a little flexibility goes a long way. 相似文献
42.
Baljinder K. Kandola S. Ilker Mistik Wiwat Pornwannachai A. Richard Horrocks 《Molecules (Basel, Switzerland)》2021,26(15)
Biocomposites comprising a combination of natural fibres and bio-based polymers are good alternatives to those produced from synthetic components in terms of sustainability and environmental issues. However, it is well known that water or aqueous chemical solutions affect natural polymers/fibres more than the respective synthetic components. In this study the effects of water, salt water, acidic and alkali solutions ageing on water uptake, mechanical properties and flammability of natural fibre-reinforced polypropylene (PP) and poly(lactic acid) (PLA) composites were compared. Jute, sisal and wool fibre- reinforced PP and PLA composites were prepared using a novel, patented nonwoven technology followed by the hot press method. The prepared composites were aged in water and chemical solutions for up to 3 week periods. Water absorption, flexural properties and the thermal and flammability performances of the composites were investigated before and after ageing each process. The effect of post-ageing drying on the retention of mechanical and flammability properties has also been studied. A linear relationship between irreversible flexural modulus reduction and water adsorption/desorption was observed. The aqueous chemical solutions caused further but minor effects in terms of moisture sorption and flexural modulus changes. PLA composites were affected more than the respective PP composites, because of their hydrolytic sensitivity. From thermal analytical results, these changes in PP composites could be attributed to ageing effects on fibres, whereas in PLA composite changes related to both those of fibres present and of the polymer. Ageing however, had no adverse effect on the flammability of the composites. 相似文献
43.
Hudlicky T Rinner U Gonzalez D Akgun H Schilling S Siengalewicz P Martinot TA Pettit GR 《The Journal of organic chemistry》2002,67(25):8726-8743
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We study the existence of local analytic first integrals of a class of analytic differential systems in the plane, obtained from the Chua?s system studied in L.O. Chua (1992, 1995), N.V. Kuznetsov et al. (2011), G.A. Leonov et al. (2012) , , and . The method used can be applied to other analytic differential systems. 相似文献
47.
The proposed decision model, based on Analytic Network Process (ANP), has been developed in order to determine the dynamics
of the Global System for Mobile Communications (GSM) market. In accordance with the sequence of ANP, first of all, the problem
was structured and modeled. At the next step, a quantitative analysis was conducted with the customers in order to assess
the importance of the related factors and forecast the market shares of the Turkish mobile communication operators. The forecasted
market share values were compared with actual ones for the validation of the decision model. The assessed importance of the
factors in a valid model would be a potential competitive advantage for the mobile operators. 相似文献
48.
Biswas A Bayer IS Biris AS Wang T Dervishi E Faupel F 《Advances in colloid and interface science》2012,170(1-2):2-27
This review highlights the most significant advances of the nanofabrication techniques reported over the past decade with a particular focus on the approaches tailored towards the fabrication of functional nano-devices. The review is divided into two sections: top-down and bottom-up nanofabrication. Under the classification of top-down, special attention is given to technical reports that demonstrate multi-directional patterning capabilities less than or equal to 100 nm. These include recent advances in lithographic techniques, such as optical, electron beam, soft, nanoimprint, scanning probe, and block copolymer lithography. Bottom-up nanofabrication techniques--such as, atomic layer deposition, sol-gel nanofabrication, molecular self-assembly, vapor-phase deposition and DNA-scaffolding for nanoelectronics--are also discussed. Specifically, we describe advances in the fabrication of functional nanocomposites and graphene using chemical and physical vapor deposition. Our aim is to provide a comprehensive platform for prominent nanofabrication tools and techniques in order to facilitate the development of new or hybrid nanofabrication techniques leading to novel and efficient functional nanostructured devices. 相似文献
49.
Betul Akkopru Akgun Nathan P. Mellott Caner Durucan 《Journal of Sol-Gel Science and Technology》2012,62(2):240-251
Silver containing silica (Ag–SiO2) thin films with and without aluminum (Al) were prepared on soda-lime-silica glass by spin coating of aqueous sols. The coating
sol was formed through mixing tetraethyl orthosilicate [Si(OC2H5)4]/ethanol solution with aqueous silver nitrate (AgNO3) and aluminum nitrate nonahydrate [(AlNO3)3·9H2O] solutions. The deposited films were calcined in air at 100, 300 and 500 °C for 2 h and characterized using x-ray diffraction,
UV-visible and x-ray photoelectron spectroscopy. The effect of Al incorporation and calcination treatment on microstructure
and durability of the films, and chemical/physical state of silver in the silica thin film have been reported. The bactericidal
activity of the films was also determined against Staphylococcus aureus via disk diffusion assay studies before and after chemical durability tests. The investigations revealed that the optical,
bactericidal properties and chemical durability of Ag–SiO2 films can be improved by Al addition. The Al-modified Ag–SiO2 thin films do not exhibit any coloring after calcination in the range of 100–500 °C, illustrating that silver is incorporated
within the silica gel network in ionic form (Ag+). Al incorporation also improved the overall durability and antibacterial endurance of Ag–SiO2 thin films. 相似文献
50.
Akgun Z Engelbrecht H Fan KH Barnes CL Cutler CS Jurisson SS Lever SZ 《Dalton transactions (Cambridge, England : 2003)》2010,39(42):10169-10178
(103)Rhodium(III) complexes derived from seven acyclic tetradentate N(2)S(2) ligands (one diaminedithiol and six diaminedithioether ligands) have been synthesized and characterized. Structural variations in the ligand include the length of carbon backbone between the coordinating atoms (222; 232; 323; 333), the presence or absence of gem-dimethyl groups α to sulfur, and the nature of the organic moiety on the sulfurs (hydrogen, p-methoxybenzyl and methyl). For each ligand, the formation of cis and/or trans dichloro isomeric complexes was assessed. Two complexes have been further characterized by single crystal X-ray diffraction. Preparation of the (103)Rhodium(III) complexes was conducted and overall radiochemical yields, in vitro stability and log D(7.4) values were measured. From these studies, the ligand with the 232 chain length, gem-dimethyl groups and the methyl thioether (L4) emerged as a preferred ligand for formation of rhodium complexes with trans geometry and highest radiochemical yields. 相似文献