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21.
22.
A repairable system is a system that can be restored to an operational state after a repair event. The system may experience multiple events over time that are called recurrent events. To model the recurrent event data, the renewal process (RP), the nonhomogenous Poisson process (NHPP), and the trend-renewal process (TRP) are often used. Compared to the RP and NHPP, the TRP is more flexible for modeling, because it includes both RP and NHPP as special cases. However, for a multi-level system (e.g., system, subsystem, and component levels), the original TRP model may not be adequate if the repair is effected by a subsystem replacement and if subsystem-level replacement events affect the rate of occurrence of the component-level replacement events. In this article, we propose a general class of models to describe replacement events in a multi-level repairable system by extending the TRP model. We also develop procedures for parameter estimation and the prediction of future events based on historical data. The proposed model and method are validated by simulation studies and are illustrated by an industrial application. This article has online supplementary materials. 相似文献
23.
Ultralong 20 Milliseconds Charge Separation Lifetime for Photoilluminated Oligophenylenevinylene–Azafullerene Systems 下载免费PDF全文
Georgios Rotas Kati Stranius Nikolai Tkachenko Nikos Tagmatarchis 《Advanced functional materials》2018,28(7)
The synthesis and characterization of oligophenylenevinylene (OPV)–azafullerene (C59N) systems in the form of OPV–C59N donor–acceptor dyad 1 and C59N–OPV–C59N acceptor–donor–acceptor triad 2 is accomplished. Photoinduced electronic interactions between OPV and C59N within 1 and 2 are assessed by UV–vis and photoluminescence. The redox properties of 1 and 2 are investigated, revealing a set of one‐electron oxidation and three one‐electron reduction processes owed to OPV and C59N, respectively. The electrochemical bandgap for 1 and 2 is calculated as 1.44 and 1.53 eV, respectively, and the free energy for the formation of the charge‐separated state for 1 and 2 via the singlet‐excited state of OPV is found negative, proving a thermodynamically favorable the process. Photoexcitation assays are performed in toluene and o‐dichlorobenzene (oDCB) and the reactions are monitored with time‐resolved absorption and emission spectroscopies. Competitive photoinduced energy and electron transfer are identified to occur in both systems, with the former being dominant in 2 . Markedly, the charge‐separated state in oDCB exhibits a much longer lifetime compared to that in toluene, reaching 20 ms for 1 , the highest ever reported value for fullerene‐based materials. These unprecedented results are rationalized by considering conformational phenomena affecting the charge‐separated state. 相似文献
24.
Kati Raju Dang-Hyok Yoon Jai-Yeoul Lee 《Journal of Superconductivity and Novel Magnetism》2014,27(11):2501-2506
The crystal structure and magnetic properties of a typical polycrystalline double-layered manganite, La1.2Sr0.9Ca0.9Mn2O7, were examined using neutron diffraction and magnetization techniques. Neutron diffraction was performed at low and room temperatures and the crystal structure was refined using the Rietveld method based on the space group I4/Mmm. Low temperature neutron diffraction and magnetization measurements clearly revealed antiferromagnetic ordering. A neel transition was observed at approximately 150 K. 相似文献
25.
Heikki Kallio Kati Korkiasaari Olli Sjövall Jukka-Pekka Suomela Kaisa Linderborg 《Journal of the American Oil Chemists' Society》2006,83(5):407-413
TAG of butterfat were fractionated according to the type and degree of unsaturation into six fractions by silver-ion HPLC.
The fractions containing TAG with either cis-or trans-monoenoic FA were collected and fractionated further by reversed-phase HPLC to obtain fractions containing cis TAG of ACN:DB (acyl carbon number:double bonds) 48∶1, 50∶1, and 52∶1 as well as trans 48∶1, 50∶1, and 52∶1. The FA compositions of these fractions were elucidated by GC. The MW distribution of each fraction
was determined by ammonia negative-ion CI-MS. Each of the [M-H]− parent ions was fractionated further by collision-induced dissociation with argon, which gave information on the location
of cis-and trans-FA between the primary and secondary positions of TAG. The results suggest that the sn-positions of the monoenoic cis-and trans-FA depend on the two other FA present in the molecule. With 14∶0 FA in the TAG molecule, the 18∶1 FA in the sn-2 position are mostly present as cis-isomers. When there is no 14∶0 in the TAG molecule, the trans-18∶1 isomers seem to be more common in the sn-2 position. Also when other long-chain FA are present, the trans-isomers are more likely to be located in the secondary (sn-2) position. 相似文献
26.
Kati Tsch?pe Cristian Sch?ning J?rn Rutlin Tor Grande 《Metallurgical and Materials Transactions B》2012,43(2):290-301
Cathode autopsies are used frequently in the aluminum industry to investigate pot failure and the degradation of the cathode
lining. The materials observed in spent pot lining (SPL) has so far been assumed to reflect the sequence of layers from the
cathode to the nonreacted refractory lining as present during the operation of the cell. Here, we demonstrate that the thermal
gradient in the lining is reversed during cooling and that the physical appearance of the SPL is caused both by processes
taking place during operation and cooling of the shutdown cell. X-ray diffraction and microscopy of the SPL from three shutdown
cells revealed that sodium metal is the main component responsible for the chemical degradation of the refractory lining.
Two distinct reaction fronts were identified in the three SPL showing that sodium is penetrating deeper down into the lining
than the molten fluorides from the electrolyte. The mechanisms for the transport of sodium and bath components in the refractory
lining are proposed based on the experimental observations. The sodium penetration is inhibited by the formation of a viscous
barrier as suggested previously, but the current findings suggest that the barrier retards diffusion of O2– and F– anions rather than Na+ as proposed previously. 相似文献
27.
Effects of short‐ and long‐term Mediterranean‐based dietary treatment on plasma LC‐QTOF/MS metabolic profiling of subjects with metabolic syndrome features: The Metabolic Syndrome Reduction in Navarra (RESMENA) randomized controlled trial 下载免费PDF全文
28.
Kati Miettunen Minna Toivola Ghufran Hashmi Jyri Salpakari Imran Asghar Peter Lund 《Carbon》2011,(2):528-532
Carbon gel catalyst layers were used in dye solar cells. These layers were prepared on flexible plastic substrates at low temperatures (130 °C). The carbon gel, demonstrated excellent flexibility which is an important feature for roll-to-roll production and special applications of dye solar cells. The use of these low cost and highly flexible catalyst layers resulted in good photovoltaic performance; only 10% lower than dye solar cells with rigid glass-based counter electrodes prepared with thermal platinization at ∼400 °C temperature. 相似文献
29.
30.
The effects of operating conditions on emissions from masonry heaters and sauna stoves 总被引:1,自引:0,他引:1
Emissions from masonry heaters and sauna stoves were studied. In the sauna stove the production of organic gaseous carbon (OGC) at 10 gC kg?1 (per kilogram of fuel), carbon monoxide (CO) at 55 g kg?1, fine particle mass (PM1) at 5 g kg?1 and number emissions (N) at 1.8 × 1015 kg?1 was higher than in other measured appliances. In a modern technology masonry heater with a unique grate, the emissions were very low: 0.4 gC kg?1 OGC, 14 g kg?1 CO and 0.7 g kg?1 PM1. Conventional masonry heaters, using small logs, clearly produced higher emissions when compared to using large logs. Doubling the fuel load caused emission factors to increase by up to 4- times (OGC), except for the number emission, which decreased from 4.0 × 1014 to 2.0 × 1014 kg?1. From the conventional masonry heater 90% of the PM was emitted during the firing phase. Its combustion process is different to that in stoves or conventional open fireplaces. The insufficient supply of air, due to too fast pyrolysis, and increased ash release, due to the high combustion temperature, are the main parameters which cause high particle and gas emissions in masonry heaters and sauna stoves. 相似文献