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排序方式: 共有576条查询结果,搜索用时 15 毫秒
41.
Badr Bassou Nolven Guilhaume Eduard Emil Iojoiu David Farrusseng Karine Lombaert Daniel Bianchi Claude Mirodatos 《Catalysis Today》2011,159(1):103-143
Following the development of a high-throughput (HT) methodology for the evaluation of diesel soot oxidation catalysts in a 16 parallel channels reactor, a library of over 60 catalysts was tested under optimized conditions. The catalyst compositions were chosen to include solids which specific properties like oxygen storage capacity, oxygen mobility and ionic conductivity. The key parameters for high activity appear related to the presence of active and mobile surface oxygen species, and to an appropriate catalyst particle size in order to favour the number of contacts with the soot. In contrast, high oxygen storage capacity and bulk oxygen ion mobility do not appear as relevant properties for high catalytic activity. Nine new formulations were found to perform better than the reference catalyst “high surface area (HSA) ceria” (Rhodia). 相似文献
42.
Karen G. Dvoyan David B. Hayrapetyan Eduard M. Kazaryan Ani A. Tshantshapanyan 《Nanoscale research letters》2009,4(2):130-137
Energy level structure and direct light absorption in a cylindrical quantum dot (CQD), having thin falciform cross section, are studied within the framework of the adiabatic approximation. An analytical expression for the energy spectrum of the particle is obtained. For the one-dimensional “fast” subsystem, an oscillatory dependence of the wave function amplitude on the cross section parameters is revealed. For treatment of the “slow” subsystem, parabolic and modified Pöschl-Teller effective potentials are used. It is shown that the low-energy levels of the spectrum are equidistant. In the strong quantization regime, the absorption coefficient and edge frequencies are calculated. Selection rules for the corresponding quantum transitions are obtained. 相似文献
43.
For a fixed-source calculation in a multiplying system, the variance in the neutron-chain length can create an unstable calculation and a neutron flux with high variance. In this paper an analytical frame is derived to calculate a priori the variance of the neutron flux in a simple model of a fixed-source calculation. This method is then used to find better variance reduction techniques not only for this simplified problem, but also for general cases. 相似文献
44.
Eduard P.P.A. Derks 《Food quality and preference》2010,21(3):324-329
This paper proposes panel concordance analysis (PANCA) as a tool for panel leaders to identify disconsensus between the panelists on the sensory attributes used. PANCA summarizes the sensory data ([products × panelists × replicates] × attributes) by a low-rank approximation which is penalized for disconsensus (disagreement) between the panelists. When all the panelists agree on the sensory attributes used, the disconsensus penalty will have a negligible effect. However, if the assumption of good consensus is not supported by the data, considerable residual errors will arise. Consequently, PANCA can be used to identify difficult sensory attributes or even poor/deviating panelists which requires further training or could call for an alternative data processing strategy. It is also demonstrated that PANCA can be used to apply a multivariate ANOVA decomposition like in ASCA (ANOVA simultaneous component analysis). Theory and applications are explained by means of a real-life example from industrial sensory practice. 相似文献
45.
We describe annotation of multiword expressions (MWEs) in the Prague dependency treebank, using several automatic pre-annotation steps. We use subtrees of the tectogrammatical tree structures of the Prague dependency treebank to store representations of the MWEs in the dictionary and pre-annotate following occurrences automatically. We also show a way to measure reliability of this type of annotation. 相似文献
46.
Gelinck GH Huitema HE van Veenendaal E Cantatore E Schrijnemakers L van der Putten JB Geuns TC Beenhakkers M Giesbers JB Huisman BH Meijer EJ Benito EM Touwslager FJ Marsman AW van Rens BJ de Leeuw DM 《Nature materials》2004,3(2):106-110
At present, flexible displays are an important focus of research. Further development of large, flexible displays requires a cost-effective manufacturing process for the active-matrix backplane, which contains one transistor per pixel. One way to further reduce costs is to integrate (part of) the display drive circuitry, such as row shift registers, directly on the display substrate. Here, we demonstrate flexible active-matrix monochrome electrophoretic displays based on solution-processed organic transistors on 25-microm-thick polyimide substrates. The displays can be bent to a radius of 1 cm without significant loss in performance. Using the same process flow we prepared row shift registers. With 1,888 transistors, these are the largest organic integrated circuits reported to date. More importantly, the operating frequency of 5 kHz is sufficiently high to allow integration with the display operating at video speed. This work therefore represents a major step towards 'system-on-plastic'. 相似文献
47.
This paper presents costs per US motor vehicle crash victim differentiated into many more diagnostic categories than prior estimates. These unit costs, which include the first keyed to the 1990 edition of Abbreviated Injury Scale (AIS) threat-to-life severity scores, are reported by body part, whether a fracture/dislocation was involved, and the maximum AIS score among the victim's injuries. This level of detail allows for a more accurate estimation of the social costs of motor vehicle crashes. It also allows for reliable analyses of interventions targeting narrow ranges of injuries. The paper updates the medical care data underlying the US crash costs from 1979 to 1986 to the mid 1990s and improves on prior productivity cost estimates. In addition to presenting the latest generation of crash victim costs, this paper analyzes the effects of applying injury costs classified by AIS code from the 1985 edition to injury incidence data coded with the 1990 edition of AIS. This long-standing practice results in inaccurate cost-benefit analyses that typically overestimate benefits. This problem is more acute when old published costs adjusted for inflation are used rather than the recent costs. 相似文献
48.
Assessment of average,population and individual bioequivalence in two- and four-period crossover studies 总被引:3,自引:0,他引:3
Wijnand HP 《Computer methods and programs in biomedicine》2003,70(1):21-35
The aim of bioequivalence studies is to assess the equivalence of two pharmaceutical formulations of the same active drug substance. Currently three types of bioequivalence are distinguished: average, population and individual bioequivalence. Average and population bioequivalence can be assessed in two-period (non-replicated) crossover studies, whereas individual bioequivalence requires three- or four-period replicated studies, with a preference for four-period studies. The PC-program BIOEQV80 is presented for the statistical analysis of average and population bioequivalence from two-period crossover studies. The program BIOEQ2X2 is presented for the statistical analysis of all three types of bioequivalence from four-period replicated crossover studies. The statistical aspects of population and individual bioequivalence are based on a recent Guidance issued by the US Food and Drug Administration. 相似文献
49.
A cross-sectional study was performed in eight companies, comprising 32 buildings without previously recognized indoor air problems. Engineers filled in a technical questionnaire on building characteristics, floor surface materials, ventilation, cleaning procedures, heating and cooling. A total of 3562 employees returned questionnaires on individual factors, workload, perceived physical work environment, allergy and symptoms. Frequent symptoms were feeling of fatigue or heavy-headedness, eye irritation, and dry facial skin. Women reported symptoms more frequently than men. Employees with allergy had a 1.8-2.5 times risk of reporting a high score for general, skin, or mucosal symptoms. The risk of a high symptom score increased with daily visual display unit (VDU) work time. Passive smoking and psychosocial load were also relatively strong predictors of symptoms. Weekly cleaning as compared with a frequency of cleaning two to four times a week increased the risk of symptoms. Adjusted odds ratio for a high general symptoms score from infrequent cleaning was 1.5 (95%CI 1.1-2.0). A high ventilation flow or central ventilation unit filter EU7 vs. EU8 seemed to be associated with an increased risk of general symptoms. Absence of local temperature control increased the risk of mucosal symptoms. 相似文献
50.
We show that the sup-t-norm and inf-residuum types of fuzzy relational equations, considered in the literature as two different types, are in fact two particular instances of a single, more general type of equations. We demonstrate that several pairs of corresponding results on the sup-t-norm and inf-residuum types of equations are simple consequences of single results regarding the more general type of equations. We also show that the new type of equations subsumes other types of equations such as equations with constraints on solutions, examples of which are fuzzy relational equations whose solutions are required to be crisp (ordinary) relations. 相似文献