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91.
Selective Template Removal by Thermal Depolymerization to Obtain Mesostructured Molybdenum Oxycarbide
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Martin Schieder Thomas Lunkenbein Carina Bojer Martin Dulle Julia vom Stein Gudrun Auffermann Tina Löbling Judith Schöbel Holger Schmalz Josef Breu 《无机化学与普通化学杂志》2015,641(10):1829-1834
The carbon content of mesostructured organic‐inorganic hybrid material of a cylindrical block copolymer template of poly(2‐vinylpyridine)‐block‐poly(allyl methacrylate) (P2VP‐b‐PAMA) and ammonium paramolybdate (APM) could be reduced by thermal depolymerization. By calcination in vacuo at 320 °C the PAMA core can be completely removed while the remaining P2VP brush preserves the mesostructure. The P2VP‐APM composite can then be carburized in‐situ to MoOxCy in a second pyrolysis step without any additional carbon source but P2VP. The molybdenum oxycarbide nanotubes obtained, form hierarchically porous non‐woven structures, which were tested as catalyst in the decomposition of NH3. They proved to be catalytically active at temperatures above 450 °C. The activation energy was estimated from an Arrhenius Plot to be 127 kJ · mol–1. 相似文献
92.
93.
Simultaneous Titration of Ternary Mixtures of Pb(II), Cd(II) and Cu(II) with Potentiometric Electronic Tongue Detection 下载免费PDF全文
An automatic titration method is reported to resolve ternary mixtures of transition metals (Pb2+, Cd2+ and Cu2+) employing electronic tongue detection and a reduced number of pre‐defined additions of EDTA titrant. Sensors used were PVC membrane selective electrodes with generic response to heavy‐metals, plus an artificial neural network response model. Detection limits obtained were ca. 1 mg L?1 for the three target ions and reproducibilities 3.0 % for Pb2+, 4.1 % for Cd2+ and 5.2 % for Cu2+. The system was applied to contaminated soil samples and high accuracy was obtained for the determination of Pb2+. In the determination Cd2+ and Cu2+, sample matrix showed a significant effect. 相似文献
94.
参数灵敏度分析的神经网络方法及其工程应用 总被引:10,自引:0,他引:10
在系统分析中,参数灵敏度分析不仅为判断各系统参数的重要性大小提供了依据,量化的灵敏度指标也是后续参数估计的前提。然而,在多效实际系统中,系统参数与系统状态间的显式函数关系不易得到,导致一阶灵敏度指标无法直接求取。简化的单因素分析方法亦存在模型粗糙、精度不高的缺点。本文研究采用人工神经网络的高精度泛化映射,通过少量样本的训练,建立复杂系统中多个系统参数与系统状态间的近似映射关系,继而推导得到统一的灵敏度计算列式。简单结构的神经网络方法和解析方法的对比计算显示了方法的有效性和可靠性。最后,应用该法对某斜拉桥结构的荷载参数和刚度参数进行了考查,得到一般性结论。 相似文献
95.
基于网络技术的综合导航系统研究 总被引:1,自引:1,他引:1
通过对局域网的分析,提出了基于1553B数据总线技术综合导航系统设计方案,并对其可行性进行了充分论证,这种方案在很大程度上保证了系统的可靠性和实时性。 相似文献
96.
STABILITY ANALYSIS OF HOPFIELD NEURAL NETWORKS WITH TIME DELAY 总被引:3,自引:0,他引:3
IntroductionInrecentyearsthedynamicbehaviorofthefollowingHopfieldneuralnetworksmodelwithtimedelayhavebeeninvestigatedthoroughlyCi xi(t) =-xiRi + ∑nj=1Tijfj(xj(t-τij) ) +Ii (i=1 ,2 ,… ,n) ,( 1 )whereRi,CiandIirepresentresistance ,capacitanceandelectriccurrent.Ri,Ciarepa… 相似文献
97.
This paper describes the formulation of a quasi-1-D network model, referred to as the ‘bubble model’, and its application
for simulating particle transport and filtration through a granular filter bed. The model comprises a series of homogeneous
sites linked through bundles of cylindrical bonds that represent flow pathways through distributions of pores and pore throats.
This model incorporates pore scale processes of particle sieving and infiltration are based on numerical simulations described
in a companion paper. The modeling of infiltration is further refined based on detailed experimental observations and measurements
of the filtration of a dilute suspension of acrylic particles through a column of glass beads reported by Yoon et al. (2005 Water Resour. Res., to appear). Their data distinguish (a) between the collection of particles on grain surfaces and at grain-to-grain contact
points, and (b) between particles that are fully entrapped and those that are hindered (temporarily collected) and can later
become detached. These effects are represented by two parameters that characterize the probability of attachment and are linked
to the surface roughness of the grains; one that describes the minimum particle size that can be fully entrapped, and one
that describes the detachment rate. These parameters can be readily calibrated from conventional measurements of effluent
concentration and effluent particle size distribution. Detailed comparisons with the data reported by Yoon et al. show that the proposed bubble model is able to achieve reliable predictions of the spatial distribution of particles within
the filter bed following phases of particle injection and washing. 相似文献
98.
Different from the approaches used in the earlier papers, in this paper, the Halanay inequality technique, in combination
with the Lyapunov method, is exploited to establish a delay-independent sufficient condition for the exponential stability
of stochastic Cohen–Grossberg neural networks with time-varying delays and reaction–diffusion terms. Moreover, for the deterministic
delayed Cohen–Grossberg neural networks, with or without reaction–diffusion terms, sufficient criteria for their global exponential
stability are also obtained. The proposed results improve and extend those in the earlier literature and are easier to verify.
An example is also given to illustrate the correctness of our results. 相似文献
99.
100.
A new constitutive equation for whole human blood is derived using ideas drawn from temporary polymer network theory to model the aggregation and disaggregation of erythrocytes in normal human blood at different shear rates. Each erythrocyte is represented by a dumbbell. The use of a linear spring law in the dumbbells leads to a multi-mode generalized Maxwell equation for the elastic stress and both the relaxation times and viscosities are functions of a time-dependent structure variable. An approximate constitutive equation is derived by choosing a single mode corresponding to the cell aggregate size where the largest number of cells are to be found. This size is identified in the case of steady flows. The model exhibits shear-thinning, viscoelasticity and thixotropy and these are clearly related to the microstructural properties of the fluid. Agreement with the experimental data of Bureau et al. [M. Bureau, J.C. Healy, D. Bourgoin, M. Joly, Rheological hysteresis of blood at low shear rate, Biorheology 17 (1980) 191–203] in the case of a simple triangular step shear rate flow is convincing. 相似文献