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91.
本文根据宽条带与离层注浆联合开采的工程实践,推导了该种采矿方法地表移动理论计算公式,从理论上完善了该项技术,为更好地推广该技术打下理论基础. 相似文献
92.
We have investigated the scaling relationship between rheological behavior and concentration for both salt-free and saline solutions of hyaluronan (HA), and adopted three viscoelastic constitutive models to predict the linear/non-linear viscoelastic behavior of these aqueous solutions of HA with different molecular weights at different concentrations up to 20 mg/ml. A series of concentration equations are obtained to describe the influence of HA concentration on solution viscosity. Corresponding to dilute and semi-dilute concentration region, salt-free HA solutions have scaling relationship between specific viscosity and HA concentration as ηsp ∼ c1.0 and ηsp ∼ c3.5, respectively, while for 0.15 M NaCl HA solutions, the scaling exponents are 1.5 and 4.2, respectively. Simulation results indicate that these constitutive models have good applicability to describe quantitatively the rheological properties of HA entangled solutions under either dynamic or steady shear flow. In addition, the plateau modulus scaling of HA solutions can be well described by the concentration-dependent length scale. 相似文献
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Chidong Liu Laifei Cheng Xingang Luan Hui Mei 《Journal of the European Ceramic Society》2009,29(3):481-487
Tensile fatigue-stressed oxidation experiments were conducted at 1300 °C in oxidizing atmosphere to identify the failure modes and degradation mechanism of a SiC-coated carbon/carbon composite. Five peak fatigue stresses were selected between 90 and 150 MPa and the results showed that the higher the applied stress, the shorter the composite life. Electrical resistance of the composite was acquired in real-time. The composite resistance appeared a slight drop in the initial fatigue period and followed by a continuous increase until failure. Both the changes in modulus and resistance revealed the shrinking core mechanism in the fatigue-stressed oxidation experiments. A model was developed based on a half-cylinder oxidation pattern. Simulations were conducted on the basis of this model, and the results agreed with the experimental data fairly well. 相似文献
97.
Shunyi Zhao Fei Liu Xiaoli Luan 《International Journal of Adaptive Control and Signal Processing》2012,26(2):158-170
In this paper, the risk‐sensitive filtering method that relaxes the dependence on model accuracy is extended to nonlinear Markov jump systems (MJSs). In the method, the so‐called reference probability technique together with particle approximation is utilized to derive the risk‐sensitive filter in nonlinear non‐Gaussian framework. The novelty of the proposed approach is that a ‘risky’ interacting resampling step is performed to both moderate the modeling uncertainties and to solve the problem of particle explosion. A designer‐chosen parameter named risk‐sensitive parameter allows us to make a trade‐off between the filtering accuracy for the nominal model and the robustness to uncertainties. With a meaningful example, it shows that the developed method can outperform the widely used method‐particle filter and interacting multiple model‐particle filter in nonlinear MJSs with uncertainties. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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The star-shaped polymethyl acrylate (PMA) was synthesized by single electron transfer living radical polymerization (SET-LRP)
at 30 °C in dimethyl sulfoxide, using 2,2-dibromomethyl-1,3-dibromopropane as the multifunctional initiator, Cu0 powder and tris-(2-dimethylamino ethyl)amine (Me6-TREN) as catalyst. The structure of polymer was analyzed by 1H NMR, and the results showed that the star-shaped PMA had perfect chain ends (–Br) retention. In addition, the polymerization
proceeded smoothly and the time dependence of ln([M]0/[M]) was linear, which could indicate a first order propagation rate with respect to both radicals and monomer concentration,
the polymerization was the living polymerization. The M
n and M
w/M
n of polymer were being measured by Gel Permeation Chromatography. The k
papp = 0.0367 h−1 and the conversion was 36.3% at 16 h, meanwhile the M
nGPC of the polymer was 13,300 and the M
w/M
n was 1.40. 相似文献