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This paper presents a computational microstructure model to estimate the progressive moisture damage of multiphase asphaltic paving mixtures. Moisture damage because of water transport is incorporated with mechanical loading through a finite element method. To simulate nonlinear damage evolution in the mixtures, the model includes Fickian moisture diffusion, a cohesive zone model to simulate the gradual fracture process, and a degradation characteristic function to represent the reduction of material properties because of moisture infiltration. With the model developed, various parametric analyses are conducted to investigate how each model parameter affects the material‐specific moisture damage mechanism and damage resistance potential of the mixtures. Analysis results clearly demonstrate the significance of physical and mechanical properties of mixture components and geometric characteristics of microstructure for the better design of asphaltic paving mixtures and roadway structures. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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A. Mazure P. Katgert R. Den Hartog A. Biviano P. Dubath E. Escalera P. Focardi D. Gerbal G. Giuricin B. Jones O. Le Fèvre M. Moles J. Perea G. Rhee 《Astrophysics》1995,38(4):367-369
A statistically reliable distribution of velocity dispersions free from biases and systematic errors for a sample of ACO clusters is obtained. This distribution is compared with other data and model predictions.Published in Astrofizika, Vol. 38, No. 4, pp. 654–658, October–December, 1995. 相似文献
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This study investigated the effect of cumulative overland flow on rill erodibility and critical shear stress on native surface roads in central Idaho. Rill erodibility decreased exponentially with increasing cumulative overland flow depth; however, critical shear stress did not change. The study demonstrated that road erodibility on the studied road changes over the course of one or more consecutive overland flow events. Therefore, model simulations that fail to take into consideration this change will probably over-estimate sediment yields. An exponential function describing the relationship between rill erodibility and cumulative overland flow depth is presented as a basis for future model development for simulating erosion on native surface roads. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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Expression of superoxide dismutase (SOD) genes from the copper-exposed polychaete, Neanthes succinea
To evaluate the superoxide dismutase (SOD) genes as a potential indicator of environmental stress, we cloned and sequenced the full-length cDNA of a Cu/Zn-SOD and Mn-SOD genes from the marine polychaete, Neanthes succinea. Ns-Cu/Zn- and Mn-SOD expression was measured using quantitative real-time RT-PCR in response to the oxidative stress induced by copper in the form of CuCl2. Ns-Cu/Zn-SOD expression increased in a dose dependent manner but the increase of Mn-SOD expression was evident only at a high concentration of copper. Particularly, Ns-Mn-SOD dramatically increased in the 72 μg/L CuCl2-exposed groups, indicating that both Ns-SOD genes were induced by copper exposure. These results suggest that Ns-Cu/Zn- and Ns-Mn-SOD would play important roles in the detoxification of cellular oxidative stresses in the polychaete, N. succinea. Furthermore, as part of field work, the marine polychaete, N. succineaCu/Zn-SOD mRNA collected from the polluted area was accordingly upregulated in expression but not for NS-Mn-SOD. 相似文献
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Partitioning tracer method for quantifying the residual saturation of refined petroleum products in saturated soil 总被引：1，自引：1，他引：0
The effective site assessment is crucial to the successful remediation of the subsurface contaminated with light nonaqueous
phase liquids (LNAPLs). Recent studies showed that large spatial volumes of the subsurface contaminated with LNAPLs could
be investigated with the partitioning tracer method. This study investigated the applicability of the partitioning tracer
method for detecting and quantifying refined petroleum products in a saturated aquifer containing alluvial soil or weathered
granite soil. In the batch-partitioning experiments, the partition coefficients of alcohol tracers between the petroleum mixture
and water were measured, and they were found to be increased in proportion to the boiling points of the alcohol tracers when
the molecular weights of the alcohol tracers were similar. The sorption isotherm experiments indicated that a considerable
amount of 4-methyl-2-pentanol was sorbed into Jumunjin sand (JS) or weathered granite soil (WGS). In the column experiments,
it was confirmed that the partitioning tracer method could be used as a method for detecting the presence of the petroleum
mixture in saturated soil, and the residual saturation of the petroleum mixture in the soil column prepared by firstly contaminating
with the petroleum mixture and secondly saturating with water was measured higher than that in the soil column prepared by
firstly saturating and secondly contaminating. The highest accuracy of estimation using the partitioning tracer method was
found for 2-ethyl-1-butanol and the lowest accuracy was found for 4-methyl-2-pentanol. 相似文献
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Ships experience roll motion due to waves in a seaway. Therefore, fin stabilizers are installed to stabilize such roll motion. A fin stabilizer is effective at reducing the roll motion at moderate speeds but not at low speeds. Recently, pod propellers have been used with fin stabilizers for roll stabilization. In the paper, a MIMO (multi-input multi-output) optimal control system that has two control inputs such as fin stabilizers and pod propellers is designed. The LQR (linear quadratic regulator) control algorithm is applied to reduce the roll motion of cruise ships in regular waves. Also, the nominal plant and the frequency-weighted LQR are applied to reduce the roll motion in irregular waves. The roll motion of cruise ships is effectively reduced when the fin and pod propeller are used as the control actuators at low speeds. The optimal control gain is easily found when the frequency-weighted LQR is applied. 相似文献
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We present new evidence that first ranked galaxies are aligned with their parent cluster and with the direction of the nearest neighbour cluster (scale 15h
–1 Mpc). The effect is stronger for cD and gE galaxies than for first-ranked galaxies of later type. The relevance of this result for different galaxy formation scenarios is discussed. In hierarchical clustering scenarios like the cold dark matter theory, galactic halos and clusters of galaxies are expected to have moderate asphericity. We present some numerical results of an on-going study of the dissipationless collapse of moderately aspherical systems. Our results indicate that the central part of the collapsed and virialized system does show the large scale elongation imposed by the initial conditions. It is pointed out that this may have important implications also for the properties of disk galaxies in dark halos. 相似文献