Multiscale modeling of rapid granular flow with a hybrid discrete-continuum method

Both discrete and continuum models have been widely used to study rapid granular flow, discrete model is accurate but computationally expensive, whereas continuum model is computationally efficient but its accuracy is doubtful in many situations. Here we propose a hybrid discrete-continuum method to profit from the merits but discard the drawbacks of both discrete and continuum models. Continuum model is used in the regions where it is valid and discrete model is used in the regions where continuum description fails, they are coupled via dynamical exchange of parameters in the overlap regions. Simulation of granular channel flow demonstrates that the proposed hybrid discrete-continuum method is nearly as accurate as discrete model, with much less computational cost

Study of Risk Evaluation for Complex Projects under BIM and IPD Collaborative Pattern Based on Neighborhood Rough Sets

Faced with the existing problems in the construction industry, project managers have been aware that traditional project delivery patterns cannot satisfy the current building industry\u27s pursuit of high-quality economic benefits or cope with the increasing volume and complexity of modern buildings. Therefore, whole-process comprehensive management has become a new development trend for engineering projects, the traditional project delivery pattern should be changed, and early-stage communication, cooperation, and information sharing among project participants should be strengthened. As for the BIM and IPD collaborative pattern, the emphasis is laid on collaboration among project members, and the core idea lies in benefit and risk sharing and full consideration of human resources, commercial structure and engineering system of projects. The advent of IPD pattern has well solved problematic issues encountered in engineering projects, where risk problem has attracted the highest attention. Risk factors of IPD projects were reduced and screened out based on attribute reduction theory of rough sets, and primary risk factors influencing smooth implementation of IPD projects were obtained

Baicalein administration protects against pentylenetetrazole-induced chronic epilepsy in rats

Purpose: To investigate the protective effect of baicalein against chronic seizures in pentylenetetrazole induced epilepsy in a rat model.Methods: A rat model of chronic epilepsy was prepared by administration of pentylenetetrazole at a dose of 35 mg/kg to Sprague-Dawley rats. The animals were divided into 6 groups (5 rats/group): normal control, model (untreated epilepsy) and four treatment groups that received separately, intraperitoneal injection of 20, 30, 40 and 50 mg/kg baicalein, respectively, on alternate days for 30 days. On each day following baicalein treatment, behavioural alterations in the  rats were assessed.Results: Analyses of behavioural changes revealed significant (p < 0.05) decrease in pentylenetetrazole-induced convulsions by baicalein treatment at a dose of 50 mg/kg. Immunohistochemical studies revealed that treatment with baicalein caused significant (p < 0.05) dosedependent reductions in the levels of inducible nitric oxide synthase (iNOS). Baicalein treatment inhibited alterations in cell morphology, and also inhibited pentylenetetrazole-induced increase in the proportion of glial fibrillary acidic protein (GFAP)-positive cells in a dose-dependent manner (p < 0.05). Real-time polymerase chain reaction (RT-PCR) analysis showed that baicalein significantly inhibited the expression of mRNA of NR1 subunit N methyl D aspartic acid (NMDA) receptor, without any effect on the expression of the NR2b (N-methyl D-aspartate receptor subtype 2B ) subunit mRNA (p < 0.05).Conclusion: These results indicate that baicalein inhibits pentylenetetrazole-induced chronic seizures in rats via reduction in astrocytes, inhibition of neuronal death and reduction of NR1 mRNA expression. Thus, baicalein has a potential for development into a new drug for the treatment of chronic epilepsy.Keywords: Pentylenetetrazole, Epilepsy, Baicalein, Convulsion, Inhibition, behavioural changes, Hippocampu

Influence of CO2-laser pulse parameters on 13.5 nm extreme ultraviolet emission features from irradiated liquid tin target

Laser-produced plasma (LPP) induced during irradiation of a liquid tin droplet with diameter of 150 um and 180 um by CO2 laser pulse with various pulse durations and energies is considered. The two-dimensional radiative magnetohydrodynamic (RMHD) plasma code is used to simulate the emission and plasma dynamics of multicharged ion tin LPP. Results of simulations for various laser pulse durations and 75-600 mJ pulse energies with Gaussian and experimentally taken temporal profiles are discussed. It is found that if the mass of the target is big enough to provide the plasma flux required (the considered case) a kind of dynamic quasi-stationary plasma flux is formed. In this dynamic quasi-stationary plasma flux, an interlayer of relatively cold tin vapor with mass density of 1-2 g/cm3 is formed between the liquid tin droplet and low density plasma of the critical layer. Expanding of the tin vapor from the droplet provides the plasma flux to the critical layer. In critical layer the plasma is heated up and expands faster. In the simulation results with spherical liquid tin target, the CE into 2${\pi}$ is of 4% for 30 ns FWHM and just slightly lower - of 3.67% for 240 ns FWHM for equal laser intensities of 14 GW/cm2. This slight decay of the in-band EUV yield with laser pulse duration is conditioned by an increasing of radiation re-absorption by expanding plasma from the target, as more cold plasma is produced with longer pulse. The calculated direction diagrams of in-band EUV emission permit to optimize a collector configuration

Performance of steel frames with new lightweight composite infill walls under curvature ground deformation

In this paper, the structural performance of steel frames with novel lightweight composite infill walls is experimentally and numerically investigated under curvature ground deformation, which is a common consequence of ground mining activities that can cause significant effects on structures and buildings in these areas. A new structural form that combines steel frames and lightweight composite infill walls has recently been used; its performance under curvature ground deformation is of great interest but still not entirely clear. This study compares the mechanical behavior of the open-frame, the closed-frame with mudsill, and the closed-frame with infill walls, through experimental testing under positive and negative curvature ground deformations. Structural responses such as basement counterforce, additional strains at different key locations, and effects of mudsill and infill walls are evaluated. In addition, 3D finite element models are established to simulate the performance of the tested samples and are validated by comparing the results against those from experiments. After validation, the numerical model is applied to a few complex structures incorporating the composite infill walls to investigate their structural performance under both positive and negative curvature ground deformation. It has been found that steel frames with the new composite infill walls can considerably increase the stiffness of structures in resisting ground deformation and re-distribute the loads amongst the beam and column members in the frame. Failure modes for the structures can also be changed by shifting the most dangerous ones from the upper part of the frame to the lower part. Moreover, it has been found that the vertical force of the infill walls is more sensitive to curvature ground deformation than the horizontal force. Further, the influence of the infill wall on the column is more significant, in comparison to that on the beam of the frame

Direct numerical simulation of Taylor-Couette flow with vertical asymmetric rough walls

Direct numerical simulations are performed to explore the effects of rotating direction of the vertical asymmetric rough wall on the transport properties of Taylor-Couette (TC) flow up to a Taylor number of $\textit{Ta} = 2.39 \times 10^7$. It is shown that compared to the smooth wall, the rough wall with vertical asymmetric strips can enhance the dimensionless torque \textit{Nu}$_\omega$, and more importantly, at high \textit{Ta} clockwise rotation of the inner rough wall (the fluid is sheared by the steeper slope side of the strips) results in a significantly bigger torque enhancement as compared to the counter-clockwise rotation (the fluid is sheared by the smaller slope side of the strips) due to the larger convective contribution to the angular velocity flux, although the rotating direction has a negligible effect on the torque at low \textit{Ta}. The larger torque enhancement caused by the clockwise rotation of vertical asymmetric rough wall at high \textit{Ta} is then explained by the stronger coupling between the rough wall and the bulk due to the larger biased azimuthal velocity towards the rough wall at the mid-gap of TC system, the increased intensity of turbulence manifesting by larger Reynolds stress and thinner boundary layer, and the more significant contribution of the pressure force on the surface of rough wall to the torque.Comment: 17 pages,11 figure