Narrow Results

Self-trapping transition of the acoustic polaron in slab is researched by calculating the polaron ground state energy and the first derivative of the ground state energy with respect to the electron–phonon coupling. It is indicated that the possibility of self-trapping transition for acoustic polaron in slab fall in between 3D and 2D systems. The electron may be self-trapped in slab systems of GaN, AlN and alkali halides, if the slab systems are thinner than one over ten of the length unit ℏ/mc.

In this paper we study the problems of separability of two disjoint point sets in 3D by multiple criteria extending some notions on separability of two disjoint point sets in the plane.

We study the limiting behavior of a Schrödinger–Poisson system describing a three-dimensional quantum gas that is confined along the vertical z-direction in a fine slab. The starting point is the three-dimensional Schrödinger–Poisson system with Dirichlet conditions on two horizontal planes z = 0 and z = ε, where the small parameter ε is the scale width of the slab. The limit ε → 0 appears to be an infinite system of two-dimensional nonlinear Schrödinger equations. Our strategy combines a refined analysis of the Poisson kernel acting on strongly confined densities and a time-averaging process that allows us to deal with the fast time oscillations.

This paper studies the subway-induced vibrations on two adjacent masonry structures in Shanghai with focus on the vibration level and frequency. The results show that: (1) the vibration levels of the two masonry structures in three directions are all higher during the peak traffic hours than the off-peak hours and are higher in the daytime than at night. In addition, they are higher at the mid-span of the floor than the wall-floor junctions and staircase. (2) The parameters of the numerical model were calibrated by the measured vibration response. The slab properties, room size, and other factors can affect the vibration response distribution. (3) The vertical vibrations in the rooms with precast slab are greater than those with cast-in-situ slab. The vertical vibrations at the ash seam between the precast slabs are amplified. In addition, the room depth has a small effect on the vibration intensity. The relationship between the room depth and the vibration intensity depends on the relative width and depth of the room. (4) The width of the room has a significant effect on the vertical vibration. The floor corner and surrounding wall constraint conditions greatly affect the vibration intensity.

This study comprehensively explores the dynamic behavior of a slender slab due to the excitation of pedestrian traffic. Three kinds of excitation models are adopted to describe the vibration of the slab induced by pedestrians. A comparison of the structural responses shows that the bipedal model results in larger vibrations than the mass–spring–damper or pseudo-excitation models. Further research indicates that the pedestrians evidently alter the dynamic properties of the slab by affecting its frequency and damping capacity. The slab tends to be more flexible at a lower frequency as the pedestrian walks across its surface while its damping capacity is improved. In contrast, the slab can increase the frequency, while decreasing the damping of the pedestrian model. Thus, the slab also alters the properties of the pedestrians. In addition, an investigation of the bipedal model parameters indicates that the variations of the leg stiffness, damping, and body mass have distinct effects on the slab characteristics and vibrations. In order to assess the response of the slab to a crowd, a new simplified theory is introduced to describe the dynamic properties of the slab under multi-layout excitations, including human influences resulting from different body properties. The results of this study provide potential ways for understanding the vibratory mechanisms of slender structures such as footbridges, grandstands, or stations under crowd excitations.

Plane-wave pseudopotential density functional theory (DFT) periodic slab calculations were performed using the generalized gradient approximation (GGA) to investigate the adsorption of nitric oxide (NO) on the (001) surface of Ag. We examined three different adsorption sites perpendicular with respect to the surface and a position that the axis of NO molecule was tilted from the upright. The adsorption of NO in the fourfold hollow site was favored, with a binding energy of 45.47 kJ/mol.

A three-dimensional mathematical transient heat transfer model for the prediction of temperature distribution within the slab has been developed by considering the thermal radiation in the walking-beam-type reheating furnace chamber. The steel slabs are heated up through the non-firing, preheating, 1st-heating, 2nd-heating, and soaking zones in the furnace, respectively, where the furnace wall temperature is function of time. Comparison with the in-situ experimental data from Steel Company in Taiwan shows that the present heat transfer model works well for the prediction of thermal behavior of the slab in the reheating furnace. The effects of different skid button height (H=60mm, 90mm, and 120mm) and different gap distance between two slabs (S=50mm, 75mm, and 100mm) on the slab skid mark formation and temperature profiles are investigated. It is found that the skid mark severity decreases with an increase in the skid button height. The effect of gap distance is important only for the slab edge planes, while it is insignificant for the slab central planes.

Using an airport expansion project with frame structure as an example, this paper studied the seismic performance of reinforced concrete frame structure’s beam-column joints under the action of strong earthquake. With Abaqus software, the response of structure in different seismic magnitude and peak acceleration under EL-Centro wave, Accel artificial wave and Taft wave were calculated, and the seismic performance of local frame node is also analyzed. The analysis results indicate that considering floor, the effect on stiffness of the beam structure is significantly improved and structural lateral stiffness is increased, but the “strong beam weak column” destroy appears easily. If reinforcement ratio and stirrup ratio are improved, it will enhance the strength of column and restrict the concrete at the end of the play, which also contributes to achieve “strong column weak beam” type.

The vibration analysis model of plate mill is established based on the multi-body dynamics theory. Through simulation analysis, the relationship between the vibration displacement and time of the work roller in different conditions is obtained. Under different damping conditions, the vibration characteristics of the upper and lower working rollers are obtained, which can use in analyzing the mechanism and vibration reasons of the vibration of rolling mill. The results of the research can improve the quality of the products.