Conditions Of Different Thicknesses Research Articles

Study on seismic response of liquefiable soil-pile group considering pile cap and soil contact

In this paper, based on the centrifuge test of liquefied soil-pile foundation system, a numerical model of liquefied soil-pile foundation-structure system is modelled by using OpenSees platform. In the simulation model, the friction effect between liquefied ground and low pile cap is considered, and the method of establishing virtual nodes is used to deal with the non-linear contact between liquefiable soil and low pile cap. The rationality and effectiveness of the numerical simulation method adopted in this paper has been verified and evaluated by comparing with the results of centrifuge experiments. A typical liquefaction soil-pile integrated finite element model is modelled using validated numerical simulation methods. The law of seismic response of the pile foundation system with different embedding depths of pile cap, different contact modes between the pile cap and saturated sand, and the thickness of the overlying saturated loose sand layer are discussed. The results show that the pile cap and pile foundation in the high pile cap system show higher seismic response characteristics than the other three low pile cap system conditions; Under the condition of different contact modes between the pile cap and the surrounding saturated sand, the peak bending moment and residual displacement of the pile foundation calculated by the bond contact are larger than calculated by the friction contact, and the deformation of pile is more significant. By comparing the working conditions of different thicknesses of overlying saturated loose sand layer, it is found that the degree of liquefaction in shallow soils is less affected by thickness of the saturated loose sand. As the thickness of saturated loose sand layer increases, the peak bending moment and residual displacement at the top of the pile also gradually increase. The change of peak bending moment at the soil interface is more obvious.

Influence of multilayer graphene doping concentrations on detection properties of MLG/Mg2Si/Si heterojunction photodetector

AbstractThis paper presents a structural model for a photodetector (PD) with a multilayer graphene (MLG)/Mg2Si/Si heterojunction and an examination of the impacts of MLG doping concentrations on the detection abilities of these PDs. The results show that under the conditions of different thicknesses of the monolayer, five‐layer, and 10‐layer grapheme (Gr), the detection properties of heterojunction PDs degrade as the doping concentrations of the MLG layer increase from 1013 to 1017 cm−3, respectively. The electric field intensity at the heterojunction MLG/Mg2Si interface diminishes as MLG doping concentrations increase. The effectiveness of photo‐generated carrier separation and transfer in the space charge area at the MLG/Mg2Si interface therefore declines. The detection properties are outstanding when the MLG doping concentration is 1013 cm−3. The maximum values of peak responsivity, external quantum efficiency (EQE), detectivity (D*), and on/off ratio are found to be 0.81 A/W, 103.28%, 6.1×1010 Jones, and 610.5, respectively. A minimum peak noise equivalent power (NEP) of 1.64×10−11 WHz−1/2 is obtained. The results also show that PD has a great potential as a replacement for other visible and near‐infrared (NIR) poisonous devices. The facts presented above provide a theoretical framework for the fabrication and application of optoelectronic devices.

Analysis method of the water inrush and collapse in jointed rock mass tunnels: A case study

Water inrush disaster occurs easily when the tunnel is close to the water rich fault fracture zone. To clarify the disaster evolution process and the critical thickness of the water-resistant rock mass is the key problem of the prevention and control of water inrush disaster in jointed rock tunnel. However, the water inrush disaster in jointed rock tunnels involves solid-fluid interaction, and the conventional single-phase numerical method is difficult to realize the real simulation of the disaster. To solve this problem, we gave full play to the advantages of the discontinuous deformation analysis method (DDA) in simulating solid motion and the smoothed particle hydrodynamics method (SPH) in simulating fluid motion, and the two-dimensional DDA-SPH (2D DDA-SPH) method was used to simulation the solid-fluid interaction in the water inrush disasters. Firstly, the 2D DDA-SPH method was used to replicate the solitary wave experiment, named Scott Russell's wave generator, and the result of the simulation was almost the same with experiment, which verified the accuracy of 2D DDA-SPH method in simulating solid-fluid interaction dynamic problems. Secondly, taking the Yonglian Tunnel as the research object, we simulated the water inrush disaster in the F2 fault of Yonglian Tunnel under the condition of different thickness of water-resistant rock mass. Based on the results of the simulation, the critical thickness of water-resistant rock mass was determined, which was about 5m. Lastly, we analyzed the process of the water inrush disasters based on the movement state of the fluid near the water-resistant rock mass. And we divided the process of the water inrush disasters in the jointed rock mass into three stage, which were mutation stage, cataclysmic stage and stable stage, which provided a theoretical basis for the prevention and control of water inrush in jointed rock tunnel.

Fluctuation analysis in the dynamic characteristics of continental glacier based on Full-Stokes model

Ice thickness has a great influence on glacial movement and ablation. Over the course of the change in thickness, area and external climate, the dynamic process of how glaciers change and whether a glacier’s changes in melting tend to be stable or irregular is a problem that needs to be studied in depth. In our study, the changes in the dynamic process of the No. 8 Glacier in Hei Valley (H8) under the conditions of different thicknesses in 1969 and 2009 were simulated based on the Full-Stokes code Elmer/Ice (http://www.csc.fi/elmer/). The results were as follows: (1) The thickness reduction in glaciers would lead to a decrease in ice surface tension and basal pressure and friction at the bottom, and the resulting extensional and compressional flow played an important role in the variations in glacial velocity. (2) The force at the bottom of the glacier was key to maintaining the overall stress balance, and the glaciers that often melted and collapsed in bedrock were more easily destroyed by the overall force balance and increased change rate of glacial thaw. (3) Temperature changes at different altitudes affected the ice viscous force. The closer the ice surface temperature was to the melting point, the greater the influence of temperature changes on the ice viscous force and ice surface velocity. Finally, we used the RCP 4.8 and 8.5 climate models to simulate the changes in H8 over the next 40 years. The results showed that with some decreases in ice surface compression and tension, the gravity component changes caused by local topography begin to control the ice flow movement on the surface of glacier, and melting of the glacial surface will appear as an irregular change. The simulation results further confirmed that the fluctuation in glacial dynamic characteristics could be attributed to the change in the gravity component caused by ablation.

Investigation of surface plasmons in Kretschmann structure loaded with a silver nano-cube

A composite structure based on a Kretschmann structure loaded with silver nano-cube is proposed. A 442-nm laser was used to excite surface plasmons in the composite structure, and the electric field enhancement was numerically simulated using the finite element method. The excitation angles of surface plasmons under conditions of different thicknesses of a PMMA film were obtained by studying the reflection spectrum of the Kretschmann structure. By examining the extinction spectra of silver nano-cubes of different sizes, its optimal size was selected, which is 70 nm. The electric field enhancement factors of the composite structure and the composite PMMA-spaced silver nano-cube and silver film structure were compared in detail. The results show that the coupling of localized surface plasmons and propagating surface plasmons produced by the proposed composite structure mean that its electric field enhancement factor is significantly greater. Moreover, the electric field enhancement factor can be further improved by adding another laser to irradiate the composite structure symmetrically. The high electric field enhancement generated by the composite structure indicates that it has considerable application prospects in surface-enhanced Raman scattering.

A Study of the Insulation Mechanism and Anti-Frost Heave Effects of Polystyrene Boards in Seasonal Frozen Soil

The damages resulting from frost heaving are the main causes of channel destruction in seasonal frozen soil regions. Over the years, many experimental studies have been performed regarding the channel anti-frost heaving in the Hetao irrigation area. However, there have been few experimental research studies conducted regarding the insulation and anti-frost heave effects of polystyrene boards (EPS) of different thicknesses. Therefore, in order to explore the insulation mechanism and anti-frost heave effects of precast EPS laid under the conditions of different thicknesses, an anti-frost heave test field was established in the Hetao irrigation area for the examination of the ground temperatures, frozen depths, frost heave amounts, and water content change rules. This study’s results showed that, for the laid EPS with thicknesses between 2 and 12 cm, the frost-heave reduction rate ranged from 53.2% to 92.6%; total accumulated temperature warming ranged from 248.65% to 565.93%; and the frozen depth reduction rate was between 59.8% and 75.9%. It was determined that the EPS per cm additions could effectively improve the ground temperatures at a buried depth of 30 cm by 0.78 °C, and reduce the frozen depth by 10.1 cm. Then, by comprehensively considering the positive economic and insulation effects, it was determined that the most appropriate thickness of the EPS laid under the precast concrete slabs in the Hetao irrigation area of Inner Mongolia was 8–10 cm.

Numerical Simulation Study on Optimization of Solar Flat-Plate Collector

Solar flat-plate collector is an important component in solar-thermal system, and its optimization is critical for the efficiency of energy utilization. In this paper, a comparative study on the thermal performance of solar flat-plate collector was carried out by numerical simulation under the conditions of different thicknesses and materials of absorber plate. The results show that the increase of absorber plate thickness contributes to restraining convection loss. The collector efficiency levels off when the absorber plate thickness reaches a certain value. In considering thermal performance and production cost, aluminum is an optimal material for absorber plate.

Heat Storage Performance Analysis of Solar Chimney Power Plant System

Solar chimney power plant which can realize continuous power generation is a potential power generation technology. Based on the heat transfer theory and hydrodynamics theory, a comprehensive heat transfer and flow model of solar chimney power plant was proposed, and the characteristics of unsteady temperature field and flow field of the system were analyzed. With Manzanares solar chimney power plant as the geometric prototype, the performance of plant generation output and generation stability were studied in condition of different thickness of heat storage layer, different specific heat capacity and thermal conductivity of heat storage medium. The numerical stimulation results showed that above three factors significantly affected the power generation output and generation stability. Thus, the optimization of the three factors was achieved in this paper, which provides the basis for the solar chimney heat storage system design.

Analysis for Floor Slabs of Wall-Slab System

The structure of Wall-slab is composed of slab and shear wall, and only in the outer wall part are the shear wall connected by a coupling beam. The floor and shear wall can bear vertical force and horizontal lateral force together. While under the situation of irregular bearing form shear wall and irregular partition loads, tablet computing becomes an urgent problem. Aiming at this problem, the model which is one layer of floor of Wall system has been used for analysis through the Safe software. In the condition of different thickness of slabs, exploratory results can get about the slab deformations, stresses and reinforcement ratios. The paragraph provides the basis to determine the optimal thickness of plate.

Experimental study to evaluate short-term deflections for two-way RC slabs

Determination of deflection in structure is important from serviceability criteria. Codal provisions are available to calculate deflections in RC members in general. The codal provisions for calculation of short-term deflection in RC two-way slab are based on the effective moment of inertia (Ieff), The Ieff depends on the cracking moment (Mr) and maximum moment due to service load (M). Short-term deflections determined based on the provision for two-way RC slabs, are not comparable with experimental values. Even sometime negative deflection is obtained with the procedure. Present paper gives a method designated as Equivalent Load Method, in which equivalent load is calculated using Grashoff-Rankine formulae, and is considered to be acting on the slab. The deflection calculated using equivalent load method is found to be closer to experimental values. The negative deflection has been tackled in literature by applying a factor of 0.7 to cracking moment (Mr). The deflection thus calculated again differs considerably with the experimental values. In the paper, with the method, a procedure has been proposed in which instead of the factor 0.7 being applied to Mcr; cracking moment of inertia is proposed to be used in place of effective moment of inertia. The deflection thus calculated has been found to be comparable with experimental results. Experimental data obtained and data available in literature have been used to validate the procedure. Experimental work has been carried out for two end conditions i.e. fixed supported and simply supported two-way RC slab. Six separate specimens were casted for both end condition of different thickness, sizes and for different loads.

Re-reddening on Strip Surface After Water Cooling

After water cooling, there is a big temperature difference between the center and the surface of strip, which leads to the heat transfer from the center to the surface, and the surface temperature can rise in a short time. The finite element method was used to simulate the phenomena of re-reddening on the surface of strip and to analyze the temperature field of hot rolled strip during laminar cooling, and the periodical variation curve of the cooling rate was obtained during water cooling and subsequent re-reddening. The results show that the critical line of the cooling rate is at 1/3 of the half-thickness from the strip surface. The regression model of the relation of re-reddening temperature, time, and distance from the surface was obtained in the re-reddening region. Re-reddening regularity on the surface of strip under the condition of different thickness and cooling rate was also studied.

Studies on pressure distribution in compression of block between parallel plates

Compression tests of a block between parallel plates are usually applied to determine the stress-strain curves in compression under plane-strain condition such as in rolling, and to estimate the "reduction capacity" of lubricants.It is clear that these tests are based on the compression under plane-strain condition. However, it will be necessary to confirm whether the compressive deformation of a block between parallel plates occurs under the plane-strain condition.The pressure distribution in the contact area between the material and the parallel plates was studied by the method of "pressure pick-up pin" under various conditions of different thicknesses of specimens, lubricants, reduction percentages, and thickness ratios (b/t0).The results obtained were summarized as follows:(1) When the thickness ratio (b/t0) was a positive integer, the value of specific yielding point stress (po/2k) was approximate to 1.(2) The pattern of contact pressure distribution in the direction of die width did not much depend upon lubricant conditions, thickness ratio, and reduction percentage. However, high pressure appeared in the middle part and near the ends of the die width, and lower pressure appeared in the intermediate parts.(3) As for the contact pressure distribution in the direction of larger length of die, the pressure showed maximum in its center and gradually decreased toward ends (plotting a convex curve) under good lubrication. Whereas, in bad lubrication, the maximum pressure appeared at several mm apart from the center, which plotted a concave curve.(4) When a block, having the same width as the die, was compressed between parallel plates, the pressure distribution along the larger length of die was nearly constant, which was called "flat pattern".(5) The leading factor affecting the pressure distributions in the compression of a block between parallel plates was the non-contact deformed part on both sides of the contact part between the die and specimen. The above part constrained the flow of material in the directions of width and length, and produced various patterns of pressure distribution.