scholarly journals Complex Variable Solution for Stress and Displacement of Layered Soil with Finite Thickness

2022 ◽  
Vol 12 (2) ◽  
pp. 766
Author(s):  
Xiangyu Sha ◽  
Aizhong Lu ◽  
Hui Cai ◽  
Chonglin Yin
Keyword(s):  
Finite Thickness ◽  
Soil Layer ◽  
Static Problem ◽  
Surface Settlement ◽  
Stress Fields ◽  
Research Subject ◽  
Analysis And Design ◽  
Complete Contact ◽  
Parametric Analyses ◽  
Good Agreement

The static problem of a layered isotropic elastic body is a very useful research subject in relation to the analysis and design of foundation works. Due to the complexity of the problem, there is no analytical solution to the problem so far. This study provides an efficient analytical approach to accurately calculate the displacement and stress fields of the soil. The constraints of bedrock on soil, different soil layer thickness and the shear stress of the foundation on soil were all taken into account in the analysis. In this study, each layer is regarded as an isotropic elastomer with infinite width, and the layers are in complete contact. By using conformal mapping, each layer is mapped to a unit circle, and the two complex potential functions are expanded into Taylor series with unknown coefficients. These unknown coefficients are obtained by satisfying boundary conditions and continuity conditions. The boundary and continuity conditions were verified in this paper. As a validation step, we compared the analytical results for the settlement with the results of the ANSYS numerical simulations and found good agreement. Parametric analyses were also carried out to investigate the influence of different distribution forms of base pressure on surface settlement, and the effects of layered properties on the surface settlement and stress field.

scholarly journals Method of Calculating the Compensation for Rectifying the Horizontal Displacement of Existing Tunnels by Grouting

2020 ◽  
Vol 11 (1) ◽  
pp. 40
Author(s):  
Yongjie Qi ◽  
Gang Wei ◽  
Feifan Feng ◽  
Jiaxuan Zhu
Keyword(s):  
Volume Expansion ◽  
Soil Layer ◽  
Horizontal Displacement ◽  
Soil Mass ◽  
Calculation Model ◽  
Additional Stress ◽  
Corrective Effect ◽  
Engineering Data ◽  
Subway Tunnels ◽  
Good Agreement

Sleeve valve pipe grouting, an effective method for reinforcing soil layers, is often employed to correct the deformation of subway tunnels. In order to study the effect of grouting on rectifying the displacement of existing tunnels, this paper proposes a mechanical model of the volume expansion of sleeve valve pipe grouting taking into consideration the volume expansion of the grouted soil mass. A formula for the additional stress on the soil layer caused by grouting was derived based on the principle of the mirror method. In addition, a formula for the horizontal displacement of a tunnel caused by grouting was developed through a calculation model of shearing dislocation and rigid body rotation. The results of the calculation method proposed herein were in good agreement with actual engineering data. In summary, enlarging the grouting volume within a reasonable range can effectively enhance the grouting corrective effect. Further, with an increase in the grouting distance, the influence of grouting gradually lessens. At a constant grouting length, setting the bottom of the grouting section at the same depth as the lower end of the tunnel can maximize the grouting corrective effect.

scholarly journals The substitution mechanism of Au in In-, Fe- and In-Fe-bearing synthetic crystals of sphalerite, based on the data from EPMA and LA-ICP-MS study

LITOSFERA ◽  
2019 ◽  
pp. 148-161 ◽  
Author(s):  
D. E. Tonkacheev ◽  
D. A. Chareev ◽  
V. D. Abramova ◽  
E. V. Kovalchuk ◽  
I. V. Vikentyev ◽  
...  
Keyword(s):  
Depositional Environments ◽  
Salt Flux ◽  
Research Subject ◽  
Trace Impurities ◽  
Valuable Component ◽  
Experimental Conditions ◽  
Icp Ms ◽  
Substitution Mechanism ◽  
Synthetic Crystals ◽  
Good Agreement

Research subject.Sphalerite (ZnS) is a widespread mineral that can be found in various depositional environments. During formation, this mineral can accumulate minor and trace impurities, with gold being one of the most valuable component. The issue of the chemical state of Au in sphalerite has been much discussed recently.Methods.Samples of In-, Fe- and In-Febearing sphalerite with a composition ranging from 0 to 2.5 mol.% In2S3 and 0 – 40 mol.% FeS were synthesized in an Ausaturated system using gas transport and salt flux techniques. The resulting products were subsequently investigated using EPMA and LA-ICP-MS.Results.All the elements under investigation are found to be homogeneously distributed within the sphalerite matrix. After quenching, sphalerite is shown to retain Au. Our data indicates that the observed increase in Au concentration is caused by the presence of In (up to 1.02 wt % Au) and, to a lesser extent, by that of Fe (up to ≈600 ppm Au). These elements substitute Zn in the crystal structure of sphalerite following the scheme Au+ + In3+(Fe3+) ↔ 2Zn2+, which is in good agreement with previous data obtained using the XAS method.Conclusions.A higher sulphur fugacity in the system leads to a more significant accumulation of Au in sphalerite. The concentration of Au in pure sphalerite does not exceed 10 ppm under our experimental conditions and does not depend on the activity of sulphur in the system.

Quarter mode rectangular cavity-based perfect metamaterial absorber in the terahertz region

2019 ◽  
Vol 33 (36) ◽  
pp. 1950460 ◽  
Author(s):  
Xiaojie Lu ◽  
Zhongyin Xiao ◽  
Mingming Chen
Keyword(s):  
Normal Incidence ◽  
Wave Theory ◽  
Metamaterial Absorber ◽  
Metal Plate ◽  
Rectangular Cavity ◽  
Perfect Absorption ◽  
Analysis And Design ◽  
Terahertz Region ◽  
Perfect Metamaterial Absorber ◽  
Good Agreement

In this work, we present the analysis and design of a perfect metamaterial absorber (MA) based on quarter mode rectangular cavity in the terahertz region. This structure is consisted of a metal plate where three different size quarter mode rectangular cavities are vertically placed on. Based on rectangular-cavity-theory, a formula is proposed to calculate the resonant frequency, which provides a guidance for designing MAs of such type. In terms of normal incidence, the simulated results show that the MA has three resonance points on 4.1301 THz, 4.6051 THz and 5.1088 THz, respectively, which is in good agreement with the calculated results. Furthermore, we present the distribution of E-field in the cavity and use the standing wave theory to explain the physical mechanism of the perfect absorption. These results verify the application of resonant cavities in the field of MA.

Analysis and design of inclined fractal defected ground-based circularly polarized antenna for CA-band applications

2020 ◽  
pp. 1-10
Author(s):  
Sonal Gupta ◽  
Shilpee Patil ◽  
Chhaya Dalela ◽  
Binod Kumar Kanaujia
Keyword(s):  
Ground Plane ◽  
Axial Ratio ◽  
Mobile Wimax ◽  
Impedance Bandwidth ◽  
Ieee 802.16E ◽  
Defected Ground Structure ◽  
Circularly Polarized ◽  
Analysis And Design ◽  
Centre Frequency ◽  
Good Agreement

Abstract Design of single-feed circularly polarized (CP) microstrip antenna is proposed in this article. The design employs the concept of E-shape patch with inclined fractal defected ground structure (IFDGS), which can improve the impedance bandwidth, gain, and axial ratio (AR) bandwidth. The excellent enhanced impedance bandwidth, axial ratio bandwidth, and gain are achieved by an inclined E-shaped fractal etched on the ground plane. The parameter studies of the E-shaped IFDGS are given to illustrate the way to obtain CP radiation. The third iterative IFDGS is fabricated on easily available FR4 substrate with a size of 0.494 λ0 × 0.494 λ0 × 0.019 λ0 (λ0 is the wavelength in free space at 3.624 GHz). The measured results verify the simulated results and show good agreement. The proposed antenna shows an impedance bandwidth of 12.7% at a centre frequency of 3.47 GHz and 3-dB AR bandwidth for this band is 2.39% at a centre frequency of 3.626 GHz. The measured peak gain for the proposed antenna is found as 8.1 dBi. The proposed antenna can be suitable for mobile WIMAX operation (IEEE 802.16e-2005 standard), wireless communication in CA-band and FCC.

Comparison between Pile-Up Singularities and Stress Fields Induced by Thin Slip Bands. Application to the Prediction of Grain Boundary Microcrack Nucleation

2013 ◽  
Vol 592-593 ◽  
pp. 61-66
Author(s):  
Maxime Sauzay ◽  
Mohamed Ould Moussa
Keyword(s):  
Slip Band ◽  
Tensile Deformation ◽  
Finite Thickness ◽  
Local Stress ◽  
Stress Fields ◽  
Stress Concentrations ◽  
Griffith Criterion ◽  
Slip Bands ◽  
Pile Up ◽  
Microcrack Initiation

Slip localization is widely observed in metallic polycrystals after tensile deformation, cyclic deformation or pre-irradiation followed by tensile deformation. Such strong deformation localized in thin slip bands induces local stress concentrations in the quasi-elastic matrix around, at the intersections between slip bands (SBs) and grain boundaries (GBs) where microcrack initiation is often observed. Since the work of Stroh, such stress fields have been mostly modeled using the dislocation pile-up theory which leads to stress singularities similar to the LEFM ones. The Griffith criterion has then been widely applied, leading usually to strong underestimations of the macroscopic stress to GB crack initiation. In fact, slip band thickness is finite: 20nm-1000nm depending on material, temperature and loading conditions. Then, many slip planes are plastically activated through the thickness, and not only one single atomic plane. To evaluate more realistic stress fields, numerous crystalline finite element (FE) computations have been carried out using microstructure inputs (slip band aspect ratio, crystal and GB orientation...). A strong influence of slip band thickness close to the slip band corner has been highlighted, which is not accounted for by the pile-up theory. But far away, the thickness has a negligible effect and the predicted stress fields are close to the one predicted by the pile-up theory. Closed-form expressions are deduced from the numerous FE computation results allowing a straightforward prediction of GB stress fields. Slip band plasticity parameters, such as length and thickness, as well as crystal orientation, GB plane and remote stress are taken into account. The dependence with respect to the various parameters can be understood in the framework of matching expansions usually applied to cracks with V notches of finite thickness. As the exponent of the GB stress close-field is only about one-half of the pile-up or LEFM crack one, the Griffith criterion may not be used for GB microcrack prediction in case of finite thickness. That is why finite crack fracture mechanics is used together with both energy and stress criteria. Taking into account SB finite thickness, t>0, leads to predicted remote stresses to GB microcrack initiation three to six times lower than the ones predicted using the to pile-up theory, in agreement with experimental data.

Quad Band Planar Inverted F Antenna for Smart Phone

2014 ◽  
Vol 573 ◽  
pp. 394-399
Author(s):  
R. Manikandan ◽  
P.K. Jawahar
Keyword(s):  
High Frequency ◽  
Smart Phone ◽  
Analysis And Design ◽  
High Frequency Structure Simulator ◽  
Low Profile ◽  
Resonance Frequencies ◽  
Theoretical Predictions ◽  
Communication Devices ◽  
Device Miniaturization ◽  
Good Agreement

In recent years, the demand for compact handheld communication devices has grown significantly. For device miniaturization antenna size is to be reduced. Micro strip and PIFA have been used for past few years. Since it has low profile geometry it can be embedded into devices. This project is to develop a Quad band small size Planar Inverted F Antenna (PIFA) for the operation in modern multi-band mobile transceiver system. Various techniques for analysis and design of such antenna investigated in this project. The design curve is used to design Quad band Planar inverted F Antenna to operate at the 900, 1800, 2100 and 3500 MHz bands. Since High Frequency Structure Simulator (HFSS) simulation result agrees well with the theoretical predictions, this project also designed through HFSS. An antenna designed at the four desired band and optimized to adjust the four resonance frequencies using HFSS simulation. The substrate FR4 (εr=4.4 & tanδ = 0.02) are in good agreement with the simulation result. Further bandwidth enhancements by making defects in the substrate at particular area were need of much reflection.

Research on Dynamic Characteristics of Large Span Transmission Tower in Icing Environment

2013 ◽  
Vol 756-759 ◽  
pp. 4262-4266 ◽  
Author(s):  
Yue Du ◽  
Lan Jiang ◽  
Yu Xin Zhou ◽  
Qiao Rong Li ◽  
Tai Ran Wan ◽  
...  
Keyword(s):  
High Altitude ◽  
Dynamic Characteristics ◽  
Weather Conditions ◽  
Research Subject ◽  
Transmission Tower ◽  
Analysis And Design ◽  
Large Span ◽  
Long Span ◽  
Tower Structure ◽  
High Altitude Area

The transmission tower with a big span in the freezing area is very sensitive to climate. When extreme weather approaches, the tower may collapse easily. The dynamic characteristics of transmission tower structure vary under different weather conditions. This paper, taking a 500kV long span tangent tower as the research subject, will demonstrate the dynamic characteristics of such structures when the weight of wires, the icing stiffness of tower structure and the thickness of ice are considered. The results show that icing has a great impact on the dynamic characteristics of the tower structure and it can not be neglected. When the ice is thick, the contribution of icing to the stiffness of the structure should be considered. This conclusion can provide a reference for the analysis and design of similar towers in high altitude area.

scholarly journals Closing the Energy Balance using a Canopy Heat Capacity – A physically based Approach for the Land Component JSBACHv3.11

2018 ◽  
Author(s):  
Marvin Heidkamp ◽  
Andreas Chlond ◽  
Felix Ament
Keyword(s):  
Heat Capacity ◽  
Energy Balance ◽  
Diurnal Cycle ◽  
Land Surface ◽  
Climate Models ◽  
Finite Thickness ◽  
Soil Layer ◽  
Surface Fluxes ◽  
Delayed Response ◽  
Stable Conditions

Abstract. Land surface-atmosphere interaction is one of the most important characteristic for understanding the terrestrial climate system, as it determines the exchange fluxes of energy and water between the land and the overlying air mass. In several current climate models, it is common practice to use an unphysical approach to close the surface energy balance within the uppermost soil layer with finite thickness and heat capacity. In this study, a different approach is investigated by means of a physical based estimation of the canopy heat capacity SkIn+. Therefore, in a first step, results of an offline simulation of the land component JSBACH of the MPI-ESM – constrained with atmospheric observations – are compared to energy- and water fluxes derived from eddy covariance measurements observed at the CASES-99 field experiment in Kansas where only shallow vegetation prevails. This comparison of energy and evapotranspiration fluxes with observations at the site-level provides an assessment of the model's capacity to correctly reproduce the coupling between the land and the atmosphere throughout the diurnal cycle. In a further step, a global coupled land-atmosphere experiment is performed using an AMIP type simulation over thirty years to evaluate the regional impact of the SkIn+ scheme on longer time scale, in particular, in respect to the effect of the canopy heat capacity. The results of the offline experiment show that SkIn+ leads to a warming during the day and to a cooling in the night relative to the old reference scheme, thereby improving the performance in the representation of the modeled surface fluxes on diurnal time scales. In particular: nocturnal heat releases unrealistically destroying the stable boundary layer disappear and phase errors are removed. On the global scale, for regions with no or low vegetation and a pronounced diurnal cycle, the nocturnal cooling prevails due to the fact that stable conditions at night maintain the delayed response in temperature, whereas the daytime turbulent exchange amplifies it. For the tropics and boreal forests as well as high latitudes, the scheme tends to warm the system.

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