Algorithm Selection Method Based on Coupling Strength for Partitioned Analysis of Structure-Piezoelectric-Circuit Coupling

In this study, we propose an algorithm selection method based on coupling strength for the partitioned analysis ofstructure-piezoelectric-circuit coupling, which includes two types of coupling or inverse and direct piezoelectriccoupling and direct piezoelectric and circuit coupling. In the proposed method, implicit and explicit formulationsare used for strong and weak coupling, respectively. Three feasible partitioned algorithms are generated, namely(1) a strongly coupled algorithm that uses a fully implicit formulation for both types of coupling, (2) a weaklycoupled algorithm that uses a fully explicit formulation for both types of coupling, and (3) a partially stronglycoupled and partially weakly coupled algorithm that uses an implicit formulation and an explicit formulation forthe two types of coupling, respectively.Numerical examples using a piezoelectric energy harvester,which is a typicalstructure-piezoelectric-circuit coupling problem, demonstrate that the proposed method selects the most costeffectivealgorithm.

Anisotropic strength,deformation and failure of gneiss granite under high stress and temperature coupled true triaxial compression

The anisotropic mechanical behavior of rocks under high-stress and high-temperature coupled conditions is crucial for analyzing the stability of surrounding rocks in deep underground engineering.This paper is devoted to studying the anisotropic strength,deformation and failure behavior of gneiss granite from the deep boreholes of a railway tunnel that suffers from high tectonic stress and ground temperature in the eastern tectonic knot in the Tibet Plateau.High-temperature true triaxial compression tests are performed on the samples using a self-developed testing device with five different loading directions and three temperature values that are representative of the geological conditions of the deep underground tunnels in the region.Effect of temperature and loading direction on the strength,elastic modulus,Poisson’s ratio,and failure mode are analyzed.The method for quantitative identification of anisotropic failure is also proposed.The anisotropic mechanical behaviors of the gneiss granite are very sensitive to the changes in loading direction and temperature under true triaxial compression,and the high temperature seems to weaken the inherent anisotropy and stress-induced deformation anisotropy.The strength and deformation show obvious thermal degradation at 200℃due to the weakening of friction between failure surfaces and the transition of the failure pattern in rock grains.In the range of 25℃ 200℃,the failure is mainly governed by the loading direction due to the inherent anisotropy.This study is helpful to the in-depth understanding of the thermal-mechanical behavior of anisotropic rocks in deep underground projects.

Coupling Strength and System Size Induce Firing Activity of Globally Coupled Neural Network

We investigate how firing activity of globally coupled neural network depends on the coupling strength C and system size N. Network elements are described by space-clamped FitzHugh- Nagumo （SCFHN） neurons with the values of parameters at which no firing activity occurs. It is found that for a given appropriate coupling strength, there is an intermediate range of system size where the firing activity of globally coupled SCFHN neural network is induced and enhanced. On the other hand, for a given intermediate system size level, there exists an optimal value of coupling strength such that the intensity of firing activity reaches its maximum. These phenomena imply that the coupling strength and system size play a vital role in firing activity of neural network.

Periodic synchronization of community networks with non-identical nodes uncertain parameters and adaptive coupling strength

In this paper, we propose a novel approach for simultaneously identifying unknown parameters and synchronizing time-delayed complex community networks with nonidentical nodes. Based on the LaSalle＇s invariance principle, a cri- teflon is established by constructing an effective control identification scheme and adjusting automatically the adaptive coupling strength. The proposed control law is applied to a complex community network which is periodically synchro- nized with different chaotic states. Numerical simulations are conducted to demonstrate the feasibility of the proposed method.

Temperature-dependent interlayer exchange coupling strength in synthetic antiferromagnetic [Pt/Co]_2/Ru/[Co/Pt]_4 multilayers

In this work, we experimentally investigated the thermal stability of the interlayer exchange coupling field(Hex) and strength(-Jiec) in synthetic antiferromagnetic(SAF) structure of [Pt(0.6)/Co(0.6)]2/Ru(tRu)/[Co(0.6)/Pt(0.6)]4multilayers with perpendicular anisotropy. Depending on the thickness of the spacing ruthenium(Ru) layer, the observed interlayer exchange coupling can be either ferromagnetic or antiferromagnetic. The Hexwere studied by measuring the magnetization hysteresis loops in the temperature range from 100 K to 700 K as well as the theoretical calculation of the-Jiec. It is found that the interlayer coupling in the multilayers is very sensitive to the thickness of Ru and temperature. The Hexexhibits either a linear or a non-linear dependence on the temperature for different thickness of Ru. Furthermore, our SAF multilayers show a high thermal stability even up to 600 K(Hex= 3.19 kOe,-Jiec= 1.97 erg/cm~2 for tRu=0.6 nm, the unit 1 Oe = 79.5775 A·m-1), which was higher than the previous studies.

Coupling strength effect on shot noise in boron devices

The shot noise properties in boron devices are investigated with a tight-binding model and the non-equilibrium Green＇s function. It is found that the shot noise and Fano factors can be tuned by changing the structures, the size, and the coupling strength. The shot noise is suppressed momentarily as we switch on the bias voltage, and the electron correlation is significant. The Fano factors are more sensitive to the ribbon width than to the ribbon length in the full coupling context. In the weak-coupling context, the Fano factors are almost invariant with the increase of length and width over a wide bias range.

CHARACTERISTICS OF STRENGTH CONTROL OF ADAPTIVE STRUCTURE WITH ELECTROMECHANICAL COUPLING

Based on the programming method, an electromechanical coupling adaptive statically indeterminate truss structure is controlled for increasing its load capacity. Several main parameters during the process of design of the adaptive structure are selected for a study of its characteristic during the control stage. The curves of each parameter for the effect of control results are plotted and corresponding conclusions are drawn. Thus, the theoretical basis is presented for optimal design, manufacture and control of the adaptive structure.

Magnetic-Field Dependence of Raman Coupling Strength in Ultracold ^(40)K Atomic Fermi Gas

We experimentally demonstrate the relation of Raman coupling strength with the external bias magnetic field in degenerate Fermi gas of 40K atoms. Two Raman lasers couple two Zeeman energy levels, whose energy splitting depends on the external bias magnetic field. The Raman coupling strength is determined by measuring the Rabi oscillation frequency. The characteristics of the Rabi oscillation is to be damped after several periods due to Fermi atoms in different momentum states oscillating with different Rabi frequencies. The experimental results show that the Raman coupling strength will decrease as the external bias magnetic field increases, which is in good agreement with the theoretical prediction.

Variable Coupling Strength of Silicene on Ag(lll)

We perform a scanning tunneling microscopy and spectroscopy study on the electronic structures of √3×√3- silicene on Ag（111）. It is found that the coupling strength of √3×√3-silicene with the Ag-（111） substrate is variable in different regions, giving rise to notable effects in experiments. This evidence of decoupling or variable interaction of silicene with the substrate is helpful to in-depth understanding of the structure and clectronic properties of silieene.

Couple analysis on strength reduction theory and rheological mechanism for slope stability

Considering the rheological properties of rock and soil body,and exploiting the merit of strength reduction technique,a theory of couple analysis is brought forward on the basis of strength reduction theory and rheological properties.Then,the concept and the calculation procedure of the safety factor are established at different time.Making use of finite element software ANSYS,the most dangerous sliding surface of the slope can be obtained through the strength reduction technique.According to the dynamic safety factor based on rheological mechanism,a good forecasting could be presented to prevent and cure the landslide.The result shows that the couple analysis reveals the process of the slope failure with the time and the important influence on the long-term stability due to the rheological parameters.

Influence of alkali metal doping on surface properties and catalytic activity/selectivity of CaO catalysts in oxidative coupling of methane

Surface properties （viz. surface area, basicity/base strength distribution, and crystal phases） of alkali metal doped CaO （alkali metal/Ca= 0.1 and 0.4） catalysts and their catalytic activity/selectivity in oxidative coupling of methane （OCM） to higher hydrocarbons at different reaction conditions （viz. temperature, 700 and 750 ℃; CH4/O2 ratio, 4.0 and 8.0 and space velocity, 5140-20550 cm^3 ·g^-1·h^-1） have been investigated. The influence of catalyst calcination temperature on the activity/selectivity has also been investigated. The surface properties （viz. surface area, basicity/base strength distribution） and catalytic activity/selectivity of the alkali metal doped CaO catalysts are strongly influenced by the alkali metal promoter and its concentration in the alkali metal doped CaO catalysts. An addition of alkali metal promoter to CaO results in a large decrease in the surface area but a large increase in the surface basicity （strong basic sites） and the C2＋ selectivity and yield of the catalysts in the OCM process. The activity and selectivity are strongly influenced by the catalyst calcination temperature. No direct relationship between surface basicity and catalytic activity/selectivity has been observed. Among the alkali metal doped CaO catalysts, Na-CaO （Na/Ca = 0.1, before calcination） catalyst （calcined at 750 ℃）, showed best performance （C2＋ selectivity of 68.8% with 24.7% methane conversion）, whereas the poorest performance was shown by the Rb-CaO catalyst in the OCM process.

Coupled Eulerian-Lagrangian simulation of a modified direct shearapparatus for the measurement of residual shear strengths

The simulation of large-strain geotechnical laboratory tests with conventional Lagrangian finite element method(FEM)techniques is often problematic due to excessive mesh distortion.The multiple reversal direct shear(MRDS)test can be used to measure the residual shear strength of soils in a laboratory setting.However,modelling and simulation generally require advanced numerical methods to accommodate the large shear strains concentrated in the shear plane.In reality,when the standard direct shear(DS)apparatus is used,the MRDS method is prone to two major sources of measurement error:load cap tilting and specimen loss.These sources of error make it difficult or even impossible to correctly determine the residual shear strength.This paper presents a modified DS apparatus and multi-reversal multi-stage test method,simulated using the coupled Eulerian-Lagrangian(CEL)method in a finite element environment.The method was successful in evaluating equipment and preventing both load cap tilting and specimen loss,while modelling large-deformation behaviour that is not readily simulated with the conventional FEM or arbitrary Lagrangian-Eulerian(ALE)analysis.Thereafter,a modified DS apparatus was created for the purpose of analysing mixtures of organic materials found in an Australian clay.The results obtained from the modified DS CEL model in combination with laboratory tests show a great improvement in the measured residual shear strength profiles compared to those from the standard apparatus.The modified DS setup ensures that accurate material residual shear strengths are calculated,a factor that is vital to ensure appropriate soil behaviour is simulated for numerical analyses of large-scale geotechnical projects.

Shear behavior of intact granite under thermo-mechanical coupling and three-dimensional morphology of shear-formed fractures

The shear failure of intact rock under thermo-mechanical(TM)coupling conditions is common,such as in enhanced geothermal mining and deep mine construction.Under the effect of a continuous engineering disturbance,shear-formed fractures are prone to secondary instability,posing a severe threat to deep engineering.Although numerous studies regarding three-dimensional(3D)morphologies of fracture surfaces have been conducted,the understanding of shear-formed fractures under TM coupling conditions is limited.In this study,direct shear tests of intact granite under various TM coupling conditions were conducted,followed by 3D laser scanning tests of shear-formed fractures.Test results demonstrated that the peak shear strength of intact granite is positively correlated with the normal stress,whereas it is negatively correlated with the temperature.The internal friction angle and cohesion of intact granite significantly decrease with an increase in the temperature.The anisotropy,roughness value,and height of the asperities on the fracture surfaces are reduced as the normal stress increases,whereas their variation trends are the opposite as the temperature increases.The macroscopic failure mode of intact granite under TM coupling conditions is dominated by mixed tensileeshear and shear failures.As the normal stress increases,intragranular fractures are developed ranging from a local to a global distribution,and the macroscopic failure mode of intact granite changes from mixed tensileeshear to shear failure.Finally,3D morphological characteristics of the asperities on the shear-formed fracture surfaces were analyzed,and a quadrangular pyramid conceptual model representing these asperities was proposed and sufficiently verified.

Chemo-mechanical couplings in compacted argillite submitted to high-pH environment

In the French concept of deep nuclear wastes repository, the galleries should be backfilled with excavated argillite after the site exploitation period. After several thousands of years, the degradation of the concrete lining of the galleries will generate alkaline fluid (pH 】 12) that will diffuse through the backfill. The objective of the paper is to describe the influence of such solute diffusion on the microstructure and the mechanical behavior of compacted argillite. Saturated-portlandite water was circulated through compacted samples for 3, 6 and 12 months at 20 °C or 60 °C, respectively. The microstructures before and after fluid circulation were determined with mercury intrusion porosimetry. Since it was planned to introduce additives (bentonite or lime) in the remoulded argillite to backfill the deep galleries, such mixtures were also studied. The results show that the influence of the alkaline fluid on the properties of the argillite is a function of the nature of the additive. The pure argillite undergoes slight modifications that can be related to a limited dissolution of its clayey particles. Conversely, intense alteration of the bentonite-argillite mixture was observed. Lime addition improves the mechanical characteristics of the argillite through the precipitation of cementitious compounds.

Inductively Coupling Plasma(ICP) Treatment of Propylene(PP) Surface and Adhesion Improvement

Study on increasing the roughness of the polymer substrate surface to enhance the adhesion with the copper layer in an inductively coupling plasma （ICP） process was carried out. The microstructure of the polymer substrate surfaces, which were exposed to different kinds of plasma treatment, was identified by scanning electron microscopy（SEM） analysis, peel strength of the copper coating and water surface contact angle. The adhesion of the substrate was largely enhanced by plasma treatment and the copper deposited coating reached a value of 7.68 kgf/m in verifying the adhesion of the copper coating with polymer material. The quality of the line/space 50/50 μm produced in the laboratory was examined by the pressure cooker test and proved to meet the requirement.

TENSILE-SHEAR STRENGTH AND BREAKING MORPHOLOGY FOR VIBRATION DAMPING LAMINATED STEEL SHEET

The phenolic resin-chloroprene nthher was used for sandwich in manufueturing the vibra-tion damping laminated steel sheet (also calied laminated sheet), Il is a metal matrix com-posite. The tensie-shear tests have been conducted over a range of temperatures from 20C to 150C and at the strain rates from 1.67× 10 ^(5) to 1.67× 10^(-2)s^(-1). The results show that test temperature will significaiilly affect the tensile shear strength of laminated sheet. and a minimal strength and a minimal activation energy occur near 80C . The tensile-shear breaking morphology of laminated sheet varies with strain rate and test temjteralurc.

Coupling effects of morphology and inner pore distribution on the mechanical response of calcareous sand particles

Calcareous sand is typically known as a problematic marine sediment because of its diverse morphology and complex inner pore structure.However,the coupling effects of morphology and inner pores on the mechanical properties of calcareous sand particles have rarely been investigated and understood.In this study,apparent contours and internal pore distributions of calcareous sand particles were obtained by three-dimensional(3D)scanning imaging and X-ray micro-computed tomography(X-mCT),respectively.It was revealed that calcareous sand particles with different outer morphologies have different porosities and inner pore distributions because of their original sources and particle transport processes.In addition,a total of 120 photo-related compression tests and 4923D discrete element simulations of four specific shaped particles,i.e.bulky,angular,dendritic and flaky,with variations in the inner pore distribution were conducted.The macroscopic particle strength and Weibull modulus obtained from the physical tests are not positively correlated with the porosity or regularity in shape,indicating the existence of coupling effect of particle shape and pore distribution.The shape effect on the particle strength first increases with the porosity and then decreases.The particle crushing of relatively regular particles is governed by the porosity,but that of extremely irregular particles is governed by the particle shape.The particle strength increases with the uniformity of the pore distribution.Particle fragmentation is mainly dependant on tensile bond strength,and the degree of tensile failure is considerably impacted by the particle shape but limited by the pore distribution.

Strength Optimization and Prediction of Cemented Tailings Backfill Under Multi-Factor Coupling

In order to solve the problem of strength instability of cemented tailings backfill(CTB)under low temperature environment(≤20℃),the strength optimization and prediction of CTB under the influence of multiple factors were carried out.The response surface method(RSM)was used to design the experiment to analyze the development law of backfill strength under the coupling effect of curing temperature,sand-cement ratio and slurry mass fraction,and to optimize the mix proportion;the artificial neural network algorithm(ANN)and particle swarm optimization algorithm(PSO)were used to build the prediction model of backfill strength.According to the experimental results of RSM,the optimal mix proportion under different curing temperatures was obtained.When the curing temperature is 10-15℃,the best mix proportion of sand-cement ratio is 9,and the slurry mass fraction is 71%;when the curing temperature is 15-20℃,the best mix proportion of sand-cement ratio is 8,and the slurry mass fraction is 69%.The ANN-PSO intelligent model can accurately predict the strength of CTB,its mean relative estimation error value and correlation coefficient value are only 1.95%and 0.992,and the strength of CTB under different mix proportion can be predicted quickly and accurately by using this model.

Mechanical properties of rock under coupled static-dynamic loads

Rock drilling machine,INSTRON testing system,and SHPB device are updated to investigate the characteristics of rocks at great depth,with high loads from overburden,tectonic stresses and dynamic impacts due to blasting and boring.It is verified that these testing systems can be used to study the mechanical properties of rock material under coupled static and dynamic loading condition and give useful guidance for the deep mining and underground cavern excavation.Various tests to determine the rock strength,fragmentation behavior,and energy absorption were conducted using the updated testing systems.It is shown that under coupled static-dynamic loads,if the axial prestress is lower than its elastic limit,the rock strength is higher than the individual static or dynamic strength.At the same axial prestress,rock strength under coupled loads rises with the increasing strain rates.Under coupled static and dynamic loads,rock is observed to fail with tensile mode.While shear failure may exist if axial prestress is high enough.In addition,it is shown that the percentage of small particles increases with the increasing axial prestress and impact load based on the analysis of the particle-size distribution of fragments.It is also suggested that the energy absorption ratio of a specimen varies with coupled loads,and the maximum energy absorption ratio for a rock can be obtained with an appropriate combination of static and dynamic loads.

Seepage-stress coupled modeling for rainfall induced loess landslide

Although rainfall is rare on the Loess Plateau of western China, landslides occur frequently there in rainy season. Surveys report that landslide hazards always follow heavy rains. In this study, a seepage-stress coupling model for rainfall induced landslide is used to examine an actual disastrous event in Yulin by the end of July, 2017. The effects of rainfall duration, rainfall intensity and soil weakening on slope stability are studied in detail. The results illustrate that the safety factor drops sharply at first and then is gradually declining to below 1.05 during additional two days of heavy rain. With soil strength softening considered, the slope would be more unstable, in which the weakening in soil cohesion is found to be a more sensitive factor.