巷(隧)道支护中的非对称荷载效应

针对对称结构的巷 (隧 )道支护体在非对称荷载作用下易于变形和破坏的特点 ,通过大量的现场观测 ,建立了该条件下巷 (隧 )道的“支护体—围岩”相互作用模型 ,引入非对称荷载因子和结构分析方法 ,研究了不同类型支护体在非对称荷载条件下的内力及变形性能 ,讨论了非对称荷载对支护体承载能力和可缩性能的影响 ,并据此给出了该条件下巷 (隧 )道支护体的设计要素。

特种支架在煤巷交岔点中的使用

矿井在深部煤层开采过程中 ,煤巷交岔点使用特种支架 ,会取得较好的技术、经济效益。

Reversible pre-excitation cardiomyopathy:a case report

This paper reported a 25-year-old hospitalized woman complained of recurrent chest tightness and dyspnea for 3 months.The electrocardiogram showed pre-excitation and the echocardiogram showed left ventricular wall contraction reduced diffusely and moved asynchronously.In the systolic period,the regional septum basal segment moved to the right ventricle like an aneurysm.In cardiac magnetic resonance imaging examination,there was no significant myocardial fibrosis.The patient further had an endomyocardial biopsy and pathological examination showed nonspecific changes,only with mild interstitial edema.After an electrophysiological study,the patient was finally diagnosed with pre-excitation cardiomyopathy with a right anteroseptal para-hisian manifest accessory pathway.Radiofrequency catheter ablation was then performed to block the advanced pathway.6 months after ablation,the left ventricular systolic function and synchrony improved significantly,and the symptoms were alleviated.

A CONSTITUTIVE EQUATION SATISFYING THE NULL CONDITION FOR NONLINEAR COMPRESSIBLE ELASTICITY

This paper constructs a polyconvex stored energy function, satisfying the null condition, for isotropic compressible elastic materials with given Lame constants. The difference between this stored energy function and St Venant-Kirchhoff's is a three order term.

Compressional behavior of MgCr_2O_4 spinel from first-principles simulation

The compressional behavior of the MgCr_2O_4 spinel has been investigated with the CASTEP code using density functional theory and planewave pseudopotential technique. We treated the exchange-correlation interaction by both the local density approximation（LDA） and generalized gradient approximation（GGA） with the Perdew-Burker-Ernzerhof functional. Our simulation was conducted for the pressure range of 0–19 GPa. We obtained the isothermal bulk modulus（K_T） of the MgCr_2O_4 spinel as 181.46（48） GPa（GGA; low boundary） or 216.1（11） GPa（LDA; high boundary）, with its first derivative（K＇_T） as 4.41（6） or 4.5（1）, respectively. The oxygen parameter u is not constant but negatively correlated with P, and decreases by about 0.5–0.6% for the investigated P range. The component polyhedra have different compressibilities, increasing in the order of（O_4）_1

Review of studies on structural performance of recycled aggregate concrete in China

This paper presents a review of the studies on the structural performance of recycled aggregate concrete(RAC) elements and structures in the past 10 years in China.The flexural and shear behaviour of RAC beams,the compression performance of RAC columns as well as the flexural performance of RAC slabs are overviewed and summarized.The seismic responses of beam-column joints,shear walls as well as frames made of RAC are also covered.The experimental observations indicate that the structural performance of RAC elements and structures is somewhat similar to that of natural aggregate concrete(NAC) members.A brief introduction to the application of RAC in sustainable buildings in China is also presented.

Simulation of non-Newtonian (Power-law) fluid flow past a row of square cylinders

The power-law fluid flow past a row of uniform placed square cylinders is investigated using the Lattice Boltzmann method (LBM).The flow is assumed to be two-dimensional and incompressible.The relaxation time is assumed to be shear-dependent and determined by using a variable parameter related to the local shear rate.The effects of both shear-thinning/shear-thickening property and the cylinder spacing on the confluence of the jets are mainly concerned.The bifurcation diagrams of the flow are obtained,which include confluences of double and quadruple jets.The results show that both the first and second pitchfork bifurcations are advanced due to the effect of the shear-thinning property,and postponed due to the shear-thickening property.

From liquid metal to stretchable electronics:Overcoming the surface tension

The field of stretchable electronics mainly includes electronic products conformal with tissues,being integrated into skin or clothing.Since these products need to work during deformation,their requirements for materials focus on stretchability and conductivity.Liquid metals are excellent materials with these properties.However,liquid metals have extremely high surface tension at room temperature,which will spontaneously form a spherical shape and are difficult to form the shape required by stretchable devices,which is the biggest obstacle to their development in this emerging field.Therefore,the emphasis is placed on the principle of overcoming the high surface tension in this review,and various methods of using liquid metals to fabricate stretchable electronic devices based on these principles have been linked.Liquid metals show promise in the convenience of sensing,energy harvesting,etc.The existing challenges and opportunities are also discussed here.

Asymptotic limit of the Gross-Pitaevskii equation with general initial data

This paper mainly concerns the mathematical justification of the asymptotic limit of the GrossPitaevskii equation with general initial data in the natural energy space over the whole space. We give a rigorous proof of the convergence of the velocity fields defined through the solutions of the Gross-Pitaevskii equation to the strong solution of the incompressible Euler equations. Furthermore, we also obtain the rates of the convergence.