论篮球赛事心理抗压方法及良好心理品质的作用

篮球比赛是一种人与人对抗的运动项目。在有足够的体力情况下,还需要有强大心理承受能力。参加比赛的过程的当中,经常是心理的原因导致了整场比赛的失利。

天津厚地层超长钻孔灌注桩单桩承载特性研究

天津市某主塔楼桩基选用后压浆超长钻孔灌注桩,为了掌握超长后压浆钻孔灌注桩在该地层的工程特性,共设计了2组(共8根)试桩进行单桩竖向抗压静载试验。试桩中安装了振弦式钢筋计和分层沉降管以反映桩侧摩阻力和桩身分层沉降状态。对试验数据进行对比分析和计算结果表明,桩侧注浆可以明显提高超长桩的侧摩阻力;采用预压加载可以增强超长桩的弹性,减少桩顶的沉降;卸荷稳定后试桩具有桩侧阻力,桩身上段所受阻力为负摩阻力,下段为正摩阻力,同时具有的桩身轴力使试桩产生一定的压缩,其压缩量为残余变形量的重要组成部分。

Simulation of rock deformation and mechanical characteristics using clump parallel-bond models

To properly simulate hard rock with a high ratio of the uniaxial compressive strength to tensile strength(UCS/TS) and realistic strength-failure envelope,the rock deformation and mechanical characteristics were discussed in detail when the particle simulation method with the clump parallel-bond model(CPBM) was used to conduct a series of numerical experiments at the specimen scale.Meanwhile,the effects of the loading procedure and crack density on the mechanical behavior of a specimen,which was modeled by the particle simulation method with the CPBM,were investigated.The related numerical results have demonstrated that:1) The uniaxial compressive strength(UCS),tensile strength(TS) and elastic modulus are overestimated when the conventional loading procedure is used in the particle simulation method with the CPBM; 2) The elastic modulus,strength and UCS/TS decrease,while Poisson ratio increases with the increase of the crack density in the particle simulation method with the CPBM; 3) The particle simulation method with the CPBM can be used to reproduce a high value of UCS/TS(>10),as well as a high friction angle and reasonable cohesion strength; 4) As the confining pressure increases,both the peak strength of the simulated specimen and the number of microscopic cracks increase,but the ratio of tensile cracks number to shear cracks number decreases in the particle simulation method with the CPBM; 5) Compared with the conventional parallel-bond model,the CPBM can be used to reproduce more accurate results for simulating the rock deformation and mechanical characteristics.

A Novel Multichannel Audio Signal Compression Method Based on Tensor Representation and Decomposition

Multichannel audio signal is more difficult to be compressed than mono and stereo ones.A novel multichannel audio signal compression method based on tensor representation and decomposition is proposed in this paper.The multichannel audio is represented with 3-order tensor space and is decomposed into core tensor with three factor matrices in the way of channel,time and frequency.Only the truncated core tensor is transmitted which will be multiplied by the pre-trained factor matrices to reconstruct the original tensor space.Objective and subjective experiments have been done to show a very noticeable compression capability with an acceptable output quality.The novelty of the proposed compression method is that it enables both high compression capability and backward compatibility with limited signal distortion to the hearing.

Treatment of bauxite residue dust pollution by improving structural stability via application of synthetic and natural polymers

The residue drying area(RDA)is the major source of fugitive red sand(RS)dust emissions in the bauxite mining industry and causes serious environmental and safety detriments.Polymer stabilizer(PS)is one of the promising non-traditional stabilizers to mitigate such issues.This research investigated the unconfined compressive strength(UCS)of RS using synthetic polymer stabilizer(SPS)and natural polymer stabilizer(NPS),and to determine the optimum application concentration and mixing ratio of the PAM and Guar gum mixture.Results illustrated that PAM apparently outperform Guar gum in stabilizing sand particles.The mixture of PAM and Guar gum is more effective than individual use.The optimum polymer concentration and the mixing ratio are 0.94 wt.%and 0.6(PAM:total(PAM+Guar gum)),respectively.A rigorous regression model was developed to predict the UCS value based on application concentration and mixing ratio for the purpose of cost and time efficiency.

Experimental study on the compressive strength of grouted concrete block masonry based on nondestructive detection methods

Existing nondestructive detection methods were adopted to test the compressive strength of grouted concrete block masonry,i.e.the rebound method,pulling-out method and core drilling method were employed to test the strength of block,mortar and grouted concrete,respectively.The suitability of these methods for the testing of strength of grouted concrete block masonry was discussed,and the comprehensive strength of block masonry was appraised by combining existing nondestructive or micro-destructive detection methods.The nondestructive detection test on 25 grouted concrete block masonry specimens was carried out.Experimental results show that these methods mentioned above are applicable for the strength detection of grouted concrete block masonry.Moreover,the formulas of compressive strength,detection methods and proposals are given as well.

Compressive Strength Prediction of Porous Concrete Using Nondestructive Tests

This research focused on a prediction of compressive strength in porous concrete based on the ratio of air-entrained agents in the concrete slab using nondestructive testing methods such as the Impact Echo （IE） method, Spectral Analysis of Surface Wave （SASW） method and Free-Free Resonance （FFR） test. The method that best predicts the strength of the concrete slab can be derived from a relationship between compressive strengths and stress wave velocities. Concrete slab specimens of varying air content, were formed with a mix ratio of air-entrained agent of 0%, 0.15%, 0.3%, 0.7% and 1.5% by weight. These slabs were tested and analyzed to measure the stress wave velocities in order to develop a correlation with compressive strengths. The plot between the stress waves and compressive strengths showed a stiffslope up to an air ratio of 4% with a less steep slope beyond this point. In the process of predicting the compressive strength of concrete slab specimens, the prediction of compressive strength based on the compression wave velocity caused an average error of 4.9% in the compression wave velocity, and the prediction of compressive strength based on the surface wave velocity caused an average error of 2.2% in the surface wave velocity.

Concrete Containing Marginal Aggregates for Use in Concrete Pavement

The study presented an analysis accessing the feasibility of using concrete containing marginal aggregates in concrete pavement slabs. The physical properties of aggregates were first determined and concrete was produced from them. Marginal aggregates were found to have higher fines, absorption, soundness loss, micro-Deval abrasion loss, LA （Los Angeles） abrasion loss and lower specific gravity and unit weight when compared with standard aggregates. Workability of concrete containing marginal aggregate was found to be similar to concrete containing normal aggregates when Shilstone mix design method was used to optimize the concrete mixes. The compressive strength, splitting tensile, flexural strength and modulus of elasticity of concrete containing marginal aggregates were determined and found to be generally lower than concrete containing standard aggregates. A typical concrete pavement in Florida was modeled in FEACONSIV （finite element analysis of concrete slab） software developed at the University of Florida. Laboratory determined mechanical and thermal properties of concrete were inputted in FEACONS IV and analyzed for maximum induced stresses. Critical stress to strength ratios, i.e., ratio between maximum computed stresses obtained from FEACONS IV to modulus of rupture （strength） of concrete, was used as evaluation criterion for different concrete pavement mixes. It was found that, in general, concrete containing marginal aggregates have higher stress to strength ratios as compared with concrete containing standard aggregates.