椰子纤维研究利用及发展趋势

椰子纤维,数量多、价格便宜、综合性能优越,其研究和利用是一种变废为宝,利国利民的重大举措。本文对椰子纤维的学术研究及加工利用现状进行阐述,主要包括宏微观构造、解剖特征、化学成分分析和物理力学强度等,并介绍了椰子纤维在人造板和复合材料领域的利用现状。纵观椰子纤维利用全貌,椰子叶柄纤维至今未得到有效利用,如何对椰子各部位纤维有效利用,应成为今后学术研究及成果产业化的重点。

磺化加脂剂及塔拉栲胶在无铬皮革制造中的应用

就塔拉栲胶、磺化加脂剂在无铬鞣中,特别是植铝鞣的鞣制及以后工序对其所鞣革的影响作了一些研究,主要针对在工业上的应用。研究表明,塔拉栲胶鞣后的革呈土白色,Ts可以达到76℃,与铝鞣剂等其它鞣剂结合鞣后革的Ts明显提高,可以达到95℃以上。同时,鞣后的革的物理力学强度较高。适合于各种无铬鞣革的鞣制,特别是浅色甚至白色革的鞣制。另外,磺化加脂剂在无铬鞣中使用后,渗透性好,而且吸收性能好。

水泥稳定碎石基层抗裂机理的微观分析

本文结合润扬大桥南接线高速公路水泥稳定碎石基层的应用,通过水泥稳定碎石基层混合料微结构扫描电镜照片,初步比较研究了水泥稳定碎石基层混合料掺加粉煤灰、外加剂的物理力学强度形成机理,并就该基层抗裂机理进行了微观分析。

Effects of Freeze–thaw Cycles on Soil Mechanical and Physical Properties in the Qinghai–Tibet Plateau

Extreme freeze-thaw action occurs on the Qinghai-Tibet Plateau due to its unique climate resulting from high elevation and cold temperature.This action causes damage to the surface soil structure, as soil erosion in the Qinghai-Tibet Plateau is dominated by freeze-thaw erosion.In this research,freezing–thawing process of the soil samples collected from the Qinghai–Tibet Plateau was carried out by laboratory experiments to determinate the volume variation of soil as well as physical and mechanical properties, such as porosity, granularity and uniaxial compressive strength, after the soil experiences various freeze–thaw cycles.Results show that cohesion and uniaxial compressive strength decreased as the volume and porosity of the soil increased after experiencing various freeze–thaw cycles, especially in the first six freeze–thaw cycles.Consequently, the physical and mechanical properties of the soil were altered.However, granularity and internal friction angle did not vary significantly with an increase in the freeze–thaw cycle.The structural damage among soil particles due to frozen water expansion was the major cause of changes in soil mechanical behavior in the Qinghai–Tibet Plateau.

Variation of vertical and horizontal drilling rates depending on some rock properties in the marble quarries

The main objective of this study is to determine the rates of vertically and horizontally oriented drilling processes in marble quarries and to observe the factors affecting the drilling rates in terms of physical and mechanical properties of the rocks. In situ drilling tests were performed in different marble quarries with different marble types and drilling times and penetration rates for a series of successive depthincrements were trying to be determined under vertically and horizontally oriented conditions. In order to understand the relation between the parameters that are investigated within the scope of this research, uniaxial compressive strength, Brazilian tensile strength, impact strength, Bohme abrasion strength, P-wave velocity, porosity, unit volume weight, Schmidt hardness index and brittleness index values were correlated with the drilling rates. It was noticed that the porosity and unit volume weight could be taken as the key parameters among them for obtaining meaningful correlation with drilling performance. It was also observed that the physical and mechanical rock properties are more relevant in vertical drilling than horizontal drilling.

Implications of exergaming for the physical education curriculum in the 21st century

Exergaming provides an initial situationally interesting environment in physical education （PE） that serves to motivate novice players to engage in PE or physical activity. Current research suggests, however, that as students persist in this activity their situational interest decreases as their ability to exercise consistently at moderate intensity levels increases. In this article I will briefly review the literature citing benefits of exergaming and the role of exergaming in contemporary PE curricula before turning to the question of the place of exergaming in a learning- oriented approach to PE. I will suggest that exergaming, when taught within a situated learning framework, can contribute to student under- standing of the effects of exercise on their bodies and may produce meaningful lessons to assist students to create, monitor, and adapt a fitness plan to participate in life long exercise using a variety of physical activities. Copyright O 2013, Shanghai University of Sport. Production and hosting by Elsevier B.V. All rights reserved.

Experimental study on remodeling strength of granular materials under different loads and lengths of time

Remodeled clay and sand rock specimens were prepared by designing lateral confinement and water drainage experiments based on the stress exerted on granular materials in a waste dump.An in situ test was conducted in an internal waste dump;the physical and mechanical parameters of the remodeled rock mass dumped at different time and depths were measured.Based on statistics,regression analysis was performed with regard to the shearing stress parameters acquired from the two tests.Other factors,such as remodeling pressure(burial depth),remodeling time(amount of time since waste was dumped),and the corresponding functional relationship,were determined.Analysis indicates that the cohesion of the remodeled clay and its remodeling pressure are correlated by a quadratic function but are not correlated with remodeling time length.In situ experimental results indicate that the shear strength of reshaped granular materials in the internal dump is positively correlated with burial depth but poorly correlated with time length.Cohesion Cand burial depth H follow a quadratic function,specifically for a short time since waste has been dumped.As revealed by both in situ and laboratory experiments,the remodeling strength of granular materials varies in a certain pattern.The consistency of such materials verifies the reliability of the remodeling experimental program.

Experimental Study on the Use of Trass as a Supplementary Cementitious Material in Pervious Concrete

Abstract： The purpose of this paper is to evaluate the suitability of using trass as a supplementary cementing material in pervious concrete. OPC （Ordinary Portland Cement） was replaced in the concrete mix by 15%, 25% and 35% weight percentages and the results were compared with reference mixtures with 100% Portland cement. The variables in this study were trass content, aggregate size and water to cement ratio. Sixteen eases of concrete mixtures were tested to study physical and mechanical properties of hardened concrete, including porosity, permeability, compressive strength, splitting-tensile strength and flexural strength at various ages. Results indicated that mechanical properties of the pervious concrete marginally decreased with the increased content of trass when compared to the reference mixtures. However, at later ages the differences were insignificant.

Experimental study on similarity materials for soft rock of deep-buried tunnels

When every parameter is properly scaled down in accordance with some similarity coefficients, it is possible to study the physical-mechanical properties of rock mass with a scale model. To identify the key mechanisms of soft rock in deep buried tunnels, the proper sand, binder and ratio were selected. During the process, the model manufacture technology was introduced and typical tests were done and the results were presented. The physical and meehanieal properties effects caused by each composition were discussed. It is shown that the physical and mechanical properties of chosen ratio material such as uniaxial compressive strength tests, elasticity modulus, tensile strength, internal frictional angle, and Poisson＇s ratio meet with similarity relationship well. The physical and mechanical properties of deep soft rock are simulated successfully.