Slip Resistance of Industrial Floor Surfaces: Development of an Elastomer Suited to In-Situ Measurement

Slips contribute to 12% of occupational accidents. A slip resistant floor is a mean to prevent slipping accidents occurring in workshops. Floor slip resistance is often evaluated by measuring a friction index, proportional to the force opposing slipping of a reference elastomer on the floor surface under test. When implementing a portable appliance, slip resistance measurements carried out on lubricated floors were not stabilized. The authors advanced the hypothesis of oil impregnating the elastomer. A new elastomer suited to in-situ measurement has been developed to achieve stable measuring conditions. This study highlights the fact that the nature and characteristics of a reference elastomer must be specified when slip resistance measurements are carried out.     

钢渣掺量对陶瓷地砖性能的影响

为了提高转炉钢渣质陶瓷地砖的性能,对其最佳配方进行了研究。利用转炉钢渣和滑石等常用建筑陶瓷原料,在没有特殊添加剂的情况下,经过模压成型制备了陶瓷地砖。通过X射线衍射和高倍电镜分析,研究了原料成分对转炉钢渣质陶瓷地砖结晶过程中的影响规律。结果表明,压制成的坯体最佳烧结温度为1220 ℃。转炉钢渣、滑石和高岭土在用量分别为45%、42%和13%时,原料中的CaO/MgO质量比在1.4附近,转炉钢渣质陶瓷的性能最佳。当转炉钢渣占陶瓷原料30%~70%时,钢渣中Fe2O3和Cr2O3可起到促进转炉钢渣陶瓷晶化成核时形成透辉石相和降低烧成温度的作用。本工作为转炉钢渣大规模资源化及综合利用奠定基础。     

地板送风系统室内可吸入颗粒物沉降特性的试验研究

分析地板送风系统停机后影响室内可吸入颗粒物浓度变化的因素,建立颗粒物浓度的沉降模型并求出分析解,得出颗粒物浓度随时间的变化规律.通过颗粒物浓度的沉降模型计算颗粒物的沉降损失率和沉降速度.结果表明,当室内颗粒物的粒径大于1 μm时,其沉降损失率与粒径呈线性正相关; 粒径小于1 μm时,其沉降损失率和衰减率低于前者,但沉降稳定后的颗粒物浓度远大于前者.研究进一步证明了大粒径颗粒物的沉降主要由重力决定而小粒径的由布朗扩散力决定.     

Air quality analysis and indexing of Kolkata city with respect to vertical floor heights and seasonal variation

Air pollution is one of the most important global environmental issues. Urban air quality is generally becoming vulnerable especially in the developing countries due to various developmental activities. Several national and international studies prove that air pollution is harmful to human health and its long term exposure contributes to even mortality. Current study has been designed to determine the vertical floor wise air quality status of the city of Kolkata and the seasonal variation of the pollutants during two consecutive years. Particulate matter (PM₁₀ and suspended particulate matter), oxides of nitrogen, sulfur dioxide and carbon monoxide were analyzed for a total number of 135 air quality samples throughout the study area and period. Pollutants were found positively correlated with each other and with the floor heights. According to the air quality indexing, all the places were found affected from moderate to severe air pollution irrespective of the vertical floor heights, seasons and places. Although, no such seasonal trend has been emerged from the study but the number of samples beyond standard is found highest during the winter season followed by pre-monsoon.     

Influences of canopy structure and physiological traits on flux partitioning between understory and overstory in an eastern Siberian boreal larch forest

Boreal forests play an important role in the global balance of energy and CO₂. Our previous study of elaborate eddy covariance observations in a Siberian boreal larch forest, conducted both above the forest canopy and at the forest floor, revealed a significant contribution of latent heat flux (LE) from the cowberry understory to the whole ecosystem LE. Thus, in the present study, we examined what factors control the partitioning of whole ecosystem LE and CO₂ flux into the understory and overstory vegetation, using detailed leaf-level physiology (for both understory and overstory vegetation) and soil respiration property measurements as well as a multilayer soil-vegetation-atmosphere transfer (SVAT) model. The modeling results showed that the larch overstory's leaf area index (LAI) and vertical profile of leaf photosynthetic capacity were major factors determining the flux partitioning in this boreal forest ecosystem. This is unlike other forest ecosystems that tend to have dense LAI. We concluded that control of the larch overstory's LAI had a relationship with both the coexistence of the larch with the cowberry understory and with the water resources available to the total forest ecosystem.     

不同切槽参数对围岩稳定性分析

为了分析切槽深度和宽度对巷道围岩变形的影响和确定最佳的底板切槽参数,通过理论分析底板破坏的特征和相应的支护措施;采用FLAC 3D模拟了在不同切槽条件下巷道围岩变形的影响规律;研究了在不同切槽参数条件下巷道围岩的变形情况。结果表明,底板岩层强度不同时应当采取不同的支护措施,底板岩层强度较低时适宜采用加固法,强度较高时采用卸压法。当采用底板切槽来降低巷道围岩变形量时,在底鼓量逐渐减少时顶板下沉量也在急剧增加,并且顶板下沉量要大于底鼓的减少量。因此采用切槽卸压降低底鼓量的方法适用于顶板比较稳定的岩层,在底板中部切槽的效果要优于在两底角切槽,切槽深度为巷道宽度一半时,巷道稳定性最好。     

软弱底板特厚煤层综放面矿压特征研究与应用

水帘洞煤矿3802工作面是彬长矿区首个采用8m小区段煤柱护巷、面临软弱底板问题的特厚煤层工作面,生产条件复杂,类似开采技术经验较少。针对此问题,采用岩石物理力学性质测试和计算机数值模拟等手段,明确软弱底板对综放面矿压影响机理;通过现场实测,对3802工作面矿压特征和覆岩移动规律等进行研究,结果表明,软弱底板条件下特厚煤层综放面较一般底板下特厚煤层综放面矿压显现特征不同,软弱底板吸收能量,将应力转移到深处,一定程度上消除了冲击地压危险,同时矿山压力显现平缓不明显,动载系数小。现场实测结果表明巷道围岩稳定,研究结果可以在类似条件下推广应用。     

不对称大底板多塔楼隔震结构的地震响应分析

针对不对称大底板多塔楼隔震结构体系,通过建立地震响应的动力分析简化模型,推导出不对称大底板多塔楼隔震结构体系地震作用下的运动方程。对一实际的不对称大底板多塔楼隔震结构进行地震响应仿真分析,探讨塔楼质量偏心率和塔楼质量比对结构周期比、位移比和层剪力比的影响。结果显示,不对称大底板多塔楼隔震结构扭转角主要由隔震层产生;与不隔震结构相比,不对称大底板多塔楼隔震体系的扭转角减小,可取得较好的减震效果;塔楼与底板的位置分布和质量分布会影响体系的扭转效应和减震效果,应尽量使塔楼的质心与底板质心重合,塔楼质量分布均匀,以减小结构的扭转效应,提高减震效果。     

Slip safety risk analysis of surface properties using the coefficients of friction of rocks

This study was conducted to determine the most appropriate surface processing techniques (SPT), environmental conditions (EC) and surface roughness (SR) to minimize the risk of slipping when pedestrians walk on a floor covering of rocks barefoot and with shoes. Coefficients of friction (COFs) and values of SR were found using five different types of rocks, four SPT and two (ramp and pendulum) tests. Results indicate that the parameters which affect the COF values of rocks include SR, EC and SPT. Simple linear regression was performed to examine the relationship between the values of the COF and the SR. The value of the COF was identified as R²?≥?0.864. Statistical results, which are based on experimental measurements, show that rocks are classified according to their safe use areas depending on their COF and SR values.     

我国城市人居环境改善与能源消费关系研究

随着我国经济建设水平和综合国力的提高,近20年来人居环境的改善有目共睹。但与此同时能源消耗和温室气体排放增加是个不容回避的问题。本文选择城市人均住宅建筑面积、人均拥有道路面积、人均公园绿地面积三个指标反映我国城市人居环境质量,研究了我国城市人居环境改善和能源消费之间的变化关系。通过与发达国家的对比,发现我国人居环境建设并没有像发达国家那样带来人均生活能源消费的同幅增长,而是出现了"喇叭口"现象,两个指标之间最大相差2.4倍,但也存在一个适度的节能居住条件,中国目前已经偏离了这个最优点并处于耗能的上升期。德国与我国类似,在户均住房面积和人均能源消费量之间也存在一种类似U型曲线关系,但上升阶段明显比我国更陡。虽然与德国、日本、美国相比我国在人均能源消费上最少,但从总量和长期趋势来看,中国仍面临着重重挑战,必须通过使用节能技术和新能源来降低能耗、减少二氧化碳排放,营造节能又宜居的城市人居环境。