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61.
为了反映岩质边坡在节理面注浆后的变形效应,首先,通过室内试验,分析注浆前后岩体变形和破坏的全过程,以探讨其抗剪性能(粘结力c和内摩擦角φ)的变化;然后,基于理想弹塑性本构模型的Mohr-Cou-lomb准则,运用拉格朗日元数值方法(FLAC3D),对岩坡注浆前后变形效应(水平位移、垂直位移、剪应变增量)进行模拟。结果表明:注浆加固后,岩体的位移场变得均匀和连续,节理面处的较大位移受到抑制,边坡的整体性得到提高,有利于边坡的稳定性。 相似文献
62.
H. Cornier-Ríos P. A. Sundaram J. T. Celorie 《Journal of Polymers and the Environment》2007,15(1):51-56
Recycled plastics are considered low performance materials because their properties are expected to decrease drastically with
recycling. The objective of this study was to characterize a 15 wt.% glass filled polyethylene terephthalate (rPET-15GF) using
six recycle generations and four recycle ratios. Mechanical properties such as tensile strength, elastic modulus, and percent
elongation to failure of the PET composite were determined for various recycle generations and recycle ratios. Results show
that the mechanical properties of rPET-15GF decrease slightly per recycle generation. In contrast, thermal properties of rPET-15GF
were not at all affected by the recycling process. This data demonstrates that recycled glass filled PET can be used effectively
to fabricate components without significantly affecting their mechanical performance. 相似文献
63.
64.
Wayne Turnberg Author Vitae William Daniell Author Vitae 《Journal of Safety Research》2008,39(6):563-568
Problem
Psychometrically validated measurement tools are needed to evaluate an organization's safety climate. In 2000, Gershon and colleagues published a new healthcare safety climate measurement tool to determine its relationship to safe work behavior (Gershon, R., Karkashian, C., Grosch, J., Murphy, L., Escamilla-Cejudo, A., Flanagan, P., et al. (2000). Hospital safety climate and its relationship with safe work practices and workplace exposure incidents. American Journal of Infection Control, 28, 211-21). The present study evaluated the psychometric properties of the Gershon tool when modified to address respiratory rather than bloodborne pathogen exposures.Method
Medical practitioners, nurses, and nurse aides (n = 460) were surveyed using the modified Gershon tool. Data were analyzed by factor analysis and psychometric properties of the tool evaluated.Results
Eight safety climate dimensions were extracted from 25 items (Cronbach's alpha range: 0.62 - 0.88). Factor extractions and psychometric properties were reasonably consistent with those of the Gershon tool.Impact on Industry
The Gershon safety climate tool appears to have sufficient reliability and validity for use by healthcare decision makers as an indicator of employee perceptions of safety in their institution. 相似文献65.
开展对典型可燃物燃烧烟尘的物化特性差异性研究,是全面了解烟尘信息的基础.基于可控条件下的燃烧试验,对典型可燃物燃烧烟尘物理特性和化学组分进行了分析.通过对比分析汽油燃烧烟尘、聚苯乙烯燃烧烟尘、ABS燃烧烟尘及柴油烟尘和正庚烷烟尘的透射电镜图片,对透射电镜图的紧凑性、复杂性及灰度值进行了深入分析,探讨了燃烧烟尘的物理差异性.利用固相微萃取-气质联用技术(SPME-GC-MS),对汽油燃烧烟尘、聚苯乙烯燃烧烟尘、ABS燃烧烟尘化学组分进行了分析和对比.通过燃烧烟尘的特征物质组分的分析,得到3种燃烧烟尘在特征物质的分布和出峰时间等方面的差异性.这些差异性可作为对烟尘来源及燃烧条件等因素判别的依据. 相似文献
66.
Worldwide energy demand has been growing steadily during the past five decades and most experts believe that this trend will continue to rise. The amount of emitted harmful emission gases increases in parallel with increasing energy consumption. This increase has forced many countries to take various precautions, and various restrictions on emitted emissions have been carried. In this study, effects of addition of oxygen containing nanoparticle additives to biodiesel on fuel properties and effects on diesel engine performance and exhaust emissions were investigated. Two different nanoparticle additives, namely MgO and SiO2, were added to biodiesel at the addition dosage of 25 and 50 ppm. Fuel properties, engine performance, and exhaust emission characteristics of obtained modified fuels were examined. As a result of this study, engine emission values NOx and CO were decreased and engine performance values slightly increased with the addition of nanoparticle additives. 相似文献
67.
PBDEs的来源特征、环境分布及污染控制 总被引:2,自引:0,他引:2
多溴联苯醚(Polybrominated diphenyl ethers,PBDEs)生产应用、环境分布与生态风险之间的关系将如何影响我国的未来,具体涉及到工业、环境、健康、人类繁衍等的社会问题.由于PBDEs阻燃效率高,热稳定性好,价格便宜,作为添加剂被广泛应用在电子、电器、化工、交通、建材、纺织、石油等领域的阻燃产品中.PBDEs进入环境后迁移扩散并富集于沉积物和生物体内,进入人体后引起肝脏毒性、内分泌干扰、神经毒性和生育能力下降等而危害人类的健康.基于此,从生产应用、品种生产量、分子的物理化学特性以及毒性等的文献数据分析了PBDEs的来源特征与环境危害,分析这些性质对环境分布与污染控制的基础支持关系;从沉积物、水体、大气、水生生物、人体5个方面考察了PBDEs的环境本底浓度变化、分配关系、迁移规律、时间效应,分析了生产、应用与扩散的多因素影响关系,发现全球性PBDEs污染物蔓延的现象,沉积物是主要的归趋场所,室内空气中的浓度远高于室外,水中浓度较低,水生生物和人体均能富集PBDEs,通过饮食、母乳和呼吸摄入,可实现代际传播,污染的分布呈现介质与区域的不同特征;污染控制需要考虑点源技术与面源修复的联合,结合PBDEs的物理性质、分子结构及其化学特性,统计分析了微生物法、光化学降解法和零价铁还原法的原理及其有效性,根据PBDEs在产品中存在与分布的特点,提出收集-分离-富集-超临界催化还原和氧化毁毒的工艺,针对实际环境(以电子垃圾塑料和流域水体及沉积物为对象)中的PBDEs进行回收或处理,结合材料如催化剂的应用,从动力学和热力学方面提高PBDEs无害化的效率.最后,从生产管理、环境监测、风险评价、技术集成等方面提出了未来的努力方向. 相似文献
68.
ZnBiYO4 was synthesized by a solid-state reaction method for the first time. The structural and photocatalytic properties of ZnBiYO4 were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and UV-Vis diffuse reflectance. ZnBiYO4 crystallized with a tetragonal spinel structure with space group I41/A. The lattice parameters for ZnBiYO4 were a = b = 11.176479 Å and c= 10.014323 Å. The band gap of ZnBiYO4 was estimated to be 1.58 eV. The photocatalytic activity of ZnBiYO4 was assessed by photodegradation of methyl orange under visible light irradiation. The results showed that ZnBiYO4 had higher catalytic activity compared with N-doped TiO2 under the same experimental conditions using visible light irradiation. The photocatalytic degradation of methyl orange with ZnBiYO4 or N-doped TiO2 as catalyst followed first-order reaction kinetics, and the first-order rate constant was 0.01575 and 0.00416 min-1 for ZnBiYO4 and N-doped TiO2, respectively. After visible light irradiation for 220 min with ZnBiYO4 as catalyst, complete removal and mineralization of methyl orange were observed. The reduction of total organic carbon, formation of inorganic products, SO42- and NO3-, and evolution of CO2 revealed the continuous mineralization of methyl orange during the photocatalytic process. The intermediate products were identified using liquid chromatography- mass spectrometry. The ZnBiYO4/(visible light) photocatalysis system was found to be suitable for textile industry wastewater treatment and could be used to solve other environmental chemical pollution problems. 相似文献
69.
70.
Gas explosion is one of the main disasters in coal mining. Plenty of coal gangue are generally distributed in the disaster areas in gob. Experiments were carried out to explore the propagation law of the gas explosion distributed by coal gangue. The variation characteristics of the overpressure, pressure rise rate, and flame shape with void fractions were analyzed. The results showed that the effect of the coal gangue on the explosion intensity changed from suppression to acceleration with the increase of void fraction, the flame front upstream blockage area changed from laminar state to turbulent divergent state, and a reverse flame was formed. When the void fraction of the coal gangue was 0.50–0.65, the maximum overpressure downstream of the blocked area were positively correlated with the void fraction and the critical suppression range was between 0.50 and 0.55. When the void fraction was lower than 0.50, the flame was quenched in the coal gangue, neither the flame nor the pressure could pass through the blocked area. It is helpful to guide the improvement of coal recovery process to avoid the expansion of the explosion impact in coalmine gob. 相似文献