摘要：
Graphene oxide (GO) is increasingly used in various applications, and the implications of this nano-sized material entering the natural environment are of great interest. GO is highly soluble in water, and its accumulation in soil could significantly alter the physical and mechanical properties of the soil. In this laboratory study, we mixed GO with a soil (clayey sand, SC) to systematically study the engineering properties and microstructure of the modified soil. The experimental results reveal that the physical and mechanical properties and microstructure of clayey sand can be significantly changed by the addition of a minute quantity of GO. The liquid limit and plasticity index of the soil steadily increased (up to a GO concentration of 0.08 wt%), whereas the plastic limit did not change significantly. The addition of GO (up to 0.08 wt%) into the soil generally decreased the soil's void ratio under a given hydrostatic consolidation pressure, while increasing its undrained shear strength. Such remarkable modifications of soil by minute amounts of GO can be attributed to the extremely high specific surface area of GO and its stable dispersion in water.
关键词：
Alternating pulse electric field;Calcium chloride;Electroosmosis;Reinforcement;Scanning electron microscopy;Weak soil
摘要：
Electroosmosis has been extensively employed as an effective method for the dewatering treatment of soils and thus the reinforcement of weak soils. At the microscopic level, this treatment process is inherently complex due to in situ chemical and electrochemical reactions, migration of ions and particles, and the dependence of zeta potential of various particles on the local pH value in the soil. This complexity has hindered further understanding of mechanisms underlying the electroosmosis technology. Here, we design an external electric field in which alternating pulse wave potentials were partially used to adjust the pH value of the soil and manipulate the dynamics of in situ formed nanoparticles and their interconnectivity. The experimental results reveal that the in situ formation of Ca-rich particles, instead of water drainage, may serve as the main mechanism underlying the observed soil reinforcement when using calcium chloride as the treatment electrolyte. The interconnectivity of such particles may be the key for the shear strength improvement without significant settlement of the soil.
摘要：
A total of 12 multielectrode array sensors were utilized to assess the individual effectiveness of two corrosion inhibitors and one coating under cyclic deicer exposure conditions. There were four sensor groups, and each group consisted of nine-pin probes that were fabricated from 1008 carbon steel, 304 stainless steel, and 1100 aluminum, respectively. A total of two environmental exposure tests were conducted, in which 2.3% NaCl and 3.0% MgCl2 solutions were used as salt, respectively. The two tests each included eight environmental cycles and with 24h per cycle. For all the exposed sensors, the most severe corrosion occurred at the beginning of the humidity stage. For sensors in the control group, MgCl2 exhibited a corrosion attack throughout the exposure period, whereas NaCl only exhibited an apparent corrosion attack during the humidity stage. Both the sensor corrosion rates and mass loss results indicate that the inhibitors had a much greater effect for MgCl2 than for NaCl. Although the coating showed significant benefits in protecting the metallic substrates, the cyclic exposure to MgCl2 led to greater coating deterioration than did NaCl. For validation, impedance measurements were conducted on carbon steel panels subjected to similar exposures, and three-dimensional laser profilometer scans were performed to characterize their surface morphology after the exposures.
摘要：
This laboratory study explores the development of plastering mortar modified by feather fibers, so as to lay the groundwork for utilizing poultry feathers in thermal- insulation materials and removing them from waste streams. The laboratory testing measured the consistency value, porosity, compressive strength and thermal conductivity of various cement mortar mixes as a function of feather fiber dosage. The experimental data were used to determine the appropriate weight fraction of feather fibers in the mortars for thermal insulation. The results indicate that the incorporation of feather fibers decreased the consistency value of fresh mortar and increased the surface roughness and porosity of hardened mortar. Under the investigated conditions, as the content of admixed fiber increased, both the compressive strength and thermal conductivity of hardened mortar decreased remarkably before leveling off. The desirable dosage of feather fibers falls in the range of 0.2-0.7% by mass of dry mixture.
关键词：
anti-icing;winter road maintenance;snow and ice control;fixed automated spray technology;evaluation;antigivrage;entretien des routes en hiver;contrôle de la neige et de la glace;technologie d’arrosage automatisé fixe;évaluation
摘要：
This paper synthesizes information obtained from a comprehensive literature review and agency surveys on the state of the practice of fixed automated spray technology (FAST) systems. Experience with FAST systems in North America and Europe has revealed a mixed picture. On the one hand, several studies have indicated reductions in mobile operation costs and significant reductions in crash frequency, resulting in favorable benefit-cost ratios. On the other hand, there have been a variety of problems related to activation frequency, system maintenance and training. Installing a FAST system is complex and the challenges are often site specific. However, the evaluations cited show that FAST systems can be cost-beneficial if their locations are carefully chosen and if the system is supported with reliable environmental sensors. Finally, it was found that application of FAST systems in North America have recently increased.
摘要：
Nano-silica particles were deposited on acid-etched hydrophilic aluminum (Al) substrates by immersion in well-dispersed nano-silica aqueous suspension and tetramethylamonium hydroxide, followed by a heat treatment. The surface was then further treated by a reaction with fluorosilane. The hydrophobicity, surface morphology, and mechanical properties of the coated Al substrates were investigated, along with their electrochemical properties over time of exposure to two NaCl solutions (0.3% and 3% by weight). All the coated Al surfaces exhibited a water contact angle of 155–158°, i.e., superhydrophobicity. The use of nano-silica suspension significantly enhanced the hydrophobicity of the coated Al. Artificial neural networks were used to provide quantitative understanding in how the microstructure of the treated Al surface contributed to its superhydrophobicity and electrochemical properties. When Ra, total (nano-roughness + micro-roughness) exceeds 450 nm, WCA is greater than 154°, independent of the nano/micro-roughness ratio (RRNM). FESEM and AFM images of these surfaces suggest that a rough two-length-scale hierarchical structure coupled with the low surface energy of fluorosilane topcoat led to the superhydrophobicity of the formed coatings. The coating prepared with the 0.2% nano-silica suspension (vs. other concentrations) featured the highest Young's modulus and the best corrosion protection to the Al substrate in both NaCl solutions.
摘要：
This paper analyzes key problems in multi-field coupling process between seepage mechanics and other physical processes (such as temperature field, stress field, solute transport, chemical action and so on) in environment engineering. The details of coupling process, such as the leachate migration law, the relationship between pollution and the soil phase is discussed. The treatment of engineering geology in liner systems is proposed, which takes waste and liner as one united artificial geological system. With theories of engineering geology and corresponding research methods, this artificial geological system’s engineering geology law and feature under the effect of leachate and landfill gas is studied. Finally it provides the possible research tendency of the coupling analysis in environment engineering.
会议名称：
2009 International Forum on Porous Flow and Applications(第十届全国渗流力学学术会议)
会议时间：
2009-04-26
会议地点：
武汉
会议论文集名称：
2009 International Forum on Porous Flow and Applications(第十届全国渗流力学学术会议)论文集
关键词：
Heat transfer models;analysis of groundwater advection;affecting of ground-loop heat ezchanger
摘要：
This paper reviews the heat transfer model and calculation methods on the ground-coupled heat pump (GCHP), and found that almost all the model did not consider the influence of groundwater seepage, although groundwater seepage on the pipe heat exchanger has a big influence. Based on the theory of groundwater seepage and heat transfer theory, a new mathematical model coupled with groundwater flow and heat transferring between heat exchanger and ground soil mass are established, which conceded of the heat conduction and the role of the common groundwater seepage of infiltration coupled heat transfer model, which can provides a theoretical support for the calculation and analysis of ground-coupled heat pump heat exchanger.
摘要：
Administrative guidance has been playing an important role in the economy and social life of our country. Because of the special statue, it is constantly causing fierce debating. The research of law o
