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Sample records for air entrained concrete

  1. Freeze-Thaw Durability of Air-Entrained Concrete

    OpenAIRE

    Huai-Shuai Shang; Ting-Hua Yi

    2013-01-01

    One of the most damaging actions affecting concrete is the abrupt temperature change (freeze-thaw cycles). The types of deterioration of concrete structures by cyclic freeze-thaw can be largely classified into surface scaling (characterized by the weight loss) and internal crack growth (characterized by the loss of dynamic modulus of elasticity). The present study explored the durability of concrete made with air-entraining agent subjected to 0, 100, 200, 300, and 400 cycles of freeze-thaw. T...

  2. A new technology for air-entrainment of concrete

    DEFF Research Database (Denmark)

    Laustsen, Sara; Hasholt, Marianne Tange; Jensen, Ole Mejlhede

    2008-01-01

    This paper describes a new technology for air-entrainment of concrete. The technology is based on the addition of dry superabsorbent polymers (SAP) to the concrete. A large amount of small internal water reservoirs are formed during mixing when SAP absorbs water and swells. The internal water......-entrainment include stability of the air void system and improved control of both the amount of added air and the air void size. The new technology based on SAP has been tested in freeze-thaw experiments, where the amount of surface scaling was measured. The results clearly show that SAP is beneficial for frost...... reservoirs are distributed throughout the concrete. During the hydration process the cement paste imbibes water from the water-filled SAP voids. Thereby the water-filled SAP voids turn into partly air-filled voids. The advantages of the SAP-based technology compared to traditional chemical air...

  3. Freeze-Thaw Durability of Air-Entrained Concrete

    Directory of Open Access Journals (Sweden)

    Huai-Shuai Shang

    2013-01-01

    Full Text Available One of the most damaging actions affecting concrete is the abrupt temperature change (freeze-thaw cycles. The types of deterioration of concrete structures by cyclic freeze-thaw can be largely classified into surface scaling (characterized by the weight loss and internal crack growth (characterized by the loss of dynamic modulus of elasticity. The present study explored the durability of concrete made with air-entraining agent subjected to 0, 100, 200, 300, and 400 cycles of freeze-thaw. The experimental study of C20, C25, C30, C40, and C50 air-entrained concrete specimens was completed according to “the test method of long-term and durability on ordinary concrete” GB/T 50082-2009. The dynamic modulus of elasticity and weight loss of specimens were measured after different cycles of freeze-thaw. The influence of freeze-thaw cycles on the relative dynamic modulus of elasticity and weight loss was analyzed. The findings showed that the dynamic modulus of elasticity and weight decreased as the freeze-thaw cycles were repeated. They revealed that the C30, C40, and C50 air-entrained concrete was still durable after 300 cycles of freeze-thaw according to the experimental results.

  4. Modification of the cast concrete mixture by air-entraining agents

    Directory of Open Access Journals (Sweden)

    N.I. Vatin

    2015-06-01

    Full Text Available The paper investigates the combined effect of superplasticizer based on the naphthalene lignosulfonate and the air-entraining surfactant agent on the fluidity, connectivity and air entrainment of concrete. The air-entraining surfactant agent contributes significantly into air entrainment and reduces the water gain and the mortar separation. It was found that under the introduction of air-entraining surfactant agents in the concrete mixture which contains the superplasticizer, the concrete mobility decreases even though the air-entraining agent is a plasticizer itself. The introduction of 0.1 % air-entraining agent decreases mobility: slump Abrams – 5–6 %, slump flow – 18–22 %. Besides, the effect of increasing the connectivity of the concrete mix is associated with the air entrainment. Regardless of the air-entraining surfactant agent, the superplasticizer reduces water separation, and does not have an air-entraining impact, and virtually has no effect on the air entrainment caused by the addition of the air-entraining agent. With the increasing quantity of the air-entraining surfactant agent in the concrete mix, regardless of the superplasticizer dosage, the amount of the entrained air increases from 3 to 7 %, and water separation is reduced to almost 0. Thus, the synergy of the superplasticizer and the air-entraining agent was negative, but it is possible to observe a positive effect in respect of the concrete mix connectivity.

  5. Effect of Fast Freeze-Thaw Cycles on Mechanical Properties of Ordinary-Air-Entrained Concrete

    OpenAIRE

    Huai-shuai Shang; Wei-qun Cao; Bin Wang

    2014-01-01

    Freezing-thawing resistance is a very significant characteristic for concrete in severe environment (such as cold region with the lowest temperature below 0°C). In this study, ordinary-air-entrained (O-A-E) concrete was produced in a laboratory environment; the compressive strength, cubic compressive strength of C50, C40, C30, C25, and C20 ordinary-air-entrained concrete, tensile strength, and cleavage strength of C30 ordinary-air-entrained concrete were measured after fast freeze-thaw cycles...

  6. Sulfate Attack Resistance of Air-entrained Silica Fume Concrete under Dry-Wet Cycle Condition

    Institute of Scientific and Technical Information of China (English)

    YANG Jiansen; WANG Peiming; LI Haoxin; YANG Xu

    2016-01-01

    Based on the erosion resistant coefficient, the effects of water-cement ratio, air-entrained, silica fume content and sand ratio on the sulfate attack resistance of air-entrained silica fume concrete were studied by orthogonal experiments in order to explore its sulfate attack resistance under dry-wet condition. A more signiifcant model of concrete resistance to sulfate attack was also established, thus this work provided a strategy reference for quantitative design of sulfate attack resistant concrete. The experimental results show that dry-wet cycle deteriorates the concrete resistance to the sulfate attack, and leads to the remarkable declines of concrete strength and sulfate resistance. Air bubbles in the air-entrained silica fume concrete lower and delay the damage resulted from the crystallization sulfate salt. However this delay gradually disappears when most of the close bubbles are breached by the alternative running of the sulfate salt crystallization and the permeating pressure, and then the air bubbles are iflled with sulfate salt crystallization. The concrete is provided with the strongest sulfate resistance when it is prepared with the 0.47 water-binder ratio, 6.0% air-entrained, 5% silica fume and 30% sand ratio. The erosion resistant coefifcientsK80 andK150 of this concrete are increased by 9%, 7%, 9%, and 5% respectively as compared with those of concretes without silica fume and air entraining.

  7. Study on Strength and Ultrasonic Velocity of Air-Entrained Concrete and Plain Concrete in Cold Environment

    Directory of Open Access Journals (Sweden)

    Huai-shuai Shang

    2014-01-01

    Full Text Available Nondestructive testing technology is essential in the quality inspection of repair, alteration, and renovation of the existing engineering, especially for concrete structure in severe environment. The objective of this work is to deal with the behavior of ultrasonic velocity and mechanical properties of plain concrete and air-entrained concrete subjected to freeze-thaw cycles (F-T-C. The ultrasonic velocity and mechanical properties (tensile strength, compressive strength, cubic compressive strength, and splitting strength of C30 air-entrained concrete and plain concrete with different water-cement ratio (water-cement ratio was 0.55, 0.45, and 0.50, resp. after F-T cycles were measured. The influences of F-T cycles on ultrasonic velocity and mechanical properties of C30 air-entrained concrete and plain concrete were analyzed. And the relationship between mechanical properties and ultrasonic velocity was established. The experimental results can be useful for the design of new concrete structure, maintenance and life prediction of existing concrete structure such as offshore platform and concrete dock wall.

  8. BEHAVIOR OF AIR-ENTRAINED CONCRETE AFTER FREEZE-THAW CYCLES

    Institute of Scientific and Technical Information of China (English)

    Huaishuai Shang; Yupu Song; Jinping Ou

    2009-01-01

    The experimental study of air-entrained concrete specimens subjected to different cycles of freeze-thaw was completed. The dynamic modulus of elasticity, weight loss, the cubic compressive strength, compressive strength, tensile strength and cleavage strength of air-entrained concrete were measured after 0, 100, 200, 300, 400 cycles of freeze-thaw. The experimental results showed that the dynamic modulus of elasticity and strength decreased as the freeze-thaw was repeated. The influences of freeze-thaw cycles on the mechanical properties, the dynamic modulus of elasticity and weight loss were analyzed according to the experimental results. It can serve as a reference for the maintenance, design and the life prediction of dams, hydraulic structures, offshore structures, concrete roads and bridges in northern cold regions.

  9. Water Entrainment in Concrete

    DEFF Research Database (Denmark)

    Jensen, Ole Mejlhede; Hansen, Per Freiesleben

    This report gives a survey of different techniques for incorporation of designed, water-filled cavities in concrete: Water entrainment. Also an estimate of the optimum size of the water inclusions is given. Water entrainment can be used to avoid self-desiccation and self-desiccation shrinkage...... during hydration [1,26]. What is needed is some sort of container which retains the shape of the water when mixed into the concrete. The container may function based on several different physical or chemical principles. Cells and gels are examples of containers found in nature. A cell membrane provides...... a boundary to water, whereas a polymer network incorporates water in its intersticious space with its affinity due to interaction energy and polymer entropy. Such containers allow water to be stored as an entity. In relation to concrete the water encapsulation may be accomplished either before or after start...

  10. Improving the behavior of concrete exposed to fire by using an air entraining agent (AEA: Assessment of spalling

    Directory of Open Access Journals (Sweden)

    D'Aloia L.

    2013-09-01

    Full Text Available Several concrete mixes have been designed to evaluate the influence of an air entraining agent (AEA on spalling. Tests have been performed under the ISO curve (occasionally under the HCinc curve on specimens of various sizes and shapes to assess spalling. Results were somehow erratic on the smallest specimens whereas the beneficial effect of the air-bubble network could be emphasized on slabs.

  11. A review of the interference of carbon containing fly ash with air entrainment in concrete

    DEFF Research Database (Denmark)

    Pedersen, Kim Hougaard; Jensen, Anker Degn; Skjøth-Rasmussen, Martin Skov;

    2008-01-01

    adsorption capacity per mass of carbon. Cases reporting increased residual carbon content due to low-NO, combustion are described, together with observations from a pilot scale experiment, where increased AEA adsorption capacity of carbon appeared to relate with firing at low-NO, conditions. Post-treatment...... on the adsorption capacity of AEAs. The type of fuel used in the combustion process influences the amount and properties of the residual carbon. Fly ash derived from bituminous coal has generally higher carbon content compared with fly ash produced from subbituminous coal or lignite, but shows a lower AEA...... methods applied to improve fly ash quality are described in the review. Ozonation, thermal treatment and physical cleaning of carbon have been found to improve the fly ash performance for concrete utilization. Ultimately, recommendations for further work are outlined in the discussion....

  12. The effect of low-NOx combustion on residual carbon in fly ash and its adsorption capacity for air entrainment admixtures in concrete

    DEFF Research Database (Denmark)

    Pedersen, Kim Hougaard; Jensen, Anker Degn; Dam-Johansen, Kim

    2010-01-01

    Fly ash from pulverized coal combustion contains residual carbon that can adsorb the air-entraining admixtures (AEAs) added to control the air entrainment in concrete. This is a problem that has increased by the implementation of low-NOx combustion technologies. In this work, pulverized fuel has...... by up to a factor of 25. This was due to a lower carbon content in the ash and a lower specific AEA adsorptivity of the carbon. The latter was suggested to be caused by changes in the adsorption properties of the unburned char and a decreased formation of soot, which was found to have a large AEA...... adsorption capacity based on measurements on a carbon black. The NOx formation increased by up to three times with more oxidizing conditions and thus, there was a trade-off between the AEA requirements of the ash and NOx formation. The type of fuel had high impact on the AEA adsorption behavior of the ash...

  13. Air entrainment in hairy surfaces

    Science.gov (United States)

    Nasto, Alice; Regli, Marianne; Brun, P.-T.; Alvarado, José; Clanet, Christophe; Hosoi, A. E.

    2016-07-01

    Motivated by diving semiaquatic mammals, we investigate the mechanism of dynamic air entrainment in hairy surfaces submerged in liquid. Hairy surfaces are cast out of polydimethylsiloxane elastomer and plunged into a fluid bath at different velocities. Experimentally, we find that the amount of air entrained is greater than what is expected for smooth surfaces. Theoretically, we show that the hairy surface can be considered as a porous medium and we describe the air entrainment via a competition between the hydrostatic forcing and the viscous resistance in the pores. A phase diagram that includes data from our experiments and biological data from diving semiaquatic mammals is included to place the model system in a biological context and predict the regime for which the animal is protected by a plastron of air.

  14. Local air entrainment and detrainment

    OpenAIRE

    Kobus, Helmut

    1984-01-01

    Air and water are usually well separated by gravity due to their extreme difference in specific weight. Whenever they are mixed, however, they give rise to a very complex two-phase flow situation. The hydraulic engineer is often faced with the problem of estimating the effects of entrained air upon the flow, because this may be essential for the safe operation of a hydraulic structure.The predominant mechanism in generating airwater mixtures is the inclusion of air at the surface of flowing w...

  15. 关于加气混凝土砌块墙体质量控制的探讨%Discuss the Quality Control of Air Entraining Concrete Block Wall

    Institute of Scientific and Technical Information of China (English)

    贺玉超

    2014-01-01

    Air entraining concrete block is the common con-crete block in building wal , and the crack problems in air entraining concrete block wal are common in the building wal , which brought great trouble to the construction enterp-rises. The article analyzes the factors to result in the crack of the wal , and effective prevention and improvement measures are put forward.%加气混凝土砌块是建筑墙体中较为常见的砌块,加气混凝土砌块墙体裂缝问题在建筑房屋墙体中比较常见,给建筑施工企业带来了极大的麻烦。文章对导致墙体开裂的因素进行了深入分析,并提出了有效地防治及改善措施。

  16. Effect of air entraining admixture on mechanical properties and durability of coarse porous concrete%引气剂对大孔混凝土力学性能及耐久性的影响

    Institute of Scientific and Technical Information of China (English)

    张蔚

    2012-01-01

    The addition of air entraining admixture could improve durability of ordinary concrete effectively, while the effect on coarse porous concrete is not obvious. The article describe the reseach on the effect of air entraining admixture on mechanical properties and durability of coarse porous con- crete. The result shows that the compressive strength and resistance properties to freeze--thaw could be improved with the appropriate amount of air entraining admixture by testing.%引气剂能有效改善普通混凝土的耐久性.但对大孔混凝土性能的影响不明确。本文通过试验,研究不同掺量引气剂对大孔混凝土力学性能及耐久性能的影响。结果表明,适量的引气剂能够增强大孔混凝土的抗压强度和改善抗冻性能。

  17. 防冻剂对混凝土引气剂气泡稳定性能影响研究∗%Impact study of anti-freezing agent on bubble stability performance of concrete air-entraining agent

    Institute of Scientific and Technical Information of China (English)

    张向东; 李庆文; 李广华; 李桂秀

    2015-01-01

    为探究防冻剂对混凝土引气剂气泡稳定性能的影响,考虑4种防冻剂及不同掺量等敏感性因素进行水泥稀浆摇泡实验,分析其对引气剂起泡与稳泡能力影响及作用机理。结果表明,建立摇泡实验的气泡体积衰减指数模型,其参数能表征不同引气剂起泡与稳泡能力;硝酸钙对皂苷类引气剂稳泡能力有正作用,防冻剂对其起泡能力均有负作用;乙二醇对苯磺酸盐类引气剂起泡能力有正作用,对其稳泡能力有正作用,表现为亚硝酸钙>硝酸钙>乙二醇;4种防冻剂对掺皂苷类引气剂的新拌混凝土含气量均有负影响,其显著性为乙二醇最强,亚硝酸钙最弱,钙盐类防冻剂对掺苯磺酸盐类引气剂均有负作用,乙二醇对其有正作用。%In order to explore the influence of anti-freezing agent on bubble stability performance of concrete air-entraining agent,the cement slurry bubble test was carried out considering sensitivity factors which was four kinds of anti-freezing agents and different dosages,and analyzed its effects on foaming ability,stabilizing foam ability and mechanism.The results revealed that bubble volume attenuation index model of shake bubble test was set up,which parameters characterized the foaming ability and stabilizing foam ability of different air-en-training agents.Calcium nitrate had a positive effect on stabilizing foam ability of the saponins air-entraining agent,and anti-freezing agents had a negative effect on it.Ethylene glycol had a positive effect on foaming abili-ty of the benzene sulfonate air-entraining agent,the significance of improving the stabilizing foam ability was calcium nitrite>calcium nitrate>ethylene glycol.Four kinds of anti-freezing agents all had a negative impact on the air content of fresh concrete mixed with the saponins air-entraining agent,the most significant of it was ethylene glycol,and the least significant was calcium nitrite

  18. Effect of low atmospheric pressure of plateau environment on air content and bubble stability of air-entrained concrete%高原低气压环境对引气混凝土含气量及气泡稳定性的影响

    Institute of Scientific and Technical Information of China (English)

    李雪峰; 付智

    2015-01-01

    该文利用低气压试验箱模拟高原气压环境,试验研究了不同配合比及初始含气量水平下环境气压的降低对引气混凝土含气量及其气泡稳定性的影响。结果表明:与常压相比,环境气压的降低能够显著削弱引气剂的引气能力,当混凝土配合比及引气剂掺量一定时,混凝土含气量随环境气压降低呈线性减少,当环境气压降低至50 kPa时,混凝土含气量降低约20%~49%。另外,低气压条件下混凝土气泡稳定性变差,具体表现为混凝土含气量经时损失变大,延长振捣时间导致低压混凝土损失更多气泡,二者均使低压下硬化混凝土的气泡间距系数增大,影响混凝土抗冻性。因此,在高原地区应通过采取优选引气剂类型、增大引气剂掺量以及避免过振等技术措施,以确保高原地区引气混凝土含气量能够达到抗冻设计要求。%The effect of atmospheric pressure reduction of environment on air content and bubble stability of air-entrained concrete were experimentally studied using low-pressure test chamber to stimulate the plateau environment. Three different mixing proportions and three different levels of the initial air content of concretes were prepared for study, and four different common types of air-entraining admixture, saponin, alkyl sulfonate, abietic soap and polyether, were used in the experiments. The results indicated that the change of atmospheric pressure of environment had a significant impact on the performance of air-entraining admixtures. When the mix proportions of concrete and the amount of air-entraining admixtures took a certain value respectively, the air content of fresh concrete decreased linearly with the drop of atmospheric pressure. When the atmospheric pressure was 50 kPa, the air content of fresh concrete fell by roughly 20% to 49%. The higher the air content of fresh concrete mixed in normal atmospheric pressure, the faster the air

  19. EFFECTS OF ENTRAINED AIR MANNER ON CAVITATION DAMAGE*

    Institute of Scientific and Technical Information of China (English)

    WU Jian-hua; LUO Chao

    2011-01-01

    Early in 1953 the experiments by Peterka proved that air entrainment has effects on decreasing cavitation damage. This technology has been widely used in the release works of high dams since the inception of air entrainment in the Grand Goulee Dam in 1960. Behavior, mechanism and application of air entrainment for cavitation damage control have been investigated for over half century. However, severe cavitation damage happened due to complex mechanism of air entrainment. The effects of air entrainment are related to many factors, including geometric parameters, hydraulic parameters and entrained air manners. In the present work an experimental set-up for air entrainment was specially designed, the behavior of reducing cavitation damage was experimentally investigated in the three aspects of entrained air pressure, air tube aera and air tube number. The results show that magnitude of reduction of cavitation damage is closely related to the entrained air tube number as well as entrained air pressure, air tube aera, and that the effect through three air tubes is larger than that through single air tube although the entrained air tubes have the same sum of tube aera, that is, 1 + 1 + 1 > 3. Therefore, it is important to design an effective manner of air entrainment.

  20. Effect of the Entrained Air Void on Strength and Interfacial Transition Zone of Air-Entrained Mortar

    Institute of Scientific and Technical Information of China (English)

    GAO Hui; ZHANG Xiong; ZHANG Yongjuan

    2015-01-01

    In order to facilitate the development and application of air entraining agents (AEA) in the high performance concrete, entrained air void structure parameters (air void size range from 10 to 1 600 μm) of 28 d sifted mortar were measured by image analysis method. The relationship between the air void size distribution and strength of mortar was studied by methods of grey connection analysis and multiple linear regression analysis. The multiple linear regression equation was established with a correlation coefifcient of 0.966. The weight of the affection of hierarchical porosity on the compressive strength ratio was also obtained. In addition, the effect of air voids on the paste-aggregate interfacial transition zone (ITZ) was analyzed by microhardness. The results show that the correlation between different pore size range and the compressive strength is negative. The effect of air void size distribution on 28 days compressive strength is different: under the condition of similar total porosity, with the increase of the porosity of the air void size, ranging from 10 to 200 μm, and the decrease of the porosity, ranging from 200 to 1 600 μm, the average air void diameter and mean free spacing are decreased; as well as the width of ITZ. On the contrary, the microhardness of the ITZ is increased while the compressive strength loss is decreased.

  1. Entrainment Rate in Shallow Cumuli: Dependence on Entrained Dry Air Sources and Probability Density Functions

    Science.gov (United States)

    Lu, C.; Liu, Y.; Niu, S.; Vogelmann, A. M.

    2012-12-01

    In situ aircraft cumulus observations from the RACORO field campaign are used to estimate entrainment rate for individual clouds using a recently developed mixing fraction approach. The entrainment rate is computed based on the observed state of the cloud core and the state of the air that is laterally mixed into the cloud at its edge. The computed entrainment rate decreases when the air is entrained from increasing distance from the cloud core edge; this is because the air farther away from cloud edge is drier than the neighboring air that is within the humid shells around cumulus clouds. Probability density functions of entrainment rate are well fitted by lognormal distributions at different heights above cloud base for different dry air sources (i.e., different source distances from the cloud core edge). Such lognormal distribution functions are appropriate for inclusion into future entrainment rate parameterization in large scale models. To the authors' knowledge, this is the first time that probability density functions of entrainment rate have been obtained in shallow cumulus clouds based on in situ observations. The reason for the wide spread of entrainment rate is that the observed clouds are affected by entrainment mixing processes to different extents, which is verified by the relationships between the entrainment rate and cloud microphysics/dynamics. The entrainment rate is negatively correlated with liquid water content and cloud droplet number concentration due to the dilution and evaporation in entrainment mixing processes. The entrainment rate is positively correlated with relative dispersion (i.e., ratio of standard deviation to mean value) of liquid water content and droplet size distributions, consistent with the theoretical expectation that entrainment mixing processes are responsible for microphysics fluctuations and spectral broadening. The entrainment rate is negatively correlated with vertical velocity and dissipation rate because entrainment

  2. Impact of air entrainment on the microstructure and mechanical performance of high performance mortar

    OpenAIRE

    Dils, Jeroen; Boel, Veerle; De Schutter, Geert

    2015-01-01

    At the Magnel Laboratory for Concrete Research an intensive vacuum mixer which can regulate the air pressure is available. As such the amount of entrapped air in cementitious materials can be varied. The effect of the reduced air content due to vacuum mixing on the rheology and workability was already investigated in previous work. Furthermore, the previous work investigated the influence of entrained air on the rheological properties. The impact of vacuum mixing on the compressive strength a...

  3. Study on effects of air-entraining and anti-foaming on performance and apparent morphology of fair-faced concrete%引气剂与消泡剂对清水混凝土性能与表观形貌的影响

    Institute of Scientific and Technical Information of China (English)

    黄快忠; 龚明子; 陈茜; 刘尊玉; 李式龙; 连亚明

    2014-01-01

    There are important effects of air-entraining admixture and anti-foaming admixture on performance of concrete.It discussed the influence of the different air-entraining and anti-foaming ratio in polycarboxylate superplasticizer on concrete fluidity,air content and strength.The optimal ratio between the two made plain fair-faced concrete showed better performance and apparent morphology.The re-sults showed that,when air-entraining admixture dosage was two over ten thousand and anti-foaming dosage was one over ten thousand, the apparent morphology of fair-faced concrete was the best.%引气剂与消泡剂对清水混凝土的性能与表观形貌有重要的影响。论述了不同引气和消泡比例的聚羧酸高效减水剂对清水混凝土流动性、含气量、强度与硬化后表观形貌的影响。为使清水混凝土表现出更好的性能和美观的表面形貌,两者存在一个最佳比例。结果表明:当引气剂掺量为2%、消泡剂掺量为1%时,清水混凝土的表观形貌最佳。

  4. Air entrainment by plunging water jets

    NARCIS (Netherlands)

    Van de Sande, E.

    1974-01-01

    Gas entrainment caused by the impact of liquid jets upon liquid pool surfaces is a subject which has received too little attention. This well-known phenomenon,which occurs In nature and in numerous industrial operations, has only recently received interest from scientific workers. The influence on p

  5. Entrainment of Air into Vertical Jets in a Crosswind

    Science.gov (United States)

    Roberts, K. K.; Solovitz, S.; Freedland, G.; Camp, E.; Cal, R. B.; Mastin, L. G.

    2015-12-01

    During volcanic eruptions, ash concentration must be determined for aviation safety, but the limiting threshold is difficult to distinguish visually. Computational models are typically used to predict ash concentrations, using inputs such as plume height, eruptive duration, and wind speeds. The models also depend on empirical parameters, such as the entrainment of atmospheric air as a ratio of the air inflow speed and the jet speed. Entrainment of atmospheric air plays a critical role in the behavior of volcanic plumes in the atmosphere, impacting the mass flow rate, buoyancy, and particle concentration of the plume. This process is more complex in a crosswind, leading to greater uncertainty in the model results. To address these issues, a laboratory-scale study has been conducted to improve the entrainment models. Observations of a vertical, unconfined jet are performed using Particle Image Velocimetry, while varying jet density using different compressed gases and Reynolds number. To test the effects of a crosswind on plume entrainment rates, these are then compared with similar jet experiments in a wind tunnel. A series of jet geometries, jet speeds and tunnel speeds are considered. The measured velocities are used to determine the entrainment response, which can be used to determine ash concentration over time as atmospheric air is entrained into the plume. We also quantify the mean and the fluctuations in flow velocity.

  6. RESEARCH ON EARLY STRENGTH AND FREEZE-PROOF RESISTANCE OF AIR-ENTRAINED CONCRETE UNDER 3 ℃CURING%3℃养护下引气混凝土早期强度及抗冻性能研究

    Institute of Scientific and Technical Information of China (English)

    张凯; 王起才; 王庆石; 李盛; 李建新

    2015-01-01

    采用强度试验、压汞法、气孔分析法、快速冻融法,以低温(3±0.2)℃养护下引气混凝土为研究对象,对混凝土的强度、孔隙结构及抗冻耐久性进行了研究。结果表明:在3℃养护下,随着含气量的提高,孔径均匀分布,显著改善了混凝土的内部孔隙结构,但比标准养护条件下同等含气量混凝土的孔结构粗化。为更好地阐述混凝土实际强度受含气量的影响,由孔隙结构可进一步推算出3℃养护下混凝土的实际抗压强度,并与标准养护条件下实际抗压强度对比,显示两者之间的不同。%The strength, the pore structure and freeze-proof durability of air-entrained concrete under 3 ℃temperature curing and with different air contents were researched by taking air-entrained concrete under low temperature curing (3 ±0.2 ) ℃ as the object, adopting strength test mercury intrusion method, pore analytical method and fast freeze-thaw method.The results showed that when concrete of 3 ℃ temperature curing, as the air content was increased, the distribution of pore diameter was uniform and the interior pore structure of concrete was improved significantly, however, the pore structure under the room curing at the same air content of concrete was lower than under 3 ℃curing.In order to expound the influence of air content on the actual concrete strength in an even better fashion, the concrete compressive strength under 3 ℃curing can further be estimated by pore structure, which was compared with the room curing actual compressive strength, showing the difference between the two.

  7. Using Neutron Radiography to Quantify Water Transport and the Degree of Saturation in Entrained Air Cement Based Mortar

    Science.gov (United States)

    Lucero, Catherine L.; Bentz, Dale P.; Hussey, Daniel S.; Jacobson, David L.; Weiss, W. Jason

    Air entrainment is commonly added to concrete to help in reducing the potential for freeze thaw damage. It is hypothesized that the entrained air voids remain unsaturated or partially saturated long after the smaller pores fill with water. Small gel and capillary pores in the cement matrix fill quickly on exposure to water, but larger pores (entrapped and entrained air voids) require longer times or other methods to achieve saturation. As such, it is important to quantitatively determine the water content and degree of saturation in air entrained cementitious materials. In order to further investigate properties of cement-based mortar, a model based on Beer's Law has been developed to interpret neutron radiographs. This model is a powerful tool for analyzing images acquired from neutron radiography. A mortar with a known volume of aggregate, water to cement ratio and degree of hydration can be imaged and the degree of saturation can be estimated.

  8. Dispersal and air entrainment in unconfined dilute pyroclastic density currents

    Science.gov (United States)

    Andrews, Benjamin J.

    2014-09-01

    Unconfined scaled laboratory experiments show that 3D structures control the behavior of dilute pyroclastic density currents (PDCs) during and after liftoff. Experiments comprise heated and ambient temperature 20 μm talc powder turbulently suspended in air to form density currents within an unobstructed 8.5 × 6 × 2.6-m chamber. Comparisons of Richardson, thermal Richardson, Froude, Stokes, and settling numbers and buoyant thermal to kinetic energy densities show good agreement between experimental currents and dilute PDCs. The experimental Reynolds numbers are lower than those of PDCs, but the experiments are fully turbulent; thus, the large-scale dynamics are similar between the two systems. High-frequency, simultaneous observation in three orthogonal planes shows that the currents behave very differently than previous 2D (i.e., confined) currents. Specifically, whereas ambient temperature currents show radial dispersal patterns, buoyancy reversal, and liftoff of heated currents focuses dispersal along narrow axes beneath the rising plumes. The aspect ratios, defined as the current length divided by a characteristic width, are typically 2.5-3.5 in heated currents and 1.5-2.5 in ambient temperature currents, reflecting differences in dispersal between the two types of currents. Mechanisms of air entrainment differ greatly between the two currents: entrainment occurs primarily behind the heads and through the upper margins of ambient temperature currents, but heated currents entrain air through their lateral margins. That lateral entrainment is much more efficient than the vertical entrainment, >0.5 compared to ˜0.1, where entrainment is defined as the ratio of cross-stream to streamwise velocity. These experiments suggest that generation of coignimbrite plumes should focus PDCs along narrow transport axes, resulting in elongate rather than radial deposits.

  9. Effects of Air Entrainment on Fluid Transients in Pumping Systems

    Directory of Open Access Journals (Sweden)

    T.S Lee

    2008-01-01

    Full Text Available In pumping installations, fluid transient computations are necessary to achieve safety, efficiency and economy in design and operation. In some systems, where air content and air entrainment exist, such computations become highly inaccurate when constant wave speed is assumed. In this paper, a numerical model and a computational procedure have been developed to investigate the effects of air entrainment on the pressure transient in pumping systems. Free gas in the fluid and cavitation at the fluid vapour pressure were modeled in the form of variable wave speed model, which was numerically solved by the method of characteristics. This model was tested for the case of pump trips due to power failures. The pressure transient results obtained by this variable wave speed model were analyzed and compared with those results obtained by constant wave speed model and with the experimental results of other investigators.

  10. Universal mechanism for air entrainment during liquid impact

    CERN Document Server

    Hendrix, Maurice H W; van der Meer, Devaraj; Lohse, Detlef; Snoeijer, Jacco H

    2015-01-01

    When a mm-sized liquid drop approaches a deep liquid pool, both the interface of the drop and the pool deform before the drop touches the pool. The build up of air pressure prior to coalescence is responsible for this deformation. Due to this deformation, air can be entrained at the bottom of the drop during the impact. We quantify the amount of entrained air numerically, using the Boundary Integral Method (BIM) for potential flow for the drop and the pool, coupled to viscous lubrication theory for the air film that has to be squeezed out during impact. We compare our results to various experimental data and find excellent agreement for the amount of air that is entrapped during impact onto a pool. Next, the impact of a rigid sphere onto a pool is numerically investigated and the air that is entrapped in this case also matches with available experimental data. In both cases of drop and sphere impact onto a pool the numerical air bubble volume V_b is found to be in agreement with the theoretical scaling V_b/V_...

  11. Modeling of Kinetics of Air Entrainment in Water Produced by Vertically Falling Water Flow

    Directory of Open Access Journals (Sweden)

    Adelė VAIDELIENĖ

    2014-09-01

    Full Text Available This study analyzes the process of air entrainment in water caused by vertically falling water flow in the free water surface. The new kinetic model of air entrainment in water was developed. This model includes the process of air entrapment, as well as air removal, water sputtering and resorption. For the experimental part of this study a new method based on digital image processing was developed. Theoretical and experimental methods were used for determining air concentration and its distribution in water below the air-water interface. A new presented mathematical model of air entrainment process allows determining of air bubbles and water droplets concentrations distribution. The obtained theoretical and experimental results were in good agreement. DOI: http://dx.doi.org/10.5755/j01.ms.20.3.4871

  12. Development of a New Type of Green Switch Air Entraining Agent for Wet-Mix Shotcrete and Its Engineering Application

    Directory of Open Access Journals (Sweden)

    Guoming Liu

    2016-01-01

    Full Text Available Air entraining agent (AEA can bring a lot of microbubbles into fresh concrete for improving its fluidity; however, high fluidity has adverse effect on the shootability of wet-mix shotcrete. In order to solve the contradictory issue, the paper developed a new type of green switch air entraining agent (GSAE that can improve both the pumpability and shootability. The single-admixture and combination tests containing foaming ability and surface tension were performed with Deer agitator and automatic tension meter. The new AEA was developed with two constituents A and B. A was prepared with Sapindus mukorossi(S-1, dodecyl trimethyl ammonium chloride(1231, and polyacrylamide. B was prepared with lauryl sodium sulfate (K12 and silicone oil. The mass mix proportion was S-1 : 1231 : polyacrylamide : K12 : silicone oil = 1 : 0.33 : 0.2 : 0.33 : 0.47. The application method of GSAE proposed that A was premixed with fresh concrete and then B was added at nozzle. Experimental investigation showed that the optimal mixing amount of GSAE was 0.1%–0.2% relative to cement. All performance measured of wet-mix shotcrete with 0.12% GSAE met the first-grade product requirements of the China National Standard. Compared with the conventional type of AEA, the proposed GSAE is capable of effectively improving pumpability and shootability.

  13. Numerical investigation of air-entrainment in skimming flow over stepped spillways

    Directory of Open Access Journals (Sweden)

    Jiemin Zhan

    2016-05-01

    Full Text Available As a widely used flood energy dissipator, the stepped spillway can significantly dissipate the kinetic or hydraulic energy due to the air-entrainment in skimming flow over the steps. The free-surface aeration involves the sharp deformation of the free surface and the complex turbulent shear flows. In this study, the volume of fluid (VOF, mixture, and Eulerian methods are utilized to simulate the air-entrainment by coupling with the Reynolds-averaged Navier–Stokes/large eddy simulation (RANS/LES turbulence models. The free surface deformation, air volume fraction, pressure, and velocity are compared for the three different numerical methods. Only the Eulerian+RANS method fails to capture the free-surface aeration. The air volume fraction predicted by the VOF+LES method best matches the experimental measurement, while the mixture+LES method predicts the inception point of the air entrainment more accurately.

  14. What's All the Talc About? Air Entrainment in Dilute Pyroclastic Density Currents

    Science.gov (United States)

    Marshall, B. J.; Andrews, B. J.; Fauria, K.

    2015-12-01

    A quantitative understanding of air entrainment is critical to predicting the behaviors of dilute Pyroclastic Density Currents (PDCs), including runout distance, liftoff, and mass fractionation into co-PDC plumes. We performed experiments in an 8.5x6x2.6 meter tank using 20 micron talc powder over a range of conditions to describe air entrainment as a function of temperature, duration and mass flux. The experiments are reproducible and are scaled with respect to the densimetric and thermal Richardson numbers (Ri and RiT), Froude number, thermal to kinetic energy density ratio (TEb/KE), Stokes number, and Settling number, such that they are dynamically similar to natural dilute PDCs. Experiments are illuminated with a swept laser sheet and imaged at 1000 Hz to create 3D reconstructions of the currents, with ~1-2 cm resolution, at up to 1.5 Hz. An array of 30 high-frequency thermocouples record the precise temperature in the currents at 3 Hz. Bulk entrainment rates are calculated based on measured current volumes, surface areas, temperatures and velocities. Entrainment rates vary from ~0-0.9 and do not show simple variation with TEb/KE, Ri, or RiT. Entrainment does, however, increase with decreasing eruption duration and increasing mass flux. Our results suggest that current heads entrain air more efficiently than current bodies (>0.5 compared to ~0.1). Because shorter duration currents have proportionally larger heads, their bulk entrainment rates are controlled by those heads, whereas longer duration currents are dominated by their bodies. Our experiments demonstrate that air entrainment, which exerts a fundamental control on PDC runout and liftoff, varies spatially and temporally within PDCs.

  15. Quantification of hood effectiveness and entrained subsurface air in a Seattle Hospital

    Energy Technology Data Exchange (ETDEWEB)

    Dietz, R.N.; Goodrich, R.W.

    1994-05-01

    An underground 3-story wing of a hospital having problems with sewer air odors was tested with perfluorocarbon tracer (PFI) technology to quantify the performance of the mechanical ventilation system and determine the extent of sewer air entrainment and chemical hood effectiveness.

  16. De-entrainment on vertical elements in air droplet cross flow

    International Nuclear Information System (INIS)

    De-entrainment phenomena on vertical elements in air-water droplet cross flow are generated using a horizontal array of water spray nozzles and a draft-induced wind tunnel. These conditions are used to obtain experimental values of the de-entrainment efficiency of isolated elements (25.4-, 63.5-, and 101.6-mm-diam cylinders and a 76.2-mm-square tube), and of an array of 101.6-mm-diam cylinders. A flow model is developed that extrapolates the de-entrainment efficiency of isolated elements through the use of a correlation for the interference effect to predict the efficiency of large arrays of similar elements. This simple model is shown to provide a good prediction of the de-entrainment efficiency of arrays in terms of the efficiency of an isolated element

  17. Experiments on air entrainment into SCS by vortex formation during mid-loop operation

    Energy Technology Data Exchange (ETDEWEB)

    Chug, Moon Ki; Song, Chul Hwa; Jung, Heung Joon; Won, Soon Yeon; Min, Kyung Ho; Chang, Keun Sun [Korea Atomic Energy Res. Inst., Taejon (Korea, Republic of)

    1994-05-01

    In this final report, the phenomena of air entrainment into SCS suction nozzle by vortex formation during Mid-Loop operation condition are experimentally investigated. The critical submergence is determined for various types of suction nozzle, and the measurements of velocity distribution are performed in the flow fields near the T-shaped suction nozzle. 11 refs., 41 figs., 13 tabs.

  18. The entrainment of air by water jet impinging on a free surface

    Energy Technology Data Exchange (ETDEWEB)

    Soh, Wee King [University of Wollongong, School of Mechanical, Materials and Mechatronics Engineering, Northfields Ave, NSW (Australia); Khoo, Boo Cheong [National University of Singapore, Department of Mechanical and Production Engineering, 10 Kent Ridge Crescent (Singapore); Yuen, W.Y. Daniel [BlueScope Steel Research, Port Kembla, NSW (Australia)

    2005-09-01

    High-speed cine and video photographs were used to capture the flow patterns of a column of water jet impinging into a pool of water. The impact results in air entrainment into water in the form of a void with no mixing between the water in the jet and the surrounding water. Conservation of fluid momentum shows that the rate of increase of the height of the air void depends on the drag coefficient of the jet front. By neglecting the frictional losses, the application of energy conservation yields an expression that relates the maximum height of the air void with the properties of the water jet. (orig.)

  19. Large Field of View PIV Measurements of Air Entrainment by SLS SMAT Water Sound Suppression System

    Science.gov (United States)

    Stegmeir, Matthew; Pothos, Stamatios; Bissell, Dan

    2015-11-01

    Water-based sound suppressions systems have been used to reduce the acoustic impact of space vehicle launches. Water flows at a high rate during launch in order to suppress Engine Generated Acoustics and other potentially damaging sources of noise. For the Space Shuttle, peak flow rates exceeded 900,000 gallons per minute. Such large water flow rates have the potential to induce substantial entrainment of the surrounding air, affecting the launch conditions and generating airflow around the launch vehicle. Validation testing is necessary to quantify this impact for future space launch systems. In this study, PIV measurements were performed to map the flow field above the SMAT sub-scale launch vehicle scaled launch stand. Air entrainment effects generated by a water-based sound suppression system were studied. Mean and fluctuating fluid velocities were mapped up to 1m above the test stand deck and compared to simulation results. Measurements performed with NASA MSFC.

  20. Effect of Air Entrainment on Breakup of Plunging Liquid Jet into Water Pool

    International Nuclear Information System (INIS)

    The steam explosion intensity is largely dependent upon the degree of volumetric fractions of melt droplets and steam in the fuel-coolant mixture. The rate of melt jet breakup and droplet sizes are, therefore, the key physical parameters in the analysis of FCIs. In a recent OECD/NEA international program SERENA, the areas where research may be needed to reduce the level of uncertainties in the code predictions have been identified. The predicted void fractions in the mixture were generally much higher than experimental data and a deficiency in melt jet breakup modeling would be one of the primary causes. In this paper, an extended study of non-boiling liquid jet breakup from the previous jet breakup experiment is reported with an emphasis on the role of air entrainment by plunging liquid jet into water pool. An improved jet breakup model is also presented with comparison to the experimental data. Non-boiling liquid jet breakup experiment was conducted and the debris size was analyzed with a new jet breakup model with an emphasis on the role of air entrainment. The predicted debris size with consideration of entrained air showed good agreement with the experimental data

  1. Effect of Air Entrainment on Breakup of Plunging Liquid Jet into Water Pool

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyoungtak; Bang, Kwanghyun [Korea Maritime Univ., Busan (Korea, Republic of)

    2013-05-15

    The steam explosion intensity is largely dependent upon the degree of volumetric fractions of melt droplets and steam in the fuel-coolant mixture. The rate of melt jet breakup and droplet sizes are, therefore, the key physical parameters in the analysis of FCIs. In a recent OECD/NEA international program SERENA, the areas where research may be needed to reduce the level of uncertainties in the code predictions have been identified. The predicted void fractions in the mixture were generally much higher than experimental data and a deficiency in melt jet breakup modeling would be one of the primary causes. In this paper, an extended study of non-boiling liquid jet breakup from the previous jet breakup experiment is reported with an emphasis on the role of air entrainment by plunging liquid jet into water pool. An improved jet breakup model is also presented with comparison to the experimental data. Non-boiling liquid jet breakup experiment was conducted and the debris size was analyzed with a new jet breakup model with an emphasis on the role of air entrainment. The predicted debris size with consideration of entrained air showed good agreement with the experimental data.

  2. Material Properties Governing Co-Current Flame Spread: The Effect of Air Entrainment

    Science.gov (United States)

    Coutin, Mickael; Rangwala, Ali S.; Torero, Jose L.; Buckley, Steven G.

    2003-01-01

    A study on the effects of lateral air entrainment on an upward spreading flame has been conducted. The fuel is a flat PMMA plate of constant length and thickness but variable width. Video images and surface temperatures have allowed establishing the progression of the pyrolyis front and on the flame stand-off distance. These measurements have been incorporated into a theoretical formulation to establish characteristic mass transfer numbers ("B" numbers). The mass transfer number is deemed as a material related parameter that could be used to assess the potential of a material to sustain co-current flame spread. The experimental results show that the theoretical formulation fails to describe heat exchange between the flame and the surface. The discrepancies seem to be associated to lateral air entrainment that lifts the flame off the surface and leads to an over estimation of the local mass transfer number. Particle Image Velocimetry (PIV) measurements are in the process of being acquired. These measurements are intended to provide insight on the effect of air entrainment on the flame stand-off distance. A brief description of the methodology to be followed is presented here.

  3. On the relationship between air entrainment, internal flows and closure mechanism in a ventilated supercavity

    Science.gov (United States)

    Karn, Ashish; Arndt, Roger; Hong, Jiarong

    2015-11-01

    An understanding of underlying physics behind ventilation demand is critical for the operation of underwater vehicles based on ventilated supercavitation for a number of reasons viz. gas entrainment requirements for cavity formation and sustenance. The prior studies on the ventilation demand have reported that the gas entrainment requirement to form a supercavity is substantially larger than that needed to sustain it. This phenomenon, known as ventilation hysteresis, is particularly important from the viewpoint of reduction in gas requirements. However, little physical insights into this phenomenon has yet been provided. In this study, systematic investigations are conducted into ventilation hysteresis with respect to the formation and collapse behaviors of ventilated supercavities. It is suggested that the supercavity formation process is driven by bubble coalescence, whereas its collapse is related to the pressure difference across the supercavity interface at its rear portion. Further, we examine the relationship between ventilation hysteresis, supercavity closures and air entrainment requirements for supercavity formation and sustenance under steady and unsteady flow conditions. These observations are directly related to the internal flows inside the supercavity.

  4. Turbulent hydraulic jumps: Effect of Weber number and Reynolds number on air entrainment and micro-bubble generation

    Science.gov (United States)

    Mortazavi, Milad; Mani, Ali

    2015-11-01

    Air entrainment in breaking waves is a ubiquitous and complex phenomenon. It is the main source of air transfer from atmosphere to the oceans. Furthermore, air entrainment due to ship-induced waves contributes to bubbly flows in ship wakes and also affect their performance. In this study, we consider a turbulent hydraulic jump as a canonical setting to investigate air entrainment due to turbulence-wave interactions. The flow has an inlet Froude number of 2.0, while three different Weber numbers (We = 1820, 729, 292), and two different Reynolds numbers (Re = 11000, 5500) based on the inlet height and inlet velocity are investigated. Air entrainment is shown to be very sensitive to the We number, while Re number has a minor effect. Wave breaking and interface collisions are significantly reduced in the low Weber number cases. As a result, micro-bubble generation is significantly reduced with decreasing Weber number. Vortex shedding events are observed to emerge at the toe of the jump in all of the cases. For high Weber number regimes, shedding of vortices is accompanied by engulfment of air pockets into the jump in a periodic manner, while for lower Webber number regimes such events are significantly suppressed. Reynolds number is shown to have a negligible effect on the air entrainment, wave breaking and micro-bubble generation, contrary to the previous assumptions in other studies. Supported by ONR.

  5. Experimental investigation on the droplet entrainment from interfacial waves in air-water horizontal stratified flow

    International Nuclear Information System (INIS)

    It was mainly due to the fact that droplet entrainment affects the Peak Cladding Temperature (PCT) of the nuclear fuel rod in the Postulated accident conditions of NPP. Recently, droplet entrainment in the horizontally arranged primary piping system for the NPP is of interest because it affects directly the steam binding phenomena in the steam generators. Pan and Hanratty correlation is the only applicable one for the droplet entrainment rate model for horizontal flow. Moreover, there are no efforts for the model development on the basis of the droplet entrainment principal and physics phenomena. More recently, Korea Atomic Energy Research Institute (KAERI) proposed a new mechanistic droplet generation model applicable in the horizontal pipe for the SPACE code. However, constitutive relations in this new model require three model coefficients which have not yet been decided. The purpose of present work is determining three model coefficients by visualization experiment. For these model coefficients, the major physical parameters regarding the interfacial disturbance wave should be measured in this experiments. There are the wave slope, liquid fraction, wave hypotenuse length, wave velocity, wave frequency, and wavelength in the major physical parameters. The experiment was conducted at an air water horizontal rectangular channel with the PIV system. In this study, the experimental conditions were stratified-way flow during the droplet generation. Three coefficients were determined based on several data related to the interfacial wave. Additionally, we manufactured the parallel wire conductance probe to measure the fluctuating water level over time, and compared the wave height measured by the parallel wire conductance probe and image processing from images taken by high speed camera. Experimental investigation was performed for droplet entrainment from phase interface wave in an air-water stratified flow. In the experiments, we measured major physical parameters

  6. Experimental investigation on the droplet entrainment from interfacial waves in air-water horizontal stratified flow

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Byeong Geon; Yun, Byong Jo [Pusan national Univ., Pusan (Korea, Republic of); Kim, Kyoung Du [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-10-15

    It was mainly due to the fact that droplet entrainment affects the Peak Cladding Temperature (PCT) of the nuclear fuel rod in the Postulated accident conditions of NPP. Recently, droplet entrainment in the horizontally arranged primary piping system for the NPP is of interest because it affects directly the steam binding phenomena in the steam generators. Pan and Hanratty correlation is the only applicable one for the droplet entrainment rate model for horizontal flow. Moreover, there are no efforts for the model development on the basis of the droplet entrainment principal and physics phenomena. More recently, Korea Atomic Energy Research Institute (KAERI) proposed a new mechanistic droplet generation model applicable in the horizontal pipe for the SPACE code. However, constitutive relations in this new model require three model coefficients which have not yet been decided. The purpose of present work is determining three model coefficients by visualization experiment. For these model coefficients, the major physical parameters regarding the interfacial disturbance wave should be measured in this experiments. There are the wave slope, liquid fraction, wave hypotenuse length, wave velocity, wave frequency, and wavelength in the major physical parameters. The experiment was conducted at an air water horizontal rectangular channel with the PIV system. In this study, the experimental conditions were stratified-way flow during the droplet generation. Three coefficients were determined based on several data related to the interfacial wave. Additionally, we manufactured the parallel wire conductance probe to measure the fluctuating water level over time, and compared the wave height measured by the parallel wire conductance probe and image processing from images taken by high speed camera. Experimental investigation was performed for droplet entrainment from phase interface wave in an air-water stratified flow. In the experiments, we measured major physical parameters

  7. Air entrainment in transient flows in closed water pipes: a two-layer approach

    CERN Document Server

    Bourdarias, Christian; Gerbi, Stéphane

    2009-01-01

    In this paper, we first construct a model for transient free surface flows that takes into account the air entrainment by a sytem of 4 partial differential equations. We derive it by taking averaged values of gas and fluid velocities on the cross surface flow in the Euler equations (incompressible for the fluid and compressible for the gas). Then, we propose a mathematical kinetic interpretation of this system to finally construct a well-balanced kinetic scheme having the properties of conserving the still water steady state and possesing an energy. Finally, numerical tests on closed uniforms water pipes are performed and discussed.

  8. Inerting characteristics of entrained atomized water on premixed methane-air flame

    Institute of Scientific and Technical Information of China (English)

    Cai Feng; Wang Ping; Zhou Jiebo; Li Chao

    2015-01-01

    A combustion tube experiment platform was designed and used to study the inerting conditions and capacity of entrained atomized water on premixed methane–air flame. The structure of a laminar flame of premixed methane–air gas and the process of interaction between atomized water and flame was recorded, and the rules of combustion velocity, stability and strength rate of laminar flame were experi-mentally studied. The inerting process and mechanism was analyzed, and the characteristics of inerting premixed methane–air gas within explosion limits by atomized water were acquired. The research results show that:for the premixed methane–air gas with a concentration of 7%, the minimum inerting atomized water flux is 20.8 mL/(m2 min);for the premixed methane–air gas with a concentration of 9%, the mini-mum inerting atomized water flux is 32.9 mL/(m2 min);for the premixed methane–air gas with a concen-tration of 11%, the minimum inerting atomized water flux is 44.6 mL/(m2 min). The research results are significant for extinguishing methane flame and inhibiting of methane explosion using atomized water.

  9. Application of Fly Ash from Solid Fuel Combustion in Concrete

    OpenAIRE

    Pedersen, Kim Hougaard; Dam-Johansen, Kim; Jensen, Anker Degn

    2008-01-01

    Application of Fly Ash from Solid Fuel Combustion in Concrete Kim H. Pedersen Abstract Industrial utilization of fly ash from pulverized coal combustion plays an important role in environmentally clean and cost effective power generation. Today, the primary market for fly ash utilization is as pozzolanic additive in the production of concrete. However, the residual carbon in fly ash can adsorb the air entraining admixtures (AEAs) added to enhance air entrainment in concrete in order to increa...

  10. Formation of air-entraining vortices at horizontal intakes without approach flow induced circulation

    Institute of Scientific and Technical Information of China (English)

    Mustafa GOGUS; Mete KOKEN; Ali BAYKARA

    2016-01-01

    The aim of this experimental study is to investigate the effects of hydraulic parameters on the formation of air-entraining vortices at horizontal intake structures without approach flow induced circulation. Six intake pipes of different diameters were tested in the study. The intake pipe to be tested was horizontally mounted to the front side of a large reservoir and then for a wide range of discharges experiments were conducted and critical submergences were detected with adjustable approach channel sidewalls. Empiri- cal equations were derived for the dimensionless critical submergence as a function of the relevant dimensionless parameters. Availa- ble data is also checked for the possible scale effect. Then, these obtained equations were compared with the similar ones in the literature which showed a quite good agreement.

  11. An experimental investigation of the air entrainment in the shutdown cooling system during mid-loop operation

    International Nuclear Information System (INIS)

    An experimental study on the air entrainment phenomena during mid-loop operation has been performed for Ulchin 3 and 4 nuclear power plant (UCN 3 and 4). The UCN 3 and 4 is the standard Combustion Engineering (CE) System 80, two-loop, 2825 MWt pressurized water reactor which is currently under construction in Korea. This study was undertaken by Korea Atomic Energy Research Institute to provide a basis for modification of CE system 80 design which has relatively small mid-loop operating range, and to investigate the impact of the air entrainment on the shutdown cooling pump. A 1/4 scale model test was performed for two shutdown cooling suction nozzle configurations, with and without bellmouth entry, to obtain data relative to air ingestion and vortex formation at the shutdown cooling suction nozzle during mid-loop operation. The test model size was determined based on Froude number corresponding to that which occurs in plants by considering that the Weber number and Reynolds number are large enough to ensure that liquid surface tension and viscosity would not significantly affect the vortex formation. An empirical correlation between the flow rate and the critical submergence was obtained with respect to the Froude number. The impact of the air entrainment of the pump was also investigated to select parameters for plant operators to monitor the onset of air entrainment into shutdown cooling system (SCS). Effects of the bellmouth entry on the critical submergence were also investigated. (author)

  12. Air entrainment and bubble statistics in three-dimensional breaking waves

    Science.gov (United States)

    Deike, Luc; Melville, W. K.; Popinet, Stephane

    2015-11-01

    Wave breaking in the ocean is of fundamental importance in order to quantify wave dissipation and air-sea interaction, including gas and momentum exchange, and to improve parametrizationsfor weather and climate models. Here, we investigate air entrainment and bubble statistics in three-dimensional breaking waves through direct numerical simulations of the two-phase air-water flow using the Open Source solver Gerris. As in previous 2D simulations, the dissipation due to breaking is found to be in good agreement with previous experimental observations and inertial-scaling arguments. For radii larger than the Hinze scale, the bubble size distribution, is found to follow a power law of the radius, r-3and to scale linearly with the time dependent turbulent dissipation rate during the active breaking stages. The time-averaged bubble size distribution is found to follow the same power law of the radius and to scale linearly with the wave dissipation rate per unit length of breaking crest. We propose a phenomenological turbulent bubble break-up model that describes the numerical results and existing experimental results.

  13. Influence of Nozzle geometry on spray shape, particle size, spray velocity and Air entrainment of high pressure Diesel spray

    OpenAIRE

    Hespel, Camille; Blaisot, Jean-Bernard; Margot, Xandra; Patouna, S.; Cessou, Armelle; Lecordier, Bertrand

    2010-01-01

    International audience Air/fuel mixing process in the combustion chamber of Diesel engines plays an important role on the combustion efficiency. This mixing depends on the particle size distribution in the spray, on the local velocity of fuel droplets in the spray and on the air entrainment. Nozzle geometry as well as nozzle internal flow conditions influence many of these spray properties. An experimental study of the influence of the nozzle geometry on these properties has been conducted...

  14. High temperature air-blown woody biomass gasification model for the estimation of an entrained down-flow gasifier.

    Science.gov (United States)

    Kobayashi, Nobusuke; Tanaka, Miku; Piao, Guilin; Kobayashi, Jun; Hatano, Shigenobu; Itaya, Yoshinori; Mori, Shigekatsu

    2009-01-01

    A high temperature air-blown gasification model for woody biomass is developed based on an air-blown gasification experiment. A high temperature air-blown gasification experiment on woody biomass in an entrained down-flow gasifier is carried out, and then the simple gasification model is developed based on the experimental results. In the experiment, air-blown gasification is conducted to demonstrate the behavior of this process. Pulverized wood is used as the gasification fuel, which is injected directly into the entrained down-flow gasifier by the pulverized wood banner. The pulverized wood is sieved through 60 mesh and supplied at rates of 19 and 27kg/h. The oxygen-carbon molar ratio (O/C) is employed as the operational condition instead of the air ratio. The maximum temperature achievable is over 1400K when the O/C is from 1.26 to 1.84. The results show that the gas composition is followed by the CO-shift reaction equilibrium. Therefore, the air-blown gasification model is developed based on the CO-shift reaction equilibrium. The simple gasification model agrees well with the experimental results. From calculations in large-scale units, the cold gas is able to achieve 80% efficiency in the air-blown gasification, when the woody biomass feedrate is over 1000kg/h and input air temperature is 700K.

  15. An analysis of air entrainment into residual heat removal pump during the refueling cavity draindown for Kori Unit 2

    International Nuclear Information System (INIS)

    In 1998, 1999 and 2000, the Kori Unit 2 has experienced the air entrainment and loss of flow in the residual heat removal (RHR) pump during a planned draining of the refueling cavity without the fuel assemblies in the reactor vessel. The water level of the refueling cavity was 1 m above reactor vessel flange when the transients occurred and a similiar event was not known so far in domestic and foreign nuclear power plants. The cause of air entrainment into the RHR pump is analyzed using the RELAP5/MOD3 code in this study. Also, it is qualitatively analyzed the reason why such transients do not occur when fuel assemblies are loaded in reactor vessel

  16. INFLUENCE OF WATER-TO-CEMENT RATIO ON AIR ENTRAILMENT IN PRODUCTION OF NON-AUTOCLAVED FOAM CONCRETE USING TURBULENCE CAVITATION TECHNOLOGY

    Directory of Open Access Journals (Sweden)

    Gorshkov Pavel Vladimirovich

    2012-10-01

    Full Text Available Non-autoclaved foam concrete is an advanced thermal insulation material. Until recently, foam concrete production has been based on separate preparation of foam and solution, followed by their blending in a mixer. The situation changed when high-quality synthetic foaming agents and turbulence cavitation technology appeared on the market. Every model provides a dependence between the foam concrete strength and the water-to-cement ratio. According to the water-cement ratio we can distinguish strong concrete mixtures (with the water-to-cement ratio equal to 0.3…0.4 and ductile ones (with the water-to-cement ratio equal to 0.5…0.7. Strong concrete mixtures are more durable. The lower the water-to-cement ratio, the higher the foam concrete strength. However super-plastic substances cannot be mixed by ordinary turbulent mixers. Foam concrete produced using the turbulence cavitation technology needs air-entraining, its intensity being dependent on several factors. One of the main factors is the amount of free water, if it is insufficient, the mixture will not be porous enough. A researcher needs to identify the optimal water-to-cement ratio based on the water consumption rate. Practical production of prefabricated concrete products and structures has proven that the reduction of the water-to-cement ratio improves the strength of the product. The task is to find the water-to-cement ratio for the foam concrete mixture to be plastic enough for air entraining. An increase in the ratio causes loss in the strength. The ratio shall vary within one hundredth points. Super-plasticizers are an alternative solution.

  17. Potential of ANSYS CFX 12 for the determination of the minimum cover of pump intake nozzles to avoid air entrainment

    International Nuclear Information System (INIS)

    For a reliable and economic pump operation the homogeneous fluid influx is an important parameter. Unfavorable influx conditions cause vibrations, noise development, decrease or breakdown of the delivery rate and increased power consumption. Very often air ingress due to turbulences in the intake region of the pump is causing the disturbances. The authors show that the CFD code ABSYS CFX 12 allows - at least for rotation-free inlet flow - to identify the water surface deformation and to determine the required minimum water cover to avoid air entrainment. Further mesh refinement and improved modeling of the two-phase flow could enhance the quantitative agreement with experimental data.

  18. Entrainment Heat Flux Computed with Lidar and Wavelet Technique in Buenos Aires During Last Chaitén Volcano Eruption

    Directory of Open Access Journals (Sweden)

    Pawelko Ezequiel Eduardo

    2016-01-01

    Full Text Available At Lidar Division of CEILAP (CITEDEF-CONICET a multiwavelength Raman-Rayleigh lidar optimized to measure the atmospheric boundary layer is being operated. This instrument is used for monitoring important aerosol intrusion events in Buenos Aires, such as the arrival of volcanic ashes from the Chaitén volcano eruption on May 2008. That was the first monitoring of volcanic ash with lidar in Argentina. In this event several volcanic ash plumes with high aerosol optical thickness were detected in the free atmosphere, affecting the visibility, surface radiation and therefore, the ABL evolution. In this work, the impact of ashes in entrainment flux ratio is studied. This parameter is obtained from the atmospheric boundary layer height and entrainment zone thickness using algorithms based on covariance wavelet transform.

  19. Entrainment Heat Flux Computed with Lidar and Wavelet Technique in Buenos Aires During Last Chaitén Volcano Eruption

    Science.gov (United States)

    Pawelko, Ezequiel Eduardo; Salvador, Jacobo Omar; Ristori, Pablo Roberto; Pallotta, Juan Vicente; Otero, Lidia Ana; Quel, Eduardo Jaime

    2016-06-01

    At Lidar Division of CEILAP (CITEDEF-CONICET) a multiwavelength Raman-Rayleigh lidar optimized to measure the atmospheric boundary layer is being operated. This instrument is used for monitoring important aerosol intrusion events in Buenos Aires, such as the arrival of volcanic ashes from the Chaitén volcano eruption on May 2008. That was the first monitoring of volcanic ash with lidar in Argentina. In this event several volcanic ash plumes with high aerosol optical thickness were detected in the free atmosphere, affecting the visibility, surface radiation and therefore, the ABL evolution. In this work, the impact of ashes in entrainment flux ratio is studied. This parameter is obtained from the atmospheric boundary layer height and entrainment zone thickness using algorithms based on covariance wavelet transform.

  20. Two-phase numerical study of the flow field formed in water pump sump: influence of air entrainment

    International Nuclear Information System (INIS)

    In a pump sump it is imperative that the amount of non-homogenous flow and entrained air be kept to a minimum. Free air-core vortex occurring at a water-intake pipe is an important problem encountered in hydraulic engineering. These vortices reduce pump performances, may have large effects on the operating conditions and lead to increase plant operating costs.This work is an extended study starting from 2006 in LML and published by ISSA and al. in 2008, 2009 and 2010. Several cases of sump configuration have been numerically investigated using two specific commercial codes and based on the initial geometry proposed by Constantinescu and Patel. Fluent and Star CCM+ codes are used in the previous studies. The results, obtained with a structured mesh, were strongly dependant on main geometrical sump configuration such as the suction pipe position, the submergence of the suction pipe on one hand and the turbulence model on the other hand. Part of the results showed a good agreement with experimental investigations already published. Experiments, conducted in order to select best positions of the suction pipe of a water-intake sump, gave qualitative results concerning flow disturbances in the pump-intake related to sump geometries and position of the pump intake. The purpose of this paper is to reproduce the flow pattern of experiments and to confirm the geometrical parameter that influences the flow structure in such a pump. The numerical model solves the Reynolds averaged Navier-Stokes (RANS) equations and VOF multiphase model. STAR CCM+ with an adapted mesh configuration using hexahedral mesh with prism layer near walls was used. Attempts have been made to calculate two phase unsteady flow for stronger mass flow rates and stronger submergence with low water level in order to be able to capture air entrainment. The results allow the knowledge of some limits of numerical models, of mass flow rates and of submergences for air entrainment. In the validation of this

  1. Experimental study of photocatalytic concrete products for air purification

    Energy Technology Data Exchange (ETDEWEB)

    Huesken, G.; Hunger, M.; Brouwers, H.J.H. [Department of Civil Engineering, Faculty of Engineering Technology, University of Twente, P.O. Box 217, 7500 AE Enschede (Netherlands)

    2009-12-15

    Air quality in inner-city areas is a topic which receives much attention nowadays but in the coming years, the overall interest on this topic will become even bigger. One major concern is caused by the reduction of the limiting values given by the European Council Directive 1999/30/EC [Relating to limit values for sulphur dioxide, nitrogen dioxide and oxides of nitrogen, particulate matter and lead in ambient air. Official Journal of the European Communities 1999, L 163/41-60] and increasing traffic rates especially for diesel powered passenger cars and freight vehicles. A promising approach for solving the problem of nitrogen oxides (NO{sub x}) is the photochemical conversion of nitrogen oxides to low concentrated nitrates due to heterogeneous photocatalytic oxidation (PCO) using titanium dioxide (TiO{sub 2}) as photocatalyst. A variety of products containing TiO{sub 2} are already available on the European market and their working mechanism under laboratory conditions is proven. However, there is still a lack of transforming the experimental results obtained under laboratory conditions to practical applications considering real world conditions. This paper presents the research conducted on photocatalytic concrete products with respect to the evaluation of air-purifying properties. The degradation process of nitric oxide (NO) under laboratory conditions is studied using a test setup for measuring the performance of photocatalytic active concrete products. The test setup uses the UV-A induced degradation of NO and is oriented on the ISO standard ISO 22197-1:2007. Besides the introduction of the test setup, a uniform measuring procedure is presented to the reader which allows for an evaluation and direct comparison of the performance of photocatalytic active concrete products. This kind of direct comparison was not possible so far. Furthermore, the results of a comparative study on varying photocatalytic concrete products of the European market will be discussed

  2. Effect of the aggregate grading on the concrete air permeability

    Directory of Open Access Journals (Sweden)

    Argiz, C.

    2014-09-01

    Full Text Available Great durability problems are being found in concrete structures related to the penetrability of aggressive agents through the concrete (ie. chloride penetration, sulphate attack, carbonation, freezing and thawing, and so on. Air permeability coefficient is used as an effective tool to estimate the potential durability of concrete structures due to its direct relation with the microstructure and the moisture content. This paper discusses the effect of the aggregate grading and water/cement ratio on the air permeability coefficient. An aggregate grading with more sand than coarse aggregates has resulted more beneficial from the point of view of concrete air permeability. This fact can be attributed to a denser skeleton formed by the finer aggregates. With fine aggregates, the higher water/cement ratio, the lower air permeability. However, the contrary was found with coarse aggregates. Overall, a temperature increase from 20 °C to 60 °C during preconditioning led to a Dair increase of 40–80%.Se han encontrado una gran cantidad de problemas de durabilidad de estructuras de hormigón relacionados con la penetración de agentes agresivos externos (es decir, penetración de cloruros, ataque por sulfatos, carbonatación, hielo-deshielo, etc.. El coeficiente de permeabilidad al aire se utiliza como una herramienta eficaz para estimar la durabilidad potencial de las estructuras de hormigón debido a su relación directa con su microestructura y contenido de humedad. Se discute el efecto de la gradación de los áridos y relación agua/cemento en el coeficiente de permeabilidad al aire. Con áridos más finos que gruesos, el resultado es más beneficioso, lo que se atribuye a que la arena forma un esqueleto más denso. Con áridos más finos, al aumentar la relación agua/cemento, disminuye la permeabilidad al aire; pero con áridos más gruesos se ha observado lo contrario. Cuando se pre-acondiciona de 20 °C a 60 °C, se produce un aumento del Dair

  3. Frost resistance of fibre reinforced concrete structures

    DEFF Research Database (Denmark)

    Hansen, Ernst Jan De Place

    1999-01-01

    of 0.4-1% by volume of fibres cannot replace air entrainment in order to secure a frost resistant concrete; the minimum amount of air needed to make the concrete frost resistant is not changed when adding fibres· the amount of air entrainment must be increased when fibres are added to establish......Frost resistance of fibre reinforced concrete with 2.5-4.2% air and 6-9% air (% by volume in fresh concrete) casted in the laboratory and in-situ is compared. Steel fibres with hooked ends (ZP, length 30 mm) and polypropylene fibres (PP, CS, length 12 mm) are applied. It is shown that· addition...

  4. Particle re-entrainment from a powder deposit in an horizontal air flow; Mise en suspension d'une contamination particulaire par ecoulement d'air

    Energy Technology Data Exchange (ETDEWEB)

    Alloul, L.; Witschger, O. [CEA/Saclay, Inst. de Protection et de Surete Nucleaire, IPSN/DPEA/SERAC, Lab. de Physique et Metrologie des Aerosols et du Confinement, 91 - Gif-sur-Yvette (France); Renoux, A. [Paris-12 Univ., Lab. de Physique des Aerosols et de Transfert des Contaminations, 94 - Creteil (France); Le Dur, D. [Aerolab, 91 - Courtaboeuf (France); Monnatte, J. [COGEMA, Branche Combustible et Recyclage, Service Qualite Surete, 78 - Saint-Quentin-en-Yvelines (France)

    2000-07-01

    Particle re-entrainment from surfaces to turbulent air flow is an important subject in many different fields like nuclear safety, environmental air pollution, sediment transport by wind, surface contamination in semiconductor operations. Theoretical and experimental studies have been numerous and cover different aspects of the phenomena. Although a number of theoretical works have been devoted for describing the mechanisms of detachment of primary spherical particles form flat smooth surfaces in a turbulent flow, experimental data are still needed in order to comparison. Moreover, the knowledge of the effect of parameters related to the deposit (monolayer, multilayer, cone-like pile), the powder particles (particle-size distribution, adhesive properties), the surface (roughness,...),the airflow (velocity, acceleration, turbulence) or the environment (humidity,...) is still in an elementary stage. The main objective of our work is to contribute to the understanding and quantification of the parameters that govern the particle re-entrainment from a powder deposit in an turbulent horizontal airflow. Therefore, a new experimental facility called BISE (french acronym for wind tunnel for studying particle re-entrainment by airflow) has been designed and built in our laboratory. (authors)

  5. Controlling Air Content in Concrete That is Being Pumped, A Synthesis Study

    OpenAIRE

    Scholer, Charles F.; Grossman, Jay

    1998-01-01

    Changes in the air content of fresh concrete that is being pumped can occur at a number of places. These locations include the initial loading of the concrete into the pump hopper, as it passes through the pump line, and when it exits the line. This synthesis reviews the findings of recent research studies which deal with air content change in pumped concrete and summarizes methods of reducing air loss caused by handling. Three main mechanisms by which air content is lost in fresh concrete th...

  6. Effect of an entrained air bubble on the acoustics of an ink channel.

    Science.gov (United States)

    Jeurissen, Roger; de Jong, Jos; Reinten, Hans; van den Berg, Marc; Wijshoff, Herman; Versluis, Michel; Lohse, Detlef

    2008-05-01

    Piezo-driven inkjet systems are very sensitive to air entrapment. The entrapped air bubbles grow by rectified diffusion in the ink channel and finally result in nozzle failure. Experimental results on the dynamics of fully grown air bubbles are presented. It is found that the bubble counteracts the pressure buildup necessary for the droplet formation. The channel acoustics and the air bubble dynamics are modeled. For good agreement with the experimental data it is crucial to include the confined geometry into the model: The air bubble acts back on the acoustic field in the channel and thus on its own dynamics. This two-way coupling limits further bubble growth and thus determines the saturation size of the bubble.

  7. Study of air entrainment in high pressure spray: optics diagnostics and application to the Diesel injection; Etude de l'entrainement d'air dans un spray haute pression: diagnostics optiques et application a l'injection diesel

    Energy Technology Data Exchange (ETDEWEB)

    Arbeau, A.

    2004-12-15

    The actual development of the engine must reply to a will of fuel consumption reduction and to norms more and more strict concerning the pollutant emissions. Although the Diesel engines are efficient, the NO{sub x} and particle emissions mainly come from the existence of wealthy fuel zone preventing an optimal combustion. Therefore, the air / fuel mixing preparation, highly controlled by the air entrainment in spray, is essential. In this context, we have developed metrological tools in order to analyse the air entrainment mechanism in a dense spray. The Particle Image Velocimetry (PIV) technique is first applied to a conical spray with an injection pressure less than 100 bars to study the air entrainment in spray. A transfer of the methodologies allows then the characterisation and the understanding of the air entrainment mechanism in high pressure full spray (injection pressure less than 1600 bars) type Diesel one. The influence of injection parameters (injection pressure and back pressure) on the mixing rate is studied. The increase of the injection pressure from 800 to 1600 bars implies an increase of the mixing rate of 60 %. Moreover, the thermodynamic conditions of the ambient air, simulated by the chamber back pressure, widely favours the mixing rate. Actually, this latter increases of 350 % when the chamber back pressure varies from 1 to 7 bars. The experimental results do not follow classical laws of air entrainment in one-phase flow jet with variable density, but are in good agreement with an integral model for air entrainment in an axisymmetric full spray. Finally, the Fluorescence Particle Image Velocimetry (FPIV) is introduced in order to extend the PIV application field in dense two-phase flows. (author)

  8. Free-surface Flow Interface And Air-Entrainment Modelling Using OpenFOAM

    OpenAIRE

    Lopes, Pedro

    2013-01-01

    The use of hydraulic structures to control flooding has a history of long practice within civil engineering infrastructure. Hydraulic structures under turbulent flow conditions frequently involve free surface fl ow and interactions between air and water. This can be observed in different kinds of structures, e.g. gullies, manholes or stepped spillways. In this doctoral program, Computational Fluid Dynamics numerical models will be used to simulate...

  9. A Unified Model Considering Effects of Droplet Break-Up and Air Entrainment at the Initial Stage of Fuel Spray Penetration

    Directory of Open Access Journals (Sweden)

    S. Jafarmadar

    2014-01-01

    Full Text Available This paper proposes a new unified single model that considers droplet break-up and air entrainment impact on three flow regimes (namely, Stokes, Allen, and Newton in the initial stage of fuel spray penetration. Homotopy perturbation method was used to obtain semianalytical solutions of unified single model on diesel fuel’s spray penetration when the influence of air entrainment is small (up to 0.1-0.2 ms after the start of injection. It is demonstrated that the applied analytical method is very straightforward in comparison with existing techniques. Furthermore, it is decidedly effectual in terms of accuracy and rapid convergence. The formulation of the problem is presented in the text as well as the analytical and numerical procedures.

  10. Tensile Bond Between Substrate Concrete and Normal Repairing Mortar under Freeze–Thaw Cycles

    OpenAIRE

    Qian, Ye; Zhang, Dawei; Ueda, Tamon

    2014-01-01

    Concrete patch repair has long been used to repair the damaged concrete structures. In cold regions, freeze– thaw cycle is one of the major damage factors. Not only the material itself is damaged by freeze–thaw cycles, but also the adhesive interface, which is regarded as the weakest part of composite system, degrades under freeze–thaw cycles. Air entraining agent has long been used to increase the freeze–thaw resistance of concrete materials. However, the effect of air entraining agent on th...

  11. Effects of Outside Air Temperature on Movement of Phosphine Gas in Concrete Elevator Bins

    Science.gov (United States)

    Studies that measured the movement and concentration of phosphine gas in upright concrete bins over time indicated that fumigant movement was dictated by air currents, which in turn, were a function of the difference between the average grain temperature and the average outside air temperature durin...

  12. Analysis of transient flows in gasoline direct injection systems: effects on unsteady air entrainment by the spray; Analyse des ecoulements transitoires dans les systemes d'injection directe essence: effets sur l'entrainement d'air instationnaire du spray

    Energy Technology Data Exchange (ETDEWEB)

    Delay, G.

    2005-03-15

    The aim of this study is to determine instantaneous liquid flow rate oscillations effect on non stationary air entrainment of an injector conical spray (Gasoline Direct Injection). The tools we use are either experimental or numerical ones. An instantaneous flow rate determination method is used. It is based on pulsated flows physics and only requires the velocity at the centerline of a pipe mounted just before the injector. So, it is possible to 'rebuild' the instantaneous velocity distributions and then to get the instantaneous liquid flow rate (Laser Doppler Anemometry measurements). A mechanical and hydraulics modeling software (AMESim) is necessary to get injector outlet flow rate. Simulations are validated by both 'rebuilding' method results and common rail pressure measurements. Fluorescent Particle Image Velocimetry (FPIV), suited to dense two -phase flows, is used to measure air flow around and inside the conical spray. Velocity measurements close to the spray frontier are used to compute instantaneous air entrainment. Considering droplets momentum exchange with air and thanks to droplets diameters and liquid velocities measurements at the nozzle exit, a transient air entrainment model is proposed according to FPIV measurements. (author)

  13. Experimental Study on Durability Improvement of Fly Ash Concrete with Durability Improving Admixture

    OpenAIRE

    Quan, Hong-zhu; Kasami, Hideo

    2014-01-01

    In order to improve the durability of fly ash concrete, a series of experimental studies are carried out, where durability improving admixture is used to reduce drying shrinkage and improve freezing-thawing resistance. The effects of durability improving admixture, air content, water-binder ratio, and fly ash replacement ratio on the performance of fly ash concrete are discussed in this paper. The results show that by using durability improving admixture in nonair-entraining fly ash concrete,...

  14. Heterogeneous Photocatalysis Applied to Concrete Pavement for Air Remediation

    Science.gov (United States)

    Ballari, M. M.; Hunger, M.; Hüsken, G.; Brouwers, H. J. H.

    In the present work the degradation of nitrogen oxides (NOx) by concrete paving stones containing TiO2 to be applied in road construction is studied. A kinetic model is proposed to describe the photocatalytic reaction of nitric oxide (NO) in a standard flow laminar photoreactor irradiated with UV lamps. In addition the influence of several parameters that can affect the performance of these stones under outdoor conditions are investigated, such as irradiance, relative humidity and wind speed. The kinetic parameters present in the NO reaction rate are estimated employing experimental data obtained in the photoreactor. The obtained model predictions employing the determined kinetic constants are in good agreement with the experimental results of NO concentration at the reactor outlet.

  15. Numerical study on the heat storing capacity of concrete walls with air cavities

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Z.L. [Dept. of Structural Engineering, Norwegian University of Science and Technology (NTNU), Trondheim (Norway); Wachenfeldt, B.J. [SINTEF Technology and Society, Institute for Architecture and Building Technology, Trondheim (Norway)

    2009-07-15

    Finite element analyses using COMSOL have been carried out to study the heat transfer behavior and storing capacity of concrete walls with air cavities, and to explore the possibility of using one-layer and two-layer one-dimensional models with equivalent thermal conductivity and mass density to represent the effect of concrete walls with air cavities in a building energy simulation. Three typical wall geometries were chosen and both stationary and transient analyses have been carried out. The stationary analyses were performed first to find the equivalent thermal conductivity which was further used in the transient analyses to fit the equivalent mass density. Because of the presence of air cavities the equivalent thermal conductivities are always smaller than the bulk thermal conductivity. However, for the one-layer model an exaggerated equivalent mass density as high as two times the bulk density should be used in order to simulate the heat storing capacity of the concrete walls with air cavities. The values of the fitted equivalent mass density are strongly dependent on the wall thickness. (author)

  16. A Preliminary Study on the Air and Concrete Activation Analysis for RAON ISOL-Bunker

    International Nuclear Information System (INIS)

    There are two radiation analysis field; (i) prompt radiation and (ii) residual radiation. The residual radiation is generated from materials irradiated from the high energy prompt radiation. The dose of the residual radiation is relatively lower than that of the prompt radiation; therefore, the analysis is usually performed after turn-off of the accelerators. In this study, radioactivity analyses were performed to establish the strategy of the activation analysis in ISOL facilities of RAON. To estimate the residual radiation dose calculation, the rigorous-two-step method (R2S) was used with coupling the MCNPX 2.7 and SP-FISPECT-2010 code. In this study, a preliminary study for the air and concrete activation in ISOL-bunker was evaluated using the MCNPX 2.7 and SP-FISPACT-2010 codes. For the air activation, humidity effect was first evaluated; then, the air composition was determined. Also, a calculation procedure of the air activation was established. For the concrete activation, the strategy of dividing the concrete wall was constructed. These results can be used as the reference data to design the ISOL facility with considering radiation safety

  17. THERMAL REGIME OF MASSIVE CONCRETE DAMS WITH AIR CAVITIES IN THE SEVERE CLIMATE

    Directory of Open Access Journals (Sweden)

    Aniskin Nikolay Alekseevich

    2012-12-01

    The thermal regime of the concrete dam with an air cavity can be adjustable by simple structural elements, including a heat-insulating wall and artificial heating of cavities. The required intensity and duration of heating are to be identified. Final conclusions about the most favorable thermal regime pattern will be made upon completion of fundamental calculations of the thermal stress state of the dam to be performed in the next phase of the research.

  18. Properties of concrete containing used engine oil

    Directory of Open Access Journals (Sweden)

    Nasir Shafiq

    2011-07-01

    Full Text Available Since last few years cement replacement materials, industrial by-products and agricultural wastes in concrete production are widely used. It imparts positive environmental effect because the waste materials are not released to the environment. It was reported that the leakage of motor oil onto concrete surfaces in old grinding units increased the resistance such concrete to freezing and thawing, it made to understand that the effect is similar to adding an air-entraining chemical admixture to the concrete. However, the hypothesis is not backed by significant research study and not reported in the available literature. This paper presents results of the experimental study conducted to investigate the effects of used engine oil on properties of fresh and hardened concrete.  With the addition of used engine oil, concrete slump was increased by 18% to 38% and air content by 26% to 58% as compare to the slump of control concrete. Porosity and oxygen permeability of concrete containing used engine oil was also reduced and the compressive strength was obtained approximately same as that of the control mix

  19. Experimental and statistical study of the influence of broken up particles and air content on the compressive strength of concretes

    International Nuclear Information System (INIS)

    Companies in Algeria have restricted budgets devoted to the formulation of concrete. Therefore, very few research studies are interested by the concrete composition in accordance to its purpose. Hence, this work is a part of an approved research program assigned to clarify the impact of certain parameters on the quality of concrete. This experimental program consists of more than 700 cylindrical specimens of 16x32 cm that were made using local materials. Excluding the durability indicators towards the concrete, the compressive strength is the most significant property to be considered (Mounanga et al., 2006). The obtained results concern consistency and content air propertiesof the concrete at fresh state and compressive strength of hardened concrete at 28 days. Thus, the influence of the air content percentage on the concrete consistency is studied. Moreover, the influence of these two parameters on the compressive strength of the hardened concrete is also presented. The experimental results obtained constitute a data bank, which allows comparing through a statistical analysis, the model established by Feret (Baron and Ollivier, 1996) and the results of the tests. (author)

  20. Development of scaling laws of heat removal and CFD assessment in concrete cask air path

    International Nuclear Information System (INIS)

    Highlights: • Vertical concrete cask was studied for PWR spent fuel dry storage. • Scaling laws were derived for facilities between prototype and half-scale model. • Computational Fluid Dynamics analysis was performed with 3D mesh generation. • Thermal radiation was considered with heat conduction and natural convection. - Abstract: This study investigates heat transfer in a concrete cask such as one used at intermediate storage facilities of PWR spent fuels. Sufficient removal of decay heat is necessary not to damage fuel cladding that functions as a radioactive materials barrier. The experimental design parameters were derived in the half-scale model for the assessment of the design analysis methodology including a CFD tool. The scaling methodology was developed to design the half-scale model of the concrete cask in the spent fuel dry storage through scaling analysis. As one of the most important scaling laws, the requirement of similarity was selected for the temperature rise between the inlet and the exit in the air path. Based on the natural circulation in the channel, the scaling law was derived for total canister power maintaining the similarity of the temperature rise. Then, the temperature calculation and the flow analysis were performed in concrete cask facilities for the prototype and the half scale model using Computational Fluid Dynamics code. Through the CFD simulations, the similarity of the temperature rise was demonstrated well between the inlet and the exit, and the exit temperature was well maintained between the prototype and the half scale model. Also the scaling ratios of air mass flow rate and exit velocity obtained by the scaling analysis were in good agreement with those predicted by CFD analysis

  1. Entrainment Concepts Revisited

    NARCIS (Netherlands)

    Roenneberg, Till; Hut, Roelof; Daan, Serge; Merrow, Martha

    2010-01-01

    The traditional approaches to predict entrainment of circadian clocks by light are based on 2 concepts that were never successfully unified: the non-parametric approach assumes that entrainment occurs via discrete daily phase shifts while the parametric approach assumes that entrainment involves cha

  2. Freeze/thaw phenomena in concrete at low temperatures

    DEFF Research Database (Denmark)

    Johannesson, Björn

    2007-01-01

    Freeze/thaw damage in concrete is by general practice concluded to be a problem that can be avoided by using air-entraining agents to develop an air bubble structure in the hardened concrete together with the use of a relatively low water to cement ratio in mix. This fact is true for inner damages......, however, in most part unknown. In this work samples of concrete at different water to cement ratios and air bubble contents subjected to freeze/thaw cycles with the lowest temperature at about -80 oC are investigated. By adopting a novel technique a scanning calorimeter is used to obtain data from which...... of formed ice at different temperatures and the corresponding measured length changes. The development of cracks in the material structure was indicated by an ultra-sonic technique by measuring on the samples before and after the freeze thaw tests. Further the air bubble structure was investigated using...

  3. 混凝土及混凝土结构探讨%Discussion on concrete and concrete structure

    Institute of Scientific and Technical Information of China (English)

    赵润潮

    2012-01-01

    简要介绍了混凝土的历史及其发展方向,从制备混凝土的原材料入手,探讨了混凝土结构强度及耐久性与水、引气剂、钢筋保护层等因素的内在联系,并阐述了防止混凝土碳化、裂缝的具体措施,以促进混凝土施工技术的提高。%With a brief introduce on concrete history and development tendency, starting from raw materials used in manufacturing concrete, the article explores the internal relationship between concrete structure strength and durability and water, air entraining agent and steel protection layer and other factors, and describes specific measures of preventing concrete carbonization and cracks, with a view to guide practice and to improve concrete construction technology.

  4. The effect of form pressure on the air void structure of SCC

    DEFF Research Database (Denmark)

    Jensen, Mikkel Vibæk; Hasholt, Marianne Tange; Geiker, Mette Rica

    2005-01-01

    The high workability of self-compacting concrete (SCC) invites to high casting rates. However, casting walls at high rate may result in large pressure at the bottom of the form and subsequently compression of the air voids. This paper deals with the influence of hydrostatic pressure during setting...... on the air void structure of hardened, air entrained SCC. The subject was examined through laboratory investigations of SCC with two different amounts of air entrainment. The condition in the form was simulated by using containers making it possible to cure concrete under various pressures corresponding...... to the bottom of castings of 0, 2, 4, and 6 meters height. The laboratory investigations were supplemented with data from two full-scale wall castings. The air void structure of the hardened concretes was determined on plane sections. The results indicate that the pressure related changes of the air void...

  5. Entrainment separator performance

    International Nuclear Information System (INIS)

    Clean and dust-loaded ACS entrainment separators mounted upstream of HEPA filters were exposed to a combination of fine water mist and steam at about 700C from one to four hours. In every trial, the ACS entrainment separator prevented measurable deterioration of performance in the following HEPA filter. Droplet size-efficiency evaluation of the ACS entrainment separators showed that, within the accuracy of the measurements, they meet all service requirements and are fully equal to the best separator units available for service on pressurized water reactors

  6. Aerosol entrainment from a sparged non-Newtonian slurry.

    Science.gov (United States)

    Fritz, Brad G

    2006-08-01

    Previous bench-scale experiments have provided data necessary for the development of empirical models that describe aerosol entrainment from bubble bursting. However, previous work has not been extended to non-Newtonian liquid slurries. Design of a waste treatment plant on the Hanford Site in Washington required an evaluation of the applicability of these models outside of their intended range. For this evaluation, aerosol measurements were conducted above an air-sparged mixing tank filled with simulated waste slurry possessing Bingham plastic rheological properties. Three aerosol-size fractions were measured at three sampling heights and for three different sparging rates. The measured entrainment was compared with entrainment models. One model developed based on bench-scale air-water experiments agreed well with measured entrainment. Another model did not agree well with the measured entrainment. It appeared that the source of discrepancy between measured and modeled entrainment stemmed from application beyond the range of data used to develop the model. A possible separation in entrainment coefficients between air-water and steam-water systems was identified. A third entrainment model was adapted to match experimental conditions and fit a posteri to the experimental data, resulting in a modified version that resulted in estimated entrainment rates similar to the first model. PMID:16933643

  7. Increasing jet entrainment, mixing and spreading

    Science.gov (United States)

    Farrington, Robert B.

    1994-01-01

    A free jet of air is disturbed at a frequency that substantially matches natural turbulences in the free jet to increase the entrainment, mixing, and spreading of air by the free jet, for example in a room or other enclosure. The disturbances are created by pulsing the flow of air that creates the free jet at the desired frequency. Such pulsing of the flow of air can be accomplished by sequentially occluding and opening a duct that confines and directs the flow of air, such as by rotating a disk on an axis transverse to the flow of air in the duct.

  8. Influence of Freeze-Thaw Damage on the Steel Corrosion and Bond-Slip Behavior in the Reinforced Concrete

    Directory of Open Access Journals (Sweden)

    Fangzhi Zhu

    2016-01-01

    Full Text Available This paper mainly studies the behavior of steel corrosion in various reinforced concrete under freeze-thaw environment. The influence of thickness of concrete cover is also discussed. Additionally, the bond-slip behavior of the reinforced concrete after suffering the freeze-thaw damage and steel corrosion has also be presented. The results show that the freeze-thaw damage aggravates the steel corrosion in concrete, and the results become more obvious in the concrete after suffering serious freeze-thaw damage. Compared with the ordinary concrete, both air entrained concrete and waterproofing concrete possess better resistance to steel corrosion under the same freeze-thaw environment. Moreover, increasing the thicknesses of concrete cover is also an effective method of improving the resistance to steel corrosion. The bond-slip behavior of reinforced concrete with corroded steel decreases with the increase of freeze-thaw damage, especially for the concrete that suffered high freeze-thaw cycles. Moreover, there exists a good correlation between the parameters of bond-slip and freeze-thaw cycles. The steel corrosion and bond-slip behavior of reinforced concrete should be considered serious under freeze-thaw cycles environment, which significantly impact the durability and safety of concrete structure.

  9. An Observational Study of Entrainment Rate in Deep Convection

    Directory of Open Access Journals (Sweden)

    Xiaohao Guo

    2015-09-01

    Full Text Available This study estimates entrainment rate and investigates its relationships with cloud properties in 156 deep convective clouds based on in-situ aircraft observations during the TOGA-COARE (Tropical Ocean Global Atmosphere Coupled Ocean Atmosphere Response Experiment field campaign over the western Pacific. To the authors’ knowledge, this is the first study on the probability density function of entrainment rate, the relationships between entrainment rate and cloud microphysics, and the effects of dry air sources on the calculated entrainment rate in deep convection from an observational perspective. Results show that the probability density function of entrainment rate can be well fitted by lognormal, gamma or Weibull distribution, with coefficients of determination being 0.82, 0.85 and 0.80, respectively. Entrainment tends to reduce temperature, water vapor content and moist static energy in cloud due to evaporative cooling and dilution. Inspection of the relationships between entrainment rate and microphysical properties reveals a negative correlation between volume-mean radius and entrainment rate, suggesting the potential dominance of homogeneous mechanism in the clouds examined. In addition, entrainment rate and environmental water vapor content show similar tendencies of variation with the distance of the assumed environmental air to the cloud edges. Their variation tendencies are non-monotonic due to the relatively short distance between adjacent clouds.

  10. Prediction of air leakage and aerosol transport through concrete cracks with a fractal based crack morphology model

    Energy Technology Data Exchange (ETDEWEB)

    Bishnoi, L.R., E-mail: lrbishnoi@aerb.gov.in [Siting and Structural Engineering Division, Atomic Energy Regulatory Board, Mumbai 400 094 (India); Vedula, R.P., E-mail: rpv@iitb.ac.in [Mechanical Engineering Department, Indian Institute of Technology, Mumbai 400 076 (India)

    2013-12-15

    Highlights: • A fractal based numerical concrete crack morphology model is presented. • Computational studies conducted for airflow and aerosol transport through cracks. • Results are compared with experimental data and other empirical relations. • Comparative studies demonstrate model effectiveness and versatility of application. - Abstract: Cracks may appear in pressurized concrete containment of a nuclear power plant during a severe accident and provide leak paths for release of radioactive aerosols dispersed in the contained air. In this paper, a fractal based crack morphology model is presented for prediction of air leakage and aerosol transport through cracks in concrete. Airflow field generated in air leakage studies is used for aerosol transport studies with the Lagrangian discrete phase model using CFD code FLUENT. Computational studies conducted with the fractal based model are compared with the experimental data as well as the predictions from empirical relations available in open literature. The comparative studies demonstrate effectiveness of the proposed fractal based model and its versatility for practical applications.

  11. Application of Super Absorbent Polymers (SAP) in Concrete Construction State-of-the-Art Report Prepared by Technical Committee 225-SAP

    CERN Document Server

    Reinhardt, Hans-Wolf

    2012-01-01

    This is the state-of-the-art report prepared by the RILEM TC “Application of Super Absorbent Polymers (SAP) in concrete construction”. It gives a comprehensive overview of the properties of SAP, specific water absorption and desorption behaviour of SAP in fresh and hardening concrete, effects of the SAP addition on rheological properties of fresh concrete, changes of cement paste microstructure and mechanical properties of concrete. Furthermore, the key advantages of using SAP are described in detail: the ability of this material to act as an internal curing agent to mitigate autogenous shrinkage of high-performance concrete, the possibility to use SAP as an alternative to air-entrainment agents in order to increase the frost resistance of concrete, and finally, the benefit of steering the rheology of fresh cement-based materials. The final chapter describes the first existing and numerous prospective applications for this new concrete additive.

  12. Monitoring of Freeze-Thaw Cycles in Concrete Using Embedded Sensors and Ultrasonic Imaging

    OpenAIRE

    Javier Ranz; Sofía Aparicio; Héctor Romero; María Jesús Casati; Miguel Molero; Margarita González

    2014-01-01

    This paper deals with the study of damage produced during freeze-thaw (F-T) cycles using two non-destructive measurement approaches—the first approach devoted to continuous monitoring using embedded sensors during the cycles, and the second one, performing ultrasonic imaging before and after the cycles. Both methodologies have been tested in two different types of concrete specimens, with and without air-entraining agents. Using the first measurement approach, the size and distribution of por...

  13. Study on Properties of Environment-friendly Concrete Containing Large Amount of Industrial by-products

    Science.gov (United States)

    Fujiwara, H.; Maruoka, M.; Sadayama, C.; Nemoto, M.; Yoshikawa, K.; Yamaji, M.

    2015-11-01

    This study aims to reduce CO2 discharged from the cement and concrete industries by effective use of industrial by-products, such as fly ash, blast furnace slag, and so on. In this paper, the properties of concrete containing large amount of industrial by-products and very small amount of alkaline activator including cement or sludge from ready mixed concrete plant are analyzed. As the result, it was confirmed that concretes containing large amount of industrial by-products can achieve sufficient compressive strength. However, these concretes showed poor frost resistance. It was thought that the reason was coarsening of air void system and this caused their poor frost resistance. Therefore, in order to micronize the air void system and improve frost resistance, the combination of air entraining agent and antifoaming agent was applied. By this method, it was confirmed that the frost resistance of some these concrete improved. In this study, other properties of these concretes, such as fresh properties and other durability were evaluated and it was confirmed that these concretes show sufficient properties.

  14. Experimental study of entrainment phenomenon in a trapped vortex combustor

    Institute of Scientific and Technical Information of China (English)

    Zhang Rongchun; Fan Weijun

    2013-01-01

    Trapped vortex combustor (TVC) is an advanced low-pollution gas turbine combustor,with the adoption of staged combustion technique.To achieve low-pollutant emission and better combustion performance,the proportion of the air flow in each combustion zone should be precisely determined in the design of the combustor.Due to the presence of entrainment phenomenon,the total air flow in the cavity zone is difficult to estimate.To overcome the measurement difficulty,this study adopts the indirect measurement approach in the experimental research of entrainment phenomenon in the cavity.In accordance with the measurement principle,a TVC model fueled by methane is designed.Under two experimental conditions,i.e.with and without direct air intake in the cavity,the influence of the mainstream air flow velocity,the air intake velocity in the cavity,the height of inlet channel,the structure of holder and the structural proportion of the cavity on entrainment in the cavity is studied,respectively,through experiment at atmospheric temperature and pressure.The results suggest that the air flow velocity of mainstream,the air intake velocity of the cavity and the structure of the holder exert significant influence on the air entrainment,while the influence of structural proportion of the cavity is comparatively insignificant.The square root of momentum ratio of cavity air to mainstream air could be used to analyze the correlation of the entrainment data.

  15. CO2 Extraction from Ambient Air Using Alkali-Metal Hydroxide Solutions Derived from Concrete Waste and Steel Slag

    Science.gov (United States)

    Stolaroff, J. K.; Lowry, G. V.; Keith, D. W.

    2003-12-01

    To mitigate global climate change, deep reductions in CO2 emissions are required in the coming decades. Carbon sequestration will play a crucial role in this reduction. Early adoption of carbon sequestration in low-cost niche markets will help develop the technology and experience required for large-scale deployment. One such niche may be the use of alkali metals from industrial waste streams to form carbonate minerals, a safe and stable means of sequestering carbon. In this research, the potential of using two industrial waste streams---concrete and steel slag---for sequestering carbon is assessed. The scheme is outlined as follows: Ca and Mg are leached with water from a finely ground bed of steel slag or concrete. The resulting solution is sprayed through air, capturing CO2 and forming solid carbonates, and collected. The feasibility of this scheme is explored with a combination of experiments, theoretical calculations, cost accounting, and literature review. The dissolution kinetics of steel slag and concrete as a function of particle size and pH is examined. In stirred batch reactors, the majority of Ca which dissolved did so within the first hour, yielding between 50 and 250 (mg; Ca)/(g; slag) and between 10 and 30 (mg; Ca)/(g; concrete). The kinetics of dissolution are thus taken to be sufficiently fast to support the type of scheme described above. As proof-of-concept, further experiments were performed where water was dripped slowly through a stagnant column of slag or concrete and collected at the bottom. Leachate Ca concentrations in the range of 15 mM were achieved --- sufficient to support the scheme. Using basic physical principles and numerical methods, the quantity of CO2 captured by falling droplets is estimated. Proportion of water loss and required pumping energy is similarly estimated. The results indicate that sprays are capable of capturing CO2 from the air and that the water and energy requirements are tractable. An example system for

  16. The optimization of concrete mixtures for use in highway applications

    Science.gov (United States)

    Moini, Mohamadreza

    Portland cement concrete is most used commodity in the world after water. Major part of civil and transportation infrastructure including bridges, roadway pavements, dams, and buildings is made of concrete. In addition to this, concrete durability is often of major concerns. In 2013 American Society of Civil Engineers (ASCE) estimated that an annual investment of 170 billion on roads and 20.5 billion for bridges is needed on an annual basis to substantially improve the condition of infrastructure. Same article reports that one-third of America's major roads are in poor or mediocre condition [1]. However, portland cement production is recognized with approximately one cubic meter of carbon dioxide emission. Indeed, the proper and systematic design of concrete mixtures for highway applications is essential as concrete pavements represent up to 60% of interstate highway systems with heavier traffic loads. Combined principles of material science and engineering can provide adequate methods and tools to facilitate the concrete design and improve the existing specifications. In the same manner, the durability must be addressed in the design and enhancement of long-term performance. Concrete used for highway pavement applications has low cement content and can be placed at low slump. However, further reduction of cement content (e.g., versus current specifications of Wisconsin Department of Transportation to 315-338 kg/m 3 (530-570 lb/yd3) for mainstream concrete pavements and 335 kg/m3 (565 lb/yd3) for bridge substructure and superstructures) requires delicate design of the mixture to maintain the expected workability, overall performance, and long-term durability in the field. The design includes, but not limited to optimization of aggregates, supplementary cementitious materials (SCMs), chemical and air-entraining admixtures. This research investigated various theoretical and experimental methods of aggregate optimization applicable for the reduction of cement content

  17. Entrainment of the Neurospora circadian clock

    NARCIS (Netherlands)

    Merrow, M; Boesl, C; Ricken, J; Messerschmitt, M; Goedel, M; Roenneberg, T

    2006-01-01

    Neurospora crassa has been systematically investigated for circadian entrainment behavior. Many aspects of synchronization can be investigated in this simple, cellular system, ranging from systematic entrainment and drivenness to masking. Clock gene expression during entrainment and entrainment with

  18. Experimental Study of Properties of Pervious Concrete used for Bridge Superstructure

    DEFF Research Database (Denmark)

    Lund, Mia Schou Møller; Hansen, Kurt Kielsgaard; Hertz, Kristian Dahl

    2014-01-01

    -Chain Bridges are a new patented bridge technology consisting of a number of Super-Light Deck elements, which are post-tensioned to create an arch bridge used for example for highways. The present study investigates how pervious concrete can be applied as a stabilizing filling materi-al between the arch...... substructure and the wearing course. One pervious concrete mixture contain-ing air entrainment is designed and tested. The tests include investigations of compaction meth-ods, compressive strength, stiffness, frost resistance and permeability....

  19. Effect of Fly Ash on Frost-Resistance and Chloride Ions Diffusion Properties of Marine Concrete

    Institute of Scientific and Technical Information of China (English)

    YANG Wen-wu; QIAN Jue-shi; ZHANG Yi-ying

    2009-01-01

    It is necessary to pay more attention to the durability of concrete undergoing freeze-thaw cycles and seawater attack simultaneously.Investigated are the effects of water-binder ratio,fly ash (FA) contents and air-entraining agent on resistance to frost and chloride diffusion of marine concrete blended with FA in natural seawater.The results show that fly ash does not improve the frost resistance of concrete but can improve its resistance to chloride diffusion by addition of less than 30%.The resistance to frost and chloride diffusion of FA concrete can be improved with the decrease of water-binder ratio,and FA may improve both of them simultaneously only being mixed with air-entraining agent.A ratio (named as R) of the frost-resisting durability factor to chloride diffusion coefficient can be used to evaluate the durability of marine concrete.Scanning electron microscope (SEM) analyses are consistent with the evaluations by the value of R.

  20. Photocatalyticpaving concrete

    Directory of Open Access Journals (Sweden)

    Lyapidevskaya Ol'ga Borisovna

    2014-02-01

    Full Text Available Today bituminous concrete is a conventional paving material. Among its advantages one can name dustlessness and noiselessness, fine wear (up to 1 mm a year and fine maintainability. As the main disadvantages of this material one can name high slipperiness under humidification, low durability and weather resistance. Besides that, during placement of the bituminous concrete a lot of different air pollutants are emitted, which are harmful for environment and human’s health (they are listed in the paper according to the US Environmental Protection Agency materials. As an alternative, one can use cement-concrete pavement, which is in many ways more efficient than the bituminous concrete. It is proposed to enhance environmental performance of the cement-concrete pavement via usage of photocatalysis. The mechanism of different photocatalytic reactions is described in the paper, namely heterogeneous and homogeneous photocatalysis, photo-induces, photoactivated catalysis and catalytical photoreactions. It is pro-posed to use heterogeneous photocatalysis with titanium dioxide as a photocatalyst. The mechanism of photo oxidation of air contaminants, with the usage of titanium dioxide is2described. The paper sets problems, connected with the sensibilization of TiOto thevisible light (it is proposed to use titanium dioxide, doped with the atoms of certain elements to increase its sensibility to the visible light and with the development of a new photocatalytic paving concrete, which will meet the requirements, specified for paving in the climatic and traffic conditions of the Russian Federation.

  1. Research on Deterioration Mechanism of Concrete Materials in an Actual Structure

    Directory of Open Access Journals (Sweden)

    Shiping Zhang

    2014-01-01

    Full Text Available The cause for deterioration of the concrete structure located in severe environment has been explored both in field and in laboratory. Serious cracking and spalling appeared upon surface of the concrete structure soon after the structure was put into service. Both alkali-aggregate reaction and freeze-thaw cycles may result in similar macro visible cracking and spalling. The possibility of alkali-aggregate reaction was excluded by both field survey and lab examination such as chemical analysis, petrographic analysis, and determination of alkali reactivity of aggregates. According to results of freeze-thaw cycles, impermeability testing, and microstructure analysis, it is deduced that the severe environmental conditions plus the relatively inferior frost resistance cause the deterioration of concrete. Usage of air entraining admixture can improve frost resistance and impermeability. Furthermore, new approaches to mitigate the deterioration of concrete used in severe environmental condition are discussed.

  2. 一种外掺新型引气剂的水泥胶砂抗折强度试验研究%A Study on the Bending Strength Test of Cement Mortar Added in a New Type of Air Entraining Agent

    Institute of Scientific and Technical Information of China (English)

    李铁军; 郭红兵

    2014-01-01

    In order to improve the mechanical property of cement mortar, admixtures are pro-posed to be put into cement mortar by adding air-entraining agent separately or mixing air en-training agent and water-reducing agent. The bending strength test of cement mortar has been done. The best model and the optimal dosage of air entraining agent in cement mortar have been determined for its optimal mechanical property. The result shows that the bending strength of cement mortar is significantly greater when air entraining agent and water-reducing agent are mixed. 2 # air-entraining agent has better effect in meeting the requirements of the bending strength of cement mortar.%为了提高水泥胶砂的力学性能,提出在水泥胶砂中掺加外加剂的方法,通过在水泥胶砂中单掺引气剂、复掺引气剂与减水剂两种途径,进行水泥胶砂抗折强度检测试验,对比确定水泥胶砂力学性能最优的引气剂型号及其最佳掺量。结果表明:引气剂与减水剂复掺时水泥胶砂的抗折强度明显大于引气剂单掺时水泥胶砂的抗折强度,2#引气剂最能满足水泥胶砂抗折强度要求。

  3. Timescales of Massive Human Entrainment

    OpenAIRE

    Riccardo Fusaroli; Marcus Perlman; Alan Mislove; Alexandra Paxton; Teenie Matlock; Rick Dale

    2014-01-01

    The past two decades have seen an upsurge of interest in the collective behaviors of complex systems composed of many agents. In this paper, we extend concepts of entrainment to the dynamics of human collective attention. We demonstrate that large scale human entrainment may hold across a number of distinct scales, in an exquisitely time locked fashion. Using a large scale database of human communication data, we analyze and describe three different time scales of human entrainment in electro...

  4. Investigation of the use of fly-ash based autoclaved cellular concrete blocks in coal mines for air duct work. Final report, January 25, 1993--December 31, 1994

    Energy Technology Data Exchange (ETDEWEB)

    Horvath, M.L. [Ohio Edison Co., Akron, OH (United States)

    1995-06-19

    Coal mines are required to provide ventilation to occupied portions of underground mines. Concrete block is used in this process to construct air duct walls. However, normal concrete block is heavy and not easy to work with and eventually fails dramatically after being loaded due to mine ceiling convergence and/or floor heave. Autoclaved cellular concrete block made from (70{plus_minus}%) coal fly ash is lightweight and less rigid when loaded. It is lighter and easier to use than regular concrete block for underground mine applications. It has also been used in surface construction around the world for over 40 years. Ohio Edison along with eight other electric utility companies, the Electric Power Research Institute (EPRI), and North American Cellular Concrete constructed a mobile demonstration plant to produce autoclaved cellular concrete block from utility fly ash. To apply this research in Ohio, Ohio Edison also worked with the Ohio Coal Development Office and CONSOL Inc. to produce autoclaved cellular concrete block not only from coal ash but also from LIMB ash, SNRB ash, and PFBC ash from various clean coal technology projects sponsored by the Ohio Coal Development Office. The purpose of this project was to demonstrate the potential for beneficial use of fly ash and clean coal technology by-products in the production of lightweight block.

  5. Timescales of Massive Human Entrainment

    DEFF Research Database (Denmark)

    Fusaroli, Riccardo; Perlman, Marcus; Mislove, Alan;

    2014-01-01

    The past two decades have seen an upsurge of interest in the collective behaviors of complex systems composed of many agents. In this paper, we extend concepts of entrainment to the dynamics of human collective attention. We demonstrate that large scale human entrainment may hold across a number ...

  6. Air-coupled detection of the S1-ZGV lamb mode in a concrete plate based on backward wave propagation

    Science.gov (United States)

    Bjurström, H.; Ryden, N.

    2013-01-01

    Impact Echo is commonly used to determine thickness of concrete plate like structures. The method is based on the generation and detection of the plate thickness resonance frequency, where the group velocity of the first higher symmetric Lamb mode goes to zero (S1-ZGV). When using air-coupled microphones as receivers it is hard to determine the correct resonance frequency due to low signal to noise ratio. In this study multichannel signal processing is used to identify the S1-ZGV frequency, based on backward wave propagation instead of the conventional amplitude spectrum approach. The original PDF file of this article, as supplied to AIP Publishing, contained some minor font problems within Figures 1, 4, 7, 8, and 9. An updated PDF file using the correct font within those figures was issued on June 3, 2013. There are no other changes to the scientific content.

  7. Timescales of Massive Human Entrainment

    CERN Document Server

    Fusaroli, Riccardo; Mislove, Alan; Paxton, Alexandra; Matlock, Teenie; Dale, Rick

    2014-01-01

    The past two decades have seen an upsurge of interest in the collective behaviors of complex systems composed of many agents. In this paper, we extend concepts of entrainment to the dynamics of human collective attention. We demonstrate that large scale human entrainment may hold across a number of distinct scales, in an exquisitely time locked fashion. Using a large scale database of human communication data, we analyze and describe three different time scales of human entrainment in electronic media. We sought a distinct shared experience that provided a test bed for quantifying large scale human entrainment. We conducted a detailed investigation of the real time unfolding of human entrainment, as expressed by the content and patterns of hundreds of thousands of messages on Twitter, during the 2012 US presidential debates. By time locking these data sources, we quantify the real time impact of the debate on human attention. We show that social behavior covaries second by second to the interactional dynamics...

  8. The optimization of concrete mixtures for use in highway applications

    Science.gov (United States)

    Moini, Mohamadreza

    Portland cement concrete is most used commodity in the world after water. Major part of civil and transportation infrastructure including bridges, roadway pavements, dams, and buildings is made of concrete. In addition to this, concrete durability is often of major concerns. In 2013 American Society of Civil Engineers (ASCE) estimated that an annual investment of 170 billion on roads and 20.5 billion for bridges is needed on an annual basis to substantially improve the condition of infrastructure. Same article reports that one-third of America's major roads are in poor or mediocre condition [1]. However, portland cement production is recognized with approximately one cubic meter of carbon dioxide emission. Indeed, the proper and systematic design of concrete mixtures for highway applications is essential as concrete pavements represent up to 60% of interstate highway systems with heavier traffic loads. Combined principles of material science and engineering can provide adequate methods and tools to facilitate the concrete design and improve the existing specifications. In the same manner, the durability must be addressed in the design and enhancement of long-term performance. Concrete used for highway pavement applications has low cement content and can be placed at low slump. However, further reduction of cement content (e.g., versus current specifications of Wisconsin Department of Transportation to 315-338 kg/m 3 (530-570 lb/yd3) for mainstream concrete pavements and 335 kg/m3 (565 lb/yd3) for bridge substructure and superstructures) requires delicate design of the mixture to maintain the expected workability, overall performance, and long-term durability in the field. The design includes, but not limited to optimization of aggregates, supplementary cementitious materials (SCMs), chemical and air-entraining admixtures. This research investigated various theoretical and experimental methods of aggregate optimization applicable for the reduction of cement content

  9. 不同因素对再生骨料混凝土抗冻性的影响%Effect of Different Factors on Frost Resistance of Recycled Aggregate Concrete

    Institute of Scientific and Technical Information of China (English)

    陈德玉; 刘来宝; 严云; 谭克锋; 刘欢

    2011-01-01

    研究了改性和未改性再生骨料、硅灰及引气剂等因素对C40再生骨料混凝土抗冻性能的影响.结果表明:经300次冻融循环后,与天然骨料混凝土相比,随着再生骨料取代率的增加,再生混凝土的抗冻性有所下降;改性骨料能在一定程度上改善混凝土的抗冻性,有机硅防水剂改性后的再生骨料效果较好;硅灰和引气剂掺加都能较明显地改善再生混凝土的抗冻性.%The influence of modified and unmodified aggregate, silica fume and air-entraining agent on the frost resistance of C40 recycled aggregate concrete has been studied. The results show that the frost resistance of the recycled aggregate concrete with various replacement of recycled aggregate through 300 cycles of freezing and thawing, compared to natural aggregate concrete (control concrete). Moreover, the frost resistance of recycled aggregate concrete falls with the increase of the replacement of recycled aggregate. The frost resistance of recycled aggregate concrete can be improved through either addition of the modified recycled aggregate by organic-silicon or an appropriate amount of silica fume or entrained air agent, and it can be attributed to the improvement of the microstructure of recycled aggregate concrete. Silica fume and air-entraining agent can obviously improve the frost resistance of recycled aggregate concrete.

  10. A case of indoor air pollution of ammonia emitted from concrete in a newly built office in Beijing

    Energy Technology Data Exchange (ETDEWEB)

    Lindgren, Torsten [Department of Medical Sciences/Occupational and Environmental Medicine, Uppsala University, University Hospital, SE-751 85 Uppsala (Sweden)

    2010-03-15

    A case of suspected indoor ammonia contamination from concrete was investigated in an airline company office in Beijing. A standardized questionnaire on indoor environment perceptions, medical symptoms and psychosocial work environment was distributed to all staff, and compared with a reference group of office workers from the same company in Stockholm. Temperature, relative humidity, formaldehyde, volatile organic compounds (VOC), ammonia, and carbon dioxide were measured both in Beijing and Stockholm. In Beijing mould and bacteria were also measured. Totally 95% (N = 14) participated. The Beijing staff reported a higher rate of complaints regarding poor work satisfaction, and work stress as compared to the Stockholm reference group. In the total material (N = 203) the psychosocial environment was related to general symptoms (headache and tiredness) but not odour perception or mucous membrane symptoms. Controlling for age, smoking habits, and psychosocial work environment the Beijing staff had more complaints on unpleasant odour and mucous membrane symptoms. An increased indoor concentration of ammonia (3-6 ppm) and benzene (26.8 {mu}g/m{sup 3}) was measured in the indoor air in the Beijing office, as compared to the office in Stockholm (<0.1 ppm ammonia and 0.4 {mu}g/m{sup 3} benzene). The ammonia contamination in the Beijing office was confirmed, the probable source being additives in the concrete. The ammonia level was well below the Swedish threshold limit values (TLV) (25 ppm). In addition the exposure to benzene, an indicator of traffic exhaust pollution was high both indoors and outdoors in Beijing, possible related to increased levels of odour complaints and mucous membrane irritation. (author)

  11. How Concrete Is Concrete?

    Science.gov (United States)

    Gravemeijer, Koeno

    2011-01-01

    If we want to make something concrete in mathematics education, we are inclined introduce, what we call, "manipulatives", in the form of tactile objects or visual representations. If we want to make something concrete in a everyday-life conversation, we look for an example. In the former, we try to make a concrete model of our own,…

  12. Investigating the Sensitivity of Model Intraseasonal Variability to Minimum Entrainment

    Science.gov (United States)

    Hannah, W. M.; Maloney, E. D.

    2008-12-01

    Previous studies have shown that using a Relaxed Arakawa-Schubert (RAS) convective parameterization with appropriate convective triggers and assumptions about rain re-evaporation produces realistic intraseasonal variability. RAS represents convection with an ensemble of clouds detraining at different heights, each with different entrainment rate, the highest clouds having the lowest entrainment rates. If tropospheric temperature gradients are weak and boundary layer moist static energy is relatively constant, then by limiting the minimum entrainment rate deep convection is suppressed in the presence of dry tropospheric air. This allows moist static energy to accumulate and be discharged during strong intraseasonal convective events, which is consistent with the discharge/recharge paradigm. This study will examine the sensitivity of intra-seasonal variability to changes in minimum entrainment rate in the NCAR-CAM3 with the RAS scheme. Simulations using several minimum entrainment rate thresholds will be investigated. A frequency-wavenumber analysis will show the improvement of the MJO signal as minimum entrainment rate is increased. The spatial and vertical structure of MJO-like disturbances will be examined, including an analysis of the time evolution of vertical humidity distribution for each simulation. Simulated results will be compared to observed MJO events in NCEP-1 reanalysis and CMAP precipitation.

  13. Estimation of convective entrainment properties from a cloud-resolving model simulation during TWP-ICE

    Science.gov (United States)

    Zhang, Guang J.; Wu, Xiaoqing; Zeng, Xiping; Mitovski, Toni

    2015-12-01

    The fractional entrainment rate in convective clouds is an important parameter in current convective parameterization schemes of climate models. In this paper, it is estimated using a 1-km-resolution cloud-resolving model (CRM) simulation of convective clouds from TWP-ICE (the Tropical Warm Pool-International Cloud Experiment). The clouds are divided into different types, characterized by cloud-top heights. The entrainment rates and moist static energy that is entrained or detrained are determined by analyzing the budget of moist static energy for each cloud type. Results show that the entrained air is a mixture of approximately equal amount of cloud air and environmental air, and the detrained air is a mixture of ~80 % of cloud air and 20 % of the air with saturation moist static energy at the environmental temperature. After taking into account the difference in moist static energy between the entrained air and the mean environment, the estimated fractional entrainment rate is much larger than those used in current convective parameterization schemes. High-resolution (100 m) large-eddy simulation of TWP-ICE convection was also analyzed to support the CRM results. It is shown that the characteristics of entrainment rates estimated using both the high-resolution data and CRM-resolution coarse-grained data are similar. For each cloud category, the entrainment rate is high near cloud base and top, but low in the middle of clouds. The entrainment rates are best fitted to the inverse of in-cloud vertical velocity by a second order polynomial.

  14. Estimation of convective entrainment properties from a cloud-resolving model simulation during TWP-ICE

    Science.gov (United States)

    Zhang, Guang J.; Wu, Xiaoqing; Zeng, Xiping; Mitovski, Toni

    2016-10-01

    The fractional entrainment rate in convective clouds is an important parameter in current convective parameterization schemes of climate models. In this paper, it is estimated using a 1-km-resolution cloud-resolving model (CRM) simulation of convective clouds from TWP-ICE (the Tropical Warm Pool-International Cloud Experiment). The clouds are divided into different types, characterized by cloud-top heights. The entrainment rates and moist static energy that is entrained or detrained are determined by analyzing the budget of moist static energy for each cloud type. Results show that the entrained air is a mixture of approximately equal amount of cloud air and environmental air, and the detrained air is a mixture of ~80 % of cloud air and 20 % of the air with saturation moist static energy at the environmental temperature. After taking into account the difference in moist static energy between the entrained air and the mean environment, the estimated fractional entrainment rate is much larger than those used in current convective parameterization schemes. High-resolution (100 m) large-eddy simulation of TWP-ICE convection was also analyzed to support the CRM results. It is shown that the characteristics of entrainment rates estimated using both the high-resolution data and CRM-resolution coarse-grained data are similar. For each cloud category, the entrainment rate is high near cloud base and top, but low in the middle of clouds. The entrainment rates are best fitted to the inverse of in-cloud vertical velocity by a second order polynomial.

  15. Wind profiler mixing depth and entrainment measurements with chemical applications

    Energy Technology Data Exchange (ETDEWEB)

    Angevine, W.M.; Trainer, M.; Parrish, D.D.; Buhr, M.P.; Fehsenfeld, F.C. [NOAA Aeronomy Lab., Boulder, CO (United States); Kok, G.L. [NCAR Research Aviation Facility, Boulder, CO (United States)

    1994-12-31

    Wind profiling radars operating at 915 MHz have been present at a number of regional air quality studies. The profilers can provide a continuous, accurate record of the depth of the convective mixed layer with good time resolution. Profilers also provide information about entrainment at the boundary layer top. Mixing depth data from several days of the Rural Oxidants in the Southern Environment II (ROSE II) study in Alabama in June, 1992 are presented. For several cases, chemical measurements from aircraft and ground-based instruments are shown to correspond to mixing depth and entrainment zone behavior observed by the profiler.

  16. Cloud microphysical effects of turbulent mixing and entrainment

    CERN Document Server

    Kumar, Bipin; Shaw, Raymond A

    2013-01-01

    Turbulent mixing and entrainment at the boundary of a cloud is studied by means of direct numerical simulations that couple the Eulerian description of the turbulent velocity and water vapor fields with a Lagrangian ensemble of cloud water droplets that can grow and shrink by condensation and evaporation, respectively.The focus is on detailed analysis of the relaxation process of the droplet ensemble during the entrainment of subsaturated air, in particular the dependence on turbulence time scales, droplet number density, initial droplet radius and particle inertia. We find that the droplet evolution during the entrainment process is captured best by a phase relaxation time that is based on the droplet number density with respect to the entire simulation domain and the initial droplet radius. Even under conditions favoring homogeneous mixing, the probability density function of supersaturation at droplet locations exhibits initially strong negative skewness, consistent with droplets near the cloud boundary be...

  17. Fourth international conference on fly ash, silica fume, slag, and natural pozzolans in concrete: Supplemental proceedings

    International Nuclear Information System (INIS)

    This report consists of four papers presented at a special session on high volume fly ash (HVFA) concrete. These four papers summarize an EPRI research project currently in progress that is investigating HVFA concretes. This objective of this research is to commercialize the HVFA concrete technology through: (1) an extensive measurement of basic engineering and durability properties; (2) an examination of the binder microstructure and cementation hydration reactions; and (3) technology transfer to industry and the construction community. Overall the data from the project that are summarized in these papers, show that commercial quality structural grade concrete (up to 50 MPa compressive strength at 90 days) can be made from a wide range of fly ashes and cements available throughout the USA. It has been shown in this project that fly ash is a reactive participant with the Portland cement in the cementing process, and also serves as a microaggregate in a multiphase composite binder formed during curing. The properties of the binder were found to significantly influence strength development, elastic modulus, and the stress-strain behavior of HVFA concrete. Overall, the data presented show that regardless of the type of fly ash (from the nine US ashes evaluated) and the two cements used, that air-entrained HVFA concrete exhibits excellent durability in all respects except under application of deicing salts where some surface scaling has been observed in the laboratory

  18. Fourth international conference on fly ash, silica fume, slag, and natural pozzolans in concrete: Supplemental proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Berry, E.E.; Hemmings, R.T.; Zhang, M.H. (Radian Canada, Inc., Mississauga, ON (Canada)); Malhotra, V.M. (Canada Centre for Mineral and Energy Technology, Ottawa, ON (Canada))

    1992-03-01

    This report consists of four papers presented at a special session on high volume fly ash (HVFA) concrete. These four papers summarize an EPRI research project currently in progress that is investigating HVFA concretes. This objective of this research is to commercialize the HVFA concrete technology through: (1) an extensive measurement of basic engineering and durability properties; (2) an examination of the binder microstructure and cementation hydration reactions; and (3) technology transfer to industry and the construction community. Overall the data from the project that are summarized in these papers, show that commercial quality structural grade concrete (up to 50 MPa compressive strength at 90 days) can be made from a wide range of fly ashes and cements available throughout the USA. It has been shown in this project that fly ash is a reactive participant with the Portland cement in the cementing process, and also serves as a microaggregate in a multiphase composite binder formed during curing. The properties of the binder were found to significantly influence strength development, elastic modulus, and the stress-strain behavior of HVFA concrete. Overall, the data presented show that regardless of the type of fly ash (from the nine US ashes evaluated) and the two cements used, that air-entrained HVFA concrete exhibits excellent durability in all respects except under application of deicing salts where some surface scaling has been observed in the laboratory.

  19. Investigation of the Entrainment Phenomenon Using a Scaling Approach

    Science.gov (United States)

    Kishore, Aravind; Ghia, Urmila

    2014-11-01

    Air entrainment is a commonly observed phenomenon; we see it when filling a glass with water from a faucet, in the frothing of the ocean surface, in white water rapids, etc. The focus of our work is the numerical simulation of the entrainment phenomenon associated with laminar plunging jets. With increasing jet velocity, the interfacial cusp formed between the jet and the liquid pool becomes sharper. At a critical jet velocity, entrainment inception occurs, i.e., the interfacial cusp breaks, the interface ruptures, and air is pulled into the liquid pool. We conduct two-fluid simulations using the Volume-Of-Fluid (VOF) methodology. The large range of length scales in the flow presents a major computational challenge. We postulate an approach based on scaling of the underlying physics and this helps alleviate the constraints that the physics poses on the numerical method. The approach is validated using a simple flow configuration - a cylinder rotating at an interface between two fluids. Our simulations capture the sharpening of the interfacial cusp, and the sudden rupture of the interface. The predicted critical entrainment velocities are within 1% of experimental data, thereby providing confidence in the approach. This work was supported by the UC Simulation Center at the University of Cincinnati.

  20. How Concrete is Concrete

    Directory of Open Access Journals (Sweden)

    Koeno Gravemeijer

    2010-07-01

    Full Text Available If we want to make something concrete in mathematics education, we are inclined introduce, what we call, ‘manipulatives’, in the form of tactile objects or visual representations. If we want to make something concrete in a everyday-life conversation, we look for an example. In the former, we try to make a concrete model of our own, abstract, knowledge; in the latter, we try to find an example that the others will be familiar with. This article first looks at the tension between these two different ways of making things concrete. Next another role of manipulatives, will be discussed, namely that of means for scaffolding and communication. In this role, manipulatives may function as means of support in a process that aims at helping students to build on their own thinking while constructing more sophisticated mathematics

  1. Entrained Flow Gasification of Biomass

    DEFF Research Database (Denmark)

    Qin, Ke

    . Biomass gasification experiments were performed in a laboratory-scale atmospheric pressure entrained flow reactor with the aim to investigate the effects of operating parameters and biomass types on syngas products. A wide range of operating parameters was involved: reactor temperature, steam/carbon ratio...... remained nearly unchanged with varying mixing ratio during straw/wood co-gasification, while increased gradually with increasing biomass mixing ratio during biomass/coal co-gasification. A mathematic model of biomass entrained flow gasification was developed. The model included mixing, drying and pyrolysis......, char-gas and soot-gas reactions, detailed gas-phase reactions, and mass and heat transfer. The model could reasonable predict the yields of syngas products obtained in the biomass gasification experiments. Moreover, the simulation results suggest that the soot can be completely converted and thereby...

  2. Bubble size distribution in surface wave breaking entraining process

    Institute of Scientific and Technical Information of China (English)

    HAN; Lei; YUAN; YeLi

    2007-01-01

    From the similarity theorem,an expression of bubble population is derived as a function of the air entrainment rate,the turbulent kinetic energy (TKE) spectrum density and the surface tension.The bubble size spectrum that we obtain has a dependence of a-2.5+nd on the bubble radius,in which nd is positive and dependent on the form of TKE spectrum within the viscous dissipation range.To relate the bubble population with wave parameters,an expression about the air entrainment rate is deduced by introducing two statistical relations to wave breaking.The bubble population vertical distribution is also derived,based on two assumptions from two typical observation results.

  3. THEORETICAL AND EXPERIMENTAL INVESTIGATIONS OF ENTRAINED AND TRANSPORTED CHARACTERISTICS OF SUBMERGED JET

    Institute of Scientific and Technical Information of China (English)

    DONG Zhi-yong; WU Chi-gong; YANG YONG-quan

    2004-01-01

    This paper presents entrainment mechanism,and transported and diffusion characteristics at the point of entry of submerged jet. The profiles of both velocity and concentration within the air-water mixing layer were theoretically deduced. And the comparisons between theoretical values and measured data were made. Results show that the velocity profile within the air-water mixing layer exhibits a form of error function. The concentrations of air entrainment in the internal and external regions of air-water mixing layer correspond to Gaussian distribution.

  4. Research on carbonation of concrete based on air permeability%基于气体渗透性的混凝土碳化性能研究

    Institute of Scientific and Technical Information of China (English)

    费正岳; 李延波; 张士萍

    2014-01-01

    通过研究不同配合比混凝土的碳化深度以及气体渗透系数,发现粉煤灰可以减小碳化,并且碳化后混凝土的气体渗透性也会提高。同时分析了高性能混凝土气体渗透性与碳化性能之间的关系。结果表明混凝土的气体渗透性对碳化深度的控制程度是受粉煤灰掺量的影响,且粉煤灰掺量越高,气体渗透性对碳化的贡献作用越小。%Carbonation depth and air permeability coefficient of concrete samples with different mix proportion were investigated. Results shows that addition of fly ash can decrease carbonation depth.Furthermore,air permeability increased after carbonation.Relation-ship between air permeability and carbonation was also studied.It was found that effect of air permeability on carbonation was impacted by the content of fly ash,and the contribution of air permeability to carbonation decreased with the increase of fly ash.

  5. 混凝土冻融损伤后的吸水特性%Water Absorption Properties of Concrete after Freeze-Thaw Damages

    Institute of Scientific and Technical Information of China (English)

    张鹏; 张连水; 赵铁军; F.H.WITTMANN; E.LEHMANN; 金祖权

    2011-01-01

    Concrete without and with addition of air entrainment have been exposed to freeze-thaw cycles;the influence of frost damages on water absorption properties of concrete was investigated through water absorption test and neutron radiography.Results indicate that by means of neutron radiography the process of water absorption of non-transparent concrete can be observed visually and analyzed quantitatively.For concrete without air entrainment, the dynamic elastic modulus decreases about 14% after only 10 freeze-thaw cycles due to its low frost resistance.Under this condition, water penetration depth into concrete increases by 30%.For the concrete with addition of air entrainment, the dynamic elastic modulus hardly decreases even after 200.freeze-thaw cycles.However, after 200 freeze-thaw cycles part of the surfaces of concrete specimens scale off,which results in higher penetration rate and penetration depth of water.Therefore, the influence of frost damages on water absorption properties of concrete also has to be taken into account when the damage degree of frost action is evaluated, in addition to the decreasing of dynamic elastic modulus.%对掺与未掺引气剂的混凝土进行了冻融破坏,通过吸水试验和中子辐射试验,研究了冻融损伤对掺与未掺引气剂混凝土吸水特性的影响.结果表明,中子成像技术能够实现对非透明性混凝.土材料吸水演进过程的可视化观测和定量分析.未掺引气剂的混凝土其抗冻性较差,在10次冻融循环后动弹模量损失14%的情况下,其水分渗透深度约增30%;掺加引气剂后,即使遭受200次冻融循环,混凝土的整体动弹模量也无明显损失,但200次冻融循环后,混凝土表层出现部分剥落,水分渗透速率及深度均相应增大.在评价混凝土冻融损伤时.除整体动弹模量损失外,还需考虑冻融损伤对混凝土吸水性能的影响.

  6. Bubble entrainment, spray and splashing at hydraulic jumps

    Institute of Scientific and Technical Information of China (English)

    CHANSON Hubert

    2006-01-01

    The sudden transition from a high-velocity, supercritical open channel flow into a slow-moving sub-critical flow is a hydraulic jump. Such a flow is characterised by a sudden rise of the free-surface, with some strong energy dissipation and air entrainment, waves and spray. New two-phase flow measurements were performed in the developing flow region using a large-size facility operating at large Reynolds numbers. The experimental results demonstrated the complexity of the flow with a developing mixing layer in which entrained bubbles are advected in a high shear stress flow. The relationship between bubble count rates and void fractions was non-unique in the shear zone, supporting earlier observations of some form of double diffusion process between momentum and air bubbles. In the upper region, the flow consisted primarily of water drops and packets surrounded by air. Visually significant pray and splashing were significant above the jump roller. The present study is the first comprehensive study detailing the two-phase flow properties of both the bubbly and spray regions of hydraulic jumps, a first step towards understanding the interactions between bubble entrainment and droplet ejection processes.

  7. A model study of mixing and entrainment in the horizontally evolving atmospheric convective boundary layer

    Energy Technology Data Exchange (ETDEWEB)

    Fedorovich, E.; Kaiser, R. [Univ. Karlsruhe, Inst. fuer Hydrologie und Wasserwirtschaft (Germany)

    1997-10-01

    We present results from a parallel wind-tunnel/large-eddy simulation (LES) model study of mixing and entrainment in the atmospheric convective boundary layer (CBL) longitudinally developing over a heated surface. The advection-type entrainment of warmer air from upper turbulence-free layers into the growing CBL has been investigated. Most of numerical and laboratory model studies of the CBL carried out so far dealt with another type of entrainment, namely the non-steady one, regarding the CBL growth as a non-stationary process. In the atmosphere, both types of the CBL development can take place, often being superimposed. (au)

  8. Structural Precast Concrete Handbook

    DEFF Research Database (Denmark)

    Kjærbye, Per Oluf H

    Structural concept for precast concrete systems. Design og precast reinforced concrete components. Design of precast concrete connections. Illustrations on design of precast concrete buildings. Precast concrete assembly....

  9. Drying of concrete. Part II: The drying time of concrete structures

    DEFF Research Database (Denmark)

    Hansen, Kurt Kielsgaard; Christensen, Søren Lolk

    1998-01-01

    The composition of a concrete mix has a significant influence on the drying time to reach a given relative humidity in the concrete pores. Knowledge of the influence on the drying of a specific component in the concrete makes it possible to design a concrete mix having a predetermined drying time....... In the paper the effects of the air content and the silica fume content on the drying time are investigated on two concrete mixes having different water/cement ratios. One concrete represents a normal concrete and the other represents a selfdesiccation concrete.......The composition of a concrete mix has a significant influence on the drying time to reach a given relative humidity in the concrete pores. Knowledge of the influence on the drying of a specific component in the concrete makes it possible to design a concrete mix having a predetermined drying time...

  10. Quantifying entrainment in pyroclastic density currents from the Tungurahua eruption, Ecuador: Integrating field proxies with numerical simulations

    Science.gov (United States)

    Benage, M. C.; Dufek, J.; Mothes, P. A.

    2016-07-01

    The entrainment of air into pyroclastic density currents (PDCs) impacts the dynamics and thermal history of these highly mobile currents. However, direct measurement of entrainment in PDCs is hampered due to hazardous conditions and opaqueness of these flows. We combine three-dimensional multiphase Eulerian-Eulerian-Lagrangian calculations with proxies of thermal conditions preserved in deposits to quantify air entrainment in PDCs at Tungurahua volcano, Ecuador. We conclude that small-volume PDCs develop a particle concentration gradient that results in disparate thermal characteristics for the concentrated bed load (>600 to ~800 K) and the overlying dilute suspended load (~300-600 K). The dilute suspended load has effective entrainment coefficients 2-3 times larger than the bed load. This investigation reveals a dichotomy in entrainment and thermal history between two regions in the current and provides a mechanism to interpret the depositional thermal characteristics of small-volume but frequently occurring PDCs.

  11. Pervious Concrete

    OpenAIRE

    Torsvik, Øyvind André Hoff

    2011-01-01

    Pervious concrete is a type of concrete with little or no fines which give a large void. This enables high permeability and because of this it enables water to percolate through the concrete. Pervious concrete have been used in many years both as pavement material and on several other applications in the U.S and in other countries in Western Europe. In Norway pervious concrete is not currently in use. This thesis aims to investigate if pervious concrete can withstand the harsh Norwegian clima...

  12. Glazed Concrete

    DEFF Research Database (Denmark)

    Bache, Anja Margrethe

    2010-01-01

    Why glazed concrete? Concrete hardens and finds its strength at room temperature whereas clay products must first be fired before they achieve this strength. They are stronger and three times as durable as clay products, which is a weighty reason for choosing concrete.5 Another reason, which....... If this succeeds, it will be possible to manufacture thin, large-scale glazed concrete panels comparable in size to concrete sandwich construction and larger which, with or without back-casting, can work as load-bearing construction elements....

  13. Concrete Hinges

    DEFF Research Database (Denmark)

    Halding, Philip Skov; Hertz, Kristian Dahl; Schmidt, Jacob Wittrup

    2014-01-01

    In the first part of the 20th century concrete hinges developed by Freyssinet and Mesnager were widely tested and implemented in concrete structures. The concrete hinges were used a great deal in closed-spandrel arch bridges. Since such a bridge type has not been competitive for the past 40 years......, the research in concrete hinges has not evolved significantly in that period. But introducing a new state-of-the-art concrete arch bridge solution (Pearl-Chain arches invented at the Technical University of Denmark) creates a necessity of a concrete hinge research based on modern standards. Back when research...... in concrete hinges was more common different designs were proposed for the geometry and reinforcement. Previous research focused on fatigue, multi-axial stresses around the hinge throat, and the relation between rotation- and moment. But many different test-setups were proposed by different researchers...

  14. Fracture energy evolution of two concretes resistant to the action of freeze-thaw cycles

    Directory of Open Access Journals (Sweden)

    Enfedaque, A.

    2014-03-01

    Full Text Available The current standards that regulate use of structural concrete have highlighted the durability of concrete. However, how the fracture energy of concrete evolves under the action of freeze-thaw cycles is not well known. The fracture energy of two types of concrete, one with an air-entraining additive and the other with silica fume addition, is studied after four, 14 and 28 freeze-thaw cycles. The results obtained show that the concrete with an air-entraining additive was undamaged and that fracture energy grew slightly. In addition to this, they also showed that the concrete with silica fume addition suffered severe surface scaling and its fracture energy changed due to the greater fracture areas generated.La actual normativa que rige el empleo de hormigón estructural ha puesto enfásis en la durabilidad del hormigón. Sin embargo, no se conoce cómo evoluciona la energía de fractura del hormigón sometido a ciclos hielo- deshielo, lo cual es de vital importancia para asegurar la durabilidad y el correcto comportamiento mecánico de las estructuras de hormigón en entornos con heladas durante su vida útil. Se ha estudiado la evolución de la energía de fractura de un hormigón con aireante y de un hormigón con humo de sílice después de 4, 14 y 28 ciclos hielo-deshielo realizando ensayos de fractura. Los resultados muestran cómo el hormigón con aireante no sufre daño por los ciclos hielo-deshielo y cómo la energía de fractura del mismo aumenta ligeramente. El hormigón con humo de sílice se daña por los ciclos hielo-deshielo y reduce su energía de fractura al aumentar el area fracturada.

  15. Electrical pulses protect concrete

    NARCIS (Netherlands)

    Van Kasteren, J.

    2006-01-01

    Even concrete is not as hard as it looks. Sea water, salt on icy roads, and indirectly even carbon dioxide from the air can corrode the steel of the reinforcing bars and so threaten the strength and integrity of a bridge pier, jetty, or viaduct. Dessi Koleva, a chemical engineer from Bulgaria, spent

  16. Conceptual design of passive containment cooling system with air holdup tanks in the concrete containment of improved APR+

    Energy Technology Data Exchange (ETDEWEB)

    Jeon, Byong Guk; NO, Hee Cheon, E-mail: hcno@kaist.ac.kr

    2014-02-15

    Highlights: • Conceptual design of passive containment cooling system (PCCS) based on APR+ is proposed. • Decay heat removal rate is to be maximized by introducing air holdup tanks (AHT). • Only air is transported into the AHT decreasing air mass fraction near HXs inside containment and increasing heat transfer rates. • Large AHT volume gives significantly higher heat removal rate. • External HXs have merits over in-tube HXs for long term cooling. - Abstract: The accident of the Fukushima nuclear power plant emphasized passive systems against prolonged station blackout. This paper aims at conceptual design of passive containment cooling system (PCCS) based on APR+, an advanced PWR developed in Korea with passive auxiliary feedwater system (PAFS). In the design, decay heat removal rate is to be maximized by introducing air holdup tanks (AHT). The AHT is an isolated space disposed above IRWST and is connected to the containment free space by vent lines through IRWST water and PAFS heat exchangers (HXs), where steam generated by decay heat is condensed. Since a lot of steam is condensed through in-tube HXs and IRWST water, air is mainly transported into the AHT decreasing air mass fraction near HXs inside containment and increasing heat transfer rates. Several design options (AHT volume, flow distribution in vent lines, HX types) are evaluated via scoping analysis. The scoping analysis had proved that AHT (>10% containment volume) decreased the required number of PCCS HXs to be installed less than a half, failure of valves caused marginal increase in HXs to be installed, and external HXs had merits over in-tube HXs for long term cooling.

  17. Washing of the AN-107 entrained solids

    International Nuclear Information System (INIS)

    This report describes the results of a test conducted by Battelle to assess the effects of inhibited water washing on the composition of the entrained solids in the diluted AN-107 low-activity waste (LAW) sample. The objective of this work was to gather data on the solubility of the AN-107 entrained solids in 0.01 M NaOH, so that BNFL can evaluate whether these solids require caustic leaching

  18. Study on the impact for bending properities of concrete under different initial defections%混凝土初始缺陷对其弯曲性能的影响研究

    Institute of Scientific and Technical Information of China (English)

    张云发; 章青; 袁锋华; 刘学聪

    2015-01-01

    在同一种配合比混凝土试件中掺入4种不同含量的引气剂,以模拟混凝土的初始缺陷,并在CMT-100微机控制电子万能试验机上进行混凝土试件的四点弯曲试验,测出了混凝土弯曲过程的应力-应变曲线,研究了不同缺陷含量对混凝土的抗弯强度、变形特性和损伤特性的影响。试验结果表明:随着掺入引气剂含量的增加,混凝土的应力-应变曲线逐渐平缓,混凝土内部的初始损伤相应增加,其抗弯强度均随之降低,而峰值应变基本保持不变。%Initial defections were simulated through mixing different quantities of air entraining agent into four test samples of the same concrete,and then four-point bending tests of plain concrete specimens were carried out by using a static-dynamic test machine. The relation of strain-strain curves of the concrete were obtained,and the effects of different initial defections on bending strengths,strain-strain curves and damage behaviors of concrete were investigated. It was found that the initial damage of concrete were increasing and the strain-strain curves were began to flatten;the bending strengths of concrete were decreased with the increasing quantities of air en-training agent,but the peak strains remained unchanged.

  19. Simulation study on factors influencing the entrainment behavior of liquid steel as bubbles pass through the steel/slag interface

    Institute of Scientific and Technical Information of China (English)

    Xiang Li; Yan-ping Bao; Min Wang; Lu Lin

    2016-01-01

    In this study, a water/silicone oil interface was used to simulate the steel/slag interface in a converter. A high-speed camera was used to record the entrainment process of droplets when air bubbles were passed through the water/silicone oil interface. Motion parameters of the bubbles and droplets were obtained using particle kinematic analysis software, and the entrainment rate of the droplets was calculated. It was found that the entrainment rate decreased from 29.5% to 0 when the viscosity of the silicone oil was increased from 60 mPa·s to 820 mPa·s in the case of bubbles with a 5 mm equivalent diameter passing through the water/silicone oil interface. The results indicate that in-creasing the viscosity of the silicone oil is conducive to reducing the entrainment rate. The entrainment rate increased from 0 to 136.3% in the case of silicone oil with a viscosity of 60 mPa·s when the equivalent diameter of the bubbles was increased from 3 mm to 7 mm. We there-fore conclude that small bubbles are also conductive to reducing the entrainment rate. The force analysis results for the water column indicate that the entrainment rate of droplets is affected by the velocity of the bubble passing through the water/silicone oil interface and that the en-trainment rate decreases with the bubble velocity.

  20. NANOMODIFIED CONCRETE

    Directory of Open Access Journals (Sweden)

    B. M. Khroustalev

    2015-01-01

    Full Text Available One of the main directions in construction material science is the development of  next generation concrete that is ultra-dense, high-strength, ultra-porous, high heat efficient, extra corrosion-resistant. Selection of such direction is caused by extreme operational impacts on the concrete, namely: continuously increasing load on the concrete and various dynamics of such loads; the necessity in operation of concrete products in a wide temperature range and their exposure to various chemical and physical effects.The next generation concrete represents high-tech concrete mixtures with additives that takes on and retain the required properties when hardening and being used under any operational conditions. A differential characteristic of the next generation concrete is its complexity that presumes usage of various mineral dispersed components, two- and three fractional fine and coarse aggregates, complex chemical additives, combinations of polymer and iron reinforcement.Design strength and performance properties level of the next generation concrete is achieved by high-quality selection of the composition, proper selection of manufacturing techniques, concrete curing, bringing the quality of concrete items to the required level of technical condition during the operational phase. However, directed formation of its structure is necessary in order to obtain high-tech concrete.Along with the traditional methods for regulation of the next generation concrete structure, modification of concrete while using silica nanoparticles is also considered as a perspective one because the concrete patterning occurs due to introduction of a binder in a mineral matrix. Due to this it is possible to obtain nano-modified materials with completely new properties.The main problem with the creation of nano-modified concrete is a uniform distribution of nano-materials in the volume of the cement matrix which is particularly important in the cases of adding a modifier in

  1. Entrainment, Drizzle, and Cloud Albedo

    Science.gov (United States)

    Ackerman, A. S.; Kirkpatrick, J. P.; Stevens, D. E.; Toon, O. B.

    2004-01-01

    Increased aerosol and hence droplet concentrations in polluted clouds are expected to inhibit precipitation and thereby increase cloud water, leading to more reflective clouds that partially offset global warming. Yet polluted clouds are not generally observed to hold more water. Much of the uncertainty regarding the indirect aerosol effect stems from inadequate understanding of such changes in cloud water. Detailed simulations show that the relative humidity of air overlying stratocumulus is a leading factor determining whether cloud water increases or decreases when precipitation is suppressed. When the overlying air is dry, cloud water can decrease as droplet concentrations increase.

  2. Analazing the impact behavior of porous concrete

    NARCIS (Netherlands)

    Agar Ozbek, A.S.; Weerheijm, J.

    2014-01-01

    Porous concrete is a special type of cementitious material incorporating a high amount of meso-size air pores that makes its characteristics markedly different from normal concrete. Therefore, it is being investigated for various applications, aiming to benefit from the presence of the air voids in

  3. INFLUENCE OF WATER-TO-CEMENT RATIO ON AIR ENTRAILMENT IN PRODUCTION OF NON-AUTOCLAVED FOAM CONCRETE USING TURBULENCE CAVITATION TECHNOLOGY

    OpenAIRE

    Gorshkov Pavel Vladimirovich

    2012-01-01

    Non-autoclaved foam concrete is an advanced thermal insulation material. Until recently, foam concrete production has been based on separate preparation of foam and solution, followed by their blending in a mixer. The situation changed when high-quality synthetic foaming agents and turbulence cavitation technology appeared on the market. Every model provides a dependence between the foam concrete strength and the water-to-cement ratio. According to the water-cement ratio we can distinguish st...

  4. On dust entrainment in photoevaporative winds

    Science.gov (United States)

    Hutchison, Mark A.; Price, Daniel J.; Laibe, Guillaume; Maddison, Sarah T.

    2016-09-01

    We investigate dust entrainment by photoevaporative winds in protoplanetary discs using dusty smoothed particle hydrodynamics. We use unequal-mass particles to resolve more than five orders of magnitude in disc/outflow density and a one-fluid formulation to efficiently simulate an equivalent magnitude range in drag stopping time. We find that only micron-sized dust grains and smaller can be entrained in extreme-UV radiation-driven winds. The maximum grain size is set by dust settling in the disc rather than aerodynamic drag in the wind. More generally, there is a linear relationship between the base flow density and the maximum entrainable grain size in the wind. A pileup of micron-sized dust grains can occur in the upper atmosphere at critical radii in the disc as grains decouple from the low-density wind. Entrainment is a strong function of location in the disc, resulting in a size sorting of grains in the outflow - the largest grain being carried out between 10 and 20 au. The peak dust density for each grain size occurs at the inner edge of its own entrainment region.

  5. Nonphotic entrainment of the human circadian pacemaker

    Science.gov (United States)

    Klerman, E. B.; Rimmer, D. W.; Dijk, D. J.; Kronauer, R. E.; Rizzo, J. F. 3rd; Czeisler, C. A.

    1998-01-01

    In organisms as diverse as single-celled algae and humans, light is the primary stimulus mediating entrainment of the circadian biological clock. Reports that some totally blind individuals appear entrained to the 24-h day have suggested that nonphotic stimuli may also be effective circadian synchronizers in humans, although the nonphotic stimuli are probably comparatively weak synchronizers, because the circadian rhythms of many totally blind individuals "free run" even when they maintain a 24-h activity-rest schedule. To investigate entrainment by nonphotic synchronizers, we studied the endogenous circadian melatonin and core body temperature rhythms of 15 totally blind subjects who lacked conscious light perception and exhibited no suppression of plasma melatonin in response to ocular bright-light exposure. Nine of these fifteen blind individuals were able to maintain synchronization to the 24-h day, albeit often at an atypical phase angle of entrainment. Nonphotic stimuli also synchronized the endogenous circadian rhythms of a totally blind individual to a non-24-h schedule while living in constant near darkness. We conclude that nonphotic stimuli can entrain the human circadian pacemaker in some individuals lacking ocular circadian photoreception.

  6. Entrainment and the cranial rhythmic impulse.

    Science.gov (United States)

    McPartland, J M; Mein, E A

    1997-01-01

    Entrainment is the integration or harmonization of oscillators. All organisms pulsate with myriad electrical and mechanical rhythms. Many of these rhythms emanate from synchronized pulsating cells (eg, pacemaker cells, cortical neurons). The cranial rhythmic impulse is an oscillation recognized by many bodywork practitioners, but the functional origin of this impulse remains uncertain. We propose that the cranial rhythmic impulse is the palpable perception of entrainment, a harmonic frequency that incorporates the rhythms of multiple biological oscillators. It is derived primarily from signals between the sympathetic and parasympathetic nervous systems. Entrainment also arises between organisms. The harmonizing of coupled oscillators into a single, dominant frequency is called frequency-selective entrainment. We propose that this phenomenon is the modus operandi of practitioners who use the cranial rhythmic impulse in craniosacral treatment. Dominant entrainment is enhanced by "centering," a technique practiced by many healers, for example, practitioners of Chinese, Tibetan, and Ayurvedic medicine. We explore the connections between centering, the cranial rhythmic impulse, and craniosacral treatment. PMID:8997803

  7. Concrete products

    Energy Technology Data Exchange (ETDEWEB)

    Anon

    2002-01-01

    Increased strength and durability in concrete products can be achieved through the addition of fly ash during the manufacturing process. The properties of concrete are enhanced by fly ash. The benefits include cost and the environment. Fly ash is normally defined as finely divided residue resulting from the combustion of pulverized coal, carried from the combustion chamber to the furnace by exhaust gas. The main applications of fly ash in concrete products are ready mix concrete, bridge decks and support footing, precast structures, blocks and bricks, and pipes. The Canadian Standards Association (CSA) has published standards to ensure that the desired physical properties of the concrete are achieved and the standards are found in CSA A23.1, detailing the engineering materials and mix proportions. The type of fly ash to be used for specific properties is important. Finishing and curing operations must be performed with care. The free lime generated by cement hydration reacts with fly ash, forming additional calcium silicate hydrate. Permeability of the concrete is reduced since the calcium silicate hydrate fills the void resulting from the cement pour. Some of the benefits to be derived from fly ash in concrete are: water reduction, improved workability, high ultimate strength, improved pumpability, and reduced heat of hydration. In addition, the life cycle costs are lower, and great strength is obtained. An environmental benefit results from the reduction of natural resource consumption.

  8. 活性掺合料再生混凝土抗冻性能试验%Experiment on the frost resistance of active admixture recycled concrete

    Institute of Scientific and Technical Information of China (English)

    陈爱玖; 孙晓培; 张敏; 王静

    2014-01-01

    The concrete engineering is worst affected by frost damage in north area of China.analysis of five factors (slag powder,fly ash,air-entraining agent,polypropylene fiber and recycled coarse aggregate) on the influence law of recycled concrete frost resistance by orthogonal test.Find out the most important influence factors on relative loss modulus and compressive strength of recycled concrete ,by compare the recycled concrete freeze-thaw cycle 0 times and 200 times,loss modulus and compressive strength,then analysis of the mech-anism of recycled concrete.%我国北方地区的混凝土工程是受冻害最严重的地区。采用正交试验法分析矿渣粉、粉煤灰、引气剂、聚丙烯纤维和再生粗骨料对再生混凝土抗冻性的影响规律,即:对比再生混凝土冻融循环次数0、200次的质量损失、相对动弹模量、抗压强度,找出对再生混凝土的相对动弹模量和抗压强度影响最大的因素,并对影响机理进行分析。

  9. Entrainment and mixing in stratified shear flows

    Science.gov (United States)

    Strang, Eric James

    1997-12-01

    The results of a laboratory experiment designed to study turbulent entrainment at sheared density interfaces are described. In the parameter ranges investigated the entrainment problem is mainly determined by two parameters, the bulk Richardson number RiB = /Delta bD//Delta U2 and the frequency ratio fN = ND//Delta U. When RiB > 1.5, the buoyancy effects play a governing role, whence interfacial instabilities locally mix heavy and light fluids. The nature of interfacial instabilities is governed by RiB or a related quantity, the mean local gradient Richardson number /overline [Ri]g=/overline [N(z)]2/(/overline[/partial u//partial z)]2, where N(z) is the Brunt-Vaisala frequency local to the interface. When RiB Rif ~ 0.15-0.4) when RiB≃ 3-5. At RiB~ 5, the K-H regime transitions to a new regime wherein the interface is dominated by interfacial/Holmboe wave instabilities. Here, the entrainment rates are much smaller and there is no evidence of interfacial swelling. In the K-H regime, the swelling of the interface introduces its own forcing time scale, which excites and radiates internal waves in the lower layer if it is continuously stratified. Consequently, the amount of energy available for entrainment decreases and, depending on fN, the entrainment velocities in the linearly stratified case can be substantially smaller than the two-layer case (up to 50%). In the interfacial/Holmboe wave breaking regime, internal wave radiation to the bottom layer is much smaller, so as the difference in entrainment rates of the two-layer and linearly stratified cases. Furthermore, when RiB > 5, the entrainment interface shows an approximate balance between the production of turbulent kinetic energy, its dissipation and the buoyancy flux. When entrainment is active RiB/le 5/ (/overline [Ri]g/le 1), the eddy diffusivity for mass Kρ was determined to be approximately 0.3/ cm2[/cdot]sec-1. For RiB > 5,/ Kρ attenuated dramatically. At low RiB/ ([<]5), the eddy diffusivity for

  10. Monitoring of freeze-thaw cycles in concrete using embedded sensors and ultrasonic imaging.

    Science.gov (United States)

    Ranz, Javier; Aparicio, Sofía; Romero, Héctor; Casati, María Jesús; Molero, Miguel; González, Margarita

    2014-01-01

    This paper deals with the study of damage produced during freeze-thaw (F-T) cycles using two non-destructive measurement approaches-the first approach devoted to continuous monitoring using embedded sensors during the cycles, and the second one, performing ultrasonic imaging before and after the cycles. Both methodologies have been tested in two different types of concrete specimens, with and without air-entraining agents. Using the first measurement approach, the size and distribution of pores were estimated using a thermoporometrical model and continuous measurements of temperature and ultrasonic velocity along cycles. These estimates have been compared with the results obtained using mercury porosimetry testing. In the second approach, the damage due to F-T cycles has been evaluated by automated ultrasonic transmission and pulse-echo inspections made before and after the cycles. With these inspections the variations in the dimensions, velocity and attenuation caused by the accelerated F-T cycles were determined. PMID:24481231

  11. Monitoring of Freeze-Thaw Cycles in Concrete Using Embedded Sensors and Ultrasonic Imaging

    Directory of Open Access Journals (Sweden)

    Javier Ranz

    2014-01-01

    Full Text Available This paper deals with the study of damage produced during freeze-thaw (F-T cycles using two non-destructive measurement approaches—the first approach devoted to continuous monitoring using embedded sensors during the cycles, and the second one, performing ultrasonic imaging before and after the cycles. Both methodologies have been tested in two different types of concrete specimens, with and without air-entraining agents. Using the first measurement approach, the size and distribution of pores were estimated using a thermoporometrical model and continuous measurements of temperature and ultrasonic velocity along cycles. These estimates have been compared with the results obtained using mercury porosimetry testing. In the second approach, the damage due to F-T cycles has been evaluated by automated ultrasonic transmission and pulse-echo inspections made before and after the cycles. With these inspections the variations in the dimensions, velocity and attenuation caused by the accelerated F-T cycles were determined.

  12. An ongoing investigation on modeling the strength properties of water-entrained cement-based materials

    DEFF Research Database (Denmark)

    Esteves, L.P.

    2012-01-01

    Water-entrained cement based materials by superabsorbent polymers is a concept that was introduced in the research agenda about a decade ago. However, a recent application in the production of high performance concrete revealed potential weaknesses when the proportioning of this intelligent...... material is not well performed, raising doubts among both academic and industrial society about the usability of superabsorbent polymers in cement-based materials. This work constitutes the baseline tentatively to be used on modeling the compressive strength of SF-modified water-entrained cement......-based materials. Beyond the discussion of whether or not the introduction of superabsorbent polymers leads to a strength reduction, this paper uses both experimental and theoretical background to separate the effect of SAP in both pore structure and internal relative humidity and the effect from the active...

  13. Observational estimates of detrainment and entrainment in non-precipitating shallow cumulus

    Science.gov (United States)

    Norgren, M. S.; Small, J. D.; Jonsson, H. H.; Chuang, P. Y.

    2016-01-01

    Vertical transport associated with cumulus clouds is important to the redistribution of gases, particles, and energy, with subsequent consequences for many aspects of the climate system. Previous studies have suggested that detrainment from clouds can be comparable to the updraft mass flux, and thus represents an important contribution to vertical transport. In this study, we describe a new method to deduce the amounts of gross detrainment and entrainment experienced by non-precipitating cumulus clouds using aircraft observations. The method utilizes equations for three conserved variables: cloud mass, total water, and moist static energy. Optimizing these three equations leads to estimates of the mass fractions of adiabatic mixed-layer air, entrained air and detrained air that the sampled cloud has experienced. The method is applied to six flights of the CIRPAS Twin Otter during the Gulf of Mexico Atmospheric Composition and Climate Study (GoMACCS) which took place in the Houston, Texas region during the summer of 2006 during which 176 small, non-precipitating cumuli were sampled. Using our novel method, we find that, on average, these clouds were comprised of 30 to 70 % mixed-layer air, with entrained air comprising most of the remainder. The mass fraction of detrained air was usually very small, less than 2 %, although values larger than 10 % were found in 15 % of clouds. Entrained and detrained air mass fractions both increased with altitude, consistent with some previous observational studies. The largest detrainment events were almost all associated with air that was at their level of neutral buoyancy, which has been hypothesized in previous modeling studies. This new method could be readily used with data from other previous aircraft campaigns to expand our understanding of detrainment for a variety of cloud systems.

  14. Removal of PCDDs/Fs from municipal solid waste incineration by entrained-flow adsorption technology

    Institute of Scientific and Technical Information of China (English)

    YAN Jian-hua; PENG Zheng; LU Sheng-yong; LI Xiao-dong; CEN Ke-fa

    2006-01-01

    Entrained flow adsorption using activated carbon as the adsorbent is widely adopted for PCDDs/Fs-abatement in municipal solidwaste incineration (MSWI) process. The effects of operating parameters including flue gas temperature, feeding rate of activated carbon, polychlorinated dibenzodioxins and polychlorinated dibenzofurans (PCDDs/Fs) concentration at the inlet of the air pollution control device (APCD), filter materials, pressure drop on PCDDs/Fs removal efficiency are reviewed and commented upon in this paper. Evaluation on the various mechanistic models for entrained flow adsorption is carried out based on the computational simulation in terms of the actual operating condition and theoretical analysis. Finally, an advancement of entrained flow adsorption in combination of dual bag filter is introduced.

  15. Droplet impact on a liquid pool and bubble entrainment for low Bond numbers

    Science.gov (United States)

    Sleutel, Pascal; Tsai, Pei Hsun; Bouwhuis, Wilco; Thoraval, Marie-Jean; Visser, Claas-Willem; Wang, An-Bang; Versluis, Michel; Lohse, Detlef

    2015-11-01

    Droplets impacting on a pool of liquid and the subsequent bubble entrainment has been well studied for high Bond numbers where the droplets size is large and velocities are low. Here we study for the first time the droplet impact and bubble entrainment in an entirely new parameter regime (Bo ~ 10-2 -10-3 , U ~ 6-20 m/s, D ~ 0.08-0.4 mm). We follow up on the pioneering work of Oguz & Prosperetti, now in the surface tension dominated regime. We predict the bubble entrainment zone by balancing movement of the cavity bottom and droplet inertia with capillary waves enclosing the bubble. Both high-speed imaging experiments and numerical simulations in Gerris validate the model and show the importance of air for smaller droplet sizes.

  16. Gas entrainment inception at the border of a flow-swollen liquid surface

    International Nuclear Information System (INIS)

    A rapid liquid flow into a tank may impinge on the free surface, making it swell partially. The returning flow branches off from the free surface and re-submerges at the border of the swollen surface. If the flow velocity along the swollen surface is high enough, gas bubbles are formed at the border and entrained by the liquid flow. The conditions necessary for gas entrainment in a simple system are examined experimentally, using water and air as working fluids. The effect of surface tension is examined by adding a surface active agent to the water. The results show that gas entrainment inception is determined by the flow pattern in the system and the product of the Froude and Weber numbers based on the local velocity at the bubble formation point. (orig.)

  17. Inclined gravity currents filling basins: The influence of Reynolds number on entrainment into gravity currents

    Science.gov (United States)

    Hogg, Charlie A. R.; Dalziel, Stuart B.; Huppert, Herbert E.; Imberger, Jörg

    2015-09-01

    In many important natural and industrial systems, gravity currents of dense fluid feed basins. Examples include lakes fed by dense rivers and auditoria supplied with cooled air by ventilation systems. As we will show, the entrainment into such buoyancy driven currents can be influenced by viscous forces. Little work, however, has examined this viscous influence and how entrainment varies with the Reynolds number, Re. Using the idea of an entrainment coefficient, E, we derive a mathematical expression for the rise of the front at the top of the dense fluid ponding in a basin, where the horizontal cross-sectional area of the basin varies linearly with depth. We compare this expression to experiments on gravity currents with source Reynolds numbers, Res, covering the broad range 100 < Res < 1500. The form of the observed frontal rises was well approximated by our theory. By fitting the observed frontal rises to the theoretical form with E as the free parameter, we find a linear trend for E(Res) over the range 350 < Res < 1100, which is in the transition to turbulent flow. In the experiments, the entrainment coefficient, E, varied from 4 × 10-5 to 7 × 10-2. These observations show that viscous damping can be a dominant influence on gravity current entrainment in the laboratory and in geophysical flows in this transitional regime.

  18. Relationships of Entrainment Rate with Dynamical and Thermodynamic Properties in Shallow Convection

    Science.gov (United States)

    Lu, C.; Liu, Y.; Zhang, G. J.; Wu, X.; Endo, S.; Cao, L.; Li, Y.; Guo, X.

    2015-12-01

    This work examines the relationships of entrainment rate to vertical velocity, buoyancy, turbulent dissipation rate by applying stepwise principal component regression to observational data from shallow cumulus clouds collected during the Routine AAF [Atmospheric Radiation Measurement (ARM) Aerial Facility] Clouds with Low Optical Water Depths (CLOWD) Optical Radiative Observations (RACORO) field campaign over the ARM Southern Great Plains (SGP) site near Lamont, Oklahoma. The cumulus clouds during the RACORO campaign simulated using a large eddy simulation (LES) model are also examined with the same approach. The analysis shows that combination of multiple variables can better represent entrainment rate in both the observations and LES than the single-variable fitting equations and the three commonly used parameterizations. A new parameterization is thus presented that relates entrainment rate to vertical velocity, buoyancy and dissipation rate; the effects of treating clouds as ensembles and humid shells surrounding cumulus clouds on the new parameterization are discussed. Physical mechanisms underlying the relationships of entrainment rate to vertical velocity, buoyancy and dissipation rate are also explored. Furthermore, the effects of relative humidity in the entrained dry air on the above relationships are discussed; a possible physical mechanism for the effects is explored.

  19. Washing of the AW-101 entrained solids

    Energy Technology Data Exchange (ETDEWEB)

    GJ Lumetta

    2000-03-31

    BNFL Inc. (BNFL) is under contract with the US Department of Energy, River Protection Project (DOE-RPP) to design, construct, and operate facilities for treating wastes stored in the single-shell and double-shell tanks at the Hanford Site, Richland, Washington. The DOE-BNFL RPP contract identifies two feeds to the waste treatment plant: (1) primarily liquid low-activity waste (LAW) consisting of less than 2 wt% entrained solids and (2) high-level waste (HLW) consisting of 10 to 200 g/L solids slurry. This report describes the results of a test conducted by Battelle to assess the effects of inhibited water washing on the composition of the entrained solids in the diluted AW-101 low-activity waste (LAW) sample. The objective of this work was to gather data on the solubility of the AW-101 entrained solids in 0.01 M NaOH, so that BNFL can evaluate whether these solids require caustic leaching. The work was conducted according to test plan BNFL-TP-29953-9, Rev. 0, LAW Entrained Solids Water Wash and Caustic Leach Testing. The test went according to plan, with no deviations from the test plan. Based on the results of the 0.01 M NaOH washing, a decision was made by BNFL to not proceed with the caustic leaching test. The composition of the washed solids was such that caustic leaching would not result in significant reduction in the immobilized HLW volume.

  20. Washing of the AW-101 entrained solids

    International Nuclear Information System (INIS)

    BNFL Inc. (BNFL) is under contract with the US Department of Energy, River Protection Project (DOE-RPP) to design, construct, and operate facilities for treating wastes stored in the single-shell and double-shell tanks at the Hanford Site, Richland, Washington. The DOE-BNFL RPP contract identifies two feeds to the waste treatment plant: (1) primarily liquid low-activity waste (LAW) consisting of less than 2 wt% entrained solids and (2) high-level waste (HLW) consisting of 10 to 200 g/L solids slurry. This report describes the results of a test conducted by Battelle to assess the effects of inhibited water washing on the composition of the entrained solids in the diluted AW-101 low-activity waste (LAW) sample. The objective of this work was to gather data on the solubility of the AW-101 entrained solids in 0.01 M NaOH, so that BNFL can evaluate whether these solids require caustic leaching. The work was conducted according to test plan BNFL-TP-29953-9, Rev. 0, LAW Entrained Solids Water Wash and Caustic Leach Testing. The test went according to plan, with no deviations from the test plan. Based on the results of the 0.01 M NaOH washing, a decision was made by BNFL to not proceed with the caustic leaching test. The composition of the washed solids was such that caustic leaching would not result in significant reduction in the immobilized HLW volume

  1. Drugs of Abuse Can Entrain Circadian Rhythms

    Directory of Open Access Journals (Sweden)

    Ann E. K. Kosobud

    2007-01-01

    Full Text Available Circadian rhythms prepare organisms for predictable events during the Earth's 24-h day. These rhythms are entrained by a variety of stimuli. Light is the most ubiquitous and best known zeitgeber, but a number of others have been identified, including food, social cues, locomotor activity, and, most recently drugs of abuse. Given the diversity of zeitgebers, it is probably not surprising that genes capable of clock functions are located throughout almost all organs and tissues. Recent evidence suggests that drugs of abuse can directly entrain some circadian rhythms. We have report here that entrainment by drugs of abuse is independent of the suprachiasmatic nucleus and the light/dark cycle, is not dependent on direct locomotor stimulation, and is shared by a variety of classes of drugs of abuse. We suggest that drug-entrained rhythms reflect variations in underlying neurophysiological states. This could be the basis for known daily variations in drug metabolism, tolerance, and sensitivity to drug reward. These rhythms could also take the form of daily periods of increased motivation to seek and take drugs, and thus contribute to abuse, addiction and relapse.

  2. Liquid Droplet Detachment and Entrainment in Microscale Flows

    Science.gov (United States)

    Hidrovo, Carlos

    2005-11-01

    In this talk we will present a first order study of liquid water detachment and entrainment into air flows in hydrophobic microchannels. Silicon based microstructures consisting of 23 mm long U-shaped channels of different geometry were used for this purpose. The structures are treated with a Molecular Vapor Deposition (MVD) process that renders them hydrophobic. Liquid water is injected through a side slot located 2/3 of the way downstream from the air channel inlet. The water entering the air channel beads up into slugs or droplets that grow in size at this injection location until they fill and flood the channel or are carried away by the air flow. The slugs/droplets dimensions at detachment are correlated against superficial gas velocity and proper dimensionless parameters are postulated and examined to compare hydrodynamic forces against surface tension. It is found that slug/droplet detachment is dominated by two main forces: pressure gradient drag, arising from confinement of a viscous flow in the channel, and inertial drag, arising from the stagnation of the air due to obstruction by the slugs/droplets. A detachment regime map is postulated based on the relative importance of these forces under different flow conditions.

  3. Quality inspection system of cement-based materials supporting performance confirmation for radioactive waste repository. Part 1. Nondestructive evaluation of rebound number and air permeability of surface concrete of in-situ structures and laboratory specimens

    International Nuclear Information System (INIS)

    Applicability of nondestructive tests for quality inspection of cement-based materials in radioactive waste repository was researched experimentally in situ and laboratory. Two nondestructive tests for evaluation of the strength property and the mass transfer resistance of surface concrete, rebound hummer test and Torrent permeability test respectively were focused and discussed in terms of usability and future task. The results obtained by experiments on actual structures in situ show that rebound number measured by rebound hummer test is not always equivalent to air permeability of surface concrete measured by Torrent permeability test. This indicates the importance of nondestructive test related to mass transfer resistance for the sub-surface disposal of low-level radioactive waste requiring high-level nuclide-diffusion resistance is required. On the other hand, the results of laboratory test show several tasks on nondestructive evaluation of mass transfer resistance, for example the reexamining of correction method of Torrent air permeability based on moisture state in surface concrete. (author)

  4. Parameterizing Convective Organization to Escape the Entrainment Dilemma

    Science.gov (United States)

    Mapes, Brian; Neale, Richard

    2011-06-01

    Lateral mixing parameters in buoyancy-driven deep convection schemes are among the most sensitive and important unknowns in atmosphere models. Unfortunately, there is not a true optimum value for plume mixing rate, but rather a dilemma or tradeoff: Excessive dilution of updrafts leads to unstable stratification bias in the mean state, while inadequate dilution allows deep convection to occur too easily, causing poor space and time distributions and variability. In this too-small parameter space, compromises are made based on competing metrics of model performance. We attempt to escape this “entrainment dilemma” by making bulk plume parameters (chiefly entrainment rate) depend on a new prognostic variable (“organization,” org) meant to reflect the rectified effects of subgrid-scale structure in meteorological fields. We test an org scheme in the Community Atmosphere Model (CAM5) with a new unified shallow-deep convection scheme (UW-ens, a 2-plume version of the University of Washington scheme). Since buoyant ascent involves natural selection, subgrid structure makes convection systematically deeper and stronger than the pure unorganized case: plumes of average (or randomly sampled) air rising in the average environment. To reflect this, org is nonnegative, but we leave it dimensionless. A time scale characterizes its behavior (here ˜3 h for a 2o model). Currently its source is rain evaporation, but other sources can be added easily. We also let org be horizontally transported by advection, as a mass-weighted mean over the convecting layer. Linear coefficients link org to a plume ensemble, which it assists via: 1) plume base warmth above the mean temperature 2) plume radius enhancement (reduced mixing), and 3) increased probability of overlap in a multi-plume scheme, where interactions benefit later generations (this part has only been implemented in an offline toy column model). Since rain evaporation is a source for org, it functions as a time-lagged but

  5. Towards Better Understanding of Concrete Containing Recycled Concrete Aggregate

    Directory of Open Access Journals (Sweden)

    Hisham Qasrawi

    2013-01-01

    Full Text Available The effect of using recycled concrete aggregates (RCA on the basic properties of normal concrete is studied. First, recycled aggregate properties have been determined and compared to those of normal aggregates. Except for absorption, there was not a significant difference between the two. Later, recycled aggregates were introduced in concrete mixes. In these mixes, natural coarse aggregate was partly or totally replaced by recycled aggregates. Results show that the use of recycled aggregates has an adverse effect on the workability and air content of fresh concrete. Depending on the water/cement ratio and on the percent of the normal aggregate replaced by RCA, the concrete strength is reduced by 5% to 25%, while the tensile strength is reduced by 4% to 14%. All results are compared with previous research. As new in this research, the paper introduces a simple formula for the prediction of the modulus of elasticity of RCA concrete. Furthermore, the paper shows the variation of the air content of RAC.

  6. Designing Concrete Of New Era:“Self Compacting Concrete

    Directory of Open Access Journals (Sweden)

    Dharmesh K. Bhagat

    2014-02-01

    Full Text Available In India, infrastructure is given prior importance and it is vision to make India fully developed up till 2020.But, it is a challenging job to produce high strength concrete and one of the problems for this is presence of air voids. At present to reduce these voids many compacting machines like vibrators are used in field. But, this leads to high noise pollution and annoyance the person working on site. Thus, to eliminate this problem related to compaction, strength and noise, a new concrete called Self Compacting Concrete [SCC] is used. It reduces the voids as it flows under its own weight. The strength and durability of SCC is much higher compared to conventional concrete. It also helps in achieving high quality of surface finishes and becomes sustainable as it saves the energy. But, the problem with this type of concrete is that there is no specific mix design for it. Thus, the aim of this research is to give proper methodology for the mix design of self compacting concrete and various points to be kept in mind while designing such flowable concrete.

  7. Historic Concrete: From Concrete Repair to Concrete Conservation

    NARCIS (Netherlands)

    Heinemann, H.A.

    2013-01-01

    Concrete like materials were already applied during the Roman Empire. After the decline of the Roman Empire, a wide scale application of concrete only reappeared in the 19th century. Here lies also the origin of modern (reinforced) concrete. Since then, both concrete application and composition have

  8. Microphysical imprint of entrainment in warm cumulus

    OpenAIRE

    2013-01-01

    We analyse the cloud microphysical response to entrainment mixing in warm cumulus clouds observed from the CIRPAS Twin Otter during the GoMACCS field campaign near Houston, Texas, in summer 2006. Cloud drop size distributions and cloud liquid water contents from the Artium Flight phase-Doppler interferometer in conjunction with meteorological observations are used to investigate the degree to which inhomogeneous versus homogeneous mixing is preferred as a function of height above ...

  9. Microphysical imprint of entrainment in warm cumulus

    OpenAIRE

    Small, Jennifer D.; Chuang, Patrick Y.; Jonsson, Haflidi H.

    2013-01-01

    We analyse the cloud microphysical response to entrainment mixing in warm cumulus clouds observed from the CIRPAS Twin Otter during the GoMACCS field campaign near Houston, Texas, in summer 2006. Cloud drop size distributions and cloud liquid water contents from the Artium Flight phase-Doppler interferometer in conjunction with meteorological observations are used to investigate the degree to which inhomogeneous versus homogeneous mixing is preferred as a function of height above cloud base, ...

  10. Rod Driven Frequency Entrainment and Resonance Phenomena

    Directory of Open Access Journals (Sweden)

    Christina Salchow

    2016-08-01

    Full Text Available A controversy exists on photic driving in the human visual cortex evoked by intermittent photic stimulation. Frequency entrainment and resonance phenomena are reported for frequencies higher than 12 Hz in some studies while missing in others. We hypothesized that this might be due to different experimental conditions, since both high and low intensity light stimulation were used. However, most studies do not report radiometric measurements, which makes it impossible to categorize the stimulation according to photopic, mesopic, and scotopic vision. Low intensity light stimulation might lead to scotopic vision, where rod perception dominates. In this study, we investigated photic driving for rod-dominated visual input under scotopic conditions. Twelve healthy volunteers were stimulated with low intensity light flashes at 20 stimulation frequencies, leading to rod activation only. The frequencies were multiples of the individual alpha frequency (α of each volunteer in the range from 0.40–2.30*α. 306-channel whole head magnetoencephalography recordings were analyzed in time, frequency, and spatiotemporal domains with the Topographic Matching Pursuit algorithm. We found resonance phenomena and frequency entrainment for stimulations at or close to the individual alpha frequency (0.90–1.10*α and half of the alpha frequency (0.40–0.55*α. No signs of resonance and frequency entrainment phenomena were revealed around 2.00*α. Instead, on-responses at the beginning and off-responses at the end of each stimulation train were observed for the first time in a photic driving experiment at frequencies of 1.30–2.30*α, indicating that the flicker fusion threshold was reached. All results, the resonance and entrainment as well as the fusion effects, provide evidence for rod-dominated photic driving in the visual cortex.

  11. Rod Driven Frequency Entrainment and Resonance Phenomena

    Science.gov (United States)

    Salchow, Christina; Strohmeier, Daniel; Klee, Sascha; Jannek, Dunja; Schiecke, Karin; Witte, Herbert; Nehorai, Arye; Haueisen, Jens

    2016-01-01

    A controversy exists on photic driving in the human visual cortex evoked by intermittent photic stimulation. Frequency entrainment and resonance phenomena are reported for frequencies higher than 12 Hz in some studies while missing in others. We hypothesized that this might be due to different experimental conditions, since both high and low intensity light stimulation were used. However, most studies do not report radiometric measurements, which makes it impossible to categorize the stimulation according to photopic, mesopic, and scotopic vision. Low intensity light stimulation might lead to scotopic vision, where rod perception dominates. In this study, we investigated photic driving for rod-dominated visual input under scotopic conditions. Twelve healthy volunteers were stimulated with low intensity light flashes at 20 stimulation frequencies, leading to rod activation only. The frequencies were multiples of the individual alpha frequency (α) of each volunteer in the range from 0.40 to 2.30∗α. Three hundred and six-channel whole head magnetoencephalography recordings were analyzed in time, frequency, and spatiotemporal domains with the Topographic Matching Pursuit algorithm. We found resonance phenomena and frequency entrainment for stimulations at or close to the individual alpha frequency (0.90–1.10∗α) and half of the alpha frequency (0.40–0.55∗α). No signs of resonance and frequency entrainment phenomena were revealed around 2.00∗α. Instead, on-responses at the beginning and off-responses at the end of each stimulation train were observed for the first time in a photic driving experiment at frequencies of 1.30–2.30∗α, indicating that the flicker fusion threshold was reached. All results, the resonance and entrainment as well as the fusion effects, provide evidence for rod-dominated photic driving in the visual cortex. PMID:27588002

  12. Exploring Entrainment Patterns of Human Emotion in Social Media.

    Science.gov (United States)

    He, Saike; Zheng, Xiaolong; Zeng, Daniel; Luo, Chuan; Zhang, Zhu

    2016-01-01

    Emotion entrainment, which is generally defined as the synchronous convergence of human emotions, performs many important social functions. However, what the specific mechanisms of emotion entrainment are beyond in-person interactions, and how human emotions evolve under different entrainment patterns in large-scale social communities, are still unknown. In this paper, we aim to examine the massive emotion entrainment patterns and understand the underlying mechanisms in the context of social media. As modeling emotion dynamics on a large scale is often challenging, we elaborate a pragmatic framework to characterize and quantify the entrainment phenomenon. By applying this framework on the datasets from two large-scale social media platforms, we find that the emotions of online users entrain through social networks. We further uncover that online users often form their relations via dual entrainment, while maintain it through single entrainment. Remarkably, the emotions of online users are more convergent in nonreciprocal entrainment. Building on these findings, we develop an entrainment augmented model for emotion prediction. Experimental results suggest that entrainment patterns inform emotion proximity in dyads, and encoding their associations promotes emotion prediction. This work can further help us to understand the underlying dynamic process of large-scale online interactions and make more reasonable decisions regarding emergency situations, epidemic diseases, and political campaigns in cyberspace.

  13. Alignment strategies for the entrainment of music and movement rhythms.

    Science.gov (United States)

    Moens, Bart; Leman, Marc

    2015-03-01

    Theories of entrainment assume that spontaneous entrainment emerges from dynamic laws that operate via mediators on interactions, whereby entrainment is facilitated if certain conditions are fulfilled. In this study, we show that mediators can be built that affect the entrainment of human locomotion to music. More specifically, we built D-Jogger, a music player that functions as a mediator between music and locomotion rhythms. The D-Jogger makes it possible to manipulate the timing differences between salient moments of the rhythms (beats and footfalls) through the manipulation of the musical period and phase, which affect the condition in which entrainment functions. We conducted several experiments to explore different strategies for manipulating the entrainment of locomotion and music. The results of these experiments showed that spontaneous entrainment can be manipulated, thereby suggesting different strategies on how to embark. The findings furthermore suggest a distinction among different modalities of entrainment: finding the beat (the most difficult part of entrainment), keeping the beat (easier, as a temporal scheme has been established), and being in phase (no entrainment is needed because the music is always adapted to the human rhythm). This study points to a new avenue of research on entrainment and opens new perspectives for the neuroscience of music.

  14. Exploring Entrainment Patterns of Human Emotion in Social Media.

    Directory of Open Access Journals (Sweden)

    Saike He

    Full Text Available Emotion entrainment, which is generally defined as the synchronous convergence of human emotions, performs many important social functions. However, what the specific mechanisms of emotion entrainment are beyond in-person interactions, and how human emotions evolve under different entrainment patterns in large-scale social communities, are still unknown. In this paper, we aim to examine the massive emotion entrainment patterns and understand the underlying mechanisms in the context of social media. As modeling emotion dynamics on a large scale is often challenging, we elaborate a pragmatic framework to characterize and quantify the entrainment phenomenon. By applying this framework on the datasets from two large-scale social media platforms, we find that the emotions of online users entrain through social networks. We further uncover that online users often form their relations via dual entrainment, while maintain it through single entrainment. Remarkably, the emotions of online users are more convergent in nonreciprocal entrainment. Building on these findings, we develop an entrainment augmented model for emotion prediction. Experimental results suggest that entrainment patterns inform emotion proximity in dyads, and encoding their associations promotes emotion prediction. This work can further help us to understand the underlying dynamic process of large-scale online interactions and make more reasonable decisions regarding emergency situations, epidemic diseases, and political campaigns in cyberspace.

  15. Concrete Memories

    DEFF Research Database (Denmark)

    Wiegand, Frauke Katharina

    2015-01-01

    and poetic appropriations and inscriptions of the bunker site are depicted. Ranging between overlooked side presences and an overwhelming visibility, the concrete remains of fascist war architecture are involved in and motivate different sensuous experiences and mnemonic appropriations. The article meets...

  16. Diurnally entrained anticipatory behavior in archaea.

    Directory of Open Access Journals (Sweden)

    Kenia Whitehead

    Full Text Available By sensing changes in one or few environmental factors biological systems can anticipate future changes in multiple factors over a wide range of time scales (daily to seasonal. This anticipatory behavior is important to the fitness of diverse species, and in context of the diurnal cycle it is overall typical of eukaryotes and some photoautotrophic bacteria but is yet to be observed in archaea. Here, we report the first observation of light-dark (LD-entrained diurnal oscillatory transcription in up to 12% of all genes of a halophilic archaeon Halobacterium salinarum NRC-1. Significantly, the diurnally entrained transcription was observed under constant darkness after removal of the LD stimulus (free-running rhythms. The memory of diurnal entrainment was also associated with the synchronization of oxic and anoxic physiologies to the LD cycle. Our results suggest that under nutrient limited conditions halophilic archaea take advantage of the causal influence of sunlight (via temperature on O(2 diffusivity in a closed hypersaline environment to streamline their physiology and operate oxically during nighttime and anoxically during daytime.

  17. Progress in Lignin-based Concrete Admixtures%含木质素基混凝土外加剂的研究进展

    Institute of Scientific and Technical Information of China (English)

    谌凡琪

    2012-01-01

    综述了木质素在混凝土外加剂中的应用。工业木质素,尤其是木质素磺酸盐,可以充当混凝土减水剂、缓凝剂、引气剂和泵送剂。由于未经改性的工业木质素性能不够理想,为了提高木质素基混凝土添加剂的性能,宜对其进行适当的改性。碱木质素经过氧化、磺化、磺甲基化、接枝共聚等改性后,可以得到具有良好性能的混凝土外加剂。%The applications of lignin derivatives in concrete admixtures are reviewed. Technical lignins, especially lignosulfonates, can serve as concrete water reducers, retarders, air entraining agents and pumping agents. The performance of lignin is not good. Some appropriate modifications are sometimes required in order to improve the performance of the lignin-based concrete admixtures. Lignin-based concrete admixtures with good performaces can be obtained fxom alkali lignin after modifications such as oxidation, sulfonation, sulfomethylation and graft copolymerization.

  18. The influence of large-scale structures on entrainment in a decelerating transient turbulent jet revealed by large eddy simulation

    Science.gov (United States)

    Hu, Bing; Musculus, Mark P. B.; Oefelein, Joseph C.

    2012-04-01

    To provide a better understanding of the fluid mechanical mechanisms governing entrainment in decelerating jets, we performed a large eddy simulation (LES) of a transient air jet. The ensemble-averaged LES calculations agree well with the available measurements of centerline velocity, and they reveal a region of increased entrainment that grows as it propagates downstream during deceleration. Within the temporal and spatial domains of the simulation, entrainment during deceleration temporarily increases by roughly a factor of two over that of the quasi-steady jet, and thereafter decays to a level lower than the quasi-steady jet. The LES results also provide large-structure flow details that lend insight into the effects of deceleration on entrainment. The simulations show greater growth and separation of large vortical structures during deceleration. Ambient fluid is engulfed into the gaps between the large-scale structures, causing large-scale indentations in the scalar jet boundary. The changes in the growth and separation of large structures during deceleration are attributed to changes in the production and convection of vorticity. Both the absolute and normalized scalar dissipation rates decrease during deceleration, implying that changes in small-scale mixing during deceleration do not play an important role in the increased entrainment. Hence, the simulations predict that entrainment in combustion devices may be controlled by manipulating the fuel-jet boundary conditions, which affect structures at large scales much more than at small scales.

  19. Investigating porous concrete with improved strength: Testing at different scales

    NARCIS (Netherlands)

    Agar-Ozbek, A.S.; Weerheijm, J.; Schlangen, E.; Breugel, K. van

    2013-01-01

    Porous concrete incorporates a high percentage of meso-size air voids that makes its mechanical characteristics remarkably different from normal concrete. A research project was undertaken to design a special type of porous concrete, that fractures into small fragments when exposed to impact loading

  20. Use of SCC in Prefabricated Concrete Elements

    DEFF Research Database (Denmark)

    Thrane, Lars Nyholm; Lauritsen, Ib

    2004-01-01

    This paper presents observations made on the use of self-compacting concrete for pre-cast elements at Byggebjerg Beton A/S during the last 3 years. The elements include L- and sandwich elements and are mainly produced for agriculture purposes. In general, the flow properties and air content are...... concrete to achieve a good surface quality with a limited number of blowholes. For horizontal castings it is important to keep the concrete flowing to avoid casting joints. Blocking is avoided by using the right type of spacers and a maximum size aggregate of 8mm. However, if the concrete has to flow over...

  1. Experimental Analysis on Mix Proportion Design and Mechanical Properties of Anti-freezing and Anti-permeability Concrete with Low Strength%低强度抗冻抗渗混凝土配合比设计及力学特性试验分析

    Institute of Scientific and Technical Information of China (English)

    黄丽彬

    2015-01-01

    In this paper, the mix proportion of low strength concrete was designed by the scien-tific method, and its performance of anti-freezing and anti-permeability were studied, and the effect of the air entrainment agent dosage and the optimal water cement ratio on the anti-freezing performance, the anti-permeability performance and the strength of concrete were synchronously analyzed. Through deep research we can find out that in cold environment, the requirements of the anti-permeability performance and the strength of concrete should be meet in the construc-tion project, by using of low strength concrete, as long as adding moderate amount of air en-trained agent and maintaining appropriate water cement ratio, the persistent anti-freezing per-formance of the low strength concrete could be enhanced.%通过科学设计低强度混凝土的配合比,研究分析其抗冻、抗渗功能,并同步分析引气剂掺量、最优水灰比例对混凝土抗冻性、抗渗性及强度的作用。通过深入研究发现,严寒环境下符合建筑项目混凝土抗渗、强度的要求,采用低强度混凝土,只要掺入适量的引气剂、保持合适的水灰比例,就能增强低强度混凝土的持久的抗冻性能。

  2. Application of aggregate air-cooling system in concrete production of lock%骨料风冷系统在船闸混凝土生产中的应用

    Institute of Scientific and Technical Information of China (English)

    涂伟成; 丁碧珍; 蒋华东; 刘松

    2015-01-01

    在富春江船闸扩建改造工程风冷系统实际施工过程中,对粗骨料、拌合水、混凝土出机口温度以及浇筑温度进行实时监测,研究风冷骨料及制冷水系统的冷却能力,以指导后期施工。%According to the actual construction process of air cooling system of the Fuchun river lock expansion and improving project,through the real-time monitoring of coarse aggregate,mixing water,the concrete mixer outlet temperature and pouring temperature,this article gives a comprehensive study on the cooling capacity of the air-cooling aggregate and its cooling water system,to provide guidance for the later construction.

  3. Electrical pulses protect concrete

    OpenAIRE

    Van Kasteren, J.

    2006-01-01

    Even concrete is not as hard as it looks. Sea water, salt on icy roads, and indirectly even carbon dioxide from the air can corrode the steel of the reinforcing bars and so threaten the strength and integrity of a bridge pier, jetty, or viaduct. Dessi Koleva, a chemical engineer from Bulgaria, spent her doctoral research at the Faculty of Civil Engineering and Geosciences devising a method for the cathodic protection of steel rebars. The method is cheaper and also has fewer side effects on th...

  4. On the Correlation between Air Content and Air Bubble Parameters Frost Resistance Performance of High Fly Ash Content Concrete%关于大掺量粉煤灰混凝土含气量、气泡参数表征抗冻能力相关性的探讨

    Institute of Scientific and Technical Information of China (English)

    艾红梅; 戴碧琳; 郭建华; 杨晨光

    2015-01-01

    鉴于冻融作用对大掺量粉煤灰混凝土( High Fly ash Content Concrete,HFCC)造成的破坏较为严重,对国内外的研究情况进行了分析,总结了现阶段大掺量粉煤灰混凝土抗冻性能的研究进展。主要对混凝土拌合物含气量和硬化混凝土气泡参数表征HFCC抗冻性的科学性和可行性进行了分析,并且对二者的相关性进行探讨。%Given the freeze-thaw effect on high fly ash content concrete ( HFCC ) is relatively serious,the paper analyzes the domestic and foreign research and summarizes the present research progress of antifreeze performance of concrete with high volume of fly ash. This paper mainly analyzes the science and feasibility of concrete mixture air content and hardened concrete bubble parameters HFCC frost resistance and explores the correlation between the two.

  5. An experimental study of the liquid entrainment from swelled two-phase mixture surface in a reactor vessel

    International Nuclear Information System (INIS)

    An experimental study of liquid entrainment by rapid surface swellig of a two-phase mixture in a vessel has been performed. To investigate the effects of air flow and initial water level on the liquid entrainment, a series of experiments have been performed using air and water as working fluids. A total of 64 experimental liquid entrainment rate data have been obtained for various combinations of test parameters (i.e., six different initial water levels and varying air flow rates from 300 to 1,200 lpm) using two test vessels of the same height and different inner diameters (D=0.15 and 0.30m, respectively) for vertical bubbly and churn-turbulent flow conditions. An empirical correlation for the liquid entrainment rate, E, has been developed in terms of the superficial velocity of air, the initial water level, the density of gas, the surface tension, and the gravity. This correlation shows a good agreement with the present experimental data within 30% over a wide range of flow parameters

  6. 某大桥承台大体积混凝土温控分析%Temperature Control of Mass Concrete Construction of Fuping railway bridge

    Institute of Scientific and Technical Information of China (English)

    范倩倩

    2016-01-01

    某大桥26#墩承台施工,采用低热水泥,并掺入矿物、粉煤灰、引气剂和高效减水剂,降低水化热,增强混凝土强度、耐久性;分层浇筑、铺设冷循环水管,增强混凝土散热能力,降低混凝土内部温度;在施工过程严格实行控温保温养护措施,进行实时温度监测,实现了大体积混凝土温度控制的信息化施工,为混凝土保温保湿养护提供依据,为同类工程提供参考价值。%The mass concrete construction of number 26 pile cap of the Bridge makes use of low heat cement , mixed with mineral,fly ash,air-entraining agent,and concrete water-reducer to cut down the hydration heat as well as enhance the concrete strength and durability.Reducing the internal temperature of the concrete by set-ting circulating cooling water pipes and stratified pouring.The implementing of strict temperature control , preservation measures and real-time dynamic temperature monitoring in the working process makes the infor-mation construction of mass concrete temperature control come true.The study provides reference to the heat and humidity preservation of concrete and other similar projects.

  7. Air

    Science.gov (United States)

    ... house) Industrial emissions (like smoke and chemicals from factories) Household cleaners (spray cleaners, air fresheners) Car emissions (like carbon monoxide) *All of these things make up “particle pollution.” They mostly come from cars, trucks, buses, and ...

  8. 南水北调工程江苏境内泵站混凝土配合比试验%Research on concrete mix proportion for pump station construction within Jiangsu Province for South-North Water Diversion Project

    Institute of Scientific and Technical Information of China (English)

    陈建国; 胡智农

    2013-01-01

    探讨了粉煤灰、高效减水剂及引气剂掺量对混凝土性能的影响,为南水北调东线工程泵站混凝土提供施工配合比。通过掺入粉煤灰、高效减水剂及引气剂,配制了不同强度等级的混凝土,研究了C20、C25、C30等3种不同强度等级混凝土力学性能、耐久性能及体积稳定性,并用扫描电镜法(SEM)表征混凝土界面过渡区。研究表明:掺入粉煤灰、高效减水剂及引气剂后,混凝土立方体抗压强度均达到设计指标;在较高水胶比条件下,混凝土抗压、抗拉强度、弹性模量、抗渗性能均随着粉煤灰掺量增加而略有提高,同时掺入粉煤灰改善了混凝土界面过渡区。粉煤灰、高效减水剂及引气剂掺量分别不超过胶凝材料用量的30%、1%、0.015%时,所配制的C20、C25、C30混凝土满足南水北调工程江苏境内泵站混凝土施工要求。%The authors discuss the effects of different mixing amounts of fly ash,high rate water reducing agent and air-entraining agent on the properties of concrete. In order to study the concrete mix proportion for pump station construction of the east route of South-North Water Diversion Project,fly ash,water reducing agent and air-en-training agent were used to make concrete of C20,C30 and C30 with different strength. The mechanical properties, durability and stability of these three grades of concrete were studied,including characterization of concrete interfa-cial transition zone by scanning electron microscopy(SEM). The results of study show that compressive strength of concrete conforms to design specification after mixing of fly ash,high rate water reducing agent and air-entraining agent. At relatively high water-cement ratio,with increasing of fly ash content,the compressive strength,tensile strength,elastic modulus,impermeability of concrete increase slightly. Mixing of fly ash also improve the concrete interfacial transition zone. When the

  9. Conditions for super-adiabatic droplet growth after entrainment mixing

    Science.gov (United States)

    Yang, Fan; Shaw, Raymond; Xue, Huiwen

    2016-07-01

    Cloud droplet response to entrainment and mixing between a cloud and its environment is considered, accounting for subsequent droplet growth during adiabatic ascent following a mixing event. The vertical profile for liquid water mixing ratio after a mixing event is derived analytically, allowing the reduction to be predicted from the mixing fraction and from the temperature and humidity for both the cloud and environment. It is derived for the limit of homogeneous mixing. The expression leads to a critical height above the mixing level: at the critical height the cloud droplet radius is the same for both mixed and unmixed parcels, and the critical height is independent of the updraft velocity and mixing fraction. Cloud droplets in a mixed parcel are larger than in an unmixed parcel above the critical height, which we refer to as the "super-adiabatic" growth region. Analytical results are confirmed with a bin microphysics cloud model. Using the model, we explore the effects of updraft velocity, aerosol source in the environmental air, and polydisperse cloud droplets. Results show that the mixed parcel is more likely to reach the super-adiabatic growth region when the environmental air is humid and clean. It is also confirmed that the analytical predictions are matched by the volume-mean cloud droplet radius for polydisperse size distributions. The findings have implications for the origin of large cloud droplets that may contribute to onset of collision-coalescence in warm clouds.

  10. Stochastic entrainment of a stochastic oscillator.

    Science.gov (United States)

    Wang, Guanyu; Peskin, Charles S

    2015-01-01

    In this work, we consider a stochastic oscillator described by a discrete-state continuous-time Markov chain, in which the states are arranged in a circle, and there is a constant probability per unit time of jumping from one state to the next in a specified direction around the circle. At each of a sequence of equally spaced times, the oscillator has a specified probability of being reset to a particular state. The focus of this work is the entrainment of the oscillator by this periodic but stochastic stimulus. We consider a distinguished limit, in which (i) the number of states of the oscillator approaches infinity, as does the probability per unit time of jumping from one state to the next, so that the natural mean period of the oscillator remains constant, (ii) the resetting probability approaches zero, and (iii) the period of the resetting signal approaches a multiple, by a ratio of small integers, of the natural mean period of the oscillator. In this distinguished limit, we use analytic and numerical methods to study the extent to which entrainment occurs.

  11. Void structure of concrete with superabsorbent polymers and its relation to frost resistance of concrete

    DEFF Research Database (Denmark)

    Hasholt, Marianne Tange; Jensen, Ole Mejlhede; Laustsen, Sara

    2013-01-01

    the difference between poor and satisfactory frost-resistance. Furthermore, the results indicate that voids created directly by SAP protect concrete against frost deterioration just like other air voids; if the concrete contains enough SAP voids, these alone can provide sufficient frost resistance. © 2013 RILEM....

  12. Concrete evidence

    Energy Technology Data Exchange (ETDEWEB)

    Provis, J.; Duxson, P.; van Deventer, J. [University of Melbourne, Vic. (Australia)

    2008-11-15

    The time is right for a revolution in the cement industry which is responsible for 5-8% of all human-derived carbon dioxide emissions. Zeobond, an Australian company, has developed E-Crete which is a geopolymer concrete using fly ash and blast furnace slags which reduces CO{sub 2} emissions by 80% from the 0.67t of CO{sub 2} per ton of cement emitted by the Australian triple blend of cement, fly ash and slag. The article discusses the products development, standards for cements and challenges to the commercialization of E-Crete. 5 refs., 3 figs.

  13. Concrete construction engineering handbook

    CERN Document Server

    Nawy, Edward G

    2008-01-01

    Provides coverage of concrete construction engineering and technology. This work features discussions focusing on: the advances in engineered concrete materials; reinforced concrete construction; specialized construction techniques; and, design recommendations for high performance.

  14. Air

    International Nuclear Information System (INIS)

    In recent years several regulations and standards for air quality and limits for air pollution were issued or are in preparation by the European Union, which have severe influence on the environmental monitoring and legislation in Austria. This chapter of the environmental control report of Austria gives an overview about the legal situation of air pollution control in the European Union and in specific the legal situation in Austria. It gives a comprehensive inventory of air pollution measurements for the whole area of Austria of total suspended particulates, ozone, volatile organic compounds, nitrogen oxides, sulfur dioxide, carbon monoxide, heavy metals, benzene, dioxin, polycyclic aromatic hydrocarbons and eutrophication. For each of these pollutants the measured emission values throughout Austria are given in tables and geographical charts, the environmental impact is discussed, statistical data and time series of the emission sources are given and legal regulations and measures for an effective environmental pollution control are discussed. In particular the impact of fossil-fuel power plants on the air pollution is analyzed. (a.n.)

  15. Complementary testing techniques applied to obtain the freeze-thaw resistance of concrete

    Directory of Open Access Journals (Sweden)

    Romero, H. L.

    2015-03-01

    Full Text Available Most of the standards that evaluate the resistance of concrete against freeze-thaw cycles (FTC are based on the loss of weight due to scaling. Such procedures are useful but do not provide information about the microstructural deterioration of the concrete. The test procedure needs to be stopped after several FTCs for weighing the loss of material by scaling. This paper proposes the use of mercury-intrusion-porosimetry and thermogravimetric analysis for assessing the microstructural damage of concrete during FTCs. Continuous strain measurement can be performed without stopping the FTCs. The combination of the above techniques with the freeze-thaw resistance standards provides better and more precise information about concrete damage. The proposed procedure is applied to an ordinary concrete, a concrete with silica fume addition and one with an air-entraining agent. The test results showed that the three techniques used are suitable and useful to be employed as complementary to the standards.Las normas para evaluar la resistencia del hormigón a los ciclos hielo-deshielo (CHD se basan habitualmente en la pérdida de peso por descascarillamiento. Son útiles, pero no proporcionan información sobre el deterioro microestructural del hormigón. Además, exigen detener el ensayo para pesar el material desprendido. Se propone el uso complementario de la porosimetría por intrusión de mercurio y el análisis termogravimétrico para evaluar el daño microestructural del hormigón durante los CHDs. La medida continua de las deformaciones puede hacerse sin detener los CHDs. La combinación de las técnicas enumeradas con las normas de ensayo proporciona información más completa sobre el daño del hormigón. El procedimiento propuesto se aplica a un hormigón convencional, a un hormigón con adición de humo de sílice y a otro con aireante. Los resultados de los ensayos mostraron que las tres técnicas usadas son útiles y adecuadas como complemento a

  16. "Air embolism during fontan operation"

    Directory of Open Access Journals (Sweden)

    Madan Mohan Maddali

    2014-01-01

    Full Text Available In patients with a right to left intracardiac shunt, air embolism results in an obligatory systemic embolization. Nonembolization of entrained air is described in a child with a single ventricle physiology who had earlier undergone bidirectional Glenn shunt construction and Damus-Kaye-Stansel anastomosis. The air entrainment was detected by intra-operative transesophageal echocardiography. The combined effect of a "diving bell" phenomenon and mild aortic valve regurgitation are suggested as the reasons for the confinement of air into the ventricle preventing catastrophic systemic embolization.

  17. Dilution of aircraft exhaust and entrainment rates for trajectory box models

    Energy Technology Data Exchange (ETDEWEB)

    Gerz, T. [Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V. (DLR), Oberpfaffenhofen (Germany). Inst. fuer Physik der Atmosphaere; Kaercher, B. [Muenchen Univ. (Germany). Lehrstuhl fuer Bioklimatologie und Immissionsforschung

    1997-12-31

    In order to match in-situ measured concentrations of NO and NO{sub 2} in the wake, dilution factors or entrainment rates have to be used which take into account that the largest fraction of the exhaust is captured by the wing tip vortices. This fraction defines the primary wake. Baroclinicity and turbulence detrains parts of it later into the secondary wake. Both wake regimes undergo different chemical and microphysical histories. The rates {omega} are determined at which ambient air becomes entrained into the primary and the secondary portion of the exhaust plume. Numerical simulations of the highly resolved wake is used of cruising aircraft under typical atmosphere conditions with and without ambient turbulence. The simulations are oriented on a case where exhaust and dynamical data behind an eastbound travelling B-747 aircraft have been collected in-situ over the North-Atlantic east of Ireland. (author) 7 refs.

  18. Entrainment rates at the tops of laboratory analogs of cumulus and stratocumulus clouds

    Science.gov (United States)

    Górska, Anna; Malinowski, Szymon P.; Fugal, Jacob

    2015-04-01

    We investigate entrainment at tops of laboratory analogs of convective clouds: cumulus and stratocumulus. Cloudy saturated moist air (T ~22 °C) containing droplets of diameters of ~3-10 μm, is introduced into a laboratory cloud chamber of dimensions of 1.0×1.0×1.8 through an opening in the bottom wall. Initialy cloudy air fills ~60 cm thick layer at the bottom. Mixing between the cloud and unsaturated air above (T ~22 °C, RH ~35 %) results in evaporative cooling triggering convection which, in turn, leads to formation of a well mixed layer capperd with a temperature inversion. The temperature jump is about 2 °C within ~30 cm deep layer. Then updrafts are forced through a 30cm high tube extending from the bottom of the chamber. "Strong' updrafts which penetrate the whole inversion layer mimic overshooting cumulus clouds while "weak' updrafts diverging under the inversion simulate stratocumulus clouds. We use a laser sheet technique to image two-dimensional cross sections through the clouds. A specially developed mutiscale Particle Image Velicimetry (PIV) algorithm allows to retrieve 2D velocity fields. Suitable image processing allows to determine cloud-clear air interface in the images. Extracting velocities of cloudy (ui) and environmental (ua) air on both sides of the interface allows us calculate entrainment / detrainment rates: E = -ρa(ua - ui) - entrainment rate D = ρa(ua - ui) - detrainment rate. On the poster we will present fine structures of entraimnet/dertaiment process and discuss similarities and differences in both investigated types of clouds.

  19. Synchronization and entrainment of coupled circadian oscillators

    CERN Document Server

    Komin, Niko; Hernandez-Garcia, Emilio; Toral, Raul

    2010-01-01

    Circadian rhythms in mammals are controlled by the neurons located in the suprachiasmatic nucleus of the hypothalamus. In physiological conditions, the system of neurons is very efficiently entrained by the 24-hour light-dark cycle. Most of the studies carried out so far emphasize the crucial role of the periodicity imposed by the light dark cycle in neuronal synchronization. Nevertheless, heterogeneity as a natural and permanent ingredient of these cellular interactions is seemingly to play a major role in these biochemical processes. In this paper we use a model that considers the neurons of the suprachiasmatic nucleus as chemically-coupled modified Goodwin oscillators, and introduce non-negligible heterogeneity in the periods of all neurons in the form of quenched noise. The system response to the light-dark cycle periodicity is studied as a function of the interneuronal coupling strength, external forcing amplitude and neuronal heterogeneity. Our results indicate that the right amount of heterogeneity hel...

  20. Concrete durability

    Directory of Open Access Journals (Sweden)

    Gaspar Tébar, Demetrio

    1991-03-01

    Full Text Available The evidence that the concrete is not a material for ever was noticed from the beginning of its industrial use. In the present work, the author describes the studies carried out during the last century and the early ages of the present one, mainly devoted to the study of the durability in sea water. At the present days, and in spite of the numerous papers published from then, the study of the concrete durability continues focusing the research priorities and economical resources of researchers and industries related with this material. Moreover, the new laboratory techniques are allowing to understand old problems and even to open again the discussion on reaction mechanisms which were believed to be completely understood. The article finalizes with a brief description of the numerous studies carried out at the Institute Eduardo Torroja on concrete durability, mainly those related with the resistance against gypsum attack (so abundant in our country land and against sea water attack.

    La realidad de que el hormigón no es un material eterno y es susceptible de sufrir ataques por agentes químicos, fue constatada desde el comienzo mismo de su uso industrial. En el presente trabajo el autor enumera los estudios realizados el siglo pasado y a comienzos del presente sobre la durabilidad del hormigón en agua de mar. En la actualidad y a pesar de los numerosos trabajos desarrollados desde entonces, el estudio de la durabilidad del hormigón sigue centrando la atención prioritaria y los recursos económicos de los investigadores e industrias relacionadas con este material. Además las nuevas técnicas de estudio están permitiendo comprender antiguos problemas e incluso reabrir la discusión sobre mecanismos de reacción que se creían completamente explicados. Finaliza el artículo con una descripción somera de los múltiples trabajos realizados en el Instituto Eduardo Torreja sobre la materia, en especial los estudios realizados sobre

  1. An Alternative Mechanism for Accelerated Carbon Sequestration in Concrete

    Energy Technology Data Exchange (ETDEWEB)

    Haselbach, Liv M.; Thomle, Jonathan N.

    2014-07-01

    The increased rate of carbon dioxide sequestration (carbonation) is desired in many primary and secondary life applications of concrete in order to make the life cycle of concrete structures more carbon neutral. Most carbonation rate studies have focused on concrete exposed to air under various conditions. An alternative mechanism for accelerated carbon sequestration in concrete was investigated in this research based on the pH change of waters in contact with pervious concrete which have been submerged in carbonate laden waters. The results indicate that the concrete exposed to high levels of carbonate species in water may carbonate faster than when exposed to ambient air, and that the rate is higher with higher concentrations. Validation of increased carbon dioxide sequestration was also performed via thermogravimetric analysis (TGA). It is theorized that the proposed alternative mechanism reduces a limiting rate effect of carbon dioxide dissolution in water in the micro pores of the concrete.

  2. Entrainment of neural oscillations as a modifiable substrate of attention.

    Science.gov (United States)

    Calderone, Daniel J; Lakatos, Peter; Butler, Pamela D; Castellanos, F Xavier

    2014-06-01

    Brain operation is profoundly rhythmic. Oscillations of neural excitability shape sensory, motor, and cognitive processes. Intrinsic oscillations also entrain to external rhythms, allowing the brain to optimize the processing of predictable events such as speech. Moreover, selective attention to a particular rhythm in a complex environment entails entrainment of neural oscillations to its temporal structure. Entrainment appears to form one of the core mechanisms of selective attention, which is likely to be relevant to certain psychiatric disorders. Deficient entrainment has been found in schizophrenia and dyslexia and mounting evidence also suggests that it may be abnormal in attention-deficit/hyperactivity disorder (ADHD). Accordingly, we suggest that studying entrainment in selective-attention paradigms is likely to reveal mechanisms underlying deficits across multiple disorders.

  3. 含盐环境中混凝土的破坏研究%Deterioration of Concrete Exposed to Salt Environment

    Institute of Scientific and Technical Information of China (English)

    季辉; 杨全兵

    2011-01-01

    The effect of salt crystallization of Na2SO4 and NaCl on scaling deterioration, expansion rate of salt crystallization and strength of concrete exposed to dry-wet cycles were investigated, and compared with the chemical attack of concrete soaked in Na2SO4 and NaCl solutions at normal temperature. The result shows that (1) the salt-crystallized deterioration of concrete exposed to dry-wet cycles was more severe than the chemical attack; (2) the deterioration of concrete due to salt crystallization caused by Na2SO4 was more severe than that caused by NaCl; ( 3 ) the scaling and expansion of concrete due to salt crystallization obviously increased with the increase of salt concentration and the number of drying-wetting cycles, and the concrete after drying did not shrink but expanded when the number of drying-wetting cycles exceeded a certain value; (4) the salt crystals have some densified and strengthened effects on the concrete at first, and the expansion and deterioration of the concrete occurred only when the amount of salt crystals exceeded a certain value; (5) the salt-crystallized deterioration of concrete was significantly mitigated by air-entraining.%研究了在干湿循环作用下,Na2SO4和NaCl盐结晶对混凝土盐剥蚀破坏、盐结晶膨胀率和强度的影响,并与常温浸泡下的化学侵蚀进行对比分析.结果表明,混凝土在干湿循环作用下的盐结晶破坏明显比化学侵蚀破坏更严重;Na2SO4产生的盐结晶破坏明显高于NaCl;盐结晶产生的混凝土膨胀和剥蚀破坏随着盐浓度和干湿循环次数的增加明显增大,且超过一定循环次数后,混凝土经干燥后,非但不收缩,反而继续膨胀;盐晶体刚开始主要起到密实与增强的作用,只有盐结晶量超过一定值后,才会引起混凝土膨胀和破坏;引气可以显著降低和延缓混凝土的盐结晶破坏.

  4. 空冷凝汽器支架结构管柱抗震性能研究%STUDY ON SEISMIC BEHAVIOR OF TUBULAR REINFORCED CONCRETE COLUMNS OF AIR-COOLED SUPPORT STRUCTURE

    Institute of Scientific and Technical Information of China (English)

    杜宁军

    2013-01-01

    对应用于空间钢桁架空冷凝汽器支架结构的大尺寸、小壁径比钢筋混凝土管柱的抗震性能进行了试验及数值模拟.制作了四个缩尺比为1/8的钢筋混凝土管柱试件,并进行了拟静力试验,得出了各试件的滞回曲线、骨架曲线等.利用OpenSecs对钢筋混凝土管柱进行了低周反复加载条件下的非线性分析.结果显示,计算所得的滞回曲线、骨架曲线与试验所得的曲线大体吻合,这表明通过OpenSees所建立的空心管柱有限元模型能够比较好地模拟这种大尺寸、小壁径比钢筋混凝土管柱的受力以及耗能性能.%The seismic behavior of great-size thin-wall tubular reinforced concrete columns used by air-cooled condenser support system is experimentally and numerically investigated.Fistly,four specimens 1/8 of prototype reinforced concrete columns are fabricated.Then,they are tested under repeated horizontal load with constant axial loads.Finally,the nonlinear finite element models are established to simulate the seismic behavior of great-size thin-wall tubular reinforced concrete under low-cycle and reverse horizontal loading test by using OpenSees.The results show that the hysteretic curves and skeleton curves match well with the experimental curves,so the nonlinear finite element model could accurately simulate the seismic behavior of tubular reinforced concrete columns.

  5. Electrical Resistance Tomography imaging of concrete

    KAUST Repository

    Karhunen, Kimmo

    2010-01-01

    We apply Electrical Resistance Tomography (ERT) for three dimensional imaging of concrete. In ERT, alternating currents are injected into the target using an array of electrodes attached to the target surface, and the resulting voltages are measured using the same electrodes. These boundary measurements are used for reconstructing the internal (3D) conductivity distribution of the target. In reinforced concrete, the metallic phases (reinforcing bars and fibers), cracks and air voids, moisture gradients, and the chloride distribution in the matrix carry contrast with respect to conductivity. While electrical measurements have been widely used to characterize the properties of concrete, only preliminary results of applying ERT to concrete imaging have been published so far. The aim of this paper is to carry out a feasibility evaluation with specifically cast samples. The results indicate that ERT may be a feasible modality for non-destructive evaluation of concrete. © 2009 Elsevier Ltd. All rights reserved.

  6. High-temperature entrained flow gasification of biomass

    DEFF Research Database (Denmark)

    Qin, Ke; Lin, Weigang; Jensen, Peter Arendt;

    2012-01-01

    Biomass (wood and straw) gasification has been studied in a laboratory scale atmospheric pressure entrained flow reactor. Effects of reaction temperature, steam/carbon molar ratio, excess air ratio, and biomass type on the solid, liquid and gas products were investigated. The biomass was completely...... converted at all investigated operating conditions and the syngas contained nearly no tar but some soot at the highest applied reaction temperature of 1350°C. With a rise of reaction temperature from 1000°C to 1350°C, the yield of producer gas (defined as the sum of H2, CO, CO2 and hydrocarbons up to C3...... species) increased dramatically by 72%. The H2/CO molar ratio in syngas was close to 1 at reaction temperature above 1200°C with steam addition. Higher temperature was beneficial to lower the amount of tar while the soot yield showed a peak of 56.7g/kg fuel at 1200°C. With steam addition, the producer gas...

  7. Designing Concrete Of New Era:“Self Compacting Concrete

    OpenAIRE

    Dharmesh K. Bhagat; Nandan H. Dawda

    2014-01-01

    In India, infrastructure is given prior importance and it is vision to make India fully developed up till 2020.But, it is a challenging job to produce high strength concrete and one of the problems for this is presence of air voids. At present to reduce these voids many compacting machines like vibrators are used in field. But, this leads to high noise pollution and annoyance the person working on site. Thus, to eliminate this problem related to compaction, strength and noise,...

  8. Biomass Gasification Behavior in an Entrained Flow Reactor: Gas Product Distribution and Soot Formation

    DEFF Research Database (Denmark)

    Qin, Ke; Jensen, Peter Arendt; Lin, Weigang;

    2012-01-01

    . In comparison to pyrolysis, lower yields of soot, H2, and CO were produced during gasification. The yield of soot could be reduced by a longer residence time, larger feeder air flow, lower oxygen concentration, higher excess air ratio, higher steam/carbon ratio, and higher reactor temperature. Changes...... in residence time, feeder air flow, and oxygen concentration did not show a noticeable influence on H2 and CO yields. Increasing the excess air ratio decreased both the H2 and CO yields; increasing the steam/carbon ratio increased the H2 yield but decreased the CO yield; and increasing the reactor temperature......Biomass gasification and pyrolysis were studied in a laboratory-scale atmospheric pressure entrained flow reactor. Effects of operating parameters and biomass types on the syngas composition were investigated. In general, the carbon conversion during biomass gasification was higher than 90...

  9. Self-Compacting Concrete

    OpenAIRE

    Okamura, Hajime; OUCHI, Masahiro

    2003-01-01

    Self-compacting concrete was first developed in 1988 to achieve durable concrete structures. Since then, various investigations have been carried out and this type of concrete has been used in practical structures in Japan, mainly by large construction companies. Investigations for establishing a rational mix-design method and self-compactability testing methods have been carried out from the viewpoint of making self-compacting concrete a standard concrete.

  10. A real-scale field experiment of debris flow for investigating its deposition and entrainment

    Science.gov (United States)

    Paik, J.; Son, S.; Kim, T.; Kim, S.

    2012-12-01

    In mountain area debris flows typically mobilize from slides and entrain channel materials as they propagate down over the surface of hill slope and valley. Consequently, cross-sectional averaged discharge of debris flows may increases due to the entrainment of channel materials over steep slopes while decrease due to deposition of large material at mile slopes. In this work, the erosional and depositional patterns of debris flow have been investigated through a real-scale field experiment in a mountain basin in Gangwon, Korea. The experimental basin is about 800 m long and the channel width ranges between 8 m and 25 m. The angle of the channel slope varies from 38° near the upstream end to 5° at the downstream end where a check has been installed. In the experiment, 300 cubic meters of saturated solid-fluid mixture is suddenly released by opening a gate of a concrete reservoir installed at the upstream of the basin, along with additional 10.0 cubic meters of water per second for 30 seconds. We employ several sensors for measuring the speed, depth variation and total normal and fluid pore pressures at the channel bed as the debris flow propagates downslope. The velocity and depth of the debris flow are measured using ultrasonic sensors with a measuring range up to 10 m and video recording systems. A load cell and eight pore pressure transducers ranging up 30 psia are used to measure the total normal and pore-water pressures at the base of the debris flow. Through a quantitative analysis of these experimental measurements and high-resolution LiDAR topographic data we investigate the deposition and entrainment features of debris flow. We introduce the details of the full-scale experimental basin, facility, sensors and procedure, and provide some our experimental observations.

  11. Self-cleaning geopolymer concrete - A review

    Science.gov (United States)

    Norsaffirah Zailan, Siti; Mahmed, Norsuria; Bakri Abdullah, Mohd Mustafa Al; Sandu, Andrei Victor

    2016-06-01

    Concrete is the most widely used construction materials for building technology. However, cement production releases high amounts of carbon dioxide (CO2) to the atmosphere that leads to increasing the global warming. Thus, an alternative, environmental friendly construction material such as geopolymer concrete has been developed. Geopolymer concrete applies greener alternative binder, which is an innovative construction material that replaces the Portland cement. This technology introduced nano-particles such as nanoclay into the cement paste in order to improve their mechanical properties. The concrete materials also have been developed to be functioned as self-cleaning construction materials. The self-cleaning properties of the concrete are induced by introducing the photocatalytic materials such as titania (TiO2) and zinc oxide (ZnO). Self-cleaning concrete that contains those photocatalysts will be energized by ultraviolet (UV) radiation and accelerates the decomposition of organic particulates. Thus, the cleanliness of the building surfaces can be maintained and the air surrounding air pollution can be reduced. This paper briefly reviews about self-cleaning concrete.

  12. Influence of Additives on Reinforced Concrete Durability

    Directory of Open Access Journals (Sweden)

    Neverkovica Darja

    2014-12-01

    Full Text Available The article presents the results of the research on carbonation and chloride induced corrosion mechanisms in reinforced concrete structures, based on three commercially available concrete admixtures: Xypex Admix C-1000, Penetron Admix and Elkem Microsilica. Carbonation takes place due to carbon dioxide diffusion, which in the required amount is present in the air. Chlorides penetrate concrete in case of the use of deicing salt or structure exploitation in marine atmosphere. Based on the implemented research, Elkem Microsilica is the recommended additive for the use in aggressive environmental conditions. Use of Xypex Admix C-1000 and Penetron Admix have only average resistance to the aggressive environmental impact.

  13. Numerical Investigation of Entrainment of Turbulent Dense Currents

    Science.gov (United States)

    Bhaganaagar, Kiran; Nayamatulla, Manjure

    2016-04-01

    Entrainment in dense overflows has fundamental importance for understanding the transport of densest water in the ocean. Estimation of entrainment is extremely challenging and to-date we do not have a fundamental framework that parameterizes entrainment. A highly accurate direct numerical simulation and large eddy simulation solvers have been developed to simulate dense currents over range of smooth- and rough-surfaces. Simulations have been performed for both lock-exchange currents and constant flux currents. A mathematical framework has been developed to estimate entrainment of 2-D and 3-D dense currents. Entrainment has been calculated from first-principles as the relative change in the volume of the dense current in time with respect to the buoyancy forcing that drives the dense current. A combination of threshold method, wherein the height of current is evaluated as height corresponding to the specified threshold value and sorting method, wherein, the mixed fluid is sorted into bins ranging from dense fluid at the bottom to ambient fluid at the top has been used to evaluate the interface between the dense and ambient fluid. Entrainment is sensitive to the method of evaluation of the interface height. Finally, we obtained the dependency of entrainment parameter on non-dimensional parameters. Analysis has demonstrated lock-exchange currents have less mixing and entrainment for same Reynolds number and Froude's number than constant flux currents. The differences exist due to differences in nature of Kelvin-Helmholtz instabilities and lobe-cleft currents. Rough-bottom surfaces introduces additional dynamics of the dense currents. The spacing between the roughness elements has demonstrated to be important metric in entrainment parameters for lock-exchange currents. Densely spaced (D-type) currents travel slower as roughness causes hindrance on density current propagation due to enhanced drag and produces additional eddies and instabilities compared to sparsely

  14. Reinforced plaster by means of the synergic action between concrete additives (superfluidifiers, fluidiflers and airing-plasticizers and E glass fibres

    Directory of Open Access Journals (Sweden)

    del Río Merino, M.

    2000-12-01

    Full Text Available Through the analysis of the different compounds (plaster + additives + E glass fibres we pretend to demostrate that a synergic action is present between certain concrete additives (superfluidifiers, fluidiflers, and airingplasticizers and E glass fibre, on the basis of the flection resistance of plaster matrix based compound materials.

    Mediante el análisis de diferentes compuestos (escayola + aditivos + fibras de vidrio E se pretende demostrar que existe una acción sinérgica entre ciertos aditivos del hormigón (superfluidificantes, fluidificantes y aireantes-plastificantes y los refuerzos a base de fibras de vidrio E, sobre la resistencia a flexión de los materiales compuestos de matriz principal escayola.

  15. Gas entrainment at free surface of liquid, 2

    International Nuclear Information System (INIS)

    The onset conditions of vortex-induced air entrainment were investigated for the suction flow into a vertical drawing pipe in a cylindrical test vessel. It was found that the onset conditions can be represented by the following two types of empirical criteria: Ron = a1.52(H/D)-1.52 for large Fr, Frn = c0.847(H/D)-0.84 for large Ro, (a = 1.9 x 10-4/D, c = 0.14/D), where D is the inner diameter of the suction pipe in the unit of meter, H the submergence, Fr the Froude number (= V12/gH), and Ro the rotational Froude number (= C∞2/gH3). The subscript n on Ro and Fr denotes the onset correlations derived independently from the relation between Ro and H/D and the relation between Fr and H/D. From visual observation and theoretical consideration, it was found that the above two criteria come from the fact that the onset conditions are dominated by the following two factors: whether the air core formed by vortex reaches the pipe, and whether the water flow in the suction pipe is fast enough for the flow to draw bubbles downward. By combing the two onset criteria into single correlation and comparing it with experimental data, the following correlation was derived, log10(Fr/Frn)log10(Ro/Ron) = h, ( h = 5.71 x 10-4(H/D)1.54). It was confirmed that this correlation represents all the experimental data well. (author)

  16. Microcracking and durability of high strength concretes

    International Nuclear Information System (INIS)

    Durability of 28 days compressive strength concrete of 20 to 120 MPa has been studied. The ability of concrete to transport aggressive agents has been determined for four properties: the air permeability, the chloride diffusivity, the water absorption and the carbonation. A chloride migration test for high and very high strength concrete (HSC and VHSC) has been built. The relationship between transport properties and the compressive strength after one and 28 days of humid curing has always the same shape: transport decreases when strength increases. However, transport properties often vary in the ordinary concrete field. Beyond, the domain is much more limited. The relationship between transport properties and strength valid for ordinary concrete can not be simply extrapolated for HSC and VHSC. To determine the part of microcracking of HSC and VHSC, concrete behaviour stored in two mediums has been studied: the ones shaming the storing condition of concrete in auto-desiccation, the others reproducing the storing conditions of concrete in desiccation. Auto-desiccation (measuring relative humidity at balance) and desiccation (measuring mass losses) have been showed. Microcracks and shrinkage strains have been measured. It has been showed that auto-desiccation microcracks proving in HSC or VHSC don't question the durability. Microcracks, as for permeability, do not develop between 28 days and one year. On the contrary, desiccation microcracks observed in HSC and VHSC, increase with transport properties between 28 days and 1.5 year. Thus, a bulk concrete is always more durable than a cover concrete. At last, the good influence of increase of curing of 1 to 28 days on the transport of all concretes has been emphasized. (author)

  17. On the maximum grain size entrained by photoevaporative winds

    Science.gov (United States)

    Hutchison, Mark A.; Laibe, Guillaume; Maddison, Sarah T.

    2016-09-01

    We model the behaviour of dust grains entrained by photoevaporation-driven winds from protoplanetary discs assuming a non-rotating, plane-parallel disc. We obtain an analytic expression for the maximum entrainable grain size in extreme-UV radiation-driven winds, which we demonstrate to be proportional to the mass loss rate of the disc. When compared with our hydrodynamic simulations, the model reproduces almost all of the wind properties for the gas and dust. In typical turbulent discs, the entrained grain sizes in the wind are smaller than the theoretical maximum everywhere but the inner disc due to dust settling.

  18. On the maximum grain size entrained by photoevaporative winds

    CERN Document Server

    Hutchison, Mark A; Maddison, Sarah T

    2016-01-01

    We model the behaviour of dust grains entrained by photoevaporation-driven winds from protoplanetary discs assuming a non-rotating, plane-parallel disc. We obtain an analytic expression for the maximum entrainable grain size in extreme-UV radiation-driven winds, which we demonstrate to be proportional to the mass loss rate of the disc. When compared with our hydrodynamic simulations, the model reproduces almost all of the wind properties for the gas and dust. In typical turbulent discs, the entrained grain sizes in the wind are smaller than the theoretical maximum everywhere but the inner disc due to dust settling.

  19. Cellular lightweight concrete containing high-calcium fly ash and natural zeolite

    Science.gov (United States)

    Jitchaiyaphum, Khamphee; Sinsiri, Theerawat; Jaturapitakkul, Chai; Chindaprasirt, Prinya

    2013-05-01

    Cellular lightweight concrete (CLC) with the controlled density of approximately 800 kg/m3 was made from a preformed foam, Type-I Portland cement (OPC), fly ash (FA), or natural zeolite (NZ), and its compressive strength, setting time, water absorption, and microstructure of were tested. High-calcium FA and NZ with the median particle sizes of 14.52 and 7.72 μm, respectively, were used to partially replace OPC at 0, 10wt%, 20wt%, and 30wt% of the binder (OPC and pozzolan admixture). A water-to-binder mass ratio (W/B) of 0.5 was used for all mixes. The testing results indicated that CLC containing 10wt% NZ had the highest compressive strength. The replacement of OPC with NZ decreased the total porosity and air void size but increased the capillary porosity of the CLC. The incorporation of a suitable amount of NZ decreased the setting time, total porosity, and pore size of the paste compared with the findings with the same amount of FA. The total porosity and cumulative pore volume decreased, whereas the gel and capillary pores increased as a result of adding both pozzolans at all replacement levels. The water absorption increased as the capillary porosity increased; this effect depended on the volume of air entrained and the type or amount of pozzolan.

  20. Music and emotions: from enchantment to entrainment.

    Science.gov (United States)

    Vuilleumier, Patrik; Trost, Wiebke

    2015-03-01

    Producing and perceiving music engage a wide range of sensorimotor, cognitive, and emotional processes. Emotions are a central feature of the enjoyment of music, with a large variety of affective states consistently reported by people while listening to music. However, besides joy or sadness, music often elicits feelings of wonder, nostalgia, or tenderness, which do not correspond to emotion categories typically studied in neuroscience and whose neural substrates remain largely unknown. Here we review the similarities and differences in the neural substrates underlying these "complex" music-evoked emotions relative to other more "basic" emotional experiences. We suggest that these emotions emerge through a combination of activation in emotional and motivational brain systems (e.g., including reward pathways) that confer its valence to music, with activation in several other areas outside emotional systems, including motor, attention, or memory-related regions. We then discuss the neural substrates underlying the entrainment of cognitive and motor processes by music and their relation to affective experience. These effects have important implications for the potential therapeutic use of music in neurological or psychiatric diseases, particularly those associated with motor, attention, or affective disturbances.

  1. Music and emotions: from enchantment to entrainment.

    Science.gov (United States)

    Vuilleumier, Patrik; Trost, Wiebke

    2015-03-01

    Producing and perceiving music engage a wide range of sensorimotor, cognitive, and emotional processes. Emotions are a central feature of the enjoyment of music, with a large variety of affective states consistently reported by people while listening to music. However, besides joy or sadness, music often elicits feelings of wonder, nostalgia, or tenderness, which do not correspond to emotion categories typically studied in neuroscience and whose neural substrates remain largely unknown. Here we review the similarities and differences in the neural substrates underlying these "complex" music-evoked emotions relative to other more "basic" emotional experiences. We suggest that these emotions emerge through a combination of activation in emotional and motivational brain systems (e.g., including reward pathways) that confer its valence to music, with activation in several other areas outside emotional systems, including motor, attention, or memory-related regions. We then discuss the neural substrates underlying the entrainment of cognitive and motor processes by music and their relation to affective experience. These effects have important implications for the potential therapeutic use of music in neurological or psychiatric diseases, particularly those associated with motor, attention, or affective disturbances. PMID:25773637

  2. Organic Entrainment and Preservation in Volcanic Glasses

    Science.gov (United States)

    Wilhelm, Mary Beth; Ojha, Lujendra; Brunner, Anna E.; Dufek, Josef D.; Wray, James Joseph

    2014-01-01

    Unaltered pyroclastic deposits have previously been deemed to have "low" potential for the formation, concentration and preservation of organic material on the Martian surface. Yet volcanic glasses that have solidified very quickly after an eruption may be good candidates for containment and preservation of refractory organic material that existed in a biologic system pre-eruption due to their impermeability and ability to attenuate UV radiation. Analysis using NanoSIMS of volcanic glass could then be performed to both deduce carbon isotope ratios that indicate biologic origin and confirm entrainment during eruption. Terrestrial contamination is one of the biggest barriers to definitive Martian organic identification in soil and rock samples. While there is a greater potential to concentrate organics in sedimentary strata, volcanic glasses may better encapsulate and preserve organics over long time scales, and are widespread on Mars. If volcanic glass from many sites on Earth could be shown to contain biologically derived organics from the original environment, there could be significant implications for the search for biomarkers in ancient Martian environments.

  3. Granular motions near the threshold of entrainment

    Science.gov (United States)

    Valyrakis, Manousos; Alexakis, athanasios-Theodosios

    2016-04-01

    Our society is continuously impacted by significant weather events many times resulting in catastrophes that interrupt our normal way of life. In the context of climate change and increasing urbanisation these "extreme" hydrologic events are intensified both in magnitude and frequency, inducing costs of the order of billions of pounds. The vast majority of such costs and impacts (even more to developed societies) are due to water related catastrophes such as the geomorphic action of flowing water (including scouring of critical infrastructure, bed and bank destabilisation) and flooding. New tools and radically novel concepts are in need, to enable our society becoming more resilient. This presentation, emphasises the utility of inertial sensors in gaining new insights on the interaction of flow hydrodynamics with the granular surface at the particle scale and for near threshold flow conditions. In particular, new designs of the "smart-sphere" device are discussed with focus on the purpose specific sets of flume experiments, designed to identify the exact response of the particle resting at the bed surface for various below, near and above threshold flow conditions. New sets of measurements are presented for particle entrainment from a Lagrangian viewpoint. Further to finding direct application in addressing real world challenges in the water sector, it is shown that such novel sensor systems can also help the research community (both experimentalists and computational modellers) gain a better insight on the underlying processes governing granular dynamics.

  4. Liquid transfer and entrainment correlation for droplet-annular flow

    International Nuclear Information System (INIS)

    A correlation for the amount of entrained liquid in annular flow has been developed from a simple model and experimental data. There are basically two different regions of entrainment, namely, the entrance and quasi-equilibrium regions. The correlation for the equilibrium region is expressed in terms of the dimensionless gas flux, diameter, cand total liquid Reynolds number. The entrance effect is taken into account by an exponential relaxation function. It has been shown that this new model can satisfactorily correlate wide ranges of experimental data for water. Furthermore, the necessary distance for the development of entrainment is identified. These correlations, therefore, can supply accurate information on entrainment which has not been available previously

  5. Entrainment of a Synthetic Oscillator through Queueing Coupling

    Science.gov (United States)

    Hochendoner, Philip; Mather, William; Butzin, Nicholas; Ogle, Curtis

    2014-03-01

    Many biological systems naturally exhibit (often noisy) oscillatory patterns that are capable of being entrained by external stimuli, though the mechanism of entrainment is typically obscured by the complexity of native networks. A synthetic biology approach, where genetic programs are wired ``by hand,'' has proven useful in this regard. In the present study, we use a synthetic oscillator in Escherichia coli to demonstrate a novel and potentially widespread mechanism for biological entrainment: competition of proteins for degradation by common pathway, i.e. a entrainment by a bottleneck. To faithfully represent the discrete and stochastic nature of this bottleneck, we leverage results from a recent biological queueing theory, where in particular, the queueing theoretic concept of workload is discovered to simplify the analysis. NSF Award 1330180.

  6. 振动搅拌对混凝士耐久性的影响%The influence of vibrating mixing on the durability of concrete

    Institute of Scientific and Technical Information of China (English)

    付昌会; 冯忠绪; 张磊

    2011-01-01

    为了研究振动搅拌对混凝土耐久性的影响规律,通过测试分析不同搅拌条件和搅拌参数下混凝土的含气量和强度,分析比较不同振动方式对混凝土含气量的影响机理,并利用电镜照片和汞压法测试孔结构进行微观原理的分析.结果表明,除了目前国内外普遍采用的掺加引气剂的方法外,通过合理的搅拌方式,即混凝土搅拌机的搅拌叶片在强制搅拌物料的同时,也作为振动源对物料施以振动作用的振动搅拌方式,也可以显著提高混凝土的含气量;合适的振动搅拌可以使新拌混凝土含气量普遍达到3.5%左右,又具有较高的强度.微观原理的分析表明,振动搅拌可以促进混凝土中过渡层和水泥水化浆体的显微结构改善,还可以改善混凝土的孔结构分布,从而提高混凝土的强度和耐久性.%In order to determine the influence of vibrating mixing on concrete's durability, influencing mechanism of different vibrating ways on concrete's air content was compared and analyzed by testing and analyzing concrete's air content and concrete strength under different mixing conditions and mixing parameters, and microscopic pore structure was analyzed by using the electronic microscopy and mercury poromesitry. The results showed that besides adding air entraining agent used widely at home and abroad at present, adopting reasonable mixing method could also significantly improve concrete's air content, i.e. compulsively stirs and vibrates. By using the proper vibrating mixing method, the air content of fresh mixed concrete could reach about 3.5 percent in average and the concrete could obtain relatively high strength at the same time. The analysis of microscopic principle show that the vibrating mixing can promote the improvement of the microstructure of the concrete's transition layer and cement's hydration slurry, the pore distribution of concrete, that results in increasing the strength and durability of

  7. Entrainment Ranges for Chains of Forced Neural and Phase Oscillators.

    Science.gov (United States)

    Massarelli, Nicole; Clapp, Geoffrey; Hoffman, Kathleen; Kiemel, Tim

    2016-12-01

    Sensory input to the lamprey central pattern generator (CPG) for locomotion is known to have a significant role in modulating lamprey swimming. Lamprey CPGs are known to have the ability to entrain to a bending stimulus, that is, in the presence of a rhythmic signal, the CPG will change its frequency to match the stimulus frequency. Bending experiments in which the lamprey spinal cord has been removed and mechanically bent back and forth at a single point have been used to determine the range of frequencies that can entrain the CPG rhythm. First, we model the lamprey locomotor CPG as a chain of neural oscillators with three classes of neurons and sinusoidal forcing representing edge cell input. We derive a phase model using the connections described in the neural model. This results in a simpler model yet maintains some properties of the neural model. For both the neural model and the derived phase model, entrainment ranges are computed for forcing at different points along the chain while varying both intersegmental coupling strength and the coupling strength between the forcer and chain. Entrainment ranges for chains with nonuniform intersegmental coupling asymmetry are larger when forcing is applied to the middle of the chain than when it is applied to either end, a result that is qualitatively similar to the experimental results. In the limit of weak coupling in the chain, the entrainment results of the neural model approach the entrainment results for the derived phase model. Both biological experiments and the robustness of non-monotonic entrainment ranges as a function of the forcing position across different classes of CPG models with nonuniform asymmetric coupling suggest that a specific property of the intersegmental coupling of the CPG is key to entrainment. PMID:27091694

  8. Differential entrainment of neuroelectric delta oscillations in developmental dyslexia.

    Directory of Open Access Journals (Sweden)

    Fruzsina Soltész

    Full Text Available Oscillatory entrainment to the speech signal is important for language processing, but has not yet been studied in developmental disorders of language. Developmental dyslexia, a difficulty in acquiring efficient reading skills linked to difficulties with phonology (the sound structure of language, has been associated with behavioural entrainment deficits. It has been proposed that the phonological 'deficit' that characterises dyslexia across languages is related to impaired auditory entrainment to speech at lower frequencies via neuroelectric oscillations (<10 Hz, 'temporal sampling theory'. Impaired entrainment to temporal modulations at lower frequencies would affect the recovery of the prosodic and syllabic structure of speech. Here we investigated event-related oscillatory EEG activity and contingent negative variation (CNV to auditory rhythmic tone streams delivered at frequencies within the delta band (2 Hz, 1.5 Hz, relevant to sampling stressed syllables in speech. Given prior behavioural entrainment findings at these rates, we predicted functionally atypical entrainment of delta oscillations in dyslexia. Participants performed a rhythmic expectancy task, detecting occasional white noise targets interspersed with tones occurring regularly at rates of 2 Hz or 1.5 Hz. Both groups showed significant entrainment of delta oscillations to the rhythmic stimulus stream, however the strength of inter-trial delta phase coherence (ITC, 'phase locking' and the CNV were both significantly weaker in dyslexics, suggestive of weaker entrainment and less preparatory brain activity. Both ITC strength and CNV amplitude were significantly related to individual differences in language processing and reading. Additionally, the instantaneous phase of prestimulus delta oscillation predicted behavioural responding (response time for control participants only.

  9. Concrete works for Hamaoka No. 1 nuclear power plant

    International Nuclear Information System (INIS)

    Various aspects of concrete works performed for the reactor building of Hamaoka No.1 plant are reviewed. Control building and waste disposal building were all together combined with the reactor building in order to improve safety against earthquakes. Special consideration was given for the quality control of concrete works by establishing quality control committee, making quality control manual and by performing daily examination and monthly report. The quality and various materials of concrete used are described. The composition of concrete used for various parts of the building is also listed. Detailed description is made regarding the concrete placing for foundation mat, under a containment vessel, and the construction of air gaps and the placing of shielding concrete around the containment vessel. Curves representing the temperature history of concrete at various points are presented. As for testing, the items of test, methods of measurement, and the results of these test and measurement are presented in detail. (Aoki, K.)

  10. Development of various curing effect of nominal strength Geopolymer concrete

    Directory of Open Access Journals (Sweden)

    S. Kumaravel

    2014-04-01

    Full Text Available Geopolymer concrete is an innovative method and is produced by complete elimination of ordinary Portland cement byproduced in fly ash. This study on different condition of curing in geopolymer concrete suitable for curing at ambient and heat-cured condition of temperature will widen its application to concrete structures. Low lime fly ash is used as the base material, which is reacted by alkaline solution and additional use of ground granulated blast furnace slag. Workability of fresh concrete and compressive strength of geopolymer concrete was investigated. The curing effect of geopolymer concrete is steam, hot air and ambient cubes specimens are tested in different days. Results are compared for various curing and strength of concrete.

  11. Performance of Bridge Decks and Girders with Lightweight Aggregate Concrete

    OpenAIRE

    Ramirez, J.A.; Olek, J.; Rolle, Eric Joseph; Manlone, Brian J.

    2000-01-01

    Structural lightweight concrete is a very versatile material and Haydite and Minergy lightweight aggregates can be utilized in the mixture development of concrete for use in girders and decks in bridges. More widespread use of lightweight aggregates (LWA) would result in savings in construction cost due to considerable dead load reduction. The materials phase of this research study evaluated the fresh concrete properties (slump, unit weight, and air content), the mechanical properties of ha...

  12. Mechanical Properties of Fiber Reinforced Lightweight Concrete Containing Surfactant

    OpenAIRE

    Yoo-Jae Kim; Jiong Hu; Soon-Jae Lee; Byung-Hee You

    2010-01-01

    Fiber reinforced aerated lightweight concrete (FALC) was developed to reduce concrete's density and to improve its fire resistance, thermal conductivity, and energy absorption. Compression tests were performed to determine basic properties of FALC. The primary independent variables were the types and volume fraction of fibers, and the amount of air in the concrete. Polypropylene and carbon fibers were investigated at 0, 1, 2, 3, and 4% volume ratios. The lightweight aggregate used was made of...

  13. Influence of cracks on chloride penetration in concrete

    OpenAIRE

    Audenaert, K.; Schutter, G. de; MARSAVINA, L

    2009-01-01

    Chloride initiated reinforcement corrosion is the main durability problem for concrete structures in a marine environment. If the chlorides reach the reinforcement steel, it will depassivate and start to corrode in presence of air and water. Since the corrosion products have a larger volume than the initial products, concrete stresses are induced, leading to spalling and degradation of the concrete structures. If cracks, caused by early drying, thermal effects, shrinkage movements or overstre...

  14. Sustainable Concrete Technology

    Directory of Open Access Journals (Sweden)

    Sim J.

    2015-12-01

    Full Text Available The growing concern over global warming and significant ecological changes requires sustainable development in all fields of science and technology. Concrete not only consumes huge amount of energy and natural sources, but also emits large amount of CO2, mainly due to the production of cement. It is evident that such large amount of concrete production has put significant impact on the energy, resource, environment, and ecology of the society. Hence, how to develop the concrete technology in a sustainable way has become a significant issue. In this paper, some of Korean researches for sustainable development of concrete are presented. These are sustainable strengthening for deteriorated concrete structure, sustainable reinforcement of new concrete structure, sustainable concrete using recycled aggregate and supplementary cementing materials and finally application of each technique to precast concrete.

  15. concrete5 for developers

    CERN Document Server

    Uzayr, Sufyan bin

    2014-01-01

    Whether you have had some previous experience with concrete5 or are entirely new to it, this book will help you understand all that you need to know in order to get started with concrete5 development. A background in PHP is required; some knowledge of HTML/CSS is needed in order to fully grasp the concepts underlying concrete5 theme development.

  16. Deterioration of Concrete Structures

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    Chloride ingress is a common cause of deterioration of reinforced concrete bridges. Concrete may be exposed to chloride by seawater or de-icing salts. The chloride initiates corrosion of the reinforcement, which through expansion disrupts the concrete. In addition, the corrosion reduces the cross...

  17. Numerical study on onset of gas entrainment from free surface

    Energy Technology Data Exchange (ETDEWEB)

    Tomoaki Kunugi [Department of Nuclear engineering, Kyoto University, Yoshida Sakyou-ku Kyoto (Japan); Toshiki Ezure; Takaaki Sa ka; Kei Ito [Japan Nuclear Cycle Development Institute, 4002 Narita-cho, O-arai-cho Higashi-ibaraki-gun, 311- 1393 (Japan)

    2005-07-01

    Full text of publication follows: A fast breeder nuclear reactor (FBR) has an important role for closing a fuel cycle system in fission nuclear reactor systems. The liquid sodium cooling system of a latest compact FBR concept consists of two loops connected to a heat exchanger (HEX) and a pool-typed reactor vessel with the upper core structures (UCS). The high temperature sodium coolant comes from the reactor core to the vessel and flows through the hot legs towards the HEX. In order to design the compact FBR, it is necessary to clarify a criterion of a cover-gas entrainment from the coolant free surface of the vessel to the HEX through the hot leg. The surface velocity of the coolant in the vessel is considered as one of the key parameters of the gas entrainment phenomena: bubble entrained by free surface vortex, entraining bubbles caused by supercritical flows and gas entrainment by wave breaking. However, there is no clear quantitative explanation and criterion regarding the on-set condition of gas entrainment from the free surface until today. In the present study, numerical simulation of the gas entrainment and the bubble transport from free surface to the hot leg regarding the bubble entrainment due to the supercritical surface flows have been performed by means of the Multi-interface and Advection and Reconstruction Solver (MARS) and the numerical results are compared with that of the small scale fundamental experiments. The final goal of this study is to establish the evaluation procedure and criterion of these phenomena. Experiment performed by Moriya was chosen as the reference data for this comparison study. The test section consisted of an open-upped rectangular box with the inlet and outlet nozzles located at bottom of the box and almost a half height of the test section was filled with water. Resulting from these simulations, the gas entrainment phenomena were observed for both cases at certain flow conditions. In two-dimensional simulations, we found

  18. Numerical study on onset of gas entrainment from free surface

    International Nuclear Information System (INIS)

    Full text of publication follows: A fast breeder nuclear reactor (FBR) has an important role for closing a fuel cycle system in fission nuclear reactor systems. The liquid sodium cooling system of a latest compact FBR concept consists of two loops connected to a heat exchanger (HEX) and a pool-typed reactor vessel with the upper core structures (UCS). The high temperature sodium coolant comes from the reactor core to the vessel and flows through the hot legs towards the HEX. In order to design the compact FBR, it is necessary to clarify a criterion of a cover-gas entrainment from the coolant free surface of the vessel to the HEX through the hot leg. The surface velocity of the coolant in the vessel is considered as one of the key parameters of the gas entrainment phenomena: bubble entrained by free surface vortex, entraining bubbles caused by supercritical flows and gas entrainment by wave breaking. However, there is no clear quantitative explanation and criterion regarding the on-set condition of gas entrainment from the free surface until today. In the present study, numerical simulation of the gas entrainment and the bubble transport from free surface to the hot leg regarding the bubble entrainment due to the supercritical surface flows have been performed by means of the Multi-interface and Advection and Reconstruction Solver (MARS) and the numerical results are compared with that of the small scale fundamental experiments. The final goal of this study is to establish the evaluation procedure and criterion of these phenomena. Experiment performed by Moriya was chosen as the reference data for this comparison study. The test section consisted of an open-upped rectangular box with the inlet and outlet nozzles located at bottom of the box and almost a half height of the test section was filled with water. Resulting from these simulations, the gas entrainment phenomena were observed for both cases at certain flow conditions. In two-dimensional simulations, we found

  19. Final Report - "Foaming and Antifoaming and Gas Entrainment in Radioactive Waste Pretreatment and Immobilization Processes"

    Energy Technology Data Exchange (ETDEWEB)

    Wasan, Darsh T.

    2007-10-09

    The Savannah River Site (SRS) and Hanford site are in the process of stabilizing millions of gallons of radioactive waste slurries remaining from production of nuclear materials for the Department of Energy (DOE). The Defense Waste Processing Facility (DWPF) at SRS is currently vitrifying the waste in borosilicate glass, while the facilities at the Hanford site are in the construction phase. Both processes utilize slurry-fed joule-heated melters to vitrify the waste slurries. The DWPF has experienced difficulty during operations. The cause of the operational problems has been attributed to foaming, gas entrainment and the rheological properties of the process slurries. The rheological properties of the waste slurries limit the total solids content that can be processed by the remote equipment during the pretreatment and meter feed processes. Highly viscous material can lead to air entrainment during agitation and difficulties with pump operations. Excessive foaming in waste evaporators can cause carryover of radionuclides and non-radioactive waste to the condensate system. Experimental and theoretical investigations of the surface phenomena, suspension rheology and bubble generation of interactions that lead to foaming and air entrainment problems in the DOE High Level and Low Activity Radioactive Waste separation and immobilization processes were pursued under this project. The first major task accomplished in the grant proposal involved development of a theoretical model of the phenomenon of foaming in a three-phase gas-liquid-solid slurry system. This work was presented in a recently completed Ph.D. thesis (9). The second major task involved the investigation of the inter-particle interaction and microstructure formation in a model slurry by the batch sedimentation method. Both experiments and modeling studies were carried out. The results were presented in a recently completed Ph.D. thesis. The third task involved the use of laser confocal microscopy to study

  20. Turning Off Entrainment: The Role of Particle Size Distributions and Vent GeometryIn The Collapse of Volcanic Jets

    Science.gov (United States)

    Jessop, D.; Jellinek, M.; Roche, O.

    2014-12-01

    Volcanic jets can undergo gravitational collapse to produce pyroclastic density currents (PDCs), or loft material several tens of kilometres and spread out as an ash cloud. The key ingredient that determines which of these two phenomena will occur is the turbulent entrainment of atmospheric air, which adds buoyancy to the jet. Classical models of eruption columns assume that the rate of entrainment is fixed and ~10% of the upflow rate of the jet. In particular, the efficiency of entrainment is assumed to be independent of the vent shape as well as the physical properties of the pyroclastic mixture. However, we show that the presence of particles of certain particle-size distributions (PSDs) in the jet can have a significant effect on the entrainment rate owing to their buoyancy and inertia. As a consequence, the conditions for collapse as previously identified must be revisited. In particular, there is a possibility for an eruption to produce both a buoyant column and a collapsing fountain. Using scaled analogue experiments, we test the likelyhood of collapse and the production of pyroclastic flows according to the source geometry and particle-size distributions.

  1. Dynamic behavior of porous concretes under drop weight impact testing

    NARCIS (Netherlands)

    Agar Ozbek, A.S.; Weerheijm, J.; Schlangen, E.; Breugel, K. van

    2013-01-01

    Porous concrete is used as a construction material in various applications mainly as a permeable cementitious material. However, its response under impact loading is generally not considered. Due to the high percentage of its intentional meso-size air pores, porous concrete has a moderate static str

  2. COP Evaluation for a Membrane Liquid Desiccant Air Conditioning System Using Four Different Heating Equipment

    OpenAIRE

    Abdel-Salam, Ahmed; Simonson, Carey

    2015-01-01

    Liquid desiccant air conditioning (LDAC) is a promising technology in terms of energy efficiency, comfort and indoor air quality. The major components of a LDAC system are the dehumidifier and regenerator. The most commonly used design of dehumidifiers/regenerators is the packed-bed, which might result in the entrainment of desiccant droplets in air streams. A promising solution for the entrainment of desiccant droplets in air streams is to use a liquid-to-air membrane energy exchanger (LAMEE...

  3. Nonassociative learning promotes respiratory entrainment to mechanical ventilation.

    Directory of Open Access Journals (Sweden)

    Shawna M MacDonald

    Full Text Available BACKGROUND: Patient-ventilator synchrony is a major concern in critical care and is influenced by phasic lung-volume feedback control of the respiratory rhythm. Routine clinical application of positive end-expiratory pressure (PEEP introduces a tonic input which, if unopposed, might disrupt respiratory-ventilator entrainment through sustained activation of the vagally-mediated Hering-Breuer reflex. We suggest that this potential adverse effect may be averted by two differentiator forms of nonassociative learning (habituation and desensitization of the Hering-Breuer reflex via pontomedullary pathways. METHODOLOGY/PRINCIPAL FINDINGS: We tested these hypotheses in 17 urethane-anesthetized adult Sprague-Dawley rats under controlled mechanical ventilation. Without PEEP, phrenic discharge was entrained 1:1 to the ventilator rhythm. Application of PEEP momentarily dampened the entrainment to higher ratios but this effect was gradually adapted by nonassociative learning. Bilateral electrolytic lesions of the pneumotaxic center weakened the adaptation to PEEP, whereas sustained stimulation of the pneumotaxic center weakened the entrainment independent of PEEP. In all cases, entrainment was abolished after vagotomy. CONCLUSIONS/SIGNIFICANCE: Our results demonstrate an important functional role for pneumotaxic desensitization and extra-pontine habituation of the Hering-Breuer reflex elicited by lung inflation: acting as buffers or high-pass filters against tonic vagal volume input, these differentiator forms of nonassociative learning help to restore respiratory-ventilator entrainment in the face of PEEP. Such central sites-specific habituation and desensitization of the Hering-Breuer reflex provide a useful experimental model of nonassociative learning in mammals that is of particular significance in understanding respiratory rhythmogenesis and coupled-oscillator entrainment mechanisms, and in the clinical management of mechanical ventilation in

  4. Entrainment and deposition modeling of liquid films with applications for BWR fuel rod dryout

    Science.gov (United States)

    Ratnayake, Ruwan Kumara

    While best estimate computer codes provide the licensing basis for nuclear power facilities, they also serve as analytical tools in overall plant and component design procedures. An ideal best estimate code would comprise of universally applicable mechanistic models for all its components. However, due to the limited understanding in these specific areas, many of the models and correlations used in these codes reflect high levels of empiricism. As a result, the use of such models is strictly limited to the range of parameters within which the experiments have been conducted. Disagreements between best estimate code predictions and experimental results are often explained by the mechanistic inadequacies of embedded models. Significant mismatches between calculated and experimental critical power values are common observations in the analyses of Boiling Water Reactors (BWR). Based on experimental observations and calculations, these mismatches are attributed to the additional entrainment and deposition caused by spacer grids in BWR fuel assemblies. In COBRA-TF (Coolant Boiling in Rod Arrays-Two Fluid); a state of the art industrial best estimate code, these disagreements are hypothesized to occur due the absence of an appropriate spacer grid model. In this thesis, development of a suitably detailed spacer grid model and integrating it to COBRA-TF is documented. The new spacer grid model is highly mechanistic so that the applicability of it is not seriously affected by geometric variations in different spacer grid designs. COBRA-TF (original version) simulations performed on single tube tests and BWR rod bundles with spacer grids showed that single tube predictions were more accurate than those of the rod bundles. This observation is understood to arise from the non-availability of a suitable spacer grid model in COBRA-TF. Air water entrainment experiments were conducted in a test section simulating two adjacent BWR sub channels to visualize the flow behavior at

  5. Application of lightweight aggregate concrete to canal lining in cold regions%轻骨料混凝土在寒区渠道衬砌中的应用

    Institute of Scientific and Technical Information of China (English)

    董伟; 申向东; 郭克贞; 田德龙; 俞婷婷; 何静

    2016-01-01

    为研究浮石轻骨料混凝土作为渠道衬砌材料的可行性,采用天然浮石、砂、水泥、水以及工业废料粉煤灰制作浮石轻骨料混凝土渠道衬砌板,与无衬砌渠道及普通混凝土衬砌渠道进行渠床基土温度的比较;同时,利用图像处理软件对比分析普通混凝土截面与浮石轻骨料混凝土截面的形貌特征。结果表明:浮石轻骨料混凝土衬砌可以有效减缓基土与外界的热交换速度,使基土在整个冻结期温度变化缓慢,基土冻结延迟或不发生冻结;在引气剂用量相同的情况下,浮石轻骨料混凝土可见封闭孔的数量在整个截面所占面积比例远大于普通骨料混凝土。%In order to investigate the feasibility of using pumice lightweight aggregate concrete as channel lining material, a canal lining board of pumice lightweight aggregate concrete was produced using natural pumice, sand, cement, water, and industrial waste fly ash. The foundation soil temperatures of an unlined canal, a normal concrete-lined canal, and a pumice lightweight aggregate concrete-lined canal were compared. Meanwhile, the morphology characteristics of the normal concrete cross-section and the pumice lightweight aggregate concrete cross-section were compared using image-processing software . The results indicate that the pumice lightweight aggregate concrete lining can effectively slow down the rate of heat exchange between the foundation soil and surrounding environment, inducing that the foundation soil temperature changes slowly throughout the freezing period and foundation soil congelation delays or does not occur. The proportion of the area of visible closed holes of pumice lightweight aggregate concrete to the whole cross-section area is far greater than that of normal concrete in the case of the same amount of air-entraining agent.

  6. Oxy-coal combustion in an entrained flow reactor: Application of specific char and volatile combustion and radiation models for oxy-firing conditions

    DEFF Research Database (Denmark)

    Álvarez, L.; Yin, Chungen; Riaza, J.;

    2013-01-01

    implemented in CFD (Computational Fluid Dynamics) simulations of combustion of three coals under air-firing and various oxy-firing (21-35% vol O2 in O2/CO2 mixture) conditions in an EFR (entrained flow reactor). The predicted coal burnouts and gaseous emissions were compared against experimental results...

  7. Autogenous Deformation of Concrete

    DEFF Research Database (Denmark)

    Autogenous deformation of concrete can be defined as the free deformation of sealed concrete at a constant temperature. A number of observed problems with early age cracking of high-performance concretes can be attributed to this phenomenon. During the last 10 years , this has led to an increased...... focus on autogenous deformation both within concrete practice and concrete research. Since 1996 the interest has been significant enough to hold international, yearly conferences entirely devoted to this subject. The papers in this publication were presented at two consecutive half-day sessions...... at the American Concrete Institute’s Fall Convention in Phoenix, Arizona, October 29, 2002. All papers have been reviewed according to ACI rules. This publication, as well as the sessions, was sponsored by ACI committee 236, Material Science of Concrete. The 12 presentations from 8 different countries indicate...

  8. Recycled Concrete as Aggregate for Structural Concrete Production

    OpenAIRE

    Mirjana Malešev; Vlastimir Radonjanin; Snežana Marinković

    2010-01-01

    A comparative analysis of the experimental results of the properties of fresh and hardened concrete with different replacement ratios of natural with recycled coarse aggregate is presented in the paper. Recycled aggregate was made by crushing the waste concrete of laboratory test cubes and precast concrete columns. Three types of concrete mixtures were tested: concrete made entirely with natural aggregate (NAC) as a control concrete and two types of concrete made with natural fine and recycle...

  9. Gas entrainment in scaled model of pool type LMFBR

    Energy Technology Data Exchange (ETDEWEB)

    Banerjee, I.; Chandra, L.; Laxman, D.; Kumar, A.; Gopal, C.A.; Shivakumar, N.S.; Padmakumar, G.; Anand Babu, C.; Vaidyanathan, G. [Fast Reactor Technology Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamil Nadu (India)

    2007-07-01

    The reactor Thermal hydraulics plays an important role for successful operation of Prototype Fast Breeder Reactor (PFBR), which is under construction at Kalpakkam, India. One of the issues to be resolved in PFBR is argon cover gas entrainment problem from free liquid sodium surface. The entrained cover gas may hinder the normal reactor operation. High free surface velocity along with the presence of various immersed components in the hot pool is the cause of gas entrainment from free surface. To reduce the free surface velocity and hence gas entrainment, ring type baffle plates were considered. Initially the optimum geometry of the baffle plate was arrived through numerical analysis using PHOENICS, a commercial computational fluid dynamics tool. Finally the experiments were conducted in a 1/4 scale water model of PFBR primary circuit with selected baffle plate geometry. It was found that a baffle plate with radial width of 125 mm in the model and located above intermediate heat exchanger is very effective to reduce the gas entrainment problem in PFBR. (authors)

  10. CFD Approaches for Modelling Bubble Entrainment by an Impinging Jet

    Directory of Open Access Journals (Sweden)

    Martin Schmidtke

    2009-01-01

    Full Text Available This contribution presents different approaches for the modeling of gas entrainment under water by a plunging jet. Since the generation of bubbles happens on a scale which is smaller than the bubbles, this process cannot be resolved in meso-scale simulations, which include the full length of the jet and its environment. This is why the gas entrainment has to be modeled in meso-scale simulations. In the frame of a Euler-Euler simulation, the local morphology of the phases has to be considered in the drag model. For example, the gas is a continuous phase above the water level but bubbly below the water level. Various drag models are tested and their influence on the gas void fraction below the water level is discussed. The algebraic interface area density (AIAD model applies a drag coefficient for bubbles and a different drag coefficient for the free surface. If the AIAD model is used for the simulation of impinging jets, the gas entrainment depends on the free parameters included in this model. The calculated gas entrainment can be adapted via these parameters. Therefore, an advanced AIAD approach could be used in future for the implementation of models (e.g., correlations for the gas entrainment.

  11. 桥梁高性能清水混凝土研究与应用%Research and application of high performance bridge fair-faced concrete

    Institute of Scientific and Technical Information of China (English)

    何小宇; 周孝军

    2014-01-01

    根据成都市二环路高架桥与广巴高速公路防撞护栏工程清水混凝土的设计与施工要求,采用密实骨架堆积理论进行了清水混凝土配合比优化设计,研究了外加剂组成与掺量、浇筑与振捣工艺等对混凝土外观质量的影响,得到了消泡剂与引气剂的合理掺量,确定了各施工过程的最佳工艺,并在依托工程中成功应用,制备出具有色泽均匀、美观的镜面效果的清水混凝土。%According to the concrete requirement of design and construction of the Second Ring Road viaduct project in chengdu and Guang-Ba highway guardrail,theosry of dense framework packing was used for the optimization design of concrete mix proportion,and the effect of admix-ture composition and content,pouring and vibrating technology on the appearance of hardened concrete were studied. The reasonable dosage of defoamer agent and air entraining agent were got. The optimal process was ascertained in each of the construction process,which have success-fully applied in practical engineering,and the fair-faced concrete with a series of advantages such as uniform color and mirror effect have pre-pared.

  12. Transport, Evolution and Entrainment of Asian Dust/Pollution into the Pacific Marine Boundary

    Science.gov (United States)

    Clarke, A. D.; McNaughton, C. S.; Kapustin, V.; Vetter, O.; Dibb, J. E.; Anderson, B. E.; Browell, E. V.; Carmichael, G.; Landing, B.

    2007-05-01

    Various airborne and ship based studies over the past several years have allowed us to measure Asian dust and pollution aerosol from near its source to locations up to 10,000km downwind where it was entrained into the marine boundary layer (MBL). Dust was found to accumulate up to half of the soluble species such as sulfate and nitrate during passage through pollution regions in Asia before being lofted into the free troposphere near Japan. At times, transport in the free troposphere included regions of subsidence in high pressure regions that brought these "rivers" of dust and pollution down to the top of the MBL. Shipboard measurements and lidar data indicated both clear air entrainment and convective activity, associated with the passage of low pressure systems, facilitated dust transport through the inversion. High temperature volatilization of particles in the MBL up to 900C was used to remove most sulfates, nitrates, carbon and sea-salt to leave only dust measured and sized by an optical particle counter. These shipboard data and concurrent chemical measurements revealed the relation between entrainment of pollution and dust into the MBL associated with passage of high pressure systems. Subsequent passage of low pressure systems also revealed scavenging and removal of aerosol through precipitation to the ocean surface. This process appears to be a common removal pathway for dust over the Pacific and a mechanism for supplying the ocean surface with soluble iron and aluminum to the ocean surface. Measurements in the free troposphere and MBL also captured various aspects of these processes. Airborne missions flown north of Hawaii during the NASA PEM-Tropics and IMPEX missions characterized the vertical structure of subsiding dust and pollution. In-flight mapping of the dust/pollution layers and structure using the NASA Langley DIAL LIDAR show a sloping, subsiding Asian air-mass entraining into the marine boundary layer (MBL). In-situ measurements of the aerosol

  13. Resolving both entrainment-mixing and number of activated CCN in deep convective clouds

    Directory of Open Access Journals (Sweden)

    E. Freud

    2011-12-01

    Full Text Available The number concentration of activated CCN (Na is the most fundamental microphysical property of a convective cloud. It determines the rate of droplet growth with cloud depth and conversion into precipitation-sized particles and affects the radiative properties of the clouds. However, measuring Na is not always possible, even in the cores of the convective clouds, because entrainment of sub-saturated ambient air deeper into the cloud lowers the concentrations by dilution and may cause partial or total droplet evaporation, depending on whether the mixing is homogeneous or extreme inhomogeneous, respectively.

    Here we describe a methodology to derive Na based on the rate of cloud droplet effective radius (Re growth with cloud depth and with respect to the cloud mixing with the entrained ambient air. We use the slope of the tight linear relationship between the adiabatic liquid water mixing ratio and Re3 (or Rv3 to derive an upper limit for Na assuming extreme inhomogeneous mixing. Then we tune Na down to find the theoretical relative humidity that the entrained ambient air would have for each horizontal cloud penetration, in case of homogeneous mixing. This allows us to evaluate both the entrainment and mixing process in the vertical dimension in addition to getting a better estimation for Na.

    We found that the derived Na from the entire profile data is highly correlated with the independent CCN measurements from below cloud base. Moreover, it was found that mixing of sub-saturated ambient air into the cloud at scales of ~100 m and above is inclined towards the extreme inhomogeneous limit, i.e. that the time scale of droplet evaporation is significantly smaller than that for turbulent mixing. This means that ambient air that entrains

  14. Lunar concrete: Prospects and challenges

    Science.gov (United States)

    Khitab, Anwar; Anwar, Waqas; Mehmood, Imran; Kazmi, Syed Minhaj Saleem; Munir, Muhammad Junaid

    2016-02-01

    The possibility of using concrete as a construction material at the Moon surface is considered. Dissimilarities between the Earth and the Moon and their possible effects on concrete are also emphasized. Availability of constituent materials for concrete at lunar surface is addressed. An emphasis is given to two types of materials, namely, hydraulic concrete and sulfur concrete. Hydraulic concrete necessitates the use of water and sulfur concrete makes use of molten sulfur in lieu of cement and water.

  15. Mix proportion design of anti-freezing and anti-permeability low-strength concrete and its corresponding mechanical properties%低强度抗冻抗渗混凝土配合比设计及其力学特性

    Institute of Scientific and Technical Information of China (English)

    彭辉; 杨海宁; 刘绍林

    2012-01-01

    Through carefully choosing the mix proportion design of low-strength concrete,the anti-freezing,anti-perme- ability and mechanical properties of concrete were studied. The effects of optimal water-to-cement ratio, mixing amount of air-entraining agent on anti-freezing and anti-permeability characteristics of concrete were researched. Furthermore, the compressive strength of concrete under condition of saturated situation and natural curing were also studied respec- tively. The researches show that by using of mixing proper amount of air-entraining agent and choosing suitable water- to-cement ratio, the anti-freezing and anti-permeability of low-strength concrete can be obviously improved without re- ducing concrete strength and anti-permeability properties in severe cold areas in China.%通过对低强度混凝土配合比进行优化设计,并开展混凝土的抗冻、抗渗和力学等性能的试验研究。分别研究了最优水灰比、引气剂掺量等因素对混凝土抗冻性能的影响,并在上述条件下研究了其对强度和抗渗等性能的影响,以及饱和与自然养护条件下混凝土抗压强度变化特点。结果证明:在严寒地区,在满足工程结构混凝土强度和抗渗要求的情况下,即使配制低强度混凝土,通过掺适量引气剂和选用适当的水灰比能显著提高低强度混凝土在高寒干燥地区的抗冻耐久性。

  16. On robustness of phase resetting to cell division under entrainment.

    Science.gov (United States)

    Ahmed, Hafiz; Ushirobira, Rosane; Efimov, Denis

    2015-12-21

    The problem of phase synchronization for a population of genetic oscillators (circadian clocks, synthetic oscillators, etc.) is considered in this paper, taking into account a cell division process and a common entrainment input in the population. The proposed analysis approach is based on the Phase Response Curve (PRC) model of an oscillator (the first order reduced model obtained for the linearized system and inputs with infinitesimal amplitude). The occurrence of cell division introduces state resetting in the model, placing it in the class of hybrid systems. It is shown that without common entraining input in all oscillators, the cell division acts as a disturbance causing phase drift, while the presence of entrainment guarantees boundedness of synchronization phase errors in the population. The performance of the obtained solutions is demonstrated via computer experiments for two different models of circadian/genetic oscillators (Neurospora׳s circadian oscillation model and the repressilator).

  17. A model for droplet entrainment rate in horizontal stratified flow

    International Nuclear Information System (INIS)

    This work proposes an original approach for modeling the entrainment of droplets in a horizontal stratified two-phase wavy flows. This mechanistic model is based on the ripple-waves breakout and entrainment phenomenon by estimating the liquid mass pulled off the wave crests during their fragmentation. The paper presents the modeling procedure for estimating the wavelength of these ripples and the related entrained liquid volume. In regards to these parameters, it is shown that a relatively simple methodology can be obtained to ease the implementation in a system code. This work aims at substituting the current existing empirical correlations in the system code CATHARE 3 by using a flowfield for a liquid dispersed phase. (author)

  18. Saturation point representation of cloud-top entrainment instability

    Science.gov (United States)

    Boers, Reinout

    1991-01-01

    Cloud-top entrainment instability was investigated using a mixing line analysis. Mixing time scales are closely related to the actual size of the parcel, so that local instabilities are largely dependent on the scales of mixing near the cloud top. Given a fixed transport velocity, variation over a small range of parcel length scales (parcel mixing velocities) turns an energy-producing mixing process into an energy-consuming mixing process. It is suggested that a single criterion for cloud-top entrainment instability will not be found due to the role of at least three factors operating more or less independently; the stability of the mixing line, the entrainment speed, and the strength of the internal boundary-layer circulation.

  19. Entrainment of ichthyoplankton and larval fishes during cooling water withdrawal

    International Nuclear Information System (INIS)

    Plantonic fish eggs and larvae are entrained into the Savannah River Plant (SRP) pumping system as Savannah River water is withdrawn for cooling purposes. The American shad contributed 96% of the planktonic fish eggs collected in the Savannah River. Eggs were rare in plankton samples from the intake canals and were assumed to have settled to the bottom as current velocity was reduced in the canal entrance. An estimated 72 million fish eggs were transported past the intake canals. Assuming ''worst case conditions,'' 6.8 million eggs (9.5%) could have been lost due to entrainment. Blueback herring comprised nearly one-half of the 216 million fish larvae susceptible to impact. Spotted sucker and black crappie were also common among the 22 species of fish larvae collected. An estimated 19.6 million (9.1%) fish larvae could have been entrained under ''worst case conditions''

  20. Entrained flow gasification of coal/bio-oil slurries

    DEFF Research Database (Denmark)

    Feng, Ping; Lin, Weigang; Jensen, Peter Arendt;

    2016-01-01

    Coal/bio-oil slurry (CBS) is a new partial green fuel for bio-oil utilization. CBS reacts with gasification agents at high temperatures and converts into hydrogen and carbon monoxide. This paper provides a feasibility study for the gasification of CBS in an atmospheric entrained flow reactor...... for syngas production. Experiments have shown that CBS can be successfully processed and gasified in the entrained flow reactor to produce syngas with almost no tar content and low residual carbon formation. High reactor temperature and steam/carbon ratio is favourable for H2 production. At 1400 °C...

  1. Evidence for Little Shallow Entrainment in Starting Mantle Plumes

    Science.gov (United States)

    Lohmann, F. C.; Phipps Morgan, J.; Hort, M.

    2005-12-01

    Basalts from intraplate or hotspot ocean islands show distinct geochemical signatures. Their diversity in composition is generally believed to result from the upwelling plume entraining shallow mantle material during ascent, while potentially also entraining other deep regions of the mantle. Here we present results from analogue laboratory experiments and numerical modelling that there is evidence for little shallow entrainment into ascending mantle plumes, i.e. most of the plume signature is inherited from the source. We conducted laboratory experiments using glucose syrup contaminated with glass beads to visualize fluid flow and origin. The plume is initiated by heating from below or by injecting hot, uncontaminated syrup. Particle movement is captured by a CCD camera. In our numerical experiments we solve the Stokes equations for a viscous fluid at infinite Prandtl number with passive tracer particles being used to track fluid flow and entrainment rates, simulating laboratory as well as mantle conditions. In both analogue experiments and numerical models we observe the classical plume structure being embedded in a `sheath' of material from the plume source region that retains little of the original temperature anomaly of the plume source. Yet, this sheath ascends in the `slipstream' of the plume at speeds close to the ascent speed of the plume head, and effectively prevents the entrainment of surrounding material into the plume head or plume tail. We find that the source region is most effectively sampled by an ascending plume and that compositional variations in the source region are preserved during plume ascent. The plume center and plume sheath combined are composed of up to 85% source material. However, there is also evidence of significant entrainment of up to 30% of surrounding material into the outer layers of the plume sheath. Entrainment rates are found to be influenced by mantle composition and structure, with the radial viscosity profile of the

  2. Inspection method and self-compactability of high fluidity concrete in a model of sandwich composite structure construction

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Hideki; Nishida, Noriyuki [Research and Technology Institute, Nishimatsu Construction, Co., Ltd., Yamato, Kanagawa (Japan); Sonoyama, Tetsuo [Ministry of Transportation, Kobe, Hyogo (Japan); Jodai, Takaharu [Ministry of Transportation, Osaka (Japan)

    2000-06-01

    High fluidity concrete was applied for sandwich composite structure of immersed tunnel elements. This work requires inspection method for self-compactability of concrete and reliable techniques for concrete filling into the steel-shells of sandwich composite structure, because of difficulty to monitor placed concrete. The authors tried to study them on full-scale models. As a result, the authors confirmed self-compactability of concrete and selected concreting method to increase the degree of filling. Then the authors selected the method combining the radioisotope method by {gamma} ray to measure depth of air void, and a hammer test to estimate distribution of air voids. (author)

  3. Behaviour of Recycled Coarse Aggregate Concrete: Age and Successive Recycling

    Science.gov (United States)

    Sahoo, Kirtikanta; Pathappilly, Robin Davis; Sarkar, Pradip

    2016-06-01

    Recycled Coarse Aggregate (RCA) concrete construction technique can be called as `green concrete', as it minimizes the environmental hazard of the concrete waste disposal. Indian standard recommends target mean compressive strength of the conventional concrete in terms of water cement ratio ( w/ c). The present work is an attempt to study the behaviour of RCA concrete from two samples of parent concrete having different age group with regard to the relationship of compressive strength with water cement ratios. Number of recycling may influence the mechanical properties of RCA concrete. The influence of age and successive recycling on the properties such as capillary water absorption, drying shrinkage strain, air content, flexural strength and tensile splitting strength of the RCA concrete are examined. The relationship between compressive strength at different w/ c ratios obtained experimentally is investigated for the two parameters such as age of parent concrete and successive recycling. The recycled concrete using older recycled aggregate shows poor quality. While the compressive strength reduces with successive recycling gradually, the capillary water absorption increases abruptly, which leads to the conclusion that further recycling may not be advisable.

  4. Test of dust scattering caused by dumpling of concrete materials

    International Nuclear Information System (INIS)

    The behaviors of dust at the disposal of low-level radioactive concrete waste were investigated for making an estimation of exposure dose of the workers who inhale a contaminated dust in the air. Dust concentration and it's particle size in the air caused by the dumping test of mock concrete materials were measured. The concrete dusts scatter usually by grinding, cutting, and blasting of a lump of concrete. Three test concrete samples of different sizes, such as particulate (crushed stone), broken concrete (small pieces of about 5 mm - 20 cm), and broken concrete (large pieces of about 30 cm) were used in the dumping test. Concentrations of suspended and respirable dust (< 10 μm) in the air were measured by digital aerosol monitors and dust samplers which were located at 4 - 10 m distant from a dropping center. A testing house was built for avoiding from the effects of environment, such as wind direction and wind velocity. The test samples were dropped on the surface of steel plate from about 1 meter height at a low and a high wind condition. In case of the particulate test sample, the dropping height and the wind velocity affected to the dust concentration in the air. The dust scattering was largely suppressed by the uses of water sprinkling, suppression sheet and wet test sample. (Suetake, M.)

  5. Concrete bridge prioritization system

    OpenAIRE

    Kesselring, Debbie Anne

    1995-01-01

    An alternative method of prioritization for concrete bridge maintenance, repair, and rehabilitation activities is required due to the inability of the current system to manage the increasing nmnber of aging concrete bridges. The Concrete Bridge Prioritization System was proposed because of its ability to address the critical technical parameters of safety and cost benefit in prioritization of funding and work allocation. The analysis includes four parts, service life assessment, s...

  6. Physical modelling and scale effects of air-water flows on stepped spillways

    Institute of Scientific and Technical Information of China (English)

    CHANSON Hubert; GONZALEZ Carlos A.

    2005-01-01

    During the last three decades, the introduction of new construction materials (e.g. RCC (Roller Compacted Concrete),strengthened gabions) has increased the interest for stepped channels and spillways. However stepped chute hydraulics is not simple, because of different flow regimes and importantly because of very-strong interactions between entrained air and turbulence. In this study, new air-water flow measurements were conducted in two large-size stepped chute facilities with two step heights in each facility to study experimental distortion caused by scale effects and the soundness of result extrapolation to prototypes. Experimental data included distributions of air concentration, air-water flow velocity, bubble frequency, bubble chord length and air-water flow turbulence intensity. For a Froude similitude, the results implied that scale effects were observed in both facilities, although the geometric scaling ratio was only Lr=2 in each case. The selection of the criterion for scale effects is a critical issue. For example, major differences (i.e. scale effects) were observed in terms of bubble chord sizes and turbulence levels although little scale effects were seen in terms of void fraction and velocity distributions. Overall the findings emphasize that physical modelling of stepped chutes based upon a Froude similitude is more sensitive to scale effects than classical smooth-invert chute studies, and this is consistent with basic dimensional analysis developed herein.

  7. Concrete portable handbook

    CERN Document Server

    Woodson, R Dodge

    2011-01-01

    Whether or not, you are on the job site or back in the office, this book will help you to avoid mistakes, code violations, and wasted time and money. The book's four part treatment begins with constituent materials followed by self contained parts on Concrete Properties, Processes, and Concrete Repair and Rehabilitation. Designed to be an ""all in one"" reference, the author includes a wealth information for the most popular types of testing. This includes: Analysis of Fresh Concrete; Testing Machines; Accelerated Testing Methods; Analysis of Hardened Concrete and Mortar; Core Sampl

  8. Gas and Water Permeability of Concrete

    Energy Technology Data Exchange (ETDEWEB)

    Villar, M. V.; Martin, P. L.; Romero, F. J.; Gutierrez-Rodirgo, V.; Barcala, J. M.

    2012-11-01

    The gas pressure of concrete samples was measured in an unsteady-state equipment working under low injection pressures and in a newly fine tuned steady-state setup working under different pressures. These measurements allowed the estimation of the intrinsic and relative gas permeability of the concrete and of the effect of boundary conditions on them. Permeability decreased with water content, but it was also greatly affected by the hydraulic history of concrete, i.e. if it had been previously dried or wetted. In particular, and for a given degree of saturation, the gas permeability of concrete previously saturated was lower than if the concrete had been just air dried or saturated after air drying. In any case, the gas permeability was about two orders of magnitude higher than the liquid water permeability (10-16 vs. 10-18 m2), probably due to the chemical reactions taking place during saturation (carbonation). The relative gas permeability of concrete increased sharply for water degrees of saturation smaller than 50%. The boundary conditions also affected the gas permeability, which seemed to be mostly conditioned by the back pressure and the confining pressure, increasing as the former increased and decreasing as the latter increased, i.e. decreasing as the effective pressure increased. Overall the increase of pressure head or injection pressure implied a decrease in gas permeability. External,microcracking during air-drying could not be ruled out as responsible for the decrease of permeability with confining pressure. The apparent permeability obtained applying the Klinkenberg method for a given effective pressure was only slightly smaller than the average of all the values measured for the same confining pressure range. For this reason it is considered that the Klinkenberg effect was not relevant in the range of pressures applied. (Author) 37 refs.

  9. Queueing-Based Synchronization and Entrainment for Synthetic Gene Oscillators

    Science.gov (United States)

    Mather, William; Butzin, Nicholas; Hochendoner, Philip; Ogle, Curtis

    Synthetic gene oscillators have been a major focus of synthetic biology research since the beginning of the field 15 years ago. They have proven to be useful both for biotechnological applications as well as a testing ground to significantly develop our understanding of the design principles behind synthetic and native gene oscillators. In particular, the principles governing synchronization and entrainment of biological oscillators have been explored using a synthetic biology approach. Our work combines experimental and theoretical approaches to specifically investigate how a bottleneck for protein degradation, which is present in most if not all existing synthetic oscillators, can be leveraged to robustly synchronize and entrain biological oscillators. We use both the terminology and mathematical tools of queueing theory to intuitively explain the role of this bottleneck in both synchronization and entrainment, which extends prior work demonstrating the usefulness of queueing theory in synthetic and native gene circuits. We conclude with an investigation of how synchronization and entrainment may be sensitive to the presence of multiple proteolytic pathways in a cell that couple weakly through crosstalk. This work was supported by NSF Grant #1330180.

  10. Efficiency of brainwave entrainment by binaural beats in reducing anxiety

    Directory of Open Access Journals (Sweden)

    Ahmad Alipoor

    2014-04-01

    Full Text Available Background: Anxiety is a fundamental phenomenon that is a common symptom in all mental disorders. The aim of the present study was to assess the effect of brainwave entrainment on anxiety reduction using binaural beats. Methods: In this experimental double-blind study, 30 employees were selected from an engineering research firm through random sampling and replacement and divided into two groups: control group and experimental group. All participants completed the Spielberger’s State-Trait Anxiety Inventory (STAI. Then, the experimental group listened to binaural beats which was recorded on a non-vocal piece of music for 4 weeks, 3 sessions each week. Each session lasted about 20 minutes. At the same time, the control group listened to the background music without any entrainment sound. At the end, both groups completed the anxiety questionnaire and the anxiety scores of both groups obtained before and after intervention were analyzed by ANCOVA. Results: The findings showed that the brainwave entrainment using binaural beats led to the significant reduction of state anxiety (P<0.001 and trait anxiety (P<0.018. Conclusion: Brainwave entrainment using binaural beats is an effective factor in decreasing state and trait anxiety; so, it can be used to reduce anxiety in mental health centers.

  11. Characterization of Residual Particulates from Biomass Entrained Flow Gasification

    DEFF Research Database (Denmark)

    Qin, Ke; Lin, Weigang; Fæster, Søren;

    2013-01-01

    Biomass gasification experiments were carried out in a bench scale entrained flow reactor, and the produced solid particles were collected by a cyclone and a metal filter for subsequent characterization. During wood gasification, the major part of the solid material collected in the filter is soot...

  12. EFFECTS OF CONTINUOUS CHLORINATION ON ENTRAINED ESTUARINE PLANKTON

    Science.gov (United States)

    The effects of continuous chlorination on entrained plankton are investigated in tests using running sea water and adenosine triphosphate (ATP) as an indicator of biomass. Effects were measured by bioluminescence with the use of luciferin-luciferase reagents from firefly lanterns...

  13. Radon emanation fractions from concretes containing fly ash and metakaolin

    Energy Technology Data Exchange (ETDEWEB)

    Taylor-Lange, Sarah C., E-mail: taylorlanges@utexas.edu [Department of Civil, Architectural, and Environmental Engineering, 1 University Station C1748, The University of Texas at Austin, Austin, TX 78712 (United States); Juenger, Maria C.G. [Department of Civil, Architectural, and Environmental Engineering, 1 University Station C1748, The University of Texas at Austin, Austin, TX 78712 (United States); Siegel, Jeffrey A. [Department of Civil, Architectural, and Environmental Engineering, 1 University Station C1748, The University of Texas at Austin, Austin, TX 78712 (United States); Department of Civil Engineering, 35 St. George Street, University of Toronto, Toronto, ON, M5S 1A4 (Canada)

    2014-01-01

    Radon ({sup 222}Rn) and progenies emanate from soil and building components and can create an indoor air quality hazard. In this study, nine concrete constituents, including the supplementary cementitious materials (SCMs) fly ash and metakaolin, were used to create eleven different concrete mixtures. We investigated the effect of constituent radium specific activity, radon effective activity and emanation fraction on the concrete emanation fraction and the radon exhalation rate. Given the serious health effects associated with radionuclide exposure, experimental results were coupled with Monte Carlo simulations to demonstrate predictive differences in the indoor radon concentration due to concrete mixture design. The results from this study show that, on average, fly ash constituents possessed radium specific activities ranging from 100 Bq/kg to 200 Bq/kg and emanation fractions ranging from 1.1% to 2.5%. The lowest emitting concrete mixture containing fly ash resulted in a 3.4% reduction in the concrete emanation fraction, owing to the relatively low emanation that exists when fly ash is part of concrete. On average, the metakaolin constituents contained radium specific activities ranging from 67 Bq/kg to 600 Bq/kg and emanation fractions ranging from 8.4% to 15.5%, and changed the total concrete emanation fraction by roughly ± 5% relative to control samples. The results from this study suggest that SCMs can reduce indoor radon exposure from concrete, contingent upon SCM radionucleotide content and emanation fraction. Lastly, the experimental results provide SCM-specific concrete emanation fractions for indoor radon exposure modeling. - Highlights: • Fly ash or metakaolin SCMs can neutralize or reduce concrete emanation fractions. • The specific activity of constituents is a poor predictor of the concrete emanation fraction. • Exhalation from fly ash concretes represents a small fraction of the total indoor radon concentration.

  14. Radon emanation fractions from concretes containing fly ash and metakaolin

    International Nuclear Information System (INIS)

    Radon (222Rn) and progenies emanate from soil and building components and can create an indoor air quality hazard. In this study, nine concrete constituents, including the supplementary cementitious materials (SCMs) fly ash and metakaolin, were used to create eleven different concrete mixtures. We investigated the effect of constituent radium specific activity, radon effective activity and emanation fraction on the concrete emanation fraction and the radon exhalation rate. Given the serious health effects associated with radionuclide exposure, experimental results were coupled with Monte Carlo simulations to demonstrate predictive differences in the indoor radon concentration due to concrete mixture design. The results from this study show that, on average, fly ash constituents possessed radium specific activities ranging from 100 Bq/kg to 200 Bq/kg and emanation fractions ranging from 1.1% to 2.5%. The lowest emitting concrete mixture containing fly ash resulted in a 3.4% reduction in the concrete emanation fraction, owing to the relatively low emanation that exists when fly ash is part of concrete. On average, the metakaolin constituents contained radium specific activities ranging from 67 Bq/kg to 600 Bq/kg and emanation fractions ranging from 8.4% to 15.5%, and changed the total concrete emanation fraction by roughly ± 5% relative to control samples. The results from this study suggest that SCMs can reduce indoor radon exposure from concrete, contingent upon SCM radionucleotide content and emanation fraction. Lastly, the experimental results provide SCM-specific concrete emanation fractions for indoor radon exposure modeling. - Highlights: • Fly ash or metakaolin SCMs can neutralize or reduce concrete emanation fractions. • The specific activity of constituents is a poor predictor of the concrete emanation fraction. • Exhalation from fly ash concretes represents a small fraction of the total indoor radon concentration

  15. CT measurements of SAP voids in concrete

    DEFF Research Database (Denmark)

    Laustsen, Sara; Bentz, Dale P.; Hasholt, Marianne Tange;

    2010-01-01

    X-ray computed tomography (CT) scanning is used to determine the SAP void distribution in hardened concrete. Three different approaches are used to analyse a binary data set created from CT measurement. One approach classifies a cluster of connected, empty voxels (volumetric pixel of a 3D image......) as one void, whereas the other two approaches are able to classify a cluster of connected, empty voxels as a number of individual voids. Superabsorbent polymers (SAP) have been used to incorporate air into concrete. An advantage of using SAP is that it enables control of the amount and size...

  16. LIGHTWEIGHT CONCRETE BASED GRANSHLAK

    Directory of Open Access Journals (Sweden)

    NETESA M. I.

    2016-02-01

    Full Text Available Raising of problem. Concrete advisable to obtain a low strength with local secondary resources for recycling and reduce the environmental burden on the environment. But it is important to design such concrete compositions with a reduced flow of cement. It is known that the coefficient of efficiency of use of cement in the concrete of the heavy and B10 is less than about 0.5, which is almost two times smaller than in class B15 concrete and above. Even lower coefficient of efficiency in light concrete cement low strength. Therefore, it is important to find patterns determining the composition of lightweight concrete based on local-products industry with more efficient use of cement in them. Purpose.. Based on the analysis of earlier research results, including with the use of methods of mathematical planning of experiments to determine the concrete contents, which can provide the requirements for the underlying layers of the floor, the compressive strength of which should correspond to the class B5. It is important to provide the required strength at minimum flow of the cement, which is the most expensive and energy-intensive part of concrete. Conclusion. Analysis of the test results of control samples of concrete in 28-day-old, the following laws. The required tensile strength of concrete compressive strength of 7.0 MPa can be obtained in the test range when used in formulations as a filler as the Dnieper hydroelectric power station fly ash and tailings Krivoy Rog iron ore YuGOK. To ensure providing the required characteristic strength of the concrete in the underlying layers of the floor is advisable to use a nominal composition per cubic meter of concrete: cement 160 kg granshlaka Plant named after Petrovsky, 675 kg of fly ash Dnieper HPP 390 kg, 400 kg of sand, 230 liters of water. Thus, while ensuring rational grain composition components can obtain the desired strength lightweight concrete based granshlaka plant Petrovsky, using as fillers

  17. Concrete fracture models and applications

    CERN Document Server

    Kumar, Shailendra

    2011-01-01

    Concrete-Fracture Models and Applications provides a basic introduction to nonlinear concrete fracture models. Readers will find a state-of-the-art review on various aspects of the material behavior and development of different concrete fracture models.

  18. KAJIAN EKSPERIMENTAL POROUS CONCRETE YANG MENGGUNAKAN SEMEN PORTLAND POZZOLAN DAN SERAT POLYPROPYENE

    OpenAIRE

    Irmawaty, Rita; Tjaronge, M. Wihardi

    2008-01-01

    ABSTRAK TEKNOSAINS 2009 Porous concrete adalah beton tanpa agregat halus dan hanya terdiri dari agregat kasar,semen dan air serta bahan kimia tambahan.Porositas atau lubang-lubang pada porous concrete bermanfaat untuk menyaring kotoran sehingga tidak terbawa ke dalam tanah atau saluran air.Selain itu,lubang-lubang tersebut diharapkan dapat menyerap energy sinar matahari.Porous concrete telah banyak digunakan sebagai lapisan permukaan jalan pada daerah pedestrian seperti tempat-tempat untuk...

  19. Gas entrainment rate coefficient of an ideal momentum atomizing liquid jet

    CERN Document Server

    Medrano, Fermín Franco; Velte, Clara Marika; Hodžić, Azur

    2016-01-01

    We propose a two-phase-fluid model for a turbulent full-cone high speed atomizing liquid jet that describes its dynamics in a simple but comprehensive manner with only the apex angle of the cone being a disposable parameter. The basic assumptions are that (i) the jet is statistically stationary and that (ii) it can be approximated by a mixture of a liquid and a gas with its phases in dynamic equilibrium. To derive the model, we impose conservation of the liquid volume and total momentum fluxes. Our model equation admits analytical solutions for the composite density and velocity of the two-phase fluid, both as functions of the distance from the nozzle, from which the dynamic pressure and gas the entrainment rate coefficient are calculated. Assuming a far-field approximation, we theoretically derive a constant gas entrainment rate coefficient solely in terms of the cone angle. Moreover, we carry out experiments for a single-phase turbulent air jet and show that the predictions of our model compare well with th...

  20. Airborne observation of mixing across the entrainment zone during PARADE 2011

    Science.gov (United States)

    Berkes, Florian; Hoor, Peter; Bozem, Heiko; Kunkel, Daniel; Sprenger, Michael; Henne, Stephan

    2016-05-01

    This study presents the analysis of the structure and air mass characteristics of the lower atmosphere during the field campaign PARADE (PArticles and RAdicals: Diel observations of the impact of urban and biogenic Emissions) on Mount Kleiner Feldberg in southwestern Germany during late summer 2011. We analysed measurements of meteorological variables (temperature, moisture, pressure, wind speed and direction) from radio soundings and of chemical tracers (carbon dioxide, ozone) from aircraft measurements. We focus on the thermodynamic and dynamic properties that control the chemical distribution of atmospheric constituents in the boundary layer. We show that the evolution of tracer profiles of CO2 and O3 indicate mixing across the inversion layer (or entrainment zone). This finding is supported by the analysis of tracer-tracer correlations which are indicative for mixing and the relation of tracer profiles in relation to the evolution of the boundary layer height deduced from radio soundings. The study shows the relevance of entrainment processes for the lower troposphere in general and specifically that the tracer-tracer correlation method can be used to identify mixing and irreversible exchange processes across the inversion layer.

  1. Assessment of ichthyoplankton entrainment at Pickering 'A' NGS using a pump/net in lake system

    International Nuclear Information System (INIS)

    Annual entrainment at Pickering 'A' NGS was estimated for alewife as 13.6 X 106 larvae and 409 X 106 eggs. A substantial portion of eggs and larvae entering the intake were dead due to natural mortality (41%-81%) prior to entrainment. Viable eggs and larvae, immediately following entrainment showed mortalities of 54% and 44% respectively. The latent mortality of entrained eggs was 100% (48 h)

  2. Environmental Impact of Concrete

    Directory of Open Access Journals (Sweden)

    Dan Babor

    2009-01-01

    Full Text Available The cement and concrete industries are huge. What does this mean in terms of the environment? Concrete and other cementitious materials have both environmental advantages and disadvantages. This paper takes a look at how these materials are made, then reviews a number of environmental considerations relating to their production and use.

  3. Concrete, hardened: Self desiccation

    DEFF Research Database (Denmark)

    Hansen, Ernst Jan De Place; Hansen, Kurt Kielsgaard; Persson, Bertil

    1999-01-01

    The test method covers the determination of internal relative humidity (RH) in hardened concrete and cement mortar using RH instruments. The determination of RH is done on crushed samples of concrete or cement motar. This test method is only for measuring equipment which gives off or takes up...

  4. Environmental Impact of Concrete

    OpenAIRE

    Dan Babor; Diana Plian; Loredana Judele

    2009-01-01

    The cement and concrete industries are huge. What does this mean in terms of the environment? Concrete and other cementitious materials have both environmental advantages and disadvantages. This paper takes a look at how these materials are made, then reviews a number of environmental considerations relating to their production and use.

  5. Concrete-Design

    Directory of Open Access Journals (Sweden)

    Leczovics Péter

    2014-12-01

    Full Text Available Present paper introduces a new interpretation of concrete, demonstrating some extreme possibilities of this rigid material such as a design element. In the first part a brief overview of the previous achievements are shown. The second part of this paper focuses on the relationship between concrete and fashion.

  6. concrete5 Beginner's Guide

    CERN Document Server

    Laubacher, Remo

    2011-01-01

    This book is part of Packt's Beginner's Guide series. You will be guided through the set up of a Concrete5 site with step-by-step practical examples. This book is ideal for developers who would like to build their first site with Concrete5. Some k

  7. Concrete quality assurance

    Energy Technology Data Exchange (ETDEWEB)

    Holz, N. [Harza Engineering Company, Chicago, IL (United States)

    2000-08-01

    This short article reports on progress at the world's largest civil construction project, namely China's Three Gorges hydro project. Work goes on around the clock to put in place nearly 28 M m{sup 3} of concrete. At every stage of the work there is strong emphasis on quality assurance (QA) and concrete is no exception. The US company Harza Engineering has been providing QA since the mid-1980s and concrete QA has been based on international standards. Harza personnel work in the field with supervisors developing educational tools for supervising concrete construction and quality, as well as providing training courses in concrete technology. Some details on flood control, capacity, water quality and environmental aspects are given..

  8. Estimated Entrainment of Dungeness Crab During Dredging For The Columbia River Channel Improvement Project

    Energy Technology Data Exchange (ETDEWEB)

    Pearson, Walter H.; Williams, Greg D.; Skalski, John R.

    2002-12-01

    The studies reported here focus on issues regarding the entrainment of Dungeness crab related to the proposed Columbia River Channel Improvement Project and provided direct measurements of crab entrainment rates at three locations (Desdomona Shoals, Upper Sands, and Miller Sands) from RM4 to RM24 during summer 2002. Entrainment rates for all age classes of crabs ranged from zero at Miller Sands to 0.224 crabs per cy at Desdemona Shoals in June 2002. The overall entrainment rate at Desdomona Shoals in September was 0.120 crabs per cy. A modified Dredge Impact Model (DIM) used the summer 2002 entrainment rates to project crab entrainment and adult equivalent loss and loss to the fishery for the Channel Improvement Project. To improve the projections, entrainment data from Flavel Bar is needed. The literature, analyses of salinity intrusion scenarios, and the summer 2002 site-specific data on entrainment and salinity all indicate that bottom salinity influences crab distribution and entrainment, especially at lower salinities. It is now clear from field measurements of entrainment rates and salinity during a period of low river flow (90-150 Kcfs) and high salinity intrusion that entrainment rates are zero where bottom salinity is less than 16 o/oo most of the time. Further, entrainment rates of 2+ and older crab fall with decreasing salinity in a clear and consistent manner. More elaboration of the crab distribution- salinity model, especially concerning salinity and the movements of 1+ crab, is needed.

  9. Bed-material entrainment and associated transportation infrastructure problems in streams of the Edwards Plateau, central Texas

    Science.gov (United States)

    Heitmuller, Franklin T.; Asquith, William H.

    2008-01-01

    The Texas Department of Transportation commonly builds and maintains low-water crossings (LWCs) over streams in the Edwards Plateau in Central Texas. LWCs are low-height structures, typically constructed of concrete and asphalt, that provide acceptable passage over seasonal rivers or streams with relatively low normal-depth flow. They are designed to accommodate flow by roadway overtopping during high-flow events. The streams of the Edwards Plateau are characterized by cobble- and gravel-sized bed material and highly variable flow regimes. Low base flows that occur most of the time occasionally are interrupted by severe floods. The floods entrain and transport substantial loads of bed material in the stream channels. As a result, LWCs over streams in the Edwards Plateau are bombarded and abraded by bed material during floods and periodically must be maintained or even replaced.

  10. Concrete sample point: 304 Concretion Facility

    Energy Technology Data Exchange (ETDEWEB)

    Rollison, M.D.

    1995-03-10

    This report contains information concerning the analysis of concretes for volatile organic compounds. Included are the raw data for these analysis and the quality control data, the standards data, and all of the accompanying chains-of-custody records and requests for special analysis.

  11. Thermal creep assisted dust lifting on Mars: Wind tunnel experiments for the entrainment threshold velocity

    CERN Document Server

    Küpper, Markus

    2015-01-01

    In this work we present laboratory measurements on the reduction of the threshold friction velocity necessary for lifting dust if the dust bed is illuminated. Insolation of a porous soil establishes a temperature gradient. At low ambient pressure this gradient leads to thermal creep gas flow within the soil. This flow leads to a sub-surface overpressure which supports lift imposed by wind. The wind tunnel was run with Mojave Mars Simulant and air at 3, 6 and 9 mbar, to cover most of the pressure range at martian surface levels. Our first measurements imply that the insolation of the martian surface can reduce the entrainment threshold velocity between 4 % and 19 % for the conditions sampled with our experiments. An insolation activated soil might therefore provide additional support for aeolian particle transport at low wind speeds.

  12. Thermal creep-assisted dust lifting on Mars: Wind tunnel experiments for the entrainment threshold velocity

    Science.gov (United States)

    Küpper, Markus; Wurm, Gerhard

    2015-07-01

    In this work we present laboratory measurements on the reduction of the threshold friction velocity necessary for lifting dust if the dust bed is illuminated. Insolation of a porous soil establishes a temperature gradient. At low ambient pressure this gradient leads to thermal creep gas flow within the soil. This flow leads to a subsurface overpressure which supports lift imposed by wind. The wind tunnel was run with Mojave Mars Simulant and air at 3, 6, and 9mbar, to cover most of the pressure range at Martian surface levels. Our first measurements imply that the insolation of the Martian surface can reduce the entrainment threshold velocity between 4% and 19% for the conditions sampled with our experiments. An insolation activated soil might therefore provide additional support for aeolian particle transport at low wind speeds.

  13. Performance of Waterless Concrete

    Science.gov (United States)

    Toutanji, Houssam; Evans, Steve; Grugel, Richard N.

    2010-01-01

    The development of permanent lunar bases is constrained by performance of construction materials and availability of in-situ resources. Concrete seems a suitable construction material for the lunar environment, but water, one of its major components, is an extremely scarce resource on the Moon. This study explores an alternative to hydraulic concrete by replacing the binding mix of concrete (cement and water) with sulfur. Sulfur is a volatile element on the lunar surface that can be extracted from lunar soils by heating. Sulfur concrete mixes were prepared to investigate the effect of extreme environmental conditions on the properties of sulfur concrete. A hypervelocity impact test was conducted, having as its target a 5-cm cubic sample of sulfur concrete. This item consisted of JSC-1 lunar regolith simulant (65%) and sulfur (35%). The sample was placed in the MSFC Impact Test Facility s Micro Light Gas Gun target chamber, and was struck by a 1-mm diameter (1.4e-03 g) aluminum projectile at 5.85 km/s. In addition, HZTERN code, provided by NASA was used to study the effectiveness of sulfur concrete when subjected to space radiation.

  14. Isospin dependence of entrainment in superfluid neutron stars in a relativistic model

    CERN Document Server

    Kheto, Apurba

    2014-01-01

    We study the entrainment effect between superfluid neutrons and charge neutral fluid (called the proton fluid) which is made of protons and electrons in neutron star interior in a relativistic model where baryon-baryon interaction is mediated by the exchange of $\\sigma$, $\\omega$ and $\\rho$ mesons. This model also includes scalar self interactions. The entrainment matrix and entrainment parameter are calculated using the parameter set of Glendenning (GL). The inclusion of $\\rho$ meson strongly influences the entrainment parameter ($\\epsilon_{mom}$) in a superfluid neutron star. It is constant at the core and drops to the surface. The entrainment parameter takes values within the physical range.

  15. Magnetized neutron stars with superconducting cores: effect of entrainment

    Science.gov (United States)

    Palapanidis, K.; Stergioulas, N.; Lander, S. K.

    2015-09-01

    We construct equilibrium configurations of magnetized, two-fluid neutron stars using an iterative numerical method. Working in Newtonian framework we assume that the neutron star has two regions: the core, which is modelled as a two-component fluid consisting of type-II superconducting protons and superfluid neutrons, and the crust, a region composed of normal matter. Taking a new step towards more complete equilibrium models, we include the effect of entrainment, which implies that a magnetic force acts on neutrons, too. We consider purely poloidal field cases and present improvements to an earlier numerical scheme for solving equilibrium equations, by introducing new convergence criteria. We find that entrainment results in qualitative differences in the structure of field lines along the magnetic axis.

  16. Numerical Modeling of Deep Mantle Flow: Thermochemical Convection and Entrainment

    Science.gov (United States)

    Mulyukova, Elvira; Steinberger, Bernhard; Dabrowski, Marcin; Sobolev, Stephan

    2013-04-01

    One of the most robust results from tomographic studies is the existence of two antipodally located Large Low Shear Velocity Provinces (LLSVPs) at the base of the mantle, which appear to be chemically denser than the ambient mantle. Results from reconstruction studies (Torsvik et al., 2006) infer that the LLSVPs are stable, long-lived, and are sampled by deep mantle plumes that rise predominantly from their margins. The origin of the dense material is debated, but generally falls within three categories: (i) a primitive layer that formed during magma ocean crystallization, (ii) accumulation of a dense eclogitic component from the recycled oceanic crust, and (iii) outer core material leaking into the lower mantle. A dense layer underlying a less dense ambient mantle is gravitationally stable. However, the flow due to thermal density variations, i.e. hot rising plumes and cold downwelling slabs, may deform the layer into piles with higher topography. Further deformation may lead to entrainment of the dense layer, its mixing with the ambient material, and even complete homogenisation with the rest of the mantle. The amount of the anomalous LLSVP-material that gets entrained into the rising plumes poses a constraint on the survival time of the LLSVPs, as well as on the plume buoyancy, on the lithospheric uplift associated with plume interaction and geochemical signature of the erupted lavas observed at the Earth's surface. Recent estimates for the plume responsible for the formation of the Siberian Flood Basalts give about 15% of entrained dense recycled oceanic crust, which made the hot mantle plume almost neutrally buoyant (Sobolev et al., 2011). In this numerical study we investigate the mechanics of entrainment of a dense basal layer by convective mantle flow. We observe that the types of flow that promote entrainment of the dense layer are (i) upwelling of the dense layer when it gets heated enough to overcome its stabilizing chemical density anomaly, (ii

  17. An entrainment model for the turbulent jet in a coflow

    Science.gov (United States)

    Enjalbert, Nicolas; Galley, David; Pierrot, Laurent

    2009-09-01

    The entrainment hypothesis was introduced by G.I. Taylor to describe one-dimensionally the development of turbulent jets issuing into a stagnant or coflowing environment. It relates the mass flow rate of surrounding fluid entrained into the jet to the characteristic velocity difference between the jet and the coflow. A model based on this hypothesis along with axial velocity assumed to follow a realistic Gaussian distribution is presented. It possesses an implicit analytical solution, and its results are compared and shown to be fully equivalent to previously published models that are rather based on a spreading hypothesis. All of them are found to be in agreement with experimental results, on a wide range of downstream positions and for various coflow intensities. To cite this article: N. Enjalbert et al., C. R. Mecanique 337 (2009).

  18. Mixing and entrainment in hydraulically driven stratified sill flows

    DEFF Research Database (Denmark)

    Nielsen, Morten Holtegaard; Pratt, Larry; Helfrich, Karl

    2004-01-01

    -interface entrainment velocity is compared with numerical simulations based on a model with continuously varying stratification and velocity. The locations of critical flow (hydraulic control) in the continuous model are estimated by observing the direction of propagation of small-amplitude long-wave disturbances...... introduced into the flow field. Although some of the trends predicted by the shallow-water model are observed in the continuous model, the agreement between the interface profiles and the position of critical flow is quantitatively poor. A reformulation of the equations governing the continuous flow suggests...... that the reduced gravity model systematically underestimates inertia and overestimates buoyancy. These differences are quantified by shape coefficients that measure the vertical non-uniformities of the density and horizontal velocity that arise, in part, by incomplete mixing of entrained mass and momentum over...

  19. Axially symmetric equations for differential pulsar rotation with superfluid entrainment

    CERN Document Server

    Antonelli, Marco

    2016-01-01

    We propose an analytical two-components model for pulsar rotational dynamics: the aim is to reduce the 3D hydrodynamical problem to a 1D (radial) problem, using the hypothesis of negligible azimuthal inhomogeneities. The result is the construction of a computationally simple model that takes into account for the non-uniform structure of the star, entrainment effect and differential rotation of the superfluid component. For the first time all these ingredients are treated in a fully consistent way within the picture provided by our initial hypotheses. Our treatment clarifies which are the physical inputs needed to build, to current knowledge, more realistic simulations of rotating neutron stars and gives a neat description of the effect of entrainment when straight vortex lines are considered. Moreover, on this basis, we briefly introduce a new method that can be used to put a constraint to the mass of the pulsars that display very large glitches and to the relative spin up timescales.

  20. Updrafts, Downdrafts, Entrainment, and Detrainment in the Giga-LES

    Science.gov (United States)

    Krueger, S. K.; Glenn, I.

    2012-12-01

    We are investigating the properties of evolving three-dimensional updraft and downdraft "cores" in a model dataset from the Giga-LES, a large-domain LES (large-eddy simulation) of tropical oceanic deep convection (Khairoutdinov et al. 2009). We have also applied the analysis method developed by Kuang and Bretherton (2006) to investigate various aspects of the ensemble characteristics of cumulus convection in the Giga-LES. Our results agree with those of Kuang and Bretherton for the cumulus updraft properties. We have examined the relative merits of different entrainment and cloud-top-height assumptions in spectral plume models of cumulus updrafts, the characteristics of downdrafts, and the nature of a rapid transition from shallow to deep convection.isualization of cumulus clouds from the Giga-LES. The realistic structure is associated with entrainment.

  1. concrete5 cookbook

    CERN Document Server

    Strack, David

    2013-01-01

    The Cookbook-style recipes allow you to go both directly to your topic of interest or follow topics throughout a chapter to gain in-depth knowledge. This practical Cookbook will cater to the needs of both intermediate and advanced concrete5 developers.This book is geared towards intermediate to advanced PHP developers who would like to learn more about the concrete5 content management system. Developers already familiar with concrete5 will learn new time-saving tricks and will find the book to be a great reference tool.

  2. Properties of high-workability concrete with recycled concrete aggregate

    OpenAIRE

    Safiuddin; Ubagaram Johnson Alengaram; Abdus Salam; Mohd Zamin Jumaat; Fahrol Fadhli Jaafar; Hawa Binti Saad

    2011-01-01

    This study presents the effects of recycled concrete aggregate (RCA) on the key fresh and hardened properties of concrete. RCA was used to produce high-workability concrete substituting 0-100% natural coarse aggregate (NCA) by weight. The slump and slump flow of fresh concretes were determined to ensure high workability. In addition, the compressive, flexural and splitting tensile strengths, modulus of elasticity, and permeable voids of hardened concretes were determined. The test results rev...

  3. Design of ultra-lightweight concrete: towards monolithic concrete structures

    OpenAIRE

    Yu Qing Liang; Spiesz Przemek; Brouwers Jos

    2013-01-01

    This study addresses the development of ultra-lightweight concrete. A moderate strength and an excellent thermal conductivity of the lightweight concrete are set as the design targets. The designed lightweight aggregates concrete is targeted to be used in monolithic concrete façade structure, performing as both load bearing element and thermal insulator. The developed lightweight concrete shows excellent thermal properties, with a low thermal conductivity of about 0.12 W/(m·K); and moderate m...

  4. Entrained Flow Reactor Test of Potassium Capture by Kaolin

    DEFF Research Database (Denmark)

    Wang, Guoliang; Jensen, Peter Arendt; Wu, Hao;

    2015-01-01

    In the present study a method to simulate the reaction between gaseous KCl and kaolin at suspension fired condition was developed using a pilot-scale entrained flow reactor (EFR). Kaolin was injected into the EFR for primary test of this method. By adding kaolin, KCl can effectively be captured......-bed reactor. The method using the EFR developed in this study will be applied for further systematic investigation of different additives....

  5. Experimental research of liquid entrainment through ADS-4 in AP1000

    International Nuclear Information System (INIS)

    Highlights: • We performed experimental research of liquid entrainment through ADS-4 in AP1000. • Effect of various factors on entrainment at T-junction was conducted. • Visualization research was conducted to make entrainment mechanism clear. - Abstract: In this study, based on a T-junction that consists of Automatic Depressurization System Stage Four (ADS-4) and hot leg in an AP1000 plant, a small-scale experimental research on entrainment at a T-junction was performed. This study mainly focused on the effect of various factors on entrainment, such as the effect of branch size, branch shape and liquid crossflow. The flow pattern map was plotted from the experimental data, and the visualization research indicated that the entrainment phenomena through a large size branch were apparently different from that through a small branch. Three entrainment phenomena were observed in the studies, two entrainment mechanisms could be found in the stratified flow regime entrainment area, the existence of branch contributed to generating intermittent flow in the horizontal main pipe, and the backflow region was observable in the vicinity of a large size branch inlet. Also, experimental research showed that downstream of the branch of T-junction had an important effect on the onset entrainment, and liquid crossflow did not seem to affect the onset entrainment

  6. State of art an Overview on the Tensile Strength and Flexural Strength of Concrete in different Curing Methods

    Directory of Open Access Journals (Sweden)

    J. Allen Paul Edson

    2014-11-01

    Full Text Available The concrete is made of different ingredients such as cement, fine aggregate, and coarse aggregate but it is a homogeneous material when it is in a harden concrete. The strength of concrete decides the life span of any concrete structure. The factors which affect the strength of concrete are the type of material used, size of aggregate, water cement ratio, improper compaction and improper curing. Curing is one of the major factors in the failure of concrete. Curing is defined as the process of promoting the hydration of cement. The grade used in the manufacture of concrete may be M20, M30 grade. This paper deals with the overview on the tensile strength and flexural strength of concrete when the concrete is exposed to various curing methods such as Water curing (Ponding and Immersion, Air Curing (Dry air curing, and plastic film curing at 3 days, 7 days, 28 days and 56 days. It is studied that the tensile and flexural strength of concrete during immersion method is high when compared with Air curing and plastic film curing. It is found that the water curing is the most effective method of curing with the maximum of 10% increase in tensile strength and 15% increase in flexural strength of concrete when compared with other curing methods. On comparison with self compacting concrete (SCC and Normal cement concrete (NCC under different curing methods the tensile strength and flexural strength of SCC is high than NCC.

  7. Entrainment of coarse grains using a discrete particle model

    International Nuclear Information System (INIS)

    Conventional bedload transport models and incipient motion theories relying on a time-averaged boundary shear stress are incapable of accounting for the effects of fluctuating near-bed velocity in turbulent flow and are therefore prone to significant errors. Impulse, the product of an instantaneous force magnitude and its duration, has been recently proposed as an appropriate criterion for quantifying the effects of flow turbulence in removing coarse grains from the bed surface. Here, a discrete particle model (DPM) is used to examine the effects of impulse, representing a single idealized turbulent event, on particle entrainment. The results are classified according to the degree of grain movement into the following categories: motion prior to entrainment, initial dislodgement, and energetic displacement. The results indicate that in all three cases the degree of particle motion depends on both the force magnitude and the duration of its application and suggest that the effects of turbulence must be adequately accounted for in order to develop a more accurate method of determining incipient motion. DPM is capable of simulating the dynamics of grain entrainment and is an appropriate tool for further study of the fundamental mechanisms of sediment transport

  8. Constant darkness restores entrainment to phase-delayed Siberian hamsters.

    Science.gov (United States)

    Ruby, Norman F; Joshi, Nirav; Heller, H Craig

    2002-12-01

    Over 90% of Siberian hamsters (Phodopus sungorus) fail to reentrain to a 5-h phase delay of a 16:8-h photocycle. Because constant darkness (DD) restores rhythms disrupted by constant light, we tested whether DD could also restore entrainment. DD began 0, 5, or 14 days after a 5-h phase delay, and the light-dark cycle was reinstated 14 days later. All hamsters exposed to DD on day 0 reentrained, whereas 42% reentrained irrespective of whether DD began 5 or 14 days later. For these latter two groups, tau (tau) and alpha (alpha) in DD predicted reentrainment; animals that reentrained had a mean tau and alpha of 24.1 and 8.9 h, respectively, whereas those that failed to reentrain maintained a mean tau and alpha of 25.0 and of 7.1 h, respectively. Restoration of entrainment by DD is somewhat paradoxical because it suggests that reentrainment to the photocycle was prevented by continued exposure to that same photocycle. The dichotomy of circadian responses to DD suggests "entrainment" phenotypes that are similar to those of photoperiodic responders and nonresponders.

  9. Neural entrainment to the rhythmic structure of music.

    Science.gov (United States)

    Tierney, Adam; Kraus, Nina

    2015-02-01

    The neural resonance theory of musical meter explains musical beat tracking as the result of entrainment of neural oscillations to the beat frequency and its higher harmonics. This theory has gained empirical support from experiments using simple, abstract stimuli. However, to date there has been no empirical evidence for a role of neural entrainment in the perception of the beat of ecologically valid music. Here we presented participants with a single pop song with a superimposed bassoon sound. This stimulus was either lined up with the beat of the music or shifted away from the beat by 25% of the average interbeat interval. Both conditions elicited a neural response at the beat frequency. However, although the on-the-beat condition elicited a clear response at the first harmonic of the beat, this frequency was absent in the neural response to the off-the-beat condition. These results support a role for neural entrainment in tracking the metrical structure of real music and show that neural meter tracking can be disrupted by the presentation of contradictory rhythmic cues.

  10. Entrainment of respiratory frequency to exercise rhythm during hypoxia.

    Science.gov (United States)

    Paterson, D J; Wood, G A; Marshall, R N; Morton, A R; Harrison, A B

    1987-05-01

    Breathing frequency (f) is often reported as having an integer-multiple relationship to limb movement (entrainment) during rhythmic exercise. To investigate the strength of this coupling while running under hypoxic conditions, two male Caucasians and four male Nepalese porters were tested in the Annapurna region of the Himalayas at altitudes of 915, 2,135, 3,200, 4,420, and 5,030 m. In an additional study in a laboratory at sea level, three male and four female subjects inspired various O2-N2 mixtures [fraction of inspired O2 (FIO2) = 20.93, 17.39, 14.40, 11.81%] that were administered in a single-blind randomized fashion during a treadmill run (40% FIO2 maximum O2 consumption). Breathing and gait signals were stored on FM tape and later processed on a PDP 11/73 computer. The subharmonic relationships between these signals were determined from Fourier analysis (power spectrum), and the coincidence of coupling occurrence was statistically modeled. Entrainment decreased linearly during increasing hypoxia (P less than 0.01). Moreover, a significant linear increase in f occurred during hypoxia (P less than 0.05), whereas stride frequency and metabolic rate remained constant, suggesting that hypoxic-induced increases in f decreased the degree of entrainment. PMID:3597249

  11. Stratocumulus Precipitation and Entrainment Experiment (SPEE) Field Campaign Report

    Energy Technology Data Exchange (ETDEWEB)

    Albrecht, Bruce [Univ. of Miami, Miami, FL (United States); Ghate, Virendra [Argonne National Lab. (ANL), Argonne, IL (United States); CADeddu, Maria [Argonne National Lab. (ANL), Argonne, IL (United States)

    2016-06-01

    The scientific focus of this project was to examine precipitation and entrainment processes in marine stratocumulus clouds. The entrainment studies focused on characterizing cloud turbulence at cloud top using Doppler cloud radar observations. The precipitation studies focused on characterizing the precipitation and the macroscopic properties (cloud thickness, and liquid water path) of the clouds. This project will contribute to the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility’s overall objective of providing the remote-sensing observations needed to improve the representation of key cloud processes in climate models. It will be of direct relevance to the components of ARM dealing with entrainment and precipitation processes in stratiform clouds. Further, the radar observing techniques that will be used in this study were developed using ARM Southern Great Plains (SGP) facility observations under Atmospheric System Research (ASR) support. The observing systems operating automatously from a site located just north of the Center for Interdisciplinary Remotely-Piloted Aircraft Studies (CIRPAS) aircraft hangar in Marina, California during the period of 1 May to 4 November 2015 included: 1. Microwave radiometer: ARM Microwave Radiometer, 3-Channel (MWR3C) with channels centered at 23.834, 30, and 89 GHz; supported by Dr. Maria Cadeddu. 2. Cloud Radar: CIRPAS 95 GHz Frequency Modulated Continuous Wave (FMCW) Cloud Radar (Centroid Frequency Chirp Rate [CFCR]); operations overseen by Drs. Ghate and Albrecht. 3. Ceilometer: Vaisala CK-14; operations overseen by Drs. Ghate and Albrecht.

  12. Application of Orthogonal Experiment in Compound Admixture of Freezing Mine Shaft Lining Concrete%正交法在冻结井壁砼复合外加剂试验中的应用

    Institute of Scientific and Technical Information of China (English)

    宗翔; 徐颖; 李寅珺

    2012-01-01

    In order to achieve the setting and hardening of mine shaft lining concrete under the minus temperature in freezing construction and to meet the demands of every performance of concrete, the technique of compounding air entraining admixture and antifreezing admixture and early strength water reducing admixture was applied in this research. Based on the Orthogonal experimental design, several mix proportions of compound admixture for early strength liquid mine shaft lining concrete were developed in the laboratory. The data collected in this research provide reference for the optimum mix proportion of the adulteration quantity of the concrete admixture. The results show that the 2. 1% amount of compound antifreezing admixture achieves favorable effects of liquid,early strength,freezing prevention and antifreezing.%为了使冻结施工井壁混凝土能够在负温条件下凝结与硬化,并满足其各项性能要求,采用引气剂+防冻剂+早强减水剂复合的技术路线,通过正交试验设计复配了适应冻结施工早强流态井壁混凝土的复合外加剂.通过试验分析最终确定各组分掺量之间的最佳配比.复合外加剂的掺量为2.1%,可起到流态、早强、防冻及抗冻的作用.

  13. 汉阳河特大桥自密实微膨胀混凝土的制备及其施工工艺%Preparation and Construction Technology of Self-compacting Expansive Concrete for Hanyang River Bridge

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    This paper prepared the C50 self compacting and micro expansional concrete by using P·O 42.5 cement, high-performance expansive agent,local raw aggregate and adding fly ash II,silica fume mineral admixtures.It was suc-cessfully applied into the construction of Hanyang River steel tube arch bridge in Wufeng County,Yichang City.The engineering application showed that:the concrete with proposed construction mixture proportion met the standard and construct requirements;the appropriate amount of expansive agent compensated the shrinkage degree of concrete;the viscosity and fluidity of the concrete was significantly improved by adding tackifier constituents and air entraining com-ponents in admixture.The construction was carried out successfully with lift pumping construction technology.%以Ⅱ级粉煤灰和硅灰作为矿物掺和料,利用当地砂石原材料、P·O 42.5水泥和 HCSA 高性能膨胀剂,制备出了 C50自密实补偿收缩混凝土,并应用于宜昌五峰汉阳河特大桥钢管拱桥中。工程应用表明:制备出的混凝土满足标准和施工要求,适当掺量的膨胀剂可以补偿混凝土收缩,外加剂中增粘组分及引气组分可明显提升混凝土的黏聚性和流动性,通过采用泵送顶升现场施工工艺成功对宜昌五峰汉阳河特大桥进行了施工。

  14. Corrosion-resistant sulfur concretes

    Science.gov (United States)

    McBee, W. C.; Sullivan, T. A.; Jong, B. W.

    1983-04-01

    Sulfur concretes have been developed by the Bureau of Mines as construction materials with physical and mechanical properties that suit them for use in acid and salt corrosive environments where conventional concretes fail. Mixture design methods were established for preparing sulfur concretes using different types of aggregates and recently developed mixed-modified sulfur cements. Bench-scale testing of the sulfur concretes has shown their potential value. Corrosion resistance, strength, and durability of sulfur concrete are superior to those of conventional materials. Field in situ evaluation tests of the sulfur concretes as replacement for conventional concrete materials are in progress in corrosive areas of 24 commercial chemical, fertilizer, and metallurgical plants.

  15. A historical examination of concrete

    International Nuclear Information System (INIS)

    The requirement that concrete in radioactive waste repositories be stable physically and chemically for very long times has initiated studies of ancient and old concretes. This report is a contribution to this effort. After a description of the history of cement and concrete, the published literature relating to the analysis of old and ancient concrete is reviewed. A series of samples spanning the history of concrete has been obtained; a variety of physical and chemical techniques have been employed to characterize these samples. Reasons for survival of ancient concretes, and for durability of early, reinforced concretes are identified. Recommendations for further studies are given. 132 refs

  16. Precast concrete pavements

    Science.gov (United States)

    Rollings, R. S.; Chou, Y. T.

    1981-11-01

    This report reviewed published literature on precast concrete pavements and found that precast concrete pavements have had some limited application in airfields, roads, and storage areas. This review of past experience and an analytical study of precast slabs concluded that existing design and construction techniques can be adapted for use with precast concrete pavements, but more work is needed to develop effective and easily constructed load transfer designs for slab joints. Precast concrete does not offer any advantage for conventional pavements due to its high cost and surface roughness, but it may find applications for special problems such as construction in adverse weather, subgrade settlement, temporary pavements that need to be relocated, and military operations.

  17. Strengthening lightweight concrete

    Science.gov (United States)

    Auskern, A.

    1972-01-01

    Polymer absorption by lightweight concretes to improve bonding between cement and aggregate and to increase strength of cement is discussed. Compressive strength of treated cement is compared with strength of untreated product. Process for producing polymers is described.

  18. Stone-hard concrete

    NARCIS (Netherlands)

    Wassink, J.

    2014-01-01

    A polymer prepared from waste water extends the useful life of concrete. It also appears to be suitable as a protective coating for offshore applications. Chemistry professor Stephen Picken predicts that this ‘alginate’ could become huge.

  19. Detailed characterization of current North American portland cements and clinkers and the implications for the durability of modern concrete

    Science.gov (United States)

    Arjunan, P.

    -day curing period. In the present study, a modified Stark method was used to evaluate the expansion produced by SEF/DEF. Analyses of SEF/DEF mortar data showed that the total length change was negatively correlated to SO3 and positively correlated to CaO contents of cement. The present study showed that there does not appear to be an SEF/DEF expansion problem if (1) the cement contains low SO3 (less than 3.5), SO3/Al2O3 ratio less than 0.7, and SO 3/CaO ratio less than 0.06, and (2) the concrete is air-entrained and the temperature does not exceed 60°C.

  20. High performance polymer concrete

    OpenAIRE

    Frías, M.; San-José, J. T.

    2007-01-01

    This paper studies the performance of concrete whose chief components are natural aggregate and an organic binder —a thermosetting polyester resin— denominated polymer concrete or PC. The material was examined macro- and microscopically and its basic physical and mechanical properties were determined using mercury porosimetry, scanning electron microscopy (SEM-EDAX), X-ray diffraction (XRD) and strength tests (modulus of elasticity, stress-strain curves and ultimate strengths). A...

  1. Performance of "Waterless Concrete"

    Science.gov (United States)

    Toutanji, H. A.; Grugel, R. N.

    2009-01-01

    Waterless concrete consists of molten elementary sulfur and aggregate. The aggregates in a lunar environment will be lunar rocks and soil. Sulfur is present on the Moon in Troilite soil (FeS) and, by oxidation of the soil, iron and sulfur can be produced. Sulfur concrete specimens were cycled between liquid nitrogen (approx.]91 C) and room temperature (^21 C) to simulate exposure to a lunar environment. Cycled and control specimens were subsequently tested in compression at room temperatures (^21 C) and ^-101 C. Test results showed that due to temperature cycling, the compressive strength of cycled specimens was 20% of those non-cycled. This reduction in strength can be attributed to the large differences in thermal coefficients of expansion of the materials constituting the concrete which promoted cracking. Similar sulfur concrete mixtures were strengthened with short and long glass fibres. The lunar regolith simulant was melted in a 25 cc Pt- Rh crucible in a Sybron Thermoline high temperature MoSi2 furnace at melting temperatures of 1450 to 1600 C for times of 30 min to i hour. Glass fibres and small rods were pulled from the melt. The glass fibres were used to reinforce sulfur concrete plated to improve the flexural strength of the sulfur concrete. Beams strengthened with glass fibres showed to exhibit an increase in the flexural strength by as much as 45%.

  2. Fracture Mechanics of Concrete

    DEFF Research Database (Denmark)

    Ulfkjær, Jens Peder

    Chapter 1 Chapter l contains the introduction to this thesis. The scope of the thesis is partly to investigate different numerical and analytical models based on fracture mechanical ideas, which are able to predict size effects, and partly to perform an experimental investigation on high-strength......Chapter 1 Chapter l contains the introduction to this thesis. The scope of the thesis is partly to investigate different numerical and analytical models based on fracture mechanical ideas, which are able to predict size effects, and partly to perform an experimental investigation on high......-strength concrete. Chapter 2 A description of the factors which influence the strength and cracking of concrete and high strength concrete is made. Then basic linear fracture mechanics is outlined followed by a description and evaluation of the models used to describe concrete fracture in tension. The chapter ends...... and the goveming equations are explicit and simple. These properties of the model make it a very powerful tool, which is applicable for the designing engineer. The method is also extended to reinforced concrete, where the results look very promising. The large experimental investigation on high-strength concrete...

  3. Nanomodified magnesian schungite protective concrete

    Directory of Open Access Journals (Sweden)

    A.S. Ryzhov

    2010-03-01

    Full Text Available Currently, there is increasing demand for building materials with low permeability to the radioactive gas radon and materials that have protective properties against radiation exposure and non-ionizing radiation. Formulations have been developed and now special building flooring and plaster radiation protective mixtures are commercially available. With the acceleration the pace of development of nuclear energy safe utilization of liquid and solid radioactive waste is a vital task for the survival of humanity.With the use of innovative magnesian barite and magnesian schungite composites opportunities to solidify LRW and solid radioactive waste monolithing are expanded. Magnesium-schungite nanostructured concrete exceed heavy concrete on Portland cement by gamma radiation and strength characteristics reducing multiplicity. Formulations are protected by a patent for an invention.The paper shows a clear advantage of magnesia cement (compared with Portland cement in terms of specific mass energy parameters Em and Wm. The data demonstrates that the magnesia cement is characterized by higher parameters of maximum frequency of oscillation of the atoms ?m, which, apparently, is the key to explaining the increased protection (shielding properties of materials based on magnesia cement mixed with shungite of gamma radiation and exposure to radiofrequency electromagnetic radiation the range.Magnesium-schungite radiation-shielding materials are approved by Rospotrebnadzor for use for collective protection to reduce the income of radon in indoor air, gamma and x-ray production, residential, public and administrative buildings, as well as in food, pharmaceutical, medical and child care.

  4. Recycled Concrete as Aggregate for Structural Concrete Production

    Directory of Open Access Journals (Sweden)

    Mirjana Malešev

    2010-04-01

    Full Text Available A comparative analysis of the experimental results of the properties of fresh and hardened concrete with different replacement ratios of natural with recycled coarse aggregate is presented in the paper. Recycled aggregate was made by crushing the waste concrete of laboratory test cubes and precast concrete columns. Three types of concrete mixtures were tested: concrete made entirely with natural aggregate (NAC as a control concrete and two types of concrete made with natural fine and recycled coarse aggregate (50% and 100% replacement of coarse recycled aggregate. Ninety-nine specimens were made for the testing of the basic properties of hardened concrete. Load testing of reinforced concrete beams made of the investigated concrete types is also presented in the paper. Regardless of the replacement ratio, recycled aggregate concrete (RAC had a satisfactory performance, which did not differ significantly from the performance of control concrete in this experimental research. However, for this to be fulfilled, it is necessary to use quality recycled concrete coarse aggregate and to follow the specific rules for design and production of this new concrete type.

  5. Carbonation of concrete incorporating high volumes of fly ash[ACI SP-234-19

    Energy Technology Data Exchange (ETDEWEB)

    Bouzoubaa, N.; Tamtsia, B.; Chevrier, R.L.; Bilodeau, A.; Malhotra, V.M. [Natural Resources Canada, Ottawa, ON (Canada). CANMET International Centre for Sustainable Development of Cement and Concrete; Zhang, M.H. [National Univ. of Singapore (Singapore). Dept. of Civil Engineering

    2006-07-01

    Carbonation of concrete involves the chemical interaction of atmospheric carbon dioxide (CO{sub 2}) and calcium hydroxide (Ca(OH){sub 2}) liberated during cement hydration. In high-volume fly ash (HVFA) concrete, the amount of calcium hydroxide and the binding of carbon dioxide will be greatly reduced due to its lower portland cement content and the pozzolanic-reaction. Therefore, the carbonation resistance of the HVFA concrete is reduced. This study investigated 3 HVFA concrete mixtures incorporating 58 per cent of fly ash, each made with a different fly ash. The mixtures also incorporated 2 control portland cement concrete mixtures, one with a water to cementitious materials ratio of 0.32 and the other with a 28-day compressive strength equivalent to that of the HVFA concrete. Before the accelerated carbonation test, the concrete was subjected to 3 different curing modes. The compressive strength of the hardened concrete was summarized along with the slump, unit weight and air content of the fresh concrete. The study showed that the effect of fly ash on the carbonation resistance of concrete is mainly due to the reactivity of fly ash and its effect on the microstructure of the hardened cement paste in the concrete. A concrete composed of low reactivity fly ash will develop a microstructure that becomes denser with a longer moist curing period. Therefore, the penetration of CO{sub 2} into the concrete will be slower. For both the HVFA and the control portland cement concrete, the carbonation depth of the concrete was found to decrease with an increase in the duration of moisture curing from 7 to 28 days. It was concluded that carbonation is not an issue for well-cured HVFA concrete because of the low water-cementitious materials ratio, the dense structure and low permeability of the concrete. 19 refs., 6 tabs., 11 figs.

  6. Doing Duo – a Case Study of Entrainment in William Forsythe’s Choreography Duo

    Directory of Open Access Journals (Sweden)

    Elizabeth eWaterhouse

    2014-10-01

    Full Text Available Entrainment theory focuses on processes in which interacting (i.e. coupled rhythmic systems stabilize, producing synchronization in the ideal sense, and forms of phase related rhythmic coordination in complex cases. In human action, entrainment involves spatiotemporal and social aspects, characterizing the meaningful activities of music, dance, and communication. How can the phenomenon of human entrainment be meaningfully studied in complex situations such as dance? We present an in-progress case study of entrainment in William Forsythe's choreography Duo, a duet in which coordinated rhythmic activity is achieved without an external musical beat and without touch-based interaction. Using concepts of entrainment from different disciplines as well as insight from Duo performer Riley Watts, we question definitions of entrainment in the context of dance. The functions of chorusing, turn-taking, complementary action, cues and alignments are discussed and linked to supporting annotated video material. While Duo challenges the definition of entrainment in dance as coordinated response to an external musical or rhythmic signal, it supports the definition of entrainment as coordinated interplay of motion and sound production by active agents (i.e., dancers in the field. Agreeing that human entrainment should be studied on multiple levels, we suggest that entrainment between the dancers in Duo is elastic in time and a propose how to test this hypothesis empirically. We do not claim that our proposed model of elasticity is applicable to all forms of human entrainment nor to all to examples of entrainment in dance. Rather, we suggest studying higher order phase correction (the stabilizing tendency of entrainment as a potential aspect to be incorporated into other models.

  7. Doing Duo - a case study of entrainment in William Forsythe's choreography "Duo".

    Science.gov (United States)

    Waterhouse, Elizabeth; Watts, Riley; Bläsing, Bettina E

    2014-01-01

    Entrainment theory focuses on processes in which interacting (i.e., coupled) rhythmic systems stabilize, producing synchronization in the ideal sense, and forms of phase related rhythmic coordination in complex cases. In human action, entrainment involves spatiotemporal and social aspects, characterizing the meaningful activities of music, dance, and communication. How can the phenomenon of human entrainment be meaningfully studied in complex situations such as dance? We present an in-progress case study of entrainment in William Forsythe's choreography Duo, a duet in which coordinated rhythmic activity is achieved without an external musical beat and without touch-based interaction. Using concepts of entrainment from different disciplines as well as insight from Duo performer Riley Watts, we question definitions of entrainment in the context of dance. The functions of chorusing, turn-taking, complementary action, cues, and alignments are discussed and linked to supporting annotated video material. While Duo challenges the definition of entrainment in dance as coordinated response to an external musical or rhythmic signal, it supports the definition of entrainment as coordinated interplay of motion and sound production by active agents (i.e., dancers) in the field. Agreeing that human entrainment should be studied on multiple levels, we suggest that entrainment between the dancers in Duo is elastic in time and propose how to test this hypothesis empirically. We do not claim that our proposed model of elasticity is applicable to all forms of human entrainment nor to all examples of entrainment in dance. Rather, we suggest studying higher order phase correction (the stabilizing tendency of entrainment) as a potential aspect to be incorporated into other models. PMID:25374522

  8. Basic properties of recycled concrete by orthogonal test%正交法分析再生混凝土基本力学性能

    Institute of Scientific and Technical Information of China (English)

    陈爱玖; 孙晓培; 杨粉; 孙嘉伟

    2013-01-01

    用正交分析法分析矿渣粉、粉煤灰、引气剂、聚丙烯纤维和再生粗骨料5个因素对再生混凝土抗压和劈拉强度的影响,得出再生混凝土的最佳配合比.试验表明:粉煤灰和矿渣粉是影响再生混凝土力学性能的主要因素;随着粉煤灰掺量增加,再生混凝土28 d抗压强度和劈拉强度分别降低2.6%~8.8%和0.6%~4.7%,粉煤灰掺量30%的再生混凝土90d抗压强度比28 d提高了49%;再生混凝土的强度随着矿渣粉掺量的增加呈增大趋势,抗压强度增幅为4.9%~8.1%,劈拉强度增幅为0.4%~4.6%.%This paper researched the effect of mufti-factor (slag powder, fly ash, air-entraining agent, polypropylene fiber, and recycled coarse aggregate) on the compressive strength and splitting strength recycled concrete by the way of orthogonal test method,and the optimum mixture ratio of recycled concrete is determined by the same way. The results show that: the fly ash and the slag powder were the most important factors for the mechanical properties of concrete. The compressive strength and splitting strength of recycled concrete in 28 d decreases 2.6%~8.8% and 0.6%~4.7% by the rate of fly ash increasing, the 90 d strength im proved 49% obviously compared with 28 d when the ratio of fly ash was 30%. The compressive strength and splitting strength of recycled concrete increased 4.9%~8.1% and 0.4%~4.6% respectively by the rate of slag powder increasing.

  9. An experimental investigation of flow patterns and liquid entrainment in a horizontal-tube evaporator

    Science.gov (United States)

    Barnhart, John Steven

    An experimental study of two-phase flow patterns and droplet entrainment in a horizontal-tube evaporator was conducted. Measurements were made with serpentine aluminum and glass evaporators with geometries typical of those used for domestic refrigeration. The refrigerant in the majority of tests was R134a, which will replace R12 for refrigeration and automotive air-conditioning in 1995. The phenomenon of primary interest was the nonequilibrium transport of droplets within superheated vapor at the evaporator exit. Of particular concern were substantial variations in the liquid rate with time, and corresponding fluctuations in exit temperature. These variations are due to the formation of slugs which rapidly transport a surplus of liquid toward the exit. A flow loop was constructed to circulate oil-free refrigerant through the evaporator under widely varying conditions. Liquid carry over (expressed as a dimensionless entrained mass fraction, EMF) was measured as a function of inlet quality, heat flux, mass flux, and exit superheat. A laser-based phase/Doppler particle analyzer was used to measure droplet diameters and velocities at the evaporator exit. Tests with three refrigerants over wide ranges of operating conditions revealed time-averaged EMF's of no more than 0.1 percent. Analysis of variance showed exit superheat to have the strongest effect, followed by mass flux, inlet quality, and heat flux. Time-averaged EMF's varied with operating conditions by several orders of magnitude, decreasing with increasing superheat level (due to lower entrainment rates near the exit and more rapid droplet vaporization) and mass flux and inlet quality (due to reduced slug formation). The incidence of slug flow and its effect on evaporator exit conditions were documented in time-resolved experiments, using techniques such as auto- and cross-correlation and Fourier transform. Time-resolved EMF's as high as one percent were observed, as well as sharp reductions in exit superheat

  10. Magnesium oxychloride cement concrete

    Indian Academy of Sciences (India)

    A K Misra; Renu Mathur

    2007-06-01

    The scope of magnesium oxychloride (MOC) cement in concrete works has been evaluated. MOC cement concrete compositions of varying strengths having good placing and finishing characteristics were prepared and investigated for their compressive and flexural strengths, -values, abrasion resistance etc. The durability of MOC concrete compositions against extreme environmental conditions viz. heating–cooling, freezing–thawing, wetting–drying and penetration and deposition of salts etc were investigated. The results reveal that MOC concrete has high compressive strength associated with high flexural strength and the ratio of compressive to flexural strength varies between 6 and 8. The elastic moduli of the compositions studied are found to be 23–85 GPa and the abrasion losses between 0.11 and 0.20%. While alternate heating–cooling cycles have no adverse effect on MOC concrete, it can be made durable against freezing–thawing and the excessive exposure to water and salt attack by replacing 10% magnesium chloride solution by magnesium sulphate solution of the same concentration.

  11. Studies of historic concrete

    International Nuclear Information System (INIS)

    Underground concrete repositories for nuclear waste will have to maintain their integrity for hundreds of years. This study examines ancient concretes and assesses the suitability of equivalent modern materials for underground storage. Thirty four ancient samples have been obtained from Great Britain, Austria and Italy. One 19th century sample was also collected. The samples were examined using a variety of analytical techniques (including scanning electron microscopy, optical microscopy, chemical analysis and pH determination). The samples were also subjected to a range of physical tests. Most of the samples examined were very weak and porous although they had retained full structural integrity. With the exception of the 19th century sample, none of the concretes had maintained pH alkaline enough to immobilize radionuclides. Hydrated calcium silicates have been detected in some samples which are similar to those observed in modern Portland cement concretes. These stable cementitious species have endured for almost two thousand years. All the ancient concretes and mortars examined contained natural pozzolanic material or crushed burnt clay. This may have had some effect on the reduction in alkalinity although the main reason was full carbonation of calcium hydroxide

  12. The effects of chronic marijuana use on circadian entrainment.

    Science.gov (United States)

    Whitehurst, Lauren N; Fogler, Kethera; Hall, Kate; Hartmann, Matthew; Dyche, Jeff

    2015-05-01

    Animal literature suggests a connection between marijuana use and altered circadian rhythms. However, the effect has not yet been demonstrated in humans. The present study examined the effect of chronic marijuana use on human circadian function. Participants consisted of current users who reported smoking marijuana daily for at least a year and non-marijuana user controls. Participants took a neurocognitive assessment, wore actigraphs and maintained sleep diaries for three weeks. While no significant cognitive changes were found between groups, data revealed that chronic marijuana use may act as an additional zeitgeber and lead to increased entrainment in human users.

  13. Entrained Flow Reactor Test of Potassium Capture by Kaolin

    OpenAIRE

    Wang, Guoliang; Jensen, Peter Arendt; Hao WU; Bøjer, Martin; Jappe Frandsen, Flemming; Glarborg, Peter

    2015-01-01

    In the present study a method to simulate the reaction between gaseous KCl and kaolin at suspension fired condition was developed using a pilot-scale entrained flow reactor (EFR). Kaolin was injected into the EFR for primary test of this method. By adding kaolin, KCl can effectively be captured, forming water-insoluble K-aluminosilicate. The amount of K captured by 1 g kaolin rose when increasing the molar ratio of K/Si in the reactant. Changing of reaction temperature from 1100 °C to 1300 °C...

  14. Measured gas and particle temperatures in VTT's entrained flow reactor

    DEFF Research Database (Denmark)

    Clausen, Sønnik; Sørensen, L.H.

    2006-01-01

    Particle and gas temperature measurements were carried out in experiments on VTTs entrained flow reactor with 5% and 10% oxygen using Fourier transform infrared emission spectroscopy (FTIR). Particle temperature measurements were performed on polish coal,bark, wood, straw particles, and bark...... and wood particles treated with additive. A two-color technique with subtraction of the background light was used to estimate particle temperatures during experiments. A transmission-emission technique was used tomeasure the gas temperature in the reactor tube. Gas temperature measurements were in good...

  15. Increasing exfiltration from pervious concrete and temperature monitoring.

    Science.gov (United States)

    Tyner, J S; Wright, W C; Dobbs, P A

    2009-06-01

    Pervious concrete typically has an infiltration rate far exceeding any expectation of precipitation rate. The limiting factor of a retention based pervious concrete system is often defined by how quickly the underlying soil subgrade will infiltrate the water temporarily stored within the concrete and/or aggregate base. This issue is of particular importance when placing a pervious concrete system on compacted fine textured soils. This research describes the exfiltration from twelve pervious concrete plots constructed on a compacted clay soil in eastern Tennessee, USA. Several types of treatments were applied to the clay soil prior to placement of the stone aggregate base and pervious concrete in an attempt to increase the exfiltration rate, including: 1) control--no treatment; 2) trenched--soil trenched and backfilled with stone aggregate; 3) ripped--soil ripped with a subsoiler; and 4) boreholes--placement of shallow boreholes backfilled with sand. The average exfiltration rates were 0.8 cm d(-1) (control), 4.6 cm d(-1) (borehole), 10.0 cm d(-1) (ripped), and 25.8 cm d(-1) (trenched). The trenched treatment exfiltrated fastest, followed by the ripped and then the borehole treatments, although the ripped and borehole treatments were not different from one another at the 5% level of significance. The internal temperature of the pervious concrete and aggregate base was monitored throughout the winter of 2006-2007. Although the temperature of the pervious concrete dropped below freezing 24 times, freezing concrete temperatures never coincided with free water being present in the large pervious concrete pores. The coldest recorded air temperature was -9.9 degrees C, and the corresponding coldest recorded pervious concrete temperature was -7.1 degrees C. The temperature of the pervious concrete lagged diurnal air temperature changes and was generally buffered in amplitude, particularly when free water was present since the addition of water increases the thermal

  16. Water entrainment in intercompartmental flows resulting from pipeline breaks: literature study. Topical report

    International Nuclear Information System (INIS)

    The extensive engineering literature on two-phase flow in ducts, nozzles and orifices is reviewed with respect to intercompartmental flows in nuclear reactor safety applications. The topics of flow patterns, holdup or slip, two-phase critical flow and entrainment are reviewed and discussed. The entrainment fraction of droplets in the vapor phase of an annular flow pattern can be estimated in the case of vertical or horizontal steady duct flow at positions well downstream from the duct entrance. No general correlation for the prediction of entrainment is available, however. In addition the literature pertaining to nuclear containment calculation methods, experiments, calculation surveys and verifications is surveyed. The containment analysis methods are quite comprehensive and well-developed. Currently no models for estimating entrainment in containment problems are being used, but entrainment has been treated as an arbitrary parameter and some attention has been given to entrainment in the interpretation of experiments

  17. A Heart for Interaction: Physiological Entrainment and Behavioral Coordination in a Collective, Creative Construction Task

    CERN Document Server

    Fusaroli, Riccardo; Roepstoff, Andreas; Tylén, Kristian

    2015-01-01

    Interpersonal physiological entrainment is increasingly argued to underlie rapport, empathy and even team performance. Inspired by the model of interpersonal synergy, we investigate the presence, temporal development, possible mechanisms and impact of interpersonal heart rate entrainment during individual and collective creative LEGO construction tasks. In Study 1 we show how HR entrainment is driven by a plurality of sources including task constraints and behavioral coordination. Generally, HR entrainment is more prevalent in individual trials (involving participants doing the same things) than in collective ones (involving participants taking turns and performing complementary actions). However, when contrasted against virtual pairs, collective trials display more stable HR entrainment supporting the idea that online social interaction plays a role. Furthermore, HR entrainment is found to grow across collective but not individual trials. In Study 2 we further show that in collective trials the dynamics of H...

  18. Mechanical properties of refractory concretes for boilers; Propriedades mecanicas de concretos refratarios para caldeiras

    Energy Technology Data Exchange (ETDEWEB)

    Angioletto, E.; Pelisser, F.; Peterson, M.; Angioletto, E.; Rocha, M.R.; Arnt, A.B.C. [Universidade do Estado de Santa Catarina (UDESC), Criciuma, SC (Brazil)], E-mail: ean@unesc.net; Coelho, R. [Tractebel Energia, Florianpolis, SC (Brazil)

    2010-07-01

    Refractory concretes are used in extremely physically demanding conditions. An important example is concretes used as sealing systems in boilers, where their dimensional stability at high temperatures is fundamental to durability and has a strong impact on maintenance costs and system idleness. In this work, refractory concretes with different compositions were characterized and then tested by dilatometry, for compressive strength and in assays involving adherence between tensile concrete/metal inserts, simulating the fixing system in boilers. Analysis of the results showed that refractory concretes do not present retraction due to air during drying, eliminating the possibility of cracking. While casting the plate/prototype with metal inserts, satisfactory concrete/metal adherence was verified and surface cracking occurred that did not influence the tensile bond strength between the insert and the concrete. (author)

  19. HIGH TEMPERATURE PERFORMANCE OF SUSTAINABLE CONCRETE WITH RECYCLED CONCRETE AGGREGATES

    OpenAIRE

    Gales, John; Parker, Thomas; Green, Mark F.; Cree, Duncan; Bisby, Luke

    2014-01-01

    The substitution of conventional aggregates in concrete with recycled concrete aggregates (RCA) can act to lower environmental impact. Applications of concrete with RCA are limited because of a lack of research providing clear design guidance. Specifically, the performance in fire must be considered. To address this need, three different concrete mixes were assessed for performance at high temperature with the only variable being the proportion of coarse aggregate substituted with RCA. For ea...

  20. Bridge concrete deteriorating diagnosis by infrared thermography

    Science.gov (United States)

    Shibata, Hiroki; Fukuyama, Nobuhiro; Sakuma, Joji; Mochizuki, Jun; Kimura, Yukinori

    2006-04-01

    Bridge is indispensable as social overhead capital. In the past, concrete construction was believed to be semi-permanent. Actually, however, concrete is deteriorated by various factors including seawater damage, annual temperature change, etc. Therefore, it is now obvious that maintenance and management are essential to keep performance of the bridge. In Japan, we had many reports of using infrared thermography for diagnosis of building, mainly for delamination of tile and mortar used for surface of the building for more than 10 years. In recent years, infrared thermogrephy is more actively used for delamination of surface of the bridge. Passive method is usually used for open-air concrete structure diagnosis, which utilizes intraday environmental temperature change and/or radiation energy emitted from the sun which create delta-T of delamination portion of the concrete structure. It is very important to take thermal image at right conditions. Otherwise, you may easily fall onto false diagnosis. In our presentation, many case examples and study of thermal data will be shown, which are taken at the right condition.

  1. In time with the music : the concept of entrainment and its significance for ethnomusicology.

    OpenAIRE

    Clayton, Martin; Sager, Rebecca; Will, Udo

    2005-01-01

    Entrainment, broadly defined, is a phenomenon in which two or more independent rhythmic processes synchronize with each other. To illuminate the significance of entrainment for various directions of music research and promote a nuanced understanding of the concept among ethnomusicologists, this publication opens with an exposition of entrainment research in various disciplines, from physics to linguistics and psychology, while systematically introducing basic concepts that are directly releva...

  2. Separation of Erucic Acid from Rape-Seed Oil Using Supercritical Carbon Dioxide with Entrainer

    Institute of Scientific and Technical Information of China (English)

    云志; 钱仁渊; 等

    2002-01-01

    Separation of erucic acid from rape-seed oil using supercritical carbon dioxide with entrainer was carried on a pilot column with an inner diameter 14 mm and an effective total height 2.2m.Experiments were focused on the effects of entrainers.i.e.acetone.ethanol and ethyl acetate,on the extraction.It is showed that entrainers made selectivity lower,but separation time shorter.

  3. Impact of entrainment and impingement on fish populations in the Hudson River estuary. Volume I. Entrainment-impact estimates for six fish populations inhabiting the Hudson River estuary

    Energy Technology Data Exchange (ETDEWEB)

    Boreman, J.; Barnthouse, L.W.; Vaughn, D.S.; Goodyear, C.P.; Christensen, S.W.; Kumar, K.D.; Kirk, B.L.; Van Winkle, W.

    1982-01-01

    This volume is concerned with the estimation of the direct (or annual) entrainment impact of power plants on populations of striped bass, white perch, Alosa spp. (blueback herring and alewife), American shad, Atlantic tomcod, and bay anchovy in the Hudson River estuary. Entrainment impact results from the killing of fish eggs, larvae, and young juveniles that are contained in the cooling water cycled through a power plant. An Empirical Transport Model (ETM) is presented as the means of estimating a conditional entrainment mortality rate (defined as the fraction of a year class which would be killed due to entrainment in the absence of any other source of mortality). Most of this volume is concerned with the estimation of several parameters required by the ETM: physical input parameters (e.g., power-plant withdrawal flow rates); the longitudinal distribution of ichthyoplankton in time and space; the duration of susceptibility of the vulnerable organisms; the W-factors, which express the ratios of densities of organisms in power plant intakes to densities of organisms in the river; and the entrainment mortality factors (f-factors), which express the probability that an organism will be killed if it is entrained. Once these values are obtained, the ETM is used to estimate entrainment impact for both historical and projected conditions.

  4. Impact of entrainment and impingement on fish populations in the Hudson River estuary. Volume I. Entrainment-impact estimates for six fish populations inhabiting the Hudson River estuary

    International Nuclear Information System (INIS)

    This volume is concerned with the estimation of the direct (or annual) entrainment impact of power plants on populations of striped bass, white perch, Alosa spp. (blueback herring and alewife), American shad, Atlantic tomcod, and bay anchovy in the Hudson River estuary. Entrainment impact results from the killing of fish eggs, larvae, and young juveniles that are contained in the cooling water cycled through a power plant. An Empirical Transport Model (ETM) is presented as the means of estimating a conditional entrainment mortality rate (defined as the fraction of a year class which would be killed due to entrainment in the absence of any other source of mortality). Most of this volume is concerned with the estimation of several parameters required by the ETM: physical input parameters (e.g., power-plant withdrawal flow rates); the longitudinal distribution of ichthyoplankton in time and space; the duration of susceptibility of the vulnerable organisms; the W-factors, which express the ratios of densities of organisms in power plant intakes to densities of organisms in the river; and the entrainment mortality factors (f-factors), which express the probability that an organism will be killed if it is entrained. Once these values are obtained, the ETM is used to estimate entrainment impact for both historical and projected conditions

  5. Performance of Bridge Decks and Girders with Lightweight Aggregate Concrete, v. 2 of 2

    OpenAIRE

    Ramirez, J.A.; Olek, J.; Rolle, Eric Joseph; Malone, Brian Joseph

    2000-01-01

    Structural lightweight concrete is a very versatile material and Haydite and Minergy lightweight aggregates can be utilized in the mixture development of concrete for use in girders and decks in bridges. More widespread use of lightweight aggregates (LWA) would result in savings in construction cost due to considerable dead load reduction. The materials phase of this research study evaluated the fresh concrete properties (slump, unit weight, and air content), the mechanical properties of ...

  6. INVESTIGATION ON MECHANICAL PROPERTIES OF STRUCTURAL LIGHTWEIGHT CONCRETE MADE WITH PUMICE AGGREGATE

    OpenAIRE

    Selçuk TÜRKEL; Bimen KADİROĞLU

    2007-01-01

    In this study, structural lightweight concrete mixtures are produced by using Kayseri pumice aggregate. The other constituent materials used in producing the lightweight concrete mixtures are; CEM I 42.5 cement as binder, silica fume and fly ash as mineral admixtures. The following properties are determined; slump, unit weight and air content of fresh mix, as well as unit weight, compressive strength, splitting tensile strength and flexural strength of hardened concrete. Test results show tha...

  7. Mechanical Properties of Concrete with Marine Sand as Partial Replacement of Fine Aggregate

    OpenAIRE

    Dr. V.Ravindra,; Anil Kumar Buraka

    2016-01-01

    The process of depleting sources of natural aggregates challenges the production of technically and environmentally adequate concrete. Alternative material from marine sources is good enough for the replacement of fine aggregate in the concrete. The material was stockpiled in the open air and no washing, drying or decontamination process was carried out. Physical and chemical properties of DMS material were determined. All the materials used in the concrete were selected and teste...

  8. Electrokinetic decontamination of concrete

    Energy Technology Data Exchange (ETDEWEB)

    Lomasney, H. [ISOTRON Corp., New Orleans, LA (United States)

    1995-10-01

    The U.S. Department of Energy has assigned a priority to the advancement of technology for decontaminating concrete surfaces which have become contaminated with radionuclides, heavy metals, and toxic organics. This agency is responsible for decontamination and decommissioning of thousands of buildings. Electrokinetic extraction is one of the several innovative technologies which emerged in response to this initiative. This technique utilizes an electropotential gradient and the subsequent electrical transport mechanism to cause the controlled movement of ionics species, whereby the contaminants exit the recesses deep within the concrete. This report discusses the technology and use at the Oak Ridge k-25 plant.

  9. Ancient concrete works

    CERN Document Server

    Sparavigna, Amelia Carolina

    2011-01-01

    It is commonly believed that the ancient Romans were the first to create and use concrete. This is not true, as we can easily learn from the Latin literature itself. For sure, Romans were able to prepare high-quality hydraulic cements, comparable with the modern Portland cements. In this paper, we will see that the use of concrete is quite older, ranging back to the Homeric times. For instance, it was used for the floors of some courts and galleries of the Mycenaean palace at Tiryns

  10. Concentrated loads on concrete

    DEFF Research Database (Denmark)

    Lorenzen, Karen Grøndahl; Nielsen, Mogens Peter

    1997-01-01

    This report deals with concentrated loads on concrete.A new upper bound solution in the axisymmetrical case of a point load in the center of the end face of a cylinder is developed.Based on previous work dealing with failure mechanisms and upper bound solutions, new approximate formulas are devel......This report deals with concentrated loads on concrete.A new upper bound solution in the axisymmetrical case of a point load in the center of the end face of a cylinder is developed.Based on previous work dealing with failure mechanisms and upper bound solutions, new approximate formulas...

  11. Experimental studies on spray and gas entrainment characteristics of biodiesel fuel: Implications of gas entrained and fuel oxygen content on soot formation

    International Nuclear Information System (INIS)

    Experiments were performed inside the constant volume vessel to simulate the real diesel engine conditions. The LIF–PIV (Laser Induced Florescence – Particulate Image Velocimetry) technique was used to characterize the spray and gas entrainment characteristics of the fuels while the OH-chemiluminescence and two color pyrometry were applied to obtain information about the combustion processes. Biodiesel from palm oil (BDF (Biodiesel Fuel)) and the JIS #2 diesel fuel were utilized. It was observed that the SMD (Sauter mean diameter) obtained through an empirical equation decreased by increasing the injection pressure from 100 to 300 MPa and reducing the nozzle diameter from 0.16 to 0.08 mm. BDF has higher SMD values compared to diesel thus signifying inferior atomization. By increasing the injection pressure up to 300 MPa and reducing the nozzle diameter to 0.08 mm, the normal velocity and total mass flow rate of the entrained gas by the fuels increased. Due to higher viscosity and density properties, BDF possessed inferior atomization characteristics which made the normal velocity and total mass flow rate of the entrained gas lower compared to diesel. Due to inferior atomization which led to less gas being entrained upstream of the lift-off flame, the fuel oxygen content in BDF played a significant role in soot formation processes. - Highlights: • Spray and gas entrainment characteristics of biodiesel (BDF (Biodiesel Fuel)) and fuel were investigated. • Effect of injector parameters on BDF spray and gas entrainment characteristics was identified. • Higher viscosity and density of BDF yielded inferior spray atomization processes. • Gas entrainment velocity and mass flow rate of gas entrained by BDF lower. • Gas entrained had less effect on BDF's soot formation

  12. Identified proprioceptive afferents and motor rhythm entrainment in the crayfish walking system.

    Science.gov (United States)

    Elson, R C; Sillar, K T; Bush, B M

    1992-03-01

    1. In crayfish, Pacifastacus leniusculus, remotion of a walking leg stretches the thoraco-coxal (TC) muscle receptor organ (TCMRO), located at the leg's articulation with the thorax. In vitro, alternate stretch and release of the fourth leg's TCMRO entrained the centrally generated rhythmic motor output to that leg, with the remotor phase of the rhythm entraining to TCMRO stretch, the promoter phase to release. This coordination of motor bursts to afferent input corresponds to that of active, rhythmic movements in vivo. 2. Entrainment was rapid in onset (stable coordination resulting within the first or second stimulus cycle) and was relatively phase-constant (whatever the stimulus frequency, during 1:1 entrainment, remotor bursts began near the onset of stretch and promotor bursts began near the onset of release). Outside the range of 1:1 entrainment, 2:1, 1:2, and 1:3 coordination ratios (rhythm:stimulus) were encountered. Resetting by phasic stimulation of the TCMRO was complete and probabilistic: effective stimuli triggered rapid transitions between the two burst phases. 3. The TCMRO is innervated by two afferents, the nonspiking S and T fibers, which generate graded depolarizing receptor potentials in response to stretch. During proprioceptive entrainment, the more phasic T fiber depolarized and hyperpolarized more rapidly or in advance of the more tonic S fiber. These receptor potentials were modified differently in the two afferents by interaction with central synaptic inputs that were phase-locked to the entrained motor rhythm. 4. Injecting slow sinusoidal current into either afferent alone could entrain motor rhythms: promoter phase bursts were entrained to depolarization of the S fiber or hyperpolarization of the T fiber, whereas the converse response was obtained for remotor phase bursts. 5. During proprioceptive entrainment, tonic hyperpolarization of the S fiber weakened entrained promotor bursts and allowed remotor burst durations to increase

  13. Debris entrainment and landform genesis during tidewater glacier surges

    Science.gov (United States)

    Lovell, Harold; Fleming, Edward J.; Benn, Douglas I.; Hubbard, Bryn; Lukas, Sven; Rea, Brice R.; Noormets, Riko; Flink, Anne E.

    2015-08-01

    The englacial entrainment of basal debris during surges presents an opportunity to investigate processes acting at the glacier bed. The subsequent melt-out of debris-rich englacial structures during the quiescent phase produces geometrical ridge networks on glacier forelands that are diagnostic of surge activity. We investigate the link between debris entrainment and proglacial geomorphology by analyzing basal ice, englacial structures, and ridge networks exposed at the margins of Tunabreen, a tidewater surge-type glacier in Svalbard. The basal ice facies display clear evidence for brittle and ductile tectonic deformation, resulting in overall thickening of the basal ice sequence. The formation of debris-poor dispersed facies ice is the result of strain-induced metamorphism of meteoric ice near the bed. Debris-rich englacial structures display a variety of characteristics and morphologies and are interpreted to represent the incorporation and elevation of subglacial till via the squeezing of till into basal crevasses and hydrofracture exploitation of thrust faults, reoriented crevasse squeezes, and preexisting fractures. These structures are observed to melt-out and form embryonic geometrical ridge networks at the base of a terrestrially grounded ice cliff. Ridge networks are also located at the terrestrial margins of Tunabreen, neighboring Von Postbreen, and in a submarine position within Tempelfjorden. Analysis of network characteristics allows these ridges to be linked to different formational mechanisms of their parent debris-rich englacial structures. This in turn provides an insight into variations in the dominant tectonic stress regimes acting across the glacier during surges.

  14. Establishing Communication between Neuronal Populations through Competitive Entrainment.

    Science.gov (United States)

    Wildie, Mark; Shanahan, Murray

    2011-01-01

    The role of gamma frequency oscillation in neuronal interaction, and the relationship between oscillation and information transfer between neurons, has been the focus of much recent research. While the biological mechanisms responsible for gamma oscillation and the properties of resulting networks are well studied, the dynamics of changing phase coherence between oscillating neuronal populations are not well understood. To this end we develop a computational model of competitive selection between multiple stimuli, where the selection and transfer of population-encoded information arises from competition between converging stimuli to entrain a target population of neurons. Oscillation is generated by Pyramidal-Interneuronal Network Gamma through the action of recurrent synaptic connections between a locally connected network of excitatory and inhibitory neurons. Competition between stimuli is driven by differences in coherence of oscillation, while transmission of a single selected stimulus is enabled between generating and receiving neurons via Communication-through-Coherence. We explore the effect of varying synaptic parameters on the competitive transmission of stimuli over different neuron models, and identify a continuous region within the parameter space of the recurrent synaptic loop where inhibition-induced oscillation results in entrainment of target neurons. Within this optimal region we find that competition between stimuli of equal coherence results in model output that alternates between representation of the stimuli, in a manner strongly resembling well-known biological phenomena resulting from competitive stimulus selection such as binocular rivalry. PMID:22275892

  15. Establishing communication between neuronal populations through competitive entrainment

    Directory of Open Access Journals (Sweden)

    Mark eWildie

    2012-01-01

    Full Text Available The role of gamma frequency oscillation in neuronal interaction, and the relationship between oscillation and information transfer between neurons, has been the focus of much recent research. While the biological mechanisms responsible for gamma oscillation and the properties of resulting networks are well studied, the dynamics of changing phase relationships and mechanisms underlying the formation of phase coherence between oscillating neuronal populations are not well understood. To this end we develop a computational model of competitive selection between multiple stimuli, where selection and the transfer of population-encoded information arises from competition between converging stimuli to entrain a target population of neurons. Oscillation is generated by Pyramidal-Interneuronal Network Gamma through the action of recurrent synaptic connections between a locally connected network of excitatory and inhibitory neurons. Competition between stimuli is driven by differences in coherence of oscillation, while transmission of a single selected stimulus is enabled between generating and receiving neurons via Communication-through-Coherence. We explore the effect of varying synaptic parameters on the competitive transmission of stimuli over different neuron models, and identify a continuous region within the parameter space of the recurrent synaptic loop where inhibition-induced oscillation results in entrainment of target neurons. Within this optimal region we find that competition between stimuli of equal coherence results in model output that alternates between representation of the stimuli, in a manner strongly resembling well-known biological phenomena resulting from competitive stimulus selection such as binocular rivalry.

  16. Predicting Method of Concrete Service Life Based on Damage Development Equation%基于损伤演化方程的混凝土寿命预测方法

    Institute of Scientific and Technical Information of China (English)

    余红发; 孙伟; 麻海燕; 张云升; 缪昌文; 金祖权; 刘建忠

    2012-01-01

    Based on the damage development equation of concrete subjected to freezing-thawing cycles or chemical attacks, a systematic theory and the basic operation for the prediction on service life of concrete structure were presented. Validity of the damage development equation of concrete was established by the vast data obtained through single factor. Service life prediction of some national key projections, such as the potassic manure plant in salt lake of Qinghai and Beijing Cloverleaf Bridge, were studied by specially designed durability experiments, which included single factor (salt lake bittern attack), double factor (wet-dry cycles compound with salt lake bittern attack), 3. 5% mass concentration NaCl solution salt-frost experiments. Results show that either ordinary Portland cement concrete or high strength concrete is not applicable to the potassic manure plant in salt lake of Qinghai. Service life of Beijing Cloverleaf Bridge can also meet the requirements of 50 years since C60 air-entrained high performance concrete subjected to salt-frost action are adopted.%基于混凝土的冻融或腐蚀损伤演化方程,提出了一套预测混凝土结构使用寿命的基本方法与理论体系;用单一冻融因素作用下的大量试验数据验证了混凝土的损伤演化方程;通过专门设计的盐湖卤水腐蚀单一因素和(干湿循环+盐湖卤水腐蚀)双重因素、3.5%质量浓度的NaCl盐冻试验,研究了青海盐湖钾肥和北京城市立交桥主体结构混凝土的使用寿命预测问题.结果表明:青海盐湖钾肥工程不宜采用普通混凝土和高强混凝土;C60引气高性能混凝土在盐冻作用下满足北京城市立交桥50年的使用要求.

  17. Recycled aggregate concrete; an overview

    OpenAIRE

    Sorato, Renan

    2016-01-01

    The aim of this Bachelor’s thesis was to investigate whether recycled materials can be incorporated into the production of concrete without compromising the compressive strength of the concrete produced. In order to shed light on the compressive strength of concrete made from recycled materials, the thesis reviewed studies in which waste materials are utilised as recycled aggregates in the composition of concrete and presented the results of this synthesis and analysis. It was found that som...

  18. TEXTILE TECHNOLOGIES IN CONCRETE ENVIRONMENTS."

    OpenAIRE

    Morrow, Ruth; Belford, Patricia

    2007-01-01

    Girli Concrete is a cross disciplinary funded research project based in the University of Ulster involving a textile designer/ researcher, an architect/ academic and a concrete manufacturing firm.Girli Concrete brings together concrete and textile technologies, testing ideas ofconcrete as textile and textile as structure. It challenges the perception of textiles as only the ‘dressing’ to structure and instead integrates textile technologies into the products of building products. Girli Concre...

  19. Structural lightweight concrete: recent research

    OpenAIRE

    Walraven, J.; Den Uijl, J.; Stroband, J.; AI-ZubiN.; Gijsbers, J.; Naaktgeboren, M.

    1995-01-01

    As a result of a number of reasons new interest developed into the use of lightweight aggregate concrete. Within the scope of this development, a modernized code for lightweight concrete had to be written. In order to support this development, a number of research projects have been carried out. The aim of the research was to verify the appropriateness of a number of design methods for lightweight concrete. The behaviour of various types of lightweight concrete has been studied.

  20. Noise emission of concrete pavement surfaces produced by diamond grinding

    Directory of Open Access Journals (Sweden)

    Jens Skarabis

    2015-04-01

    Full Text Available In Germany, diamond grinding is frequently used to improve the evenness and skid resistance of concrete pavement surfaces. Since diamond grinding has been observed to affect tyre/pavement noise emission favourably, the relationship among surface texture, concrete composition and noise emission of concrete pavement surfaces has been systematically investigated. The simulation program SPERoN was used in a parameter study to investigate the main factors which affect noise emission. Based on the results of the simulations, textured concrete surfaces were produced by using a laboratory grinding machine. As well as the composition of the concrete, the thickness and spacing of the diamond blades were varied. The ability of the textured surfaces to reduce noise emission was assessed from the texture characteristics and air flow resistance of textured surfaces measured in the laboratory. It was found that concrete composition and, in particular, the spacing of the blades affected the reduction in noise emission considerably. The noise emission behaviour of numerous road sections was also considered in field investigations. The pavement surfaces had been textured by diamond grinding during the last years or decades. The results show that diamond grinding is able to provide good, durable noise-reducing properties. Several new pavement sections were investigated using thicknesses and spacings of the blades similar to those used in the laboratory to optimize noise emission reduction. It is concluded that diamond grinding is a good alternative to exposed aggregate concrete for the production of low-noise pavement surfaces.

  1. SEQUENTIAL RADIOCHEMICAL ANALYSIS FOR RUTHENIUM, STRONTIUM AND CESIUM IN ENVIRONMENTAL AIR

    Science.gov (United States)

    In routine surveillance operations, the radionuclide measurement of air discharged from an operating nuclear facility involves the entrainment of radionuclides on selective filter or absorptive media, and the determination of their gross beta activity. However, a more sensitive t...

  2. Thin Concrete Barrel Vault

    NARCIS (Netherlands)

    Kamerling, M.W.

    2013-01-01

    The paper presents the structural design of a thin barrel vault constructed with Fusée Ceramique infill elements. The load transfer is analyzed and validated. For the structure composed of Fusée Ceramique elements, steel and concrete the stresses are calculated and compared to the stresses given in

  3. Danish High Performance Concretes

    DEFF Research Database (Denmark)

    Nielsen, M. P.; Christoffersen, J.; Frederiksen, J.

    1994-01-01

    In this paper the main results obtained in the research program High Performance Concretes in the 90's are presented. This program was financed by the Danish government and was carried out in cooperation between The Technical University of Denmark, several private companies, and Aalborg University...

  4. Designing concrete for durability

    Directory of Open Access Journals (Sweden)

    Boyd, A. J.

    2001-12-01

    Full Text Available Some of the factors affecting the durability of modern concrete structures are discussed, with an emphasis on the problems caused by modern portland cements. This is followed by a description of some concrete durability issues of current interest, such as plastic shrinkage, seawater attack, and sulfate attack. The strategies for testing for durability are also discussed. It is concluded that, to produce durable concretes, a holistic approach to concrete construction must be adopted.

    Se discuten algunos de los factores que influyen en la durabilidad de las estructuras de hormigón modernas, haciendo énfasis en los problemas causados por el cemento Portland. A esto sigue una descripción de algunas cuestiones de interés general de la durabilidad del hormigón tales como la retracción plástica, el ataque por agua de mar y el ataque por sulfatos. Se discuten también las estrategias de los ensayos de durabilidad. Se concluye que para producir hormigones durables se debe adoptar un enfoque holístico de la construcción con hormigón.

  5. Hydrophobic treatment of concrete

    NARCIS (Netherlands)

    Vries, J.de; Polder, R.B.

    1997-01-01

    As part of the maintenance policy of the dutch Ministry of Transport, Civil Engineering Division, hydrophobic treatment of concrete was considered as an additional protective measure against penetration of aggressive substances, for instance deicing salts in bridge decks. A set of tests was designed

  6. Hydrophobic treatment of concrete

    NARCIS (Netherlands)

    Vries, J. de; Polder, R.B.

    1996-01-01

    As part of the maintenance policy of the Dutch Ministry of Transport, Civil Engineering Division, hydrophobic treatment of concrete was considered as an additional protective measure against penetration of aggressive substances, for instance deicing salts in bridge decks. A set of tests was designed

  7. Contaminated soil concrete blocks

    NARCIS (Netherlands)

    Korte, de A.C.J.; Brouwers, H.J.H.; Limbachiya, Mukesh C.; Kew, Hsein Y.

    2009-01-01

    According to Dutch law the contaminated soil needs to be remediated or immobilised. The main focus in this article is the design of concrete blocks, containing contaminated soil, that are suitable for large production, financial feasible and meets all technical and environmental requirements. In ord

  8. Teaching concrete structures

    DEFF Research Database (Denmark)

    Goltermann, Per

    2014-01-01

    The teaching of concrete structures has been revised and a number of new approaches have been developed, implemented and evaluated. Inductive teaching, E-learning and “patches” have been found to be improvements and may be an inspiration and help for others development of the teaching and learning...

  9. 空分装置中冷箱基础珠光砂混凝土冬季施工%Perlite concrete winter construction of cold case foundation in air separation facility

    Institute of Scientific and Technical Information of China (English)

    袁江城

    2012-01-01

    结合具体工程实例及珠光砂混凝土施工流程,阐述了珠光砂混凝土在冬季施工的技术要点,并经过试验及实测数据,计算确定了搅拌水的温度,采用经济性良好、可行性强的热水搅拌措施提高拌合物的温度,从而保证珠光砂混凝土的施工质量。%Integrating with specific engineering case and perlite concrete construction procedure,it describes the technological points of perlite concrete winter construction.Through experiments and actual survey data,it calculates and determines the mixing water temperature,and adopts economic and feasible hot water mixing measures to improve the mixture temperature,so as to guarantee the construction quality of perlite concrete.

  10. PROPERTIES OF THE FINE-GRAINED CONCRETE RECEIVED AT NEGATIVE TEMPERATURES

    Directory of Open Access Journals (Sweden)

    Burenina O. N.

    2015-10-01

    Full Text Available Researches of fine-grained concrete testify the possibility of using mineral mechanically activated and nano-additives in a complex with the anti-frost additives providing the organization of production of concrete works at negative air temperatures that is especially important for the Arctic regions

  11. Properties of high-workability concrete with recycled concrete aggregate

    Directory of Open Access Journals (Sweden)

    Safiuddin

    2011-01-01

    Full Text Available This study presents the effects of recycled concrete aggregate (RCA on the key fresh and hardened properties of concrete. RCA was used to produce high-workability concrete substituting 0-100% natural coarse aggregate (NCA by weight. The slump and slump flow of fresh concretes were determined to ensure high workability. In addition, the compressive, flexural and splitting tensile strengths, modulus of elasticity, and permeable voids of hardened concretes were determined. The test results revealed that RCA significantly decreased the workability of concrete. RCA also affected the compressive strength, modulus of elasticity, and permeable voids of concrete. At the age of 28 days, the concrete with 100% RCA provided 12.2% lower compressive strength and 17.7% lesser modulus of elasticity than the control concrete. Also, 100% RCA increased the permeable voids of 28-day old concrete by 8.2%. However, no significant negative impact of RCA was observed on the flexural and splitting tensile strengths of concrete.

  12. Early Property Development in Concrete

    DEFF Research Database (Denmark)

    Normann, Gitte; Munch-Petersen, Christian

    2014-01-01

    The Freiesleben Maturity function is widely used for planning of execution. We tested if for concrete with and without fly ash. The test showed surprisingly that the maturity function in general is not valid. We found that curing at high temperature gave a significant decrease in strength. Fly ash...... appears to reduce this decrease somewhat. We also examined the resistance against chloride penetration for the different concrete types. The resistance was reduced at high temperatures for concrete without fly ash. For concrete with fly ash, it was the opposite; concrete with fly ash obtained higher...

  13. Life Cycle Assessment of Concrete

    Energy Technology Data Exchange (ETDEWEB)

    Sjunnesson, Jeannette

    2005-09-15

    This is an environmental study on concrete that follows the standard protocol of life cycle assessment (LCA). The study is done for two types of concrete, ordinary and frost-resistant concrete, and has an extra focus on the superplasticizers used as admixtures. The utilization phase is not included in this study since the type of construction for which the concrete is used is not defined and the concrete is assumed to be inert during this phase. The results show that it is the production of the raw material and the transports involved in the life cycle of concrete that are the main contributors to the total environmental load. The one single step in the raw material production that has the highest impact is the production of cement. Within the transportation operations the transportation of concrete is the largest contributor, followed by the transportation of the cement. The environmental impact of frost-resistant concrete is between 24-41 % higher than that of ordinary concrete due to its higher content of cement. Superplasticizers contribute with approximately 0.4-10.4 % of the total environmental impact of concrete, the least to the global warming potential (GWP) and the most to the photochemical ozone creation potential (POCP). Also the toxicity of the superplasticizers is investigated and the conclusion is that the low amount of leakage of superplasticizers from concrete leads to a low risk for the environment and for humans.

  14. An historical examination of concrete

    International Nuclear Information System (INIS)

    The requirement that concrete in nuclear waste repositories be stable physically and chemically for hundreds, if not thousands, of years has initiated studies of ancient and old concretes. The history of cement and concrete is described. The oldest know concrete, from Yugoslavia, is ca. 7,500 years old. Concrete was used in many ancient civilisations, including those of Egypt, Greece and Rome. Ancient concretes were usually based upon lime, but sometimes gypsum was used. Pure lime concretes hardened by atomospheric carbonation but the Ancients, in particular the Romans, also employed hydraulic limes and discovered pozzolanas to make superior concretes which, upon hardening, contained complex cementitious hydrates including calcium-silicate-hydrate (CSH), the principal binding element in Portland cement concrete. Portland cement was not invented until 1824 or later and consists principally of calcium silicates formed by clinkerisation of a mixture of limestone and clay in carefully measured proportions. The cement sets hydraulically to form, principally, calcium hydroxide and CSH, the latter being an amorphous or semi-amorphous substance of variable composition. The published literature relating to the analysis of old and ancient cements and concretes is reviewed. A suite of samples spanning the history of concrete has been obtained. A variety of physical and chemical techniques have been employed to characterise these samples. (author)

  15. Shear strength of palm oil clinker concrete beams

    International Nuclear Information System (INIS)

    Highlights: ► Palm oil clinker can be used as lightweight aggregate for the production of structural concrete. ► The palm oil clinker concrete can be classified as lightweight concrete. ► Full scale reinforced palm oil clinker concrete beams without shear reinforcement were tested. ► The CSA based design equation can be used for the prediction of shear capacity with a limit. - Abstract: This paper presents experimental results on the shear behavior of reinforced concrete beams made of palm oil clinker concrete (POCC). Palm oil clinker (POC) is a by-product of palm oil industry and its utilization in concrete production not only solves the problem of disposing this solid waste but also helps to conserve natural resources. Seven reinforced POCC beams without shear reinforcement were fabricated and their shear behavior was tested. POCC has been classified as a lightweight structural concrete with air dry density less than 1850 kg/m3 and a 28-day compressive strength more than 20 MPa. The experimental variables which have been considered in this study were the POCC compressive strength, shear span–depth ratio (a/d) and the ratio of tensile reinforcement (ρ). The results show that the failure mode of the reinforced POCC beam is similar to that of conventional reinforced concrete beam. In addition, the shear equation of the Canadian Standard Association (CSA) can be used in designing reinforced POCC beam with ρ ⩾ 1. However, a 0.5 safety factor should be included in the formula for ρ < 1

  16. Phase-selective entrainment of nonlinear oscillator ensembles

    Science.gov (United States)

    Zlotnik, Anatoly; Nagao, Raphael; Kiss, István Z.; Li-Shin, Jr.

    2016-03-01

    The ability to organize and finely manipulate the hierarchy and timing of dynamic processes is important for understanding and influencing brain functions, sleep and metabolic cycles, and many other natural phenomena. However, establishing spatiotemporal structures in biological oscillator ensembles is a challenging task that requires controlling large collections of complex nonlinear dynamical units. In this report, we present a method to design entrainment signals that create stable phase patterns in ensembles of heterogeneous nonlinear oscillators without using state feedback information. We demonstrate the approach using experiments with electrochemical reactions on multielectrode arrays, in which we selectively assign ensemble subgroups into spatiotemporal patterns with multiple phase clusters. The experimentally confirmed mechanism elucidates the connection between the phases and natural frequencies of a collection of dynamical elements, the spatial and temporal information that is encoded within this ensemble, and how external signals can be used to retrieve this information.

  17. Entrainment of heterogeneous glycolytic oscillations in single cells

    CERN Document Server

    Gustavsson, A -K; Mehlig, B; Goksör, M

    2015-01-01

    Cell signaling, gene expression, and metabolism are affected by cell-cell heterogeneity and random changes in the environment. The effects of such fluctuations on cell signaling and gene expression have recently been studied intensively using single-cell experiments. In metabolism heterogeneity may be particularly important because it may affect synchronisation of metabolic oscillations, an important example of cell-cell communication. This synchronisation is notoriously difficult to describe theoretically as the example of glycolytic oscillations shows: neither is the mechanism of glycolytic synchronisation understood nor the role of cell-cell heterogeneity. To pin down the mechanism and to assess its robustness and universality we have experimentally investigated the entrainment of glycolytic oscillations in individual yeast cells by periodic external perturbations. We find that oscillatory cells synchronise through phase shifts and that the mechanism is insensitive to cell heterogeneity (robustness) and si...

  18. Spontaneous tempo and rhythmic entrainment in a bonobo (Pan paniscus).

    Science.gov (United States)

    Large, Edward W; Gray, Patricia M

    2015-11-01

    The emergence of speech and music in the human species represent major evolutionary transitions that enabled the use of complex, temporally structured acoustic signals to coordinate social interaction. While the fundamental capacity for temporal coordination with complex acoustic signals has been shown in a few distantly related species, the extent to which nonhuman primates exhibit sensitivity to auditory rhythms remains controversial. In Experiment 1, we assessed spontaneous motor tempo and tempo matching in a bonobo (Pan paniscus), in the context of a social drumming interaction. In Experiment 2, the bonobo spontaneously entrained and synchronized her drum strikes within a range around her spontaneous motor tempo. Our results are consistent with the hypothesis that the evolution of acoustic communication builds upon fundamental neurodynamic mechanisms that can be found in a wide range of species, and are recruited for social interactions. PMID:26147705

  19. Turbulent mixing and entrainment in a gravity current

    Energy Technology Data Exchange (ETDEWEB)

    Ecke, Robert E [Los Alamos National Laboratory; Odier, Philippe [ENS-LYON, FRANCE; Chen, Jun [PURDUE UNIV.

    2010-01-01

    We present an experimental study of the mixing processes in a gravity current. The turbulent transport of momentum and buoyancy can be described in a very direct and compact form by a Prandtl mixing length model: the turbulent vertical fluxes of momentum and buoyancy are found to scale quadratically with the vertical mean gradients of velocity and density. The scaling coefficient is the square of the mixing lenth, approximately constant over the mixing zone of the stratified shear layer. We show how, in different flow configurations, this length can be related to the shear length of the flow ({var_epsilon}/{partial_derivative}{sub z}u{sup 3}){sup 1/2}. We also study the fluctuations of the momentum and density turbulent fluxes, showing how they relate to the mixing phenomena, and to the entrainment/detrainment balance.

  20. Near-field entrainment in black smoker plumes

    Science.gov (United States)

    Smith, J. E.; Germanovich, L. N.; Lowell, R. P.

    2013-12-01

    In this work, we study the entrainment rate of the ambient fluid into a plume in the extreme conditions of hydrothermal venting at ocean floor depths that would be difficult to reproduce in the laboratory. Specifically, we investigate the flow regime in the lower parts of three black smoker plumes in the Main Endeavour Field on the Juan de Fuca Ridge discharging at temperatures of 249°C, 333°C, and 336°C and a pressure of 21 MPa. Such flow conditions are typical for ocean floor hydrothermal venting but would be difficult to reproduce in the laboratory. The centerline temperature was measured at several heights in the plume above the orifice. Using a previously developed turbine flow meter, we also measured the mean flow velocity at the orifice. Measurements were conducted during dives 4452 and 4518 on the submersible Alvin. Using these measurements, we obtained a range of 0.064 - 0.068 for values of the entrainment coefficient α, which is assumed constant near the orifice. This is half the value of α ≈ 0.12 - 0.13 that would be expected for plume flow regimes based on the existing laboratory results and field measurements in lower temperature and pressure conditions. In fact, α = 0.064 - 0.068 is even smaller than the value of α ≈ 0.075 characteristic of jet flow regimes and appears to be the lowest reported in the literature. Assuming that the mean value α = 0.066 is typical for hydrothermal venting at ocean floor depths, we then characterized the flow regimes of 63 black smoker plumes located on the Endeavor Segment of the Juan de Fuca Ridge. Work with the obtained data is ongoing, but current results indicate that approximately half of these black smokers are lazy in the sense that their plumes exhibit momentum deficits compared to the pure plume flow that develops as the plume rises. The remaining half produces forced plumes that show the momentum excess compared to the pure plumes. The lower value of the entrainment coefficient has important

  1. Determination of human EEG alpha entrainment ERD/ERS using the continuous complex wavelet transform

    Science.gov (United States)

    Chorlian, David B.; Porjesz, Bernice; Begleiter, Henri

    2003-04-01

    Alpha entrainment caused by exposure to a background stimulus continuously flickering at a rate of 8 1/3 Hz was affected by the appearance of a foreground target stimulus to which the subjects were requested to press a button. With the use of bipolar derivations (to reduce volume conduction effects), scalp recorded EEG potentials were subjected to a continuous wavelet transform using complex Morlet wavelets at a range of scales. Complex Morlet wavelets were used to calculate efficiently instantaneous amplitudes and phases on a per-trial basis, rather than using the Hilbert transform on band-pass filtered data. Multiple scales were employed to contrast the pattern of alpha activity with those in other bands, and to determine whether the harmonics observed in the spectral analysis of the data were simply a result of the non-sinusoidal response to the entraining signal or a distinct neural phenomenon. We were thus able to calculate desynchronization/resynchronization for both the entrained and non-entrained alpha activity. The occurance of the target stimulus caused a sharp increase in amplitude in both the entrained and non-entrained alpha activity, followed by a sharp decrease, and then a return to baseline, over a period of 2.5 seconds. However, the entrained alpha activity showed a much more rapid recovery than non-entrained activity.

  2. Quantification of the effect of oil layer thickness on entrainment of surface oil

    NARCIS (Netherlands)

    Zeinstra-Helfrich, M.; Koops, W.; Dijkstra, K.; Murk, A.J.

    2015-01-01

    This study quantifies the effect of oil layer thickness on entrainment and dispersion of oil into seawater, using a plunging jet with a camera system. In contrast to what is generally assumed, we revealed that for the low viscosity “surrogate MC252 oil” we used, entrainment rate is directly proporti

  3. Accuracy of circadian entrainment under fluctuating light conditions : Contributions of phase and period responses

    NARCIS (Netherlands)

    Beersma, DGM; Daan, S; Hut, RA

    1999-01-01

    The accuracy with which a circadian pacemaker can entrain to an environmental 24-h zeitgeber signal depends on (a) characteristics of the entraining signal and (b) response characteristics and intrinsic stability of the pacemaker itself. Position of the sun, weather conditions, shades, and behaviora

  4. Bubble-type gas entrainment into liquid from free surface by vortex

    International Nuclear Information System (INIS)

    A gas entrainment rate into liquid by a vortex formed on the free surface was examined experimentally. Water flowed into a cylindrical vessel from a wall tangentially. Swirl flow was formed in the vessel, and then water left from the bottom outlet of the vessel. The flow state of the entrainment was visually observed by using a high speed video camera. The gas entrainment rate into water was measured. A stable vortex was formed in the test vessel. When the flow velocity; the velocity at the bottom outlet, was low, a single bubble was periodically torn off from the bottom tip of the vortex and the bubble-type gas entrainment was observed. As the flow rate was increased, the bottom tip of the vortex penetrated into the outlet pipe and the bubble-type gas entrainment continued. A further increase in the flow velocity resulted in the transition from the bubble-type gas entrainment to the vortex-type gas entrainment and the gas entrainment rate considerably increased with the flow velocity. After the vortex tip penetrated into the outlet pipe, the rotation speed of the vortex decayed. As a result of it, the Kelvin-Helmholtz instability wave length got long and the size of the generated bubble became large. Then, the outlet pipe was filled with the large bubbles and the flow state in the outlet pipe turned to the slug/churn flow and a large amount of gas began to be carried out form the test vessel. (author)

  5. The importance of entrainment and bulking on debris flow runout modeling: examples from the Swiss Alps

    Science.gov (United States)

    Frank, F.; McArdell, B. W.; Huggel, C.; Vieli, A.

    2015-11-01

    This study describes an investigation of channel-bed entrainment of sediment by debris flows. An entrainment model, developed using field data from debris flows at the Illgraben catchment, Switzerland, was incorporated into the existing RAMMS debris-flow model, which solves the 2-D shallow-water equations for granular flows. In the entrainment model, an empirical relationship between maximum shear stress and measured erosion is used to determine the maximum potential erosion depth. Additionally, the average rate of erosion, measured at the same field site, is used to constrain the erosion rate. The model predicts plausible erosion values in comparison with field data from highly erosive debris flow events at the Spreitgraben torrent channel, Switzerland in 2010, without any adjustment to the coefficients in the entrainment model. We find that by including bulking due to entrainment (e.g., by channel erosion) in runout models a more realistic flow pattern is produced than in simulations where entrainment is not included. In detail, simulations without entrainment show more lateral outflow from the channel where it has not been observed in the field. Therefore the entrainment model may be especially useful for practical applications such as hazard analysis and mapping, as well as scientific case studies of erosive debris flows.

  6. Parameterization of entrainment in a sheared convective boundary layer using a first-order jump model

    NARCIS (Netherlands)

    Kim, S.W.; Park, S.U.; Pino, D.; Vilà-Guerau de Arellano, J.

    2006-01-01

    Basic entrainment equations applicable to the sheared convective boundary layer (CBL) are derived by assuming an inversion layer with a finite depth, i.e., the first-order jump model. Large-eddy simulation data are used to determine the constants involved in the parameterizations of the entrainment

  7. Application of Fly Ash from Solid Fuel Combustion in Concrete

    DEFF Research Database (Denmark)

    Pedersen, Kim Hougaard

    2008-01-01

    Nordjyllandsværket, unit 3; 3) post treatment of fly ash to lower its AEA adsorptivity. The foam index test is the method usually employed to determine the degree of fly ash interference with AEAs in concrete. The test involves the use of commercial AEAs and visual observation of foam stability. These facts reduce...... with implementation of low-NOx combustion technologies. The present thesis concerns three areas of importance within this field: 1) testing of fly ash adsorption behavior; 2) the influence of fuel type and combustion conditions on the ash adsorption behaviour including full-scale experiments at the power plant...... has a low sensitivity toward small variations in AEA adsorption between different fly ashes and it requires further work before a finished procedure is accomplished. Finally, it was shown that changes in temperature affect both test methods. Pulverized fuel has been combusted in an entrained flow...

  8. How oil properties and layer thickness determine the entrainment of spilled surface oil.

    Science.gov (United States)

    Zeinstra-Helfrich, Marieke; Koops, Wierd; Murk, Albertinka J

    2016-09-15

    Viscosity plays an important role in dispersion of spilled surface oil, so does adding chemical dispersants. For seven different oil grades, entrainment rate and initial droplet size distribution were investigated using a plunging jet apparatus with coupled camera equipment and subsequent image analysis. We found that amount of oil entrained is proportional to layer thickness and largely independent of oil properties: A dispersant dose of 1:200 did not result in a significantly different entrainment rate compared to no dispersants. Oil viscosity had a minor to no influence on entrainment rate, until a certain threshold above which entrainment was impeded. The mean droplet size scales with the modified Weber number as described by Johansen. The obtained results can help improve dispersion algorithms in oil spill fate and transport models, to aid making an informed decision about application of dispersants.

  9. How oil properties and layer thickness determine the entrainment of spilled surface oil.

    Science.gov (United States)

    Zeinstra-Helfrich, Marieke; Koops, Wierd; Murk, Albertinka J

    2016-09-15

    Viscosity plays an important role in dispersion of spilled surface oil, so does adding chemical dispersants. For seven different oil grades, entrainment rate and initial droplet size distribution were investigated using a plunging jet apparatus with coupled camera equipment and subsequent image analysis. We found that amount of oil entrained is proportional to layer thickness and largely independent of oil properties: A dispersant dose of 1:200 did not result in a significantly different entrainment rate compared to no dispersants. Oil viscosity had a minor to no influence on entrainment rate, until a certain threshold above which entrainment was impeded. The mean droplet size scales with the modified Weber number as described by Johansen. The obtained results can help improve dispersion algorithms in oil spill fate and transport models, to aid making an informed decision about application of dispersants. PMID:27345705

  10. The performative pleasure of imprecision: a diachronic study of entrainment in music performance.

    Science.gov (United States)

    Geeves, Andrew; McIlwain, Doris J; Sutton, John

    2014-01-01

    This study focuses in on a moment of live performance in which the entrainment amongst a musical quartet is threatened. Entrainment is asymmetric in so far as there is an ensemble leader who improvises and expands the structure of a last chorus of a piece of music beyond the limits tacitly negotiated during prior rehearsals and performances. Despite the risk of entrainment being disturbed and performance interrupted, the other three musicians in the quartet follow the leading performer and smoothly transition into unprecedented performance territory. We use this moment of live performance to work back through the fieldwork data, building a diachronic study of the development and bases of entrainment in live music performance. We introduce the concept of entrainment and profile previous theory and research relevant to entrainment in music performance. After outlining our methodology, we trace the evolution of the structure of the piece of music from first rehearsal to final performance. Using video clip analysis, interviews and field notes we consider how entrainment shaped and was shaped by the moment of performance in focus. The sense of trust between quartet musicians is established through entrainment processes, is consolidated via smooth adaptation to the threats of disruption. Non-verbal communicative exchanges, via eye contact, gesture, and spatial proximity, sustain entrainment through phase shifts occurring swiftly and on the fly in performance contexts. These exchanges permit smooth adaptation promoting trust. This frees the quartet members to play with the potential disturbance of equilibrium inherent in entrained relationships and to play with this tension in an improvisatory way that enhances audience engagement and the live quality of performance.

  11. The performative pleasure of imprecision: a diachronic study of entrainment in music performance

    Directory of Open Access Journals (Sweden)

    Andrew eGeeves

    2014-10-01

    Full Text Available This study focuses in on a moment of live performance in which the entrainment amongst a musical quartet is threatened. Entrainment is asymmetric in so far as there is an ensemble leader who improvises and expands the structure of a last chorus of a piece of music beyond the limits tacitly negotiated during prior rehearsals and performances. Despite the risk of entrainment being disturbed and performance interrupted, the other three musicians in the quartet follow the leading performer and smoothly transition into unprecedented performance territory. We use this moment of live performance to work back through the fieldwork data, building a diachronic study of the development and bases of entrainment in live music performance. We introduce the concept of entrainment and profile previous theory and research relevant to entrainment in music performance. After outlining our methodology, we trace the evolution of the structure of the piece of music from first rehearsal to final performance. Using video clip analysis, interviews and field notes we consider how entrainment shaped and was shaped by the moment of performance in focus. The sense of trust between quartet musicians is established through entrainment processes, is consolidated via smooth adaptation to the threats of disruption. Nonverbal communicative exchanges, via eye contact, gesture and spatial proximity, sustain entrainment through phase shifts occurring swiftly and on the fly in performance contexts. These exchanges permit smooth adaptation promoting trust. This frees the quartet members to play with the potential disturbance of equilibrium inherent in entrained relationships and to play with this tension in an improvisatory way that enhances audience engagement and the live quality of performance.

  12. Micro Environmental Concrete

    Science.gov (United States)

    Lanez, M.; Oudjit, M. N.; Zenati, A.; Arroudj, K.; Bali, A.

    Reactive powder concretes (RPC) are characterized by a particle diameter not exceeding 600 μm and having very high compressive and tensile strengths. This paper describes a new generation of micro concrete, which has an initial as well as a final high physicomechanical performance. To achieve this, 15% by weight of the Portland cement have been substituted by materials rich in Silica (Slag and Dune Sand). The results obtained from the tests carried out on the RPC show that compressive and tensile strengths increase when incorporating the addition, thus improving the compactness of mixtures through filler and pozzolanic effects. With a reduction in the aggregate phase in the RPC and the abundance of the dune sand (southern of Algeria) and slag (industrial by-product of the blast furnace), the use of the RPC will allow Algeria to fulfil economical as well as ecological requirements.

  13. Thermal Insulating Concrete Wall Panel Design for Sustainable Built Environment

    OpenAIRE

    Ao Zhou; Kwun-Wah Wong; Denvid Lau

    2014-01-01

    Air-conditioning system plays a significant role in providing users a thermally comfortable indoor environment, which is a necessity in modern buildings. In order to save the vast energy consumed by air-conditioning system, the building envelopes in envelope-load dominated buildings should be well designed such that the unwanted heat gain and loss with environment can be minimized. In this paper, a new design of concrete wall panel that enhances thermal insulation of buildings by adding a gyp...

  14. Drying of Concrete

    DEFF Research Database (Denmark)

    Hansen, Kurt Kielsgaard; Geiker, Mette Rica; Nygaard, Peter Vagn;

    2002-01-01

    Estimated and measured relative humidity (RH) change during drying are compared for two concretes, 1: w/c=0.46 and 2: w/(c+0.5fa+2sf)=0.50. The estimations were undertaken by means of the Swedish program TorkaS 1.0. Measurements were performed by RH-sensors type Humi-Guard. Drying of 150 mm thick...

  15. Design of ultra-lightweight concrete: towards monolithic concrete structures

    Directory of Open Access Journals (Sweden)

    Yu Qing Liang

    2014-04-01

    Full Text Available This study addresses the development of ultra-lightweight concrete. A moderate strength and an excellent thermal conductivity of the lightweight concrete are set as the design targets. The designed lightweight aggregates concrete is targeted to be used in monolithic concrete façade structure, performing as both load bearing element and thermal insulator. The developed lightweight concrete shows excellent thermal properties, with a low thermal conductivity of about 0.12 W/(m·K; and moderate mechanical properties, with 28-day compressive strengths of about 10-12 N/mm . This combination of values exceeds, to the researchers’ knowledge, the performance of all other lightweight building materials. Furthermore, the developed lightweight concrete possesses excellent durability properties.

  16. Combined air and water pollution control system

    Science.gov (United States)

    Wolverton, Billy C. (Inventor); Jarrell, Lamont (Inventor)

    1990-01-01

    A bioaquatic air pollution control system for controlling both water and atmospheric pollution is disclosed. The pollution control system includes an exhaust for directing polluted gases out of a furnace and a fluid circulating system which circulates fluid, such as waste water, from a source, past the furnace where the fluid flow entrains the pollutants from the furnace. The combined fluid and pollutants are then directed through a rock/plant/microbial filtering system. A suction pump pumps the treated waste water from the filter system past the exhaust to again entrain more pollutants from the furnace where they are combined with the fluid (waste water) and directed to the filter system.

  17. Radiolysis of concrete

    International Nuclear Information System (INIS)

    A computer based radiation chemical program has been used to simulate experiments with gamma and alpha radiolysis in concrete. The experiments have been performed at Savannah River by Ned Bibler and co-workers. The calculations showed that the gas yields were very sensitive to the pH of the water phase. At a pH of 12.3 fairly good agreement was obtained between measured and calculated gas yields, assuming that the gas production only took place in the free water phase of the concrete. The following main conclusions could be made from both measurements and calculations: 1/ A steady state is obtained by gamma radiolysis of a NO3 free concrete. 2/ The yields are higher and a steady state is not obtained if NO3 is present. The yields are higher and a steady state is not obtained by alpha radiolysis. Calculations were also carried out on radiolysis from cladding hull waste stored in a cement matrix assuming both alpha and beta radiation. In the presence of an aerated gas phase a steady state pressure of more than 0.21 MPa was obtained.(author)

  18. Towards Better Understanding of Concrete Containing Recycled Concrete Aggregate

    OpenAIRE

    Hisham Qasrawi; Iqbal Marie

    2013-01-01

    The effect of using recycled concrete aggregates (RCA) on the basic properties of normal concrete is studied. First, recycled aggregate properties have been determined and compared to those of normal aggregates. Except for absorption, there was not a significant difference between the two. Later, recycled aggregates were introduced in concrete mixes. In these mixes, natural coarse aggregate was partly or totally replaced by recycled aggregates. Results show that the use of recycled aggregates...

  19. Repercussions on concrete permeability due to recycled concrete aggregate

    OpenAIRE

    Gómez Soberón, José Manuel Vicente; Agulló Fité, Luís; Vázquez Ramonich, Enric

    2001-01-01

    This paper presents an experimental analysis of recycled concrete (RC) in which the natural aggregates are replaced by recycled concrete aggregates (RCA). This experimental program covers the specifications of the aggregates employed, together with that of the concrete that is manufactured with them. The considerable effect on the permeability of RC that is produced by the use of RCA is described and discussed. Tests reveal considerable increase in permeability of RC in compari...

  20. INVESTIGATION ON MECHANICAL PROPERTIES OF STRUCTURAL LIGHTWEIGHT CONCRETE MADE WITH PUMICE AGGREGATE

    Directory of Open Access Journals (Sweden)

    Selçuk TÜRKEL

    2007-03-01

    Full Text Available In this study, structural lightweight concrete mixtures are produced by using Kayseri pumice aggregate. The other constituent materials used in producing the lightweight concrete mixtures are; CEM I 42.5 cement as binder, silica fume and fly ash as mineral admixtures. The following properties are determined; slump, unit weight and air content of fresh mix, as well as unit weight, compressive strength, splitting tensile strength and flexural strength of hardened concrete. Test results show that the lightweight concrete mixtures prepared from Kayseri pumice have compressive strength far above 17.2 MPa proposed by ACI 213R-87 for structural lightweight concrete. Besides, the lightweight concretes produced in this study meet LC 20/22 and LC 25/28 strength classes given by TS EN 206-1.

  1. Flow Dynamics and Sediment Entrainment in Natural Turbidity Currents Inferred from Numerical Modeling

    Science.gov (United States)

    Traer, M. M.; Hilley, G. E.; Fildani, A.

    2009-12-01

    Submarine turbidity currents derive their momentum from gravity acting upon the density contrast between sediment-laden and clear water, and so unlike fluvial systems, the dynamics of such flows are inextricably linked to the rates at which they deposit and entrain sediment. We have analyzed the sensitivity of the growth and maintenance of turbidity currents to sediment entrainment and deposition using the layer-averaged equations of conservation of fluid and sediment mass, and conservation of momentum and turbulent kinetic energy. Our model results show that the dynamics of turbidity currents are extremely sensitive to the functional form and empirical constants of the relationship between sediment entrainment and friction velocity. Data on the relationship between sediment entrainment and friction velocity for submarine density flows are few and as a result, entrainment formulations are populated with data from sub-aerial flows not driven by the density contrast between clear and turbid water. If we entertain the possibility that sediment entrainment in sub-aerial rivers is different than in dense underflows, flow parameters such as velocity, height, and concentration were found nearly impossible to predict beyond a few hundred meters based on the limited laboratory data available that constrain the sediment entrainment process in turbidity currents. The sensitivity of flow dynamics to the functional relationship between friction velocity and sediment entrainment indicates that independent calibration of a sediment entrainment law in the submarine environment is necessary to realistically predict the dynamics of these flows and the resulting patterns of erosion and deposition. To calibrate such a relationship, we have developed an inverse methodology that utilizes existing submarine channel morphology as a means of constraining the sediment entrainment function parameters. We use a Bayesian Metropolis-Hastings sampler to determine the sediment entrainment

  2. Concrete with superabsorbent polymers (SAP) - experience from the Fehmarn field exposure station in Rødbyhavn

    DEFF Research Database (Denmark)

    Hasholt, Marianne Tange; Pade, Claus

    2011-01-01

    A field exposure station has been established in Rødbyhavn Habour. One of the concrete types tested is with superabsorbent polymer (SAP) - a new type of additive, which can be used to mitigate self-desiccation and to control air void structure. This paper presents results from the extensive...... laboratory test program, which was conducted before test panels were placed in Rødbyhavn Habour. Results show that when using SAP, it is possible to produce concrete with a pre-defined air void structure. Strength and transport properties are comparable to the properties of a reference concrete, but results...

  3. Potential for carbon adsorption on concrete: surface XPS analyses.

    Science.gov (United States)

    Haselbach, Liv M; Ma, Shuguo

    2008-07-15

    The concrete industry is a contributor to the global carbon cycle particularly with respect to the contribution of carbon dioxide in the manufacturing of cement (calcination). The reverse reaction of carbonation is known to occur in concrete, but is usually limited to exterior surfaces exposed to carbon dioxide and humidity in the air. As alternate concrete uses expand which have more surface area, such as crushed concrete for recycling, it is important to understand surface adsorption of carbon dioxide and the positive impacts it might have on the carbon cycle. X-ray photoelectron spectroscopy (XPS) is used in this study to evaluate carbon species on hydrated cement mortar surfaces. Initial estimates for carbon absorption in concrete using othertechniques predictthe potential for carbonate species to be a fraction of the calcination stoichiometric equivalent The XPS results indicate that there is a rapid and substantial uptake of carbon dioxide on the surfaces of these mortars, sometimes exceeding the calcination stoichiometric equivalents, indicative of carbon dioxide surface complexation species. On pure calcite, the excess is on the order of 30%. This accelerated carbon dioxide surface adsorption phenomenon may be importantfor determining novel and effective carbon sequestration processes using recycled concrete. PMID:18754389

  4. Mechanical Properties of Fiber Reinforced Lightweight Concrete Containing Surfactant

    Directory of Open Access Journals (Sweden)

    Yoo-Jae Kim

    2010-01-01

    Full Text Available Fiber reinforced aerated lightweight concrete (FALC was developed to reduce concrete's density and to improve its fire resistance, thermal conductivity, and energy absorption. Compression tests were performed to determine basic properties of FALC. The primary independent variables were the types and volume fraction of fibers, and the amount of air in the concrete. Polypropylene and carbon fibers were investigated at 0, 1, 2, 3, and 4% volume ratios. The lightweight aggregate used was made of expanded clay. A self-compaction agent was used to reduce the water-cement ratio and keep good workability. A surfactant was also added to introduce air into the concrete. This study provides basic information regarding the mechanical properties of FALC and compares FALC with fiber reinforced lightweight concrete. The properties investigated include the unit weight, uniaxial compressive strength, modulus of elasticity, and toughness index. Based on the properties, a stress-strain prediction model was proposed. It was demonstrated that the proposed model accurately predicts the stress-strain behavior of FALC.

  5. Degradation of permeability resistance of high strength concrete after combustion

    Institute of Scientific and Technical Information of China (English)

    Min LI; Hongtao KAO; Chunxiang QIAN

    2008-01-01

    To evaluate the remaining durability of con-crete materials after combustion, the permeability of high strength concrete (HSC) after combustion was studied. The transport behavior of chloride ion, water and air in concrete after combustion and the effect of temperature, strength grade, and aggregation on the permeability of HSC after combustion are investigated by chloride ion permeability coefficient (Dc), water permeability coef-ficient (Dw) and air permeability coefficient (Da). The experiment results show that all three permeability coeffi-cients commendably reflect changes of permeability. The permeability coefficient increases with the evaluation tem-perature. After the same temperature, the permeability coefficient of HSC is lower than that of normal strength concrete (NSC). However, the degree of degradation of permeability coefficient of HSC is greater than that of NSC. The permeability resistance of HSC containing limestone is better than that of HSC containing basalt. Combining changes of compressive strength and per-meability, the remaining durability of concrete materials after combustion is appropriately evaluated.

  6. Let’s Get Concrete!

    DEFF Research Database (Denmark)

    Jones, Candace; Boxenbaum, Eva

    Scholars emphasize the cognitive or ideational aspects of institutional logics. Less clear is the role of materiality, which is a key aspect of institutional logics, and aesthetic responses to material objects. This study focuses on the introduction of a new building material—concrete— during 1890......-legitimated not only concrete but also stone. Concrete was perceived as merely imitative and thus inauthentic. For concrete to become a legitimate and widely adopted material, architects had to theorize concrete as unique material with distinctive aesthetic possibilities, which led to new kinds of buildings and new...... to 1939 in the architectural profession. Our findings reveal that how professional logics were enacted drove different process for incorporating concrete as a legitimate building material: in France professional and state logics combined to create regulations that governed architects’ use of concrete...

  7. Chlorine signal attenuation in concrete.

    Science.gov (United States)

    Naqvi, A A; Maslehuddin, M; ur-Rehman, Khateeb; Al-Amoudi, O S B

    2015-11-01

    The intensity of prompt gamma-ray was measured at various depths from chlorine-contaminated silica fume (SF) concrete slab concrete specimens using portable neutron generator-based prompt gamma-ray setup. The intensity of 6.11MeV chloride gamma-rays was measured from the chloride contaminated slab at distance of 15.25, 20.25, 25.25, 30.25 and 35.25cm from neutron target in a SF cement concrete slab specimens. Due to attenuation of thermal neutron flux and emitted gamma-ray intensity in SF cement concrete at various depths, the measured intensity of chlorine gamma-rays decreases non-linearly with increasing depth in concrete. A good agreement was noted between the experimental results and the results of Monte Carlo simulation. This study has provided useful experimental data for evaluating the chloride contamination in the SF concrete utilizing gamma-ray attenuation method.

  8. Concrete enclosure to shield a neutron source

    Energy Technology Data Exchange (ETDEWEB)

    Villagrana M, L. E.; Rivera P, E.; De Leon M, H. A.; Soto B, T. G.; Hernandez D, V. M.; Vega C, H. R., E-mail: emmanuelvillagrana@hotmail.com [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Apdo. Postal 336, 98000 Zacatecas (Mexico)

    2012-10-15

    In the aim to design a shielding for a {sup 239}PuBe isotopic neutron source several Monte Carlo calculations were carried out using MCNP5 code. First, a point-like source was modeled in vacuum and the neutron spectrum and the ambient dose equivalent were calculated at several distances ranging from 5 up to 150 cm, these calculations were repeated including air, and a 1 x 1 x 1 m{sup 3} enclosure that was shielded with 5, 15, 20, 25, 30, 50 and 80 cm-thick Portland type concrete walls. At all the points located inside the enclosure neutron spectra from 10{sup -8} up 0.5 MeV were the same regardless the distance from the source showing the room-return effect, for energies larger than 0.5 MeV neutron spectra are diminished as the distance increases. Outside the enclosure it was noticed that neutron spectra becomes -softer- as the concrete thickness increases due to reduction of mean neutron energy. With the ambient dose values the attenuation curve in terms of concrete thickness was calculated. (Author)

  9. Inspection Strategies for Concrete Bridges

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard; Thoft-Christensen, Palle

    1989-01-01

    In this paper an optimal inspection strategy for concrete bridges based on periodic routine and detailed inspections is presented. The failure mode considered is corrosion of the reinforcement due to chlorides. A simple modelling of the corrosion and of the inspection strategy is presented....... The optimal inspection strategy is determined from an optimization problem, where the design variables are time intervals between detailed inspections and the concrete cover. The strategy is illustrated on a simple structure, namely a reinforced concrete beam....

  10. Concrete durability with antigraffiti protection

    OpenAIRE

    Neto, Elsa; Souto, Ana; Camões, Aires; Begonha, Arlindo; Cachim, Paulo

    2014-01-01

    The heritage of fair-faced concrete, largely built in the twentieth century and nowadays recognized as heritage to be protected, is susceptible to attacks by graffiti. Durability of concrete depends on the composition and characteristics of the surface, whereby it is essential to study the effects of anti-graffiti protection systems on the durability of concrete and adopt the appropriate methodology to preserve this heritage. Thus, an experimental program was developed for analyzing changes i...

  11. Optimization of reinforced concrete slabs

    Science.gov (United States)

    Ferritto, J. M.

    1979-01-01

    Reinforced concrete cells composed of concrete slabs and used to limit the effects of accidental explosions during hazardous explosives operations are analyzed. An automated design procedure which considers the dynamic nonlinear behavior of the reinforced concrete of arbitrary geometrical and structural configuration subjected to dynamic pressure loading is discussed. The optimum design of the slab is examined using an interior penalty function. The optimization procedure is presented and the results are discussed and compared with finite element analysis.

  12. Experimental study of high volume fly ash pumping concrete compressive strength early%大掺量粉煤灰泵送混凝土早期抗压强度的试验研究

    Institute of Scientific and Technical Information of China (English)

    刘思海; 侍克斌; 吴福飞

    2014-01-01

    通过理论分析和试验,研究了大掺量粉煤灰对混凝土早期抗压强度及成本的影响。试验所选用的胶凝材料总量为375 kg,以0~55%的粉煤灰替代水泥,减水剂的掺量固定为1.0%,引气剂的掺量固定为1.2‱。通过坍落度及不同龄期抗压强度等对比分析粉煤灰掺量对混凝土和易性及早期强度的影响。结果表明,混凝土早期抗压强度及成本随着粉煤灰掺量的增大而逐渐减小,运用粉煤灰等质量代替水泥(P·O 42.5级水泥)可配制出28 d抗压强度为20 MPa以上,成本大大降低的大掺量粉煤灰混凝土。研究的结论为新疆地区粉煤灰的应用提供了有效途径,有助于制备高性能混凝土。%Through theoretical analysis and test,studied the effect of high volume fly ash on concrete compressive strength and cost. To-tal cementitious materials test for the selected 375 kg,with 0~55%fly ash instead of cement,the amount of superplasticizer was fixed at 1%,dosage of air entraining agent was fixed at 1.2‱.Through the slump and compressive strength of comparative analysis of the influence of fly ash on concrete workability and early strength. The results showed that ,the concrete compressive strength and cost decreased gradu-ally with the increase in the amount of fly ash,fly ash and other quality instead of using cement (42.5 ordinary portland cement)can be made by 28 d compressive strength was more than 20 MPa,a large amount of fly ash can reduce the cost of concrete. Provided an effective way for research conclusion was the application of fly ash in Xinjiang ,contributed to the preparation of high performance concrete.

  13. Entrainment Across a Sheared Density Interface in High Richardson Number Cavity Flow

    Science.gov (United States)

    Williamson, Nicholas; Kirkpartick, Michael; Armfield, Steve

    2015-11-01

    The turbulent entrainment of fluid across a sharp density interface has been examined experimentally in a purging cavity flow. In the experiments, a long straight cavity with sloped entry and exit boundaries is located in the base of a straight open channel. Saline fluid is entrained from the cavity into the overflow. The cavity geometry has been designed to ensure there is no separation of the overflow in the cavity region with the goal of obtaining a single mode of entrainment, related only to the interface properties rather than to cavity specific mechanisms. The bulk entrainment rate has been measured and correlated with bulk Richardson number over Ri = 1 . 0 - 20 at Reynolds number Re = 7100 - 15100 . The entrainment rate is shown to scale with the local bulk Richardson number E ~= CRi - 1 . 38 , very close to the established result for entrainment across a sharp two layer density interface in a recirculating water channel (Strang and Fernando, J Fluid Mech., 428, 2001) but with an order of magnitude lower coefficient C. Experiments instrumented with PIV/LIF were used to relate the bulk Ri to the local gradient Richardson number of the interface. In the cavity setting the interface appears to remain sharper, resulting in larger Rig and reduced entrainment.

  14. Quadrupedal Locomotion-Respiration Entrainment and Metabolic Economy in Cross-Country Skiers.

    Science.gov (United States)

    Boldt, Kevin; Killick, Anthony; Herzog, Walter

    2016-02-01

    A 1:1 locomotion-respiration entrainment is observed in galloping quadrupeds, and is thought to improve running economy. However, this has not been tested directly in animals, as animals cannot voluntarily disrupt this entrainment. The purpose of this study was to evaluate metabolic economy in a human gait involving all four limbs, cross-country skiing, in natural entrainment and forced nonentrainment. Nine elite cross-country skiers roller skied at constant speed using the 2-skate technique. In the first and last conditions, athletes used the natural entrained breathing pattern: inhaling with arm recovery and exhaling with arm propulsion, and in the second condition, the athletes disentrained their breathing pattern. The rate of oxygen uptake (VO2) and metabolic rate (MR) were measured via expired gas analysis. Propulsive forces were measured with instrumented skis and poles. VO2 and MR increased by 4% and 5% respectively when skiers used the disentrained compared with the entrained breathing pattern. There were no differences in ski or pole forces or in timing of the gait cycle between conditions. We conclude that breathing entrainment reduces metabolic cost of cross-country skiing by approximately 4%. Further, this reduction is likely a result of the entrainment rather than alterations in gait mechanics. PMID:26252735

  15. Quadrupedal Locomotion-Respiration Entrainment and Metabolic Economy in Cross-Country Skiers.

    Science.gov (United States)

    Boldt, Kevin; Killick, Anthony; Herzog, Walter

    2016-02-01

    A 1:1 locomotion-respiration entrainment is observed in galloping quadrupeds, and is thought to improve running economy. However, this has not been tested directly in animals, as animals cannot voluntarily disrupt this entrainment. The purpose of this study was to evaluate metabolic economy in a human gait involving all four limbs, cross-country skiing, in natural entrainment and forced nonentrainment. Nine elite cross-country skiers roller skied at constant speed using the 2-skate technique. In the first and last conditions, athletes used the natural entrained breathing pattern: inhaling with arm recovery and exhaling with arm propulsion, and in the second condition, the athletes disentrained their breathing pattern. The rate of oxygen uptake (VO2) and metabolic rate (MR) were measured via expired gas analysis. Propulsive forces were measured with instrumented skis and poles. VO2 and MR increased by 4% and 5% respectively when skiers used the disentrained compared with the entrained breathing pattern. There were no differences in ski or pole forces or in timing of the gait cycle between conditions. We conclude that breathing entrainment reduces metabolic cost of cross-country skiing by approximately 4%. Further, this reduction is likely a result of the entrainment rather than alterations in gait mechanics.

  16. Neurobiological foundations of neurologic music therapy: rhythmic entrainment and the motor system.

    Science.gov (United States)

    Thaut, Michael H; McIntosh, Gerald C; Hoemberg, Volker

    2014-01-01

    Entrainment is defined by a temporal locking process in which one system's motion or signal frequency entrains the frequency of another system. This process is a universal phenomenon that can be observed in physical (e.g., pendulum clocks) and biological systems (e.g., fire flies). However, entrainment can also be observed between human sensory and motor systems. The function of rhythmic entrainment in rehabilitative training and learning was established for the first time by Thaut and colleagues in several research studies in the early 1990s. It was shown that the inherent periodicity of auditory rhythmic patterns could entrain movement patterns in patients with movement disorders (see for a review: Thaut et al., 1999). Physiological, kinematic, and behavioral movement analysis showed very quickly that entrainment cues not only changed the timing of movement but also improved spatial and force parameters. Mathematical models have shown that anticipatory rhythmic templates as critical time constraints can result in the complete specification of the dynamics of a movement over the entire movement cycle, thereby optimizing motor planning and execution. Furthermore, temporal rhythmic entrainment has been successfully extended into applications in cognitive rehabilitation and speech and language rehabilitation, and thus become one of the major neurological mechanisms linking music and rhythm to brain rehabilitation. These findings provided a scientific basis for the development of neurologic music therapy. PMID:25774137

  17. Neurobiological Foundations of Neurologic Music Therapy: Rhythmic Entrainment and the Motor System

    Directory of Open Access Journals (Sweden)

    Michael eThaut

    2015-02-01

    Full Text Available AbstractEntrainment is defined by a temporal locking process in which one system’s motion or signal frequency entrains the frequency of another system. This process is a universal phenomenon that can be observed in physical (e.g., pendulum clocks and biological systems (e.g. fire flies. However, entrainment can also be observed between human sensory and motor systems. The function of rhythmic entrainment in rehabilitative training and learning was established for the first time by Thaut and colleagues in several research studies in the early 1990s. It was shown that the inherent periodicity of auditory rhythmic patterns could entrain movement patterns in patients with movement disorders (see for a review: Thaut et al, 1999. Physiological, kinematic and behavioral movement analysis showed very quickly that entrainment cues not only changed the timing of movement but also improved spatial and force parameters. Mathematical models have shown that anticipatory rhythmic templates as critical time constraints can result in the complete specification of the dynamics of a movement over the entire movement cycle, thereby optimizing motor planning and execution. Furthermore, temporal rhythmic entrainment has been successfully extended into applications in cognitive rehabilitation and speech and language rehabilitation, and thus become one of the major neurological mechanisms linking music and rhythm to brain rehabilitation. These findings provided a scientific basis for the development of Neurologic Music Therapy.

  18. Gas entrainment in the IHX vessel of top-entry loop-type LMFBR

    Energy Technology Data Exchange (ETDEWEB)

    Eguchi, Y. (FBR Development Dept., Japan Atomic Power Co., Tokyo (Japan)); Yamamoto, K. (FBR Development Dept., Japan Atomic Power Co., Tokyo (Japan)); Funada, T. (FBR Development Dept., Japan Atomic Power Co., Tokyo (Japan)); Tanaka, N. (Central Research Inst. of Electric Power Industry, Tokyo (Japan)); Moriya, S. (Central Research Inst. of Electric Power Industry, Tokyo (Japan)); Tanimoto, K. (Mitsubishi Heavy Industries Ltd., Tokyo (Japan)); Ogura, K. (Toshiba Corp., Tokyo (Japan)); Suzuki, T. (Hitachi Ltd., Tokyo (Japan)); Maekawa, I. (Kawasaki Heavy Industries Ltd., Tokyo (Japan))

    1994-02-01

    The effects of scale and fluid properties on gas entrainment onset were experimentally studied for the free surface flow in an IHX vessel of a proposed Japanese demonstration FBR. Water experiments were performed using the 1/10-th, 1/6-th, 1/3-rd and 1/1.6-th scaled models of the IHX. The experimental results indicate that the scale has a strong effect on gas entrainment onset and that the critical Fr number decreases in proportion to the -0.5-th power of the scale. Applicability of a computational method to the gas entrainment is also discussed by comparing computational and experimental results. (orig.)

  19. Effects of entrainment through Oconee Nuclear Station on carbon-14 assimilation rates of phytoplankton

    International Nuclear Information System (INIS)

    Carbon assimilation rates of phytoplankton communities entrained through Oconee Nuclear Station were measured on six dates during 1974. Thermal, mechanical, condenser, and multiple entrainment effects on uptake rates were compared by incubating samples in vitro in controlled-temperature water baths. Duplicate light and dark bottles containing water from four cooling-system locations were exposed to temperatures approximating intake and discharge temperatures. The relationships were variable, but exposure of the hypolimnetic intake water at near-discharge temperatures (thermal effect) stimulated primary productivity in four of six experiments. Multiple entrainment and mechanical effects caused no consistent change in assimilation rates

  20. Experimental study on scale effect on gas entrainment at free surface

    International Nuclear Information System (INIS)

    It is necessary to understand effects of scale and fluid properties on gas entrainment phenomena for prediction of gas entrainment in a fast breeder reactor (FBR). In the present study, three models of different scales but of similar geometry were used for water tests to examine the effects of scale and viscosity. The results have shown that the critical Froude (Fr) number, above which gas entrainment appears, drastically decreases as the scale increase. A prediction method using the Fr-Re map is proposed in the present paper for the sodium flow in an FBR. (orig.)

  1. Investigation of Pressurized Entrained-Flow Kraft Black Liquor Gasification in an Industrially Relevant Environment

    Energy Technology Data Exchange (ETDEWEB)

    Kevin Whitty

    2008-06-30

    The University of Utah's project 'Investigation of Pressurized Entrained-Flow Kraft Black Liquor Gasification in an Industrially Relevant Environment' (U.S. DOE Cooperative Agreement DE-FC26-04NT42261) was a response to U.S. DOE/NETL solicitation DE-PS36-04GO94002, 'Biomass Research and Development Initiative' Topical Area 4-Kraft Black Liquor Gasification. The project began September 30, 2004. The objective of the project was to improve the understanding of black liquor conversion in high pressure, high temperature reactors that gasify liquor through partial oxidation with either air or oxygen. The physical and chemical characteristics of both the gas and condensed phase were to be studied over the entire range of liquor conversion, and the rates and mechanisms of processes responsible for converting the liquor to its final smelt and syngas products were to be investigated. This would be accomplished by combining fundamental, lab-scale experiments with measurements taken using a new semi-pilot scale pressurized entrained-flow gasifier. As a result of insufficient availability of funds and changes in priority within the Office of Biomass Programs of the U.S. Department of Energy, the research program was terminated in its second year. In total, only half of the budgeted funding was made available for the program, and most of this was used during the first year for construction of the experimental systems to be used in the program. This had a severe impact on the program. As a consequence, most of the planned research was unable to be performed. Only studies that relied on computational modeling or existing experimental facilities started early enough to deliver useful results by the time to program was terminated Over the course of the program, small scale (approx. 1 ton/day) entrained-flow gasifier was designed and installed at the University of Utah's off-campus Industrial Combustion and Gasification Research Facility. The system is

  2. A study of annular flows with bubbles in the liquid ring and entrained droplets by means of stochastic analysis techniques

    International Nuclear Information System (INIS)

    By employing stochastic analysis techniques, an experimental study of a large number of annular flows with bubbles in the liquid ring and entrained droplets has been undertaken in the experimental air-water loop FREDLI, in which the information carrier is two visible light beams crossing the diameter of the tube and modulated by the scattering of the photons at the randomly arriving interfaces; also, some earlier neutron noise measurements in the upper part of a commercial BWR core are carefully analyzed. For the BWR measurements, it is shown for the first time that in the upper part of the core, there are usually three peaks in the cross-correlation function and that all noise analytic functions look extraordinarily similar to the corresponding noise analytic functions of some of the investigated annular flows at the FREDLI loop; a plausible explanation of these findings is given. (Auth.)

  3. Entrainment of free troposphere Asian dust/pollution into the marine boundary layer North of Hawai`i during INTEX-B

    Science.gov (United States)

    McNaughton, C.; Clarke, A.; Kapustin, V.; Dibb, J.; Anderson, B.; Browell, E.; Carmichael, G.

    2006-12-01

    During NASA's INTEX-B experiment (April, 2006), regional and global chemical transport models (CTM's) successfully predicted two Asian dust/pollution outbreaks. The dusty airmasses were transported from Asia to the Pacific Ocean north of Hawai`i via the free troposphere (FT) and reached locations as far south the Mauna Loa atmospheric observatory. Five research flights using the NASA DC-8 were flown in order to characterize the long-range transport of trace gases and aerosols from Asia and in order to calibrate/validate both CTM predictions and satellite retrievals. In-flight mapping of the dust/pollution layers using the NASA Langley DIAL LIDAR show a sloping, subsiding Asian airmass entraining into the marine boundary layer (MBL). Using in-situ measurements of the aerosol size distribution, chemistry, optical properties and the increase in light scattering as a function of relative humidity [f(RH)], we are able to characterize and discriminate between MBL air, FT Asian dust/pollution and an external mixture of the two airmasses during entrainment. After entrainment aerosols are removed via wet deposition ahead of the trailing low pressure front. The entire episode is put further into context using models, satellite observations and data from the Mauna Loa Observatory. We include a discussion of dust-flux to the ocean surface due to wet-deposition, a potentially important source of iron to the oligotrophic waters of the North Pacific Subtropical Gyre.

  4. TECHNOLOGICAL PROPERTIES OF CONCRETES AND MORTARS FOR UNDERWATER CONCRETING

    OpenAIRE

    O. V. Anufrieva; B. H. Klochko

    2009-01-01

    The article is about the results of experimental-and-theoretical research of usefulness of mortar and concrete mixes for underwater repair works. It is shown that the developed compositions of hydraulic engineering concretes are characterized by high effectiveness in the corrosive medium.

  5. TECHNOLOGICAL PROPERTIES OF CONCRETES AND MORTARS FOR UNDERWATER CONCRETING

    Directory of Open Access Journals (Sweden)

    O. V. Anufrieva

    2009-03-01

    Full Text Available The article is about the results of experimental-and-theoretical research of usefulness of mortar and concrete mixes for underwater repair works. It is shown that the developed compositions of hydraulic engineering concretes are characterized by high effectiveness in the corrosive medium.

  6. Reduced bleed air extraction for DC-10 cabin air conditioning

    Science.gov (United States)

    Newman, W. H.; Viele, M. R.; Hrach, F. J.

    1980-01-01

    It is noted that a significant fuel savings can be achieved by reducing bleed air used for cabin air conditioning. Air in the cabin can be recirculated to maintain comfortable ventilation rates but the quality of the air tends to decrease due to entrainment of smoke and odors. Attention is given to a development system designed and fabricated under the NASA Engine Component Improvement Program to define the recirculation limit for the DC-10. It is shown that with the system, a wide range of bleed air reductions and recirculation rates is possible. A goal of 0.8% fuel savings has been achieved which results from a 50% reduction in bleed extraction from the engine.

  7. Continuous Reinforced Concrete Beams

    DEFF Research Database (Denmark)

    Hoang, Cao Linh; Nielsen, Mogens Peter

    1996-01-01

    This report deals with stress and stiffness estimates of continuous reinforced concrete beams with different stiffnesses for negative and positive moments e.g. corresponding to different reinforcement areas in top and bottom. Such conditions are often met in practice.The moment distribution...... at the limit state of serviceability is in some simple cases determined by setting up the statical and the compatibility conditions.With these moment distributions, the maximum deflection and the reinforcement stresses at the span middle and at a support are calculated.The results are compared with results...

  8. Kinematics of flow and sediment particles at entrainment and deposition

    Science.gov (United States)

    Antico, Federica; Sanches, Pedro; Aleixo, Rui; Ferreira, Rui M. L.

    2015-04-01

    A cohesionless granular bed subjected to a turbulent open-channel flow is analysed. The key objective is to clarify the kinematics of entrainment and deposition of individual sediment particles. In particular, we quantify a) the turbulent flow field in the vicinity of particles at the instants of their entrainment and of their deposition; b) the initial particle velocity and the particle velocity immediately before returning to rest. The experimental work was performed at the Hydraulics Laboratory of IST-UL in a 12.5 m long, 0.405 m wide glass-walled flume recirculating water and sediment through independent circuits. The granular bed was a 4.0 m long and 2.5 cm deep reach filled with 5 mm diameter glass beads packed (with some vibration) to a void fraction of 0.356, typical of random packing. Upstream the mobile bed reach the bed was composed of glued particles to ensure the development of a boundary layer with the same roughness. Laboratory tests were run under conditions of weak beadload transport with Shields parameters in the range 0.007 to 0.03. Froude numbers ranged from 0.63 to 0.95 while boundary Reynolds numbers were in the range 130 to 300. It was observed that the bed featured patches of regular arrangements: face centered cubic (fcc) or hexagonal close packing (hcp) blocks alternate with and body centered cubic (bcc) blocks. The resulting bed surface exhibits cleavage lines between blocks and there are spatial variations of bed elevation. The option for artificial sediment allowed for a simplified description of particle positioning at the instant of entrainment. In particular support and pivoting angles are found analytically. Skin friction angles were determind experimentally. The only relevant variables are exposure (defined as the ratio of the actual frontal projection of the exposed area to the area of a circle with 5 mm diameter) and protrusion (defined as the vertical distance between the apex of the particle and the mean local bed elevation

  9. Changes in music tempo entrain movement related brain activity.

    Science.gov (United States)

    Daly, Ian; Hallowell, James; Hwang, Faustina; Kirke, Alexis; Malik, Asad; Roesch, Etienne; Weaver, James; Williams, Duncan; Miranda, Eduardo; Nasuto, Slawomir J

    2014-01-01

    The neural mechanisms of music listening and appreciation are not yet completely understood. Based on the apparent relationship between the beats per minute (tempo) of music and the desire to move (for example feet tapping) induced while listening to that music it is hypothesised that musical tempo may evoke movement related activity in the brain. Participants are instructed to listen, without moving, to a large range of musical pieces spanning a range of styles and tempos during an electroencephalogram (EEG) experiment. Event-related desynchronisation (ERD) in the EEG is observed to correlate significantly with the variance of the tempo of the musical stimuli. This suggests that the dynamics of the beat of the music may induce movement related brain activity in the motor cortex. Furthermore, significant correlations are observed between EEG activity in the alpha band over the motor cortex and the bandpower of the music in the same frequency band over time. This relationship is observed to correlate with the strength of the ERD, suggesting entrainment of motor cortical activity relates to increased ERD strength. PMID:25571015

  10. Engine jet entrainment in the near field of an aircraft

    Energy Technology Data Exchange (ETDEWEB)

    Garnier, F.; Jacquin, L.; Laverdant, A. [Office National d`Etudes et de Recherches Aerospatiales (ONERA), 92 - Chatillon (France)

    1997-12-31

    A simplified approach has been applied to analyse the mixing and entrainment processes of the engine exhaust through their interaction with the vortex wake of an aircraft. These investigations are focused on the near filed, extending from exit nozzle to the beginning of the vortex phase (i.e. to about twenty seconds after the wake is generated). This study is performed using an integral model and a numerical simulation for a two-engine large civil aircraft. The properties of the wing-tip vortices on the calculation of the dilution ratio (defined as a tracer concentration) have been shown. The mixing process is also affected by the buoyancy effect, but only after the jet regime, when the trapping in the vortex core has occurred. Qualitative comparison with contrail photography shows similar features. Finally the distortion and stretching of the plume streamlines inside the vortices can be observed, and the role of the descent of the vortices on the maximum tracer concentration has been discussed. (author) 19 refs.

  11. Modelling wind turbine wakes using the turbulent entrainment hypothesis

    Science.gov (United States)

    Luzzatto-Fegiz, Paolo

    2015-11-01

    Simple models for turbine wakes have been used extensively in the wind energy community, both as independent tools, as well as to complement more refined and computationally-intensive techniques. Jensen (1983; see also Katić et al. 1986) developed a model assuming that the wake radius grows linearly with distance x, approximating the velocity deficit with a top-hat profile. While this model has been widely implemented in the wind energy community, recently Bastankhah & Porté-Agel (2014) showed that it does not conserve momentum. They proposed a momentum-conserving theory, which assumed a Gaussian velocity deficit and retained the linear-spreading assumption, significantly improving agreement with experiments and LES. While the linear spreading assumption facilitates conceptual modeling, it requires empirical estimates of the spreading rate, and does not readily enable generalizations to other turbine designs. Furthermore, field measurements show sub-linear wake growth with x in the far-wake, consistently with results from fundamental turbulence studies. We develop a model by relying on a simple and general turbulence parameterization, namely the entrainment hypothesis, which has been used extensively in other areas of geophysical fluid dynamics. Without assuming similarity, we derive an analytical solution for a circular turbine wake, which predicts a far-wake radius increasing with x 1 / 3, and is consistent with field measurements and fundamental turbulence studies. Finally, we discuss developments accounting for effects of stratification, as well as generalizations to other turbine designs.

  12. Glucocorticoids entrain molecular clock components in human peripheral cells.

    Science.gov (United States)

    Cuesta, Marc; Cermakian, Nicolas; Boivin, Diane B

    2015-04-01

    In humans, shift work induces a desynchronization between the circadian system and the outside world, which contributes to shift work-associated medical disorders. Using a simulated night shift experiment, we previously showed that 3 d of bright light at night fully synchronize the central clock to the inverted sleep schedule, whereas the peripheral clocks located in peripheral blood mononuclear cells (PBMCs) took longer to reset. This underlines the need for testing the effects of synchronizers on both the central and peripheral clocks. Glucocorticoids display circadian rhythms controlled by the central clock and are thought to act as synchronizers of rodent peripheral clocks. In the present study, we tested whether the human central and peripheral clocks were sensitive to exogenous glucocorticoids (Cortef) administered in the late afternoon. We showed that 20 mg Cortef taken orally acutely increased PER1 expression in PBMC peripheral clocks. After 6 d of Cortef administration, the phases of central markers were not affected, whereas those of PER2-3 and BMAL1 expression in PBMCs were shifted by ∼ 9.5-11.5 h. These results demonstrate, for the first time, that human peripheral clocks are entrained by glucocorticoids. Importantly, they suggest innovative interventions for shift workers and jet-lag travelers, combining synchronizing agents for the central and peripheral clocks.

  13. Control aspects of latent heat storage and recovery in concrete

    Energy Technology Data Exchange (ETDEWEB)

    Lee, T.; Hawes, D.W.; Banu, D.; Feldman, D. [Department of Building, Civil and Environmental Engineering, Centre for Building Studies, 1455 de Maisonmeuve Blud. w., Concordia University, Montreal (Canada)

    2000-05-15

    This paper presents the results of macro scale tests that compare the thermal storage performance of ordinary concrete blocks with those that have been impregnated with two phase change materials (PCM). One is a commercial Butyl Stearate (Emerest 2326), and the other is a commercial Paraffin (Unicere 55). The comparative characteristics of these PCM - concrete combinations were examined. Also, the effect of air velocity was studied in respect to the control of the rates of heat storage and discharge. This research is an extension of the laboratory scale work in this area, which were carried out in recent years.

  14. COP Prediction of an ejector refrigeration cycle combined with a vapour compression cycle for automotive air conditioning

    OpenAIRE

    Nat Suvarnakuta; Nutthanun Keerlatiyadatanapat; Thanarath Sriveerakul

    2014-01-01

    This paper presents the COP prediction of an ejector refrigeration cycle combined with a vapour compression cycle for automotive air conditioning. Using computational fluid dynamics (CFD) technique, the performance of an ejector was analyzed in term of the entrainment ratio (Rm) and critical back pressure (CBP). The results from this study were compared with a previous study of combined ejector refrigeration system for automotive air conditioning application [1] which the entrainment ratio (R...

  15. Durability of concrete in saline environment

    OpenAIRE

    1996-01-01

    Contents: - Systematic collection of field data for service life prediction of concrete structures. - Moisture in marine concrete structures - Studies in the BMV-project 1992-1996. - Scaling resistence of concrete field exposure tests. - Chloride induced corrosion in marine concrete structures. - Chloride threshold values in reinforced concrete. - A new method for determing chloride thresholds as a function of potential in field exposure tests. - Estimation of chloride ingress into concrete a...

  16. LiNbO 3 Coating on Concrete Surface: A New and Environmentally Friendly Route for Artificial Photosynthesis

    OpenAIRE

    Nath, Ranjit K.; M. F. M .Zain; Kadhum, Abdul Amir H.

    2013-01-01

    The addition of a photocatalyst to ordinary building materials such as concrete creates environmentally friendly materials by which air pollution or pollution of the surface can be diminished. The use of LiNbO3 photocatalyst in concrete material would be more beneficial since it can produce artificial photosynthesis in concrete. In these research photoassisted solid-gas phases reduction of carbon dioxide (artificial photosynthesis) was performed using a photocatalyst, LiNbO3, coated on concre...

  17. The concrete canister program

    International Nuclear Information System (INIS)

    In the spring of 1974, WNRE began development and demonstration of a dry storage concept, called the concrete canister, as a possible alternative to storage of irradiated CANDU fuel in water pools. The canister is a thick-walled concrete monolith containing baskets of fuel in the dry state. The decay heat from the fuel is dissipated to the environment by natural heat transfer. Four canisters were designed and constructed. Two canisters containing electric heaters have been subjected to heat loads of 2.5 times the design, ramp heat-load cycling, and simulated weathering tests. The other two canisters were loaded with irradiated fuel, one containing fuel bundles of uniform decay heat and the other containing bundles of non-uniform decay heat in a non-symmetrical radial and axial array. The collected data were used to verify the analytical tools for prediction of effectiveness of heat transfer and radiation shielding and to verify the design of the basket and canisters. The demonstration canisters have shown that this concept is a viable alternative to water pools for the storage of irradiated CANDU fuel. (author)

  18. Interface Microstructures in Concrete

    Directory of Open Access Journals (Sweden)

    Puertas, Francisca

    1991-03-01

    Full Text Available This paper constitutes a compilation as well as an interpretation of the present state of knowledge about the different microstructures developed in the interface areas of concrete, that is, the cement paste-aggregates, the cement paste-reinforcement, the cement paste-fiber, etc. The Chemical reactions taking place in interface areas, the development and morphology of such areas and their strength ^since interfaces are taken as the weakest points of concrete are the aspects dealt with in some detail in this work.

    El presente trabajo constituye un resumen y también una interpretación del estado actual del conocimiento respecto de las diferentes microestructuras que se desarrollan en las zonas interfaciales de los hormigones, es decir: pasta de cemento-áridos, pasta de cemento-armaduras, pasta de cemento-fibras, etc. Las reacciones químicas que tienen lugar en la zona interfacial, el desarrollo y morfología de dicha zona y su resistencia (las interfases se consideran como uno de los puntos débiles del hormigón son los aspectos que con cierto detalle se tratan en el trabajo.

  19. Concrete Masonry Designs: Educational Issue.

    Science.gov (United States)

    Hertzberg, Randi, Ed.

    2001-01-01

    This special journal issue addresses concrete masonry in educational facilities construction. The issue's feature articles are: (1) "It Takes a Village To Construct a Massachusetts Middle School," describing a middle school constructed almost entirely of concrete masonry and modeled after a typical small New England village; (2) "Lessons Learned,"…

  20. Radiographic testing in concrete structures

    International Nuclear Information System (INIS)

    The radiographic testing done in concrete structures is used to analyse the homogeneity, position and corrosion of armatures and to detect discontinuity in the concrete such as: gaps, cracks and segregations. This work develops a Image quality Indicator (IQI) with an adequated sensibility to detect discontinuites based on BS4408 norm. (E.G.)

  1. Wood and concrete polymer composites

    International Nuclear Information System (INIS)

    There are several ways to prepare and use wood and concrete polymer composites. The most important improvements in the case of concrete polymer composites are obtained for compressive and tensile strengths. The progress in this field in United States and other countries is discussed in this rview. (M.S.)

  2. Structural lightweight concrete: recent research

    NARCIS (Netherlands)

    Walraven, J.; Den Uijl, J.; Stroband, J.; AI-ZubiN.; Gijsbers, J.; Naaktgeboren, M.

    1995-01-01

    As a result of a number of reasons new interest developed into the use of lightweight aggregate concrete. Within the scope of this development, a modernized code for lightweight concrete had to be written. In order to support this development, a number of research projects have been carried out. The

  3. LASER ABLATION STUDIES OF CONCRETE

    Science.gov (United States)

    Laser ablation was studied as a means of removing radioactive contaminants from the surface and near-surface regions of concrete. We present the results of ablation tests on cement and concrete samples using a 1.6 kW pulsed Nd:YAG laser with fiber optic beam delivery. The laser-s...

  4. Proportioning of light weight concrete

    DEFF Research Database (Denmark)

    Palmus, Lars

    1996-01-01

    Development of a method to determine the proportions of the raw materials in light weight concrete made with leight expanded clay aggregate. The method is based on composite theory......Development of a method to determine the proportions of the raw materials in light weight concrete made with leight expanded clay aggregate. The method is based on composite theory...

  5. Revised Rules for Concrete Bridges

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle; Jensen, F. M.; Middleton, C.;

    This paper is based on research performed for the Highway Agency, London, UK under the project DPU/9/44 "Revision of Bridge Assessment Rules Based on Whole Life Performance: Concrete Bridges" It contains details of a methodology which can be used to generate Whole Life (WL) reliability profiles....... These WL reliability profiles may be used to establish revised rules for Concrete Bridges....

  6. Fatigue of Concrete Armour Units

    DEFF Research Database (Denmark)

    Sørensen, N. B.; Burcharth, H. F.; Liu, Z.

    1995-01-01

    In the present article fatigue as a possible reason for failure of Dolosse armour units made of plain concrete is discussed.......In the present article fatigue as a possible reason for failure of Dolosse armour units made of plain concrete is discussed....

  7. The Concrete and Pavement Challenge

    Science.gov (United States)

    Roman, Harry T.

    2012-01-01

    The modern world is characterized by the extensive use of concrete and asphalt pavement. Periodically, these materials are replaced and the old materials disposed of. In this challenge, students will be asked to develop ways to reuse the old materials. It is important for students to understand how concrete and asphalt are made and applied, as…

  8. Turbulent flow field and air entrainment in laboratory plunging breaking waves

    Science.gov (United States)

    Na, Byoungjoon; Chang, Kuang-An; Huang, Zhi-Cheng; Lim, Ho-Joon

    2016-05-01

    This paper presents laboratory measurements of turbulent flow fields and void fraction in deep-water plunging breaking waves using imaging and optical fiber techniques. Bubble-size distributions are also determined based on combined measurements of velocity and bubble residence time. The most excited mode of the local intermittency measure of the turbulent flow and its corresponding length scale are obtained using a wavelet-based method and found to correlate with the swirling strength and vorticity. Concentrated vortical structures with high intermittency are observed near the lower boundaries of the aerated rollers where the velocity shear is high; the length scale of the deduced eddies ranges from 0.05 to 0.15 times the wave height. The number of bubbles with a chord length less than 2 mm demonstrates good correlation with the swirling strength. The power-law scaling and the Hinze scale of the bubbles determined from the bubble chord length distribution compare favorably with existing measurements. The turbulent dissipation rate, accounting for void fraction, is estimated using mixture theory. When void fraction is not considered, the turbulent dissipation rate is underestimated by more than 70% in the initial impinging and the first splash-up roller. A significant discrepancy of approximately 67% between the total energy dissipation rate and the turbulence dissipation rate is found. Of this uncounted dissipation, 23% is caused by bubble-induced dissipation.

  9. Experimental investigation on the droplet entrainment from interfacial waves in air-water horizontal stratified flow

    International Nuclear Information System (INIS)

    The main purpose of the wire is to avoid collision between adjacent rods.. Furthermore, a vortex induced vibration can be mitigated by wire spacers. In this study, the RANS based CFD methodology using an innovative grid generation has been evaluated in the 7-pin, 37-pin, and 217-pin wire wrapped fuel assembly, which is using the general purpose commercial CFD code, CFX. The RANS-based CFD methodology using the innovative hexagonal grid generation with the in-house code and the GGI function of the CFX code has been evaluated in the 7-pin, 37-pin, and 217-pin wire wrapped fuel assembly. SFR (Sodium-cooled Fast Reactor) system is one of the nuclear reactors in which a recycling of transuranics (TRUs) by reusing spent nuclear fuel sustains the fission chain reaction. This situation strongly motivated Korea Atomic Energy Research Institute (KAERI) to start a Prototype Gen Sodium-cooled Fast Reactor (PGSFR) design project under the national nuclear R and D program. Generally, SFR system has tight package of the fuel bundle and the high power density. The fuel assembly of SFR system is consisted of wire wrapped fuel bundles with triangular loose array. The bundles of the SFR fuel assembly usually consisted of rods and wire spacers. The innovative RANS-based CFD methodology can remarkably reduce the number of meshes. Grid sensitivity study of the wall y grid scale with SST turbulence model in 7-pin fuel assembly has been carried out, and the uncertainty of friction factor was under the 6.0%. It has been validated that the GGI function of CFX code is very conservative interpolation function. The innovative RANS based CFD methodology can be successfully extended to real 217- pin wire-wrapped fuel assembly of KAERI 2014 PGSFR

  10. Shear reinforced beams in autoclaved aerated concrete

    DEFF Research Database (Denmark)

    Cornelius, Thomas

    2010-01-01

    Shear behaviour in concrete materials is very well documented, for normal density concrete materials. In this paper results of various tests on low density concrete materials like aerated autoclaved concrete (in the following denoted aircrete) will be presented and analyzed for different combinat......Shear behaviour in concrete materials is very well documented, for normal density concrete materials. In this paper results of various tests on low density concrete materials like aerated autoclaved concrete (in the following denoted aircrete) will be presented and analyzed for different...

  11. Miniature Sample Collection and Delivery System using Gas-Entrained Powder Transport Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to develop a miniature system for acquisition and delivery of solid samples to landed planetary instruments. This system would entrain powder produced by...

  12. Dependence of entrainment in shallow cumulus convection on vertical velocity and distance to cloud edge

    Science.gov (United States)

    Tian, Yang; Kuang, Zhiming

    2016-04-01

    The dependence of entrainment rate on environmental conditions and cloud characteristics is investigated using large eddy simulations (LES) of the response of shallow cumulus convection to a small-amplitude temperature perturbation that is horizontally uniform and localized in height. The simulated cumulus fields are analyzed in the framework of an ensemble of entraining plumes by tracking a large number of Lagrangian parcels embedded in the LES and grouping them into different plumes based on their detrainment heights. The results show that fractional entrainment rate per unit height of a plume is inversely proportional to the plume's vertical velocity and its distance to the cloud edge, while changes in environmental stratification and relative humidity, the plume's buoyancy, or the vertical gradient of its buoyancy due to the temperature perturbation have little effect on the plume's entrainment rate.

  13. Basic principles of concrete structures

    CERN Document Server

    Gu, Xianglin; Zhou, Yong

    2016-01-01

    Based on the latest version of designing codes both for buildings and bridges (GB50010-2010 and JTG D62-2004), this book starts from steel and concrete materials, whose properties are very important to the mechanical behavior of concrete structural members. Step by step, analysis of reinforced and prestressed concrete members under basic loading types (tension, compression, flexure, shearing and torsion) and environmental actions are introduced. The characteristic of the book that distinguishes it from other textbooks on concrete structures is that more emphasis has been laid on the basic theories of reinforced concrete and the application of the basic theories in design of new structures and analysis of existing structures. Examples and problems in each chapter are carefully designed to cover every important knowledge point. As a basic course for undergraduates majoring in civil engineering, this course is different from either the previously learnt mechanics courses or the design courses to be learnt. Compa...

  14. Study on healthcare magnetic concrete

    Institute of Scientific and Technical Information of China (English)

    YANG Yushan; DONG Faqin; FENG Jianjun

    2006-01-01

    Magnetic concrete was prepared by adding SrFe12O9 magnetic functional elementary material into concrete, and its magnetism was charged by magnetizing machine. The effect of SrFe12O9 content on magnetic field intensity and the attenuation of magnetic field intensity were investigated in different medium. The blood viscosity of rats kept in magnetic concrete was carried out. The results show that magnetic concrete can be prepared by adding SrFe12O9, and magnetic fields intensity increases with the augment of ferrite content. The attenuation of magnetic fields is mainly related with the density of medium, but it is secondary to the properties of medium. The blood viscosity of rats decreases under magnetic condition, but the blood cells remain the same as before. Experimental results support that magnetic concrete has great healthcare function.

  15. Novel techniques for concrete curing

    DEFF Research Database (Denmark)

    Kovler, Konstantin; Jensen, Ole Mejlhede

    2005-01-01

    It is known that some high-strength/high-performance concretes (HSC/HPC) are prone to cracking at an early age unless special precautions are taken. The paper deals with the methods of curing as one of the main strategies to ensure good performance of concrete. Curing by both external (conventional......) and internal methods is reviewed and analyzed, among other methods of mitigating shrinkage and cracking of concrete. The focus is on the mitigation of autogenous shrinkage of low water to binder ratio (w/b) concrete by means of internal curing. The concepts of internal curing are based on using lightweight...... aggregate, superabsorbent polymers or water-soluble chemicals, which reduce water evaporation (so called "internal sealing"). These concepts have been intensively researched in the 90s, but still are not widespread among contractors and concrete suppliers. The differences between conventional methods...

  16. Neural entrainment to rhythmically-presented auditory, visual and audio-visual speech in children

    Directory of Open Access Journals (Sweden)

    Alan James Power

    2012-07-01

    Full Text Available Auditory cortical oscillations have been proposed to play an important role in speech perception. It is suggested that the brain may take temporal ‘samples’ of information from the speech stream at different rates, phase-resetting ongoing oscillations so that they are aligned with similar frequency bands in the input (‘phase locking’. Information from these frequency bands is then bound together for speech perception. To date, there are no explorations of neural phase-locking and entrainment to speech input in children. However, it is clear from studies of language acquisition that infants use both visual speech information and auditory speech information in learning. In order to study neural entrainment to speech in typically-developing children, we use a rhythmic entrainment paradigm (underlying 2 Hz or delta rate based on repetition of the syllable ba, presented in either the auditory modality alone, the visual modality alone, or as auditory-visual speech (via a talking head. To ensure attention to the task, children aged 13 years were asked to press a button as fast as possible when the ba stimulus violated the rhythm for each stream type. Rhythmic violation depended on delaying the occurrence of a ba in the isochronous stream. Neural entrainment was demonstrated for all stream types, and individual differences in standardized measures of language processing were related to auditory entrainment at the theta rate. Further, there was significant modulation of the preferred phase of auditory entrainment in the theta band when visual speech cues were present, indicating cross-modal phase resetting. The rhythmic entrainment paradigm developed here offers a method for exploring individual differences in oscillatory phase locking during development. In particular, a method for assessing neural entrainment and cross-modal phase resetting would be useful for exploring developmental learning difficulties thought to involve temporal sampling

  17. Rev-erbα in the brain is essential for circadian food entrainment

    OpenAIRE

    Julien Delezie; Stéphanie Dumont; Cristina Sandu; Sophie Reibel; Paul Pevet; Etienne Challet

    2016-01-01

    Foraging is costly in terms of time and energy. An endogenous food-entrainable system allows anticipation of predictable changes of food resources in nature. Yet the molecular mechanism that controls food anticipation in mammals remains elusive. Here we report that deletion of the clock component Rev-erbα impairs food entrainment in mice. Rev-erbα global knockout (GKO) mice subjected to restricted feeding showed reduced elevations of locomotor activity and body temperature prior to mealtime, ...

  18. Comparative study of the shield of concrete blocks with hematite in relation to common concrete blocks; Avaliacao comparativa entre as propriedades de atenuacao de blocos de concreto com hematita e blocos de concreto convencional

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Paulo R.; Buerger, Andre A., E-mail: pcosta@if.usp.br [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Inst. de Fisica. Lab. de Dosimetria; Naccache, Veronica K.; Priszkulnik, Simao [Universidade Mackenzie, Sao Paulo, SP (Brazil). Departamento de Engenharia

    2012-08-15

    The present work shows results of an empirical evaluation of the transmission properties of two radioprotection materials: an ordinary concrete and an ordinary concrete mixed with hematite. It was used techniques of x-ray spectroscopy and measurements of the air-kerma transmitted through these two materials in order to compare the transmission properties for each one. (author)

  19. Design formula of reinforced concrete structures against rigid missile impact

    Energy Technology Data Exchange (ETDEWEB)

    Ito, Chihiro; Shirai, Koji; Ohnuma, Hiroshi [Central Research Inst. of Electric Power Industry, Abiko, Chiba (Japan). Abiko Research Lab.

    1995-01-01

    For the design of concrete containment structures built in nuclear power stations in Japan, internal pressure, temperature load and earthquake load have so far been considered as the major types of load that could result from accident. In some foreign countries, impact load caused by collision of missile is taken into consideration for the design of this kind of structures as well. Also in Japan, in the design of the repossessing plants which is now under construction at Shimokita area, air craft crash is taken into account. In this study, in order to establish the design method of concrete structures against impact due to collision of missile, the impact tests have been carried out using hard missile with the velocity from 4.0m/s to 250m/s. Based on these results, we proposed the design method of reinforced concrete structure against the collision of hard missile. (author).

  20. Are non-human primates capable of rhythmic entrainment? Evidence for the gradual audiomotor evolution hypothesis.

    Science.gov (United States)

    Merchant, Hugo; Honing, Henkjan

    2013-01-01

    We propose a decomposition of the neurocognitive mechanisms that might underlie interval-based timing and rhythmic entrainment. Next to reviewing the concepts central to the definition of rhythmic entrainment, we discuss recent studies that suggest rhythmic entrainment to be specific to humans and a selected group of bird species, but, surprisingly, is not obvious in non-human primates. On the basis of these studies we propose the gradual audiomotor evolution hypothesis that suggests that humans fully share interval-based timing with other primates, but only partially share the ability of rhythmic entrainment (or beat-based timing). This hypothesis accommodates the fact that non-human primates (i.e., macaques) performance is comparable to humans in single interval tasks (such as interval reproduction, categorization, and interception), but show differences in multiple interval tasks (such as rhythmic entrainment, synchronization, and continuation). Furthermore, it is in line with the observation that macaques can, apparently, synchronize in the visual domain, but show less sensitivity in the auditory domain. And finally, while macaques are sensitive to interval-based timing and rhythmic grouping, the absence of a strong coupling between the auditory and motor system of non-human primates might be the reason why macaques cannot rhythmically entrain in the way humans do.

  1. The role of the endocrine system in feeding-induced tissue-specific circadian entrainment.

    Science.gov (United States)

    Sato, Miho; Murakami, Mariko; Node, Koichi; Matsumura, Ritsuko; Akashi, Makoto

    2014-07-24

    The circadian clock is entrained to environmental cycles by external cue-mediated phase adjustment. Although the light input pathway has been well defined, the mechanism of feeding-induced phase resetting remains unclear. The tissue-specific sensitivity of peripheral entrainment to feeding suggests the involvement of multiple pathways, including humoral and neuronal signals. Previous in vitro studies with cultured cells indicate that endocrine factors may function as entrainment cues for peripheral clocks. However, blood-borne factors that are well characterized in actual feeding-induced resetting have yet to be identified. Here, we report that insulin may be involved in feeding-induced tissue-type-dependent entrainment in vivo. In ex vivo culture experiments, insulin-induced phase shift in peripheral clocks was dependent on tissue type, which was consistent with tissue-specific insulin sensitivity, and peripheral entrainment in insulin-sensitive tissues involved PI3K- and MAPK-mediated signaling pathways. These results suggest that insulin may be an immediate early factor in feeding-mediated tissue-specific entrainment.

  2. High performance polymer concrete

    Directory of Open Access Journals (Sweden)

    Frías, M.

    2007-06-01

    Full Text Available This paper studies the performance of concrete whose chief components are natural aggregate and an organic binder —a thermosetting polyester resin— denominated polymer concrete or PC. The material was examined macro- and microscopically and its basic physical and mechanical properties were determined using mercury porosimetry, scanning electron microscopy (SEM-EDAX, X-ray diffraction (XRD and strength tests (modulus of elasticity, stress-strain curves and ultimate strengths. According to the results of these experimental studies, the PC exhibited a low density (4.8%, closed pore system and a concomitantly continuous internal microstructure. This would at least partially explain its mechanical out-performance of traditional concrete, with average compressive and flexural strength values of 100 MPa and over 20 MPa, respectively. In the absence of standard criteria, the bending test was found to be a useful supplement to compressive strength tests for establishing PC strength classes.Este trabajo de investigación aborda el estudio de un hormigón de altas prestaciones, formado por áridos naturales y un aglomerante orgánico constituido por una resina termoestable poliéster, denominado hormigón polimérico HP. Se describe el material a nivel microscópico y macroscópico, presentando sus propiedades físicas y mecánicas fundamentales, mediante diferentes técnicas experimentales, tales como: porosimetría de mercurio, microscopía electrónica (SEM-EDAX, difracción de rayos X (DRX y ensayos mecánicos (módulo de elasticidad, curvas tensión- deformación y resistencias últimas. Como consecuencia del estudio experimental llevado a cabo, se ha podido apreciar cómo el HP está formado por porosidad cerrada del 4,8%, proporcionando una elevada continuidad a su microestructura interna, lo que justifica, en parte, la mejora de propiedades mecánicas respecto al hormigón tradicional, con unos valores medios de resistencia a compresión de 100

  3. How to transform an asphalt concrete pavement into a solar turbine

    International Nuclear Information System (INIS)

    Highlights: • We create a system for harvesting energy from asphalt concrete. • We create an artificial porosity in the asphalt concrete. • We connect a chimney to this porosity. • Differences in temperature produce an air flow. • This air flow serves also for cooling down the pavement. - Abstract: Asphalt concrete can absorb a considerable amount of the incident solar radiation. For this reason asphalt roads could be used as solar collectors. There have been different attempts to achieve this goal. All of them have been done by integrating pipes conducting liquid, through the structure of the asphalt concrete. The problem of this system is that all pipes need to be interconnected: if one is broken, the liquid will come out and damage the asphalt concrete. To overcome these limitations, in this article, an alternative concept is proposed:parallel air conduits, where air can circulate will be integrated in the pavement structure. The idea is to connect these artificial pore volumes in the pavement to an updraft or to a downdraft chimney. Differences of temperature between the pavement and the environment can be used to create an air flow, which would allow wind turbines to produce an amount of energy and that would cool the pavement down in summer or even warm it up in winter. To demonstrate that this is possible, an asphalt concrete prototype has been created and basics calculations on the parameters affecting the system have been done. It has been found that different temperatures, volumes of air inside the asphalt and the difference of temperature between the asphalt concrete and the environment are critical to maximize the air flow through the pavement. Moreover, it has been found that this system can be also used to reduce the heat island effect

  4. Effect of oxy-fuel combustion with steam addition on coal ignition and burnout in an entrained flow reactor

    International Nuclear Information System (INIS)

    The ignition temperature and burnout of a semi-anthracite and a high-volatile bituminous coal were studied under oxy-fuel combustion conditions in an entrained flow reactor (EFR). The results obtained under oxy-fuel atmospheres (21%O2-79%CO2, 30%O2-70% O2 and 35%O2-65%CO2) were compared with those attained in air. The replacement of CO2 by 5, 10 and 20% of steam in the oxy-fuel combustion atmospheres was also evaluated in order to study the wet recirculation of flue gas. For the 21%O2-79%CO2 atmosphere, the results indicated that the ignition temperature was higher and the coal burnout was lower than in air. However, when the O2 concentration was increased to 30 and 35% in the oxy-fuel combustion atmosphere, the ignition temperature was lower and coal burnout was improved in comparison with air conditions. On the other hand, an increase in ignition temperature and a worsening of the coal burnout was observed when steam was added to the oxy-fuel combustion atmospheres though no relevant differences between the different steam concentrations were detected. -- Highlights: → The ignition temperature and the burnout of two thermal coals under oxy-fuel combustion conditions were determined. → The effect of the wet recirculation of flue gas on combustion behaviour was evaluated. → Addition of steam caused a worsening of the ignition temperature and coal burnout.

  5. Environmental Impact Analysis of Acidification and Eutrophication Due to Emissions from the Production of Concrete

    Directory of Open Access Journals (Sweden)

    Tae Hyoung Kim

    2016-06-01

    Full Text Available Concrete is a major material used in the construction industry that emits a large amount of substances with environmental impacts during its life cycle. Accordingly, technologies for the reduction in and assessment of the environmental impact of concrete from the perspective of a life cycle assessment (LCA must be developed. At present, the studies on LCA in relation to greenhouse gas emission from concrete are being carried out globally as a countermeasure against climate change. However, the studies on the impact of the substances emitted in the concrete production process on acidification and eutrophication are insufficient. As such, assessing only a single category of environmental impact may cause a misunderstanding about the environmental friendliness of concrete. The substances emitted in the concrete production process have an impact not only on global warming but also on acidification and eutrophication. Acidification and eutrophication are the main causes of air pollution, forest destruction, red tide phenomena, and deterioration of reinforced concrete structures. For this reason, the main substances among those emitted in the concrete production process that have an impact on acidification and eutrophication were deduced. In addition, an LCA technique through which to determine the major emissions from concrete was proposed and a case analysis was carried out. The substances among those emitted in the concrete production process that are related to eutrophication were deduced to be NOx, NH3, NH4+, COD, NO3−, and PO43−. The substances among those emitted in the concrete production process that are related to acidification, were found to be NOx, SO2, H2S, and H2SO4. The materials and energy sources among those input into the concrete production process, which have the biggest impact on acidification and eutrophication, were found to be coarse aggregate and fine aggregate.

  6. Effects of composition and exposure on the solar reflectance of Portland cement concrete

    Energy Technology Data Exchange (ETDEWEB)

    Levinson, Ronnen; Akbari, Hashem

    2001-12-21

    Increasing the solar reflectance (albedo) of a paved surface keeps it cooler in the sun, reducing convection of heat from pavement to air and thereby decreasing the ambient air temperature. Simulations of the influence of pavement albedo on air temperature in Los Angeles predict that increasing the albedo of 1,250 km2 of pavement by 0.25 would save cooling energy worth $15M yr-1, and reduce smog-related medical and lost-work expenses by $76M yr-1. Most sidewalks and a small fraction of roads and parking areas are paved with portland cement concrete, which can be made quite reflective through suitable choice of cement and aggregate. Variations with composition and environmental exposure of the albedos of portland cement concrete pavements were investigated through laboratory fabrication and exposure of 32 mixes of concrete. Twenty-four mixes yielded substandard, ''rough'' concretes due to high, unmet aggregate water demand. The albedos of the remaining eight ''smooth'' concrete mixes ranged from 0.41 to 0.77 (mean 0.59). Simulated weathering, soiling, and abrasion each reduced average concrete albedo (mean decreases 0.06, 0.05, and 0.19, respectively), though some samples became slightly more reflective through weathering or soiling. Simulated rain (wetting) strongly depressed the albedos of concretes (mean decrease 0.23) until their surfaces were dried. Concrete albedo grew as the cement hydration reaction progressed (mean increase 0.08), but stabilized within six weeks of casting. White-cement concretes were on average significantly more reflective than gray-cement concretes. The albedo of the most-reflective white-cement concrete was 0.18 to 0.39 higher than that of the most-reflective gray-cement concrete, depending on state of exposure. Concrete albedo generally correlated with cement albedo and sand albedo, and, after abrasion, with rock albedo. Cement albedo had a disproportionately strong influence on the reflectance

  7. A state-of-the-art report on modelling of liquid entrainment phenomena in two-phase flow

    International Nuclear Information System (INIS)

    Since the interfacial area density of liquid droplet flow is extremely higher than that of general two-phase flows (bubbly, slug, churn, or annular flow), characteristics of interfacial mass, momentum, and heat transfers are also quite different. In this work the modelling of liquid droplet entrainment phenomena is investigated, which is divided into onset of droplet entrainment, droplet size, entrainment amount, and entrainment rate models. The droplet entrainment models of RELAP5/MOD3 and CATHARE2 codes are also covered in this work. Both of the codes use the two-fluid model for two-phase flow. Therefore the entrained droplet and continuous liquid phase are not distinguished from each other by fluid-field equations. But, they are differently simulated by so-called flow regime map. In case of two-fluid model, droplet can exist in annular-mist flow, mist flow, inverted annular-mist flow regimes, etc. In this case, onset of liquid droplet is used as one of the flow-regime transition criteria, and the 'entrainment amount' models to predict the amount of liquid phase that exists as droplet form. Recently three-or four-field models have been developed where the entrained droplet is modelled by a set of field equations. These models use the 'entrainment rate' model as a source term in the mass conservation equation. The last section of this report describes 'liquid entrainment' and 'vapor pull-through' models for horizontal T-junctions. 5 tabs., 40 figs., 47 refs. (Author)

  8. 季节冻土区盐渍土环境下混凝土抗冻耐久性机理%Frost Resistance and Durability Mechanism of Concrete Under Saline-Alkali Condition in Seasonal Frozen Soil Area

    Institute of Scientific and Technical Information of China (English)

    宿晓萍; 王清; 王文华; 孙昊月

    2014-01-01

    In order to study the frost resistance and durability of concrete structures under double factors of salts attack and freezing-thawing cycles in seasonal frozen soil area,multi-salt solution with three kinds of mass fraction and water were prepared according to the type and quantity of the main dissolved salts in the spring soil of Daan region.Specimens of ordinary concrete with different mixture ratios,two kinds of air-entraining concrete and two kinds of fly-ash concrete were prepared for the multiple salts and freezing-thawing cycle tests.The mass loss,dynamic elastic modulus reduction and microstructure of tested samples were analyzed.Results showed that concrete erosion was aggravated by multi-salt under the action of freezing-thawing cycles.The degree of frozen damage was related to the mass fraction of salt solution,times of freezing-thawing cycle,air content in concrete and fly-ash addition ratio.Reasons that lead salt-frozen damage occur were expansion pressure produced during the course of water turning into ice,the seepage pressure of ice and water and the chemical erosion and crystalline swelling of salt from the reaction between multi-salt and cement hydration production,among which salt crystallization played more important role in the damage of concrete internal structure.%为了研究混凝土在冻融交替与盐类侵蚀双重因素作用下的抗冻耐久性能,根据季节冻土区大安境内盐渍土中主要易溶盐的类型与含量,配制了3种质量分数的复合盐侵蚀溶液,制备了普通混凝土、2种引气混凝土及2组粉煤灰混凝土试件,进行盐蚀快速冻融循环试验,对盐冻破坏后混凝土的质量损失、动弹性模量衰减及其微观结构进行分析。试验结果表明:在冻融循环作用下,复合盐加剧了混凝土的冻融剥蚀破坏;混凝土的冻害程度与侵蚀盐溶液的质量分数、冻融循环次数、混凝土的含气量、粉煤灰掺量等因素有关;造

  9. Porosity of Concrete - Morphological Study of Model Concrete

    NARCIS (Netherlands)

    Hu, J.

    2004-01-01

    This study has developed a comprehensive methodological framework for characterizing geometrical and morphological aspects of pore space in cementitious materials and explored its application to actual cement pastes and model concretes for the purpose of predicting mechanical and transport propertie

  10. Self-compacting concrete (SCC)

    DEFF Research Database (Denmark)

    Geiker, Mette Rica

    2008-01-01

    In many aspects Self-Compacting Concrete (SCC, “Self-Consolidating Concrete” in North America) can be considered the concrete of the future. SCC is a family of tailored concretes with special engineered properties in the fresh state. SCC flows into the formwork and around even complicated...... freedom in structural design. The present Chapter describes selected properties of SCC. The properties and use of SCC are illustrated through a few case histories and future trends are briefly described. The Chapter concludes with a list of sources of further information....

  11. Explosive demolition of activated concrete

    International Nuclear Information System (INIS)

    This paper describes the removal of a radiologically contaminated concrete pad. This pad was removed during 1979 by operating personnel under the direction of the Waste Management Program of EG and G Idaho, Inc. The concrete pad was the foundation for the Organic Moderated Reactor Experiment (OMRE) reactor vessel located at the Idaho National Engineering Laboratory (INEL). The pad consisted of a cylindrical concrete slab 15 ft in diameter, 2 ft thick, and reinforced with steel bar. It was poured directly onto basalt rocks approximately 20 ft below grade. The entire pad contained induced radioactivity and was therefore demolished, boxed, and buried rather than being decontaminated. The pad was demolished by explosive blasting

  12. PCM Concrete. [Phase Change Materials

    Energy Technology Data Exchange (ETDEWEB)

    Juul Andersen, T. [Danish Technological Institute, Taastrup (Denmark); Poulsen, H.-H. [BASF A/S, Roedekro (Denmark); Passov, F. [Spaencom A/S, Hedehusene (Denmark); Heiselberg, P. [Aalborg Univ..Aalborg (Denmark)

    2013-04-01

    PCM-Concrete was a research and development project launched in 2009 and finished in 2012. The project, which was funded by The Danish National Advanced Technology Foundation, had a total budget of 1.7 million Euros and included 4 partners: Danish Technological Institute (project manager), Aalborg University, BASF A/S and Spaencom A/S. The overall vision of the project was to reduce energy consumption for heating and cooling in buildings by developing high-performance concrete structures microencapsulated Phase Change Materials (PCM). The PCM used in the project was Micronal produced by BASF A/S. Micronal is small capsules with an acrylic shell and inside a wax with a melting point at approx. 23 deg. C equal to a comfortable indoor temperature. During the melting process thermal energy is transferred to chemical reaction (melting/solidification) depending on PCM being heated up or cooled down. Adding Micronal to concrete would theoretically increase the thermal mass of the concrete and improve the diurnal heat capacity which is the amount of energy that can be stored and released during 24 hours. Nevertheless, it is a relatively new technology that has not received much attention, yet. In the PCM-Concrete project 5 main investigations were carried out: 1) Development of concrete mix design with PCM. 2) Investigation of thermal properties of the PCM concrete: thermal conductivity, specific heat capacity, density. 3) Up-scaling the research to industrial production of PCM-concrete structures. 4) Testing energy efficiency in full scale. 5) Confronting aesthetic and acoustic barriers to full exploitation of the potential of PCM-concrete structures. The results from the test program showed: 1) That the diurnal heat storage capacity is higher for all 4 hollow core decks with tiles attached compared to the reference hollow core deck. 2) The hollow core decks with concrete tiles without PCM performs slightly better than the tiles with PCM. 3) That is was impossible to

  13. Energy efficiency program through exchange of air conditioners in residential sector of Manaus city: a concrete experience; Programa de eficiencia energetica atraves da troca de condicionadores de ar no setor residencial de Manaus: uma experiencia concreta

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Fabricio Rodrigues; Goncalves, Ana Catarina Lima Chaves; Cartaxo, Elizabeth Ferreira; Gomes, Hugo Miguel Oliveira; Nascimento, Nilton Correa; Inui, Raul Eiji; Guedes, Ricardo Augusto de Morais; Benchaya, Roberto Tavares [Universidade Federal do Amazonas (UFAM), Manaus, AM (Brazil)

    2004-07-01

    The present review attempts to evaluate the importance of efficient equipment diffusion in reducing energy consumption, based upon the Study-case of an air conditioned exchange program in Manaus city of Amazonas. In spite of the existence, in the actual market, of efficient technology, it has been, yet, badly diffused, mostly due to economical and informative laps. Therefore, once tried to demonstrate the potential benefits, in technical gains, of energy efficiency offered by efficient Air conditioned equipment, through a plan that favors the consumer's participation as an active contributor in the dissemination process of efficient technology, and a following program for efficiency evaluation, beside a tributary evaluation proposal, so that technology becomes accessible to the general population, attempting its benefices. In addition, the environmental benefits of that specific proposal are analyzed, trough the developed recycling program. (author)

  14. Modeling of concrete carbonation in deep geological disposal of intermediate level waste

    International Nuclear Information System (INIS)

    Simulations of atmospheric carbonation of Intermediate-Level Long-lived radioactive Waste (ILLW) concrete packages were conducted to evaluate their possible chemical degradations. Two-phase liquid water-air flow is combined with gas component diffusion processes leading to a progressive drying of the concrete.Complete drying of the 11 cm thick waste disposal package wall occurs over a period ranging from 2 years for the low-performance concrete to 10 years for the high-performance concrete. The drying process slows down when transport characteristics of concretes are enhanced. Carbonation depths in the order of 2 to 3 cm in 100 years are predicted for this cementitious component. However, these values are slightly overestimated compared to experimental data. Also the kinetic model of mineral reactivity requires improvements with respect to the protective effect of secondary carbonates and to thermodynamic data. (authors)

  15. Modeling of concrete carbonation in deep geological disposal of intermediate level waste

    Directory of Open Access Journals (Sweden)

    Poyet S.

    2013-07-01

    Full Text Available Simulations of atmospheric carbonation of Intermediate-Level Long-lived radioactive Waste (ILLW concrete packages were conducted to evaluate their possible chemical degradations. Two-phase liquid water-air flow is combined with gas component diffusion processes leading to a progressive drying of the concrete.Complete drying of the 11 cm thick waste disposal package wall occurs over a period ranging from 2 years for the low-performance concrete to 10 years for the high-performance concrete. The drying process slows down when transport characteristics of concretes are enhanced. Carbonation depths in the order of 2 to 3 cm in 100 years are predicted for this cementitious component. However, these values are slightly overestimated compared to experimental data. Also the kinetic model of mineral reactivity requires improvements with respect to the protective effect of secondary carbonates and to thermodynamic data.

  16. Review of concrete properties for prestressed concrete pressure vesssels

    International Nuclear Information System (INIS)

    The desire for increasing power output along with safety requirements has resulted in consideration of the prestressed concrete pressure vessel (PCPV) for most current nuclear reactor systems, as well as for the very-high-temperature reactor for process heat and as primary pressure vessels for coal conversion systems. Results are presented of a literature review to ascertain current knowledge regarding plain concrete properties under conditions imposed by a mass concrete structure such as PCRV. The effects of high temperature on such properties as strength, elasticity, and creep are discussed, as well as changes in thermal properties, multiaxial behavior, and the mechanisms thought to be responsible for the observed behavior. In addition, the effects of radiation and moisture migration are discussed. It is concluded that testing results found in the technical literature show much disagreement as to the effects of temperature on concrete properties. The variations in concrete mixtures, curing and testing procedures, age at loading, and moisture conditions during exposure and testing are some of the reasons for such disagreement. Test results must be limited, in most cases, to the materials and conditions of a given test rather than applied to such a general class of materials such as concrete. It is also concluded that sustained exposure of normal concretes to current PCRV operating conditions will not result in any significant loss of properties. However, lack of knowledge regarding effects of temperatures exceeding 1000C (2120F), moisture migration, and multiaxial behavior precludes a statement advocating operation beyond current design limits. The report includes recommendations for future research on concrete for PCPVs

  17. Concrete ice abrasion rig and wear measurements

    NARCIS (Netherlands)

    Shamsutdinova, G.; Rike, P.B.; Hendriks, M.A.N.; Jacobsen, S.

    2015-01-01

    The wear of concrete material due to ice movement is a challenge for offshore and coastal structures. Concrete surfaces exposed to moving ice are subjected to wear at various rates depending on concrete and ice properties. At NTNU, Department of Structural Engineering, concrete ice abrasion phenomen

  18. Monitoring water loss form fresh concrete

    DEFF Research Database (Denmark)

    Jensen, Ole Mejlhede

    2006-01-01

    Desiccation of concrete before or during setting may lead to detrimental plastic shrinkage cracking in the concrete surface zone. Cracking due to plastic shrinkage is a major technological problem for any concrete, however, modern high-performance concretes are especially susceptible to this...

  19. Entrained Flow Black Liquor Gasification - Detailed Experiments and Mathematical Modelling

    Energy Technology Data Exchange (ETDEWEB)

    Carlsson, Per (Energy Technology Centre, Piteaa (Sweden)), e-mail: per.carlsson@etcpitea.se

    2009-07-01

    Black liquor, a by-product from the Kraft pulping process is a highly viscous fluid consisting of approximately 30% water, 30 % alkali salts and 40 % combustible material. The alkali salts originating from the pulp making process need to be recovered in order for the pulp mill to be economical and to satisfy environmental regulation. Currently, the recovery takes place in large boilers called Tomlinson recovery boilers. However, a more energy efficient way to recover the chemicals could be via gasification in a pressurized, entrained flow, high temperature gasifier. To demonstrate this technology a development plant (DP1) was built in 2005 by the technology vendor Chemrec. Since then, the plant has been running for more than 10,000 h and frequently been updated and optimized. As steps towards commercialization and scale-up different computational models of varying sophistication are used as design and optimization tools for the process. Still, the engineering tools can only provide sensible predictions if they are properly validated and verified. This thesis is concerned with validation of a comprehensive mathematical model based on Computational Fluid Dynamics (CFD) describing the gasification reactor and experimental investigations of the process characteristics in the DP1 gasifier. Paper A describes the system design and methodology for high temperature gas sampling during pressurized black liquor gasification. In this work a water-cooled gas sampling probe is installed in the hot part of the DP1 gasification reactor and several gas samples are withdrawn and analyzed. The experimentally obtained data in Paper A are then used as validation data for the CFD-model described in Paper B. In Paper C the obtained data from Paper A are thoroughly analyzed and the influence of reactor operation on producer gas composition is determined. In Paper D black liquor sprays from a gas assisted nozzle is experimentally investigated using high speed photography. Furthermore, the

  20. Concrete density estimation by rebound hammer method

    Energy Technology Data Exchange (ETDEWEB)

    Ismail, Mohamad Pauzi bin, E-mail: pauzi@nm.gov.my; Masenwat, Noor Azreen bin; Sani, Suhairy bin; Mohd, Shukri [NDT Group, Nuclear Malaysia, Bangi, Kajang, Selangor (Malaysia); Jefri, Muhamad Hafizie Bin; Abdullah, Mahadzir Bin [Material Technology Program, Faculty of Applied Sciences, UiTM, Shah Alam, Selangor (Malaysia); Isa, Nasharuddin bin; Mahmud, Mohamad Haniza bin [Pusat Penyelidikan Mineral, Jabatan Mineral dan Geosains, Ipoh, Perak (Malaysia)

    2016-01-22

    Concrete is the most common and cheap material for radiation shielding. Compressive strength is the main parameter checked for determining concrete quality. However, for shielding purposes density is the parameter that needs to be considered. X- and -gamma radiations are effectively absorbed by a material with high atomic number and high density such as concrete. The high strength normally implies to higher density in concrete but this is not always true. This paper explains and discusses the correlation between rebound hammer testing and density for concrete containing hematite aggregates. A comparison is also made with normal concrete i.e. concrete containing crushed granite.

  1. Tests on standard concrete samples

    CERN Multimedia

    CERN PhotoLab

    1973-01-01

    Compression and tensile tests on standard concrete samples. The use of centrifugal force in tensile testing has been developed by the SB Division and the instruments were built in the Central workshops.

  2. Nondestructive testing of concrete structures

    International Nuclear Information System (INIS)

    Nondestructive testing of concrete is highly inhomogeneous which makes it cumbersome to setup experimental procedures and analyze experimental data. However, recent research and development activities have discovered the different methods of NDT, like the electromagnetic method, ultrasonic pulse velocity test, pulse echo/impact echo test, infrared thermography, radar or short pulse radar techniques, neutron and gamma radiometry, radiography, carbonation test and half-cell potential method available for NDT of concrete structures. NDT of concrete is emerging as a useful tool for quality control and assurance. This papers also describes the more common NDT methods discussed during the two-week course on 'Nondestructive Testing of Concrete Structures', held at the Malaysian Institute for Nuclear Technology Research (MINT) in Malaysia, which was jointly organized by MINT and the International Atomic Energy Agency (IAEA)

  3. Contaminated concrete surface layer removal

    International Nuclear Information System (INIS)

    Equipment is being developed to economically remove contaminated concrete surfaces in nuclear facilities. To be effective this equipment should minimize personnel radiation exposure, minimize the volume of material removed, and perform the operation quickly with the least amount of energy. Several methods for removing concrete surfaces are evaluated for use in decontaminating such facilities. Two unique methods especially suited for decontamination are described: one, the water cannon, is a device that fires a high-velocity jet of fluid causing spallation of the concrete surface; the other, a concrete spaller, is a tool that exerts radial pressure agains the sides of a pre-dilled shallow cylindrical hole causing spallation to occur. Each method includes a means for containing airborne contamination. Results of tests show that these techniques can rapidly and economically remove surfaces, and leave minimal rubble for controlled disposal

  4. A Research About the Concrete Compression Failure

    OpenAIRE

    Deliang Meng; Huijian Li; Lixin Zhang; Pin Cheng

    2013-01-01

    Concrete material is one of the wide applications materials in the engineering. There is an important implication on national life safety to research its destruction. And size effect of the concrete also has an important impact on failure mechanism and strain injury of the concrete. There are many influencing factors on concrete size effect. In this paper, we will use the numerical simulation method to research the concrete compression failure from two aspects. One is the arrangement of th...

  5. Sustainable Concrete with Recycled Aggregate

    OpenAIRE

    Kara, P

    2012-01-01

    Concretes produced with recycled aggregates are the subject of several papers recently published in the technical literature. Substitution of natural aggregates can be one of possibilities to take care of landfills and increase of CO2 emissions into the atmosphere in Latvia. Recycled aggregate is a valuable resource; value-added consumption of recycled aggregate, as replacement for virgin aggregate in concrete, can yield significant energy and environmental benefits. In present study recycled...

  6. Environmentally friendly, customised sprayed concrete

    OpenAIRE

    Río, Olga

    2010-01-01

    The quality of structural shotcrete or sprayed concrete depends not only on the Same factors as conventional structural concrete, but also on other placement-related issues such as pumping or spraying. Although today's primarily prescriptive design and control tools guarantee quality to some extent, the results are uncertain and mix design procedures do not provide sound information, a priori", on mechanical properties or durabllity. Nor does this approach contribute to design or produce spra...

  7. CONCRETE STORAGE FOR SOLAR THERMAL POWER PLANTS AND INDUSTRIAL PROCESS HEAT

    OpenAIRE

    Laing, Doerte; Lehmann, Dorothea; Bahl, Carsten

    2008-01-01

    Economic storage of thermal energy is a technological key issue for solar thermal power plants and industrial waste heat recovery. Systems using single phase heat transfer fluids like thermal oil, pressurized water, air or superheated steam, demand storage systems for sensible heat. A sensible heat storage system using concrete as storage material has been developed by Ed. Züblin AG and DLR. A major focus was the cost reduction of the heat exchanger and the high temperature concrete storage m...

  8. Performance-based design of self-compacting fibre reinforced concrete

    OpenAIRE

    Grünewald, S

    2004-01-01

    The development of self-compacting concrete (SCC) marks an important milestone in improving the product quality and efficiency of the building industry. SCC homogenously spreads due to its own weight, without any additional compaction energy and does not entrap air. SCC improves the efficiency at the construction sites, enhances the working conditions and the quality and the appearance of concrete. Fibres bridge cracks and retard their propagation. They contribute to an increased energy absor...

  9. Application of Micro-Electro-Mechanical Sensors Contactless NDT of Concrete Structures

    OpenAIRE

    Suyun Ham; Popovics, John S.

    2015-01-01

    The utility of micro-electro-mechanical sensors (MEMS) for application in air-coupled (contactless or noncontact) sensing to concrete nondestructive testing (NDT) is studied in this paper. The fundamental operation and characteristics of MEMS are first described. Then application of MEMS sensors toward established concrete test methods, including vibration resonance, impact-echo, ultrasonic surface wave, and multi-channel analysis of surface waves (MASW), is demonstrated. In each test applic...

  10. Uncertainty associated with convective wet removal of entrained aerosols in a global climate model

    Directory of Open Access Journals (Sweden)

    B. Croft

    2012-11-01

    Full Text Available The uncertainties associated with the wet removal of aerosols entrained above convective cloud bases are investigated in a global aerosol-climate model (ECHAM5-HAM under a set of limiting assumptions for the wet removal of the entrained aerosols. The limiting assumptions for the wet removal of entrained aerosols are negligible scavenging and vigorous scavenging (either through activation, with size-dependent impaction scavenging, or with the prescribed fractions of the standard model. To facilitate this process-based study, an explicit representation of cloud-droplet-borne and ice-crystal-borne aerosol mass and number, for the purpose of wet removal, is introduced into the ECHAM5-HAM model. This replaces and is compared with the prescribed cloud-droplet-borne and ice-crystal-borne aerosol fraction scavenging scheme of the standard model.

    A 20% to 35% uncertainty in simulated global, annual mean aerosol mass burdens and optical depth (AOD is attributed to different assumptions for the wet removal of aerosols entrained above convective cloud bases. Assumptions about the removal of aerosols entrained above convective cloud bases control modeled upper tropospheric aerosol concentrations by as much as one order of magnitude.

    Simulated aerosols entrained above convective cloud bases contribute 20% to 50% of modeled global, annual mean aerosol mass convective wet deposition (about 5% to 10% of the total dry and wet deposition, depending on the aerosol species, when including wet scavenging of those entrained aerosols (either by activation, size-dependent impaction, or with the prescribed fraction scheme. Among the simulations, the prescribed fraction and size-dependent impaction schemes yield the largest global, annual mean aerosol mass convective wet deposition (by about two-fold. However, the prescribed fraction scheme has more vigorous convective mixed-phase wet removal (by two to five-fold relative to the size-dependent impaction

  11. Evaluation of gas entrainment flow rate using numerical simulation with interface-tracking method

    International Nuclear Information System (INIS)

    The gas entrainment (GE) due to free surface vortex is one of the important issues in the safety study on sodium-cooled fast reactors. In fact, a great deal of theoretical, experimental and numerical research has been performed to investigate the GE behaviors. The authors also have conducted a simple experiment to investigate the gas entrainment flow rate under various flow and/or fluid property conditions. In this experiment, a hollow vortex is formed in a cylindrical tank and gas is entrained into liquid when the vortex strength is intensified sufficiently to generate highly-elongated gas core along the vortex core. The influence of fluid property on the gas entrained flow rate also has been investigated experimentally. In this paper, the authors perform numerical simulations of the simple experiment. To simulate interfacial deformations accurately, a high-precision interface-tracking method is employed, in which appropriate physics models, e.g. the mechanical balance model of pressure and surface tension at gas-liquid interface, are introduced. Two kinds of fluids, i.e. water and silicone oil, are considered as the working fluid in the simulations and the flow rate is changed over a wide range as the simulation parameter for both fluids. As a result of the numerical simulations, the evaluated values of the entrained gas flow rate shows good agreement with the experimental data. In addition, both the simulation results and experimental data provide the entrained gas flow rate in proportional to the average velocity at the cylindrical tank outlet. Furthermore, the influence of the fluid property on the entrained gas flow rate observed in the experiment is reproduced by the numerical simulations, that is, the high viscosity fluid, i.e. silicone oil, provides much smaller entrained gas flow rate than that of the low viscosity fluid, i.e. water. Similarly, the proportionality constant between the entrained gas flow rate and the outlet velocity becomes smaller in the

  12. Entrainability of cell cycle oscillator models with exponential growth of cell mass.

    Science.gov (United States)

    Nakao, Mitsuyuki; Enkhkhudulmur, Tsog-Erdene; Katayama, Norihiro; Karashima, Akihiro

    2014-01-01

    Among various aspects of cell cycle, understanding synchronization mechanism of cell cycle is important because of the following reasons. (1)Cycles of cell assembly should synchronize to form an organ. (2) Synchronizing cell cycles are required to experimental analysis of regulatory mechanisms of cell cycles. (3) Cell cycle has a distinct phase relationship with the other biological rhythms such as circadian rhythm. However, forced as well as mutual entrainment mechanisms are not clearly known. In this study, we investigated entrainability of cell cycle models of yeast cell under the periodic forcing to both of the cell mass and molecular dynamics. Dynamics of models under study involve the cell mass growing exponentially. In our result, they are shown to allow only a limited frequency range for being entrained by the periodic forcing. In contrast, models with linear growth are shown to be entrained in a wider frequency range. It is concluded that if the cell mass is included in the cell cycle regulation, its entrainability is sensitive to a shape of growth curve assumed in the model. PMID:25571564

  13. Interpretations of Frequency Domain Analyses of Neural Entrainment: Periodicity, Fundamental Frequency, and Harmonics

    Science.gov (United States)

    Zhou, Hong; Melloni, Lucia; Poeppel, David; Ding, Nai

    2016-01-01

    Brain activity can follow the rhythms of dynamic sensory stimuli, such as speech and music, a phenomenon called neural entrainment. It has been hypothesized that low-frequency neural entrainment in the neural delta and theta bands provides a potential mechanism to represent and integrate temporal information. Low-frequency neural entrainment is often studied using periodically changing stimuli and is analyzed in the frequency domain using the Fourier analysis. The Fourier analysis decomposes a periodic signal into harmonically related sinusoids. However, it is not intuitive how these harmonically related components are related to the response waveform. Here, we explain the interpretation of response harmonics, with a special focus on very low-frequency neural entrainment near 1 Hz. It is illustrated why neural responses repeating at f Hz do not necessarily generate any neural response at f Hz in the Fourier spectrum. A strong neural response at f Hz indicates that the time scales of the neural response waveform within each cycle match the time scales of the stimulus rhythm. Therefore, neural entrainment at very low frequency implies not only that the neural response repeats at f Hz but also that each period of the neural response is a slow wave matching the time scale of a f Hz sinusoid. PMID:27375465

  14. Searching for roots of entrainment and joint action in early musical interactions

    Directory of Open Access Journals (Sweden)

    Jessica ePhillips-Silver

    2012-02-01

    Full Text Available When people play music and dance together, they engage in forms of musical joint action that are often characterized by a shared sense of rhythmic timing and affective state (i.e., temporal and affective entrainment. In order to understand the origins of musical joint action, we propose a model in which entrainment is linked to dual mechanisms (motor resonance and action simulation, which in turn support musical behavior (imitation and complementary joint action. To illustrate this model, we consider two generic forms of joint musical behavior: chorusing and turn-taking. We explore how these common behaviors can be founded on entrainment capacities established early in human development, specifically during musical interactions between infants and their caregivers. If the roots of entrainment are found in early musical interactions which are practiced from childhood into adulthood, then we propose that the rehearsal of advanced musical ensemble skills can be considered to be a refined, mimetic form of temporal and affective entrainment whose evolution begins in infancy.

  15. Positive feedback and momentum growth during debris-flow entrainment of wet bed sediment

    Science.gov (United States)

    Iverson, R.M.; Reid, M.E.; Logan, M.; LaHusen, R.G.; Godt, J.W.; Griswold, J.P.

    2011-01-01

    Debris flows typically occur when intense rainfall or snowmelt triggers landslides or extensive erosion on steep, debris-mantled slopes. The flows can then grow dramatically in size and speed as they entrain material from their beds and banks, but the mechanism of this growth is unclear. Indeed, momentum conservation implies that entrainment of static material should retard the motion of the flows if friction remains unchanged. Here we use data from large-scale experiments to assess the entrainment of bed material by debris flows. We find that entrainment is accompanied by increased flow momentum and speed only if large positive pore pressures develop in wet bed sediments as the sediments are overridden by debris flows. The increased pore pressure facilitates progressive scour of the bed, reduces basal friction and instigates positive feedback that causes flow speed, mass and momentum to increase. If dryer bed sediment is entrained, however, the feedback becomes negative and flow momentum declines. We infer that analogous feedbacks could operate in other types of gravity-driven mass flow that interact with erodible beds. ?? 2011 Macmillan Publishers Limited. All rights reserved.

  16. MAIN MODIFICATIONS OF READY MIX CONCRETE STATIONS HAVING MODULAR-BLOCK LINE-UP

    Directory of Open Access Journals (Sweden)

    S. N. Leonovich

    2015-01-01

    Full Text Available The paper considers a new BNTU development that is concrete complexes having modular-block design. The modular-block approach presupposes to divide the whole technological chain for production of concrete and mortar mixes into separate sections (modules, each of which performs specific functions and can be used separately and independently of others. Then it is necessary to select such set of modules that ensure production of concrete and mortars. The paper presents designs of main modules in the technological chain for preparation of concrete mixes: a concrete mixing module, a storage and supply module of inert materials, a storage and supply module of cement and a number of additional auxiliary modules (a concrete supply module, a module for preparation of chemical additives, an operator module and a module for preparation and supply of air.Two main modifications of ready mix concrete stations developed on the basis of modular-block principle using basic modules are given in the paper. The first modification is a stationary concrete-mortar complex characterized by high productivity, large reserves of aggregates and cement, ability to be operated in winter due to heat insulation and water heating system and inert materials. The second modification is a transportable option that permits to transport the station from place to place due to reduction of time required for its installation and removal and execute production of concrete mixtures in the vicinity of the object construction. This options provides the possibility to reduce expenses on concrete transportation to the place of its deposit and decrease the probability of deterioration of consumer properties of the concrete mix that in its turn entails reduction in final cost of the object construction and improves quality of the construction.

  17. Measuring strain and stress distributions along rebar embedded in concrete using time-of-flight neutron diffraction

    International Nuclear Information System (INIS)

    In modern society, architectural and civil engineering structures such as reinforced concrete buildings require high seismic performance to minimize the ‘megarisk’ exposed from urban earthquake hazards. In the reinforced concrete structures, the bond resistance between rebar and concrete is one important parameter for discussing its performance and it has been typically evaluated by measuring the strain distribution along the embedded rebar. Here, we present in-situ strain and stress measurements for the rebar in reinforced concrete using time-of-flight neutron diffraction as a novel alternative technique to typical strain gauges. It was demonstrated in this study that the three-dimensional deformation behavior of the embedded rebar in normal-strength concrete, cured in air, can be accurately measured under pull-out loading using time-of-flight neutron diffraction. Wider applications of neutron diffraction in the structural engineering field are expected for advanced understanding of actual phenomena on reinforced concrete structures. (paper)

  18. Comparison of Performance of Standard Concrete And Fibre Reinforced Standard Concrete Exposed To Elevated Temperatures

    OpenAIRE

    K. Srinivasa Rao

    2013-01-01

    Concrete elements exposed to fire undergo temperature gradients and as a result, undergo physical changes or spalling which leads to expose steel reinforcement. This causes distress in concrete structures. The performance of concrete can be improved with the addition of steel fibres to concrete especially when it is exposed to heat. Therefore, this study has been carried out to generate experimental data on standard concrete ofgrade M45 and Fiber Reinforced Standard Concrete exposed to elevat...

  19. Use of recycled plastic in concrete: a review.

    Science.gov (United States)

    Siddique, Rafat; Khatib, Jamal; Kaur, Inderpreet

    2008-01-01

    Numerous waste materials are generated from manufacturing processes, service industries and municipal solid wastes. The increasing awareness about the environment has tremendously contributed to the concerns related with disposal of the generated wastes. Solid waste management is one of the major environmental concerns in the world. With the scarcity of space for landfilling and due to its ever increasing cost, waste utilization has become an attractive alternative to disposal. Research is being carried out on the utilization of waste products in concrete. Such waste products include discarded tires, plastic, glass, steel, burnt foundry sand, and coal combustion by-products (CCBs). Each of these waste products has provided a specific effect on the properties of fresh and hardened concrete. The use of waste products in concrete not only makes it economical, but also helps in reducing disposal problems. Reuse of bulky wastes is considered the best environmental alternative for solving the problem of disposal. One such waste is plastic, which could be used in various applications. However, efforts have also been made to explore its use in concrete/asphalt concrete. The development of new construction materials using recycled plastics is important to both the construction and the plastic recycling industries. This paper presents a detailed review about waste and recycled plastics, waste management options, and research published on the effect of recycled plastic on the fresh and hardened properties of concrete. The effect of recycled and waste plastic on bulk density, air content, workability, compressive strength, splitting tensile strength, modulus of elasticity, impact resistance, permeability, and abrasion resistance is discussed in this paper. PMID:17981022

  20. Use of recycled plastic in concrete: A review

    International Nuclear Information System (INIS)

    Numerous waste materials are generated from manufacturing processes, service industries and municipal solid wastes. The increasing awareness about the environment has tremendously contributed to the concerns related with disposal of the generated wastes. Solid waste management is one of the major environmental concerns in the world. With the scarcity of space for landfilling and due to its ever increasing cost, waste utilization has become an attractive alternative to disposal. Research is being carried out on the utilization of waste products in concrete. Such waste products include discarded tires, plastic, glass, steel, burnt foundry sand, and coal combustion by-products (CCBs). Each of these waste products has provided a specific effect on the properties of fresh and hardened concrete. The use of waste products in concrete not only makes it economical, but also helps in reducing disposal problems. Reuse of bulky wastes is considered the best environmental alternative for solving the problem of disposal. One such waste is plastic, which could be used in various applications. However, efforts have also been made to explore its use in concrete/asphalt concrete. The development of new construction materials using recycled plastics is important to both the construction and the plastic recycling industries. This paper presents a detailed review about waste and recycled plastics, waste management options, and research published on the effect of recycled plastic on the fresh and hardened properties of concrete. The effect of recycled and waste plastic on bulk density, air content, workability, compressive strength, splitting tensile strength, modulus of elasticity, impact resistance, permeability, and abrasion resistance is discussed in this paper