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1
Rezzoug, A., A. Alexis, and P. Thomas. "Écoulement à surface libre dans un massif de sol soumis à la marée : comparaison théorie-expérimentation." Canadian Geotechnical Journal 36, no. 1 (August 8, 1999): 13–20. http://dx.doi.org/10.1139/t98-078.
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We analyze analytically and numerically the stress distribution along the plug-rock interface and within an axially loaded plug emplaced in a borehole in rock. Experiments show that the interface strength increases with decreasing plug radius and with increasing plug length. Axial strength decreases as a power law of plug radius. An increase in the modulus ratio (ratio of plug modulus to rock modulus) increases the interface strength, until it levels off at a ratio of about 5.0. For short plugs, the tensile stresses may reach a magnitude significant to be of concern for long-term stability of the plug and of the host rock. Out studies suggest designing friction plugs with a length to radius ratio of at least 8.0. In practice, especially for short-term performance, e.g., emergency flood control or temporary diversions, a ratio of 8.0 may not be necessary or justified. For permanent abandonment plugs, it is essential to reduce the tensile stresses in the plug and in the host rock to a level that will minimize the risk of long-term deterioration. We recommend in situ experiments on larger diameter plugs to assess the validity of the proposed size effect extrapolation obtained in this study. Key words: borehole plugging (sealing), shaft seal design, plug-rock interface strength, axial strength, bond strength, cement grout.
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Akgün, Haluk, and Jaak JK Daemen. "Design implications of analytical and laboratory studies of permanent abandonment plugs." Canadian Geotechnical Journal 36, no. 1 (August 8, 1999): 21–38. http://dx.doi.org/10.1139/t98-089.
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We analyze analytically and numerically the stress distribution along the plug-rock interface and within an axially loaded plug emplaced in a borehole in rock. Experiments show that the interface strength increases with decreasing plug radius and with increasing plug length. Axial strength decreases as a power law of plug radius. An increase in the modulus ratio (ratio of plug modulus to rock modulus) increases the interface strength, until it levels off at a ratio of about 5.0. For short plugs, the tensile stresses may reach a magnitude significant to be of concern for long-term stability of the plug and of the host rock. Our studies suggest designing friction plugs with a length to radius ratio of at least 8.0. In practice, especially for short-term performance, e.g., emergency flood control or temporary diversions, a ratio of 8.0 may not be necessary or justified. For permanent abandonment plugs, it is essential to reduce the tensile stresses in the plug and in the host rock to a level that will minimize the risk of long-term deterioration. We recommend in situ experiments on larger diameter plugs to assess the validity of the proposed size effect extrapolation obtained in this study.Key words: borehole plugging (sealing), shaft seal design, plug-rock interface strength, axial strength, bond strength, cement grout.
3
Tang, Geng, Hui Yan, Jun Li, Xue Feng Song, Xin Zhang, and Xue Li Guo. "Sealing Analysis of Cement Plug in Offshore Abandoned Wells." Materials Science Forum 993 (May 2020): 1333–40. http://dx.doi.org/10.4028/www.scientific.net/msf.993.1333.
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A three-dimensional finite element model of stratum-cement ring-casing-cement plug was established for the failure analysis of the cement plug seal in the abandoned oil and gas wells. The mechanical parameters, length, bottom fluid pressure and casing swaging length of the cement plug under non-uniform ground stress conditions were analyzed. The results showed that when the bottom of the cement plug was subjected to fluid pressure, the stress at the interface between the cement plug and the casing increased, and thereby the cement plug at the bottom and the cementation of the casing failed, resulting in a the decrease in the sealing performance of the cement plug, which may be sealed under fluid corrosion. As the modulus of elasticity and the radius of the cement plug increased, the cement plug stress and the cement failure length increased. As the cement plug length increased, the cement plug stress and the cement failure length decreased, while Poisson's ratio for the cement plug stress and the cement failure length increased. The increase of the bottom fluid pressure could increase the cement plug stress and the cementation failure length. In the abandoned well, where the casing was forged and then grinded after the casing was forged, the length of the casing milling increased, the plug stress of cement reduced. These findings can provide insightful potentials for the parameters of cement plugs when the cement plugs are closed in the offshore oil and gas wells.
4
Sano, Yukio, Koji Tokushima, and Tokujiro Inoue. "Multishock Compactions of a Die-Contained Copper Powder Medium Analyzed by Improved Theory." Journal of Pressure Vessel Technology 113, no. 4 (November 1, 1991): 560–69. http://dx.doi.org/10.1115/1.2928796.
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In the present paper, the multishock compaction process of a die-contained copper powder medium supported by an elastic plug at one end and impacted by an elastic punch at the other end, is analyzed by means of an improved theory having the effect of elasticity of the punch and plug. The compactions computed first have a constant sum of lengths of the medium and plug S0*=110, a constant ratio of punch mass to powder mass filled in the die M*=20, and an initial punch velocity ν0=50m/s. The computations of the compactions for the medium with very short lengths and the plug with long lengths confirm the existence of the medium length Scr1* corresponding to the first critical plug-length found in the previous study, and support the compaction process and the final mean density ρmean*-initial medium length S* relation of the medium shorter than the length Scr1* which were inferred in the study. Furthermore, the effect of elastic waves in the punch and plug on the process of the medium longer than Scr1* are examined. There are one common factor and one significant different factor in the processes. Explicitly, the waves in the plug exert different influence on compaction processes of the medium with different lengths, whereas the waves in the punch have similar influence on the processes. The elastic waves in the plug and die wall friction cause the medium length Scr2* corresponding to the second critical plug-length inferred in the previous study. Moreover, the waves in the plug make the form of the computed relation curve more complicated than the inferred one. The computed curve has the lengths Scr3* and Scr4* at which the density has an extreme value, respectively. Approximate similarity conditions for the compactions with various values of S0* are given by two fixed parameters M* and ν0 in region S*<Scr1*, three fixed parameters S*/S0*, M*, and ν0 in region from Scr1* to small S* where the wall friction effect can be neglected, and three fixed parameters S*, M*, and ν0 in region S*>(1/2)S0*. The computed ρmean*–S* and ρmean*–S*/S0* relations support these conditions. Furthermore, the computations of the compactions reveal that the waves in the punch, medium, and plug behave in similar manner during the processes, though they have different strengths.
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Ko, Junyoung, and Sangseom Jeong. "Plugging effect of open-ended piles in sandy soil." Canadian Geotechnical Journal 52, no. 5 (May 2015): 535–47. http://dx.doi.org/10.1139/cgj-2014-0041.
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This paper presents an experimental study of the plugging effect on the capacity of open-ended piles installed in sandy soil. Full-scale tests, including dynamic and static axial compression load tests, were carried out on three instrumented piles with different diameters (508.0, 711.2, and 914.4 mm). To measure the outer and inner shaft resistances acting on the piles, a double-walled system was utilized, with instrumented strain gauges on the outside and inside walls of the pile. The results of field tests show that the inner shaft resistance was mostly mobilized at the location between the pile tip and 18%–34% of the total plug length. It was found that the soil plugging in the lower portion has influence on the inner shaft resistance. In addition, it can be also demonstrated that the ratio of inner shaft resistance plus annulus load resistance to total resistance was decreased with increasing pile diameters. The results of these tests show that the relationship between the degree of plugging and pile diameter is clearly established. Direct observations of the soil plugs were made and used to quantify both the plug length ratio (PLR) and the incremental filling ratio (IFR). Based on this result, it was realized that the N value of the standard penetration test (SPT) is highly correlated with the IFR.
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Jain, Sneha M., Priya M. Pradhan, Supratim Sen, and Bharat V. Dalvi. "Transcatheter closure of elongated and pulmonary hypertensive patent arterial duct in infants using Amplatzer vascular plug II." Cardiology in the Young 30, no. 2 (January 30, 2020): 243–48. http://dx.doi.org/10.1017/s1047951120000104.
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AbstractObjective:To evaluate the feasibility, efficacy, and safety of Amplatzer vascular plug II in large and elongated ducts in infants.Introduction:Patent arterial duct device closure is technically challenging in infants with large and elongated ducts because Amplatzer duct occluder and Amplatzer duct occluder II have high chances of causing aortic coarctation and left pulmonary artery stenosis, respectively. The Amplatzer vascular plug II being soft with no retention discs on either sides helps in mitigating these problems.Method:This is a prospective, observational study involving infants with clinical, echocardiographic and angiographic evidence of large left to right shunt. All the children underwent duct closure using Amplatzer vascular plug II.Results:Eighteen infants qualified for the study. Mean age and weight were 8.63 ± 3.84 months and 6.3 ± 1.7 kg, respectively. The angiographic mean duct diameter at the pulmonary artery end was 4.66 ± 0.92 mm, and the mean duct length was 9.4 ± 2.48 mm. The size of Amplatzer vascular plug II used varied from 6 mm to 10 mm. Technical success was achieved in 16/18 cases. One patient had device embolisation, and in the other, the device was found to be unstable. The ratio of Amplatzer vascular plug II size to the duct diameter was 1.65 ± 0.27, while the ratio of ductal length to device length was 1.48 ± 0.46 in those with successful outcome.Conclusions:Amplatzer vascular plug II is a safe and effective option in appropriately selected infants with elongated ducts. Diameter and length of Amplatzer vascular plug II vis-a-vis those of the ductus are important determinants of the successful outcome.
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Jiang, Xiu Gen, Yang Yang, Feng Jie Zhang, Jin San Ju, and Xiao Chuan You. "Analysis of the Load-Carrying Capability of the Casing Plug Joint of Steel Tube Structures Considering the Contact Effect." Advanced Materials Research 33-37 (March 2008): 321–26. http://dx.doi.org/10.4028/www.scientific.net/amr.33-37.321.
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Nonlinear finite element model analysis of the casing plug joints of steel tubular has been realized by ANSYS software. The law of load-carrying capability and stiffness of joint are separately gained by changing the ratio of length and diameter (R/L) and the ratio of the casing length and the main tube length (l/L). The influence of the casing thickness on the load-carrying capability and stiffness are also discussed. The results indicated that the load-carrying capability and stiffness of the joints both increase with the ratio(R/L) increment and the ratio of the casing length and main tube length (l/L). When the main tube thickness is equal to casing thickness, the load-carrying capacity of joints achieves the most.
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Cassidy, K. J., N. Gavriely, and J. B. Grotberg. "Liquid Plug Flow in Straight and Bifurcating Tubes." Journal of Biomechanical Engineering 123, no. 6 (June 7, 2001): 580–89. http://dx.doi.org/10.1115/1.1406949.
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A finite-length liquid plug may be present in an airway due to disease, airway closure, or by direct instillation for medical therapy. Air forced by ventilation propagates the plug through the airways, where it deposits fluid onto the airway walls. The plug may encounter single or bifurcating airways, an airway surface liquid, and other liquid plugs in nearby airways. In order to understand how these flow situations influence plug transport, benchtop experiments are performed for liquid plug flow in: Case (i) straight dry tubes, Case (ii) straight pre-wetted tubes, Case (iii) bifurcating dry tubes, and Case (iv) bifurcating tubes with a liquid blockage in one daughter. Data are obtained for the trailing film thickness and plug splitting ratio as a function of capillary number and plug volumes. For Case (i), the finite length plug in a dry tube has similar behavior to a semi-infinite plug. For Case (ii), the trailing film thickness is dependent upon the plug capillary number (Ca) and not the precursor film thickness, although the shortening or lengthening of the liquid plug is influenced by the precursor film. For Case (iii), the plug splits evenly between the two daughters and the deposited film thickness depends on the local plug Ca, except for a small discrepancy that may be due to an entrance effect or from curvature of the tubes. For Case (iv), a plug passing from the parent to daughters will deliver more liquid to the unblocked daughter (nearly double, consistently) and then the plug will then travel at greater Ca in the unblocked daughter as the blocked. The flow asymmetry is enhanced for a larger blockage volume and diminished for a larger parent plug volume and parent-Ca.
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Zheng, Y., H. Fujioka, J. C. Grotberg, and J. B. Grotberg. "Effects of Inertia and Gravity on Liquid Plug Splitting at a Bifurcation." Journal of Biomechanical Engineering 128, no. 5 (April 19, 2006): 707–16. http://dx.doi.org/10.1115/1.2246235.
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Liquid plugs may form in pulmonary airways during the process of liquid instillation or removal in many clinical treatments. During inspiration the plug may split at airway bifurcations and lead to a nonuniform final liquid distribution, which can adversely affect treatment outcomes. In this paper, a combination of bench top experimental and theoretical studies is presented to study the effects of inertia and gravity on plug splitting in an airway bifurcation model to simulate the liquid distributions in large airways. The splitting ratio, Rs, is defined as the ratio of the plug volume entering the upper (gravitationally opposed) daughter tube to the lower (gravitationally favored) one. Rs is measured as a function of parent tube Reynolds number, Rep; gravitational orientations for roll angle, ϕ, and pitch angle, γ; parent plug length LP; and the presence of pre-existing plug blockages in downstream daughter tubes. Results show that increasing Rep causes more homogeneous splitting. A critical Reynolds number Rec is found to exist so that when Rep⩽Rec, Rs=0, i.e., no liquid enters the upper daughter tube. Rec increases while Rs decreases with increasing the gravitational effect, i.e., increasing ϕ and γ. When a blockage exists in the lower daughter, Rec is only found at ϕ=60deg in the range of Rep studied, and the resulting total mass ratio can be as high as 6, which also asymptotes to a finite value for different ϕ as Rep increases. Inertia is further demonstrated to cause more homogeneous plug splitting from a comparison study of Rs versus Cap (another characteristic speed) for three liquids: water, glycerin, and LB-400X. A theoretical model based on entrance flow for the plug in the daughters is developed and predicts Rs versus Rep. The frictional pressure drop, as a part of the total pressure drop, is estimated by two fitting parameters and shows a linear relationship with Rep. The theory provides a good prediction on liquid plug splitting and well simulates the liquid distributions in the large airways of human lungs.
10
Dini-Papanastasi, O., P. Kostopoulou, and K. Radoglou. "Effects of seed origin, growing medium and mini-plug density on early growth and quality of black locust (Robinia pseudoacacia [L.]) seedlings." Journal of Forest Science 58, No. 1 (January 27, 2012): 8–20. http://dx.doi.org/10.17221/46/2011-jfs.
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The objective of this study was to identify optimal growing conditions for the production of high-quality mini-plug seedlings of black locust (Robinia pseudoacacia [L.].). Two seed origins (Greek and Hungarian), two growing media (enriched peat and stabilized medium) and four mini-plug densities (975; 1,460; 1,820 and 3,500 mini-plugs·m<sup>–2</sup>) were tested in two phases, in growth chambers and in a nursery after transplanting the mini-plugs into larger containers. Measurements included seedling survival, growth traits (root length, shoot height, leaf area, root dry mass, shoot dry mass, root/shoot ratio) and root growth potential (RGP). In addition, the ratio of variable to maximal fluorescence (F<sub>v</sub>/F<sub>m</sub>) and the effective quantum yield of photosystem II (ΔF/F’<sub>m</sub>) were measured. It was found that growing medium produced significant effects mainly in the first phase and seed origin in the second phase while mini-plug density was important in both phases. The F<sub>v</sub>/F<sub>m </sub>ratio was found to be significantly affected by growing medium while the effective quantum yield was influenced by density. Early survival of seedlings was closely correlated with fluorescence and growth traits (particularly with plant height) suggesting that these parameters might be useful for the grading of black locust seedlings prior to transplanting.
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Zamankhan, Parsa, Brian T. Helenbrook, Shuichi Takayama, and James B. Grotberg. "Steady motion of Bingham liquid plugs in two-dimensional channels." Journal of Fluid Mechanics 705 (December 12, 2011): 258–79. http://dx.doi.org/10.1017/jfm.2011.438.
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AbstractWe study numerically the steady creeping motion of Bingham liquid plugs in two-dimensional channels as a model of mucus behaviour during airway reopening in pulmonary airways. In addition to flow analysis related to propagation of the plug, the stress distribution on the wall is studied for better understanding of potential airway epithelial cell injury mechanisms. The yield stress behaviour of the fluid was implemented through a regularized constitutive equation. The capillary number, $\mathit{Ca}$, and the Bingham number, $\mathit{Bn}$, which is the ratio of the yield stress to a characteristic viscous stress, varied over the ranges 0.025–0.1 and 0–1.5, respectively. For the range of parameters studied, it was found that, while the yield stress reduces the magnitude of the shearing along the wall, it can magnify the amplitude of the wall shear stress gradient significantly, and also it can elevate the magnitude of the wall shear stress and wall pressure gradient up to 30 % and 15 %, respectively. Therefore, the motion of mucus plugs can be more damaging to the airway epithelial cells due to the yield stress properties of mucus. The yield stress also modifies the profile of the plug where the amplitude of the capillary waves at the leading meniscus decreases with increase in $\mathit{Bn}$. Other findings are that: the thickness of the static film increases with increasing $\mathit{Bn}$; the driving pressure difference increases linearly with $\mathit{Bn}$; and increasing $\mathit{Bn}$ extends any wall stagnation point beneath the leading meniscus to an unyielded line segment beneath the leading meniscus. With an increase in $\mathit{Bn}$, the unyielded areas appear and grow in the adjacent wall film as well as the core region of the plug between the two menisci. The plug length, ${L}_{P} $, mostly modifies the topology of the yield surfaces. It was found that the unyielded area in the core region between the two menisci grows as the plug length decreases. The very short Bingham plug behaves like a solid lamella. In all computed liquid plugs moving steadily, the von Mises stress attains its maximum value near the interface of the leading meniscus in the transition region. For Bingham plugs moving very slowly, $\mathit{Ca}\ensuremath{\rightarrow} 0$, the driving pressure is non-zero.
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Zhang, Zhibin, Chunxi Lin, Weiqiang Ye, An Wei, Leming Xiao, and Wanzheng Ai. "Research on the Flow Characteristics of Sudden-Reduction Oil Tube." Open Mechanical Engineering Journal 9, no. 1 (February 20, 2015): 77–79. http://dx.doi.org/10.2174/1874155x01509010077.
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The backflow region length in sudden-reduction oil tube is not only closely associated with its energy loss, but is also closely related to the partition between orifice plate and plug. In this paper, the characteristics of backflow region length in sudden-reduction oil tube are researched. The results illustrated that backflow region length decreases with the increase in the contraction ratio. Moreover, when Reynolds number is more than 105, Reynolds number has little impact on backflow region length. Empirical expression about backflow region length in sudden-reduction oil tube is also discussed in this paper.
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Mu, Mingfei, Xinghu Li, Yong Qiu, and Yang Shi. "Study on a New Gasoline Particulate Filter Structure Based on the Nested Cylinder and Diversion Channel Plug." Energies 12, no. 11 (May 28, 2019): 2045. http://dx.doi.org/10.3390/en12112045.
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Increasingly stringent emission regulations have imposed strict requirements on the particulate matter (PM) from gasoline direct injection (GDI) engines, and the gasoline particulate filters (GPFs) are considered one of the most promising devices for meeting these requirement. To reduce the flow resistance of the GPF, a type of nested cylinder and diversion channel plug (NC-DCP) GPF is designed. It is composed of nested foam metal cylinders and annular diversion channel plugs. The pressure drop and its influencing factors were theoretically studied. The results show that the structural parameters, such as the cylindrical layer spacing and the length-to-diameter ratio, and the pressure drop have trade-off relationships. Moreover, the filtration efficiency is analyzed, and the calculation formula is summarized. The internal flow field distribution and its influencing factors are discussed based on a 2-D axisymmetric simulation. The results show that the exhaust velocity affects the flow field uniformity but does not affect the flow field structure. The pressure drop gradually decreases as the number of nested layers increases, and the positive direction is beneficial to reduce the overall pressure drop. Under different velocities, there is an optimal length-to-diameter ratio to minimize the pressure drop, and the simicircular diversion plug greatly improves the flow uniformity index for the internal flow field of the filter element.
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Kitaya, Yoshiaki, Genhua Niu, Toyoki Kozai, and Maki Ohashi. "Photosynthetic Photon Flux, Photoperiod, and CO2 Concentration Affect Growth and Morphology of Lettuce Plug Transplants." HortScience 33, no. 6 (October 1998): 988–91. http://dx.doi.org/10.21273/hortsci.33.6.988.
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Lettuce (Lactuca sativa L. cv. Summer-green) plug transplants were grown for 3 weeks under 16 combinations of four levels (100, 150, 200, and 300 μmol·m-2·s-1) of photosynthetic photon flux (PPF), two photoperiods (16 and 24 h), and two levels of CO2 (400 and 800 μmol·mol-1) in growth chambers maintained at an air temperature of 20 ±2 °C. As PPF increased, dry mass (DM), percent DM, and leaf number increased, while ratio of shoot to root dry mass (S/R), ratio of leaf length to leaf width (LL/LW), specific leaf area, and hypocotyl length decreased. At the same PPF, DM was increased by 25% to 100% and 10% to 100% with extended photoperiod and elevated CO2 concentration, respectively. Dry mass, percent DM, and leaf number increased linearly with daily light integral (DLI, the product of PPF and photoperiod), while S/R, specific leaf area, LL/LW and hypocotyl length decreased as DLI increased under each CO2 concentration. Hypocotyl length was influenced by PPF and photoperiod, but not by CO2 concentration. Leaf morphology, which can be reflected by LL/LW, was substantially influenced by PPF at 100 to 200 μmol·m-2·s-1, but not at 200 to 300 μmol·m-2·s-1. At the same DLI, the longer photoperiod promoted growth under the low CO2 concentration, but not under the high CO2 concentration. Longer photoperiod and/or higher CO2 concentration compensated for a low PPF.
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Tilz, Anton, Georg Meyer, Constantin Kiesling, Gerhard Pirker, Sebastian Salbrechter, and Andreas Wimmer. "Design of a test rig for fundamental investigations of spark characteristics." International Journal of Engine Research 21, no. 8 (February 21, 2019): 1412–25. http://dx.doi.org/10.1177/1468087419828943.
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A common means to increase efficiency in stationary spark ignited engines is to operate the engine with a higher air/fuel ratio of the mixture in conjunction with a higher turbulence level; however, this generally leads to severe conditions that significantly impact the inflammability of the gas–air mixture and combustion stability. Because the electric arc that forms at the spark plug is a main influencing factor in combustion, detailed research work in the field of electric arc behavior generated at spark plugs is required. This article thus presents a specially tailored test rig that is designed to facilitate an investigation of electric arc behavior under cross-flows at a spark plug typically used in gas engines. The test rig consists of a closed flow circuit for inert gases; its centerpiece is a test cell that provides optical access for high-speed imaging of the electric arc behavior at the spark plug. The required flow velocity at the spark plug is set with a blower. Flow velocities up to 30 m/s, pressures up to 60 bar and temperatures up to 80 °C can be achieved inside the flow system at the location of the spark plug. Postprocessing algorithms have been developed to automatically extract information from the high-speed images. The results reveal that the arc stretches more at a higher flow velocity as indicated by its greater arc length. In addition, it is evident that the cycle-to-cycle variation in arc length increases at higher flow velocities. The secondary voltage history and its cycle-to-cycle variation are strongly influenced by the arc length. This is reflected in the cycle-to-cycle variation of the spark energy input to the flowing gas. These results support the conclusion that spark behavior itself can be a substantial source of cycle-to-cycle variation in the combustion process observed in spark ignited gas engines.
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Tian, He, Ziwang Lu, Xu Wang, Xinlong Zhang, Yong Huang, and Guangyu Tian. "A length ratio based neural network energy management strategy for online control of plug-in hybrid electric city bus." Applied Energy 177 (September 2016): 71–80. http://dx.doi.org/10.1016/j.apenergy.2016.05.086.
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Riungu, Joy, Mariska Ronteltap, and Jules B. van Lier. "Volatile fatty acids build-up and its effect on E. coli inactivation during excreta stabilisation in single-stage and two-stage systems." Journal of Water, Sanitation and Hygiene for Development 8, no. 2 (March 19, 2018): 257–67. http://dx.doi.org/10.2166/washdev.2018.160.
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Abstract Digestion and co-digestion of faecal matter collected from urine diverting dehydrating toilet faeces (UDDT-F) and mixed organic market waste (OMW) was studied in single stage pilot scale mesophilic plug-flow anaerobic reactors at UDDT-F:OMW ratios 4:1 and 1:0. Escherichia coli inactivation and volatile fatty acids (VFA) build-up was monitored at sampling points located along the reactor profile. When applying UDDT-F:OMW ratio of 4:1 at 12% total solids (TS), E. coli inactivation achieved was 2.3 log times higher than that achieved in UDDT-F:OMW ratio of 1:0. In subsequent trials, a two-stage reactor was researched, applying a UDDT-F:OMW ratio of 4:1 and 10 or 12% TS slurry concentrations. Highest VFA concentrations of 16.3 ± 1.3 g/L were obtained at a pH of 4.9 in the hydrolysis/acidogenesis reactor, applying a UDDT-F:OMW ratio of 4:1 and 12% TS, corresponding to a non-dissociated (ND)-VFA concentration of 6.9 ± 2.0 g/L. The corresponding decay rate reached a value of 1.6 per day. In the subsequent methanogenic plug-flow reactor, a decay rate of 1.1 per day was attained within the first third part of the reactor length, which declined to 0.6 per day within the last third part of the reactor length. Results show that a two-stage system is an efficient way to enhance pathogen inactivation during anaerobic digestion.
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Toporov, Vladimir A., Aleksandr Bogatov, and Danis Nukhov. "Study of the Tubular Billets Geometric Characteristics during Computer Simulation of the Rotary Piercing Process." Materials Science Forum 946 (February 2019): 788–93. http://dx.doi.org/10.4028/www.scientific.net/msf.946.788.
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The results of the computer simulation of the tubular billet rotary piercing process are presented. The research methodology of the deformation zone geometric ratios with due regard for the tubular billet change of shape at each helical curve step was developed .The changes pattern of the helical curve step length (li), quotient reduction (Δr/r0), ratio of the tubular billet radius to the contact surface width (r/b), contact surface length of the tubular billet (l0) with a roll, depending on the feed angle (β), roll rotation frequency (N) and plug nose extension at the gorge (Сg) was established.
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Si, Yaping, and Royal D. Heins. "Influence of Day and Night Temperatures on Sweet Pepper Seedling Development." Journal of the American Society for Horticultural Science 121, no. 4 (July 1996): 699–704. http://dx.doi.org/10.21273/jashs.121.4.699.
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Sweet pepper (Capsicum annuum `Resistant Giant no. 4') seedlings were grown for 6 weeks in 128-cell plug trays under 16 day/night temperature (DT/NT) regimes from 14 to 26 °C. Seedling stem length, internode length, stem diameter, leaf area, internode and leaf count, plant volume, shoot dry weight (DW), seedling index, and leaf unfolding rate (LUR) were primarily functions of average daily temperature (ADT); i.e., DT and NT had similar effects on each growth or development parameter. Compared to ADT, the difference (DIF, where DIF = DT - NT) between DT and NT had a smaller but still statistically significant effect on stem and internode length, leaf area, plant volume, stem diameter, and seedling index. DIF had no effect on internode and leaf count, shoot DW, and LUR. The root: shoot ratio and leaf reflectance were affected by DT and DIF. Positive DIF (DT higher than NT) caused darker-green leaf color than negative DIF. The node at which the first flower initiated was related to NT. The number of nodes to the first flower on pepper plugs grown at 26 C NT was 1.2 fewer than those of plants grown at 14 °C NT.
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Toporov, Vladimir A., Aleksandr Bogatov, and Danis Nukhov. "Computer-Simulation of the Billet Shape Change during Helical Piercing." Solid State Phenomena 299 (January 2020): 386–91. http://dx.doi.org/10.4028/www.scientific.net/ssp.299.386.
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In this paper the task of the study of the deformation during helical piercing of the metal was set and solved with the use of the DEFORM-3D software. Methodology, that allows to calculate the length of helix lead along the deformation zone, as well as determine for each lead absolute and relative reduction, the width of the contact area and the metal strain refinement indicator was developed. Based on the developed methodology application the following variation regularities were established: helix lead length (li), quotient reduction (Δr/r0), ratio of the billet radius to the width of the contact area (r0/b), as well as the length of the billet contact surface (l0) with the roll in dependence of the feed angle (β), the roll number of revolutions (N) and the plug nose advancement over the gorge (Cg).
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LINDEN, P. F., and J. S. TURNER. "The formation of ‘optimal’ vortex rings, and the efficiency of propulsion devices." Journal of Fluid Mechanics 427 (January 25, 2001): 61–72. http://dx.doi.org/10.1017/s0022112000002263.
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The formation of an axisymmetric vortex ring by forcing uid impulsively through a pipe is examined. An idealized model of the circulation, impulse and energy provided by the injected plug is developed, and these quantities are equated to the corresponding properties of the class of rings with finite cores described by Norbury (1973). It is shown that, as the length-to-diameter aspect ratio L/D of the plug increases, the size of the core increases in comparison with all the fluid carried along with the ring, until the limiting case of Hill's spherical vortex is reached. For aspect ratios larger than a certain value it is not possible to produce a single ring while conserving circulation, impulse, volume and energy. This implies that the limiting vortex is ‘optimal’ in the sense that it has maximum impulse, circulation and volume for a given energy input. While this matching calculation makes the physical mechanism clear, the L/D ratio that can be achieved in practice is more appropriately taken from the direct experimental measurements of Gharib et al. (1998) who concluded that the limiting value is L/D = 4. This is close to the value found in our calculation.
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Si, Yaping, and Royal D. Heins. "Influence of Day and Night Temperature on Development of Sweet Pepper Seedlings." HortScience 30, no. 4 (July 1995): 862B—862. http://dx.doi.org/10.21273/hortsci.30.4.862b.
Full textAbstract:
Sweet pepper (Capsicum annuum `Resistant Giant #4') seedlings were grown in 128-cell plug trays under 16 day/night temperature (DT/NT) regimes from 14 to 26C. In this temperature range, plant stem height, leaf unfolding rate, plant volume, internode length, stem diameter, leaf area, and shoot dry weight were primarily functions of average daily temperature (ADT). Internode length increased as ADT or the difference between day and night temperature (DIF) increased. The root-to-shoot ratio decreased linearly as DT increased and was not significantly affected by NT. Leaves were darker green under positive DIF than negative DIF temperature regimes. Increasing NT from 14 to 26C reduced the node at which the first flower appeared by an average of 1.2 nodes. Percent abortion of the first flower increased as DT increased. Plant quality, as defined by seedling index [(dry weight × stem diameter)/internode length], increased as DIF became more negative.
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Liu, Haitao, Tian Huang, Jianping Mei, Xueman Zhao, Derek G. Chetwynd, Meng Li, and S. Jack Hu. "Kinematic Design of a 5-DOF Hybrid Robot with Large Workspace/Limb–Stroke Ratio." Journal of Mechanical Design 129, no. 5 (May 26, 2006): 530–37. http://dx.doi.org/10.1115/1.2712220.
Full textAbstract:
This paper deals with the conceptual and kinematic designs of a 5-degree of freedom (DOF) reconfigurable hybrid robot. The robot is composed of a 2-DOF parallel spherical mechanism that is serially connected with a 3-DOF open loop kinematic chain via a prismatic joint. Somewhat similar to the well-known Tricept robot, this design has the merit that a relatively large workspace/limb–stroke ratio can be achieved thanks to the decomposition of the motions of the output link into the 2-DOF rotation and 1-DOF translation. As with the Tricept, the robot is well suited for use as a plug-and-play module to configure different machines. The dimensional synthesis of the 2-DOF spherical parallel mechanism is carried out by the monotonical analysis of the design variables versus a global conditioning index represented by the mean of the minimum singular value of the Jacobian, leading to the solution of two nonlinear equations due to the limb length constraint and nearly axial symmetry requirement of the kinematic performance. The results of the dimensional synthesis are given via examples.
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Vollertsen, J., K. H. Lange, J. Pedersen, P. Hallager, A. Bruus, A. Laustsen, V. W. Bundesen, et al. "Monitoring the startup of a wet detention pond equipped with sand filters and sorption filters." Water Science and Technology 60, no. 4 (April 1, 2009): 1071–79. http://dx.doi.org/10.2166/wst.2009.460.
Full textAbstract:
The startup of a wet retention pond designed for extended stormwater treatment was monitored by more than one year of continual measurement of hydraulic parameters, nutrients and quality parameters in the pond itself (pH, temperature, dissolved oxygen, turbidity). The data revealed that photosynthesis played an important role for dissolved oxygen and pH for most of the year. Another important observation was that the pond behaved more like a completely mixed reactor than like a plug flow reactor—even though the length to width ratio was as high as 4.5:1. The pond was equipped with sand filters and sorption filters whereby very good nutrient removal efficiencies were achieved.
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Wong, Harris, C. J. Radke, and S. Morris. "The motion of long bubbles in polygonal capillaries. Part 2. Drag, fluid pressure and fluid flow." Journal of Fluid Mechanics 292 (June 10, 1995): 95–110. http://dx.doi.org/10.1017/s0022112095001455.
Full textAbstract:
This work determines the pressure–velocity relation of bubble flow in polygonal capillaries. The liquid pressure drop needed to drive a long bubble at a given velocity U is solved by an integral method. In this method, the pressure drop is shown to balance the drag of the bubble, which is determined by the films at the two ends of the bubble. Using the liquid-film results of Part 1 (Wong, Radke & Morris 1995), we find that the drag scales as Ca2/3 in the limit Ca → 0 (Ca μU/σ, where μ is the liquid viscosity and σ the surface tension). Thus, the pressure drop also scales as Ca2/3. The proportionality constant for six different polygonal capillaries is roughly the same and is about a third that for the circular capillary.The liquid in a polygonal capillary flows by pushing the bubble (plug flow) and by bypassing the bubble through corner channels (corner flow). The resistance to the plug flow comes mainly from the drag of the bubble. Thus, the plug flow obeys the nonlinear pressure–velocity relation of the bubble. Corner flow, however, is chiefly unidirectional because the bubble is long. The ratio of plug to corner flow varies with liquid flow rate Q (made dimensionless by σa2/μ, where a is the radius of the largest inscribed sphere). The two flows are equal at a critical flow rate Qc, whose value depends strongly on capillary geometry and bubble length. For the six polygonal capillaries studied, Qc [Lt ] 10−6. For Qc [Lt ] Q [Lt ] 1, the plug flow dominates, and the gradient in liquid pressure varies with Q2/3. For Q [Lt ] Qc, the corner flow dominates, and the pressure gradient varies linearly with Q. A transition at such low flow rates is unexpected and partly explains the complex rheology of foam flow in porous media.
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Kitaya, Yoshiaki, Genhua Niu, Maki Ohashi, and Toyoki Kozai. "Effects of Photosynthetic Photon Flux, Photoperiod, and CO2 Enrichment on the Growth and Morphogenesis of Lettuce Plug Transplants." HortScience 32, no. 3 (June 1997): 542E—543. http://dx.doi.org/10.21273/hortsci.32.3.542e.
Full textAbstract:
Artificial lighting is widely used in controlled environment plant production to enhance plant growth and quality. However, high light intensity with artificial lighting is costly, and often causes increase of leaf temperature and, thus, leaf burn. We investigated the effects of photosynthetic photon flux (PPF) and photoperiod on the growth and morphogenesis of lettuce plug transplants under ambient and enriched CO2 levels. Three days after seeding, the plants were cultured under four PPF levels (100, 150, 200, and 300 μmol·m–2·s–1), two photoperiods (16 and 24 hr), and two CO2 levels (400 and 800 μmol·mol–1) for 18 days in growth chambers. Light source was fluorescent lamps. The air temperature around the plants was kept at 20°C. The results showed that dry weight of the plants increased linearly as PPF and daily integrated PPF (product of PPF and photoperiod) increased under both CO2 levels. At the same daily integrated PPF, higher CO2 level and longer photoperiod led to higher dry weight of the plants. CO2 enrichment increased significantly dry weight of the plants. The ratio of T/R and specific leaf area of the plants decreased quadratically as daily integrated PPF increased under both CO2 levels. The ratio of leaf length to leaf width of the plants decreased quadratically as PPF increased under the two photoperiods and CO2 levels.
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Runkle, Erik S., and Royal D. Heins. "254 Stem Extension and Subsequent Flowering of Plugs Grown Under A Far-red-deficient Film." HortScience 35, no. 3 (June 2000): 435A—435. http://dx.doi.org/10.21273/hortsci.35.3.435a.
Full textAbstract:
Environments with a low red (R, 600 to 700 nm) to far-red (FR, 700 to 800 nm) ratio (e.g., with high plant density) promote stem elongation, and a high R: FR suppresses it. While FR light promotes stem extension, it is also required for rapid, uniform flowering of many long-day plants. We investigated how a new FR filter [creating a FR-deficient (FRd) environment] influenced plug growth and subsequent flowering of pansy (Viola ×wittrockiana `Crystal Bowl Yellow'), petunia (Petunia ×hybrida `Carpet Pink'), impatiens (Impatiens wallerana `Accent Rose'), snapdragon (Antirrhinum majus `Liberty Scarlet'), and tomato (Solanum lycopersicon `Beefmaster'). One-week-old seedlings were placed under three filter treatments with 16-h photoperiods: the FRd filter, a neutral-density filter (N) that transmitted a similar PPF, and transferring plugs from the N to the FRd filter when leaves of each species began to touch (7 to 11 days later). The predicted phytochrome photoequilibria under the FRd and N filters was 0.80 and 0.72, respectively. After 25 to 35 days at 20 °C, node number and stem (or petiole for pansy) length were collected. Twenty plants of each species and filter treatment were then transferred to 4-inch pots and grown under natural photoperiods (14 to 15 h) at 20 °C until flowering. Compared to plants continually under the N filter, stem length under the FRd filter was significantly reduced in impatiens (by 11%), pansy (by 18%), petunia (by 34%), snapdragon (by 5%), and tomato (by 24%). Flowering of plants from plugs under the FRd filter was delayed by 2 to 3 days for snapdragon, petunia, and pansy. Filter treatment of plugs had no significant effect on flower number or plant height at flower.
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Yoo, Dong-Lim, and Seung-Woo Lee. "634 Effects of Light Sources for Light Period Extension on Growth and Fowering in Statice." HortScience 35, no. 3 (June 2000): 507A—507. http://dx.doi.org/10.21273/hortsci.35.3.507a.
Full textAbstract:
This experiment was conducted to investigate the effects of artificial light sources for light period extension on growth and flowering of statice `Sophia' and `Early Blue'. The seeds were sown on 10 June in a plug tray with 128 plugs. The seedlings were grown at the highland (800 m above sea level) for 50 days, and transplanted on 30 July in 20-cm-diameter plastic pots. High-pressure sodium lamps (HPS) (220V, 400W), incandescent lamps (Il) (220V, 200W), and fluorescent lamps (Fl) (220V, 40W) for day length extension (16-h photoperiod) as compared with short day (8-h photoperiod) were tested. HPS gave the greatest photosynthetically active radiation (PAR), but Fl did the smallest. HPS or Fl as compared with Il showed high ratio of red/far-red light. The leaves of plant grown under HPS were effective for light absorbance and chlorophyll contents. HPS promoted photosynthesis as much as light period extension, while more respiration than photosynthesis occurred under Fl affected by low PAR. Long day condition as light period extension hastened flowering of statice, and HPS or Il were more effective than Fl on flowering among artificial light sources tested. The light compensation and saturation points of statice were 50 and 500 μmol·m–2·s–1, respectively. Photosynthesis hastened at high temperature, but amount of photosynthesis at vegetative stage showed much higher than flowering stage under the condition below 20 °C These results indicated that day length extension with HPS increased productivity and quality for cut flower of statice at the highland in Korea.
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Yeung, Hoi. "Modelling of service reservoirs." Journal of Hydroinformatics 3, no. 3 (July 1, 2001): 165–72. http://dx.doi.org/10.2166/hydro.2001.0016.
Full textAbstract:
Service reservoirs were built to provide the dual function of balancing supply with demand and provision of adequate head to maintain pressure throughout the distribution network. Changing demographics in the UK and reducing leakage have led to significant increases in water age and hence increased risk of poor water quality. Computational fluid mechanics has been used to study the behaviour of a range of service reservoirs with a rectangular plan form. Detailed analysis of flow distribution and water age suggests that tanks with horizontal inlets are better mixed when compared with vertical top water level inlets. With increasing length to width ratio, the flow characteristics of tanks with vertical inlets increasingly resemble plug flow. A new multi-channel reactor model was developed to model the recirculations in service reservoirs. This simple model can be used to characterise the flow characteristics of service reservoirs from tracer test results.
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Li, Jianzhong, Jian Chen, Li Yuan, and Ge Hu. "Effect of Airflow Temperature on the Formation of Initial Flame Kernel and the Propagation Characteristics of Flame." International Journal of Aerospace Engineering 2018 (December 17, 2018): 1–12. http://dx.doi.org/10.1155/2018/7286705.
Full textAbstract:
Using liquid RP-3 aviation kerosene as the fuel to study, the effect of airflow temperature on the formation of initial flame kernel during the ignition of spray combustion and on the propagation characteristics of flame was investigated. Combining high-speed camera and dynamic temperature acquisitions at the outlet of combustor, the internal triggering mode was used under a constant fuel flow rate and airflow velocity. This combined system simultaneously recorded the formation of initial flame kernel, flame propagation, and outlet temperature variation of combustor under different airflow temperatures. MATLAB software was used to obtain the reaction zones at different moments and to analyze the effects of airflow temperature on morphological characteristics such as flame area, perimeter-to-area ratio, maximum length-to-height ratio, equivalent mean length-to-height ratio, mass center, and centroid. According to the growth rate in flame area, the ignition process can be divided into three stages: formation of flame kernel, rapid development of flame, and stable development of flame. Airflow temperature not only affects the formation time of flame kernel but also affects the growth rate of flame area. During the development of flame, the movements of mass center and centroid are irregular, and their positions do not coincide with each other. However, the overall moving trends are consistent. With the increase of the airflow temperature, the position, where the flame kernel is gradually formed, moves closer to the center of the end face of spark plug. The force of airflow on flame is the main factor that increases the flame area and heat-release rate. Therefore, the folds around the flame edge mainly result from the stretching under the action of airflow. With the increase in airflow temperature, the heat release of the initial flame kernel increases, and the ratio of perimeter to area as a characterization parameter increases by 8%, 86%, and 33%, respectively. In addition, the maximum outlet temperature rise increased by about 53%, 73.5%, and 0.65%, respectively. Meanwhile, the maximum rate of temperature rise increased by about 42.8%, 57%, and 5.1%, respectively.
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Takriff, Mohd Sobri, and Zuhrina Masyitah. "Application 0f Draft Tube in the Reduction of Backmixing Rate in Oscillatory Flow in a Baffled Column." ASEAN Journal of Chemical Engineering 2, no. 1 (October 20, 2008): 15. http://dx.doi.org/10.22146/ajche.50798.
Full textAbstract:
Oscillatory flow in a baffled tube/column is an efficient way to enhance mixing in a straight smooth column. However, liquid oscillation moving back and forth across the baffle causes backmixing which is a disadvantage when plug flow is desired. This paper presents results from a study conducted to reduce the backmixing rate in oscillatory flow in a baffled column with the use of a draft tube. Results of this study showed that backmixing increases with oscillation velocity and decreases with liquid flow rate. The use of a draft tube reduces backmixing. The backmixing reduction is proportional to the ratio of L/Do However, the draft tube can not be extended too long because it disrupts the flow behavior in the column and creates dead zones near the baffle region. The draft tube length is maximized by extending it to both sides of the baffle, provided that the L/De on each side of the baffle is at 0.67 or less.
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ÖZDEMİR, Emine, Nurettin KAŞKA, Kazim GÜNDÜZ, and Sedat SERÇE. "Effects of Short Day Conditioning, Chilling and GA3 Treatments to Yield and Fruit Quality in Strawberry Plug Transplants Aiming Early Fruit Production." Notulae Botanicae Horti Agrobotanici Cluj-Napoca 41, no. 1 (May 28, 2013): 263. http://dx.doi.org/10.15835/nbha4119018.
Full textAbstract:
In this study, we tested the effects of short day (SD), chilling (Ch) and gibberalic acid (GA3) treatments on the yield and fruit characteristics of ‘Camarosa’ and ‘Sweet Charlie’ plug plants under a freeze-protected greenhouse in Mediterranean conditions for two growing seasons in 2006-2007 and 2007-2008. The treatments included control (ambient day length and temperature); SD (8 h days) and ambient temperature; SD + Chilling (Ch) (18/12°C day/night temperatures); SD + Ch (10°C); SD + Ch (2°C); and, GA3 (10 ppm applied to the plants in November). In each growing season, the plug plants were planted in mid-August using bag culture. Yield, fruit weight, firmness, total soluble solids (SS), titratable acidity (TA), and SS/TA ratio were investigated. Considerable amounts of early yield (March and April) were recovered from ‘Sweet Charlie’; 116 and 72 g/plant in the first and second growing seasons, respectively. ‘Sweet Charlie’ also had consistently higher total yield than ‘Camarosa’ (457 vs. 400 g/plant in the 2006-2007 season and 446 vs. 406 g/plant in the 2007-2008 season). Treatment did not have a consistent effect on the fruit quality traits measured. The results indicated that although SD conditioning, Ch and GA3 treatments may have an effect on the total and early yield of strawberries, these effects may be cultivar-dependent and further regulated by environmental factors. Therefore, we propose that low-chilling varieties be utilized for early fruit production that can initiate flower buds in warmer, longer days.
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Imqam, Abdulmohsin, Ze Wang, and Baojun Bai. "Preformed-Particle-Gel Transport Through Heterogeneous Void-Space Conduits." SPE Journal 22, no. 05 (March 22, 2017): 1437–47. http://dx.doi.org/10.2118/179705-pa.
Full textAbstract:
Summary Preformed particle gels (PPGs) have been successfully applied as a plugging agent to solve the conformance problem in fractured reservoirs. They are injected to plug fractures and then divert displacing fluid into poorly swept zones/areas. However, PPG-propagation and -plugging mechanisms through open void-space conduits (VSCs) have not been studied thoroughly. This paper investigated various situations involving heterogeneous conduits and their geometrical effect on PPG injectivity. Five-foot tubes were used to mimic VSCs. Three models were designed to gain understanding on how conduit geometry and PPG properties affect gel transportation, including a single conduit with a uniform internal diameter (ID); a single conduit with a nonuniform ID along its length; and two parallel conduits with different ID ratios with respect to each other. Results obtained from single-conduit models with uniform and nonuniform diameters showed PPG-injection pressure increased significantly as the conduit became more heterogeneous. Particle gels accumulated at the choke point within each conduit and caused injection pressure to increase accordingly. When two parallel conduits are available for flow, the relative distance of PPG penetration into the conduits depends strongly on the ratio of the conduit diameters and the gel strength. In addition, the ratio of gel-particle-size diameter to conduit diameter contributes significantly to the gel-transport selection. This paper demonstrates important impact elements of gel propagation for different heterogeneous-conduit situations.
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Lecampion, Brice, and Dmitry I. Garagash. "Confined flow of suspensions modelled by a frictional rheology." Journal of Fluid Mechanics 759 (October 22, 2014): 197–235. http://dx.doi.org/10.1017/jfm.2014.557.
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AbstractWe investigate in detail the problem of confined pressure-driven laminar flow of neutrally buoyant non-Brownian suspensions using a frictional rheology based on the recent proposal of Boyer et al. (Phys. Rev. Lett., vol. 107 (18), 2011, 188301). The friction coefficient (shear stress over particle normal stress) and solid volume fraction are taken as functions of the dimensionless viscous number $I$ defined as the ratio between the fluid shear stress and the particle normal stress. We clarify the contributions of the contact and hydrodynamic interactions on the evolution of the friction coefficient between the dilute and dense regimes reducing the phenomenological constitutive description to three physical parameters. We also propose an extension of this constitutive framework from the flowing regime (bounded by the maximum flowing solid volume fraction) to the fully jammed state (the random close packing limit). We obtain an analytical solution of the fully developed flow in channel and pipe for the frictional suspension rheology. The result can be transposed to dry granular flow upon appropriate redefinition of the dimensionless number $I$. The predictions are in excellent agreement with available experimental results for neutrally buoyant suspensions, when using the values of the constitutive parameters obtained independently from stress-controlled rheological measurements. In particular, the frictional rheology correctly predicts the transition from Poiseuille to plug flow and the associated particles migration with the increase of the entrance solid volume fraction. We also numerically solve for the axial development of the flow from the inlet of the channel/pipe toward the fully developed state. The available experimental data are in good agreement with our numerical predictions, when using an accepted phenomenological description of the relative phase slip obtained independently from batch-settlement experiments. The solution of the axial development of the flow notably provides a quantitative estimation of the entrance length effect in a pipe for suspensions when the continuum assumption is valid. Practically, the latter requires that the predicted width of the central (jammed) plug is wider than one particle diameter. A simple analytical expression for development length, inversely proportional to the gap-averaged diffusivity of a frictional suspension, is shown to encapsulate the numerical solution in the entire range of flow conditions from dilute to dense.
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Liu, Xuyang, Xuejun Bi, Qing Huang, Xiaodong Wang, Ruihuan Gu, and Xiaolin Zhou. "The Changing and Distribution Laws of Oxygen Transfer Efficiency in the Full-Scale IFAS Process." Water 13, no. 14 (July 13, 2021): 1933. http://dx.doi.org/10.3390/w13141933.
Full textAbstract:
The integrated fixed-film activated sludge (IFAS) process has been widely used in the upgrading of wastewater treatment plants (WWTPs). The oxygen transfer efficiency (αOTE) is of great significance to the design and operation of the IFAS process. The carrier filling ratio (CFR) and aeration type are two critical factors affecting αOTE and standard oxygen transfer efficiency (αSOTE). However, the distribution and changing laws of αOTE and αSOTE in the full-scale IFAS process areunclear. To optimize the operation of a WWTP and to improve the αOTE of the aeration systems, several off-gas tests were conducted under different aeration types and different CFRs. The results show that for the aerobic tank investigated (the ratio of length and width was 8:1), the αOTE and the αSOTE of the middle of the aeration systems were higher than those of the other two sides. However, the reason for the low αOTE at the beginning and the end of the tank may be different. Coarse-bubble aeration systems had a lower αOTE and almost the same oxygenation capacity (αSOTE) as the fine-bubble aeration systems under constant CFR (43%). The average αSOTE (18.7–28.9%) of the hybrid aeration systems increased with increasing CFR (7.7–57.7%), and different locations exhibited different degrees of change. The results reveal the distribution and changing law of the αOTE of aeration systems in the IFAS process, and attention should be paid to the improvement of the OTE of the plug-flow IFAS process.
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Huang, Qingqing, Xinbo Yang, and Rick Q. Honaker. "Evaluation of Frother Types for Improved Flotation Recovery and Selectivity." Minerals 9, no. 10 (September 28, 2019): 590. http://dx.doi.org/10.3390/min9100590.
Full textAbstract:
A laboratory study was conducted to evaluate and compare the effectiveness of nine different frother types when used in a three-phase, continuously operating froth flotation system. The frothers included several that are commonly used in the industry (e.g., MIBC, 2EH, and F-1) as well as unique frother types (e.g., F-3). The tests were conducted in a 5-cm diameter laboratory flotation column that provided near plug-flow mixing conditions due to a length-to-diameter ratio of around 50:1. Test results indicate that F-1, MIBC, and MPC (in order of decreasing effectiveness) provided the weakest performance in terms of combustible recovery while F-2, MAC, and 2EH were the top three generating the highest separation efficiencies. When processing ultrafine coal, the ash content of the flotation concentrate ranged from 10% to 15% while recovering over 80% of the combustible material. F-3, F-4, and DIBC provided over 80% recovery of combustibles at the expense in the amount of hydraulic entrainment. The flotation performances were also closely examined in accordance with the fundamental properties of the nine tested frothers, and their correlations were addressed in detail.
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Kumaran, V. "Dense shallow granular flows." Journal of Fluid Mechanics 756 (September 3, 2014): 555–99. http://dx.doi.org/10.1017/jfm.2014.412.
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AbstractSimplified equations are derived for a granular flow in the ‘dense’ limit where the volume fraction is close to that for dynamical arrest, and the ‘shallow’ limit where the stream-wise length for flow development ($\def \xmlpi #1{}\def \mathsfbi #1{\boldsymbol {\mathsf {#1}}}\let \le =\leqslant \let \leq =\leqslant \let \ge =\geqslant \let \geq =\geqslant \def \Pr {\mathit {Pr}}\def \Fr {\mathit {Fr}}\def \Rey {\mathit {Re}}L$) is large compared with the cross-stream height ($h$). The mass and diameter of the particles are set equal to 1 in the analysis without loss of generality. In the dense limit, the equations are simplified by taking advantage of the power-law divergence of the pair distribution function $\chi $ proportional to $(\phi _{ad} - \phi )^{- \alpha }$, and a faster divergence of the derivative $\rho (\mathrm{d} \chi / \mathrm{d} \rho ) \sim (\mathrm{d} \chi / \mathrm{d} \phi )$, where $\rho $ and $\phi $ are the density and volume fraction, and $\phi _{ad}$ is the volume fraction for arrested dynamics. When the height $h$ is much larger than the conduction length, the energy equation reduces to an algebraic balance between the rates of production and dissipation of energy, and the stress is proportional to the square of the strain rate (Bagnold law). In the shallow limit, the stress reduces to a simplified Bagnold stress, where all components of the stress are proportional to $(\partial u_x/\partial y)^2$, which is the cross-stream ($y$) derivative of the stream-wise ($x$) velocity. In the simplified equations for dense shallow flows, the inertial terms are neglected in the $y$ momentum equation in the shallow limit because the are $O(h/L)$ smaller than the divergence of the stress. The resulting model contains two equations, a mass conservation equations which reduces to a solenoidal condition on the velocity in the incompressible limit, and a stream-wise momentum equation which contains just one parameter $\mathcal{B}$ which is a combination of the Bagnold coefficients and their derivatives with respect to volume fraction. The leading-order dense shallow flow equations, as well as the first correction due to density variations, are analysed for two representative flows. The first is the development from a plug flow to a fully developed Bagnold profile for the flow down an inclined plane. The analysis shows that the flow development length is $(\bar{\rho }h^3 / \mathcal{B})$, where $\bar{\rho }$ is the mean density, and this length is numerically estimated from previous simulation results. The second example is the development of the boundary layer at the base of the flow when a plug flow (with a slip condition at the base) encounters a rough base, in the limit where the momentum boundary layer thickness is small compared with the flow height. Analytical solutions can be found only when the stream-wise velocity far from the surface varies as $x^F$, where $x$ is the stream-wise distance from the start of the rough base and $F$ is an exponent. The boundary layer thickness increases as $(l^2 x)^{1/3}$ for all values of $F$, where the length scale $l = \sqrt{2 \mathcal{B}/ \bar{\rho }}$. The analysis reveals important differences between granular flows and the flows of Newtonian fluids. The Reynolds number (ratio of inertial and viscous terms) turns out to depend only on the layer height and Bagnold coefficients, and is independent of the flow velocity, because both the inertial terms in the conservation equations and the divergence of the stress depend on the square of the velocity/velocity gradients. The compressibility number (ratio of the variation in volume fraction and mean volume fraction) is independent of the flow velocity and layer height, and depends only on the volume fraction and Bagnold coefficients.
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Meng, Hui-Bo, Wei Wang, Yan-Fang Yu, Jian-Hua Wu, Yan-Fen Wang, and Zong-Yong Wang. "Investigation of the Effect of Outlet Structures on the Jet Flow Characteristics in the Circulating Jet Tank." International Journal of Chemical Reactor Engineering 12, no. 1 (January 1, 2014): 35–45. http://dx.doi.org/10.1515/ijcre-2013-0125.
Full textAbstract:
Abstract A revised numerical model of circulating jet tank (CJT) was constructed by adding four momentum sources. The radial distribution tendency of total pressure predicted by large eddy simulation had a good agreement with experimental results. The axial velocities at the center of downcomers have parabolic attenuation tendency with the increasing axial positions. The inductive and restrictive effects of outlets on the jet flow performances were evaluated by the parameters, such as jet velocity decay, spreading rate and energy dissipation. The optimum factor of outlet structures was proposed based on the ratio of spreading rate to energy dissipation. Numerical results show that the downcomers equipped with four symmetrical rectangular outlets contribute more to reduce the decay of jet centerline velocity and make good use of the entrainment between the jet and bulk liquid to generate the largest spreading rate. Furthermore, a nearly plug flow pattern and the maximum value of optimum factor are attained compared with other types of outlets. The optimum factors of rectangular outlets firstly increase then decrease with the increasing ratios of width to diameter of the downcomers. Rectangular outlets induce the jet to expand and get the largest dimensionless jet length and spreading rate when the ratios of width to diameter w/D1 approach 0.08.
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Kou, Hai-Lei, Wen-Zhou Diao, Tao Liu, Dan-Liang Yang, and Suksun Horpibulsuk. "Field Performance of Open-Ended Prestressed High-Strength Concrete Pipe Piles Jacked into Clay." Sensors 18, no. 12 (December 1, 2018): 4216. http://dx.doi.org/10.3390/s18124216.
Full textAbstract:
The behavior of open-ended pipe piles is different from that of closed-ended pipe piles due to the soil plugging effect. In this study, a series of field tests were conducted to investigate the behavior of open-ended prestressed high-strength concrete (PHC) pipe piles installed into clay. Two open-ended PHC pipe piles were instrumented with Fiber Bragg Grating (FBG) sensors and jacked into clay for subsequent static loading tests. Soil plug length of the test piles was continuously measured during installation, allowing for calculation of the incremental filling ratio. The recorded data in static loading test were reported and analyzed. The distribution of residual forces after installation and the effect on the bearing capacity were also discussed in detail. The test piles were observed to be in partially plugged condition during installation. The measured ultimate shaft resistance and total resistance of the test piles were 639 and 1180 kN, respectively. The residual forces locked in the test piles after installation significantly affected the evaluation of the axial forces, and thus the shaft and end resistances. It tended to underestimate the end resistances and overestimate the shaft resistances if the residual forces were not considered in the loading test. However, the residual forces did not affect the total bearing capacity of open-ended PHC pipe piles in this study.
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Zheng, Jinjian, and Edward S. Yeung. "Counting Single DNA Molecules in a Capillary with Radial Focusing." Australian Journal of Chemistry 56, no. 3 (2003): 149. http://dx.doi.org/10.1071/ch02192.
Full textAbstract:
For single-molecule detection, usually a small detection volume of 10 pL or less is used to improve the signal-to-noise ratio. Detection of every molecule in a sample requires that the sample be driven through a well-defined volume to facilitate laser excitation. We report a novel approach to count single DNA molecules with nearly 100% efficiency. By applying an electric field across a 40 cm long, 75 × 75 µm2 square capillary together with hydrodynamic flow from cathode to anode, we were able to concentrate more than 95% of DNA molecules into a 10 µm region at the centre of the capillary. The YOYO-1 labelled λ-DNA molecules were imaged with an intensified CCD camera. We found that the single DNA molecule detection efficiency in a 10–17 M solution was 114 ± 21%. The mobility of the DNA molecules after radial focusing was relatively constant, with relative standard deviations ranging from 0.8% to 1.4%. This allowed us to match the sampling rate to the length of the detection window to maximize counting efficiency. Analysis of a 40.2 nL injected plug of 2 × 10–14 M λ-DNA gave a result of 492 ± 73 molecules, which agreed well with the estimated value of 484. This method should be generally useful for counting deformable molecules or non-spherical particles at extremely low concentrations.
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Tüzel, Yüksel, Kamil Ekinci, Gölgen Bahar Öztekin, İbrahim Erdal, Nurhan Varol, and Özen Merken. "Utilization of Olive Oil Processing Waste Composts in Organic Tomato Seedling Production." Agronomy 10, no. 6 (June 4, 2020): 797. http://dx.doi.org/10.3390/agronomy10060797.
Full textAbstract:
Olive oil byproducts show differences according to the olive oil extraction systems, which are called olive mill solid wastes, olive oil wastewater and olive oil wastewater sludge. Three different kinds of composts, including two-phase and three-phase olive mill solid wastes, and olive oil wastewater sludge were produced with separated dairy manure, poultry manure, and straw. The composts obtained from two-phase and three-phase olive mill solid wastes and olive oil wastewater sludge were named as two-phase, three-phase, and water sludge composts, respectively. They were separately enriched by rock phosphate and potassium salt. These composts were mixed with peat in a ratio of 0%, 25%, 50%, 75%, and 100% (v/v). Tomato seeds were sown in all mixtures on 3 February 2016. All the seeds were sown into 2 trays and each plug included 2 replicates. The trays were left in a germination room for 3 days, then moved to a heated greenhouse which is specialized for growing seedlings, and the seedlings were grown there for 3 weeks. The results showed that increasing compost ratios in the growing medium and also the enrichment of the growing medium increased organic matter content, electrical conductivity, and macro and micro nutrient concentrations. The germination period lasted longer with increasing compost ratios. The shoot length was lower at a compost ratio of over 50% excluding water sludge compost, which reacted to over 75%. The highest plant dry weights were obtained in the plants grown on the media with compost ratios of 50%, 25%, and 25% for water sludge compost, enriched two-phase compost, and enriched three-phase compost, respectively. We concluded that the composts obtained from two-phase and three-phase olive mill solid wastes and olive oil waste water sludge can be used without any need of enrichment and a ratio of 25% was found appropriate in most of the measured properties.
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Varela, C. Pintos, V. Redondo Fernández, O. Aguín Casal, and J. P. Mansilla Vázquez. "First Report of Cankers and Dieback Caused by Neofusicoccum mediterraneum and Diplodia corticola on Grapevine in Spain." Plant Disease 95, no. 10 (October 2011): 1315. http://dx.doi.org/10.1094/pdis-05-11-0429.
Full textAbstract:
In November 2010, four grapevine plants of cv. Crimson from a vineyard located in Sevilla (south Spain) revealed trunk cankers. Several pathogens were isolated, including Cylindrocarpon liriodendri (2), Phaeoacremonium aleophilum (2), Pleurostomophora richardsiae, Neofusicoccum parvum, and Botryosphaeria dothidea (2). Among Botryosphaeriaceae fungi isolated on potato dextrose agar (PDA) were two types that did not fit the above mentioned species. Isolates of type 1 produced an abundant, gray mycelium with a diurnal zonation that gradually became dark olivaceous. Mycelium growth occurred from 5 to 37°C with an optimum at 28°C. Conidia were hyaline, fusiform, aseptate, thin walled, but gradually became obscured and septate with age, and measured (18.4-) 21.4 (-24.3) × (4.2-) 5.5 (-7.2) μm with a length/width (L/W) ratio of 4.0 ± 0.5 (n = 100). Isolates of type 1 were identified as N. mediterraneum (3). Single-spore cultures of type 2 developed a whitish, dense, aerial mycelium and remained white up to 10 days on PDA and darkened to gray thereafter. Mycelium growth occurred from 3 to 37°C with an optimum at 29 to 30°C. Conidia were hyaline, aseptate, thick walled, oblong to cylindrical, sometimes becoming light brown and one or two septate after discharge, and measured (24.6-) 30.2 (-42.8) × (10.9-) 14.3 (-18.6) μm with a L/W ratio of 2.1 ± 0.2 (n =100). Isolates of type 2 were identified as Diplodia corticola (1). Nucleotide sequences of the ribosomal internal transcribed spacer (ITS) region and the -tubulin genes were used to confirm the identifications through BLAST searches in GenBank. Comparison of the sequences of types 1 and 2 showed 99 to 100% homology with N. mediterraneum (HM443604 (4) and GU251836) and D. corticola (AY268421 (1) and EU673117), respectively. Representative sequences of N. mediterraneum (JF949757 and JF949756) and D. corticola (JF949758 and JF949759) were deposited in GenBank. The pathogenicity of one representative isolate of each of N. mediterraneum and D. corticola was confirmed by inoculating 10 detached grapevine canes (averaging 12 mm in diameter and 30 cm long) per isolate. A shallow wound was made with a scalpel on the internodes. A colonized 6-mm agar plug, from the margin of an actively growing colony, was inserted in every wound and sealed with Parafilm. Ten grapevine canes controls received only sterile PDA agar plugs. Canes were maintained at 25°C and 70% humidity. After 5 weeks, all inoculated canes developed cankers and pycnidia around the inoculation site. Vascular necroses that developed on the inoculated canes were an average of 28.6 mm for N. mediterraneum and 27.7 mm for D. corticola. One-way analysis of variance and Tukey's test confirmed significant differences in the extent of vascular necroses. The average necroses length in the inoculated canes was significantly greater (P < 0.05) than the average length of discoloration induced by the simulated inoculation process in the control. Both pathogens were reisolated from all inoculated plants but not from controls. To our knowledge, this is the first report of N. mediterraneum and D. corticola as pathogens on grapevine in Spain. References: (1) A. Alves et al. Mycologia 96:603, 2004. (2) A. Aroca and D. Gramaje et al. Eur. J. Plant. Pathol. 126:165, 2010. (3) P. W. Crous et al. Fungal Planet. No. 19, 2007. (4) F. P. Trouillas et al. Plant. Dis. 94:1267, 2010.
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Wick, R. L., and M. B. Dicklow. "Epipremnum, a new host for Phytophthora capsici." Plant Disease 86, no. 9 (September 2002): 1050. http://dx.doi.org/10.1094/pdis.2002.86.9.1050b.
Full textAbstract:
From 1999 to 2001, a Massachusetts nursery received a number of shipments of Pothos, Epipremnum aureum (Lindl. & André) Bunting, with significant crown, petiole, and leaf rot. The plants were imported from Costa Rica. Sporangia were observed on diseased tissues, and five presumptive isolates of Phytophthora were recovered from infected petioles and stems for species identification. The five isolates were morphologically indistinguishable from each other. Sporangia were produced in water and on V8 juice agar under fluorescent light at 22°C. Mating type was determined by pairing isolates with A1 and A2 mating types of Phytophthora capsici Leonian. Sporangial measurements were taken from water cultures. Determination of caducity, and measurements of pedicels and oospores were taken from V8 agar cultures. Measurements represent an average of 50 observations a single isolate. In water culture, sporangia were borne in umbellate clusters. Sporangium length/breadth was 48.29 and 22.33 μm respectively; length/breadth ratio 2.16. On solid media, sporangia were upright and caducous. The bases of the sporangia were mostly tapered. Pedicel lengths were 22 to 49 μm (average 35 μm). Oogonia had amphigynous antheridia and developed only in the presence of an opposite mating type, and oospores measured 25.74 μm diameter. All five isolates were the A1 mating type. Chlamydospores were absent in V8 and corn meal agar (CMA) cultures. Metalaxyl sensitivity was determined at 0, 0.1, 0.5, and 5 ppm in CMA with five replications. The isolate was completely sensitive to 5 ppm metalaxyl, but grew as well as the controls at 0.1 ppm metalaxyl. Growth response to temperature was determined on V8 agar at 15, 20, 25, 30, and 35°C in five replications. After 4 days, colony diameters at 20, 25, and 30°C were not significantly different (P = 0.01) and colonies filled the 100-mm petri dishes. At 15 and 35°C, average colony diameter was 65.7 and 71.4 mm, respectively. Based on the above characteristics, the isolates were identified as P. capsici. Koch's postulates were carried out on pepper, Capsicum annuum ‘Italia’, squash, Cucurbita pepo ‘Patty Pan’ seedlings, and rooted cuttings of pothos. Pepper and squash seedlings and rooted pothos were transplanted in 4-in. (10 cm) pots containing a soilless growing medium (Metro Mix 360, W.R. Grace, Columbia, MD). Phytophthora cultures were grown on V8 juice agar for 4 days. An agar culture was added to 200 ml of sterile distilled water and briefly blended. Ten milliliters of the resulting mycelial slurry were pipetted in the soil one cm from the crown on two sides of the plant. Controls received no mycelial slurry. Petiole, leaf, and crown rot of pothos developed within 2 weeks following inoculation. Squash and pepper plants did not become diseased. In a second pathogenicity test, a 1-cm-diameter plug of mycelial growth from a V8 agar culture was placed between the stem and petiole of the lowest leaf of pothos cuttings directly after transplanting. Inoculated plants died within 3 days. The development of umbellate clusters of sporangia, sporangial shape, length/breadth ratio, and lack of pathogenicity to pepper suggest that the P. capsici isolated from pothos belong to the CAPB (tropical) subgroup of Mchau and Coffey (2). References: (1) S. S. A. Al-Hedaithy and P. H. Tsao. Mycologia 71:392, 1979. (2) G. R. Mchau. and M. D. Coffey. Mycol. Res. 99:89, 1995.
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Barnard, James L., Thomas E. Kunetz, and Joseph P. Sobanski. "Sixty-five-year old final clarifier performance rivals that of modern designs." Water Science and Technology 57, no. 8 (April 1, 2008): 1235–40. http://dx.doi.org/10.2166/wst.2008.224.
Full textAbstract:
The Stickney plant of the Metropolitan Wastewater Reclamation District of Greater Chicago (MWRDGC), one of the largest wastewater treatment plants in the world, treats an average dry weather flow of 22 m3/s and a sustained wet weather flow of 52 m3/s that can peak to 63 m3/s. Most of the inner city of Chicago has combined sewers, and in order to reduce pollution through combined sewer overflows (CSO), the 175 km Tunnel and Reservoir Plan (TARP) tunnels, up to 9.1 m in diameter, were constructed to receive and convey CSO to a reservoir from where it will be pumped to the Stickney treatment plant. Pumping back storm flows will result in sustained wet weather flows over periods of weeks. Much of the success of the plant will depend on the ability of 96 circular final clarifiers to produce an effluent of acceptable quality. The nitrifying activated sludge plant is arranged in a plug-flow configuration, and some denitrification takes place as a result of the high oxygen demand in the first pass of the four-pass aeration basins that have a length to width ratio of 18:1. The SVI of the mixed liquor varies between 60 and 80 ml/g. The final clarifiers, which were designed by the District's design office in 1938, have functioned for more than 65 years without major changes and are still producing very high-quality effluent. This paper will discuss the design and operation of these final clarifiers and compare the design with more modern design practices.
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Wei, Hao, Chen Liu, and Byoung Ryong Jeong. "An Optimal Combination of the Propagation Medium and Fogging Duration Enhances the Survival, Rooting and Early Growth of Strawberry Daughter Plants." Agronomy 10, no. 4 (April 12, 2020): 557. http://dx.doi.org/10.3390/agronomy10040557.
Full textAbstract:
Runner propagation is an important process in strawberry cultivation, which influences plant survival and fruit yield during the commercial production. In South Korea, this process is carried out on plug tray benches that are set off the ground in greenhouses, rather than in open fields. During the propagation, the propagation media and fogging systems play an important role in the survival and rooting of daughter plants. The aim of this study is to investigate the influences of the different types of propagation media and various fogging treatments on the rooting and early growth of strawberry daughter plants. Two strawberry cultivars—‘Maehyang’ and ‘Seolhyang’—in a glasshouse, grown in four different propagation media-a peat moss-based mixture (PBM), rockwool cube (RWC), granular rockwool (GRW), and a coir-based mixture (CBM)—combined with five fogging durations, 0, 3, 6, 9 and 12 days were tested. PBM with 9–12 days of fogging was the most ideal combination for the rooting and early growth of daughter plants of the two strawberry cultivars, which increased the ratio of survival and rooting, number of new leaves, root length and maximised the fresh and dry weights of the aboveground and belowground runner biomass. However, fogging treatments shorter than 9 days led to a lower survival rate and rooting. RWC and GRW are not recommended for young plants of these two strawberry cultivars because their strong water-retentive properties could subject the root to water stress, which can lead to root rotting. The purpose of this study is to provide a reference for strawberry growers to improve the quality of plants and efficiency of production during the propagation period.
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Hejna, M., K. Cerny, L. Havrdova, and M. Mrazkova. "First Report of Phytophthora hedraiandra Causing Rhododendron Dieback and Root Rot of Common Beech in the Czech Republic." Plant Disease 98, no. 10 (October 2014): 1434. http://dx.doi.org/10.1094/pdis-04-14-0339-pdn.
Full textAbstract:
From 2010 to 2012, Phytophthora isolates were obtained from brownish diffusion leaf lesions usually up to 2 to 3 cm in diameter of Rhododendron caucasicum ‘Cheer,’ from withered twigs of Rhododendron sp. with blackish elongated lesions up to ~5 cm in length, and from rotten feeder roots of 2-year-old, chlorotic, wilting seedlings of Fagus sylvatica collected from ornamental and forest nurseries in three areas (central and eastern Bohemia and northern Moravia) in the Czech Republic. Isolates formed chrysanthemum-like to slightly stellate, appressed colonies with sparse aerial mycelium on V8 agar (V8A) plates at 20°C after 5 days, whereas on carrot agar (CA) plates the pattern was vague with no aerial mycelium. The cardinal growth temperatures were: min. 3°C, optimum 23 to 27°C, and max. 31°C. Radial growth was 5.7 to 6.6 mm/day at 20°C on V8A. The isolates were homothallic and produced colorless, smooth-walled, spherical oogonia with an average diameter 29.9 to 33.8 μm on CA. Oospores were aplerotic (avg. 26.4 to 29.3 μm), oospore wall was hyaline and averaged 1.3 to 1.7 μm thick, oospore wall index was 0.26 to 0.32. Paragynous or occasionally amphigynous antheridia averaged 13.4 to 15.0 × 10.9 to 12.5 μm (height × width). Sporangia were caducous, papillate, globose, spherical to ovoid, with short pedicels (avg. 2.1 to 2.6 μm) and averaged 30.9 to 41.5 × 25.5 to 30.6 μm, L:B ratio was 1.2 to 1.4. Chlamydospores were not observed. Morphological characters resembled those described for P. hedraiandra (1). The isolates were deposited in the collection of phytopathogenic oomycetes of RILOG Pruhonice and given accession nos. 450.11, 531.11, and 578.12. The isolates were sequenced for nuclear rDNA ITS region and partial Cox I gene. Obtained sequences were compared with sequences present in GenBank database using BLAST. The ITS sequences of all isolates (GenBank Accession Nos. KJ567081, 82, and 83) of overall length of 792 bp were identical to that of P. hedraiandra AY707987 (1). The Cox I sequences of overall length of 880 bp (KJ567084, 85, and 86) showed 99% homology (1 bp substitution) with AY769115 (1) and 100% identity with other Cox I sequences of P. hedraiandra, i.e., JN376067 (4) and EF174432 (3). Koch's postulates were confirmed by wound-inoculating of 3-year-old rhododendron and common beech plants (10 host plants per corresponding isolate). Rhododendron leaves were gently abraded near the midrib, whereas 5-mm-diameter bark plugs were removed from the beech collars. The inoculum (5-mm-diameter V8A plug with actively growing mycelium) was placed over wounds and sealed with Parafilm. Control plants were treated in the same manner with sterile agar plugs. Plants were maintained in a greenhouse at 22°C. All inoculated plants showed disease symptoms after 10 days of incubation; the lesions were up to 2 cm in rhododendron leaves and ~1 cm in beech collars. Control plants remained healthy. The pathogen was re-isolated from all infected plants. To our knowledge, this is the first report of P. hedraiandra in the Czech Republic. Besides it, the pathogen was found in southern and western Europe (Italy, Slovenia, Spain, the Netherlands) and in the United States (2). References: (1) A. W. A. M. de Cock and A. Lévesque. Stud. Mycol. 50:481, 2004. (2) D. F. Farr and A. Y. Rossman. Fungal Databases, Syst. Mycol. Microbiol. Lab., ARS, USDA. Retrieved from http://nt.ars-grin.gov/fungaldatabases/ , May 13, 2014. (4) E. Moralejo et al. Span. J. Agric. Res. 5:82, 2007. (2) X. Yang et al. Plant Dis. 96:915, 2012.
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Thomidis, T., and T. J. Michailides. "First Report of Stemphylium botryosum Causing Leaf Blight of Kiwi in the Province Imathia, Northern Greece." Plant Disease 92, no. 4 (April 2008): 650. http://dx.doi.org/10.1094/pdis-92-4-0650b.
Full textAbstract:
In Greece, kiwi (Actinidia deliciosa) is mostly found in the northern part of the country where approximately 440,000 ha are grown. In the summer of 2006, a Stemphylium sp. was frequently isolated from leaves of kiwi (cv. Hayward) grown in the province of Imathia. Symptomatic leaves were covered with irregular, necrotic, brown areas. Lesions had a distinct margin that, in some cases, covered a wide part of the diseased leaves. Intense symptoms were frequently observed and associated with defoliation. This Stemphylium sp. was consistently isolated from diseased leaves onto potato dextrose agar (PDA) after surface sterilization with 0.1% chlorine solution. On the basis of morphological characteristics of mycelia, dimensions (length 20 to 29 μm and width 14 to 21 μm) and mean length/width ratio (1.42 μm) of conidia, and width and apical cell width of condiophores, the fungus was identified as Stemphylium botryosum (Wallr.) (2,3) Koch's postulates were completed in the laboratory by inoculating leaves of kiwi (cv. Hayward) with an isolate of S. botryosum originated from a symptomatic leaf of a Hayward kiwi. Twenty leaves were surface sterilized by dipping them into 0.1% chlorine solution for 2 to 3 min, washing in sterile distilled water, and allowing them to dry in a laminar flow hood. A leaf was then placed into a petri plate containing a wet, sterilized paper towel. Inoculation was made by transferring a 5-mm-diameter mycelial disc from the margins of a 7-day-old culture onto the center of each leaf surface. Petri plates were closed and incubated at 25°C with 12 h of light for 6 days. Koch's postulates were satisfied when the same S. botryosum was reisolated from 100% of inoculated leaves that developed symptoms similar to those observed in the vineyards. Leaves inoculated with a PDA plug alone (with no S. botryosum) did not develop any symptoms. Previously, Alternaria alternata was reported as the causal agent of a leaf spot pathogen of kiwi (1,4). To our knowledge, this is the first report of the occurrence of S. botryosum causing leaf blight of kiwi in Greece and worldwide. This pathogen can cause a high level of defoliation in diseased plants. References: (1) L. Corazza et al. Plant Dis. 83:487, 1999. (2) M. B. Ellis. Dematiaceous Hyphomycetes. Mycology Institute. London, England, 1971. (3) E. G. Simmons. Mycologia 61:1, 1969. (4) C. Tsahouridou and C. C. Thanassoulopoulos. Plant Dis. 84:371, 2000
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Niilo-Rämä, Mikko, Salme Kärkkäinen, Dario Gasbarra, and Timo Lappalainen. "INCLUSION RATIO BASED ESTIMATOR FOR THE MEAN LENGTH OF THE BOOLEAN LINE SEGMENT MODEL WITH AN APPLICATION TO NANOCRYSTALLINE CELLULOSE." Image Analysis & Stereology 33, no. 2 (June 19, 2014): 147. http://dx.doi.org/10.5566/ias.v33.p147-155.
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A novel estimator for estimating the mean length of fibres is proposed for censored data observed in square shaped windows. Instead of observing the fibre lengths, we observe the ratio between the intensity estimates of minus-sampling and plus-sampling. It is well-known that both intensity estimators are biased. In the current work, we derive the ratio of these biases as a function of the mean length assuming a Boolean line segment model with exponentially distributed lengths and uniformly distributed directions. Having the observed ratio of the intensity estimators, the inverse of the derived function is suggested as a new estimator for the mean length. For this estimator, an approximation of its variance is derived. The accuracies of the approximations are evaluated by means of simulation experiments. The novel method is compared to other methods and applied to real-world industrial data from nanocellulose crystalline.
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Martin, M. T., L. Martin, M. J. Cuesta, and P. García-Benavides. "First Report of Cylindrocarpon pauciseptatum Associated with Grapevine Decline from Castilla y León, Spain." Plant Disease 95, no. 3 (March 2011): 361. http://dx.doi.org/10.1094/pdis-10-10-0750.
Full textAbstract:
During a survey for grapevine decline, 10 young grapevines (cvs. Tempranillo and Verdejo) with low vigor and little foliage were collected between June 2008 and August 2009. Small pieces of vascular and brown wood were placed onto malt extract agar supplemented with 0.25 g/liter of chloramphenicol and incubated at 25°C. Fifteen resulting colonies were transferred to potato dextrose agar in petri dishes (90 mm). Colonies with white mycelium covered the dishes after 10 days of incubation at 25°C in darkness; mycelium gradually became yellowish with some brownish aspect. Macroconida were predominantly three septate (40 to 45 to 50 × 8.6 to 9 to 9.5 μm with a length and width ratio of 4.7 to 5 to 5.4), straight, and cylindrical with both ends broadly rounded. Chlamydospora and ovoidal microconidia were observed on synthetic nutrient-poor agar (1). Cylindrocarpon pauciseptatum was not easy to distinguish from other Cylindrocarpon species based on morphological characteristics. Ribosomal internal transcribed spacer region sequences of single-spore cultures confirmed the morphological identification and revealed 100% genetic identity with other isolates of C. pauciceptatum present in GenBank (EF607090), a sequence of the fragment was deposited with Accession No. EU983277. Pathogenicity tests were conducted with two isolates. The inoculations were done on 110R rootstock wood of four different young plants and 15 detached canes of current-season growth (cv. Tempranillo). Plants were inoculated with an agar plug containing C. pauciceptatum; controls were treated with agar only. Grapevines were maintained in a greenhouse at 20 to 25°C. After 3 to 4 months, C. pauciceptatum was reisolated from brown tissues and internal vascular lesions in 45% of inoculated samples, fulfilling Koch's postulates. Control plants were asymptomatic and C. pauciceptatum was not recovered. To our knowledge, this is the first report implicating C. pauciceptatum as a cause of grapevine black foot disease in Spain with potentially significant impact on grapevine nurseries. Reference: (1) H. J. Schroers et al. Mycol. Res. 112:82, 2008.
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Willems, H., and R. Sierens. "Modeling the Initial Growth of the Plasma and Flame Kernel in SI Engines." Journal of Engineering for Gas Turbines and Power 125, no. 2 (April 1, 2003): 479–84. http://dx.doi.org/10.1115/1.1501912.
Full textAbstract:
The initial size and growth of the plasma and flame kernel just after spark discharge in S.I. engines determines if the flame becomes self-sustainable or extinguishes. On the other hand, the development of the kernel during the initial phases has non-negligible influences on the further combustion. For example, cyclic variations often find their origin in the beginning of combustion and determine the working limits of the engine and the driving behavior of the vehicle. These factors demonstrate the crucial importance of the knowledge of the initial growth of the plasma and flame kernel in S.I. engines. A complete model is developed for the growth of the initial plasma and flame kernel in S.I. engines, which takes into account the fundamental properties of the ignition system (electrical energy and power, geometry of the spark plug, heat losses to the electrodes and the cylinder wall), the combustible mixture (pressure, temperature, equivalence ratio, fraction of residual gasses, kind of fuel), and the flow (average flow velocity, turbulence intensity, stretch, characteristic time and length scales). The proposed model distinguishes three phases: the pre-breakdown, the plasma, and the initial combustion phase. The model of the first two phases is proposed in a previous article of the same authors [1], the latter is exposed in this article. A thermodynamic model based on flamelet models and which takes stretch into account, is used to describe the initial combustion phase. The difference between heat losses to the electrodes and the cylinder wall is considered. The burning velocity varies from the order of the laminar velocity to the fully developed burning velocity. The evolution is determined as well by the life time as by the size of the kernel. The stretch (caused by turbulence and by the growth of the kernel), the nonadiabatic character of the flame, and instabilities have influence on the laminar burning velocity. Validation of this model is done using measurements of the expansion in a propane-air mixture executed by Pischinger [2] at M.I.T. The agreement seems very good.