Готові списки джерел за темами / Grit accumulation

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Добірка наукової літератури з теми "Grit accumulation"

Автор: Grafiati

Опубліковано: 4 червня 2021

Оновлено: 1 лютого 2022

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Статті в журналах з теми "Grit accumulation"

Plana, Q., J. Carpentier, F. Tardif, A. Pauléat, A. Gadbois, P. Lessard, and P. A. Vanrolleghem. "Grit particle characterization: influence of sample pretreatment and sieving method." Water Science and Technology 78, no. 6 (September 26, 2018): 1400–1406. http://dx.doi.org/10.2166/wst.2018.412.

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Abstract Grit causes problems in water resource recovery facilities (WRRFs): clogging pipes, damaging pumps, and reducing the active volume of aeration tanks and anaerobic digesters by grit accumulation. Grit chambers are built to remove these particles. However, no standardized methodology exists to characterize grit particles for grit chamber design and operation despite the large observed variability in grit composition. Therefore, this paper proposes a combination and adaptation of existing methods to sample and characterize grit particles in view of proper grit chamber design and its modelling to ultimately optimize the efficiency of this important WRRF unit process. Characteristics evaluated included particle size distribution from sieving after different sample pretreatments, organic/inorganic fractions, and density.

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Bervoets, Lieven, Tinne Snoeijs, Tom Dauwe, Marcel Eens, and Ronny Blust. "Calcium availability influences lead accumulation in a passerine bird." Animal Biology 56, no. 3 (2006): 289–98. http://dx.doi.org/10.1163/157075606778441822.

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AbstractThe emission of heavy metals in the environment is often accompanied by emissions of acidifying pollutants. The acidification of terrestrial ecosystems results in the leaching of calcium and consequently a lowered concentration or availability of this essential nutrient in the environment. Calcium deficiency in the diet may lead to an increased absorption of toxic metals. In this study we investigated the effect of calcium availability on the accumulation of lead and essential metals (calcium, copper, iron and zinc) in important target tissues of zebra finches (Taeniopygia guttata). When exposed to 20 ppm lead via drinking water, zebra finches excluded from an additional calcium supply (i.e. oyster shell grit) accumulated significantly higher concentrations of lead in liver, kidney, muscle, brain and bone than zebra finches with access to oyster shell grit. Levels of calcium, copper, iron and zinc were not significantly affected by either the calcium availability or the increased absorption of lead. There were no significant sex related differences, suggesting that males and females have a similar demand, metabolism and/or distribution of calcium and other metals in the non-reproductive period. This study clearly illustrates the importance of calcium supply on the bioavailability of lead.

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Fouad, Moharram, and Ahmed El-Morsy. "Sludge accumulation pattern inside oxidation ditch case study." Water Science and Technology 69, no. 12 (April 3, 2014): 2468–75. http://dx.doi.org/10.2166/wst.2014.151.

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The sludge accumulation pattern of an oxidation ditch (OD) plant treating municipal wastewater was observed under dry and wet weather conditions, during 3 years of operation. The accumulation patterns along the ditches and their rates were revealed. In addition, the composition of the accumulation was investigated. Finally, the ratio of sand and volatile particles, mixed liquor suspended solids (MLSS), and mixed liquor volatile suspended solids, as well as the removal efficiency were also observed against the accumulated sludge. Further, a laboratory-scale channel was used to investigate the settleability of grit after mixing with variable values of MLSS. The observed results indicated that the economical design and operation of ODs using a velocity value between 0.3–0.35 m/s is not recommended, to avoid the settling of all solids. High values of MLSS and sludge age need high horizontal velocity (more than 0.35 m/s) and more power to avoid settling problems and system failure. The influence of flow velocity on the sludge settleability was studied, enabling better planning of future ditch design and operation.

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Li, Yong Peng, Hui Huang, and Xi Peng Xu. "Development Evaluation of Mechanical Properties of Brazed Diamond Wire." Solid State Phenomena 175 (June 2011): 294–99. http://dx.doi.org/10.4028/www.scientific.net/ssp.175.294.

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Fixed-abrasive wire saw, with its ability to cut hard brittle material, such as silicon ingots, crystals and quartz, has emerged as a leading technology for production in semiconductor and photovoltaic industry. There are some defects in conventional fixed-abrasive wire saw such as significant low holding abrasive ability, low machining efficiency, high running costs, etc. A new fixed-abrasive wire, namely brazed diamond wires have been developed to overcome these problems. In this paper, brazed diamond wire were carried out to braze two different size diamond grits onto two different thin steel wires by using a nickel-based powder as brazing alloy. The mechanical properties of brazed diamond wire were evaluated by tensile and breaking twist experiment. The experimental results showed that the heating in the brazing process has litter influence on the wire mechanical properties. The addition of brazed alloy and diamond grits sharply decreased the wire mechanical properties significantly, both in the tensile strength and breaking twist angle. Bigger diamond grit would make the accumulation of brazed alloy which leaded to the deterioration of diameter consistency of wires.

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Du, Fuyi, Qingjie Xie, Longxiang Fang, and Hang Su. "Comparative study on nutrient removal of agricultural non-point source pollution for three filter media filling schemes in eco-soil reactors." Journal of Water and Health 14, no. 4 (February 8, 2016): 600–608. http://dx.doi.org/10.2166/wh.2016.189.

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Nutrients (nitrogen and phosphorus) from agricultural non-point source (NPS) pollution have been increasingly recognized as a major contributor to the deterioration of water quality in recent years. The purpose of this article is to investigate the discrepancies in interception of nutrients in agricultural NPS pollution for eco-soil reactors using different filling schemes. Parallel eco-soil reactors of laboratory scale were created and filled with filter media, such as grit, zeolite, limestone, and gravel. Three filling schemes were adopted: increasing-sized filling (I-filling), decreasing-sized filling (D-filling), and blend-sized filling (B-filling). The systems were intermittent operations via simulated rainstorm runoff. The nutrient removal efficiency, biomass accumulation and vertical dissolved oxygen (DO) distribution were defined to assess the performance of eco-soil. The results showed that B-filling reactor presented an ideal DO for partial nitrification–denitrification across the eco-soil, and B-filling was the most stable in the change of bio-film accumulation trends with depth in the three fillings. Simultaneous and highest removals of NH4+-N (57.74–70.52%), total nitrogen (43.69–54.50%), and total phosphorus (42.50–55.00%) were obtained in the B-filling, demonstrating the efficiency of the blend filling schemes of eco-soil for oxygen transfer and biomass accumulation to cope with agricultural NPS pollution.

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O'Mara, Peter T., Marilyn Merryweather, Mark Stockwell, and Mike M. Bowler. "The Trent Gas Field, Block 43/24a, UK North Sea." Geological Society, London, Memoirs 20, no. 1 (2003): 835–49. http://dx.doi.org/10.1144/gsl.mem.2003.020.01.70.

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AbstractThe Trent gas field lies within the UKCS Southern Gas Basin (Block 43/24a) located 120 km off the Yorkshire coast in average water depths of 160 ft. The accumulation is contained within a NW-SE trending Base Permian closure, which straddles blocks 43/24, 43/23 and 43/25. The Carboniferous subcrop beneath the Base Permian unconformity varies in age from Westphalian A in the east to Namurian in the west. Although the Base Permian closure covers an area of 75 km2 the producible reserves are only located in the central core area of 43/24a. The main reservoir horizon is the Trent Sandstone of Marsdenian age, equivalent to the Chatsworth Grit Sandstone, UK onshore. Additional reservoir zones are within the lowermost Westphalian A. The field has been developed through the application of fracture stimulation of deviated wells.

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Miranda, Rafael de Souza, Fabricio Bonfim Suderio, Elton Camelo Marques, and Eneas Gomes-Filho. "ACCUMULATION AND PARTITION OF Fe, Zn, Cu, Mn AND Na IN MACRO AND MICRONUTRIENT-DEFICIENT COWPEA PLANTS." JOURNAL OF ADVANCES IN AGRICULTURE 7, no. 2 (July 22, 2017): 1036–43. http://dx.doi.org/10.24297/jaa.v7i2.6237.

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Cowpea (Vigna unguiculata) is an important crop for people living in the semi-arid tropics where it is used as food, animal feed and forage. Researches related to nutritional status of plants are important, principally in crops commonly grown in nutrient-poor soils. This study aimed to analyze the growth and accumulation/distribution of some micronutrients in cowpea plants submitted to macro and micronutrient deficiency. Cowpea seeds were germinated in grit and after five days, ten uniform seedlings were transferred to complete nutrient solution for an acclimatization period. After three days, the plants were grown in nutrient solution containing all macro and micronutrients or in nutrient solution without N, Ca, K, Mg, P, S, Fe, B or aeration. In all case, omission of mineral nutrients and the aeration caused reductions in the dry mass of cowpea plants, except for B; however, the absence of Ca was the most limiting for plant growth. Interestingly, the root Fe content significantly increased in Mg-, P- and S-deficient plants. Yet, Fe-deficient plants displayed a significant increase in Cu and Mn content, regardless of plant organ. Our data clearly demonstrate that the Ca is the most important nutrient for V. unguiculata growth, followed by N and Fe. The accumulation and partition of Fe, Zn, Cu and Mn in cowpea vary differentially in root, stem and leaf as affected by nutritional deficiency.

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Zhang, Jing Jun, and Cheng Zhi Liu. "Wuerxun Depression Fan Delta Depositional System Research of Nantun Formation in Wubei Sub-Depression." Applied Mechanics and Materials 328 (June 2013): 308–13. http://dx.doi.org/10.4028/www.scientific.net/amm.328.308.

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Fan delta facies deposition are developed in the steep slope of faulted lake basin and have features ,such as the rapid accumulation, from near provenance, clastic coarse granularity and poor sorting. By means of core, logging, well logging and seismic data, based on the sedimentary characteristics of Nantun formation of Wuerxun depression, the conclusions are as followings: Faulted basin steep slope belts are developed fan delta depositional system with volcano facies in Wubei sub-depression of Wuerxun depression;The fan delta system are divided into plain,front and front fan delta etc,three subfacies, seven microfacies; In distributary channel microfacies, sand conglomerate, gravel sandstone, middle-grit are main lithology, low maturity, poor sorting to medium, vertical sequence, visible bottom gravel and erosion surface, large scale cross-bedding are developed, partial visible horizontal bedding; channel mouth bar microfacies relatively rudimentary, lithology with sorting relatively good powdermiddle sandstone, development of small cross-bedding, horizontal bedding.

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Azimi, Seyed Mostafa, Nasroallah Moradi Kor, Madeh Ahmadi, Morad Shaaban, Zahra Rahmati Motlagh, and Morteza Shamsizadeh. "Investigation of growth analysis in chickpea (Cicer arietinum L.) cultivars under drought stress." International Journal of Life Sciences 9, no. 5 (June 14, 2015): 91–94. http://dx.doi.org/10.3126/ijls.v9i5.12705.

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A field experiment performed in order to evaluate the effects of drought stress on growth indices of chickpea cultivars. This experiment was performed in factorial using randomized complete block design with three replications. Treatments were drought stress treatment in in three levels consisting of no drought stress (control), moderate drought stress (irrigation at planting and early flowering) and severe drought stress (no irrigation) and cultivar treatment (three cultivars Azad, Grit and ILC482). Results showed that LAI, CGR, RGR and NAR reduced with increased in drought stress level. Also, LAR decreased after short time increasing. Non stress condition caused to improve growth stages and increase accumulation of dry matter and yield in chickpea. Maximum LAI, LAR and CGR obtaind at 56 days after sowing under non irrigation condition, but under complete irrigation they were observed at 77 days after sowing. RGR and NAR reduced with increasing the age of the plant. Thus we concluded that drought stress decreased growth of chickpea and final yield of it.DOI: http://dx.doi.org/10.3126/ijls.v9i5.12705

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Lebrun, Manhattan, Elena De Zio, Florie Miard, Gabriella S. Scippa, Giovanni Renzone, Andrea Scaloni, Sylvain Bourgerie, Domenico Morabito, and Dalila Trupiano. "Amending an As/Pb contaminated soil with biochar, compost and iron grit: effect on Salix viminalis growth, root proteome profiles and metal(loid) accumulation indexes." Chemosphere 244 (April 2020): 125397. http://dx.doi.org/10.1016/j.chemosphere.2019.125397.

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Більше джерел

Дисертації з теми "Grit accumulation"

Bažant, Zdeněk. "Rodinný dům - aktivní uzel ve Smart Grid." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2014. http://www.nusl.cz/ntk/nusl-220943.

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This thesis deals with issues of smart houses and smart buildings. In the first part there is a research of possible systems installed in smart house. Each system is described from the perspective of its function and importance .The second part is focused on energy demands and where there is described European standard EN 15232 (Energy demand of building – influence of control automation and house management). In the practical part there was created scheme with devices which can be equipped smart houses with and their separation according to their relation to electricity. Each device is characterized by its electrical and nonelectrical parameters typical for family houses. Next part is about the proposal of prediction model of electricity consumption and generation. There are also stated quantities needed for prediction model and then method for prediction model realization.

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Chlebný, Radek. "Autonomní dům aneb život grid-off." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2013. http://www.nusl.cz/ntk/nusl-220159.

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This thesis deals with energy self-sufficiency focusing on the independence of the electric grid. Basic line emanating project form a concrete proposal for autonomous energy supply system. Emphasis is placed primarily on photovoltaic systems, electric energy accumulation and selection of individual components of such a system. Another important part of the thesis is also an economic evaluation of design variations. The thesis also deals with a market research, and thereof derived benefit assessment of each technology. The accompanying chapters are then devoted to the history of autonomous life style or classification of buildings according to their energy performance.

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Moravčík, Martin. "Modelování a simulace hybridní mikro sítě v prostředí PSCAD." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2012. http://www.nusl.cz/ntk/nusl-219410.

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In the opening part of this master´s thesis there is given concept, description, usage and advantages of micro hybrid grids in comparison to micro grids and there are evolution steps towards hybrid grid. There is also a mention about economics of operation of these grids. In the second part of this thesis there are descriptions of devices that are suitable for usage in micro hybrid grids with emphasis on generators and accumulation possibilities. In the next part of this thesis there is given an approach and description for modeling of various components of hybrid grids in PSCAD environment. In the next part of this thesis there are given simulation results that were conducted on created model. Especially power balance in 24 hour operation of the grid with method for determining suitable size of accumulation and installed capacity of photovoltaics. And next there are showed responses from change of power from photovoltaics, next there is a transition to islanded mode and last there is showed the behavior of converter when the limits of accumulation are reached. In the final part of this thesis there are conclusions, fulfillment of goals of this thesis and possibilities of further study.

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Dolinský, Filip. "Ostrovní systémy." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2018. http://www.nusl.cz/ntk/nusl-378496.

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Master thesis deals with usage issues of autonomous, self-sufficient and decentralized systems. In the first part convectional and experimental sources for autonomous systems are disclosed. Second chapter deals with accumulation of electrical and thermal energy and possibilities of applications. 3rd part is focused on pilot project realized for autonomous and smart systems, which were built in last years. In the 4th chapter electrical and thermal energy consumption curves are made on daily and monthly basis for 4 type objects. In the fifth part issue of autonomy is explained, and for type buildings solutions are made with additional return on investment. The last chapter is focused on calculation of thermal accumulator and briefly discloses small district heating.

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Pauget, Benjamin. "Détermination des facteurs du sol modulant la biodisponibilité et l'accumulation des métaux pour l'escargot (cantareus aspersus)." Thesis, Besançon, 2012. http://www.theses.fr/2012BESA2022/document.

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[...] L’objectif decette thèse est l’étude des mécanismes modulant la biodisponibilité des métaux pour l’escargotCantareus aspersus (syn. Helix aspersa), invertébré vivant à l’interface sol‐plante‐air (maillonintermédiaire, saprophage, phytophage, de chaînes alimentaires). La biodisponibilité est principalementévaluée ici en mesurant l’accumulation (concentrations internes en métaux après 28 jours d’exposition) etles flux d’assimilation. L’influence de paramètres édaphiques sur la disponibilité et la biodisponibilité desmétaux des sols et la contribution des sources de contamination (sols/plantes) des escargots constituentles variables étudiées dans deux conditions d'exposition :[...] L’ensemble des résultats souligne la nécessité de prendre en compte les facteurs et lesmécanismes qui modulent la biodisponibilité des métaux pour modéliser au mieux leur accumulation etleur assimilation par les escargots. Aucune méthode chimique unique d’estimation de la biodisponibilitédes métaux n’ayant pu être déterminée, nous préconisons l’utilisation de mesures biologiques quireflètent mieux la réelle biodisponibilité
[...] The aim of this thesis is to study the mechanisms that modulate metal bioavailabilityfor the garden snail Cantareus aspersus (= Helix aspersa) a soil invertebrate living at the interfacesoil‐plant‐air (saprophagous and phytophagous intermediate link in the food chain).[...] These data underline the necessity to take into account the factors and mechanisms that modulate themetal bioavailability for snails to better model accumulation and assimilation of metal by snails. As nounique chemical method to assess metal bioavailability was determined, we recommend the use ofbiological measures that identify the real metal bioavailability rather than the use of chemical measures

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Bender, Cristel. "Diet and the Dietary Niches of the Malagasy Subfossil Lemurs: An Analysis of Dental Microwear, Dental Proportions, and Grit Accumulation." 2017. http://scholarworks.gsu.edu/anthro_theses/115.

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The purpose of this study is to identify the currently supported diet and dietary niches of the Malagasy subfossil and extant lemurs. The study was conducted partially in Tsinjoarivo and Antananarivo, Madagascar in the summer of 2013. Samples were analyzed and microwear determined that the dietary niches were aligned with current literature. Grit accumulation occurs more frequently in disturbed habitats and on lower canopy levels, which suggests that human manipulation of environment can impact the dental microwear of living primates.

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KRČKA, Pavel. "Fotovoltaické dobíjecí regulátory v ostrovních systémech." Master's thesis, 2013. http://www.nusl.cz/ntk/nusl-156255.

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This diploma thesis deals with photovoltaic rechargable regulators used in isolated, or off-grid photovoltaic systems. First, basic types of off-grid installations, including their functions and applications in practice are described. Then, possibilities of electric energy accumulation in photovoltaic systems are mentioned, considering actual, accesible technologies. Matters of electric energy accumulation in leaden accumulators are examined in detail. Main part of the diploma thesis is about electronic designs of photovoltaic, also called solar, rechargable regulators. These are the main connecting part between photovoltaic panels, accumulator, but also often connected charge, which is appliance. Individual electronic regulators concepts are described narrowly, then compared and evaluated in thesis´ conclusion.

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Частини книг з теми "Grit accumulation"

Runovska, Zoia. "Study of a Process of Task Accumulation and Distribution in a GRID-System." In Operations Research Proceedings, 493–97. Cham: Springer International Publishing, 2013. http://dx.doi.org/10.1007/978-3-319-00795-3_74.

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Dahl-Jensen, D., S. J. Johnsen, C. U. Hammer, H. B. Clausen, and J. Jouzel. "Past Accumulation rates derived from observed annual layers in the GRIP ice core from Summit, Central Greenland." In Ice in the Climate System, 517–32. Berlin, Heidelberg: Springer Berlin Heidelberg, 1993. http://dx.doi.org/10.1007/978-3-642-85016-5_29.

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Rottoli, Marco, Daniele Agazzi, Marcello Garavaglia, and Fabio Grisoni. "EMbaffle® Heat Transfer Technology Step-Up in CO2 Reduction." In Heat Transfer - Design, Experimentation and Applications [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.96253.

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EMbaffle® is a proprietary shell and tube heat exchanger technology, designed to improve performance by pressure drops control, with suppressed tube vibrations. Developed to minimize fouling accumulation in crude oil units, the technology has proved to be effective in Gas treatment and Petrochemical, supporting the increase in gas–gas and cooling water flow rate per-unit demand, and in Renewable CSP, where Molten Salt units get a primary role in thermal storage and power efficiency. Diamond shape and baffle-grids number are the instruments for the design engineer to exploit exchanger efficiency against pressure drops, aimed to the desired performance with the optimized power consumption. Further to introduce the base of the technology, this work will also address the design of higher compact units by combining the grids performance with the improved exchanger tube surface. Experimental data to support the grid life under critical working conditions and actual performances with fluids density and viscosity are reported.

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Chaves, H. A. F. "Characteristic Analysis As An Oil Exploration Tool." In Computers in Geology - 25 Years of Progress. Oxford University Press, 1994. http://dx.doi.org/10.1093/oso/9780195085938.003.0013.

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Characteristic analysis is well known in mineral resources appraisal and has proved useful for petroleum exploration. It also can be used to integrate geological data in sedimentary basin analysis and hydrocarbon assessment, considering geological relationships and uncertainties that result from lack of basic geological knowledge, A generalization of characteristic analysis, using fuzzy-set theory and fuzzy logic, may prove better for quantification of geologic analogues and also for description of reservoir and sedimentary facies. Characteristic analysis is a discrete multivariate procedure for combining and interpreting data; Botbol (1971) originally proposed its application to geology, geochemistry, and geophysics. It has been applied mainly in the search for poorly exposed or concealed mineral deposits by exploring joint occurrences or absences of mineralogical, lithological, and structural attributes (McCammon et al., 1981). It forms part of a systematic approach to resource appraisal and integration of generalized and specific geological knowledge (Chaves, 1988, 1989; Chaves and Lewis, 1989). The technique usually requires some form of discrete sampling to be applicable—generally a spatial discretization of maps into cells or regular grids (Melo, 1988). Characteristic analysis attempts to determine the joint occurrences of various attributes that are favorable for, related to, or indicative of the occurrence of the desired phenomenon or target. In geological applications, the target usually is an economic accumulation of energy or mineral resources. Applying characteristic analysis requires the following steps: 1) the studied area is sampled using a regular square or rectangular grid of cells; 2) in each cell the favorabilities of the variables are expressed in binary or ternary form; 3) a model is chosen that indicates the cells that include the target (Sinding-Larsen et al, 1979); and 4) a combined favorability map of the area is produced that points out possible new targets. The favorability of individual variables is expressed either in binary form— assigning a value of +1 to favorable and a value of 0 to unfavorable or unevaluated variables—or in ternary form if the two states represented by 0 are distinguishable—the value +1 again means favorable, the value —1 means unfavorable, and the value 0 means unevaluated.

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"Initially, mine workers would be rather reluctant to invest their wages in means of production (in agriculture and in transport) within the Mozambican rural economy. Up to 1980/81, government policies were not favourable to such investments. However, thereafter, miners were specifically encouraged to plough back their wages into production and commerce. Rural unemployment was widespread and, hence, the conditions for private accumulation were favourable on this count. Generally, miners would invest in transport and commerce, but some did invest in agriculture. Indeed, in the latter years, peasants with resources were allowed to operate on unutilised ex-settler farms. In other cases, the more permanent and better paid state farm workers could use their specific position to strengthen their own farm, often supplemented by hired labour. As mechanics or tractor drivers, etc. they had access to cer-tain resources such as seeds, fertiliser, fuel and consumer goods which they could buy either from the state farm or, not unfrequently, merely take from stocks on the state farms. Border areas were another such case of differentiated access to resources by means of barter trade cross the border. Due to the political criticality of such areas within a general condition of war, the government distribution policy would grant a certain priority to supplying these areas with commodities which would then provide a basis for further barter trade with the neighbouring country. Further, areas located more closely to the main food markets (either towns or plantations) would be subject to a much more dispersed and intensive barter and money trade, thereby raising the producer prices which would benefit those peasants who had sufficient resources to produce surpluses. More distant food producing areas were much more within the grip of the commercial traders who provided the link with the market. Hence, while some strata within the peasantry managed to create some room for themselves by producing for the parallel markets, the majority of rural producers (either as wage labourers or small-scale producers) confronted declining real incomes as a result of the inflation on the parallel markets to which they had to turn not only for industrial commodities but also to supplement their food needs. Hence, their problem was not one of having too much money at hand with too few commodities to buy; rather, they experi-enced an acute shortage of both money and goods. The poorer peasantry were the main suppliers of seasonal labour to the state sector. However, although rural unemployment was high, the supply of labour was by no means elastic. The reasons for this were the following. First, the pattern of labour demand of the state farms and plantations was in most cases highly seasonal and, hence, did not provide an all-round income for the worker. Second, money wages earned on the state farm did not guarantee any access to commodities, and often did so only at speculative prices. For both reasons, the real basis of security of the rural worker still remained his family farm, however fragile that may have been. The state sector may have become dominant in terms of area and in terms of production (regarding monetary output), but it certainly was not the dominant aspect in securing the livelihood of rural producers. In most cases, the pattern of peak demand for labour on the state farms coincided with the peak demand for labour in family agriculture. For example,." In The Agrarian Question in Socialist Transitions, 208. Routledge, 2013. http://dx.doi.org/10.4324/9780203043493-31.

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Тези доповідей конференцій з теми "Grit accumulation"

de Castro, Felipe Santos, Eduardo Tadashi Katsuno, Gustavo Roque da Silva Assi, and Joao Lucas Dozzi Dantas. "Structural Investigation of the Log Accumulation Effect in a Debris Containment Grid Through Towing Tank Experiments." In ASME 2018 37th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/omae2018-78097.

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The large-scale presence of debris is a recurrent issue in the Madeira River, located on Amazon rainforest, North of Brazil, and it is a major concern for the Santo Antonio hydropower plant, located at this region. In order to avoid the abundant amount of debris, floating structures called log booms are installed across the river to retain and deflect them. This paper aims to present the methods used to investigate the structural characteristics of a truncated scale model of a log boom line, through water proof strain-gauges and load cells in hydrodynamic experiments. For that, the model was towed along the model basin of the Institute for Technological Research and wooden scale logs were included to simulate the log jam phenomenon. The paper covers experiment methods, from model design to setting of data acquisition devices and system, characteristics of the experimental runs, and further data analysis. The influence of the scale debris on the structural elements are presented, which can leads to develop a correlation model to scale the fluid-structure interactions in the real prototype.

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Alves, Marcos G., Guilherme A. Melo, Carlos A. Canesin, and Moacyr A. G. de Brito. "Photovoltaic DG with accumulation, active and reactive power control for grid-connected and intentional islanding operations." In IECON 2017 - 43rd Annual Conference of the IEEE Industrial Electronics Society. IEEE, 2017. http://dx.doi.org/10.1109/iecon.2017.8216444.

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Alves, Marcos G., Moacyr A. G. de Brito, Guilherme A. Melo, and Carlos A. Canesin. "Photovoltaic DG with accumulation, active and reactive power control for grid-connected and intentional islanding operations." In 2017 Brazilian Power Electronics Conference (COBEP). IEEE, 2017. http://dx.doi.org/10.1109/cobep.2017.8257408.

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Katopodes, Nikolaos D., and Kuo-Cheng Kao. "Nested Grid Models for Ocean Processes." In ASME 2005 24th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2005. http://dx.doi.org/10.1115/omae2005-67212.

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This paper presents a novel two-way nested grid scheme that allows information to travel freely through the computational boundaries of the grid interface. The method tentatively assumes the pressure boundary conditions between subdomains, but uses a receding boundary approach to minimize the pressure errors. Initially, the domains overlap, but within a few time steps the overlap is eliminated by the receding boundaries, so repeated use of approximate boundary conditions is avoided. This prevents the accumulation of errors on the subdomain boundaries and, furthermore, decreases the transfer of errors to the rest of the domain by continuously discarding boundary data. To avoid continuous shrinking of the subdomains, the boundaries are reset to their original positions every few time steps. Successful applications of the method are presented for surface wave propagation, gravity currents and a combination of both surface and internal waves.

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Gu¨rtner, Arne, Ibrahim Konuk, Ove Tobias Gudmestad, and Pavel Liferov. "Innovative Ice Protection for Shallow Water Drilling: Part III — Finite Element Modelling of Ice Rubble Accumulation." In ASME 2008 27th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2008. http://dx.doi.org/10.1115/omae2008-57915.

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The concept of the Shoulder Ice Barrier (SIB) has previously been presented in a companion paper under the same title at OMAE 2006 (Gu¨rtner et al., 2006), whereas ice model tests of the SIB are presented in an accompanying paper at this year’s OMAE (Gu¨rtner and Gudmestad, 2008). The present paper investigates a computational model for simulating ice-SIB interactions. This involves the simulation of rubble accumulations and accordingly the exerted ice forces. The computational model is developed within the framework of finite elements. Characteristic fracture of ice is handled by introducing the Cohesive Zone Approach (CZA), wherein cohesive elements are placed in-between the finite element grid of the ice. Fracture may thereby occur along element boundaries with due regard to fracture properties such as traction and separation. Fracture and plastic deformation of the ice are hence co-existing, though competing, mechanisms, while accounting for the dynamics of the ice mass. We compare the computational results with the ones obtained during the model testing.

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Mohr, Eric, Biswaranjan Mohanty, and Kim A. Stelson. "Short-Term Energy Storage System for Hydraulic Hybrid Wind Turbine Transmission." In BATH/ASME 2020 Symposium on Fluid Power and Motion Control. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/fpmc2020-2777.

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Abstract A Hydrostatic Transmission (HST) offers a variable ratio transmission for wind turbines that has a higher power to weight ratio than traditional gearboxes, and requires less maintenance. In a conventional turbine, when the wind speed increases above the rated speed, the blade pitch is controlled to dissipate excess energy and regulate the turbine at rated power. An energy storage system allows the turbine to temporarily operate above rated power, and capture the traditionally dissipated energy in an accumulator. When the wind speed drops below the rated speed, the energy in the accumulator is released, increasing the delivered power This paper presents a high-fidelity mathematical model of the hydraulic hybrid wind turbine transmission. Simulation results for a series of step changes and for turbulent wind speed are investigated for a 60 kW turbine. Using a realistic turbulent wind data sample, energy production increased by 4% with a 52 liter accumulator with significantly smoother output power to the grid.

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Zheng, Tieyu, and Zhen-Zhong Du. "Use Direct Cyclic and Sub-Modeling Approach to Analyze Solder Joint Fatigue Reliability." In ASME 2007 International Mechanical Engineering Congress and Exposition. ASMEDC, 2007. http://dx.doi.org/10.1115/imece2007-42366.

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Temperature change under the operating condition of an electronic product often leads to stress reversals and the accumulation of inelastic energy at the solder joints inside the packaging, resulting in the initiation and propagation of cracks in the solder joints. It is desired to predict the critical location of ball grid array (BGA) undergoing low-cycle fatigue and the fatigue life of the critical solder joints numerically to assess the development risks and guide the product design. This paper presents an approach by combining the direct cyclic method implemented by Abaqus and the sub-modeling method to achieve both goals with better computing efficiency than the traditional global-local approach.

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Masinde, Abiud, Cleophas Simiyu, Innocent Murunga, George Muia, Aaron Waswa, and Justus Barongo. "A Preliminary Assessment of the Hydrocarbon Potential of Kerio Valley Basin: Gravity and Magnetic Interpretation." In SPE/AAPG Africa Energy and Technology Conference. SPE, 2016. http://dx.doi.org/10.2118/afrc-2546156-ms.

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ABSTRACT The aim of the study was to assess the hydrocarbon prospectivity of the Kerio Basin in the Kenya Rift. An Isostatically corrected anomaly map produced from a Bouguer anomaly grid was filtered using a Hanning low pass filter of order 2 to remove low wavelengths. Four profiles were extracted from the grid to give 1D interpretation along straight lines. Magnetic grid was corrected for IGRF, diurnal, filtered using a 1 Hz low pass 10km Hanning filter to reduce noise, later, reduced to equator to place all anomalies directly over underlying sources and make anomalies less complicated. Tilt derivative of the magnetic grid was used to estimate depth to basement. The residual analytic signal anomaly map derived from the magnetic grid was used to capture the response of existing near surface magnetic signatures even the reversely magnetized ones. Kerio basin is characterised by low gravity anomalies ranging between 35mGals to −100mGals related to variations in quantities of sediments deposited. Gravity profiles show that sediment thickness gradually increases to the south where we expect hydrocarbon accumulation. The magnetic anomaly map reveals low susceptibility rocks of between −20nT to −200nT to the south of the basin. Magnetic tilt depth indicates sediment thickness of 2.0-3.5Km above the basement. This corresponds to both gravity and magnetic interpretation of the same area. Integration of these data with seismic and other constraints may help gauge the hydrocarbon potential and reduce exploration uncertainty in the southern area of the Kerio Basin.

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Harper, R. A., I. F. Lane, C. M. Backhouse, C. N. McCollum, and A. C. Meek. "PLATELET DEPOSITION AND PSEUDO-INTIMAL HYPERPLASIA IN PROSTHETIC VASCULAR GRAFTS." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643088.

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Platelet and fibrin accumulation in arterial grafts may cause pseudo-intimal hyperplasia and graft occlusion. The relationship between the rate of post-operative platelet accumulation and subsequent pseudo-intimal hyperplasia has been studied in prosthetic grafts implanted in greyhounds.The femoral artery in 30 greyhounds was replaced by a 6cm length of 6mm PTFE. Autologous 111In-platelet deposition over the graft was measured by probe and ratemeter for 7 days and radioactivity compared to the contralateral thigh. The daily increase in this ratio graft over reference was calculated as the Thrombogenicity Index (TI). Grafts were removed at 8 weeks and sectioned at 5, 30 and 55mm for measurement of pseudo-intimal thickening by grid microscopy.The animals subsequently developing occlusion or pseudo-intimal harrowing of greater than 50% of the lumen had a markedly greater TI of 0.22±0.027 compared to 0.03±0.019 in the 23 grafts maintaining wide patency (p<0.05). TI was highest in the 4 grafts which occluded at 0.3110.09 compared to 0.04±0.02 in the 26 that remained patent (p<0.01). There was a highly significant correlation (r=0.69) between post-operative TI and subsequent pseudo-intimal hyperplasia (p<0.001).Platelet deposition in the early post-operative period appears to promote the development of progressive pseudo-intimal thickening and ultimate occlusion

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Suo, Wei, MengYang Sun, Peng Wang, and Qi Wu. "Proposal-free One-stage Referring Expression via Grid-Word Cross-Attention." In Thirtieth International Joint Conference on Artificial Intelligence {IJCAI-21}. California: International Joint Conferences on Artificial Intelligence Organization, 2021. http://dx.doi.org/10.24963/ijcai.2021/143.

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Referring Expression Comprehension (REC) has become one of the most important tasks in visual reasoning, since it is an essential step for many vision-and-language tasks such as visual question answering. However, it has not been widely used in many downstream tasks because it suffers 1) two-stage methods exist heavy computation cost and inevitable error accumulation, and 2) one-stage methods have to depend on lots of hyper-parameters (such as anchors) to generate bounding box. In this paper, we present a proposal-free one-stage (PFOS) model that is able to regress the region-of-interest from the image, based on a textual query, in an end-to-end manner. Instead of using the dominant anchor proposal fashion, we directly take the dense-grid of image as input for a cross-attention transformer that learns grid-word correspondences. The final bounding box is predicted directly from the image without the time-consuming anchor selection process that previous methods suffer. Our model achieves the state-of-the-art performance on four referring expression datasets with higher efficiency, comparing to previous best one-stage and two-stage methods.

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