Bibliografias temáticas / Root modelling

Índice

Artigos de revistas
Teses / dissertações
Livros
Capítulos de livros
Trabalhos de conferências
Relatórios de organizações

Literatura científica selecionada sobre o tema "Root modelling"

Autor: Grafiati

Publicado: 22 de fevereiro de 2025

Crie uma referência precisa em APA, MLA, Chicago, Harvard, e outros estilos

Selecione um tipo de fonte:

Consulte a lista de atuais artigos, livros, teses, anais de congressos e outras fontes científicas relevantes para o tema "Root modelling".

Ao lado de cada fonte na lista de referências, há um botão "Adicionar à bibliografia". Clique e geraremos automaticamente a citação bibliográfica do trabalho escolhido no estilo de citação de que você precisa: APA, MLA, Harvard, Chicago, Vancouver, etc.

Você também pode baixar o texto completo da publicação científica em formato .pdf e ler o resumo do trabalho online se estiver presente nos metadados.

Artigos de revistas sobre o assunto "Root modelling"

Phan, Trung Nghia, Anthony Kwan Leung, Thanh Son Nguyen, Viroon Kamchoom e Suched Likitlersuang. "Modelling root decomposition effects on root reinforcement and slope stability". Computers and Geotechnics 179 (março de 2025): 107024. https://doi.org/10.1016/j.compgeo.2024.107024.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Chopart, Jean-Louis, Silvia Rosa Rodrigues, Mateus Carvalho de Azevedo e Cristiane de Conti Medina. "Estimating sugarcane root length density through root mapping and orientation modelling". Plant and Soil 313, n.º 1-2 (28 de junho de 2008): 101–12. http://dx.doi.org/10.1007/s11104-008-9683-4.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Fata, Yulia Amirul, Hendrayanto Hendrayanto, Erizal Erizal, Suria Darma Tarigan e Takeshi Katsumi. "Modelling of mechanical roots on slope stability". Journal of Degraded and Mining Lands Management 10, n.º 4 (1 de julho de 2023): 4779. http://dx.doi.org/10.15243/jdmlm.2023.104.4779.

Texto completo da fonte

Resumo:

Root system mechanical reinforcement through root-soil cohesion on slope stability is important. However, the root cohesion of Tectona grandis, Maesopsis eminii, and shrubs (Chromolaena odorata) on slope stability is rarely studied and modelled. This study aimed to model the mechanical effect of vegetation through root cohesion, namely teak (Tectona grandis), Maesopsis eminii, and shrubs (Chromolaena odorata). The study was conducted in a simultaneous landslide on January 1, 2020, that dominantly occurred on vegetated slopes of Sukajaya District, Bogor Regency, West Java. The Wu model's root cohesion (CR) was modelled on slope stability using a modified Bishop model. The modelling used the data from field and laboratory-measured. The study found that the presence of a root system increases slope stability's factor of safety (FOS). The root system of young Maesopsiss eminii produces the largest effect of FOS compared to the root system of shrubs, teak, and old Maesopsis eminii. The slope stability of vegetated slopes is a function of the CR and the effective root zone depth. The highest total CR of vegetation was teak with 0.398 kPa, followed by shrubs, young Maesopsis eminii, and old Maesopsis eminii with 0.202 kPa, 0.191 kPa, and 0.087 kPa, respectively. The effective root zone of teak, young Maesopsis eminii, and shrub were 500, 230, 140, and 66 cm, respectively.

Estilos ABNT, Harvard, Vancouver, APA, etc.

Sposaro, M. M., P. M. Berry, M. Sterling, A. J. Hall e C. A. Chimenti. "Modelling root and stem lodging in sunflower". Field Crops Research 119, n.º 1 (outubro de 2010): 125–34. http://dx.doi.org/10.1016/j.fcr.2010.06.021.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Tobin, B., J. Čermák, D. Chiatante, F. Danjon, A. Di Iorio, L. Dupuy, A. Eshel et al. "Towards developmental modelling of tree root systems". Plant Biosystems - An International Journal Dealing with all Aspects of Plant Biology 141, n.º 3 (novembro de 2007): 481–501. http://dx.doi.org/10.1080/11263500701626283.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Sonnenberg, R., M. F. Bransby, P. D. Hallett, A. G. Bengough, S. B. Mickovski e M. C. R. Davies. "Centrifuge modelling of soil slopes reinforced with vegetation". Canadian Geotechnical Journal 47, n.º 12 (dezembro de 2010): 1415–30. http://dx.doi.org/10.1139/t10-037.

Texto completo da fonte

Resumo:

This paper reports a series of geotechnical centrifuge model tests conducted to investigate the mechanical reinforcement of slopes by vegetation. Some of the model slopes contained young willow trees, which were grown in controlled conditions to provide different root distributions and mechanical properties. Slopes were brought to failure in the centrifuge by increasing water pressures. The failure mechanisms were investigated photographically and using post-test excavation. By measuring the soil properties and pore pressures in each test when failure occurred, slope stability calculations could be performed for each slope failure. These back-calculations of stability suggest that only a small amount of reinforcement was provided by the root system even when it was grown for 290 days before testing. In contrast, the use of the measured root properties and a commonly used root reinforcement model suggests that significant reinforcement should have been provided by the roots. This disparity is probably due to either inappropriate assumptions made in the root reinforcement model or soil alteration produced by root growth. Such disparities may exist in the application of root reinforcement models to full-scale slopes and therefore require additional study. The modelling technique outlined in this paper is suitable for further investigation of root mechanical interactions with slopes.

Estilos ABNT, Harvard, Vancouver, APA, etc.

Sonnenberg, R., M. F. Bransby, A. G. Bengough, P. D. Hallett e M. C. R. Davies. "Centrifuge modelling of soil slopes containing model plant roots". Canadian Geotechnical Journal 49, n.º 1 (janeiro de 2012): 1–17. http://dx.doi.org/10.1139/t11-081.

Texto completo da fonte

Resumo:

A series of centrifuge model tests were conducted to investigate the contribution of root reinforcement to slope stability. A compacted sandy clay slope, inclined at 45°, was reinforced with model roots. The model roots were varied in material, architecture, and numbers. They had stiffness values corresponding to upper and lower values found for plant roots. The architecture included taproots and branched roots. Slope collapse was triggered by raising the water table while soil displacements, pore-water pressures, and root strains were measured. The mode of failure was changed by the presence of roots from a progressive block failure to translational failure. The tests revealed how axial strains and bending strains were mobilized in the roots and how the roots influenced the slope failure mechanism. Different limit equilibrium slope stability calculations were performed at slope failure conditions to quantify the amount of reinforcement provided by different root types. These measured root reinforcement contributions were compared with those predicted according to common root reinforcement models. A reinforcement calculation method allowing for root pull-out was found to give the best agreement.

Estilos ABNT, Harvard, Vancouver, APA, etc.

Soethe, N., J. Lehmann e C. Engels. "Root tapering between branching points should be included in fractal root system analysis". Ecological Modelling 207, n.º 2-4 (outubro de 2007): 363–66. http://dx.doi.org/10.1016/j.ecolmodel.2007.05.007.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Dyson, Ashley P., Ali Tolooiyan e D. V. Griffiths. "Numerical Modelling Techniques for Stability Analysis of Slopes Reinforced with Shallow Roots". Geotechnics 3, n.º 2 (30 de abril de 2023): 278–300. http://dx.doi.org/10.3390/geotechnics3020016.

Texto completo da fonte

Resumo:

It is well recognised that plant vegetation and roots are capable of improving the shear strength of hillslopes by reinforcing soil shear resistance. Several key factors influencing the level of slope reinforcement include root geometry, orientation and strength. To assess the mechanical performance of vegetated slopes using numerical methods, root structures can be represented by beam and pile elements to mirror root behaviour. In contrast, root reinforcement can be modelled indirectly through a root cohesion factor, supplying additional strength to the soil surrounding the root zone. In this paper, correlations between these two numerical methods are presented, highlighting the applicability of each technique based on various root characteristics. Three types of root geometries are presented, consisting of a primary tap root, a secondary cohesion zone surrounding the main root and a root branching process. The results of the finite element analysis demonstrate the variation in the slope factor of safety for both methods, with a set of correlations between the two modelling approaches. A series of stability charts are presented for each method, quantifying the effects of root characteristics on slope reinforcement.

Estilos ABNT, Harvard, Vancouver, APA, etc.

Astore, Miro A., Po-Chia Chen, Shafagh Waters e Serdar Kuyucak. "Computer modelling the root cause of cystic fibrosis". Biophysical Journal 121, n.º 3 (fevereiro de 2022): 506a. http://dx.doi.org/10.1016/j.bpj.2021.11.268.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Mais fontes

Teses / dissertações sobre o assunto "Root modelling"

Moore, Simon Patrick Merewether. "Spatiotemporal modelling of hormonal crosstalk in the Arabidopsis root". Thesis, Durham University, 2018. http://etheses.dur.ac.uk/12624/.

Texto completo da fonte

Resumo:

Plant development, growth and response to varying environmental conditions, involves a complex network of overlapping interactions between plant signalling hormones and gene expression, known as ‘CROSSTALK’, which controls cell proliferation, elongation and differentiation. Hormone response, concentrations and gene expression levels vary through the root tip and display patterning, which ultimately drives development; however, little is known about how this is established. Models have been constructed to explain patterning, including a ‘physical’ auxin flux model in a simple rectangular 2-D multicellular Arabidopsis root which excludes crosstalk (Grieneisen et al., 2007), and a single cell ‘biological crosstalk’ model of multiple hormone and protein interactions in WT and mutants (Liu et al., 2010; Liu et al., 2013). The project goal was to combine these approaches by embedding the single cell biological crosstalk relationships into a 2-D multicellular root structure to reproduce experimentally observed hormone and gene expression patterning. An initial model was constructed and parameter values calibrated to meet fit criteria and produce a WT parameter set. The model proved robust to parameter variation, indicating that results did not rely on unique parameter value selections. Model results were compared to experimental data to test predictive capability and matched experimentally observed patterning and concentration trends for most species and mutants. A more realistic digital root map was then developed with additional auxin carriers to allow improved comparison between model and experimental images at a cell-scale level. The roles of auxin influx and efflux carriers in regulating auxin patterning were investigated by developing a ‘Recovery Principle’, where pattern perturbations due to changes in one carrier set could be recovered by adjustments to the other carrier set. Finally, using additional experimental data from the literature, the crosstalk network was revised to produce more representative cytokinin patterning. The model provides an explanation of crosstalk control of gene expression and patterning, and forms a foundation for future expansion of hormonal crosstalk and gene expression modelling in the Arabidopsis root. In summary, this project has developed predictive models to further explore hormone and gene expression levels and spatiotemporal pattern formation in the Arabidopsis thaliana root tip.

Estilos ABNT, Harvard, Vancouver, APA, etc.

Livingstone, D. "Modelling cell proliferation in a structured tissue". Thesis, University of Reading, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379764.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Thor, Magnus. "Heterobasidion root rot in Norway spruce : modelling incidence, control efficacy and economic consequences in Swedish forestry /". Uppsala : Department of Forest Mycology and Pathology, Swedish University of Agricultural Sciences, 2005. http://epsilon.slu.se/200505.pdf.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Mao, Zhun. "Temporal and spatial modelling of root reinforcement in natural montane and subalpine forests". Thesis, Montpellier 2, 2011. http://www.theses.fr/2011MON20118.

Texto completo da fonte

Resumo:

Il est généralement admis que la végétation peut stabiliser les pentes naturelles et artificielles contre les glissements de terrain superficiel. Par rapport au rôle mécanique, les racines renforcent le sol d'une pente en fournissant une cohésion additionnelle (cr). La quantification des cr est une étape essentielle pour évaluer la stabilité des pentes, quantifiée par le facteur de sécurité (FoS, défini par le ratio entre les forces de la résistance et les forces motrices sur une pente). La plupart des modèles prédictifs de cr existants ne prennent pas en compte la dynamique racinaire à l'échelle spatiale et temporelle qui peut conduire à une hétérogénéité de renforcement des racines. Ainsi, cette thèse vise à caractériser, quantifier et modéliser la répartition spatiale et temporelle de la dynamique racinaire ainsi que son impact sur la cr estimée. La distribution, croissance et mortalité racinaire ont été échantillonnées à l'aide de monolithes et de rhizotrons à deux altitudes dans des forêts mixtes et naturellement régénérées dans les Alpes françaises, composées d'îlots et de trouées. Avec les méthodes de modélisation statistique, une série de facteurs abiotiques et biotiques affectant la dynamique racinaire ont été étudiés. Pour quantifier les cr, une méta-analyse a été effectuée et les divers algorithmes de modélisation ont été employés et leurs résultats comparés. Cette étude a montré que: (i) dans un écosystème à espèces mixtes, la densité racinaire influence davantage les cr que les propriétés de la qualité racinaire; (ii) tous les facteurs abiotiques (altitude, paysage écologique, profondeur du sol et mois) peuvent faire varier la densité racinaire selon des conditions différentes du sol ; (iii) lors de l'observation de 1,5 ans à l'aide de rhizotrons, le cr augmente continuellement, rapidement dans la saison active et lentement pendant la saison dormante, mais cette augmentation est dépendante de la profondeur du sol, de l'altitude et du patch écologique ; (iv) malgré le fait que les racines les plus fines (]0, 1] mm en diamètre) soient les plus actives dans le cycle de nutritions et de carbone (selon des publications précédentes), elles contribuent peu au renforcement mécanique de terrain. Cette étude a permis d'élargir et d'approfondir nos connaissances sur le rôle des racines dans l'éco-ingénierie
It is largely recognized that vegetation can stabilize artificial and natural slopes against shallow landslides. Mechanically, plant roots reinforce soil on a slope by providing an additional cohesion (cr). Quantification of cr is a key step to estimate the stability of a given slope, usually quantified by the Factor of Safety (FoS, deﬁned as the ratio between resisting forces and the driving forces on a slope). Most existing cr predictive models do not take into consideration spatial and temporal root dynamics which result in heterogeneous root reinforcement along a vegetated slope. Therefore, this thesis aims to characterize, quantify and model the spatial and temporal patterns in root dynamics and their impact on the estimation of cr. Root distribution, growth and mortality were measured using monoliths and rhizotrons installed at two altitudes in naturally regenerated mixed forests in the French Alps. These forests are composed of trees growing in groups (tree islands) with large gaps between the islands. Using statistical modeling approaches, abiotic and biotic factors affecting root dynamics were investigated. For quantifying cr, a meta-analysis was performed and different modeling algorithms were employed and results compared. Based on these studies, the following conclusions were made: (i) in a mixed, mature forest ecosystem root density influenced cr more than root mechanical properties; (ii) all abiotic factors (altitude, type of vegetation patch, soil depth and month) significantly affected root quantity to different degrees, depending on soil conditions; (iii) during the 1.5 years' observations in rhizotron, cr increased rapidly during the growing season and more slowly in the dormant season but the increment increase was largely dependent on soil depth, altitude and vegetation patch. (iv) The finest roots (]0, 1] mm in diameter), which are considered the most important for nutrient and carbon cycling, contributed little to mechanical reinforcement of the soil. Results are discussed with regard to ecological engineering strategies for unstable slopes

Estilos ABNT, Harvard, Vancouver, APA, etc.

Mellor, Nathan L. "Multiscale modelling of plant hormone signalling : auxin regulated lateral root emergence". Thesis, University of Nottingham, 2013. http://eprints.nottingham.ac.uk/30420/.

Texto completo da fonte

Resumo:

The formation of lateral roots is an important post-embryonic developmental process that allows plants to adapt to their environment via exploitation of soil mineral resources. New lateral roots initiate as lateral root primordia (LRP) in the pericycle cell layer adjacent to the central vascular tissue in the primary root, and must pass through the outer cell layers of endodermis, cortex and epidermis to emerge as mature roots. A key regulator of emergence is the plant hormone auxin and it has been shown previously that in Arabidopsis the auxin induced expression of the auxin influx carrier LAX3 in specific cortical cells over LRP is required for emergence to occur, as this leads to the expression of cell wall remodelling enzymes such as polygalacturonase (PG). By developing mathematical models of auxin transport and LAX3 expression the work in the thesis aims to test the existing conceptual models for lateral root emergence, and provide testable hypotheses for the existence of additional gene regulatory components. An initial single cell model demonstrates that hysteresis and bistability may explain the experimentally observed 'all-or-nothing' LAX3 spatial expression pattern in cortical cells containing a gradient of auxin concentrations. By fitting model parameters against experimental data, the model is then used to show that some auxin homeostasis mechanism is present, with both endogenous and exogenous sources of homeostasis investigated. The single cell model also investigates the validity of several alternative gene regulatory networks for LAX3, and its apparent repression by a key mediator of the auxin response, ARF19. Finally, the model is extended to a multicellular context, in which the auxin distribution from a simulated LRP source cell is used as a basis for the expression of LAX3, leading to the expression of PG in specific cells between which the LRP must pass.

Estilos ABNT, Harvard, Vancouver, APA, etc.

Tsegaye, Tezera. "Modelling the effect of variable soil impedance on pea root growth". Thesis, University of Aberdeen, 1992. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU045142.

Texto completo da fonte

Resumo:

Experiments were conducted: (i) to investigate varietal differences in pea (Pisum sativum L.) root response to mechanical impedance, (ii) to study the effect of mechanical impedance on root growth and morphology and (iii) to predict root growth in soils whose mechanical impedance varied temporally and spatially by adapting the Diggle (1988), ROOTMAP, model. Pea varieties whose root growth rates did not differ under unimpeded conditions had their root growth rates reduced by significantly different proportions in response to mechanical impedance. Highly significant correlations between first order lateral elongation rate and diameter were observed for pea roots grown in moist vermiculite. There was also evidence that regular stimulation of the root tip is required to trigger lateral emergence. An experimental procedure for obtaining ROOTMAP input parameters was devised and the growth and distribution of pea roots grown for 29 days in soil whose mechanical impedance varied with time and depth as a result of soil drying out, was successfully predicted. These findings highlight the potential that exists for selecting and breeding varieties based on root characters that confer insensitivity of response to mechanical impedance and for using ROOTMAP to investigate the growth response of different crop varieties in realistic soil scenarios.

Estilos ABNT, Harvard, Vancouver, APA, etc.

Brassett, P. R. "Computer simulation of the take-all disease of winter wheat with particular reference to methodology". Thesis, University of Cambridge, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233678.

Texto completo da fonte

Resumo:

The theory and the practical application of the simulation of root infection of winter wheat by the take-all fungus, Gaeumannomyces graminis var. tritici, are critically evaluated with respect to field epidemics and to infection of seedlings within controlled environments. Several simple models for disease progress in field epidemics are evaluated with respect to field data, including a generalized logistic equation and systems of simple non-linear differential equations, with and without algebraic solutions. An investigation is made of disease heterogeneity in the field and transect data derived from sampling 11,000 plants are analysed for the presence of significant pattern. The effect of the observed spatial heterogeneity on the precision of field data is also empirically investigated. The use of a controlled-environment experiment to model the effect of volunteer infestation on inoculum survival in the field is demonstrated, and a simple model is used to quantitatively estimate the effect of volunteer infestation on inoculum multiplication. Data for a seedling disease epidemic are simulated by three mathematically and computationally diverse simulators derived from a single underlying theoretical model. The first is a complex simulator written in FORTRAN and run on a mainframe computer which resolves the infection process into a number of detailed submodels. The second simulator is written in BBCBASIC and 6502 machine code and makes use of a discrete root map to hold information on host growth and infection. In the third simulator the model is expressed as a series of rate equations and is run on a simulation package on the BBC microcomputer. The simulation techniques used are discussed and evaluated with respect to model development and the descriptive accuracy of the simulators. In conclusion a strategy is proposed for the development of a comprehensive model for field epidemics of take-all by means of controlled-environment experimentation.

Estilos ABNT, Harvard, Vancouver, APA, etc.

Cropp, Roger Allan, e R. Cropp@griffith edu au. "A Biogeochemical Modelling Analysis of the Potential For Marine Ecosystems to Regulate Climate By the Production of Dimethylsulphide". Griffith University. Australian School of Environmental Studies, 2003. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20030703.101310.

Texto completo da fonte

Resumo:

The potential for life to control its environment was first suggested by Lovelock (1972). Charlson et al (1987) proposed a role for marine planktonic ecosystems in global climate regulation via the production and ventilation to the atmosphere of dimethylsulphide (DMS), a by-product of phytoplankton metabolism. Once in the atmosphere DMS contributes to the formation of cloud condensation nuclei, and increases the amount and brightness of cloud. This affects the albedo of the planet, reflecting more incident sunlight back into space, and cooling the earth. In common with many other 'hypotheses' regarding complex adaptive systems, the hypothesis proposed by Charlson et al (1987) is not experimentally testable. The production and ventilation to the atmosphere of DMS is the result of complex interactions between biological, chemical and physical processes. Consequently, increasing use is being made of mathematical models that simulate these processes to advance understanding of it (Archer et al. 2002). This study examines one of the fundamental mechanisms proposed by the Charlson et al (1987) hypothesis, that increasing global temperatures will lead to increased ventilation of DMS from the ocean to the atmosphere. The study develops one-dimensional biogeochemical models of DMS production by upper ocean ecosystems, based on the model proposed by Gabric et al. (1993b). The models are examined to elucidate their fundamental mathematical properties, and are subjected to sensitivity analysis to identify important processes and parameters. These investigations identify a simpler model that can reproduce the predictions of the Gabric et al. (1993b) model. Predictions derived from model simulations forced by climatologies of measured physical data are compared to a global database of measurements of sea surface DMS concentrations, and to observed depth profiles of DMS in the upper ocean. These comparisons confirm that all models are in good qualitative agreement with measured data. The fifteen global climate prediction models currently in use around the globe all predict substantial warming effects from the ventilation of anthropogenic carbon dioxide to the atmosphere. A simplified DMS model is calibrated to climatologies of Antarctic chlorophyll and DMS data and reproduces the data with great precision. The calibrated model is applied in global warming scenarios to 'test' the efficacy of the mechanism proposed by the Charlson et al (1987) hypothesis. This simulation provides evidence that the response predicted by the hypothesis is indeed feasible, and that substantial increases (up to 45%) in the ventilation of DMS to the atmosphere could be possible in some circumstances. The results of the modelling study provide impetus for further examination of field data. If couplings between marine biota and atmosphere are feasible, then they may be operating contemporarily, and may be detectable. Atmospheric DMS is oxidised to form aerosols (Miller et al. 2002) that influence the aerosol optical depth of the atmosphere. Archives of remote sensed ocean chlorophyll a concentration and aerosol optical depth are examined for evidence of the biologically mediated couplings. A clear coupling between aeolian dust and marine phytoplankton is evident from this analysis, suggesting that the deposition of dust from the atmosphere is a major factor controlling phytoplankton growth in many parts of the ocean. A second coupling between marine phytoplankton and atmospheric aerosols is also detected. This coupling is apparently not related to dust and is symmetrical about the equator, despite the substantial differences in the atmospheres and oceans of each hemisphere. It is speculated that this coupling may reflect the influence of the ventilation of DMS produced by marine phytoplankton on the atmosphere. This thesis provides new evidence supporting the important role of marine ecosystems in global climate regulation by the production of DMS. This evidence is principally obtained from a biogeochemical modelling approach, but is supported by analyses of empirical data. The concordance of results obtained from different approaches suggests that the contribution of marine ecosystems to global climate regulation is real, important and currently active.

Estilos ABNT, Harvard, Vancouver, APA, etc.

Saario, Seppo Aukusti, e n/a. "FDTD Modelling For Wireless Communications: Antennas and Materials". Griffith University. School of Microelectronic Engineering, 2003. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20030602.101319.

Texto completo da fonte

Resumo:

The application of the finite-difference time-domain (FDTD) method for the numerical analysis of complex electromagnetic problems related to wireless communications is considered. Since exact solutions to many complex electromagnetic problems are difficult, if not impossible, the FDTD method is well suited to modelling a wide range of electromagnetic problems. Structures considered include single and twin-slot antennas for millimetre-wave applications, monopole antennas on mobile handsets and chokes for the suppression of currents on coaxial cables. Memory efficient techniques were implemented for the split-field perfectly matched layer (PML) absorbing boundary condition. The frequency-domain far-field transformations were used for the calculation of far-field radiation patterns. Dipole, slot and mobile handset antenna benchmark problems verified the accuracy of the FDTD implementation. The application of slot antennas for millimetre-wave imaging arrays was investigated. An optimal feed network for an offset-fed single-slot antenna was designed for the X band with numerical and experimental results in excellent agreement. A twin-slot antenna structure reduced surface wave coupling by 7.6 dB in the substrate between coplanar waveguide-fed slot antenna elements in a planar array. The reduction of substrate surface waves for the twin-slot antenna allows for closer element spacings with less radiation pattern degradation in array applications. Suppression techniques for currents flowing on the exterior surface of coaxial cables were investigated. These include the use of ferrite beads and a quarter-wave sleeve balun. The frequency dependent behaviour of ferrite based chokes showed highly resonant effects which resulted in less than 5 dB of isolation at the resonant frequencies of the bead. An analysis of air-gaps between the ferrite bead and cable are shown to be extremely detrimental in the isolation characteristics of ferrite bead chokes. An air-gap of 0.5 mm can reduce the isolation effectiveness of a bead by 20 dB. The first rigorous analysis of a quarter-wave sleeve balun is presented, enabling an optimal choke design for maximum isolation. A standard 0.25[symbols] sleeve balun achieved 10.9 dB isolation with [symbols]=4, whereas a choke of optimal length 0.232[symbols] had an isolation of better than -20 dB. Several techniques for the measurement of antenna characteristics of battery powered handsets were compared and perturbation effects associated with the direct connection of a coaxial cable to a mobile handset was quantified. Significant perturbation in both return loss and radiation pattern can occur depending on cable location on the handset chassis. The effectiveness of ferrite chokes in any location was marginal. However, the application of an optimal quarter-wave sleeve balun in the centre of the largest plane of the handset, orthogonal to the primary polarisation resulted in minimal perturbation of both radiation patterns and return loss.

Estilos ABNT, Harvard, Vancouver, APA, etc.

Pham, Duc Nghia, e n/a. "Modelling and Exploiting Structures in Solving Propositional Satisfiability Problems". Griffith University. Institute for Integrated and Intelligent Systems, 2006. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20070216.143447.

Texto completo da fonte

Resumo:

Recent research has shown that it is often preferable to encode real-world problems as propositional satisfiability (SAT) problems and then solve using a general purpose SAT solver. However, much of the valuable information and structure of these realistic problems is flattened out and hidden inside the corresponding Conjunctive Normal Form (CNF) encodings of the SAT domain. Recently, systematic SAT solvers have been progressively improved and are now able to solve many highly structured practical problems containing millions of clauses. In contrast, state-of-the-art Stochastic Local Search (SLS) solvers still have difficulty in solving structured problems, apparently because they are unable to exploit hidden structure as well as the systematic solvers. In this thesis, we study and evaluate different ways to effectively recognise, model and efficiently exploit useful structures hidden in realistic problems. A summary of the main contributions is as follows: 1. We first investigate an off-line processing phase that applies resolution-based pre-processors to input formulas before running SLS solvers on these problems. We report an extensive empirical examination of the impact of SAT pre-processing on the performance of contemporary SLS techniques. It emerges that while all the solvers examined do indeed benefit from pre-processing, the effects of different pre-processors are far from uniform across solvers and across problems. Our results suggest that SLS solvers need to be equipped with multiple pre-processors if they are ever to match the performance of systematic solvers on highly structured problems. [Part of this study was published at the AAAI-05 conference]. 2. We then look at potential approaches to bridging the gap between SAT and constraint satisfaction problem (CSP) formalisms. One approach has been to develop a many-valued SAT formalism (MV-SAT) as an intermediate paradigm between SAT and CSP, and then to translate existing highly efficient SAT solvers to the MV-SAT domain. In this study, we follow a different route, developing SAT solvers that can automatically recognise CSP structure hidden in SAT encodings. This allows us to look more closely at how constraint weighting can be implemented in the SAT and CSP domains. Our experimental results show that a SAT-based mechanism to handle weights, together with a CSP-based method to instantiate variables, is superior to other combinations of SAT and CSP-based approaches. In addition, SLS solvers based on this many-valued weighting approach outperform other existing approaches to handle many-valued CSP structures. [Part of this study was published at the AAAI-05 conference]. 3. Finally, we propose and evaluate six different schemes to encode temporal reasoning problems, in particular the Interval Algebra (IA) networks, into SAT CNF formulas. We then empirically examine the performance of local search as well as systematic solvers on the new temporal SAT representations, in comparison with solvers that operate on native IA representations. Our empirical results show that zChaff (a state-of-the-art complete SAT solver) together with the best IA-to-SAT encoding scheme, can solve temporal problems significantly faster than existing IA solvers working on the equivalent native IA networks. [Part of this study was published at the CP-05 workshop].

Estilos ABNT, Harvard, Vancouver, APA, etc.

Mais fontes

Livros sobre o assunto "Root modelling"

Leybourne, Stephen J. Randomized unit root processes for modelling and forecasting financial time series: Theory and applications. Loughborough: Loughborough University of Technology, Department of Economics, 1995.

Encontre o texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

L, Ahuja, ed. Root zone water quality model: Modelling management effects on water quality and crop production. Highlands Ranch, Colo: Water Resources Publications, 2000.

Encontre o texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Sciavicco, Lorenzo, e Bruno Siciliano. Modelling and Control of Robot Manipulators. London: Springer London, 2000. http://dx.doi.org/10.1007/978-1-4471-0449-0.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Ghafil, Hazim Nasir, e Károly Jármai. Optimization for Robot Modelling with MATLAB. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-40410-9.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Megahed, Saïd M. Principles of robot modelling and simulation. Chichester: Wiley, 1993.

Encontre o texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Megahed, Saïd M. Principles of robot modelling and simulation. Chichester: J. Wiley, 1993.

Encontre o texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

1959-, Siciliano Bruno, ed. Modelling and control of robot manipulators. London: Springer, 2000.

Encontre o texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Nehmzow, Ulrich. Robot behaviour: Design, description, analysis and modelling. London: Springer, 2009.

Encontre o texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

1933-, Ho C. Y., ed. Robot modelling: Control and applications with software. Kempston, Bedford, England: IFS (Publications), 1985.

Encontre o texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Nehmzow, Ulrich. Robot behaviour: Design, description, analysis and modelling. London: Springer, 2009.

Encontre o texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Mais fontes

Capítulos de livros sobre o assunto "Root modelling"

de Willigen, P., N. E. Nielsen, N. Claassen e A. M. Castrignanò. "Modelling Water and Nutrient Uptake". In Root Methods, 509–43. Berlin, Heidelberg: Springer Berlin Heidelberg, 2000. http://dx.doi.org/10.1007/978-3-662-04188-8_15.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Pagès, L., S. Asseng, S. Pellerin e A. Diggle. "Modelling Root System Growth and Architecture". In Root Methods, 113–46. Berlin, Heidelberg: Springer Berlin Heidelberg, 2000. http://dx.doi.org/10.1007/978-3-662-04188-8_4.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Khoury, Richard, e Douglas Wilhelm Harder. "Root-Finding". In Numerical Methods and Modelling for Engineering, 119–56. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-21176-3_8.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Fischer, W., H. Eckert, D. Längle e K. Geissendörfer. "Root Modelling Interface (RMI)". In GI/OCG/ÖGI-Jahrestagung 1985, 439–49. Berlin, Heidelberg: Springer Berlin Heidelberg, 1985. http://dx.doi.org/10.1007/978-3-642-70639-4_39.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Beelitz, Reiner, Julius Blencke, Stefan Liczkowski e Andreas Woyke. "Rhizome - Parametric Design Inspired by Root Based Linking Structures". In Computational Design Modelling, 327–34. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-23435-4_37.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Kirk, G. J. D. "Modelling root-induced solubilization of nutrients". In Food Security in Nutrient-Stressed Environments: Exploiting Plants’ Genetic Capabilities, 155–63. Dordrecht: Springer Netherlands, 2002. http://dx.doi.org/10.1007/978-94-017-1570-6_17.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Świtała, Barbara M., e E. James Fern. "Modelling Root-reinforced Soils with Nor-Sand". In Springer Series in Geomechanics and Geoengineering, 79–83. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-97112-4_18.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Gahoonia, T. S., e N. E. Nielsen. "Measuring and modelling phosphorus uptake by root hairs". In Plant Nutrition, 534–35. Dordrecht: Springer Netherlands, 2001. http://dx.doi.org/10.1007/0-306-47624-x_258.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Kogelschatz, Hartmut Martin. "Bounds for the Frobenius Root of Non-Negative Matrices and an Economic Application". In Mathematical Modelling in Economics, 243–48. Berlin, Heidelberg: Springer Berlin Heidelberg, 1993. http://dx.doi.org/10.1007/978-3-642-78508-5_23.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Ouliaris, Sam, Joon Y. Park e Peter C. B. Phillips. "Testing for a Unit Root in the Presence of a Maintained Trend". In Advances in Econometrics and Modelling, 7–28. Dordrecht: Springer Netherlands, 1989. http://dx.doi.org/10.1007/978-94-015-7819-6_2.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Trabalhos de conferências sobre o assunto "Root modelling"

Grusho, Alexander A., Nick A. Grusho, Michael I. Zabezhailo, Elena E. Timonina e Vladimir V. Senchilo. "Metadata For Root Cause Analysis". In 35th ECMS International Conference on Modelling and Simulation. ECMS, 2021. http://dx.doi.org/10.7148/2021-0267.

Texto completo da fonte

Resumo:

The paper is devoted to the task of finding the root cause of anomaly in a distributed information and computing system. An approximate approach is considered to detect implicit anomalies with accuracy to the object (of a component of the technical device, a node of a network infrastructure, an application or of an information resource). The approximate solution is based on the use of integral parameters that allow you to identify an anomaly, but do not allow you to indicate its cause. To work with such methods for determining the root causes of anomalies, auxiliary data is required, which is called metadata in the work. The work describes a metadata construction algorithm and shows ways of using metadata to build an object in which the root cause of the anomaly is located. An approximate solution to the problem of finding the root cause of an anomaly with a help of quickly computable values of integral parameters is necessary to reduce the time of interruption of work processes due to implicit anomalies. It is assumed that small subsystems and nodes are easier to replace than to delve into the study of the cause.

Estilos ABNT, Harvard, Vancouver, APA, etc.

"Root zone soil moisture estimation over China". In 25th International Congress on Modelling and Simulation. Modelling and Simulation Society of Australia and New Zealand, 2023. http://dx.doi.org/10.36334/modsim.2023.tian218.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Dupuy, Lionel X., Theodore E. Simos, George Psihoyios, Ch Tsitouras e Zacharias Anastassi. "Modelling Root Systems Using Oriented Density Distributions". In NUMERICAL ANALYSIS AND APPLIED MATHEMATICS ICNAAM 2011: International Conference on Numerical Analysis and Applied Mathematics. AIP, 2011. http://dx.doi.org/10.1063/1.3636834.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Meng, Zhiqiang (David), Richard Bluck e Björn Sjödin. "Probabilistic Modelling Geometric Tolerance and LCF Life of Gas Turbine Compressor Blade". In ASME Turbo Expo 2024: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2024. http://dx.doi.org/10.1115/gt2024-127340.

Texto completo da fonte

Resumo:

Abstract This paper presents a probabilistic LCF assessment for geometric tolerances on high load contact surfaces of gas turbine compressor blades. The typical patterns of the geometric deviations for the root contact flank of the compressor blades are identified and characterized according to CMM measurements of the blade root. These typical patterns are closely related to the root form manufacture tools and process. FE models for the typical geometric deviation patterns are created based on nodal coordinates transformation of the surface nodes on the blade root contact flanks and radius. An optimized blade root profile tolerance is established, which enables significant cost saving. The elastic-plastic FE analysis with nonlinear contact model, material strain-life test, response surface and constrained Monte Carlo simulation are used to create a probabilistic LCF life model for the optimized tolerance. The model quantifies the effect of the geometric deviations, blade mass and material property on the blade LCF life. The result shows that with the optimized tolerance, the probability of blade LCF failure is very low and acceptable. It is also shown that the strain life material property is the most critical factor for the LCF failure. The root profile tolerance and blade mass are seen to have a much weaker effect on the blade LCF life.

Estilos ABNT, Harvard, Vancouver, APA, etc.

Koscso, Adam, e E. P. Petrov. "Blade Root Joint Modelling and Analysis of Effects of Their Geometry Variability on the Nonlinear Forced Response of Tuned and Mistuned Bladed Disks". In ASME Turbo Expo 2020: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/gt2020-15225.

Texto completo da fonte

Resumo:

Abstract One of the major sources of the damping of the forced vibration for bladed disk structures is the micro-slip motion at the contact interfaces of blade-disk joints. In this paper, the modeling strategies of nonlinear contact interactions at blade roots are examined using high-fidelity modelling of bladed disk assemblies and the nonlinear contact interactions at blade-disk contact patches. The analysis is performed in the frequency domain using multiharmonic harmonic balance method and analytically formulated node-to-node contact elements modelling frictional and gap nonlinear interactions. The effect of the number, location and distribution of nonlinear contact elements are analyzed using cyclically symmetric bladed disks. The possibility of using the number of the contact elements noticeably smaller than the total number of nodes in the finite element mesh created at the contact interface for the high-fidelity bladed disk model is demonstrated. The parameters for the modeling of the root damping are analysed for tuned and mistuned bladed disks. The geometric shapes of blade roots and corresponding slots in disks cannot be manufactured perfectly and there is inevitable root joint geometry variability within the manufacturing tolerances. Based on these tolerances, the extreme cases of the geometry variation are defined and the assessment of the possible effects of the root geometry variation on the nonlinear forced response are performed based on a set of these extreme cases.

Estilos ABNT, Harvard, Vancouver, APA, etc.

Mary, Benjamin, Vicente Burchard-Levine, Miguel Ángel Herrezuelo e Héctor Nieto. "Monitoring and modelling root-zone processes with geoelectrical methods". In Agriculture and geophysics: Illuminating the subsurface. Agrogeophysics, 2024. http://dx.doi.org/10.62329/ugjk2874.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Narayan, Subrahmanya Keremane, Viren S. Ram e Rajshekhar Gannavarpu. "Conditional generative modelling based fringe pattern normalization". In 3D Image Acquisition and Display: Technology, Perception and Applications. Washington, D.C.: Optica Publishing Group, 2023. http://dx.doi.org/10.1364/3d.2023.jw2a.25.

Texto completo da fonte

Resumo:

In this article, we propose a generative adversarial network based fringe pattern normalization method. We investigate the method's effectiveness under various noise levels by evaluating root mean square error (RMSE) and structural similarity index measure (SSIM).

Estilos ABNT, Harvard, Vancouver, APA, etc.

"3D reconstruction, modelling and analysis of in situ root system architecture". In 20th International Congress on Modelling and Simulation (MODSIM2013). Modelling and Simulation Society of Australia and New Zealand (MSSANZ), Inc., 2013. http://dx.doi.org/10.36334/modsim.2013.b1.kumar.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

"Plant root architecture: A trade-off between tolerance to competitors and potential growth". In 25th International Congress on Modelling and Simulation. Modelling and Simulation Society of Australia and New Zealand, 2023. http://dx.doi.org/10.36334/modsim.2023.salinas.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Jelaska, Damir T., Srecko Glodez e Srdjan Podrug. "Numerical Modelling of the Crack Propagation Path at Gear Tooth Root". In ASME 2003 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/detc2003/ptg-48026.

Texto completo da fonte

Resumo:

A numerical model for determination of service life of gears in regard to bending fatigue in a gear tooth root is presented. The Coffin-Manson relationship is used to determine the number of stress cycles Ni required for the fatigue crack initiation, where it is assumed that the initial crack is located at the point of the largest stresses in a gear tooth root. The simply Paris equation is then used for the further simulation of the fatigue crack growth, where required material parameters have been determined previously by the appropriate test specimens. The functional relationship between the stress intensity factor and crack length K = f(a), which is needed for determination of the required number of loading cycles Np for a crack propagation from the initial to the critical length, is obtained numerically. The total number of stress cycles N for the final failure to occur is then a sum N = Ni + Np. Although some influences were not taken into account in the computational simulations, the presented model seems to be very suitable for determination of service life of gears because numerical procedures used here are much faster and cheaper if compared with the experimental testing.

Estilos ABNT, Harvard, Vancouver, APA, etc.

Relatórios de organizações sobre o assunto "Root modelling"

Zhang, Xingyu, Matteo Ciantia, Jonathan Knappett e Anthony Leung. Micromechanical study of potential scale effects in small-scale modelling of sinker tree roots. University of Dundee, dezembro de 2021. http://dx.doi.org/10.20933/100001235.

Texto completo da fonte

Resumo:

When testing an 1:N geotechnical structure in the centrifuge, it is desirable to choose a large scale factor (N) that can fit the small-scale model in a model container and avoid unwanted boundary effects, however, this in turn may cause scale effects when the structure is overscaled. This is more significant when it comes to small-scale modelling of sinker root-soil interaction, where root-particle size ratio is much lower. In this study the Distinct Element Method (DEM) is used to investigate this problem. The sinker root of a model root system under axial loading was analysed, with both upward and downward behaviour compared with the Finite Element Method (FEM), where the soil is modelled as a continuum in which case particle-size effects are not taken into consideration. Based on the scaling law, with the same prototype scale and particle size distribution, different scale factors/g-levels were applied to quantify effects of the ratio of root diameter (𝑑𝑟) to mean particle size (𝐷50) on the root rootsoil interaction.

Estilos ABNT, Harvard, Vancouver, APA, etc.

Linkins, A. E. Modelling regulation of decomposition and related root/mycorrhizal processes in arctic tundra soils. Office of Scientific and Technical Information (OSTI), janeiro de 1992. http://dx.doi.org/10.2172/7263706.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Eberlein, Robert, e Sven Düzel. Fatigue lifetime analysis of POM gears for generalized tooth root shapes. Universidad de los Andes, dezembro de 2024. https://doi.org/10.51573/andes.pps39.gs.ms.1.

Texto completo da fonte

Resumo:

The current calculation methods for determining the tooth root load capacity of polymer gears (e.g., VDI 2736) are based on the same assumptions as those for steel gears. However, due to the non-linear material behavior, temperature, and rate dependency of polymers, these predictions are often inaccurate. A previous study employed rate-dependent nonlinear viscoplastic finite element (FE) modelling of polyoxymethylene (POM) to quantify material influences not considered in standard metal gear assumptions. A lifetime model was developed and validated to predict tooth root fracture based on rotational speed for a constant tooth root geometry. In this study, the existing damage model is adapted and validated to include the dependency on notch (tooth root) geometry. The extension of the model to two damage parameters allows for a geometry-independent representation of the nonlinear speed dependency of tooth root breakage. This correlative modelling approach incorporates two independent damage mechanisms inside the material which lead to tooth root breakage failure of the gear. To map these mechanisms, local material states at the crack initiation point are used as damage parameters. Calibration of the bi-parametric damage model with experimental data shows that model predictions fall within the experimental scatter. Further research is ongoing to extend the damage model regarding generalized torque loading conditions.

Estilos ABNT, Harvard, Vancouver, APA, etc.

Linkins, A. E. Modelling regulation of decomposition and related root/mycorrhizal processes in arctic tundra soils. Final report. Office of Scientific and Technical Information (OSTI), setembro de 1992. http://dx.doi.org/10.2172/10178205.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Dinovitzer, Aaron. PR-214-144500-R01 Weld Hydrogen Cracking Susceptibility Characterization. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), março de 2016. http://dx.doi.org/10.55274/r0010924.

Texto completo da fonte

Resumo:

Hydrogen cracking has been and continues to be observed in both heat-affected zones and weld metals. High carbon equivalent weldment heat-affected zones (HAZ) combined with rapid cooling have been related to the development of hydrogen cracking susceptible microstructures. Weld metal cracking is observed in both high and low strength weldments and is a particular concern for root passes due to the use of cellulosic electrodes, parent metal dilution, applied load, and weld fault stress riser effects promoting cracking. The risk of HAZ and weld cracking are increased for repair and in-service welds and/or welds deposited on older generation materials (e.g., pipe or fittings) and this can pose a significant risk to the integrity of welded connections. This report presents the result of the first year of research toward the application and extension of the �Slow Bend� testing technique used to quantify the hydrogen cracking susceptibility of a weldment. This testing is being used to quantify the susceptibility of a microstructure to hydro-gen cracking by defining the critical combinations of strain and hydrogen concentration that result in cracking in a given material. The testing and modelling results complete in this first year of work are planned to support the definition of a Hydrogen Embrittlement characterization technique considering the effects of strain and hydrogen concentration for a material.

Estilos ABNT, Harvard, Vancouver, APA, etc.

Tatlicioglu, E., Ian D. Walker e Darren M. Dawson. Dynamic Modelling for Planar Extensible Continuum Robot Manipulators. Fort Belvoir, VA: Defense Technical Information Center, janeiro de 2006. http://dx.doi.org/10.21236/ada462495.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Dinovitzer, Aaron. PR-214-144500-R05 Weld Hydrogen Cracking Susceptibility Characterization. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), julho de 2018. http://dx.doi.org/10.55274/r0011495.

Texto completo da fonte

Resumo:

Hydrogen cracking has been and continues to be observed in both heat-affected zones and weld metals. High carbon equivalent weldment heat-affected zones (HAZ) combined with rapid cooling have been related to the development of hydrogen cracking susceptible microstructures. Weld metal cracking is observed in both high and low strength weldments and is a particular concern for root passes due to the use of cellulosic electrodes, parent metal dilution, applied load, and weld fault stress riser effects promoting cracking. The risk of HAZ and weld cracking are increased for repair and in-service welds and/or welds deposited on older generation materials (e.g., pipe or fittings) and this can pose a significant risk to the integrity of welded connections. This report presents the result of research in the application and extension of the "Slow Bend" testing technique used to quantify the hydrogen cracking susceptibility of a weldment. This testing is being used to quantify the susceptibility of a microstructure to hydrogen cracking by defining the critical combinations of strain and hydrogen concentration (i.e. hydrogen embrittlement curves) that result in cracking in a given material. The testing and modelling results have been used to define relationships between the hydrogen embrittlement curve parameters (i.e. ductility and hydrogen embrittlement indices) and the properties of the deposited weld metal. These preliminary relationships were defined separately for cellulosic and basic SMAW electrodes providing insight to the factors that make a weld material susceptible to hydrogen cracking.

Estilos ABNT, Harvard, Vancouver, APA, etc.

Yu, Y. S. Capabilities, limitations and the use of the GEOROC computer package. Natural Resources Canada/CMSS/Information Management, 1987. http://dx.doi.org/10.4095/325534.

Texto completo da fonte

Resumo:

Computer codes have been used by various researchers in modelling viscoelastic formations, with a good degree of success. Serata used a complex rheological model, REM (Rheological Element Model) code, to simulate mine openings [2]. Others, in the U.S. Nuclear Waste Isolation Programme, have evaluated the capability of various codes for the design of nuclear waste repository [3]. Because of the proprietary nature of the above codes, they are not available to mine operators in Canada. Consequently, in 1984, CANMET initiated a research project to develop a numerical modelling package for use in the design of underground potash mine openings. GEOROC is the resultant computer program; it was developed by RE/SPEC Ltd., of Calgary under contract to CANMET. In recent years, computer simulation is playing an increasingly important role in evaluating the short and long term structural stability of underground mine openings, and in ground control studies related to mine design and layout. Such simulations are increasingly being used in the design of underground salt and potash mines. Because of the viscoelastic nature of salt rock formations, simulation models must take into consideration their time dependent properties if they are to correctly predict opening closures, ground stresses, and ground stability based on prescribed failure criteria. This presentation describes the capabilities, limitations and the use of computer code - GEOROC. A case history in which GEOROC is used to simulate a typical room and pillar mining section of a Western Canadian potash mine is provided. Predicted ground behaviour using the code is compared with actual behaviour as determined through field measurements. Results indicate that good correlation exits between predicted and measured ground behaviour, and is an encouragement to greater use of modelling in mine stability studies related to mine design.

Estilos ABNT, Harvard, Vancouver, APA, etc.

Davies, Will. Improving the engagement of UK armed forces overseas. Royal Institute of International Affairs, janeiro de 2022. http://dx.doi.org/10.55317/9781784135010.

Texto completo da fonte

Resumo:

The UK government’s Integrated Review of security, defence, development and foreign policy, published in March 2021 alongside a supporting defence command paper, set a new course for UK national security and highlighted opportunities for an innovative approach to international engagement activity. The Integrated Review focused principally on the state threats posed by China’s increasing power and by competitors – including Russia – armed with nuclear, conventional and hybrid capabilities. It also stressed the continuing risks to global security and resilience due to conflict and instability in weakened and failed states. These threats have the potential to increase poverty and inequality, violent extremism, climate degradation and the forced displacement of people, while presenting authoritarian competitors with opportunities to enhance their geopolitical influence. There are moral, security and economic motives to foster durable peace in conflict-prone and weakened regions through a peacebuilding approach that promotes good governance, addresses the root causes of conflict and prevents violence, while denying opportunities to state competitors. The recent withdrawal from Afghanistan serves to emphasize the complexities and potential pitfalls associated with intervention operations in complex, unstable regions. Success in the future will require the full, sustained and coordinated integration of national, allied and regional levers of power underpinned by a sophisticated understanding of the operating environment. The UK armed forces, with their considerable resources and global network, will contribute to this effort through ‘persistent engagement’. This is a new approach to overseas operations below the threshold of conflict, designed as a pre-emptive complement to warfighting. To achieve this, the UK Ministry of Defence (MOD) must develop a capability that can operate effectively in weak, unstable and complex regions prone to violent conflict and crises, not least in the regions on the eastern and southern flanks of the Euro-Atlantic area. The first step must be the development of a cohort of military personnel with enhanced, tailored levels of knowledge, skills and experience. Engagement roles must be filled by operators with specialist knowledge, skills and experience forged beyond the mainstream discipline of combat and warfighting. Only then will individuals develop a genuinely sophisticated understanding of complex, politically driven and sensitive operating environments and be able to infuse the design and delivery of international activities with practical wisdom and insight. Engagement personnel need to be equipped with: An inherent understanding of the human and political dimensions of conflict, the underlying drivers such as inequality and scarcity, and the exacerbating factors such as climate change and migration; - A grounding in social sciences and conflict modelling in order to understand complex human terrain; - Regional expertise enabled by language skills, cultural intelligence and human networks; - Familiarity with a diverse range of partners, allies and local actors and their approaches; - Expertise in building partner capacity and applying defence capabilities to deliver stability and peace; - A grasp of emerging artificial intelligence technology as a tool to understand human terrain; - Reach and insight developed through ‘knowledge networks’ of external experts in academia, think-tanks and NGOs. Successful change will be dependent on strong and overt advocacy by the MOD’s senior leadership and a revised set of personnel policies and procedures for this cohort’s selection, education, training, career management, incentivization, sustainability and support.

Estilos ABNT, Harvard, Vancouver, APA, etc.

Dasberg, Shmuel, Jan W. Hopmans, Larry J. Schwankl e Dani Or. Drip Irrigation Management by TDR Monitoring of Soil Water and Solute Distribution. United States Department of Agriculture, agosto de 1993. http://dx.doi.org/10.32747/1993.7568095.bard.

Texto completo da fonte

Resumo:

Drip irrigation has the potential of high water use efficiency, but actual water measurement is difficult because of the limited wetted volume. Two long-term experiments in orchards in Israel and in California and several field crop studies supported by this project have demonstrated the feasibility of precise monitoring of soil water distribution for drip irrigation in spite of the limited soil wetting. Time Domain Reflectometry (TDR) enables in situ measurement of soil water content of well defined small volumes. Several approaches were tried in monitoring the soil water balance in the field during drip irrigation. These also facilitated the estimation of water uptake: 1. The use of multilevel moisture probe TDR system. This approach proved to be of limited value because of the extremely small diameter of measurement. 2. The placement of 20 cm long TDR probes at predetermined distances from the drippers in citrus orchards. 3. Heavy instrumentation with neutron scattering access tubes and tensiometers of a single drip irrigated almond tree. 4. High resolution spatial and temporal measurements (0.1m x 0.1m grid) of water content by TDR in corn irrigated by surface and subsurface drip. The latter approach was accompanied by parametric modelling of water uptake intensity patterns by corn roots and superimposed with analytical solutions for water flow from point and line sources. All this lead to general and physically based suggestions for the placement of soil water sensors for scheduling drip irrigation.

Estilos ABNT, Harvard, Vancouver, APA, etc.

Oferecemos descontos em todos os planos premium para autores cujas obras estão incluídas em seleções literárias temáticas. Contate-nos para obter um código promocional único!