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This paper describes a robust and efficient methodology for predicting displacements, deformations, and stresses in geomaterials that are susceptible to creep. The methodology is based on two integration schemes, which consider substepping algorithms. The first scheme is used for integrating space-time relations in a global sense, whereas the second scheme is used for integrating stress-stain relations in a local sense. Different from previous studies, both integration schemes are easy to implement and general in the sense that they can be applied to any type of creep law. Through an in-house finite element simulator, several numerical tests are performed. They include triaxial and wellbore closure analyses considering soft soils and salt rocks. The results show that the combination of both schemes leads to stable and accurate solutions with reduced computational time. 相似文献
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Alessandro Chiodi Trevor Donnellan James Breen Paul Deane Kevin Hanrahan Maurizio Gargiulo 《Climate Policy》2016,16(2):215-236
Agriculture is responsible for approximately 25% of anthropogenic global GHG emissions. This significant share highlights the fundamental importance of the agricultural sector in the global GHG emissions reduction challenge. This article develops and tests a methodology for the integration of agricultural and energy systems modelling. The goal of the research is to extend an energy systems modelling approach to agriculture in order to provide richer insights into the dynamics and interactions between the two (e.g. in competition for land-use). We build Agri-TIMES, an agricultural systems module using the TIMES energy systems modelling framework, to model the effect of livestock emissions and explore emissions reduction options. The research focuses on Ireland, which is an interesting test case for two reasons: first, agriculture currently accounts for about 30% of Ireland's GHG emissions, significantly higher than other industrialized countries yet comparable with global levels (here including emissions associated with other land-use change and forestation); second, Ireland is both a complete and reasonably sized agricultural system to act as a test case for this new approach. This article describes the methodology used, the data requirements, and technical assumptions made to facilitate the modelling. It also presents results to illustrate the approach and provide associated initial insights.
Policy relevance
Most of the policy focus with regard to climate mitigation targets has been on reducing energy-related CO2 emissions, which is understandable as they represent by far the largest source of emissions. Non-energy-related GHG emissions – largely from agriculture, industrial processes, and waste – have received significantly less attention in policy discourse. Going forward, however, if significant cuts are made in energy-related CO2 emissions, the role of non-energy-related GHG emissions will grow in importance. It is therefore crucial that climate mitigation analyses and strategies are not limited to the energy system. This article shows the value of using integrated energy and agriculture techno-economic modelling techniques to draw evidence for new comprehensive climate policy strategies able to discern between the full range of technical solutions available. It enables the production of economy-wide least-cost climate mitigation pathways. 相似文献
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An assessment of the creep behaviour of Brazilian salt rocks using the multi-mechanism deformation model 总被引：1，自引：1，他引：0
Salt rocks are geomaterials that exhibit several peculiarities, which require a particular approach in rock mechanics. In the field, those rocks are usually found in layered/bedded deposits and in domes or similar structures. Creep is one of the main deformation mechanisms associated with salt rocks, and this phenomenon is highly dependent on the stress state, temperature and mineralogy. Salt rock mechanics for engineering applications requires the definition of a powerful constitutive model and this is an ongoing challenge. Among the many available models, one of the most sophisticated physical constitutive models for salt rocks is the multi-mechanism deformation creep model (MD model). The main contribution of this work is to present a first effort in the use of the MD model for Brazilian salt rocks. Material-sensitive parameters have been calibrated for the Brazilian halite through two methodologies. Salt is modelled as an elasto-viscoplastic material. Numerical simulations using the finite element method have been carried out for triaxial creep tests, Pre-salt wellbore closure and mining gallery convergence in order to validate the parameter set and the methodologies. Excellent results have been observed in most of the applications for validation. Even so, validation efforts should continue to consolidate the parameters and identify possible limitations. 相似文献
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We present upper limits on the 850-μm and 450-μm fluxes of the warm hyperluminous (bolometric luminosity galaxies IRAS P09104+4109 and IRAS F15307+3252 , derived from measurements using the SCUBA bolometer array on the James Clerk Maxwell Telescope. Hot luminous infrared sources like these are thought to differ from more normal cold ultraluminous infrared galaxies in that they derive most of their bolometric luminosities from dusty active galactic nuclei (AGNs) as opposed to starbursts. Such hot, dusty AGNs at high redshift are thought to be responsible for much of the mass accretion of the Universe that is in turn responsible for the formation of the supermassive black holes seen in the centres of local galaxies. The galaxy IRAS P09104+4109 is also unusual in that it is a cD galaxy in the centre of a substantial cooling-flow cluster, not an isolated interacting galaxy like most ultraluminous infrared galaxies. Previously it was known to have large amounts of hot dust from IRAS observations. We now show that the contribution of cold dust to the bolometric luminosity is less than 3 per cent. Most ultraluminous infrared galaxies possess large amounts of cold dust, and it is now known that some cooling-flow cluster cD galaxies do as well. Yet this object, which is an extreme example of both, does not have enough cold gas to contribute significantly to the bolometric luminosity. We outline physical reasons why this could have happened. We then provide a discussion of strategies for finding hot dusty AGNs, given the limitations on submillimetre surveys implied by this work. 相似文献
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Pedro A. L. P. Firme Nuno B. Brandao Deane Roehl Celso Romanel 《Acta Geotechnica》2018,13(6):1329-1340
The double-mechanism creep law (DM model) is an empirical creep constitutive model widely employed in Brazilian salt rock mechanics. This model often presents good performance in steady-state creep prediction. However, transient creep is not accounted for, and whenever early creep estimates are important, the contribution of this phase might be meaningful. This work adds value by presenting two alternatives to account for transient creep in the DM model. The first alternative couples the transient function from Sandia’s multi-mechanism deformation model to the DM model steady-state creep rate (EDMT model). The second alternative couples the DM model response to Norton’s power law when the strain rate given by the latter remains lower than the one from the former (EDMP model). These models can be implemented in numerical simulators at small code extensions of the DM model implementations. Applications from previous works by the authors are revisited to validate the formulations based on experimental data. EDMT and EDMP models differ in the formulation of transient creep and, consequently, in the time of transition between the transient and the steady-state phases. Both methods were successful in treating transient creep and in simulating experimental results. 相似文献
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An optical imaging system (BubbleCam) has been tested for the quantification of bubble distributions at high void fractions formed beneath breaking waves. The instrument consists of a CCD video camera, stroboscopic light source, and optics allowing adjustable magnification, a fixed imaging volume, and the resolution of bubbles 3 pixels in radius and larger (equivalent to a minimum bubble radius of about 200 μm in the test configuration). BubbleCam has been deployed in a shore-based configuration (data and power supplied via shore-connected cables) as well as an autonomous device in the open sea with its own power supply and data storage. The resulting images are processed using a variant of the Hough transform which allows computer-automated counting and measurement of the bubbles within the video frames. In addition, images can be qualitatively examined to provide insights into bubble plume evolution and creation mechanisms 相似文献
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Fast numerics for the spin orbit equation with realistic tidal dissipation and constant eccentricity
Michele Bartuccelli Jonathan Deane Guido Gentile 《Celestial Mechanics and Dynamical Astronomy》2017,128(4):453-473
We present an algorithm for the rapid numerical integration of a time-periodic ODE with a small dissipation term that is \(C^1\) in the velocity. Such an ODE arises as a model of spin–orbit coupling in a star/planet system, and the motivation for devising a fast algorithm for its solution comes from the desire to estimate probability of capture in various solutions, via Monte Carlo simulation: the integration times are very long, since we are interested in phenomena occurring on timescales of the order of \(10^6\)–\(10^7\) years. The proposed algorithm is based on the high-order Euler method which was described in Bartuccelli et al. (Celest Mech Dyn Astron 121(3):233–260, 2015), and it requires computer algebra to set up the code for its implementation. The payoff is an overall increase in speed by a factor of about 7.5 compared to standard numerical methods. Means for accelerating the purely numerical computation are also discussed. 相似文献
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James Glynn Maurizio Gargiulo Alessandro Chiodi Paul Deane Fionn Rogan Brian Ó Gallachóir 《Climate Policy》2019,19(1):30-42
The Paris Agreement is the last hope to keep global temperature rise below 2°C. The consensus agrees to holding the increase in global average temperature to well below 2°C above pre-industrial levels, and to aim for 1.5°C. Each Party’s successive nationally determined contribution (NDC) will represent a progression beyond the party’s then current NDC, and reflect its highest possible ambition. Using Ireland as a test case, we show that increased mitigation ambition is required to meet the Paris Agreement goals in contrast to current EU policy goals of an 80–95% reduction by 2050. For the 1.5°C consistent carbon budgets, the technically feasible scenarios' abatement costs rise to greater than €8,100/tCO2 by 2050. The greatest economic impact is in the short term. Annual GDP growth rates in the period to 2020 reduce from 4% to 2.2% in the 1.5°C scenario. While aiming for net zero emissions beyond 2050, investment decisions in the next 5–10 years are critical to prevent carbon lock-in.
Key policy insights
Economic growth can be maintained in Ireland while rapidly decarbonizing the energy system.
The social cost of carbon needs to be included as standard in valuation of infrastructure investment planning, both by government finance departments and private investors.
Technological feasibility is not the limiting factor in achieving rapid deep decarbonization.
Immediate increased decarbonization ambition over the next 3–5 years is critical to achieve the Paris Agreement goals, acknowledging the current 80–95% reduction target is not consistent with temperature goals of ‘well below’ 2°C and pursuing 1.5°C.
Applying carbon budgets to the energy system results in non-linear CO2 emissions reductions over time, which contrast with current EU policy targets, and the implied optimal climate policy and mitigation investment strategy.