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Статті в журналах з теми "Scale-by-scale energy transfer"
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Hao, Keli, Koji Nagata, and Yi Zhou. "Scale-by-scale energy transfer in a dual-plane jet flow." Physics of Fluids 32, no. 10 (October 1, 2020): 105107. http://dx.doi.org/10.1063/5.0022103.
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Togni, Riccardo, Andrea Cimarelli, and Elisabetta De Angelis. "Physical and scale-by-scale analysis of Rayleigh–Bénard convection." Journal of Fluid Mechanics 782 (October 8, 2015): 380–404. http://dx.doi.org/10.1017/jfm.2015.547.
Повний текст джерелаАнотація:
A novel approach for the study of turbulent Rayleigh–Bénard convection (RBC) in the compound physical/scale space domain is presented. All data come from direct numerical simulations of turbulent RBC in a laterally unbounded domain confined between two horizontal walls, for Prandtl number $0.7$ and Rayleigh numbers $1.7\times 10^{5}$, $1.0\times 10^{6}$ and $1.0\times 10^{7}$. A preliminary analysis of the flow topology focuses on the events of impingement and emission of thermal plumes, which are identified here in terms of the horizontal divergence of the instantaneous velocity field. The flow dynamics is then described in more detail in terms of turbulent kinetic energy and temperature variance budgets. Three distinct regions where turbulent fluctuations are produced, transferred and finally dissipated are identified: a bulk region, a transitional layer and a boundary layer. A description of turbulent RBC dynamics in both physical and scale space is finally presented, completing the classic single-point balances. Detailed scale-by-scale budgets for the second-order velocity and temperature structure functions are shown for different geometrical locations. An unexpected behaviour is observed in both the viscous and thermal transitional layers consisting of a diffusive reverse transfer from small to large scales of velocity and temperature fluctuations. Through the analysis of the instantaneous field in terms of the horizontal divergence, it is found that the enlargement of thermal plumes following the impingement represents the triggering mechanism which entails the reverse transfer. The coupling of this reverse transfer with the spatial transport towards the wall is an interesting mechanism found at the basis of some peculiar aspects of the flow. As an example, it is found that, during the impingement, the presence of the wall is felt by the plumes through the pressure field mainly at large scales. These and other peculiar aspects shed light on the role of thermal plumes in the self-sustained cycle of turbulence in RBC, and may have strong repercussions on both theoretical and modelling approaches to convective turbulence.
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Ngan, K., P. Bartello, and D. N. Straub. "Dissipation of Synoptic-Scale Flow by Small-Scale Turbulence." Journal of the Atmospheric Sciences 65, no. 3 (March 1, 2008): 766–91. http://dx.doi.org/10.1175/2007jas2265.1.
Повний текст джерелаАнотація:
Abstract Although it is now accepted that imbalance in the atmosphere and ocean is generic, the feedback of the unbalanced motion on the balanced flow has not received much attention. In this work the parameterization problem is examined in the context of rotating stratified turbulence, that is, with a nonhydrostatic Boussinesq model. Using the normal modes as a first approximation to the balanced and unbalanced flow, the growth of ageostrophic perturbations to the quasigeostrophic flow and the associated feedback are studied. For weak stratification, there are analogies with the three-dimensionalization of decaying 2D turbulence: the growth rate of the ageostrophic perturbation follows a linear estimate, geostrophic energy is extracted from the base flow, and the associated damping on the geostrophic base flow (the “eddy viscosity”) is peaked at large horizontal scales. For strong stratification, the transfer spectra and eddy viscosities maintain this structure if there is synoptic-scale motion and the buoyancy scale is adequately resolved. This has been confirmed for global Rossby and Froude numbers of O(0.1). Implications for atmospheric and oceanic modeling are discussed.
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Bengtsson, Lisa, Heiner Körnich, Erland Källén, and Gunilla Svensson. "Large-Scale Dynamical Response to Subgrid-Scale Organization Provided by Cellular Automata." Journal of the Atmospheric Sciences 68, no. 12 (December 1, 2011): 3132–44. http://dx.doi.org/10.1175/jas-d-10-05028.1.
Повний текст джерелаАнотація:
Abstract Because of the limited resolution of numerical weather prediction (NWP) models, subgrid-scale physical processes are parameterized and represented by gridbox means. However, some physical processes are better represented by a mean and its variance; a typical example is deep convection, with scales varying from individual updrafts to organized mesoscale systems. This study investigates, in an idealized setting, whether a cellular automaton (CA) can be used to enhance subgrid-scale organization by forming clusters representative of the convective scales and thus yield a stochastic representation of subgrid-scale variability. The authors study the transfer of energy from the convective to the larger atmospheric scales through nonlinear wave interactions. This is done using a shallow water (SW) model initialized with equatorial wave modes. By letting a CA act on a finer resolution than that of the SW model, it can be expected to mimic the effect of, for instance, gravity wave propagation on convective organization. Employing the CA scheme permits the reproduction of the observed behavior of slowing down equatorial Kelvin modes in convectively active regions, while random perturbations fail to feed back on the large-scale flow. The analysis of kinetic energy spectra demonstrates that the CA subgrid scheme introduces energy backscatter from the smallest model scales to medium scales. However, the amount of energy backscattered depends almost solely on the memory time scale introduced to the subgrid scheme, whereas any variation in spatial scales generated does not influence the energy spectra markedly.
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MIYAUCHI, Toshio, Mamoru TANAHASHI, and Takashi KAKUWA. "Evaluation of Energy Transfer between Grid Scale and Subgrid Scale by Direct Numerical Simulation Data Base." Transactions of the Japan Society of Mechanical Engineers Series B 62, no. 596 (1996): 1406–13. http://dx.doi.org/10.1299/kikaib.62.1406.
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Touber, Emile. "Small-scale two-dimensional turbulence shaped by bulk viscosity." Journal of Fluid Mechanics 875 (July 26, 2019): 974–1003. http://dx.doi.org/10.1017/jfm.2019.531.
Повний текст джерелаАнотація:
Bulk-to-shear viscosity ratios of three orders of magnitude are often reported in carbon dioxide but are always neglected when predicting aerothermal loads in external (Mars exploration) or internal (turbomachinery, heat exchanger) turbulent flows. The recent (and first) numerical investigations of that matter suggest that the solenoidal turbulence kinetic energy is in fact well predicted despite this seemingly arbitrary simplification. The present work argues that such a conclusion may reflect limitations from the choice of configuration rather than provide a definite statement on the robustness of kinetic-energy transfers to the use of Stokes’ hypothesis. Two distinct asymptotic regimes (Euler–Landau and Stokes–Newton) in the eigenmodes of the Navier–Stokes equations are identified. In the Euler–Landau regime, the one captured by earlier studies, acoustic and entropy waves are damped by transport coefficients and the dilatational kinetic energy is dissipated, even more rapidly for high bulk-viscosity fluids and/or forcing frequencies. If the kinetic energy is initially or constantly injected through solenoidal motions, effects on the turbulence kinetic energy remain minor. However, in the Stokes–Newton regime, diffused bulk compressions and advected isothermal compressions are found to prevail and promote small-scale enstrophy via vorticity–dilatation correlations. In the absence of bulk viscosity, the transition to the Stokes–Newton regime occurs within the dissipative scales and is not observed in practice. In contrast, at high bulk viscosities, the Stokes–Newton regime can be made to overlap with the inertial range and disrupt the enstrophy at small scales, which is then dissipated by friction. Thus, flows with substantial inertial ranges and large bulk-to-shear viscosity ratios should experience enhanced transfers to small-scale solenoidal kinetic energy, and therefore faster dissipation rates leading to modifications of the heat-transfer properties. Observing numerically such transfers is still prohibitively expensive, and the present simulations are restricted to two-dimensional turbulence. However, the theory laid here offers useful guidelines to design experimental studies to track the Stokes–Newton regime and associated modifications of the turbulence kinetic energy, which are expected to persist in three-dimensional turbulence.
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Agudelo Rueda, Jeffersson A., Daniel Verscharen, Robert T. Wicks, Christopher J. Owen, Georgios Nicolaou, Kai Germaschewski, Andrew P. Walsh, Ioannis Zouganelis, and Santiago Vargas Domínguez. "Energy Transport during 3D Small-scale Reconnection Driven by Anisotropic Plasma Turbulence." Astrophysical Journal 938, no. 1 (October 1, 2022): 4. http://dx.doi.org/10.3847/1538-4357/ac8667.
Повний текст джерелаАнотація:
Abstract Energy dissipation in collisionless plasmas is a long-standing fundamental physics problem. Although it is well known that magnetic reconnection and turbulence are coupled and transport energy from system-size scales to subproton scales, the details of the energy distribution and energy dissipation channels remain poorly understood. Especially, the energy transfer and transport associated with 3D small-scale reconnection that occurs as a consequence of a turbulent cascade is unknown. We use an explicit fully kinetic particle-in-cell code to simulate 3D small-scale magnetic reconnection events forming in anisotropic and decaying Alfvénic turbulence. We identify a highly dynamic and asymmetric reconnection event that involves two reconnecting flux ropes. We use a two-fluid approach based on the Boltzmann equation to study the spatial energy transfer associated with the reconnection event and compare the power density terms in the two-fluid energy equations with standard energy-based damping, heating, and dissipation proxies. Our findings suggest that the electron bulk flow transports thermal energy density more efficiently than kinetic energy density. Moreover, in our turbulent reconnection event, the energy density transfer is dominated by plasma compression. This is consistent with turbulent current sheets and turbulent reconnection events, but not with laminar reconnection.
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MIYAUCHI, Toshio, Mamoru TANAHASHI, and Takashi KAKUWA. "Evaluation of Energy Transfer between Grid Scale and Subgrid Scale by Use of Direct Numerical Simulation Data Base." JSME International Journal Series B 40, no. 3 (1997): 343–50. http://dx.doi.org/10.1299/jsmeb.40.343.
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Cortese, Barbara, Claudia Piliego, Ilenia Viola, Stefania D’Amone, Roberto Cingolani, and Giuseppe Gigli. "Engineering Transfer of Micro- and Nanometer-Scale Features by Surface Energy Modification." Langmuir 25, no. 12 (June 16, 2009): 7025–31. http://dx.doi.org/10.1021/la900248j.
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Aluie, Hussein, Matthew Hecht, and Geoffrey K. Vallis. "Mapping the Energy Cascade in the North Atlantic Ocean: The Coarse-Graining Approach." Journal of Physical Oceanography 48, no. 2 (February 2018): 225–44. http://dx.doi.org/10.1175/jpo-d-17-0100.1.
Повний текст джерелаАнотація:
AbstractA coarse-graining framework is implemented to analyze nonlinear processes, measure energy transfer rates, and map out the energy pathways from simulated global ocean data. Traditional tools to measure the energy cascade from turbulence theory, such as spectral flux or spectral transfer, rely on the assumption of statistical homogeneity or at least a large separation between the scales of motion and the scales of statistical inhomogeneity. The coarse-graining framework allows for probing the fully nonlinear dynamics simultaneously in scale and in space and is not restricted by those assumptions. This paper describes how the framework can be applied to ocean flows. Energy transfer between scales is not unique because of a gauge freedom. Here, it is argued that a Galilean-invariant subfilter-scale (SFS) flux is a suitable quantity to properly measure energy scale transfer in the ocean. It is shown that the SFS definition can yield answers that are qualitatively different from traditional measures that conflate spatial transport with the scale transfer of energy. The paper presents geographic maps of the energy scale transfer that are both local in space and allow quasi-spectral, or scale-by-scale, dynamics to be diagnosed. Utilizing a strongly eddying simulation of flow in the North Atlantic Ocean, it is found that an upscale energy transfer does not hold everywhere. Indeed certain regions near the Gulf Stream and in the Equatorial Countercurrent have a marked downscale transfer. Nevertheless, on average an upscale transfer is a reasonable mean description of the extratropical energy scale transfer over regions of O(103) km in size.
Дисертації з теми "Scale-by-scale energy transfer"
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Mallangi, Siva Sai Reddy. "Low-Power Policies Based on DVFS for the MUSEIC v2 System-on-Chip." Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-229443.
Повний текст джерелаАнотація:
Multi functional health monitoring wearable devices are quite prominent these days. Usually these devices are battery-operated and consequently are limited by their battery life (from few hours to a few weeks depending on the application). Of late, it was realized that these devices, which are currently being operated at fixed voltage and frequency, are capable of operating at multiple voltages and frequencies. By switching these voltages and frequencies to lower values based upon power requirements, these devices can achieve tremendous benefits in the form of energy savings. Dynamic Voltage and Frequency Scaling (DVFS) techniques have proven to be handy in this situation for an efficient trade-off between energy and timely behavior. Within imec, wearable devices make use of the indigenously developed MUSEIC v2 (Multi Sensor Integrated circuit version 2.0). This system is optimized for efficient and accurate collection, processing, and transfer of data from multiple (health) sensors. MUSEIC v2 has limited means in controlling the voltage and frequency dynamically. In this thesis we explore how traditional DVFS techniques can be applied to the MUSEIC v2. Experiments were conducted to find out the optimum power modes to efficiently operate and also to scale up-down the supply voltage and frequency. Considering the overhead caused when switching voltage and frequency, transition analysis was also done. Real-time and non real-time benchmarks were implemented based on these techniques and their performance results were obtained and analyzed. In this process, several state of the art scheduling algorithms and scaling techniques were reviewed in identifying a suitable technique. Using our proposed scaling technique implementation, we have achieved 86.95% power reduction in average, in contrast to the conventional way of the MUSEIC v2 chip’s processor operating at a fixed voltage and frequency. Techniques that include light sleep and deep sleep mode were also studied and implemented, which tested the system’s capability in accommodating Dynamic Power Management (DPM) techniques that can achieve greater benefits. A novel approach for implementing the deep sleep mechanism was also proposed and found that it can obtain up to 71.54% power savings, when compared to a traditional way of executing deep sleep mode.Nuförtiden så har multifunktionella bärbara hälsoenheter fått en betydande roll. Dessa enheter drivs vanligtvis av batterier och är därför begränsade av batteritiden (från ett par timmar till ett par veckor beroende på tillämpningen). På senaste tiden har det framkommit att dessa enheter som används vid en fast spänning och frekvens kan användas vid flera spänningar och frekvenser. Genom att byta till lägre spänning och frekvens på grund av effektbehov så kan enheterna få enorma fördelar när det kommer till energibesparing. Dynamisk skalning av spänning och frekvens-tekniker (såkallad Dynamic Voltage and Frequency Scaling, DVFS) har visat sig vara användbara i detta sammanhang för en effektiv avvägning mellan energi och beteende. Hos Imec så använder sig bärbara enheter av den internt utvecklade MUSEIC v2 (Multi Sensor Integrated circuit version 2.0). Systemet är optimerat för effektiv och korrekt insamling, bearbetning och överföring av data från flera (hälso) sensorer. MUSEIC v2 har begränsad möjlighet att styra spänningen och frekvensen dynamiskt. I detta examensarbete undersöker vi hur traditionella DVFS-tekniker kan appliceras på MUSEIC v2. Experiment utfördes för att ta reda på de optimala effektlägena och för att effektivt kunna styra och även skala upp matningsspänningen och frekvensen. Eftersom att ”overhead” skapades vid växling av spänning och frekvens gjordes också en övergångsanalys. Realtidsoch icke-realtidskalkyler genomfördes baserat på dessa tekniker och resultaten sammanställdes och analyserades. I denna process granskades flera toppmoderna schemaläggningsalgoritmer och skalningstekniker för att hitta en lämplig teknik. Genom att använda vår föreslagna skalningsteknikimplementering har vi uppnått 86,95% effektreduktion i jämförelse med det konventionella sättet att MUSEIC v2-chipets processor arbetar med en fast spänning och frekvens. Tekniker som inkluderar lätt sömn och djupt sömnläge studerades och implementerades, vilket testade systemets förmåga att tillgodose DPM-tekniker (Dynamic Power Management) som kan uppnå ännu större fördelar. En ny metod för att genomföra den djupa sömnmekanismen föreslogs också och enligt erhållna resultat så kan den ge upp till 71,54% lägre energiförbrukning jämfört med det traditionella sättet att implementera djupt sömnläge.
Книги з теми "Scale-by-scale energy transfer"
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Krishnamurti, T. N., H. S. Bedi, and V. M. Hardiker. An Introduction to Global Spectral Modeling. Oxford University Press, 1998. http://dx.doi.org/10.1093/oso/9780195094732.001.0001.
Повний текст джерелаАнотація:
This book is an indispensable guide to the methods used by nearly all major weather forecast centers in the United States, England, Japan, India, France, and Australia. Designed for senior-level undergraduates and first-year graduate students, the book provides an introduction to global spectral modeling. It begins with an introduction to elementary finite-difference methods and moves on towards the gradual description of sophisticated dynamical and physical models in spherical coordinates. Topics include computational aspects of the spectral transform method, the planetary boundary layer physics, the physics of precipitation processes in large-scale models, the radiative transfer including effects of diagnostic clouds and diurnal cycle, the surface energy balance over land and ocean, and the treatment of mountains. The discussion of model initialization includes the treatment of normal modes and physical processes, and the concluding chapter covers the spectral energetics as a diagnostic tool for model evaluation.
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Zeitlin, Vladimir. Resonant Wave Interactions and Resonant Excitation of Wave-guide Modes. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198804338.003.0012.
Повний текст джерелаАнотація:
The idea of resonant nonlinear interactions of waves, and of resonant wave triads, is first explained using the example of Rossby waves, and then used to highlight a mechanism of excitation of wave-guide modes, by impinging free waves at the oceanic shelf, and at the equator. Physics and mathematics of the mechanism, which is related to the phenomena of parametric resonance and wave modulation, are explained in detail in both cases. The resulting modulation equations, of Ginzburg–Landau or nonlinear Schrodinger type, are obtained by multi-scale asymptotic expansions and elimination of resonances, after the explanation of this technique. The chapter thus makes a link between geophysical fluid dynamics and other branches of nonlinear physics. A variety of nonlinear phenomena including coherent structure formation is displayed. The resonant excitation of wave-guide modes provides an efficient mechanism of energy transfer to the wave guides from the large to the small.
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Griffith-Jones, Stephany, María Luz Martínez Sola, and Javiera Petersen Muga. The Role of CORFO in Chile’s Development. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198827948.003.0006.
Повний текст джерелаАнотація:
CORFO was one of the first national development banks in Latin America, and played a decisive role in Chile’s national development strategy. In recent decades, its relative scale has diminished significantly. Its financial support currently represents only 1% of Chile’s GDP and has switched from giving credit directly to becoming a second-tier institution whose main instruments are not loans but guarantees. Its support for strategic sectors has been decisive to incentivize innovative, value-added activities, such as the Start-Up programme or renewable energy projects. Nonetheless, its limited scale severely reduces its potential ability to transform Chile’s economy or deploy a countercyclical role in a crisis scenario. This study suggests that CORFO could take advantage of Chile’s mature capital market, by raising additional funds through bond issues.
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Bang, Peter Fibiger, C. A. Bayly, and Walter Scheidel, eds. The Oxford World History of Empire. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780199772360.001.0001.
Повний текст джерелаАнотація:
The Oxford World History of Empire, Vol.1: The Imperial Experience is dedicated to synthesis and comparison. Following a comprehensive theoretical survey and world-historical synthesis, fifteen chapters analyze and explore the multifaceted experience of empire across cultures and through five millennia. The broad range of perspectives includes: scale, world systems and geopolitics, military organization, political economy and elite formation, monumental display, law, mapping and registering, religion, literature, the politics of difference, resistance, energy transfers, ecology, memories, and the decline of empires. This broad set of topics is united by the central theme of power, examined under four headings: systems of power, cultures of power, disparities of power, and memory and decline. Taken together, these chapters offer a comprehensive view of the imperial experience in world history
Частини книг з теми "Scale-by-scale energy transfer"
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Nishimura, Takahiro. "Fluorescence Energy Transfer Computing." In Photonic Neural Networks with Spatiotemporal Dynamics, 51–70. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-5072-0_3.
Повний текст джерелаАнотація:
AbstractThis chapter presents the concept and implementation of fluorescence energy transfer computing, specifically utilizing Förster resonance energy transfer (FRET) between molecular fluorophores and quantum dots. FRET is a non-radiative form of excitation energy transfer that depends on the configuration and optical properties of molecular fluorophores and quantum dots. By designing energy flows through FRET, signal processing can be implemented to perform desired operations. Because the phenomenon occurs at the nanometer scale, miniaturization of information devices can be expected. This chapter reviews the concepts of FRET computing and the implementation of FRET computing devices. Then, a framework of DNA scaffold logic, which systematically handles FRET-based logic operations, is described. Finally, the idea of a FRET network is discussed as a method for enhancing FRET computing performance.
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Zhou, Li-bin, Yan Du, Zhuo Feng, Tao Cui, Xia Chen, Shan-wei Luo, Yu-ze Chen, et al. "Comparative study of mutations induced by carbon-ion beams and gamma-ray irradiations in Arabidopsis thaliana at the genome-wide scale." In Mutation breeding, genetic diversity and crop adaptation to climate change, 451–58. Wallingford: CABI, 2021. http://dx.doi.org/10.1079/9781789249095.0046.
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Abstract Mutation breeding induced by irradiation with highly energetic photons and ion beams is one of the important methods to improve plant varieties, but the mutagenic effects and molecular mechanisms are often not entirely clear. Traditional research is focused on phenotype screening, chromosome aberration tests and genetic variation analysis of specific genes. The whole genome sequencing technique provides a new method to understand and undertake the comprehensive identification of mutations caused by irradiations with different linear energy transfer (LET). In this study, ten Arabidopsis thaliana M3 lines induced by carbon-ion beams (CIB) and ten M3 lines induced by gamma-rays were re-sequenced by using the Illumina HiSeq sequencing platform, and the single base substitutions (SBSs) and small insertions or deletions (indels) were analysed comparatively. It was found that the ratio of SBSs to small indels for M3 lines induced by CIB was 2.57:1, whereas the ratio was 1.78:1 for gamma-rays. The ratios of deletions to insertions for carbon ions and gamma-rays were 4.8:1 and 2.8:1, respectively. The single-base indels were more prevalent than those equal to or greater than 2 bp in both CIB and gamma-ray induced M3 lines. Among the detected SBSs, the ratio of transitions to transversions induced by carbon-ion irradiation was 1.01 and 1.42 for gamma-rays; these values differ greatly from the 2.41 reported for spontaneous substitutions. This study provides novel data on molecular characteristics of CIB and gamma-ray induced mutations at the genome-wide scale. It can also provide valuable clues for explaining the potential mechanism of plant mutation breeding by irradiations with different LETs.
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Daglio, Laura. "The Urban Potential of Multifamily Housing Renovation." In The Urban Book Series, 627–37. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-29515-7_56.
Повний текст джерелаАнотація:
AbstractMultifamily post-war middle-class housing in Italy represents a significant heritage which strongly characterizes urban landscapes. Although this huge stock has long been addressed by national policies as a major potential to pursue European climate targets, only the recent massive incentive measures (Superbonus 110%) have started to produce results for the energy upgrading of the buildings, offering alternatives and motivations (through the size of the public funding and the institution of the credit transfer) to the issues of the typical ownership fragmentation. However, these first partial outcomes are controversial from a life cycle, a social and an economic point of view. In addition, policies focus only on the energy performance of the single building, conceiving the interventions through a narrow-minded and generic attitude. The typological obsolescence and the multifaceted relationships between the building and the neighborhood are neglected, although important social, economic and energy efficiency benefits might emerge when addressing the renovation through a multi-scalar, multifunctional, and place-based approach. Stemming from the collection and analysis of ongoing initiatives and projects, possible models are outlined, enlarging the scenario of the transformations to include the urban scale. For example, underused private spaces can host new public or semi-public functions to contribute on the one hand to the management costs of the condominium and on the other hand to trigger local neighborhood regenerations. Moreover, widening the transformation perspective can envisage a group of buildings and the adjacent public spaces as a system to create energy districts where energy infrastructures introduce new amenities and added value.
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Fragkos, Panagiotis, Eleni Kanellou, George Konstantopoulos, Alexandros Nikas, Kostas Fragkiadakis, Faidra Filipidou, Theofano Fotiou, and Haris Doukas. "Energy Poverty and Just Transformation in Greece." In Studies in Energy, Resource and Environmental Economics, 235–67. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-35684-1_10.
Повний текст джерелаАнотація:
AbstractLow-income population groups often face high energy poverty risks. This phenomenon can be exacerbated through the implementation of ambitious environmental policies to achieve the energy transition—said policies, such as the application of additional taxes on energy products, may lead to regressive social and distributional impacts on low-income households thus increasing the risk of energy poverty. This study focusses on Greece and combines a qualitative analysis of the EU and Greek policy context and strategic framework for energy poverty as well as related poverty alleviation measures with a state-of-the-art model-based assessment of the equity and distributional impacts of the net-zero transition in the country. We use the GEM-E3-FIT general equilibrium model, expanded to represent ten income classes differentiated by income sources, saving rates and consumption patterns. The new modelling capabilities of GEM-E3-FIT are applied to quantify the distributional impacts of ambitious emission reduction targets and at the same time explore their effects on energy-related expenditure and energy poverty by income class in Greece. The country’s transition to climate neutrality increases modestly the income inequality across income classes, with low-income households facing the most negative effects. However, using carbon tax revenues as lump-sum transfers to support household income and as reduced social security contributions have the potential to boost employment and scale down income inequality in Greece.
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De Martino, Paolo. "Towards Circular Port–City Territories." In Regenerative Territories, 161–71. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-78536-9_10.
Повний текст джерелаАнотація:
AbstractPort and city authorities all over Europe and beyond are striving with finding solutions able to combine sustainability with economic growth. Several global urgencies in fact, such as climate change, energy transition, the exponential changes in the scale of ports and ships and last but not least the economic and health shock related to the coronavirus pandemic, are challenging the spaces where ports physically meet their cities, generating processes of caesura within the urban patterns with consequent impacts on the quality of life. In port cities, infrastructures and energy flows overlap with city flows and patterns that change with different rhythms and temporalities. This discrepancy creates abandonment and marginality between port and city. This today is no longer sustainable. New approaches and solutions that look at integration and circularity rather than separation are necessary.Circularity has been widely discussed in the literature. However, the concept still remains very controversial, especially when it comes to port cities where new definitions are needed in particular to better understand the spatial dimension of circularity. The Rotterdam therefore case study stands exemplary. Here, the concept of the circular economy refers mostly to the theme of obsolete industrial buildings and marginal that are reinserted again within the urban metabolism. The case of Rotterdam points out that the competition of the port today goes through the quality of its relationship spaces and the ability of the different actors involved in the planning process to hold together economic growth and environmental sustainability. The areas along the river are in fact the most fascinating places in the city and today they are ready for a different use. In order for the city to become an attractive place to live it is necessary to build new, innovative and sustainable spatial visions. This will lead to scenarios of sustainable coexistence between port and city. Therefore, these two agendas (sustainable port and city attractiveness) came together in the area known as Makers district (M4H) which, together with RDM campus, represents the Rotterdam testing ground for innovation.Therefore, this chapter, by arguing that ports will play a crucial role in the transition towards more circularity investigates how to make it happen and how to transform the challenges of the port into opportunities for a territorial regeneration towards new forms of integration. In order to answer the question, the case of Rotterdam is presented to analyse a model of urban regeneration where different planning agencies—mainly port authority, municipality, universities and private parties—work together at different scales to define a sustainable coexistence of interests. The research, which draws data on existing literature and policy documents analysis, firstly introduces the spatial and governance structures of the city of Rotterdam as part of a bigger metropolitan region. Secondly, it analyses the case of “Stadshavens strategy” as an emblematic example to overcome conflicts and path dependencies at the intersection of land and water. Finally, it concludes by highlighting some limitations and path dependencies that could make the transition to new forms of the circular economy very difficult in the future.
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Sudarmadji, Sudarmadji, Sugeng Hadi Susilo, and Asrori Asrori. "The Combined Method to Improve Heat Transfer Coefficient on Heat Exchanger." In Heat Transfer [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.105880.
Повний текст джерелаАнотація:
The heat transfer process occurs all the time around us, from simple household appliances to equipment used in large industries. Energy efficiency in large-scale use in industry is necessary because it is related to company profits. One way to save energy use in heat exchangers is to change the thermal properties of the cooling fluid. The addition of particles of the nanometer size (nanofluids) in the working fluid will improve the performance of the heat exchanger, and the main goal is the highest efficiency. In addition, there is another method to increase the heat transfer rate, namely, by vibrating the cooling fluid. This chapter will discuss combining nanofluids and ultrasonic vibrations in heat transfer processes in heat exchangers. The application of these two methods simultaneously gives rise to several advantages to the heat transfer system, will promote higher heat transfer, and at the same time function as cleaning of scale/deposits that often appear on the surface of the heat exchanger.
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Dehra, Himanshu. "Developments in Wireless Power Transfer Using Solar Energy." In Wireless Power Transfer – Recent Development, Applications and New Perspectives. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.97099.
Повний текст джерелаАнотація:
This chapter presents state-of-the-art and major developments in wireless power transfer using solar energy. The brief state-of-the-art is presented for solar photovoltaic technologies which can be combined with wireless power transfer (WPT) to interact with the ambient solar energy. The main purpose of the solar photovoltaic system is to distribute the collected electrical energy in various small-scale power applications wirelessly. These recent developments give technology based on how to transmit electrical power without any wires, with a small-scale by using solar energy. The power can also be transferred wirelessly through an inductive coupling as an antenna. With this wireless electricity we can charge and make wireless electricity as an input source to electronic equipment such as cellphone, MP3 Player etc. In harvesting energy, technologies of ambient solar radiation like solar photovoltaic, kinetic, thermal or electro-magnetic (EM) energy can be used to recharge the batteries. Radio frequency (RF) harvesting technologies are also popular as they are enormously available in the atmosphere. The energy converted to useful DC energy which can be used to charge electrical devices which need low power consumption. The chapter has also presented a parallel plate photovoltaic amplifier connected to a potentiometer as a Resistance-Capacitance (RC) circuit power amplifier. The effect of inductance and resulting power transfer has been theoretically determined in the RC amplifier circuit. The electrical and thermal properties and measurements from a parallel plate photovoltaic amplifier were collected to analyze the unbalanced power transfer and inductance in a nonlinear RC circuit amplifier using equivalent transfer functions. The concept of Wireless Information and Power Transfer using Electromagnetic and Radio Waves of Solar Energy Spectrum is also briefly outlined.
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Rosa Oliveira Panão, Miguel. "Evolutionary Design of Heat Exchangers in Thermal Energy Storage." In Heat Transfer - Design, Experimentation and Applications [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.96300.
Повний текст джерелаАнотація:
The efficiency and ability to control the energy exchanges in thermal energy storage systems using the sensible and latent heat thermodynamic processes depends on the best configuration in the heat exchanger’s design. In 1996, Adrian Bejan introduced the Constructal Theory, which design tools have since been explored to predict the evolution of the architecture in flow systems. This chapter reviews the fundamental knowledge developed by the application of the constructal principle to the energy flows in the design of heat exchangers of thermal energy storage systems. It introduces the Svelteness and scale analysis, as two constructal tools in the evolutionary design of engineering flow systems. It also includes the analysis on essential scales of several configurations, or energy flow architectures, toward establishing the main guidelines in the design of heat exchangers for storing thermal energy.
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M., Balamurugan, Raghu N., Kamala N., Trupti V. Nandikolmath, and Sarat Kumar Sahoo. "Solar Powered Electric Vehicle Through Wireless Power Transfer." In Electric Vehicles and the Future of Energy Efficient Transportation, 219–42. IGI Global, 2021. http://dx.doi.org/10.4018/978-1-7998-7626-7.ch009.
Повний текст джерелаАнотація:
Solar powered wireless electric vehicle charging technology functions independently without interface with the utility grid. Wireless power transfer (WPT) technology is incorporated for wireless charging, which brings the benefits of safe operation, less pollution, and little maintenance cost. WPT technology necessitates no physical connection between the charging device and vehicle, thus hazards and inconvenience produced by conventional charging methods have been minimized. WPT in electric vehicle can be used to reduce the charging time, range, and cost. In this chapter, the various configurations of WPT like inductive, capacitive, resonant, and roadway power transfer techniques have been presented. The small-scale prototype of wireless charging has been developed in the laboratory by incorporating inductive power transfer technique. The experimental results have been presented to validate the feasibility of the system in real time.
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Das, Hirakh Jyoti, Pinakeswar Mahanta, and Rituraj Saikia. "A Future Trend on Research Scope of Numerical Simulation on Conical Fluidized Bed." In Handbook of Research on Developments and Trends in Industrial and Materials Engineering, 401–37. IGI Global, 2020. http://dx.doi.org/10.4018/978-1-7998-1831-1.ch017.
Повний текст джерелаАнотація:
Fluidized bed technology is a well-established environment friendly technology, by which energy can be generated through combustion and gasification techniques. It is widely prevalent today owing to its excellent heat transfer, mixing characteristics and compactness. The design and scale-up of the fluidized beds are vital to the enhancement of heat transfer and mixing characteristics. However, heat transfer characteristics play a key role in determining the combustion and gasification characteristics. CFD is a technique which helps to optimize the design and operation of fluidized bed combustor and gasifiers. Enhancement of computing speed and numerical techniques has led to CFD being used as a widely implemented tool to provide a bridge between laboratory scale and industrial study. In this chapter, a comprehensive review of CFD modelling and experimental study on the conical fluidized bed has been carried out. Primarily this chapter demonstrates probable future accomplishments and identifies trends and regions where further research is required.
Тези доповідей конференцій з теми "Scale-by-scale energy transfer"
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Abouricha, N., M. EL Alami, and K. Souhar. "Numerical study of heat transfer by natural convection in a large-scale cavity heated from below." In 2016 International Renewable and Sustainable Energy Conference (IRSEC). IEEE, 2016. http://dx.doi.org/10.1109/irsec.2016.7984031.
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Dang, Zhigang, Yang Zhou, Yuetao Shi, Chaoqun Ma, and Ming Gao. "NUMERICAL STUDY OF THERMAL PERFORMANCE FOR LARGE-SCALE WET COOLING TOWER EQUIPPED WITH A FAN DRIVEN BY WATER DROPPING POTENTIAL ENERGY." In International Heat Transfer Conference 16. Connecticut: Begellhouse, 2018. http://dx.doi.org/10.1615/ihtc16.cov.023243.
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Guillard, Tony, Gilles Flamant, Daniel Laplaze, Jean-François Robert, Bruno Rivoire, and Joseph Giral. "Towards the Large Scale Production of Fullerenes and Nanotubes by Solar Energy." In ASME 2001 Solar Engineering: International Solar Energy Conference (FORUM 2001: Solar Energy — The Power to Choose). American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/sed2001-165.
Повний текст джерелаАнотація:
Abstract Conventional methods for the synthesis of fullerenes and carbon nanotubes such as laser or electric arc ablation have failed when the process is scaled up. Our ultimate goal is to scale a solar process up from 2 to 500 kW; this paper shows that our method for achieving this scale up is valid because we were able to predict process performance variables at the 50 kW level from preliminary experimental results from 2 kW experiments. The key parameters that characterize this process are the carbon soot mass flow rate and the desired product yield. The carbon soot production rate is a function of the target temperature and this can be predicted in a straightforward way from a heat transfer model of the larger system. The yield is a more complicated function of specific reactor variables such as patterns of fluid flow, residence times at various temperatures and the reaction chemistry, but we have found that for fullerenes it depends primarily on the concentration of carbon vapor in the carrier gas, the target temperature and the temperature distribution in the cooling zone. Using these parameters, we scaled our process up to 50 kW and compared the predicted results to the measured performance. A graphite target 6 cm in diameter was vaporized in an argon atmosphere and a reduced pressure of 120–240 hPa with a solar flux density in the range 600–900 W/cm2. Vaporization rates of 20 g/h were measured with a fullerene production rate equal to or greater than 1 g/h, i.e. the expected results.
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Si, Xiuhua, Jinxiang Xi, and Xihai Tao. "The Study of Calcium Carbonate Scaling on Low Energy Surfaces." In 2010 14th International Heat Transfer Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/ihtc14-22058.
Повний текст джерелаАнотація:
Scale deposition on heat transfer surfaces from water containing dissolved salts reduces the efficiency and performance of heat transfer equipments considerably. Scale deposition could be reduced through physical or chemical methods. In some cases, chemical methods are unacceptable, due to cost, contamination issues, etc. In these cases, physical methods are the only acceptable choices. Surface energy of the heat exchanger has been thought to be one important factor affecting the growth of fouling. Applying low energy surfaces to reduce scaling deposition is one of the effective physical methods. The formation and the characteristics of the calcium carbonate scaling on low energy surfaces have been studied in this paper. Copper and stainless steel surfaces were modified by micro-scale (μm thickness) PTFE (Poly-Tetrofluorethylene) films and nano-scale (nm thickness) thiolate SAMs (Self-Assembly Monolayers). The resulting surface energy of PTFE films and SAMs layers based on copper and stainless steel were significantly reduced compared with the original metal surfaces. To study the formation of the calcium carbonate scale, a recirculation cooling water system was used. The formation of the calcium carbonate scale on PTFE surfaces, SAMs surfaces, polished copper surfaces, and polished stainless steel surfaces were investigated respectively. The rate of calcium carbonate scale formation was decreased and the induction period was prolonged with the decrease of the heat transfer surface energy. The characteristics of the calcium carbonate scale formed on heat transfer surfaces with different surface energies was analyzed with fractal theory after taking photos with SEM (Scanning Electron Microscope). The fractal dimension values of the calcium carbonate scale on different heat transfer surfaces with different surface energies were calculated. The results showed that the fractal dimension values of calcium carbonate scale formed on lower energy PTFE and Cu-SAMs surfaces were greater than those that formed on higher energy Cu and stainless steel surfaces. Results of this study clearly indicated that the formation of calcium carbonate scaling on lower energy heat transfer surfaces is reduced.
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Comly, Renee, and Alex Mathew. "A Small-Scale Solution for a Big Energy Problem: Renewable Distributed Energy." In ASME 2009 3rd International Conference on Energy Sustainability collocated with the Heat Transfer and InterPACK09 Conferences. ASMEDC, 2009. http://dx.doi.org/10.1115/es2009-90355.
Повний текст джерелаАнотація:
A Small-Scale Solution for a Big Energy Problem: Renewable Distributed Energy. Locally generated biomass, industrial and municipal wastes, coal and plastics have a significant part to play in providing a source of reliable and economic energy in the US. The ability to use these materials reliably and cleanly can be addressed with small-scale gasification technology to provide distributed generation. A technology that has improved on the historical success of gasification to provide these elements is TURNW2E™ Gasification. This technology is specifically designed to convert locally available energy resources into a clean fuel gas which is then subsequently used for heat and or power generation. This technology has the ability to operate cleanly and interchangeably using waste materials and /or coal. With the ability to produce power economically from 100 kW to 5 MW it can provide distributed generation at institutions, DOD facilities, and industrial complexes. This creates a reliable and economical energy source for the user, while disposing of wastes in an environmentally sound manner. This replaces landfill use with the energy transformation process of gasification, which provides enormous environmental benefits, including the elimination of carcinogens and reduction of greenhouse gas emissions caused by incineration processes. The use of renewable biomass and wastes provides a sustainable source of electricity that is unrestricted by grid access, providing tremendous potential to reduce US fuel imports. Using this approach, the user can create jobs and power in a sustainable scenario; without sending precious energy dollars overseas, using this process in a distributed manner will help strengthen our nation’s economy, and provide improvements to the quality of life wherever it is installed. By having the ability to use many different feedstocks, the technology can enable the avoidance of landfilling MSW and industrial wastes, including tires; it can use waste wood such as railroad ties, beetle-infested pine, and forestry wastes, farm wastes and natural disaster debris to generate renewable energy for local use or sale to the grid. Materials for processing are varied, and thus, the technology flexibility enables small-scale use in a wide range of installations, a landfill site, transfer station, farm, hospital, manufacturing facility, resort, DOD base, island community, university, and local municipal site. TURNW2E™ Gasification is available at commercial scale and is currently installed at two facilities overseas, with three US facilities planned for ’09. A training and continuing education /R&D facility is underway in the US.
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Fujiwara, Yasufumi, Kazuhiko Nakamura, Shouichi Takemoto, Jun-ichi Sugino, Yoshikazu Terai, Masato Suzuki, and Masayoshi Tonouchi. "Direct Observation of Picosecond-Scale Energy-Transfer Processes in Er,O-Codoped GaAs by Pump-Probe Reflection Technique." In PHYSICS OF SEMICONDUCTORS: 28th International Conference on the Physics of Semiconductors - ICPS 2006. AIP, 2007. http://dx.doi.org/10.1063/1.2729860.
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Zhou, Shaodong, and Zhizhong Wang. "Industry location adjustment and industry transfer in China caused by large scale non-grid-connected wind power industrial systems." In 2010 World Non-Grid-Connected Wind Power and Energy Conference (WNWEC). IEEE, 2010. http://dx.doi.org/10.1109/wnwec.2010.5673565.
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Hisakuni, Yousuke, Akira Kano, Hideaki Uehara, Tomoko Monda, Junko Hirokawa, Osamu Nishimura, Kenji Hirohata, Toshinobu Ito, Shohei Takami, and Kiyokazu Sato. "Stress Concentration Mechanism in Superconducting Coil Quench Phenomenon by Large-Scale Finite Element Analysis." In ASME 2022 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/imece2022-94914.
Повний текст джерелаАнотація:
Abstract A quench is the transition from a superconducting state to a normal conducting state. Elucidating the mechanism of quenching caused by mechanical disturbances (training quench) requires a detailed understanding of the stress state in the coil during excitation. In this study, we developed a large-scale analysis method that can precisely analyze where strain energy is concentrated and loss energy is generated due to thermal stress and electromagnetic force in superconducting coils by considering the detailed structure of superconducting wires and the wire alignment disorder caused by constraints during winding. The results showed that strain energy in the resin is concentrated in the region of overlap between the strain energy distribution caused by the macroscopic deformation of the coil and the geometrically inhomogeneous region, including the wire transfer zone. Furthermore, comparative verification using acoustic emission measurements to determine damage locations suggests that quench is also concentrated at the transfer zone in the actual coil, thus demonstrating the validity of the analysis. A sub-model of the area around the transfer zone, which was found in the large-scale analysis, was created, and crack propagation analysis was conducted using the phase-field method. Crack propagation in the resin and increased deformation of the wire due to weakening of the supporting rigidity of the wire caused by the crack propagation were observed.
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Chen, Jun, Joseph Katz, and Charles Meneveau. "Study of Scale-Interactions in Strained and Destrained Turbulence." In ASME 2004 Heat Transfer/Fluids Engineering Summer Conference. ASMEDC, 2004. http://dx.doi.org/10.1115/ht-fed2004-56402.
Повний текст джерелаАнотація:
This paper examines the interactions among different length-scales of turbulence during straining and de-straining of the flow. Understanding scale-interactions is a crucial ingredient in formulating improved subgrid models for Large Eddy Simulations. In this experimental study, planar Particle Image Velocimetry (PIV) measurements are performed in a water tank, in which high Reynolds number turbulence with very low mean velocity is generated by an array of spinning grids. Planar straining and de-straining are applied by pushing or pulling rectangular piston whose width is equal to that of the a rectangular tank towards and away from the bottom. The velocity of the piston is computer controlled and synchronized with the PIV system. The initial background turbulence, characterized by the distributions of rms values and energy spectra, confirms that that the turbulence is nearly isotropic and homogeneous. The applied straining is characterized using high-speed photography of the piston and by PIV measurements of the mean flow. The results consist of the time evolution of several turbulence parameters subjected to a sequence of straining and destraining motions, with particular emphasis on the Reynolds stresses, Sub-grid scale (SGS) stresses, SGS anisotropy and SGS dissipation. The paper also examines the scale dependence of the SGS stress and dissipation, and compares the energy flux between different scales during the straining and destraining parts of the deformation.
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Si, Xiuhua, Sungmin Youn, and Jinxiang Xi. "Reducing Scale Deposition by Surface Modification and Magnetic Water Treatment." In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-12796.
Повний текст джерелаАнотація:
Scale deposition (or fouling) on metal surfaces from salt-containing water considerably reduces the efficiency and performance of heat transfer equipments. In industrial practices, scale deposition could be reduced through physical or chemical methods. However, in some cases chemical methods are unpractical due to cost and contamination issues, rendering the physical methods the only feasible options. The objective of this study was to evaluate the effectiveness of two physical treatments in reducing scale depositions. One is to decrease the surface energy of the heat exchanger wall through surface modification; the other one is to change the crystallography of the small solid particles formed in the solution by applying a magnetic field. For the first method, the scale deposition on PTFE surfaces, SAMs (self-assembly monolayers) surfaces, polished copper surfaces, and polished stainless steel surfaces are investigated respectively. Copper and stainless steel surfaces were modified by micro-scale (μm thickness) PTFE (Poly-Tetrofluorethylene) films and nano-scale (nm thickness) thiolate SAMs. The surface energy of PTFE films and SAMs layers based on copper and stainless steel were significantly reduced compared with the untreated metal surfaces. To study the magnetic treatment effect on the formation of the calcium carbonate scale, a magnetic field up to 0.6 T was implemented in a simulated recirculation cooling water system. A large number of experiments were performed to study the effects of fluid velocity, heat flux, and the bulk concentration of the solution on the fouling rate and induction period of calcium carbonate on various modified surfaces. The experiments showed that the formation rate of the calcium carbonate scale was decreased on modified surfaces and the induction period was prolonged with the decrease of the surface energy. The study also showed that the nucleation and nucleate growth of calcium carbonate particles were enhanced through magnetic water treatment. In addition, using a higher flow rate and/or filtration of suspended calcium carbonate particles achieves a longer induction period.
Звіти організацій з теми "Scale-by-scale energy transfer"
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Duma, Daniel, and Miquel Muñoz Cabré. Risk mitigation and transfer for renewable energy investments: a conceptual review. Stockholm Environment Institute, September 2023. http://dx.doi.org/10.51414/sei2023.042.
Повний текст джерелаАнотація:
The trillions of dollars needed to achieve global climate goals are more than an abstract number. They need to be channeled through viable projects that result in desirable outcomes, such as renewable energy infrastructure in developing countries. The complexity and barriers faced in the project development and finance process are often underestimated. The perception of risk is an important barrier to private investment in developing countries, hence one of the most relevant interventions is to reduce or transfer risk faced by investors. Renewable energy has benefited from this approach, yet its progress has been slow in some regions, such as Sub-Saharan Africa (SSA). In this paper, we look at risk-related interventions in renewable energy investments, particularly from the perspective of developers. To do that, we first review the literature and concepts related to the role of risk, the cost of capital, the project development process, and the investment selection process. The paper further explores the types and relevance of risks faced by renewable energy investors. Finally, the paper examines the use of risk mitigation and transfer (RMT) instruments in private utility-scale renewable energy investments and presents evidence of the effectiveness of RMT in practice.
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Hammouti, A., S. Larmagnat, C. Rivard, and D. Pham Van Bang. Use of CT-scan images to build geomaterial 3D pore network representation in preparation for numerical simulations of fluid flow and heat transfer, Quebec. Natural Resources Canada/CMSS/Information Management, 2023. http://dx.doi.org/10.4095/331502.
Повний текст джерелаАнотація:
Non-intrusive techniques such as medical CT-Scan or micro-CT allow the definition of 3D connected pore networks in porous materials, such as sedimentary rocks or concrete. The definition of these networks is a key step towards the evaluation of fluid flow and heat transfer in energy resource (e.g., hydrocarbon and geothermal reservoirs) and CO2 sequestration research projects. As material heterogeneities play a role at all scales (from micro- to project-scale), numerical models represent a powerful tool for bridging the gap between small-scale measurements provided by X-ray imaging techniques and larger-scale transport properties. This study uses pre-existing medical CT-scan datasets of reference material, namely glass beads and conventional reservoir rocks (Berea sandstone, Boise sandstone, Indiana limestone) to extract the 3D geometry of connected pores using an open-source software (Spam). Pore networks from rock samples were generated from dry and then saturated samples. Binarized datasets were produced for these materials (generated by a thresholding technique) to obtain pore size distribution and tortuosity, as well as preferential paths for fluid flow. Average porosities were also calculated for comparison with those obtained by conventional commercial laboratory techniques. The results obtained show that this approach works well for medium and coarse-grained materials that do not contain a large percentage of fine particles. However, this approach does not allow representative networks to be obtained for fine-grained rocks, due to the fact that small pores (or pore throats) cannot be taken into account in the datasets obtained from the medical CT-Scan. A next step, using datasets produced from a micro- CT scan, is planned in order to be able to generate representative networks in this type of material as well.
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AN ANALYTICAL METHOD FOR EVALUATING THE DEFLECTION AND LOAD-BEARING AND ENERGY ABSORPTION CAPACITY OF ROCKFALL RING NETS CONSIDERING MULTIFACTOR INFLUENCE. The Hong Kong Institute of Steel Construction, September 2022. http://dx.doi.org/10.18057/ijasc.2022.18.3.1.
Повний текст джерелаАнотація:
In this study, an analytical method for evaluating the structural performance, including maximum deflection, load-bearing, and energy absorption capacity of a steel wire-ring net, was proposed to effectively design the ring net of the flexible barrier systems. Puncture tests of the ring nets and two-point traction tests of the three-ring chains with various wire-ring specifications were conducted. Correlation analysis was used to test the results between ring nets and chains, revealing that three structural performance indicators of the test specimens were strongly related. The ring net’s structural performance was affected specifically by ring chains on the shortest load transfer path. Accordingly, a three-ring chain with a flexible boundary corresponded to a fibre–spring element. A three-dimensional analytical model of the ring net was established. Explicit formulas for computing the three indicators of the ring net were derived. Comprehensive quasi-static and impact tests, using different shapes and sizes of punching devices, were conducted, providing valuable data to calibrate and validate this analytical method. The ability of the model in yielding consistent results when implemented at the structure scale was then assessed, based on the data of full-scale impact tests on a 1500kJ-energy rockfall barrier. Lastly, the effects of various factors, such as single ring geometry, the length–width ratio of the net, loading area size, boundary stiffness, and load rate, influencing the structural performance indicators of the ring net were investigated, respectively.