Relevant bibliographies by topics / Scalar driven diffusion

Contents

  1. Journal articles
  2. Dissertations / Theses
  3. Book chapters
  4. Conference papers

Academic literature on the topic 'Scalar driven diffusion'

Author: Grafiati
Published: 4 June 2021
Last updated: 9 February 2022

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles

Select a source type:

Consult the lists of relevant articles, books, theses, conference reports, and other scholarly sources on the topic 'Scalar driven diffusion.'

Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.

You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.

Journal articles on the topic "Scalar driven diffusion"

1

Yeung, P. K. "Multi-scalar triadic interactions in differential diffusion with and without mean scalar gradients." Journal of Fluid Mechanics 321 (August 25, 1996): 235–78. http://dx.doi.org/10.1017/s0022112096007719.

Full text
Abstract:
The spectral mechanisms of the differential diffusion of pairs of passive scalars with different molecular diffusivities are studied in stationary isotropic turbulence, using direct numerical simulation data at Taylor-scale Reynolds number up to 160 on 1283 and 2563 grids. Of greatest interest are the roles of nonlinear triadic interactions between different scale ranges of the velocity and scalar fields in the evolution of spectral coherency between the scalars, and the effects of mean scalar gradients.Analysis of single-scalar spectral transfer (extending the results of a previous study) indicates a robust local forward cascade behaviour at high wavenumbers, which is strengthened by both high diffusivity and mean gradients. This cascade is driven primarily by moderately non-local interactions in which two small-scale scalar modes are coupled via a lower-wavenumber velocity mode near the peak of the energy dissipation spectrum. This forward cascade is coherent, tending to increase the coherency between different scalars at high wavenumbers but to decrease it at lower wavenumbers. However, at early times coherency evolution at high wavenumbers is dominated by de-correlating effects due to a different type of non-local triad consisting of two scalar modes with a moderate scale separation and a relatively high-wavenumber velocity mode. Consequently, although the small-scale motions play little role in spectral transfer, they are responsible for the rapid de-correlation observed at early times. At later times both types of competing triadic interactions become important over a wider wavenumber range, with increased relative strength of the coherent cascade, so that the coherency becomes slow-changing. When uniform mean scalar gradients are present, a stationary state develops in the coherency spectrum as a result of a balance between a coherent mean gradient contribution (felt within about 1 eddy-turnover time) and the net contribution from scale interactions. The latter is made less de-correlating because of a strengthened coherent forward cascade, which is in turn caused by uniform mean gradients acting as a primarily low-wavenumber source of scalar fluctuations with the same spectral content as the velocity field.
APA, Harvard, Vancouver, ISO, and other styles
2

van Sommeren, Daan D. J. A., C. P. Caulfield, and Andrew W. Woods. "Spatially varying mixing of a passive scalar in a buoyancy-driven turbulent flow." Journal of Fluid Mechanics 742 (February 24, 2014): 701–19. http://dx.doi.org/10.1017/jfm.2014.25.

Full text
Abstract:
AbstractWe perform experiments to study the mixing of passive scalar by a buoyancy-induced turbulent flow in a long narrow vertical tank. The turbulent flow is associated with the downward mixing of a small flux of dense aqueous saline solution into a relatively large upward flux of fresh water. In steady state, the mixing region is of finite extent, and the intensity of the buoyancy-driven mixing is described by a spatially varying turbulent diffusion coefficient $\kappa _v(z)$ which decreases linearly with distance $z$ from the top of the tank. We release a pulse of passive scalar into either the fresh water at the base of the tank, or the saline solution at the top of the tank, and we measure the subsequent mixing of the passive scalar by the flow using image analysis. In both cases, the mixing of the passive scalar (the dye) is well-described by an advection–diffusion equation, using the same turbulent diffusion coefficient $\kappa _v(z)$ associated with the buoyancy-driven mixing of the dynamic scalar. Using this advection–diffusion equation with spatially varying turbulent diffusion coefficient $\kappa _v(z)$, we calculate the residence time distribution (RTD) of a unit mass of passive scalar released as a pulse at the bottom of the tank. The variance in this RTD is equivalent to that produced by a uniform eddy diffusion coefficient with value $\kappa _e= 0.88 \langle \kappa _v \rangle $, where $\langle \kappa _v \rangle $ is the vertically averaged eddy diffusivity. The structure of the RTD is also qualitatively different from that produced by a flow with uniform eddy diffusion coefficient. The RTD using $\kappa _v$ has a larger peak value and smaller values at early times, associated with the reduced diffusivity at the bottom of the tank, and manifested mathematically by a skewness $\gamma _1\approx 1.60$ and an excess kurtosis $\gamma _2\approx 4.19 $ compared to the skewness and excess kurtosis of $\gamma _1\approx 1.46$, $\gamma _2 \approx 3.50$ of the RTD produced by a constant eddy diffusion coefficient with the same variance.
APA, Harvard, Vancouver, ISO, and other styles
3

Carmona, René, and François Delarue. "Singular FBSDEs and scalar conservation laws driven by diffusion processes." Probability Theory and Related Fields 157, no. 1-2 (November 5, 2012): 333–88. http://dx.doi.org/10.1007/s00440-012-0459-7.

Full text
APA, Harvard, Vancouver, ISO, and other styles
4

Watanabe, Tsutomu, Marie Takagi, Kou Shimoyama, Masayuki Kawashima, Naoyuki Onodera, and Atsushi Inagaki. "Coherent Eddies Transporting Passive Scalars Through the Plant Canopy Revealed by Large-Eddy Simulations Using the Lattice Boltzmann Method." Boundary-Layer Meteorology 181, no. 1 (July 9, 2021): 39–71. http://dx.doi.org/10.1007/s10546-021-00633-1.

Full text
Abstract:
AbstractA double-distribution-function lattice Boltzmann model for large-eddy simulations of a passive scalar field in a neutrally stratified turbulent flow is described. In simulations of the scalar turbulence within and above a homogeneous plant canopy, the model’s performance is found to be comparable with that of a conventional large-eddy simulation model based on the Navier–Stokes equations and a scalar advection–diffusion equation in terms of the mean turbulence statistics, budgets of the second moments, power spectra, and spatial two-point correlation functions. For a top-down scalar, for which the plant canopy serves as a distributed sink, the variance and flux of the scalar near the canopy top are predominantly determined by sweep motions originating far above the canopy. These sweep motions, which have spatial scales much larger than the canopy height, penetrate deep inside the canopy and cause scalar sweep events near the canopy floor. By contrast, scalar ejection events near the canopy floor are induced by coherent eddies generated near the canopy top. The generation of such eddies is triggered by the downward approach of massive sweep motions to existing wide regions of weak ejective motions from inside to above the canopy. The non-local transport of scalars from above the canopy to the canopy floor, and vice versa, is driven by these eddies of different origins. Such non-local transport has significant implications for the scalar variance and flux budgets within and above the canopy, as well as the transport of scalars emitted from the underlying soils to the atmosphere.
APA, Harvard, Vancouver, ISO, and other styles
5

Song, Na, and Zaiming Liu. "Parameter Estimation for Stochastic Differential Equations Driven by Mixed Fractional Brownian Motion." Abstract and Applied Analysis 2014 (2014): 1–6. http://dx.doi.org/10.1155/2014/942307.

Full text
Abstract:
We study the asymptotic properties of minimum distance estimator of drift parameter for a class of nonlinear scalar stochastic differential equations driven by mixed fractional Brownian motion. The consistency and limit distribution of this estimator are established as the diffusion coefficient tends to zero under some regularity conditions.
APA, Harvard, Vancouver, ISO, and other styles
6

Coti Zelati, Michele, and Grigorios A. Pavliotis. "Homogenization and hypocoercivity for Fokker–Planck equations driven by weakly compressible shear flows." IMA Journal of Applied Mathematics 85, no. 6 (October 6, 2020): 951–79. http://dx.doi.org/10.1093/imamat/hxaa035.

Full text
Abstract:
Abstract We study the long-time dynamics of 2D linear Fokker–Planck equations driven by a drift that can be decomposed in the sum of a large shear component and the gradient of a regular potential depending on one spatial variable. The problem can be interpreted as that of a passive scalar advected by a slightly compressible shear flow, and undergoing small diffusion. For the corresponding stochastic differential equation, we give explicit homogenization rates in terms of a family of time-scales depending on the parameter measuring the strength of the incompressible perturbation. This is achieved by exploiting an auxiliary Poisson problem, and by computing the related effective diffusion coefficients. Regarding the long-time behavior of the solution of the Fokker–Planck equation, we provide explicit decay rates to the unique invariant measure by employing a quantitative version of the classical hypocoercivity scheme. From a fluid mechanics perspective, this turns out to be equivalent to quantifying the phenomenon of enhanced diffusion for slightly compressible shear flows.
APA, Harvard, Vancouver, ISO, and other styles
7

Jenny, Patrick, Joohwa S. Lee, Daniel W. Meyer, and Hamdi A. Tchelepi. "Scale analysis of miscible density-driven convection in porous media." Journal of Fluid Mechanics 749 (May 16, 2014): 519–41. http://dx.doi.org/10.1017/jfm.2014.229.

Full text
Abstract:
AbstractScale analysis of unstable density-driven miscible convection in porous media is performed. The main conclusions for instabilities in the developed (long time scales) regime are that (i) large-scale structures are responsible for the bulk of the production of concentration variance, (ii) variance dissipation is dominated by the small (diffusive) scales and that (iii) both the production and dissipation rates are independent of the Rayleigh number. These findings provide a strong basis for a new modelling approach, namely, large-mode simulation (LMS), for which closure is achieved by replacing the actual diffusivity with an effective one. For validation, LMS results for vertical flow in a homogeneous rectangular domain are compared with direct numerical simulations (DNS). Some of the analysis is based on the derivation and closure of the concentration mean and variance equations, whereby averaging over the ensemble of all possible initial perturbations is considered. While self-similar solutions are obtained for vertical, statistically one-dimensional fingering, triple correlation of concentration and scalar dissipation rate (rate at which the concentration variance decays due to diffusion) have to be modelled in the general case. For this purpose, an ensemble-averaged Darcy modelling (EADM) approach is proposed.
APA, Harvard, Vancouver, ISO, and other styles
8

Xia, Hua, Nicolas Francois, Horst Punzmann, Kamil Szewc, and Michael Shats. "Extreme concentration fluctuations due to local reversibility of mixing in turbulent flows." Modern Physics Letters B 32, no. 12n13 (May 10, 2018): 1840028. http://dx.doi.org/10.1142/s0217984918400286.

Full text
Abstract:
Mixing of a passive scalar in a fluid (e.g. a radioactive spill in the ocean) is the irreversible process towards homogeneous distribution of a substance. In a moving fluid, due to the chaotic advection [H. Aref, J. Fluid Mech. 143 (1984) 1; J. M. Ottino, The Kinematics of Mixing: Stretching,Chaos and Transport (Cambridge University Press, Cambridge, 1989)] mixing is much faster than if driven by molecular diffusion only. Turbulence is known as the most efficient mixing flow [B. I. Shraiman and E. D. Siggia, Nature 405 (2000) 639]. We show that in contrast to spatially periodic flows, two-dimensional turbulence exhibits local reversibility in mixing, which leads to the generation of unpredictable strong fluctuations in the scalar concentration. These fluctuations can also be detected from the analysis of the fluid particle trajectories of the underlying flow.
APA, Harvard, Vancouver, ISO, and other styles
9

Herlina, H., and J. G. Wissink. "Direct numerical simulation of turbulent scalar transport across a flat surface." Journal of Fluid Mechanics 744 (March 11, 2014): 217–49. http://dx.doi.org/10.1017/jfm.2014.68.

Full text
Abstract:
AbstractTo elucidate the physical mechanisms that play a role in the interfacial transfer of atmospheric gases into water, a series of direct numerical simulations of mass transfer across the air–water interface driven by isotropic turbulence diffusing from below has been carried out for various turbulent Reynolds numbers ($R_T=84,195,507$). To allow a direct (unbiased) comparison of the instantaneous effects of scalar diffusivity, in each of the DNS up to six scalar advection–diffusion equations with different Schmidt numbers were solved simultaneously. As far as the authors are aware this is the first simulation that is capable to accurately resolve the realistic Schmidt number, $\mathit{Sc}=500$, that is typical for the transport of atmospheric gases such as oxygen in water. For the range of turbulent Reynolds numbers and Schmidt numbers considered, the normalized transfer velocity $K_L$ was found to scale with $R_T^{-{1/2}}$ and $\mathit{Sc}^{-{1/2}}$, which indicates that the largest eddies present in the isotropic turbulent flow introduced at the bottom of the computational domain tend to determine the mass transfer. The $K_L$ results were also found to be in good agreement with the surface divergence model of McCready, Vassiliadou & Hanratty (AIChE J., vol. 32, 1986, pp. 1108–1115) when using a constant of proportionality of 0.525. Although close to the surface large eddies are responsible for the bulk of the gas transfer, it was also observed that for higher $R_T$ the influence of smaller eddies becomes more important.
APA, Harvard, Vancouver, ISO, and other styles
10

Antonov, N., M. Hnatich, D. Horváth, and M. Nalimov. "The Anomalous Diffusion of the Self-Interacting Passive Scalar in the Turbulent Environment." International Journal of Modern Physics B 12, no. 19 (July 30, 1998): 1937–62. http://dx.doi.org/10.1142/s0217979298001125.

Full text
Abstract:
Two variants of the statistical model of diffusing self-interacting passive scalar θ(x, t) driven by the incompressible Navier–Stokes turbulence were studied by means of the field-theoretical renormalization group technique and ∊-expansion scheme, where ∊ denotes the parameter of the forcing spectrum. Dual ∫ ddxdt[θ(x, t)]2 and triple ∫ ddxdt[θ(x, t)]3 interaction terms of the action represent two different mechanisms of the self-interaction matching two alternative values of the critical dimension: d c =4 and d c =6. The major part of the calculations was carried out in the one loop order, nevertheless, the inclusion of the specific two loop contributions represents the important step of the analysis of some renormalization group functions. In the basic model variant the effective action is renormalizable for the supercritical dimensions d > d c . This theory exhibits the presence of the asymptotical regime, which is stable for the inertial-conductive range of wave numbers. It was also shown that stability of this regime remains preserved for a variety of the parametric paths connecting domain ∊>0, d>d c with ∊<2, d=3. In the second model variant, the effective action is constructed to be renormalizable at dimensions d≥d c and to justify the realizability of the continuation from ∊>0, d>d c to ∊< 2, d=3. This variant of the model was analyzed using "double expansion" method with the expansion parameters (d-d c )/2 and ∊. The negative correction ζ(ζ≃0.039 for d=3) to the universal Richardson exponent 4/3 is the physical consequence stemming from the calculations.
APA, Harvard, Vancouver, ISO, and other styles
More sources

Dissertations / Theses on the topic "Scalar driven diffusion"

1

Larsson, Karl. "Scale-Space Methods as a Means of Fingerprint Image Enhancement." Thesis, Linköping University, Department of Science and Technology, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-2282.

Full text
Abstract:

The usage of automatic fingerprint identification systems as a means of identification and/or verification have increased substantially during the last couple of years. It is well known that small deviations may occur within a fingerprint over time, a problem referred to as template ageing. This problem, and other reasons for deviations between two images of the same fingerprint, complicates the identification/verification process, since distinct features may appear somewhat different in the two images that are matched. Commonly used to try and minimise this type of problem are different kinds of fingerprint image enhancement algorithms. This thesis tests different methods within the scale-space framework and evaluate their performance as fingerprint image enhancement methods.

The methods tested within this thesis ranges from linear scale-space filtering, where no prior information about the images is known, to scalar and tensor driven diffusion where analysis of the images precedes and controls the diffusion process.

The linear scale-space approach is shown to improve correlation values, which was anticipated since the image structure is flattened at coarser scales. There is however no increase in the number of accurate matches, since inaccurate features also tends to get higher correlation value at large scales.

The nonlinear isotropic scale-space (scalar dependent diffusion), or the edge- preservation, approach is proven to be an ill fit method for fingerprint image enhancement. This is due to the fact that the analysis of edges may be unreliable, since edge structure is often distorted in fingerprints affected by the template ageing problem.

The nonlinear anisotropic scale-space (tensor dependent diffusion), or coherence-enhancing, method does not give any overall improvements of the number of accurate matches. It is however shown that for a certain type of template ageing problem, where the deviating structure does not significantly affect the ridge orientation, the nonlinear anisotropic diffusion is able to accurately match correlation pairs that resulted in a false match before they were enhanced.

APA, Harvard, Vancouver, ISO, and other styles
2

Mignon, Ingrid. "Inducing large-scale diffusion of innovation : An integrated actor- and system-level approach." Doctoral thesis, Linköpings universitet, Projekt, innovationer och entreprenörskap, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-131029.

Full text
Abstract:
In order for the innovation process to be successful, not only do innovations need to be developed and reached the market, but, once they are available for users, they have to spread on a large scale. In the innovation literature, a complete explanation is lacking of why some innovations reach a phase of large-scale diffusion faster than others, including both actor- and system-level components. For instance, what drives and hinders adopters to decide to adopt the innovation on the actor and system levels, and how adopters who participate in the largescale diffusion handle the adoption process and the implementation of the innovation, are questions still unanswered. As a consequence, it remains unclear how the large-scale diffusion process can be facilitated and speeded up. This thesis addresses these issues by studying the case of renewable electricity (RE) innovations. After decades of technology development and improvements, RE innovations are now mature enough to be bought off-the-shelf by individuals and organizations. Yet, the pace of their large-scale diffusion is still too slow for countries to reach their RE generation targets and to limit global warming. Through qualitative and quantitative methods including 59 semi-structured interviews with adopters, project developers and experts in Sweden, France and Germany as well as a survey sent to the whole population of RE adopters in Sweden, an adopter perspective is taken in order to explore the adoption dynamics shaping large-scale diffusion of innovation. More specifically, the thesis identifies the drivers and challenges of adoption during large-scale diffusion and their impact on adoption decisions and strategies. The outcome of this work is presented in a compiling synthesis and six appended papers. Findings show that adopters are heterogeneous with regard to their characteristics, as well as to the drivers, challenges and strategies that affect their adoption processes. Depending on their perceptions, some adopters are more influenced by drivers and challenges than others and, as a consequence, adopters base their adoption decisions on different motives and follow different strategies to implement the innovation. Moreover, the results suggest that the dynamics that occur during the large-scale diffusion process does not only come from the actor level and the level of the system where the largescale diffusion takes place, but also from parallel systems, which are related to adopters and their contexts, including both the social networks and the industries they primarily belong. This makes adopters the central drivers of the innovation diffusion process and this distinguishes the dynamics of large-scale diffusion from the dynamics of innovation development and early diffusion, in which the innovation is the central component. Based on the findings about the adoption dynamics shaping large-scale diffusion, the thesis raises the need to consider large-scale diffusion as part of a new system, different from the innovation system and that acknowledges the specificities of this process. A tentative model accounting for the central role of adopters and for the interactions between adopters, the diffusion system and parallel systems is introduced. Finally, the implications of these findings for policy makers and managers are put forward. In particular, there is a need for policies acknowledging adopters’ heterogeneity as well as the new challenges of large-scale diffusion. Strategies developed by adopters can be a source of inspiration for policy-makers, who can for instance promote the use of intermediaries, of adopters’ task environment and networks, as well as the formation of coalitions among adopters.
APA, Harvard, Vancouver, ISO, and other styles

Book chapters on the topic "Scalar driven diffusion"

1

Föll, Fabian, Valerie Gerber, Claus-Dieter Munz, Berhand Weigand, and Grazia Lamanna. "On the Consideration of Diffusive Fluxes Within High-Pressure Injections." In Notes on Numerical Fluid Mechanics and Multidisciplinary Design, 195–208. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-53847-7_12.

Full text
Abstract:
Abstract Mixing characteristics of supercritical injection studies were analyzed with regard to the necessity to include diffusive fluxes. Therefore, speed of sound data from mixing jets were investigated using an adiabatic mixing model and compared to an analytic solution. In this work, we show that the generalized application of the adiabatic mixing model may become inappropriate for subsonic submerged jets at high-pressure conditions. Two cases are discussed where thermal and concentration driven fluxes are seen to have significant influence. To which extent the adiabatic mixing model is valid depends on the relative importance of local diffusive fluxes, namely Fourier, Fick and Dufour diffusion. This is inter alia influenced by different time and length scales. The experimental data from a high-pressure n-hexane/nitrogen jet injection were investigated numerically. Finally, based on recent numerical findings, the plausibility of different thermodynamic mixing models for binary mixtures under high pressure conditions is analyzed.
APA, Harvard, Vancouver, ISO, and other styles
2

Zia, R. K. P., and T. Blum. "An introduction to the statistical mechanics of driven diffusive systems." In Scale Invariance, Interfaces, and Non-Equilibrium Dynamics, 111–31. Boston, MA: Springer US, 1995. http://dx.doi.org/10.1007/978-1-4899-1421-7_5.

Full text
APA, Harvard, Vancouver, ISO, and other styles
3

Tomaselli, Venera, and Giulio Giacomo Cantone. "Multipoint vs slider: a protocol for experiments." In Proceedings e report, 91–96. Florence: Firenze University Press, 2021. http://dx.doi.org/10.36253/978-88-5518-304-8.19.

Full text
Abstract:
Since the broad diffusion of Computer-Assisted survey tools (i.e. web surveys), a lively debate about innovative scales of measure arose among social scientists and practitioners. Implications are relevant for applied Statistics and evaluation research since while traditional scales collect ordinal observations, data from sliders can be interpreted as continuous. Literature, however, report excessive times of completion of the task from sliders in web surveys. This experimental protocol is aimed at testing hypotheses on the accuracy in prediction and dispersion of estimates from anonymous participants who are recruited online and randomly assigned into tasks in recognition of shades of colour. The treatment variable is two scales: a traditional multipoint 0-10 multipoint vs a slider 0-100. Shades have a unique parametrisation (true value) and participants have to guess the true value through the scale. These tasks are designed to recreate situations of uncertainty among participants while minimizing the subjective component of a perceptual assessment and maximizing information about scale-driven differences and biases. We propose to test statistical differences in the treatment variable: (i) mean absolute error from the true value (ii), time of completion of the task. To correct biases due to the variance in the number of completed tasks among participants, data about participants can be collected through both pre-tasks acceptance of web cookies and post-tasks explicit questions.
APA, Harvard, Vancouver, ISO, and other styles
4

Wampler, Brian, Stephanie McNulty, and Michael Touchton. "South-to-South and Donor-driven Diffusion in Sub-Saharan Africa." In Participatory Budgeting in Global Perspective, 158–80. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780192897756.003.0007.

Full text
Abstract:
Governments in sub-Saharan Africa began to adopt PB in the early 2000s. The World Bank, USAID, DFID, and other international organization led the push to expand PB. By 2019, the region included more than nine hundred programs. PB’s diffusion across sub-Saharan Africa has led to its transformation in scale, rules, and impact. Most PB programs in sub-Saharan Africa focus on building accountability and allowing participants to select small-scale development projects. These programs are located both in major cities (Maputo, Nairobi) as well as in poor, rural areas across the region. These programs are intended to improve local governance, but the involvement of international donors means that local governments must address their concerns as well as those of participants. The programs also emphasize placing new development projects in poor, marginalized communities, thus retaining potential for improving well-being. This chapter documents these trends by focusing on PB in Kenya, Madagascar, Mozambique, Senegal, South Africa, and Uganda.
APA, Harvard, Vancouver, ISO, and other styles
5

Ciarli, Tommaso, Maria Savona, and Jodie Thorpe. "Innovation for Inclusive Structural Change." In The Challenges of Technology and Economic Catch-up in Emerging Economies, 349–76. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780192896049.003.0012.

Full text
Abstract:
The chapter proposes the foundations of an analytical framework to identify innovation pathways that lead to inclusive structural change in low- and medium-income countries (LMICs). Innovation pathways depend on how actors, interactions, and conditions affect the origin of innovation; the uptake of the innovations (adoption and diffusion); the impact of this diffusion on upgrading; the extent to which technological upgrading scales up to drive structural change and inclusion; the complementarity among these processes; and the potential trade-offs between structural change and inclusion. After delineating the analytical framework, the chapter focuses on applications of the framework to identify typical trade-offs between inclusion and structural change, and policy options to tackle these trade-offs and achieve outcomes of inclusive structural change. We finally propose a research agenda to build upon the framework and directly inform policies for inclusive structural change. The contribution of this work aims to respond to the recently increasing demand coming from international institutions, inter-departmental research funds, NGOs and national ministries, for improved knowledge to shape a more effective innovation policy for inclusive development in LMICs.
APA, Harvard, Vancouver, ISO, and other styles
6

Lee, Cheon-Pyo. "Mobile Business Applications." In Mobile Computing, 2163–68. IGI Global, 2009. http://dx.doi.org/10.4018/978-1-60566-054-7.ch174.

Full text
Abstract:
As an increasing number of organizations and individuals are dependent on mobile technologies to perform their tasks, various mobile applications have been rapidly introduced and used in a number of areas such as communications, financial management, information retrieval, and entertainment. Mobile applications were initially very basic and simple, but the introduction of higher bandwidth capability and the rapid diffusion of Internet-compatible phones, along with the innovations in the mobile technologies, allow for richer and more efficient applications. Over the years, mobile applications have primarily been developed in consumer-oriented areas where products such as e-mail, games, and music have led the market (Gebauer & Shaw, 2004). According to the ARC group, mobile entertainment service will generate $27 billion globally by 2008 with 2.5 billion users (Smith, 2004). Even though mobile business (m-business) applications have been slow to catch on mobile applications for consumers and are still waiting for larger-scale usage, m-business application areas have received enormous attention and have rapidly grown. As entertainment has been a significant driver of consumer-oriented mobile applications, applications such as delivery, construction, maintenance, and sales of mobile business have been drivers of m-business applications (Funk, 2003). By fall of 2003, Microsoft mobile solutions partners had registered more than 11,000 applications including e-mail, calendars and contacts, sales force automation, customer relationship management, and filed force automation (Smith, 2004). However, in spite of their huge potential and benefits, the adoption of m-business applications appears much slower than anticipated due to numerous technical and managerial problems.
APA, Harvard, Vancouver, ISO, and other styles
7

Valentine, Scott. "Wind Power in Germany." In Wind Power Politics and Policy. Oxford University Press, 2015. http://dx.doi.org/10.1093/oso/9780199862726.003.0007.

Full text
Abstract:
In the previous chapter, the malleability of Danish energy policy was highlighted as a key factor behind the successful diffusion of wind power in Denmark. This chapter examines wind power diffusion in Germany, and in the process highlights a different, though equally successful policy ideology. Compared to policy of its Nordic neighbor, wind power development policy in Germany has been far more structured and invariable. In fact, the success of Germany’s wind power development strategy often serves as an exemplar for proponents of consistent feed-in tariff regimes, which is considered by some to be the most effective strategy for driving wind power development. As this chapter will demonstrate, fostering wind power development in Germany is, like in other nations, a complex challenge involving dynamic interactions between government and nongovernment actors. As German wind power capacity expanded, there has been social dissent and utility opposition. Nevertheless, the German government has remained committed to aggressive wind power diffusion policies and has responded to emergent challenges in a remarkably unified manner wherein state, regional, and local government actors have formed integrated problem-solving networks. This chapter also highlights the seamless web of nation-specific STEP factors influencing wind power development that is apparent in Germany. As one pair of researchers observed, wind power development in Germany has been marked by “close interplay between the actors within the political system, technical and economic development, as well as social factors.” As has been the case in most industrialized nations, forces in support of wind power development began to amass during the two energy crises of the 1970s. As the government began to evaluate its alternative energy technology options, nuclear power and wind power emerged as the two most viable utility-scale options. In the 1970s, nuclear power in Germany enjoyed a modicum of developmental success. The nation’s first commercial nuclear power plant commenced operation in 1969. By 2010, nuclear power contributed approximately 22% to Germany’s electricity supply. However, nuclear power development has been contentious. Although there has been industrial support, there has also been strident public opposition, especially since Chernobyl.
APA, Harvard, Vancouver, ISO, and other styles
8

Saltzman, W. Mark. "Drug Modification." In Drug Delivery. Oxford University Press, 2001. http://dx.doi.org/10.1093/oso/9780195085891.003.0014.

Full text
Abstract:
Previous chapters present the characteristics of drug movement through the body. Diffusion is an essential mode of transport at the microscopic scale; concentration gradients drive a substantial fraction of the molecular movements within cells and the extracellular space. The confinement and regulated passage of molecules within compartments of a tissue or cell is also essential for function; membranes confine molecules to spatial locations and regulate transport between these isolated spaces (Chapter 5). Membranes frequently are the major obstacles to the entry or distribution of therapeutic compounds (Chapter 7). Therefore, much of the effort in drug design and drug delivery is devoted to overcoming these diffusional or membrane barriers. This chapter describes strategies for manipulating agents in order to increase their biological activity. The sections orbit a central assumption: i.e., agents can be modified to make analogous agents (analogs), which are chemically distinct from the original compound, but produce a similar biological effect. Nature uses a similar strategy, called “biotransformation” to assure elimination of many toxic compounds and drugs. Substantial chemical modification is often needed in order to impact physical properties that influence drug distribution such as stability or solubility; the challenge of drug modification is to identify chemical features that can be changed without sacrificing biological activity. Often, our understanding of the relationship between chemical structure and biological function for an agent is incomplete, making the rational production of analogs difficult. Drug modifications are frequently directed at altering properties that influence the concentration of the compound (i.e., its solubility), the duration of action (which is usually related to its stability in tissue), or the ability of drug molecules to move between compartments in tissues (which is often related to its permeability in membranes). A chemical modification can effect multiple properties, so these divisions are frequently not as distinct as the section headings suggest. Many agents are protected from degradation within tissues by binding. Binding provides a mechanism for sequestering an unstable or potent compound within a region of a tissue. Protective binding occurs frequently within the plasma and extracellular matrix (ECM); the complex molecular composition of these tissues provides many potential binding sites.
APA, Harvard, Vancouver, ISO, and other styles
9

Fawcett, W. Ronald. "Charge Transfer Equilibria at Interfaces." In Liquids, Solutions, and Interfaces. Oxford University Press, 2004. http://dx.doi.org/10.1093/oso/9780195094329.003.0013.

Full text
Abstract:
Processes in which charge is transferred from one phase to another at an interface make up an important class of interfacial reactions. Well-known examples are the reactions which occur at the electrodes of an electrochemical cell. These are electron transfer reactions, oxidation taking place at one electrode and reduction at the other. The early study of electrochemical cells provided valuable thermodynamic information about the redox processes occurring in them. When an electrochemical cell is a source of energy, for example, a battery, chemical energy is converted to electrical energy. When electrical energy is driven into an electrochemical cell from an external source, electrode reactions producing products of commercial interest are possible. Thus the general subject discussed here is of considerable practical importance. Another important class of interfacial charge transfer processes occurs at the membrane | solution interface. Some solute species can move into the membrane phase, whereas others cannot. When ions are involved in membrane selectivity, a potential drop is established at the interface. Ion transfer processes at membranes are extremely important in living organisms and form the basis for the functioning of the nervous system. Membranes are also involved in ion selective electrodes such as the ubiquitous pH electrode. These electrodes are often used in modern analytical techniques based on potentiometry. In the present chapter, the relationship between the electrode potential and the activity of the solution components in the cell is examined in detail. The connection between the Galvani potential difference at the electrode solution interface and the electrode potential on the standard redox scale is discussed. This leads to an examination of the extrathermodynamic assumption which allows one to define an absolute electrode potential. Ion transfer processes at the membrane | solution interface are then examined. Diffusion potentials within the membrane and the Donnan potentials at the interface are illustrated for both liquid and solid state membranes. Specific ion electrodes are described, and their various modes of sensing ion activities in an analyte solution discussed. The structure and type of membrane used are considered with respect to its selectivity to a particular ion over other ions.
APA, Harvard, Vancouver, ISO, and other styles
10

White, Robert E. "Soil–Water–Vine Relationships and Water Management." In Soils for Fine Wines. Oxford University Press, 2003. http://dx.doi.org/10.1093/oso/9780195141023.003.0008.

Full text
Abstract:
Water is a prerequisite for vine growth. It is essential for photosynthesis and to maintain the hydrated conditions and cell turgor necessary for a host of other bio­chemical processes in the plant. As we saw in chapter 4, diffusion of nutrient ions to the root, and their movement by mass flow into the vine’s “transpiration stream,” both depend on water. The volumetric water content θ, defined as the volume of water per unit vol­ume of soil (section 3.3.2), indicates how much water the soil can hold. How­ever, to understand what drives water movement in the soil, we must understand the forces acting on the water because they affect its potential energy. The energy status of soil water also influences its availability to plants. There is no absolute scale of potential energy. But we can measure changes in potential energy when useful work is done on a measured quantity of water or when the water itself does useful work. These changes are observed as changes in the free energy of water, which gives rise to the concept of soil water potential. The derivation of the soil water potential ψ (psi) is given in appendix 7. Historically, the energy status of soil water has been described by a number of terms related to soil water potential, such as pressure, suction, or hydraulic head. These terms ψ and their units are explained in box 6.1. The terms and head will be used in this book. Several forces act on soil water to decrease its free energy and give rise to compo­nent potentials. These are adsorption forces, capillary forces, osmotic forces, and gravity. Adsorption Forces. In very dry soils (relative humidity, RH, of the soil air <20%), water is adsorbed onto the clay and silt particles as a monolayer in which the molecules are hydrogen bonded to each other and the surface. With an in­crease in RH, more water molecules are adsorbed by hydrogen bonding to those on the surface. The charged surfaces of clay minerals also attract cations, and the electric field of the cation orients the polar water molecules around the ion to form a hydration shell, containing 6–12 water molecules.
APA, Harvard, Vancouver, ISO, and other styles

Conference papers on the topic "Scalar driven diffusion"

1

Mueschke, Nicholas J., and Malcolm J. Andrews. "Investigation of Scalar Measurement Error in Diffusion and Mixing Processes." In ASME 2004 International Mechanical Engineering Congress and Exposition. ASMEDC, 2004. http://dx.doi.org/10.1115/imece2004-60993.

Full text
Abstract:
In variable density, multi-fluid and reacting flows, a quantitative measure of the degree of molecular mixing is crucial to the development of turbulent transfer and mixing models. In a buoyancy-driven miscible mixing layer, we have found that the initial entrainment of unmixed fluid into the mixing layer causes a decrease in the measure of molecular mixedness at the centerplane of the mixing layer. Following the period of initial entrainment, the fluids within the mixing layer exhibits an increase in the degree of molecular mixing. Characterization of this and other mixing processes require scalar measurement devices with an adequate probe volume size. Spatial averaging, which occurs due to the finite probe volume size, can lead to errors in resolving the density or scalar gradients between pockets of unmixed fluids. Given a probe volume size and a priori knowledge of the functional profile of the diffusion layer being measured, we obtain an estimate for the measurement error due to spatial averaging that has occurred and make corrections accordingly. An analytical model for the measure of scalar mixing is developed as a predictor for the growth of scalar gradients in a variable scalar flow. The model is applied to a buoyancy-driven mixing layer with a Prandtl number of 7.
APA, Harvard, Vancouver, ISO, and other styles
2

Yadav, Rakesh, Ashoke De, and Sandeep Jain. "A Hybrid Flamelet Generated Manifold Model for Modeling Partially Premixed Turbulent Combustion Flames." In ASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/gt2017-65030.

Full text
Abstract:
In this work, a hybrid Flamelet Generated Manifold (FGM) method has been implemented in which both premixed and diffusion based laminar flame manifolds are generated independently and used within one solution framework to capture the multiple combustion regimes inside a combustor. The two manifolds are generated by solving the conservation of species and energy in a transformed space of mixture fraction and progress variable. The mixture averaged properties in a combustor are then calculated using a scalar weighted contribution of premixed and diffusion manifolds. This scalar represents the extent of premixing inside the combustor and its normalized value is obtained from a scalar product of the mean gradients of fuel and oxidizer mass fractions. A volume-weighted smoothing is performed on this normalized scalar to ensure smooth transition between the premixed to diffusion regimes and vice-versa, from one location to another location inside the combustor. This hybrid or multi-regime FGM approach is validated for two turbulent CH4-air partially premixed flames. The first flame chosen in the current work is a lifted turbulent flame, while the second flame is pilot-stabilized flame. First, the computations are performed for premixed- and diffusion-based laminar manifolds and then the results with hybrid models are presented. The results of the hybrid approach are compared for predicting the lift-off height, which is driven by the balance of turbulence and kinetics at any location. It is observed that the hybrid model leads to an improvement in the prediction of the lift-off height prediction. The new hybrid model is a generic representation of the FGM modeling, which enables its use without any a priori need to focus on a specific type of manifold creation for any combustor.
APA, Harvard, Vancouver, ISO, and other styles
3

Mehdizadeh, Minoo, and Goodarz Ahmadi. "Two-Dimensional Computer Simulation of Salinity Gradient Solar Pond Operation." In ASME 2014 4th Joint US-European Fluids Engineering Division Summer Meeting collocated with the ASME 2014 12th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/fedsm2014-21811.

Full text
Abstract:
This study is concerned with computer modeling of flow and thermal analysis of solar ponds with a salinity gradient. Solar ponds have been used as an efficient and environmentally friendly approach for collection of solar energy for low temperature thermal applications. A two-dimensional unsteady computational fluid dynamic (CFD) model was developed and used for numerical study of stability analysis of the pond, as well as heat and mass transfer in the salt gradient solar ponds. Salinity gradient was created in order to stabilize the pond and to restrict convective motions induced by buoyancy driven solar radiation heating during the period of operation. Fluent® commercial software was enhanced with the implementation of User Defined Functions (UDF) and was used in these simulations. The user defined scalar model was included for analyzing the convection and diffusion of the salt concentration in the solar pond. In addition, user defined functions were developed for relating the water density to temperature and salt concentration, as well as, the amount of solar radiation absorption in the solar pond as functions of thermo-physical properties. In the absence of flow exchange, the natural convection in the pond was simulated and the stability of the pond was verified. Development of salt concentration was also studied, and time evolution of temperature distribution in a small scale salinity gradient solar pond was analyzed. For the case of flow exchange at the bottom of the pond, the energy production was evaluated, and the temperature, concentration and flow field were simulated.
APA, Harvard, Vancouver, ISO, and other styles
4

Disimile, Peter, Norman Toy, and John Davis. "The Effect of Turbulent Length Scales on Flow Driven Diffusion Flames." In 2007 U.S. Air Force T&E Days. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2007. http://dx.doi.org/10.2514/6.2007-1628.

Full text
APA, Harvard, Vancouver, ISO, and other styles
5

Zhao, Baoxin, Chengzhong Xu, and Siyuan Liu. "A data-driven congestion diffusion model for characterizing traffic in metrocity scales." In 2017 IEEE International Conference on Big Data (Big Data). IEEE, 2017. http://dx.doi.org/10.1109/bigdata.2017.8258050.

Full text
APA, Harvard, Vancouver, ISO, and other styles
6

Pacheco, J. Rafael, KangPing Chen, and Arturo Pacheco-Vega. "Rate of Decay of a Passive Scalar in a Micro-Mixer and the Frequency of the Advecting Velocity Fields." In ASME 2009 Heat Transfer Summer Conference collocated with the InterPACK09 and 3rd Energy Sustainability Conferences. ASMEDC, 2009. http://dx.doi.org/10.1115/ht2009-88626.

Full text
Abstract:
In the current work, the mixing of a diffusive passive-scalar, e.g., thermal energy or species concentration, driven by electro-osmotic fluid motion being induced by an applied potential across a micro-channel is studied numerically. Secondary time-dependent periodic or random electric fields, orthogonal to the main stream, are applied to generate cross-sectional mixing. This investigation focuses on the mixing dynamics and its dependence on the frequency (period) of the driving mechanism. For periodic flows, the probability density function (PDF) of the scaled passive scalar (i.e., concentration), settles into a self-similar curve showing spatially repeating patterns. In contrast, for random flows there is a lack of self-similarity in the PDF for the interval of time considered in this investigation. The present study confirms an exponential decay of the variance of the concentration for the periodic and random flows.
APA, Harvard, Vancouver, ISO, and other styles
7

Rocha, George, and Rainer Kurz. "Field and Application Experience of the Titan 130 Industrial Gas Turbine." In ASME Turbo Expo 2001: Power for Land, Sea, and Air. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/2001-gt-0224.

Full text
Abstract:
The two-shaft Titan 130 industrial gas turbine was introduced into commercial service in 1998 and has gained field experience in mechanical-drive and compressor-set applications. A single-shaft configuration is also available for electrical power generation applications. The 14-MW class two-shaft engine is nominally rated at 19,500 hp with a simple-cycle efficiency of more than 35% at ISO operating conditions. It is available with two combustor options: a dry, low-pollutant emissions combustion system featuring Solar’s proven SoLoNOx technology or a diffusion-flame type combustor adapted from Solar’s proven Mars gas turbine. The Titan 130 gas turbine design is an aerodynamic scale of the existing Taurus 70 product. The unit features a modified Mars air compressor and turbine section components directly scaled from the Taurus 70, resulting in a low-risk product design well-suited for industrial service applications. A major element of the development strategy included an extended field evaluation trial in actual operating conditions to demonstrate overall product durability. The first Titan 130 mechanical-drive package was placed into service at a natural gas pipeline compressor station and successfully completed a planned 8000-hour field evaluation program. Extensive inspection and operating data have been evaluated and the unit continues to operate in normal commercial service. A mechanical-drive package requires the successful marriage between the driver and the driven equipment. Most applications require a combination of high efficiency and high performance flexibility. Emphasis was placed on providing excellent gas compressor coverage for this product. The successful application of such a compression system is discussed and supported by site test data. This paper provides details of the Titan 130 field evaluation program, design enhancements and typical compressor set application performance characteristics.
APA, Harvard, Vancouver, ISO, and other styles
8

Kee, Kerk F., Mona Sleiman, Michelle Williams, and Dominique Stewart. "The 10 Attributes that Drive Adoption and Diffusion of Computational Tools in E-Science." In XSEDE16: Diversity, Big Data, and Science at Scale. New York, NY, USA: ACM, 2016. http://dx.doi.org/10.1145/2949550.2949649.

Full text
APA, Harvard, Vancouver, ISO, and other styles
9

Takamure, Kotaro, Yasuhiko Sakai, Yasumasa Ito, and Koji Iwano. "Effect of the Large-Scale Structure on Turbulent Prandtl Number in a Turbulent Shear Layer." In ASME-JSME-KSME 2019 8th Joint Fluids Engineering Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/ajkfluids2019-4722.

Full text
Abstract:
Abstract We have run a Direct Numerical Simulation of a spatially developing shear mixing layer. The aim of this study is to clarify the influence of the large-scale structure on the turbulent Prandtl number PrT. As a main conclusion, PrT takes a small value (PrT ∼ 0.5) in the dominant region of the large-scale structure. The budget analyses for the Reynolds stress equation and the scalar flux equation revealed that the differences between the momentum and scalar transfer are caused by terms related to pressure (i.e., pressure-strain correlation term, pressure-scalar gradient correlation term, and pressure diffusion terms). Phenomenally, the momentum in the field where a large-scale vortex coexists tends to be transported toward the counter-gradient direction under the influence of pressure, but the scalar is transported toward the gradient direction. As a result, it is thought that the difference in the driving force between the momentum and scalar transport causes the decrease of the PrT.
APA, Harvard, Vancouver, ISO, and other styles
10

Raju, Mandhapati P., and James S. T’ien. "Heat and Mass Transports in Porous Wicks Driven by a Gas-Phase Diffusion Flame." In ASME 2005 Summer Heat Transfer Conference collocated with the ASME 2005 Pacific Rim Technical Conference and Exhibition on Integration and Packaging of MEMS, NEMS, and Electronic Systems. ASMEDC, 2005. http://dx.doi.org/10.1115/ht2005-72202.

Full text
Abstract:
A one dimensional stagnation point diffusion flame stabilized next to a porous wick is studied using a numerical model. The bottom end of the one-dimensional wick is dipped inside a liquid fuel (ethanol) reservoir. The liquid is drawn towards the surface of the wick through capillary action against gravity. The model combines heat and mass transfer equations in the porous media with phase change and gas-phase combustion equations to investigate steady-state flow structure in the porous wick and flame characteristics in the gas phase. In one-dimensional system, the only steady solution in the porous wick that is stable is found to be in the funicular regime. There are two regions in the wick: a vapor-liquid two-phase region near the surface exposed to the flame and a purely liquid region deep inside the wick. The physics behind the two-phase flow driven by capillarity and evaporation has been studied in detail. The coupling between the flame and the porous transport involves three different length scales: flame standoff distance, wick height above the reservoir and capillary rise. Attempt is made to study the effect of the non-dimensional numbers that contains these scales. In the limit of fast chemical kinetics (large Damkohler number), the computed results depend only on two non-dimensional ratios: the ratio of wick height to capillary rise and the ratio of wick height to flame standoff distance. Thus, a simplified similitude has been identified.
APA, Harvard, Vancouver, ISO, and other styles
You might also be interested in the extended bibliographies on the topic 'Scalar driven diffusion' for particular source types:
Journal articles
We offer discounts on all premium plans for authors whose works are included in thematic literature selections. Contact us to get a unique promo code!

To the bibliography