Bibliografias temáticas / Diffusion Equivalence

Literatura científica selecionada sobre o tema "Diffusion Equivalence"

Autor: Grafiati

Publicado: 27 de julho de 2024

Última modificação: 29 de julho de 2024

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Artigos de revistas sobre o assunto "Diffusion Equivalence"

Derbez, Patrick, e Marie Euler. "Equivalence of Generalised Feistel Networks". IACR Transactions on Symmetric Cryptology 2024, n.º 1 (1 de março de 2024): 412–40. http://dx.doi.org/10.46586/tosc.v2024.i1.412-440.

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This paper focuses on equivalences between Generalised Feistel Networks (GFN) of type-II. We introduce a new definition of equivalence which captures the concept that two GFNs are identical up to re-labelling of the inputs/outputs, and give a procedure to test this equivalence relation. Such two GFNs are therefore cryptographically equivalent for several classes of attacks. It induces a reduction o the space of possible GFNs: the set of the (k!)2 possible even-odd GFNs with 2k branches can be partitioned into k! different classes.This result can be very useful when looking for an optimal GFN regarding specific computationally intensive properties, such as the minimal number of active S-boxes in a differential trail. We also show that in several previous papers, many GFN candidates are redundant as they belong to only a few classes. Because of this reduction of candidates, we are also able to suggest better permutations than the one of WARP: they reach 64 active S-boxes in one round less and still have the same diffusion round that WARP. Finally, we also point out a new family of permutations with good diffusion properties.

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Goldberg, Maxim J., e Seonja Kim. "Equivalence of $$L_p$$ diffusion approximation and a function’s diffusion smoothness". Semigroup Forum 100, n.º 3 (28 de maio de 2019): 837–49. http://dx.doi.org/10.1007/s00233-019-10030-3.

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Harkola, Julia, e Arent Greve. "DIFFUSION OF TECHNOLOGY: COHESION OR STRUCTURAL EQUIVALENCE?" Academy of Management Proceedings 1995, n.º 1 (agosto de 1995): 422–26. http://dx.doi.org/10.5465/ambpp.1995.17536702.

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Malham, David G. "Toward Reality Equivalence in Spatial Sound Diffusion". Computer Music Journal 25, n.º 4 (dezembro de 2001): 31–38. http://dx.doi.org/10.1162/01489260152815279.

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Iagar, Razvan Gabriel, Guillermo Reyes e Ariel Sánchez. "Radial Equivalence of Nonhomogeneous Nonlinear Diffusion Equations". Acta Applicandae Mathematicae 123, n.º 1 (6 de junho de 2012): 53–72. http://dx.doi.org/10.1007/s10440-012-9714-2.

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Yairi, Micah B., e David A. B. Miller. "Equivalence of diffusive conduction and giant ambipolar diffusion". Journal of Applied Physics 91, n.º 7 (abril de 2002): 4374–81. http://dx.doi.org/10.1063/1.1453508.

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Popovych, Roman O., e Nataliya M. Ivanova. "Potential equivalence transformations for nonlinear diffusion–convection equations". Journal of Physics A: Mathematical and General 38, n.º 14 (22 de março de 2005): 3145–55. http://dx.doi.org/10.1088/0305-4470/38/14/006.

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Skal, Asya S. "Equivalence in Mapping of Conductivity, Elasticity and Diffusion Equations Appears or Disappears". Modern Physics Letters B 12, n.º 29n30 (30 de dezembro de 1998): 1227–35. http://dx.doi.org/10.1142/s0217984998001451.

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Equivalence in mapping of diffusion and conductivity equations appears when diffusion and conductivity belong to the same universality class and disappears in the opposite case. For asymptotic long-time behavior one exponent of regular diffusion coefficient above the threshold [Formula: see text] and two below the threshold [Formula: see text] and [Formula: see text] are introduced, using the conductivity critical exponent (μ and s) and the Hall coeffcient critical exponent Re(p-pc)-g if R2/R1→1 and Re(p-pc)2s if R2/R1→1 and p<pc. In the first two cases equivalence between the diffusion and conductivity problems are disappear. A problem with this analogy lies in an intrinsic property that for percolation lattice the diffusion coeffcient is not a self-averaging quantity unlike the conductivity. Analogy between conductivity and elasticity appears for scalar forces and disappears for vector forces. The latter leads to new equivalence between elasticity and conductivity in a magnetic field. The new formulae for a real part of dielectric constant in the static limit for p>pc and the low-frequency ac conductivity are determined due to the new critical exponent for regular diffusion.

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Kim, Heeyoun, e Juyoung Byun. "Development of HLB3-002 (recombinant human PH20 stand-alone) and its applicability as an anticancer diffusion agent." Journal of Clinical Oncology 42, n.º 16_suppl (1 de junho de 2024): e15195-e15195. http://dx.doi.org/10.1200/jco.2024.42.16_suppl.e15195.

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e15195 Background: HLB3-002 is a standalone of Halozyme's rHuPH20 (Original) and has the same amino acid sequence. HLB3-002 is being developed as a drug diffusion agent that decomposes subcutaneous hyaluronan, allowing substances such as anticancer drugs to be administered subcutaneously. This study was conducted to compare the in vivo efficacy and PK of original and HLB3-002 to confirm equivalence and thereby prove its applicability as a drug diffusion agent. Methods: In the in vivo efficacy test, Trypan blue was mixed with each original and HLB3-002 and administered subcutaneously to confirm diffusion and reconstruction equivalence in the nude mouse. The PK test was conducted using Rituximab, prepared in the same formulation as Rituximab SC by adding HLB3-002. A single dose was administered subcutaneously to the nape of the rat, and 12 points were collected for 28 days. The PK samples were measured by ELISA. When the Cmax and AUClast ratios of Rituximab between 2 groups were within 80.00 to 125.00%, they were evaluated as biologically equivalent. Results: As a result of efficacy test, the diffusion area of HLB3-002 was 104.7% compared to the original, which was confirmed to have an equivalent diffusion efficacy. In the skin reconstruction test, it was confirmed that both original and HLB3-002 rebuilt the skin layer to a similar to the negative control after 48 hours. As a result of the PK, Compared to Rituximab SC, the Cmax of Rituximab+HLB3-002 was similar at 98.53% and AUClast at 95.50%. Conclusions: Through an in vivo efficacy and PK test, we confirmed an equivalent drug diffusion effect, confirming that HLB3-002 applicability as an anticancer drug diffusion agent.[Table: see text]

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Jespersen, Sune Nørhøj. "Equivalence of double and single wave vector diffusion contrast at low diffusion weighting". NMR in Biomedicine 25, n.º 6 (2 de dezembro de 2011): 813–18. http://dx.doi.org/10.1002/nbm.1808.

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Mais fontes

Teses / dissertações sobre o assunto "Diffusion Equivalence"

Yan, Zifei. "Equivalence Transformations for a System of a Biological Reaction Diffusion Model". Thesis, Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-2201.

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A biological reaction diusion model has gained much attention recently. This model is formulated as a system of nonlinear partial dierential equations that contains an unknown function of one dependent variable. How to determine this unknown function is complicated but also useful. This model is considered in this master thesis. The generators of the equivalence groups and invariant solutions are calculated.

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Rispo, Adrien. "Modélisation neutronique avancée des interfaces avec la chaîne SCIENCE V2 pour la remontée axiale du flux dans les réacteurs REP". Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPASP034.

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L'objectif de la thèse est de comprendre puis réduire les biais sur la distribution axiale de puissance de la chaîne de calcul SCIENCE de FRAMATOME en comparaison aux simulations Monte-Carlo. L'enjeu industriel est d'estimer précisément la remontée de puissance en extrémité de colonne fissile, à l'interface avec le réflecteur. Cette surpuissance locale est nommée PIC1, pour pic de puissance dans le premier centimètre de combustible. Ce phénomène local étant très dépendant du type d'assemblage, les comparaisons sont réalisées pour six types d'assemblages différents représentatifs du parc français, afin de quantifier les écarts sur le PIC1. Une analyse des différentes sources de biais permet de déterminer une nouvelle structure du schéma actuel de SCIENCE, notamment sur l'équivalence réalisée dans le calcul des données du réflecteur axial, afin de réduire ces biais.Un nouveau schéma d'équivalence réflecteur est développé durant la thèse, permettant un gain en précision sur le PIC1 sur les configurations utilisées précédemment, ainsi que sur des configurations perturbées et avec un environnement. Il permet également un couplage avec le Monte-Carlo, en utilisant les sections efficaces homogénéisées comme données d'entrée pour l'échelle cœur. L'utilisation de plusieurs codes de transport déterministes montre l'importance du traitement 3D dans la résolution de l'équation de Boltzmann.Le nouveau schéma apporte également un gain de précision en évolution en comparant l'apport du nouveau schéma par rapport aux calculs équivalents avec SCIENCE de production et le Monte-Carlo. Une discussion sur la méthode d'implémentation de ce nouveau schéma dans SCIENCE de production est discutée, notamment sur la méthode de génération des sections efficaces à l'échelle réseau
The aim of this thesis is to understand and then reduce the biases in the axial power distribution between FRAMATOME's SCIENCE calculation chain and Monte-Carlo simulations. The industrial challenge is to accurately estimate the power increase at the bottom of the fissile column, at the interface with the reflector. This local overpower is called PIC1, for peak power in the first centimeter of fuel. As this local phenomenon highly depends on the assembly type, PIC1 comparisons are made for six different assembly types, all representative of the French fleet. An analysis of the various sources of bias is performed to determine a new calculation scheme for SCIENCE.A new reflector scheme based on an improved equivalence was developed during the thesis, enabling a gain in PIC1 accuracy for all configurations, but also on perturbed and with an environment configurations. It also enables a coupling with Monte Carlo, using homogenized cross sections as input data for the core level. The use of several deterministic transport codes demonstrates the importance of the 3D contribution to solve the Boltzmann equation.The new scheme also increases accuracy for depletion calculation. The way to implement the new scheme in SCIENCE for industrial studies is discussed, with an emphasis on the method to generate macroscopic cross-sections at the lattice level

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Dranev, Yury. "Equivalent Martingale measures and option pricing in jump-diffusion markets". Thesis, University of Ottawa (Canada), 2004. http://hdl.handle.net/10393/10794.

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One of the key questions in financial mathematics is the choice of an appropriate model for the financial market. There are a number of models available, such as Geometrical Brownian motion and different types of Levy processes, that are not general enough to reflect all the characteristics of fluctuations in stock price but for which the parameters can be estimated with relative ease. There are more general semimartingale models for which parameter estimation and numerical calculation become very difficult questions. The goal of this thesis is to present a tractable model for which we can carry out computations, and it seems that by varying the parameters this model can be related to real market data. We will use the equivalent measure approach to obtain estimates of the price of European call options for our model. Since our market is incomplete, a consequence of the inclusion of jump processes in the model, we will choose the "best" equivalent martingale measure by applying various techniques and compare the results for different choices. We will also illustrate how this theory works on particular examples. We consider applications not only to the cases of continuous and Levy process markets but also to cases that reflect the main advantages of our jump diffusion model. Finally we numerically illustrate option pricing in our setting.

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Liu, Yan. "In-vivo evaluation of brain structure in preterm neonates at term-equivalent time: contribution of diffusion tensor imaging and probabilistic tractography". Doctoral thesis, Universite Libre de Bruxelles, 2012. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209726.

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The preterm delivery (<37 weeks gestation) rates are generally 5-9% in Europe, 12-13% in the US, and each year about 13 millions preterm infants are born worldwide (MacDorman and Mathews, 2009; Slattery and Morrison, 2002). The early exposure to the extra-uterine environment increases the risks of perinatal brain injury, involving more often the white matter. The white matter injury is characterized by a potential subsequent occurrence of cognitive problems, of developmental delay and of major motor deficits (e.g. cerebral palsy).

The most widely used imaging technique for studying neonatal brain is cranial ultrasound that can be performed at bedside and detects major brain abnormalities (hemorrhage, infarctions, cysts, dilatation of the lateral ventricles). However, it has a poor sensitivity for non-cystic or diffuse white matter abnormalities (WMA), the most common form of white matter injury in preterm infants. In comparison to ultrasound, MR (magnetic resonance) imaging has been reported to be superior in detecting WMA and is considered as an essential modality for imaging the neonatal brain. The standard sequences (e.g. T1-, T2-weighted imaging) are routinely performed for assessing not only brain anatomy, but also for evaluating brain lesions. Nevertheless, ¡§conventional MR imaging¡¨ has been criticized because it is limited in qualitative assessment and it does not provide information on the extent of specific white matter pathways injuries.

Currently, diffusion tensor imaging (DTI) enables more detailed exploration of white matter microstructure. Furthermore, DTI is now the best in vivo technique capable of delineating white matter pathways and quantifying microstructural changes not visible on conventional MR imaging. Diffusion tensor tractography allows the reconstruction of the principal white matter fibers. Moreover, it also provides diffusion indices like fractional anisotropy (FA), mean diffusivity (MD), longitudinal diffusivity (£f//), transverse diffusivity (£f¢r) that help assess the changes in fiber tracts, even before myelination becomes histologically evident.

Structural MR imaging studies performed in neonates are scarce. A number of essential questions are still under debate, concerning the normal white matter structure, as well as premature brain injury. First, left language lateralization and right handedness are complex phenomena incompletely understood and the question rises whether structural lateralization already exist in healthy preterm neonates at term-equivalent age. Second, it is of interest to know whether gender-related structural differences exist in healthy preterm neonates. Finally, in the assessment of preterm brain injury, the relationship between WMA on conventional imaging and altered diffusion indices in fiber tracts is still unclear. Therefore, the aims of the thesis were to investigate the brain structure in a population of preterm neonates at term-equivalent age by DTI and probabilistic tractography.

The first part of this thesis (Study I and Study II) was devoted to the study of white matter structural characteristics in healthy preterm neonates. Previous studies have shown that structural asymmetries in language and motor related fibers are present in adults and in infants (Dubois et al. 2009; Westerhausen et al. 2007). Our hypothesis was that these structural asymmetries are already present in preterm neonates at term-equivalent age. In Study I, DTI and probabilistic tractography were performed and we found volume and microstructural asymmetries in the language related parieto-temporal superior longitudinal fasciculi (SLF), in the motor related corticospinal tract (CST) and in the motor part of the superior thalamic radiation (STR) as well. In Study II, we found that compared to boys, girls have larger relative tract volumes and an advanced maturation in language and motor related fiber tracts.

The second part of this thesis (Study III) investigated whether WMA on conventional MR imaging are related to abnormalities within the fiber tract microstructures. WMA were classified as normal, mild, moderate and severe according to Woodward¡¦s classification (Woodward et al. 2006). Woodward and colleagues studied a large population (167 infants) of preterm infants at term equivalent age with MRI. They demonstrated that WMA were important predictors of neurological outcomes by comparing their results with the neurological outcomes of those infants at corrected age of two. We found that compared to neonates with no abnormalities, infants with mild abnormalities have significantly higher ƒÜ¢r in the right CST, the left anterior thalamic radiation (ATR), the left sensory STR and bilateral motor STR. Those findings might be related to injuries of premyelinating oligodendrocytes resulting in subsequent failure of both development and ensheathment of axons. Considering that those fiber tracts connect important cortical zones, microstructural changes in those fiber tracts might be responsible for the later neurodevelopment deficits in motor and cognitive functions.

We concluded that structural asymmetries and gender differences in motor and language related fibers are present in healthy preterm neonates at term-equivalent age well before the development of speech and hand preference. Structural asymmetries and gender differences have to be considered in neonatal white matter assessment. Finally, altered DTI indices are associated with WMA on conventional MR imaging in preterm neonates. Our results suggest that disrupted premyelination is the major correlate with WMA rather than axonal pathology. Non-invasive DTI and tractography constitute an additional tool for the assessment of white matter injuries, as it could provide more adequate diagnostic information on brain microstructure in preterm neonates at term-equivalent age.
Doctorat en Sciences médicales
info:eu-repo/semantics/nonPublished

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POINSOT, ISABELLE. "Etude de quelques proprietes physiques de films minces de cristaux liquides smectiques c et o par une methode equivalente a la diffusion de lumiere". Université Louis Pasteur (Strasbourg) (1971-2008), 1996. http://www.theses.fr/1996STR13266.

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Dans un premier temps, nous avons elabore une methode originale de mesure, en valeur absolue, des constantes elastiques orientationnelles associees aux distorsions elastiques du champ du directeur resultant des fluctuations thermodynamiques moleculaires. Ce procede de mesure s'appuie sur les proprietes de birefringence des phases smectiques inclinees. En effet, les fluctuations orientationnelles du directeur se traduisent, sous microscope polarisant, par des fluctuations de l'intensite lumineuse. La mesure de ces fluctuations lumineuses suivie d'une decomposition en termes de fourier constitue donc une voie d'acces a ces constantes elastiques. Le montage experimental necessite simplement un microscope polarisant, une camera video et un ordinateur. On obtient alors pour chaque vecteur d'onde accessible la valeur moyenne de l'amplitude de fluctuation. Un ajustement de la courbe conduit ensuite a la determination non seulement des constantes elastiques mais egalement de la polarisation electrique. La connaissance de ces parametres permet enfin de deduire les viscosites orientationnelles des fonctions de correlation. Nous avons dans un second temps applique ce procede a l'etude de films minces de cristaux liquides a savoir des films suspendus et des films induits a la surface de gouttes isotropes en phases smectiques c et o d'epaisseur comprise entre 5 et 200 couches moleculaires. Les constantes elastiques obtenues sont pour les trois composes utilises de meme grandeur, mais sont d'un ordre de grandeur superieures a celles obtenues pour les nematiques. Ce resultat est conforme aux previsions dans le sens ou la phase smectique est plus ordonnee que la phase nematique. Une forte anisotropie des proprietes elastiques a egalement ete mise en evidence. Elle est independante du compose etudie, de l'epaisseur et de la temperature, et semble de ce fait etre une caracteristique des smectiques.

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Thorsell, Thomas. "Advances in Thermal Insulation : Vacuum Insulation Panels and Thermal Efficiency to Reduce Energy Usage in Buildings". Doctoral thesis, KTH, Byggnadsteknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-90745.

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We are coming to realize that there is an urgent need to reduce energy usage in buildings and it has to be done in a sustainable way. This thesis focuses on the performance of the building envelope; more precisely thermal performance of walls and super insulation material in the form of vacuum insulation. However, the building envelope is just one part of the whole building system, and super insulators have one major flaw: they are easily adversely affected by other problems in the built environment. Vacuum Insulation Panels are one fresh addition to the arsenal of insulation materials available to the building industry. They are composite material with a core and an enclosure which, as a composite, can reach thermal conductivities as low as 0.004 W/(mK). However, the exceptional performance relies on the barrier material preventing gas permeation, maintaining a near vacuum into the core and a minimized thermal bridge effect from the wrapping of barrier material round the edge of a panel. A serpentine edge is proposed to decrease the heat loss at the edge. Modeling and testing shows a reduction of 60% if a reasonable serpentine edge is used. A diffusion model of permeation through multilayered barrier films with metallization coatings was developed to predict ultimate service life. The model combines numerical calculations with analytical field theory allowing for more precise determination than current models. The results using the proposed model indicate that it is possible to manufacture panels with lifetimes exceeding 50 years with existing manufacturing. Switching from the component scale to the building scale; an approach of integrated testing and modeling is proposed. Four wall types have been tested in a large range of environments with the aim to assess the hygrothermal nature and significance of thermal bridges and air leakages. The test procedure was also examined as a means for a more representative performance indicator than R-value (in USA). The procedure incorporates specific steps exposing the wall to different climate conditions, ranging from cold and dry to hot and humid, with and without a pressure gradient. This study showed that air infiltration alone might decrease the thermal resistance of a residential wall by 15%, more for industrial walls. Results from the research underpin a discussion concerning the importance of a holistic approach to building design if we are to meet the challenge of energy savings and sustainability. Thermal insulation efficiency is a main concept used throughout, and since it measures utilization it is a partial measure of sustainability. It is therefore proposed as a necessary design parameter in addition to a performance indicator when designing building envelopes. The thermal insulation efficiency ranges from below 50% for a wood stud wall poorly designed with incorporated VIP, while an optimized design with VIP placed in an uninterrupted external layer shows an efficiency of 99%, almost perfect. Thermal insulation efficiency reflects the measured wall performance full scale test, thus indicating efficiency under varied environmental loads: heat, moisture and pressure. The building design must be as a system, integrating all the subsystems together to function in concert. New design methodologies must be created along with new, more reliable and comprehensive measuring, testing and integrating procedures. New super insulators are capable of reducing energy usage below zero energy in buildings. It would be a shame to waste them by not taking care of the rest of the system. This thesis details the steps that went into this study and shows how this can be done.
QC 20120228

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Penny, Melissa. "Mathematical modelling of dye-sensitised solar cells". Queensland University of Technology, 2006. http://eprints.qut.edu.au/16270/.

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This thesis presents a mathematical model of the nanoporous anode within a dyesensitised solar cell (DSC). The main purpose of this work is to investigate interfacial charge transfer and charge transport within the porous anode of the DSC under both illuminated and non-illuminated conditions. Within the porous anode we consider many of the charge transfer reactions associated with the electrolyte species, adsorbed dye molecules and semiconductor electrons at the semiconductor-dye- electrolyte interface. Each reaction at this interface is modelled explicitly via an electrochemical equation, resulting in an interfacial model that consists of a coupled system of non-linear algebraic equations. We develop a general model framework for charge transfer at the semiconductor-dye-electrolyte interface and simplify this framework to produce a model based on the available interfacial kinetic data. We account for the charge transport mechanisms within the porous semiconductor and the electrolyte filled pores that constitute the anode of the DSC, through a one- dimensional model developed under steady-state conditions. The governing transport equations account for the diffusion and migration of charge species within the porous anode. The transport model consists of a coupled system of non-linear differential equations, and is coupled to the interfacial model via reaction terms within the mass-flux balance equations. An equivalent circuit model is developed to account for those components of the DSC not explicitly included in the mathematical model of the anode. To obtain solutions for our DSC mathematical model we develop code in FORTRAN for the numerical simulation of the governing equations. We additionally employ regular perturbation analysis to obtain analytic approximations to the solutions of the interfacial charge transfer model. These approximations facilitate a reduction in computation time for the coupled mathematical model with no significant loss of accuracy. To obtain predictions of the current generated by the cell we source kinetic and transport parameter values from the literature and from experimental measurements associated with the DSC commissioned for this study. The model solutions we obtain with these values correspond very favourably with experimental data measured from standard DSC configurations consisting of titanium dioxide porous films with iodide/triiodide redox couples within the electrolyte. The mathematical model within this thesis enables thorough investigation of the interfacial reactions and charge transport within the DSC.We investigate the effects of modified cell configurations on the efficiency of the cell by varying associated parameter values in our model. We find, given our model and the DSC configuration investigated, that the efficiency of the DSC is improved with increasing electron diffusion, decreasing internal resistances and with decreasing dark current. We conclude that transport within the electrolyte, as described by the model, appears to have no limiting effect on the current predicted by the model until large positive voltages. Additionally, we observe that the ultrafast injection from the excited dye molecules limits the interfacial reactions that affect the DSC current.

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Penny, Melissa. "Mathematical modelling of dye-sensitised solar cells". Thesis, Queensland University of Technology, 2006. https://eprints.qut.edu.au/16270/1/Melissa_Penny_Thesis.pdf.

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Farrell, Troy W. "The mathematical modelling of primary alkaline battery cathodes". Thesis, Queensland University of Technology, 1998.

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Fialka, Jiří. "Měření parametrů piezoelektrických materiálů". Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2009. http://www.nusl.cz/ntk/nusl-217770.

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The master’s thesis deals with the piezoelectric coefficients, the resonance frequency and especially the piezoelectric constants verification. With the assistance of several devices, for instance LCR-meter HIOKI 3532, impedance analyzer Agilent 4294A and LCR-meter Agilent E4980A, the resonance and the anti-resonance frequencies as well as impedance and capacitance of samples are measured. The paper opens with the theory of the piezoelectric phenomenon and the difference between direct and indirect piezoelectric phenomenon, it also describes the basic behaviour of a piezoelectric ceramic element during mechanical straining or applied voltage. Further, the paper concerns the description of various piezoelectric constants and their calculations. Subsequent part of the paper is devoted to the temperature dependence of the main piezoelectric parameters of PZT ceramics. The materials coefficients are delineated as a function of temperature of the piezoelectric charge coefficients dij, relative permittivity r, electromechanical coupling factor kij and frequency constants Ni. One of the chapters also determines the piezoelectric charge constant d33 of PZT ceramics by laser interferometer and compares it with the value measured by resonance methods. The surface displacement was measured by a single-beam interferometer Polytec OFV-5000. The results of measurements of piezoelectric charge coefficients d33 acquired by the first and the second method are identical. The last section of the paper is focused on different methods of experimental studies on the characteristics of heat transfer by diffusing heat through conduction between the silver-plated surface of cylinder made of PZT ceramics. The effect on the resonance and the anti-resonance frequencies is monitored. There after, the real heat, determined by thermo camera and the physical model of heat transfer created in program COMSOL Multiphysics, is analysed.

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Livros sobre o assunto "Diffusion Equivalence"

Rajeev, S. G. The Navier–Stokes Equations. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198805021.003.0003.

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When different layers of a fluid move at different velocities, there is some friction which results in loss of energy and momentum to molecular degrees of freedom. This dissipation is measured by a property of the fluid called viscosity. The Navier–Stokes (NS) equations are the modification of Euler’s equations that include this effect. In the incompressible limit, the NS equations have a residual scale invariance. The flow depends only on a dimensionless ratio (the Reynolds number). In the limit of small Reynolds number, the NS equations become linear, equivalent to the diffusion equation. Ideal flow is the limit of infinite Reynolds number. In general, the larger the Reynolds number, the more nonlinear (complicated, turbulent) the flow.

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Capítulos de livros sobre o assunto "Diffusion Equivalence"

Nagasawa, Masao. "Equivalence of Diffusion and Schrödinger Equations". In Schrödinger Equations and Diffusion Theory, 89–114. Basel: Birkhäuser Basel, 1993. http://dx.doi.org/10.1007/978-3-0348-8568-3_4.

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Brox, Thomas, Martin Welk, Gabriele Steidl e Joachim Weickert. "Equivalence Results for TV Diffusion and TV Regularisation". In Scale Space Methods in Computer Vision, 86–100. Berlin, Heidelberg: Springer Berlin Heidelberg, 2003. http://dx.doi.org/10.1007/3-540-44935-3_7.

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Zhao, Z. "An Equivalence Theorem for Schrödinger Operators and its Applications". In Diffusion Processes and Related Problems in Analysis, Volume I, 245–60. Boston, MA: Birkhäuser Boston, 1990. http://dx.doi.org/10.1007/978-1-4684-0564-4_15.

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Feller, William, e Henry P. Mckean. "A DIFFUSION EQUIVALENT TO A COUNTABLE MARKOV CHAIN". In Selected Papers II, 391–94. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-16856-2_21.

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"III. Proving forcing equivalence". In Arnold Diffusion for Smooth Systems of Two and a Half Degrees of Freedom, 91–144. Princeton University Press, 2020. http://dx.doi.org/10.1515/9780691204932-005.

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Vadim, Kaloshin, e Zhang Ke. "Double Resonance: Forcing Equivalence". In Arnold Diffusion for Smooth Systems of Two and a Half Degrees of Freedom, 39–52. Princeton University Press, 2020. http://dx.doi.org/10.23943/princeton/9780691202525.003.0005.

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This chapter assesses the choice of cohomology and Aubry-Mather type at the double resonance. It begins by choosing cohomology classes for the (unperturbed) slow mechanical system. As in the case of single-resonance, the strategy is to choose a continuous curve in the cohomology space and prove forcing equivalence up to a residual perturbation. To do this, one needs to use the duality between homology and cohomology. The chapter then proves Aubry-Mather type for the perturbed slow mechanical system and reverts to the original coordinates. As the system has been perturbed, one needs to modify the choice of cohomology classes to connect the single and double resonances. Finally, the chapter proves Theorem 2.2, proving the main theorem.

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"Forcing equivalence between kissing cylinders". In Arnold Diffusion for Smooth Systems of Two and a Half Degrees of Freedom, 133–44. Princeton University Press, 2020. http://dx.doi.org/10.2307/j.ctvzgb6zj.16.

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Vadim, Kaloshin, e Zhang Ke. "Forcing equivalence between kissing cylinders". In Arnold Diffusion for Smooth Systems of Two and a Half Degrees of Freedom, 133–44. Princeton University Press, 2020. http://dx.doi.org/10.23943/princeton/9780691202525.003.0012.

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This chapter formulates and proves the jump mechanism. It constructs a variational problem which proves forcing equivalence for the original Hamiltonian using Definition 6.18. It first constructs a special variational problem for the slow mechanical system. A solution of this variational problem is an orbit “jumping” from one homology class to the other. The chapter then modifies this variational problem for the fast time-periodic perturbation of the slow mechanical system. This is achieved by applying the perturbative results established in Chapter 7. Recall the original Hamiltonian system near a double resonance can be brought to a normal form and this normal form, in turn, is related to the perturbed slow system through coordinate change and energy reduction. The variational problem for the perturbed slow system can then be converted to a variational problem for the original.

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"Weak KAM theory and forcing equivalence". In Arnold Diffusion for Smooth Systems of Two and a Half Degrees of Freedom, 55–65. Princeton University Press, 2020. http://dx.doi.org/10.2307/j.ctvzgb6zj.10.

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Vadim, Kaloshin, e Zhang Ke. "Weak KAM Theory and Forcing Equivalence". In Arnold Diffusion for Smooth Systems of Two and a Half Degrees of Freedom, 55–65. Princeton University Press, 2020. http://dx.doi.org/10.23943/princeton/9780691202525.003.0006.

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This chapter describes weak Kolmogorov-Arnold-Moser (KAM) theory and forcing relation. One change from the standard presentation is that one needs to modify the definition of Tonelli Hamiltonians to allow different periods in the t component. The chapter points out an alternative definition of the alpha function, namely, one can replace the class of minimal measures with the class of closed measures. It then considers a dual setting which corresponds to forward dynamic. It also looks at elementary solutions, static classes, and Peierls barrier. In many parts of the proof, the chapter studies the hyperbolic property of a minimizing orbit, for which the concept of Green bundles is very useful.

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Trabalhos de conferências sobre o assunto "Diffusion Equivalence"

Tracinà, Rita, e Mariano Torrisi. "Equivalence transformations for a class of advection-reaction-diffusion systems". In INTERNATIONAL CONFERENCE OF NUMERICAL ANALYSIS AND APPLIED MATHEMATICS: ICNAAM2022. AIP Publishing, 2024. http://dx.doi.org/10.1063/5.0210623.

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Torrisi, M., e R. Tracinà. "ON A CLASS OF REACTION DIFFUSION SYSTEMS: EQUIVALENCE TRANSFORMATIONS AND SYMMETRIES". In In Honor of the 65th Birthday of Antonio Greco. WORLD SCIENTIFIC, 2007. http://dx.doi.org/10.1142/9789812708908_0018.

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Simon, M. A., B. D. Baird e S. R. Gollahalli. "Characteristics of a Laminar Diffusion Flame in a Cross-Flow of Combustion Products". In ASME 2005 Power Conference. ASMEDC, 2005. http://dx.doi.org/10.1115/pwr2005-50030.

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This study was an investigation of the characteristics of a horizontal laminar diffusion flame established from a tubular burner in a buoyant vertical flow vitiated with combustion products created by a flat flame. The effects of varying flat flame equivalence ratio on these characteristics were studied. Applications of this study include exhaust gas recirculation (EGR), staged combustion in furnaces, and afterburners in jet engines. The fuel used for both the horizontal (cross-flow flame) and the flat flame in this study was propane. For a range of flat flame burner equivalence ratio (0.6 to 0.9), measurements of cross-flow flame length, and global emissions of NO were made. The mass flow rate of propane delivered to the cross-flow flame was held constant during these measurements. The flames were photographed with a digital camera. Profiles of combustion species concentrations and temperature were taken at 25% and 50% of the cross-flow flame length for flat flame burner equivalence ratios of 0.6 and 0.8, and for a non-combustion case (air flow only) in the flat flame. It was found that increasing the flat flame burner equivalence ratio caused an increase in the length of the cross-flow flame. The maximum temperature of the cross-flow flame decreased with increasing flat flame burner equivalence ratio. The introduction of the cross-flow flame increased the NO production in a flat flame with an equivalence ratio of 0.6, but did not significantly affect the NO production in a flat flame of an equivalence ratios of 0.7 or 0.8, and reduced it (by as much as 25%) in a flat flame of equivalence ratio of 0.9. This reduction of NO production and flame temperature and increase in flame length with increasing flat flame equivalence ratio was attributed to the reduction of oxygen available to the cross-flow flame. These results were supported with the in-flame combustion species concentration profiles.

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Kumar, Ankan, e Sandip Mazumder. "Investigation of Approximate Diffusion Models for the Prediction of Heterogeneous Combustion in Monolith Tubes". In ASME/JSME 2007 Thermal Engineering Heat Transfer Summer Conference collocated with the ASME 2007 InterPACK Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/ht2007-32073.

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In the case of heterogeneous reactions, diffusion is the only mechanism, locally, of transport of species to and from a surface. Thus, accurate prediction of diffusive transport is a prerequisite for accurate prediction of the operation of devices in which heterogeneous reactions occur. Three different diffusion models are examined from the standpoint of both accuracy and efficiency. Two of these models, namely the Dilute Approximation (DA) model and the Schmidt Number (SN) model, are approximate models, and are compared against a rigorous Multi-Component Diffusion (MCD) model derived from the Stefan-Maxwell equation. Both hydrogen-air and methane-air combustion in a monolith channel are studied. Inlet equivalence ratio, Reynolds number (flow rate), and wall temperature are considered as parameters. The results show that both the DA model and the SN model are accurate within 2% irrespective of the equivalence ratio or fuel—the worst accuracy being for hydrogen combustion. The DA model and the SN model produce almost identical results. In comparison to the MCD model, the DA model is approximately twice as computationally efficient, while the SN model is 3–4 times more efficient. The accuracy and efficiency of the SN model, in conjunction with its simplicity, makes it an attractive choice for the treatment of diffusion in catalytic combustion calculations.

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Zhang, Anqi, Daqing Piao e Charles F. Bunting. ""Spiral-planar equivalence" of steady state photon diffusion associated with a cylindrical applicator". In SPIE BiOS, editado por Bruce J. Tromberg, Arjun G. Yodh, Mamoru Tamura, Eva M. Sevick-Muraca e Robert R. Alfano. SPIE, 2011. http://dx.doi.org/10.1117/12.874898.

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Gao Jun e Zhu Jing-Fu. "The equivalence conditions of Wavelet Shrinkage and Anisotropic Diffusion and it's application in denosing". In 2012 International Conference on Measurement, Information and Control (MIC). IEEE, 2012. http://dx.doi.org/10.1109/mic.2012.6273351.

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Haldar, Justin P., e Richard M. Leahy. "The equivalence of linear spherical deconvolution and model-free linear transform methods for diffusion MRI". In 2013 IEEE 10th International Symposium on Biomedical Imaging (ISBI 2013). IEEE, 2013. http://dx.doi.org/10.1109/isbi.2013.6556523.

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Reumschüssel, Johann Moritz, Jakob G. R. von Saldern, Thomas Ludwig Kaiser, Thoralf Reichel, Jan Paul Beuth, Bernhard Ćosić, Franklin Genin, Kilian Oberleithner e Christian Oliver Paschereit. "NOx Emission Modelling for Lean Premixed Industrial Combustors With a Diffusion Pilot Burner". In ASME Turbo Expo 2021: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/gt2021-59071.

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Abstract In gas turbine combustion systems, the reduction of emissions of harmful combustion by-products is a main development goal. This study provides a methodology to model NOX emissions effectively for varying levels of pilot fuel flows at different operational points. It combines one-dimensional flame simulations using detailed chemistry with a stochastic approach for equivalence ratio fluctuations to account for the effect of fuel-air unmixedness. This split allows for computationally fast variations of the gas inlet condition and the consideration of different shares of pilot gas. The generation of emissions is split into a share of prompt formation at the flame front and a slower formation mechanism, occurring within the combustion products in the post flame region. The influence of unmixedness of the fuel-air mixture on both effects is taken into consideration by means of probability density functions (PDFs) of the equivalence ratio. These are modeled on the basis of sampled values from Large Eddy Simulations at the flame front and adapted for different shares of pilot gas. It is shown that with a superposition of Gaussian PDFs the equivalence ratio distribution at the flame front resulting from the main gas supply and the pilot share can be well approximated. Measurement data from experiments in atmospheric conditions as well as emission measurements from high pressure tests are used to evaluate the model. Good agreement is found for atmospheric data, allowing for explanations on the effect of pilot fuel ratio on emissions. For elevated pressure, only qualitative trends could be reproduced. Hypotheses to explain this deviation are made that motivate further research.

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Huang, Mingming, Zhedian Zhang, Weiwei Shao, Yan Xiong, Yan Liu, Fulin Lei e Yunhan Xiao. "Comparative Study of Syngas Mild Combustion Characteristics in Swirl Diffusion and Coflow Diffusion Staged Combustor". In ASME Turbo Expo 2013: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/gt2013-95349.

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MILD combustion is a promising combustion technology for the future gas turbine combustor due to its high combustion efficiency, low exhaust emissions and enhanced combustion stability. It utilizes the concept of exhaust gas recirculation to achieve combustion at reduced temperature and flat thermal field. To examine the role of gas recirculation level on MILD combustion performance, a laboratory-scale axially staged combustor constituted of gas generation zone, mixing zone and MILD combustion zone is presented. To realize ultra-low NOx emissions for syngas characterized by high flame temperature, it is necessary to select an appropriate combustion mode for the gas generation zone. This study compared combustion performance and gas/fuel/air mixing feature between two configurations, gas generation zone of which are based on swirl diffusion combustion and coflow diffusion combustion, respectively. The results are compared on flow field with numerical simulation, and global flame signatures and exhaust emissions with experiment. Both numerical simulation and experiment are performed at equivalence ratio of 0.4, heat load of 24.4 kW, using 10 MJ/Nm3 syngas as the fuel at atmospheric pressure and normal temperature fuel and air. More uniform oxidizer, lower flame temperature and less NOx production are observed in coflow diffusion staged combustion. MILD combustion zone is beneficial for the reduction of NOx and oxidation of CO exit from the gas generation zone.

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Newburry, Donald M., e Arthur M. Mellor. "Characteristic Time Model Correlation of NOx Emissions From Lean Premixed Combustors". In ASME 1995 International Gas Turbine and Aeroengine Congress and Exposition. American Society of Mechanical Engineers, 1995. http://dx.doi.org/10.1115/95-gt-135.

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The semi–empirical characteristic time model (CTM) has been used previously to correlate and predict emissions data from conventional diffusion flame, gas turbine combustors. The form of the model equation was derived for NOx emissions from laboratory flameholders and then extended to conventional gas turbine combustors. The model relates emissions to the characteristic times of distinct combustion subprocesses, with empirically determined model constants. In this paper, a new model is developed for lean premixed (LP) NOx emissions from a perforated plate flameholder combustor burning propane fuel. Several modifications to the diffusion flame CTM were required, including a new activation energy and a more complicated dependence on combustor pressure. Appropriate model constants were determined from the data, and the correlation results are reasonable. An attempt was made to validate the new model with LP NOx data for a different but geometrically similar flameholder operating at lower pressures. The predictions are good for the low equivalence ratio data. However, a systematic error in the reported equivalence ratios may be adversely affecting the predictions of the higher equivalence ratio data through the calculated adiabatic flame temperature.

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Relatórios de organizações sobre o assunto "Diffusion Equivalence"

Stafford, Paige L. Simulation of a field scale tritium tracer experiment in a fractured, weathered shale using discrete-fracture/matrix-diffusion and equivalent porous medium models. Office of Scientific and Technical Information (OSTI), maio de 1996. http://dx.doi.org/10.2172/219318.

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Kirchhoff, Helmut, e Ziv Reich. Protection of the photosynthetic apparatus during desiccation in resurrection plants. United States Department of Agriculture, fevereiro de 2014. http://dx.doi.org/10.32747/2014.7699861.bard.

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In this project, we studied the photosynthetic apparatus during dehydration and rehydration of the homoiochlorophyllous resurrection plant Craterostigmapumilum (retains most of the photosynthetic components during desiccation). Resurrection plants have the remarkable capability to withstand desiccation, being able to revive after prolonged severe water deficit in a few days upon rehydration. Homoiochlorophyllous resurrection plants are very efficient in protecting the photosynthetic machinery against damage by reactive oxygen production under drought. The main purpose of this BARD project was to unravel these largely unknown protection strategies for C. pumilum. In detail, the specific objectives were: (1) To determine the distribution and local organization of photosynthetic protein complexes and formation of inverted hexagonal phases within the thylakoid membranes at different dehydration/rehydration states. (2) To determine the 3D structure and characterize the geometry, topology, and mechanics of the thylakoid network at the different states. (3) Generation of molecular models for thylakoids at the different states and study the implications for diffusion within the thylakoid lumen. (4) Characterization of inter-system electron transport, quantum efficiencies, photosystem antenna sizes and distribution, NPQ, and photoinhibition at different hydration states. (5) Measuring the partition of photosynthetic reducing equivalents between the Calvin cycle, photorespiration, and the water-water cycle. At the beginning of the project, we decided to use C. pumilum instead of C. wilmsii because the former species was available from our collaborator Dr. Farrant. In addition to the original two dehydration states (40 relative water content=RWC and 5% RWC), we characterized a third state (15-20%) because some interesting changes occurs at this RWC. Furthermore, it was not possible to detect D1 protein levels by Western blot analysis because antibodies against other higher plants failed to detect D1 in C. pumilum. We developed growth conditions that allow reproducible generation of different dehydration and rehydration states for C. pumilum. Furthermore, advanced spectroscopy and microscopy for C. pumilum were established to obtain a detailed picture of structural and functional changes of the photosynthetic apparatus in different hydrated states. Main findings of our study are: 1. Anthocyan accumulation during desiccation alleviates the light pressure within the leaves (Fig. 1). 2. During desiccation, stomatal closure leads to drastic reductions in CO2 fixation and photorespiration. We could not identify alternative electron sinks as a solution to reduce ROS production. 3. On the supramolecular level, semicrystalline protein arrays were identified in thylakoid membranes in the desiccated state (see Fig. 3). On the electron transport level, a specific series of shut downs occur (summarized in Fig. 2). The main events include: Early shutdown of the ATPase activity, cessation of electron transport between cyt. bf complex and PSI (can reduce ROS formation at PSI); at higher dehydration levels uncoupling of LHCII from PSII and cessation of electron flow from PSII accompanied by crystal formation. The later could severe as a swift PSII reservoir during rehydration. The specific order of events in the course of dehydration and rehydration discovered in this project is indicative for regulated structural transitions specifically realized in resurrection plants. This detailed knowledge can serve as an interesting starting point for rationale genetic engineering of drought-tolerant crops.

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