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Academic literature on the topic 'Semi-analytic models'

Author: Grafiati

Published: 1 April 2023

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Journal articles on the topic "Semi-analytic models"

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Lacerna, I., S. Contreras, R. E. González, N. Padilla, and V. Gonzalez-Perez. "Galactic conformity measured in semi-analytic models." Monthly Notices of the Royal Astronomical Society 475, no. 1 (December 20, 2017): 1177–89. http://dx.doi.org/10.1093/mnras/stx3253.

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Hartl, Urs T. "Semi-stable models for rigid-analytic spaces." manuscripta mathematica 110, no. 3 (March 2003): 365–80. http://dx.doi.org/10.1007/s00229-002-0349-x.

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Gruppioni, C., F. Calura, F. Pozzi, I. Delvecchio, S. Berta, G. De Lucia, F. Fontanot, et al. "Star formation inHerschel's Monsters versus semi-analytic models." Monthly Notices of the Royal Astronomical Society 451, no. 4 (June 25, 2015): 3419–26. http://dx.doi.org/10.1093/mnras/stv1204.

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Visbal, Eli, Zoltán Haiman, and Greg L. Bryan. "Self-consistent semi-analytic models of the first stars." Monthly Notices of the Royal Astronomical Society 475, no. 4 (January 17, 2018): 5246–56. http://dx.doi.org/10.1093/mnras/sty142.

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Donnelly, IJ, EK Rose, and JL Cook. "Magnetohydrodynamic Equilibrium Models for Rotamak Plasmas." Australian Journal of Physics 40, no. 2 (1987): 175. http://dx.doi.org/10.1071/ph870175.

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A semi-analytic method is used to solve the Grad-Shafranov equation for a range of compact torus plasma configurations which have ellipsoidal separatrices, zero toroidal magnetic field and pressure P proportional to the square of the poloidal flux function 1[1. The equilibria are compared with the analytic solutions of the Solov'ev model, for which P ex 1[1.

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Delfino, Facundo M., Claudia G. Scóccola, Sofía A. Cora, Cristian A. Vega-Martínez, and Ignacio D. Gargiulo. "Tracking the orbit of unresolved subhaloes for semi-analytic models." Monthly Notices of the Royal Astronomical Society 510, no. 2 (December 3, 2021): 2900–2919. http://dx.doi.org/10.1093/mnras/stab3494.

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ABSTRACT We present a model to track the orbital evolution of ‘unresolved subhaloes’ (USHs) in cosmological simulations. USHs are subhaloes that are no longer distinguished by halo finders as self-bound overdensities within their larger host system due to limited mass resolution. These subhaloes would host ‘orphan galaxies’ in semi-analytic models of galaxy formation and evolution (SAMs). Predicting the evolution of the phase-space components of USHs is crucial for the adequate modelling of environmental processes, interactions, and mergers implemented in SAMs that affect the baryonic properties of orphan satellites. Our model takes into account dynamical friction drag, mass-loss by tidal stripping and merger with the host halo, involving three free parameters. To calibrate this model, we consider two DM-only simulations of different mass resolution (MultiDark simulations). The simulation with higher mass resolution (smdpl; $m_{\rm DM} = 9.6 \times 10^7\, h^{-1}\, \mathrm{M_{\odot }}$) provides information about subhaloes that are not resolved in the lower mass resolution one (mdpl2; $m_{\rm DM} = 1.5 \times 10^9\, h^{-1}\, \mathrm{M_{\odot }}$); the orbit of those USHs is tracked by our model. We use as constraining functions the subhalo mass function (SHMF) and the two-point correlation function (2PCF) obtained from smdpl, being the latter a novel aspect of our approach. While the SHMF fails to put tight constraints on the efficiency of dynamical friction and the merger condition, the addition of clustering information helps us to specify the parameters of the model related to the spatial distribution of subhaloes. Our model allows to achieve good convergence between the results of simulations of different mass resolution, with a precision better than 10 per cent for both SHMF and 2PCF.

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Mitchell, Peter D., Cedric G. Lacey, Claudia D. P. Lagos, Carlos S. Frenk, Richard G. Bower, Shaun Cole, John C. Helly, Matthieu Schaller, Violeta Gonzalez-Perez, and Tom Theuns. "Comparing galaxy formation in semi-analytic models and hydrodynamical simulations." Monthly Notices of the Royal Astronomical Society 474, no. 1 (October 25, 2017): 492–521. http://dx.doi.org/10.1093/mnras/stx2770.

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Yates, Robert M., Bruno Henriques, Peter A. Thomas, Guinevere Kauffmann, Jonas Johansson, and Simon D. M. White. "Modelling element abundances in semi-analytic models of galaxy formation." Monthly Notices of the Royal Astronomical Society 435, no. 4 (September 9, 2013): 3500–3520. http://dx.doi.org/10.1093/mnras/stt1542.

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Henriques, Bruno M., Serena Bertone, and Peter A. Thomas. "The effect of dwarf galaxy disruption in semi-analytic models." Monthly Notices of the Royal Astronomical Society 383, no. 4 (December 21, 2007): 1649–54. http://dx.doi.org/10.1111/j.1365-2966.2007.12684.x.

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Brennan, Ryan, Viraj Pandya, Rachel S. Somerville, Guillermo Barro, Edward N. Taylor, Stijn Wuyts, Eric F. Bell, et al. "Quenching and morphological transformation in semi-analytic models and CANDELS." Monthly Notices of the Royal Astronomical Society 451, no. 3 (June 17, 2015): 2933–56. http://dx.doi.org/10.1093/mnras/stv1007.

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Dissertations / Theses on the topic "Semi-analytic models"

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Wang, Jie. "Simulating structure formation with N-Body and semi-analytic models." Diss., kostenfrei, 2008. http://edoc.ub.uni-muenchen.de/9184/.

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Yates, Robert M. "The chemical evolution of galaxies in semi-analytic models and observations." Diss., Ludwig-Maximilians-Universität München, 2014. http://nbn-resolving.de/urn:nbn:de:bvb:19-171119.

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The chemical compositions of the stars and gas in galaxies play a significant role in all their key evolutionary processes, from gas cooling, through star formation, to the production of new heavy elements that are released back into the gas as stars die in supernova explosions. A theoretical explanation of the production of elements heavier than helium (known simply as `metals' in astrophysics) in stars and its distribution throughout galaxies has been developing since the first postulation of stellar nucleosynthesis in the 1920s. However, there are still a number of unanswered questions in the field of galactic chemical evolution (GCE). For example, what is the most accurate way to measure the metallicities in galaxies? What are the relative contributions to GCE from different types of stars? How is this metal-rich material circulated throughout the various components of a galaxy? And how can we explain the seemingly incompatible chemical properties observed in different galaxies in the local Universe? This thesis provides an investigation into the chemical enrichment of galaxies, by utilising both observations of nearby galaxies and sophisticated GCE models within a semi-analytic model of galaxy evolution. Its core aims are a) to better quantify the chemical properties seen in low-redshift galaxies and explain there likely causes, and b) to develop an improved GCE model that can simultaneously reproduce the diverse chemical properties seen in different types of galaxies in the local Universe. With these aims in mind, Chapter 1 outlines the key background knowledge required for such an investigation. It discusses the different methods used for measuring the metallicity of real galaxies, and their various shortcomings. It also describes simple, analytic GCE models, and the sophisticated semi-analytic model, L-Galaxies, that is used to simulate galaxy evolution in detail. In Chapters 2 and 3, I provide an investigation into the relation between stellar mass (M*), star formation rate (SFR), and gas-phase metallicity (Zg) in galaxies. It is shown that the L-Galaxies model reproduces the positive correlation between SFR and Zg in massive galaxies that is seen when using sophisticated, theoretical metallicity diagnostics. This lends support to the use of such diagnostics over simpler, emission-line ratios. It is further shown that, in the semi-analytic model, this SFR-Zg correlation is due to the gradual dilution of the gas in low-SFR, elliptical galaxies, after a gas-rich merger event. A number of signatures of this particular evolution can be seen in these model galaxies at redshift zero, including low gas fractions and low values of (Zg-Z*). Crucially, all of these properties are also seen in nearby elliptical galaxies in the Sloan Digital Sky Survey (SDSS), providing indirect evidence that such an evolutionary process is also occurring in the elliptical galaxy population in the real Universe. In Chapter 4, I present a new, sophisticated GCE model implemented into L-Galaxies, that significantly improves on the previous scheme. It does this by accounting for the delayed enrichment of many chemical elements from stars, of various initial masses and metallicities, via stellar winds and supernovae. This new scheme enables a much more detailed study of the chemical evolution of galaxies, and enables a comparison with a larger range of observational data. In Chapter 5, I demonstrate that this new model is able to simultaneously reproduce the chemical properties observed in a) the gas of local, star-forming galaxies, b) the photospheres of G dwarfs in the Milky Way disc, and c) the integrated stellar populations of nearby elliptical galaxies. Furthermore, the model is able to do this without any significant deviation from the standard framework of galaxy formation in the canonical paradigm of hierarchical structure formation. This can be seen as a significant achievement, which has allowed us to form a much more comprehensive view of GCE than was possible before.
In den entscheidenden Entstehungsprozessen von Galaxien spielt die chemische Zusammensetzung von Sternen und Gas eine bedeutende Rolle: Von der Gaskühlung über die Sternentstehung bis hin zur Produktion neuer schwerer Elemente, die ins Gas zurückgegeben werden, wenn Sterne in Supernovae-Explosionen sterben. Eine theoretische Erklärung der Produktion von schwerer Elementen in Sternen sowie deren Verteilung in Galaxien wurde seit der ersten Erklärung der stellaren Nukleosynthese in den 1920ern entwickelt. Dennoch gibt es immer noch eine Reihe offener Fragen auf dem Gebiet der chemischen Galaxienentwicklung (galactic chemical evolution - GCE). Zum Beispiel: Was ist die genaueste Methode um die Metallizität von Galaxien zu messen? Welches sind die verhältnismäßigen Anteile der GCE bei unterschiedlichen Sternarten? Wie ist das metallreiche Material innerhalb der verschiedenen Teile einer Galaxie verteilt? Wie können wir die scheinbar inkompatiblen chemischen Eigenschaften erklären, die in verschiedenen Galaxien der kosmischen Nachbarschaft beobachtet werden? Diese Doktorarbeit untersucht die chemische Anreicherung von Galaxien in zweierlei Hinsicht: Es werden sowohl Beobachtungen naher Galaxien, als auch differenzierte GCE-Modelle im Rahmen eines semi-analytischen Galaxienentwicklungsmodells verwendet. Folgende Ziele hat die Arbeit: a) Sie soll die chemischen Eigenschaften von Galaxien mit niedriger Rotverschiebung quantifizierbar machen und mögliche Ursachen erklären. b) Es soll ein verbessertes GCE-Modell entwickelt werden, das die verschiedenen chemischen Eigenschaften abbildet, die in den Galaxien der kosmischen Nachbarschaft beobachtet werden können. Aufbauend auf dieser Zielsetzung wird in Kapitel 1 das nötige Hintergrundwissen erläutert, das für das Verständnis der Untersuchung wichtig ist. Dabei geht es um die verschiedenen Messmethoden zur Feststellung der Metallizität echter Galaxien sowie deren Schwächen. Neben einfachen analytischen GCE-Modellen werden auch die semi-analytischen Modelle, L-Galaxies beschrieben. In den Kapiteln 2 und 3 erläutere ich den Zusammenhang von stellar mass (M*), star formation rate (SFR) und der gas-phase metallicity (Zg) in Galaxien. Es zeigt sich, dass das L-Galaxies-Modell den positiven Zusammenhang zwischen SFR und Zg in massiven Galaxien abbildet. Dieser wird auch deutlich, wenn theoretische Metallizitätsdiagnosen zur Anwendung kommen statt einfacherer Diagnosen. Außerdem wird gezeigt, dass im semi-analytischen Modell die Wechselwirkung von SFR-Zg auf eine allmähliche Verdünnung des Gas in elliptischen Galaxien zurückzuführen ist, die nach dem Verschmelzen zweier gas-reicher Galaxien SFR-arm sind. Einige Merkmale dieser besonderen Entstehung, wie beispielsweise eine niedrige Gasfraktion und niedrige (Zg-Z*), können auch in den besagten Modellgalaxien gesehen werden. Entscheidend ist außerdem, dass all diese Eigenschaften auch im Rahmen der Sloan Digital Sky Survey (SDSS) in nahe gelegenen elliptischen Galaxien beobachtet werden. Das ist ein indirekter Beweis dafür, dass es diese Art von evolutionärem Entstehungsprozess tatsächlich in den elliptischen Galaxien unseres Universums gibt. In Kapitel 4 stelle ich ein neues, differenziertes GCE-Modell vor, das in L-Galaxies implementiert wurde. Es ist besser als sein Vorgänger, da es die durch Sternenwinde und Supernoven verzögerte Anreicherung vieler chemischer Elemente von verschiedenen Sternen berücksichtigt. Das neue Modell erlaubt also zum einen eine detailliertere Betrachtung der chemischen Entstehung von Galaxien und zum anderen macht es den Vergleich einer größeren Bandbreite von Beobachtungsdaten möglich. In Kapitel 5 erläutere ich schließlich, dass das neue Modell gleichzeitig die chemischen Eigenschaften reproduzieren kann, die an folgenden Stellen beobachtet werden: a) im Gas lokaler, sternbildender Galaxien. b) in den Photosphären von G-Zwergen auf der Milchstraßen . c) den integrierten Sternenpopulationen elliptischer Galaxien in der Nachbarschaft. Hinzu kommt, dass es das Modell ermöglicht, all dies zu tun, ohne dabei vom Standardrahmen abzuweichen, den unser kanonisches Verständnis der Galaxienentwicklung bildet. Diese bedeutende Errungenschaft macht es uns jetzt möglich, GCE in einem wesentlich umfassenderen Rahmen zu betrachten.

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Clay, Scott Jonathan. "The formation and evolution of dust in semi-analytic models of galaxy formation." Thesis, University of Sussex, 2017. http://sro.sussex.ac.uk/id/eprint/70546/.

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The formation and evolution of galaxies is an interesting subject to study because it incorporates astrophysics from all scales, from the initial perturbations in the early universe creating the large scale structures that produce galaxies, right down to the evolution of stellar populations and their manipulation of the host galaxy. Simulations of galaxy formation allow us to test the various physical recipes against that which is observed in order to build a true and proper picture of what is happening in the real universe. L-Galaxies is a semi-analytic model of galaxy formation built on top of the merger trees from the Millennium dark matter simulation, and is constrained to match certain key observations at low redshift by applying a Monte Carlo Markov Chain (MCMC) method to constrain the free parameters. In using the model to make high redshift predictions of the stellar mass function, UV luminosity function and star formation rate distribution function we found that the model starts to deviate from observational constraints at the highest redshifts, particularly in high mass galaxies. In the case of the UV luminosity function, this is because the current dust model is calibrated at low redshift and lacks sophistication in that it only depends on the cold gas mass and the density of metals. To improve on this we implement a physically motivated dust model that traces the formation of dust from stellar sources, such as in the stellar winds of AGB stars and in the supernovae remnants of massive stars, the growth of dust inside molecular clouds, and the destruction of dust due to supernovae explosions. The model is fully integrated into L-Galaxies such that the evolution of dust is included in all the recipes relevant to the formation and evolution of galaxies, including: star formation; radiative feedback; cooling and reheating; and both major and minor mergers. Our results show a good fit to observations of the dust mass in galaxies both in the local universe and out to high redshift and we note a similar conclusion as in the literature that dust growth inside molecular clouds is not only necessary but the dominant source of the dust mass in these galaxies. However, stellar sources of dust can not be neglected as molecular clouds must first be seeded by dust grains in order for accretion to occur. This could be important in the very early universe, perhaps for the first galaxies that will hopefully be observed by JWST in the future, because these galaxies may not have had sufficient time to seed their molecular clouds and as such the dust produced by these stellar sources would be important for calculating the galaxies true observed luminosity. We finish by discussing the limitations of the model and discuss areas for possible improvement as well as the next steps in using this to better predict the luminosity of galaxies in future models.

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Yates, Robert M. [Verfasser], and Simon [Akademischer Betreuer] White. "The chemical evolution of galaxies in semi-analytic models and observations / Robert M. Yates. Betreuer: Simon White." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2014. http://d-nb.info/1056876344/34.

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Saghiha, Hananeh [Verfasser]. "Comparing galaxy-galaxy(-galaxy) lensing in semi-analytic models and observations to study galaxy evolution / Hananeh Saghiha." Bonn : Universitäts- und Landesbibliothek Bonn, 2017. http://d-nb.info/113070467X/34.

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Henriques, Bruno M. "Hybrid galaxy evolution modelling : Monte Carlo Markov Chain parameter estimation in semi-analytic models of galaxy formation." Thesis, University of Sussex, 2010. http://sro.sussex.ac.uk/id/eprint/2334/.

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We introduce a statistical exploration of the parameter space of the Munich semi-analytic model built upon the Millennium dark matter simulation. This is achieved by applying a Monte Carlo Markov Chain (MCMC) method to constrain the 6 free parameters that define the stellar mass function at redshift zero. The model is tested against three different observational data sets, including the galaxy K-band luminosity function, B −V colours, and the black hole-bulge mass relation, to obtain mean values, confidence limits and likelihood contours for the best fit model. We discuss how the model parameters affect each galaxy property and find that there are strong correlations between them. We analyze to what extent these are simply reflections of the observational constraints, or whether they can lead to improved understanding of the physics of galaxy formation. When all the observations are combined, the need to suppress dwarf galaxies requires the strength of the supernova feedback to be significantly higher in our best-fit solution than in previous work. We interpret this fact as an indication of the need to improve the treatment of low mass objects. As a possible solution, we introduce the process of satellite disruption, caused by tidal forces exerted by central galaxies on their merging companions. We apply similar MCMC sampling techniques to the new model, which allows us to discuss the impact of disruption on the basic physics of the model. The new best fit model has a likelihood four times better than before, reproducing reasonably all the observational constraints, as well as the metallicity of galaxies and predicting intra-cluster light. We interpret this as an indication of the need to include the new recipe. We point out the remaining limitations of the semi-analytic model and discuss possible improvements that might increase its predictive power in the future.

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McCord, Krista. "Coupling Semi-Analytic Models and N-Body Simulations| A New Way of Making Galaxies and Stellar Halos." Thesis, The University of Alabama, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10240760.

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Stellar halos give insight into the initial conditions that existed when a host galaxy first formed and provide details on disrupted satellites via their different stellar populations. An algorithm that is computationally inexpensive compared to hydrodynamic simulations is necessary in order to theoretically study the structure and formation of galactic stellar halos in sufficient detail to probe substructure. CoSANG (Coupling Semi-Analytic/N-body Galaxies) is a new computational method that we are developing which couples pure dark matter N-body simulations with a semi-analytic galaxy formation model. At each timestep, results from the N-body simulation feed into the semi-analytic code, whose results feed back into the N-body code making the evolution of the dark matter and baryonic matter dependent on one another. CoSANG will enable a variety of galaxy formation science, including analysis of stellar populations, halo merging, satellite accretion, supermassive black holes, and indirect and direct dark matter detection.

In this dissertation, I will describe the new simulation code CoSANG. The results from the extensive testing phase on CoSANG will be presented which indicate CoSANG is properly simulating feedback from galaxies within a dark matter halo. I used this validated code to analyze a CoSANG zoom simulation of a 10¹²M solar masses dark matter halo. Results showed a flatter inner halo near the disk and a more spherical outer halo which is expected when a galaxy exists at the center of a dark matter halo. A comparison is made with a simulation run with the same initial conditions, but with the baryonic component simulated using a hydrodynamic algorithm. The semi-analytic model predicted galaxy types better than the hydrodynamic simulation leading to the conclusion that the CoSANG halo is more accurate. I also present a dark matter direct detection analysis on the CoSANG zoom halo to measure the dark matter velocity distributions and modulation amplitudes. The CoSANG results show that the dark matter velocity distribution does not fit well to a Maxwell Boltzmann distribution and the modulation amplitudes derived indicate an anisotropic dark matter velocity distribution. Future work will include tagging dark matter particles with stellar properties to build and evolve a stellar halo.

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Murphy, Geoff. "Stellar Halos: modelling formation in the L-Galaxies 2020 semi-analytic model." Master's thesis, Faculty of Science, 2020. http://hdl.handle.net/11427/32850.

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A study was carried out to determine how well the L-Galaxies 2020 semi-analytic model simulates the stellar halos of galaxies and the intracluster stellar (ICS) components of galaxy clusters. Two galaxy disruption models were tested, namely instantaneous disruption and gradual disruption. Furthermore, two stellar halo profiles were applied to the simulation results: a power-law profile with slope γ = −3.5 and a Navarro-Frenk-White (NFW) profile. In the latter case, the stellar halo stars follow the distribution of the galaxy's dark matter. It was found that a combination of an NFW profile and gradual disruption provided the best results across the widest range of literature data, namely measurements of stellar halo mass, total stellar mass, stellar mass fractions, and stellar halo iron abundances. Gradual disruption of satellite galaxies also resulted in the central galaxies having more massive stellar halos in comparison to instantaneous disruption. Additional stellar halo formation mechanisms, such as in-situ star formation, were not needed, as the stellar halo masses seen in observations can be obtained in L-Galaxies by considering only tidal disruption of infalling satellite galaxies. The number of high mass accretions into the halos of Milky Way-mass galaxies in the gradual disruption model agreed well with simulation literature. It was found that while central galaxies can induce many disruptions of satellite galaxies (over a thousand in some cases), the majority of the Milky Way-sized stellar halos in L-Galaxies are formed by the disruption of one to fourteen satellite galaxies, in good agreement with simulation literature. A population of galaxies with unexpectedly low stellar halo iron abundances was found. These were determined to be a result of disruptions of high mass, low metallicity satellite galaxies. Furthermore, rather than iron or oxygen, carbon was found to be the dominant element produced by stellar halo stars for the majority of redshifts in most high mass central and satellite galaxies, due mainly to asymptotic giant branch stars. The relative contribution of stellar halo stars was found to be minor, however, with circumgalactic medium enrichment from halo stars in comparison to outflows from galactic stars being on average . 1%. For clusters with virial masses exceeding 1.6 × 1014M, the brightest central galaxy and ICS (BCG+ICS) stars contained 42.44% of the total cluster stellar iron content, while the fraction MICS MBCG+MICS was found to be 82.50%, both results being in good agreement with observation.

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Srisawat, Chaichalit. "Semi-analytic model of galaxy formation with radiative feedback during the Epoch of Reionisation." Thesis, University of Sussex, 2016. http://sro.sussex.ac.uk/id/eprint/65583/.

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Several hundred million years after the Big Bang, the Epoch of Reionisation(EoR) started as the photons from the first objects ionised neutral baryons in the Universe. The observations such as the Gunn-Peterson troughs in quasar absorption spectra and the linear polarisation of the cosmic microwave background (CMB) impose strong constraints on reionisation models of the EoR. Recent data provide the rest-frame ultraviolet luminosity of galaxies up to redshift 10. However, the observation of star formations in low mass galaxies is still not practicable. Their star formations are expected to be suppressed by the increase of ionised baryons and greatly affect the reionisation models. We develop a flexible pipeline which utilises the Munich Semi-Analytic Model of galaxy formation, L-Galaxies, and a semi-numerical modelling of cosmic reionisation. This combination allows us to create a self-consistent reionisation simulation in computational models of galaxy formation. We use this pipeline on a high resolution cosmological Nbody simulation to produce the redshift evolution of the star forming galaxies during the EoR. Comparisons of the properties of mock galaxies and the growth of ionised hydrogen bubbles suggest that the reionisation history heavily depends on the suppression models used in the modeling of dwarf galaxy formation. During this research, some numerical flaws of merger tree generation algorithms were identified. We investigated the origins of these problems and present suggestions for solving them.

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Shamshiri, Sorour. "Predictions for the infrared numbercounts and star formation histories from a semi-analytic model of galaxy formation." Thesis, University of Sussex, 2017. http://sro.sussex.ac.uk/id/eprint/69945/.

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One of the most fundamental probes of the physics that underpins galaxy evolution is the star formation rate (SFR) as a function of cosmic time. In addition, the statistical prop- erties of galaxy populations are another important key to understand how the universe has been evolving. It is known that the far-infrared emission from galaxies is strongly correlated with obscured star formation and forms a significant part of cosmic infrared background. We thus investigate the variation of the SFR of galaxies over time by com- paring predictions of the L-Galaxies semi-analytic model with observations of the far infrared (FIR) luminosity and number counts. In the first part of this thesis, we follow the star formation histories (SFHs) of galaxies and use these to construct stellar spectra in post-processing. We then contrast model SFHs from the Millennium Simulation with observed ones from the VESPA algorithm as applied to the SDSS-7 catalogue when this has been characterized by mass and colour of galaxies. In order to investigate the SAM model prediction, I extend L-galaxies to predict far infrared fluxes and construct mock catalogues which are fed into SMAP in order to provide simulated maps. LFs have also been estimated for model galaxies at different redshifts. The results are compared with observations from Herschel. To conclude, our model under- estimates the number density of galaxies at bright sources (e.g fluxes above 0.02 Jy) also does not produce high luminosity objects especially at higher redshifts (e.g z > 1) . We show that by fitting the simulated IR luminosity function to observed LIR, our model is able to produce more bright sources at high redshifts and match reasonably well to the observed number counts.

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Books on the topic "Semi-analytic models"

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Banasiak, Jacek, Wilson Lamb, and Philippe Laurencot. Analytic Methods for Coagulation-Fragmentation Models, Volume II. Taylor & Francis Group, 2019.

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Banasiak, Jacek, Wilson Lamb, and Philippe Laurencot. Analytic Methods for Coagulation-Fragmentation Models, Volume II. Taylor & Francis Group, 2019.

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Banasiak, Jacek, Wilson Lamb, and Philippe Laurencot. Analytic Methods for Coagulation-Fragmentation Models, Volume II. Taylor & Francis Group, 2019.

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Book chapters on the topic "Semi-analytic models"

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Devriendt, Julien E. G., Bruno Guiderdoni, and Shiv K. Sethi. "Semi-Analytic Models and Background Hydrogen-Ionizing Flux." In Looking Deep in the Southern Sky, 301–2. Berlin, Heidelberg: Springer Berlin Heidelberg, 1999. http://dx.doi.org/10.1007/978-3-540-49460-7_56.

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Lu, Yu, H. J. Mo, Martin D. Weinberg, and Neal Katz. "Bayesian Predictions from the Semi-analytic Models of Galaxy Formation." In Lecture Notes in Statistics, 523–25. New York, NY: Springer New York, 2012. http://dx.doi.org/10.1007/978-1-4614-3520-4_58.

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Lu, Xingjie, and Jianyang Xia. "Semi-Analytic Spin-Up (SASU) of Coupled Carbon-Nitrogen Cycle Models." In Land Carbon Cycle Modeling, 115–21. Boca Raton: CRC Press, 2022. http://dx.doi.org/10.1201/9780429155659-18.

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"Galaxy Evolution and Semi-analytic Models." In Large-Scale Peculiar Motions, 35–51. WORLD SCIENTIFIC, 2021. http://dx.doi.org/10.1142/9789811211812_0004.

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Chen, Chun-Hung, Hing-Tong Cho, and Alan S. Cornell. "Semi-Analytic Techniques for Solving Quasi-Normal Modes." In Trends in Modern Cosmology. InTech, 2017. http://dx.doi.org/10.5772/68114.

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Kantorovitz, Shmuel, and Ami Viselter. "Integral representation." In Introduction to Modern Analysis, 253–88. 2nd ed. Oxford University PressOxford, 2022. http://dx.doi.org/10.1093/oso/9780192849540.003.0009.

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Abstract This chapter is mostly concerned with integral representations of bounded operators, which are far-reaching generalizations of the spectral theorem for selfadjoint matrices. We prove the classical spectral theorem for normal operators on Hilbert spaces. We then use a renorming method in the general Banach space setting to construct the semi-simplicity space of a bounded operator, on which it admits a continuous operational calculus provided that the Banach space is reflexive. We present the analytic operational calculus for elements of an arbitrary Banach algebra and use it to develop the Riesz–Schauder theory of compact operators. Finally, the chapter offer exercises to challenge the reader.

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Guo, Jie, Shahrokh Nikou, and Harry Bouwman. "Business Model for Mobile Payment in China." In Sustainable Business, 268–93. IGI Global, 2020. http://dx.doi.org/10.4018/978-1-5225-9615-8.ch013.

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Despite the predicted success of mobile payment, the market remains immature in most countries. Major concerns are the relationship between push and pull technologies, and the role of platforms, service innovation, power and control in ecosystems. As the first step in their mixed-method research approach, using Analytic Hierarchy Process (AHP) as a research approach and the STOF business model as a research framework, the authors aim to identify design issues for m-payment services from mobile network operators' perspectives. Furthermore, the authors compare insights from semi-structured interviews with experts in the field to the empirical findings, to assess how the actual business model of Chinese m-payment services can be improved based on design issues derived from the business model. The results show that components such as building customer trust on payment services, innovative payment experience, and extend market to new segments, guarantee security and privacy issues, user profile management, and hardware problems involving existing infrastructure, customer/merchant relationship, platform interoperability, and cost saving on fraud detection need to be improved to enhance the potential of m-payment, supported by a viable and sustainable business model. There is also a role for policy and regulation to be played.

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Conference papers on the topic "Semi-analytic models"

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Maller, Ariyeh H., Rachel S. Somerville, Jason X. Prochaska, and Joel R. Primack. "Making damped Lyman-α systems in semi-analytic models." In AFTER THE DARK AGES. ASCE, 1999. http://dx.doi.org/10.1063/1.58642.

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Fu, Jian, Qi Guo, Guinevere Kauffmann, Victor P. Debattista, and C. C. Popescu. "Semi-Analytic Models on the Molecular and Neutral Gas in Galaxies." In HUNTING FOR THE DARK: THE HIDDEN SIDE OF GALAXY FORMATION. AIP, 2010. http://dx.doi.org/10.1063/1.3458474.

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Lovell, M. R., S. Bose, A. Boyarsky, S. Cole, C. Frenk, V. Gonzalez-Perez, R. Kennedy, O. Ruchayskiy, and A. Smith. "Galaxy formation in semi-analytic models with sterile neutrino dark matter." In Proceedings of the MG14 Meeting on General Relativity. WORLD SCIENTIFIC, 2017. http://dx.doi.org/10.1142/9789813226609_0287.

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McCain, Buz A., Anna G. Stefanopoulou, and Kenneth R. Butts. "On Controllability and Observability of Linearized Liquid Water Distributions Inside a PEM Fuel Cell." In ASME 2008 Dynamic Systems and Control Conference. ASMEDC, 2008. http://dx.doi.org/10.1115/dscc2008-2155.

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We analyze the controllability and observability (C/O) of first principles-based numeric and reduced semi-analytic PEMFC models, with emphasis on the effects of model reduction on these analyses. The numeric model is a partial differential equation (PDE) based model approximated by difference equations, including both channels and both GDL of a PEMFC. The reduced model uses a semi-analytic solution (SAS) method, which is a combination of analytic and numeric solutions, gaining physical intuition at lower computational cost. The C/O analysis is based on linearizations around multiple operating points of the numeric and the semi-analytic models. The results indicate that stabilizability of the anode water states is possible.

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Luo, Heng, Yun Li, and Hai Wang. "A Universal Semi-Analytic Model for Axial Mixing in a Straight Pipe." In ASME 2014 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/imece2014-37351.

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The industrial applications of common pipelines to simultaneously deliver multiple types of gases or liquids widely occur in petroleum and natural gas industries. Therein, the pipelines compose of significant horizontal and vertical sections can range from several meters to several km in length. The longitudinal dispersion of matter is an important aspect of such flows in safety and reliability. This paper sets out an analytic simulation model on the basis of the profiles of velocity and turbulent viscosity via steady numerical solutions by computational fluid dynamics (CFD) method. The mixing length and the wasting lengths of the original and latter fluids were applied as the key parameter to describe the extent of axial mixing in the pipe. In both turbulent and laminar pipe flows, the relative errors in the present model were reduced to 5% or less, which is 5%–15% lower than those in previous models. Moreover, the accuracy of the present model was nearly not less than that of unsteady numerical solutions in the same meshing density, whereas the computational load of the present model was far less than that of unsteady numerical solutions. Further, through investigating effects of buoyancy on axial mixing, it is found that the wasting length of the lighter fluid was higher than that of the heavier fluid.

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Short, C. J., P. A. Thomas, Sebastian Heinz, and Eric Wilcots. "Combining Semi-Analytic Models of Galaxy Formation with Simulations of Galaxy Clusters: the Need for AGN Heating." In THE MONSTER’S FIERY BREATH: FEEDBACK IN GALAXIES, GROUPS, AND CLUSTERS. AIP, 2009. http://dx.doi.org/10.1063/1.3293097.

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Park, Hyunjae, Nicholas Nigro, Neil Gollhardt, and Ping Lee. "Development and Integration of a Semi-Analytical PCB Thermal Design Technique With an Infrared Thermal Imaging System." In ASME 2001 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/imece2001/aes-23600.

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Abstract Traditionally, analytical models are developed to predict the thermal behavior of Printed Circuit Boards (PCBs). The predicted results are then verified with other analytical or experimental results prior to using the models in design. This is a time intensive process and the results predicted using these models may include limitation due to idealization. In order to overcome this disadvantage, a semi-analytical model is proposed in this study. The semi-analytical model uses analytic theory in conjunction with results obtained from an Infrared-Radiation Thermal Imaging System (IRTIS). The model is verified and updated, allowing the results to be immediately incorporated into PCB thermal design. The parameters in the semi-analytical model are determined by employing a least squares temperature curve fit for the first upstream heating component in conjunction with a simple conduction model for the PCB wall. The model was tested with a natural convection cooled PCB with three inline heating components. Temperature data for the first upstream component was measured with an IRTIS and fit to the semi-analytical model. The model predicted temperature results for all three heating components with good agreement. The PCB thermal design technique enables the IRTIS to be employed as a preliminary design tool that significantly reduces design iterations through the use of the semi-analytical model.

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Rezanejad, Kourosh, Joydip Bhattacharjee, and C. Guedes Soares. "Analytical and Numerical Study of Nearshore Multiple Oscillating Water Columns." In ASME 2013 32nd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/omae2013-11513.

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In the present study, the performance of two chamber nearshore oscillating water columns (OWCs) in finite water depth is analyzed based on the linearized water wave theory in the two dimensional Cartesian coordinate systems. The barriers are assumed to be fixed and the turbine characteristics are assumed linear with respect to the fluctuations of volume flux and pressure inside the chamber. The free surface inside the chambers is modeled as a non-plane wave surface. Two different mathematical models are employed to solve the hydrodynamic problem; the semi-analytic method of matched eigenfunction expansion and the numerical scheme of Boundary Integral Equation Method (BIEM). The numerical results are compared with the semi-analytic results and show good agreement. The effects of the distance between the barriers and the length of the barriers on the efficiency of the OWC device are investigated. The results of two chambers OWC are also compared with the results for an equivalent single OWC chamber. Further, the effect of the water depth on the capacity of the wave power absorption is discussed.

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Ghasemi, Amirmahdi, Mohammad Moghiman, Seyed Mohammad Javadi, and Naseh Hosseini. "Effects of Droplet Size and Air Preheating on Soot Formation in Turbulent Combustion of Liquid Fuel." In ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2010. http://dx.doi.org/10.1115/esda2010-24663.

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The present study is concerned with the effect of fuel droplet size, air inlet preheating and air swirl number on complex soot process in a turbulent liquid-fuelled combustor. A hybrid Eulerian-Lagrangian method is employed to model the reactive flow-field inside the combustor. Equations governing the gas phase are solved by a control volume based semi-implicit iterative procedure while the time-dependent differential equations for each sizes of the fuel droplets are integrated by a semi-analytic method. The processes leading to soot consist of both formation and combustion. Soot formation is simulated using a two-step model while a finite rate combustion model with eddy dissipation concept is implemented for soot combustion. Also, mathematical models for turbulence, combustion, and radiation are used to take account the effects of these processes. Results reveal the significant influence of liquid fuel droplet size, air inlet temperatures and swirl numbers on soot emission from turbulent spray flames. The predictions show that reduction of spray droplet size and increases of air inlet temperature and swirl numbers considerably, increases soot emission from spray flames.

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Kim, Jang Whan, Hyunchul Jang, Seongmo Yeon, and Hyunjoe Kim. "Numerical Modeling of Sustainable Atmospheric Boundary Layer for Offshore Floaters." In ASME 2021 40th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/omae2021-63807.

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Abstract Wind load is one of the major design load considerations for the hull and mooring of offshore floating facilities. The first step to minimize the uncertainties in wind load is generating an accurate wind profile that satisfies design requirements. Recently, there was a joint-industry effort to develop CFD modeling practices on wind-load estimation in SNAME OC-8 CFD Task Force (OMAE2018-78699). The Task Force developed the modeling practice for the NPD (Norwegian Petroleum Directorate) model commonly used for offshore platform design, and several independent participants in the Task Force successfully validated the practice for a topsides of a semi-submersible platform. The sustainable wind profile was able to be generated within 1% tolerance of the target wind profile, and the calculated wind loads on the topsides from CFD simulations were close to the model test data with low uncertainty levels. In the present study, the numerical modeling for the sustainable ABL is extended to other popular wind models such as the ESDU (Engineering Science Data Unit) and the power-law models. The study is a part of a joint-development project between TechnipFMC, Chevron, and Samsung Heavy Industries. The analytic or numerical formulae of wind speed and turbulent quantities for several RANS (Reynolds-Averaged Navier-Stokes) models are derived for the wind models, and the sustainability of wind profiles are verified.

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