11 research outputs found
Ein selbstgeschriebenes und komponiertes Kindermusical "Musig um d'Welt"
No full textIn den heutigen Schulklassen beobachtet man Folgendes: unterschiedliche Gruppierungen jeglicher Art. Unsere Praktika zeigten uns aber vor allem die Gruppierungen der Schweizer- und Migrantenkinder. Im Fach Musik jedoch, schienen diese Konstellationen nach unseren Erfahrungen weniger aufzutreten. Diesbezüglich entschieden wir uns, im Rahmen unserer Bachelorarbeit aufzuzeigen, wie Sozialintegration anhand eines schweizerdeutschen Musicals im Schulalltag geschehen kann.
Der literarische Teil basiert auf Erkenntnissen der Sozialintegration, Konzepten der Musikpädagogik und Kriterien des Lehrplans des Kantons St. Gallen. Unser Musical, welches auf eine dritte Klasse ausgerichtet ist, besteht aus schweizerdeutschen Liedern und Rollen mit integrativer Wirkung. Das Musical „Musig um d’ Welt“ bietet der Lehrperson neben zahlreichen, vielfältigen Musikerfahrungen eine hilfreiche Grundlage, Sozialintegration in der Klasse zu fördern
"RANIBIZUMAB NEL TRATTAMENTO DELLA DEGENERAZIONE MACULARE LEGATA ALL’ETÁ: DIAGNOSI E GESTIONE CLINICA E AMMINISTRATIVA DEL PAZIENTE" - DIAGNOSI E PROFILO DEL PAZIENTE CON AMD - ALGORITMO DI TRATTAMENTO E RITRATTAMENTO - PAZIENTI RESPONDER E NON RESPONDER - IL PROFILO DI SICUREZZA DI RANIBIZUMAB - LINEE GUIDA PER L’ESECUZIONE DI INIEZIONI INTRAVITREALI
No full textEsperti nel settore delle malattie retiniche in Lombardia si sono incontrati per discutere aspetti di interesse comune nell’AMD, sia sotto l’aspetto scientifico che amministrativo per proporre un consensus sulla diagnosi, trattamento e follow up del paziente affetto da AMD neovascolare in terapia con ranibizumab attraverso la revisione delle evidenze scientifiche in letteratura, della legislazione, delle indicazioni del Sistema Sanitario Nazionale (SSN) e soprattutto sulla base dell’esperienza clinica dei partecipanti. Advisory Board "Progetto Luce
Treatment of Retinal Angiomatous Proliferation with Intravitreal Anti-VEGF Drugs in Real Life Practice
No full textPurpose: To evaluate the outcomes of intravitreal anti-VEGF in the treatment of retinal angiomatous proliferation (RAP) in real life practice.
Methods: The design of the study is a retrospective, interventional, multicentre, case series. All the charts of patients affected by RAP, regularly followed up and treated with anti-VEGF drugs over 12 months were examined. All the patients underwent, both at baseline and over the follow-up, a monthly complete ophthalmologic examination, including best corrected visual acuity (BCVA) on ETDRS charts, fluorescein angiography, indocyanine green angiography, and ocular coherence tomography. Both intravitreal injections of ranibizumab and bevacizumab were considered for the study. After an initial loading phase of three consecutive injections, further re-treatments were administered on the basis of the identification of persistence or recurrence of subretinal/intraretinal fluid. The main outcome measure was the change in the mean BCVA at the 12-month examination. Secondary outomes included the proportion of eyes gaining at least 3 ETDRS lines, the mean change in the central retinal thickness (CRT), and number of injections at the end of the follow-up.
Results: Sixty-one eyes of 61 patients were considered for the study. Overall, the mean BCVA changed from 0.62, to 0.47 LogMAR (p: 0.004) at the 12-month examination. Seventeen eyes (28%) gained at least 3 ETDRS lines, whereas no eye lost more than 3 ETDRS lines, over the follow-up. Mean CRT passed from 333μm to 222μm (p < 0.001). Twenty-three eyes (37%) showed serous pigment epithelium detachment (PED) at baseline, which was still visible in 10 eyes (16%) at the end of the follow-up. No difference in BCVA gain was registered comparing ranibizumab and bevacizumab. Pigment epithelium detachment was detectable in 5% and 30% of the eyes, treated with ranibizumab and bevacizumab, respectively (p: 0.01). Mean number of injection was 4 and 4.6 in ranibizumab and bevacizumab subgroups, respectively.
Conclusions: Intravitreal anti-VEGF therapy can ensure a visual function improvement in about one third of patients affected by RAP, who are treated in the common clinical practice. Ranibizumab treatment requires less injections and more frequently leads to a pigment epithelium detachment resolution
Intravitreal Anti-VEGF Drugs for Retinal Angiomatous Proliferation in Real-Life Practice
No full textPURPOSE: To evaluate the outcomes of intravitreal anti-VEGF in the treatment of retinal angiomatous proliferation (RAP) in real life practice in seven Italian centers.
METHODS: Clinical data of 95 eyes of 95 patients affected by RAP, regularly followed up and treated with either intravitreal ranibizumab or bevacizumab over 12 months were examined. After a loading phase of three consecutive injections, re-treatments were administered on the basis of persistence or recurrence of subretinal/intraretinal fluid on OCT or leakage on FA.
RESULTS: Overall, the mean BCVA changed from 0.66 to 0.53 LogMAR (p: 0.0003): 36.8% of eyes gained at least 3 ETDRS lines, whereas 13.7% lost more than 3 lines at the end of the follow-up. Mean CRT improved from 384μm at baseline to 262μm at the 12-month examination (p<0.001). 68.4% of eyes showed serous pigment epithelium detachment (PED) at baseline, which was still visible in 30.5% at the end of follow-up. The mean number of injections was 4.4 over the follow-up. A significantly greater proportion of eyes showed resolution of PED when treated with ranibizumab (p<0.001).
CONCLUSIONS: Intravitreal anti-VEGF treatment in routine clinical practice allows a notable improvement in visual function in patients affected by RAP. A limited number of anti-VEGF injections are generally required in most cases
A Framework for Group Action-Based Multi-signatures and Applications to LESS, MEDS, and ALTEQ
No full textA multi-signature scheme allows a list of signers to sign a
common message. They are widely used in scenarios where the same
message must be signed and transmitted by .N users, and, instead of
concatenating .N individual signatures, employing a multi-signature can
reduce the data to be sent. In recent years there have been numerous
practical proposals in the discrete logarithm setting, such as MuSig2
(CRYPTO’21) for the Schnorr signature. Recently, these attempts have
been extended to post-quantum assumptions, with lattice-based proposals such as MuSig-L (CRYPTO’22). Given the growth of group actionbased signatures, a natural question is whether a multi-signature can be
built on the same models. In this work, we present the first construction
of such a primitive relying on group action assumptions. We obtain a 3-
round scheme achieving concurrent security in the ROM. Moreover, we
instantiate it using the three candidates to the additional post-quantum
NIST’s call, namely LESS, MEDS and ALTEQ, obtaining a good compression rate for different parameters set
Supplementary information about The PIONEER database
No full textData processing: Computed columns: By parsing the input data it is possible to increase the amount of columns in the database without changing the source format. The following columns are computed (or updated) in the back-end when the database is loaded from disk to memory.-- Assumptions for calculations:
A number of parameters are (re)calculated based on provided metadata for publications: the residence time (1), the SEI in J L-1 (2), energy efficiency of CO2 conv. % (5) but also the frequency range column (section 8.1).
Each of these calculations rely on data that potentially is given as a range of values, see section 1. By convention, the mean of the range is taken for each of the parameters. All entries for which a (re)calculation has been performed on either the x or y data, have the Calculated field set to ‘Calculated’ (rather than ‘Original’).
Filtering the database on only Original data, this calculated data can be replaced with calculations by the
user based on other aggregation, if desired.
As mentioned for equation (2), the calculation that converts power (in W) to SEI (J L-1) simply relies on
the gas flow rate Φ (in sccm or mLmin-1) and therefore does not take into account if Φ is defined w.r.t. standard
conditions or the actual conditions in the discharge regarding pressure and temperature. Since generally in this
case both the power and gas flux are know, the SEI can be calculated (except for batch reactors where there is
no flow), which allows for a comparison between a larger body of experiments.
Contrary to this, the calculations for the residence time (1) and energy efficiency of CO2 conversion both
take into account the discharge conditions. This discrepancy is a conscious one: the SEI (in J L-1) is often
reported as a macroscopic process parameter that is calculated from the power and fluxes put into the reactor.
For τ res taking into account the conditions inside the plasma is paramount, since it can provide the information
on how long a particle is exposed to plasma conditions. Do note that in lieu of the plasma –or active zone–
volume, for some experiments an approximation such as the reactor volume is used, see column relevant
volume in section 4.
Likewise for the efficiency, it is important to account for the actual measurement conditions to establish the
number of particles into which energy has been channelled. For in situ versus effluent conditions this can be very different. Overestimating the number density favourably improves efficiency, whilst an underestimation similarly negatively impacts it. While the way in which the PDB is structured and reports metadata is not without caveats (section 4.3 of the paper), the distinction between in- versus post-plasma dissociation measurements can be partially addressed by tailored filtering and aggregation of the data contained within.-- Normalisations:
Several normalisation functions are available in the interface of the database. As described in the main text, the aim to provide a tool for easy calculation of normalised data within the same interface and compare with different data sets. For flexibility sake, a wide set of normalisations are provided, without restriction on whether they are sensible in a given context. The purpose of each normalised function is described briefly and summarised in table 1 along with the equations utilised.-- Under a Creative Commons license CC BY 4.0.The Pioneer database (PDB) is divided into two parts: performance data and metadata. The performance data originate from measurements reported in literature, where they are typically provided in form of plots or
tables. The PDB and its dedicated online tool allow to compare large amounts of performance data to derive
trends leading eventually to process optimisation. Performance data is provided in form of plain text files with
only two comma-separated columns of numbers with a point (.) as decimal separator, without a header (as it
is inferred from the metadata). The first column contains what is henceforth called process parameters. These
are the independent variables of the experiments, i.e. the x-values like power, pressure etc., see section 7.
The second column contains the so-called performance parameters. These are the dependent variables of the
experiment, i.e. the y-values like conversion, selectivity etc., see section 7. The metadata contain additional
information about the measurements that are crucial for their interpretation. Metadata are provided in table
format following the template discussed subsequently.
Before elaborating on the actual data input, the structure of the PDB metadata is discussed. The metadata is
grouped thematically in categories. Within each category, information is entered into fields, i.e. the columns
of the table. Essential and conditional fields are distinguished. Essential fields contain crucial information for
the assessment of the plasma-catalytic process. In the best case scenario, all of them are given in the respective publication. When fields are listed in the description of a category from section 2 onward, essential fields are indicated by a regular bullet point (•). Conditional fields are by no means less important than essential ones, but can rather be left empty depending on other fields. For instance, most fields in the catalyst category are left empty, when no catalyst is used. Thus, conditional fields are meant to save time. Listed in the following,
they are indicated by a plus (+). In conclusion, all fields are strongly recommended as data useful for valuable
comparison with other work from the community. A subgroup of essential as well as conditional fields are those
fields that contain the process parameters defined in the first paragraph of this section. Generally speaking,
process parameters are the experimental settings in the pursuit of highest performance. The user of the PDB
thus encounters process parameters on two occasions: on the one hand as typical x-values in the performance
data and on the other hand as input to fields of the metadata. Hereafter, fields that contain process parameters
and parameters are used synonymously. The total of fields belonging to the same measurement make up what
is hereafter called a data set, corresponding to a row of the table. Note that here the input of data is addressed.
In the back end, a data set is broken up into (x,y)-pairs for more flexibility in data handling. Data is exported
also in that format.
To ensure comparability, a template is used for inputting information into the PDB metadata. With respect
to information entered, fields can be divided in numerical and textual fields. They are filled with numbers or
text, respectively. For example, parameters are usually numerical fields. A numerical field contains either (i)
one number x if the numerical value is known and does not change during the experiment; (ii) a range of values between xmin and xmax –given as array-like notation rxmin; xmaxs– if the numerical value is not exactly known, or when it changes in the course of the measurement; or (iii) NA if the numerical value is not known. For further use, an aggregate function is applied to array-like data to obtain a single number, by convention the mean.
A textual field contains a string of text. There are a few instances where text can be entered freely as long
as some format is followed. However, usually the field is filled by selecting from a pre-defined list of options
in the template. Most of these lists are fixed but some might be extended in the future depending on the
experimental data provided. This paragraph just gives a general overview. In the in-depth discussion of the
fields of each category, it gets more clear what exactly is supposed to be filled in each field. The metadata of the PDB are divided into six categories
• data identification
• gas mixture
• plasma source
• catalyst
• separation unit
• output data1. General
2. Data Identification
3. Gas Mixture
4. Plasma Source
5. Catalyst
5.1 Catalyst Coupling .
5.2 Catalyst Composition
5.3 Catalyst Pre-treatment Before Reaction
5.4 Catalyst Conditions
5.5 Catalyst Characterization
6. Separation Unit
7. Output Data
8. Data processing
8.1 Computed columns
8.2 Assumptions for calculations
8.3 NormalisationsWhen data is reported according to the specified scheme above, the combined data and metadata can be read
from disk and processed with some scripting. Most notably this performs data type coercion and extraction
from a more flexible ‘human-readable’ format to a consistent, ‘machine-usable’ scheme. Some of the computed columns are redundant to some extent –the authyear column for instance is just a concatenation of the first author name and publication year (yyyy) columns– but these are provided for ease of filtering or grouping data, avoiding frequent (re)computation.This project has received funding from the European Unions Horizon 2020 research and
innovation programme under the Marie Skodowska-Curie grant agreement No. 813393Peer reviewe
A Framework for Group Action-Based Multi-Signatures and Applications to LESS, MEDS, and ALTEQ
No full textA multi-signature scheme allows a list of signers to sign a common message. They are widely used in scenarios where the same message must be signed and transmitted by users, and, instead of concatenating individual signatures, employing a multi-signature can reduce the data to be sent.
In recent years there have been numerous practical proposals in the discrete logarithm setting, such as MuSig2 (CRYPTO\u2721) for the Schnorr signature. Recently, these attempts have been extended to post-quantum assumptions, with lattice-based proposals such as MuSig-L (CRYPTO\u2722).
Given the growth of group action-based signatures, a natural question is whether a multi-signature can be built on the same models. In this work, we present the first construction of such a primitive relying on group action assumptions. We obtain a 3-round scheme achieving concurrent security in the ROM.
Moreover, we instantiate it using the three candidates to the additional post-quantum NIST\u27s call, namely LESS, MEDS and ALTEQ, obtaining a good compression rate for different parameters sets
Mixing and evaporation of liquid droplets injected into an air stream flowing at all speeds
No full textThis paper deals with the formulation, implementation, and testing of three numerical techniques based on (i) a full multiphase approach, (ii) a multisize-group (MUSIG) approach, and (iii) a heterogeneous MUSIG (H-MUSIG) approach for the prediction of mixing and evaporation of liquid droplets injected into a stream of air. The numerical procedures are formulated following an Eulerian approach, within a pressure-based fully conservative finite volume method equally applicable in the subsonic, transonic, and supersonic regimes, for the discrete and continuous phases. The k-ε two-equation turbulence model is used to account for the droplet and gas turbulence with modifications to account for compressibility at high speeds. The performances of the various methods are compared by solving for two configurations involving streamwise and cross-stream sprayings into subsonic and supersonic streams. Results, which are displayed in the form of droplet velocity vectors, contour plots, and axial profiles, indicate that solutions obtained by the various techniques exhibit a similar behavior. Differences in values are relatively small with the largest being associated with droplet volume fractions and vapor mass fraction in the gas phase. This is attributed to the fact that with MUSIG and H-MUSIG, no droplet diameter equation is solved and the diameter of the various droplet phases is held constant, as opposed to the full multiphase approach. © 2008 American Institute of Physics.ABRAMZON B, 1989, INT J HEAT MASS TRAN, V32, P1605, DOI 10.1016-0017-9310(89)90043-4; AGGARWAL SK, 1995, J ENG GAS TURB POWER, V117, P453, DOI 10.1115-1.2814117; AGGARWAL SK, 1984, AIAA J, V22, P1448, DOI 10.2514-3.8802; Bertoli C, 1999, INT J HEAT FLUID FL, V20, P552, DOI 10.1016-S0142-727X(99)00044-2; BOGDANOFF DW, 1994, J PROPUL POWER, V10, P183, DOI 10.2514-3.23728; Brown DP, 2006, COMPUT FLUIDS, V35, P762, DOI 10.1016-j.compfluid.2006.01.012; Burger M, 2002, J ENG GAS TURB POWER, V124, P481, DOI 10.1115-1.1473153; CHEN XQ, 1995, NUMER HEAT TR A-APPL, V27, P143, DOI 10.1080-10407789508913693; Chen XQ, 1996, INT J HEAT MASS TRAN, V39, P441, DOI 10.1016-0017-9310(95)00162-3; Darwish M, 2001, NUMER HEAT TR B-FUND, V40, P99; FAETH GM, 1983, PROG ENERG COMBUST, V9, P1, DOI 10.1016-0360-1285(83)90005-9; Founti MA, 2007, NUMER HEAT TR B-FUND, V52, P51, DOI 10.1080-10407790701225496; Fox RO, 2008, J COMPUT PHYS, V227, P3058, DOI 10.1016-j.jcp.2007.10.028; Frossling N., 1938, Gerlands Beitrage zur Geophysik, V52; Gharaibah E, 2004, HEAT MASS TRANSF, P295; Godsave G.A.E., 1953, P 4 S INT COMB COMB, P818; GREENBERG JB, 1993, COMBUST FLAME, V93, P90, DOI 10.1016-0010-2180(93)90085-H; Hagessaether L., 2002, THESIS NORWEGIAN U S; HALLMANN M, 1995, J ENG GAS TURB POWER, V117, P112, DOI 10.1115-1.2812758; Hassanizadeh M, 1979, ADV WATER RESOUR, V2, P191, DOI 10.1016-0309-1708(79)90035-6; Hassanizadeh M, 1979, ADV WATER RESOUR, V2, P131, DOI 10.1016-0309-1708(79)90025-3; HUBBARD GL, 1975, INT J HEAT MASS TRAN, V18, P1003, DOI 10.1016-0017-9310(75)90217-3; JIN JD, 1985, COMBUSTION EMISSION, P213; Jones I., 2003, P 3 INT C CFD MIN PR, P13; KAY IW, 1992, J PROPUL POWER, V8, P507, DOI 10.2514-3.23505; Klose G, 2001, J ENG GAS TURB POWER, V123, P817, DOI 10.1115-1.1377010; KRAMER M, 1988, THESIS U KARLSRUHE; Krepper E, 2005, NUCL ENG DES, V235, P597, DOI 10.1016-j.nucengdes.2004.09.006; Launder B. E., 1974, Computer Methods in Applied Mechanics and Engineering, V3, DOI 10.1016-0045-7825(74)90029-2; LAURENT F, 2002, THESIS U CLAUDE BERN; Laurent F, 2004, J COMPUT PHYS, V194, P505, DOI 10.1016-j.jcp.2003.08.026; Luo H, 1996, AICHE J, V42, P1225, DOI 10.1002-aic.690420505; MASSOT M, 2003, THESIS U CLAUDE BERN; MELVILLE WK, 1979, INT J HEAT MASS TRAN, V22, P647, DOI 10.1016-0017-9310(79)90113-3; Miller RS, 1998, INT J MULTIPHAS FLOW, V24, P1025, DOI 10.1016-S0301-9322(98)00028-7; MOUKALLED F, 2003, P 12 IASTED INT C A, P1; Moukalled F, 2000, NUMER HEAT TR B-FUND, V37, P103; Patankar S. V., 1981, NUMERICAL HEAT TRANS; Pereira JCF, 1996, J HAZARD MATER, V46, P253, DOI 10.1016-0304-3894(95)00077-1; RAJASEKARAN A, 2006, 42 AIAA ASME SAE ASE; Sazhin SS, 2006, PROG ENERG COMBUST, V32, P162, DOI 10.1016-j.pecs.2005.11.001; Sazhin SS, 2005, INT J HEAT MASS TRAN, V48, P4215, DOI 10.1016-j.ijheatmasstransfer.2005.04.007; SHI JM, 2004, 2004 ANN REPORT I SA, P21; Sommerfeld M, 1998, INT J HEAT FLUID FL, V19, P10, DOI 10.1016-S0142-727X(97)10002-9; Spalding D.B., 1953, P 4 S INT COMB, P847; TALLEY DG, 1986, P 21 S INT COMB COMB, P609; TSOURIS C, 1994, AICHE J, V40, P395, DOI 10.1002-aic.690400303; Yeoh GH, 2004, CHEM ENG SCI, V59, P3125, DOI 10.1016-j.ces.2004.04.02322
The Least-Squares Spectral Element Method Solution of the Gas-Liquid Multi-fluid Model Coupled with the Population Balance Equation
No full textThis thesis work concentrates on the modelling of dispersed bubbly flow encountered widely in the chemical, oil & gas and nuclear industries. The computational fluid dynamics (CFD) that provides detailed information of gas-liquid flow has many advantages over the traditional modelling, which results in an enormously increased use of the CFD in the last decades. It has been found out that in order to describe the complex inhomogeneous behaviour of the gas-liquid flow caused by the size differences of bubbles, the necessary set of model equations to be solved must consist of the multi-fluid model for the flow, and a population balance equation (PBE) describing the bubble size distributions. Such a complex model leads to a very expensive computational load and thus requires an advanced, accurate and efficient method to enable an appropriate numerical solution. The least-squares spectral element method (LSSEM) which possesses many extraordinary numerical properties may be a very attractive method to deal with such a model. When solving the multi-fluid model the LSSEM has the potential of being much more accurate than the finite volume method (FVM) due to its higher order approximation. The pressure-velocity iterative algorithms like the semi-implicit pressure linked equation (SIMPLE) and the interphase slip algorithm (IPSA), are not required by the LSSEM. Furthermore, the properties of this method excludes the necessity of upwinded discretization of the convective terms. Being a PBE solver, the Gauss-Legendre-Lobatto (GLL) quadrature points used in the LSSEM ensures a more efficient discretization of the internal coordinate than the method of classes (CM). Unlike the Method Of Moments (MOM), the LSSEM provides a direct estimation of the number density function. The moments of any order can be retrieved by post-calculation, and the number of desired moments does not affect the number of transport equations to be solved. The least-squares formulation leads to a better conditioned system than the Quadrature Method Of Moments (QMOM), and it does not pose any stability problem. A new iterative algorithm is presented when using the LSSEM to couple the multi-fluid model and the PBE. It is based on the overall residue minimization so that the flow and the PBE are solved within same framework. The LSSEM also fully exploits the idea of single or multi-velocity group previously proposed in the homogeneous/inhomogeneous MUltiple-SIze-Group (MUSIG) models. The h/p-refinement divides the internal coordinate with high flexibility regarding to the size and velocity segregations. For many commonly used breakup kernels in physical problems, the conservation of volume/ mass is not always fulfilled, once they are employed in the CFD models. This unphysical feature is highly undesirable. In this work, the author propose a least-squares spectral element method which allows for incorporating the disperse phase mass-conservation (in the form of a continuity equation for the disperse phase) by means of the Lagrange multipliers method. The PBE is solved under this additional constraint by finding the saddle point of the coupled system. The results obtained by the constrained LSM show that the mass is conserved everywhere in the domain with high accuracy. The constrained LSM has significantly improved the performance of the nonconservative breakup kernels. A generic LSSEM toolbox lssem-suite has been designed and developed by the author. The lssem-suite toolbox is very flexible so that users can easily define the problem operator and other informations needed. The first bubble column model consisting of both flow equations and the PBE has been successfully solved by the LSSEM with the use of the lssem-suite. Interphase forces and breakage/coalescence kernels have been taken from the literature. The algorithm, coupling scheme as well as implementation are illustrated in the thesis. The resulting solution has been validated against experimental data obtained for two-phase flow in a bubble column. The predicted bubble size distribution and other flow quantities are in good agreement with the experimental data
The Least-Squares Spectral Element Method Solution of the Gas-Liquid Multi-fluid Model Coupled with the Population Balance Equation
No full textThis thesis work concentrates on the modelling of dispersed bubbly flow encountered widely in the chemical, oil & gas and nuclear industries. The computational fluid dynamics (CFD) that provides detailed information of gas-liquid flow has many advantages over the traditional modelling, which results in an enormously increased use of the CFD in the last decades.
It has been found out that in order to describe the complex inhomogeneous behaviour of the gas-liquid flow caused by the size differences of bubbles, the necessary set of model equations to be solved must consist of the multi-fluid model for the flow, and a population balance equation (PBE) describing the bubble size distributions.
Such a complex model leads to a very expensive computational load and thus requires an advanced, accurate and efficient method to enable an appropriate numerical solution. The least-squares spectral element method (LSSEM) which possesses many extraordinary numerical properties may be a very attractive method to deal with such a model.
When solving the multi-fluid model the LSSEM has the potential of being much more accurate than the finite volume method (FVM) due to its higher order approximation. The pressure-velocity iterative algorithms like the semi-implicit pressure linked equation (SIMPLE) and the interphase slip algorithm (IPSA), are not required by the LSSEM. Furthermore, the properties of this method excludes the necessity of upwinded discretization of the convective terms.
Being a PBE solver, the Gauss-Legendre-Lobatto (GLL) quadrature points used in the LSSEM ensures a more efficient discretization of the internal coordinate than the method of classes (CM). Unlike the Method Of Moments (MOM), the LSSEM provides a direct estimation of the number density function. The moments of any order can be retrieved by post-calculation, and the number of desired moments does not affect the number of transport equations to be solved. The least-squares formulation leads to a better conditioned system than the Quadrature Method Of Moments (QMOM), and it does not pose any stability problem.
A new iterative algorithm is presented when using the LSSEM to couple the multi-fluid model and the PBE. It is based on the overall residue minimization so that the flow and the PBE are solved within same framework. The LSSEM also fully exploits the idea of single or multi-velocity group previously proposed in the homogeneous/inhomogeneous MUltiple-SIze-Group (MUSIG) models. The h/p-refinement divides the internal coordinate with high flexibility regarding to the size and velocity segregations.
For many commonly used breakup kernels in physical problems, the conservation of volume/ mass is not always fulfilled, once they are employed in the CFD models. This unphysical feature is highly undesirable. In this work, the author propose a least-squares spectral element method which allows for incorporating the disperse phase mass-conservation (in the form of a continuity equation for the disperse phase) by means of the Lagrange multipliers method. The PBE is solved under this additional constraint by finding the saddle point of the coupled system. The results obtained by the constrained LSM show that the mass is conserved everywhere in the domain with high accuracy. The constrained LSM has significantly improved the performance of the nonconservative breakup kernels.
A generic LSSEM toolbox lssem-suite has been designed and developed by the author. The lssem-suite toolbox is very flexible so that users can easily define the problem operator and other informations needed.
The first bubble column model consisting of both flow equations and the PBE has been successfully solved by the LSSEM with the use of the lssem-suite. Interphase forces and breakage/coalescence kernels have been taken from the literature. The algorithm, coupling scheme as well as implementation are illustrated in the thesis. The resulting solution has been validated against experimental data obtained for two-phase flow in a bubble column. The predicted bubble size distribution and other flow quantities are in good agreement with the experimental data.PhD i kjemisk prosessteknologiPhD in Chemical Process Engineerin
