Data Science, Digital Transformation, Risks & Complex Systems

@article{bignoumba_2463,

title = {A new efficient ALignment-driven Neural Network for Mortality Prediction from Irregular Multivariate Time Series data},

author = {Nzamba Bignoumba and Nédra Mellouli and Sadok Ben Yahia},

url = {https://www.sciencedirect.com/science/article/pii/S0957417423026507?via%3Dihub},

year  = {2024},

date = {2024-03-01},

journal = {Expert Systems With Applications},

volume = {238},

number = {Part E},

pages = {122148},

abstract = {The irregularity of the time interval between observations in and across the stream is a key factor that leads to a drop in performance when classical machine learning or deep learning models are used for a downstream task requiring multivariate time series. Indeed, irregular multivariate time series not only increase the rate of missing values but also lead to data sparsity, which consequently makes the data almost unleverageable and/or ineffective for models. To tackle this scorching challenge, most of the pioneering approaches apply imputation or interpolation in their core, which might lead to embedding data with noise. To especially address this irregular multivariate time series issue, we introduce, in this paper, a new deep neural network model called ALignment-driven Neural Network. The innovative idea of our model is to transform the irregular multivariate time series into pseudo-aligned (or pseudo-regular) latent values. The latter are shown as a matrix, where the coefficients are the latent values of each feature at user-defined reference time points that are evenly spaced. They are obtained through a duplication process driven by an exponential decay mechanism. The obtained output is then passed to a Recurrent Neural Network model, which is undoubtedly the must-use model for regular time series data. To show that our model added value, we looked at the Intensive Care Unit mortality prediction task. In this unit, the physiological measurements used to make decisions have a problem with time irregularity. Leveraging the publicly available MIMIC-III, we compare the performance of our model to that of flagship models. In addition, we also performed extensive ablation studies to highlight the importance of specific components in our model. Interestingly enough, whenever data is collected 24 and 48 h after a patient's admission, we outperform our pioneering competitors, i.e., +1.1% and +1.5% for the AUC score, +2.3% and for the AUPRC score and +0.6% and +1.7%

 for the F1-score.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{el-amrani_2513,

title = {Error estimates for a viscosity-splitting scheme in time applied to non-Newtonian fluid flows},

author = {Mofdi El-Amrani and Anouar Obbadi and Mohammed Seaid and Driss Yakoubi},

url = {https://www.sciencedirect.com/science/article/pii/S0045782523007636?dgcid=coauthor},

year  = {2024},

date = {2024-02-01},

journal = {Computer Methods In Applied Mechanics And Engineering},

volume = {419},

number = {Feb. 2024},

pages = {116639},

abstract = {A time fractional-step method is presented for numerical solutions of the incompressible non-Newtonian fluids for which the viscosity is non-linear depending on the shear-rate magnitude according to a generic model. The method belongs to a class of viscosity-splitting procedures and it consists of separating the convection term and incompressibility constraint into two time steps. Unlike the conventional projection methods, the viscosity is not dropped in the last step allowing to enforce the full original boundary conditions on the end-of-step velocity which eliminates any concerns about the numerical boundary layers. We carry out a rigorous error analysis and provide a full first-order error estimate for both the velocity and pressure solutions in the relevant norms. Numerical results are presented for two test examples of non-

Newtonian fluid flows to demonstrate the theoretical analysis and confirm the reliability of this viscosity-splitting scheme.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{belhamadia_2366,

title = {Existence and uniqueness for a convective phase change model with temperature-dependent viscosity},

author = {Youssef Belhamadia and Jean Deteix and Basma Jaffal-Moutarda and Driss Yakoubi},

url = {https://www.sciencedirect.com/science/article/pii/S0022247X23005620?via%3Dihub},

year  = {2023},

date = {2023-11-01},

journal = {Journal Of Mathematical Analysis And Applications},

volume = {527},

number = {2},

pages = {127559},

abstract = {In this article, we consider a class of phase change model with temperature-dependent viscosity, convection and mixed boundary conditions on a bounded domain that reflect melting and solidification in a variety of real-world applications, such as metal casting and crystal growth. The mathematical model, which is based on the enthalpy formulation, takes into consideration the thermophysical differences between the liquid and solid states. The moving liquid-solid interface is explicitly fulfilled as the energy and momentum equations are solved over the full physical domain. Under particular assumptions, we derive various a priori estimates and prove well-posedness results. Numerical simulation of the model employed in the

paper is presented as an illustration of an example of a melting problem.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{kefi_2503,

title = {Toward Museum Transformation: From Mediation to Social Media-tion and Fostering Omni-visit Experience},

author = {Hajer Kefi and Ekatarina Besson and Yue Zhao and Sali FARRAN},

url = {https://www.sciencedirect.com/science/article/pii/S0378720623001386},

year  = {2023},

date = {2023-11-01},

journal = {Information & Management},

volume = {Available online 14 November 2023, 10389},

number = {Available},

pages = {Available online 14 November 2023, 10389},

abstract = {This article investigates the role played by Information and Communications Technology (ICT) and specifically social media in reshaping the mediation (?Kulturvermittlung') processes enacted by museums along with their digital transformation. We apply a multi-methods research design, including qualitative research conducted within a selection of museums in France, an intercept study at Le Louvre Museum (Paris, France) and finally an online survey. Our findings concurrently put forward the concept of social mediation and illustrate the changing role of museum mediation processes that imply the transformation of visitor experience from a receptive format (consuming informative and entertaining content) to an interactive and collaborative format, through the use of social media and other ICT tools deployed and used complementarily to fulfill visitors needs and gratifications and foster what we call the visitor ?omni-visit experience'. Both theoretical and managerial implications are considered.},

keywords = {},

pubstate = {online},

tppubtype = {article}

}

@article{bernard_2401,

title = {On the Homogenization of the Renewal Equation with Heterogeneous External Constraints},

author = {Etienne Bernard and Francesco Salvarani},

url = {https://link.springer.com/article/10.1007/s10440-023-00594-2},

year  = {2023},

date = {2023-10-01},

journal = {Acta Applicandae Mathematicae},

volume = {187},

number = {1},

pages = {4},

abstract = {We study the homogenization limit of the renewal equation with heterogeneous external con- straints by means of the two-scale convergence theory. We prove that the homogenized limit satisfies an equation involving non-local terms, which are the consequence of the oscillations in the birth and death terms. We have moreover shown that the numerical approximation of the homogenized equation via the two-scale limit gives an alternative way for the numerical study of the solution of the limiting problem.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{salhi_2456,

title = {Convergence analysis of a class of iterative methods for propagation of reaction fronts in porous media},

author = {Loubna Salhi and Mohammed Seaid and Driss Yakoubi},

url = {https://www.sciencedirect.com/science/article/pii/S0045782523006485?dgcid=author},

year  = {2023},

date = {2023-10-01},

journal = {Computer Methods In Applied Mechanics And Engineering},

volume = {418},

number = {Part A},

pages = {116524},

abstract = {We present an iterative scheme for the numerical analysis of propagating reaction front problems in porous media satisfying an Arrhenius-type law. The governing equations consist of the Darcy equations for the pressure and flow field coupled to two convection-diffusion-reaction equations for the temperature and depth of conversion.

 Well-posedness, existence and uniqueness of the weak solution are first studied using a fixed-point approach and then, analysis of the proposed iterative scheme is investigated. Numerical results are also presented in order

to validate the theoretical estimates and to illustrate the performance of the proposed scheme.

The obtained results are in line with our expectations for a good numerical resolution with high accuracy and stability behaviors.},

keywords = {},

pubstate = {accepted},

tppubtype = {article}

}

@article{vazquez_hernandez_2473,

title = {Female advertising models and their body mass index (BMI): How does BMI similarity affect perceived product quality?},

author = {Erik Ernesto Vazquez Hernandez and Reto Felix and Lorena Siliceo},

url = {https://onlinelibrary.wiley.com/doi/10.1002/cb.2274},

year  = {2023},

date = {2023-10-01},

journal = {Journal Of Consumer Behaviour},

volume = {74},

number = {10},

pages = {1002},

abstract = {Recent research has pointed out the importance of appearance similarity as a special instance of homophily. The current paper introduces body mass index (BMI) similarity as a convenient and powerful proxy of perceived appearance homophily in the context of female advertising models by showing process evidence and boundary conditions for the effect of BMI similarity on marketing-relevant downstream variables. Study 1 tests how BMI similarity relates to a traditional measure of appearance homophily and perceived reliability of a female advertising model. Study 2 shows that BMI similarity influences perceived product quality and purchase intention. Website vividness negatively moderates the relationship between BMI similarity and product quality. Study 3 tests for alternative explanations and provides support for the mediating effect of appearance homophily for the relationship between BMI similarity and perceived product quality. The findings provide marketing managers with important insights on how to increase their marketing effectiveness by integrating BMI similarity into their marketing communications. Additionally, using BMI similarity serves as an alternative way to promote diversity and inclusion of models with plus-size body type often sought by societal brands.},

keywords = {},

pubstate = {online},

tppubtype = {article}

}

@article{bernis_2476,

title = {Interest rates term structure models driven by Hawkes processes},

author = {Guillaume Bernis and Matthieu Garcin and Simone Scotti and Carlo Sgarra},

url = {https://epubs.siam.org/doi/10.1137/22M1502604},

year  = {2023},

date = {2023-10-01},

journal = {Siam Journal On Financial Mathematics},

volume = {14},

number = {4},

pages = {1062-1079},

abstract = {This paper includes a marked Hawkes process in the original HJM set-up, and investigates the impact of this assumption on the pricing of the popular vanilla fixed-income derivatives.

Our model exhibits a smile that can fit the implied volatility of swaptions for a given key rate (tenor). We harness on the log-normality of the model, conditionally with respect to jumps, and derive formulae to evaluate both caplets/floorlets and swaptions. Our model exhibits negative jumps on the zero-coupon (hence positive on the rates). Therefore, its behaviour is compatible with the situation where globally low interest rates can suddenly show cluster of positive jumps in case of tensions on the market. One of the main difficulties when dealing with the HJM model is to keep a framework that is Markovian. In particular, it is important to preserve the important features of the Hull and White version, especially the reconstruction formula that provides the zero-coupon bonds in terms of the underlying model factors. In our case, this formula is based on two factors: a classical Gaussian part and a pure jump martingale part based on a Hawkes process.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{garcin_2477,

title = {Estimation of time-varying kernel densities and chronology of the impact of COVID-19 on financial markets},

author = {Matthieu Garcin and Jules Klein and Sana Laaribi},

url = {https://www.tandfonline.com/doi/abs/10.1080/02664763.2023.2272226},

year  = {2023},

date = {2023-10-01},

journal = {Journal Of Applied Statistics},

volume = {not yet available},

number = {not yet av},

pages = {not yet available},

abstract = {The time-varying kernel density estimation relies on two free parameters: the bandwidth and the discount factor. We propose to select these parameters so as to minimize a criterion consistent with the traditional requirements of the validation of a probability density forecast. These requirements are both the uniformity and the independence of the so-called probability integral transforms, which are the forecast time-varying cumulated distributions applied to the observations. We thus build a new numerical criterion incorporating both the uniformity and independence properties by the mean of an adapted Kolmogorov-Smirnov statistic. We apply this method to financial markets during the onset of the COVID-19 crisis. We determine the time-varying density of daily price returns of several stock indices and, using various divergence statistics, we are able to describe the chronology of the crisis as well as regional disparities. For instance, we observe a more limited impact of COVID-19 on financial markets in China, a strong impact in the US, and a slow recovery in Europe.},

keywords = {},

pubstate = {online},

tppubtype = {article}

}

@article{amirat_2247,

title = {Homogenization of ferrofluid flow models in porous media with Langevin magnetization law},

author = {Youcef Amirat and Kamel Hamdache},

url = {https://www.sciencedirect.com/science/article/pii/S0022247X23001324?via%3Dihub},

year  = {2023},

date = {2023-09-01},

journal = {Journal Of Mathematical Analysis And Applications},

volume = {525},

number = {1},

pages = {127129},

abstract = {The paper is concerned with the homogenization of the equations describing the flow of a ferrofluid through a heterogeneous porous medium ? in the presence of an applied magnetic field. We discuss two models where the magnetization M is parallel to the magnetic field H. In the first one M and H satisfy the relation M=?01?fH in ?, where ?0 is a positive constant and 1?f is the characteristic function of ?f (the pore space). In the second model, M and H satisfy the Langevin magnetization law M=MsL(b1|H|)|H|1?fH, where L is the Langevin function given by L(x)=1tanh?x?1x, Ms is the saturation magnetization and b1 is a positive physical constant. The velocity and the pressure satisfy the Stokes equation with a Kelvin magnetic force. We perform the homogenization of the equations of each of the two models. Using the two-scale convergence method, we rigorously derive the homogenized equation for the magnetic potential and determine the asymptotic limit of the magnetization. Then we rigorously derive a Darcy law.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{fortin_2280,

title = {High accuracy breaking point detection for stiff DDEs},

author = {André Fortin and Driss Yakoubi},

url = {https://www.sciencedirect.com/science/article/abs/pii/S0893965923000976#d1e179},

year  = {2023},

date = {2023-09-01},

journal = {Applied Mathematics Letters},

volume = {143},

pages = {108665},

abstract = {We have recently introduced a very high order Discontinuous Galerkin (DG) method for the solution of stiff ordinary differential equations (ODEs) and delay differential equations (DDEs). In this communication we focus on the detection of breaking points frequently arising in the solution of stiff DDEs. Breaking points are discontinuities appearing in the solution of DDEs and/or in some of its derivatives. Breaking points affect the efficiency of the numerical method by forcing very small time steps in their vicinity. They also locally affect the solution accuracy. We therefore introduce a very simple breaking point detection algorithm in order to further improve the efficiency our DG method.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{salvarani_2286,

title = {Homogenization of the linear Boltzmann equation with a highly oscillating scattering term in extended phase space},

author = {Francesco Salvarani and Etienne Bernard},

url = {https://doi.org/10.1016/j.aml.2023.108672},

year  = {2023},

date = {2023-09-01},

journal = {Applied Mathematics Letters},

volume = {143},

pages = {108672},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{vazquez_hernandez_2341,

title = {Images, reviews, and purchase intention on social commerce: The role of  mental imagery vividness, cognitive and affective social presence},

author = {Erik Ernesto Vazquez Hernandez and Chirag Patel and Salvador Alvidrez and Lorena Siliceo},

url = {https://www.sciencedirect.com/science/article/abs/pii/S0969698923001625?via%3Dihub},

year  = {2023},

date = {2023-09-01},

journal = {Journal Of Retailing And Consumer Services},

volume = {74},

pages = {103415},

abstract = {Images and textual reviews are central to social commerce sites. But little is known about the mechanism by which image quality and type of textual review (with personal experiences versus facts) impact consumer purchase intention on a social commerce page. We address this knowledge gap and use the stimulus-organism-response (S-O-R) framework to develop our conceptual framework. We hypothesize that image quality and type of textual review impact purchase intention through imagery vividness that functions as a stimulus. Further, imagery vividness impacts purchase intention positively in the social commerce context through social presence. Specifically, the effect of imagery vividness on purchase intention is likely to be serially mediated by cognitive social presence and affective social presence. We collect data by conducting two experiments using a social media post regarding fashion apparel for middle-aged women on Instagram and find support for our thesis.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{sama_2301,

title = {Effect of temperature anisotropy on the dynamics of geodesic acoustic modes},

author = {Juvert Njeck Sama and Alessandro Biancalani and Alberto Bottino and I Chavdarovski and Daniele Del Sarto and A Ghizzo and Thomas Hayward-Schneider and Philipp Lauber and B Rettino and Francesco Vannini},

url = {https://www.cambridge.org/core/journals/journal-of-plasma-physics/article/abs/effect-of-temperature-anisotropy-on-the-dynamics-of-geodesic-acoustic-modes/B3084D49F9505CDF3AA53221EE074E46},

year  = {2023},

date = {2023-08-01},

journal = {Journal Of Plasma Physics},

volume = {89},

number = {1},

pages = {905890109},

abstract = {In this work, we revisit the linear gyro-kinetic theory of geodesic acoustic modes (GAMs) and derive a general dispersion relation for an arbitrary equilibrium distribution function of ions. A bi-Maxwellian distribution of ions is then used to study the effects of ion temperature anisotropy on GAM frequency and growth rate. We find that ion temperature anisotropy yields sensible modifications to both the GAM frequency and growth rate as both tend to increase with anisotropy and these results are strongly affected by the electron to ion temperature ratio.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{yakoubi_2302,

title = {Enhancing the viscosity-splitting method to solve the time-dependent Navier-Stokes equations},

author = {Driss Yakoubi},

url = {https://www.sciencedirect.com/science/article/abs/pii/S100757042300182X},

year  = {2023},

date = {2023-08-01},

journal = {Communications In Nonlinear Science And Numerical Simulation},

volume = {123},

pages = {107264},

abstract = {The viscosity-splitting (VS) scheme for solving the incompressible time-dependent Navier-Stokes equations consists to decouple the full problem into two easy subproblems to resolve.

This method splits the nonlinearity (convection term) and the incompressibility into two different steps. As a result, every subproblem is easier to solve than the Navier-Stokes system. The semi-implicit approach is mostly used in the first step for the nonlinearity term and the intermediate velocity is calculated by dropping the pressure gradient. We then resolve a linear Stokes problem in the next step.

We present a modified viscosity-splitting scheme (Incremental viscosity-splitting) (IVS) to improve this method. This scheme adds the gradient of the pressure (calculated at the previous time step) in the first step and modifies the Stokes equations in the second step to

predict a better value of the intermediate velocity. A manufactured solution and two well-known benchmarks will be used to demonstrate the effectiveness of the suggested strategy.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{charles_2316,

title = {Mathematical and numerical study of a kinetic model describing the evolution of planetary rings},

author = {Frédérique Charles and Annamaria Massimini and Francesco Salvarani},

url = {https://www.sciencedirect.com/science/article/pii/S0898122123001724},

year  = {2023},

date = {2023-08-01},

journal = {Computers & Mathematics With Applications},

volume = {143},

pages = {48-56},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{waga_2351,

title = {Analytical and Deep Learning Approaches for Solving the Inverse kinematic Problem of a High Degrees of Freedom Robotic Arm},

author = {Nesrine Waga and Hichem Kallel and Nédra Mellouli},

url = {https://www.sciencedirect.com/science/article/pii/S0952197623004852?via%3Dihub},

year  = {2023},

date = {2023-08-01},

journal = {Engineering Applications Of Artificial Intelligence},

volume = {123},

number = {Part B},

pages = {106301},

abstract = {Inverse kinematics is the basis for controlling the motion of robotic manipulators. It defines the required joint variables for the robotic end-effector accurately reach the desired location. Due to the derivation difficulty, computation complexity, singularity problem, and redundancy, analytical Inverse kinematics solutions pose numerous challenges to the operation of many robotic arms, especially for a manipulator with a high degree of freedom. This paper develops different Deep Learning networks for solving the Inverse kinematics problem of six- Degrees of Freedom robotic manipulators. The implemented neural architectures are Artificial Neural Network, Convolutional Neural Network, Long-Short Term Memory, Gated Recurrent Unit, and Bidirectional Long-Short Term Memory. In this context, we associate the proposed results with a specific tuning of Deep Learning network hyper-parameters (number of hidden layers, learning rate, Loss function, optimization algorithm, number of epochs, etc.). The Bidirectional Long-Short Term Memory network outperformed all proposed architectures. To be close as possible to the experimental results, we have included two types of noise in the training data set to validate which of the five proposed neural networks is more efficient. Furthermore, in this study, we compare the performance of analytical and soft computing solutions in generating robots' trajectories. We include this scenario, focusing on the advantage of implementing neural networks in avoiding the singularity problem that can occur using the analytical approach. In addition, we used the RoboDK simulator to show simulation results with real-world meaning. The performance of Deep Learning models depends on the complexity of the posed problem. Moreover, the complexity of the Inverse Kinematics problem is related to the number of Degrees of Freedom. At the end of this work, we evaluate the influence of the complexity of robotic manipulators on the proposed Deep Learning networks' performance. The results show that the implemented Deep Learning mechanisms performed well in reaching the desired pose of the end-effector. The proposed inverse kinematics strategies apply to other manipulators with different numbers of Degrees of Freedom.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{balti_2397,

title = {Spatio-temporal Heterogeneous Graph using Multivariate Earth Observation Time Series: Application for drought forecasting},

author = {Hanen Balti and Ali Ben Abbes and Yanfang Sang and Nédra Mellouli and Imed Riadh Faraha},

url = {https://www.sciencedirect.com/science/article/pii/S0098300423001395?via%3Dihub},

year  = {2023},

date = {2023-08-01},

journal = {Computers & Geosciences},

volume = {179},

number = {october 20},

pages = {105435},

note = {Accurate forecasting is required for the effective risk management of drought disasters. Many machine learning- and deep learning-based models have been proposed for drought forecasting, however, they cannot handle the temporal and/or spatial dependencies in the input data, causing unexpected forecasting results. In order to solve the challenging issue, in this paper we proposed the Heterogeneous Spatio-Temporal Graph (HetSPGraph), for drought forecasting. It includes three major layers: spatial aggregations including inter and intra aggregations, temporal aggregation, and a forecasting network. The main function of HetSPGraph is to learn the dynamic spatiotemporal correlations between the regions and to further predict the drought in different regions, based on which accurate drought forecasting can be achieved. Experimental forecasting results of the Standardized Precipitation Evapotranspiration Index (SPEI) in China indicated that the HetSPGraph model outperformed the traditional baseline methods including the Long Short-Term Memory model (LSTM), Convolutional Neural Network-LSTM (CNN-LSTM), Gated Recurrent Unit (GRU), Spatio-Temporal Graph Convolutional Networks (STGCN) and Geographic-Semantic-Temporal Hypergraph Convolutional Network (GST-HCN). Even for long-term forecasting (12 months), more accurate forecasting results, with the coefficient of determination 

 higher than 0.89, can also be obtained by HetSPGraph compared to the other three models. The proposed HetSPGraph model has the potential for wider use in forecasting drought and other natural disasters.},

keywords = {},

pubstate = {online},

tppubtype = {article}

}

@article{talhouk_2369,

title = {On well-posedness for some Korteweg-de Vries type equations with variable coefficients},

author = {Raafat Talhouk and Luc Molinet and Ibtissame Zaiter},

url = {https://doi.org/10.1007/s00028-023-00904-z},

year  = {2023},

date = {2023-07-01},

journal = {Journal Of Evolution Equations},

volume = {23},

number = {3},

pages = {52},

abstract = {In this paper, KdV-type equations with time- and space-dependent coefficients are considered. Assuming that the dispersion coefficient in front of uxxx is positive and uniformly bounded away from zero and that a primitive function of the ratio between the anti-dissipation and the dispersion coefficients is bounded from below, we prove the existence and uniqueness of a solution u such that hu belongs to a classical Sobolev space, where h is a function related to this ratio. The LWP in Hs(R), s > 1/2, in the classical (Hadamard) sense is also proven under this time an assumption of boundedness of the above primitive function. Our approach combines a change of unknown with dispersive estimates. Note that previous results were restricted to Hs(R), s > 3/2, and only used the dispersion to compensate the anti-dissipation and not to lower the Sobolev index required for well-posedness.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{hamdache_2246,

title = {The Bloch-Torrey limit of a kinetic transport system},

author = {Kamel Hamdache and Djamila Hamroun},

url = {https://link.springer.com/article/10.1007/s00009-023-02328-y#citeas},

year  = {2023},

date = {2023-06-01},

journal = {Mediterranean Journal Of Mathematics},

volume = {20},

number = {3},

pages = {122},

abstract = {This work is devoted to highlighting the diffusion of some models of Kinetic-Bloch system by an asymptotic analysis. The limit of the kinetic equation when using the classical diffusion scaling shows that the magnetization field becomes parallel to the magnetic field. For the limit of the magnetization when we use a second scaling of the kinetic equation, we show that the dynamics of the magnetization is driven by the Bloch-Torrey diffusion equation.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{bousbia_2353,

title = {Augmented spectral formulation for the Stokes problem with variable viscosity and mixed boundary conditions},

author = {Chaima Bousbia and Yasmina Daikh and Sarra Maarouf and Driss Yakoubi},

url = {https://link.springer.com/article/10.1007/s10092-023-00530-8},

year  = {2023},

date = {2023-06-01},

journal = {Calcolo},

volume = {60},

number = {3},

pages = {36},

abstract = {This paper deals with the analysis of a new augmented formulation in terms of vorticity, velocity and pressure for the Stokes equations with variable viscosity and mixed boundary conditions. The well-posedness of the continuous problem holds under assumptions on the viscosity. When the domain is a parallelepiped, the spectral discretization is proposed using the Galerkin method with numerical integration. Then, we prove the well-posedness of the obtained discrete problem under the same type of conditions on the viscosity. A priori error estimates is then derived for the three

unknowns. Finally, numerical experiments are presented that confirm the interest of

the discretization.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{bader_1995,

title = {Microscopic tridomain model of electrical activity in the heart with dynamical gap junctions. Part 2 - Derivation of the macroscopic tridomain model by unfolding homogenization method},

author = {Fakhrielddine Bader and Mostafa Bendahmane and Mazen Saad and Raafat Talhouk},

url = {https://doi.org/10.3233/ASY-221804},

year  = {2023},

date = {2023-05-01},

journal = {Asymptotic Analysis},

volume = {132},

number = {3-4},

pages = {575-606},

abstract = {We study the homogenization of a novel microscopic tridomain system, allowing

for a more detailed analysis of the properties of cardiac conduction than the classical bidomain

and monodomain models. In [5], we detail this model in which gap junctions are considered

as the connections between adjacent cells in cardiac muscle and could serve as alternative

or supporting pathways for cell-to-cell electrical signal propagation. Departing from this mi-

croscopic cellular model, we apply the periodic unfolding method to derive the macroscopic

tridomain model. Several diculties prevent the application of unfolding homogenization

results, including the degenerate temporal structure of the tridomain equations and a nonlin-

ear dynamic boundary condition on the cellular membrane. To prove the convergence of the

nonlinear terms, especially those dened on the microscopic interface, we use the boundary

unfolding operator and a Kolmogorov-Riesz compactness's result.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{dabaghi_2223,

title = {Tensor approximation of the self-diffusion matrix of tagged particle processes},

author = {Jad Dabaghi and Virginie Ehrlacher and Christoph Strossner},

url = {https://www.sciencedirect.com/science/article/pii/S0021999123001122},

year  = {2023},

date = {2023-05-01},

journal = {Journal Of Computational Physics},

volume = {480},

pages = {112017},

abstract = {The objective of this paper is to investigate a new numerical method for the approximation of the self-diffusion matrix of a tagged particle process defined on a grid. While standard numerical methods make use of long-time averages of empirical means of deviations of some stochastic processes, and are thus subject to statistical noise, we propose here a tensor method in order to compute an approximation of the solution of a high-dimensional quadratic optimization problem, which enables to obtain a numerical approximation of the self-diffusion matrix. The tensor method we use here relies on an iterative scheme which builds low-rank approximations of the quantity of interest and on a carefully tuned variance reduction method so as to evaluate the various terms arising in the functional to minimize. In particular, we numerically observe here that it is much less subject to statistical noise than classical approaches.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{maar_2324,

title = {Should brands foster their Instagram account followers' fear of missing out by posting ephemeral content?},

author = {Daniel Maar and Hajer Kefi and Mehmet A. Orhan},

url = {https://journals.sagepub.com/doi/10.1177/20515707231161808},

year  = {2023},

date = {2023-05-01},

journal = {Recherche et Application en Marketing},

abstract = {Several blogs and websites with a focus on social media marketing suggest that brands can benefit from fostering their Instagram account followers' fear of missing out (FoMO) by posting ephemeral content. Relying on an online survey with 550 followers of Instagram brand accounts and a scenario-based experiment with 535 participants, this article shows that content ephemerality triggers followers' FoMO, which increases brand account engagement and brand account fatigue. Brand account engagement (fatigue), in turn, positively (negatively) relates to brand attitude and brand attachment. Further analyses reveal that the total effect of followers' FoMO on brand attachment is positive and significant, while the total effect of FoMO on brand attitude is not significant. Moreover, content ephemerality has a negative and significant total effect on brand attitude. A key implication of these findings is that it is not beneficial for brands to foster their Instagram account followers' FoMO by posting ephemeral content.},

keywords = {},

pubstate = {online},

tppubtype = {article}

}

@article{fortin_2076,

title = {A very high order discontinuous Galerkin method for the numerical solution of stiff DDEs},

author = {André Fortin and Driss Yakoubi},

url = {https://www.sciencedirect.com/science/article/pii/S0096300322008359},

year  = {2023},

date = {2023-04-01},

journal = {Applied Mathematics And Computation},

volume = {443},

pages = {127767},

abstract = {We present a high order discontinuous Galerkin (DG) method for the numerical solution of systems of delay differential equations (DDEs). The method is based on Legendre orthogonal polynomials of high degree k (typically k=10) in each subinterval and is a generalisation to DDEs of a similar method which proved to be very efficient for ordinary differential equations (ODEs). We show how the error can be estimated allowing to control the size of the time step. We also propose a particularly efficient quasi Newton method for the solution of the resulting non linear systems based on a very accurate approximation of the Jacobian matrix that is very easy to implement and with excellent convergence properties. The method is then applied to very stiff systems of DDEs.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{boussoufa_2305,

title = {Numerical analysis for backward Euler spectral discretization for Stokes equations with boundary conditions involving the pressure: part I},

author = {Oussama Boussoufa and Yasmina Daikh and Driss Yakoubi},

url = {https://link.springer.com/article/10.1007/s10092-023-00520-w},

year  = {2023},

date = {2023-04-01},

journal = {Calcolo},

volume = {60},

number = {2},

pages = {1--27},

abstract = {In this paper, we address the study of the time-dependent Stokes system with boundary conditions involving the pressure. We obtain existence and uniqueness for a classof Lipschitz-continuous domains. Next, a spectral discretizations of the problem is

proposed combined with the backward Euler scheme. The discrete spaces are defined in a way to give exactly divergence-free discrete approximations for the velocity. Then, we prove the associated discrete inf-sup condition and derive a priori error estimates.

Finally, some numerical experiments are presented},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{mishchenko_2378,

title = {Numerical tools for burning plasmas},

author = {Alexey Mishchenko and Alessandro Biancalani and Juvert Njeck Sama and Alberto Bottino and Sergio Briguglio and M Borchardt and Emanuele Poli and Remi Dumont and Jorge Ferreira and J P Graves and Ralf Kleiber and B Rettino and Thomas Hayward-Schneider and Axel Koenies and Emmanuel Lanti and Philipp Lauber and H Leyh and Zhixin Lu and Hinrich Luetjens and Ben McMillan and Martin Campos Pinto and Baruch Rofman and Christoph Slaby and Francesco Vannini and Laurent Villard and Gregorio Vlad and Xin Wang and Fabien Widmer and Fulvio Zonca},

url = {https://iopscience.iop.org/article/10.1088/1361-6587/acce68},

year  = {2023},

date = {2023-04-01},

journal = {Plasma Physics And Controlled Fusion},

volume = {65},

number = {6},

pages = {064001},

abstract = {The software stack under development within a European coordinated effort on tools for burning plasma modelling is presented. The project is organised as a Task (TSVV Task 10) under the new E-TASC initiative (Litaudon et al 2022 Plasma Phys. Control. Fusion64 034005). This is a continued effort within the EUROfusion inheriting from the earlier European coordination projects as well as research projects based at various European laboratories. The ongoing work of the TSVV Tasks is supported by the Advanced Computing Hubs. Major projects requiring the high performance computing (HPC) resources are global gyrokinetic codes and global hybrid particle-magnetohydrodynamics (MHD) codes. Also applications using the integrated modelling tools, such as the Energetic-Particle Workflow, based on the ITER Integrated Modelling & Analysis Suite (IMAS), or the code package for modelling radio-frequency heating and fast-ion generation may require intensive computation and a substantial memory footprint. The continual development of these codes both on the physics side and on the HPC side allows us to tackle frontier problems, such as the interaction of turbulence with MHD-type modes in the presence of fast particles. One of the important mandated outcomes of the E-TASC project is the IMAS-enabling of EUROfusion codes and release of the software stack to the EUROfusion community.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{zoia_1969,

title = {A hybrid parareal Monte-Carlo algorithm for parabolic problems},

author = {Andrea Zoia and Yvon Maday and Jad Dabaghi},

url = {https://www.sciencedirect.com/science/article/abs/pii/S0377042722004071},

year  = {2023},

date = {2023-03-01},

journal = {Journal Of Computational And Applied Mathematics},

volume = {420},

pages = {114800},

abstract = {In this work, we propose a hybrid Monte Carlo/deterministic ??parareal-in-time'' approach devoted to accelerating Monte Carlo simulations over massively parallel computing environments for the simulation of time-dependent problems.

This parareal approach iterates on two different solvers: a low-cost ??coarse'' solver

based on a very cheap deterministic Galerkin scheme and a ??fine'' solver based on a

high-fidelity Monte Carlo resolution.

In a set of benchmark numerical experiments based on a toy model concerning

the time-dependent diffusion equation, we compare our hybrid parareal strategy with

a standard full Monte Carlo solution. In particular, we show that for a large number

of processors, our hybrid strategy significantly reduces the computational time of the

simulation while preserving its accuracy. The convergence properties of the proposed

Monte Carlo/deterministic parareal strategy are also discussed.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{grasselli_2053,

title = {A fully quantization-based scheme for FBSDEs},

author = {Martino Grasselli and Gorgia Callegaro and Alexandro Gnoatto},

url = {https://www.sciencedirect.com/science/article/abs/pii/S0096300322007251},

year  = {2023},

date = {2023-03-01},

journal = {Applied Mathematics And Computation},

volume = {441},

pages = {127666},

abstract = {We propose a quantization-based numerical scheme for a family of decoupled forward-backward stochastic differential equations. We simplify the scheme for the control in Pages and Sagna(2018) so that our approach is fully based on recursive marginal quantization and does not involveany Monte Carlo simulation for the computation of conditional expectations. We analyse in detail thenumerical error of our scheme and provide some examples of application to financial mathematics.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{maar_2215,

title = {Fostering positive customer attitudes and usage intentions for scheduling services via chatbots},

author = {Daniel Maar and Hajer Kefi and Ekaterina Besson},

url = {https://doi.org/10.1108/JOSM-06-2021-023},

year  = {2023},

date = {2023-03-01},

journal = {Journal Of Service Management},

volume = {34},

number = {2},

pages = {208-230},

abstract = {Purpose



This article draws on a reasoned action perspective and the two fundamental dimensions (i.e. warmth and competence) of the Stereotype Content Model (SCM) to analyze customers' chatbot-related attitudes and usage intentions in service retailing. The authors investigate how chatbot, customer, and contextual characteristics, along with perceptions of chatbot warmth and competence, shape customers' chatbot-related attitudes. Furthermore, the authors analyze whether the customer generation or the service context moderates the relationship between chatbot-related attitudes and usage intentions.

Design/methodology/approach



The results are based on two studies (N = 807). Study 1 relies on a 2 (chatbot communication style: high vs low social orientation) × 2 (customer generation: generation X [GenX] vs generation Z [GenZ]) × 2 (service context: restaurant vs medical) between-subjects design. Study 2 relies on a similar number of respondents from GenX and GenZ who answered questions on scheduling a service with either the dentist or the favorite restaurant of the respondents.

Findings



GenZ shows more positive attitudes toward chatbots than GenX, due to higher perceptions of warmth and competence. While GenZ has similar attitudes toward chatbots with a communication style that is high or low in social orientation, GenX perceives chatbots with a high social orientation as warmer and has more favorable attitudes toward chatbots. Furthermore, the positive effect of chatbot-related attitudes on usage intentions is stronger for GenX than GenZ. These effects do not significantly differ between the considered contexts.

Originality/value



This research formulates future directions to stimulate debate on factors that service retailers should consider when employing chatbots.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{harfouche_1996,

title = {The Recursive Theory of Knowledge Augmentation: Integrating human intuition and knowledge in Artificial Intelligence to augment organizational knowledge},

author = {Antoine Harfouche and Bernard Quinio and Mario Saba and Peter Saba},

url = {https://link.springer.com/article/10.1007/s10796-022-10352-8},

year  = {2023},

date = {2023-02-01},

journal = {Information Systems Frontiers},

volume = {25},

pages = {55-70},

abstract = {Artificial intelligence (AI) has increased the ability of organizations to accumulate tacit and explicit knowledge to inform management decision-making. Despite the hype and popularity of AI, there is a noticeable scarcity of research focusing on AI's potential role in enriching and augmenting organizational knowledge. This paper develops a recursive theory of knowledge augmentation in organizations (the KAM model) based on a synthesis of extant literature and a four-year revised canonical action research project. The project aimed to design and implement a human-centric AI (called Project) to solve the lack of integration of tacit and explicit knowledge in a scientific research center (SRC). To explore the patterns of knowledge augmentation in organizations, this study extends Nonaka's SECI (socialization, externalization, combination, and internali- zation) model by incorporating the human-in-the-loop Informed Artificial Intelligence (IAI) approach. The proposed design offers the possibility to integrate experts' intuition and domain knowledge in AI in an explainable way. The findings show that organizational knowledge can be augmented through a recursive process enabled by the design and implementation of human-in-the-loop IAI. The study has important implications for research and practice.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{borsoni_1875,

title = {Compactness property of the linearized Boltzmann operator for a polyatomic gas undergoing resonant collisions},

author = {Thomas Borsoni and Laurent Boudin and Francesco Salvarani},

url = {https://www.sciencedirect.com/science/article/pii/S0022247X22005935?via%3Dihub},

year  = {2023},

date = {2023-01-01},

journal = {Journal Of Mathematical Analysis And Applications},

volume = {517},

number = {1},

pages = {126579},

abstract = {In this paper, we investigate a compactness property of the linearized Boltzmann operator in the context of a polyatomic gas whose molecules undergo resonant collisions. The peculiar structure of resonant collision rules allows to tensorize the problem into a velocity-related one, neighbouring the monatomic case, and an internal energy-related one. Our analysis is based on a specific treatment of the internal energy contributions. We also propose a geometric variant of Grad's proof of the same compactness property in the monatomic case.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}