The Experts below are selected from a list of 303 Experts worldwide ranked by ideXlab platform

Stefan Stieglitz - One of the best experts on this subject based on the ideXlab platform.

  • Dynamics of Convergence Behaviour in social media crisis communication – a complexity perspective
    Information Technology & People, 2021
    Co-Authors: Milad Mirbabaie, Stefan Stieglitz, Felix Brünker
    Abstract:

    PurposeThe purpose of this study is to investigate communication on Twitter during two unpredicted crises (the Manchester bombings and the Munich shooting) and one natural disaster (Hurricane Harvey). The study contributes to understanding the dynamics of Convergence Behaviour archetypes during crises.Design/methodology/approachThe authors collected Twitter data and analysed approximately 7.5 million relevant cases. The communication was examined using social network analysis techniques and manual content analysis to identify Convergence Behaviour archetypes (CBAs). The dynamics and development of CBAs over time in crisis communication were also investigated.FindingsThe results revealed the dynamics of influential CBAs emerging in specific stages of a crisis situation. The authors derived a conceptual visualisation of Convergence Behaviour in social media crisis communication and introduced the terms hidden and visible network-layer to further understanding of the complexity of crisis communication.Research limitations/implicationsThe results emphasise the importance of well-prepared emergency management agencies and support the following recommendations: (1) continuous and (2) transparent communication during the crisis event as well as (3) informing the public about central information distributors from the start of the crisis are vital.Originality/valueThe study uncovered the dynamics of crisis-affected Behaviour on social media during three cases. It provides a novel perspective that broadens our understanding of complex crisis communication on social media and contributes to existing knowledge of the complexity of crisis communication as well as Convergence Behaviour.

  • Convergence Behaviour of Bystanders: An Analysis of 2016 Munich Shooting Twitter Crisis Communication
    arXiv: Social and Information Networks, 2019
    Co-Authors: Deborah Bunker, Milad Mirbabaie, Stefan Stieglitz
    Abstract:

    While Convergence Behaviour archetypes can explain Behaviour of individuals who actively converge on and participate in crises, less is known about individuals who converge on an event and choose to remain passive i.e. "bystanders". Bystanders are important, because of their proximity to an event and their function as an "eye-witness". To investigate the role of bystanders in crisis communications we analysed Twitter communication generated from the 2016 Munich Shooting event. Our findings revealed the impassive Convergence Behaviour archetype could influence an event as a passive and rational "eye-witness", by gathering and sharing information close to where the event is occurring.

  • Who Sets the Tone? Determining the Impact of Convergence Behaviour Archetypes in Social Media Crisis Communication
    Information Systems Frontiers, 2019
    Co-Authors: Milad Mirbabaie, Deborah Bunker, Stefan Stieglitz, Annika Deubel
    Abstract:

    Convergence Behaviour Archetypes (CBA) describe the Behavioural traits of individuals who spontaneously and collectively move towards emergency situations. If Convergence is not managed effectively, unintended crisis management issues may emerge and lead to an exacerbation of the crisis situation. Social media users express different Behavioural intentions while converging on a crisis. While these Behavioural intentions have been analysed in previous research, an understanding of Convergence Behaviour facilitated by social media use to an effective and smart level of control, is yet to be achieved. Manual content and social network analyses were conducted on our Twitter dataset of the Manchester Bombing 2017 and this analysis identified three dominant Convergence Behaviour archetypes i.e. the Helpers, the Mourners and the Detectives. These archetypes had the highest crisis communications impact regarding their retweet Behaviour. This work provides a better theoretical understanding of Convergence Behaviour archetype influence and impact on crisis communication, for Information Systems research and practice.

  • TDIT - Examining Convergence Behaviour During Crisis Situations in Social Media - A Case Study on the Manchester Bombing 2017
    Smart Working Living and Organising, 2018
    Co-Authors: Milad Mirbabaie, Deborah Bunker, Annika Deubel, Stefan Stieglitz
    Abstract:

    Convergence Behaviour Archetypes (CBA) describe the many different ways that individuals spontaneously and collectively move towards an emergency situation. If this movement is not managed effectively, crisis management issues and problems can emerge and lead to an exacerbation of the crisis situation e.g. panic, Convergence of people and resources towards danger, Convergence of excess and unrequired people and resources etc. Users of social media platforms express different motivations and Behaviours while converging on a crisis. While this Behaviour has been analysed in previous research, an understanding of Convergence Behaviour facilitated by social media platforms to an effective level of control, is yet to be achieved. This paper examines how Twitter users, converged on the Manchester Bombing 2017. We identified the most impactful Convergence Behaviour archetypes, including those with the highest perceived legitimacy of Convergence i.e. those deemed by the Twitter network, to have a necessary and meaningful role in the crisis. Manual content and social network analyses were conducted on our data by identifying three roles that determine the Twitter users with the highest impact regarding their retweet Behaviour. We determined that Helpers, Mourners and Detectives had the highest impact on crisis communication in this event.

  • Examining Convergence Behaviour During Crisis Situations in Social Media - A Case Study on the Manchester Bombing 2017
    2018
    Co-Authors: Milad Mirbabaie, Deborah Bunker, Annika Deubel, Stefan Stieglitz
    Abstract:

    Convergence Behaviour Archetypes (CBA) describe the many different ways that individuals spontaneously and collectively move towards an emergency situation. If this movement is not managed effectively, crisis management issues and problems can emerge and lead to an exacerbation of the crisis situation e.g. panic, Convergence of people and resources towards danger, Convergence of excess and unrequired people and resources etc. Users of social media platforms express different motivations and Behaviours while converging on a crisis. While this Behaviour has been analysed in previous research, an understanding of Convergence Behaviour facilitated by social media platforms to an effective level of control, is yet to be achieved. This paper examines how Twitter users, converged on the Manchester Bombing 2017. We identified the most impactful Convergence Behaviour archetypes, including those with the highest perceived legitimacy of Convergence i.e. those deemed by the Twitter network, to have a necessary and meaningful role in the crisis. Manual content and social network analyses were conducted on our data by identifying three roles that determine the Twitter users with the highest impact regarding their retweet Behaviour. We determined that Helpers, Mourners and Detectives had the highest impact on crisis communication in this event.

Milad Mirbabaie - One of the best experts on this subject based on the ideXlab platform.

  • Dynamics of Convergence Behaviour in social media crisis communication – a complexity perspective
    Information Technology & People, 2021
    Co-Authors: Milad Mirbabaie, Stefan Stieglitz, Felix Brünker
    Abstract:

    PurposeThe purpose of this study is to investigate communication on Twitter during two unpredicted crises (the Manchester bombings and the Munich shooting) and one natural disaster (Hurricane Harvey). The study contributes to understanding the dynamics of Convergence Behaviour archetypes during crises.Design/methodology/approachThe authors collected Twitter data and analysed approximately 7.5 million relevant cases. The communication was examined using social network analysis techniques and manual content analysis to identify Convergence Behaviour archetypes (CBAs). The dynamics and development of CBAs over time in crisis communication were also investigated.FindingsThe results revealed the dynamics of influential CBAs emerging in specific stages of a crisis situation. The authors derived a conceptual visualisation of Convergence Behaviour in social media crisis communication and introduced the terms hidden and visible network-layer to further understanding of the complexity of crisis communication.Research limitations/implicationsThe results emphasise the importance of well-prepared emergency management agencies and support the following recommendations: (1) continuous and (2) transparent communication during the crisis event as well as (3) informing the public about central information distributors from the start of the crisis are vital.Originality/valueThe study uncovered the dynamics of crisis-affected Behaviour on social media during three cases. It provides a novel perspective that broadens our understanding of complex crisis communication on social media and contributes to existing knowledge of the complexity of crisis communication as well as Convergence Behaviour.

  • Convergence Behaviour of Bystanders: An Analysis of 2016 Munich Shooting Twitter Crisis Communication
    arXiv: Social and Information Networks, 2019
    Co-Authors: Deborah Bunker, Milad Mirbabaie, Stefan Stieglitz
    Abstract:

    While Convergence Behaviour archetypes can explain Behaviour of individuals who actively converge on and participate in crises, less is known about individuals who converge on an event and choose to remain passive i.e. "bystanders". Bystanders are important, because of their proximity to an event and their function as an "eye-witness". To investigate the role of bystanders in crisis communications we analysed Twitter communication generated from the 2016 Munich Shooting event. Our findings revealed the impassive Convergence Behaviour archetype could influence an event as a passive and rational "eye-witness", by gathering and sharing information close to where the event is occurring.

  • Who Sets the Tone? Determining the Impact of Convergence Behaviour Archetypes in Social Media Crisis Communication
    Information Systems Frontiers, 2019
    Co-Authors: Milad Mirbabaie, Deborah Bunker, Stefan Stieglitz, Annika Deubel
    Abstract:

    Convergence Behaviour Archetypes (CBA) describe the Behavioural traits of individuals who spontaneously and collectively move towards emergency situations. If Convergence is not managed effectively, unintended crisis management issues may emerge and lead to an exacerbation of the crisis situation. Social media users express different Behavioural intentions while converging on a crisis. While these Behavioural intentions have been analysed in previous research, an understanding of Convergence Behaviour facilitated by social media use to an effective and smart level of control, is yet to be achieved. Manual content and social network analyses were conducted on our Twitter dataset of the Manchester Bombing 2017 and this analysis identified three dominant Convergence Behaviour archetypes i.e. the Helpers, the Mourners and the Detectives. These archetypes had the highest crisis communications impact regarding their retweet Behaviour. This work provides a better theoretical understanding of Convergence Behaviour archetype influence and impact on crisis communication, for Information Systems research and practice.

  • TDIT - Examining Convergence Behaviour During Crisis Situations in Social Media - A Case Study on the Manchester Bombing 2017
    Smart Working Living and Organising, 2018
    Co-Authors: Milad Mirbabaie, Deborah Bunker, Annika Deubel, Stefan Stieglitz
    Abstract:

    Convergence Behaviour Archetypes (CBA) describe the many different ways that individuals spontaneously and collectively move towards an emergency situation. If this movement is not managed effectively, crisis management issues and problems can emerge and lead to an exacerbation of the crisis situation e.g. panic, Convergence of people and resources towards danger, Convergence of excess and unrequired people and resources etc. Users of social media platforms express different motivations and Behaviours while converging on a crisis. While this Behaviour has been analysed in previous research, an understanding of Convergence Behaviour facilitated by social media platforms to an effective level of control, is yet to be achieved. This paper examines how Twitter users, converged on the Manchester Bombing 2017. We identified the most impactful Convergence Behaviour archetypes, including those with the highest perceived legitimacy of Convergence i.e. those deemed by the Twitter network, to have a necessary and meaningful role in the crisis. Manual content and social network analyses were conducted on our data by identifying three roles that determine the Twitter users with the highest impact regarding their retweet Behaviour. We determined that Helpers, Mourners and Detectives had the highest impact on crisis communication in this event.

  • Examining Convergence Behaviour During Crisis Situations in Social Media - A Case Study on the Manchester Bombing 2017
    2018
    Co-Authors: Milad Mirbabaie, Deborah Bunker, Annika Deubel, Stefan Stieglitz
    Abstract:

    Convergence Behaviour Archetypes (CBA) describe the many different ways that individuals spontaneously and collectively move towards an emergency situation. If this movement is not managed effectively, crisis management issues and problems can emerge and lead to an exacerbation of the crisis situation e.g. panic, Convergence of people and resources towards danger, Convergence of excess and unrequired people and resources etc. Users of social media platforms express different motivations and Behaviours while converging on a crisis. While this Behaviour has been analysed in previous research, an understanding of Convergence Behaviour facilitated by social media platforms to an effective level of control, is yet to be achieved. This paper examines how Twitter users, converged on the Manchester Bombing 2017. We identified the most impactful Convergence Behaviour archetypes, including those with the highest perceived legitimacy of Convergence i.e. those deemed by the Twitter network, to have a necessary and meaningful role in the crisis. Manual content and social network analyses were conducted on our data by identifying three roles that determine the Twitter users with the highest impact regarding their retweet Behaviour. We determined that Helpers, Mourners and Detectives had the highest impact on crisis communication in this event.

Guy Marin - One of the best experts on this subject based on the ideXlab platform.

  • Simultaneous solution algorithms for Eulerian-Eulerian gas-solid flow models: Stability analysis and Convergence Behaviour of a point and a plane solver
    Journal of Computational Physics, 2005
    Co-Authors: Juray De Wilde, Jan Vierendeels, Geraldine Heynderickx, Guy Marin
    Abstract:

    Simultaneous solution algorithms for Eulerian-Eulerian gas-solid flow models are presented and their stability analyzed. The integration algorithms are based on dual-time stepping with fourth-order Runge-Kutta in pseudo-time. The domain is solved point or plane wise. The discretization of the inviscid terms is based on a low-Mach limit of the multi-phase preconditioned advection upstream splitting method (MP-AUSMP). The numerical stability of the simultaneous solution algorithms is analyzed in 2D with the Fourier method. Stability results are compared with the Convergence Behaviour of 3D riser simulations. The impact of the grid aspect ratio, preconditioning, artificial dissipation, and the treatment of the source terms is investigated. A particular advantage of the simultaneous solution algorithms is that they allow a fully implicit treatment of the source terms which are of crucial importance for the Eulerian-Eulerian gas-solid flow models and their solution. The numerical stability of the optimal simultaneous solution algorithm is analyzed for different solids volume fractions and gas-solid slip velocities. Furthermore, the effect of the grid resolution on the Convergence Behaviour and the simulation results is investigated. Finally, simulations of the bottom zone of a pilot-scale riser with a side solids inlet are experimentally validated.

  • Preconditioning for the simultaneous solution of gas-solid flows
    2005
    Co-Authors: Juray De Wilde, Geraldine Heynderickx, Edward Baudrez, Guy Marin
    Abstract:

    For single phase flows, the introduction of preconditioning allowed the use of simultaneous solution algorithms for low-Mach calculations. For gas-solid flows, preconditioned simultaneous solution algorithms have only been introduced recently. Although simultaneous solution algorithms have clear advantages over sequential solution algorithms, e.g. a fully implicit treatment of the source terms, the Convergence Behaviour obtained for gas-solid flows is poor compared to the Convergence Behaviour obtained for single phase flows.

Lajos Hanzo - One of the best experts on this subject based on the ideXlab platform.

  • Convergence Behaviour of iteratively decoded short block codes in h 264 joint source and channel decoding
    Vehicular Technology Conference, 2009
    Co-Authors: Lajos Hanzo
    Abstract:

    We propose a novel class of Short Block Codes (SBCs) designed for guaranteed Convergence to an infinitesimally low Bit Error Ratio (BER), which relies on the joint optimisation of soft-bit assisted iterative source and channel decoding. An iterative detection aided combination of SBC assisted Soft-Bit Source Decoding (SBSD) and a rate-1 precoder was used to evaluate the attainable performance of the proposed scheme for transmission of Data-Partitioned (DP) H.264 source coded video over correlated narrowband Rayleigh fading channels. Addition- ally, we demonstrated the effects of different SBCs having diverse minimum Hamming distances (dH,min) but identical coding rates on both the overall BER performance as well as on the objective video quality expressed in terms of the Peak Signal-to-Noise Ratio (PSNR). The Convergence Behaviour of the iterative decoding scheme using SBCs as a function of dH,min is analysed by utilising extrinsic information transfer (EXIT) charts. Explicitly, our experimental results show that the proposed error protection scheme using SBCs associated with dH,min =6 outperforms the identical-code-rate SBCs having dH,min =3 by about 3 dB at the PSNR degradation point of 1 dB. Additionally, an Eb/N0 gain of 27 dB is attained using iterative soft-bit source and channel decoding with the aid of rate- 1 SBCs relative to the identical-rate benchmarker. I. MOTIVATION AND BACKGROUND

  • VTC Spring - Convergence Behaviour of Iteratively Decoded Short Block-Codes in H.264 Joint Source and Channel Decoding
    VTC Spring 2009 - IEEE 69th Vehicular Technology Conference, 2009
    Co-Authors: Nasruminallah, Lajos Hanzo
    Abstract:

    We propose a novel class of Short Block Codes (SBCs) designed for guaranteed Convergence to an infinitesimally low Bit Error Ratio (BER), which relies on the joint optimisation of soft-bit assisted iterative source and channel decoding. An iterative detection aided combination of SBC assisted Soft-Bit Source Decoding (SBSD) and a rate-1 precoder was used to evaluate the attainable performance of the proposed scheme for transmission of Data-Partitioned (DP) H.264 source coded video over correlated narrowband Rayleigh fading channels. Addition- ally, we demonstrated the effects of different SBCs having diverse minimum Hamming distances (dH,min) but identical coding rates on both the overall BER performance as well as on the objective video quality expressed in terms of the Peak Signal-to-Noise Ratio (PSNR). The Convergence Behaviour of the iterative decoding scheme using SBCs as a function of dH,min is analysed by utilising extrinsic information transfer (EXIT) charts. Explicitly, our experimental results show that the proposed error protection scheme using SBCs associated with dH,min =6 outperforms the identical-code-rate SBCs having dH,min =3 by about 3 dB at the PSNR degradation point of 1 dB. Additionally, an Eb/N0 gain of 27 dB is attained using iterative soft-bit source and channel decoding with the aid of rate- 1 SBCs relative to the identical-rate benchmarker. I. MOTIVATION AND BACKGROUND

Juray De Wilde - One of the best experts on this subject based on the ideXlab platform.

  • Simultaneous solution algorithms for Eulerian-Eulerian gas-solid flow models: Stability analysis and Convergence Behaviour of a point and a plane solver
    Journal of Computational Physics, 2005
    Co-Authors: Juray De Wilde, Jan Vierendeels, Geraldine Heynderickx, Guy Marin
    Abstract:

    Simultaneous solution algorithms for Eulerian-Eulerian gas-solid flow models are presented and their stability analyzed. The integration algorithms are based on dual-time stepping with fourth-order Runge-Kutta in pseudo-time. The domain is solved point or plane wise. The discretization of the inviscid terms is based on a low-Mach limit of the multi-phase preconditioned advection upstream splitting method (MP-AUSMP). The numerical stability of the simultaneous solution algorithms is analyzed in 2D with the Fourier method. Stability results are compared with the Convergence Behaviour of 3D riser simulations. The impact of the grid aspect ratio, preconditioning, artificial dissipation, and the treatment of the source terms is investigated. A particular advantage of the simultaneous solution algorithms is that they allow a fully implicit treatment of the source terms which are of crucial importance for the Eulerian-Eulerian gas-solid flow models and their solution. The numerical stability of the optimal simultaneous solution algorithm is analyzed for different solids volume fractions and gas-solid slip velocities. Furthermore, the effect of the grid resolution on the Convergence Behaviour and the simulation results is investigated. Finally, simulations of the bottom zone of a pilot-scale riser with a side solids inlet are experimentally validated.

  • Preconditioning for the simultaneous solution of gas-solid flows
    2005
    Co-Authors: Juray De Wilde, Geraldine Heynderickx, Edward Baudrez, Guy Marin
    Abstract:

    For single phase flows, the introduction of preconditioning allowed the use of simultaneous solution algorithms for low-Mach calculations. For gas-solid flows, preconditioned simultaneous solution algorithms have only been introduced recently. Although simultaneous solution algorithms have clear advantages over sequential solution algorithms, e.g. a fully implicit treatment of the source terms, the Convergence Behaviour obtained for gas-solid flows is poor compared to the Convergence Behaviour obtained for single phase flows.