Browsing by UP Author "De Waal, Alta"

Browsing by UP Author "De Waal, Alta"

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  • Activity-based travel demand generation using Bayesian networks 
    Joubert, Johannes Willem; De Waal, Alta (Elsevier, 2020-11)
    While activity-based travel demand generation has improved over the last few decades, the behavioural richness and intuitive interpretation remain challenging. This paper argues that it is essential to understand why people ...
  • Autoencoding variational Bayes for latent Dirichlet allocation 
    Wolpe, Zach; De Waal, Alta (CEUR Workshop Proceedings, 2019)
    Many posterior distributions take intractable forms and thus require variational inference where analytical solutions cannot be found. Variational Inference and Monte Carlo Markov Chains (MCMC) are es- tablished mechanism ...
  • Evaluation of a pure-strategy Stackelberg game for wildlife security in a geospatial framework 
    Kirkland, Lisa-Ann; De Waal, Alta; De Villiers, Johan Pieter (Springer, 2020-12)
    Current research on wildlife security games has minimal focus on performance evaluation. The performance of the rangers is evaluated by assessing their game utility, sometimes in comparison with their maximin utility, and ...
  • An expert-driven causal model of the rhino poaching problem 
    Koen, Hildegarde; De Villiers, Johan Pieter; Roodt, Henk; De Waal, Alta (Elsevier, 2017-03)
    A significant challenge in ecological modelling is the lack of complete sets of high-quality data. This is especially true in the rhino poaching problem where data is incomplete. Although there are many poaching attacks, ...
  • A Gamma-Poisson mixture topic model for short text 
    Mazarura, Jocelyn; De Waal, Alta; De Villiers, Johan Pieter (Hindawi Publishing, 2020-04-29)
    Most topic models are constructed under the assumption that documents follow a multinomial distribution. The Poisson distribution is an alternative distribution to describe the probability of count data. For topic modelling, ...
  • Modelling bimodal data using a multivariate triangular-linked distribution 
    De Waal, Daan; Harris, Tristan; De Waal, Alta; Mazarura, Jocelyn Rangarirai (MDPI, 2022-07-06)
    Bimodal distributions have rarely been studied although they appear frequently in datasets. We develop a novel bimodal distribution based on the triangular distribution and then expand it to the multivariate case using ...
  • Modifying copulas for improved dependence modelling 
    Le Roux, Colette; De Waal, Alta (CEUR Workshop Proceedings, 2019)
    In 2007 and 2008, underestimation of correlations and risks, as well as the misuse of dependence models, lead to the financial crisis. This highlighted the need to improve dependence modelling through both the correlation ...
  • Quantifying rehabilitation risks for surface-strip coal mines using a soil compaction Bayesian network in South Africa and Australia : to demonstrate the R(2)AIN Framework 
    Weyer, Vanessa Derryn; De Waal, Alta; Lechner, Alex M.; Unger, Corinne J.; O'Connor, Tim G.; Baumgartl, Thomas; Schulze, Roland; Truter, Wayne Frederick (Wiley, 2019-03)
    Environmental information is acquired and assessed during the environmental impact assessment process for surface‐strip coal mine approval. However, integrating these data and quantifying rehabilitation risk using a holistic ...
  • A taxonomy of explainable Bayesian networks 
    Derks, Iena Petronella; De Waal, Alta (Springer, 2020-12)
    Artificial Intelligence (AI), and in particular, the explainability thereof, has gained phenomenal attention over the last few years. Whilst we usually do not question the decision-making process of these systems in ...
  • A two-stage contagious Naive Bayes classifier for detecting sociolinguistic features in text 
    Derks, Iena Petronella; De Waal, Alta (CEUR Workshop Proceedings, 2019)
    Online platforms allow users to masquerade themselves; making virtual interactions anonymous or misleading recipients of the interactions. It also facilitates an environment for cybercrimes, allowing users to take advantage ...