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Publication Management of time and cost contingencies in construction projects: a contractos perspective(VGTU Press, 2018-03-01) Ortiz González, José Ignacio; Molenaar, KeithThe management of threats and opportunities plays a key-role in enhancing project performance. However, there is a gap in literature concerning how general contractors manage threats and opportunities in construction projects, in particular in the use of time and cost contingencies. This research partially addresses this gap through a case study of two large Spanish construction companies. The research presented two key factors determining how the contractors analyzed manage time and cost contingencies: project objectives and existing mistrust among the contractor's team members. The research also found that managers use time and cost contingencies not only to manage threats, but also as tools for managing opportunities, thereby providing insight into a previously undescribed form of contingency: the negative contingency. the research results enable a better understanding of the actual behavior of general contractors, which contributes to paving the way for developing enhanced methods for contingencies management.Publication Optimising the preparedness capacity of enterprise resilience using mathematical programming(MDPI, 2020-09) Sanchis, Raquel; Durán Heras, Alfonso; Poler, Raul; Agencia Estatal de Investigación (España)In today's volatile business arena, companies need to be resilient to deal with the unexpected. One of the main pillars of enterprise resilience is the capacity to anticipate, prevent and prepare in advance for disruptions. From this perspective, the paper proposes a mixed-integer linear programming (MILP) model for optimising preparedness capacity. Based on the proposed reference framework for enterprise resilience enhancement, the MILP optimises the activation of preventive actions to reduce proneness to disruption. To do so, the objective function minimizes the sum of the annual expected cost of disruptive events after implementing preventive actions and the annual cost of such actions. Moreover, the algorithm includes a constraint capping the investment in preventive actions and an attenuation formula to deal with the joint savings produced by the activation of two or more preventive actions on the same disruptive event. The management and business rationale for proposing the MILP approach is to keep it as simple and comprehensible as possible so that it does not require highly mathematically skilled personnel, thus allowing top managers at enterprises of any size to apply it effortlessly. Finally, a real pilot case study was performed to validate the mathematical formulation.Publication Reuse of components between virtual, b-learning and face-to-face courses. A case study in management information systems(Universidad de Oviedo, 2021-04-16) Castilla Alcalá, Guillermo; Durán Heras, Alfonso; Ortiz González, José IgnacioThe integration between virtual and face-to-face (ftf) classroom learning is increasing. This is leading to an increase in mixed learning or blended-learning. Due to this growing trend there is a need to reuse course components between these strategies in the interest of efficiency. Additionally, the wide availability of open source software facilitates the construction of learning activities without incurring in licences expenses; activities which can then also be included in other courses. The reuse of these learning activities between virtual, ftf and mixed education may require significant efforts to adapt them if this possibility has not been considered in advance. Adoption of certain architectures and methodologies, that facilitate flexibility and reuse, can simplify this process, as proposed in this paper. A case study is presented on reusing learning activities on Management Information Systems (MIS) developed for either ftf instruction or for an edX MOOC, that are reused in courses in various learning modes: online, blended learning and face-to-face.Publication Undershoot and order quantity probability distributions in periodic review, reorder point, order-up-to-level inventory systems with continuous demand(Elsevier, 2021-03) Gutiérrez Fernández, Miguel; Rivera Riquelme, Francisco Antonio; Ministerio de Ciencia, Innovación y Universidades (España)The undershoot of the reorder point in the periodic review, order-up-to-level (R, s, S) inventory system is known to follow a complex probability distribution which depends on the value of S-s (Δ) and the distribution of the demand during the review interval (R). We focus on the continuous demand case with full backlogging and variable lead-time. For this case, a generic formulation of the undershoot probability density function (p.d.f.) is developed. The order quantity probability distribution in (R, s, S) systems is the same as the undershoot probability distribution with a shift of Δ in the random variable. Therefore, the latter opens the possibility of calculating valuable managerial information such as the expected average order quantity, its standard deviation, and the probability that the order quantity is lower than or exceeds a predetermined value. Based on the proposed formulation, we derive an analytical expression of the undershoot p.d.f. (and hence the order quantity p.d.f.) for the case of gamma distributed demand, as well as a tractable approximation for the normal distributed demand. Both expressions are shown to be dependent upon two nondimensional parameters, Δ/μR and the coefficient of variation, with the mean demand during the review interval (μR) acting as a scale parameter. We thus define a nondimensional undershoot p.d.f. (NUPDF). The relevance of full nondimensionalization stems from the fact that gamma and normal NUPDF analyses can be scaled to any case of gamma and normal distributed demands. Although we focus on the inventory management viewpoint, the results for the gamma distributed case can be directly adapted for use in any renewal process.