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Reply to comment on ‘The polarizability of a confined atomic system: an application of the Dalgarno-Lewis method’
( 2023 ) Antão, T. V.C.; Peres, N. M. R.
[Excerpt] The purpose of the original paper by Antão and Peres [1] is to show that the polarisability of an atomic system, when in the vicinity of a surface, can be used as a nanometric ruler, emphasizing the pedagogical value of Dalgarno–Lewis perturbation theory. Indeed this is stated in the abstract of [1] ‘...creating the possibility of using this quantity as a nanometric ruler’. That this is true, is evident from both figures 3 and 5 of [1], where the distance to the surface determines the overall appearance of both the static (figure 3 of [1]) and dynamic (figure 5 of [1]) polarizability. Maize and Smetanka do not question the validity of these results, simply stressing that they are off by an overall factor of 2, which we acknowledge. As well understood, an overall factor of 2 cannot change the physical properties of the problem and therefore the qualitative validity of the results. [...]
Preservation and protection of cultural heritage: vibration monitoring and seismic vulnerability of the ruins of Carmo Convent (Lisbon)
( 2024 ) Mendes, N.; Bianchini, Nicoletta; Karanikoloudis, Georgios; Blyth, Anna; Scacco, Jacopo; Flores Salazar, Luis Gerardo; Cullimore, Cassie; Jain, Lavina
Preservation of cultural heritage sites is of paramount importance. The ruins of Carmo Convent in Lisbon stand as a poignant reminder of the city’s rich history, but challenges regarding structural integrity and safety are present in a highly populated and touristic area. In this paper, a comprehensive study of the Carmo Convent is presented, focused on non-destructive testing (NDT), structural health monitoring (SHM) and numerical modelling. Given its state of ruin and historical relevance, the study relied heavily on NDT. Additionally, a metro line passing underneath the convent raised concerns regarding potential hazards from induced vibrations. Thus, metro vibration monitoring (MVM) was implemented to assess the impact of induced vibrations on the structure. One of the challenges was the scarcity of standards specific to historic structures. However, through a combination of finite element method (FEM) and discrete element method (DEM) numerical modelling, valuable insights into the current condition of the structure were obtained. MVM revealed that the maximum velocity induced by metro activities remained within safe limits, indicating minimal impact. These results not only provide crucial information on structural preservation but also empower stakeholders to make informed decisions regarding the implementation of protective measures.
Optimising sensor placement in heritage buildings: A comparison of model-based and data-driven approaches
( 2025 ) Chaves, Estefanía; Barontini, Alberto; Mendes, N.; Compán, Víctor
The long-term preservation of heritage structures relies on effective Structural Health Monitoring (SHM) systems, where sensor placement is key to ensuring early damage detection and guiding conservation efforts. Optimal Sensor Placement (OSP) methods offer a systematic framework to identify efficient sensor configurations, yet their application in historical buildings remains limited. Typically, OSP is driven by numerical models; however, in the context of heritage structures, these models are often affected by substantial uncertainties due to irregular geometries, heterogeneous materials, and unknown boundary conditions. In this scenario, data-driven approaches become particularly attractive as they eliminate the need for potentially unreliable models by relying directly on experimentally identified dynamic properties. This study investigates how the choice of input data influences OSP outcomes, using the Church of Santa Ana in Seville, Spain, as a representative case. Three data sources are considered: an uncalibrated numerical model, a calibrated model, and a data-driven set of modal parameters. Several OSP methods are implemented and systematically compared. The results underscore the decisive impact of the input data on the optimisation process. Although calibrated models may improve certain modal parameters, they do not necessarily translate into better sensor configurations. This highlights the potential of data-driven strategies to enhance the robustness and applicability of SHM systems in the complex and uncertain context of heritage buildings.
