On the Nature and Types of Anomalies: A Review

Anomalies are occurrences in a dataset that are in some way unusual and do not fit the general patterns. The concept of the anomaly is generally ill-defined and perceived as vague and domain-dependent. Moreover, despite some 250 years of publications on the topic, no comprehensive and concrete overviews of the different types of anomalies have hitherto been published. By means of an extensive literature review this study therefore offers the first theoretically principled and domain-independent typology of data anomalies, and presents a full overview of anomaly types and subtypes. To concretely define the concept of the anomaly and its different manifestations, the typology employs five dimensions: data type, cardinality of relationship, anomaly level, data structure and data distribution. These fundamental and data-centric dimensions naturally yield 3 broad groups, 9 basic types and 61 subtypes of anomalies. The typology facilitates the evaluation of the functional capabilities of anomaly detection algorithms, contributes to explainable data science, and provides insights into relevant topics such as local versus global anomalies.Comment: 38 pages (30 pages content), 10 figures, 3 tables. Preprint; review comments will be appreciated. Improvements in version 2: Explicit mention of fifth anomaly dimension; Added section on explainable anomaly detection; Added section on variations on the anomaly concept; Various minor additions and improvement

Damage-imperfection indicators for the assessment of multi-leaf masonry walls under different conditions

The complexity of multi-leaf masonry walls suggests further researches on the dy- namic behaviour mainly characterized by incoherent response between the different layers. The intrinsic discontinuity and the manufacturing imperfections are amplified by the incre- mental damage that triggers different failure mechanisms that affect the dynamic parameters, such as modal shapes, frequencies and damping ratios. The dynamic identification with out- put only methodology has been proposed in this work on different multi-leaf masonry walls subjected to uniaxial compressive load. The responses of full infill, damaged infill and strengthened infill masonry panels with different widespread damage have been recorded. The evolution of the damage scenario changes the modal shapes, the related frequencies and the damping ratios that through the comparison with the data of the initial conditions can de- tect the anomalies and then the intrinsic vulnerabilities. Through the curvature modal shape methods and the structural irregularity indices applied to different phases, it was possible evaluate the imperfection and the induced damage entity

Characterization of a Pre-Trajan wall by integrated geophysical methods

The purpose of this study was to characterize a pre-Trajan mosaic-decorated wall structure located beneath the Cryptoporticus of the 'Baths of Trajan' complex in Rome. The surveyed wall is 15m long, 0.9m wide and 3 to 5m high. Ground penetrating radar (GPR) and P-wave seismic refraction tomography profiles were used to reconstruct the wall's inner structure, generate a map of the fractures and to evaluate the seismic velocities of the building materials. The wall was surveyed with horizontally and vertically dense GPR profiles and two seismic lines. The seismic lines and GPR profiles were capable of detecting a discontinuity between brick and travertine materials that compose the wall. The combined interpretation of the two non-invasive techniques allowed us to locate weak zones and fractures. This rapid, non-destructive and multi-parametric approach has proved to be effective for characterizing the current status of the wall and the results will be used by archaeologists to evaluate the wall's integrity and to preserve the structure in the future archaeological excavations

Calculation of the Risk of Lawsuits over Construction Flaws in Flat Roofs

In order to achieve sustainability objectives in the use of a building, its elements’ operating problems should be minimized. From this premise, a total of 497 cases related to construction flaws in flat roofs were analyzed in this research. A matrix was developed indicating the risk of lawsuits by owners according to the degree of nuisance resulting from the construction flaws studied, their technical importance, and the type of pathological origin. Based on these factors, it is possible to predict a greater or lesser probability of an owner filing a lawsuit—risk factor (F). A wide range was found for this probability, with the largest value being 865 times greater than the smallest value. The value of F was divided into 5 categories to classify the diverse results obtained and determine the number of cases and interrelations ascribed to each category. Additionally, the level of presence of said cases was calculated through the analysis of 3 di erent demographic aspects, it being noted that a greater purchasing power and a higher concentration of urban population lead to more stringent requirements and, subsequently, to a greater number of lawsuits. With all these results, building quality can be improved while resulting in greater constructive-financial sustainability and in a reduction of the economic resources required of society (fewer lawsuits and associated human resources)

Data analytics for smart buildings: a classification method for anomaly detection for measured data

Abstract Data generated by the increasingly frequent use of sensors in housing provide the opportunity to monitor, manage and optimize the energy consumption of a building and the user comfort. These data are often strewn with rare or anomalous events, considered as anomalies (or outliers), that must be detected and ultimately corrected in order to improve the data quality. However, many approaches are used or might be used (for the most recent ones) to achieve this purpose. This paper proposes a classification methodology of anomaly detection techniques applied to building measurements. This classification methodology uses a well-suited anomaly typology and measurement typology in order to provide, in the future, a classification of the most adapted anomaly detection techniques for different types of building measurements, anomalies and needs

Assessment of seismic performance of adobe structures in Pakistan and Portugal

Adobe buildings exist in different parts of the world. The construction of these buildings can be carried out economically, using locally available materials and skills that do not require use of modern machinery. Therefore, adobe buildings provide an economic housing option. The construction of adobe structures is carried out based on traditional construction practices which vary from region to region. This paper presents the results of a study which was conducted to study the construction practices of adobe buildings in Pakistan and Portugal in the context of their seismic vulnerability. The adobe buildings in both these countries were found to be subjected to seismic hazard levels which, although is low in some regions, may cause significant damages. Lack of essential elements or details for the adequate seismic performance was found in the adobe buildings in both regions