Open Access

A new goodness-of-fit test for the composite null hypothesis that data originate from a geometric Brownian motion is studied in the functional data setting. This is equivalent to testing if the data are from a scaled Brownian motion with linear drift. Critical values for the test are obtained, ensuring that the specified significance level is achieved in finite samples. The asymptotic behavior of the test statistic under the null distribution and alternatives is studied, and it is also demonstrated that the test is consistent. Furthermore, the proposed approach offers advantages in terms of fast and simple implementation. A comprehensive simulation study shows that the power of the new test compares favorably to that of existing methods. A key application is the assessment of financial time series for the suitability of the Black-Scholes model. Examples relating to various stock and interest rate time series are presented in order to illustrate the proposed test.

This study examines the evolving power dynamics within servitization ecosystems, and especially the role of AI platform providers in them. Drawing on French and Raven’s (1959) bases of power, as well as resource dependence theory, we propose a conceptual model that shows how AI providers centralize control and reshape power relations. As AI integrates into servitization, providers leverage informational and expert power through data management and algorithmic expertise, alongside legitimate and referent power, to influence behaviours, promote risk-taking, foster dependency, and establish themselves as central authorities setting standards and norms. They further exploit coercive and reward power to impose conditions and offer incentives that deepen platform reliance, ultimately dominating the ecosystem and establishing a quasi-monopolistic position. We enrich the servitization literature by challenging the prevailing view that AI adoption benefits downstream manufacturers.

Conditional excess distribution modelling is a widely used technique, in financial and insurance mathematics or survival analysis, for instance. Classical theory considers the thresholds as fixed values. In contrast, the use of empirical quantiles as thresholds offers advantages with respect to the design of the statistical experiment. Either way, the modeller is in a non-standard situation and runs in the risk of improper usage of statistical procedures. From both points of view, statistical planning and inference, a detailed discussion is requested. For this purpose, we treat both methods and demonstrate the necessity taking into account the characteristics of the approaches in practice. In detail, we derive general statements for empirical processes related to the conditional excess distribution in both situations. As examples, estimating the mean excess and the conditional Value-at-Risk are given. We apply our findings for the testing problems of goodness-of-fit and homogeneity for the conditional excess distribution and obtain new results of outstanding interest.

Masonry infills are frequently employed as both outer and inner partitions in reinforced concrete (RC) frame structures due to their outstanding characteristics in terms of energy efficiency, fire resistance and sound isolation. However, common construction practice typically involves the mortar connection between masonry infills and RC frames. For this reason, the unforeseen frame-infill interaction takes part under seismic loading, which leads to severe and uncontrollable damage to masonry infills. This interaction also causes damage or even the collapse of the RC frames and thus of the whole structures. The poor performance of infilled RC frame structures in recent earthquake events is a strong motivation for the development of innovative engineering solutions, which aim to mitigate the detrimental effects of frame-infill interaction. This article introduces an innovative decoupling system founded on the concept of decoupling the RC frame from the masonry infill. The decoupling is achieved by inserting elastomeric material between the masonry infill and RC frame. The properly designed decoupling system allows infill activation only at high in-plane drifts. Simultaneously, it provides boundary conditions for seismic loads acting perpendicular to the infill plane. Firstly, the article explains the design of the masonry infill with the decoupling system and its installation. Afterwards, the results of small specimen tests carried out to determine the load-bearing capacity of the decoupling system are presented. Furthermore, the article discusses the findings of an extensive experimental campaign conducted on nine real-size RC frames with decoupled infills subjected to separate and combined in-plane and out-of-plane loadings. In addition to different loading types, various infill configurations are considered – solid infill, infill with centric window, and infill with centric door opening. Finally, the experimental results of RC frames with decoupled infills are compared with the experimental results of traditionally infilled RC frames, which were tested within the framework of the same project. The thorough evaluation and comparison of the experimental findings demonstrate the significant improvement of seismic performance of infilled RC frames if the decoupling system is applied.