University of Tarapacá

We investigate effects of longitudinally varying nonlinearity on periodically distributed amplification systems in optical fibres. Emphasis is made on configurations in which the nonlinear coefficient exponentially grows or decays along the propagation distance, while the group-velocity-dispersion (GVD) coefficient is held constant. Such systems are of practical relevance to the design of highly efficient nonlinear devices, including broadband light sources and advanced amplification schemes, where precise management of the interplay between the GVD, nonlinearity, and gain is essential. Adopting the known generic integrability condition, we derive exact analytical expressions for the evolution of the optical field in the presence of the tailored nonlinearity profiles and periodically distributed gain. The resulting periodic wavetrain solutions and their long-wave limit in the form of bright and dark solitons provide insight into the controlled enhancement or suppression of nonlinear effects under realistic amplification conditions. The robustness of these solutions is examined by introducing finite perturbations and directly evaluating their effects on the corresponding intensity profiles. The structural stability of solutions against deviations from the integrability condition is demonstrated too. Outcomes of this study contribute to a deeper understanding of the nonlinear pulse dynamics in engineered gain-managed fibres and offer guidance for the development of novel optical systems, where the spatial distribution of the nonlinearity is exploited to optimise the performance.

Resistive Plate Chambers (RPCs) are widely employed in high-energy physics experiments due to their excellent timing resolution and high detection efficiency. Conventional RPC operation relies on freon-based gas mixtures having high Global Warming Potential (GWP), contributing significantly to greenhouse gas emissions. In this work, the performance of a single-gap glass RPC detector (30 cm & times; 30 cm) is studied using the standard gas mixture (C2H2F4 95%, i-C4H10 4.5%, SF6 0.5%) and eco-friendly alternatives based on CO2 and HFO gases. The detector was tested using cosmic muons, and its performance was evaluated in terms of efficiency, current-voltage characteristics, and timing resolution. The results show that eco-friendly gas mixtures achieve stable detector operation with high efficiency and only marginal degradation in timing performance, demonstrating their potential application to environmentally sustainable RPC operation.

Remaining useful life (RUL) prediction under time-varying operating conditions is a critical yet challenging problem. In such scenarios, degradation trends and operating condition variations are strongly coupled in observed signals, making it difficult for conventional methods to separate these two types of features. To address this issue, this paper proposes a dual dynamic prior disentangling network for RUL prediction under time-varying operating conditions. The proposed method disentangles raw vibration signals into degradation features and operating-condition features by minimizing their mutual information. Meanwhile, dynamic variational priors are designed for both types of features, together with separate invertible transition networks to enable the tractable probabilistic modeling. Specifically, a temporal dynamic prior is designed for degradation features to capture the long-term evolution, while a piecewise dynamic prior with switching indicators is used for operating-condition features to model stationery and transition stages of operating modes. Based on the derived variational bounds, the model is optimized in an end-to-end manner for feature disentanglement and RUL prediction. Experiments on a self-collected full-life-cycle bearing dataset under time-varying operating conditions demonstrate the effectiveness of the proposed method. Specifically, the proposed method achieves an average RMSE of 0.114 and an average Score1 of 0.728, representing a reduction of approximately 24 % and an improvement of approximately 7.7 % compared to the suboptimal baseline, respectively. Furthermore, additional experiments on real wind turbine bearings and public datasets fully validate the superiority and practical applicability of the proposed method.

Gaseous detectors are key components of particle detection in High Energy Physics experiments. The GEM is one such detector being used in HEP experiments due to its good timing and spatial resolution, and radiation tolerance. The optimal performance of gaseous detector depends on the choice of gases being used as ionising medium. Fluorine (F)-based gases, specially CF4 are commonly used in particle detectors as it leads to time resolution of a few nanoseconds(ns). But due to environmental concerns, F-based gases are no longer considered appropriate for detectors. As a result, there is need to find environment friendly alternatives while maintaining the performance of the detector. In this direction, we have studied the possibility of using HFO as a replacement for CF4 in Ar/CO2 based gas mixture in GEM detectors. We performed this study to evaluate the gain and timing resolution of the GEM detectors. The timing resolution of GEM detectors with only Ar/CO2 mixtures is around 10 ns. In our study, we evaluate the possibility of improving the timing resolution with the use of HFO.

Large dams have resurged in recent decades both to meet growing energy demand and to mitigate climate change effects. Historically, they have been associated with the exercise of State power, nation-building, and territorial control. In Chile, where water access and control are shaped by market mechanisms, the study of large dams requires an approach that accounts for their inherently political nature. This article presents a historical analysis of large dam development in Chile employing the framework of technological hydroscapes. We place large dams as an analytical node through which three periods can be identified, each reflecting a particular mode of governance: private investment (1830–1928), State development (1928–1973), and neoliberalism (1973-present). The period-based examination connects global discourses and trends with the national development of large dams. The broader analysis captures territorial and governance transformations. The findings illustrate the evolution of the national technological hydroscape, providing new insights into the changing role of the State. While water privatisation has been central for the consolidation of the neoliberal programme, our analysis shows that State control over irrigation projects has also been central for the commodification of water and water markets functioning. Furthermore, the privatisation of energy development alongside the continued State involvement in irrigation projects has produced a differentiated territorialisation of private and State power across the country. Consequently, the role of the State varies according to the purpose of large dam projects, ranging from developer in irrigation projects, as mediator between private actors and local communities in hydropower development, and a hybrid role for concessioned projects.