Zoe Paraskevopoulou, Anja Petković Komel, Sophie Rain
et al.
This technical report contains the formal definitions and metatheory for the act specification and verification language. It documents the syntax, the operational pointer semantics, the type system and the main metatheoretic results (type-safety).
This paper develops a semi-analytical solution for pile penetration in natural soft clays using the strain path method (SPM). The stress-strain behavior of soils is characterized by the S-CLAY1S model, which can capture the anisotropic evolution and destructuring nature of soft clays. By integrating the S-CLAY1S model into the theoretical framework of the SPM, a set of ordinary differential equations is formulated with respect to the vertical coordinate of soil particles. The distribution of excess pore water pressure (EPWP) following pile installation is approximated through one-dimensional (1D) radial integration around the pile shaft. The distribution of stresses and EPWP, along with the evolution of fabric anisotropy within the soil surrounding the pile, is presented to illustrate the response of pile penetration in natural soft clays. The proposed solution is validated against existing theoretical solutions using the SPM and cavity expansion method (CEM), along with experimental data. The findings demonstrate that the SPM reveals lower radial effective stresses and EPWP at the pile shaft than that of CEM. Pile penetration alters the soil's anisotropic properties, inducing rotational hardening and affecting post-installation stress distribution. Soil destructuration eliminates bonding among particles near the pile, resulting in a complete disruption of soil structure at the pile surface, which is particularly pronounced for higher initial soil structure ratios. Minimal variation was observed in the three principal stresses and shear stress on the cone side surface as the angle increased from 18° to 60°, except for a slight reduction in EPWP.
Engineering geology. Rock mechanics. Soil mechanics. Underground construction
Asaad M. Armanuos, Martina Zeleňáková, Mohamed Kamel Elshaarawy
Abstract Reliable prediction of SWI is essential for protecting coastal groundwater. In this study, the SWI wedge length in a sloping coastal aquifer controlled by groundwater abstraction and a fractured underground dam is estimated. To achieve this, a dataset consisting of eight dimensionless inputs, derived from prior SEAWAT numerical scenarios, was used to train six machine learning models (linear, nonlinear, and ensemble) to predict the relative SWI wedge length (L/H). First, the dataset underwent thorough examination using hypothesis testing, multicollinearity analysis, and correlation analysis to assess the significance of predictors, their interdependencies, and their relationships with L/H. Specifically, statistical tests, including ANOVA and Z-tests, were employed to identify the key predictors. Furthermore, multicollinearity was assessed using the Variance Inflation Factor (VIF), which helped identify potential redundancies. Subsequently, a cosine amplitude sensitivity analysis was used to quantify the relative influence of each input on L/H. In addition, Bayesian optimization was applied to fine-tune the hyperparameters of each model for optimal performance. The performance of the models was then evaluated using 10-fold cross-validation, regression metrics, and external validation on independent numerical scenarios from the Akrotiri coastal aquifer (Zakaki, Cyprus). Additionally, explainable ML techniques viz Shapley-Additive-Explanations (SHAP) and Partial-Dependence-Plots (PDP), were used to interpret model behavior. Results showed that the ensemble models outperformed alternatives. Among them, the XGB model provided the most consistent accuracy during the testing stage, yielding R2=0.9978, RMSE=0.216, MAE=0.058, and MARE=0.098, while also maintaining strong training performance with RMSE=0.037. Moreover, independent validation against the Akrotiri coastal aquifer confirmed high fidelity and generalizability, with R2=0.997 and RMSE=0.157. The SHAP and PDP analyses revealed that the relative recharge well rate was the dominant predictor, followed by relative fracture height, with relative fracture diameter and relative well distance having significant roles. Finally, a lightweight desktop and web graphical-user-interface (GUI) was developed, enabling rapid, user-friendly prediction of L/H. In conclusion, this study demonstrates that data-driven models can closely replicate physics-based behavior, providing a powerful tool for SWI management and decision-making in coastal aquifers.
Technical debt refers to the trade-offs between code quality and faster delivery, impacting future development with increased complexity, bugs, and costs. This study empirically analyzes the additional work effort caused by technical debt in software projects, focusing on feature implementations. I explore how delaying technical debt repayment through refactoring influences long-term work effort. Using data from open-source and enterprise projects, I correlate technical debt with practical work effort, drawing from issue trackers and version control systems. Our goal is to provide a framework for managing technical debt, aiding developers, project managers, and stakeholders in understanding and mitigating its impact on productivity and costs.
Markowski Jaroslaw, Jesionek Krzysztof, Iliev Iliya
et al.
The development of electric power systems is oriented toward increasing the share of electricity generated from renewable energy sources. These actions lead to the destabilization of the power grid, necessitating the implementation of stabilizing measures such as the temporary disconnection of renewable energy installations, the construction of energy storage systems, and the modernization of thermal energy sources. Modernization changes in electric power systems require significant financial investments and long implementation timelines. As a result, energy distributors are forced to make capital investments, which translate into high energy prices for consumers. For this reason, many companies, in optimizing the cost of their business operations, consider the possibility of operating within so- called isolated energy islands. Typically, this involves isolating the internal power network to supply a portion of the company’s production activities. This approach entails defining an internal power supply area and implementing an energy generation system in the form of a genset – a combustion engine combined with an electric generator. Such a system must ensure frequency stability within the isolated electrical network and provide the required amount of energy for the isolated system. These conditions can be met by a genset capable of generating approximately 150% of the energy demand. This leads to significantly increased investment costs and deteriorated operational conditions for the genset, resulting in reduced energy conversion efficiency.
Georgescu Sanda-Carmen, Găitănaru Ștefan-Dragoș, Iancu Iulian
et al.
Pumping water from well fields is challenging for any water company, due to the restrictions attached to the aquifers’ hydrogeological characterisation. The difficulty is to set the speed of each pump allowing ensuring a quasi-uniform pumping from all wells in a field, at the highest flow rate that can be extracted from each well, paying attention to avoid clogging. In this paper we propose a methodology to compute the speed of each pump in a well field, corresponding to the desired pumped flow rate range, by keeping the requested hydrodynamic level in each well. The method is exemplified for a case study in Bucharest − a small well field, for which hydrogeological data are available. The nonlinear system of equations that defines the hydraulic system operation is solved in MATLAB for the stationary flow regime attained after reaching constant hydrodynamic levels in all wells. The numerical model of the well field is finally set and run in EPANET, within a dynamic analysis (simulation over an extended period of time), where water levels in the wells adjust to the extracted flow rate, according to the hydrogeological data. Two operating scenarios are discussed.
Asaad M. Armanuos, Martina Zeleňáková, Mohamed Kamel Elshaarawy
Abstract Reliable modeling of saltwater intrusion (SWI) into freshwater aquifers is essential for the sustainable management of coastal groundwater resources and the protection of water quality. This study evaluates the performance of four Bayesian-optimized gradient boosting models in predicting the SWI wedge length ratio (L/L a ) in coastal sloping aquifers with underground barriers. A dataset of 456 samples was generated through numerical simulations using SEAWAT, incorporating key variables such as bed slope, hydraulic gradient, relative density, relative hydraulic conductivity, barrier wall depth ratio, and distance ratio. The dataset was divided into 70% for training and 30% for testing. Model performance was assessed using both visual and quantitative metrics. Among the models, Light Gradient Boosting (LGB) achieved the highest predictive accuracy, with RMSE values of 0.016 and 0.037 for the training and testing sets, respectively, and the highest coefficient of determination (R²). Stochastic Gradient Boosting (SGB) followed closely, while Categorical Gradient Boosting (CGB) and eXtreme Gradient Boosting (XGB) showed slightly higher error rates. SHapley Additive exPlanations (SHAP) analysis identified relative barrier wall distance and bed slope as the most influential features affecting model predictions. To support practical application, an interactive graphical user interface (GUI) was developed, allowing users to input key variables and easily estimate L/L a values. Finally, the best-performing model was validated against the Akrotiri coastal aquifer in Cyprus, a realistic benchmark case derived from numerical simulations. The model’s predictions showed strong agreement with reference results, achieving an RMSE of 0.04, thereby confirming its practical applicability. This study highlights the potential of interpretable, optimized ML models to enhance SWI prediction and support informed decision-making in coastal aquifer management.
Iliya Iliev, Andrey Kryukov, Konstantin Suslov
et al.
The process of establishing relay protection and automation (RPA) settings for electric power systems (EPSs) entails complex calculations of operating modes. Traditionally, these calculations are based on symmetrical components, which require the building of equivalent circuits of various sequences. This approach can lead to errors both when identifying the operating modes and when modeling the RPA devices. Proper modeling of measuring transformers (MTs), symmetrical component filters (SCFs), and circuits connected to them effectively solves this problem, enabling the configuration of relay protection and automation systems. The methods of modeling the EPS in phase coordinates are proposed to simultaneously determine the operating modes of high-voltage networks and secondary circuits connected to the current and voltage transformers. The MT and SCF models are developed to concurrently identify the operating modes of secondary wiring circuits and calculate the power flow in the controlled EPS segments. This method is effective in addressing practical problems related to the configuration of the relay protection and automation systems. It can also be used when establishing cyber–physical power systems. For a comprehensive check of the adequacy of the MT models, 140 modes of the electric power system were determined which corresponded to time-varying traction loads. Based on the results of calculating the complexes of currents and voltages at the MT terminals, parametric identification of the power transmission line was performed. Based on this, the model of this transmission line was adjusted; repeated modeling was carried out, and errors were calculated. The modeling results showed a high accuracy when calculating the modules and phases of voltages using the identified model. The average error value for current modules was 0.6%, and for angles, it was 0.26°.
Precise knowledge of the frequency dependent electromagnetic properties of porous media is urgently necessary for successful utilization of high frequency electromagnetic measurement techniques for near and subsurface sensing. Thus, there is a need of systematic investigations by means of dielectric spectroscopy of unsaturated and saturated soils under controlled hydraulic conditions. In this context, two-port rod based transmission lines (R-TMLs) were characterized in the frequency range from 1 MHz to 10 GHz by combined theoretical, numerical, and experimental investigations. To analyze coupled hydraulic and dielectric soil properties a slightly plastic clay soil was investigated. There is evidence that the bound water contribution of the soil is substantially lower than expected.
The high-pressure transportation process of pipeline necessitates an accurate hydraulic transient simulation tool to prevent slack line flow and over-pressure, which can endanger pipeline operations. However, current numerical solution methods often face difficulties in balancing computational efficiency and accuracy. Additionally, few studies attempt to reform physics-informed learning architecture for pipeline transient simulation with magnitude different in outputs and imbalanced gradient in loss function. To address these challenges, a Knowledge-Inspired Hierarchical Physics-Informed Neural Network is proposed for hydraulic transient simulation of multi-product pipelines. The proposed model integrates governing equations, boundary conditions, and initial conditions into the training process to ensure consistency with physical laws. Furthermore, magnitude conversion of outputs and equivalent conversion of governing equations are implemented to enhance the training performance of the neural network. To further address the imbalanced gradient of multiple loss terms with fixed weights, a hierarchical training strategy is designed. Numerical simulations demonstrate that the proposed model outperforms state-of-the-art models and can still produce accurate simulation results under complex hydraulic transient conditions, with mean absolute percentage errors reduced by 87.8\% and 92.7 \% in pressure prediction. Thus, the proposed model can conduct accurate and effective hydraulic transient analysis, ensuring the safe operation of pipelines.
Laerte Xavier, João Eduardo Montandon, Marco Tulio Valente
Self-Admitted Technical Debt (SATD) is a form of Technical Debt where developers document the debt using source code comments (SATD-C) or issues (SATD-I). However, it is still unclear the circumstances that drive developers to choose one or another. In this paper, we survey authors of both types of debts using a large-scale dataset containing 74K SATD-C and 20K SATD-I instances, extracted from 190 GitHub projects. As a result, we provide 13 guidelines to support developers to decide when to use comments or issues to report Technical Debt.
Los pañales desechables y toallas sanitarias representan una fracción significativa en los residuos sólidos urbanos, generando impactos ambientales sustanciales por su baja biodegradabilidad y lenta descomposición. En Guatemala, existe una escasa caracterización técnica sobre estos residuos, lo que limita su integración en estrategias de gestión. Este estudio se enfoca en el área urbana del municipio de San Miguel Ixtahuacán, departamento de San Marcos, con el objetivo de cuantificar su generación a través de una caracterización específica. Se realizó previamente un censo que identificó 888 viviendas, seleccionando 250 de estas como muestra para el estudio. La producción per cápita de residuos sólidos se estimó en 0.38 kg/hab/día. Los pañales desechables representan 0.13 kg/niño (0–3 años) /día y las toallas sanitarias 0.026 kg/mujer (12–50 años) /día. En promedio, un 17.37% de los residuos totales corresponde a pañales y un 3.53% a toallas sanitarias. Estos valores exceden el promedio nacional para pañales (14%), mientras que las toallas no son consideradas formalmente. La suma indica que más del 20% del residuo generado corresponde a residuos sanitarios, lo que plantea desafíos técnicos y ambientales en cuanto a su manejo, disposición final y posible tratamiento. Se recomienda desarrollar políticas públicas, tecnologías sostenibles y educación ambiental para reducir el impacto ecológico asociado a esta fracción de residuos sólidos urbanos. Este estudio demuestra que estos residuos constituyen un notable problema ambiental.
Engel Alexander Cáceres Sobalvarro, Catalina Paque López
El estudio exploratorio sobre nitritos, nitratos y nitrógeno amoniacal en el drenaje urbano de Ciudad de Guatemala examina la presencia de estos compuestos en los desagües urbanos. Se analiza de forma exploratoria la presencia de estos elementos en las conexiones domiciliares de entes generadores de agua residual de tipo hospitalario y de oficinas, así como en la descarga del drenaje en el cuerpo receptor. El objetivo principal del estudio es determinar qué compuesto tiene mayor presencia en las aguas residuales urbanas. Se caracterizaron 13 puntos de monitoreo, incluyendo cinco conexiones domiciliares, cinco pozos de visita y tres colectores de descargas directas. Los resultados muestran que los nitratos, con un valor medio de 42.714 mg/L, son los más abundantes. Le sigue el nitrógeno amoniacal con un valor medio de 25.856 mg/L, equivalente a 34.82 mg/L de amonio. Las concentraciones medias del nitrato (42.714 mg/L) es un 65.2% mayor que la concentración media de nitrógeno amoniacal (25.856 mg/L) Las conclusiones indican que los sistemas de drenaje favorecen la nitrificación, transformando el nitrógeno amoniacal en nitratos. Este estudio destaca la importancia de comprender la dinámica de estos compuestos en los drenajes. Entender dicha dinámica permitirá abordar mejor los impactos en el medio ambiente, la salud pública y el tratamiento de aguas residuales.
Iliya K. Iliev, Andrey V. Kryukov, Konstantin V. Suslov
et al.
This paper presents the findings of the research aimed at developing computer models to determine the operating conditions in electric power systems (EPSs) feeding DC and AC railway substations. The object of the research is an EPS with a predominant traction load whose high-voltage power lines are connected to transformer and converter substations with 3 kV and 27.5 kV traction networks. The supply network includes 110 kV and 220 kV power lines. The EPS operating parameters are calculated based on the decomposition of the system into alternating and direct current segments. Calculations are performed for the fundamental frequency and high harmonic frequencies. The modeling technique is universal and can be used to determine the operating parameters and power quality indices for any configuration of an EPS and various designs of traction networks. With this technique, one can solve numerous additional problems, such as calculating the processes of ice melting in traction networks and power lines, determining electromagnetic field strengths, and assessing the heating of power line wires and catenary suspensions. The results obtained show that the voltages on the current collectors are within acceptable limits for all AC and DC electric locomotives. The levels of asymmetry on the 110 and 220 kV tires of traction substations (TP) do not exceed the normally permissible values. The values of the asymmetry coefficients for DC TP are tenths of a percent. With an increase in the size of traffic and in post-emergency conditions caused by the disconnection of communication between one of the support substations and the EPS, the asymmetry indicators on the 220 kV buses of AC substations may exceed the permissible limits. Phase-controlled reactive power sources can be used to reduce them. The analysis of the results of the determination of non-sinusoidal modes allows us to formulate the conclusion that the values of harmonic distortion go beyond the normative limits. Passive and active filters of higher harmonics can be used to normalize them. Calculations of thermal modes of traction transformers show that the temperatures of the most heated points do not exceed acceptable values.
Though a number of formulations have been proposed for phase--field models for hydraulic fracture, the definition of the degraded poroelastic strain energy varies from one model to another. This study explores previously proposed forms of the poroelastic strain energy with diffused fracture and assesses their ability to recover the explicit fracture opening aperture. We then propose a new form of degraded poroelastic strain energy derived from micromechanical analyses. Unlike the previously proposed models, our poroelastic strain energy degradation depends not only on the phase--field variable (damage) but also on the type of strain energy decomposition. Comparisons against closed form solutions suggest that our proposed model can recover crack opening displacement more accurately irrespective of Biot's coefficient or the pore--pressure distribution. We then verify our model against the plane strain hydraulic fracture propagation, known as the KGD fracture, in the toughness dominated regime. Finally, we demonstrate the model's ability to handle complex hydraulic fracture interactions with a pre--existing natural fracture.
Geosynthetics are well known for substituting mineral filter layers for revetments. Apart from this established and common application they offer more specific and technical solutions for coastal and inland water structures. Typical hydraulic constructions like breakwaters and dikes can be strengthened and optimised using geotextiles or geosystems (bags, tubes, etc.). Till today the potential of geosynthetics for civil works in the marine environment is underestimated. Furthermore, the awareness by designers, construction companies and project owners for geotextile alternatives, saving time, money and enhancing the carbon footprint, can be substantially increased. Main reasons for the ignorance are missing design guidelines and a not existing general overview of their applicability in coastal zones and inland waters. This paper is intended as a first step towards a holistic approach to geosynthetics in hydraulics.
Abstract Unlike actual rainfall, the spatial extent of rainfall maps is often determined by administrative and political boundaries. Similarly, data from commercial microwave links (CMLs) is usually acquired on a national basis and exchange among countries is limited. Up to now, this has prohibited the generation of transboundary CML‐based rainfall maps despite the great extension of networks across the world. We present CML based transboundary rainfall maps for the first time, using independent CML data sets from Germany and the Czech Republic. We show that straightforward algorithms used for quality control strongly reduce anomalies in the results. We find that, after quality control, CML‐based rainfall maps can be generated via joint and consistent processing, and that these maps allow to seamlessly visualize rainfall events traversing the German‐Czech border. This demonstrates that quality control represents a crucial step for large‐scale (e.g., continental) CML‐based rainfall estimation.
Doris Hermle, Markus Keuschnig, Michael Krautblatter
et al.
Accurate and reliable analyses of high-alpine landslide displacement magnitudes and rates are key requirements for current and future alpine early warnings. It has been proved that high spatiotemporal-resolution remote sensing data combined with digital image correlation (DIC) algorithms can accurately monitor ground displacements. DIC algorithms still rely on significant amounts of expert input; there is neither a general mathematical description of type and spatiotemporal resolution of input data nor DIC parameters required for successful landslide detection, accurate characterisation of displacement magnitude and rate, and overall error estimation. This work provides generic formulas estimating appropriate DIC input parameters, drastically reducing the time required for manual input parameter optimisation. We employed the open-source code DIC-FFT using optical remote sensing data acquired between 2014 and 2020 for two landslides in Switzerland to qualitatively and quantitatively show which spatial resolution is required to recognise slope displacements, from satellite images to aerial orthophotos, and how the spatial resolution affects the accuracy of the calculated displacement magnitude and rate. We verified our results by manually tracing geomorphic markers in orthophotos. Here, we show a first generic approach for designing and optimising future remote sensing-based landslide monitoring campaigns to support time-critical applications like early warning systems.
The Calcasieu Ship Channel (CSC) is a deep-draft federal channel located in southwest Louisiana. It is the channelized lowermost segment of the Calcasieu River, connecting Lake Charles to the Gulf of Mexico. With support from the Regional Sediment Management Program, the US Army Corps of Engineers, New Orleans District, requested that the US Army Engineer Research and Development Center, Coastal and Hydraulics Laboratory, perform an investigation of the potential sources of sediment associated with dredging in the CSC. A previous study had quantified sediment from known sources, indicating that the known sediment sources contribute approximately only 21% of the volume that is regularly dredged from the channel. This technical report details the results of the current study, which employed multiple methods, including numerical analysis, to identify potential additional sources of sediment by first examining the available literature and the modeled energetics and flow pathways, and then estimating the quantities of sediment associated with these identified sources that may be contributing to the shoaling of the CSC. The results of these efforts were used to update the original sediment budget with estimates of the contributions from two additional sources: the erosion of interior wetlands and coastally derived sediments.