A preconditioned conjugate gradient domain decomposition method was given Refs 1 and 2 for the solution of a system of linear equations arising in the finite element method applied to the elliptic Dirichlet, Neumann and mixed boundary value problems. We have proved that the construction can be generalized² for higher order finite element method. Here we give a construction and theoretical investigation of preconditioners for second order finite elements. A method and the the results of calculation is given. The presented numerical experiments show that this preconditioner works well. © 1995.

The Traveling Salesman Problem (TSP) is an NP-hard graph search problem. Despite having numerous modifications of the original abstract problem, Time Dependent Traveling Salesman Problem (TD TSP) was one of the most realistic extensions under real traffic conditions. In TD TSP the edges between nodes are assigned higher costs (weights), if they were traveled during the rush hour periods, or crossed the traffic jam regions, such as the city center(s). In this paper we introduce an even more real-life motivated approach, the Intuitionistic Fuzzy Time Dependent Traveling Salesman Problem (IFTD TSP), which is a further extension of the TSP, and also of the classic TD TSP, with the additional notion of using intuitionistic fuzzy sets for the definition of uncertain costs, time, and space of the rush hour—traffic jam region affecting graph sections. In IFTD TSP we use fuzzy memberships and non-memberships sets for estimating the vague costs between nodes in order to quantify the behavior of traffic jam regions, and the rush hour periods. Since intuitionistic fuzzy sets are generalizations of classic fuzzy sets, our approach may be considered an extension and substitution of the original abstract TD TSP problem, even, of the (classic) Fuzzy TD TSP. Lastly, DBMEA (Discrete Bacterial Memetic Evolutionary Algorithm) was applied on the IFTD TSP model, the results of the simulation runs based on some extensions of the benchmarks generated from the original TD TSP data set showed quite good and promising preliminary results.

In fuzzy cognitive maps (FCMs) based modelling paradigm, the complex system's behaviour is gathered by the causal connections acting between its main characteristics or subsystems. The system is represented by a weighted, directed digraph, where the nodes represent specific subsystems or features, while the weighted and directed edges express the direction and strength of causal relations between them. The state of the complex system represented by the so-called activation values of the nodes, that is computed by an iterative method. The FCM based decision-making relies on the assumption that this iteration reaches an equilibrium point (fixed point), but other types of behaviour, namely limit cycles and chaotic patterns may also show up. In practice, the weights of connections are estimated by human experts or machine learning methods. Both cases have their own uncertainty, which can be represented by using intervals as weights instead of crisp numbers. In this paper, sufficient conditions are provided for the existence and uniqueness of fixed points of fuzzy cognitive maps that are equipped with interval weights, which also ensure the global asymptotic stability of the system.

One of the causes of centrifugal pump instability lies in the phenomenon of cavitation. Cavitation in the centrifugal pump can produce undesirable effects such as deterioration in hydraulic performance. In order to prevent the emergence of cavitation, it is required to know the onset point of the cavitation, in the pump. Our study presents the process and result of the cavitation measurement performed on a centrifugal pump in a closed loop test system. In this study, we applied CFD analysis, which serves as a means of measuring flow in the impeller of the centrifugal pump. The results gained from CFD analysis correspond, approximately, to the measured results.

The e-commerce sector has experienced significant growth in the past two decades, outpacing other economic sectors and contributing to sustainable consumption, increased labour productivity, competitiveness, consumer incomes, and GDP growth. This trend is expected to continue, making e-commerce a key driver of sustainable economic growth in Europe. This study aims to explore the relationship between a nation’s innovation level and its population’s inclination towards online shopping in various EU member states. It hypothesizes that higher innovation levels within a country lead to a greater tendency for online purchases. This study conducts a thorough analysis of the interplay between European economies’ innovation levels and the e-commerce market’s evolution. A composite innovation index was created using the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) methodology, and panel data models were utilized to examine the dependencies, with data from Eurostat and the Global Innovation Index. The focus is on the period from 2019 to 2021, which was marked by unique market dynamics and the impact of the COVID-19 pandemic. The findings confirm the significant role of innovation in driving e-commerce expansion within the context of sustainable consumption, supporting the main hypothesis. This research also highlights the pandemic’s positive effect on the e-commerce sector. The pandemic-induced changes in consumer behaviour, particularly due to social isolation and crises in certain economic sectors, have emphasized the importance of online shopping. Notably, the most active online shoppers are identified in the 25 to 54 age group, revealing a key demographic trend.

Hypselostomatidae is a large family of terrestrial pulmonate molluscs currently represented by 284 extant species, most confined to Southeast Asia. The current system of grouping species into genera is based on the morphology of the apertural barriers and the level of last whorl detachment. However, these characters overlap, challenging generic definitions. In this paper, these characters are evaluated and a novel classification proposed for hypselostomatid species belonging to the genera Anauchen (17 species), Bensonella (36 species), Boysidia (7 species, in part) and Hypselostoma (85 species). We assigned all species belonging to the genera Bensonella and Hypselostoma into two and four species groups respectively, which are characterised by combinations of morphological traits. Altogether 46 new species are described, seven species in Anauchen: A. crassus Gojšina, Hunyadi & Páll-Gergely, sp. nov., A. evanidus Gojšina & Páll-Gergely, sp. nov., A. grandiportus Gojšina, Grego & Páll-Gergely, sp. nov., A. obesus Gojšina, Hunyadi & Páll-Gergely, sp. nov., A. picasso Gojšina & Páll-Gergely, sp. nov., A. turritus Gojšina, Hunyadi & Páll-Gergely, sp. nov., A. jokaii Gojšina & Páll-Gergely, sp. nov.; 19 species in Bensonella: B. alycaeus Gojšina & Páll-Gergely, sp. nov., B. cardiostoma Gojšina, Vermeulen & Páll-Gergely, sp. nov., B. cristatissima Gojšina, Hunyadi & Páll-Gergely, sp. nov., B. dha Gojšina, Hunyadi & Páll-Gergely, sp. nov., B. dracula Gojšina, Hunyadi & Páll-Gergely, sp. nov., B. exploda Gojšina, Hunyadi & Páll-Gergely, sp. nov., B. fracta Gojšina, Hunyadi & Páll-Gergely, sp. nov., B. microdentata Gojšina & Páll-Gergely, sp. nov., B. mitochondria Gojšina, Vermeulen & Páll-Gergely, sp. nov., B. mirabilis Gojšina, Hunyadi & Páll-Gergely, sp. nov., B. montawa Gojšina, Hunyadi & Páll-Gergely, sp. nov., B. multidentata Gojšina, A. Reischütz & Páll-Gergely, sp. nov., B. nitens Gojšina & Páll-Gergely, sp. nov., B. obex Gojšina, Hunyadi & Páll-Gergely, sp. nov., B. perfecta Gojšina & Páll-Gergely, sp. nov., B. sericata Gojšina & Páll-Gergely, sp. nov., B. serrata Gojšina, Hunyadi & Páll-Gergely, sp. nov., B. spelaea Gojšina, Grego & Páll-Gergely, sp. nov., B. spinosa Gojšina, Hunyadi & Páll-Gergely, sp. nov.; 20 species in Hypselostoma: H. aquila Gojšina, Hunyadi & Páll-Gergely, sp. nov., H. bubalus Gojšina, Hunyadi & Páll-Gergely, sp. nov., H. circumcarinatum Gojšina, Auffenberg & Páll-Gergely, sp. nov., H. coriaceum Gojšina & Páll-Gergely, sp. nov., H. aenigma Gojšina, Grego & Páll-Gergely, sp. nov., H. fortunatum Gojšina, Hunyadi & Páll-Gergely, sp. nov., H. fungus Gojšina, Hunyadi & Páll-Gergely, sp. nov., H. geckophilum Gojšina, Hunyadi & Páll-Gergely, sp. nov., H. iunior Gojšina & Páll-Gergely, sp. nov., H. ophis Gojšina, Hunyadi & Páll-Gergely, sp. nov., H. platybasis Gojšina, Hunyadi & Páll-Gergely, sp. nov., H. populare Gojšina, Hunyadi & Páll-Gergely, sp. nov., H. sculpturatum Gojšina, Hunyadi & Páll-Gergely, sp. nov., H. similare Gojšina, Hunyadi & Páll-Gergely, sp. nov., H. sorormajor Gojšina, Hunyadi & Páll-Gergely, sp. nov., H. sororminor Gojšina, Hunyadi & Páll-Gergely, sp. nov., H. torta Gojšina, Auffenberg & Páll-Gergely, sp. nov., H. vesovici Gojšina & Páll-Gergely, sp. nov., H. vicinum Gojšina, Auffenberg & Páll-Gergely, sp. nov., H. vujici Gojšina & Páll-Gergely, sp. nov. One replacement name is proposed: H. tertiusfrater Gojšina & Páll-Gergely, nom. nov. pro Boysidia salpinx F. G. Thompson & Dance, 1983, non Hypselostoma salpinx (van Benthem Jutting, 1961) (originally described as Gyliotrachela). Gyliotrachela and Antroapiculus are both treated as junior synonyms of Hypselostoma. An additional 28 species and subspecies are reassigned to the synonymies of other taxa.

The functioning of energy markets is essential for global stability and is heavily influenced by geopolitical risks. Understanding these risks is critical for policymakers, market analysts, and nations. This study investigates the impact of geopolitical risks and their components on the futures markets of WTI crude oil and natural gas, utilizing time and frequency connectedness analysis along with impulse response function methods. The analysis is based on a dataset comprising daily prices of spot and futures contracts (across various maturities) as well as treasury yields. Our findings reveal that geopolitical risks have a significant, negative impact on the interest-adjusted spread of WTI crude oil. In contrast, the interest-adjusted spread of natural gas futures (NGF) displays a more complex pattern: while short-term maturities show an insignificant response, long-term maturities exhibit a significant reaction. Spillover effects are more pronounced in the short term but tend to weaken over longer horizons. This study underscores the dynamic influence of geopolitical risks on both key energy markets. Its findings offer a practical framework for risk management, equipping market participants and policymakers with valuable insights to better understand and respond to geopolitical risks in the energy sector.

It is common in the practice of bridge design to analyze the superstructure, substructure, and foundation components separately. Applying this kind of modeling, soil-structure interaction effects can only be approximated with moderate accuracy. The foundation stiffness can greatly influence the internal forces, stresses, and displacements of superstructure. This is especially true for portal frame and integral bridges. Better modeling of soil-structure interaction can use three-dimensional geotechnical FEM programs, where the true soil-stucture environment can be analyzed. It is possible to use nonlinear constitutive models; capable of modeling soil behavior accurately, however it is difficult, time consuming, and costly in day-to-day practice.

Process flowsheet synthesis, design, and simulation require integrated approaches that combine domain knowledge and data-driven methods for fast, efficient, and reliable solutions. However, due to the recent surge in data and machine learning capabilities, there has been a shift towards building purely data-driven systems for process flowsheet synthesis and related problems. Such approaches have certain drawbacks. Here, we present a hybrid method that combines data-driven approaches with domain knowledge to represent process flowsheets and solve problems related to process synthesis, design, and simulation. We present an extended SFILES (or eSFILES) representation, a multi-level hierarchical flowsheet representation with varying degrees of process knowledge. At level 0, flow diagrams are represented as purely text-based SFILES strings. At level 1, the SFILES grammar, along with inferencing algorithms, is used to construct a flowsheet hypergraph explicitly representing flow diagram connectivity. At level 2, specifications needed for material and energy balance calculations are introduced, and, after simulation, the results are also added using annotated flowsheet hypergraphs. Finally, at level 3, a process ontology is connected with the annotated flowsheet hypergraph to include design and operation parameters as well as the detailed simulation results. We discuss this hierarchical framework using several case studies.