Recent publications
The paper deals with monitoring the quality of a shaped part of a mould made from H13 tool steel using additive manufacturing. The shaped part of the mould is a key element in the casting of aluminium alloys by high pressure die casting (HPDC) technology and has a major influence on achieving the desired quality of the casting. This paper presents an evaluation methodology which includes the results of surface quality analysis and dimensional accuracy and stability of additively manufactured parts. These analyses were carried out from the production of the mould part to its application in the foundry operating conditions. The comprehensive analyses offer an overall view of the changes caused by individual technological operations. These operations are additive manufacturing, heat treatment, machining, and final coating before implementation into the operating conditions of the foundry. The paper also describes monitoring the quality of the mould part in regular cycles during the production of aluminium castings. This methodology and the results provide new insights in the field of engineering metallurgy.
Differently substituted pyrrole‐azo–benzene molecular photoswitches were prepared in a straightforward synthetic way. Their fundamental properties were investigated by XRD analysis, differential scanning calorimetry, thermogravimetric analysis, cyclic voltammetry, UV–Vis absorption spectroscopy, Hyper‐Rayleigh Scattering, and NMR spectroscopy; the experimental results were further corroborated by DFT calculations. Thermal robustness, the HOMO/LUMO levels, and the absorption properties were altered mostly by substituting the N–methylpyrrole moiety and further fine‐tuned by modifying the benzene substituents. The pyrrole substituent also proved crucial for the second‐order non–linear optical (NLO) response as well as the photoswitching performance. Both fast and slow molecular switches can be designed with the half–life of the (Z) –isomer ranging from 48 seconds to 23.28 hours and the E/Z molar ratio up to 12/88. This comprehensive study allowed elucidation of the fundamental structure‐property relationships and subsequently addresses the key aspects of the property tuning via substitution in molecular azo‐photoswitches.
The paper describes the design of conformal cooling of an aluminium die-casting mold component using numerical simulations along with validation under industrial conditions. The subject of modifications was the insert. The insert comes into direct contact with the metal during the filling of the mold and solidification of the casting and determines the internal shape of the casting. The aim was to optimize the operating temperatures of the insert, reduce thermal stress in the most exposed area, achieve a more even distribution of temperatures in its volume, and maintain the casting quality. Shape modifications were made by topology optimization to reduce the volume of the insert and achieve material savings. 3D printing was chosen as the production technology due to the wider possibilities regarding the variability of the shape of the internal cooling channels. Three geometric designs of the insert were created, and numerical simulations of the temperature field of the mold were carried out in ProCAST software for each variant. Numerical simulations were validated through the temperature field of the mold detected by a thermal camera during the casting cycle. Based on the results, the final design D was selected, for which a complete numerical simulation was performed, including the filling and solidification of the castings. The results were compared with the original variant A. By adjusting the cooling, temperatures were reduced in the most temperature-exposed area of the insert. The new insert variant D showed higher temperatures in the rest of the volume, resulting from material volume reduction. However, the temperatures became even, and the temperature gradients that existed in the original insert variant A were reduced. The simulation also showed that changes in the temperature field of variant D will not negatively affect the quality of the castings. The component will be manufactured and tested in operational conditions in the next research phase.
The article aims to explore and tackle safety issues, including emergency evacuation schemes in the DURA Automotive CZ LP, using the Pathfinder simulation program by Thunderhead Company. We ran twelve simulations, where six tested the existing conditions and six evaluated the implemented remedial measures. The simulation input data involved two parameters, including full occupancy, morning and afternoon (night) shifts. The first simulation profile observes ČSN 73 0804 [4], while the second implementation complied with Kady, Rani A and Davis, Peacock et al. [9] profiles. Each survey determines different average speeds on a flat surface and staircase to identify and remove impediments in the evacuation scheme, including a critical number of people on the first floor and using the only emergency exit within the fire escape. The suggested remedial measures must observe the necessary evacuation time before and after introducing the preventive action, the essential parameter for evaluating the effectiveness of evacuation procedures.
The global electric vehicle (EV) market is dominated by three global powers: China, the USA, and the European Union. Each of these three regions has adopted unique strategies and differs in terms of regulations, government policies, and market structure. The growth of the EV market in these countries is driven by both climate policies and economic and technological ambitions. Discussing these three markets illustrates the directions of development for the global EV market, as well as its future challenges and potential. This article provides a detailed characterization of the policies pursued by these three economies based on a literature review and its synthesis. It then conducts a quantitative analysis of the electric vehicle markets using a trend development study and calculates the sales elasticity index. The future of the global electric vehicle market will largely be shaped by the development of policies, infrastructure, and innovations in these three regions, each of which has a unique approach to EV development. On one hand, these differences may lead to increased competition among the three powers in the coming decades, fostering further innovation and the development of technologies that support the sustainable growth of the EV market. On the other hand, the analysis of strategies implemented thus far may serve as an excellent benchmark for other countries.
This paper examines whether and how non-state-owned enterprise (non-SOE) business groups affect a firm’s green innovation. On the basis of a sample of A-share listed companies on the Shanghai and Shenzhen stock exchanges from 2007 to 2021 and hand-collected business group data, we document a negative association between non-SOE business groups and corporate green innovation. Furthermore, we identify two different mechanisms that may explain this relationship from various perspectives: firms’ motivation for benefit maximization and the ability to lighten government environmental regulations. We also find that this negative correlation is more pronounced in competitive industries and is related to reduced executives' environmental awareness, reduced intensity of environmental regulation, and greater official pressure to promote. Our findings not only help improve the existing literature on business groups and corporate green innovation but also provide empirical evidence that non-SOE business groups can negatively affect corporate green innovation.
This study investigates the effect of macroeconomic and bank-specific factors on the bank interest rate spread (IRS) of six Western Balkan countries (referred to as WB6). We applied the Panel Vector Autoregression (Panel VAR) model to separately analyze the impact of these two sets of factors for 2005 to 2022 using two-panel datasets from 110 banks. The results from the two models show that the IRS is significantly influenced by GDP per capita and the unemployment rate, while other factors, such as bank concentration, performance indicators, and non-performing loans, show limited direct effects. The study identifies a notable gap in the existing literature by emphasizing how macroeconomic and bank-specific variables, particularly in transition economies, can simultaneously affect the IRS. The research highlights the distinctive financial dynamics within the WB6 countries and the relevance of comprehending the region’s banking sector characteristics. It contributes to academic and policy discussions on the significance of financial stability and market competitiveness in determining the bank IRS. The findings can be helpful for banking regulators and policymakers in the Western Balkans seeking to foster an efficient and competitive banking environment.
JEL Classification: C33, E43, G21.
The presented publication deals with the method of optimisation of dimensions of specific bearing rings on the basis of the production process of grinding the surfaces of the faces and outer surfaces of these bearings after turning and hardening by means of a suitable addition corrected by a suitable number of grinding passes. By comparing the analysed results of bearing ring dimensions measurements obtained after turning and hardening before and after optimisation, the capability indices of the applied manufacturing processes are evaluated. In the context of standard values of capability indices common in engineering practice, the proposed method aims at achieving higher product quality, as well as increasing the efficiency and economic benefit of the applied manufacturing processes.
Every year, there is a decline in the number of car accidents reported in Poland, the Czech Republic, and globally. While recent trends due to the pandemic have influenced these figures, the overall rate remains significant. Therefore, it is crucial to take measures aimed at reducing this number. The primary focus of this article is to analyze the traffic accident statistics for Poland and the Czech Republic. Annual data regarding traffic incidents in both countries has been scrutinized to achieve this. Projections for 2024 to 2030 have been developed based on police reports. Various neural network models were utilized to forecast the number of accidents. The findings indicate that the number of traffic incidents is likely to stabilize. This stabilization can be viewed in the context of the increasing number of vehicles on the roads and the expansion of new highways. Additionally, selecting sample sizes for training, testing, and validation is crucial in influencing the results. Forecasting the number of traffic accidents is important for environmental protection, as accidents can lead to air and water pollution and increase noise, negatively affecting human health and ecosystems.
The article presents the results of research carried out using a water model of a refining ladle for the Fe–Si ferroalloys treatment. These studies were aimed at improving the efficiency of refining and homogenization of liquid Fe–Si ferroalloy in the refining ladle by using a new method of blowing gas through a system of nozzles installed at the bottom of the ladle. The obtained results allowed to determine the proper location of the plug at the bottom of the refining ladle and the possibility of using combined blowing. The tests were carried out for a refining ladle with a capacity of 3 m³ using a physical model on a linear scale of 1:3. The gas flow rate used in the model corresponded proportionally to the value previously used in industrial practice and amounted to 26.8 l/min. Experiments were performed for both combined blowing applications and through a purging plug at the bottom of the ladle. In the case of combined blowing, the volume of the gas stream was divided into two blowing sources (lance and purging plug). As a result of laboratory tests, one of the variants was selected and tested in industrial conditions. These studies confirmed the improvement in the efficiency of refining treatment of the FeSi alloy in terms of reducing the carbon and aluminum content in the alloy.x
Road traffic constitutes a key element of modern life, with many individuals behind the wheel each day. Their driving style, specifically how they accelerate and brake, can significantly influence emissions of harmful substances and air quality. Despite the presence of modern cars equipped to reduce exhaust gas components and other emissions, driving style continues to have a substantial impact on air pollution. In the case of aggressive driving, the influence on fuel consumption and emission generation is substantial. Another aspect is the safety of road traffic, as it has been proven that aggressive driving reduces safety. This article focuses on the results of our recent research regarding vehicle emissions during acceleration. We found that even though modern cars are increasingly environmentally friendly, aggressive driving with them can quickly change the perspective on this issue. While the acceleration of a single vehicle may seem essentially negligible, it is crucial to realize that, especially in urban environments, the number of accelerations of road vehicles as a traffic flow is enormous, particularly during peak traffic hours. Furthermore, there are locations where vehicles must decelerate and accelerate consistently, such as certain types of intersections. The goal of the article is to provide an additional viewpoint on monitoring this trend, this time in combination with the road infrastructure itself, with three examples discussed in the article on how these negative trends can be influenced through modifications to the road infrastructure.
The relation between Riemannian geodesic graphs and Finslerian geodesic graphs proved in a previous work is illustrated with explicit constructions. Interesting examples are found such that is Riemannian geodesic orbit space, but for the geodesic orbit property of (G/H, F) the isometry group has to be extended. Consequently, an alternative approach to the classification of invariant geodesic orbit Finsler metrics F which arise from Riemannian geodesic orbit metrics on spheres is obtained. It is also shown that projective spaces other than do not admit invariant purely Finsler metrics.
With the concept of Industry 4.0 production processes are moving towards autonomy and intelligence. Technologies equipped with artificial intelligence (AI) are involved into processes that are more and more digitized. Collaborative technologies are a feature of discrete processes. The automotive industry has achieved many successes in the process innovation towards smart factories. Other plants, such as smelters or coal mining are also striving to develop smart manufacturing with integrated computer systems to support processes. A continuous production is different from a discrete or batch production. Industry 4.0 concept is focused on discrete production (with high level of automation and robotization of manufacturing) meanwhile there is a gap in implementation of these approach in the continuous production. The objective of the publication is to prepare and design the integrated computer management system based on processes realized in coal and steel manufacturing. Coal and steel production are key elements in a chain of any industrial manufacturing e.g. automotive or machinery engineering. These processes are crucial in building of smart value chain. In our paper we present the structure of processes for the continuous production. Based the processes model we proposed the next steps to build the smart manufacturing for continuous production.
This article discusses fundamental issues associated with the functional reliability of selected fire alarm systems (FASs) in operation during building fires. FASs operate under diverse external or internal natural environmental conditions, and the operational process of FAS should take into account the impacts of physical phenomena that occur during fires. Their operation is associated with the constant provision of reliability. FAS designers should also consider the system’s reliability when developing fire control matrices, tables, algorithms, or scenarios. All functions arising from an FAS control matrix should be implemented with a permissible reliability level, RDPN(t), prior to, as well as during, a fire. This should be assigned to the controls saved in the fire alarm control unit (FCP). This article presents the process by which high temperatures generated during a fire impact the reliability of FAS functioning. It was developed considering selected critical paths for a specific scenario and the control matrix for an FAS. Such assumptions make it possible to determine the impact of various temperatures generated during a fire on the reliability of an FAS. To this end, the authors reviewed that the waveform of the R(t) function changes for a given FAS over time, Δt, and then determined the fitness paths. The critical paths are located within the fire detection and suppression activation process, using FAS or fixed extinguishing devices (FEDs), and the paths were modeled with acceptable and unacceptable technical states. The last section of this article defines a model and graph for the operational process of a selected FAS, the a
Currently, there are many mathematical models and tools for inventory management and optimization. Based on the literature review, the authors conclude that inventory management tools and models are mostly one-sided and focused on the cost aspect of the inventory management process. The research goal was to propose a set of criteria for inventory optimization as a basis for the development of an inventory management model whose structure would consider both the economic aspect and the stochasticity of demand and the reliability of delivery. Optimization criteria are based on extensive analyses of influences and correlations between logistic chain subsystems in relation to inventory. The interactions of the subsystems are then mathematically expressed, which represents the main output of the created set of optimization criteria. The defined criteria can be used as a basis for creating a new optimization model of inventory management.
The aim of the study is to identify the importance of partial communication factors of sustainable products for the Czech consumer. First, the data from an online survey is interpreted in the form of descriptive statistics to establish a comprehensive overview of the attitudes and preferences of Czech consumers. Second, the global envelope method is used to evaluate reactions to packaging, certificates, ingredients, in-store placement, awareness, sales in a sustainable store, higher prices, and other factors among selected target groups. Based on the results of the 2020 questionnaire survey, significant target groups were identified by frequency analysis and their responses to communication factors were monitored for apparel, drugstore and cosmetics, and food. The test results show that clearly the most important communication factor for sustainable products is the certificate, to a large extent for two categories: males 45 – 64 years old and females who are university educated.
Regulation of gene expression is arguably the main mechanism underlying the phenotypic diversity of tissues within and between species. Here we assembled an extensive transcriptomic dataset covering 8 tissues across 20 bilaterian species and performed analyses using a symmetric phylogeny that allowed the combined and parallel investigation of gene expression evolution between vertebrates and insects. We specifically focused on widely conserved ancestral genes, identifying strong cores of pan-bilaterian tissue-specific genes and even larger groups that diverged to define vertebrate and insect tissues. Systematic inferences of tissue-specificity gains and losses show that nearly half of all ancestral genes have been recruited into tissue-specific transcriptomes. This occurred during both ancient and, especially, recent bilaterian evolution, with several gains being associated with the emergence of unique phenotypes (for example, novel cell types). Such pervasive evolution of tissue specificity was linked to gene duplication coupled with expression specialization of one of the copies, revealing an unappreciated prolonged effect of whole-genome duplications on recent vertebrate evolution.
Plastics represent an integral part of our everyday lives, with various functions from packaging materials to insulation layers in our buildings. Pure expanded polystyrene (EPS) is a good example of a fully recyclable material. However, once polluted with other materials or substances, EPS becomes a serious environmental burden. In this work, waste EPS for the production of greener building composites with balanced properties and utility value was investigated. Natural aggregate (2/4 mm) was substituted with corresponding fractions of a thermoplastic alternative in portions of 25, 50, 75, and 100 vol.%. The comprehensive experimental investigation evaluated physical and mechanical properties, heat transport and accumulation, and water absorption characteristics. Due to the uniformly distributed plastic particles in the hardened cement-based matrix, the data revealed an important reduction in the dead weight of produced mortars, which also reduced thermal conductivity by up to 47%. On one hand, lightweight mortars showed partially reduced mechanical resistivity; on the other hand, the EPS bead-modified structure turned out to be effective in liquid water transport reduction.
With the introduction of the concept of the industry 4.0, automation, robotics, artificial intelligence, communication methods, automotive engineering, mechanics, construction and operation of automotive vehicles, and so on, as well as the methods of corporate management are changing. Following this concept, new risks emerge, when workers have to cooperate with collaborative robots, autonomous systems, artificial intelligence, machine learning and learn new methods different from previous processes and systems. The paper first presents the theoretical background related to the topic addressed. The next sections encompass the literature review, including a list of references relevant to achieving the main objective of the paper, as well as a description of the research methods used in the paper. With regard to the main objective, quantitative research concerning the vehicle construction systems' safety issues in industry 4.0 was conducted; i.e., a questionnaire survey was developed within a sufficiently representative sample of respondents. After conducting the survey, the risk assessment model of vehicle construction systems' safety under the conditions of Industry 4.0 was proposed while applying the principles of system dynamics. An integral part of the paper is represented by the discussion of the obtained results and benefits, as well as the formulation of relevant conclusions.
Institution pages aggregate content on ResearchGate related to an institution. The members listed on this page have self-identified as being affiliated with this institution. Publications listed on this page were identified by our algorithms as relating to this institution. This page was not created or approved by the institution. If you represent an institution and have questions about these pages or wish to report inaccurate content, you can contact us here.
Information
Address
České Budějovice, Czechia
Website