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An innovative iterative approach to solving Volterra integral equations of second kind
Get PDFMany scientists have shown great interest in exploring the realm of second-kind integral equations, offering many techniques for solving them, including exact, approximate, and numerical methods. This paper introduces the Hussein-Jassim method (HJ-method) for solving Volterra integral equations of the second kind (VIESKs). The foundation of this approach lies in the principle of Maclaurin expansion. The algorithm of the method was derived, and its convergence was analysed. Furthermore, the method was applied to various Volterra integral equations, encompassing linear, nonlinear, homogeneous, and nonhomogeneous cases. Ultimately, the proposed method successfully addressed these equations, with the approximate solutions converging toward the exact solution
Precipitation of oxide dispersion strength steels after long-term annealing at temperature of 475 °C
Get PDFOxide dispersion strengthened steels are key alloys used in nuclear installations. Steels with chromium content of up to 10 wt % are suitable due to their advantageous properties and these alloys are used for the construction of technological devices in the primary circuit of nuclear power plants. From other studies, it can be concluded that chromium has anti-corrosive properties due to the formation of a passivation layer, which results in reduced activation of the material by thermal neutrons. Macroscopic properties are determined by their microstructure, and therefore, the description of the microstructure is important. Transmission Mössbauer spectroscopy and atom probe tomography were used to characterise the material. This provides information about the physical and/or chemical environment of the resonant atoms can be obtained. Obtained spectral parameters reach saturation values from which the solubility limit of chromium in iron can be determined. In Cr-rich phase, the solubility limit can be estimated from the value of spectral parameters of the single-line in the spectrum annealed for the longest time. The suggested procedures are subsequently applied to the case studies of stainless steels suitable for the construction of various components of the III+/IVth generation of nuclear reactors (including fast and fusion reactors)
Prague postal time service: clock and sirens – improbable connection
Get PDFThe goal of this paper is to present the origin, development, and technical parameters of the Postal Time Service, which was established in the capital of Czechoslovakia – Prague, gradually in the years 1933–1935. It also examines the options for determining “public time” in the period before the establishment of this service. In the second part, the text deals with the question of the use of the Postal Time Service infrastructure as an essential part of the air raid alarm siren system. The emergence of this system will be set in the broader context of the deteriorating security and political situation in Central Europe in the second half of the 1930s. In addition to the technical aspects of the warning system itself, the text will also introduce its author, Prof. František Rieger of the College of Mechanical and Electrical Engineering of the Czech Technical University in Prague, and the practical tests of the device, which took place in 1936 and 1937
Damage detection on cooling tower shell based on model textures
Get PDFEnsuring the structural integrity of cooling towers is paramount for safety and efficient operation. This paper presents a novel approach for detecting damage on cooling tower shells, utilising textures derived from laser scanning and close-range photogrammetry. The proposed method delves beyond the limitations of solely relying on colour information by harnessing the rich details embedded in various textures, including diffuse, normal, displacement, and occlusion. The study demonstrates the efficacy of this approach for identifying significant concrete damage. A Convolutional Neural Network (CNN) trained on diffuse textures successfully detects high damage instances with minimal misdetection. However, accurately pinpointing low damage, often manifesting as subtle cracks, and mimicking other patterns like air pores, ribbing, and colour variations, presents a formidable challenge. To tackle this challenge, the authors introduce a novel "composed raster layer" that merges information from multiple textures. This pre-processed layer amplifies the visual cues associated with low damage, facilitating its differentiation from similar patterns. While the current implementation employing multi-resolution segmentation and rule-based classification exhibits promising results, further optimization is acknowledged to refine the accuracy of low damage detection. The successful application of textures commonly used in rendering techniques underscores their remarkable potential for enhancing damage detection in civil engineering applications. While acknowledging limitations such as the analysis of a single cooling tower and the reliance on specific software for damage detection, the study proposes future research directions. This research holds significant implications for the field of civil engineering by offering a promising approach for automated and efficient damage detection on cooling tower shells
RESEARCH ON CONSTRUCTION TECHNOLOGY OF LARGE-DIAMETER SHIELD TUNNEL IN SHALLOW COVER SECTION OF RED STRATA GEOLOGY
Get PDFThis paper is based on the construction of the Haizhuwan Tunnel in Guangzhou, which passes through predominantly mudstone and sandstone red strata geology. Excavation is carried out using a slurry balance shield tunneling machine with both atmospheric pressure and pressurized cutterheads, and real-time excavation parameters recorded by the shield equipment are collected and statistically analyzed. Discovery: In the initial shallow-buried excavation section, the total thrust of the shield machine increased as the tunneling distance increased. By continuously adjusting the excavation parameters during construction, the shield machine gradually tended towards a stable operating state, leading to a gradual reduction in the range of thrust fluctuations. East Line: After excavating the reinforcement area, the increase in cutterhead torque is significant, leading to a more pronounced adaptation process for the shield machine. The cutterhead torque fluctuates more on rings 20 to 65 on the East Line, showing greater variability. This situation is related to the wear of the cutterhead and the condition of the shield machine equipment on the East Line. West Line: After excavating the reinforcement area, the cutterhead torque is initially reduced, with a slow and continuous increase in torque from rings 20 to 65, eventually stabilizing at around 12 MN·m. Throughout the excavation process, the shield machine on the East Line maintained a relatively high excavation speed within the reinforced soil at the face, with an average of 7.76 mm/min. As the machine excavated beyond the reinforcement area, the overall excavation speed of the shield machine slowed down. The excavation speed from ring 21 to ring 65 was primarily controlled between 2 to 6 mm/min, with an average of 4.49 mm/min, showing a relatively stable overall change
ST. VITUS CATHEDRAL AT PRAGUE CASTLE DURING THE PERIOD OF NORMALIZATION
Get PDFThis paper deals with the building modifications in the building of the Cathedral of St. Vitus, St. Wenceslas, St. Adalbert and St. Mary during the period of normalization - the 1970s and 1980s. This period has so far been neglected by researchers, although many articles and publications have been written about the history, development and artistic decoration of the cathedral. Normalization, like the entire period of communist rule in Czechoslovakia, meant the oppression of church leaders, the suppression of sacred themes in religious buildings and in everyday life. Nevertheless, the cathedral was the scene of necessary reconstruction works, as well as modifications aimed at improving the use of space and interventions based on the change of the Roman Catholic liturgy.
St. Vitus Cathedral is the most important Catholic church in the Czech Republic, formerly in Czechoslovakia, and even earlier in the Czech Kingdom. Its construction, spanning almost 700 years, demonstrates the development in culture, technical possibilities, architectural and building art. The cathedral is an essential part of the Prague Castle complex and the Hradčany panorama. Prague Castle was and still is the center of secular and ecclesiastical power. This connection was symbolically fulfilled by the most important ruler ceremonies (coronations, funerals, marriages, christenings), which took place in the cathedral.
One of the most beautiful and most photographed views of Hradčany is dominated by the silhouette of Prague Castle and especially the cathedral. The St. Vitus Cathedral rises from the base formed by the uniform design of the facades of Prague Castle, which was created during the reign of Empress Maria Theresa. For a long time the cathedral itself looked like a torso, as only the bell tower with a Renaissance and later Baroque helmet was built. The transept and the towers in the facade were not completed until the late 19th and early 20th centuries.
On the basis of archival research, interviews with witnesses and the study of specialist literature, the reader is introduced to the interventions in St. Vitus Cathedral and the associated change in the space for the celebration of the liturgy, as well as the space for ordinary visitors to this church during the period under study. Further attention is given to the unrealised designs and other sacred buildings in the grounds of the Castle
Electrical models of arcs in different applications
Get PDFThe electrical characteristic of arcs sensitively depends on many factors like electrode material and shape, working gas and gas pressure. Arc sheath voltages and electrode resistance have to be considered in particular for shorter arcs. The arc voltage behaviour is important to the switching performance. But its knowledge also allows to estimate the power consumption of the arc and the heat transferred to the electrodes. Arc voltage models are easy to integrate in power grid simulations and benefitial for the design of arc power sources. Whereas specific arc voltage models are available meanwhile for many examples, there are still knowledge gaps for arcs in a wide range of parameters. This paper provides a review of recently developed electric arc models for high and low voltage switching as well as for welding with the focus on vacuum arcs, short arcs and arcs at low current
DYNAMIC PERFORMANCE ANALYSIS OF CABLE DAMAGE IN PRESTRESSED Π-SHAPED BEAM CABLE-STAYED BRIDGE
Get PDFThis paper takes a prestressed π-shaped beam cable-stayed bridge in China as an engineering case, and conducts relevant research on the overall and local parameter sensitivity of the structure and the stress characteristics under cable damage. The main factors causing cable damage in the prestressed π-shaped beam cable-stayed bridge are analyzed, and the selection of elastic modulus as a damage variable is determined. Based on the finite element model analysis of the actual bridge, different inclined cables are selected for damage simulation, and the dynamic variation characteristics of the main beam, cables, and other structures under one-sided, symmetrical, and asymmetrical cable damage are analyzed. This provides a reference for the dynamic performance analysis of prestressed π-shaped beam cable-stayed bridges under similar cable damage conditions in the future
Driver-Car Interaction and Safety Conference 2023
No full textDCIS 2023 built on previous successful Driver-Car Interaction and Safety Conferences and represented a continuity in a good tradition of sharing actualities of research and industry in the area of driver safety and issues of human-machine interaction. The trending topic of this year\u27s conference was connected to autonomous and sustainable transport, smart cities, personal mobility and logistics. Both researchers from academia (graduate -Master and doctoral students, faculty) and experts from industry joined this event.The conference was opened to participants coming from areas of basic and/or applied research, forensic experts\u27 departments, car industries, design and ergonomics, medical research etc.
Conference presentations and discussions covered the following topics:
Human-Machine Interaction
Human factor in transportation
User needs and user acceptance
Quality methods in vehicle and vehicle systems design
Urban mobility
Transport safety
Passive and active safety of vehicles
Advanced driving simulators
Virtual reality
Computer science
Artificial intelligence
Data mining, data analysis, data classification
Driver training and driver operator
Accident analysis and prevention
Psycho-physiological measurements
Peer-review
The presented papers were peer reviewed by at least to reviewers, within a half-blind review process supervised by scientific committee.
Date: November 30, 2023Venue: Prague, Czech RepublicURL: http://www.dcis.cz/
Organized by:Department of Vehicles, Faculty of Transportation Sciences, Czech Technical University in Prague
Guest editors:Josef MíkTereza KunclováNaďa Tylová
Scientific committee:Zdeněk VotrubaPetr BouchnerJaroslav MachanStanislav NovotnýZuzana RadováAlicia KalašováLuboš NouzovskýPavel HrubešJosef KocourekIvo Drahotský
Local organizing committee:Josef MíkTereza KunclováNaďa TylováJan VálekMichal MalýPřemysl TomanJosef Svoboda
Guarantor of the peer review process: Josef Mík
Guarantor of language editing: Tereza Kunclov
Ways to identify factors contributing to the occurrence of road traffic accidents
Get PDFThe article deals with the issues of determining the factors contributing to the occurrence of road accidents. On the basis of statistical studies, the main factors most fully reflecting the process of occurrence of road traffic accidents were identified. For this purpose, an expert-statistical method was used. Road safety assessment was carried out on the example of the roads of the city of Pavlodar. The results obtained allow, in the future, to build a mathematical model that characterizes the possibility of a traffic accident