CTU Open Journal Systems (Czech Technical University, Prague / České vysoké učení technické v Praze)
Not a member yet
4735 research outputs found
Sort by
Emanuel Šlechta, engineer and entrepreneur in the First Republic of Czechoslovakia
Get PDFThis article traces the political, economic, and technical activities of Professor Emanuel Šlechta in the pre-war period and just after 1945. The aim is to answer the question: “What were Emanuel Šlechta’s activities during the First Republic and how did they help him in his later role as Czechoslovak Minister of Technology?” The text covers in chronological order the period between the two world wars, when Šlechta completed his technical studies in Prague and completed an internship in industrial factories in the USA, then gained crucial experience in the Bata concern, and gradually developed into an important national economist and expert in the field of labour organisation. This led to his appointment as a minister after World War II
Strategic management of the portfolio of urban real estate: research of the current scientific knowledge
Get PDFMunicipalities possess a wide range of real estate. However, land, buildings, and premises must not only be managed individually, but also optimized and strategically developed as a comprehensive portfolio linked to the objectives of public administration activities and, of course, to the development plans of a particular municipality. Nevertheless, a comprehensive view of the issue of managing and building a real estate portfolio in public administration is missing. This is evidenced by the lack of a methodology that would help local authorities with the task. Thus, a quantitative analysis of scientific publications was conducted, dealing with the issue of strategic management of real estate portfolios at the city level, both within the Czech Republic and throughout the world. This article aims to present a qualitative search of the content of scientific publications, thereby contributing to the creation of a foundation for further systematic research into this issue
Preparation of light fraction silicate filer after the mining for the base layers’ road construction
Get PDFThe article main objective was eco-innovation in the field of utilization and creation of a complex waste-free technology for the separation of components during ore extraction with subsequent processing, recovery of mine tailings in combination with available energy. The article deals with the topic of production and preparation of base layers for road construction in the form of silicate filer after separation of ore mining. The chemical and mineralogical composition on the fine fraction of the separated tailings was carried out by XRD analysis, filer particle size followed up by Laser Granulometry and other comprehensive measurements and the development of basic parameters by individual standard tests. The results determined on the functional sample demonstrated that it is possible to create an almost completely waste-free technology in the field of separation of components during ore extraction and its subsequent processing and use for the base layers of linear road construction
Concrete mixtures with photovoltaic panels glass: a review of the situation in Czech Republic
Get PDFSolar energy production was initiated in the 1990s following by rapid increase of the use of photovoltaic (PV) technology. Most of older solar panels in the Czech Republic were installed between 2000 and 2006 and a global installed capacity of 222 GW was reached by the end of 2015. With the growing global PV market, a large amount of waste is expected to accumulate after 2030 which is associated with the new industry to process this waste, based on reduce, reuse, and recycle. This article summarizes findings and research conclusions regarding local issues collected by experts from the Czech Republic. Previous research showed that waste glass from photovoltaic panels can be used as a pozzolanic material in high-performance concrete, improving its properties. Further research on the use of waste from photovoltaic panels has been conducted in the Czech Republic since 2019 and the conclusions from various research confirm the suitability of using PV panel glass
Construction Technology and Application of TBM in Shengli Tunnel of Tianshan Mountain under poor geological conditions
Get PDF When a tunnel boring machine (TBM) excavates in poor geological conditions like fracture zones, soft rock with high ground stress, hard rock with high ground stress, and water inrush ground, severe problems such as surrounding rock collapse, convergence, rock burst and water and mud outburst are usually encountered. These problems existed in the Tianshan Shengli Tunnel project in Xinjiang, China. Several methods and techniques were adopted to reduce construction risks and improve construction efficiency. The seismic wave reflection long-distance geological forecasting method was employed to forecast and predict these adverse geological conditions. The pre-reinforcement construction method was employed on the surrounding broken rocks in front of the tunnel face to lower the risks of tunnel collapse and machine jamming. A combined steel arch was applied to prevent tunnel arch collapse. An artificial cap method was applied to prevent the jamming caused by high-ground stress soft rock. Measures such as spraying water on the tunnel face and drilling stress holes were employed to prevent rock bursts caused by high-ground stress in hard rock. Implementing the advanced pipe shed method during water influx, sudden mud, and other working conditions reduced the risk of groundwater damage to equipment and lowered risks to personnel safety. The successful application of these techniques can provide a reference for TBM tunnel construction in similar ground conditions
DIGITALIZATION OF IRRIGATION SYSTEMS FROM WATER MANAGEMENT MAPS
Get PDFWith the increasing intensity of evapotranspiration caused by the changing climate, there is a growing need for water. This is especially true in locations where water-intensive vegetables are grown in intensive agriculture. Historically, irrigation systems were built in many intensive agriculture areas in Czechia, but they fell out of use, and evidence of their location was lost. However, Water Management Maps, which were only issued in paper form and have never been fully digitized, can provide evidence about the location of these large-scale irrigation systems. In this paper, we present a method for digitizing irrigation systems using the segmentation and classification of individual segments in the ArcGIS environment. The resulting raster is converted to polygons and is blended with the Land Parcel Identification System layer, resulting in a layer of irrigated land. Two statistical analyses were performed on this layer: statistics of the areas corresponding to the individual source watercourses, and statistics of the type of source
Study of ozone destruction reaction on surfaces
Get PDFThe ozone destruction was studied in a quartz cuvette. The time dependence of ozone concentration was measured by absorption spectroscopy. From this time dependence the pseudo first-order rate constant was derived. This rate constant depends on surface condition - the surface concentration of adsorbed oxygen atoms. This surface concentration was changed by reactions of adsorbed oxygen atoms with gaseous molecular oxygen just before the cuvette was filled by ozone. The decrease of atomic oxygen surface concentration leads to the decrease of rate constant for ozone destruction. The measured rate constants were in range 9.0 × 10−5 s−1 to 9.8 × 10−5 s−1
Design of a network of cycling routes in the Kutná Hora district
Get PDFCycling is a dynamically expanding transport mode of today. At the same time, cycling is an alternative to individual car transport as well as to public transport. The basis of a good cycling infrastructure is a comprehensive network of safe cycling routes linking transport sources and destinations in the area. The partial objectives of the project are to evaluate the management of the existing cycle routes according to the way cyclists are guided and according to the surface of the individual route sections, as well as to determine the basic sources and destinations. The main objectives of the project are to design a network of bicycle routes with a focus on keeping them separate from motorized traffic and linking the identified resources and destinations, as well as determining thedifficulty of each newly proposed route
Effect of aging on mechanical properties of 3D printed samples using stereolitography
Get PDFThis paper focuses on stereolithography (an additive manufacturing technology working on the principle of curing liquid resins layer by layer using ultraviolet radiation) and the effect of aging on the mechanical properties of the material and printed samples. The aging of the material could be a problem for its subsequent use as the stability of the mechanical properties would not be maintained and unwanted deterioration of the material could occur. As part of the research, sets of samples were printed and subjected to different aging methods and subsequently subjected to quasi-static and dynamic uni-axial load tests. From the data obtained, the basic mechanical properties of the material were calculated and compared with each other. The aim of this paper was to investigate whether aging process causes significant changes in the mechanical properties of the materials used, which could have a consequential impact on their use in different industries
Simulation of a multimaterial model for modified auxetic structures
Get PDFAuxetic structures, which is a term used to describe materials with a negative Poisson’s ratio, show beneficial properties like a low density, a high energy absorption capacity and an increased indentation resistance. This enables applications in many fields, such as aerospace and sports industries. Given their potential, many studies have already been conducted. Previously, the geometry of a selected auxetic re-entrant structure was optimized to maximize its mass-specific energy absorption capacity for ideal usage in lightweight applications. Moreover, a homogeneous material was used, whereas the combination of multiple materials could drastically increase the performance of such structures. Hence, in this study the use of two different materials combined into a modified re-entrant structure is investigated via Finite Element simulation. The Poisson’s ratio could thus be improved, which leads toa more pronounced and longer lasting auxetic effect