CTU Open Journal Systems (Czech Technical University, Prague / České vysoké učení technické v Praze)
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The Evolution of Cinemas in Prague from the Second Half of the Twentieth Century: A Contemporary Perspective
No full textČlánek přibližuje situaci pražských kin v druhé polovině 20. století v rámci společensko-historického pozadí z pohledu architekta a cinefila. Zaměřuje se především na nově vzniklá kina v tomto období, z nichž je v současnosti funkční už jen jediné – kino Dlabačov na pražském Břevnově. Práce je členěna chronologicky do odstavců dle jednotlivých etap, které reflektují míru svobody tvorby, danou tehdejším politickým uspořádáním a vlivy, prosakujícími do Československa ze zahraničí. Pokrývá dobu od konce druhé světové války až po sametovou revoluci. Poslední kapitola je věnována kinu Dlabačov. Výzkum má ambici pochopit a přiblížit, jak začlenit hodnotné budovy kin na území Prahy do každodenního života současného Pražana skrze zkoumání fenoménu kina, a vývoje kinematografie a architektury kin jako takové, od jeho vzniku až po současnost. Všeobecnými logickými metodami zpracování jsou analýza, historický exkurz, porovnání a dedukce.The article approaches the situation of Prague cinemas in the second half of the 20th century from the end of the Second World War to the Velvet Revolution within the socio-historical background from the point of view of an architect and a cinephile. The entire text is arranged chronologically in four paragraphs reflecting the contemporary political and social situation. It approximates the post-war period full of ideological ideals, when the construction of a dense network of cinemas became a key element of national renewal, not only in large cities but also in the regions. The following decade brought a paradigmatic shift, when local single-screen cinemas gave way to large cultural houses with multifunctional use (film, theatre, gallery, restaurant, sports facilities, etc.). It deals with the socially relaxed sixties, reflecting the synergy of various artistic disciplines, thanks to which Czechoslovakia presented to the world new artistic disciplines based precisely on film projection – “polyekran” (polyscreen) and “laterna magika” (a combination of projection and performance with live actors). The imaginary culmination of the new wave period was the opening of the luxury cinema 64 U Hradeb, which is given more attention in the text below. Furthermore, the text outlines the situation of cinemas in large Prague housing estates and deals with Czech brutalism in the context of foreign architecture and with the only brutalist cinema still operating today – the Dlabačov cinema. The final part of this article gives a brief overview of the total number of cinemas established in this period in the territory of Prague and a comparison with other European metropolises with a similar socio-cultural background. The research has the ambition to understand and approach how to integrate valuable cinema buildings on the territory of Prague into the daily life of contemporary Prague residents through the investigation of the cinema phenomenon, and the development of cinematography and cinema architecture as such, from its inception to the present day. The general logical processing methods are historical and socio-cultural analysis, architectural and urban research including architectural drawings, photographic documentation and a study of the urban development of the appearance of individual cinemas, comparison and deduction
An elastoplastic constitutive model of lunar soil simulant considering shear dilatancy and softening characteristics
Get PDFThe study of the constitutive relationship of lunar soil is the key to a deep understanding of the mechanical properties of lunar soil and the subsequent construction of lunar bases. Previous models mostly focused on the strengthening behavior before the peak, while rarely reflected the post-peak softening and residual deformation stages during shear deformation. A new elastoplastic constitutive relation is derived with combining kinematic hardening model and initial shear stress, which effectively compensates for the shortcomings of existing constitutive models, and the validity of the model is verified by comparing with existed laboratory test results. The developed constitutive model not only effectively captures the shear dilatancy and softening characteristics of lunar soil simulant, but also requires fewer parameters to be easily determined by simple initial loading curves from direct shear tests, Furthermore, the influences of some key parameters on shear strength and softening behavior of lunar soil simulant can be easily obtained based on this constitutive model
RESEARCH ON OPTIMIZATION OF MOTORWAY ROUTE DESIGN SCHEME IN MOUNTAIN AREAS BASED ON ENTROPY WEIGHT-TOPSIS MODEL
Get PDFDuring the design process of a new mountainous motorways, multiple route schemes are often proposed for a comprehensive design effort. Each route scheme will have its advantages and disadvantages, so it is often difficult to choose a route scheme. Usually the expert decision method is used to screen the route schemes, but this method mainly relies on the personal experience of experts, and it is difficult to measure the criteria, which can lead to the embarrassing situation that different experts do not agree on the choice of routes.In order to optimize the route scheme for the design process of mountainous motorways and improve the efficiency and scientificity of route scheme selection, evaluation indicators were selected from traffic safety, construction economy, and environmental friendliness. The Entropy Weight Method (EWM) was used to assign the weight of the evaluation indicators. By improving the Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS), the problem of subjective opinions and excessive reliance on objective data by designers in the multi factor evaluation process was overcome. A EWM-TOPSIS evaluation model was proposed. By analyzing specific examples of mountainous motorway construction, research results were obtained. The results indicate that the model can reflect the designer\u27s intention towards the route scheme and the actual construction project. There is a high degree of consistency with the expert\u27s empirical judgment, which verifies the feasibility and accuracy of the model. This model can provide reliable reference and basis for the decision-making of motorway route schemes in mountainous areas
Possibilities of replacing natural sand in concrete
Get PDFThis study explores the potential of using fine recycled aggregate (FRA) to replace natural sand in concrete production. The research was divided into two parts. In the first part, natural aggregate’s complete fine fraction (0‑4 mm) was replaced with FRA in conventional concrete for two strength classes. In the second part, individual fine components of high-performance concrete (HPC) were substituted with a similar fraction of fine recycled HPC and concrete aggregate. The physical and mechanical properties of these mixtures with recycled aggregate were evaluated against reference mixtures that contained only natural aggregate, following European standards. Results showed that while most of the concrete and HPC mixtures with recycled aggregate showed slight decreases in properties compared to the reference mixes, the most significant reduction in mechanical properties was observed in the flexural tensile strength of the concrete mixture with FRA, which decreased by over 50 %. The absorption by immersion increased by up to 85 %. The deterioration in properties must be considered during the design stage and only used in applications where it will not affect the functionality of the structures
Effect of preparation process on purity of tricalcium aluminate
Get PDFIn the realm of cement production, traditional fuels are steadily giving way to alternative sources. While this shift yields economic and ecological advantages, it introduces notable technological challenges. Specifically, there is an escalation in certain chemical elements, leading to variability in the mineralogical composition. This variability is subsequently manifested in the characteristics of Portland clinker. It becomes imperative, therefore, to synthesize pure clinker minerals. This synthesis is essential for both understanding their behavior in industrially manufactured cement and creating analytical standards for mineral identification through XRD. The primary focus of the research is on the production of pure tricalcium aluminate, a key clinker mineral, within laboratory conditions. A direct laboratory methodology involving solid-phase synthesis is used. The investigation meticulously tracks the impact of homogenizing the raw material mixture on the resultant mineral’s purity. To achieve this, a high-speed Pulverisette 6 planetary mill is utilized along with two types of grinding bodies. A corundum grinding capsule with corundum grinding bodies is employed to prevent contamination by foreign ions. Simultaneously, a highly efficient steel grinding capsule with steel grinding bodies is utilized. The raw material mixture is then subjected to sintering at six different temperatures ranging from 1 200 to 1 450 °C, and the purity of the produced mineral is quantified using Rietveld analysis. Laser granulometry results indicate a strikingly similar comminution of the raw material in both grinding cases. Iron contamination, as revealed by XRF analysis, is minimal, accounting for only 0.21 %. The purity of 97.6% C3A, is achieved at 1 450 °C using a steel grinding capsule, with 2.4% unreacted lime Conversely, when using a corundum capsule, a purity of 93.6 % is achieved, accompanied by residues of 2.2 % mayenite and 3.8 % lime. This discrepancy may be attributed to an insufficient degree of raw material comminution in the corundum capsule. Intriguingly, a slight iron contamination during the grinding of the raw material mixture exerts a positive influence on purity. In this case, iron acts as a flux, fostering a more favorable reaction of the mineral mayenite. This multifaceted exploration enhances our understanding of clinker mineral synthesis, offering insights into optimizing purity based on grinding methods, sintering temperatures, and the impact of minor contaminants
The carbonation resistance of concrete on the basis of blended binders containing milled limestone
Get PDFThe current building industry is essentially changing due to implementation of new approach, which is predominantly motivated by the need to reduce its negative environmental impact. The paper is focused on the experimental evaluation of carbonation resistance in terms of accelerated tests performed on the concrete on the basis of blended binding system incorporating milled limestone. The used commercially produced cement was additionally modified by the limestone powder. The obtained results confirmed, that currently used design standards are convenient to real carbonation process, however further clinker replacement by the milled limestone causes significant loss of the durability of the hardened concrete
Flat roof classification and leaks detections by Deep Learning
Get PDFThis paper presents an efficient and accurate method for detecting flat roof leaks using a combination of unmanned aerial vehicles (UAVs) and deep learning. The proposed method utilizes a DJI M300 drone equipped with RGB and thermal cameras to capture high-resolution images of the roof. These images are then processed to create orthomosaics and digital elevation models (DEMs). A deep learning model based on the U-NET architecture is then used to segment the roof into different classes, such as PVC foil, windows, and sidewalks. Finally, the damaged insulation is identified by analyzing the temperature distribution within the PVC foil segments. The proposed method has several advantages over traditional inspection methods. It is much faster and more efficient. A UAV can collect images of a large roof in a matter of minutes, while traditional methods can take several days or weeks. The orthomosaics and temperature maps generated by the UAV are much more detailed than the images that can be collected by a human inspector. Third, the UAV-based system is safer. The UAV can collect images of the roof without the need for a human inspector to climb onto the roof, which can be dangerous. The results of this study show that the proposed method is an effective and accurate way to detect flat roof leaks. The deep learning model was able to achieve an overall accuracy of 95% in segmenting the roof into different classes. The method was also able to identify damaged insulation with a high degree of accuracy
Investigation of the impact of product thickness and strain on cold forging processes
Get PDFThis study investigates the impact of sheet metal thickness and strain generated on a cold forging process. A cold forging die was manufactured based on a numerically modelled product design that considered stress concentration die profiles. Experiments involved cold forging various sheet metals (lead, brass, aluminium, and steel) with thicknesses ranging from 2mm to 6mm to assess their influence on the thickness and strain. An assumption was formulated using Solidworks to determine the appropriate sheet metal thickness based on the material type. This assumption, based on volume considerations, showed practical applicability for selecting sheet metals with thicknesses close to those designed in the numerical modelling. The results revealed that softer materials, such as lead and aluminium, closely approximated the design thickness, particularly in the central region of the die profile, with error deviations of 1.14 % and 4.36 %, respectively. In contrast, harder materials demonstrated larger deviations from the design, with minimum errors of 4.94 % for brass and 5.73 % for steel. All sheet metals underwent compressive strain in the central region of the die profile due to the stamping operation. This work demonstrates a practical approach for selecting sheet metals based on material and thickness considerations, providing insights into the behaviour of different materials during the cold forging process
The effect of the inlet chamber and diffuser on the reverse aerodynamic performance of an axial flow fan
Get PDFFlow reversal in axial fans is usually carried out by changing the direction of rotation of the fan and rotating the stator vanes. The total pressure losses of selected inlet fan chambers were determined using CFD data for the normal and reverse flow conditions. These losses are 3.5 to 7.2 times greater for the normal flow increase due to the flow reversal in three chambers with the hub/tip ratio of 0.45 to 0.63. The operating points of two complete fans made up of the inlet chamber, the diffuser, and the axial stages A and B with different aerodynamic load were obtained using one-dimensional engineering calculation method. It uses the measured performance data relating to both fan stages. The calculated volumetric flow rate ratio for reverse and normal operation is 0.68 and 0.55, respectively, for the complete axial fan with the stages A and B. The acquired results are in accordance with the customers’ requirements
Drece method for continuous severe plastic deformation of CuZn37 sheets
Get PDFThis paper presents a continuous severe plastic deformation (SPD) process for sheet metal called Dual Rolls Equal Channel Extrusion (DRECE) is introduced. The DRECE process achieves maximum sheet metal deformation by combining bending deformation with channel-angular shear deformation. The evolution of the microstructure and mechanical properties of the CuZn37 alloy has been experimentally investigated as a function of the number of repeated DRECE passes. The DRECE process was repeated up to four times at room temperature. As the number of passes increased, the character of the microstructure was gradually strongly deformed by intensive shear deformation. The microhardness and tensile properties changed significantly as a function of the number of repeated passes