No (7623)
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7623
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Survey of the use of propane as refrigerant R290 in cooling circuits and heat pumps
Aminian, Ali; Prokopová, Olga; Vinš, Václav
2022 - English
The technical report presents a review on the application of propane as refrigerant R290 in cooling circuits and heat pumps (HVAC). Safety risks of R290 used in HVAC are addressed according to ANSI/ASHRAE and EN standards. Comparison of thermophysical properties of propane with other refrigerants, solubility and miscibility of propane in compressor oils and heat transfer in condenser and evaporator are discussed. The main aim of the study is to provide an overview about the potential use of propane in the cooling circuit and heat pump for the hydrogen bus developed by the SOR Libchavy company.
Keywords:
cooling circuit; heat pump; hydrogen bus; refrigerant
Available at various institutes of the ASCR
Survey of the use of propane as refrigerant R290 in cooling circuits and heat pumps
The technical report presents a review on the application of propane as refrigerant R290 in cooling circuits and heat pumps (HVAC). Safety risks of R290 used in HVAC are addressed according to ...
Identification of material constants of rubber damping segments by modal analysis for railway rubber-resilient wheels
Šulc, Petr; Šnábl, Pavel; Pešek, Luděk; Bula, Vítězslav
2022 - English
In this paper, an experimental and numerical modal analysis is described to assess two rubber compounds for the damping segments of a railway wheel. The subject of this comparison is materiál parameters such as Young’s modulus and loss factor for both compounds in the frequency range up to 6.5 kHz. From this comparison, an idea of the damping, stiffness and durability of these rubber segment materials inside these wheels is obtained.
Keywords:
modal analysis; rubber; railway wheel; damping segment
Available at various institutes of the ASCR
Identification of material constants of rubber damping segments by modal analysis for railway rubber-resilient wheels
In this paper, an experimental and numerical modal analysis is described to assess two rubber compounds for the damping segments of a railway wheel. The subject of this comparison is materiál ...
Stone surface topography of Prague historic monuments over the centuries
Kovářová, K.; Cihla, Michal; Malát, R.; Semerád, M.; Tryml, M.
2022 - English
Stonemasons tool traces on stone surface are undoubtably a significant part of monument historic value. As any other profession, stonemasons craft develops over time and has its own specifics in every period. Each work has its own unique pattern and bears traces of individual stonemason workshops, tradition, etc. The study of building stone cutting is based on evolving methods of mechanoscopy and analytical traceology. Stone traceology deals with traces in material and the subsequent reconstruction of tools and the processes of stoneworking. The interpretation of data in terms of determining the actual trace is called a mechanoscopy. When studying a stone surface, the latest 3D modelling technology is used with subsequent analyses by means of Global Mapper software. The use of these methods enables reconstruction of the craftsman’s tools. The presented article is an extract of a study that systematically maps the stone cutting work in the territory of Prague from the oldest buildings to the present day. For example, stonework in 9th century Prague was gradually evolving from simple stone block modelling to sophisticated cutting of blocks in the 12th century. This information can be very useful in the process of monument care.
Keywords:
stone topography; Prague; craftmanship; stonemason tool; tool traces
Available at various institutes of the ASCR
Stone surface topography of Prague historic monuments over the centuries
Stonemasons tool traces on stone surface are undoubtably a significant part of monument historic value. As any other profession, stonemasons craft develops over time and has its own specifics in every ...
A Measure of Variability WIthin Parametric Families of Continuous Distributions
Fabián, Zdeněk
2022 - English
A continuous probability measure on an open interval of the real line induces in it a unique geometry, "center of gravity" of which is the typical value of the distribution. In the paper is identified a score variance as a finite measure of variability of distributions with respect to the typical value and discussed its properties and methods of estimation. Itroducing a generalized Rao distance in the sample space one can appraise the precision of the estimate of the typical value.
Keywords:
scalar-valued score; score mean; score variance; distance in the sample space
Available at various institutes of the ASCR
A Measure of Variability WIthin Parametric Families of Continuous Distributions
A continuous probability measure on an open interval of the real line induces in it a unique geometry, "center of gravity" of which is the typical value of the distribution. In the paper is identified ...
Creep of oak dowel: various loading and environmental conditions
Hasníková, Hana; Kunecký, Jiří; Hataj, M.
2022 - English
For research of timber joints, the crucial role in force distribution inside the joint is played by distribution and variability of stiffness of the dowels. Not only the instant stiffness, but the one that we can encounter after some longer period. Also, this value and its statistical distribution is influenced by many other factors, however, humidity and temperature are in timber (oak) dowels of utmost importance. In the work results of a creep experiment made using a special testing rig is presented. It has been found, that biggest changes in creep behavior are in case if very humid conditions are present, and, also, that cycling the temperature in high humidity conditions can produce about 104% of the original instantaneous displacement. The result is not surprising, however, new insights are made thanks to relatively high number of samples and ability to produce some statistics. Another outcome is relation of dowel stiffness in time to the level of applied stress, which is quantified in the article.
Keywords:
oak dowel; creep; humidity
Available at various institutes of the ASCR
Creep of oak dowel: various loading and environmental conditions
For research of timber joints, the crucial role in force distribution inside the joint is played by distribution and variability of stiffness of the dowels. Not only the instant stiffness, but the one ...
Proceedings of the SHATIS 2022 – 6th International conference on structural health assessment of timber structures
Kunecký, Jiří; Hasníková, Hana
2022 - English
Structural health assessment of timber structures associates various procedures in order to evaluate the safety and serviceability of structures. Also, it helps to assure or extend the predicted service life of structures. Service life sustainability can be promoted by the incorporation of monitoring systems or by providing tools and methods that deliver accurate reports about the structural condition. Conservation and assessment of timber structures is based on a multidisciplinary approach. The conference topics cover the wide spectrum, from wood properties, through performance of joints and timber design, to modern monitoring and digital technologies. As the topics include both existing and historical timber structures, the need for reliable non destructive testing methods is part of the approach as well.
Keywords:
timber structures; monitoring and survey; design
Available at various institutes of the ASCR
Proceedings of the SHATIS 2022 – 6th International conference on structural health assessment of timber structures
Structural health assessment of timber structures associates various procedures in order to evaluate the safety and serviceability of structures. Also, it helps to assure or extend the predicted ...
Score correlation for skewed distributions
Fabián, Zdeněk
2022 - English
Based on the new concept of the scalar-valued score function of continuous distributions we introduce the score correlation coefficient ”tai-lored” to the assumed probabilistic model and study its properties by means of simulation experiments. It appeared that the new correlation method is useful for enormously skewed distributions.
Keywords:
Scalar-valued score; score coefficient of variation; Monte Carlo
Available at various institutes of the ASCR
Score correlation for skewed distributions
Based on the new concept of the scalar-valued score function of continuous distributions we introduce the score correlation coefficient ”tai-lored” to the assumed probabilistic model and study its ...
Introduction to statistical inference based on scalar-valued scores
Fabián, Zdeněk
2022 - English
In the report we maintain consistently the following point of view: Given a continuous model, there are not the observed values, which are to be used in probabilistic and statistical considerations, but their ”treated forms”,the values of the scalar-valued score function corresponding to the model. Based on this modified concept of the score function, we develop theory of score random variables, study their geometry and define their new characteristics, finite even in cases of heavy-tailed models. A generalization for parametric families provides a new approach to parametric point estimation.
Keywords:
continuous distributions; score mean; score variance; score moment estimation method; score distance
Available at various institutes of the ASCR
Introduction to statistical inference based on scalar-valued scores
In the report we maintain consistently the following point of view: Given a continuous model, there are not the observed values, which are to be used in probabilistic and statistical considerations, ...
Scalar-Valued Score Functions and their use in Parametric Estimation
Fabián, Zdeněk
2022 - English
In the paper we describe and explain a new direction in probabilistic and statistical reasoning, the approach based on scalar-valued score functions of continuous random variables. We show basic properties of score functions of standard distributions, generalize the approach for parametric families and show how to use them for solutions of problems of parametric statistics.
Keywords:
core random variable; score mean; score variance; score distance; score correlation
Available on request at various institutes of the ASCR
Scalar-Valued Score Functions and their use in Parametric Estimation
In the paper we describe and explain a new direction in probabilistic and statistical reasoning, the approach based on scalar-valued score functions of continuous random variables. We show basic ...
Measurement on Compressor Cascade KOBRA
Luxa, Martin; Šimurda, David
2022 - English
The report contains results and evaluation of conducted optical (shadowgraph and schlieren technique) and pneumatic measurements on the profile cascade intended for the tip section of the first rotor row compressor blade.
Keywords:
compressor cascade; transonic flow; optical measurement; pneumatic measurement
Available at various institutes of the ASCR
Measurement on Compressor Cascade KOBRA
The report contains results and evaluation of conducted optical (shadowgraph and schlieren technique) and pneumatic measurements on the profile cascade intended for the tip section of the first rotor ...
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