No (522)
Yes (41)
Used filters
(3)
Number of found documents:
563
Published from
to
Corrosion products phase identification using micro-Raman and FTIR
Majtás, Dušan; Mácová, Petra
2018 - English
Phase identification of corroded metal objects might be problematic because corrosion products are usually a complex mixture of different phases. Furthermore, some of present phases may be either semi-crystalline or amorphous. The most suitable procedure is to use X-ray diffraction (XRD), for identification of crystalline phases in bulk, in combination with micro-Raman spectroscopy to obtain information on smaller scale and given location. Micro-Raman spectroscopy identifies crystalline and semi-crystalline phases. The literature also reports of the application of Mössbauer spectroscopy to identify amorphous phases. In this work, the combined use of Fourier-transform infrared spectroscopy (FTIR) and Raman spectroscopy is evaluated. The methods may be interchangeable to some point. But is it safe to assume that all phases present can be detected?
Keywords:
corrosion; micro-Raman spectroscopy; FTIR
Available at various institutes of the ASCR
Corrosion products phase identification using micro-Raman and FTIR
Phase identification of corroded metal objects might be problematic because corrosion products are usually a complex mixture of different phases. Furthermore, some of present phases may be either ...
The effect of micro-silica on the microscopic features of the UHPC composite and its inter-facial transition zone
Hrbek, Vladimír; Prošek, Z.; Chylík, R.; Vráblík, L.
2018 - English
The uplift of concrete overall macroscopic performance by way of alternative additives is commonly used technique. In case of ultra high performance concrete (UHPC), micro-silica is added to the mixture as a micro-filler to the structure of cement binder. As a result, the cementitious matrix macro-mechanical performance is elevated. This paper is aimed on the UHPC micro-scale enhancement by different micro-silica additive content in the mixture. More closely, the study investigate the impact of the micro-silica on the inter-facial transition zone (ITZ) between the binder matrix and basaltic aggregate.
Keywords:
high performance concrete; indentation; spectral deconvolution SEM; image analysis; ITZ
Available at various institutes of the ASCR
The effect of micro-silica on the microscopic features of the UHPC composite and its inter-facial transition zone
The uplift of concrete overall macroscopic performance by way of alternative additives is commonly used technique. In case of ultra high performance concrete (UHPC), micro-silica is added to the ...
Design of material and technological copy for repair of sgraffito decorated renders
Válek, Jan; Skružná, Olga; Wichterlová, Z.; Waisserová, J.
2018 - English
This paper deals with research in Renaissance sgraffito materials and techniques. It focuses on the replication process for original materials and application techniques used in a reconstruction of the missing parts of a sgraffito decoration depicting a Landsknecht procession on the façade of a house in Slavonice. The result of the theoretical and practical experimental work is the description and evaluation of the process of creating a material and technological copy of the original. This involved detailed material analysis, determining the provenance of and selecting suitable raw materials, design of a repair mix and its testing, and evaluation during application trials. The study has shown that, in order to achieve good results, the conclusions of material analysis have to be linked to the practical\nskills of restorers and conservators. The particular application procedures that match the requirements of the historical material and the original work can be deduced from full scale practical trials. Feedback between the design of the repair mixture and the application process made it possible to come to an optimal material and application technique. The missing parts of the sgraffito were replaced using a mortar and application technique that closely correspond to those originally used in the Renaissance.
Keywords:
sgraffito; mortar analysis; historic techniques; Slavonice
Available at various institutes of the ASCR
Design of material and technological copy for repair of sgraffito decorated renders
This paper deals with research in Renaissance sgraffito materials and techniques. It focuses on the replication process for original materials and application techniques used in a reconstruction of ...
Forced movement of a ball in spherical cavity under kinematic excitation
Náprstek, Jiří; Fischer, Cyril
2018 - English
In the paper the response of a heavy ball rolling inside a semi-spherical cavity under horizontal kinematic excitation is investigated. The system with six degrees of freedom with three non-holonomic constraints is considered. The contact between the ball and the cavity surface is supposed to be perfect without any sliding. The mathematical model using the Appel-Gibbs function of acceleration energy is developed and discussed. The most important post-critical regimes are outlined and qualitatively evaluated on the frequency axis. Numerical experiments have been performed when excitation frequency is slowly swept up and down. Results obtained by means of semi-analytical investigation and numerical simulation are evaluated and physically interpreted. Some applications in civil engineering as a tuned mass damper used on slender structures is outlined. Strengths and weaknesses of solution method are evaluated.
Keywords:
nonlinear dynamics; non-holonomic systems; Appell-Gibbs formulation; singular states; tuned mass damper
Fulltext is available at external website.
Forced movement of a ball in spherical cavity under kinematic excitation
In the paper the response of a heavy ball rolling inside a semi-spherical cavity under horizontal kinematic excitation is investigated. The system with six degrees of freedom with three non-holonomic ...
Accuracy and numerical efficiency of approximate method for complex eigensolution of structure with specialized damping device
Hračov, Stanislav
2018 - English
The paper provides a detailed parametric analysis of the recently proposed approximate method for complex eigensolution of non-classically damped structures. This method is based on a combination of perturbation and incremental approaches and is applicable to the classically damped structures equipped with a specialized passive damping device. The numerical efficiency in terms of the required calculation times and the accuracy is demonstrated on a model of an existing structure for various combination of computational parameters. Wide numerical simulations revealed the selection of real eigenmodes of undamped system used in the approximate eigensolution as the most important parameter affecting the final accuracy.
Keywords:
non-classical damping; complex eigensolution; perturbation method; passive damper
Fulltext is available at external website.
Accuracy and numerical efficiency of approximate method for complex eigensolution of structure with specialized damping device
The paper provides a detailed parametric analysis of the recently proposed approximate method for complex eigensolution of non-classically damped structures. This method is based on a combination of ...
Influence of printing and loading direction on mechanical response in 3D printed models of human trabecular bone
Doktor, Tomáš; Kumpová, Ivana; Wroński, S.; Śniechowski, M.; Tarasiuk, J.; Forte, G.; Kytýř, Daniel
2018 - English
The paper deals with investigation on directional variations of mechanical response in 3D printed models of human trabecular bone. Sample of trabecular bone tissue was resected from human donor and 3D model was obtained by X-ray computed tomography. Then a series of cubical samples was prepared by additive manufacturing technique and tested by uniaxial compression loading mode. Mechanical response was compared in nine different combinations of direction of 3D printing and loading direction. The results show neglectible influence on the deformation response in elastic region (stiffness) and significant changes of the behaviour in plastic region (stress and strain at yield point, strain at full collapse).
Keywords:
additive manufacturing; tomography; deformation response
Available at various institutes of the ASCR
Influence of printing and loading direction on mechanical response in 3D printed models of human trabecular bone
The paper deals with investigation on directional variations of mechanical response in 3D printed models of human trabecular bone. Sample of trabecular bone tissue was resected from human donor and 3D ...
Crystallization force of sodium chloride
Koudelková, Veronika; Wolf, Benjamin
2018 - English
Soluble salts are one of the most deteriorating factor causing damage of historical building materials due to generation of crystallization pressure inside pore space. Direct measurement of crystallization force is quite challenging, hence we developed at our institute a novel device able to detect the force of growing crystal. The device is based on the monitoring of force developed with upper microscopic glass on the growing crystal to maintain constant position. The crystal could generate force because of the existence of thin liquid layer of solution between both surfaces come into contact. The driving force for the subsequent growth of crystal against obstacle is supersaturation, which is mainly induced by evaporation of the salt solution. In this experiment, the crystal of sodium chloride generated force 16.8 mN and the corresponding crystallization pressure was equal to the value 0.48 MPa.
Keywords:
crystallization force; sodium chloride; salt deterioration
Fulltext is available at external website.
Crystallization force of sodium chloride
Soluble salts are one of the most deteriorating factor causing damage of historical building materials due to generation of crystallization pressure inside pore space. Direct measurement of ...
Utilization of image and signal processing techniques for assessment of built heritage condition
Koudelka_ml., Petr; Koudelková, Veronika; Doktor, Tomáš; Kumpová, Ivana; Kytýř, Daniel; Valach, Jaroslav
2018 - English
Historical buildings represent invaluable heritage from the past and therefore their protection is a very important task. Assessment of their condition must not cause damage accumulation thus the least possible volume removed from the structure is essential. As many historical buildings in the Czech Republic are built using sandstone that can be considered as a typical heterogeneous system, statistical signal processing is a promising approach for determination of the representative volume element (RVE) dimensions. Such calculations can be carried out on the domain of logical arrays representing binary images of the materials microstructure. This paper deals with processing of image data obtained using SEM-BSE and high resolution flatbed scanner for determination of RVE dimensions. Advanced image processing techniques are employed and results from calculation using grayscale data are presented and compared with results calculated on the basis of color input images.
Keywords:
heterogeneous systems; natural stones; image processing; K-means clustering; representative volume element
Available at various institutes of the ASCR
Utilization of image and signal processing techniques for assessment of built heritage condition
Historical buildings represent invaluable heritage from the past and therefore their protection is a very important task. Assessment of their condition must not cause damage accumulation thus the ...
Multi-channel control system for in-situ laboratory loading devices
Rada, Václav; Fíla, Tomáš; Zlámal, Petr; Kytýř, Daniel; Koudelka_ml., P.
2018 - English
In recent years, open-source applications have replaced proprietary software in many fields. Especially open-source software tools based on Linux operating system have wide range of utilization. In terms of CNC solutions, an open-source system LinuxCNC can be used. However, the LinuxCNC control software and the graphical user interface (GUI) could be developed only on top of Hardware Abstraction Layer. Nevertheless, the LinuxCNC community provided Python Interface, which allows for controlling CNC machine using Python programming language, therefore whole control software can be developed in Python. The paper focuses on a development of a multi-process control software mainly for in-house developed loading devices operated at our institute. The software tool is based on the LinuxCNC Python Interface and Qt framework, which gives the software an ability to be modular and effectively adapted for various devices.
Keywords:
CNC; controlling; LinuxCNC; Python Interface; Python; parallel programming; Qt; PyQt; Qwt; PythonQwt; LabJack
Available at various institutes of the ASCR
Multi-channel control system for in-situ laboratory loading devices
In recent years, open-source applications have replaced proprietary software in many fields. Especially open-source software tools based on Linux operating system have wide range of utilization. In ...
Analysis of mini-jack technique for in situ measurement of strength
Kloiber, Michal; Tippner, J.; Kunecký, Jiří; Sebera, V.; Milch, J.; Hrivnák, Jaroslav
2017 - English
The paper presents a recently developed diagnostic technique for in situ determination of modulus of deformability (MODL) and conventional strength (CSL) parallel to the grain using the mini-jack inserted in bored hole. The mini-jack compression technique simulates the standard compression test, it is compared to that to examine its prediction strength (correlation coefficients). The paper shows an influence of moisture content of wood on experimental measurements using this technique. The measurement was carried out at spruce samples at three moisture contents of 12, 18 and 24%. The results of the tests prove a very good correlation of the strength determined by the proposed technique and wood density and strength determined at universal testing machine in compression parallel to the grain. The effect of the moisture content on the measurement by the mini-jack technique was proved to be significant. Beside that, the newly-developed instrument was also studied using digital image correlation (DIC) technique to analyze induced strains around the bored hole. This was studied on halved spruce samples. The DIC revealed symmetric character of the loading and significant differences between strains induced in tangential and longitudinal directions.
Keywords:
non-destructive testing; mini-jack technique; wood; in-situ testing; compression strength
Available at various institutes of the ASCR
Analysis of mini-jack technique for in situ measurement of strength
The paper presents a recently developed diagnostic technique for in situ determination of modulus of deformability (MODL) and conventional strength (CSL) parallel to the grain using the mini-jack ...
NRGL provides central access to information on grey literature produced in the Czech Republic in the fields of science, research and education. You can find more information about grey literature and NRGL at service web
Send your suggestions and comments to nusl@techlib.cz
Provider
Other bases