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551.
Miloš Drdácký Jaroslav Lesák Silvia Rescic Zuzana Slížková Piero Tiano Jaroslav Valach 《Materials and Structures》2012,45(4):505-520
A peeling test known as the “Scotch Tape test” has been used for more than 40 years in conservation practice for assessing
the consolidation efficiency of degraded stone. However, the method has not been supported by any standard or reliably verified
recommendations for its application. Its applicability is overestimated, and its unrestricted use without adequate knowledge
and sufficient understanding can lead to non-comparable, non-reproducible and, in many cases, incorrect and severely biased
results and assessments. This paper presents the results of a recent study focused on establishing limits for application,
reliable procedures and a “standard” protocol for testing the cohesion characteristics of brittle and quasi-brittle materials,
mainly mortars and stones. The main application strategy exploits repeated peeling in the same place on a surface in order
to eliminate the effect of the natural decrease in the detached material from the subsurface layers, which might be incorrectly
interpreted as a consolidation effect. There is a discussion of factors influencing the performance of the peeling test method,
and examples of peeling measurements on various natural and artificial stones are presented. 相似文献
552.
Dušan Galusek Katarína Ghillányová Jaroslav Sedláček Jana Kozánková Pavol Šajgalík 《Journal of the European Ceramic Society》2012,32(9):1965-1970
For various systems two-stage sintering has been reported as a successful way of suppressing the grain growth in the final stage of densification of polycrystalline ceramics. Our previous results on two-stage sintering of high purity submicrometre polycrystalline alumina indicate limited efficiency of the process with respect to suppression of grain growth. The present work deals with the influence of deliberate additions of various metal oxides (500 ppm of MgO, Y2O3 or ZrO2) whose grain growth retarding effect in conventional sintering has been well documented, on two-stage sintering of submicrometre alumina ceramics. The addition of MgO was observed to enhance densification. Addition of yttria and zirconia impaired densification, but addition of all three dopants resulted in suppression of the grain growth and microstructure refinement in comparison to undoped alumina. 相似文献
553.
Dušan Kopecký Martin Vrňata Filip Vysloužil Přemysl Fitl Ondřej Ekrt Jaromír Seidl Vladimír Myslík Jaroslav Hofmann Josef Náhlík Jan Vlček Lukáš Kučera 《Synthetic Metals》2010,160(9-10):1081-1085
The contribution deals with synthesis and characterization of conductive polypyrrole (PPY), which should be suitable for depositions of thin layers by Matrix Assisted Pulsed Laser Evaporation (MAPLE) method. The samples of doped PPY containing various organic dopants – (i) p-toluenesulfonic acid, (ii) dodecyl-benzenesulfonic acid, (iii) dioctyl-sulfosuccinic acid and (iv) camphorsulfonic acid – were synthesized by polymerization of pyrrole in acidic or neutral solution. Solubility of synthesized PPY and settlement time of PPY particles in water and dimethylsulfoxide – parameters critical for MAPLE method – were investigated. The composition of prepared PPY was verified by FTIR spectroscopy. Conductivity of the polymer in solid state was determined to be in range from σ = 2.6 × 10?6 S cm?1 to σ = 6.0 × 10?2 S cm?1. The optimal material for MAPLE deposition is PPY containing organic dopants (ii)–(iv), dissolved in DMSO matrix (solubility from 4.1% to 6.5% by weight and settlement time 140–240 h). 相似文献
554.
555.
Heat integrated heat pumping for biomass gasification processing 总被引:2,自引:0,他引:2
Martin Pavlas Petr Stehlík Jaroslav Oral Jií Kleme Jin-Kuk Kim Barry Firth 《Applied Thermal Engineering》2010,30(1):30-35
The main part of this paper is an industrial case study. It deals with an application of a heat pump in energy systems for biomass gasification in a wood processing plant. Process integration methodology is applied to deal with complex design interactions as many streams requiring heating and cooling are involved in the energy recovery. A refrigeration cycle maintains low temperature in the scrubber where the production gas (or synthesis gas–syngas) is cooled and undesirable contaminants are removed before the syngas is introduced into the engine. In addition to electricity generation, a large amount of waste heat is available in the biomass gasification system studied in the paper, and its appropriate heat integration with utility systems within a plant allows the available heat to be efficiently utilized for the site. The conceptual understanding gained from the case study provides systematic design guidelines for further process development and industrial implementation in practice. 相似文献
556.
Natalia V. Blinova Stéphanie Reynaud François Roby Miroslava Trchová Jaroslav Stejskal 《Synthetic Metals》2010,160(15-16):1598-1602
Polystyrene latex particles were swollen with aniline and subsequently exposed to ammonium peroxydisulfate solution. The polyaniline membrane was produced at the particle interface and separated both reactants. The electrons from aniline monomer are transferred to oxidant molecules through conducting polyaniline membrane. The aniline and peroxydisulfate thus react without the need to physically meet. Polyaniline gradually penetrated inside latex particle, in contrast to core–shell morphology obtained in classical coating of latex particles with polyaniline. 相似文献
557.
Jamie J. Gengler Jianjun Hu John G. Jones Andrey A. Voevodin Petr Steidl Jaroslav Vl?ek 《Surface & coatings technology》2011,206(7):2030
In this study, thermal transport was investigated for ceramic films with different silicon, boron, carbon, and nitrogen (Si–B–C–N) compositions. In order to investigate the effect of morphology on thermal barrier properties, the microstructure of these materials was varied from amorphous to nanocrystalline. Thermal conductivity trends of several ceramic thin films were characterized with a time-domain thermoreflectance (TDTR) technique. Samples containing two different Si–B–C–N chemical compositions were created by reactive magnetron sputtering and then subjected to annealing at temperatures up to 1400 °C. The room temperature thermal conductivity of the samples prepared via a 50% Ar/50% N2 gas mixture remained constant near 1.3 W m−1 K−1, while samples prepared via a 75% Ar/25% N2 gas mixture exhibited an increase in the thermal conductivity of 2.2 W m−1 K−1 (or higher). X-ray diffraction data demonstrated that the former samples were amorphous, while the latter samples formed silicon nitride (Si3N4) crystals. The experiments reveal which Si–B–C–N film composition remains stable in the amorphous state at high temperatures, thereby retaining lower thermal transport properties. These material aspects are ideal for thermal barrier applications such as non-oxide based ceramic coatings for high-temperature protective systems of aircrafts, as well as surfaces of cutting tools and optical devices. 相似文献
558.
Kamila Havlíčková Jan Weger Jaroslav Knápek 《Simulation Modelling Practice and Theory》2011,19(9):1946-1956
The article combines theoretical approaches in economic modelling with practical application of created models for the bio-energy sector in the defined area. Design and application of economic models is discussed to predict future biomass prices from new energy crops on the developed and saturated bio-energy market. The models use minimum price methodology based on application of elementary principles of economic theory to commercial activity with undeveloped production and/or the demand side of the biomass market. The model is then tested on real economic and agronomic data from pilot and experimental biomass production and utilization projects in the Czech Republic with a case study of biomass from poplar and willow short rotation coppice (SRC) and reed canary grass plantations. Selected results of this modelling of biomass prices are presented and discussed. The economic model created proved to be a practical tool for analysis of the effectiveness and competitiveness of biomass from different energy crops on the energy market, which can be used for strategic planning on the part of state administration or decision-making of companies in the biomass sector. 相似文献
559.
Elena N Konyushenko Jaroslav Stejskal Miroslava Trchová Jan Prokeš 《Polymer International》2011,60(5):794-797
The oxidation of aniline hydrochloride by ammonium peroxydisulfate in non‐aqueous media was studied, when the monomer or oxidant or both were not completely soluble. Polyaniline was formed in acetone, methanol and toluene. Aniline oligomers only were produced in chloroform and n‐butylacetate. No interaction of the monomer and the oxidant was observed in dimethylsulfoxide and N‐methylpyrrolidone. UV‐visible and Fourier transform infrared spectra were recorded in order to study the molecular structure of the final products. Conductivity was measured for conducting protonated forms and corresponding bases. An explanation of aniline hydrochloride oxidation in various organic media is offered. Copyright © 2011 Society of Chemical Industry 相似文献
560.
This work presents an algorithm for the development of adaptive soft sensors. The method is based on the local learning framework, where locally valid models are built and maintained. In this framework, it is possible to model nonlinear relationship between the input and output data by the means of a combination of linear models. The method provides the possibility to perform adaptation at two levels: (i) recursive adaptation of the local models and (ii) the adaptation of the combination weights. The dataset used for evaluation of the algorithm describes a polymerization reactor where the target value is a simulated catalyst activity in the reactor. This dataset is also used to evaluate the performance of the proposed algorithm. The results show that the traditional recursive partial least squares algorithm struggles to deliver accurate predictions. In contrast to this, by exploiting the two‐level adaptation scheme, the proposed algorithm delivers more accurate results. © 2010 American Institute of Chemical Engineers AIChE J, 57, 2011 相似文献