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101.
Effect of thermal decomposition processes on the thermal properties of carbon fiber reinforced cement composites in high-temperature range 总被引:1,自引:0,他引:1
R. Černý Jitka Němečková Pavla Rovnaníková P. Bayer 《Journal of Thermal Analysis and Calorimetry》2007,90(2):475-488
Thermal conductivity, specific heat capacity, thermal diffusivity and linear thermal expansion coefficient of two types of
carbon fiber reinforced cement composites are measured in the temperature range up to 800°C. Thermal conductivity and thermal
diffusivity are also determined for the specimens exposed to thermal load up to 800°C before the measurement. Differential
thermal analysis (DTA), mercury intrusion porosimetry (MIP), scanning electron microscopy (SEM) and X-ray diffraction analysis
(XRD) are utilized for the assessment of thermal decomposition processes taking place in the high temperature range under
consideration.
The high temperature thermal properties of the studied materials are found to be positively affected by the application of
the high alumina cement and in the case of the Portland cement based composite also by using the autoclaving procedure in
the production process. Also, the randomly distributed carbon fibers that can reduce the damage of the pore structure by the
thermal decomposition processes are identified as a positive factor in this respect. A comparison of thermal conductivity
vs. temperature curves obtained for the specimens pre-heated to different temperatures is found to be a useful tool in the identification
of major dynamic effects in the specimens due to the thermal decomposition reactions. The results are in a good agreement
with the DTA, MIP, SEM and XRD analyses. The character of the thermal conductivity measurements that in fact includes the
effects of convection and radiation into the thermal conductivity coefficient can be beneficial for a simple assessment of
the influence of the fire on a dividing structure. 相似文献
102.
Egorova A. V. Viktorov N. B. Starova G. L. Dogadina A. V. 《Russian Journal of General Chemistry》2019,89(9):1765-1771
Russian Journal of General Chemistry - The reaction of dialkyl 2-[(dialkoxyphosphoryl)ethynyl]-2-(arylamino)malonates with bases (CH3COOK, t-BuOK) can serve as a method for preparing original... 相似文献
103.
A. A. Anikeev S. B. Viktorov S. A. Gubin 《Russian Journal of Physical Chemistry B, Focus on Physics》2014,8(1):56-60
A numerical modeling of the thermodynamic properties of a fluid is performed using the method of integral equations. The predictions are compared with the results of MC and MD simulations. The problem of stability of the numerical solution is examined. The methods for correcting the correlation functions and for estimating their uncertainties are proposed. 相似文献
104.
S. I. Bityukov G. V. Borisov V. A. Dorofeev R. I. Dzhelyadin S. V. Golovkin M. V. Gritzuk A. S. Konstantinov V. P. Kubarovski N. Yu. Kul'man A. I. Kulyavtzev V. F. Kurshetzov L. G. Landsberg V. V. Lapin V. V. Molchanov V. A. Mukhin Yu. B. Novozhilov V. F. Obraztzov V. I. Solyanik V. A. Viktorov A. M. Zaitsev 《Zeitschrift fur Physik C Particles and Fields》1991,50(3):451-454
The radiative decayη′→π + π ? γ has been studied with the statistics of ?2000 events. Different ways of describingm ππ distribution are considered. It is shown that if the dominating contribution to this process is made by the decay channel η′→ργ, then the generally accepted ways of describing the ρ peak do not agree with experimental data. 相似文献
105.
Jitka Dupačová 《Annals of Operations Research》1991,30(1):199-214
Different approaches to statistical sensitivity analysis for optimal solutions of stochastic programs are discussed and compared. Possibilities of drawing conclusions about asymptotic behavior of estimated optimal solutions by means of stability properties of auxiliary randomly perturbed convex quadratic programs are indicated and illustrated on a numerical example. 相似文献
106.
Jitka Dupačová 《Annals of Operations Research》1995,56(1):65-78
The contamination technique is presented as a flexible and relatively easily tractable tool to postoptimality analysis for scenario based multistage stochastic linear programs. It is promising especially in cases when the influence of additional or out-of-sample scenarios on the already solved problem is to be explored.Research supported in part by the Grant Agency of the Czech Republic under Grant No. 402/93/0631. 相似文献
107.
108.
New methods of flow injection analysis (FIA) neutralization titrations of phenothiazine derivatives in aqueous micellar medium of a cationic surfactant using potentiometric and spectrophotometric detection were proposed; titrations with a mixing gradient chamber and high-speed titrations were compared. The FIA titration method in non-aqueous media based on an official method of determination (titration with perchloric acid in anhydrous acetic acid) was also developed. Under optimized reaction conditions and flow-through parameters, the calibration range and equations, the sensitivity, and the repeatability of all methods were found and discussed. All titrations were assayed for medicinal forms. 相似文献
109.
Jitka Caslavska Sarah Molteni Josef Chmelík Karel lais Frantiek Matulík Wolfgang Thormann 《Journal of chromatography. A》1994,680(2):549-559
The behaviour of six substituted aminomethylphenol dyes, having pI values between 5.3 and 10.4, in capillary isoelectric focusing with electroosmotic zone displacement is described. Using untreated fused-silica capillaries and different neutral capillary conditioners in the catholyte, the low-molecular-mass dyes are shown to focus and elute reproducibly in the order of decreasing pI values. In the absence of proteins, the detection times of the dyes are independent of the sampled amount. Hence these substances permit the characterization of the pH gradient produced in this capillary isoelectric focusing method. With concurrent focusing of dyes and test proteins, a macromolecular impact on detection times (reduction of electroosmosis)‘ is revealed. The effect is shown to be dependent on the type and amount of proteins applied and has been observed with three different capillary conditioners. Nevertheless, mapping of the pH gradient with these dyes and determining the pI values of known proteins is shown to provide values in agreement with those in the literature. Hence the substituted aminomethylphenol dyes can be employed as pI markers in capillary isoelectric focusing with electroosmotic zone displacement. Further, focusing and separation of two of the six dyes by preparative recycling free fluid isoelectric focusing is described, illustrating that the substituted aminomethylphenol dyes are also applicable to other free fluid focusing methods. 相似文献
110.
Yu. I. Stozhkov S. V. Viktorov A. A. Kvashnin A. N. Kvashnin V. I. Logachev 《Bulletin of the Lebedev Physics Institute》2016,43(3):102-107
The international space experiment PAMELA was started in the mid-2006 and was finished in the beginning of 2016. The main objective of the experiment was the study of the cosmic ray spectra and elemental composition (including antiproton and positron spectra) in a wide energy range. The main instrument of the PAMELA device is a spectrometer including several detectors. Since the case in point here is the technique of processing the results for high-energy particles (protons, α-particles with energies E ≥ 50 GeV/nucleon, electrons and positrons with E ≥ 50 GeV), the three detectors were mostly used in data processing: a tracker placed into a dc magnetic field, a calorimeter, and a neutron detector. A relatively simple technique for separating electrons and positrons from the total flux of charged particles arriving at the spectrometer and a technique for determining the energy of these particles and constructing their energy spectra are described. This paper is based on the results presented in [1]. 相似文献