scholarly journals Device for investigating thermal stability of characteristics of voltage-to-frequiency converters

2021 ◽  
pp. 9-16
Author(s):  
V. A. Zavadsky ◽  
R. Yu. Kharchenko ◽  
S. M. Dranchuk ◽  
V. I. Tsatsko
Keyword(s):  
Thermal Stability ◽  
Mechanical Stress ◽  
Frequency Converter ◽  
Temperature Stability ◽  
Automatic Measurement ◽  
Effect Of Temperature ◽  
Frequency Converters ◽  
Wide Range ◽  
Output Characteristics ◽  
Thermal Stability Of

The article presents the research results on a device for automatic measurement of the temperature stability of the output characteristics of voltage-to-frequency converters. The device can be used to measure mechanical stresses in the ship's hull. The main source of information on the state of the mechanical stress on the hull of the ship is the integrated monitoring system. Monitoring methods are based on measuring the frequency of the output signals from the sensors based on strain gages, which have a wide scatter of values for parameters and characteristics and depend on external factors. A possible solution to this problem is to use a device that would convert the analog sensor signal into a more noise-immune signal of another type, for example, voltage-to-frequency converter. It is for such systems based on synchronous integrated converters that the authors have developed a device for automatic measurement of the temperature stability of the output characteristics of frequency converters. Such device can measure the thermal stability of the convertor automatically, which makes it possible to analyze the effect of temperature on the output characteristics of the converter and to experimentally study the sensors in a wide range of operating temperatures (from room temperature to 70℃). The study of the thermal stability of the characteristics of such sensors made it possible to confirm the quality of its electronic components and to determine which parameters need to be adjusted. The device is a set of units, one of them being a control circuit based on the ATmega-16 RISC microcontroller. This design and the developed algorithm for the device operation makes it possible to determine the output frequency with a high accuracy (with a measurement time of 1 sec, the accuracy reaches 0.05%). The developed device allows finding the ways to increase the thermal stability of mechanical stress sensors based on integral converters.

scholarly journals Effect of High Temperature on the Electrochemical and Optical Properties of Emeraldine Salt Doped with DBSA and Sulfuric Acid

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Salma Gul ◽  
Anwar-ul-Haq Ali Shah ◽  
Salma Bilal
Keyword(s):  
Thermal Stability ◽  
Cyclic Voltammetry ◽  
Sulfuric Acid ◽  
Effect Of Temperature ◽  
Visible Spectroscopy ◽  
Emeraldine Salt ◽  
Higher Temperature ◽  
Stability Effect ◽  
Thermal Stability Of ◽  
Comprehensive Study

A comprehensive study of thermally treated polyaniline in its emeraldine salt form is presented here. It offers an understanding of the thermal stability of the polymer. Emeraldine salt was prepared by a novel emulsion polymerization pathway using dodecylbenzene sulfonic acid and sulfuric acid together as dopants. The effect of temperature and heating rate on the degradation of this emeraldine salt was studied via thermogravimetric analysis. The thermally analyzed sample was collected at various temperatures, that is, 250, 490, 500, and 1000°C. The gradual changes in the structure of the emeraldine salt were followed through cyclic voltammetry, Fourier transform infrared spectroscopy, and ultraviolet-visible spectroscopy. Results demonstrate that emeraldine salt shows high thermal stability up to 500°C. This is much higher working temperature for the use of emeraldine salt in higher temperature applications. Further heat treatment seems to induce deprotonation in emeraldine salt. Cyclic voltammetry and ultraviolet-visible spectroscopy revealed that complete deprotonation takes place at 1000°C where it loses its electrical conductivity. It is interesting to note that after the elimination of the dopants, the basic backbone of emeraldine salt was not destroyed. The results reveal that the dopants employed have a stability effect on the skeleton of emeraldine salt.

Thermal Decomposition of Supersaturated Ti1-xAlxN Solid Solution Synthesized by High-Energy Milling

2016 ◽  
Vol 9 ◽  
pp. 82-89
Author(s):  
Maya Radune ◽  
Michael Zinigrad ◽  
David Fuks ◽  
S. Hayun ◽  
Nachum Frage
Keyword(s):  
Thermal Stability ◽  
Solid Solution ◽  
Spinodal Decomposition ◽  
Density Functional ◽  
Chemical Deposition ◽  
High Energy ◽  
Nucleation And Growth ◽  
Scanning Calorimetry ◽  
Wide Range ◽  
Thermal Stability Of

Supersaturated titanium-aluminum nitride (Ti1-xAlxN) is a very attractive material for a wide range of applications due to its high oxidation and wear resistance accompanied by high strength, hardness, thermal conductivity and thermal shock resistance. Currently, its applications are limited to coatings obtained by physical or chemical deposition. Bulk materials based on Ti1-xAlxN may be fabricated by powder metallurgy approach using powders synthesized by high-energy ball milling (HEBM), which composition corresponds to supersaturated Ti1-xAlxN solid solution. In the present study, thermal stability of the supersaturated Ti1-xAlxN solid solution was investigated. According to the quasi-binary TiN-AlN phase diagram, constructed using density functional theory (DFT) analysis, the concentration ranges, where decomposition takes place through spinodal decomposition or through nucleation and growth, were determined. Experimental study on thermal stability of solid Ti1-xAlxN solution powder was conducted by means of differential scanning calorimetry (DSC), Brunauer-Emmited-Teller (BET) and XRD. The results indicated that spinodal decomposition of Ti1-xAlxN starts at 800°C, while at temperature higher than 1300°C regular decomposition (nucleation and growth) is occur.

High Temperature Stability of SiC/Ti Interface

2011 ◽  
Vol 685 ◽  
pp. 340-344 ◽  
Author(s):  
Tung Wai Leo Ngai ◽  
Chang Xu Hu ◽  
Wei Zheng ◽  
Heng Xie ◽  
Yuan Yuan Li
Keyword(s):  
Thermal Stability ◽  
High Temperature ◽  
Composite Materials ◽  
Temperature Stability ◽  
Diffusion Path ◽  
Interfacial Stability ◽  
Diffusion Couples ◽  
High Temperature Stability ◽  
High Temperature Structural Material ◽  
Thermal Stability Of

Ti, SiC and their composite materials have been widely used as high temperature structural material. The knowledge of interfacial stability between SiC and Ti is vital in high temperature applications. In this study, SiC/Ti diffusion couples were prepared to investigate the interfacial reactions between SiC and Ti at 1273 K. Phase forming sequence, microstructure and thermal stability of SiC/Ti interface were studied. It was indicated that after annealed at 1273 K for 10 days, 4 reaction layers were formed at the SiC/Ti interface. The diffusion path between SiC and Ti is SiC/Ti3SiC2/Ti5Si3/Ti5Si3+TiC/Ti3Si/Ti. As the annealing time prolong, the thicknesses of these reaction layers increased.

THE EFFECTS OF TEMPERATURE UPON PANCREATIC AMYLASE IN SELECTED REPTILES AND AN AMPHIBIAN

1967 ◽  
Vol 45 (2) ◽  
pp. 227-232 ◽  
Author(s):  
Yvette Abrahamson ◽  
Michael Maher
Keyword(s):  
Thermal Stability ◽  
Amylase Activity ◽  
Effect Of Temperature ◽  
Maximum Temperature ◽  
Pancreatic Amylase ◽  
Optimum Temperature ◽  
Preferred Temperatures ◽  
Effects Of Temperature ◽  
Subcellular Level ◽  
Thermal Stability Of

The effect of temperature on pancreatic amylase was studied on three species of reptiles and one amphibian. Pancreata were removed from the animals, homogenized, and assayed for amylase activity by the Caraway procedure. Assays were conducted at various temperatures to determine the optimum temperature of activity and the maximum temperature for thermal stability of pancreatic amylase. It appears that between reptiles and amphibians, and also among species of reptiles, there are thermally dependent differences at the subcellular level which are similar to the differences in the preferred temperatures of the animals.

scholarly journals Thermal Stability of Pepper Leaf Extracts

HortScience ◽  
2004 ◽  
Vol 39 (4) ◽  
pp. 855A-855
Author(s):  
Jeff Anderson*
Keyword(s):  
Thermal Stability ◽  
High Temperature ◽  
Tissue Concentration ◽  
Temperature Stability ◽  
High Temperature Stability ◽  
Leaf Extracts ◽  
Acute Heat Stress ◽  
Dependent Change ◽  
Time Dependent Change ◽  
Thermal Stability Of

Acute heat stress can denature and aggregate proteins. The objective of this study was to determine how changes in the chemical and physical environment affected high temperature-induced turbidity and precipitation in pepper (Capsicum annuum L.) leaf extracts. High temperature stability of leaf extracts decreased as the tissue concentration increased. Control extracts exhibited a time-dependent change in resistance to turbidity and precipitate development, but the presence of polyvinylpolypyrrolidone stabilized the extracts. Ethylenediamine-tetraacetic acid had a less marked effect on turbidity and precipitation. Solution thermal stability increased as buffer pH increased from pH 6.0 to 7.0 regardless of whether the pH was adjusted before or after tissue extraction. Mannitol strongly stabilized pepper leaf extracts, but a surfactant lowered the thermal stability.

scholarly journals Study of the thermal stability of foam of different expansion ratio

2020 ◽  
Vol 29 (3) ◽  
pp. 103-110
Author(s):  
A. V. Koksharov ◽  
S. I. Osipenko ◽  
E. V. Gaynullina
Keyword(s):  
Thermal Stability ◽  
Thermal Exposure ◽  
Expansion Ratio ◽  
Heat Fluxes ◽  
Foam Layer ◽  
Destructive Effect ◽  
Foam Expansion ◽  
Destruction Rate ◽  
Wide Range ◽  
Thermal Stability Of

Introduction. Currently, the industry produces a wide range of foam generators to produce fire-extinguishing foams, and the foams they produce differ significantly in their expansion ratio and, consequently, fire resistance. Since heat fluxes have the main destructive effect on the foam, the purpose of this paper is to establish the patterns of destruction of foam of different expansion ratio when heated.Methods of research. The foam with expansion ratio from 7.5 to 80 was used for the tests. It was obtained by mechanical beating of 6 % solution of foaming agent PO-6RZ. The thermal stability of the foam was studied when the heat flow from the gas burner flame affects the foam layer. During the experiment, the change in the height of the foam column in time was recorded.Results and Discussion. The results of measurements, presented in the form of dependence of foam layer destruction rate on time, quantity of released liquid phase on 1 m2·s, dependence of foam layer destruction rate on its density allowed revealing a number of patterns. The destruction rate of foam with an expansion ratio of up to 30 remains constant throughout the entire duration of thermal exposure. As the foam expansion ratio increases, the rate of destruction at the initial stage of heat flux exposure increases. With a foam expansion ratio of more than 50, there is initially a sharp increase in the rate of destruction, which subsequently decreases as the foam column decreases. In the conditions of the experiment, the best characteristics were shown by the foam with an expansion ratio of 50, because in the foam with a smaller expansion ratio the syneresis makes a significant contribution to its destruction, and the foams with a larger expansion ratio are destroyed by the mechanical effect of convective flame flows.Conclusion. The study of the foam destruction patterns under thermal impact allowed establishing the fact that its destruction is limited by the rate of impoverishment of the upper layers with liquid.

scholarly journals Thermal stability of N-heterocycle-stabilized iodanes – a systematic investigation

2019 ◽  
Vol 15 ◽  
pp. 2311-2318 ◽  
Author(s):  
Andreas Boelke ◽  
Yulia A Vlasenko ◽  
Mekhman S Yusubov ◽  
Boris J Nachtsheim ◽  
Pavel S Postnikov
Keyword(s):  
Thermal Stability ◽  
Differential Scanning Calorimetry ◽  
Thermogravimetric Analysis ◽  
Systematic Investigation ◽  
Scanning Calorimetry ◽  
Wide Range ◽  
C Decomposition ◽  
Thermal Stability Of ◽  
Peak Decomposition

The thermal stability of pseudocyclic and cyclic N-heterocycle-stabilized (hydroxy)aryl- and mesityl(aryl)-λ3-iodanes (NHIs) through thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) is investigated. Peak decomposition temperatures (T peak) were observed within a wide range between 120 and 270 °C. Decomposition enthalpies (ΔH dec) varied from −29.81 to 141.13 kJ/mol. A direct comparison between pseudocyclic and cyclic NHIs revealed high T peak but also higher ΔH dec values for the latter ones. NHIs bearing N-heterocycles with a high N/C-ratio such as triazoles show among the lowest T peak and the highest ΔH dec values. A comparison of NHIs with known (pseudo)cyclic benziodoxolones is made and we further correlated their thermal stability with reactivity in a model oxygenation.

Thermal Stability of NiAl-Base Coatings for High Temperature Application

2005 ◽  
Vol 237-240 ◽  
pp. 709-714
Author(s):  
Robert Filipek ◽  
Marek Danielewski ◽  
E. Tyliszczak ◽  
M. Pawełkiewicz ◽  
S. Datta
Keyword(s):  
Thermal Stability ◽  
Gas Turbines ◽  
Inverse Method ◽  
Critical Role ◽  
Diffusion Coatings ◽  
Aluminide Coatings ◽  
Wide Range ◽  
Industrial Energy ◽  
Temperature Application ◽  
Thermal Stability Of

Aluminide diffusion coatings act as a remedy against the aggressive environments in which modern aero-gas turbines operate. Platinum addition to basic aluminide coatings significantly improves the oxidation resistance of these coatings. The increase in operating temperatures of industrial energy systems and gas turbines, has led to the extensive use of coatings capable of providing improved service life. Interdiffusion plays a critical role in understanding the integrity of such coatings. The Danielewski-Holly model of interdiffusion which allows for the description of a wide range of processes (including processes stimulated by reactions at interfaces) is employed for studying of interdiffusion in the Pt-modified β-NiAl coatings. Using the inverse method the intrinsic diffusivities of Ni, Al and Pt were calculated. Such obtained diffusivities were subsequently used for modelling of thermal stability of Pt-modified aluminide coatings in air and in argon atmosphere.

Conductivity and Thermal-Stability of 5-Sulfosalicylic Acid Sodium Doped Polypyrrole

2010 ◽  
Vol 428-429 ◽  
pp. 579-582 ◽  
Author(s):  
Fu Fang Zhou ◽  
Bao Gai Zhai ◽  
Chun Xu Pan ◽  
Yuan Ming Huang
Keyword(s):  
Thermal Stability ◽  
Particle Size ◽  
Laser Light ◽  
Dopant Concentration ◽  
Laser Light Scattering ◽  
Probe Laser ◽  
Sulfosalicylic Acid ◽  
Wide Range ◽  
Thermal Stability Of

By varying the dopant-to-pyrrole ratio in a wide range from 0 to 60% a series of 5-sulfosalicylic acid sodium doped polypyrrole was synthesized in situ in aqueous solution with ferric chloride as the oxidant. The resulting polypyrroles were characterized with the four-probe, laser light scattering and thermo-gravimetry analysis, differential thermal analysis, respectively. Our results indicate that the particle size plays a determinative role to tune the conductivity in the studied range of dopant concentration; and this series of polypyrrole with size-tuned-conductivity exhibits little less thermal-stability although its size and conductivity changes simultaneously and acutely with the dopant concentration. The association of the conductivity with particle size was interpreted in terms of a theoretical model proposed by Baughman and Shacklelette.

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