scholarly journals Simulation of thermal treatment of mineral wool blanket

2019 ◽  
Vol 298 ◽  
pp. 00091 ◽  
Author(s):  
Anton Pilipenko ◽  
Ekaterina Bobrova ◽  
Boris Efimov
Keyword(s):  
Heat Treatment ◽  
Thermal Treatment ◽  
Mineral Wool ◽  
Energy Costs ◽  
Technological Parameters ◽  
Accelerated Methods ◽  
The Stability ◽  
Over Time

This article describes results of modelling of heat treatment of mineral wool blanket. The properties of mineral wool products are largely determined by the conditions of heat treatment, which is carried out by suction of the heat carrying agent through a layer of mineral wool blanket. The choice of technological parameters and optimization solutions determines both the energy costs of manufacturing mineral wool products and their properties and the stability of these properties over time when used in structures. Optimizing the heat treatment parameters of a mineral wool blanket is a labor-intensive and time-consuming task. The development of accelerated methods based on the analysis of the results of previously conducted and new studies can significantly reduce the time for choosing technological parameters, as well as increase the reliability and adequacy of decisions.

scholarly journals Carbonitration of a Tool for Pressing Stainless Steel Pipes

2020 ◽  
Vol 7 (2) ◽  
pp. C17-C21
Author(s):  
I. V. Ivanov ◽  
M. V. Mohylenets ◽  
K. A. Dumenko ◽  
L. Kryvchyk ◽  
T. S. Khokhlova ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Thermal Treatment ◽  
Heat Resistance ◽  
Alkali Metals ◽  
Matrix Ring ◽  
High Hardness ◽  
Operating Conditions ◽  
Matrix Rings ◽  
Conventional Heat Treatment ◽  
The Stability

To upgrade the operational stability of the tool at LLC “Karbaz”, Sumy, Ukraine, carbonation of tools and samples for research in melts of salts of cyanates and carbonates of alkali metals at 570–580 °C was carried out to obtain a layer thickness of 0.15–0.25 mm and a hardness of 1000–1150 НV. Tests of the tool in real operating conditions were carried out at the press station at LLC “VO Oscar”, Dnipro, Ukraine. The purpose of the test is to evaluate the feasibility of carbonitriding of thermo-strengthened matrix rings and needle-mandrels to improve their stability, hardness, heat resistance, and endurance. If the stability of matrix rings after conventional heat setting varies around 4–6 presses, the rings additionally subjected to chemical-thermal treatment (carbonitration) demonstrated the stability of 7–9 presses due to higher hardness, heat resistance, the formation of a special structure on the surface due to carbonitration in salt melts cyanates and carbonates. Nitrogen and carbon present in the carbonitrided layer slowed down the processes of transformation of solid solutions and coagulation of carbonitride phases. The high hardness of the carbonitrified layer is maintained up to temperatures above 650 °C. If the stability of the needle-mandrels after conventional heat treatment varies between 50–80 presses, the needles, additionally subjected to chemical-thermal treatment (carbonitration) showed the stability of 100–130 presses due to higher hardness, wear resistance, heat resistance, the formation of a special surface structure due to carbonitration in melts of salts of cyanates and carbonates. Keywords: needle-mandrel, matrix ring, pressing, heat treatment, carbonitration.

scholarly journals Optimization of technological parameters of heat treatment of minced fish products in combi steamer

2020 ◽  
Vol 2020 (2) ◽  
pp. 142-152
Author(s):  
Dmitriy Valerevich Titov ◽  
Natalia Vadimovna Dolganova
Keyword(s):  
Heat Treatment ◽  
Optimization Technique ◽  
Target Function ◽  
Energy Costs ◽  
Technological Parameters ◽  
Fish Products ◽  
Energy Value ◽  
Reduced Gradient Method ◽  
Minced Fish ◽  
Generalized Reduced Gradient

The article considers the process of baking minced fish products in the convection mode in a combi steamer as an alternative to roasting them. There has been developed an optimization technique to determine the optimal technological parameters of heat treatment in a combi steamer. Optimization of technological parameters of heat treatment was carried out on the basis of mathematical modeling. To do this, there were used the methods of correlation-regression and variance analysis. An optimization mathematical model consisting of a target function and a system of constraints was constructed. The target function is a two-factor regression model that functionally relates the output of finished products (optimization parameter), temperature, and duration of the baking process. The target function was subject to conditional maximization. The system of constraints consists of one equation and four inequalities. These restrictions take into account the culinary readiness and organoleptic properties of products, energy costs, as well as the range of temperature changes in the working chamber of the combi steamer. The maximum value of the target function, subject to all restrictions, was found in MS Excel software by using the generalized reduced gradient method. In the result, the optimal technological parameters of heat treatment process in the combi steamer were the following: temperature = 231°C, process duration = 11 minutes. At the same time, the yield of finished fish minced products made 86.7%, and energy costs did not exceed 1 kWh. The results obtained have been confirmed experimentally. The finished products have high organoleptic qualities: the total score = 19.5. The nutritional and energy value of tilapia meatballs was determined. In 100 g of product the amount of protein = 12.8 g, fats =3.8 g, carbohydrates = 11.4 g, energy value = 128 kcal.

Behavior of Micro-Alloyed Steel at Thermal Treatment

2017 ◽  
Vol 265 ◽  
pp. 177-180 ◽  
Author(s):  
T.V. Shveyova ◽  
A.M. Pesin ◽  
D.O. Pustovoytov
Keyword(s):  
Heat Treatment ◽  
Thermal Treatment ◽  
Microalloyed Steel ◽  
Alloyed Steel ◽  
Heavy Duty ◽  
Heavy Duty Vehicle ◽  
Micro Alloyed Steel ◽  
The Stability

A tendency towards the growth of grain when heating is investigated and the stability against tempering alloyed and microalloyed steel. The advantage steel, microalloyed by vanadium and nitrogen is shown and their application for heavy-duty vehicle parts is recommended. The possibility of residual forging heat of forgings realization for their heat treatment is established.

scholarly journals Analysis of direct metal laser sintering ‒ DMLS and heat treatment influence on the Inconel 713C nickel alloy structure

2021 ◽  
Vol 93 (3) ◽  
pp. 49-56
Author(s):  
Jakub Ciftci ◽  
Ryszard Sitek ◽  
Jarosław Mizera
Keyword(s):  
Heat Treatment ◽  
Nickel Superalloy ◽  
Laser Sintering ◽  
Direct Metal Laser Sintering ◽  
Technological Parameters ◽  
Cast Material ◽  
Hardness Tests ◽  
Ni3al Phase ◽  
The Stability ◽  
Inconel 713C

The group of nickel based superalloys produced in the DMLS (Direct Metal Laser Sintering) process is limited to materials, which produced conventionally do not have properties to allow to use them for rotating components of aircraft engines. This work attempts to optimize the technological parameters of the DMLS process for the Inconel 713C nickel superalloy. A heat treatment was performed for selected samples to investigate the effect on the morphology of the Ni3Al phase. The microstructure analysis and hardness tests were carried out. The material after the DMLS process was characterized by the presence of much smaller dendrites than the cast material and exceeded its hardness. For the tested variants of heat treatment, the material was characterized by smaller sizes of the Ni3Al phase. In order to ensure the stability of the microstructure, an optimization of the dedicated heat treatment after the DMLS process is required, as the standard heat treatment for Inconel 713C cast nickel superalloy does not fully recrystallize the material.

On the Robustness of Solution Strategy Classifications

2010 ◽  
Vol 31 (2) ◽  
pp. 68-73 ◽  
Author(s):  
María José Contreras ◽  
Víctor J. Rubio ◽  
Daniel Peña ◽  
José Santacreu
Keyword(s):  
Individual Differences ◽  
Study Strategies ◽  
Solution Strategy ◽  
Specific Test ◽  
Spatial Tasks ◽  
The Stability ◽  
Strategy Changes ◽  
Over Time

Individual differences in performance when solving spatial tasks can be partly explained by differences in the strategies used. Two main difficulties arise when studying such strategies: the identification of the strategy itself and the stability of the strategy over time. In the present study strategies were separated into three categories: segmented (analytic), holistic-feedback dependent, and holistic-planned, according to the procedure described by Peña, Contreras, Shih, and Santacreu (2008) . A group of individuals were evaluated twice on a 1-year test-retest basis. During the 1-year interval between tests, the participants were not able to prepare for the specific test used in this study or similar ones. It was found that 60% of the individuals kept the same strategy throughout the tests. When strategy changes did occur, they were usually due to a better strategy. These results prove the robustness of using strategy-based procedures for studying individual differences in spatial tasks.

On the Stability of Evaluative Conditioning Effects

2013 ◽  
Vol 44 (6) ◽  
pp. 380-389 ◽  
Author(s):  
Sabine Förderer ◽  
Christian Unkelbach
Keyword(s):  
Evaluative Conditioning ◽  
Indirect Measures ◽  
The Stability ◽  
Over Time

Evaluative conditioning (EC) refers to valence changes in neutral stimuli (CSs) through repeated pairing with liked or disliked stimuli (USs). The present study examined the stability of EC effects in the course of 1 week. We investigated how this stability depends on memory for US valence and US identity. We also investigated whether CSs evaluations occurring immediately after conditioning (i.e., evaluative consolidation) are necessary for stable EC effects. Participants showed stable EC effects on direct and indirect measures, independent of evaluations immediately after conditioning. EC effects depended on memory for US valence but not for US identity. And although memory decreased significantly over time, EC effects remained stable. These data suggest that evaluative consolidation is not necessary, and that conditioned preferences and attitudes might persist even when people do not remember the concrete source anymore.

scholarly journals Steady-state $$\dot{V}{\text{O}}_{2}$$ above MLSS: evidence that critical speed better represents maximal metabolic steady state in well-trained runners

2021 ◽  
Author(s):  
Rebekah J. Nixon ◽  
Sascha H. Kranen ◽  
Anni Vanhatalo ◽  
Andrew M. Jones
Keyword(s):  
Steady State ◽  
Critical Speed ◽  
Lactate Concentration ◽  
Practical Interest ◽  
Blood Lactate Concentration ◽  
Distance Runners ◽  
Severe Intensity ◽  
The Stability ◽  
Trained Runners ◽  
Over Time

AbstractThe metabolic boundary separating the heavy-intensity and severe-intensity exercise domains is of scientific and practical interest but there is controversy concerning whether the maximal lactate steady state (MLSS) or critical power (synonymous with critical speed, CS) better represents this boundary. We measured the running speeds at MLSS and CS and investigated their ability to discriminate speeds at which $$\dot{V}{\text{O}}_{2}$$ V ˙ O 2 was stable over time from speeds at which a steady-state $$\dot{V}{\text{O}}_{2}$$ V ˙ O 2 could not be established. Ten well-trained male distance runners completed 9–12 constant-speed treadmill tests, including 3–5 runs of up to 30-min duration for the assessment of MLSS and at least 4 runs performed to the limit of tolerance for assessment of CS. The running speeds at CS and MLSS were significantly different (16.4 ± 1.3 vs. 15.2 ± 0.9 km/h, respectively; P < 0.001). Blood lactate concentration was higher and increased with time at a speed 0.5 km/h higher than MLSS compared to MLSS (P < 0.01); however, pulmonary $$\dot{V}{\text{O}}_{2}$$ V ˙ O 2 did not change significantly between 10 and 30 min at either MLSS or MLSS + 0.5 km/h. In contrast, $$\dot{V}{\text{O}}_{2}$$ V ˙ O 2 increased significantly over time and reached $$\dot{V}{\text{O}}_{2\,\,\max }$$ V ˙ O 2 max at end-exercise at a speed ~ 0.4 km/h above CS (P < 0.05) but remained stable at a speed ~ 0.5 km/h below CS. The stability of $$\dot{V}{\text{O}}_{2}$$ V ˙ O 2 at a speed exceeding MLSS suggests that MLSS underestimates the maximal metabolic steady state. These results indicate that CS more closely represents the maximal metabolic steady state when the latter is appropriately defined according to the ability to stabilise pulmonary $$\dot{V}{\text{O}}_{2}$$ V ˙ O 2 .

scholarly journals Physico-Chemical Investigation of Endodontic Sealers Exposed to Simulated Intracanal Heat Application: Hydraulic Calcium Silicate-Based Sealers

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 728
Author(s):  
David Donnermeyer ◽  
Magdalena Ibing ◽  
Sebastian Bürklein ◽  
Iris Weber ◽  
Maximilian P. Reitze ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Thermal Treatment ◽  
Film Thickness ◽  
Physical Properties ◽  
Calcium Silicate ◽  
Setting Time ◽  
Chemical Properties ◽  
Chemical Changes ◽  
Time Flow ◽  
Heat Application

The aim of this study was to gain information about the effect of thermal treatment of calcium silicate-based sealers. BioRoot RCS (BR), Total Fill BC Sealer (TFBC), and Total Fill BC Sealer HiFlow (TFHF) were exposed to thermal treatment at 37 °C, 47 °C, 57 °C, 67 °C, 77 °C, 87 °C and 97 °C for 30 s. Heat treatment at 97 °C was performed for 60 and 180 s to simulate inappropriate application of warm obturation techniques. Thereafter, specimens were cooled to 37 °C and physical properties (setting time/flow/film thickness according to ISO 6876) were evaluated. Chemical properties (Fourier-transform infrared spectroscopy) were assessed after incubation of the specimens in an incubator at 37 °C and 100% humidity for 8 weeks. Statistical analysis of physical properties was performed using the Kruskal-Wallis-Test (P = 0.05). The setting time, flow, and film thickness of TFBC and TFHF were not relevantly influenced by thermal treatment. Setting time of BR decreased slightly when temperature of heat application increased from 37 °C to 77 °C (P < 0.05). Further heat treatment of BR above 77 °C led to an immediate setting. FT-IR spectroscopy did not reveal any chemical changes for either sealers. Thermal treatment did not lead to any substantial chemical changes at all temperature levels, while physical properties of BR were compromised by heating. TFBC and TFHF can be considered suitable for warm obturation techniques.

scholarly journals Simulation of Diffusion Processes in Chemical and Thermal Processing of Machine Parts

Processes ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 698
Author(s):  
Kateryna Kostyk ◽  
Michal Hatala ◽  
Viktoriia Kostyk ◽  
Vitalii Ivanov ◽  
Ivan Pavlenko ◽  
...  
Keyword(s):  
Mathematical Modeling ◽  
Temperature Distribution ◽  
Thermal Treatment ◽  
Diffusion Processes ◽  
Nitrogen Concentration ◽  
The Body ◽  
Functional Dependencies ◽  
Technological Parameters ◽  
Gas Nitriding ◽  
Temperature State

To solve a number of technological issues, it is advisable to use mathematical modeling, which will allow us to obtain the dependences of the influence of the technological parameters of chemical and thermal treatment processes on forming the depth of the diffusion layers of steels and alloys. The paper presents mathematical modeling of diffusion processes based on the existing chemical and thermal treatment of steel parts. Mathematical modeling is considered on the example of 38Cr2MoAl steel after gas nitriding. The gas nitriding technology was carried out at different temperatures for a duration of 20, 50, and 80 h in the SSHAM-12.12/7 electric furnace. When modeling the diffusion processes of surface hardening of parts in general, providing a specifically given distribution of nitrogen concentration over the diffusion layer’s depth from the product’s surface was solved. The model of the diffusion stage is used under the following assumptions: The diffusion coefficient of the saturating element primarily depends on temperature changes; the metal surface is instantly saturated to equilibrium concentrations with the saturating atmosphere; the surface layer and the entire product are heated unevenly, that is, the product temperature is a function of time and coordinates. Having satisfied the limit, initial, and boundary conditions, the temperature distribution equations over the diffusion layer’s depth were obtained. The final determination of the temperature was solved by an iterative method. Mathematical modeling allowed us to get functional dependencies for calculating the temperature distribution over the depth of the layer and studying the influence of various factors on the body’s temperature state of the body.

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