scholarly journals Numerical modelling of heat treatment of concrete of monolithic structures of buildings in winter conditions of construction

2021 ◽  
Vol 2131 (5) ◽  
pp. 052063
Author(s):  
E Petrov ◽  
S Korobkov ◽  
S Kuznetsov
Keyword(s):  
Heat Treatment ◽  
Energy Efficient ◽  
Thermal Protection ◽  
Curing Temperature ◽  
Insulation Layer ◽  
Ambient Temperatures ◽  
Winter Conditions ◽  
Heating Wire ◽  
Monolithic Structures ◽  
Monolithic Structure

Abstract The paper presents the results of numerical modeling of heat treatment of concrete of a monolithic floor using a heating wire in winter conditions, depending on factors such as ambient temperature, wind speed, isothermal curing temperature, and others. The following parameters were taken as the main parameters for calculating the heat treatment of concrete: the geometric dimensions of the concreting area, the type and dimensions of the thermal insulation layer to ensure thermal protection of the monolithic structure during the heat treatment of concrete, the type and characteristics of transformers that provide the necessary power for preheating and heating concrete of monolithic floors, as well as the class of concrete, cement consumption and type of heating wire. As a result of calculations, the values of the required power for heating concrete of monolithic structures, the number of transformers, the voltage on the transformer for heating the concrete, as well as the duration of the periods of heating, isothermal curing and cooling during the heat treatment of concrete were obtained. As a result of the performed numerical experiments, the modes of heat treatment of a monolithic floor were deter-mined, which ensure the achievement of the required strength of concrete of monolithic structures. This type of heat treatment of concrete during winter periods has established itself as energy efficient and versatile, since heating wires can be used in structures of any type, configuration and reinforcement. With the correct use of heating wires, it is possible to obtain high-quality reinforced concrete structures erected at negative ambient temperatures.

Improvement Of The Method Of Winter Concreting With The Use Of Heating Wires

2019 ◽  
pp. 51-58
Keyword(s):  
Harmful Effect ◽  
Electric Heating ◽  
Strength Development ◽  
Construction Sites ◽  
Dominant Position ◽  
Heating Wire ◽  
Hands On ◽  
Basic Parameters ◽  
Monolithic Structures

Long-term experience of application of a method of electric heating by heating wires of the monolithic concrete and reinforced concrete structures erected in winter conditions is analyzed. This method, developed by the author of the article, took a dominant position on the construction sites due to the simplicity and efficiency in comparison with the mass applied in those years, the method of electric heating of concrete with steel round and strip electrodes. The data on labor intensity, material and energy costs in comparison with the method of rod electric heating are presented. Step-by-step technological operations on preparatory works and electric heating of monolithic structures with the use of extensive hands-on material, which formed the basis for the development of technological regulations, supplemented by a number of new proposals to improve the technology of works, are concretized. In order to work out the optimal mode of heat treatment, the studies of the concrete thermal conductivity factor in the process of its heating and strength development were carried out. The method for calculation of the basic parameters of concrete electric heating is presented. For simplification of calculations, for a wide contingent of masters, superintendents and technical personnel, the nomogram , making it possible with sufficient accuracy under the construction conditions to calculate the necessary heating parameters, was developed. The necessity of grounding the heating wire remaining in the concrete to reduce the harmful effect of magnetic radiation from various appliances and household appliances on the human body is noted.

scholarly journals The Influence of Thermal Protection on Winter Den Selection by Porcupines, Erethizon dorsatum, in Second-Growth Conifer Forests

2005 ◽  
Vol 119 (2) ◽  
pp. 159
Author(s):  
Todd N. Zimmerling
Keyword(s):  
Selection Criteria ◽  
Thermal Protection ◽  
Energetic Cost ◽  
Ambient Conditions ◽  
Erethizon Dorsatum ◽  
Ambient Temperatures ◽  
Type Selection ◽  
Second Growth ◽  
Lower Critical Temperature ◽  
Thermal Cover

I investigated den type selection by Porcupines (Erethizon dorsatum), in relation to the thermal cover provided by the den type, over a period of four winters. Porcupines used log dens, stump dens and rock dens in proportion to the thermal cover provided by each den type. Based on behavioural observations of Porcupines, I assumed that the lower critical temperature for porcupines in my study area was -4°C. Both stump and rock dens provided adequate thermal protection, under most ambient conditions, to allow Porcupines to maintain their body temperature, without increasing basal metabolic rate. In most cases rock and stump dens maintained den temperatures above -4°C until ambient temperatures reached -12°C or lower. In contrast log dens provided poor thermal protection, even in years of thick snowcover. When ambient temperatures dropped below -4°C, den temperatures within log dens were also recorded below -4°C. Log dens were used least often by Porcupines, whereas stump and rock dens were used most often. Despite the large number of potential dens available to Porcupines within the study area, den use was generally limited to three dens per porcupine per winter. The limited use of dens by an individual porcupine during winter may be related to the energetic cost of finding a new den or it may be related to specific selection criteria used by Porcupines.

scholarly journals Impact of Tunnel Temperature Variations on Surrounding Rocks in Cold Regions

2019 ◽  
Author(s):  
Qingyang Yu ◽  
Chao Zhang ◽  
Zhenxue Dai ◽  
Chao Du ◽  
Mohamad Reza Soltanian ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Temperature Field ◽  
Temperature Distribution ◽  
Three Dimensional ◽  
Temperature Fields ◽  
Insulation Layer ◽  
Cold Regions ◽  
Ambient Temperatures ◽  
Temperature Conditions ◽  
Layer Control

Temperature is an important factor in designing and maintaining tunnels, especially in cold regions. We present three-dimensional numerical simulations of tunnel temperature fields at different temperature conditions. We study the tunnel temperature field in two different conditions with relatively low and high ambient temperatures representing winter and summer of northeast China. We specifically study how these temperature conditions affect tunnel temperature and its migration to surrounding rocks. We show how placing an insulation layer could affect the temperature distribution within and around tunnels. Our results show that the temperature field without using an insulation layer is closer to the air temperature in the tunnel, and that the insulation layer has shielding effects and could plays an important role in preventing temperature migration to surrounding rocks. We further analyzed how thermal conductivity and thickness of insulation layer control the temperature distribution. The thermal conductivity and thickness of insulation layer only affect the temperature of the surrounding rocks which are located at distances below ~20 m from the lining.

The Influence of Heat Treatment on the Properties of Breeding Bio-Container

2013 ◽  
Vol 341-342 ◽  
pp. 119-123
Author(s):  
Hong Ying Huang ◽  
Guo Feng Wu ◽  
En Hui Sun ◽  
Zhi Zhou Chang
Keyword(s):  
Heat Treatment ◽  
Thermal Stability ◽  
Water Absorption ◽  
Degradation Rate ◽  
Treatment Process ◽  
Great Influence ◽  
Curing Temperature ◽  
Rice Hull ◽  
Hot Press ◽  
Wet Strength

An environmental, biodegradable breeding container made from rice hull and starch adhesive was produced by a hot-press machine. The heat treatment was introduced to improve the properties of breeding container. The dry and wet strength, water absorption, FTIR, biodegradation, and thermal stability were tested and discussed. The results showed that curing temperature played a great influence of on the dry and wet strength of breeding container. The dry and wet strength was increased with the temperature rise. The water absorption decreased from 89.1% to 50.9%. Pattern of the peak at 3400 cm-1, 2900 cm-1, 1640 cm-1, 1500 cm-1and 1050 cm-1has changed after the heat treatment of specimens. The hydrogen bond was likely produced between straw and adhesive during the heat treatment process. The degradation rate of specimens after heat treatment was lower because the high temperature led to deeper cross-linked reaction. The TGA showed that heat treatment can improve the thermal stability, while the degradability was not changed.

Masking Colored Substrates Using Monolithic and Bilayer CAD-CAM Ceramic Structures

2017 ◽  
Vol 42 (4) ◽  
pp. 387-395 ◽  
Author(s):  
GR Basso ◽  
AB Kodama ◽  
AH Pimentel ◽  
MR Kaizer ◽  
A Della Bona ◽  
...  
Keyword(s):  
Confidence Intervals ◽  
Pearson Correlation ◽  
Lithium Disilicate ◽  
Color Difference ◽  
Color Variation ◽  
Color Coordinates ◽  
Cad Cam ◽  
Ceramic Thickness ◽  
Monolithic Structures ◽  
Monolithic Structure

SUMMARY Objective: To evaluate the masking ability and translucency of monolithic and bilayer CAD-CAM ceramic structures. Methods: Discs of high translucency (HT) and low translucency (LT) lithium disilicate–based ceramic (IPS e.max CAD) with different thicknesses (0.7, 1, 1.5, and 2 mm) were evaluated as a monolithic structure or combined (bilayer) with a 0.5-mm-thick zirconia framework (IPS e.max ZirCAD). The masking ability and translucency were calculated based on CIE L*a*b* color coordinates measured with a spectrophotometer (SP60, X-Rite). The translucency parameter (TP) was calculated using color coordinates measured over standard white-and-black backgrounds. The masking ability was calculated by CIEDE2000 color difference metric (ΔE00) for each specimen measured over a tooth-colored substrate (shade A2) compared to three darker backgrounds (shade C4 and two metal substrates). Confidence intervals (CI) for the means (95% CI) were calculated for TP and ΔE00. The Pearson correlation between ΔE00 and TP was investigated for monolithic and bilayer structures over all backgrounds. Results: The thinner the lithium disilicate layer, the greater the translucency and the higher the ΔE00 values. The effect of ceramic thickness on both translucency and masking ability was more pronounced for the monolithic structures. In addition, monolayers always presented a greater color variation than their bilayer counterparts. The metallic background produced greater ΔE00 than the C4-shaded substrate. Conclusion: Monolithic veneers were able to mask C4-shaded background but did not mask metallic backgrounds. Bilayer structures showed greater shade masking ability than monolithic structures.

scholarly journals Prospects for the implementation of real estate development in Ukraine based on energy efficiency principles and the problems with raising the finance required

2018 ◽  
pp. 5-15
Author(s):  
Lyudmila Swistun ◽  
Taina Zavora ◽  
Yuliia Khudolii
Keyword(s):  
Energy Efficiency ◽  
Real Estate ◽  
Energy Efficient ◽  
Energy Savings ◽  
Thermal Protection ◽  
Housing Stock ◽  
Real Estate Market ◽  
Point Of View ◽  
Real Estate Development ◽  
Residential Real Estate

The main goal of the study is to analyse the residential real estate market in Ukraine from the point of view of the need and the possibility of increasing its energy efficiency. Also, it aims to justify effective financial and credit mechanisms for ensuring measures to improve the thermal protection properties of residential and non- residential real estate, in particular by introducing energy efficiency development projects. With this research we investigated Ukraine's housing stock and utility tariffs and concluded that a beneficial strategy to be applied in Ukraine is the energy-efficient retrofit of real estate. This is one of the most effective ways to re-profile unclaimed real estate units in the existing state or to reconstruct inefficiently used buildings. Also, we reviewed selected methods of energy efficient residential real estate development and mechanisms of financing energy- efficient renovation of real estate used in the EU. And, in our view, the next step of the Ukraine in the direction of improving the energy efficiency of housing should be the effective operation of a dedicated/specific energy efficiency fund to ensure stable financing of housing modernization projects, which will allow for a comprehensive renovation of buildings and lead to significant annual energy savings in this end-use sector.

scholarly journals Heat Treatment Technology of Porous Building Materials with Predictability of Thermophysical Properties

2018 ◽  
Vol 7 (3.2) ◽  
pp. 501
Author(s):  
Mustafa Baba Babanli ◽  
Liubov Shumska ◽  
Maryna Leshchenko
Keyword(s):  
Heat Transfer ◽  
Heat Treatment ◽  
Porous Material ◽  
Thermophysical Properties ◽  
Building Materials ◽  
Process Development ◽  
Thermal Protection ◽  
Raw Material ◽  
Technological Parameters ◽  
Treatment Technology

The work is devoted to theoretical and experimental research of thermophysical features of the creation of new porous heat insulating materials, precisely: research of thermodynamic parameters of the heating processes, swelling and drying of materials; substantiation of the choice of the raw mixture method formation and determination of the optimal energy parameters of the swelling process; development of mathematical models of material heat treatment process and methods of basic technological parameters determination; development of advanced technologies for thermal protection of buildings and power equipment. Experimentally determined dependencies of technological parameters of heat treatment of the raw material mixture in the discharge, its composition, which allows obtaining material with minimal thermal conductivity. Also, the resulting dependencies ensure to find the required mode of heat treatment for the given thermophysical properties. The experimental setup has been developed, which provided to determine the basic laws of heat transfer of porous material, on the basis of which data were obtained, which allow to carry out an estimation of heat transfer and exchange characteristics of the new dispersed porous material necessary for technological calculations. A complex mathematical model of the heat energy mode of the building was created, as well as a program for solving the equations of this model, which makes it possible to determine the basic energy characteristics.  

scholarly journals A Microfluidic Device for Automated High Throughput Detection of Ice Nucleation of Snomax®

Micromachines ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 296
Author(s):  
Priyatanu Roy ◽  
Margaret House ◽  
Cari Dutcher
Keyword(s):  
Heat Treatment ◽  
Microfluidic Device ◽  
High Throughput ◽  
Pure Water ◽  
Ice Nucleation ◽  
Food Storage ◽  
Detection Methods ◽  
Microfluidic Platform ◽  
Ambient Temperatures ◽  
Effects Of Aging

Measurement of ice nucleation (IN) temperature of liquid solutions at sub-ambient temperatures has applications in atmospheric, water quality, food storage, protein crystallography and pharmaceutical sciences. Here we present details on the construction of a temperature-controlled microfluidic platform with multiple individually addressable temperature zones and on-chip temperature sensors for high-throughput IN studies in droplets. We developed, for the first time, automated droplet freezing detection methods in a microfluidic device, using a deep neural network (DNN) and a polarized optical method based on intensity thresholding to classify droplets without manual counting. This platform has potential applications in continuous monitoring of liquid samples consisting of aerosols to quantify their IN behavior, or in checking for contaminants in pure water. A case study of the two detection methods was performed using Snomax® (Snomax International, Englewood, CO, USA), an ideal ice nucleating particle (INP). Effects of aging and heat treatment of Snomax® were studied with Fourier transform infrared (FTIR) spectroscopy and a microfluidic platform to correlate secondary structure change of the IN protein in Snomax® to IN temperature. It was found that aging at room temperature had a mild impact on the ice nucleation ability but heat treatment at 95 °C had a more pronounced effect by reducing the ice nucleation onset temperature by more than 7 °C and flattening the overall frozen fraction curve. Results also demonstrated that our setup can generate droplets at a rate of about 1500/min and requires minimal human intervention for DNN classification.

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