The Influence of the Properties of Thermal - Insulation Materials on the Thermomoist Indicators of a Building

One of the basic measures of energy efficiency in residential buildings is the reduction of heat and coolant pressure, when external structures - walls, ceilings - contain thermal insulation material, as a result of which heat and cold losses are reduced, as a result of air-and moisture permeability. Their number is largely determined by the climatic zone of the building, construction, sources of heat and cold, fuel and electricity prices in this region. In such practice, first of all, attention is paid to the problems of the optimal thickness of the thermal insulator, the installation location, since improper installation in the structure can cause water condensation, which will lead to partial wear of the structure, since the properties of reinforced-concrete layers will deteriorate. This concerns the peculiarities of carrying out thermal insulation works and their necessity both in under construction and in buildings in use. However, even in these conditions, when discussing the thermal effect of thermal insulation on structures, due attention is not paid to individual structures, especially walls, moisture problems. Consideration of insulators with more or less efficient energy and heat engineering characteristics, when it was found that there is a significant difference between their results and effects, aroused particular interest in the study of the problem. This is followed by a study of the influence of the presence of thermal insulation in the structure on the cold load required for cooling, revealed a pattern of cost changes in the case of insulating materials with more or less properties - foam.

Quantifying the optimal thickness in polymer:fullerene solar cells from the analysis of charge transport dynamics and photoabsorption

We provide a semi-empirical equation that quantifies the optimal layer thickness in bulk heterojunction organic solar cells, which is based on time-of-flight and time-resolved microwave conductivity measurements and photoabsorption of a film.

Laser Actuated Microgripper Using Optimized Chevron-Shaped Actuator

In this paper, we propose a laser actuated microgripper that can be activated remotely for micromanipulation applications. The gripper is based on an optothermally actuated polymeric chevron-shaped structure coated with optimized metallic layers to enhance its optical absorbance. Gold is used as a metallic layer due to its good absorption of visible light. The thermal deformation of the chevron-shaped actuator with metallic layers is first modeled to identify the parameters affecting its behavior. Then, an optimal thickness of the metallic layers that allows the largest possible deformation is obtained and compared with simulation results. Next, microgrippers are fabricated using conventional photolithography and metal deposition techniques for further characterization. The experiments show that the microgripper can realize an opening of 40 µm, a response time of 60 ms, and a generated force in the order of hundreds of µN. Finally, a pick-and-place experiment of 120 µm microbeads is conducted to confirm the performance of the microgripper. The remote actuation and the simple fabrication and actuation of the proposed microgripper makes it a highly promising candidate to be utilized as a mobile microrobot for lab-on-chip applications.

Lime compounds for restoration and decoration of building walls

Information on the effect of a polysilicate solution obtained by mixing liquid glass with a silicic acid sol on the structure formation of lime compositions is presented. It was revealed that the amount of specific heat released when lime is wetted with a polysilicate solution is greater than when lime is wetted with water. This is due to the additionally released heat due to the chemical interaction of lime with polysilicate solution. It was found that the introduction of a polysilicate solution accelerates the development of plastic strength. For comparison, we used liquid glass and a sol of silicic acid as an additive. The synergistic effect of the influence of the polysilicate solution on the structure formation of lime finishing compositions was established, which manifests itself in the acceleration of the set plastic strength in comparison with silica sol and water glass. It has been established that the introduction of a polysilicate solution into the lime mixture formulation contributes to an increase in the resistance to slipping of the finishing layer. The optimal thickness of the finishing layer was determined, which is 20 mm, at which sliding from the vertical surface is not observed.

Selection of Effective Thermal Insulation Materials for a Liquefied Natural Gas Tanks

The object of the research is an isothermal tank container for storage and transportation of liquefied natural gases, which requires special operating conditions and is related to a technological facility of increased danger. The purpose of the study is to substantiate the type and thickness of the insulating material to reduce the losses of liquefied natural gas during storage and transportation. Based on the results of the analysis, effective insulation materials were selected for use in cryogenic tanks for isothermal storage of LNG, the optimal thickness of the insulation material was determined, which provides the required level of losses for gas evaporation.

Experimental study on bending behavior of glulam beams strengthened with bamboo scrimber

PurposeIn view of the defects of glued wood beams, a new composite member – reconstituted bamboo board reinforced glued wood beams is proposed to improve the bearing capacity of glued wood beams.Design/methodology/approachThe bending test studied the ordinary glulam beams and the reinforced glulam beams with different layer numbers and different layer thicknesses by comparing with six kinds of glulam beams strengthened with bamboo scrimber and one kind of ordinary glulam beams and used the method of third-point stepwise loading on the glulam beams strengthened with bamboo scrimber.FindingsThe bamboo scrimber improved the bending behavior of the ordinary glulam beams. The 10 mm bamboo scrimber layer can meet the requirements of the maximum ultimate bending capacity and minimize the defects. So 10 mm bamboo scrimber layer was the optimal thickness. During the loading process, the strain change of the normal section of the reconstituted bamboo board reinforced glued wood beam basically conforms to the plane section assumption.Originality/valueThe bending rigidities of the glulam beams strengthened with bamboo scrimber increased up to 28.25%, 8.53% and 76.67%, and the ultimate bending capacity increased from 83.44% to 99.34% with the increase of the bamboo scrimber plate layers (the replacement rate). The ultimate bending capacities and the bending rigidities of the glulam beams strengthened with bamboo scrimber increased to 52.32%∼60.18% and 90.07%∼99.34% with the changing of the bamboo scrimber thicknesses from 7.1 mm to 25 mm.

Stability Analysis of Paste Filling Roof by Cut and Fill Mining

Ensuring the stability of paste false rooves is an important issue in the study of the process of paste filling and slicing mining. Here, a mechanical model of a paste false roof is created to analyze its stability in the process of lower slicing mining in order to determine the minimum slicing thickness of the false roof. We use FLAC3D to simulate and analyze the influence of changes in paste false roof thickness on the stability of the roof. The quantitative functional relationship between the thickness and the subsidence of a false roof, and the optimal thickness of the artificial paste roof, is finally obtained by the development law of the plastic zone in the lower slicing face. The results show that when the thickness of the paste false roof is 3.2 m, the roof can maintain its self-stabilization state and ensure the normal mining of lower layers. Because the same thickness of the upper and lower layers is beneficial for mining replacement and equipment selection in different layered working faces, the optimal thickness of a paste false roof is determined to be 3.2 m.

Method for determining of the optimal thickness of sheets of magnetic cores of electrical machines by the wattmeter method

The problem of reducing magnetic losses (no-load losses) in the steel of the magnetic cores of electrical machines is investigated. The tasc of determining the optimal thickness of steel sheets of the magnetic circuit of an electric machine is considered. The criterion for optimality is the minimum power of magnetic losses in steel. Currently, this problem does not have an exact solution due to the fact that the exact ratio of the hysteresis and eddy current components of magnetic losses in steel is unknown. Analyzed the power of magnetic losses in modern electrical machines and devices, depending on the thickness of the sheets of electrical steel. A method is proposed for determining the optimal thickness of steel sheets of the magnetic circuit of an electric machine based on the wattmeter method. In the course of the experiment, two identical magnetic circuits were selected from steel sheets of different thicknesses, for which the losses in steel were measured at different frequencies of magnetization reversal and the optimal thickness of the sheets was calculated. The proposed formula for calculating the thickness of the sheets is valid for both isotropic and anisotropic steel. The proposed technique can be used for both transformers and electric motors and generators.

4H-SiC Schottky Barrier Diodes for Efficient Thermal Neutron Detection

In this work, we present the improved efficiency of 4H-SiC Schottky barrier diodes-based detectors equipped with the thermal neutron converters. This is achieved by optimizing the thermal neutron converter thicknesses. Simulations of the optimal thickness of thermal neutron converters have been performed using two Monte Carlo codes (Monte Carlo N–Particle Transport Code and Stopping and Range of Ions in Matter). We have used 6LiF and 10B4C for the thermal neutron converter material. We have achieved the thermal neutron efficiency of 4.67% and 2.24% with 6LiF and 10B4C thermal neutron converters, respectively.

The Influence of Process Parameters on Structure and Phase Composition of Boride Coatings Obtained on X39CrMo17-1 Stainless Steel

The boride coatings are characterized by attractive set of properties: high wear resistance and good high-temperature corrosion. In present research the diffusion boride coatings were obtained on X39CrMo17-1 stainless steel. The pack-boriding process was conducted using commercial Ekabor 2 powder. The influence of time of process on thickness and chemical composition was analysed. The boriding process was conducted in 2, 4, 6 hours at 1000 °C using retort furnace. The obtained coating was characterized by double layer structure and contained the FeB in outer layer and Fe2B in inner layer. The thickness of boride coatings increased with process time. The analysis of obtained results showed that the optimal thickness of coating was obtained during 4-h pack boriding.