Defining the thermal conductivity of thermally heterogeneous hollow wall bricks used as elements for increasing the comfort of buildings

The article presents numerical calculation analysis in the scope of determining thermal conductivity coefficient λeq [W/(m·K)] of thermally heterogeneous hollow bricks of thermally heterogeneous structure (a combination of structural material with thermal insulation material). Numerical calculations were conducted by means of professional software TRISCO-KOBRU 86, serving thermal circulation analysis in a 2D field in stationary approach. The analyzed hollow wall bricks may be used, for instance, as a structural layer of layered outer walls of a building. In the article also the results of the Uc thermal conductivity coefficient calculations for double-layer walls with the use of the analyzed hollow wall bricks are presented in regard to thermal requirements.

Capsules and Extracellular Polysaccharides in Escherichia coli and Salmonella

Escherichia coli and Salmonella isolates produce a range of different polysaccharide structures that play important roles in their biology. E. coli isolates often possess capsular polysaccharides (K antigens), which form a surface structural layer. These possess a wide range of repeat-unit structures.

Equivalent Resilient Modulus Inversion and Calculation of Different Asphalt Pavement Structures

Based on the modulus inversion theory and the equivalent principle of deflection basin, by analyzing the deflection basin data of each structure layer measured by the FWD, the obtained equivalent resilient moduli of different structural layers in three different structures (a semirigid type Asphalt pavement and two inverted asphalt pavements) were compared. At the same time, the calculated equivalent resilient modulus of the top surface of the structural layer based on the inversion method was used to modify the existing theory formula. The results show that, with the inversion method and the theoretical calculation method, the calculated equivalent resilient modulus of the top surface of the cushion layer has a small error, but the theoretical calculation method overestimates the equivalent resilient modulus of the top surface of the cement stabilized crushed stone layer and the top surface of the graded crushed stone transition layer, especially for the inverted asphalt pavement; by contrast, the corresponding result of the inversion method is closer to the value in actual engineering. While determining the equivalent resilient modulus of the cushion layer, the influence of the thickness of the cement stabilized crushed stone layer needs to be considered, and the inverted asphalt pavement structure should adopt a thicker asphalt layer to reduce the modulus deviation; at the same time, the more the structural layers and the larger the difference in the interlayer modulus ratio, the larger the deviation of equivalent resilient modulus of the top surface of the base layer; for the inverted asphalt pavement and semirigid asphalt pavement, the correction coefficients of the calculation formula of the equivalent resilient modulus of the top surface of cement stabilized gravel layer are 0.35∼0.55 and 0.65∼0.75, respectively. The inversion method can be used to determine the equivalent resilient modulus of each structural layer of the inverted asphalt pavement and semirigid asphalt pavement, and its results can provide a basis for the design of the structure reconstruction of asphalt pavement.

Feasibility Study Comparison of Pavement Designs Using Local Materials

The possibility of using local materials in the construction of structural layers of pavement is considered in the paper. The paper presents a method of technical and economic analysis, for which it is necessary to know the calculated deformation moduli of the materials being compared. Knowing the turnaround time for each of the options under consideration, it is possible, by comparing them with the payback periods, to more fully identify the technical and economic features of such options. The main criterion for the admissibility of the use of local material in the corresponding structural layer is the equal strength of pavement structures or individual structural layers made of local and imported materials. The criterion of economic feasibility of using local material can be written as an inequality. Using the principle of equivalence of systems, it is possible to replace individual structural layers of pavement, made of certain materials, with equivalent layers of stiffness from other materials, increasing or decreasing their thickness, depending on the strength characteristics of the materials themselves. The main condition for the technical feasibility of using local material has been determined on the basis of the condition of equal strength structures made from local and imported materials. A schedule for preliminary determination of the technical and economic feasibility of using local materials in the structural layers of road pavements has been built. The total value of the investment costs can be used as an additional criterion for the economic benefits of the compared options.

Study of the Permeation Flowrate of an Innovative Way to Store Hydrogen in Vehicles

With the global warming of the planet, new forms of energy are being sought as an alternative to fossil fuels. Currently, hydrogen (H2) is seen as a strong alternative for fueling vehicles. However, the major challenge in the use of H2 arises from its physical properties. An earlier study was conducted on the storage of H2, used as fuel in road vehicles powered by spark ignition engines or stacks of fuel cells stored under high pressure inside small spheres randomly packed in an envelope tank. Additionally, the study evaluated the performance of this new storage system and compared it with other storage systems already applied by automakers in their vehicles. The current study aims to evaluate the H2 leaks from the same storage system, when inserted in any road vehicle parked in conventional garages, and to show the compliance of these leaks with European Standards, provided that an appropriate choice of materials is made. The system’s compliance with safety standards was proved. Regarding the materials of each component of the storage system, the best option from the pool of materials chosen consists of aluminum for the liner of the spheres and the envelope tank, CFEP for the structural layer of the spheres, and Si for the microchip.

Modulus Inversion Layer by Layer of Different Asphalt Pavement Structures

In order to improve the accuracy of modulus inversion of the pavement structure layer, a layer-by-layer inversion method was proposed to be compared with the traditional inversion method by inverting the modulus of each structural layer of the inverted asphalt pavement and semirigid asphalt pavement. The results show that the influence of cushion modulus on the modulus of inverted subgrade and modulus of cement-stabilized crushed stone is restricted by the cushion modulus and pavement structure characteristics, and the thicker cement-stabilized crushed stone layer is beneficial for improving inverted modulus of subgrade; besides, for the inverted asphalt pavement, the modulus of the graded crushed stone transition layer has a significant influence on the modulus inversion of cement-stabilized crushed stone. The modulus of the graded gravel transition layer inverted by these two methods is underestimated, the modulus of cement-stabilized gravel is overestimated using the traditional inversion method, and the inversion result of the inverted asphalt pavement is more significantly affected by the inversion method than the semirigid base asphalt pavement. Moreover, the modulus of the pavement structural layer is determined by the material and structural characteristics, and its recommended empirical value or the value in the indoor test does not conform to the actual value of the site; by contrast, the inversion modulus obtained using the layer-by-layer inversion method is closer to the actual value, which can be used in the design of similar pavement structures to accumulate data for determining the material modulus or the pavement structure adjustment coefficient in the pavement structure.

STUDY AND ANALYSIS ON SOUND ABSORBING AND NOISE REDUCING PERFORMANCE OF TIMBER CONSTRUCTION WALL BASED ON ACOUSTIC SPIRAL MATASURFACE

Based on acoustic spiral metasurface, a spiral structural layer was designed to apply to timber construction interior wall. The sound absorption coefficient was measured by impedance tube method and compared with Helmholtz resonance structural layer, solid structural layer and air layer in traditional wall. The results show that the combination of the spiral structural layer and the wall can optimize the sound absorption performance of the wall in the medium and low frequency. Without reducing the overall sound-absorbing performance of the wall, can achieve perfect sound absorption in some medium and low frequency sound bands.

Analysis on cracking of structure layer of cement stabilized graded macadam

Because of its strong bearing capacity, good stability and easy control of construction technology, cement stabilized graded macadam was widely used in highway pavement structure. In order to solve its characteristics of easy cracking, relevant researchers have carried out systematic studies on it, but such studies did not involve the large volume and large scope of the structural layer, and only carried out research on the specimen and small scope. Based on engineering project, the influence of dust content and cement content on the cracking was studied by adjusting the parameters and paving the test section during the production process. At the same time, the cracks in the project were counted, and the influences of exposure time, structural level, traffic load and construction level on the cracks in the cement stabilized graded macadam were analyzed. The relationship between crack spacing and exposure time is established, and through comparative analysis, it is found that construction level is the most important factor affecting crack spacing.

Syntactic evidence against deficiency

The chapter revolves around the notion of deficiency. It is a widely held view that clitics do not have the same distribution as strong pronouns because the former have a deficient inner structure (Cardinaletti and Starke 1999 amond others). By the same token, languages display an intermediate class of weak pronouns, sharing properties of clitic and strong pronouns. The hypothesis of an intermediate class is particularly attractive for a diachronic analysis, as weak elements are the cornerstone of the evolution from strong pronouns to clitics. This chapter provides an in-depth discussion of the status of weak elements with a twofold intent: first, to show that weak pronouns do not form a consistent class across languages and second, to challenge the hypothesis that deficient elements are obtained when the outer structural layer of strong pronouns peels off.

Experimental Analysis of Reinforcement Rust in Cement under Corrosive Environment

In this work, the microstructure characteristics of corrosion products of reinforcement under a corrosive environment with chloride, carbonation and the combination of chloride-carbonization were studied by x-ray photoelectron spectroscopy (XPS) and scanning electron microscopy/energy spectroscopy (SEM-EDX). The results indicate that the outside of the passivation film reacts with the cement slurry to produce Fe–SiO4 in all three corrosive environments. The inner side is not completely corroded. The morphology of the corrosion is different in the three environments. In a chloride environment, corrosion products have obvious cracks, and the local layered structure is dense. In a carbonation environment, the surface of the steel corrosion shows a uniform granular structure and loose texture. With the combination of chloride and combination, the surface of the structural layer of steel corrosion was uneven and accompanied by protrusions, cracking and spalling occurred. The composition of the corrosion substances in the three corrosion environments are mainly composed of FeO, Fe3O4, Fe2O3 and Fe–SiO4. The content of iron oxide increases from a chloride salt, carbonization to the composite environment, indicating that the corrosion degree intensifies successively.