Nickel-zinc ferrite nanopowders Ni
0.4
Zn
0.6
Fe
2
O
4
were prepared by glycine (G)–nitrate (N) solution-combustion synthesis and the influence of G/N ratio on their chemical composition, morphology, ...structure, crystallite size, and magnetic behavior was characterized by XRD, EDX, SEM, FTIR spectroscopy, and vibration magnetometry. According to XRD data, the formation of Ni–Zn ferrite gets started at G/N = 0.4. The observed influence of G/N ratio on the structural and magnetic parameters of Ni–Zn ferrites opens up a route to producing powders with crystallite size
D
in the range 24.6–47.1 nm, extent of conversion α up to 94%, coercive force
H
c
from 7.88 to71.78 Oe, remanence magnetization
M
r
from 2.42 to 31.81 emu/g, and saturation magnetization
M
s
from 51.06 to 90.66 emu/g. The maximum values of magnetic characteristics were reached at a stoichiometric ratio of glycine to nitrogen in nitrates (G/N = 0.6).
Abstract
Cement production is a significant source of carbon dioxide emissions. One of the ways to reduce emissions is to reduce the proportion of clinker in cement by introducing active mineral ...additives into its composition, particularly granulated blast-furnace slag. One of the ways to increase the activity of such cement is the effect of magnetic fields on the spin multiplicity of the substances involved in the hardening reaction. In this case, the maximum effect is ensured by introducing a magnetized finely dispersed ferromagnetic substance into the cement composition. The activation effect depends on the additive’s adding method to the cement’s composition, the components ratio in the cement, and the cement hardening mode. This work aims to identify the influence of the adding method of the additive, the slag and additive proportion in cement, and the steam curing temperature on the activity effect of the binder. Three groups of studies were carried out to determine the strength characteristics of laboratory samples hardened both in natural conditions and during steaming. In the first group, cement samples have tested containing 40% slag obtained by joint grinding and joint mixing of the additive with cement for 0.5, 1, 2, 4 and 8 minutes. In the second group, samples have tested with the additive amount varied from 0 to 2.5%, and slag amount from 0 to 80%. Finally, cement samples were tested in the third group containing 50% slag and from 0 to 2.5% additive. The samples were steam cured at temperatures ranging from 50 to 90° C and tested one day, 28 and 90 days after steam curing. As a result of the research, it has revealed that to obtain the maximum effect, the additive must be introduced into the cement composition by joint grinding. The factors influencing the activity have been determined. At the same time, the time of joint grinding should ensure uniform mixing of the components and the formation of new surfaces of cement grains in the presence of magnetic fields. Too long joint grinding leads to the loss of the magnetic properties of the addition. It was found that the activation effect from the additive addition increases with an increase in the proportion of slag. In cement without slag, an increase in the additive content leads to a drop in strength. It was revealed that the introduction of magnetized ferromagnetic dust additives into the composition of the SPC makes it possible to reduce the steam curing temperature of products by 20-25° C. Studies have shown that using a finely dispersed ferromagnetic substance as an activating additive can save energy resources and reduce emissions.
Purpose. Theoretical and experimental evaluation the mechanism of work, bearing capacity and pre-destructive deformations of the anchor system with a new nonadhesive fixing of bolts. Methodology. The ...research is conducted through the analytical method, using the base law of classical elasticity theory, and the method of physical modeling. Laboratory tests on the axial load of bolts are made on a real scale on specimens of concrete filled in metal pipes. Three series of models were tested: two series with fixing bolts with self-expanding mixtures, and one series with adhesive fixing. The results are presented as "stress-strain" graphs. Findings. The range of fluctuation of bearing capacity of "bolt-expanding mixture-rock" system with the change in the main factors is analyzed analytically. The rated bearing capacity of the mentioned system is not less than that of the known energy-absorbing bolts. The mechanism of anchors attached to self-expandable mixtures is determined experimentally. The "load-deformation" curve has rigid and flexible zones, which is characteristic of energy-absorbing bolts. The maximum force of fixing anchors with expanding blends exceeds the effort for bolts fixed by resins more than twice, and the forces in the flexible mode are 67 % larger than the maximum ones in the experiment with fixing Cement KL (Orica) and 99 % more than the UF-MT-15 resin. Originality. The mechanism of active frictional fixing of anchor bolts by means of compression by mixtures extending in a solid phase in the process of hydration hardening is revealed. The created anchoring system has a high bearing capacity with large pre-destructive deformations. The efficiency of fixing anchor bolts with self-expanding mixture with hydration with the formation of pressure 30-50 MPa has been proved. Practical value. The use of research results allows increasing the efficiency of support of roadways by anchoring systems, as well as increasing the stability of rocks at large post elastic deformations.
Abstract
Modern building structures must meet the requirements of efficiency and resource-saving. The main direction for implementing these requirements is to reduce the consumption of steel (14–16%) ...and save cement (10–12%). These tasks can be solved through the rational combination of concrete and steel when they work together and the use of high-strength materials. One embodiment of this task is the use of Concrete Filled Steel Tube (CFST) structures. The purpose of this study is to identify the possibility of using the Drucker-Prager model by comparing the results of test studies on short compressed Concrete Filled Steel Tube (CFST) elements with different strength and deformation characteristics of the concrete core to the results from finite element analysis (FEA) modelling of corresponding CFST elements. Additionally, the behaviour of a steel pipe without a concrete core was investigated. The results show that the FEA method used in this work is sufficiently accurate for studying the behaviours of short CFST elements. The modelling technique adopted in the study made it possible to consider the redistribution of stresses in the concrete and pipe dynamically. The stress distribution patterns inside the concrete during both linear and non-linear deformations of CFST elements, as well as the characteristics of the interaction between the concrete and pipe in the contact zone, have been revealed.
Abstract
This paper presents the preface of the proceedings for the 4th International Conference on Sustainable Futures: Environmental, Technological, Social, and Economic Matters (ICSF 2023), a ...multidisciplinary event that explores the challenges and opportunities of sustainability in various domains. The preface outlines the conference’s objectives, themes, workshops, and topics, as well as its contribution to advancing sustainable development and global dialogue. It also acknowledges the efforts and inputs of various stakeholders who have made the conference possible, especially in light of the pandemic situation. Furthermore, it thanks IOP Publishing for its support and flexibility in facilitating open access publishing. The paper concludes by looking forward to future editions of ICSF and the ongoing quest for a more sustainable and interconnected world. The paper invites readers to delve into the rich and diverse content that shapes this influential conference.
Abstract
This paper represents a preface to the Proceedings of the 3rd International Conference on Sustainable Futures: Environmental, Technological, Social, and Economic Matters (ICSF 2022) held at ...the Kryvyi Rih, Ukraine, 24–27 May 2022. Background information and the organizational structure of the meeting, program committee, and acknowledgments of the contributions of the many people who made the conference a success are presented.
Le point de vue pris au mot Andor, József; Angenot, Marc; Aptekman, Jeanne ...
Cognition, représentation, langage,
06/2016
Journal Article
Peer reviewed
Open access
Ce volume dédié aux travaux de Pierre-Yves Raccah réunit les contributions de ceux qui utilisent ses concepts et valident ou respectent son modèle sur la Sémantique des Points de Vue, mais aussi de ...ceux qui, malgré leurs parcours divergents, reconnaissent que P-Y Raccah marque une étape importante de la grande aventure intellectuelle de la pensée théorique en matière de sémantique instructionnelle d’ordre argumentatif. Les études réunies ici, par leur diversité, sont représentatives non seulement de l’amplitude des sujets qu’a abordés Pierre-Yves Raccah mais aussi des grandes problématiques de construction du sens par lesquelles se tissent les relations entre les courants de pensée dans le domaine des sciences du langage. Ce qui donne au volume son unité, c’est précisément cet horizon commun par lequel les contributions s’éclairent l’une l’autre.
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