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

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.

Is Open Science Neoliberal?

The scientific reform movement, which is frequently referred to as open science, has the potential to substantially reshape how science is done, and for this reason, its socio-political antecedents and consequences deserve serious scholarly attention. In a recently formed literature that professes to meet this need, it has been widely argued that the movement is neoliberal. However, for two reasons it is hard to justify this wide-scale attribution: 1) the critics mistakenly attribute the movement a monolithic structure, and 2) the critics' arguments associating the movement with neoliberalism are highly questionable. In particular, critics too hastily associate the movement’s preferential focus on methodological issues and its underlying philosophy of science with neoliberalism, and their allegations regarding the pro-market proclivities of the reform movement do not hold under closer scrutiny. What is needed are more nuanced accounts of the socio-political underpinnings of scientific reform that show more respect to the complexity of the subject matter. To address this need, we propose a meta-model for the analysis of reform proposals, which represents methodology, axiology, science policy, and ideology as interconnected but relatively distinct domains, and allows for recognizing the divergent tendencies in the movement.

CALCULATION OF THE CONSTRUCTION OF THE SEWERAGE COLLECTOR DURING ITS REPAIR AND RESTORATION IN AN OPEN WAY

A significant part of sewerage networks in cities in the country are reinforced concrete pipelines with a diameter of 500 to 1500 mm, which lie at a small depth. In many cases, they transport wastewater to treatment plants through areas free of traffic and pedestrians. These factors allow you to effectively perform repair and restoration work in an open way. Corrosion processes that occur in the surface part of the collectors lead to the destruction of the basement. The tray part of the collectors, which is constantly filled with wastewater, remains intact. As studies have shown, the preserved tray part can be successfully used as a fixed formwork and support element in the restoration of the basement of the collector. In this case, to create a new basement part of the collector, in place of the destroyed, it is advisable to use a monolithic structure of polymer concrete reinforced with composite reinforcement. These works are performed using pneumatic and inventory formwork. To implement the proposed structure, it is necessary to perform a preliminary calculation of its load-bearing capacity, provided that it rests on the preserved tray part. As a result of this work it is possible to receive economy in comparison with use for repair and restoration works of polyethylene and fiberglass pipes of necessary diameter. During the calculation, a model of the collector was considered, consisting of a preserved tray part of the collector made of concrete class C12 / 15, the upper part of the collector made of concrete class C20 / 25. The calculation proved the possibility of using polymer concrete structures for repair and restoration of sewers in an open way, provided that the new basement rests on the preserved tray part. The proposed open method allows to significantly reduce the cost of repair and restoration work in comparison with the use of polyethylene and fiberglass pipes.

Thin Floor Milling Using Moving Support

During milling the thin floor of a pocket which locates on a monolithic structure, it is very difficult to achieve high accuracy and good surface quality due to its low rigidity. In this paper, a novel approach is proposed to overcome the difficulties that encountered during milling of the thin floor. The method is realized by using small axial depth of cut but placing a moving support at the back surface of the thin floor during machining, in which the support will move with the cutter at the same velocity. An experimental platform is built to demonstrate the validation of the proposed method. The experimental results show that the proposed method can effectively improve the accuracy and surface quality during milling the thin floor of a pocket of the monolithic structure.

A New Model of Mathematics Education: Flat Curriculum with Self-Contained Micro Topics

The traditional way of presenting mathematical knowledge is logical deduction, which implies a monolithic structure with topics in a strict hierarchical relationship. Despite many recent developments and methodical inventions in mathematics education, many curricula are still close in spirit to this hierarchical structure. However, this organisation of mathematical ideas may not be the most conducive way for learning mathematics. In this paper, we suggest that flattening curricula by developing self-contained micro topics and by providing multiple entry points to knowledge by making the dependency graph of notions and subfields as sparse as possible could improve the effectiveness of teaching mathematics. We argue that a less strictly hierarchical schedule in mathematics education can decrease mathematics anxiety and can prevent students from ‘losing the thread’ somewhere in the process. This proposal implies a radical re-evaluation of standard teaching methods. As such, it parallels philosophical deconstruction. We provide two examples of how the micro topics can be implemented and consider some possible criticisms of the method. A full-scale and instantaneous change in curricula is neither feasible nor desirable. Here, we aim to change the prevalent attitude of educators by starting a conversation about the flat curriculum alternative.

Achieving Highly Anisotropic Three-Dimensional, Lightweight, and Versatile Conductive Wood-Graphene Composite

Functionality of wood has to evolve with time to adapt to the emerging needs in society. In this work, endowing electrical conductivity to the insulating wood by adding graphene into the wood matrix to form a conductive wood-graphene composite (conductive wood) via a facile and environmentally benign fabrication technique. The rationale of fabricating conductive wood is of two folds: (1) The high suitability of wood as a renewable matrix due to its porous network and mechanically robust monolithic structure. (2) The need to explore reasonable strategy to adequately translate the properties of graphene from microscopic level to macroscopic level. The conductive wood is able to preserve both the natural features of wood (to function as mechanical scaffold) and the conductivity of graphene. An outstanding electrical conductivity (volume resistivity of 36.7 Ω·cm) is achieved for the conductive wood, while it can maintain a low bulk density of 0.44 g cm-1. More significantly, the conductive wood demonstrates a highly three-dimensional anisotropic conductivity that makes it a highly versatile conductor in various applications. Hence, this lightweight conductive wood may contribute towards a great electronic revolution and as an encouraging strategy to repurpose the function of wood in this new era.

Hybrid Implant Abutments: A Literature Review

Ceramic implant abutments are becoming increasingly popular due to the growing esthetic demands of patients. Two-piece ceramic abutments have the advantages of both ceramic and titanium abutments. This study aimed to review the published articles regarding hybrid abutments and their characteristics.Published articles regarding two-piece abutments were retrieved by electronic search of PubMed, Embase, Scopus, Medline, and Google Scholar databases using certain keywords. Articles highly relevant to our topic of interest were selected and reviewed.The presence of titanium inserts in hybrid abutments can overcome the brittleness of ceramic, increase the overall fracture resistance, prevent the implant connection wear, and provide better marginal fit compared with one-piece zirconia abutments. Hybrid abutments enable the fabrication of monolithic metal-free implant restorations with optimal esthetics. Furthermore, the risk of porcelain chipping, which is a common complication of implant restorations, is eliminated due to the monolithic structure of these restorations.According to the available literature, hybrid implant abutments have shown promising results with regard to optimal esthetics in the rehabilitation of the esthetic zone. However, long-term clinical studies are required to assess the long-term durability of all-ceramic restorations supported by hybrid abutments.

Enacting community health: Obesity prevention policies as situated caring

Drawing on Critical Policy Studies and feminist STS, this article conceptualizes obesity prevention activities as ongoing and precarious practices of relating – rather than as means for ‘getting results’ or vehicles through which normative discourses are instilled. It focuses on ‘community approaches’ within public health, whose aim is to stimulate healthy initiatives from what policy makers term ‘bottom-up’, emerging from the situations, concerns and abilities within neighbourhoods. Drawing on ethnographic research on the ‘Amsterdam Healthy Weight Programme’, I demonstrate that different practices of relating enact particular versions of health and community. I warn that reliance on statistics-based problem definitions, dietary advice and professional hierarchies preconfigures health promotion as a matter of ‘reaching out’ to particular ‘problem populations’ defined around class and ethnicity. I show, however, that community approaches may also foster spaces for ‘situated caring’, where health emerges in the negotiation of heterogeneous goods, including neighbourhood revival, togetherness and fun. Situated caring has effects that cannot be captured by obesity prevalence statistics. The study of health promotion policies as practices of relating highlights that policy is not a monolithic structure of plans and commitments but is continuously done and redone. The article, then, introduces a new evaluative field that critically articulates the diverse ways in which ideals such as engagement and health are enacted in practices.

Sol-Gel Processing of a Covalent Organic Framework for the Generation of Hierarchically Porous Monolithic Adsorbents

Covalent organic frameworks (COFs) have emerged as a versatile materials platform for applications including chemical separations, water purification, chemical reaction engineering and energy storage. Their inherently low mechanical stability, however, frequently renders existing methods of pelletisation ineffective contributing to pore collapse, pore blockage or insufficient densification of crystallites. Here, we present a general process for the shaping and densifying of COFs into centimetre-scale porous monolithic pellets without the need for templates, additives or binders. This process minimises mechanical damage from shear-induced plastic deformation and further provides a network of interparticle mesopores that we exploit in accessing analyte capacities above those achievable from the intrinsic porosity of the COF framework. Using a lattice-gas model, we accurately capture the monolithic structure across the mesoporous range and tie pore architecture to performance characteristics in both gas storage and separation applications. Collectively, these findings represent a substantial step in the practical applicability of COFs and other mechanically weak porous materials.

Sol-Gel Processing of a Covalent Organic Framework for the Generation of Hierarchically Porous Monolithic Adsorbents

Covalent organic frameworks (COFs) have emerged as a versatile materials platform for applications including chemical separations, water purification, chemical reaction engineering and energy storage. Their inherently low mechanical stability, however, frequently renders existing methods of pelletisation ineffective contributing to pore collapse, pore blockage or insufficient densification of crystallites. Here, we present a general process for the shaping and densifying of COFs into centimetre-scale porous monolithic pellets without the need for templates, additives or binders. This process minimises mechanical damage from shear-induced plastic deformation and further provides a network of interparticle mesopores that we exploit in accessing analyte capacities above those achievable from the intrinsic porosity of the COF framework. Using a lattice-gas model, we accurately capture the monolithic structure across the mesoporous range and tie pore architecture to performance characteristics in both gas storage and separation applications. Collectively, these findings represent a substantial step in the practical applicability of COFs and other mechanically weak porous materials.