In the relational database model introduced by E.F. Codd, the database state is understood as a finite set of relationships between elements. The names of the relationships and their arnts (locations) are fixed and called the database schema. The individual information stored in the relationships of this schema is called the state of the database. Although relational databases were devised for finite sets of data, it is often convenient to assume that there is an infinite domain. We consider relational databases organized over an ordered domain with some additional relations – a typical example is the set of rational numbers together with the relation of linear order and binary operation of addition. If the first-order predicate logic language is used as the query language, then queries can use both database relationships and domain relationships, with variables changing throughout the domain. In the focus of our study are the first-order (FO) queries that are invariant under order-preserving permutations – such queries are called order-generic. It was discovered that for some domains order-generic FO queries fail to express more than pure order queries. Here we prove the collapse result theorem over a weakly o-minimal domain having convexity rank 1 and a small countable spectrum.

This article considers energy-saving technologies for winter concreting of building structures and constructions. Various authors have studied mathematical models of the thermal regime of a three-dimensional building structure. The mathematical model of the heat balance equations in the concrete structure, the thermal conductivity coefficient, the dependences of the heat balance equations in the concrete structure and the junction, the thermal conductivity coefficient, the volumetric thermal conductivity, respectively, in the erected fragment and the previously erected part of the wall was implemented on a computer. The article considers the processes of cement and concrete strength gain during early freezing of concrete. In previous studies by various authors, it was found that with an increase in the time for gaining critical strength, the cost of electricity is reduced by 25-50%, due to the use of thermal inertia of the structure. The rate of cooling of monolithic structures at negative temperatures is revealed. The chemistry of cement hardening processes during early freezing is shown. Thermodynamic calculations set the limits of negative temperatures at which concrete strength curing stops, but under the action of repeated positive temperatures, the cement hydration process resumes and concrete continues to harden. The aluminum minerals of Portland cement clinker are usually the first to hydrate when the cement hardens with water, and in the presence of gypsum they form calcium hydrosulfoaluminate. This connection is very fragile and is destroyed by mechanical stress (repeated vibration) and over time even at normal temperatures. The article reviews the foreign experience of winter concreting and the preferred methods of work in this case.

The present paper concerns the notion of weak o-minimality introduced by M. Dickmann and originally studied by D. Macpherson, D. Marker, and C. Steinhorn. Weak o-minimality is a generalization of the notion of o-minimality introduced by A. Pillay and C. Steinhorn in series of joint papers. As is known, the ordered field of real numbers is an example of an o-minimal structure. We continue studying properties of almost omega-categorical weakly o-minimal theories. Almost omega-categoricity is a notion generalizing the notion of omega-categoricity. Recently, a criterion for binarity of almost omega-categorical weakly o-minimal theories in terms of convexity rank has been obtained. Binary convexity rank is the convexity rank in which parametrically definable equivalence relations are replaced by ∅ - definable equivalence relations. (p, q)-splitting formulas express a connection between non-weakly orthogonal non-algebraic 1-types in weakly o-minimal theories. In many cases, the binary convexity ranks of non-weakly orthogonal non-algebraic 1-types are not equal. The main result of this paper is finding necessary and sufficient conditions for equality of the binary convexity ranks for non-weakly orthogonal non-algebraic 1-types in almost omega-categorical weakly o-minimal theories in terms of (p, q)-splitting formulas.

As it is known, increasing the efficiency of silicon solar cells is one of the most important tasks in modern alternative energy industry. Optimization of the antireflection and passivation layer is the most economical way to increase efficiency. In this work, the effect of pretreatment on the passivation properties of silicon dioxide (SiO₂) films grown by rapid thermal processing (RTP) at annealing temperatures of 900 and 950°C in a dry oxygen atmosphere, was studied. The growth of thin films of SiO₂  on the surface of monocrystalline silicon wafers was carried out in the AS-ONE 150 rapid thermal annealing chamber (France). Measurements of the lifetime of minority charge carriers by the non-contact microwave method showed that the best passivation of the samples is achieved by applying a preliminary three-stage chemical cleaning (RCA) of the surface of the n-type silicon wafers. IR spectroscopy confirmed the formation of a SiO₂  layer by the presence of an intense maximum at 1071 cm^-1, which was attributed to stretching vibrations of the "tensioncompression" type. The results of calculations of the optical constants of the obtained SiO₂  films using the reflection spectra and the SCOUT software show the presence of a silicon dioxide whose refractive index and extinction coefficient are close to the reference.

The thermodynamic description of wax deposition is a relatively new approach to solving the problem of wax precipitation, which the oil and gas industry has been struggling with for a long time. Many models exist in the literature to predict the thermodynamic conditions under which the first paraffin crystal is formed. The first task in all models is to determine the stability of the hydrocarbon mixture in order to define the possibility of wax precipitation. The stability of a mixture is determined by the thermodynamic behavior of the phases of a multicomponent mixture, namely, the presence of all existing phases in equilibrium. To this end, a new stability algorithm with Gibbs energy minimization to determine the wax precipitation in hydrocarbon mixtures has been developed. The algorithm is based on multi-solid thermodynamic model with EOS concepts. The main criterion for stability is the existing of the mixture at its global minimum. Proposed stability analysis predicts whether a given mixture will be split into multiple phases or will exist as the single phase at a given temperature and pressure conditions. The model was proven with 6 samples from fields X and Y showing the instability of original petroleum mixtures that agree with the real behavior of the oil in in-situ conditions. The results of the new stability algorithm are comparable with the results of the models presented previously. The main advantage of the method is its simplicity and reliability.

Pipeline transport is considered to be the most efficient and economically feasible type, unlike rail, land or other types of transportation. Transported products are usually petroleum products with various physical and mechanical properties that can have various negative effects on the pipeline material, thereby causing corrosion, wear, leakage and emissions. The relevance of research in this direction is due to the fact that due to the relatively complex composition of Kazakhstan's oils during oil pumping, triboelectric effects at the phase interface cause the occurrence of electric charges, which lead to an increase in the efficiency of chemical reactions that cause corrosion of the pipeline material. Therefore, it is necessary to develop specific ways to protect oil pipelines from damage caused by metal corrosion. IR spectroscopic analysis of oil shows the presence of various types of hydrocarbons. Based on the oil dispersal of JSC Ozenmunaigas, the complexity in the molecular composition of oil causes electrical effects that lead to an increase in the corrosion rate. All this should be taken into account when developing corrosion protection. In the process of transportation in the volume of oil and petroleum products, due to the complex microstructure and certain heterogeneity of the macrostructure, electrostatic charges can be formed. Since electrification and heat generation occur during tribolytic effects, these processes require refinement of heat transfer processes at the micro-macro level. In this case, the potential difference between individual sections of the liquid volume can be quite large. Chemical and physico-chemical methods of instrumental analysis were used in the work. In this work, experimental values of the specific electrical conductivity of oil and petroleum products were obtained under laboratory conditions, which allow us to judge their dielectric nature. In this work, the triboelectric effect was studied at the site of the boundary of metals and organic liquids (oil, fuel oil, etc.) to determine their effect on the corrosion of pipeline metals. and the values of electrical conductivity of oils and petroleum products are established.