Explore the vast range of titles available.

Structures comprising elements with markedly distinct physical and mechanical properties are ubiquitously employed in engineering applications. The paper considers the motion of an elastic half-strip interacting unilaterally with an absolutely rigid foundation, caused by a longitudinal edge mechanical fast impulse load. Dynamic equations of elasticity theory are used to describe the motion of the half-strip. The method of spatial characteristics is used to model the wave dynamics and dynamic failure of a piecewise homogeneous structure. This method allows to take into account variable conditions at the contact surface of the half-strip and the foundation, and consider delamination processes. The connection of the half-strip to the foundation is modeled by a nonlinear strength function of normal and tangential stresses, taking into account the mechanism of the connection, including its separation. The propagation of elastic waves caused by a non-stationary mechanical action is studied. The calculation results are analyzed to identify the areas of the contact surface that are most susceptible to damage. In order to study the shape of the main and reflected wave fronts at the contact boundary distributions of the values of the velocity components and stresses for different moments in time were obtained. Applications such as non-destructive testing and energy-efficient designs benefit from wave research techniques. The focus on propagation of waves in compound structures could further bridge theoretical advancements with practical implementations, enhancing the structural reliability and functionality of dynamic systems. The proposed method of direct numerical solution allows us to give practical recommendations for the identification of emerging local stress concentrations zones at the mating points.

Design of foundations on an elastic base is carried out using the solution of three-dimensional problems of contact interaction. Improving the accuracy of engineering calculations is necessary to ensure economic efficiency and increase energy savings in green building. The problems of indentation of punches with a flat base bounded by doubly connected close to polygonal contact areas are researched in the present work. Small parameter method is used to obtain explicit analytical expressions for the contact pressure distribution and the punch displacement dependence in a simplified form, which is convenient for engineering practice. The found load-displacement dependence satisfies the known inequalities that are valid for an arbitrary contact domain. Also a numerical-analytical method is in consideration. It uses the simple layer potential expansion and successive approximations for the problems accounting roughness of the elastic half-space. Roughness coefficient is considered as a parameter of regularization of the integral equation for the smooth contact problem. The results of both methods coincide with sufficient accuracy.

The ability of autochthonous microbiota from different water bodies in the northwestern part of the Russian Federation to degrade the highly toxic microcystin-LR (MC-LR) was shown for the first time. The maximum rate of degradation of MC-LR was noted in water samples from Sestroretskij Razliv Lake and Lower Suzdal Lake during the period of mass development of cyanobacteria. In water samples from Lake Ladoga, where no toxic cyanobacterial blooms were previously noted, MC-LR biodegradation proceeded at a much lower rate and with a longer lag phase. The composition of MC-LR biodegradation products indicates the presence in the autochthonous microbiota of the studied objects of microorganisms capable of degrading microcystins both by the mlr mechanism and by the biochemical pathway involving glutathione.

In order to assess the impact of cyanobacteria on mollusks under experimental conditions, the interaction of toxic and nontoxic strains of the cyanobacterium Microcystis aeruginosa (Kützing) Kützing and bivalve mollusks Unio pictorum (Linnaeus, 1758) has been studied. Cyanobacteria have a negative effect on bivalve mollusks: the 40% death of mollusks and deterioration of their adaptive capacity are recorded when cocultivated with M. aeruginosa at a high cell concentration. At the same time, there is no difference in the mortality of mollusks incubated with toxic and nontoxic cyanobacteria. A decrease in the content of microcystin-LR in the presence of bivalves is revealed. No statistically significant increase in the number of cyanobacteria in the water is noted after transit passage through the digestive system of bivalves.

The novel strain SR-1.3 with algicidal properties and the ability to remove microcystin-LR (MC-LR) has been isolated from the water of Lake Sestroretsk Razliv during active cyanobacteria vegetation. Based on the morphological and cultural characteristics and the results of sequencing the ITS region of DNA, strain SR-1.3 was identified as Penicillium chrysogenum . The SR-1.3 strain exhibits algicidal activity against cyanobacteria and green algae. A dose-dependent and species-specific nature of the algicidal action of the P. chrysogenum SR-1.3 strain has been established. Cyanobacteria show the highest sensitivity to strain SR-1.3. The complete lysis (100%) of cyanobacteria cells is observed when 10% (vol) of the culture liquid or the micromycete filtrate are added to the medium. The algicidal effect of strain SR-1.3 on green algae is 30–70%, depending on the culture. According to the level of sensitivity to the algicidal effect of SR-1.3, the test cultures can be arranged in the series Planktothrix agardhii > Microcystis aeruginosa > Aphanizomenon flos-aquae = Anabaena cylindrica > Scenedesmus quadricauda > Oocystis parva . The inhibitory effect of the strain SR-1.3 mycelium on cyanobacteria and green algae growth does not exceed 3–6%. Based on the results, a conclusion was made about the indirect mechanism of the algicidal action of P. chrysogenum SR-1.3 by excretion into the medium of metabolites that inhibit and/or lyse cells of cyanobacteria and green algae. When toxigenic strains M. aeruginosa and P. agardhii are cultivated on a medium containing exometabolites of strain SR-1.3, the concentrations of microcystins in the medium decreases 3.3 and 1.8 times, respectively, compared with control variants. The ability of P. chrysogenum SR-1.3 to remove the highly toxic MC-LR from the cultivation medium is revealed. The MC-LR content is found to decrease from 1.2 to 0.79 μg/mL over 48 h during the cultivation of strain SR-1.3 on a medium with microcystin.

Mathematical model of the complex interaction of composite structures elements is developed. A half-strip composed of two various materials is considered as a case of the composite structure. For each layer the dynamic equations of the theory of elasticity are used. An impact-impulse load is applied at the end of the structure. During the complex interaction, the conjugation of layers is carried out by conditions that ensure joint deformation, slipping (with friction) or absence of contact. The area and the contact type are determined during the solving process. This approach requires the construction of the special numerical algorithm which allows to change the boundary conditions during the calculation depending on the fulfilment of the strength criterion. The problem is solved numerically using method of characteristics. The propagation of elastic waves in the two-layer half-strip is studied. The wave field characteristics are determined in the calculated point of the layer at a given time. The calculation results are analysed in order to identify areas of the contact surface that are most prone to damage. The geometric and mechanical parameters influence on the behaviour of the structure is studied.

The information and communicative competency today is an integral part of professional training in any sphere. Due to the fact that nowadays big amount of work is done or monitored in the remote mode the requirement is stipulated for every specialist to be able to use digital technologies professionally. For a future seafarer it means, first of all, the ability to use modern technologies as the information and data resource and also it presupposes the ability to work with software libraries, to create data bases, to perform necessary calculations by means of cloud services inclusive. This component is of extreme practical importance as it enables the satisfaction of the social mandate to prepare future seafarers for the living in the information environment. The task is quite challenging so it requires the adequate knowledge level. That is why the main objective of the course “Information technologies” together with other subjects within the curriculum for the professional training in maritime academy is to develop the reliable scientific and methodological grounds for the realization of any professionally related tasks of future merchant feet officers. Specially selected tasks acquaint cadets with information technology in terms of implementing the solution of applied professionally oriented tasks, such as navigating the course, determining the location of the vessel, calculating stocks for the trip, etc. Therefore, the obligatory elements of the tasks are: construction of mathematical (computer) models;analysis of possible solutions to the problem; of technological processes, taking into account all factors influencing the process and methods of decision-making;implementation of mathematical models of problems in spreadsheets. This article proposes a strategy for solving an applied problem using an information-modeling approach to the analysis and evaluation of the technological process, namely, the algorithm for calculating the required voyage and storm fuel reserves of a marine vessel. Both office spreadsheets and cloud services were used to implement the mathematical model for solving this problem. The use of “cloud computing” technologies in the training of seafarers is due to the fact that, firstly, while on board, the master or ship mechanic can perform some components of their work, especially joint projects, in modern services, and secondly, these technologies, supporting traditional forms of education, is a new stage in the development of education and a cost-effective, efficient and flexible way to meet the needs of students in acquiring new knowledge.

Laboratory information management systems belong to the class of application software intended for storage and management of information obtained in the course of the work of the laboratory. The systems are used to control and manage samples, standards, test results, reports, laboratory staff, instruments, and work flow automation. Integration of laboratory information management systems with the enterprise’s information systems will make it possible to promptly transmit required data to the laboratory and the enterprise administration.

Contractile reactions of the guinea pig airway smooth muscles in the presence of stannum dioxide nanosized particles were studied. Contractile reactions to cholinergic and histaminergic stimulation were potentiated by inhalations of nanoparticle aerosol and by exposure of isolated smooth muscle segments to nanoparticle suspension.

The article discusses the development of inclusive design in clothing, designed to ensure versatility, accessibility and compliance with modern fashion trends for different audiences. Based on the principles of an integrated approach to the design of inclusive clothing, the directions of implementation for the choice of design solutions have been developed. The result of the research was the development of new patentable functional and constructive solutions for models of inclusive women’s waistcoats, which make it possible to use various groups of consumers, for example, women with atrophy of the lower extremities and moving in a wheelchair.