We study nonlinear dynamics of two coupled contrast agents that are micrometer size gas bubbles encapsulated into a viscoelastic shell. Such bubbles are used for enhancing ultrasound visualization of blood flow and have other promising applications like targeted drug delivery and noninvasive therapy. Here, we consider a model of two such bubbles interacting via the Bjerknes force and exposed to an external ultrasound field. We demonstrate that in this five-dimensional nonlinear dynamical system, various types of complex dynamics can occur, namely, we observe periodic, quasiperiodic, chaotic, and hypechaotic oscillations of bubbles. We study the bifurcation scenarios leading to the onset of both chaotic and hyperchaotic oscillations. We show that chaotic attractors in the considered system can appear via either the Feigenbaum cascade of period-doubling bifurcations or the Afraimovich–Shilnikov scenario of torus destruction. For the onset of hyperchaotic dynamics, we propose a new bifurcation scenario, which is based on the appearance of a homoclinic chaotic attractor containing a saddle-focus periodic orbit with its two-dimensional unstable manifold. Finally, we demonstrate that the dynamics of two bubbles can be essentially multistable, i.e., various combinations of the coexistence of the above mentioned attractors are possible in this model. These cases include the coexistence of a hyperchaotic regime with an attractor of any other remaining type. Thus, the model of two coupled gas bubbles provides a new example of physically relevant system with multistable hyperchaos.
The preference of sweetened foods can be influenced by a variety of biological, psychological, sociological, and environmental factors. In this study, we focused on differences across three distinct societies: 1) a modern society (i.e., Polish people, n = 199), 2) forager-horticulturalists from Amazon/Bolivia (Tsimane', n = 138), and 3) traditional hunter-gatherers from Tanzania (Hadza, n = 81). To measure sweet preference, participants were asked to drink three cups containing slightly acidic solutions (pH = 2.79) varying in sucrose concentration (w/v; 0%, 25%, 67%). Only 5% of the Polish participants chose the sweetest cup as their favorite, while this cup was chosen by 74% of the Hadza and 53% of the Tsimane’ participants. Further, age was an inversely related to sweet preference for Polish participants; however, age did not predict preferences for both Tsimane’ and Hadza tribes. We discuss our findings in the context of environmental and cultural differences between the participating populations.
The key regulator in the control of aggressive behavior is dopamine receptors. Association of variants in these genes with aggression has been shown in modern populations. However, these studies have not been conducted in traditional cultures. The aim of our study was to investigate population features in distributions of allele and genotype frequencies of DRD2 rs1800497, DRD4 120 bp Ins, and DRD4 exon III polymorphisms and their associations with aggressive behavior in the traditional African populations of Hadza and Datoga, which display a contrast in their culturally permitted aggression. Overall, 820 healthy unrelated Hadza and Datoga individuals were studied. Self‐rated scores of aggression were collected using Buss and Perry's Aggression Questionnaire. Polymerase chain reaction‐Restriction fragment length polymorphism (PCR‐RFLP) was used to determine the genotype of each individual. We show that the Hadza and the Datoga differed significantly in allele and genotype frequencies of all studied loci. Our association analysis detected that only ethnicity and sex of individuals significantly influenced their aggression rank, but we failed to identify any associations of DRD2 rs1800497, DRD4 120 bp Ins, or DRD4 exon III polymorphisms with aggression. Thus, our data have no strong evidence to support the involvement of polymorphisms of DRD2 and DRD4 in controlling aggressive behavior.
Since the 1970s, scholars have produced a large body of research attempting to establish the mechanisms by which sexual serial killers come to arrive at a life of repeat fatal violence. From the standpoint of developmental psychology, however, the explanations offered are far too limited in scope. Human development is the product of complex reciprocal transactions that occur between an individual and their environment throughout their life span. This present study is meant to encourage a critical reconsideration of past knowledge (mainly static traits) in favor of the recognition of the complexity of human development. Using life span developmental psychology as a guiding framework, this study traces the developmental mechanisms that come together to shape the psychopathology that drives the motivations of sexual serial killers.
Studies have been carried out to determine the velocity head acting on aircraft in the upper atmosphere, and to analyze the stability of the meter parameters and its errors using the method of probabilistic studies of the stability of the output characteristics of the membrane-capacitance converter of the velocity head.The study took into account the random nature of the deviations of the structural and electrophysical parameters under the influence of destabilizing factors and in the conditions of mass production. The optimum frequency of electromechanical conversion is determined. The calculated dependencies of the transfer function of the transducer are obtained to assess its stability and to select the optimal frequency of electromechanical conversion.
In many ways the prospects of industry in Russian Federation are determined by the implementation of the National technological initiative which aims to create a new economy within the “Industry 4.0” concept. Considering the prospects of development of the domestic industry for the next decades, it should be noted that today the corresponding process in many respects is defined by the realization of the National Technological Initiative (NTI). The analysis of the NTI structure shows that one of the major directions of such development would be the implementation of advanced manufacturing technologies and the creation of the Future Factories. A preliminary literature overview in the respective area has shown that most of the studies consider the questions of product design as a basic part of product lifecycle. At the same time there is a lack of methodological developments in the area of design of technological processes within advanced manufacturing systems. For this reason, it is important to investigate the development of instruments for justification of manufacturing systems functioning within the «Industry 4.0» concept. We have offered to use the advanced paradigms of imitating modeling, the discrete, the event and the agent, for the description of basic and auxiliary processes realized in production systems. We have determined the main requirements for the processing of manufacturing systems.Comparing such requirements with the specifics of the existing approaches to organizational design of manufacturing systems provided a basis for concluding that the simulation modeling approach is effective. The justification of the technological process parameters by using simulation modeling is substantiated, the main principles are defined.
The results of the information technologies intensive development and implementation processes, recently defined as digitalization, were the basis of the significant changes in the domestic economy. At the same time, it is important to understand that digitalization process require an appropriate response in order to create an environment, which promote to development of strategically valuable economic sectors, include the industrial manufacturing. These circumstances determined the motivation of implementing at the state level such programs as the Digital Economy and the National Technological Initiative, that are aimed at creating conditions for the development of industry in the context of the digitalization.
Focusing on the logistics systems and industrial enterprise supply chains functioning processes, it is important to note, that new opportunities are opened due to development and implementation of information technologies in the economy digitalization context. These opportunities consist in the exchange of information between the individual production, logistics and auxiliary systems and their elements, as well as the products and the external environment, which in general will allow forming big data sets. Herewith, the result of processing the relevant data sets will form basis of the continuous improvement processes through self-organization and self-decision by the active system components.
At the initial stages of the study, a literature overview was done in the field of logistics system organizing within the contemporary concepts of industrial production development, including the Industry 4.0 concept. This has shown that on the one hand, there is a significant impact of digitalization processes on the organization and functioning of logistics system, but on the other hand, there is a lack of methodological developments in the area of these systems design.
For this reason, it is important to investigate the development of instruments for justification of logistics processes functioning characteristics within digitalization context. For this, a generalized structure of the digital logistics system was offered and the requirements for the functioning processes were determined. Taking into account a special aspects of this structure and functioning requirements, we offered to use simulation modeling tools in the organizational design problems. It is proposed to use traditional paradigms of simulation, which include discrete-event and agent-based modelling. On a separate note the possibility of applying the approach at the junction of these two paradigms, which implying the use of their main advantages: using the discrete-event modeling in the simulation of functioning process where the logistics system is describes as the multi-agent environment.
In the article the special features of globalization in present time are examined. It is shown that the period of serious structural changes in the economic, political, ideological spheres as a result of the completion of an extensive increase in the world economy began. The prospects of Russia under the conditions of the contemporary «epoch of changes» are examined.
The paper analyzes the possibility of flight into the orbit around the translunar libration point using gravity-assist maneuver near the Moon. The orbits, which spacecraft can enter without the use of intermediate maneuvers after the flyby of the Moon, are studied. The flight from a parking low-Earth orbit into different orbits is simulated. Color maps of characteristics dependent on the parameters of the flyby point and the map showing the areas on the plane corresponding to the quasi-halo orbit, moving on which the spacecraft does not go to the penumbra of the Moon are constructed.
The question of ensuring reliability, especially of durability of mobile communication systems on the stage of planning, is considered in this paper. The purpose of this work is rising quality of projection radio engineering devices (their components) of mobile communication systems. Research of real methods for calculating the indicators of longevity radio engineering devices was conducted for aim achievement. They have some disadvantages, because according to industry standards 4.012.013-84 they use constant value of variation coefficient in mathematical expression. Unified method in the form of IDEF0-diagram was proposed for elimination of defects. It allows to remove quantification of the durability of the constituent parts of the mobile communication systems of «resource» type. Method consists of five successive steps: the formation of source data, updated calculation of variation coefficient, calculation of storage time, evaluation of complex load factor and calculating of indicators of «resource» type. Notably attention is paid to calculating of updated variation coefficient, which makes a significant contribution to the result. It was detected that it is necessary to apply complex load factor in mathematical expressions in the evaluation of resource of radio engineering devices of mobile communicational systems, because it considers both electrical load and temperature, which is explained by the thermally dependent electrical parameters of electrical components. A summary table of the mean group value of the coefficient of variation for certain subgroups of electrical components was compiled. This table is accessory to counting indicators of durability of «resource» type if the necessary electronics are not available in handbooks about reliability. The calculation of the quantitative values of the durability of the video transmitter with the construction of visual dependencies of gamma-percent resource on the complex load factor was completed. Dependences that have been obtained mirror underestimation of gamma-percent resource with the method which is given in industry standards 4.012.013-84 compared with the proposed. It is recommended to integrate the results of research into methodology of calculating of reliability indicators of «resource» type of components at enterprises and research institutes engaged in the development of mobile communication systems.
The development of the domestic economy from the beginning of the 21st century is characterized by the growth of energy resources export volumes, including coal. That circumstance determined the increased demand for the design, research and modernization of export bulk cargo terminals. Growth of customers requirements and outdated standards, regulations and specifications define the need to improve design’ quality. An article covers issue of justification of material handling technology in the stockyard area of the export bulk cargo terminal within organizational and technical design. These terminals have a large throughput capacity and a unidirectional material flow which determine their narrow specialization and increased demands of ensuring reliability for terminals’ functioning. Providing of material handling technology in the stockyard area based on using specialized high-performance equipments with stream-flow transportation – stackers and reclaimers, as well as their combined type – stacker-reclaimers. That circumstance defined appropriateness of the problem research of equipment selection type (separate or combined) taking into account special aspects. To solve this problem, we used simulation methods that allowed to create a simulation model of the stockyard area functioning and to carry out experiments of parameters variation. The results allowed to estimate the range of incoming and outgoing flow intensity, which determines preference of choosing schemes with separate or combined equipment’ type. A formalized selection process by using the qualimetry methods based on a system of criteria was offered in reason of accounting special aspects of functioning within justification of the most effective material handling technology with increased accuracy. Mathematical tool, which used in proposed selection procedure, allows to taking into account many parameters, including qualitative characteristics, in spite of difficulty to present them in concrete values form. Thus, accounting special aspects of functioning becomes possible, which in general allows to substantiate the most effective material handling technology.